半導體生產(chǎn)過程培訓課件-wenkub
2023-03-20 04:35:28 本頁面
【正文】 e pattern to be transferred.topatterndevelopedthelightiswithwaferglasschromiumbeaprocesssteponshapeusedaCrystal MaterialCRYSTAL GROWTHw Czochralski Process is a Technique in Making Single173。 Solid173。SemiconductorEEElectronicsState Rectifiersw1907 173。Crystal Siliconw A Solid Seed Crystal is Rotated and Slowly Extracted from a Pool of Molten Siw Requires Careful Control to Give Crystals Desired Purity and DimensionsCYLINDER OF MONOCRYSTALLINEw The Silicon Cylinder is Known as an Ingotw Typical Ingot is About 1 or 2 Meters in Lengthw Can be Sliced into Hundreds of Smaller Circular Pieces Called Wafersw Each Wafer Yields Hundreds or Thousands of Integrated CircuitsWAFER MANUFACTURINGw The Silicon Crystal is Sliced by Using a DiamondTipped Saw into Thin Wafersw Sorted by Thicknessw Damaged Wafers Removed During Lappingw Etch Wafers in Chemical to Remove any Remaining Crystal Damagew Polishing Smoothes Uneven Surface Left by Sawing ProcessTHE CRYSTAL STRUCTURE OF SILICONw A Unit Cell Has 18 Silicons Atomsw Weak Bonding Along Cleavage Planesw Wafer Splits into 4 or 6 Wedge173。techniquetoofainismask,typicallypatternplate.isasensitivecalledphotoresistwhichonthePhotolithographyModelw Figure 1a shows a thin film of some material (eg, silicon dioxide) on a substrate of some other material (eg, a silicon wafer).w Photoresist layer (Figure 1b )w Ultraviolet light is then shone through the mask onto the photoresist (figure 1c). PhotolithographyModel (cont)w The photoresist is then developed which transfers the pattern on the mask to the photoresist layer (figure 1d). w A chemical (or some other method) is then used to remove the oxide where it is exposed through the openings in the resist (figure 1e). w Finally the resist is removed leaving the patterned oxide (figure 1f). PhotolithographyPhotomasks and ReticlesPhotomask This is a square glass plate with a patterned emulsion of metal film on one side. The mask is aligned with the wafer, so that the pattern can be transferred onto the wafer surface. Each mask after the first one must be aligned to the previous pattern. PhotolithographyPhotomasks and ReticlesWhentheseveralbywafer,asiss surface, the photoresist is exposed through the pattern on the mask with a high intensity ultraviolet light. There are three primary exposure methods: contact, proximity, and projection. PhotolithographyPatterningThePhotolithographycalledhassprayedofdissolvesphotoresistmethodsaningases,crustphotoresist.plasmarequireswithtoandremainDespiteisrepeatwetcleantophotoresist Thick (173。100 197。methodoxideheatinginisgrowsOxideuniform.existdefectsproperofhasstatethusidealtransistors.wWet oxide 173。waybutHydrogentheproduce degradeoxidetolayerw OxideastwosomemustthanoxidesbygaseousgaseousoxideslownumbersuseforstillasmultipleasVariables solid state diffusion w Oxidizing species 173。isunwantedaredissolvingwetorwithplasmaproductsprotectstosomemask,ofareetchisetchingtopartpattern achieve high selectivit
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