Lec_12

# Lec_12 - Professor N Cheung U.C Berkeley Lecture 12 EE143...

This preview shows pages 1–8. Sign up to view the full content.

Professor N Cheung, U.C. Berkeley Lecture 12 EE143 F2010 1 Vacuum Basics 1. Units 1 atmosphere = 760 torr = 1.013x10 5 Pa 1 bar = 10 5 Pa = 750 torr 1 torr = 1 mm Hg 1 mtorr = 1 micron Hg 1Pa = 7.5 mtorr = 1 newton/m 2 1 torr = 133.3 Pa 2. Ideal Gas Law: PV = NkT k = 1.38E-23 Joules/molecule –K = 1.37E-22 atm cm 3 /K N = # of molecules T = absolute temperature in K [Note] At T = 300 K ; kT = 3.1E-20 torr-liter 1

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
Professor N Cheung, U.C. Berkeley Lecture 12 EE143 F2010 2 For mixture of non-reactive gases in a common vessel, each gas exerts its pressure independent of others. P total = P 1 + P 2 + … + P N (Total P = Sum of partial pressure) N total = N 1 + N 2 + … + N N P 1 V = N 1 kT P 2 V = N 2 kT ................... P N V = N N kT 3. Dalton’s Law of Partial Pressure
Professor N Cheung, U.C. Berkeley Lecture 12 EE143 F2010 3 4. Average Molecular Velocity v = (8kT/ m) 1/2 where m = molecular weight of gas molecule 5. Mean Free Path of molecular collision = 1 2 d 2 o n where n = molecular density = N/V, d o = molecular diameter [Note] For air at 300 ｰK, = 6.6 P(in Pa) = 0.05 P(in torr) with in mm Assumes Maxwell-Boltzman Velocity Distribution

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
Professor N Cheung, U.C. Berkeley Lecture 12 EE143 F2010 4 6. Impingement Rate, = n v 4 = # of molecules striking unit surface /unit time. = 3.5 10 22 P mT in #/cm 2 -sec with P in torr, m in amu [Note] For air at 300 ｰK ; (in #/cm 2 -sec) =3.8 10 20 P Example Calculation : Contamination from Residual Vacuum For a residual vacuum of 10 -6 torr, = 4 10 14 /cm 2 -sec If each striking molecule sticks to the surface, the equivalent deposition rate of the residual gas is ~ 1/3 of a monolayer of solid per second.
Professor N Cheung, U.C. Berkeley Lecture 12 EE143 F2010 5 Pressure (Torr) Time to form a monolayer (sec) Impingment Rate (Molecules/cm 2 s) Mean free Path (mm) At 25 o C M I P 1 meter! m/min Vacuum Basics (Cont.) Residual Vacuum Plasma Processing CVD

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
Professor N Cheung, U.C. Berkeley Lecture 12 EE143 F2010 6 Thin Film Deposition substrate film Applications: Metalization (e.g. Al, TiN, W, silicide) Poly-Si dielectric layers; surface passivation. Evaporation Sputtering Reactive Sputtering Chemical Vapor Deposition Low Pressure CVD Plasma Enhanced CVD Physical Methods Chemical Methods
Professor N Cheung, U.C. Berkeley Lecture 12 EE143 F2010 7 (1) Evaporation Deposition Al film wafer Al vapor Al hot

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
This is the end of the preview. Sign up to access the rest of the document.

## This note was uploaded on 03/03/2012 for the course EECS 142 taught by Professor Ee142 during the Spring '04 term at Berkeley.

### Page1 / 35

Lec_12 - Professor N Cheung U.C Berkeley Lecture 12 EE143...

This preview shows document pages 1 - 8. Sign up to view the full document.

View Full Document
Ask a homework question - tutors are online