半導(dǎo)體工藝基礎(chǔ)之氧化(-58張)課件

1、章Oxidation氧化1章Oxidation氧化1Oxidation氧化簡介氧化膜的應(yīng)用氧化機(jī)理氧化工藝氧化設(shè)備RTO快速熱氧化2Oxidation氧化簡介2簡介硅與O2直接反應(yīng)可得；SiO2性能穩(wěn)定；氧化工藝在半導(dǎo)體制造中廣泛使用Si + O2 SiO2氧化層簡介3簡介硅與O2直接反應(yīng)可得；Si + O2 SiO2氧化層Oxidation氧化層簡介Silicon4Oxidation氧化層簡介Silicon4氧化膜的應(yīng)用摻雜阻擋層表面鈍化(保護(hù)) Screen oxide, pad oxide, barrier oxide隔離層 Field oxide and LOCOS柵氧化層氧化層應(yīng)用5

2、氧化膜的應(yīng)用摻雜阻擋層氧化層應(yīng)用5摻雜阻擋氧化層Much lower B and P diffusion rates in SiO2 than that in SiSiO2 can be used as diffusion mask氧化層應(yīng)用6摻雜阻擋氧化層Much lower B and P diff表面鈍化(保護(hù))氧化層Pad Oxide襯墊氧化層, Screen Oxide屏蔽氧化層 Sacrificial Oxide犧牲氧化層, Barrier Oxide阻擋氧化層Normally thin oxide layer (150) to protect silicon defects fr

3、om contamination and over-stress.氧化層應(yīng)用7表面鈍化(保護(hù))氧化層Pad Oxide襯墊氧化層, ScrScreen Oxide氧化層應(yīng)用8Screen Oxide氧化層應(yīng)用8Pad and Barrier Oxides in STI Process氧化層應(yīng)用USG: Undoped Silicate Glass未摻雜硅酸鹽玻璃9Pad and Barrier Oxides in STI Application, Pad OxideRelieve strong tensile stress of the nitridePrevent stress induce

4、d silicon defects氧化層應(yīng)用10Application, Pad OxideRelieve 犧牲氧化層 Sacrificial OxideDefects removal from silicon surface氧化層應(yīng)用11犧牲氧化層 Sacrificial OxideDefect器件隔離氧化層臨近器件的絕緣隔離Blanket field oxideLocal oxidation of silicon (LOCOS)Thick oxide, usually 3,000 to 10,000 氧化層應(yīng)用12器件隔離氧化層臨近器件的絕緣隔離氧化層應(yīng)用12Blanket Field O

5、xide Isolation氧化層應(yīng)用13Blanket Field Oxide Isolation氧LOCOS Process氧化層應(yīng)用14LOCOS Process氧化層應(yīng)用14LOCOSCompare with blanket field oxide Better isolation更好的隔離 Lower step height更低臺(tái)階高度 Less steep sidewall側(cè)墻不很陡峭Disadvantage缺點(diǎn) rough surface topography粗糙的表面形貌 Birds beak鳥嘴被淺的管溝(STI)所取代氧化層應(yīng)用15LOCOSCompare with bla

6、nket fiel柵氧化層Gate oxide: thinnest and most critical layerCapacitor dielectric氧化層應(yīng)用16柵氧化層Gate oxide: thinnest and m氧化膜(層)應(yīng)用氧化層應(yīng)用17氧化膜(層)應(yīng)用氧化層應(yīng)用17Silicon Dioxide Grown on ImproperlyCleaned Silicon Surface18Silicon Dioxide Grown on Impro表面未清洗硅片的熱氧化層熱氧化生長的SiO2層是無定形的SiO2分子間趨于交聯(lián)形成晶體未清洗硅片表面的缺陷和微粒會(huì)成為SiO2的成核

7、點(diǎn)這種SiO2層的阻擋作用很差氧化前需要清洗硅片表面19表面未清洗硅片的熱氧化層熱氧化生長的SiO2層是無定形的19氧化前圓片清洗顆粒有機(jī)粘污無機(jī)粘污本征氧化層20氧化前圓片清洗顆粒20RCA清洗Developed by Kern and Puotinen in 1960 at RCAMost commonly used clean processes in IC fabs(1號(hào)液)NH4OH:H2O2:H2O with 1:1:5 to 1:2:8 ratio at 70 to 80 to remove organic .(2號(hào)液)- HCl:H2O2:H2O with 1:1:6 to 1

8、:2:8 ratio at 70 to 80 to remove inorganic contaminates ，DI water rinseHF dip or HF vapor etch to remove native oxide.21RCA清洗Developed by Kern and PuoPre-oxidation Wafer Clean Particulate RemovalHigh purity deionized (DI) water or H2SO4:H2O2 followed by DI H2O rinse.高壓清洗或者放在清洗液中加熱漂洗，最后烘干High pressur

9、e scrub or immersion in heated dunk tank followed by rinse, spin dry and/or dry bake (100 to 125 C).22Pre-oxidation Wafer Clean Part被氧化的硅片上有機(jī)物的清除強(qiáng)氧化劑清除有機(jī)污垢H2SO4:H2O2 or NH3OH:H2O2 followed by DI H2O rinse.High pressure scrub or immersion in heated dunk tank followed by rinse, spin dry and/or dry bak

10、e (100 to 125 C).23被氧化的硅片上有機(jī)物的清除強(qiáng)氧化劑清除有機(jī)污垢23無機(jī)物的清洗先用HCl:H2O液體浸泡再在大的玻璃杯中浸泡清洗 Immersion in dunk tank followed by rinse, spin dry and/or dry bake (100 to 125)24無機(jī)物的清洗先用HCl:H2O液體浸泡24Pre-oxidation Wafer Clean Native Oxide RemovalHF:H2OImmersion in dunk tank or single wafer vapor etcher followed by rinse,

11、 spin dry and/or dry bake (100 to 125)25Pre-oxidation Wafer Clean NatiOxidation MechanismSi+O2SiO2O來源于提供的氧氣Si來源于襯底硅圓片O通過表面已有的氧化層向內(nèi)擴(kuò)散并與Si反應(yīng)生長SiO2氧化薄膜越厚，生長速率越低干氧氧化（Dry Oxidation）26Oxidation MechanismSi+O2SiO2干Oxide Growth Rate RegimeB/A為線性速率常數(shù)；B為拋物線速率常數(shù)27Oxide Growth Rate RegimeB/A為線性 Silicon Dry Oxid

12、ation28 Silicon Dry Oxidation28水汽氧化(Steam Oxidation）Si + 2H2O SiO2 + 2H2At high temperature H2O is dissociated to H and H-OH-O diffuses faster in SiO2 than O2Steam oxidation has higher growth rate than dry oxidation29水汽氧化(Steam Oxidation）Si + 2H2O Silicon Wet Oxidation Rate30 Silicon Wet Oxidation R

13、a濕氧氧化(Wet Oxidation)濕氧氧化法是將干燥純凈的氧氣，在通入氧化爐之前，先經(jīng)過一個(gè)水浴瓶，使氧氣通過加熱的高純?nèi)ルx子水，攜帶一定量的水汽，濕氧氧化法的氧化劑是氧氣和水的混合物。 Si+O2SiO2Si + 2H2O SiO2 + 2H231濕氧氧化(Wet Oxidation)濕氧氧化法是將干燥純凈氧化速率溫度濕氧或干氧厚度壓力圓片晶向(或)硅中雜質(zhì)32氧化速率溫度32氧化速率與溫度氧化速率對(duì)溫度很敏感，指數(shù)規(guī)律溫度升高會(huì)引起更大的氧化速率升高物理機(jī)理：溫度越高，O與Si的化學(xué)反應(yīng)速率越高；溫度越高，O在SiO2中的擴(kuò)散速率越高。33氧化速率與溫度氧化速率對(duì)溫度很敏感，指數(shù)規(guī)律

14、33氧化速率與圓片晶向表面的氧化速率高于表面表面的Si原子密度高34氧化速率與圓片晶向表面的氧化速率高于表面濕氧氧化速率35濕氧氧化速率35氧化速率與雜質(zhì)濃度雜質(zhì)元素和濃度高摻磷的硅有更高的氧化層生長速率，更低密度的氧化層薄膜和更高的刻蝕速率通常，摻雜濃度越高，氧化層生長速率越高；在氧化過程的線性區(qū)(氧化層較薄時(shí))更為顯著。36氧化速率與雜質(zhì)濃度雜質(zhì)元素和濃度36氧化：雜質(zhì)堆積和耗盡效應(yīng)N型雜質(zhì)(P、As、Sb)在Si中的溶解度高于在SiO2中的溶解度，當(dāng)SiO2生長時(shí)，雜質(zhì)向Si中移動(dòng)，這引起雜質(zhì)堆積或滾雪球效應(yīng)B傾向于向SiO2中運(yùn)動(dòng)，這引起雜質(zhì)耗盡效應(yīng)37氧化：雜質(zhì)堆積和耗盡效應(yīng)N型雜質(zhì)

15、(P、As、Sb)在Si中的Depletion and Pile-up Effects38Depletion and Pile-up Effects3氧化速率與HCl摻雜氧化HCl is used to reduce mobile ion contaminationWidely used for gate oxidation processGrowth rate can increase from 1 to 5 percent39氧化速率與HCl摻雜氧化HCl is used to red氧化速率與不均勻氧化氧化層越厚，氧化速率越小對(duì)于更厚的氧化層，O需要更多的時(shí)間擴(kuò)散過氧化層與襯底硅發(fā)生反應(yīng)

16、40氧化速率與不均勻氧化氧化層越厚，氧化速率越小40在干氧中的氧化速率41在干氧中的氧化速率41在合成水汽中的氧化速率42在合成水汽中的氧化速率42二氧化硅色譜43二氧化硅色譜43氧化工藝干氧氧化，薄氧化層 柵氧化層 襯墊氧化層，屏蔽氧化層，犧牲氧化層，等等濕氧氧化，厚氧化層 場氧化層 擴(kuò)散掩膜氧化層44氧化工藝干氧氧化，薄氧化層44Dry Oxidation System45Dry Oxidation System45氧化裝置系統(tǒng)46氧化裝置系統(tǒng)46Dry OxidationDry O2 as the main process gasHCl is used to remove mobile

17、ions for gate oxidationHigh purity N2 as process purge gasLower grade N2 as idle purge gas47Dry OxidationDry O2 as the maiDangling Bonds and Interface Charge48Dangling Bonds and Interface CWet Oxidation ProcessFaster, higher throughputThick oxide, such as LOCOSDry oxide has better quality49Wet Oxida

18、tion ProcessFaster, hWater Vapor SourcesBoilerBubblerFlushPyrogenic50Water Vapor SourcesBoiler50Boiler System51Boiler System51Bubbler System52Bubbler System52Flush System53Flush System53Pyrogenic Steam System54Pyrogenic Steam System54Pyrogenic SystemAdvantage All gas system Precisely control of flow rateDi