1 NMOS Fabrication Process Description Modified by Alex Chediak on March 2000 Modified by TAs team Eric Hobbs Paul Hung Paul Friedberg Min She in Fall semester 2002 Part 1 A checklist what do you need in EE143 lab and microlab At the beginning of the semester the TAs team in the current semester should check the following stuff to make sure they are in EE143 lab or microlab 1 General stuff stuff Long Teflon wafer handler Metal tweezer Usage purpose Hold 3 wafer during chemical etching Hold and Transfer wafer Hold wafer quantity 6 comments Need RCA cleaning 6 3 Need RCA cleaning If wafer must be kept clean for example before gate oxidation you should use Teflon tweezer No metal tweezer 2 Use it if you contact HF Usage Field oxidation growth in microlab Gate oxidation growth quantity 1 Intermediate oxide growth and sintering Carry boat 1 Comments Kept in microlab Need RCA cleaning In EE43 lab need RCA cleaning in EE143 lab need RCA cleaning Need HF cleaning in microlab Measure temperature Measure temperature 1 3 Several pairs 1 3 1 Heater for glass bubbler Spin on glass liquid Hold hot stuff Hold the hot end cap Seal the furnace Supply vapor during wet oxidation Heating water into vapor Dope S D Blue wafer transfer Transfer wafer 1 Teflon tweezer HF burn paste 2 Oxidation sintering process module stuff Clean 3 quartz boat Clean 3 quartz boat 3 quartz boat Cylindrical carrier Thermal couple Long glass thermometer Thick cotton gloves Brick End cap Glass bubbler 1 1 Each furnace has one Each furnace have one Connected to center furnace tube 1 1 bottles Kept in the refrigerator Expire in 6 months Need RCA cleaning Week 1 2 box 3 white Teflon cassettes between microlab and EE143 lab Hold wafer in the blue wafer transfer box Oxygen gas Nitrogen gas Forming gas Oxidation Annealing sintering 1 and always put into a plastic bag Kept in the blue box and need RCA cleaning 1 bottle 1 bottle 1 bottle 3 Chemical Cleaning and Etching module stuff Yellow acid resistance gloves usage Put it on when dealing with chemicals quantity 6 pairs Comments Kept in plastic bag after being used Beaker 1 2 1 1 2 1 1 2 1 Each beaker should be labeled and should not mixed Glass heating bath Piranha cleaning Piranha rinsing 5 1BHF 10 1BHF HF rinsing At etching Si etching General rinsing Al etching process Heating oven Tall Teflon Bath White Teflon Cassettes Heat the glass bath RCA cleaning Wafer cleaning and spindrying 3 1 Cassettes handler Handle the cassettes 2 1 Thermometer Measure temperature 1 Keep water temp at 50oC During Al etching Kept in sink6 drawer microlab need RCA cleaning In EE143 lab In sink6 drawer microlab 4 Photoresist Developing and Acetone Stripping Module stuff Beakers Blue wafer transfer box Small bottles and droplets usage Develop photoresist PR rinsing Acetone Acetone rinsing Transfer wafer quantity 1 2 1 2 2 Comments Container for photoresist 3 PR should be obtained from microlab Strip PR Week 1 3 5 Aluminum Evaporations Module Cherry bomb Container cart cup Al targets Tungsten coil Liquid N2 inside 1 For cherry bomb Pour liquid N2 Al source Heating the Al targets 1 1 One bag 50 piece One bag 20 piece 6 Chemical Material in EE143 lab Chemicals Sulfuric acid Hydrogen peroxide 5 1 BHF 10 1 BHF Si etchant Purpose Wafer cleaning Wafer cleaning Etch oxide Etch oxide Etching polysilicon quantity 2 2 Al etchant Ammonium Hydroxide 2 Propanol OCG825 Photoresist Etching Al RCA cleaning purpose 2 2 Cleaning dirty stuff 2 OCG934 developer Acetone Developing PR Strip PR Comments 2 2 2 2 Ask microlab at least 48 hours before you need it Use small bottles to get PR from microlab 2 2 Note 1 The 3 boat and cassettes handler kept in microlab is for microlab usage only Please don t take them back to EE143 lab or take any stuff from EE143 into microlab to prevent contamination 2 RCA cleaning procedure All of the clean stuff needs to be RCA cleaned First put the stuff into one of the white tall Teflon bath then pour 5 part of DI water 1 part of Ammonium Hydroxide then 1 part of H 2O2 RCA liquid should be aspirated after RCA cleaning is done 3 In Fall semester 2002 the small beakers used in the previous years have been replaced with larger beakers At the beginning of the semester the TAs should check the beaker in the following way put a wafer handler with 3 wafer into the beaker fill the beaker with DI water till the water immerse the 3 wafer completely mark the water level Then in future you can always fill the BHF HF poly etchant and so on to this level Part 2 Process Flow Process Overview Week 1 Starting Materials Week 2 Initial Oxidation 5200 Week 3 Active Area Photolithography Week 1 4 Week 4 Gate Oxidation 800 Week 5 Poly Si Deposition In Microlab Week 6 Gate Photolithography Week 7 Source Drain Deposition N Week 7 Source Drain N Drive and Intermediate Oxidation Week 8 Contact Cut Week 9 Metallization Week 10 Metal Definition Week 1 Starting Materials No lab this week Wafers 1 3 p type silicon wafers with a resistivity of 14 16 ohm cm and 100 crystal orientation In addition to work wafers to each student group each section will receive one wafer to be used as a control during week 4 And each session should have one to two TA wafers 2 Blanket Implant 3 0x1012 cm2 B11 60 KeV 3 Uniquely identify each of the wafers Label wafers with diamond scribe Label using small letters near the flat Do not scrib off the edge of the wafer as this will cause the wafer to break DO NOT LABEL YOUR WAFER ACROSS THE CENTER AS IT WILL DESTROY YOUR DEVICES 4 Divide Wafers into lab sections 5 Measure resistivity on one control wafer Resistivity to be reported to students in week 3 Check Masks and Clean the Mask 4 x 4 Chrome Plates 1 ACTV Defines the Active Area Dark Field 2 POLY Defines the Gate Light Field 3 CONT Defines the Contacts Dark Field 4 METL Defines the Metal Light Field 5 Mask Cleaning Procedure At sinks douse chrome side with Acetone If necessary one may lightly use a mask scrubber to remove any residual resist Exercise extreme caution if you choose to use the scrubber so that the mask is not damaged While Acetone is still pooled on mask use IPA 2 Isopropanol to rinse Acetone off Do not use water Blow mask dry using N2 gun Week 1 5 Week 2 Initial Oxidation 5200 Performed by TA in microlab Checklist a 3 white Teflon cassettes and cassettes handler in sink6 drawer in microlab A RCA cleaned 3 quartz boat 6 Standard clean your work wafer in sink6 in microlab please refer to the sink operation manual in microlab
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