Stress monitoring method and monitoring device for wafer thinning sheet, and semiconductor process equipment

Abstract

The invention provides a stress monitoring method and a stress monitoring device for a wafer thinning sheet, and semiconductor process equipment. In the stress monitoring method, a plurality of stress monitoring assemblies are arranged at a plurality of monitoring points of a wafer heating disc in a one-to-one correspondence manner, and resistance-type strain sensors in the plurality of stress monitoring assemblies are combined to construct a strain monitoring circuit; the method comprises the following steps: acquiring actual measurement data of electrical parameters related to each resistance-type strain sensor, and comparing the actual measurement data of the electrical parameters related to each resistance-type strain sensor with a reference value of the actual measurement data to obtain variation and variation distribution characteristics of the electrical parameters related to each resistance-type strain sensor; and judging whether the wafer thinning sheet has the problem of displacement or warping or not. The technical scheme has the advantages that the flow is simple, the semiconductor process is not influenced, the detection is accurate, corresponding adjustment measures are adopted when displacement or warping of the wafer thinning sheet is monitored, the subsequent semiconductor wafer process is facilitated, and the yield is improved.

Description

Technical Field

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

[0002] Photoresist can be used as a medium for pattern conversion from photolithography mask to wafer during photolithography and as a protective film for areas that do not need to be etched during etching. In the wafer manufacturing process, 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. This process is called stripping.

[0003] The methods of photoresist removal mainly include wet photoresist removal and dry photoresist removal. Plasma photoresist removal is common in dry photoresist removal. Taking plasma photoresist removal as an example, when using plasma photoresist removal equipment, high-frequency electromagnetic generation is used to ionize oxygen into plasma under the action of high-frequency electric field. Its oxidizing ability is very strong, and it reacts with photoresist to turn photoresist into volatile substances that can be extracted by the vacuum system, thus achieving the purpose of photoresist removal.

[0004] Wafer thinning sheets are wafers that are thinner than ordinary wafers. Compared with ordinary wafers, wafer thinning sheets have the advantages of reducing the height of the package patch, reducing the chip packaging volume, improving the chip's thermal diffusion efficiency, electrical performance, mechanical properties and reducing the amount of dicing processing. They can be used in the manufacture of various products such as chips, solar cells, and power semiconductor devices. However, due to its light and thin characteristics, wafer thinning sheets are more susceptible to stress during the degumming 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 edge of the wafer thinning sheet warps or shifts, it will have a serious impact on the uniformity of degumming and subsequent processes, thereby adversely affecting the product defect rate and production efficiency of the entire manufacturing process. Summary of the invention

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

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

[0007] 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 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 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 retractable ejector pin; the resistive strain sensors in the plurality of stress monitoring components are combined and connected to form a strain monitoring circuit;

[0008] Obtaining measured data of electrical parameters related to 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 baseline values ​​of the electrical parameters, the change amount and change distribution characteristics of the electrical parameters related to each resistive strain sensor are obtained, thereby determining whether there is a problem of displacement or warping of the wafer thinning sheet.

[0010] In certain examples of the first aspect, 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; obtaining the measured data of electrical parameters related to the resistive strain sensors in each stress monitoring component in the strain monitoring circuit includes: obtaining the measured current signal 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; obtaining the measured data of electrical parameters related to the resistive strain sensors in each stress monitoring component in the strain monitoring circuit includes: obtaining the measured voltage signal related to the resistive strain sensors in each stress monitoring component in the constant current voltage-dividing strain monitoring circuit.

[0011] In certain examples of the first aspect, 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. The reference value of the voltage 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 the resistive strain sensor is stretched, its length increases and its cross-sectional area decreases, resulting in an increase in resistance, 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 the resistive strain sensor is compressed, its length decreases and its cross-sectional area increases, resulting in a decrease in resistance, 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.

[0012] In certain examples of the first aspect, the stress monitoring method of the wafer thinning sheet also includes the step of creating an electrical parameter benchmark database, in which the benchmark values ​​of the electrical parameters related to each resistive strain sensor are recorded; the creation of the electrical parameter benchmark database includes the following steps: placing a benchmark wafer thinning sheet on a wafer heating plate and performing a work station calibration; using multiple retractable pins in a wafer thinning sheet stress monitoring device to lift the benchmark wafer thinning sheet to different detection positions and detect the values ​​of the electrical parameters corresponding to the different detection positions; and creating an electrical parameter benchmark database based on the obtained different detection positions and the corresponding electrical parameter values.

[0013] According to a second aspect of the present disclosure, there is provided a wafer thinning sheet stress monitoring device, which is applied to 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, wherein the retractable ejector pin 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 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 measured data of electrical parameters related to the resistive strain sensors in each stress monitoring component, and the measured data of the electrical parameters related to the resistive strain sensors in each stress monitoring component are compared with the reference value 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 the wafer thinning sheet has a displacement or warping problem.

[0014] In certain examples of the second aspect, 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-type strain monitoring circuit; or, the resistive strain sensors in the multiple stress monitoring components are connected in combination in series to form a constant-current shunt-type strain monitoring circuit.

[0015] In certain examples of the second aspect, the multiple monitoring points are evenly distributed in the edge area of ​​the wafer heating plate, the monitoring points are detection holes that penetrate the wafer heating plate, and after the retractable ejector pin is passed through the detection hole, the supporting portion of the retractable ejector pin protrudes from the wafer heating plate.

[0016] In certain examples of the second aspect, the retractable ejector pin includes: a shell, a ejector support member embedded in the shell and partially protruding, an elastic member disposed in the shell and acting on the ejector support member, and the elastic member is associated with the resistive strain sensor; or, the retractable ejector pin is an ejector pin made of elastic material.

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

[0018] A fourth aspect of the present disclosure provides a wafer thinning sheet stress monitoring and control device, comprising: a processor; a memory storing a wafer thinning sheet stress monitoring program; wherein the wafer thinning sheet stress monitoring is executed by the processor when the wafer thinning sheet stress monitoring is executed by the wafer thinning sheet stress monitoring method 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 process equipment, and a stress monitoring control device, which can be used to perform stress monitoring on a wafer thinning sheet. In the stress monitoring method, a wafer thinning sheet stress monitoring device is first provided, and a plurality of stress monitoring components are arranged one by one at a plurality of monitoring points of a wafer heating plate, and the resistive strain sensors in the plurality of stress monitoring components are connected in combination to construct a strain monitoring circuit, and 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, and the measured data of the electrical parameters related to the resistive strain sensors in each stress monitoring component are compared with the reference value of the electrical parameters to obtain the change amount and change distribution characteristics of the electrical parameters related to each resistive strain sensor, and thereby determine whether the wafer thinning sheet has a problem of displacement or warping. Compared with the related art, the stress monitoring method for wafer thinning provided by the present invention has a simple process, will not affect the semiconductor process, has accurate detection, and takes corresponding adjustment measures when displacement or warping of the wafer thinning sheet is detected, which is beneficial to the subsequent process technology of semiconductor chips and improves the yield. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 The diagram shows the structure of a semiconductor process equipment in one embodiment of the present invention, to which the stress monitoring method for wafer thinning is applied.

[0021] Figure 2 The figure shows a schematic flow chart of a method for monitoring stress in a wafer thinning process according to an embodiment of the present invention.

[0022] Figure 3 The diagram shows a state where a stress monitoring device is configured in a semiconductor process equipment.

[0023] Figure 4 The schematic diagram of the circuit structure of a constant-voltage shunt strain monitoring circuit is shown in which resistive strain sensors are connected in parallel in a stress monitoring device configuration.

[0024] Figure 5 The schematic diagram of the circuit structure shows that the resistive strain sensors in the stress monitoring device are connected in series to construct a constant current voltage divider strain monitoring circuit.

[0025] Figure 6 Shown is a schematic diagram of the application of a constant voltage shunt type strain monitoring circuit when a wafer thinning sheet is warped upward or when a wafer thinning sheet is displaced and moved away.

[0026] Figure 7 Shown is a schematic diagram of the application of a constant voltage shunt type strain monitoring circuit when the wafer thinning sheet is warped downward or when the wafer thinning sheet is shifted and close.

[0027] Figure 8 The diagram shows the application of the constant current voltage divider strain monitoring circuit when the wafer thinning sheet is warped upward or when the wafer thinning sheet is shifted and moved away.

[0028] Fig. 9 The diagram shows an application diagram of a constant current voltage divider type strain monitoring circuit when a wafer thinning sheet is warped downward or when a wafer thinning sheet is shifted and brought closer.

[0029] Fig.10 Shown is a top view of a wafer thinning sheet configured in a stress monitoring device.

[0030] Fig.11 Schematic diagram showing the current-time variation in different examples of a constant-voltage shunt strain monitoring circuit constructed by connecting resistive strain sensors in multiple stress monitoring components in parallel.

[0031] Fig.12 Schematic diagram showing voltage-time variation in different examples of a constant current voltage divider strain monitoring circuit constructed by serially connecting resistive strain sensors in multiple stress monitoring components.

[0032] Fig.13 Shown is a functional block diagram of a wafer thinning stress monitoring and control device in one embodiment provided by the present disclosure. DETAILED DESCRIPTION

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

[0034] The following is a detailed description of the embodiments of the present disclosure with reference to the accompanying drawings so that those skilled in the art can easily implement the present disclosure. The present disclosure can be embodied in many different forms and is not limited to the embodiments described herein.

[0035] In the representations of the present disclosure, the reference terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" and the like mean that the specific features, structures, materials or characteristics represented in conjunction 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 may be combined in any one or a group of embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine different embodiments or examples represented in the present disclosure and the features of different embodiments or examples, unless they are mutually contradictory.

[0036] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of the features. In the representation of the present disclosure, "a group" means two or more, unless otherwise clearly and specifically defined.

[0037] In order to clearly describe the present disclosure, components not related to the description are omitted, and the same reference numerals are given to the same or similar components throughout the specification.

[0038] Throughout the specification, when a device is said to be "connected" to another device, this includes not only the case of "direct connection" but also the case of "indirect connection" by placing other elements therebetween. In addition, when a device is said to "include" a certain component, unless otherwise stated, it does not exclude other components, but means that other components may be included.

[0039] Although the terms first, second, etc. are used to represent various elements in this article in some examples, these elements should not be limited by these terms. These terms are only used to distinguish one element from another element. For example, the first interface and the second interface, etc. are represented. Moreover, as used in this article, the singular forms "one", "one" and "the" are intended to also include plural forms, unless there is an opposite indication in the context. It should be further understood that the terms "comprising" and "including" indicate that there are the described features, steps, operations, elements, modules, projects, kinds, and / or groups, but do not exclude the existence, occurrence or addition of one or a group of other features, steps, operations, elements, modules, projects, kinds, and / or groups. The terms "or" and "and / or" used herein are interpreted as inclusive, or mean any one or any combination. Therefore, "A, B or C" or "A, B and / or C" means "any of the following: A; B; C; A and B; A and C; B and C; A, B and C". Only when the combination of elements, functions, steps or operations is inherently mutually exclusive in some way, will there be an exception to this definition.

[0040] The technical terms used herein are only used to refer to specific embodiments and are not intended to limit the present disclosure. The singular form used herein also includes the plural form unless the sentence clearly indicates the contrary meaning. The meaning of "including" used in the specification is to specify 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, all terms, including technical and scientific terms used herein, have the same meaning as those generally understood by those skilled in the art to which the present disclosure belongs. Terms defined in commonly used dictionaries are additionally interpreted as having meanings consistent with relevant technical literature and the message of the present disclosure, and shall not be overly interpreted as ideal or very formal meanings unless defined.

[0042] In the related technologies involving the implementation of semiconductor processes on wafer thinning sheets, wafer thinning sheets are more susceptible to stress during process treatment (for example, debonding process) due to their light and thin characteristics, resulting in edge warping or overall displacement, which will have a serious impact on the uniformity of debonding and subsequent processes, thereby adversely affecting many aspects of the entire manufacturing process, such as product defect rate and production efficiency.

[0043] The embodiment of the present disclosure provides a method for monitoring stress of a wafer thinning sheet, which is used to monitor stress of a wafer thinning sheet used in a semiconductor process equipment, wherein the semiconductor process equipment is used to perform corresponding process treatment on the wafer thinning sheet.

[0044] The wafer thinning sheet is a wafer thinner than the ordinary wafer, and a plurality of wafers are arranged on the wafer thinning sheet. In some embodiments, the wafer thinning sheet can be formed by mechanically thinning an ordinary wafer, wherein the middle portion is thinner and the outer portion can be the same thickness as the ordinary wafer. In some embodiments, the wafer thinning sheet is made by a manufacturing process similar to that of an ordinary wafer.

[0045] In some embodiments, taking the degumming process as an example, during the manufacturing process of the wafer, the wafer thinning sheet will be subjected to process treatments such as etching or ion implantation, after which the wafer thinning sheet will be subjected to a degumming process through a degumming device. The degumming methods mainly include wet degumming and dry degumming. Compared with wet degumming, plasma dry degumming uses high-energy plasma to treat the surface of the photoresist, which is thorough and fast in degumming, does not require the introduction of chemical substances, reduces corrosion and damage to the wafer material, and is the preferred method in the existing degumming process. However, due to its light and thin characteristics, the wafer thinning sheet is susceptible to stress in the degumming 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 degumming process.

[0046] In the following description, the semiconductor process equipment will be taken as a wafer stripping equipment as an example.

[0047] Figure 1 The diagram shows the structure of a semiconductor process equipment in one embodiment of the present invention, to which the stress monitoring method for wafer thinning is applied. Figure 1 The semiconductor process equipment shown in FIG. 1 is a wafer stripping equipment.

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

[0049] The debonding chamber 10 comprises a closed chamber with side walls, and a wafer heating plate 11 is arranged in the central area of ​​the closed chamber.

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

[0051] The nozzle or nozzle assembly is connected to at least one air inlet device for delivering process gas into the debonding chamber 10. Each air inlet device includes an air inlet pipeline, an air source and an air source valve arranged on the air inlet pipeline. The process gas provided by the air source may be, for example, oxygen (O2), nitrogen (N2), etc.

[0052] An inlet and outlet can be opened on the side wall of the debonding chamber 10, and the inlet and outlet can be used to transfer related workpieces, including but not limited to wafers, wafer thinning slices, etc. Generally, a first slit door is provided at the inlet and outlet, and the first slit door can move in the up-down direction or left-right direction relative to the inlet and outlet.

[0053] The wafer heating plate is arranged in the debonding chamber and is used to carry and heat the semiconductor wafer. Figure 1 As shown, the wafer heating plate 11 is arranged in the debonding chamber 10, and is used to carry and heat the wafer thinning sheet 100 to be debonded. In some embodiments, a wafer heating plate 11 is arranged in the debonding chamber 10, and the thin film deposition process is performed on only one wafer at a time in the debonding chamber 10, so the wafer heating plate 11 is located in the center of the debonding chamber 10. In some embodiments, two or more wafer heating plates are arranged in the debonding chamber, and each wafer heating plate is arranged with the axis of the debonding chamber as the center.

[0054] In some embodiments, the wafer heating plate 11 may be associated with a moving component. The moving component may be used to drive the wafer heating plate 11 to move. For example, the moving component may be a lifting component, which may 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 be associated with a rotating device. The rotating device may include a selectable rotating member and a rotating power mechanism, the rotating member may be sealed with the wafer heating plate 11 and the debonding chamber 10, and the selectable power mechanism may 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 debonding chamber. In some embodiments, the exhaust device includes an exhaust pipeline connected to the debonding chamber 10 and an exhaust valve and an exhaust pump arranged on the exhaust pipeline.

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

[0058] The plasma generator can be used to ionize the input gas to generate plasma. The plasma has extremely high energy density and reaction activity under a strong electric field, and can quickly destroy the chemical bonds on the surface of the material, decompose the surface attachments into small molecules or atoms, and oxidize or reduce them, thereby removing the surface attachments, realizing the debonding of the wafer thinning film, and using the exhaust device to discharge the gas and particles generated during the debonding process out of the debonding chamber. Taking oxygen O2 as an example, an air intake device is used to transport an appropriate amount of oxygen O2 into the debonding chamber. After the oxygen O2 is ionized by the plasma generator, a plasma mixed with oxygen ions, free oxygen atoms O*, oxygen molecules and electrons is generated. During this period, the free oxygen atoms O* with strong oxidizing ability react with the photoresist film under the action of high-frequency voltage to produce CO2 and H2O, which are discharged through the exhaust device, thereby realizing debonding.

[0059] When debonding a wafer, the wafer is more susceptible to stress during the debonding process due to its thin and light characteristics, resulting in edge warping or overall displacement. Edge warping or overall displacement will have a serious impact on the uniformity of debonding and subsequent process steps, thereby adversely affecting the product defect rate and production efficiency of the entire manufacturing process. Therefore, it is necessary to monitor the stress of the wafer during the debonding process to detect whether the wafer has warping or displacement problems.

[0060] See also Figure 2 , which is a schematic flow chart of a stress monitoring method for wafer thinning provided by the present disclosure in one embodiment.

[0061] Step S201 , providing a wafer thinning slice stress monitoring device, and configuring the wafer thinning slice stress monitoring device in a semiconductor process equipment.

[0062] In some embodiments, the wafer thinning sheet stress monitoring device includes a plurality of stress monitoring components, which are arranged one by one at a plurality of monitoring points of the wafer heating plate. Each stress monitoring component includes a retractable ejector pin, the retractable ejector pin having a supporting portion for supporting the 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 plurality of stress monitoring components are combined and connected to form a strain monitoring circuit.

[0063] like Figure 3 As 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 that penetrate the wafer heating plate 11. Since the wafer thinning sheet is thinner, it is more likely to warp or shift as a whole at its edge, and the warping or shifting 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 wafer thinning stress monitoring device, the retractable ejector pins 21 in the stress monitoring assembly are correspondingly inserted into the detection holes on the wafer heating plate 11 .

[0065] Exemplarily, four monitoring points may be set at the edge of the wafer heating plate 11, and the four monitoring points are evenly distributed, for example, the four monitoring points form a square at an interval of 90° and are all on the circumference of a monitoring circle formed. Exemplarily, six monitoring points may be set at the edge of the wafer heating plate 11, and the six monitoring points are evenly distributed, for example, the four monitoring points form a regular hexagon at an interval of 60° and are all on the circumference of a monitoring circle formed. Exemplarily, eight monitoring points may be set at the edge of the wafer heating plate 11, and the eight monitoring points are evenly distributed, for example, the four monitoring points form a regular octagon at an interval of 45° and are all on the circumference of a monitoring circle formed. Exemplarily, eight monitoring points may be set at the edge of the wafer heating plate 11, and the eight monitoring points form two groups in a group of four, and the four monitoring points in each group are evenly distributed, for example, the four monitoring points in each group form a square at an interval of 45° and are all on the circumference of a monitoring circle formed, so that the two groups can form two squares of different sizes or two monitoring circles of different diameters.

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

[0067] Wherein, the supporting surface matches the bottom surface of the wafer thinning sheet to be supported. Exemplarily, the bottom surface of the wafer thinning sheet is a plane, and the supporting surface formed by the multiple supporting parts of the multiple retractable ejector pins 21 is a horizontal plane. Exemplarily, the bottom surface of the wafer thinning sheet is concave in the middle relative to the edge, and the supporting surface formed by the multiple supporting parts of the multiple retractable ejector pins 21 is a convex surface convex in the middle, that is, the supporting part of the retractable ejector pin 21 located on the inside is higher than the supporting part of the retractable ejector pin 21 located on the outside.

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

[0069] Exemplarily, the retractable ejector pin 21 may 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 may be connected via a high-strength adhesive to ensure that the resistive strain sensor 23 and the retractable ejector pin 21 are deformed synchronously during the retractable movement of the retractable ejector pin 21 .

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

[0073] The resistive strain sensor 23 (Strain Gauge Type Transducer) is a resistive sensor that uses a resistance strain gauge as a conversion element. In some embodiments, the resistive strain sensor may include an elastic sensitive element, a resistance strain gauge, a compensation resistor and a housing, etc., and can be designed into a variety of structural forms according to specific measurement requirements. The elastic sensitive element is deformed by the measured force, and causes the resistance strain gauge attached thereto to deform together. The resistance 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 embodiment 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] In order to obtain the change in resistance value of each resistive strain sensor 23, in the embodiment of the present disclosure, the resistive strain sensors in multiple stress monitoring components are combined and connected to construct a strain monitoring circuit, and the constructed strain monitoring circuit is used to obtain the measured data of electrical parameters related to the resistive strain sensors in each stress monitoring component.

[0075] In some embodiments, the resistive strain sensors in the plurality of stress monitoring components are connected in parallel to form a constant voltage shunt strain monitoring circuit, forming a Figure 4 The circuit structure shown.

[0076] In some embodiments, the resistive strain sensors in the plurality of stress monitoring components are connected in series to form a constant current voltage-dividing strain monitoring circuit, as shown in FIG. Figure 5The circuit structure shown.

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

[0078] As mentioned above, in some embodiments, the resistive strain sensors in the multiple stress monitoring components are combined and connected in parallel to form a constant voltage shunt strain monitoring circuit. Therefore, the actual 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 actual measured current signal related to the resistive strain sensors in each stress monitoring component in the constant voltage shunt strain monitoring circuit. Since the resistive strain sensors in the multiple stress monitoring components are combined and connected in parallel to form a constant voltage shunt strain monitoring circuit, that is, the resistive strain sensors in each stress monitoring component can constitute a branch in the constant voltage shunt strain monitoring circuit, and multiple branches are parallel to each other and have the same voltage. In the constant voltage circuit, the current size is inversely proportional to the resistance value of the resistive strain sensor. Therefore, when the resistance value of the resistive strain sensor in each branch changes, it can be achieved by detecting the current value corresponding to the actual measured current signal in each branch.

[0079] As mentioned above, in some embodiments, the resistive strain sensors in the multiple stress monitoring components are connected in combination to form a strain monitoring circuit, which includes: 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 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 signal related to the resistive strain sensors in each stress monitoring component in the constant current voltage-dividing strain monitoring circuit. Since the resistive strain sensors in the multiple stress monitoring components are connected in series to form a constant current voltage-dividing strain monitoring circuit, that is, the current flowing through each resistive strain sensor is a constant current with a certain value. In the constant current circuit, the voltage is proportional to the resistance value of the resistive strain sensor. Therefore, when the resistance value of each resistive strain sensor changes, it can be achieved by detecting the voltage value corresponding to the measured voltage signal 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 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 it is determined whether there is a problem of 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 in step S203 can be compared with the baseline 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, so as to determine whether there is displacement or warping of the wafer thinning film.

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

[0083] The step of creating an electrical parameter reference database may include the following steps: First, a reference wafer thinning sheet is placed on a wafer heating plate and a station calibration is performed, wherein the reference wafer thinning sheet is at least a wafer thinning sheet without warpage.

[0084] Next, the reference wafer thinning sheet is lifted to different detection positions by using multiple retractable pins in the wafer thinning sheet stress monitoring device and the values ​​of the electrical parameters corresponding to the different detection positions are detected. The reference wafer thinning sheet is lifted to different detection heights by multiple retractable pins. Every time a detection height is reached, the values ​​of the electrical parameters related to the resistive strain sensors corresponding to each retractable pin at the detection height are detected. Among them, the values ​​of the electrical parameters related to the resistive strain sensors corresponding to each retractable pin detected at different detection heights are used as reference values.

[0085] In certain embodiments, the resistive strain sensors in the multiple stress monitoring components are combined and connected in parallel to construct a constant voltage shunt strain monitoring circuit. Through the above-mentioned detection, the current value related to the resistive strain sensor corresponding to each retractable ejector pin at different detection heights can be detected.

[0086] In certain embodiments, the resistive strain sensors in the multiple stress monitoring components are combined and connected in series to construct a constant current voltage divider strain monitoring circuit. Through the above-mentioned detection, the voltage value related to the resistive strain sensor corresponding to each retractable ejector pin at different detection heights can be detected.

[0087] Finally, an electrical parameter benchmark database is created based on the different detection positions obtained and the values ​​of the electrical parameters corresponding thereto.

[0088] Therefore, in step S205, the measured data of the electrical parameters related to the resistive strain sensors in each stress monitoring component obtained in step S203 are compared with the baseline values ​​of the electrical parameters related to the resistive strain sensors in each stress monitoring component to obtain 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. Based on the change amount and change distribution characteristics of the electrical parameters related to each resistive strain sensor, it is determined whether the wafer thinning sheet has problems such as displacement or warping.

[0089] 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. For example, when the wafer thinning sheet corresponding to the supporting portion of the retractable ejector pin in a certain stress monitoring component is warped upward or the wafer thinning sheet is shifted and moved away, the pressure on the wafer thinning sheet applied to the supporting portion of the retractable ejector pin in the stress monitoring component will decrease, and the resistance value of the resistive strain sensor will increase. Under constant pressure, the measured current value associated with the resistive strain sensor will decrease, which is smaller than the reference value of the current parameter. For details, please refer to Figure 6 The retractable ejector pin on the far right.

[0090] 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 greater pressure from the wafer thinning sheet, it will contract and drive the resistive strain sensor at the bottom to compress. After compression, the length of the resistive strain sensor decreases and the cross-sectional area increases, resulting in a decrease in resistance value, 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. For example, when the wafer thinning sheet corresponding to the supporting portion of the retractable ejector pin in a certain stress monitoring component warps downward or the wafer thinning sheet shifts and approaches, the supporting portion of the retractable ejector pin in the stress monitoring component will be subjected to greater pressure from the wafer thinning sheet, and the resistance value of the resistive strain sensor will decrease. Under constant pressure conditions, the measured current value associated with the resistive strain sensor will increase, which is greater than the reference value of the current parameter. For details, please refer to Figure 7 The retractable ejector pin on the far right.

[0091] Similarly, 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, 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; for example, when the wafer thinning sheet corresponding to the supporting portion of the retractable ejector pin in a certain stress monitoring component is warped upward or the wafer thinning sheet is displaced and moved away, the pressure on the supporting portion of the retractable ejector pin in the stress monitoring component from the wafer thinning sheet will decrease, and the resistance value of the resistive strain sensor will increase. Under constant current conditions, the measured voltage value associated with the resistive strain sensor will increase, which is greater than the reference value of the voltage parameter. For details, please refer to Figure 8 The retractable ejector pin on the far right.

[0092] In the constant current voltage-dividing strain monitoring circuit, when the supporting part of the retractable ejector pin in a certain stress monitoring component is subjected to greater pressure from the wafer thinning sheet, it will contract and drive the resistive strain sensor at the bottom to compress. After compression, the length of the resistive strain sensor is reduced and the cross-sectional area is increased, resulting in a decrease in resistance value, and the measured voltage value associated with the resistive strain sensor is reduced, that is, the measured voltage value associated with 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 ejector pin in a certain stress monitoring component is warped downward or the wafer thinning sheet is shifted and moved closer, the supporting part of the retractable ejector pin in the stress monitoring component is subjected to greater pressure from the wafer thinning sheet, and the resistance value of the resistive strain sensor is reduced. Under constant current conditions, the measured voltage value associated with the resistive strain sensor will decrease, which is smaller than the reference value of the voltage parameter. For details, please refer to Fig. 9 The retractable ejector pin on the far right.

[0093] In this way, through the above-mentioned stress monitoring method of the wafer thinning sheet, the measured data of the electrical parameters related to the resistive strain sensor in each stress monitoring component is obtained through the strain monitoring circuit, and according to the change of the measured data compared with the reference value, it can be judged whether the wafer thinning sheet has a problem of displacement or warping. For example, when the measured data of the electrical parameters related to the resistive strain sensor in each stress monitoring component is changed compared with the reference value of the corresponding electrical parameter and the change exceeds the set threshold, it can be judged that the wafer thinning sheet has a problem of displacement or warping, and subsequently, corresponding adjustment measures can be taken according to the problem of displacement or warping of the wafer thinning sheet. For example, if the wafer thinning sheet is displaced, the wafer thinning sheet can be calibrated at the workstation so that the wafer thinning sheet is adjusted 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 gas filled, the power of the plasma generator, etc.

[0094] From the analysis of the above conditions, it can be seen that when the wafer warps or shifts, the current change obtained by comparing the actual current value of the resistive strain sensor in the constant voltage shunt strain monitoring circuit with the corresponding reference current value can be verified, or the voltage change obtained by comparing the actual voltage value of the resistive strain sensor in the constant current divider strain monitoring circuit with the corresponding reference voltage value can be verified.

[0095] However, it is not possible to determine whether the wafer thinning sheet has a warping problem or a shifting problem by the current change of a single resistive strain sensor in a constant voltage shunt strain monitoring circuit or the voltage change in a constant current voltage-divider strain monitoring circuit. Therefore, in the disclosed embodiment, the determination is made after the overall electrical parameter analysis of each stress monitoring component in the wafer thinning sheet stress monitoring device, 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 the wafer thinning sheet is determined to have a shifting or warping problem.

[0096] Taking the constant-voltage shunt 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 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 is a problem of displacement or warping of the wafer thinning sheet.

[0097] In certain embodiments, if the current change distribution characteristics of 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 the current value has changed but the current change amount does not exceed the current threshold, then it can be determined that the wafer thinning sheet has a warping problem or that the probability of the wafer thinning sheet having a warping problem is higher and the probability of a shifting problem is lower.

[0098] In some embodiments, if the distribution characteristics of the current changes in each resistive strain sensor show that the current values ​​of all the resistive strain sensors have changed and most or all of the current changes exceed the current threshold set according to the process requirements, it can be determined that the wafer thinning sheet has a shift problem or that the probability of the wafer thinning sheet having a shift problem is higher and the probability of a warping problem is lower.

[0099] Taking the constant current voltage divider strain monitoring circuit as an example, by comparing the measured voltage value of the resistive strain sensor in each stress monitoring component with the corresponding voltage reference value, the voltage change 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 there is a problem of displacement or warping of the wafer thinning sheet.

[0100] In certain embodiments, if the voltage change distribution characteristics of each resistive strain sensor show that the voltage value of a single or individual resistive strain sensor has changed and the voltage change exceeds the voltage threshold set according to the process requirements, while the voltage values ​​of other resistive strain sensors have not changed, or the voltage value has changed but the voltage change does not exceed the voltage threshold, then it can be determined that the wafer thinning sheet has a warping problem or that the probability of the wafer thinning sheet having a warping problem is higher and the probability of a shifting problem is lower.

[0101] In certain embodiments, if the voltage change distribution characteristics of each resistive strain sensor show that the voltage values ​​of all the resistive strain sensors have changed and most or all of the voltage changes exceed the voltage threshold set according to the process requirements, it can be determined that the wafer thinning sheet has a shift problem or that the probability of the wafer thinning sheet having a shift problem is higher and the probability of a warping problem is lower.

[0102] 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 detected stress monitoring component and the reference value of the electrical parameters are input into the electrical parameter analysis model, or the change amount 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 value of the electrical parameters are input into the electrical parameter analysis model, and the electrical parameter analysis model determines whether there is a problem of displacement or warping of the wafer thinning sheet according to the change amount and change distribution characteristics of the electrical parameters related to each resistive strain sensor. In some applications, the electrical parameter analysis model can be constructed based on a machine learning model and obtained through training. As an example, the machine learning model can be implemented as a neural network model. The neural network model can 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, and the output layer includes one or more output nodes (determined according to the number of output parameters), which are 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 has a corresponding weight, and each hidden node may have an offset value. The hidden node calculates the input of each branch line (such as weighted sum), and outputs it to the next level node (hidden node or output node) after adding the offset value, and finally forms an output at the output node.

[0103] As examples, machine learning models include, but are not limited to, neural networks, such as generative adversarial networks (GANs), regional convolutional neural networks (R-CNNs), region proposal networks (RPNs), recurrent neural networks (RNNs), stacked deep neural networks (S-DNNs), state-space dynamic neural networks (S-SDNNs), deconvolution networks, deep belief networks (DBNs), restricted Boltzmann machines (RBMs), fully convolutional networks, long short-term memory (LSTM) networks, etc. Alternatively or additionally, machine learning models may include other forms including ensembles such as random forests, such as, for example, linear and / or logistic regression, statistical clustering, Bayesian classification, decision trees, dimensionality reduction (such as, principal component analysis PCA), and expert systems and / or combinations thereof.

[0104] The following is a detailed description of the application of the above-mentioned wafer thinning stress monitoring method in actual process in conjunction with the accompanying drawings, as follows: See also Fig.10 , four monitoring points are provided on the wafer heating plate 11 , and the four monitoring points form a square at intervals of 90° and are all on the circumference of a formed monitoring circle. The monitoring points may be, for example, detection holes that penetrate the wafer heating plate 11 .

[0105] The retractable ejector pins in the stress monitoring assembly are correspondingly inserted into the detection holes on the wafer heating plate 11. After the retractable ejector pins are inserted into the detection holes, the supporting parts of the retractable ejector pins protrude from the upper side of the wafer heating plate 11. In this way, the multiple supporting parts of the four retractable ejector pins protruding from the wafer heating plate 11 can form a supporting surface for supporting the wafer thinning sheet 100. Fig.10 In the embodiment, the retractable ejector pins at the four monitoring points can be respectively identified as P1, P2, P3, and P4.

[0106] A resistive strain sensor (not shown in the figure) is connected to the bottom of each retractable ejector pin 21. The resistive strain sensors in the multiple stress monitoring components are connected in parallel to form a constant voltage shunt strain monitoring circuit, or the resistive strain sensors in the multiple stress monitoring components are connected in series to form a constant current shunt strain monitoring circuit.

[0107] Take the constant voltage shunt strain monitoring circuit as an example: Create an electrical parameter reference database: first place the reference wafer thinning sheet on the wafer heating plate and perform station calibration, then use multiple retractable pins in the wafer thinning sheet stress monitoring device to lift the reference wafer thinning sheet to different detection heights and detect the current values ​​corresponding to different detection heights; based on the different detection heights obtained and their corresponding current values, create a current reference database corresponding to the constant voltage shunt strain monitoring circuit, wherein the corresponding current values ​​detected at different detection heights are used as reference current values.

[0108] Fig.11 It is a schematic diagram showing the current-time variation corresponding to when multiple retractable ejectors lift the reference wafer thinning sheet to a certain detection height, such as Fig.11 As shown in FIG. 1 , the resistance value of the resistive strain sensor connected to each retractable ejector pin P1, P2, P3, and P4 is stable at a certain detection height, so its current values ​​I1, I2, I3, and I4 are also stable (such as Fig.11 As shown in the figure, the current value of the resistive strain sensor is stable at 0.3A), and these current values ​​can be used as the reference current value for judging the wafer thinning sheet at a certain detection height. Therefore, if the reference wafer thinning sheet is supported to different detection heights by using multiple retractable ejectors in the wafer thinning sheet stress monitoring device, the reference current value corresponding to the resistance value of the resistive strain sensor connected to the retractable ejector at different detection heights can be obtained. In this way, a current reference database is created based on the different detection positions obtained and the corresponding reference current values.

[0109] In some embodiments, if the wafer thinning process warps, for example, see Fig.11 , the portion of the wafer thinning sheet corresponding to the retractable ejector pin P1 is warped, and the pressure of the wafer thinning sheet on the supporting portion of the retractable ejector pin P1 decreases, then the resistance value of the resistive strain sensor R1 corresponding to the retractable ejector pin P1 increases, and the measured current value I1 related to the resistive strain sensor R1 decreases, for example, to 0.2 amps; if the other portions of the wafer thinning sheet are not warped, the measured current values ​​I2, I3, and I4 related to the resistive strain sensors R2, R3, and R4 corresponding to the other retractable ejector pins P2, P3, and P4 remain at 0.3 amps.

[0110] In some embodiments, if the wafer thinning occurs, e.g., see Fig.11 , the wafer thinning sheet shifts toward the retractable ejector pin P4, and the pressure of the wafer thinning sheet on the supporting portion of the retractable ejector pin P4 increases, then the resistance value of the resistive strain sensor R4 corresponding to the retractable ejector pin P4 decreases, and the measured current value I4 related to the resistive strain sensor R4 increases, for example, to 0.45A; other retractable ejectors will also change due to the displacement of the wafer thinning sheet. For example, the pressure of the wafer thinning sheet on the supporting portion of the retractable ejector pin P1 decreases, then the resistance value I4 corresponding to the retractable ejector pin P1 increases. The resistance value of the resistive strain sensor R1 increases, and the measured current value I1 related to the resistive strain sensor R1 becomes smaller, for example, to 0.25 A; the pressure of the supporting part of the retractable ejector pins P2 and P3 caused by the wafer thinning increases (or decreases), then the resistance values ​​of the resistive strain sensors R2 and R3 corresponding to the retractable ejector pins P2 and P3 decrease (or increase), and the measured current values ​​I2 and I3 related to the resistive strain sensors R2 and R3 increase (or decrease), for example, to 0.35 A (or 0.25 A).

[0111] Take the constant current voltage divider strain monitoring circuit as an example: Create an electrical parameter reference database: first place the reference wafer thinning sheet on the wafer heating plate and perform station calibration, then use multiple retractable pins in the wafer thinning sheet stress monitoring device to lift the reference wafer thinning sheet to different detection heights and detect the voltage values ​​corresponding to different detection heights; based on the different detection heights obtained and their corresponding voltage values, create a voltage reference database corresponding to the constant current voltage divider strain monitoring circuit, wherein the corresponding voltage values ​​detected at different detection heights are used as reference voltage values.

[0112] Fig.12 It is a schematic diagram showing the voltage-time variation when multiple retractable ejectors lift the reference wafer thinning sheet to a certain detection height, such as Fig.12As shown in FIG. 1 , the resistance value of the resistive strain sensor connected to each retractable ejector pin P1, P2, P3, and P4 is stable at a certain detection height, so its voltage values ​​V1, V2, V3, and V4 are also stable (such as Fig.12 As shown in the figure, the voltage value of the detected resistive strain sensor is stable at 3V), and these voltage values ​​can be used as reference voltage values ​​for judging the wafer thinning sheet at a certain detection height. Therefore, if a plurality of retractable ejectors in the wafer thinning sheet stress monitoring device are used to lift the reference wafer thinning sheet to different detection heights, the reference voltage values ​​corresponding to the resistance value of the resistive strain sensor connected to the retractable ejector at different detection heights can be obtained. In this way, a voltage reference database is created based on the different detection positions obtained and the corresponding reference voltage values.

[0113] In some embodiments, if the wafer thinning process warps, for example, see Fig.12 , the portion of the wafer thinning sheet corresponding to the retractable ejector pin P1 is warped, and the pressure of the wafer thinning sheet on the supporting portion of the retractable ejector pin P1 decreases, then the resistance value of the resistive strain sensor R1 corresponding to the retractable ejector pin P1 increases, and the measured voltage value V1 related to the resistive strain sensor R1 increases, for example, to 3.5 volts; if the other portions of the wafer thinning sheet are not warped, the measured voltage values ​​V2, V3, and V4 related to the resistive strain sensors R2, R3, and R4 corresponding to the other retractable ejector pins P2, P3, and P4 remain at 3 volts.

[0114] In some embodiments, if the wafer thinning occurs, e.g., see Fig.12 , the wafer thinning sheet shifts toward the retractable ejector pin P4, and the pressure of the wafer thinning sheet on the supporting portion of the retractable ejector pin P4 increases, then the resistance value of the resistive strain sensor R4 corresponding to the retractable ejector pin P4 decreases, and the measured voltage value V4 related to the resistive strain sensor R4 decreases, for example, to 2 volts; other retractable ejectors will also change due to the displacement of the wafer thinning sheet. For example, the pressure of the wafer thinning sheet on the supporting portion of the retractable ejector pin P1 decreases, then the voltage value V4 corresponding to the retractable ejector pin P1 increases. The resistance value of the resistive strain sensor R1 increases, and the measured voltage value V1 related to the resistive strain sensor R1 increases, for example, to 4 volts; the pressure of the supporting part of the retractable ejector pins P2 and P3 due to the wafer thinning increases (or decreases), and the resistance values ​​of the resistive strain sensors R2 and R3 corresponding to the retractable ejector pins P2 and P3 decrease (or increase), and the measured voltage values ​​V2 and V3 related to the resistive strain sensors R2 and R3 decrease (or increase), for example, to 2.5 volts (or 3.5 volts).

[0115] The stress monitoring method for wafer thinning sheets disclosed in the present invention may further include an overall analysis of measured data of electrical parameters related to resistive strain sensors in each stress monitoring component to evaluate whether a wafer thinning sheet with a shift or warping problem is more likely to have a shift problem or a warping problem.

[0116] In some embodiments, by comparing the measured data of electrical parameters related to the resistive strain sensors in the obtained multiple stress monitoring components with the reference values ​​of their respective corresponding electrical parameters, if it is found that only the measured data of the electrical parameters related to one or a few resistive strain sensors have changed and the amount of change exceeds the set threshold, but the measured data of the electrical parameters related to the other resistive strain sensors have not changed or the amount of change does not exceed the set threshold, 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, such as the heating problem of the heating plate, the flow rate of the filling gas, the power of the plasma generator, etc.

[0117] In some embodiments, by comparing the measured data of electrical parameters related to the resistive strain sensors in the obtained multiple stress monitoring components with the reference values ​​of the electrical parameters corresponding to them, if it is found that the measured data of the electrical parameters related to all or most of the resistive strain sensors have changed and the amount of change exceeds the set threshold, it can be evaluated that the wafer thinning sheet is more likely to have a displacement problem and it can be roughly determined which position (positions) of the wafer thinning sheet has shifted. Subsequently, the wafer thinning sheet can be calibrated so that the wafer thinning sheet is adjusted to the reference position.

[0118] The present disclosure provides a stress monitoring method for a wafer thinning sheet. By providing a wafer thinning sheet stress monitoring device, multiple stress monitoring components are arranged one by one at multiple monitoring points of a wafer heating plate. The resistive strain sensors in the multiple stress monitoring components are connected in combination to form 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 are obtained, and the problem of displacement or warping of the wafer thinning sheet is determined accordingly. 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, is accurate in detection, and takes corresponding adjustment measures when the wafer thinning sheet is detected to be displaced or warped, which is beneficial to the subsequent process of semiconductor wafers and improves the yield.

[0119] The disclosed embodiment further provides a wafer thinning stress monitoring and control device, which is applied to semiconductor process equipment. Taking the semiconductor process equipment as a wafer debonding device as an example, the wafer debonding device may include a debonding chamber, a wafer heating plate, at least one air intake device, and an exhaust device.

[0120] See also Fig.13 , which is a principle block diagram of a wafer thinning stress monitoring and control device provided by the present invention in one embodiment.

[0121] like Fig.13 As shown, the wafer thinning sheet stress monitoring control device 3 includes a processor 31 and a memory 33. The processor 31 and the memory 33 can communicate through a bus 32. The memory 33 can store a wafer thinning sheet stress monitoring program. The processor 31 executes each step of the wafer thinning sheet stress monitoring method by running the internal leakage detection program in the memory 33.

[0122] The bus 32 may be a Peripheral Component Interconnect (PCI) bus or an Extended Industry Standard Architecture (EISA) bus, etc. The bus may be divided into an address bus, a data bus, a control bus, etc. For ease of representation, although only one thick line is used in the figure, it does not mean that there is only one bus or one type of bus.

[0123] In some embodiments, the processor 31 may be implemented as a central processing unit (CPU), a microcontroller unit (MCU), a system on chip (SoC), or a field programmable gate array (FPGA). The memory 33 may include a volatile memory for temporary storage of data when running a program, such as a random access memory (RAM). The memory 33 may also include a non-volatile memory (NVM) for data storage, such as a read-only memory (ROM), a flash memory, a hard disk drive (HDD), or a solid-state disk (SSD).

[0124] In an embodiment of the present disclosure, a computer-readable storage medium may be provided, storing a computer program or instructions, which, when executed, implements the method flow or functions in any of the previous embodiments.

[0125] That is, the method steps in the above-described 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 downloaded via a network and to be stored in a local recording medium, so that the methods represented herein can be processed by such software stored on a recording medium using a general-purpose computer, a dedicated processor, or programmable or dedicated hardware (such as an ASIC or FPGA).

[0126] In the embodiments of the present disclosure, a computer program product may be provided, one or more computer programs or instructions, which, when executed, 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.

[0127] The computer program or instructions may be stored in a readable storage medium or transmitted from one readable storage medium to another readable storage medium, for example, the computer program or instructions may be transmitted from one website, computer, server or data center to another website, computer, server or data center by wired or wireless means. The readable storage medium may be any available medium that can be accessed or a data storage device such as a server, data center, etc. that integrates one or more available media. The available medium may be a magnetic medium, such as a floppy disk, a hard disk, or a magnetic tape; it may also be an optical medium, such as a digital video disk; it may also be a semiconductor medium, such as a solid state drive. The computer readable storage medium may be a volatile or non-volatile storage medium, or may include both volatile and non-volatile types of storage media.

[0128] The above embodiments are merely illustrative of the principles and effects of the present disclosure, and are not intended to limit the present disclosure. Anyone familiar with the technology may modify or change the above embodiments without violating 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 in the present disclosure shall 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 baseline values ​​of the electrical parameters, the change amount and change distribution characteristics of the electrical parameters related to each resistive strain sensor are obtained, thereby determining whether there is a problem of displacement or warping of the wafer thinning sheet.

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 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 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 measured data of electrical parameters related to the resistive strain sensors in each stress monitoring component, and the measured data of the electrical parameters related to the resistive strain sensors in each stress monitoring component are compared with the reference value 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 the wafer thinning sheet has a displacement or warping problem.

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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