STS Pegasus 4/Processes/LNF Si Thinning 1
LNF Si Thinning 1 (previously known as LNF Si Thinning Etch) 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.
|About this Process|
|Equipment||STS Pegasus 4|
|Mask Materials||not typical|
|Gases Used||SF6, O2|
Follow the standard operating procedure.
|ICP Power||0 W||2800 W|
|Bias Power (HF)||0 W||5 W|
|SF6 Flow||0 sccm||450 sccm|
|O2 Flow||0 sccm||45 sccm|
|Ar Flow||200 sccm|
|Time||40 s||20 s|
* Dep step is used as a cooldown (no plasma) for temperature control.
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.
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.
|Silicon dioxide||38 Å/min||9%|
|Silicon nitride||150 Å/min||11%|
|Low stress nitride||120 Å/min||10%|
|SPR 220||130 Å/min||26%|
The etch profile is not characterized, as it is intended as a blanket etch. However, the process is considered isotropic.
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.
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.