Technologies & Processes
Over the course of a number of years, the RSC has set up a complete series of procedures that allow it to carry out all of the standard processes of silicon micromachining, supporting 100 and 150mm wafers and even chip formats.
The RSC uses various coating systems for photolithography, including positive, reverse image and dry resists, as well as special coatings, such as PMMA, Cytop® and the SU-8 family of negative resists. The latter permits coating thicknesses of several hundred micrometers (i.e. the “Poor Man’s LIGA Process”). The RSC has two mask aligners, which are also used for front-to-backside alignment. The RSC’s array of such equipment is completed by an (anodic) bonder for aligned bonding of silicon and Pyrex® wafers and a mask cleaner.
In wet chemistry, Piranha etch (Caro’s acid) and RCA techniques are used by the RSC to clean substrates. Resists can be stripped off before cleaning with removers or organic solvents. Wet chemical etching of either silicon or silicon compounds as well as metals can be performed as a batch process with up to 25 wafers at the same time.
IIn sputter and electron beam evaporation equipment a broad range of metal films – e.g. Al, Au, Cr, Ir, Ni, Pt, Ta, Ti, and TiW – can be deposited in the PVD line, while six dry etchers cover the full spectrum of dry etching equipment, including plasma ashers, RIE equipment with fluorine chemistry, and an ICP system for deep silicon etching.
The RSC also offers thermal oxidation as well as LPCVD and PECVD depositions for producing dielectric films like silicon dioxide and nitride, diamond-like carbon, and silicon carbide. Doped and undoped poly-silicon is deposited with a LPCVD technique.
For assembly, bonding and packaging techniques, the RSC has adhesive stations, die and flip chip bonders, plus various wire bonders on hand. Saws are also available for wafer dicing.
For characterizing processes and the structures that are produced, the RSC uses modern in-line metrology equipment. This includes, in particular, devices for analyzing wafer geometry, measuring stress, defining the thickness and topography of thin films both optically and mechanically (with white light interferometry, ellipsometry, profilometry), as well as recording the electrical properties with automatic wafer probers. The range of equipment is completed by an electron microscope.