Electrochemical mechanical polishing head, polishing device and polishing method

Abstract

The present invention discloses an electrochemical mechanical polishing head, a polishing device, and a polishing method, which belong to the field of wafer manufacturing technology. The electrochemical mechanical polishing head comprises: a coupling disc having a positioning hole at its center; a carrier disc having a matching shaft portion, the shaft portion being slidably connected to the positioning hole so that the carrier disc rotates with the coupling disc and / or moves vertically; a conductive elastic membrane disposed below the carrier disc for loading wafers to be processed; a retaining ring disposed below the carrier disc and located on the outer periphery of the elastic membrane; an electrical connection assembly vertically disposed in a mounting hole arranged along the shaft portion, one end of which is connected to a power source and the other end is connected to the central cavity of the elastic membrane so that the wafers to be processed are placed in an electric field formed between the elastic membrane and the polishing liquid; at least a portion of the electrical connection assembly is a flexible member that expands and contracts vertically to accommodate deformation of the elastic membrane, thereby forming a stable electric field between the elastic membrane and the polishing liquid.

Description

Technical Field

[0001] The embodiments of the present application relate to the field of semiconductor manufacturing technology, and in particular to an electrochemical mechanical polishing head, a polishing device, and a polishing method. Background Art

[0002] The integrated circuit industry is at the core of the information technology industry and plays a key role in driving the transformation and upgrading of the manufacturing industry towards digitalization and intelligentization. Chips are the carriers of integrated circuits, and chip manufacturing involves a series of processes, including integrated circuit design, wafer fabrication, wafer processing, electrical measurement, sawing, packaging, and testing. Among these processes, electrochemical mechanical polishing (ECMP) is one of the key processes in wafer fabrication.

[0003] As semiconductor process nodes enter the nanoscale (such as 5nm and below 3nm), traditional CMP faces many bottlenecks. ECMP has become a key technology supplement due to its unique synergistic mechanism.

[0004] For example, when polishing SiC with high hardness, traditional CMP is extremely inefficient, while ECMP generates a SiC oxide layer in the electrolyte and mechanically removes the softened layer, significantly improving the material removal rate.

[0005] The electrochemical mechanical polishing (ECMP) head is an important component of the ECMP system, responsible for loading the wafer and placing the wafer in the electrolyte. However, existing ECMMP heads also have some problems:

[0006] 1) The gas film of the electrochemical mechanical polishing head usually conducts electricity from the center to the edge, which causes uneven current density between the edge and the center, affecting the uniformity of the material removal rate;

[0007] 2) The current for the ECMMP head's air film is introduced through a wire. However, during the ECMP process, the ECMMP head will perform different movements, which can cause the wire to become entangled or even pulled and broken, thus affecting the normal operation of the ECMMP head. Summary of the Invention

[0008] In view of this, embodiments of the present application provide an electrochemical mechanical polishing head, a polishing device, and a polishing method to at least partially solve the above-mentioned problems.

[0009] According to a first aspect of an embodiment of the present application, there is provided an electrochemical mechanical polishing head, comprising:

[0010] A coupling plate with a positioning hole at its center;

[0011] The bearing plate is matched with a shaft portion, and the shaft portion is slidably connected to the positioning hole, so that the bearing plate rotates with the coupling plate and / or moves in the vertical direction;

[0012] A conductive elastic membrane is provided below the carrier plate and is used to load the wafers to be processed;

[0013] A retaining ring is disposed below the carrier plate and located on the outer periphery of the elastic membrane;

[0014] an electrical connection assembly vertically disposed in a mounting hole arranged along the shaft, one end of which is connected to a power source and the other end is connected to the central cavity of the elastic membrane, so that the wafer to be processed is in the electric field formed between the elastic membrane and the polishing liquid;

[0015] At least a portion of the electrical connection assembly is a flexible member, which expands and contracts vertically to adapt to the deformation of the elastic membrane, thereby forming a stable electric field between the elastic membrane and the polishing liquid.

[0016] In some embodiments, the electrical connection assembly includes an upper conductive rod and a lower conductive rod, and a spring pin structure is detachably connected between the two to adjust the length of the electrical connection assembly; the spring pin structure includes a spring and a pin shaft, which are clamped together as a whole and abut against the grooves on the opposite surfaces of the upper conductive rod and the lower conductive rod.

[0017] In some embodiments, a conductive disk is disposed below the lower conductive rod, and the conductive disk includes a conductive rod and a disk seat, which are integrally formed; the conductive rod is connected to the lower conductive rod, and the disk seat is bonded to the elastic membrane by conductive glue.

[0018] In some embodiments, the elastic membrane has multiple chambers, including at least one annular chamber disposed outside the circular central chamber; the disc seat is bonded to the central chamber of the elastic membrane.

[0019] In some embodiments, the inner side surface of the central cavity is configured with a positioning groove, and the disc seat is bonded into the positioning groove; the bonding surface of the disc seat is configured with a concave-convex structure to increase the reliability of the bonding between the disc seat and the elastic membrane.

[0020] In some embodiments, the electrical connection assembly further includes a protective assembly, which is arranged on the outside of the upper conductive rod and the lower conductive rod to prevent liquid from entering the interior of the electrical connection assembly; the protective assembly includes a first protective cover and a second protective cover, the first protective cover is arranged on the outside of the upper conductive rod, and the second protective cover is arranged on the outside of the lower conductive rod.

[0021] In some embodiments, the first protective sleeve and the second protective sleeve are vertically overlapped and sleeved, and a gap is provided between the two, so that the spring pin structure can adaptively adjust the length of the electrical connection assembly.

[0022] In some embodiments, the first protective sleeve includes a flange and a sleeve, the flange is fixed to the end of the positioning hole, and the sleeve is arranged in the mounting hole of the shaft; a gap is set between the lower end surface of the flange and the top surface of the shaft.

[0023] In some embodiments, the flange is provided with a vent hole, one end of which is connected to the air source and the other end is connected to the mounting hole, so as to ventilate or exhaust the central chamber of the elastic membrane, thereby changing the load applied to the central chamber.

[0024] In some embodiments, the radial length of the central chamber is 10-50 mm.

[0025] In some embodiments, the central cavity of the elastic membrane is configured with a fixing hole, the conductive rod passes through the fixing hole and is connected to the lower conductive rod, and the disk seat is adhered to the outer side of the elastic membrane.

[0026] In some embodiments, a limiting groove is configured on the outer side of the elastic membrane, the limiting groove is concentrically arranged with the fixing hole, and the thickness of the disk seat matches the depth of the limiting groove, and the disk seat is snapped into the limiting groove.

[0027] In some embodiments, the elastic film is made of silicone rubber or chloroprene rubber, and contains greater than or equal to 50% silver powder.

[0028] In some embodiments, the elastic film has a Shore hardness of 55-65.

[0029] In some embodiments, an annular groove is provided on the bottom surface of the elastic membrane, and the interior of the annular groove is bonded to a matching annular conductive sheet.

[0030] In some embodiments, the annular groove is provided at the dividing ribs between adjacent chambers, and its depth is 0.2-0.5 mm.

[0031] In some embodiments, conductive blocks are pre-embedded in the bottom surface of the elastic membrane. The conductive blocks are circular, rectangular, triangular and / or elliptical and are evenly distributed.

[0032] In some embodiments, the conductive blocks are disposed at separation ribs between adjacent chambers.

[0033] In some embodiments, the electrochemical mechanical polishing head further includes an air pressure control assembly in communication with the central chamber and the annular chamber of the elastic membrane to control the load applied to each chamber of the elastic membrane.

[0034] According to a second aspect of an embodiment of the present application, there is provided an electrochemical mechanical polishing device, comprising:

[0035] Polishing disc, used to fix the polishing pad;

[0036] a liquid supply assembly, configured to supply polishing liquid toward the surface of the polishing pad;

[0037] and the electrochemical mechanical polishing head described above, for loading the wafer and placing it against the surface of the polishing pad;

[0038] One end of the power supply is connected to the electrical connection component, and the other end is connected to the polishing liquid on the surface of the polishing pad, so that the wafer to be polished is in the electric field formed between the elastic film and the polishing liquid.

[0039] In some embodiments, the polishing pad is configured with a plurality of through holes to retain polishing liquid on the surface of the polishing pad.

[0040] In some embodiments, the positive electrode of the power supply is connected to the electrochemical mechanical polishing head, and the negative electrode thereof is connected to the polishing liquid on the surface of the polishing pad.

[0041] According to the third aspect of the embodiment of the present application, an electrochemical mechanical polishing method is provided, using the electrochemical mechanical polishing device described above. While the electrochemical mechanical polishing head performs an electrochemical reaction on the wafer, the elastic membrane performs multi-zone pressure control on the wafer to obtain a wafer that meets the process requirements.

[0042] During wafer polishing, the pressure in the annular chamber of the elastic membrane is greater than the pressure in the central chamber.

[0043] In some embodiments, the annular chamber of the elastic membrane is at positive pressure, and the central chamber is at atmospheric pressure or negative pressure.

[0044] The beneficial effects of the present invention include:

[0045] a provides an electrochemical mechanical polishing head, its internal configuration and electrical connection assembly, the electrical connection assembly is configured with a flexible member, which can automatically adjust its vertical length to adapt to the deformation of the elastic membrane, thereby forming a stable electric field between the elastic membrane and the polishing liquid;

[0046] b. The electrical connection assembly is provided with a detachable spring pin structure, which can dynamically adjust the expansion and contraction of the spring according to the loading of the elastic membrane to adjust the length of the electrical connection assembly;

[0047] c. The conductive pad of the electrical connection assembly is bonded to the inner side of the bottom plate of the elastic membrane by a conductive adhesive to transmit current through the elastic membrane to the wafer to be polished;

[0048] d. The bottom surface of the conductive disk seat is configured with a concave-convex structure, the concave-convex structure being an annular groove to increase the friction coefficient of the bottom surface of the disk seat, thereby increasing the reliability of the bonding between the conductive disk and the elastic film;

[0049] e. The central chamber of the elastic membrane is provided with a positioning groove whose depth is at least 1 / 3 of the thickness of the base plate to increase the flexibility of the bottom of the central chamber; at the same time, adhesive can be applied to the contact area between the disc base and the inner side wall of the positioning groove, which also helps to enhance the bonding strength between the two;

[0050] f. The electrical connection assembly also includes a protective assembly, which is positioned outside the upper and lower conductive rods to prevent liquid from entering the electrical connection assembly. Furthermore, the protective assembly prevents other metal components from connecting to the upper and lower conductive rods, causing a short circuit and potentially affecting the proper operation of the electrochemical mechanical polishing head.

[0051] g. The first protective sleeve of the protective assembly is disposed on the outer side of the upper conductive rod, and the second protective sleeve is disposed on the outer side of the lower conductive rod. The first protective sleeve and the second protective sleeve are vertically overlapped and sleeved, and a gap is provided between the two, so that the spring pin structure can adaptively adjust the length of the electrical connection assembly, thereby preventing the first protective sleeve and the second protective sleeve from interfering with each other and interfering with the free expansion and contraction of the spring;

[0052] h. The conductive adhesive used to bond the conductive pad and the elastic film is a silicone-based conductive adhesive that is resistant to high temperatures and can maintain good adhesion within the temperature range of -50°C to 200°C, adapting to the operating environment of electrochemical mechanical polishing.

[0053] i. The first protective sleeve includes a flange and a sleeve, both integrally formed to form a tubular structure to protect the upper conductive rod 51; a gap is provided between the lower end surface of the flange and the top surface of the shaft portion; when the carrier plate moves vertically up and down, the top surface of the shaft portion does not abut the flange of the first protective sleeve to avoid interference between components during operation of the electrochemical polishing head;

[0054] j. A vertical vent is provided on the flange, one end of which is connected to the air source and the other end is connected to the mounting hole, so as to ventilate or exhaust the central chamber of the elastic membrane, thereby changing the load applied to the central chamber.

[0055] That is, during electrochemical mechanical polishing, the pressure in each chamber of the elastic membrane can be controlled to adjust the polishing load applied to the wafer surface, and in combination with the electrochemical reaction, the material removal rate on the wafer surface can be comprehensively controlled;

[0056] k. The elastic film is silicone rubber or chloroprene rubber, which contains greater than or equal to 50% silver powder to ensure the conductivity of the elastic film;

[0057] l. The elastic film has a Shore hardness of 55 to 65, which makes the elastic film flexible enough to facilitate the loading of wafers by suction;

[0058] m. The surface of the bottom plate of the elastic membrane is provided with a plurality of annular grooves, and the surface of the bottom plate is also provided with rectangular grooves connecting adjacent annular grooves; the annular conductive sheet and the rectangular conductive sheet are metal sheets, which are bonded to the bottom surface of the elastic membrane using conductive adhesive to improve the uniformity of the conductive properties of the elastic membrane without affecting the flexibility of the elastic membrane itself;

[0059] n. Annular grooves are provided at the ribs separating adjacent chambers of the elastic membrane. This, to a certain extent, weakens the stress concentration of the elastic membrane at the ribs, suppresses pressure coupling between adjacent chambers, and ensures the accuracy of polishing pressure application in each chamber of the elastic membrane;

[0060] o. The radial width of the annular groove should be at least 2 to 3 times the wall thickness of the dividing rib, and its depth should be 0.2 to 0.5 mm to reduce stress concentration at the dividing rib;

[0061] p. Multiple conductive blocks are embedded in the bottom surface of the elastic membrane to improve the conductivity uniformity of the elastic membrane. The conductive blocks are circular, rectangular, triangular, and / or elliptical in shape and are located at the dividing ribs between adjacent chambers to weaken stress concentration on the elastic membrane at the dividing ribs, suppress pressure coupling between adjacent chambers, and ensure the accuracy of polishing pressure application in each chamber of the elastic membrane. BRIEF DESCRIPTION OF THE DRAWINGS

[0062] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments recorded in the embodiments of the present application. For ordinary technicians in this field, other drawings can also be obtained based on these drawings.

[0063] Figure 1 is a schematic diagram of an electrochemical mechanical polishing head provided by one embodiment of the present invention;

[0064] Figure 2 is a schematic diagram of an electrochemical mechanical polishing device provided by one embodiment of the present invention;

[0065] Figure 3 yes Figure 1 A partial enlarged view of point A in the middle;

[0066] Figure 4 is a schematic diagram of an upper conductive rod provided by an embodiment of the present invention;

[0067] Figure 5 is a schematic diagram of a lower conductive rod provided by an embodiment of the present invention;

[0068] Figure 6 yes Figure 1 A schematic diagram of the spring pin structure in the embodiment;

[0069] Figure 7 is a schematic diagram of an electrical connection assembly provided by one embodiment of the present invention;

[0070] Figure 8 is a schematic diagram of a conductive disk provided in one embodiment of the present invention;

[0071] Figure 9 yes Figure 1 A partial schematic diagram of the elastic membrane in the embodiment;

[0072] Figure 10 is a schematic diagram of a first protective cover provided by an embodiment of the present invention;

[0073] Figure 11 is a bottom view of an elastic membrane provided by one embodiment of the present invention;

[0074] Figure 12 is a bottom view of an elastic membrane provided by another embodiment of the present invention;

[0075] Figure 13 is a schematic diagram of a conductive block provided in an embodiment of the present invention and arranged inside a bottom plate;

[0076] Figure 14 is a schematic diagram of an electrochemical mechanical polishing head provided by another embodiment of the present invention;

[0077] Figure 15 yes Figure 14 A partial enlarged view of point B in the middle;

[0078] Figure 16 yes Figure 14 A partial schematic diagram of the central chamber of the elastic membrane in the embodiment;

[0079] Figure 17 yes Figure 14 Schematic diagram of the second protective sleeve in an embodiment. DETAILED DESCRIPTION

[0080] In order to enable those skilled in the art to better understand the technical solutions in the embodiments of the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the embodiments of the present application, all other embodiments obtained by ordinary technicians in this field should fall within the scope of protection of the embodiments of the present application.

[0081] The terms used in this application are for the purpose of describing specific embodiments only and are not intended to limit this application. As used in this application and the appended claims, the singular forms "a," "an," "the," and "the" are intended to include the plural forms, unless the context clearly indicates otherwise. It should also be understood that the term "and / or" as used herein refers to and encompasses any and all possible combinations of one or more of the associated listed items.

[0082] It should be understood that although the terms "first", "second", "third", etc. may be used in this application to describe various information, this information should not be limited to these terms. These terms are only used to distinguish information of the same type from each other. For example, without departing from the scope of this application, the first information may also be referred to as the second information, and similarly, the second information may also be referred to as the first information. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of this application, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0083] Figure 1 FIG1 is a schematic diagram of an electrochemical mechanical polishing head 100 provided in one embodiment of the present invention, which is used for polishing superhard materials such as silicon carbide. The electrochemical mechanical polishing head 100 includes:

[0084] The coupling disc 10 is a disc-shaped structure. A connecting flange is provided on the top of the coupling disc 10 to connect to the output shaft of the drive motor, thereby driving the coupling disc 10 and its connected components to rotate around the axis. A vertical positioning hole 11 is provided in the center of the coupling disc 10.

[0085] The carrier plate 20 has a shaft portion 21 disposed above it. The shaft portion 21 is matched with the positioning hole 11 of the coupling plate 10. That is, the shape and size of the shaft portion 21 match the shape and size of the positioning hole 11, and the shaft portion 21 is slidably connected to the interior of the positioning hole 11. At the same time, the coupling plate 10 is connected to the carrier plate 20 via the annular membrane 60, so that the carrier plate 20 can rotate and / or move vertically with the coupling plate 10. A through mounting hole 211 is provided inside the shaft portion 21, which extends along the length direction of the shaft portion 21.

[0086] A conductive elastic membrane 30 is disposed below the carrier plate 20 and is used to load wafers to be processed;

[0087] A retaining ring 40 is disposed below the carrier plate 20 and on the outer periphery of the elastic membrane 30 to prevent the wafer to be polished from slipping out of the interior of the electrochemical mechanical polishing head 100;

[0088] The electrical connection assembly 50 is vertically disposed inside the mounting hole 211;

[0089] Furthermore, one end of the electrical connection assembly 50 is connected to Figure 2 The power supply 200 is shown connected, and the other end of the electrical connection assembly 50 is connected to the central cavity of the elastic membrane 30, so that the wafer to be processed is in the electric field formed between the elastic membrane 30 and the polishing liquid.

[0090] Typically, the positive electrode of the power supply 200 is connected to the wafer through the electrical connection component 50, so that the wafer acts as an anode and enters the polishing liquid; after the wafer is powered on, an oxidation reaction occurs, and the metal ions on its surface are ionized and dissolved to achieve material removal.

[0091] Simultaneously with the electrochemical action, the abrasive particles in the polishing liquid physically grind the wafer surface to remove the passivation film or softened layer generated by the electrochemical reaction, exposing a fresh surface for continued dissolution.

[0092] In order to solve the problems of wire pulling and tearing in existing electrochemical mechanical polishing heads, at least a portion of the electrical connection component 50 provided by the present invention is a flexible part, which can expand and contract vertically to adapt to the deformation of the elastic membrane 30, thereby forming a stable electric field between the elastic membrane 30 and the polishing liquid to ensure the reliable operation of the electrochemical mechanical polishing head 100.

[0093] Figure 3 yes Figure 1 In the partially enlarged view at point A, the electrical connection component 50 is disposed in the mounting hole 211 of the shaft portion 21, the bottom of the electrical connection component 50 is connected to the elastic membrane 30, and the top of the electrical connection component 50 is connected to the power supply 200 to transmit current through the electrical connection component 50 and the conductive elastic membrane 30 to the wafer loaded below the elastic membrane 30.

[0094] Furthermore, the electrical connection assembly 50 includes an upper conductive rod 51 and a lower conductive rod 52. Figure 3 As shown, a spring pin structure 53 is detachably connected between the two to adjust the length of the electrical connection assembly 50.

[0095] Figure 3 In the figure, the spring-pin structure 53 comprises a spring 531 and a pin 532, which are integrally engaged and abut against grooves on the opposing surfaces of the upper conductive rod 51 and the lower conductive rod 52. The pin 532 partially inserts into the interior of the spring 531, providing a connection and positioning function. Specifically, the lower portion of the pin 532 has a smaller diameter and inserts into the inner ring of the spring 531, allowing the end of the spring 531 to abut against the shoulder of the pin 532.

[0096] Specifically, the bottom of the upper conductive rod 51 is configured with Figure 4 The first groove 511 is shown to limit the position of the pin 532 to prevent it from deflecting in the vertical direction; the top of the lower conductive rod 52 is configured with Figure 5The second groove 521 is shown for receiving a spring 531. When the spring 531 is in a relaxed state, the entire spring 531 is located in the second groove 521, ensuring that the spring pin structure 53 remains in the second groove 521 in both the extended and compressed states. This prevents the spring 531 from extending out of the second groove 521 and causing the spring pin structure 53 to deflect.

[0097] Figure 5 In the illustrated embodiment, the second groove 521 is an open-ended groove, and a limiting platform 5211 is disposed on the top thereof to play a role of clamping and limiting.

[0098] In order to ensure the reliability of the fixing of the elastic pin structure 53, the pin shaft 532 is provided with an annular limiting protrusion 5321, such as Figure 6 As shown, the limiting protrusion 5321 of the pin shaft 532 is set in the second groove 521 of the lower conductive rod 52, and the limiting platform 5211 abuts against the top surface of the limiting protrusion 5321 to limit the upper limit of the expansion and contraction of the elastic pin structure 53, that is, to determine the maximum length of the elastic pin structure 53 along the axial direction, thereby preventing the elastic pin structure 53 from excessive expansion and contraction and affecting the normal operation of the electrochemical polishing head 100.

[0099] Figure 7 FIG2 is a schematic diagram of an electrical connection assembly 50 according to an embodiment of the present invention. The electrical connection assembly 50 further includes a protective assembly 54 disposed outside the upper conductive rod 51 and the lower conductive rod 52 to prevent liquid from entering the interior of the electrical connection assembly 50. Furthermore, the protective assembly 54 prevents other metal components from connecting with the upper conductive rod 51 and the lower conductive rod 52 and causing a short circuit, thereby ensuring normal operation of the electrochemical mechanical polishing head 100.

[0100] Furthermore, the protective assembly 54 includes a first protective sleeve 541 and a second protective sleeve 542 , wherein the first protective sleeve 541 is arranged on the outside of the upper conductive rod 51 , and the second protective sleeve 542 is arranged on the outside of the lower conductive rod 52 .

[0101] Figure 7 In the illustrated embodiment, the lower end of the first protective sleeve 541 is substantially flush with the lower end of the upper conductive rod 51, while the second protective sleeve 542 is longer than the lower conductive rod 52, allowing the second protective sleeve 542 to extend upward to cover the lower conductive rod 52 and the elastic pin structure 53. The first protective sleeve 541 and the second protective sleeve 542 vertically overlap and are connected, with a gap provided between them, allowing the elastic pin structure 53 to adaptively adjust the length of the electrical connection assembly 50, thereby preventing the first protective sleeve 541 and the second protective sleeve 542 from interfering with each other and interfering with the free expansion and contraction of the spring 531.

[0102] Furthermore, there is a conductive rod 51 disposed above the conductive rod 51. Figure 7The conductive terminal 56 shown is connected to the positive electrode of the power source 200, and the current can be transmitted downward through the conductive terminal 56; a conductive plate 55 is configured below the lower conductive rod 52, and the conductive plate 55 includes Figure 8 The conductive rod 551 and disk base 552 are integrally formed. The conductive rod 551 is threadedly connected to the lower conductive rod 52, and the disk base 552 is glued to the elastic membrane 30. This allows current to flow through the conductive terminals 56, upper conductive rod 51, spring structure 53, lower conductive rod 52, and conductive disk 55 to the elastic membrane 30, ultimately transferring the current to the wafer mounted on the elastic membrane 30.

[0103] Figure 1 In the illustrated embodiment, the elastic membrane 30 has multiple chambers. Specifically, the elastic membrane 30 includes a circular central chamber 38 located at the center of the elastic membrane 30 ; the elastic membrane 30 also includes at least one annular chamber located outside the central chamber 38 ; wherein the disc seat 552 of the conductive disc 55 is bonded to the central chamber 38 of the elastic membrane 30 .

[0104] In the present invention, the elastic membrane 30 includes a bottom plate 31 and separation ribs, which extend upward from the bottom plate 31 to form independent chambers, so as to apply different pressures to each chamber, thereby achieving multi-zone polishing pressure control.

[0105] Specifically, the electrochemical mechanical polishing head 100 further includes an air pressure control component 70, such as Figure 2 As shown, it communicates with the central chamber 38 and the annular chamber of the elastic membrane 30 to control the polishing load applied to each chamber of the elastic membrane 30. The air pressure control assembly 70 typically includes functional components such as a proportional valve, a flow meter, a pressure sensor, and a controller. The connection relationship between these functional components is detailed in patent CN110977750A and will not be repeated here.

[0106] That is, during electrochemical mechanical polishing, the pressure in each chamber of the elastic membrane 30 can be controlled to adjust the polishing load applied to the wafer surface, so as to combine with the electrochemical reaction to comprehensively regulate the material removal rate on the wafer surface.

[0107] Figure 9 yes Figure 1 A partial schematic diagram of the elastic membrane 30 in this embodiment shows a positioning groove 311 disposed on the inner side of the central cavity 38, specifically, on the inner side of the base plate 31 of the elastic membrane 30. This groove is used for adhesively securing the disc seat 552. It will be appreciated that the shape and dimensions of the disc seat 552 match those of the positioning groove 311, precisely attaching the conductive disc 55 to the center of the elastic membrane 30. This allows current to be transferred outward from the center of the elastic membrane 30, which helps ensure uniform current distribution across the elastic membrane 30.

[0108] To ensure electrical conductivity between the conductive plate 55 and the elastic membrane 30, a conductive adhesive is used as the bonding adhesive. In some embodiments, the conductive adhesive used to bond the conductive plate 55 and the elastic membrane 30 is a silicone-based conductive adhesive, such as Dow Corning SE 4420 conductive adhesive. This adhesive exhibits excellent flexibility and is suitable for dynamic load application. Furthermore, this conductive adhesive is heat-resistant and can maintain good adhesion within a temperature range of -50°C to 200°C, adapting to the operating environment of electrochemical mechanical polishing. Specifically, during electrochemical mechanical polishing, the wafer generates a large amount of heat, which is transferred to the elastic membrane 30 and the conductive plate 55. If the adhesive is not heat-resistant, the reliability of the bonding between the conductive plate 55 and the elastic membrane 30 may be affected, and the electrical connection assembly 50 may even be disconnected, thereby affecting the normal operation of the electrochemical mechanical polishing head 100.

[0109] In some embodiments, the bonding surface of the disc base 552 is configured with a concave-convex structure, such as Figure 8 As shown, the reliability of the bonding between the disc seat and the elastic membrane is increased. Figure 8 In the embodiment, the concave-convex structure is an annular groove to increase the friction coefficient of the bottom surface of the disc seat 552, thereby increasing the reliability of the bonding between the conductive disc 55 and the elastic membrane 30.

[0110] Figure 9 In the embodiment, the depth of the positioning groove 311 is at least 1 / 3 of the thickness of the bottom plate 31 to increase the flexibility of the bottom of the central cavity 38; at the same time, the adhesive can be applied to the contact point between the disc seat 552 and the inner wall of the positioning groove 311, which is also conducive to enhancing the bonding strength between the two.

[0111] In the present invention, the radial length of the central cavity 38 is 10-50 mm, and the radial dimension of the positioning groove 311 is 5-30 mm, so as to ensure the flexibility of the central cavity 38 of the elastic membrane 30 .

[0112] Figure 10 Schematic diagram of the first protective sleeve 541 provided by an embodiment of the present invention, the first protective sleeve 541 includes a flange 5411 and a sleeve 5412, which are integrally formed to form a tubular structure, thereby protecting the upper conductive rod 51. The flange 5411 is fixed to the end of the positioning hole 11, as shown in FIG. Figure 3 As shown, the sleeve 5412 is disposed in the mounting hole 211 of the shaft portion 21 .

[0113] Furthermore, a gap 57 is provided between the lower end surface of the flange 5411 and the top surface of the shaft 21. When the carrier plate 20 moves vertically up and down, the top surface of the shaft 21 does not abut against the flange 5411 of the first protective sleeve 541, thereby preventing component interference during operation of the electrochemical polishing head 100.

[0114] Figure 10In the figure, a vertical vent hole 5413 is provided on the flange 5411 , one end of which is connected to the air source and the other end is connected to the mounting hole 211 , so as to ventilate or exhaust the central chamber 38 of the elastic membrane 30 , thereby changing the load applied to the central chamber 38 .

[0115] That is, during electrochemical mechanical polishing, the pressure of the central chamber 38 can be controlled to adjust the polishing load applied to the wafer surface, so that mechanical polishing is combined with electrochemical reaction to comprehensively regulate the material removal rate on the wafer surface.

[0116] In the present invention, the elastic membrane 30 is made of silicone rubber or chloroprene rubber and contains greater than or equal to 50% silver powder to ensure the conductivity of the elastic membrane 30. Specifically, during molding of the elastic membrane 30, the silver powder needs to be evenly blended into the liquid rubber, which promotes uniform conductivity of the elastic membrane 30.

[0117] Furthermore, the Shore hardness of the elastic membrane 30 is 55-65, so that the elastic membrane 30 has a certain flexibility, so that the elastic membrane 30 can load the wafer by suction.

[0118] Figure 11 3 is a bottom view of an elastic membrane 30 provided in one embodiment of the present invention. An annular groove 32 is provided on the bottom surface of the elastic membrane 30 , that is, an annular groove 32 is provided on the lower surface of the bottom plate 31 .

[0119] Furthermore, there are a plurality of annular grooves 32 , which are concentrically disposed on the bottom surface of the elastic membrane 30 . A rectangular groove 33 is further disposed on the surface of the bottom plate 31 to connect adjacent annular grooves 32 .

[0120] Furthermore, a matching annular conductive sheet is bonded to the inside of the annular groove 32 , and a matching rectangular conductive sheet is bonded to the inside of the rectangular groove 33 , so as to further improve the uniformity of the electrical conductivity of the elastic membrane 30 .

[0121] It should be noted that the annular conductive sheet and the rectangular conductive sheet are metal sheets, which are bonded to the bottom surface of the elastic membrane 30 using conductive adhesive to improve the uniformity of the electrical conductivity of the elastic membrane 30 without affecting the flexibility of the elastic membrane 30 itself.

[0122] In the present invention, the depth of the annular groove 32 and the rectangular groove 33 is 0.2-1.5 mm; preferably, the depth of the annular groove 32 and the rectangular groove 33 is 0.2-0.5 mm.

[0123] In some embodiments, the annular groove 32 is arranged at the dividing ribs of adjacent chambers of the elastic membrane 30, which weakens the stress concentration of the elastic membrane 30 at the dividing ribs to a certain extent, suppresses the pressure coupling between adjacent chambers, and ensures the accuracy of the polishing pressure applied to each chamber of the elastic membrane 30.

[0124] Specifically, the radial width of the annular groove 32 is at least 2 to 3 times the wall thickness of the separation rib, and the depth thereof is 0.2 to 0.5 mm, so as to weaken the stress concentration at the separation rib.

[0125] Figure 12 This is a bottom view of an elastic membrane 30 according to another embodiment of the present invention. In this embodiment, the bottom surface of the elastic membrane 30 is pre-embedded with multiple circular conductive blocks 34. The conductive blocks 34 are metal sheets to improve the uniformity of the conductivity of the elastic membrane 30. Specifically, the bottom surface of the base plate 31 of the elastic membrane 30 is provided with grooves for bonding the conductive blocks 34. The conductive blocks 34 are bonded to the grooves on the bottom surface of the base plate 31 using conductive adhesive.

[0126] It is understandable that the conductive blocks 34 may also be rectangular, triangular and / or elliptical, and may be evenly distributed.

[0127] In some embodiments, the conductive blocks 34 are disposed at the dividing ribs of adjacent chambers to weaken the stress concentration of the elastic membrane 30 at the dividing ribs, suppress the pressure coupling between adjacent chambers, and ensure the accuracy of the polishing pressure applied to each chamber of the elastic membrane 30.

[0128] In some embodiments, the conductive block 34 may also be disposed on the inner side of the bottom plate 31 of the elastic membrane 30, such as Figure 13 As shown, the groove for placing the conductive block 34 is set on the inner side of the elastic membrane 30 to prevent particles in the polishing liquid from accumulating on the outer edge of the conductive block 34 and forming crystals. These crystals fall off and cause scratches on the wafer.

[0129] Figure 14 is a schematic diagram of an electrochemical mechanical polishing head 100 provided in another embodiment of the present invention. Figure 15 yes Figure 14 The partial enlarged view of B in the figure shows the electrochemical mechanical polishing head 100 in this embodiment and Figure 1 The diagrams are basically the same, and the following focuses on the difference between the two: the connection method between the electrical connection component 50 and the elastic membrane 30.

[0130] In this embodiment, the central chamber 38 of the elastic membrane 30 is provided with Figure 16 The fixing hole 35 shown is provided on the bottom plate 31. The conducting rod 551 of the conducting plate 55 passes through the fixing hole 35 and is threadedly connected to the lower guide rod 52. The disc seat 552 of the conducting plate 55 is bonded to the outer side of the elastic membrane 30. Figure 15 shown.

[0131] Figure 16In the embodiment shown, a limiting groove 36 is configured on the outer side of the elastic membrane 30, and the limiting groove 36 is arranged concentrically with the fixing hole 35. In addition, the thickness of the disc seat 552 matches the depth of the limiting groove 36. The disc seat 552 is snapped into the limiting groove 36 so that the bottom surface of the disc seat 552 is flush with the bottom surface of the bottom plate 31 of the elastic membrane 30.

[0132] In order to ensure the reliability of the connection between the conductive plate 55 and the elastic membrane 30, an annular protrusion 37 is provided in the central cavity 38 of the elastic membrane 30, which extends upward from the end surface of the fixing hole 35. At the same time, the bottom of the second protective sleeve 542 is provided with a snap-fit groove 5421. Figure 17 As shown, the annular protrusion 37 of the elastic membrane 30 is disposed in the engaging groove 5421 of the second protective sleeve 542 to further ensure the reliability of the fixation between the two.

[0133] At the same time, the present invention provides an electrochemical mechanical polishing device 1000, the schematic diagram of which is as follows: Figure 2 As shown. The electrochemical mechanical polishing device 1000 includes:

[0134] The polishing plate 300 is used to fix the polishing pad 400 ; specifically, the polishing pad 400 is disposed above the polishing plate 300 , so that the polishing pad 400 can rotate synchronously with the polishing plate 300 .

[0135] a liquid supply assembly 500 , which is disposed above the polishing plate 300 and is used to supply polishing liquid toward the surface of the polishing pad 400 ;

[0136] as well as Figure 2 or Figure 14 The electrochemical mechanical polishing head 100 is shown for loading a wafer and placing the wafer against the surface of a polishing pad 400 ;

[0137] One end of the power supply 200 is connected to the electrical connection assembly 50 of the electrochemical mechanical polishing head 100 , and the other end is connected to the polishing pad 400 , so that the wafer to be polished is in the electric field formed between the elastic membrane 30 and the polishing liquid.

[0138] In the present invention, the polishing pad 400 is configured with multiple vertical through-holes to retain polishing liquid on the surface of the polishing pad 400. The polishing liquid is an electrolyte containing abrasive particles, wherein the abrasive particles contained are SiO2, CeO2 and / or Al2O3, etc., so as to combine electrochemical reaction with mechanical polishing to increase the material removal rate of the wafer, adapt to the polishing of materials with higher hardness, and improve the polishing efficiency of the wafer.

[0139] Figure 2In the electrochemical mechanical polishing device 1000 shown, the positive electrode of the power supply 200 is connected to the electrical connection component 50 of the electrochemical mechanical polishing head 100, and the negative electrode thereof is connected to the polishing liquid on the surface of the polishing pad 400, so that the wafer to be processed is placed in a stable electric field formed between the elastic membrane 30 and the polishing liquid, so that material removal from the wafer surface can be achieved under the combined action of electrochemical action and chemical mechanical polishing, so as to efficiently polish superhard materials and improve polishing efficiency.

[0140] In addition, the present invention also provides an electrochemical mechanical polishing method, which uses Figure 2 In the electrochemical mechanical polishing device 1000 shown, when polishing a wafer, the electrochemical mechanical polishing head 100 performs an electrochemical reaction on the wafer while the elastic membrane 30 performs multi-zone pressure control on the wafer to obtain a wafer that meets process requirements.

[0141] During wafer polishing, the pressure in the annular chamber of the elastic membrane 30 is greater than the pressure in the central chamber 38 to balance the hard contact between the conductive disk 55 in the central chamber 38 and the wafer, ensuring that the comprehensive material removal rate of the wafer in the circumferential direction is roughly the same.

[0142] In some embodiments, the annular chamber of the elastic membrane 30 is at positive pressure, while the central chamber 38 is at atmospheric pressure or negative pressure, so as to rationally configure the pressure of each chamber of the elastic membrane 30, adjust the stress concentration of the conductive disk 55 and the influence of the uneven current applied to the wafer by the elastic membrane 30 on the material removal rate of the wafer surface, and obtain a wafer that meets the process requirements.

[0143] Those skilled in the art will appreciate that the units and method steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of the embodiments of this application.

[0144] The above implementation methods are only used to illustrate the embodiments of the present application, and are not intended to limit the embodiments of the present application. Ordinary technicians in the relevant technical field can make various changes and modifications without departing from the spirit and scope of the embodiments of the present application. Therefore, all equivalent technical solutions also fall within the scope of the embodiments of the present application, and the scope of patent protection of the embodiments of the present application should be defined by the claims.

Claims

1. An electrochemical mechanical polishing head, characterized in that: include: A coupling plate with a positioning hole at its center; The bearing plate is matched with a shaft portion, and the shaft portion is slidably connected to the positioning hole, so that the bearing plate rotates with the coupling plate and / or moves in the vertical direction; A conductive elastic membrane is provided below the carrier plate and is used to load the wafers to be processed; A retaining ring is disposed below the carrier plate and located on the outer periphery of the elastic membrane; an electrical connection assembly vertically disposed in a mounting hole arranged along the shaft, one end of which is connected to a power source and the other end is connected to the central cavity of the elastic membrane, so that the wafer to be processed is in the electric field formed between the elastic membrane and the polishing liquid; At least a portion of the electrical connection assembly is a flexible member that expands and contracts vertically to accommodate deformation of the elastic membrane, thereby forming a stable electric field between the elastic membrane and the polishing liquid. The electrical connection assembly includes an upper conductive rod and a lower conductive rod, with a spring pin structure detachably connected therebetween to adjust the length of the electrical connection assembly. The spring pin structure includes a spring and a pin shaft, which are integrally engaged with each other and abut against grooves on opposing surfaces of the upper and lower conductive rods. It also includes a protective component, which is arranged on the outside of the upper conductive rod and the lower conductive rod to prevent liquid from entering the interior of the electrical connection component; the protective component includes a first protective cover and a second protective cover, the first protective cover is arranged on the outside of the upper conductive rod, and the second protective cover is arranged on the outside of the lower conductive rod.

2. The electrochemical mechanical polishing head according to claim 1, characterized in that: A conductive disk is disposed below the lower conductive rod. The conductive disk includes a conductive rod and a disk seat, which are integrally formed. The conductive rod is connected to the lower conductive rod, and the disk seat is bonded to the elastic membrane through conductive adhesive.

3. The electrochemical mechanical polishing head according to claim 2, characterized in that: The elastic membrane has multiple chambers, including at least one annular chamber arranged outside the circular central chamber; the disc seat is bonded to the central chamber of the elastic membrane.

4. The electrochemical mechanical polishing head according to claim 3, characterized in that: The inner side surface of the central cavity is provided with a positioning groove, and the disc seat is bonded in the positioning groove; the bonding surface of the disc seat is provided with a concave-convex structure to increase the reliability of bonding between the disc seat and the elastic membrane.

5. The electrochemical mechanical polishing head according to claim 1, wherein: The first protective sleeve and the second protective sleeve are vertically overlapped and sleeved, and a gap is provided between the two, so that the elastic pin structure can adaptively adjust the length of the electrical connection component.

6. The electrochemical mechanical polishing head according to claim 1, characterized in that: The first protective sleeve includes a flange and a sleeve, the flange is fixed to the end of the positioning hole, and the sleeve is arranged in the mounting hole of the shaft; a gap is set between the lower end surface of the flange and the top surface of the shaft.

7. The electrochemical mechanical polishing head according to claim 6, characterized in that: The flange is provided with a vent hole, one end of which is connected to the air source and the other end is connected to the mounting hole, so as to ventilate or exhaust the central cavity of the elastic membrane, thereby changing the load applied to the central cavity.

8. The electrochemical mechanical polishing head according to claim 7, characterized in that: The radial length of the central cavity is 10-50 mm.

9. The electrochemical mechanical polishing head according to claim 3, characterized in that: The central cavity of the elastic membrane is provided with a fixing hole, the conductive rod passes through the fixing hole and is connected with the lower conductive rod, and the disc seat is adhered to the outer side of the elastic membrane.

10. The electrochemical mechanical polishing head according to claim 9, characterized in that: A limiting groove is configured on the outer side of the elastic membrane. The limiting groove is concentrically arranged with the fixing hole. In addition, the thickness of the disc seat matches the depth of the limiting groove, and the disc seat is snap-connected to the limiting groove.

11. The electrochemical mechanical polishing head according to claim 1, characterized in that: The elastic film is made of silicone rubber or chloroprene rubber, and contains greater than or equal to 50% of silver powder.

12. The electrochemical mechanical polishing head according to claim 1, wherein: The Shore hardness of the elastic film is 55-65.

13. The electrochemical mechanical polishing head according to claim 1, wherein: The bottom surface of the elastic membrane is provided with an annular groove, and the interior of the annular groove is bonded to a matching annular conductive sheet.

14. The electrochemical mechanical polishing head according to claim 13, wherein: The annular groove is arranged at the dividing ribs of adjacent chambers, and its depth is 0.2-0.5 mm.

15. The electrochemical mechanical polishing head according to claim 1, wherein: Conductive blocks are pre-buried on the bottom surface of the elastic membrane. The conductive blocks are circular, rectangular, triangular and / or elliptical and are evenly distributed.

16. The electrochemical mechanical polishing head according to claim 15, characterized in that: The conductive blocks are arranged at the separation ribs of adjacent chambers.

17. The electrochemical mechanical polishing head according to claim 3, wherein: The invention also includes an air pressure control component which is in communication with the central chamber and the annular chamber of the elastic membrane so as to control the load applied by each chamber of the elastic membrane.

18. An electrochemical mechanical polishing device, characterized in that: include: Polishing disc, used to fix the polishing pad; a liquid supply assembly, configured to supply polishing liquid toward the surface of the polishing pad; and an electrochemical mechanical polishing head according to any one of claims 1 to 17, for loading a wafer and bringing it into contact with the surface of a polishing pad; One end of the power supply is connected to the electrical connection component, and the other end is connected to the polishing liquid on the surface of the polishing pad, so that the wafer to be polished is in the electric field formed between the elastic film and the polishing liquid.

19. The electrochemical mechanical polishing device according to claim 18, characterized in that: The polishing pad is provided with a plurality of through holes for retaining polishing liquid on the surface of the polishing pad.

20. The electrochemical mechanical polishing device according to claim 18, wherein The positive electrode of the power supply is connected to the electrochemical mechanical polishing head, and the negative electrode thereof is connected to the polishing liquid on the surface of the polishing pad.

21. An electrochemical mechanical polishing method, characterized in that: When the electrochemical mechanical polishing device according to claim 18 is used, the electrochemical mechanical polishing head performs an electrochemical reaction on the wafer while the elastic membrane performs multi-zone pressure control on the wafer to obtain a wafer that meets the process requirements.

22. The electrochemical mechanical polishing method according to claim 21, characterized in that: During wafer polishing, the pressure in the annular chamber of the elastic membrane is greater than the pressure in the central chamber.

23. The electrochemical mechanical polishing method according to claim 22, characterized in that: The annular chamber of the elastic membrane is at positive pressure, and the central chamber is at atmospheric pressure or negative pressure.

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