A new type of manufacturing process for interdigitated strips
By adopting multiple film formation and ion etching cycle operations in the interfinger manufacturing process, the problems of high stress and easy fall off of metal film layers in traditional processes are solved, and high-quality, high-density and low-stress metal film layers are prepared, which improves product performance and reliability.
Patent Information
- Application Number
- CN202411906807.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-24
- Publication Date
- 2025-04-04
AI Technical Summary
When preparing metal film layers such as AlCu, Cu, Cr, Ag, Pt, the traditional metal interdigital strip process, due to the large thermal expansion coefficient of these metals, the number of defects and large stresses, and the metal film layer is prone to fall off, affecting RF electrical performance and reliability.
Multiple film formation and ion etching processes were used for cycle operations to prepare a metal film layer with few defects, high density, low stress and not easy to fall off. The specific steps include photoresist coating and evaporation on the substrate, and then reducing the stress of the metal film layer through ion beam etching, and alternate operations through multiple electron beam evaporation and ion beam etching to ensure that the stress of the metal film layer is greatly reduced after each operation.
Through this process, defects and stress of the metal film layer are reduced, film formation density and adhesion are improved, the risk of film layer falling off is significantly reduced, and the appearance yield, RF performance yield and reliability of the product are improved.
Smart Images
Figure CN119766179A_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the field of surface acoustic wave devices, and in particular relates to a novel manufacturing process of interdigitated strips. Background Art
[0002] With the popularization of 5G communication, terminal products have put forward higher requirements for filters of key components in the 5G field (high Q value, low insertion loss, high power, etc.). To meet these requirements, the process of ordinary metal Al evaporation cross-finger strips can no longer meet the design requirements, and metals with higher anti-electron mobility and higher density are needed to replace metal Al, usually AlCu, Cu, Cr, Ag, Pt and other metals or a combination of multiple metals to replace metal Al.
[0003] The main process routes of traditional SAW, TC-SAW, and TF-SAW processes on wafers include: preparing a metal interdigitated structure, covering the temperature compensation layer on the interdigitated structure, preparing a second metal layer, preparing a protective layer, and other processes. The preparation of the metal interdigitated structure is mainly through a one-time forming process of electron beam evaporation. However, when this process is used to prepare thick metal films such as AlCu, Cu, Cr, Ag, and Pt, due to the large thermal expansion coefficients of these metals, as the thickness of the metal film increases, it will cause more defects and greater stress. After the electron beam evaporated metal is peeled off, the evaporated metal film layer will fall off, affecting the RF electrical performance and reliability of the product. Summary of the invention
[0004] The present invention aims to solve the problem that the existing metal film layer is easy to fall off, and proposes a new interdigitated strip manufacturing process. The present invention uses multiple film forming and ion etching processes for cyclic operation to prepare a metal film layer with few defects, high density, low stress and not easy to fall off, thereby improving the product appearance yield, RF performance yield and reliability.
[0005] In order to achieve the above object, the present invention is implemented by the following technical scheme: A new type of interdigitated strip manufacturing process is carried out according to the following steps: Step 1) coating, exposing and developing photoresist on the substrate so that the photoresist shape presents a corresponding finger pattern; Step 2) performing a first metal evaporation on the photoresist and the substrate by electron beam evaporation method; Step 3) etching the metal and photoresist after the first evaporation indiscriminately by ion beam in the electron beam evaporation equipment; Step 4) performing a second metal evaporation on the etched first metal layer by electron beam evaporation to complete the preparation of the first metal layer; Step 5) After the second metal evaporation is completed, other metal layers are evaporated; Step 6) Using a lift-off process, the photoresist layer and the metal deposited on the photoresist layer are peeled off to form interdigitated electrodes.
[0006] Furthermore, the thickness of the ion beam etching in step 3) is 10-30% of the thickness of the first evaporated metal.
[0007] Furthermore, the number of cycles of the alternating electron beam evaporation and ion beam etching in step 3), step 4) and step 5) is 2 times, 3 times, or 4 times.
[0008] Furthermore, after step 4), the second metal vapor deposition layer is again indiscriminately etched by ion beam in the electron beam evaporation equipment. After the etching is completed, the second metal layer is prepared on the first metal layer by alternating electron beam evaporation and ion beam etching.
[0009] Furthermore, the stress of the first metal layer is greater than the stress of the second metal layer.
[0010] Compared with the prior art, the beneficial effects of the present invention are as follows: the present invention adopts a process method of multiple growths and ion etching when electronically evaporating a metal layer with large stress. After the first growth is completed, ion etching is performed to reduce the defects of the metal film layer, increase the film density, increase the roughness of the metal film layer and reduce the stress. When the second growth is performed, the adhesion between the second layer of metal and the bottom metal is better. The metal grown in two or more cycles has fewer defects and lower stress than the metal grown in a single cycle, and the risk of film shedding is greatly reduced.
[0011] The present invention is different from the traditional electron beam evaporation process. By improving the special metal evaporation process, the stress and defects of the metal film layer are reduced, the quality of the metal film layer is improved, and the risk of the metal film layer falling off after peeling is reduced, thereby ultimately improving the product appearance yield, RF performance yield and reliability, thereby preparing a high-performance, high-power and high-reliability filter. BRIEF DESCRIPTION OF THE DRAWINGS
[0012] Figure 1 Schematic diagram of the first metal preparation.
[0013] Figure 2 Schematic diagram of ion beam etching.
[0014] Figure 3 Schematic diagram of the second electron beam evaporation.
[0015] Figure 4 Schematic diagram of electron beam evaporation of other metals.
[0016] Figure 5 Schematic diagram of metal stripping.
[0017] Figure 6Schematic diagram of the multilayer metal preparation process.
[0018] Figure 7 This is a photo of the metal strips falling off.
[0019] Figure 8 This is a normal photo of a metal interdigitated strip. DETAILED DESCRIPTION
[0020] The following will describe the implementation methods of the present invention in detail with reference to the accompanying drawings and examples, so as to fully understand and implement the implementation process of how the present invention applies technical means to solve technical problems and achieve technical effects. Example
[0021] A novel interdigitated strip manufacturing process is carried out according to the following steps: Step 1) coating, exposing and developing photoresist on the substrate so that the photoresist shape presents a corresponding finger pattern; Step 2) If Figure 1 As shown, a first metal evaporation is performed on the photoresist and the substrate by an electron beam evaporation method; Step 3) If Figure 2 As shown, the metal and photoresist after the first evaporation are etched indiscriminately by an ion beam in the electron beam evaporation equipment, and the thickness of the ion beam etching is 10% of the thickness of the first evaporation metal; Step 4) If Figure 3 As shown, a second metal evaporation is performed on the etched first metal layer by electron beam evaporation to complete the preparation of the first metal layer; Step 5) If Figure 4 As shown, after the second metal evaporation is completed, other metal layers are evaporated; Step 6) If Figure 5 As shown, a lift-off process is used to peel off the photoresist layer and the metal deposited on the photoresist layer to form interdigital electrodes. Example
[0022] A novel interdigitated strip manufacturing process is carried out according to the following steps: Step 1) coating, exposing and developing photoresist on the substrate so that the photoresist shape presents a corresponding finger pattern; Step 2) If Figure 1 As shown, a first metal evaporation is performed on the photoresist and the substrate by an electron beam evaporation method; Step 3) If Figure 2 As shown, the metal and photoresist after the first evaporation are etched indiscriminately by ion beam in the electron beam evaporation equipment, and the thickness of the ion beam etching is 15% of the thickness of the first evaporation metal; Step 4) If Figure 3As shown, a second metal evaporation is performed on the etched first metal layer by electron beam evaporation to complete the preparation of the first metal layer; Step 5) If Figure 4 As shown, after the second metal evaporation is completed, other metal layers are evaporated; Step 6) If Figure 5 As shown, a lift-off process is used to peel off the photoresist layer and the metal deposited on the photoresist layer to form interdigital electrodes. Example
[0023] A novel interdigitated strip manufacturing process is carried out according to the following steps: Step 1) coating, exposing and developing photoresist on the substrate so that the photoresist shape presents a corresponding finger pattern; Step 2) If Figure 1 As shown, a first metal evaporation is performed on the photoresist and the substrate by an electron beam evaporation method; Step 3) If Figure 2 As shown, the metal and photoresist after the first evaporation are etched indiscriminately by an ion beam in the electron beam evaporation equipment, and the thickness of the ion beam etching is 30% of the thickness of the first evaporation metal; Step 4) If Figure 3 As shown, a second metal evaporation is performed on the etched first metal layer by electron beam evaporation to complete the preparation of the first metal layer; Step 5) If Figure 4 As shown, after the second metal evaporation is completed, other metal layers are evaporated; Step 6) If Figure 5 As shown, a lift-off process is used to peel off the photoresist layer and the metal deposited on the photoresist layer to form interdigital electrodes.
[0024] In the above three embodiments, the preparation of the first metal layer adopts ion beam etching to reduce the stress of the metal film layer. Ion etching is performed after the first growth of the metal layer is completed, which can reduce the defects of the metal film layer, improve the film density, increase the roughness of the metal film layer and reduce the stress. At the same time, the risk of film falling off is also greatly reduced.
[0025] However, for metals with relatively large stress, multiple electron beam evaporation + ion beam etching cycles can be performed according to the thickness of the film layer to ensure that the stress of the metal film layer is greatly reduced after each operation. As shown in the fourth embodiment. Example
[0026] A novel interdigitated strip manufacturing process is carried out according to the following steps: Step 1) coating, exposing and developing photoresist on the substrate so that the photoresist shape presents a corresponding finger pattern; Step 2) If Figure 1 As shown, a first metal evaporation is performed on the photoresist and the substrate by an electron beam evaporation method; Step 3) If Figure 2 As shown, the metal and photoresist after the first evaporation are etched indiscriminately by an ion beam in the electron beam evaporation equipment, and the thickness of the ion beam etching is 20% of the thickness of the first evaporation metal; Step 4) If Figure 3 As shown, a second metal evaporation is performed on the etched first metal layer by electron beam evaporation; Step 5) in an electron beam evaporation device, the metal and photoresist after the second evaporation are etched indiscriminately by an ion beam, and the thickness of the ion beam etching is 10% of the thickness of the second evaporation metal; Step 6) performing a third metal evaporation on the etched metal layer by electron beam evaporation; Step 7) After the third metal evaporation is completed, other metal layers are evaporated; Step 8) Using a lift-off process, the photoresist layer and the metal deposited on the photoresist layer are peeled off to form interdigital electrodes.
[0027] Through multiple electron beam evaporation + ion beam etching cycles, it is ensured that the stress of the metal film layer is greatly reduced after each operation. The product appearance yield, RF performance yield and reliability are improved. Through this operation, the present invention can effectively prepare high-performance, high-power and high-reliability filters. Example
[0028] A novel interdigitated strip manufacturing process is carried out according to the following steps: Step 1) coating, exposing and developing photoresist on the substrate so that the photoresist shape presents a corresponding finger pattern; Step 2) performing a first metal evaporation on the photoresist and the substrate by electron beam evaporation method; Step 3) etching the metal and photoresist after the first evaporation indiscriminately by ion beam in the electron beam evaporation equipment; Step 4) performing a second metal evaporation on the etched first metal layer by electron beam evaporation to complete the preparation of the first metal layer; Step 5) The second metal evaporation layer is again etched indiscriminately by ion beam in the electron beam evaporation equipment. After the etching is completed, the second metal layer is prepared on the first metal layer by alternating electron beam evaporation and ion beam etching. The stress of the first metal layer is greater than the stress of the second metal layer.
[0029] Step 6) After the second metal layer is evaporated, other metal layers are evaporated; Step 7) Using a lift-off process, the photoresist layer and the metal deposited on the photoresist layer are peeled off to form interdigitated electrodes.
[0030] This embodiment is different from the traditional electron beam evaporation process. By evaporating special metals in layers, the stress of the entire interdigitated metal film layer can be effectively reduced, and the risk of the metal film layer falling off after peeling can be reduced, ultimately improving the product appearance yield, RF performance yield and reliability. Using this solution for metal film layer evaporation, the interdigitated strip shedding rate is reduced from 30% to less than 5%.
[0031] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed by the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention shall be based on the protection scope of the claims.
Claims
1. A novel interdigitated strip manufacturing process, characterized in that: Follow these steps: Step 1) coating, exposing and developing photoresist on the substrate so that the photoresist shape presents a corresponding finger pattern; Step 2) performing a first metal evaporation on the photoresist and the substrate by electron beam evaporation method; Step 3) etching the metal and photoresist after the first evaporation indiscriminately by ion beam in the electron beam evaporation equipment; Step 4) performing a second metal evaporation on the etched first metal layer by electron beam evaporation to complete the preparation of the first metal layer; Step 5) After the second metal evaporation is completed, other metal layers are evaporated; Step 6) Using a lift-off process, the photoresist layer and the metal deposited on the photoresist layer are peeled off to form interdigitated electrodes.
2. A novel interdigitated strip manufacturing process according to claim 1, characterized in that: The thickness of the ion beam etching in step 3) is 10-30% of the thickness of the first evaporated metal.
3. A novel interdigitated strip manufacturing process according to claim 1, characterized in that: The number of cycles of the electron beam evaporation and ion beam etching alternating operations in step 3), step 4) and step 5) is 2 times, 3 times, or 4 times.
4. A novel interdigitated strip manufacturing process according to claim 1, characterized in that: After step 4), the second metal vapor deposition layer is again indiscriminately etched by ion beam in the electron beam evaporation equipment. After the etching is completed, the second metal layer is prepared on the first metal layer by alternating electron beam evaporation and ion beam etching.
5. A novel interdigitated strip manufacturing process according to claim 4, characterized in that: The stress of the first metal layer is greater than the stress of the second metal layer.