1. Pt-DSE Test Results Testing conducted by Kenneth Leedle
Results compiled by Yunhan Chen
Spring 2016

2. Pt-DSE Recipe 1
Recipe:
Same light and etch A steps as DSE FAT. No dep step. Etch A time is changed to 5 sec. Etch B time & conditions are below. No loop function.
300 SF6/ 5 C4F8/ 30 Ar/ 3000 ICP/ 60mT/10Vbias Etch B
Wafers:
Silicon wafer
Single crystal silicon wafer with 1.6mm 3612 photoresist and patterned with resolution mask.
Oxide wafer
1mm thermal SiO2 with 1.6mm 3612 photoresist and patterned with resolution mask.
Procedure:
Both patterned Silicon wafers and patterned Oxide wafers are etched using the above recipe.
For Silicon wafer, PR thickness is measured before and after etch using NanoSpec for getting PR etch rate. PR is then stripped and Si step height is measured for getting Si etch rate.
For Oxide wafer, Oxide thickness are measured pre and post etch in NanoSpec for getting Oxide etch rate.
Results:
PR Etch Rate
(nm/min)
Si Etch Rate
SiO2 Etch Rate (nm/min)
Si: SiO2 Selectivity
Ox:PR Selectivity
Si:PR Selectivity 66
8869 20
443.5
0.296
134.4

3. Cross section SEM image: Etch B Time: 120s
Patterned Si wafer: SCS wafer patterned with 1.6mm 3612 photoresist and resolution mask pattern.
17.5mm
7mm

4. For large opening areas, undercut is observed.
Comments:
For large opening areas, undercut is observed.
Isotropicity (ratio of lateral and vertical etching) is ~0.61.
Micro-loading effect is observed.
11.5mm
30mm
19mm
20mm

5. Pt-DSE Recipe 2
Recipe:
Same light and etch A steps as DSE FAT. No dep step. Etch A time is changed to 5 sec. Etch B time & conditions are below. No loop function.
300 SF6/ 5 C4F8/ 30 Ar/ 1500 ICP/ 60mT/10Vbias Etch B
Wafers:
Silicon wafer
Single crystal silicon wafer with 1.6mm 3612 photoresist and patterned with resolution mask.
Oxide wafer
1mm thermal SiO2 with 1.6mm 3612 photoresist and patterned with resolution mask.
Procedure:
Both patterned Silicon wafers and patterned Oxide wafers are etched using the above recipe.
For Silicon wafer, PR thickness is measured before and after etch using NanoSpec for getting PR etch rate. PR is then stripped and Si step height is measured for getting Si etch rate.
For Oxide wafer, Oxide thickness are measured pre and post etch in NanoSpec for getting Oxide etch rate.
Results:
PR Etch Rate
(nm/min)
Si Etch Rate
SiO2 Etch Rate (nm/min)
SiO2:Si Selectivity
SiO2:PR Selectivity
Si:PR Selectivity 45
6706 18
372.6
0.405
150.7

6. Cross section SEM image: Etch B Time: 120s
Patterned Si wafer: SCS wafer patterned with 1.6mm 3612 photoresist and resolution mask pattern.
8mm
20mm
20mm
17mm
6.2mm

7. For large opening areas, undercut is observed.
Comments:
For large opening areas, undercut is observed.
Isotropicity (ratio of lateral and vertical etching) is ~0.57.
Micro-loading effect is observed.
9.5mm
8.3mm
16.7mm
15.3mm

8. Pt-DSE Recipe 3
Recipe:
Same light and etch A steps as DSE FAT. No dep step. Etch A time is changed to 5 sec. Etch B time & conditions are below. No loop function.
150 SF6/10 O2/30 Ar/ 20mT/ 1500w ICP/100V bias Etch B
Wafers:
Silicon wafer
Single crystal silicon wafer with 1.6mm 3612 photoresist and patterned with resolution mask.
Oxide wafer
1mm thermal SiO2 with 1.6mm 3612 photoresist and patterned with resolution mask.
Procedure:
Both patterned Silicon wafers and patterned Oxide wafers are etched using the above recipe.
For Silicon wafer, PR thickness is measured before and after etch using NanoSpec for getting PR etch rate. PR is then stripped and Si step height is measured for getting Si etch rate.
For Oxide wafer, Oxide thickness are measured pre and post etch in NanoSpec for getting Oxide etch rate.
Results:
PR Etch Rate
(nm/min)
Si Etch Rate
SiO2 Etch Rate (nm/min)
Si:SiO2 Selectivity
Ox:PR Selectivity
Si:PR Selectivity
170.5
5637
51.5
109.5
0.3021
33.1

9. Cross section SEM image: Etch B Time: 120s
Patterned Si wafer: SCS wafer patterned with 1.6mm 3612 photoresist and resolution mask pattern.
20mm
6.5mm
11.5mm
4.6mm

10. For large opening areas, undercut is observed.
Comments:
For large opening areas, undercut is observed.
Isotropicity (ratio of lateral and vertical etching) is ~0.57.
Micro-loading effect is observed.
Charging in the SEM images is shown.
6.9mm
40mm
12.2mm

11. Horizontal: Vertical ER
Comparison
Summary of the 3 recipes:
Same light and etch A steps as DSE FAT. No dep step. Etch A time is changed to 5 sec. Etch B time & conditions are below. No loop function.
Recipe
Description
PR Etch Rate
(nm/min)
Si Etch Rate
SiO2 Etch Rate (nm/min)
Si:SiO2 Selectivity
Horizontal: Vertical ER
Si:PR Selectivity #1
300 SF6/ 5 C4F8/ 30 Ar/ 3000 ICP/ 60mT/10Vbias Etch B 66
8869 20
443.5
0.61 #2
 300 SF6/ 5 C4F8/ 30 Ar/ 1500 ICP/ 60mT/10Vbias Etch B 45
6706 18
372.6
0.57 #3
150 SF6/10 O2/30 Ar/ 20mT/ 1500w ICP/100V bias Etch B
170.5
5637
51.5
109.5