臺灣博碩士論文加值系統

本論文研究分為兩個部分，第一部份主要研究垂直8吋單晶片快速升溫反應爐爐內混合對流流場結構，而第二部分我們也提供一個可在晶圓背面通入冷卻氣體之支撐座，以改善在快速升溫爐降溫過程中晶圓之均溫性並且提高晶片降溫速率。
第一部份研究中，我們採用兩種不同結構之多孔板，一個為2410孔直徑2mm之等孔多孔板，另一個為中央直徑1mm外圍直徑3mm的不等孔多孔板；而研究的焦點放在晶圓表面溫度、爐體內壓力、進氣流量對於爐體渦流流場結構的影響；本實驗中我們發現，在低浮慣比(buoyancy-to-inertia ratio)時，爐內流場結構主要為衝擊塞柱流(plug flow)，流體直接衝擊到晶圓表面而且整個結構並沒有渦流之產生。對於非等孔板而言，在低浮慣比時流體易從較大直徑的孔流出，因此在爐體中央會形成一個很大的對稱渦流(mixed flow 1)。而當我們提高晶圓溫度時，在爐體兩側會有渦流產生(mixed flow 2 或mixed flow)，並且隨著晶圓溫度漸漸增高(浮慣比增高)，此渦流會漸漸變大，最後佔據整個爐體，流場結構完全由浮力驅動流(buoyancy-induced flow)所支配。
在第二部分的研究中，我們設計一個可在背面通入冷卻流體的晶圓支撐座，藉由增加入口流量與背面冷卻空氣之流量以增快晶圓之降溫速率；研究中也發現，適當的入口及背面冷卻空氣流量可明顯的提高晶圓的均溫性；但太高的流量卻會破壞其均溫性。因此適當的流量不但可以提高晶片的均溫性，也可以直接提高晶圓的降溫速率，以減低製程所需要的時間。

A two-part experimental study is conducted here to unravel the vortex flow patterns and to improve the wafer temperature uniformity in a single wafer vertical rapid thermal processor (RTP) for IC processing. Flow visualization is carried out in the first part to investigate the vortex flow characteristics in an experimental lamp heated, vertical 8-inch single wafer rapid thermal processor. While in the second part of the study the possible improvement of the wafer temperature uniformity during the ramp-down period by placing an air cooled copper plate right below the silicon wafer is explored.
In the flow visualization experiment two different showerheads are tested. One is the uniformly perforated showerhead with 2410 holes of 2 mm in diameter and the other is the nonuniformly perforated showerhead with the hole diameter varying from 1 to 3 mm. A thick copper plate is used to replace the actual silicon wafer, intending to have a nearly isothermal boundary condition on the wafer without too complicate power control of the heating lamp unit. The physical parameters in the visualization experiment include the temperature difference between the wafer and inlet air, inlet air flow rate, and pressure of the processing chamber. The flow photos taken from the processor installed with the uniformly perforated showerhead indicate that at a lower buoyancy-to-inertia ratio, the plug flow dominates in the processing chamber and no vortex roll appears above the wafer. While at a high buoyancy-to-inertia ratio the chamber is occupied by a big buoyancy induced circular vortex roll. We noted a mixed vortex flow consisting of both plug flow and a buoyancy induced vortex roll at an intermediate buoyancy-to-inertia ratio. Reducing the chamber pressure is found to be rather effective in eliminating the buoyancy induced vortex roll. When the processor is installed with the nonuniformly perforated showerhead, we can have two circular vortex rolls above the wafer at a certain buoyancy-to-inertia ratio. Moreover, the plug flow only exists for an unheated wafer. Hence the nonuniform showerhead does not improve the flow distribution over the wafer. In fact, the resulting flow distribution is poorer. We also provide empirical correlations to delineate the ranges of parameters for the appearance of various vortex flow patterns.
In the second part of the experiment, the air cooling of the copper plate placed right below the wafer is shown to significantly improve the wafer temperature uniformity in the ramp-down period for low and intermediate backside cooling air flow rates. Raising the input air flow rate to the processor also effectively improves the wafer temperature uniformity for the air flow rate up to some intermediate level. Besides, increasing the gas flow rate directly input to the processor or the backside air flow rate for the copper plate cooling also substantially speeds up the ramp-down rate of the wafer temperature.

ABSTRACT IN CHINESE i
ABSTRACT IN ENGLISH iii
TABLE OF CONTENTS vi
LIST OF TABLES ix
LIST OF FIGURES x
NOMENCLATURE xxii
CHAPTER 1 INTRODUCTION 1
1.1 Motivation of the Present Study 1
1.2 Literature Review 2
1.3 Objectives and Scope of Present Study 9
CHAPTER 2 EXPERIMENTAL APPARATUS AND PROCEDURES 11
2.1 Processing Chamber 11
2.2 Temperature Measurement and Data Acquisition Unit 12
2.3 Heating Lamp Unit 12
2.4Gas Injection Unit 13
2.5 Vacuum Unit 13
2.6 Control Unit 14
2.7 Experimental Procedures 14
2.8 Method to Improve Wafer Temperature Uniformity during Ramp-down Period 15
2.9 Uncertainty Analysis 24
CHAPTER3 GAS FLOW PATTERNS IN THE PROCESSING CHAMBER WITH A UNIFORMLY PERFORATED SHOWERHEAD 29
3.1 Typical Flow Patterns 29
3.2 Effects of Gas Flow Rate 31
3.3 Effects of Wafer-Inlet Air Temperature Difference 32
3.4 Effects of Chamber Pressure 33
3.5 The Flow Regime Map 34
3.6 Concluding Remarks for Uniformly Perforated Showerhead 35
CHAPTER 4 GAS FLOW PATTERNS IN THE PROCESSING CHAMBER WITH A NONUNIFORMLY PERFORATED SHOWERHEAD 81
4.1 Typical Flow Patterns 81
4.2 Effects of Gas Flow Rate 82
4.3 Effects of Wafer to Inlet Air Temperature Difference 83
4.4 Effects of Chamber Pressure 83
4.5 Flow Regime Map 84
4.6 Concluding Remarks 84
CHAPTER 5 IMPROVEMENT IN WAFER TEMPERATURE UNIFORMITY IN RAMP-DOWN PERIOD WITH COLD PLATE 119
5.1 Uniformity of Wafer Temperature 119
5.2 Ramp-Down Rate of Wafer 123
5.3 Concluding Remarks 124
CHAPTER 6 CONCLUDING REMARKS AND FUTURE WORK 157
6.1 Concluding Remarks ]
6.2 Future Work 159
REFERENCES 161

1. F. Roozeboom, Advances in rapid thermal and integrated processing, Kluwer Academic Publishers (1996).
2.C. P. Yin, C.C. Hsiao and T. F. Lin, Improvement in wafer temperature uniformity and flow pattern in a lamp heated rapid thermal processor, Journal of Crystal Growth, 217 (1-2) (2000) 201-210.
3.R. Gardon and J. C. Akfirat, The role of turbulence in determining the heat-transfer characteristics of impinging jets, Int. J. Heat Mass Transfer 8 (1965) 1261-1272.
4.R. Gardon and J. C. Akfirat, Heat transfer characteristics of impinging two-dimensional air jets, ASME Transac. C, J. Heat Transfer, (1966) 101-108.
5.M. T. Scholtz and O. Trass, Mass transfer in a nonuniform impinging jet, AIChE J., 16 (1970) 82-96.
6.E. M. Sparrow and T. C. Wong, Impingment transfer coefficients due to initially laminar slot jets, Int. J. Heat Mass Transfer, 18 (1975) 597-605.
7.J. H. Masliyah and T. T. Nguyen, Mass transfer due to an impinging slot jet, Int. J. Heat Mass Transfer, 22 (1979) 237-244.
8.P. Hrycak, Heat transfer from round impinging jets to a plat plate, Int. J. Heat Mass Transfer, 26, (1981) 1857-1865.
9.Ì. B. Özdermir and J. H. Whitelaw, Impingement of an axisymmetric jet on unheated and heated flat plates, J. Fluid Mech., 240 (1992) 503-532.
10.T. Liu and J. P. Sullivan, Heat transfer and flow structures in an excited circular impinging jet, Int. J. Heat Mass Transfer, 39 (1996) 3695-3706.
11.R. Viskanta, Heat transfer to impinging isothermal gas and flame jets, Expl. Thermal Fluid Sci., 6 (1993) 111-134.
12.K. Jambunathan, E. Lai, M. A. Moss and B. L. Button, A review of heat transfer data for single circular jet impingment, Int. J. Heat and Fluid Flow, 13 (2) (1992) 106-115.
13.Martin H, Impinging jet flow heat and mass transfer, Advances in Heat Transfer, Academic Press, 1-59.
14.C. Carcasci, An experimental investigation on air impinging jets using visualization methods, Int. J. Therm. Sci., 38 (1999) 808-818.
15.H. Elbanna and J. A. Sabbagh, Fow visualization and measurements in a two-dimensional two-impinging-jet flow, AIAA Journal, 27 (4) (1988) 418-426.
16.G. H. Moustafa and E. Rathakrishnan, Studies on the flowfield of multijet with square configuration, AIAA Journal, 31 (7) (1993) 189-1191.
17.S. C. Arjocu and J. A. Liburdy, Near surface characterization of an impinging elliptic jet array, ASME Transac., J. Heat Transfer, 121 (1999) 384-390.
18.E. Villermaux and E. J. Hopfinger, Periodically arranged co-flowing jets, J. Fluid Mech., 263 (1994) 63-92.
19.M. C. Özturk, F. Y. Sorrell, J. J. Wortman, F. S. Johnson, and D. T. Grider, Manufacturability issues in rapid thermal chemical vapor deposition, IEEE Trans. of Semiconductor Manufacturing, 4 (2) (1991) 155-165.
20.C. R. Biber, C. A. Wang, and S. Motakef, Flow regime map and deposition rate in vertical rotating-disk OMVPE reactor, Journal of Crystal Growth 123 (1992) 545-554.
21.C. Weber and V. C. Opdrop, Modeling of gas flow patterns in a symmetric vertical Vapor-Phase-Expitaxy reactor allowing asymmetric solution, J. Appl. Phys., 67 (1990) 109-2118.
22.D. I. Fotiads, and S. Kieda, Transport phenomena in vertical reactors for metalorganic vapor phase epitaxy, Journal of Crystal Growth, 102 (1990) 441-470.
23.C. R. Kleijn, Th. H. van der Meer, and Hoogendoorn, C. J., A Mathematical model for LPCVD in a single wafer reactor, J. Electrochem. Soc., 136 (11) (1989) 3423-3433.
24.S. Patnaik, R. A. Brown, and C. A. Wang, Hydrodynamic dispersion in rotating-disk OMVPE reactors: Numerical simulation and experimental measurements, Journal of Crystal Growth, 96 (1989) 153-174.
25.C. R. Biber, C. A. Wang, and S. Motakef, Flow regime map and deposition rate in vertical rotating-disk OMVPE reactor, Journal of Crystal Growth, 123 (1992) 545-554.
26.H. Caquineau and B. Despax, Influence of the reactor design in the case of silicon nitride PECVD, Chemical Engineering Science, 52 (17) (1997) 2901-2914.
27.C. R. Kleijn, K. J. Kuijlaars and H. E.A. Van Den Akker, Design and scale-up of chemical vapor deposition reactors for semiconductor processing, Chemical Engineering Science, 51 (10) (1996) 2119-2128.
28.D. Lytle, and B. W. Webb, Air Jet Impingement heat transfer at low nozzle-plate spacings, Int. J. Heat and Mass Transfer, 37 (12) (1994) 1687-1697.
29.A. H. Dilawari, and J. Szekely, A mathemical representation of a modified stagnation flow reactor for MOCVD application, Journal of Crystal Growth, 108 (1991) 491-498.
30.G. Wahl, Hydrodynamic description of CVD processes, Thin Solid Film, 40 (1977) 13-26.
31.W. K. Cho, D. H. Choi and M. —U. Kim, Optimization of the inlet velocity profile for uniform epitaxial growth in a vertical metalorganic chemical vapor deposition reactor, Int. J. of Heat and Mass Transfer, 42 (1999) 4143-4152.
32.H. V. Santen, C. R. Kleijn and H. E.A. V. D. Akker, Symmetry breaking in a stagnation-flow CVD reactor, Journal of Crystal Growth, 212 (2000) 311-323.
33.G. Evan, R. Grief, A numerical model of the flow and heat transfer in a rotating disk chemical vapor deposition reactor, Journal of Heat Transfer, 109 (1987) 928-935.
34.W. S. Winter, G. H. Evans, R. Grief, Mixed binary convection in rotating disk chemical vapor deposition reactor, International Journal of Heat and Mass Transfer 40(3) (1997) 737-744.
35.P. N. Gadgil, Optimization of a stagnation point flow reactor design for metalorganic chemical vapor deposition by flow visualization, Journal of Crystal Growth, 134(1993) 302-312.
36.Y. Kusumoto, T. Hayashi and S. Komiya, Numerical analysis of the transort phenomena in MOCVD process, Japanese Journal of Applied Physics, 24 (5) (1985) 620-625.
37.P. N. Gadgil, Single wafer processing in stagnation point flow CVD reactor: prospects, constrains and reactor design, Journal of Electronic Materials, 22 (2) (1993) 171-177.
38.I. Kim and D. G. Chang and P. D. Dapkus, Growth of InGaAsP in a stagnation flow vertical reactor using TBP and TBA, Journal of Crystal Growth, 195 (1998) 138-143.
39.R. Detaton, and H. Z. Massoud, Effect of thermally induced stresses on the rapid thermal oxidation, J. Appl. Phys. 70 (7) (1991) 3588-3592.
40.H. A. Lord, Thermal and stress analysis of semiconductor wafer in a rapid thermal processing oven, IEEE Trans. of Semiconductor Manufacturing, 1 (3) (1988) 105-114.
41.P. Vandenabeele, and K. Maex, Temperature control and temperature uniformity during rapid thermal processing, Mat. Res. Soc. Symp. Proc., 224 (1991) 185-196.
42.P. Vandenabeele, K. Maex and R. D. Keersmaecker, Rapd thermal annealing / chemical vapor deposition and integrated processing, Mat. Res. Soc. Symp. Proc., 146 (1989) 149-160.
43.B. Feil, M. Daw, and J. Moench, First International Rapid Thermal Processing Conference, Monterey, Scottsdale, AZ, 114 (1993).
44.J. F. Buller, M. Farahani, and S. Grag, Second International Rapid Thermal Processing Conference, Monterey, CA, 52 (1994).
45.R. P. S. Thakur, A. Martin, W. T. Fackrell, and R. Barbour, Stress and warpage studies of silicon and patterned films during rapid thermal processing (RTP), Mat. Res. Soc. Symp. Proc., 303 (1993) 189-195.
46.S. M. Hu, Stress-related problems in silicon technology, J. Appl. Phys., 70 (6) (1991) 53-80.
47.J. P. Hebb, K. F. Jensen and E.W. Egan, The potential effect of multilayer pattern on temperature uniformity during rapid thermal processing, Mat. Res. Soc. Symp. Proc., 387 (1995) 21-27.
48.J. M. Dihac, N. Nolhier, C. Ganibal and C. Zanchi, Thermal modeling of a Wafer in a rapid thermal processor, IEEE Trans. of Semiconductor Manufacturing, 8 (4) (1995) 432-439.
49.A. Tillmann, S. Buschbaum, S. Frigge, U. Kreiser, D. Löfelmacher, T. Theilig and P. Schmid, Modeling and off-line optimization of a 300 mm rapid thermal processing system, Materials Science in Semiconductor Processing, 1 (1998) 181-186.
50.S. M. Hu, Temperature distribution and stress in circular wafers in a row during radiative cooling, J. Appl. Phys., 10 (11) (1969) 4413-4423.
51.R. Deaton and H. Z. Massoud, Effect of thermally induced stresses on the raid-thermal oxidation of silicon, J. Appl. Phys., 10 (11) (1969) 4413-4423.
52.F. Y. Sorrell, M. J. Fordham, M. C. Özturk and J. J. Wortman, Temperature uniformity in RTP furances, IEEE Trans. of Electron Devices, 39 (1) (1992) 75-80.
53.R. Kakoschke and E. Bubmann, Simulation of temperature effects during rapid rhermal processing, Mat. Res. Soc. Symp. Proc. 146 (1989) 473-482.
54.T. J. Riley, and R. S. Gyurcsik, Rapid thermal processor modeling, control, and design for temperature uniformity, Mat. Res. Soc. Symp. Proc., 303 (1993) 223-229.
55.R. Kakoshke, E. Bubmann, and H. Foll, Modeling of wafer heating during rapid thermal processing, Appl. Phys. A50 (2) (1990) 141-150.
56.Y. M. Cho, A. Paulraj, T. Kailath and G. H. Xu, A contribution to optimal lamp design in rapid thermal processing, IEEE Trans. Semicond. Manuf., 7 (1) (1991) 34-41.
57.S. J. Kline, and F. A. Mcclintock, Describing uncertainties in single-sample experiment, Mechanical Engineering 75 (1953) 3-8.
58.R. J. Moffat, Contributions to the theory of single-sample uncertainty analysis, J. Fluid Eng., 104 (1982) 250-260.
59.Thermophysical properties of fluid, JSME Data Book (1983).
60.F. K. White, Viscous fluid flow, McGraw-Hill, New York, 2nd ed.(1991) pp.298-304.
61.A. H. Dilawari, and J. Szekely, A Mathemical representation of a modified stagnation flow reactor for MOCVD application, Journal of Crystal Growth, 108 (1991) 491-498.
62.G. Hahl, Hydrodynamic description of CVD processes, Thin Solid Film, 40 (1977) 13-26.