JPH05129256A - Device and method of grinding semiconductor wafer - Google Patents

Abstract

PURPOSE: To provide a device for eliminating a by-product due to polishing, without interrupting the polishing process of a wafer by recovering a flat fiber on a pad that has been designed to polish the semiconductor wafer. CONSTITUTION: A device has a jet assembly 16 with an extension pipe 18 that is supported on a pad 10 for polishing. The jet assembly 16 recovers a fiber 14 by supplying a gas, such as air or a liquid to a fiber 14 on the pad 10 under constant conditions and at the same time, a by-product due to polishing is eliminated.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention is a fiber designed on a pad for polishing a semiconductor wafer, which recovers a fiber that is gradually flattened by polishing, and which is a byproduct and consumption of the polishing. A process and apparatus for removing abrasive material from the surface of a pad.

[0002]

BACKGROUND OF THE INVENTION In a semiconductor wafer manufacturing process, in order to selectively remove excess materials such as oxides, polysilicon, and aluminum from the surface of the wafer,
The wafer needs to be polished. Such polishing is
Called the "planarization technique," it supplies the wafer with the appropriate chemicals to selectively remove the outer layer of material from the surface, leaving the buried material to provide the wafer with the proper pattern. ..

To polish the wafer, the wafer is supported on a carrier and contacts a normally circular polishing pad. The polishing pad has an outer surface of polyethylene terephthalate (eg, MYLAR) and an extending fiber extending upwardly from the surface. The extension fiber is surface treated with a suitable chemical and brought into contact with the surface of the semiconductor wafer. Unwanted material is removed from the wafer as the fiber is moved across the surface of the wafer as the pad is rotated.

In the polishing process, the spent polishing material and byproducts will be embedded in the fibers of the polishing pad. In addition, the fiber tends to be flat against the polishing pad resulting in a "smoothing" effect on the surface of the pad. Flattened fibers and buried spent abrasive material and byproducts reduce the efficiency of the polishing process and extend the time required to polish a wafer. In fact, the pad eventually fills with by-products or otherwise becomes very smooth and loses any further polishing activity.

It is known that processes have been developed for reclaiming polishing pads. For example, direct pad contact means have been used, such as nylon brushes, sandpaper, or diamond surfaced blades. However, these processes generally require interrupting the wafer polishing process and, in some cases, removing the polishing pad from the polishing assembly. In addition, these treatments abrade the surface of the pad, so the polishing pad must still be replaced frequently, and in some cases only a few semiconductor wafers (eg, 10) should be replaced after they have been polished. There must be.

One technique developed for removing particles from the surface of a flat plate is described in US Pat. No. 3,031,195 to Lansford. This patent
Disclosed is an apparatus for removing particles from the surface of a musical record, where air is blown downwards through a tone arm toward the surface of the record, resulting in particle removal.

Other techniques have been developed to remove residue on polishing pads. These techniques are shown in U.S. Pat. No. 3,907,257 of Dulzewiecki and U.S. Pat. No. 3,754,359 of Skiandaretos. The Dulzewiecki patent shows a tubular housing designed to have a polishing pad wrapped around the circumference of the housing. A plurality of holes are formed in the housing to allow air to pass through the pad and remove residue. Similarly, the Skanderetos patent shows a perforated flexible disc designed to provide airflow through the through-hole when the disc is rotated. The air stream removes the residue on the surface of the disc.

The above-described examples disclosing techniques for removing residue or particles from a polishing pad generally require fluid to pass through the pad and can act on a pad having a backing support member. Rather than 1) recover the flattened fibers of the polishing pad, 2) simultaneously remove by-products and spent polishing material from the pad surface during the polishing process, and 3) interrupt the polishing process. It's not designed to do those things without. The present invention not only achieves all of this during proper polishing of each semiconductor wafer, but does so without frequent replacement of polishing pads and interruption of the polishing process at the same time.

[0009]

SUMMARY OF THE INVENTION It is an object of the present invention to recover a flattened fiber on a pad designed to polish a semiconductor wafer and also to remove byproducts of polishing without interrupting the wafer polishing process. An object is to provide a device for removing spent abrasive material from a pad.

Another object of the present invention is to provide a versatile device for removing polishing byproducts and spent polishing material from a polishing pad and for recovering a flattened fiber on the pad without contacting the pad. Is.

Yet another object of the present invention is to remove byproducts of polishing and spent abrasive material from the polishing pad,
It is an object of the present invention to provide an effective device for recovering a flattened polishing pad fiber on a pad. This device is simple and easy to operate, and further increases the number of semiconductor wafers that can be polished before replacement of the polishing pad is required.

[0012]

SUMMARY OF THE INVENTION The present invention provides a process and apparatus for raising a flattened fiber in a polishing pad, and a polishing pad for polishing a suitable semiconductor wafer. To remove by-products from polishing and spent polishing material. This device consists of a jet assembly having an extension pipe supported on a polishing pad. The jet assembly provides a downwardly directed flow of a fluid, such as air, toward the polishing pad. The air flow restores the flattened fibers on the pad, removing by-products of polishing and spent abrasive material during the polishing process.

The polishing pad is supported on a rotatable platen and is normally composed of a plurality of fibers extending substantially perpendicular to the upper surface of the polishing pad. The fiber is designed to be coated with a suitable chemical and contacts the surface of the semiconductor wafer, thus chemically and mechanically polishing the wafer as the platen is rotated.

The extension pipe of the air jet assembly is
It is supported on the polishing pad and extends radially inward toward the axis of rotation of the polishing pad. One end of the pipe
It has an inlet coupled to an air supply. A continuous outlet is formed along the length of the pipe and is angled downward with respect to the surface of the polishing pad. When the air supply is activated, air is forced through the outlet and directed at the surface of the rotating polishing pad. The air flow restores the flattened pad fiber in the normal direction, simultaneously removing spent abrasive material and byproducts from the pad.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Referring initially to FIGS.
The polishing pad indicated by is designed to polish the surface of a semiconductor wafer (shown at 11) during the wafer fabrication process. The polishing process and operation of the apparatus of the present invention are assigned to the assignee of the present invention, US Pat. No. 47938.
As shown in No. 95, chemical and mechanical flattening (CM
P) Shown to be related to processing. However, it will be appreciated that the apparatus and process of the present invention may be used in other processes that remove different materials such as oxides, polysilicon, and aluminum from the surface of semiconductor wafers.

The pad 10 is substantially circular in plane and is supported on a rotatable platen 12. The pad 10 is generally constituted by a number of extending fibers 14, which normally extend approximately perpendicular to the top surface of the pad surface for contacting and polishing the surface of the semiconductor wafer. Pad 10
Is lined with an impermeable surface 13 such as polyethylene terephthalate (eg MYLAR). During the polishing process, the chemicals with abrasives suitable for the material being polished are
It is continuously added to the pad in the form of a slurry to remove unwanted material from the wafer.

During the semiconductor wafer manufacturing process, the fiber 14 tends to flatten during the polishing process (see FIG. 3). In addition, polishing byproducts and spent polishing material tend to be embedded in the fibers of the pad. Also, a "smoothing effect" is clearly visible on the surface of the polishing pad. Flattened fiber and
The embedded polishing by-product and the consumed polishing material are
Reduces pad polishing efficiency.

In accordance with the present invention, an air jet assembly, indicated generally at 16, is supported in a spatial relationship on the surface of the polishing pad. Air jet assembly 1
6 has an extension pipe 18 connected to an air supply source 24 by a flexible tube 20.

The extension pipe 18 is formed of a rigid plastic or other suitable material and preferably extends radially inward toward the axis of rotation of the polishing pad. One end of the pipe 18 has an inlet 25 connected to the flexible tube 20, and the other end is closed by a cap 26. The pipe 18 of the air jet assembly can be pivotally attached to the platen support mechanism with a universal joint block (not shown). Thus, during replacement of the polishing pad, the pipe 18 can be moved away from the platen.

As shown in FIGS. 2 and 4, a plurality of through holes 28 are formed in the wall of the pipe 18. Each through hole 28 has a diameter D. The through openings are preferably of equal spacing d along the length of the pipe 18.
It is said that. The distance d between the edges of the through holes and the diameter of the perforations are preferably equal. Due to the above processing, the diameter D
It has been determined that the distance d and the distance d should be approximately 1/8 inch (0.32 cm). Alternatively, it is within the scope of the present invention to provide a narrow groove extending along the length direction of the pipe instead of the through hole.

The air supply 24 is of conventional design and provides compressed air (or other suitable gas or liquid) to the inlet 25 of the pipe 18 via the flexible tube 20. Air fills the pipe and is forced out through the through-hole 28 in a substantially uniform flow. Through-hole 28 directs air downwards at an angle φ with respect to the fibers on the polishing pad (FIG. 3), which angle is approximately 45 ° in the direction of platen rotation.

As platen 12 rotates, as more clearly shown in FIG. 3, as indicated generally by dashed line 29,
Chemicals are added to the fibers of the polishing pad via an applicator. As the polishing pad rotates, the fiber moves across the surface of the wafer. The chemicals on the fibers, along with the by-products of polishing, remove the polished abrasive that will be embedded in the fibers of the pad. In addition, the fibers on the pad become flat during contact with the surface of the wafer. A downwardly directed air stream is provided at an angle φ to the flattened fibers on the polishing pad 10. The air causes the polishing by-products and spent polishing material to be blown off the pad, causing the flattened fiber in a normal orientation such that it is approximately perpendicular to the surface of the polishing pad. Furthermore, "smoothing" of the fiber during polishing is avoided by blowing off this material and by-products of polishing. While the platen continues to rotate, the lifted fiber is again surface treated with chemicals to contact and polish the surface of the semiconductor wafer.

Tests were conducted using an air jet assembly supported on a polishing pad where an 8 inch semiconductor wafer was polished. The pad was spun on the platen at a rate of 35 rpm. The through-hole of the pipe provides air to the flattened fiber on the polishing pad at an angle of 45 ° and a gauge pressure of 4.4 atm (65 PSIG) in the direction of rotation. The air jet assembly was determined to remove spent abrasive material and byproducts from the pad, resulting in a flattened pad fiber. In addition, the air jet assembly has also been determined to extend the life of the polishing pad in the wafer polishing process. In particular, it was determined that one polishing pad was able to polish 500 semiconductor wafers before replacement when the air jet assembly was turned on. In contrast, it was found that when the air jet assembly was not operated, the polishing pad had to be replaced after only 40 wafers had been polished. The increase in pad life is therefore 1250%.

Although the present invention has been shown and described with respect to certain preferred embodiments, it can be adapted to other similar techniques in a manner that is based on an understanding of the specification. For example, water, solvents, polishing fluids, such fluids can replace the air described above.

[0025]

The present invention thus provides an air jet device that is simple and easy to operate and that efficiently removes spent abrasive material and byproducts from the surface of the polishing pad.
In addition, the apparatus provides for orienting the flattened fiber of the polishing pad for proper polishing of the semiconductor wafer in the wafer fab process.

[Brief description of drawings]

FIG. 1 is disposed on a polishing pad according to the present invention,
It is a top view of an air jet device.

2 is a vertical cross-sectional view of the air jet device and the polishing pad taken along the line 2-2 in FIG.

3 is a cross-sectional view of the air jet device and polishing pad taken along line 3-3 of FIG.

FIG. 4 is an enlarged view of a portion of the air jet device shown in FIG.

[Explanation of symbols]

 10 Polishing Pad 11 Wafer 12 Platen 14 Fiber 16 Air Jet Assembly 18 Pipe 24 Air Supply Source

Front Page Continuation (72) Inventor James A Richards Day, South Street, Earl, USA, Earl 1 Box 311-3, South Hero, Vermont, USA

Claims (10)

[Claims] 1. A rotatable platen, a polishing pad supported on the platen, and an extension pipe supported with a space with respect to the polishing pad. The fiber having a fiber extending substantially perpendicular to the surface of the polishing pad and tending to be flat against the surface during polishing of a semiconductor wafer; the extension pipe having an inlet and an outlet; Coupled to a source, the outlet is directed toward the surface of the polishing pad, and the fluid source is through the outlet to raise the flattened fiber substantially perpendicular to the surface of the polishing pad. A semiconductor wafer polishing apparatus for polishing a semiconductor wafer provided with a fluid. 2. Consumed polishing material and by-products tend to be embedded in the polishing pad during polishing of a semiconductor wafer, the outlet of the extension pipe from the surface of the polishing pad to the consumed polishing material. 2. The semiconductor wafer polishing apparatus according to claim 1, wherein a gas for blowing off substances and by-products is provided. 3. The semiconductor wafer polish of claim 1, wherein the outlet of the extension pipe is oriented at an angle to the surface of the polishing pad, the angle being about 45 ° in the direction of rotation of the platen. apparatus. 4. The semiconductor wafer polishing apparatus according to claim 1, wherein the extension pipe is pivotally supported on the polishing pad. 5. The semiconductor wafer polishing apparatus according to claim 1, wherein the fluid supply source supplies air at a gauge pressure of about 4.4 atmospheres (about 65 PSIG) through the extension pipe. 6. A step of rotating a polishing pad having a fiber, a step of supporting an extension pipe having an inlet and an outlet with respect to a surface of the polishing pad with a space, and a fluid passing through the inlet. Feeding into the extension pipe and exiting through the outlet, the outlet directing fluid to the polishing pad to raise the flattened fiber substantially perpendicular to the surface of the polishing pad. Method for polishing semiconductor wafers. 7. The method of polishing a semiconductor wafer according to claim 6, wherein the fluid is extruded through a plurality of holes in the outlet of the extension pipe at an angle of about 45 ° in the rotation direction of the polishing pad. 8. A rotatable platen, a polishing pad supported on the platen, and an extension pipe supported with a space with respect to the polishing pad. The surface-treated fibers of the polishing pad have fibers adapted to extend substantially perpendicular to the surface of the polishing pad and be coated with a material that removes debris, the surface-treated fiber of the polishing pad being a material during polishing of a semiconductor wafer. Contacting the surface of the semiconductor wafer for selective removal of the polishing pad, the polishing pad tends to embed spent polishing material and byproducts in the pad, and the fiber contacts the surface of the semiconductor wafer. Tends to lie flat against the surface of the polishing pad during, the extension pipe has an inlet and an outlet, and the inlet is connected to a fluid source. The outlet is directed to the upper surface of the fiber polishing pad, the fluid supply source undergoes substantially vertically fibers flattened against the polishing pad,
And a semiconductor wafer polishing apparatus for polishing a semiconductor wafer having a layer of material on the surface thereof which is provided with fluid through the outlet to blow off polishing material and byproducts from the polishing pad. 9. A polishing pad having a fiber on its top surface, which usually extends substantially perpendicular to the surface of the polishing pad and tends to be flat against the surface during polishing of a semiconductor wafer; A fluid distribution device that is supported in space with respect to the surface of the pad, the fluid distribution device having an inlet and an outlet, the inlet being coupled to a fluid generating means, and the outlet being of the polishing pad. A semiconductor wafer directed to a surface such that the fluid generating means is provided with fluid through the outlet to raise the flattened fibers on the polishing pad substantially perpendicular to the surface of the pad. Semiconductor wafer polishing equipment for polishing wafers. 10. A step of rotating a polishing pad having a fiber, a step of supporting an extension pipe with a space with respect to a surface of the polishing pad, and a fluid being fed into the extension pipe through the inlet. Exiting through an outlet, the outlet being adapted to direct fluid toward the polishing pad to raise the flattened fiber substantially perpendicular to the surface of the polishing pad. Method for polishing a semiconductor wafer for reclaiming a polishing pad having a finished fiber.