Polishing apparatus and method

Abstract

A polishing method for removing a film on a surface of a substrate, comprising: keeping a polishing head (4) rotating relative to a substrate (W), wherein the polishing head is provided with a polishing pad (5) facing the surface of the substrate, and the polishing pad has a size smaller than that of the surface of the substrate so as to locally polish the surface of the substrate; during polishing, film thickness distribution on the surface of the substrate is acquired at least once, and the surface of the substrate into at least two regions on the basis of the film thickness distribution acquired each time, thereby controlling a target polishing removal amount for each divided region, and polishing the at least two regions having different target polishing removal amounts until each region reaches a target film thickness. The surface of the substrate is divided on the basis of the film thickness distribution thereon, so as to control the target polishing removal amount of the polishing head for each divided region on the surface of the substrate, thereby achieving precise control of local polishing on the surface of the substrate. Further provided is a polishing apparatus.

Description

Grinding apparatus and method

[0001] This application claims priority to Chinese Patent Application No. 202510498024.2, filed on April 18, 2025, the contents of which are incorporated herein by reference in their entirety. Technical Field

[0002] This application belongs to the field of semiconductor technology and relates to a substrate polishing apparatus and polishing method. Background Technology

[0003] In the manufacturing process of semiconductor components, surface planarization is becoming increasingly important. The most important technology for surface planarization is chemical mechanical polishing (CMP). CMP supplies a polishing slurry containing abrasive particles such as silicon dioxide (SiO2) to the polishing surface of the polishing pad, and causes the substrate, which is fixed to the polishing head, to rotate synchronously with the polishing head. As a result, the substrate comes into contact with the polishing surface and slides to be polished.

[0004] A polishing head for fixing the substrate is positioned above a polishing pad. The polishing pad is larger than the substrate to be processed so that the substrate is pressed onto the polishing pad during polishing to achieve overall polishing of the substrate surface. In this polishing method, as the substrate size increases, the polishing pad also becomes larger, resulting in a large equipment footprint. Furthermore, because the polishing pad is larger than the substrate surface size, precise control of polishing in localized areas of the substrate surface is difficult. For example, during overall substrate surface polishing, the film thickness removed is often uneven due to the difficulty in individually controlling localized areas. This often results in an uneven film thickness distribution on the substrate surface, causing irregularities in the film profile. Even after using the above method to polish the entire substrate surface to remove the same thickness, the uneven film profile remains on the substrate surface.

[0005] Therefore, in view of the problems existing in the prior art, the designer of this case, based on years of experience in this industry, actively researched and improved, and thus the grinding device and method of this application came into being.

[0006] Application content

[0007] This application provides a grinding method for removing a film from the surface of a substrate, comprising:

[0008] The grinding head is kept rotating relative to the substrate, and the grinding head is equipped with a polishing pad facing the surface of the substrate. The size of the polishing pad is smaller than the size of the substrate surface to locally grind the substrate surface.

[0009] During the polishing process, the film thickness distribution on the substrate surface is acquired at least once, and the substrate surface is divided into at least two regions based on the acquired film thickness distribution each time, thereby controlling the target polishing amount for each region. The at least two regions are polished with different target polishing amounts until each region reaches the target film thickness.

[0010] Optionally, once any of the divided regions reaches the target film thickness, grinding of the region that has reached the target film thickness is stopped, or the grinding rate of the region that has reached the target film thickness is reduced to zero.

[0011] Optionally, the polishing rate can be controlled by changing at least one of the polishing conditions, including the pressure applied by the polishing head to the substrate surface, the relative rotational speed between the substrate and the polishing head, the amount of polishing slurry supplied to the substrate surface, and the horizontal movement speed of the polishing head relative to the substrate surface from the center to the edge.

[0012] Optionally, during polishing, the substrate remains stationary, the relative rotational speed between the substrate and the polishing head is the rotational speed of the polishing head, and the polishing rate is controlled by changing at least one of the pressure applied by the polishing head to the surface of the substrate and the rotational speed of the polishing head, wherein the polishing rate is positively correlated with the film thickness.

[0013] Alternatively, during the polishing process, the polishing head moves along any path on the substrate surface.

[0014] Optionally, during polishing, the polishing head moves on the substrate surface in a bow-shaped movement path.

[0015] Optionally, during the polishing process, the polishing head moves one revolution at a radial position on the substrate surface, then moves to the next radial position on the substrate surface and moves another revolution.

[0016] Optionally, during polishing, the substrate is kept rotating, and the polishing head moves in a spiral motion between the center and the edge of the substrate surface. The radial movement of the polishing head on the substrate surface remains the same for each revolution of the polishing head, and the linear velocity of the polishing head at different polishing positions on the substrate surface is made the same by changing the rotation speed of the substrate.

[0017] Optionally, during the polishing process, the rotational speed of the polishing head is kept constant, and the polishing rate is controlled by changing the pressure applied by the polishing head to the substrate surface, wherein the applied pressure is positively correlated with the film thickness.

[0018] Optionally, during polishing, the pressure applied by the polishing head to the substrate surface is kept constant, and the polishing rate is controlled by changing the polishing head rotation speed to change the relative rotation speed between the substrate and the polishing head. The polishing head rotation speed is positively correlated with the film thickness.

[0019] Optionally, before grinding the substrate surface, the method further includes: initially obtaining the substrate surface film thickness, dividing the substrate surface into initial different regions based on the initially obtained substrate surface film thickness, and controlling the target grinding amount of each divided region based on the film thickness of each initial different region before the first division of regions during the grinding process.

[0020] Optionally, the target grinding amount can be controlled by changing the dwell time at different positions on the substrate, wherein the dwell time of the grinding head at the grinding position is positively correlated with the film thickness on the substrate surface.

[0021] Optionally, as the number of times the substrate surface is divided into regions increases, the number of regions divided into regions on the substrate surface decreases.

[0022] Optionally, before grinding the substrate surface, the method further includes: removing a preset film thickness from the substrate surface using a first step, wherein the preset film thickness is greater than the remaining film thickness on the substrate surface.

[0023] Optionally, in the first step, the grinding head with a size larger than the surface of the substrate is used to contact the surface of the substrate to remove the preset film thickness, or electrochemical polishing technology is used to remove the preset film thickness.

[0024] Optionally, in the first step, a grinding head with a size smaller than the surface of the substrate is used to contact the surface of the substrate to remove the preset film thickness.

[0025] Optionally, before grinding the substrate surface, the method further includes processing the substrate by an etching process.

[0026] Optionally, dividing the substrate surface into at least two regions based on the obtained film thickness distribution includes: obtaining at least two specific regions in the circumferential and / or radial directions of the substrate based on the film thickness distribution on the substrate surface.

[0027] Optionally, during the polishing process, the film thickness distribution on the substrate surface is acquired in real time, and the polishing amount of each region is controlled in real time based on the film thickness distribution on the substrate surface.

[0028] Optionally, dividing the substrate surface into at least two regions based on the obtained film thickness distribution includes: obtaining the total film thickness difference on the substrate surface, dividing the total film thickness difference into multiple film thickness value ranges, and combining the film thickness distribution to divide regions of the substrate surface with film thickness within the same film thickness value range into the same region, so that the substrate surface is divided into at least two regions.

[0029] Optionally, during the polishing process, after the first detection of the endpoint of the substrate, the first film thickness distribution on the surface of the substrate is obtained.

[0030] Optionally, the substrate surface is divided into at least two regions based on the film thickness distribution obtained each time, so as to control the target grinding amount of each region. Specifically, the film thickness map is obtained based on the film thickness distribution, and then the film thickness map is converted into a grinding rate and grinding time map. The substrate surface is then ground according to the grinding rate and grinding time map.

[0031] Optionally, the polishing solution on the substrate surface may be removed before obtaining the film thickness distribution on the substrate surface during polishing.

[0032] To achieve the above and other related objectives, this application also provides a grinding apparatus, comprising:

[0033] A polishing table, used to hold and rotate the substrate;

[0034] The grinding head is provided with a polishing pad for contacting and pressing against the substrate to grind the substrate surface film, the size of the polishing pad being less than or equal to the size of the substrate for locally grinding the substrate surface;

[0035] A film thickness measuring instrument is used to detect the film thickness on the surface of the substrate;

[0036] The controller is configured to acquire the film thickness distribution on the substrate surface at least once during the polishing process, and to divide the substrate surface into at least two regions based on the acquired film thickness distribution each time, thereby controlling the target polishing amount for each region and polishing the at least two regions with different target polishing amounts until each region sequentially reaches the target film thickness.

[0037] Optionally, the film thickness measuring device is an optical, acoustic, or electromagnetic measuring device.

[0038] Optionally, the electromagnetic measuring device includes an eddy current measuring device.

[0039] Optionally, the substrate is quadrilateral or circular.

[0040] Optionally, the polishing table is placed horizontally with the grinding head or at an angle relative to the horizontal plane.

[0041] Optionally, the grinding head is positioned above the substrate on the polishing table.

[0042] Optionally, the grinding head is disposed below the substrate on the polishing table.

[0043] Optionally, the area of ​​the polishing pad is 1 / 10 to 2 / 3 of the area of ​​the substrate.

[0044] Optionally, an optical sensor is also included for detecting the first occurrence of an endpoint on the substrate surface.

[0045] Optionally, the film thickness measuring device moves synchronously with the grinding head in the horizontal direction.

[0046] Optionally, the film thickness measuring device is disposed on the polishing pad.

[0047] As described above, the grinding apparatus and method in this application divide the substrate surface according to the film thickness distribution on the substrate surface, thereby controlling the target grinding amount of the grinding head in each divided area on the substrate surface, and realizing precise control of local grinding of the substrate surface.

[0048] Overview of the attached figures

[0049] The features and performance of this application are further described by the following embodiments and accompanying drawings.

[0050] Figure 1 is a schematic diagram of the grinding device in one embodiment of this application.

[0051] Figure 2 is a thickness distribution diagram of the substrate surface obtained in one embodiment of this application.

[0052] Figure 3 is a schematic diagram of a specific region obtained by dividing the region in a specific manner according to an embodiment of this application.

[0053] Figure 4 is a schematic diagram of a specific area in Figure 3 being further divided into regions in a specific way.

[0054] Figure 5 is a flowchart of the CMP process performed on the substrate in the first step and the small grinding head in this application.

[0055] Figure 6 shows the grinding head moving along an arbitrary path on the substrate surface based on the substrate surface film thickness distribution map in the first embodiment of this application.

[0056] Figure 7 shows the grinding head moving on the substrate surface in a bow-shaped path in the second embodiment of this application.

[0057] Figure 8 shows the movement path of the grinding head at different radial positions on the substrate surface in the third embodiment of this application.

[0058] Figure 9(a) shows the spiral movement path of the grinding head on the substrate surface in the fourth embodiment of this application; Figure 9(b) is an enlarged view of point A in Figure 9(a).

[0059] Preferred embodiments of this application

[0060] The following specific examples illustrate the implementation of this application. Those skilled in the art can easily understand other advantages and effects of this application from the content disclosed in this specification. This application can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of this application.

[0061] In the detailed description of the embodiments of this application, for ease of explanation, the cross-sectional views illustrating the device structure may be partially enlarged and not to scale. Furthermore, the schematic diagrams are merely examples and should not limit the scope of protection of this application. In actual fabrication, the three-dimensional spatial dimensions of length, width, and depth should be included.

[0062] For ease of description, spatial relation terms such as “below,” “under,” “lower,” “below,” “below,” “above,” “upper,” and “above” may be used herein to describe the relationship between an element or feature shown in the accompanying drawings and other elements or features. It will be understood that these spatial relation terms are intended to include directions other than those depicted in the drawings for devices in use or operation. Furthermore, when a layer is referred to as being “between” two layers, it can be the only layer between the two layers, or there may be one or more layers in between. The phrase “between” as used herein includes both endpoint values.

[0063] In the context of this application, the structure described above the first feature may include embodiments in which the first and second features are formed in direct contact, or embodiments in which additional features are formed between the first and second features, such that the first and second features may not be in direct contact.

[0064] It should be noted that the illustrations provided in this embodiment are only schematic representations of the basic concept of this application. Therefore, the illustrations only show the components related to this application and are not drawn according to the actual number, shape and size of the components in the actual implementation. In the actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.

[0065] It should be noted that the polishing apparatus and method in this application can achieve localized directional polishing of the substrate surface, and can be applied to the polishing processes of copper interconnects in the damascus process and some thin-wire substrate surface films. Furthermore, in order to achieve substrate surface planarization, the polishing apparatus and method in this application act on the substrate surface to make the target film thickness the same at different locations on the substrate surface.

[0066] Referring to the embodiment in Figure 1, the polishing apparatus includes a polishing table 3 that holds and rotates the substrate W, and a polishing head 4 located above the polishing table 3. Referring to Figure 3, the polishing head 4 is equipped with a polishing pad 5 facing the substrate surface (the surface to be polished), and the size of the polishing pad 5 is less than or equal to the substrate size. In some embodiments, the area of ​​the polishing pad 5 is 1 / 10 to 2 / 3 of the substrate area, specifically determined according to the process time and accuracy requirements. The polishing table 3 and the polishing head 4 are placed horizontally simultaneously, or they can be placed at a certain angle relative to the horizontal plane. Furthermore, the polishing head 4 can be positioned above or below the substrate W; this application does not impose any limitations on this.

[0067] Polishing slurry is supplied to the substrate surface to corrode and impact the substrate surface film material as the polishing head 4 rotates relative to the substrate surface with the polishing pad 5. The polishing slurry can be supplied to the substrate surface via a supply system 7. In one example, the supply system 7 includes a polishing slurry outlet 71 for supplying polishing slurry to the substrate surface. The polishing slurry outlet 71 is connected to a polishing slurry supply source 73 via a conduit 74, and is positioned at the end of the conduit 74 to supply polishing slurry to the substrate surface. In one embodiment, the polishing slurry outlet 71 is located at the center of the polishing pad 5. At least a portion of the conduit 74 extends axially along the polishing head 4. A switching valve 72 is provided on the conduit 74, capable of opening and closing the conduit 74. A controller 2 is coupled to the switching valve 72, and by controlling the opening and closing of the switching valve 72, a metered supply of polishing slurry can be supplied to the polished surface of the substrate W at any time. After flowing through the conduit 74 to the center of the polishing pad 5, the polishing slurry flows from the polishing slurry outlet 71 to the edge of the polishing pad 5. The polishing slurry can be supplied to the substrate surface via the supply system 7. In the embodiment shown in Figure 1, at least some components of the liquid supply system 7 are integrated into the polishing head 4. In another embodiment, the liquid supply system 7 and the polishing head 4 are separate structural components. The liquid supply method of the separate liquid supply system 7 is the same as that of the integrated polishing head 4, except that the structural components are independently set. In the embodiment where the liquid supply system 7 is at least partially integrated into the polishing head 4, there is no need to set up a separate polishing liquid supply pipeline, which simplifies the equipment and makes the liquid film control between the polishing pad 5 and the substrate surface more uniform.

[0068] As shown in Figure 1, the polishing apparatus of this embodiment includes a film thickness measuring device 1 for detecting the film thickness signal on the substrate surface (the surface to be polished). The type of film thickness measuring device 1 is not limited, as long as it can obtain the film thickness signal of the substrate w. For example, the film thickness measuring device 1 can be a detector using electromagnetic, acoustic, or optical detection methods, with electromagnetic detectors including eddy current detectors. In this application, the output detected by the film thickness measuring device 1 is the film thickness or a signal equivalent to the film thickness. It should be noted that the film thickness in this application refers to the vertical thickness of the film material on the substrate surface. The position of the film thickness measuring device 1 is not limited, as long as it can measure the film thickness distribution at different positions on the substrate w. It can measure the film thickness distribution across the entire surface at once, or it can rotate a full circle to measure the film thickness at different positions separately. In one specific embodiment, as shown in Figure 1, the film thickness measuring device 1 is mounted on the arm 6 to achieve relative static positioning of the film thickness measuring device 1 and the polishing head 4 in the horizontal direction, facilitating real-time monitoring of the film thickness at different positions during the process. To better measure the film thickness at different locations on the substrate in real time during the process, the film thickness measuring device 1 can also be mounted on the polishing pad 5. This not only allows for real-time monitoring of the film thickness at different locations, but the polishing pad 5 can also squeeze out the polishing slurry from the substrate, resulting in more accurate film thickness measurements. To ensure the accuracy of the measured film thickness, the polishing slurry on the substrate is removed before each film thickness distribution measurement during polishing. For example, the substrate can be rotated to fling off the polishing slurry, or it can be cleaned with a cleaning solution.

[0069] The polishing apparatus provided in this application can solve the problem of unevenness on the entire surface of the substrate while precisely polishing. It is applicable to the polishing process of copper interconnects in damascus steel and some thin-wire substrate surface films. However, this polishing method requires a longer time to complete compared with traditional large polishing heads. The polishing apparatus and method provided in this application require a longer time to complete. Therefore, as shown in Figure 5, an electrochemical polishing (Stress Free Polish, SFP) process 110 can be performed on the substrate first. According to the total amount of polishing to be removed from the substrate, the entire surface of the substrate is subjected to the SFP process to achieve uniform thickness removal. SFP achieves 50% to 90% of the total amount of polishing on the substrate surface film, completing the rough polishing of most of the substrate surface film thickness (first step 100). Then, the polishing apparatus provided in this application is used to perform a CMP process 300 on the substrate to achieve fine polishing of the remaining amount of polishing on the substrate surface according to the film thickness distribution on the substrate surface. In some embodiments, SFP achieves 50% to 90% of the total amount of polishing on the substrate surface film, and CMP achieves the remaining part of the total amount of polishing on the substrate surface film thickness, i.e., 10% to 50%. In other specific embodiments, rough polishing (first step 100) can also be achieved using other grinding processes, such as using a CMP device with a large polishing head to achieve rough polishing process 120, where the size of the polishing pad is larger than the substrate surface size. The first step 100 removes a preset film thickness, for example, 50% to 90% of the total grinding amount mentioned above, making the preset film thickness greater than the remaining film thickness on the substrate surface. Then, the grinding apparatus and method for localized grinding described in this application are used to remove the remaining film thickness on the substrate surface. It should be noted that the size of the polishing head refers to the size of the polishing pad on the polishing head relative to the substrate surface size. For example, a large polishing head means the polishing pad on the polishing head is larger than the substrate size, and a small polishing head means the polishing pad on the polishing head is smaller than the substrate size. Since the polishing head provided in this application is smaller than the substrate size, in the first step 100, a larger polishing head among the small polishing heads provided in this application can be used to perform rough polishing of the substrate surface CMP treatment 130, for example, a polishing head with a size half that of the substrate can be used. After the first step 100 is completed, a smaller polishing head among the small polishing heads provided in this application can be used for fine polishing 300, for example, a polishing head with a size one-tenth that of the substrate can be used. In other embodiments, before polishing the substrate surface using the small polishing head provided in this application, the first step may not be as described above, but other substrate processing processes may be used, such as dry etching or wet etching processes.

[0070] Referring to Figure 1, the grinding head 4 rotates along a central axis indicated by A under the drive of a drive mechanism (not shown) to grind the substrate surface with polishing pad 5. The polishing table 3, driven by the drive mechanism (not shown), rotates with substrate W about a central axis indicated by B. In specific embodiments, during grinding, the grinding head may rotate, the substrate may rotate, or both the grinding head and the substrate may rotate together. To allow the grinding head 4 to reach any position on the substrate surface with polishing pad 5, various combinations of movements with different structures can be selectively used. For example, in addition to the substrate W rotating about the central axis indicated by B, the grinding head 4 can be selectively combined to move horizontally between the edge and center of the substrate surface along the direction indicated by C, so that the grinding head 4 and polishing pad 5 translate on the surface of substrate W. The grinding head can be driven by a drive mechanism (not shown), such as an actuator like a motor, to translate the grinding head 4 with arm 6 or to move the grinding head 4 relative to arm 6 to translate the polishing pad 5 on the surface of substrate W. The grinding head 4 can use a drive mechanism (not shown), such as an actuator like a cylinder or ball screw, to press the polishing pad 5 onto the surface of substrate W to be ground. Furthermore, for the mechanism for adjusting the pressure applied to the substrate surface, the pressure applied to the substrate W by the grinding head 4 can be adjusted by adjusting the air pressure of the cylinder, or by providing an airbag (not shown) on the back of the polishing pad 5 and using the fluid pressure supplied to the airbag to adjust the pressure applied to the substrate W by the grinding head 4. In other embodiments, an airbag can also be provided on the polishing table 3 to adjust the pressure applied to the substrate surface (the surface to be ground). The airbag is provided on the back of the substrate W (opposite to the surface to be ground), and the pressure applied to the substrate surface is adjusted by changing the air pressure in the airbag of at least one of the grinding head 4 and the polishing table 3. Since the overall thickness of the film material removed from the substrate surface using the grinding apparatus of this application is relatively thin, the change in the pressure applied to the substrate surface is small. However, the method of changing the pressure applied to the substrate surface by changing the fluid pressure in the airbag is more precise than the other methods described above. Therefore, the method of providing an airbag in at least one of the polishing table and the grinding head of the grinding apparatus to adjust the pressure applied to the substrate surface is more advantageous.

[0071] The controller 2 is also connected to the film thickness measuring device 1 to receive the signal detected by the film thickness measuring device 1. The film thickness measuring device 1 is used to detect the film thickness signal on the substrate surface. The controller 2 obtains the film thickness distribution at different positions on the substrate surface based on the film thickness signal measured by the film thickness measuring device 1. Based on the different film thickness distributions at different positions on the substrate surface, the controller 2 controls the grinding head 4 to grind the substrate surface with different target grinding amounts.

[0072] The amount of grinding can be changed by altering at least one of the grinding rate and the grinding time; preferably, the amount of grinding is changed by altering either the grinding rate or the grinding time. In some embodiments, the grinding rate is kept constant, and the amount of grinding is changed by controlling the dwell time of the grinding head at different positions. That is, in areas with thick film on the substrate surface, the dwell time of the grinding head at the grinding position is increased, and in areas with thin film on the substrate surface, the dwell time of the grinding head at the grinding position is shortened, thereby ensuring that the target amount of grinding is achieved in each area. Since the length of the process time is crucial to the process flow, in other embodiments, the dwell time of the grinding head at each grinding position is the same, and the amount of grinding is changed by controlling the grinding rate in different areas. That is, in areas with thick film on the substrate surface, the grinding rate is increased, and in areas with thin film on the substrate surface, the grinding rate is decreased, which can improve the grinding accuracy without increasing the process time.

[0073] In some embodiments, as shown in FIG6, a film thickness map of the entire substrate can be obtained after obtaining the film thickness distribution, and then the film thickness map can be converted into a grinding map according to the grinding rate and / or grinding time corresponding to each position. In this embodiment, each position of the substrate is a region, so that the substrate surface is ground according to the grinding map.

[0074] The grinding rate is positively correlated with the film thickness; that is, the thicker the film on the substrate surface, the faster the grinding head 4 grinds the substrate surface. In areas with thicker film on the substrate surface, increasing the grinding rate can improve the grinding efficiency of the substrate; while in areas with thinner film on the substrate surface, the grinding rate needs to be reduced to prevent excessive grinding due to an excessively fast grinding rate.

[0075] The grinding rate can be changed by altering one or more of the following grinding conditions: the pressure applied by the grinding head to the substrate surface, the relative rotational speed between the substrate and the grinding head, the amount of polishing slurry supplied to the substrate surface, and the horizontal movement speed of the grinding head relative to the substrate surface from the center to the edge. Since the substrate in this application can be either square or circular, when the substrate is circular, the "horizontal movement speed from the center to the edge" refers to the horizontal movement speed in the radial direction; when the substrate is square, the "horizontal movement speed from the center to the edge" refers to the horizontal movement speed in the radial direction of the circumcircle of the substrate. In this application, the controller 2 changes the grinding rate by controlling one or more of the above grinding conditions. For ease of control, the grinding rate can be changed by controlling the following movement patterns between the grinding head and the substrate, thereby precisely controlling the amount of grinding at different locations on the substrate surface:

[0076] The first method: The substrate remains stationary. In this first embodiment, the grinding head can grind the substrate surface along any path until the target grinding amount is achieved. However, the grinding rate is controlled at different grinding positions on the substrate surface by changing at least one of the pressure applied by the grinding head to the substrate surface and the rotation speed of the grinding head. Preferably, the grinding rate is controlled by changing either the pressure applied by the grinding head to the substrate surface or the rotation speed of the grinding head, so that the grinding amount is basically controlled by changing a single variable, thereby precisely controlling the grinding amount at different film thickness positions on the substrate surface. In this embodiment, when the grinding rate is controlled by changing a single variable, other conditions remain unchanged, and the single variable is positively correlated with the grinding rate. When the rotation speed of the grinding head is the only variable to be changed, the relative rotation speed between the substrate and the grinding head is changed by changing the rotation speed of the grinding head, thereby controlling the grinding rate. As shown in Figure 6, different film thicknesses are marked with different colors, and different positions T(r, α) on the substrate surface are marked with different radii and different angles. The controller controls the grinding head to move on the substrate surface along an arbitrary path, not limited to a fixed path, and controls the grinding rate based on the film thickness at different positions T(r, α) on the substrate surface.

[0077] The second method involves keeping the substrate stationary. Figure 7 shows the movement path of the grinding head in this embodiment. The grinding head moves in a zigzag pattern, alternating between horizontal and vertical directions, to grind the substrate surface. The controller can control the grinding rate by changing at least one of the following during the movement: the pressure applied by the grinding head to the substrate surface and the rotational speed of the grinding head. Preferably, the grinding rate is controlled by changing the pressure applied by the grinding head to the substrate surface and the rotational speed of the grinding head. This allows for precise control of the grinding amount at different film thickness locations on the substrate surface, essentially by changing a single variable. In this embodiment, when the grinding rate is controlled by changing a single variable, other conditions remain constant, and the single variable is positively correlated with the grinding rate. When the rotational speed of the grinding head is the only variable to be changed, the relative rotational speed between the substrate and the grinding head is altered, thereby controlling the grinding rate. Since controlling the grinding amount at the corners of a quadrilateral substrate is difficult, the method of keeping the substrate stationary and using a zigzag movement of the grinding head is well-suited for quadrilateral substrates.

[0078] The third method: The substrate remains stationary. As shown in Figure 8, the grinding head moves along its path in this embodiment. The grinding head moves one revolution at a fixed radial position A on the substrate, then moves to a different radial position B to complete another revolution. The controller can control the grinding rate by changing at least one of the following during the grinding process: the pressure applied by the grinding head to the substrate surface and the rotational speed of the grinding head. Preferably, the grinding rate is controlled by changing either the pressure applied by the grinding head to the substrate surface or the rotational speed of the grinding head. This allows the grinding rate to be controlled essentially by changing a single variable, thereby precisely controlling the amount of grinding at different film thickness positions on the substrate surface. In this embodiment, when the grinding rate is controlled by changing a single variable, other conditions remain constant, and the single variable is positively correlated with the amount of grinding. When the rotational speed of the grinding head is the only variable to be changed, the relative rotational speed between the substrate and the grinding head is changed, thereby controlling the grinding rate.

[0079] The fourth method: The substrate is kept rotating. As shown in Figure 9(a), the grinding head moves in a spiral motion between the center and the edge of the substrate surface. The grinding head maintains a constant rotation speed, while the substrate rotation speed changes to ensure that the linear velocity of the grinding head is the same at different grinding positions on the substrate surface. Furthermore, as the grinding head moves from the center to the edge of the substrate, the substrate rotation speed decreases to maintain the same linear velocity at each grinding position on the substrate surface. Simultaneously, for each revolution on the substrate surface (as shown in Figure 9(b), which is an enlarged view of point A in Figure 9(a), the radial movement d of the grinding head remains constant), under these conditions, the pressure applied by the grinding head to the substrate surface becomes essentially the sole variable controlling the grinding rate. Alternatively, the pressure applied by the grinding head to the substrate surface can remain constant, while the substrate rotation speed changes to ensure that the linear velocity of the grinding head is the same at each grinding position on the substrate surface. Furthermore, as the grinding head moves from the center to the edge of the substrate, the substrate rotation speed decreases to maintain the same linear velocity at each grinding position on the substrate surface. Simultaneously, for each revolution on the substrate surface, the radial movement d of the grinding head remains constant. Under these conditions, the rotation speed of the grinding head becomes essentially the sole variable controlling the grinding rate. In other words, under these conditions, the grinding rate is controlled by changing the relative rotation speed between the substrate and the grinding head, thereby altering the grinding head's rotation speed. The four embodiments described above are applicable to substrates of different shapes. Furthermore, in the four embodiments where the grinding amount is controlled by changing the grinding rate, a film thickness map of the entire substrate can be obtained after acquiring the film thickness distribution. This film thickness map can then be converted into a grinding rate map based on the grinding rate corresponding to each location. In this embodiment, each location on the substrate is a region, and the substrate surface is ground according to the grinding rate map. In the four embodiments where the grinding amount is controlled by changing the grinding rate, to better control the grinding rate of the substrate surface, in some embodiments, before grinding the substrate, a film thickness measuring device is used to initially acquire the film thickness of the substrate surface. Based on the initially acquired film thickness, the substrate surface is divided into initial different regions. In this embodiment, there can be two film thickness measuring devices, one for measurement before grinding and one for measurement during grinding. Preferably, the film thickness measuring device used for measurement before grinding is not integrated with the polishing pad. During grinding, before acquiring the first film thickness distribution of the substrate surface, the initial grinding rate is controlled based on the film thickness of each initial different region to grind the substrate surface. The film thickness is positively correlated with the initial grinding rate. The initial rate is also controlled by changing one or more of the following factors in the grinding conditions: the pressure applied to the substrate surface, the relative rotation speed between the substrate and the polishing pad, the amount of polishing slurry supplied to the substrate surface, and the horizontal movement speed of the grinding head relative to the substrate surface.

[0080] In this application, the target grinding amount is controlled based on the film thickness on the substrate surface. Therefore, during grinding, the film thickness measuring device acquires the film thickness distribution on the substrate surface at least once. The controller divides the substrate surface into at least two different regions according to the film thickness distribution, thereby controlling the grinding amount of each region and ensuring that each position on the substrate surface achieves precise film thickness removal. However, in some embodiments, if the substrate surface is only divided into regions once during grinding, and each region is ground with the same target grinding amount from beginning to end, insufficient grinding accuracy (e.g., errors in the machining of various parts such as the grinding head, grinding head drive mechanism, polishing table, and polishing table drive mechanism) results in each position on the substrate surface after grinding not reaching the target film thickness. Therefore, in other embodiments, during the polishing process, the film thickness distribution on the substrate surface can be acquired multiple times, and the substrate surface is divided into at least two different regions based on each acquired film thickness distribution. This allows the target polishing amount for each region to be controlled as one cycle. Each cycle yields a different film thickness profile on the substrate surface. In the next cycle, the controller re-divides the substrate surface into regions based on the film thickness profile obtained in the previous cycle and controls the target polishing amount for each region. This process continues until each region sequentially reaches its target film thickness. In this application, once any of the divided regions reaches its target film thickness, polishing of the region that has reached the target film thickness is stopped, or the polishing rate of the region that has reached the target film thickness is reduced to zero. Specifically, this can be achieved by avoiding already polished regions or by lifting the polishing pad in the already polished regions. In the other embodiments of this application, the polishing apparatus and method improve polishing accuracy by acquiring the substrate surface film thickness multiple times during polishing and continuously correcting the target polishing amount at different positions on the substrate surface. Furthermore, the more cycles in the other embodiments, the higher the polishing accuracy. Therefore, the substrate surface film thickness can be monitored in real time to acquire the substrate surface film thickness distribution in real time, and the target polishing amount for each region can be controlled in real time based on the substrate surface film thickness distribution. During substrate polishing, the polishing head polishes the substrate surface divided into regions with different polishing amounts. As the number of times the substrate surface is divided into regions increases, more and more locations on the substrate surface have reached the target film thickness and no longer need to be polished or divided into regions. Therefore, to improve polishing efficiency, the number of regions on the substrate surface can be reduced. In some embodiments, if the desired polishing accuracy is not high, the controller can acquire the substrate surface film thickness distribution only once and divide the substrate surface into at least two different regions based on the acquired substrate surface film thickness distribution, thereby controlling the target polishing amount for each region.

[0081] To achieve precise grinding at different locations on the substrate surface, in the first embodiment, the controller divides the substrate surface into multiple regions based on the currently acquired film thickness distribution and the total film thickness difference. The total film thickness difference is the difference between the maximum film thickness at different locations on the substrate surface and the target film thickness value. For example, in the exemplary embodiment shown in Figure 2, the film thickness at the highest point of the substrate surface is 1100 angstroms, and the target film thickness is 1000 angstroms, so the total film thickness difference on the substrate surface is 100 angstroms. Based on the current film thickness distribution, regions with film thicknesses within the same range are grouped into the same region, so that the substrate surface film material is removed with the same grinding amount within the same region. Continuing with the above embodiment of total film thickness difference, the total film thickness difference of 100 angstroms is divided into 10 film thickness ranges, namely 1 angstrom-10 angstroms, 11 angstroms-20 angstroms, 21 angstroms-30 angstroms, 31 angstroms-40 angstroms, 41 angstroms-50 angstroms, 51 angstroms-60 angstroms, 61 angstroms-70 angstroms, 71 angstroms-80 angstroms, 81 angstroms-90 angstroms, and 91 angstroms-100 angstroms. Based on the current film thickness distribution, the substrate surface is divided into regions according to the above multiple film thickness ranges so that the film material on the substrate surface is removed with the same amount of grinding in the same region. Under this partitioning method, the same region can be a discontinuous region on the substrate.

[0082] To achieve precise grinding at different locations on the substrate surface, in the second embodiment, the controller divides the substrate surface into regions based on the film thickness distribution along the circumferential and / or radial directions. Regions with film thicknesses within the same range are grouped into the same region, allowing the same amount of grinding material to be removed from the substrate surface within that region. For example, in the embodiment shown in Figure 3, the substrate surface is divided into regions C1 and C2 along the circumferential direction based on the film thickness distribution. Since C1 and C2 have different film thickness ranges, the grinding head applies different amounts of grinding material to them. It should be noted that other regions divided along the circumferential direction, although not shown, are also included in the regional division. To further improve the grinding accuracy of the substrate, each region is further divided into at least two grinding intervals at different radii on the substrate. Figure 4 only illustrates the radial division of region C2. Region C2 is divided into different grinding intervals C21, C22, and C23 in the radial direction based on the film thickness distribution. The grinding head applies different amounts of grinding to C21 and C22, and different amounts to C22 and C23. The method of dividing the substrate surface radially based on the film thickness distribution is similar to the method of dividing the substrate surface circumferentially based on the film thickness distribution, except that the division is changed from circumferential to radial. This will not be further elaborated. In the second embodiment, since the region is divided according to the film thickness distribution in the circumferential and / or radial directions of the substrate surface, this method of region division is a specific method, and the resulting regions are specific regions. In contrast, in the first embodiment, the region division is not based on a specific direction but only on the film thickness distribution; therefore, this method of division is a non-specific method, and the resulting regions are non-specific regions.

[0083] In the first and second embodiments described above, the range of film thickness values ​​needs to be determined based on the grinding precision; the higher the grinding precision, the smaller the difference in film thickness values. During grinding, the substrate is rotated relative to the polishing pad. The polishing pad is first positioned in a first region, the position of which is determined by the film thickness distribution on the substrate. In the first region, the grinding head grinds the substrate surface with a first grinding amount. The grinding head then moves from the first region to the second region and grinds the substrate surface with a second grinding amount. Similarly, the position of the second region is also determined by the film thickness distribution on the substrate surface, and the first and second regions on the substrate have different film thickness ranges. The grinding sequence is only an example; after dividing the regions, the grinding sequence of different regions can be determined according to process requirements. Furthermore, in the grinding method provided in this application, multiple region divisions can be performed using different division methods, or multiple region divisions can all be performed using the same method.

[0084] To improve grinding efficiency, the grinding method provided in this application does not require film thickness measurement before grinding. Instead, during grinding, the film thickness on the substrate surface is acquired only after the sensor detects the first endpoint on the substrate surface. In some embodiments, the endpoint can be detected by an optical sensor. In chemical mechanical polishing (CMP) processes, the endpoint is typically used to remove the upper film of the substrate. The upper film is usually made of a different material than the lower film; the upper film may be made of material one (e.g., copper, cobalt, ruthenium, etc.), and the lower film may be made of material two (e.g., a barrier layer, which could be cobalt, tantalum, tantalum nitride, titanium nitride, etc.). Different materials have different light reflectivities. Therefore, since the light irradiating the substrate surface will generate different reflectivities depending on the substrate surface material, the endpoint is determined by the appearance of a desired reflectivity, indicating that the substrate has reached the position where the film thickness needs to be measured. The endpoint region is usually dot-shaped, but since the sensitivity of each optical sensor varies, the size of the endpoint region is not limited by the first detection of the desired reflectivity.

[0085] In this application, the controller controls the movement of all functional components of the grinding device (polishing table, grinding head, motors, electric cylinders, air cylinders and other power units that move structural components, and the liquid supply system that starts and stops the polishing liquid supply).

[0086] The grinding apparatus and method in this application control the amount of grinding at different locations on the substrate according to the film thickness distribution on the substrate surface during the grinding process, thereby achieving precise grinding of local locations on the substrate surface.

[0087] The above embodiments are merely illustrative of the principles and effects of this application and are not intended to limit this application. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of this application. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in this application should still be covered by the claims of this application.

Claims

1. A polishing method for removing a film from the surface of a substrate, characterized in that, include: The grinding head is kept rotating relative to the substrate, and the grinding head is equipped with a polishing pad facing the surface of the substrate. The size of the polishing pad is smaller than the size of the substrate surface to locally grind the substrate surface. During the polishing process, the film thickness distribution on the substrate surface is acquired at least once, and the substrate surface is divided into at least two regions based on the acquired film thickness distribution each time, thereby controlling the target polishing amount for each region. The at least two regions are polished with different target polishing amounts until each region reaches the target film thickness.

2. The method according to claim 1, characterized in that, Once any of the divided regions reaches the target film thickness, grinding of the region that has reached the target film thickness is stopped, or the grinding rate of the region that has reached the target film thickness is reduced to zero.

3. The method according to claim 1, characterized in that, The grinding rate is controlled by changing at least one of the grinding conditions, which includes the pressure applied by the grinding head to the substrate surface, the relative rotational speed between the substrate and the grinding head, the amount of polishing slurry supplied to the substrate surface, and the horizontal movement speed of the grinding head relative to the substrate surface from the center to the edge.

4. The method according to claim 3, characterized in that, During the polishing process, the substrate remains stationary, and the relative rotational speed between the substrate and the polishing head is the rotational speed of the polishing head. The polishing rate is controlled by changing at least one of the pressure applied by the polishing head to the substrate surface and the rotational speed of the polishing head, and the polishing rate is positively correlated with the film thickness.

5. The method according to claim 4, characterized in that, During the polishing process, the polishing head moves along any path on the surface of the substrate.

6. The method according to claim 4, characterized in that, During the polishing process, the polishing head moves along a bow-shaped path on the substrate surface.

7. The method according to claim 4, characterized in that, During the polishing process, the polishing head moves one revolution at a radial position on the substrate surface, then moves to the next radial position on the substrate surface and moves another revolution.

8. The method according to claim 3, characterized in that, During grinding, the substrate is kept rotating, and the grinding head moves in a spiral motion between the center and the edge of the substrate surface. For each revolution of the grinding head on the substrate surface, the radial movement of the grinding head on the substrate surface remains the same, and the linear velocity of the grinding head at different grinding positions on the substrate surface is made the same by changing the rotation speed of the substrate.

9. The method according to claim 8, characterized in that, During the polishing process, the rotational speed of the polishing head is kept constant, and the polishing rate is controlled by changing the pressure applied by the polishing head to the substrate surface. The applied pressure is positively correlated with the film thickness.

10. The method according to claim 8, characterized in that, During the polishing process, the pressure applied by the polishing head to the substrate surface is kept constant. The polishing rate is controlled by changing the rotation speed of the polishing head to change the relative rotation speed between the substrate and the polishing head. The rotation speed of the polishing head is positively correlated with the film thickness.

11. The method according to claim 1, characterized in that, Before grinding the substrate surface, the method further includes: initially obtaining the substrate surface film thickness, dividing the substrate surface into initial different regions based on the initially obtained substrate surface film thickness, and controlling the target grinding amount of each divided region based on the film thickness of each initial different region before the first division of regions during the grinding process.

12. The method according to claim 1, characterized in that, The target grinding amount is controlled by changing the dwell time of the grinding head at different positions on the substrate, wherein the dwell time of the grinding head at the grinding position is positively correlated with the film thickness on the substrate surface.

13. The method according to claim 1, characterized in that, As the number of times the substrate surface is divided into regions increases, the number of regions divided into regions on the substrate surface decreases.

14. The method according to claim 1, characterized in that, Before grinding the substrate surface, the method further includes: removing a preset film thickness from the substrate surface using a first step, wherein the preset film thickness is greater than the remaining film thickness on the substrate surface.

15. The method according to claim 14, characterized in that, In the first step, a grinding head with a size larger than the surface of the substrate is used to contact the surface of the substrate to remove the preset film thickness, or an electrochemical polishing technique is used to remove the preset film thickness.

16. The method according to claim 14, characterized in that, In the first step, a grinding head with a size smaller than the surface of the substrate is used to contact the surface of the substrate to remove the preset film thickness.

17. The method according to claim 1, characterized in that, Before grinding the surface of the substrate, the process further includes treating the substrate by an etching process.

18. The method according to claim 1, characterized in that, Dividing the substrate surface into at least two regions based on the obtained film thickness distribution includes: obtaining at least two specific regions in the circumferential and / or radial directions of the substrate based on the film thickness distribution on the substrate surface.

19. The method according to claim 1, characterized in that, During the polishing process, the film thickness distribution on the substrate surface is acquired in real time, and the polishing amount of each region is controlled in real time based on the film thickness distribution on the substrate surface.

20. The method according to claim 1, characterized in that, Dividing the substrate surface into at least two regions based on the obtained film thickness distribution includes: obtaining the total film thickness difference on the substrate surface, dividing the total film thickness difference into multiple film thickness value ranges, and combining the film thickness distribution to divide regions of the substrate surface with film thickness within the same film thickness value range into the same region, so that the substrate surface is divided into at least two regions.

21. The method according to claim 1, characterized in that, During the polishing process, after the first detection of the endpoint of the substrate, the first film thickness distribution on the surface of the substrate is obtained.

22. The method according to claim 1, characterized in that, The substrate surface is divided into at least two regions based on the film thickness distribution obtained each time, and the target grinding amount of each region is controlled by: obtaining a film thickness map based on the obtained film thickness distribution, converting the film thickness map into a grinding rate and grinding time map, and grinding the substrate surface according to the grinding rate and grinding time map.

23. The method according to claim 1, characterized in that, Before obtaining the film thickness distribution on the substrate surface during polishing, the polishing solution on the substrate surface is removed.

24. A grinding apparatus, characterized in that, include: A polishing table, used to hold and rotate the substrate; The grinding head is provided with a polishing pad for contacting and pressing against the substrate to grind the substrate surface film, the size of the polishing pad being less than or equal to the size of the substrate for locally grinding the substrate surface; A film thickness measuring instrument is used to detect the film thickness on the surface of the substrate; The controller is configured to acquire the film thickness distribution on the substrate surface at least once during the polishing process, and to divide the substrate surface into at least two regions based on the acquired film thickness distribution each time, thereby controlling the target polishing amount for each region and polishing the at least two regions with different target polishing amounts until each region sequentially reaches the target film thickness.

25. The grinding apparatus according to claim 24, characterized in that, The film thickness measuring device is an optical, acoustic, or electromagnetic measuring device.

26. The grinding apparatus according to claim 25, characterized in that, The electromagnetic measuring device includes an eddy current measuring device.

27. The grinding apparatus according to claim 24, characterized in that, The substrate is quadrilateral or circular.

28. The grinding apparatus according to claim 24, characterized in that, The polishing table is placed horizontally with the grinding head or at a certain angle relative to the horizontal plane.

29. The grinding apparatus according to claim 24, characterized in that, The grinding head is positioned above the substrate on the polishing table.

30. The grinding apparatus according to claim 24, characterized in that, The grinding head is positioned below the substrate on the polishing table.

31. The grinding apparatus according to claim 24, characterized in that, The area of ​​the polishing pad is 1 / 10 to 2 / 3 of the area of ​​the substrate.

32. The grinding apparatus according to claim 24, characterized in that, It also includes an optical sensor for detecting the first occurrence of an endpoint on the substrate surface.

33. The grinding apparatus according to claim 24, characterized in that, The film thickness measuring device moves synchronously with the grinding head in the horizontal direction.

34. The grinding apparatus according to claim 33, characterized in that, The film thickness measuring device is mounted on the polishing pad.

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