Wafer grinding device and grinding method

Abstract

The invention discloses a wafer grinding device and a grinding method. The wafer grinding device comprises a grinding head unit used for keeping and rotating a wafer; the polishing plate unit is arranged opposite to the grinding head unit, and a grinding pad is arranged on the surface, opposite to the grinding head unit, of the polishing plate unit; wherein the grinding pad is made of a porous material, and a plurality of through holes are formed in the thickness direction of the grinding pad; the polishing plate unit further comprises a suction mechanism arranged below the grinding pad, and the suction mechanism is configured to penetrate through the grinding pad through the through hole to suck and remove by-products generated in the grinding process of the wafer from the grinding area. According to the wafer grinding device, a clean grinding environment can be continuously kept, the stable and efficient grinding rate is achieved, and meanwhile the surface quality of a ground object is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to a chemical mechanical polishing (CMP) device and a chemical mechanical polishing method for polishing a semiconductor wafer or the like. Specifically, the technology is applied to mirrorization and thickness adjustment processes of a semiconductor wafer, and aims to ensure the flatness of the wafer surface by effectively removing by-products generated during polishing in the process of manufacturing semiconductor devices. BACKGROUND

[0002] When forming a transistor or the like and a wiring structure on the surface of a semiconductor wafer such as silicon (Si), silicon carbide (SiC), or gallium nitride (GaN), a photolithography process is used to transfer a pattern defining the element structure and wiring area to the wafer by using an exposure device. At this time, if the wafer surface is not flat enough, the pattern cannot be accurately transferred due to the depth of field limitation of the optical system of the exposure device. A transfer error can cause a deviation in the size or an abnormality in the shape of the pattern, which can further cause fatal defects such as open circuits or short circuits in the finally formed element structure and wiring. Therefore, in the mirrorization and thickness adjustment processes of a semiconductor wafer, a CMP device is widely used to achieve high flatness of the wafer surface over a wide range. The CMP technology, as the only practical planarization process, can simultaneously and precisely adjust the wafer surface topography from the micron level to the nanometer level.

[0003] In addition, in the process of manufacturing semiconductor devices, a transistor element and a wiring structure or the like can be stacked on the wafer surface. In the process flow of forming such a multi-layer stacked structure, in order to eliminate the high and low undulations generated by each newly added layer and to provide a planarized wafer surface basis for subsequent process steps, a polishing process based on CMP processing also needs to be implemented multiple times.

[0004] When using a CMP device for chemical mechanical polishing processing, the polishing liquid needs to be first soaked on the surface of the polishing pad, and then the polishing head carrying the wafer is pressed onto the polishing plate. By rotating and sliding the polishing head and the polishing plate relative to each other, precise polishing of the wafer is achieved. The polishing liquid is a liquid slurry used in the CMP process, which contains chemical substances and polishing particles that match the composition, structure, and polishing purpose of the object to be polished. This process achieves planarization of the wafer surface by synergistically using mechanical polishing and chemical reactions induced by the chemical components contained in the polishing liquid.

[0005] In recent years, with the continuous progress of extreme ultraviolet lithography (EUV) technology and three-dimensional packaging technology, the substrate such as silicon wafer used in semiconductor device manufacturing process needs to meet the requirement of ultra-high flatness on the order of nanometers. In order to meet such stringent requirements, the industry is focusing on the use of new abrasive-free polishing liquid to implement abrasive-free CMP technology, which is a technology that realizes the planarization of the substrate surface mainly by chemical action of the material. Abrasive-free CMP has the advantage of not easily producing fine scratches (microscopic scratches) on the surface of the object to be polished due to less mechanical action; but at the same time, it faces the new problem that the by-products such as polishing debris and reaction products generated during polishing are easily retained in the gap between the polishing pad and the object to be polished. Once such by-products are retained, it will hinder the supply of new polishing liquid to the surface of the object to be polished, causing the chemical reaction to be inhibited. The problem caused thereby is that not only will the polishing rate be significantly reduced, but the polishing rate will also become unstable over time, making it difficult to obtain the desired flatness effect.

[0006] To solve the above problems, the industry has proposed various technical solutions. For example, a vacuum suction nozzle is attached to the surface of the polishing pad to directly suck the by-products and used polishing liquid off the surface of the polishing pad (see US6190236B1, US9375825B2). However, although these technologies are effective in removing by-products from the surface of the polishing pad, it is difficult to directly and efficiently remove by-products present at the interface between the wafer and the polishing pad during polishing.

[0007] In addition, it is also known to use a porous material to make the polishing pad (JP5596030B2, JP4147330B2). Such a porous pad can store polishing liquid in the internal pores to achieve a stable polishing effect. However, if only this kind of porous pad is used, the by-products are easy to accumulate and difficult to discharge once they penetrate into the interior of the pad. When the accumulation amount is too large to cause the pores to be blocked, the polishing ability will be significantly reduced, so that the pad has to be replaced frequently. Frequent replacement of the pad will result in reduced production efficiency, increased equipment downtime, and increased consumable costs. SUMMARY

[0008] The present application is proposed in view of the problems of the prior art, and aims to efficiently and actively remove the by-products retained in the polishing area and the interior of the polishing pad without interrupting the polishing operation during the chemical mechanical polishing process. Thus, the present application aims to provide a wafer polishing device and a polishing method that can continuously maintain a clean polishing environment, achieve a stable and efficient polishing rate, and improve the surface quality of the object to be polished.

[0009] To solve the above technical problems, in a first aspect, the application provides a wafer polishing device, comprising: a polishing head unit for holding and rotating a wafer; a polishing plate unit oppositely arranged with the polishing head unit, the surface of the polishing plate unit opposite to the polishing head unit is configured with a polishing pad; wherein the polishing pad is made of a porous material, and the polishing pad is provided with a plurality of through holes in the thickness direction; the polishing plate unit further comprises a suction mechanism arranged below the polishing pad, the suction mechanism is configured to be able to pass through the polishing pad to suction the by-products generated in the polishing process from the polishing area through the through holes.

[0010] Through the through holes opened on the polishing pad, the suction mechanism of the polishing plate unit can actively suck and remove the by-products in the polishing area. This structure can effectively prevent the accumulation and stagnation of by-products in the polishing area and the interior of the pad. Thus, the chemical reaction caused by the polishing liquid can be stably carried out without obstruction, thereby effectively preventing the polishing rate from decreasing and realizing efficient and stable polishing process. In addition, the improvement of the stability of the polishing process also helps to improve the surface flatness and reduce the surface roughness of the object being polished. In particular, it can effectively inhibit scratches and other defects caused by hard by-products such as polishing debris mixed into the polishing interface. In addition, since the excessive accumulation of by-products in the interior of the polishing pad is effectively inhibited, the plugging phenomenon in the interior of the polishing pad is reduced, so that the polishing performance of the polishing pad can be maintained for a long time. Not only can the workload caused by trimming the polishing pad be reduced, but also the service life of the polishing pad itself can be prolonged, thereby helping to reduce the cost of consumables and improve the operating efficiency of the equipment.

[0011] Optionally, the polishing plate unit comprises: a polishing plate, the polishing plate comprising a polishing surface for polishing the wafer, a bottom surface opposite to the polishing surface, and a plurality of by-product discharge holes penetrating from the polishing surface to the bottom surface, wherein the polishing surface is configured with the polishing pad; a by-product recovery plate, the by-product recovery plate being provided with a channel for recovering the by-products, the inlet of the channel being located on the upper surface of the by-product recovery plate and being communicated with the by-product discharge holes, and the lower surface of the by-product recovery plate being provided with a by-product suction hole, the channel being communicated with the suction mechanism through the by-product suction hole.

[0012] By opening the by-product discharge holes on the polishing plate and the channel for recovering the by-products on the by-product recovery plate, the suction mechanism can smoothly suck and discharge the by-products from the polishing surface of the polishing plate, thereby improving the output efficiency of the by-products.

[0013] Optionally, the channel in the by-product recovery plate is divided into a plurality of independent closed loops, and each independent closed loop is respectively provided with a separate suction mechanism.

[0014] By respectively arranging a separate suction mechanism on each independent closed loop, each region can be controlled independently, which is convenient for coping with various working conditions, improves compatibility, and in addition, can improve the overall working efficiency of the equipment.

[0015] Optionally, the suction mechanism comprises a vacuum source, a suction pipeline and a control valve, the control valve is installed on the suction pipeline, the vacuum source is communicated with the by-product suction hole through the suction pipeline, and the control valve controls the opening and closing of the suction pipeline.

[0016] The suction force is provided by the vacuum source, and the control valve controls the opening and closing of the suction pipeline, thereby providing a simple and efficient suction force output structure.

[0017] Optionally, the suction mechanism further comprises a negative pressure regulating valve installed on the suction pipeline to regulate the gas negative pressure in the suction pipeline, or the suction mechanism further comprises a frequency converter electrically connected with the vacuum source to regulate the output power of the vacuum source.

[0018] By setting the negative pressure regulating valve or the frequency converter, the output power of the suction mechanism is quickly controlled, the compatibility is improved, and a basis is provided for subsequent adaptive adjustment of the suction force.

[0019] Optionally, the aperture range of the through hole is 0.05-2.0 mm, and / or the opening density range of the through hole is 0.5-100 / cm².

[0020] By limiting the aperture and opening density of the through hole, the work efficiency of discharging by-products is improved without affecting the mechanical strength of the polishing pad and the retention characteristics of the polishing liquid.

[0021] Optionally, the wafer polishing device further comprises a sensor for detecting the accumulation amount of by-products, and a control unit for optimizing the suction pressure of the suction mechanism based on the detection information of the sensor.

[0022] Through the cooperation of the sensor and the control unit, the suction pressure is adjusted in real time to more targetedly attract the by-products generated by the chemical reaction.

[0023] Optionally, the control unit adopts artificial intelligence technology to predict the accumulation amount of by-products based on the information obtained by the sensor and historical polishing data, and to adjust the suction pressure of the suction mechanism in real time.

[0024] By adopting the artificial intelligence technology, the automatic adjustment effect of the suction pressure of the suction mechanism is realized, and the production efficiency and the automation level of the equipment are improved.

[0025] In a second aspect, the application also provides a wafer polishing method, which comprises: polishing a wafer held by a head unit on a polishing plate unit provided with a polishing pad made of a porous material and provided with a plurality of through holes in the thickness direction; and sucking and removing by-products from the polishing area through the polishing pad through the through holes.

[0026] The by-product generated during the polishing of the wafer is allowed to flow into the through holes of the polishing pad made of porous material and then be discharged by the suction mechanism, so as to effectively prevent the accumulation and retention of the by-product in the polishing area and the pad body, thereby ensuring the stable chemical reaction of the polishing liquid and the wafer surface, and achieving efficient and stable polishing, and prolonging the service life of the polishing pad, and ultimately reducing the cost of consumables and improving the operation efficiency of the equipment.

[0027] Optionally, the suction of the by-product from the polishing area through the through holes and the penetration of the polishing pad include: independently controlling the suction pressure of each of the plurality of independent closed circuits arranged below the polishing plate unit.

[0028] By independently controlling the suction pressure of each of the plurality of independent closed circuits arranged below the polishing plate unit, the compatibility of the equipment is improved, and the working efficiency of the equipment is improved.

[0029] Optionally, the independently controlling the suction pressure of each of the plurality of independent closed circuits arranged below the polishing plate unit includes: detecting the accumulation level of the by-product in each closed circuit by a sensor, and optimizing the suction pressure of each closed circuit based on the detection result.

[0030] By detecting the accumulation level of the by-product in each closed circuit by a sensor and optimizing the suction pressure of each closed circuit based on the detection result, the suction pressure is adjusted in real time to more effectively attract the by-product generated by the chemical reaction.

[0031] Optionally, the optimizing the suction pressure of each closed circuit based on the detection result includes: using artificial intelligence technology to predict the accumulation level of the by-product based on the information obtained by the sensor and historical polishing data, and adjusting the suction pressure in real time.

[0032] By using artificial intelligence technology, the suction pressure of the suction mechanism is automatically adjusted, and the production efficiency and the automation level of the equipment are improved. DETAILED DESCRIPTION

[0033] Figure 1 FIG. 1 is a structural schematic diagram of a wafer polishing device according to a first embodiment of the present application; FIG. 2(a)-2(b) are structural schematic diagrams of a polishing plate according to the first embodiment of the present application; FIG. 3(a)-3(c) are structural schematic diagrams of a by-product recovery plate according to the first embodiment of the present application; FIG. 4(a)-4(b) are structural schematic diagrams of a typical porous polishing pad according to the present application; Figure 5Fig. 1 is a schematic diagram of a wafer polishing apparatus according to a first embodiment of the present application. Figs. 6(a)-6(b) are schematic diagrams of a polishing plate according to a second embodiment of the present application. Figs. 7(a)-7(c) are schematic diagrams of a by-product recovery plate according to the second embodiment of the present application. Figs. 8(a)-8(c) are schematic diagrams of another by-product recovery plate according to the second embodiment of the present application. Figure 9 Fig. 9 is a block diagram of a wafer polishing apparatus equipped with an advanced process control system.

[0034] Figures 1-9 The wafer polishing apparatus according to the present application includes: 1. a polishing apparatus; 2. a polishing head unit; 3. a polishing plate unit; 10. a polishing head; 11. a wafer holding portion; 12. a holding ring; 13. a polishing head rotation shaft; 14. a polishing plate; 15. a by-product recovery plate; 16. a polishing plate rotation shaft; 17. a porous polishing pad; 18. a by-product discharge hole; 19. a connecting portion; 20. a by-product suction hole; 21. a control unit; 22. a sensor; P1, P2, P3, a vacuum pump; V1, V2, V3, a valve; W, a wafer (polishing target). DETAILED DESCRIPTION

[0035] In order to make the above objects, features and advantages of the present application more clear and comprehensible, the present application will be described in further detail below with reference to the accompanying drawings and specific embodiments. It should be noted that the same or corresponding components are denoted by the same reference numerals in the drawings, and repeated descriptions are appropriately omitted.

[0036] Figure 1 A wafer polishing apparatus 1 (hereinafter referred to as "polishing apparatus 1") according to a first embodiment of the present application is shown. The polishing apparatus 1 is suitable for chemical mechanical polishing (CMP) of a disc-shaped polishing target such as a semiconductor wafer W. The polishing apparatus 1 includes a polishing head unit 2 and a polishing plate unit 3.

[0037] In one possible implementation, the polishing head unit 2 is used to hold the wafer W during polishing, press the wafer W against the polishing pad 17 of the polishing plate unit 3, and drive the wafer W to rotate and oscillate. The holding can be clamping, bearing, fixing, pressing, or limiting the position of the wafer W, etc. The polishing plate 14 is the main component of the polishing plate unit, and the polishing plate unit 3 is a platform structure that polishes the wafer W by rotating the polishing plate 14 and using the polishing pad 17 provided on the polishing plate 14.

[0038] First, the specific structure of the polishing head unit 2 is described in detail. The polishing head unit 2 mainly includes a polishing head 10, a wafer holding part 11, and a holding ring 12. The main part of the polishing head unit 2 includes the polishing head 10. The upper end of the polishing head 10 is provided with a polishing head rotating shaft 13 for driving the polishing head 10 to rotate, and the inside of the polishing head rotating shaft 13 is configured with a driving shaft for driving the polishing head 10 to rotate, which is driven by a motor (not shown in the figure). A holding mechanism for holding the wafer W, i.e., the wafer holding part 11, is provided at the lower part of the polishing head unit 2. As a component for holding the wafer W, the wafer holding part 11 can be made of materials such as ceramic plates, gaskets, or film sheets.

[0039] When the wafer holding part 11 is a ceramic plate, an adhesive such as wax needs to be applied to the back side opposite to the polishing surface of the wafer W, and then the wafer is pasted on the ceramic plate to achieve fixation. If the wafer holding part 11 uses a gasket, no wax material is needed, but the wafer is fixed on the surface of the gasket by adsorption.

[0040] A flexible material, such as a diaphragm, is further provided above the ceramic plate or the gasket in the wafer holding part 11. Thus, the pressure applied by the inner chamber of the polishing head 10 can be effectively absorbed and adjusted. A ring-shaped holding ring 12 is provided below the wafer holding part 11 relative to the position of the periphery of the wafer W. The holding ring 12 is used to form a surrounding constraint fixation for the wafer W as the polishing object.

[0041] The structure of the polishing plate unit 3 is described below. The polishing plate unit 3 in this embodiment includes a polishing plate 14, a by-product recovery plate 15, and a polishing plate rotating shaft 16 for driving the polishing plate to rotate. In addition, in the polishing plate unit 3, a suction mechanism is provided below the polishing pad 17 for sucking and discharging the by-products generated in the polishing area.

[0042] Fig. 2 shows the structure of the polishing plate 14 in the first embodiment of the present application. Fig. 2(a) is a plan view and Fig. 2(b) is a sectional view along the line X-X'. The polishing plate 14 is arranged opposite to the polishing head 10 and has a porous polishing pad 17 described below attached to the upper surface of the polishing plate 14. In addition, the polishing plate 14 has a plurality of by-product discharge holes 18 formed therethrough from the polishing surface to the back surface of the polishing plate 14.

[0043] Fig. 3 shows the structure of the by-product recovery plate 15 in the first embodiment of the present application. Fig. 3(a) is a plan view, Fig. 3(b) is a bottom view, and Fig. 3(c) is a sectional view along the line X-X'. The by-product recovery plate 15 is arranged below the polishing plate 14. The by-product recovery plate 15 has a channel (tunnel-like passage) for recovering the by-product and the top of the by-product recovery plate 15 is connected to the plurality of by-product discharge holes 18 of the polishing plate 14 by a connecting portion 19. The connecting portion 19 can be an inlet of the channel formed in the by-product recovery plate 15 or a connecting member arranged above the inlet, such as a sealing head. In one possible embodiment, the upper surface of the by-product recovery plate has a plurality of feed grooves, the inlets of the channels are arranged at the lower ends of the feed grooves and communicate with the feed grooves, and the by-product discharge holes are arranged at the upper ends of the feed grooves and communicate with the feed grooves. Alternatively, the inlets of the channels and the by-product discharge holes are arranged one-to-one. By arranging the feed grooves, the by-product can be temporarily stored after flowing out of the by-product discharge holes and then accurately fed into the by-product recovery plate. Alternatively, the inlets of the channels and the by-product discharge holes are arranged one-to-one, so that the joint between the by-product recovery plate and the polishing plate is more airtight. Of course, when the by-product recovery plate and the polishing plate are installed, a sealing member such as a sealing strip is used to ensure the airtightness between the by-product recovery plate and the polishing plate.

[0044] In addition, the bottom surface of the by-product recovery plate 15 has a by-product suction hole 20 for sucking the by-product by a suction mechanism in the subsequent process, and the channel formed in the by-product recovery plate 15 communicates with the suction mechanism through the by-product suction hole 20. The polishing plate rotating shaft 16 is driven to rotate synchronously as a whole by a motor (not shown in the figure). The suction pipeline of the suction mechanism communicates with the vacuum pump P1 through a coaxial multi-pipeline rotating joint built in the polishing plate rotating shaft 16. The rotating joint can include a negative pressure supply pipeline, a liquid discharge pipeline, a temperature adjusting medium pipeline, and a flushing liquid (cleaning liquid) pipeline, which are independent of and do not interfere with each other.

[0045] One of the core features of the present application is that a porous polishing pad and a suction mechanism arranged below the porous polishing pad are used. Fig. 4 shows an example of a typical structure of the porous polishing pad 17 of the present application. Fig. 4(a) is a plan view and Fig. 4(b) is a sectional view along the line X-X'. The porous polishing pad 17 can be made of a porous material such as foamed polyurethane or non-woven fabric impregnated with polyurethane.

[0046] As shown in FIG. 4, the porous material has micro-pores formed therein in a random or semi-regular distribution. These pores play a key role in storing slurry during polishing and stably supplying the slurry between the wafer and the polishing pad. The size of the pores is generally in the order of several hundred nanometers to several tens of micrometers, and they are connected to each other to form a network structure depending on the actual manufacturing conditions. This pore network, which is a microscopically connected structure inherent to the porous material, allows the pores to be connected to each other in the thickness direction of the polishing pad.

[0047] In the porous pad shown in FIG. 4, the micro-pores are connected to each other to form a plurality of through-holes extending in the thickness direction of the pad. Preferably, the through-holes are substantially uniformly distributed throughout the porous pad or arranged in a predetermined pattern. The through-holes are main flow passages for fluidly connecting the polishing region to the suction mechanism described below.

[0048] In addition, the polishing pad according to the present application finally needs to have a plurality of through-holes extending in the thickness direction. If the original pore network does not extend throughout the thickness of the polishing pad, through-holes can be intentionally formed in the thickness direction between the polishing surface and the back surface of the polishing pad 17 by mechanical processing. These through-holes can be formed by laser drilling, micro-drilling, press forming, or a sacrificial template method, etc., in a predetermined diameter and arrangement, thereby ensuring reliable fluid communication. In this case, the diameter of the through-holes can be freely set, and the cross-sectional shape of the through-holes can be circular, slot-shaped, or polygonal. In one possible embodiment, the diameter of the through-holes can be set to 0.05 to 2.0 mm, but is not limited thereto. The opening density of the through-holes can be set without affecting the mechanical strength of the polishing pad and the slurry retention characteristics, for example, the opening density can be set to 0.5 to 100 / cm2, but is not limited thereto.

[0049] In the present embodiment, the suction mechanism includes a vacuum pump P1 (e.g., a dry pump) connected to the byproduct suction hole 20 of the byproduct recovery plate 15, a suction line, and a control valve V1 that controls the opening and closing of the suction line. Note that instead of a vacuum pump, a jet-type vacuum generator can be used as the vacuum source. In addition to the valve V1 that controls the opening and closing of the suction line, a negative pressure regulating valve (e.g., a proportional control valve, a pressure reducing valve, etc.) can be provided on the suction line to regulate the negative pressure of the gas in the suction line, or a frequency converter can be provided and electrically connected to the vacuum source to regulate the rotational speed of the vacuum source. In this way, the target negative pressure curve including the pressure increasing, maintaining, and decreasing stages can be controlled in accordance with the polishing progress and the generation of byproducts. The specific path of the suction line is as follows: the fluid recovered from the polishing interface flows through the through holes of the porous polishing pad 17, the byproduct discharge hole 18 of the polishing plate 14, the internal passage of the byproduct recovery plate 15, and the byproduct suction hole 20 in this order, enters a rotary joint (not shown in the figure) in the polishing plate rotary shaft 16, and is finally connected to the suction line and the vacuum pump P1 through the rotary joint.

[0050] The flow passage in the byproduct recovery plate 15 is connected to the through holes of the porous polishing pad 17 through the byproduct discharge hole 18 of the polishing plate 14, and is used to efficiently discharge the suctioned byproducts to the outside. Note that the "suction mechanism" defined in the present specification includes at least the following elements: a negative pressure gas source (a vacuum pump or a vacuum generator) connected to the byproduct suction hole 20, a suction line, and a control valve, and the installation position of the negative pressure gas source is not limited to inside the polishing plate unit 3. The negative pressure gas source can be installed at other positions and connected to the byproduct suction hole 20 through an air pipe and an air flow passage.

[0051] The polishing process performed by the polishing apparatus 1 includes the following steps: first, the polishing head 10 fixes the wafer W and applies a predetermined pressure to make the wafer W adhere to the upper surface of the porous polishing pad 17 on the polishing plate unit 3.

[0052] Next, the polishing head 10 and the polishing plate unit 3 are driven to rotate by the polishing head rotary shaft 13 and the polishing plate rotary shaft 16, respectively, so that the two generate relative motion.

[0053] Meanwhile, slurry (polishing liquid) is supplied to the surface of the porous polishing pad 17 through the slurry supply nozzle. By this relative movement, chemical and mechanical polishing is performed on the surface of the wafer W. The polishing liquid can be one containing abrasive grains or one not containing abrasive grains (abrasive grain-free). In the case of using the abrasive grain-free one, a reaction layer can be formed on the surface of the wafer W by a chemical liquid containing an oxidizing agent, a chelating agent, a pH adjuster, and the like, and material removal can be achieved by a mechanism such as dissolution or peeling of the reaction layer. By-products generated at this time exist together with the polishing liquid in the interface region between the porous polishing pad 17 and the wafer W (a dynamic interaction region in which the porous polishing pad 17 directly contacts the wafer W). In the present embodiment, the flow passage inside the by-product recovery plate 15 is made to have a negative pressure by activating the vacuum pump PI during polishing. This negative pressure acts on the polishing region through the through-holes of the polishing plate 14 and the porous polishing pad 17, thereby generating a strong suction force toward the lower side of the pad body.

[0054] Under the action of this suction force, the by-products are first sucked into the pores of the porous polishing pad 17 together with the polishing liquid by capillary phenomenon; then, the by-products inside the porous polishing pad 17 are forcibly sucked through the through-holes and finally discharged into the flow passage of the by-product recovery plate 15. Note that the "suction" and "sucking" described in the present specification include various modes of driving by a pressure difference generated by forming a negative pressure field or in combination with upstream pressurization. That is, the suction force can be generated not only by a vacuum but also by a suction action induced by a negative pressure or a pressure difference.

[0055] In this way, it is possible to actively remove the by-products generated in the polishing interface and inside the porous polishing pad 17 from the polishing region in real time. As a result, new polishing liquid is always applied to the surface of the wafer, and the phenomenon of hindering chemical reaction is effectively suppressed, so that a stable polishing rate can be maintained.

[0056] Further, the shape of the flow passage provided on the by-product recovery plate 15 is not particularly limited. For example, as shown in FIG. 3, a spiral groove extending from the center of the plate body to the outer periphery can be formed on the by-product recovery plate 15. At this time, it is preferable that the layout of the by-product discharge holes 18 of the polishing plate 14 be adapted to the shape of the flow passage provided on the by-product recovery plate. Specifically, as shown in FIG. 2, in the present embodiment, the layout of the by-product discharge holes 18 of the polishing plate 14 is designed as a spiral groove extending from the center of the plate body to the outer periphery. By adopting this shape design, the by-products can be efficiently guided to the discharge ports located in the central region or the outer peripheral region by the centrifugal force generated when the plate is rotated.

[0057] Hereinafter, the present application will be described in detail with reference to the drawings. Figure 5A second embodiment of the present application will be described. The main difference between this embodiment and the first embodiment is the structure of the polishing plate unit 3. Specifically, the passage inside the by-product recovery plate 15 is divided into a plurality of independent closed circuits that isolate the fluids from each other, and as shown in Figure 5 each of the independent closed circuits is respectively provided with a separate suction mechanism (V1 to V3, P1 to P3).

[0058] FIG. 6 shows the structure of the polishing plate 14 in the second embodiment. FIG. 6(a) is a plan view, and FIG. 6(b) is a sectional view along the line X-X'. Since the passage inside the by-product recovery plate 15 is divided into a plurality of independent closed circuits that isolate the fluids from each other, the distribution of the by-product discharge holes 18 in the polishing plate 14 shown in FIG. 6 is adjusted compared to that in FIG. 2, and the rest of the structure is the same as that of the polishing plate 14 shown in FIG. 2.

[0059] FIG. 7 shows the structure of the by-product recovery plate 15 in the second embodiment of the present application. FIG. 7(a) is a plan view, FIG. 7(b) is a bottom view, and FIG. 7(c) is a sectional view along the line X-X'. The by-product recovery plate 15 shown in FIG. 7 has a structure in which the plate body is divided into sectors by a radial cut, i.e., the closed flow passages inside the by-product recovery plate 15 are distributed in a sector shape. At least one by-product suction hole 20 is provided in each sector. The rest of the structure is the same as that of the by-product recovery plate 15 shown in FIG. 3.

[0060] In this embodiment, the independent suction mechanisms include vacuum pumps (P1, P2, P3) and valves (V1, V2, V3) that are respectively connected to the closed flow passages. Thus, the suction pressure of each region can be independently controlled and dynamically adjusted during the polishing process. It is worth noting that, during the polishing of a wafer, the relative speed of the wafer edge region with respect to the polishing pad is generally higher than that of the center region, so that more by-products are generated in the edge region.

[0061] With this embodiment, the suction pressure can be optimally adjusted by region in response to the uneven distribution of by-products. For example, the suction pressure can be selectively increased in regions where the accumulation of by-products is expected to be more, and the suction pressure can be reduced in regions where the accumulation of by-products is expected to be less, thereby achieving fine control and adjustment. Thus, the suction efficiency can be maximized over the entire wafer surface, unnecessary power consumption can be suppressed, and the by-products on the entire wafer surface can be more efficiently removed. This improvement further enhances the uniformity of the polishing process.

[0062] In the present embodiment, the shape of the closed flow path in the by-product recovery plate is not limited to the structure shown in FIG. 7, in which the plate is divided into sectors in a radial manner. As shown in FIG. 8, the closed flow path in the by-product recovery plate 15 can also be divided in a concentric manner, or other shapes. The distribution of the closed flow path in the by-product recovery plate 15 is not limited herein. The distribution of the closed flow path in the by-product recovery plate 15 can be selected according to the polishing conditions, the wafer characteristics, and the distribution of the by-products to be removed.

[0063] In other embodiments that can be implemented, the present application also encompasses embodiments in which sensors and artificial intelligence (AI) are introduced to achieve higher-order process control. Figure 9 The overall architecture of the polishing apparatus 1 equipped with such a control system is shown in the block diagram.

[0064] In the present embodiment, a sensor 22 for detecting the amount of by-product accumulation is provided on the suction line of each region. As an alternative, the sensor can be a flow monitor for monitoring the flow rate of the liquid flowing through the filter of the suction line, an optical sensor for measuring the turbidity of the liquid being sucked, or a differential pressure sensor for detecting the differential pressure of the filter, etc. According to the actual working conditions, additional detection functions of process parameters such as conductivity, pH value, and temperature can also be further added.

[0065] The detection signal of the sensor 22 is input in real time to the control unit 21. Based on the received detection information of the sensor, the control unit determines the degree of by-product accumulation in each region in real time. Specifically, the control unit 21 calculates a by-product accumulation index (CI) according to the received detection data, and uses the index to make decisions on the control strategy of each region.

[0066] Then, based on the by-product accumulation index (CI), feedback control is implemented through the slurry flow adjusting device (not shown), the valves V1, V2, V3 of each region, and the vacuum pumps P1, P2, P3. In this way, the slurry flow and the suction pressure of each region can be stabilized within the set range, so as to achieve dynamic balance of the fluid environment.

[0067] As a further embodiment, artificial intelligence (AI) can also be loaded in the control unit 21. In this case, the AI predicts the degree of by-product accumulation based on the real-time data provided by the sensor 22 and the historical polishing data, and adjusts the suction pressure in real time. Specifically, the AI predicts the future value of the by-product accumulation index (CI), and implements feedforward compensation control accordingly. The historical polishing data includes information such as the polishing process parameter recipe (e.g., polishing pressure, rotation speed, etc.), the motor load current for driving the rotation shaft 13 of the polishing head and the rotation shaft 16 of the polishing plate, the type of wafer, and the pattern density distribution, etc.

[0068] The byproduct accumulation index (CI) described in the specification refers to a dimensionless parameter representing the degree of accumulation or clogging in the byproduct recovery channel in each region, and the value is calculated based on at least one of the detected values including at least differential pressure, flow rate, and turbidity. The application does not limit the calculation method of the byproduct accumulation index, and the calculation method of the index can use any of the following methods: (i) a method of weighted synthesis of normalized values of reference values; (ii) a deviation (prediction residual) analysis method between the normal values estimated by the process recipe, etc.; (iii) a calculation method by a machine learning model; or a combination of the above methods. The calculated CI value is used as a key parameter for setting the partition suction pressure, triggering conditions for flushing operation, and alarm threshold determination criteria.

[0069] Artificial intelligence (AI) can master the correlation between byproduct accumulation state and parameters by analyzing these massive data, and then build a high-precision prediction model. Based on the model, the system can real-time and autonomously analyze the current grinding conditions, dynamically optimize and accurately control the suction pressure to the best state.

[0070] By using a feedback control mechanism with such CI as a general index, and combining with the predictive feedforward control realized by AI, the system can quickly respond to slight fluctuations in process conditions, thereby realizing a chemical mechanical polishing (CMP) process with extremely high stability and reproducibility.

[0071] In summary, although the embodiments of the application have been described, the application is not limited to these specific examples. For example, the material selection of the polishing pad, the shape and density of the through holes, the detailed structure of the suction mechanism, and the number and layout of the partitions can be appropriately adjusted without departing from the scope of the application.

[0072] The wafer chemical mechanical grinding device and method disclosed in the application can be widely applied to the planarization processing of various polished materials such as silicon wafers, compound semiconductor wafers, glass substrates, and substrates for other electronic devices.

[0073] In addition, in advanced semiconductor device manufacturing processes such as planarization of interlayer dielectric film (ILD), preparation of shallow trench isolation structure (STI), formation of copper (Cu) interconnection wiring structure, etc., which have strict requirements on flatness, the technology can also significantly improve production efficiency and yield.

[0074] In addition, the polishing apparatus and the polishing method according to the present application can be applied regardless of whether or not the polishing liquid contains abrasive grains. In particular, in the CMP process without abrasive grains, although the gelled product and the soluble substance generated by the chemical reaction are liable to be retained at the interface, they are immediately recovered through the through holes of the porous polishing pad by the differential pressure suction, so that the polishing rate can be stably maintained and the uniformity of the wafer surface can be improved. In the CMP process with the polishing liquid containing abrasive grains, the design is also helpful to the recycling of the hard particles and the effective removal of the scratch source.

[0075] The above description of the present application is sufficiently detailed to have a certain particularity. It should be understood by those skilled in the art that the description in the embodiments is only exemplary, and all changes made without departing from the true spirit and scope of the present application should belong to the protection scope of the present application. For example, the concepts of flow channel and passage can be replaced. The scope of protection claimed by the present application is defined by the claims, not by the above description in the embodiments.

Claims

1. A wafer grinding apparatus, characterized in that, The wafer grinding apparatus includes: A grinding head unit used to hold and rotate wafers; A polishing plate unit is disposed opposite to the grinding head unit, and a polishing pad is disposed on the surface of the polishing plate unit opposite to the grinding head unit; The grinding pad is made of a porous material and has several through holes in the thickness direction. The polishing plate unit also includes a suction mechanism disposed below the polishing pad, the suction mechanism being configured to remove byproducts generated during the polishing process of the wafer from the polishing area through the through hole and the polishing pad.

2. The wafer grinding apparatus as described in claim 1, characterized in that, The polishing plate unit includes: A polishing plate, the polishing plate including a polishing surface for polishing a wafer, a bottom surface opposite to the polishing surface, and a plurality of by-product discharge holes extending from the polishing surface to the bottom surface, wherein a polishing pad is disposed on the polishing surface; A by-product recovery plate is provided with a channel for recovering by-products. The entrance of the channel is located on the upper surface of the by-product recovery plate and communicates with the by-product discharge hole. A by-product suction hole is provided on the lower surface of the by-product recovery plate. The channel communicates with the suction mechanism through the by-product suction hole.

3. The wafer grinding apparatus as described in claim 2, characterized in that, The channels within the byproduct recovery plate are divided into multiple independent closed loops, and each of these independent closed loops is equipped with a separate suction mechanism.

4. The wafer grinding apparatus as described in claim 2, characterized in that, The suction mechanism includes a vacuum source, a suction pipeline, and a control valve. The control valve is installed on the suction pipeline. The vacuum source is connected to the by-product suction hole through the suction pipeline. The control valve controls the opening and closing of the suction pipeline.

5. The wafer grinding apparatus as described in claim 4, characterized in that, The suction mechanism also includes a negative pressure regulating valve, which is installed on the suction pipe to regulate the negative pressure of the gas in the suction pipe; Alternatively, the suction mechanism may further include a frequency converter electrically connected to the vacuum source to adjust the output power of the vacuum source.

6. The wafer grinding apparatus as described in claim 2, characterized in that, The diameter of the through hole ranges from 0.05 to 2.0 mm, and / or the opening density of the through hole ranges from 0.5 to 100 holes / cm².

7. The wafer grinding apparatus according to any one of claims 1-6, characterized in that, The wafer grinding apparatus also includes a sensor for detecting the accumulated amount of byproducts, and a control unit for optimizing the suction pressure of the suction mechanism based on the detection information from the sensor.

8. The wafer grinding apparatus as described in claim 7, characterized in that, The control unit uses artificial intelligence technology to predict the accumulation of by-products based on information acquired by the sensors and historical grinding data, and adjusts the suction pressure of the suction mechanism in real time.

9. A wafer grinding method, characterized in that, The method includes: On a polishing plate unit with a polishing pad made of porous material on its surface and a number of through holes in the thickness direction, a wafer held by a polishing head unit is polished. And to remove byproducts from the grinding area and pass them through the through-hole into the grinding pad.

10. The wafer grinding method as described in claim 9, characterized in that: The process of removing byproducts from the grinding area and penetrating the grinding pad through the through hole includes: independently controlling the suction pressure of several independent closed loops located below the polishing plate unit.

11. The wafer grinding method as described in claim 10, characterized in that: The method of independently controlling the suction pressure of the multiple independent closed loops located below the polishing plate unit includes: detecting the accumulation level of by-products in each closed loop through a sensor, and optimizing the suction pressure of each closed loop based on the detection results.

12. The wafer grinding method as described in claim 11, characterized in that: The optimization of the suction pressure of each closed loop based on the detection results includes: using artificial intelligence technology to predict the accumulation level of the byproducts based on the information obtained by the sensor and historical grinding data, and adjusting the suction pressure in real time.

Images