JP2003305644A - Dresser for cmp work - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve holding power of abrasive grains and a discharging property of cutting chips while maintaining a cutting rate and working precision equal to or more than that of a conventional dresser, a dresser to dress a polishing cloth to be used for surface finish of a semiconductor wafer by CMP work. <P>SOLUTION: Longevity of the dresser is improved as a discharging effect of slurry and the cutting chips is improved and abrasion and falling of it by concentrative contact pressure to the abrasive grains on the outer peripheral side easiest to receive a load by concentrically forming a plurality of rows of protruded lines 13a-13e on an outer peripheral part 12 of a side surface of a disc type base metal 11, forming height of the protruded line 13a out of these protruded lines 13a-13e lower than height of the protruded line 13c on an intermediate part and fastening one layer of the abrasive grains 14a-14e on an upper surface of these protruded lines 13a-13e by brazing. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dresser for CMP processing suitable for dressing a polisher used for flattening a semiconductor LSI device.

[0002]

2. Description of the Related Art Polishing, which is performed for ultra-precision and high-quality finishing of electronic parts and optical parts, is carried out by spraying soft abrasive grains on a polishing cloth of a polisher and pressing a work piece. Material is removed by chemical or mechanical action between the grain and the work piece. Recently, CMP (C
chemical & Mechanical Poli
A technique called "shing" has attracted attention. An example of this CMP processing device is Japanese Patent Laid-Open No. 7-2971.
There are devices described in Japanese Patent Publication No. 95 and Japanese Patent Application Laid-Open No. 9-111117.

When polishing a semiconductor wafer with such a CMP processing apparatus, a polishing cloth made of polyurethane having a constant elastic modulus, fiber shape and shape pattern is used as a polisher. Polishing is the final step of machining, flatness around 1 μm, surface roughness R _Z
The 10Å level must be achieved.

In such a polishing process, it is necessary to periodically modify the surface of the polishing cloth in order to maintain stable processing performance, and the surface of the polishing cloth is periodically or simultaneously modified by CMP processing using a dresser. The deteriorated layer is removed and an appropriate surface condition is obtained. As this dresser, a dresser in which diamond abrasive grains or the like are fixed to a base material is used.

This method of fixing the abrasive grains to the base metal of the dresser includes fixing by brazing, fixing by electrodeposition, and fixing by an inorganic binder, each of which has its advantages and disadvantages. Here, in terms of dresser scraping rate, in the case of fixing by electrodeposition and fixing by an inorganic binder,
Since the amount of protrusion of the abrasive grains is small and the scraping rate is inferior to the case of fixing by brazing, a dresser in which the abrasive particles are fixed by brazing is advantageous when the scraping rate is important.

FIG. 5A is a cross-sectional view showing a wheel type dresser as an example of a conventional dresser. The outer peripheral portion 41a of the side surface of the disc-shaped base metal 41 is raised to a higher level, and the diamond is formed on the outer peripheral portion 41a. The dresser 40 is formed with an abrasive grain layer 42 having abrasive grains adhered thereto. The dresser 40 is held by a holder 43 as shown in FIG. 2B, and a polishing cloth 45 on the surface of the polisher 44 of the CMP processing apparatus is held.
Press on and dressing.

In such a dresser 40, the abrasive grain layer 42
Since the upper surface of the polishing pad was formed flat, the outermost peripheral portion of the abrasive grain layer 42 was brought into linear contact with the polishing cloth 45 due to the deformation of the polishing cloth 45 by the pressing of the dresser 40, and only the outermost peripheral portion was quickly worn. There was a problem that it would end up. To address this problem, there has been proposed a dresser in which the cross-sectional shape of the abrasive grain layer is a convex arcuate curved surface or a mountain shape.

FIG. 6 shows a dresser proposed in Japanese Patent Application Laid-Open No. 11-300600, in which an outer peripheral portion 51a of a side surface of a disk-shaped base metal 51 is raised so that an upper surface thereof becomes an arc-shaped curved surface 51b. The abrasive grain layer 52 is formed on the curved surface 51b. By forming such an arc-shaped curved surface 51b, the abrasive grain layer 52 comes into surface contact with the polishing cloth, and the life of the dresser can be extended.
It is said that.

FIG. 7 shows a dresser proposed in Japanese Unexamined Patent Publication No. 10-277919, in which an outer peripheral side 61b and an inner peripheral side 61c of an upper surface are inclined surfaces on an outer peripheral portion 61a of a side surface of a disk-shaped base metal 61. The abrasive grain layer 62 is formed so that the intermediate portion 61d becomes a flat surface. It is said that the use of such a mountain-shaped abrasive grain layer 62 makes it possible to prevent the abrasive grains from falling off at the edge portion and to prevent the polishing cloth from being damaged.

[0010]

By the way, the dresser described in the above-mentioned publication uses the fact that, when the dresser is pressed against the polishing cloth at the time of dressing, the polishing cloth is elastically deformed in a depressed state due to the pressing force. Then, the cross-sectional shape of the abrasive grain layer is a convex arcuate curved surface or a mountain shape so that the abrasive grain layer is in surface contact with the polishing cloth. In addition, chip pockets are less likely to be formed during dressing, so that chips are not sufficiently discharged and the slurry for polishing the wafer is aggregated between the abrasive grains, resulting in the surface of the semiconductor wafer being CMP processed. There is a problem that micro scratches occur.
Further, since the dresser is a dresser in which the abrasive grains are fixed by the electrodeposition method, the protrusion amount of the abrasive grains is small, and the scraping rate is inferior to that in the case of fixing by brazing. The good dressing rate of the dresser means that the dressing rate of the dressing cloth is high when dressing.

The problem to be solved in the present invention is CMP.
In dressers for dressing polishing cloths used for surface finishing of semiconductor wafers by processing, while maintaining a cutting rate and processing accuracy equivalent to or better than conventional dressers, the ability to hold abrasive grains and discharge chips To improve.

[0012]

According to the dresser for CMP processing of the present invention, a plurality of rows of ridges are concentrically formed on the outer peripheral portion of the side surface of a disk-shaped base metal, and the outer peripheral side of the plurality of rows of ridges is formed. The height of the ridges is lower than the height of the ridges in the middle portion, and one layer of abrasive grains is fixed to the upper surfaces of these ridges by brazing.

By fixing the abrasive grains to the upper surface of the plurality of rows of concentric ridges by brazing to form an abrasive grain layer, a high abrasion rate is ensured and the gap between the ridges is increased. The groove becomes a concentric circle, and this groove serves as a discharge path for the slurry, and the slurry flows smoothly without agglomeration in the groove, and the problem that microscratches occur on the surface of the semiconductor wafer during CMP processing is also solved. Further, by forming the height of the ridges on the outer peripheral side to be lower than the height of the ridges on the intermediate portion, wear and falling due to concentrated contact pressure on the abrasive grains on the outer peripheral side which are most susceptible to load are suppressed, The life of the dresser is improved.

Here, of the plurality of rows of ridges, the height of the ridge on the outer peripheral side is made lower than the height of the ridge of the intermediate portion, and the height of the ridge on the inner peripheral side is set to the height of the intermediate portion. Can be formed lower than the height of. Further, the heights of the plurality of rows of ridges may be sequentially increased from the outer peripheral side toward the inner peripheral side. In the former case, the abrasive grains on the upper surface of the ridge come into contact with the polishing cloth along the elastic deformation of the polishing cloth, so that the number of working abrasive particles increases and a high abrasion rate and a long life can be obtained. In the latter case, the abrasive grains on the upper surface of the ridge, which gradually increase, are cut into the polishing cloth in a stepwise manner, so that the abrasion rate of the polishing cloth increases.

Further, by changing the direction of the edge portion of the abrasive grains to be fixed to the upper surface of the convex stripe for each convex stripe and fixing the abrasive grains to the upper surface of each convex stripe, the dressing machine as a whole has polishing performance of the polishing cloth. And a dresser that is excellent in processing quality and improves the processing quality of a semiconductor wafer. For example, the outermost ridge abrasive grain that acts most on polishing is fixed to the upper surface of the ridge with the edge of the abrasive grain facing straight up, and the inclination of the abrasive grain is suppressed as it goes to the inner peripheral side. The abrasive grains on the innermost peripheral ridge are fixed to the upper surface of the ridge in a posture in which the flat surface of the abrasive grains is in the upward direction, and thus the dresser as a whole is excellent in the scraping rate and the processed surface quality of the polishing cloth, It becomes a dresser that improves the processing quality of semiconductor wafers.

The direction of such abrasive grains can be adjusted by inclining the upper surface of each convex strip and fixing the abrasive grains in a specific posture. The slope of the upper surface of the ridge is an inclined surface with the upper surface of the ridge on the outer peripheral side inclined downward toward the outer circumference of the base metal, and the upper surface of the inner peripheral ridge is inclined downward toward the inner circumference of the base metal. The upper surface of the convex ridge in the middle part is a surface almost parallel to the side surface of the base metal, or the upper surface of the outer peripheral ridge is inclined downward toward the outer periphery of the base metal. The direction of the abrasive grains is adjusted by grading the slope of the upper surface of the ridge from the middle part toward the inner circumference side and making the upper surface of the inner ridge surface almost parallel to the side surface of the base metal. can do.

For example, the upper surface of the ridge on the outermost peripheral side is an inclined surface which faces downward toward the outer periphery, and the hexagonal octahedron of diamond abrasive grains or the (111) plane or (100) plane of a truncated octahedron.
When the surface is adhered to the upper surface of the ridge so as to be in close contact with it, the edge portion of the abrasive grains takes a posture in which the edge portion faces directly above.

Further, in the dresser for CMP processing of the present invention, the heights of the ridges of the plurality of rows may be sequentially changed in the circumferential direction of the base metal. For example, by forming the height of the ridges in a corrugated shape in the circumferential direction of the base metal,
A high-abrasive ridge abrasive grain causes the next-height ridge abrasive grain to act in a stepwise manner to obtain a high abrasion rate.

Further, it is possible to form grooves in the radial direction of the base metal at a plurality of locations on the ridges formed in a plurality of concentric rows on the outer periphery of the base metal. When such grooves are formed, the ridges are divided by the grooves in the radial direction, and as a result, the ridges form a large number of concentric and radially formed convex bodies on the outer periphery of the base metal. Become. In this case, the discharge of the slurry is further improved as compared with the case where the radial groove is not formed.

The dresser of the present invention can be manufactured according to the conventionally known dresser manufacturing process, except for the process of forming the convex strip or the convex body on the outer peripheral portion of the disk-shaped base metal.
The ridges and ridges can be formed by machining circumferential and radial grooves by electric discharge machining, turning, or polishing on the outer periphery of the raised base metal. A layer of abrasive grains is fixed to the upper surface of the sheet by brazing.

[0021]

1 is a front view of a base metal of a dresser according to an embodiment of the present invention, and FIG. 2 is a sectional view taken along line AA of FIG.

Base metal 10 for dresser in this embodiment
Raises the outer peripheral portion 12 of the side surface of the disk-shaped base metal body 11 to a higher level, and the outer peripheral portion 12 is concentrically formed on the outer peripheral portion 12 in five rows of ridges 1.
3a to 13e are formed. These ridges 13a to 13e
Is formed in a mountain shape in which the outer peripheral side (the ridge 13a side) and the inner peripheral side (the ridge 13e side) of the outer peripheral portion 12 are low and the intermediate portion (the ridge 13c) is high. These ridges 13a to 13e
Diamond abrasive grains are fixed to the upper surface of the above by brazing as described later. In FIG. 1, reference numeral 15 is a slit formed in the outer peripheral portion 12.

The base metal 10 is made of stainless steel, and each part has an outer diameter of 100 mm and the base metal part 11 has a thickness of 5 m.
m, the width of the outer peripheral portion 12 is 12 mm, the average thickness of the outer peripheral portion 12 is about 7 mm, the width of the ridges 13a to 13e is 2 mm, and the ridge 13a to
The average height of 13e is about 1.5 mm, and the difference in height between the ridges is 20 μm.

FIG. 3 is a view showing the shape of the outer peripheral portion of the base metal and the state in which the abrasive grains are fixed. In the figure, (a) is an example in which the upper surfaces of the ridges 13a to 13e are flat surfaces, and (b) and (c) are the ridges 1
In this example, the upper surfaces of 3a to 13e are inclined surfaces.

In FIG. 1A, the outer peripheral portion 12 on the side surface of the base metal body 11 is raised to a higher level.
5 rows of ridges 13a to 13e are formed concentrically. The heights of the ridges 13a to 13e are mountain-shaped such that the outer peripheral side (the ridge 13a side) and the inner peripheral side (the ridge 13e side) of the outer peripheral portion 12 are low and the intermediate portion (the ridge 13c) is high. Is formed. The upper surface of each of the ridges 13a to 13e is a flat surface, and the diamond abrasive grains 14a to 14e are formed on these flat surfaces.
Are arranged in a grid at regular intervals and are fixed by brazing. In this example, the postures of the abrasive grains 14a to 14e on the respective ridges 13a to 13e are the same, and the abrasive grains 14a to 14e are the same.
The sharpness and wear of a to 14e are almost the same.

In FIG. 6B, the abrasive grains 14a of the outermost ridge 13a, which is most abrasive, are the abrasive grains 14a.
Is fixed to the upper surface of the ridge 13a with the edge portion of the ridge facing upward, and the inclination of the abrasive grains is suppressed toward the inner peripheral side, and the abrasive grains 14e of the innermost ridge 13e are flattened with the abrasive grains 14e. By fixing the ridge 13e to the upper surface with the surface facing upward,
The dresser as a whole has excellent grinding performance. In order to have such a posture of the abrasive grains, the upper surface of the outermost ridge 13a is largely inclined toward the outer peripheral side, and the inclination of the upper surface of the ridge is gradually reduced toward the inner peripheral side so that the innermost peripheral side is inclined. The upper surface of the ridge 13e is a flat surface without inclination.

In FIG. 3C, the ridges 13a to 1 are formed.
The height of 3e is formed in a mountain shape in which the outer peripheral side and the inner peripheral side are low and the middle part is high, and the upper surface of the outer peripheral side convex line is inclined downward toward the outer peripheral side and the upper surface of the inner peripheral side convex line. Is a surface inclined downward toward the inner peripheral side. In this example, each ridge 1
The postures of the abrasive grains 14a to 14e in 3a to 13e are different, and the abrasive grains on the surface having a large inclination have a posture in which the edge portion is upward due to the inclination of the abrasive grains, and the dresser has an excellent scraping rate.

FIG. 4 is a partially enlarged view of a dresser according to another embodiment of the present invention. (A) of the same figure shows the formation state of the ridges and grooves on the outer peripheral portion of the base metal, and (b) is an end view taken along line BB of (a).

In the dresser of this embodiment, the outer peripheral portion of the base metal body 11 has a cross-sectional shape in the radial direction of the base metal as shown in FIG. 3 (b) and a circumferential direction of the base metal as shown in FIG. 4 (b). By forming the grooves 18 in the radial direction and the grooves 19 in the circumferential direction, a large number of concentric and radial convex bodies 16 are formed on the outer peripheral portion of the base metal. Diamond abrasive grains 17 are fixed to the upper surface of 16. By forming the height of the convex body 16 in a corrugated shape in the circumferential direction of the base metal, the scraping rate is further improved, and by forming the grooves 18 and 19, the discharge of the slurry is further improved.

[Test Example] In the plan view shown in FIG.
The dresser (invention product 1) in which diamond abrasive grains are fixed to the upper surface of each convex strip of the base metal having the sectional shape of the outer peripheral portion shown in (b) and the base metal of each convex strip of the inventive product 1 in the circumferential direction of FIG. ) Shown in FIG. 4B and the wavy shape shown in FIG. 4B in the circumferential direction of the base metal, and FIG. 3B in the radial direction of the base metal. The dresser (invention product 3) in which each of the raised and lowered convex bodies shown in FIG.
The dresser (conventional product 1) having the shape (see FIG. 7) described in Japanese Unexamined Patent Publication No.
A dressing test was performed using a dresser (conventional product 2) having the shape (see FIG. 6) described in JP-A-1-300600. The test conditions are as follows. Dresser specifications: Base metal size φ100 × 12W, grain size # 100/120, brazing material Ni-Cr-Co Machine used: Takuma machine Polishing pad: Polyurethane foam outer diameter 300mm Dresser rotation speed: 20min ^-1 Table rotation speed: 30min ^-1 Processing pressure: 50N Processing time: 20 hours

The test results are shown in Table 1.

[Table 1]

In Table 1, the characteristic values in the table are those of the conventional product 1
It is represented by an index when the measured value of is set to 100. Here, the scraping rate uses the amount of polishing cloth removed per hour during dressing as an index, the service life uses the dresser usage time when the scraping rate is below the lower limit, and the processing accuracy is the processing of the workpiece. The accuracy was used as an index. As can be seen from Table 1, the invention product in which the ridge is formed on the outer peripheral portion of the base metal has a significantly improved scraping rate and life compared with the conventional products 1 and 2 while maintaining the processing accuracy.

[0033]

EFFECTS OF THE INVENTION (1) A high abrasion rate is secured by fixing abrasive grains to the upper surface of a plurality of rows of concentric circular ridges formed on the outer periphery of the side surface of a disk-shaped base metal to form an abrasive grain layer. In addition, concentric circular grooves are formed between the ridges, and these grooves serve as a chip discharge path to improve the chip discharge effect, allowing the slurry to flow smoothly without agglomeration in the grooves. , The problem that microscratches occur on the surface of a semiconductor wafer during CMP processing is also solved. Further, by forming the height of the ridges on the outer peripheral side to be lower than the height of the ridges on the intermediate portion, wear and falling due to concentrated contact pressure on the abrasive grains on the outer peripheral side that are most susceptible to load are suppressed, The life of the dresser is improved.

(2) By forming the height of the ridges on the outer peripheral side to be lower than the height of the ridges on the intermediate portion and the height of the ridges on the inner peripheral side to be lower than the height of the ridges on the intermediate portion. A high abrasion rate and a long life can be obtained by increasing the abrasion rate of the polishing pad and forming the height of the ridges from the outer peripheral side to the inner peripheral side in order.

(3) By changing the direction of the edge portion of the abrasive grains to be fixed to the upper surface of the convex stripe for each convex stripe and fixing the abrasive grains to the upper surface of each convex stripe, the dresser as a whole has excellent grinding performance, To improve the processing quality of semiconductor wafers.

(4) By sequentially changing the heights of the ridges in a plurality of rows in the circumferential direction of the base metal, the wear rate of the dresser increases, and the ridges in a plurality of rows have grooves in the base metal radial direction at a plurality of locations. By forming it, the effect of discharging the slurry and chips is enhanced, and a high scraping rate and a long life can be obtained.

[Brief description of drawings]

FIG. 1 is a front view of a base metal of a dresser according to an embodiment of the present invention.

FIG. 2 is a sectional view taken along line AA of FIG.

FIG. 3 is a partial cross-sectional view showing a shape of an outer peripheral portion of a base metal and a state where abrasive grains are fixed to the base metal.

FIG. 4 is a partial enlarged view of a dresser according to another embodiment of the present invention.

FIG. 5 is a diagram showing an example of a conventional dresser and its usage state.

FIG. 6 is a diagram showing an improved example of a conventional dresser.

FIG. 7 is a diagram showing another modified example of the conventional dresser.

[Explanation of symbols]

10 money 11 Main body 12 Outer periphery 13a to 13e convex stripes 14a to 14e, 17 diamond abrasive grains 15 slits 16 Convex body 18,19 groove

Continuation of the front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) H01L 21/304 622 H01L 21/304 622M (72) Inventor Yasushi Inoue 210 No. Takeno, Tanamaru-cho, Ukiha-gun, Fukuoka Noritake Co., Ltd. F term in superabrasive (reference) 3C047 EE02 EE11 EE18 3C058 AA04 AA09 AA19 CB01 CB03 DA13 3C063 AB05 BA26 BB02 BC02 BG07 BH05 EE26 FF20 FF22

Claims (8)

[Claims] 1. A plurality of rows of ridges are formed concentrically on the outer periphery of the side surface of the disk-shaped base metal, and the height of the ridges on the outer peripheral side of the plurality of rows of ridges A dresser for CMP processing, characterized in that it is formed to be lower than the height, and one layer of abrasive grains is fixed to the upper surface of these ridges by brazing. 2. The dresser for CMP processing according to claim 1, wherein the height of the protrusion on the inner peripheral side of the plurality of rows of protrusions is formed lower than the height of the protrusion in the middle portion. 3. The dresser for CMP processing according to claim 1, wherein the heights of the plurality of rows of ridges are sequentially increased from the outer peripheral side toward the inner peripheral side. 4. The dresser for CMP processing according to claim 1, wherein the direction of the edge portion of the abrasive grains to be fixed to the upper surface of the convex line is changed for each convex line, and the abrasive grains are fixed to the upper surface of each convex line. 5. The upper surface of the protrusion on the outer peripheral side is an inclined surface which is inclined downward toward the outer periphery of the base metal, and the upper surface of the protrusion on the inner peripheral side is inclined downward toward the inner periphery of the base metal. 5. The dresser for CMP processing according to claim 2 or 4, wherein the inclined surface is an inclined surface, and the upper surface of the convex stripe in the middle portion is a surface substantially parallel to the side surface of the base metal. 6. The upper surface of the ridge on the outer peripheral side is an inclined surface which is inclined downward toward the outer circumference of the base metal, and the inclination of the upper surface of the ridge is gradually reduced from the middle portion toward the inner peripheral side to form an inner peripheral surface. The upper surface of the side convex strip is a surface substantially parallel to the side surface of the base metal.
Alternatively, the dresser for CMP processing according to item 4. 7. The CM according to claim 1, wherein the heights of the ridges of the plurality of rows are sequentially changed in the circumferential direction of the base metal.
Dresser for P processing. 8. The C according to claim 1, wherein grooves in the base metal radial direction are formed at a plurality of locations on the plurality of rows of ridges.
Dresser for MP processing.