为实现垂直腔面发射激光器(VCSEL)氧化孔径的精确控制,对垂直腔面发射激光器湿法氧化工艺的氧化速率规律进行了实验研究。在不同的温度下对垂直腔面发射激光器样品进行湿法氧化,氧化后采用扫描电镜(SEM)对氧化层不同氧化深度处生成物组成进行了微区分析。结果表明在不同氧化深度处氧化生成物各元素的组分含量不同,尤其氧元素的组分含量差别较大。分析和讨论了氧化不同阶段的反应类型和反应生成物,并建立了氧化速率随时间变化的数学模型,推导出在湿法氧化过程中,氧化速率随时间按指数规律变化,指出在一定的温度下,氧化时间越长,氧化速率越趋于稳定;适当降低氧化温度,延长氧化时间可提高氧化工艺的可控性与准确性。
The law of wet oxidation rate is studied with experiments in vertical-cavity surface-emitting lasers (VCSEL) in order to accurately control the oxidation aperture. Wet oxidation experiments are carried out upon the samples of VCSELs at different temperatures, and micro-probe analyses are made at different oxidation depth by scanning electron microscope (SEM). It shows that the element content in oxidation products is different at different oxidation depth especially that of the oxygen element. The reaction style and the oxidation products are analyzed and discussed, and a mathematical model on oxidation rate vs time is built up. The oxidation rate is derived, which is in an exponential growth law during the wet oxidation. At constant temperature, the oxidation rate becomes more and more steady with increase the oxidation time. The oxidation process quality can be improved by lowering the oxidation temperature and prolonging the oxidation time appropriately.