TYPICAL PROCESS FLOW SHEET Starting Material: 6"diameter, (100)silicon(n-type, 1014 cm-3), 700 um thick Steps 1) RCa clean Grow SiO2 Desired Thickness=250 A, Temp=1000 C, Time=20 minutes Ambient= Dry 02. This oxide is to minimize channeling during the implant step Implant back-side of wafer to improve back-side contact. Energy =100 keV Dose=5x105 cm-2, Element=Phosphorus 4) Timed etch in BOE (Buffered Oxide Etch) to remove oxide Rate=1000 A/min,Time 35 seconds. (Includes 20 second over-etch to ensure completion. 5) RCA clean 6) Grow SiO2 Thickness=1000A, Temp=950 C, Time=20 minutes Ambient=Wet O2. This oxide is used to mask the implants in steps 9 and 12 7) Photolithography- Mask #1. Dark Field 8 Timed etch in BOE (Buffered Oxide Etch) to pattern oxide Rate=1000 A/min, Time 80 seconds. End this process step with a photoresist strip Implant front-side of wafer with a n-type dopant. Energy =50 keV, Dose=2. 6x1014 cm-2 Element= Arsenic 10) Photolithography- Mask #2. Dark Field 11) Timed etch in BOE(Buffered Oxide Etch)to pattern oxide Rate=1000 A/min, Time 80 seconds. End this process step with a photoresist strip 12) Implant front-side of wafer with a p-type dopant. Energy =20 keV Dose=5x1012 cm-2 Element=Boron 3) Timed etch in BOE (Buffered Oxide Etch) to remove all oxide Rate=1000 A/min 80 seconds 14) RCA clean 15)Grow SiO2 Thickness=1000 A, Temp =1100 C, Time=40 minutes Ambient=Dry 02. To facilitate hand calculations of the diffusion, we assume the Si/SiO2 boundary is stationary when determining junction depths 16) Dopant Drive-In. Temp=1100C, Time =1. 2 hours, Ambient=N2 17) Deposit LPCVD Polysilicon. The poly will be in-situ doped with Phosphorus Thickness 5000 A Temp =600C. (We neglect diffusion during this deposition. 18) Photolithography -Mask #3. Clear field 19) Etch polysilicon in SF6 plasma ( Assume infinite selectivity with oxide ) End this process step with a photoresist strip 20) Strip polysilicon from back-Side in SF6 plasmaTYPICAL PROCESS FLOW SHEET Starting Material: 6" diameter, (100) silicon (n-type, 1014 cm-3), 700 µm thick Steps: 1) RCA clean 2) Grow SiO2. Desired Thickness = 250 Å, Temp = 1000°C, Time = 20 minutes, Ambient = Dry 02. This oxide is to minimize channeling during the implant step. 3) Implant back-side of wafer to improve back-side contact. Energy = 100 keV , Dose = 5x1015 cm-2, Element = Phosphorus. 4) Timed etch in BOE (Buffered Oxide Etch) to remove oxide. Rate = 1000 Å/min, Time = 35 seconds. (Includes 20 second over-etch to ensure completion.) 5) RCA clean 6) Grow SiO2. Thickness = 1000Å, Temp = 950°C, Time = 20 minutes , Ambient = Wet O2 . This oxide is used to mask the implants in steps 9 and 12. 7) Photolithography - Mask #1. Dark Field 8) Timed etch in BOE (Buffered Oxide Etch) to pattern oxide. Rate = 1000 Å/min, Time = 80 seconds. End this process step with a photoresist strip. 9) Implant front-side of wafer with a n-type dopant. Energy = 50 keV, Dose = 2.6x1014 cm-2, Element = Arsenic. 10) Photolithography - Mask #2. Dark Field 11) Timed etch in BOE (Buffered Oxide Etch) to pattern oxide. Rate = 1000 Å/min, Time = 80 seconds . End this process step with a photoresist strip. 12) Implant front-side of wafer with a p-type dopant. Energy = 20 keV , Dose = 5x1012 cm-2, Element = Boron. 13) Timed etch in BOE (Buffered Oxide Etch) to remove all oxide. Rate = 1000 Å/min, Time = 80 seconds . 14) RCA clean 15) Grow SiO2. Thickness = 1000 Å, Temp = 1100°C, Time = 40 minutes Ambient = Dry O2 . To facilitate hand calculations of the diffusion, we assume the Si/SiO2 boundary is stationary when determining junction depths. 16) Dopant Drive-In. Temp = 1100°C, Time = 1.2 hours, Ambient = N2 . 17) Deposit LPCVD Polysilicon. The poly will be in-situ doped with Phosphorus. Thickness = 5000 Å Temp = 600°C. (We neglect diffusion during this deposition.) 18) Photolithography - Mask #3. Clear field. 19) Etch polysilicon in SF6 plasma. (Assume infinite selectivity with oxide.) End this process step with a photoresist strip. 20) Strip polysilicon from back-side in SF6 plasma. 3