JP2002184730A - Semiconductor device processing hard foamed resin grooved pad and pad groove cutting tool - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hard foamed resin grooved pad of high working efficiency and a pad groove cutting tool so as to solve a problem of preventing a hard foamed resin base pad used in a CMP method from deteriorating in working efficiency due to the fact that the opening corners of fine grooves provided on the surface of the above pad are apt to get dull and become hard to control a flow of slurry when the fine grooves provided to the surface of the pad are provided by forming with a die. SOLUTION: A cutting edge is so shaped as to have a tool angle of 15 deg. to 35 deg. and a back clearance angle of 65 deg. to 45 deg., and furthermore it has a side clearance angle of 1 deg. to 3 deg. because its side bears against the peripheral wall of the groove, the back clearance angle of the cutting edge is made wide so as to prevent the cutting edge from interfering with the wall of a small groove, by which various grooves, from small to large ones, of the same shape having a rectangular edge at the corner can be easily cut in a hard urethane foam pad.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a CMP (Chemical Mechanical
The present invention relates to a polishing pad used for ishing) and a tool for processing a groove of a pad. More specifically, the shape and small diameter area of a tool used when a concentric fine ring groove is efficiently processed by turning on a hard foam resin pad. The present invention relates to a hard foamed resin pad in which grooves having a uniform cross-sectional shape are turned from to a large diameter region.

[0002]

2. Description of the Related Art In a semiconductor manufacturing process, for example, various polishing pads are used in a CMP method in which various thin film layers on a silicon wafer surface are chemically mirror-finished. Some of these pads have a composite structure of loosely bonded abrasive grains and resin. During processing, abrasive grains released from the disk due to friction between the wafer surface and the polishing pad act on the wafer surface to form a mirror surface. In this case, the processing efficiency depends on the degree of the abrasive grains to be detached.

In order to easily control the movement of the abrasive grains of the slurry, a pad is made of a hard foam resin having a porous surface in order to produce a pad. The fine particles for processing typified by abrasive grains are appropriately selected depending on the physical properties of the wafer, the shape accuracy and the roughness of the target finished surface, and may be in contact with the wafer and fixed fine particles or in contact with floating fine particles. Is selected. In order to improve the degree of mirror finish of the flattened surface, the latter method is adopted in the CMP method, which is a type of float polishing, and a slurry consisting of fine particles and liquid is constantly supplied between a wafer and a pad in a constant amount. Supply and work.

Some wafers have strong brittle fracture,
Since the wafer has a mechanical weakness that cracks and chips are likely to occur, the wafer thinning step may have to be performed only by lapping or polishing, and the polishing step is an important step. In a mirror polishing machine with the function of a lap grinder, a wafer is fixed on a table and a pad is fixed on the flange end surface at the lower end of the grinding wheel shaft, and a liquid containing abrasive particles is constantly supplied while the table and the grinding wheel shaft are rotating, and mirror finishing is performed. The work efficiency is measured. In the case of a semiconductor device flattening process, a pad is mounted on a circular table.

The slurry supplied constantly is uniformly supplied to the upper surface of the wafer, and does not stay at a certain position on the surface of the wafer, and is renewed with a newly supplied liquid. There is a need. Conventionally used pads are provided with a number of small holes on the surface to ensure the fluidity and uniformity of the liquid flowing between the wafer and the pad, or a group of grooves that are orthogonal or oblique based on straight grooves. And to improve work efficiency. Improvements have been made to the material of the pad as well as the shape of the groove.

In the multilayer wiring technology, the CMP method is often used for flattening each wiring metal layer. Float polishing is indispensable because the wiring metal layer is soft. In particular, the shape of the groove formed in the pad and the size and machine of the polishing cloth are used to efficiently perform the flattening process with slurry and further improve the processing efficiency. Property is important. As a conventional technique, there is a method of forming a large number of grooves at once with a mold from the point of production efficiency.However, the outer diameter of the pad to be formed increases, the number of grooves increases, and the groove shape becomes more uniform as the groove shape becomes finer. It is difficult to do. Fluctuations in the fluidity of the resin, which is a common drawback associated with molding, cause irregularities in the groove shape.

In particular, the surface layer of a wafer or device is made of a soft material, and it is difficult to mirror-finish or flatten the surface layer with a conventional pad surface shape to achieve a predetermined mirror surface quality. In addition, it is necessary to carry out trials to suppress the occurrence of the hydroplane phenomenon between the pad surface and the surface to be processed due to the shape of the groove on the pad, etc. Manufacturing is essential.

[0008]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems of the prior art, and has as its object to provide a slurry for efficiently mirror-finishing a semiconductor wafer or a device surface. Hardness for semiconductor wafer processing that has concentric fine grooves that can ensure smooth flow of slurry without applying excessive processing pressure to the surface to be polished in consideration of fluidity and characteristics of the metal to be machined An object of the present invention is to provide a foamed resin grooved pad and a tool for turning grooves.

[0009]

According to a first aspect of the present invention, there is provided a pad for processing a semiconductor device, wherein the base material of the pad is a hard foamed resin material, and the pad has a groove width of 0.1 mm.
1 mm to 0.3 mm, groove depth 0.1 mm to 1.0
mm groove, the groove pitch is 0.2 mm to 2.0 mm,
At least 20mm to 200mm in diameter with a large number of strips formed concentrically, and a groove having an edge perpendicular to the corner portion is formed by turning from the small diameter groove at the center of the pad to the groove closest to the outermost diameter in the same shape. It is.

According to the present invention, by turning the surface groove of the hard foamed resin pad, the wall of the groove can be formed at right angles to the upper surface of the pad, and the groove can be formed uniformly, so that the slurry is concentric. It moves appropriately in the gap between the groove and the pad and the device, and the slurry is constantly updated, so that the processing efficiency can be improved. By forming the groove of the pad with a fine groove width, the acting force at the time of slurry flowing to the pad surface is adjusted, which is effective in suppressing the hydroplane phenomenon and flattening.

According to a second aspect of the present invention, the shape of the cutting edge is set at a blade angle of 15 to 35 degrees, a front clearance angle of 65 to 45 degrees,
The lateral relief angle of the cutting blade abutting on the outer peripheral side wall of the groove is formed in the range of 1 to 3 degrees, and in order to avoid interference with the groove wall in the small diameter groove, the front relief angle is made large and a right angle to the corner portion. A groove having a sharp edge from a small-diameter groove of the pad to a groove close to the outermost diameter of the pad is easily formed into a hard urethane foam pad by turning into the same shape.

According to the second aspect of the present invention, the semiconductor device processing pad has a diameter of at least 20 mm to 200 m.
In order to form a large number of grooves of concentric circle width by turning, the cutting edge shape is set to a front relief angle of 65 to 45 degrees, a side clearance angle corresponding to a tool angle of 15 to 35 degrees. Is formed at 1 ° to 3 ° and the front clearance angle is specified at 65 ° to 45 ° so as to avoid interference with the outer-diameter-side groove wall in the small-diameter groove so that the edge of the groove corner can be held at a right angle. It prevents the occurrence of drooling and scorching on the wall.

According to a third aspect of the present invention, a single cutting blade is arranged and projected on the same side surface of a plate-like tool to form a multi-blade unit, and the multi-blade unit is fixed to a unit holder so as to be replaceable. One or more of the multi-blade unit tools are arranged so that the groove pitches are aligned and are replaceable, and concentric multiple grooves are simultaneously formed by turning.

According to the third aspect of the present invention, there is provided a multi-blade tool for efficiently providing a groove having a fine groove width to a pad by turning.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to the drawings, a CMP processing pad manufactured using a turning tool according to the present invention.

As the base material of the pad used in the CMP process, hard foamed resin is frequently used from the viewpoint of cost and stability of physical properties. Especially elastic deformation characteristics, thermal conductivity, durability,
Pads based on rigid urethane foam sheets are often used at present, judging comprehensively from the viewpoints of productivity and economic efficiency. However, rigid urethane foam sheets are generally unsuitable for cutting because of their mechanical properties, and the grooves on the sheet surface required when used as pads are:
A method of forming the grooves at the same time as molding with a mold having a groove has been sought because it is an efficient production method.

The outer diameter of the pad and the number of grooves have been increased, and pads having finer groove widths have recently been demanded in the CMP method. In molding with a mold, the corner portion at the groove entrance is easily dripped, and it is difficult to control the fluidity of the slurry. Therefore, it has been necessary to form a groove having an edge perpendicular to the corner portion by cutting. The invention of the present application makes it possible to specify a cutting edge suitable for turning of a hard foamed resin material, and to provide a pad for CMP processing in which a groove with little peeling or swelling or inclination of the wall is provided by turning on the wall surface of the groove. Is what you do.

FIG. 1 shows a groove 3 formed in a pad substrate 2 with a single cutting blade 1.
Shows a state in which is turned. Here, it is required that the groove wall surface 3a be uniformly turned. FIG. 2 shows that when the outer shape and the groove of the pad are simultaneously formed by the mold, the inclination 2a and the swelling 2b of the wall surface occur. Next, it is necessary to provide a uniform groove as far as possible from the center portion to the position closest to the outer diameter of the pad used for the CMP process. Actual minimum diameter is around 20mm but maximum diameter is 250mm
There is a possibility that a pad of about 1000 mm will be required in the near future, increasing from 500 mm to 500 mm. When turning a ring groove having a large diameter, the amount of interference between the processed groove and the cutting edge is small, but the smaller the groove diameter, the greater the amount of interference.

However, at present or in the near future, the maximum diameter of the pad is required to be in the range of 500 mm to 800 mm. In this case, the grooves from the minimum diameter area to the maximum diameter area are formed by turning with the same tool with high productivity. The point is that a uniform groove can be provided to the pad. The present invention solves this problem by using a multi-edge turning tool according to the present invention described later and provides a grooved pad that can be used for CMP processing.

FIG. 3 is a partial view of the grooved pad, and shows that the groove 3 is formed with a large number of grooves uniformly except for a part of the central portion. FIG. 4 is a sectional view taken along the line AA of FIG. 3 and shows a uniform groove formed. The grooves are uniformly processed on the pad surface.In addition, to control the fluidity of the slurry and to suppress the hydroplane phenomenon caused by the slurry, the groove pitch is changed at a fixed cycle or the groove pitch is adjusted in consideration of the viscosity of the slurry. It may be irregular.

FIG. 5, FIG. 6, and FIG. 7 show a pad for CMP processing using a hard urethane foam sheet as the pad base material. 7 shows a pad in which a groove group having the groove shape and the groove pitch shown in FIG. 5 or 6 is uniformly formed by turning from a minimum diameter of 20 mm to a position close to the outermost diameter of the base material.

The shape of the groove to be turned on the pad is as follows. The groove width is specified in a range of 0.1 mm to 1.0 mm. This is because the fluidity of the slurry is controlled, and the supply of the abrasive grains and the discharge of the processing chips or the reaction products are influenced by the unevenness of the foam surface and the size of the groove width. Groove width is 0.1m
When the groove width is smaller than m, the controllability of the slurry and the machinability due to the turning of the groove are reduced, so there is a limit. As it gets worse, there are limits.

A factor in selecting the groove width is the hardness of the pad material. For materials with low hardness, the groove width x groove depth is set to 0.
In the case of a pad base material having a relatively high hardness of 2 mm × 0.2 mm, a groove pitch that can be selected to be 0.4 mm × 0.8 mm is specified in a range of 0.2 mm to 2.0 mm. The specification of the groove pitch is selected according to the degree of mirror finish and the processing efficiency of the flattening process of a soft wiring member such as copper or gold of a semiconductor device. Usually, the groove pitch is often specified in the range of 1 mm to 2 mm. If the groove pitch is made smaller than necessary, it is difficult to suppress the hydroplane phenomenon in relation to the viscosity of the slurry, so it is necessary to specify it carefully. As specific values, groove width x groove depth x groove pitch is 0.3 mm x 0.4 mm x
There is 2 mm. As the diameter of the turning groove of the pad becomes smaller, the problem of interference between the cutting edge of the turning cutting edge and the outer diameter of the groove and the cutting speed decrease, so that the machinability of the groove deteriorates. In particular, for groove turning with a diameter in the range of 20 mm to 200 mm, it is necessary to specify the cutting edge shape.

For turning grooves on the pad used in the CMP method using hard foamed urethane as a base material described in Example 1, the blade angles of 15, 20 and 25 degrees are specified and the corresponding clearance angle is 45 degrees. , The lateral clearance angle is specified as 3 degrees. The selection of the blade angle is made in consideration of the physical properties of the machinability and the exclusion of cutting chips due to the work material and the like. The blade width of the cutting blade is determined so that the groove shape after turning has a predetermined dimension. As a specific example of the blade width and the groove pitch, the blade width × the groove pitch is 0.25 mm × 1.1 m
The pad surface is formed by turning with a specific size of m or 0.3 mm × 2.0 mm.

The effect of the cutting edge shape of the tool on the machining quality of the groove when machining the pad with the turning groove tool specified in the present invention will be described below. FIG. 8 shows an explanation of the terms of the cutting edge portion. In particular, among the resins, foamed resin materials containing pores are often not subjected to cutting with a cutting tool. Therefore, a molded product of a hard urethane foam pad, which is a hard foam resin that is a base material of the pad for the CMP process, has been conceived as a method with high productivity. However, recent CM
Due to the demands on the P method processing, a fine groove width is required, and the conventional pad manufacturing method has limitations in response to the increase in pad shape, and cutting is considered to be dauntingly low in productivity to overcome this. It is under consideration that a method by processing must be selected, and studies have begun.

Turning to a multi-blade tool is most likely to be considered as a means of productivity that is almost comparable in terms of productivity as compared with the manufacturing method by molding. Therefore, the first problem is to specify the shape of a single cutting edge for processing a uniform groove in a rigid urethane foam sheet. Second
As a problem of the CMP processing pad, it is necessary to uniformly turn a groove of the same shape from the small diameter groove at the center of the pad to the groove closest to the outermost diameter. The interference with the side surface of the cutting blade in contact is particularly remarkable, causing the wall to be cut off or drooped. Therefore, it is necessary to give special consideration to the shape of the cutting edge in order to machine the groove from the inner diameter portion to the outer diameter portion with a tool having the same shape.

Therefore, the shape of a single cutting edge, which is the first problem, is specified as a blade angle of 15 to 35 degrees, and correspondingly, a front clearance angle of 45 to 65 degrees. The angle range is determined by the relationship with the work material. As the work material is softer, the blade angle is closer to 15 degrees and the front clearance angle is closer to 45 degrees. In addition, the shape of the single cutting edge is finally determined by determining the machinability by keeping the blade angle constant and increasing the front clearance angle from 45 degrees. The width of the single cutting blade is selected from a range of 0.1 mm to 1.5 mm, which is suitable for turning the groove on the pad to be finally formed in a width of 0.1 mm to 1.0 mm.

Hard urethane foam is similar to wood cutting, and it is desirable that the cutting edge is sharp and the cutting edge is shaped to abut on the workpiece from both sides to start cutting. For example, when the tool is polished, the cutting edge is polished so that the center portion of the cutting edge becomes concave and the cutting edge is formed in an arc so that both ends of the cutting edge protrude. Also, instead of making the cutting edge straight, leave a grinding mark only at the tip of the cutting edge and leave a minute sawtooth.The rake face, front flank face and blade side face should be polished so that chips etc. can flow, or should be extremely smooth. is necessary.

Next, the second problem will be described. Consider the conditions that must be met when machining from the minimum diameter to the maximum diameter of a groove with a single cutting edge of the same shape. In order to avoid interference with the groove wall in the small diameter groove, the front clearance angle may be increased. Thus, Table 1 shows the results of trial calculations at front clearance angles of 10, 45, and 80 degrees assuming that the diameter of the small diameter portion is 20 mm and the groove depth is 1.0 mm.

[0030]

[Table 1]

The calculation formula of the numerical value to be displayed is as follows.
Assuming that the front clearance angle is 10 degrees, the groove diameter is 20 mm, and the groove depth is 1 mm, the position where the outer edge of the front clearance surface contacts the surface of the pad can be obtained by the following equation.

(Equation 1) Therefore, the amount of interference is 11.496-10 = 1.496.

When the front clearance angle is set to 45 degrees, the interference amount becomes 0.05 mm, and it is understood that no interference occurs when the lateral clearance angle is set to about 3 degrees. From this point, a single cutting edge is selected with a front clearance angle of about 45 degrees and a small blade angle and a large rake angle. FIG. 9 is an explanatory diagram of the procedure for calculating the amount of interference. The material of the tool may be carbon steel, alloy steel, high-speed steel, cemented carbide, cermet, stellite, or ultra-high pressure sintered body. In order to increase the cleanliness of the pad, ceramic can be used to prevent rust from entering. Average cutting condition is 200m / mi peripheral speed
n, the feed is set to 0.05 or less. Although the cutting speed can be controlled to be constant, there is almost no difference in finish. The blade width of the cutting edge during hard foam resin turning is determined in consideration of the physical properties of the material so that the groove shape after the turning has a predetermined dimension depending on the material.

In the present invention, a plurality of cutting blades having the same shape are cut into the pad using a multi-blade tool, and the grooves are simultaneously turned by a predetermined number of cutting blades. Therefore, a fixed number of cutting blades are formed on one chip to form a unit, thereby improving the machining efficiency of the groove and facilitating the production and maintenance management of the tool.

FIGS. 10 and 11 show a first embodiment of a multi-blade tool.
Shown in A single cutting blade 1 is formed at a predetermined pitch on the same side surface of a plate-like tool tip to form a multi-blade unit 4, which is fitted to a positioning pin 6 fixedly mounted on a unit holder 5 and positioned, and a holding plate 7. The multi-blade unit tool is clamped and fixed with bolts 8. One or more of the multi-blade unit tools are arranged so that the groove pitch is the same, and are fixed to a tool base.
It is possible to efficiently process a large number of grooves by controlling the axis NC (FIG. 12). FIG. 13 shows an example of the multi-unit holder 9 in which a number of multi-blade units are assembled on one holder. As shown in FIG. It is easy to secure the pitch between the blades, and the convenience in operation is obtained.

[0035]

According to the first aspect of the present invention, by manufacturing a pad for CMP processing by turning, even if the groove width is delicate, the wall and the upper surface of the groove can maintain the perpendicularity, so that the gap between the device processing surface and the pad upper surface can be maintained. The flow of the slurry can be easily controlled, and the occurrence of the hydroplane phenomenon between the two can be suppressed, so that the soft metal surface of the device can be efficiently planarized by CMP.

According to the second aspect of the present invention, by specifying the shape of the cutting edge, the edge of the groove corner outside the small diameter groove is made a right angle,
The turning groove can be machined to prevent the wall from drooling and peeling.

According to a third aspect of the present invention, a turning multi-blade tool having a single cutting edge as a constituent element is modularized and configured so that a large number of turning grooves can be processed with high efficiency.

[Brief description of the drawings]

FIG. 1 shows a groove processing diagram with a single cutting edge, showing a preferable groove wall surface.

FIG. 2 is a diagram showing a groove shape formed by using a mold, in which a wall surface of the groove is inclined or swollen.

FIG. 3 is an enlarged view of a surface and a groove of a grooved pad. Although the figures show uniform grooves, irregular pitches can be used.

FIG. 4 is a sectional view of the groove in FIG. 3;

FIG. 5 is a cross-sectional view of a rigid urethane foam pad for CMP processing.

6 is a cross-sectional view of a pad having a finer groove width than the pad of FIG.

FIG. 7 is a view showing a state in which the grooves shown in FIG. 5 or FIG.

FIG. 8 is an explanatory diagram of terms of a cutting edge portion.

FIG. 9 is an explanatory diagram of a calculation procedure of an interference amount between a front flank and a work surface.

FIG. 10 is an explanatory view of processing a multi-slot groove by a multi-blade unit having cutting edges formed at a pitch twice the groove pitch.

FIG. 11 is an overall view of a multi-blade unit tool.

FIG. 12 is an explanatory view showing that a multi-blade unit tool is juxtaposed to simultaneously machine a large number of grooves.

FIG. 13 is an external view in which a multi-blade unit is arranged in a multi-unit holder.

[Explanation of symbols]

 Reference Signs List 1 cutting blade 2 pad base material 3 groove 4 multi-blade unit 5 unit holder 6 positioning pin 7 holding plate 8 bolt 9 groove cutting tool 10 tool holder

Claims (3)

[Claims] 1. A pad for processing a semiconductor device, wherein a base material of the pad is a hard foamed resin material, and the pad has a groove width of 0.1 mm to 0.3 mm and a groove depth of 0.1 m.
m to 1.0 mm grooves, the groove pitch is 0.2 mm to 2.0 mm, at least 20 mm to 200 mm in diameter
Between the small diameter groove at the center of the pad and the groove closest to the outermost diameter are formed by turning the grooves having edges perpendicular to the corners in the same shape. Pad with foam resin groove. 2. The shape of the cutting blade is set at a blade angle of 15 to 35 degrees,
The front relief angle is 65 ° to 45 °, and the lateral relief angle of the cutting blade abutting on the outer peripheral side wall of the groove is in the range of 1 ° to 3 °. In order to avoid interference with the groove wall in the small diameter groove, the front relief angle is set. The groove has a large angle and a groove with a right-angled edge at the corner part.The groove from the small-diameter groove of the pad to the groove closest to the outermost diameter is turned into the same shape by turning, making it easy to form the groove on the hard urethane foam pad. Turning groove machining tool. 3. A multi-blade unit tool, wherein a single cutting blade is aligned and protruded on the same side surface of the plate-shaped tool to form a multi-blade unit, and the multi-blade unit is replaceably fixed to a unit holder to form a multi-blade unit tool. Turning grooves for hard foam resin pads, characterized in that one or more multi-blade unit tools are arranged so that the groove pitch is aligned and are replaceable, and concentric multi-slots are formed simultaneously by turning. Tools.