發(fā)布時間：2018-03-27 18:06

  本文選題：金剛石砂輪　切入點：IC硅片　出處：《上海大學(xué)》2016年博士論文

【摘要】：IC芯片是電子計算機、智能手機和平板電腦等智能終端設(shè)備所用微處理器的核心部件。目前,全球90%以上的IC芯片均采用硅片作為襯底材料,可以說IC芯片硅片襯底材料減薄磨削的技術(shù)水平,直接關(guān)系到未來一個國家微處理器的發(fā)展水平。目前制造IC芯片的主流技術(shù)為采用精密金剛石砂輪的自旋轉(zhuǎn)磨削工藝,該技術(shù)對砂輪的自銳性要求極高,磨削后的硅片表面須達到納米級表面粗糙度(Ra)和微米級亞表面損傷層厚度(SSD)。當前國產(chǎn)砂輪普遍自銳性低,磨削出的襯底硅片存在硅片表面Ra和SSD過大的問題,容易導(dǎo)致硅片碎裂而造成巨大經(jīng)濟損失。特別是制備高端IC芯片時需使用直徑大于Ф200 mm的硅片襯底材料,而發(fā)達國家將磨削大直徑硅片的精密金剛石砂輪作為戰(zhàn)略物質(zhì)限制對中國出口,對其材料組分、配方及制作工藝嚴格保密,因此急需針對該金剛石砂輪的材料及其制備工藝開展系統(tǒng)研究。針對磨削大尺寸硅片襯底用精密金剛石砂輪自銳性低、磨削出的襯底硅片存在表面Ra和SSD過大的問題,通過研究樹脂砂輪和陶瓷砂輪的造孔機理,采用在砂輪中引入大量氣孔,弱化粘結(jié)劑與磨料結(jié)合力的方法,開發(fā)制備大氣孔率砂輪試樣的混料、成型、燒結(jié)和修整的新工藝,制備出新型陶瓷粘結(jié)劑和樹脂粘結(jié)劑。采用TG-DSC、FTIR、SEM和EDS等方法,觀察試樣形貌并對比分析試樣力學(xué)強度等數(shù)據(jù),探索砂輪材料含量對試樣力學(xué)強度的影響規(guī)律,開展砂輪材料性能優(yōu)選工作。研究材料組分及含量對砂輪磨削性能的影響,開展硅片磨削機理研究并進行砂輪試樣的工業(yè)化應(yīng)用試驗。硅片加工分為粗磨和精磨兩道工序,分別采用鋒利耐用的陶瓷金剛石砂輪和拋光性能好的樹脂金剛石砂輪。陶瓷砂輪使用研制的Na2O-Al2O3-Si O2-B2O3多元陶瓷粘結(jié)劑,其燒結(jié)溫度685℃,該溫度下其流動性為140~150%,膨脹系數(shù)為4.46×10-6m/K,接近金剛石的膨脹系數(shù)4.40×10-6 m/K。樹脂砂輪使用研制的BMI樹脂粉,粒徑為10~40μm,密度1.33 g/cm3,吸水性在0.2%~0.3%,TG曲線顯示該樹脂的5%熱失重溫度為348.9℃。開發(fā)包括聚合物粉在陶瓷砂輪粘結(jié)劑橋造孔和陶瓷粘結(jié)劑濕法球磨等工藝,在陶瓷砂輪料中加入6%體積百分數(shù)的聚合物粉末,在最高溫度685℃燒結(jié)后在陶瓷粘結(jié)橋上生成較多5~8μm的氣孔。通過添加聚合物成孔弱化陶瓷粘結(jié)劑與磨料的把持力,使磨鈍的金剛石磨粒自行脫落,提高砂輪自銳性。添加聚合物粉的陶瓷粘結(jié)劑砂輪的毛坯采用熱壓工藝成型,熱壓溫度為215℃,壓力10 MPa。設(shè)計陶瓷粘結(jié)劑配方并經(jīng)多次�；扑�,采用自制行星式球磨機和開發(fā)的濕法球磨工藝將陶瓷粘結(jié)劑研磨成粒徑小于2μm的粉末。采用最大粒徑為90μm到2μm的8種金剛石制作陶瓷和樹脂砂輪,開展磨削硅片試驗。試驗結(jié)果表明:8種金剛石制作陶瓷和樹脂砂輪磨削出的硅片表面粗糙度Ra可從378 nm至1.91 nm,硅片SSD可從16.5μm至0.92μm,砂輪MMR可從35μm/s至0.3μm/s。多晶金剛石的磨削效果較單晶金剛石的更好,在磨削工件Ra、磨削電流、MMR和SSD等方面均有優(yōu)勢。同粒徑條件下,陶瓷砂輪較樹脂砂輪的MMR高20%,SSD高20%,磨削電流低5%,但Ra高近100%。造孔劑的成孔機理分為占位后去除成孔和氣體發(fā)泡成孔等。結(jié)果表明:發(fā)氣型造孔劑制作的砂輪試樣磨削效果較好。添加造孔劑后,金剛石砂輪磨削時不需強制修銳,砂輪的自銳性明顯改善。硅片SSD由3.5μm減至0.92μm,硅片表面Ra從6.72 nm減至1.91 nm。當加工磨削余量為20μm的Ф200 mm硅片時,砂輪壽命為25000片。多晶金剛石磨料的粗糙表面可增加其與粘結(jié)劑的嵌合力,減少磨料脫落造成的磨削劃傷。多氣孔結(jié)構(gòu)可減小砂輪與硅片工件的接觸面積并降低二者之間摩擦力,固體潤滑劑可減小樹脂粘結(jié)劑與硅片的摩擦系數(shù)并降低磨削功率。采用硅屑EDS和SEM等測試方法,通過對比硅屑與硅片表面磨痕寬度及即將脫落的顆粒直徑,確定2μm的顆粒為硅屑顆粒。通過分析磨削液中存在的顆粒狀磨屑和拉絲狀磨屑,提出在磨削過程中硅片材料存在脆性崩裂和塑性變形兩種去除機制的機理。經(jīng)工業(yè)化應(yīng)用驗證表明,采用在砂輪中引入大量氣孔,弱化粘結(jié)劑與磨料結(jié)合力的方法,制備出的砂輪持續(xù)鋒利磨削,可控制磨削時砂輪對硅片的擠壓力,多氣孔砂輪的自銳性提高,硅片表面達到納米級硅片表面粗糙度和微米級硅片亞表面損傷層要求,砂輪試樣磨削硅片無碎裂現(xiàn)象,滿足IC芯片襯底硅片的磨削要求。
[Abstract]:IC chip is the core component of the electronic computer, microprocessor for intelligent mobile phone and tablet computer and other intelligent terminal equipment. At present, more than 90% of global IC chip using silicon as the substrate material, can be said that the technical level of thinning grinding IC chip silicon substrate materials, directly related to the future development of a national mainstream microprocessor. The current IC chip manufacturing technology for the self rotating grinding process using diamond grinding wheel, the grinding technology on self sharpening of the requirements that a silicon wafer surface after grinding to achieve nanometer surface roughness (Ra) and micron surface damage layer thickness (SSD). The current domestic general self sharpening grinding wheel is low. The silicon substrate is grinding out the existence of Ra and SSD on silicon wafer surface is too large, easily lead to wafer fragmentation caused enormous economic losses. Especially the preparation of high-end IC chip for use with diameter greater than 200 Silicon substrate materials of mm, while the developed countries will be diamond grinding wheel with large diameter silicon wafer grinding as a strategic material restrictions on the export of China, its material composition, formulation and production process strictly confidential, so there is an urgent need for the material of diamond grinding wheel and its preparation technology development system research. For the large size silicon substrate by precision grinding self sharpening diamond grinding wheel, grinding out the surface of the silicon substrate is Ra and SSD. The pore forming mechanism of resin grinding wheel and ceramic grinding wheel, with the introduction of a large number of pores in the grinding wheel, the weakening of the bonding agent and method of abrasive binding force, the development of material preparation, mixing air hole ratio of wheel specimen the forming, sintering and dressing, preparation of new ceramic binder and resin binder. By using TG-DSC, FTIR, SEM and EDS, to observe the surface morphology and the comparative analysis of mechanical strength Data, explore the influence of wheel material content on mechanical strength and work performance of wheel material optimization. The influences of composition and content of materials on the grinding performance of grinding wheel, industrial application test sample and study the grinding mechanism of silicon wafer processing and grinding. The two process for coarse grinding, using resin ceramic diamond grinding wheel and diamond grinding wheel polishing performance sharp and durable good. Na2O-Al2O3-Si O2-B2O3 multiple ceramic binder ceramic grinding wheel used developed, the sintering temperature is 685 degrees centigrade, the temperature of the flow is 140~150%, expansion coefficient is 4.46 * 10-6m/K, BMI resin powder expansion coefficient is close to 4.40 * 10-6 m/K. diamond resin grinding wheel used for the particle size of 10~40, m, density of 1.33 g/cm3, water absorption in 0.2%~0.3%, TG curve shows 5% heat loss temperature of the resin is 348.9 DEG. Development including polymerization Powder pore in ceramic grinding wheel binder bridge and ceramic binder by wet milling process, the polymer powder with 6% volume fraction in ceramic grinding wheel material, the maximum temperature of 685 DEG C after sintering in ceramic bonding bridge 5~8 m generated more pores. By adding polymer into hole weak ceramic binder and abrasive holding force so, blunt diamond abrasive wheel off on their own, improve self sharpening. The polymer powder ceramic binder wheel blank by hot pressing molding, hot pressing temperature is 215 DEG C, the pressure of 10 MPa. design of ceramic binder and has broken glass, by wet milling process of self-made planetary mill and the development of the ceramic binder a particle size less than 2 mu m powder. The maximum particle diameter of 90 mu m to 8 mu m 2 Diamond making ceramic and resin grinding wheel, grinding out wafer test. The test results show :8縐嶉噾鍒氱煶鍒朵綔闄剁摲鍜屾爲鑴傜爞杞（鍓婂嚭鐨勭鐗囪〃闈㈢矖緋欏害Ra鍙粠378 nm鑷，

本文編號：1672637