JP2012240189A - Polishing apparatus, polishing method, and polishing pad - Google Patents

Abstract

PROBLEM TO BE SOLVED: To keep the flatness of a polishing pad in a polishing process.SOLUTION: The polishing apparatus 10 includes a platen 100, the polishing pad 120 disposed on the platen 100, and an adhesive layer 160 fixing the polishing pad 120 and the platen 100. The polishing pad 120 has a groove 122 extended to the end face of an outer periphery on a rear face opposite to one face with which a substrate 20 to be polished comes in contact.

Description

  The present invention relates to a polishing apparatus, a polishing method, and a polishing pad.

  2. Description of the Related Art In recent years, a CMP (Chemical Mechanical Polishing) method has been adopted for planarizing an interlayer insulating film in a semiconductor device manufacturing process.

  Patent Document 1 (Japanese Unexamined Patent Application Publication No. 2007-118106) describes a polishing pad made of the following polyurethane resin foam. The through hole formed in the polishing layer is provided with a window for detecting the end point. A strain absorbing groove is formed outside the window portion of the polishing layer. As described above, by providing the strain absorbing groove, the polishing pad is prevented from being distorted due to a dimensional change caused by shrinkage, expansion or swelling of the window portion or the polishing layer during molding or CMP processing. It is supposed to be possible.

  Patent Document 2 (Japanese Patent Application Laid-Open No. 2003-303793) describes the following polishing apparatus. This polishing apparatus includes a polishing pad in which a plurality of grooves communicating with the polishing surface plate are formed on the bonding surface of the first layer with the second layer. By applying a negative pressure to the groove, a recess for introducing a slurry is formed on the surface of the second layer of the polishing pad. Accordingly, it is said that the polishing pad is not easily consumed, and polishing can be performed while maintaining the uniformity of the polishing amount over a long period of time.

JP 2007-118106 A JP 2003-303793 A

  The above-described polishing pad is attached to a polishing surface plate (a platen described later) with an adhesive layer or the like. The inventor has found that in the polishing process, organic gas is generated from the adhesive layer due to heat generated by polishing, and bubbles are generated at the interface between the polishing pad and the adhesive. When such bubbles are generated, there is a possibility that the substrate to be polished is lifted from the polishing pad. Therefore, it has been found that the contact between the substrate to be polished and the polishing pad becomes unstable, and defects such as polishing abnormality and substrate cracking occur.

According to the present invention,
The platen,
A polishing pad provided on the platen and provided with a groove extending to the outer peripheral end surface on the back surface opposite to the one surface in contact with the substrate to be polished;
An adhesive layer for fixing the polishing pad and the platen;
A polishing apparatus is provided.

According to the present invention,
The platen,
A polishing pad provided on the platen and provided with a groove extending to the outer peripheral end surface on the back surface opposite to the one surface in contact with the substrate to be polished;
An adhesive layer for fixing the polishing pad and the platen;
Using a polishing apparatus comprising
A polishing method is provided in which a polishing surface of the substrate is brought into contact with and polished on the polishing pad.

According to the present invention,
A polishing pad for polishing a substrate,
A polishing pad is provided that has a groove extending to the outer peripheral end surface on the back surface opposite to the one surface that contacts the substrate to be polished.

  According to the present invention, the back surface of the polishing pad is provided with a groove extending to the outer peripheral end surface. Thereby, even if organic gas is generated from the pressure-sensitive adhesive layer due to heat generation in the polishing process, it can escape from the groove. For this reason, it is possible to suppress the generation of bubbles at the interface between the polishing pad and the adhesive layer. Therefore, the flatness of the polishing pad can be maintained in the polishing process.

  According to the present invention, the flatness of the polishing pad can be maintained in the polishing step.

It is a figure showing composition of a polish device concerning a 1st embodiment. It is a figure showing composition of a polish device concerning a 1st embodiment. It is sectional drawing to which the B section of FIG.2 (b) was expanded. It is a top view of the back surface of the polishing pad which concerns on 2nd Embodiment. It is a top view of the back surface of the polishing pad which concerns on 3rd Embodiment. It is a top view of the back surface of the polishing pad which concerns on 4th Embodiment.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In all the drawings, the same reference numerals are given to the same components, and the description will be omitted as appropriate.

(First embodiment)
The polishing apparatus 10 according to the first embodiment will be described with reference to FIGS. The polishing apparatus 10 includes a platen 100, a polishing pad 120 provided on the platen 100, and an adhesive layer 160 that fixes the polishing pad 120 and the platen 100. The polishing pad 120 is provided with a groove 122 extending to the outer peripheral end surface on the back surface opposite to the one surface with which the substrate 20 to be polished contacts. Details will be described below.

  First, the outline of the polishing apparatus 10 will be described with reference to FIGS. 1 and 2. 1 and 2 are diagrams showing a configuration of a polishing apparatus 10 according to the first embodiment. FIG. 1 schematically illustrates a portion of the polishing apparatus 10 that polishes the substrate 20.

  The polishing apparatus 10 is, for example, a CMP apparatus that polishes an interlayer insulating film (not shown) provided on a silicon substrate.

  As shown in FIG. 1, the polishing apparatus 10 includes a platen 100. Here, the “platen 100” is a polishing surface plate that rotates in the polishing process.

  A polishing pad 120 is provided on the platen 100. Details of the configurations of the platen 100 and the polishing pad 120 will be described later.

  A slurry pipe 300 is provided on the polishing pad 120. The slurry pipe 300 supplies the slurry onto the polishing pad 120 in the polishing process.

  The polishing apparatus 10 includes a polishing head 200. The polishing head 200 attracts the substrate 20 to the polishing head 200 in the polishing process. In this process, the polishing head 200 presses the substrate 20 onto the polishing pad 120 and polishes the substrate 20 while rotating.

  In addition, the polishing apparatus 10 includes a load lock (not shown) for preparing the substrate 20, a robot (not shown) for transporting the substrate 20, a control unit (not shown) for controlling the polishing apparatus 10, and the like. .

  Next, the configuration of the platen 100 and the polishing pad 120 in the polishing apparatus 10 will be described with reference to FIG. FIG. 2A shows a plan view of the back surface of the polishing pad 120. On the other hand, FIG.2 (b) has shown the sectional view on the AA 'line of Fig.2 (a).

  As shown in FIG. 2A, the polishing pad 120 is provided with a groove 122 that extends to the outer end face on the back surface opposite to the one surface that contacts the substrate 20 to be polished. The groove 122 allows the organic gas generated from the adhesive layer 160 to escape.

  Here, the state where the groove 122 extends “to the outer peripheral end face” means that the opening of the groove 122 is exposed at the outer peripheral end face of the polishing pad 120. Organic gas can escape from here.

  Further, the groove 122 is continuous from the center to the outer peripheral end face. As a result, the organic gas can escape to the outside without stagnation.

  Further, the groove 122 is provided symmetrically with respect to the center of the polishing pad 120 in plan view. Thereby, the board | substrate 20 can be pressed uniformly in a grinding | polishing process.

  In the first embodiment, the grooves 122 are provided radially. Thereby, the organic gas generated from the vicinity of the center of the adhesive layer 160 in a plan view can be efficiently released to the outside of the polishing pad 120.

  The interval between the groove portions 122 is preferably 10 mm or more and 50 mm or less in a portion where the polishing head 200 passes over the polishing pad 120. For example, when the substrate 20 has a diameter of 6 inches, it is 3 inches from the center side of the polishing pad 120 to 3 inches from the center side of the polishing pad 120 on the basis of the position at a distance of half the radius from the center of the polishing pad 120. It is preferable that the interval of the groove 122 to the position is within the above range. As described above, the gap between the groove portions 122 is formed in the above range in the portion where the polishing head 200 passes over the polishing pad 120, so that the gas can be efficiently released in the portion that generates the most heat.

  The plurality of groove portions 122 may be connected to each other. Thereby, gas can be escaped efficiently.

  Further, the larger the number of grooves 122, the more gas can be released. On the other hand, the greater the number of grooves 122, the lower the rigidity of the polishing pad 120. Therefore, it is preferable to determine the number of grooves 122 based on the polishing pressure in the polishing process.

  As shown in FIG. 2B, a groove 122 is formed in the cross section of the polishing pad 120 so as to be in contact with the adhesive layer 160. Here, for example, a rectangular groove 122 is formed. Among these, the bottom surface of the groove 122 is in contact with the adhesive layer 160. Thereby, the gas generated from the adhesive layer 160 can escape to the groove 122.

  As described above, as long as the bottom surface of the groove 122 is in contact with the adhesive layer 160, the cross-sectional shape of the groove 122 is not limited thereto. In addition to the rectangular shape, for example, a trapezoidal shape, a hexagonal shape, a semicircular shape, or a semielliptical shape may be used.

  Although not shown in FIG. 2B, a groove (not shown) may be provided on the surface side of the polishing pad 120. Thereby, in the polishing process, the slurry introduced between the substrate 20 and the polishing pad 120 can be uniformly distributed in a plan view. Therefore, the uniformity of polishing in the polishing process can be improved.

  Here, as a material of the polishing pad 120, for example, foamed polyurethane or the like is used. In the polishing step, the substrate 20 can be polished with the polishing pad 120.

  Under the polishing pad 120, an adhesive layer 160 for fixing the polishing pad 120 and a cushion layer 140 described later is provided. The adhesive layer 160 includes, for example, natural rubber, acrylic resin, or silicone resin. When the adhesive layer 160 made of such a material is used, an organic gas is generated due to heat generation in the polishing process. For this reason, the effect of this embodiment can be acquired suitably. Note that the adhesive layer 160 is not limited to the above-described material, and when the gas is generated by heat generation, the effect of the present embodiment can be obtained similarly.

  Further, a cushion layer 140 may be provided between the polishing pad 120 and the platen 100 with an adhesive layer 160 interposed therebetween. Thereby, the uniformity of polishing can be improved in the polishing step. Examples of the material of the cushion layer 140 include a fiber nonwoven fabric, a nonwoven fabric in which a fiber nonwoven fabric is impregnated with a polyurethane elastic body, or a rubber elastic sheet.

  Note that a groove (not shown) may be formed on the surface of the cushion layer 140, or the groove may not be formed on the contrary. In the polishing process, the most heat generation occurs on the polishing pad 120 side. For this reason, organic gas tends to be generated in the adhesive layer 160 on the polishing pad 120 side. Therefore, in this embodiment, it is preferable that the groove part 122 is provided at least on the back surface of the polishing pad 120.

  Next, the dimensions of the polishing pad 120 and the groove 122 will be described with reference to FIG. FIG. 3 is an enlarged view of a portion B in FIG.

  In FIG. 3, the thickness a of the polishing pad 120 is, for example, not less than 0.5 mm and not more than 5 mm. Furthermore, when using the above-mentioned cushion layer 140, it is preferable that it is 1 mm or more and 4 mm or less. When the thickness a of the polishing pad 120 is within the above range, the groove 122 can be formed while maintaining the rigidity of the polishing pad 120.

  Moreover, the depth b of the groove part 122 among the polishing pads 120 is 0.3 mm or more and 0.6 mm or less, for example. Note that the depth b of the groove 122 is smaller than the thickness a of the polishing pad 120. When the depth b of the groove 122 is within the above range, the gas from the adhesive layer 160 can be effectively released.

  Here, “the depth b of the groove 122” means the depth at the deepest portion of the groove 122. Therefore, for example, in the case of the semicircular groove 122, it means the depth at the top of the semicircle.

  When a groove (not shown) is also provided on the front surface side of the polishing pad 120, it is preferable not to interfere with the groove 122 on the back surface side. At least a through opening is not formed between the groove portion on the front surface side and the groove portion 122 on the back surface side.

  When the depth of the groove on the surface side of the polishing pad 120 is d, a> b + d. Thereby, a through opening is not formed between the groove portion on the front surface side and the groove portion 122 on the back surface side.

  Moreover, the width c of the groove part 122 is 1.5 mm or more and 3.5 mm or less, for example. When the width c of the groove 122 is within the above range, the gas from the adhesive layer 160 can be effectively released.

  The “width c of the groove 122” here refers to the width of the widest portion of the groove 122. Therefore, for example, in the case of the trapezoidal groove 122, it means the width of the long side of the trapezoid.

  Next, the polishing method according to the first embodiment will be described again using FIG. As described above, the polishing method according to the first embodiment is provided on the platen 100 and the platen 100, and extends from the center to the outer end surface on the back surface on the opposite side to the surface on which the substrate 20 to be polished contacts. A polishing apparatus including a polishing pad 120 including the existing groove 122 and an adhesive layer 160 that fixes the polishing pad 120 and the platen 100 is used. In the polishing process, the polishing surface of the substrate 20 is brought into contact with the polishing pad 120 for polishing. Details will be described below.

  First, the substrate 20 to be polished is prepared. The substrate 20 is a silicon substrate provided with an interlayer insulating film (not shown) and Cu wiring (not shown) grown by plating, for example, by a damascene method. In order to polish the substrate 20, the substrate 20 is prepared in a load lock (not shown).

  Next, as shown in FIG. 1, the platen 100 on which the polishing pad 120 is placed is rotated. Next, the slurry is dropped onto the polishing pad 120 from the slurry pipe 300. In this state, while waiting for the substrate 20 to be conveyed, the concentration of the slurry on the polishing pad 120 is stabilized.

  Next, the substrate 20 is transferred from the load lock to the polishing head 200 by a transfer robot (not shown). Next, the substrate 20 is attracted to the polishing head 200.

  Next, the polishing surface of the substrate 20 is brought into contact with the polishing pad 120 for polishing. At this time, the polishing head 200 having the substrate 20 adsorbed is rotated and pressed against the rotated polishing pad 120 with a desired polishing pressure to perform polishing (polishing step). By rotating the platen 100 on which the polishing pad 120 is placed together with the polishing head 200, polishing can be performed uniformly.

  Here, due to heat generation, an organic gas is generated from the adhesive layer 160 to which the polishing pad 120 is attached. In the present embodiment, a groove 122 extending from the center to the outer peripheral end surface is provided on the back surface of the polishing pad 120. Thereby, the gas from the adhesion layer 160 can escape from the groove part 122 outside.

  As described above, the polishing method according to the first embodiment is performed.

  Next, the effects of the first embodiment will be described in comparison with a comparative example.

  First, as a comparative example, consider a case where the groove 122 is not provided on the back surface of the polishing pad 120. Here, in the polishing process, the vicinity of the surface of the polishing pad 120 generates heat from about 40 ° C. to about 60 ° C. due to friction caused by polishing. For this reason, organic gas is generated from the adhesive layer 160. In the case of the comparative example, this gas generates bubbles at the interface between the polishing pad 120 and the adhesive layer 160.

  When such bubbles are generated, there is a possibility that the substrate 20 to be polished floats from the polishing pad 120. Therefore, the contact between the substrate 20 and the polishing pad 120 becomes unstable, and defects such as polishing abnormality and substrate cracking occur.

  On the other hand, according to the first embodiment, the back surface of the polishing pad 120 is provided with the groove 122 extending to the outer peripheral end surface. As a result, even if organic gas is generated from the adhesive layer 160 due to heat generation in the polishing process, it can escape from the groove 122. For this reason, it is possible to suppress the generation of bubbles at the interface between the polishing pad 120 and the adhesive layer 160.

  As described above, according to the first embodiment, the flatness of the polishing pad can be maintained in the polishing process.

(Second Embodiment)
FIG. 4 is a plan view of the back surface of the polishing pad 120 according to the second embodiment. The second embodiment is the same as the first embodiment except that at least a part of the grooves 122 are provided concentrically. Details will be described below.

  As shown in FIG. 4, at least some of the grooves 122 are provided radially and concentrically. Thereby, the path | route of the gas emitted from the adhesion layer 160 can be increased.

  The concentric grooves 122 are provided at the same interval from the center, for example. Moreover, it is provided with the same width. Thereby, the polishing head 200 can press uniformly.

  Furthermore, in addition to the concentric grooves 122, radial grooves 122 may also be provided.

  On the other hand, for example, in the portion where the polishing head 200 passes over the polishing pad 120, the interval between the concentric grooves 122 may be formed narrow. As a result, gas can be efficiently released in the portion that generates the most heat.

  According to the second embodiment, an effect similar to that of the first embodiment can be obtained. Furthermore, according to the second embodiment, concentric grooves 122 are provided in addition to the radial shapes. Thereby, the path | route of the gas emitted from the adhesion layer 160 can be increased. Further, since the groove 122 is provided in parallel with the rotation direction of the polishing pad 120, the generated gas can be easily released to the rear of the rotation.

(Third embodiment)
FIG. 5 is a plan view of the back surface of the polishing pad 120 according to the third embodiment. The third embodiment is the same as the first embodiment except that the groove 122 is provided in a spiral shape. Details will be described below.

  As shown in FIG. 5, the groove 122 is provided in a spiral shape. In this case, the term “spiral” means, in other words, a spiral shape in a plan view. Alternatively, “spiral” refers to a curve that turns away from the center and moves away. In this case, it is preferable that the extending direction of the groove 122 when the center is the base point is opposite to the rotation direction of the platen 100. Thereby, the generated gas can escape to the rear of the rotation using inertia.

  Further, the groove 122 at the center of the polishing pad 120 may be a “circle” having the same center as the polishing pad 120 in plan view. For example, the circular groove 122 preferably has a radius of 30 mm or less. Since the circular groove 122 is provided in the above range, the spiral groove 122 is not mixed in the center.

  According to the third embodiment, the same effect as that of the first embodiment can be obtained. Furthermore, according to the third embodiment, the groove 122 is provided in a spiral shape. Thereby, the generated gas can escape to the rear of the rotation using inertia.

(Fourth embodiment)
FIG. 6 is a plan view of the back surface of the polishing pad 120 according to the fourth embodiment. The fourth embodiment is the same as the first embodiment except that the grooves 122 are provided in a lattice shape. Details will be described below.

  As shown in FIG. 6, the grooves 122 are provided in a lattice shape. The interval between the lattice-shaped grooves 122 is, for example, 10 mm or more and 50 mm or less.

  The polishing pad 120 having the lattice-like groove 122 as described above can be formed by the following method, for example. First, in order to form the polishing pad 120, one large polyurethane mother roll is prepared. Next, a lattice-like groove 122 is formed on the back side opposite to the polishing surface of the mother roll. Next, the mother roll is punched into the size of the polishing pad 120. As described above, the polishing pad 120 of the fourth embodiment can be obtained.

  In the shapes of the first to third embodiments, the center-symmetric groove 122 cannot be processed unless the center of the polishing pad 120 is determined. On the other hand, according to the fourth embodiment, mass production can be easily performed as in the above method.

  According to the fourth embodiment, the same effect as that of the first embodiment can be obtained. Furthermore, according to the fourth embodiment, it is possible to easily manufacture the polishing pad 120 having the lattice-like grooves 122 as described above.

  In addition, although the case where the cushion layer 140 was provided was demonstrated in the above embodiment, the cushion layer 140 does not need to be provided. In this case, the polishing pad 120 is provided on the platen 100 via the adhesive layer 160.

  In the above embodiment, the case where the depth and the width of the groove 122 are uniform has been described. However, the groove 122 is formed with a different depth or width depending on the position of the polishing pad 120 in plan view. May be.

  In addition, the shape of the groove 122 may be a shape in which the shapes of the first to fourth embodiments are mixed.

  As mentioned above, although embodiment of this invention was described with reference to drawings, these are the illustrations of this invention, Various structures other than the above are also employable.

DESCRIPTION OF SYMBOLS 10 Polishing apparatus 20 Substrate 100 Platen 120 Polishing pad 122 Groove part 140 Cushion layer 160 Adhesive layer 200 Polishing head 300 Slurry piping

Claims (13)

The platen,
A polishing pad provided on the platen and provided with a groove extending to the outer peripheral end surface on the back surface opposite to the one surface in contact with the substrate to be polished;
An adhesive layer for fixing the polishing pad and the platen;
A polishing apparatus comprising: The polishing apparatus according to claim 1, wherein
The said groove | channel part is a grinding | polishing apparatus provided center-symmetrically by planar view with respect to the center of the said polishing pad. The polishing apparatus according to claim 1 or 2,
The said groove | channel part is a grinding | polishing apparatus provided radially. In the polishing device according to any one of claims 1 to 3,
At least a part of the groove is a polishing device provided concentrically. The polishing apparatus according to claim 1 or 2,
The groove portion is a polishing apparatus provided in a spiral shape. The polishing apparatus according to claim 1 or 2,
The groove part is a polishing apparatus provided in a lattice shape. In the polishing apparatus according to any one of claims 1 to 6,
The pressure-sensitive adhesive layer is a polishing apparatus including natural rubber, acrylic resin, or silicone resin. In the polishing apparatus according to any one of claims 1 to 7,
A polishing apparatus comprising a cushion layer provided between the polishing pad and the platen via the adhesive layer. In the polishing apparatus according to any one of claims 1 to 8,
The depth of the said groove part is a grinding | polishing apparatus which is 0.3 mm or more and 0.6 mm or less. In the polishing apparatus according to any one of claims 1 to 9,
The width | variety of the said groove part is a grinding | polishing apparatus which is 1.5 mm or more and 3.5 mm or less. In the polishing apparatus according to any one of claims 1 to 10,
The polishing apparatus, wherein the polishing pad has a thickness of 0.5 mm to 5 mm. The platen,
A polishing pad provided on the platen and provided with a groove extending to the outer peripheral end surface on the back surface opposite to the one surface in contact with the substrate to be polished;
An adhesive layer for fixing the polishing pad and the platen;
Using a polishing apparatus comprising
A polishing method in which a polishing surface of the substrate is brought into contact with and polished on the polishing pad. A polishing pad for polishing a substrate,
A polishing pad comprising a groove extending to the outer peripheral end surface on the back surface opposite to the one surface that contacts the substrate to be polished.

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