Surface acoustic wave filter chip containing copper film, preparation method of surface acoustic wave filter chip and filter

Abstract

The invention discloses a surface acoustic wave filter chip containing a copper film, a preparation method of the surface acoustic wave filter chip and a filter. The preparation method comprises the following steps: carrying out glue uniformizing, photoetching and developing operations on a substrate layer; evaporating an electrode layer containing a copper film layer on the substrate layer, and then performing stripping operation to pattern the electrode layer on the upper surface of the substrate layer; carrying out glue uniformizing, photoetching and developing operations on the substrate layer again so as to divide the electrode layer into an exposed non-electrode region and two electrode regions covered and protected by a second photoresist layer; sputtering operation is carried out on the substrate layer, then stripping operation is carried out to expose the electrode area, and meanwhile, a first protection layer is formed in the non-electrode area; carrying out glue uniformizing, photoetching and developing operation on the substrate layer again so as to cover and protect the non-electrode region by the third photoresist layer; evaporating a second protective layer in the electrode area in sequence, and then performing stripping operation on the non-electrode area; and welding a silicon-aluminum wire at the upper end of the second protective layer. The preparation method is simple and convenient in processing flow and high in processing precision.

Description

Technical Field

[0001] The invention belongs to the technical field of filter chips, and in particular relates to a copper-film surface acoustic wave filter chip and a preparation method and a filter. Background Art

[0002] Aluminum is a commonly used electrode material for surface acoustic wave filters. However, the relative bandwidth that surface acoustic wave filters prepared with aluminum electrodes can achieve is relatively small, and it is gradually difficult to meet the requirements of the communication field for large bandwidth. Surface acoustic wave filters prepared with copper film as electrodes can achieve a larger relative bandwidth, and they have lower resistivity and parasitic capacitance, which helps to reduce circuit power consumption and delay, reduce signal crosstalk, and at the same time, copper materials are more resistant to electromigration effects. With the increase in the operating frequency and power of surface acoustic wave filters, copper materials have become a better choice. At present, in order to prevent the oxidation of copper films, there is a structure in which copper films are plated inside the etched silicon oxide channel, and the surface is protected by aluminum films. However, the preparation of this structure requires high overlay accuracy, cumbersome operation, and complex etching process. In addition, the adhesion of aluminum films on the surface of copper films is poor, and the film layer is prone to fall off. Summary of the invention

[0003] In order to solve the above technical problems, one of the objectives of the present invention is to provide a method for preparing a copper-containing membrane surface acoustic wave filter chip which is convenient and easy to prepare, has a simple process, and has high operating precision.

[0004] In order to achieve the above object, the technical solution of the present invention is as follows: A method for preparing a copper film surface acoustic wave filter chip comprises the following steps:

[0005] Step 1: performing photoresist, photolithography and development operations on the base layer to transfer the desired pattern to the base layer in the form of a first photoresist layer;

[0006] Step 2: vapor-depositing an electrode layer containing a copper film layer on the base layer treated in step 1, and then performing a stripping operation to pattern the electrode layer on the upper surface of the base layer;

[0007] Step 3: performing photoresist, photolithography and development operations again on the substrate layer processed in step 2 to divide the electrode layer into an exposed non-electrode area and two electrode areas covered and protected by a second photoresist layer;

[0008] Step 4: performing a sputtering operation on the substrate layer processed in step 3, and then performing a stripping operation to expose the electrode area, and forming a first protective layer in the non-electrode area;

[0009] Step 5: performing photoresist, photolithography and development operations again on the base layer processed in step 4, so that the non-electrode area is covered and protected by the third photoresist layer;

[0010] Step 6: After the treatment in step 5, the electrode area is first evaporated with a second protective layer, and then the non-electrode area is stripped;

[0011] Step 7: The preparation of the copper-containing membrane surface acoustic wave filter chip is completed by welding the silicon aluminum wire on the upper end of the second protective layer. In this way, the entire copper-containing membrane surface acoustic wave filter chip can be stacked layer by layer by evaporation during preparation, and during evaporation, photoresist is used to cover and protect the area that does not need evaporation. After evaporation, the photoresist layer and the evaporation layer attached thereto can be peeled off. The processing flow is simple, the processing precision is high, and the stability is good.

[0012] In the above technical solution, the thickness of the first protective layer is 15-25 nm.

[0013] The beneficial effects of the above technical solution are: moderate thickness and good protective effect.

[0014] In the above technical solution, the second protective layer includes a third titanium film layer and an aluminum film layer which are sequentially evaporated from bottom to top.

[0015] The beneficial effect of the above technical solution is that the third titanium film layer provides mutual bonding performance between the aluminum film layer and the electrode layer.

[0016] The thickness of the third titanium film layer in the above technical solution is 1-10 nm.

[0017] The beneficial effect of the above technical solution is that its thickness is moderate.

[0018] The thickness of the aluminum film layer in the above technical solution is 1000-1500nm.

[0019] The beneficial effect of the above technical solution is that by thickening the aluminum film layer, it is convenient for subsequent welding of silicon aluminum wire.

[0020] The electrode layer in the above technical solution includes a first titanium film layer, a copper film layer and a second titanium film layer which are sequentially deposited from bottom to top.

[0021] The beneficial effect of the above technical solution is that the first titanium film layer, the copper film layer and the second titanium film layer form a titanium-copper-titanium sandwich structure, so that the copper film layer is wrapped between the titanium film layers, which can prevent the copper film layer from being oxidized.

[0022] The raw material for sputtering in the steps described in the above technical solution is SiO2, and the first protective layer is a SiO2 film layer.

[0023] The beneficial effect of the above technical solution is that the first protective layer completely covers the copper film layer in the non-electrode area to prevent the copper film layer from being oxidized.

[0024] The thickness of the electrode layer in the above technical solution is 10-1000nm.

[0025] The beneficial effect of the above technical solution is that the thickness of the electrode layer can be flexibly set as needed.

[0026] The second object of the present invention is to provide a copper-containing membrane surface acoustic wave filter chip with simple structure, good performance and good stability between membrane layers.

[0027] In order to achieve the above object, the technical solution of the present invention is as follows: a copper film surface acoustic wave filter chip is prepared by the preparation method as described above.

[0028] The beneficial effects of the above technical solution are: its structure is simple, its stability is good, and its performance is good.

[0029] A third object of the present invention is to provide a filter with simple structure and good performance.

[0030] In order to achieve the above object, the technical solution of the present invention is as follows: a filter comprises the copper-containing film surface acoustic wave filter chip as described above.

[0031] The beneficial effects of the above technical solution are: good stability and good performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is a cross-sectional view after the first photoresist layer is evenly applied on the base layer in step 1 of the embodiment of the present invention;

[0033] Figure 2 It is a cross-sectional view of the first photoresist layer on the base layer after being subjected to photolithography and development in step 1 of the embodiment of the present invention;

[0034] Figure 3 It is a cross-sectional view after the electrode layer is evaporated on the substrate layer in step 2 of the embodiment of the present invention;

[0035] Figure 4 It is a cross-sectional view after the first photoresist layer remaining on the base layer is stripped off in step 2 of the embodiment of the present invention;

[0036] Figure 5 It is a cross-sectional view after the second photoresist layer is evenly applied on the base layer in step 3 of the embodiment of the present invention;

[0037] Figure 6 It is a cross-sectional view of the second photoresist layer on the base layer after being subjected to photolithography and development in step 3 of the embodiment of the present invention;

[0038] Figure 7 It is a cross-sectional view after the first protective layer is sputtered on the base layer in step 4 of the embodiment of the present invention;

[0039] Figure 8 It is a cross-sectional view of the second photoresist layer remaining on the base layer after being stripped in step 4 of the embodiment of the present invention;

[0040] Fig. 9 It is a cross-sectional view after the third photoresist layer is evenly applied on the base layer in step 5 of the embodiment of the present invention;

[0041] Fig.10 is a cross-sectional view of the third photoresist layer on the base layer after being subjected to photolithography and development processing in step 5 of the embodiment of the present invention;

[0042] Fig.11 It is a cross-sectional view after the second protective layer is evaporated on the base layer and the remaining third photoresist layer is peeled off in step 6 of the embodiment of the present invention;

[0043] Fig.12 This is a cross-sectional view of the electrode region after silicon aluminum wire is welded on the second protective layer in step 7 of the embodiment of the present invention.

[0044] In the figure: 1, base layer; 2, electrode layer; 21, first titanium film layer; 22, copper film layer; 23, second titanium film layer; 3, first protective layer; 4, second protective layer; 41, third titanium film layer; 42, aluminum film layer; 5, silicon aluminum wire; 6a, first photoresist layer; 6b, second photoresist layer; 6c, third photoresist layer; 7, non-electrode area; 8, electrode area. DETAILED DESCRIPTION

[0045] The principles and features of the present invention are described below in conjunction with the accompanying drawings. The examples given are only used to explain the present invention and are not used to limit the scope of the present invention. The present invention is described in more detail by way of example with reference to the accompanying drawings in the following paragraphs. According to the following description and claims, the advantages and features of the present invention will be more clearly described. It should be noted that the drawings are all in a very simplified form and are not in precise proportions, and are only used to facilitate and clearly assist in explaining the purpose of the embodiments of the present invention.

[0046] Example 1

[0047] like Figure 1-Figure 12 As shown, this embodiment provides a method for preparing a copper film surface acoustic wave filter chip, comprising the following steps:

[0048] Step 1: performing photoresist, photolithography and development operations on the base layer 1 to transfer the desired pattern to the base layer 1 in the form of a first photoresist layer 6a;

[0049] Step 2: The electrode layer 2 containing the copper film layer 22 is evaporated on the base layer 1 treated in step 1, and then a stripping operation is performed (this stripping operation is to strip the area where the first photoresist layer remains on the base layer, and the channel is formed in this area later) to pattern the electrode layer 2 on the upper surface of the base layer 1;

[0050] Step 3: performing photoresist, photolithography and development operations again on the substrate layer 1 processed in step 2 to divide the electrode layer 2 into an exposed non-electrode area 7 and two electrode areas 8 covered and protected by the second photoresist layer 6b;

[0051] Step 4: performing a sputtering operation on the base layer 1 processed in step 3, and then performing a stripping operation (this stripping operation is to strip the area where the second photoresist layer remains on the base layer) to expose the electrode area 8, and forming a first protective layer 3 on the non-electrode area 7;

[0052] Step 5: performing photoresist, photolithography and development operations again on the base layer 1 processed in step 4, so that the non-electrode area 7 is covered and protected by the third photoresist layer 6c;

[0053] Step 6: The electrode area after the treatment in step 5 is successively evaporated with a second protective layer 4, and then the non-electrode area 7 is stripped (this stripping operation is to strip the area where the third photoresist layer remains on the base layer);

[0054] Step 7: The preparation of the copper-containing film surface acoustic wave filter chip is completed by welding the silicon aluminum wire 5 on the upper end of the second protective layer 4. In this way, the entire copper-containing film surface acoustic wave filter chip can be stacked layer by layer by evaporation during preparation, and during evaporation, photoresist is used to cover and protect the area that does not need evaporation. After evaporation, the photoresist layer and the evaporation layer attached thereto can be peeled off. The processing flow is simple, the processing accuracy is high, and the stability is good.

[0055] In the above technical solution, the thickness of the first protective layer 3 is 15-25nm (it can be any value among 15nm, 16nm, 17nm, 18nm, 19nm, 20nm, 21nm, 22nm, 23nm, 24nm and 24nm, or the corresponding range between any two values), which is moderate in thickness and has good protective effect.

[0056] In the above technical solution, the second protective layer 4 includes a third titanium film layer 41 and an aluminum film layer 42 which are sequentially evaporated from bottom to top, so that the third titanium film layer provides mutual bonding performance between the aluminum film layer and the electrode layer.

[0057] The thickness of the third titanium film layer 41 described in the above technical solution is 1-10nm (it can be any value among 1nm, 16nm, 2nm, 3nm, 4nm, 5nm, 6nm, 7nm, 8nm, 9nm and 10nm or the corresponding range between any two values), and its thickness is moderate.

[0058] The thickness of the aluminum film layer 42 in the above technical solution is 1000-1500nm (it can be any value among 1000nm, 1100nm, 1200nm, 1300nm, 1400nm and 1500nm or the corresponding range between any two values). By thickening the aluminum film layer, it is beneficial to the subsequent welding operation of silicon aluminum wire.

[0059] The electrode layer 2 described in the above technical solution includes a first titanium film layer 21, a copper film layer 22 and a second titanium film layer 23 evaporated from bottom to top in sequence, so that the first titanium film layer, the copper film layer and the second titanium film layer form a titanium-copper-titanium sandwich structure, so that the copper film layer is wrapped between the titanium film layers, which can prevent the copper film layer from being oxidized.

[0060] The raw material sputtered in step 4 of the above technical solution is SiO2, and the first protective layer 3 is a SiO2 film layer, so that the first protective layer completely covers the copper film layer in the non-electrode area to prevent the copper film layer from being oxidized.

[0061] The thickness of the electrode layer 2 in the above technical solution is 10-1000nm (it can be any value among 10nm, 100nm, 200nm, 300nm, 400nm, 500nm, 600nm, 700nm, 800nm, 900nm and 1000nm or the corresponding range between any two values), so that the thickness of the electrode layer can be flexibly set as needed.

[0062] The copper film surface acoustic wave filter chip prepared in this embodiment is characterized in that its electrode layer adopts a titanium-copper-titanium sandwich structure. At this time, the copper film layer is wrapped by two titanium film layers, so that the copper film layer is not easily oxidized and corroded during use, and the non-electrode area of ​​the electrode layer is fully covered with a first protective layer, which can further protect the copper film layer from oxidation. In addition, the electrode area is thickened with an aluminum-titanium structure, which is convenient for subsequent silicon-aluminum wire welding operations.

[0063] The process flow of the copper film surface acoustic wave filter chip provided in this embodiment is simple, which reduces the requirements for overlay accuracy. It also improves the protection effect of the copper film layer, prevents the copper film layer from oxidizing during use or subsequent heating, maintains the stability of the device performance, and improves the reliability and service life of the product.

[0064] Example 2

[0065] This embodiment provides a copper-containing film surface acoustic wave filter chip, which is manufactured by the manufacturing method described in Example 1 and has a simple structure, good stability, and good performance.

[0066] Example 3

[0067] This embodiment provides a filter, including the copper-containing film surface acoustic wave filter chip as described in Embodiment 2, which has good stability and performance.

[0068] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Any ordinary technician in the industry can smoothly implement the present invention as shown in the drawings and described above. However, any equivalent changes, modifications and evolutions made by technicians familiar with the profession without departing from the scope of the technical solution of the present invention using the technical content disclosed above are all equivalent embodiments of the present invention. At the same time, any equivalent changes, modifications and evolutions made to the above embodiments based on the essential technology of the present invention are still within the protection scope of the technical solution of the present invention.

Claims

1. A method for preparing a copper film surface acoustic wave filter chip, characterized in that: The steps include: Step 1: performing photoresist, photolithography and development operations on the base layer (1) to transfer the desired pattern to the base layer (1) in the form of a first photoresist layer (6a); Step 2: vapor-depositing an electrode layer (2) containing a copper film layer (22) on the base layer (1) treated in step 1, and then performing a peeling operation to pattern the electrode layer (2) on the upper surface of the base layer (1); Step 3: performing photoresist, photolithography and development operations again on the substrate layer (1) processed in step 2 to divide the electrode layer (2) into an exposed non-electrode area (7) and two electrode areas (8) covered and protected by a second photoresist layer (6b); Step 4: performing a sputtering operation on the base layer (1) processed in step 3, and then performing a stripping operation to expose the electrode area (8) and simultaneously forming a first protective layer (3) on the non-electrode area (7); Step 5: performing photoresist, photolithography and development operations again on the base layer (1) processed in step 4, so that the non-electrode area (7) is covered and protected by the third photoresist layer (6c); Step 6: After the treatment in step 5, the electrode area is first evaporated with a second protective layer (4), and then the non-electrode area (7) is stripped; Step 7: Welding the silicon aluminum wire (5) on the upper end of the second protective layer (4) completes the preparation of the copper film surface acoustic wave filter chip.

2. The method for preparing a copper-containing film surface acoustic wave filter chip according to claim 1, characterized in that: The thickness of the first protective layer (3) is 15-25 nm.

3. The method for preparing a copper-containing film surface acoustic wave filter chip according to claim 1, characterized in that: The second protective layer (4) comprises a third titanium film layer (41) and an aluminum film layer (42) which are sequentially evaporated from bottom to top.

4. The method for preparing a copper-containing film surface acoustic wave filter chip according to claim 3, characterized in that: The thickness of the third titanium film layer (41) is 1-10 nm.

5. The method for preparing a copper-containing film surface acoustic wave filter chip according to claim 3, characterized in that: The thickness of the aluminum film layer (42) is 1000-1500 nm.

6. The method for preparing a copper-containing film surface acoustic wave filter chip according to claim 1, characterized in that: The electrode layer (2) comprises a first titanium film layer (21), a copper film layer (22) and a second titanium film layer (23) which are sequentially evaporated from bottom to top.

7. The method for preparing a copper-containing film surface acoustic wave filter chip according to claim 1, characterized in that: The raw material for sputtering in step 4 is SiO2, and the first protective layer (3) is a SiO2 film layer.

8. The method for preparing a copper-containing film surface acoustic wave filter chip according to claim 1, characterized in that: The thickness of the electrode layer (2) is 10-1000 nm.

9. A copper film surface acoustic wave filter chip, characterized in that: The method is prepared according to any one of claims 1 to 8.

10. A filter, characterized in that: It comprises the copper-containing film surface acoustic wave filter chip as claimed in claim 9.

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