A MEMS package structure

Abstract

The utility model discloses a kind of MEMS packaging structures, comprising: MEMS device wafer and packaging cover plate, device wafer is provided with MEMS device structure and two groups of lead-out pads, MEMS device structure is located the intermediate position of two groups of lead-out pads;Lead-out pad is provided with lead-out column;Packaging cover plate is connected with MEMS device wafer by encapsulation glue ring, encapsulation glue ring is located between MEMS device structure and lead-out pad, the thickness range of packaging cover plate is 5um-20um, the left and right sides of packaging cover plate are respectively provided with pad lead-out hole, the size of pad lead-out hole should be greater than the size of lead-out pad, pad lead-out hole is sleeved in lead-out column circumferential side.The device reduces the influence of packaging to MEMS movable device structure;While reducing cost, make cavity structure more fine so as to meet the wafer level packaging of MEMS device of different structural shape.

Description

Technical Field

[0001] This utility model relates to the field of MEMS packaging technology, and in particular to a MEMS packaging structure. Background Technology

[0002] MEMS (Micro-Electro-Mechanical Systems) refers to systems that integrate mechanical structures and electronic circuits at a microscale. They are characterized by miniaturization, low power consumption, and high sensitivity, and are widely used in smartphones, automobiles, medical devices, and many other fields. Because MEMS devices generally have movable mechanical structures, their packaging, in addition to meeting traditional packaging requirements, also needs to meet the following two conditions: 1. Sealed space: providing sufficient space for the mechanical structure to move and protecting it; 2. Providing interfaces with external systems and media: the casing must provide electrical connections such as power and signals. MEMS wafer-level packaging can achieve the fabrication space through cavity processing methods. Wire interconnection typically uses two methods: through-hole (TSV) and buried wire. TSV technology can achieve high-density lead outlays, but its processing cost is relatively high, offering no advantage for MEMS devices with low lead density. Furthermore, the complex structure can introduce significant stress into the MEMS device itself. Lateral lead interconnects have a simple structure and low cost, making them suitable for MEMS devices with a small number of leads. However, in current lateral lead packaging processes, the pad exposure process requires high precision in cutting, and even slight errors can damage the pads, making mass production difficult. Utility Model Content

[0003] To address the technical problems mentioned in the background section, this invention provides a MEMS packaging structure.

[0004] To achieve the above objectives, this utility model provides a MEMS packaging structure, comprising: a MEMS device wafer and a packaging cover plate. The device wafer is provided with a MEMS device structure and two sets of lead-out pads, which are correspondingly arranged. The MEMS device structure is located in the middle of the two sets of lead-out pads. Lead-out posts are provided on the lead-out pads. The packaging cover plate is connected to the MEMS device wafer through a packaging ring, which is located between the MEMS device structure and the lead-out pads. The thickness of the packaging cover plate is in the range of 5um-20um. Lead-out holes for the pads are respectively opened on the left and right sides of the packaging cover plate. The size of the lead-out holes for the pads should be larger than the size of the lead-out pads. The lead-out holes for the pads are sleeved around the lead-out posts.

[0005] Furthermore, the lead-out pad has a length of 0.8 mm, a width of 0.2 mm, and a thickness of less than 2 μm.

[0006] Furthermore, the lead-out post includes a post body and a tin cap. The diameter of the lead-out post body is 20 μm, and the height of the lead-out post body is 15 μm. The diameter of the tin cap is 20 μm, and the height of the tin cap is 5 μm.

[0007] Furthermore, the lead-out post is connected to the lead-out pad.

[0008] Furthermore, the material of the lead-out column is copper, and the material of the tin cap is tin; the column and the tin cap are solidly made and connected by electroplating.

[0009] Furthermore, the length of the pad lead-out hole is 1.2 mm, and the width of the pad lead-out hole is 0.4 mm.

[0010] Furthermore, the thickness of the encapsulation cover is 10µm.

[0011] Furthermore, the encapsulation ring is made of permanent bonding adhesive.

[0012] Furthermore, the length and width of the MEMS device wafer are both 2 mm.

[0013] Compared with existing technologies, this invention offers the following advantages: The MEMS packaging structure of this invention features a cover plate with a thickness of ≤20µm, and as thin as 5µm. This allows for the subsequent processing of lead-out posts after the initial packaging with the thin cover plate has fully protected the MEMS device structure, significantly reducing the impact of packaging on the MEMS movable device structure. The cavity structure formed by the packaging ring for the MEMS device structure avoids plasma etching or laser ablation of the cavity on the cover plate, greatly reducing costs while allowing for a more refined cavity structure, thus meeting the wafer-level packaging requirements for MEMS devices with different structural shapes. Furthermore, the lead-out holes on the cover plate enable the lead-out of the device pads, requiring only a single conventional cutting process to complete signal lead-out, greatly improving the reliability of related processes. Attached Figure Description

[0014] To more clearly illustrate the technical solutions in the embodiments of this utility model, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0015] Figure 1 This is a schematic diagram of the structure of this utility model;

[0016] Figure 2 This is a top view of the structure of this utility model;

[0017] Figure 3 This is a schematic diagram of the structure of the wafer of the novel MEMS device.

[0018] Figure 4 This is a schematic diagram of the structure of the encapsulation cover plate before thinning.

[0019] Figure 5 This is a schematic diagram of the structure when the encapsulation cover plate and the temporary bonding carrier plate of this utility model are temporarily bonded.

[0020] Figure 6 This is a schematic diagram of the structure of the packaging cover plate after thinning.

[0021] Figure 7 This is a schematic diagram of the structure after the encapsulation ring of this utility model has been manufactured;

[0022] Figure 8 This is a schematic diagram of the structure of the encapsulation ring after bonding to the MEMS device wafer according to this utility model.

[0023] Figure 9 This is a schematic diagram of the structure of this utility model after removing the temporary bonding carrier plate;

[0024] Figure 10 This is a schematic diagram of the structure of the present invention after the lead-out post is processed and divided into a single chip.

[0025] Figure labeling: 1-MEMS device wafer; 2-package cover plate; 3-MEMS device structure; 4-lead pad; 5-lead post; 6-package adhesive ring; 7-pad lead hole; 8-temporary bonding carrier. Detailed Implementation

[0026] The specific embodiments of this utility model will be further described below with reference to the accompanying drawings. It should be noted that these descriptions are for the purpose of aiding understanding of this utility model, but do not constitute a limitation thereof. Furthermore, the technical features involved in the various embodiments of this utility model described below can be combined with each other as long as they do not conflict with each other.

[0027] See the attached instruction manual. Figure 1-10This utility model provides a MEMS packaging structure, including: a MEMS device wafer 1 and a packaging cover plate 2. The length and width of the MEMS device wafer 1 are both 2mm. A MEMS device structure 3 and two sets of lead-out pads 4 are disposed on the MEMS device wafer 1, with the two sets of lead-out pads 4 correspondingly arranged. The MEMS device structure 3 is located in the middle of the two sets of lead-out pads 4. Lead-out posts 5 are disposed on the lead-out pads 4, with a diameter of 20µm and a height of 20µm. The lead-out posts 5 are connected to the lead-out pads 4. The packaging cover plate 2 is connected to the MEMS device wafer 1 via a packaging adhesive ring 6. The material of 6 is permanent bonding adhesive. The encapsulation ring 6 is located between the MEMS device structure 3 and the lead-out pad 4. The thickness of the encapsulation cover plate 2 ranges from 5um to 20um, and the thickness of the encapsulation cover plate 2 is usually 10um. Lead-out holes 7 are respectively opened on the left and right sides of the encapsulation cover plate 2. The size of the lead-out hole 7 should be larger than the size of the lead-out pad 4. Specifically, the length of the lead-out pad 4 is 0.8mm, the width of the lead-out pad 4 is 0.2mm, and the thickness of the lead-out pad 4 is less than 2um. The length of the lead-out hole 7 is 1.2mm, and the width of the lead-out hole 7 is 0.4mm. The lead-out hole 7 is sleeved around the lead-out post 5.

[0028] This application includes a MEMS device chip 1 with dimensions of 2 x 2 mm; a MEMS device structure 3 with dimensions of 0.5 x 0.5 mm; an overall size of 0.2 mm x 0.8 mm for the lead-out pads 4; a 200 μm width and a 0.7 x 0.7 mm sealing dimension for the encapsulation ring 6; a 10 μm thickness for the encapsulation cover plate 2; a 0.4 x 1.2 mm size for the lead-out holes 7; and a 20 μm diameter and 20 μm height for the lead-out posts 5. The encapsulation ring 6 is bonded to the MEMS device wafer 1. The lead-out posts 5 are electroplated onto the lead-out pads 4 and pass through the lead-out holes 7 to connect to external devices. The MEMS device wafer 1 and the MEMS device structure 3 are the pre-processing parts of the MEMS device. The purpose of this invention is to encapsulate and protect them while enabling signal extraction.

[0029] This utility model can be manufactured using the following method:

[0030] Step 1: Form a MEMS device wafer 1 containing MEMS devices using MEMS fabrication technology;

[0031] Step 2: Drill holes in the package cover 2 using conventional laser drilling technology. Based on the overall pad size of 0.2mm x 0.8mm, drill pad lead-out holes 7 at the corresponding positions in the package cover 2. The size of the pad lead-out holes 7 is 0.4 x 1.2mm. The size of the pad lead-out holes 7 is larger than the size of the corresponding lead-out pad 4, so that the pads can be exposed outside the package cover after packaging.

[0032] Step 3: The encapsulation cover plate 2 is temporarily bonded to the temporary bonding carrier plate 8. The temporary bonding carrier plate 8 uses 500um thick glass, and the temporary bonding uses temporary bonding adhesive, model TB4180.

[0033] Step 4: Thinning of the package cover 2: Thinning and polishing is performed using a wafer thinning machine and a wafer polishing machine to reduce the thickness to 10um, thus obtaining a thin package cover 2.

[0034] Step 5: Fabricate the encapsulation ring 6. Benzocyclobutene (BCB) permanent bonding adhesive is used. It is applied to the thin encapsulation cover plate 2, followed by photolithography, development, patterning, and pre-curing to form the encapsulation ring 6 corresponding to the MEMS device. The adhesive application parameters are 1500 r / min, and the pre-curing conditions are 110℃ / 10min. The BCB thickness after pre-curing is 3µm.

[0035] Step 6: Permanent bonding. Using a wafer alignment machine, the MEMS device structure 3 on the MEMS device wafer 1 is aligned one-to-one with the packaging cavity on the thin packaging cover plate 2. Then, using a wafer bonding machine, the MEMS device wafer 1 and the thin packaging cover plate 2 wafer are permanently bonded together by applying pressure and heating. The heating conditions are 280℃ / 1H, and the pressure conditions are 2000MBar.

[0036] Step 7: Electroplating process is used to electroplat the lead-out post 5; dicing is used to form a single chip, and a wafer dicing machine is used to dic the bonding wafer into a single chip.

[0037] From the above description, it can be seen that the above embodiments of this utility model achieve the following technical effects: the thickness of the packaging cover plate 2 is ≤20um, and the thinnest is 5um, which satisfies the condition that after the initial packaging of the thin packaging cover plate 2 has been completed, the MEMS device structure 3 has been completely protected, and then the lead-out post 5 is processed, which greatly reduces the impact of packaging on the MEMS movable device structure; the cavity structure formed by the packaging ring 6 for the MEMS device structure 3 avoids plasma etching or laser ablation of the cavity on the packaging cover plate 2, which can make the cavity structure more refined while greatly reducing the cost, thereby meeting the wafer-level packaging of MEMS devices with different structural shapes; the lead-out hole 7 of the pad on the packaging cover plate 2 realizes the lead-out of the device pad, and the signal lead-out can be completed by a single conventional cutting process, which greatly improves the reliability of related processes.

[0038] The embodiments of this utility model have been described in detail above with reference to the accompanying drawings, but this utility model is not limited to the described embodiments. For those skilled in the art, various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of this utility model, and these variations still fall within the protection scope of this utility model.

Claims

1. A MEMS packaging structure, characterized in that, include: MEMS device wafer (1) and packaging cover plate (2). The MEMS device wafer (1) is provided with MEMS device structure (3) and two sets of lead-out pads (4). The two sets of lead-out pads (4) are arranged correspondingly. The MEMS device structure (3) is located in the middle of the two sets of lead-out pads (4). Lead-out posts (5) are provided on the lead-out pads (4). The packaging cover plate (2) is connected to the MEMS device wafer (1) through a packaging ring (6). The packaging ring (6) is located between the MEMS device structure (3) and the lead-out pads (4). The thickness of the packaging cover plate (2) is in the range of 5um-20um. Lead-out holes (7) are opened on the left and right sides of the packaging cover plate (2). The size of the lead-out holes (7) should be larger than the size of the lead-out pads (4). The lead-out holes (7) are sleeved around the lead-out posts (5).

2. The MEMS packaging structure according to claim 1, characterized in that: The lead-out pad (4) has a length of 0.8 mm, a width of 0.2 mm, and a thickness of less than 2 μm.

3. The MEMS packaging structure according to claim 1, characterized in that: The lead-out post (5) includes a post body and a tin cap. The diameter of the post body is 20 μm and the height of the post body is 15 μm. The diameter of the tin cap is 20 μm and the height of the tin cap is 5 μm.

4. A MEMS packaging structure according to claim 3, characterized in that: The lead-out post (5) is connected to the lead-out pad (4).

5. A MEMS packaging structure according to claim 3, characterized in that: The material of the lead-out column (5) is copper, and the material of the tin cap is tin; the column and the tin cap are solidly made and connected by electroplating.

6. A MEMS packaging structure according to claim 1, characterized in that: The length of the pad lead-out hole (7) is 1.2 mm, and the width of the pad lead-out hole (7) is 0.4 mm.

7. A MEMS packaging structure according to claim 1, characterized in that: The thickness of the encapsulation cover (2) is 10 μm.

8. A MEMS packaging structure according to claim 1, characterized in that: The encapsulation ring (6) is made of permanent bonding adhesive.

9. A MEMS packaging structure according to claim 1, characterized in that: The MEMS device wafer (1) has a length and width of 2 mm.

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