(Vacuum) Vacuum)? `Vacua` (1 ) Gas molecular/cm 3

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1 (Vacuum) Vacuum)? `Vacua` (1 ) Gas molecular/cm 3

2 & Medium high vacuum High vacuum Very high vacuum Low vacuum Medium vacuum High vacuum Very high vacuum Ultra-high vacuum Rough vacuum Fine vacuum

3 (Low vacuum) : torr - Rough vacuum,. - Food processing,, (sputtering, LPCVD), (High vacuum) : torr , CRT,, (evaporation), (Ultra high vacuum, UHV) : 10-8 torr - (monolayer) -,,,,

5 E. Torricelli B. Pascal 1783 D. Bernoull 1859 J.K. Maxwell 1874 H.Mcleod 1905 W.Kaufman 1905 W.Gaeda : rotaty Pump, Diffusion pump 1906 M.Pirani M. Knudsen G. Langmuir F.M. Penning Leak detector R.T. Bayard & D. Alpert R. Herb H.J. Schwartz W. Becker Vacuum Pump, Vacuum Gauge,,

6 1 = 76 cmhg H O () Hg : g/cm 3 1 = 76 cmhg x g/cm 3 = 108 cmh O 10 m

8 :. PV = C, P 1 V 1 = P V :. V = kt,, V/V 0 = T/T 0 P 1 V 1 /T 1 = P V /T, PV = kt PV = nrt = NkT 1 P 1 + ρv + ρgh1 = Const.

9 (1/6) : 1g ( = 1.66 x 10-4 g => 1 g = 6.0 x 10 3 ) 3 gas : : gas 1 mv = kt g( v) dv 3 = 4πv m πkt 3 e mv kt dv

10 V (/6) 8kT ( = vg v) dv = 0 πm 1,30 m/s, 467 m/s, 437 m/s, 394 m/sec, 1/ (impinge rate, arrival rate) A (molecules/cm sec) ( Ptorr, TK, Mg/mole) f = 1 4 nv = πmk ) ) 1 x 10-6 torr,, 300 K, N f = ( 1 x 10-6 x 133) / ( x 3.14 x 8 x 1.66 x 10-7 x 1.38 x 10 3 x 300 ) 1/ = 3.8 x /m sec = 3.8 x /cm sec P B T = P MT

11 (3/6) (N 0 ) : 00,, 1 atm,,.4 liter => 6.03 x 10 3 Number density of gases : STP =>.7 x #/cm 3 1 mtorr,, l um 3 => 35 Monolayer : cm 1, (A A g/cm 3 ), (B B g/mole), (N 0 #/mole) => = (( x ) ) / = A N 0 / B (#/cm 3 ) => 1 cm = (A( A N 0 /B) 1/3, = (B/A( N 0 ) 1/3 => monolayer = (A N 0 / B) /3 ex) Ti = 4.51 g/cm 3, = 47.9 g/mole monolayer = 1.476x10 15, monolayer =.6

12 (4/6) Y t = L / v x P x = m v x P t x = m v L x = F X 1 mv = 3 kt force pressure = ( L ) N P = L 0 m v L x = Nm v V mn( vx ) vx dvx nmvx P = = x = Nmv 3V = nn0mv 3V

13 NITROGEN OXYGEN ARGON CARBON DIOXIDE NEON x10 - HELIUM x10-3 KRYPTON x10-4 HYDROGEN x103-4 ZENON x10-5

14 : (torr) 10-4 ~ ~

15 (5/6) (5/6)

16 (6/6) (mean free path : ) : 0 λ = xdn ( cm) n λ 0 ( ) 1 n 3 v =V / λ = 5 / P(1 10 torr) E E t i = 4m m ( m + m ) i i t t cos θ m i << m t m i >> m t Et 4mimt 4m = E i i ( m + m ) mt i Et 4mimt 4m = E t ( m + m ) mi i t i t

17 Collision mean free path Elastic Collision Process/Inelastic Collision Process : Depending on whether the internal energies of colliding particles are conserved # of particle removed by collision in dx Fraction of incident particles colliding in dx Particles Targets dn = σnn dx dγn dx, dx g g dγ Γ Hard ball cross section =Q 1 Uncollided Flux Γ ngσ x x / λ ( x) = Γ e = Γ e 0 Mean Free path Mean time τ = 0 λ = λ υ n g 1 σ dn = n = n σdx g Collision Frequency v = τ 1 = n συ v = Kn g g Rate Constant K =συ

18 : : leakage 3 : 4 : roughing 10 9 <<<< : 6 : roughing 7 : 8 : : main 10 : water 11 : 1 : fore-line

19 Rough pumps (760 torr ~ torr) Rotary oil sealed mechanical pump Sorption pump Venturi pump Booster pump High vacuum pumps ( torr ~ torr) Diffusion pump Cryopump Cryotrap Turbomolecular pump Ultrahigh vacuum pumps ( torr ) Titanium sublimation pump Sputter ion pump

20 Pressure ranges of various Pumps Ultrahigh Vacuum High Vacuum Rough Vacuum Venturi Pump Rotary Piston Pump Dry Mechanical Pump Oil-sealed Mechanical Pump Sorption Pump Blower/Booster Liquid Nitrogen Trap Diffusion Cryopump Turbo Ion pump TSP (Torr)

26 ( )

27 (Oil Diffusion)

28 (Oil Diffusion)

29 (Oil Diffusion)

36 Typical gauge Pressure Ranges (Torr) Gold Cathode Gauge Bourdon Gauge Thermocouple Gauge Pirani Gauge Capacitance Manometer Residual Nitrogen Analyzer Ionization Gauge Residual Gas Analyzer

37 760 torr ~ 1 torr

38 TC

39 Ion Gauge (BA Gauge)

40 Cold Cathode Gauge

1 n dn dt = f v = 4 π m 2kT 3/ 2 v 2 mv exp 2kT 2 f v dfv = 0 v = 0, v = /// fv = max = 0 dv 2kT v p = m 1/ 2 vfvdv 0 2 2kT = = vav = v f dv π m

1 n dn dt = f v = 4 π m 2kT 3/ 2 v 2 mv exp 2kT 2 f v dfv = 0 v = 0, v = /// fv = max = 0 dv 2kT v p = m 1/ 2 vfvdv 0 2 2kT = = vav = v f dv π m n dn dt f v 4 π m kt 3/ v mv exp kt f v dfv 0 v 0, v /// fv max 0 dv kt v p m / vfvdv 0 kt vav. 8v f dv π m k m 0 v / R0 4 T vav.45 0 cm / sec M M p v v fvdv 0 3 fvdv 0 kt m / 3kT v v. 5 m rms v p n dn