CN101780942B

CN101780942B - Wafer level vacuum packaging method of MEMS (Micro-electromechanical System) component

Info

Publication number: CN101780942B
Application number: CN2009102279899A
Authority: CN
Inventors: 徐永青; 杨拥军; 胥超; 罗蓉
Original assignee: CETC 13 Research Institute
Current assignee: CETC 13 Research Institute
Priority date: 2009-12-11
Filing date: 2009-12-11
Publication date: 2011-12-14
Anticipated expiration: 2029-12-11
Also published as: CN101780942A

Abstract

The invention discloses a wafer level vacuum packaging method of an MEMS (Micro-electromechanical System) component, which realizes the packaging of a packaging cover plate and the MEMS component by adopting an eutectic bonding technology. The method comprises the steps of: (1) carrying out double-side polishing on the packaging cover plate; (2) depositing insulating media on two sides of the packaging cover plate; (3) preparing a metal film which is used for metal-silicon bonding on the packaging cover plate; (4) preparing an electrode outlet through hole; and (5) carrying out bonding packaging on the packaging cover plate and the MEMS component. By preparing the metal film which is used for metal-silicon bonding on the packaging cover plate, the invention omits the process for preparing bonding metal layer during processing the MEMS component, reduces the pollution of metal to MEMS components in production process, improves the process compatibility and further improves the performance of the MEMS components.

Description

MEMS device disc grade vacuum packaging method

Technical field

The present invention relates to a kind of method for packing, especially a kind of wafer-grade vacuum encapsulation method that is used for MEMS (microelectromechanical systems) device.

Background technology

The MEMS encapsulation technology is an important research direction in the MEMS research field, encapsulation can make the MEMS product avoid being subjected to the influence to movable structure such as dust, moisture on the one hand, also can change the internally-damped situation of MEMS product by vacuum or level Hermetic Package on the other hand, improve the performance of product.

Wafer-Level Packaging Technology is to realize the main solution route of MEMS device high-performance, low cost and mass, wafer level packaging is to adopt bonding techniques to install cover plate additional on the disk of MEMS device to finish encapsulation, therefore has advantage in batches, and owing to can save expensive package casing, it is minimum that packaging cost is dropped to.Realize the bonding techniques of wafer level packaging, mainly comprise anode linkage (silicon-glass bonding), silicon fusion bonding, Glass frit bonding, gold silicon eutectic bonding, polymer-bound etc., wherein the gold silicon eutectic bonding techniques has advantages such as technology is simple, rate of finished products is high, air-tightness is good, is the first-selection of Vacuum Package bonding techniques.In addition; the material that can be used as encapsulation cover plate has multiple; materials such as pottery, quartz, glass, silicon for example; taking all factors into consideration these factors such as processing compatibility, technology difficulty, processing cost, air-tightness, to choose silicon materials be a present main flow trend as the cap flaggy; this mainly be because present most of MEMS devices all be manufactured on silica-based on; the technical maturity compatibility is good; and silicon has good mechanical performance and air-tightness, can realize good protection and Vacuum Package to the MEMS device architecture.

The encapsulation technology of present hysteresis and high packaging cost have seriously restricted the industrialized development of MEMS device, the packaging cost of MEMS device has at most accounted for 95% of product total cost, therefore, need to optimize process technology and vacuum sealing technique, reduce packaging cost, improve the MEMS device performance, this realization for the final industrialization of MEMS technology is significant.

Summary of the invention

The technical problem to be solved in the present invention provides a kind of MEMS device disc grade vacuum packaging method, is subjected to pollution problems to solve in MEMS device manufacturing process complexity and the manufacturing process.

For solving the problems of the technologies described above, the technical solution used in the present invention is: a kind of MEMS device disc grade vacuum packaging method, the step of this method comprises: 1) deposit gold silicon bonding metallic film on the MEMS device, 2) twin polishing encapsulation cover plate, 3) the two-sided deposit dielectric of encapsulation cover plate, 4) the etching electrode is drawn through hole, 5) adopt the gold silicon eutectic bonding techniques that encapsulation cover plate and MEMS device are carried out bonding and encapsulate 6) by deposit, photoetching, be etched in electrode and draw the MEMS device surface of through hole correspondence and prepare MEMS device extraction electrode; Key is: omit above-mentioned steps 1) and in above-mentioned steps 3) and step 4) between increase following step: deposition gold silicon bonding metallic film on encapsulation cover plate.

Adopt the beneficial effect that technique scheme produced to be: to use deposit metal films on encapsulation cover plate the gold silicon bonding, saved and made the technology of gold silicon bonding in the MEMS device fabrication process with metallic film, reduced the pollution that metal pair MEMS device produces in manufacturing process, improve processing compatibility, and then improved the performance of MEMS device.

As further improved technical scheme of the present invention: after the twin polishing encapsulation cover plate, be increased in and make the step that electricity is isolated step automatically on the encapsulation cover plate, its effect is: will carry out bulk metalization to encapsulation cover plate after follow-up wafer bonding technology, when the growing metal film owing to there is electricity automatically to isolate the effect of blocking of step, the metallic film of MEMS device extraction electrode and on every side metallic film are separated automatically, reach the effect that electricity is isolated automatically, this technology utilization self-aligned technology has saved the photoetching process of a metal film electrode.

Description of drawings

The present invention is further detailed explanation below in conjunction with the drawings and specific embodiments.

Fig. 1 is the MEMS device encapsulation structure schematic diagram that adopts the present invention to make;

Fig. 2-1～Fig. 2-12 is a concrete process flow diagram of the present invention;

The polishing of Fig. 2-1 material; The positive photoetching of Fig. 2-2 encapsulation cover plate; Fig. 2-3 encapsulation cover plate front body silicon etching; Fig. 2-4 deposit dielectric; Fig. 2-5 depositing metal films; Fig. 2-6 photoetching metallic film; Fig. 2-7 etching metallic film; The back side photoetching of Fig. 2-8 encapsulation cover plate; Fig. 2-9 etching dielectric; Fig. 2-10 cap plate body silicon etching; 2-11 encapsulation cover plate and MEMS device gold silicon eutectic bonding; Fig. 2-12 surface metalation;

Among the figure, 1-encapsulation cover plate, 1a-encapsulation cover plate front, the 1b-encapsulation cover plate back side, 2-gold silicon bonding metallic film, the 3-electricity is isolated step automatically, the 4-dielectric, the 5-electrode is drawn through hole, 6-MEMS device extraction electrode, 7-metallic film, 8-MEMS device, 100,200, the 300-photoresist.

Embodiment

Fig. 1 is a MEMS device cell encapsulating structure schematic diagram, is followed successively by encapsulation cover plate 1 and MEMS device 8 from top to bottom, and encapsulation cover plate 1 bonds together by the gold silicon eutectic bonding with MEMS device 8.

Carry out the embodiment explanation below in conjunction with Fig. 2-1～Fig. 2-12 couple the present invention.

A kind of MEMS device disc grade vacuum packaging method, the step of this method comprises: 1) deposit gold silicon bonding metallic film 2 on the MEMS device, 2) the twin polishing encapsulation cover plate 1,3) encapsulation cover plate 1 two-sided deposit dielectric 4,4) the etching electrode is drawn through hole 5,5) adopt the gold silicon eutectic bonding techniques that encapsulation cover plate 1 and MEMS device 8 are carried out bonding encapsulation, 6) by deposit, photoetching, be etched in electrode and draw the MEMS device surface of through hole 5 correspondences and prepare MEMS device extraction electrode; Key is: omit above-mentioned steps 1) and in above-mentioned steps 3) and step 4) between increase following step: deposition gold silicon bonding is with metallic film 2 on encapsulation cover plate 1.

In the said method, described on encapsulation cover plate 1 preparation gold silicon bonding with the concrete steps of metallic film 2 be:

1. at encapsulation cover plate front (1a) growth gold silicon bonding metallic film (2);

2. photoetching obtains gold silicon eutectic bonding regional graphics;

3. etch away nonbonding zone gold silicon bonding with metallic film (2), keep bonding zone gold silicon bonding metallic film (2).

In the said method, in described step 2) and step 3) between be increased on the encapsulation cover plate 1 and make the step that electricity is isolated step 3 automatically, concrete implementation step is:

1. the positive 1a of photoetching encapsulation cover plate obtains electricity isolation step 3 figures and package cavity volume graphic automatically;

2. the etching encapsulation cover plate 1, forms to isolate step 3 and encapsulation cavity automatically.

In the said method, described electricity is isolated step 3 automatically and is positioned at electrode and draws around through hole 5 bottoms.

In the said method, described electrode is drawn through hole 5 and is the V-type through hole, and concrete preparation process is:

1. photoetching encapsulation cover plate back side 1b forms the V-type via hole image;

2. body silicon etching encapsulation cover plate 1 forms the V-type through hole.

In the said method, described dielectric 4 is the combination of silica or silicon nitride or silica and silicon nitride.

In the said method, described employing gold silicon eutectic bonding techniques to the processing step that encapsulation cover plate 1 and MEMS device 8 carry out the bonding encapsulation is:

1. under the vacuum state, positive 1a of encapsulation cover plate and MEMS device 8 carry out eutectic bonding, form the wafer level Vacuum Package;

2. at encapsulation cover plate back side 1b depositing metal films 6, form MEMS device extraction electrode 7, finish packaging technology.

In the said method, described encapsulation cover plate 1 material is preferably silicon materials.

Further can be summarized as following complete operation:

1) material is prepared: the silicon chip of employing＜100〉crystal orientation is as encapsulation cover plate 1, and silicon wafer thickness is generally greater than 200 μ m, and the disk size is identical with the disk of the MEMS device 8 that processes that will encapsulate, and Fig. 2-1 is participated in twin polishing.

2) photoetching: positive 1a applies photoresist 100 at encapsulation cover plate, obtains electricity by exposure, development and isolates step 3 figures and package cavity volume graphic automatically.Referring to Fig. 2-2.

3) the etching encapsulation cover plate 1: adopt isotropic dry etch technology that the positive 1a of encapsulation cover plate is carried out etching, the etching depth scope generally between 5 μ m～50 μ m, forms electricity and isolates step 3 and encapsulation cavity automatically.Referring to Fig. 2-3.

4) deposit: one or more layers dielectric 4 of growing on the two sides of encapsulation cover plate 1, dielectric 4 is generally silica, silicon nitride and their combination, and dielectric thickness is generally greater than 1 μ m, referring to Fig. 2-4.

5) metallization: with metallic film 2, be preferably chromium or titanium or gold at the positive 1a growth of encapsulation cover plate one deck gold silicon bonding, the thickness of chromium or titanium is generally 10nm～30nm, and the thickness of gold is generally greater than 1um, referring to Fig. 2-5.

6) photoetching: with applying photoresist 200 on the metallic film 2, obtain the figure in gold silicon eutectic bonding zone by exposing, developing, referring to Fig. 2-6 at the gold silicon bonding.

7) etching gold silicon bonding is with metallic film 2: remove the gold silicon bonding usefulness metallic film 2 in nonbonding zone with corrosion of metals liquid under photoresist 200 protections, referring to Fig. 2-7.

8) dual surface lithography: on the 1b of the encapsulation cover plate back side, apply photoresist 300, obtain the figure that the V-type electrode is drawn through hole 5 upper sheds by exposure, development, referring to Fig. 2-8.

9) etching dielectric: under photoresist 300 protections, erode the dielectric 4 that the V-type electrode is drawn through hole 5 upper sheds, referring to Fig. 2-9 with the dielectric corrosive liquid.

10) adopt anisotropic wet or dry etch process, etching encapsulation cover plate silicon chip forms the V-type electrode and draws through hole 5, referring to Fig. 2-10.

11) gold silicon bonding: under vacuum state, (be generally less than 1 atmospheric pressure, scalable), the front and MEMS device 8 disks of encapsulation cover plate 1 silicon chip are carried out eutectic bonding, form the wafer level Vacuum Package, referring to Fig. 2-11.

12) metallization: growing metal film 7 on the dielectric of encapsulation cover plate back side 1b, be preferably chromium or titanium or gold, the thickness of chromium or titanium is generally 10nm～30nm, the thickness of gold is generally greater than 100nm, form the metal extraction electrode 6 of MEMS device 8, finish packaging technology, referring to Fig. 2-12.

Photoetching described in the above processing step, etching, deposit, metallization are technology that those skilled in the art know, this no longer huge legendary turtle state.

Claims

1. MEMS device disc grade vacuum packaging method, the step of this method comprises: 1) twin polishing encapsulation cover plate (1); 2) photoetching encapsulation cover plate front (1a) obtains electricity isolation step (3) figure and package cavity volume graphic automatically; 3) etching encapsulation cover plate (1) forms electricity and isolates step (3) and encapsulation cavity automatically; 4) the two-sided deposit dielectric of encapsulation cover plate (1) (4); 5) at encapsulation cover plate front (1a) growth gold silicon eutectic bonding metallic film (2); 6) photoetching metallic film (2) obtains gold silicon eutectic bonding regional graphics; 7) be etched away nonbonding zone gold silicon bonding metallic film (2); 8) the photoetching encapsulation cover plate back side (1b) forms the figure that the V-type electrode is drawn through hole (5) upper shed; 9) etch away the dielectric (4) that the V-type electrode is drawn through hole (5) upper shed; 10) etching encapsulation cover plate (1) forms the V-type electrode and draws through hole (5); 11) under vacuum state, encapsulation cover plate front (1a) carried out eutectic bonding with MEMS device disk (8), form the wafer level Vacuum Package; 12) go up growing metal film (7) at the dielectric (4) of the encapsulation cover plate back side (1b), form the metal extraction electrode (6) of MEMS device (8), finish packaging technology.

2. method according to claim 1 is characterized in that described electricity isolates step (3) automatically and be positioned at electrode and draw around through hole (5) bottom.

3. method according to claim 1 is characterized in that the combination of described dielectric (4) for silica or silicon nitride or silica and silicon nitride.

4. according to claim 1 or 2 or 3 described methods, it is characterized in that described encapsulation cover plate (1) material is silicon materials.