Wafer thinning device and thinning method

Abstract

The invention provides wafer thinning equipment and a wafer thinning method, and belongs to the technical field of integrated circuit manufacturing. The thinning method comprises the steps of obtaining surface shape features of a wafer in the wafer grinding process of the wafer thinning equipment; determining a compensation angle of the main shaft based on the surface shape feature; inputting the compensation angle into a thermal expansion compensation angle model to obtain an output target temperature; and the temperature of the adjusting base plate is adjusted to reach the target temperature, so that the adjusting base plate generates corresponding deformation based on the temperature change to adjust the inclination angle of the main shaft. The wafer grinding efficiency and the grinding precision are improved.

Description

Technical Field

[0001] This application belongs to the field of integrated circuit manufacturing technology, and more specifically, relates to a wafer thinning device and a thinning method. Background Technology

[0002] Three-dimensional integrated circuits (3D ICs) are an important technological path for the semiconductor industry to continue Moore's Law and improve chip performance and integration. The core idea is to stack multiple chips or functional layers vertically and achieve interlayer electrical connections through interconnection technologies such as through-silicon vias (TSVs), thereby achieving higher functional density within a limited space.

[0003] Wafer thinning is a key supporting process in 3D IC manufacturing, its main purpose being to reduce the wafer's thickness from its original level to an ultra-thin state suitable for vertical integration. Ultra-thin wafers are the physical basis for achieving three-dimensional stacking and are crucial for optimizing electrical performance and thermal management. As the number of stacked layers in 3D ICs increases, the requirements for the thinning thickness of individual wafers become increasingly stringent. Simultaneously, 3D ICs place extremely high demands on the surface quality of the thinned wafer, including excellent Total Thickness Variation (TTV) and extremely low Roughness Average (Ra), to ensure the accuracy, consistency, and stability of subsequent bonding processes, thereby guaranteeing the yield of the finished integrated circuit chips.

[0004] To achieve these goals, wafer thinning equipment typically utilizes the physical grinding action of grinding wheels to process ultra-thin wafers. Such equipment must have its grinding structure and process precisely designed and controlled to meet the requirements for ultra-thin wafer processing (such as thickness ≤10μm, TTV ≤1.5μm, and Ra ≤5nm) while also considering manufacturing costs and production efficiency.

[0005] From a grinding structure perspective, the spindle orientation of a wafer thinning machine directly affects the contact angle between the grinding wheel and the wafer. Therefore, adjusting the spindle tilt angle can be used to adjust the wafer's surface features, thereby improving the wafer's grinding accuracy. Currently, the industry typically only manually adjusts the spindle tilt angle mechanically before starting the wafer thinning machine. On the one hand, this is limited by the mechanical adjustment structure, resulting in low adjustment accuracy. Furthermore, human error due to varying operator experience makes it impossible to guarantee adjustment precision, thus affecting wafer grinding accuracy. On the other hand, it suffers from adjustment delay, failing to respond promptly to wafer surface deviations and adjust the spindle tilt angle in a timely manner to adjust the wafer surface by changing the entry angle. This leads to the gradual accumulation of wafer surface deviations without timely correction, ultimately making it difficult to meet wafer grinding accuracy requirements and resulting in a decrease in wafer yield. Summary of the Invention

[0006] Based on the above problems, this application provides a wafer thinning apparatus and a thinning method, which aims to at least solve or alleviate one of the technical problems existing in the prior art.

[0007] A first aspect of this application provides a wafer thinning apparatus, including: a grinding device, an adsorption platform, and a temperature control unit; The adsorption platform is used to support the wafer and drive its rotation; The grinding device is raised and lowered above the adsorption platform. The grinding device includes a spindle for driving the grinding wheel to rotate. The grinding device also includes: a spindle seat, a feed mechanism, and an adjusting plate; the spindle is rotatably and coaxially disposed within the spindle seat; the spindle seat is connected to the feed mechanism; the adjusting plate is at least partially inserted between the feed mechanism and the spindle seat; the adjusting plate is provided with a temperature regulating component; The temperature control unit, electrically connected to the temperature adjustment component, is used to determine the spindle compensation angle based on the surface features of the wafer. The compensation angle is input into the thermal expansion compensation angle model to obtain the output target temperature. By adjusting the temperature of the temperature adjustment component, the temperature of the adjustment pad reaches the target temperature, causing the adjustment pad to deform accordingly based on the temperature change, thereby adjusting the spindle tilt angle.

[0008] In one embodiment, the spindle seat includes a tubular main body and outwardly extending wing plates on its left and right sides; the feed mechanism includes a slide rail arranged in a vertical direction and a slider that moves vertically along the slide rail. The adjusting pad is inserted at least partially between the slider and the wing plate.

[0009] In one embodiment, the adjusting pad includes an upper pad and a lower pad, which are inserted downward and upward, respectively, between the slider and the wing plate.

[0010] In one embodiment, the temperature regulating component is disposed on at least one of the upper pad and the lower pad.

[0011] In one embodiment, the temperature regulating component includes: A temperature sensor and at least one temperature control actuator are included. Both the temperature sensor and the temperature control actuator are electrically connected to the temperature control unit. The temperature sensor is used to monitor the temperature of the regulating pad.

[0012] In one embodiment, the thermal expansion compensation angle model is constructed as follows: Based on the horizontal displacement of the lower support point after the lower pad is deformed by heat, the spindle tilt angle of the lower pad after deformation is calculated. Based on the equality that the difference between the spindle tilt angle of the lower pad after deformation and the initial spindle tilt angle is equal to the compensation angle, the target temperature at which the lower pad deforms is determined; or Based on the horizontal displacements of the upper and lower pads at the upper and lower supports respectively after thermal deformation, the spindle tilt angles of the upper and lower pads after thermal deformation are calculated. Based on the equality that the difference between the spindle tilt angles of the upper and lower pads after thermal deformation and the initial spindle tilt angle is equal to the compensation angle, the target temperature at which the lower or upper pad undergoes deformation is determined.

[0013] A second aspect of this application provides a thinning method, comprising: To obtain the surface features of the wafer during the wafer grinding process using a wafer thinning equipment; The compensation angle of the spindle is determined based on the surface features. The spindle is connected to the grinding wheel for grinding the wafer to drive the grinding wheel to rotate, and the spindle is located in the spindle seat. Input the compensation angle into the thermal expansion compensation angle model to obtain the output target temperature; Adjust the temperature of the adjusting shim between the spindle seat and the feed mechanism to the target temperature, so that the adjusting shim deforms accordingly based on the temperature change, thereby adjusting the spindle tilt angle.

[0014] In one embodiment, the adjusting pad includes an upper pad and a lower pad that are inserted downwards and upwards between the spindle seat and the feed mechanism, respectively. The thermal expansion compensation angle model is constructed as follows: based on the horizontal displacement of the lower pad at the lower support point after thermal deformation, the spindle tilt angle after deformation of the lower pad is calculated; based on the equality relationship that the difference between the spindle tilt angle after deformation of the lower pad and the initial spindle tilt angle is equal to the compensation angle, the target temperature at which the lower pad deforms is solved.

[0015] In one embodiment, the adjusting pad includes an upper pad and a lower pad inserted downwards and upwards respectively between the spindle seat and the feed mechanism. The thermal expansion compensation angle model is constructed as follows: based on the horizontal displacement of the upper and lower pads at the upper and lower support points after thermal deformation, the spindle tilt angle after thermal deformation of the upper and lower pads is calculated. Based on the equality relationship that the difference between the spindle tilt angle after thermal deformation of the upper and lower pads and the initial spindle tilt angle is equal to the compensation angle, the target temperature at which the lower or upper pad deforms is solved.

[0016] In one embodiment, the thermal expansion compensation angle model is constructed as follows: The horizontal displacement of the upper pad at the upper support point after thermal deformation is calculated based on the thermal expansion coefficient of the upper pad, temperature change, and thickness of the upper pad at the upper support point. The horizontal displacement of the lower pad at the lower support point after thermal deformation is calculated based on the thermal expansion coefficient of the lower pad, temperature change, and thickness of the lower pad at the lower support point. Based on the difference between the thickness of the lower pad at the lower support point after thermal deformation and the thickness of the upper pad at the upper support point after thermal deformation, the initial distance between the upper support point and the upper surface of the lower pad, and the length of the lower pad along the main axis, the main axis tilt angle of the lower or upper pad after thermal deformation is calculated.

[0017] In one embodiment, the thinning method includes: When the compensation angle is greater than 0°, the target temperature at which the lower pad deforms is solved by the thermal expansion compensation angle model, and the temperature of the lower pad is adjusted to the target temperature. When the compensation angle is less than 0°, the target temperature at which the upper pad deforms is solved by the thermal expansion compensation angle model, and the temperature of the upper pad is adjusted to the target temperature.

[0018] In one embodiment, determining the compensation angle of the principal axis based on surface features includes: The surface features are input into the arc surface model to obtain the current principal axis tilt angle. The arc surface model is based on the grinding line structure formed when the grinding wheel contacts the wafer. The arc surface model is used to characterize the correspondence between the surface features and the principal axis tilt angle. The difference between the current spindle tilt angle and the target tilt angle is determined as the compensation angle.

[0019] In one embodiment, the output current spindle tilt angle includes: a first-dimensional tilt angle and a second-dimensional tilt angle. The contact portion between the grinding wheel and the wafer forms an arc-shaped grinding line. One end of the grinding line is located at the center of the wafer, and the other end is located at the edge of the wafer. The first dimension is the wafer radius direction where both ends of the grinding line are located, and the second dimension is a horizontally extending direction perpendicular to the first dimension. The difference between the current spindle tilt angle and the target tilt angle is determined as the compensation angle, including: The difference between the first-dimensional tilt angle and the first-dimensional target tilt angle is determined as the compensation angle.

[0020] The beneficial effects of the wafer thinning equipment and thinning method provided in this application embodiment are as follows: This application can determine the spindle compensation angle based on the surface features of the wafer, and obtain the output target temperature by inputting the compensation angle into the thermal expansion compensation angle model. Furthermore, the temperature of the adjustment pad is adjusted to reach the target temperature, so that the adjustment pad deforms accordingly based on the temperature change, thereby adjusting the spindle tilt angle.

[0021] This application achieves closed-loop control of the surface features of wafer grinding, eliminating the delay and uncertainty of manual mechanical adjustment, significantly reducing the dependence of adjustment results on operator skills, reducing errors caused by human operation, effectively improving the overall efficiency of wafer grinding, and improving wafer grinding accuracy.

[0022] This application utilizes the thermal expansion and contraction properties of the adjusting pad. By precisely controlling the temperature change of the adjusting pad, the adjusting pad undergoes corresponding deformation, thereby achieving ultra-fine adjustment of the spindle tilt angle. This avoids the inherent step-like changes of mechanical adjustment, enabling more precise and stable stepless adjustment of the spindle tilt angle, more accurately controlling the wafer grinding surface shape, and improving wafer grinding accuracy. This provides technical support for ultra-high density semiconductor stacking processes. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1 This is a schematic diagram of the structure of a wafer thinning apparatus according to an embodiment of this application; Figure 2 A schematic diagram of the surface features of a wafer provided in an embodiment of this application; Figure 3 A schematic diagram of the surface features of a wafer provided in another embodiment of this application; Figure 4 for Figure 1 Schematic diagram of the intermediate grinding device; Figure 5 for Figure 4 Left view of one embodiment of the intermediate grinding apparatus; Figure 6 for Figure 4 Left view of another embodiment of the intermediate grinding device; Figure 7 This is a flowchart of a thinning method provided in an embodiment of this application; Figure 8 This is a flowchart illustrating a method for constructing a thermal expansion compensation angle model according to an embodiment of this application. Figure 9 A flowchart of a method for constructing a thermal expansion compensation angle model is provided for another embodiment of this application; Figure 10 This is a schematic diagram of a grinding wheel used for wafer grinding according to an embodiment of this application; Figure 11 This is a structural block diagram of a thinning device provided in an embodiment of this application; Figure 12 This is a structural block diagram of an electronic device according to an embodiment of this application.

[0025] Figure label: 10. Grinding device; 11. Grinding wheel; 12. Spindle; 13. Spindle seat; 131. Main body; 132. Wing plate; 14. Feed mechanism; 141. Slide rail; 142. Slider; 151. Upper pad; 1511. Upper fulcrum; 152. Lower pad; 1521. Horizontal part; 1522. Lower fulcrum; 16. Depth adjustment part; 20. Adsorption platform; 30. Worktable; 40. Base; 50. Wafer; 110. Feature acquisition unit; 111. Compensation angle determination unit; 112. Target temperature determination unit; 113. Tilt angle adjustment unit; 600. Electronic equipment; 601. Processor; 602. Input device; 603. Output device; 604. Memory; 605. Communication bus. Detailed Implementation

[0026] To enable those skilled in the art to better understand the technical solutions in the embodiments of this application, the technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments in the specific implementation of this application should fall within the protection scope of the embodiments of this application.

[0027] To keep the drawings concise, each drawing only schematically shows the parts relevant to the disclosure; these do not represent the actual structure of the product. Furthermore, for ease of understanding, in some drawings, only one of components with the same structure or function is schematically shown, or only one is labeled. In this document, "one" not only means "only one," but can also mean "more than one," and "several" includes "two" and "more than two."

[0028] In this document, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0029] In this application, unless otherwise expressly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0030] In the description of this embodiment, terms such as "upper," "lower," "left," and "right" are based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of description and simplification of operation, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0031] Furthermore, in the description of this application, the terms "first," "second," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0032] It should be understood that, unless the context clearly states otherwise, the terms "comprising," "including," or "having" as used herein refer to the presence of an element, but do not exclude the presence or addition of one or more other elements. Furthermore, "comprising" and / or "including" as used herein specify the presence of shapes, numbers, steps, operations, members, elements, and / or combinations thereof, and do not exclude the presence or addition of one or more other shapes, numbers, operations, elements, and / or combinations thereof. Some embodiments of this application are described in detail below with reference to the accompanying drawings. Where there is no conflict between the embodiments, the following embodiments and features can be combined with each other. The steps in the following method embodiments are for illustrative purposes only and are not intended to limit this application.

[0033] Figure 1A schematic diagram of a wafer thinning apparatus according to one embodiment of this application is shown, including a grinding device 10 and an adsorption platform 20. A worktable 30 is used to support and drive the adsorption platform 20 to move, so that the grinding device 10 can act on wafers 50 on different adsorption platforms 20. At the same time, the adsorption platform 20 can support the wafers 50 by adsorption and drive the wafers 50 to rotate. Although not shown, existing wafer thinning apparatuses usually avoid heat-induced deformation from affecting the final wafer 50 processing results by supplying cooling water to the adsorption platform 20 and / or the wafers 50. At the same time, the prior art also optimizes the material of the adsorption platform 20, for example, by using ceramic materials with low thermal expansion coefficients and / or Invar alloys to reduce the impact of thermal deformation.

[0034] However, since the grinding device 10 is vertically mounted above the adsorption platform 20, heat that cannot be dissipated in time by cooling water is conducted upwards to the grinding device 10, thus affecting its positional factors. The grinding device 10 includes a spindle 12 and a grinding wheel 11, with the spindle 12 coaxially connected to the grinding wheel 11 and driving the grinding wheel 11 to rotate. On the other hand, in high-heat operations such as grinding hard materials like SiC, external cooling of the grinding device 10 may lead to undesirable consequences such as insufficient cooling water acting on the grinding device 10 or a serious over-consumption of total water.

[0035] During the rotation of the grinding wheel 11, the wafer 50 can be ground. A semi-contact grinding method can be used, that is, the grinding wheel 11 only contacts the area from the center to the edge of the wafer 50 to perform grinding. After grinding, the wafer 50 has surface features, including concavity and fullness. Figure 2 and Figure 3 Examples of convexity and fullness are given for two cases: convex and concave surfaces, respectively. δ 1 represents the degree of concavity / convexity, expressed as... δ 2 indicates fullness.

[0036] In this application, the grinding wheel 11 can adjust the surface features of the wafer 50 while grinding the wafer 50. Specifically, this application adjusts the surface features of the wafer 50 by changing the angle between the grinding wheel 11 and the upper surface of the wafer 50 by adjusting the spindle tilt angle.

[0037] Reference Figure 4 and Figure 5 , Figure 4 for Figure 1 Schematic diagram of the intermediate grinding device 10 Figure 5 for Figure 4Left view of the grinding device 10. The grinding device 10 also includes a spindle seat 13, a feed mechanism 14, and an adjusting pad. The spindle 12 is rotatably mounted in the spindle seat 13, and the spindle seat 13 is connected to the feed mechanism 14. The feed mechanism 14 can drive the spindle seat 13, the spindle 12, and the grinding wheel 11 to move up and down as a whole.

[0038] like Figure 4 and Figure 5 As shown, the adjusting pad is at least partially inserted between the feed mechanism 14 and the spindle seat 13. Specifically, the adjusting pad may include an upper pad 151 and a lower pad 152. The adjusting pad is provided with a temperature regulating component (not shown). The wafer thinning equipment also includes a temperature control unit. The temperature control unit is connected to the temperature regulating component to regulate the temperature of the temperature regulating component so that the temperature of the adjusting pad reaches the target temperature. The adjusting pad can produce corresponding deformation based on temperature changes in order to achieve ultra-fine adjustment of the spindle tilt angle.

[0039] In the traditional packaging field, the TTV requirement is generally between 1.5μm and 10μm, mainly considering the package size and heat dissipation performance. 3D IC stacking generally requires less than 1.5μm, but future stacking of more than 20 layers requires TTV to be less than 0.5μm or even 0.2μm. Therefore, the traditional method of adjusting the spindle tilt angle once before grinding is difficult to meet the extreme requirements of the new process for TTV. The new process requires real-time micro-adjustment of the spindle tilt angle during grinding.

[0040] When selecting the material for the adjusting pad, the effect of metal thermal creep need not be considered. This is because adjusting pads are usually made of high-strength materials such as carbon steel, and the creep initiation temperature is approximately (0.3~0.4) × T. m (K), approximately 229℃~396℃, far exceeding the operating temperature of the grinding wheel 11, and consequently far exceeding the operating temperature of the spindle 12 and spindle seat 13 cooled by cooling water (20℃ to 60℃), and from T / T m Considering the creep condition of >0.3~0.4, the influence of the thermal field on the strength of the adjusting pad can also be ruled out. Since the coefficient of thermal expansion of the adjusting pad is stable, the adjusting pad can be deformed accordingly by precisely controlling the temperature change of the adjusting pad. The amount of deformation can be precisely controlled. Therefore, bidirectional micro-adjustment of the spindle tilt angle can be achieved by independently controlling the contraction and / or expansion of the upper pad 151 and the lower pad 152.

[0041] It should be noted that the coefficient of thermal expansion of the material of the adjusting pad that contacts the main body 131 should be greater than or equal to that of the main body 131, and it should have high antimagnetic properties (e.g., containing copper, silver, or graphite) and high compressive strength; in particular, considering the small thickness of the adjusting pad to reduce the overall volume of the grinding device 10 and control the accumulation of contaminants in the gaps, the adjusting pad should be selected with an overall coefficient of thermal expansion greater than 16 × 10⁻⁶. -6 Materials with a compressive strength greater than 500 MPa at / ℃ are preferred, and composite materials of metals and non-metals are preferred; furthermore, in order to achieve better thermal expansion effect, composite materials containing ABS plastic are preferred, including high modulus carbon fiber / epoxy resin and high temperature thermoplastic carbon fiber / PEEK.

[0042] In one embodiment, the temperature control unit is used to determine the compensation angle of the spindle 12 based on the surface features of the wafer 50, input the compensation angle into the thermal expansion compensation angle model, obtain the output target temperature, and adjust the temperature of the adjustment pad to reach the target temperature by adjusting the temperature of the temperature adjustment component (not shown), so that the adjustment pad will deform accordingly based on the temperature change, thereby adjusting the spindle tilt angle.

[0043] Although there are many components with temperature regulation functions in general applications, in this embodiment, considering factors such as the gap not being too wide to avoid introducing contaminants, the thickness of the adjusting pad cannot be increased significantly compared to the prior art. The adjustment of the spindle tilt angle can be accomplished by the cooperation of the upper pad 151 and the lower pad 152. In this embodiment, the temperature regulating components acting on the upper pad 151 and the lower pad 152 can work together to achieve the effects of heating and cooling (for example, the upper pad 151 expands when heated, and the lower pad 152 contracts when cooled).

[0044] The aforementioned temperature-regulating components, which have both heating and cooling functions, include devices such as Peltier tubes and eddy current tubes. The upper pad 151 and lower pad 152 can be configured to share a single temperature-regulating component, allowing heating and cooling energy to be transferred separately, thus saving space and volume and avoiding the introduction of contaminants. In this embodiment, an accurate target temperature is obtained through a thermal expansion compensation angle model. The temperature of the regulating pad is then adjusted to the target temperature using the temperature-regulating component, thereby controlling the deformation of the regulating pad to regulate the spindle tilt angle. This allows the spindle tilt angle to be controlled with an accuracy of 0.0001°. For example, with a temperature control accuracy of 2°C, the spindle tilt angle is controlled with an accuracy of 0.0001°, far exceeding the 0.01° typically achievable by traditional mechanical adjustment methods (such as screws and wedges). By adjusting the spindle tilt angle through the control of the temperature of the regulating pad, real-time monitoring and timely adjustment are possible. The continuous and smooth adjustment characteristics avoid the inherent abrupt changes of mechanical adjustment, thus enabling more precise and stable stepless micro-adjustment of the spindle tilt angle and more accurate control of the wafer grinding surface shape. Furthermore, the automated control of the temperature control component significantly reduces human uncertainty, greatly reduces the dependence of the adjustment results on operator skill, reduces adjustment operation errors, and further improves wafer grinding accuracy.

[0045] In one embodiment, such as Figure 4 As shown, the feed mechanism 14 includes two vertically arranged slide rails 141 and two vertically movably arranged sliders 142 on the slide rails 141. The slide rails 141 are fixed to the base 40 of the wafer thinning equipment. The spindle seat 13 includes a tubular main body 131 and outwardly extending wing plates 132 on its left and right sides. The spindle 12 is rotatably coaxially arranged in the main body 131. The wing plates 132 are parallel to the outer sides of the sliders 142, and the two wing plates 132 are respectively connected to the two sliders 142. Therefore, the spindle seat 13 and the spindle 12 as a whole can move vertically along the slide rails 141, thereby driving the grinding wheel 11 to rise and fall. In this embodiment, the adjustment of the spindle tilt angle refers to the adjustment of the spindle 12 along the slide rails 141. Figure 4 The middle arc b-b' is used for pitch adjustment, while the arc a-a' indicates that the main shaft 12 can be swung left and right along the arc. This application does not impose specific restrictions on the left and right sway adjustment.

[0046] like Figure 4 and Figure 5 As shown, an adjusting shim is disposed between the wing plate 132 and the slider 142. The depth at which the adjusting shim is inserted between the wing plate 132 and the slider 142 changes the distance between them, thereby changing the spindle tilt angle. In a specific embodiment, such as... Figure 5As shown, there are two sets of adjusting shims: an upper shim 151 and a lower shim 152. One or both of the upper shim 151 and the lower shim 152 can be wedge-shaped plates, allowing for mechanical adjustment of the spindle 12's pitch by adjusting the insertion depth of the wedge-shaped plates. The upper shim 151 and the lower shim 152 are inserted downwards and upwards, respectively, between the feed mechanism 14 and the spindle seat 13.

[0047] In one embodiment, such as Figure 4 As shown, the lower pad 152 is a wedge-shaped plate, and its lower end has a horizontal portion 1521 extending below the slider 142. The horizontal portion 1521 is provided with a rotatable depth adjustment portion 16, which is fixed in a vertically relative position to the horizontal portion 1521. The slider 142 has a depth-adjusting threaded hole that mates with the depth adjustment portion 16. Rotation of the depth adjustment portion 16 changes its depth within the depth-adjusting threaded hole, simultaneously moving the lower pad 152 and changing the depth at which it is inserted between the wing plate 132 and the slider 142. The depth adjustment portion 16 can rotate under the drive of components such as an adjusting motor (not shown). For example, the adjusting motor can be controlled to rotate according to a compensation angle, thereby achieving automatic adjustment of the spindle tilt angle. In this embodiment, the thickness variation rate of the lower pad 152 along the vertical direction can be set according to process requirements, thereby controlling the adjustment accuracy of the spindle tilt angle.

[0048] In another embodiment of this application (not limiting), a temperature regulating component is provided in at least one of the upper pad 151 and the lower pad 152. In one embodiment, the upper pad 151 is made of a material with a very low coefficient of thermal expansion, so the thermal deformation of the upper pad 151 can be ignored. Only the lower pad 152 is provided with a temperature regulating component, which can control the temperature of the lower pad 152. The lower pad 152 has the property of thermal expansion and contraction. After thermal expansion, the lower pad 152 will change the distance between the lower position of the wing plate 132 and the slider 142, that is, the lower pad 152 will deform in the horizontal direction, thereby realizing the fine adjustment of the spindle tilt angle. The deformation caused by the temperature change of the lower pad 152 is usually much smaller than the adjustment amount of mechanical adjustment. This embodiment utilizes the property of thermal expansion and contraction of the lower pad 152 to adjust the spindle tilt angle by adjusting the temperature of the lower pad 152, with high adjustment accuracy, reaching 0.0001°.

[0049] Non-limiting, in another embodiment, temperature regulating components are provided on both the upper pad 151 and the lower pad 152. By coordinating the temperature changes of the upper pad 151 and the lower pad 152, the spindle tilt angle can be reduced or increased, thereby minimizing the adjustment amount of each adjusting pad or maximizing the adjustment range. See also Figure 5As shown, when the thickness of the upper pad 151 changes, the thickness of the upper pad 151 at the upper support point 1511 also changes, and the direction of the thickness change is as follows. Figure 5 As indicated by the horizontal arrow, the spindle mount 13 rotates by an angle n in the first direction, thereby increasing the tilt angle of the spindle 12. (See also...) Figure 6 As shown, when the thickness of the lower pad 152 changes, the thickness of the lower pad 152 at the lower support point 1522 also changes, and the direction of the thickness change is as follows. Figure 6 As indicated by the horizontal arrow, the spindle seat 13 will rotate by an angle m in the first direction, thereby increasing the backward tilt angle of the spindle 12. It should be noted that the upper support point 1511 is the position where the upper end of the upper pad 151 contacts the wing plate 132. When the upper pad 151 is a wedge-shaped plate, the upper support point (actually a line / surface contact, but a point in the side view, the same below) 1511 is always at the position where the thickness of the upper pad 151 is greatest. The lower support point 1522 is the position where the lower end of the lower pad 152 contacts the wing plate 132. When the lower pad 152 is a wedge-shaped plate, the lower support point 1522 is always at the position where the thickness of the lower pad 152 is greatest. During temperature adjustment, the vertical positions of the upper support point 1511 and the lower support point 1522 will not change, and the vertical distance between the upper support point 1511 and the lower support point 1522 will remain unchanged.

[0050] It should be noted that this application can combine the tilt angle adjustment method using the depth adjustment unit 16 and the tilt angle adjustment method using the temperature control component. The depth adjustment unit 16 adjusts the depth of the adjustment shim inserted between the wing plate 132 and the slider 142 for coarse tilt angle adjustment, while the temperature control component adjusts the temperature of the adjustment shim to finely adjust the spindle tilt angle by adjusting the tilt angle through the deformation of the adjustment shim. The combination of coarse and fine adjustment can balance adjustment efficiency and accuracy, reducing adjustment deviations and cumulative errors.

[0051] In one embodiment, the temperature regulating component includes a temperature sensor and at least one temperature control actuator. Both the temperature sensor and the temperature control actuator are electrically connected to the regulating unit. The temperature sensor monitors the temperature of the regulating pad. Temperature sensors on both the upper pad 151 and the lower pad 152 are disposed on their surfaces. Further, for regulating pads made of metal and non-metal composite materials, the temperature sensors are preferably disposed on the surface or inside the pad on the side furthest from the temperature control actuator. After the temperature regulating unit controls the temperature regulating component to adjust the temperature of the regulating pad, the temperature sensor monitors the temperature of the regulating pad, forming a closed-loop temperature control and improving the accuracy of temperature control.

[0052] Considering that the strategy of coordinating the adjustment of the two adjustment pads is relatively complex, the following example of adjusting the lower pad 152 alone will be used to illustrate the adjustment method.

[0053] Reference Figure 7 , Figure 7 This is a flowchart of a wafer thinning method according to an embodiment of the present application. The method uses the wafer thinning equipment of the present application to grind the wafer and includes the following steps: S1: Obtain the surface features of the wafer during the wafer thinning process.

[0054] In one embodiment, the wafer thinning device may further include a monitoring component, which can acquire the surface features of the wafer at a preset frequency, that is, cyclically execute step S1 at certain time intervals.

[0055] In another embodiment, the surface features of the wafer during the grinding process can also be acquired by an external monitoring device. As mentioned above, the surface features of the wafer should also be acquired at a preset frequency. Those skilled in the art can set the preset frequency based on experience.

[0056] In one embodiment, the surface features of the wafer can be monitored by contact or non-contact measurement methods. Taking non-contact measurement as an example, it can be performed using an NCG (Non-contact Thickness Gauge). The NCG can be any of the following: a white light interferometer, a laser displacement sensor, or a spectral confocal displacement sensor, etc. This embodiment does not impose specific limitations on this.

[0057] In one embodiment, the monitoring process can select multiple feature radii (e.g., any integer from 5 to 10), such as five radii located at distances of 0.03R, 0.23R, 0.50R, 0.67R, and 0.90R from the center, where R represents the wafer radius. For each radius, multiple points (e.g., any integer from 20 to 30) are selected for thickness measurement. Data with significant deviations are discarded, and the average of the remaining thicknesses is taken as the thickness for that radius. Based on this thickness, the unevenness can be determined. δ 1 and fullness δ 2. For example, non-limitingly, the difference between the thickness at the minimum radius and the thickness at the maximum radius can be used as the unevenness. δ 1. The height difference between the maximum thickness and the line connecting the center and the edge is used as the fullness. δ 2.

[0058] S2: The compensation angle of the spindle 12 is determined based on the surface features. The spindle 12 is connected to the grinding wheel 11 for grinding the wafer to drive the grinding wheel 11 to rotate. The spindle 12 is located in the spindle seat 13.

[0059] The compensation angle of spindle 12 refers to the tilt angle of spindle 12 to be adjusted.

[0060] In one embodiment, the method for determining the compensation angle of the principal axis 12 based on surface features includes: The surface features obtained in step S1 can be input into a pre-constructed arc surface model to obtain the current spindle tilt angle; then the difference between the current spindle tilt angle and the target tilt angle is determined as the compensation angle of the spindle 12. The arc surface model is based on the grinding line structure formed when the grinding wheel 11 contacts the wafer, and is used to characterize the correspondence between the surface features and the spindle tilt angle.

[0061] S3: Input the compensation angle into the thermal expansion compensation angle model to obtain the output target temperature.

[0062] In one embodiment, the compensation angle calculated in step S2 can be input into a pre-built thermal expansion compensation angle model to determine the target temperature, which is the temperature that needs to be reached after the temperature adjustment pad is adjusted.

[0063] In one embodiment, if the adjusting pad includes an upper pad 151 and a lower pad 152, and the upper pad 151 is made of a material that is not easily deformed by heat, that is, the coefficient of thermal expansion of the upper pad 151 is small (the coefficient of thermal expansion of the upper pad 151 is less than or equal to a preset threshold for the coefficient of thermal expansion), then the deformation of the upper pad 151 can be ignored, and the spindle tilt angle can be adjusted only by adjusting the temperature change of the lower pad 152. In this case, the thermal expansion compensation angle model is constructed as follows: based on the horizontal displacement of the lower pad 152 at the lower support point 1522 after thermal deformation, the spindle tilt angle of the lower pad 152 after thermal deformation is calculated, and then based on the equality relationship that the difference between the spindle tilt angle of the lower pad 152 after thermal deformation and the initial spindle tilt angle is equal to the compensation angle, the target temperature at which the lower pad 152 deforms is solved.

[0064] In one embodiment, the horizontal displacement of the lower pad 152 at the lower support point 1522 after thermal deformation can be calculated based on the coefficient of thermal expansion of the lower pad 152, temperature change, and the thickness of the lower pad 152 at the lower support point 1522 (before thermal deformation). Furthermore, the spindle tilt angle of the lower pad 152 after thermal deformation can be solved based on the thickness of the lower pad 152 at the lower support point 1522 after thermal deformation, the thickness of the upper pad 151 at the upper support point 1511, the initial distance between the upper support point 1511 and the upper surface of the lower pad 152, and the length of the lower pad 152 along the spindle 12 direction.

[0065] Corresponding to the embodiment above that ignores the deformation of the upper pad 151, one embodiment of this application provides a method for constructing a thermal expansion compensation angle model, referring to... Figure 8 The flowchart for constructing the thermal expansion compensation angle model includes the following steps: S21. Determine the initial principal spindle tilt angle; The initial spindle tilt angle is the tilt angle between the spindle 12 and the axis of the adsorption platform 20 in the initial state, which is also the tilt angle between the spindle 12 and the axis of the wafer 50. The initial state is the state in which the adjusting pad has not been deformed, which can be understood as the state at the ambient temperature of the wafer thinning equipment or at room temperature.

[0066] In this embodiment, the initial spindle tilt angle It can be obtained based on the following relation: ; in, This indicates the thickness of the lower pad 152 at the lower support point 1522 (the horizontal thickness of the lower pad 152 before thermal deformation). This indicates the thickness of the upper pad 151 at the upper support point 1511 (the horizontal thickness of the upper pad 151 before thermal deformation). This indicates the initial distance between the upper fulcrum 1511 and the upper surface of the lower pad 152; This indicates the length of the lower pad 152 along the main shaft 12.

[0067] This embodiment is illustrated by taking the case where the lower pad 152 is just fully inserted between the feed mechanism 14 and the spindle seat 13 (that is, the lower surface of the lower pad 152 and the lower support point are on the same plane). If the lower pad 152 is partially inserted between the feed mechanism 14 and the spindle seat 13, then the corresponding... This indicates the length of the portion of the lower pad 152 inserted between the feed mechanism 14 and the spindle seat 13 along the direction of the spindle 12. If the lower pad 152 is a wedge-shaped plate, ensure that the entire wedge-shaped portion is inserted. The lowest end of the portion of the lower pad 152 inserted between the feed mechanism 14 and the spindle seat 13 is the non-wedge-shaped portion.

[0068] S22. Calculate the horizontal displacement of the lower support point 1522 after the lower pad 152 is deformed by heat. The lower pad 152 deforms horizontally after being heated, while the relative positions of the upper support 1511 and the lower support 1522 remain fixed in the vertical direction. The horizontal displacement is related to the temperature change and the coefficient of thermal expansion of the lower pad 152, and can be calculated using the following formula. : ; in, This indicates the coefficient of thermal expansion of the lower pad 152. This indicates the temperature of the lower pad at 152, which is also the target temperature. This indicates the initial temperature, specifically the initial temperature of the lower pad 152. This indicates the thickness of the lower pad 152 at the lower support point 1522, which is the horizontal thickness of the lower pad 152 in its undeformed state. This refers to room temperature, which is the ambient temperature of the wafer thinning equipment when it is not in operation. This temperature value can be a fixed value.

[0069] S23. Calculate the spindle tilt angle after the lower pad 152 is deformed by heat. Because the lower pad 152 changes its lateral thickness after thermal expansion, resulting in horizontal displacement, while the vertical distance between the upper support point 1511 and the lower support point 1522 remains unchanged, and the deformation of the upper pad 151 is ignored in this embodiment, the spindle tilt angle after the lower pad 152 undergoes thermal deformation is... The following formula can be used for calculation: .

[0070] S24. Based on the equality relationship that the difference between the spindle tilt angle after the lower pad 152 undergoes thermal deformation and the initial spindle tilt angle is equal to the compensation angle, the target temperature at which the lower pad 152 undergoes corresponding thermal deformation is calculated.

[0071] Let the compensation angle be denoted as ,use The relationship is calculated in steps S21 and S23 above. By substituting this into the formula, the unique unknown quantity can be calculated. .

[0072] In this embodiment, the compensation angle determined in step S2 can be input into the thermal expansion compensation angle model constructed by this method to obtain the target temperature.

[0073] For ease of understanding, in the above embodiment, the upper pad 151 is made of a material with a low coefficient of thermal expansion, thus the amount of thermal deformation of the upper pad 151 can be ignored. The spindle tilt angle is adjusted only by controlling the temperature change of the lower pad 152, causing the lower pad 152 to deform accordingly. Since the coefficient of thermal expansion of the lower pad 152 is fixed at temperatures far below the Curie temperature, the amount of thermal deformation is fixed when the temperature change is certain. Therefore, the spindle tilt angle can be adjusted by precisely controlling the temperature change of the lower pad 152. Furthermore, by selecting materials for the lower pad 152 with different coefficients of thermal expansion, the adjustment precision of the spindle tilt angle can be controlled, thereby achieving ultra-fine adjustment of the spindle tilt angle.

[0074] In another embodiment, considering that it is difficult to achieve material shrinkage through cooling, and that adjusting the spindle tilt angle may include both increasing and decreasing the tilt angle, the upper pad 151 and the lower pad 152 can both be made of materials that expand when heated. The adjustment of the spindle tilt angle can be achieved by coordinating the upper pad 151 or the lower pad 152. The thermal expansion compensation angle model constructed for this embodiment is as follows: Based on the horizontal displacements of the upper support 1511 and lower support 1522 after the upper pad 151 and lower pad 152 are deformed by heat, the spindle tilt angles of the upper pad 151 and lower pad 152 after heat deformation are calculated. Then, based on the equality that the difference between the spindle tilt angles of the upper pad 151 and lower pad 152 after heat deformation and the initial spindle tilt angle is equal to the compensation angle, the target temperature at which the lower pad 152 and / or the upper pad 151 deforms is determined.

[0075] When the compensation angle is greater than 0°, the spindle tilt angle needs to be increased, which means the thickness of the lower pad 152 needs to be increased so that the thermal deformation of the lower pad 152 is greater than that of the upper pad 151. At this time, the deformation of the lower pad 152 due to thermal expansion can be controlled, and there is no need to control the temperature of the upper pad 151. The temperature of the upper pad 151 is obtained by monitoring. Therefore, the thermal expansion compensation angle model can be used to solve the target temperature at which the lower pad 152 deforms. When the compensation angle is less than 0°, the spindle tilt angle needs to be reduced. This can be achieved by making the upper pad 151 deform more than the lower pad 152 when heated. By controlling the upper pad 151 to deform when heated, there is no need to control the temperature of the lower pad 152. The temperature of the lower pad 152 can be obtained through real-time monitoring. Therefore, the thermal expansion compensation angle model can be used to solve for the target temperature at which the upper pad 151 deforms.

[0076] In one embodiment, the method for calculating the spindle tilt angle of the upper pad 151 and lower pad 152 after thermal deformation, based on the horizontal displacements at the upper support point 1511 and lower support point 1522 respectively, after the upper pad 151 and lower pad 152 are deformed by heat, includes: First, based on the thermal expansion coefficient, temperature change, and thickness of the upper pad 151 at the upper support 1511, calculate the horizontal displacement of the upper pad 151 at the upper support 1511 after thermal deformation; then, based on the thermal expansion coefficient, temperature change, and thickness of the lower pad 152 at the lower support 1522, calculate the horizontal displacement of the lower pad 152 at the lower support 1522 after thermal deformation; finally, based on the difference between the thickness of the lower pad 152 at the lower support 1522 and the thickness of the upper pad 151 at the upper support 1511 after thermal deformation, the initial distance between the upper support 1511 and the upper surface of the lower pad 152, and the length of the lower pad 152 along the main shaft 12, solve for the main shaft tilt angle after deformation of the lower pad 152 or the upper pad 151.

[0077] Considering the thermal deformation of both the upper pad 151 and the lower pad 152, one embodiment of this application provides a method for constructing a thermal expansion compensation angle model, referring to... Figure 9 The flowchart for this method of constructing the thermal expansion compensation angle model includes the following steps: S31. Determine the initial principal spindle tilt angle; The initial spindle tilt angle is the tilt angle between the spindle 12 and the axis of the adsorption platform 20 in the initial state, which is also the tilt angle between the spindle 12 and the axis of the wafer 50. The initial state is the state in which neither the upper pad 151 nor the lower pad 152 has deformed, which can also be understood as the state at the ambient temperature or room temperature of the wafer thinning equipment.

[0078] In this embodiment, the initial spindle tilt angle It can be obtained based on the following relation: ; in, This indicates the thickness of the lower pad at the lower support point 1522 (the horizontal thickness of the lower pad 152 before thermal deformation). This indicates the thickness of the upper pad 151 at the upper support point 1511 (the horizontal thickness of the upper pad 151 before thermal deformation). This indicates the initial distance between the upper fulcrum 1511 and the upper surface of the lower pad 152; This indicates the length of the lower pad 152 along the main shaft 12.

[0079] This embodiment is illustrated by taking the example of the lower pad 152 being fully inserted between the feed mechanism 14 and the spindle seat 13 (that is, the lower surface of the lower pad 152 and the lower support point are on the same plane). If the lower pad 152 is partially inserted between the feed mechanism 14 and the spindle seat 13, then the corresponding... This indicates the length of the portion of the lower pad 152 inserted between the feed mechanism 14 and the spindle seat 13 along the direction of the spindle 12. If the lower pad 152 is a wedge-shaped plate, ensure that the entire wedge-shaped portion is inserted. The lowest end of the portion of the lower pad 152 inserted between the feed mechanism 14 and the spindle seat 13 is the non-wedge-shaped portion.

[0080] S32. Calculate the horizontal displacement of the upper support 1511 after the upper pad 151 is deformed by heat. After being heated, the upper pad 151 deforms horizontally, while the upper support point 1511 and the lower support point 1522 remain fixed in their relative positions in the vertical direction. The horizontal displacement of the upper pad 151 is related to its temperature change and coefficient of thermal expansion, and can be calculated using the following formula. : ; in, This indicates the coefficient of thermal expansion of the upper pad 151. This indicates the temperature of the upper pad 151. This indicates the initial temperature, which is the initial temperature of the upper pad 151 and the lower pad 152, that is, the ambient temperature when the wafer thinning equipment is not started. This temperature value can be a fixed value. S33: Calculate the horizontal displacement at the lower support point 1522 after the lower pad 152 is deformed by heat; After being heated, the lower pad 152 deforms horizontally, while the upper support 1511 and the lower support 1522 remain fixed in their relative positions in the vertical direction. The horizontal displacement of the lower pad 152 is related to its temperature change and coefficient of thermal expansion, and can be calculated using the following formula. : ; in, This indicates the coefficient of thermal expansion of the lower pad 152. This indicates the temperature of the lower pad 152.

[0081] S34: Calculate the spindle tilt angle after the upper pad 151 and lower pad 152 are deformed by heat; The spindle tilt angle after the upper pad 151 and lower pad 152 are deformed by heat The following formula can be used for calculation: .

[0082] in, This indicates the thickness of the lower pad 152 at the lower support point 1522 after thermal deformation. This indicates the thickness at the upper support point 1511 after the upper pad 151 is deformed by heat.

[0083] S35: Based on the equality relationship that the difference between the spindle tilt angle after the upper pad 151 and the lower pad 152 are deformed by heat and the initial spindle tilt angle is equal to the compensation angle, the target temperature at which the lower pad 152 or the upper pad 151 deforms is determined.

[0084] Due to the thermal deformation of the upper pad 151 and the lower pad 152, the spindle tilt angle relative to the initial principal axis tilt angle The difference is equal to the compensation angle (denoted as ). ), The results calculated in steps S31 and S34 Substituting into this formula, where, in Δ θ y When the temperature is greater than 0, it is necessary to control the thermal expansion of the lower pad 152 to increase the spindle tilt angle. Therefore, temperature control of the upper pad 151 is not required. This can be obtained through real-time monitoring, such as through a temperature sensor. During the wafer thinning process, the grinding wheel 11 contacts the wafer 50, generating grinding heat. This heat is conducted from the grinding wheel 11 to the spindle 12, causing the temperature of the upper pad 151 during operation to be higher than the ambient temperature. Therefore, even without temperature control of the upper pad 151, its temperature will be higher than the ambient temperature, resulting in a temperature difference. In this case, the thermal expansion compensation angle model constructed in this embodiment can be used to solve for the target temperature at which the lower pad 152 deforms. .

[0085] Similarly, in Δ θ y When the temperature is less than 0, it is necessary to control the thermal expansion of the upper pad 151 to reduce the spindle tilt angle, and temperature control of the lower pad 152 is not required. This can be obtained through real-time monitoring; the temperature of the lower pad 152 during operation will be higher than room temperature, which means... Therefore, even without temperature control of the lower pad 152, the lower pad 152 will still be above room temperature, resulting in a temperature difference. In this case, the thermal expansion compensation angle model constructed in this embodiment can be used to solve for the target temperature at which the upper pad 151 deforms. .

[0086] It should be noted that, from the perspective of unidirectional thermal expansion, since both the upper pad 151 and the lower pad 152 are located between the slider and the wing plate, the deformation of the upper pad 151 and the lower pad 152 can be coordinated to adjust the spindle tilt angle. Controlling the thermal deformation of the lower pad 152 can increase the spindle tilt angle, and conversely, controlling the thermal deformation of the upper pad 151 can decrease the spindle tilt angle. Considering that heating to expand the adjusting pad is easier to achieve and has higher control precision than cooling to shrink the adjusting pad, this embodiment of the application can use the thermal expansion characteristics to adjust the tilt angle in both cases of increasing and decreasing the spindle tilt angle. By controlling the temperature of a single pad individually to adjust the spindle 12, both adjustment efficiency and adjustment precision can be improved.

[0087] In a non-limiting way, this embodiment utilizes the characteristic that temperature rise is easier to control and has higher precision than temperature fall, strategically selects the adjustment object, and avoids adjustment lag or overshoot caused by factors such as unstable heat dissipation rate and ambient temperature interference during the cooling process, so as to ensure the stability of the temperature reaching the target value and thus ensure the consistency of the pad deformation.

[0088] In non-limiting cases, for scenarios where wafer thinning temperature is sensitive, the thermal expansion control of the lower pad 152 may cause heat to be conducted to the wafer 50, leading to increased grinding temperature and affecting the process results of the wafer 50. For adjusting the spindle tilt angle in this type of wafer thinning, a combined adjustment mode of cooling or moderately heating the lower pad 152 and adjusting the upper pad 151 can be considered.

[0089] S4: Adjust the temperature of the adjusting shim between the spindle seat 13 and the feed mechanism 14 to the target temperature, so that the adjusting shim deforms accordingly based on the temperature change, thereby adjusting the spindle tilt angle.

[0090] After the target temperature is calculated, the temperature of the temperature control component can be controlled to adjust the temperature of the adjustment pad to reach the target temperature. This causes the adjustment pad to deform based on the temperature change, thereby adjusting the distance between the slider and the wing plate, which in turn changes the spindle tilt angle.

[0091] This embodiment utilizes the thermal expansion characteristics of the adjusting shim. When the spindle tilt angle needs to be adjusted, the temperature change of the adjusting shim is controlled to cause the adjusting shim to deform accordingly based on the temperature change, thereby achieving the adjustment of the spindle tilt angle. Since the coefficient of thermal expansion of the adjusting shim is fixed, the amount of thermal deformation is also fixed when the temperature change is determined. Therefore, by precisely controlling the temperature change of the adjusting shim, the adjusting shim can produce the required amount of deformation, thereby achieving ultra-fine adjustment of the spindle tilt angle.

[0092] Compared to traditional mechanical adjustment, this application avoids the inherent step-like changes of mechanical adjustment, thus enabling more precise and stable stepless fine-tuning of the spindle tilt angle. It also avoids the wear of the adjustment pads caused by mechanical adjustment, allowing for more accurate control of the wafer grinding surface shape. It should be noted that mechanical adjustment can lead to wear of the adjustment components, affecting adjustment accuracy, and can also cause metal wear contamination, resulting in short circuits at device contacts and impacting wafer processing yield.

[0093] Furthermore, the automated control of the temperature control components greatly reduces the uncertainties of manual operation, significantly reduces the dependence of the adjustment results on the operator's skills, reduces adjustment operation errors, and further improves the precision of wafer grinding.

[0094] This application can monitor and adjust the wafer surface shape in real time, realizing closed-loop control of the wafer grinding surface shape characteristics, eliminating the accumulation of wafer surface shape deviation caused by the delay of manual mechanical adjustment, and effectively improving the wafer grinding accuracy.

[0095] Traditional spindle tilt adjustment relies heavily on hard contact between mechanical parts, and frequent adjustments over a long period can easily lead to wear and tear on these parts, thereby increasing the frequency and cost of equipment maintenance. In contrast, this embodiment indirectly adjusts the spindle tilt by adjusting the thermal expansion and deformation of the shim plate, eliminating the need for hard friction between mechanical parts. This significantly reduces the mechanical wear of core components such as the spindle 12 and grinding wheel 11, and extends the maintenance cycle of the wafer grinding equipment.

[0096] refer to Figure 10 This is a schematic diagram of a grinding wheel grinding wafer provided in an embodiment of this application. When the grinding wheel 11 grinds the wafer 50, the arc formed by the contact portion between the grinding wheel 11 and the wafer 50 is the grinding line OM. One end O of the grinding line is located at the center of the wafer 50, and the other end M is located at the edge of the wafer 50. The compensation angle of the spindle 12 can be divided into two dimensions: a first dimension compensation angle and a second dimension compensation angle. The first dimension is the front-back direction, more specifically, the radial direction of the wafer 50 formed by the line connecting the two ends of the grinding line OM. The second dimension is the left-right direction, more specifically, the horizontally extending direction perpendicular to the first dimension. As mentioned above, the adjusting shim is disposed between the feed mechanism 14 and the spindle seat 13. Therefore, the spindle tilt angle adjusted based on the thermal deformation characteristics of the adjusting shim is the tilt angle of the spindle 12 in the first dimension. The adjustment of the spindle 12 tilt angle in the second dimension is not specifically limited in this application.

[0097] In this embodiment, determining the compensation angle of the principal axis 12 based on surface features may specifically include: Convexity δ 1 and fullness δ2. Input the arc surface model and obtain the current principal axis 12 in the first dimension tilt angle and the second dimension tilt angle; that is, in this embodiment, the principal axis tilt angle includes the first dimension tilt angle and the second dimension tilt angle, and the arc surface model is used to characterize the correspondence between the surface features and the principal axis 12 in the first dimension tilt angle and the second dimension tilt angle.

[0098] The difference between the first-dimensional tilt angle and the first-dimensional target tilt angle is determined as the compensation angle.

[0099] Based on this arc surface model, a quantitative compensation angle can be obtained, thereby enabling precise adjustment and control of the tilt angle. Regarding the compensation angle, this embodiment utilizes temperature-based adjustment to deform the adjustment pad, achieving adjustment. This method enables ultra-fine adjustment and closed-loop control of the spindle tilt angle, improving the adjustment efficiency and accuracy. Furthermore, since the adjustment temperature range is far below the Curie temperature of the spindle material, it does not affect the elastic modulus of the spindle material or the stiffness of the spindle, thus significantly improving the precision of wafer grinding.

[0100] In another embodiment of this application, the difference between the first-dimensional tilt angle and the first-dimensional target tilt angle can be determined as the first-dimensional compensation angle, and the difference between the second-dimensional tilt angle and the second-dimensional target tilt angle can also be determined as the second-dimensional compensation angle. This embodiment can further decouple concavity and convexity based on the adjustment relationship between tilt angle and surface features. δ 1 and fullness δ 2. To adjust the tilt angle of the principal axis 12 in the first dimension and / or the tilt angle in the second dimension. The relationship between the tilt angle and the surface feature adjustment includes: changes in the tilt angle in the first dimension affect the concavity / convexity. δ 1 and fullness δ The change in the average value and the change in the tilt angle in the second dimension affect the fullness. δ 2. Variation, Concavity / Concavity δ 1. No change. In this embodiment, the tilt angle of the main axis 12 in the first dimension is first adjusted based on the first dimension compensation angle, and then the tilt angle of the main axis 12 in the second dimension is adjusted based on the second dimension compensation angle. Specifically, it includes: Determine the concavity / convexity δ If 1 is less than the first threshold, then perform a fullness check. δ 2. If the value is less than the second threshold, adjust the tilt angle of the spindle 12 in the first dimension based on the first dimension compensation angle, and then continue to perform the acquisition operation after grinding for a preset time; wherein, adjusting the tilt angle of the spindle 12 in the first dimension based on the first dimension compensation angle can be achieved by the method of this application, which is to adjust the tilt angle of the spindle 12 in the first dimension by controlling the temperature change of the adjustment pad, so that the adjustment pad produces a corresponding deformation based on the temperature change.

[0101] Judging fullness δIf 2 is less than the second threshold, then after grinding for a preset time, the acquisition operation will be triggered to continue. Otherwise, the tilt angle of the spindle 12 in the second dimension will be adjusted based on the second dimension compensation angle, and then after grinding for a preset time, the acquisition operation will be triggered to continue.

[0102] The first-dimensional target tilt angle and the second-dimensional target tilt angle can be determined based on the target surface features, that is, based on the target concavity and convexity, the target fullness and the arc surface model.

[0103] This embodiment utilizes the adjustment relationship between tilt angle and surface features to decouple concavity and convexity. δ 1 and fullness δ 2, making the concavity and convexity δ 1 and fullness δ 2. The coupling is no longer in place, avoiding blind and inefficient adjustments to the tilt angle of the spindle 12 in two dimensions, through concavity and convexity. δ 1 and fullness δ 2. Precise compensation angles can be obtained in two dimensions separately. First, the tilt angle in the first dimension is adjusted. Due to the change in the tilt angle in the first dimension, the concavity and convexity are adjusted. δ 1 and fullness δ Both dimensions change, therefore, when adjusting the tilt angle of the first dimension, the concavity and convexity can be changed simultaneously. δ 1 and fullness δ 2. Adjusting the tilt angle in the first dimension can at least ensure the concavity / convexity. δ 1. Meet the requirements, or make the concavity / convexity... δ 1 and fullness δ If both requirements are met, there is no need to perform a second-dimensional tilt angle adjustment, effectively improving the tilt angle adjustment efficiency and thus ensuring wafer grinding efficiency. Furthermore, when adjusting the second-dimensional tilt angle, the fullness is achieved by adjusting the second-dimensional tilt angle. δ 2. Meet the requirements while maintaining the already adjusted unevenness. δ 1. Unaffected, thus avoiding the need to assess convexity / concavity through the first and second dimension tilt angles. δ 1 and fullness δ The repetitive and inefficient adjustments of step 2 are eliminated by this decoupled adjustment method, which has a clear and specific adjustment target and a reasonable and effective adjustment sequence. This not only improves the efficiency of tilt adjustment but also reduces the impact on wafer roughness during the adjustment process. δ 1 and fullness δ 2. Improved control precision leads to enhanced TTV precision in wafer grinding.

[0104] One embodiment of this application provides a method for constructing an arc surface model, referencing... Figure 10 It includes the following steps: First, taking the center O' of the grinding wheel as the origin and the lower surface of the grinding wheel as the reference point... With the extension direction of the main shaft 12 as In a coordinate system (not shown), construct the grinding line OM. coordinate( :

[0105] in, , Where is the radius of the grinding wheel; The radius of the wafer; Secondly, a coordinate transformation is performed to obtain the tilt angle of principal axis 12 along the second dimension. and the tilt angle along the first dimension The coordinates of the subsequent grinding line OM ( x , y , z ).

[0106]

[0107] in, This is the transformation matrix for the second dimension. This is the transformation matrix for the first dimension.

[0108] ,

[0109] Next, solve for the center point O of the grinding wire OM around the wafer. Rotation The following represents the arc coordinates of the wafer surface grinding morphology. , .

[0110] Among them, the circular arc rotation matrix ; Coordinates of wafer center point O ; Finally, the arc surface can be constructed using software such as Matlab based on the arc surface coordinate expression. The resulting arc surface is the wafer surface shape. That is, the grinding wheel grinds the wafer based on the grinding line. The arc surface obtained after grinding 360° is the wafer surface shape. Then, the surface shape features of the wafer can be obtained based on the arc surface, thereby establishing the relationship between the surface shape features and the tilt angle of the principal axis 12 in the first and second dimensions.

[0111] In this embodiment, the arc surface model can be pre-constructed, and then the tilt angle of the current principal axis 12 along the second dimension can be solved in reverse based on the surface features of the current wafer. and the tilt angle along the first dimension Thus, it is possible to base the tilt angle on the first dimension. Obtaining the compensation angle provides an accurate basis for adjusting the spindle tilt angle, effectively improving the accuracy of spindle tilt angle adjustment, thereby improving the accuracy of wafer grinding.

[0112] Verification has shown that the thinning method of this application can achieve a spindle tilt angle control accuracy of 0.0001° and a wafer TTV accuracy of less than 1μm after grinding.

[0113] This application achieves closed-loop control of the surface features of wafer grinding, eliminating the delay problem of manual mechanical adjustment and the error caused by human operation, effectively improving the overall efficiency of wafer grinding and the TTV accuracy of wafer grinding.

[0114] This application utilizes the thermal expansion and contraction properties of the adjusting pad. By precisely controlling the temperature change of the adjusting pad, corresponding deformation occurs, thereby achieving ultra-fine adjustment of the spindle tilt angle. This effectively improves the precision of spindle tilt angle adjustment, enabling effective control of the surface features during wafer grinding and improving the TTV (Total Television Value) accuracy of wafer grinding. This provides technical support for ultra-high density semiconductor stacking processes. Compared with traditional mechanical adjustment methods, this application avoids adjustment errors and equipment failures caused by wear and loosening of mechanical parts, improving the stability and reliability of the equipment.

[0115] In a non-limiting embodiment, this application also provides a method for wafer grinding, comprising: determining a wafer surface shape; inputting the wafer surface shape into an arc surface model to determine a grinding parameter adjustment method; the grinding parameter adjustment method includes: the proportion and adjustment amount of different adjustment methods; the different adjustment methods include: adjusting the temperature of the lower pad 152, adjusting the temperature of the upper pad 151, and adjusting the position of the worktable 30.

[0116] Reference Figure 11 The diagram shown is a structural block diagram of a thinning device provided in one embodiment of this application, including: a feature acquisition unit 110, a compensation angle determination unit 111, a target temperature determination unit 112, and a tilt angle adjustment unit 113.

[0117] The feature acquisition unit 110 is used to acquire the surface features of the wafer during the wafer grinding process of the wafer thinning equipment; The compensation angle determination unit 111 is used to determine the compensation angle of the spindle 12 based on the surface features. The spindle 12 is connected to the grinding wheel 11 for grinding the wafer to drive the grinding wheel 11 to rotate, and the spindle 12 is located in the spindle seat 13. The target temperature determination unit 112 is used to input the compensation angle into the thermal expansion compensation angle model to obtain the output target temperature. The tilt angle adjustment unit 113 is used to adjust the temperature of the adjustment pad between the spindle seat 13 and the feed mechanism 14 to the target temperature, so that the adjustment pad will deform accordingly based on the temperature change, thereby adjusting the spindle tilt angle.

[0118] The further functions of the thinning device in this embodiment refer to the thinning method in the embodiment of this application, and will not be repeated here.

[0119] See Figure 12 , Figure 12 This is a schematic block diagram of an electronic device provided according to an embodiment of this application. Figure 12 The electronic device 600 in this embodiment may include one or more processors 601, one or more input devices 602, one or more output devices 603, and one or more memories 604. The processors 601, input devices 602, output devices 603, and memories 604 communicate with each other via a communication bus 605. The memory 604 stores computer programs, including program instructions. The processor 601 executes the program instructions stored in the memory 604. The processor 601 is configured to invoke the program instructions to perform the functions of each unit in the above-described device embodiments, for example... Figure 11 The functions of the feature acquisition unit 110, compensation angle determination unit 111, target temperature determination unit 112, and tilt angle adjustment unit 113 are shown.

[0120] It should be understood that, in the embodiments of this application, the processor 601 may be a central processing unit, and the processor may also be other general-purpose processors, digital signal processors, application-specific integrated circuits, etc.

[0121] Input device 602 may include a touchpad, etc., and output device 603 may include a display, speaker, etc.

[0122] The memory 604 may include read-only memory or random access memory and provide instructions and data to the processor 601. A portion of the memory 604 may also include non-volatile random access memory.

[0123] In specific implementations, the processor 601, input device 602, and output device 603 described in the embodiments of this application can execute the implementation method described in the thinning method provided in the embodiments of this application, or they can execute the implementation method of the electronic device described in the embodiments of this application, which will not be repeated here.

[0124] In another embodiment of this application, a computer-readable storage medium is provided. This computer-readable storage medium stores a computer program, which includes program instructions. When executed by a processor, the program instructions implement all or part of the processes in the methods described above. Alternatively, the computer program can instruct related hardware to perform these processes. The computer-readable medium may include any entity or device capable of carrying computer program code, such as a USB flash drive, a portable hard drive, a computer memory, or a read-only memory.

[0125] The computer-readable storage medium can be an internal storage unit of the electronic device in any of the foregoing embodiments, such as a hard disk or memory of the electronic device. The computer-readable storage medium can also be an external storage device of the electronic device, such as a plug-in hard disk, smart memory card, etc., provided on the electronic device.

[0126] This application provides a computer program product, which includes computer-executable instructions or a computer program. The computer-executable instructions or computer program are stored in a computer-readable storage medium. The processor of an electronic device reads the computer-executable instructions from the computer-readable storage medium and executes the computer-executable instructions, causing the electronic device to perform the implementation described in the thinning method provided in this application.

[0127] It should be noted that, depending on the implementation needs, the various components / steps described in the embodiments of this application can be broken down into more components / steps, or two or more components / steps or parts of the operation of components / steps can be combined into new components / steps to achieve the purpose of the embodiments of this application.

[0128] The above are merely specific embodiments of this application, but the scope of protection of this application is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in this application, and these modifications or substitutions should all be covered within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A wafer thinning equipment, characterized in that, include: Grinding device, adsorption platform and temperature control unit; The adsorption platform is used to support the wafer and drive the wafer to rotate. The grinding device is raised and lowered above the adsorption platform, and the grinding device includes: a spindle for driving the grinding wheel to rotate; The grinding device further includes: a spindle seat, a feed mechanism, and an adjusting plate; the spindle is rotatably coaxially disposed within the spindle seat; the spindle seat is connected to the feed mechanism; the adjusting plate is at least partially inserted between the feed mechanism and the spindle seat; the adjusting plate is provided with a temperature regulating component; The temperature control unit is electrically connected to the temperature adjustment component and is used to determine the spindle compensation angle based on the surface features of the wafer. The compensation angle is input into the thermal expansion compensation angle model to obtain the output target temperature. The temperature of the adjustment pad is adjusted to reach the target temperature by adjusting the temperature of the temperature adjustment component, so that the adjustment pad deforms accordingly based on the temperature change to adjust the spindle tilt angle.

2. The wafer thinning equipment according to claim 1, characterized in that, The spindle seat includes a tubular main body and outwardly extending wing plates on its left and right sides; the feeding mechanism includes a slide rail arranged in a vertical direction and a slider that moves vertically along the slide rail. The adjusting pad is at least partially inserted between the slider and the wing plate.

3. The wafer thinning equipment according to claim 2, characterized in that, The adjusting pad includes an upper pad and a lower pad, which are inserted downwards and upwards respectively between the slider and the wing plate.

4. The wafer thinning equipment according to claim 3, characterized in that, The temperature regulating component is provided in at least one of the upper pad and the lower pad.

5. The wafer thinning apparatus according to any one of claims 1 to 4, characterized in that, The temperature regulating component includes: A temperature sensor and at least one temperature control actuator are provided, both of which are electrically connected to the temperature control unit. The temperature sensor is used to monitor the temperature of the regulating pad.

6. The wafer thinning apparatus according to claim 3, characterized in that, The thermal expansion compensation angle model is constructed as follows: Based on the horizontal displacement of the lower support point after the lower pad is deformed by heat, the spindle tilt angle of the lower pad after deformation is calculated. Based on the equality that the difference between the spindle tilt angle of the lower pad after deformation and the initial spindle tilt angle is equal to the compensation angle, the target temperature at which the lower pad undergoes deformation is determined; or Based on the horizontal displacements of the upper and lower pads at the upper and lower supports respectively after thermal deformation, the spindle tilt angles of the upper and lower pads after thermal deformation are calculated. Based on the equality relationship that the difference between the spindle tilt angles of the upper and lower pads after thermal deformation and the initial spindle tilt angle is equal to the compensation angle, the target temperature at which the deformation occurs in the lower or upper pad is determined.

7. A thinning method, characterized in that, include: To obtain the surface features of the wafer during the wafer grinding process using a wafer thinning equipment; The compensation angle of the spindle is determined based on the surface features. The spindle is connected to the grinding wheel for grinding the wafer to drive the grinding wheel to rotate, and the spindle is located in the spindle seat. Input the compensation angle into the thermal expansion compensation angle model to obtain the output target temperature; The temperature of the adjusting shim between the spindle seat and the feed mechanism is adjusted to the target temperature, so that the adjusting shim deforms accordingly based on the temperature change, thereby adjusting the spindle tilt angle.

8. The thinning method according to claim 7, characterized in that, The adjusting pad includes an upper pad and a lower pad that are inserted downwards and upwards respectively between the spindle seat and the feed mechanism. The thermal expansion compensation angle model is constructed as follows: based on the horizontal displacement of the lower pad at the lower support point after thermal deformation, the spindle tilt angle after the lower pad is deformed is calculated. Based on the equality relationship that the difference between the spindle tilt angle after the lower pad is deformed and the initial spindle tilt angle is equal to the compensation angle, the target temperature at which the lower pad undergoes the deformation is solved.

9. The thinning method according to claim 7, characterized in that, The adjusting pads include an upper pad and a lower pad that are inserted downwards and upwards respectively between the spindle seat and the feed mechanism. The thermal expansion compensation angle model is constructed as follows: based on the horizontal displacement of the upper and lower pads at the upper and lower support points after thermal deformation, the spindle tilt angle after thermal deformation of the upper and lower pads is calculated. Based on the equality relationship that the difference between the spindle tilt angle after thermal deformation of the upper and lower pads and the initial spindle tilt angle is equal to the compensation angle, the target temperature at which the deformation occurs in the lower or upper pads is solved.

10. The thinning method according to claim 9, characterized in that, The thermal expansion compensation angle model is constructed as follows: The horizontal displacement of the upper pad at the upper support point after thermal deformation is calculated based on the thermal expansion coefficient of the upper pad, temperature change, and thickness of the upper pad at the upper support point. The horizontal displacement of the lower pad at the lower support point after thermal deformation is calculated based on the thermal expansion coefficient of the lower pad, temperature change, and thickness of the lower pad at the lower support point. Based on the difference between the thickness of the lower pad at the lower support point after thermal deformation and the thickness of the upper pad at the upper support point after thermal deformation, the initial distance between the upper support point and the upper surface of the lower pad, and the length of the lower pad along the main axis, the main axis tilt angle of the lower or upper pad after thermal deformation is calculated.

11. The thinning method according to claim 9, characterized in that, The thinning method includes: When the compensation angle is greater than 0°, the target temperature at which the lower pad produces the deformation is calculated using the thermal expansion compensation angle model, and the temperature of the lower pad is adjusted to the target temperature. When the compensation angle is less than 0°, the target temperature at which the upper pad produces the deformation is calculated using the thermal expansion compensation angle model, and the temperature of the upper pad is adjusted to the target temperature.

12. The thinning method according to any one of claims 7 to 11, characterized in that, The determination of the compensation angle of the principal axis based on the surface features includes: The surface features are input into the arc surface model to obtain the current principal axis tilt angle; the arc surface model is based on the grinding line structure formed when the grinding wheel contacts the wafer, and the arc surface model is used to characterize the correspondence between the surface features and the principal axis tilt angle; The difference between the current spindle tilt angle and the target tilt angle is determined as the compensation angle.

13. The thinning method according to claim 12, characterized in that, The current spindle tilt angle output includes: a first-dimensional tilt angle and a second-dimensional tilt angle. The contact portion between the grinding wheel and the wafer forms an arc-shaped grinding line. One end of the grinding line is located at the center of the wafer, and the other end is located at the edge of the wafer. The first dimension is the wafer radius direction where both ends of the grinding line are located, and the second dimension is a horizontally extending direction perpendicular to the first dimension. The step of determining the difference between the current spindle tilt angle and the target tilt angle as the compensation angle includes: The difference between the first dimension tilt angle and the first dimension target tilt angle is determined as the compensation angle.

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