CN111347345B

CN111347345B - Retaining ring and carrier head for chemical mechanical polishing

Info

Publication number: CN111347345B
Application number: CN202010302238.5A
Authority: CN
Inventors: 孟松林; 赵德文; 王宇
Original assignee: Huahaiqingke Co Ltd
Current assignee: Huahaiqingke Co Ltd
Priority date: 2020-04-16
Filing date: 2020-04-16
Publication date: 2020-10-16
Anticipated expiration: 2040-04-16
Also published as: CN111347345A

Abstract

The invention discloses a retaining ring and a bearing head for chemical mechanical polishing, wherein the retaining ring is composed of an annular part, the annular part is composed of a metal part and a non-metal part, and the non-metal part is molded and formed on the outer peripheral side of the metal part; the annular part comprises a top surface, a bottom surface, an outer side surface and an inner side surface, the top surface is fixedly connected with the bearing head, the bottom surface is abutted against the polishing surface, the outer side surface is arranged on the outer side of the annular part and is connected with the top surface and the bottom surface, the inner side surface is arranged on the inner side of the annular part and is connected with the top surface and the bottom surface, and the bottom surface is provided with a liquid supply groove communicated with the inner side surface and; the top surface is provided with a threaded hole, and the threaded hole is located vertically above the liquid supply tank.

Description

Retaining ring and carrier head for chemical mechanical polishing

Technical Field

The invention belongs to the technical field of chemical mechanical polishing, and particularly relates to a retaining ring and a bearing head for chemical mechanical polishing.

Background

Chemical Mechanical Polishing (CMP) is an ultra-precise surface processing technique for global Planarization. The polishing method generally attracts a substrate to a lower portion of a carrier head, the bottom surface of the substrate having a deposition layer abuts against a rotating polishing pad, and the carrier head is driven by a driving part to rotate in the same direction as the polishing pad and to apply a downward load to the substrate; meanwhile, the polishing solution is supplied between the polishing pad and the substrate, and the material removal of the substrate is realized under the combined action of chemistry and machinery.

The lower portion of the carrier head is provided with a retaining ring, which functions in substrate polishing as follows: on one hand, the retaining ring can prevent the substrate in the polishing process from flying out of the bottom of the bearing head; on the other hand, the bottom of the retaining ring is provided with a groove which can renew the polishing liquid between the substrate and the polishing pad; moreover, the retaining ring is pressed against the polishing pad to participate in the adjustment of the edge pressure of the substrate, which is beneficial to realizing the global planarization of the substrate. In general, in order to pursue the flatness of the bottom surface of the retaining ring, it is necessary to perform break-in (break in) to make the flatness of the bottom surface of the new retaining ring meet a preset requirement when the new retaining ring is used, and in order to shorten the break-in time, a technology such as CN1910012B sets the bottom surface of the retaining ring to be a regular concave-convex structure, but a complicated tool combination such as that disclosed in CN105563306B is generally required to generate such a micro concave-convex structure.

Disclosure of Invention

The present invention aims to solve at least to some extent one of the technical problems existing in the prior art. To this end, a first aspect of the present invention provides a retainer ring for chemical mechanical polishing, the retainer ring being constituted by an annular portion composed of a metal portion and a non-metal portion, the non-metal portion being molded on an outer peripheral side of the metal portion; the annular part comprises a top surface, a bottom surface, an outer side surface and an inner side surface, the top surface is fixedly connected with the bearing head, the bottom surface is abutted against the polishing surface, the outer side surface is arranged on the outer side of the annular part and connected with the top surface and the bottom surface, the inner side surface is arranged on the inner side of the annular part and connected with the top surface and the bottom surface, and the bottom surface is provided with a liquid supply groove communicated with the inner side surface and the outer side surface; the top surface is provided with screw holes with different apertures, and the screw holes are positioned vertically above the liquid supply tank, so that the bottom surface of the retaining ring fixed on the bearing head forms a rugged wave microstructure along the circumferential length direction.

As a preferred embodiment, the threaded holes pass through 1/4-2/3 of the metal part, and the screw hole depths of adjacent threaded holes are not equal.

As a preferred embodiment, the threaded holes are symmetrically distributed with respect to the center of the annular portion, and the distances from the adjacent threaded holes to the center of the annular portion are unequal.

As a preferred embodiment, the apertures of adjacent threaded holes are not equal.

As a preferred embodiment, the distance between the threaded holes on the inner side of the annular part and the outer side surface is 1/2-2/3 of the width of the annular part.

As a preferred embodiment, the distance between the threaded holes on the outer side of the annular part and the outer side surface is 1/4-1/2 of the width of the annular part.

As a preferred embodiment, the flatness of the bottom surface of the retaining ring is between 5 μm and 10 μm.

As a preferred embodiment, a thread sleeve is arranged in the threaded hole, the thread sleeve is a steel wire thread sleeve, and the surface of the steel wire thread sleeve is coated with a protective coating.

As a preferred embodiment, the protective coating is polyethylene terephthalate.

In a second aspect, the invention provides a carrier head for chemical mechanical polishing comprising a retaining ring as described above.

The invention discloses a retaining ring and a bearing head for chemical mechanical polishing, wherein threaded holes with different positions and sizes are arranged on the top surface of the retaining ring to generate rugged wavy microstructures, so that the running-in time of the retaining ring is shortened, and the cost of the chemical mechanical polishing is controlled.

Drawings

The advantages of the invention will become clearer and more readily appreciated from the detailed description given with reference to the following drawings, which are given by way of illustration only, and which do not limit the scope of protection of the invention, wherein:

FIG. 1 is a schematic view of a retainer ring for chemical mechanical polishing according to the present invention;

FIG. 2 is a cross-sectional view of a retaining ring for chemical mechanical polishing according to the present invention;

FIG. 3 is a schematic view of a first embodiment of a retaining ring for chemical mechanical polishing according to the present invention;

FIG. 4 is a top view of the corresponding retaining ring of FIG. 1;

FIG. 5 is a schematic view of a second embodiment of a retaining ring for chemical mechanical polishing according to the present invention;

FIG. 6 is a schematic view of a third embodiment of a retaining ring for chemical mechanical polishing according to the present invention;

FIG. 7 is a schematic structural view of a fourth embodiment of the retaining ring of the present invention;

FIG. 8 is a schematic view of a carrier head according to the present invention;

FIG. 9 is a schematic view of the difference in height of the bottom surface of the retaining ring of the present invention.

Detailed Description

The technical solution of the present invention will be described in detail with reference to the following embodiments and accompanying drawings. The embodiments described herein are specific embodiments of the present invention for the purpose of illustrating the concepts of the invention; the description is intended to be illustrative and exemplary and should not be taken to limit the scope of the invention. In addition to the embodiments described herein, those skilled in the art will be able to employ other technical solutions which are obvious based on the disclosure of the claims and the specification thereof, and these technical solutions include technical solutions which make any obvious replacement or modification of the embodiments described herein.

The drawings in the present specification are schematic views to assist in explaining the concept of the present invention, and schematically show the shapes of respective portions and their mutual relationships. It should be understood that the drawings are not necessarily to scale, the same reference numerals being used to identify the same elements in the drawings in order to clearly show the structure of the elements of the embodiments of the invention.

In the present invention, "Chemical Mechanical Polishing" is also referred to as "Chemical Mechanical Planarization (CMP)" and "substrate" is also referred to as "wafer", and the meaning and the actual function are equivalent.

Fig. 1 is a schematic structural view of a retainer ring 1 for chemical mechanical polishing according to the present invention and fig. 2. The retainer ring 1 is constituted by an annular portion 10, the annular portion 10 being constituted by a metal portion 11 and a non-metal portion 12, the non-metal portion 12 being molded on an outer peripheral side of the metal portion 11. The annular portion 10 includes a top surface 10c, a bottom surface 10d, an outer side surface 10b, and an inner side surface 10 a. The top surface 10c is fixedly attached to the carrier head, and in particular, is disposed at the lower portion of the base of the carrier head such that the lower portion of the base and the inner side of the ring portion 10 form a space in which a substrate to be polished is disposed. The bottom surface 10d abuts against the polishing surface, specifically, the bottom surface 10d of the ring portion abuts against the upper surface of the polishing pad. The outer side surface 10b is disposed outside the annular portion 10 and connected between the top surface 10c and the bottom surface 10d, and the inner side surface 10a is disposed inside the annular portion 10 and connected between the top surface 10c and the bottom surface 10 d. A liquid supply tank 13 is also provided on the bottom surface 10d of the annular portion, and polishing liquid is delivered between the substrate and the polishing pad via the liquid supply tank of the annular portion 10 to participate in polishing of chemical work and mechanical work.

As an embodiment of the invention, the top surface 10c of the ring portion 10 is provided with threaded holes 20, and locking bolts are used to fix the retaining ring 1 to the bottom of the carrier head through the threaded holes 20. Fig. 4 is a top view of the retainer ring 1 for chemical mechanical polishing shown in fig. 1. The top surface 10c is provided with threaded holes 20 with different apertures, and the threaded holes 20 are positioned vertically above the liquid supply tank 13, so that the bottom surface 10d of the retaining ring 1 fixed on the carrier head forms a rugged wave microstructure.

In the present invention, after the retaining ring 1 is fixed to the lower part of the carrier head, a certain height difference is generated after the bottom surface of the annular part 10 of the retaining ring 1 is unfolded to be a plane. Fig. 9 shows that after the bottom surface of the retaining ring 1 is unfolded, peaks and valleys are generated to move along the circumferential direction of the retaining ring, i.e. a certain height difference occurs. The height difference of the bottom surface of the retaining ring is beneficial to shortening the running-in time of the retaining ring and controlling the cost of chemical mechanical polishing. In some embodiments, the flatness of the bottom surface of the retaining ring 1 secured to the carrier head is between 0.1 μm and 20 μm to reduce the break-in time of the retaining ring and to control the cost of chemical mechanical polishing.

For convenience of description, it is now specified that the threaded holes adjacent the inner side surface of the ring portion are inner threaded holes 20a, and correspondingly, the threaded holes adjacent the outer side surface of the ring portion are outer threaded holes 20 b. In the embodiment shown in fig. 3, the inner threaded hole 20a and the outer threaded hole 20b provided in the top surface 10c of the ring portion 10 are not equidistant from the center of the ring portion 10. The threaded holes 20 are arranged in the radial direction of the ring portion 10, which facilitates the creation of a height difference in the radial direction of the retainer ring, so as to shorten the break-in time of the retainer ring.

The distance between the internal threaded bore 20a and the outside of the ring 10 is 1/2-2/3 of the ring width, preferably the distance between the internal threaded bore 20a and the outside of the ring 10 is 7/12 of the ring width. The distance between the outside threaded hole 20b and the outside surface of the ring portion 10 is 1/4-1/2 of the ring portion width, and preferably the distance between the outside threaded hole 20b and the outside surface of the ring portion 10 is 3/8 of the ring portion width. In the embodiment shown in fig. 3, the distance between the inner threaded hole 20a and the outer side surface of the annular part 10 is L1, wherein L1 has a value ranging from 5mm to 20 mm; the distance between the outer threaded hole 20b and the outer side surface of the annular part 10 is L2, wherein the value range of L2 is 2mm-10 mm.

As an embodiment of the present invention, the screw hole diameters of the inner threaded hole 20a and the outer threaded hole 20b may be the same, as shown in fig. 4. The depth of the screw hole of the inner threaded hole 20a is greater than that of the screw hole of the outer threaded hole 20b to equalize the upward pulling force of the locking bolt connected to the retainer ring on the ring portion, and to control the flatness of the bottom surface 10d of the ring portion 10. Specifically, the screw hole depth of the inner threaded hole 20a is 110% to 160% of the screw hole depth of the outer threaded hole 20b, and preferably, the screw hole depth of the inner threaded hole 20a is 130% of the screw hole depth of the outer threaded hole 20 b.

As an embodiment of the present invention, the screw holes 20 are formed through 1/4-2/3 of the metal part 11, and in some embodiments, the screw hole depth of the inner screw hole 20a is 8mm, so that it is coupled with a locking bolt to adjust the flatness of the bottom surface of the ring part 10.

As another embodiment of the present invention, the screw hole diameters of the inner threaded hole 20a and the outer threaded hole 20b may be different, as shown in fig. 3. In this embodiment, the bore diameter of the outside threaded bore 20b is slightly larger than the bore diameter of the inside threaded bore 20 a. In some embodiments, the bore diameter of the outside threaded bore 20b is 110% -140% of the bore diameter of the inside threaded bore 20 a. In the embodiment shown in fig. 2, the inner threaded bore 20a has a major diameter of 13.157mm, a middle diameter of 12.301mm, and a minor diameter of 11.445 mm.

As an embodiment of the present invention, the top surface 10c of the ring portion 10 may be provided with one outer threaded hole 20b adjacent to 2-4 inner threaded holes 20a to equalize the upward pulling force of the locking bolt coupled to the retaining ring on the ring portion and control the flatness of the bottom surface 10d of the ring portion 10. Preferably, the top surface 10c of the ring portion 10 may be provided with one outer threaded hole 20b adjacent to 3 inner threaded holes 20 a.

As another embodiment of the present invention, the upward pulling force of the locking bolt of the retaining ring on the ring part is realized by adjusting the arrangement position of the threaded hole 20 of the top surface 10c of the ring part 10, the diameter of the threaded hole and the depth of the threaded hole, so as to control the flatness of the bottom surface of the retaining ring. Preferably, the flatness of the bottom surface of the retaining ring is between 5 μm and 10 μm.

In the present invention, the distance between the threaded hole 20 in the top surface of the ring portion 10 of the retainer ring 1 and the center position of the ring portion 10 may be equal. The screw hole diameters of the screw holes 20 are the same and the screw hole depths of the adjacent screw holes 20 are different, as shown in fig. 5. The screw hole depth of the threaded hole 20 is different from the screw hole depth of the adjacent threaded hole 20 by 20-50%. Preferably, the screw hole depths of adjacent screw holes 20 differ by 30%. As a variation of the present embodiment, as shown in fig. 6, the distance between the screw hole 20 on the top surface of the ring portion 10 and the center position of the ring portion 10 is equal, and the screw hole diameters of the adjacent screw holes 20 are different. In some embodiments, the screw hole diameters of adjacent threaded holes 20 differ by 10% -80%, preferably, the screw hole diameters of adjacent threaded holes 20 differ by 20% -40%.

The threaded holes are formed in the annular portion 10, and the reliability of the fixing of the retainer ring is affected by repeated mounting and dismounting of the lock bolt. Thus, the threaded sleeve 14 is provided on the top surface of the annular portion of the retaining ring, i.e. the threaded bore 20 of the annular portion 10, as shown in fig. 7. As an embodiment of the present invention, the thread bushing 14 is a steel wire thread bushing, and the surface of the steel wire thread bushing is coated with a protective coating. The protective coating can increase the lifting force of the locking bolt on the retaining ring, and enhance the control of the flatness of the bottom surface of the retaining ring. As one aspect of this embodiment, the protective coating is polyethylene terephthalate (PET). The protective coating is ultra-fine polyethylene terephthalate powder that is sprayed on the inside of the threaded sleeve 14. It is understood that the protective coating may also be Polyethylene (PE), Polymethylmethacrylate (PMMA), Polycarbonate (PC), Polyurethane (PU), polypropylene (PP), Polystyrene (PS), Polyvinylchloride (PVC), Nylon (Nylon), Polytetrafluoroethylene (PTFE), and/or Polyoxymethylene (POM).

As a variation of this embodiment, a threaded sleeve 14 with a protective coating may be spaced from the threaded bore 20 in the top surface 10c of the ring portion 10 to control the flatness of the bottom surface of the retaining ring. In some embodiments, the protective coated threaded sleeve 14 may be spaced 2-4 threaded holes 20 apart, and preferably, the protective coated threaded sleeve 14 may be spaced 2 threaded holes 20 apart to control the flatness of the bottom surface of the retaining ring.

For ease of design and machining, the threaded hole 20 is generally provided directly above the side wall of the feed tank 13 or in the center of the upper surface of the feed tank, in order to reduce machining costs. Further, in order to more efficiently generate the wave microstructure, the outer diameter of the screw hole 20 should be 1.5 to 3 times the width of the liquid supply tank 13.

In a second aspect, the present invention provides a carrier head 2 for CMP, which is schematically configured, as shown in fig. 8, and comprises the retaining ring 1 as described above, wherein the retaining ring is pulled upward by the locking bolts of the retaining ring by adjusting the position of the threaded holes 20 on the top surface 10c of the annular portion 10c of the retaining ring, the diameter of the threaded holes, and the depth of the threaded holes, so as to control the flatness of the bottom surface of the retaining ring. The flatness of the bottom surface of the retainer ring is controlled to be about 7 μm to shorten the break-in time of the retainer ring and to control the cost of chemical mechanical polishing.

In the description herein, references to the description of the term "one embodiment," "some embodiments," "an illustrative embodiment," "an example," "a specific example," or "some examples" or the like mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

While embodiments of the invention have been shown and described, it will be understood by those of ordinary skill in the art that: various changes, modifications, substitutions and alterations can be made to the embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.

Claims

1. A retainer ring for chemical mechanical polishing, characterized in that the retainer ring is constituted by an annular portion composed of a metal portion and a non-metal portion, the non-metal portion being molded on an outer peripheral side of the metal portion; the annular part comprises a top surface, a bottom surface, an outer side surface and an inner side surface, the top surface is fixedly connected with the bearing head, the bottom surface is abutted against the polishing surface, the outer side surface is arranged on the outer side of the annular part and connected with the top surface and the bottom surface, the inner side surface is arranged on the inner side of the annular part and connected with the top surface and the bottom surface, and the bottom surface is provided with a liquid supply groove communicated with the inner side surface and the outer side surface; the top surface is provided with threaded holes with different apertures, the threaded holes are positioned vertically above the liquid supply tank, so that the bottom surface of the retaining ring fixed on the bearing head forms a rugged wave microstructure along the circumferential length direction, the threaded holes penetrate through 1/4-2/3 of the metal part, and the screw hole depths of adjacent threaded holes are unequal.

2. The retaining ring of claim 1, wherein the threaded holes are symmetrically distributed about a center of the ring portion, and adjacent threaded holes are at unequal distances from the center of the ring portion.

3. The retaining ring of claim 1, wherein the bore diameters of the threaded bores of adjacent threaded bores are not equal.

4. The retaining ring of claim 2, wherein the threaded holes on the inside of the ring portion are spaced from the outside by a distance of 1/2-2/3 of the width of the ring portion.

5. The retaining ring of claim 2, wherein the threaded bore outside the ring portion is spaced from the outer side surface by a distance of 1/4-1/2 of the width of the ring portion.

6. The retaining ring of claim 1, wherein the bottom surface of the retaining ring has a flatness of between 5 μ ι η and 10 μ ι η.

7. The retaining ring of claim 1, wherein a threaded sleeve is disposed within the threaded bore, the threaded sleeve being a wire threaded sleeve, a surface of the wire threaded sleeve being coated with a protective coating.

8. The retaining ring of claim 7, wherein the protective coating is polyethylene terephthalate.

9. A carrier head for chemical mechanical polishing, comprising: comprising a retaining ring according to any of claims 1 to 8.