While a lithography process is used to ‘write’ micrometer/nanometer-sized patterns on a resist layer, a different technique is needed to transfer these patterns from the resist onto the main layer on the semiconductor wafer. Wet etching & dry etching are the most commonly used processes to achieve this goal.
Dry etch usually refers to material removal or patterning using a chemically reactive plasma. When a lithographically patterned sample is introduced into this plasma, ionic species bombard and chemically react with the exposed areas, while the resist-patterned areas are left protected. This method of pattern transfer from resist to the main layer using dry etch technique is anisotropic, whereas wet etch processes are typically isotropic in nature. As a result, dry etching is the preferred process for pattern transfer of small dimensions (≤ 10μm) and is often one of the critical steps in a semiconductor device fabrication run.
IITBNF has separate dry etch tools for silicon and III-V semiconductor samples to prevent material cross-contamination. A general purpose ion miller is used to dry etch any sample using a purely physical ion bombardment process. As part of our dedicated solar cell fabrication facilities, we also have an edge isolation tool necessary for electrically isolating the front and back sides of diffusion-doped crystalline silicon solar cells. Our facility also has plasma asher tools that are typically used to remove resist from a sample via a chemically reactive oxygen plasma.
The following table lists our dry etch tools along with their contamination category.
|1||ICPRIE (old)||Nanoelectronics Processing Lab (NanoE bldg, 1st floor)||clean|
|2||Plasma asher||Nanoelectronics Processing Lab (NanoE bldg, 1st floor)||gold contaminated|
|3||STSRIE||Micro1 Yellow Room||semi clean a|
|4||ICPRIE (New)||Nanoelectronics Processing Lab (NanoE bldg, 1st floor)||clean|
|5||AMAT - Ashing Chamber (Ch-D)||AMAT Lab||semi clean b|
|6||AMAT - Etch Chamber (Ch-A)||AMAT Lab||semi clean b|
|7||Ar-ion Milling||Nanoelectronics Processing Lab (NanoE bldg, 1st floor)||gold contaminated|
|8||Deep Reactive Ion Etching – Samco||NMPF Lab||gold contaminated|
|9||RIE-1C Plasma Etcher– Samco||NMPF Lab||gold contaminated|