Megasonic assisted lapping plate and lapping assembly

Abstract

The application provides a megasonic-assisted polishing disc and a polishing assembly. The megasonic-assisted polishing disc comprises a polishing disc body, a first surface of which is provided with a containing groove; an upper disc, which covers the first surface of the polishing disc body and is detachably connected with the polishing disc body; a megasonic generator; a transducer, which is arranged in the containing groove and is electrically connected with the megasonic generator; a matching layer, which is fixedly connected with a side surface of the transducer in the containing groove and is in abutment with the upper disc; a transmission shaft, which is fixedly connected with the polishing disc body; and a driving assembly, which is drivingly connected with the transmission shaft and drives the transmission shaft to rotate. By means of the megasonic generator, the polishing disc body and the polishing pad fixed thereon are driven to vibrate at a high frequency, so that the polishing liquid in the polishing pad cavity vibrates at a high frequency, and the polishing effect that can be achieved by a large flow of the polishing liquid in the traditional way is achieved under a smaller flow. Meanwhile, under the action of the high-frequency vibration and the micro-flow of the polishing liquid, large-particle impurities in the polishing pad cavity leave the polishing pad, and the wafer is less scratched.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of semiconductor integrated circuit chip manufacturing, in particular to a megasonic-assisted grinding disc and grinding assembly. BACKGROUND

[0002] In the past two decades, the semiconductor industry has developed rapidly with Moore's Law, and the feature size of integrated circuits has been continuously reduced. The wire width from 0.18 μm to 5 / 7 nm marks that integrated circuits have entered the nanometer era. Nanoscale chips require high performance, high integration, high speed, and stability, and the planarity requirement of the interconnection material of each layer of the integrated circuit has also entered the nanometer level.

[0003] The deposition technology of each layer of material in the modern integrated circuit wafer includes physical vapor deposition (PVD), chemical vapor deposition (CVD), plasma enhanced chemical vapor deposition (PECVD), and electrochemical plating (ECP). Due to the technical limitations of the deposition technology itself, subsequent surface planarization treatment of the deposited material is required. Planarization technology can effectively remove surface topography and surface defects that do not meet the circuit requirements during material deposition, such as height unevenness, surface roughness, material coalescence, lattice damage, scratches, and contamination. Chemical mechanical planarization or chemical mechanical polishing (CMP) is a common technology used to polish or planarize workpieces such as semiconductor wafers. In traditional chemical mechanical polishing (CMP), the wafer is fixed on the polishing head, and the polishing pad is fixed on the polishing disc. During polishing, the wafer is in direct contact with the polishing pad, and a controllable pressure is provided between them. The polishing liquid is supplied by a polishing liquid supply arm, and the wafer and the polishing pad rotate at different speeds in the same direction. The thin film on the wafer is polished under the relative motion of the polishing pad and the polishing head until the preset thickness is reached. In this process, a large amount of polishing liquid remains in the polishing pad pocket, the utilization rate is low, and large particle impurities can easily hide in the polishing pad pocket, causing damage to the wafer. SUMMARY

[0004] Therefore, the present application provides a megasonic-assisted grinding disc and grinding assembly. The grinding disc body and the polishing pad fixed thereon are driven by the megasonic wave to vibrate at a high frequency. The polishing liquid in the polishing pad pocket vibrates at a high frequency, achieving the polishing effect of a large flow of traditional polishing liquid under a smaller flow, improving the utilization rate, and the large particle impurities in the polishing pad pocket leave the polishing pad under the action of high-frequency vibration and micro-flow of the polishing liquid, reducing the scratch of the wafer.

[0005] The megasonic-assisted polishing disc provided by the application comprises a polishing disc body, a first surface of the polishing disc body is provided with a containing groove, an upper disc covers the first surface of the polishing disc body and is detachably connected with the polishing disc body, a megasonic generator, a transducer arranged in the containing groove and electrically connected with the megasonic generator, a matching layer fixedly connected with the transducer and abutting against the upper disc, a transmission shaft fixedly connected with the polishing disc body, and a driving assembly drivingly connected with the transmission shaft and driving the transmission shaft to rotate.

[0006] Optionally, the megasonic-assisted polishing disc further comprises a polishing pad fixedly connected with a side surface of the upper disc away from the containing groove.

[0007] Optionally, a side surface of the polishing pad away from the upper disc is provided with a glue layer, and the polishing pad is gluedly connected with the upper disc.

[0008] Optionally, the megasonic-assisted polishing disc further comprises an end point detection device for monitoring the thickness of a film layer on a wafer surface, and the end point detection device is arranged in the containing groove.

[0009] Optionally, the end point detection device comprises at least one of an optical end point detection device and an eddy current end point detection device.

[0010] Optionally, the transducer, the matching layer and the polishing disc body are coaxially arranged.

[0011] Optionally, the megasonic generator emits megasonic waves with a frequency of 850 KHz-1.4 MHz.

[0012] Optionally, the upper disc is bolted with the polishing disc body.

[0013] Optionally, a side surface of the matching layer away from the transducer is provided with a glue layer, and the matching layer and the transducer are gluedly connected.

[0014] The application further provides a polishing assembly comprising a polishing head, a polishing liquid supply arm and a polishing pad trimmer, and further comprising the megasonic-assisted polishing disc.

[0015] The above technical solution provided by the application has at least the following beneficial effects compared with the prior art:

[0016] Adopt the megasonic auxiliary grinding disc and grinding assembly of the application, drive the grinding disc body and the grinding pad fixed thereon high-frequency vibration by means of megasonic, then the grinding liquid in the grinding pad groove chamber high-frequency vibration, in the case of smaller flow can reach the grinding effect of traditional grinding liquid large flow, improve the utilization, at the same time, the large particle impurities in the grinding pad groove chamber leave the grinding pad under the action of high-frequency vibration and grinding liquid micro-flow, which can reduce the wafer scratch. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 The megasonic auxiliary grinding disc of the application is shown in the schematic diagram of one embodiment of the application.

[0018] Figure 2 The grinding assembly of the application is shown in the schematic diagram of one embodiment of the application.

[0019] Reference signs:

[0020] 1: grinding disc body; 2: upper disc; 3: megasonic generator; 4: transducer; 5: matching layer; 6: transmission shaft; 7: driving assembly; 8: grinding head; 9: grinding liquid supply arm; 10: grinding pad trimmer. DETAILED DESCRIPTION

[0021] The embodiments of the application will be further described below with reference to the drawings. In the description of the application, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer" and the like indicate the orientation or positional relationship shown in the drawings, and are only for the convenience of the simplified description of the application, and do not indicate or imply that the device or component referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the application. In addition, the terms "first", "second", "third" are only for the purpose of description, and cannot be understood as indicating or implying relative importance. Among them, the terms "first position" and "second position" are two different positions.

[0022] Figure 1 The megasonic auxiliary grinding disc of the application is shown in the schematic diagram of one embodiment of the application. As shown in Figure 1 The megasonic auxiliary grinding disc includes a grinding disc body 1, an upper disc 2, a megasonic generator 3, a transducer 4, a matching layer 5, a transmission shaft 6 and a driving assembly 7.

[0023] The first surface of the grinding disc body 1 is provided with a receiving groove; the upper disc 2 covers the first surface of the grinding disc body 1 and is detachably connected with the grinding disc body 1; the transducer 4 is arranged in the receiving groove and is electrically connected with the megasonic generator 3; the matching layer 5 is fixedly connected with the transducer 4 in the receiving groove and is in abutment with one side surface of the upper disc 2; the transmission shaft 6 is fixedly connected with the grinding disc body 1; and the driving assembly 7 is drivingly connected with the transmission shaft 6 to drive the transmission shaft 6 to rotate.

[0024] In use, the transducer 4 is placed in the receiving groove, the matching layer 5 is attached to and fixed on the surface of the transducer 4, the upper disc 2 is connected with the grinding disc body 1, the upper disc 2 covers the first surface of the grinding disc body 1 where the receiving groove is located, the upper disc 2 is in abutment with the matching layer 5 while covering the receiving groove, and a grinding pad (not shown) is fixed on the surface of the upper disc 2. In the grinding stage, the driving assembly 7 drives the transmission shaft 6 to rotate, thereby driving the grinding disc body 1 and the grinding pad fixed on the grinding disc body 1 to rotate, the grinding head drives the wafer to abut against and rotate together with the grinding pad, a polishing liquid supply arm supplies the polishing liquid to the grinding pad, and the megasonic generator 3 is turned on. Then, the megasonic generator 3 emits a megasonic wave driving signal, which is transmitted to the transducer 4 through a wire, the transducer 4 converts the megasonic wave driving signal into megasonic wave energy, drives the matching layer 5 to vibrate, thereby driving the upper disc 2 in abutment with the matching layer 5 to vibrate, the vibration of the upper disc 2 drives the vibration of the grinding pad fixed thereon, and the polishing liquid and large-particle impurities in the grinding pad pocket chamber vibrate, the polishing liquid realizes micro-flow through high-frequency vibration, and the large-particle impurities leave the grinding pad pocket chamber under the action of high-frequency vibration and micro-flow of the polishing liquid.

[0025] The grinding disc of the application is driven by megasonic waves to vibrate the grinding disc body 1 and the grinding pad fixed thereon at high frequency, the polishing liquid in the grinding pad pocket chamber vibrates at high frequency, and the polishing effect of traditional large-flow polishing liquid can be achieved under smaller flow, the utilization rate is improved, and the large-particle impurities in the grinding pad pocket chamber leave the grinding pad under the action of high-frequency vibration and micro-flow of the polishing liquid, and the wafer scratch is reduced.

[0026] As shown in Figure 1 In this embodiment, the grinding disc body 1 is a cylinder, the first surface thereof is also the bottom surface of the cylinder, and the second surface thereof is also the top surface of the cylinder. Figure 1The upper surface of the grinding disc body 1 is provided with the accommodating groove, the transducer 4 and the matching layer 5 are sequentially placed in the accommodating groove, the transducer 4 is connected with the external megasonic generator 3 through the wire, the upper disc 2 is a circular plate body matched with the cross section of the grinding disc body 1, covers the upper surface of the grinding disc body 1 and is detachably connected with the grinding disc body 1, and the grinding pad is fixed to the upper surface of the upper disc 2. The transmission shaft 6 is fixedly connected with the lower surface of the grinding disc body 1, and the driving assembly 7 can only include the motor, so that the output shaft of the motor is directly connected with the transmission shaft 6 and drives the transmission shaft 6 to rotate, or the driving assembly 7 can be provided in the transmission mode matched between the component parts, for example, the output shaft of the motor in the driving assembly 7 is fixedly connected with the shaft center of the first driving wheel, the second driving wheel is sleeved with the transmission shaft 6, and the transmission belt is sleeved between the first driving wheel and the second driving wheel, so that the motor output shaft drives the first driving wheel to rotate, the first driving wheel drives the transmission belt to rotate, the transmission belt drives the second driving wheel to rotate, and finally the second driving wheel drives the transmission shaft 6 to rotate. In the application, the megasonic auxiliary grinding disc random table grinding program is started, the machine is not started in the standby state, and can be applied to 4-inch, 6-inch, 8-inch, 12-inch or other wafer size machines. The shapes of the matching layer 5 and the transducer 4 can be, but are not limited to, symmetric geometric figures such as circles, squares, triangles and rectangles, and the materials of the matching layer 5 and the transducer 4 can be, but are not limited to, piezoelectric ceramic materials and epoxy resin materials. The matching layer 5 can select different materials and thicknesses according to different megasonic action intensity requirements, so as to ensure the highest sound transmission efficiency or lower sound transmission, and finally the megasonic action is applied to the grinding disc body 1, the upper disc 2 and the grinding pad fixed on the upper disc 2, so that the grinding pad vibrates at high frequency and small amplitude, and indirectly acts on the grinding liquid and large particle impurities in the grinding pad cell, so that the grinding liquid generates micro flow.

[0027] Optionally, the megasonic auxiliary grinding disc further comprises a grinding pad (not shown) fixedly connected with the side surface of the upper disc 2 away from the accommodating groove. The grinding pad is pre-set on the upper disc 2, which is beneficial to improve the on-site operation efficiency.

[0028] Optionally, the side surface of the grinding pad facing the upper disc 2 is provided with an adhesive layer, and the grinding pad is adhesively connected with the upper disc 2. The adhesive connection simplifies the fixed connection mode between the grinding pad and the upper disc 2, is convenient to operate and is beneficial to improve the operation efficiency.

[0029] Optionally, the megasonic-assisted polishing plate further comprises an end-point detection device (not shown) for monitoring the thickness of the film layer on the wafer surface, which is arranged in the accommodating groove. The end-point detection device is arranged to determine the thickness of the film layer on the wafer surface according to the change of the received signal, and to adjust the pressure in the sub-zone of the polishing program according to the thickness of the film layer, so as to achieve a better planarization effect, and to stop the continuous polishing when the thickness of the film layer reaches the preset thickness of the polishing program, thereby precisely controlling the polishing accuracy.

[0030] According to the actual application, the end-point detection device can adopt any commercially available end-point detection structure form that meets the monitoring requirement of the thickness of the film layer on the wafer.

[0031] Optionally, the end-point detection device comprises at least one of an optical end-point detection device and an eddy current end-point detection device. The optical end-point detection device and the eddy current end-point detection device have high sensitivity and high detection accuracy.

[0032] The accommodating groove can be provided with only one kind of end-point detection device, or can be provided with both kinds of end-point detection devices. When the detection result of any one of the end-point detection devices indicates that the thickness of the film layer on the polished wafer reaches the preset thickness, the continuous polishing is stopped. The optical end-point detection device and the eddy current end-point detection device are both mature prior art, and their specific working principles are not described herein.

[0033] Optionally, the transducer 4, the matching layer 5 and the polishing plate body 1 are coaxially arranged.

[0034] In the embodiment, the transducer 4, the matching layer 5 and the polishing plate body 1 are all arranged in a circular cross section, and are coaxially arranged with each other, and the transmission shaft 6 is coaxially arranged with them. According to the actual application, the transducer 4 and the matching layer 5 can also be arranged in other shapes different from the polishing plate body 1.

[0035] Optionally, the megasonic generator 3 generates megasonic waves with a frequency of 850 KHz-1.4 MHz. If the frequency of the megasonic waves is too low, the polishing plate body 1 cannot generate sufficient high-frequency vibration, and the polishing liquid in the polishing pad pocket chamber cannot generate sufficient high-frequency vibration, so that micro-flow cannot be achieved, the use efficiency of the polishing liquid cannot be improved, and large-particle impurities in the polishing pad pocket chamber cannot be removed under the action of high-frequency vibration and micro-flow of the polishing liquid. If the frequency of the megasonic waves is too high, higher energy is consumed, but no more beneficial technical effects can be achieved. When the frequency of the megasonic waves is arranged in the above range, the polishing plate body 1 can generate sufficient high-frequency vibration while keeping low energy consumption.

[0036] Optionally, the upper plate 2 is bolted with the polishing plate body 1. By using bolt connection, the detachable connection between the upper plate 2 and the polishing plate body 1 is simplified, and the assembly and operation are facilitated.

[0037] Optionally, the matching layer 5 is provided with an adhesive layer on the side surface facing the transducer 4, and the matching layer 5 and the transducer 4 are adhesively connected. By such arrangement, the fixed connection between the matching layer 5 and the transducer 4 is simplified, and the operation is facilitated, which is conducive to improving the assembly efficiency.

[0038] Figure 2 The schematic diagram of the polishing assembly according to an embodiment of the present application is shown in FIG. 1. As shown in the figure, the present application also provides a polishing assembly, which comprises a polishing head 8, a polishing liquid supply arm 9 and a polishing pad conditioner 10, and further comprises the megasonic-assisted polishing plate according to any one of the above embodiments. Figure 2

[0039] The megasonic-assisted polishing plate cooperates with the polishing head 8, the polishing liquid supply arm 9 and the polishing pad conditioner 10 during the polishing process. The polishing head 8 holds the wafer and provides the downforce during the polishing stage. The polishing head 8 can be fixed at a certain fixed position or can swing according to the program setting. The polishing liquid supply arm 9 delivers the polishing liquid during the polishing stage. The polishing liquid supply arm 9 can be fixed at a certain fixed position or can swing according to the program setting. The polishing pad conditioner 10 trims the polishing pad during the polishing process, increases the roughness of the polishing pad and removes the impurities generated during the polishing. This action can be implemented during the main polishing stage or before or after the polishing. Under the action of the megasonic generator 3, the transducer 4 and the matching layer 5, the upper plate 2 drives the polishing pad thereon to vibrate at high frequency, so that the polishing liquid in the polishing pad vibrates to generate micro-flow. The micro-flow of the polishing liquid increases the contact and reaction between the polishing liquid and the wafer, improves the polishing efficiency and the utilization rate of the polishing liquid, and can also improve the problem of unstable polishing rate at the edge of the wafer. The large-particle impurities generated during the polishing are vibrated in the active area of the polishing pad conditioner 10 to separate from the polishing pad cavity. Under the action of the polishing pad conditioner 10, the large-particle impurities are removed from the polishing pad and discharged with the waste liquid. At the same time, the micro-flow of the polishing liquid makes the grooves of the polishing pad not need to be widely opened, which reduces the pressure of the polishing pad conditioner 10, thereby prolonging the service life of the polishing pad and the polishing pad conditioner 10.

[0040] The following is a specific embodiment of the polishing assembly of the present application:

[0041] Embodiment 1:

[0042] ​The polishing head 8 clamps the wafer, the polishing liquid supplying arm 9 provides the polishing liquid, in the polishing process, the driving assembly 7 drives the transmission shaft 6 to rotate, providing the rotation speed for the polishing disc body 1 and the upper disc 2. In the main polishing stage, under the program setting, the polishing pad trimmer 10 starts to swing, the polishing head 8 swings at the same time, the polishing liquid supplying arm 9 is fixed at a certain position and does not move, at the same time, the megasonic generator 3 is turned on, the megasonic generator 3 emits megasonic wave with the frequency of 1.7MHz, the matching layer 5 selects the circular epoxy resin material, the transducer 4 selects the circular piezoelectric ceramic material, under the action of the megasonic wave, the center of the upper disc 2 generates the amplitude of about 7nm. The amplitude at the center of the upper disc 2 makes the polishing liquid reach the polishing rate effect of the traditional large flow under the condition of smaller flow, compared with the case without the action of the megasonic wave, the planarization effect is better.

[0043] Example 2:

[0044] The polishing head 8 clamps the wafer, the polishing liquid supplying arm 9 provides the polishing liquid, in the polishing process, the driving assembly 7 drives the transmission shaft 6 to rotate, providing the rotation speed for the polishing disc body 1 and the upper disc 2. In the main polishing stage, under the program setting, the polishing pad trimmer 10 starts to swing, the polishing head 8 and the polishing liquid supplying arm 9 swing at the same time, at the same time, the megasonic generator 3 is turned on, the megasonic generator 3 emits megasonic wave with the frequency of 1MHz, the matching layer 5 selects the elliptical aluminum material, the transducer 4 selects the elliptical piezoelectric ceramic material, under the action of the megasonic wave, the center of the upper disc 2 generates the amplitude of about 10nm. The amplitude at the center of the upper disc 2 makes the polishing liquid reach the polishing rate effect of the traditional large flow under the condition of smaller flow, compared with the case without the action of the megasonic wave, the planarization effect is better

[0045] Example 3:

[0046] The grinding head 8 clamps the wafer, the polishing liquid supply arm 9 provides the polishing liquid, in the polishing process, the driving assembly 7 drives the transmission shaft 6 to rotate, and provides the rotating speed for the polishing disc body 1 and the upper disc 2, and the eddy current end point detection device is arranged in the containing groove of the polishing disc body 1. In the main polishing stage, under the program setting, the polishing pad trimmer 10 starts to swing, the polishing liquid supply arm 9 swings at the same time, the grinding head 8 is fixed at a position and does not move, and the megasonic generator 3 is started at the same time, the megasonic generator 3 emits megasonic waves with a frequency of 1.7 MHz, the matching layer 5 is selected from circular epoxy resin materials, and the transducer 4 is selected from square piezoelectric ceramic materials, under the action of the megasonic waves, the amplitude at the center of the upper disc 2 is about 10 nm. The amplitude at the center of the upper disc 2 makes the polishing liquid reach the polishing rate effect that can be reached by the traditional large flow of polishing liquid under the condition of smaller flow, and the planarization effect is better compared with the case without the action of the megasonic waves. At the same time, the eddy current end point detection device collects the film thickness of the metal film layer wafer surface, the partition pressure of the polishing program is adjusted according to the film thickness, so that better planarization effect is achieved, and the polishing is stopped when the film thickness reaches the set value of the polishing program.

[0047] By means of the polishing assembly, the polishing disc body 1 and the polishing pad fixed thereon are driven to vibrate at high frequency by the megasonic waves, then the polishing liquid in the polishing pad groove chamber vibrates at high frequency, and the utilization rate is improved, the polishing effect that can be reached by the traditional large flow of polishing liquid can be reached under the condition of smaller flow; meanwhile, the large particles in the polishing pad groove chamber leave the polishing pad under the action of high-frequency vibration and micro-flow of the polishing liquid, and the wafer scratch is reduced; the polishing pad trimmer 10 does not need to cut the groove of the polishing pad, but only needs to cut small holes on the surface of the polishing pad, the pressure is reduced, the service life of the polishing pad and the polishing pad trimmer 10 is prolonged, and the production cost is reduced; under the assistance of the megasonic waves, the contact between the polishing liquid and the wafer is more uniform, which is beneficial to the stability of the wafer removal rate and improves the wafer flatness.

[0048] Finally, it should be noted that: the above examples are only used to illustrate the technical solutions of the present application, but not to limit them; although the present application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing examples, or make equivalent replacement for part of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A megasonically assisted lapping disk characterized by, The application relates to a megasonic-assisted polishing disc. The first surface of the polishing disc body is provided with a containing groove; The upper disc covers the first surface of the polishing disc body and is detachably connected with the polishing disc body; The megasonic generator generates megasonic waves with a frequency of 850 KHz-1.4 MHz; The transducer is arranged in the containing groove and is electrically connected with the megasonic generator; The matching layer is fixedly connected with the transducer in the containing groove and abuts against the upper disc; The transmission shaft is fixedly connected with the polishing disc body; The driving assembly is drivingly connected with the transmission shaft to drive the transmission shaft to rotate; The polishing pad is fixedly connected with the side surface of the upper disc away from the containing groove; The megasonic generator generates megasonic wave driving signals which are transmitted to the transducer through wires, the transducer converts the megasonic wave driving signals into megasonic wave energy to drive the matching layer to vibrate, thereby driving the upper disc abutting against the matching layer to vibrate, the upper disc drives the polishing pad to vibrate, and then the polishing liquid and large-particle impurities in the polishing pad chamber vibrate, the polishing liquid realizes micro-flow through high-frequency vibration, and the large-particle impurities leave the polishing pad chamber under the action of high-frequency vibration and micro-flow of the polishing liquid.

2. The megasonic-assisted polishing disc according to claim 1, wherein: The side surface of the polishing pad facing the upper disc is provided with a glue layer, and the polishing pad is glued to the upper disc.

3. The sonication-assisted milling disc of claim 1 or 2, wherein, Further comprising: An endpoint detection device for monitoring the thickness of the film layer on the wafer surface, the endpoint detection device being arranged in the containing groove.

4. The megasonic-assisted polishing disc according to claim 3, wherein: The endpoint detection device comprises at least one of an optical endpoint detection device and an eddy current endpoint detection device.

5. The megasonic-assisted polishing disc according to claim 1 or 2, wherein: The transducer, the matching layer and the polishing disc body are coaxially arranged.

6. The megasonic-assisted polishing disc according to claim 1 or 2, wherein: The upper disc is bolted to the polishing disc body.

7. The megasonic-assisted polishing disc according to claim 1 or 2, wherein: The side surface of the matching layer facing the transducer is provided with a glue layer, and the matching layer is glued to the transducer.

8. A polishing assembly comprising a polishing head, a polishing fluid supply arm, and a polishing pad conditioner, wherein, Further comprising the megasonic-assisted polishing disc according to any one of claims 1-7.

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