Comparison of continuous processes
The showerhead that distributes the process gasses inside the plasma source has been changed. With the new design the gas flow resistance in the gas line from MFC to plasma has been reduced. This has very little or no impact on processes that have a continuous gas flow - i.e. processes that are not switched. However, for processes with several gas flows that switch on and off, the switching from one gas flow to another will be much more well defined. This enables us to run Bosch processes with shorter cycles times. Shorter cycles times means smaller scallops and hence lower roughness and better control.
As stated, we believe that only switched processes will be affected by this change. Continuous processes such as Process C , Nano1.42 , isotropic etches, barc etches or the black silicon recipes are not believed to be noticeably affected.
Process
Before (Old showerhead)
After (New showerhead)
Name/Type
Description/parameters
Wafer ID
Comment
SEM images
Wafer ID
Comment
SEM images
Continuous black silicon recipe on blank wafer
15 mins, -10 degrees, 32 mtorr, 60 sccm SF6 , 55 sccm O2 , 70 W platen
S004592
Wafer centre
S004679
Wafer centre
S003900
Wafer edge
S004679
Wafer edge
Continuous isotropic silicon etch called isoslow7
1 minute, 10 degrees, 10 mTorr, 80 SF6 , 150 W coil, 3 W platen
S003900
4" wafer, 50 % load
S00XXX
No test yet
File:S00XX centre.jpg
Comparison of switched processes
Process A
Recipe
Name
Temp.
Deposition step
Etch step
Comments
Time
Pres.
C4 F8
SF6
O2
Coil
Time
Pres.
C4 F8
SF6
O2
Coil
Platen
Showerhead
Runs
Key words
Process A
Step1 11 cyc
20
4
25
200
0
0
2000
7.0
25(1.5s) 90>>150
0
350(1.5s) 550
5
2800
120>>140(1.5s) 45
Old
1
Step2 44 cyc
4
25
200
0
0
2000
7.0
25(1.5s) 150
0
350(1.5s) 550
5
2800
140(1.5s) 45
Step1 11 cyc
20
4
25
200
0
0
2000
7.0
25(1.5s) 90>>150
0
350(1.5s) 550
5
2800
120>>140(1.5s) 45
New
1
Profile improved
Step2 44 cyc
4
25
200
0
0
2000
7.0
25(1.5s) 150
0
350(1.5s) 550
5
2800
140(1.5s) 45
SOI
Recipe
Name
Temp.
Deposition step
Etch step
Comments
Time
Pres.
C4 F8
SF6
O2
Coil
Time
Pres.
C4 F8
SF6
O2
Coil
Platen
Showerhead
Runs
Key words
SOI etch
SOI
20
2
25
250
0
0
2000
3
30
0
400
40
2800
75 (0.025s, 75%)
Old
1
SOI
20
2
25
250
0
0
2000
3
30
0
400
40
2800
75 (0.025s, 75%)
New
1
OK
Process D
Recipe
Name
Temp.
Deposition step
Etch step
Comments
Time
Pres.
C4 F8
SF6
O2
Coil
Time
Pres.
C4 F8
SF6
O2
Coil
Platen
Showerhead
Runs
Key words
Process D
Original
0
2
20
150
0
0
2000
2.4
26
0
275
5
2500
35
Old
1
Original
0
2
20
150
0
0
2000
2.4
26
0
275
5
2500
35
New
1
New Process D
0
1
20
150
0
0
2000
3
26
0
275
5
2500
35
New
4
Large undercut
PrD01
0
1
20
150
0
0
2000
2.4
26
0
275
5
2500
35
New
2
PrD02
0
1.1
20
150
0
0
2000
2.4
26
0
275
5
2500
35
New
1
PrD-3
0
1
20
150
0
0
2000
2.5
26
0
275
5
2500
35
New
1
PrD-4
0
1
20
150
0
0
2000
2.2
26
0
275
5
2500
35
New
1
Best one so far!
Polysilicon etch
Recipe description
Name
Temp.
Deposition step
Etch step
Comments
Time
Pres.
C4 F8
SF6
O2
Coil
Time
Pres.
C4 F8
SF6
O2
Coil
Platen
Showerhead
Runs
Key words
Polysilicon etch
polySi etch DUV mask
30
2.3
10
50
0
0
600
5.0
10
20
60
5
400
40
Old
1
Slightly over-etching to ensure complete absence of grass
polySi etch DUV mask
30
2.3
10
50
0
0
600
5.0
10
20
60
5
400
40
New
1
Cpoly1
30
1.2
10
50
0
0
600
5.0
10
20
60
5
400
40
New
1
Very aggressive, unusable
Cpoly2
30
1.4
10
50
0
0
600
5.0
10
20
60
5
400
40
New
1
Cpoly3
30
1.6
10
50
0
0
600
5.0
10
20
60
5
400
40
New
1
Cpoly4
30
1.8
10
50
0
0
600
5.0
10
20
60
5
400
40
New
1
Cpoly5
30
2.0
10
50
0
0
600
5.0
10
20
60
5
400
40
New
1
