Optics: measuring and testing – Dimension – Thickness
Reexamination Certificate
2001-12-21
2004-09-28
Stafira, Michael P. (Department: 2877)
Optics: measuring and testing
Dimension
Thickness
Reexamination Certificate
active
06798529
ABSTRACT:
BRIEF DESCRIPTIONS OF THE INVENTION
The present invention relates to an in-situ method and apparatus for end point detection during chemical mechanical polishing, and more particularly to a method and apparatus in which localized areas of the surface of a semiconductor wafer or substrate which is undergoing chemical mechanical polishing are monitored to detect the removal of material from the localized wafer surface areas.
RELEVANT LITERATURE
The following literature references describe chemical mechanical polishing and various prior art end point detecting techniques.
Bahar, E., 1981, “Scattering Cross Sections for Composite Random Surfaces: Full Wave Analysis,”
Radio Sci.
, Vol. 16, pp. 1327-1335.
Bakin, D. V., Glen, D. E., and Sun, M. H., 1998, “Application of Backside Fiber-Optic System for In situ CMP Endpoint Detection on Shallow Trench Isolation Wafers,”
Proc. of SPIE
, Vol. 3507, pp. 210-207.
Banet, M. J., Fuchs, M., Rogers, J. A., Reinold, J. H., Knecht, J. M., Rothschild, M., Logan, R., Maznev, A. A., and Nelson, K. A., 1998, “High-Precision Film Thickness Determination Using a Laser-Based Ultrasonic Technique,”
Appl. Phys. Lett.
, Vol. 73, pp. 169-171.
Beckage, P. J., Lukner, R., Cho, W., Edwards, K., Jester, M., and Shaw, S, 1999, “Improved Metal CMP Endpoint Control by Monitoring Carrier Speed Controller Output or Pad Temperature,”
Proc. of SPIE
, Vol. 3882, pp. 118-125.
Bibby, T. and Holland, K., 1998, “Endpoint Detection in CMP,”
J. Electronic Materials
, Vol. 27, pp. 1073-1081.
Bibby, T., Adams, J. A., and Holland, K., 1999, “Optical Endpoint Detection for Chemical Mechanical Planarization,”
J. Vac. Sci. Technol. B
, Vol. 17, pp. 2378-2384.
Chan, D. A., Swedek, B., Wiswesser A., and Birang, M., 1998, “Process Control and Monitoring with Laser Interferometry Based Endpoint Detection in Chemical Mechanical Planarization,” 1998
IEEE/SEMI Advanced Semiconductor Mfg. Conf. and Workshop
, pp. 377-384.
Desanto, J. A., 1975, “Scattering from a Perfectly Reflecting Arbitrary Periodic Surface: An Exact Theory,”
Radio Sci.
, Vol. 16, pp. 1315-1326.
Desanto, J. A., 1981, “Scattering from a Sinusoid: Derivation of Linear Equations for the Field Amplitudes,”
J. Acoustical Soc. Am.
, Vol. 57, pp. 1195-1197.
Drain, D., 1997
, Statistical Methods for Industrial Process Control
, Chapman and Hall, New York.
Eckart, C., 1933, “A general Derivation of the Formula for the Diffraction by a Perfect Grating,”
Physical Review
, Vol. 44, pp. 12-14.
Fang, S. J., Barda, A., Janecko, T., Little, W., Outley, D., Hempel, G., Joshi, S., Morrison, B., Shinn, G. B., and Birang, M., 1998, “Control of Dielectric Chemical Mechanical Polishing (CMP) Using an Interferometry Based Endpoint Sensor,”
Proc. IEEE
1998
International Interconnect Technol. Conf.
, pp. 76-78.
Joffe, M. A., Yeung, H., Fuchs, M., Banet, M. J., and Hymes, S., 1999, “Novel Thin-Film Metrology for CMP Applications,”
Proc.
1999
CMP
-
MIC Conf.
, pp. 73-76.
Leach, M. A., Machesney, B. J., and Nowak, E. J., U.S. Pat. No. 5,213,655, May 25, 1993.
Litvak, H. E. and Tzeng, H.-M., 1996, “Implementing Real-Time Endpoint Control in CMP,”
Semiconductor International
, Vol., pp. 259-264.
Marcoux, P. J. and Foo, P. D., 1981, “Methods of End Point Detection for Plasma Etching,”
Solid State Technology
, Vol., pp. 115-122.
Montgomery, D. C., 1996
, Introduction to Statistical Quality Control,
3rd ed., John Wiley & Sons., Inc., New York, pp. 101-111.
Murarka, S., Gutmann, R., Duquette, D., and Steigerwald, J, U.S. Pat. No. 5,637,185, Jun. 10, 1997.
Lord Rayleigh, 1907, “On the Dynamical Theory of Gratings,”
Proc. Roy. Soc., A,
Vol. 79, pp. 399-416.
Park, T., Tugbawa, T., Boning, D., Chung, J., Hymes, S., Muralidhar, R., Wilks, B., Smekalin, K., Bersuker, G., 1999, “Electrical Characterization of Copper Chemical Mechanical Polishing,”
Proc.
1999
CMP
-
MIC Conf.
, pp. 184-191.
Rogers, J. A., Fuchs, M., Banet, M. J., Hanselnan, J. B., Logan, R., and Nelson, K. A., 1997, “Optical System for Rapid Materials Characterization with Transient Grating Technique: Application to Nondestructive Evaluation of Thin Films Used in Microelectronics,”
Appl. Phys. Lett.
, Vol. 71(2), pp. 225-227.
Sachs, L.,
Applied Statistics: A Handbook of Techniques
, translated by Reynarowych, Z., Springer-Verlag, New York.
Sandhu, G., Schultz, L., and Doan, T., U.S. Pat. No. 5,036,015, Jul. 30, 1991.
Schultz, L., U.S. Pat. No. 5,081,796, Jan. 21, 1992.
Smith, W. L., Kruse, K., Holland, K., and Harwood, R., 1996, “Film Thickness Measurements for Chemical Mechanical Planarization,”
Solid State Technol.
, Vol., pp. 77-86.
Steigerwald, J. M., Zirpoli, R., Murarka, S. P., Price, D. and Gutmann, R. J., 1994, “Pattern Geometry Effects in the Chemical-Mechanical Polishing of Inlaid Copper Structures,”
J. Electrochem. Soc.
, Vol. 141, pp. 2842-2848.
Stine, B. E., 1997, “A General Methodology for Acessing and Characterizing Variation in Semiconductor Manufacturing”, Ph.D. Thesis, Massachusetts Institute of Technology.
Stien, D. J. and Hetherington, D. L., 1999, “Prediction of Tungsten CMP Pad Life Using Blanket Romoval Rate Data and Endpoint Data Obtained from Process Temperature and Carrier Motor Current Measurements,”
Proc. of SPIE
, Vol. 3743, pp. 112-119.
Uretsky, J. L., 1965, “The Scattering of Plane Waves from Periodic Surfaces,”
Annals of Phys.
, Vol. 33, pp. 400-427.
Zeidler, D., Plotner, M., and Drescher, K., 2000, “Endpoint Detection Method for CMP of Copper,”
Microelectronic Engineering
, Vol. 50, pp. 411-416.
Zipin, R. B, 1966, “A Preliminary Investigation of Bidirectional Spectral Reflectance of V-Grooved Surfaces,”
Appl. Optics
, Vol. 5, pp. 1954-1957.
BACKGROUND OF THE INVENTION
Manufacture of semiconductors has become increasingly complex as the device densities increase. Such high density circuits typically require closely spaced metal interconnect lines and multiple layers of insulating material, such as oxides, formed atop and between the interconnect lines. Surface planarity of the semiconductor wafer or substrate degrades as the layers are deposited. Generally, the surface of a layer will have a topography that conforms to the sublayer, and as the number of layers increase the non-planarity of the surface becomes more pronounced.
To address the problem, chemical mechanical polishing (CMP) processes are employed. The CMP process removes material from the surface of the wafer to provide a substantially planar surface. More recently, the CMP process is also used to fabricate the interconnecting lines. For example, when depositing copper leads or interconnect lines, a full layer of the metal
13
is deposited on the surface of the wafer
10
having grooves
12
formed in an oxide layer
11
as shown in
FIGS. 1A and 1B
. The metal layer
13
may be deposited by sputtering or vapor deposition or by any other suitable conventional technique. The oxide layer, such as doped or undoped silicon dioxide, is usually formed by chemical vapor deposition (CVD). The metal layer covers the entire surface of the wafer and extends into the grooves. Thereafter, individual leads
16
are defined by removing the metal layer from the surface of the oxide. The CMP process may be used to remove the surface metal leaving the leads
16
in the grooves. The leads are insulated from one another by the intervening oxide layer.
In general, to carry out the CMP process, a chemical mechanical polishing (CMP) machines is used. Many types of CMP machines are used in the semiconductor industry. CMP machines typically employ a rotating polishing platen having a polishing pad thereon, and a smaller diameter rotating wafer carrier which carries the wafer whose surface is to be planarized and/or polished. The surface of the rotating wafer is held or urged against the rotating polishing pad. A slurry is fed to the surface of the polishing pad during polishing of the wafer.
It is desirable to precisely determine when the material has been removed from the upper surface of the wafer during the CMP process. This not only prevents discarding of over-polished wafers, but also min
Nam Jamie
Oh Hilario L.
Saka Nannaji
Aviza Technology Inc.
Stafira Michael P.
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