硅片直接键合中表面活化的研究

Investigation of Surface Activation in Silicon Wafer Direct Bonding

本文提出在直接键合前用等离子体活化硅片表面的方法。经活化后表面硅悬挂键明显增加,从而对羟基进行有效的化学吸附。低压气体放电等离子体主要通过离子轰击对硅表面赋能与活化,其活化效果与气体种类无关。温度通过热能对氧化硅表面有赋能与钝化作用,表面活化处理时温度不能超过临界点。850℃等离子体处理6分钟可得满意结果。已成功实现3英寸直径硅片之直接键合。所制成的高压MOS器件及0.8—3μm CMOS器件证实键合质量良好,未引入沾污及附加应力。

A novel prebonding plasma surface activation methed has been introduced. Surface silicon dangling bonds are significantly increased after surface activation which lead to effectively chemical adsorption of OH groups. Plasma produced by low pressure gas electric discharges can give energy to and activate the surface by ion bombardment. Therefore, activation effectiveness is independent of the gas used. Temperature can give energy to and passi-vate the oxide surface through thermal energy. Therfore, the activation temperature should not be over a critical point. Plasma treatment at 850℃ for 6' provides satisfactory results. 3' silicon wafers were succesfully bonded with this method. High voltage and 0.8-3μm CMOS devices have shown that the bonding introduces no contamination and extra stress, thus guarantee the bonding quality.