Michael Patra

Professional interests

I am a scientist at Carl Zeiss SMT GmbH, the world market leader for lithography optics. This page is a summary of some of the things I have been doing in the past.

Computer chips are produced by means of photolithography. An enlarged copy of the structures that are to be produced are put on a photomask, more frequently referred to as a reticle. The structures on this mask are then imaged onto a silicon wafer that has been coated with a photosensitive material.

Animation eines Scanners zur photolithographischen Belichtung von Mikrochips](https://upload.wikimedia.org/wikipedia/commons/c/c2/Stepper.gif

Freeform illumination

It can be shown that the direction of the radiation impeding onto the photomask is relevant for the resolution of an optical system, i.e., for the smallest size of structures than can be transfered onto the wafer. On the other hand, the contrast of the image also depends on that direction. The best compromise can be a very complex distribution of energy of directions. One possibility to supply such illumination distributions is to use a micro-mirror array: every small mirror of such an array deflects part of the total radiation into a desired direction. Integrating over all the mirrors of the array gives a freeform illumination with a large number of degrees of freedom.

drawing of a micro-mirror array sketch of an illumination system of a lithographic projection apparatus WO2010102649

I have been one of the developers of the FlexRay illumination system. It is the commercially most successful lithography system offering freeform illumination.

Free-electron laser

The resolution limit depends on the wave length of the radiation as well. The lower the wave length, the smaller the structures that can be created. For this reason EUV lithography is at this moment starting to be used for the production of computer chips. Unfortunately it is very complicated to create photons of such low wave length using traditional light sources: Plasma sources are complex and not particularly reliable — there is the inherent risk of damage to the lithography system by small amounts of tin and other materials that can escape from the light source. A potential alternative for the future is the free-electron laser (FEL).

layout of a free DE102014205579A1

A free-electron laser is not particularly difficult in itself — its most important components linear accelerators and undulators are well-etablished pieces of technology. Due to very fundamental reasons, a free-electron laser is, however, very large even if it needs to supply only a moderate amount of radiation. It thus is sensible to use a single free-electron laser for supplying the radiation for several lithography systems. I worked on the question of how to distribute the radiation in an equal and very stable way. This task is complicated by the need to avoid the risk of introducing speckle — an inherent risk when lasers are being used.

Several lithography systems with a single free-electron laser DE102014226920A1

Smart glasses

As many people are wearing glasses anyway, it might be advantageous to use these glasses to supply additional information to the wearer. Such glasses are referred to as smart glasses. The Google Glases are a deterring example as they make the wearer look a bit like a cyborg.

Google Glass with frame

I was part of a development team for novel smart glasses. They look like normal glasses, as all electronic components are integrated into the frame. Furthermore, as no camera is included, there are no issues with privacy protection — for understandable reasons, people don't liked being filmed with a camera all the time.

smart glasses WO2015158828

Inventions

As you can see from my patent applications, I am quite active as an inventor. I am trained in general creativity techniques but also am certified at the TRIZ-level 3 by MaTRIZ. Many of my invention are based either on more general creativity techniques or on the more technically oriented [TRIZ approaches]https://en.wikipedia.org/wiki/TRIZ). Transforming an invention into a strong patent application is no easy task, however — patent attorneys are very well trained in this aspect, yet they usually lack the specific background to fully understand an invention. I can help filling this gap as I have a diploma in patent law.

Urkunde MaTRIZ Level 3 Zertifikat als Patentreferent