Specific Process Knowledge/Characterization/Profiler/Optical Profiler (Sensofar) acceptance test

Results from the Optical Profiler (Sensofar) acceptance test

The acceptance test was performed in January 2012 by STInstruments and Sensofar together with Pernille V. Larsen @ Danchip and Berit G. Herstrøm @ Danchip.

This Table shows the accpetance criteria

'	Title	Sample description / measurement	Acceptance criteria
1	Patterned flat sample of silicon	Sample material: Patterned silicon substrate.	Depth 100±2 µm
		Trench depth with aspect ratio 1:10 on a 10 µm wide trench
2	Patterned flat sample of silicon.	Sample material: Patterned silicon substrate.	Depth 91±2 µm
		Trench depth with aspect ratio 1:11 on a 8 µm wide trench
3	Patterned flat sample of silicon	Sample material: Patterned silicon substrate	Depth 85±2 µm
		Trench depth with aspect ratio 1:13 on a 6.4 µm wide trench
4	Patterned flat sample of glass	3D profile of pattern etched down in a quartz sample.	Depth within ±1% from a standard profiler measurement and repeatability (3 successive measurements) within 0.1%
		Pattern size 20 µm x 20 µm, depth 500 nm
5	Flat sample of silicon with thick patterned oxide	Step height of patterned thick (10 µm) oxide on top of a silicon wafer.	Step height must be within ±3% of a SEM profile measurement.
		7 µm deep pattern, trench width 6 µm
6	Flat sample of silicon with thick layer of patterned polymer	Sample material: SU8 on silicon.	Height 69±2 µm
		Pillar heights of 69 µm with 25 µm between pillar edges
7	Free standing structure	Measure bow due to stress of a membrane.	Membrane bow repeatability of 5 successive measurement within 2%
		Membrane material: Si(2 µm)/SiO2(~1 µm)/Au(50 nm).
		Membrane size: honey comb structure approximately 150 µm in diameter.
		Bow < 500 nm
8	Stitching of large area	Stitching 4 mm x 4 mm on same sample as in 7. The area consists of many closed packed honey comb formed membranes.	Membrane bow must the same as on 7 within 2%
9	Narrow trenches and holes	Sample material: Patterned silicon substrate.	Depth 20±2 µm
		2.5 µm wide trench in silicon with a depth of 20 µm
10	Film thickness measurement of transparent thin film	Transparent thin film thickness of 28 nm SiO2 on Si	SiO2 thickness 28±1 nm
11	Measurements of multiple stacks	120 nm nitride on 110 nm oxide on a silicon substrate	Within ±2% on each layer from an ellipsometer measurement.
12	Film thickness measurements of transparent films on small structure	Sample material: Si with 1.5 µm patterned AZ-resist	Within ±1% from a standard profiler measurement.
		Measure thickness of AZ-resist on pillars of 50 µm in diameter
13	Roughness repeatability	Sample material: Si wafer with poly-silicon layer.	Repeatability within 0.2%
		3 successive measurements of the roughness

Results

Results of acceptance test no. 1, 2 and 3

Sample material: Patterned silicon substrate Measurement: Trench depth with aspect ratio 1:10, 1:11 and 1:13 on a 10µm, 8mm and 6.4µm wide trenches respectively Acceptance criteria:Depth 100±2 µm, 91±2µm and 85±2µm

It was done in two ways:

1. With confocal objective EPI 100x-N: See the results here
2. With Interferometric objective 50X DI: See the results here

Setting for methode no. 1: confocal

Recipe: Trench

• Operation mode: trench
  • + Raw smoothing confocal
  • + fine shift
• Objective: EPI 100X-N
• Z scan
  • Dual - bottom up
    • top: 8µm
    • Gap: 91µm
    • Bottom: 8µm
  • Speed factor: 1x
  • + Linear stage
• Threshold: 0.0%
• Light source
  • Levels: 2
    • 900 -> 60
    • Gain: default

Setting for methode no. 2: interferometric

We do not have a recipe for that but we used:

• Objective: Interferometric 50x DI
• Z scan: VSI
• Light souce: increased gain and contrast

Results of acceptance test no. 4

Sample material: Patterned fused silica.

Measurement: Depth of pattern

Acceptance criteria:Depth within ±1% from a standard profiler measurement and repeatability (3 successive measurements) within 0.1%

Standard profiler measurement:

It was done using interferometric measurements: Objective: DI 50x-N VSI z scan: 10µm Treshold: 1%

Results: It was repeated 10 Time The first measurement is shown here: