JP4140644B2 - Pad dressing apparatus and pad dressing method - Google Patents

Description

  The present invention relates to a pad dresser, a pad dressing method, and a polishing apparatus, and more particularly to a pad dresser that regenerates a polishing pad surface of a polishing apparatus that polishes a workpiece such as a semiconductor wafer, a pad dressing method, and a polishing apparatus including the same.

  As semiconductor devices are miniaturized and multilayered, CMP (Chemical Mechanical Polishing) technology has become an indispensable technology indispensable for semiconductor device manufacturing processes. This CMP technique is used not only for planarization of interlayer insulating films but also for various processes such as Cu wiring and element isolation.

  One of the important specifications in planarization CMP is the uniformity of the polishing rate within the work surface (polishing uniformity). In order to improve the polishing uniformity, it is important to uniformly distribute the factors affecting the polishing rate within the work surface.

  The important factors include the polishing pressure and the relative speed of polishing. The important factors that have not been quantified are the surface condition of the polishing pad. A preferred surface condition of the polishing pad is formed by pad dressing. This is because, for example, in so-called in-situ dressing in which pad dressing is simultaneously performed during polishing, strict control of the surface condition of the polishing pad is important due to the fact that the polishing rate drops sharply when the pad dressing is stopped. It is clear.

  Pad dressing is a slurry in which a pad dresser (hereinafter sometimes simply referred to as a dresser) with a grindstone such as diamond is brought into contact with the polishing pad and the surface of the polishing pad is scraped or roughened. This means that the holding ability is initialized to a state where the polishing is possible, or the holding ability of the slurry is restored to the polishing pad in use to maintain the polishing ability.

  As this pad dresser, a dresser in which diamond abrasive grains are electrodeposited is conventionally used, and many are used to dress the polishing pad by being pressed around the polishing pad while being rotated around an axis (for example, (See Patent Document 1 or Patent Document 2.)

  FIG. 12 is a conceptual diagram for explaining the pad dresser described in Patent Document 1. In FIG. As shown in FIG. 12, the pad dresser 130 described in Patent Document 1 has a substrate 131 on which diamond abrasive grains 133, 133,.

  FIG. 13 is a conceptual diagram for explaining the pad dresser described in Patent Document 2. As shown in FIG. 13, in principle, the pad dresser 130A described in Patent Document 2 has a so-called gimbal structure in which a substrate 131A on which diamond abrasive grains 133, 133,. Thus, it is attached to the support portion 132A so as to be swingable in all directions, and has a structure that follows the surface of the polishing pad 20.

  Moreover, what provided the brush dresser other than the diamond dresser is also known (for example, refer patent document 3). This Patent Document 3 discloses a diamond dresser that is a first dresser that scrapes off the surface of the polishing pad, and a brush dresser that is a second dresser for scraping out foreign substances clogged in the recesses of the polishing surface of the polishing pad. .

  Since the brush dresser is intended to scrape out foreign substances clogged in the recesses of the polishing surface, the diamond dresser, which is the first dresser, is responsible for the so-called pad dressing, which is used to scrape the pad.

  A nylon brush is used as a member used as a brush dresser. However, the nylon brush has the ability to brush the pad surface, but has no effect of scraping the pad surface.

  Therefore, in this disclosed technique, there is no content of scraping the pad surface with a brush and performing dressing, and it is used only as a means for removing foreign substances staying on the pad surface.

In addition, there are those that describe dressing using a brush (for example, see Patent Document 2 or Patent Document 4 above). However, the brush dressers described in Patent Document 2 and Patent Document 4 are also described as a brushing method for scraping out foreign matter in the polishing pad, as in Patent Document 3, and are not dressings for scraping the surface of the polishing pad.
JP 2001-274122 A JP 2003-181756 A Japanese Patent Laid-Open No. 2003-212355 Japanese Patent Laid-Open No. 10-329003

  Incidentally, the polishing pad used in the CMP apparatus has uneven thickness of the polishing pad itself and uneven adhesion to the polishing surface plate, and therefore the surface of the polishing pad after application is not flat. The surface of the polishing pad after pasting usually has a height difference of about 30 μm to 50 μm.

  However, in CMP, in order to uniformly polish the wafer surface, it is required to dress the polishing pad surface having such undulations uniformly along the surface.

  FIG. 11 shows the concept of pad dressing specifications required for CMP. As shown in FIG. 11, for example, when dressing a polishing pad 20 in which waviness with a height difference of about 50 μm is formed with a width of about 100 mm, it is required to dress uniformly according to the waviness. Thus, since the polishing pad is made of an elastic material, the pad dressing in the CMP apparatus can be positioned as a surface reference grinding process of the elastic material.

  However, in the pad dresser 130 described in Patent Document 1 described above, since the dresser is completely fixed to the support portion 132, only the crest portion of the polishing pad surface waviness is scraped off. Therefore, there is a problem that uniform dressing along the surface of the polishing pad cannot be performed.

  Further, the pad dresser 130A described in Patent Document 2 is supported such that the dresser surface follows the polishing pad surface, but cannot be uniformly dressed following the polishing pad surface in actual pad dressing. . This is because the pad dresser tilts with respect to the polishing pad 20 because a large frictional force acts on the surface of the pad dresser that contacts the polishing pad 20 that moves at high speed. When the friction is reduced by tilting, the pad dresser returns to the original posture, and as a result, the polishing pad 20 is intermittently contacted (stick-slip).

  Such a variation (non-uniformity) in dressing within the polishing pad surface causes the following problems with respect to the polishing performance on the wafer. First, a portion that is not dressed and a portion that is not dressed in the polishing pad surface are mixed, so that uneven polishing (polishing variation) occurs in the wafer surface. Next, in the step of starting up the polishing pad, the entire surface is not uniformly dressed and the dressing area gradually expands, so that it takes time for the polishing rate to be saturated. Those whose polishing rate does not saturate cannot be used for product processing, resulting in a long pad startup time.

  Furthermore, when dressing the polishing pad using a conventional diamond electrodeposition plate, as described above, when the polishing pad moves at a high speed, the pad dresser tilts due to frictional force and then returns to the original posture. As a result, the entire pad dresser system repeats intermittent contact. This phenomenon causes the aforementioned dressing variation in the circumferential direction of the polishing pad, but the problem is not limited to this.

  As for the size of the pad chips to be removed by dressing, when the pad dresser makes intermittent contact, a portion that can be sharply shaved and a portion that can be shaved small are mixed, resulting in a large variation in the size of the chips. Further, the polishing pad surface is not stably and finely scraped, but as a result, it is greatly peeled off and scraped, so that the amount of wear of the polishing pad worn by dressing becomes large. As a result, there is a problem that the life of the pad is shortened and the replacement cycle of the pad is accelerated. For this reason, the conventional pad dresser has an essential problem in structure from the viewpoint of surface-based grinding of the elastic body.

  Further, prior to the present invention, the present inventor has studied to determine the effect of pad dressing. First, without removing the polishing pad surface, the polishing pad surface was brushed with a nylon brush while supplying pure water, and the recovery of the polishing rate in the clogged polishing pad was evaluated. However, despite the supply of pure water and brushing for a long time, the polishing rate recovered only 31.4% at most. At this time, the surface of the polishing pad was observed by SEM and it was confirmed that the foreign material on the surface of the polishing pad had been removed cleanly (related documents: Daichi Kamikawa, Takashi Fujita et al., 2004 Tohoku Branch Academic Lecture Meeting) (See p.22).

  From this experiment, it is clarified that pad dressing is not performed only by removing foreign substances staying on the surface of the polishing pad by brushing. After that, it was confirmed that the polishing rate was recovered by performing a normal diamond dressing process for scraping the polishing pad surface, and it is necessary to scrape the polishing pad surface to perform pad dressing.

  In addition to this, it has also been clarified that the surface of the polishing pad is chemically modified in the process of decreasing the polishing rate due to clogging of the polishing pad. In addition, it has been confirmed that the polishing rate is partially recovered by scraping different kinds of materials. This phenomenon is not only due to the fact that the decrease in the polishing rate is caused simply by the accumulation of foreign matter on the pore portion of the polishing pad, but also because the chemical properties of the polishing pad surface itself are greatly affected. (Related literature: Takashi Fujita et al., P. 845, Proceedings of the 2005 JSPE Spring Conference)

  For this reason, the present inventor has the effect that the foreign matter on the surface of the polishing pad is scraped off is insufficient as a dressing for maintaining the polishing rate, and it is essential to scrape the modified pad surface. Was revealed.

  Dressing in the sense of cutting the surface of the polishing pad is performed using a dressing plate on which diamond, which is the first dresser, is electrodeposited as described above.

  From the above, it has become clear that it is indispensable to perform pad dressing in scraping the polishing pad surface following the polishing pad surface, that is, by finely grinding the polishing pad.

  However, simply polishing the surface of the polishing pad is not sufficient. It is indispensable to roughen the surface of the polishing pad while shaving, for example, in the case of a canna, and when cutting without roughening, the retention of the slurry is deteriorated and the dressing is performed. Don't be. In dressing, it is important to scrape the surface while forming the fine roughness necessary to improve or maintain the retention of the slurry against the pad.

  By the micro removal of the polishing pad surface and the formation of micro roughness by such dressing, the modified portion of the polishing pad surface is effectively removed, and the substantial surface area for holding the slurry is increased on the polishing pad surface. It is possible to ensure a sufficient polishing rate.

  In the formation of microroughness, the processing target is a resin material made of a polymer called a polishing pad, and because it is a material having many bubbles on the surface. This is very different from grinding. When grinding porous resin material with abrasive grains, pay careful attention to the design, such as the size of the abrasive grains and the shape of the tip of the abrasive grains, so that the abrasive grains do not clearly bite into the material. I need to pay.

  By the way, in conventional pad dressing, dressing is performed by pressing a plate electrodeposited with diamond against a polishing pad. As a result, the surface of the polishing pad was scraped off while the diamond on the plate moved, but under low pressure conditions, the diamond electrodeposited on the plate could not obtain a sufficient depth of cut for the pad. The dressing was performed by pressing the plate with a large pressure. For this reason, the surface of the polishing pad is roughened while being shaved, but as a result, the surface of the polishing pad is excessively shaved to shorten the life of the polishing pad.

  Further, prior to carrying out the present invention, the present inventors roughened the surface of the polishing pad using a tool in which diamond was first electrodeposited on a fine needle tip. As a result, it was confirmed that the surface was scraped off very efficiently, and it was confirmed by SEM observation that the polishing pad surface was finely and effectively roughened even though it was a porous resin material.

  However, as described above, in the dresser using the conventional dressing plate, the contact force is intermittent and the dressing plate is tilted by the frictional force between the polishing pad and the dresser, and the friction is reduced by the tilting to return to the original posture. The dressing is done.

  There are also actual research reports on this intermittent contact (Ara philipossian, Zhonglin Li, Hyosang Lee, Len Borucki, Ryozo Kimura, Naoki Rikita and Kenji Nagasawa, Effect of Diamond Disc Conditioner Design and Kinematics on Process Hydrodynamics during Copper CMP, Proceedings of See CMP-MIC conference (2005) p.43 and TPMerchanr, JNZabasajja, LJBorucki, A. Scott Lawing, A Pad Wear Model For CMP Process Optimization, Proceedings of CMP-MIC Conference (2005) p.143-150. ).

  In this report, it is mentioned that when the vertical load applied to the dresser is small, the dresser loses the frictional force and tilts against the pad and tilts. In consideration of this, we perform motion analysis of the dressing plate.

  The present inventor also performed pad dressing under a flexible joint mechanism using a dressing plate which is a conventional technique. At this time, in order to evaluate the uniformity of the dressing, a paint was applied to the surface of the polishing pad, and the uniformity of the dressing was evaluated based on the degree of removal of the paint.

  As a result, as shown in FIG. 9, in the conventional dressing mechanism, it is apparent that the surface of the polishing pad is obviously non-uniformly dressed. This reveals that the polishing pad is not evenly polished due to the influence of unevenness of the thickness and sticking of the polishing pad in addition to the above-mentioned dresser being in intermittent contact with the pad. ing.

In view of such circumstances, the present invention has been made in light of the background based on such many verifications. When dressing a polishing pad of a polishing apparatus such as a CMP apparatus, the surface of the polishing pad is uniform. An object of the present invention is to provide a pad dressing apparatus and a pad dressing method provided with a pad dresser capable of achieving dressing, shortening the startup time of the polishing pad, a stable and high polishing rate, and extending the life of the polishing pad.

In order to achieve the above object, the present invention provides a table, a polishing pad fixedly supported on the table and formed of a polyurethane material, a wafer carrier for holding a workpiece, and the polishing. pad dressing apparatus comprising: a pad dresser the surface of the pad dressing process, wherein the pad dresser is to have a plurality of tip roughening cutting the pad surface at all times in contact with the surface of the polishing pad, said plurality of A plurality of elastic members having a flexible length with which the front end portion of the elastic member contacts the polishing pad with a constant pressure, and a base end portion of the elastic member are supported and fixedly supported so as to be substantially parallel to the table. Each of the elastic members and the support portion of the pad dresser moves relative to the table. There is contact with the polishing pad independently, the elastic member is pressed against the surface of the polishing pad the tip at a predetermined pad dressing pressure by elastic deformation, the pressed elastic member said polishing pad It comprises a pad dresser configured to cut and roughen the surface and to dress the polishing pad uniformly along the shape of the surface of the polishing pad.

  According to the first aspect of the present invention, the tip of the elastic member is brought into contact with the polishing pad, the elastic member is elastically deformed to generate the dressing pressure, and the tip of the elastic member is dressed. Following the surface, uniform pad dressing along the surface of the polishing pad can be performed.

According to a second aspect of the present invention, the elastic member is composed of a collection of brush-like materials formed of a metal material, and the vicinity of the tip of the brush-like material is coated with a wear-resistant member. and that it, or, the present invention is as claimed in claim 3, Sentanko formed by wear-resistant material is fixed to the distal end portion of the elastic member, the destination terminal, diamond, diamond-like carbon The tungsten carbide is preferably formed of any one of tungsten carbide.

  According to this, it is possible to efficiently dress the polishing pad with a brush-like material formed of a metal material whose tip is coated with a wear-resistant member or a tip terminal formed of a high-hardness wear-resistant material. it can.

Further, according to a fourth aspect of the present invention, the elastic member may be a thin plate shape, and a plurality of the tip terminals may be fixed to the tip portion. In addition, it is preferable that the distal end portion of the elastic member is formed of an assembly of linear bodies in which a plurality of notches are formed toward the proximal end portion, and the distal end portion is separated into a plurality of portions.

  According to the fifth aspect of the present invention, the plurality of tip terminals are fixed to the tip of the elastic member, and the tip of the elastic member is separated into a plurality of parts. Even if a slipping intermittent contact phenomenon appears, the dressing action is always performed as a whole, and uniform pad dressing along the polishing pad surface is possible.

Further, the present invention is as claimed in claim 6, preferably the destination terminal is fixed to the distal end portion of each of the previous SL plurality of linear bodies.

According to the invention of claim 6 , the elastic member is composed of an assembly of a plurality of linear bodies, and the tip terminal is fixed to the tip of each linear body. Even if a stick-slip intermittent contact phenomenon appears at the tip terminal of the solid body, as a whole, an efficient dressing operation is always performed, and uniform pad dressing along the surface of the polishing pad can be performed.

The invention according to claim 7 is the invention according to any one of claims 1, 2, 3, 4, 5, or 6, wherein the support portion is moved toward and away from the polishing pad. Thus, a pad dresser is provided in which pressure adjusting means for adjusting the pad dressing pressure is provided by adjusting the amount of bending of each of the elastic members.

According to the invention of claim 7, since the pressure adjusting means for adjusting the pad dressing pressure by adjusting the deflection amount of each elastic member is provided, the pad dressing can be performed under the optimum conditions.

The invention according to claim 8 is the invention according to claim 7, wherein the support portion is parallel to the first support body for fixing the base end portion of the elastic member and the polishing pad of the elastic member. A second support body that regulates a position in a plane and is attached to the first support body so as to be movable toward and away from the first support body, and the second support body with respect to the first support body. The pad dresser is characterized by adjusting the effective flexible length of each of the elastic members and adjusting the pad dressing pressure.

According to the invention of claim 8, since the effective flexible length of each elastic member is configured to be adjustable, the pressure adjustment of the pad dressing can be easily performed.

As described above, according to the pad dressing apparatus and the pad dressing method of the present invention, uniform pad dressing along the polishing pad surface is possible, and good processing with excellent in-plane uniformity of the polishing rate is performed. Can do.

Preferred embodiments of a pad dressing apparatus and a pad dressing method according to the present invention will be described below in detail with reference to the accompanying drawings. In each figure, the same number or symbol is attached to the same member.

  FIG. 1 is a perspective view showing a polishing apparatus according to an embodiment of the present invention. The polishing apparatus 10 shown in the figure is mainly composed of a polishing surface plate 12, a wafer carrier 14, and a pad dresser 30.

  The polishing surface plate 12 rotates in the direction of arrow A in the figure by driving a motor 18 connected to the rotating shaft 16. The wafer carrier 14 holding a wafer as a workpiece is driven by a motor (not shown) connected to the rotation shaft 22A and rotates in the direction of arrow B. A polishing pad 20 is affixed to the upper surface of the polishing surface plate 12, and slurry is supplied onto the polishing pad 20 from a slurry supply nozzle (not shown).

  The pad dresser 30 is pressed against the surface of the rotating polishing pad 20 to perform dressing for eliminating clogging of the polishing pad 20, restoring the retention of the slurry, and maintaining the polishing ability.

  FIG. 2 is a conceptual diagram showing the first embodiment of the pad dresser 30 of the present invention. The pad dresser 30 mainly includes an elastic member 31 and a support portion 32 that supports the base end portion 31 a of the elastic member 31. The support portion 32 is supported by a pressure adjusting means 34 that moves toward and away from the polishing pad 20.

  As the elastic member 31, an assembly (for example, a brush-like assembly) of stainless steel, duralumin, brass, or a linear metal material having a high elastic modulus and high hardness and wear resistance is preferably used.

  Each tip 31b of the elastic member 31 is preferably formed in a sharp shape and is covered with a high-hardness wear-resistant material.

  The high-hardness wear-resistant material may be diamond abrasive grains, DCL (Diamond Like Carbon), cemented carbide, etc., and the fixing method may be CVD (Chemical Vapor Deposition) or coating in addition to plating such as electrodeposition. A method or the like can also be used.

  As shown in FIG. 2 (a), the support portion 32 is a method of sandwiching the base end portion 31a of the elastic member 31 with two members, a method of holding by adhesion, or a method of holding as shown in FIG. 2 (b). Various fixing methods, such as a method of providing a fixing hole in the support portion 32 and implanting several pieces at a time, can be employed. The pressure adjusting means 34 can be constituted by a guide member (not shown) and a screw member driven by a motor, but other driving mechanisms can also be used.

  FIG. 7 shows a schematic diagram of dressing by the pad dresser 30 of the present invention. The Young's modulus of the elastic member 31 is E, the effective flexible length of the elastic member 31 is L, the thickness of the elastic member 31 is t, the width of the elastic member 31 is b, and the coefficient of friction between the elastic member 31 and the polishing pad 20 Is μ, and the horizontal displacement due to the bending of the elastic member 31 is δ, the dressing pressure is expressed by the following equation (1).

例えば、研磨パッド２０表面のうねりが±５０μｍとしたとき、ヤング率Ｅ＝１０１Ｇｐａ、厚みｔ＝０．４ｍｍ、幅ｂ＝０．３ｍｍ、有効長さＬ＝３０ｍｍの特性を有する弾性部材３１を使用すると、ドレッシング圧力Ｐ＝２０±０．０７６ｇｆとなり、研磨パッド２０の高さバラツキによる圧力ばらつきは、０．４%以下程度である。

For example, when the waviness of the surface of the polishing pad 20 is ± 50 μm, the elastic member 31 having the characteristics of Young's modulus E = 101 Gpa, thickness t = 0.4 mm, width b = 0.3 mm, and effective length L = 30 mm is used. Then, the dressing pressure P becomes 20 ± 0.076 gf, and the pressure variation due to the height variation of the polishing pad 20 is about 0.4% or less.

  Further, in addition to the followability of the elastic member 31 to the surface of the polishing pad 20, if the abrasive grains supported by the elastic member 31 are displaced and moved independently of each other, the average is always stable. Thus, it acts on the polishing pad 20.

  In FIG. 2, when dressing the polishing pad 20, a predetermined amount of the support portion 32 is brought close to the polishing pad 20 from the state in which the tip terminal 33 of the pad dresser 30 is in contact with the surface of the rotating polishing pad 20. The elastic member 31 is bent. As the elastic member 31 is elastically deformed in this way, a dressing pressure is created, and the surface of the polishing pad 20 is dressed. As described above, the optimum dressing pressure can be obtained by adjusting the amount of bending of the elastic member 31 by the pressure adjusting means 34.

  Further, the tip terminal 33 follows the height difference due to the undulation of the surface of the polishing pad 20 and the stress fluctuation value corresponding to the change in the amount of deflection of the elastic member 31 due to the tracking is small. And uniform dressing.

  Further, since each elastic member 31 is formed as an independent assembly, even if the distal end portion 31b of each elastic member 31 is intermittently brought into contact with the polishing pad 20 in a stick-slip manner, a plurality of elastic members 31 are provided. As a whole assembly of the members 31, 31,..., The tip portions 31b, 31b,... Of any of the plurality of elastic members 31, 31,. A uniform pad dressing along is possible.

  As shown in FIG. 1, the pad dresser 30 is fixed to the rotary shaft 25 and attached to the arm 26 provided with the moving mechanism 27, and reciprocally moves between the central portion and the peripheral portion of the polishing pad 20, or elastically. By arranging the members 31 in a state of being aligned in the radial direction of the polishing pad 20 and performing pad dressing while reciprocating in the radial direction of the polishing pad 20 by the moving mechanism 27, the uniformity of the dressing in the polishing pad surface can be improved. .

  FIG. 3 is a conceptual diagram showing a second embodiment of the pad dresser 30 of the present invention. The pad dresser 30A mainly includes an elastic member 31A and a support portion 32 that supports the base end portion 31a of the elastic member 31A. A tip terminal 33 is fixed to the tip 31b of the elastic member 31A. The support portion 32 is supported by a pressure adjusting means 34 that moves toward and away from the polishing pad 20.

  As the elastic member 31A, a leaf spring, a piano wire or the like is preferably used. Further, the tip terminal 33 fixed to the tip 31b of the elastic member 31A is preferably a high-hardness wear-resistant material, and diamond abrasive grains, DCL, carbide or the like is fixed by a method such as electrodeposition, CVD, coating, or the like. The

  FIG. 4 is a conceptual perspective view showing a third embodiment of the pad dresser 30 of the present invention. The pad dresser 30B according to the third embodiment uses a thin plate spring 31B as the elastic member 31A.

  A plurality of notches 31d, 31d,... Are formed on the leaf spring 31B from the distal end portion 31b toward the proximal end portion 31a, and the distal end portion 31b is separated into a plurality of portions. Further, tip terminals 33, 33,... Made of diamond abrasive grains are electrodeposited on the tips of the separated parts.

  As described above, the high-hardness and wear-resistant material can use DCL, carbide, etc. in addition to diamond abrasive grains, and the fixing method can be CVD, coating or the like in addition to plating such as electrodeposition. You can also.

  As shown in FIG. 4, the pad dresser 30 </ b> B is configured to dress the surface of the polishing pad 20 by causing a dressing pressure to be generated at the tip terminals 33, 33,.

  As shown in FIG. 4, the leaf spring 31B is separated into a plurality of parts from the vicinity of the base end part 31a to the tip part 31b by a plurality of notches 31d, 31d,. Even if the contact is intermittently brought into contact with the polishing pad 20 in a stick-slip manner, the tip springs 33, 33,... A uniform pad dressing along the surface of the pad 20 is performed.

  FIG. 5 is a conceptual diagram showing a fourth embodiment of the pad dresser 30 of the present invention. In the pad dresser 30C according to the second embodiment, an aggregate (for example, a brush-like aggregate) of piano wires 31C, 31C,...

  The base end portion 31a of the piano wire 31C as each linear body is fixed to the support portion 32, and a tip terminal 33 made of diamond abrasive grains is electrodeposited on the tip end portion 31b. Each tip terminal 33 contacts the polishing pad 20 in a state where each piano wire 31C is elastically deformed as shown in FIG. 5, so that an appropriate dressing pressure can be obtained.

  Since the elastic member 31 is formed of an aggregate of independent piano wires 31C, the tip terminals 33, 33,... Of each piano wire 31C are also connected to the polishing pad 20 in this fourth embodiment. Even if they are intermittently contacted in a stick-slip manner, as a whole assembly of the plurality of piano wires 31C, 31C,..., The terminal terminals 33, 33,. The pad is in contact with the polishing pad 20, and uniform pad dressing along the surface of the polishing pad 20 is performed.

  In the fourth embodiment, the piano wire 31C is used as the linear body. However, the present invention is not limited to this, and other materials may be used as long as the linear body has a high elastic modulus such as glass fiber or resin. Can be used. Further, in the case of a material such as glass fiber or resin, it is difficult to electrodeposit the tip terminal 33. In the case of such a material, the tip terminal 33 is fixed by bonding or the like.

  FIG. 6 is a conceptual diagram showing a fifth embodiment of the pad dresser 30 of the present invention. In the pad dresser 30D according to the fourth embodiment, the support portion 32 is divided into a first support body 32A and a second support body 32B.

  The first support 32A is a member that fixes the base end portion 31a of each of the plurality of elastic members 31, 31,..., And the second support 32B is a plurality of holes that are formed in the horizontal position of each elastic member 31. Is regulated. The second support 32B is supported by a plurality of adjustment screws 32C, 32C,... So as to be able to approach or separate from the first support 32A, and the effective flexible length L of the elastic member 31 can be finely adjusted. It is like that.

  Since the pad dresser 30D of the fifth embodiment is formed as described above, the effective flexible length L of the elastic member 31 can be easily adjusted, and the dressing pressure P can be easily finely adjusted.

  The elastic member 31 in the fifth embodiment is the elastic member 31 shown in FIGS. 2A and 2B, the elastic member 31A shown in FIG. 3, and the elastic member 31B shown in FIG. Any of the elastic members 31C shown in FIG. 5 can be preferably used.

  FIG. 8 shows a pad pretreatment apparatus for dressing the polishing pad 20 and initializing the polishing pad 20 to a polishable surface state. The pad pretreatment device 40 includes a rotary table 41 that rotates while holding the polishing pad 20, a pad dresser 30, a water or slurry supply device (not shown), and the like.

  The rotary table 41 has a suction hole for sucking and fixing the polishing pad 20 and is rotated by a motor (not shown). Also, the pad dresser 30 described above is provided, and the polishing pad 20 and the pad dresser 30 are brought into contact with each other while rotating, so that the surface of the polishing pad 20 is finely scraped to roughen the surface of the polishing pad 20. In order to make the surface of the polishing pad 20 fine and rough, it may be performed while supplying water to the polishing pad 20.

  As a dressing condition, for example, a foamed polyurethane pad is used as the polishing pad 20 and is fixed to the rotary table 41 by vacuum suction. The polishing pad 20 is rotated at 30 rpm, the pad dresser 30 is rotated at 80 rpm, and the surface roughness Ra is 0.4 μm to 0.6 μm.

  Thus, since the pad pretreatment device 40 includes the pad dresser 30 described above, uniform pad dressing can be performed, and the surface state of the polishing pad 20 can be initialized to a state where polishing can be performed in a short time. Can do.

  Examples of the pad dresser 30 according to the first embodiment of the present invention will be described below. First, the pad dresser 30 has 500 elastic members 31 made of SUS304, a diameter of 0.3 mm, an effective length of 20 mm, a Young's modulus of 193 GPa, and the tip portion 31b without any abrasive grains and being rounded. The outer diameter was fixed to the support portion 32 having a size of about 100 mm × 60 mm.

  This pad dresser 30 is used for dressing of a polishing pad (foamed polyurethane pad, IC1000 (XY Groove Type single layer) manufactured by NITHAHAS) of a polishing apparatus (ChaMP232: manufactured by Tokyo Seimitsu Co., Ltd.). A 6-in oxide film wafer (P-TEOS) is used as the polishing sample, and SS25 (manufactured by Cabot), which is a fumed silica slurry, is used as the slurry. Polishing is performed under conditions of a polishing time of 1 min, a polishing pressure of 4 psi, and a platen rotation speed of 80 rpm. The dressing condition is an interval dress, and the polishing process interval is 1 min.

  For comparison, a conventional plate type dresser was also tested. In the use of a conventional dresser, the plate diameter is 4 inches, the abrasive grains are diamond abrasive grains # 100, and the load condition is 29.4 N. The dressing condition is the rotational scanning method.

  Under these conditions, the polishing pad was first dressed with the present invention and a conventional plate-type dresser, and the size of the chips on the polishing pad was confirmed.

  As a result of the confirmation, as shown in FIG. 14, in the conventional plate-type dresser, the average value is 30.7 μm and the standard deviation is 10.5 μm. In the present invention, the average value was 20.8 μm and the standard deviation was 7.1 μm, and the present invention gave finer chips with smaller variation.

  From this result, it was confirmed that the polishing pad itself was finely scraped by the dressing method of the present invention, rather than the work of scraping off the by-product on the surface of the polishing pad as shown in conventional nylon brushes. It was confirmed that the size was very fine compared with the conventional plate-type dresser, and the variation was small. This is because the individual cutting edges are constantly dressing in contact with the polishing pad at a constant pressure. For comparison, when the polishing pad was brushed with a nylon brush, similar fine chips were not observed.

  Next, the startup speed of the polishing pad of the conventional plate type pad dresser and the pad dresser of the present invention was compared. As a result of the comparison, as shown in FIG. 15, the conventional plate type dresser uses about 15 sheets (15 min) until the polishing rate is stabilized. In the pad dresser of the present invention, a predetermined polishing rate of 2500 A / min is reached in four sheets (4 min) after startup.

  Subsequently, the dressing variation in the polishing pad surface was compared. As shown in FIG. 16, as a result of evaluating the variation in dressing using a dyed polishing pad, the dressing material of the present invention clearly removes the dyeing material uniformly in the polishing pad surface and is uniformly dressed. I can confirm that.

  Furthermore, polishing shapes were compared in the polishing pad startup process. As shown in FIG. 17, the conventional plate-type pad dresser has a noticeable variation in polishing in the radial direction within the wafer surface, whereas the pad dresser of the present invention has a small variation in the radial direction. As a result, it was confirmed that polishing variation was reduced by uniform dressing.

  Next, the Example by 2nd Embodiment of the pad dresser 30 concerning this invention is shown. As the support portion 32, a disk made of SUS304 and having a diameter of 150 mm was used. The elastic member 31A was made of a material SUS304, a diameter of 0.3 mm, and an effective length of 10 mm, and diamond abrasive grains (grain size # 60) were electrodeposited as a tip 33 at the tip. About 15000 elastic members 31A electrodeposited with the diamond abrasive grains were fixed in the disk surface of the support portion 32.

  Using this pad dresser 30A, a polishing pad made of polyurethane foam whose surface was dyed was dressed. Dressing conditions were such that the number of rotations of the polishing pad 20 was 30 rpm, the number of rotations of the pad dresser 30A was 80 rpm, and the surface roughness Ra was 0.4 μm to 0.6 μm.

  FIG. 9 shows the result of this pad dressing, and it can be seen that the dressing is uniformly applied over the entire surface of the polishing pad 20 as compared with a conventional pad dresser that makes intermittent contact.

  Further, pad polishing was performed (in-situ dressing) while polishing the dummy wafer with the polishing apparatus 10 using the pad dresser 30A, and the polishing pad 20 was started up.

  FIG. 10 is a graph showing a comparison between start-up by the conventional pad dresser and start-up by the pad dresser 30A of the present invention. In FIG. 10, the horizontal axis represents the number of wafers, and the vertical axis represents the polishing rate (Å / min). Further, the startup curve by the conventional pad dresser is shown by a dotted line, and the startup curve by the pad dresser 30A of the present invention is shown by a solid line. According to this, the start-up time by the pad dresser 30A of the present invention is shortened to about 1/3 of the start-up time by the conventional pad dresser.

  In addition, when performing pad dressing, more effective pad dressing can be performed by providing a slurry supply nozzle so as to supply slurry along the elastic member 31A (plate spring 31B, piano wire 31C), Is preferred.

As described above, according to the pad dressing apparatus and the pad dressing method of the present invention, the dressing pressure is generated by the elastic deformation of the elastic member 31, so that the dressing can be performed following the swell of the polishing pad 20 surface. It is possible to perform uniform pad dressing along the surface of the polishing pad 20.

  Further, by making the elastic members 31 individually independent, even if the individual members intermittently come into contact with the polishing pad 20 in a stick-slip manner, any one of the plurality of members is always used for dressing as the entire elastic member 31. Because of this, uniform dressing can be applied over the entire surface of the polishing pad 20.

  Further, according to the polishing apparatus 10 of the present invention, since the pad dresser capable of uniform pad dressing along the surface of the polishing pad is provided, the polishing rate is excellent in work surface uniformity. Processing can be performed.

The perspective view showing the polish device concerning an embodiment of the invention. The conceptual diagram showing 1st Embodiment of the pad dresser of this invention. The conceptual diagram showing 2nd Embodiment of the pad dresser of this invention. The conceptual diagram showing 3rd Embodiment of the pad dresser of this invention. The conceptual diagram showing 4th Embodiment of the pad dresser of this invention. The conceptual diagram showing 5th Embodiment of the pad dresser of this invention. The dressing schematic diagram of the pad dresser of this invention. The front view showing the pad pre-processing apparatus concerning embodiment of this invention. The comparison figure which shows the uniformity of pad dressing. The graph which compares the starting time of a polishing pad. Explanatory drawing showing the concept of the pad dressing requested | required of CMP. The conceptual diagram showing the structure of the conventional pad dresser. The conceptual diagram showing the structure of another conventional pad dresser. The graph which shows the size of the chip of pad dressing. The graph which compares the starting time of a polishing pad. The comparison figure which compared about the dispersion | variation in the dressing in a polishing pad surface. The graph which compares the grinding | polishing shape in the polishing pad starting process.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Polishing apparatus, 20 ... Polishing pad, 30 * 30A * 30B * 30C ... Pad dresser, 31 ... elastic member, 31B ... leaf spring (elastic member), 31C ... piano wire (linear body, elastic member), 31a ... base end part, 31b ... tip part, 31d ... notch, 32 ... support part, 32A ... first 1 support, 32B ... second support, 33 ... tip terminal, 34 ... pressure adjusting means, 40 ... pad pretreatment device, 41 ... rotary table, L ... effective flexible length

Claims (11)

Table,
A polishing pad fixedly supported on the table and formed of a polyurethane material ;
Pad dressing apparatus having the surface before Symbol polishing pad and the pad dresser to grinding treatment, and
The pad dresser is always brought into contact with the surface of the polishing pad have a plurality of tip roughening cutting the pad surface, having a flexible length of the distal end portion of said plurality of contacting the polishing pad at a constant pressure A plurality of elastic members;
A support portion that supports a base end portion of the elastic member and is fixedly supported so as to be substantially parallel to the table;
The tip of the pad dresser moves relative to the table, and the tip of each elastic member is brought into contact with the polishing pad independently, and the elastic member is elastically deformed to cause the tip. The portion is pressed against the surface of the polishing pad with a predetermined pad dressing pressure, and the pressed elastic member scrapes and roughens the surface of the polishing pad, and dresses the polishing pad uniformly along the shape of the surface of the polishing pad. A pad dressing apparatus comprising a pad dresser configured to perform the above. The pad dressing device according to claim 1, wherein the elastic member is composed of an assembly of brush-like materials formed of a metal material. A tip terminal formed of a wear-resistant material is fixed to the tip of the elastic member,
The pad dressing apparatus according to claim 1, wherein the tip terminal is formed of any one of diamond, diamond-like carbon, and tungsten carbide. The pad dressing device according to claim 1 or 3, wherein the elastic member has a thin plate shape, and a plurality of the tip terminals are fixed to a tip portion. 5. The front end portion of the elastic member has a plurality of cutouts toward a base end portion, and the front end portion is composed of an assembly of linear bodies separated into a plurality of portions. A pad dressing device according to claim 1 . The pad dressing device according to claim 5, wherein the tip terminal is fixed to a tip portion of each of the plurality of linear bodies. 2. The pressure adjusting means for adjusting a pad dressing pressure by adjusting the amount of flexure of each of the elastic members by moving the support portion toward and away from the polishing pad. The pad dressing device according to any one of 2, 3, 4, 5, or 6. The support portion regulates a position of the elastic member in a plane parallel to the polishing pad and a first support body that fixes a base end portion of the elastic member, and the first support body. A second support attached so as to be movable toward and away from it,
Adjusting the effective flexible length of each of the elastic members and adjusting the pad dressing pressure by adjusting the second support in contact with and away from the first support. The pad dressing apparatus according to claim 7. And tables, is fixedly supported on the table, a polishing pad formed of polyurethane material, the pad dresser for dressing a surface of a pre-Symbol polishing pad, the pad dressing method according to the pad dressing apparatus equipped with the pad dresser the constant contact with the surface of the polishing pad have a plurality of tip roughening cutting the pad surface, a plurality of elastic members having a flexible length of the distal end portion of said plurality of contacting the polishing pad at a constant pressure And a support portion that supports a base end portion of the elastic member and is fixed and supported so as to be substantially parallel to the table, and the support portion of the pad dresser is relative to the table. to tip of each of the elastic member with the moving independently in contact with the polishing pad, the elastic member child is elastically deformed The tip is pressed against the surface of the polishing pad at a predetermined pad dressing pressure, together with the pressing has been the elastic member roughening grinding the polishing pad surface, uniformly the polishing along the shape of the surface of the polishing pad by A pad dressing method comprising polishing the workpiece with the polishing pad on which pad dressing has been performed. Relative movement of the polishing pad and the pad dresser while bringing the pad dresser into contact with the polishing pad;
The pad dressing method according to claim 9 , wherein the pad dressing is performed while supplying pure water or slurry. The support portion regulates a position of the elastic member in a plane parallel to the polishing pad and a first support body that fixes a base end portion of the elastic member, and the first support body. A second support attached so as to be movable toward and away from it,
The pad dressing pressure is adjusted by adjusting the effective flexible length of the elastic member by adjusting the second support to move away from the first support. The pad dressing method according to claim 9 or claim 10 .

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