CN1139087C

CN1139087C - Shape-changeable and resilience film capacitor having additional electrode plate

Info

Publication number: CN1139087C
Application number: CNB981001858A
Authority: CN
Inventors: 耿胡; 胡耿
Original assignee: Individual
Current assignee: Individual
Priority date: 1998-02-04
Filing date: 1998-02-04
Publication date: 2004-02-18
Anticipated expiration: 2018-02-04
Also published as: CN1225494A

Abstract

The present invention relates to a deformable film capacitor device with an additional capacitor electrode plate, which belongs to the field of micro-electromechanical devices. At least one of two capacitor electrode plates of the device is an additional electrode plate which is attached to the deformable electric film. The area of the additional electrode plate is larger than that of the film and is not deformed following the deformation of the film. The present invention can be made into various small-size and high-sensitivity capacitor type micro-electromechanical devices, such as pressure sensors, microphones, acoustic emission devices, acoustic measurement device, resonators, etc.

Description

The deformable elastic thin-film capacitor device that has additional pole plate

The present invention relates to a kind of deformable elastic thin-film capacitor device that has additional pole plate, belong to the micro electro mechanical device field.

Present existing minisize condenser type elastic film part category is a lot, and its membrane structure is identical with United States Patent (USP) U.S.Patent 4203128 shown in Figure 1 mostly.01 is the silicon chip that has silicon thin film among Fig. 1, the 03rd, and silicon chip, the 02nd, thickness is the sio2 spacer insulator layer of 1 μ.Two silicon chips promptly are two pole plates of capacitor, and spacing only is that 1 μ thereby entire device can be done very for a short time and still have bigger background capacitance.But the problem that a common point is arranged with the condenser type micro electro mechanical device that this membrane structure is made---the electric capacity relative variation is less.Because no matter be, near the marginal portion of film at mechanical external force or under the electric field force effect during film deformational displacement.Its displacement is more little of being zero.This situation has greatly reduced the sensitivity of device.

The objective of the invention is to propose a kind of new small die opening elastic film capacitance structure.Not only external form is little but also highly sensitive for the elastic film condenser type micro electro mechanical device of employing structure of the present invention.

Content of the present invention is to have the deformable elastic thin-film capacitor device of additional pole plate by the elastic film that has the webbing frame, Gu additional capacitor pole plate and another capacitor plate composition in the elastic film centre.Additional pole plate only keeps the area of very little contact area and additional pole plate can be greater than the area of elastic film with the elastic film centre.Another capacitor plate and additional pole plate keep fine pitch, and it can be the flat substrate of conductivity, also can be the substrates that has additional pole plate on another elastic film.

The periphery fixed deformable elastic thin-film capacitor device that has additional pole plate of the present invention, when elastic film under ambient pressure or electric field force effect during the deformation of generator tool, additional pole plate attached to the elastic film centre produces maximum displacement and keeps original shape, compare as the situation of capacitor plate with elastic film itself, the former obviously can produce the variation of much bigger capacitance, thereby thereby greatly improves the sensitivity of device and fall the performance of end device intrinsic various drifts obviously raising device relatively.

Description of drawings:

Fig. 1 is the prior art schematic diagram.

Fig. 2-Figure 11 is 8 embodiment of the present invention.

Figure 12-Figure 15 is the basic manufacture process schematic diagram of the present invention.

Figure 17-Figure 20 is other 4 embodiment of the present invention.

Introduce content of the present invention in detail below in conjunction with accompanying drawing.

Fig. 2 is first embodiment of the present invention.1 is the silicon chip that has silicon thin film among the figure, the 2nd, and the Sio2 insulating barrier, the 3rd, have the silicon chip of pit, the 4th, have the additional capacitor battery lead plate of central pivot point.The central pivot point of pole plate 4 is fixed on the centre of silicon thin film, so when film deformation, the displacement of additional electrical pole plate 4 equates with the maximum displacement in silicon thin film centre, and because the fulcrum cross-sectional area of additional pole plate is very little, so it is constant all the time to be in the thin film center position displacement process its shape again.As long as silicon chip 3 pit depths are suitable, make between supplemantary electrode 4 and the pit bottom to have small die opening as another appearance pole plate, just can make this device that very little volume is only arranged and have big background capacitance and electric capacity relative variation simultaneously.As shown in Figure 2, the area of additional pole plate 4 is greater than the area of silicon thin film, thereby this not only can make the more firm electric capacity relative variation that reduces sluggishness and strengthened device of frame of silicon thin film, but also has reduced Sio ₂The area of insulating barrier has improved long term device stability.

Fig. 3 is second embodiment of the present invention.It is formed in parallel by independent device arrayization shown in Figure 2.The device of making like this has bigger background capacitance so that obtain higher resolution with better simply drive circuit, has also improved consistency of product.

Fig. 4-Fig. 6 is the 3rd embodiment of the present invention.Additional pole plate 5 is that it is that a plurality of independent elastic films are common with the difference of additional pole plate 4 among the figure.The truncation pyramid shape projection that equates with frame of height is arranged in the pit of silicon chip 3, and projection is supported on position between silicon chip 1 film by adding perforate on the pole plate 5.The background capacitance of the device of this structure and electric capacity relative variation further strengthen or do the cross section of device forr a short time on the basis that guarantees certain capacitance.Square opening among Fig. 5 on the visible additional pole plate 5.Square stain among the figure is that the fulcrum of supplemantary electrode 5 also is the contact of it and silicon thin film.Fig. 6 is the sectional view of silicon chip 3.Watch entire device from the A-A section along the direction of arrow, can see sectional view shown in Figure 4.2 is Sio ₂Spacer insulator layer.

Fig. 7 is the 4th embodiment of the present invention.Pyrex 7 have replaced silicon chip 3 among the figure, and the conductive layer 8 on it is another pole plates of electric capacity.6 is spacer insulator layer between two capacitor plates among the figure, the Sio that it can be gone out by silicon chip ₂Layer photoetching forms, and also can be low melting point glass layer.

Fig. 8 is the 5th embodiment of the present invention.This device is made up of two silicon chips 1 that have silicon thin film, additional pole plate 4 is all arranged with its electric capacity relative variation of further raising on the film.Same 6 both can be Sio ₂Layer also can be a low melting point glass layer.

Fig. 9 is the 6th embodiment of the present invention.Extend in the pit of additional pole plate 10 to guarantee bigger background capacitance as the truncation pyramid protuberance of the silicon chip 9 of one of capacitor plate among the figure.The advantage of this embodiment be the elastic film outer surface smooth dried to external world scratch little.2 is Sio among the figure ₂Dielectric spacer layer.

Figure 10 is the 7th embodiment of the present invention.Metal conducting layer 8 among the figure on the Pyrex 7 is one of capacitor plates.The difference of the additional pole plate 10 among additional pole plate 11 and Fig. 9 is pit and extension and silicon chip plane parallel that it stretches out silicon chip 1.This structure can replace having the pole plate 9 of protuberance with flat plate 7, thereby main is that it has further reduced film size and makes frame portion firmer under the situation that does not increase device area, firmer frame has then reduced the requirement of strength to spacer insulator layer 6, even uses bonding substrate 6 of simple organic adhesive and silicon chip 1 also can make the sluggishness of this device very little.The also available certainly flat silicon chip of substrate 7 replaces.

Figure 11 is an eighth embodiment of the invention.The characteristics of present embodiment are that the film both sides of silicon chip 1 all have additional pole plate 4.The opening of insulating barrier 2 and 6 (not drawing among the figure) is communicated to different parts respectively, can be used to measure the pressure differential at this two place, also can make a sealing in two cavitys, thereby become the transducer of measuring absolute pressure.This is a differential capacitance transducer with two sensing capacitances, and sensitivity and linearity are all better.

Figure 12-the 16th illustrates the schematic diagram of the basic manufacturing process of the present invention.This basic manufacturing process is:

1, the preparation silicon chip that has silicon thin film as shown in figure 12.

Concrete steps are:

A, (100) silicon chip of getting common making integrated circuit clean up back one side oxidation and go out the thick Sio of 1 μ ₂Layer, another is towards interior diffused with boron.Protect the concentration of loosing and to reach 10 ¹⁹/ cm ³, the degree of depth is the desired film thickness that obtains.

B, at the Sio that has of this silicon chip ₂The face of layer makes square hole by lithography.Square hole size decision film size.By square hole silicon is carried out the final silicon chip 1 that has silicon thin film that forms of anisotropic etch.The detailed process process can be referring to Volume MAG-11 IEEE Transactions onMagnetics Mar.2,1975 " single Crystal Silicon BarrierJosephson Junction; " P766 also can be referring to J.Electrochem.Soc.:SOLID STATE SIENCE AND TECHNOLOGY August 1978 " TheFabrication of Highprecision nozzles by the AnisotropicEtching of (100) Silicon p1321.

2,, and make the aperture of length of side 3-5 μ by lithography in the position corresponding with the silicon thin film center as shown in figure 13 at the lower surface of silicon thin film coating transition zone 12.Transition zone can be silicon dioxide, silicon nitride, also can be photoresist AZ-1350, and thickness 0.5 μ is to several μ.

3, as shown in figure 14, on transition zone 12, apply one deck conductive layer again, its thickness should surpass transition zone more than 2 times with the intensity that guarantees additional pole plate fulcrum with prevent the obviously deformation under the electric field force effect of additional pole plate.If transition zone is silicon dioxide or silica, then conductive layer adopts polysilicon, if transition zone is the AZ-1350 photoresist, then can adopt aluminium is conductive layer.Conductive layer is photo-etched into additional pole plate and the transition zone etching off or dissolve, additional pole plate just completes, as shown in figure 15.Silicon dioxide layer can be obtained by the silicon chip thermal oxidation, and silicon nitride, polysilicon can obtain with the CVD method, and the three all adopts the conventional semiconductor fabrication process can be referring to " ic manufacturing technology---principle with put into practice " (the author village is same once waited) relevant chapters and sections of a book.

4, the silicon chip 3 of band pit shown in Figure 16 is to produce with the anisotropic etch method equally, and its corrosion depth is controlled by etching time.The Sio that the silicon chip upper surface adheres to ₂ Layer 2 is to be photo-etched into after the silicon chip thermal oxidation, it be the mask of corrosion pit be again spacer insulator layer between the device capacitor pole plate, thickness is about 1 μ.

5, on insulating barrier 2, be coated with a small amount of low-melting glass, last lower silicon slice aligning compressed intensification glass is dissolved, promptly two substrates are sealed to together.

If make the transducer of measuring relative pressure, can on the insulating barrier 2 of frame type, make breach and attention by lithography and on breach, not apply low-melting glass so that be in communication with the outside in the sealing-in back cavity.

Fig. 1-each embodiment shown in Figure 11 makes the basic above-mentioned steps that adopts.Make the recessed additional pole plate 10 in middle part and at 11 o'clock, photoetching transition zone centre bore and additional pole plate should adopt projection exposure, should also be noted that the thickness that guarantees the supplemantary electrode inclined-plane, vacuum available ion film plating or chemical plating or CVD technology apply the conductive layer that forms additional pole plate for this reason.If 6 appropriate to the occasion employing frit seals at interval above several microns.The formation of the truncation pyramid boss among Fig. 9 on the silicon chip 9 is identical with the formation method of pit, as long as mask is become opaque square by transparent square hole.The silicon thin film two sides all has additional pole plate 4 among Figure 11, but its making two sides carry out simultaneously, there is no special character.

Figure 17 is another silicon thin film capacitor element.Two surfaces that are characterized in silicon chip 1 all concave.This had both strengthened the support strength of silicon chip frame portion to film, also was convenient to control the spacing between additional pole plate 4 and another capacitor plate 8.Because support strength is big, silicon chip 1 and the sealing-in of substrate 7 can be used common organic adhesive such as cyano group acrylic acid ester and keep superperformance.Can certainly be sealed to two silicon chips 1 that have additional pole plate 4 as shown in figure 17 and make the high device of sluggish sluggishness together.

The characteristics of thin-film capacitor device shown in Figure 180 are that its film is not Si and hundred Sio ₂, diamond, aluminium oxide elastomeric material be in order to satisfy the demand of specific occasion.Its benefit is that also thickness is convenient to accurate control.Sio ₂Film can be generated by thermal oxidation, and diamond, aluminum oxide film then generate on the Si sheet earlier then from the back side the silicon etching off of corresponding site with the CVD method, its technical process and aforementioned basic identical.

The characteristics of silicon thin film device shown in Figure 19 are the pits that additional pole plate 4 is positioned at silicon thin film, and the outer surface of this device is smooth, scratch for a short time to external world, and distortion is little.

Embodiment illustrated in fig. 20 is the combination of Figure 17 and Figure 10 embodiment, can certainly be sealed to the silicon chip 1 of the additional pole plate 11 of two bands shown in Figure 20 and form the little device of a kind of highly sensitive sluggishness together.

More than all embodiment all can be used as capacitance pressure transducer, and use, sealing can be surveyed absolute pressure as cavity, cavity hatch can be surveyed relative pressure.They also can be used as acoustimeter, words letter, apply the alternating voltage signal as two pole plates to them, can also put and resonating device as acoustic emission is strong.

Claims

1, a kind of deformable elastic thin-film capacitor device that has additional pole plate, comprise substrate and spacer insulator layer, wherein have at least a substrate to have the deformable elastic film of periphery fixed, also comprise at least one additional capacitor pole plate, the central pivot point of each additional capacitor pole plate is fixed on deformable elastic thin film center place, it is characterized in that described additional capacitor pole plate is the film that forms with vacuum evaporation or chemical deposition method, its central pivot point is the part of described additional capacitor pole plate.

By the described deformable elastic thin-film capacitor device that has additional pole plate of claim 1, it is characterized in that 2, described substrate is the silicon chip of band pit, described deformable elastic film is positioned at described pit; Described additional capacitor pole plate is all or part of to be positioned at described pit.

3, by the described deformable elastic thin-film capacitor device that has additional pole plate of claim 1, it is characterized in that described deformable elastic film is the film of silicon dioxide material, aluminium oxide material or diamond material.