Method and device for double-sided CMP of wafer, and storage medium

Abstract

A method and device for double-sided CMP of a wafer, and a storage medium. The method comprises: determining one or more sets of polishing parameters on the basis of monitoring indexes during a polishing process; and on the basis of the one or more sets of polishing parameters, polishing a wafer to be processed. By means of monitoring and adjusting polishing parameters, polishing processing can improve a polishing effect.

Description

A method, apparatus and storage medium for double-sided CMP polishing of wafers Technical Field

[0001] This specification relates to the field of wafer polishing technology, and in particular to a method, apparatus and storage medium for double-sided CMP polishing of wafers. Background Technology

[0002] In semiconductor manufacturing technology, surface planarization is a crucial technique for high-density photolithography. This is because a flat, smooth surface on a wafer is essential to prevent scattering during exposure, enabling precise pattern transfer. Chemical Mechanical Polishing (CMP) is a widely used technique for material removal and surface planarization. In CMP, a polishing slurry is supplied to the wafer. The oxidizing agent in the slurry lightly etches the material layer on the wafer surface, forming a thin oxide layer. Subsequently, a polishing pad mechanically removes this oxide layer, achieving the desired wafer polishing. However, the distribution of the polishing slurry on the wafer is often uncontrollable during polishing. Uneven distribution results in an uneven surface after polishing, negatively impacting the polishing effect. Summary of the Invention

[0003] One embodiment of this specification provides a method for double-sided CMP polishing of a wafer, comprising: determining one or more sets of polishing parameters based on monitoring indicators during the polishing process; and polishing the wafer to be processed based on the one or more sets of polishing parameters.

[0004] In some embodiments, determining one or more sets of polishing parameters based on monitoring indicators during polishing includes: obtaining initial polishing parameters; polishing the wafer to be processed based on the initial polishing parameters; obtaining the monitoring indicators during the polishing process; and adjusting the initial polishing parameters based on the monitoring indicators to obtain the one or more sets of polishing parameters.

[0005] In some embodiments, the polishing parameters include the valve opening of a plurality of polishing slurry supply ports, and the monitoring index includes the uniformity of polishing slurry distribution, which is represented by the flow distribution of a plurality of polishing slurry recovery ports; the plurality of polishing slurry supply ports are used to supply polishing slurry to different regions of the wafer to be processed, and the plurality of polishing slurry recovery ports are used to discharge at least a portion of the used polishing slurry from positions corresponding to different regions of the wafer to be processed.

[0006] In some embodiments, the polishing parameters further include polishing pressure and polishing speed.

[0007] In some embodiments, adjusting the initial polishing parameters based on the monitoring indicators includes: generating a plurality of candidate polishing parameters based on the monitoring indicators in response to the monitoring indicators meeting preset conditions; predicting the polishing effect of the plurality of candidate polishing parameters; and determining the adjusted initial polishing parameters based on the polishing effect of the plurality of candidate polishing parameters.

[0008] In some embodiments, the wafer to be processed is a SiC wafer, and the polishing effect includes at least one of the C-side polishing effect, the Si-side polishing effect, and the combined polishing effect, wherein the combined polishing effect is determined based on the C-side polishing effect and the Si-side polishing effect.

[0009] In some embodiments, before generating multiple candidate polishing parameters based on the monitoring indicators, the method further includes: determining the influence factors of various parameters in the initial polishing parameters; and determining the unit change value of each type of parameter based on the influence factors of the various parameters.

[0010] In some embodiments, generating multiple candidate polishing parameters based on the monitoring indicators includes: determining the variation range of the various parameters based on the difference between the monitoring indicators and the preset conditions, and the influence factors of the various parameters; and generating the candidate polishing parameters based on the variation range of the various parameters and the unit change value of the various parameters.

[0011] In some embodiments, predicting the polishing effect of the plurality of candidate polishing parameters includes: predicting the polishing effect of the candidate polishing parameters based on the candidate polishing parameters and the monitoring indicators, wherein the effect prediction model is a machine learning model.

[0012] In some embodiments, the input data of the effect prediction model further includes a sequence of crystal powder content stored in the polishing slurry recovery device, wherein the sequence of crystal powder content includes the crystal powder content in the used polishing slurry corresponding to time points distributed according to preset time intervals within a preset historical time period.

[0013] In some embodiments, the method further includes: determining whether the growth rate of the crystal powder is abnormal based on the sequence of the crystal powder content; and adjusting the current polishing parameters and issuing a warning message in response to the abnormal growth rate of the crystal powder.

[0014] In some embodiments, adjusting the initial polishing parameters based on the monitoring indicators includes: generating a plurality of candidate polishing parameters based on the monitoring indicators in response to the monitoring indicators meeting preset conditions; predicting the polishing effect of the plurality of candidate polishing parameters; predicting the polishing risk of the plurality of candidate polishing parameters; and determining the adjusted initial polishing parameters based on the polishing risk and the polishing effect of the plurality of candidate polishing parameters.

[0015] In some embodiments, predicting the polishing risk of the plurality of candidate polishing parameters includes: predicting the polishing risk of the candidate polishing parameters based on the candidate polishing parameters and the monitoring indicators, wherein the risk prediction model is a machine learning model; predicting the polishing effect of the plurality of candidate polishing parameters includes: predicting the polishing effect of the candidate polishing parameters based on the candidate polishing parameters and the monitoring indicators, wherein the effect prediction model is a machine learning model.

[0016] In some embodiments, the effect prediction model and the risk prediction model are obtained through joint training.

[0017] Some embodiments of this specification also provide a computer-readable storage medium storing computer instructions that, when at least a portion of the computer instructions are executed by a processor, enable the wafer double-sided CMP polishing method as described in any embodiment of this specification.

[0018] Some embodiments of this specification also provide an apparatus for double-sided CMP polishing of a wafer, comprising: a polishing disc and a workpiece fixture, the polishing disc including a first polishing disc and a second polishing disc disposed opposite to each other, the workpiece fixture being used to hold a wafer to be processed between the first polishing disc and the second polishing disc; a polishing slurry delivery system configured to deliver polishing slurry to the polishing disc and / or the wafer to be processed; and a frame for carrying the polishing disc and the polishing slurry delivery system.

[0019] In some embodiments, the polishing slurry delivery system includes a plurality of polishing slurry supply ports and a plurality of polishing slurry recovery ports, wherein the plurality of polishing slurry supply ports are arranged corresponding to different positions of the polishing disc, and the plurality of polishing slurry recovery ports are arranged corresponding to different positions of the polishing disc; each of the plurality of polishing slurry supply ports is provided with a valve, and each of the plurality of polishing slurry recovery ports is provided with a flow meter.

[0020] In some embodiments, the polishing disc is equipped with a pressure sensor and / or a temperature sensor.

[0021] In some embodiments, the apparatus further includes a polishing slurry recovery device configured to store used polishing slurry.

[0022] In some embodiments, the apparatus further includes an optical device configured to detect the crystal powder content in the polishing slurry recovery device. Attached Figure Description

[0023] This specification will be further described by way of exemplary embodiments, which will be described in detail with reference to the accompanying drawings. These embodiments are not limiting; in these embodiments, the same reference numerals denote the same structures, wherein:

[0024] Figure 1 is an exemplary flowchart of a method for double-sided CMP polishing of a wafer according to some embodiments of this specification;

[0025] Figure 2 is an exemplary flowchart of a method for determining one or more sets of polishing parameters according to some embodiments of this specification;

[0026] Figure 3 is an exemplary flowchart illustrating the adjustment of initial polishing parameters according to some embodiments of this specification;

[0027] Figure 4 is another exemplary flowchart illustrating the adjustment of initial polishing parameters according to some embodiments of this specification;

[0028] Figure 5 is an exemplary frame diagram of an apparatus for double-sided CMP polishing of wafers according to some embodiments of this specification. Detailed Implementation

[0029] To more clearly illustrate the technical solutions of the embodiments in this specification, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are merely some examples or embodiments of this specification. For those skilled in the art, these drawings can be applied to other similar scenarios without creative effort. Unless obvious from the context or otherwise specified, the same reference numerals in the drawings represent the same structures or operations.

[0030] It should be understood that the terms “system,” “device,” “unit,” and / or “module” used herein are one way to distinguish different components, elements, parts, sections, or assemblies at different levels. However, if other terms can achieve the same purpose, they may be replaced by other expressions.

[0031] As indicated in this specification and claims, unless the context clearly indicates otherwise, the words "a," "an," "an," and / or "the" do not specifically refer to the singular and may also include the plural. Generally speaking, the terms "comprising" and "including" only indicate the inclusion of expressly identified steps and elements, which do not constitute an exclusive list, and the method or apparatus may also include other steps or elements.

[0032] Figure 1 is an exemplary flowchart of a method for double-sided CMP polishing of a wafer according to some embodiments of this specification. As shown in Figure 1, process 100 may include:

[0033] Step 110: Based on monitoring indicators during the polishing process, determine one or more sets of polishing parameters. In some embodiments, step 110 may be performed by a processor.

[0034] In some embodiments, during the polishing process, the polishing apparatus (e.g., polishing apparatus 500 hereinafter referred to as polishing apparatus 500) can provide polishing slurry to different areas of the wafer to be processed. After the polishing slurry acts on the surface of the wafer to be processed, it is discharged from a location corresponding to the different areas of the wafer to be processed. In some embodiments, the polishing apparatus may include a plurality of polishing slurry supply ports and a plurality of polishing slurry recovery ports. The plurality of polishing slurry supply ports are used to provide polishing slurry to different areas of the wafer to be processed, respectively, and the plurality of polishing slurry recovery ports are used to discharge at least a portion of the used polishing slurry from a location corresponding to the different areas of the wafer to be processed, respectively.

[0035] A wafer to be processed refers to a wafer or a group of wafers to be polished. A wafer to be processed may include one or more wafers to be polished. In some embodiments, different regions of a wafer to be processed may be different regions on a single wafer to be polished. In some embodiments, different regions of a wafer to be processed may also be different regions of a group of wafers consisting of multiple wafers to be polished.

[0036] In some embodiments, the plurality of polishing slurry supply ports can be used to provide polishing slurry to different wafers in the wafers to be processed. For example, each polishing slurry supply port is used to provide polishing slurry to a corresponding wafer in the wafers to be processed. In this case, one polishing slurry supply port corresponds to one wafer to be polished. As another example, each polishing slurry supply port is used to provide polishing slurry to at least a portion of the wafers in the wafers to be processed. In this case, one polishing slurry supply port corresponds to multiple wafers to be polished. In some embodiments, at least a portion of the plurality of polishing slurry supply ports can be used to provide polishing slurry to one wafer in the wafers to be processed. For example, at least a portion of the plurality of polishing slurry supply ports are used to provide polishing slurry to different regions of the same wafer. In this case, the plurality of polishing slurry supply ports correspond to one wafer to be polished.

[0037] In some embodiments, the plurality of polishing slurry recovery ports can be used to discharge at least a portion of the used polishing slurry from different wafers corresponding to the wafers to be processed. For example, one polishing slurry recovery port corresponds to one wafer to be polished, and each polishing slurry recovery port is used to discharge at least a portion of the used polishing slurry from the corresponding wafer. As another example, one polishing slurry recovery port corresponds to multiple wafers to be polished, and each polishing slurry recovery port is used to discharge at least a portion of the used polishing slurry from the corresponding multiple wafers. In some embodiments, at least a portion of the plurality of polishing slurry recovery ports can be used to discharge at least a portion of the used polishing slurry from different locations within the same wafer. In this case, the plurality of polishing slurry recovery ports correspond to one wafer to be polished.

[0038] In some embodiments, the number of multiple polishing slurry supply ports and multiple polishing slurry return ports may be the same. For example, there may be a one-to-one correspondence between the polishing slurry supply ports and the polishing slurry return ports; after the polishing slurry supplied by the polishing slurry supply port acts on the wafer to be processed, that portion of the polishing slurry is discharged through the polishing slurry return port corresponding to the polishing slurry supply port. In some embodiments, the number of multiple polishing slurry supply ports and multiple polishing slurry return ports may be different. For example, at least a portion of the multiple polishing slurry supply ports may correspond to one polishing slurry return port; after the polishing slurry supplied by at least a portion of the multiple polishing slurry supply ports acts on the wafer to be processed, that portion of the polishing slurry is discharged through one polishing slurry return port. As another example, one polishing slurry supply port may correspond to at least a portion of the multiple polishing slurry return ports; after the polishing slurry supplied by one polishing slurry supply port acts on the wafer to be processed, that portion of the polishing slurry is discharged through different polishing slurry return ports.

[0039] In some embodiments, at least a portion of the used polishing slurry can be recycled through a polishing slurry recovery port (e.g., collected in a polishing slurry recovery device through the polishing slurry recovery port), while the remaining portion of the used polishing slurry is not recycled but stored in some grooves of the polishing device. The unrecycled polishing slurry is then supplied to the wafer to be processed again during the next polishing.

[0040] Monitoring indicators refer to metrics that can affect the polishing effect during the polishing process. In some embodiments, monitoring indicators may include the uniformity of polishing slurry distribution. The uniformity of polishing slurry distribution refers to the uniformity of the polishing slurry distribution on the surface of the wafer to be processed. The uniformity of polishing slurry distribution can be represented by the flow distribution of multiple polishing slurry return ports.

[0041] In some embodiments, the flow distribution of multiple polishing slurry recovery ports can reflect the uniformity of polishing slurry distribution on the wafer to be processed. The flow distribution of multiple polishing slurry recovery ports refers to the ratio of polishing slurry flow through each port. In some embodiments, polishing slurry is supplied to different areas of the wafer to be processed through multiple polishing slurry supply ports, and the polishing slurry may be uniformly or non-uniformly distributed on the wafer. When the polishing slurry is uniformly distributed, the used polishing slurry is discharged through multiple polishing slurry recovery ports, and there is a proportional distribution among the flow rates of the polishing slurry flowing through the multiple recovery ports; this proportional distribution is the standard flow ratio. In other words, when the ratio among the flow rates of the polishing slurry flowing through the multiple recovery ports is (or close to) the standard flow ratio, it can be considered that the polishing slurry is uniformly distributed on the wafer to be processed. When the polishing slurry is non-uniformly distributed, the used polishing slurry is discharged through multiple recovery ports, and the proportional distribution among the flow rates of the polishing slurry flowing through the multiple recovery ports differs significantly from the standard flow ratio. In other words, when the ratio of polishing fluid flow rates through multiple polishing fluid recovery ports differs significantly from the standard flow rate ratio, it can be considered that the polishing fluid is unevenly distributed on the wafer to be processed.

[0042] In some embodiments, the standard flow ratio can be obtained through historical experience or experimentation.

[0043] Polishing parameters refer to the parameters of relevant components during polishing. These components may include polishing slurry supply ports, polishing discs, etc. In some embodiments, polishing parameters may include the valve openings of multiple polishing slurry supply ports. Valve opening is a parameter that controls the flow rate of polishing slurry through the supply ports. A larger valve opening results in a larger flow rate of polishing slurry per unit time; a smaller valve opening results in a smaller flow rate. In some embodiments, the valve opening of the polishing slurry supply ports can affect the uniformity of polishing slurry distribution on the wafer to be processed, thereby affecting the polishing effect. The uniformity of polishing slurry distribution affects the polishing effect as follows: When the polishing slurry is uniformly distributed on the wafer to be processed, the oxidant in the slurry corrodes the material layer on different parts of the wafer surface to a basically uniform degree. That is, the surface of the wafer is uniformly corroded to form an oxide layer. Subsequently, the oxide is mechanically ground to remove it, which can improve the flatness and uniformity of the wafer surface after polishing. Conversely, when the polishing slurry is unevenly distributed on the wafer to be processed, the oxidant in the slurry corrodes the material layer on different parts of the wafer surface to a large degree. When the oxide is mechanically ground to remove it from the wafer surface, it will result in an uneven wafer surface.

[0044] In some embodiments, polishing parameters may further include polishing pressure and polishing rotation speed. Polishing pressure refers to the pressure applied by the polishing pad to the wafer to be processed during the polishing process. Polishing rotation speed refers to the speed at which the polishing pad rotates about its own axis during the polishing process.

[0045] During the polishing process, the wafer to be processed is held between polishing pads (e.g., a first polishing pad and a second polishing pad). The polishing pads apply polishing pressure to the wafer while rotating at a polishing speed. During rotation, the pressure applied by the polishing pads to the wafer is converted into friction, and the polishing pads mechanically grind the surface of the wafer, thereby removing oxides and achieving wafer polishing. Based on the above process, it is clear that polishing pressure and polishing speed can affect the polishing effect. For example, the higher the polishing pressure and / or polishing speed, the stronger the mechanical action of the polishing pads on the surface of the wafer, the shorter the time required to complete the polishing process, and the higher the polishing efficiency. However, excessive polishing pressure and / or polishing speed may cause wafer damage (e.g., excessive polishing pressure may crack the wafer; excessive polishing pressure may cause scratches on the wafer surface; excessive polishing speed requires a longer time for the polishing pads to stop rotating, and during the deceleration process, unnecessary mechanical grinding may be performed on the already polished wafer, resulting in scratches on the wafer surface). The lower the polishing pressure and / or polishing speed, the weaker the mechanical action of the polishing pad on the surface of the wafer to be processed, the longer the polishing process takes, and the lower the polishing efficiency.

[0046] In some embodiments, the polishing pressure and polishing speed can be determined according to the polishing process requirements. Polishing process requirements include, but are not limited to, the material layer thickness of the wafer to be processed and the material of the wafer to be processed. The material of the wafer to be processed includes, but is not limited to, silicon carbide, silicon dioxide, aluminum, copper, tungsten, etc. As an example, when the material layer thickness of the wafer to be processed is large, the polishing pressure can be set to a larger value and the polishing speed to a faster value; when the material layer thickness of the wafer to be processed is small, the polishing pressure can be set to a smaller value and the polishing speed to a slower value.

[0047] In some embodiments, polishing parameters can be determined using a lookup table. In some embodiments, one or more sets of polishing parameters can be determined using a feature index parameter table based on monitoring indicators during the polishing process. In some embodiments, the feature index parameter table may include different monitoring indicators obtained during the polishing process and a preset correspondence between the corresponding polishing parameters. In some embodiments, the feature index parameter table can be obtained experimentally. For example, based on the monitoring indicators obtained during the polishing process, various different polishing parameters are selected for experiments, and the polishing effect corresponding to each polishing parameter (such as the flatness of the wafer surface, whether there are scratches, etc.) is evaluated. Polishing parameters with better polishing effects are selected, a preset correspondence between monitoring indicators and polishing parameters is established, and a feature index parameter table is generated.

[0048] In some embodiments, one or more sets of polishing parameters can be determined based on initial polishing parameters. In some embodiments, one or more sets of polishing parameters can be determined by adjusting the initial polishing parameters. In some embodiments, multiple initial polishing parameters can be obtained in advance, and then adjusted one or more times based on monitoring indicators during the polishing process. The adjusted initial polishing parameters are then used as the determined set of one or more sets of polishing parameters. For more details on the method for determining one or more sets of polishing parameters based on initial polishing parameters, please refer to Figure 2 and its related description.

[0049] Step 120: Polish the wafer to be processed based on one or more sets of polishing parameters. In some embodiments, step 120 may be performed by an apparatus for double-sided CMP polishing of wafers (e.g., polishing apparatus 500 described below).

[0050] In some embodiments, the set or more polishing parameters determined in step 110 can be sent to an apparatus for double-sided CMP polishing of wafers (e.g., polishing apparatus 500 hereinafter), which performs double-sided polishing of the wafer to be processed based on the polishing parameters. The polishing parameters may include, but are not limited to, one or more of the following: valve opening of multiple polishing slurry supply ports, polishing pressure, polishing rotation speed, etc. In some embodiments, the apparatus for double-sided CMP polishing of wafers may include polishing pads, a workpiece fixture, and a polishing slurry delivery system. The polishing pads include a first polishing pad and a second polishing pad disposed opposite each other, and the workpiece fixture is used to hold the wafer to be processed between the first polishing pad and the second polishing pad. The polishing slurry delivery system is configured to deliver polishing slurry to the polishing pads and / or the wafer to be processed through multiple polishing slurry supply ports. The polishing process is as follows: A workpiece fixture holds the wafer to be processed between a first polishing pad and a second polishing pad, with the first and second polishing pads respectively in contact with the two surfaces of the wafer. A polishing slurry delivery system supplies polishing slurry to the polishing pads and / or different areas of the wafer through multiple slurry supply ports, wherein the valve openings of the multiple slurry supply ports are the valve openings determined in step 110. The polishing pads rotate at a polishing speed while simultaneously applying polishing pressure to the wafer to polish it, wherein the polishing speed and polishing pressure are the speed and pressure determined in step 110. During this process, after the polishing slurry is delivered to different areas of the wafer surface, the oxidant in the polishing slurry corrodes the material layer on both surfaces of the wafer to form an oxide layer. As the first and second polishing pads rotate, the two polishing pads mechanically grind away the oxides on the two surfaces of the wafer. Thus, the wafer can be polished through the combined action of chemical and mechanical processes.

[0051] The embodiments in this specification, by determining reasonable polishing parameters, such as the valve openings of multiple polishing slurry supply ports, can ensure that the polishing slurry is evenly distributed on the surface of the wafer to be processed. This results in a more uniform degree of corrosion of the oxidant in the polishing slurry on different parts of the wafer surface, thereby improving the polishing effect, such as increasing the flatness and uniformity of the polished wafer surface. Furthermore, by reasonably setting the valve openings of multiple polishing slurry supply ports, the utilization efficiency of the polishing slurry can also be improved.

[0052] It should be noted that the above description of process 100 is for illustrative purposes only and does not limit the scope of this specification. Those skilled in the art can make various modifications and changes to process 100 under the guidance of this specification. However, these modifications and changes remain within the scope of this specification.

[0053] Figure 2 is an exemplary flowchart of a method for determining one or more sets of polishing parameters according to some embodiments of this specification. As shown in Figure 2, process 200 may include:

[0054] Step 210: Obtain initial polishing parameters. In some embodiments, step 210 may be performed by a processor.

[0055] The initial polishing parameters may include one or more sets of polishing parameters that the polishing apparatus can execute sequentially. In some embodiments, the initial polishing parameters may be pre-stored in the polishing apparatus (e.g., memory), and the processor directly retrieves the initial polishing parameters from the polishing apparatus. In some embodiments, the initial polishing parameters may be determined experimentally or based on historical experience, and are pre-stored in the memory of the polishing apparatus.

[0056] Step 220: Polish the wafer to be processed based on the initial polishing parameters. In some embodiments, step 220 may be performed by a polishing apparatus.

[0057] In some embodiments, the polishing apparatus can polish the wafer to be processed based on initial polishing parameters. These initial polishing parameters may include, but are not limited to, one or more of the following: initial valve openings of multiple polishing slurry supply ports, initial polishing pressure, and initial polishing rotation speed. The polishing process is as follows: After the wafer to be processed is placed, the polishing slurry delivery system delivers polishing slurry to the polishing pad and / or different areas of the wafer to be processed through multiple polishing slurry supply ports, wherein the valve openings of the multiple polishing slurry supply ports are the valve openings in the initial polishing parameters obtained in step 210; the polishing pad rotates at a polishing rotation speed while simultaneously applying polishing pressure to the wafer to be processed to polish it, wherein the polishing rotation speed and polishing pressure are the rotation speed and pressure in the initial polishing parameters obtained in step 210.

[0058] Step 230: Obtain monitoring indicators during the polishing process. In some embodiments, step 230 may be executed by a processor.

[0059] In some embodiments, when polishing a wafer to be processed based on initial polishing parameters, parameters of the monitored target can be acquired during the polishing process. For example, the uniformity of the polishing slurry distribution can be acquired during polishing. In some embodiments, during polishing, the flow rate of multiple polishing slurry recovery ports can be collected using sensors (such as flow meters). The flow rate of the multiple polishing slurry recovery ports collected by the sensors is transmitted to a processor. The processor analyzes and processes the flow rate of the multiple polishing slurry recovery ports to determine the flow rate distribution of the multiple polishing slurry recovery ports. Furthermore, the processor determines the uniformity of the polishing slurry distribution during the polishing process based on the flow rate distribution of the multiple polishing slurry recovery ports. For ease of understanding and description, the flow rate distribution of the multiple polishing slurry recovery ports acquired by sensors (such as flow meters) is called the current flow rate ratio. In some embodiments, the uniformity of the polishing slurry distribution can be determined based on the difference between the standard flow rate ratio and the current flow rate ratio. For example, the smaller the sum of the absolute values ​​of the differences between the standard flow rate ratio and the current flow rate ratio, the higher the uniformity of the polishing slurry distribution; the larger the sum of the absolute values ​​of the differences between the standard flow rate ratio and the current flow rate ratio, the lower the uniformity of the polishing slurry distribution. The sum of the absolute values ​​of the differences between the standard flow ratio and the current flow ratio refers to the sum of the absolute values ​​of the differences in the flow rate of polishing fluid flowing through each of the multiple polishing fluid recovery ports. For example, if the standard flow ratio is 1:2:3:2:1 and the current flow ratio is 1:3:3:3:2, then the absolute value of the difference between the standard flow ratio and the current flow ratio is |1-1| : |2-3| : |3-3| : |2-3| : |1-2|, which is 0:1:0:1:1; the sum of the absolute values ​​of the differences between the standard flow ratio and the current flow ratio is 0+1+0+1+1=3.

[0060] In some embodiments, a flow ratio difference threshold can be set. When the sum of the absolute values ​​of the differences between the standard flow ratio and the current flow ratio is less than the flow ratio difference threshold, the polishing fluid is determined to be uniformly distributed. When the sum of the absolute values ​​of the differences between the standard flow ratio and the current flow ratio is greater than the flow ratio difference threshold, the polishing fluid is determined to be unevenly distributed.

[0061] In some embodiments, multiple flow ratio difference thresholds can be set to determine the uniformity of the polishing slurry distribution. For example, a first difference threshold, a second difference threshold, and a third difference threshold can be set. The first difference threshold < the second difference threshold < the third difference threshold. When the absolute value of the difference between the standard flow ratio and the current flow ratio is less than the first difference threshold, the uniformity of the polishing slurry distribution is determined to be high; when the absolute value of the difference between the standard flow ratio and the current flow ratio is greater than the first difference threshold and less than the second difference threshold, the uniformity of the polishing slurry distribution is determined to be medium; when the absolute value of the difference between the standard flow ratio and the current flow ratio is greater than the second difference threshold and less than the third difference threshold, the uniformity of the polishing slurry distribution is determined to be low; when the absolute value of the difference between the standard flow ratio and the current flow ratio is greater than the third difference threshold, the polishing slurry is determined to be unevenly distributed.

[0062] In some embodiments, the flow ratio difference threshold can be set according to actual needs (such as polishing effect requirements), and this specification does not further limit it.

[0063] It is understandable that the determination of the uniformity of polishing fluid distribution based on the difference between the standard flow ratio and the current flow ratio is made from an overall perspective (that is, by considering the flow rates of multiple polishing fluid recovery ports). This approach can improve the processor's processing efficiency.

[0064] In some embodiments, the flow rate of each of the multiple polishing slurry recovery ports can be compared with the corresponding standard flow rate to determine the uniformity of the polishing slurry distribution. For example, each of the multiple polishing slurry recovery ports has a standard flow rate (the flow rate of polishing slurry through each recovery port when the polishing slurry is uniformly distributed). During polishing, a sensor (such as a flow meter) is used to acquire the current flow rate of each of the multiple polishing slurry recovery ports. The standard flow rate of the same recovery port is compared with the current flow rate to determine the uniformity of the polishing slurry distribution. As an example, a flow difference threshold can be set. If the absolute value of the difference between the standard flow rate and the current flow rate of each recovery port is less than the flow difference threshold, the polishing slurry can be judged to be uniformly distributed; if the absolute value of the difference between the standard flow rate and the current flow rate of any recovery port is greater than the flow difference threshold, the polishing slurry can be judged to be unevenly distributed. In this embodiment, it is necessary to determine whether the flow rate of each polishing slurry recovery port is reasonable to determine whether the polishing slurry is uniformly distributed, which can improve the accuracy of the judgment. In some embodiments, the flow difference threshold can be a percentage of the standard flow, such as 0.1%, 0.5%, 1%, 2%, 5%, 10%, 20% of the standard flow, etc. The flow difference threshold can be set according to actual needs (such as polishing effect requirements), and this specification does not further limit it.

[0065] Step 240: Based on the monitoring indicators, adjust the initial polishing parameters to obtain one or more sets of polishing parameters. In some embodiments, step 240 may be executed by a processor.

[0066] In some embodiments, if the monitoring indicators obtained in step 230 meet the requirements, that is, when the polishing fluid is uniformly distributed, the current initial polishing parameters can be used as one or more sets of polishing parameters.

[0067] In some embodiments, if the monitoring indicators obtained in step 230 do not meet the requirements, i.e., the polishing fluid is unevenly distributed, it is necessary to adjust the initial polishing parameters, such as adjusting the valve opening of at least some of the multiple polishing fluid supply ports. In some embodiments, when the absolute value of the difference between the current flow rate and the standard flow rate of a certain polishing fluid recovery port is greater than the flow difference threshold, the valve opening of the polishing fluid supply port corresponding to that polishing fluid recovery port can be adjusted. As an example, the error value e(t) between the current flow rate and the standard flow rate of the polishing fluid recovery port can be calculated first, and then the valve opening of the polishing fluid supply port corresponding to that polishing fluid recovery port can be calculated according to kp*e(t)+ki*e(t)+kd*e(t). Wherein, kp is the proportional gain coefficient, reflecting the direct influence of the flow error on the valve opening adjustment, ki is the integral gain coefficient, reflecting the long-term influence of the error accumulation on the valve opening, and kd is the differential gain coefficient, reflecting the instantaneous adjustment of the valve opening by the flow rate change. In some embodiments, kp, ki, and kd can be determined by experimental methods or automatic adjustment methods (such as the Ziegler-Nichols method).

[0068] For each of the multiple polishing fluid recovery ports, if the absolute value of the difference between the current flow rate and the standard flow rate of the polishing fluid recovery port is greater than the flow difference threshold, the valve opening of the corresponding polishing fluid supply port can be adjusted in the above manner. The adjusted valve openings of the multiple polishing fluid supply ports can then be used as one or more sets of polishing parameters.

[0069] Understandably, the process of adjusting the initial polishing parameters can be done in one go or iteratively until the adjusted polishing parameters meet the requirements.

[0070] The embodiments in this specification adjust the valve opening of the corresponding polishing fluid supply port based on the error value between the current flow rate of the polishing fluid recovery port and the standard flow rate, which can improve the accuracy of valve opening adjustment.

[0071] It should be noted that the above description of process 200 is for illustrative purposes only and does not limit the scope of this specification. Those skilled in the art can make various modifications and changes to process 200 under the guidance of this specification. However, these modifications and changes remain within the scope of this specification.

[0072] In some embodiments, the initial polishing parameters can be adjusted based on the polishing effect. Figure 3 is an exemplary flowchart of adjusting the initial polishing parameters according to some embodiments of this specification. As shown in Figure 3, process 300 may include the following steps:

[0073] Step 310: In response to the monitoring indicators meeting preset conditions, multiple candidate polishing parameters are generated based on the monitoring indicators. In some embodiments, step 310 may be executed by a processor.

[0074] Preset conditions refer to the conditions that must be met before the initial polishing parameters can be adjusted. For example, if the polishing slurry distribution is uneven or the polishing pressure / speed is unreasonable, the polishing parameters need to be adjusted. Preset conditions may include one or more of the following: uneven polishing slurry distribution, unreasonable polishing pressure / speed.

[0075] Candidate polishing parameters can include multiple sets of different polishing parameters that the polishing device can execute sequentially.

[0076] In some embodiments, after adjusting the initial polishing parameters based on monitoring indicators to obtain adjusted initial polishing parameters, one of multiple polishing slurry supply ports can be selected, and noise can be added to the valve opening of that polishing slurry supply port to obtain a candidate polishing parameter. Here, a candidate polishing parameter refers to the combination of the valve opening with added noise and the valve opening without added noise. Taking a port with three polishing slurry supply ports as an example, the initial valve opening of the first polishing slurry supply port is 2, the initial valve opening of the second polishing slurry supply port is 3, and the initial valve opening of the third polishing slurry supply port is 1. The initial polishing parameters are [2, 3, 1]. After adding noise to the initial valve opening of the second polishing slurry supply port, the valve opening of the second polishing slurry supply port becomes 2.8, while the valve openings of the first and third polishing slurry supply ports remain unchanged. The candidate polishing parameter obtained after adding noise is [2, 2.8, 1]. Similarly, one polishing slurry supply port can be selected multiple times to add noise, obtaining corresponding candidate polishing parameters each time, thus forming multiple sets of candidate polishing parameters. In some embodiments, the polishing slurry supply port can be selected randomly.

[0077] Step 320: Predict the polishing effect of multiple candidate polishing parameters. In some embodiments, step 320 may be executed by a processor.

[0078] Polishing results can indicate the quality of a polished wafer. For example, polishing results can include the smoothness of the wafer surface, the presence of scratches on the wafer surface, and the uniformity of wafer thickness.

[0079] In some embodiments, when the wafer to be processed is a SiC wafer, the polishing effect includes at least one of the following: C-side polishing effect, Si-side polishing effect, and comprehensive polishing effect. The comprehensive polishing effect is determined based on the C-side polishing effect and the Si-side polishing effect. In some embodiments, the comprehensive polishing effect can be a weighted effect of the C-side polishing effect and the Si-side polishing effect, wherein the weights of the C-side polishing effect and the Si-side polishing effect can be preset. In some embodiments, the weights of the C-side polishing effect and the Si-side polishing effect can be reasonably preset according to the emphasis on the polishing effect. For example, when emphasizing the C-side polishing effect, the weight of the C-side polishing effect can be set to be greater than the weight of the Si-side polishing effect. Similarly, when emphasizing the Si-side polishing effect, the weight of the Si-side polishing effect can be set to be greater than the weight of the C-side polishing effect. Furthermore, when the C-side polishing effect and the Si-side polishing effect are equal, the weight of the Si-side polishing effect can be set to be equal to the weight of the C-side polishing effect.

[0080] In some embodiments, the polishing effect of the candidate polishing parameters can be predicted using an effect prediction model based on the candidate polishing parameters and monitoring indicators. In some embodiments, the effect prediction model includes a first machine learning model.

[0081] The input data for the first machine learning model consists of candidate polishing parameters and monitoring metrics. The output data is the polishing effect of the corresponding candidate polishing parameters. In some embodiments, the first machine learning model can be obtained by training a first initial machine learning model based on a large number of first training samples with first training labels. The first training samples may include candidate polishing parameters and monitoring metrics, as well as the polishing effect corresponding to the candidate polishing parameters, wherein the polishing effect corresponding to the candidate polishing parameters is the first training label. Specifically, the labeled first training samples can be input into the first initial machine learning model to obtain the output result of the first initial machine learning model. The parameters of the first initial machine learning model are updated through training until the trained first intermediate machine learning model meets a first preset condition, thereby obtaining a trained first machine learning model. The first preset condition may be that the loss function reflecting the difference between the output result of the first machine learning model and the first training label is less than a preset threshold, the loss function converges, or the number of training iterations reaches a preset threshold.

[0082] In some embodiments, the first training samples and labels can be obtained through various means such as historical data, networks, and human experience.

[0083] In some embodiments, the input data of the first machine learning model may further include information about the wafer to be processed and information about the polishing equipment. The wafer to be processed information may include the material (e.g., silicon carbide, silicon dioxide, aluminum, copper, tungsten, etc.) and thickness of the wafer. The polishing equipment information may include polishing pad information (e.g., polishing pad size, material of the polishing pad on the polishing pad for contact with the wafer to be processed) and other information (e.g., type of polishing equipment, maintenance records, etc.). By also including the wafer to be processed information and the polishing equipment information as input data to the first machine learning model, the polishing effect can be predicted more accurately.

[0084] In some embodiments, the first machine learning model can also predict the polishing effect of corresponding candidate polishing parameters based on the crystal powder content in the polishing slurry recovery device. The polishing slurry recovery device is a device for storing used polishing slurry. At least a portion of the used polishing slurry flows through multiple polishing slurry recovery ports into the polishing slurry recovery device for storage.

[0085] In some embodiments, over-polishing may occur during the polishing process. For example, polishing may not only remove the oxides on the wafer surface but also slightly grind the wafer itself, resulting in a small amount of crystal powder remaining in the used polishing slurry. The crystal powder content in the used polishing slurry reflects the degree of over-polishing. A higher crystal powder content indicates a higher degree of over-polishing, while a lower content indicates a lower degree. When the crystal powder content in the used polishing slurry is too high, abnormalities may occur during the polishing process.

[0086] In some embodiments, the input data of the first machine learning model may further include a sequence of crystal powder content, which may include the crystal powder content in the polishing slurry corresponding to time points distributed according to preset time intervals within a preset historical period. For example, the sequence of crystal powder content is [P]. t1 P t2 , ..., P tn 】, where t1, t2, ..., tn represent polishing time points that have occurred within a preset historical time period, and P represents the content of crystal powder in the polishing slurry corresponding to that polishing time point. In some embodiments, the content of crystal powder can be expressed as concentration.

[0087] By also using the sequence of crystal powder content as input data for the first machine learning model, the accuracy of the first machine learning model in predicting polishing effects can be improved.

[0088] In some embodiments, the growth rate of the crystal powder can reflect whether there is an abnormality in the polishing process. For example, a sudden change or continuous increase in the growth rate of the crystal powder may indicate an abnormality in the polishing process (e.g., over-polishing, excessive polishing pressure, etc.). The growth rate of the crystal powder can be the amount of crystal powder growth within a preset time interval. For example, the sequence of crystal powder content is [P]. t1 P t2 , ..., P tn At time t1 to t2, the growth rate of the crystal powder is (P) t2 -P t1 ) / (t2-t1).

[0089] In some embodiments, the growth rate of the crystal powder can be determined based on the sequence of crystal powder content; in response to an abnormal growth rate of the crystal powder, the current polishing parameters are adjusted and a warning message is issued.

[0090] In some embodiments, a speed growth threshold range can be set. When the growth rate of the crystal powder is outside this range, it indicates an abnormality in the growth rate. In this case, the current polishing parameters need to be adjusted and a warning message issued. In some embodiments, in response to an abnormal crystal powder growth rate, the current polishing parameters can be adjusted to default values. These default values ​​can be pre-set, safe polishing parameters. For example, default values ​​(such as polishing pressure, polishing speed, and the valve opening of the polishing fluid supply) can be set relatively low. Under these default values, polishing efficiency may be lower, but the polishing process can be guaranteed to proceed without abnormalities. In some embodiments, in response to an abnormal crystal powder growth rate, the polishing device can be switched to standby mode or shut down. In some embodiments, in response to an abnormal crystal powder growth rate, the polishing device can issue a warning message, such as a voice alert, a horn alarm, or a flashing indicator light.

[0091] By detecting whether the growth rate of the crystal powder is abnormal and issuing timely warnings, the polishing process can be monitored, thereby ensuring the safety of the wafer during polishing.

[0092] Step 330: Based on the polishing effects of multiple candidate polishing parameters, determine the adjusted initial polishing parameters. In some embodiments, step 330 may be executed by a processor.

[0093] In some embodiments, after predicting the polishing effect of each candidate polishing parameter using an effect prediction model, the candidate polishing parameter with better polishing effect can be determined as the adjusted initial polishing parameter.

[0094] It should be noted that the above description of process 300 is for illustrative purposes only and does not limit the scope of this specification. Those skilled in the art can make various modifications and changes to process 300 under the guidance of this specification. However, these modifications and changes remain within the scope of this specification.

[0095] In some embodiments, before generating multiple candidate polishing parameters (i.e. before step 310), the processor may first determine the influence factors of various parameters in the initial polishing parameters; and then, based on the influence factors of various parameters, determine the unit change value of various parameters.

[0096] Polishing parameters can include things like the valve opening at the polishing slurry supply, polishing pressure, and polishing speed. Each type of parameter has a different degree of influence on the polishing effect. An influence factor can characterize the magnitude of a parameter's influence on the polishing effect. For example, the larger the influence factor of a certain type of polishing parameter, the greater its influence on the polishing effect; conversely, the smaller the influence factor, the smaller its influence on the polishing effect.

[0097] In some embodiments, multivariate analysis can be used to determine the influencing factors of various parameters. Multivariate analysis methods include, but are not limited to, PCA, CA, MRA, FA, etc.

[0098] In some embodiments, the unit change value of various parameters can be determined by looking up a table. The unit change value of a parameter refers to the amount of change in the parameter value per unit time. In some embodiments, the unit change value of a parameter can be the maximum allowable change value for a single parameter change. In some embodiments, the unit change value of various parameters can be determined based on the influence factors of various parameters through a parameter correspondence table. In some embodiments, the parameter correspondence table can include a preset correspondence between the influence factors of various parameters and the corresponding unit change values ​​of various parameters. In some embodiments, the parameter correspondence table can be obtained experimentally.

[0099] In some embodiments, the larger the influence factor of a certain type of polishing parameter, the greater the influence of that type of polishing parameter on the polishing effect. Therefore, the unit change value of the polishing parameter can be smaller to ensure that the polishing effect does not change too much when the polishing parameter changes based on the unit change value, thereby ensuring the stability of polishing. Conversely, the smaller the influence factor of a certain type of polishing parameter, the smaller the influence of that type of polishing parameter on the polishing effect. Therefore, the unit change value of the polishing parameter can be larger to reduce the number of adjustments to that type of polishing parameter and improve polishing efficiency.

[0100] In some embodiments, multiple candidate polishing parameters are generated based on monitoring indicators, including: determining the range of variation of various parameters based on the difference between the monitoring indicators and preset conditions and the influence factors of various parameters; and generating candidate polishing parameters based on the range of variation of various parameters and the unit change value of various parameters.

[0101] In some embodiments, the greater the difference between the monitoring indicators and the preset conditions, the greater the range of variation for various parameters; the smaller the difference between the monitoring indicators and the preset conditions, the smaller the range of variation for various parameters.

[0102] In some embodiments, the larger the influence factor of each parameter, the greater the range of variation of each parameter; the smaller the influence factor of each parameter, the smaller the range of variation of each parameter.

[0103] In some embodiments, within the range of variation of various parameters, multiple polishing parameters of the same type can be generated according to the corresponding unit change value. For example, within the range of variation of valve opening, multiple valve opening parameters can be generated according to the unit valve opening change value. Taking two polishing fluid supply ports as an example, where the range of variation of the valve opening of the first polishing fluid supply port is 1 to 3, and the unit valve opening change value is 0.5, multiple valve opening parameters for the first polishing fluid supply port can be generated, for example, 1, 1.5, 2, 2.5, and 3; and the range of variation of the valve opening of the second polishing fluid supply port is 0.5 to 1, and the unit valve opening change value is 0.2, multiple valve opening parameters for the second polishing fluid supply port can be generated, for example, 0.5, 0.7, and 0.9. Furthermore, multiple sets of candidate polishing parameters can be generated based on the multiple valve opening parameters of the first and second polishing fluid supply ports. Here, the candidate polishing parameters can be any one of the multiple valve opening parameters of the first polishing fluid supply port and any one of the multiple valve opening parameters of the second polishing fluid supply port. For example, multiple sets of candidate polishing parameters can include [1, 0.5], [1, 0.7], [1, 0.9], [1.5, 0.5], [1.5, 0.7], [2, 0.9], [2.5, 0.5], [3, 0.9], etc. As another example, within the range of polishing pressure variation, multiple polishing pressure parameters can be generated according to the unit polishing pressure change value.

[0104] By measuring the impact of various parameters on the polishing effect, multiple candidate polishing parameters can be generated in a targeted manner, making the generated candidate polishing parameters more reasonable.

[0105] In some embodiments, the initial polishing parameters can be adjusted based on the polishing effect and polishing risk. Figure 4 is another exemplary flowchart illustrating the adjustment of the initial polishing parameters according to some embodiments of this specification. As shown in Figure 4, process 400 may include:

[0106] Step 410: In response to the monitoring indicators meeting preset conditions, multiple candidate polishing parameters are generated based on the monitoring indicators. In some embodiments, step 410 may be executed by a processor.

[0107] For details on generating candidate polishing parameters, please refer to the previous description, such as Figure 3 and its related description, which will not be repeated here.

[0108] Step 420: Predict the polishing effect of multiple candidate polishing parameters.

[0109] In some embodiments, the polishing effect of candidate polishing parameters can be predicted using an effect prediction model based on candidate polishing parameters and monitoring indicators. For details regarding the prediction of the polishing effect of candidate polishing parameters, please refer to the relevant descriptions above, such as Figure 3 and its related descriptions, which will not be repeated here.

[0110] Step 430: Predict the polishing risk of multiple candidate polishing parameters.

[0111] Polishing risk can refer to the probability that the polished wafer will not meet quality standards. In some embodiments, polishing risk may include the probability of scratches or wafer breakage on the wafer surface.

[0112] In some embodiments, the polishing risk of candidate polishing parameters can be predicted using a risk prediction model based on candidate polishing parameters and monitoring indicators. In some embodiments, the risk prediction model includes a second machine learning model.

[0113] The input data for the second machine learning model consists of candidate polishing parameters and monitoring metrics. The output data is the polishing risk of the corresponding candidate polishing parameters. In some embodiments, the second machine learning model can be obtained by training a second initial machine learning model based on a large number of second training samples with second training labels. The second training samples may include candidate polishing parameters and monitoring metrics, as well as the polishing risk corresponding to the candidate polishing parameters, wherein the polishing risk corresponding to the candidate polishing parameters is the second training label. Specifically, the labeled second training samples can be input into the second initial machine learning model to obtain the output result of the second initial machine learning model. The parameters of the second initial machine learning model are updated through training until the trained second intermediate machine learning model meets the second preset condition, thereby obtaining the trained second machine learning model. The second preset condition may be that the loss function reflecting the difference between the output result of the second machine learning model and the second training label is less than a preset threshold, the loss function converges, or the number of training iterations reaches a preset threshold.

[0114] In some embodiments, the second training samples and labels can be obtained through various means such as historical data, networks, and human experience.

[0115] In some embodiments, the input data of the second machine learning model may further include information about the wafer to be processed and information about the polishing equipment. By including the information about the wafer to be processed and the polishing equipment as input data for the second machine learning model, polishing risks can be predicted more accurately.

[0116] In some embodiments, the input data for the second machine learning model may further include a sequence of crystal powder content in the used polishing slurry. By including the sequence of crystal powder content as input data for the second machine learning model, the accuracy of the second machine learning model in predicting polishing risks can be improved.

[0117] In some embodiments, the effect prediction model and the risk prediction model are jointly trained.

[0118] In some embodiments, the machine learning model (first machine learning model, second machine learning model) may include a feature extraction layer, which extracts feature vectors, and the effect prediction model and the risk prediction model share the feature vectors.

[0119] In some embodiments, the input data of the feature extraction layer may include information about the wafer to be processed and polishing equipment, and the output data is a feature vector. Compared to the input data (information about the wafer to be processed and polishing equipment), the output data feature vector better reflects the characteristics of the information about the wafer to be processed and polishing equipment, and the feature vector is also more suitable for training subsequent effect prediction models and risk prediction models.

[0120] In some embodiments, feature vectors can be used to train the effect prediction model and the risk prediction model. Specifically, the labeled feature vectors are input as training samples into the initial effect prediction model and the initial risk prediction model. The parameters of the initial effect prediction model and the initial prediction model are updated through training until the intermediate effect prediction model and the intermediate risk prediction model meet a third preset condition. The trained effect prediction model and risk prediction model are then obtained. The third preset condition can be that the loss function is less than a threshold, convergence, or the training period reaches a threshold.

[0121] Step 440: Based on the polishing risk and polishing effect of multiple candidate polishing parameters, determine the adjusted initial polishing parameters.

[0122] In some embodiments, after predicting the polishing effect of each candidate polishing parameter using an effect prediction model and predicting the polishing risk of each candidate polishing parameter using a risk prediction model, the relationship between the polishing risk of the candidate polishing parameter and the risk threshold can be determined first. If the polishing risk of the candidate polishing parameter is less than the risk threshold, the candidate polishing parameter with better polishing effect is determined as the adjusted initial polishing parameter; if the polishing risk of the candidate polishing parameter is greater than or equal to the risk threshold, the candidate polishing parameter is set as the default value.

[0123] It should be noted that the above description of process 400 is for illustrative purposes only and does not limit the scope of this specification. Those skilled in the art can make various modifications and changes to process 400 under the guidance of this specification. However, these modifications and changes remain within the scope of this specification.

[0124] Some embodiments of this specification also provide a computer-readable storage medium storing computer instructions that, when at least a portion of the computer instructions are executed by a processor, enable the wafer double-sided CMP polishing method as described in any embodiment of this specification. For details regarding the wafer double-sided CMP polishing method, please refer to the above description, which will not be repeated here.

[0125] Figure 5 is an exemplary frame diagram of an apparatus for double-sided CMP polishing of wafers according to some embodiments of this specification. As shown in Figure 5, the apparatus 500 for double-sided CMP polishing of wafers (referred to as polishing apparatus 500) includes a polishing disc 510, a workpiece fixture 520, a polishing slurry delivery system 530, and a frame 540. The frame 540 is used to support the polishing disc 510 and the polishing disc delivery system 530.

[0126] Polishing disc 510 is a device used to polish a wafer to be processed. Polishing disc 510 may include a first polishing disc and a second polishing disc disposed opposite each other. During polishing, the wafer to be processed is held between the first and second polishing discs, with the first polishing disc conforming to one surface of the wafer and the second polishing disc conforming to the other surface. In some embodiments, the wafer to be processed can be held between the first and second polishing discs by a workpiece clamp 520. In some embodiments, a polishing pad is provided on the surface of the polishing disc 510 (first and second polishing discs) for conforming to the wafer to be processed, and the polishing disc 510 makes contact with the wafer to be processed through the polishing pad. During the polishing process, when the polishing disc 510 is rotated, friction is generated between the polishing pad and the wafer to be processed, thereby grinding away the oxides on the surface of the wafer to be processed.

[0127] In some embodiments, the polishing disk 510 may be provided with one or more sensors. In some embodiments, the polishing disk 510 may be provided with a pressure sensor. The pressure sensor is used to detect the pressure applied to the wafer to be processed by the polishing disk 510. That is, the pressure sensor is used to detect the polishing pressure during the polishing process.

[0128] In some embodiments, a temperature sensor may also be provided on the polishing disk 510. When the polishing slurry is delivered to different areas of the wafer to be processed, the oxidant in the slurry reacts chemically with the material layer on the surface of the wafer to form oxides. In this chemical reaction, temperature can affect the reaction rate and / or the extent of the reaction. The temperature sensor can be used to detect the temperature during the polishing process to ensure the polishing rate and polishing effect.

[0129] The polishing slurry delivery system 530 is configured to deliver polishing slurry to the polishing disk 510 and / or the wafer to be processed. In some embodiments, the polishing slurry delivery system 530 can deliver polishing slurry directly to different areas of the wafer to be processed. In some embodiments, the polishing slurry delivery system 530 can also deliver polishing slurry to different locations on the polishing disk 510, with the polishing slurry on the polishing disk 510 flowing to different areas of the wafer to be processed.

[0130] In some embodiments, the polishing slurry delivery system 530 may include a plurality of polishing slurry supply ports, which are arranged corresponding to different locations on the polishing disk 510. The polishing slurry delivery system 530 delivers polishing slurry to different areas of the polishing disk 510 and / or the wafer to be processed through the plurality of polishing slurry supply ports. In some embodiments, each of the plurality of polishing slurry supply ports is provided with a valve. In some embodiments, the opening degree of the valve can be adjusted to control the flow rate of polishing slurry flowing through the corresponding polishing slurry supply port. In some embodiments, the valve opening degree can be adjusted manually or automatically. In some embodiments, the valve can be an electric valve.

[0131] In some embodiments, the polishing slurry delivery system 530 may include a plurality of polishing slurry recovery ports, which are arranged corresponding to different locations on the polishing disk 510. After the polishing slurry is applied to the wafer to be processed, at least a portion of the used polishing slurry is discharged through the plurality of polishing slurry recovery ports from locations corresponding to different regions of the wafer. In some embodiments, each of the plurality of polishing slurry recovery ports is equipped with a flow meter. The flow meter is used to measure the flow rate of the polishing slurry flowing through the corresponding polishing slurry recovery port. The flow distribution through the plurality of polishing slurry recovery ports can determine the uniformity of the polishing slurry distribution on the surface of the wafer to be processed.

[0132] In some embodiments, the polishing apparatus 500 may further include a polishing slurry recovery device configured to store used polishing slurry. At least a portion of the used polishing slurry is discharged into the polishing slurry recovery device from locations corresponding to different regions of the wafer through a plurality of polishing slurry recovery ports.

[0133] In some embodiments, the apparatus 500 may further include an optical device configured to detect the crystal powder content in the polishing slurry recovery device. In some embodiments, the optical device may include at least one light source generating device, at least one optical lens and filter, and at least one optical detection device.

[0134] The light source generating device is configured to emit a light source. In some embodiments, the light source generating device may include, but is not limited to, a laser source, a white light source, an ultraviolet-visible light source (UV-Vis), an infrared light source, etc.

[0135] Optical lenses are used to focus the light beam emitted by the light source generator. Through the focusing action of the optical lens, the light beam can be concentrated onto the used polishing slurry, improving the intensity and accuracy of the beam's illumination.

[0136] A filter is used to select light of a specific wavelength. In some embodiments, when a light beam emitted by a light source passes through a filter, the filter can select light of a specific wavelength, and the selected light passes through the filter and illuminates the used polishing slurry. The filter can filter out unwanted wavelengths of light, thereby avoiding interference with the detection results.

[0137] An optical detection device is a component that receives and records signals generated by the interaction between crystal powder and a light beam. A light beam emitted by a light source, after passing through optical structures such as lenses and filters, illuminates a used polishing slurry. The light beam interacts with the crystal powder in the slurry, generating an optical signal. The optical detection device receives and processes this optical signal to determine the crystal powder content. In some embodiments, the optical detection device may include a detector. The detector may include, but is not limited to, one or more of photodiodes, photomultiplier tubes, CCD cameras, and spectrometers.

[0138] In some embodiments, the optical device may further include a sample chamber for holding used polishing slurry. For example, at least a portion of the used polishing slurry in a polishing slurry recovery device can flow into the sample chamber before optical detection of crystal powder content is performed. In some embodiments, the sample chamber may be made of a transparent material (such as quartz, glass, etc.) to ensure that a light beam can pass through the sample chamber and irradiate the used polishing slurry.

[0139] In some embodiments, the optical device may further include a stirring device. Since the crystal powder is distributed in the used polishing slurry, the crystal powder may settle or aggregate. The stirring device can agitate the powder to ensure uniform distribution in the used polishing slurry, preventing crystal powder settling or aggregation that could lead to inaccurate detection results.

[0140] In some embodiments, the polishing apparatus 500 may further include a control system. In some embodiments, the control system may control the operation of components of the polishing apparatus. For example, the control system may control the rotation or stopping of the polishing disc. In some embodiments, the control system may also control the operating state of the polishing apparatus 500. For example, the control system may start or stop the polishing apparatus 500, or adjust the polishing apparatus 500 to a standby state.

[0141] The basic concepts have been described above. Obviously, for those skilled in the art, the detailed disclosure above is merely illustrative and does not constitute a limitation of this specification. Although not explicitly stated herein, those skilled in the art may make various modifications, improvements, and corrections to this specification. Such modifications, improvements, and corrections are suggested in this specification and therefore remain within the spirit and scope of the exemplary embodiments described herein.

[0142] Furthermore, this specification uses specific terms to describe embodiments thereof. For example, "an embodiment," "one embodiment," and / or "some embodiments" refer to a particular feature, structure, or characteristic associated with at least one embodiment of this specification. Therefore, it should be emphasized and noted that references to "an embodiment," "one embodiment," or "an alternative embodiment" in different locations throughout this specification do not necessarily refer to the same embodiment. Moreover, certain features, structures, or characteristics in one or more embodiments of this specification can be appropriately combined.

[0143] Furthermore, unless expressly stated in the claims, the order of processing elements and sequences, the use of numbers and letters, or other names described in this specification are not intended to limit the order of the processes and methods described herein. Although various examples have been discussed in the foregoing disclosure of some embodiments of the invention that are currently considered useful, it should be understood that such details are for illustrative purposes only, and the appended claims are not limited to the disclosed embodiments; rather, the claims are intended to cover all modifications and equivalent combinations that conform to the spirit and scope of the embodiments described herein. For example, while the system components described above can be implemented using hardware devices, they can also be implemented solely using software solutions, such as installing the described system on existing servers or mobile devices.

[0144] Similarly, it should be noted that, in order to simplify the description disclosed herein and thus aid in the understanding of one or more embodiments of the invention, the foregoing description of embodiments in this specification may sometimes combine multiple features into a single embodiment, drawing, or description thereof. However, this method of disclosure does not imply that the subject matter of this specification requires more features than those mentioned in the claims. In fact, the embodiments contain fewer features than all the features of a single embodiment disclosed above.

[0145] In some embodiments, numbers describing the quantity of components and attributes are used. It should be understood that such numbers used in the description of embodiments are modified in some examples with the terms "approximately," "approximately," or "generally." Unless otherwise stated, "approximately," "approximately," or "generally" indicates that the numbers are allowed to vary by ±20%. Accordingly, in some embodiments, the numerical parameters used in the specification and claims are approximate values, which may be changed depending on the characteristics required by individual embodiments. In some embodiments, numerical parameters should take into account specified significant digits and employ a general method of digit reservation. Although the numerical ranges and parameters used to confirm their breadth of range in some embodiments of this specification are approximate values, in specific embodiments, such values ​​are set as precisely as feasible.

[0146] For each patent, patent application, patent application publication, and other material, such as articles, books, specifications, publications, and documents, referenced in this specification, the entire contents of which are incorporated herein by reference. This excludes historical application documents that are inconsistent with or conflict with the content of this specification, as well as documents that limit the broadest scope of the claims in this specification (currently or subsequently appended to this specification). It should be noted that in the event of any inconsistency or conflict between the descriptions, definitions, and / or terminology used in the supplementary materials to this specification and the content of this specification, the descriptions, definitions, and / or terminology used in this specification shall prevail.

[0147] Finally, it should be understood that the embodiments described in this specification are merely illustrative of the principles of the embodiments described herein. Other variations may also fall within the scope of this specification. Therefore, alternative configurations of the embodiments described herein are intended to be illustrative rather than limiting, and should be considered consistent with the teachings of this specification. Accordingly, the embodiments described herein are not limited to those explicitly introduced and described herein.

Claims

1. A method for double-sided CMP polishing of a wafer, comprising: Based on the monitoring indicators during the polishing process, determine one or more sets of polishing parameters; as well as Polishing is performed on the wafer to be processed based on one or more sets of polishing parameters.

2. The method according to claim 1, wherein, The determination of one or more sets of polishing parameters based on monitoring indicators during polishing includes: Obtain initial polishing parameters; The wafer to be processed is polished based on the initial polishing parameters; Obtain the monitoring indicators during the polishing process; Based on the monitoring indicators, the initial polishing parameters are adjusted to obtain one or more sets of polishing parameters.

3. The method according to claim 1, wherein, The polishing parameters include the valve opening of multiple polishing fluid supply ports, and the monitoring indicators include the uniformity of polishing fluid distribution, which is represented by the flow distribution of multiple polishing fluid recovery ports. The plurality of polishing slurry supply ports are used to supply polishing slurry to different areas of the wafer to be processed, and the plurality of polishing slurry return ports are used to discharge at least a portion of the used polishing slurry from positions corresponding to different areas of the wafer to be processed.

4. The method according to claim 1, wherein, The polishing parameters also include polishing pressure and polishing speed.

5. The method according to claim 2, wherein, The adjustment of the initial polishing parameters based on the monitoring indicators includes: In response to the monitoring indicators meeting preset conditions, multiple candidate polishing parameters are generated based on the monitoring indicators; Predict the polishing effect of multiple candidate polishing parameters; Based on the polishing effect of multiple candidate polishing parameters, the adjusted initial polishing parameters are determined.

6. The method according to claim 5, wherein, The wafer to be processed is a SiC wafer, and the polishing effect includes at least one of the C-side polishing effect, the Si-side polishing effect, and the combined polishing effect, wherein the combined polishing effect is determined based on the C-side polishing effect and the Si-side polishing effect.

7. The method according to claim 5, wherein, Before generating multiple candidate polishing parameters based on the monitoring indicators, the method further includes: Determine the influence factors of various parameters in the initial polishing parameters; Based on the influence factors of the various parameters, the unit change value of the various parameters is determined.

8. The method according to claim 7, wherein, Based on the monitoring indicators, multiple candidate polishing parameters are generated, including: Based on the differences between the monitoring indicators and the preset conditions, as well as the influencing factors of the various parameters, the range of variation of the various parameters is determined; The candidate polishing parameters are generated based on the variation range of the various parameters and the unit variation value of the various parameters.

9. The method according to claim 5, wherein, The prediction of the polishing effect of the multiple candidate polishing parameters includes: Based on the candidate polishing parameters and the monitoring indicators, the polishing effect of the candidate polishing parameters is predicted by an effect prediction model, which is a machine learning model.

10. The method according to claim 9, wherein, The input data for the effect prediction model also includes a sequence of crystal powder content stored in the polishing slurry recovery device. The sequence of crystal powder content includes the crystal powder content in the used polishing slurry corresponding to time points distributed according to preset time intervals within a preset historical time period.

11. The method according to claim 10, wherein, The method further includes: Based on the sequence of crystal powder content, determine whether the growth rate of the crystal powder is abnormal; In response to an abnormal growth rate of the crystal powder, the current polishing parameters are adjusted and a warning message is issued.

12. The method according to claim 2, wherein, The adjustment of the initial polishing parameters based on the monitoring indicators includes: In response to the monitoring indicators meeting preset conditions, multiple candidate polishing parameters are generated based on the monitoring indicators; Predict the polishing effect of multiple candidate polishing parameters; Predict the polishing risk of multiple candidate polishing parameters; Based on the polishing risk and polishing effect of the multiple candidate polishing parameters, the adjusted initial polishing parameters are determined.

13. The method according to claim 12, wherein, The method of predicting the polishing risk of multiple candidate polishing parameters includes: predicting the polishing risk of the candidate polishing parameters based on the candidate polishing parameters and the monitoring indicators, using a risk prediction model, wherein the risk prediction model is a machine learning model; The method of predicting the polishing effect of multiple candidate polishing parameters includes: based on the candidate polishing parameters and the monitoring indicators, predicting the polishing effect of the candidate polishing parameters using an effect prediction model, wherein the effect prediction model is a machine learning model.

14. The method according to claim 13, wherein, The effect prediction model and the risk prediction model are obtained through joint training.

15. A computer-readable storage medium storing computer instructions that, when at least a portion of the computer instructions are executed by a processor, enable the wafer double-sided CMP polishing method as described in any one of claims 1 to 14.

16. An apparatus for double-sided CMP polishing of wafers, comprising: The polishing disc includes a first polishing disc and a second polishing disc disposed opposite to each other, and the workpiece fixture is used to hold the wafer to be processed between the first polishing disc and the second polishing disc; A polishing slurry delivery system is configured to deliver polishing slurry to the polishing pad and / or the wafer to be processed; as well as A frame for supporting the polishing disc and the polishing fluid delivery system.

17. The apparatus according to claim 16, wherein, The polishing slurry delivery system includes multiple polishing slurry supply ports and multiple polishing slurry return ports. The multiple polishing slurry supply ports are arranged at different positions on the polishing disc, and the multiple polishing slurry return ports are arranged at different positions on the polishing disc. Each of the plurality of polishing fluid supply ports is provided with a valve, and each of the plurality of polishing fluid recovery ports is provided with a flow meter.

18. The apparatus according to claim 16, wherein, The polishing disc is equipped with a pressure sensor and / or a temperature sensor.

19. The apparatus according to claim 16, wherein, The device also includes a polishing slurry recovery unit configured to store used polishing slurry.

20. The apparatus according to claim 16, wherein, The device also includes an optical device configured to detect the crystal powder content in the polishing slurry recovery device.

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