JP2011247714A - Semiconductor physical quantity sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a semiconductor physical quantity sensor which is capable of more suppressing the occurrence of sticking by reducing a contact area between opposite wall parts of a stopper and the other party side.SOLUTION: Opposite wall parts 64b and 5c of a stopper 64a and a movable part 5 are formed so as to be, in a cross-sectional view along a depth direction of a gap part δ5, symmetrical with respect to a line connecting apexes Sp and Tp provided in positions nearer to each other than respective upper ends Su and Tu and lower ends Sd and Td of virtual perpendicular surfaces Sw and Tw opposite to each other, within ranges from the upper ends Su and Tu to lower ends Sd and Td.

Description

  The present invention relates to a semiconductor physical quantity sensor.

  Conventionally, in a semiconductor physical quantity sensor such as an acceleration sensor, the movable part operates to operate the fixed part when an excessive physical quantity is input during the manufacturing process of forming a gap in the silicon substrate by etching or during operation of the sensor. So-called sticking that sticks to the surface is regarded as a problem.

  Therefore, by forming a stopper on one of the opposing wall portions of the movable portion and the fixed portion and bringing the stopper into contact with the opposing wall portion on the other side, the contact area is reduced to suppress the sticking. Is known (for example, see Patent Document 1).

JP 2001-330623 A

  However, in the above-described conventional semiconductor physical quantity sensor, the occurrence of sticking can be suppressed by the stopper, but it is still more preferable to reduce the contact area.

  SUMMARY OF THE INVENTION An object of the present invention is to obtain a semiconductor physical quantity sensor that can suppress the occurrence of sticking by reducing the contact area between the stopper and the opposing wall portion on the other side.

  In order to solve such a problem, in the present invention, by forming a gap in the semiconductor substrate by etching, a movable portion and a fixed portion that are relatively displaced by an input of a physical quantity are formed, and the movable portion and In the semiconductor physical quantity sensor, in which at least one of the opposing wall portions of the fixed portion is formed with a stopper protruding toward the other side, a cross section of the stopper and the opposite side opposing wall portion along the depth direction of the gap portion. From the upper end and the lower end of the virtual vertical surfaces facing each other, the shape of the line is symmetrical with the apex provided at a position approaching or separating from the other side within the range of the upper end and the lower end. It was formed as described above.

  According to the present invention, since the contact area in the same cross-sectional view can be reduced as compared with the conventional case, the contact area between the stopper and the opposing wall portion on the other side is easily reduced, and the occurrence of sticking is further suppressed. Can do.

It is an internal top view which shows typically the semiconductor physical quantity sensor concerning 1st Embodiment of this invention. It is an enlarged view of the B section in FIG. It is an expanded sectional view of the C section in FIG. FIG. 3 is a perspective view of a stopper in FIG. 2. The state in which the stopper and the opposing wall on the other side are in contact is schematically shown in order in (a), (b), (c), (a) is the state before contact, and (b) is the state in contact. (C) is sectional drawing which showed the state after contacting. It is an expanded sectional view of the same position as the C section in Drawing 2 in the semiconductor physical quantity sensor concerning a 2nd embodiment of the present invention. It is a perspective view of the stopper shown in FIG. The state in which the stopper and the opposing wall on the other side are in contact is schematically shown in order in (a), (b), (c), (a) is the state before contact, and (b) is the state in contact. (C) is sectional drawing which showed the state after contacting.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Hereinafter, as the semiconductor physical quantity sensor, a biaxial acceleration sensor capable of detecting accelerations in the X-axis and Y-axis directions perpendicular to each other will be exemplified. Note that similar components are included in the following embodiments. Therefore, in the following, common reference numerals are given to those similar components, and redundant description is omitted.

[First Embodiment]
FIGS. 1-5 is the figure which showed the acceleration sensor 1 concerning 1st Embodiment of this invention.

  The acceleration sensor 1 of the present embodiment includes a silicon substrate (semiconductor substrate) 3 having a substantially square shape on which semiconductor element devices are formed, sandwiched between two glass substrates (not shown) serving as protective layers thereof, For example, the substrate 3 and the glass substrate are integrally bonded by anodic bonding or the like.

  As shown in FIG. 1, the silicon substrate 3 is formed with a plurality of gaps δ1 to δ5 having different widths by a known semiconductor process, thereby forming a substantially rectangular frame portion formed at the peripheral portion. 2, a movable portion 5, a fixed portion 6, a beam (spring portion) 8, and a support portion 9 that supports the movable portion 5 via the beam (spring portion) 8 are formed. A relatively shallow recess (not shown) is formed on the bonding surface between the silicon substrate 3 and the glass substrate, so that insulation of each part of the silicon substrate 3 and operability of the movable part 5 are ensured. .

  The gaps δ1 to δ4 are formed so that the side wall surface is perpendicular to the surface of the silicon substrate 3 by performing vertical etching processing such as reactive ion etching (RIE). Thus, the side wall surfaces of the gaps δ1 to δ4 formed by the vertical etching process face each other substantially in parallel. As reactive ion etching, for example, ICP processing by an etching apparatus provided with inductively coupled plasma (ICP) can be used.

  The frame portion 2 and the support portion 9 are extended in a frame shape with a substantially constant width along the four peripheral edges (four sides) of the silicon substrate 3. And the support part 9 is arrange | positioned on the inner peripheral side of the frame part 2 in the state isolated by the substantially frame-shaped gap | interval part (delta) 3. In addition, this frame part 2 and the support part 9 are fixed to a glass substrate by joining a back surface side to the surface of a glass substrate (not shown).

  Four beams 8 extending in a spiral shape toward the center are provided inside the support portion 9 from the four corners of the support portion 9 in parallel with each side of the support portion 9 and at right angles in the middle. . The beam 8 extends over two sides of the support portion 9 without interfering with each other, and is connected to a corner of the movable portion 5 at the inner end portion. 5 functions as a spring element (spiral spring) that elastically and movably supports 5.

  That is, in the present embodiment, the movable portion 5 is provided with a function as a mass element (mass) that is movably supported by the beam 8 as a spring element, and a spring-mass system is configured by the spring element and the mass element. The acceleration and angular acceleration can be obtained from the displacement of the movable part 5 as a mass element.

  And in order to detect the displacement of this movable part 5, in this embodiment, the movable electrode provided in the movable part 5 and the fixed electrode provided in the fixed part 6 are arranged opposite to each other with gaps δ1, δ2. The detection part 7 is comprised. By detecting the electrostatic capacitance between the movable electrode and the fixed electrode in the detection unit 7, the change of the gaps δ1, δ2, that is, the displacement of the fixed electrode with respect to the movable electrode is detected.

  Specifically, as shown in FIG. 1, the movable portion 5 has a comb-like movable shape extending in a strip shape in a direction substantially perpendicular to the side from the central portion 5 a toward the central portion of each side of the support portion 9. An electrode 51 is provided. In the present embodiment, the plurality of movable side comb teeth 51a are provided in parallel to each other at a constant pitch.

  On the other hand, the fixed portion 6 includes an anchor portion 63 provided adjacent to the corner portion 5 b of the movable portion 5, and the anchor portion 63 is an edge portion 63 a that extends in a strip shape along each side of the support portion 9. It has. A comb-like fixed electrode 61 extending toward the central portion 5a side of the movable portion 5 is connected to the edge portion 63a. In the present embodiment, the plurality of fixed side comb teeth 61a are provided in parallel with each other at a constant pitch (the same pitch as the movable side comb teeth 51a of the movable portion 5), and the plurality of movable sides of the movable portion 5 are movable. The comb teeth 51a and the gaps δ1 and δ2 are engaged with each other.

  In the detection unit 7, the gaps δ1 and δ2 between the movable comb teeth 51a and the fixed comb teeth 61a are narrower on one side (gap portion δ2) and wider on the other side (gap portion δ1). (Δ1> δ2), with the gap δ2 on the narrow side as a detection gap, the capacitance between the comb teeth 51 and 61 facing each other through the gap δ2, that is, the fixed electrode and the movable electrode The capacitance between the two is detected.

  As shown in FIG. 1, the detection unit 7 is provided corresponding to the center of each side of the frame unit 2, and includes a detection unit 7 </ b> X for detecting the X direction (upper and lower detection units in FIG. 1) and the Y direction. Two detection portions 7Y for detection (left and right detection portions in FIG. 1) are provided.

  The comb-like fixed electrode 61 is fixed to a glass substrate (not shown) via the anchor portion 63. At this time, the anchor part 63 and the support part 9 are insulated from each other. The support part 9 is provided with one electrode 5E for external extraction, and the anchor part 63 is provided with the other electrodes 6E1 and 6E2.

  The capacitance change when the gaps δ1 and δ2 between the comb-like movable electrode 51 and the comb-like fixed comb electrode 61 are changed by the input of the acceleration (physical quantity) in the X-axis direction is changed to the electrode 5E. , The acceleration in the X-axis direction can be detected by processing from 6E1. Further, the capacitance change when the gaps δ1 and δ2 between the comb-like movable electrode 51 and the comb-like fixed electrode 61 are changed by inputting the acceleration in the Y-axis direction is taken out from the electrodes 5E and 6E2. By processing, the acceleration in the Y-axis direction can be detected.

  Here, in this embodiment, a sub-anchor portion 64 for a stopper is provided on the side of the anchor portion 63 adjacent to the anchor portion 63, and the sub-anchor portion 64 is also used as the fixing portion 6 in the glass substrate. (Not shown).

  As shown in FIG. 2, the sub-anchor portion 64 is provided with a protruding stopper 64 a that extends along the X-axis direction and the Y-axis direction and protrudes toward the movable portion 5. In this embodiment, the stopper 64a that protrudes toward the movable portion 5 is formed on the sub-anchor portion 64 as the fixed portion 6. However, the stopper 64a that protrudes toward the sub-anchor portion 64 is provided on the movable portion 5. It may be.

  As described above, in the present embodiment, by providing the sub-anchor portion 64 with the protruding stopper 64a, when a predetermined acceleration is input or when the movable portion 5 is greatly displaced due to an excessive acceleration input, The contact between the comb-like movable electrode 51 and the comb-like fixed electrode 61 is suppressed. Moreover, since the stopper 64 a of the sub-anchor portion 64 is provided at a position facing the movable portion 5 other than the detection portion 7, it is directly connected to the comb-like movable electrode 51 and the comb-like fixed electrode 61 that are the detection portion 7. Compared to the configuration in which the stopper is provided, there is an advantage that breakage and damage of the comb teeth 51 and 61 can be further suppressed. Therefore, in the present embodiment, the gap δ5 between the stopper 64a and the movable part 5 is set to be the smallest among the gaps δ1 to δ5 described above.

  As shown in FIG. 3, in this embodiment, the stopper 64a and the opposing wall portions 64b and 5c of the movable portion 5 are virtual vertical surfaces Sw facing each other in a sectional view along the depth direction of the gap portion δ5. , Lines connecting upper ends Su and Tu and lower ends Sd and Td of Tw to vertices Sp and Tp provided at positions approaching the other side within the range of the upper ends Su and Tu and lower ends Sd and Td, respectively. It is formed so as to have a symmetrical shape.

  Specifically, as shown in FIG. 4, the stopper 64 a of the present embodiment is formed in an arc shape that is gently curved along the width direction of the stopper 64 a that is the surface direction, and in the depth direction thereof. The shape is bent at the apex Sp provided at the substantially central portion. On the other hand, the counterpart movable portion 5 has a vertex Tp at a substantially central portion in the depth direction, and a flat inclined surface protrudes toward the stopper 64a without being curved along the surface direction. It has become a shape. The gap δ5 between the stopper 64a and the movable portion 5 is processed by anisotropic dry etching using ICP etching in the same manner as the gaps δ1 to δ4. In the present embodiment, the stopper 64a is formed in an arc shape that is gently curved along its width direction. It is good also as a shape which protruded the flat inclined surface toward the movable part 5 so that it may become a shape.

  As described above, in this embodiment, the stopper 64a and the opposing wall portions 64b and 5c of the movable portion 5 facing the stopper 64a are bent in a direction in which they approach each other in a sectional view along the depth direction of the gap portion δ5. 5 (a), (b), and (c), when the movable portion 5 operates and hits the stopper 64a, as shown in FIGS. 5 (a), (b), and (c). In addition, as indicated by the D portion in (b), the contact area between the stopper 64a and the opposing wall portions 64b and 5c of the movable portion 5 can be reduced.

  Here, as shown in FIG. 4, the protrusion-shaped stopper 64a formed by etching the silicon substrate 3 is formed with the stopper 64a protruding toward the other side with respect to the depth H of the stopper 64a. In general, the width W is formed small.

  Therefore, as in the present embodiment, the stopper 64a and the opposing wall portions 64b and 5c of the movable portion 5 (mating side) are bent in a direction approaching each other in a sectional view along the depth direction of the gap portion δ5. If formed so as to be (substantially letter-shaped, substantially inverted letter-shaped), the stopper 64a and the movable part 5 (the other side) than the configuration in which the conventional stopper is line-contacted along the depth direction thereof. The contact area of the opposing wall portions 64b and 5c can be further reduced.

  As described above, in the acceleration sensor 1 of the present embodiment, the stopper 64a and the opposing wall portions 64b and 5c of the movable portion 5 (the counterpart side) are mutually viewed in a sectional view along the depth direction of the gap portion δ5. From the upper end portions Su and Tu and the lower end portions Sd and Td of the opposing virtual vertical surfaces Sw and Tw, provided at positions approaching the other party within the range of the upper end portions Su and Tu and the lower end portions Sd and Td. It is formed so as to have a line-symmetric shape connecting the vertices Sp and Tp.

  Therefore, the contact area in the same cross-sectional view can be reduced as compared with the conventional case, so that the contact area between the stopper 64a and the opposing wall portions 64b and 5c of the movable portion 5 (the other side) is easily reduced, and sticking occurs Can be further suppressed. That is, when the movable part 5 operates and hits against the stopper 64a, the spring reaction force can be made larger than these electrostatic attractive forces, and as shown in FIG. Can be restored.

  In particular, in this embodiment, the stopper 64a is formed such that the width W of the stopper 64a protruding toward the other side is smaller than the depth of the stopper 64a. Therefore, the contact area between the stopper 64a and the opposing wall portions 64b and 5c of the movable portion 5 (the counterpart side) can be further reduced as compared with the configuration in which the conventional stopper is in line contact along the depth direction.

  Furthermore, in the present embodiment, the stopper 64a is formed in an arc shape curved along the width direction of the stopper 64a. Therefore, the stopper 64a and the opposing wall portions 64b and 5c of the movable portion 5 (the counterpart side) can be brought into point contact, and the occurrence of sticking can be more reliably suppressed.

[Second Embodiment]
Next, a second embodiment of the present invention will be described with reference to the drawings. 6 is an enlarged cross-sectional view of the acceleration sensor according to the present embodiment at the same position as portion C in FIG. 2, FIG. 7 is a perspective view of the stopper shown in FIG. 6, and FIG. The states are schematically shown in order in (a), (b), and (c), where (a) is the state before contact, (b) is the contact state, and (c) is the state after contact. It is sectional drawing shown.

  In the same manner as in the first embodiment, the acceleration sensor 1 </ b> A of the present embodiment is a projection that protrudes toward the movable portion 105 along the X-axis direction and the Y-axis direction on the sub-anchor portion 164 that is the fixed portion 6. A shaped stopper 164a is provided.

  Here, this embodiment is mainly different from the first embodiment in that the stopper 164a and the opposing wall portions 164b and 105c of the movable portion 105 are opposed to each other in a cross-sectional view along the depth direction of the gap δ5. Vertex Sp provided at a position away from the upper end Su, Tu and lower end Sd, Td of the virtual vertical plane Sw, Tw within the range of the upper end Su, Tu and lower end Sd, Td. , Tp are formed so as to be line symmetrical.

  Specifically, as shown in FIG. 7, the stopper 164 a of the present embodiment is formed in an arc shape that is gently curved along the width direction of the stopper 164 a that is the surface direction, and in the depth direction thereof. The shape is bent at the apex Sp provided at the substantially central portion. On the other hand, the movable portion 105 on the other side has a vertex Tp at a substantially central portion in the depth direction, and the flat inclined surface is not curved along the surface direction, and is separated from the stopper 164a. It has a bent shape. In the present embodiment, the stopper 64a is formed in an arc shape that is gently curved along the width direction thereof. However, like the counterpart movable portion 5, the stopper 64a has a substantially square shape in a sectional view along the depth direction. It is good also as a shape which bent the flat inclined surface in the direction away from the movable part 5 so that it may become.

  With the above configuration, according to the acceleration sensor 1A of the present embodiment, the stopper 164a and the opposing wall portions 164b and 105c of the movable portion 105 facing the stopper 164a are mutually viewed in a sectional view along the depth direction of the gap δ5. Since the shape is bent in a direction away from the other party (substantially reverse letter shape, substantially letter shape), the movable portion 105 operates as shown in FIGS. 8 (a), (b), and (c). Then, when it abuts against the stopper 164a, the contact area between the stopper 164a and the opposing wall portions 164b and 105c of the movable portion 105 can be reduced as indicated by the D portion in (b).

  Accordingly, in the same manner as in the first embodiment, the contact area in the same cross-sectional view can be reduced as compared with the conventional case, so that the contact between the stopper 164a and the opposing wall portions 164b and 105c of the movable portion 105 (the counterpart side). The area can be easily reduced, and the occurrence of sticking can be further suppressed.

  Further, in the present embodiment, as shown in FIG. 8B, when the movable portion 105 is operated, the upper end portions Su and Tu and the lower end portions Sd and Td can be brought into contact with each other. Therefore, there is also an advantage that the contact force between the stopper 164a and the opposing wall portions 164b and 105c of the movable portion 105 (the counterpart side) can be dispersed.

  The preferred embodiments of the present invention have been described above. However, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the gist of the present invention. For example, in the above-described embodiment, the biaxial acceleration sensor is exemplified as the semiconductor physical quantity sensor. However, a uniaxial acceleration sensor or a triaxial acceleration sensor may be used, and other semiconductor physical quantity sensors such as an angular velocity sensor and a vibration sensor may be used. Even if it exists, this invention can be implemented.

  In the above embodiment, the semiconductor physical quantity sensor is exemplified by a three-layer structure (a silicon substrate and two glass substrates). However, a single-layer structure, a two-layer structure, a multilayer structure of four layers or more is used. Is also possible.

  Furthermore, the specifications (shape, size, layout, etc.) of the frame part, the movable part, the fixed part, the spring part, and the support part formed in the semiconductor physical quantity sensor can be changed as appropriate.

1 Acceleration sensor (Semiconductor physical quantity sensor)
3 Silicon substrate (semiconductor substrate)
5 Movable part 5c Opposite wall part 6 Fixed part 64a Stopper 64b Opposite wall part δ1-δ5 Gap part Tw, Sw Vertical surface Tu, Su Upper end part Td, Sd Lower end part Tp, Sp Vertex

Claims (3)

By forming a gap portion in the semiconductor substrate by etching, a movable portion and a fixed portion that are relatively displaced by the input of a physical quantity are formed, and at least one of the opposing wall portions of the movable portion and the fixed portion is on the other side In the semiconductor physical quantity sensor formed with a stopper that protrudes toward
Within the range of the upper end and the lower end from the upper end and the lower end of the virtual vertical surface facing each other, in cross-sectional view along the depth direction of the gap, the opposing wall on the other side of the stopper The semiconductor physical quantity sensor is formed so as to have a line-symmetric shape connecting the vertices provided at positions approaching or separating from each other.   2. The semiconductor physical quantity sensor according to claim 1, wherein the stopper is formed such that a width of the stopper protruding toward the other side is smaller than a depth of the stopper.   The semiconductor physical quantity sensor according to claim 1, wherein the stopper is formed in an arc shape that is curved along a width direction of the stopper.

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