This PDF file contains the front matter associated with SPIE Proceedings Volume 12805, including the Title Page, Table of Contents, Attendee list, Author Biographies, and Welcome Note.

Lithography requirements for the Eighties

Recently, micro-photolithography has made significant progress which demands more precise control of small particles, not only in wafer processing but in photomask-making as well. Since control of small particles is basic and important to this technology, efficient environmental equipment should be developed for achieving this demand. In getting better yield in mask-making we have to consider not only the environment but also the raw material itself. In today's meeting, I would like to discuss the following items about photo-resist particles on photo plates. I. Particles and Mask Defects 11 . Particle Detection III. Problems in Determing Specifications.

Microlithography is truly an ubiquitous tool in the semiconductor industry. With the advent of electron-beam, X-ray and deep UV exposure systems, submicron features will be produced routinely. At the forefront of the technology is the application of microlithography to the fabrication of impeccable masks, capable of recreating perfect images to be transferred to the wafers. As a lithographic system, mask blank material must meet requirements which is in keeping with the advancing technology. In this paper, we will discuss some of the physicochemical characteristics of mask blank as a thin film system which consists of the coated resist and the sputtered chrome, using various techniques such as Auger spectroscopy, Gel permeation chromotography, ellipsometry and CARIS (constant angle reflection interference spectroscopy) . These techniques constitute the main part of the analytical test which guarantees controlled conditions for functional tests which will, in turn, guarantee successful outcome in a production mode.

This is a Panel Discussion on Analytical Testing of Blanks.

Users of chrome masks frequently specify low reflectance from the chromium surface and at the same time seek to minimize thickness of the chromium. It will be shown that specifying low reflectance results in a sacrifice in thickness. Options available in single and double layers using chromium and oxides of chromium will be discussed, and data from the optional structures will be presented.

To understand the parameters that determine adherence of a thin chromium film to a glass substrate, it is essential to describe the preparation of the substrate and the vacuum deposition system. The measurement of the film-to-glass bonding strength is difficult to quantitatively achieve. Consequently, functional use tests are employed to assure chrome-to-glass adherence.

Consistency of low reflective coatings and CD controls

The photoresist sensitivity indication method is not necessarily standardized. The present situation is that relative comparison is being effected by various firms through practical application. Therefore, in order to standardize future photoresist sensitivity and the indication method, I would like to touch on the several methods that have been employed so far for reference purposes.

I have been asked to discuss the topic, "Functional Control of C.D. Variance Through Resist Process and Etch Rates". I am sure there are a number of ways in which this topic could be approached; I have chosen the approach of trying to deliniate those parameters that are necessary to be controlled by the manufacturer in order to insure consistency and control of C.D. 1 s from the users' point of view.

Production yield of LSI devices mostly depends on the defect level of photomasks. A larger die size, higher packing density, and finer pattern size require photomasks, to have a lower defect density and a smaller defect size. Therefore, cleaning of masks to remove contamination and foreign particles from its surface has become more and more important to keep production yield of LSI in high level. Many cleaning methods have been proposed over the years and every mask manufacturer and wafer fabrication department has their own cleaning systems designed by themselves. However, new cleaning processes are still being developed due to the demand for higher levels of cleanliness every year and every month. Methods to remove contamination and foreign particles from a Cr mask are principally classified into two categories: a chemical way and a mechanical way. In the chemical way, acid solutions, oxidized solutions, alkaline solutions and organic solvents are used, depending on the nature and sort of contamination. In the mechanical way, there are several methods, such as scrubbing with a nylon brush, scanning a mask surface by pulsed high-pressure distilled water, organic solvents or chemical solutions, and so on. .Most of the current cleaning systems consist of both the chemical and mechanical methods. Today I would like to talk about damages or deterioration of Cr masks induced by the chemical and mechanical cleanings. First I will discuss the damage of Cr patterns due to rubbing after chemical cleaning treatment. We studied the dependence of the strength of the patterns upon the glass substrates and the chemicals which were used in the cleaning. The Cr films were coated by a sputtering method on five glass substrates, namely Q18, LE30, SL, SLW, and 7059. After making a Cr pattern on these substrates by a usual lithographic method, the plates were dipped in a chemical solution, and then subjected to a scrubbing test with a glass fiber bundle.

This panel discussion on functional testing took place at Bay Area Chrome Users Society Symposium 1981.