Method and apparatus for forming a planarizing pad having a film and texture elements for planarization of microelectronic substrates Number:7,151,056 from the United States Patent and Trademark Office (PTO) owispatent

Title: Method and apparatus for forming a planarizing pad having a film and texture elements for planarization of microelectronic substrates

Abstract: A planarizing pad for planarizing a microelectronic substrate, and a method and apparatus for forming the planarizing pad. In one embodiment, planarizing pad material is mixed with compressed gas to form a plurality of discrete elements that are distributed on a film support material. The film support material is supported by a liquid and is drawn from the liquid with a backing layer. At least a portion of the discrete elements are spaced apart from each other on the film support material to form a textured surface for engaging a microelectronic substrate and removing material from the microelectronic substrate. The discrete elements can be uniformly or randomly distributed on the film support material.

Patent Number: 7,151,056 Issued on 12/19/2006 to Meikle

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Inventors:	Meikle; Scott G. (Boise, ID)
Assignee:	Micron Technology, In.c (Boise, ID)
Appl. No.:	10/662,901
Filed:	September 15, 2003

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Related U.S. Patent Documents

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	Application Number	Filing Date	Patent Number	Issue Date
	09649427	Aug., 2000	6838382

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Current U.S. Class:	438/691 ; 438/692; 438/693
Current International Class:	H01L 21/302 (20060101)
Field of Search:	438/691,692,693 451/41 216/88,89 156/345.12

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Primary Examiner: Vinh; Lan
Attorney, Agent or Firm: Perkins Coie LLP

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Parent Case Text

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CROSS-REFERENCE TO RELATED APPLICATION

This application is a divisional application of U.S. patent application Ser. No. 09/649,427 entitled "METHOD AND APPARATUS FOR FORMING A PLANARIZING PAD HAVING A FILM AND TEXTURE ELEMENTS FOR PLANARIZATION OF MICROELECTRONIC SUBSTRATES," filed on Aug. 28, 2000 now U.S. Pat. No. 6,838,382, which is incorporated herein by reference in its entirety.

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Claims

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The invention claimed is:

1. A method for forming a textured planarizing pad, comprising: floating a film of a support material on a supporting liquid; separating a planarizing pad material into discrete elements; distributing the discrete elements in and/or on the support material floated on the supporting liquid; and drawing the support material and the discrete elements from the supporting liquid by engaging the support material with a backing material and moving the backing material away from the liquid.

2. The method of claim 1, further comprising separating the planarizing pad material into discrete elements and mixing the discrete elements with the support material before disposing the support material on a surface of the supporting liquid.

3. The method of claim 1, further comprising selecting the support material to include an organic Langmuir-Blodgett film material.

4. The method of claim 1, further comprising selecting the supporting liquid to include water.

5. The method of claim 1, further comprising disposing the discrete elements onto the support material after disposing the support material on the liquid.

6. The method of claim 1, further comprising disposing the support material on a surface of the supporting liquid to a thickness of one molecule.

7. The method of claim 1, further comprising: engaging the planarizing pad with a microelectronic substrate; and moving at least one of the planarizing pad and the microelectronic substrate relative to the other to remove material from the microelectronic substrate.

8. The method of claim 7, further comprising separating the planarizing pad material into discrete elements and mixing the discrete elements with the support material before disposing the support material on a surface of the support liquid.

9. The method of claim 7, further comprising selecting the support material to include an organic Langmuir-Blodgett film material.

10. The method of claim 7, further comprising disposing the discrete elements onto the support material after disposing the support material on the liquid.

11. The method of claim 7, further comprising disposing a planarizing liquid between a planarizing surface of the planarizing pad and a surface of the microelectronic substrate.

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Description

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TECHNICAL FIELD

This invention relates to planarizing pads and methods and apparatuses for forming planarizing pads for planarizing microelectronic substrates.

BACKGROUND OF THE INVENTION

Mechanical and chemical-mechanical planarization processes (collectively "CMP") are used in the manufacturing of electronic devices for forming a flat surface on semiconductor wafers, field emission displays and many other microelectronic-device substrate assemblies. CMP processes generally remove material from a substrate assembly to create a highly planar surface at a precise elevation in the layers of material on the substrate assembly. FIG. 1 schematically illustrates an existing web-format planarizing machine 10 for planarizing a substrate 12. The planarizing machine 10 has a support table 14 with a top-panel 16 at a workstation where an operative portion "A" of a planarizing pad 40 is positioned. The top-panel 16 is generally a rigid plate to provide a flat, solid surface to which a particular section of the planarizing pad 40 may be secured during planarization.

The planarizing machine 10 also has a plurality of rollers to guide, position and hold the planarizing pad 40 over the top-panel 16. The rollers include a supply roller 20, idler rollers 21, guide rollers 22, and a take-up roller 23. The supply roller 20 carries an unused or pre-operative portion of the planarizing pad 40, and the take-up roller 23 carries a used or post-operative portion of the planarizing pad 40. Additionally, the left idler roller 21 and the upper guide roller 22 stretch the planarizing pad 40 over the top-panel 16 to hold the planarizing pad 40 stationary during operation. A motor (not shown) drives at least one of the supply roller 20 and the take-up roller 23 to sequentially advance the planarizing pad 40 across the top-panel 16. Accordingly, clean pre-operative sections of the planarizing pad 40 may be quickly substituted for used sections to provide a consistent surface for planarizing and/or cleaning the substrate 12.

The web-format planarizing machine 10 also has a carrier assembly 30 that controls and protects the substrate 12 during planarization. The carrier assembly 30 generally has a substrate holder 32 to pick up, hold and release the substrate 12 at appropriate stages of the planarizing process. Several nozzles 33 attached to the substrate holder 32 dispense a planarizing solution 44 onto a planarizing surface 42 of the planarizing pad 40. The carrier assembly 30 also generally has a support gantry 34 carrying a drive assembly 35 that can translate along the gantry 34. The drive assembly 35 generally has an actuator 36, a drive shaft 37 coupled to the actuator 36, and an arm 38 projecting from the drive shaft 37. The arm 38 carries the substrate holder 32 via a terminal shaft 39 such that the drive assembly 35 orbits the substrate holder 32 about an axis B--B (as indicated by arrow "R.sub.1"). The terminal shaft 39 may also rotate the substrate holder 32 about its central axis C--C (as indicated by arrow "R.sub.2").

The planarizing pad 40 and the planarizing solution 44 define a planarizing medium that mechanically and/or chemically-mechanically removes material from the surface of the substrate 12. The planarizing pad 40 used in the web-format planarizing machine 10 is typically a fixed-abrasive planarizing pad in which abrasive particles are fixedly bonded to a suspension material. In fixed-abrasive applications, the planarizing solution is a "clean solution" without abrasive particles. In other applications, the planarizing pad 40 may be a non-abrasive pad without abrasive particles. The planarizing solutions 44 used with the non-abrasive planarizing pads are typically CMP slurries with abrasive particles and chemicals.

To planarize the substrate 12 with the planarizing machine 10, the carrier assembly 30 presses the substrate 12 against the planarizing surface 42 of the planarizing pad 40 in the presence of the planarizing solution 44. The drive assembly 35 then orbits the substrate holder 32 about the axis B--B, and optionally rotates the substrate holder 32 about the axis C--C, to translate the substrate 12 across the planarizing surface 42. As a result, the abrasive particles and/or the chemicals in the planarizing medium remove material from the surface of the substrate 12.

The CMP processes should consistently and accurately produce a uniformly planar surface on the substrate 12 to enable precise fabrication of circuits and photopatterns. During the fabrication of transistors, contacts, interconnects and other features, many substrates and/or substrate assemblies develop large "step heights" that create a highly topographic surface across the substrate assembly. Yet, as the density of integrated circuits increases, it is necessary to have a planar substrate surface at several intermediate stages during the fabrication of devices on a substrate assembly because non-uniform substrate surfaces significantly increase the difficulty of forming sub-micron features. For example, it is difficult to accurately focus photo patterns to within tolerances approaching 0.1 micron on non-uniform substrate surfaces because sub-micron photolithographic equipment generally has a very limited depth of field. Thus, CMP processes are often used to transform a topographical substrate surface into a highly uniform, planar substrate surface.

One conventional approach for improving the uniformity of the microelectronic substrate 12 is to engage the microelectronic substrate 12 with a planarizing pad 40 having a textured planarizing surface 42. For example, as shown in FIG. 2, the planarizing pad 40 can include spaced-apart texture elements 41. The texture elements 41 can improve the planarization of the microelectronic substrate 12 (FIG. 1) by retaining the planarizing liquid 44 (FIG. 1) in the interstices between the texture elements. Accordingly, the texture elements 41 increase the amount of planarizing liquid in contact with the microelectronic substrate 12 and increase the planarizing rate and surface uniformity of the microelectronic substrate 12.

One conventional method for forming the texture elements 41 is to engage a mold 50 with the planarizing pad 40 while the planarizing pad 40 is in a semi-solid or plastic state. For example, the mold 50 can include columnar apertures 51 that produce corresponding columnar texture elements 41 in the planarizing pad 40. One drawback with the foregoing fabrication method is that the mold 50 may deform the texture elements 41 as the mold 50 is withdrawn from the planarizing pad 40. For example, the planarizing pad material may adhere to the mold 50 or portions of the mold 50 such that the upper surfaces of the texture elements 41 develop sharp edges or other asperities 43. The asperities 43 can scratch or otherwise damage the microelectronic substrate 12 during planarization.

SUMMARY

The present invention is directed toward methods and apparatuses for forming planarizing media for planarizing microelectronic substrates. A method in accordance with one aspect of the invention includes separating a planarizing medium material into discrete elements and disposing the discrete elements and a liquid film support material on a support liquid. The support material and the discrete elements are drawn from the support liquid with a backing material. In a further aspect of this method, the film support material can be removed after attaching the discrete elements to backing material. Alternatively, the film support can be engaged with the backing material. In either embodiment, the discrete elements can be disposed on the film support material so that portions of the discrete elements are spaced apart from each other and project from the support material. The discrete elements are configured to engage the microelectronic substrate and to remove material from the microelectronic substrate when the microelectronic substrate contacts the discrete elements and at least one of the planarizing pad and the microelectronic substrate is moved relative to the other.

In one aspect of the invention, at least a portion