Retaining Rings and Carrier Heads for Chemical Mechanical Polishing

Abstract

The present invention discloses a retaining ring and a carrier head for chemical mechanical polishing, and relates to the field of semiconductor manufacturing technology. The retaining ring comprises a retaining ring body, and the lower end surface of the retaining ring body is provided with a first groove and a second groove, wherein the first grooves are multiple and spaced apart, and the second grooves are arranged between adjacent first grooves; the polishing liquid used for chemical mechanical polishing enters the interior of the retaining ring via the first groove and the second groove, and the used polishing liquid is discharged to the outside of the retaining ring via the second groove.

Description

Technical Field

[0001] The embodiments of the present application relate to the field of semiconductor manufacturing technology, and in particular to a retaining ring and a carrier head for chemical mechanical polishing. Background Art

[0002] The integrated circuit industry is the core of the information technology industry and plays a key role in promoting the transformation and upgrading of the manufacturing industry towards digitalization and intelligence. Chips are the carriers of integrated circuits, and chip manufacturing involves process flows such as integrated circuit design, wafer manufacturing, wafer processing, electrical measurement, cutting packaging and testing. Among them, chemical mechanical polishing is one of the five core processes in the wafer manufacturing process.

[0003] Chemical Mechanical Polishing (CMP) is an ultra-precision surface processing technology for global flattening. Chemical mechanical polishing usually involves sucking the wafer onto the bottom surface of a carrier head, with the side of the wafer with the deposition layer abutting against the upper surface of the polishing pad. The carrier head rotates in the same direction as the polishing pad under the actuation of the drive assembly and applies a downward load to the wafer; the polishing liquid is supplied to the upper surface of the polishing pad and distributed between the wafer and the polishing pad, so that the wafer completes the chemical mechanical polishing of the wafer under the combined action of chemistry and mechanics.

[0004] The carrier head is a key component of the CMP system. For example, the carrier head provided by patent CN110524412A has a retaining ring at its lower end, which is mainly used to limit the wafer during the polishing process to prevent it from slipping out of the carrier head under the action of lateral force; a groove is provided at the bottom end of the retaining ring to transport the polishing liquid to between the polishing pad and the wafer; in addition, the retaining ring can also participate in the regulation of polishing pressure, that is, by adjusting the pressure of the retaining ring to improve the unevenness of the wafer removal rate.

[0005] The groove design at the bottom of the retaining ring is crucial, and it is usually a straight groove structure; if the groove width is set too small, it will affect the speed and amount of polishing liquid entering, and thus affect the removal rate of the wafer surface; if the groove width is set too large, the polishing liquid almost does not stay inside the carrier head, that is, the polishing liquid enters through one side of the carrier head and then flows out from the other side of the carrier head, and almost does not participate in chemical mechanical polishing, resulting in a reduced utilization rate of the polishing liquid. Summary of the invention

[0006] In view of this, an embodiment of the present application provides a retaining ring and a carrier head for chemical mechanical polishing to at least partially solve the above problems.

[0007] According to a first aspect of an embodiment of the present application, a retaining ring for chemical mechanical polishing is provided, which includes a retaining ring body, wherein the lower end surface of the retaining ring body is provided with a first groove and a second groove, wherein the first grooves are multiple and spaced apart, and the second grooves are arranged between adjacent first grooves; the polishing liquid used for chemical mechanical polishing enters the interior of the retaining ring via the first groove and the second groove, and the used polishing liquid is discharged to the outside of the retaining ring via the second groove.

[0008] In some embodiments, the number of the first grooves is less than the number of the second grooves.

[0009] In some embodiments, the number of second grooves disposed between adjacent first grooves is 3 to 8.

[0010] In some embodiments, the first groove is extended along the lower end surface of the retaining ring body, and includes a liquid inlet channel and a liquid outlet channel; the liquid inlet channel is a rectangular groove, which extends from the outer wall of the retaining ring body toward the inside; the liquid outlet channel is a conical groove, which faces the inner wall of the retaining ring body and is arranged opposite to the liquid inlet channel.

[0011] In some embodiments, the width of the liquid outlet channel gradually increases from the outside to the inside.

[0012] In some embodiments, the opening of the liquid outlet channel forms an angle of 80 to 170 degrees.

[0013] In some embodiments, a main channel is arranged between the liquid inlet channel and the liquid outlet channel, and the main channel includes a tapered section and a straight section; the tapered section is connected to the liquid inlet channel, and its width gradually increases from the outside to the inside; the straight section extends inward from the tapered section, and its width is greater than the opening width of the liquid outlet channel.

[0014] In some embodiments, a feedback channel is further provided between the liquid inlet channel and the liquid outlet channel, and the number of the feedback channels is two and they are symmetrically arranged on both sides of the main channel.

[0015] In some embodiments, the feedback channel, the main channel, the liquid inlet channel and the liquid outlet channel are interconnected, and the width of the feedback channel is 1 to 1.5 times the width of the liquid inlet channel.

[0016] In some embodiments, the width of the liquid inlet channel is 3.1-3.5 mm.

[0017] In some embodiments, the opening size of the liquid outlet channel close to the outer side wall of the retaining ring body is 1.5 times that of the liquid inlet channel.

[0018] In some embodiments, the first groove is a symmetrical structure, and its symmetry axis passes through the center of the retaining ring.

[0019] In some embodiments, the width of the first groove is 0.8 times the radial dimension of the retaining ring body.

[0020] In some embodiments, the second groove is a straight groove, and a central axis thereof points to the center of the retaining ring.

[0021] In some embodiments, the second groove is an oblique groove, and the angle between the line between the inner port and the center of the retaining ring and the central axis of the second groove is 45-60°.

[0022] In some embodiments, the first groove is inclined, and the angle between the line between the inner port of the liquid outlet channel and the center of the retaining ring and the central axis of the first groove is 3-15°.

[0023] In some embodiments, the width of the liquid inlet channel is equal to the width of the second groove.

[0024] In some embodiments, a depth of the first trench is greater than or equal to a depth of the second trench.

[0025] In some embodiments, the depth of the first groove is 3.5-4.5 mm.

[0026] In some embodiments, the bottom surface of the first groove has a slope, and the depth of the first groove gradually decreases from the outside to the inside.

[0027] In some embodiments, the difference between the depth of the first groove on the outer side wall and the depth of the first groove on the inner side wall is 0.5-1 mm.

[0028] According to a first aspect of an embodiment of the present application, there is provided a carrier head for chemical mechanical polishing, comprising: Coupling plate; A bearing plate, arranged below the coupling plate; An elastic membrane, disposed below the carrying plate; The retaining ring as described above is arranged below the carrier plate and located on the outer peripheral side of the elastic membrane.

[0029] The beneficial effects of the present invention include: a. The number of the first grooves on the lower end surface of the retaining ring is less than the number of the second grooves to balance the efficiency of entry and discharge of the polishing liquid, promote the flow and mixing of the polishing liquid inside the retaining ring, and improve the utilization rate of the polishing liquid; b. The width of the liquid outlet channel of the first groove gradually increases from the outside to the inside, that is, the liquid outlet channel has a tapered mouth structure to facilitate rapid diffusion of the polishing liquid inside the retaining ring; c. The main channel of the first groove configuration is disposed between the liquid inlet channel and the liquid outlet channel, the main channel includes a tapered section and a straight section, wherein the opening width of the tapered section gradually increases from the outside to the inside, so that the polishing liquid quickly enters the main channel through the liquid inlet channel, and then enters the interior of the retaining ring from the liquid outlet channel; d. The first groove is a self-excited fluid oscillator based on the wall effect, which can efficiently transport the polishing liquid on the surface of the polishing pad to the interior of the retaining ring; e. The bottom surface of the first groove has a slope, and the depth of the first groove gradually decreases from the outside to the inside, so that the polishing liquid entering the first groove can be appropriately accelerated toward the inner supply of the retaining ring; f. The first groove may also be inclined, and an angle of 3 to 15° is set between a line connecting the inner port of the liquid outlet channel of the first groove and the center of the retaining ring and the center line of the first groove to promote mixing of the polishing liquid inside the retaining ring so that the abrasive particles in the polishing liquid are in full contact with the surface to be polished of the wafer. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the embodiments of the present application. For ordinary technicians in this field, other drawings can also be obtained based on these drawings.

[0031] Figure 1 is a schematic diagram of a retaining ring provided by an embodiment of the present invention; Figure 2 yes Figure 1 A partial enlarged view of the middle A; Figure 3 It is a schematic diagram of the flow direction of the polishing liquid entering the interior of the retaining ring through the liquid inlet channel provided by one embodiment of the present invention; Figure 4 is a schematic diagram of the flow direction of the polishing liquid in the feedback channel provided by the present invention; Figure 5 is a schematic diagram of a retaining ring for chemical mechanical polishing provided by another embodiment of the present invention; Figure 6 is a schematic diagram of a retaining ring with an inclined first groove provided by an embodiment of the present invention; Figure 7 is a cross-sectional view of a retaining ring provided by one embodiment of the present invention; Figure 8 Schematic diagram of the flow field of the polishing liquid entering and exiting the retaining ring according to one embodiment of the present invention; Fig. 9 It is a schematic diagram of a carrier head for chemical mechanical polishing provided by one embodiment of the present invention. DETAILED DESCRIPTION

[0032] In order to enable those skilled in the art to better understand the technical solutions in the embodiments of the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments in the embodiments of the present application should fall within the scope of protection of the embodiments of the present application.

[0033] The terms used in this application are for the purpose of describing specific embodiments only and are not intended to limit this application. The singular forms of "a", "said" and "the" used in this application and the appended claims are also intended to include plural forms unless the context clearly indicates other meanings. 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 associated listed items.

[0034] 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 the same type of information from each other. For example, without departing from the scope of this application, the first information may also be referred to as the second information, and similarly, the second information may also be referred to as the first information. Thus, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of this application, the meaning of "multiple" is two or more, unless otherwise clearly and specifically defined.

[0035] In the present invention, "Chemical Mechanical Polishing (CMP)" is also called "Chemical Mechanical Planarization (CMP)", and the wafer is also called substrate, and their meanings and actual functions are equivalent.

[0036] Figure 1 is a schematic diagram of a retaining ring 100 provided in one embodiment of the present invention. Specifically, Figure 1 FIG. 1 is a schematic diagram showing the bottom surface of the retaining ring 100 facing upward. The retaining ring 100 is installed at Fig. 9 The bottom of the carrier head 1000 is shown and participates in completing the chemical mechanical polishing of the wafer as a part of the carrier head 1000.

[0037] During chemical mechanical polishing, a polishing liquid composed of submicron or nano abrasives and chemical solutions flows between the wafer and the polishing pad. The polishing liquid is evenly distributed under the transmission of the polishing pad and the action of the rotating centrifugal force to form a liquid film between the wafer and the polishing pad. The chemical components in the liquid react chemically with the wafer, converting insoluble substances into soluble substances. These chemical reactants are then removed from the wafer surface through micromechanical friction of the abrasives, dissolved into the flowing liquid and carried away. That is, the surface material is removed in the alternating process of chemical film formation and mechanical film removal to achieve surface flattening treatment, thereby achieving the purpose of global flattening.

[0038] In the present invention, the retaining ring 100 includes a retaining ring body, and the lower end surface of the retaining ring body is configured with a first groove 10 and a second groove 20, wherein the number of the first grooves 10 is multiple and they are distributed at intervals along the circumference of the retaining ring body, and the second grooves 20 are arranged between adjacent first grooves 10.

[0039] When polishing the wafer, the polishing liquid enters the interior of the retaining ring 100 through the first groove 10 and the second groove 20. The polishing liquid is located between the polishing pad and the wafer to be polished. The abrasive particles and chemical liquid of the polishing liquid act on the surface material of the wafer to remove the material. The used polishing liquid is discharged to the outside of the retaining ring 100 through the second groove 20, and then centrifugally thrown outward by the rotating polishing disk.

[0040] Figure 1 In the illustrated embodiment, the retaining ring 100 is provided with four first grooves 10; the retaining ring 100 may also be provided with other numbers of first grooves 10, such as three, five, six, etc. The first grooves 10 are evenly distributed along the circumference of the retaining ring body, so that the polishing liquid can evenly enter the interior of the rotating carrier head 1000, that is, enter the interior of the retaining ring 100, through the first grooves 10.

[0041] Figure 1 In the embodiment, the second groove 20 has both the function of liquid inlet and liquid discharge. That is, during chemical mechanical polishing, the second groove 20 located on the polishing liquid supply side has the function of liquid inlet, and at the same time, the second groove 20 away from the polishing liquid supply side has the function of liquid discharge. Since the retaining ring 100 rotates around its own axis with the carrier head 1000, the function of the second groove 20 of the retaining ring 100 is dynamically switched.

[0042] Typically, 3 to 5 second grooves 20 are disposed between adjacent first grooves 10 to serve as inlet and outlet channels for the polishing liquid, thereby ensuring the renewal efficiency of the polishing liquid and achieving efficient removal of wafer surface material.

[0043] In the present invention, the number of the first grooves 10 is smaller than the number of the second grooves 20 to balance the efficiency of entry and discharge of the polishing liquid, promote the flow and mixing of the polishing liquid inside the retaining ring 100, and improve the utilization rate of the polishing liquid.

[0044] Typically, the number of second grooves 20 disposed between adjacent first grooves 10 is 3 to 5, and the spacing between adjacent second grooves 20 is the same, so as to ensure that the retaining ring 100 has good polishing liquid supply performance. Figure 1 In the illustrated embodiment, three second grooves 20 are arranged between adjacent first grooves 10 .

[0045] Figure 2 yes Figure 1 In the partial enlarged view at point A, the first groove 10 is extended along the lower end surface of the retaining ring body; the first groove 10 includes a liquid inlet channel 11 and a liquid outlet channel 12; wherein, the liquid inlet channel 11 is a rectangular groove, which extends inward from the outer side wall 100a of the retaining ring body; and the liquid outlet channel 12 is a conical groove, which faces the inner side wall 100b of the retaining ring body and is arranged opposite to the liquid inlet channel 11.

[0046] It should be noted that, in the present invention, "inside", "inner", "outer" and "outer" are relative to the center of the retaining ring 100; toward the center of the retaining ring 100 is the "inside"; away from the center of the retaining ring 100 is the "outer".

[0047] Furthermore, the width L of the liquid inlet channel 11 is 3.1-3.5 mm to ensure the speed and flow rate of the polishing liquid entering the retaining ring 100 through the first groove 10. Usually, the width of the liquid inlet channel 11 is set to be the same as the width of the second groove 20, and the second groove 20 is set to be roughly the same as the structure and size of the traditional retaining ring; such a setting makes the change of the fluid parameters of the polishing liquid entering the retaining ring 100 relatively small, so as to adjust the corresponding control parameters of the carrier head and achieve uniformity of wafer polishing.

[0048] Figure 2 In the embodiment, the width of the liquid outlet channel 12 gradually increases from the outside to the inside, that is, the liquid outlet channel 12 is a tapered opening structure, so that the polishing liquid can quickly diffuse inside the retaining ring 100. Specifically, the angle α formed by the opening of the liquid outlet channel 12 is 80-170°. Preferably, the angle α formed by the opening of the liquid outlet channel 12 is 90-120°, so that the polishing liquid can quickly enter the interior of the retaining ring 100 and achieve efficient diffusion.

[0049] In the present invention, the value of the opening angle α of the liquid outlet channel 12 is related to the polishing process. Specifically, the larger the value of the opening angle α, the more conducive it is to the dispersion of the polishing liquid abrasive particles, so that the abrasive particles inside the retaining ring 100 are more evenly distributed; the smaller the value of the opening angle α, the faster the liquid can flow into the inside of the retaining ring 100, ensuring a larger flow of the polishing liquid between the polishing pad and the wafer, so as to accelerate the removal rate of the wafer surface material.

[0050] Furthermore, the opening size W0 of the liquid outlet channel 12 close to the outer side wall of the retaining ring body is 1.5 times the width of the liquid inlet channel 11. Figure 2 In the figure, W0=1.5L. This arrangement can ensure the efficiency of the polishing liquid entering the retaining ring 100. It should be noted that in the present invention, the opening size W0 of the liquid outlet channel 12 close to the outer wall of the retaining ring body is the opening width of the liquid outlet channel 12, that is, the opening width of the liquid outlet channel 12 is the minimum width of the liquid outlet channel 12 with a tapered mouth structure.

[0051] Furthermore, the first groove 10 also includes a main channel 13 , which is disposed between the liquid inlet channel 11 and the liquid outlet channel 12 . The polishing liquid enters the interior of the retaining ring 100 from the liquid outlet channel 12 via the liquid inlet channel 11 and the main channel 13 .

[0052] The main channel 13 includes a tapered section 13a and a straight section 13b, wherein the tapered section 13a is connected to the liquid inlet channel 11, and the opening width of the tapered section 13a gradually increases from the outside to the inside. That is, the angle formed by the opening of the tapered section 13a is β( Figure 2 As shown), wherein the angle β is 90-120°, and β<α. The specific effect of such a setting will be described in detail in conjunction with the feedback channel 14 mentioned below.

[0053] Furthermore, the straight section 13 b extends inward from the end of the tapered section 13 a , and its width is greater than the opening width W0 of the liquid outlet channel 12 .

[0054] Figure 2 In the embodiment shown, a feedback channel 14 is further provided between the liquid inlet channel 11 and the liquid outlet channel 12. The number of the feedback channels 14 is two, namely, a first feedback channel 14a and a second feedback channel 14b ( Figure 4 As shown), both are connected with the liquid inlet channel 11 and the liquid outlet channel 12, and the feedback channel 14 is symmetrically arranged on both sides of the main channel 13.

[0055] In the present invention, under the effect of the wall adhesion, the destination of the polishing liquid entering the main channel 13 through the liquid inlet channel 11 is as follows: Figure 3 As shown, the entering polishing liquid is roughly divided into two parts: one part of the polishing liquid enters the interior of the retaining ring 100 through the liquid outlet channel 12 , and the other part of the polishing liquid enters the feedback channel 14 .

[0056] Specifically, the polishing liquid entering the main channel 13 randomly adheres to a side wall surface of the main channel 13. Under the action of the main channel 13, part of the polishing liquid on the wall side will enter the feedback channel 14 and form a vortex separation bubble on the other side of the main channel 13. The separation bubble pushes the polishing liquid to the other side wall surface of the main channel 13. At the same time, the polishing liquid enters the interior of the retaining ring 100 from the liquid outlet channel 12. In this way, the polishing liquid can periodically enter the interior of the retaining ring 100 through the liquid outlet channel 12 in a reciprocating cycle.

[0057] Figure 4 In the process, part of the polishing liquid that enters the first feedback channel 14a will enter the main channel 13 again, and then form a vortex separation bubble inside the main channel 13, and the separation bubble will squeeze the polishing liquid in the main channel 13 toward the outlet channel 12 and the second feedback channel 14b, and then transport part of the polishing liquid in the main channel 13 to the inside of the retaining ring 100; the polishing liquid that enters the second feedback channel 14b repeats the above steps, enters the main channel 13 again and forms a vortex separation bubble with a rotation direction opposite to the main channel 13, and then squeezes the polishing liquid in the main channel 13 toward the outlet channel 12 and the first feedback channel 14a. That is, the first groove 10 is a self-excited fluid oscillator (accelerator) based on the wall effect, which can efficiently transport the polishing liquid on the surface of the polishing pad to the inside of the retaining ring 100 in the form of a swinging jet.

[0058] The swing angle of the jet formed by the polishing liquid is 73% of the opening angle α of the liquid outlet channel 12, that is, the swing angles of two adjacent jets account for 73% of the opening angle α of the liquid outlet channel 12. In order to ensure that the polishing liquid entering the retaining ring 100 is fully mixed, the opening angle α of the liquid outlet channel 12 needs to be comprehensively determined according to the number of the first grooves 10. Figure 5 In the embodiment shown, there are three first grooves 10 which are evenly distributed. To ensure even distribution of the polishing liquid, the swing angle of the jet formed by the polishing liquid is at least 120°, and the corresponding opening angle α of the liquid outlet channel 12 is 165°.

[0059] In the present invention, the width W1 of the feedback channel 14 is 1 to 1.5 times the width L of the liquid inlet channel 12 , that is, W1 = 1 to 1.5 L, so as to control the polishing liquid to flow back to the main channel 13 through the feedback channel 14 . Figure 2 In the illustrated embodiment, the width of the feedback channel 14 is 1.2 times the width of the liquid inlet channel 12 , so as to control the flow rate of the polishing liquid flowing back to the main channel 13 through the feedback channel 14 .

[0060] In the present invention, the opening of the tapered section 13a of the main channel 13 forms an angle β, and the opening of the liquid outlet channel 12 forms an angle α, wherein β<α. In this arrangement, the polishing liquid flows forward along the randomly attached sidewall, and is partially blocked at the inner end surface of the liquid outlet channel 12, so that part of the polishing liquid flows back to the inside of the feedback channel 14, thereby forming a significant wall attachment effect, so that the first groove 10 forms a self-excited vibrator without the need for an additional power source, so as to periodically transport the polishing liquid to the inside of the retaining ring 100.

[0061] Figure 1 In the embodiment shown, the first groove 10 is a symmetrical structure, and its symmetry axis ( Figure 2 The dot-dash line) passes through the center of the retaining ring 100 so that the polishing liquid can flow to the center of the retaining ring 100, so that the rotating retaining ring 100 can fully mix the fluid inside the retaining ring 100.

[0062] Furthermore, the width W of the first trench 10 ( Figure 2 As shown) is 0.8 times the radial dimension of the retaining ring body, that is, the width W of the first groove is 0.8 times the radial dimension of the retaining ring 100, so as to form a main channel 13 and a feedback channel 14 on the lower end face of the retaining ring body, and then under the action of the wall attachment effect, the polishing liquid can periodically enter the interior of the retaining ring 100 through the liquid outlet channel 12.

[0063] Figure 1 In the illustrated embodiment, the second groove 20 is a straight groove, the center line of which points to the center of the retaining ring 100, that is, the center of the retaining ring 100 is on the center line of the second groove 20, so as to facilitate the entry and discharge of the polishing liquid.

[0064] It is understandable that the second groove 20 may also be an oblique groove. Figure 1 As for the straight grooves shown, both are rectangular grooves, while the center line of the oblique groove does not point to the center of the retaining ring 100, and is deflected to a certain extent relative to the center of the retaining ring 100.

[0065] Figure 5 It is a schematic diagram of a retaining ring 100 for chemical mechanical polishing provided by another embodiment of the present invention. In this embodiment, the number of first grooves 10 is 3, the number of second grooves 20 between adjacent first grooves 10 is 4, and the second grooves 20 are oblique grooves.

[0066] The angle between the line connecting the inner end of the second groove 20 and the center of the retaining ring and the center line of the second groove 20 is θ. Figure 5 As shown, the angle θ is 45-60°. It can be understood that the angle θ can be within the range of 45-60°.

[0067] It should be noted that the inclination direction of the second groove 20 is related to the rotation direction of the polishing disk and the carrier head of the CMP system. The inclination direction of the second groove 20 needs to conform to the rotation direction of the polishing disk and the carrier head to facilitate the polishing liquid to enter and flow out of the retaining ring 100 through the second groove 20.

[0068] In the present invention, the first groove 10 may also be arranged obliquely, such as Figure 6 As shown, the angle between the line between the inner port of the liquid outlet channel of the first groove 10 and the center of the retaining ring 100 and the center line of the first groove 10 is δ, and the angle δ is 3~15°, so as to promote the mixing of the polishing liquid inside the retaining ring 100, so that the abrasive particles in the polishing liquid are in full contact with the surface to be polished of the wafer.

[0069] Figure 6 In the illustrated embodiment, the second groove 20 configured in the retaining ring 100 is a straight groove, that is, the center line of the second groove 20 passes through the center of the circle of the retaining ring 100. It is understandable that the retaining ring 100 with the first groove 10 arranged obliquely can also be provided with the second groove 20 of the oblique groove. In order to avoid the collision of the polishing liquid during the supply process and cause the energy loss of the fluid, the inclination direction of the first groove 10 and the second groove 20 needs to be consistent. That is, if the first groove 10 is inclined counterclockwise, the second groove 20 is also inclined counterclockwise.

[0070] In the present invention, the depth of the first groove 10 is greater than or equal to the depth of the second groove 20 to regulate the efficiency of the polishing liquid entering and exiting the retaining ring 100, balance the usage rate of the polishing liquid, and control the wafer manufacturing cost.

[0071] Specifically, when the depth of the first groove 10 is greater than the depth of the second groove 20, the efficiency of the polishing liquid entering the retaining ring 100 can be improved, while the efficiency of the polishing liquid exiting the retaining ring 100 can be appropriately reduced to improve the utilization rate of the polishing liquid. It should be noted that the depth of the first groove 10 is slightly greater than the depth of the second groove 20.

[0072] Preferably, the depth of the first groove 10 is 3.5-4.5 mm to form a vortex separation bubble inside the first groove 10 , and then the first groove 10 forms a self-excited vibrator based on the wall effect to passively and efficiently supply the polishing liquid to the inside of the retaining ring 100 .

[0073] Figure 7 1 is a cross-sectional view of a retaining ring 100 provided in an embodiment of the present invention, wherein the cross-sectional plane passes through the symmetry axis of the first groove 10. In this embodiment, the bottom surface of the first groove 10 has a slope, and the depth of the first groove 10 gradually decreases from the outside to the inside, so that the polishing liquid entering the first groove 10 can be appropriately accelerated to be supplied toward the inside of the retaining ring 100.

[0074] Furthermore, the difference between the depth of the first groove 10 at the outer side wall 100a and the depth at the inner side wall 100b is 0.5-1 mm. Preferably, the difference between the depth of the first groove 10 at the outer side wall 100a and the depth at the inner side wall 100b is 0.8 mm. The outer side depth of the first groove 10 is larger, and this part can store more polishing liquid, which is conducive to reducing the resistance encountered by the polishing liquid when entering the retaining ring 100, and the depth of the first groove 10 gradually becomes shallower from the outside to the inside; the pressure in the first groove 10 gradually increases from the outside to the inside, and the cross-sectional area of ​​the first groove 10 corresponding to the inner side wall 100b of the retaining ring 100 becomes smaller, which allows the polishing liquid to enter the interior of the retaining ring 100 at an accelerated speed.

[0075] Figure 8 It is a schematic diagram of the flow field of the polishing liquid entering and discharging the retaining ring provided by an embodiment of the present invention. The polishing liquid enters the retaining ring 100 through the first groove 10 and the second groove 20 on the polishing liquid supply side, and is then discharged through the second groove 20 away from the polishing liquid supply side. Figure 8 In the figure, dotted lines are used to indicate that the polishing liquid flows toward the inside of the retaining ring 100, and solid lines are used to indicate that the polishing liquid flows outside the retaining ring 100.

[0076] It should be noted that the polishing liquid entering the retaining ring 100 will flow and mix inside the retaining ring 100 under the interaction of the rotating polishing pad and the wafer, so that the abrasive particles of the polishing liquid are in full contact with the wafer, thereby improving the utilization rate of the polishing liquid.

[0077] In addition, the present invention also provides a carrier head 1000 for chemical mechanical polishing, a schematic diagram of which is shown in FIG. Fig. 9 As shown, the carrier head 1000 includes: Coupling plate 200; The carrier plate 300 is disposed below the coupling plate 200; The elastic membrane 400 is disposed below the carrier plate 300; like Figure 1 The retaining ring 100 is shown, and the retaining ring 100 is disposed below the carrier plate 300 and located on the outer peripheral side of the elastic membrane 400 .

[0078] Specifically, the coupling disk 200 is a disk-shaped structure, which is connected to the supporting disk 300 through an annular membrane, and a through hole is arranged in the middle of the coupling disk 200; the supporting disk 300 is a disk-shaped structure, and a balance frame 500 is arranged between it and the coupling disk 200; specifically, the balance frame 500 is coaxially arranged with the coupling disk 200; the elastic membrane 400 is connected to the bottom of the supporting disk 300, and the retaining ring 100 is detachably connected to the outer peripheral side of the elastic membrane 400.

[0079] Furthermore, the balance frame 500 includes a central axis portion, a chassis portion, a peripheral wall portion, and a flange portion. The central axis portion can be slidably inserted into the through hole of the coupling plate 200 and can move therein in a vertical direction, and the flange portion of the balance frame 500 is coupled to the central stepped hole of the carrier plate 300 by means of a washer, a clamp ring, and bolts (not shown), so that the carrier plate 300 can rotate and / or move in a vertical direction together with the balance frame 500.

[0080] The top of the coupling disc 200 is provided with a connection flange (not shown), which is connected to an external drive shaft. The rotating coupling disc 200 drives the carrier disc 300 and the elastic membrane 400 thereon to rotate coaxially via the annular membrane. The elastic membrane 400 loaded with the wafer is pressed against the rotating polishing pad, and the polishing liquid is supplied between the wafer and the polishing pad. Under the action of chemistry and mechanics, the material on the bottom surface of the wafer is removed.

[0081] In the present invention, the carrier head 1000 is configured with Figure 1 The retaining ring 100 shown, due to the wall attachment effect, the first groove 10 on the lower end surface of the retaining ring 100 forms a self-excited vibrator, so that the polishing liquid can periodically enter the interior of the retaining ring 100. The operation of the retaining ring 100 does not require additional excitation or power source, which effectively improves the utilization rate of the polishing liquid and is beneficial to controlling the manufacturing cost of the wafer.

[0082] Those of ordinary skill in the art will appreciate that the units and method steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of the embodiments of the present application.

[0083] The above implementation methods are only used to illustrate the embodiments of the present application, and are not limitations on the embodiments of the present application. Ordinary technicians in the relevant technical field can make various changes and modifications without departing from the spirit and scope of the embodiments of the present application. Therefore, all equivalent technical solutions also belong to the scope of the embodiments of the present application. The scope of patent protection of the embodiments of the present application should be limited by the claims.

Claims

1. A retaining ring for chemical mechanical polishing, characterized in that: It comprises a retaining ring body, wherein the lower end surface of the retaining ring body is provided with a first groove and a second groove, wherein the first grooves are multiple and spaced apart, and the second grooves are arranged between adjacent first grooves; The polishing liquid used in chemical mechanical polishing enters the interior of the retaining ring through the first groove and the second groove, and the used polishing liquid is discharged to the outside of the retaining ring through the second groove.

2. The retaining ring according to claim 1, characterized in that: The number of the first grooves is smaller than the number of the second grooves.

3. The retaining ring according to claim 2, characterized in that: The number of the second grooves arranged between adjacent first grooves is 3 to 8.

4. The retaining ring according to claim 1, characterized in that: The first groove is extended along the lower end surface of the retaining ring body, and includes a liquid inlet channel and a liquid outlet channel; the liquid inlet channel is a rectangular groove, which extends from the outer wall of the retaining ring body toward the inside; the liquid outlet channel is a conical groove, which faces the inner wall of the retaining ring body and is opposite to the liquid inlet channel.

5. The retaining ring according to claim 4, characterized in that: The width of the liquid outlet channel gradually increases from the outside to the inside.

6. The retaining ring according to claim 4, characterized in that: The opening of the liquid outlet channel forms an angle of 80-170°.

7. The retaining ring according to claim 4, characterized in that: A main channel is arranged between the liquid inlet channel and the liquid outlet channel, and includes a tapered section and a straight section; the tapered section is connected to the liquid inlet channel, and its width gradually increases from the outside to the inside; the straight section extends inward from the tapered section, and its width is greater than the opening width of the liquid outlet channel.

8. The retaining ring according to claim 7, characterized in that A feedback channel is also arranged between the liquid inlet channel and the liquid outlet channel, and the number of the feedback channels is two and they are symmetrically arranged on both sides of the main channel.

9. The retaining ring according to claim 8, characterized in that The feedback channel, the main channel, the liquid inlet channel and the liquid outlet channel are interconnected, and the width of the feedback channel is 1 to 1.5 times the width of the liquid inlet channel.

10. The retaining ring according to claim 4, characterized in that The width of the liquid inlet channel is 3.1-3.5 mm.

11. The retaining ring according to claim 4, characterized in that The opening size of the liquid outlet channel close to the outer side wall of the retaining ring body is 1.5 times that of the liquid inlet channel.

12. The retaining ring according to claim 1, characterized in that The first groove is a symmetrical structure, and its symmetry axis passes through the center of the retaining ring.

13. The retaining ring according to claim 12, characterized in that The width of the first groove is 0.8 times the radial dimension of the retaining ring body.

14. The retaining ring according to claim 1, characterized in that The second groove is a straight groove, and the central axis thereof points to the center of the retaining ring.

15. The retaining ring according to claim 1, characterized in that The second groove is an oblique groove, and the angle between the line between the inner port and the center of the retaining ring and the central axis of the second groove is 45-60 degrees.

16. The retaining ring according to claim 4, characterized in that The first groove is inclined, and the angle between the line between the inner port of the liquid outlet channel and the center of the retaining ring and the central axis of the first groove is 3-15°.

17. The retaining ring according to claim 4, characterized in that The width of the liquid inlet channel is equal to the width of the second groove.

18. The retaining ring according to claim 1, characterized in that The depth of the first groove is greater than or equal to the depth of the second groove.

19. The retaining ring according to claim 1, characterized in that The depth of the first groove is 3.5-4.5 mm.

20. The retaining ring according to claim 1, characterized in that The bottom surface of the first groove has a slope, and the depth of the first groove gradually decreases from the outside to the inside.

21. The retaining ring according to claim 20, characterized in that The difference between the depth of the first groove on the outer side wall and the depth of the first groove on the inner side wall is 0.5-1 mm.

22. A carrier head for chemical mechanical polishing, characterized in that: include: Coupling plate; A bearing plate, arranged below the coupling plate; An elastic membrane, disposed below the carrying plate; The retaining ring according to any one of claims 1 to 21 is arranged below the carrier plate and located on the outer peripheral side of the elastic membrane.

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