Process Guidelines rev. 1 (1063229), страница 4
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It has demonstrated 70 nm 3-sigma overlay. Itis installed on a two mirror beamline that produces a well-tuned beam of X-rays28Basic Photoresist Processing TechniquesSüss XRS 200/2M Stepper Specifications:-Stepper stage: Movement range: ± 90 mm Field size: 26 x 26 mm to 45 x 45 mm Gap: 20-50 µm ± 1 µm (40 typ) Wafer size: 100 to 200 mm Step resolution: 60 nm (wire strain gauge) Alignment accuracy: 100nm (3 sigma + mean) Alignment time: <2 seconds Mask format: IMT/IBM/NIST Mask size: < = 100 mm Alignment mode: Die by die-Scan drive: Movement range: 55 mm Speed: 0.5 to 6.66 mm/sec-Initial conditions for typical operation:-Fields/wafer: 16Wafer size: 5 inchesScan speed: 2 mm/secExposure area: 1in.
x 1in.Typical Stepper Operation:OperationNumber Time(sec)/field Time/wafer (sec)29Basic Photoresist Processing TechniquesMask mount & levelWafer mount & levelStep, level & gapAlignExposeTotal Time per Wafer111616161803055131803080802083985.4 ES-6 Beamline:SAL XRS200/4 (Mod 4 Stepper)Contact : Quinn Leonard (quinn@nanotech.wisc.edu)The SAL XRS 200 Model 4 is installed on a scanning mirror beamline and is in the processof being developed in collaboration with SAL.
The Model 4 and the 2M support the NISTand IBM X-ray mask formats and can handle wafers from 3 to 8 inches in size.30Basic Photoresist Processing TechniquesSAL XRS/Mod 4 Stepper Specifications:-Stepper stage: Movement range: ± 125 mm Field size: 26 x 26 mm to 50 x 50 mm Gap: 10-50 µm ± 1 µm (40 typ) Wafer size: 75 to 200 mm Step resolution: 20 nm (wire strain gauge) Alignment accuracy: 70nm (3 sigma + mean) Alignment time: < 1 seconds Mask format: IBM/IMT/NIST Maximum field size: 50mm x 50mm Alignment modes: Global, die by die-Scan drive: Movement range: 60 mm Speed: 0.1 to 20 mm/sec-Initial Conditions for Typical Operation: Fields/wafer: 16 Wafer size (in.): 6-Typical Operation:OperationNumber Time(sec)/field Time/wafer (sec)Mask mount & level1180180Wafer mount, gap & level16060Align16580Exposure1613208Step & level1658031Basic Photoresist Processing TechniquesTotal Time per Wafer4285.5 EUV Beamline:Wide Band and Narrow Band EUV BeamsContact: Victoria Golovkina (golovkina@nanotech.wisc.edu)32Basic Photoresist Processing Techniques-U2 undulator: The new U2 undulator is high energy permanent magnet devicecovering photon energies up to 400 eV at higher orders.
Usefulharmonics: 1st, 3rd, 5th, 7th, 9th. The 3rd harmonic is used for EUV(92.5 eV or 13.4 nm). Parameters:o Type: Pure, Permanent Magneto Full-Strength Poles: 101oPole-width: 94 mmoPitch: 68.2mmo Max Field: 7.17+ kGo Min. Magnetic Gap: 24 mm33Basic Photoresist Processing Techniques-Wide band: high flux direct undulator beam:WaferSiN windowMultilayer mirror#2Multilayer mirror #3Multilayer mirror #1Undulator34Basic Photoresist Processing Techniques-Narrow band: through OMM monochromator:WaferSiN windowMultilayer mirrorExit slitM1 mirrorSpherical gratingEntrance slitM0 mirrorUndulator35Basic Photoresist Processing TechniquesPart 6: Post Exposure Bake (PEB) and DevelopmentGeneral Comments:7. Not all resists require a Post Exposure Bake (PEB), i.e.
PMMA. Make sure youunderstand your resist’s processing parameters before you begin. Check withQuinn Leonard if you are unsure.8. The PEB process is similar to the Post Applied Bake (PAB). See Section 4.2Baking a Wafer.9. If the PEB temperature is different than the PAB temperature, remember to allowtime for the hotplate to equilibrate before use.10. Varying PAB/PEB temperatures and time will affect clearing dose, contrast, andfilm thickness. Make sure you understand these affects when choosing astarting point. See Appendix ? for more information.6.1 Post Exposure Bake:-The time between exposure and PEB is extremely important when using CARs.Make sure you understand the chemistry that occurs and how to schedule yourtime appropriately.
Environmental contamination will cause a change insensitivity or a “t-topping” effect.1. Select the hotplate vacuum surface diameter for your wafer size (See Part 3 forspecific hotplate operations).2. Using a pair of wafer tweezers with your right hand, position your wafer abovethe hotplate chuck, centering between the appropriate pin holes for your wafersize.
See Fig. 1.36Basic Photoresist Processing TechniquesCenter waferbetween thesepin holesFigure 1: Center your wafer between the pin holes. Each pin hole pair corresponds to a wafer size.3. This next step requires good coordination. While holding the wafer above thehotplate with your right hand, use your left hand to hold a timer (set to your baketime) and depress the vacuum toggle switch. Press start on the timer at thesame time you depress the vacuum and lower the wafer onto the hotplate chuck.Bake time variation has a critical effect on photoresist performance; following thesame procedures every time will produce the most reproducible results.
See Fig.2.Figure 14: How to position your hands.37Basic Photoresist Processing Techniques4. As time nears completion, position yourself in the same manner above. You willdisengage the vacuum switch at the same time engaging the nitrogen switch astime expires. This will produce a nitrogen “pillow” where the wafer will floatabove the chuck. Quickly capture the wafer with your tweezers. The wafer willoften float across the entire chuck surface, so be prepared.5. Immediately place your wafer on the stainless steel hood surface and allow yourwafer to cool. Doing this set reproducibly will help ensure the tight processcontrols required by Chemically Amplified Resists (CARs).6. Once the wafer is cool, proceed to developing the wafer.6.2 Developing your Wafer:1. Pour the appropriate developer for your resist into a crystallization dish (size ofdish will vary depending on the size of your wafer).
Lay a large TexWipeunderneath your dish to absorb any spills or splashes. Remember to label theTexWipe with the chemical used, your name, and the date.2. Appropriate labeling benefits all users. It allows staff to properly dispose ofchemicals if left out. It also notifies other users of possible contamination fortheir resists or processes.3. If you will be developing several wafers over an extended period of time, pleaseuse a crystallization dish cover or watch glass.
Developer life is dependent onthe amount of carbon dioxide absorbed from the air and by the amount ofphotoresist dissolved.4. Set timer to your development time.5. Using wafer tweezers, lower your wafer into the developer while hitting start onthe timer.6. Mild agitation of the wafers or circulation of the developer along the wafer planeis recommended for uniform developing.7. Rinse or quench your wafer in DI wafer or the appropriate solvent immediatelyafter the development time expires.8.
Dry your wafer with a low pressure nitrogen gun. You can blow your features offyour wafer if you are not careful! Hint: Place a TexWipe on the counter surface.Hold your wafer (with tweezers) vertically on the TexWipe and blow the liquid offfrom top to bottom. The TexWipe will absorb any liquid blown off the wafer.Repeat to backside of wafer.38Basic Photoresist Processing Techniques9. Dispose the developer in the appropriate waster container. If you are uncertainabout which container to use, consult the waste chart located in the processcleanroom or contact Quinn Leonard.10.
Rinse the glassware with DI water and dry with TexWipes before returning theglassware to the storage shelves.6.3 Cleanup:-Ensure that your work area is clean. Throw out any TexWipes that you used andmake sure that your work area is clean for the next user.-Replace the aluminum foil in the spinner.
Throw out any pipettes or wipes used.Store your resist bottles in the fume hood. Make sure you turn off the motorpurge and the spinner.-Wash and dry any glassware you used. Return them to the storage shelves.-Return any tweezers, pens, and timers used to their storage areas.-Label and store your samples appropriately.39Basic Photoresist Processing TechniquesPart 7: Laboratory Usage and SafetyGeneral Comments:Before gaining access to the CNTech clean rooms, you must obtain a radiation badge fromthe operator on duty at the SRC. You should also contact Bruce Neumann, the SRC safetyofficer, for a safety training session pertaining to the SRC.7.1 Clean Room Functions:7.1.1 Contamination Control:The primary limitation to clean room cleanliness is the people using the clean room.By industry standards, CNTech has very lax clean room procedures.
However, strictadherence to our rules and common sense allow us to maintain a level ofcleanliness adequate for the types of work done at CNTech.You are the biggest source of contamination in the clean room. Your clothes, yourfeet, your skin, and your hair produce particulates which may compromise yourresearch goals.A few obvious rules:• Do not bring anything into the clean room which is not absolutely necessary forthe work you are doing.•Do not wear make-up.•Do not comb your hair in the clean room or gowning room.•Bare legs must be covered.•Socks or nylons must be worn along with regular shoes. Sandals, cleatedsole shoes or boots are not allowed.•Do not use pencils or eraser in the clean room.•Do not wear dirty clothes, particularly muddy boots or shoes into the clean room.•Unpack cardboard boxes outside the clean room.
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