阅读说明：本技术 一种mems封装过程中mems晶元的键合方法 (bonding method of MEMS wafer in MEMS packaging process ) 是由 王莉 张�浩 黄菲 卢秉恒 于 2019-09-03 设计创作，主要内容包括：本发明涉及一种MEMS封装过程中MEMS晶元的键合方法,解决了现有MEMS器件封装键合技术效率低、高温高压条件导致器件失效以及胶膜制备方法致使器件中微结构堵塞等问题。该方法的主要步骤包括：1、准备需要键合的两块MEMS晶元；2、图案化掩模的制备；3、胶粘剂的制备；4、制备键合胶膜；5、两块MEMS晶元粘接；6、将粘接完成的两块MEMS晶元放置在进行加温固化,从而实现了MEMS晶元的键合。(the invention relates to a bonding method of an MEMS wafer in an MEMS packaging process, which solves the problems that the existing MEMS device packaging bonding technology has low efficiency, the device fails under high-temperature and high-pressure conditions, and a microstructure in the device is blocked by a glue film preparation method. The method mainly comprises the following steps: 1. preparing two MEMS wafers to be bonded; 2. preparing a patterned mask; 3. preparing an adhesive; 4. preparing a bonding adhesive film; 5. bonding the two MEMS wafers; 6. and placing the two bonded MEMS wafers for heating and curing, thereby realizing bonding of the MEMS wafers.)

1. A bonding method of MEMS wafer in MEMS packaging process comprises the following steps:

Step 1: preparing two MEMS wafers to be bonded, and arranging first marks on the two MEMS wafers;

Step 2: preparing a patterned mask;

preparing a film, and arranging a microstructure pattern and a second mark which are amplified in proportion on the film in a photoetching mode according to the microstructure pattern of one MEMS wafer and the position of the first mark, so that the patterned mask is manufactured;

And step 3: preparing an adhesive;

and 4, step 4: preparing a bonding adhesive film;

Step 4.1: placing the MEMS wafer in the step 2 on a workbench utilizing silk screen equipment, and then placing a patterned mask on the MEMS wafer in the step 2;

step 4.2: aligning the second mark in the patterned mask with the first mark in the MEMS wafer in step 2;

Step 4.3: coating adhesive on the upper surface of the patterned mask, and pressing the adhesive onto the MEMS wafer in the step 2 from the upper surface of the patterned mask by using a scraper in a screen device;

step 4.4: taking away the patterned mask, and forming a patterned bonding adhesive film on the MEMS wafer in the step 2;

and 5: bonding the two MEMS wafers;

Aligning the first marks on the two MEMS wafers, and bonding the two MEMS wafers together by adopting a pressing tool;

Step 6: and heating and curing the two bonded MEMS wafers so as to realize bonding of the MEMS wafers.

2. the method of bonding a MEMS die in a MEMS packaging process of claim 1, wherein: the adhesive is prepared by uniformly mixing polyimide and epoxy resin in a volume ratio of 2:1 under the conditions of high-speed rotation and vacuum adsorption.

3. The method of bonding a MEMS die in a MEMS packaging process of claim 2, wherein: the diffusion coefficient of the adhesive in the heating and curing process is 0.05-0.5.

4. the method of bonding a MEMS die in a MEMS packaging process of claim 1, wherein: the first mark is at least two first positioning holes, the second mark is at least two second positioning holes, and the first positioning holes and the second positioning holes are identical in opening position and size.

5. The method of bonding a MEMS die in a MEMS packaging process of claim 4, wherein: the pressing tool comprises an upper pressing plate and a lower bottom plate; the lower bottom plate is provided with a threaded hole and two first positioning pin holes; the upper pressure plate is provided with a through hole matched with the threaded hole and two second positioning pin holes matched with the two first positioning pin holes, and the positions of the two first positioning pin holes correspond to the positions of the two first positioning holes in the MEMS wafer.

6. the method of bonding a MEMS die in a MEMS packaging process of claim 5, wherein: the concrete implementation steps of the step 5 are as follows:

Step 5.1: positioning pins are respectively inserted into the two first positioning pin holes of the lower bottom plate;

step 5.2: respectively aligning two first positioning holes of the MEMS wafer with the adhesive film with two positioning pins to position the MEMS wafer on the lower bottom plate;

step 5.3: aligning two first positioning holes of the other EMS wafer with two positioning pins respectively to position the EMS wafer on the MEMS wafer with the adhesive film;

Step 5.4: positioning the two second positioning pin holes of the upper pressure plate to the two positioning pins and placing the two positioning pins on the other MEMS wafer;

step 5.5: and screws are screwed up after penetrating through the through holes of the upper pressure plate and are matched with the threaded holes of the lower base plate, so that the two MEMS wafers are bonded.

7. The method of bonding a MEMS die in a MEMS packaging process of claim 1, wherein: the ratio of the microstructure pattern on the patterned mask to the microstructure pattern on the MEMS wafer is 0.5-0.95.

8. The method of bonding a MEMS die in a MEMS packaging process of claim 1, wherein: the temperature for heating and curing is 100-120 ℃.

Technical Field

the invention belongs to the technical field of semiconductors, and particularly relates to a bonding method of an MEMS wafer in an MEMS packaging process.

background

Mems (micro Electro Mechanical systems), which is a micro Electro Mechanical system, is a micro device or system that integrates a micro mechanism, a micro sensor, a micro actuator, and a signal processing and control circuit, until an interface, a communication, and a power supply are equal to one. Products manufactured based on the MEMS technology, such as micro actuators, micro sensors and micro components, are increasingly commonly applied in the fields of aviation, aerospace, automobiles, biomedicine, environmental monitoring, military and the like, and have very strong market competitiveness.

the MEMS manufacturing and packaging technology basically follows the Integrated Circuit (IC) manufacturing technology, but on one hand, the signals interacted between the MEMS device and the outside are not limited to electrical signals, but also include various signals such as mechanical signals, light signals, fluids, gases, and the like; on the other hand, some MEMS devices comprise multiple materials, multiple processing means; this makes the complexity and various external factors in the MEMS packaging process evasive, as detailed in document [1 ].

The bonding technology is widely used in the MEMS packaging process, mainly solves the problems of connection and sealing of MEMS devices, and can be divided into a direct thermal bonding technology and intermediate medium layer bonding, the direct thermal bonding technology is a bonding method without an intermediate medium, the mechanism is that under the action of external pressure and high temperature, bonding surfaces are in close contact to form intermolecular acting force so as to generate bonding strength, and the bonding technology can be divided into laser welding bonding, microwave welding bonding, plasma-assisted bonding, radiation degradation bonding and the like according to different mechanisms. The intermediate dielectric layer bonding is to prepare adhesive films with uniform thickness at the substrate wafers to perform adhesive bonding between the substrate wafers, as described in documents [2,4 ].

The bonding of the middle dielectric layer is an efficient and convenient bonding mode, and has the advantages of wide application material range, low cost, no need of heating or low temperature. However, the uniform adhesive film preparation technique is a major obstacle to the technical development, and the porosity of the adhesive film makes it difficult to obtain a completely tight seal, and the adhesive film is likely to cause the clogging of micro-channels when used in microfluidics, printhead chip bonding, and the biocompatibility problem of the adhesive used in biomedical applications, etc., as described in detail in document [3 ].

The preparation method of the adhesive film is a key of the middle layer bonding technology, and comprises various methods such as a high-speed whirl coating spin coating method, a precise dispensing preparation method, a micro-gravure coating method and the like, but for MEMS devices, surface structure diversity is caused, the surface is not a complete plane but has a certain microstructure, the high-speed whirl coating spin coating is difficult to uniformly and patternwise coat a cementing agent, and on the other hand, the device is scrapped because the adhesive enters the microstructure in the high-speed whirl coating process, such as microfluidics and printing head chips; the micro-gravure coating method is mainly suitable for the cementing agent coating of flexible film materials, and is not suitable for rigid wafers, and MEMS devices are processed based on rigid materials basically; although the precise dispensing technique can realize selective dispensing to realize patterning of the adhesive, it is inefficient and difficult to realize an ultra-thin adhesive film, as described in document [5 ].

the cited documents are as follows:

[1]TowardsDisposableLab-on-a-chip:Poly(Meth-ylmethacrylate) MicrochipEle ctrophoresisDevicewithElectrochemicalDetection.

[2] bonding technology and method of polymer microfluidic chip

[3]Adhesive wafer bonding for MEMS applications

[4]Application of Adhesives in MEMS and MOEMS Assembly:A Review

[5]Method for reducing the adhesive properties of MEMS and anti- adhesion-coated device US20050118742A1。

disclosure of Invention

the invention aims to provide a bonding method of an MEMS wafer in an MEMS packaging process, which solves the problems that the existing MEMS device packaging bonding technology is low in efficiency, the device fails under high-temperature and high-pressure conditions, a microstructure in the device is blocked due to a glue film preparation method, and the like.

the specific technical scheme of the invention is as follows:

The invention provides a bonding method of an MEMS wafer in an MEMS packaging process, which comprises the following steps:

Step 1: preparing two MEMS wafers to be bonded, and arranging first marks on the two MEMS wafers;

step 2: preparing a patterned mask;

preparing a film, and arranging a microstructure pattern and a second mark which are amplified in proportion on the film in a photoetching mode according to the microstructure pattern of one MEMS wafer and the position of the first mark, so that the patterned mask is manufactured;

And step 3: preparing an adhesive;

and 4, step 4: preparing a bonding adhesive film;

step 4.1: placing the MEMS wafer in the step 2 on a workbench utilizing silk screen equipment, and then placing a patterned mask on the MEMS wafer in the step 2;

step 4.2: aligning the second mark in the patterned mask with the first mark in the MEMS wafer in step 2;

Step 4.3: coating adhesive on the upper surface of the patterned mask, and pressing the adhesive onto the MEMS wafer in the step 2 from the upper surface of the patterned mask by using a scraper in a screen device;

step 4.4: taking away the patterned mask, and forming a patterned bonding adhesive film on the MEMS wafer in the step 2;

And 5: bonding the two MEMS wafers;

Aligning the first marks on the two MEMS wafers, and bonding the two MEMS wafers together by adopting a pressing tool;

Step 6: and heating and curing the two bonded MEMS wafers so as to realize bonding of the MEMS wafers.

furthermore, the adhesive is prepared by uniformly mixing polyimide and epoxy resin in a volume ratio of 2:1 under the conditions of high-speed rotation and vacuum adsorption.

furthermore, the diffusion coefficient of the adhesive in the heating and curing process is 0.05-0.5.

furthermore, the first mark is at least two first positioning holes, the second mark is at least two second positioning holes, and the positions and the sizes of the first positioning holes and the second positioning holes are the same.

further, the pressing tool comprises an upper pressing plate and a lower bottom plate; the lower bottom plate is provided with a threaded hole and two first positioning pin holes; the upper pressure plate is provided with a through hole matched with the threaded hole and two second positioning pin holes matched with the two first positioning pin holes, and the positions of the two first positioning pin holes correspond to the positions of the two first positioning holes in the MEMS wafer.

further, the step 5 is specifically realized by the following steps:

Step 5.1: positioning pins are respectively inserted into the two first positioning pin holes of the lower bottom plate;

Step 5.2: respectively aligning two first positioning holes of the MEMS wafer with the adhesive film with two positioning pins to position the MEMS wafer on the lower bottom plate;

step 5.3: aligning two first positioning holes of the other EMS wafer with two positioning pins respectively to position the EMS wafer on the MEMS wafer with the adhesive film;

step 5.4: positioning the two second positioning pin holes of the upper pressure plate to the two positioning pins and placing the two positioning pins on the other MEMS wafer;

Step 5.5: and screws are screwed up after penetrating through the through holes of the upper pressure plate and are matched with the threaded holes of the lower base plate, so that the two MEMS wafers are bonded.

Further, the ratio of the microstructure pattern on the patterned mask to the microstructure pattern on the MEMS wafer is 0.5-0.95.

further, the temperature for heating and curing is 100-120 ℃.

The invention has the beneficial effects that:

1. the invention adopts the patterned mask with a certain proportion as the intermediate medium in the glue scraping process, thereby avoiding the problem that the device is invalid due to the blocking of the MEMS wafer microstructure caused by the diffusion of the adhesive in the MEMS wafer. The method is simple, convenient and fast and can be implemented efficiently.

2. The thickness of the adhesive film is less than 10um after curing, and the uniform mixing of the adhesive and the removal of air bubbles in the adhesive are ensured through the formula of the adhesive and the preparation process of high-speed rotation and high-vacuum adsorption.

3. According to the invention, the adhesive is scraped onto the MEMS wafer at one time by adopting the scraper of the silk screen equipment, so that the consistency of the thickness of the adhesive film and the high efficiency of the process are ensured, and the problems that the area selectivity can be realized by precise dispensing in the existing method, but the efficiency is lower and the uniformity is difficult to ensure by a single-point dispensing mode are solved.

drawings

FIG. 1 is a flow chart of the method of the present invention.

FIG. 2 is a block diagram of a patterned mask;

FIG. 3 is a block diagram of a MEMS wafer;

fig. 4 is a structural diagram of the press-fitting tool.

the reference numbers are as follows:

1-a first positioning hole, 2-a second positioning hole, 3-an upper pressure plate, 4-a lower bottom plate, 5-a threaded hole, 6-a first positioning pin hole, 7-a through hole and 8-a second positioning pin hole.

Detailed Description

to make the objects, advantages and features of the present invention more apparent, a method for bonding a MEMS die in a MEMS packaging process according to the present invention will be described in detail with reference to the accompanying drawings and specific embodiments. Advantages and features of the present invention will become apparent from the following description and from the claims. It should be noted that: the drawings are in simplified form and are not to precise scale, the intention being solely for the convenience and clarity of illustrating embodiments of the invention; secondly, the structures shown in the drawings are often part of the actual structure; again, the drawings may require different emphasis, sometimes on different proportions.