An electrochemical mechanical polishing head, polishing apparatus and polishing method

Abstract

This invention discloses an electrochemical mechanical polishing head, polishing apparatus, and polishing method, belonging to the field of wafer manufacturing technology. The electrochemical mechanical polishing head includes: a coupling disk with a central positioning hole; a carrier disk with a matching shaft portion slidably connected to the positioning hole, allowing the carrier disk to rotate with the coupling disk and / or move vertically; a conductive elastic membrane disposed below the carrier disk for loading the wafer to be processed; a retaining ring disposed below the carrier disk and located on the outer periphery of the elastic membrane; and an electrical connection assembly vertically disposed in a mounting hole along the shaft portion, one end of which is connected to a power source, and the other end connected to the central cavity of the elastic membrane, placing the wafer to be processed in an electric field formed between the elastic membrane and the polishing fluid; at least a portion of the electrical connection assembly is a flexible element that extends and retracts vertically to accommodate the deformation of the elastic membrane, thereby forming a stable electric field between the elastic membrane and the polishing fluid.

Description

[0001] This application is a divisional application of the invention patent application filed on May 12, 2025, with application number 2025106008895. Technical Field

[0002] This application relates to the field of semiconductor manufacturing technology, and in particular to an electrochemical mechanical polishing head, polishing apparatus, and polishing method. Background Technology

[0003] The integrated circuit industry is the core of the information technology industry, playing a crucial role in promoting the digital and intelligent transformation and upgrading of the manufacturing industry. Chips are the carriers of integrated circuits, and chip manufacturing involves processes such as integrated circuit design, wafer fabrication, wafer processing, electrical measurement, dicing, packaging, and testing. Among these, electrochemical mechanical polishing (ECMP) is one of the processes in wafer fabrication.

[0004] As semiconductor process nodes move into the nanometer scale (such as 5nm, below 3nm), traditional CMP faces many bottlenecks, while ECMP, due to its unique synergistic mechanism, becomes a key technology supplement.

[0005] 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, thus significantly improving the material removal rate.

[0006] Electrochemical mechanical polishing (ECMP) heads are an important component of ECMP systems, responsible for loading wafers and immersing them in the electrolyte; however, existing ECMP heads also have some problems:

[0007] 1) The gas film of an electrochemical mechanical polishing head is usually conductive from the center to the edge, which causes uneven current density between the edge and the center, which affects the uniformity of the material removal rate.

[0008] 2) The current in the gas film of the electrochemical mechanical polishing head is introduced through the wire. However, during the ECMP process, the electrochemical mechanical polishing head will perform different actions, which will cause the wire to become tangled or even broken, thus affecting the normal operation of the electrochemical mechanical polishing head. Summary of the Invention

[0009] In view of this, embodiments of this application provide an electrochemical mechanical polishing head, polishing apparatus, and polishing method to at least partially solve the above-mentioned problems.

[0010] According to a first aspect of the embodiments of this application, an electrochemical mechanical polishing head is provided, comprising:

[0011] The coupling disc has a positioning hole in the center;

[0012] The carrier disk is provided with a shaft portion, which is slidably connected in a positioning hole, so that the carrier disk rotates with the coupling disk and / or moves in the vertical direction;

[0013] A conductive elastic membrane is placed below the carrier disk to hold the wafer to be processed;

[0014] A retaining ring is positioned below the support plate and on the outer periphery of the elastic membrane;

[0015] An electrical connection assembly is vertically disposed in a mounting hole arranged along the axis, with one end connected to a power source and the other end connected to the central cavity of the elastic membrane, so that the wafer to be processed is in an electric field formed between the elastic membrane and the polishing fluid;

[0016] At least a portion of the electrical connection assembly is a flexible element that extends and retracts vertically to accommodate the deformation of the elastic membrane, thereby creating a stable electric field between the elastic membrane and the polishing fluid.

[0017] In some embodiments, the electrical connection assembly includes an upper conductive rod and a lower conductive rod, which are detachably connected by a spring-loaded pin structure to adjust the length of the electrical connection assembly; the spring-loaded pin structure includes a spring and a pin shaft, which are engaged together and abut against grooves on the opposite surfaces of the upper and lower conductive rods.

[0018] In some embodiments, a conductive disk is disposed below the lower conductive rod, the conductive disk comprising a conductive rod and a disk base integrally formed therefrom; the conductive rod is connected to the lower conductive rod, and the disk base is bonded to the elastic membrane by conductive adhesive.

[0019] In some embodiments, the elastic membrane has multiple chambers, including at least one annular chamber disposed outside the circular central chamber; the disc is bonded to the central chamber of the elastic membrane.

[0020] In some embodiments, the inner side of the central chamber is provided with a positioning groove, and the disc is bonded to the positioning groove; the bonding surface of the disc is provided with a concave-convex structure to increase the reliability of the bonding between the disc and the elastic membrane.

[0021] In some embodiments, the electrical connection assembly further includes a protective component disposed 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 component includes a first protective sleeve and a second protective sleeve, the first protective sleeve being disposed on the outside of the upper conductive rod and the second protective sleeve being disposed on the outside of the lower conductive rod.

[0022] In some embodiments, the first protective sleeve and the second protective sleeve are vertically overlapped and sleeved together, and a gap is provided between them, so that the spring pin structure adaptively adjusts the length of the electrical connection assembly.

[0023] In some embodiments, the first protective sleeve includes a flange and a sleeve, the flange being fixed to the end of the positioning hole, and the sleeve being disposed in the mounting hole of the shaft portion; a gap is provided between the lower end face of the flange and the top surface of the shaft portion.

[0024] In some embodiments, the flange is provided with a vent hole, one end of which is connected to an air source and the other end of which is connected to the mounting hole, so as to vent or evacuate the central chamber of the elastic membrane, thereby changing the load applied to the central chamber.

[0025] In some embodiments, the radial length of the central chamber is 10 to 50 mm.

[0026] In some embodiments, the central cavity of the elastic membrane is provided with a fixing hole, the conductive rod passes through the fixing hole and is connected to the lower conductive rod, and the disc base is bonded to the outside of the elastic membrane.

[0027] In some embodiments, a limiting groove is provided on the outer side of the elastic membrane, the limiting groove is concentrically arranged with the fixing hole, and the thickness of the disc base matches the depth of the limiting groove, the disc base is engaged in the limiting groove.

[0028] In some embodiments, the elastic membrane is silicone rubber or neoprene rubber, containing more than or equal to 50% silver powder.

[0029] In some embodiments, the Shore hardness of the elastic membrane is 55 to 65.

[0030] In some embodiments, the bottom surface of the elastic membrane is provided with an annular groove, and a matching annular conductive sheet is bonded to the inside of the annular groove.

[0031] In some embodiments, the annular groove is disposed at the partition rib of an adjacent chamber, and its depth is 0.2 to 0.5 mm.

[0032] In some embodiments, conductive blocks are embedded in the bottom surface of the elastic membrane. The conductive blocks are circular, rectangular, triangular, and / or elliptical in shape and are evenly distributed.

[0033] In some embodiments, the conductive block is disposed at the partition rib of an adjacent chamber.

[0034] In some embodiments, the electrochemical mechanical polishing head further includes a pressure control assembly that communicates with the central chamber and annular chamber of the elastic membrane to control the load applied to each chamber of the elastic membrane.

[0035] According to a second aspect of the embodiments of this application, an electrochemical mechanical polishing apparatus is provided, comprising:

[0036] Polishing disc, used to hold the polishing pad;

[0037] A liquid supply assembly for supplying polishing liquid toward the surface of the polishing pad;

[0038] And the electrochemical mechanical polishing head described above, used to load the wafer and abut it against the surface of the polishing pad;

[0039] A power supply is connected at one end to an electrical connection component and at the other end to a polishing slurry on the surface of a polishing pad, so that the wafer to be polished is in an electric field formed between the elastic film and the polishing slurry.

[0040] In some embodiments, the polishing pad is configured with a plurality of through holes to retain polishing fluid on the surface of the polishing pad.

[0041] In some embodiments, the positive terminal of the power supply is connected to the electrochemical mechanical polishing head, and its negative terminal is connected to the polishing liquid on the surface of the polishing pad.

[0042] According to a third aspect of the embodiments of this application, an electrochemical mechanical polishing method is provided, using the electrochemical mechanical polishing apparatus described above, wherein 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.

[0043] During wafer polishing, the pressure in the annular chamber of the elastic membrane is greater than the pressure in the central chamber.

[0044] In some embodiments, the annular chamber of the elastic membrane is under positive pressure, and the central chamber is under atmospheric pressure or negative pressure.

[0045] The beneficial effects of this invention include:

[0046] a. The provided electrochemical mechanical polishing head is internally configured with an electrical connection assembly, which is equipped with a flexible element that 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 fluid.

[0047] b. The electrical connection assembly is equipped with a detachable spring pin structure, which can dynamically adjust the extension and retraction of the spring according to the loading of the elastic diaphragm to adjust the length of the electrical connection assembly;

[0048] c. The conductive pad of the electrical connection component is bonded to the inner side of the base plate of the elastic membrane with conductive adhesive so as to transmit the current through the elastic membrane to the wafer to be polished.

[0049] d. The bottom surface of the conduction disk base is provided with a concave-convex structure, which is an annular groove, to increase the friction coefficient of the bottom surface of the disk base, thereby increasing the reliability of the adhesion between the conduction disk and the elastic membrane.

[0050] e. The central chamber of the elastic membrane is equipped with a positioning groove, the depth of which 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 wall of the positioning groove, which also helps to enhance the bonding strength between the two.

[0051] f. The electrical connection assembly also includes a protective component disposed on the outside of the upper and lower conductive rods to prevent liquid from entering the interior of the electrical connection assembly. Simultaneously, the protective component prevents other metal components from connecting to the upper and lower conductive rods and causing a short circuit that could affect the normal operation of the electrochemical mechanical polishing head;

[0052] g. The first protective sleeve of the protective component is disposed on the outside of the upper conductive rod, and the second protective sleeve is disposed on the outside of the lower conductive rod. The first protective sleeve and the second protective sleeve are vertically overlapped and sleeved together, and a gap is provided between them, so that the spring pin structure can adaptively adjust the length of the electrical connection component, thereby preventing the first protective sleeve and the second protective sleeve from interfering with each other and interfering with the free extension and contraction of the spring.

[0053] h. The conductive adhesive used to bond the conductive disk and the elastic membrane is a silicone-based conductive adhesive, which has high temperature resistance and can maintain good adhesion in the range of -50℃ to 200℃, so as to adapt to the working environment of electrochemical mechanical polishing.

[0054] i. The first protective sleeve includes a flange and a sleeve, which are integrally formed to form a tubular structure to protect the upper conductive rod 51; a gap is provided between the lower end face of the flange and the top surface of the shaft; when the bearing plate moves vertically up and down, the top surface of the shaft will not come into contact with the flange of the first protective sleeve to avoid component interference during the operation of the electrochemical polishing head.

[0055] j. The flange is equipped with a vertical vent hole, one end of which is connected to an air source and the other end is connected to a mounting hole, so as to vent or evacuate the central chamber of the elastic membrane, thereby changing the load applied to the central chamber.

[0056] That is, during electrochemical mechanical polishing, the pressure of each chamber of the elastic membrane can be controlled to adjust the polishing load applied to the wafer surface, and combined with the electrochemical reaction to comprehensively regulate the material removal rate of the wafer surface;

[0057] k. The elastic membrane is made of silicone rubber or neoprene rubber and contains more than or equal to 50% silver powder to ensure the conductivity of the elastic membrane.

[0058] l. The Shore hardness of the elastic film is 55-65, which gives the elastic film a certain degree of flexibility so that the elastic film can load the wafer by adsorption.

[0059] m. The surface of the base plate of the elastic membrane is provided with multiple annular grooves, and the surface of the base 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 with conductive adhesive in order to improve the uniformity of conductivity of the elastic membrane without affecting the flexibility of the elastic membrane itself.

[0060] n. The annular groove is set at the partition rib of the adjacent chambers of the elastic membrane, which to some extent weakens the stress concentration of the elastic membrane at the partition rib, suppresses the pressure coupling between adjacent chambers, and ensures the accuracy of the polishing pressure applied to each chamber of the elastic membrane.

[0061] o. The radial width of the annular groove is at least 2 to 3 times the wall thickness of the partition rib, and its depth is 0.2 to 0.5 mm, in order to reduce stress concentration at the partition rib;

[0062] p. Multiple conductive blocks are pre-embedded on 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, and are set at the partition ribs of adjacent chambers to weaken the stress concentration of the elastic membrane at the partition ribs, suppress the pressure coupling between adjacent chambers, and ensure the accuracy of the polishing pressure applied to each chamber of the elastic membrane. Attached Figure Description

[0063] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings.

[0064] Figure 1 This is a schematic diagram of an electrochemical mechanical polishing head provided in an embodiment of the present invention;

[0065] Figure 2 This is a schematic diagram of an electrochemical mechanical polishing apparatus provided in an embodiment of the present invention;

[0066] Figure 3 yes Figure 1 A magnified view of a section at point A in the middle;

[0067] Figure 4 This is a schematic diagram of an upper conductive rod provided in an embodiment of the present invention;

[0068] Figure 5 This is a schematic diagram of a lower conductive rod provided in an embodiment of the present invention;

[0069] Figure 6 yes Figure 1 A schematic diagram of the spring pin structure in the embodiment;

[0070] Figure 7This is a schematic diagram of an electrical connection assembly provided in an embodiment of the present invention;

[0071] Figure 8 This is a schematic diagram of a conduction disk provided in an embodiment of the present invention;

[0072] Figure 9 yes Figure 1 A partial schematic diagram of the elastic membrane in the embodiment;

[0073] Figure 10 This is a schematic diagram of a first protective sleeve provided in an embodiment of the present invention;

[0074] Figure 11 This is a bottom view of an elastic membrane provided in an embodiment of the present invention;

[0075] Figure 12 This is a bottom view of an elastic membrane provided in another embodiment of the present invention;

[0076] Figure 13 This is a schematic diagram of a conductive block disposed inside a base plate according to an embodiment of the present invention;

[0077] Figure 14 This is a schematic diagram of an electrochemical mechanical polishing head provided in another embodiment of the present invention;

[0078] Figure 15 yes Figure 14 A magnified view of a section at point B in the middle;

[0079] Figure 16 yes Figure 14 A partial schematic diagram of the central chamber of the elastic membrane in the embodiment;

[0080] Figure 17 yes Figure 14 A schematic diagram of the second protective sleeve in the embodiment. Detailed Implementation

[0081] To enable those skilled in the art to better understand the technical solutions in the embodiments of this application, the technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art should fall within the protection scope of the embodiments of this application.

[0082] The terminology used in this application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The singular forms “a,” “the,” and “the” used in this application and the appended claims are also 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 includes any or all possible combinations of one or more of the associated listed items.

[0083] 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 one another. For example, without departing from the scope of this application, first information may also be referred to as second information, and similarly, second information may also be referred to as first information. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0084] Figure 1 This is a schematic diagram of an electrochemical mechanical polishing head 100 provided in an embodiment of the present invention, which is used for polishing superhard materials such as silicon carbide. The electrochemical mechanical polishing head 100 includes:

[0085] The coupling disc 10 has 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.

[0086] The bearing plate 20 has a shaft 21 on its upper part, which is matched with the positioning hole 11 of the coupling plate 10. That is, the shape and size of the shaft 21 match the shape and size of the positioning hole 11, and the shaft 21 is slidably connected inside the positioning hole 11. At the same time, the coupling plate 10 is connected to the bearing plate 20 through the annular membrane 60, so that the bearing plate 20 can rotate with the coupling plate 10 and / or move in the vertical direction. The shaft 21 has a through mounting hole 211 inside, which extends along the length direction of the shaft 21.

[0087] A conductive elastic film 30 is disposed below the carrier disk 20 for loading the wafer to be processed;

[0088] A retaining ring 40 is positioned below the carrier disk 20 and on the outer periphery of the elastic membrane 30 to prevent the wafer to be polished from sliding out of the interior of the electrochemical mechanical polishing head 100.

[0089] Electrical connection assembly 50 is vertically disposed inside mounting hole 211;

[0090] Furthermore, one end of the electrical connection assembly 50 is connected to Figure 2 The power supply 200 shown is connected, and the other end of the electrical connection assembly 50 is connected to the central cavity of the elastic film 30, so that the wafer to be processed is in the electric field formed between the elastic film 30 and the polishing liquid.

[0091] Typically, the positive terminal of the power supply 200 is connected to the wafer via the electrical connection component 50, allowing the wafer to enter the polishing solution as the anode. When the wafer is energized, an oxidation reaction occurs, and the metal ions on its surface are ionized and dissolved to remove the material.

[0092] While electrochemical action occurs, the abrasive particles in the polishing slurry physically grind the wafer surface to remove the passivation film or softening layer generated by the electrochemical reaction, exposing a fresh surface for continuous dissolution.

[0093] To address the problems of wire pulling and tearing in existing electrochemical mechanical polishing heads, the electrical connection component 50 provided by the present invention is at least partially a flexible component that can extend and retract 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.

[0094] Figure 3 yes Figure 1 The enlarged view at point A shows that 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, so as to transmit current through the electrical connection component 50 and the conductive elastic membrane 30 to the wafer mounted below the elastic membrane 30.

[0095] Furthermore, the electrical connection assembly 50 includes an upper conductive rod 51 and a lower conductive rod 52, such as... Figure 3 As shown, a spring-loaded structure 53 is detachably connected between the two to adjust the length of the electrical connection assembly 50.

[0096] Figure 3 In this structure, the spring-loaded pin structure 53 includes a spring 531 and a pin 532, which are engaged together and abut against the grooves on the opposing surfaces of the upper conductive rod 51 and the lower conductive rod 52. The pin 532 is partially inserted into the interior of the spring 531 to provide a connecting and positioning function. Specifically, the lower diameter of the pin 532 is smaller, and it is inserted into the inner ring of the spring 531, so that the end of the spring 531 abuts against the shoulder of the pin 532.

[0097] Specifically, the bottom of the upper conductive rod 51 is equipped with Figure 4 The first groove 511 shown defines the position of the pin 532 to prevent it from tilting in the vertical direction; the top of the lower conductive rod 52 is provided with Figure 5The second groove 521 shown is used to place the spring 531. When the spring 531 is in the relaxed state, the entire spring 531 is located in the second groove 521 to ensure that the spring pin structure 53 is 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.

[0098] Figure 5 In the embodiment shown, the second groove 521 is an end-opening groove, and a limiting platform 5211 is provided on its top to serve as a locking and limiting mechanism.

[0099] To ensure the reliability of the spring pin structure 53, the pin 532 is equipped with an annular limiting protrusion 5321, such as... Figure 6 As shown, the limiting protrusion 5321 of the pin 532 is disposed 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 extension and retraction of the spring pin structure 53, that is, to determine the maximum length of the spring pin structure 53 along the axial direction, thereby preventing the spring pin structure 53 from excessively extending and retracting and affecting the normal operation of the electrochemical polishing head 100.

[0100] Figure 7 This is a schematic diagram of an electrical connection assembly 50 provided in an embodiment of the present invention. The electrical connection assembly 50 also includes a protective assembly 54, which is 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. At the same time, the protective assembly 54 can prevent other metal components from connecting with the upper conductive rod 51 and the lower conductive rod 52 and causing a short circuit, thereby ensuring the normal use of the electrochemical mechanical polishing head 100.

[0101] Furthermore, the protective component 54 includes a first protective sleeve 541 and a second protective sleeve 542, wherein the first protective sleeve 541 is disposed on the outside of the upper conductive rod 51, and the second protective sleeve 542 is disposed on the outside of the lower conductive rod 52.

[0102] 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 length of the second protective sleeve 542 is greater than the length of the lower conductive rod 52, allowing the second protective sleeve 542 to extend upwards to cover the lower conductive rod 52 and the spring pin structure 53. The first protective sleeve 541 and the second protective sleeve 542 are vertically overlapped and sleeved together, with a gap between them, allowing the spring 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 extension and contraction of the spring 531.

[0103] Furthermore, an upper conductive rod 51 is provided above it. Figure 7The conductive terminal 56 shown is connected to the positive terminal of the power supply 200, and current can be transmitted downward through the conductive terminal 56; a conductive disk 55 is disposed below the lower conductive rod 52, and the conductive disk 55 includes... Figure 8 The conductive rod 551 and the disk base 552 shown are integrally formed. The conductive rod 551 is threaded to the lower conductive rod 52, and the disk base 552 is bonded to the elastic membrane 30 with adhesive, so that the current can be conducted along the conductive terminal 56, the upper conductive rod 51, the spring pin structure 53, the lower conductive rod 52 and the conductive disk 55 to the elastic membrane 30, and finally to the wafer mounted on the elastic membrane 30.

[0104] 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 base 552 of the conduction disk 55 is bonded to the central chamber 38 of the elastic membrane 30.

[0105] In this invention, the elastic membrane 30 includes a base plate 31 and a partition rib. The partition rib extends upward from the base plate 31 to form independent chambers, so as to apply different pressures to each chamber, thereby realizing multi-zone polishing pressure control.

[0106] Specifically, the electrochemical mechanical polishing head 100 also includes a pneumatic control assembly 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 pneumatic control assembly 70 typically includes functional devices such as a proportional valve, a flow meter, a pressure sensor, and a controller. For details on the connection relationships of the various functional devices, please refer to patent CN110977750A, which will not be repeated here.

[0107] That is, during electrochemical mechanical polishing, the pressure of each chamber of the elastic membrane 30 can be controlled to adjust the polishing load applied to the wafer surface, and combined with the electrochemical reaction to comprehensively regulate the material removal rate of the wafer surface.

[0108] Figure 9 yes Figure 1 A partial schematic diagram of the elastic membrane 30 in the embodiment shows that a positioning groove 311 is provided on the inner side of the central chamber 38, that is, a positioning groove 311 is provided on the inner side of the base plate 31 of the elastic membrane 30, for bonding and fixing the disk base 552. It can be understood that the shape and size of the disk base 552 match the shape and size of the positioning groove 311, so as to accurately connect the conduction disk 55 to the center position of the elastic membrane 30, so that the current is transmitted from the center of the elastic membrane 30 outward, which helps to ensure the uniformity of the current distribution on the elastic membrane 30.

[0109] To ensure conductivity between the conductive disk 55 and the elastic film 30, a conductive adhesive is used. In some embodiments, the conductive adhesive bonding the conductive disk 55 and the elastic film 30 is a silicone-based conductive adhesive, such as Dow Corning SE 4420 conductive adhesive, which has good flexibility, is suitable for dynamic load application, and has high temperature resistance, maintaining good adhesion within a temperature range of -50℃ to 200℃ to adapt to the working environment of electrochemical mechanical polishing. Specifically, during electrochemical mechanical polishing, the wafer generates a large amount of heat, which is conducted to the elastic film 30 and the conductive disk 55. If the adhesive cannot withstand high temperatures, it will affect the reliability of the bonding between the conductive disk 55 and the elastic film 30, and may even cause an open circuit in the electrical connection component 50, thereby affecting the normal operation of the electrochemical mechanical polishing head 100.

[0110] In some embodiments, the adhesive surface of the disk base 552 is configured with an uneven structure, such as... Figure 8 As shown, this is to increase the reliability of the adhesion between the disc base and the elastic membrane. Figure 8 In this structure, the concave-convex structure is an annular groove to increase the coefficient of friction of the bottom surface of the disk base 552, thereby increasing the reliability of the adhesion between the conductive disk 55 and the elastic membrane 30.

[0111] Figure 9 In the middle, the depth of the positioning groove 311 is at least 1 / 3 of the thickness of the base plate 31 to increase the flexibility of the bottom of the central cavity 38; at the same time, adhesive can be applied to the contact area between the disc base 552 and the inner wall of the positioning groove 311, which also helps to enhance the bonding strength between the two.

[0112] In this invention, the radial length of the central chamber 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 chamber 38 of the elastic membrane 30.

[0113] Figure 10 This is a schematic diagram of a first protective sleeve 541 provided in 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 below. Figure 3 As shown, the sleeve 5412 is disposed in the mounting hole 211 of the shaft portion 21.

[0114] Furthermore, a gap 57 is provided between the lower end face of the flange 5411 and the top surface of the shaft 21. When the bearing plate 20 moves vertically up and down, the top surface of the shaft 21 will not come into contact with the flange 5411 of the first protective sleeve 541, so as to avoid component interference of the electrochemical polishing head 100 during operation.

[0115] Figure 10In the middle, the flange 5411 is provided with a vertical vent hole 5413, one end of which is connected to the air source and the other end is connected to the mounting hole 211, so as to vent or evacuate the central chamber 38 of the elastic membrane 30, thereby changing the load applied to the central chamber 38.

[0116] That is, during electrochemical mechanical polishing, the pressure in the central chamber 38 can be controlled, and the polishing load applied to the wafer surface can be adjusted, so that mechanical polishing and electrochemical reaction are combined to comprehensively regulate the material removal rate on the wafer surface.

[0117] In this invention, the elastic membrane 30 is made of silicone rubber or neoprene rubber, and contains more than or equal to 50% silver powder to ensure the conductivity of the elastic membrane 30. Specifically, during the molding of the elastic membrane 30, the silver powder needs to be uniformly incorporated into the liquid rubber, which is beneficial to the uniformity of conductivity of the elastic membrane 30.

[0118] Furthermore, the elastic film 30 has a Shore hardness of 55 to 65, which gives the elastic film 30 a certain degree of flexibility so that the elastic film 30 can load the wafer by adsorption.

[0119] Figure 11 This is a bottom view of an elastic membrane 30 provided in an embodiment of the present invention. The bottom surface of the elastic membrane 30 is provided with an annular groove 32, that is, the lower surface of the base plate 31 is provided with an annular groove 32.

[0120] Furthermore, there are multiple annular grooves 32, which are concentrically arranged on the bottom surface of the elastic membrane 30. The surface of the base plate 31 is also provided with rectangular grooves 33 to connect adjacent annular grooves 32.

[0121] Furthermore, a matching annular conductive sheet is bonded inside the annular groove 32, and a matching rectangular conductive sheet is bonded inside the rectangular groove 33, in order to further improve the uniformity of conductivity of the elastic membrane 30.

[0122] It should be noted that the annular and rectangular conductive sheets are thin metal sheets, which are bonded to the bottom surface of the elastic membrane 30 using conductive adhesive, so as to improve the uniformity of conductivity of the elastic membrane 30 without affecting the flexibility of the elastic membrane 30 itself.

[0123] In this invention, the depth of the annular groove 32 and the rectangular groove 33 is 0.2 to 1.5 mm; preferably, the depth of the annular groove 32 and the rectangular groove 33 is 0.2 to 0.5 mm.

[0124] In some embodiments, the annular groove 32 is disposed at the partition rib of the adjacent chamber of the elastic membrane 30, which to some extent weakens the stress concentration of the elastic membrane 30 at the partition rib, suppresses the pressure coupling between adjacent chambers, and ensures the accuracy of the polishing pressure applied to each chamber of the elastic membrane 30.

[0125] Specifically, the radial width of the annular groove 32 is at least 2 to 3 times the wall thickness of the partition rib, and its depth is 0.2 to 0.5 mm, in order to reduce stress concentration at the partition rib.

[0126] Figure 12 This is a bottom view of the elastic membrane 30 provided in another embodiment of the present invention. In this embodiment, a plurality of circular conductive blocks 34 are pre-embedded on the bottom surface of the elastic membrane 30. The conductive blocks 34 are metal sheets to improve the conductivity uniformity of the elastic membrane 30. That is, the bottom surface of the base plate 31 of the elastic membrane 30 is provided with grooves for bonding the conductive blocks 34, and conductive adhesive is used to bond the conductive blocks 34 to the grooves on the bottom surface of the base plate 31.

[0127] It is understandable that the conductive blocks 34 can also be rectangular, triangular and / or elliptical, and are evenly distributed.

[0128] In some embodiments, the conductive block 34 is disposed at the partition rib of adjacent chambers to weaken the stress concentration of the elastic membrane 30 at the partition rib, suppress the pressure coupling between adjacent chambers, and ensure the accuracy of the polishing pressure applied to each chamber of the elastic membrane 30.

[0129] In some embodiments, the conductive block 34 may also be disposed on the inner side of the base plate 31 of the elastic membrane 30, such as... Figure 13 As shown, the groove for placing the conductive block 34 is located inside the elastic membrane 30 to prevent particles in the polishing fluid from accumulating on the outer edge of the conductive block 34 and forming crystals. These crystals falling off can cause wafer scratches.

[0130] Figure 14 This is a schematic diagram of an electrochemical mechanical polishing head 100 provided in another embodiment of the present invention. Figure 15 yes Figure 14 A magnified view of a portion at point B in this embodiment, showing the electrochemical mechanical polishing head 100 and... Figure 1 The two are basically the same, but the following focuses on the differences between them: the connection method between the electrical connection component 50 and the elastic membrane 30.

[0131] In this embodiment, the central cavity 38 of the elastic membrane 30 is provided with Figure 16 The fixing hole 35 shown refers to the fixing hole 35 provided on the base plate 31. The transmission rod 551 of the transmission disk 55 passes through the fixing hole 35 and is threadedly connected to the lower guide rod 52. The disk seat 552 of the transmission disk 55 is bonded to the outside of the elastic membrane 30, as shown. Figure 15 As shown.

[0132] Figure 16In the embodiment shown, a limiting groove 36 is provided on the outer side of the elastic membrane 30. The limiting groove 36 is concentrically arranged with the fixing hole 35. Furthermore, the thickness of the disc base 552 matches the depth of the limiting groove 36. The disc base 552 is engaged in the limiting groove 36, so that the bottom surface of the disc base 552 is flush with the bottom surface of the bottom plate 31 of the elastic membrane 30.

[0133] To ensure the reliable connection between the conductive disk 55 and the elastic diaphragm 30, an annular protrusion 37 is provided in the central cavity 38 of the elastic diaphragm 30, extending upward from the end face of the fixing hole 35. Meanwhile, the bottom of the second protective sleeve 542 is provided with a snap-fit ​​groove 5421, such as... Figure 17 As shown, the annular protrusion 37 of the elastic membrane 30 is disposed in the snap-fit ​​groove 5421 of the second protective sleeve 542 to further ensure the reliability of the fixation between the two.

[0134] Meanwhile, the present invention provides an electrochemical mechanical polishing device 1000, the schematic diagram of which is shown below. Figure 2 As shown. The electrochemical mechanical polishing apparatus 1000 includes:

[0135] The polishing disc 300 is used to fix the polishing pad 400; specifically, the polishing pad 400 is positioned above the polishing disc 300 so that the polishing pad 400 can rotate synchronously with the polishing disc 300.

[0136] The liquid supply assembly 500 is disposed above the polishing disk 300 for supplying polishing liquid toward the surface of the polishing pad 400;

[0137] as well as Figure 2 or Figure 14 The electrochemical mechanical polishing head 100 shown is used to load a wafer and abut the wafer against the surface of the polishing pad 400;

[0138] A power supply 200 is connected at one end to the electrical connection component 50 of the electrochemical mechanical polishing head 100 and at the other end to the polishing pad 400, so that the wafer to be polished is in the electric field formed between the elastic film 30 and the polishing liquid.

[0139] In this invention, the polishing pad 400 is provided with multiple vertical through holes to retain polishing fluid on its surface. The polishing fluid is an electrolyte containing abrasive particles, such as SiO2, CeO2, and / or Al2O3, to combine electrochemical reaction with mechanical polishing, thereby increasing the material removal rate of the wafer, adapting to the polishing of materials with high hardness, and improving the polishing efficiency of the wafer.

[0140] Figure 2In the electrochemical mechanical polishing apparatus 1000 shown, the positive terminal of the power supply 200 is connected to the electrical connection component 50 of the electrochemical mechanical polishing head 100, and its negative terminal is connected to the polishing liquid on the surface of the polishing pad 400. This places the wafer to be processed in a stable electric field formed between the elastic film 30 and the polishing liquid, so that material removal can be achieved on the wafer surface under the combined action of electrochemical action and chemical mechanical polishing, thereby efficiently polishing superhard materials and improving polishing efficiency.

[0141] Furthermore, the present invention also provides an electrochemical mechanical polishing method, which uses... Figure 2 The electrochemical mechanical polishing apparatus 1000 shown in the figure performs wafer polishing. During the process, 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 the process requirements.

[0142] 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 rigid contact between the conduction disk 55 of the central chamber 38 and the wafer, ensuring that the overall material removal rate of the wafer is approximately the same in the circumferential direction.

[0143] In some embodiments, the annular chamber of the elastic membrane 30 is under positive pressure, while the central chamber 38 is under atmospheric pressure or negative pressure, so as to reasonably configure the pressure of each chamber of the elastic membrane 30, adjust the stress concentration of the conduction disk 55 and the effect of the uneven current applied by the elastic membrane 30 to the wafer on the wafer surface material removal rate, so as to obtain a wafer that meets the process requirements.

[0144] Those skilled in the art will recognize that the units and method steps of the various examples 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 implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of the embodiments of this application.

[0145] The above embodiments are only used to illustrate the embodiments of this application, and are not intended to limit the embodiments of this application. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the embodiments of this application. Therefore, all equivalent technical solutions also fall within the scope of the embodiments of this application, and the patent protection scope of the embodiments of this application should be defined by the claims.

Claims

1. An electrochemical mechanical polishing head, characterized in that, include: The coupling disc has a positioning hole in the center; The carrier plate is fitted with a shaft, which is slidably connected to the positioning hole, so that the carrier plate rotates with the coupling plate and / or moves in the vertical direction; A conductive elastic membrane is placed below the carrier disk to hold the wafer to be processed; A retaining ring is positioned below the support plate and on the outer periphery of the elastic membrane; An electrical connection assembly is vertically disposed in a mounting hole arranged along the axis. One end of the assembly 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 slurry. At least a portion of the electrical connection assembly is a flexible element that extends and retracts vertically to accommodate the deformation of the elastic membrane, thereby creating a stable electric field between the elastic membrane and the polishing fluid. The electrical connection assembly includes an upper conductive rod and a lower conductive rod, which are detachably connected by a spring-loaded structure to adjust the length of the electrical connection assembly; the spring-loaded structure includes a spring and a pin, which are engaged together and abut against the grooves on the opposite surfaces of the upper and lower conductive rods. It also includes a protective component, which is disposed 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 component includes a first protective sleeve and a second protective sleeve, the first protective sleeve being disposed on the outside of the upper conductive rod and the second protective sleeve being disposed on the outside of the lower conductive rod. The bottom of the upper conductive rod is provided with a first groove to define the position of the pin; the top of the lower conductive rod is provided with a second groove to place the spring; when the spring is in a relaxed state, it is entirely located in the second groove.

2. The electrochemical mechanical polishing head according to claim 1, characterized in that, The pin is equipped with an annular limiting protrusion, which is disposed in the second groove.

3. The electrochemical mechanical polishing head according to claim 2, characterized in that, The second groove is an end-opening groove with a limiting platform at its top; the limiting protrusion of the pin is disposed in the second groove of the lower conductive rod, and the limiting platform abuts against the top surface of the limiting protrusion to limit the upper limit of the extension and retraction of the spring pin structure.

4. The electrochemical mechanical polishing head according to claim 1, characterized in that, The lower end of the first protective sleeve is flush with the lower end of the upper conductive rod, while the length of the second protective sleeve is greater than the length of the lower conductive rod, so that the second protective sleeve extends upward to cover the lower conductive rod and the spring pin structure.

5. The electrochemical mechanical polishing head according to claim 1, characterized in that, The first protective sleeve and the second protective sleeve are vertically overlapped and sleeved together, with a gap between them, so that the spring pin structure can adaptively adjust the length of the electrical connection component, preventing the first protective sleeve and the second protective sleeve from interfering with each other and interfering with the free extension and contraction of the spring.

6. The electrochemical mechanical polishing head according to claim 1, characterized in that, A conductive terminal is disposed above the upper conductive rod, which is connected to the power supply, so that current is transmitted downward through the conductive terminal.

7. The electrochemical mechanical polishing head according to claim 6, characterized in that, A conductive disk is disposed below the lower conductive rod. The conductive disk includes a conductive rod and a disk base, which are integrally formed. The conductive rod is threaded to the lower conductive rod, and the disk base is bonded to the elastic membrane with conductive adhesive, so that the current can be conducted along the conductive terminal, the upper conductive rod, the spring pin structure, the lower conductive rod and the conductive disk to the elastic membrane, and finally conduct the current to the wafer loaded on the elastic membrane.

8. The electrochemical mechanical polishing head according to claim 7, characterized in that, The inner side of the central chamber is provided with a positioning groove, and the disc base is adhered to the positioning groove; the depth of the positioning groove is at least 1 / 3 of the thickness of the bottom plate of the elastic membrane, so as to increase the flexibility of the bottom of the central chamber.

9. The electrochemical mechanical polishing head according to claim 8, characterized in that, The conductive adhesive is applied to the contact area between the disc base and the inner wall of the positioning groove to enhance the bonding strength between the two.

10. The electrochemical mechanical polishing head according to claim 9, characterized in that, The conductive adhesive is a silicone-based conductive adhesive, suitable for the application of dynamic loads.

11. An electrochemical mechanical polishing apparatus, characterized in that, include: Polishing disc, used to hold the polishing pad; A liquid supply assembly for supplying polishing liquid toward the surface of the polishing pad; And the electrochemical mechanical polishing head according to any one of claims 1-10, for loading a wafer and abutting it against the surface of a polishing pad; A power supply is connected at one end to an electrical connection component and at the other end to a polishing slurry on the surface of a polishing pad, so that the wafer to be polished is in an electric field formed between the elastic film and the polishing slurry.

12. The electrochemical mechanical polishing apparatus according to claim 11, characterized in that, The polishing pad is provided with multiple vertical through holes to retain polishing fluid on the surface of the polishing pad.

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