JP2014179660A - Abrasive pad for eddy current endpoint detection - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an abrasive pad for eddy current endpoint detection.SOLUTION: An abrasive pad for polishing a semiconductor substrate by using eddy current endpoint detection is provided. A method of manufacturing an abrasive pad for polishing a semiconductor substrate by using eddy current endpoint detection is also provided. The abrasive pad for polishing a semiconductor substrate includes a cast homogeneous polishing body having a polishing front surface and a back surface, and an endpoint detection region arranged in the cast homogeneous polishing body and covalently bonded to the cast homogeneous polishing body. The endpoint detection region includes a material different from the cast homogeneous polishing body, and at least a part of the endpoint detection region is set back from the back surface of the cast homogeneous polishing body.

Description

  Embodiments of the present invention relate to the field of chemical mechanical polishing (CMP), and more specifically to a polishing pad for eddy current endpoint detection.

  Chemical mechanical planarization or chemical mechanical polishing, commonly abbreviated as CMP, is a technique used in semiconductor manufacturing to planarize a semiconductor wafer or other substrate.

  The process typically uses an abrasive and a corrosive chemical slurry (generally a colloid) in conjunction with a larger diameter polishing pad and retaining ring than the wafer. The polishing pad and wafer are pressed together by a dynamic polishing head and held in place by a plastic retaining ring. The dynamic polishing head is rotated during polishing. This approach aids in material removal and tends to flatten any irregular topography, making the wafer flat or planar. This may be necessary to set up the wafer for the formation of additional circuit elements. For example, this may be necessary to bring the entire surface within the depth of field of the photolithography system or to selectively remove material based on its location. Typical depth-of-field requirements are at the angstrom level for the latest 50 nanometer or smaller technology nodes.

  The material removal process is not as simple as abrasive grinding like abrasive paper on wood. The chemicals in the slurry also react with and / or weaken the material being removed. The abrasive accelerates this weakening process, and the polishing pad helps wipe off the reacted material from the surface.

  One problem in CMP is determining whether the polishing process is complete, for example, whether the substrate layer has been planarized to the desired flatness or thickness, or when the desired amount of material has been removed. It is to be. Overpolishing of the conductive layer or film leads to increased circuit resistance. On the other hand, insufficient polishing of the conductive layer can lead to electrical shorts. Variations in the initial thickness of the substrate layer, the slurry composition, polishing pad conditions, the relative speed between the polishing pad and the substrate, and the load on the substrate can cause variations in the material removal rate. These variations cause variations in the time required to reach the polishing endpoint. Thus, the polishing endpoint cannot often be determined simply as a function of polishing time.

  One way to determine the polishing endpoint is to monitor the polishing of the metal layer on the substrate in situ, for example, by optical or electrical sensors. One monitoring technique is to induce eddy currents in the metal layer by the magnetic field and detect changes in magnetic flux as the metal layer is removed. The magnetic flux generated by the eddy current is in the opposite direction to the excitation flux. This magnetic flux is proportional to the layer thickness, proportional to the resistance of the metal layer, and proportional to the eddy current. Thus, a change in the metal layer thickness causes a change in the bundle generated by the eddy current. This bundle change induces a current change in the primary coil and can be measured as a change in impedance. As a result, the change in coil impedance reflects the change in metal layer thickness. However, the polishing pad may need to be modified to accommodate eddy current measurements during real-time polishing of the metal layer on the substrate.

  Thus, in addition to advances in slurry technology, polishing pads play an important role in the increasingly complex CMP operations. However, further improvements are needed in the evolution of CMP pad technology.

  Embodiments of the present invention include a polishing pad for eddy current endpoint detection.

  In some embodiments, a polishing pad for polishing a semiconductor substrate includes a cast homogeneous polishing body. The cast homogeneous abrasive body has a polishing surface and a back surface. The polishing pad also includes an endpoint detection region disposed within the cast homogeneous abrasive body and covalently coupled to the cast homogeneous abrasive body. The end point detection region is made of a material different from that of the cast homogeneous abrasive body, and at least a part of the end point detection region is set back with respect to the back surface of the cast homogeneous abrasive body.

  In another embodiment, a method of manufacturing a polishing pad for polishing a semiconductor substrate includes forming a cast homogeneous polishing body. The cast homogeneous abrasive body has a polishing surface and a back surface. The method also includes forming an endpoint detection region disposed within the cast homogeneous abrasive body and covalently coupled to the cast homogeneous abrasive body. The end point detection region is made of a material different from that of the cast homogeneous abrasive body, and at least a part of the end point detection region is set back with respect to the back surface of the cast homogeneous abrasive body.

  In certain embodiments, a polishing pad for polishing a semiconductor substrate includes a cast homogeneous abrasive body having a polishing surface and a back surface. A groove pattern is disposed in the polishing surface, and the groove pattern has a bottom depth. The polishing pad also includes an endpoint detection region formed within the cast homogeneous polishing body. The end point detection region has a first surface oriented with respect to the polishing surface and a second surface oriented with respect to the back surface. At least a portion of the first surface is flush with the bottom depth of the groove pattern and interrupts the groove pattern. The second surface is retracted into the cast homogeneous abrasive body relative to the back surface.

  In another embodiment, a method of manufacturing a polishing pad includes forming a polishing pad precursor mixture in a forming mold. The forming mold lid is positioned in the polishing pad precursor mixture. The lid has a groove pattern disposed thereon, and the groove pattern has a break area. The polishing pad precursor mixture is cured to provide a cast homogeneous abrasive body having a polishing surface and a back surface. A pattern of grooves from the lid is disposed within the polishing surface, and the pattern of grooves has a bottom depth. An end point detection region is provided within the cast homogeneous abrasive body, and the end point detection region has a first surface oriented with respect to the polishing surface and a second surface oriented with respect to the back surface. At least a portion of the first surface is flush with the bottom depth of the groove pattern and includes an interrupted region of the groove pattern. On the other hand, the second surface is retracted into the cast homogeneous abrasive relative to the back surface.

  In one embodiment, a method of manufacturing a polishing pad for polishing a semiconductor substrate includes forming a polishing pad in a casting process that includes a cast homogeneous abrasive body having a polishing surface and a back surface. Including. The groove pattern is disposed within the polishing surface, and the groove pattern has a bottom depth. The polishing pad also includes an endpoint detection region formed within the cast homogeneous polishing body. The end point detection region has a first surface oriented with respect to the polishing surface and a second surface oriented with respect to the back surface. At least a portion of the first surface is flush with the bottom depth of the groove pattern and interrupts the groove pattern. The second surface is retracted into the cast homogeneous abrasive body relative to the back surface.

  In certain embodiments, a method of manufacturing a polishing pad includes forming a partially cured endpoint detection region precursor in a first forming mold. The partially cured endpoint detection area precursor is positioned on the receiving area of the lid of the second forming mold. A polishing pad precursor mixture is provided in the second forming mold. By aligning the lid and base of the second forming mold, the partially cured endpoint detection region precursor is transferred into the polishing pad precursor mixture. The polishing pad precursor mixture and the partially cured endpoint detection region precursor are then heated to provide a cast homogeneous abrasive body that is covalently bonded to the cured endpoint detection region precursor and is cast. The homogeneous polishing body has a polishing surface and a back surface. The cured endpoint detection area precursor is then retracted against the back surface of the cast homogeneous abrasive body, placed in the cast homogeneous abrasive body, and covalently bonded to the cast homogeneous abrasive body. Provide an end point detection area.

In another embodiment, a method of manufacturing a polishing pad includes placing a support structure in a first forming mold. The detection region precursor mixture is provided in the first forming template above the support structure. The partially cured endpoint detection region precursor is formed by heating the detection region precursor mixture in the first forming template, and the partially cured endpoint detection region precursor is coupled to the support structure. Is done. The support structure and the partially cured endpoint detection area precursor are positioned on the retracted receiving area of the lid of the second forming mold by connecting the support structure to the retracted receiving area of the lid. It is done. A polishing pad precursor mixture is provided in the second forming mold. By aligning the lid and base of the second forming mold, the partially cured endpoint detection region precursor is transferred into the polishing pad precursor mixture. The polishing pad precursor mixture and the partially cured end point detection region precursor are heated to provide a cast homogeneous abrasive body that is covalently bonded to the cured end point detection region precursor. The polishing body has a polishing surface and a back surface, and the end point detection region is connected to the support structure. The support structure is removed from the end point detection area.
For example, the present invention provides the following items.
(Item 1)
A polishing pad for polishing a semiconductor substrate,
A cast homogeneous abrasive body having an abrasive surface and a back surface;
An end point detection region disposed within the cast homogeneous abrasive body and covalently coupled to the cast homogeneous abrasive body;
With
The end point detection region comprises a material different from that of the cast homogeneous polishing body, and at least a part of the end point detection region is set back with respect to the back surface of the cast homogeneous polishing body. pad.
(Item 2)
The polishing pad according to item 1, wherein at least a part of the end point detection region is set back with respect to the polishing surface of the cast homogeneous polishing body.
(Item 3)
Item 2. The soft polishing pad according to Item 1, wherein the end point detection region is a locally transparent (LAT) region.
(Item 4)
Item 4. The polishing pad according to Item 3, wherein the hardness of the end point detection region is higher than the hardness of the cast homogeneous polishing body.
(Item 5)
The polishing pad according to item 1, wherein the end point detection region is an opaque region having a hardness different from the hardness of the cast homogeneous polishing body.
(Item 6)
Item 6. The polishing pad according to Item 5, wherein the hardness of the end point detection region is higher than the hardness of the cast homogeneous polishing body.
(Item 7)
Item 6. The polishing pad according to Item 5, wherein the hardness of the end point detection region is lower than the hardness of the cast homogeneous polishing body.
(Item 8)
The polishing pad according to item 1, wherein the entire end point detection region is retracted with respect to the back surface of the cast homogeneous polishing body.
(Item 9)
The polishing pad according to item 1, wherein only the inner part of the end point detection region is retracted with respect to the back surface of the cast homogeneous polishing body.
(Item 10)
Item 2. The polishing pad of item 1, wherein the cast homogeneous abrasive body comprises a thermosetting closed cell polyurethane material.
(Item 11)
Item 2. The polishing pad of item 1, wherein the polishing surface comprises a pattern of grooves disposed within the polishing surface.
(Item 12)
A method of manufacturing a polishing pad for polishing a semiconductor substrate, comprising:
Forming a cast homogeneous abrasive body having an abrasive surface and a back surface;
Forming an endpoint detection region disposed within the cast homogenous abrasive body and covalently coupled to the cast homogenous abrasive body;
Including
The end point detection region comprises a material different from the cast homogeneous abrasive body, and at least a portion of the end point detection region is retracted relative to the back surface of the cast homogeneous abrasive body. .
(Item 13)
13. The method of item 12, wherein the end point detection area is a local transparency (LAT) area.
(Item 14)
Item 14. The method according to Item 13, wherein the hardness of the end point detection region is higher than the hardness of the cast homogeneous abrasive.
(Item 15)
13. The method according to item 12, wherein the end point detection area is an opaque area having a hardness different from that of the cast homogeneous abrasive.
(Item 16)
Item 16. The method according to Item 15, wherein the hardness of the end point detection region is higher than the hardness of the cast homogeneous abrasive.
(Item 17)
Item 16. The method according to Item 15, wherein the hardness of the end point detection region is lower than the hardness of the cast homogeneous abrasive.
(Item 18)
13. The method according to item 12, wherein the entire end point detection region is retracted with respect to the back surface of the cast homogeneous abrasive.
(Item 19)
13. The method according to item 12, wherein only an inner part of the end point detection region is retracted with respect to the back surface of the cast homogeneous abrasive.
(Item 20)
13. A method according to item 12, wherein the cast homogeneous abrasive body comprises a thermosetting closed cell polyurethane material.
(Item 21)
13. The method of item 12, wherein the polishing surface comprises a pattern of grooves disposed within the polishing surface.
(Item 22)
A polishing pad for polishing a semiconductor substrate,
A cast homogeneous abrasive body having an abrasive surface and a back surface;
A groove pattern disposed in the polishing surface, the groove pattern having a bottom depth; and
An end point detection region formed in the cast homogeneous polishing body;
With
The end point detection region has a first surface oriented with respect to the polishing surface and a second surface oriented with respect to the back surface, and at least a part of the first surface is Is flush with the depth of the bottom of the groove pattern, interrupts the groove pattern, and the second surface is retracted into the cast homogenous abrasive against the back surface; Polishing pad.
(Item 23)
Item 23. The polishing pad of item 22, wherein the entire first surface of the end point detection region is essentially flush with the bottom depth of the groove pattern.
(Item 24)
The first surface of the endpoint detection region comprises a second groove pattern having a depth essentially coplanar with the bottom depth of the groove pattern disposed within the polishing surface. 22. The polishing pad according to 22.
(Item 25)
The individual grooves of both the groove pattern and the second groove pattern are spaced apart by a width, and the second groove pattern is offset from the groove pattern by a distance greater than the width. Item 25. The polishing pad according to Item 24.
(Item 26)
Item 23. The polishing pad of item 22, wherein the cast homogeneous abrasive body comprises a thermosetting closed cell polyurethane material.
(Item 27)
23. A polishing pad according to item 22, wherein the cast homogeneous polishing body including the end point detection region is opaque.
(Item 28)
A method of manufacturing a polishing pad for polishing a semiconductor substrate, comprising:
Forming a polishing pad precursor mixture in a forming mold;
Locating a lid of the forming mold in the polishing pad precursor mixture, the lid having a groove pattern disposed on the lid, the groove pattern having a break region; And
Curing the polishing pad precursor mixture to provide a cast homogeneous abrasive body having a polishing surface and a back surface, wherein the pattern of grooves from the lid is within the polishing surface Arranged, wherein the groove pattern has a bottom depth;
Providing an endpoint detection area within the cast homogeneous abrasive body;
Including
The end point detection region has a first surface oriented with respect to the polishing surface and a second surface oriented with respect to the back surface, and at least a part of the first surface has the groove The second surface is retracted into the cast homogenous abrasive body relative to the back surface, the second surface being flush with the bottom depth of the pattern Method.
(Item 29)
29. A method according to item 28, wherein providing the end point detection area is performed by digging out a part of the cast homogeneous abrasive body.
(Item 30)
29. The method of item 28, wherein providing the end point detection region is performed by removing a sacrificial layer embedded in the cast homogeneous abrasive.
(Item 31)
29. A method according to item 28, wherein the entire first surface of the end point detection region is essentially flush with the bottom depth of the groove pattern.
(Item 32)
The first surface of the end point detection region has a depth that is essentially flush with the bottom depth of the groove pattern disposed within the polishing surface of the cast homogeneous abrasive body. 29. A method according to item 28, comprising a groove pattern.
(Item 33)
Individual grooves of both the groove pattern and the second groove pattern are spaced apart by a width, and the second groove pattern is separated from the first groove pattern by a distance greater than the width. The method of item 32, wherein the method is offset.
(Item 34)
33. A method according to item 32, wherein the cast homogeneous abrasive body comprises a thermosetting closed cell polyurethane material.
(Item 35)
29. A method according to item 28, wherein the cast homogeneous abrasive body including the end point detection region is opaque.
(Item 36)
A method of manufacturing a polishing pad for polishing a semiconductor substrate, comprising:
The method includes forming a polishing pad by a casting process;
The polishing pad is
A homogeneous abrasive having a polishing surface and a back surface;
A groove pattern disposed in the polishing surface, the groove pattern having a bottom depth; and
An end point detection region formed in the cast homogeneous polishing body;
With
The end point detection region has a first surface oriented with respect to the polishing surface and a second surface oriented with respect to the back surface, and at least a part of the first surface is Is flush with the depth of the bottom of the groove pattern, interrupts the groove pattern, and the second surface is retracted into the cast homogenous abrasive against the back surface; Method.
(Item 37)
38. The method of item 36, wherein the entire first surface of the endpoint detection region is essentially flush with the bottom depth of the groove pattern.
(Item 38)
The first surface of the endpoint detection region comprises a second groove pattern having a depth essentially coplanar with the bottom depth of the groove pattern disposed within the polishing surface. 36. The method according to 36.
(Item 39)
The individual grooves of both the groove pattern and the second groove pattern are spaced apart by a width, and the second groove pattern is offset from the groove pattern by a distance greater than the width. 39. The method according to item 38.
(Item 40)
38. A method according to item 36, wherein the cast homogeneous abrasive body comprises a thermosetting closed cell polyurethane material.
(Item 41)
37. A method according to item 36, wherein the cast homogeneous abrasive body including the end point detection region is opaque.
(Item 42)
A method of manufacturing a polishing pad for polishing a semiconductor substrate, comprising:
Forming a partially cured endpoint detection region precursor in a first forming mold;
Positioning the partially cured endpoint detection area precursor on the receiving area of the lid of the second forming mold;
Providing a polishing pad precursor mixture in the second forming mold;
Moving the partially cured endpoint detection region precursor into the polishing pad precursor mixture by combining the lid and base of the second forming mold; and
By heating the polishing pad precursor mixture and the partially cured endpoint detection region precursor to provide a cast homogeneous abrasive body that is covalently bonded to the cured endpoint detection region precursor The cast homogeneous abrasive has an abrasive surface and a back surface;
The cured end point detection region precursor is moved backward with respect to the back surface of the cast homogeneous abrasive body, and is disposed in the cast homogeneous abrasive body and shared with the cast homogeneous abrasive body. Providing a combined endpoint detection area;
Including the method.
(Item 43)
43. The method of item 42, wherein the retracting is performed by digging out a portion of the cured endpoint detection region precursor.
(Item 44)
43. A method according to item 42, wherein the partially cured endpoint detection region precursor includes a sacrificial layer, and the step of retreating is performed by removing the sacrificial layer.
(Item 45)
43. A method according to item 42, wherein the end point detection region comprises a material different from that of the cast homogeneous abrasive.
(Item 46)
46. A method according to item 45, wherein the end point detection region is a locally transparent (LAT) region.
(Item 47)
46. A method according to item 45, wherein the end point detection region is an opaque region having a hardness different from the hardness of the cast homogeneous abrasive.
(Item 48)
43. A method according to item 42, wherein the entire end point detection region is retracted relative to the back surface of the cast homogeneous abrasive.
(Item 49)
43. A method according to item 42, wherein only an inner part of the end point detection region is retracted with respect to the back surface of the cast homogeneous abrasive.
(Item 50)
43. A method according to item 42, wherein the cast homogeneous abrasive body comprises a thermosetting closed cell polyurethane material.
(Item 51)
43. The method of item 42, wherein the polishing surface comprises a pattern of grooves disposed within the polishing surface, wherein the groove pattern is formed from a lid of the second forming mold.
(Item 52)
A method of manufacturing a polishing pad for polishing a semiconductor substrate, comprising:
Installing the support structure in the first forming mold;
Providing a detection region precursor mixture in the first forming template above the support structure;
Heating the detection region precursor mixture in the first forming mold to form a partially cured endpoint detection region precursor, the partially cured endpoint detection region precursor The body is coupled to the support structure;
By connecting the support structure to the retracted receiving area of the lid of the second forming mold, the support structure and the partial on the retracted receiving area of the lid of the second forming mold Locating the cured endpoint detection region precursor to
Providing a polishing pad precursor mixture in the second forming mold;
Moving the partially cured endpoint detection region precursor into the polishing pad precursor mixture by combining the lid and base of the second forming mold; and
By heating the polishing pad precursor mixture and the partially cured endpoint detection region precursor to provide a cast homogeneous abrasive body that is covalently bonded to the cured endpoint detection region precursor. The cast homogenous abrasive body has a polishing surface and a back surface, and the end point detection region is connected to the support structure;
Removing the support structure from the end point detection region;
Including the method.
(Item 53)
Subsequent to the heating, the cured end point detection region precursor is retracted relative to the back surface of the cast homogeneous abrasive body, thereby being disposed within the cast homogeneous abrasive body, and 53. The method of item 52, further comprising providing an endpoint detection region that is covalently coupled to the cast homogeneous abrasive.
(Item 54)
53. The method of item 52, wherein the support structure comprises a hard epoxy board.
(Item 55)
55. The method of item 54, wherein providing the detection region precursor mixture into the first forming template comprises providing the detection region precursor mixture on a polymer film adhered to the support structure. .
(Item 56)
56. The method of item 55, wherein coupling the support structure to the retracted receiving area of the lid comprises adhering the support structure to the retracted receiving area with a piece of double-sided tape. .
(Item 57)
54. The method of item 53, wherein the retreating is performed by digging out a portion of the cured endpoint detection region precursor.
(Item 58)
54. The method of item 53, wherein the partially cured endpoint detection region precursor includes a sacrificial layer, and the retracting is performed by removing the sacrificial layer.
(Item 59)
53. A method according to item 52, wherein the end point detection region comprises a material different from that of the cast homogeneous abrasive.
(Item 60)
60. The method of item 59, wherein the end point detection area is a locally transparent (LAT) area.
(Item 61)
60. The method according to Item 59, wherein the end point detection area is an opaque area having a hardness different from that of the cast homogeneous abrasive.
(Item 62)
54. A method according to item 53, wherein the entire end point detection region is retracted with respect to the back surface of the cast homogeneous abrasive.
(Item 63)
54. A method according to item 53, wherein only an inner part of the end point detection region is retracted with respect to the back surface of the cast homogeneous abrasive.
(Item 64)
53. A method according to item 52, wherein the cast homogeneous abrasive body comprises a thermosetting closed cell polyurethane material.
(Item 65)
53. The method of item 52, wherein the polishing surface comprises a groove pattern disposed within the polishing surface, the groove pattern being formed from a lid of the second forming mold.

FIG. 1A illustrates a cross-sectional view of a polishing pad adapted for eddy current endpoint detection to polish a semiconductor substrate, in accordance with an embodiment of the present invention. FIG. 1B illustrates a top view of the polishing pad of FIG. 1A, according to an embodiment of the invention. FIG. 2A illustrates a cross-sectional view of a polishing pad adapted for eddy current endpoint detection to polish a semiconductor substrate according to an embodiment of the present invention. FIG. 2B illustrates a top view of the polishing pad of FIG. 2A, according to an embodiment of the invention. FIG. 3A illustrates a cross-sectional view of a polishing pad adapted for eddy current endpoint detection to polish a semiconductor substrate, in accordance with an embodiment of the present invention. FIG. 3B illustrates a cross-sectional view of a polishing pad adapted for eddy current endpoint detection to polish a semiconductor substrate, in accordance with an embodiment of the present invention. FIG. 4A illustrates a cross-sectional view of a polishing pad adapted for eddy current endpoint detection to polish a semiconductor substrate, in accordance with an embodiment of the present invention. FIG. 4B illustrates a top view of the polishing pad of FIG. 4A, according to an embodiment of the invention. FIG. 5A illustrates a cross-sectional view of a polishing pad adapted for eddy current endpoint detection to polish a semiconductor substrate, in accordance with an embodiment of the present invention. FIG. 5B illustrates a top view of the polishing pad of FIG. 5A, according to an embodiment of the invention. 6A-6T illustrate cross-sectional views of operations used in manufacturing a polishing pad, according to an embodiment of the present invention. 6A-6T illustrate cross-sectional views of operations used in manufacturing a polishing pad, according to an embodiment of the present invention. 6A-6T illustrate cross-sectional views of operations used in manufacturing a polishing pad, according to an embodiment of the present invention. 6A-6T illustrate cross-sectional views of operations used in manufacturing a polishing pad, according to an embodiment of the present invention. 6A-6T illustrate cross-sectional views of operations used in manufacturing a polishing pad, according to an embodiment of the present invention. 6A-6T illustrate cross-sectional views of operations used in manufacturing a polishing pad, according to an embodiment of the present invention. 7A-7D illustrate cross-sectional views of operations used in manufacturing a polishing pad, according to an embodiment of the present invention. 8A-8F illustrate cross-sectional views of operations used in the manufacture of a polishing pad, according to an embodiment of the present invention. 8A-8F illustrate cross-sectional views of operations used in the manufacture of a polishing pad, according to an embodiment of the present invention. 9A-9F illustrate cross-sectional views of operations used in the manufacture of a polishing pad, according to an embodiment of the invention. 9A-9F illustrate cross-sectional views of operations used in the manufacture of a polishing pad, according to an embodiment of the invention. FIG. 10 illustrates an isometric side view of a polishing apparatus that is compatible with a polishing pad for eddy current endpoint detection, according to an embodiment of the present invention. FIG. 11 illustrates a cross-sectional view of a polishing apparatus with an eddy current endpoint detection system and a polishing pad and compatible with an eddy current endpoint detection system, according to an embodiment of the present invention.

  A polishing pad for polishing a semiconductor substrate using eddy current endpoint detection is described herein. In the following description, numerous specific details are set forth, such as specific polishing pad compositions and designs, in order to provide a thorough understanding of embodiments of the present invention. It will be apparent to those skilled in the art that embodiments of the present invention may be practiced without these specific details. In other instances, well known processing techniques, such as a slurry and polishing pad combination for performing CMP of a semiconductor substrate, have not been described in detail so as not to unnecessarily obscure embodiments of the present invention. Furthermore, it should be understood that the various embodiments shown in the figures are illustrative representations and are not necessarily drawn to scale.

  The polishing pad may be formed to include a region that is designed to accommodate an eddy current detection probe that is incorporated into the mounting plate of the chemical mechanical polishing apparatus. For example, in certain embodiments of the invention, individual material regions are included in the polishing pad during casting of the polishing pad. The individual material regions are shaped and sized to accommodate eddy current probes protruding from the mounting board. Further, the region can be made at least somewhat transparent to assist in aligning the polishing pad on a mounting board containing eddy current probes. In another embodiment of the invention, the polishing pad is generally a cast homogeneous abrasive body with a recess formed in a region on the back side of the abrasive body. The recess may also have a shape and size to accommodate an eddy current probe protruding from the mounting board. In one embodiment, the single recess is sized to accommodate the entire portion of the eddy current detector that protrudes above the mounting board. In addition, if the cast homogeneous abrasive is opaque, a pattern can be formed in the polishing surface of the polishing pad, the pattern showing or entering the location of the recess on the back side of the polishing pad It becomes a clue. A clue may be used to assist in aligning the polishing pad on the mounting board that includes the eddy current probe.

  According to an embodiment of the present invention, a polishing pad for polishing a semiconductor substrate is provided to allow a device such as a sensor to extend above a mounting plate for a CMP tool. For example, in one embodiment, the polishing pad includes design features that facilitate its use on a polishing tool to which an eddy current endpoint detection system is attached and in a CMP process that utilizes eddy current endpoint detection. The polishing pad design feature may generally allow the eddy current sensor of the CMP tool to rise above the plane of the CMP tool mount and extend into the back of the polishing pad as the polishing process is in progress. In certain embodiments, the design feature allows this to occur without affecting the overall polishing performance of the polishing pad. The design feature may also allow the polishing pad to be placed on the mounting plate in a precise orientation such that the eddy current sensor rises above the plane of the mounting plate without interference.

  In certain embodiments, the design features include a recess in the back surface of the polishing pad that has an appropriate size, shape and alignment for alignment with the eddy current sensor. In certain embodiments, another design feature includes means for visually orienting the polishing pad on the mounting plate to align with the location of a sensor, such as an eddy current sensor. In one embodiment, the polishing pad has a transparent portion. In another embodiment, the polishing pad is generally opaque but includes visible signals or cues, such as an interrupt pattern on its polishing surface that indicates the location of the corresponding back recess.

  In one aspect of the invention, a polishing pad for use with eddy current detection includes an endpoint detection region made of a material different from the rest of the polishing pad. For example, FIG. 1A illustrates a cross-sectional view of a polishing pad adapted for eddy current endpoint detection, according to an embodiment of the present invention. FIG. 1B illustrates a top view of the polishing pad of FIG. 1A, according to an embodiment of the invention.

  With reference to FIGS. 1A and 1B, a polishing pad 100 includes a cast homogeneous abrasive body 102. The cast homogeneous abrasive 102 has an abrasive surface 104 and a back surface 106 (note that the back surface 106 is depicted only in FIG. 1A). The polishing surface 104 may include a plurality of grooves 150 as depicted in FIG. The end point detection region 108 is disposed in the cast homogeneous polishing body 102. The end point detection region 108 is made of a material 110 different from the cast homogeneous abrasive 102. The material 110 is covalently bonded 112 with the material of the cast homogeneous abrasive 102.

  In some embodiments, the endpoint detection area 108 is thinner than most of the polishing pad, with or without grooves, as depicted in FIG. 1A. For example, in one embodiment, the thickness (T3) of the material 110 in the endpoint detection region 108 is less than the thickness (T1) of the cast homogeneous abrasive 102. In particular, T3 is thinner than the thickness (T2) of the portion of the cast homogeneous abrasive 102 excluding the grooves 150 on the abrasive surface 104. In a specific embodiment, T 1 is the thinnest portion of polishing pad 100.

  Referring again to FIG. 1A, at least a portion of the material 110 in the endpoint detection region 108 is retracted relative to the back surface 106 of the cast homogeneous abrasive 102. For example, in one embodiment, the material 110 of the endpoint detection area 108 is generally retracted relative to the back surface 106 of the cast homogeneous abrasive body 102. In particular, the material 110 of the endpoint detection region 108 has a first surface 114 and a second surface 116. The second surface 116 is retracted by an amount D relative to the back surface 106. In one embodiment, the second surface 116 is retracted by an amount D sufficient to accommodate an eddy current probe protruding from the mounting plate of the chemical mechanical polishing apparatus. In a specific embodiment, the recession depth D is approximately 70 mils (thousandths of an inch) below the surface 106.

  Referring to FIG. 1B, in one embodiment, the polished surface 104 of the cast homogeneous abrasive body 102 has a pattern of grooves disposed therein, ie, a pattern formed from the grooves 150 shown in FIG. 1A. Have. In one embodiment, the groove pattern includes a plurality of concentric polygons 118 with a plurality of radial lines 120, as depicted in FIG. 1B.

  In one embodiment, the term “covalently bonded” means that atoms from the material 110 in the endpoint detection region 108 are cross-linked or shared with atoms from the cast homogeneous abrasive 102. Refers to a sequence that provides a chemical bond. Such covalent bonds are distinct from electrostatic interactions that can occur when a portion of the polishing pad is excised and replaced with an insertion region, such as a window insert. Covalent bonds are also distinguished from mechanical bonds, such as bonds through screws, nails, glue, or other adhesives. As will be described in detail below, the covalent bond connects the endpoint detection region precursor already disposed therein, as opposed to through the separate formation of the abrasive body and the later added insert. It can be achieved by curing the accompanying abrasive body precursor.

  In another embodiment, the material of the end point detection region is not entirely retracted relative to the back surface of the cast homogeneous abrasive. FIG. 2A illustrates a cross-sectional view of another polishing pad, according to an embodiment of the present invention. FIG. 2B illustrates a top view of the polishing pad of FIG. 2A, according to an embodiment of the invention.

  Referring to FIGS. 2A and 2B, the polishing pad 200 includes a cast homogeneous abrasive body 202. The cast homogeneous abrasive 202 has an abrasive surface 204 and a back surface 206 (note that the back surface 206 is depicted only in FIG. 2A). The end point detection region 208 is disposed in the cast homogeneous abrasive body 202. The end point detection region 208 is made of a material 210 different from the cast homogeneous abrasive 202. Material 210 is covalently bonded 212 with the material of the cast homogeneous abrasive body 202.

  In some embodiments, only a portion of the material 210 in the endpoint detection area 208 is retracted relative to the back surface 206 of the cast homogeneous abrasive body 202. For example, the material 210 of the endpoint detection region 208 has a first surface 214, a second surface 216, and a third surface 218. The second surface includes only the inner portion of the end point detection region 208 and is retracted by an amount D with respect to the back surface 206 of the cast homogeneous abrasive 202 and the third surface 218 of the end point detection region 208. Accordingly, the sidewall 220 of the end point detection region 208 remains along the interface 222 where the end point detection region 208 and the cast homogeneous abrasive body 202 meet.

  In one embodiment, holding the sidewalls 220 achieves a large range of covalent bonding between the endpoint detection region 208 and the cast homogeneous abrasive body 202 and increases the integrity of the polishing pad 200. In one embodiment, the second surface 216 is retracted by an amount D sufficient to accommodate an eddy current probe protruding from the mounting plate of the chemical mechanical polishing apparatus. In a specific embodiment, the recession depth D is about 70 mils (thousandths of an inch) below the surface 206.

  Referring to FIGS. 1A, 1B, 2A, and 2B, according to an embodiment of the present invention, the endpoint detection area (eg, area 108 or 208) is a locally transparent (LAT) area. In certain embodiments, the cast homogeneous abrasive is opaque while the LAT region is not opaque. In one embodiment, the cast homogeneous abrasive is opaque, at least in part, due to the inclusion of inorganic substances in the material used in its manufacture, as described below. In this embodiment, the LAT region is manufactured with the exclusion of inorganic materials and is substantially, if not completely, transparent to visible light, ultraviolet light, infrared light, or combinations thereof, for example. It is. In a specific embodiment, the inorganic material contained within the cast homogenous abrasive is an opacifying lubricant, while the LAT region does not contain any inorganic material and essentially contains an opacifying lubricant. do not do.

  In some embodiments, the LAT region is effectively transparent (ideal, for example, to position the polishing pad on the mounting board or to allow light transmission through the polishing pad for endpoint detection. Is completely transparent). However, although the LAT region cannot be manufactured or need not be manufactured to be completely transparent, the LAT region is still used to position the polishing pad on the mounting plate or to detect light for endpoint detection. There may be cases where it may be effective for transmission. For example, in one embodiment, the LAT region is less than 80% incident light within the 700-710 nanometer range, but is still suitable for acting as a window in the polishing pad. In certain embodiments, the aforementioned LAT region is impermeable to the slurry used in the chemical mechanical polishing operation.

  In one embodiment, referring again to FIGS. 1B and 2B, the endpoint detection areas 108 and 208 are LAT areas, respectively, and are visually transparent from a top view. In one embodiment, this visual transparency assists in mounting the polishing pad on a mounting board equipped with an eddy current detection probe. In FIG. 2B, the sidewall 220 is visible from this viewpoint, as depicted by the dashed rectangular shape.

  However, in another embodiment, the material of the endpoint detection area is opaque and therefore does not act to provide a locally transparent area. For example, FIGS. 3A and 3B illustrate cross-sectional views of other polishing pads according to another embodiment of the present invention.

  With reference to FIGS. 3A and 3B, polishing pad 300 (or 300 ′) includes a cast homogeneous abrasive body 302. The cast homogeneous abrasive body 302 has an abrasive surface 304 and a back surface 306. The end point detection region 308 (or 308 ′) is disposed in the cast homogeneous abrasive body 302. The end point detection region 308 (or 308 ′) is made of an opaque material 310 that is different from the cast homogeneous abrasive 302. The material 310 is covalently bonded 312 with the material of the cast homogeneous abrasive body 302.

  In one embodiment, referring to FIG. 3A, the material 310 of the endpoint detection region 308 is retracted relative to the back surface 306 of the overall cast homogeneous abrasive 302. In another embodiment, referring to FIG. 3B, only a portion of the material 310 in the endpoint detection region 308 ′ is retracted relative to the back surface 306 of the cast homogeneous abrasive 302, leaving the sidewall 320. In some embodiments, the endpoint detection area 308 (or 308 ′) is an opaque area having a hardness that is different from the hardness of the cast homogeneous abrasive 302. In a specific embodiment, the hardness of the end point detection region 308 (or 308 ') is higher than the hardness of the cast homogeneous abrasive 302. However, in an alternative embodiment, the end point detection region 308 (or 308 ') has a lower hardness than the cast homogeneous abrasive 302. In certain embodiments, the endpoint detection region 308 (or 308 ') is impermeable to the slurry used in the chemical mechanical polishing operation.

  The endpoint detection region 308 (or 308 ′) is made of opaque material 310, but the region is still for visually mounting the polishing pad 300 or 300 ′, respectively, on a mounting board equipped with an eddy current probe. Can be used. For example, in one embodiment, the absence of a grooved pattern on the first surface 304 of the endpoint detection area 308 (or 308 ′) is a visual indication of the location of the endpoint detection area 308 (or 308 ′) or Provide clues.

  In another aspect of the invention, a polishing pad for use with eddy current detection includes an endpoint detection region that is made of the same material as the rest of the polishing pad and is homogeneous. FIG. 4A illustrates a cross-sectional view of a polishing pad adapted for polishing a semiconductor substrate and for eddy current endpoint detection, according to an embodiment of the present invention. FIG. 4B illustrates a top view of the polishing pad of FIG. 4A, according to an embodiment of the invention.

  With reference to FIGS. 4A and 4B, polishing pad 400 includes a cast homogeneous abrasive body 402. The cast homogeneous abrasive 402 has an abrasive surface 404 and a back surface 406. The pattern of grooves 408 is disposed within the polishing surface 404. Each groove in the groove pattern has a bottom depth 410. The polishing pad 400 also includes an endpoint detection region 412 formed in the cast homogeneous polishing body 402. The endpoint detection region has a first surface 414 oriented with respect to the polishing surface 404 and a second surface 416 oriented with respect to the back surface 406. At least a portion of the first surface 414 is flush with the bottom depth 410 of the groove pattern, for example, by a depth D1. The second surface 416 is retracted into the cast homogeneous abrasive 402 with respect to the back surface 406 by an amount D2. In one embodiment, the second surface 416 is retracted by an amount D2 sufficient to accommodate an eddy current probe protruding from the mounting plate of the chemical mechanical polishing apparatus. In a specific embodiment, the recession depth D2 is approximately 70 mils (thousandths of an inch) below the surface 406. In some embodiments, the first surface 414 does not interfere with slurry movement during wafer polishing because at least a portion of the first surface 414 is flush with the bottom depth 410 of the groove pattern.

  In some embodiments, at least a portion of the first surface 414 interrupts the groove pattern 408 of the polishing surface 404. For example, in one embodiment, referring to FIG. 4A, the entire first surface 414 of the endpoint detection region 412 is essentially flush with the bottom depth 410 of the pattern of grooves 408. Thus, the pattern of grooves 408 is essentially interrupted in the endpoint detection region 412 because a single large groove is formed on the first surface 414 of the endpoint detection region 412. Referring again to FIG. 4B, the polished surface 404 of the cast homogeneous abrasive body 402 has a pattern of grooves disposed therein. In one embodiment, the groove pattern includes a plurality of concentric polygons 418 with a plurality of radial lines 420. However, in the end point detection area 412, the pattern is interrupted by the absence of a groove.

  Therefore, a visual indicator of the location of the end point detection region 412 is provided even if the end point detection region 412 is made of the same material as the cast homogeneous abrasive 402. In a specific embodiment, the cast homogeneous abrasive 402, including the endpoint detection area 408, is opaque, but the interruption in the groove pattern is for mounting on a mounting board equipped with an eddy current detection system. , Used for visual determination of the location of the endpoint detection area 408.

  In another embodiment, the endpoint detection region essentially has a second groove pattern having a depth that is coplanar with the bottom depth of the groove pattern disposed within the polishing surface of the polishing pad. For example, FIG. 5A illustrates a cross-sectional view of another polishing pad, according to an embodiment of the present invention. FIG. 5B illustrates a top view of the polishing pad of FIG. 5A, according to an embodiment of the invention.

  Referring to FIGS. 5A and 5B, polishing pad 500 includes a cast homogeneous abrasive body 502. The cast homogeneous abrasive 502 has a polishing surface 504 and a back surface 506. A groove pattern 508 is disposed within the polishing surface 504. Each groove in the groove pattern has a bottom depth 510. The polishing pad 500 also includes an endpoint detection region 512 formed in the cast homogeneous abrasive body 502. The endpoint detection region has a first surface 514 oriented with respect to the polishing surface 504 and a second surface 516 oriented with respect to the back surface 506. At least a portion of the first surface 514 is flush with the bottom depth 510 of the groove pattern, for example, by a depth D1. The second surface 516 is retracted into the cast homogeneous abrasive 502 with respect to the back surface 506 by an amount D2. In one embodiment, the second surface 516 is retracted by an amount D2 sufficient to accommodate an eddy current probe protruding from the mounting plate of the chemical mechanical polishing apparatus. In a specific embodiment, the recession depth D2 is approximately 70 mils (thousandths of an inch) below the surface 506.

  In some embodiments, at least a portion of the first surface 514 interrupts the pattern of grooves 508 in the polishing surface 504. For example, in one embodiment, referring to FIG. 5A, the first surface 514 of the endpoint detection region 512 is essentially the bottom depth (eg, depth D1) of the pattern of grooves 508 disposed within the polishing surface 504. A pattern of second grooves 518 with a coplanar depth. However, the pattern of grooves 508 in the polishing surface 504 and the pattern of second grooves 518 in the endpoint detection area 512 are interrupted by changes in the spacing 520. For example, the individual grooves of both the pattern of grooves 508 and the pattern of second grooves 518 are separated by a certain width W1, and the pattern of second grooves 518 is the first groove 508 by a distance W2 that exceeds the width W1. Offset from the pattern.

  Referring again to FIG. 5B, the polished surface 504 of the cast homogeneous abrasive body 502 has a pattern of grooves disposed therein. In one embodiment, the groove pattern includes a plurality of concentric polygons 522 with a plurality of radial lines 524. However, in the end point detection region 512, the pattern is interrupted around the pattern of the second groove 518. Therefore, a visual indicator of the location of the end point detection region 512 is provided even if the end point detection region 512 is made of the same material as the cast homogeneous abrasive body 502. In a specific embodiment, the cast homogeneous abrasive body 502 including the endpoint detection area 508 is opaque, but the interruption in the groove pattern is not suitable for mounting on a mounting board equipped with an eddy current detection system. Used for visual determination of the location of the detection area 508.

  The use of interruptions in the groove pattern for visual determination of the location of the end point detection area to be mounted on a mounting board equipped with an eddy current detection system, the offset in the groove pattern, as described above, the polishing pad However, the present invention is not limited to the embodiment showing the location of the end point detection area on the back side. In another embodiment, additional grooves are included on the polishing surface to trace the contour of the location of the detection area on the back side of the polishing pad. In another embodiment, the change in groove width is used on the polishing surface to indicate the location of the detection area on the back side of the polishing pad. In another embodiment, the change in groove pitch is used on the polishing surface to indicate the location of the detection area on the back side of the polishing pad. In another embodiment, two or more of the aforementioned features are included on the polishing surface to indicate the location of the detection area on the back side of the polishing pad.

  According to an embodiment of the present invention, the cast homogeneous abrasive body is made of a thermosetting closed cell polyurethane material. In certain embodiments, the term “homogeneous” is used to indicate that the composition of the thermoset closed cell polyurethane material is consistent throughout the composition of the abrasive body. For example, in certain embodiments, the term “homogeneous” excludes polishing pads made of impregnated felt or composition (composite) of multiple layers of different materials, for example. In certain embodiments, the term “thermoset” refers to a polymer material that irreversibly cures, eg, a polymer material in which a precursor of the material irreversibly changes upon curing into an infusible insoluble polymer network. Used for. For example, in certain embodiments, the term “thermosetting” excludes polishing pads made of, for example, “thermoplastic” materials or “thermoplastics” (the materials return to liquid when heated, When fully cooled, it consists of a polymer that freezes to a very glassy state). Polishing pads made from thermoset materials are typically made from low molecular weight precursors reacting to form a polymer in a chemical reaction, while pads made from thermoplastic materials are typically Note that in particular, the existing polymer is heated and the polishing pad is manufactured by phasing so that it is formed in a physical process. In certain embodiments, the term “cast” is used to indicate that a cast homogeneous abrasive body is formed in a forming mold, as described in more detail below.

  In some embodiments, the abrasive body is opaque. In one embodiment, the term “opaque” is used to indicate a material that transmits no more than about 10% visible light. In one embodiment, the cast homogenous abrasive body contains, for the most part or in total, the inclusion of opacifying lubricant throughout the homogeneous thermoset closed cell polyurethane material of the cast homogenous abrasive body (e.g., As an additional component in it). In a specific embodiment, the opacifying lubricant is a material such as boron nitride, cerium fluoride, graphite, fluorinated graphite, molybdenum sulfide, niobium sulfide, talc, tantalum sulfide, tungsten disulfide, or Teflon. It is not limited to.

  In some embodiments, the cast homogeneous abrasive body includes a porogen. In one embodiment, the term “porogen” is used to indicate a micro or nanoscale spherical particle with a “hollow” center. The hollow center is not filled with a solid material, but rather may include a gaseous or liquid core. In one embodiment, the cast homogeneous abrasive body is pre-foamed and gasified as a porogen throughout the homogeneous thermoset closed cell polyurethane material of the cast homogeneous abrasive body (eg, as an additional component therein). EXPANCEL filled with In a specific embodiment, EXPANCEL is filled with pentane.

  The size of the cast homogeneous abrasive can vary depending on the application. Nevertheless, certain parameters can be used to make a polishing pad containing such a cast homogeneous abrasive body that is compatible with conventional processing equipment or conventional chemical mechanical processing operations. For example, according to an embodiment of the present invention, the cast homogeneous abrasive body has a thickness in the range of about 0.075 inches to 0.130 inches, for example in the range of about 1.9-3.3 millimeters. . In one embodiment, the cast homogeneous abrasive 202 has a diameter in the range of about 20 inches to 30.3 inches, for example in the range of about 50-77 centimeters, and possibly in the range of about 10 inches to 42 inches. For example, having a range of about 25-107 centimeters. In one embodiment, the cast homogenous abrasive body has a pore density in the range of about 18% -30% total void volume, possibly in the range of about 15% -35% total void volume. In one embodiment, the cast homogeneous abrasive has a closed cell type with a certain porosity. In one embodiment, the cast homogeneous abrasive body has a pore size of about 40 microns diameter, but may be smaller, eg, about 20 microns diameter. In one embodiment, the cast homogeneous abrasive has a compressibility of about 2.5%. In one embodiment, the cast homogeneous abrasive has a density in the range of about 0.70-0.90 grams per cubic centimeter, or in the range of about 0.95-1.05 grams per cubic centimeter.

  For eddy current detection, the removal rate of various films using a polishing pad containing a cast homogeneous polishing body can vary depending on the polishing tool, slurry, conditioning, or polishing scheme used. However, in one embodiment, the cast homogeneous abrasive exhibits a copper removal rate in the range of about 30-900 nanometers per minute. In one embodiment, the cast homogeneous abrasive exhibits an oxide removal rate in the range of about 30-900 nanometers per minute, as described herein.

  As previously mentioned, a polishing pad adapted for eddy current detection can be manufactured in a casting process. In certain embodiments, a casting process may be used to produce a polishing pad with an endpoint detection region that is made of a material different from the rest of the polishing pad. For example, FIGS. 6A-6J illustrate cross-sectional views of various process operations in the manufacture of a polishing pad adapted for eddy current endpoint detection for polishing a semiconductor substrate, according to an embodiment of the present invention.

  With reference to FIGS. 6A-6D, a method of manufacturing a polishing pad includes first forming a partially cured endpoint detection region precursor. For example, referring to FIGS. 6A and 6B, the first forming mold 602 is filled with the precursor mixture 604 and the lid 606 of the first forming mold 602 is placed on top of the mixture 604. In certain embodiments, with lid 606 in place, mixture 604 is heated under pressure and partially cured body 608 (eg, formed throughout mixture 604 as depicted in FIG. 6C). At least some chain extension and / or cross-linking). Upon removal of the partially cured body 608 from the first forming mold 602, a partially cured endpoint detection region precursor 608 is provided, as depicted in FIG. 6D.

  In some embodiments, the partially cured endpoint detection region precursor 608 is formed by mixing a urethane prepolymer with a curing agent. In one embodiment, the partially cured endpoint detection area precursor 608 ultimately provides a locally transparent (LAT) area within the polishing pad. The LAT region is compatible with a variety of endpoint detection techniques and may be made of a material suitable for inclusion in a polishing pad manufactured by a casting process. For example, the partially cured endpoint detection region precursor 608 is formed by first mixing an aromatic urethane prepolymer with a curing agent. In another embodiment, the opaque region is formed by including an opacifier in the mixture. In either case, the resulting mixture is then partially cured in a first forming mold to form a cast gel.

  Referring to FIG. 6E, the partially cured endpoint detection area precursor 608 is positioned on the receiving area 614 of the lid 612 of the second forming mold 610. A polishing pad precursor mixture 616 is formed in the second forming mold 610. According to an embodiment of the invention, the polishing pad precursor mixture 616 includes a polyurethane prepolymer and a curing agent.

  In certain embodiments, the polishing pad precursor mixture 616 is ultimately used to form a cast homogeneous abrasive body composed of a thermoset closed cell polyurethane material. In one embodiment, the polishing pad precursor mixture 616 is ultimately used to form a hard pad and only a single type of curing agent is used. In another embodiment, the polishing pad precursor mixture 616 is ultimately used to form a soft pad, and a combination of primary and secondary curing agents is used. For example, in a specific embodiment, the prepolymer includes a polyurethane precursor, the primary curing agent includes an aromatic diamine compound, and the secondary curing agent includes an ether linkage. In certain embodiments, the polyurethane precursor is an isocyanate, the primary curing agent is an aromatic diamine, and the secondary curing agent is not limited to polyoxytetramethylene glycol, amino functionalized glycol, or amino functional Hardener such as modified polyoxypropylene. In some embodiments, the prepolymer, primary curing agent, and secondary curing agent have an approximate molar ratio of 100 parts by weight prepolymer, 85 parts by weight primary curing agent, and 15 parts by weight secondary curing agent. It should be understood that the ratio variation can be used to provide a variable hardness value to the polishing pad or based on the specific properties of the prepolymer and the first and second curing agents. In certain embodiments, the mixing further includes mixing the opacifying lubricant with a prepolymer, a primary curing agent, and a secondary curing agent. In certain embodiments, the opacifier is a material such as, but not limited to, boron nitride, cerium fluoride, graphite, graphite fluoride, molybdenum sulfide, niobium sulfide, talc, tantalum sulfide, tungsten disulfide, or Teflon.

  In a specific embodiment, the cast homogeneous abrasive body comprises: (a) AIRTHANE 60D: an aromatic urethane prepolymer such as polytetramethylene glycol-toluene diisocyanate; (b) EXPANCELDE 40: an acrylonitrile / acrylate copolymer with isobutene or pentane filler. (C) Lubricants and bleach fillers, (d) Terathane 2000: polyols such as polyoxytetramethylene glycol, and (e) catalysts such as ABCO1027, and (f) CURENE 107: thioether aromatic diamines, etc. A curing agent, (g) a thermal stabilizer such as Irgastab PUR68, and (g) Tin to form a substantially opaque blunt yellow thermoset polyurethane having a substantially uniform microcell closed cell structure It is prepared by reacting a UV absorber such as Vin213. In one embodiment, EXPANCEL is filled with gas, and the average pore size of each EXPANCEL unit is in the range of about 20 to 40 microns.

  Referring to FIG. 6F, the partially cured endpoint detection region precursor 608 is moved into the polishing pad precursor mixture 616 by lowering the lid 612 of the second forming mold 610. In some embodiments, the partially cured endpoint detection region precursor 608 is moved to the bottom surface of the second forming template 610, as depicted in FIG. 6F. In some embodiments, a plurality of grooves are formed in the lid 612 of the forming mold 612. The plurality of grooves are used to indent the groove pattern on the polishing surface of the polishing pad formed in the forming mold 610. The embodiments described herein that describe moving the partially cured endpoint detection region precursor into the polishing pad precursor mixture by lowering the lid of the forming mold are described below. It should be understood that it is only necessary to achieve the lid and base together. This is because, in some embodiments, the base of the forming mold is raised toward the lid of the forming mold, while in other embodiments, the lid of the forming mold is simultaneously raised toward the lid. As it is done, it is lowered towards the base of the forming template.

Referring to FIG. 6G, the polishing pad precursor mixture 616 and the partially cured endpoint detection region precursor 608 are heated and cured endpoints under pressure (eg, with the lid 612 in place). A cast homogeneous abrasive 620 is provided that is covalently bonded to the detection region precursor 622. Referring to FIG. 6H, the polishing pad (or polishing pad precursor if further curing is required) is removed from the mold 610 and cured into a cast homogeneous abrasive 620 disposed therein. An endpoint detection region precursor 622 is provided. Note that further curing through heating may be desirable and may be performed by placing the polishing pad in a furnace and heating. In either method, a polishing pad is ultimately provided, and the cast homogeneous polishing body 620 of the polishing pad comprises a polishing surface (top grooved surface in FIG. 6H) and a back surface (bottom flat surface in FIG. 6H). ). In certain embodiments, heating within the forming mold 610 encapsulates the mixture 616 within the forming mold 610 at a temperature in the range of about 200-260 ° F. and a pressure in the range of about 2-12 pounds per square inch. Finally, referring to FIGS. 6I and 6J, the cured endpoint detection region precursor 622 is the backside of the cast homogeneous abrasive 620. Retracted against the surface. Retracting provides the polishing pad with an endpoint detection region 624 that is disposed within the cast homogeneous abrasive body 620 and is covalently coupled to the cast homogeneous abrasive body. For example, polishing pads that can be obtained in the manner described above can include, but are not limited to, the polishing pads described in connection with FIGS. 1A and 1B, 2A and 2B, 3A and 3B.

  According to some embodiments of the invention, retracting the cured endpoint detection region precursor 622 is performed by digging out a portion of the cured endpoint detection region precursor 622. In one embodiment, the entire endpoint detection area 624 is retracted relative to the back surface of the cast homogeneous abrasive body 620 as depicted in FIG. 6I and described in connection with FIGS. 1A, 1B, and 3A. It is done. In another embodiment, however, only the inner portion of the endpoint detection region 624 is depicted on the back surface of the cast homogeneous abrasive body as depicted in FIG. 6J and described in connection with FIGS. 2A, 2B, and 3B. Retreated against.

  In another aspect, a casting process can be used to produce a polishing pad with an endpoint detection region that is made of a different material than the rest of the polishing pad. However, the material used for the endpoint detection area can be introduced into the casting process on a separate support structure that needs to be accommodated in the casting process. For example, FIGS. 6K-6T illustrate cross-sectional views of various process operations in the manufacture of a polishing pad adapted for eddy current endpoint detection for polishing a semiconductor substrate, according to an embodiment of the present invention. .

  Referring to FIGS. 6K-6O, a method of manufacturing a polishing pad first includes forming a partially cured endpoint detection region precursor on a support structure. For example, referring to FIGS. 6K and 6L, the support structure 699 is placed inside the first forming mold 602. According to an embodiment of the invention, the support structure 699 has a conformal size with the bottom of the first forming mold 602. In one embodiment, the support structure 699 is made of a non-flexible material, for example, a brittle material such as a hard epoxy board. In one embodiment, the support structure 699 is made of a material suitable to withstand a temperature of about 300 ° F. In one embodiment, the support structure 699 is suitable for withstanding a high heat balance because, in a specific embodiment, the support structure 699 is recycled for repeated use in the casting process illustrated in FIGS. 6K-6T. Made of material. In certain embodiments, the support structure 699 is comprised of a thermally insulating material to avoid any heat transfer through the support structure 699 during the casting process. In certain embodiments, the support structure 699 is comprised of a chemically inert material and does not covalently bond with the polyurethane material during the curing process. In certain embodiments, the support structure 699 is made of a material that exhibits little or no outgassing upon heating.

  Referring to FIGS. 6M-6O, the first forming mold 602 is filled with the precursor mixture 604 above the support structure 699, and the lid 606 of the first forming mold 602 is placed on top of the mixture 604. . In certain embodiments, with lid 606 in place, mixture 604 is heated under pressure and partially cured body 608 (eg, depicted in FIG. 6N) disposed on support structure 699. As such, it provides at least some chain extension and / or cross-linking formed throughout the mixture 604. In response to removal of the partially cured body 608 and the associated support structure 699 from the first forming mold 602, a partially cured endpoint detection region precursor 608 is depicted in FIG. 6O. To the support structure 699. In certain embodiments, the polymer film is adhered to the top surface of the support structure 699 by a piece of double-sided tape prior to adding the mixture 604 to the first forming mold 602. Thus, in some embodiments, the partially cured body 608 is coupled to the support structure 699 by a polymer membrane and a piece of double-sided tape.

  With reference to FIGS. 6P and 6Q, the partially cured endpoint detection region precursor 608 and the associated support structure 699 are positioned within the receiving region 614 ′ of the lid 612 ′ of the second forming mold 610. In some embodiments, the polymer film is disposed between the partially cured endpoint detection region precursor 608 and the support structure 699, for example by a first piece of double-sided tape, and a second piece of double-sided tape. Are used to connect the support structure 699 to the surface of the receiving area 614 ′ of the lid 612 ′. A polishing pad precursor mixture 616 is formed in the second forming mold 610. According to an embodiment of the invention, the polishing pad precursor mixture 616 includes a polyurethane prepolymer and a curing agent.

  Referring to FIG. 6R, the partially cured endpoint detection region precursor 608 is supported by the support structure 699 while lowering the lid 612 ′ of the second forming mold 610 to lower the polishing pad precursor mixture 616. Moved in. In some embodiments, the partially cured endpoint detection region precursor 608 is moved to the bottommost surface of the second forming mold 610. The polishing pad precursor mixture 616 and the partially cured endpoint detection region precursor 608, and thus the support structure 699, are heated under pressure (eg, with the lid 612 'in place) to provide an endpoint detection region. A cast homogeneous abrasive 620 that is cross-linked with the precursor 622 is provided.

  Referring to FIG. 6S, the polishing pad (or polishing pad precursor if further curing is required) is removed from the mold 610 and cast with a cured endpoint detection region precursor 622 disposed therein. A homogenized abrasive body 620 is provided. However, in certain embodiments, the support structure 699 remains coupled to the cured endpoint detection region precursor 622 after removal from the forming template 610, as depicted in FIG. 6S. Note that further curing through heating may be required and can be done by placing the polishing pad in a furnace and heating. In either method, a polishing pad is ultimately provided, and the cast homogeneous polishing body 620 of the polishing pad comprises a polishing surface (top grooved surface in FIG. 6S) and a back surface (bottom flat surface in FIG. 6S). ), As well as a support structure 699. Thus, in certain embodiments, the support structure 699 is removed to provide a polishing pad, for example, by removing the support structure 699 and the joining double-sided tape from the cured endpoint detection region precursor 622. There is a need. In one embodiment, the support structure 699 is removed, and subsequently the cured endpoint detection region precursor 622 is retracted and applied to the polishing pad as described above in connection with FIGS. 6I and 6J. Provides a detection area.

  Referring to FIG. 6T, in another embodiment, the support structure 699 remains coupled to the receiving area 614 ′ of the lid 612 ′ in response to removal of the polishing pad from the mold 610. That is, the support structure 699 peels from the endpoint detection region precursor 620 when the lid 612 ′ is lifted from the forming mold 610. In certain embodiments, the support structure 699 is easily removed by pulling the support structure 699 from the receiving area 614 '. However, in another embodiment, the support structure 699 may prove difficult to remove from the lid 612 '. Thus, in one embodiment, an opening or vent 690 is provided in the lid 612 '. In response to removal of the lid 612 'from the forming mold 610, air or inert gas may be forced through the openings 690 to eject the support structure 699 from the receiving area 614'. In a specific embodiment, support structure 699 is then reused in a subsequent casting process.

  In another aspect, the partially cured endpoint detection region precursor can include a sacrificial layer, and the retreat is performed by removing the sacrificial layer. For example, FIGS. 7A-7C illustrate cross-sectional views of various process operations in the manufacture of a polishing pad adapted for eddy current endpoint detection for polishing a semiconductor substrate, according to an embodiment of the present invention.

  Referring to FIG. 7A, the partially cured endpoint detection region precursor 708 has a partially cured endpoint detection region precursor 708 thereon by lowering the lid 612 of the forming mold 610. Inserted into the polishing pad precursor mixture 616. However, in some embodiments, unlike the partially cured endpoint detection region precursor 608, the partially cured endpoint detection region precursor 708 includes a sacrificial layer 709 disposed thereon. Thus, the partially cured endpoint detection region precursor 708 is not inserted alone into the polishing pad precursor mixture 616 and then moved toward the bottom surface of the forming mold 610. Rather, the sacrificial layer 709 is coupled to the partially cured endpoint detection region precursor 708 prior to placement of the endpoint detection region precursor 708 on the lid 612 of the forming mold 610. Together, the partially cured endpoint detection region precursor 708 and sacrificial layer 709 are then moved toward the bottom surface of the forming mold 610, as depicted in FIG. 7A. Thus, the sacrificial layer 709 is located between the bottom of the forming mold and the partially cured endpoint detection region precursor 708. In one embodiment, the sacrificial layer 709 is composed of a composite material that includes a layer of Mylar film as a component.

  Referring to FIG. 7B, the polishing pad precursor mixture 616 and the partially cured endpoint detection region precursor 708 are heated under pressure (eg, with the lid 612 in place) to provide an endpoint detection region 722. A cast homogeneous abrasive body 620 is provided that is covalently coupled to Referring to FIG. 7C, the polishing pad is removed from the mold 610 to provide the cast homogeneous polishing body 620 with an endpoint detection region 722 and a sacrificial layer 709 disposed therein. According to an embodiment of the present invention, retreating the eddy current detection region of the polishing pad is accomplished by removing the sacrificial layer 709, as depicted in FIG. 7D. In one embodiment, the entire endpoint detection area 722 is therefore retracted relative to the back surface of the cast homogeneous abrasive 620, as also depicted in FIG. 7D.

  According to certain embodiments of the invention, the endpoint detection region (eg, 624 in FIG. 6I or 722 in FIG. 7D) is as described above and in connection with FIGS. 1A and 1B, 2A and 2B, 3A and 3B. It consists of a different material from the cast homogeneous abrasive. For example, in one embodiment, endpoint detection region 624 or 722 is a locally transparent (LAT) region, as described in connection with FIGS. 1A, 1B and 2A, 2B. In one embodiment, the endpoint detection area 624 or 722 is an opaque area having a hardness that is different from the hardness of the cast homogeneous abrasive 620, as described in connection with FIGS. 3A and 3B. In some embodiments, the cast homogeneous abrasive 620 is comprised of a thermoset closed cell polyurethane material. In some embodiments, the polished surface 620 of the cast homogeneous abrasive body includes a pattern of grooves disposed therein and formed from the lid of the second forming mold 610.

  As briefly described above, in some embodiments, the endpoint detection region 624 (or 722) and the cast homogeneous abrasive 620 can have different hardnesses. For example, in one embodiment, the cast homogeneous abrasive 620 has a hardness that is less than the hardness of the endpoint detection region 624. In a specific embodiment, the cast homogenous abrasive 620 has a hardness in the range of about 20-45 Shore D, while the endpoint detection region 624 has a hardness of about 60 Shore D. The hardness can vary, but the covalent and / or cross-linking between the endpoint detection region 624 and the cast homogeneous abrasive 620 can still be extensive. For example, according to an embodiment of the present invention, the hardness difference between the cast homogeneous abrasive 620 and the end point detection region 624 is greater than or equal to Shore D10, but between the cast homogeneous abrasive 620 and the end point detection region 624. The degree of covalent and / or cross-linking is substantial.

  The dimensions of the polishing pad and the endpoint detection area disposed therein can vary according to the desired application. For example, in one embodiment, the polishing pad is manufactured to accommodate eddy current probes, and the cast homogeneous abrasive 620 is circular with a diameter in the range of about 75-78 centimeters while endpoint detection. Region 624 has a length in the range of about 4-6 centimeters along the radial axis of the cast homogeneous abrasive 620, a width in the range of about 1-2 centimeters, and the cast homogeneous abrasive 620 Is located within the range of about 16-20 centimeters from the center of

  With respect to vertical positioning, the location of the endpoint detection region within the polishing body can be selected for a particular application and can be the result of the formation process. For example, positioning and achievable accuracy by including an endpoint detection area within the polishing body via a casting process, for example, the polishing pad is trimmed after formation and a window insert is added after the polishing pad is formed. Can be adjusted to a much greater extent than the process being performed. In some embodiments, as described above, by using a casting process, the endpoint detection region 624 is cast so that the bottom surface of the grooved surface of the cast homogeneous abrasive 620 is flush with the bottom of the valley. It is contained in the polishing body 620. In a specific embodiment, the end point detection region 624 includes the cast homogeneous abrasive body 620 and the end point detection region 624 so that it is flush with the bottom of the trough of the grooved surface of the cast homogeneous abrasive body. Throughout the life of the polishing pad manufactured from the endpoint detection region 624, it does not interfere with the CMP processing operation.

  As mentioned above, a polishing pad adapted for eddy current detection can be manufactured in a casting process. However, the polishing pad need not include LAT or other separate and different material regions. 8A-8F illustrate cross-sectional views of various process operations in the manufacture of a polishing pad polishing pad adapted for eddy current endpoint detection to polish a semiconductor substrate, according to an embodiment of the present invention. .

  Referring to FIG. 8A, a method of manufacturing a polishing pad includes forming a polishing pad precursor mixture 616 in a forming mold 610. With reference to FIGS. 8A and 8B, the lid 612 of the forming mold 610 is positioned in the polishing pad precursor mixture 616. The lid 612 includes a pattern of grooves 618 disposed thereon. The pattern of grooves 618 has a break region 614, which is different or somewhat separated from the majority of grooves 618, as will be described in more detail below.

  Referring to FIG. 8C, the polishing pad precursor mixture 616 provides a heated and cast homogeneous abrasive 620. Referring to FIG. 8D, the cast homogeneous abrasive 620 is removed from the forming mold 610 to provide a polishing pad (or precursor to the polishing pad if further heating or curing is required after the casting process). . A polishing pad consisting of a cast homogeneous abrasive 620 includes a polishing surface 822 and a back surface 824. According to one embodiment of the present invention, a pattern of grooves 618, including the interrupting region 614, from the lid 612 of the forming mold 610 is disposed within the polishing surface 822, as depicted in FIG. 8D. The pattern of grooves disposed within the polishing surface 822 has a bottom depth 826. In some embodiments, the cast homogeneous abrasive 620 is comprised of a thermoset closed cell polyurethane material.

  With reference to FIGS. 8E and 8F, an endpoint detection region 830 is provided in the cast homogeneous abrasive body 620. The endpoint detection region has a first surface 832 oriented relative to the polishing surface 822 and a second surface 834 oriented relative to the back surface 620 of the cast homogeneous abrasive. At least a portion of the first surface 832 is flush with the bottom depth 826 of the groove pattern. For example, in one embodiment, the entire first surface 832 is flush with the bottom depth 826 of the groove pattern, as depicted in FIG. 8E. In addition, the second surface 834 is retracted into the cast homogeneous abrasive 620 relative to the back surface 824, as also depicted in FIG. 8E. In some embodiments, providing the endpoint detection region 830 is performed by digging out a portion of the cast homogeneous abrasive 620. In certain embodiments, the cast homogeneous abrasive 620 that includes the endpoint detection region 830 is opaque.

  According to certain embodiments of the invention, as described above, the polishing surface 822 includes interrupted regions of the groove pattern. The interruption area corresponds to the interruption area 614 in the lid 612 of the forming mold 610. In one embodiment, the interrupt region 614 is generally flat and planar with respect to the bottom of the lid 612, as depicted in FIGS. 8A and 8E. Thus, the entire first surface 832 of the endpoint detection region 830 is essentially the same as the bottom depth 826 of the pattern of grooves in the polishing surface 822, as described in connection with the polishing pad of FIGS. 4A and 4B. It is a plane. However, in an alternative embodiment, the first surface of the endpoint detection region 830 is essentially flush with the bottom depth of the pattern of grooves disposed within the polishing surface 822 of the cast homogeneous abrasive body 820. It includes a pattern of second grooves 850 having a depth. Such an alternative embodiment is depicted in FIG. 8F. A polishing pad according to this embodiment has been described above in connection with FIGS. 5A and 5B. In a specific embodiment, the individual grooves of both the groove pattern (of the polishing surface 822) and the second groove pattern (of the interrupt region) are also associated with those described above in connection with FIGS. 5A and 5B. As described above, the second groove pattern is offset by a certain width and is offset from the first groove pattern by a distance greater than the width.

  In another aspect of the invention, the endpoint detection region in the cast homogeneous abrasive is formed by removing the sacrificial layer. For example, FIGS. 9A-9F illustrate the manufacture of a polishing pad with an endpoint detection region provided therein by removing a sacrificial layer embedded within a cast homogeneous polishing body, according to an embodiment of the present invention. 2 illustrates cross-sectional views of various process operations.

  Referring to FIG. 9A, the sacrificial layer 709 is disposed at the bottom of the forming mold 610. For example, in one embodiment, the sacrificial layer 709 is inserted into the forming mold prior to the addition of the polishing pad component to the mold. In a specific embodiment, the sacrificial layer 709 comprises a layer of Mylar film. Referring to FIG. 9B, the polishing pad precursor mixture is dispensed into the forming mold 610 over the sacrificial layer 709. Referring to FIG. 9C, with the lid 612 in place in the forming mold 610, the polishing pad precursor mixture 616 is heated and cast into a homogeneous polishing as described in connection with FIG. 8C. A body 620 is provided. However, the sacrificial layer 709 located at the bottom of the forming mold 610 remains during the casting of 620.

  Referring to FIG. 9D, the cast homogeneous abrasive 620 is removed from the forming mold and a polishing pad with a sacrificial layer 709 disposed therein (or if further heating or curing is required after the casting process). , A precursor to the polishing pad). With reference to FIGS. 9E and 9F, an endpoint detection region 924 is provided in the cast homogeneous abrasive 620 in response to removal of the sacrificial layer 709. Thus, according to an embodiment of the present invention, retreating the eddy current detection region of the polishing pad is accomplished by removing a sacrificial layer 709 that is coplanar with the back surface of the polishing pad. In one embodiment, the entire endpoint detection area 924 is then retracted relative to the back surface of the cast homogeneous abrasive 620, as depicted in FIGS. 9E and 9F. In one embodiment, the entire upper surface 950 of the endpoint detection area 924 is retracted and flat as depicted in FIG. 9E. However, in another embodiment, a second set of grooves 952 that are interrupted from the grooves of the 620 polishing surface are disposed on the upper surface of the endpoint detection region 924, as depicted in FIG. 9F.

  In yet another embodiment, the receding area for the polishing pad can be manufactured by installing or incorporating raised features at the bottom of the mold used to form the polishing pad. For example, referring again to FIGS. 9A-9C, instead of the sacrificial layer 709, the blackened region can be a permanent or semi-permanent feature embedded in the forming mold 610. That is, the feature does not transfer with the manufactured polishing pad, as opposed to the sacrificial layer 709 transferred from the mold with the manufactured polishing pad (eg, as described in connection with FIG. 9D). In such cases, in one embodiment, a polishing pad consisting of a homogeneous abrasive 620 such as that shown in FIGS. 9E and 9F may be used to remove the sacrificial layer intermediately (as described differently in connection with FIG. 9D). ) Directly in the forming mold. In another embodiment, permanent or semi-permanent features embedded in the forming mold are used to produce polishing pads such as those described in connection with FIGS. 1A, 2A, 3A, and 3B. Used with heavy material pad manufacturing.

  The polishing pad described herein may be suitable for using a chemical mechanical polishing apparatus equipped with an eddy current endpoint detection system. For example, FIG. 10 illustrates an isometric side view of a polishing apparatus that is compatible with a polishing pad adapted for eddy current endpoint detection, according to an embodiment of the present invention.

  Referring to FIG. 10, the polishing apparatus 1000 includes a mounting plate 1004. The top surface 1002 of the mounting plate 1004 can be used to support a polishing pad for eddy current endpoint detection. The mounting plate 1004 may be configured to provide spindle rotation 1006 and slider vibration 1008. Sample carrier 1010 is used, for example, to hold semiconductor wafer 1011 in place during polishing of the semiconductor wafer with a polishing pad. The sample carrier 1010 is further supported by a suspension mechanism 1012. A slurry feed 1014 is included to provide slurry to the surface of the polishing pad prior to and during polishing of the semiconductor wafer.

  In one aspect of the invention, a polishing pad adapted for eddy current endpoint detection is provided for use with a polishing apparatus similar to polishing apparatus 1000. For example, FIG. 11 illustrates a cross-sectional view of a polishing apparatus with an eddy current endpoint detection system and a polishing pad compatible with the eddy current endpoint detection system, according to an embodiment of the present invention.

  Referring to FIG. 11, the polishing station 1000 includes a rotatable mounting board 1004 on which a polishing pad 1118 is installed. The polishing pad 1118 provides a polishing surface 1124. At least a portion of the polishing surface 1124 can have a groove 1128 for holding the slurry. The polishing station 1000 also includes a polishing pad conditioner that can maintain the state of the polishing pad so as to effectively polish the substrate. During a polishing operation, chemical mechanical polishing slurry 1130 is supplied to the surface of polishing pad 1118 by a slurry supply port or a combined slurry / rinse arm 1014. The substrate 1011 is held against the polishing pad 1118 by the carrier head 1010. The carrier head 1010 is suspended from a support structure such as a turntable and is connected to a carrier head rotation motor by a carrier drive shaft 1136 so that the carrier head can rotate about an axis 1138.

  The recess 1140 is formed in the mounting board 1004, and the in-situ monitoring module 1142 is housed in the recess 1140. The in-situ monitoring module 1142 may include an in-situ eddy current monitoring system with a core 1144 positioned within the recess 1140 and rotating with the mounting board 1004. The drive and sense coil 1146 is wound around the core 1144 and connected to the controller 1150. In operation, the vibrator excites the drive coil and generates an oscillating magnetic field 1148 that extends through the body of the core 1144. At least a portion of the magnetic field 1148 extends toward the substrate 1011 through the polishing pad 1118. If a metal layer is present on the substrate 1011, the oscillating magnetic field 1148 will generate eddy currents.

  Eddy currents generate a magnetic flux in a direction opposite to the induced electric field, and this magnetic flux induces a reverse current in the primary or sensing coil in the direction opposite to the drive current. The resulting current change can be measured as a coil impedance change. As the thickness of the metal layer changes, the resistance of the metal layer changes. Thus, the eddy current and the strength of the magnetic flux induced by the eddy current also change, resulting in a change in the impedance of the primary coil. By monitoring these changes, for example, by measuring the amplitude of the coil current or by measuring the phase of the coil current relative to the phase of the drive coil current, the eddy current sensor monitor can detect the thickness of the metal layer. Changes can be monitored.

  Referring again to FIG. 11 in accordance with an embodiment of the present invention, once the polishing pad 1118 is secured to the mounting plate 1004, the thin section is flat with the recess 1140 in the plate and the top surface of the mounting plate 1004. It fits over a portion of the core and / or coil that protrudes beyond. By positioning the core 1142 closer to the substrate 1112, the magnetic field is less diffused and the spatial resolution can be improved. Assuming that the polishing pad 1011 is not used with an optical endpoint monitoring system, in one embodiment, the entire polishing layer, including the portion covering the recess, can be opaque. However, in another embodiment, the portion covering the recess is transparent and assists in positioning the polishing pad on the mounting board.

  According to certain embodiments of the present invention, the problem addressed herein is that the sensor is raised above the plane of the mounting plate by about 0.070 inches so that it can be brought to an optimum distance from the wafer surface. For example, the eddy current end point detection hardware includes a sensor that performs the above process. However, this situation can create several problems in the design and performance of the polishing pad, whereas embodiments of the present invention can provide an advantageous solution. In one embodiment, the polishing pad is typically designed to accommodate an eddy current sensor by a recess formed in the back surface of the polishing pad. In a specific embodiment, an approximately 0.080 inch deep recess in the polishing pad is used for this purpose.

  In one aspect of the invention, a polishing pad designed to accommodate an eddy current endpoint detection system, such as the polishing pad described in the various embodiments described above, is adhered to the mounting platen 1004 by an adhesive surface. For example, in some embodiments, the polishing pad is adhesively coupled to the mounting plate 1004 using an adhesive without a carrier film (ie, transfer adhesive). In such a case, the permanent carrier film is not transferred to the mounting board with the pad, so the opening must be cut into the temporary or sacrificial release liner that is removed from the polishing pad prior to transfer to the mounting board. There is no. In one embodiment, the temporary or sacrificial release liner is removed from the polishing pad, leaving an adhesive film. Any portion of the membrane that traverses a recess in the polishing pad (such as a recess formed to accommodate an eddy current detection system) stays with the release liner or as a membrane that traverses the opening in the recess Will remain. In the latter case, that portion of the membrane may need to be removed from the recessed opening prior to mounting the polishing pad onto the mounting board. In some embodiments, neither the sacrificial release liner or the adhesive film that remains on the polishing pad is a double-sided tape.

As described above, a polishing pad for polishing a semiconductor substrate using eddy current endpoint detection has been disclosed. According to an embodiment of the present invention, a polishing pad for polishing a semiconductor substrate includes a cast homogeneous polishing body. The cast homogeneous abrasive body has a polishing surface and a back surface. The polishing pad also includes an endpoint detection region disposed within the cast homogeneous abrasive body and covalently coupled to the cast homogeneous abrasive body. The end point detection region is made of a material different from that of the cast homogeneous abrasive body, and at least a part of the end point detection region is set back with respect to the back surface of the cast homogeneous abrasive body. According to another embodiment of the invention, a polishing pad for polishing a semiconductor substrate includes a cast homogeneous abrasive body having a polishing surface and a back surface. The groove pattern is disposed within the polishing surface, and the groove pattern has a bottom depth. The polishing pad also includes an endpoint detection region formed within the cast homogeneous polishing body. The end point detection region has a first surface oriented with respect to the polishing surface and a second surface oriented with respect to the back surface. At least a portion of the first surface is flush with the bottom depth of the groove pattern and interrupts the groove pattern. The second surface is retracted into the cast homogeneous abrasive body relative to the back surface.

Claims (44)

A polishing pad for polishing a semiconductor substrate,
A cast homogeneous abrasive body having an abrasive surface and a back surface;
A groove pattern disposed in the polishing surface, the groove pattern having a bottom depth; and
An end point detection region formed in the cast homogeneous abrasive body, and
The end point detection region has a first surface oriented with respect to the polishing surface and a second surface oriented with respect to the back surface, and at least a part of the first surface is Is flush with the depth of the bottom of the groove pattern, interrupts the groove pattern, and the second surface is retracted into the cast homogenous abrasive against the back surface; Polishing pad. Entire first surface of the end point detection area is the bottom depth essentially the same plane pattern of the grooves, the polishing pad of claim 1. The first surface of the end point detection region comprises a second groove pattern having a depth substantially coplanar with the bottom depth of the groove pattern disposed in the polishing surface. Item 10. The polishing pad according to Item 1 . The individual grooves of both the groove pattern and the second groove pattern are spaced apart by a width, and the second groove pattern is offset from the groove pattern by a distance greater than the width. The polishing pad according to claim 3 . The polishing pad according to claim 1 , wherein the cast homogeneous abrasive body comprises a thermosetting closed cell polyurethane material. The polishing pad according to claim 1 , wherein the cast homogeneous polishing body including the end point detection region is opaque. A method of manufacturing a polishing pad for polishing a semiconductor substrate, comprising:
Forming a polishing pad precursor mixture in a forming mold;
Locating a lid of the forming mold in the polishing pad precursor mixture, the lid having a groove pattern disposed on the lid, the groove pattern having a break region; And
Curing the polishing pad precursor mixture to provide a cast homogeneous abrasive body having a polishing surface and a back surface, wherein the pattern of grooves from the lid is within the polishing surface Arranged, wherein the groove pattern has a bottom depth;
Providing an endpoint detection area within the cast homogeneous abrasive body,
The end point detection region has a first surface oriented with respect to the polishing surface and a second surface oriented with respect to the back surface, and at least a part of the first surface has the groove The second surface is retracted into the cast homogenous abrasive body relative to the back surface, the second surface being flush with the bottom depth of the pattern Method. The method according to claim 7 , wherein providing the end point detection region is performed by digging a part of the cast homogeneous abrasive body. The method of claim 7 , wherein providing the endpoint detection region is performed by removing a sacrificial layer embedded in the cast homogeneous abrasive. The method of claim 7 , wherein the entire first surface of the endpoint detection region is essentially flush with the bottom depth of the groove pattern. The first surface of the end point detection region has a depth that is essentially flush with the bottom depth of the groove pattern disposed within the polishing surface of the cast homogeneous abrasive body. The method of claim 7 comprising a pattern of grooves. Individual grooves of both the groove pattern and the second groove pattern are spaced apart by a width, and the second groove pattern is separated from the first groove pattern by a distance greater than the width. The method of claim 11 , wherein the method is offset. The method of claim 11 , wherein the cast homogeneous abrasive body comprises a thermoset closed cell polyurethane material. The method of claim 7 , wherein the cast homogeneous abrasive body including the endpoint detection region is opaque. A method of manufacturing a polishing pad for polishing a semiconductor substrate, comprising:
The method includes forming a polishing pad by a casting process;
The polishing pad is
A homogeneous abrasive having a polishing surface and a back surface;
A groove pattern disposed in the polishing surface, the groove pattern having a bottom depth; and
An end point detection region formed in the cast homogeneous abrasive body, and
The end point detection region has a first surface oriented with respect to the polishing surface and a second surface oriented with respect to the back surface, and at least a part of the first surface is Is flush with the depth of the bottom of the groove pattern, interrupts the groove pattern, and the second surface is retracted into the cast homogenous abrasive against the back surface; Method. The method of claim 15 , wherein the entire first surface of the endpoint detection region is essentially flush with the bottom depth of the groove pattern. The first surface of the end point detection region comprises a second groove pattern having a depth substantially coplanar with the bottom depth of the groove pattern disposed in the polishing surface. Item 16. The method according to Item 15 . The individual grooves of both the groove pattern and the second groove pattern are spaced apart by a width, and the second groove pattern is offset from the groove pattern by a distance greater than the width. The method according to claim 17 . The method of claim 15 , wherein the cast homogeneous abrasive body comprises a thermoset closed cell polyurethane material. The method of claim 15 , wherein the cast homogeneous abrasive body including the endpoint detection region is opaque. A method of manufacturing a polishing pad for polishing a semiconductor substrate, comprising:
Forming a partially cured endpoint detection region precursor in a first forming mold;
Positioning the partially cured endpoint detection area precursor on the receiving area of the lid of the second forming mold;
Providing a polishing pad precursor mixture in the second forming mold;
Moving the partially cured endpoint detection region precursor into the polishing pad precursor mixture by combining the lid and base of the second forming mold; and
By heating the polishing pad precursor mixture and the partially cured endpoint detection region precursor to provide a cast homogeneous abrasive body that is covalently bonded to the cured endpoint detection region precursor. The cast homogeneous abrasive has an abrasive surface and a back surface;
The cured end point detection region precursor is moved backward with respect to the back surface of the cast homogeneous abrasive body, and is disposed in the cast homogeneous abrasive body and shared with the cast homogeneous abrasive body. Providing a combined endpoint detection area. The method of claim 21 , wherein the retracting is performed by digging out a portion of the cured endpoint detection region precursor. The method of claim 21 , wherein the partially cured endpoint detection region precursor includes a sacrificial layer, and the retracting is performed by removing the sacrificial layer. The method according to claim 21 , wherein the end point detection region comprises a material different from that of the cast homogeneous abrasive. 25. The method of claim 24 , wherein the endpoint detection area is a locally transparent (LAT) area. The method according to claim 24 , wherein the end point detection area is an opaque area having a hardness different from that of the cast homogeneous abrasive. The method of claim 21 , wherein the entire end point detection region is retracted relative to the back surface of the cast homogeneous abrasive. The method according to claim 21 , wherein only an inner portion of the end point detection region is retracted with respect to the back surface of the cast homogeneous polishing body. The method of claim 21 , wherein the cast homogeneous abrasive body comprises a thermoset closed cell polyurethane material. The method of claim 21 , wherein the polishing surface comprises a groove pattern disposed within the polishing surface, the groove pattern being formed from a lid of the second forming mold. A method of manufacturing a polishing pad for polishing a semiconductor substrate, comprising:
Installing the support structure in the first forming mold;
Providing a detection region precursor mixture in the first forming template above the support structure;
Heating the detection region precursor mixture in the first forming mold to form a partially cured endpoint detection region precursor, the partially cured endpoint detection region precursor The body is coupled to the support structure;
By connecting the support structure to the retracted receiving area of the lid of the second forming mold, the support structure and the partial on the retracted receiving area of the lid of the second forming mold Locating the cured endpoint detection region precursor to
Providing a polishing pad precursor mixture in the second forming mold;
Moving the partially cured endpoint detection region precursor into the polishing pad precursor mixture by combining the lid and base of the second forming mold; and
By heating the polishing pad precursor mixture and the partially cured endpoint detection region precursor to provide a cast homogeneous abrasive body that is covalently bonded to the cured endpoint detection region precursor. The cast homogenous abrasive body has a polishing surface and a back surface, and the end point detection region is connected to the support structure;
Removing the support structure from the endpoint detection region. Subsequent to the heating, the cured end point detection region precursor is retracted relative to the back surface of the cast homogeneous abrasive body, thereby being disposed within the cast homogeneous abrasive body, and 32. The method of claim 31 , further comprising providing an endpoint detection region that is covalently bonded to the cast homogeneous abrasive body. 32. The method of claim 31 , wherein the support structure comprises a hard epoxy plate. 34. Providing the detection region precursor mixture in the first forming template comprises providing the detection region precursor mixture on a polymer film adhered to the support structure. Method. Concatenating said support structure receiving region said retracted in the lid, by a piece of double-sided tape, comprising adhering the support structure to the receiving area that is allowed to the recession, according to claim 34 Method. 35. The method of claim 32 , wherein the retracting is performed by digging out a portion of the cured endpoint detection region precursor. 33. The method of claim 32 , wherein the partially cured endpoint detection region precursor includes a sacrificial layer and the retreating is performed by removing the sacrificial layer. 32. The method of claim 31 , wherein the end point detection region comprises a different material than the cast homogeneous abrasive. 40. The method of claim 38 , wherein the endpoint detection area is a locally transparent (LAT) area. The method according to claim 38 , wherein the end point detection region is an opaque region having a hardness different from that of the cast homogeneous abrasive. The method according to claim 32 , wherein the entire end point detection region is retracted relative to the back surface of the cast homogeneous abrasive. The method according to claim 32 , wherein only an inner part of the end point detection region is retracted with respect to the back surface of the cast homogeneous abrasive. 32. The method of claim 31 , wherein the cast homogeneous abrasive body comprises a thermoset closed cell polyurethane material. 32. The method of claim 31 , wherein the polishing surface comprises a pattern of grooves disposed within the polishing surface, the groove pattern being formed from a lid of the second forming mold.

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