WO2018142623A1

WO2018142623A1 - Polishing pad recess forming method and polishing pad

Info

Publication number: WO2018142623A1
Application number: PCT/JP2017/004259
Authority: WO
Inventors: 邦晴大石; 達広海野
Original assignee: 株式会社大輝
Priority date: 2017-02-06
Filing date: 2017-02-06
Publication date: 2018-08-09
Also published as: CN109562506A; JP6324637B1; JPWO2018142623A1; CN109562506B

Abstract

[Problem] To provide a high-quality polishing pad that satisfies a user's demand regarding recesses. [Solution] First, a tool (6) that has a projected shape conforming to the shape of a recess to be formed on the front surface of a polishing pad (7) is arranged on a work surface (2a). Then, the polishing pad (7) is arranged on the work surface (2a) on which the tool (6) has been arranged. The polishing pad (7) is sucked from the back surface via a suction hole (2b), and the front surface raised in accordance with the projected shape of the tool (6) is partially removed in the thickness direction while bending the polishing pad (7) which is supported in the state of being suspended by the projected part of the tool (6). Thus, a recess is formed in the front surface of the polishing pad (7).

Description

Method of forming recess of polishing pad and polishing pad

The present invention relates to a method for forming a recess of a polishing pad used for polishing an object to be polished and a polishing pad.

Conventionally, a sheet-like abrasive called a polishing pad has been widely used to polish semiconductor wafers cut from ingots and intermediate products produced in the manufacturing process of precision equipment represented by semiconductor integrated circuits. ing. A polishing pad having a concave portion such as a streak-like groove formed on the surface is also known, and various methods have been proposed for forming the concave portion. For example, in the method disclosed in Patent Document 1, a concavo-convex shape is formed on the surface of the polishing sheet using a sand blasting method in which a fine abrasive is sprayed. Further, Patent Document 1 discloses a method for forming a concavo-convex shape in a heating embossing process, and a method for curing after applying and embossing a non-adhesive reactive resin instead of the sandblasting method. .

In the method disclosed in Patent Document 2, first, a lower layer formed into a disk shape and an upper layer having the same shape as the lower layer are prepared, and the upper layer is cut radially. At that time, the width of the cut is matched with the width of the groove to be formed. Next, a pad piece cut into a fan shape is pasted on the lower layer. As a result, radial grooves are formed on the surface of the polishing pad.

Patent Document 3 discloses a method of forming a narrow groove on the surface of a semiconductor CMP processing pad by cutting a urethane foam pad with a milling cutter. Patent Document 4 discloses a method of forming a recess on the surface of a polishing layer included in a polishing sheet using a printing method such as screen printing, gravure printing, or gravure offset printing.

On the other hand, Patent Document 5 discloses a method of forming a CMP pad (porous polishing pad) using laser sintering. The method includes focusing a laser beam from a laser into a sintering nozzle and injecting fluidized thermoplastic particles into the sintering nozzle through an injection port. The thermoplastic particles are sintered with a laser beam, and the sintered thermoplastic particles are selectively deposited on a plate. Thereby, the part which is not deposited becomes a groove.

Further, in the method disclosed in Patent Document 6, first, a coating film is formed by applying a resin solution onto a precursor sheet-forming substrate having an uneven shape. This coating film is formed so as to follow the uneven shape of the substrate and the coating film surface becomes flat. Next, the base material is attached to the resin sheet from which the base material has been peeled off from the structure via an adhesive layer. Then, the skin layer region is curved / bent in the thickness direction by pressing the skin layer region portion toward the pressure-sensitive adhesive layer side using a press. Thereby, a groove is formed on the skin layer region side of the resin sheet.

Furthermore, in the method disclosed in Patent Document 7, first, a polishing sheet having a large number of vertically long bubbles is formed using a wet film forming method. Next, the surface of the polishing sheet where the bubbles are reduced in diameter is ground or sliced to open the tear-type bubbles on the polishing surface of the polishing sheet. And the protective sheet which suppresses a temperature rise is arrange | positioned at the opened grinding | polishing surface. Finally, the heated mold is pressed against the surface on which the protective sheet is disposed. Since this mold has a convex portion of a predetermined shape, a groove corresponding to the concave portion of the mold is formed on the polishing surface by this pressing.

JP 2001-113467 A JP 2002-100592 A JP 2002-11630 A JP 2003-103470 A JP 2007-281435 A JP 2013-208687 A JP 2013-208687 A

Since the quality of the polishing pad has a great influence on the yield of objects to be polished using the polishing pad, in recent years, the required specifications from the user side who uses the polishing pad are increasing. As such a requirement, it is possible to respond flexibly to diversification of specifications including complicated concave patterns, and the concave portions (grooves) formed by cutting with a cutter are preferable because the inner surfaces of the concave portions are roughened. If the unevenness is square, the object to be polished is caught during polishing, which is not preferable.

The present invention has been made in view of such circumstances, and an object of the present invention is to provide a high-quality polishing pad that meets the user's request regarding the recess.

In order to solve this problem, the first invention provides a method of forming a recess in the surface of a polishing pad. In this method, first, as a first step, a polishing pad is disposed on the work surface. The work surface is provided with a convex pattern corresponding to the concave pattern to be formed on the surface of the polishing layer provided in the polishing pad. Next, as a second step, the surface of the polishing layer raised according to the convex pattern on the work surface is partially removed in the thickness direction while applying an external force to the polishing pad to bend the polishing pad. Thereby, a recess is formed on the surface of the polishing layer.

Here, in the second step of the first invention, a suction force for sucking the polishing pad from the back surface through a plurality of suction holes provided in the work surface may be used as the external force. In this case, the first step may include a step of placing a jig on the work surface prior to placement of the polishing pad on the work surface. This jig has a base member and a protrusion. The base member has a shape corresponding to the surface shape of the polishing pad and has air permeability. The protrusion is attached to protrude from the surface of the base member, and has a convex pattern corresponding to the concave pattern to be formed on the surface of the polishing layer. Further, in this case, the jig disposed on the work surface is removed, the polishing pad is rearranged on the work surface, and the surface of the polishing layer excluding the recess is ground to form a flat polishing surface. These steps may be further provided. In this case, it is preferable that the second step and the step 3 are performed using the same grinding machine.

In the first invention, the removal of the polishing layer in the second step is preferably performed by grinding only the raised surface of the polishing layer. In this case, it is desirable that the second step includes a step of sucking and removing dust generated by grinding the raised surface of the polishing layer.

The second invention provides a polishing pad provided with a polishing layer. The polishing layer has a flat polishing surface that is a part of the surface, a concave portion that is partially provided on the surface, and that is recessed from the surface, and a flat back surface that is opposite to the surface. The thickness of the polishing layer gradually decreases from the polishing surface toward the recess. Further, the rate of change of the thickness of the polishing layer gradually increases from the polishing surface toward the side wall surface of the recess, and gradually decreases from the side wall surface of the recess toward the bottom surface of the recess.

Here, in the second invention, the roughness of the side wall surface and the bottom surface of the recess may be the same as the roughness of the polished surface. Moreover, it is preferable that the said recessed part is a groove | channel extended on the surface in the shape of a line.

According to the first invention, since a cutter that causes roughening of the inner surface of the recess is not used, a fine surface equivalent to or close to the polished surface can be obtained as the inner surface of the recess. In addition, since there are no angular irregularities on the surface of the polishing layer, the object to be polished is hardly caught when polishing using a polishing pad. In particular, if a jig having a convex pattern is used, the concave pattern of the polishing pad can be flexibly formed with a high degree of freedom by exchanging the jig.

According to the second invention, the thickness of the polishing layer is gradually decreased from the polishing surface toward the concave portion, and there is no angular irregularity on the surface of the polishing layer. Therefore, when polishing with the polishing pad, The object to be polished is not easily caught. Further, since the profile relating to the thickness of the polishing layer is specific to the method according to the first invention, it is effective whether or not the polishing pad is created by using the method according to the first invention through observation of the profile. Can be judged.

Configuration diagram of polishing pad processing equipment Illustration of jig placement process Jig configuration diagram Explanation of polishing pad placement process Cross section of polishing pad The figure which shows the arrangement | positioning state of a polishing pad Illustration of grinding process The figure which shows the polishing pad completed through a series of processes Enlarged cross-sectional photo of polishing pad Characteristic diagram showing the profile of thickness in the groove width direction Characteristic diagram showing profile of thickness by cutting Cross-sectional view of a polishing pad in the prior art Illustration of alternative technology for suction process

FIG. 1 is a configuration diagram of a polishing pad processing apparatus. This processing apparatus 1 is mainly composed of a work table 2, a suction machine 3, and a grinding machine 4. A work frame 2 provided in the work table 2 is fixed with a frame 5 for positioning a disc-shaped polishing pad or the like. The work surface 2a is provided with a number of suction holes 2b that penetrate the work table 2 up and down. The suction machine 3 is disposed under the work table 2. The suction machine 3 communicates with a number of suction holes 2b provided in the work table 2, and sucks the polishing pad held in the table frame 5 from the back surface thereof.

The grinding machine 4 is disposed above the work table 2 so as to face the work surface 2a, and is movable in a three-dimensional direction by an actuator (not shown). The grinding machine 4 includes a rotary roller 4a and a dust suction machine 4b. Diamond powder is fixed to the outer peripheral surface of the roller 4a. By rotating the roller 4 a while moving the grinding machine 4, the object to be ground (polishing pad) in contact with the outer peripheral surface of the roller 4 a is ground into a flat shape (to be ground). The dust suction machine 4b sucks and removes dust generated by grinding with the roller 4a. The dust sucked by the dust suction machine 4b is discharged to the outside through a hose 4c attached to the grinding machine 4.

Next, a method for forming a recess on the surface of the polishing pad using the polishing pad processing apparatus 1 will be described. As the concave portion, a groove extending in a streak shape or a depressed portion provided in the vicinity of the outer periphery of the polishing pad is assumed.

As shown in FIG. 2, prior to the processing of the polishing pad 7, a disk-shaped jig 6 is arranged in a frame 5 fixed on the work surface 2a. FIG. 3 is a configuration diagram of the jig 6. The jig 6 includes a base member 6a and a protruding portion 6b. The base member 6a has a shape (disk shape) corresponding to the surface shape of the polishing pad. The base member 6a is formed of a material having air permeability (for example, polyurethane) so as not to hinder the suction of the polishing pad through the suction hole 2b. However, as the base member 6a, even if the material itself does not have air permeability, a material that allows ventilation, such as a metal mesh, may be used. Further, the protruding portion 6b is attached to the base member 6a so as to protrude upward from the surface of the base member 6a. The protrusion 6b has a convex shape (convex pattern) corresponding to the shape of the concave portion (concave pattern) to be formed on the surface of the polishing layer provided in the polishing pad. The protrusion 6b is formed of an acrylic material as an example. By using a material that can be easily cut by laser, such as an acrylic material, the protruding shape of the protruding portion 6b can be freely formed with a high degree of freedom including straight lines, curved lines, and combinations thereof. In this embodiment, in order to form a turtle shell-shaped concave pattern on the surface of the polishing pad, the protruding portion 6b also has a turtle shell-shaped convex pattern.

As shown in FIG. 4, a disc-shaped polishing pad 7 is disposed on the work surface 2a (within the frame 5) on which the jig 6 is disposed. FIG. 5 is a cross-sectional view of the polishing pad 7. The polishing pad 7 is mainly composed of a polishing layer 7a, an adhesive layer 7b, and a release sheet 7c in order from the top layer, and is cut (formed) into a disk shape in this embodiment. Further, the polishing pad 7 has a property of bending itself, that is, flexibility. The polishing layer 7a is a layer having a function of polishing an object to be polished, which is a central function of the polishing pad 7, and is made of, for example, polyurethane (foamed urethane). For example, a double-sided tape can be used as the adhesive layer 7b. When the user attaches the polishing pad 7 to the polishing apparatus, the lowermost release sheet 7c is peeled to expose the adhesive layer 7b, and then the polishing pad 7 is attached to a predetermined part of the polishing apparatus.

FIG. 6 is a view showing a state in which the polishing pad 7 is disposed on the work surface 2a via the jig 6. As shown in FIG. When the suction machine 3 is stopped, the polishing pad 7 is lifted by the height of the protrusion 6b, and there is a space between the polishing pad 7 and the base member 6a. Due to the presence of this space, when an external force is applied to the polishing pad 7 in the next step, partial deflection of the polishing pad 7 that is lifted from the work surface 2a is allowed.

Next, while the polishing pad 7 is bent by applying an external force (suction force) to the polishing pad 7, the surface of the polishing layer 7a is partially ground and removed in the thickness direction. FIG. 7 is an explanatory diagram of a grinding process of the polishing pad 7. In this step, the suction machine 3 is operated to suck the polishing pad 7 from the back surface through the plurality of suction holes 2b facing the work surface 2a. As a result of this suction force acting on the polishing pad 7 as an external force, a portion of the surface of the polishing pad 7 that is in a state of being lifted by the adjacent protrusions 6b is bent, and the upper surface of the base member 6a disposed below and Contact. That is, the surface of the polishing pad 7 (polishing layer 7a) is depressed only at the part that has been lifted, and as a result, the part supported by the protruding portion 6b is relatively raised.

Then, while maintaining the state where the polishing pad 7 is bent, the grinding machine 4 set to a predetermined height is moved in parallel with the work surface 2a, and the polishing layer which is the uppermost layer of the polishing pad 7 is formed by the roller 4a. The surface of 7a is partially ground, that is, only the raised portion is ground by a predetermined thickness α (grinding step). Here, the following two conditions are required as conditions for preventing the grinding process by the grinding machine 4 from being hindered. First, if the height reference is the work surface 2a, the height H1 of the underframe 5 is lower than the sum of the jig height H2 and the thickness D of the polishing pad 7 (before grinding). is there. Second, the height H3 (= H2 + D−α) after grinding of the polishing pad 7 is higher than the height H1 of the underframe 5. When the suction machine 3 is stopped after grinding, the bending deformation of the polishing pad 7 is eliminated by its own restoring force. Thereby, the back surface opposite to the surface of the polishing pad 7 (polishing surface 7a) is restored to a flat state, and a concave portion corresponding to the grinding is generated on the surface.

In this grinding process, dust generated by grinding the raised surface of the polishing layer 7a is sucked and removed by operating the dust suction device 4b included in the grinding machine 4a. In this step, the partial removal of the polishing layer 7a may be performed by using a slicing process that thinly slices the surface of the grinding layer 7a instead of the grinding process.

Finally, the finishing process of the polishing pad 7 is performed. In the finishing process, the jig 6 arranged on the work surface 2a is removed, and the polishing pad 7 is rearranged on the work surface 2a. Then, the surface of the polishing layer 7a excluding the concave portion 7d is thinly ground by using the same grinding machine 4 as in the grinding step, thereby forming a flat polishing surface as a part of the surface of the polishing layer 7a. In the finishing process, it is preferable to operate the suction machine 3 to suck the polishing pad 7 from the back surface through the plurality of suction holes 2b facing the work surface 2a. This is because an effect of removing the peculiarity caused by bending and deforming the polishing pad 7 in the previous step can be expected.

FIG. 8 is a view showing the polishing pad 7 completed through a series of steps. In the polishing pad 7, the uppermost polishing surface 7 a has a flat polishing surface 7 d that is a part of the surface, and a recess 7 e that is partially provided on the surface and is recessed from the surface (polishing surface 7 d). . A shape corresponding to the convex pattern of the jig 6 is transferred as the shape (concave pattern) of the concave portion 7e. Further, as described above, the surface of the polishing layer 7a has irregularities, but the back surface thereof is flat.

FIG. 9 is an enlarged cross-sectional photograph of the polishing pad 7. Here, A is the maximum thickness (1.402 mm) of the polishing layer 7a, B is the width of the recess (groove) (3.786 mm), and C is the depth of the recess 7e (0.246 mm). As can be understood from this photograph, the surface changes gently from the polishing surface 7d toward the recess 7e, and there is no angular portion. As a result, it is possible to effectively prevent the object to be polished from being caught during polishing. Further, the inner surface of the recess 7e does not have the roughness as in the case of cutting with a cutter, and is in a fine state equivalent to or close to the roughness of the polishing surface 7d. In particular, when grinding and finishing are performed using the same grinding machine 4, the roughness of the inner surface (side wall surface and bottom surface) of the recess is the same as the roughness of the polished surface.

FIG. 10 is a characteristic diagram showing a profile of the thickness D of the polishing layer 7a with respect to the length X in the groove width direction. The thickness D of the polishing layer 7a is gradually decreased from the polishing surface 7d toward the recess 7e. Further, the change rate ΔD, that is, the inclination of the thickness D gradually increases from the polishing surface 7d toward the side wall surface of the recess 7e, and gradually decreases from the side wall surface of the recess 7d toward the bottom surface thereof. is doing.

As described above, according to the present embodiment, a cutter that causes roughening of the inner surface of the recess 7e of the polishing pad 7 is not used, so that a fine surface equivalent to or close to the polishing surface 7e can be obtained as the inner surface of the recess 7e. Can do. Further, since there are no angular irregularities on the surface of the polishing layer 7a, the object to be polished is not easily caught when polishing by the polishing pad 7 by the user.

According to the present embodiment, the concave pattern of the polishing pad 7 can be flexibly formed with a high degree of freedom by replacing the jig 6 for transferring the concave pattern to the polishing pad 7 with a different convex pattern. can do. However, if compatibility with various concave patterns is not required, the convex pattern may be directly formed on the work surface 2a without using the replaceable jig 6.

In addition, according to the present embodiment, the profile relating to the thickness D of the polishing layer 7a is unique to the processing method according to the present embodiment. It is possible to effectively determine whether the polishing pad is created using the processing method. In the case of cutting with a cutter or the like, as shown in FIG. 11, basically, at the boundary portion A between the polishing surface and the sidewall surface of the recess, and at the boundary portion B between the sidewall surface of the recess and the bottom surface thereof, the polishing layer The thickness D changes rapidly. Further, the side wall surface of the recess is also vertical and does not have the inclination as shown in FIG. Even if the boundary portion B becomes gentle depending on the shape of the cutting edge of the cutter, the boundary portion A does not become gentle. This point is not limited to the cutter, and is the same in all methods based on linear cutting such as laser processing and sandblasting. In addition, Patent Document 6 listed as the prior art discloses a polishing pad in which the surface of the skin layer region corresponding to the polishing layer is gently connected as shown in FIG. It is similar to the polishing pad 7 according to this embodiment in that there is no unevenness. However, paying attention to the change in the thickness of the polishing layer, the skin layer region of Patent Document 6 has a constant thickness and does not have a profile as shown in FIG. From the above, it can be said that the profile of FIG. 10 is unique to a processing method in which surface grinding is performed while the polishing layer is bent and deformed.

In the above-described embodiment, the example in which the suction force applied through the suction hole 2b is used as the external force for bending the polishing pad 7 in the grinding process has been described. However, the present invention is not limited to this. For example, as shown in FIG. 13, the magnetic force of the magnet 8 may be used. In this case, a metal mesh or the like is used as the base member 6a, and the magnet 8 is disposed between the adjacent protruding portions 6. The polishing pad 7 is bent by the magnetic force generated between the magnet 8 and the base member 6 a, and as a result, a bump corresponding to the convex shape of the jig 6 is generated on the surface of the polishing pad 7. Further, instead of the magnet 8, a weight may be used and the polishing pad 7 may be bent with its own weight as an external force. Further, the polishing pad 7 may be bent by pressing both ends of the polishing pad 7 against the work surface 2a.

Further, in the above-described embodiment, the polishing layer 7a, the adhesive layer 7b, and the release sheet 7c are laminated and cut (formed) into a disk shape. The polishing layer 7a before lamination may be a single body or a sheet body before cutting. From this point of view, the term “polishing pad 7” in the present specification is used in a sense including such a thing widely.

Furthermore, in the above-described embodiment, the example in which the polishing layer 7a is ground by moving the grinding machine 4 (roller 4a) with respect to the polishing pad 7 disposed on the work surface 2a has been described. However, the present invention is not limited to this, and the polishing pad 7 may be moved with respect to the grinding machine 4. Further, the upper surface of the work table 2 may be curved. In this case, the portion of the curved surface of the work table 2 where the polishing layer 7a and the grinding machine 4 are in contact with each other can be regarded as the “work surface 2a”.

The polishing pad manufactured according to the present invention is widely applied to the use of polishing an object to be polished including a semiconductor wafer cut out from an ingot and an intermediate product generated in the manufacturing process of precision equipment represented by a semiconductor integrated circuit. be able to.

DESCRIPTION OF SYMBOLS 1 Polishing pad processing apparatus 2 Worktable 2a Work surface 2b Suction hole 3 Suction machine 4 Grinding machine 4a Roller 4b Dust suction machine 4c Hose 5 Base frame 6 Jig 6a Base member 6b Protruding part 7 Polishing pad 7a Polishing layer 7b Adhesive layer 7c Release sheet 7d Polishing surface 7e Concave part

Claims

In the method of forming the recess of the polishing pad,
A first step of disposing the polishing pad on a work surface provided with a convex pattern corresponding to the concave pattern to be formed on the surface of the polishing layer provided in the polishing pad;
The surface of the polishing layer raised according to the convex pattern on the work surface is partially removed in the thickness direction while applying an external force to the polishing pad to bend the polishing pad. And a second step of forming the concave portion on the surface thereof.
The said 2nd step WHEREIN: As the said external force, the suction force which attracts | sucks the said polishing pad from the back surface through the several suction hole provided in the said work surface is used. A method for forming a recess in a polishing pad.
The first step includes a step of placing a jig on the work surface prior to placement of the polishing pad on the work surface;
The jig is
A base member having a shape corresponding to the surface shape of the polishing pad and having air permeability;
The polishing pad according to claim 2, further comprising: a protruding portion attached to protrude from the surface of the base member and having a convex pattern corresponding to the concave pattern to be formed on the surface of the polishing layer. The method of forming a recess.
The jig disposed on the work surface is removed, the polishing pad is rearranged on the work surface, and the surface of the polishing layer excluding the recess is ground to form a flat polishing surface. The method for forming a recess of a polishing pad according to claim 3, further comprising: 3 steps.
5. The method for forming a recess of a polishing pad according to claim 4, wherein the second step and the step 3 are performed using the same grinding machine.
2. The polishing pad recess forming method according to claim 1, wherein the removal of the polishing layer in the second step is performed by grinding only the raised surface of the polishing layer.
The method for forming a recess of a polishing pad according to claim 6, wherein the second step includes a step of sucking and removing dust generated by grinding the raised surface of the polishing layer.
In polishing pad,
A flat polished surface that is part of the surface;
A concave portion partially provided on the surface and recessed from the surface;
A polishing layer having a flat back surface opposite to the front surface;
The thickness of the polishing layer gradually decreases from the polishing surface toward the recess,
The rate of change of the thickness of the polishing layer gradually increases from the polishing surface toward the sidewall surface of the recess, and gradually decreases from the sidewall surface of the recess toward the bottom surface of the recess. Polishing pad characterized by
The polishing pad according to claim 8, wherein the roughness of the side wall surface and the bottom surface of the recess is the same as the roughness of the polishing surface.
The polishing pad according to claim 8, wherein the recess is a groove extending in a streak pattern on the surface.