KR101292224B1 - Apparatus and method for dressing pad for polishing wafer - Google Patents

Abstract

According to the embodiment, the wafer polishing pad cutting device for cutting the upper polishing pad and the lower polishing pad for polishing the wafer interposed therebetween, cutting more edges than the center portion of the upper polishing pad and the lower polishing pad facing each other, And at least one cutting member such that the edges of the cut upper and lower polishing pads have a larger gap than the center portion.

Description

Apparatus and method for dressing pad for polishing wafer

Embodiments relate to a wafer polishing pad cutting apparatus and method.

Single crystal silicon wafers, which are raw materials for manufacturing semiconductor devices, etc., are largely manufactured through a shaping process, a polishing process, and a cleaning process, and further selectively perform a process of growing an epitaxial layer. Can be.

The shaping process is a slicing process that cuts ingot-shaped single crystals into wafer form, a lapping process that mechanically polishes the wafer to control the thickness and removes defects caused by the slicing process. The etching process can be subdivided into an etching process for chemically removing a defect due to, and a grinding process for removing a defect due to the etching process.

In addition, the wafer polishing process includes a double side polishing (DSP) process that removes surface defects caused by the shaping process and improves the flatness of the wafer by polishing a wafer thickness of about 10 to 20 μm, and about 1 It can be divided into a final polishing process in which mirroring is performed by finely polishing a thickness of about 占 퐉 and improving roughness.

The above-described polishing process ensures polishing flatness of the wafer by using a polishing pad and an abrasive. At this time, the material polished from the wafer and the particles in the abrasive are bonded to each other to penetrate into the polishing pad impregnation structure to advance vitrification of the polishing pad. As such, the speed of polishing the wafer is reduced by vitrification at a certain portion of the polishing pad, and the nonuniformity of the surface of the polishing pad is caused, thereby deteriorating the flatness of the surface of the wafer polished by the polishing pad.

In order to remove such vitrification of the polishing pad, a method of dressing the polishing pad is applied in the polishing process. The polishing pad dressing method includes a method of scraping (or cutting) the surface of the polishing pad with a brush or diamond paper.

1A and 1B are graphs showing flatness quality levels according to a general surface gap, SBIR is a Site Back Ideal focal plane range, and SFQR is an index of flatness as a reference plane-site front least square focal plane range.

In general, when evaluating the actual processing of a DSP device in a line, as shown in Figs. 1A and 1B, there is a difference in the quality level between Group A below a certain gap and Group B above a certain gap, according to the difference in the surface gap. Appears clearly.

2 (a) to 2 (c) show the test results for making the gap difference of the surface plate, FIG. 2 (a) shows the condition, FIG. 2 (b) shows the expected effect, and FIG. 2 (c) shows The test results are shown.

Within the process, a method that can change the surface gap difference as described above is a diamond dresser. The test result to make the gap difference of the surface is as shown in Figure 2 (c). As a result of confirming the pad profile according to the relative speed by changing the recipe of the dresser under the conditions shown in FIG. 2 (a), unlike the expected effect on the pad profile shown in FIG. 2 (b), FIG. 2 (c) As shown in FIG. 2, the two profiles (TEST1, TEST2) showed no significant change in the profile of the pad, and the quality level did not show a large tendency compared to the reference value (Ref). It can be seen that the pad profile control using the relative speed is difficult. Since the circular diamond dresser being applied to the process is dressing over the front of the pad, partial control of the sun gear section and the internal gear section is difficult.

3 is a diagram illustrating a general pad profile change, and is composed of an upper plate 10, a lower plate 20, an internal gear unit 30, and a sun gear unit 40.

Referring to Figure 3, there is a difference in the quality level according to the occurrence of the difference between the gap 50 of the upper plate 10 and the lower plate 20 in the DSP device, the shape of the plate 10, 20 It takes a lot of time and money to replace them all or rework them.

In addition, in the pad profile control using a diamond dresser, there is a limit in controlling the radius reference plate gap, so it is urgently necessary to secure the plate gap level to be changed at a minimum cost.

Embodiments provide a wafer polishing pad cutting apparatus and method that enables a minimum cost change of the profile of the pad so that the surface gap has a constant level, thereby improving and controlling the quality and flatness of the wafer edge.

According to an embodiment, a wafer polishing pad cutting device for cutting an upper polishing pad and a lower polishing pad for polishing a wafer interposed therebetween cuts more edges than a center portion of the upper polishing pad and the lower polishing pad facing each other. And at least one cutting member such that edges of the cut upper polishing pad and the lower polishing pad have a larger gap than the central portion. At this time, the cutting member may have a cutting surface that increases in the shape of a fan or trapezoidal toward the edge from the central portion.

Further, the cutting device cuts the upper polishing pad so that the cutting amount of the upper polishing pad linearly increases from the center portion to the edge. Alternatively, the lower polishing pad may be cut so that the cutting amount of the lower polishing pad increases linearly from the center portion to the edge. Alternatively, the upper and lower polishing pads may be cut such that the cutting amounts of the upper and lower polishing pads linearly increase from the center portion to the edges.

Further, the edge of the upper polishing pad is cut more than the edge of the lower polishing pad. Alternatively, the edge of the lower polishing pad is cut more than the edge of the upper polishing pad.

According to another embodiment, a wafer polishing pad cutting device for cutting an upper polishing pad and a lower polishing pad for polishing a wafer interposed therebetween further includes a center portion more than an edge of the upper polishing pad and the lower polishing pad facing each other. It may include a cutting member to cut a lot, to increase the curvature at the edge of the wafer.

In addition, a wafer polishing pad cutting method for cutting an upper polishing pad and a lower polishing pad for polishing a wafer interposed therebetween includes cutting more edges than a center portion of the upper polishing pad and the lower polishing pad facing each other, Edges of the cut upper polishing pad and the lower polishing pad may have a larger gap than the center portion.

In the wafer polishing pad cutting apparatus and method according to the embodiment, there is a clear difference in the quality level according to the gap difference between the upper and lower plates, and the upper polishing pad and the upper polishing pad are controlled by controlling the pad profile rather than the surface shape. Since the gap between the lower polishing pads is secured within a certain range, it is possible to improve the quality of the wafer by securing the surface gap level to be changed at a minimum cost without the need to replace or rework the surface.

1A and 1B are graphs showing the level of flatness quality according to the gap of a general surface plate.
2 (a) to 2 (c) show test results for making gap difference of the surface plate.
3 is a diagram illustrating a general pad profile change.
4 is a partial cutaway perspective view of a typical wafer double-side polishing apparatus.
5A and 5B are views illustrating profile changes of upper and lower polishing pads after cutting the upper and lower polishing pads according to an embodiment.
6A and 6B show a plan view and a rear view of a cutting member of the wafer polishing pad cutting device according to the embodiment.
7 is a plan view of a cutting member according to an embodiment.
8A and 8B are views showing a change profile associated with an increase in the amount of cutting of the pad on the sun gear side according to the embodiment.
9 is a graph showing the relationship between gap and wafer edge stress.
10 is a view for explaining the cutting amount and the operation of the cutting member having a shape according to the embodiment.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings in order to facilitate understanding of the present invention. However, the embodiments according to the present invention can be modified into various other forms, and the scope of the present invention should not be construed as being limited to the embodiments described below. Embodiments of the invention are provided to more fully describe the present invention to those skilled in the art.

4 is a partial cutaway perspective view of a typical wafer double-side polishing apparatus.

Referring to FIG. 4, the carrier 210 is mounted on the wafer double-side polishing apparatus 200 and used. The wafer double-side polishing apparatus 200 is installed so that the upper polishing pad 232 is attached to the lower surface of the upper surface plate 202 and the upper surface plate 202, and the lower surface surface plate 204 has the lower polishing pad 234 attached to the upper surface. ), A line which is installed at the outer periphery of the lower plate 204 and rotates in the opposite direction to the internal gear unit 240 that is installed at the center of the upper gear plate 240 and the upper plate 202. It is provided with a sun gear unit 220 and a carrier 210 installed between the upper plate 202 and the lower plate 204 and rotated by the sun gear unit 220 and the internal gear unit 240. do.

A nozzle (not shown) is provided above the upper plate 202, and an inlet through which the polishing liquid 260 supplied through the nozzle flows into the lower plate 204. Is formed. That is, the polishing liquid such as slurry 260 is supplied through the inlet when polishing the wafer 250.

The wafer 250 is seated on the carrier 210 provided between the upper plate 202 and the lower plate 204, and the wafer 250 is attached to the upper plate 202 and the lower plate 204, respectively. It is interposed between the polishing and lower polishing pads 232 and 234 and is rubbed and polished with the pads 232 and 234. As such, the wafer 250 is rubbed and polished as the upper polishing pad 232 and the lower polishing pad 234 rotate in opposite directions.

The gear portion formed on the outer circumferential surface of the sun gear portion 220 and the gear portion formed on the inner surface of the internal gear portion 240 are meshed with the gear 212 formed on the outer circumferential surface of the carrier 210. Thus, as the upper plate 202 and the lower plate 204 are rotated by a driving source (not shown), the carrier 210 rotates and revolves.

The carrier 210 supports the wafer 250 polished by the upper plate 202 and the lower plate 204, and flattens the upper and lower polishing pads 232 and 234 to polish the wafer 250. It serves to maintain.

Hereinafter, an apparatus and method for cutting a wafer polishing pad according to an embodiment will be described with reference to the accompanying drawings.

5A and 5B are views illustrating profile changes of the upper polishing pad 232 and the lower polishing pad 234 after cutting the upper and lower polishing pads 232 and 234 according to the embodiment.

The wafer polishing pad cutting device according to the embodiment cuts more edges than a center portion of at least one of the upper polishing pad 232 and the lower polishing pad 234 facing each other. Accordingly, when compared with the general upper and lower polishing pads 10 and 20 shown in FIG. 3, the upper and lower polishing pads 232 and 234 cut into the wafer polishing pad cutting device according to the embodiment are illustrated in FIG. 5A or 5B. As shown in FIG. 2, the gap d2 at the edge may be larger than the gap d1 at the center portion, so that a gap between the upper and lower polishing pads 232 and 234 may be uniformly maintained.

That is, the edges of the upper and lower polishing pads 232 and 234 are cut more than the center portion of the upper and lower polishing pads 232 and 234, so that the upper and lower polishing pads (as shown in FIG. 232 and 234 have an appropriate curvature. As a result, the gap d2 at the edges of the upper polishing pad 232 and the lower polishing pad 234 may have a predetermined value or more.

According to an embodiment, the gap d2 at the edge of the upper polishing pad 232 and the lower polishing pad 234 is larger than the gap d1 at the center of the upper and lower polishing pads 232 and 234. In comparison with the upper polishing pad 10 shown in FIG. 3, the edge of the upper polishing pad 232 shown in FIG. 5A may be cut more than the edge of the lower polishing pad 234.

According to another embodiment, the gap d2 at the edge of the upper polishing pad 232 and the lower polishing pad 234 is larger than the gap d1 at the center of the upper and lower polishing pads 232, 234. For example, the edge of the lower polishing pad 234 shown in FIG. 5B may be cut more than the edge of the upper polishing pad 232 as compared to the lower polishing pad 20 shown in FIG. 3.

6A and 6B show a plan view and a rear view of the cutting member 403 of the wafer polishing pad cutting device according to the embodiment. That is, FIG. 6A shows the front side of the cutting member 403 abutting for cutting the upper and lower polishing pads 232, 234, and FIG. 6B shows the upper and lower polishing pads 232, 234 not touching. The back side of the cutting member 403 is shown.

7 shows a top view of a cutting member 403 according to an embodiment.

As shown in FIGS. 6A, 6B, and 7, the cutting member 403 has a plurality of portions A, B, and C, and the cutting area of the cutting member 403 is edged from the center portion A. FIG. As you go to (C), it may increase in the shape of a fan or trapezoid. For example, the wafer polishing pad cutting apparatus according to the embodiment is shown in FIG. 5A so that the cutting amount of the upper polishing pad 232 increases linearly from the center portion A shown in FIG. 7 to the edge C. FIG. As shown, the upper polishing pad 232 may be cut.

Alternatively, the wafer polishing pad cutting device may have a lower polishing pad as shown in FIG. 6B such that the cutting amount of the lower polishing pad 234 increases linearly from the center portion A shown in FIG. 7 to the edge C. FIG. 234 can be cut.

Alternatively, the wafer polishing pad cutting device includes the upper and lower polishing pads 232 and 234 so that the cutting amount of the upper and lower polishing pads 232 and 234 increases linearly from the center portion A to the edge C. You can also cut all of them.

That is, the cutting amount of at least one of the upper and lower polishing pads 232 and 234 described above may increase linearly as shown in Equation 1 below.

Here, Q _A , Q _B , and Q _C represent the amounts of the pad being cut by the respective portions A, B, and C of the cutting member 403 shown in FIG. 7.

As described above, in at least one of the upper and lower abrasive members 232 and 234, the internal gear portion 240 side C can be cut relatively more than the sun gear portion 220 side A. The cutting member 403 has a fan or trapezoidal shape. Therefore, since more cutting effect is given to the inner gear portion 240 side C, the gap d2 between the edges of the upper and lower polishing pads 232 and 234 as shown in FIG. 5A or 5B. ) Can be maintained above a certain level.

Therefore, according to the embodiment, only the cut shape of the pads 232 and 234 can be changed similarly to the shape gaps of the surface plates 202 and 204 showing good quality levels, thereby improving the distribution of flatness quality. .

8A and 8B are diagrams illustrating a change profile associated with an increase in the amount of cutting of the pads 232 and 234 toward the sun gear unit 220 according to an embodiment.

According to an embodiment, the wafer polishing pad cutting device may cut more center portions than edges of at least one of the upper polishing pad 232 and the lower polishing pad 234 facing each other. In this case, as shown in FIG. 8B, the curvature at the edge 300 of the wafer 250 may be increased. That is, referring to FIG. 8B, the flatness of the edge of the wafer 250 is controlled to maximize the edge drop 300 of the wafer 250, thereby improving ZDD (Z height Double Derivative) quality. Able to know. Here, ZDD is defined as the height of the wafer surface at radial distances.

That is, by increasing the cutting amount of the pad (232, 234) located on the side (A) of the sun gear unit 220, by increasing the processing stress in the internal gear unit 240, the edge portion 300 of the wafer 250 The curvature of can be increased, so that an edge drop such as silicon on insulator (SOI) can be advantageously applied to advantageous wafer shape control.

9 is a graph showing a relationship between a gap and wafer edge stress. Here, reference numeral 320 denotes a friction applied to the wafer edge, and indicates a minimum threshold point of friction between the sun gear unit 220 and the internal gear unit 240.

The surface gap causes a change in the stress 310 at the internal gear portion 240 and the stress 312 at the sun gear portion 220 which affects only the wafer edge. The change in stress 310 in the gear portion 240 is greater.

According to the wafer polishing pad cutting apparatus and method according to the embodiment, the pads 232 and 234 are cut by using the cutting member 403 to ensure a constant gap between the pads 232 and 234 within a specific range. Provide good edge quality of the wafer and allow control of the wafer edge.

10 is a view for explaining the cutting amount and the operation of the cutting member 403 having a shape according to the embodiment.

In the case of the conventional diamond dresser, due to the ratio of the relative relative speeds of the internal gear unit 30 and the sun gear unit 40, the wafer loaded on the carrier between the top plate 10 and the bottom plate 20 is idle and idle. Rotation proceeded simultaneously.

However, the cutting member 403 according to the present embodiment advances only the revolution in the direction of the arrows 332 and 334 between the upper plate 202 and the lower plate 204.

In the case of the embodiment, since the cutting member 403 has the shape of a fan or trapezoid, the internal gear portion 240 of the pads 232, 234 when the pads 232, 234 rotate in the direction of the arrows 330, 334. ) May be cut more than the sun gear 220 side.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, but, on the contrary, It will be understood that various modifications and applications are possible. For example, each component specifically shown in the embodiments can be modified and implemented. It is to be understood that all changes and modifications that come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

10, 202: upper plate 20, 204: lower plate
30, 240: internal gear 40, 220: sun gear
210: carrier 250: wafer
403: cutting member

Claims (9)

A wafer polishing pad cutting device for cutting an upper polishing pad and a lower polishing pad for polishing a wafer interposed therebetween,
At least one cutting to cut more edges than the center portions of the upper polishing pad and the lower polishing pad facing each other so that edges of the cut upper polishing pad and the lower polishing pad have a larger gap than the center portion A wafer polishing pad cutting device comprising a member. The method of claim 1, wherein the cutting member
Wafer polishing pad cutting device having a cutting surface that increases in the shape of a fan or trapezoidal toward the edge from the center portion. The apparatus of claim 1, wherein the upper polishing pad is cut such that the cutting amount of the upper polishing pad increases linearly from the center portion to the edge. The apparatus of claim 1, wherein the lower polishing pad is cut so that the cutting amount of the lower polishing pad increases linearly from the center portion to the edge thereof. The apparatus of claim 1, wherein the upper and lower polishing pads are cut such that the cutting amounts of the upper and lower polishing pads linearly increase from the center portion to the edges. The apparatus of claim 1, wherein the edge of the upper polishing pad is cut further than the edge of the lower polishing pad. The apparatus of claim 1, wherein the edge of the lower polishing pad is cut more than the edge of the upper polishing pad. A wafer polishing pad cutting device for cutting an upper polishing pad and a lower polishing pad for polishing a wafer interposed therebetween,
And a cutting member for cutting more center portions than edges of the upper polishing pad and the lower polishing pad facing each other, thereby increasing curvature at the edge of the wafer. A wafer polishing pad cutting method for cutting an upper polishing pad and a lower polishing pad for polishing a wafer interposed therebetween,
Cutting a wafer polishing pad such that edges of the cut upper polishing pad and the lower polishing pad have a larger gap than the center portion by cutting more edges than the center portions of the upper polishing pad and the lower polishing pad facing each other. Way.

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