Electrochemical mechanical polishing head, polishing device and polishing method

Abstract

The invention discloses an electrochemical mechanical polishing head, a polishing device and a polishing method, and belongs to the technical field of wafer manufacturing. The electrochemical mechanical polishing head comprises a coupling disc and a polishing head, wherein a positioning hole is formed in the center of the coupling disc; the bearing disc is provided with a shaft part in a matched mode, and the shaft part is connected into the positioning hole in a sliding mode, so that the bearing disc rotates along with the coupling disc and / or moves in the vertical direction; the conductive elastic film is arranged below the bearing disc and is used for loading a wafer to be processed; the retaining ring is arranged below the bearing disc and is positioned on the peripheral side of the elastic film; the electric connection assembly is vertically arranged in a mounting hole configured along the shaft part, one end of the electric connection assembly is connected with a power supply, and the other end of the electric connection assembly is connected with a central cavity of the elastic film, so that a wafer to be processed is located in an electric field formed between the elastic film and the polishing solution; at least part of the electric connection assembly is a flexible part and stretches out and draws back in the vertical direction to adapt to deformation of the elastic film, and then a stable electric field is formed between the elastic film and the polishing solution.

Description

Technical Field

[0001] 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 the core of the information technology industry and plays a key role in boosting the transformation and upgrading of the manufacturing industry to digitalization and intelligentization. A chip is the carrier of an integrated circuit, and chip manufacturing involves process flows such as integrated circuit design, wafer manufacturing, wafer processing, electrical measurement, cutting and packaging, and testing. Among them, Electrochemical Mechanical Polishing (ECMP) is one of the manufacturing processes in wafer manufacturing.

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

[0004] For example, when polishing SiC with high hardness, the efficiency of traditional CMP is extremely low, while ECMP generates a SiC oxide layer in the electrolyte and mechanically removes the softened layer, resulting in a significant increase in the material removal rate.

[0005] The electrochemical mechanical polishing head is an important part of the ECMP system, which is responsible for loading the wafer and immersing the wafer in the electrolyte; however, there are also some problems with the existing electrochemical mechanical polishing heads: 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; 2) The current of the gas film of the electrochemical mechanical polishing head is introduced through a wire, but during the ECMP process, the electrochemical mechanical polishing head will perform different actions, which may cause the wire to wind and even be pulled and broken, thereby affecting the normal operation of the electrochemical mechanical polishing head. Summary of the Invention

[0006] 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 problems.

[0007] According to a first aspect of the embodiments of the present application, an electrochemical mechanical polishing head is provided, which includes: A coupling disk with a positioning hole provided at the center; A carrier disk with a shaft portion correspondingly provided, the shaft portion being slidably connected in the positioning hole so that the carrier disk rotates and / or moves in the vertical direction along with the coupling disk; A conductive elastic film provided below the carrier disk for loading the wafer to be processed; Retention ring, disposed below the carrier plate and on the outer peripheral side of the elastic membrane; Electric connection component, vertically disposed in the mounting hole configured along the shaft portion, one end thereof is connected to the power supply, and the other end is connected to the central chamber 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 part of the electric connection component 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.

[0008] In some embodiments, the electric connection component 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 electric connection component; the spring pin structure includes a spring and a pin shaft, which are clamped together and abutted in the grooves on the opposite surfaces of the upper conductive rod and the lower conductive rod.

[0009] In some embodiments, a conduction plate is disposed below the lower conductive rod, and the conduction plate includes a conduction rod and a plate seat, which are integrally formed; the conduction rod is connected to the lower conductive rod, and the plate seat is bonded to the elastic membrane through a conductive adhesive.

[0010] In some embodiments, there are multiple chambers in the elastic membrane, and it further includes at least one annular chamber and is disposed outside the circular central chamber; the plate seat is bonded to the central chamber of the elastic membrane.

[0011] In some embodiments, a positioning groove is configured on the inner side surface of the central chamber, and the plate seat is bonded in the positioning groove; the bonding surface of the plate seat is configured with an uneven structure to increase the bonding reliability between the plate seat and the elastic membrane.

[0012] In some embodiments, the electric connection component further includes a protection component, which is disposed outside the upper conductive rod and the lower conductive rod to prevent liquid from entering the inside of the electric connection component; the protection component includes a first protection sleeve and a second protection sleeve, the first protection sleeve is disposed outside the upper conductive rod, and the second protection sleeve is disposed outside the lower conductive rod.

[0013] In some embodiments, the first protection sleeve and the second protection sleeve are vertically overlapped and sleeved, and there is a gap between the two, so that the spring pin structure can adaptively adjust the length of the electric connection component.

[0014] In some embodiments, the first protection sleeve includes a flange plate and a sleeve, the flange plate is fixed at the end of the positioning hole, and the sleeve is disposed in the mounting hole of the shaft portion; there is a gap between the lower end surface of the flange plate and the top surface of the shaft portion.

[0015] In some embodiments, vent holes are provided on the flange, one end of which is communicated with a gas source and the other end is communicated with the mounting hole to ventilate or evacuate the central chamber of the elastic membrane, thereby changing the load applied to the central chamber.

[0016] In some embodiments, the radial length of the central chamber is 10 - 50 mm.

[0017] In some embodiments, a fixing hole is provided in the central chamber of the elastic membrane, the conduction rod passes through the fixing hole and is connected to the lower conductive rod, and the disc seat is bonded to the outer side of the elastic membrane.

[0018] In some embodiments, a limiting groove is provided on the outer side of the elastic membrane, the limiting groove is concentric with the fixing hole, and the thickness of the disc seat matches the depth of the limiting groove, and the disc seat is snap - fitted in the limiting groove.

[0019] In some embodiments, the elastic membrane is made of silicone rubber or neoprene and contains silver powder greater than or equal to 50%.

[0020] In some embodiments, the Shore hardness of the elastic membrane is 55 - 65.

[0021] In some embodiments, an annular groove is provided on the bottom surface of the elastic membrane, and the inside of the annular groove is bonded to a matching annular conductive sheet.

[0022] In some embodiments, the annular groove is provided at the partition rib between adjacent chambers, and its depth is 0.2 - 0.5 mm.

[0023] 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, and they are evenly distributed.

[0024] In some embodiments, the conductive blocks are provided at the partition rib between adjacent chambers.

[0025] In some embodiments, the electrochemical mechanical polishing head further includes a pneumatic control assembly, which is communicated with the central chamber and the annular chamber of the elastic membrane to control the load applied to each chamber of the elastic membrane.

[0026] According to the second aspect of the embodiments of the present application, an electrochemical mechanical polishing device is provided, which includes: A polishing disc for fixing a polishing pad; A liquid supply assembly for supplying polishing liquid towards the surface of the polishing pad; And the above - mentioned electrochemical mechanical polishing head for loading a wafer and abutting it against the surface of the polishing pad; A power supply, one end of which is connected to the electrical connection component, and the other end of which 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.

[0027] In some embodiments, the polishing pad is configured with a plurality of through holes to retain the polishing liquid on the surface of the polishing pad.

[0028] In some embodiments, the positive electrode of the power supply is connected to the electrochemical mechanical polishing head, and its negative electrode is connected to the polishing liquid on the surface of the polishing pad.

[0029] According to the third aspect of the embodiments of the present application, an electrochemical mechanical polishing method is provided. Using the above-described electrochemical mechanical polishing device, while the electrochemical mechanical polishing head performs an electrochemical reaction on the wafer, the elastic film performs multi-zone pressure control on the wafer to obtain a wafer that meets the process requirements.

[0030] During the wafer polishing process, the pressure in the annular chamber of the elastic film is greater than the pressure in the central chamber.

[0031] In some embodiments, the annular chamber of the elastic film is under positive pressure, and the central chamber is under atmospheric pressure or negative pressure.

[0032] The beneficial effects of the present invention include: a. The provided electrochemical mechanical polishing head is internally configured with an electrical connection component. The electrical connection component is configured with a flexible member that can automatically adjust its vertical length to adapt to the deformation of the elastic film, thereby forming a stable electric field between the elastic film and the polishing liquid. b. The electrical connection component is configured with a detachable spring pin structure that can dynamically adjust the expansion and contraction of the spring according to the loading of the elastic film to adjust the length of the electrical connection component. c. The conduction disk of the electrical connection component is bonded to the inner side of the bottom plate of the elastic film through a conductive adhesive to conduct the current to the wafer to be polished via the elastic film. d. The bottom surface of the disk seat of the conduction disk is configured with a concavo-convex structure, and the concavo-convex structure is an annular groove to increase the friction coefficient of the bottom surface of the disk seat, thereby increasing the bonding reliability between the conduction disk and the elastic film. e. The central chamber of the elastic film is configured with a positioning groove, and the depth of the positioning groove is at least 1 / 3 of the thickness of the bottom plate to increase the flexibility of the bottom of the central chamber. At the same time, the adhesive can be applied at the contact between the disk seat and the inner side wall of the positioning groove, which is also beneficial to enhancing the bonding strength between the two. f. The electrical connection component further includes a protection component that is disposed outside the upper conductive rod and the lower conductive rod to prevent liquid from entering the interior of the electrical connection component. At the same time, the protection component can prevent other metal components from connecting to the upper conductive rod and the lower conductive rod to cause a short circuit and affect the normal use of the electrochemical mechanical polishing head. g. The first protective sleeve of the protection component is arranged on the outer side of the upper conductive rod, and the second protective sleeve is arranged on the outer side of the lower conductive rod. The first protective sleeve and the second protective sleeve are vertically overlapped and sleeved, and there is a gap 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 disturbing the free expansion and contraction of the spring; h. The conductive adhesive for bonding the conductive disk and the elastic film is a silicone-based conductive adhesive, which has high temperature resistance and can maintain good adhesiveness in the range of -50°C to 200°C to adapt to the working environment of electrochemical mechanical polishing; i. The first protective sleeve includes a flange and a sleeve, and the two are integrally formed to form a tubular structure to protect the upper conductive rod 51; there is a gap between the lower end surface of the flange and the top surface of the shaft part; when the bearing disk moves up and down vertically, the top surface of the shaft part will not abut against the flange of the first protective sleeve to avoid component interference during the operation of the electrochemical polishing head; j. The flange is provided with a vertical ventilation hole, one end of which is communicated with the gas source and the other end is communicated with the installation hole to ventilate or evacuate the central chamber of the elastic film, thereby changing the load applied to the central chamber.

[0033] That is, during electrochemical mechanical polishing, the pressure of each chamber of the elastic film can be controlled to adjust the polishing load applied to the wafer surface, and combined with the electrochemical reaction, the material removal rate of the wafer surface can be comprehensively regulated; k. The elastic film is made of silicone rubber or neoprene, and contains silver powder greater than or equal to 50% to ensure the conductivity of the elastic film; l. The Shore hardness of the elastic film is 55-65, so that the elastic film has a certain flexibility to facilitate the loading of the wafer by suction; m. The surface of the bottom plate of the elastic film 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 film with conductive adhesive to improve the conductivity uniformity of the elastic film without affecting its own flexibility; n. The annular grooves are arranged at the partition ribs between adjacent chambers of the elastic film, which weakens the stress concentration at the partition ribs to a certain extent, inhibits the pressure coupling between adjacent chambers, and ensures the accuracy of the polishing pressure applied to each chamber of the elastic film; o. The radial width of the annular groove is at least 2-3 times the wall thickness of the partition rib, and its depth is 0.2-0.5 mm to weaken the stress concentration at the partition rib; A plurality of conductive blocks are embedded in the bottom surface of the elastic membrane to improve the conductive uniformity of the elastic membrane; the conductive blocks are circular, rectangular, triangular and / or elliptical, and are arranged at the partition ribs of adjacent chambers to weaken the stress concentration of the elastic membrane at the partition ribs, inhibit the pressure coupling between adjacent chambers, and ensure the accuracy of the polishing pressure applied to each chamber of the elastic membrane. Description of the Drawings

[0034] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments recorded in the embodiments of the present application. For those of ordinary skill in the art, other drawings can also be obtained according to these drawings.

[0035] Figure 1 It is a schematic diagram of an electrochemical mechanical polishing head provided by an embodiment of the present invention; Figure 2 It is a schematic diagram of an electrochemical mechanical polishing device provided by an embodiment of the present invention; Figure 3 is Figure 1 The partial enlarged view of A in; Figure 4 It is a schematic diagram of an upper conductive rod provided by an embodiment of the present invention; Figure 5 It is a schematic diagram of a lower conductive rod provided by an embodiment of the present invention; Figure 6 is Figure 1 The schematic diagram of the bullet pin structure in the embodiment; Figure 7 It is a schematic diagram of an electrical connection component provided by an embodiment of the present invention; Figure 8 It is a schematic diagram of a conduction disk provided by an embodiment of the present invention; Figure 9 is Figure 1 The partial schematic diagram of the elastic membrane in the embodiment; Figure 10 It is a schematic diagram of a first protective sleeve provided by an embodiment of the present invention; Figure 11 It is the bottom view of the elastic membrane provided by an embodiment of the present invention; Figure 12 It is the bottom view of the elastic membrane provided by another embodiment of the present invention; Figure 13 It is a schematic diagram of the conductive block arranged inside the bottom plate provided by an embodiment of the present invention; Figure 14 It is a schematic diagram of an electrochemical mechanical polishing head provided by another embodiment of the present invention; Figure 15Yes Figure 14 Partial enlarged view at position B in the middle; Figure 16 Yes Figure 14 Partial schematic view of the central chamber of the elastic membrane in the embodiment; Figure 17 Yes Figure 14 Schematic view of the second protective sleeve in the embodiment. Detailed implementation manners

[0036] To enable those skilled in the art to better understand the technical solutions in the embodiments of the present application, the following will clearly and completely describe the technical solutions in the embodiments of the present application in conjunction with the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the embodiments of the present application, all other embodiments obtained by those of ordinary skill in the art shall fall within the scope protected by the embodiments of the present application.

[0037] The terms used in the present application are only for the purpose of describing specific embodiments, and are not intended to limit the present application. The singular forms "a", "the" and "said" used in the present 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" used herein refers to and includes any or all possible combinations of one or more of the associated listed items.

[0038] It should be understood that although the terms "first", "second", "third", etc. may be used in the present application to describe various information, such information should not be limited to these terms. These terms are only used to distinguish the same type of information from each other. For example, without departing from the scope of the present 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, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present application, "a plurality" means two or more, unless otherwise specifically defined.

[0039] Figure 1 It is a schematic view of an electrochemical mechanical polishing head 100 provided by an embodiment of the present invention, which is used for polishing superhard materials such as silicon carbide. The electrochemical mechanical polishing head 100 includes: A coupling disk 10, which is of a disk-like structure. A connecting flange is provided above the coupling disk 10 to connect the output shaft of the driving motor, thereby driving the coupling disk 10 and the components connected thereto to rotate around the axis; a vertical positioning hole 11 is provided at the center of the coupling disk 10; A carrier plate 20 is provided with a shaft portion 21 above it. The shaft portion 21 is arranged to match the positioning hole 11 of the coupling plate 10, that is, the shape and size of the shaft portion 21 match those of the positioning hole 11, and the shaft portion 21 is slidably connected to the inside of the positioning hole 11. At the same time, the coupling plate 10 is connected to the carrier plate 20 through an annular film 60, enabling the carrier plate 20 to rotate and / or move in the vertical direction along 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. A conductive elastic film 30 is arranged below the carrier plate 20 and is used to load the wafer to be processed. A retaining ring 40 is arranged below the carrier plate 20 and on the outer peripheral side of the elastic film 30 to prevent the wafer to be polished from slipping out of the inside of the electrochemical mechanical polishing head 100. An electrical connection component 50 is vertically arranged inside the mounting hole 211. Furthermore, one end of the electrical connection component 50 is Figure 2 connected to the power supply 200 shown. The other end of the electrical connection component 50 is connected to the central chamber 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.

[0040] Generally, the positive electrode of the power supply 200 is connected to the wafer through the electrical connection component 50, so that the wafer enters the polishing liquid as an anode. After the wafer is energized, an oxidation reaction occurs, and the metal ions on its surface are ionized and dissolved to achieve material removal.

[0041] During the electrochemical action, the abrasive grains in the polishing liquid physically grind the surface of the wafer to remove the passivation film or softened layer generated by the electrochemical reaction, exposing the fresh surface for continuous dissolution.

[0042] To solve problems such as wire pulling and tearing existing in the existing electrochemical mechanical polishing head, at least part 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 film 30, and further form a stable electric field between the elastic film 30 and the polishing liquid to ensure the reliable operation of the electrochemical mechanical polishing head 100.

[0043] Figure 3 is Figure 1 a partial enlarged view of part A. The electrical connection component 50 is arranged in the mounting hole 211 of the shaft portion 21. The bottom of the electrical connection component 50 is connected to the elastic film 30, and the top of the electrical connection component 50 is connected to the power supply 200 to deliver current to the wafer loaded below the elastic film 30 through the electrical connection component 50 and the conductive elastic film 30.

[0044] Furthermore, the electrical connection component 50 includes an upper conductive rod 51 and a lower conductive rod 52, as Figure 3As shown, a spring pin structure 53 is detachably connected between the two to adjust the length of the electrical connection assembly 50.

[0045] Figure 3 In this case, the spring pin structure 53 includes a spring 531 and a pin shaft 532. The two are clamped together and abutted in the grooves on the opposite surfaces of the upper conductive rod 51 and the lower conductive rod 52. A part of the pin shaft 532 is inserted into the interior of the spring 531 to play a role in connection and positioning. That is, the diameter of the lower part of the pin shaft 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 shaft 532.

[0046] Specifically, the bottom of the upper conductive rod 51 is configured with Figure 4 the first groove 511 shown to define the position of the pin shaft 532 and prevent it from deflecting in the vertical direction; the top of the lower conductive rod 52 is configured with Figure 5 the second groove 521 shown for placing the spring 531. When the spring 531 is in a relaxed state, the whole of the 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; to prevent the spring 531 from protruding out of the second groove 521 and causing the spring pin structure 53 to deflect.

[0047] Figure 5 In the embodiment shown, the second groove 521 is an end-opening groove, and its top is configured with a limiting platform 5211 to play a role in clamping and limiting.

[0048] To ensure the reliability of the fixation of the spring pin structure 53, the pin shaft 532 is configured with an annular limiting protrusion 5321. As Figure 6 shown, the limiting protrusion 5321 of the pin shaft 532 is arranged 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 spring pin structure 53, that is, to determine the maximum length of the spring pin structure 53 along the axial direction, and further prevent the spring pin structure 53 from expanding and contracting excessively and affecting the normal operation of the electrochemical polishing head 100.

[0049] Figure 7 This is a schematic diagram of the electrical connection assembly 50 provided by an embodiment of the present invention. The electrical connection assembly 50 further includes a protection assembly 54, which is arranged 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 protection 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.

[0050] Further, the protection component 54 includes a first protective sleeve 541 and a second protective sleeve 542. Among them, the first protective sleeve 541 is disposed outside the upper conductive rod 51, and the second protective sleeve 542 is disposed outside the lower conductive rod 52.

[0051] 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, and the length of the second protective sleeve 542 is greater than the length of the lower conductive rod 52, so that the second protective sleeve 542 can extend upward 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, and there is a gap between the two, so that the spring pin structure 53 can adaptively adjust the length of the electrical connection component 50, thereby preventing the first protective sleeve 541 and the second protective sleeve 542 from interfering with each other and disturbing the free expansion and contraction of the spring 531.

[0052] Further, above the upper conductive rod 51 is configured with Figure 7 the conductive terminal 56 shown, which is connected to the positive pole of the power supply 200, and the current can be transmitted downward through the conductive terminal 56; below the lower conductive rod 52 is configured with a conduction disk 55, and the conduction disk 55 includes Figure 8 the conduction rod 551 and the disk base 552 shown, which are integrally formed. Among them, the conduction rod 551 is threadedly connected to the lower conductive rod 52, and the disk base 552 is adhesively bonded to the elastic film 30 by glue, so that the current can follow the conductive terminal 56, the upper conductive rod 51, the spring pin structure 53, the lower conductive rod 52 and the conduction disk 55, conduct to the elastic film 30, and finally conduct the current to the wafer loaded on the elastic film 30.

[0053] Figure 1 In the illustrated embodiment, there are multiple chambers in the elastic film 30. Specifically, the elastic film 30 includes a circular central chamber 38, which is located at the center of the elastic film 30; the elastic film 30 further includes at least one annular chamber, and this annular chamber is located outside the central chamber 38; among them, the disk base 552 of the conduction disk 55 is adhesively bonded to the central chamber 38 of the elastic film 30.

[0054] In the present invention, the elastic film 30 includes a bottom plate 31 and partition ribs, and the partition ribs extend upward from the bottom plate 31 to form independent chambers, so as to apply different pressures to each chamber, thereby realizing multi-zone polishing pressure control.

[0055] Specifically, the electrochemical mechanical polishing head 100 further includes a pneumatic control component 70, such as Figure 2As shown, it is connected to the central chamber 38 and the annular chamber of the elastic membrane 30 to control the polishing load applied by each chamber of the elastic membrane 30. The air pressure control assembly 70 generally includes functional devices such as a proportional valve, a flow meter, a pressure sensor, and a controller. For the connection relationship of each functional device, please refer to Patent CN110977750A, which will not be elaborated here.

[0056] 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, so as to combine with the electrochemical reaction and comprehensively control the material removal rate of the wafer surface.

[0057] Figure 9 is Figure 1 A partial schematic diagram of the elastic membrane 30 in the embodiment. A positioning groove 311 is arranged on the inner side surface of the central chamber 38, that is, a positioning groove 311 is arranged on the inner side surface of the bottom plate 31 of the elastic membrane 30 for adhesively fixing the disk seat 552. It can be understood that the shape and size of the disk seat 552 match the shape and size of the positioning groove 311 to accurately connect the conduction disk 55 to the central position of the elastic membrane 30, so that the current is transmitted from the center of the elastic membrane 30 to the outside, which is beneficial to ensuring the uniformity of the current distribution on the elastic membrane 30.

[0058] To ensure the conductivity between the conduction disk 55 and the elastic membrane 30, the adhesive used is a conductive adhesive. In some embodiments, the conductive adhesive for bonding the conduction disk 55 and the elastic membrane 30 is a silicone-based conductive adhesive, such as Dow Corning SE 4420 conductive adhesive. It has good flexibility, is suitable for the application of dynamic loads, and this conductive adhesive has high temperature resistance. It can maintain good adhesiveness in the range of -50°C to 200°C to adapt to the working environment of electrochemical mechanical polishing. Specifically, during electrochemical mechanical polishing, a large amount of heat will be generated on the wafer, and these heats will be conducted to the elastic membrane 30 and the conduction disk 55. If the adhesive cannot withstand high temperatures, it will affect the reliability of the bonding between the conduction disk 55 and the elastic membrane 30, and even the electrical connection assembly 50 may have an open circuit situation, thereby affecting the normal operation of the electrochemical mechanical polishing head 100.

[0059] In some embodiments, the bonding surface of the disk seat 552 is provided with a concavo-convex structure, such as Figure 8 shown, to increase the reliability of the bonding between the disk seat and the elastic membrane. Figure 8 In, the concavo-convex structure is an annular groove to increase the friction coefficient of the bottom surface of the disk seat 552, thereby increasing the reliability of the bonding between the conduction disk 55 and the elastic membrane 30.

[0060] Figure 9In [the invention], 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 chamber 38. Meanwhile, the adhesive can be applied at the contact between the disc seat 552 and the inner sidewall of the positioning groove 311, which also helps to enhance the adhesive strength between the two.

[0061] In the present invention, the radial length of the central chamber 38 is 10 - 50 mm, while the radial dimension of the positioning groove 311 is 5 - 30 mm to ensure the flexibility of the central chamber 38 of the elastic membrane 30.

[0062] Figure 10 is a 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. Among them, the flange 5411 is fixed to the end of the positioning hole 11. As Figure 3 shown, the sleeve 5412 is disposed in the mounting hole 211 of the shaft portion 21.

[0063] Further, a gap 57 is provided between the lower end surface of the flange 5411 and the top surface of the shaft portion 21. When the bearing plate 20 moves up and down vertically, the top surface of the shaft portion 21 will not abut against the flange 5411 of the first protective sleeve 541 to avoid component interference during the operation of the electrochemical polishing head 100.

[0064] Figure 10 In [the invention], a vertical ventilation hole 5413 is configured on the flange 5411. One end thereof is communicated with the gas source, and the other end is communicated with the mounting hole 211 to ventilate or evacuate the central chamber 38 of the elastic membrane 30, thereby changing the load applied to the central chamber 38.

[0065] That is, during electrochemical mechanical polishing, the pressure of the central chamber 38 can be controlled to adjust the polishing load applied to the surface of the wafer, so that mechanical polishing and electrochemical reaction are combined to comprehensively control the material removal rate of the wafer surface.

[0066] In the present invention, the elastic membrane 30 is made of silicone rubber or neoprene, and contains silver powder greater than or equal to 50% to ensure the conductivity of the elastic membrane 30. Specifically, when the elastic membrane 30 is molded, the silver powder needs to be uniformly blended into the liquid rubber, which is beneficial to the uniformity of the conductivity of the elastic membrane 30.

[0067] Further, the Shore hardness of the elastic membrane 30 is 55 - 65, so that the elastic membrane 30 has a certain flexibility to facilitate the loading of the wafer by suction.

[0068] Figure 11It is a bottom view of the elastic film 30 provided by an embodiment of the present invention. An annular groove 32 is provided on the bottom surface of the elastic film 30, that is, an annular groove 32 is provided on the lower surface of the bottom plate 31.

[0069] Furthermore, the number of the annular grooves 32 is multiple, and they are concentrically arranged on the bottom surface of the elastic film 30. A rectangular groove 33 is also configured on the surface of the bottom plate 31 to communicate adjacent annular grooves 32.

[0070] 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 to further improve the conductivity uniformity of the elastic film 30.

[0071] It should be noted that the annular conductive sheet and the rectangular conductive sheet are metal foils, and they are bonded to the bottom surface of the elastic film 30 with conductive adhesive to improve the conductivity uniformity of the elastic film 30 without affecting the flexibility of the elastic film 30 itself.

[0072] In the present invention, the depths of the annular groove 32 and the rectangular groove 33 are 0.2 - 1.5 mm; preferably, the depths of the annular groove 32 and the rectangular groove 33 are 0.2 - 0.5 mm.

[0073] In some embodiments, the annular groove 32 is provided at the partition rib between adjacent chambers of the elastic film 30, which weakens the stress concentration at the partition rib of the elastic film 30 to a certain extent, inhibits the pressure coupling between adjacent chambers, and ensures the accuracy of the polishing pressure applied to each chamber of the elastic film 30.

[0074] Specifically, the radial width of the annular groove 32 is at least 2 - 3 times the wall thickness of the partition rib, and its depth is 0.2 - 0.5 mm to weaken the stress concentration at the partition rib.

[0075] Figure 12 It is a bottom view of the elastic film 30 provided by another embodiment of the present invention. In this embodiment, a plurality of circular conductive blocks 34 are embedded in the bottom surface of the elastic film 30. The conductive blocks 34 are metal sheets to improve the conductivity uniformity of the elastic film 30. That is, a groove for bonding the conductive blocks 34 is configured on the bottom surface of the bottom plate 31 of the elastic film 30, and the conductive blocks 34 are bonded to the groove on the bottom surface of the bottom plate 31 with conductive adhesive.

[0076] It can be understood that the conductive blocks 34 can also be rectangular, triangular, and / or elliptical, and they are evenly distributed.

[0077] In some embodiments, the conductive blocks 34 are provided at the partition rib between adjacent chambers to weaken the stress concentration at the partition rib of the elastic film 30, inhibit the pressure coupling between adjacent chambers, and ensure the accuracy of the polishing pressure applied to each chamber of the elastic film 30.

[0078] 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, as Figure 13 shown. With such an arrangement, the groove for placing the conductive block 34 is provided 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 to form crystals, and the falling of these crystals may cause wafer scratches.

[0079] Figure 14 is a schematic diagram of an electrochemical mechanical polishing head 100 provided by another embodiment of the present invention. Figure 15 is Figure 14 a partial enlarged view of B in Figure 1 shown. The electrochemical mechanical polishing head 100 in this embodiment is basically the same as that

[0080] shown. The following focuses on the differences between the two: the connection manner between the electrical connection component 50 and the elastic membrane 30.

[0080] In this embodiment, a fixing hole 35 as Figure 16 shown is arranged in the central chamber 38 of the elastic membrane 30, that is, the fixing hole 35 is arranged on the bottom plate 31. The conducting rod 551 of the conducting disk 55 passes through the fixing hole 35 and is threadedly connected to the lower guide rod 52. The disk seat 552 of the conducting disk 55 is bonded to the outer side of the elastic membrane 30, as Figure 15 shown.

[0081] Figure 16 In the embodiment as

[0082] shown, a limiting groove 36 is arranged on the outer side of the elastic membrane 30. The limiting groove 36 is concentric with the fixing hole 35. Moreover, the thickness of the disk seat 552 matches the depth of the limiting groove 36, and the disk seat 552 is clamped in the limiting groove 36 so that the bottom surface of the disk seat 552 is flush with the bottom surface of the bottom plate 31 of the elastic membrane 30.

[0082] To ensure the reliability of the connection between the conducting disk 55 and the elastic membrane 30, a circular protrusion 37 is arranged in the central chamber 38 of the elastic membrane 30, which extends upward from the end surface of the fixing hole 35. At the same time, a clamping groove 5421 is arranged at the bottom of the second protective sleeve 542, as Figure 17 shown, so that the circular protrusion 37 of the elastic membrane 30 is arranged in the clamping groove 5421 of the second protective sleeve 542 to further ensure the reliability of the fixation between the two.

[0083] At the same time, the present invention provides an electrochemical mechanical polishing device 1000, and its schematic diagram is as Figure 2 shown. The electrochemical mechanical polishing device 1000 includes: A polishing disk 300 for fixing a polishing pad 400; specifically, the polishing pad 400 is arranged above the polishing disk 300 so that the polishing pad 400 can rotate synchronously with the polishing disk 300.

[0084] A liquid supply assembly 500 is disposed above the polishing pad 300 for supplying polishing liquid toward the surface of the polishing pad 400; and Figure 2 or Figure 14 The shown electrochemical mechanical polishing head 100 is used for loading a wafer and abutting the wafer against the surface of the polishing pad 400; A power supply 200 has one end connected to the electrical connection assembly 50 of the electrochemical mechanical polishing head 100 and the other end connected to the polishing pad 400, such that the wafer to be polished is in the electric field formed between the elastic film 30 and the polishing liquid.

[0085] In the present invention, the polishing pad 400 is configured with a plurality of vertical through holes to retain the polishing liquid on the surface of the polishing pad 400. The polishing liquid is an electrolyte containing abrasive grains, wherein the contained abrasive grains are SiO 2 , CeO 2 and / or Al 2 O 3 etc., so as to combine the electrochemical reaction with the mechanical polishing, improve the material removal rate of the wafer, adapt to the polishing of materials with higher hardness, and improve the polishing efficiency of the wafer.

[0086] Figure 2 In the shown electrochemical mechanical polishing apparatus 1000, the positive electrode of the power supply 200 is connected to the electrical connection assembly 50 of the electrochemical mechanical polishing head 100, and its negative electrode is connected to the polishing liquid on the surface of the polishing pad 400, such that the wafer to be processed is in the stable electric field formed between the elastic film 30 and the polishing liquid, so as to realize the material removal on the surface of the wafer under the combined action of the electrochemical action and the chemical mechanical polishing, efficiently polish superhard materials, and improve the polishing efficiency.

[0087] In addition, the present invention also provides an electrochemical mechanical polishing method, which uses Figure 2 the shown electrochemical mechanical polishing apparatus 1000. When polishing the wafer, while the electrochemical mechanical polishing head 100 performs an electrochemical reaction on the wafer, the elastic film 30 performs multi-zone pressure control on the wafer to obtain a wafer meeting the process requirements.

[0088] During the wafer polishing process, the pressure in the annular chamber of the elastic film 30 is greater than the pressure in the central chamber 38 to evenly balance the hard contact between the conduction disk 55 in the central chamber 38 and the wafer, and ensure that the comprehensive material removal rates in the circumferential direction of the wafer are substantially the same.

[0089] In some embodiments, the annular chamber of the elastic film 30 is at a positive pressure, while the central chamber 38 is at an atmospheric pressure or a negative pressure, so as to reasonably configure the pressures of the respective chambers of the elastic film 30, adjust the stress concentration of the conduction disk 55 and the influence of the non-uniform current applied by the elastic film 30 on the wafer on the material removal rate of the wafer surface, and obtain a wafer meeting the process requirements.

[0090] Those of ordinary skill in the art will appreciate that the units and method steps of the examples described in conjunction with the embodiments disclosed herein can be implemented with electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are executed in hardware or software depends on the specific application and design constraints of the technical solution. A person skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered to exceed the scope of the embodiments of this application.

[0091] The above embodiments are only used to illustrate the embodiments of this application, rather than to limit the embodiments of this application. Those of ordinary skill in the relevant technical field can also make various changes and modifications without departing from the spirit and scope of the embodiments of this application. Therefore, all equivalent technical solutions also belong to 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: A coupling plate, with a positioning hole at the 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 film is disposed below the carrier plate and is used to load the wafers to be processed; A retaining ring, disposed below the carrier plate and located on the outer peripheral side of the elastic membrane; An electrical connection assembly is vertically arranged 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 a 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 liquid; At least part 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.

2. The electrochemical mechanical polishing head according to claim 1, characterized in that: 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 mutually clamped as a whole and abut against the grooves on the opposite surfaces of the upper conductive rod and the lower conductive rod.

3. The electrochemical mechanical polishing head according to claim 2, characterized in that: A conducting plate is arranged below the lower conducting rod, and the conducting plate comprises a conducting rod and a plate seat, which are integrally formed; the conducting rod is connected to the lower conducting rod, and the plate seat is bonded to the elastic film by conductive adhesive.

4. The electrochemical mechanical polishing head according to claim 3, characterized in that: The elastic membrane has a plurality of 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.

5. The electrochemical mechanical polishing head according to claim 4, 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.

6. The electrochemical mechanical polishing head according to claim 2, characterized in that: 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.

7. The electrochemical mechanical polishing head according to claim 6, characterized in that: 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.

8. The electrochemical mechanical polishing head according to claim 6, 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 arranged between the lower end surface of the flange and the top surface of the shaft.

9. The electrochemical mechanical polishing head according to claim 8, 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 chamber of the elastic membrane, thereby changing the load applied to the central chamber.

10. The electrochemical mechanical polishing head according to claim 9, characterized in that: The radial length of the central chamber is 10-50 mm.

11. The electrochemical mechanical polishing head according to claim 4, characterized in that: The central chamber 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 bonded to the outer side of the elastic membrane.

12. The electrochemical mechanical polishing head according to claim 11, characterized in that: A limiting groove is arranged on the outer side of the elastic membrane, the limiting groove is arranged concentrically with the fixing hole, and the thickness of the disc seat matches the depth of the limiting groove, and the disc seat is clamped in the limiting groove.

13. 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.

14. The electrochemical mechanical polishing head according to claim 1, characterized in that: The elastic film has a Shore hardness of 55-65.

15. The electrochemical mechanical polishing head according to claim 1, characterized in that: The bottom surface of the elastic film is provided with an annular groove, and the inside of the annular groove is bonded to a matching annular conductive sheet.

16. The electrochemical mechanical polishing head according to claim 15, characterized in that: The annular groove is arranged at the dividing ribs of adjacent chambers, and its depth is 0.2-0.5 mm.

17. The electrochemical mechanical polishing head according to claim 1, characterized in that: 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.

18. The electrochemical mechanical polishing head according to claim 17, characterized in that: The conductive blocks are arranged at the dividing ribs of adjacent chambers.

19. The electrochemical mechanical polishing head according to claim 4, characterized in that: It also includes an air pressure control component which is communicated with the central chamber and the annular chamber of the elastic membrane to control the load applied by each chamber of the elastic membrane.

20. An electrochemical mechanical polishing device, characterized in that: include: A polishing disc, used to fix the polishing pad; A liquid supply component, used for supplying polishing liquid toward the surface of the polishing pad; and an electrochemical mechanical polishing head according to any one of claims 1 to 19, for loading a wafer and bringing it into contact with a 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.

21. The electrochemical mechanical polishing device according to claim 20, characterized in that: The polishing pad is provided with a plurality of through holes so as to retain the polishing liquid on the surface of the polishing pad.

22. The electrochemical mechanical polishing device according to claim 20, characterized in that: 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.

23. An electrochemical mechanical polishing method, characterized in that: When the electrochemical mechanical polishing device according to claim 20 is used, while the electrochemical mechanical polishing head performs 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.

24. The electrochemical mechanical polishing method according to claim 23, 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.

25. The electrochemical mechanical polishing method according to claim 24, 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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