Laser Reflectance Interferometry for In Situ Determination of Silicon Etch Rate in Various Solution

Abstract

The etch rate of crystalline silicon in liquid solutions has been measured in situ by laser reflectance interferometry. A simple method has been developed which allows accurate real-time observation of the etch rate as a function of etching parameters and sample characteristics. The method is demonstrated by measurements on (100) single crystal silicon samples etched in tetramethylammonium hydroxide solutions. Etch rates in the range of 0.05-1 m/min have been measured. Some examples of the optical power reflected from silicon samples during etching are presented and the parameters which may influence the accuracy of the etch rate measurements are discussed. Interpretation of the interference pattern of the reflected power can be complicated due to sample thickness variations and surface roughness. To investigate the impact of surface topography on the detected optical power, three simulation models have been developed.) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 128.172.-231.48 Downloaded on 2015-03-14 to IP ) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 128.172.-231.48 Downloaded on 2015-03-14 to IP

Optical interferometry and photoacoustics as in-situ techniques to characterize the porous silicon formation: a review

“…In the case of PSi growth is possible to integrate an optical system to the electrochemical cell. Thus, during the PSi formation, new films and interfaces appear producing changes in the optical path [13]. The behavior of R, T, and polarization of the light contain information about the etch rate, optical constants, interface roughness, and porosity [16,42].…”

“…The main techniques reported to study the in situ formation of PSi by electrochemical etching in hydrofluoric acid(HF) media are: in situ Fourier transform infrared spectrometry (FTIR) [10,11], optical interferometry [12][13][14][15][16][17] optical scattering [19,20], and photoacoustics [21][22][23][24][25].…”

“…This means, that during the PSi formation, it is possible to follow the changes in the thickness, roughness, and porosity by using light interferometry because the optical path changes continuously and multiple interfaces where the light can be reflected appear. This methodology and the mathematical model were reported in [12][13][14][15][16][17][18].…”

Exploiting Anisotropy for In Situ Measurement of Silicon Etch Rates in KOH Solution

“…With a comparable setup Steinsland et al studied etching of the three important crystallographic orientations of silicon, i.e., ͑100͒, ͑110͒, and ͑111͒, and developed a simulation model. 17 Surface roughness and gas evolution can be a problem with this approach.In this paper we show how one can exploit the anisotropy of silicon etching to develop two rather simple methods for in situ measurement of the etch rate of certain faces of the semiconductor. With an aligned mask V-grooves defined by ͑111͒ facets are etched in a ͑100͒ substrate.…”

“…With a comparable setup Steinsland et al studied etching of the three important crystallographic orientations of silicon, i.e., ͑100͒, ͑110͒, and ͑111͒, and developed a simulation model. 17 Surface roughness and gas evolution can be a problem with this approach.…”