DEVELOPMENT OF INTERNAL STRESS MEASUREMENT SYSTEM IN SEMICONDUCTOR USING INFRARED RAY

我们研制了一种小型的半导体应力测量系统，该系统基于红外线合成光弹方法。利用可见光实现超声可视化的合成光弹方法，由于红外线通过半导体传输，可以应用于该系统。系统开发的主要工作可分为两部分。第一部分是建立红外合成光弹方法应用的光学装置。第二种是基于光弹条纹级的常规标定方法不能适用的应力标定方法，我们尝试了一些光源、滤光片和透镜，确定在红外光学系统中使用大功率灯泡作为红外光源，半导体板作为滤光片。为了从光弹图像中标定出应力，我们制作了一台双加载机，由于该系统原理上不能使用四分之一波长板，而半导体板在拉伸载荷作用下太脆而不能形成条纹，因此需要加载一块环氧板来制作光弹性条纹。双加载机实现了对应力测量的校准。利用该系统对硅片中的残余应力进行了测量，得到的残余应力为2 Mpa，其测量精度为-lt；正负-0.1 Mpa。利用该系统可以测量其他半导体中的残余应力分布。

We developed a small stress measurement system for semiconductors, which is based on a synthesized photoelastic method using infrared rays. The synthesized photoelastic method developed for ultrasonic visualization using visible rays could be applied to the system because infrared rays transmit through semiconductors.Main work of the system development can be divided into two parts. First part is to set an optical arrangement for synthesized photoelastic method application with infrared rays. Second one is a calibration method of stress evaluation because normal calibration method based on a photoelastic fringe order can not be applied.We tried some light sources, light filters and lens, and then determined to use a high power bulb as a infrared light source and a semiconductor plate as a light filter in the infrared optical system.In order to calibrate the stress from the photoelastic image, we made a double loading machine, in which a epoxy plate is loaded to make a photoelastic fringe because a quarter wavelength plate can not be used in this system principle and a semiconductor plate is too brittle to make a fringe under tensile loading. The double loading machine enabled to the calibration of the stress measurement. Sensitivity of a silicon semiconductor was about 1/10 value, compared with that of epoxy material.We measured residual stress in a silicon wafer using this system and obtained the values of 2 MPa as the residual stress with accuracy of <plus-minus>0.1 MPa. The residual stress distribution in other semiconductors could be measured using this syste