Globalwafers Co., Ltd.

Other

Uwe Hermes

Sumeet S Bhagavat

Peter D Albrecht

Vandan Tanna

Carlo Zavattari

Carlos Zavattari

Methods for controlling the surface profiles of wafers sliced from an ingot with a wire saw include measuring an amount of displacement of a sidewall of a frame of the wire saw. The sidewall is connected to a bearing of a wire guide supporting a wire web in the wire saw. Based on the measured amount of displacement of the sidewall, a pressure profile for adjusting a position of the sidewall is determined by a computing device. Pressure is applied to the sidewall using a displacement device according to the determined pressure profile to control the position of the sidewall.

Methods and system for controlling a surface profile of a wafer

Methods for controlling the surface profiles of wafers sliced from an ingot with a wire saw include measuring an amount of displacement of a sidewall of a frame of the wire saw. The sidewall is connected to a bearing of a wire guide supporting a wire web in the wire saw. The measured amount of displacement of the sidewall is stored as displacement data. Based on the stored data, a pressure profile for adjusting a position of the sidewall is determined by a computing device. Pressure is applied to the sidewall using a displacement device according to the determined pressure profile to control the position of the sidewall.

It is the goal of the invention to provide an improved method and an improved apparatus to measure the diffusion length of minority charge carriers in semiconductors. In particular, the method should be easy to implement. The method should yield higher measurement accuracy. The data analysis should be easy. The apparatus should be easy to use. This goal is achieved using the following procedure steps: Application of periodically alternating light of different wavelengths (&#x3bb;) to the semiconductor sample (); Detection of the surface potential modulation caused by the application of the light, Adjustment of at least one of the light intensities (I) in such a manner that the surface potential modulation disappears; and Determination of the diffusion length (L) of the minority charge carriers from the adjusted light intensities. An apparatus consists of a first and a second monochromatic light source () with different wavelengths (&#x3bb;), means () to periodically apply the light of the first and second light source () to the sample (), means () to detect the surface potential of the sample (), means () to detect the modulation of the surface potential of the sample, means () to adjust the intensity of the light of at least one of the light sources () in such a manner that the modulation of the surface potential disappears and means to determine the diffusion length (L) of the minority charge carriers from the adjusted light intensities of the first and second light source (FIG.).

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Portland, OR, United States of America

Uwe Hermes