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我厂生产的3CTK50A～1000A类型的快速可控硅元件,硅片氧化前的抛光工序过去一直采用氧化镁(MgO)机械抛光工艺。随着国民经济的发展,我厂快速可控硅的产量大幅度增加,原有的抛光工艺已经不能满足生产的要求。在毛主席革命路线的指引下,我车间抛光工序全体同志学习兄弟厂的先进经验,采用优选法,经过多次试验,把原有的氧化镁机械抛光改为铬离子抛光工艺,已在生产中应用了两年多,效果良好,现将我们在实践中的几点体会介绍如下。 我们理解铬离子抛光的原理是利用颗粒小,硬度大,棱角锋利的Cr_2O_3颗粒作机械研磨的微粒,研磨后产生的机构损伤层随时又被从重铬酸铵离解出来的Cr_2O_7腐蚀掉,因此既能达到预期的抛光效果,又使硅片表面的晶格较为完整。铬离子腐蚀的机理如下: 3Si+2Cr_2O_7~-+16H~+=3SiO_2+6Cr+8H_2O 铬离子抛光既有机械抛光的平整度好,无桔皮状腐蚀坑的优点,又有化学抛光结构损伤较小的优点,而且速度快,成本低,掌握好了,是一种多快好省的抛光方法。 我们刚开始采用铬离子抛光时,虽然硅片表面质量有了改进,但抛光速度太慢,仍不适应生产的需要,当时我们分析,影响抛光速度的主要因素是研磨剂Cr_2O_3(三氧化二铬)与腐蚀剂(NH_4)_2Cr_2O_7(重铬酸铵)搭配不当,于是先固定H_2O与Cr_2O_3的配比,来选择
I produced the factory 3CTK50A ~ 1000A type of SCR devices, wafer oxidation before the polishing process has been the use of magnesium oxide (MgO) mechanical polishing process. With the development of the national economy, the output of our rapid SCR has greatly increased. The original polishing process can no longer meet the requirements of production. Under the guidance of Chairman Mao’s revolutionary line, all the workers in the polishing workshop of our factory studied the advanced experience of Brother Factory and adopted the optimization method. After many trials, the original magnesium oxide mechanical polishing was changed to the chromium ion polishing process, which has been applied in the production More than two years, the effect is good, now we experience in the practice described below. We understand the principle of chromium ion polishing is the use of small particles, hardness, sharp angular Cr_2O_3 particles for mechanical grinding of the particles, after grinding the body damage layer at any time from being dissociated from ammonium bichromate Cr_2O_7 erosion, so both To achieve the desired polishing effect, but also to the silicon surface of the crystal lattice more complete. The mechanism of chromium ion corrosion is as follows: 3Si + 2Cr_2O_7 ~ + 16H ~ + = 3SiO_2 + 6Cr + 8H_2O Chromium ion polishing has the advantage of good mechanical properties and no corrosion of orange peel corrosion pits, as well as chemical polishing structural damage Small advantages, but also fast, low cost, good grasp, is a more efficient way to polish. When we first started to use chromium ion polishing, although the surface quality of the wafer has been improved, but the polishing speed is too slow, still not suited to the production needs, we analyzed the main factors affecting the polishing speed is abrasive Cr2O3 (chromium oxide ) And corrosive (NH_4) _2Cr_2O_7 (ammonium dichromate) with improper, so first fixed H_2O and Cr_2O_3 ratio, to choose