CVD_Process_Introduction.ppt

cvd process introduction,outline,1. cvd process introduction 2. cvd type classification 3. dielectric film characteristic 4. cvd film application-darc and lowk 5. q & a,2,outline,1. cvd process introduction 2. cvd type classification 3. dielectric film characteristic 4. cvd film application-darc and lowk 5. q & a,3,1. cvd process introduction,4,cvd(chemical vapor deposition) : the process of depositing solid films using gases or vapors via chemical reaction on the substrate surface.,advantages of cvd : good step coverage can be achieved wide range of materials available good composition control good process control,1. cvd process introduction,5,the sequence of reaction steps in a cvd reaction,diffusion of reaction to surface,diffusion of products from surface,film-forming reaction,subsequent surface reaction,desorption,absorption,1. transport of reacting gaseous species to the substrate surface 2. the reactants are adsorbed on the substrate. 3. the adatoms undergo migration and film-forming chemical reactions. 4. desorption of gaseous reaction by-products 5.transport of reaction by-products away from the substrate surface,cvd process sequence,1. cvd process introduction,(i):mass transport limited at higher temperature deposition rate is sensitive to flux concentration insensitive to temperature (ii):surface reaction rate limited at lower temperature deposition rate is sensitive to temperature insensitive to flux concentration,(i),(ii),1. cvd process introduction,dep rate vs temp,schematic diagrams of transport of reacting gaseous species from source to the substrate surface for (a) surface reaction rate limited reaction, and (b) mass transport limited reaction.,1. cvd process introduction,surface reaction & mass transport limited,components of dcvd systems,1. gas sources 2. gas feed lines 3. mass flow controller 4. reaction chamber 5. heating and temperature control system 6. pumping and pressure control system 7. rf system 8. exhaust,1. cvd process introduction,1. cvd process introduction,10,imd(inter metal dielectric) sin/sicn/sic sio2/fsg/sioch,passivation: sio2 sin sion,beol,feol,sti (shallow trench isolation) poly hm (hard mask) spacer sab (salicide block) smt (stress memory technology) cesl (contact etch stop layer) pmd (pre-metal dielectric),1. cvd process introduction,11,dcvd process precursors: silicon source: teos,sih4, tms oxygen source: o3 ,teos,n2o,o2 phosphorus source: tepo,ph3 boron source: teb,b2h6 fluorine: sif4, nf3 nitric source: n2,nh3 carbon source: c2h2, c3h6,tms: (ch3)4si, 四甲基硅烷, tetramethylsilane teos: si(oc2h5)4, 四乙氧基硅烷, tetraethoxysilane tepo: po(oc2h5)3, 三乙氧基磷烷, triethyl phosphate teb: b(oc2h5)3, 三乙氧基硼烷, triethyl borate,sio2 (usg), sin, sion, psg, bpsg, sicn, sioc, fsg ,outline,1. cvd process introduction 2. cvd type classification 3. dielectric film characteristic 4. cvd film application-darc and lowk 5. q & a,12,2. cvd types classification,13,temperature based hto & lto (high & low temperature oxide) rtcvd (rapid thermal cvd),pressure based lpcvd (low pressure) apcvd (atmospheric pressure) sacvd (sub atmospheric pressure),reagent based silane teos mocvd (metal organic),energy based thermal cvd pecvd (plasma enhanced) hdp (high density plasma),2. cvd types classification,14,pro & con for some typical cvd process,three popular methods are widely adopted to produce sio2. 1. lpcvd teos oxide (typical spacer oxide) si(oc2h5)4 - sio2 + by-products d.r.: 55 a/min. 700c 2. pecvd teos oxide (typical imd oxide) si(oc2h5)4 + o2 - sio2 + by-products d.r.: 7000 a/min. plasma (400c) 3. sacvd o3/teos oxide (typical imd oxide) si(oc2h5)4 + o3 - sio2 + by-products d.r.: 1800 a/min. 400c,2. cvd types classification,heating vs plasma,1. lpcvd si3n4 deposition nh3 + sih2cl2 - si3n4 + by products d.r.: 18 a/min. 740c 780c 2. pecvd si3n4 deposition (2) sih4 + nh3 + n2 - sixnyhz + by products d.r.: 9000 a/min. 400c,2. cvd types classification,pecvd nit,2. cvd types classification,17,plasma,s,heater plate,rf power,process gases,byproduct to the pump,wafer,process chamber,shower head,sacvd: no rf system, no plasma,simple sketch map for pecvd & sacvd process,2. cvd types classification,18,basic principle of hdp cvd,2. cvd types classification,19,over sputtering sputtering of metal and arc layer at the corner too little sputtering cusping of deposition oxide poor gap-filling results in void equilibrium between deposition and sputtering at the corner deposition rate (dc) = sputtering rate (sc) maximized gapfill capability,2. cvd types classification,20,pecvd,hdp cvd,gapfill capability compare,outline,1. cvd process introduction 2. cvd type classification 3. dielectric film characteristic 4. cvd film application-darc and lowk 5. q & a,21,3. dielectric film characteristic,22,1. particle 2. thickness & uniformity 3. refractive index - impurity, composition - density 4. reflectivity 5. stress 6. ftir - composition bonding ratio: si-f, si-h, si-n, si-ch3 - impurity (-h, -oh, h2o) 7, xrf -dopant concentration: b, p,8. etching rate - composition (dopant level) - density 9.sem & tem - step coverage/ gap fill - degree of planarization 10.electrical properties - dielectric constant - dielectric breakdown,3. dielectric film characteristic,23,non-uniformity,range-uniformity,uniformity,3. dielectric film characteristic,24,dep rate, shrinkage,after a thermal cycle, film thickness shrinks. the smaller the shrinkage, the better the film quality.,deposition rate is a very important specification of a cvd process, as it is directly related to throughput.,3. dielectric film characteristic,25,ri can deliver the information for films chemical composition and physical condition.,ri (refractive index),3. dielectric film characteristic,26,stress,3. dielectric film characteristic,27,r is the calculated radius of curvature ts is the substrate thickness tf is the film thickness e is the substrate yongs modulus v is the substrate poisson ratio,g. gerald stoney. proc. r. soc. lond. a80. 172-175 (1909),stress,3. dielectric film characteristic,28,step coverage,teos,silane,out