JP2009148867A - Grinding pad, its manufacturing method, grinding device, and grinding method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a grinding pad which can eliminate problems such as scratching during a grinding process, and at the same time can extend the replacing cycle thereof, and to provide a grinding pad manufacturing method, a grinding device, and a grinding method. <P>SOLUTION: The grinding pad 110a has a base layer 111, and a grinding layer 112 which is arranged on the base layer 111 and to which a grinding liquid is fed. The grinding layer 112 has first grooves 112a formed in a first surface (upper surface) opposite to the base layer 111 and second grooves 112b formed in a second surface (lower surface) of the base layer 111 side and appearing when the first layer is worn by a predetermined quantity. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a polishing pad for polishing a polishing object using a polishing liquid, a method for manufacturing the same, a polishing apparatus including the polishing pad, and a polishing method.

  In recent years, with the further miniaturization of semiconductor devices, it has been required to planarize the surface of a wafer (semiconductor substrate) on which an insulating film or a conductor film is formed with high accuracy. In order to satisfy such requirements, CMP (Chemical Mechanical Polishing) apparatuses are widely used at present. The CMP apparatus is used in various processes for manufacturing a semiconductor device, such as polishing a silicon wafer serving as a substrate, forming a wiring by a damascene method, and planarizing an insulating film. The CMP apparatus is also used for manufacturing a hard disk (magnetic recording device), manufacturing an MCM (multichip module: hybrid integrated circuit), and polishing a lens.

  FIG. 1 is a diagram showing an outline of a CMP apparatus used for manufacturing a semiconductor device. As shown in FIG. 1, the CMP apparatus includes a platen (polishing surface plate) 10, a polishing head 14, a slurry supply nozzle 15, and a conditioning disk 12.

  The platen 10 is fixed to the rotary shaft 10a and rotates with the rotation of the rotary shaft 10a. A polishing pad 11 is mounted on the platen 10. As the polishing pad 11, a material made of a foamable resin such as foamed polyurethane is often used.

  The polishing head 14 is disposed above the platen 10. The polishing head 14 sucks and holds the wafer 13 on the lower surface side. The polishing head 14 is fixed to the rotary shaft 14a and rotates with the rotation of the rotary shaft 14a.

  A conditioning disk 12 is also disposed above the platen 10. The conditioning disk 12 is fixed to the rotary shaft 12a and rotates with the rotation of the rotary shaft 12a. The conditioning disk 12 is used to keep the surface of the polishing pad 11 in an optimal state (conditioned state) for polishing. The conditioning disk 12 is also called a conditioner or dresser, and is usually made of a diamond grindstone.

  The slurry supply nozzle 15 is connected to a slurry supply device (not shown) via a tube 15 a, and slurry (polishing liquid) 16 is dropped from the slurry supply nozzle 15 onto the polishing pad 11.

  The slurry 16 dropped on the polishing pad 11 is supplied between the polishing pad 11 and the wafer 13 by the rotation of the platen 10. Then, the surface of the wafer 13 is mechanically and chemically polished by the polishing agent (polishing particles) and the chemical solution contained in the polishing pad 11 and the slurry 16.

  2A is a plan view showing an example of a polishing pad of the CMP apparatus shown in FIG. 1, and FIG. 2B is a cross-sectional view showing a portion of the polishing pad taken along the line I-I.

  As shown in FIG. 2A, a plurality of grooves 11 a are concentrically provided on the upper surface (polishing surface) of the polishing pad 11. Further, as shown in FIG. 2B, the cross section of the groove 11a of the polishing pad 11 is rectangular. Such a groove 11a uniformly supplies the slurry 16 dripped onto a predetermined region on the pad 11 (for example, the central region of the pad 11 in the CMP apparatus shown in FIG. 1) to the entire pad 11, or The slurry 16 is held so that the slurry 16 is interposed between the wafer 11 and the wafer 13, the polishing scraps composed of the components of the wafer 13 and the pad 11 generated by the polishing process, and the abrasive particles of the aggregated slurry 16 For example, it has various functions such as discharging foreign matter from the pad 11 and the wafer 13 together with the extra slurry 16.

The following patent documents 1 to 4 disclose techniques related to the structure of the groove of the polishing pad.
JP 2006-167908 A JP 2000-354952 A JP 2001-54856 A JP 2006-187819 A

  By the way, if the polishing process of the wafer 13 is continued in the CMP apparatus, the upper surface of the polishing pad 11 may be clogged with foreign matters such as polishing dust. Therefore, it is necessary to periodically perform a process (conditioning process) of scraping the upper surface of the pad 11 using the conditioning disk 12 shown in FIG. 1 so that the upper surface of the pad 11 is in an optimum state for polishing. It becomes.

  However, by performing the conditioning process, the polishing pad 11 is worn, and the groove 11a of the pad 11 becomes shallow accordingly. As the groove 11a becomes shallower, the in-plane uniformity of the polishing rate with respect to the wafer 13 is deteriorated, and foreign matter is hardly discharged from the groove 11a, and the foreign matter remaining in the groove 11a causes polishing scratches (scratches) on the wafer 13. Problems occur. Therefore, it is preferable to replace the pad 11 before such a problem in the polishing process occurs.

  The period for exchanging the polishing pad 11 is often defined by the number of processing sheets that are empirically expected to cause no problems in the polishing process, based on the past occurrence of problems.

  However, since the wear rate of the polishing pad 11 varies depending on the type of members constituting the CMP apparatus, the type of the object to be polished, the conditions of the polishing process and the conditioning process, the number of processed wafers 13 defined as described above is reached. Even if not reached, the groove 11a may be shallow to a level where problems in the polishing process occur, and problems such as scratches may occur.

  On the other hand, at the manufacturing site, since the time required for replacing the polishing pad 11 (and the process confirmation performed after the pad 11 replacement) is relatively long, the pad 11 must be replaced in order not to reduce the operating rate of the CMP apparatus. There is a demand to make the cycle as long as possible.

  The present invention provides a polishing pad, a method for manufacturing the polishing pad, a polishing apparatus, and a polishing method that can make the replacement period of the polishing pad longer than before while avoiding the occurrence of problems in the polishing process such as generation of scratches. For the purpose.

  According to one aspect of the present invention, a base layer and a polishing layer provided on the base layer and supplied with a polishing liquid are provided, and the polishing layer is a first side opposite to the base layer. There is provided a polishing pad comprising: a first groove formed on a surface; and a second groove formed on a second surface on the base layer side and appearing when the first surface is worn by a certain amount. The

  According to the present invention, the polishing pad has a laminated structure including the base layer and the polishing layer, and the first groove is formed on the upper surface (first surface) of the polishing layer serving as the upper layer, and the lower side A second groove is formed on this surface (second surface). And when the polishing layer is worn out by a certain amount, the second groove appears on the upper surface of the polishing layer. In other words, in the present invention, having such a first groove and a second groove is substantially the same as that the polishing pad has a deep groove.

  Thereby, the exchange period of a polishing pad can be lengthened. Or it can make it difficult to generate | occur | produce the problem in grinding | polishing processing, such as the generation | occurrence | production of a scratch. That is, it is possible to lengthen the polishing pad replacement period while avoiding such problems.

  In the present invention, the distance between the first surface of the polishing layer and the second groove is preferably smaller than the depth of the first groove. That is, it is preferable to have a structure in which the second groove appears on the upper surface of the polishing layer before the polishing layer is worn and the first groove is completely eliminated.

  In such a structure, it is not necessary to deepen individual grooves (first groove and second groove). If the groove of the polishing pad is simply deepened, the amount of slurry covering the pad surface is reduced, so that the polishing rate is reduced. That is, by making the polishing pad such a structure, it is possible to avoid a decrease in polishing rate due to a decrease in the amount of slurry covering the pad surface.

  According to another aspect of the present invention, a step of preparing a base layer of the polishing pad, a step of preparing a polishing layer of the polishing pad, and a step of forming a first groove on the first surface of the polishing layer And a step of forming a second groove on a second surface of the polishing layer opposite to the first surface, and affixing the second surface of the polishing layer having at least the second groove to the base layer There is provided a method of manufacturing a polishing pad comprising the steps of:

  Furthermore, according to another aspect of the present invention, a polishing head to which an object to be polished is attached, a polishing platen disposed below the polishing head, and a polishing platen provided on the polishing platen, A polishing pad for polishing the attached polishing object; and a polishing liquid supply unit for supplying a polishing liquid to the surface of the polishing pad, wherein the polishing pad is a base layer provided on the polishing surface plate And a polishing layer provided on the base layer and supplied with a polishing liquid, wherein the polishing layer is formed on a first surface opposite to the base layer, and the first groove, There is provided a polishing apparatus comprising: a second groove formed on the second surface on the base layer side and appearing when the first surface is worn by a certain amount.

  Furthermore, according to another aspect of the present invention, there is provided a polishing method for polishing an object to be polished with a polishing pad in which a base layer and a polishing layer are laminated, wherein the polishing layer is opposite to the base layer. A layer having a first groove formed on the first surface and a second groove formed on the second surface on the base layer side and appearing when the first surface is worn by a certain amount. A polishing method is provided.

  In the present invention, the polishing pad has a laminated structure composed of a base layer and a polishing layer, the first groove is formed on the upper surface of the polishing layer as the upper layer, and the second groove is formed on the lower surface. Grooves are formed. And when the polishing layer is worn out by a certain amount, the second groove appears on the upper surface of the polishing layer.

  Accordingly, it is possible to lengthen the replacement cycle of the polishing pad while avoiding the occurrence of problems in the polishing process such as generation of scratches, and to improve the operating rate of the polishing apparatus.

(1) Description of Preliminary Items Prior to the embodiment of the present invention, preliminary items leading to the present invention will be described.

  In order to lengthen the replacement period of the polishing pad while avoiding the occurrence of problems in the polishing process such as the occurrence of scratches, the inventor of the present application first has a polishing pad having a groove deeper than the conventional polishing pad. Devised.

  FIG. 3 is a cross-sectional view showing the polishing pad of this example and a conventional polishing pad (the polishing pad shown in FIG. 2). In FIG. 3, the structure shown on the left is the polishing pad of this example, and the structure shown on the right is a conventional polishing pad. FIG. 3 shows a state before the polishing pad of this example and the conventional polishing pad are worn out.

  As shown in FIG. 3, the groove 11a of the conventional polishing pad 11 has a rectangular shape with a width of “0.6” when the depth is defined as “1.0” in an arbitrary unit. On the other hand, the groove 21a of the polishing pad 21 of this example has a width of “0.6” when the depth of the groove 11a of the conventional polishing pad 11 is defined as “1.0” in an arbitrary unit. It has a rectangular shape with a depth of “1.3”. Note that the thickness of the pad 21 in this example is the same as that of the conventional pad 11.

  As shown in FIG. 3, in the polishing pads 11 and 21 having the same thickness, the surface position where the problem such as the generation of scratches in the polishing pad 21 of this example occurs (or when such a problem occurs). The surface position of the polishing pad at the assumed groove depth D: the position indicated by the alternate long and short dash line in FIG. 3) is lower than the surface position of the conventional polishing pad 11 by the depth of the groove 21a. The portion E that can be used for the polishing process in the polishing pad 21 in this example is larger than the portion E ′ in the conventional polishing pad 11. For this reason, the polishing pad 21 of this example can increase the number of wafers processed compared to the conventional polishing pad 11, and can increase the pad replacement period.

  On the other hand, in the polishing pad 21 of this example, since the depth of the groove remaining when the same number of processing is polished is larger than that of the conventional polishing pad 11, scratches are generated. It can be said that the margin for the occurrence of this problem can be increased. That is, the pad 21 of this example can make it less likely to cause such a problem than the conventional pad 11.

  However, as shown in FIG. 3, in the polishing pad 21 of this example and the conventional polishing pad 11, when the amount of slurry supplied onto the polishing pad is the same, the liquid of the slurry covering the surface of the polishing pad 21 of this example The surface position (the position indicated by the two-dot chain line in FIG. 3) is lower than the liquid surface position of the conventional polishing pad 11 by an amount corresponding to an increase in the amount of slurry discharged as the groove 21a is deepened. That is, in the pad 21 of this example, the amount of slurry covering the pad surface is smaller than that of the conventional pad 11.

  FIG. 4 is a diagram showing the relationship between the groove depth and the polishing rate in the polishing pad shown in FIG. In FIG. 4, the broken line indicates the amount of slurry supplied on the pad (predetermined amount), and the solid line indicates the minimum amount of slurry supplied to obtain a predetermined polishing rate (hereinafter simply referred to as such amount). "A required amount of slurry supply"), and a one-dot chain line indicates a polishing rate at a predetermined amount.

  As shown in FIG. 4, if the groove of the polishing pad is deepened, the necessary amount of slurry supply also increases.

  On the other hand, the polishing rate increases as the amount of slurry supplied onto the polishing pad increases. However, when the amount of slurry supplied onto the pad exceeds a certain level, the polishing rate does not increase and remains at a predetermined value (hereinafter, this value is referred to as “saturation value”). For this reason, as shown in FIG. 4, at the depth of the pad groove where the required amount of slurry supply is less than the predetermined amount (the depth of the pad groove is smaller than F), the polishing rate is a predetermined amount. Value (saturated value). However, at the pad groove depth at which the required amount of slurry supply is greater than the predetermined amount (the depth of the pad groove is greater than F), the polishing rate cannot maintain a saturation value, The polishing rate decreases as the groove becomes deeper.

  For this reason, in the polishing pad 21 of this example, when the required slurry supply amount becomes larger than a predetermined amount due to the deepening of the groove 21a, there arises a problem that the polishing rate decreases from the saturation value. In the example shown in FIG. 4, although the polishing rate is a saturation value at the depth (“1.0”) of the groove 11a of the conventional polishing pad 11, the depth (“1” of the groove 21a of the polishing pad 21 of this example). .3 "), the polishing rate is reduced by about 10%.

  Therefore, in the polishing pad 21 of this example, in order to return the reduced polishing rate to the saturation value, the amount of slurry supplied onto the pad 21 is increased by the amount corresponding to the decrease in the polishing rate, that is, increased by 10%. It is considered necessary. Considering the allowance, it is considered necessary to increase the amount of slurry supplied onto the pad 21 by the depth of the groove, that is, increase by 30%.

  From this, it can be considered that the problem that the polishing rate decreases when the groove of the polishing pad is deepened is solved by increasing the amount of slurry supplied onto the pad. However, increasing the amount of slurry naturally increases the amount of slurry used in the polishing process and increases the cost. On the other hand, it is conceivable to solve this problem by increasing the polishing time. However, if the polishing time is lengthened, the production efficiency of the product using the object to be polished is lowered, resulting in an increase in cost.

  In view of these problems, the present inventor has come up with an embodiment of the present invention as described below.

(2) Embodiment of the present invention (First embodiment)
FIG. 5 is a diagram showing an outline of the CMP apparatus (polishing apparatus) according to the embodiment of the present invention. As shown in FIG. 5, the CMP apparatus according to the embodiment of the present invention includes a platen (polishing surface plate) 100, a polishing head 140, a slurry supply nozzle 150, and a conditioning disk 120.

  The platen 100 is fixed to the rotation shaft 100a and rotates with the rotation of the rotation shaft 100a. A polishing pad 110 is mounted on the platen 100. Details of the polishing pad 110 will be described later.

  The polishing head 140 is disposed above the platen 100. The polishing head 140 holds the wafer 130 by suction on the lower surface side. The polishing head 140 is fixed to the rotating shaft 140a, and rotates with the rotation of the rotating shaft 140a.

  A conditioning disk 120 is also disposed above the platen 100. The conditioning disk 120 is fixed to the rotating shaft 120a and rotates as the rotating shaft 120a rotates. The conditioning disk 120 is made of a diamond grindstone, and is used to keep the surface of the polishing pad 110 in a conditioned state.

  The slurry supply nozzle 150 is connected to a slurry supply device (not shown) via a tube 150 a, and slurry (polishing liquid) 160 is dropped onto the polishing pad 110 from the slurry supply nozzle 150.

  FIG. 6 is a perspective view of the CMP apparatus. As shown in FIG. 6, a plurality of (three in FIG. 6) platens 100 and one load cup 210 are provided on the base 200. Around each platen 100, there are provided a slurry supply arm 220 provided with a slurry supply nozzle at the tip and a conditioning disk drive arm 230 to which a conditioning disk 120 is attached. A pedestal (not shown) for temporarily holding the wafer before polishing and after polishing is provided inside the load cup 210. The polishing head 140 is attached to the head unit 300 supported by the rotating shaft 300a. In the CMP apparatus shown in FIG. 6, three platens 100 and one load cup 210 are arranged around the rotation shaft 300 a, and the head unit 300 has four polishings corresponding to the platen 100 and the load cup 210. A head 140 is provided. When the head unit 300 rotates while the wafer is sucked and held on the polishing head 140, the wafer is transferred to each platen 100. The rotating shaft 140a of the polishing head 140 is configured to reciprocate in the rotational radius direction of the head unit 300 as indicated by arrows in FIG.

  The configuration of the polishing pad according to the first embodiment of the present invention will be described below.

  FIG. 7 is a cross-sectional view showing a part of the polishing pad according to the first embodiment of the present invention. 7A shows the state of the polishing pad before it is worn out, FIG. 7B shows the state of the worn polishing pad, and FIG. 7C is more than the state shown in FIG. 7B. The state of the worn polishing pad is shown.

  As shown in FIG. 7, the polishing pad 110 a of this embodiment includes a base layer (lower layer) 111 and a polishing layer (upper layer) 112 provided on the base layer 111. 5 and 6, the base layer 111 is bonded onto the platen 100 among the base layer 111 and the polishing layer 112 constituting the polishing pad 110 (110a). The slurry 160 is supplied onto the polishing layer 112. For this reason, the upper surface of the polishing layer 112 becomes the polishing surface. The base layer 111 is made of a resin such as polyurethane, and the polishing layer 112 is made of a foamable resin such as foamable polyurethane. Note that the material forming the base layer 111 and the polishing layer 112 is not limited to resin, and the material forming the base layer 111 and the polishing layer 112 may be other materials such as a fiber material and an inorganic material.

  As shown in FIG. 7A, the polishing layer 112 before being worn has a first groove 112a on an upper surface (a polishing surface or a surface opposite to the base layer 111: also referred to as “first surface”). The second groove 112b is formed on the lower surface (surface on the base layer 111 side: also referred to as “second surface”). A plurality of the first grooves 112a are arranged concentrically in the surface direction of the polishing layer 112 when the polishing pad 110a is viewed from above (see FIG. 2). A plurality of second grooves 112b are arranged concentrically at a distance d1 from the first groove 112a in the surface direction of the polishing layer 112. The first grooves 112a and the second grooves 112b are not limited to the above-described arrangement. For example, a plurality of the first grooves 112a and the second grooves 112b are arranged radially in the surface direction of the polishing layer 112. Other arrangement modes such as one arrangement in a spiral shape may be used.

  Moreover, as shown to Fig.7 (a), the cross section of the 1st groove | channel 112a has a substantially pentagon shape, and is concave on the lower side. The first groove 112a has a depth of “1.3” when the width is defined as “0.6” in an arbitrary unit, and the depth of the substantially rectangular portion on the upper side of the first groove 112a. Is “0.7”, and the depth of the lower substantially triangular portion (or V-shaped portion) is “0.6”. The cross section of the second groove 112b has a substantially pentagonal shape and is convex upward. The second groove 112b has a depth of “1.0” when the width is defined as “0.6” in an arbitrary unit, and the second groove 112b has a substantially rectangular portion on the lower side. The depth is “0.4”, and the depth of the upper substantially triangular portion (or V-shaped portion) is “0.6”. In the present embodiment, the width of the first groove 112a and the second groove 112b is, for example, 450 μm.

  In the polishing pad 110a of the present embodiment, the first groove 112a and the second groove 112b are not limited to the above-described relationship between the width and the depth, and the first groove 112a and the second groove 112b are the other. You may make it the relationship between the width | variety and the magnitude | size of depth.

However, in the polishing pad 110a of the present embodiment, as shown in FIG. 7A, the end portion of the second groove 112b (the upper end portion: the portion surrounded by the thick dotted line in FIG. 7A) B ₁ but the end of the first groove 112a: has a structure that is at a higher position than (lower end portion FIGS. 7 (a) a portion surrounded by a thin dotted line in) a _1. Alternatively, it can be said that the distance (0.7) between the upper surface of the polishing layer 112 and the second groove 112b is smaller than the depth (1.3) of the first groove 112a. That is, the second groove 112b appears on the upper surface of the polishing layer 112 before the polishing layer 112 is worn away by the conditioning process or the like and the first groove 112a becomes shallow and disappears completely.

  Further, in the polishing pad 110a of the present embodiment, the volume of the first groove 112a remaining when the polishing layer 112 is worn and the second groove 112b appears on the upper surface of the polishing layer 112, and the first volume at that time. The sum of the volume of the two grooves 112b is the same as or smaller than the volume of the first groove 112a before the polishing layer 112 is worn.

  Further, the polishing pad 110a of the present embodiment has a structure in which the area of the upper surface of the worn polishing layer 112 is the same as the area of the upper surface of the polishing layer 112 before being worn. In other words, the polishing layer 112 has a structure in which the area on the upper side of the polishing layer 112 is constant while the polishing layer 112 is worn.

  An example of a method for manufacturing the polishing pad 110a of the present embodiment having the above-described structure will be described with reference to FIG.

  First, as shown in FIG. 8A, a disk-shaped member to be the polishing layer 112 is prepared. As such a member, a foamable resin material such as foamed polyurethane is used.

  Next, as shown in FIG. 8B, the first groove 112a is formed by cutting on one surface of the member to be the polishing layer 112. Next, as shown in FIG. 8C, the second groove 112b is formed by cutting on the other surface (the surface opposite to the surface where the first groove 112a is formed) of the member to be the polishing layer 112. In this way, the polishing layer 112 is formed.

  Next, as shown in FIG. 8D, a base layer 111 made of a disk-shaped member is prepared. As such a member, a resin material such as polyurethane is used. Then, the polishing layer 112 in which the first groove 112a and the second groove 112b are formed is bonded on the base layer 111 with the second groove 112b on the lower side. In this way, the polishing pad 110a of this embodiment is completed.

  Note that the order of forming the first groove 112a and the second groove 112b in the member to be the polishing layer 112 may be reversed. When the order of forming the first groove 112a and the second groove 112b is reversed, a member that becomes the polishing layer 112 may be bonded onto the base layer 111 before the first groove 112a is formed on the other surface. Good. Moreover, although the 1st groove | channel 112a and the 2nd groove | channel 112b were formed in the member used as the grinding | polishing layer 112 by cutting, of course, it is not limited only to cutting. For example, the polishing layer 112 may be formed by molding using a mold having the reverse shape of the first groove 112a and the second groove 112b.

  Next, processing related to polishing of the wafer 130 performed in the CMP apparatus according to the present embodiment will be described with reference to FIG. 9 showing an example of the processing flow.

  As a precondition, in the CMP apparatus shown in FIGS. 5 and 6, it is assumed that the polishing pad 110a is mounted on the platen 100 with the base layer 111 facing down. Further, it is assumed that the wafer 130 before polishing is placed on the pedestal (not shown) of the load cup 210. In such a state, in the first step S11, the polishing head 140 is moved above a pedestal (not shown), and the polishing head 140 is driven to attract the wafer 130 to the polishing head 140.

  In step S12, the head unit 300 is rotated to move the wafer 130 above the polishing pad 110a.

  In step S13, the slurry 160 is supplied onto the polishing pad 110a (polishing layer 112) from the tip of the slurry supply arm 220 (slurry supply nozzle 150), and in the next step S14, the platen 100 is rotated.

  In step S15, the polishing head 140 is rotated, and in the next step S16, the polishing head 140 is driven to press the wafer 130 against the polishing pad 110a (polishing layer 112).

  Thus, the slurry 160 supplied onto the polishing pad 110 a is supplied between the polishing pad 110 a and the wafer 130 by the rotation of the platen 100. Then, the surface of the wafer 130 is mechanically and chemically polished by the polishing agent (polishing particles) and the chemical solution contained in the polishing pad 110 and the slurry 160.

  When the polishing of the wafer 130 is completed, the polishing head 140 is driven again to attract the wafer 130 to the polishing head 140. Then, the head unit 300 is rotated to return the wafer 130 to above the load cup 210, the polishing head 140 is driven, the wafer 130 is detached from the polishing head 140, and the wafer 130 is placed on a pedestal (not shown). . In this way, this processing flow is “end”.

  On the other hand, in the CMP apparatus shown in FIGS. 5 and 6, the conditioning process of scraping the upper surface of the polishing pad 110a (polishing layer 112) using the conditioning disk 120 is periodically performed (for example, the polishing of the wafer 130 is completed). When). By performing the conditioning process, the polishing layer 112 of the polishing pad 110a is worn.

  FIG. 10 appears on the upper surface of the polishing layer 112 in the polishing pad 110a of the present embodiment, the number of wafers 130 subjected to the polishing process (the number of processed wafers 130), the necessary slurry supply amount, and the polishing layer 112. It is a figure which shows the relationship with the volume of a groove | channel. In FIG. 10, the broken line indicates the amount (predetermined amount) of the slurry 160 supplied onto the polishing layer 112, the solid line indicates the necessary amount of slurry supply, and the two-dot chain line appears on the upper surface of the polishing layer 112. It shows the volume of the groove.

  In the polishing pad 110a immediately after replacement (the polishing pad 110a before being worn), only the first groove 112a appears on the upper surface of the polishing layer 112. As shown in FIG. 10, the wafer 130 is polished from this state. As the number of wafers 130 processed increases, the number of conditioning processes performed on the polishing pad 110a also increases. As a result, the polishing layer 112 is worn and the first groove 112a becomes shallow. That is, the volume of the groove (first groove 112a) appearing on the upper surface of the polishing layer 112 is reduced. Along with this, the required amount of slurry supply also decreases. For this reason, when the necessary slurry supply amount in the pad 110a before being worn is less than a predetermined amount, the polishing rate is maintained at the saturation value.

  When the number of processed wafers 130 reaches a predetermined value S, in the polishing pad 110a of the present embodiment, before the first groove 112a is completely removed due to wear of the polishing layer 112, the upper surface of the polishing layer 112 is moved to the first surface. Two grooves 112b appear. At this time, the volume of the grooves (the first groove 112a and the second groove 112b) appearing on the upper surface of the polishing layer 112 is temporarily increased, and the necessary amount of slurry supply is temporarily increased accordingly. . However, in the polishing pad 110a of this embodiment, the sum of the volume of the first groove 112a and the volume of the second groove 112b remaining when the second groove 112b appears on the upper surface of the polishing layer 112 is: It has a structure that is the same as or smaller than the volume of the first groove 112a before the polishing layer 112 is worn. For this reason, when the necessary slurry supply amount in the pad 110a before being worn is less than a predetermined amount, the polishing rate remains at the saturation value.

  Thereafter, when the number of processed wafers 130 exceeds a predetermined value S, the first groove 112a and the second groove 112b appear on the upper surface of the polishing layer 112 in the polishing pad 110a, and then the first groove 112 a is completely eliminated, and only the second groove 112 b appears on the upper surface of the polishing layer 112. Even during this period, as the number of processed wafers 130 increases, the volume of the grooves appearing on the upper surface of the polishing layer 112 decreases. Along with this, the required amount of slurry supply also decreases. For this reason, when the necessary slurry supply amount in the pad 110a before being worn is less than a predetermined amount, the polishing rate is maintained at the saturation value.

  On the other hand, the polishing rate is related not only to the amount of slurry supplied onto the polishing pad, but also to the area of the polishing surface of the pad, and the polishing rate is substantially proportional to the area. The polishing pad 110a of the present embodiment has a structure in which the area of the upper surface (polishing surface) of the worn polishing layer 112 is the same as the area of the upper surface (polishing surface) of the polishing layer 112 before being worn. is doing. That is, the area of the upper surface of the polishing layer 112 before wear (the area of the polishing layer 112 shown in FIG. 7A), the second groove 112b on the upper surface of the polishing layer 112 in the worn polishing layer 112. The area of the polishing layer 112 in a state before the appearance of (or only the first groove 112a appears on the upper surface of the polishing layer 112), and the second groove 112b appears on the upper surface of the polishing layer 112. To the area until the first groove 112a disappears (or the state where both the first groove 112a and the second groove 112b appear on the upper surface of the polishing layer 112) (see FIG. 7). (The area of the polishing layer 112 shown in (b)) and the state after the first groove 112a disappears from the upper surface of the polishing layer 112 (or only the second groove 112b is formed on the upper surface of the polishing layer 112). The state of appearance) The area of the layer 112 (the area of the polishing layer 112 shown in to FIG. 7 (c)) has a structure that all the same. For this reason, even if the polishing layer 112 is worn, the polishing rate can be maintained at a constant value (for example, a saturation value). In this structure, the first groove 112a has a V shape that is concave below the polishing layer 112, and the second groove 112b is a V shape that protrudes above the polishing layer 112. This structure can be easily realized.

  As described above, the polishing pad 110a of the present embodiment has a laminated structure including the base layer 111 and the polishing layer 112, and the first groove 112a is formed on the upper surface of the polishing layer 112 serving as the upper layer. The second groove 112b is formed on the lower surface. The second groove 112b appears on the upper surface of the polishing layer 112 when the polishing layer 112 is worn by a certain amount. That is, the polishing pad 110a according to the present embodiment has such a deep groove as the polishing pad 21 shown in FIG. 3 by having the first groove 112a and the second groove 112b. Will be the same. For this reason, the replacement period of the polishing pad 110a of this embodiment can be extended. On the other hand, it can be said that the pad 110a of this embodiment can make it difficult to generate problems in the polishing process such as the generation of scratches. In FIG. 10, R represents the replacement cycle (number of processed sheets) of the polishing pad 110a of this embodiment, and R ′ represents the replacement period (number of processed sheets) of the conventional polishing pad (the conventional polishing pad 11 shown in FIG. 3). Is shown. By using the same amount of slurry supplied to the pad 110a of this embodiment and the conventional pad 11, the number of processed wafers (that is, the polishing pad replacement period) that is assumed not to cause a problem in the polishing process is examined. As a result, it was found that the processing number R of the pads 110a of the present embodiment is about 1.7 times the processing number R ′ of the conventional pads 11.

  Moreover, in the polishing pad 110 a of this embodiment, the base layer 111 is interposed between the polishing layer 112 and the platen 100. Therefore, even if the second groove 112 b appears on the upper surface of the polishing layer 112 and the slurry 160 flows into the second groove 112 b, the slurry 160 does not contact the platen 100. Thereby, corrosion of the platen 100 due to the chemical liquid contained in the slurry 160 can be avoided.

  Further, the polishing pad 110a of the present embodiment has a structure in which the second groove 112b appears on the upper surface of the polishing layer 112 before the polishing layer 112 is worn and the first groove 112a is completely removed. Therefore, the individual grooves (the first groove 112a and the second groove 112b) do not have to be as deep as the groove 21a of the polishing pad 21 shown in FIG. For this reason, it is possible to avoid a decrease in polishing rate due to a decrease in the amount of slurry covering the pad surface.

  Furthermore, in the polishing pad 110a of this embodiment, the sum of the volume of the first groove 112a and the volume of the second groove 112b remaining when the second groove 112b appears on the upper surface of the polishing layer 112 is: The structure that the volume of the first groove 112a before the polishing layer 112 is worn is the same as or smaller than the volume of the first groove 112a, and the area of the upper surface of the worn polishing layer 112 is the upper side of the polishing layer 112 before wearing. It has the same structure as the surface area. By having these structures, the polishing rate can be maintained at a constant value (for example, a saturation value) from when the new polishing pad 110a is used until the worn polishing pad 110a is replaced.

(Second Embodiment)
Hereinafter, a second embodiment of the present invention will be described. The second embodiment differs from the first embodiment in that the groove structure of the polishing pad (polishing layer) is different, and the other configurations are the same as those in the first embodiment. Here, the description of the overlapping parts is omitted.

  FIG. 11 is a sectional view showing a part of a polishing pad according to the second embodiment of the present invention. 11A shows the state of the polishing pad before being worn, FIG. 11B shows the state of the worn polishing pad, and FIG. 11C is more than the state shown in FIG. 11B. The state of the worn polishing pad is shown.

  As shown in FIG. 11, the polishing pad 110 b according to this embodiment includes a base layer 111 and a polishing layer 113 provided on the base layer 111.

  As shown in FIG. 11A, the polishing layer 113 before being worn has a first groove 113a formed on the upper surface and a second groove 113b formed on the lower surface. The second groove 113b is disposed at a distance d2 from the first groove 113a in the surface direction of the polishing layer 113. The cross section of the first groove 113a has a rectangular shape, and the cross section of the second groove 113b has a substantially pentagonal shape and is convex upward.

Further, in the polishing pad 110b of the present embodiment, as shown in FIG. 11A, the end portion of the second groove 113b (upper end portion: the portion surrounded by the thick dotted line in FIG. 11A) B ₂ but the end of the first groove 113a (the lower end portion: 11 (surrounded by a thin dotted line in a) partial) structure that is at a higher position than the a ₂ (or the upper surface of the polishing layer 113 The distance from the second groove 113b is smaller than the depth of the first groove 113a. That is, the second groove 113b appears on the upper surface of the polishing layer 113 before the polishing layer 113 is worn and the first groove 113a is completely removed.

  Further, in the polishing pad 110b of this embodiment, the volume of the first groove 113a remaining when the polishing layer 113 is worn and the second groove 113b appears on the upper surface of the polishing layer 113, and the first volume at that time. The sum of the volume of the two grooves 113b is the same as or smaller than the volume of the first groove 113a before the polishing layer 113 is worn.

  For this reason, in the polishing pad 110b of the present embodiment, as in the polishing pad 110a of the first embodiment, it is possible to increase the replacement period (or to hardly cause problems in the polishing process such as generation of scratches). can do). In addition, it is possible to avoid a decrease in polishing rate due to a decrease in the amount of slurry existing on the pad. Furthermore, corrosion of the platen 100 due to the chemical liquid contained in the slurry 160 can be avoided.

  Further, in the polishing pad 110b of this embodiment, unlike the polishing pad 110a of the first embodiment, a period from when the second groove 113b appears on the upper surface of the polishing layer 113 until the first groove 113a disappears ( Alternatively, during the period in which both the first groove 113a and the second groove 113b appear on the upper surface of the polishing layer 113, the area above the polishing layer 113 changes and the polishing rate changes. However, the polishing rate can be maintained at a constant value (for example, a saturation value) during a period other than the above-described period from when the new polishing pad 110b is used to when the worn polishing pad 110b is replaced. . Since the second groove 113b has a V shape that protrudes above the polishing layer 113, even if the area of the upper surface of the polishing layer 113 changes during the above-described period, the change occurs. It can be relaxed. That is, the change in the polishing rate can be moderated.

(Third embodiment)
Hereinafter, a third embodiment of the present invention will be described. The third embodiment is different from the first embodiment in that the structure of the groove of the polishing pad (polishing layer) is different, and the other configuration is the same as the first embodiment. Here, the description of the overlapping parts is omitted.

  FIG. 12 is a sectional view showing a part of a polishing pad according to the third embodiment of the present invention. 12 (a) shows the state of the polishing pad before it is worn, FIG. 12 (b) shows the state of the worn polishing pad, and FIG. 12 (c) is more than the state shown in FIG. 12 (b). The state of the worn polishing pad is shown.

  As shown in FIG. 12, the polishing pad 110 c according to this embodiment includes a base layer 111 and a polishing layer 114 provided on the base layer 111.

  As shown in FIG. 12A, the polishing layer 114 before being worn has a first groove 114a on the upper surface and a second groove 114b on the lower surface. The second groove 114b is disposed at a distance d3 from the first groove 114a in the surface direction of the polishing layer 114. The cross section of the first groove 114a has a substantially pentagonal shape and is concave on the lower side. The cross section of the second groove 114b has a rectangular shape.

Further, in the polishing pad 110c of the present embodiment, as shown in FIG. 12A, the end of the second groove 114b (upper end: a portion surrounded by a thick dotted line in FIG. 12A) B ₃ but the end of the first groove 114a (the lower end portion: 12 (surrounded by a thin dotted line in a) partial) structure that is at a higher position than the a ₃ (or the upper surface of the polishing layer 114 The distance from the second groove 114b is smaller than the depth of the first groove 114a). That is, the second groove 114b appears on the upper surface of the polishing layer 114 before the polishing layer 114 is worn away and the first groove 114a is completely removed.

  Furthermore, in the polishing pad 110c of this embodiment, the volume of the first groove 114a remaining when the polishing layer 114 is worn and the second groove 114b appears on the upper surface of the polishing layer 114, and the first volume at that time. The sum of the volume of the two grooves 114b is the same as or smaller than the volume of the first groove 114a before the polishing layer 114 is worn.

  For this reason, in the polishing pad 110c of the present embodiment, as in the polishing pad 110a of the first embodiment, it is possible to lengthen the replacement period (or hardly cause problems in the polishing process such as generation of scratches). can do). Further, it is possible to avoid a decrease in polishing rate due to a decrease in the amount of slurry covering the pad surface. Furthermore, corrosion of the platen 100 due to the chemical liquid contained in the slurry 160 can be avoided.

  Further, in the polishing pad 110c of this embodiment, unlike the polishing pad 110a of the first embodiment, a period from when the second groove 114b appears on the upper surface of the polishing layer 114 until the first groove 114a disappears ( Alternatively, during the period in which both the first groove 114a and the second groove 114b appear on the upper surface of the polishing layer 114, the area above the polishing layer 114 changes and the polishing rate changes. However, the polishing rate can be maintained at a constant value (for example, a saturation value) during a period other than the above-described period from when the new polishing pad 110c is used to when the worn polishing pad 110c is replaced. . Since the first groove 114a has a V-shape that is concave below the polishing layer 114, even if the area of the upper surface of the polishing layer 113 changes during the above-described period, the change Can be relaxed. That is, the change in the polishing rate can be moderated.

(Fourth embodiment)
Hereinafter, a fourth embodiment of the present invention will be described. The fourth embodiment is different from the first embodiment in that the configuration of the grooves of the polishing pad (polishing layer) is different, and other configurations are the same as those in the first embodiment. Here, the description of the overlapping parts is omitted.

  FIG. 13 is a sectional view showing a part of a polishing pad according to the fourth embodiment of the present invention. FIG. 13 (a) shows the state of the polishing pad before being worn, FIG. 13 (b) shows the state of the worn polishing pad, and FIG. 13 (c) is more than the state shown in FIG. 13 (b). The state of the worn polishing pad is shown.

  As shown in FIG. 13, the polishing pad 110 d of this embodiment includes a base layer 111 and a polishing layer 115 provided on the base layer 111.

  As shown in FIG. 13A, the polishing layer 115 before being worn has a first groove 115a on the upper surface and a second groove 115b on the lower surface. The second groove 115b is arranged at a distance d4 from the first groove 115a in the surface direction of the polishing layer 115. The cross sections of the first groove 115a and the second groove 115b have a rectangular shape.

Further, in the polishing pad 110d of the present embodiment, as shown in FIG. 13A, the end portion of the second groove 115b (the upper end portion: the portion surrounded by the thick dotted line in FIG. 13A) B ₄ but the end of the first groove 115a (the lower end portion: 13 (a portion surrounded by a thin dotted line in a)) that is at a higher position than the a ₄ structure (or the upper surface of the polishing layer 115 The distance from the second groove 115b is smaller than the depth of the first groove 115a. That is, the second groove 115b appears on the upper surface of the polishing layer 115 before the polishing layer 115 is worn away and the first groove 115a is completely removed.

  Further, in the polishing pad 110d of the present embodiment, the volume of the first groove 115a remaining when the polishing layer 115 is worn and the second groove 115b appears on the upper surface of the polishing layer 115, and the first volume at that time. The sum of the volume of the two grooves 115b is the same as or smaller than the volume of the first groove 115a before the polishing layer 115 is worn.

  For this reason, in the polishing pad 110d of the present embodiment, as in the polishing pad 110a of the first embodiment, the replacement cycle can be lengthened (or problems in the polishing process such as generation of scratches are less likely to occur. can do). Further, it is possible to avoid a decrease in polishing rate due to a decrease in the amount of slurry covering the pad surface. Furthermore, corrosion of the platen 100 due to the chemical liquid contained in the slurry 160 can be avoided.

  Further, in the polishing pad 110d of this embodiment, unlike the polishing pad 110a of the first embodiment, a period from when the second groove 115b appears on the upper surface of the polishing layer 115 to when the first groove 115a disappears ( Alternatively, during the period in which both the first groove 115a and the second groove 115b appear on the upper surface of the polishing layer 115, the area above the polishing layer 115 changes and the polishing rate changes. However, the polishing rate can be maintained at a constant value (for example, a saturation value) during a period other than the above-described period from when the new polishing pad 110d is used to when the worn polishing pad 110d is replaced. . In the polishing pad 110d of this embodiment, the change in the area of the upper surface of the polishing layer 115 in the above-described period is more abrupt than in the polishing pads 110b and 110c of the second and third embodiments. However, in the polishing pad 110d of this embodiment, both the first groove 115a and the second groove 115b have a rectangular shape, so that the polishing pads 110b and 110c (and the first) of the second and third embodiments are used. It can be formed more easily than the polishing pad 110a) of the embodiment.

  Hereinafter, aspects of the present embodiment will be summarized as additional notes.

(Appendix 1) a base layer;
A polishing layer provided on the base layer and supplied with a polishing liquid;
The polishing layer is formed on a first groove formed on the first surface opposite to the base layer and on a second surface on the base layer side, and appears when the first surface is worn by a certain amount. A polishing pad comprising two grooves.

  (Supplementary note 2) The polishing pad according to supplementary note 1, wherein a distance between the first surface and the second groove is smaller than a depth of the first groove.

  (Additional remark 3) The said 2nd groove | channel is spaced apart from the said 1st groove | channel in the surface direction of the said polishing layer, The polishing pad of Additional remark 1 characterized by the above-mentioned.

  (Supplementary Note 4) The sum of the volume of the first groove when the polishing layer is worn and the second groove appears on the first surface and the volume of the second groove at that time are determined by the polishing layer. The polishing pad according to appendix 1, wherein the polishing pad has a volume equal to or less than the volume of the first groove before being worn.

  (Appendix 5) The polishing pad according to appendix 1, wherein an area of the first surface of the worn polishing layer is the same as an area of the first surface of the polishing layer before being worn.

  (Supplementary note 6) The polishing pad according to supplementary note 1, wherein the first groove has a V-shape that is concave on the second surface side.

  (Additional remark 7) The said 2nd groove | channel has the V shape which becomes convex at the said 1st surface side, The polishing pad of Additional remark 1 characterized by the above-mentioned.

  (Supplementary Note 8) The first groove has a V-shape that is concave on the second surface side, and the second groove has a V-shape that is convex on the first surface side. 2. The polishing pad according to appendix 1, which is characterized.

(Appendix 9) A step of preparing a base layer of the polishing pad;
Preparing a polishing layer of the polishing pad;
Forming a first groove on the first surface of the polishing layer;
Forming a second groove on a second surface opposite to the first surface of the polishing layer;
And a step of bonding the second surface of the polishing layer having at least the second groove to the base layer.

  (Supplementary note 10) The polishing pad according to supplementary note 9, wherein in the step of forming the second groove, a distance between the first surface and the second groove is made smaller than a depth of the first groove. Manufacturing method.

  (Appendix 11) In the step of forming the second groove, the second groove is formed away from the first groove in the surface direction of the polishing layer. Method.

(Appendix 12) A polishing head to which an object to be polished is attached;
A polishing surface plate disposed below the polishing head;
A polishing pad provided on the polishing surface plate and polishing a polishing object attached to the polishing head;
A polishing liquid supply unit that supplies a polishing liquid to the surface of the polishing pad;
The polishing pad includes a base layer provided on the polishing surface plate, and a polishing layer provided on the base layer and supplied with a polishing liquid.
The polishing layer is formed on a first groove formed on the first surface opposite to the base layer and on a second surface on the base layer side, and appears when the first surface is worn by a certain amount. A polishing apparatus comprising two grooves.

  (Supplementary note 13) The polishing apparatus according to supplementary note 12, wherein a distance between the first surface and the second groove is smaller than a depth of the first groove.

  (Supplementary note 14) The polishing apparatus according to supplementary note 12, wherein the second groove is disposed apart from the first groove in a surface direction of the polishing layer.

  (Supplementary Note 15) The sum of the volume of the first groove when the polishing layer is worn and the second groove appears on the first surface and the volume of the second groove at that time are determined by the polishing layer The polishing apparatus according to appendix 12, wherein the polishing apparatus has a volume equal to or less than the volume of the first groove before being worn.

  (Supplementary note 16) The polishing apparatus according to supplementary note 12, wherein an area of the first surface of the worn polishing layer is the same as an area of the first surface of the polishing layer before being worn.

(Supplementary note 17) A method for polishing an object to be polished with a polishing pad in which a base layer and a polishing layer are laminated,
The polishing layer is formed in a first groove formed on the first surface opposite to the base layer and a second surface on the base layer side, and appears when the first surface is worn by a certain amount. A polishing method using a layer having a second groove.

It is a figure which shows the outline | summary of the conventional CMP apparatus. FIG. 2A is a plan view showing an example of a conventional polishing pad, and FIG. 2B is a cross-sectional view showing a part of the polishing pad. It is sectional drawing which shows a part of conventional polishing pad and the polishing pad which made the groove | channel deeper than the conventional polishing pad. It is a figure which shows the relationship between the depth of the groove | channel in the polishing pad shown in FIG. 3, and a polishing rate. 1 is a diagram showing an outline of a CMP apparatus (polishing apparatus) according to an embodiment of the present invention. 1 is a perspective view of a CMP apparatus according to an embodiment of the present invention. FIGS. 7A to 7C are cross-sectional views showing a part of the polishing pad according to the first embodiment of the present invention. FIG. 8A to FIG. 8D are views showing an example of the polishing pad according to the first embodiment of the present invention. It is a flowchart which shows an example of the process which concerns on grinding | polishing of the wafer (polishing target object) performed in the CMP apparatus which concerns on embodiment of this invention. In the polishing pad concerning the 1st embodiment of the present invention, it is a figure showing the relation between the number of processed wafers, the required amount of slurry, and the volume of the groove that appears on the upper surface of the polishing layer. FIG. 11A to FIG. 11C are cross-sectional views showing a part of a polishing pad according to the second embodiment of the present invention. FIG. 12A to FIG. 12C are cross-sectional views showing a part of a polishing pad according to the third embodiment of the present invention. FIG. 13A to FIG. 13C are cross-sectional views showing a part of a polishing pad according to the fourth embodiment of the present invention.

Explanation of symbols

10, 100 ... Platen (polishing surface plate),
11, 21, 110 (110a to 110d) ... polishing pad,
11a, 21a ... groove,
13, 130 ... wafer (object to be polished),
14, 140 ... polishing head,
15, 150 ... Slurry supply nozzle (polishing liquid supply part),
16, 160 ... slurry (polishing liquid),
111 ... Base layer,
112, 113, 114, 115 ... polishing layer,
112a, 113a, 114a, 115a ... first groove,
112b, 113b, 114b, 115b ... second groove.

Claims (8)

The base layer,
A polishing layer provided on the base layer and supplied with a polishing liquid;
The polishing layer is formed on a first groove formed on the first surface opposite to the base layer and on a second surface on the base layer side, and appears when the first surface is worn by a certain amount. A polishing pad comprising two grooves.   The polishing pad according to claim 1, wherein a distance between the first surface and the second groove is smaller than a depth of the first groove.   The polishing pad according to claim 1, wherein the second groove is disposed away from the first groove in a surface direction of the polishing layer.   The sum of the volume of the first groove when the polishing layer is worn and the second groove appears on the first surface and the volume of the second groove at that time are the values before the polishing layer is worn. The polishing pad according to claim 1, wherein the polishing pad is equal to or less than a volume of the first groove.   2. The polishing pad according to claim 1, wherein an area of the first surface of the worn polishing layer is the same as an area of the first surface of the polishing layer before being worn. A step of preparing a base layer of the polishing pad;
Preparing a polishing layer of the polishing pad;
Forming a first groove on the first surface of the polishing layer;
Forming a second groove on a second surface opposite to the first surface of the polishing layer;
And a step of bonding the second surface of the polishing layer having at least the second groove to the base layer. A polishing head to which an object to be polished is attached;
A polishing surface plate disposed below the polishing head;
A polishing pad provided on the polishing surface plate and polishing a polishing object attached to the polishing head;
A polishing liquid supply unit for supplying a polishing liquid to the surface of the polishing pad;
The polishing pad includes a base layer provided on the polishing surface plate, and a polishing layer provided on the base layer and supplied with a polishing liquid.
The polishing layer is formed on a first groove formed on the first surface opposite to the base layer and on a second surface on the base layer side, and appears when the first surface is worn by a certain amount. A polishing apparatus comprising two grooves. A polishing method for polishing an object to be polished with a polishing pad in which a base layer and a polishing layer are laminated,
As the polishing layer, a first groove formed on the first surface opposite to the base layer and a second surface on the base layer side, which appears when the first surface is worn by a certain amount. A polishing method comprising using a layer having two grooves.

Images