CN109205552A - A method of back corrosion cutting MEMS silicon wafer - Google Patents
A method of back corrosion cutting MEMS silicon wafer Download PDFInfo
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- CN109205552A CN109205552A CN201710549657.7A CN201710549657A CN109205552A CN 109205552 A CN109205552 A CN 109205552A CN 201710549657 A CN201710549657 A CN 201710549657A CN 109205552 A CN109205552 A CN 109205552A
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B81—MICROSTRUCTURAL TECHNOLOGY
- B81C—PROCESSES OR APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OR TREATMENT OF MICROSTRUCTURAL DEVICES OR SYSTEMS
- B81C1/00—Manufacture or treatment of devices or systems in or on a substrate
- B81C1/00436—Shaping materials, i.e. techniques for structuring the substrate or the layers on the substrate
- B81C1/00523—Etching material
- B81C1/00531—Dry etching
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B81—MICROSTRUCTURAL TECHNOLOGY
- B81C—PROCESSES OR APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OR TREATMENT OF MICROSTRUCTURAL DEVICES OR SYSTEMS
- B81C1/00—Manufacture or treatment of devices or systems in or on a substrate
- B81C1/00436—Shaping materials, i.e. techniques for structuring the substrate or the layers on the substrate
- B81C1/00523—Etching material
- B81C1/00539—Wet etching
Abstract
The invention discloses a kind of methods of back corrosion cutting MEMS silicon wafer, the method is main are as follows: combines mode with wet etching using dry etching at the MEMS silicon wafer back side, while preparing heat-insulation chamber, back corrosion is carried out to MEMS silicon wafer and forms corrosion structure.Specific steps are as follows: (1) carry out optical exposure at the MEMS silicon wafer back side, development obtains cutting line；(2) dry etching is carried out at the MEMS silicon wafer back side using photoresist as exposure mask, then removes photoresist；(3) composite layer not removed using in step (2) by dry etching is carried out wet etching to the MEMS silicon wafer back side, obtains heat-insulation chamber and corrosion structure as exposure mask.Method of the invention is it is possible to prevente effectively from the problems such as surface damage, the clast that generate in machine cuts and laser cutting process pollute, high yield rate has good economy and convenience.
Description
Technical field
The invention belongs to the micro-nano processing of MEMS and Wafer Dicing technical fields, are related to a kind of MEMS Silicon Wafer
The cutting method of piece more particularly to a kind of method of back corrosion cutting MEMS silicon wafer.
Background technique
MEMS (MEMS, Micro-Electro-Mechanical System) is with microelectronics and micro Process skill
Based on art, integrate the microdevice or system of microsensor, microactrator and micro mechanical structure etc., there is high integration
The advantages that with low cost.MEMS device usually has multilayered structure, needs to combine a variety of micro fabrications such as photoetching, plated film and corrosion
It realizes.MEMS wafer needs to carry out cutting scribing after completing these production process, i.e., entire silicon wafer is cut into individually
MEMS chip, then could by welding and encapsulation process at product.
Currently, wafer cutting technique mainly has machine cuts and laser cutting.
Machine cuts have the following problems using the mode of action of mechanical force: (1) being easy to generate in crystals and answer
Power damage, generates wafer chipping and wafer breakage；(2) scribing line width is larger, and crystal round utilization ratio is low；(3) scribing speed is slow, cutter
It is easy to wear；(4) it needs to consume a large amount of deionized waters when scribing to carry out blade cooling and rinse impurity, be easily destroyed in MEMS chip
Micro-structure.
On the contrary, laser cutting is noncontact procession, grooving is narrow, high degree of automation, in rate of cutting and to the not isomorphous
The applicability of disk, compatibility etc. have greater advantage, a kind of wafer laser cutting side as disclosed in CN 103537805A
Method.However, laser cutting cost is higher, and repeatedly cuts thicker MEMS wafer piece needs, during this
The molten bits generated are easy pollution chip, and MEMS chip is caused to fail.
Part invention carries out spin coating protection using photoresist in wafer front surface, carries out cutting through formula from the wafer back side and cut
It cuts, then using pallet with holes or gaily decorated basket auxiliary, cleaning removes photoresist in acetone, avoids clast in cutting process and falls into
In micro-structure.Such as CN 103086318A discloses a kind of MEMS silicon wafer scribing cutting and structure release method, this method
The step of include: to paste UV film in MEMS silicon wafer according to silicon wafer thickness the first time scribing of silicon wafer to be arranged
The thickness or knife up of second of scribing is set as needed in the knife up of thickness or saw blade；After the completion of scribing, UV film viscosity is eliminated
80%~90%, chip is picked up on UV film or removes whole silicon wafer and is placed in the pallet equipped with filter opening；Again by pallet
It is put into glue and removes photoresist, carry out de- liquid and dehydration and structure release later.This method solves thickness using scribing process twice
The problem that the spring side of large chip, the contamination of silicon bits, scribing cause chip internal stress big.CN203079678U then discloses above-mentioned pallet
Technical detail.
But the free standing structure films such as micro- heating dish, cantilever beam are especially contained in the MEMS chip of submillimeter level for size
In micro-meter scale, processing cost is high, it is difficult to effectively remove photoetching compound protective layer, clearly in hole in the chip of structure, pallet or the gaily decorated basket
It washes and is also easily destroyed free standing structure film structure in subsequent drying, drying chip processes.
Therefore, a kind of technology of effectively cutting MEMS wafer is developed, especially effectively cutting has micro- heating dish, cantilever beam
Etc. fragile structures wafer, had an important influence to packaging efficiency and product yield is improved.
Summary of the invention
In order to solve in the prior art using machine cuts and while being cut by laser to thicker wafer is difficult to avoid that
The problems such as chip surface damage, impurity pollution and fragment, utilizes back corrosion cutting MEMS silicon wafer the present invention provides a kind of
Method.The present invention is combined by dry method with wet corrosion technique, during having preparation MEMS silicon wafer, same to stepping
The back of row MEMS silicon wafer corrodes, and deeper back corrosion structure is formed at the MEMS silicon wafer back side, and MEMS chip side is thinned
The thickness of edge wafer；Optimization by carrying on the back corrosion structure eliminates machine cuts or laser cutting process, just for processing itself
It needs to reduce processing cost using the chip of back corrosion and improve product yield.
In order to achieve the above object, the invention adopts the following technical scheme:
The present invention provides a kind of method of back corrosion cutting MEMS silicon wafer, and the method is main are as follows: in MEMS silicon wafer
While the disk back side prepares heat-insulation chamber, back corrosion is carried out to MEMS silicon wafer and forms corrosion structure.
Heretofore described MEMS silicon wafer belongs to the prior art, and the MEMS silicon wafer is usual in the production process
It needs to be cut into MEMS chip one by one, these chips is then made into the different semiconductor package of function.General feelings
Under condition, front is chip core portion, passes sequentially through the preparations such as optical exposure and thin-film technique such as heating layer, oxygen from top to bottom
The structures such as compound insulating layer, interdigital electrode layer and gas sensitive material；Its back side needs to form heat-insulation chamber to reduce heat consumption
It dissipates, that is, reduces the power consumption of chip, and the formation of heat-insulation chamber needs to pass through back exposing and corrosion work at the back of MEMS silicon wafer
Skill removes the silicon below heating layer.Herein, no longer the detailed construction of MEMS silicon wafer is repeated.
After completing in prior art to MEMS silicon wafer, scribing is carried out using machine cuts and laser cutting,
There are many problems in scribing processes.And the present invention in order to avoid machine cuts and laser cutting process the problem of,
While preparing the heat-insulation chamber at the MEMS silicon wafer back side, back corrosion directly is carried out to MEMS silicon wafer and forms corrosion knot
Structure saves machine cuts or laser cutting parameter by the optimization to back corrosion structure, so that method of the invention has more preferably
Economy and convenience, implement simpler convenience, and processing cost can be reduced and improve product yield.
In the present invention, the MEMS silicon wafer for foring corrosion structure is encapsulated by the separation of subsequent sliver with welding to obtain the final product
Product.
It is used as currently preferred technical solution below, but not as the limitation of technical solution provided by the invention, passes through
Following technical scheme can preferably reach and realize technical purpose and beneficial effect of the invention.
As currently preferred technical solution, the MEMS silicon wafer is the MEMS Silicon Wafer that there is hanging structure on surface
Piece.
Preferably, the hanging structure is any one in membrane oscillation device, miniature gas-sensitive sensor or cantilever beam structure
Or at least two combination.But it is not limited to the above-mentioned hanging structure enumerated, other similar hanging structures commonly used in the art
It is suitable for the invention method.
Back corrosion cutting method of the present invention is not only applicable to conventional MEMS silicon wafer, is particularly suitable for table
There is the MEMS silicon wafer of hanging structure in face.
As currently preferred technical solution, the corrosion structure is the etching tank being arranged around heat-insulation chamber.
Preferably, the width of the etching tank is 10 μm~200 μm, such as 10 μm, 15 μm, 20 μm, 50 μm, 80 μm, 100
μm, 125 μm, 150 μm, 175 μm or 200 μm etc., it is not limited to cited numerical value, other are unlisted in the numberical range
Numerical value it is equally applicable.Herein, etching tank structure in a strip shape, width refer to the distance of etching tank short side.
Preferably, the corrosion structure includes lateral encroaching slot and longitudinal etching tank, lateral encroaching slot and longitudinal etching tank
Infall be not connected to.
Preferably, the infall of the lateral encroaching slot and longitudinal etching tank, between lateral encroaching slot and longitudinal etching tank
At least 10 μm of interval, preferably 10 μm~500 μm, such as 10 μm, 20 μm, 50 μm, 75 μm, 100 μm, 200 μm, 300 μm, 400 μ
M or 500 μm etc., it is not limited to cited numerical value, other interior unlisted numerical value of the numberical range are equally applicable.
Preferably, the depth of the etching tank is more than half of MEMS silicon wafer back side silicon wafer thickness.
In the present invention, the corrosion structure is arranged around heat-insulation chamber, ten formed between each corrosion structure
It is at least disconnected on one side in word structure, it can be not connected to, can also there is a line connection, if all connections, can make
There is excessive corroded area in later period wet etching course at right-angled intersection in corrosion structure, influences at subsequent sliver
Step is managed, or even destroys the structure of heat-insulation chamber, generates unfavorable result.
In the present invention, the depth of control corrosion rate structure reaches more than half of MEMS silicon wafer back side silicon wafer thickness, can be with
The thickness of MEMS chip edge wafer is thinned, is conducive to sliver technique and efficiently separates each wafer.
As currently preferred technical solution, the method is main are as follows: is carved at the MEMS silicon wafer back side using dry method
Erosion combines mode with wet etching, while preparing heat-insulation chamber and corrosion structure.
As currently preferred technical solution, the method specifically includes the following steps:
(1) optical exposure is carried out at the MEMS silicon wafer back side, development exposes corrosion slot structure cutting line；
(2) dry etching, removal MEMS silicon wafer back are carried out at the MEMS silicon wafer back side using photoresist as exposure mask
The composite layer in face, and silicon wafer is exposed, then remove photoresist；
(3) composite layer not removed using in step (2) by dry etching carries out the MEMS silicon wafer back side as exposure mask
Wet etching obtains heat-insulation chamber and corrosion structure.
Wherein, optical exposure and dry etching tentatively can define heat-insulation chamber and corrosion knot at the MEMS silicon wafer back side
Structure ensures going on smoothly for wet etching；Wet etching can remove exposed silicon layer, further obtain required heat-insulation chamber and
Corrosion structure.Method of the invention designs back corrosion structure around each MEMS chip, and dry etching and wet process are carved
Erosion organically combines, and deeper etching tank can be formed at the back side of MEMS silicon wafer chip, is thinned MEMS chip edge crystalline substance
Round thickness.As currently preferred technical solution, the silicon layer in step (1) the MEMS silicon wafer is twin polishing
Monocrystalline silicon piece, with a thickness of 200 μm~1000 μm, such as 200 μm, 380 μm, 520 μm, 670 μm, 750 μm or 1000 μm etc.,
It is not limited to cited numerical value, other interior unlisted numerical value of the numberical range are equally applicable；Crystal orientation is<100>.
Preferably, the two sides of the silicon layer in step (1) the MEMS silicon wafer is equipped with composite layer.
Preferably, the composite layer is silica and/or silicon nitride.It is described " silica and/or silicon nitride " in the present invention
Refer to: can be silica, can be silicon nitride, or silica and silicon nitride.
Preferably, the composite layer with a thickness of 50nm~5000nm, such as 50nm, 100nm, 200nm, 500nm,
800nm, 1000nm, 2000nm, 3000nm, 4000nm or 5000nm etc., it is not limited to cited numerical value, the numerical value model
Other unlisted numerical value are equally applicable in enclosing.
As currently preferred technical solution, with photoresist and with corrosion structure in step (1) described optical exposure
Mask plate the MEMS silicon wafer back side carry out optical exposure.
As currently preferred technical solution, step (2) the dry etching using plasma etching, wherein used
Etchant gas is sulfur hexafluoride and/or fluoroform；
In the present invention, " sulfur hexafluoride and/or the fluoroform " refers to: can be sulfur hexafluoride, can be fluoroform
Alkane, or sulfur hexafluoride and fluoroform.
In the present invention, etchant gas used is not limited in sulfur hexafluoride and/or fluoroform in plasma etch process
Alkane, other same gases up to etching effect are equally applicable to the present invention.
Preferably, deep silicon etching, the silicon layer of 10 μm~300 μm of removal, example are used while step (2) described dry etching
Such as 10 μm, 30 μm, 60 μm, 80 μm, 100 μm, 150 μm, 200 μm, 250 μm or 300 μm of silicon layer, it is not limited to listed
The numerical value of act, other interior unlisted numerical value of the numberical range are equally applicable.Herein, the deep silicon etching is in the prior art
There is method, belongs to clear statement.
As currently preferred technical solution, wet etching described in step (3) is to be corroded using alkaline solution.
Preferably, the alkaline solution is the aqueous solution of potassium hydroxide solution or ethylenediamine and catechol.
Preferably, the solvent in the potassium hydroxide solution is the mixture of water and/or water and isopropanol.
Preferably, concentration 20wt%~35wt% of the potassium hydroxide solution, for example, 20wt%, 25wt%, 30wt%,
32wt% or 35wt% etc., it is not limited to cited numerical value, other interior unlisted numerical value of the numberical range are equally suitable
With.
Preferably, when the alkaline solution is potassium hydroxide solution, the temperature of wet etching is 75 DEG C~80 DEG C, such as
75 DEG C, 76 DEG C, 77 DEG C, 78 DEG C, 79 DEG C or 80 DEG C etc., it is not limited to cited numerical value, in the numberical range, other are not
The numerical value enumerated is equally applicable.
Preferably, the molar ratio of ethylenediamine, catechol and water is 35 in the aqueous solution of the ethylenediamine and catechol:
4:61。
Preferably, when the alkaline solution is the aqueous solution of ethylenediamine and catechol, the temperature of corrosion is 115 DEG C.
Preferably, the time of the wet etching be 2h~6h, such as 2h, 3h, 4h, 4.5h, 5h, 5.5h or 6h etc., but
It is not limited in cited numerical value, other unlisted numerical value are equally applicable in the numberical range.
As currently preferred technical solution, the MEMS silicon wafer after back corrosion cutting is separated and is welded through sliver
MEMS chip product is obtained after encapsulation.
The beneficial effects of the present invention are:
(1) in the method for the invention, back etching tank is prepared with heat-insulation chamber by identical technical process simultaneously, is implemented
Back corrosion structure need to be only added in journey on back exposing mask plate, there is better economy and convenience, drop product cost
Low 1%；
(2) infall of the method for the invention lateral encroaching slot and longitudinal etching tank has interval, is not connected to, this to carve
The part of eating away is more accurate, avoid etching it is excessive caused by MEMS silicon wafer fault of construction, subsequent processing will not be made
At adverse effect, product yield is made to reach 100%；
(3) the method for the invention effectively prevents the surface damage generated in machine cuts and laser cutting process, broken
The problems such as bits pollution, high yield rate；Specifically, method of the invention does not use machine cuts, avoids mechanical cutting procedure
The damage of middle vibration cutting and water impact to micro-structures such as electrode, oxide layer, hanging layers；Reduce laser cutting process, keeps away
Exempt from that laser cutting bring process is long, pollution is generated to wafer in problem and laser cutting process at high cost.
Detailed description of the invention
Fig. 1 is the structural profile illustration of MEMS silicon wafer described in the embodiment of the present invention 1；
Fig. 2 is the floor map that corrosion structure is carried on the back described in the embodiment of the present invention 1；
Fig. 3 is the floor map that corrosion structure is carried on the back described in the embodiment of the present invention 2；
Wherein 1- heat-insulation chamber, 2- silicon nitride dielectric layer, 3- monocrystalline substrate, 4- heat electrode, 5- oxide insulating layer, 6-
Interdigital electrode layer, 7- gas sensitive material layer, 8- carry on the back etching tank.
Specific embodiment
In order to better illustrate the present invention, it is easy to understand technical solution of the present invention, below further specifically to the present invention
It is bright.But following embodiments is only simple example of the invention, does not represent or limit the scope of the present invention, this
Invention protection scope is subject to claims.
A specific embodiment of the invention part provides a kind of method of back corrosion cutting MEMS silicon wafer, the side
Method is main are as follows: while the MEMS silicon wafer back side prepares heat-insulation chamber 1, carries out back corrosion to MEMS silicon wafer and forms corrosion
Structure, the corrosion structure are the etching tank being arranged around heat-insulation chamber.
The method specifically includes the following steps:
(1) optical exposure is carried out at the MEMS silicon wafer back side, development exposes corrosion slot structure cutting line；
(2) dry etching, removal MEMS silicon wafer back are carried out at the MEMS silicon wafer back side using photoresist as exposure mask
The composite layer in face, and silicon wafer is exposed, then remove photoresist；
(3) composite layer not removed using in step (2) by dry etching carries out the MEMS silicon wafer back side as exposure mask
Wet etching obtains heat-insulation chamber 1 and corrosion structure.
The following are typical but non-limiting embodiments of the invention:
Embodiment 1:
A kind of method for present embodiments providing back corrosion cutting MEMS silicon wafer, the MEMS Silicon Wafer to be cut
The structure of piece is as shown in Figure 1, it is a kind of miniature gas-sensitive sensor chip, and the chip manufacturing is in the twin polishing of 400 μ m-thicks
On silicon nitride/silicon<100>wafer, wafer frontside is chip core portion, and silicon nitride dielectric layer 2 is coated in monocrystalline substrate 3,
Then heating electrode 4, oxide have been sequentially prepared by optical exposure and thin-film technique from the bottom up on silicon nitride dielectric layer 2
Insulating layer 5, interdigital electrode layer 6 and gas sensitive material 7.In the present embodiment, oxide insulating layer 5 is chemical vapor deposition skill
The silica of the 200nm thickness of art preparation, silicon nitride dielectric layer 2 are 300nm thick, and interdigital electrode layer 6 is usually the gold of 100nm thickness
Electrode material, gas sensitive material layer 7 are the doping SnO of the 100nm thickness of magnetron sputtering technique preparation2Film.In order to reduce heat
Amount dissipates, that is, reduces the power consumption of chip, and wafer back part needs to remove the silicon below heating layer, shape by back exposing and etching process
At 1 structure of heat-insulation chamber in Fig. 1.
The present embodiment carries out back corrosion cutting at the back side of above-mentioned MEMS silicon wafer, and specific implementation method includes following step
It is rapid:
(1) the back Chemically etching stencils with back corrosion structure cutting line are overlie into the MEMS silicon wafer back side to be cut,
Back corrosion structure cutting line as shown in Figure 2 is formed in each chip surrounding, the cutting line line width for carrying on the back corrosion structure is 50 μm,
50 μm are divided between middle transverse cut and longitudinally cutting line；Then back exposing is carried out in backside of wafer, development exposes nitrogen
Cutting line on SiClx layer；
(2) using photoresist as exposure mask, remove the 300nm that backside of wafer is not photo-etched glue protection using dry etch process
Thick silicon nitride and 200 μm of silicon, finally carries out uv-exposure for photoresist, and clean removal with acetone；
(3) wafer after dry etching is fixed with polytetrafluoro fixture, positive chip structure is protected in fixture
Portion；Backside of wafer to be corroded is exposed, using not by dry etching remove composite layer be used as exposure mask, using concentration be 30%
The potassium hydroxide solution of wt takes out after carrying out backside of wafer wet etching 2.5h at 75-80 DEG C, with deionized water and anhydrous second
Alcohol cleaning wafer piece, obtains the MEMS silicon wafer with etching tank 8, and structure is as shown in Figure 1.The top of the etching tank 8 away from
Still there are 50 μm from upper silicon nitride insulating layer.Its plan structure as shown in Fig. 2, Fig. 2 illustrates 4 adjacent MEMS chip units,
The square area of center 0.8mm × 0.8mm is heat-insulation chamber 1, and surrounding rectangular area is the corrosion structure that etching tank 8 is formed.
After MEMS silicon wafer after back corrosion cutting carries out wafer sliver using ultraviolet sensitivity film, product yield
100%, this saves laser cutting process in the process.
Embodiment 2:
A kind of method for present embodiments providing back corrosion cutting MEMS silicon wafer, specific implementation step is referring to embodiment
1, difference is, back corrosion structure in step (1) is as shown in figure 3, be formed by back corrosion structure cutting line, back corrosion structure
100 μm of cutting line line width, and be independently, between transverse cut and longitudinally cutting line between be divided into 100 μm.
The present embodiment obtains the MEMS silicon wafer with etching tank 8, and structure is as shown in Figure 1, its plan structure such as Fig. 3
Shown, Fig. 3 illustrates 4 adjacent MEMS chip units, and the square area of center 0.8mm × 0.8mm is heat-insulation chamber 1, surrounding
Rectangular area is the corrosion structure that etching tank 8 is formed.
After MEMS silicon wafer after back corrosion cutting carries out wafer sliver using ultraviolet sensitivity film, product yield
100%, this saves laser cutting process in the process.
The skeleton that the embodiment completes whole wafer after back corrodes is stronger, the fragment when back corrosion is finished and cleaned
Probability it is lower, be suitble to larger-size wafer.
Embodiment 3:
A kind of method for present embodiments providing back corrosion cutting MEMS silicon wafer, the MEMS Silicon Wafer to be cut
The structure of MEMS silicon wafer to be cut, difference are in the structure reference embodiment 1 of piece: the chip manufacturing is in 670 μ m-thicks
Twin polishing silicon nitride/silicon<100>wafer on, oxide insulating layer 5 is that the 50nm of chemical vapour deposition technique preparation is thick
Silica, silicon nitride dielectric layer 2 are 50nm thick.
Referring to embodiment 1, difference is the back corrosion cutting method: the back corrosion structure cutting formed in step (1)
In line cutting line line width be 10 μm, between transverse cut and longitudinally cutting line between be divided into 10 μm；
Wet etching uses concentration to carry out wet etching 5h at 80 DEG C for the KOH aqueous solution of 25wt% in step (3)；
The top of etching tank formed in the present embodiment still has 170 μm apart from upper silicon nitride insulating layer.
After MEMS silicon wafer after back corrosion cutting carries out wafer sliver using ultraviolet sensitivity film, product yield
100%, this saves laser cutting process in the process.
The skeleton that the embodiment completes whole wafer after back corrodes is stronger, the fragment when back corrosion is finished and cleaned
Probability it is lower, be suitble to larger-size wafer.
Embodiment 4:
A kind of method for present embodiments providing back corrosion cutting MEMS silicon wafer, the MEMS Silicon Wafer to be cut
Structure of the structure of piece referring to MEMS silicon wafer to be cut in embodiment 1.
Referring to embodiment 1, difference is the back corrosion cutting method: the back corrosion structure cutting formed in step (1)
In line cutting line line width be 200 μm, between transverse cut and longitudinally cutting line between be divided into 200 μm；
Wet etching liquid is that the aqueous solution (three's molar ratio is 35:4:61) of ethylenediamine and catechol exists in step (3)
Wet etching 2h is carried out at 115 DEG C；
The top of etching tank formed in the present embodiment still has 80 μm apart from upper silicon nitride insulating layer.
After MEMS silicon wafer after back corrosion cutting carries out wafer sliver using ultraviolet sensitivity film, product yield
100%, this saves laser cutting process in the process.
The skeleton that the embodiment completes whole wafer after back corrodes is stronger, the fragment when back corrosion is finished and cleaned
Probability it is lower, be suitble to larger-size wafer.
Comparative example 1:
This comparative example provides a kind of method for cutting MEMS silicon wafer, the wafer to be cut used and embodiment 1
Identical, difference is: without back corrosion cutting, and machine cuts being used to carry out scribing.
This comparative example, vibration cutting and water impact cause interdigital electrode large area to fall off in mechanical cutting procedure, every
Micro-structure on hot chamber is also crushed mostly, and final products yield is 0%.
Comparative example 2:
This comparative example provides a kind of method for cutting MEMS silicon wafer, the wafer to be cut used and embodiment 1
Identical, difference is: without back corrosion cutting, and laser cutting being used to carry out scribing.
This comparative example reaches 100% although laser cutting success rate is higher, and laser cutting, process is repeated several times
It is long, it is at high cost.
Comparative example 3:
This comparative example provides a kind of method for cutting MEMS silicon wafer, the wafer to be cut used and embodiment 1
Identical, specific steps reference implementation example 1, difference is: step connects between transverse cut and longitudinally cutting line in (1).
As a result: transverse cut and the intersection of longitudinally cutting line generate large area corrosion, destroy hanging structure,
Yield 0%.It can be seen that the method that embodiment uses cutting crystal wafer of the present invention with comparative example based on the above embodiments,
Mode is combined with wet etching using dry etching at the MEMS silicon wafer back side, while preparing heat-insulation chamber and corrosion structure,
And the infall of lateral encroaching slot and longitudinal etching tank is not connected to, and is reduced processing cost and is improved product yield, in table
Face, which has, shows splendid applicability on the MEMS chip of hanging structure；Comparative example 1 and comparative example 2 be not using of the present invention
Back corrosion cutting MEMS silicon wafer method, cause the decline of yields or the raising of processing cost, comparative example 3 does not have
Having is not connected to lateral encroaching slot and the infall of longitudinal etching tank, is equally unable to reach Gao Liang caused by method of the invention
The effect of product rate.
The Applicant declares that the present invention is explained by the above embodiments detailed process equipment and process flow of the invention,
But the present invention is not limited to the above detailed process equipment and process flow, that is, it is above-mentioned detailed not mean that the present invention must rely on
Process equipment and process flow could be implemented.It should be clear to those skilled in the art, any improvement in the present invention,
Addition, selection of concrete mode of equivalence replacement and auxiliary element to each raw material of product of the present invention etc., all fall within of the invention
Within protection scope and the open scope.
Claims (10)
1. a kind of method of back corrosion cutting MEMS silicon wafer, which is characterized in that the method is main are as follows: in MEMS Silicon Wafer
While the piece back side prepares heat-insulation chamber, back corrosion is carried out to MEMS silicon wafer and forms corrosion structure.
2. the method according to claim 1, wherein the MEMS silicon wafer is that surface has hanging structure
MEMS silicon wafer；
Preferably, the hanging structure be membrane oscillation device, miniature gas-sensitive sensor or cantilever beam structure in any one or extremely
Few two kinds of combination.
3. method according to claim 1 or 2, which is characterized in that the corrosion structure is the corruption being arranged around heat-insulation chamber
Lose slot；
Preferably, the width of the etching tank is 10 μm~200 μm；
Preferably, the corrosion structure includes lateral encroaching slot and longitudinal etching tank, the friendship of lateral encroaching slot and longitudinal etching tank
It is not connected at fork；
Preferably, the infall of the lateral encroaching slot and longitudinal etching tank is spaced between lateral encroaching slot and longitudinal etching tank
At least 10 μm, preferably 10 μm~500 μm；
Preferably, the depth of the etching tank is more than half of MEMS silicon wafer back side silicon wafer thickness.
4. method according to claim 1-3, which is characterized in that the method is main are as follows: in MEMS Silicon Wafer
The piece back side combines mode with wet etching using dry etching, while preparing heat-insulation chamber and corrosion structure.
5. method according to claim 1-4, which is characterized in that the method specifically includes the following steps:
(1) optical exposure is carried out at the MEMS silicon wafer back side, development exposes corrosion slot structure cutting line；
(2) dry etching is carried out at the MEMS silicon wafer back side using photoresist as exposure mask, the removal MEMS silicon wafer back side
Composite layer, and silicon wafer is exposed, then remove photoresist；
(3) composite layer not removed using in step (2) by dry etching carries out wet process to the MEMS silicon wafer back side as exposure mask
Corrosion, obtains heat-insulation chamber and corrosion structure.
6. according to the method described in claim 5, it is characterized in that, the silicon layer in step (1) the MEMS silicon wafer is double
The monocrystalline silicon piece of face polishing, with a thickness of 200 μm~1000 μm, crystal orientation is<100>；
Preferably, the two sides of the silicon layer in step (1) the MEMS silicon wafer is equipped with composite layer；
Preferably, the composite layer is silica and/or silicon nitride；
Preferably, the composite layer with a thickness of 50nm~5000nm.
7. method according to claim 5 or 6, which is characterized in that with photoresist and band in step (1) described optical exposure
There is the mask plate of corrosion structure to carry out optical exposure at the MEMS silicon wafer back side.
8. according to the described in any item methods of claim 5-7, which is characterized in that step (2) dry etching using etc. from
Daughter etching, wherein etchant gas used is sulfur hexafluoride and/or fluoroform；
Preferably, deep silicon etching, the silicon layer of 10 μm~300 μm of removal are used while step (2) described dry etching.
9. according to the described in any item methods of claim 5-8, which is characterized in that wet etching described in step (3) is to use
Alkaline solution is corroded；
Preferably, the alkaline solution is the aqueous solution of potassium hydroxide solution or ethylenediamine and catechol；
Preferably, the solvent in the potassium hydroxide solution is the mixture of water and/or water and isopropanol；
Preferably, concentration 20wt%~35wt% of the potassium hydroxide solution；
Preferably, when the alkaline solution is potassium hydroxide solution, the temperature of corrosion is 75 DEG C~80 DEG C；
Preferably, the molar ratio of ethylenediamine, catechol and water is 35:4 in the aqueous solution of the ethylenediamine and catechol:
61；
Preferably, when the alkaline solution is the aqueous solution of ethylenediamine and catechol, the temperature of corrosion is 115 DEG C；
Preferably, the time of the wet etching is 2h~6h.
10. -9 described in any item methods according to claim 1, which is characterized in that the MEMS Silicon Wafer after back corrosion cutting
Piece separates through sliver and obtains MEMS chip product with after welding encapsulation.
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