Process Wafers Update

1
Process Wafers Update

• MatE/EE 129
• April 26th, 2004
• Mars Division

2
The Winning Team Members

• Tsu-Kai Teng Team Leader
• Kasem Tantanasiriwong Team Recorder
• Hua Qu Facilitator
• David Ahn Processing Engineer
• Kenneth Tseng Equipment Manager
• Michael Ra Processing Engineer
• Steven Diaz Safety Manager

3
Procedures

• Contact Photolithography
• Contact Area Etch
• Photo-Resist Strip
• Metallization

• Metal Pattern Photolithography
• Metal Etch
• Photo-Resist Strip (Al)

4
Mask 3 Contact Window Lithography
Etched Metal using acid etch
Used Plasma Etcher to etch away oxide
DI Rinse / Dry
Metallization Used Evaporator to deposit Al
Removed Remaining Photoresist
Mask 4 Metal Pattern Litho
Wafers now ready for Anneal
5
Mask 3 Contact Window Lithography
Oxide grown from oxidation
Resist
FOX
N-type
N-type
source
Source
Drain
Source
P-type

• Measure Oxide Thickness (Å) at Gate Windows
• Photolithography using Mask 3 (Exposed and
  developed)
• Inspected wafers for good line and cross
  resolution

6
Data Oxidation Thickness
Middle
Left
7
Plasma Etch (Etched oxide in S/D windows)
Gate Oxide
Resist
FOX
N-type
N-type
Drain
Source

• Parameters
• Etch Rate 400 A/min
• Use 20 overetch
• Etch time 2 min

P-type

• Applied Materials AME 8100 (Plasma Etcher)
• Flow of O2 - 8 SCCM
• Flow of CHF3 - 75 SCCM
• P 45 mT

8
Metalization

• Type
• - Evaporation
• Procedure
• Remove resist clean in Piranha dip, 30 sec
  rinse, and spin dry
• Use 20 clips Al to be evaporated and deposited on
  the wafer
• Measure sheet resistance of process wafers using
  four-point probe (set V 6.6 mV and read
  current)
• Calculate the Al thickness

Al
GOX
FOX
N-type
N-type
Drain
Source
P-type
9
Data Measure Al Sheet Resistance Rs and
thickness t

• Measurement tool Four Point Probe
• Voltage was set at 6.6 mV

10
Mask 4 Metal Pattern Photolithography

• Mask 4 Metal Mask
• Follow the steps of Photolithography
• Do Alignment Check after develop

Resist
GOX
Al
FOX
N-type
N-type
Drain
Source
P-type
11
Metal Etch
Resist
GOX

• Procedures
• Phosphoric, Nitric, Acetic(Galacial) acid and
  water
• Temp 45-50 C
• Individually stripped Al(1 wafer at a time)
• 2 DI rise spin dry
• Remove the resist

Al
FOX
N-type
N-type
Drain
Source
P-type
12
Data Metal Etch Time

• Each wafer was etched individually to ensure
  optimal conditions.
• We determined the etch time by visually looking
  at the wafer and making sure that the metal was
  all etched away.

13
Current Device State
GOX
Al
FOX
N-type
N-type
Drain
Source
P-type
14
The Final Steps

• Annealing (Rapid Thermal Processing)
• Testing

15
Any Questions???