CN100579893C - Centrifugal separating sacrificial layer process - Google Patents
Centrifugal separating sacrificial layer process Download PDFInfo
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- CN100579893C CN100579893C CN200510086892A CN200510086892A CN100579893C CN 100579893 C CN100579893 C CN 100579893C CN 200510086892 A CN200510086892 A CN 200510086892A CN 200510086892 A CN200510086892 A CN 200510086892A CN 100579893 C CN100579893 C CN 100579893C
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Abstract
A process for centrifugal separation of sacrificial layer includes such steps as washing substrate, coating sacrifical layer, spinning coating of photoresist, photoetching, using acetone to remove photoresist layer, spinning coating of photoresist, photoetching, developing to remove sacrificial layer and generating film bridge and cantilever structure, and centrifugal separation for removing the liquid from the surface of substrate and releasing microstructure.
Description
Technical field
The present invention relates to the preparation method of micro-structural in the MEMS technology, relate in particular to a kind of centrifugal separating victim layer process.
Technical background
Sacrificial layer technology also claims the separating layer technology, utilize the greatest differences of different materials corrosion rate in same corrosive liquid exactly, to optionally remove by the one deck in definite shape and the multilayered film material that is superimposed of order, thereby obtain required structure, this one deck that wherein is removed is called as sacrifice layer.According to the difference of sacrifice layer removal method, sacrificial layer technology mainly is divided into dry etching sacrificial layer technology and wet etching sacrificial layer technology.
The dry etching sacrificial layer technology is exactly that method with gaseous state corrosion or plasma etching removes sacrifice layer.For example adopt gaseous state HF and methyl alcohol to remove SiO
2Sacrifice layer; Use O
2Organic material sacrifice layers such as plasma removal photoresist etc.Though there is not the problem that makes structural failure owing to surface tension in the dry etching sacrificial layer technology, exist etching time longer, cause substrate surface damage easily and stain; Need on hanging structure, do a series of aperture and come releasing sacrificial layer, thus the integrality of destruction drives structure; The sacrificial layer material overwhelming majority is the organic sacrificing layer material, and promptly sacrifice layer is alternative poor; Equipment has limited its further range of application usually than problems such as costlinesses.
The wet etching sacrificial layer technology is exactly to utilize some sacrificial layer material to dissolve in specific solvent or corrosive liquid, and the masking layer material is insoluble to the characteristic of this solvent or corrosive liquid substantially, removes sacrifice layer.For example can remove with acetone as the photoresist of sacrifice layer; Polyimides (when bake out temperature is usually less than 200 ℃) can be removed with alkaline-based developer; Oxidized porous silicon and silicon phosphorus glass PSG can use HF solution removal etc.Wet etching sacrificial layer technology speed is very fast and be difficult for causing substrate surface to pollute, but because the influence of solution surface tension in the liquid drying process, makes drives structure and substrate adhesion easily, causes micro-structural to lose efficacy.Therefore, drives structure can not lost efficacy because of surperficial adhesion or fracture, become the key of wet etching sacrificial layer technology, proposed at present to solve surperficial adhesion problems as the whole bag of tricks such as critical point mummification method, multi-solvent mummification method, geometry in particular methods, though above-mentioned several separation method can reach the effect of separation, problem such as all life period is long, technology is complicated and yield rate is low.
Summary of the invention
Technology of the present invention is dealt with problems and is: the weak point at above removal sacrifice layer method, a kind of centrifugal separating victim layer process is proposed, and this method utilizes centrifugal force to solve surperficial bonding problem, and has that technology is simple, the time is short, the finished product advantages of higher.
Technical solution of the present invention is: a kind of centrifugal separating victim layer process, it is characterized in that: by the rotating speed of control centrifuge, centrifugal force controlled can either overcome drop-down surface tension of liquid, simultaneously be unlikely to destroy between the micro-structurals such as air film bridge or cantilever beam again, reach removal liquid, discharge the purpose of micro-structural, its concrete steps are as follows:
(1) substrate cleans;
Clean monocrystalline silicon substrate with HF solution, deionized water and acetone+ethanolic solution respectively, then substrate is put into drying in oven;
(2) sacrifice layer applies;
On substrate, apply sacrifice layer, at first, on substrate, be coated with tackifier; Then, dry behind the spin-on polyimide sacrifice layer, the thickness of oven dry back polyimide sacrificial layer is 2-3 μ m;
(3) photoresist of spin coating for the first time;
Apply photoresist layer on polyimide sacrificial layer, photoresist layer thickness is 5-7 μ m;
(4) carry out the photoetching first time;
On described photoresist layer, adopt the mask version to make the anchor position figure of cantilever beam or film bridge by lithography;
(5) acetone is removed photoresist;
Adopt the photoresist layer on the acetone removal sacrifice layer, polyimides is insoluble to acetone, and remains;
(6) photoresist of spin coating for the second time;
Apply one deck photoresist on polyimide sacrificial layer again, photoresist layer thickness is 3-5 μ m;
(7) carry out the photoetching second time;
On the photoresist of the spin coating second time, adopt the mask version to carry out the exposure second time, etch away the part outside cantilever beam and the film bridge figure, form the cantilever beam and the film bridge construction of photoresist;
(8) sacrifice layer is removed in development;
Because polyimide sacrificial layer is dissolved in alkaline-based developer, and the photoresist of bridge unexposed portion is insoluble to alkaline-based developer, thereby form film bridge and cantilever beam structures at developer solution;
(9) centrifugation;
The good substrate of rinsing in deionized water is taken out, with its back side with being fixed on the work stage; Then work stage is placed on the centrifuge,, removes the liquid of substrate surface, make micro-structural obtain discharging by the rotating speed 1400rpm-1600rpm of control centrifuge.
The present invention is with the advantage of the comparison of prior art: the present invention compares with other wet separation technologies such as critical point mummification method, multi-solvent mummification method, geometry in particular methods, centrifugal separating victim layer process can in minutes reach separating effect, and can not damaging, and less demanding to equipment to isolating construction.Therefore this technology has fast, and simple to operate, characteristics such as yield rate height have great practical value.In addition, the present invention makes the micro-structurals such as film bridge and cantilever beam except that being applied to, and also can be applicable to make other micromechanics drives structure, has very high practical value.
Description of drawings
Fig. 1 is a 1# mask version schematic diagram of the present invention, is used for photoetching for the first time, and the shadow region is light tight district among Fig. 1, and white portion is a transparent area;
Fig. 2 is a 2# mask version schematic diagram of the present invention, is used for photoetching for the second time, will etch away part outside cantilever beam and the film bridge figure with this piece mask exposure, forms the cantilever beam and the film bridge knot of photoresist, and 1 is the air film bridge construction among Fig. 2, and 2 is cantilever beam structures;
Fig. 3 is the schematic diagram of step of the present invention (2), i.e. spin coating one deck polyimide sacrificial layer 3 on cleaned silicon chip surface;
Fig. 4 is the schematic diagram of step of the present invention (3), promptly applies photoresist layer 4 on sacrifice layer;
Fig. 5 promptly carries out the photoetching first time for the schematic diagram of step of the present invention (4), the anchor position 6 of on silicon chip, come out air film bridge 5 and cantilever beam, and the position of arrow indication is exactly the anchor position among the figure;
Fig. 6 is the schematic diagram of step of the present invention (5), and promptly acetone is removed the photoresist on the sacrifice layer, and polyimide sacrificial layer is insoluble to acetone, and remains;
Fig. 7 is the schematic diagram of step of the present invention (6), i.e. spin coating one deck photoresist 7 again on polyimide sacrificial layer;
Fig. 8 is the schematic diagram of step of the present invention (7) and step (8), promptly with the exposure of 2# mask version, develops and removes sacrifice layer.Because polyimide sacrificial layer is dissolved in alkaline-based developer, and the photoresist of bridge unexposed portion is insoluble to alkaline-based developer, form film bridge 8 and cantilever beam structures 9;
Fig. 9 promptly by centrifugation, makes that air film bridge 10 and cantilever beam 11 micro-structurals are unsettled for the schematic diagram of step of the present invention (9);
Figure 10 is the schematic diagram of the centrifugal separating device of the present invention's employing, and wherein 12 is that work stage, 13 is that centrifuge, 14 is substrate, and the centrifuge that is used for centrifugation should be furnished with vacuum system, work stage can be inhaled on centrifuge during work;
Figure 11 is the integrally-built SEM photo of cantilever beam of the present invention;
Figure 12 is the SEM photo of air film bridge construction of the present invention, and length is 200 μ m;
Figure 13 is the optical microscope photograph of air film bridge construction of the present invention, and length is 400 μ m;
Figure 14 is the optical microscope photograph of cantilever beam structures of the present invention;
Figure 15 is air film bridge construction of the present invention optical microscope photograph during with the substrate surface adhesion under the surface tension of liquid effect.
The specific embodiment
An exemplary embodiments of the present invention is to utilize centrifugal separating victim layer process to make photoresist air film bridge and cantilever beam micro-structural, and its manufacturing process is as follows:
(1) substrate cleans
The purpose that substrate cleans is in order to remove the various organic and inorganic impurity of substrate surface, to strengthen the adhesion of photoresist and sacrifice layer and substrate surface, improving yield rate.
The first step with the oxide layer on 10%HF flush away monocrystalline silicon substrate surface, uses deionized water (resistivity 〉=16M Ω) ultrasonic wave to clean 15min again; Second step, substrate is cleaned with acetone+ethanolic solution on centrifuge, dry; The 3rd step, substrate is put into baking oven, dry by the fire 120min under 170 ℃ of temperature.
(2) sacrifice layer applies
On substrate, apply sacrifice layer.At first on substrate, be coated with tackifier, to increase the adhesive force of substrate surface and polyimides, the glue phenomenon that contracts of polyimides when alleviating drying glue; Spin-on polyimide again, drying time 100s under 100 ℃ of temperature on the hot plate puts into baking oven again, dries by the fire 30min under 170 ℃ of temperature.The about 2.5 μ m of the thickness of polyimide sacrificial layer 3, as shown in Figure 3.
(3) spin coating photoresist
On sacrifice layer, apply photoresist layer 4, the about 6.0 μ m of photoresist layer thickness, drying time 120s under 100 ℃ of temperature on the hot plate, as shown in Figure 4.
(4) photoetching for the first time
1# mask version is used for photoetching for the first time, and will expose on sacrifice layer and photoresist layer with this piece mask etches the anchor position of cantilever beam and film bridge, its domain as shown in Figure 1, the shadow region is light tight district among the figure, white portion is a transparent area.The transparent area on the left side is divided into a plurality of rectangular shapes, and the transparent area on the right is the elongate in shape that fuses.To make the anchor position at each transparent area, between left transparent area and right transparent area, set up the film bridge again, set up cantilever beam on right transparent area the right, as shown in Figure 2, each left transparent area is different with distance between the right transparent area, is in order to make the different film bridge of a plurality of length simultaneously.
On photoresist layer, carve the anchor position figure.Adopt as shown in Figure 1 the 1# mask version 48s that on photoresist, exposes, in 303A (1: 6) alkaline-based developer, develop under the room temperature.Positive photoresist is subjected to UV-irradiation after exposure that part of photoresist can be dissolved in developer solution owing to photochemical reaction is degraded, and the photoresist that is not subjected to UV-irradiation can not be dissolved in developer solution.Like this; positive photoresist exposed portion and following sacrifice layer thereof will be dissolved in developer solution respectively; and the photoresist of unexposed portion will protect it to be insoluble to developer solution as masking layer on the sacrifice layer 3; thereby the Micropicture of 1# mask version is delivered to polyimide sacrificial layer 3; after exposure, the development; make the film bridge on the part that stays in the centre, remove on the position of exposing substrate on both sides and make the anchor position.As shown in Figure 5, the position that silicon chip comes out among the figure is exactly the anchor position 6 of film bridge 5 and cantilever beam.
(5) acetone is removed photoresist
Acetone is removed the photoresist on the sacrifice layer, and polyimide sacrificial layer is insoluble to acetone, and remains, as shown in Figure 6.
(6) spin coating photoresist
Apply one deck photoresist 7 again in the zone that makes film bridge and anchor position.Spin coating AZ9260 positive photoresist is put into hot plate, dries by the fire 3min under 120 ℃ of temperature.Photoresist layer 4 thickness are 6.4 μ m, and the photoresist layer thickness on polyimide sacrificial layer is about 4 μ m, as shown in Figure 7.
(7) photoetching for the second time
With 2# mask version exposure 48s, as shown in Figure 8, the zone among the figure outside film bridge and the cantilever beam figure is an exposure region.
2# mask version is used for photoetching for the second time, will etch away part outside cantilever beam and the film bridge figure with this mask exposure, forms the film bridge and the cantilever beam structures of photoresist, and its domain as shown in Figure 2.The shadow region is light tight district among the figure, and white portion is a transparent area.Wherein the little figure in the left side is the enlarged drawing of film bridge construction, and the tiny shadow region of arrow indication is the film bridge among the figure, and bigger shadow region, two ends is the anchor position of film bridge; The little figure in the right is the enlarged drawing of cantilever beam structures, and the shadow region of arrow indication is cantilever beam among the figure, and bigger shadow region, the left side is the anchor position of cantilever beam.2# mask version has designed the different film bridge figure of several length, also is in order to make the film bridge of a plurality of different sizes simultaneously in experiment.
(8) sacrifice layer is removed in development
About 180s that develops in 303A (1: 6) developer solution under the room temperature puts it into rinsing in the deionized water again.Because polyimide sacrificial layer is dissolved in alkaline-based developer, and the photoresist of bridge unexposed portion is insoluble to alkaline-based developer, form film bridge and cantilever beam structures, as shown in Figure 8.
(9) centrifugation
At first the substrate behind the removal sacrifice layer is put into the careful rinsing of deionized water, take out substrate afterwards, substrate back is sticked on the work stage with double faced adhesive tape, then work stage is placed on the centrifuge, centrifuge dripping is removed liquid, discharges micro-structural.As shown in Figure 9.
As shown in figure 10, centrifugal separating device of the present invention is made up of work stage 12, centrifuge 13, substrate 14, and the radius of turn of work stage 12 is about 20mm, and the rotating speed of centrifuge is 1400-1600rpm, about 3～4min of the time of centrifuge dripping.
By the present embodiment card, utilize centrifugal separating victim layer process to make photoresist air film bridge and cantilever beam structures.The thickness of air film bridge 10 and cantilever beam hanging structure 11 is all about 4 μ m, and wherein the length of cantilever beam is about 150 μ m, and the length of air film bridge can have three kinds of 200 μ m, 300 μ m and 400 μ m.
As Figure 11-shown in Figure 15, by SEM (SEM) photo and optical microscope photograph, can find out obviously that the photoresist film bridge and the cantilever beam structures that adopt centrifugal separating victim layer process to prepare are complete, do not stick together with substrate.Wherein Figure 11 and Figure 12 figure are respectively the SEM photo of cantilever beam overall structure of the present invention and air film bridge construction, and the marginal portion that can be clear that air film bridge and cantilever beam among the figure is fully unsettled.Owing to can only see whether the edge of micro-structural is unsettled in the SEM photo, can't observe whether the micro-structural the inside also is unsettled, therefore need judge whether isolating construction is unsettled in conjunction with optical microscope photograph.Figure 13 and Figure 14 are respectively unsettled air film bridge and cantilever beam optical microscope photograph fully, Figure 15 is the unsettled air film bridge optical microscope photograph of part, relatively Figure 13, Figure 14 and Figure 15 can obviously see the air film bridge construction chromatic colour interference fringe that part is unsettled, and unsettled air film bridge and cantilever beam structures do not have interference fringe fully.
Claims (1)
1, a kind of centrifugal separating victim layer process is characterized in that concrete steps are as follows:
(1) substrate cleans
Clean monocrystalline silicon substrate with HF solution, deionized water and acetone+ethanolic solution respectively, then substrate is put into drying in oven;
(2) sacrifice layer applies
On substrate, apply sacrifice layer, at first, on substrate, be coated with tackifier; Then, dry behind the spin-on polyimide sacrifice layer, the thickness of oven dry back polyimide sacrificial layer is 2-3 μ m;
(3) photoresist of spin coating for the first time
Apply photoresist layer on polyimide sacrificial layer, photoresist layer thickness is 5-7 μ m;
(4) carry out the photoetching first time
On described photoresist layer, adopt the mask version to make the anchor position figure of cantilever beam or film bridge by lithography;
(5) acetone is removed photoresist
Adopt the photoresist layer on the acetone removal sacrifice layer, polyimides is insoluble to acetone, and remains;
(6) photoresist of spin coating for the second time
Apply one deck photoresist on polyimide sacrificial layer again, photoresist layer thickness is 3-5 μ m;
(7) carry out the photoetching second time
On the photoresist of the spin coating second time, adopt the mask version to carry out the exposure second time, etch away the part outside cantilever beam and the film bridge figure, form the cantilever beam and the film bridge construction of photoresist;
(8) sacrifice layer is removed in development
Polyimide sacrificial layer is dissolved in alkaline-based developer, and the photoresist of bridge unexposed portion is insoluble to alkaline-based developer, thereby forms film bridge and cantilever beam structures at developer solution;
(9) centrifugation
The substrate good rinsing in deionized water takes out, and its back side is fixed on the work stage; Then work stage is placed on the centrifuge,, removes the liquid of substrate surface, make micro-structural obtain discharging by the rotating speed 1400rpm-1600rpm of control centrifuge.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN200510086892A CN100579893C (en) | 2005-11-17 | 2005-11-17 | Centrifugal separating sacrificial layer process |
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| CN200510086892A CN100579893C (en) | 2005-11-17 | 2005-11-17 | Centrifugal separating sacrificial layer process |
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| CN1817781A CN1817781A (en) | 2006-08-16 |
| CN100579893C true CN100579893C (en) | 2010-01-13 |
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| CN109279572A (en) * | 2018-11-19 | 2019-01-29 | 中国科学技术大学 | Superconductor Vacuum bridge and preparation method thereof |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1211064A (en) * | 1998-07-03 | 1999-03-17 | 北京大学 | Polysilicon structure discharge technology for surface treatment |
| US6331257B1 (en) * | 1998-05-15 | 2001-12-18 | Hughes Electronics Corporation | Fabrication of broadband surface-micromachined micro-electro-mechanical switches for microwave and millimeter-wave applications |
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- 2005-11-17 CN CN200510086892A patent/CN100579893C/en not_active Expired - Fee Related
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6331257B1 (en) * | 1998-05-15 | 2001-12-18 | Hughes Electronics Corporation | Fabrication of broadband surface-micromachined micro-electro-mechanical switches for microwave and millimeter-wave applications |
| CN1211064A (en) * | 1998-07-03 | 1999-03-17 | 北京大学 | Polysilicon structure discharge technology for surface treatment |
Non-Patent Citations (1)
| Title |
|---|
| RF/MW MEMS开关中聚酰亚胺的牺牲层技术研究. 胡梅丽等.微电子学，第35卷第1期. 2005 * |
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Granted publication date: 20100113 Termination date: 20151117 |