CN102897704A - Micro-electro-mechanical comb tooth mechanism capable of adjusting tooth gaps by electrostatic force - Google Patents

Abstract

The invention discloses a micro-electromechanical comb tooth mechanism for modulating tooth gaps by electrostatic force, including electrostatic drive teeth, fixed teeth composed of left-moving fixed teeth and right-moving fixed teeth, movable teeth, a first anchor area and an insulating substrate , the first anchor area is fixedly connected on the insulating substrate; the left-moving fixed teeth include the first wide beam, the left-moving comb teeth, and four first folded beams bent along the transverse direction; the right-moving fixed teeth include the second wide beam, Right-moving comb teeth, four second folded beams bent along the transverse direction; the electrostatic drive teeth include comb teeth and the third anchor area, and the right-moving comb teeth, comb teeth and left-moving comb teeth are arranged alternately in sequence; the movable teeth include mass blocks , movable tooth comb, second anchor area and third folded beam bent longitudinally, and the right-moving comb, movable tooth comb and left-moving comb are arranged alternately in sequence, and the first wide beam is provided with a left-moving stopper block, the second wide beam is provided with a right-moving stop block. Driven by the electrostatic force, the micro-electromechanical comb tooth mechanism adjusts the tooth gap, so that the signal generated by the micro-electromechanical vibration is strong.

Description

A Micro-Electro-Mechanical Comb Mechanism Using Electrostatic Force to Modulate the Teeth Gap

technical field

The invention belongs to the technical field of micro-electro-mechanical system structure, and in particular relates to a micro-electro-mechanical comb mechanism for adjusting the gap between teeth by electrostatic force.

Background technique

Comb structures are widely used in MEMS, for example, resonators, accelerometers, angular velocity meters, gyroscopes, etc. The traditional comb structure consists of paired fixed teeth and movable teeth. The fixed teeth and movable teeth are arranged at intervals and usually have many pairs. In the traditional structure, the fixed teeth remain in a static state without longitudinal and lateral displacement, while the movable teeth usually move in the form of vibration under the action of external force, and the direction of motion is along the length of the teeth.

Due to the limitation of machining accuracy, the gap between the fixed tooth and the movable tooth in the comb tooth structure cannot be smaller than the resolution of the process, and it is also limited by the aspect ratio of dry etching. On the other hand, the movement range of the movable teeth is not only related to the magnitude of the applied external force, but also related to the gap between the fixed teeth and the movable teeth. Since the gap between the teeth of the comb in the traditional structure is invariable and cannot be made very small due to the limitation of the technology, the sensing detection signal generated by the micro-electromechanical vibration is also very weak.

Some researchers have proposed a comb structure with adjustable gaps on one side, but this structure has the following two main disadvantages: because the comb teeth are usually a multi-pair structure, the reduction of the gap on one side will inevitably lead to the increase of the gap on the other side, which is wasteful. The driving force on one side; because the gap on both sides of the movable tooth is asymmetrical, the magnitude of the electrostatic force between the movable tooth and the fixed teeth on both sides is different, and the one-dimensional linear motion of the movable tooth will be affected, resulting in two-dimensional motion.

Contents of the invention

Technical problem: The technical problem to be solved by the present invention is to provide a micro-electromechanical comb tooth mechanism that modulates the gap between the teeth by electrostatic force. The resulting signal is strong.

Technical scheme: in order to achieve the above object, the technical scheme adopted in the present invention is:

A micro-electromechanical comb tooth mechanism that modulates the tooth gap by electrostatic force, the micro-electromechanical comb tooth mechanism includes electrostatic drive teeth, fixed teeth consisting of left-moving fixed teeth and right-moving fixed teeth, movable teeth, and four first anchor areas and an insulating substrate, the four first anchor regions are respectively fixedly connected to the insulating substrate;

The left-moving fixed teeth include a first wide beam, left-moving comb teeth, and four first folded beams bent transversely. The left-moving comb teeth are fixed on both sides of the first wide beam, and the two ends of the first wide beam The two sides are respectively connected to a first anchorage area through a first folding beam; the left-moving fixed teeth are in a suspended state;

The right-moving fixed teeth include a second wide beam, right-moving comb teeth, and four second folded beams bent transversely. The right-moving comb teeth are fixed on both sides of the second wide beam, and the two ends of the second wide beam The two sides are respectively connected to a first anchorage area through a second folded beam; the right-moving fixed teeth are in a suspended state;

The electrostatically driven teeth include comb teeth and a third anchor area, the third anchor area is fixedly connected to the insulating substrate, the comb teeth are fixed on one side of the third anchor area, and the comb teeth move right, comb teeth and left The comb teeth are arranged alternately in sequence; the comb teeth are in a suspended state;

The movable tooth includes a mass block, a movable tooth comb, two second anchor areas and two third folded beams bent longitudinally, the two second anchor areas are fixedly connected to the insulating substrate, and each second The anchor area is connected to one end of a third folded beam, and the other end of the third folded beam is connected to the mass block, and the movable tooth comb is set on one side of the mass block, and the right moving comb, the movable tooth comb and the left moving comb The teeth are alternately arranged in turn, the distance between adjacent right-moving comb teeth and moving tooth comb teeth, the distance between adjacent moving tooth comb teeth and left-moving comb teeth, and the distance between adjacent right-moving comb teeth and comb teeth The distance between the adjacent comb teeth and the left-moving comb teeth is equal; the mass block, the movable tooth comb teeth, and the third folded beam are all in a suspended state;

The first wide beam of the left-moving fixed teeth is provided with a left-moving stop block, and the second wide beam of the right-moving fixed teeth is provided with a right-moving stop block, a left-moving stop block and a right-moving stop block They are arranged oppositely, and the distance between the left-moving stopper and the right-movement stopper is less than twice the design distance between the adjacent right-moving comb teeth and the movable tooth comb teeth.

Beneficial effects: compared with the prior art, the present invention has the following beneficial effects:

Driven by the electrostatic force, the micro-electromechanical comb tooth mechanism adjusts the tooth gap, so that the signal generated by the micro-electromechanical vibration is strong. In the micro-electromechanical comb mechanism of the present invention, on one side of the mechanism, the right-moving combs, movable combs and left-moving combs are arranged alternately in sequence, and on the other side of the mechanism, the right-moving combs, combs and left The comb teeth are arranged alternately in turn. A voltage is applied between the third anchor area and the first anchor area, and at the same time, a voltage is applied between the second anchor area and the first anchor area, so that the right-moving fixed teeth move to the right, and the left-moving fixed teeth move to the left. Moving the fixed teeth to the right and moving the fixed teeth to the left synchronously adjusts the gap between them and the comb teeth of the movable teeth or between the comb teeth, which can increase the sensing detection signal amplitude of the sensor. By changing the magnitude of the applied voltage, the moving distance of the right-moving comb and the left-moving comb can be adjusted. In the design of the micro-electromechanical sensor, the structure of the present invention can be conveniently used to reduce the gap between the teeth and greatly increase the detection sensitivity of the sensor. On the other hand, if the driving signal amplitude of the tooth gap is changed with time, the gap can also be changed with time, so that the vibration amplitude of the movable tooth in the resonant state can be modulated to realize the amplitude modulation of the signal and expand the application of the comb structure scope.

Description of drawings

Figure 1 is a top view of the present invention.

Fig. 2 is a partial structural diagram of the present invention.

Fig. 3 is a sectional view of A-A in Fig. 2 .

Fig. 4 is a B-B sectional view in Fig. 2 .

Fig. 5 is a schematic diagram of the first anchor region on the insulating substrate in the present invention.

Fig. 6 is a top view of the first polysilicon layer during preparation of the present invention.

Fig. 7 is a top view of the composite of the first polysilicon layer and the second polysilicon layer during the preparation of the present invention.

Fig. 8 is a top view of the third polysilicon layer during preparation of the present invention.

In the figure, there are: insulating substrate 100, comb teeth 101, third anchor region 102, left-moving fixed teeth 103, right-moving fixed teeth 104, mass block 105, movable tooth comb teeth 106, first wide beam 107, left-shift comb Teeth 108, second wide beam 109, right-moving comb teeth 110, first folding beam 111, first anchor area 112, second folding beam 113, third folding beam 114, second anchor area 115, left-moving stop block 116 . Move the stop block 117 to the right, the first polysilicon layer 200 , the second polysilicon layer 201 , the third polysilicon layer 202 , and the metal block 203 .

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings.

As shown in Fig. 1 to Fig. 4, a micro-electromechanical comb-tooth mechanism of the present invention for modulating the tooth gap by electrostatic force includes electrostatically driven teeth, a fixed tooth consisting of a left-moving fixed tooth 103 and a right-moving fixed tooth 104, a moving teeth, the four first anchor regions 112 and the insulating substrate 100. The four first anchor regions 112 are respectively fixedly connected to the insulating substrate 100 . The left-moving fixed tooth 103 includes a first wide beam 107 , a left-moving comb tooth 108 , and four first folded beams 111 bent along the transverse direction. When the first folded beam 111 bent along the transverse direction moves, it can only move along the transverse direction. The left-moving comb teeth 108 are fixed on both sides of the first wide beam 107 . Both ends of the first wide beam 107 are respectively connected to a first anchor area 112 through a first folded beam 111 . The left fixed tooth 103 is in a suspended state. The right-moving fixed tooth 104 includes a second wide beam 109 , a right-moving comb tooth 110 , and four second folded beams 113 bent along the transverse direction. The right-moving comb teeth 110 are fixed on both sides of the second wide beam 109 . Both ends of the second wide beam 109 are respectively connected to a first anchor area 112 through a second folded beam 113 . The right-moving fixed tooth 104 is in a suspended state. The electrostatically driven teeth include comb teeth 101 and a third anchor region 102 . The third anchor region 102 is fixedly connected to the insulating substrate 100 . The comb teeth 101 are fixed on one side of the third anchor area 102, and the right-moving comb teeth 110, the comb teeth 101 and the left-moving comb teeth 108 are arranged alternately in sequence. That is to say, the comb teeth 110 to the right, the comb teeth 101 to the left, and the comb teeth 108 to the left are arranged sequentially, that is, the comb teeth 110 to the right, the comb teeth 101, the comb teeth 108 to the left, ..., the comb teeth 110 to the right , comb teeth 101, move comb teeth 108 to the left. The comb teeth 101 are in a suspended state. The movable tooth includes a mass 105 , a movable tooth comb 106 , two second anchor areas 115 and two third folded beams 114 bent longitudinally. The two second anchor regions 115 are fixedly connected to the insulating substrate 100 . Each second anchorage area 115 is connected to one end of a third folded beam 114, and the other end of the third folded beam 114 is connected to the mass block 105, and the movable tooth comb 106 is arranged on one side of the mass block 105, and moves to the right The teeth 110, the movable comb teeth 106 and the left shift comb teeth 108 are arranged alternately in sequence. That is to say, the right-moving comb teeth 110, the moving-tooth comb teeth 106, and the left-moving comb teeth 108 are arranged sequentially, that is, the right-moving comb teeth 110, the moving-tooth comb teeth 106, the left-moving comb teeth 108, ..., right Move the comb teeth 110, move the comb teeth 106, and move the comb teeth 108 to the left. The distance between the adjacent right-moving comb teeth 110 and the moving-tooth comb teeth 106, the distance between the adjacent moving-tooth comb teeth 106 and the left-moving comb teeth 108, the adjacent right-moving comb teeth 110 and the comb teeth 101 The distance between them, and the distance between the adjacent comb teeth 101 and the left-moving comb teeth 108 are equal. The mass block 105, the movable tooth comb 106, and the third folded beam 114 are all in a suspended state. The first wide beam 107 of the fixed tooth 103 left is provided with a left stop block 116, the second wide beam 109 of the fixed tooth 104 moved right is provided with a right stop block 117, the left stop block 116 and the right The moving stopper 117 is arranged oppositely. The distance between the left-moving stop block 116 and the right-moving stop block 117 is less than twice the designed distance between the adjacent right-moving comb teeth 110 and the movable tooth comb teeth 106 . The design distance refers to the distance between the comb teeth in a static state after the process is completed. That is to say, when the left-moving stop block 116 and the right-moving stop block 117 conflict, the distance between the right-moving comb 110 and the movable comb 106, and the distance between the movable comb 106 and the left comb 108 The distance between them can no longer be adjusted. By setting the left-moving stop block 116 and the right-moving stop block 117, contact between the right-moving comb 110 and the movable comb 106, and between the movable comb 106 and the left 108 is avoided.

Further, the left-moving comb teeth 108 are perpendicular to the first wide beam 107, the right-moving fixed teeth 104 are perpendicular to the second wide beam 109, the mass block 105 is perpendicular to the movable comb teeth 106, and the comb teeth 101 are perpendicular to the second wide beam 109. The three anchor regions 102 are perpendicular.

In the above technical solution, one end of the four first folded beams 111 is respectively connected to the first wide beam 107 , and the other ends of the four first folded beams 111 are respectively connected to one first anchoring area 112 . The support for the first wide beam 107 and the left-moving comb teeth 108 is formed by four first folded beams 111 . One ends of the four second folded beams 113 are respectively connected to the second wide beam 109 , and the other ends of the four second folded beams 113 are respectively connected to one first anchoring area 112 . The support for the second wide beam 109 and the right-moving comb teeth 110 is formed by four second folded beams 113 .

The working principle of the micro-electromechanical comb-tooth mechanism of the electrostatic force modulating tooth gap of the above structure is: a voltage is applied between the third anchor area 102 and the first anchor area 112, and at the same time, a voltage is applied between the second anchor area 115 and the first anchor area. A voltage is applied between 112 , and the magnitude of the voltage is the same as that applied between the third anchor region 102 and the first anchor region 112 . The electrostatic force generated by the applied voltage makes the left-moving fixed tooth 103 and the right-moving fixed tooth 104 move toward each other with the comb tooth 101 or the movable tooth comb tooth 106 as the center. Obviously, the greater the magnitude of the applied voltage, the more the distance between the right-moving comb 110 and the movable comb 106 decreases, and the distance between the left-moving comb 108 and the movable comb 106 also decreases. more. In this way, the purpose of adjusting the gap between comb teeth is reached. By setting the distance between the left-moving stop block 116 and the right-moving stop block 117, it is possible to control the movement between the right-moving comb teeth 110 and the movable-tooth comb teeth 106, between the right-moving comb teeth 110 and the comb teeth 101, and between the left-moving comb teeth. 108 and the comb tooth 101, and the minimum gap between the left comb tooth 108 and the movable tooth comb tooth 106.

The structure of the present invention is completed using basic micro-electromechanical processing technology. As shown in Figures 6 to 8, during preparation, the structural materials of the present invention are from bottom to top: insulating substrate 100, first polysilicon layer 200, second polysilicon layer 201, third polysilicon layer 202 and metal Layer 203.

The first wide beam 107 and the first folded beam 111 of the left-moving fixed teeth 103 are made of the second polysilicon layer 201 . The left-moving comb teeth 108 of the left-moving fixed teeth 103 are manufactured along the length direction by laminating the second polysilicon layer 201 and the third polysilicon layer 202 .

The second wide beam 109 and the second folded beam 113 of the right-moving fixed tooth 104 are made of the third polysilicon layer 202 . The right-moving comb teeth 110 of the right-moving fixed teeth 104 are manufactured along the length direction by laminating the second polysilicon layer 201 and the third polysilicon layer 202 .

The left-moving stopper 116 of the left-moving fixed tooth 103 and the right-moving stopper 117 of the right-moving fixed tooth 104 are manufactured by laminating the second polysilicon layer 201 and the third polysilicon layer 202 .

The mass block 105 in the movable tooth, the movable tooth comb 106 and the third folded beam 114 are all formed by laminating the second polysilicon layer 201 and the third polysilicon layer 202 .

As shown in FIG. 5, the first anchor region 112, the second anchor region 115 and the third anchor region 102 are formed by stacking four layers of materials: from bottom to top is the first layer of polysilicon layer 200, which is bonded to the insulating substrate 100 connection; second polysilicon layer 201; third polysilicon layer 202; metal layer 203 for realizing electrical connection.

The fabrication process of this structure is described below with a typical three-layer polysilicon MEMS surface processing technology.

Select an N-type semiconductor silicon wafer, thermally grow a silicon dioxide layer with a thickness of 100 nanometers, and deposit a layer of silicon nitride with a thickness of 500 nanometers through a chemical vapor deposition process to form an insulating substrate. A first layer of polysilicon with a thickness of 300 nanometers is deposited by a chemical vapor deposition process and N-type heavily doped to make the layer of polysilicon a conductor, and a part of the anchor region is formed by etching by a photolithography process. Phospho-silicate glass (PSG) was deposited to a thickness of 2000 nm using a chemical vapor deposition process, and the anchor region was patterned by photolithography. A second layer of polysilicon with a thickness of 2000 nanometers is deposited by chemical vapor deposition process, N-type heavily doped polysilicon is carried out, and a pattern on the second layer of polysilicon is formed by a photolithography process. Phospho-silicate glass (PSG) with a thickness of 1500 nanometers is deposited by chemical vapor deposition process, and patterns such as anchor area and comb superposition area are formed by photolithography process. A third layer of polysilicon with a thickness of 1500 nanometers is deposited by a chemical vapor deposition process, the polysilicon is heavily doped with N type, and a pattern on the third layer of polysilicon is formed by a photolithography process. A metal electrode pattern is formed on the anchor region by a lift-off process. Finally the structure is released by corrosion.

The above is only a preferred embodiment of the present invention, it should be pointed out that for those of ordinary skill in the art, without departing from the principle of the present invention, some improvements and modifications can also be made, and these improvements and modifications are also possible. It should be regarded as the protection scope of the present invention.

Claims (2)

1. the micro electronmechanical broach mechanism of an electrostatic force modulation backlash, it is characterized in that: this micro electronmechanical broach mechanism comprises the static driving gear, decide tooth (103) by moving to left and move to right decide that tooth (104) forms decide tooth, moving tooth, four the first anchor districts (112) and dielectric substrate (100), four the first anchor districts (112) are fixedly connected on respectively on the dielectric substrate (100);

Described moving to left decided the first fold stoplogs (111) that tooth (103) comprises the first wide beam (107), the broach that moves to left (108), four horizontal bendings in edge, the broach (108) that moves to left is fixed on the both sides of the first wide beam (107), and the both sides at the first wide beam (107) two ends are connected in the first anchor district (112) by a first fold stoplog (111) respectively; Move to left and decide tooth (103) and be in vacant state;

Described moving to right decided the second folded beams (113) that tooth (104) comprises the second wide beam (109), the broach that moves to right (110), four horizontal bendings in edge, the broach (110) that moves to right is fixed on the both sides of the second wide beam (109), and the both sides at the second wide beam (109) two ends are connected in the first anchor district (112) by second folded beam (113) respectively; Move to right and decide tooth (104) and be in vacant state;

Described static driving gear comprises broach (101) and the 3rd anchor district (102), the 3rd anchor district (102) is fixedly connected on the dielectric substrate (100), broach (101) is fixed on a side in the 3rd anchor district (102), and the broach that moves to right (110), broach (101) and the broach that moves to left (108) are alternately arranged successively; Broach (101) is in vacant state;

Described moving tooth comprises mass (105), moving stripping fork tooth (106), two the second anchor districts (115) and two are crooked the 3rd folded beam (114) longitudinally, two the second anchor districts (115) are fixedly connected on the dielectric substrate (100), each second anchor district (115) is connected with an end of the 3rd folded beam (114), the other end of the 3rd folded beam (114) is connected with mass (105), moving stripping fork tooth (106) is arranged on a side of mass (105), and the broach that moves to right (110), moving stripping fork tooth (106) and the broach that moves to left (108) are alternately arranged the adjacent broach that moves to right (110) and the distance between the moving stripping fork tooth (106) successively, distance between adjacent moving stripping fork tooth (106) and the broach that moves to left (108), the adjacent broach that moves to right (110) and the distance between the broach (101), and the distance between adjacent broach (101) and the broach that moves to left (108) equates; Mass (105), moving stripping fork tooth (106) and the 3rd folded beam (114) all are in vacant state;

Described the first wide beam (107) of deciding tooth (103) that moves to left is provided with the stop block that moves to left (116), the second wide beam (109) of deciding tooth (104) that moves to right is provided with the stop block that moves to right (117), move to left stop block (116) and the stop block that moves to right (117) is oppositely arranged, and the distance between the stop block that moves to left (116) and the stop block that moves to right (117) is less than the twice of designed distance between the adjacent broach that moves to right (110) and the moving stripping fork tooth (106).

2. according to the micro electronmechanical broach mechanism of electrostatic force modulation claimed in claim 1 backlash, it is characterized in that: the described broach that moves to left (108) is perpendicular with the first wide beam (107), moving to right, it is perpendicular with the second wide beam (109) to decide tooth (104), mass (105) is perpendicular with moving stripping fork tooth (106), and broach (101) is perpendicular with the 3rd anchor district (102).

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