Lithography Tools

Lithography forms the backbone of a typical semiconductor device fabrication run. It enables us to ‘draw’/ ‘write’ micrometre or nanometre sized patterns, thereby defining the device dimensions.

In optical lithography, we ‘write’ using an ultraviolet (UV) beam, and pattern sizes can be as small as a few micrometres. Even smaller, nanometre-sized patterns can be written via e-beam lithography which uses a beam of electrons to ‘write’. In both cases, ‘writing’ is done on special light-sensitive (or electron-sensitive) materials known as resists. These are chemically processed after exposure (to light/ electron beam) to reveal the written pattern. Precise control over instrument, beam, chemicals and time is necessary to make any lithographic process a success.

IITBNF has multiple optical lithography tools with different pattern dimension limits. We also have a laser writer system that is capable of producing mask plates with micrometre-sized patterns for use in the optical lithography tools. The best resolution at IITBNF (< 20 nm) is achieved through our state-of-the-art e-beam lithography tool: Raith 150 Two. This tool can also be used for in-situ silicon dioxide and metal deposition using its electron beam induced deposition (EBID) feature. For both optical & e-beam tools, resist spinners dedicated to different types of resists are available with capabilities to process 2”, 4” & 8” wafers. All lithography tools are housed in separate clean rooms with tight control over temperature, humidity & lighting conditions.