Extreme Ultra Violet (EUV) light has a wavelength of 13.5 nm and is being used to make the most advanced semiconductor chips.   To be able to increase throughput and pattern fidelity allowing smaller and smaller features, the sensitivity of the resist needs to improve and the resulting line edge roughness become smoother.  At Illinois we have an EUV source to work with TOK’s new developments in resist chemistry.

After computer chips are etched, there is some residue remaining that needs to be removed.  A specially designed cleaning solution is used at this point.  As etch recipes change, and Moore’s Law progresses, the demands on this solution increase.   Our work is to create and test new formulations for new etch chemistries and dimensions.

Photoresists not only have to be developed easily by being sensitive to light, but they also have to have etch selectivity.   While silicon, or oxide are being etched, the photoresist needs to remain intact.   Our work is to test the etch selectivity of a variety of photoresists and understand how changes to the resist chemistry effect that selectivity.

IPI has a state-of-the-art TEL ICP etching system, scaled to 6” wafers.   We are diagnosing all the properties of the plasma – density, electron temperature, energy distribution of the electrons, species produced, radical densities, etc.—ultimately as a function of position and of time.  This work will lead to a better understanding of the plasma and how various knobs on the tool effect the plasma parameters.

Adding a laser which can illuminate an entire field on a wafer while not illuminating another field can lead to improving uniformity of etching.  By controlling the polarity of the laser, it is also possible to direct that added energy to the top or to the bottom of the pattern.  This DEAL process can also allow damage-free etching.

A microwave plasma is able to make pure single-sheet and multiple-sheet-3D graphene at high rates and high purity.   Microwave engineering combined with appropriate zonal gas delivery can dramatically effect both rates and purity.  These processes are modeled and diagnosed through fast-frame cameras and spectroscopy in an effort to maximized production of the desired product.

Graphene made in a plasma can be decorated with metal and then dissolved in that material.  Copper infused in this manner gains in conductivity and hardness.  These changes are akin to iron becoming steel by adding a small amount of carbon.  Even 5% improvements of Cu or Al’s conductivity would justify replacement of every transmission line in the country.   Work on improving these properties are ongoing.

An ASML EUV-lithography tool hits molten Sn droplets with a high power laser.  Some of the Sn becomes very energetic and is deposited on the mirrors which collect the EUV light, ruining their reflectivity.  The best way to clean that Sn is to convert it to stannane – SnH₄. Stannane is an unstable compound and little is known about its properties.  We plan to make stannane and study it before it decomposes. Interactions with the pumps’ walls and components will be one of the main topics.