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Apparatus, backing plate, backing film and method for chemical mechanical polishing

a technology of backing plate and backing film, applied in the direction of grinding machine, manufacturing tools, lapping machine, etc., can solve the problems of deteriorating the quality of lsis formed at the periphery of the wafer below the criteria, whole edge, and insufficient first idea

Inactive Publication Date: 2001-10-25
TOSHIBA MEMORY CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

This solution ensures uniform polishing rates across the wafer, maintaining the quality of LSIs at the periphery, improving yield, and reducing production costs by optimizing the polishing process.

Problems solved by technology

This, however, may deteriorate the quality of LSIs formed at the periphery of the wafer below criteria because the peripheral polishing rates are about 20% smaller than the others.
(1) A first idea is to use harder material for the polishing cloth 7 so that the polishing cloth 7 may not be deformed due to pressing force and friction. If the polishing cloth 7 is hard, it may unevenly contact and polish a wafer. Accordingly, the first idea is inadequate. The polishing cloth 7 must be soft to some extent.
(2) A second idea is that there will be an optimum value for the gap 15 between the guide 5 and the polishing cloth 7 in FIGS. 6A and 7A and that the optimum value will be between the gap 15 of FIG. 6A and that of FIG. 7A. If there is such an optimum gap, force with which the guide 5 pushes the polishing cloth 7 will be smaller than that of FIG. 7C. This force will vary, and therefore, a strongly compressed area of the polishing cloth 7 will move between under the wafer 1 and under the guide 5. This fluctuates polishing rates at the periphery of the wafer 1. Accordingly, the second idea is inadequate.
(3) A third idea is to enlarge the wafer base 13 with respect to the size of the wafer 1 so that the stretched area of the polishing cloth 7 of FIG. 7C may not reach the wafer 1. This, however, produces a highly compressed area not only under the guide 5 but also under the wafer 1. There will be an idea to adjust the edge of the stretched area of the polishing cloth 7 to the edge of the wafer 1. Adjusting the whole edge of the wafer 1 to the edge of the stretched area of the polishing cloth 7 is very difficult. In addition, a play between the guide 5 and the wafer 1 will increase. Accordingly, the third idea is inadequate.

Method used

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  • Apparatus, backing plate, backing film and method for chemical mechanical polishing
  • Apparatus, backing plate, backing film and method for chemical mechanical polishing
  • Apparatus, backing plate, backing film and method for chemical mechanical polishing

Examples

Experimental program
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Effect test

first embodiment

[0082] The first embodiment polishes a thermal oxidation film formed on an 8-inch silicon wafer 1.

[0083] The first embodiment employs the: polishing apparatus of FIG. 8A. The backing plate 4 is a disk having a diameter of about 201 mm and a thickness of about 9.1 mm. The backing film 2 is a circular film having a diameter of about 201 mm and a thickness of about 0.5 mm and made of urethane. The guide 5 is a cylinder having an inner diameter of 202 mm, an external diameter of about 220 mm, and a height of about 10 mm. The ring 3 has an inner diameter of 181 mm, an external diameter of 201 mm, a width of 10 mm, and a thickness of 30 .mu.m. The surface plate 8 has a diameter of 600 mm. The surface plate 8 and the polishing cloth 7 attached thereto are rotated at 50 rpm. The thickness of the polishing cloth 7 is about 4 mm. The abrasive 12 is supplied onto the polishing cloth 7 at 200 cc / min. The wafer 1 is set under the backing film 2 of the wafer base 13. The wafer base 13 is rotated ...

second embodiment

[0087] The second embodiment polishes a polysilicon film formed on an 8-inch silicon wafer.

[0088] The second embodiment employs the polishing apparatus of FIG. 8A with different rings. A first ring 3 has an inner diameter of 181 mm, an outer diameter of 201 mm, and a thickness of 50 .mu.m. A second ring 3 has an inner diameter of 191 mm, an outer diameter of 201 mm, and a sickness of 30 .mu.m. The surface plate 8 and polishing cloth 7 are rotated at 100 rpm. The abrasive 12 is supplied onto the polishing cloth 7 at 250 cc / min. The wafer 1 is set on the wafer base 13, which is rotated at 100 rpm and is pressed against the polishing cloth 7 under 300 g / cm.sup.2. The air 14 is pressurized to 150 g / cm.sup.2 to press a central part of the top of the wafer 1.

[0089] FIG. 16 is a graph showing polishing rates at various measurement points on the polysilicon film formed on the silicon wafer 1 of 200 mm in diameter polished with the first ring 3 and with both the wafer 1 and guide 5 pressed a...

third embodiment

[0091] The third embodiment polishes a tungsten (W) film formed on an 8-inch silicon wafer.

[0092] The third embodiment employs the polishing apparatus of FIG. 8A with different rings. A first ring 3 has an inner diameter of 181 mm, an outer diameter of 201 mm, a width of 10 mm, and a thickness of 30 .mu.m. A second ring 3 has an inner diameter of 151 .mu.mm, an outer diameter of 201 mm, a width of 25 mm, and a thickness of 30 .mu.m. A third ring 3 has an inner diameter of 151 mm, an outer diameter of 201 mm, a width of 25 mm, and a thickness of 35 .mu.m. A fourth ring 3 has an inner diameter of 191 mm, an outer diameter of 201 mm, a width of 5 mm, and a thickness of 60 .mu.m. The surface plate 8 and polishing cloth 7 are rotated at 100 rpm. The abrasive 12 is supplied onto the polishing cloth 7 at 200 cc / min. The wafer 1 is set on the wafer base 13, which is rotated at 50 rpm and is pressed against the polishing cloth 7 under 200 g / cm.sup.2. The air 14 is pressurized to 130 g / cm.sup...

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Abstract

A polishing apparatus has a guide (5) to be pressed against a polishing cloth (7) when polishing an object (1). Within the guide, a ring (3) is arranged between a backing plate (4) and a backing film (2). When the guide and polishing cloth are rotated to rub with each other, force of the periphery of the object of pressing the polishing cloth drops. The ring prevents such a force drop, thereby equalizing polishing rates over a surface of the object. Also provided is a polishing method applied to the polishing apparatus.

Description

[0001] 1. Field of the Invention[0002] The present invention relates to a polishing apparatus and a polishing method, and particularly, to the apparatus and the method for polishing semiconductor wafers based on a chemical mechanical polishing (CMP) technique. The present invention also relates to a backing plate and a backing film used by the polishing apparatus.[0003] 2. Description of the Related Art[0004] FIG. 1A is a top view showing a polishing apparatus according to a related art and FIG. 1B is a side view showing the same. The polishing apparatus is used for semiconductor device manufacturing for polishing and planarizing the steps in the surface of a semiconductor wafer due to devices and interconnections formed thereon. A disk-like surface plate 8 has a shaft 10 rotated by a driver (not shown). A polishing cloth 7 made of, for example, polyurethane foam is attached to the top of the surface plate 8. A port 11 supplies abrasive 12 onto the polishing cloth 7. A wafer base 13...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): B24B37/005B24B37/30H01L21/304
CPCB24B37/30
Inventor WATANABE, TOMOHARUKATO, NOBUHIRO
Owner TOSHIBA MEMORY CORP