Setting Standards
Chemistry
Electronic Chemicals Global Technical Support and Development
Application
Safety
Customer Analytics
Packaging Logistics
Setting Standards The Development of Standards in the Field of Electronic Chemicals Dr. Wolfgang J. Sievert Honeywell Specialty Chemicals, Seelze Germany
Summary The quality requirements for wet processing chemicals have been increasing during the past 25 years in line with the increasing complexity of the semiconductor devices. In the beginning, the needs of the industry and the abilities of the supplier community were not well reflected by generally applicable standards. After a breakthrough in the early nineties, however, global activities in the field of standardization enhance not only the proliferation of standards but also cost reduction programs contribute to their global utilization.
The Economic Background The global semiconductor industry has been subject to considerable turmoil during the past 4 years. In the general recession of 1996 and 1998 all regions were affected and in some areas even fabs were closed down or major investments postponed. Looking at the situation in a larger time frame, however, shows that ups and downs have been always part of the semiconductor business and that inspite of the industry's cycle the long term growth rate is still at 15 % per year and the cycles do not affect the long term growth (cf. the authors paper in Semiconductor Fabtech 10th Edition pp. 199-204. Semiconductor industry in Europe represents about 25 % of the global semiconductor market today and has been hit not as much as the US and Japan by the recent depression. Also the recovery rate seems to be faster in Europe and the regional growth trends from 1998 to 2003 are estimated at 20 % per year being higher than the comparable growth trends for US and Japan. It is apparent that the role of Europe within the global semiconductor community has become stronger during the past years and the forecast data give rise to an optimistic view on the future. Looking into the material forecast, it becomes apparent that the wet chemical area has forecast growth rates comparable to the other materials and ancillaries essential for semiconductor manufacturing. The 1998 to 2001 forecast, as presented on the ISS 1999 in Rome, is plus 37.8 % for wet chemicals which is
Published in Semiconductor FABTECH 13th editon
W. J. Sievert
Page 1
Electronic Chemicals TSD
again an indicator for the fact
that
wet
chemical
processing is a vital part in the
manufacturing
Fig. Fig. 1
The Major Process Chemicals
$750 Million Worldwide
of
Individual product mix dependent on technology and device type
Phosphoric Acid 6%
Other 5%
Sulfuric Acid 16%
Ammonium Hydroxide 9%
semiconductor devices. In addition the overall product
Nitric Acid 4%
Hydrochloric Acid 7%
portfolio of wet processing chemicals expands due to the introduction of new
Hydrogen Peroxide 25%
Hydrofluoric Acid 17%
technologies. But it is also the introduction of new
Isopropyl Alcohol 11% Source APEC 2/99
The Key Commodities
technologies which leads to a change in volume consumption of chemicals. In specific the big volume products of the past, Sulfuric acid and Hydrogen peroxide, are hit by new cleaning technologies. Among the main products still used for cleaning purposes during the manufacturing process are Sulfuric acid, Hydrogen peroxide, 2Propanol, and Ammonium hydroxide whereas the group of chemicals used for structuring the silicon or silicon oxide surfaces includes Hydrofluoric acid as virtually the key chemical of semiconductor technology. (Fig. 1) According to the complexity of the manufacturing process and the sensitivity of highly integrated devices, specific quality requirements have been developed and established by the industry.
Chemical Product Specifications Historically, at the time of the development of the first
Fig. Fig. 2
Development of Chemical Product Specifications High Purity Hydrofluoric acid
semiconductor devices, high purity
chemicals
were
available only for laboratory use. (Fig. 2) A typical laboratory specification
chemical for
Hydro-
fluoric acid in 1950, 2 years after the invention of the
Year Number of check parameters
Impurity level (metals)
Application history
1950 1968 1970 1978 1981 1990 1996 1998
5 - 100 ppm 5 - 10 ppm 1 - 10 ppm 10 - 500 ppb 10 - 50 ppb 10 ppb 1 ppb 100 ppt
Laborator use Laboratory use Electronic Grade MOS Grade VLSI Grade ULSI Grade SLSI Grade XLSI Grade
7 9 30 40 40-50 50 + 50 + 50 +
Milestones in analytical instrumentation: Multi element AAS, ICP-OES, ICP-MS, HR-ICP-MS
transistor, consisted of a From the First Transistor to the Global Information Society in 50 Years
total of 7 check parameters
Published in Semiconductor FABTECH 13th editon
W. J. Sievert
Page 2
Electronic Chemicals TSD
and the metallic impurity levels were somewhere in the range between 5 and 100 ppm. 20 years later the chemical industry or rather the manufacturers of laboratory chemicals became aware of the new emerging industry and the electronic grade chemicals were created. For these the number of check parameters was increased to around 30 and the impurity level established at 1 to 10 ppm. In the subsequent years semiconductor companies forwarded product specifications reflecting their product requirements for wet processing chemicals and within a couple of years the higher quality grades MOS, VLSI and ULSI were developed. It is important to notice that the development of specifications was of course subject to the analytical capabilities of the laboratories. Typical milestones which enhanced the development of more and more stringent specifications were the introduction of multi element atomic absorption (AAS), inductive coupled plasma - optical emission spectroscopy (ICP-OES), inductive coupled plasma - mass spectroscopy (ICP-MS) and finally the high resolution - inductive coupled plasma - mass spectroscopy (HRICP-MS).
Fig. Fig. 3
Technology Roadmap Quality Roadmap for Electronic Chemicals in Relation to Device Integration
Apart from the development
(Vison of 1989)
1000
of the analytical capabilities,
Metals (ppb) Particles (>0.5µm/ml)
100
technology road maps played an important part in the
10
development of specifications
1
and requirements. (Fig. 3) An
0,1
IBM road map from 1989, having the exceptional beauty of being valid up to now,
Source: IBM 1989
0,01
1
4
16
64
256
Linear Approximation - the Easy Way
clearly describes the relation between device integration (from 1 - 256 M) and the metallic impurity level as well as the particle level of the chemicals for the 1 MB Dram. For example a VLSI quality with metallic impurities around 50 ppb and particle levels of 250 P/ml was estimated to be sufficient. From this range a linear approach was taken to get to the 10 ppb level of metallic impurities for the 4 MB and a 1 ppb level of metallic impurities for the 16 MB Dram. Considering the limited analytical capabilities of 1989, the line, however, makes a small bend towards the 64 and 156 M Dram which according to this road map would require a 0.1 ppb level of metallic impurities in the chemicals. These predictions are astonishingly close to reality and today the 0.1 ppb quality is in fact applied for the manufacturing for the most advanced devices.
Published in Semiconductor FABTECH 13th editon
W. J. Sievert
Page 3
Electronic Chemicals TSD
From the chemical perspective the standard specifications like electronic grade (EG) or VLSI still somehow reflect the natural abundance of the individual elements in the environment. So the maximum values for elements like Iron, Calcium, and Sodium are
Fig. Fig. 4
specified considerably higher than
those
for
the
Electronic Chemicals Purity Roadmap
rare Metallic Impurities in Electronic Chemicals
elements or noble metals. In
10000
the course of the development
Non-Critical Chemicals
1000
and probably for the sake of the
natural
ppt
uniformity,
100
e.g. HF, H2 O2 , NH4OH
distribution of elements was
10
disregarded in the next step
1
and for a ULSI specification
Critical Chemicals
Analytical Capabilities
Reflecting 80 % of elements
0,1 1998
all metallic impurities are Technology
limited to a max of 10 ppb.
1999
2000
0.18µm
2001
2002 2003
0.15µm
0.13µm
2004
2005
The same approach is taken for the 1 ppb level (SLSI) and the 0.1 ppb level (XLSI). Here, however, already a conflict arises with the limited capability of the analytics so that for some elements larger tolerances are requested. This situation is illustrated in the electronic chemicals purity roadmap which next to the device related quality requirements also considers the development of the analytical capabilities. (Fig. 4)
Standardization of Specifications As the expected growth rates for wet chemicals are in line with the industry forecasts and new technology requires different chemistries and different specifications, the question is now: "How is this development accompanied and influenced by SEMI® standards?" It is interesting to note that the standard Electronic Grade and EG MOS quality level was already established in the suppliers industry in 1970. (Fig. 5) It took, however, 8 more years for SEMI® to establish and publish the SEMI® base standard in the book of standards. This base standard was then afterwards applied for more than 10 years as the only " SEMI® standard". After SEMI® had established its European office in Brussels and the European Chemicals and Gases Committee was formed, it was immediately recognized by the committee members that the SEMI® base standard did not at all reflect the requirements of the European semiconductor community. The group very soon came forward with a proposal to design and implement the VLSI quality level for key
Published in Semiconductor FABTECH 13th editon
W. J. Sievert
Page 4
Electronic Chemicals TSD
chemicals to get closer to the existing requirements of the
Fig. Fig. 5
Specifications Applied Implementation of Quality Levels into Standards and Industrial Production
customers and also to the state of art of electronic chemicals
Published in SEMI BOSS Implemented in Industry
manufacturing. The committee
10-500 ppb
EG/MOS
had to overcome a number of
10-100 ppb
VLSI
< 10 ppb
ULSI
< 1 ppb
SLSI
< 100 ppt
XLSI
different obstacles and a lot of convincement work had to be done. It finally was not before
2000
1998
1996
1994
1992
1990
1988
1986
1984
1982
1980
for the most important wet
1978
1976
1974
1972
1970
1994 that the VLSI guidelines
Breakthrough in 1990
processing chemicals passed the ballots and were implemented into the book of standards. In chemical manufacturing the VLSI quality level had been established already in 1981. It can definitely be regarded as one of the successes of the European Chemicals Committee that it initiated ideas to improve the standards for chemicals and consider higher quality levels. The breakthrough came in 1990 when the ULSI level was established in industrial manufacturing at the same time when the corresponding SEMI® standard (Grade 2) was published in the BOSS. After 1990 the work of the US Chemical and Guidelines Committee became very much accelerated and somehow visionary, already 2 years later in 1992 the SLSI (1 ppb) Guideline was released. The industrial implementation of this quality level at least for the key chemicals in Europe took another 4 years. It should be mentioned that the implementation of SLSI and XLSI production levels in the supplier industry utilized to a large extend the results of the European JESSI-Project. The final step was the release of the XLSI guideline (0.1 ppb) which for the key chemicals was achieved in 1998 in industrial production.
Production of Electronic Chemicals Just based on history EG and MOS Grade chemicals are just selected from technical grade materials produced in bulk by qualified manufacturers. (Fig. 6) Even the VLSI level can be achieved by mere selection based on the expertise of the analytical laboratories and an additionally applied filtration to remove the particles. For many years these two steps, selection of the material on the basis of analytical data and filtration to remove particulate impurities, were the only ones applied to generate electronic chemicals out of technical grade materials. With the introduction of the ULSI level of chemicals selection and filtration in some cases was not sufficient and additional purification technology had to be
Published in Semiconductor FABTECH 13th editon
W. J. Sievert
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Electronic Chemicals TSD
developed. It is one of the Fig. Fig. 6
Manufacturing vs Distribution
TechnicalGrade Material Produced in Bulk by Qualified Manufacturers
HP HP Production Production
UHP UHP Production Production
SLSI SLSI
inherent advantages of wet XLSI XLSI
processing chemicals that almost all of them can be
Selection, Selection, Purification Purification &&Filtration Filtration
ULSI ULSI
purified
by
applying
a
simple physical operation, such as distillation. In some
Selection Selection * * &&Filtration Filtration
VLSI VLSI
Selection Selection* *
E.G. E.G.and and MOS MOSGrades Grades
* few exceptions
Production Paths for Electronic Chemicals
cases
also
ion-exchange
technology is used and other
separation
technologies.
But
in
general, even most of the ULSI chemicals can be manufactured using selected technical materials. This scene changes completely with the introduction of the SLSI and later on even the XLSI quality levels. For SLSI levels all metallic impurities for example are limited to max. 1 ppb which is a problem for two types of metallic impurities. First, the metallic impurities which are inherent contaminants to the process and secondly, the metallic impurities which are the so-called ubiquitous elements, elements which are allover the place and might get into the product by random cross contamination. In the case of ultra high purity manufacturing to yield XLSI (0.1 ppb) products, the situation is even worse. In this field not only special equipment is required but also a complete isolation of the manufacturing areas from the environment is absolutely Fig. Fig. 7
Product Specifications
necessary.
Product Specifications Published in SEMI BOSS 1998 EG / MOS
VLSI
ULSI
SLSI
obvious
It
is
quite
that
the
XLSI
manufacturing
H3PO4 H2SO4
translate
HNO3 HF
Highest purity requirements for chemicals coming into contact with bare silicon
H2O2 HCl NH4OH
efforts
directly
into
manufacturing
costs.
While electronic grade,
BOEs
VLSI and to a certain
NH4F sol. IPA
extend also ULSI grade
NMP MeOH
products share almost the
NBA Acetone Acetic acid
same manufacturing and distribution
Solutions for Everyone
costs,
for
SLSI products there is
Published in Semiconductor FABTECH 13th editon
W. J. Sievert
Page 6
Electronic Chemicals TSD
already a substantial increase while for XLSI products the manufacturing and distribution costs increase almost exponentially. So we will find very high costs at the high end. With the economic background mentioned before, semiconductor industry has become very much cost conscious during the past years. While, of course, also depending on company philosophy in the past the guideline - the purer the better - was applied, the situation has changed today. Improved knowledge about the impact of impurities on the performance or reliability of a semiconductor devices and the overall problem of manufacturing costs finally promoted the guideline that the highest purity requirements should be established only for those chemicals which come into direct contact with the bare silicon. (Fig. 7) This idea is very well reflected in the SEMI® book of standards where XLSI guidelines are published for the key chemicals Hydrofluoric acid, Hydrogen peroxide, Hydrochloric acid and Ammonium hydroxide. All of which are substantial ingredients even of most advanced cleaning technologies.
The Value of Standardization Considering the real production paths of electronic chemicals, the few existing standards and the vast variety of individual customer specifications, it seems like there has always been a great misunderstanding
Fig. Fig. 8
Number of Specs for HF and H2SO4
between
the involved parties. The specification data base of a
25
24
HF 40/50% H2SO4
20
13 9
5
4
0 MOS
VLSI
EG
than 750 specifications. With
4
2 0 E.G.
265
specifications. a total of mor
7 5
files
VLSI, 181 ULSI and 77 SLSI
11 10
supplier
specifications, 85 MOS, 147
16
15
15
typical electronic chemicals
ULSI
SLSI XLSI
The number of active specifications for HF 40/50 % and H2SO4 96 % seems to be related to the importance of the wet chemical
the number of chemicals used in
the
manufacturing
of
Semiconductor devices being somewhere (around
around 50
25
including
specialties), the total number of product specifications unacceptably high. Let us focus on two of the leading chemicals, Hydrofluoric acid - concentration range 40-50 % and Sulfuric acid 96 %. (Fig. 8) While Sulfuric acid as already mentioned before belongs to the commodity products, Hydrofluoric acid is definitely the key chemical of the specialty group. The broader application of Hydrofluoric acid also
Published in Semiconductor FABTECH 13th editon
W. J. Sievert
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Electronic Chemicals TSD
for critical and advanced processes is reflected by the higher number of specifications. In the ULSI/SLSI range we find a total of 29 specifications for Hydrofluoric acid versus only 7 specifications for Sulfuric. Of course, the differences between the individual specifications are in many cases not very substantial if not to say almost negligible, Fig. Fig. 9
The Cost of Variety
but as the specifications are customer specific and in most
Cost model based on the consumption of HF 40-50 % ULSI (10 ppb) ppb) and SLSI (1 ppb) ppb) grades
cases part of the commercial Average consumption of 10 european wafer fabs Total consumption
40,000 l/a
40,000 l/a
400,000 l/a
400,000 l/a
Typical production lot size
10,000 l
Average lot size per order
2,500 l
10,000 l
contract, the suppliers have to accept them. The number of specifications not only lead to
Total number of lots
160
40
an enormous administrational
Average number of required analytical checks
120
50
effort, but also in many cases
Cost of analytical check on ULSI/SLSI level
1,300 $
1,300 $
Total analytical costs
162,000 $
67,500 $
to a significant waste of money. A model calculation (Fig. 9) for HF 40-50 %
Saving 58 % on analytical costs
ULSI and SLSI with typical production lot sizes of 10,000 liters and a total industrial demand of 400,000 liters per year by an average of 10 European wafer fabs, results in potential cost savings of 58 % on analytical costs. If standardization of the chemical specifications on let us say 4 relevant quality levels could be achieved, a number of cost saving issues could be implemented effectively. Larger production batches lead to lower warehousing costs and increased flexibility. The reduced number of specifications also reduces the number of part-numbers and labels as well as the necessity for individual safety stocks. What are the proposed actions? 1. Focus and implement 4 relevant quality levels, being in line with the actual situation in the production of high purity chemicals. 2. Reduce the number of specifications in line with the published SEMI® standards guaranteeing the availability of just the right material for the various levels of technology. 3. Increase production batch sizes and hence lower the cost of production and increase the flexibility in product delivery. 4. Standardize on packages and connect systems to enable cost saving material pools.
Published in Semiconductor FABTECH 13th editon
W. J. Sievert
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Electronic Chemicals TSD
Apart from product specifications SEMI® standards have a lot more to offer for the supply chain for electronic chemicals. (Fig. 10) There are two fields of SEMI® activities which directly or indirectly supply value to the electronic chemicals business. 1.
SEMI® chemical specifications and guidelines
2.
SEMI® analytical methods
3.
SEMI® container guidelines
4.
SEMI® traceability standards
While SEMI® chemical specifications would be an issue for production and quality control the SEMI® traceability standards are a universal feature affecting production, quality control, transportation, storage, consumption and Fig. 10
finally waste management of
electronic
SEMI® Support Network
chemicals.
Unfortunately, there is still a
How can SEMI Standards affect the Supply Chain for Electronic Chemicals ?
limited overlap between the Production Production
areas
and
the
general
willingness
to
apply
Quality Control Quality Control
Transport Transport
standards developed in one of the four areas is still small.
Cost
SEMI SEMI Chem. Chem.Specs. Specs.
SEMI SEMI Anal. Anal.Methods Methods
Storage Storage
SEMI SEMI Container Container Guidelines Guidelines
Consumption Consumption
Waste Mgmt. Waste Mgmt.
SEMI SEMI Traceability Traceability Stand. Stand.
reduction
initiatives and globalization trends enhanced by global purchasing activities, however, have reactivated the activities and positively influenced the general acceptance. Economic pressure and the application of some common sense will eventually lead to a situation where few standardized products are delivered in customer specific packages thus bringing variety to a point where it makes sense. Several attempts during the past years to standardize containers and connections found themselves confronted with large obstacles mostly related to the historically grown infrastructure of older fabs. But also in this area it is again cost saving which may lead to a critical review of existing systems and the concentration on fewer optimized logistic systems.
Published in Semiconductor FABTECH 13th editon
W. J. Sievert
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Electronic Chemicals TSD
Globalizing the Business with SEMI® Standards The development within the semiconductor industry during the past few years has clearly shown that the situation for chemical suppliers has substantially changed. (Fig. 11) Technological development together with economic pressure have led to the outphasing of older non-profitable systems and the implementation and development of new concepts of chemical manufacturing
and
distribution.
Among the prerequisites for a year 2000 chemical supplier we will find a trend from selection towards ultra high purity manufacturing. The use of performance packages and the turn from simple selling to integrated chemical management.
Fig. Fig. 11
Changing World for Chemical Suppliers
Prerequisites for Y2K Y2K Chemical Chemical Suppliers Suppliers ý From From Selection Selection towards towards UHP UHP Manufacturing ý Development of Performance Packages Packages ý From From Simple Simple Selling to to Integrated Chemical Chemical Management ý Product Stewardship for Customer Support Support in EHS Issues ý Provide Waste Management Management Support Support ý System Integration Integration and Management Management ý Strategic Alliances Alliances to to Close Gaps ý Global Global Presence and Support ý From From Chemical Chemical Supplier Supplier to to Solutions Provider Provider
Chemistry
Application
Safety
Customer Analytics
Packaging Logistics
Global opportunities for global players
Other activities required today and tomorrow
include
product
A Global Business Needs Global Support
stewardship for customer support in environmental, health and safety issues, waste management support, system integration and last not least the formation of global alliances. As the chemical supplier of the 80s and early 90s has now changed to become a solution provider, the adoption and application of standards is becoming an issue more important than ever before. Standardization is going to be the solution for cost effective materials management for the benefit of materials suppliers and semiconductor manufacturers.
Published in Semiconductor FABTECH 13th editon
W. J. Sievert
Page 10
Electronic Chemicals Global Technical Support and Development
Application
Safety
Customer Analytics
Packaging Logistics
Setting Standards The Development of Standards in the Field of Electronic Chemicals Dr. Wolfgang J. Sievert Honeywell Specialty Chemicals, Seelze Germany
Summary The quality requirements for wet processing chemicals have been increasing during the past 25 years in line with the increasing complexity of the semiconductor devices. In the beginning, the needs of the industry and the abilities of the supplier community were not well reflected by generally applicable standards. After a breakthrough in the early nineties, however, global activities in the field of standardization enhance not only the proliferation of standards but also cost reduction programs contribute to their global utilization.
The Economic Background The global semiconductor industry has been subject to considerable turmoil during the past 4 years. In the general recession of 1996 and 1998 all regions were affected and in some areas even fabs were closed down or major investments postponed. Looking at the situation in a larger time frame, however, shows that ups and downs have been always part of the semiconductor business and that inspite of the industry's cycle the long term growth rate is still at 15 % per year and the cycles do not affect the long term growth (cf. the authors paper in Semiconductor Fabtech 10th Edition pp. 199-204. Semiconductor industry in Europe represents about 25 % of the global semiconductor market today and has been hit not as much as the US and Japan by the recent depression. Also the recovery rate seems to be faster in Europe and the regional growth trends from 1998 to 2003 are estimated at 20 % per year being higher than the comparable growth trends for US and Japan. It is apparent that the role of Europe within the global semiconductor community has become stronger during the past years and the forecast data give rise to an optimistic view on the future. Looking into the material forecast, it becomes apparent that the wet chemical area has forecast growth rates comparable to the other materials and ancillaries essential for semiconductor manufacturing. The 1998 to 2001 forecast, as presented on the ISS 1999 in Rome, is plus 37.8 % for wet chemicals which is
Published in Semiconductor FABTECH 13th editon
W. J. Sievert
Page 1
Electronic Chemicals TSD
again an indicator for the fact
that
wet
chemical
processing is a vital part in the
manufacturing
Fig. Fig. 1
The Major Process Chemicals
$750 Million Worldwide
of
Individual product mix dependent on technology and device type
Phosphoric Acid 6%
Other 5%
Sulfuric Acid 16%
Ammonium Hydroxide 9%
semiconductor devices. In addition the overall product
Nitric Acid 4%
Hydrochloric Acid 7%
portfolio of wet processing chemicals expands due to the introduction of new
Hydrogen Peroxide 25%
Hydrofluoric Acid 17%
technologies. But it is also the introduction of new
Isopropyl Alcohol 11% Source APEC 2/99
The Key Commodities
technologies which leads to a change in volume consumption of chemicals. In specific the big volume products of the past, Sulfuric acid and Hydrogen peroxide, are hit by new cleaning technologies. Among the main products still used for cleaning purposes during the manufacturing process are Sulfuric acid, Hydrogen peroxide, 2Propanol, and Ammonium hydroxide whereas the group of chemicals used for structuring the silicon or silicon oxide surfaces includes Hydrofluoric acid as virtually the key chemical of semiconductor technology. (Fig. 1) According to the complexity of the manufacturing process and the sensitivity of highly integrated devices, specific quality requirements have been developed and established by the industry.
Chemical Product Specifications Historically, at the time of the development of the first
Fig. Fig. 2
Development of Chemical Product Specifications High Purity Hydrofluoric acid
semiconductor devices, high purity
chemicals
were
available only for laboratory use. (Fig. 2) A typical laboratory specification
chemical for
Hydro-
fluoric acid in 1950, 2 years after the invention of the
Year Number of check parameters
Impurity level (metals)
Application history
1950 1968 1970 1978 1981 1990 1996 1998
5 - 100 ppm 5 - 10 ppm 1 - 10 ppm 10 - 500 ppb 10 - 50 ppb 10 ppb 1 ppb 100 ppt
Laborator use Laboratory use Electronic Grade MOS Grade VLSI Grade ULSI Grade SLSI Grade XLSI Grade
7 9 30 40 40-50 50 + 50 + 50 +
Milestones in analytical instrumentation: Multi element AAS, ICP-OES, ICP-MS, HR-ICP-MS
transistor, consisted of a From the First Transistor to the Global Information Society in 50 Years
total of 7 check parameters
Published in Semiconductor FABTECH 13th editon
W. J. Sievert
Page 2
Electronic Chemicals TSD
and the metallic impurity levels were somewhere in the range between 5 and 100 ppm. 20 years later the chemical industry or rather the manufacturers of laboratory chemicals became aware of the new emerging industry and the electronic grade chemicals were created. For these the number of check parameters was increased to around 30 and the impurity level established at 1 to 10 ppm. In the subsequent years semiconductor companies forwarded product specifications reflecting their product requirements for wet processing chemicals and within a couple of years the higher quality grades MOS, VLSI and ULSI were developed. It is important to notice that the development of specifications was of course subject to the analytical capabilities of the laboratories. Typical milestones which enhanced the development of more and more stringent specifications were the introduction of multi element atomic absorption (AAS), inductive coupled plasma - optical emission spectroscopy (ICP-OES), inductive coupled plasma - mass spectroscopy (ICP-MS) and finally the high resolution - inductive coupled plasma - mass spectroscopy (HRICP-MS).
Fig. Fig. 3
Technology Roadmap Quality Roadmap for Electronic Chemicals in Relation to Device Integration
Apart from the development
(Vison of 1989)
1000
of the analytical capabilities,
Metals (ppb) Particles (>0.5µm/ml)
100
technology road maps played an important part in the
10
development of specifications
1
and requirements. (Fig. 3) An
0,1
IBM road map from 1989, having the exceptional beauty of being valid up to now,
Source: IBM 1989
0,01
1
4
16
64
256
Linear Approximation - the Easy Way
clearly describes the relation between device integration (from 1 - 256 M) and the metallic impurity level as well as the particle level of the chemicals for the 1 MB Dram. For example a VLSI quality with metallic impurities around 50 ppb and particle levels of 250 P/ml was estimated to be sufficient. From this range a linear approach was taken to get to the 10 ppb level of metallic impurities for the 4 MB and a 1 ppb level of metallic impurities for the 16 MB Dram. Considering the limited analytical capabilities of 1989, the line, however, makes a small bend towards the 64 and 156 M Dram which according to this road map would require a 0.1 ppb level of metallic impurities in the chemicals. These predictions are astonishingly close to reality and today the 0.1 ppb quality is in fact applied for the manufacturing for the most advanced devices.
Published in Semiconductor FABTECH 13th editon
W. J. Sievert
Page 3
Electronic Chemicals TSD
From the chemical perspective the standard specifications like electronic grade (EG) or VLSI still somehow reflect the natural abundance of the individual elements in the environment. So the maximum values for elements like Iron, Calcium, and Sodium are
Fig. Fig. 4
specified considerably higher than
those
for
the
Electronic Chemicals Purity Roadmap
rare Metallic Impurities in Electronic Chemicals
elements or noble metals. In
10000
the course of the development
Non-Critical Chemicals
1000
and probably for the sake of the
natural
ppt
uniformity,
100
e.g. HF, H2 O2 , NH4OH
distribution of elements was
10
disregarded in the next step
1
and for a ULSI specification
Critical Chemicals
Analytical Capabilities
Reflecting 80 % of elements
0,1 1998
all metallic impurities are Technology
limited to a max of 10 ppb.
1999
2000
0.18µm
2001
2002 2003
0.15µm
0.13µm
2004
2005
The same approach is taken for the 1 ppb level (SLSI) and the 0.1 ppb level (XLSI). Here, however, already a conflict arises with the limited capability of the analytics so that for some elements larger tolerances are requested. This situation is illustrated in the electronic chemicals purity roadmap which next to the device related quality requirements also considers the development of the analytical capabilities. (Fig. 4)
Standardization of Specifications As the expected growth rates for wet chemicals are in line with the industry forecasts and new technology requires different chemistries and different specifications, the question is now: "How is this development accompanied and influenced by SEMI® standards?" It is interesting to note that the standard Electronic Grade and EG MOS quality level was already established in the suppliers industry in 1970. (Fig. 5) It took, however, 8 more years for SEMI® to establish and publish the SEMI® base standard in the book of standards. This base standard was then afterwards applied for more than 10 years as the only " SEMI® standard". After SEMI® had established its European office in Brussels and the European Chemicals and Gases Committee was formed, it was immediately recognized by the committee members that the SEMI® base standard did not at all reflect the requirements of the European semiconductor community. The group very soon came forward with a proposal to design and implement the VLSI quality level for key
Published in Semiconductor FABTECH 13th editon
W. J. Sievert
Page 4
Electronic Chemicals TSD
chemicals to get closer to the existing requirements of the
Fig. Fig. 5
Specifications Applied Implementation of Quality Levels into Standards and Industrial Production
customers and also to the state of art of electronic chemicals
Published in SEMI BOSS Implemented in Industry
manufacturing. The committee
10-500 ppb
EG/MOS
had to overcome a number of
10-100 ppb
VLSI
< 10 ppb
ULSI
< 1 ppb
SLSI
< 100 ppt
XLSI
different obstacles and a lot of convincement work had to be done. It finally was not before
2000
1998
1996
1994
1992
1990
1988
1986
1984
1982
1980
for the most important wet
1978
1976
1974
1972
1970
1994 that the VLSI guidelines
Breakthrough in 1990
processing chemicals passed the ballots and were implemented into the book of standards. In chemical manufacturing the VLSI quality level had been established already in 1981. It can definitely be regarded as one of the successes of the European Chemicals Committee that it initiated ideas to improve the standards for chemicals and consider higher quality levels. The breakthrough came in 1990 when the ULSI level was established in industrial manufacturing at the same time when the corresponding SEMI® standard (Grade 2) was published in the BOSS. After 1990 the work of the US Chemical and Guidelines Committee became very much accelerated and somehow visionary, already 2 years later in 1992 the SLSI (1 ppb) Guideline was released. The industrial implementation of this quality level at least for the key chemicals in Europe took another 4 years. It should be mentioned that the implementation of SLSI and XLSI production levels in the supplier industry utilized to a large extend the results of the European JESSI-Project. The final step was the release of the XLSI guideline (0.1 ppb) which for the key chemicals was achieved in 1998 in industrial production.
Production of Electronic Chemicals Just based on history EG and MOS Grade chemicals are just selected from technical grade materials produced in bulk by qualified manufacturers. (Fig. 6) Even the VLSI level can be achieved by mere selection based on the expertise of the analytical laboratories and an additionally applied filtration to remove the particles. For many years these two steps, selection of the material on the basis of analytical data and filtration to remove particulate impurities, were the only ones applied to generate electronic chemicals out of technical grade materials. With the introduction of the ULSI level of chemicals selection and filtration in some cases was not sufficient and additional purification technology had to be
Published in Semiconductor FABTECH 13th editon
W. J. Sievert
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Electronic Chemicals TSD
developed. It is one of the Fig. Fig. 6
Manufacturing vs Distribution
TechnicalGrade Material Produced in Bulk by Qualified Manufacturers
HP HP Production Production
UHP UHP Production Production
SLSI SLSI
inherent advantages of wet XLSI XLSI
processing chemicals that almost all of them can be
Selection, Selection, Purification Purification &&Filtration Filtration
ULSI ULSI
purified
by
applying
a
simple physical operation, such as distillation. In some
Selection Selection * * &&Filtration Filtration
VLSI VLSI
Selection Selection* *
E.G. E.G.and and MOS MOSGrades Grades
* few exceptions
Production Paths for Electronic Chemicals
cases
also
ion-exchange
technology is used and other
separation
technologies.
But
in
general, even most of the ULSI chemicals can be manufactured using selected technical materials. This scene changes completely with the introduction of the SLSI and later on even the XLSI quality levels. For SLSI levels all metallic impurities for example are limited to max. 1 ppb which is a problem for two types of metallic impurities. First, the metallic impurities which are inherent contaminants to the process and secondly, the metallic impurities which are the so-called ubiquitous elements, elements which are allover the place and might get into the product by random cross contamination. In the case of ultra high purity manufacturing to yield XLSI (0.1 ppb) products, the situation is even worse. In this field not only special equipment is required but also a complete isolation of the manufacturing areas from the environment is absolutely Fig. Fig. 7
Product Specifications
necessary.
Product Specifications Published in SEMI BOSS 1998 EG / MOS
VLSI
ULSI
SLSI
obvious
It
is
quite
that
the
XLSI
manufacturing
H3PO4 H2SO4
translate
HNO3 HF
Highest purity requirements for chemicals coming into contact with bare silicon
H2O2 HCl NH4OH
efforts
directly
into
manufacturing
costs.
While electronic grade,
BOEs
VLSI and to a certain
NH4F sol. IPA
extend also ULSI grade
NMP MeOH
products share almost the
NBA Acetone Acetic acid
same manufacturing and distribution
Solutions for Everyone
costs,
for
SLSI products there is
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Electronic Chemicals TSD
already a substantial increase while for XLSI products the manufacturing and distribution costs increase almost exponentially. So we will find very high costs at the high end. With the economic background mentioned before, semiconductor industry has become very much cost conscious during the past years. While, of course, also depending on company philosophy in the past the guideline - the purer the better - was applied, the situation has changed today. Improved knowledge about the impact of impurities on the performance or reliability of a semiconductor devices and the overall problem of manufacturing costs finally promoted the guideline that the highest purity requirements should be established only for those chemicals which come into direct contact with the bare silicon. (Fig. 7) This idea is very well reflected in the SEMI® book of standards where XLSI guidelines are published for the key chemicals Hydrofluoric acid, Hydrogen peroxide, Hydrochloric acid and Ammonium hydroxide. All of which are substantial ingredients even of most advanced cleaning technologies.
The Value of Standardization Considering the real production paths of electronic chemicals, the few existing standards and the vast variety of individual customer specifications, it seems like there has always been a great misunderstanding
Fig. Fig. 8
Number of Specs for HF and H2SO4
between
the involved parties. The specification data base of a
25
24
HF 40/50% H2SO4
20
13 9
5
4
0 MOS
VLSI
EG
than 750 specifications. With
4
2 0 E.G.
265
specifications. a total of mor
7 5
files
VLSI, 181 ULSI and 77 SLSI
11 10
supplier
specifications, 85 MOS, 147
16
15
15
typical electronic chemicals
ULSI
SLSI XLSI
The number of active specifications for HF 40/50 % and H2SO4 96 % seems to be related to the importance of the wet chemical
the number of chemicals used in
the
manufacturing
of
Semiconductor devices being somewhere (around
around 50
25
including
specialties), the total number of product specifications unacceptably high. Let us focus on two of the leading chemicals, Hydrofluoric acid - concentration range 40-50 % and Sulfuric acid 96 %. (Fig. 8) While Sulfuric acid as already mentioned before belongs to the commodity products, Hydrofluoric acid is definitely the key chemical of the specialty group. The broader application of Hydrofluoric acid also
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Electronic Chemicals TSD
for critical and advanced processes is reflected by the higher number of specifications. In the ULSI/SLSI range we find a total of 29 specifications for Hydrofluoric acid versus only 7 specifications for Sulfuric. Of course, the differences between the individual specifications are in many cases not very substantial if not to say almost negligible, Fig. Fig. 9
The Cost of Variety
but as the specifications are customer specific and in most
Cost model based on the consumption of HF 40-50 % ULSI (10 ppb) ppb) and SLSI (1 ppb) ppb) grades
cases part of the commercial Average consumption of 10 european wafer fabs Total consumption
40,000 l/a
40,000 l/a
400,000 l/a
400,000 l/a
Typical production lot size
10,000 l
Average lot size per order
2,500 l
10,000 l
contract, the suppliers have to accept them. The number of specifications not only lead to
Total number of lots
160
40
an enormous administrational
Average number of required analytical checks
120
50
effort, but also in many cases
Cost of analytical check on ULSI/SLSI level
1,300 $
1,300 $
Total analytical costs
162,000 $
67,500 $
to a significant waste of money. A model calculation (Fig. 9) for HF 40-50 %
Saving 58 % on analytical costs
ULSI and SLSI with typical production lot sizes of 10,000 liters and a total industrial demand of 400,000 liters per year by an average of 10 European wafer fabs, results in potential cost savings of 58 % on analytical costs. If standardization of the chemical specifications on let us say 4 relevant quality levels could be achieved, a number of cost saving issues could be implemented effectively. Larger production batches lead to lower warehousing costs and increased flexibility. The reduced number of specifications also reduces the number of part-numbers and labels as well as the necessity for individual safety stocks. What are the proposed actions? 1. Focus and implement 4 relevant quality levels, being in line with the actual situation in the production of high purity chemicals. 2. Reduce the number of specifications in line with the published SEMI® standards guaranteeing the availability of just the right material for the various levels of technology. 3. Increase production batch sizes and hence lower the cost of production and increase the flexibility in product delivery. 4. Standardize on packages and connect systems to enable cost saving material pools.
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Electronic Chemicals TSD
Apart from product specifications SEMI® standards have a lot more to offer for the supply chain for electronic chemicals. (Fig. 10) There are two fields of SEMI® activities which directly or indirectly supply value to the electronic chemicals business. 1.
SEMI® chemical specifications and guidelines
2.
SEMI® analytical methods
3.
SEMI® container guidelines
4.
SEMI® traceability standards
While SEMI® chemical specifications would be an issue for production and quality control the SEMI® traceability standards are a universal feature affecting production, quality control, transportation, storage, consumption and Fig. 10
finally waste management of
electronic
SEMI® Support Network
chemicals.
Unfortunately, there is still a
How can SEMI Standards affect the Supply Chain for Electronic Chemicals ?
limited overlap between the Production Production
areas
and
the
general
willingness
to
apply
Quality Control Quality Control
Transport Transport
standards developed in one of the four areas is still small.
Cost
SEMI SEMI Chem. Chem.Specs. Specs.
SEMI SEMI Anal. Anal.Methods Methods
Storage Storage
SEMI SEMI Container Container Guidelines Guidelines
Consumption Consumption
Waste Mgmt. Waste Mgmt.
SEMI SEMI Traceability Traceability Stand. Stand.
reduction
initiatives and globalization trends enhanced by global purchasing activities, however, have reactivated the activities and positively influenced the general acceptance. Economic pressure and the application of some common sense will eventually lead to a situation where few standardized products are delivered in customer specific packages thus bringing variety to a point where it makes sense. Several attempts during the past years to standardize containers and connections found themselves confronted with large obstacles mostly related to the historically grown infrastructure of older fabs. But also in this area it is again cost saving which may lead to a critical review of existing systems and the concentration on fewer optimized logistic systems.
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Electronic Chemicals TSD
Globalizing the Business with SEMI® Standards The development within the semiconductor industry during the past few years has clearly shown that the situation for chemical suppliers has substantially changed. (Fig. 11) Technological development together with economic pressure have led to the outphasing of older non-profitable systems and the implementation and development of new concepts of chemical manufacturing
and
distribution.
Among the prerequisites for a year 2000 chemical supplier we will find a trend from selection towards ultra high purity manufacturing. The use of performance packages and the turn from simple selling to integrated chemical management.
Fig. Fig. 11
Changing World for Chemical Suppliers
Prerequisites for Y2K Y2K Chemical Chemical Suppliers Suppliers ý From From Selection Selection towards towards UHP UHP Manufacturing ý Development of Performance Packages Packages ý From From Simple Simple Selling to to Integrated Chemical Chemical Management ý Product Stewardship for Customer Support Support in EHS Issues ý Provide Waste Management Management Support Support ý System Integration Integration and Management Management ý Strategic Alliances Alliances to to Close Gaps ý Global Global Presence and Support ý From From Chemical Chemical Supplier Supplier to to Solutions Provider Provider
Chemistry
Application
Safety
Customer Analytics
Packaging Logistics
Global opportunities for global players
Other activities required today and tomorrow
include
product
A Global Business Needs Global Support
stewardship for customer support in environmental, health and safety issues, waste management support, system integration and last not least the formation of global alliances. As the chemical supplier of the 80s and early 90s has now changed to become a solution provider, the adoption and application of standards is becoming an issue more important than ever before. Standardization is going to be the solution for cost effective materials management for the benefit of materials suppliers and semiconductor manufacturers.
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