STS Pegasus 4/Processes/LNF Si Thinning 1
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| About this Process | |
|---|---|
| Process Details | |
| Equipment | STS Pegasus 4 |
| Technology | RIE |
| Material | Silicon |
| Mask Materials | not typical |
| Gases Used | SF6 |
LNF Si Thinning 1 is an SF6 based process intended for isotropic thinning of Si wafers for device release. It does not have high uniformity, but has good selectivity to other materials.
Contents
Procedure
Follow the standard operating procedure.
Parameters
| Parameter | Dep* | Etch |
|---|---|---|
| ICP Power | 0 W | 2800 W |
| Bias Power (HF) | 0 W | 5 W |
| Pressure | 100 mTorr | |
| SF6 Flow | 0 sccm | 450 sccm |
| O2 Flow | 0 sccm | 45 sccm |
| Ar Flow | 200 sccm | |
| Time | 40 s | 20 s |
| Chuck Temperature | 20°C | |
* Dep step is used as a cooldown (no plasma) for temperature control.
Capabilities
Etch rate
This recipe is only characterized for blanket etching (no mask, 100% loading) on a 100 mm wafer. Etch rate will change for different loading areas or sample sizes.
| Material | Etch Rate | Uniformity |
|---|---|---|
| Silicon | 3.2 µm/min | 2.1% |
Mask selectivity
This recipe is intended for blanket etching, however a few common materials are included, as they may be used as an etch stop or for certain unusual processes.
| Material | Etch Rate | Uniformity |
|---|---|---|
| Silicon dioxide | 38 Å/min | 9% |
| Silicon nitride | ? | ? |
| SPR 220 | 130 Å/min | 26% |
Etch profile
The etch profile is not characterized, as it is intended as a blanket etch. However, the process is considered isotropic.
Limitations
Etch length
This etch is designed to generate minimal heat and includes a cooldown cycle, therefore it is capable of running for long periods of time without risking damage to samples. However, the standard operating procedure should be followed: in particular, for etches longer than 60 min, you must create a helpdesk to work with a tool engineer. It is not sufficient to simnply split the etch into multiple segments.
Etch depth
For any etches that require a carrier wafer per the guidelines in the SOP, it is required that 100 mm samples are mounted to a 150 mm wafer and processed in the STS Pegasus 6 to prevent particulate from falling onto the chuck.
