本文選題：單晶碳化硅(SiC) + 芬頓反應(yīng)　； 參考：《廣東工業(yè)大學(xué)》2017年碩士論文

【摘要】：單晶SiC作為第三代半導(dǎo)體材料,因具備禁帶寬度大、擊穿電場(chǎng)高、熱導(dǎo)率大、電子飽和漂移速率高、抗輻射能力強(qiáng)等優(yōu)越性能,是固態(tài)光源和電力電子、微波射頻器件的“核芯”,在半導(dǎo)體照明、新一代移動(dòng)通信、能源互聯(lián)網(wǎng)、高速軌道交通、新能源汽車、消費(fèi)類電子等領(lǐng)域有廣闊的應(yīng)用前景。作為重要應(yīng)用之一,用于外延工藝基片的單晶SiC表面要求超光滑、無缺陷、無表面/亞表面損傷,表面粗糙度達(dá)到Ra≤0.3nm,以滿足外延膜生長(zhǎng)的需要。但單晶SiC的硬度高(莫氏硬度9.2)、硬脆性大、化學(xué)穩(wěn)定性好等原因,高效超精密平坦化加工SiC難度極大,嚴(yán)重制約了SiC半導(dǎo)體器件的應(yīng)用和發(fā)展。本文通過芬頓羥基自由基(·OH)檢測(cè)試驗(yàn)、SiC氧化反應(yīng)試驗(yàn),驗(yàn)證了芬頓反應(yīng)能夠氧化單晶SiC。芬頓反應(yīng)過程能夠生成氧化性極強(qiáng)的氧化劑—羥基自由基,羥基自由基能夠與單晶SiC發(fā)生化學(xué)反應(yīng)生成氧化層。對(duì)氧化層進(jìn)行XPS物質(zhì)屬性分析發(fā)現(xiàn),該氧化層為Si O2。氧化層的納米壓痕試驗(yàn)表明,Si O2氧化層的硬度和模量遠(yuǎn)小于原始SiC表面,采用磨粒加工可以很容易去除這層軟質(zhì)氧化層,證實(shí)了基于芬頓反應(yīng)的化學(xué)機(jī)械拋光方法能夠?qū)尉iC進(jìn)行超光滑平坦化加工。從化學(xué)影響因素角度,針對(duì)芬頓反應(yīng)生成的羥基自由基濃度及其對(duì)SiC化學(xué)機(jī)械拋光的影響進(jìn)行了系統(tǒng)的實(shí)驗(yàn)研究。比較了羥基自由基濃度對(duì)單晶SiC氧化效果的影響,研究了芬頓試劑組份(催化劑種類、Fe2+濃度、p H值、H2O2濃度等)對(duì)芬頓反應(yīng)生成羥基自由基的規(guī)律及其對(duì)SiC化學(xué)機(jī)械拋光的影響。研究發(fā)現(xiàn)羥基自由基濃度越高,SiC表面生成的氧化層越厚,SiC化學(xué)機(jī)械拋光效果越好、拋光效率越高。芬頓試劑組份為0.02wt.%FeSO4、5wt.%H2O2、p H3時(shí),芬頓反應(yīng)生成的羥基自由基濃度較高,并能極大促進(jìn)SiC化學(xué)機(jī)械拋光,獲得了表面粗糙度Ra0.187nm的超光滑表面。從拋光工藝角度,對(duì)磨料種類、磨料濃度、磨粒粒徑、拋光壓力、拋光轉(zhuǎn)速等工藝參數(shù)進(jìn)行了單因素實(shí)驗(yàn),研究對(duì)材料去除率和拋光效果的影響規(guī)律。結(jié)果發(fā)現(xiàn)選擇硅溶膠磨料、磨料濃度為20%、磨粒粒徑為50nm、拋光壓力為0.02Mpa、拋光轉(zhuǎn)速為60r/min時(shí)的加工效果最佳,能夠獲得表面粗糙度Ra≤0.3nm的超光滑表面。在研究基于芬頓反應(yīng)SiC化學(xué)機(jī)械拋光的化學(xué)因素和工藝參數(shù)的基礎(chǔ)上,分析了基于芬頓反應(yīng)的化學(xué)機(jī)械拋光的材料去除過程,探究了拋光墊的特性、磨損、接觸變形的作用機(jī)理及其對(duì)SiC拋光效果的影響,建立了基于芬頓反應(yīng)的單晶SiC化學(xué)機(jī)械拋光材料去除模型,揭示了化學(xué)機(jī)械拋光機(jī)理。芬頓反應(yīng)生成的羥基自由基能與單晶SiC發(fā)生化學(xué)反應(yīng)生成一層軟質(zhì)易去除的Si O2氧化層,氧化層在磨粒的機(jī)械摩擦作用下被去除,化學(xué)和機(jī)械的交替作用最終實(shí)現(xiàn)SiC表面的材料去除。
[Abstract]:As the third generation semiconductor material, single crystal SiC is a solid state light source and power electronics because of its large band gap, high breakdown electric field, high thermal conductivity, high electron saturation drift rate, strong radiation resistance and so on. The "core" of microwave RF devices has a broad application prospect in semiconductor lighting, new generation mobile communications, energy Internet, high-speed rail transit, new energy vehicles, consumer electronics and other fields. As one of the important applications, the surface of single crystal SiC used in epitaxial substrate is super-smooth, non-defect, no surface / sub-surface damage, surface roughness is less than 0.3nmRa to meet the needs of epitaxial film growth. However, the single crystal SiC has high hardness (Mor hardness 9.2%, hard brittleness, good chemical stability, etc.). It is very difficult to process SiC by high-efficiency ultra-precision flatting, which seriously restricts the application and development of SiC semiconductor devices. The Fenton hydroxyl radical (OH) test and sic oxidation test have proved that Fenton reaction can oxidize single crystal sic. During the Fenton reaction, hydroxyl radical, which is an oxidizing oxidant, can be formed. Hydroxyl radical can react with single crystal SiC to form oxide layer. By analyzing the properties of the oxide layer by XPS, it is found that the oxide layer is Sio _ 2. The nano-indentation test of the oxide layer shows that the hardness and modulus of the oxide layer are much smaller than that of the original SiC surface, and the soft oxide layer can be easily removed by abrasive processing. It is proved that the chemical mechanical polishing method based on Fenton reaction can be used for ultra-smooth and flat processing of single crystal SiC. The concentration of hydroxyl radical produced by Fenton reaction and its effect on SiC chemical-mechanical polishing were studied systematically from the point of view of chemical influencing factors. The effect of hydroxyl radical concentration on the oxidation of single crystal SiC was compared. The effect of Fenton reagent composition (catalyst type Fe _ 2 concentration and H _ 2O _ 2) on the formation of hydroxyl radical in Fenton reaction and the effect on SiC chemical and mechanical polishing were studied. It is found that the higher the concentration of hydroxyl radical is, the thicker the oxide layer on sic surface is, the better the chemical and mechanical polishing effect is, and the higher the polishing efficiency is. When the Fenton reagent is composed of 0.02wt.SO4 5wt.H _ 2O _ 2H _ 3, the concentration of hydroxyl radical produced by Fenton reaction is higher, and it can greatly promote the SiC chemical-mechanical polishing, and the super-smooth surface of Ra0.187nm surface roughness is obtained. From the point of view of polishing technology, single factor experiments were carried out on the parameters of abrasive type, abrasive concentration, abrasive particle size, polishing pressure, polishing speed and so on, and the effects on material removal rate and polishing effect were studied. The results show that when the silica sol abrasive is chosen, the abrasive concentration is 20, the abrasive particle size is 50 nm, the polishing pressure is 0.02 MPA, and the polishing speed is 60r/min, the super-smooth surface with surface roughness Ra 鈮，

本文編號(hào)：1894321