Wafer polishing method, apparatus and device

Abstract

The application relates to the technical field of semiconductor manufacturing, and discloses a wafer grinding method, device and equipment, which comprises the following steps: adsorbing a wafer to be ground on a grinding head, the grinding head comprising a pressure film, an inner support ring and a grinding guard ring, the wafer to be ground comprising a first region, a second region and a third region arranged concentrically; performing first grinding treatment on the wafer to be ground on a first polishing pad, so that the removal amount of the first region reaches a preset removal amount; transferring the wafer to be ground after the first grinding treatment to a second polishing pad, the hardness of the second polishing pad being smaller than that of the first polishing pad; performing second grinding treatment on the wafer to be ground after the first grinding treatment on the second polishing pad, so that the thicknesses of the first region, the second region and the third region are the same, and the first lower pressure is in a normal pressure state in the process of the second grinding treatment. The application can improve the problem that the removal amount of the wafer edge is small, so that the wafer grinding surface is planarized.

Description

Technical Field

[0001] This invention relates to the field of semiconductor manufacturing technology, and specifically to a wafer grinding method, apparatus, and equipment. Background Technology

[0002] As chip manufacturing processes continue to upgrade, the requirements for wafer surface flatness and surface quality are becoming increasingly stringent. Chemical Mechanical Polishing (CMP) can more precisely control the flatness and smoothness of the wafer surface, achieving global planarization to ensure the accuracy and resolution of photolithography image transfer, thereby improving chip production efficiency and quality.

[0003] When polishing wafers using the CMP process, the downward pressure on the back of the wafer is controlled by applying different pressures to the polishing ring (RR), internal support ring (IT), and pressure film (MM). The wafer is pressed onto a rotating polishing pad, and the polishing slurry flows between the silicon wafer and the polishing pad. Under the action of the polishing pad and centrifugal force, the slurry is evenly distributed on the polishing pad. The chemical components in the polishing slurry react with the surface material of the silicon wafer, converting insoluble substances into soluble substances or softening hard substances. Through the micro-mechanical friction of the abrasive grains, these chemical reactants are removed from the surface of the silicon wafer and dissolved into the flowing liquid and carried away. Planarization is achieved through the alternation of chemical reaction and mechanical action.

[0004] However, when using the above method to grind wafers with severe bottom-over-warping (BOW) after substrate thinning, there are problems such as a small contact area between the wafer edge and the polishing pad, and a low removal rate at the edge, which leads to poor uniformity of the polished surface of the wafer and affects subsequent photolithography or etching processes. Summary of the Invention

[0005] In view of this, the present invention provides a wafer polishing method, apparatus and equipment to solve the problem of small contact area between the wafer edge and the polishing pad and low edge removal rate.

[0006] In a first aspect, the present invention provides a wafer polishing method, the method comprising: adsorbing a wafer to be polished onto a polishing head, wherein the polishing head includes a pressure film, an internal support ring, and a polishing guard ring; the wafer to be polished includes a first region, a second region, and a third region concentrically arranged; a first downward pressure of the pressure film acting on the first region; a second downward pressure of the internal support ring acting on the second region; and a third downward pressure of the polishing guard ring acting on the third region; performing a first polishing treatment on the wafer to be polished on a first polishing pad to achieve a preset removal amount in the first region; wherein, during the first polishing treatment, the first downward pressure and the first polishing time are determined according to the preset removal amount, and the second downward pressure and the third downward pressure are determined according to the first downward pressure; transferring the wafer to be polished after the first polishing treatment to a second polishing pad, wherein the hardness of the second polishing pad is less than the hardness of the first polishing pad; and performing a second polishing treatment on the wafer to be polished after the first polishing treatment on the second polishing pad to make the thickness of the first region, the second region, and the third region the same; wherein, during the second polishing treatment, the first downward pressure is at atmospheric pressure.

[0007] The wafer polishing method provided in this embodiment involves, after the wafer to be polished is adsorbed onto the polishing head, adjusting the downward pressure corresponding to three regions based on a preset removal amount. The wafer is then subjected to a first polishing treatment on a first polishing pad with higher hardness. Afterward, the wafer, having undergone the first polishing treatment, is transferred to a second polishing pad with lower hardness. While maintaining a constant initial downward pressure, the second and third downward pressures are adjusted to perform a second polishing treatment on the second polishing pad, ensuring that the thicknesses of the first, second, and third regions are equal. In this wafer polishing method, after the first polishing treatment, a second polishing pad with lower hardness is used, and the second polishing treatment is performed while maintaining a constant initial downward pressure. This results in no removal of the film material in the first region of the wafer, while increasing the removal amount in the second and third regions. This compensates for the insufficient removal amount in the second and third regions after the first polishing treatment, improving the problem of insufficient removal at the edges of the wafer and achieving surface planarization of the wafer.

[0008] In one alternative implementation, the method further includes: determining a second downward pressure, a third downward pressure, and a second grinding duration during the second grinding process based on the thickness of the first region.

[0009] The wafer polishing method provided in this embodiment determines the second downward pressure, the third downward pressure, and the second polishing time in the second polishing process based on the thickness of the first region before the second polishing process. This allows for more accurate control of the thickness of the second and third regions, ensuring that the thicknesses of the first, second, and third regions are the same.

[0010] In one alternative embodiment, the first polishing pad has a Shore hardness D of 47 to 63, and the second polishing pad has a Shore hardness C of 20 to 30.

[0011] In this embodiment, the Shore hardness D of the first polishing pad is controlled between 47 and 63, and the Shore hardness C of the second polishing pad is between 20 and 30. This can improve the polishing efficiency of the wafer while ensuring the polishing quality.

[0012] In one optional embodiment, during the first or second grinding process, the flow rate of the grinding fluid supplied by the grinding fluid supply unit is 120ml / min-180ml / min, the rotation speed of the first or second polishing pad is 93rpm-108rpm, and the rotation speed of the grinding head is 87rpm-102rpm.

[0013] In this embodiment, the flow rate of the polishing slurry supplied by the polishing slurry supply unit is controlled between 120 ml / min and 180 ml / min, the rotation speed of the first polishing pad or the second polishing pad is controlled between 93 rpm and 108 rpm, and the rotation speed of the polishing head is controlled between 87 rpm and 102 rpm. This can improve polishing efficiency while ensuring polishing quality.

[0014] In one alternative embodiment, the method further includes: pressing a polishing pad adjuster down onto the surface of a first polishing pad during a first polishing process; and pressing a polishing pad adjuster down onto the surface of a second polishing pad during a second polishing process.

[0015] In this embodiment, the polishing pad adjuster can remove the wear material on the surface of the polishing pad generated during the polishing process of the wafer to be polished, restore the internal structure of the polishing pad, maintain the surface stability of the polishing pad, and optimize the surface morphology of the polishing pad. On the other hand, it can also scrape off the waste liquid of the polishing slurry, restore the surface of the polishing pad, and keep the surface material of the wafer to be polished in good uniformity and good removal rate.

[0016] In one alternative implementation, the downward pressure applied by the polishing pad adjuster to the first polishing pad is less than or equal to 7 ibf, and the downward pressure applied by the polishing pad adjuster to the second polishing pad is less than or equal to 5 ibf.

[0017] In one alternative embodiment, before performing a first polishing process on the wafer to be polished on a first polishing pad, the method further includes: pre-flowing polishing slurry on a first polishing pad or a second polishing pad.

[0018] In this embodiment, before performing the first polishing process on the wafer to be polished, the polishing slurry is pre-flowed, which allows the polishing slurry to be evenly distributed on the first polishing pad in advance, reducing damage to the surface of the wafer to be polished during polishing and improving the surface quality of the wafer to be polished.

[0019] In one alternative embodiment, after performing a second polishing process on the wafer to be polished on the second polishing pad, which has undergone the first polishing process, the method further includes cleaning the second polishing pad.

[0020] In this embodiment, after the second grinding process, the second polishing pad is cleaned to facilitate subsequent processing.

[0021] Secondly, the present invention provides a wafer polishing apparatus, comprising: an adsorption module for adsorbing a wafer to be polished onto a polishing head, wherein the polishing head includes a concentrically arranged pressure membrane, an internal support ring, and a polishing guard ring; the wafer to be polished includes a first region, a second region, and a third region; a first downward pressure of the pressure membrane acts on the first region; a second downward pressure of the internal support ring acts on the second region; and a third downward pressure of the polishing guard ring acts on the third region; a first polishing module for performing a first polishing treatment on the wafer to be polished on a first polishing pad to achieve a preset removal amount in the first region; wherein, during the first polishing treatment, the first downward pressure and the first polishing time are determined according to the preset removal amount, and the second downward pressure and the third downward pressure are determined according to the first downward pressure; a transfer module for transferring the wafer to be polished after the first polishing treatment to a second polishing pad, wherein the hardness of the second polishing pad is less than the hardness of the first polishing pad; and a second polishing module for performing a second polishing treatment on the wafer to be polished after the first polishing treatment on the second polishing pad to make the thickness of the first region, the second region, and the third region the same; wherein, during the second polishing treatment, the first downward pressure is at atmospheric pressure.

[0022] In one alternative embodiment, the apparatus further includes: a first determining module, configured to determine a second downward pressure, a third downward pressure, and a second grinding duration during the second grinding process based on the thickness of the first region.

[0023] In one alternative embodiment, the first polishing pad has a Shore hardness D of 47 to 63, and the second polishing pad has a Shore hardness C of 20 to 30.

[0024] In one optional embodiment, during the first or second grinding process, the flow rate of the grinding fluid supplied by the grinding fluid supply unit is 120ml / min-180ml / min, the rotation speed of the first or second polishing pad is 93rpm-108rpm, and the rotation speed of the grinding head is 87rpm-102rpm.

[0025] In one optional embodiment, the apparatus further includes: a first pressing module for pressing the polishing pad adjuster down onto the surface of the first polishing pad during the first grinding process; and a second pressing module for pressing the polishing pad adjuster down onto the surface of the second polishing pad during the second grinding process.

[0026] In one alternative embodiment, the downward pressure applied by the polishing pad adjuster to the first polishing pad is less than or equal to 7 ibf, and the downward pressure applied by the polishing pad adjuster to the second polishing pad is less than or equal to 5 ibf.

[0027] In one alternative embodiment, before performing a first polishing process on the wafer to be polished on the first polishing pad, the apparatus further includes a processing module for pre-drip polishing slurry on the first polishing pad or the second polishing pad.

[0028] In one alternative embodiment, the apparatus further includes a cleaning module for cleaning the second polishing pad.

[0029] Thirdly, the present invention provides a wafer polishing apparatus, including a polishing head, a first polishing pad, a second polishing pad, and a control module; the control module is used to adsorb the wafer to be polished onto the polishing head, to perform a first polishing treatment on the wafer to be polished on the first polishing pad to achieve a preset removal amount in the first region, to transfer the wafer to be polished after the first polishing treatment to the second polishing pad, and to perform a second polishing treatment on the wafer to be polished after the first polishing treatment on the second polishing pad to make the thickness of the first region, the second region, and the third region the same. The polishing head includes a pressure diaphragm, an internal support ring, and a polishing guard ring. The wafer to be polished includes a first region, a second region, and a third region concentrically arranged. A first downward pressure of the pressure diaphragm acts on the first region, a second downward pressure of the internal support ring acts on the second region, and a third downward pressure of the polishing guard ring acts on the third region. The hardness of the second polishing pad is less than that of the first polishing pad. During the first polishing treatment, the first downward pressure and the first polishing time are determined according to the preset removal amount, and the second and third downward pressures are determined according to the first downward pressure. During the second polishing treatment, the first downward pressure is at atmospheric pressure. Attached Figure Description

[0030] To more clearly illustrate the technical solutions in the specific embodiments or related technologies of the present invention, the drawings used in the description of the specific embodiments or related technologies will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0031] Figure 1aThis is a schematic diagram of the warped wafer morphology after substrate thinning according to an embodiment of the present invention;

[0032] Figure 1b This is a schematic diagram of the state of a warped wafer after substrate thinning according to an embodiment of the present invention within a grinding head;

[0033] Figure 1c This is a schematic diagram of a wafer warped after substrate thinning according to an embodiment of the present invention on a polishing pad;

[0034] Figure 2 This is a schematic flowchart of a wafer grinding method according to an embodiment of the present invention;

[0035] Figure 3a This is a schematic diagram of the wafer to be ground being adsorbed onto the grinding head according to an embodiment of the present invention;

[0036] Figure 3b This is a schematic diagram of a grinding head according to an embodiment of the present invention;

[0037] Figure 4 This is a schematic diagram of the region location of the wafer to be ground according to an embodiment of the present invention;

[0038] Figure 5 This is a schematic flowchart of another wafer grinding method according to an embodiment of the present invention;

[0039] Figure 6 This is a schematic diagram of a wafer grinding apparatus according to an embodiment of the present invention;

[0040] Figure 7 This is a schematic diagram of the change in removal amount as a function of the second grinding time according to an embodiment of the present invention;

[0041] Figure 8 This is a schematic diagram of the horizontal axis position of the wafer to be ground according to an embodiment of the present invention;

[0042] Figure 9 This is another schematic diagram of the change in removal amount with the second grinding time according to an embodiment of the present invention;

[0043] Figure 10 This is a structural block diagram of a wafer polishing apparatus according to an embodiment of the present invention;

[0044] Figure 11 This is a structural block diagram of a wafer grinding apparatus according to an embodiment of the present invention. Detailed Implementation

[0045] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0046] With the continuous development of semiconductor technology, CMP (Chip Polishing) has become an important part of the entire chip manufacturing process. When polishing wafers using the traditional CMP process, the polishing head first brings the wafer onto the polishing pad. At the same time, the polishing guard ring (RR), internal support ring (IT), and pressure diaphragm (MM) of the polishing head control the pressure on the back of the wafer, and the wafer is polished by rotating the polishing head.

[0047] In semiconductor manufacturing, some wafers exhibit significant board-over-warping (BOW) after substrate thinning, such as... Figure 1a As shown, the wafer has a convex shape. During CMP polishing, the front side of the wafer faces down and the back side faces up. The wafer's state inside the polishing head is as follows. Figure 1b As shown, the back side of the wafer 200 to be polished is subjected to downward pressure on the polishing pad 100 for polishing, as follows: Figure 1c As shown, traditional CMP processes primarily control the surface morphology of wafers by regulating the air pressure in different areas of the polishing head to meet user requirements for wafer surface quality. However, for wafers with significant substrate bounce (BOW) after substrate thinning, the contact area between the wafer edge and the polishing pad is small, resulting in less material removal at the edge during the CMP process. Simply controlling the air pressure of the polishing head is insufficient to achieve high-standard planarization, especially at the wafer edges. This not only leads to poor uniformity of the polished surface, affecting subsequent photolithography or etching processes, but also causes chip failure in the edge area due to variations in material removal rate at the wafer edges, thereby reducing the yield of the wafer manufacturing process.

[0048] In view of this, the present invention provides a wafer grinding method that can improve the problem of insufficient removal at the wafer edge, thereby achieving planarization of the wafer surface to be processed.

[0049] According to an embodiment of the present invention, a wafer polishing method embodiment is provided. It should be noted that the steps shown in the flowchart in the accompanying drawings can be performed in a wafer polishing apparatus. Furthermore, although a logical order is shown in the flowchart, in some cases, the steps shown or described may be performed in a different order than that shown here.

[0050] This embodiment provides a wafer grinding method that can be used in a wafer grinding apparatus, wherein the wafer grinding apparatus can be a chemical mechanical polishing apparatus in the related art. Figure 2 This is a schematic flowchart of a wafer grinding method according to an embodiment of the present invention, as shown below. Figure 2 As shown, the method includes the following steps:

[0051] Step S201: Adsorb the wafer to be polished onto the polishing head.

[0052] The grinding head includes a pressure diaphragm, an internal support ring, and a grinding guard ring. The wafer to be ground includes a first region, a second region, and a third region arranged concentrically. The first downward pressure of the pressure diaphragm acts on the first region, the second downward pressure of the internal support ring acts on the second region, and the third downward pressure of the grinding guard ring acts on the third region.

[0053] For example, such as Figure 3a As shown, after the wafer 200 to be polished is adsorbed onto the polishing head 300, the polishing head 300 with the wafer 200 adsorbed is transferred onto the first polishing pad 400. That is, the wafer 200 to be polished is located between the polishing head 300 and the first polishing pad 400.

[0054] Specifically, such as Figure 3b As shown, the grinding head 300 includes a pressure diaphragm 310, an inner support ring 320, and a grinding retainer ring 330, as... Figure 4 As shown, the wafer to be polished 200 includes a first region 210, a second region 220, and a third region 230 concentrically arranged from the inside out. The first region 210 is the region on the wafer to be polished 200 corresponding to the downward pressure generated by the pressure film 310 (i.e., the first downward pressure). The second region 220 is the region on the wafer to be polished 200 corresponding to the downward pressure generated by the inner support ring 320 (i.e., the second downward pressure). The third region 230 is the region on the wafer to be polished 200 corresponding to the downward pressure generated by the polishing guard ring 330 (i.e., the third downward pressure). For example, the third region can be an edge region; for instance, the area of ​​the third region accounts for 6%-10% of the total area of ​​the surface to be polished on the wafer to be polished.

[0055] Step S202: Perform a first polishing process on the wafer to be polished on the first polishing pad so that the removal amount in the first area reaches the preset removal amount.

[0056] In the first grinding process (main grinding process), the first downward pressure and the first grinding time are determined according to the preset removal amount, and the second downward pressure and the third downward pressure are determined according to the first downward pressure.

[0057] For example, a first correspondence between the first downward pressure, the first grinding time, and the removal amount in the first region can be determined using experimental data, and a second correspondence between the first downward pressure, the second downward pressure, and the third downward pressure can be determined. Then, based on the first correspondence and the preset removal amount, the first downward pressure and the first grinding time are determined, and based on the first downward pressure and the second correspondence, the second downward pressure and the third downward pressure are determined.

[0058] The first and second correspondences are illustrated below using a table as an example, but are not limited to this. For example, taking oxide (OX) polishing as an example, the first correspondence can be shown in Table 1, and the second correspondence can be shown in Table 2. OX polishing can remove minute bumps or uneven areas on the surface of the wafer to be polished. OX polishing is merely an example in this application and is not limited to this.

[0059] Table 1

[0060]

[0061] Table 2

[0062]

[0063] For example, if the preset removal amount for a wafer of material A is 675 angstroms. Based on Table 1, the first downward pressure can be determined as 3 psi, and the first grinding time as 15 s. If the first downward pressure is determined to be 3 psi, then based on Table 2, the second downward pressure can be determined as 3.5 psi, and the third downward pressure as 6.5 psi.

[0064] Step S203: Transfer the wafer to be polished after the first polishing process to the second polishing pad.

[0065] The hardness of the second polishing pad is less than that of the first polishing pad.

[0066] Step S204: Perform a second polishing process on the wafer to be polished after the first polishing process on the second polishing pad so that the thickness of the first region, the second region and the third region are the same.

[0067] The first downward pressure is at normal pressure (i.e., standard atmospheric pressure). In other words, during the second polishing process (edge ​​polishing process), the pressure film no longer applies pressure to the first area of ​​the wafer to be polished, so that the first area has no removal or very little removal during the second polishing process.

[0068] Specifically, after the wafer to be polished undergoes a first polishing process on a harder first polishing pad, a second polishing process is performed using a softer second polishing pad, which can increase the contact area between the second and third regions of the wafer to be polished and the second polishing pad.

[0069] It should be noted that in this invention, when the thicknesses of the first region, the second region, and the third region are all preset thicknesses, the thicknesses of the first region, the second region, and the third region are considered to be the same. Similarly, when the difference in thickness between any two regions of the first region, the second region, and the third region is less than a preset difference, the thicknesses of the first region, the second region, and the third region are also considered to be the same. For example, when the thickness of the first region is... The thickness of the second region is The thickness of the third region is In this case, the thicknesses of the first, second, and third regions can be considered to be the same; the thickness of the first region is 4998 angstroms. The thickness of the second region is The thickness of the third region is In this case, the thickness of the first region, the second region, and the third region can also be considered to be the same.

[0070] The wafer polishing method provided in this embodiment involves, after the wafer to be polished is adsorbed onto the polishing head, adjusting the downward pressure corresponding to three regions based on a preset removal amount. The wafer is then subjected to a first polishing treatment on a first polishing pad with higher hardness. Afterward, the wafer, having undergone the first polishing treatment, is transferred to a second polishing pad with lower hardness. While maintaining a constant initial downward pressure, the second and third downward pressures are adjusted to perform a second polishing treatment on the second polishing pad, ensuring that the thicknesses of the first, second, and third regions are equal. In this wafer polishing method, after the first polishing treatment, a second polishing pad with lower hardness is used, and the second polishing treatment is performed while maintaining a constant initial downward pressure. This results in no removal of the film material in the first region of the wafer, while increasing the removal amount in the second and third regions. This compensates for the insufficient removal amount in the second and third regions after the first polishing treatment, improving the problem of insufficient removal at the edges of the wafer and achieving surface planarization of the wafer.

[0071] In some optional embodiments, the Shore hardness D of the first polishing pad can be any value from 47 to 63, and the Shore hardness C of the second polishing pad can be any value from 20 to 30. For example, the Shore hardness D of the first polishing pad can be 47, 50, 58, or 63, and the Shore hardness C of the second polishing pad can be 20, 22, 25, 28, or 30. In this embodiment, controlling the Shore hardness D of the first polishing pad to be between 47 and 63 and the Shore hardness C of the second polishing pad to be between 20 and 30 can improve grinding efficiency while ensuring grinding quality.

[0072] It should be understood that Shore hardness is a method for testing and representing the hardness of a material. The testing principle is to drop a specified diamond punch from a fixed height onto the surface of the sample. The punch bounces back to a certain height, and the Shore hardness is determined by the ratio of the bounce height to the drop height. D indicates that a type D (indicating) hardness tester is used for measurement, and C indicates that a visual hardness tester is used for measurement.

[0073] Specifically, the dynamic compressibility of the first polishing pad can be 0.5%-4.0%, and the dynamic compressibility of the second polishing pad can be 8.5%-20.5%. That is, the dynamic compressibility of the first polishing pad can be any value from 0.5% to 4.0%, for example, the dynamic compressibility of the first polishing pad can be 0.5%, 1.2%, 2%, 3.8%, or 4.0%. The dynamic compressibility of the second polishing pad can be any value from 8.5% to 20.5%, for example, the dynamic compressibility of the first polishing pad can be 8.5%, 9%, 12%, 15%, or 20.5%.

[0074] In the above embodiments, during the first or second grinding process, the flow rate of the grinding fluid supplied by the grinding fluid supply unit is 120ml / min-180ml / min, the rotation speed of the first or second polishing pad is 93rpm-108rpm, and the rotation speed of the grinding head is 87rpm-102rpm.

[0075] For example, the flow rate of the polishing slurry can be any value from 120 ml / min to 180 ml / min, such as 120 ml / min, 130 ml / min, 150 ml / min, 165 ml / min or 180 ml / min; the rotation speed of the first polishing pad or the second polishing pad can be any value from 93 rpm to 108 rpm, such as 93 rpm, 100 rpm, 105 rpm, 106 rpm or 108 rpm; and the rotation speed of the polishing head can be any value from 87 rpm to 102 rpm, such as 87 rpm, 90 rpm, 94 rpm, 100 rpm or 102 rpm.

[0076] In an optional embodiment, in order to improve the surface processing quality of the wafer to be polished, during the first polishing process or the second polishing process, the polishing slurry supply unit supplies polishing slurry at a flow rate of 120 ml / min, the first polishing pad or the second polishing pad rotates at 93 rpm, and the polishing head rotates at 87 rpm.

[0077] This embodiment provides a wafer grinding method, which can be used in a wafer grinding apparatus. Figure 5This is a schematic flowchart of another wafer grinding method according to an embodiment of the present invention, as shown below. Figure 5 As shown, the method includes the following steps:

[0078] Step S501: Adsorb the wafer to be polished onto the polishing head.

[0079] Please see details Figure 2 Step S201 of the illustrated embodiment will not be described again here.

[0080] Step S502: Pre-flow polishing slurry on the first polishing pad.

[0081] For example, such as Figure 6 As shown, the wafer polishing apparatus includes a polishing slurry supply unit 610, which is used to supply polishing slurry to the first polishing pad 400 on the turntable.

[0082] Specifically, before the first grinding process begins, grinding fluid is pre-flowed onto the first polishing pad; that is, before the first grinding process begins, grinding fluid is supplied to the first polishing pad through the grinding fluid supply unit 610. The pre-flowing time of the grinding fluid is a preset value, which can be determined by the operator based on experience; for example, the pre-flowing time can be 4 seconds.

[0083] In this embodiment, before performing the first polishing process on the wafer to be polished, the polishing slurry is pre-flowed, which allows the polishing slurry to be evenly distributed on the first polishing pad in advance, reducing damage to the surface of the wafer to be polished during polishing and improving the surface quality of the wafer to be polished.

[0084] Step S503: During the first grinding process, the polishing pad adjuster is pressed down onto the surface of the first polishing pad.

[0085] Specifically, such as Figure 6 As shown, the wafer polishing apparatus also includes a polishing pad adjuster 620, which is used to apply downward pressure to the polishing pad (first polishing pad or second polishing pad) on the turntable and to perform adjustment or cleaning actions on the maintained downward pressure on the polishing pad surface.

[0086] For example, the downward pressure applied to the first polishing pad by the polishing pad adjuster is less than a first preset pressure value, wherein the first preset pressure value can be determined by the operator based on experience, for example, the first preset pressure value can be 7 ibf.

[0087] In this embodiment, the polishing pad adjuster can remove the wear material on the surface of the polishing pad generated during the polishing process of the wafer to be polished, restore the internal structure of the polishing pad, maintain the surface stability of the polishing pad, and optimize the surface morphology of the polishing pad. On the other hand, it can also scrape off the waste liquid of the polishing slurry, restore the surface of the polishing pad, and keep the surface material of the wafer to be polished in good non-uniformity and good removal rate.

[0088] Step S504: Perform a first polishing process on the wafer to be polished on the first polishing pad so that the removal amount in the first area reaches the preset removal amount.

[0089] Please see details Figure 2 Step S202 of the illustrated embodiment will not be described again here. Step S505: Transfer the wafer to be polished after the first polishing treatment to the second polishing pad.

[0090] Please see details Figure 2 Step S203 of the illustrated embodiment will not be described again here.

[0091] In some optional embodiments, after performing a first polishing process on the wafer to be polished on the first polishing pad, the first polishing pad is cleaned, and after cleaning the first polishing pad, step S505 is executed. In this embodiment, the cleaning method and cleaning time are not limited. For example, cleaning can be performed by chemical solution, deionized water, or ion beam cleaning, and the cleaning time can be 5s, 10s, or 12s, etc.

[0092] In this embodiment, before transferring the wafer to be ground after the first grinding process to the second polishing pad, the first polishing pad is cleaned to remove impurities from the surface of the wafer to be ground, thus avoiding affecting the second grinding process and improving the processing quality of the wafer surface.

[0093] Step S506: During the second polishing process, the polishing pad adjuster is pressed down onto the surface of the second polishing pad.

[0094] For example, the downward pressure applied to the second polishing pad by the polishing pad adjuster is less than a second preset pressure value, wherein the second preset pressure value can be determined by the operator based on experience, for example, the second preset pressure value can be 5 ibf.

[0095] In an optional embodiment, before performing a second polishing process on the wafer to be polished after the first polishing process, polishing slurry is pre-flowed onto the second polishing pad through the polishing slurry supply unit, so that the polishing slurry is evenly distributed on the second polishing pad in advance, thereby reducing damage to the surface of the wafer to be polished during polishing and improving the surface quality of the wafer to be polished.

[0096] Step S507: Based on the thickness of the first region, determine the second downward pressure, the third downward pressure, and the second grinding time during the second grinding process.

[0097] Specifically, after determining the thickness of the first region, and assuming that the thicknesses of the first, second, and third regions are the same, the removal amounts of the second and third regions during the second grinding process can be determined. Then, based on a third correspondence, the second downward pressure, the third downward pressure, and the second grinding time during the second grinding process can be determined. The third correspondence is the relationship between the second downward pressure, the third downward pressure, the second grinding time, and the removal amounts of the second and third regions, and can be determined through experimental data.

[0098] For example, by setting the first pressure to a normal pressure (vent) state, and by adjusting the second pressure, the third pressure, and the second grinding time, the removal amount of the second and third regions under different combinations of the second pressure, the third pressure, and the second grinding time can be obtained, thereby obtaining the third correspondence.

[0099] For example, as shown in Table 3, under the conditions of a third pressure of 6.5 psi, a second pressure of 4 psi, and a first pressure of atmospheric pressure, the removal amount of the second and third regions can be determined through experiments at different second grinding times.

[0100] Table 3

[0101]

[0102] Table 3 shows the average removal amounts in the second and third regions, corresponding to the change curves of the removal amount on the wafer surface under the second polishing time. Figure 7 As shown, Figure 7 The horizontal axis x in the diagram represents the wafer to be ground along the horizontal diameter direction (e.g., ...). Figure 8 The coordinates of the coordinates are shown in the figure, with the vertical axis y representing the amount removed at the corresponding coordinate position. According to... Figure 7 As shown in Table 3, it can be seen that under the same second and third downward pressures, the amount of material removed from the edge of the wafer to be ground changes significantly with the increase of the second grinding time. Therefore, the wafer grinding method provided by this invention can effectively improve the problems of low grinding rate in the wafer edge region and incomplete grinding at the edge.

[0103] For example, as shown in Table 4, under conditions of a third downward pressure of 8 psi, a second downward pressure of 6 psi, and a first downward pressure of atmospheric pressure, the removal amounts in the second and third regions can be determined experimentally for different second polishing times. The removal amounts in the second and third regions shown in Table 4 are the average removal amounts for the second and third regions. The curves showing the change in removal amount on the wafer surface under the corresponding second polishing time can be seen as follows: Figure 9 As shown, Figure 9 The horizontal axis x in the diagram represents the wafer to be ground along the horizontal diameter direction (e.g., ...). Figure 8 The coordinates are shown in the figure, with the vertical axis y representing the amount removed at the corresponding coordinate point.

[0104] Table 4

[0105]

[0106] According to Table 4 and Figure 9 As shown, under the same second and third downward pressures, the amount of material removed from the edge of the wafer to be ground changes significantly with the increase of the second grinding time. Furthermore, a comparison of Tables 3 and 4 shows that increasing the second grinding time or increasing the second and third downward pressures can increase the amount of material removed.

[0107] Step S508: Perform a second polishing process on the wafer to be polished after the first polishing process on the second polishing pad so that the thickness of the first region, the second region and the third region are the same.

[0108] Please see details Figure 2 Step S204 of the illustrated embodiment will not be described again here.

[0109] Step S509: Clean the second polishing pad.

[0110] Specifically, after the second grinding process, the second polishing pad is cleaned to facilitate subsequent processing. In this embodiment, the cleaning time and method are not limited; the cleaning time can be determined by the operator based on experience, for example, 11 seconds, and the cleaning method can be chemical solution cleaning, deionized water cleaning, or ion beam cleaning, etc.

[0111] The wafer polishing method provided in this embodiment determines the second downward pressure, the third downward pressure, and the second polishing time in the second polishing process based on the thickness of the first region before the second polishing process. This allows for more accurate control of the thickness of the second and third regions, ensuring that the thicknesses of the first, second, and third regions are the same.

[0112] In this embodiment, a wafer polishing apparatus is also provided, which is used to implement the above embodiments and preferred embodiments; details already described will not be repeated. As used below, the term "module" can refer to a combination of software and / or hardware that implements a predetermined function. Although the apparatus described in the following embodiments is preferably implemented in software, hardware implementation, or a combination of software and hardware, is also possible and contemplated.

[0113] This embodiment provides a wafer grinding apparatus, such as Figure 10 As shown, it includes:

[0114] The adsorption module 1001 is used to adsorb the wafer to be polished onto the polishing head. The polishing head includes a pressure diaphragm, an internal support ring, and a polishing guard ring arranged concentrically. The wafer to be polished includes a first region, a second region, and a third region. The first downward pressure of the pressure diaphragm acts on the first region, the second downward pressure of the internal support ring acts on the second region, and the third downward pressure of the polishing guard ring acts on the third region.

[0115] The first grinding module 1002 is used to perform a first grinding process on the wafer to be ground on the first polishing pad so that the removal amount of the first region reaches a preset removal amount. In the first grinding process, the first downward pressure and the first grinding time are determined according to the preset removal amount, and the second downward pressure and the third downward pressure are determined according to the first downward pressure.

[0116] The transfer module 1003 is used to transfer the wafer to be polished after the first polishing treatment to the second polishing pad, wherein the hardness of the second polishing pad is less than that of the first polishing pad.

[0117] The second grinding module 1004 is used to perform a second grinding process on the wafer to be ground after the first grinding process on the second polishing pad, so that the thickness of the first region, the second region and the third region are the same. During the second grinding process, the first downward pressure is at atmospheric pressure.

[0118] In some alternative embodiments, the apparatus further includes:

[0119] The first determining module is used to determine the second downward pressure, the third downward pressure, and the second grinding time during the second grinding process based on the thickness of the first region.

[0120] In some alternative embodiments, the first polishing pad has a Shore hardness D of 47 to 63, and the second polishing pad has a Shore hardness C of 20 to 30.

[0121] In some optional embodiments, during the first or second grinding process, the flow rate of the grinding fluid supplied by the grinding fluid supply unit is 120 ml / min-180 ml / min, the rotation speed of the first or second polishing pad is 93 rpm-108 rpm, and the rotation speed of the grinding head is 87 rpm-102 rpm.

[0122] In some alternative embodiments, the apparatus further includes:

[0123] The first pressing module is used to press the polishing pad adjuster down onto the surface of the first polishing pad during the first grinding process.

[0124] The second pressing module is used to press the polishing pad adjuster down onto the surface of the second polishing pad during the second grinding process.

[0125] In some alternative implementations, the downward pressure applied by the polishing pad adjuster to the first polishing pad is less than or equal to 7 ibf, and the downward pressure applied by the polishing pad adjuster to the second polishing pad is less than or equal to 5 ibf.

[0126] In some alternative embodiments, before performing a first polishing process on the wafer to be polished on the first polishing pad, the apparatus further includes:

[0127] A processing module for pre-flowing polishing fluid on a first polishing pad or a second polishing pad.

[0128] In some alternative embodiments, the apparatus further includes:

[0129] The cleaning module is used to clean the second polishing pad.

[0130] Further functional descriptions of the above modules and units are the same as those in the corresponding embodiments described above, and will not be repeated here.

[0131] In this embodiment, the wafer polishing apparatus is presented in the form of a functional unit. Here, a unit refers to an application-specific integrated circuit (ASIC), a processor and memory that execute one or more software or fixed programs, and / or other devices that can provide the above functions.

[0132] This invention also provides a wafer grinding apparatus, such as... Figure 11 As shown, the wafer polishing equipment includes a polishing head 300, a first polishing pad 400, a second polishing pad 500, and a control module 600.

[0133] Specifically, the control module 600 is used to adsorb the wafer to be polished onto the polishing head, to perform a first polishing treatment on the wafer to be polished on a first polishing pad to achieve a preset removal amount in the first region, to transfer the wafer to be polished after the first polishing treatment to a second polishing pad, and to perform a second polishing treatment on the wafer to be polished on the second polishing pad to make the thickness of the first region, the second region, and the third region the same. The polishing head includes a pressure diaphragm, an internal support ring, and a polishing guard ring. The wafer to be polished includes a first region, a second region, and a third region concentrically arranged. The pressure diaphragm applies a first downward pressure to the first region, the internal support ring applies a second downward pressure to the second region, and the polishing guard ring applies a third downward pressure to the third region. The hardness of the second polishing pad is less than that of the first polishing pad. During the first polishing treatment, the first downward pressure and the first polishing time are determined according to the preset removal amount, and the second and third downward pressures are determined according to the first downward pressure. During the second polishing treatment, the first downward pressure is at atmospheric pressure.

[0134] For example, the control module 600 may be a computer device, server, or processor, etc.

[0135] Although embodiments of the invention have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the invention, and such modifications and variations all fall within the scope defined by the appended claims.

Claims

1. A wafer grinding method, characterized in that, The method includes: A wafer to be polished is adsorbed onto a polishing head, wherein the wafer to be polished is warped. The polishing head includes a pressure diaphragm, an internal support ring, and a polishing guard ring. The wafer to be polished includes a first region, a second region, and a third region arranged concentrically. The first downward pressure of the pressure diaphragm acts on the first region, the second downward pressure of the internal support ring acts on the second region, and the third downward pressure of the polishing guard ring acts on the third region. The wafer to be polished is subjected to a first polishing process on a first polishing pad so that the removal amount in the first region reaches a preset removal amount. During the first polishing process, the first downward pressure and the first polishing time are determined according to the preset removal amount, and the second downward pressure and the third downward pressure are determined according to the first downward pressure. The wafer to be ground, after undergoing the first grinding process, is transferred to a second polishing pad, wherein the hardness of the second polishing pad is less than that of the first polishing pad, so as to increase the contact area between the second region and the second polishing pad and the contact area between the third region and the second polishing pad. Based on the thickness of the first region, the second downward pressure, the third downward pressure, and the second grinding time are determined during the second grinding process. A second polishing process is performed on the wafer to be polished on the second polishing pad after the first polishing process, so that the thickness of the first region, the second region and the third region are the same, wherein the first downward pressure is at normal pressure during the second polishing process.

2. The method according to claim 1, characterized in that, The first polishing pad has a Shore hardness of 47 to 63, and the second polishing pad has a Shore hardness of 20 to 30.

3. The method according to claim 1, characterized in that, During the first or second grinding process, the flow rate of the grinding fluid supplied by the grinding fluid supply unit is 120ml / min-180ml / min, the rotation speed of the first or second polishing pad is 93rpm-108rpm, and the rotation speed of the grinding head is 87rpm-102rpm.

4. The method according to any one of claims 1 to 3, characterized in that, The method further includes: During the first grinding process, the polishing pad adjuster is pressed down onto the surface of the first polishing pad; During the second polishing process, the polishing pad adjuster is pressed down onto the surface of the second polishing pad.

5. The method according to claim 4, characterized in that, The downward pressure applied by the polishing pad adjuster to the first polishing pad is less than or equal to 7 ibf, and the downward pressure applied by the polishing pad adjuster to the second polishing pad is less than or equal to 5 ibf.

6. The method according to any one of claims 1 to 3, characterized in that, Before performing the first polishing process on the wafer to be polished on the first polishing pad, the method further includes: Pre-flow polishing fluid onto the first polishing pad or the second polishing pad.

7. The method according to any one of claims 1 to 3, characterized in that, After performing a second polishing process on the wafer to be polished on the second polishing pad, which has undergone the first polishing process, the method further includes: The second polishing pad is then cleaned.

8. The method according to claim 1, characterized in that, The method is implemented using a wafer polishing apparatus, which includes: An adsorption module is used to adsorb the wafer to be polished onto a polishing head, wherein the wafer to be polished is warped, the polishing head includes a concentrically arranged pressure diaphragm, an internal support ring and a polishing guard ring, the wafer to be polished includes a first region, a second region and a third region, the first downward pressure of the pressure diaphragm acts on the first region, the second downward pressure of the internal support ring acts on the second region, and the third downward pressure of the polishing guard ring acts on the third region; A first grinding module is used to perform a first grinding process on the wafer to be ground on a first polishing pad so that the removal amount in the first region reaches a preset removal amount. During the first grinding process, the first downward pressure and the first grinding time are determined according to the preset removal amount, and the second downward pressure and the third downward pressure are determined according to the first downward pressure. A transfer module is used to transfer the wafer to be polished after the first polishing treatment to a second polishing pad, wherein the hardness of the second polishing pad is less than that of the first polishing pad, so as to increase the contact area between the second region and the second polishing pad and increase the contact area between the third region and the second polishing pad. The first determining module is used to determine the second downward pressure, the third downward pressure, and the second grinding time during the second grinding process based on the thickness of the first region. The second grinding module is used to perform a second grinding process on the wafer to be ground, which has undergone the first grinding process, on the second polishing pad, so that the thickness of the first region, the second region and the third region are the same, wherein the first downward pressure is at normal pressure during the second grinding process.

9. The method according to claim 1, characterized in that, The method is implemented using a wafer polishing equipment, which includes a polishing head, a first polishing pad, a second polishing pad, and a control module. The control module is configured to: adsorb the wafer to be polished onto the polishing head; perform a first polishing process on the wafer to be polished on the first polishing pad to achieve a preset removal amount in the first region; transfer the wafer to be polished after the first polishing process onto the second polishing pad; determine the second downward pressure, the third downward pressure, and the second polishing time during the second polishing process based on the thickness of the first region; and perform a second polishing process on the wafer to be polished on the second polishing pad to achieve the same thickness in the first, second, and third regions. The wafer to be polished exhibits warping. The polishing head includes a pressure diaphragm, an internal support ring, and a polishing guard ring. The wafer grinding process includes a first region, a second region, and a third region arranged concentrically. The first downward pressure of the pressure film acts on the first region, the second downward pressure of the internal support ring acts on the second region, and the third downward pressure of the grinding guard ring acts on the third region. The hardness of the second polishing pad is less than that of the first polishing pad to increase the contact area between the second region and the second polishing pad, and to increase the contact area between the third region and the second polishing pad. During the first grinding process, the first downward pressure and the first grinding time are determined according to the preset removal amount, and the second downward pressure and the third downward pressure are determined according to the first downward pressure. During the second grinding process, the first downward pressure is at atmospheric pressure.

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