Currently, extreme ultraviolet (EUV) lithography is the most promising candidate to generate patterns of high resolution (<30nm pitch), which are required for the 7nm node and below. In the last three decades, significant progress on multiple areas has brought the technology closer to insertion into high volume manufacturing. However, resist resolution and performance is one of the key factors that may define the limits for the use of EUV.
While characterization of resist as a function of resolution, line width (and edge) roughness and sensitivity is a common practice, recently, the focus has been on identification of random defects. As the resolution of the printed patterns approaches the molecular dimensions, random fluctuations in concentration of active components of the photoresist, and light intensity (photons) start to play a role in generation of such defects. As the economic cost for generation of EUV light is very high, the goal of the industry is to find materials and processes that suffer to a minimum extent from the light intensity fluctuations.
Example of a contact array printed at increasing contact size (De Bisschop, Proc. SPIE 9048, 2014)
In this project, you will investigate novel methods for inspection and characterization of the failures (or defects) when printing hole patterns of small dimensions with EUV. Initially, your work will focus on the study of different metrology techniques, to identify the best candidate to capture defects, at different steps of the process, over large areas. In a second stage, you will use different resist and stack materials, and optimize processing conditions as well as pattern designs, to understand the origin of random defects observed at small pitches as a means to minimize and, ultimately, eliminate them.
You will work together with a team of lithography specialists within an international environment using advanced tools at the leading-edge technology. Also, the interaction with the material suppliers for formulation of dedicated photoresist chemistries, equipment suppliers for processing or metrology and partnering universities will be part of your work. Your experimental work will be carried out in a modern 300 mm semiconductor cleanroom using the lithography clusters to coat and expose silicon wafers and metrology tools for material characterization. The results of your research will be presented to the imec partners, and are either published at international conferences, in peer reviewed journals or filed for patent.
Required background: The topic is best suited for students with a degree in chemistry, chemical engineering, nano-technology, materials science.
Type of work: 50% for preparation and execution of experiments, 30% for data analysis, 20% for literature study.
Supervisor: Guido Groeseneken
Daily advisors: Paulina Rincon, Sandip Halder
The reference code for this PhD position is STS1712-16. Mention this reference code on your application form.