CN104192791A - Cutting method for MEMS (Micro-electromechanical Systems) wafer - Google Patents

Abstract

The invention discloses a cutting method for an MEMS (Micro-electromechanical Systems) wafer. The cutting method comprises the following steps: carrying out uniform glue protection on the surface of the wafer (1) by using optical resist (4) and heating and curing, sticking a film on the front face by using an ordinary blue film (5), carrying out penetrating type cutting from the back of the wafer during cutting, soaking with acetone and alcohol respectively after the cutting is completed, taking out chips by using a pair of stainless steel tweezers after the glue is dissolved, putting the chips with microstructures in a flower basket with through holes in a chip accommodating area upward, then hanging the flower basket in a beaker, inserting a nitrogen pipe to the bottom of the beaker, and drying the alcohol on the chips with an appropriate amount of nitrogen; Then taking the chips out from the flower basket and putting in a special MEMS chip storage box, and putting the chips in a nitrogen cabinet for standby use together with the storage box after the chips are completely treated. The method disclosed by the invention can effectively prevent chippings from falling in the microstructure during the cutting process, the production and processing technology is simple, the operation is easy, the rate of finished products is high, and the processing is not limited by dimensions and shapes of the microstructures.

Description

A kind of cutting method of MEMS wafer

Technical field:

The present invention relates to a kind of cutting method of MEMS wafer.

Background technology:

Compared with traditional IC wafer; MEMS device has sandwich construction, generally has two-layerly and three layers, and the general the superiors of three-decker are protective layer; protect the mechanical micro-structural in intermediate layer; cutting difficulty is lower, and the device of double-layer structure to be generally micro-structural be exposed to outside, a little less than these micro-structurals are highly brittle; follow-up processing need to not only will avoid touching micro-structural; will note avoiding particle to enter in micro-structural, cutting difficulty is large simultaneously, and the application is for the MEMS device cutting of double-layer structure.Semiconductor packages break is for purifying worker-house, it is unique that what can produce dust granules is that wafer is cut in the process of one single chip, at present, MEMS cutting mainly contains back side water cutter hemisect and laser cutting, and laser cutting machine is expensive, cause cutting cost higher, MEMS wafer is thicker simultaneously, need to adopt repeatedly laser cutting, causes like this upgrading layer place to produce a large amount of larger particles, easily drop into chip surface, easily cause MEMS component failure.Back side water cutter hemisect, then sliver can produce particle equally in the time of sliver, very easily fall in micro-structural, and while sliver technique can produce irregular front sliver and collapse limit, can cause that chip destroys, and affects the reliability of device when serious.

Meixin Semi-conductor (Wuxi) Co. Ltd., application MEMS method for cutting wafer patent, this patent be mainly by be provided with MEMS structure hole one by one corresponding film be attached to wafer frontside, again second complete film is attached to first above film, use Ear Mucosa Treated by He Ne Laser Irradiation wafer frontside to inner, form upgrading layer in wafer frontside, then form labeled slots at the back side illuminaton of front upgrading layer correspondence position, then make water cut from back side hemisect to front upgrading layer, the shortcoming of the method is: (1) before pad pasting, need first film to punch, film after punching and MEMS device require aligning accuracy high while carrying out pad pasting, and require disposable pad pasting success, cause like this pad pasting difficulty large, be easy to pad pasting failure, (2) on the MEMS wafer of general volume production, between chip, spacing only has a hundreds of micron, and between the Kong Yukong on first film, spacing only has a hundreds of micron, is difficult to like this film after punching to take out, and is attached to accurately on MEMS wafer.

Zhongxin International Integrate Circuit Manufacture (Shanghai) Co Ltd.; apply for a kind of MEMS structure cuts separation method; can find out by this patent Introduction; this patent is the MEMS device cutting for the equal matcoveredn structure of levels, and this patent is mainly the solution that solves contaminated electrode in cutting process.And the method for patent Introduction can not be directly used in micro-structural and cruelly leak at surperficial MEMS device, if directly use ultraviolet film to stick on the MEMS chip of surface with micro-structural, after having cut, use ultraviolet ray to irradiate, because postradiation ultraviolet film still has certain viscosity, directly getting chip still can deface micro-structural.

Yantai Raytron Technology Co., Ltd., a kind of MEMS silicon wafer scribing cutting and the structure method for releasing of application, its patent is mainly by pasting UV film at wafer rear, then carry out substep cutting from front, its beneficial effect is to reduce front and back chip to collapse angle problem, then carries out structure release.If but its shortcoming is (1) to adopt hemisect, releasing structure, then carry out the manual sliver in the back side, meeting deface micromechanics mechanism; If (2) adopt full cutting, releasing structure, carries out when structure discharges utilizing the techniques such as photoetching, and photoetching process need to be carried out registering, and after chip has been separated, the chip being placed in frock has locational error, causes like this photoetching operability poor.

Summary of the invention:

The object of the invention is to solve large, the ropy shortcoming of scribing difficulty that prior art exists, the cutting method of a kind of MEMS wafer providing.

The present invention is by the following technical solutions:

A cutting method for MEMS device, comprises the following steps:

(1). first make with photoresist disk surfaces to be cut to be carried out even glue protection;

Select photoresist, because photoresist is dissolvable in water acetone, acetone is the normal solvent using in encapsulation process, and photoresist can immerse in micro-structural when cutting and follow-up transhipment are processed the micro-structural of device is formed once and protected;

(2). adopt cutting normal blue film to carry out pad pasting protection to even glue face, this pad pasting is scribing pad pasting simultaneously;

(3). disk is arranged on scribing machine and cuts;

Because pad pasting face has structural plane, so scribing sucker is required to be the tiny ceramic sucker of sucker, blue film protection and the protection of even glue form duplicate protection, can effectively avoid the silicon bits that produce in cutting process to enter in micro-structural cavity;

(4). after having cut, the chip that first uses cleaning machine that cutting is produced cleans, the disk after cutting is put into acetone soln and soaked, until photoresist all dissolves;

(5). then use alcohol-pickled, 3 minutes;

(6). take out after chip (i.e. disk after cutting), micro-structural is held to the gaily decorated basket of chip region with through hole towards above putting into, the gaily decorated basket is suspended in beaker, nitrogen tube is inserted into beaker bottom, adopts the mode of gas backstreaming, the alcohol of chip surface is dried up.

Owing to having adopted technique scheme, can effectively avoid chip in cutting process to fall in micro-structural, production and processing technology is simple, easy to operate, and yield rate is high, and process is without microstructure size and shape restriction.

brief description of the drawings:

Fig. 1 is that the present invention cuts MEMS chip schematic diagram;

Fig. 2 is MEMS chip schematic diagram after even glue of the present invention;

Fig. 3 is the MEMS chip schematic diagram after even bond paper facing of the present invention;

Fig. 4 is that the present invention cuts rear disk photoresist and blue film is processed schematic diagram;

Fig. 5 is that after separating in the present invention, little chip dries up alcohol installation drawing.

detailed description of the invention:

1.MEMS wafer is introduced, referring to Fig. 1

MEMS wafer rear has substrate 3, there are silicon chip 1 and the micro-structural of making on silicon chip and the cavity 2 of making micro-structural in surface, and this micro-structural 2 cannot be born pressure, in cutting process, the particle producing can not fall in a micro-structural and cavity thereof, otherwise may cause the disabler of device.

2. even glue protection, referring to Fig. 2

First the disk surfaces with micro-structural is carried out to even resist coating 4; this photoresist can temporary protection micro-structural and cavity thereof; require photoresist to want above micro-structural, to form the uniform diaphragm of one deck; the even painting of every wafer 2ml colloid; after even glue, need wafer to toast (temperature: 120 DEG C, time: 5 minutes) in baking oven, photoresist is solidified.

3. pad pasting protection, referring to Fig. 3

Use laminator to paste normal blue film 5 from even resist coating face; when pad pasting, sucker need to be heated; without opening vacuum suction; after pad pasting, whole disk is placed on to (temperature: 80 DEG C, time: 20 minutes) in baking oven simultaneously and toasts increase viscosity; blue film and photoresist form duplicate protection to micro-structural, can effectively avoid the chip of parameter in cutting to enter in micro-structural and cavity thereof.

4. disk cutting

(1) cut knife up: be 1/3 of paster film thickness, if the blue film thickness of the paster using is 0.075mm, cutting knife up is set to: 0.05

(2) the speed of mainshaft: 20000R/min～30000R/min

(3) feed velocity: 2mm/s～3mm/s.

5. after cutting, clean

Use cleaning machine, the chip remaining in cutting groove producing in cutting process is cleaned up.Crystalline phase test under microscope at 100 times is as the criterion.

6. striping and photoresist, referring to Fig. 4,5

(1) the wafer after cutting being put into the ready culture dish 8 with clean acetone 7 soaks 1 hour, then after acetone being changed, soak again 0.5 hour, so repeatedly until chip microcavity is interior without photoresist, require acetone liquid level to exceed the thickness of whole wafer, change solution simultaneously and need to use injection needle to operate, avoid directly pouring into chip micro-structural is impacted;

(2) chip is held to the gaily decorated basket and put into another and be ready to have the culture dish of clean alcohol, wherein alcohol liquid level covers scribing chip and holds face, by chip 10 micro-structurals after separating face up be placed in the gaily decorated basket hold district 14 with through hole 11 chip region.Soak time 3 minutes.

7. dry processing, specifically sees Fig. 5

(1) chip takes out the whole gaily decorated basket after taking from the culture dish with spirit solvent, and gaily decorated basket handle 9 is hung at beaker mouth place 12, and the gaily decorated basket that is contained with chip is suspended in beaker;

(2) ready nitrogen tube 13 is inserted into beaker bottom, opens suitable nitrogen, allow reflux gas by gaily decorated basket through hole with above the gaily decorated basket, the solvent in chip bottom and micro-structural be dried up;

(3) the gaily decorated basket that holds chip is put into infrared baking box (40 DEG C～60 DEG C of temperature ranges) and toasted 3min, then use sharp tweezers that chip is taken out and is placed on filter paper from the gaily decorated basket, leave in nitrogen cabinet stand-by.

Claims (1)

1. a cutting method for MEMS wafer, is characterized in that comprising the following steps:

(1). make with photoresist disk surfaces to be cut to be carried out even glue protection;

(2). adopt cutting normal blue film to carry out pad pasting protection to even glue face;

Disk is arranged on scribing machine and is cut;

(4). after having cut, the chip that first uses cleaning machine that cutting is produced cleans, then the disk after cutting is put into acetone soln and soak, until photoresist all dissolves;

(5). then use alcohol-pickled, 3 minutes;

(6). take out after disk by micro-structural towards upper, put into and hold the gaily decorated basket of chip region with through hole, the gaily decorated basket is suspended in beaker, nitrogen tube is inserted into beaker bottom, adopt the mode of gas backstreaming, the alcohol of disk surfaces is dried up.