MEMS sensor of EMIB and preparation method thereof

Abstract

The invention discloses an MEMS sensor of an EMIB and a preparation method of the MEMS sensor of the EMIB, and the preparation method of the MEMS sensor of the EMIB comprises the following steps: S1, providing a substrate with a groove; s2, mounting an ASIC chip in the groove of the substrate through a chip adhesive, and baking and curing the ASIC chip to form an interconnection bridge structure; s3, the two Si-based FC flip chips with the TSV structures are fixed to the substrate through the flip-chip bonding technology, and interconnection and conduction between the Si-based FC flip chips and the substrate are achieved through the backflow curing technology; s4, respectively mounting an MEMS accelerometer chip and an MEMS gyroscope chip on the surface of the Si-based FC flip chip through chip bonding glue, and baking and curing; s5, an MEMS accelerometer chip and an MEMS gyroscope chip are interconnected and conducted with the corresponding Si-based FC flip chips through a routing process; and S6, carrying out plastic packaging on the overall structure. According to the invention, the packaging boundary dimension of the sensor chip is further reduced, meanwhile, the interconnection efficiency and the signal transmission quality between the chips are improved, and the reject ratio of the manufacturing process is reduced.

Description

Technical Field

[0001] The present invention belongs to the field of semiconductor packaging, and in particular relates to an EMIB MEMS sensor and a preparation method thereof. Background Art

[0002] With the continuous advancement of semiconductor technology, sensor chip packaging technology has undergone numerous upgrades. During this process, EMIB (Embedded Multi-Die Interconnect Bridge) advanced packaging technology has gradually gained widespread application in the semiconductor packaging field. Through its innovative packaging structure, EMIB technology provides a smaller, more flexible, and more economical solution for semiconductor sensor packaging devices, meeting the market's urgent demand for miniaturization and higher performance. At the same time, MEMS (Micro-Electro-Mechanical Systems) products are also continuing to miniaturize, with package dimensions shrinking. This trend places higher demands on sensor chip packaging technology, requiring not only more compact packaging structures but also efficient interconnection and signal transmission quality between chips. Traditional packaging methods are gradually showing limitations in response to these requirements, such as large package sizes, high signal transmission losses, and high process defect rates. Summary of the Invention

[0003] In response to the problems existing in the prior art, the present invention provides an EMIB MEMS sensor and a preparation method thereof, which further reduces the external dimensions of the sensor chip package, while improving the interconnection efficiency and signal transmission quality between chips and reducing the process defect rate.

[0004] In order to solve the above technical problems, the present invention is implemented through the following technical solutions:

[0005] According to a first aspect of the present invention, a method for preparing an EMIB MEMS sensor is provided, comprising:

[0006] S1. providing a substrate with a groove;

[0007] S2, mounting the ASIC chip in the groove of the substrate by using adhesive, and baking and curing to form an interconnection bridge structure;

[0008] S3, fixing two Si-based FC flip chips with TSV structures on the substrate through a flip-chip bonding process, and achieving interconnection and conduction between the Si-based FC flip chips and the substrate through a reflow curing process;

[0009] S4, attaching the MEMS accelerometer chip and the MEMS gyroscope chip to the surface of the Si-based FC flip chip by adhesive, and baking and curing;

[0010] S5. Interconnecting the MEMS accelerometer chip and the MEMS gyroscope chip with the corresponding Si-based FC flip chip through a wire bonding process;

[0011] S6. Plastic-encapsulate the entire structure.

[0012] In a possible implementation manner of the first aspect, in step S1, the groove is located in a central area of ​​the substrate, and a depth of the groove is 80% to 95% of a thickness of the ASIC chip.

[0013] In a possible implementation of the first aspect, in step S2, the die bonding adhesive is DAF or thermosetting adhesive.

[0014] In a possible implementation of the first aspect, in step S3, the flip-chip bonding adopts a solder paste or micro-bump process.

[0015] In a possible implementation of the first aspect, in step S4, the die bonding adhesive is epoxy resin adhesive or polyimide adhesive, and the curing temperature range is 150° C. to 200° C.

[0016] In a possible implementation of the first aspect, in step S5, the wire bonding process uses gold wire or copper wire, and the bonding method is ball bonding or wedge bonding.

[0017] In a possible implementation of the first aspect, in step S6, the plastic encapsulation uses epoxy molding compound.

[0018] In a possible implementation of the first aspect, in step S6, the thickness of the plastic package covers all chips and extends beyond the substrate surface by 0.5 mm to 0.9 mm.

[0019] In a possible implementation of the first aspect, after the overall structure is plastic-sealed, the method further includes:

[0020] S7. Perform printing and cutting processes to form a single finished sensor structure.

[0021] According to a second aspect of the present invention, there is provided an EMIB MEMS sensor, comprising:

[0022] a substrate with grooves;

[0023] The ASIC chip fixed in the groove forms an interconnection bridge structure;

[0024] Two Si-based FC flip chips with TSV structures are fixed to the upper surface of the substrate by flip-chip welding and are interconnected and conductive with the substrate;

[0025] The MEMS accelerometer chip and the MEMS gyroscope chip are respectively attached to the surfaces of the two Si-based FC flip chips by adhesive.

[0026] Bonding wires, connecting the MEMS accelerometer chip, the MEMS gyroscope chip and the corresponding Si-based FC flip chip;

[0027] The plastic package covers the substrate, the ASIC chip, the Si-based FC flip chip, the MEMS accelerometer chip, the MEMS gyroscope chip and the bonding wires.

[0028] Compared with the prior art, the present invention has at least the following beneficial effects:

[0029] The present invention provides an EMIB MEMS sensor, which makes full use of the space of the substrate and effectively reduces the overall horizontal area occupied by the sensor by setting a groove on the substrate and embedding the ASIC chip in the groove. At the same time, a Si-based FC flip chip with a TSV structure is introduced. Compared with the traditional packaging method, this flip chip packaging method does not require additional lead frames and other structures, further compressing the packaging volume. Through these designs, the EMIB MEMS sensor of the present invention is further reduced in package size, meeting the market demand for product miniaturization, and can better adapt to various application scenarios with strict space requirements, such as wearable devices, portable electronic products, etc. In terms of interconnection between chips, first, the ASIC chip of the present invention is embedded in the groove of the substrate to form an interconnection bridge structure. This structure makes the electrical connection between chips more direct and efficient, reduces the intermediate links of signal transmission, and reduces the delay of signal transmission. Secondly, a Si-based FC flip chip with a TSV structure is introduced, and interconnection and conduction with the substrate are achieved through a flip-chip welding process. TSV technology (through silicon via technology) can realize vertical electrical connection inside the chip, greatly shortening the conduction path between chips. Compared with the traditional wire bonding method, the signal transmission path is shorter, thereby effectively reducing the loss during signal transmission and improving the speed of signal transmission. In addition, in terms of the interconnection between the MEMS accelerometer chip and the MEMS gyroscope chip and the Si-based FC flip chip, a wire bonding process is adopted for connection. The wire bonding process is optimized and designed to ensure the reliability of the electrical connection between the chips, further ensuring the quality of signal transmission. These measures work together to improve the efficiency of chip interconnection and signal transmission quality of the sensor of the present invention, meet the requirements of high-performance sensors for fast and accurate signal transmission, and improve the overall performance of the sensor. In the mounting process of ASIC chips, Si-based FC flip chips, MEMS accelerometer chips and MEMS gyroscope chips, adhesive is used for mounting, and a baking and curing process is used to ensure a firm connection between the chip and the substrate or other chips, so that the chip can be accurately positioned during the mounting process, reducing the adverse problems caused by mounting deviations. At the same time, the application of flip-chip soldering and reflow curing processes makes the connection between the Si-based FC flip chip and the substrate more reliable, avoiding the problems of poor bonding that can occur in traditional bonding processes. The combined application of these process measures effectively reduces the process defect rate, improves product quality, reduces the scrap rate during production, and reduces production costs.

[0030] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, preferred embodiments are given below and described in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the technical solutions in the specific embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the specific embodiments. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0032] Figures 1 to 6 Schematic diagram of the preparation process of an EMIB MEMS sensor.

[0033] In the figure: 100 - substrate; 101 - groove; 200 - ASIC chip; 300 - Si-based FC flip chip; 400 - MEMS accelerometer chip; 500 - MEMS gyroscope chip; 600 - bonding wire; 700 - plastic package. DETAILED DESCRIPTION

[0034] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of them. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0035] Example 1: Fabrication of MEMS (Micro-Electro-Mechanical Systems) Sensors for EMIB (Embedded Multi-Die Interconnect Bridge)

[0036] Step S1: providing a substrate 100 with a groove 101.

[0037] like Figure 1 As shown, a suitable material for the substrate 100 is selected, such as a common organic substrate with good electrical and mechanical properties. A groove 101 is formed in the central area of ​​the substrate 100 by machining or laser processing. Depending on the thickness of the ASIC (Application-Specific Integrated Circuit) chip 200, the depth of the groove 101 is set to 80%-95% of the thickness of the ASIC chip 200. For example, if the thickness of the ASIC chip 200 is 0.2 mm, the depth of the groove 101 can be set to 0.16 mm to 0.19 mm. Such a depth setting can ensure that the ASIC chip 200 is firmly embedded in the groove 101.

[0038] Step S2: attaching the ASIC chip 200 to the groove 101 of the substrate 100 by using adhesive, and baking and curing the adhesive to form an interconnection bridge structure.

[0039] like Figure 2 As shown, prepare an ASIC chip 200. The ASIC chip 200 serves as an interconnection bridge structure and plays a role in signal processing and interconnection in the sensor. Select a suitable adhesive. For example, the adhesive is DAF (Die Attach Film) or thermosetting glue. Apply the adhesive evenly on the back of the ASIC chip 200, then place the ASIC chip 200 in the groove 101 of the substrate 100, and apply appropriate pressure to make it fit tightly with the substrate 100. Afterwards, place the substrate 100 with the ASIC chip 200 in an oven for baking and curing. The curing temperature and time depend on the characteristics of the selected adhesive. For example, if thermosetting glue is used, the curing temperature can be set to 150°C and the curing time is about 1 to 2 hours to ensure that the adhesive is fully cured so that the ASIC chip 200 is firmly fixed in the groove 101 of the substrate 100 to form a stable interconnection bridge structure.

[0040] Step S3: fix the two Si-based FC flip chips 300 with TSV structures on the substrate 100 through a flip-chip bonding process, and achieve interconnection and conduction between the Si-based FC flip chips 300 and the substrate 100 through a reflow curing process.

[0041] like Figure 3 As shown, two Si-based FC flip chips 300 with TSV (Through Silicon Via) structures are prepared. TSV technology enables vertical interconnection between different layers within a chip, reducing the conductive path between chips and lowering signal transmission loss. The Si-based FC flip chips 300 are secured to the top surface of the substrate 100 using a flip-chip soldering process. Flip-chip soldering can be performed using either solder paste or micro-bumping. If solder paste is used, solder paste is first printed on the corresponding locations on the substrate 100. The solder balls of the Si-based FC flip chips 300 are then aligned with the solder paste locations on the substrate 100 for placement. The substrate 100 with the Si-based FC flip chips 300 mounted thereon is then placed in a reflow oven for reflow curing. The reflow oven's temperature profile is set based on the composition and properties of the solder paste and generally includes preheating, heating, reflow, and cooling stages. For example, the preheating stage temperature can be set to 100°C to 150°C. The temperature in the heating stage is gradually increased to the reflow temperature (approximately 220°C to 250°C), and the reflow time is controlled to be 30-60 seconds. Finally, cooling is performed to solidify the solder paste and achieve interconnection and conductivity between the Si-based FC flip chip 300 and the substrate 100. The Si-based FC flip chip 300 acts as an adapter plate in the sensor, facilitating the placement of the MEMS chip.

[0042] Step S4: attaching the MEMS accelerometer chip and the MEMS gyroscope chip to the surface of the Si-based FC flip chip by using adhesive, and baking and curing.

[0043] like Figure 4 As shown, prepare the MEMS accelerometer chip 400 and the MEMS gyroscope chip 500. These two chips are the core components of the sensor's inertial measurement function. Select a suitable die-bonding adhesive, such as epoxy or polyimide adhesive, which has excellent bonding and temperature resistance. Apply the die-bonding adhesive evenly to the backsides of the MEMS accelerometer chip 400 and the MEMS gyroscope chip 500. Then, attach them to the surfaces of two Si-based FC flip-chips 300, applying appropriate pressure to ensure a tight fit. Next, place the substrate 100 with the MEMS chips attached in an oven for baking and curing. The curing temperature ranges from 150°C to 200°C, and the curing time depends on the properties of the die-bonding adhesive and the size of the chips, typically 1 to 2 hours, to ensure that the die-bonding adhesive is fully cured, firmly securing the MEMS accelerometer chip 400 and the MEMS gyroscope chip 500 to the surfaces of the Si-based FC flip-chips 300.

[0044] Step S5: interconnecting the MEMS accelerometer chip 400 and the MEMS gyroscope chip 500 with the corresponding Si-based FC flip chip 300 through a wire bonding process.

[0045] like Figure 5 As shown, a wire bonding process is used to interconnect the MEMS accelerometer chip 400 and the MEMS gyroscope chip 500 with the corresponding Si-based FC flip chip 300. The wire bonding process can use gold or copper wire. Gold wire has good electrical conductivity, while copper wire has the advantage of lower cost. Ball bonding or wedge bonding can be used as the bonding method. For example, when using ball bonding, solder balls are first formed on the pads of the MEMS chip. Then, one end of the gold or copper wire is bonded to the solder ball, and the other end is bonded to the corresponding pad on the Si-based FC flip chip 300, achieving an electrical connection between the chips.

[0046] S6. Plastic-encapsulate the entire structure.

[0047] like Figure 6As shown, epoxy molding compound is used to encapsulate the entire structure. Epoxy molding compound has good insulation properties, mechanical properties and temperature resistance, and can effectively protect the chip and internal circuit. The substrate 100 with the chip mounted is placed in a plastic encapsulation mold, and then the epoxy molding compound is injected into the mold so that it covers the substrate 100, the ASIC chip 200, the Si-based FC flip chip 300, the MEMS accelerometer chip 400, the MEMS gyroscope chip 500 and the bonding wire 600. Preferably, the thickness of the plastic encapsulation needs to be controlled so that it covers all chips and extends beyond the surface of the substrate 100 by 0.5mm to 0.9mm. Such a plastic encapsulation thickness can not only ensure sufficient protection for the chip and the internal circuit, but also avoid excessive plastic encapsulation material resulting in an excessively large package size. After the plastic encapsulation is completed, the plastic encapsulation part is removed from the mold and cooled and solidified to completely solidify the epoxy molding compound to form a plastic encapsulation body 700.

[0048] S7. Perform printing and cutting processes to form a single finished sensor structure.

[0049] Specifically, the encapsulated structure undergoes a printing process, with the product model, batch number, and other relevant information printed on the surface of the encapsulated body 700 for easy identification and management. Subsequently, a cutting process is used to separate the entire structure into individual finished sensor structures. Cutting can be done mechanically or by laser, depending on the characteristics of the encapsulation material and the required cutting accuracy. The cutting process must avoid damaging the chip and internal circuitry, ultimately resulting in a single, qualified EMIB MEMS sensor.

[0050] Example 2

[0051] Based on the first embodiment, some parameters are adjusted as follows:

[0052] In step S1, the depth of recess 101 is set to 95% of the thickness of ASIC chip 200. For example, if ASIC chip 200 is 0.2 mm thick, the depth of recess 101 is set to 0.19 mm. Preparation is performed according to the subsequent steps of Example 1, and the placement of ASIC chip 200 and the stability of the overall package structure are observed. The results show that when the depth of recess 101 is 95% of the thickness of ASIC chip 200, ASIC chip 200 can still be firmly embedded in recess 101, and the subsequent packaging process can proceed smoothly, with the package structure being stable and reliable.

[0053] In step S2, a thermosetting adhesive was used as the die bonding adhesive, the curing temperature was set to 180°C, and the curing time was 1.5 hours. In step S4, a polyimide adhesive was used as the die bonding adhesive, the curing temperature was set to 170°C, and the curing time was 1.8 hours. The subsequent steps of Example 1 were followed to observe the chip placement effect and curing quality. The results showed that the chips were firmly fixed in place using different types of die bonding adhesives with different curing parameters, and the curing quality was good, with no problems such as chip detachment or poor bonding.

[0054] In step S3, flip-chip bonding is performed using a microbump process. Microbumps offer higher precision and better electrical performance, further improving the efficiency of chip-to-chip interconnects. Preparation is performed according to the subsequent steps of Example 1, and the soldered chips are subjected to electrical performance testing. The results show that flip-chip bonding using the microbump process reduces interconnect resistance between chips, minimizes signal transmission loss, and further enhances sensor performance.

[0055] In step S5, copper wire was used for wire bonding, with wedge bonding being the preferred bonding method. Preparation was performed according to the subsequent steps of Example 1, and the wire bonding quality was inspected. The results showed that the copper wire and wedge bonding method achieved satisfactory bonding strength, with no issues such as wire breakage or cold solder joints. Furthermore, the copper wire cost was relatively low, reducing the manufacturing cost of the sensor.

[0056] In step S6, the plastic encapsulation thickness was set to cover all chips and extend 0.5 mm beyond the surface of substrate 100. Preparation was performed according to the subsequent steps of Example 1, and the plastic encapsulation effect and package size were observed. The results showed that when the plastic encapsulation thickness was 0.5 mm, the plastic encapsulation body 700 provided more adequate protection for the chips and internal circuits, while the package size remained within a reasonable range, meeting the requirements for product miniaturization.

[0057] It can be seen from the above embodiments that the EMIB MEMS sensor and the preparation method thereof of the present invention can produce sensor products with good performance and stable structure under different parameter settings, which can meet the market demand for miniaturization and high performance of products.

[0058] In the description of the present invention, it should be understood that the terms "upper", "lower", "bottom", "inside", "outside", etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0059] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referred to. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of the present invention, "plurality" means at least two, such as two, three, etc., unless otherwise specifically defined.

[0060] In the present invention, unless otherwise specified or limited, the terms "connected" and "connection" should be understood in a broad sense. For example, they can mean fixed connection, detachable connection, or integration; mechanical connection, electrical connection, or communication; direct connection or indirect connection through an intermediate medium; internal communication between two elements or interaction between two elements, unless otherwise specified. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0061] In the present invention, unless otherwise expressly specified or limited, when a first feature is "above" or "below" a second feature, it may mean that the first and second features are in direct contact, or that the first and second features are in indirect contact through an intermediary. Furthermore, when a first feature is "above," "above," or "above" a second feature, it may mean that the first feature is directly above or diagonally above the second feature, or simply means that the first feature is at a higher level than the second feature. When a first feature is "below," "below," or "below" a second feature, it may mean that the first feature is directly below or diagonally below the second feature, or simply means that the first feature is at a lower level than the second feature.

[0062] In the present invention, the terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine different embodiments or examples described in this specification and the features of different embodiments or examples without contradiction.

[0063] Finally, it should be noted that the above-described embodiments are only specific implementation methods of the present invention, which are used to illustrate the technical solutions of the present invention rather than to limit them. The protection scope of the present invention is not limited thereto. Although the present invention has been described in detail with reference to the above-mentioned embodiments, ordinary technicians in this field should understand that any technician familiar with this technical field can still modify the technical solutions recorded in the above-mentioned embodiments within the technical scope disclosed by the present invention, or make equivalent replacements for some of the technical features therein; and these modifications, changes or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be covered by the protection scope of the present invention.

Claims

1. A method for preparing an EMIB MEMS sensor, characterized in that: include: S1, providing a substrate (100) with a groove (101); S2, attaching the ASIC chip (200) to the groove (101) of the substrate (100) by means of adhesive, and baking and curing the chip to form an interconnection bridge structure; S3, fixing two Si-based FC flip chips (300) with TSV structures on the substrate (100) through a flip-chip welding process, and achieving interconnection and conduction between the Si-based FC flip chips (300) and the substrate (100) through a reflow curing process; S4, attaching the MEMS accelerometer chip and the MEMS gyroscope chip to the surface of the Si-based FC flip chip by adhesive, and baking and curing; S5, interconnecting and conducting the MEMS accelerometer chip (400) and the MEMS gyroscope chip (500) with the corresponding Si-based FC flip chip (300) through a wire bonding process; S6. Plastic-encapsulate the entire structure.

2. The method for preparing an EMIB MEMS sensor according to claim 1, wherein: In step S1, the groove (101) is located in the central area of ​​the substrate (100), and the depth of the groove (101) is 80% to 95% of the thickness of the ASIC chip (200).

3. The method for preparing an EMIB MEMS sensor according to claim 1, wherein: In step S2, the bonding adhesive is DAF or thermosetting adhesive.

4. The method for preparing an EMIB MEMS sensor according to claim 1, wherein: In step S3, the flip-chip bonding adopts solder paste or micro-bump process.

5. The method for preparing an EMIB MEMS sensor according to claim 1, wherein: In step S4, the die bonding adhesive is epoxy resin adhesive or polyimide adhesive, and the curing temperature range is 150°C to 200°C.

6. The method for preparing an EMIB MEMS sensor according to claim 1, characterized in that: In step S5, the wire bonding process uses gold wire or copper wire, and the bonding method is ball bonding or wedge bonding.

7. The method for preparing an EMIB MEMS sensor according to claim 1, wherein: In step S6, the plastic packaging uses epoxy molding compound.

8. The method for preparing an EMIB MEMS sensor according to claim 7, characterized in that: In step S6, the thickness of the plastic package covers all the chips and extends beyond the surface of the substrate (100) by 0.5 mm to 0.9 mm.

9. The method for preparing an EMIB MEMS sensor according to claim 1, wherein: After the overall structure is plastic-sealed, it also includes: S7. Perform printing and cutting processes to form a single finished sensor structure.

10. A MEMS sensor of EMIB, characterized in that: include: A substrate (100) having a groove (101); An ASIC chip (200) fixed in the groove (101) forms an interconnection bridge structure; Two Si-based FC flip chips (300) with TSV structures are fixed to the upper surface of the substrate (100) by flip-chip welding and are interconnected and conductive with the substrate (100); The MEMS accelerometer chip (400) and the MEMS gyroscope chip (500) are respectively attached to the surfaces of the two Si-based FC flip chips (300) by adhesive tape; Bonding wires (600) connecting the MEMS accelerometer chip (400), the MEMS gyroscope chip (500) and the corresponding Si-based FC flip chip (300); The plastic package (700) covers the substrate (100), the ASIC chip (200), the Si-based FC flip chip (300), the MEMS accelerometer chip (400), the MEMS gyroscope chip (500), and the bonding wires (600).

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