磷化銦活性離子蝕刻之研究及其接地洞之應用

Abstract

在很多半導體製程的應用，活性離子蝕刻因為有蝕刻速度快和優良的蝕刻 截面等優點而被廣泛地應用。並且對於矽、砷化鎵、磷化銦，和一些磊晶 系統，還有其它優點，例如：選擇性蝕刻,垂直截面,和異向性蝕刻。但是 也一些缺點,如些微的污染層,和組織破壞層。我們在這□將討論蝕刻時間 、壓力、輸出功率密度、氣體流量大小、和氣體組成等變數對 BCl3/SF6 ，SiCl4/SF6，CH4/H2，和 CF4/H2的離子蝕刻之影響。在 BCl3/SF6、和 SiCl4/SF6與 CH4/H2為混合氣體對於磷化銦蝕 刻的比較, CH4/H2 的混合 氣體有很好的表面形態，但是卻容易有高分 子膜堆積，且蝕刻速率較慢 。而在BCl3/SF6、SiCl4/SF6 的混合氣體中，二者有相似的性質，如較快 的蝕刻速率、和不佳的表面形態；在 Cl3/SF6、和SiCl4/SF6的混合氣體 中，蝕刻速率隨著功率密度增加而 急遽變快，且蝕刻速率在壓力50-60 mTorr時達到最高的速率，流量變 大也使其蝕刻速率變快。且在BCl3/SF6 中，在SF6佔0.6-0.8比例時有 最快的蝕刻速率。在 SiCl4/ SF6中，SF6 則佔0.2時有最快的蝕刻速率。對於BCl3/SF6和 SiCl4/SF6的混合氣體中 ，較快的蝕刻速率易留下粗糙的表面，此現象在較高流量和較大的功率密 度皆可觀察到。而壓力變愈小，使得離子撞擊能量變大反而留下粗糙的表 面。在本活性離子蝕刻研究中，我們亦對於磷化銦做各種條件的變數，找 出最快的蝕刻速率及最佳的表面形態。利用此研究的資料，我們將做出磷 化銦的接地洞，它的深度超過70-90um 。雖然活性離子蝕刻後，磷化銦將 留下粗糙的表面，但是在活性離子蝕刻後，我們將之在溶液中侵蝕出平滑 的表面，以此活性離子侵蝕和液態侵蝕，我們將能得到極佳具有垂直截面 和最佳表面的70-90um接地洞。 In this paper we report, we will have the study of reactive ion etching ( RIE ) of InP in BCl3/SF6, SiCl4/SF6,CH4/H2 and CF4 /H2 based gas mixtures, as a function of theplasma parameters such as etching time, pressure, power density,flow rate, and relative compositions. The etch rate of InP in BCl3/SF6 and SiCl4/SF6 based gas mixtures is higher than the etch rate in CH4/H2 and CF4/H2 mixtures. For BCl3/SF6/He or Ar and SiCl4/SF6/ He or Ar dischharges, they have similar properties. These etch rates become higher with increasing RF power density as observed from 0.162W/cm2 to 0.648W /cm2. The dependence of the etch rate on total pressurein the discharges is obvious. The maximum etch rates observed are around 50-60mTorr in a power density of 0.648W/cm2. The changes in the etch rates of InP with changes in the flow rate is big. The etch rates become with the increase of the flow rate under our operating For BCl3/ SF6 gas mixture, the increase in the etch rate is maximum when the SF6 fraction is up to 60-80% at the power of 0.405W/cm2. For SiCl4/SF6 mixtures, the etch rate will when the SF6 fraction is more than 20%. The etch parameters for InP was optimized to etch 70-90um via holes in this study. And after dry etching, the sample was wet chemical etched in the HCl-H2O2- H2O solution to remove the lips and surface roughness. Via holes of 70-90um depth was with good surface morphology and profile using this hybrid etch in this study.