Modeling and Measurement/Ellipsometry

Wednesday, April 12, 2000 1:30 PM in Room Sunset

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1:30 PM PJS-temp-1 Automated Film Thickness and Optical Constants Measurement of Color Filter Arrays Used in CMOS Imagers
M.F. Tabet (Nanometrics Inc.); M.G. Fereres (Tower Semiconductor, Israel); F. Yang (Nanometrics Inc.)
Red, green, and blue colored photoresist films are used as color filter arrays for image producing semiconductor devices. Thickness and optical properties of these films is critical and must be controlled. A combination of spectroscopic ellipsometry and spectroscopic reflectometry was used to measure the thickness and optical constants of these films. A research grade variable angle of incidence spectroscopic ellipsometer (VASE) was used to accurately measure the optical constants of the three colored films. The optical constants of each one of the films were then modeled through the use of the parametric semiconductor dispersion model, which allows us to measure both thickness and optical constants. These models were then imported onto a production metrology tool, which measures both visible ellipsometer and reflectometer data from the same location on the silicon wafer and simultaneously determined the thickness and optical constants of the colored films. This measurement performed on a production metrology tool takes approximately 10 seconds.
1:50 PM PJS-temp-2 Recent Advances in Quantitative Chemical Analysis of Optical Coatings
S. Romani, H. Kheyrandish (MATS, United Kingdom)
Chemical analysis of thin films require (a) quantification for accurate measurement of the composition of the major elements as well as any dopants or impurities (b) high sensitivity for detection and measurement of ultra low levels of the dopants or impurities and (c) good depth resolution in depth profiling applications for resolving very thin layers or the distribution of various elements within the layer(s).[PARA][PARA]This paper will provide an overview of the various microprobe surface analysis techniques (e.g. AES, XPS, SIMS, SNMS and RBS) for chemical analysis of thin films. It will also compare their relative merits AND limitations in terms of sensitivity and quantification.[PARA][PARA]Special attention will be paid to Sputtered Neutral Mass Spectrometry (SNMS), and we will discuss its merits for quantitative analysis of a wide range of optical coatings. The paper will show examples of analysis multilayer oxides and high sensitivity quantitative measurement of a number of elements (e.g. Li, Na, K, Ca and Al) in SnO2 and SiO2 amongst others.[PARA][PARA]Finally, factors effecting depth resolution in sputter depth profiling techniques will be discussed in terms of interfacial mixing and ion induced roughening effects. We will discuss new approaches to minimize these effects by using low energy beams at optimum angles of incidence.[PARA].
2:10 PM PJS-temp-3 Infrared Ellipsometry Study of Sio@sub 2@ Films : Relationship between Lo Mode Frequency and Porosity.
A. Brunet-Bruneau, S. Fisson, B. Gallas, G. Vuye, J. Rivory (Laboratoire d'Optique des Solides, France)
The interest in amorphous SiO@sub 2@ thin films for various applications in microelectronics or in optical coatings persists. The evaporation by electron gun, usually used for optical coatings, is a deposition method which leads to porous films. When the films are exposed to air, the porous microstructure allows a penetration of water molecules, which is followed by a silica hydrolysis and a stress relaxation. Dense materials can be prepared using ion assisted deposition, but isolated pores in the silica network could remain. @paragraph@ In this work, for any pores connectivity we present a method for evaluating the pore volume fraction in silica films. A series of silica films, evaporated by electron gun with or without ion bombardment, has been studied using visible and infrared ellipsometry. From infrared ellipsometric data, we have calculated the film dielectric function and have deduced the actual TO and LO mode frequencies, which are, by this method, film thickness independent. @paragraph@ We show that the study of both TO and LO mode frequencies brings independent information on the film microstructure. It is widely accepted that the TO mode frequency (near 1075 cm@super -1@) varies mainly with the density of the silica matrix. On the other hand, the LO mode frequency (near 1245 cm@super -1@), whose behavior has not been often examined, is relatively insensitive to the densification of the silica matrix; its variation is essentially due to change in porosity. We have established a general relation between LO frequency and porosity in silica films. In the case of films with pores largely connected, the evaluation of the pore volume fraction from the LO frequency is compared with that obtained from the analysis of the large absorption band near 3300 cm@super -1@ (H-OH and Si-OH stretching absorption band).