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1、河南科技大學(xué)畢業(yè)設(shè)計(jì)(論文)噴涂工藝對(duì)氮化硅涂層品質(zhì)的影響摘要鑄造多晶硅生產(chǎn)流程中的第一道工序就是坩堝涂層的噴涂。工業(yè)中通常使用的坩堝是石英或石墨坩堝,熔融硅與坩堝接觸時(shí)不可避免的產(chǎn)生反應(yīng)粘連,同時(shí)坩堝中的雜質(zhì)也會(huì)進(jìn)入硅熔體中。高濃度的雜質(zhì),如C、O、Fe、Ca等將使少子壽命顯著降低,影響電池性能。通常在坩堝上涂敷涂層使熔體與坩堝壁隔離,來減少反應(yīng)粘連使晶錠順利脫模,并阻止坩堝中的雜質(zhì)在長(zhǎng)晶過程中進(jìn)入熔硅中。高純的Si3N4自擴(kuò)散系數(shù)低,且耐高溫性能和化學(xué)穩(wěn)定性良好,抗雜質(zhì)擴(kuò)散能力強(qiáng),與熔硅不發(fā)生反應(yīng),通常被用來作為多晶硅鑄造的涂層材料.坩堝涂層的制備方法很多,現(xiàn)在通
2、常采用成本低廉的氮化硅涂層制備技術(shù),它是在石英坩堝內(nèi)壁上直接噴涂氮化硅涂層的,并將涂有氮化硅涂層的石英坩堝在1050℃下進(jìn)行燒結(jié),形成結(jié)構(gòu)更加致密的氮化硅層。但是由于這種技術(shù)缺乏檢驗(yàn)技術(shù)支持,工藝可追溯性差,實(shí)際生產(chǎn)中晶錠常會(huì)出現(xiàn)粘堝現(xiàn)象,進(jìn)而在晶錠內(nèi)引起雜質(zhì),裂紋,影響硅片的質(zhì)量。所以我們希望通過改變氮化硅與純凈水的配比,坩堝的預(yù)熱溫度及溶液攪拌混合方式進(jìn)行產(chǎn)品優(yōu)化。研究結(jié)果表明:氮化硅與水的配比為1:4時(shí)效果最好,氮化硅涂層無裂紋,顆粒結(jié)合緊密。坩堝預(yù)熱溫度為50℃時(shí)最佳,氣孔少。超聲波與機(jī)械共同攪拌比單純的機(jī)械攪拌的效果要好,涂層的顆粒分布更均勻,表面無孔洞。坩
3、堝在1050℃燒結(jié)時(shí),氮化硅涂層與坩堝之間相互擴(kuò)散。關(guān)鍵詞:多晶硅,氮化硅涂層,SEM,宏觀組織23河南科技大學(xué)畢業(yè)設(shè)計(jì)(論文)QualityOfSi3N4CoatingInfluencedBySprayingTechnologyABSTRACTIntheprocessofmc-SipurificationbyPhysicalMetallurgicalMethod,sprayingSi3N4coatingisthefirstworkingprocedure,crucibles,typicallygraphiteorquartzcrucibleshavebeenused
4、assupportofmeltingsilicon.However,inthecastingprocess,therearereactionadhesionsontheinterfaceofmeltingsiliconandcrucible.Moreover,highdensityofimpurity,suchasC,O,Fe,Ca,whichplaysacrucialroleonthedegradationofmc-Sisolarcellsperformance,areusuallyincorporatedthroughthecontactofthemeltwith
5、thecruciblewalls.UsuallycoatinghasbeenspayedonthecruciblewallasreleaseagenttoavoidmeltingSiliconcontactingwiththecruciblewalldirectly,eventuallydecreasetheimpuritydiffusionfromcrucible.HighpuritySi3N4hasbeenusedastypicalcoatingmaterialsinthemc-Sicastingprocessforitslowself-diffusioncoef
6、ficient,goodhightemperatureresistanceandchemicalstability.Therearekindsofmethodstofabricatecoating;nowweadoptlowcostmethodforSi3N4coating.Inthisstudy,weadoptthetechniquethatsprayingSi3N4onthewallofcrucibledirectly.WesinterthecruciblewithSi3N4coatingatthetemperatureof1050℃.Butthistechniq
7、uelackstesttechnology;thetraceabilityofcraftworkisverybad.ThereareadhesionsontheinterfaceofmeltingSiliconandcrucible.Moreover,itcanbringinimpurityandcrackle;affecttheproducts’quality.SowehopetochangetheproportionofpurewaterandSi3N4,warm-uptemperatureandthewayofmixingliquortoopt