In the silicon wet etching process, the "pseudo-mask" formed by the hydrogen bubbles generated during the etching process is the reason causing high surface roughness and poor surface quality. Based upon the ultrasonic mechanical effect and wettability enhanced by isopropyl alcohol (IPA), ultrasonic agitation and IPA were used to improve surface quality of Si (111) crystal plane during silicon wet etching process. The surface roughness Rq is smaller than 15 nm when using ultrasonic agitation and Rq is smaller than 7 nm when using IPA. When the range of IPA concentration (mass fraction, wt%) is 5-20%, the ultrasonic frequency is 100 kHz and the ultrasound intensity is 30-50 W/L, the surface roughness Rq is smaller than 2 nm when combining ultrasonic agitation and IPA. The surface roughness Rq is equal to 1 nm when the mass fraction of IPA, ultrasound intensity and the ultrasonic frequency is 20%, 50 W and 100 kHz respectively. The experimental results indicated that the combination of ultrasonic agitation and IPA could obtain a lower surface roughness of Si (111) crystal plane in silicon wet etching process.

中文翻译：

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超声搅拌和表面活性剂添加剂对碱性KOH溶液中Si（111）晶面表面粗糙度的影响。

在硅湿法蚀刻工艺中，在蚀刻工艺期间产生的氢气泡形成的“伪掩模”是导致高表面粗糙度和不良表面质量的原因。基于异丙醇（IPA）增强的超声力学效应和润湿性，在硅湿法刻蚀过程中，采用超声搅拌和IPA改善Si（111）晶面的表面质量。当使用超声搅拌时，表面粗糙度Rq小于15nm，而当使用IPA时，Rq小于7nm。当IPA浓度范围（质量分数，wt％）为5-20％，超声频率为100 kHz，超声强度为30-50 W / L时，结合超声搅拌，表面粗糙度Rq小于2 nm和IPA。当IPA的质量分数为1时，表面粗糙度Rq等于1 nm，超声强度和超声频率分别为20％，50 W和100 kHz。实验结果表明，在硅湿法刻蚀过程中，超声搅拌和IPA的结合可以获得较低的Si（111）晶面表面粗糙度。