Semiconductor device manufacturing: process – Chemical etching – Combined with the removal of material by nonchemical means
Reexamination Certificate
2000-03-08
2002-01-08
Hiteshew, Felisa (Department: 1765)
Semiconductor device manufacturing: process
Chemical etching
Combined with the removal of material by nonchemical means
C051S295000, C051S298000, C051S302000
Reexamination Certificate
active
06337281
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to chemical-mechanical polishing systems for use in modifying a substrate by Hertzian indentation, fluid-based wear and/or any similar-type non-microgrinding mechanism; the polishing systems of the present invention are particularly well suited for use in the manufacture of semiconductor devices, memory disks or the like. More particularly, the compositions and methods of the present invention are directed to polishing systems comprising an aqueous based polishing fluid and a fixed abrasive polishing pad.
Definition of Terms
1. Polishing. “Polishing” is intended to mean chemical-mechanical polishing (as opposed to micro-grinding) and is intended to include planarization and any corresponding variations thereof. The polishing substrates contemplated by the present invention include semiconductor device substrates, such as, silicon, silica, gallium arsenide, silicon nitride, tungsten, tantalum, aluminum, copper, and any other semiconductor device substrate, whether conducting, semi-conducting or insulating.
2. Conditioning. In the art of chemical-mechanical polishing, conventional polishing pads generally must be conditioned or otherwise roughened to initially create, then periodically renew, the pad's polishing surface. Throughout this specification, “conditioning” is intended to mean mechanical and/or chemical surface treatment of a pad's polishing surface to generate nanoasperities.
3. Nanoasperities. Throughout this specification, “nanoasperities” are intended to mean:
i. protrusions from the pad surface; and/or
ii. particles which release from the pad surface, having an imputed radius (of curvature) of about 0.5 to about 0.1 microns and sufficient resiliency to permanently deform (measured by the permanent change in curvature during polishing) by less than 25%, more preferably less than 10%.
4. Macro-Defects. Throughout this specification, “macro-defects” are intended to mean burrs or similar-type protrusions on the pad's polishing surface of greater than 0.5 microns in any dimension.
5. Particles. For purposes of the present invention, “particle” is intended to mean a discrete mass of material as it exists at the polishing interface. Hence, a “particle” can mean an independent, discrete primary particle, an agglomeration of primary particles which form a discrete mass, and/or primary particles which are aggregated together to form a discrete mass. Particles may sometimes be described herein as “high modulus phase material” or “high modulus domains” or “discontinuous phase”.
6. Self-dressing. Self-dressing is intended to mean that the polishing layer abrades, dissolves, wears or otherwise diminishes during the polishing operation, and as it diminishes, new nanoasperities are formed at the polishing interface, whether the pad is periodically conditioned during its useful life or not.
7. Pre-polymer. “Pre-polymer” is intended to mean any polymer precursor, including an oligomer, monomer, reactive polymer (including cross-linkable or curable polymers) and/or the like.
2. Discussion of the Prior Art
Generally speaking, conventional fixed abrasive polishing systems are used for grinding or micro-grinding of substrates. This type of polishing has been found generally to be inappropriate for improving the planarity of substrates in the manufacture of semiconductor devices or memory disks. Hence conventional polishing systems in the manufacture of semiconductor devices or memory disks generally comprise free abrasive in a polishing fluid and a polishing pad devoid of fixed abrasives.
Such conventional polishing systems generally attempt to improve particle uniformity throughout the polishing interface by flowing large amounts of polishing slurries into the polishing interface and by using slurries with high loadings of abrasive particles. However with such conventional polishing systems, the substrate and polishing equipment generally require extensive cleaning after the polish. This cleaning step slows down production, is prone to operator error and can create environmental concerns.
A need therefore exists in the art for a polishing system which provides improved polishing uniformity along the polishing interface without the need for flowing large amounts of polishing slurries (having high particle loadings) into the polishing interface.
The prior art is exemplified by U.S. Pat. No. 4,343,910 to Busch, Jr. et al. This reference is directed to foamed polymeric materials having a finely divided abrasive. The abrasive has a particle size and a valley abrasion number, the product of which, must fall within a predetermined range; otherwise acceptable polishing is taught to be non-obtainable. Compositions in accordance with this prior art reference are problematic in the polishing of semi-conductor device substrates. Therefore, a need exists in the art for a fixed abrasive polishing system capable of meeting the rigorous polishing performance requirements of the semiconductor industry.
SUMMARY OF THE INVENTION
The present invention relates generally to an improved method of chemical-mechanical polishing of one or more substrates useful in the manufacture of semiconductor devices, memory disks or the like, including precursors thereto. In the practice of the present invention, an aqueous fluid (which may or may not contain abrasive particles) is placed between a substrate and a fixed abrasive pad. The fluid preferably provides a substantially consistent pH during polishing. The substrate to be polished is a precursor to a memory disk or a precursor to a semiconductor device.
The pad has a three dimensional fixed abrasive polishing layer. The polishing layer has a plurality of protrusions with recesses between the protrusions. The polishing layer protrusions comprise a plurality of nanoasperities. The polishing layer also contains a plurality of particles having an average particle size of less than 0.6 microns, whereby the average particle size multiplied by the particle's valley abrasion number is less than 300.
The polishing surface and the substrate surface are moved relative to and are biased toward one another as at least a portion of the fluid is maintained between the surfaces. The fluid between the surfaces acts to prevent at least 20% of the surfaces, on average, from touching one another during polishing.
The surfaces are biased together by applying a uniform pressure of less than 25 pounds per square inch. The polishing surface is compressed by less than 25 microns during polishing, more preferably less than 10 microns and most preferably less than 5 microns. The resulting chemically and mechanically polishing of the substrate surface increases surface planarity.
At least a portion of the particles are released (into the polishing interface) from the fixed abrasive pad during polishing, thereby creating nanoasperities at the polishing interface. The surface area of the fixed abrasive pad at the polishing interface varies by less than 10% during the polishing operation.
The polishing layer has a matrix material as a continuous phase or low modulus phase, and the particles as a discontinuous phase or high modulus phase, and the matrix material has the following properties:
i. a density greater than 0.5 g/cm
3
;
ii. a critical surface tension greater than or equal to 34 milliNewtons per meter;
iii. a tensile modulus of 0.02 to 5 GigaPascals;
iv. a ratio of tensile modulus at 30 degrees C. to tensile modulus at 60 degrees C. of 1.0 to 2.5;
v. a hardness of 25 to 80 Shore D;
vi. a yield stress of 300-6000 psi;
vii. a tensile strength of 1000 to 15,000 psi; and
viii. an elongation to break less than or equal to 500%.
The matrix material comprises at least one moiety from the group consisting of: 1. a urethane and/or urea; 2. a carbonate; 3. an amide; 4. an ester; 5. an ether; 6. an acrylate; 7. a methacrylate; 8. an acrylic acid; 9. a methacrylic acid; 10. a sulphone; 1. an acrylamide; 12. a halide; 13. an imide; 14. a carboxyl; 15. a carbonyl; 16. an amino; 17. an ald
Budinger William D.
Chechik Nina G.
James David B.
Levering, Jr. Richard M.
Oliver Michael R.
Benson Kenneth A.
Deo Duy-Vu
Hiteshew Felisa
Kaeding Konrad
Kita Gerald K.
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