Resonator packaging method
By forming a bonding and curing method of the adhesive layer and packaging film on the surface of the FBAR chip, the existing metal bonding packaging problems are solved, and non-metallic and low-cost FBAR packaging is realized, which expands the chip performance design space.
Patent Information
- Application Number
- CN202411845317.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-13
- Publication Date
- 2025-03-25
AI Technical Summary
The existing FBAR packaging methods use metal bonding, resulting in high costs and electromagnetic parasitics, limiting the performance design space of FBAR chips.
Using a non-metallic material packaging method, a sealing cover is formed by applying glue on the surface of the resonator and exposing and developing, and then covering the packaging film and heating it to bond and cure it to form a sealing cover plate.
It realizes non-metallic, low-cost FBAR packaging, reducing material costs and process complexity, while avoiding electromagnetic parasites, and expanding the performance design space of FBAR chips.
Smart Images
Figure CN119696532A_ABST
Abstract
Description
Technical Field
[0001] The present application relates to the field of resonator manufacturing, and in particular to a packaging method for a resonator. Background Art
[0002] FBAR (Film Bulk Acoustic Resonator) has the characteristics of small size, suitability for high frequencies, and integration with IC (Integrated Circuit) technology. It has a broad market space in application scenarios of sub6G and above.
[0003] In the prior art, FBAR packaging generally uses metal bonding between the cover plate and the FBAR chip. This method has excellent mechanical strength and sealing properties, but is costly. In addition, the metal bonding and sealing metal ring will cause electromagnetic parasitics in the FBAR, thereby limiting the performance space of the FBAR chip design.
[0004] Therefore, how to realize a non-metallic, low-cost FBAR packaging method has become an urgent problem to be solved in this field. Summary of the invention
[0005] The present application provides a packaging method for a resonator, the purpose of which is to achieve non-metallic, low-cost FBAR packaging.
[0006] In order to achieve the above objectives, this application provides the following technical solutions:
[0007] A method for packaging a resonator, comprising:
[0008] After the manufacturing process of the resonator reaches the target step, the upper surface is coated with glue using the target compound to obtain a glue layer, and the key area of the glue layer is exposed and developed; the target step includes: etching a lower cavity in the substrate, and filling the lower cavity with silicon material to obtain a sacrificial layer; the key area includes the area corresponding to the lower cavity, and the areas corresponding to the release hole, the test electrode, and the pad of the resonator;
[0009] After releasing the sacrificial layer, firstly baking the adhesive layer, and then testing and adjusting the frequency of the resonator;
[0010] Using a target film material, coating the outer surface of the adhesive layer to obtain a packaging film, and heating the packaging film so that the packaging film and the adhesive layer are bonded and cured to form a sealing cover plate of the resonator;
[0011] The solder balls of the resonator are manufactured to obtain the packaging structure of the resonator.
[0012] Optionally, the types of the target compound include polyimide and benzocyclobutene.
[0013] Optionally, the target film material types include DAF film and Toray film.
[0014] Optionally, making solder balls of the resonator to obtain a packaging structure of the resonator includes:
[0015] Using laser to eliminate the area of the packaging film corresponding to the pad, so that the pad is exposed;
[0016] A solder ball is made on the exposed solder pad to obtain the packaging structure of the resonator.
[0017] Optionally, the process of making solder balls on the exposed solder pads includes one of the following:
[0018] Electroplating the exposed pads with a dry film material to generate solder balls on the pads;
[0019] The solder paste is printed on the exposed solder pad by using a steel mesh, so that solder balls are generated on the solder pad.
[0020] Optionally, making solder balls of the resonator to obtain a packaging structure of the resonator includes:
[0021] Thinning the substrate to obtain a thinned substrate;
[0022] Etching a hole connected to the electrode of the resonator on the back side of the thinned substrate so that the electrode is exposed to the outside;
[0023] A solder ball is made on the electrode exposed to the outside to obtain the packaging structure of the resonator.
[0024] Optionally, making solder balls of the resonator to obtain a packaging structure of the resonator includes:
[0025] First, the outer surface of the sealing film is coated with a target protective material to generate a protective film of the sealing cover plate, and then the solder balls of the resonator are made to obtain the packaging structure of the resonator.
[0026] Optionally, types of the target protective material include resin and inorganic matter.
[0027] Optionally, the method further includes:
[0028] Before the target compound is used to coat the upper surface with glue, the aluminum nitride in the edge sealing area of the substrate is etched in advance to combine the substrate with the glue layer.
[0029] Optionally, a target area where the substrate is combined with the adhesive layer is etched into an anti-stripping structure.
[0030] The technical solution provided by the present application is that after the manufacturing process of the resonator reaches the target step, the upper surface is coated with a target compound to obtain a glue layer, and the key areas of the glue layer are exposed and developed. After releasing the sacrificial layer, the glue layer is first baked, and then the frequency of the resonator is tested and adjusted. The outer surface of the glue layer is coated with a target film material to obtain a packaging film, and the packaging film is heated so that the packaging film and the glue layer are bonded and cured to form a sealing cover plate of the resonator. The solder balls of the resonator are made to obtain the packaging structure of the resonator. The present application uses the glue layer as a surface support structure, and the packaging film as a surface packaging film to form a sealing cover plate of the resonator. The material cost is low and the process is relatively simple, thereby realizing non-metallic, low-cost FBAR packaging. BRIEF DESCRIPTION OF THE DRAWINGS
[0031] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.
[0032] Figure 1 A schematic diagram of a process of packaging a resonator provided in an embodiment of the present application;
[0033] Figure 2 A packaging process diagram of a resonator provided in an embodiment of the present application;
[0034] Figure 3 A packaging process diagram of a resonator provided in an embodiment of the present application;
[0035] Figure 4 A packaging process diagram of a resonator provided in an embodiment of the present application;
[0036] Figure 5 A packaging process diagram of a resonator provided in an embodiment of the present application;
[0037] Figure 6 A packaging process diagram of a resonator provided in an embodiment of the present application;
[0038] Figure 7 A packaging process diagram of a resonator provided in an embodiment of the present application;
[0039] Figure 8 A packaging process diagram of a resonator provided in an embodiment of the present application;
[0040] Fig. 9 A packaging process diagram of a resonator provided in an embodiment of the present application;
[0041] Fig.10 A packaging process diagram of a resonator provided in an embodiment of the present application;
[0042] Fig.11 A packaging process diagram of a resonator provided in an embodiment of the present application. DETAILED DESCRIPTION
[0043] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.
[0044] In this application, relational terms such as first and second, etc. are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. The terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of more restrictions, the elements defined by the sentence "comprise one..." do not exclude the existence of other identical elements in the process, method, article or device including the elements.
[0045] like Figure 1 As shown, it is a schematic diagram of a process flow of a resonator packaging method provided in an embodiment of the present application. The process diagram corresponding to each step can be found in Figure 2-Figure 11 As shown, it can be applied to FBAR, including the steps shown below.
[0046] S101: Figure 2-Figure 3 As shown, after the manufacturing process of the resonator reaches the target step, the upper surface is coated with a target compound to obtain a glue layer, and the key area of the glue layer is exposed and developed.
[0047] The target steps include: Figure 2 As shown, a lower cavity is etched in the substrate, and the lower cavity is filled with silicon material to obtain a sacrificial layer. In addition, the upper surface is coated with a target compound to obtain a glue layer, and the key area of the glue layer is exposed and developed. The final glue layer is as shown in FIG. Figure 3In a possible implementation, the key area includes at least an area corresponding to the lower cavity, and areas corresponding to the release hole of the resonator, a test electrode (used to contact a test probe to measure electrical performance), and a pad (used to perform a bumping process).
[0048] In some examples, the upper surface can be understood as: the outer surface of the structure (usually including the bottom electrode, the piezoelectric layer, the top electrode, and the passivation layer) located directly above the substrate.
[0049] Generally speaking, FBAR is mainly a sandwich structure consisting of two layers of metal electrodes (including bottom electrode and top electrode) and piezoelectric material (piezoelectric layer) in the middle. When radio frequency voltage is applied to the two electrodes, the piezoelectric material converts part of the electrical energy into bulk acoustic waves that propagate along the thickness direction of the film through the inverse piezoelectric effect, and reflects back and forth between the two electrodes. When the thickness of the piezoelectric layer is exactly half the wavelength of the bulk acoustic wave or an odd multiple of half the wavelength, a standing wave will be formed and oscillation will occur. Depending on the structure, FBAR can be classified into silicon substrate reverse etched type FBAR and air gap type FBAR.
[0050] In some examples, the type of silicon material may be phosphosilicate glass, that is, the lower cavity may be filled with phosphosilicate glass to obtain a sacrificial layer.
[0051] It should be noted that the size of the lower cavity can be set by the technicians according to the actual situation, and the upper surface is flat and smooth. If the upper surface is not flat and smooth, it is necessary to polish the upper surface to make it flat and smooth.
[0052] In a possible implementation, the manufacturing process of FBAR includes: etching a lower cavity on the substrate and filling the lower cavity with phosphosilicate glass as a sacrificial layer; secondly, chemically mechanically polishing the upper surface to remove excess sacrificial layer and keep the upper surface smooth; then depositing a seed layer and a bottom electrode in sequence and patterning them; then growing a piezoelectric layer on the bottom electrode by magnetron sputtering; then depositing and patterning a top electrode; then leading out the bottom electrode through an etched hole; in order to metallize the electrode, first depositing a layer of gold and then stripping off excess gold; finally, releasing the sacrificial layer by wet etching.
[0053] It should be noted that the area corresponding to the lower cavity can be understood as the area corresponding to the projection of the lower cavity onto the glue layer. The area corresponding to the release hole can be understood as the area corresponding to the projection of the release hole onto the glue layer. The area corresponding to the test electrode can be understood as the area corresponding to the projection of the test electrode onto the glue layer. The area corresponding to the pad can be understood as the area corresponding to the projection of the pad onto the glue layer.
[0054] Generally speaking, the key areas of the glue layer are exposed and developed mainly to prevent the lower cavity and the release holes, test electrodes and pads of the resonator from being covered by the glue layer.
[0055] It should be noted that the target compound is usually a compound with a low water absorption rate so that the waterproof property of the adhesive layer is improved. Optionally, the types of the target compound are polyimide (PI) and benzocyclobutene (BCB).
[0056] In some examples, PI is a high-performance electronic packaging material with excellent thermal conductivity, electrical insulation and mechanical strength, and is commonly used for packaging electronic components.
[0057] In some examples, BCB is a high-performance material with low dielectric constant, low water absorption, good thermal stability and chemical stability, and therefore is widely used in the field of electronic packaging.
[0058] It is understandable that the adhesive layer obtained by coating the upper surface with the target compound can serve as a surface support structure to prevent the outside from directly contacting the upper surface.
[0059] In some examples, exposure is used to project the key area onto the glue layer to obtain a corresponding exposure area. In addition, development is used to remove the glue layer in the exposure area.
[0060] S102: Figure 4 As shown, after releasing the sacrificial layer, the glue layer is baked first, and then the frequency of the resonator is tested and adjusted.
[0061] Among them, the process of releasing the sacrificial layer and the prerequisite process steps can be seen in the FBAR manufacturing process flow. Since the embodiment of the present application mainly describes the FBAR packaging process, the process of releasing the sacrificial layer and the prerequisite process steps will not be further described here.
[0062] It should be noted that baking the glue layer can remove moisture, solvents and small organic molecules in the colloid, thereby preventing the frequency test and adjustment of the resonator from being interfered by moisture, solvents and small organic molecules.
[0063] In some examples, frequency testing and trimming of the resonator (which can be achieved by a trim process) is a conventional testing method used after the FBAR manufacturing process is completed to verify the performance of the resonator, which will not be described in detail here.
[0064] S103: Figure 5 As shown, the outer surface of the adhesive layer is coated with a target film material to obtain a packaging film, and the packaging film is heated so that the packaging film and the adhesive layer are bonded and cured to form a sealing cover plate of the resonator.
[0065] The adhesive layer is used as the surface support structure of the sealing cover plate, and the packaging film is used as the surface packaging film of the sealing cover plate, thereby ensuring the sealing performance of the sealing cover plate.
[0066] Optionally, the types of target membrane materials include DAF membrane and Toray membrane.
[0067] In some examples, DAF film is a high-performance adhesive film, the full name of which is Die Attach Film, which is widely used in the field of semiconductor packaging, mainly for the connection between chips and substrates. DAF film has excellent bonding and thermal conductivity, and can remain stable in high temperature environments, thus providing reliable mechanical connection and thermal management for chips.
[0068] In some examples, the Toray film is a high-performance adhesive film disclosed in the prior art.
[0069] It should be noted that heating the packaging film can soften the colloid of the packaging film so that it can be adhered and cured, thereby making the packaging film adhere to the adhesive layer. Specifically, the heating method of the packaging film includes but is not limited to electromagnetic heating, infrared heating and the like.
[0070] S104: Make solder balls of the resonator to obtain a packaging structure of the resonator.
[0071] Among them, the solder ball is a very important component in the flip-chip process. Its main functions are: 1. Conductive function, used to connect the FBAR pad and the package substrate, so as to realize the signal transmission between the FBAR and the outside; 2. Heat dissipation function, which conducts the heat generated during the operation of the FBAR to the substrate; 3. Support function.
[0072] It should be emphasized that after making the solder balls of the resonator, a series of process steps (such as substrate thinning, cutting, conventional substrate packaging, etc.) are required to obtain the packaging structure of the resonator. The subsequent process steps are conventional means and will not be elaborated here.
[0073] Optionally, the solder balls of the resonator are made to obtain the process corresponding to the packaging structure of the resonator. Figure 6-Figure 7 As shown, a laser is used to eliminate the area corresponding to the pad in the packaging film so that the pad is exposed, and solder balls are made on the exposed pad to obtain a packaging structure of the resonator.
[0074] It should be noted that using laser to eliminate the colloid in the area where the pad is projected upward to the packaging film can expose the pad outside the sealing cover of the resonator, so as to make solder balls on the pad to obtain the packaging structure of the resonator.
[0075] Optionally, the process of making solder balls on the exposed solder pads to obtain the packaging structure of the resonator includes one of the following: electroplating the exposed solder pads with a dry film material to generate solder balls on the solder pads; printing solder paste on the exposed solder pads with a steel mesh to generate solder balls on the solder pads.
[0076] It can be understood that electroplating the exposed pads with dry film materials can be regarded as making solder balls using electroplating technology, and printing solder paste on the exposed pads with steel mesh can be regarded as making solder balls using solder paste printing technology.
[0077] In addition, in addition to making solder balls on the solder pads of the resonator, solder balls can also be made on the electrodes of the resonator to avoid damage to the packaging film.
[0078] Optionally, the solder balls of the resonator are made to obtain the process corresponding to the packaging structure of the resonator. Figure 8 As shown, the substrate is thinned to obtain a thinned substrate, a hole connecting the electrode of the resonator is etched on the back side of the thinned substrate so that the electrode is exposed, and a solder ball is made on the exposed electrode to obtain a packaging structure of the resonator.
[0079] In some examples, the size of the thinned substrate may be set by a technician based on actual conditions to ensure that the thinned substrate does not affect the performance of the resonator.
[0080] Furthermore, in order to enhance the protection of the sealing cover of the resonator, a protective layer may be added to the outer surface of the packaging film after the packaging film is made but before the solder balls are made. Fig. 9 As shown, the outer surface of the sealing film is first coated with a target protective material to generate a protective film for the sealing cover plate, and then solder balls of the resonator are made to obtain a packaging structure of the resonator.
[0081] Optionally, the types of target protective materials include resins (such as PI) and inorganic substances (such as silica).
[0082] Further, in order to improve the sealing effect of the resonator, optionally, see Fig.10 As shown, before the target compound is used to coat the upper surface, the aluminum nitride in the edge sealing area of the substrate can be etched in advance to combine the substrate with the glue layer.
[0083] It should be noted that the combination of aluminum nitride and the substrate will cause poor bonding between the sealing cover and the substrate, affecting the reliability of the resonator. Specifically, aluminum nitride will react with water. If aluminum nitride reacts with water to generate other substances during the subsequent aging process of the resonator, stratification will occur due to decreased bonding strength (for example, a gap will form between the sealing cover and the substrate, i.e., debonding will occur).
[0084] It is understandable that removing the aluminum nitride allows the glue layer to directly contact the substrate, thereby enhancing the bonding force between the substrate and the sealing cover plate.
[0085] Further, in order to avoid the problem of delamination due to the decrease of bonding force during the aging process of the resonator, optionally, see Fig.11 As shown, the target area where the substrate and the glue layer are combined is etched into an anti-stripping structure, which can effectively avoid the aging problem of aluminum nitride hydrolysis and stratification.
[0086] In a possible implementation, the cross-sectional shape of the anti-detachment structure can be understood as a wavy inverted trapezoid. The anti-detachment structure with this cross-sectional shape can promote the bonding between the adhesive layer and the substrate, so that the bonding force is effectively enhanced, thereby avoiding the occurrence of debonding.
[0087] In the steps S101-S104 above, the adhesive layer is used as a surface support structure, and the packaging film is used as a surface packaging film to form a sealing cover plate of the resonator. The material cost is low and the process is relatively simple, thereby realizing non-metallic, low-cost FBAR packaging.
[0088] Although several specific implementation details are included in the above discussion, these should not be interpreted as limiting the scope of the present application. Certain features described in the context of a separate embodiment can also be implemented in a single embodiment in combination. On the contrary, the various features described in the context of a single embodiment can also be implemented in multiple embodiments individually or in any suitable sub-combination.
[0089] The above description is only a preferred embodiment of the present application and an explanation of the technical principles used. Those skilled in the art should understand that the scope of disclosure involved in the present application is not limited to the technical solution formed by a specific combination of the above technical features, but should also cover other technical solutions formed by any combination of the above technical features or their equivalent features without departing from the above disclosed concept. For example, the above features are replaced with the technical features with similar functions disclosed in this application (but not limited to) by each other to form a technical solution.
Claims
1. A method for packaging a resonator, characterized in that: include: After the manufacturing process of the resonator reaches the target step, the upper surface is coated with a target compound to obtain a glue layer, and a key area of the glue layer is exposed and developed; The target step includes: etching a lower cavity in the substrate, and filling the lower cavity with silicon material to obtain a sacrificial layer; the key area includes an area corresponding to the lower cavity, and areas corresponding to the release hole, the test electrode, and the pad of the resonator; After releasing the sacrificial layer, firstly baking the adhesive layer, and then testing and adjusting the frequency of the resonator; Using a target film material, coating the outer surface of the adhesive layer to obtain a packaging film, and heating the packaging film so that the packaging film and the adhesive layer are bonded and cured to form a sealing cover plate of the resonator; The solder balls of the resonator are manufactured to obtain the packaging structure of the resonator.
2. The method according to claim 1, characterized in that The types of target compounds include polyimide and benzocyclobutene.
3. The method according to claim 1, characterized in that The types of target film materials include DAF film and Toray film.
4. The method according to claim 1, characterized in that: Making solder balls of the resonator to obtain a packaging structure of the resonator includes: Using laser to eliminate the area of the packaging film corresponding to the pad, so that the pad is exposed; A solder ball is made on the exposed solder pad to obtain the packaging structure of the resonator.
5. The method according to claim 4, characterized in that The process of forming solder balls on the exposed solder pads includes one of the following steps: Electroplating the exposed pads with a dry film material to generate solder balls on the pads; The solder paste is printed on the exposed solder pad by using a steel mesh, so that solder balls are generated on the solder pad.
6. The method according to claim 1, characterized in that Making solder balls of the resonator to obtain a packaging structure of the resonator includes: Thinning the substrate to obtain a thinned substrate; Etching a hole connected to the electrode of the resonator on the back side of the thinned substrate so that the electrode is exposed to the outside; A solder ball is made on the electrode exposed to the outside to obtain the packaging structure of the resonator.
7. The method according to claim 1, characterized in that Making solder balls of the resonator to obtain a packaging structure of the resonator includes: First, the outer surface of the sealing film is coated with a target protective material to generate a protective film of the sealing cover plate, and then the solder balls of the resonator are made to obtain the packaging structure of the resonator.
8. The method according to claim 7, characterized in that The types of the target protective material include resins and inorganic substances.
9. The method according to claim 1, characterized in that: The method further comprises: Before the target compound is used to coat the upper surface with glue, the aluminum nitride in the edge sealing area of the substrate is etched in advance to combine the substrate with the glue layer.
10. The method according to claim 9, characterized in that The target area where the substrate and the adhesive layer are combined is etched into an anti-stripping structure.