CN101252329B

CN101252329B - Method for manufacturing low-driving-voltage micro-holding type actuator and structure thereof

Info

Publication number: CN101252329B
Application number: CN200710003171XA
Authority: CN
Inventors: 洪银树; 黄义佑; 李彦其; 林君颖
Original assignee: Sunonwealth Electric Machine Industry Co Ltd
Current assignee: Sunonwealth Electric Machine Industry Co Ltd
Priority date: 2007-02-25
Filing date: 2007-02-25
Publication date: 2010-11-03
Anticipated expiration: 2027-02-25
Also published as: CN101252329A

Abstract

The invention relates to a method for manufacturing a low-driving-voltage micro-holding type actuator and a structure thereof, comprising the following steps of: depositing an insulating layer on an ultra-low resistance silicon substrate, and etching the insulating layer after a first lithography process to expose a predetermined position of a lower electrode of the ultra-low resistance silicon substrate; depositing a first low-stress sacrificial layer on the insulating layer, and defining the anchor, the micro bump predetermined position and the bushing pattern by etching in a second photolithography process; depositing a second low stress sacrificial layer on the first low stress sacrificial layer to correct the minimum linewidth of the bushing to be less than 1.5 μm; etching and defining the patterns of the anchor and the preset position of the lower electrode in the third micro-image process; depositing a main structure layer on the second low-stress sacrificial layer, and putting the main structure layer into a horizontal furnace tube to perform phosphorus diffusion and high-temperature annealing processes; defining the pattern of the main structure layer by etching in the fourth micro-image process; defining the pattern of the upper electrode and the lower electrode by the fifth lithography process; the first and second low stress sacrificial layers are wet etched to release the main structure layer.

Description

Make the method and the structure thereof of low driving voltage micro-holding type actuator

Technical field

The present invention relates to a kind of method and structure thereof of making low driving voltage micro-holding type actuator, it applies to the face type micro-processing technology (Surface Micromechaning Technology) of similar manufacture of semiconductor technology, have a batch making, low-cost and integrated characteristic, to solve the traditional IC technical disadvantages.

Background technology

The global in recent years mini-fan (Micro Fan) that is developed is utilization MEMS (micro electro mechanical system) (Microelectromechanical Systems; MEMS) fabrication techniques element, its size approximately has only 2mm * 2mm.The structure of mini-fan comprises two parts, and the first is made the gentle breeze fan blade with self-packaging technology (Self-assembly), and it two is with micro-holding type actuator (Scratch Drive Actuator; SDA) micro motor of forming as rotor (Micro Motor), and the detailed making step of micro motor is multi-user MEMS processing procedure (the Multi-User MEMS Processes that adopts MEMSCAP company to be developed; MUMPs).

Micro-holding type actuator is quite extensive on using, and manner of execution is also a lot, and existing many people delivered the research about micro-holding type actuator on the international periodical, for example:

The micro-holding type actuator notion that people such as Junqi Zhu at first propose, form its primary structure by polysilicon, active principle is to utilize the electrostatic force of vertical direction to make actuating dull and stereotyped (Plate) and axle bush (Bushing) friction bottom surface insulating barrier produce horizontal actuation force, and different micro-holding type actuator arrangement modes can be formed orthoscopic actuator or stepping rotation motor.

People such as Terunobu Akiyama advance distance relation by the velocity of displacement of experimental observation micro-holding type actuator and input voltage frequency relation, input voltage peak value and each walking and activate dull and stereotyped length and distance relation is advanced in each walking, and micro-holding type actuator is connected in a flexible rod member, utilize the power output of the deflection (Buckling) of flexible rod member, and draw the relation of input voltage peak value and power output with the measurement micro-holding type actuator.

People such as P.Langlet are with the driver of micro-holding type actuator as the X/Y precisely locating platform, and with the location of this platform application in the optical fiber coupling, the process experimental result obtains the influence of different actuating flat geometry to the micro-holding type actuator qualification rate.

People such as Mita are fixed in a plurality of micro-holding type actuators of turning one's coat and are formed array on the glass baseplate with special combination technology (Boading), form the micro-holding type actuator conveyer belt.

Yamato Fukuta is to reinvent shape technology (Reshaping technology) with oneself assembling (Self-assembling) device of micro-holding type actuator as three-dimensional structure.

People such as Lin import micro-holding type actuator with guide rail with voltage, and make it promote XYZ three-dimensional platform, mirror surface and little Fresnel (Fresnel) lens, form free space (Free-space) micro-optic laboratory table.

People such as Ryan J.Linderman form 188 micro-holding type actuators array and connect the object that will activate by special combination technology (Boading), import voltage with little chain again.On the other hand the micro-holding type actuator array is fixed on the ceramic wafer with Flip chip bonding (covering crystalline substance) technology, and comes the resulting best dull and stereotyped length that activates of proof theory derivation with experiment.

Paul E.Kladitis with circular arrangement, forms the rotation motor of diameter 520 μ m with micro-holding type actuator, and the silicon blade erected is fixed on this motor, can be applicable to promote microfluid.

Up to the present, all documents all can't accurately measure out the strength that micro-holding type actuator can export and the permissible range of displacement, the life-span that can operate and mode and operating voltage, owing to need to integrate multinomial highly difficult key technology, its reason of inference is the characteristic of micro-holding type actuator is still failed on top of, and its possible cause is:

(1) suitable electrode layer and insulating barrier are not easy to make.

(2) size design does not reach optimization as yet, comprises shape and the hole size of depth-to-width ratio, beam (cantilever beam) ... or the like.

(3) driving voltage descends.

Above-mentioned each reason all is enough to influence the performance of whole micro-holding type actuator, changing any one parameter all is challenge to the integration of whole processing procedure, developing complete processing procedure integration step and carry out theory and experiment optimization, is the bottleneck of difficult breakthrough of present micro-holding type actuator.

As shown in Figure 1, operating principle for micro-holding type actuator, when actuating dull and stereotyped 10 and axle bush 11 have capacitive structure to form, can in actuating dull and stereotyped 10, obtain electrostatic force, in the time of on being added on actuating dull and stereotyped 10 outside the periodic electrostatic force of tool, can cause actuating dull and stereotyped 10 on substrate 12, to form step motion, promptly describe when adding the stepwise operation of square wave between actuating dull and stereotyped 10 and substrate 12 as (b) among the figure, (c), (d).

When adding a positive bias, activating dull and stereotyped 10 is attracted by substrate 12 because of electrostatic force, but activate dull and stereotyped 10 the place aheads and have axle bush 11, its whole flat area can't be adsorbed on the insulating barrier (insulator) 13 fully, therefore have electric charge and be temporary in the actuating dull and stereotyped 10, and then cause actuating dull and stereotyped 10 to have elasticity tension.

When voltage descended, this elasticity tension was released immediately, made that activating dull and stereotyped 10 returns to the original form, and when release voltage, because axle bush 11 contacts with insulating barrier 13 always, can produce frictional force and allow whole actuating dull and stereotyped 10 advance.

When adding a back bias voltage again, activate dull and stereotyped 10 and also can be produced the action that repeats, make to activate dull and stereotyped 10 continuous actions on insulating barrier 13 by substrate 12 absorption.

The action that activates flat board 10 can be controlled by applying pulse, and speed and pulse frequency are directly proportional, Δ x value shown in the figure may be defined to the displacement that applied voltage causes, and this Δ x value is not only relevant with voltage amplitude also relevant with the height of length that activates flat board 10 and axle bush 11.

Summary of the invention

Driving voltage is the key that micro-holding type actuator activates, consider cost, processing procedure is integrated and factor such as processing procedure complexity, main purpose of the present invention is to provide a kind of method and structure thereof of making low driving voltage micro-holding type actuator, can overcome the board limit, and utilize cheaply that fabrication steps reaches high output and low driving voltage purpose.

For achieving the above object, a kind of method of making low driving voltage micro-holding type actuator provided by the present invention, it is characterized in that comprising following steps: step 1: deposition one insulating barrier on a ultralow resistance silicon substrate, and, expose the bottom electrode precalculated position of ultralow resistance silicon substrate at the described insulating barrier of the first road micro-photographing process after etching; Step 2: on described insulating barrier, deposit ground floor low stress sacrifice layer, and define anchor, miniature prominent some precalculated position and axle bush pattern in the second road micro-photographing process etching; Step 3: deposition second layer low stress sacrifice layer on described ground floor low stress sacrifice layer reaches below the 1.5 μ m to revise the axle bush minimum feature; Step 4: the pattern that defines anchor and bottom electrode precalculated position in the 3rd road micro-photographing process etching; Step 5: deposition main structure layer on described second layer low stress sacrifice layer, and insert horizontal boiler tube and carry out phosphorous diffusion and high annealing processing procedure; Step 6: the pattern that defines the main structure layer in the 4th road micro-photographing process etching; Step 7: define top electrode and bottom electrode pattern in the 5th road micro-photographing process etching; Step 8: with first and second low stress sacrifice layer of Wet-type etching to discharge the main structure layer.

In the technical scheme of the invention described above, the resistance of described ultralow resistance silicon substrate is 0.001～0.004 Ω-cm.

In the technical scheme of the invention described above, described insulating barrier is the low stress nitride silicon thin film.

In the technical scheme of the invention described above, described first and second layer low stress sacrifice layer is the phosphorosilicate glass film.

In the technical scheme of the invention described above, described main structure layer is the low stress polysilicon membrane.

In the technical scheme of the invention described above, described upper and lower electrode is with electron beam evaporation plating machine evaporation chromium/gold.

This method can apply to the structure assembling of the structure assembling of mini-fan motor, little radiating module, structure assembling, micro sprue system and the low-light communication switch of little element of exerting oneself.

The invention provides a kind of structure of low driving voltage micro-holding type actuator, it is characterized in that comprising: a ultralow resistance silicon substrate; One insulating barrier is deposited on the ultralow resistance silicon substrate; At least one main structure layer is deposited on the insulating barrier; Main structure layer below is manufactured with more than one miniature prominent point, to prevent viscid effect.

This structure can apply to the structure assembling of the structure assembling of mini-fan motor, little radiating module, structure assembling, micro sprue system and the low-light communication switch of little element of exerting oneself.

Because traditional micro-holding type actuator is with general resistance silicon substrate (20 Ω-cm) as bottom electrode, driving voltage is greatly about the scope of 70～120V, except the silicon substrate material of bottom electrode can influence driving voltage, the thickness of the height of axle bush, width and main structure layer polysilicon also can influence.Therefore, the present invention utilizes ultralow resistance silicon substrate (0.001～0.004 Ω-cm) as lower electrode material, and change the process parameter of micro-holding type actuator and the minimum feature of adjustment element, and then micro-holding type actuator element drives voltage significantly is reduced between 5～25V.So The present invention be directed to the integrated design research and development of micro motor, significantly reduce the driving voltage of micro-holding type actuator with ultralow resistance silicon substrate, and complete and stable fabrication steps and method is provided, can take into account the integrated possibility that changes into one chip of mini-fan chip and control circuit.

Description of drawings

Fig. 1 is the step motion schematic diagram that micro-holding type actuator adds driving voltage;

Fig. 2 is the tomograph that the present invention makes the micro-holding type brake;

Fig. 3 is a fabrication steps schematic diagram of the present invention;

Fig. 4 is the measurement curve of voltage and deflection voltage at the bottom of the subsides of micro-holding type actuator of the present invention;

Fig. 5 be at the bottom of the subsides of micro-holding type actuator of the present invention voltage with activate the writing board shape graph of a relation;

Fig. 6 is ultralow resistance chip and voltage comparison diagram at the bottom of the subsides of general chip.

Embodiment

The present invention relates to a kind of method and structure thereof of making low driving voltage micro-holding type actuator, with complete and stable fabrication steps and the method for ultralow resistance silicon substrate material fit, can reduce the driving voltage of micro-holding type actuator, and control axle bush width is no more than 1.5 μ m, below is that conjunction with figs. describes innovation processing procedure of the present invention in detail:

As shown in Figure 2, the present invention includes ultralow resistance silicon substrate 20, insulating barrier 21, main structure layer 30 and upper and

lower electrode

41,42 at least.

In order to prevent that viscid effect (sticing effect) from producing, the present invention makes miniature prominent point (Dimple) 31 especially below main structure layer 30 viscid to prevent, detailed making flow process as shown in Figure 3:

(a) on a ultralow resistance silicon substrate 20, deposit low stress nitride silicon thin film (Si3N4) as insulating barrier 21 with Low Pressure Chemical Vapor Deposition (LPCVD), and after the first road micro-photographing process, with inductance coupling high formula electric paste etching machine (ICP) etching isolation layer 21, to expose the bottom electrode precalculated position 25 of ultralow resistance silicon substrate 20.

(b) with plasma enhanced chemical vapor deposition method (PECVD) on insulating barrier 20 sedimentary phosphor silex glass film (PSG-0) as ground floor low stress sacrifice layer 22, and, on ground floor low stress sacrifice layer 22, define anchor (anchor), miniature prominent point (dimple) precalculated position 23 and three patterns of axle bush (bushing) simultaneously with inductance coupling high formula electric paste etching machine (ICP) etching with the second road micro-photographing process.

(c) with plasma enhanced chemical vapor deposition method (PECVD) on ground floor low stress sacrifice layer 22 sedimentary phosphor silex glass film (PSG-1) as second layer low stress sacrifice layer 24, the main purpose of deposition second layer low stress sacrifice layer 24 is to revise the axle bush width, because the live width minimum resolution of exposure bench is 2 μ m, it is 1.5 μ m that but co-operating member must have minimum feature, therefore utilizes this one step to dwindle the minimum feature limit that board has no idea to reach.

(d) the 3rd road micro-photographing process defines the pattern in anchor and bottom electrode precalculated position 25 with inductance coupling high formula electric paste etching machine (ICP) etching.

(e) on second layer low stress sacrifice layer 24, deposit low stress polysilicon membrane (Poly-Si) as main structure layer 30 with Low Pressure Chemical Vapor Deposition (LPCVD), and chip is inserted horizontal boiler tube carry out phosphorous diffusion and high annealing processing procedure.

(f) the 4th road micro-photographing process defines the pattern of main structure layer 30 with inductance coupling high formula electric paste etching machine (ICP) etching.

(g), define the pattern of top electrode 41 and bottom electrode 42 with wet etching with electron beam evaporation plating machine evaporation chromium/gold, and at the 5th road micro-photographing process.

(h) element is placed buffered hydrofluoric acid (BOE) carry out Wet-type etching, and first and second low

stress sacrifice layer

22,24 of etching, to discharge main structure layer 30.

As with sweep electron microscope (Scanning Electron Microscope; SEM) take the micro-holding type actuator component structure, just the element suspension structure after discharging as can be seen, because use the low stress polysilicon membrane as the main structure layer, make the planarization of element quite good, can not produce because membrane stress does not match and causes the situation of component failure.

As shown in Figure 4, micro-holding type actuator element of the present invention is after dynamic characteristic test, find that it pastes end voltage (snap voltage) and presents linear relationship with deflection voltage (priming voltage), and conform to predicting the outcome of external simulation, identical with world institute of well-known R﹠D team Simulation result approximate trend, but the driving voltage of micro-holding type actuator element of the present invention is obviously than existing micro-holding type actuator element is much lower in the world.

Again as shown in Figure 5, if inquire at the designed multiple different relations that activate writing board shape and driving voltage of the present invention, test result is found:

When the actuating flat board is triangle (Triangle), its driving voltage is approximately than the high 1～2V of driving voltage of rectangular flat, but triangle flat plate has the significant advantage that more can not shorten the life-span because of stored charge, and triangle flat plate also has short driving time of delay simultaneously.On the other hand, the tail end of rectangular flat not only can reduce stored charge if can add suitable etch-hole design, also can reduce driving voltage simultaneously.

For another shown in Figure 6, if voltage at the bottom of the subsides of more ultralow resistance chip and general chip can clearly be found:

Reducing driving voltage can do correction from bottom electrode (substrate) material of element, and when the present invention integrated at processing procedure, the substrate that utilizes two batches of different resistances was found through after the identical fabrication steps as bottom electrode:

Low-resistance substrate can obtain reducing than common substrate the driving voltage of about 5～6V, and this result and inventor's prediction meets fully.In the future if cooperate the adjustment of top electrode metal material again, expectation can reduce about 10V driving voltage and make it reach voltage quasi position below 10 volts, this helps following micro-holding type actuator with extremely and applies to all kinds of mass production products, for example: the structure assembling of the structure assembling of mini-fan motor, little radiating module, structure assembling, micro sprue system and the low-light communication switch of little assembly of exerting oneself.

In sum, the present invention has possessed above every advantage really, also has the obvious effect enhancement than commonly using structure.

The above only is a preferable enforcement kenel of the present invention, and the equivalent structure that all application specification of the present invention, claims or accompanying drawing are done changes, and all should be included in the scope of patent protection of the present invention.

Claims

1. A method for making a low driving voltage micro-snatch type actuator, characterized in that it comprises the following steps:

Step 1: Deposit an insulating layer on an ultra-low resistance silicon substrate, and etch the insulating layer after the first lithography process, exposing the predetermined position of the lower electrode of the ultra-low resistance silicon substrate; the ultra-low Resistance The resistance of the silicon substrate is 0.001-0.004Ω-cm;

Step 2: Depositing a first low-stress sacrificial layer on the insulating layer, and etching to define anchors, predetermined positions of micro bumps and bushing patterns after the second lithography process;

Step 3: Depositing a second low-stress sacrificial layer on the first low-stress sacrificial layer, so as to correct the minimum line width of the bushing to be less than 1.5 μm;

Step 4: After the third lithography process, etch the pattern defining the predetermined position of the anchor and the lower electrode;

Step 5: Depositing the main structure layer on the second low-stress sacrificial layer, and placing it in a horizontal furnace tube for phosphorus diffusion and high-temperature annealing processes;

Step 6: After the fourth lithography process, etch to define the pattern of the main structure layer;

Step 7: After the fifth lithography process, etch to define the upper electrode and lower electrode patterns;

Step 8: Wet etching the first layer and the second low-stress sacrificial layer to release the main structure layer.

2. The method for manufacturing a low driving voltage micro-snatch actuator according to claim 1, wherein the insulating layer is a low-stress silicon nitride film.

3. The method for manufacturing a low driving voltage micro-snatch actuator according to claim 1, wherein the first and second low-stress sacrificial layers are phosphosilicate glass films.

4. The method for manufacturing a low driving voltage micro-snatch actuator according to claim 1, wherein the main structure layer is a low-stress polysilicon film.

5 . The method for manufacturing a low driving voltage micro-snatch actuator according to claim 1 , wherein the upper and lower electrodes are electrodes formed by evaporating chromium/gold with an electron beam evaporator. 5 .

6. The method for manufacturing a low driving voltage micro-snatch type actuator as claimed in claim 1, characterized in that: the method can be applied to the structural assembly of a micro-fan motor.

7. The method for manufacturing a low driving voltage micro-snatch type actuator according to claim 1, characterized in that: the method can be applied to the structural assembly of a micro-radiation module.

8. The method for manufacturing a low driving voltage micro-snatch actuator according to claim 1, characterized in that: the method can be applied to the structural assembly of micro-output components.

9. The method for manufacturing a low driving voltage micro-snatch actuator according to claim 1, characterized in that: the method can be applied to the structural assembly of a microfluidic system.

10. The method for manufacturing a low driving voltage micro-snatch type actuator according to claim 1, characterized in that: the method can be applied to the structural assembly of micro-optical communication switches.

11. A structure of a low driving voltage micro-snatch type actuator, characterized in that it comprises:

An ultra-low resistance silicon substrate, the resistance of the ultra-low resistance silicon substrate is 0.001-0.004Ω-cm;

an insulating layer deposited on the ultra-low resistance silicon substrate;

at least one primary structural layer deposited on the insulating layer;

One or more micro bumps are fabricated below the main structural layer to prevent sticking effects.

12. The structure of the low driving voltage micro-snatch actuator according to claim 11, wherein the insulating layer is a low-stress silicon nitride film.

13. The structure of the micro-snatch type actuator with low driving voltage according to claim 11, wherein the main structure layer is a low-stress polysilicon film.

14. The structure of the low driving voltage micro-snatch type actuator as claimed in claim 11, characterized in that: the structure can be applied to a micro-fan motor.

15. The structure of the low driving voltage micro-snatch type actuator according to claim 11, characterized in that: the structure can be applied to a micro-radiation module.

16. The structure of the low driving voltage micro-snatch type actuator according to claim 11, characterized in that: the structure can be applied to micro-output elements.

17. The structure of the low driving voltage micro-snatch type actuator according to claim 11, characterized in that: the structure can be applied to a micro-channel system.

18. The structure of the low driving voltage micro-snatch type actuator according to claim 11, characterized in that: the structure can be applied to a low-light communication switch.