InP晶片位错密度的测量与分析

Measurement and Analysis of the EPD on InP Single Crystal Wafers

采用湿法腐蚀方法研究了HCl,H3PO4和HBr等不同腐蚀液在显示<100>InP晶片位错中的作用,及腐蚀温度、腐蚀时间、光照条件等因素对腐蚀速率和腐蚀效果的影响,最后统计3英寸(1英寸=2.54 cm)<100>InP晶片位错密度分布,分析其位错产生原因。经过实验表明,单一的HCl或H3PO4腐蚀剂无法显示出<100>InP晶片的位错坑,而单一的HBr能够很好地显示出四方形的位错坑。在<100>InP晶片的混合位错腐蚀液中,HBr占主导作用,HCl及H3PO4起辅助作用。在腐蚀过程中提供光照或者提高腐蚀温度都可以明显提高腐蚀速率。在光照条件下,半导体会激发出空穴-电子对,在半导体表面增加载流子可以有效提高反应速率,从而提高腐蚀速率。化学反应速率常数k随温度升高呈指数升高,所以提高腐蚀温度可以有效提高腐蚀速率。InP晶片位错主要是由晶体内部热应力引起的。

Using the wet chemical etching method, the effects of HC1, H3PO4 and HBr etchants on the display of the dislocations on 〈100〉 InP single crystal wafers were studied, and the effects of the etching temperature, etching time, illumination condition on the etching rate and etching effect were also studied. The etch pit density （EPD） on 3-inch （1 inch = 2.54 cm） 〈100〉 InP single crystal wafers was measured, and the origin cause of the dislocations was ana- lyzed. The experimental results show that dislocation pits on 〈100〉 InP single crystal wafers can＇t be found only using HC1 or H3PO4 etchant, while the quadrate dislocation pits can be found clearly using HBr etchant only. In the mixed dislocation etchants of %100~ InP wafers, HBr plays a dominant role, while HC1 and H3 PO4 are catalyst. The etching rate is improved obviously with illumination and higher temperature during the etching process. With the illumination, the hole-electron pairs are exci-ted in semiconductors. The reaction rate is improved through increa- sing the carriers on the semiconductor surface, and the etching rate is improved. The chemical reactionrate constant k can increase exponentially with the increase of the temperature, therefore, the reaction rate can be improved effectively by improving the etching temperature. The dislocations of InP single crystal wafers are mostly induced by the crystal internal thermal stress.