近单晶硅密度液体压缩系数精密测量方法

Precision measurement method of compression coefficient for density standard liquid close to single crystal silicon

近单晶硅密度液体(DSL-2329)广泛应用于单晶硅材料的高精密加工工艺中,其液体压缩系数准确测量对于单晶硅加工质量控制具有重要意义。为提高已有测量方法的精度,研究了一种基于单晶硅球静液悬浮原理的DSL-2329液体压缩系数测量方法。将单晶硅球放置于充满DSL-2329液体的密闭容器内,通过改变DSL-2329液体的温度和静压力可以进行液体密度的微量调节,从而实现单晶硅球在液体中的静液悬浮。对于一个单晶硅球而言,可以在不同液体温度和静压力条件下实现静液悬浮,其中温度和静压力满足线性模型,测量出这个线性常数就可以计算出液体压缩系数。设计了单晶硅球静液悬浮测量系统,实现水浴温控系统在3 h之内可以保持在±1.0×10-4℃的范围内,通过PID控制系统调节静压力实现单晶硅球的静态悬浮。实验数据表明,由三溴丙烷和二溴乙烷组成的DSL-2329液体压缩系数为5.15×10-10Pa-1,验证了单晶硅球静液悬浮测量方法的有效性。

The density standard liquid at 2 329 kg/m3 close to single crystal silicon （DSL-2329） is widely used in the precise machining of silicon single crystal material, and the accurate measurement of the volume compression coeffi- cient of this liquid plays an important role in the quality control of silicon single crystal machining. To improve the measurement accuracy of the existing measurement method, a measurement method based on hydrostatic suspension principle is discussed to determine the compression coefficient of DSL-2329 liquid. The single crystal sphere is im- mersed into a sealed vessel full of DSL-2329. The density of the liquid can be adjusted through changing the liquid temperature and static pressure, and the hydrostatic suspension of the silicon single crystal sphere is achieved. The sil- icon single crystal sphere could be suspended at different temperatures and static pressures, where the temperature and static pressure parameter comply with a linear mathematical model. The compression coefficient is calculated using the data of temperature and static pressure at the suspension state. A hydrostatic suspension experimental system was de- signed with maximal temperature control error ± 1.0 ×0 -4 oC within 3 h, and the static floating of the silicon single crystal sphere could be achieved through static pressure regulation with a PID control system. In the experiment, the mixture of 1,2,3-tribromopropane and 1,2-dibromoethane was used as the DSL-2329 liquid. The compression coeffi- cient was measured, and its value is 5.15 × 10 10 Pa-1, which verifies the effectiveness of the proposed measurement method and experimental system.