Method and monitoring device for stress monitoring of wafer thinning sheet, and semiconductor process equipment

Abstract

The present disclosure provides a stress monitoring method and monitoring device for a wafer thinning sheet, and a semiconductor process equipment. In the stress monitoring method, a plurality of stress monitoring components are correspondingly arranged at a plurality of monitoring points of a wafer heating plate, and a strain monitoring circuit is constructed by combining resistive strain sensors in the plurality of stress monitoring components; measured data of electrical parameters related to each resistive strain sensor is obtained, and by comparing the measured data of the electrical parameters related to each resistive strain sensor with its reference value, the change amount and change distribution characteristics of the electrical parameters related to each resistive strain sensor are obtained, and it is determined whether there are problems of displacement or warping of the wafer thinning sheet. This technical solution has a simple process, does not affect the semiconductor process, has accurate detection, and when it is monitored that there are displacement or warping of the wafer thinning sheet, corresponding adjustment measures are taken, which is beneficial to the subsequent semiconductor wafer manufacturing process and improves the yield.

Description

Technical Field

[0001] The present disclosure relates to the field of semiconductor technology, and in particular, to a method and device for monitoring the stress of a wafer thinning sheet, a semiconductor processing equipment, and a control device for monitoring the stress of a wafer thinning sheet. Background Art

[0002] Photoresist can be used as a pattern conversion medium from a photomask to a wafer during the lithography process and as a protective film for areas that do not need to be etched during etching. During the manufacturing process of a wafer, after etching or ion implantation, photoresist is no longer needed as a protective layer, so the photoresist can be removed from the surface of the silicon wafer, and this process is called photoresist stripping.

[0003] The methods of photoresist stripping mainly include wet stripping and dry stripping. Plasma stripping is common in dry stripping. Taking plasma stripping as an example, when using a plasma stripping device, high-frequency electromagnetic waves are used to ionize oxygen into plasma under the action of a high-frequency electric field. Its oxidation ability is very strong, and it reacts with the photoresist to make the photoresist become a volatile substance that can be pumped away by a vacuum system to achieve the purpose of photoresist stripping.

[0004] A wafer thinning sheet is a wafer with a thickness thinner than that of a normal wafer. Compared with a normal wafer, the wafer thinning sheet has the advantages of reducing the packaging and chip mounting height, reducing the chip packaging volume, improving the thermal diffusion efficiency, electrical performance, and mechanical performance of the chip, and reducing the processing amount of dicing, and can be used in the manufacturing of various products such as chips, solar cells, and power semiconductor devices. However, due to its thin and light characteristics, the wafer thinning sheet is more susceptible to stress in the photoresist stripping process, resulting in edge warping or displacement. This stress may come from factors such as mechanical pressure or temperature fluctuations of the equipment. If the wafer thinning sheet has edge warping or displacement, it will have a serious impact on the uniformity of photoresist stripping and subsequent processes, thereby having an adverse impact on various aspects such as the product defect rate and production efficiency of the entire manufacturing process. Summary of the Invention

[0005] In view of the above-mentioned disadvantages of the related art, the purpose of the present disclosure is to provide a method and device for monitoring the stress of a wafer thinning sheet, a semiconductor processing equipment, and a control device for monitoring the stress of a wafer thinning sheet, so as to solve various problems in the related art.

[0006] The first aspect of the present disclosure provides a method for monitoring the stress of a wafer thinning sheet, which is applied to a semiconductor processing equipment. The method for monitoring the stress of the wafer thinning sheet includes the following steps:

[0007] Provide a stress monitoring device for a wafer thinning sheet, and configure the stress monitoring device for the wafer thinning sheet in a semiconductor processing equipment; the stress monitoring device for the wafer thinning sheet includes a plurality of stress monitoring components, which are correspondingly arranged at a plurality of monitoring points of a wafer heating plate; each stress monitoring component includes a telescopic thimble, the telescopic thimble has a supporting portion for supporting the wafer thinning sheet and a bottom opposite to the supporting portion, and a resistive strain sensor is connected to the bottom of the telescopic thimble; the resistive strain sensors in the plurality of stress monitoring components are combined and connected to construct a strain monitoring circuit;

[0008] Obtain the measured data of the electrical parameters related to the resistive strain sensors in each stress monitoring component in the strain monitoring circuit;

[0009] By comparing the measured data of the electrical parameters related to the resistive strain sensors in each stress monitoring component with the reference values of the electrical parameters, obtain the change amount and change distribution characteristics of the electrical parameters related to each resistive strain sensor, and accordingly determine whether there are problems such as displacement or warping of the wafer thinning sheet.

[0010] In some examples of the first aspect, the resistive strain sensors in the plurality of stress monitoring components are combined and connected to construct a strain monitoring circuit, including: the resistive strain sensors in the plurality of stress monitoring components are combined and connected in parallel to construct a constant voltage shunt type strain monitoring circuit; the obtaining of the measured data of the electrical parameters related to the resistive strain sensors in each stress monitoring component in the strain monitoring circuit includes: obtaining the measured current signals related to the resistive strain sensors in each stress monitoring component in the constant voltage shunt type strain monitoring circuit; or, the resistive strain sensors in the plurality of stress monitoring components are combined and connected to construct a strain monitoring circuit, including: the resistive strain sensors in the plurality of stress monitoring components are combined and connected in series to construct a constant current voltage division type strain monitoring circuit; the obtaining of the measured data of the electrical parameters related to the resistive strain sensors in each stress monitoring component in the strain monitoring circuit includes: obtaining the measured voltage signals related to the resistive strain sensors in each stress monitoring component in the constant current voltage division type strain monitoring circuit.

[0011] In some examples of the first aspect, in the constant-voltage shunt-type strain monitoring circuit, when the top supporting part of the telescopic thimble in a certain stress monitoring component is subjected to a decreasing pressure from the wafer thinning sheet, it will extend and drive the resistive strain sensor at the bottom to stretch. After being stretched, the length of the resistive strain sensor increases and the cross-sectional area decreases, resulting in an increase in the resistance value. The measured current value related to the resistive strain sensor becomes smaller, that is, the measured current value related to the resistive strain sensor is less than the reference value of the current parameter. When the top supporting part of the telescopic thimble in a certain stress monitoring component is subjected to an increasing pressure from the wafer thinning sheet, it will contract and drive the resistive strain sensor at the bottom to compress. After being compressed, the length of the resistive strain sensor decreases and the cross-sectional area increases, resulting in a decrease in the resistance value. The measured current value related to the resistive strain sensor becomes larger, that is, the measured current value related to the resistive strain sensor is greater than the reference value of the current parameter. Or, in the constant-current voltage-dividing type strain monitoring circuit, when the top supporting part of the telescopic thimble in a certain stress monitoring component is subjected to a decreasing pressure from the wafer thinning sheet, it will extend and drive the resistive strain sensor at the bottom to stretch. After being stretched, the length of the resistive strain sensor increases and the cross-sectional area decreases, resulting in an increase in the resistance value. The measured voltage value related to the resistive strain sensor becomes larger, that is, the measured voltage value related to the resistive strain sensor is greater than the reference value of the voltage parameter. When the top supporting part of the telescopic thimble in a certain stress monitoring component is subjected to an increasing pressure from the wafer thinning sheet, it will contract and drive the resistive strain sensor at the bottom to compress. After being compressed, the length of the resistive strain sensor decreases and the cross-sectional area increases, resulting in a decrease in the resistance value. The measured voltage value related to the resistive strain sensor becomes smaller, that is, the measured voltage value related to the resistive strain sensor is less than the reference value of the voltage parameter.

[0012] In some examples of the first aspect, the stress monitoring method for the wafer thinning sheet further includes the step of creating an electrical parameter reference database, in which the reference values of the electrical parameters related to each resistive strain sensor are recorded. The creating of the electrical parameter reference database includes the following steps: placing the reference wafer thinning sheet on the wafer heating plate and performing station calibration; using multiple telescopic thimbles in the wafer thinning sheet stress monitoring device to support the reference wafer thinning sheet to different detection positions and detecting the values of the electrical parameters corresponding to different detection positions; creating the electrical parameter reference database according to the obtained different detection positions and the corresponding values of the electrical parameters.

[0013] The second aspect of the present disclosure provides a stress monitoring device for a wafer thinning sheet, which is applied to semiconductor process equipment. The stress monitoring device for the wafer thinning sheet includes: a plurality of stress monitoring components, which are respectively arranged at a plurality of monitoring points on a wafer heating plate; each stress monitoring component includes a telescopic ejector pin, the telescopic ejector pin has a supporting part for supporting the wafer thinning sheet and a bottom opposite to the supporting part, and a resistive strain sensor is connected to the bottom of the telescopic ejector pin; the resistive strain sensors in the plurality of stress monitoring components are combined and connected to construct a strain monitoring circuit; the measured data of the electrical parameters related to the resistive strain sensors in each stress monitoring component are obtained by using the strain monitoring circuit, and the change amount and change distribution characteristics of the electrical parameters related to each resistive strain sensor are obtained by comparing the measured data of the electrical parameters related to the resistive strain sensors in each stress monitoring component with the reference value of the electrical parameters, so as to determine whether there are problems such as displacement or warping of the wafer thinning sheet.

[0014] In some examples of the second aspect, the resistive strain sensors in the plurality of stress monitoring components are combined and connected to construct a strain monitoring circuit, including: the resistive strain sensors in the plurality of stress monitoring components are combined and connected in parallel to construct a constant voltage shunt type strain monitoring circuit; or, the resistive strain sensors in the plurality of stress monitoring components are combined and connected in series to construct a constant current voltage division type strain monitoring circuit.

[0015] In some examples of the second aspect, the plurality of monitoring points are evenly distributed in the edge area of the wafer heating plate, the monitoring points are detection holes penetrating the wafer heating plate, and after the telescopic ejector pin penetrates through the detection holes, the supporting part of the telescopic ejector pin protrudes from the wafer heating plate.

[0016] In some examples of the second aspect, the telescopic ejector pin includes: a housing, a supporting member embedded in the housing and partially protruding, and an elastic member arranged in the housing and acting on the supporting member, the elastic member is associated with the resistive strain sensor; or, the telescopic ejector pin is an ejector pin made of an elastic material.

[0017] The third aspect of the present disclosure provides a semiconductor process equipment, including the stress monitoring device for the wafer thinning sheet as described above.

[0018] The fourth aspect of the present disclosure provides a stress monitoring control device for a wafer thinning sheet, including: a processor; a memory storing a stress monitoring program for the wafer thinning sheet; wherein, when the stress monitoring program for the wafer thinning sheet is run by the processor, it executes the stress monitoring method for the wafer thinning sheet as described above.

[0019] As described above, the embodiments of the present disclosure provide a stress monitoring method and a stress monitoring device for a wafer thinning sheet, a semiconductor processing device, and a stress monitoring control device, which can be used to monitor the stress of the wafer thinning sheet. In the stress monitoring method, first, a stress monitoring device for the wafer thinning sheet is provided, and a plurality of stress monitoring components are respectively arranged at a plurality of monitoring points of the wafer heating plate. The resistive strain sensors in the plurality of stress monitoring components are combined and connected to construct a strain monitoring circuit. Then, the measured data of the electrical parameters related to the resistive strain sensors in each stress monitoring component are obtained according to the strain monitoring circuit. By comparing the measured data of the electrical parameters related to the resistive strain sensors in each stress monitoring component with the reference values of the electrical parameters, the change amount and the change distribution characteristics of the electrical parameters related to each resistive strain sensor are obtained, and based on this, it is determined whether there are problems such as displacement or warping of the wafer thinning sheet. Compared with the related art, the stress monitoring method for the wafer thinning sheet provided by the present disclosure has the advantages of simple process, no influence on the semiconductor process, accurate detection, and taking corresponding adjustment measures when it is monitored that the wafer thinning sheet has displacement or warping is beneficial to the subsequent semiconductor wafer manufacturing process and improves the yield. Description of the Drawings

[0020] Figure 1 It shows a schematic structural diagram of a semiconductor processing device to which the stress monitoring method for the wafer thinning sheet of the present disclosure is applied in an embodiment.

[0021] Figure 2 It shows a schematic flow chart of the stress monitoring method for the wafer thinning sheet provided by the present disclosure in an embodiment.

[0022] Figure 3 It shows a schematic diagram of the state where the stress monitoring device is configured in the semiconductor processing device.

[0023] Figure 4 It shows a schematic circuit diagram of a constant voltage shunt type strain monitoring circuit constructed by combining and connecting resistive strain sensors in parallel in the configuration of the stress monitoring device.

[0024] Figure 5 It shows a schematic circuit diagram of a constant current voltage division type strain monitoring circuit constructed by combining and connecting resistive strain sensors in series in the configuration of the stress monitoring device.

[0025] Figure 6 It shows an application schematic diagram of the constant voltage shunt type strain monitoring circuit when the wafer thinning sheet warps upward or when the wafer thinning sheet is displaced and leaves.

[0026] Figure 7 It shows an application schematic diagram of the constant voltage shunt type strain monitoring circuit when the wafer thinning sheet warps downward or when the wafer thinning sheet is displaced and approaches.

[0027] Figure 8 It shows a schematic diagram of the application of the constant-current voltage-dividing type strain monitoring circuit when the wafer thinning sheet warps upward or when the wafer thinning sheet shifts away.

[0028] Figure 9 It shows a schematic diagram of the application of the constant-current voltage-dividing type strain monitoring circuit when the wafer thinning sheet warps downward or when the wafer thinning sheet shifts closer.

[0029] Figure 10 It shows a top view of the wafer thinning sheet configured in the stress monitoring device.

[0030] Figure 11 It shows a schematic diagram of the current-time change of the constant-voltage current-dividing type strain monitoring circuit constructed by parallel connection of resistive strain sensors in multiple stress monitoring components in different examples.

[0031] Figure 12 It shows a schematic diagram of the voltage-time change of the constant-current voltage-dividing type strain monitoring circuit constructed by series connection of resistive strain sensors in multiple stress monitoring components in different examples.

[0032] Figure 13 It shows a principle block diagram of the wafer thinning sheet stress monitoring and control device provided by the present disclosure in an embodiment. Specific Embodiments

[0033] The following uses specific examples to illustrate the embodiments of the present disclosure. Those skilled in the art can easily understand other advantages and effects of the present disclosure from the information disclosed in the present disclosure. The present disclosure can also be implemented or applied through other different specific embodiments. Various details in the present disclosure can also be modified or changed according to different viewpoints and application modules without departing from the spirit of the present disclosure. It should be noted that, without conflict, the embodiments and features in the embodiments of the present disclosure can be combined with each other.

[0034] The following takes the drawings as a reference and details the embodiments of the present disclosure so that those skilled in the technical field to which the present disclosure belongs can easily implement it. The present disclosure can be embodied in many different forms and is not limited to the embodiments described herein.

[0035] In the descriptions of the present disclosure, statements referring to terms such as "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. mean that the specific features, structures, materials, or characteristics represented by combining with the embodiment or example are included in at least one embodiment or example of the present disclosure. Moreover, the specific features, structures, materials, or characteristics represented can be combined in a suitable manner in any one or a group of embodiments or examples. In addition, without contradiction, those skilled in the art can combine and combine the different embodiments or examples represented in the present disclosure and the features of different embodiments or examples.

[0036] In addition, the terms "first" and "second" are only used for representational purposes and cannot be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" can explicitly or implicitly include at least one of such features. In the descriptions of the present disclosure, the meaning of "a group" is two or more, unless otherwise specifically defined.

[0037] To clearly illustrate the present disclosure, devices irrelevant to the description are omitted, and the same or similar components throughout the specification are given the same reference numerals.

[0038] Throughout the specification, when it is said that a device is "connected" to another device, this includes not only the case of "direct connection", but also the case of "indirect connection" with other elements placed therebetween. In addition, when it is said that a certain device "includes" a certain component, unless there is a particularly contrary record, it does not exclude other components, but means that other components can also be included.

[0039] Although in some examples the terms first, second, etc. are used herein to represent various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. For example, the first interface and the second interface etc. are represented. Furthermore, as used herein, the singular forms "a", "an", and "the" are also intended to include the plural forms, unless the context indicates otherwise. It should be further understood that the terms "comprise", "include" indicate the presence of the stated features, steps, operations, elements, modules, items, kinds, and / or groups, but do not exclude the presence, occurrence, or addition of one or a group of other features, steps, operations, elements, modules, items, kinds, and / or groups. The term "or" and "and / or" used herein are interpreted as inclusive, or meaning any one or any combination. Thus, "A, B, or C" or "A, B, and / or C" means "any one of the following: A; B; C; A and B; A and C; B and C; A, B, and C". An exception to this definition only occurs when the combination of elements, functions, steps, or operations is inherently mutually exclusive in some way.

[0040] The technical terms used herein are only for referring to specific embodiments and are not intended to limit the present disclosure. The singular forms used herein also include the plural forms as long as the statements do not clearly indicate the contrary meaning. The meaning of "including" used in the specification is to embody specific characteristics, regions, integers, steps, operations, elements and / or components, and does not exclude the existence or addition of other characteristics, regions, integers, steps, operations, elements and / or components.

[0041] Although not defined differently, including the technical terms and scientific terms used herein, all terms have the same meaning as generally understood by those skilled in the art to which the present disclosure pertains. Terms defined in commonly used dictionaries are additionally interpreted to have meanings consistent with the relevant technical literature and the currently presented information, and shall not be overly interpreted as ideal or overly formulaic meanings as long as they are not defined.

[0042] In the related art of semiconductor processes involving wafer thinning, due to its thin and light characteristics, the wafer thin film is more susceptible to stress during process treatment (e.g., the de-glueing process), resulting in edge warping or overall displacement, which will seriously affect the uniformity of de-glueing and subsequent processes, thereby having an adverse impact on various aspects such as the product defect rate and production efficiency of the entire manufacturing process.

[0043] Embodiments of the present disclosure provide a stress monitoring method for a wafer thin film, which is used to monitor the stress of the wafer thin film applied in semiconductor process equipment, and the semiconductor process equipment is used to perform corresponding process treatments on the wafer thin film.

[0044] The wafer thin film is a wafer with a thickness thinner than that of a normal wafer, and a plurality of chips are arranged on the wafer thin film. In some embodiments, the wafer thin film can be formed by mechanically thinning a normal wafer, with its middle part being thinner and the periphery having the same size and thickness as the normal wafer. In some embodiments, the wafer thin film is made by a manufacturing process similar to that of a normal wafer.

[0045] In some embodiments, taking the ashing process as an example, during the manufacturing process of a wafer, the wafer thinning sheet will be subjected to processes such as etching or ion implantation. After that, the wafer thinning sheet will be ashed through an ashing device. The ashing methods mainly include wet ashing and dry ashing. Compared with wet ashing, plasma dry ashing uses high-energy plasma to treat the surface of the photoresist, with thorough ashing and high speed, without introducing chemical substances, reducing the corrosion and damage to the wafer material, and is the preferred method in the existing ashing process. However, due to its thin and light characteristics, the wafer thinning sheet is prone to being affected by stress during the ashing process, resulting in edge warping or displacement, which needs to be avoided. Therefore, it is necessary to monitor the stress of the wafer thinning sheet during the ashing process.

[0046] In the following description, the semiconductor process equipment will be described by taking the wafer ashing device as an example.

[0047] Figure 1 Shown is a schematic structural diagram of a semiconductor process equipment applied to the stress monitoring method of the wafer thinning sheet of the present disclosure in an embodiment. Figure 1 The semiconductor process equipment shown in is a wafer ashing device.

[0048] As Figure 1 shown, this embodiment provides a wafer ashing device 1, which includes an ashing chamber 10, a wafer heating plate 11, at least one gas inlet device, and an exhaust device. Taking plasma dry ashing as an example, the wafer ashing device 1 can be, for example, an ICP (Inductive Coupled Plasma) ashing device or a CCP (Capacitive Coupled Plasma) ashing device, etc.

[0049] The ashing chamber 10 includes a sealed chamber with side walls, and a wafer heating plate 11 is arranged in the central area of the sealed chamber.

[0050] A top cover is provided on the upper part of the ashing chamber 10, and a nozzle or nozzle assembly facing the wafer heating plate 11 is provided on the top cover for spraying process gas onto the wafer heating plate 11.

[0051] The nozzle or nozzle assembly is connected to at least one gas inlet device for delivering process gas into the ashing chamber 10. Each gas inlet device includes an inlet pipeline and a gas source and a gas source valve arranged on the inlet pipeline. The process gas that the gas source can provide can be, for example, oxygen (O 2 ), nitrogen (N 2 ), etc.

[0052] An inlet / outlet port may be provided on the side wall of the stripping chamber 10. The transfer of related workpieces can be achieved by using the inlet / outlet port. The workpieces include, but are not limited to, wafers, wafer thinning sheets, etc. Generally, a first slit valve is provided at the inlet / outlet port, and the first slit valve can move in the up / down direction or left / right direction relative to the inlet / outlet port.

[0053] The wafer heating plate is arranged in the stripping chamber and is used to carry the semiconductor wafer and heat it. As Figure 1 shown, the wafer heating plate 11 is arranged in the stripping chamber 10 and is used to carry the wafer thinning sheet 100 to be stripped and heat it. In some embodiments, one wafer heating plate 11 is provided in the stripping chamber 10, and only one wafer is subjected to the thin film deposition process in the stripping chamber 10 at a time. Therefore, the wafer heating plate 11 is located at the central position of the stripping chamber 10. In some embodiments, two or more wafer heating plates are provided in the stripping chamber, and each wafer heating plate is arranged centered on the axis of the stripping chamber.

[0054] In some embodiments, the wafer heating plate 11 may be associated with a moving component. By using the moving component, the wafer heating plate 11 can be driven to move. Exemplarily, the moving component may be a lifting component, which can drive the wafer heating plate 11 and the wafer thinning sheet 100 carried thereon to move up and down.

[0055] In some embodiments, the wafer heating plate 11 may also be associated with a rotating device. The rotating device may include a selected rotating member and a rotating power mechanism. The rotating member may be hermetically arranged with the wafer heating plate 11 and the stripping chamber 10, and the selected power mechanism can drive the rotating member and the associated wafer heating plate 11 and the wafer thinning sheet 100 carried thereon to perform reciprocating rotation.

[0056] The exhaust device is used to extract the process gas in the stripping chamber. In some embodiments, the exhaust device includes an exhaust pipeline connected to the stripping chamber 10 and an exhaust valve and an exhaust pump provided on the exhaust pipeline.

[0057] Taking the wafer stripping equipment as an ICP stripping equipment as an example, a plasma generator (not shown in the figure) is also provided in the stripping chamber. In some embodiments, the plasma generator may be located at the top of the stripping chamber. Exemplarily, an ionization chamber communicating with the stripping colloid may be provided at the top of the stripping chamber, and the plasma generator is arranged in the ionization chamber.

[0058] Using the plasma generator, the input gas can be ionized to generate plasma. The plasma has extremely high energy density and reaction activity under a strong electric field, which can quickly break the chemical bonds on the material surface, decompose the surface attachments into small molecules or atoms, and oxidize or reduce them, thereby removing the surface attachments and realizing the degumming of the wafer thinning sheet. The exhaust device is used to discharge the gas and particles generated during the degumming process from the degumming chamber. Taking oxygen O 2 as an example, an appropriate amount of oxygen O 2 is transported into the degumming chamber by the intake device, and the oxygen O 2 is ionized by the plasma generator to generate a plasma mixture of oxygen ions, free oxygen atoms O*, oxygen molecules and electrons. Among them, the free oxygen atoms O* with strong oxidation ability react with the photoresist film under the action of high-frequency voltage to generate CO 2 and H 2 O, which are discharged through the exhaust device, thus realizing degumming.

[0059] When degumming the wafer thinning sheet, due to its thin and light characteristics, the wafer thinning sheet is more vulnerable to stress in the degumming process, resulting in edge warping or overall displacement. Edge warping or overall displacement will have a serious impact on the uniformity of degumming and subsequent process steps, thus having an adverse impact on various aspects such as the product defect rate and production efficiency of the entire manufacturing process. Therefore, it is necessary to monitor the stress of the wafer thinning sheet during the degumming process to detect whether there are problems of warping or displacement of the wafer thinning sheet.

[0060] Please refer to Figure 2 , which shows a schematic flow chart of the stress monitoring method for the wafer thinning sheet provided by the present disclosure in an embodiment.

[0061] Step S201, provide a stress monitoring device for the wafer thinning sheet, and configure the stress monitoring device for the wafer thinning sheet in a semiconductor process equipment.

[0062] In some embodiments, the stress monitoring device for the wafer thinning sheet includes a plurality of stress monitoring components, and the plurality of stress monitoring components are respectively arranged at a plurality of monitoring points of the wafer heating plate. Each stress monitoring component includes a telescopic thimble. The telescopic thimble has a top supporting portion for supporting the wafer thinning sheet and a bottom opposite to the top supporting portion. A resistive strain sensor is connected to the bottom of the telescopic thimble; the resistive strain sensors in the plurality of stress monitoring components are combined and connected to construct a strain monitoring circuit.

[0063] As Figure 3As shown, a plurality of monitoring points are provided on the wafer heating plate 11. In some embodiments, the monitoring points may be, for example, detection holes penetrating the wafer heating plate 11. Since the thickness of the wafer thinning sheet is relatively thin, warping or overall displacement is more likely to occur at its edge and the resulting warping or displacement effect is more obvious. Therefore, a plurality of monitoring points may be evenly arranged at the edge of the wafer heating plate 11.

[0064] When configuring the stress monitoring device for the wafer thinning sheet, the telescopic ejector pin 21 in the stress monitoring component is correspondingly inserted through the detection hole on the wafer heating plate 11.

[0065] Exemplarily, four monitoring points may be provided at the edge of the wafer heating plate 11, and these four monitoring points are evenly distributed. For example, the four monitoring points form a square at intervals of 90° and are all on the circumference of a formed monitoring circle. Exemplarily, six monitoring points may be provided at the edge of the wafer heating plate 11, and these six monitoring points are evenly distributed. For example, the four monitoring points form a regular hexagon at intervals of 60° and are all on the circumference of a formed monitoring circle. Exemplarily, eight monitoring points may be provided at the edge of the wafer heating plate 11, and these eight monitoring points are evenly distributed. For example, the four monitoring points form a regular octagon at intervals of 45° and are all on the circumference of a formed monitoring circle. Exemplarily, eight monitoring points may be provided at the edge of the wafer heating plate 11, and these eight monitoring points are divided into two groups with four in each group. The four monitoring points in each group are evenly distributed. For example, the four monitoring points in each group form a square at intervals of 45° and are all on the circumference of a formed monitoring circle. In this way, the two groups can form two squares of different sizes or two monitoring circles of different diameters.

[0066] After the telescopic ejector pin 21 is inserted through the detection hole, the top supporting portion of the telescopic ejector pin 21 protrudes above the upper side of the wafer heating plate 11. In this way, the plurality of top supporting portions protruding from the wafer heating plate 11 among the plurality of telescopic ejector pins 21 can form a top supporting surface for supporting the wafer thinning sheet.

[0067] Among them, the top supporting surface is matched with the bottom surface of the wafer thinning sheet to be supported. Exemplarily, if the bottom surface of the wafer thinning sheet is a plane, the top supporting surface formed by the plurality of top supporting portions of the plurality of telescopic ejector pins 21 is a horizontal plane. Exemplarily, if the bottom surface of the wafer thinning sheet is concave in the middle relative to the edge, the top supporting surface formed by the plurality of top supporting portions of the plurality of telescopic ejector pins 21 is a convex surface convex in the middle, that is, the top supporting portion of the telescopic ejector pin 21 located inside is higher than the top supporting portion of the telescopic ejector pin 21 located outside.

[0068] The bottom of the retractable ejector pin 21 can protrude relative to the supporting part from the lower side of the wafer heating plate 11. A resistive strain sensor 23 is connected to the bottom of the retractable ejector pin 21. The resistive strain sensor 23 will generate a change in resistance value after being stretched or pressed by the retractable ejector pin 21.

[0069] Exemplarily, the retractable ejector pin 21 can be made of a material with high hardness and a smooth surface to avoid scratching the wafer thinning sheet 100.

[0070] Exemplarily, the resistive strain sensor 23 and the retractable ejector pin 21 can be connected by a high-strength adhesive to ensure that the resistive strain sensor 23 and the retractable ejector pin 21 deform synchronously during the telescopic movement of the retractable ejector pin 21.

[0071] In some embodiments, the retractable ejector pin may include: a housing, a supporting member embedded in the housing and partially protruding, and an elastic member disposed in the housing and acting on the supporting member. The elastic member is associated with the resistive strain sensor. Exemplarily, the supporting member includes a supporting part and a connecting rod connected to the supporting part. The elastic member is a compression spring sleeved on the connecting rod. The supporting member will change its position under the action of the wafer thinning sheet and the elastic member.

[0072] In some embodiments, the retractable ejector pin is an ejector pin made of an elastic material. The ejector pin made of an elastic material will deform under the action of the wafer thinning sheet.

[0073] The resistive strain sensor 23 (Strain Gauge Type Transducer) is a resistive sensor with a resistive strain gauge as the conversion element. In some embodiments, the resistive strain sensor may include an elastic sensitive element, a resistive strain gauge, a compensating resistor, a housing, etc., and can be designed into various structural forms according to specific measurement requirements. The elastic sensitive element is deformed by the measured force, and the resistive strain gauge attached thereto is deformed together. The resistive strain gauge then converts the deformation into a change in resistance value, so that various physical quantities such as pressure, torque, and displacement can be measured. Therefore, in the embodiments of the present disclosure, by obtaining the change in the resistance value of the resistive strain sensor 23, the change in the pressure exerted on it by the retractable ejector pin 21 can be measured, and then the condition of the wafer thinning sheet supported by the retractable ejector pin 21 can be determined.

[0074] To obtain the change in the resistance value in each resistive strain sensor 23, in the embodiments of the present disclosure, the resistive strain sensors in multiple stress monitoring components are connected in combination to construct a strain monitoring circuit. Using the constructed strain monitoring circuit, the measured data of the electrical parameters related to the resistive strain sensors in each stress monitoring component are obtained.

[0075] In some embodiments, the resistive strain sensors in the plurality of stress monitoring components are combined and connected in parallel to construct a constant-voltage shunt-type strain monitoring circuit, forming a circuit structure as shown in Figure 4 the figure.

[0076] In some embodiments, the resistive strain sensors in the plurality of stress monitoring components are combined and connected in series to construct a constant-current voltage-dividing type strain monitoring circuit, forming a circuit structure as shown in Figure 5 the figure.

[0077] Step S203: Obtain the measured data of the electrical parameters related to the resistive strain sensors in each stress monitoring component in the strain monitoring circuit.

[0078] As described above, in some embodiments, the resistive strain sensors in the plurality of stress monitoring components are combined and connected in parallel to construct a constant-voltage shunt-type strain monitoring circuit. Therefore, obtaining the measured data of the electrical parameters related to the resistive strain sensors in each stress monitoring component in the strain monitoring circuit includes: obtaining the measured current signals related to the resistive strain sensors in each stress monitoring component in the constant-voltage shunt-type strain monitoring circuit. Since the resistive strain sensors in the plurality of stress monitoring components are combined and connected in parallel to construct a constant-voltage shunt-type strain monitoring circuit, that is, the resistive strain sensor in each stress monitoring component can form a branch in the constant-voltage shunt-type strain monitoring circuit, and multiple branches are parallel to each other and have the same voltage. In a constant-voltage circuit, the magnitude of the current is inversely proportional to the resistance value of the resistive strain sensor. Therefore, when the resistance values of the resistive strain sensors in each branch change, it can be achieved by detecting the current values corresponding to the measured current signals in each branch.

[0079] As described above, in some embodiments, the resistive strain sensors in the plurality of stress monitoring components are combined and connected to construct a strain monitoring circuit, which includes: the resistive strain sensors in the plurality of stress monitoring components are combined and connected in series to construct a constant current voltage dividing type strain monitoring circuit; obtaining the measured data of the electrical parameters related to the resistive strain sensors in each stress monitoring component in the strain monitoring circuit includes: obtaining the measured voltage signals related to the resistive strain sensors in each stress monitoring component in the constant current voltage dividing type strain monitoring circuit. Since the resistive strain sensors in the plurality of stress monitoring components are combined and connected in series to construct a constant current voltage dividing type strain monitoring circuit, that is, the current flowing through each resistive strain sensor is a constant current with a certain value. In a constant current circuit, the voltage magnitude is directly proportional to the resistance value of the resistive strain sensor. Therefore, when the resistance values of the resistive strain sensors change, it can be achieved by detecting the voltage values corresponding to the measured voltage signals at both ends of each resistive strain sensor.

[0080] Step S205: By comparing the measured data of the electrical parameters related to the resistive strain sensors in each stress monitoring component with the reference values of the electrical parameters, obtain the change amount and change distribution characteristics of the electrical parameters related to each resistive strain sensor, and accordingly determine whether there are problems such as displacement or warping of the wafer thinning sheet.

[0081] In step S205, the measured data of the electrical parameters related to the resistive strain sensors in each stress monitoring component obtained through step S203 can be compared with the reference values of the electrical parameters related to the resistive strain sensors in each stress monitoring component. According to the comparison results, the change amount and change distribution characteristics of the electrical parameters related to each resistive strain sensor can be obtained, thereby determining whether there are problems such as displacement or warping of the wafer thinning sheet.

[0082] In some embodiments, the stress monitoring method for the wafer thinning sheet further includes the step of creating a reference database of electrical parameters, in which the reference values of the electrical parameters related to each resistive strain sensor are recorded.

[0083] The creation of the reference database of electrical parameters may include the following steps:

[0084] First, place the reference wafer thinning sheet on the wafer heating plate and perform station calibration. Here, the reference wafer thinning sheet is at least a wafer thinning sheet without warping.

[0085] Next, a plurality of telescopic ejector pins in the wafer thinning stress monitoring device are used to support the reference wafer thinning sheet to different detection positions and detect the values of the electrical parameters corresponding to different detection positions. The reference wafer thinning sheet is supported to different detection heights by a plurality of telescopic ejector pins. Each time a detection height is reached, the values of the electrical parameters related to the resistive strain sensors corresponding to each telescopic ejector pin at the detection height are detected. Among them, the values of the electrical parameters related to the resistive strain sensors corresponding to each telescopic ejector pin detected at different detection heights are used as reference values.

[0086] In some embodiments, the resistive strain sensors in the plurality of stress monitoring components are connected in parallel and then combined to construct a constant voltage shunt type strain monitoring circuit. Through the foregoing detection, the current values related to the resistive strain sensors corresponding to each telescopic ejector pin at different detection heights can be detected.

[0087] In some embodiments, the resistive strain sensors in the plurality of stress monitoring components are connected in series and then combined to construct a constant current voltage division type strain monitoring circuit. Through the foregoing detection, the voltage values related to the resistive strain sensors corresponding to each telescopic ejector pin at different detection heights can be detected.

[0088] Finally, according to the obtained different detection positions and the values of the electrical parameters corresponding thereto, an electrical parameter reference database is created.

[0089] Therefore, in step S205, the measured data of the electrical parameters related to the resistive strain sensors in each stress monitoring component obtained through step S203 are compared with the reference values of the electrical parameters related to the resistive strain sensors in each stress monitoring component, and the change amount of the electrical parameters related to each resistive strain sensor and the change distribution characteristics of the electrical parameters related to each resistive strain sensor are obtained. According to the change amount and change distribution characteristics of the electrical parameters related to each resistive strain sensor, it is determined whether there are problems such as displacement or warping of the wafer thinning sheet.

[0090] In the constant-voltage shunt-type strain monitoring circuit, when the pressure on the top support part of the telescopic thimble in a certain stress monitoring component decreases due to the pressure of the wafer thinning sheet, the telescopic thimble will extend and drive the resistive strain sensor at the bottom to stretch. After being stretched, the length of the resistive strain sensor increases and the cross-sectional area decreases, resulting in an increase in the resistance value. The measured current value related to the resistive strain sensor becomes smaller, that is, the measured current value related to the resistive strain sensor is less than the reference value of the current parameter. For example, when the wafer thinning sheet corresponding to the top support part of the telescopic thimble in a certain stress monitoring component warps upward or the wafer thinning sheet shifts away, the pressure on the top support part of the telescopic thimble in the stress monitoring component will decrease, the resistance value of the resistive strain sensor will increase, and in the case of constant voltage, the measured current value related to the resistive strain sensor will become smaller, which is smaller than the reference value of the current parameter. For specific details, please refer to Figure 6 the rightmost telescopic thimble in

[0091] In the constant-voltage shunt-type strain monitoring circuit, when the pressure on the top support part of the telescopic thimble in a certain stress monitoring component increases due to the pressure of the wafer thinning sheet, the telescopic thimble will contract and drive the resistive strain sensor at the bottom to compress. After being compressed, the length of the resistive strain sensor decreases and the cross-sectional area increases, resulting in a decrease in the resistance value. The measured current value related to the resistive strain sensor becomes larger, that is, the measured current value related to the resistive strain sensor is greater than the reference value of the current parameter. For example, when the wafer thinning sheet corresponding to the top support part of the telescopic thimble in a certain stress monitoring component warps downward or the wafer thinning sheet shifts closer, the pressure on the top support part of the telescopic thimble in the stress monitoring component will increase, the resistance value of the resistive strain sensor will decrease, and in the case of constant voltage, the measured current value related to the resistive strain sensor will become larger, which is larger than the reference value of the current parameter. For specific details, please refer to Figure 7 the rightmost telescopic thimble in

[0092] Similarly, in the constant current voltage dividing type strain monitoring circuit, when the pressure on the supporting part of the retractable thimble in a certain stress monitoring component decreases due to the pressure of the wafer thinning sheet, the retractable thimble will extend and drive the resistive strain sensor at the bottom to stretch. After being stretched, the length of the resistive strain sensor increases and the cross-sectional area decreases, resulting in an increase in the resistance value. The measured voltage value related to the resistive strain sensor becomes larger, that is, the measured voltage value related to the resistive strain sensor is greater than the reference value of the voltage parameter. For example, when the wafer thinning sheet corresponding to the supporting part of the retractable thimble in a certain stress monitoring component warps upward or the wafer thinning sheet shifts away, the pressure on the supporting part of the retractable thimble in the stress monitoring component will decrease, the resistance value of the resistive strain sensor will increase, and in the case of constant current, the measured voltage value related to the resistive strain sensor will become larger, which is larger than the reference value of the voltage parameter. For details, please refer to Figure 8 the rightmost retractable thimble in

[0093] In the constant current voltage dividing type strain monitoring circuit, when the pressure on the supporting part of the retractable thimble in a certain stress monitoring component increases, the retractable thimble will contract and drive the resistive strain sensor at the bottom to compress. After being compressed, the length of the resistive strain sensor decreases and the cross-sectional area increases, resulting in a decrease in the resistance value. The measured voltage value related to the resistive strain sensor becomes smaller, that is, the measured voltage value related to the resistive strain sensor is less than the reference value of the voltage parameter. For example, when the wafer thinning sheet corresponding to the supporting part of the retractable thimble in a certain stress monitoring component warps downward or the wafer thinning sheet shifts closer, the pressure on the supporting part of the retractable thimble in the stress monitoring component will increase, the resistance value of the resistive strain sensor will decrease, and in the case of constant current, the measured voltage value related to the resistive strain sensor will become smaller, which is smaller than the reference value of the voltage parameter. For details, please refer to Figure 9 the rightmost retractable thimble in

[0094] Thus, through the above stress monitoring method for the wafer thinning sheet, the measured data of the electrical parameters related to the resistive strain sensors in each stress monitoring component are obtained through the strain monitoring circuit. According to the change of the measured data compared with the reference value, it can be determined whether there are problems of displacement or warping of the wafer thinning sheet. For example, when the measured data of the electrical parameters related to the resistive strain sensors in each stress monitoring component change compared with the reference value of their corresponding electrical parameters and the change exceeds the set threshold, it can be determined that there are problems of displacement or warping of the wafer thinning sheet. Subsequently, corresponding adjustment measures can be taken according to the problems of displacement or warping of the wafer thinning sheet. For example, if the wafer thinning sheet is displaced, the working station of the wafer thinning sheet can be calibrated to adjust the wafer thinning sheet to the reference position. If the wafer thinning sheet is warped, the process parameters of the wafer thinning sheet can be adjusted, such as the heating problem of the heating plate, the flow rate of the filled gas, the power of the plasma generator, etc.

[0095] From the analysis of the above various situations, it can be seen that when the wafer is warped or displaced, it can be verified by the current change amount obtained by comparing the measured current value of the detected resistive strain sensor in the constant voltage shunt type strain monitoring circuit with the corresponding reference current value, or by the voltage change amount obtained by comparing the measured voltage value of the detected resistive strain sensor in the constant current voltage division type strain monitoring circuit with the corresponding reference voltage value.

[0096] However, it cannot be determined whether the wafer thinning sheet has a warping problem or a displacement problem only by the current change amount of a single resistive strain sensor in the constant voltage shunt type strain monitoring circuit or the voltage change amount in the constant current voltage division type strain monitoring circuit. Therefore, in the embodiments of the present disclosure, an overall electrical parameter analysis is performed on each stress monitoring component in the wafer thinning sheet stress monitoring device for determination, that is, by comparing the measured data of the electrical parameters related to the resistive strain sensors in each stress monitoring component with the reference value of the electrical parameters, the change amount and change distribution characteristics of the electrical parameters related to each resistive strain sensor are obtained, and based on this, it is determined whether there are problems of displacement or warping of the wafer thinning sheet.

[0097] Taking the constant voltage shunt type strain monitoring circuit as an example, by comparing the measured current value of the resistive strain sensor in each stress monitoring component with the corresponding current reference value, the current change amount in each resistive strain sensor and the current change distribution characteristics of each resistive strain sensor are obtained, and based on this, it is determined whether there are problems of displacement or warping of the wafer thinning sheet.

[0098] In some embodiments, if the current change distribution characteristics in each resistive strain sensor show that the current value of a single or individual resistive strain sensor has changed and the current change amount exceeds the current threshold set according to the process requirements, while the current values of other resistive strain sensors have not changed or have changed but the current change amount does not exceed the current threshold, it can be determined that the wafer thinning sheet has a warping problem or the probability of the wafer thinning sheet having a warping problem is relatively high and the probability of having a shifting problem is relatively low.

[0099] In some embodiments, if the distribution characteristics of the current changes in each resistive strain sensor show that the current values of all resistive strain sensors have changed and most or all of the current change amounts exceed the current threshold set according to the process requirements, it can be determined that the wafer thinning sheet has a shifting problem or the probability of the wafer thinning sheet having a shifting problem is relatively high and the probability of having a warping problem is relatively low.

[0100] Taking the constant current voltage division type strain monitoring circuit as an example, by comparing the measured voltage values of the resistive strain sensors in each stress monitoring component with the corresponding voltage reference values, the voltage change amounts in each resistive strain sensor and the voltage change distribution characteristics of each resistive strain sensor are obtained, and based on this, it is determined whether the wafer thinning sheet has a shifting or warping problem.

[0101] In some embodiments, if the voltage change distribution characteristics in each resistive strain sensor show that the voltage value of a single or individual resistive strain sensor has changed and the voltage change amount exceeds the voltage threshold set according to the process requirements, while the voltage values of other resistive strain sensors have not changed or have changed but the voltage change amount does not exceed the voltage threshold, it can be determined that the wafer thinning sheet has a warping problem or the probability of the wafer thinning sheet having a warping problem is relatively high and the probability of having a shifting problem is relatively low.

[0102] In some embodiments, if the voltage change distribution characteristics in each resistive strain sensor show that the voltage values of all resistive strain sensors have changed and most or all of the voltage change amounts exceed the voltage threshold set according to the process requirements, it can be determined that the wafer thinning sheet has a shifting problem or the probability of the wafer thinning sheet having a shifting problem is relatively high and the probability of having a warping problem is relatively low.

[0103] In some embodiments, an electrical parameter analysis model may also be provided. The measured data of the electrical parameters related to the resistive strain sensors in each of the detected stress monitoring components and the reference values of the electrical parameters are input into the electrical parameter analysis model. Alternatively, the change amounts and change distribution characteristics of the electrical parameters related to each resistive strain sensor obtained by comparing the measured data of the electrical parameters related to the resistive strain sensors in each stress monitoring component with the reference values of the electrical parameters are input into the electrical parameter analysis model. The electrical parameter analysis model determines whether there are problems of displacement or warping of the wafer thinning sheet based on the change amounts and change distribution characteristics of the electrical parameters related to each resistive strain sensor. In some applications, the electrical parameter analysis model may be constructed based on a machine learning model and obtained through training. As an example, the machine learning model may be implemented as a neural network model. The neural network model may be implemented to include an input layer, multiple hidden layers, and an output layer. The input layer may include one or more input nodes (determined according to the number of input parameters). Each of the hidden layers may include multiple hidden nodes connected to the nodes in the previous layer. The output layer includes one or more output nodes (determined according to the number of output parameters) and is connected to the hidden nodes in the last hidden layer. The nodes from the front to the back are connected by branch lines. Each branch line corresponds to a weight. Each hidden node may have an offset value. The hidden node calculates the input of each branch line (such as calculating the weighted sum), adds the offset value, and outputs it to the next-level node (hidden node or output node), and finally forms an output at the output node.

[0104] As an example, the machine learning model includes, but is not limited to, neural networks, such as, for example, generative adversarial network (GAN), region-based convolutional neural network (R-CNN), region proposal network (RPN), recurrent neural network (RNN), stacked deep neural network (S-DNN), state space dynamic neural network (S-SDNN), deconvolution network, deep belief network (DBN), restricted Boltzmann machine (RBM), fully convolutional network, long short-term memory (LSTM) network, etc. Optionally or additionally, the machine learning model may include other forms including an ensemble such as random forest, such as, for example, linear and / or logistic regression, statistical clustering, Bayesian classification, decision tree, dimensionality reduction (such as principal component analysis PCA), and expert systems and / or combinations thereof.

[0105] The following combines the accompanying drawings to describe in detail the application of the above stress monitoring method for the wafer thinning sheet in the actual process, specifically as follows:

[0106] Please refer to Figure 10, there are four monitoring points on the wafer heating plate 11. These four monitoring points form a square at an interval of 90° and are all on the circumference of a formed monitoring circle. The monitoring points can be, for example, detection holes penetrating the wafer heating plate 11.

[0107] The telescopic ejector pins in the stress monitoring assembly are correspondingly inserted through the detection holes on the wafer heating plate 11. After the telescopic ejector pins are inserted into the detection holes, the supporting parts of the telescopic ejector pins protrude from the upper side of the wafer heating plate 11. In this way, the multiple supporting parts protruding from the wafer heating plate 11 among the four telescopic ejector pins can form a supporting surface for supporting the wafer thinning sheet 100. In Figure 10 , the telescopic ejector pins at the four monitoring points can be respectively marked as P1, P2, P3, and P4.

[0108] A resistive strain sensor (not shown in the figure) is connected to the bottom of each telescopic ejector pin 21. Among them, the resistive strain sensors in the multiple stress monitoring assemblies are combined and connected in parallel to construct a constant-voltage shunt-type strain monitoring circuit, or the resistive strain sensors in the multiple stress monitoring assemblies are combined and connected in series to construct a constant-current voltage-dividing type strain monitoring circuit.

[0109] Taking the constant-voltage shunt-type strain monitoring circuit as an example:

[0110] Create an electrical parameter reference database: First, place the reference wafer thinning sheet on the wafer heating plate and perform station calibration. Then, use the multiple telescopic ejector pins in the wafer thinning sheet stress monitoring device to support the reference wafer thinning sheet to different detection heights and detect the current values corresponding to different detection heights; according to the obtained different detection heights and their corresponding current values, create a current reference database corresponding to the constant-voltage shunt-type strain monitoring circuit, where the current values detected at different detection heights are used as reference current values.

[0111] Figure 11 It is shown as a schematic diagram of the current-time change corresponding to when the multiple telescopic ejector pins support the reference wafer thinning sheet to a certain detection height, as Figure 11 shown. The resistance values of the resistive strain sensors connected to the respective telescopic ejector pins P1, P2, P3, and P4 are stable at a certain detection height. Therefore, the performance of their current values I1, I2, I3, and I4 is also stable (as Figure 11As shown, the current value of the resistive strain sensor is stable at 0.3 A, and these current values can be used as the reference current values for judging the wafer thinning sheet at a certain detection height. Therefore, if a plurality of retractable thimbles in the wafer thinning sheet stress monitoring device are used to support the reference wafer thinning sheet to different detection heights, the resistance values of the resistive strain sensors connected to the retractable thimbles at different detection heights can be obtained corresponding to the reference current values. In this way, according to the obtained different detection positions and their corresponding reference current values, a current reference database is created.

[0112] In some embodiments, if the wafer thinning sheet warps, for example, please refer to Figure 11 , a part of the wafer thinning sheet corresponding to the retractable thimble P1 warps, and the pressure on the supporting part of the retractable thimble P1 by the wafer thinning sheet becomes smaller, then the resistance value of the resistive strain sensor R1 corresponding to the retractable thimble P1 increases, and the measured current value I1 related to the resistive strain sensor R1 becomes smaller, for example, 0.2 A; if other parts of the wafer thinning sheet do not warp, then the measured current values I2, I3, I4 related to the resistive strain sensors R2, R3, R4 corresponding to the other retractable thimbles P2, P3, P4 still remain at 0.3 A.

[0113] In some embodiments, if the wafer thinning sheet is displaced, for example, please refer to Figure 11 , the wafer thinning sheet is displaced towards the retractable thimble P4, and the pressure on the supporting part of the retractable thimble P4 by the wafer thinning sheet becomes larger, then the resistance value of the resistive strain sensor R4 corresponding to the retractable thimble P4 decreases, and the measured current value I4 related to the resistive strain sensor R4 becomes larger, for example, 0.45 A; the other retractable thimbles will also change due to the displacement of the wafer thinning sheet. For example, the pressure on the supporting part of the retractable thimble P1 by the wafer thinning sheet becomes smaller, then the resistance value of the resistive strain sensor R1 corresponding to the retractable thimble P1 increases, and the measured current value I1 related to the resistive strain sensor R1 becomes smaller, for example, 0.25 A; the pressure on the supporting parts of the retractable thimbles P2, P3 by the wafer thinning sheet becomes larger (or smaller), then the resistance values of the resistive strain sensors R2, R3 corresponding to the retractable thimbles P2, P3 decrease (or increase), and the measured current values I2, I3 related to the resistive strain sensors R2, R3 become larger (or smaller), for example, 0.35 A (or 0.25 A).

[0114] Taking the constant current voltage division type strain monitoring circuit as an example:

[0115] Create an electrical parameter reference database: First, place the reference wafer thin slice on the wafer heating plate and perform station calibration. Then, use multiple retractable thimbles in the reference wafer thin slice stress monitoring device to lift the reference wafer thin slice to different detection heights and detect the voltage values corresponding to different detection heights. According to the obtained different detection heights and their corresponding voltage values, create a voltage reference database corresponding to the constant current voltage division type strain monitoring circuit, where the voltage values detected at different detection heights are used as the reference voltage values.

[0116] Figure 12 It shows a schematic diagram of the voltage-time change corresponding to when the reference wafer thin slice is lifted to a certain detection height by multiple retractable thimbles, as Figure 12 shown. The resistance values of the resistive strain sensors connected to each retractable thimble P1, P2, P3, P4 are stable at a certain detection height. Therefore, their voltage values V1, V2, V3, V4 are also stable (as Figure 12 shown, the voltage value of the detected resistive strain sensor is stable at 3 volts). These voltage values can be used as the reference voltage values for judging the reference wafer thin slice at a certain detection height. Therefore, if the reference wafer thin slice is lifted to different detection heights by multiple retractable thimbles in the reference wafer thin slice stress monitoring device, the reference voltage values corresponding to the resistance values of the resistive strain sensors connected to the retractable thimbles at different detection heights can be obtained. In this way, according to the obtained different detection positions and their corresponding reference voltage values, a voltage reference database is created.

[0117] In some embodiments, if the reference wafer thin slice warps, for example, please refer to Figure 12 , a part of the reference wafer thin slice corresponding to the retractable thimble P1 warps. The pressure on the lifting part of the retractable thimble P1 from the reference wafer thin slice becomes smaller, so the resistance value of the resistive strain sensor R1 corresponding to the retractable thimble P1 increases, and the measured voltage value V1 related to the resistive strain sensor R1 becomes larger, for example, 3.5 volts. If other parts of the reference wafer thin slice do not warp, the measured voltage values V2, V3, V4 related to the resistive strain sensors R2, R3, R4 corresponding to the other retractable thimbles P2, P3, P4 still remain at 3 volts.

[0118] In some embodiments, if the reference wafer thin slice shifts, for example, please refer to Figure 12, the wafer thinning sheet shifts towards the retractable thimble P4, and the pressure on the supporting part of the retractable thimble P4 from the wafer thinning sheet increases. Then, the resistance value of the resistive strain sensor R4 corresponding to the retractable thimble P4 decreases, and the measured voltage value V4 related to the resistive strain sensor R4 becomes smaller, for example, 2 volts. Other retractable thimbles will also change due to the shift of the wafer thinning sheet. For example, the pressure on the supporting part of the retractable thimble P1 from the wafer thinning sheet decreases, then the resistance value of the resistive strain sensor R1 corresponding to the retractable thimble P1 increases, and the measured voltage value V1 related to the resistive strain sensor R1 becomes larger, for example, 4 volts. The pressure on the supporting parts of the retractable thimbles P2 and P3 from the wafer thinning sheet increases (or decreases), then the resistance values of the resistive strain sensors R2 and R3 corresponding to the retractable thimbles P2 and P3 decrease (or increase), and the measured voltage values V2 and V3 related to the resistive strain sensors R2 and R3 become smaller (or larger), for example, 2.5 volts (or 3.5 volts).

[0119] In the method for monitoring the stress of the wafer thinning sheet in the present disclosure, it may further include overall analyzing the measured data of the electrical parameters related to the resistive strain sensors in each stress monitoring component to evaluate whether the wafer thinning sheet with a displacement or warping problem is more likely to have a displacement problem or a warping problem.

[0120] In some embodiments, by comparing the measured data of the electrical parameters related to the resistive strain sensors in the obtained multiple stress monitoring components with their respective reference values of the electrical parameters, if it is found that only one or a few measured data of the electrical parameters related to the resistive strain sensors change and the change amount exceeds the set threshold while the measured data of the electrical parameters related to several other resistive strain sensors do not change or the change amount does not exceed the set threshold, then it can be evaluated that the wafer thinning sheet is more likely to have a warping problem. Subsequently, the process parameters of the wafer thinning sheet can be adjusted, for example, the heating problem of the heating plate, the flow rate of the filled gas, the power of the plasma generator, etc.

[0121] In some embodiments, by comparing the measured data of the electrical parameters related to the resistive strain sensors in the obtained multiple stress monitoring components with their respective reference values of the electrical parameters, if it is found that all or most of the measured data of the electrical parameters related to the resistive strain sensors change and the change amount exceeds the set threshold, then it can be evaluated that the wafer thinning sheet is more likely to have a displacement problem and the position of which one (or some) of the wafer thinning sheet has a displacement can be roughly determined. Subsequently, the station calibration can be performed on the wafer thinning sheet to adjust the wafer thinning sheet to the reference position.

[0122] The present disclosure provides a method for stress monitoring of a wafer thinning sheet. By providing a stress monitoring device for the wafer thinning sheet, a plurality of stress monitoring components are respectively arranged at a plurality of monitoring points of a wafer heating plate. The resistive strain sensors in the plurality of stress monitoring components are combined and connected to construct a strain monitoring circuit. In this way, the measured data of the electrical parameters related to the resistive strain sensors in each stress monitoring component can be obtained according to the strain monitoring circuit. By comparing the measured data of the electrical parameters related to the resistive strain sensors in each stress monitoring component with the reference value of the electrical parameters, the change amount and change distribution characteristics of the electrical parameters related to each resistive strain sensor can be obtained, and based on this, it can be determined whether there are problems such as displacement or warping of the wafer thinning sheet. Compared with the related art, the stress monitoring method for the wafer thinning sheet provided by the present disclosure has a simple process, does not affect the semiconductor process, has accurate detection, and when it is detected that there is displacement or warping of the wafer thinning sheet, taking corresponding adjustment measures is beneficial to the subsequent semiconductor wafer manufacturing process and improves the yield.

[0123] Another embodiment of the present disclosure provides a stress monitoring and control device for a wafer thinning sheet, which is applied to semiconductor process equipment. Taking the semiconductor process equipment as a wafer degumming equipment as an example, the wafer degumming equipment may include a degumming cavity, a wafer heating plate, at least one gas inlet device, and an exhaust device.

[0124] Please refer to Figure 13 , which shows the principle block diagram of the stress monitoring and control device for the wafer thinning sheet provided by the present disclosure in an embodiment.

[0125] As Figure 13 shown, the stress monitoring and control device 3 for the wafer thinning sheet includes a processor 31 and a memory 33. The processor 31 and the memory 33 can communicate through a bus 32. The memory 33 may store a stress monitoring program for the wafer thinning sheet. The processor 31 executes each step in the stress monitoring method for the wafer thinning sheet by running the internal leakage detection program in the memory 33.

[0126] The bus 32 may be a Peripheral Component Interconnect (PCI) bus or an Extended Industry Standard Architecture (EISA) bus, etc. The bus can be divided into an address bus, a data bus, a control bus, etc. For the convenience of representation, although only a thick line is used in the figure, it does not mean that there is only one bus or one type of bus.

[0127] In some embodiments, the processor 31 may be implemented as a Central Processing Unit (CPU), a Micro Controller Unit (MCU), a System on Chip (SoC), a Field Programmable Gate Array (FPGA), or the like. The memory 33 may include volatile memory for temporarily storing data when running a program, such as Random Access Memory (RAM). The memory 33 may also include non-volatile memory (Non-Volatile Memory; NVM) for data storage, such as Read-Only Memory (ROM), flash memory, a Hard Disk Drive (HDD), or a Solid-State Disk (SSD).

[0128] An embodiment of the present disclosure may also provide a computer-readable storage medium storing a computer program or instructions, which when run implement the method flow or function in any of the previous embodiments.

[0129] That is, the method steps in the above embodiments are implemented as software or computer code that can be stored in a recording medium (such as a CD ROM, RAM, floppy disk, hard disk, or magneto-optical disk), or are implemented as computer code originally stored in a remote recording medium or a non-transitory machine-readable medium and downloaded through a network and to be stored in a local recording medium, so that the method represented herein can be stored on such a recording medium and processed by such software using a general-purpose computer, a dedicated processor, or programmable or dedicated hardware (such as an ASIC or an FPGA).

[0130] An embodiment of the present disclosure may also provide a computer program product including one or more computer programs or instructions, which when run fully or partially execute the process or function in the embodiments of the present disclosure. The computer program product includes one or more computer programs or instructions.

[0131] Computer programs or instructions can be stored in a readable storage medium or transmitted from one readable storage medium to another. For example, the computer programs or instructions can be transmitted from one website, computer, server, or data center to another website, computer, server, or data center in a wired or wireless manner. The readable storage medium can be any available medium that can be accessed or a data storage device such as a server or data center integrating one or more available media. The available medium can be a magnetic medium, such as a floppy disk, hard disk, or magnetic tape; it can also be an optical medium, such as a digital video disc; or it can be a semiconductor medium, such as a solid state drive. The computer-readable storage medium can be a volatile or non-volatile storage medium, or can include both volatile and non-volatile types of storage media.

[0132] The above embodiments are only illustrative of the principles and effects of the present disclosure and are not intended to limit the present disclosure. Any person familiar with this technology can modify or change the above embodiments without departing from the spirit and scope of the present disclosure. Therefore, all equivalent modifications or changes made by those with ordinary knowledge in the technical field without departing from the spirit and technical ideas disclosed by the present disclosure should still be covered by the protection scope of the present disclosure.

Claims

1. A method for monitoring stress of a wafer thinning film, characterized in that: Applied in semiconductor process equipment, the stress monitoring method for wafer thinning comprises the following steps: A wafer thinning sheet stress monitoring device is provided, and the wafer thinning sheet stress monitoring device is configured in a semiconductor process equipment; the wafer thinning sheet stress monitoring device includes a plurality of stress monitoring components, which are arranged at a plurality of monitoring points of a wafer heating plate in a one-to-one correspondence; Each stress monitoring assembly includes a retractable ejector pin, the retractable ejector pin having a supporting portion for supporting a wafer thinning sheet and a bottom portion opposite to the supporting portion, and a resistive strain sensor is connected to the bottom of the retractable ejector pin; the resistive strain sensors in the multiple stress monitoring assemblies are combined and connected to form a strain monitoring circuit; Obtaining measured data of electrical parameters related to resistive strain sensors in each stress monitoring component in the strain monitoring circuit; By comparing the measured data of the electrical parameters related to the resistive strain sensors in each stress monitoring component with the reference values ​​of the electrical parameters, the change amount and change distribution characteristics of the electrical parameters related to each resistive strain sensor are obtained, and it is determined whether the wafer thinning sheet has a displacement or warping problem; wherein the reference values ​​of the electrical parameters are determined by supporting the reference wafer thinning sheet to different detection heights through multiple retractable ejectors, and detecting the electrical parameter values ​​related to the resistive strain sensors corresponding to the multiple retractable ejectors at each detection height.

2. The method for monitoring stress of a wafer thinning sheet according to claim 1, characterized in that: The resistive strain sensors in the multiple stress monitoring components are connected in combination to form a strain monitoring circuit, including: the resistive strain sensors in the multiple stress monitoring components are connected in combination in parallel to form a constant voltage shunt strain monitoring circuit; the obtaining of measured data of electrical parameters related to the resistive strain sensors in each stress monitoring component in the strain monitoring circuit includes: obtaining measured current signals related to the resistive strain sensors in each stress monitoring component in the constant voltage shunt strain monitoring circuit; or, the resistive strain sensors in the multiple stress monitoring components are connected in combination to form a strain monitoring circuit, including: the resistive strain sensors in the multiple stress monitoring components are connected in series to form a constant current voltage-dividing strain monitoring circuit; the obtaining of measured data of electrical parameters related to the resistive strain sensors in each stress monitoring component in the strain monitoring circuit includes: obtaining measured voltage signals related to the resistive strain sensors in each stress monitoring component in the constant current voltage-dividing strain monitoring circuit.

3. The method for monitoring stress of a wafer thinning film according to claim 2, characterized in that: In the constant-voltage shunt strain monitoring circuit, when the supporting portion of the retractable ejector pin in a certain stress monitoring component is subjected to a smaller pressure from the wafer thinning sheet, the ejector pin will extend and drive the resistive strain sensor at the bottom to stretch. After being stretched, the length of the resistive strain sensor increases and the cross-sectional area decreases, resulting in an increase in resistance, and the measured current value associated with the resistive strain sensor decreases, that is, the measured current value associated with the resistive strain sensor is less than the reference value of the current parameter; when the supporting portion of the retractable ejector pin in a certain stress monitoring component is subjected to a larger pressure from the wafer thinning sheet, the ejector pin will contract and drive the resistive strain sensor at the bottom to compress. After being compressed, the length of the resistive strain sensor decreases and the cross-sectional area increases, resulting in a decrease in resistance, and the measured current value associated with the resistive strain sensor increases, that is, the measured current value associated with the resistive strain sensor is greater than the reference value of the current parameter; or In the constant current voltage-dividing strain monitoring circuit, when the supporting portion of the retractable ejector pin in a certain stress monitoring component is subjected to a smaller pressure from the wafer thinning sheet, the ejector pin will extend and drive the resistive strain sensor at the bottom to stretch. After being stretched, the length of the resistive strain sensor increases and the cross-sectional area decreases, resulting in an increase in resistance value, and the measured voltage value associated with the resistive strain sensor increases, that is, the measured voltage value associated with the resistive strain sensor is greater than the reference value of the voltage parameter; when the supporting portion of the retractable ejector pin in a certain stress monitoring component is subjected to a larger pressure from the wafer thinning sheet, the ejector pin will contract and drive the resistive strain sensor at the bottom to compress. After being compressed, the length of the resistive strain sensor decreases and the cross-sectional area increases, resulting in a decrease in resistance value, and the measured voltage value associated with the resistive strain sensor decreases, that is, the measured voltage value associated with the resistive strain sensor is less than the reference value of the voltage parameter.

4. The method for monitoring stress of a wafer thinning sheet according to claim 1, further comprising the step of creating an electrical parameter reference database, wherein the reference values ​​of electrical parameters related to each resistive strain sensor are recorded in the electrical parameter reference database; the step of creating the electrical parameter reference database comprises the following steps: Place the reference wafer thinning sheet on the wafer heating plate and perform station calibration; Using a plurality of retractable ejectors in a wafer thinning sheet stress monitoring device to lift the reference wafer thinning sheet to different detection positions and detect the values ​​of electrical parameters corresponding to the different detection positions; An electrical parameter reference database is created based on the different detection positions obtained and the values ​​of the electrical parameters corresponding thereto.

5. A wafer thinning stress monitoring device, characterized in that: Applied in semiconductor process equipment, the wafer thinning sheet stress monitoring device comprises: a plurality of stress monitoring components, which are arranged one by one at a plurality of monitoring points of a wafer heating plate; each stress monitoring component comprises a retractable ejector pin, the retractable ejector pin having a supporting portion for supporting the wafer thinning sheet and a bottom opposite to the supporting portion, and a resistive strain sensor is connected to the bottom of the retractable ejector pin; the resistive strain sensors in the plurality of stress monitoring components are combined and connected to form a strain monitoring circuit; the strain monitoring circuit is used to obtain the corresponding strain signals of the resistive strain sensors in each stress monitoring component. The measured data of the electrical parameters related to the resistive strain sensors in each stress monitoring component are obtained by comparing the measured data of the electrical parameters related to the resistive strain sensors in each stress monitoring component with the reference values ​​of the electrical parameters to obtain the change amount and change distribution characteristics of the electrical parameters related to each resistive strain sensor, so as to determine whether there is a problem of displacement or warping of the wafer thinning sheet; wherein the reference values ​​of the electrical parameters are determined by supporting the reference wafer thinning sheet to different detection heights through a plurality of retractable ejectors, and detecting the electrical parameter values ​​related to the resistive strain sensors corresponding to the plurality of retractable ejectors at each detection height.

6. The wafer thinning stress monitoring device according to claim 5, characterized in that: The resistive strain sensors in the multiple stress monitoring components are combined and connected to form a strain monitoring circuit, including: the resistive strain sensors in the multiple stress monitoring components are combined and connected in parallel to form a constant-voltage shunt-type strain monitoring circuit; or the resistive strain sensors in the multiple stress monitoring components are combined and connected in series to form a constant-current shunt-type strain monitoring circuit.

7. The wafer thinning stress monitoring device according to claim 5, characterized in that: The multiple monitoring points are evenly distributed in the edge area of ​​the wafer heating plate, and the monitoring points are detection holes that penetrate the wafer heating plate. After the retractable ejector pin is inserted into the detection hole, the supporting portion of the retractable ejector pin protrudes from the wafer heating plate.

8. The wafer thinning stress monitoring device according to claim 5, characterized in that: The retractable ejector pin comprises: a shell, a supporting member embedded in the shell and partially exposed, and an elastic member disposed in the shell and acting on the supporting member, wherein the elastic member is associated with the resistive strain sensor; or, the retractable ejector pin is an ejector pin made of elastic material.

9. A semiconductor process equipment, characterized in that: It comprises a wafer thinning stress monitoring device as claimed in any one of claims 5 to 8.

10. A wafer thinning stress monitoring and control device, characterized in that: include: processor; A memory storing a wafer thinning stress monitoring program; Wherein, the wafer thinning sheet stress monitoring is executed by the processor when it is executed. The wafer thinning sheet stress monitoring method according to any one of claims 1 to 4 is performed.

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