Doctoral Thesis

08/20/03

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Particle Trapping Behavior in Plasma-Enhanced Chemical Vapor Deposition Reactor and Its Effects on Wafer Contamination

Abstract...................................................................................................................................................i

Acknowledgements.................................................................................................................................iv

Table of Contents....................................................................................................................................v

1. Introduction.........................................................................................................................................1

        1.1. Background and objectives.......................................................................................................1

        1.2. Characteristics of plasma...........................................................................................................4

        1.3. Literature Survey.......................................................................................................................7

             1.3.1. Rarefied gas flow through a circular tube............................................................................7

             1.3.2. Particle transport in low-pressure parallel plate CVD reactor..............................................8

             1.3.3. Particle trap in plasma reactor............................................................................................9

             1.3.4. Particle behavior in the postplasma period........................................................................13

             1.3.5. Particle formation and growth.......................................................................................... 13

         1.4. Outline of the thesis.................................................................................................................15

References..............................................................................................................................................17

2. Rarefied Gas Flow in a Circular Tube of Finite Length.........................................................................22

        2.1. Introduction.............................................................................................................................22

        2.2. Experimental Apparatus and Procedure....................................................................................23

        2.3. Theoretical Considerations.......................................................................................................25

             2.3.1. Continuum approach........................................................................................................25

             2.3.2. Determination of the conductance by the DSMC method..................................................28

        2.4. Results and Discussion.............................................................................................................30

             2.4.1. Experimental results.........................................................................................................30

             2.4.2. Comparison of the observed conductances with simulation

                       using continuum approach and the derivation of semi-

                       empirical equation............................................................................................................33

            2.4.3. Comparison of the observed results with the simulation

                      by the DSMC method and Hanks-Weissberg’s equation

                      in the transition regime.......................................................................................................39

        2.5. Conclusions.............................................................................................................................41

References.............................................................................................................................................42

3. Fine Particle Transport in a Low-Pressure Parallel Plate

    Chemical Vapor Deposition Reactor....................................................................................................43

       3.1. Introduction...............................................................................................................................43

       3.2. Experimental Technique and Apparatus......................................................................................44

       3.3. Governing Equations and Numerical Simulation..........................................................................46

       3.4. Results and Discussion..............................................................................................................50

              3.4.1. Comparisons of particle visualization and simulation.........................................................50

              3.4.2. Validation of simulations..................................................................................................53

              3.4.3. The simulated flow field...................................................................................................54

              3.4.4. The simulated particle trajectories....................................................................................56

              3.4.5. The particle transport mechanisms...................................................................................57

       3.5. Conclusions..............................................................................................................................60

References..............................................................................................................................................61

4. Fine Particle Trapping in Plasma-Enhanced Chemical Vapor

    Deposition Reactor.............................................................................................................................62

        4.1. Introduction.............................................................................................................................62

        4.2. Experiment...............................................................................................................................63

        4.3. Experimental Results and Discussion.........................................................................................66

             4.3.1. Observation of particle trapping........................................................................................66

             4.3.2. Particle dynamics..............................................................................................................71

             4.3.3. Effect of initial particle number concentration.....................................................................74

             4.3.4. Dependence of trapped particle concentration on plasma

                       Parameter........................................................................................................................75

       4.4. Conclusions..............................................................................................................................78

References..............................................................................................................................................80

5. Characterization of Particle Contamination from Individual

    Process Steps of Plasma Operation.....................................................................................................82

        5.1. Introduction.............................................................................................................................82

        5.2. Experimental Works................................................................................................................83

        5.3. Results and Discussion.............................................................................................................85

               5.3.1. Particle behavior in the postplasma.................................................................................86

               5.3.2. Occurrence time of particle contamination.......................................................................90

               5.3.3. Estimation of residual particle charges in the postplasma..................................................94

        5.4. Conclusions.............................................................................................................................97

References.............................................................................................................................................98

6. Particle formation and trapping behavior in TEOS/O2 plasma

    and their effects on wafer contamination..............................................................................................99

        6.1. Introduction.............................................................................................................................99

        6.2. Experimental Works..............................................................................................................100

        6.3. Results and Discussion...........................................................................................................102

            6.3.1. Particle trapping behavior................................................................................................102

            6.3.2. Particle formation and growth..........................................................................................105

            6.3.3. Effect of particle trapping behavior on wafer contamination...............................................115

        6.4. Conclusions............................................................................................................................116

References............................................................................................................................................118

7. Conclusions......................................................................................................................................120

Nomenclature.......................................................................................................................................123

List of Tables and Figures………………………………………..……………....................................126