Bearing head for chemical mechanical polishing and chemical mechanical polishing system

Abstract

The invention discloses a bearing head for chemical mechanical polishing and a chemical mechanical polishing system, and relates to the technical field of semiconductor manufacturing. The bearing disc is arranged below the coupling disc; the elastic film is arranged below the bearing disc; the retaining ring is arranged below the bearing disc and located on the peripheral side of the elastic film, the retaining ring comprises a retaining ring body, the lower end face of the retaining ring body is provided with a plurality of first grooves and second grooves, the first grooves are distributed at intervals, and the second grooves are formed between the adjacent first grooves; a polishing solution used for chemical mechanical polishing enters the retaining ring through the first groove and the second groove, and the used polishing solution is discharged to the outer side of the retaining ring through the second groove; the first groove extends along the lower end face of the retaining ring body and comprises a liquid inlet hole channel and a liquid outlet hole channel. And the liquid inlet hole channel extends towards the inner side from the outer side wall of the retaining ring main body.

Description

Technical Field

[0001] The embodiments of the present application relate to the field of semiconductor manufacturing technology, and in particular to a carrier head and a chemical mechanical polishing system 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 design of the groove at the bottom of the retaining ring is very important. If the width of the groove is set too small, it will affect the speed and amount of the polishing liquid entering, and thus affect the removal rate of the wafer surface; if the width of the groove is set too large, the polishing liquid will hardly stay inside the carrier head, that is, the polishing liquid will enter through one side of the carrier head and then flow out from the other side of the carrier head, and will hardly participate in chemical mechanical polishing, resulting in a reduced utilization rate of the polishing liquid.

[0006] However, as the wafer polishing process advances, simply adjusting the width of the groove of the retaining ring cannot meet the requirements of polishing efficiency, polishing accuracy and polishing cost control. Summary of the invention

[0007] In view of this, embodiments of the present application provide a carrier head and a chemical mechanical polishing system for chemical mechanical polishing to at least partially solve the above problems.

[0008] According to a first aspect of an embodiment of the present application, there is provided a carrier head for chemical mechanical polishing, comprising:

[0009] Coupling plate;

[0010] A bearing plate, arranged below the coupling plate;

[0011] An elastic membrane, disposed below the carrying plate;

[0012] A retaining ring is arranged below the carrier plate and located on the outer peripheral side of the elastic membrane, and comprises a retaining ring body, wherein the lower end face 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; the first groove is extended along the lower end face of the retaining ring body, and comprises a liquid inlet channel and a liquid outlet channel; the liquid inlet channel is a rectangular groove, which extends from the outer side wall of the retaining ring body toward the inside; the liquid outlet channel is a conical groove, which faces the inner side wall of the retaining ring body and is arranged opposite to the liquid inlet channel; the width of the liquid outlet channel gradually increases from the outside to the inside, and the opening of the liquid outlet channel forms an angle of 80 to 170°.

[0013] In some embodiments, the first groove is a self-excited fluid oscillator based on the Coanda effect, which delivers the polishing liquid to the interior of the retaining ring.

[0014] 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.

[0015] In some embodiments, a feedback channel is further provided between the liquid inlet channel and the liquid outlet channel, and two feedback channels are provided symmetrically on both sides of the main channel; 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 1.5 times the width of the liquid inlet channel.

[0016] 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.

[0017] In some embodiments, the first groove is arranged obliquely, 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 to 15 degrees.

[0018] In some embodiments, the second groove is inclined, and its longitudinal section is a rectangular groove, and the angle between the line between the inner port of the second groove and the center of the retaining ring and the central axis of the second groove is 45-60°.

[0019] In some embodiments, the number of the first grooves is 3-5, and the number of the second grooves between adjacent first grooves is 3-5.

[0020] In some embodiments, the retaining ring body is a stacked structure, which includes an upper structure and a lower structure, which are clamped and fixed, and the first groove and the second groove are arranged on the lower structure; a plurality of upper protrusions are arranged below the upper structure, and a plurality of lower recesses are arranged matchingly on the lower structure; the setting positions of the first groove and the second groove are staggered circumferentially with the recesses.

[0021] In some embodiments, the retaining ring body is an annular through-body structure, which includes an inner layer structure and an outer layer structure, the outer layer structure is coated on the outer side of the inner layer structure, the first groove and the second groove are arranged on the outer layer structure of the outer layer; a plurality of inner layer protrusions are arranged below the inner layer structure, and a plurality of outer layer recesses are arranged matchingly on the outer layer structure; the setting positions of the first groove and the second groove are circumferentially staggered with the outer layer recesses.

[0022] According to the second aspect of an embodiment of the present application, a chemical mechanical polishing system is provided, which includes a polishing disk, a liquid supply device, a trimming device and the carrying head described above, wherein the carrying head presses the wafer to be polished against the polishing pad above the polishing disk, the liquid supply device supplies polishing liquid toward between the polishing pad and the wafer, and the trimming device is used to trim the surface of the polishing pad.

[0023] The beneficial effects of the present invention include:

[0024] a. The holding ring of the carrier head has a first groove and a second groove, wherein the first groove is only used for supplying the polishing liquid, and the second groove has the function of supplying and discharging the polishing liquid, which is conducive to regulating the time of the polishing liquid inside the holding ring and improving the use efficiency of the polishing liquid;

[0025] b. The number of the first grooves is smaller 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;

[0026] c. 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, so that the polishing liquid can quickly diffuse inside the retaining ring;

[0027] 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 inside of the retaining ring;

[0028] 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 to be supplied toward the inside of the retaining ring;

[0029] f. The main body of the retaining ring is a stacked structure, which includes an upper structure and a lower structure, which are fixed by clamping, and the first groove and the second groove are arranged on the lower structure; a plurality of upper convex parts are arranged below the upper structure, and a plurality of lower concave parts are arranged on the lower structure to match; the arrangement positions of the first groove and the second groove are staggered in the circumferential direction with the lower concave parts to balance the rigidity and strength of the lower structure, while taking into account the control of the bottom surface shape of the retaining ring;

[0030] g. The retaining ring body is an annular through-body structure, which includes an inner layer structure and an outer layer structure, wherein the outer layer structure is coated on the outer side of the inner layer structure, and the first groove and the second groove are arranged on the outer layer structure; a plurality of inner layer protrusions are arranged below the inner layer structure, and a plurality of outer layer concave portions are arranged matchingly on the outer layer structure; the arrangement positions of the first groove and the second groove are staggered circumferentially with the outer layer concave portions to balance the stiffness and strength of the outer layer structure while taking into account the control of the bottom surface shape of the retaining ring. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] 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.

[0032] Figure 1 is a schematic diagram of a carrier head for chemical mechanical polishing provided by an embodiment of the present invention;

[0033] Figure 2 yes Figure 1 is a bottom view of the retaining ring shown;

[0034] Figure 3 yes Figure 2 A partial enlarged view of the middle A;

[0035] Figure 4 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;

[0036] Figure 5 is a schematic diagram of the flow direction of the polishing liquid in the feedback channel provided by the present invention;

[0037] Figure 6 is a schematic diagram of a retaining ring provided by another embodiment of the present invention;

[0038] Figure 7 is a cross-sectional view of a retaining ring provided by one embodiment of the present invention;

[0039] Figure 8 is a schematic diagram of a stacked retaining ring provided by an embodiment of the present invention;

[0040] Fig. 9 is a schematic diagram of a wrapped retaining ring provided by an embodiment of the present invention;

[0041] Fig.10 is a cross-sectional view of a retaining ring provided by another embodiment of the present invention;

[0042] Fig.11 Schematic diagram of a chemical mechanical polishing system provided by one embodiment of the present invention. DETAILED DESCRIPTION

[0043] 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.

[0044] 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.

[0045] 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.

[0046] 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.

[0047] 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.

[0048] Figure 1 is a schematic diagram of a carrier head 1000 for chemical mechanical polishing provided by an embodiment of the present invention. In this embodiment, the carrier head 1000 includes:

[0049] Coupling plate 200;

[0050] The carrier plate 300 is disposed below the coupling plate 200;

[0051] The elastic membrane 400 is disposed below the carrier plate 300;

[0052] The retaining ring 100 is disposed below the carrier plate 300 and located on the outer peripheral side of the elastic membrane 400 .

[0053] 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.

[0054] Figure 1 In the embodiment, 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 the central axis portion of the balance frame 500 can move in the vertical direction in the through hole, and the flange portion of the balance frame 500 is connected 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 the vertical direction together with the balance frame 500.

[0055] 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, chemical mechanical polishing is performed to achieve material removal from the bottom surface of the wafer.

[0056] Figure 2 yes Figure 1 1 is an overhead view of a retaining ring 100, wherein the retaining ring 100 includes a retaining ring body, and a first groove 10 and a second groove 20 are arranged on the lower end surface of the retaining ring body, wherein there are a plurality of first grooves 10 which are spaced apart circumferentially along the retaining ring body to supply polishing liquid toward the interior of the retaining ring 100, and the second grooves 20 are arranged between adjacent first grooves 10, and one of their functions is to discharge the used polishing liquid toward the outside of the retaining ring 100.

[0057] 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.

[0058] Figure 2 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, 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, so that the polishing liquid contacts the bottom surface of the wafer inside the retaining ring 100.

[0059] Figure 2 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.

[0060] 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.

[0061] 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.

[0062] Usually, the number of the second grooves 20 arranged between adjacent first grooves 10 is 3 to 5, and the intervals between adjacent second grooves 20 are the same, so as to ensure that the retaining ring 100 has good polishing liquid supply performance. Figure 2 In the illustrated embodiment, three second grooves 20 are arranged between adjacent first grooves 10 .

[0063] Figure 3 yes Figure 2 In the partial enlarged view at point A, in order to reflect the concavo-convexity of the lower end surface of the retaining ring 100, the protruding part of the lower end surface is shown with a section line, so as to clearly show the structure of the first groove 10.

[0064] Specifically, the first groove 10 is extended roughly along the radial direction of the retaining ring 100 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 wall 100a of the retaining ring body; and the liquid outlet channel 12 is a conical groove, which is arranged toward the inner wall 100b of the retaining ring body, and the liquid outlet channel 12 is opposite to the setting position of the liquid inlet channel 11.

[0065] 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".

[0066] 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 1000 and achieve uniformity of wafer polishing.

[0067] Figure 3In 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 toward the inside of the retaining ring 100. Specifically, the angle α formed by the opening of the liquid outlet channel 12 is 80 to 170°. Preferably, the angle α formed by the opening of the liquid outlet channel 12 is 90 to 120°, so that the polishing liquid can quickly enter the inside of the retaining ring 100 and achieve efficient diffusion.

[0068] 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, which is conducive to a more uniform distribution of the abrasive particles inside the retaining ring 100; the smaller the value of the opening angle α, the faster the polishing liquid can flow into the inside of the retaining ring 100, ensuring the flow of the polishing liquid between the polishing pad and the wafer, thereby accelerating the removal rate of the wafer surface material.

[0069] Furthermore, the opening size W0 of the liquid outlet channel 12 close to the outer wall of the retaining ring body is 1.5 times the width of the liquid inlet channel 11. That is, 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.

[0070] 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 .

[0071] 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 3 As shown), wherein the included 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.

[0072] 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 .

[0073] Figure 3 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 5As 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.

[0074] 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 roughly divided into two parts ( Figure 4 ): a portion of the polishing liquid enters the interior of the retaining ring 100 through the liquid outlet channel 12 , and a portion of the polishing liquid enters the feedback channel 14 .

[0075] 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, the polishing liquid on the side of the wall will partially 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. That is, the first groove 10 forms a self-excited fluid oscillator based on the wall effect to transport the polishing liquid to the interior of the retaining ring 100.

[0076] Figure 5 In the process, part of the polishing liquid entering 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 entering 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. That is, the first groove 10 is a self-excited fluid oscillator based on the wall effect, which transports the polishing liquid to the inside of the retaining ring 100.

[0077] 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 angle of two adjacent jets accounts 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, it is necessary to comprehensively determine the opening angle α of the liquid outlet channel 12 according to the number of first grooves 10. In some embodiments, if the number of first grooves 10 is 3 and evenly distributed; in order to ensure that the polishing liquid is evenly distributed, 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°.

[0078] 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 1.5L, so as to control the polishing liquid to flow back to the main channel 13 through the feedback channel 14 . Figure 3 In the illustrated embodiment, the width of the feedback channel 14 is 1.2 times the width of the liquid inlet channel 12 to control the flow rate of the polishing liquid flowing back to the main channel 13 through the feedback channel 14 .

[0079] 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. With such a configuration, the polishing liquid can flow forward along the randomly attached sidewalls, and it will be 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, which periodically delivers the polishing liquid to the inside of the retaining ring 100 without the need for an additional power source.

[0080] Figure 6 1 is a schematic diagram of a retaining ring 100 provided by another embodiment of the present invention, wherein the first groove 10 is arranged at an angle. That is, there is an angle δ between the line connecting the inner end of the liquid outlet channel 12 and the center of the retaining ring 100 and the central axis of the first groove 10, rather than Figure 2 The two lines in the embodiment coincide with each other. The central axis of the first groove 10 is the central line of the liquid inlet channel 11 .

[0081] In some embodiments, the angle δ between the line between the inner port of the liquid outlet channel 12 and the center of the retaining ring 100 and the central axis of the first groove 10 is 3 to 15°, and the deflection direction of the first groove 10 is consistent with the diffusion direction of the polishing liquid inside the retaining ring 100, so as to accelerate the efficient diffusion of the polishing liquid and improve the uniformity of the distribution of the polishing liquid inside the retaining ring 100.

[0082] During chemical mechanical polishing, the rotation direction of the polishing disk is consistent with that of the carrier head, and the polishing liquid is distributed above the polishing pad that rotates synchronously with the polishing disk. Therefore, the inclined direction of the first groove 10 is related to the rotation direction of the carrier head.

[0083] Figure 6 The second groove 20 is also inclined, and its longitudinal section is a rectangular groove to ensure the fluidity of the polishing liquid. The angle between the line between the inner port of the second groove 20 and the center of the retaining ring 100 and the central axis of the second groove 20 is θ, and the angle θ is 45-60°.

[0084] In the present invention, the retaining ring body may be a stacked structure, which includes an upper structure 100s and a lower structure 100u, such as Figure 7As shown in Figure (a), the two are fixedly connected, wherein the first groove 10 and the second groove 20 are provided in the lower structure 100u. Usually, the upper structure 100s is made of metal material with good rigidity, while the lower structure 100u is made of non-metal material with strong wear resistance, such as PPS, PEEK and the like.

[0085] Figure 8 An embodiment of the present invention provides Figure 7 (a) is a schematic diagram of the retaining ring 100. In this embodiment, a plurality of upper protrusions 100s-1 are arranged below the upper structure 100s, and a plurality of lower recesses 100u-1 are arranged to match the lower structure 100u; specifically, the shape and size of the upper protrusions 100s-1 are matched with the shape and size of the lower recesses 100u-1, so that the upper structure 100s is snap-fitted to the lower structure 100u.

[0086] In the present invention, the first groove 10 and the second groove 20 are arranged at positions that are circumferentially staggered with the lower recess 100u-1, so that the groove structures on the top and bottom surfaces of the lower structure 100u are roughly evenly distributed, so as to ensure the overall strength of the lower structure 100u, and at the same time, it is conducive to forming an inclined surface that meets the process requirements on the bottom surface of the lower structure 100u. This is because the groove structure is roughly evenly distributed, which is conducive to controlling the deformation of the lower structure 100u along the radial direction, thereby obtaining a micron-level inclined surface; the micron-level inclined surface is conducive to shortening the running-in time of the retaining ring 100, thereby controlling the cost of wafer manufacturing. At the same time, the setting of the inclined surface on the bottom surface of the retaining ring 100 is conducive to the retaining ring 100 participating in the control of the polishing pressure of the carrier head 1000, that is, the retaining ring 100 is combined with the elastic membrane 400 to accurately control the rate of material removal, thereby obtaining a wafer with global flattening accuracy that meets the requirements.

[0087] In some embodiments, the retaining ring body may also be an annular through-body structure, which includes an inner layer structure 100i and an outer layer structure 100e, such as Figure 7 As shown in Figure (b), the outer layer structure 100e is coated on the outer side of the inner layer structure 100i, wherein the first groove 10 and the second groove 20 are arranged on the bottom surface of the outer layer structure 100e. Usually, the outer layer structure 100e is made of non-metallic materials with good wear resistance, and the inner layer structure 100i can be made of metal and / or non-metallic materials to ensure the rigidity of the retaining ring 100. Since the encapsulated retaining ring 100 has no metal leakage, it is beneficial to suppress the influence of metal on the detection accuracy of the film thickness measurement module.

[0088] As one aspect of this embodiment, a plurality of inner layer protrusions 100i-1 are provided below the inner layer structure 100i. Fig. 9As shown, the outer layer structure 100e is matched with a plurality of outer layer recesses 100e-1; specifically, the shape and size of the inner layer protrusion 100i-1 are matched with the shape and size of the outer layer recess 100e-1 to ensure that the two are snap-fitted and fixed as one.

[0089] Understandably, Fig. 9 In the embodiment shown, the outer layer structure 100e partially covers the outer side of the inner layer structure 100i, that is, except for the top surface of the inner layer structure 100i, its side surface and bottom surface are covered inside the outer layer structure 100e. If the inner layer structure 100i is made of metal material, the metal material can also be exposed by means of the carrier plate 300.

[0090] Furthermore, the arrangement positions of the first groove 10 and the second groove 20 are circumferentially staggered with the outer layer recess 100e-1, so that the groove structures are dispersedly arranged in the outer layer structure 100e, which is conducive to ensuring the overall rigidity of the retaining ring 100. At the same time, such an arrangement makes the groove structures of the outer layer structure 100e evenly distributed, which is conducive to controlling the deformation of the outer layer structure 100e along the radial direction, so as to form a micron-level inclined surface on the bottom surface of the outer layer structure 100e, so as to shorten the running-in time of the retaining ring 100, so that the retaining ring 100 participates in the polishing pressure control of the carrier head 1000, and improves the uniformity of wafer polishing.

[0091] Fig.10 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.

[0092] 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 to 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.

[0093] In addition, an embodiment of the present invention further provides a chemical mechanical polishing system, Fig.11Schematic diagram of the chemical mechanical polishing system of the present invention. The chemical mechanical polishing system comprises a polishing plate 3000, a polishing pad 2000, a dressing device 4000, a liquid supply device 5000 and the carrier head 1000 described above.

[0094] Among them, the polishing pad 2000 is arranged on the upper surface of the polishing disk 3000 and rotates therewith along the axis Ax; the horizontally movable carrying head 1000 is arranged above the polishing pad 2000, and its lower surface receives the wafer to be polished; the dressing device 4000 includes a dressing arm and a dressing head, which is arranged on one side of the polishing disk 3000, and the dressing arm drives the rotating dressing head to swing to dress the surface of the polishing pad 2000; the liquid supply device 5000 is arranged on the upper side of the polishing pad 2000 to spread the polishing liquid on the surface of the polishing pad 2000.

[0095] During the polishing operation, the carrier head 1000 presses the surface of the wafer to be polished against the surface of the polishing pad 2000, and the carrier head 1000 rotates and reciprocates along the radial direction of the polishing disk 3000 so that the surface of the wafer in contact with the polishing pad 2000 is gradually polished; at the same time, the polishing disk 3000 rotates, and the liquid supply device 5000 sprays the polishing liquid onto the surface of the polishing pad 2000. Under the chemical action of the polishing liquid, the relative movement of the carrier head 1000 and the polishing disk 3000 causes the wafer to rub against the polishing pad 2000 for polishing.

[0096] During chemical mechanical polishing, the dressing device 4000 is used to dress and activate the surface morphology of the polishing pad 2000. The dressing device 4000 can remove foreign particles remaining on the surface of the polishing pad, such as abrasive particles in the polishing liquid and waste materials falling off the wafer surface, and can also flatten the surface deformation of the polishing pad 2000 caused by grinding, thereby ensuring the consistency of the surface morphology of the polishing pad 2000 during polishing, thereby maintaining a stable polishing removal rate.

[0097] Fig.11 The carrier head 1000 is configured with Figure 2 or Figure 6 The retaining ring 100 is shown, and the lower end surface of the retaining ring 100 is configured with a first groove 10 and a second groove 20. 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.

[0098] In summary, the retaining ring 100 of the carrier head 1000 provided by the present invention does not need to adapt to the polishing process by simply changing the width of the retaining ring groove, which effectively improves the application scope and flexibility of the carrier head 1000, thereby improving the performance of the carrier head 1000 and even the entire chemical mechanical polishing system.

[0099] 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.

[0100] 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 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; A retaining ring is disposed below the carrier plate and on the outer peripheral side of the elastic membrane, and 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 provided between adjacent first grooves; The polishing liquid used for 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; 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 side wall of the retaining ring body toward the inside; the liquid outlet channel is a conical groove, which faces the inner side wall of the retaining ring body and is arranged opposite to the liquid inlet channel; the width of the liquid outlet channel gradually increases from the outside to the inside, and the opening of the liquid outlet channel forms an angle of 80 to 170°.

2. The carrier head according to claim 1, characterized in that: The first groove is a self-excited fluid oscillator based on the Coanda effect, which delivers the polishing liquid to the interior of the retaining ring.

3. The carrier head according to claim 2, 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.

4. The carrier head according to claim 3, characterized in that: A feedback channel is also provided between the liquid inlet channel and the liquid outlet channel, and there are two feedback channels, which are symmetrically arranged on both sides of the main channel; 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 1.5 times the width of the liquid inlet channel.

5. The carrier head according to claim 2, 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.

6. The carrier head according to claim 2, characterized in that: The first groove is arranged obliquely, and the angle between the line connecting 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°.

7. The carrier head according to claim 6, characterized in that: The second groove is inclined, and its longitudinal section is a rectangular groove. The angle between the line between the inner port of the second groove and the center of the retaining ring and the central axis of the second groove is 45-60 degrees.

8. The carrier head according to claim 1, characterized in that: The number of the first grooves is 3-5, and the number of the second grooves between adjacent first grooves is 3-5.

9. The carrier head according to claim 1, characterized in that: The retaining ring body is a stacked structure, which includes an upper structure and a lower structure, which are clamped and fixed, and the first groove and the second groove are arranged on the lower structure; a plurality of upper protrusions are arranged below the upper structure, and a plurality of lower recesses are arranged on the lower structure to match; the setting positions of the first groove and the second groove are circumferentially staggered with the lower recesses.

10. The carrier head according to claim 1, characterized in that: The retaining ring body is an annular through-body structure, which includes an inner layer structure and an outer layer structure, the outer layer structure is coated on the outer side of the inner layer structure, the first groove and the second groove are arranged on the outer layer structure; a plurality of inner layer protrusions are arranged below the inner layer structure, and a plurality of outer layer recesses are arranged matchingly on the outer layer structure; the setting positions of the first groove and the second groove are circumferentially staggered with the outer layer recesses.

11. A chemical mechanical polishing system, characterized in that: It comprises a polishing disc, a liquid supply device, a trimming device and a carrier head as described in any one of claims 1 to 10, wherein the carrier head presses the wafer to be polished against the polishing pad above the polishing disc, the liquid supply device supplies polishing liquid toward between the polishing pad and the wafer, and the trimming device is used to trim the surface of the polishing pad.

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