A low warpage wafer thinning method, system, electronic device and storage medium

Abstract

The application discloses a low-warp wafer thinning method, system, electronic equipment and storage medium, and relates to the technical field of semiconductor manufacturing. The original wafer is mechanically polished to obtain a first wafer, and the first initial thickness of a damage layer is calculated according to the material properties of the original wafer and the processing parameters of mechanical polishing; the first wafer is polished using RIE; the current surface height profile and interference diagram of the first wafer are collected using an interferometer; the real-time thickness of the first wafer is calculated according to the interference diagram, the real-time warping of the first wafer is calculated according to the surface height profile and the real-time thickness; the etching speed of RIE is controlled according to the real-time warping and the real-time thickness until the real-time warping reaches the preset warping range and the real-time thickness reaches the preset thickness range. The real-time thickness and real-time warping of the first wafer can be calculated through the surface height profile and the interference diagram, the etching speed of RIE can be controlled in real time, and the wafer warping can be accurately controlled.

Description

Technical Field

[0001] This invention relates to the field of semiconductor manufacturing technology, and more specifically to a method, system, electronic device, and storage medium for thinning low-warpage wafers. Background Technology

[0002] With the continuous development of the 5G industry, consumer electronics, and power supply electronics, the performance requirements for electronic products are constantly increasing. As a typical representative of third-generation semiconductor materials, silicon carbide (SiC) crystal has characteristics such as a large bandgap, high thermal conductivity, strong critical breakdown field, good lattice matching performance, and high electron mobility. Due to these excellent physicochemical properties and optoelectronic properties, SiC crystal has been widely used as a substrate material in the optoelectronic and microelectronic fields. Due to the requirements of the manufacturing process, high demands are placed on the dimensional accuracy, geometric accuracy, surface cleanliness, and surface microlattice structure of the wafer. Therefore, in hundreds of process flows, thinner wafers cannot be used; only wafers of a certain thickness can be used for transfer and fabrication during the process. Usually, before integrated circuit packaging, it is necessary to remove a certain thickness of excess substrate material from the back side of the wafer, which is called the thinning process.

[0003] During wafer thinning operations, the wafer deforms and warps due to the loss of rigid support from its thickness and stress in the damaged layer, making direct bonding impossible and affecting subsequent circuit integration. However, existing thinning methods do not quantitatively analyze wafer warpage, making precise control of wafer warpage impossible. Summary of the Invention

[0004] The purpose of this invention is to solve the problems of the above-mentioned background technology, and to propose a low-warpage wafer thinning method, system, electronic device and storage medium.

[0005] The objective of this invention can be achieved through the following technical solutions: In a first aspect, the present invention provides a method for thinning a low-warpage wafer, the method comprising: The original wafer is mechanically ground to obtain a first wafer, and the first initial thickness of the damaged layer is calculated based on the material properties of the original wafer and the processing parameters of the mechanical grinding; the first wafer includes the damaged layer and the bottom layer; The first wafer was polished using reactive ion etching (RIE). Use an interferometer to acquire the current surface height profile and interferogram of the first wafer; The real-time thickness of the first wafer is calculated based on the interferogram, and the real-time warpage of the first wafer is calculated based on the surface height profile and the real-time thickness. The etching rate of the RIE is controlled based on the real-time warp and the real-time thickness until the real-time warp reaches a preset warp range and the real-time thickness reaches a preset thickness range.

[0006] Optionally, the material properties include the material hardness, Young's modulus, and fracture toughness of the original wafer; the processing parameters include the average tip angle of the abrasive and the grinding depth per grinding pass. The thickness of the damaged layer is calculated based on the material properties of the original wafer and the machining parameters of the mechanical grinding process, including: Calculate the deformation pressure in the direction perpendicular to the normal direction of the first wafer: in, The deformation pressure, The grinding depth, The average angle of the tip, The hardness of the material; Calculate the first initial thickness of the damaged layer: The first initial thickness, These are preset parameters. The Young's modulus is given. The fracture toughness is given.

[0007] Optionally, calculating the real-time thickness of the first wafer based on the interferogram includes: Determine the current number of interference fringes based on the interferogram; The real-time thickness of the first wafer is calculated based on the number of interference fringes: The real-time thickness is... The wavelength of the light emitted by the interferometer. This represents the current number of interference fringes. is the refractive index of the first wafer.

[0008] Optionally, calculating the real-time warpage of the first wafer based on the surface height profile and the real-time thickness includes: The bow shape of the first wafer is calculated based on the surface height profile. The stress of the damaged layer is calculated based on the bow shape and the real-time thickness. The real-time warpage of the first wafer is calculated based on the stress.

[0009] Optionally, calculating the arcuateness of the first wafer based on the surface height profile includes: The first height, second height, and third height of the first wafer are calculated based on the surface height profile; the first height and the second height are the average height values ​​of all points within a preset range of the edge regions at both ends of the first wafer, and the third height is the average height value of all points within a preset range of the central region of the first wafer; The bow shape of the first wafer is calculated based on the first height, second height, and third height: For the arcuateness, For the first height, This is the second height. This refers to the third height.

[0010] Optionally, the stress of the damaged layer is calculated based on the bow shape and the real-time thickness, including: The stress of the damaged layer, For the arcuateness, Let be the Young's modulus of the first wafer. The real-time thickness is... , , and These are preset parameters.

[0011] Optionally, calculating the real-time warpage of the first wafer based on the stress includes: The underlying layer thickness and real-time damage layer thickness are calculated based on the second initial thickness of the first wafer, the first initial thickness, and the real-time thickness. The real-time warpage of the first wafer is calculated based on the stress, the underlying layer thickness, and the real-time damage layer thickness: The real-time warpage. The Poisson's ratio of the first wafer. For the stress, The real-time damage layer thickness is... The diameter of the first wafer is denoted as . The thickness of the bottom layer. This is the Young's modulus of the first wafer.

[0012] A second aspect of the present invention also provides a low-warpage wafer thinning system, comprising a grinding module, a polishing module, a data acquisition module, a calculation module, and a control module; wherein: The grinding module is used to mechanically grind the original wafer to obtain a first wafer, and to calculate the first initial thickness of the damaged layer based on the material properties of the original wafer and the processing parameters of the mechanical grinding; the first wafer includes the damaged layer and the bottom layer; The polishing module is used to polish the first wafer using reactive ion etching (RIE). The acquisition module is used to acquire the current surface height profile and interferogram of the first wafer using an interferometer; The calculation module is used to calculate the real-time thickness of the first wafer based on the interference pattern, and to calculate the real-time warpage of the first wafer based on the surface height profile and the real-time thickness. The control module is used to control the etching rate of the RIE according to the real-time warpage and the real-time thickness until the real-time warpage reaches a preset warpage range and the real-time thickness reaches a preset thickness range.

[0013] According to a third aspect of the present invention, an electronic device is also provided, including a processor, a communication interface, a memory, and a communication bus, wherein the processor, the communication interface, and the memory communicate with each other through the communication bus. Memory, used to store computer programs; When a processor executes a program stored in memory, it implements any of the steps described above.

[0014] In a fourth aspect, the present invention also provides a computer-readable storage medium, characterized in that the computer-readable storage medium stores a computer program, which, when executed by a processor, implements any of the steps described above.

[0015] This invention provides a low-warpage wafer thinning method, comprising: mechanically grinding a raw wafer to obtain a first wafer, and calculating a first initial thickness of a damaged layer based on the material properties of the raw wafer and the processing parameters of the mechanical grinding; the first wafer includes a damaged layer and a bottom layer; polishing the first wafer using reactive ion etching (RIE); acquiring a current surface height profile and interferogram of the first wafer using an interferometer; calculating the real-time thickness of the first wafer based on the interferogram, and calculating the real-time warpage of the first wafer based on the surface height profile and the real-time thickness; controlling the etching rate of the RIE based on the real-time warpage and the real-time thickness until the real-time warpage reaches a preset warpage range and the real-time thickness reaches a preset thickness range. By calculating the real-time thickness and real-time warpage of the first wafer using the surface height profile and the interferogram, and controlling the etching rate of the RIE in real time, precise control of wafer warpage can be achieved. Attached Figure Description

[0016] The invention will now be further described with reference to the accompanying drawings.

[0017] Figure 1 A flowchart of a low-warpage wafer thinning method provided in an embodiment of the present invention; Figure 2 A system block diagram of a low warpage wafer thinning system provided in an embodiment of the present invention; Figure 3 This is a schematic diagram of the structure of an electronic device provided in an embodiment of the present invention. Detailed Implementation

[0018] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0019] This invention provides a method for thinning wafers with low warpage. See also... Figure 1 , Figure 1 This is a flowchart illustrating a low-warpage wafer thinning method provided in an embodiment of the present invention. The method may include the following steps: S101, the original wafer is mechanically ground to obtain the first wafer, and the first initial thickness of the damaged layer is calculated based on the material properties of the original wafer and the processing parameters of mechanical grinding.

[0020] S102, the first wafer is polished using reactive ion etching (RIE).

[0021] S103, use an interferometer to acquire the current surface height profile and interferogram of the first wafer.

[0022] S104, calculate the real-time thickness of the first wafer based on the interferogram, and calculate the real-time warpage of the first wafer based on the surface height profile and the real-time thickness.

[0023] S105 controls the etching rate of the RIE based on real-time warp and real-time thickness until the real-time warp reaches a preset warp range and the real-time thickness reaches a preset thickness range.

[0024] The first wafer includes a damage layer and a bottom layer.

[0025] Based on the low warpage wafer thinning method provided by the embodiments of the present invention, the real-time thickness and real-time warpage of the first wafer can be calculated by using surface height profile and interference diagram, and the etching rate of RIE can be controlled in real time, thereby enabling precise control of wafer warpage.

[0026] In one implementation, the mechanical grinding of the original wafer can be performed by grinding or abrasive wheel thinning. Typically, abrasive wheel thinning is used for hard materials such as sapphire or silicon wafers, while grinding is used for wafer materials such as InP or GaSa.

[0027] In one implementation, reactive ion etching (RIE) involves exposing the wafer to a uniform, highly dissociated plasma, and using an electrostatic chuck to control the wafer temperature. This allows the wafer to react with the plasma, achieving the purpose of polishing the wafer.

[0028] In one embodiment, the material properties include the material hardness, Young's modulus, and fracture toughness of the original wafer; the processing parameters include the average tip angle of the abrasive and the grinding depth per grinding pass. The thickness of the damaged layer is calculated based on the material properties of the original wafer and the machining parameters of the mechanical grinding process, including: Calculate the deformation pressure in the direction perpendicular to the normal of the first wafer: (1) in, For deformation pressure, For grinding depth, The average angle at the tip. Material hardness; Calculate the first initial thickness of the damaged layer: (2) The first initial thickness, These are preset parameters. This is Young's modulus of elasticity. This refers to fracture toughness.

[0029] In one embodiment, calculating the real-time thickness of the first wafer based on the interferogram includes: Determine the current number of interference fringes based on the interferogram; The real-time thickness of the first wafer is calculated based on the number of interference fringes: (3) For real-time thickness, The wavelength of the light emitted by the interferometer. This represents the current number of interference fringes. is the refractive index of the first wafer.

[0030] In one embodiment, calculating the real-time warpage of the first wafer based on the surface height profile and real-time thickness includes: Calculate the bow shape of the first wafer based on the surface height profile; The stress of the damaged layer is calculated based on the bow shape and real-time thickness. The real-time warpage of the first wafer is calculated based on stress.

[0031] In one embodiment, calculating the bow shape of the first wafer based on the surface height profile includes: The first height, second height, and third height of the first wafer are calculated based on the surface height profile. The first height and second height are the average height values ​​of all points within a preset range of the edge regions at both ends of the first wafer, and the third height is the average height value of all points within a preset range of the central region of the first wafer. Calculate the arcuate shape of the first wafer based on the first, second, and third heights: (4) For the arcuate shape, As the highest point, The second highest altitude, It is the third highest altitude.

[0032] In one embodiment, calculating the stress of the damaged layer based on the bow shape and real-time thickness includes: (5) For the stress of the damaged layer, For the arcuate shape, This represents the Young's modulus of the first wafer. For real-time thickness, , , and These are preset parameters.

[0033] In one embodiment, calculating the real-time warpage of the first wafer based on stress includes: The underlying layer thickness and real-time damage layer thickness are calculated based on the second initial thickness, the first initial thickness, and the real-time thickness of the first wafer. The real-time warpage of the first wafer is calculated based on stress, underlying layer thickness, and real-time damage layer thickness: (6) For real-time warp, The Poisson's ratio of the first wafer. For stress, For real-time damage layer thickness, The diameter of the first wafer. For the thickness of the bottom layer, This is the Young's modulus of the first wafer.

[0034] Based on the same inventive concept, embodiments of the present invention provide a low-warpage wafer thinning system. See also Figure 2 , Figure 2 This is a system block diagram of a low-warpage wafer thinning system provided in an embodiment of the present invention. The system includes a grinding module, a polishing module, a data acquisition module, a calculation module, and a control module; wherein: The grinding module is used to mechanically grind the original wafer to obtain a first wafer, and to calculate the first initial thickness of the damaged layer based on the material properties of the original wafer and the processing parameters of the mechanical grinding; the first wafer includes a damaged layer and a bottom layer; A polishing module for polishing the first wafer using reactive ion etching (RIE); The acquisition module is used to acquire the current surface height profile and interferogram of the first wafer using an interferometer; The calculation module is used to calculate the real-time thickness of the first wafer based on the interferogram, and to calculate the real-time warpage of the first wafer based on the surface height profile and the real-time thickness. The control module is used to control the etching rate of the RIE based on real-time warp and real-time thickness until the real-time warp reaches a preset warp range and the real-time thickness reaches a preset thickness range.

[0035] Based on the low warpage wafer thinning system provided in this embodiment of the invention, the real-time thickness and warpage of the first wafer can be calculated through surface height profile and interference diagram, and the etching rate of RIE can be controlled in real time, thereby enabling precise control of wafer warpage.

[0036] This invention also provides an electronic device, such as... Figure 3 As shown, it includes a processor 301, a communication interface 302, a memory 303, and a communication bus 304, wherein the processor 301, the communication interface 302, and the memory 303 communicate with each other through the communication bus 304. Memory 303 is used to store computer programs; When processor 301 executes a program stored in memory 303, it performs the following steps: The original wafer is mechanically ground to obtain a first wafer, and the first initial thickness of the damaged layer is calculated based on the material properties of the original wafer and the processing parameters of the mechanical grinding; the first wafer includes the damaged layer and the bottom layer; The first wafer was polished using reactive ion etching (RIE). Use an interferometer to acquire the current surface height profile and interferogram of the first wafer; The real-time thickness of the first wafer is calculated based on the interferogram, and the real-time warpage of the first wafer is calculated based on the surface height profile and the real-time thickness. The etching rate of the RIE is controlled based on the real-time warp and the real-time thickness until the real-time warp reaches a preset warp range and the real-time thickness reaches a preset thickness range.

[0037] The communication bus mentioned in the above electronic devices can be a Peripheral Component Interconnect (PCI) bus or an Extended Industry Standard Architecture (EISA) bus, etc. This communication bus can be divided into address bus, data bus, control bus, etc. For ease of illustration, only one thick line is used to represent it in the diagram, but this does not mean that there is only one bus or one type of bus.

[0038] The communication interface is used for communication between the aforementioned electronic devices and other devices.

[0039] The memory may include random access memory (RAM) or non-volatile memory (NVM), such as at least one disk storage device. Optionally, the memory may also be at least one storage device located remotely from the aforementioned processor.

[0040] The processors mentioned above can be general-purpose processors, including central processing units (CPUs), network processors (NPs), etc.; they can also be digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, or discrete hardware components.

[0041] In another embodiment of the present invention, a computer-readable storage medium is also provided, which stores a computer program that, when executed by a processor, implements the steps of any of the above-described wafer thinning methods.

[0042] In another embodiment of the present invention, a computer program product containing instructions is also provided, which, when run on a computer, causes the computer to perform any of the wafer thinning methods described above.

[0043] In the above embodiments, implementation can be achieved, in whole or in part, through software, hardware, firmware, or any combination thereof. When implemented in software, it can be implemented, in whole or in part, as a computer program product. The computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on a computer, all or part of the processes or functions described in the embodiments of the present invention are generated. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions can be stored in a computer-readable storage medium or transmitted from one computer-readable storage medium to another. For example, the computer instructions can be transmitted from one website, computer, server, or data center to another website, computer, server, or data center via wired (e.g., coaxial cable, fiber optic, digital subscriber line (DSL)) or wireless (e.g., infrared, wireless, microwave, etc.) means. The computer-readable storage medium can be any available medium accessible to a computer or a data storage device such as a server or data center that integrates one or more available media. The available medium can be a magnetic medium (e.g., floppy disk, hard disk, magnetic tape), an optical medium (e.g., DVD), or a semiconductor medium (e.g., solid-state disk (SSD)).

[0044] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0045] The various embodiments in this specification are described in a related manner. Similar or identical parts between embodiments can be referred to mutually. Each embodiment focuses on describing the differences from other embodiments. In particular, the descriptions of systems, electronic devices, and storage media are relatively simple because they are fundamentally similar to the method embodiments; relevant parts can be referred to the descriptions of the method embodiments.

[0046] The foregoing has provided a detailed description of one embodiment of the present invention, but this description is merely a preferred embodiment and should not be construed as limiting the scope of the invention. All equivalent variations and modifications made within the scope of the claims of this invention should still fall within the patent coverage of this invention.

Claims

1. A method for thinning a low-warpage wafer, characterized in that, The method includes: The original wafer is mechanically ground to obtain a first wafer, and the first initial thickness of the damaged layer is calculated based on the material properties of the original wafer and the processing parameters of the mechanical grinding; the first wafer includes the damaged layer and the bottom layer; The first wafer was polished using reactive ion etching (RIE). Use an interferometer to acquire the current surface height profile and interferogram of the first wafer; The real-time thickness of the first wafer is calculated based on the interferogram, and the real-time warpage of the first wafer is calculated based on the surface height profile and the real-time thickness. The etching rate of the RIE is controlled based on the real-time warpage and the real-time thickness until the real-time warpage reaches a preset warpage range and the real-time thickness reaches a preset thickness range. The material properties include the material hardness, Young's modulus, and fracture toughness of the original wafer; the processing parameters include the average tip angle of the abrasive and the grinding depth per grinding cycle. The first initial thickness of the damaged layer is calculated based on the material properties of the original wafer and the machining parameters of the mechanical polishing, including: Calculate the deformation pressure in the direction perpendicular to the normal direction of the first wafer: ； in, The deformation pressure, The grinding depth, The average angle of the tip, The hardness of the material; Calculate the first initial thickness of the damaged layer: The first initial thickness, These are preset parameters. The Young's modulus is given. The fracture toughness is mentioned above; Calculating the real-time warpage of the first wafer based on the surface height profile and the real-time thickness includes: The bow shape of the first wafer is calculated based on the surface height profile. The stress of the damaged layer is calculated based on the bow shape and the real-time thickness. The real-time warpage of the first wafer is calculated based on the stress. Calculating the real-time warpage of the first wafer based on the stress includes: The underlying layer thickness and real-time damage layer thickness are calculated based on the second initial thickness of the first wafer, the first initial thickness, and the real-time thickness. The real-time warpage of the first wafer is calculated based on the stress, the underlying layer thickness, and the real-time damage layer thickness: ； The real-time warpage. The Poisson's ratio of the first wafer. For the stress, The real-time damage layer thickness is... The diameter of the first wafer is denoted as . The thickness of the bottom layer. This is the Young's modulus of the first wafer.

2. The low-warpage wafer thinning method according to claim 1, characterized in that, Calculating the real-time thickness of the first wafer based on the interferogram includes: Determine the current number of interference fringes based on the interferogram; The real-time thickness of the first wafer is calculated based on the number of interference fringes: ； The real-time thickness is... The wavelength of the light emitted by the interferometer. This represents the current number of interference fringes. is the refractive index of the first wafer.

3. The method for thinning a low-warpage wafer according to claim 2, characterized in that, Calculating the bow shape of the first wafer based on the surface height profile includes: The first height, second height, and third height of the first wafer are calculated based on the surface height profile; the first height and the second height are the average height values ​​of all points within a preset range of the edge regions at both ends of the first wafer, and the third height is the average height value of all points within a preset range of the central region of the first wafer; The bow shape of the first wafer is calculated based on the first height, second height, and third height: ； For the arcuateness, For the first height, This is the second height. This refers to the third height.

4. An electronic device, characterized in that, It includes a processor, a communication interface, a memory, and a communication bus, wherein the processor, the communication interface, and the memory communicate with each other through the communication bus; Memory, used to store computer programs; The processor, when executing a program stored in memory, implements the steps of the low warpage wafer thinning method according to any one of claims 1-3.

5. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a computer program that, when executed by a processor, implements the steps of the low-warpage wafer thinning method according to any one of claims 1-3.

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