Method for preparing curved crystal

Abstract

The present invention is applicable to the technical field of preparing curved surface bent crystals, and provides a method for preparing curved surface bent crystals, comprising the following steps: providing a die and a wafer to be processed, the die having a first curved surface that matches the curved surface of the target curved surface bent crystal; obtaining the curved surface parameters of the target curved surface bent crystal, the curved surface parameters including the curved surface radius and the curved surface curvature; applying a first pressure to two first edges of the wafer extending along a first direction, so that the first edges fit with the first curved surface, until the first edges form a curved surface structure that matches the shape of the corresponding area in the first curved surface; there are multiple contact points distributed along the meridian direction between the first pressure and the wafer, and the first direction is a direction corresponding to the meridian direction of the target curved surface bent crystal; applying a second pressure to the wafer, so that a side of the wafer close to the first curved surface fits tightly with the first curved surface, until the wafer forms a target curved surface structure that matches the first curved surface. The method for preparing curved surface bent crystals provided by the present invention can effectively improve the yield rate.

Description

Technical Field

[0001] The present invention belongs to the technical field of curved surface bent crystal preparation, and in particular relates to a curved surface bent crystal preparation method. Background Art

[0002] Curved spectroscopic wafers (hereinafter referred to as curved crystals) are usually used in the X-ray field. They can focus the X-ray light incident on the wafer at the Bragg angle after diffraction. The diffracted light intensity is much stronger than that of a flat wafer, so curved crystals can achieve high light collection efficiency. However, current curved crystals are usually made by bending a single crystal. Since the above-mentioned single crystals are generally formed of brittle materials such as mica, silicon, germanium, LiF, and graphite, the wafers are fragile when preparing curved crystals, resulting in a low yield of curved crystals.

[0003] Therefore, it is very necessary to develop a method for preparing curved crystals that can improve the yield of curved crystals. Summary of the invention

[0004] The purpose of the present invention is to provide a method for preparing a curved surface bent crystal, aiming to solve the technical problem of low yield of curved surface bent crystals in the prior art.

[0005] The present invention is implemented as follows: a method for preparing a curved crystal, comprising the following steps:

[0006] Providing a concave mold and a wafer to be processed, wherein the concave mold has a first curved surface adapted to the curved surface of a target curved wafer;

[0007] Acquire the surface parameters of the target curved crystal, wherein the surface parameters include the surface radius and the surface curvature;

[0008] Applying a first pressure to two first edges of the wafer extending along a first direction so that the first edges fit the first curved surface until the first edges form a curved surface structure that matches the shape of a corresponding area in the first curved surface; wherein the first pressure has a plurality of contact points distributed along a meridian direction with the wafer, and the first direction is a direction corresponding to the meridian direction of the target curved surface bent crystal;

[0009] A second pressure is applied to the wafer so that a side of the wafer close to the first curved surface is closely fitted to the first curved surface until the wafer forms a target curved surface structure matching the first curved surface.

[0010] In an optional embodiment, applying the second pressure to the entire wafer comprises the following steps:

[0011] Applying a third pressure distributed at intervals to the entire force-bearing surface of the wafer until the force-bearing area of ​​the wafer forms a curved surface structure that matches the shape of the corresponding area of ​​the first curved surface;

[0012] A fourth pressure is applied to the entire force-bearing surface of the wafer until the entire force-bearing surface of the wafer is attached to the first curved surface and forms the target curved surface structure; the contact area between the fourth pressure and the wafer is greater than or equal to the area of ​​the force-bearing surface of the wafer.

[0013] In an optional embodiment, the applying of the first pressure to the two first edges of the wafer extending along the first direction and the applying of the third pressure distributed at intervals to the entire force-bearing surface of the wafer are achieved by a pre-pressing bending device;

[0014] The pre-pressing and bending device includes the concave mold and the convex mold, the convex mold has a plurality of deformation strips spaced apart along the first direction, the deformation strips are located on the side of the wafer away from the concave mold, and can be deformed under the action of the first pressure and the third pressure to change from a first state adapted to the initial shape of the wafer to a second state adapted to the shape of the corresponding area of ​​the first curved surface.

[0015] In an optional embodiment, the male mold includes a bracket, the deformation strip and a force-applying module corresponding to the deformation strip one by one; the force-applying module is installed on the bracket and is located on the side of the deformation strip away from the female mold, and is used to apply reciprocating pressure to the corresponding deformation strip; each of the force-applying modules includes a plurality of force-applying units arranged at intervals along a second direction; the two ends of the deformation strip in the second direction are respectively connected to the female mold or the bracket for sliding along the second direction, and the second direction is a direction corresponding to the sagittal direction of the target curved surface bent crystal.

[0016] In an optional embodiment, the force-applying unit includes a threaded member threadedly connected to the bracket;

[0017] The pre-pressing and bending device further comprises a first explosion-proof film, and the first explosion-proof film is used to be attached to the back side of the wafer;

[0018] And / or, the pre-stressing and bending device further comprises a strain gauge, wherein the strain gauge is located between the concave mold and the convex mold and is used to be attached to the wafer to monitor the strain of the wafer.

[0019] In an optional embodiment, the applying of the fourth pressure to the entire force-bearing surface of the wafer is achieved by a final pressure bending device;

[0020] The final pressure bending device includes the concave mold, a pressure component, a second explosion-proof membrane and a protective film. The pressure component has a pressure portion, which is located on the side of the wafer away from the first curved surface. The pressure portion is used to apply pressure to the wafer toward the first curved surface so that the surface of the wafer close to the first curved surface is tightly fitted with the first curved surface. The second explosion-proof membrane is used to be attached to the back side of the wafer, and the protective film is used to be attached to the reflective surface of the wafer.

[0021] In an optional embodiment, the pressure applying portion includes a pressure plate and a flexible member, wherein the flexible member is mounted on a surface of the pressure plate opposite to the first curved surface and is used to contact the wafer;

[0022] The flexible member is a soft rubber member; in an initial state, the projection area of ​​the flexible member on the first curved surface is smaller than the projection area of ​​the pressure plate on the first curved surface; under pressure, the flexible member can fill the entire space between the pressure plate and the wafer.

[0023] In an optional embodiment, the target curved crystal is a double-curved crystal, and the method for preparing a curved crystal further comprises the following steps between applying a first pressure to two first edges of the wafer extending along the first direction and applying a second pressure to the wafer:

[0024] A fifth pressure is applied to two second edges of the wafer that are opposite to each other in the first direction, so that the second edges fit the first curved surface until the second edges form a curved surface structure that matches the shape of the corresponding area in the first curved surface.

[0025] In an optional embodiment, providing a concave mold and a wafer to be processed comprises the following steps:

[0026] Providing a concave mold and a wafer to be cut;

[0027] Obtain the arc length of each side and the center line length of the target curved crystal;

[0028] According to the arc lengths of the sides and the center line length of the target curved wafer, processing parameters of the flat wafer after flattening are obtained, wherein the processing parameters include the arc lengths of the sides and the center line length of the flat wafer;

[0029] The wafer to be cut is cut according to the processing parameters to obtain a wafer to be processed.

[0030] In an optional embodiment, the method for preparing a curved crystal further comprises the following steps:

[0031] providing a substrate;

[0032] The wafer formed with the target curved surface structure is bonded to the substrate by glue having a coefficient of expansion close to that of the wafer.

[0033] The technical effect of the present invention relative to the prior art is as follows: the method for preparing a curved surface curved crystal provided by the embodiment of the present invention changes the inherent way of directly applying pressure to the wafer through a convex mold and a concave mold with a fixed shape in the traditional technology to achieve the preparation of the target curved surface curved crystal, and provides a new method for preparing a curved surface curved crystal. During preparation, a first pressure is first applied to two first edges of the wafer extending along a first direction so that the corresponding edge (i.e., the first edge) of the wafer fits with the first curved surface to obtain a single curved surface curved crystal, and then the wafer is pressed as a whole to obtain the final target curved surface curved crystal. Among them, there are multiple contact points distributed along the meridian direction between the first pressure and the wafer, so that the point pressure applied by the convex mold on the wafer is converted into a linear pressure formed by multiple action points, which can effectively reduce the stress on the local wafer during the preparation of the single curved surface curved crystal, thereby reducing the internal strain of the wafer, reducing the risk of multiple contact points between the wafer and the concave mold during processing, and improving the yield rate of the target curved surface curved crystal. At the same time, the target curved surface bent crystal is completed by applying pressure twice, which can further reduce the internal strain of the wafer during processing, reduce the risk of breakage at multiple contact points between the wafer and the die during processing, and improve the yield of the target curved surface bent crystal.

[0034] The method for preparing curved crystals provided by the embodiment of the present invention can realize the preparation of single curved crystals, double curved crystals, etc., and is suitable for the preparation of curved crystals with small curvatures. The finished products have a high yield and can be widely used in the fields of X-ray diffraction (XRD), X-ray reflectometry (XRR), microfocus fluorescence analysis (XRF), total reflection fluorescence analysis (TXRF), etc. In addition, since the current preparation technology of double curved crystals is monopolized by foreign countries and is expensive, the method provided by the embodiment of the present invention is conducive to reducing the price of double curved crystals and expanding their application in the field of X-rays. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments of the present invention or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0036] Figure 1It is a schematic diagram showing the optical path principle and characteristics of a hyperbolic curved crystal;

[0037] Figure 2 It is a schematic diagram of the geometric relationship of the Rowland circle;

[0038] Figure 3 It is a schematic diagram of the geometric relationship between the arc-sagitta radius;

[0039] Figure 4 It is a schematic diagram of the corresponding relationship between the dimensions of the wafer before and after flattening;

[0040] Figure 5 It is a schematic diagram of the number and position of contact points between the punch and the die and the wafer when the wafer is bent using a conventional punch and die;

[0041] Figure 6 1 is a schematic diagram of the steps of a method for preparing a curved crystal according to an embodiment of the present invention;

[0042] Figure 7 is a schematic diagram of the steps of a method for preparing a curved crystal provided by another embodiment of the present invention;

[0043] Figure 8 is a schematic diagram of the steps of a method for preparing a curved crystal provided by another embodiment of the present invention;

[0044] Fig. 9 Schematic diagram of the structure of the concave mold used in the embodiment of the present invention;

[0045] Fig.10 is a schematic diagram of the three-dimensional structure of the pre-compression bending device used in the embodiment of the present invention;

[0046] Fig.11 yes Fig.10 A side structural schematic diagram of the pre-compression bending device shown;

[0047] Fig.12 is along Fig.11 The cross-sectional structure diagram along the AA line;

[0048] Fig.13 yes Fig.12 A is a partial enlarged schematic diagram;

[0049] Fig.14 yes Figure 1 A schematic diagram of the three-dimensional structure of the pre-compression bending device except the bracket and the force-applying unit;

[0050] Fig.15 is a schematic diagram of the structure when the wafer is subjected to step S3 operation by the pre-pressing bending device;

[0051] Fig.16 is a schematic diagram of the bending change of the wafer when performing step S3;

[0052] Fig.17 is a schematic diagram of the structure when the wafer is subjected to step S5 operation by the pre-pressing bending device;

[0053] Fig.18 is a schematic diagram of the bending change of the wafer when performing step S5;

[0054] Fig.19 is a schematic diagram of the structure when the wafer is subjected to step S41 operation by the pre-pressing bending device;

[0055] Fig. 20 is a schematic diagram of the bending change of the wafer when performing step S41;

[0056] Fig.21 is a schematic diagram of the three-dimensional structure of the final pressure bending device used in the embodiment of the present invention;

[0057] Fig. 22 yes Fig.21 A schematic side view of the structure of the final pressure bending device shown;

[0058] Fig.23 is along Fig. 22 The cross-sectional structure diagram of the middle BB line, in which the flexible part is in the initial state;

[0059] Fig.24 After the flexible part is deformed Fig.23 A cross-sectional structural diagram of the final pressure bending device shown.

[0060] Description of reference numerals:

[0061] 100, die; 110, first curved surface; 200, wafer; 300, pre-stress bending device; 310, punch; 311, deformation strip; 312, bracket; 313, force-applying unit; 314, long hole; 320, raised portion; 330, strain gauge; 340, first explosion-proof membrane; 400, final stress bending device; 410, pressure-applying portion; 411, pressure plate; 412, flexible member; 420, second explosion-proof membrane; 430, support frame; 440, driving member; 450, protective film; X', first direction; Y', second direction. DETAILED DESCRIPTION

[0062] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, and should not be construed as limiting the present invention.

[0063] In the description of the present invention, it should be understood that the terms "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship are based on the orientation or position relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0064] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0065] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0066] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments.

[0067] Curved crystals include single curved crystals and double curved crystals (DCC). Single curved crystals include semi-focused (John-Type Curved Crystal) curved crystals and fully focused (Johnson-Type Curved Crystal) curved crystals. Among them, the curved surface of the semi-focused curved crystal is a cylinder tangent to the Rowland circle, and the curved surface of the fully focused curved crystal is a cylinder with a curvature radius consistent with the curvature radius of the Rowland circle.

[0068] The hyperbolic curved crystal is based on the Bragg diffraction principle. Figure 1As shown in the figure, when a hyperbolic curved crystal is used, the X-rays start from the ray source S and converge to point I after being diffracted by the hyperbolic curved crystal. If you want to get X-rays that converge to one point, the crystal must be curved in two directions. Points S and I are located on a Rowland circle with a radius of R. The curvature radius of the crystal in the horizontal direction (meridian direction) is R, and the curvature radius r in the vertical direction (sagittal direction) is 2Rsin2θ, where θ is the diffraction angle.

[0069] The hyperbolic curved crystal must satisfy the Rowland circle geometry. It has a Rowland circle bending radius R in the meridian plane (XY plane) and another bending radius r (2Rsin2θ, where θ is the Bragg diffraction angle) in the sagittal plane (YZ plane). The curve in the XY plane is the Rowland circle, and the curve in the YZ plane is based on the line connecting the light source point and the focusing point as the axis. The whole is a rotation surface with a radius r, with the perpendicular line from the center of the chip to the line connecting the light source point and the focusing point as the axis.

[0070] The characteristics of hyperbolic curved crystals are as follows:

[0071] Place the hyperbolic curved crystal between the ray source and the sample, and satisfy the Rowland circle geometric optical relationship. You can see that the X-rays focused by the hyperbolic curved crystal will converge to one point. If you observe at a defocused position, you can observe an arc. Based on the Bragg diffraction principle, the hyperbolic curved crystal only allows X-rays that meet specific wavelength requirements to pass through, so it has a monochromatic effect. At the same time, it can converge X-rays to one point and increase the intensity of X-rays. These are the two biggest advantages of the hyperbolic curved crystal.

[0072] The above-mentioned curved crystals are generally prepared by first grinding and then bending, or first bending and then grinding, or directly bending. However, the direct bending method is generally only suitable for large-radius, small-sized, and thin wafers. It is not suitable for small-radius, large-sized wafers, and has a low yield rate. Among them, one of the difficulties in processing hyperbolic curved crystals is that the bending radius in the sagittal direction is only a few tens of millimeters, and it is very easy to break during the bending process. Existing literature mostly focuses on the manufacture of large-arc curved crystals or single-direction curved crystals. There are few literatures on the processing of hyperbolic curved crystals, and the specific processing methods have not been published. For existing commercial products, the methods used by XOS to make hyperbolic curved crystals are trade secrets and cannot be obtained.

[0073] To this end, the present invention provides a method for preparing a curved surface crystal, which is applicable to the preparation of various curved surface crystals. Figure 6 As shown, in an embodiment of the present invention, a method for preparing a curved crystal is provided, comprising the following steps:

[0074] S1, providing a concave mold and a wafer to be processed, wherein the concave mold 100 has a first curved surface 110 adapted to the curved surface of the target curved crystal, such as Fig. 9As shown. The target curved surface bent crystal mentioned here refers to the curved surface bent crystal to be obtained by processing through the curved surface bent crystal preparation method provided in this embodiment. The adaptation mentioned here means that the surface radius of the first curved surface 110 is consistent with the surface radius of the target curved surface bent crystal, or is slightly larger than the surface radius of the target curved surface bent crystal, and the size of the first curved surface 110 is generally larger than the size of the surface of the target curved surface bent crystal, which is used to compensate for the curvature deviation caused by the wafer itself and its attachments to be processed.

[0075] Specifically, the target curved surface curved crystal can be a single curved surface curved crystal or a double curved surface curved crystal, which can be flexibly selected according to the use requirements. When the target curved surface curved crystal is a single curved surface curved crystal, the first curved surface 110 is a single curved surface, and when the target curved surface curved crystal is a double curved surface curved crystal, the first curved surface 110 is a double curved surface.

[0076] The die 100 can be made of metal, plastic or other hard materials, and the first curved surface 110 can be made by machining, integral molding or the like. The wafer to be processed generally adopts a flat wafer, and its material can be any single crystal such as mica, silicon, germanium, LiF, graphite, etc., and the specific material can be determined according to the use environment of the target curved surface curved crystal. Specifically, since the target curved surface curved crystal is generally used in the field of X-rays, when determining the material of the above-mentioned wafer to be processed, it is generally necessary to first select the X-ray tube target material used in the X-ray system that applies the target curved surface curved crystal, such as Cu, Rh, Mo, Au, etc. After determining the target material, its Ka line wavelength can be determined, and then the appropriate wafer material can be selected according to the Ka line wavelength. In addition, since the thickness of the above-mentioned wafer to be processed is usually tens of microns, and the X-ray diffraction efficiency is high, the size and material of the wafer to be processed are determined according to the type and design requirements of the target curved surface curved crystal.

[0077] S2. Obtaining the surface parameters of the target curved crystal, the surface parameters including the surface radius and the surface curvature.

[0078] Specifically, the surface parameters mentioned here can be set according to customization needs, or can be inferred based on the target material, wafer material and thickness information. When the surface parameters need to be inferred based on the target material, wafer material and thickness information, the X-ray tube target used in the X-ray system that applies the target curved crystal is generally selected first. After the target material is determined, its Ka line wavelength can be determined. Then, according to the Ka line wavelength, a suitable wafer material is selected, that is, single crystals such as mica, silicon, germanium, LiF, and graphite. At the same time, the crystal plane direction and diffraction angle θ are determined, and then the curvature radius of the target curved crystal is determined based on the diffraction angle θ, and then the curvature of the surface is manually set based on the above-mentioned curvature radius.

[0079] It should be noted that the target curved crystal can be a single curved crystal or a double curved crystal, and the single curved crystal has only one curved radius and one curved curvature, namely, the Rowland circle radius R on the meridian plane and the curved curvature on the meridian plane. The hyperbolic curved crystal has two surface radii and two surface curvatures. The two surface radii are the Rowland circle radius R on the meridian plane and the radius r on the sagittal plane. The two surface curvatures are the surface curvature on the meridian plane. and the curvature of the surface on the sagittal plane Therefore, when the target curved crystal is a single curved crystal, the surface radius in the above surface parameters is the radius R of the Rowland circle on the meridian plane, and the surface curvature is the curvature of the surface on the meridian plane. When the target curved crystal is a hyperbolic curved crystal, the surface radius in the above surface parameters includes the Rowland circle radius R on the meridian plane and the radius r on the sagittal plane; the surface curvature includes the surface curvature on the meridian plane and the curvature of the surface on the sagittal plane

[0080] The above-mentioned curvature is generally selected manually based on the material and thickness of the wafer according to experience. Generally, the smaller the curvature radius of the target curved crystal is, the smaller the wafer size should be, that is, the smaller the curvature of the curvature is, otherwise it is easy to break. The determination of the curvature radius generally needs to be based on some formulas. For ease of understanding, the target curved crystal is a hyperbolic curved crystal as an example to illustrate how to calculate its curvature radius.

[0081] (1) Calculate the Bragg incident angle θ

[0082] The target material is Rh target, and its Ka line energy is: E = 20.22keV;

[0083] The single crystal is selected as mica, and its interplanar spacing is: in

[0084] According to the energy wavelength formula: E = hc / λ;

[0085] Bragg formula: nλ=2dsinθ, take n=1;

[0086] The incident angle θ can be obtained, θ=arcsin(λ / 2d)=5.2977°.

[0087] (2) Calculate the radius R of the Rowland circle, i.e. the radius in the meridian direction

[0088] like Figure 2 As shown, the X-ray source position S, the light receiving point D of the curved crystal and the corresponding node E of the Rowland circle form △SED. Specifically, △SED is a right triangle, and SD = ED × sinθ = 2Rsinθ; that is, F = 2Rsinθ.

[0089] Because of the symmetry relationship SD = DP, that is, the front and rear focal lengths are equal. According to the above formula, the focal length F = 249.73 mm is artificially selected; the Rowland circle R = F / (2sinθ) = 1352.368 mm can be obtained.

[0090] (3) Calculate the sagittal radius r

[0091] like Figure 2 As shown, the X-ray source position S, the light receiving point D of the curved crystal and the center G of the sagittal plane form △SGD. Specifically, △SGD is a right triangle, and r = SD × sinθ = 2Rsin2θ, as Figure 3 That is, in the sagittal direction, r = 2Rsin2θ = 23.058 mm.

[0092] It is understandable that when other target materials are used, the Ka line energy in the above calculation changes accordingly, which in turn causes the calculation results of the above parameters to change. This is a prior art and will not be described in detail here. At the same time, when the curved surface bent crystal is a single curved surface bent crystal, its calculation method is similar to the above method, but there is no need to calculate the sagittal radius r.

[0093] S3, applying a first pressure to the two first edges extending along the first direction X' of the wafer, so that the first edges fit the first curved surface, until the first edges form a curved surface structure that matches the shape of the corresponding area in the first curved surface. There are multiple contact points distributed along the meridian direction between the first pressure and the wafer, and the first direction X' is a direction corresponding to the meridian direction of the target curved surface curved crystal. The first direction X' corresponding to the meridian direction of the target curved surface curved crystal here refers to the straight line direction in which the extension direction in the planar wafer is substantially consistent with the meridian direction of the target curved surface curved crystal in the initial state.

[0094] Specifically, Fig.16 As shown, this step can be implemented with the aid of one or more sheet-shaped or block-shaped punches located on the side of the wafer away from the die. Each punch can be in point contact or surface contact with the wafer 200. When each punch is required to be in surface contact with the wafer 200, a flexible part capable of deformation can be used to achieve this, so that the contact surface between the punch and the wafer 200 can be deformed, and then the side of the punch used to contact the wafer 200 can always fit the wafer 200 during the deformation of the curved surface of the wafer 200. This step can be performed slowly and continuously over a period of time, or pressure can be applied repeatedly and intermittently over a period of time, which can be determined according to the condition of the wafer 200 during the processing (such as the magnitude of the internal strain).

[0095] S4, such as Fig. 20As shown, a second pressure is applied to the wafer so that a side of the wafer close to the first curved surface is closely fitted to the first curved surface until the wafer forms a target curved surface structure that matches the first curved surface.

[0096] Specifically, this step can be implemented with the help of a convex mold in the prior art, or other convex molds that can achieve the above functions can be designed by yourself. The above pressure application process can be carried out slowly and continuously over a period of time, or repeatedly and intermittently over a period of time, and can be completed with the help of a set of molds or with the help of multiple molds, depending on the condition of the wafer during the processing (such as the size of the internal strain).

[0097] The working principle of the curved crystal preparation method provided by the embodiment of the present invention is as follows:

[0098] Traditional curved crystals are formed by pressing the concave and convex dies set up above and below. Figure 5 As shown, the male mold has only one contact point with the wafer 200, and the female mold 100 has four contact points with the wafer 200. Due to the stress concentration problem, the four contact points between the female mold 100 and the wafer 200 can easily cause the wafer 200 to break.

[0099] To solve the above problems, the inventors further studied the method for preparing a curved crystal provided by an embodiment of the present invention, and found that when the target curved crystal is a single-curved crystal, the target curved crystal only has a bending radius R in the meridian direction. When the target curved crystal is a double-curved crystal, although it has both a bending radius R in the meridian direction and a bending radius r in the sagittal direction, the bending radius R in the meridian direction is generally larger and the bending stress is small, while the bending radius r in the sagittal plane is 2Rsin2θ, sin2θ<<1, that is, the bending radius in the sagittal plane is much smaller, and it is very easy to break during the bending process of a single crystal thin slice. For this reason, the method for preparing a curved crystal provided by an embodiment of the present invention is proposed.

[0100] When the wafer 200 is subjected to a bending operation, a first pressure is first applied to two first edges of the wafer 200 extending along the first direction X', so that the first edges are fitted with the first curved surface 110, until the first edges form a curved surface structure that matches the shape of the corresponding area in the first curved surface 110. At this time, other areas of the wafer 200 will also bend accordingly, forming a curved crystal shape as a whole, such as Fig.16 During the above operation, there are multiple contact points between the first pressure and the wafer 200 distributed along the meridian direction, so that the point pressure of the punch on the wafer 200 is converted into a line pressure formed by multiple action points, thereby reducing the stress on the local part of the wafer 200 and reducing the internal strain of the wafer 200.

[0101] However, after the above operation, the central area of ​​the chip 200 may not be in contact with the first curved surface 110. Then, the chip 200 is pressurized as a whole through an ordinary punch or other device so that the central area, center line, etc. of the chip 200 can also be tightly fitted with the first curved surface 110, that is, the side of the chip 200 that is used to connect with the first curved surface 110 is in contact with the first curved surface 110, until the chip 200 forms a curved surface structure that matches the first curved surface 110.

[0102] In summary, the method for preparing a curved surface curved crystal provided by the embodiment of the present invention changes the inherent method of directly applying pressure to the wafer 200 through a convex mold and a concave mold with a fixed shape in the traditional technology to achieve the preparation of the target curved surface curved crystal, and provides a new method for preparing a curved surface curved crystal. During preparation, a first pressure is first applied to two first edges of the wafer 200 extending along the first direction X', so that the corresponding edges (i.e., the first edges) of the wafer 200 are fitted with the first curved surface 110 to obtain a single curved surface curved crystal, and then the wafer 200 is pressed as a whole to obtain the final target curved surface curved crystal. There are multiple contact points distributed along the meridian direction between the first pressure and the wafer 200, so that the point pressure applied by the convex mold on the wafer 200 is converted into a linear pressure formed by multiple action points, which can effectively reduce the stress on the local part of the wafer 200 during the preparation of the single curved surface curved crystal, thereby reducing the internal strain of the wafer 200, reducing the risk of multiple contact points of the wafer 200 and the concave mold 100 being broken during the processing, and improving the yield rate of the target curved surface curved crystal. At the same time, the target curved surface bent crystal is completed by applying pressure twice, which can further reduce the internal strain of the chip 200 during the processing, reduce the risk of breakage at multiple contact points between the chip 200 and the die 100 during the processing, and improve the yield of the target curved surface bent crystal.

[0103] The method for preparing curved crystals provided by the embodiment of the present invention can realize the preparation of single curved crystals, double curved crystals, etc., and is suitable for the preparation of curved crystals with small curvatures. The finished products have a high yield and can be widely used in the fields of X-ray diffraction (XRD), X-ray reflectometry (XRR), microfocus fluorescence analysis (XRF), total reflection fluorescence analysis (TXRF), etc. In addition, since the current preparation technology of double curved crystals is monopolized by foreign countries and is expensive, the method provided by the embodiment of the present invention is conducive to reducing the price of double curved crystals and expanding their application in the field of X-rays.

[0104] The above step S4 can be implemented by one mold in one operation, or by multiple molds in multiple operations. When multiple molds are used in multiple operations, the risk of chip 200 being broken during the processing can be further reduced.

[0105] like Figure 7 As shown, in an optional embodiment, the above step S4 includes the following steps:

[0106] S41, applying a third pressure distributed at intervals to the entire force-bearing surface of the wafer until the force-bearing area of ​​the wafer forms a curved surface structure that matches the shape of the corresponding area of ​​the first curved surface.

[0107] Specifically, in this step, the contact area between a single third pressure and the wafer is smaller than the area of ​​the force-bearing surface of the wafer, and the sum of the contact areas between all third pressures and the wafer is smaller than the area of ​​the force-bearing surface of the wafer. This step can be achieved with the aid of multiple sheet-shaped or block-shaped punches located on the side of the wafer away from the die. The punch may have a continuous flexible part extending in the meridian direction, or a flexible part distributed at intervals along the meridian direction, or a continuous or spaced flexible part extending in a direction perpendicular to the meridian direction, or a flexible part arranged in other ways, so that when the third pressure is applied to the wafer, it can always fit the wafer; other structures may also be used, such as a convex surface structure of the ordinary punch type, as long as the above functions can be achieved, and no unique limitation is made here. This step may be performed slowly and continuously over a period of time, or pressure may be applied repeatedly and intermittently over a period of time, depending on the condition of the wafer during processing (such as the magnitude of internal strain).

[0108] S42, applying a fourth pressure to the entire force-bearing surface of the wafer until the entire force-bearing surface of the wafer is in contact with the first curved surface to form a target curved surface structure. The contact area of ​​the fourth pressure and the wafer is greater than or equal to the area of ​​the force-bearing surface of the wafer.

[0109] Specifically, this step can be implemented with the help of a convex mold in the prior art, or other convex molds that can achieve the above function can be designed by yourself. The above pressure application process can be carried out slowly and continuously over a period of time, or it can be repeatedly and intermittently over a period of time, which can be determined according to the condition of the wafer during the processing (such as the size of the internal strain).

[0110] By adopting the steps provided in this embodiment, step S4 is divided into two steps for implementation, and the third pressure interval distribution setting can effectively reduce the internal strain of the wafer during the operation of each step, thereby effectively reducing the risk of wafer breakage.

[0111] The above steps S3 and S41 can be implemented in a variety of ways. For ease of operation, in an optional embodiment, the above steps S3 and S41 are implemented by a pre-pressing bending device, such as Fig.15 , Fig.16 , Fig.19 and Fig. 20 In this way, the two adjacent steps in the above operation sequence can be implemented by the same device, which can improve the processing efficiency.

[0112] like Figures 10 to 14 As shown, the pre-stressing bending device 300 includes a die 100 and a punch 310, the punch 310 has a plurality of deformation strips 311 spaced apart along the first direction, the deformation strips 311 are located on the side of the chip 200 away from the die 100, and can be deformed under the action of the first pressure and the third pressure to change from a first state adapted to the initial shape of the chip 200 to a second state adapted to the shape of the corresponding area of ​​the first curved surface 110.

[0113] Since the target curved crystal can be a single-curved crystal or a hyperbolic single crystal, the first curved surface 110 can be a single-curved surface or a hyperbolic surface. When the first curved surface 110 is a hyperbolic surface, the first state and the second state of the second curved surface are generally also hyperbolic surfaces. At this time, different areas of the second curved surface have different degrees of curvature. At this time, if the side of the punch 310 used to contact the chip 200 adopts an integrated structure, it is more difficult to deform into a curved surface that matches the first curved surface 110.

[0114] To this end, the inventor has developed a male mold 310 provided in this embodiment, and the male mold 310 has a plurality of deformation strips 311 spaced apart and distributed along the first direction. Specifically, the deformation strip 311 in this embodiment is a strip structure with a certain elasticity and can be bent, and can be a metal strip, a plastic strip, a rubber strip, etc., and can be an integrated structure, such as a metal strip, a plastic strip, a rubber strip, etc., or a multi-layer structure, such as a stacked metal strip and a rubber strip, a plastic strip and a rubber strip, etc., and can be flexibly selected according to the use needs. In addition, the deformation strip 311 in this embodiment can be deformed under the action of the first pressure and the third pressure, so as to change from the first state adapted to the initial shape of the wafer 200 to the second state adapted to the shape of the corresponding area of ​​the first curved surface 110, thereby applying pressure to the wafer 200. In the above-mentioned pressure application process, the deformation strip 311 can always be closely attached to the wafer 200 to achieve surface contact with the wafer 200, and the above-mentioned process can be carried out slowly to improve the stress distribution of the wafer 200 and reduce the internal strain of the wafer 200 to a smaller degree, thereby effectively reducing the risk of chipping of the wafer 200 during processing. At the same time, the provision of multiple deformation strips 311 can realize the control of the bending radius of the wafer 200 in two directions, and can not only cooperate with the concave mold 100 to prepare regular single-curved surface curved crystals and double-curved surface curved crystals, but also prepare curved surface curved crystals with asymmetric arc surfaces.

[0115] The pre-stressing bending device 300 provided in this embodiment utilizes deformation adaptive technology, which effectively increases the contact area between the punch 310 and the chip 200, reduces the risk of stress concentration in the chip 200 during processing, and can effectively improve the yield rate. It is suitable for the preparation of most curved crystals, especially the preparation of hyperbolic crystals with a small bending radius, and is simple to adjust and easy to operate.

[0116] like Fig.12 and Fig.13 As shown, in an optional embodiment, the male mold 310 includes a bracket 312, a deformation bar 311 and a force-applying module corresponding to the deformation bar 311. The force-applying module is mounted on the bracket 312 and is located on the side of the deformation bar 311 away from the female mold 100, and is used to apply reciprocating pressure to the corresponding deformation bar 311. Each force-applying module includes a plurality of force-applying units 313 arranged at intervals along the second direction Y'. The two ends of the deformation bar 311 in the second direction Y' are respectively connected to the female mold 100 or the bracket 312 in a sliding manner along the second direction Y'. The second direction Y' is a direction corresponding to the sagittal direction of the target curved surface bent crystal. The second direction Y' mentioned here as corresponding to the sagittal direction of the target curved surface bent crystal refers to a straight line direction in which the extension direction in the planar wafer is substantially consistent with the sagittal direction of the target curved surface bent crystal in the initial state.

[0117] Specifically, the structures of the force-applying monomers 313 may be the same or different. With this structure, when implementing the operation of step S3, the force-applying monomers 313 corresponding to the two first edge positions of the wafer 200 extending along the first direction X' are selected, and the amount of pressing on the wafer 200 is adjusted. With the adjustment of the pre-pressing amount, the two first edges of the wafer 200 will gradually fit with the first curved surface 110, and during the whole process, multiple pressure-applying parts 410 are in contact with the wafer 200, and the contact stress is small. At the same time, the use of this structure also helps to smoothly proceed with step S41. Specifically, when performing step S41, the amount of pressure applied by all force-applying units 313 on the chip 200 is adjusted so that different areas of the chip 200 can be fitted with the first curved surface 110. Since the force-applying units 313 are independent of each other, different areas of the deformation strip 311 can be deformed to different degrees as needed, so that the chip 200 can be adapted to first curved surfaces 110 of different shapes. Compared with each force-applying module using a single force-applying unit 313, the possibility of the deformation member realizing complex deformation can be further improved to meet the preparation needs of bent crystals with different curved surfaces.

[0118] In an optional embodiment, the force-applying unit 313 includes a screw-connected member threadedly connected to the bracket 312. Specifically, the screw-connected member can be a screw, a screw rod, or a combination of a screw, a screw rod, etc. and other components, which can be flexibly selected according to the use requirements and are not limited here. The force-applying unit 313 adopts the structure provided by this embodiment, which is simple in structure, easy to adjust, and low in cost.

[0119] In a specific embodiment, the screw connection member is a fine-thread screw or a micrometer head. By adjusting its depth, the curvature of the deformation strip 311 can be changed. A hyperboloid can be profiled by multiple screw connections and multiple deformation strips 311.

[0120] In order to further reduce the risk of chip 200 being broken when the pre-pressing bending device 300 provided in the above embodiments is used for operation, Fig.13 As shown, in an optional embodiment, the pre-stressing and bending device 300 also includes a first explosion-proof membrane 340, which is used to be attached to the back side of the chip 200 to provide support for the chip 200, improve the toughness of the chip 200, and reduce the risk of local breakage thereof.

[0121] Specifically, the wafer 200 has a reflective surface and a surface opposite to the reflective surface. Generally, the reflective surface is called the front surface, and the surface opposite to the reflective surface is called the back surface. Fig.13 The upper surface of the middle wafer 200 is a reflective surface, and the first explosion-proof film 340 is attached to the lower surface of the wafer 200, that is, the side of the wafer 200 that contacts the first curved surface 110. The first explosion-proof film 340 in this embodiment can be a strong and tough film made of a polymer material, with a surface coated with glue, and attached to the wafer 200.

[0122] like Fig.13 As shown, in an optional embodiment, the pre-compression bending device 300 further includes a strain gauge 330. The strain gauge 330 is located between the die 100 and the punch 310, and is used to be attached to the upper surface or the lower surface of the wafer 200 and monitor the strain of the wafer 200. When in use, the strain gauge 330 can be attached to the wafer 200 first, and then the wafer 200 is placed on the die 100. The strain gauge 330 in this embodiment can be a wireless strain gauge or a wired strain gauge. When the strain gauge 330 adopts a wired structure, after the chip 200 is placed on the die 100, the data line connected to the strain gauge 330 needs to be connected to an external data processing device (such as a computer) through the gap between the deformation bars 311; when the strain gauge 330 adopts a wireless structure, the strain gauge 330 is connected to the external data processing device (such as a computer) through wireless transmission. This connection is convenient and there is no need to worry about the data line being adversely affected during the bending process of the chip 200, or the presence of the data line causing adverse effects on the bending operation of the chip 200.

[0123] It should be noted that when the pre-stressed bending device 300 is provided with both the first explosion-proof membrane 340 and the strain gauge 330, the two need to be separately provided on both sides of the wafer 200. At this time, since the first explosion-proof membrane 340 is generally attached to the back of the wafer 200, the strain gauge 330 is attached to the reflective surface of the wafer 200. When the curved surface bending crystal preparation device is only provided with the strain gauge 330, in order to avoid the strain gauge 330 from damaging the reflective surface of the wafer 200, the strain gauge 330 is generally attached to the back of the wafer 200. Since the strain gauge 330 is attached to the reflective surface, it needs to be removed after use, and the removal will affect the normal use of the wafer 200. Therefore, this solution is only suitable for studying the pressure applied to the wafer 200 at each stage in the curved surface wafer preparation process, and is not suitable for use when preparing the target curved surface.

[0124] With this structure, when processing the wafer to be processed, the strain of the wafer 200 can be measured in real time through the strain gauge 330, and the internal stress of the wafer 200 can be inferred with the help of an external data processing device, so that the operator can adjust the pressure applied to the deformable part according to the monitoring result to prevent the phenomenon that the internal stress of the wafer 200 exceeds the yield strength and breaks due to excessive pressure, thereby improving the yield rate. After the bending process is determined, the strain gauge 330 can be cancelled. The pre-stressing bending device 300 provided in this embodiment adopts stress-strain adaptive technology and combines stress analysis technology to ensure that the internal stress of the wafer 200 is monitored during the measurement process. When in use, the pre-stressing amount applied to the deformable part can be continuously adjusted according to the monitoring results to achieve pre-stressing of the wafer 200, which can greatly reduce the probability of curved surface wafers breaking during the bending process.

[0125] like Fig.13 As shown, in an optional embodiment, the strain gauge 330 is attached to the side of the chip 200 away from the first curved surface 110 to avoid the strain gauge 330 being attached to the side of the chip 200 that contacts the first curved surface 110 and causing adverse effects on the first curved surface 110 .

[0126] On the basis of the above embodiments, in order to further improve the stability of the pressure applied by the force-applying member to the deformable member, as Fig.13 As shown, in an optional embodiment, the screw connection includes a shoulder screw threadedly connected to the bracket 312, and a constant force elastic member sleeved on one end of the shoulder screw near the die 100. Specifically, the constant force elastic member is sleeved on the shoulder screw, the two are concentric, and the shoulder on the shoulder screw can block the constant force elastic member from moving upward, so that when the shoulder screw is rotated downward, the constant force elastic member is squeezed, and the other end thereof contacts the deformable member and pushes it to bulge downward. Through the shoulder screw, not only the contouring of the curved surface is achieved, but also due to the action of the constant force elastic member, the wafer 200 is always in a stressed state, which is conducive to its continuous deformation until it fits with the first curved surface 110.

[0127] There are many ways to slide the deformation bar 311 and its supporting component (die 100 or bracket 312), such as providing a slide groove on the deformation bar 311, and providing a slide rail or slider for sliding cooperation with it on its supporting component; or providing a slide rail or slider on the deformation bar 311, and providing a slide groove for sliding cooperation with it on its supporting component. Of course, other forms can also be used.

[0128] like Fig.12 and Fig.14 As shown, in an optional embodiment, the female mold 100 or the bracket 312 is provided with a plurality of protrusions 320 corresponding to the plurality of deformation strips 311 on both sides of the second direction Y'. Both ends of each deformation strip 311 are provided with a long hole 314 extending along the second direction Y'. The long hole 314 is used for the corresponding protrusion 320 to pass through and slide, so as to realize the sliding connection between the deformation strip 311 and the female mold 100 or the bracket 312.

[0129] In the initial state, the deformation strip 311 is in a straight state or an initial bending state. At this time, the horizontal spacing of the long strip holes 314 at both ends of the same deformation strip 311 is relatively long, and the protrusion 320 is generally located in the first area of ​​the long strip holes 314. The first area here refers to the half area of ​​the long strip holes 314 close to the center of the deformation strip 311. When the deformation strip 311 is subjected to pressure, its bending degree gradually increases, and then the horizontal spacing of the long strip holes 314 at both ends of the same deformation strip 311 gradually shortens. During this period, the protrusion 320 is always located in the corresponding long strip holes 314 to limit the expansion and contraction of the two ends of the deformation strip 311 in the second direction Y'.

[0130] The structure provided in this embodiment not only realizes the sliding connection between the deformation bar 311 and the concave mold 100 or the bracket 312, but also makes the deformation bar 311 easy to install.

[0131] In the above embodiment, the protrusion 320 can be integrally formed on the die 100 or the bracket 312, or can be detachably fixed to the die 100 or the bracket 312. When the protrusion 320 is integrally formed on the die 100 or the bracket 312, the structure is stable and easy to assemble; when the protrusion 320 is detachably mounted on the die 100 or the bracket 312, it is easy to maintain and replace.

[0132] The above step S42 can be implemented in a variety of ways. In order to reduce the risk of chip breakage during operation, in an optional embodiment, the above step S42 can be implemented by a final pressure bending device.

[0133] like Figure 21 to Figure 24As shown, the final pressure bending device 400 includes a concave mold 100, a pressure component, a second explosion-proof film 420 and a protective film 450. The pressure component has a pressure portion 410. The pressure portion 410 is located on the side of the wafer 200 away from the first curved surface 110. The pressure portion 410 is used to apply pressure toward the first curved surface 110 to the wafer 200, so that the surface of the wafer 200 close to the first curved surface 110 is closely attached to the first curved surface 110. The second explosion-proof film 420 is used to be attached to the back of the wafer 200, and the protective film 450 is used to be attached to the reflective surface of the wafer 200.

[0134] The pressure-applying assembly in this embodiment can be a manual assembly, which applies pressure to the wafer 200 under the drive of a hand or other external object when in use; or it can be an electric assembly, such as a pressure block having a driving member 440 such as a cylinder or a hydraulic cylinder, which automatically applies pressure to the wafer 200 through an electric power system, a pneumatic system, etc. When in use. Among them, the side of the pressure-applying part 410 used to contact the wafer 200 can have a flexible layer, or the shape is adapted to the first curved surface 110, so that when the pressure is driven to clamp the wafer 200 with the first curved surface 110, the side of the wafer 200 close to the first curved surface 110 can be closely attached to the first curved surface 110, thereby making the curved surface of the pressed wafer 200 adapted to the first curved surface 110. The adaptation mentioned here means that the curved surface shape and radius of the wafer 200 are consistent with or approximately equal to the curved surface shape and radius of the first curved surface 110.

[0135] The working principle of the final pressure bending device 400 used in this embodiment is as follows:

[0136] When in use, the second explosion-proof film 420 is attached to the back side of the chip 200 to be processed, and the protective film 450 is attached to the reflective surface of the chip 200 to be processed. Then, the chip 200 to be processed is placed between the first curved surface 110 and the pressure-applying part 410, and the pressure-applying part 410 is controlled to apply pressure to the chip 200 toward the first curved surface 110, so that the surface of the chip 200 close to the first curved surface 110 is tightly fitted with the first curved surface 110 until the chip 200 is shaped.

[0137] During this period, since the second explosion-proof film 420 is attached to the wafer 200, the risk of the wafer 200 being broken during the pressing process can be effectively reduced. At the same time, in order to further reduce the risk of the wafer 200 being broken during the above process, the wafer to be processed used in this embodiment can be a wafer 200 that has been pressed and deformed by other bending devices. In this way, the wafer 200 placed between the first curved surface 110 and the pressure-applying portion 410 itself has a curved surface shape equivalent to the first curved surface 110, and only a small amount of deformation is required to form a shape that matches the first curved surface 110, which can further reduce the risk of its breaking. In this embodiment, the protective film is without glue or is a bottom glue film that does not remain after being torn off. When the wafer 200 is prepared, the protective film 450 is torn off, which can effectively protect the reflective surface of the wafer 200 from scratches.

[0138] To further reduce the risk of chip 200 breaking when the pressure applying portion 410 applies pressure to the chip 200, please refer to Fig.23 As shown, in an optional embodiment, the pressure applying portion 410 includes a pressure plate 411 and a flexible member 412 . The flexible member 412 is installed on a side of the pressure plate 411 opposite to the first curved surface 110 and is used to contact the wafer 200 .

[0139] In an optional embodiment, the flexible member 412 is a soft rubber member. Fig.23 As shown, in the initial state, the projection area of ​​the flexible member 412 on the first curved surface 110 is smaller than the projection area of ​​the pressing plate 411 on the first curved surface 110; Fig.24 As shown, under pressure, the flexible member 412 can fill the entire space between the pressure plate 411 and the first curved surface 110 .

[0140] In this embodiment, the soft rubber part can be made of silicone with good fluidity, or an airbag filled with water or gas. The soft rubber part has a good filling effect. During use, when the pressure-applying part 410 receives pressure, the pressure plate 411 will move toward the first curved surface 110. At the same time, the soft rubber part will gradually contact the wafer 200 and be squeezed and deformed. As the soft rubber part is continuously deformed by force, it gradually fills the entire space surrounded by the pressure plate 411 and the wafer 200, and applies uniform pressure to the wafer 200, so that the wafer 200 is completely fitted with the first curved surface 110. With this structure, different areas of the wafer 200 are subjected to uniform force, which can reduce the risk of it breaking.

[0141] The above pressure-applying components have various implementation forms, please refer to Figure 21 to Figure 24As shown, in an optional embodiment, the pressure assembly includes a support frame 430, a driving member 440 and a pressure portion 410. The driving member 440 is mounted on the support frame 430 and is located on the side of the pressure portion 410 away from the first curved surface 110. The driving member 440 has a telescopic function or can move relative to the support frame 430, and is used to apply a thrust toward the first curved surface 110 to the pressure portion 410. In this embodiment, the support frame 430 is used to support the driving member 440, and the driving member 440 is limited to the side of the pressure portion 410 away from the first curved surface 110. Its shape can be flexibly set according to the needs of use, such as it can adopt an L-shaped structure, a U-shaped structure, etc., which is not limited here. The driving member 440 can be a manual member, which is driven by hand or other external objects when in use, or an electric member, such as a cylinder, an electric cylinder, a hydraulic cylinder, etc. In addition, the driving member 440 can be connected to the pressure-applying part 410 or not. When the driving member 440 is connected to the pressure-applying part 410, it can not only apply a thrust toward the first curved surface 110 to the pressure-applying part 410, but also apply a pulling force on the first curved surface 110 to the pressure-applying part 410. The specific selection can be flexibly made according to the needs of use, and no sole limitation is made here.

[0142] By adopting the structure provided in this embodiment, the overall structure of the pressure-applying assembly is simple, and it is convenient to apply pressure to the pressure-applying part 410 , thereby facilitating smooth processing of the wafer 200 .

[0143] Since the curvature of single-curved and double-curved crystals is different, in order to further reduce the risk of chip breakage during the preparation process when the target curved crystal is a double-curved crystal, such as Figure 8 As shown, in an optional embodiment, the target curved surface bent crystal is a double curved surface bent crystal, and the curved surface bent crystal preparation method further includes the following steps located between step S3 and step S4:

[0144] S5, applying a fifth pressure to two second edges of the wafer that are arranged opposite to each other in the first direction, so that the second edges fit the first curved surface, until the second edges form a curved surface structure that matches the shape of the corresponding area in the first curved surface, wherein the fifth pressure has a plurality of contact points with the wafer distributed along the second direction Y'.

[0145] Specifically, this step can be achieved by the above-mentioned pre-compression bending device (such as Fig.17 and Fig.18As shown in the figure), it can also be achieved with the help of one or more other sheet or block-shaped punches located on the side of the wafer away from the die. Each punch can be in point contact or surface contact with the wafer. When each punch needs to be in surface contact with the wafer, a flexible part that can be deformed can be used to achieve it, so that the contact surface between the punch and the wafer can be deformed, and then the side of the punch that is used to contact the wafer can always fit the wafer during the deformation of the curved surface of the wafer. This step can be carried out slowly and continuously over a period of time, or it can be repeatedly and intermittently pressed over a period of time, which can be determined according to the condition of the wafer during the processing (such as the size of the internal strain).

[0146] The method for preparing a curved crystal provided in this embodiment is suitable for preparing a double-curved crystal, such as Figures 15 to 20 As shown, during preparation, step S3 can be performed first to achieve unilateral pre-stressing in the meridian direction, and then step S5 can be performed to achieve unilateral pre-stressing in the sagittal direction. After the above two steps are completed, the center position of the chip often cannot contact the lowest position of the first curved surface. Finally, step S4 is performed to achieve comprehensive pre-stressing, which can effectively reduce the deformation of the chip in step S4, thereby reducing the risk of chip breakage during step S4, thereby improving the product yield.

[0147] The wafer to be processed can be purchased or made by oneself. When making it by oneself, it can be prepared in the following manner. Exemplarily, the above-mentioned provision of the concave mold and the wafer to be processed includes the following steps:

[0148] S11, providing a concave mold and a wafer to be cut.

[0149] Specifically, the wafer to be cut is generally a planar wafer having a size larger than the wafer to be processed.

[0150] S12, obtaining the arc lengths of the sides and the center line length of the target curved crystal.

[0151] Specifically, the target curved crystal is generally a regular shape. After the radius and curvature of the target curved crystal are determined, the arc length and center line length of each side of the target curved crystal can be calculated, and can also be set according to customized requirements. Figure 4 As shown, the arc lengths of the two long sides a set opposite to each other in the target curved crystal are equal, the arc lengths of the two short sides b are equal, and there are two center lines (a' and b'). The arc lengths of the above sides and the lengths of the center line can be calculated by the radius and curvature of the curved surface and known techniques, which will not be elaborated here.

[0152] S13, obtaining processing parameters of the flat wafer after flattening according to the arc lengths of the sides and the center line length of the target curved wafer, the processing parameters including the arc lengths of the sides and the center line length of the flat wafer.

[0153] Specifically, Figure 4 As shown, the arc lengths of the sides of the target curved crystal are the arc lengths of the sides of the planar wafer, and the centerline length of the target curved crystal is the centerline length of the planar wafer.

[0154] S14, cutting the wafer to be cut according to the processing parameters to obtain the wafer to be processed.

[0155] Since the target curved crystal is a curved structure, and the wafer used in processing is generally a flat wafer, in order to improve the yield of the curved crystal, in the actual processing process, the curved surface of the target curved crystal is flattened (which can be done through simulation software) to obtain the corresponding wafer processing parameters. The processing parameters include the curvature of each side of the wafer after flattening, the arc length, etc. Figure 4 As shown, in some embodiments, after the wafer is flattened, it can be seen that the wafer is actually a structure with concave sides and convex top and bottom. In other embodiments, the wafer can also have other shapes after being flattened, which is not limited here.

[0156] Compared with the wafer to be processed using a rectangular structure, this structure can make the edge shape of the wafer to be processed more closely match the side length shape of the target curved crystal, thereby effectively reducing the risk of wafer breakage during subsequent processing.

[0157] In some other embodiments, the method for preparing a curved crystal further comprises the following steps:

[0158] S6. Provide a substrate.

[0159] The substrate may be made of plastic material, metal material, etc., and generally has a supporting surface matched with the first curved surface, and is used to support the processed target curved surface bent crystal.

[0160] S7, bonding the wafer formed with the target curved surface structure to the substrate by using glue having a coefficient of expansion close to that of the wafer.

[0161] By fixing the target curved crystal and the substrate with a close expansion coefficient glue, the risk of cracking of the target curved crystal due to temperature changes during use can be effectively reduced. During use, the target curved crystal can be moved and adjusted in position through the substrate, which can effectively reduce the risk of directly touching the wafer and affecting the wafer's service life and performance.

[0162] In some other embodiments, the method for preparing a curved wafer further includes the following steps after the wafer forms a target curved surface structure that matches the first curved surface (i.e., step S4):

[0163] S8. Detect whether the target curved surface structure is consistent with the curved surface of the target curved surface bent crystal.

[0164] This step can be tested by using a concave mold and a convex mold with a curved surface structure consistent with the curved surface of the target curved crystal. During the test, the wafer generated after step S4 is placed between the concave mold and the convex mold, and pressure is applied to the mold located above so that it is as close as possible to the mold located below under the action of gravity or gravity and external pressure. When it moves to the lowest position, check whether the distance between the two molds is the thickness of the wafer. If not, and the difference is greater than the error value, it is proved that the target curved surface structure formed by the wafer formed through the above steps is unqualified. If yes, or there is a difference but it is within the error value, it is proved that the target curved surface structure formed by the wafer formed through the above steps is qualified.

[0165] Step S8 can be used to verify whether the curved surface structure of the product meets the requirements, so that problems can be discovered in time when the product is unqualified, and unreasonable places in the above steps can be adjusted to ultimately ensure the qualified rate of the finished product.

[0166] It should be noted that, when step S6 and step S7 exist, step S8 is generally performed before step S6 and step S7.

[0167] In a specific embodiment, the target curved crystal is a hyperbolic curved crystal, and the curved crystal preparation method includes steps S1, S2, S3, S4 and S5, wherein step S4 includes steps S41 and S42, and the above steps S3, S41 and S5 are all implemented by a pre-pressing bending device as shown in the figure, and the above step S4 is implemented by a final pressing bending device.

[0168] When preparing hyperbolic curved crystals, Fig.15 As shown in the figure, the amount of pressure applied by the force-applying monomer located at the first edge of the wafer (i.e., the force-applying monomer framed by the dotted line in the figure) on the deformation strip is increased, and the first edge of the wafer (i.e., the edge extending along the meridian direction) is pre-pressed until the first edge of the wafer is in contact with the first curved surface and the two are in line contact, as shown in the figure. Fig.16 As shown; then Fig.17 As shown in the figure, the pressing amount of the force-applying monomer located at the second edge of the wafer (i.e., the force-applying monomer framed by the dotted line in the figure) on the deformation strip is increased to pre-press the second edge of the wafer until all four edges of the wafer are in contact with the first curved surface and the two are in line contact, as shown in the figure. Fig.18 As shown, the final increase is as Fig.19 The remaining force-applying monomers (i.e., the force-applying monomers framed by the dotted lines in the figure) press the deformation strips so that they pre-press the remaining area of ​​the wafer until the center line and the center area of ​​the wafer are in contact with the first curved surface. Fig. 20 shown.

[0169] Also, since the pre-pressing and bending device uses deformation strips arranged at intervals, although it can adapt well to the first curved surface shape in the above process, there is also a risk of wavy texture appearing on the chip. Therefore, after the above operation, the mold is replaced with a final pressing and bending device, and the entire surface of the chip is pre-pressed again until the chip is shaped to form the final target curved surface.

[0170] The above description is only a preferred embodiment of the present invention, and only specifically describes the technical principle of the present invention. These descriptions are only for explaining the principle of the present invention and cannot be interpreted as limiting the scope of protection of the present invention in any way. Based on the explanation here, any modification, equivalent substitution and improvement made within the spirit and principle of the present invention, and other specific embodiments of the present invention that can be associated with by technicians in this field without creative labor, should be included in the scope of protection of the present invention.

Claims

1. A method for preparing a curved crystal, characterized in that: The following steps are involved: Providing a concave mold and a wafer to be processed, wherein the concave mold has a first curved surface adapted to the curved surface of a target curved wafer; Acquire the surface parameters of the target curved crystal, wherein the surface parameters include the surface radius and the surface curvature; Applying a first pressure to two first edges of the wafer extending along a first direction so that the first edges fit the first curved surface until the first edges form a curved surface structure that matches the shape of a corresponding area in the first curved surface; wherein the first pressure has a plurality of contact points distributed along a meridian direction with the wafer, and the first direction is a direction corresponding to the meridian direction of the target curved surface bent crystal; Applying a second pressure to the wafer so that a side of the wafer close to the first curved surface is closely attached to the first curved surface until the wafer forms a target curved surface structure matching the first curved surface; The applying a second pressure to the entire wafer comprises the following steps: Applying a third pressure distributed at intervals to the entire force-bearing surface of the wafer until the force-bearing area of ​​the wafer forms a curved surface structure that matches the shape of the corresponding area of ​​the first curved surface; A fourth pressure is applied to the entire force-bearing surface of the wafer until the entire force-bearing surface of the wafer is attached to the first curved surface and forms the target curved surface structure; the contact area between the fourth pressure and the wafer is greater than or equal to the area of ​​the force-bearing surface of the wafer.

2. The method for preparing a curved crystal according to claim 1, characterized in that: The applying of the first pressure to the two first edges of the wafer extending in the first direction and the applying of the third pressure distributed at intervals to the entire force-bearing surface of the wafer are achieved by a pre-pressing bending device; The pre-pressing and bending device includes the concave mold and the convex mold, the convex mold has a plurality of deformation strips spaced apart along the first direction, the deformation strips are located on the side of the wafer away from the concave mold, and can be deformed under the action of the first pressure and the third pressure to change from a first state adapted to the initial shape of the wafer to a second state adapted to the shape of the corresponding area of ​​the first curved surface.

3. The method for preparing a curved crystal according to claim 2, characterized in that: The male mold includes a bracket, the deformation strip and a force-applying module corresponding to the deformation strip one by one; the force-applying module is installed on the bracket and is located on the side of the deformation strip away from the female mold, and is used to apply reciprocating pressure to the corresponding deformation strip; each of the force-applying modules includes a plurality of force-applying units arranged at intervals along a second direction; the two ends of the deformation strip in the second direction are respectively connected to the female mold or the bracket for sliding along the second direction, and the second direction is a direction corresponding to the sagittal direction of the target curved surface bent crystal.

4. The method for preparing a curved crystal according to claim 3, characterized in that: The force-applying unit includes a threaded connection piece threadedly connected to the bracket; The pre-pressing and bending device further comprises a first explosion-proof film, and the first explosion-proof film is used to be attached to the back side of the wafer; And / or, the pre-stressing and bending device further comprises a strain gauge, wherein the strain gauge is located between the concave mold and the convex mold and is used to be attached to the wafer to monitor the strain of the wafer.

5. The method for preparing a curved crystal according to claim 1, characterized in that: The application of the fourth pressure to the entire force-bearing surface of the wafer is achieved by a final pressure bending device; The final pressure bending device includes the die, a pressure assembly, a second explosion-proof membrane and a protective film. The pressure assembly has a pressure portion, which is located on the side of the wafer away from the first curved surface. The pressure portion is used to apply pressure to the wafer toward the first curved surface so that the surface of the wafer close to the first curved surface is tightly fitted with the first curved surface. The second explosion-proof membrane is used to be attached to the back side of the wafer, and the protective film is used to be attached to the reflective surface of the wafer.

6. The method for preparing a curved crystal according to claim 5, characterized in that: The pressure applying part includes a pressing plate and a flexible member, wherein the flexible member is installed on a surface of the pressing plate opposite to the first curved surface and is used to contact the wafer; The flexible member is a soft rubber member; in an initial state, the projection area of ​​the flexible member on the first curved surface is smaller than the projection area of ​​the pressure plate on the first curved surface; under pressure, the flexible member can fill the entire space between the pressure plate and the wafer.

7. The method for preparing a curved crystal according to any one of claims 1 to 6, characterized in that: The target curved surface bent crystal is a double curved surface bent crystal, and the curved surface bent crystal preparation method further includes the following steps between applying a first pressure to two first edges of the wafer extending along a first direction and applying a second pressure to the wafer: A fifth pressure is applied to two second edges of the wafer that are opposite to each other in the first direction, so that the second edges fit the first curved surface until the second edges form a curved surface structure that matches the shape of the corresponding area in the first curved surface.

8. The method for preparing a curved crystal according to any one of claims 1 to 6, characterized in that: The process of providing a concave mold and a wafer to be processed comprises the following steps: Providing a concave mold and a wafer to be cut; Obtain the arc length of each side and the center line length of the target curved crystal; According to the arc lengths of the sides and the center line length of the target curved wafer, processing parameters of the flat wafer after flattening are obtained, wherein the processing parameters include the arc lengths of the sides and the center line length of the flat wafer; The wafer to be cut is cut according to the processing parameters to obtain a wafer to be processed.

9. The method for preparing a curved crystal according to any one of claims 1 to 6, characterized in that: The method for preparing a curved crystal further comprises the following steps: providing a substrate; The wafer formed with the target curved surface structure is bonded to the substrate by glue having a coefficient of expansion close to that of the wafer.

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