MOCVD多功能在线监测探头的设计与实现

Design and Implementation of Multi-functional in situ Monitoring Probe Based on MOCVD

根据MOCVD在线监测设备的发展需要,设计了一种多功能在线监测探头,能够同时实现带反射率修正的三种红外辐射测温以及两个波长的反射率曲线监测,即:940nm/1 550nm双波长比色测温、940nm单色辐射测温、1 550nm单色辐射测温、940nm反射率曲线以及1 550nm反射率曲线监测.对探头的比色测温性能进行测试分析,并利用该探头对Si(111)衬底在我国自主研发的MOCVD系统中生长InGaN/GaN MQW结构蓝光LED外延片进行在线监测.结果分析表明:比色测温900℃~1 100℃范围内精度高于1℃;在700℃~1 100℃范围内重复性误差均在0.7℃内;距离容差性为2mm;三种红外测温最低量程均为435℃;并能有效避免探测孔有效面积变化的影响;由940nm反射率曲线得:n-GaN层的膜厚监测相对误差为3.6%.该设计能够同时实现MOCVD在线测温及膜厚测量,可为MOCVD在线监测设备开发提供参考.

According to the development needs of in situ monitoring equipment of MOCVD,a multifunctional in situ monitoring probe was designed,which can measure three infrared thermometry with reflectivity correction and reflectivity curve of two different wavelengths,namely：940nm/1 550 nm double-wavelength colorimetric thermometry,940 nm monochromatic radiation thermometry,1 550 nm monochromatic radiation thermometry,940 nm reflectivity curve and 1 550 nm reflectivity curve.The test measuring analysis was done for the properties of in-situ monitoring probe,the silicon（111） substrate growing blue light LED epitaxial wafer with InGaN/GaN MQW structure in homemade MOCVD system by using the probe,was monitored on-line.Result shows that the lowest range of three infrared thermometry is equally 435℃;the accuracy within 1℃ colorimetric temperature range from 900℃ to 1 100℃;the repeatability within 0.7℃ from 700℃ to 1 100℃;insentive to changes in height within 2 mm;and the method can avoid the affection of the effective area change of detector aperture.The relative error of n-GaN layer thickness measurement was 3.6% by analyzing 940 nm reflectivity curve.So it can be seen that MOCVD in situ thermometry and film thickness measurement can be achieved by the probe at the same time.The design can provide reference for the developing of MOCVD in situ monitoring device.