CN204330809U - A kind of piezoresistance type acceleration sensor - Google Patents
A kind of piezoresistance type acceleration sensor Download PDFInfo
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- CN204330809U CN204330809U CN201420837962.8U CN201420837962U CN204330809U CN 204330809 U CN204330809 U CN 204330809U CN 201420837962 U CN201420837962 U CN 201420837962U CN 204330809 U CN204330809 U CN 204330809U
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Abstract
The utility model provides a kind of piezoresistance type acceleration sensor, and the improvement of this sensor is sensitive structure part, and the mass left and right sides in sensitive structure is arranged with separate each four sensitive beam, each sensitive beam is established a force sensing resistance; The both sides of four sensitive beam respectively establish one for supporting the brace summer of mass, force sensing resistance are produced on the width that independently sensitive beam can reduce sensitive beam, thus significantly reduce sensitive beam to the impact of the structure coefficient of stiffiness, obtain high sensitivity and the high figure of merit; Sensitive beam is near mass midline position, and its flexure is less, can reduce paraxonic sensitivity.Brace summer is near mass edge, and its arm of force is long, and the mass that paraxonic acceleration can be suppressed better to cause reverses.Brace summer upper surface is lower, and surperficial non-oxidation layer, can reduce the structural deflection that oxide layer stress causes.Sensitive beam thickness is greater than brace summer, can realize stress and concentrate, thus improve sensitivity and the figure of merit.
Description
Technical field
The utility model relates to a kind of piezoresistance type acceleration sensor, particularly relates to a kind of brace summer of different-thickness and sensitive beam of utilizing to improve the piezoresistance type acceleration sensor of sensor performance.
Background technology
Micro-mechanical accelerometer is micro electronmechanical integrated system (Micro Electro Mechanical Systems, MEMS) one of the pillar product of technical field, have that size is little, cost is low, high reliability, have a wide range of applications in fields such as consumer electronics product, automotive electronics, Industry Control and national defence.Micro-mechanical accelerometer can be divided into pressure resistance type, piezoelectric type, tunnel type, condenser type etc. again by Cleaning Principle.Wherein, resistance-type accelerometer has the advantages such as interface circuit is simple, antijamming capability is strong, processing technology is simple.
Body micro mechanical technology is the common method making piezoresistance type acceleration sensor.Body micromechanics piezoresistance type acceleration sensor adopts sandwich structure.So-called sandwich structure is made up of three-decker: upper cover plate, movable sensitive structure and lower cover.Wherein movable sensitive structure adopts beam-mass block structure, namely supports mass block structure by several beam, beam makes force sensing resistance, when there being acceleration, mass produces displacement makes beam bend, thus produces stress on beam, measures stress just can obtain accekeration by force sensing resistance.Upper and lower cover plates provides protection for movable structure, and upper and lower cover plates also makes position limiting structure, and during restriction high overload, the displacement of mass, avoids structural failure.
Sensitivity and bandwidth are characterize the static characteristics of acceleration transducer and the important indicator of dynamic perfromance respectively.But there is contradiction in the requirement of this two indices to structure.In general, the structure coefficient of stiffiness is less, mass quality is larger, then sensitivity is higher, bandwidth is lower; On the contrary, the structure coefficient of stiffiness is larger, mass quality is less, then sensitivity is lower, bandwidth is higher.Therefore, the general figure of merit of product as acceleration transducer adopting sensitivity and bandwidth.The figure of merit is higher, then combination property is better.
For piezoresistance type acceleration sensor, sensitivity is directly proportional to beam upper surface maximum stress, and bandwidth is directly proportional to mesomerism circular frequency, therefore can use the figure of merit S of product as sensitive structure of beam upper surface maximum stress and resonant frequency
tf.For the sensitive structure of two-end fixed beam-mass block structure, its figure of merit S
tfbe similar to and be directly proportional to the square root of mass and beam volume ratio:
Because the minimum dimension of beam is determined by process conditions, be difficult to reduce.When size sensor reduces, figure of merit S
tfalso reduce.More seriously, resonant frequency increases with structure scaled down, when size sensor reduces, in order to ensure sensitivity and resonant frequency in the reasonable scope, suitably must increase the size of beam, causing figure of merit S
tffurther reduction.Therefore, sensitive structure is optimized to improve the S of structure
tfthe figure of merit is a challenge of acceleration transducer design.
Another design difficulty of acceleration transducer is the suppression to paraxonic sensitivity.Acceleration is vector, there is x, y and z tri-components, ideally single-axis acceleration sensors should be only responsive to one-component, but practical devices is generally all responsive to three components, suppressing as far as possible is another subject matter of sensor design to the sensitivity not needing component (paraxonic sensitivity).
The Stress match of sensitive structure is also the design difficulty of acceleration transducer.Beam mass sensitive structure counter stress is responsive.When beam surface exists oxide layer, the thermal stress in oxide layer can cause structure to have the flexure of micron dimension, causes device performance to decline and even loses efficacy.Conventional method first uses bulk silicon micromachining technology thinning to beam district, then make force sensing resistance, structurally can form symmetrical oxide layer by lower surface like this, realize Stress match.But the poor compatibility of the method and integrated circuit technology.General integrated circuit factory does not provide bulk silicon micromachining service, does not allow the silicon chip having carried out bulk silicon micromachining to enter factory yet.Therefore desirable work flow is the processing first carrying out force sensing resistance electric bridge in integrated circuit foundries, then carries out bulk silicon micromachining.And this flow process must solve Stress match problem from structure.
Utility model content
The shortcoming of prior art in view of the above, the purpose of this utility model is to provide a kind of piezoresistance type acceleration sensor and preparation method thereof, low and produce the problem of sensitive reaction to paraxonic to easy and overcome the difficulty of conventional acceleration sensor Stress match difference for solving the figure of merit of acceleration transducer in prior art.
For achieving the above object and other relevant objects, the utility model provides a kind of piezoresistance type acceleration sensor, and described piezoresistance type acceleration sensor at least comprises: sensitive structure; Be bonded to the upper cover plate in this sensitive structure front and the lower cover at the back side thereof respectively; Described sensitive structure comprises: rectangle outer rim, be positioned at the mass of described rectangle outer rim center; Described mass is symmetrical respectively relative to two groups of opposite side of described rectangle outer rim; The left and right sides of described mass is respectively equipped with two and fixes and be connected to the brace summer between described mass and rectangle outer rim; Four sensitive beam be connected between described mass and described rectangle outer rim are provided with between two described brace summers of every side, the described mass left and right sides; Described sensitive beam, mass and rectangle outer rim upper surface are separately positioned at same plane; The more described brace summer of described sensitive beam more integrated distribution near described mass central axis in left-right direction; Being positioned at described four sensitive beam of described mass the same side, is that one group of described central axis each other about described mass is symmetrical between two; The head of described each sensitive beam or afterbody are respectively equipped with a force sensing resistance; With the position consistency of force sensing resistance in respective sensitive beam in four sensitive beam that the described central axis of described mass is nearest; With the position consistency of force sensing resistance in respective sensitive beam in the described central axis distance of described mass four sensitive beam farthest; Described brace summer and described sensitive beam lower surface be separately positioned at same plane and the upper surface of described brace summer lower than the upper surface of described sensitive beam; The width of described sensitive beam is much smaller than the width of described brace summer; Described each sensitive beam is provided with the metal lead wire connecting force sensing resistance two ends in this sensitive beam; The width of described sensitive beam is slightly wider than the width of described force sensing resistance and metal lead wire.
Preferably, the described force sensing resistance in nearest with the described central axis of described mass described four sensitive beam is positioned at the head position of each sensitive beam being close to this mass; The tail position of each sensitive beam away from this mass is positioned at the described force sensing resistance in the described central axis distance of described mass described four sensitive beam farthest.
Preferably, the described force sensing resistance in nearest with the described central axis of described mass described four sensitive beam is positioned at the tail position of each sensitive beam away from this mass; The head position of each sensitive beam being close to this mass is positioned at the described force sensing resistance in the described central axis distance of described mass described four sensitive beam farthest.
Preferably, the upper surface of described sensitive beam is provided with oxide layer; The upper surface non-oxidation layer of described brace summer.
Preferably, described upper cover plate and lower cover are bonded to upper surface and the lower surface of described rectangle outer rim respectively; Space below described mass and between described lower cover is provided with the buffer stopper being positioned at described lower cover.
The utility model also provides a kind of method for making of piezoresistance type acceleration sensor, and this method for making at least comprises: (1) provides a silicon base, and makes described force sensing resistance in the front of described silicon base; (2) corrosion barrier layer is made respectively at the front and back of this silicon base; (3) etch the described corrosion barrier layer at the described silicon base back side to exposing the described silicon base back side, form corrosion window; (4) corrode the described silicon base back side until the thickness of the remaining silicon fiml of corrosion area is the thickness of described sensitive beam along described corrosion window, form the back side of described sensitive structure, the part that is not corroded forms described mass; (5) the described metal lead wire being connected to described force sensing resistance two ends is made in the front of described sensitive structure; (6) make described lower cover and described lower cover be bonded to the back side of described sensitive structure; (7) etch the described metal lead wire both sides in thinning described silicon base front, form concave regions, the thickness of described concave regions is the thickness of described brace summer; (8) penetrate described silicon base front, form the front of the described sensitive structure be made up of the described rectangle outer rim, brace summer, sensitive beam and the mass that are separated from each other; (9) make described upper cover plate and described upper cover plate be bonded to the front of described sensitive structure, after the scribing of described rectangle outer rim, forming described piezoresistance type acceleration sensor.
Preferably, the described corrosion barrier layer in described step (2) is monox, silicon nitride composite bed.
Preferably, in described step (4), the corrosive liquid at the described silicon base back side of corrosion is alkaline anisotropic corrosive liquid.
Preferably, described alkaline anisotropic corrosive liquid comprises KOH, TMAH corrosive liquid.
Preferably, the method that in described step (7), the thinning described metal lead wire both sides of etching form described concave regions is deep reaction ion etching method; The method penetrating described silicon base front in described step (8) is deep reaction ion etching method.
As mentioned above, piezoresistance type acceleration sensor of the present utility model and preparation method thereof, there is following beneficial effect: the utility model adopts wide and thin brace summer and narrow and thick sensitive beam common support mass, utilize the large feature of narrow and thick sensitive beam moment of inertia to realize stress to concentrate, can significantly reduce sensitive beam on the impact of the structure coefficient of stiffiness thus improve the figure of merit.Sensitive beam to be produced near structure center line and to realize the suppression to paraxonic sensitivity in conjunction with electric bridge connected mode.Sensitive beam flexure of the present utility model is less, can reduce paraxonic sensitivity; Brace summer is near mass edge, and its arm of force is long, and the mass that can paraxonic acceleration be suppressed better to cause reverses around center line; Brace summer upper surface is lower than mass and frame, and surface does not have oxide layer, can reduce the structural deflection that oxide layer stress causes.The thickness of brace summer is thin, can reduce the structure coefficient of stiffiness, improves sensitivity and the figure of merit.
Accompanying drawing explanation
Fig. 1 is shown as piezoresistance type acceleration sensor sensitive structure schematic diagram of the present utility model.
Fig. 2 is shown as sensitive structure schematic top plan view of the present utility model.
Fig. 3 is shown as the connection diagram of metal lead wire of the present utility model and force sensing resistance.
Fig. 4 is shown as the electric bridge connected mode schematic diagram of force sensing resistance of the present utility model.
Fig. 5 a to Fig. 5 e is shown as the production process structural representation of piezoresistance type acceleration sensor of the present utility model.
Element numbers explanation
11 upper cover plates
12 lower covers
101 rectangle outer rim
102 masses
103 brace summers
104 sensitive beam
105 force sensing resistances
106 metal lead wires
13 silicon base
131 corrosion barrier layers
Embodiment
Below by way of specific instantiation, embodiment of the present utility model is described, those skilled in the art the content disclosed by this instructions can understand other advantages of the present utility model and effect easily.The utility model can also be implemented or be applied by embodiments different in addition, and the every details in this instructions also can based on different viewpoints and application, carries out various modification or change not deviating under spirit of the present utility model.
Refer to Fig. 1 to Fig. 5 e.It should be noted that, the diagram provided in the present embodiment only illustrates basic conception of the present utility model in a schematic way, then only the assembly relevant with the utility model is shown in graphic but not component count, shape and size when implementing according to reality is drawn, it is actual when implementing, and the kenel of each assembly, quantity and ratio can be a kind of change arbitrarily, and its assembly layout kenel also may be more complicated.
Described piezoresistance type acceleration sensor of the present utility model at least comprises: sensitive structure, upper cover plate and lower cover, and described upper cover plate is bonded in the front of described sensitive structure, and described lower cover is bonded in the back side of described sensitive structure.As shown in Figure 1, Fig. 1 is shown as piezoresistance type acceleration sensor sensitive structure schematic diagram of the present utility model.Described sensitive structure in the present embodiment comprises: rectangle outer rim 101, mass 102, as shown in Figure 1, described mass 102 is positioned at the center of described rectangle outer rim 101 inside, and described mass 102 is symmetrical respectively relative to two groups of opposite side of described rectangle outer rim 101; Preferably, the xsect of described mass 102 is rectangle, and as shown in the figure, two groups of opposite side of described mass 102 xsect are parallel with two groups of opposite side of described rectangle outer rim 101 respectively.Preferably, described upper cover plate 11 and lower cover 12 are bonded to upper surface and the lower surface of described rectangle outer rim 101 respectively.Described sensitive structure also comprises brace summer 103, as shown in Figure 1, the left and right sides of described mass 102 is respectively equipped with two and fixes and be connected to the brace summer 103 between described mass 102 and rectangle outer rim 101, two brace summers 103 of the every side of described mass 102 are symmetrical respectively with two brace summers 103 of opposite side, such as, in Fig. 1, on the left of described mass 102 top brace summer 103 and mass 102 on the right side of the brace summer 103 of top be on same straight line, and this straight line parallel is in the center line (dotted line in Fig. 1) of described mass 102 at left and right directions, brace summer 103 and the bottom-right brace summer of mass 102 103 of mass 102 lower left are in same straight line, and this straight line is also parallel to the center line of described mass 102 at left and right directions.
Described sensor of the present utility model also comprises the sensitive beam 104 be arranged between described brace summer 103, as shown in Figure 1, four sensitive beam 104 be connected between described mass 102 and described rectangle outer rim 101 are provided with between two described brace summers 103 of every side, described mass 102 left and right sides, four sensitive beam 104 between two brace summers 103 on the left of described mass 102 are spaced parallel arranged, and four described sensitive beam 104 are in same plane; Four sensitive beam 104 between same two brace summers 103 on the right side of described mass 102 are spaced parallel arranged, and four described sensitive beam 104 are in same plane.As shown in Figure 1, in the utility model, the respective upper surface of described sensitive beam 104, mass 102 and rectangle outer rim 101 is positioned at same plane.In the utility model, the more described brace summer of described sensitive beam 104 103 being arranged in described mass 102 the same side more integrated distribution in described mass 102 center in left-right direction (dotted line of Fig. 1) near axis; That is, four sensitive beam 104 distance each other on the left of described mass 102 is less than the distance between sensitive beam 104 that the upper left brace summer 103 of this mass 102 is adjacent position, the distance being adjacent the sensitive beam 104 of position at the brace summer 103 of described mass 102 lower left equals the distance between sensitive beam 104 that the upper left brace summer 103 of mass 102 is adjacent position, and the position relationship between the brace summer 103 on the right side of described mass 102 and sensitive beam 104 and each sensitive beam 104 is also like this.And the position relationship between described mass 102 and described sensitive beam 104 is: described four sensitive beam 104 being positioned at described mass 102 the same side, be that one group of described central axis (dotted line in Fig. 1) each other about described mass 102 is symmetrical between two.Preferably, parallel to each other and the distance between adjacent sensitive beam 104 of each sensitive beam 104 on the left of described mass 102 is equal to each other, the position relationship being each other positioned at four sensitive beam 104 on the right side of described mass 102 is also like this, and the sensitive beam 104 be positioned on the left of described mass 102 is symmetrical with the sensitive beam 104 be positioned on the right side of this mass 102.
As shown in Figure 2, Fig. 2 is shown as sensitive structure schematic top plan view of the present utility model.Head or the afterbody of described each sensitive beam 104 of the present utility model are respectively equipped with a force sensing resistance 105, with the position consistency of force sensing resistance 105 in respective sensitive beam 104 in four sensitive beam 104 that the described central axis (dotted line in Fig. 1) of described mass 102 is nearest; With the position consistency of force sensing resistance 105 in respective sensitive beam 104 in the described central axis distance of described mass 102 four sensitive beam 104 farthest, that is, as in Fig. 2, be arranged in the sensitive beam 104 on the left of described mass 102, the force sensing resistance 105 in two wherein middle sensitive beam 104 and the position consistency of force sensing resistance 105 in respective sensitive beam 104 be arranged in two sensitive beam 104 of the bright sensitive beam 104 middle (central axis both sides) on the right side of described mass 102; To be positioned on the left of described mass 102 on the right side of force sensing resistance 105 in two sensitive beam 104 at most edge (adjacent with described brace summer 103) and mass 102 position consistency of force sensing resistance 105 in respective described sensitive beam 104 in two sensitive beam 104 at most edge equally.In the present embodiment, so-called positional representation in described sensitive beam 104 is the head or the afterbody that are positioned at this sensitive beam 104, head refers to this sensitive beam 104 one end near described mass 102, and afterbody refers to one end that this sensitive beam 104 is connected with described rectangle outer rim 101.
A kind of preferred version of the present utility model is, as shown in Figure 2, the described force sensing resistance 105 that nearest with the described central axis of described mass 102 described four sensitive beam 104 (are positioned at middle each two sensitive beam 104 of mass 102 left and right sides) is positioned at the head position of each sensitive beam 104 being close to this mass 102; The tail position of each sensitive beam 104 away from this mass 102 is positioned at the described force sensing resistance 105 in described four sensitive beam 104 of the described central axis distance of described mass 102 (each two sensitive beam 104 at edge, mass 102 left and right sides) farthest.Another kind of preferred version of the present utility model is, is positioned at the tail position of each sensitive beam 104 away from this mass 102 with the described force sensing resistance 105 in described four sensitive beam 104 (being positioned at middle each two sensitive beam 104 of mass 102 left and right sides) that the described central axis of described mass 102 is nearest; The head position of each sensitive beam 104 being close to this mass 102 is positioned at the described force sensing resistance 105 in described four sensitive beam 104 of the described central axis distance of described mass 102 (each two sensitive beam 104 at edge, mass 102 left and right sides) farthest.Preferably, the upper surface of described sensitive beam 104 has oxide layer to cover simultaneously; The upper surface non-oxidation layer of described brace summer 103 covers.
As shown in Figure 1, the lower surface that described brace summer 103 is respective with described sensitive beam 104 be positioned at same plane and the upper surface of described brace summer 103 lower than the upper surface of described sensitive beam 104; The width of described sensitive beam 104 is much smaller than the width of described brace summer 103; As shown in Figure 3, Fig. 3 is shown as the connection diagram of metal lead wire 106 of the present utility model and force sensing resistance 105.Described each sensitive beam 104 is provided with the metal lead wire 106 connecting force sensing resistance 105 two ends in this sensitive beam 104; The width of described sensitive beam 104 is slightly wider than the width of described force sensing resistance 105 and metal lead wire 106.
In the utility model, each force sensing resistance 105 is interconnected to form electric bridge, and as shown in Figure 4, Fig. 4 is shown as the electric bridge connected mode schematic diagram of force sensing resistance 105 of the present utility model.In Fig. 2, represent each force sensing resistance 105 with R1 to R8, four force sensing resistances 105 be wherein positioned on the left of described mass 102 are expressed as R1, R2, R1, R5 from top to bottom successively; Four force sensing resistances 105 be positioned on the right side of described mass 102 are expressed as R4, R3, R7, R8 from top to bottom successively.The electric bridge that described in each, force sensing resistance 105 connects into is as shown in Figure 4: wherein R2, R7, R8, R1 are connected in series mutually; R5, R4, R3, R6 are connected in series mutually (tandem of each force sensing resistance 105 is through the metal lead wire 106 be positioned in respective sensitive beam 104 and is connected in series), R2 and R5 is interconnected in supply voltage; R1 and R6 is interconnected and ground connection; Between R7 and R8, be provided with output terminal simultaneously, between R4 and R3, be provided with output terminal.These two output terminals are for measuring output voltage.
The principle of work of described piezoresistance type acceleration sensor of the present utility model with working method is: suppose that described mass 102 is subject to the acceleration vertical with its surface; Sensitive beam 104 is subject to stress due to acceleration thus causes the force sensing resistance 105 be positioned in described each sensitive beam 104 that the change of resistance value occurs, because increased resistance value is directly proportional to the stress be subject to the ratio of former resistance value, and stress directly can reflect suffered acceleration magnitude; Therefore, the size of increased resistance value can be directly used in the size of reflection acceleration.And actual conditions are, mass 102 is not generally the acceleration being subject to merely its surface vertical, and in fact acceleration in the horizontal direction also can be important, therefore, in order to offset the sensitivity of acceleration transducer to paraxonic, each force sensing resistance 105 designs electric bridge method of attachment as above, and this connected mode can offset this piezoresistance type acceleration sensor acceleration in the horizontal direction, only calculates the effective acceleration in vertical direction.As previously mentioned, the change in resistance of force sensing resistance 105 directly can reflect the size of normal acceleration, therefore in test electric bridge, the change in voltage of two described output terminals can the change of direct reflected resistance, and the change in voltage of two output terminals namely tested out just can be directly changed into the size of acceleration in vertical direction.
The utility model also provides the method for making based on the above piezoresistance type acceleration sensor, in the present embodiment, this method for making comprises the following steps: as shown in Fig. 5 a to Fig. 5 d, and Fig. 5 a to Fig. 5 d is shown as the production process structural representation of piezoresistance type acceleration sensor of the present utility model.
Step one: as shown in Figure 5 a, provides a silicon base 13, and makes described force sensing resistance 105 in the front of described silicon base 13; The described force sensing resistance 105 made is eight force sensing resistances 105 as shown in Figure 2.
Step 2: in Fig. 5 a, makes corrosion barrier layer 131 respectively at the front and back of this silicon base 13, and preferably, described corrosion barrier layer 131 is monox, silicon nitride composite bed.
Step 3: etch the described corrosion barrier layer 131 at described silicon base 13 back side to exposing described silicon base 13 back side, forms corrosion window.
Then implementation step four: as shown in Figure 5 b, described silicon base 13 back side is corroded until the thickness of the remaining silicon fiml of corrosion area is the thickness of described sensitive beam 104 along described corrosion window, form the back side of described sensitive structure, the part that is not corroded forms described mass 102; Preferably, the corrosive liquid corroding described silicon base 13 back side is alkaline anisotropic corrosive liquid.Further preferably; in the present embodiment; described alkaline anisotropic corrosive liquid comprises the corrosive liquids such as KOH, TMAH; the described alkaline anisotropic corrosive liquid that the utility model adopts is not limited to KOH, TMAH corrosive liquid, and other various alkaline anisotropic corrosive liquids except KOH, TMAH corrosive liquid also all drop within the utility model scope required for protection.
Step 5: as shown in Figure 5 c, the described metal lead wire 106 being connected to described force sensing resistance 105 two ends is made in the front of described sensitive structure, as shown in Figure 3, the width of the metal lead wire 106 of making should be less than the width of described sensitive beam 104 to the width of made metal lead wire 106.Then implementation step six: as fig 5d, make described lower cover 12 and described lower cover 12 be bonded to the back side of described sensitive structure, preferably, the space below described mass 102 and between described lower cover 12 is provided with the buffer stopper being positioned at described lower cover 12.The effect of described lower cover 12 is for described sensitive structure provides protection, and the effect of described buffer stopper is in restriction high overload situation, and the displacement of mass 102 is too large, avoids structural failure.
Step 7: described metal lead wire 106 both sides etching thinning described silicon base 13 front, form concave regions, the thickness of described concave regions silicon is the thickness of described brace summer 103, that is, as shown in Figure 1, the upper surface of described brace summer 103 will lower than the upper surface of described sensitive beam 104, the corrosion barrier layer 131 of described brace summer 103 upper surface is etched and removes simultaneously, therefore, the oxide layer that do not have of described brace summer 103 upper surface covers, and described sensitive beam 104 upper surface is not owing to being etched, therefore, the upper surface of described sensitive beam 104 is provided with oxide layer.Further preferably, etching the method that thinning described metal lead wire 106 both sides form described concave regions is deep reaction ion etching method.
Step 8: penetrate described silicon base 13 front, form the front of the described sensitive structure be made up of the described rectangle outer rim 101, brace summer 103, sensitive beam 104 and the mass 102 that are separated from each other, the front of the described sensitive structure of formation as shown in Figure 2.Wherein preferably, the method penetrating described silicon base 13 front is deep reaction ion etching method.
Step 9: as depicted in fig. 5e, makes described upper cover plate 11 and described upper cover plate 11 is bonded to the front of described sensitive structure, after the scribing of described rectangle outer rim 101, forming described piezoresistance type acceleration sensor.So far, described piezoresistance type acceleration sensor of the present utility model is defined.
In sum, the utility model adopts wide and thin brace summer and narrow and thick sensitive beam common support mass, utilize the large feature of narrow and thick sensitive beam moment of inertia to realize stress to concentrate, can significantly reduce sensitive beam on the impact of the structure coefficient of stiffiness thus improve the figure of merit.Sensitive beam to be produced near structure center line and to realize the suppression to paraxonic sensitivity in conjunction with electric bridge connected mode.Sensitive beam flexure of the present utility model is less, can reduce paraxonic sensitivity; Brace summer is near mass edge, and its arm of force is long, and the mass that can paraxonic acceleration be suppressed better to cause reverses around center line; Brace summer upper surface is lower than mass and frame, and surface does not have oxide layer, can reduce the structural deflection that oxide layer stress causes.The thickness of brace summer is thin, can reduce the structure coefficient of stiffiness, improves sensitivity and the figure of merit.So the utility model effectively overcomes various shortcoming of the prior art and tool high industrial utilization.
Above-described embodiment is illustrative principle of the present utility model and effect thereof only, but not for limiting the utility model.Any person skilled in the art scholar all without prejudice under spirit of the present utility model and category, can modify above-described embodiment or changes.Therefore, such as have in art and usually know that the knowledgeable modifies or changes not departing from all equivalences completed under the spirit and technological thought that the utility model discloses, must be contained by claim of the present utility model.
Claims (5)
1. a piezoresistance type acceleration sensor, is characterized in that, described piezoresistance type acceleration sensor at least comprises:
Sensitive structure; Be bonded to the upper cover plate in this sensitive structure front and the lower cover at the back side thereof respectively;
Described sensitive structure comprises: rectangle outer rim, be positioned at the mass of described rectangle outer rim center; Described mass is symmetrical respectively relative to two groups of opposite side of described rectangle outer rim; The left and right sides of described mass is respectively equipped with two and fixes and be connected to the brace summer between described mass and rectangle outer rim;
Four sensitive beam be connected between described mass and described rectangle outer rim are provided with between two described brace summers of every side, the described mass left and right sides; Described sensitive beam, mass and rectangle outer rim upper surface are separately positioned at same plane; The more described brace summer of described sensitive beam being positioned at described mass the same side more integrated distribution near described mass central axis in left-right direction; Being positioned at described four sensitive beam of described mass the same side, is that one group of described central axis each other about described mass is symmetrical between two;
The head of described each sensitive beam or afterbody are respectively equipped with a force sensing resistance; With the position consistency of force sensing resistance in respective sensitive beam in four sensitive beam that the described central axis of described mass is nearest; With the position consistency of force sensing resistance in respective sensitive beam in the described central axis distance of described mass four sensitive beam farthest;
Described brace summer and described sensitive beam lower surface be separately positioned at same plane and the upper surface of described brace summer lower than the upper surface of described sensitive beam; The width of described sensitive beam is much smaller than the width of described brace summer; Described each sensitive beam is provided with the metal lead wire connecting force sensing resistance two ends in this sensitive beam; The width of described sensitive beam is slightly wider than the width of described force sensing resistance and metal lead wire.
2. piezoresistance type acceleration sensor according to claim 1, is characterized in that: be positioned at the head position of each sensitive beam being close to this mass with the described force sensing resistance in described four sensitive beam that the described central axis of described mass is nearest; The tail position of each sensitive beam away from this mass is positioned at the described force sensing resistance in the described central axis distance of described mass described four sensitive beam farthest.
3. piezoresistance type acceleration sensor according to claim 1, is characterized in that: be positioned at the tail position of each sensitive beam away from this mass with the described force sensing resistance in described four sensitive beam that the described central axis of described mass is nearest; The head position of each sensitive beam being close to this mass is positioned at the described force sensing resistance in the described central axis distance of described mass described four sensitive beam farthest.
4. piezoresistance type acceleration sensor according to claim 1, is characterized in that: the upper surface of described sensitive beam is provided with oxide layer; The upper surface non-oxidation layer of described brace summer.
5. piezoresistance type acceleration sensor according to claim 1, is characterized in that: described upper cover plate and lower cover are bonded to upper surface and the lower surface of described rectangle outer rim respectively; Space below described mass and between described lower cover is provided with the buffer stopper being positioned at described lower cover.
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| CN201420837962.8U CN204330809U (en) | 2014-12-19 | 2014-12-19 | A kind of piezoresistance type acceleration sensor |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105785073A (en) * | 2014-12-19 | 2016-07-20 | 中国科学院上海微系统与信息技术研究所 | Piezoresistive acceleration sensor and manufacturing method thereof |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105785073A (en) * | 2014-12-19 | 2016-07-20 | 中国科学院上海微系统与信息技术研究所 | Piezoresistive acceleration sensor and manufacturing method thereof |
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