Modification of showerhead in december 2014
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.
Comparison of continuous processes
| 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.
|
C4F8
|
SF6
|
O2
|
Coil
|
Time
|
Pres.
|
C4F8
|
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.
|
C4F8
|
SF6
|
O2
|
Coil
|
Time
|
Pres.
|
C4F8
|
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.
|
C4F8
|
SF6
|
O2
|
Coil
|
Time
|
Pres.
|
C4F8
|
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.
|
C4F8
|
SF6
|
O2
|
Coil
|
Time
|
Pres.
|
C4F8
|
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
|
|
