Manufacturing method with temporary protection of microstructures
By using the material covering wafers and base wafers to lock and connect the microstructures in the semiconductor component manufacturing process, the problem of microstructures being susceptible to contamination and damage during the manufacturing process is solved, and the protection and flexible process selection of the entire process are achieved.
Patent Information
- Application Number
- CN202380090388.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Priority Date
- 2023-01-03
- Filing Date
- 2023-11-23
- Publication Date
- 2025-08-08
AI Technical Summary
During the manufacturing process of semiconductor components, microstructures are susceptible to contamination and mechanical damage, especially when chemicals and sharding are used, they are difficult to effectively protect.
By arranging the cover wafers on the base wafer and connecting in a material-locked manner, a wafer assembly is formed to cover the wafer to protect the microstructure, and then removing the cover wafers if necessary to expose the microstructure.
Protect microstructures from contamination and damage throughout the manufacturing process, maintain flexibility in process selection, and avoid the impact of particles and chemicals on microstructures due to sawing and cleaning.
Smart Images
Figure CN120457086A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to a method for producing a semiconductor component with microstructures, in which method a base wafer with a multiplicity of microstructures is provided. Background Art
[0002] The production of open MEMS structures, or microstructures, in semiconductor components presents a challenge in protecting these sensitive microstructures. In particular, they must be protected from contamination, such as by particles, liquid chemicals, and required process substances, as well as from mechanical damage. In the case of particle contamination, the microstructures can become clogged and subsequently lose their functionality. Chemical contamination can also lead to adhesion of the microstructures, which in turn no longer function as intended.
[0003] In order to protect the microstructures from contamination due to particles, methods are already known that are implemented in clean rooms. However, the problem is: protecting the microstructures from the chemicals that must be used during manufacturing. In addition, during the further processing of the wafer, during the slicing into MEMS chips and the subsequent assembly and connection technologies, the open microstructures are potentially susceptible to damage and contamination. In particular, when slicing the wafers into MEMS chips with open microstructures, conventional sawing processes using diamond saw blades and water for cleaning are excluded, which limits the choice of processes for manufacturing the wafers. Summary of the Invention
[0004] The object underlying the present invention can be seen as providing a wafer-based production method for microstructures that are open to the environment and that protects the microstructures from harmful influences at least during the production process.
[0005] This object is achieved by the corresponding subject matter of the independent claims. Advantageous configurations of the invention are the subject matter of the respective dependent claims.
[0006] According to one aspect of the present invention, a method for manufacturing semiconductor components with microstructures is provided. In one step of the method, a base wafer with a large number of microstructures is provided. The microstructures can be configured, for example, as MEMS structures required for operating micromirrors, μ-phones, MEMS speakers, pressure sensors, environmental sensors, and similar devices. Such components with microstructures require communication with the environment and, therefore, cannot be hermetically packaged as semiconductor components or chips. Therefore, such microstructures are potentially exposed to risks of damage and contamination throughout the entire process chain (wafer processing, slicing, AVT, etc.).
[0007] In a further step of the method, a cover wafer is placed on the base wafer and materially bonded to it to form a wafer assembly. In this wafer assembly, the microstructure is sealed off from the environment at least on one side by the placed cover wafer. This step protects the microstructure during the entire manufacturing process.
[0008] After applying at least one cover wafer, which can be applied unilaterally or bilaterally to the base wafer, at least one production step and / or processing step and / or singulation step is performed. This allows for an unrestricted selection of available production processes, eliminating the need to compromise on the production technology of the semiconductor components.
[0009] In a further step, which can optionally be configured as a final step, at least a portion of the cover wafer or at least a portion of the singulated segments of the cover wafer is removed from the base wafer or from the singulated segments of the base wafer.
[0010] Thus, at least one previously applied cover wafer can be implemented before or after the singulation step. For example, the choice of technology for singulating semiconductor components from the wafer assembly can provide the decision as to whether to remove the cover wafer or a section of the cover wafer before or after the singulation step.
[0011] In this case, at least one cover wafer is removed before slicing. After the singulation step or slicing of the wafer assembly, the cover wafer and the base wafer with the microstructure are connected to each other in the form of a plurality of segments, each of which is separated from each other after slicing.
[0012] This method allows the microstructure to be protected during the entire manufacturing process, for example by hermetic bonding of at least one cover wafer made of silicon or glass.
[0013] By covering the wafer, the microstructure is protected and the system or wafer assembly can be further manufactured or processed throughout the entire manufacturing process without being restricted to a single production step.
[0014] This also allows unrestricted processes on the back side of the base wafer, which in an open system could lead to damage to the microstructure. The at least one cover wafer acts as a structural reinforcement.
[0015] For example, with this method, wafer components can also be singulated by conventional sawing. In the case of open microstructures, such singulation would be impossible due to the use of water (for cooling and cleaning) and the abrasive dust (particles) generated during sawing.
[0016] After the entire system is completed or the manufacturing process is finished, the microstructures in the wafer assembly can be separated from the cover wafer as a whole or as singulated MEMS chips in the form of semiconductor components. This separation can be performed, for example, by horizontal slicing.
[0017] According to one aspect of the present invention, a sensor component is provided. The sensor component can be configured, for example, in the form of a microelectromechanical system (MEMS) and has at least one section of a base wafer with at least one microstructure.
[0018] In one embodiment, the cover wafer is connected to the base wafer by direct wafer bonding or anodic bonding, by sealing glass bonding, or by eutectic bonding. This allows at least one cover wafer to be used to hermetically seal the microstructures on the base wafer based on various connection methods.
[0019] According to another embodiment, at least a portion of the cover wafer is separated from the base wafer by horizontal stealth dicing of the bonding layer or of the cover wafer. Thus, the cover wafer or a portion or section of the cover wafer can be removed from the base wafer, for example, by so-called Kabra dicing. This separation method allows for the rapid and precise removal of previously sealed microstructures with minimal risk of contamination, for example, by particles.
[0020] According to another embodiment, at least a portion of the singulated segments of the cover wafer are separated from the singulated segments of the base wafer or from the singulated segments of the cover wafer by horizontal stealth cutting of the bonding layer.
[0021] Depending on the configuration, the cover wafer or a section of the cover wafer can be separated from the base wafer completely along the connecting layer. In alternative or additional configurations, the cover wafer or a section of the cover wafer can also be separated at a vertical position offset from the connecting layer. In this case, fragments or remnants of the cover wafer may remain on the base wafer or the section of the base wafer.
[0022] According to another embodiment, a cover wafer structured toward the base wafer is arranged on the base wafer and connected to it. Instead of an unstructured or smoothly configured cover wafer, a structure can be produced on the cover wafer that is present in the region of the microstructures. Thus, microstructures protruding from the base wafer can be protected by the cover wafer, for example. Alternatively, the microstructures can be protected by a cavity or a plurality of cavities introduced into the cover wafer. Advantageously, a cavity can be provided in the cover wafer for each microstructure, which cavity is located directly above the microstructure to be protected.
[0023] According to another embodiment, after at least one production step and / or processing step and / or singulation step, the microstructure is exposed by at least partially removing the cover wafer. For example, a so-called invisible layer can be applied to the material of the cover wafer using a suitable laser above the wafer bonding locations as a connecting layer. Subsequently, the cover wafer can be removed along the (predetermined) break locations.
[0024] This is particularly simple technically to act on previously singulated MEMS chips. Here, the sections covering the wafer can be simply lifted by conventional pick-and-place processes with corresponding pick-up tools.
[0025] According to another embodiment, for at least partial removal of the cover wafer, at least one horizontally running stealth layer is introduced into the cover wafer, and separation is carried out along this horizontally running stealth layer.
[0026] If the cover wafer or a portion of the cover wafer is separated after the wafer assembly has been singulated, at least one horizontally extending invisible layer is introduced into the singulated or separated sections of the cover wafer, and the separation is performed along this horizontally extending invisible layer. As a result, the microstructure can be exposed and supplied to the intended use only at the end of the entire process chain.
[0027] According to another embodiment, a plurality of semiconductor components with exposed microstructures are produced by at least partially separating singulated sections of a cover wafer. In an alternative configuration, a plurality of semiconductor components with exposed microstructures are produced by at least partially separating and subsequently singulating a cover wafer. These measures allow protection of the individual semiconductor components before or after singulation. This allows the production method to be carried out efficiently without concern for possible contamination of the microstructures. BRIEF DESCRIPTION OF THE DRAWINGS
[0028] A preferred embodiment of the present invention will be explained in more detail below with the aid of a highly simplified schematic diagram. Here, it is shown:
[0029] Figure 1 A cross-sectional view of a wafer assembly according to the present invention according to one embodiment is provided for illustrating a method according to the present invention.
[0030] Figure 2 A cross-sectional view of a wafer assembly according to another embodiment of the present invention is provided for illustrating the method according to the present invention.
[0031] Figure 3 a cross-sectional view of a wafer assembly according to the invention with an introduced invisible layer for illustrating the method according to the invention,
[0032] Figure 4a cross-sectional view of a base wafer with a cover wafer partially removed along the stealth layer, for illustrating the method according to the invention, and
[0033] Figure 5 Cross-sectional view for illustrating the method according to the invention according to another exemplary embodiment. DETAILED DESCRIPTION
[0034] exist Figure 1 1 shows a cross-sectional view of a wafer assembly 1 according to an embodiment of the present invention for illustrating a method according to the present invention. The method is used to produce a semiconductor component 2 with a microstructure 4. The semiconductor component 2 with the microstructure 4 after being divided is exemplarily Figure 5 In display.
[0035] In one step of the method, a base wafer 6 with a plurality of microstructures 4 is provided. The microstructures 4 are exemplarily configured as MEMS structures. In a further step of the method, a cover wafer 8 is arranged on the base wafer 6 and connected to the base wafer 6 in a material-bonded manner to form a cover wafer 8. Figure 1 and Figure 2 . In this wafer assembly 1 , the microstructure 4 is sealed on one side with respect to the environment U by an arranged cover wafer 8 .
[0036] exist Figure 1 In the embodiment, a cover wafer 8 structured toward the base wafer 6 is arranged on the base wafer 6 and connected to the base wafer 6 by means of a connecting layer 10. By structuring the cover wafer 8, a large number of cavities 12 or recesses are introduced into the cover wafer 8. In this case, a cavity 12 is provided in the cover wafer 8 for each microstructure 4 in order to accommodate the corresponding microstructure 4.
[0037] exist Figure 2 1 shows another cross-sectional view of a wafer assembly 1 according to the invention according to another embodiment for illustrating the method according to the invention. An alternative wafer assembly 1 is shown here in which an unstructured cover wafer 8 is used to hermetically seal or protect the microstructure 4.
[0038] The method Figure 1 and Figure 2 The steps shown in FIG. 4 make it possible to protect the microstructure 4 during the entire manufacturing process. After applying at least one cover wafer 8, which can be applied unilaterally or bilaterally to the base wafer 6, at least one production step and / or processing step and / or singulation step is performed, which step is not described in greater detail for the sake of simplicity.
[0039] Figure 3A cross-sectional view of a wafer assembly 1 according to the invention with an introduced stealth layer 14 is shown for illustrating further steps of the method according to the invention. Here, a horizontally extending stealth layer 14 is introduced into the cover wafer 8, for example, at a vertical position of the wafer assembly 1 offset from the connecting layer 10.
[0040] In a subsequent step, the cover wafer 8 is partially separated along the horizontally extending invisible layer 14. The result of this separation is Figure 4 , which shows a cross-sectional view of a base wafer 6 with a cover wafer 8 partially removed along the invisible layer 14. Figure 4 , also shown are the remaining fragments 16 of the cover wafer 8 , which are connected to the base wafer 6 by means of the connecting layer 10 .
[0041] By at least partially removing the cover wafer 8 after at least one production step and / or processing step, the microstructure 4 is exposed. For example, a so-called invisible layer 14 can be applied with a suitable laser to the material of the cover wafer 8 above the wafer bonding location as the connecting layer 10. Subsequently, the cover wafer 8 can be removed along the (predetermined) breaking location.
[0042] Depending on the configuration of the method, a singulation step can subsequently be carried out in order to produce a plurality of semiconductor components 2 .
[0043] Figure 3 and Figure 4 Exemplarily illustrate the Figure 1 The further processing of the wafer assembly 1 with the structured cover wafer 8 shown in FIG.
[0044] exist Figure 5 Detailed Description of the Invention A sectional view illustrating the method according to the invention according to another exemplary embodiment is shown in FIG.
[0045] Here, in one step, Figure 1 The wafer assembly 1 shown in FIG is divided into segments 3. For example, the wafer assembly 1 can be sliced by conventional sawing.
[0046] After the singulation step or the slicing of the wafer assembly 1, the cover wafer 8 and the base wafer 6 with the microstructure 4 are present in a mutually connected manner in the form of a plurality of segments 7, 9, which are separated from one another after slicing. In this process, at least a portion of the slicing segments 9 of the cover wafer 8 is removed from the slicing segments 7 of the base wafer 6.
Claims
1. A method for producing a semiconductor component (2) with a microstructure (4), wherein: - providing a base wafer (6) with a plurality of microstructures (4), - arranging a cover wafer (8) on the base wafer (6) and connecting it to the base wafer (6) in a material-locking manner in order to form a wafer assembly (1), - the microstructure (4) is sealed at least on one side with respect to the environment (U) by the arranged cover wafer (8), - performing at least one production step and / or processing step and / or segmentation step, - removing at least a portion of the cover wafer (8) or at least a portion of the singulated sections (9) of the cover wafer (8) from the base wafer (6) or from the singulated sections (7) of the base wafer (6).
2. The method according to claim 1, wherein The cover wafer (8) is connected to the base wafer (6) by anodic bonding, by sealing glass bonding or by eutectic bonding.
3. The method according to claim 1 or 2, wherein: At least a portion of the cover wafer (8) is separated from the base wafer (6) by horizontal stealth cutting of the bonding layer or the cover wafer (8).
4. The method according to any one of claims 1 to 3, wherein At least a portion of the singulated segments (9) of the cover wafer (8) is separated from the singulated segments (7) of the base wafer (6) or from the singulated segments (9) of the cover wafer (8) by horizontal stealth cutting of the bonding layer.
5. The method according to any one of claims 1 to 4, wherein A cover wafer (8) structured in the direction of the base wafer (6) is arranged on the base wafer (6) and connected to the base wafer (6).
6. The method according to any one of claims 1 to 5, wherein After the at least one production step and / or processing step and / or singulation step, the microstructure (4) is exposed by at least partially removing the cover wafer (8).
7. The method according to any one of claims 1 to 6, wherein In order to at least partially remove the cover wafer (8) or the section (9) of the cover wafer (8), at least one horizontally extending invisible layer (14) is introduced into the cover wafer (8) or the section (9) of the cover wafer (8), and separation is performed along the horizontally extending invisible layer (14).
8. The method according to any one of claims 1 to 7, wherein Producing a plurality of semiconductor components (2) with exposed microstructures (4) by at least partially separating the singulated sections (9) of the cover wafer (8); or A plurality of semiconductor components (2) with exposed microstructures (4) are produced by at least partial separation and subsequent singulation of the cover wafer (8).