CVD-3 SIO-HU SiO 2 Process Top Electrode, C Bottom Electrode, C Pump to Base Time (s) SiH 4 Flow Standard SIO-HU Process N 2 O Flow N 2 HF (watts) LF (watts) Pressure (mtorr Deposition Time min:s.s Pump to Base Time (s) Wafer Size (in) a 250 300 120 17.5 3200 0 60 0 900 Variable 60 0.5-6 Slide Outline Click to navigate Optical properties Growth Rate and Uniformity Roughness, Stress, Etch Electrical Data Quantox Electrical Data Probe station Elemental Composition Baseline Statistics Optical Model Roughness Data detail XRR Data Quantox SPV-V/Q-V Curve Expanded Probe station data Parameter Extraction method (probe station data) a) Samples smaller than 5mm across will not match the results in this dataset because of edge effects samples other than whole 6 wafers should be placed on aluminum carrier 6/19/14 P. de Rouffignac 1
Optical Properties Wavelength, nm Refractive Index, n a Absorption Coefficient, k b Transmission Optical Model c 630 1.477 0 TBD cauchy a, b) Taken from the optical constants vs wavelength curve; Woollam WVASE 32; 300-800nm 3nm steps; 55,65,75 c) Click on link for detailed description of model 6/19/14 P. de Rouffignac 2
Growth Rate and Uniformity: SIO-HU Run # a Growth Rate b (nm/min) Std. Uniformity c 6 wafer Max/min Uniformity d Linear or non-linear w/time 1 86.3 0.8 % 2.6 % linear 2 86.6 0.8% 2.4 % linear a) Run 1 is the first run after a chamber clean, run 2 is a subsequent run. b) Thickness data from Gaertner Scientific single wavelength (632.8nm) scanning ellipsometer using optical data from page 2 Averaged from 3 wafers from 3 runs c) (1 sigma / mean ) 100 from the 49 point scanning ellipsometer Averaged from 3 wafers from 3 runs d) ((Max Min) / mean) 100 Averaged from 3 wafers from 3 runs 6/19/14 P. de Rouffignac 3
Roughness, Stress, Etch, and Density Stress a, MPa Etch Rate dil. HF b (nm/min) Etch Rate BOE 5:1 c (nm/min) Ra Roughness, nm d Roughness % (Ra/T*100) Density g/cm 3 Density g/cm 3 post-anneal f -215 ± 37 370 ± 12 0.56 0.037% 2.34 e 2.37 a) Measured on FLX-2320-S Thin Film Stress (MET-1) at room temperature using 6 USA ring; seems to be thickness dependent film goes from tensile to compressive; not sure if linear b) Diluted HF solution made by mixing 1 part 49% pure HF with 3 parts DI water (20mL HF + 60mL DI) yielding a HF solution of 15% w/w HF c) 49 % w/w HF d) 345nm film; Measured on SPM-5, Veeco NanoMan AFM, tapping mode, standard tip or Optical profiler e) Measured on a Rigaku Ultima III X-Ray Diffractometer at San Jose State, follow link to report f) Film annealed at 650C for 4 hours- based off of a thickness decrease of 1.1% 6/19/14 P. de Rouffignac 4
Electrical Data Quantox non-contact measurement 126nm SiO 2 ; As-deposited Wafer Type Q eff a (e10 #/cm 2 ) V fb b Q total c (e10 #/cm 2 ) V t d V mid e D it f (e10 #/cm 2 ) Resistivity g (ohmcm) E tunnel h (MV/cm) Dielectric Constant p- type; 11 ohmcm no data 126nm SiO 2 ; Annealed 650 C 4 hours; forming gas Data averaged over 13 sites on 3 separate runs Wafer Type Q eff a (e10 #/cm 2 ) V fb b Q total c (e10 #/cm 2 ) V t d V mid e D it f (e10 #/cm 2 ) Resistivity g (ohmcm) E tunnel h (MV/cm) Dielectric Constant p- type; 11 ohmcm 652-29.4 563-28.4-3.3 402 2.26E+15 6.08 5.06 Click here for example Q-V and SPV-V Curves Data averaged over 13 sites on 1 run a) Q eff = total charge that acts to shift V fb from ideal b) V fb = potential where surface photovoltage is zero c) Q tot = sum of all charges from Si interface through film; charge at V fb from Q-V curve d) V t = Theoretical transistor turn on voltage e) V mid = potential at halfway point between max and min SPV voltage f) D it = density of fixed charges and non-charge based traps at Si-dielectric interface (negative values imply levels are < 1e10 #/cm 2) g) Dielectric Resistivity = Oxide is biased then turned off then voltage is tracked as a function of time h) E tunnel = similar but not same as breakdown; field where any additional charge on dielectric immediately leaks to silicon 6/19/14 P. de Rouffignac 5
Electrical Data MIS Devices on Probe Station Electrical Parameter As-Deposited b Annealed c Leakage Current Density (A/cm 2 at 2MV/cm) a 8.3 10-8 ± 0.2 10-8 2.6 10-10 ± 0.7 10-10 Breakdown Field (MV/cm) 10.14 ± 0.03 10.2 ± 0.1 ε (10 khz) 2.2 ± 0.01 3.97 ± 0.02 ε (100 khz) 1.8 ± 0.01 3.90 ± 0.01 ε (1 MHz) - 3.73 ± 0.06 V FB (@100kHz) d -9 ± 1-3.76 ± 0.08 More data here Q eff (@100kHz) d 9.7 10-8 ± 2 10-8 7.6 10-8 ± 0.2 10-8 N eff (e10) d 60 ± 11 48 ± 1 Q m d 1.0 10-8 ± 0.4 10-8 1.8 10-9 ± 0.1 10-9 N m (e10) d 6 ± 3 1.1 ± 0.1 a) Measured using probe station connected to Agilent 4156c and B1500 analyzers; aluminum pad sizes of 0.0025 cm 2 created using the liftoff technique All values listed derived from averages of at least three measurements per sample b) 1 Wafer batch on 10/04/2013; run 7b 1.5 min deposition time; 6 p-type prime wafers, HF cleaned; 130 nm c) Wafer annealed at 425C in forming gas for 4 hours with contact pads present aluminum pad sizes of 0.0025 cm 2 ; backside contact sputtered gold d) V FB, Q eff, N eff, Q m, N m calculation method on Parameter Extraction Method slide 6/19/14 P. de Rouffignac 6
Film Composition and Contaminants VPD-ICPMS Al a Ca Cr Cu Fe Mg Ni K Na Ti Zn 62.2 151.8 2.7 4.5 67.4 22.7 1.4 34.3 46.7 142.0 2.0 XPS b Si O 33.33 66.67 SiO 2 a) Surface trace metal analysis by VPD-ICPMS; 7mm edge exclusion; values in ppm (by weight) b) Measured on XPS (09/19/2013), after 100s sputter (depth profile) using survey results Carbon less than 1 % 6/19/14 P. de Rouffignac 7
Baseline Statistics TBD a) d b) Blue line = running average c) Red lines = 1 sigma above and below avg 6/19/14 P. de Rouffignac 8
Optical Model Spectroscopic Ellipsometer Model An Bn Cn Ideal or nonideal MSE cauchy 1.4701 0.00226 2.58e-4 ideal < 3 Woollam WVASE 32; 300-800nm 3nm steps; 55,65,75 6/19/14 P. de Rouffignac 9
AFM Data Set Typical SIO-HU Run a) Sample: Run 7b, 1.5min min 130 nm 6 wafer b) Roughness, Ra = 0.56 nm 6/19/14 P. de Rouffignac 10
XRR Data ANALYSIS CONDITION Wavelength (A): CuKa (1.541871) Divergence (deg): 0.03 2-theta offset (deg): 0.0[--] Scale factor: 1.041(7) Background parameter: 1.e-7[--] Material Thickness (nm) Density Roughness (nm) SiO 2 345 2.338 1.86 6/19/14 P. de Rouffignac 11
Quantox Data Example a) Site (-20,40) b) Sample 7A (1.5 min deposition, 130 nm), post 650C anneal 6/19/14 P. de Rouffignac 12
Expanded Probe Station Data 100 khz CV Curves IV Curves a) Sample 7B, 130nm b) X axis of IV curve in MV/cm c) Annealing reduced V FB shift, ΔV FB, and frequency related capacitance drop (frequency dispersion) d) Annealing reduced leakage current density e) Much less frequency dispersion seen in CV curves post anneal 6/19/14 P. de Rouffignac 13
Parameter Extraction Method Er vacuum permivity C FB flat band capacitance d film thickness in meters λ Debye length (cm) A gate area (m 2 ) ε s permivity of Si (F/cm) 11.7*ε 0 C ox Oxide capacitance A gate area (cm 2 ) ε 0 8.854 10 14 F/cm κt thermal energy @ RT (293K*1.3806e- 23 J/K) W MS metal semiconductor work funcon q electron charge (coulombs) V FB Forward flat band voltage N D (Nbulk) Bulk doping concentraon (cm - 3 ) Q eff effecve dielectric charge (coul/cm 2 ) N i Intrinsic carrier concentraon (cm - 3 ) N eff effecve charge concentraon #/cm 2 Dopetype +1 ptype / - 1 ntype' N m mobile charge concentraon Eq. 1 Eq. 2 Eq. 3 W ms = 0.61 kt q ln " N % BULK $ '(dopetype) # & C FB = C oxε s A / λ C ox +ε s A / λ Q eff = C ox(w ms V FB ) A! λ = ε kt $ s # & " q 2 N % Eq. 4 Eq. 5 Eq. 6 N eff = Q eff q Q m = C oxδv FB A The flat band capacitance is calculated in order to extract the flat band voltage, V FB, from the experimental C-V curves. Equations 1 and 2 The forward V FB is then used to determine the effective charge in the dielectric, Q eff. Equations 3 and 4 Equation 5 extracts the density (#/cm 2 ) of effective charges from Q eff and the charge of an electron, q. The effective mobile charge, Q m, in the dielectric is determined using the change in V FB between the forward and backward CV curves using equation 6. The mobile charge density is determined using equation 7. 6/19/14 P. de Rouffignac 14 N i Eq. 7 N m = Q m q