CN1816222A - Silicon micro capacitor microphone chip and producing method - Google Patents
Silicon micro capacitor microphone chip and producing method Download PDFInfo
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- CN1816222A CN1816222A CN 200510005385 CN200510005385A CN1816222A CN 1816222 A CN1816222 A CN 1816222A CN 200510005385 CN200510005385 CN 200510005385 CN 200510005385 A CN200510005385 A CN 200510005385A CN 1816222 A CN1816222 A CN 1816222A
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- vibrating membrane
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Abstract
The microphone chip includes silicone substrate, and parts on the substrate including backboard with through holes, isolation layer, vibrating membrane, and electrode. The isolation layer is located between the backboard and vibrating membrane in order to form air gap without sharp-angled borderline. The vibrating membrane possesses a convex ring. The preparation method includes following steps: forming a isolation layer on upper surface of the silicone substrate; a hollow area is limited by a surrounding isolation layer; a sacrificial layer easy to be etched than the isolation layer is formed on upper surface of the silicone substrate, and at least part of the sacrificial layer is field on the said hollow area; carrying out stereo etching for the substrate from lower surface of silicone chip to remove the sacrificial layer so as to form air gap in the place, where there was the sacrificial layer. Thus, designing shape can control shape of the air gap.
Description
Technical field
The present invention relates to the micro electro mechanical device field, specifically, the present invention relates to a kind of silicon micro capacitor microphone chip and preparation method thereof.
Background technology
Silicon micro capacitor microphone is a kind of novel microphone, and it is grouped into by the silicon part and the peripheral circuit portion that form silicon micro capacitor usually.Wherein the silicon micro capacitor chip partly is the core of microphone, and it is to utilize integrated circuit technology to be made on silicon chip.Silicon micro capacitor chip part by silicon chip and on the perforation backboard acoustic holes backboard, air-gap, separator, vibrating membrane and electrode are formed in other words, can be referring to Micro Electro MechanicalSystems (MEMS), 1998 IEEE 11th International Workshop p580-585, by P.-C.Hsu, " the A HIGH SENSITIVITY POLYSILICONDIAPHRAGM CONDENSER MICROPHONE " that C.H.Mastrangelo, and K.D.Wise are shown.
Fig. 1 shows the profile of common silicon micro capacitor microphone chip 10, includes a silicon chip 11.This silicon chip 11 has a hollow part 12, and the upper end of hollow part 12 has a perforation backboard 13 that is formed in the silicon chip upper surface, has the acoustic holes 14 of a plurality of one-tenth array distribution on this perforation backboard 13.Also be formed with a separator 15 at silicon chip 11 upper surfaces, and be formed with a vibrating membrane 16 on the separator 15.By separator 15, between perforation backboard 13 and vibrating membrane 16, provide an air-gap 17.Be respectively arranged with electrode 18 and 18 ' on perforation backboard 13 and the vibrating membrane 16.
Common silicon micro capacitor microphone chip is owing to be subjected to material behavior and preparation method's restriction, and the air-gap 17 in the microphone chip shown in Figure 1 is generally square boundary.Fig. 2 is a profile in the process of the microphone chip 10 of preparation Fig. 1, as shown in Figure 2, on silicon chip 11, form a doped layer 13 ' by doping, this doped layer 13 ' will be configured as perforation backboard 13 in subsequent preparation process, go up at doped layer 13 ' then and form a sacrifice layer 15 ', and go up formation vibrating membrane 16 at sacrifice layer 15 '.Lower surface from silicon chip 11 begins to carry out the body etching then, erode away the hollow part 12 shown in Fig. 1 earlier, continue then upwards unadulterated silicon materials in the doped layer 13 ' to be eroded, form the acoustic holes 14 among Fig. 1, continue upwards corrosion then and erode the air-gap 17 that forms Fig. 1 until a part of sacrifice layer 15 ' that will be arranged between doped layer 13 ' and the vibrating membrane 16, residual a part of sacrifice layer 15 ' then forms the separator 15 among Fig. 1.It should be noted that the border of these hollow part 12 cross sections is a square because the characteristic of silicon chip 11 anisotropic etchs own begins the hollow part 12 (Fig. 1) that the body etching can only produce terrace with edge shape from silicon chip 11 lower surfaces.Like this, when the body etching upwards corrode to the time during sacrifice layer 15 ' because the qualification of corrosion position, the border of the air-gap 17 of formation also be square usually.As shown in Figure 3 from Fig. 1 along shown in the profile of I-I intercepting, the closed border 17 ' of the air-gap 17 that is limited by separator 15 is generally square.
Because air-gap 17 has square boundary, at the sharp corner (for example four of air-gap shown in Fig. 3 17 corners) on its border, the stress that vibrating membrane 16 bears is bigger, produces stress and concentrates, and then cause the sensitivity of microphone to descend, sometimes even can cause breaking of vibrating membrane 16.As seen, in the prior art, the shape of air-gap 17 particularly its boundary shape is uncontrollable basically, is subjected to material behavior and preparation method's restriction, makes the border of air-gap 17 have wedge angle usually, concentrates thereby produce stress.
Summary of the invention
The object of the present invention is to provide a kind of silicon micro capacitor microphone chip, this microphone chip can be avoided producing stress and concentrate; Another object of the present invention is to provide a kind of preparation method of silicon micro capacitor microphone chip, can control the boundary shape of air-gap in the method.
To achieve these goals, the invention provides a kind of silicon micro capacitor microphone chip, comprise silicon chip and on perforation backboard, separator, vibrating membrane and electrode, described separator is between described perforation backboard and described vibrating membrane, so that form air-gap between described perforation backboard and described vibrating membrane; Described air-gap has the border of no wedge angle, and described vibrating membrane has a bulge loop.
Preferably, described air-gap has the smooth boundary.Described air-gap preferably has circular boundary.
The present invention also provides a kind of preparation method of silicon micro capacitor microphone chip, comprising:
One silicon chip with upper surface and lower surface is provided;
From the upper surface of described silicon chip silicon chip is mixed, form a doped layer;
Form a separator on the upper surface of described silicon chip, this separator is around defining a hollow area;
The sacrifice layer that formation one is easier to be etched than described separator on the upper surface of described silicon chip, at least a portion sacrifice layer is filled in the described hollow area;
On described sacrifice layer, form a vibrating membrane;
Begin described silicon chip is carried out the body etching from the lower surface of described silicon chip, and etching is removed described sacrifice layer; Finally, described doped layer forms the perforation backboard of silicon micro capacitor microphone chip, and the position at the sacrifice layer place of the removal that is etched forms the air-gap of silicon micro capacitor microphone chip;
On described vibrating membrane and perforation backboard, electrode is set respectively.
Described sacrifice layer transversely has smooth border at it.Described sacrifice layer transversely has circular boundary at it.Described sacrifice layer has projection longitudinally on its border, so that the vibrating membrane that forms on described sacrifice layer has a bulge loop.Described separator is an earth silicon material, and described sacrifice layer is zinc oxide or phosphorosilicate glass material.
In the present invention, the air-gap shape of silicon micro capacitor microphone chip is limited by corrosion-prone sacrifice layer shape, and the technical staff can obtain needed air-gap shape by the shape of design sacrifice layer, thereby makes that the shape of air-gap is controlled.Particularly, by the present invention, can be so that the border of air-gap have wedge angle, thus avoid the stress of vibrating membrane to concentrate.In addition, the bulge loop structure on the silicon micro capacitor microphone chip vibrating membrane of the present invention can improve the Oscillation Amplitude limit of vibrating membrane, reduces the possibility that vibrating membrane breaks when vibration.
Description of drawings
Fig. 1 is a kind of profile of silicon micro capacitor microphone chip of routine;
Fig. 2 is the profile in the silicon micro capacitor microphone chip process of preparation Fig. 1;
Fig. 3 is the profile along the I-I line drawing of Fig. 1;
Fig. 4～Fig. 7 is a silicon micro capacitor microphone chip preparation method's of the present invention preparation flow, wherein the microphone chip for preparing for the method according to this invention of Fig. 7;
Fig. 8 is the vertical view of silicon micro capacitor microphone chip shown in Figure 7;
Fig. 9 is along the profile of II-II line drawing in Fig. 7;
Figure 10 is the schematic diagram of the boundary shape of sacrifice layer among the silicon micro capacitor microphone chip preparation method of the present invention.
Embodiment
Below in conjunction with the drawings and specific embodiments the present invention is described in further detail.
Fig. 4～Fig. 7 shows the preparation flow of silicon micro capacitor microphone chip of the present invention in one embodiment, wherein the microphone chip for preparing for the method according to this invention of Fig. 7.
As shown in Figure 4, at first choose a silicon chip 100, this silicon chip 100 is＜100〉n
-The type silicon chip.Silicon chip 100 has a upper surface 101 and a lower surface 102, and in one embodiment, the thickness of this silicon chip 100 is 400 microns, but is appreciated that those skilled in the art can select the silicon chip 100 of different-thickness as required.Silicon chip 100 is through high temperature oxidation process growth one deck high temperature silica, and exemplarily, the thickness of this high temperature silica is 1.5 microns; On the upper surface 101 of silicon chip 100,, utilize hydrofluoric acid corrosion high temperature silica to make mask 103 to this floor height temperature silicon dioxide photoetching.Downwards silicon chip 100 is mixed from upper surface 101 beginning then, mask 103 unlapped zones will be doped and form doped layer 104 like this.In this embodiment, what silicon chip 100 was carried out is selective doping, does not promptly mix for the position 106 ' of the acoustic holes that will form silicon micro capacitor microphone chip in subsequent step.In the present embodiment, the doping of silicon chip 100 is to carrying out boron diffusion from 101 pairs of silicon chips of upper surface 100, and diffusion depth can be selected between 1 micron to 20 microns, and those skilled in the art also can make other selection according to actual needs.
As shown in Figure 5, with the high temperature silica mask 103 among hydrofluoric acid removal Fig. 4, the upper surface 101 at silicon chip 100 forms a separator 105 then.In Fig. 8, see clearlyer, this separator 105 is preferably annular, can form by the following method: the upper surface 101 at silicon chip 100 forms one deck low temperature silicon dioxide, then this layer low temperature silicon dioxide is carried out eroding away with hydrofluoric acid after the photoetching separator 105 of annular.Like this, be that the border defines a hollow area 107 ' with separator 105.
Then, as shown in Figure 5, locate to form a sacrifice layer 107 in the hollow area 107 ' that separator 105 is centered on, at least a portion is filled in this hollow area 107 ' and locates in the sacrifice layer 107.In the embodiment of Fig. 5, sacrifice layer 107 has not only been filled hollow area 107 ', and has also covered part separator 105 in its edge.In one embodiment, when separator was low temperature silicon dioxide, 107 of sacrifice layers can be selected zinc oxide or phosphorosilicate glass for use, will know from following description, when corroding, the speed that the speed that zinc oxide or phosphorosilicate glass are corroded will be corroded much larger than low temperature silicon dioxide.In forming the process of sacrifice layer 107, when adopting the phosphorosilicate glass material, available LPCVD or pecvd process are deposited on the upper surface 101 of silicon chip 100 with phosphorosilicate glass, with buffered hydrofluoric acid its corrosion are the circle concentric with separator 105 then; When adopting zinc oxide material, available magnetron sputtering technique is deposited on the upper surface 101 of silicon chip 100 with zinc oxide, with phosphoric acid its corrosion is the circle concentric with separator 105 then.
Then, as shown in Figure 5, utilize upper surface 101 and the lower surface 102 two-sided respectively deposit one deck silicon nitrides of low-pressure chemical vapor phase deposition equipment (LPCVD) at silicon chip 100, exemplarily, the thickness of this silicon nitride layer is 0.5 micron.After upper surface 101 photoetching of silicon chip 100, the silicon nitride layer of upper surface 101 is etched into Round Membranes 108 by plasma etching machine (ICP); After lower surface 102 photoetching of silicon chip 100, the silicon nitride layer of lower surface 102 is etched into mask 109 by plasma etching machine (ICP), and the uncovered area of mask 109 is a square, so that begin silicon chip 100 is carried out the body etching from this square area.
In addition, as shown in Figure 5, sacrifice layer 107 preferably has a projection 112 ' near its edge, and like this, when when forming vibrating membrane 108, vibrating membrane 108 will have projection a 112 ' corresponding bulge loop structure 112 with sacrifice layer 107.
In conjunction with Fig. 5 and Fig. 6, begin silicon chip 100 usefulness potassium hydroxide are carried out silicon body etching from the lower surface 102 of silicon chip 100.In the corrosion process that potassium hydroxide makes progress, at first erode away a hollow part 113, because the characteristic of silicon chip 100 anisotropic etchs own, be similar to the hollow part 12 among Fig. 1, this hollow part 113 also is generally terrace with edge shape, and its horizontal (direction on the upper surface 101 of silicon chip 100 and/or plane, lower surface 102 place) cross section is a square.Then, potassium hydroxide continues upwards corrosion, since potassium hydroxide to the corrosion rate of not carrying out the boron diffusion doped region far above carrying out the boron diffusion doped regions, therefore, the silicon materials that are in acoustic holes position 106 ' (Fig. 4) in the doped layer 104 are by very fast erosion removal, with the acoustic holes 106 of formation silicon micro capacitor microphone chip, thereby make doped layer 104 form the perforation backboards.
Then, buffered hydrofluoric acid is arrived the sacrifice layer 107 that separator 105 is surrounded by acoustic holes 106.As previously mentioned, sacrifice layer 107 has adopted than the separator 105 easier materials that are corroded, for example zinc oxide or phosphorosilicate glass, and therefore, sacrifice layer 107 has been corroded soon, and stays the air-gap 110 identical with sacrifice layer 107 shapes.Therefore as can be known, the shape of air-gap 110 will be limited by the shape of formed sacrifice layer 107 before.Like this, those skilled in the art then can obtain the shape of desirable air-gap 110 by the shape that preestablishes sacrifice layer 107.
At last, as shown in Figure 7, a metal electrode 111 is set respectively, finishes the preparation of silicon micro capacitor microphone chip on the surface of vibrating membrane 108 and doped layer 104.See clearlyer in the vertical view that is arranged on Fig. 8 of electrode 111, these two metal electrodes 111 can be by the upper surface 101 evaporation layer of metal films at silicon chip 100, and for example the aluminium film becomes electrode 111 to this metallic film photoetching and with phosphoric acid corrosion then.
As shown in Figure 7, silicon micro capacitor microphone chip of the present invention comprises silicon chip 100.On the upper surface 101 of silicon chip 100, the doped layer 104 that has by a plurality of acoustic holes 106 forms the perforation backboard, doped layer 104 is provided with separator 105, be provided with vibrating membrane 108 on the separator 105, the surface of vibrating membrane 108 and doped layer 104 is respectively equipped with electrode 111, and between vibrating membrane 108 and doped layer 104, having air-gap 110, this air-gap 110 forms after being corroded by sacrifice layer 107.
Particularly in Fig. 7, as previously mentioned, the shape of this air-gap 110 is limited by the shape of sacrifice layer 107.In one embodiment, the horizontal boundary of sacrifice layer 107 is circular, so the border 110 ' of air-gap 110 also be circular, shown in the profile that intercepts along II-II from Fig. 7 as shown in Figure 9.In fact, those skilled in the art will readily appreciate that, can be by difform sacrifice layer 107 being set, preparing silicon micro capacitor microphone with different air-gap 110 shapes.In other embodiments, the sacrifice layer 107 that no wedge angle border can be set makes the border of air-gap 110 of silicon micro capacitor microphone also not have wedge angle, thereby avoid the stress of vibrating membrane 108 to concentrate, for example, sacrifice layer 107 can have smooth border (all can lead being called on the border each point on the mathematics), makes air-gap 110 also have the border that is essentially smooth curve.Figure 10 shows the smooth boundary shape of several sacrifice layers 107, and correspondingly, the air-gap 110 of the silicon micro capacitor microphone for preparing also has essentially identical border.
Claims (8)
1, a kind of silicon micro capacitor microphone chip, comprise silicon chip and on perforation backboard, separator, vibrating membrane and electrode, described separator is between described perforation backboard and described vibrating membrane, so that form air-gap between described perforation backboard and described vibrating membrane; It is characterized in that described air-gap has the border of no wedge angle, and described vibrating membrane has a bulge loop.
2, silicon micro capacitor microphone chip according to claim 1 is characterized in that, described air-gap has the smooth boundary.
3, silicon micro capacitor microphone chip according to claim 2 is characterized in that, described air-gap has circular boundary.
4, a kind of preparation method of silicon micro capacitor microphone chip comprises:
One silicon chip with upper surface and lower surface is provided;
From the upper surface of described silicon chip silicon chip is mixed, form a doped layer;
Form a separator on the upper surface of described silicon chip, this separator is around defining a hollow area;
The sacrifice layer that formation one is easier to be etched than described separator on the upper surface of described silicon chip, at least a portion sacrifice layer is filled in the described hollow area;
On described sacrifice layer, form a vibrating membrane;
Begin described silicon chip is carried out the body etching from the lower surface of described silicon chip, and etching is removed described sacrifice layer; Finally, described doped layer forms the perforation backboard of silicon micro capacitor microphone chip, and the position at the sacrifice layer place of the removal that is etched forms the air-gap of silicon micro capacitor microphone chip;
On described vibrating membrane and perforation backboard, electrode is set respectively.
5, the preparation method of silicon micro capacitor microphone chip according to claim 4 is characterized in that, described sacrifice layer transversely has smooth border at it.
6, the preparation method of silicon micro capacitor microphone chip according to claim 5 is characterized in that, described sacrifice layer transversely has circular boundary at it.
7, the preparation method of silicon micro capacitor microphone chip according to claim 5 is characterized in that, described sacrifice layer has projection longitudinally on its border, so that the vibrating membrane that forms on described sacrifice layer has a bulge loop.
8, the preparation method of silicon micro capacitor microphone chip according to claim 4 is characterized in that, described separator is an earth silicon material, and described sacrifice layer is zinc oxide or phosphorosilicate glass material.
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| CN 200510005385 CN1816222A (en) | 2005-02-05 | 2005-02-05 | Silicon micro capacitor microphone chip and producing method |
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| CN 200510005385 CN1816222A (en) | 2005-02-05 | 2005-02-05 | Silicon micro capacitor microphone chip and producing method |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106082103A (en) * | 2015-04-29 | 2016-11-09 | 台湾积体电路制造股份有限公司 | Prevent MEMS (MEMS) structure of viscous after wet cleaning |
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2005
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106082103A (en) * | 2015-04-29 | 2016-11-09 | 台湾积体电路制造股份有限公司 | Prevent MEMS (MEMS) structure of viscous after wet cleaning |
| CN106082103B (en) * | 2015-04-29 | 2018-05-11 | 台湾积体电路制造股份有限公司 | Prevent the viscous MEMS after wet cleaning（MEMS）Structure |
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Open date: 20060809 |