KR200357678Y1 - Polishing pad to CMP - Google Patents

Abstract

The present invention relates to a polishing pad for CMP for smoothly polishing the surface of an object including a semiconductor wafer or various substrates, the characteristic configuration of which is a predetermined depth with respect to the polishing surface in the X-axis and Y-axis directions A plurality of first grooves formed across and mutually intersecting; A plurality of second grooves are arranged on the polishing surface at different depths from the first groove, and each end portion in the X-axis and Y-axis directions reaches a predetermined interval in the inward direction from the edge of the polishing surface. According to this configuration, by reducing the elongation of the grooves at the edge of the polishing pad to reduce the detachment of the slurry, which in turn reduces the waste of the slurry, the differentiation of the spacing and depth between the grooves is the target surface of the wafer as the object It has the effect of implementing uniform planarization as a whole.

Description

Polishing pad to chemical mechanical polishing {Polishing pad to CMP}

The present invention relates to a polishing pad for CMP for smoothly polishing the surface of an object including a semiconductor wafer or various substrates.

In general, semiconductor devices, which are in a high integration trend, require precise overlay of each interlayer circuit pattern in response to a reduction in circuit line width. Here, the circuit pattern between each layer is formed by etching a specific portion or depositing or growing a different film material. The surface layer of the circuit pattern obtained therefrom has a curved shape, and the curved shape of the circuit pattern causes alignment errors, including difficulty in forming contacts in the subsequent stacking process of other circuit patterns. Therefore, in the semiconductor device manufacturing process, the wafer requires a process of planarizing the target surface between each unit process.

As described above, a process for planarizing the surface of the wafer includes etch-back or chemical-mechanical polishing (CMP).

Reference will be made here to the CMP process, and the wafer in the semiconductor device manufacturing process will be referred to as the object of the CMP, but the present invention is not limited thereto. The main description is the groove of the polishing pad and the flow of the slurry by the groove. Let's look at the distribution relationship.

A general chemical-mechanical polishing (CMP) process is a process in which the surface of an object is softly reconstituted by chemical reaction and removed by physical force.

As shown in FIG. 1, the polishing pad 10 performing the CMP process is fixedly installed on an upper surface of the surface plate 12 that rotates at a high speed in a horizontal state. On the surface of the polishing pad 10, the continuous supply of the slurry S is made to the rotation center part. At this time, the supplied slurry (S) is distributed in the surface layer of the polishing pad 10 by centrifugal force, and finally goes off from the edge portion. Correspondingly, the wafer W is sucked and fixed to the polishing head 14 so that the target surface is pressed close to the surface of the polishing pad 10 or pressed with a predetermined force, and the high speed rotation is performed between the center and the edge of the polishing pad 10. Move the section of. At this time, the wafer W is kept horizontal with respect to the surface of the polishing pad 10 from the gimbal 16 provided in the polishing head 14.

The main purpose in performing the polishing process for the wafer (W) is to implement the flatness of the surface of the wafer (W) according to the polishing, and the condition for this purpose is to continuously planarize the surface of the polishing pad (10) In addition, a uniform distribution of the slurry S on the surface of the polishing pad 10 is required.

Among the above-described conditions, the method of planarizing the surface of the polishing pad 10 is performed by conditioning the head 18 located from one side of the polishing pad 10 so as to cut the surface layer by driving or periodically driving the process. And the method for uniformly distributing the slurry (S) with respect to the surface of the polishing pad 10, as shown in Figures 1 and 2, the high-speed rotation of the surface plate 12 and thus the polishing pad 10 It is primarily made by the groove G to adjust the flow rate of the slurry S from the difference in the centrifugal force acting on the section between the center of rotation and the edge. In addition, the surface of the polishing pad 10 includes a plurality of pores continuously exposed in the conditioning process or the polishing process. These pores are involved in the uniform distribution of the slurry (S) by allowing the process of receiving and flowing out the slurry (S) flowing by the centrifugal force is made continuously.

As described above, the CMP process is affected by polishing uniformity due to the material properties, surface conditions, and the like of the polishing pad 10 in contact with the surface to be polished of the wafer W. The polishing pad 10 shown in FIG. 2 is a plan view of a polishing pad according to the prior art, in which concentric grooves G having different diameters are formed on the surface of the polishing pad 10 at regular intervals. The slurry supplied to the polishing pad 10 is moved along the groove G by the action of the centrifugal force and supplied to the surface to be polished of the wafer W and the friction surface of the polishing pad 10 to be applied to the wafer W. Polishing will be performed. These grooves G are arranged at a constant width and depth and at regular intervals between each other to influence the supply, discharge and distribution of the slurry.

However, the center portion and the edge portion of the polishing pad 10 corresponding to the to-be-polished surface of the wafer W and the intermediate portion therebetween not only have a difference in physical polishing action due to centrifugal force but also the flow of the slurry S. There are also significant differences for and distributions.

In this regard, when the slurry supplied to the entire surface of the polishing pad 10 is uniformly distributed, the rotation center of the portions of the polishing pad 10 identified above is physically present with respect to the surface to be polished of the wafer W. The acting force is small compared to other parts. The middle portion has a relatively large area in contact with the to-be-polished surface of the wafer W, and the edge portion has a relationship in which centrifugal force is large. Therefore, in order to uniformly polish the to-be-polished surface of the wafer W, it is necessary to efficiently manage the physical action at each part of the polishing pad 10 and the distribution of the slurry thereof.

3 is a registered utility model No. 273586 filed by the applicant of the present invention, the slurry flow for each section of the polishing pad 10 by the concentric grooves (G) in the polishing pad 10 of the prior art and its distribution Due to the difference in density, the edge portion of the wafer W is polished more than the center portion, and it is designed to solve the problem of oversupply of the slurry S.

According to the characteristic configuration, the first groove G1 having an orthogonal shape in the X-axis and Y-axis directions is formed on the polishing surface of the polishing pad 20, and the X-axis and Y are again formed between the first grooves G1. It is formed by forming a second groove G2 perpendicular to the axial direction, that is, parallel to the first groove G1, and having a different depth from the first groove G1.

The present invention secures the above-mentioned Utility Model No. 273586 to more effectively reduce the physical action of the center, middle, and edge of the polishing pad relative to the rotation center of the polishing pad, and the distribution of slurry and waste of slurry. I came to the door.

The present invention aims to balance the ratio of the physical force of each part corresponding to the surface to be polished of the wafer as the object and the distribution ratio of the slurry to each of the parts, that is, the physical and chemical effects of the wafer. The present invention provides a polishing pad of a CMP facility for a semiconductor wafer that enables uniform polishing efficiency on the entire surface.

1 is a cross-sectional view schematically showing the application relationship of the polishing pad from the configuration of a general CMP facility.

FIG. 2 is a plan view illustrating a groove pattern according to the related art formed on an upper surface of the polishing pad illustrated in FIG. 1.

3 is a plan view for explaining the technology disclosed in the Utility Model Registration No. 20-0273586 filed and registered by the present applicant.

Figure 4 is a plan view showing a groove pattern of the polishing pad according to the present invention.

Figure 5 is a plan view showing a polishing pad having a groove pattern of another embodiment according to the present invention.

FIG. 6 is a plan view illustrating a modified embodiment formed by combining the groove patterns of the embodiments of FIGS. 4 and 5.

FIG. 7 is a cross-sectional view showing an example of applying the polishing pad shown in FIGS. 4 to 6 to a sheet type facility.

Explanation of symbols on the main parts of the drawings

10, 20, 30a, 30b, 30c: polishing pad

12: surface plate 14: polishing head

16: gimbal 18: conditioning head

22, 24, 32, 34, 36a, 36b, 36c: groove

A characteristic configuration of the polishing pad of the CMP apparatus for semiconductor wafers according to the present invention for achieving the above object is a plurality of agents forming a shape with a predetermined depth to the polishing surface and cross each other in the X-axis and Y-axis direction With 1 groove; A plurality of second grooves are arranged on the polishing surface at different depths from the first groove, and each end portion in the X-axis and Y-axis directions reaches a predetermined interval in the inward direction from the edge of the polishing surface.

In addition, the first grooves and the second grooves may be formed of equally spaced intervals, and the interval range between each end of the second groove with respect to the edge of the polishing surface is preferably 0.5 to 15 mm. Do.

The interval between the first grooves may be formed at intervals greater than or equal to the second grooves, and the second grooves may form at least two or more arrangements between the first grooves.

On the other hand, the configuration of another embodiment of the present invention for achieving the above object is divided into a grinding surface formed with a plurality of grooves on the center portion and the middle portion around the center portion and the edge portion around the middle portion, Each formation density occupied by the groove is formed more densely in the order of the intermediate portion, the edge portion, and the central portion.

This configuration is divided into a polishing surface formed with a plurality of grooves in the center portion, the middle portion around the center portion and the edge portion around the middle portion, wherein each of the grooves is formed with at least two or more, The spacing between the grooves in each portion is the smallest on the center portion, the edge portion is formed more than the gap on the center portion, the intermediate portion may be formed to be larger than the gap on the edge portion. .

The grooves may be formed of concentric grooves centered on the rotational center of the polishing surface, and the polishing surface on which a plurality of grooves are formed, including the concentric grooves for the respective portions, may be formed on the center portion and the middle portion around the center portion. The groove is divided into an edge portion around the middle portion, and the grooves for the respective portions may be formed deeply in the order of the middle portion, the center portion, and the edge portion.

In addition to the above-described respective configurations, the polishing surface may be formed with at least one through hole so that the slurry is eluted from the bottom.

Hereinafter, the polishing pad of the CMP facility for semiconductor wafer according to each embodiment of the present invention will be described.

Figure 4 is a plan view showing a groove pattern of the polishing pad according to the present invention, Figure 5 is a plan view showing a polishing pad having a groove pattern of another embodiment according to the present invention, Figure 6 is a view of each embodiment of Figures 4 and 5 7 is a plan view showing a modified embodiment formed by combining each groove pattern, and FIG. 7 is a cross-sectional view showing an example of applying the polishing pad shown in FIGS. The same reference numerals are assigned to the same symbols, and detailed description thereof will be omitted.

The polishing pad 30a of the CMP facility for semiconductor wafer according to the present invention, as shown in Fig. 4, starts from reducing the amount of slurry used based on the above-mentioned Utility Model No. 273586. Accordingly, in one embodiment of the polishing pad 30a, the first grooves 32 are formed on the polishing surface at regular intervals in the X and Y-axis directions, and the first grooves 32 are formed between the first grooves 32 again. The second grooves 34 formed at regular intervals in the X-axis and Y-axis directions are formed in parallel with each other.

The first grooves 32 are formed to secure the fluidity of the slurry after slurry or polishing, and cross the edge of the polishing pad 30a from one edge of the polishing surface to the opposite edge with respect to the X-axis and Y-axis directions. To achieve. Further, the depth of these first grooves 32 is 0.5 to 1.0 mm, the width is 0.5 to 0.8 mm, and the space between them is about 5.0 to 8 mm. More preferably, the depth is 0.7 ± 0.05 mm, the width is 0.6-0.65 mm, and the space between them may be 6.35 ± 0.1 mm.

On the other hand, the second groove 34 is for securing the fluidity of the slurry and leading the waste slurry to the first groove 32, the length of which is on the polishing surface of the polishing pad 30a. That is, in each of the directions of the X-axis and the Y-axis, both end portions do not reach at least an edge but are inside thereof. This is to prevent the slurry from being discharged through the ends of the second grooves 34 and to increase the distribution density of the slurry with respect to the edge portion of the polishing pad 30a. Further, the depth of these second grooves 34 is 0.3 to 0.5 mm, the width is 0.1 to 0.3 mm, and the spacing between them may be formed in a size of about 1 to 3 mm. A more preferred embodiment of such a second groove 34 may be made by forming a depth of 0.4 ± 0.05 mm, a width of 0.2 ~ 0.25 mm, the spacing between them is 2.1 ± 0.1 mm. The spacing between them is such that the second grooves 34 form at least two or more arrangements between the first grooves 32 described above. The first grooves 32 and the second grooves 34 form an equally spaced arrangement between neighboring ones.

In this configuration, only the first grooves 32 having a large distance from each other at the edges of the polishing pad 30a and having a deep depth intersect from one edge of the polishing surface to the opposite edge, and the second grooves 34 are polished. It is possible to significantly reduce the discharge amount of the slurry by bringing the slurry flowing close to the edge of the pad 30a to the inner portion thereof.

From this configuration, the slurry supplied to the polishing pad 30a during the polishing process uses the first groove 32 as the main flow passage, and the second groove 34 having a relatively small size (depth and width) as the secondary passage. As a result, the polishing pad 30a is uniformly distributed with respect to the polishing surface. At the points where the first and second grooves 32 and 34 intersect each other, the fluidity of the slurry is complementary to each other, and the indiscriminate discharge of the slurry at the edge of the polishing pad 30a in which the centrifugal force is relatively large By reducing it is possible to reduce the supply of slurry to compensate for this.

On the other hand, the structure of the polishing pad 30b shown in FIG. 5 is for controlling the fluidity of the slurry with respect to the rotation center part C, the intermediate part M, and the edge part E of the polishing pad 30b. Based. That is, the center position C based on the rotation center of the polishing pad 30b is to improve the chemical reaction efficiency due to the slurry while having a weak physical action on the wafer W as an object. . In addition, it is to smoothly supply the slurry to the intermediate portion (M) having a high physical contact frequency with respect to the surface to be polished of the wafer (W).

In this way, the groove in the center portion C has a concentric circular groove 36a formed with a different diameter and at least two or more numbers based on the rotation center of the polishing pad 30b in the middle portion M. Compared with the formed concentric groove 36b, a dense arrangement is achieved, and the depth thereof is deeper than that of the intermediate portion M, and is formed the same or shallower than that of the edge portion E. FIG.

In addition, the intermediate portion M adjacent to the outer periphery of the polishing pad 30b along the outer circumference C has a high contact frequency with the surface to be polished of the wafer W as an object, and thus has a high contact frequency. To prevent abrasion intensification compared to the edge (E) and to improve the fluidity of the slurry by physical action according to the contact frequency, but to reduce the chemical reaction in inverse proportion to the relatively high level of physical action. It is in sake.

In this way, the groove in the middle portion M has a concentric circular groove 36b formed with a different diameter and at least two or more numbers based on the rotational center of the polishing pad 30b and the center portion C. It is formed wider than the gap between the concentric grooves 36a and 36c formed at the edge portion E, and the depth of the concentric grooves 36a and 36c formed at the central portion C and the edge portion E is It forms the shallowest compared with the depth which has.

In addition, the edge portion E neighboring in the outward direction from the intermediate portion M described above has a contact frequency with respect to the circular wafer W as compared with the intermediate portion M as well as at the central portion C. Although at a low level (relative frequency of contact at the wafer W is high), the physical action on the target wafer W is greater than the central portion C and the middle portion M. As a result, the edge portion E has a smaller wear rate than the middle or center portion, but the fluidity of the slurry is higher due to the greater centrifugal force. In order to compensate for this, it is possible to reduce the physical action on the wafer (W) of the corresponding position, to increase the chemical reaction by the slurry, and to prevent the escape of the slurry. The configuration for this is to form concentric grooves 36c of different diameters relative to the center of rotation of the polishing pad 30b, which are equal to or larger than that of the central portion C, and compare them to those at the intermediate portion M. Preferably, the spacing is formed relatively densely. In addition, the depth of the concentric groove 36c is formed by forming a relatively deeper than the central portion (C) and the middle portion (M).

When the relationship between the concentric grooves 36a, 36b, and 36c for each site is summarized above, the distance between the neighboring concentric grooves 36a, 36b and 36c is equal to the center portion (C) ≤ the edge portion (E). <Middle portion (M) relationship, and the depth for each position of these concentric grooves (M) is formed in the middle portion (M) <center portion (C) ≤ edge portion (E) relationship.

On the other hand, the polishing pad 30c shown in Fig. 6 and the grooves 32, 34, 36a, 36b, 36c shown in Figs. 4 and 5 are combined and formed, and these grooves 32, 34, 36a, 36b, and 36c perform the same function as described above.

Each of these embodiments is not limited to performing the wafer W at one side from the rotation center of the polishing pad 10 as in the CMP facility shown in FIG. It can be applied more effectively in response to a facility for eluting upward from the surface plate 12 or a sheet type CMP facility having a diameter of about 0.5 to 30 mm larger than the wafer W, as shown in FIG. 7. .

According to the present invention, by reducing the elongation of the groove at the edge of the polishing pad to reduce the detachment of the slurry, which in turn reduces the waste of the slurry, the differentiation of the spacing and depth between the concentric grooves of the wafer (W) It has the effect of implementing the uniform planarization of the to-be-polished surface as a whole.

Although the present invention has been described in detail only with respect to specific embodiments, it is obvious to those skilled in the art that the present invention can be modified or changed within the scope of the technical idea of the present invention, such modifications or changes are the utility model of the present invention It belongs to the scope of registration claims.

Claims (9)

A plurality of first grooves having a predetermined depth with respect to the polishing surface and forming a shape crossing each other in the X-axis and Y-axis directions; Polishing for CMP having a plurality of second grooves parallel to a depth different from the first groove on the polishing surface, wherein each end portion in the X-axis and Y-axis directions reaches a predetermined interval in the inward direction from the polishing surface edge. pad. The method of claim 1, And the first grooves and the second grooves are arranged at equal intervals. The method of claim 1, The polishing pad for CMP, characterized in that the interval range formed by each end of the second groove with respect to the edge of the polishing surface is 0.5 to 15mm. The method of claim 1, The spacing between the first grooves are formed at intervals of the second grooves or more, and the second grooves are formed in at least two arrangements between the first grooves. The polishing surface on which a plurality of grooves are formed is divided into a center portion, a middle portion around the center portion, and an edge portion around the middle portion, Each forming density of the grooves for the respective portions is formed more densely in the order of the intermediate portion, the edge portion and the center portion. The polishing surface on which a plurality of grooves are formed is divided into a center portion, a middle portion around the center portion, and an edge portion around the middle portion, The grooves are formed in at least two or more of each portion, The interval between the grooves in each of the areas, the smallest on the central portion, the edge portion is made of more than the interval on the center portion, characterized in that the intermediate portion is formed larger than the interval on the edge portion Polishing pad for CMP. The method of claim 6, And said grooves are concentric grooves centered on a rotational center of said polishing surface. The polishing surface on which a plurality of grooves are formed is divided into a center portion, a middle portion around the center portion, and an edge portion around the middle portion, The grooves for the respective portions, the depth of the CMP polishing pad, characterized in that the depth is formed in the order of the middle portion, the center portion and the edge portion more than the depth. The method according to any one of claims 1 to 8, And the polishing surface has at least one through hole so that the slurry is eluted from the bottom.