Optical Emission Analysis Of CF4/CHF3/Ar Plasma Etch Of Oxide
Optical Emission Analysis ofCF4/CHF3/Ar Plasma Etch of OxideAnjali WaliaIrvington High School8/13/151
RIE : Reactive Ion Etch Type of dry etching Chemically reactive plasmaremoves material depositedonon wafers Plasma created by applying strong RF field Electrons accumulate on platen - - DC selfBias Plasma sheath has positive charge Positive ions drift toward wafer platen andreact with surface2
Centura MxP Magnetically enhanced RIE chamber Cathode receives RF power Rotating magnetic field applied - moreionized, reactive gas Magnetic field decreases DC bias by loweringresistance of plasma Channels distribute He across back of wafer - prevents photoresist reticulation3
CF4/CHF3/Ar etchingFFCFFCFFFHOOPRPRSiO2Si substrate F reacts with SiO2 - O2 becomes a part of the etch C forms teflon-like polymer that is attacked by O2 Polymerizes over non-O2 bearing surfaces4
Optical Emission Spectroscopy Method of chemicalanalysis Intensity of light emittedfrom spark at particularwavelength used to determinerelative quantities of elements in plasma Wavelength - identity of element Intensity proportional to number of atoms ofelement Used to obtain spectrum of etch process5
Optical Setup Ocean Optics spectrometer with range Centura MXP195 – 900 nm Ocean Optics software forFiberspectrum 2 meter Fiber Patch CableSpectrophotometerfrom Thorlabs with range200LaptopUSB1200 nm6
Test Structure 2 main sets of tests: Oxide Etch and Spacer Etch Different wafers run for each set: 10 μ SiO2/Si1 μ SiO2/SiPR/SiThin PR(DUV 210 - 0.6)/10 μ SiO2/SiPR(OiR 906 - 12)/1 μ SiO2/Si Ran O2 Clean process on a Bare Si wafer before andafter each test to clean the chamber Each process run for 10 minutes Scans every 10 milliseconds7
Standard Etch Profiles8
Relevant Wavelength DataSpeciesO2 (O)N2ArFCO2COCF4 (CF)SiF4 (SiF)CH4 (CH)C4F8 (CF2)CNNOWavelength437, 497, 502, 533, 544, 615, 616, 646, 700, 725, 777337, 326, 331, 390, 391, 428, 576, 580, 655, 662, 671, 688,727, 790451, 485, 550, 603, 697, 707, 750, 416624, 635, 641, 677, 683, 686, 687, 690, 691, 697, 714, 713,720, 733, 740, 743, 751, 755, 757, 761 776, 780288, 290, 337484240, 256640, 777431249, 252, 246, 255, 260, 263, 271, 275, 288, 292, 321359, 386, 387, 418, 420, 422, 647, 693, 709, 785237, 245, 256, 268, 272, 2869
Ar peak 350 nm - overwhelmed byCF / polymerization reactions10
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Relevant Wavelength DataSpeciesO2 (O)CO2COCF4 (CF)SiF4 (SiF)Wavelength437, 497, 502, 533, 544, 615, 616,646, 700, 725, 777288, 290, 337484240, 256640, 77712
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Suggested Further Tests Rerun spacer etch on PR patterned oxide, testfor polymerization after 4 minutes Testing of nitride films to see if they crosscontaminate between etches, specifically lowstress nitride and stoichiometric silicon nitride17
Thanks for listening!Special Thanks To Ryan Rivers Jayss Marshall Jesse Cheryl Marilyn Bill Flounders18
Works Cited Centura MxP manual P5000 Endpoint Manual19
Optical Model Created model to correct for loss of intensitythrough fiber Used dataset for optical fiber from Thorlabs toapproximate attenuation coefficients forspectrometer output Back calculated to find input intensity using theknown output intensity and percenttransmittance No effect on dataset20
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CF4/CHF3/Ar etching C F F F F F F H F Si substrate PR PR SiO2 O O C F reacts with SiO 2 - O 2 becomes a part of the etch C forms teflon-like polymer that is attacked by O 2 Polymerizes over non-O2 bearing surfaces 4. Optical Emission Spectroscopy Method of chemical analysis
ISOTROPIC PLASMA ETCHING 1. Start with inert molecular gas CF4 2. Make discharge to create reactive species CF4 CF3 F 3. Species reacts with material, yielding volatile product Si 4F SiF4 4. Pump away product 5. CF4 does not react with Si; SiF4 is volatile ANISOTROPIC PLASMA ETC
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Ecotoxicological characterization factor [PDF·m3·day/kg]: Emission to urban air Emission to cont. rural air Emission to cont. freshwater Average 1,8E 02 1,8E 02 4,5E 02 Worth Case 4,6E 02 4,6E 02 1,2E 03 Emission to urban air Emission to cont. rural air Emission to cont. freshwater cancer non-canc. total cancer non-canc. total cancer non-canc .
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A novel all-optical sampling method based on nonlinear polarization rotation in a semiconductor optical amplifier is proposed. An analog optical signal and an optical clock pulses train are injected into semiconductor optical amplifier simultaneously, and the power of the analog light modulates the intensity of the output optical pulse through
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