Chemical mechanical polishing of poly-crystalline diamond synthesized by mWP-CVD

Chemical mechanical polishing of poly-crystalline diamond synthesized by MWP-CVD ByG.Bharadwaj S.G.K.SKakatiya Institute of Technology and ScienceWarangalTelangana

Under Supervision ofAwadesh Kr MallikBio-Ceramics and Coatings DivisionCSIR-Central Glass and Ceramic Research InstituteKolkata

Diamonds are ForeverOUTLINEINTRODUCTIONNatural Diamond

Basic Facts

Formation

Need for Artificial synthesis

INTRODUCTIONArtificial Diamond : Diamond synthesized in laboratory or by inducing natural conditions

Methods of Synthesis 1). HPHT 2). CVD

CVD : Refers to deposition of thin films on so chosen substrates from its gaseous derivatives under compatible conditions viz. suitable temperature and pressure.

5CVD SCHEMATIC

PRE- FABRICATION Selection of substrate

Selection CVD process

Operation parameters

SAMPLE PREPARATIONSeeding or pre treatment of substrate : Substrate is agitated in a ultrasonic bath in sample of acetone/methanol to get rid of impurities. Later substrate is treated in DND slurry effective nucleation.

Diamond film deposition

SAMPLE FABRICATIONDT1800Process Parameters Substrate Temperature: 750-9000C H2:CH4: 1:99 Pressure : 110-125 Torr Microwave Frequency : 915 MHz EXPERIMENTSample fabricationChemical Mechanical PolishingCharacterization 1. Scanning Electron Microscopy(SEM) 2. Laser Profilometer(CSI) 3. Raman SpectroscopyEXPERIMENT OBJECTIVEChemical mechanical PlanarizationDegree of Differential PolishingComparative study of Quality of DiamondComparative study of Surface Roughness

CMPWhat is CMP ?Planarization: Refers to Planarization is a process that involves smoothening and flattening of surface and thereby removing surface topologiesPrinciple : Mechanical Abrasion and Chemical etchingDescriptionAdvantagesCMP

CHEMO-MECHANICAL POLISHINGCETR-CP4Process Parameters Wafer Pressure : 0.5-2.0 psi Platen velocity : 100-150 rev/min Wafer Velocity (Rotary) : Idle Slurry/Water :1/8 Slurry flow rate : 10 mL/min LASER PROFILOMETERObjective : Provides quantitative maps of surface topology in a 3D view. It gives information about surface roughness of exposed areaPrinciple : Diffuse reflection, Phase changeDescriptionAdvantagesLASER PROFILOMETERBruker IncProcessing parameters Objective lens : 10x Area : 0.866*0.6(0.529mm2)

SCANNING ELECTRON MICROSCOPYSupra 35VP,Carl ZeissObjective : To understand the microstructure of given Conducting SamplePrinciple : Analogous to Cathode ray tubeAdvantagesRAMAN SPECTROMETERMake : Star 500 seriesObjective : To Obtain Quality of sample and appreciate its deviation from ideal casePrinciple : Polarization , Scattering of photonsAdvantages

RESULTSRaman Data

SEM Data

CSI DataRAMAN DATAQuality of Diamond : Id/Ig+IdId: Intensity of Diamond peakIg : Intensity of Graphite peak Stress:Uniaxial =0.347()Bi-axial = 0.528()

*b : Before CMP*a: After CMP

SampleStress(b*)Q(b*)Stress(a*)Q(a*)10.966159.52%62.7%20.895356.65%62.7%Raman Data

CSI DATADrastic decrease in RaDifferential Polishing observedSampleRa(b*)Ra(a*)10.528m0.265m20.535m0.453m34

SEM DATA

CONCLUSIONSCMP is compatible for diamond polishingQuality of diamond is improvedAverage roughness of surface is greatly reducedRaman peak is more definite

ACKNOWLEDGEMENTSSincere thanksToMr. Awadesh Kr MallikDr. Vamsi Krishna BallaAndAll the staff of BCCD divisionEspeciallyMr. Nandadulal DandapatREFERENCESDiamond Films Handbook; Jes Asmussen & J.K. ReinhardDeposition and Characterization of Diamond-like-Nano composite Coatings Grown by Plasma Enhanced Chemical Vapor Deposition Over Different Substrate Materials; Awadesh Kr mallik et alHandbook of Deposition Technologies; Peter K. Martin; 3EdChemical-Assisted Mechanical Polishing of Diamond Film on Wafer; H.Hocheng and C.C.ChenSIMTech Technical Report (PT/01/003/JT);Chemical Mechanical planarization; Dr. Wang Zhengfeng Et alProceedings of 2nd winter education Seminar, Czech Republic; Diamond Chemical vapor Deposition; Alexander KromkaASM handbook, Volume 10-Metals characterization; Jeanne E. Pemberton and Anita L. GuyEvaluation of the measurement performance of a coherence scanning microscope using roughness specimens; Vivek G. Badami et al.Material Science of thin films by Milton Ohring