Precise Control of Thickness Uniformity in Mo/Si Soft X-Ray Multilayer

Yadan, 朱亚丹 Zhu; Ming, 方明 Fang; Kui, 易葵 Yi

doi:10.3788/aos201131.1131001

Cited by 1 publication

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“…Chung presented a similar method for controlling the thickness of single-crystal Si wafers in the aqueous tetramethylammonium hydroxide [17]. Zhu et al explored the thickness uniformity control of a single layer to obtain uniform optical properties of a large-area soft X-ray multiplayer [18]. In this research, a laser probe is used as the tool for the thickness measurement of Si wafers.…”

Section: Introductionmentioning

confidence: 99%

Laser-based Thickness Control in a Double-Side Polishing System for Silicon Wafers

Zhu

Mei

Zhu

et al. 2020

Sensors

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Thickness control is a critical process of automated polishing of large and thin Si wafers in the semiconductor industry. In this paper, an elaborate double-side polishing (DSP) system is demonstrated, which has a polishing unit with feedback control of wafer thickness based on the scan data of a laser probe. Firstly, the mechanical structure, as well as the signal transmission and control of the DSP system, are discussed, in which the thickness feedback control is emphasized. Then, the precise positioning of the laser probe is explored to obtain the continuous and valid scan data of the wafer thickness. After that, a B-spline model is applied for the characterization of the wafer thickness function to provide the thickness control system with credible thickness deviation information. Finally, experiments of wafer-thickness evaluation and control are conducted on the presented DSP system. With the advisable number of control points in B-spline fitting, the thickness variation can be effectively controlled in wafer polishing with the DSP system, according to the experimental results of curve fitting and the statistical analysis of the experimental data.

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Section: Introductionmentioning

confidence: 99%