Quantum Computers - NanoJapan
Quantum Computers A. Walker; Y. Shimizu; Y. Shiren; Y. Kawamura; J. Ozawa; K. Itoh Building The All-Silicon Model
Results
＊The depth profiles after TED annealing (950oC, 30min) ＊
29Si
Scored and DC Corrected 28Si
MOS FET Model MOS FET functionality:
2411724800
gate
ー －
1,000,000,000
oxide
75366400
10,000,000
Nanoscale
2355200
+
1,000,000 73600
100,000 10,000
positive
Pentium 4
channel B diffusion
2,300
1,000
Pentium 2
100
+
+
+
10
1970
1980 1/2/00
1990 1/3/00
2000 1/4/00
2010
-Adaptation versus Innovation: Creating new transistor designs or reinventing old ones
The All-Silicon Model
10
15
- When voltage is applied to the gate above the oxide layer, positive boron atoms accumulate between the source and drain, allowing the flow of current - Gate voltage therefore controls the switch between transistor binary states
10
19
10
18
10
17
40keV 2x1013 cm-2 B→Si, in N2, O2 200
10
16
10
15
40keV 7o/ 23o 2x1013 cm-2 B→Si 0
200
furnace
Boron Diffusion Three branches of diffusion studied 1. The influence of the B ion implantation damage on TED Tilt 7o/ Rotation 23o or 7o/0o
2. The influence of OED during initial annealing
7o Tilt
400
600
800
OED increases B ion diffusion
- Boron diffusion must be controlled for nanoscale MOS FET to work
(Oxygen Enhanced Diffusion)
800
n o t including O 2
- The binary state becomes fixed; it is independent of gate voltage
(Transient Enhanced Diffusion)
600
D epth ( n m )
- Nanoscale channels carry current as a result of B diffusion
0o Tilt
400
in clu d in g O 2
Affect of presence of 02
3. The influence of SiO2/Si interface during annealing With or without SiO2(～20nm) films on the Si surface
10
-12
10
-13
10
-14
10
-15
10
-16
10
-17
＊ TED annealing (950oC, 30min)＊ with SiO2
B Diffusivity (cm2 s-1)
- In the coming years, it is projected that exact positioning of 29Si and precise NMR readout will allow development of the first working All-Silicon Quantum Computer
16
＊The depth profiles after TED annealing (950oC, 30min)＊
- Annealing purifies transistors, but it also causes B atoms to diffuse
- Nuclear Magnetic Resonance (NMR) is used to locate each 29Si atom and control its spin direction - A phosphorus atom at the opposite end of the chain allows NMR to differentiate between multiple chains
+
3. An oxide layer is added above the channel between the source and drain
Nanoscale challenge:
- 29Si atoms are positioned regularly in chains in a 7-Tesla magnetic field - A 2-Tesla Ni/Fe magnet at one end of the chain individualizes the spin of each 29SI atom
B diffusion
n-type Si wafer
1/5/00
-Quantum Challenge: Progressing from micro to nanoscale transistors presents new physical and methodological hurdles
positive
+
1 1/1/00
+
2. Positively charged B atoms are implanted in a neutral Si wafer at the source and drain
2 -1
100,000,000
10
Amount of B ion implantation damage has no correlation with TED
B Concentration (cm-3)
++
10,000,000,000
17
o
)
drain
10
o
7 /0 o o 7 /2 3
-3
－－ －ー
source
18
0
1. A current source and drain are connected to a silicon wafer
Boron Diffusivity (cm s )
- Gordon Moore’s Law: Market transistors need to progressively decrease in size by a factor of two every two years Number of Transistors on a Component Circuit
10
D e p th (n m )
(Metal Oxide Semiconductor Field Effect Transistor)
Background
19
-3
Boron Concentration (cm
Ni/Fe Magnet
B Concentration (cm-3)
Phosphorus
10 )
1. Manual scoring of 28Si chips produces regular step arrays 2. Subsequent DC heating corrects nanoscale imperfections 3. Controlled exposure to natural Silicon allows chains of 29Si to form on the apex of each step
Boron Concentration ( cm
Abstract
Silicon microchips have continued to grow progressively smaller to meet the demands of a competitive market. The next step in development will send the chips from micro-order to nano-order, giving rise to new and challenging complications. Here, two methods are explored to develop such technology. The first involves molecular beam epitaxial (MBE) growth of isotopically controlled Si-based quantum computers. Manual scoring of isotopically pure 28-Si chip followed by kink-up DC correcting and subsequent 29-Si addition leaves equally distributed lines of 29-Si with controllable nuclear spin. Capping the lines on one end with Ni/Fe magnets and on the other end with P atoms, individual spin can be read out and controlled using NMR. The second method involves modifying the traditional Metal Oxide Semiconductor Field Effect Transistor (MOS FET) for successful nano-scale operation. Excessive boron diffusion causes unwanted digital logic stage switching in nano-order MOS FET, so methods to control boron diffusion, transient and oxygen enhanced diffusion, are studied.
without SiO2 R. B. Fair (1975) J. S. Christensen (2003)
40keV 7o/ 23o 2x1013 cm-2 B→Si, in N2, O2 0.75
0.80
0.85 -1
1000/T (K )
0.90
0.95
[1] R. B. Fair, J. Electrochem. Soc, 122, 800 (1975) [2] J .S. Christensen et al., APL, 82, 2254 (2003)
Lack of surface SiO2 on Si substrate increases B ion diffusion
Results
＊The depth profiles after TED annealing (950oC, 30min) ＊
29Si
Scored and DC Corrected 28Si
MOS FET Model MOS FET functionality:
2411724800
gate
ー －
1,000,000,000
oxide
75366400
10,000,000
Nanoscale
2355200
+
1,000,000 73600
100,000 10,000
positive
Pentium 4
channel B diffusion
2,300
1,000
Pentium 2
100
+
+
+
10
1970
1980 1/2/00
1990 1/3/00
2000 1/4/00
2010
-Adaptation versus Innovation: Creating new transistor designs or reinventing old ones
The All-Silicon Model
10
15
- When voltage is applied to the gate above the oxide layer, positive boron atoms accumulate between the source and drain, allowing the flow of current - Gate voltage therefore controls the switch between transistor binary states
10
19
10
18
10
17
40keV 2x1013 cm-2 B→Si, in N2, O2 200
10
16
10
15
40keV 7o/ 23o 2x1013 cm-2 B→Si 0
200
furnace
Boron Diffusion Three branches of diffusion studied 1. The influence of the B ion implantation damage on TED Tilt 7o/ Rotation 23o or 7o/0o
2. The influence of OED during initial annealing
7o Tilt
400
600
800
OED increases B ion diffusion
- Boron diffusion must be controlled for nanoscale MOS FET to work
(Oxygen Enhanced Diffusion)
800
n o t including O 2
- The binary state becomes fixed; it is independent of gate voltage
(Transient Enhanced Diffusion)
600
D epth ( n m )
- Nanoscale channels carry current as a result of B diffusion
0o Tilt
400
in clu d in g O 2
Affect of presence of 02
3. The influence of SiO2/Si interface during annealing With or without SiO2(～20nm) films on the Si surface
10
-12
10
-13
10
-14
10
-15
10
-16
10
-17
＊ TED annealing (950oC, 30min)＊ with SiO2
B Diffusivity (cm2 s-1)
- In the coming years, it is projected that exact positioning of 29Si and precise NMR readout will allow development of the first working All-Silicon Quantum Computer
16
＊The depth profiles after TED annealing (950oC, 30min)＊
- Annealing purifies transistors, but it also causes B atoms to diffuse
- Nuclear Magnetic Resonance (NMR) is used to locate each 29Si atom and control its spin direction - A phosphorus atom at the opposite end of the chain allows NMR to differentiate between multiple chains
+
3. An oxide layer is added above the channel between the source and drain
Nanoscale challenge:
- 29Si atoms are positioned regularly in chains in a 7-Tesla magnetic field - A 2-Tesla Ni/Fe magnet at one end of the chain individualizes the spin of each 29SI atom
B diffusion
n-type Si wafer
1/5/00
-Quantum Challenge: Progressing from micro to nanoscale transistors presents new physical and methodological hurdles
positive
+
1 1/1/00
+
2. Positively charged B atoms are implanted in a neutral Si wafer at the source and drain
2 -1
100,000,000
10
Amount of B ion implantation damage has no correlation with TED
B Concentration (cm-3)
++
10,000,000,000
17
o
)
drain
10
o
7 /0 o o 7 /2 3
-3
－－ －ー
source
18
0
1. A current source and drain are connected to a silicon wafer
Boron Diffusivity (cm s )
- Gordon Moore’s Law: Market transistors need to progressively decrease in size by a factor of two every two years Number of Transistors on a Component Circuit
10
D e p th (n m )
(Metal Oxide Semiconductor Field Effect Transistor)
Background
19
-3
Boron Concentration (cm
Ni/Fe Magnet
B Concentration (cm-3)
Phosphorus
10 )
1. Manual scoring of 28Si chips produces regular step arrays 2. Subsequent DC heating corrects nanoscale imperfections 3. Controlled exposure to natural Silicon allows chains of 29Si to form on the apex of each step
Boron Concentration ( cm
Abstract
Silicon microchips have continued to grow progressively smaller to meet the demands of a competitive market. The next step in development will send the chips from micro-order to nano-order, giving rise to new and challenging complications. Here, two methods are explored to develop such technology. The first involves molecular beam epitaxial (MBE) growth of isotopically controlled Si-based quantum computers. Manual scoring of isotopically pure 28-Si chip followed by kink-up DC correcting and subsequent 29-Si addition leaves equally distributed lines of 29-Si with controllable nuclear spin. Capping the lines on one end with Ni/Fe magnets and on the other end with P atoms, individual spin can be read out and controlled using NMR. The second method involves modifying the traditional Metal Oxide Semiconductor Field Effect Transistor (MOS FET) for successful nano-scale operation. Excessive boron diffusion causes unwanted digital logic stage switching in nano-order MOS FET, so methods to control boron diffusion, transient and oxygen enhanced diffusion, are studied.
without SiO2 R. B. Fair (1975) J. S. Christensen (2003)
40keV 7o/ 23o 2x1013 cm-2 B→Si, in N2, O2 0.75
0.80
0.85 -1
1000/T (K )
0.90
0.95
[1] R. B. Fair, J. Electrochem. Soc, 122, 800 (1975) [2] J .S. Christensen et al., APL, 82, 2254 (2003)
Lack of surface SiO2 on Si substrate increases B ion diffusion
