JP2006214963A - Acceleration sensor, electronic equipment, and manufacturing method for acceleration sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To completely separate respective piezoresistance elements mechanically without affecting a support part for supporting a weight part, and hereby prevent a leak current. <P>SOLUTION: This acceleration sensor 10 includes the first substrate 11 and the second substrate 12; an annular weight part 13; a support column part 14 provided substantially in the center of the weight part; the support parts 15 with one end side 15a fixed to a support column part 14 and for supporting the weight part 13 under a suspended condition; fixing parts 17 fixing the other end 15b side of the support part 15; input electrodes 18 capable of impressing a voltage to the support column part 14; the piezoresistance elements 19 provided in the support part 15; and output electrodes 20 for taking out a resistance change of the piezoresistance element 19, insulating layers 31 are provided between the support part 15 and the weight part 13, and the support column part 14 and the fixing part 17, to make the support part 15 electrically independent, and electric insulating conditions are attained between the input electrode 18 and the output electrode 20, and between the support column part 14 and the fixing part 17, by the first substrate 11 and the second substrate 12. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an acceleration sensor that detects displacement of a weight portion that is displaced according to acceleration by a piezoresistive element and measures acceleration from the detection result, an electronic device having the acceleration sensor, and a method of manufacturing the acceleration sensor. is there.

Conventionally, as one of semiconductor MEMS (Micro Electro Mechanical System), a weight supporting part is used as a flexible supporting part. A mechanical quantity sensor that supports (hangs) and detects a displacement of the weight part and measures a mechanical quantity (for example, acceleration, angular velocity, etc.) from the detection result when some mechanical quantity is applied to the weight part from the outside. It has been known.
Various methods are known as methods for measuring various displacements such as the vibration direction and size of the weight portion. For example, the resistance change of the piezoresistive element provided on the support portion that supports the weight portion ( 2. Description of the Related Art A piezoresistive detection type mechanical quantity sensor that measures a mechanical quantity by detecting a mechanical quantity acting on a weight portion) is known.

As one of the mechanical quantity sensors using the piezoresistive element, for example, as shown in FIG. 36, a mechanics in which a piezoresistive element 53 is provided in each of a plurality of support parts 52 that support a weight part 51. A quantity sensor 50 is known (see, for example, Patent Document 1).
However, since the mechanical quantity sensor 50 is simply provided with the piezoresistive elements 53 in the respective support portions 52, the piezoresistive elements 53 are not separated from each other. Therefore, crosstalk due to leakage current (leakage current) occurs between the piezoresistive elements 53, which adversely affects other piezoresistive elements 53. For example, the piezoresistive element 53 that has not detected the displacement of the weight portion 51 may malfunction if it detects the displacement due to the influence of a leakage current. Therefore, it is difficult to accurately measure the displacement of the weight portion 51, and it is difficult to accurately measure a mechanical quantity (for example, acceleration).

Therefore, a mechanical quantity sensor is known in which a piezoresistive element is formed by injecting a p-type impurity at a high concentration into an n-type silicon substrate in order to eliminate the above-described leakage current as much as possible (for example, Patent Document 2 and 3).
In this mechanical quantity sensor, since the piezoresistive element and the silicon substrate are in a pn junction state, it becomes like a diode and prevents leakage current from the piezoresistive element to the silicon substrate. Thereby, the piezoresistive elements are separated from each other.
It is also known that a p-type impurity layer is further formed on a silicon substrate so as to surround the periphery of the piezoresistive element, thereby preventing leakage current and ensuring element isolation.

Further, as one of mechanical quantity sensors in which leakage current is minimized, a mechanical quantity sensor is known in which element isolation is achieved by mechanically insulating each piezoresistive element (for example, a patent) References 4 and 5).
That is, as shown in FIGS. 37 and 38, the mechanical quantity sensor 60 includes an insulator thin film 63 formed on the upper surface of each of the plurality of support portions 62 that support the weight portion 61, and the insulator thin film 63 on the upper surface. Further, a piezoresistive element 64 is formed by forming a semiconductor thin film. By this insulating thin film 63, each piezoresistive element 64 is completely electrically insulated, and the influence of the leakage current can be eliminated.
JP 2004-226085 A JP-A-8-162645 JP-A-9-203747 JP-A-6-296032 JP 2003-98025 A

However, the above-described conventional element isolation (leakage current prevention) method still has the following problems.
That is, in the methods described in Patent Documents 2 and 3, when the mechanical quantity sensor is exposed to a high temperature (for example, 100 ° C. or higher) state, or when light or electromagnetic waves are incident, the electric charge is generated on the silicon substrate. When excited, a leakage current occurs, resulting in incomplete element isolation.
Further, it is necessary to always select an n-type substrate, which is limited in the design stage. In addition, it is necessary to implant p-type impurities to form the piezoresistive element, and it is necessary to implant n-type impurities to form the electrode extraction portion. As a result, two stages of impurity implantation steps are required, resulting in a complicated manufacturing process.

In addition, in the mechanical quantity sensor 60 described in Patent Documents 4 and 5, etc., each piezoresistive element 64 can be separated, but the insulator thin film 63 is placed on one side on the flexible support portion 62. Since the film is formed, there is a disadvantage that the support portion 62 is deformed by the internal stress of the insulator thin film 63.
For example, as shown in FIG. 39, when the support part 62 is deformed in the longitudinal direction of the support part 62, the weight part 61 supported by the support part 62 comes into contact with the outer wall 65 of the mechanical quantity sensor. There is a possibility that problems such as changes in the vibration characteristics and disturbance of vibrations may occur.
In addition, as shown in FIG. 40, when the support portion 62 is deformed in its own short direction, the spring constant of the support portion 62 is similarly changed to change a predetermined vibration characteristic or prevent the vibration. There was a fear. As described above, there is a fear that the mechanical quantity cannot be accurately measured due to the deformation of the support portion 62.
Further, since it is necessary to form and pattern the insulator thin film 63 and the piezoresistive element 64 separately, there is a disadvantage that the process becomes complicated. Furthermore, in order to measure the resistance change of each piezoresistive element 64, each piezoresistive element 64 must be provided with at least two or more electrodes (input and output) 65, as shown in FIG. It was difficult to reduce the size.

  The present invention has been made in consideration of such circumstances, and its purpose is to completely leak the piezoresistive elements by mechanically isolating each piezoresistive element without affecting the support part that supports the weight part. An acceleration sensor capable of preventing an electric current, an electronic device having the acceleration sensor, and a method of manufacturing the acceleration sensor are provided.

The present invention provides the following means in order to solve the above problems.
The acceleration sensor of the present invention includes a first substrate and a second substrate that are arranged in parallel with each other at a predetermined interval, and a state in which the predetermined interval is provided with respect to the first substrate and the second substrate. An annular weight portion made of a semiconductor material sandwiched between the two substrates, and a semiconductor material provided at substantially the center of the weight portion and sandwiched between the first substrate and the second substrate. The columnar column part and the one end side are fixed with the column part interposed therebetween, and the other end side extends in a direction parallel to the surfaces of the first substrate and the second substrate, Sandwiched between a pair of support parts made of a semiconductor material that supports the weight part in a suspended state between the one end side and the other end side, the first substrate and the second substrate, A fixing portion made of a semiconductor material for fixing the other end side of the pair of support portions; and the support portion on the first substrate. Provided in an electrically connected state, an input electrode capable of applying a predetermined voltage to the support column, and provided on the surfaces of the pair of support parts, respectively, and an electric resistance depending on the stress acting on the support parts A piezoresistive element that changes, and an output electrode that is provided in a state of being electrically connected to the fixed portion on the first substrate, and that takes out a resistance change of the piezoresistive element through the fixed portion, An insulating layer that electrically separates the support portion is provided between the support portion and the weight portion, as well as the support portion and the fixed portion, and the first substrate and the second substrate are The input electrode and the output electrode, and the support column and the fixed part are electrically insulated.

In the acceleration sensor according to the present invention, first, a predetermined voltage is applied to the column through the input electrode. By this voltage application, the current supplied to the column portion reaches each output electrode through a pair of support portions and fixing portions on which the piezoresistive elements are formed. By detecting this current through the output electrode, the resistance value of each piezoresistive element can be monitored. That is, the input electrode is a common input electrode (common electrode). In addition, since the support | pillar part, a pair of support part, and the fixing | fixed part are each formed from the semiconductor material (for example, silicon),
A current flows reliably from the input electrode to the output electrode.

  Here, since the weight portion is suspended and supported by the pair of support portions with a predetermined distance from the first substrate and the second substrate, when the acceleration is applied, the first weight portion is supported. Displacement is made according to the magnitude and direction of the acceleration without contacting the second substrate and the second substrate. Then, the pair of support portions are deformed by bending or twisting (twisting around the axis of the pair of support portions) in accordance with the displacement of the weight portion. At this time, the piezoresistive element is similarly deformed along with the deformation of the pair of support portions. When the piezoresistive element is deformed, the resistance value monitored by each output electrode changes, so that the acceleration acting on the weight portion can be measured.

In particular, since an insulating layer is formed between the support portion and the weight portion, the current flowing through each piezoresistive element does not flow to the other piezoresistive elements via the weight portion. In addition, an insulating layer is similarly formed on the support column and the fixing unit, and the first substrate and the second substrate are electrically connected between the input electrode and the output electrode and between the support column and the fixing unit. Therefore, the current flowing through each piezoresistive element does not flow from the support post and the fixed part to the other piezoresistive elements through the first substrate and the second substrate.
That is, each piezoresistive element is electrically insulated at a place other than the input electrode and the output electrode. Therefore, each piezoresistive element can be mechanically completely separated, and leakage current (leakage current) to other piezoresistive elements can be prevented. Therefore, acceleration can be measured with high accuracy.

Further, the pair of support portions simply supports the weight portion in a suspended state between the one end side and the other end side, and the entire upper and lower surfaces of the pair of support portions are insulated as in the conventional case. There is no need to form a film. Therefore, unlike the conventional case, deformation such as bending of the support portion due to internal stress of the insulating film does not occur. Therefore, vibration characteristics can be ensured for the pair of support portions as designed, and acceleration can be measured with high accuracy.
In addition, since the weight portion is formed in an annular shape with the column portion as a substantial center, when the acceleration is applied, the moment can be gained and the displacement with respect to the input can be increased. Therefore, sensitivity can be improved.
Furthermore, since the input electrode which contacted the support | pillar part distribute | arranged to the approximate center of the weight part can be used as a common electrode, the number of electrodes can be decreased compared with the past. Therefore, size reduction can be achieved.

  The acceleration sensor manufacturing method according to the present invention includes an SOI substrate formed by sandwiching a silicon oxide film between a first silicon layer and a second silicon layer, the SOI substrate as a first substrate and a second substrate. A method of manufacturing an acceleration sensor bonded to an SOI substrate in a state of being sandwiched from both sides with a substrate, wherein a recess is formed in the first silicon layer, and an upper portion of a columnar column portion, One end side is fixed in a state of being sandwiched between the upper portions of a pair of support portions, the other end side extending in a direction parallel to the surfaces of the first substrate and the second substrate, and the pair of supports A recess forming step for forming the upper portion of the fixing portion for fixing the other end of the portion, and after the recess forming step, an impurity is implanted into the surface of the first silicon layer, and the support is formed on the surface of the support portion. Piezoelectric resistance changes according to the stress acting on the part An impurity implantation step for forming a resistance element, and after the impurity implantation step, a through hole is formed at a predetermined position of the first substrate, and the through hole is positioned on the upper surface of the support column and the fixing unit, respectively. A first bonding step for bonding the first substrate and the first silicon layer, and after the first bonding step, the second silicon layer is processed to form the support column and the pair of support portions. The pair of support portions are supported in a state of being suspended by the pair of support portions between one end side and the other end side of the pair of support portions, and at a predetermined interval with respect to the first substrate and the second substrate. A process step of forming a weight part formed in an annular shape in a state of being open, a removal process of removing the silicon oxide film exposed on the back side of the pair of support parts after the process process, After the removing step, the second substrate is bonded to the second silicon layer. After the bonding step and the second bonding step, a conductive thin film is formed or a conductive material is injected into each of the through holes, and a predetermined voltage can be applied to the column by being electrically connected to the column. An electrode forming step of forming an input electrode and an output electrode that is electrically connected to the fixed portion and takes out a resistance change of the piezoresistive element, and the first substrate and the second substrate include The input electrode and the output electrode, and the support column and the fixed part are electrically insulated.

  In the method of manufacturing the acceleration sensor according to the present invention, first, the recess is etched in the first silicon layer of the SOI substrate by the recess forming step, so that the upper part of the support part, the upper part of the pair of support parts, and the fixing part are formed. Each upper part is formed. Next, in the impurity implantation step, impurities are implanted into the surface of the first silicon layer by, for example, ion implantation or impurity diffusion to form a piezoresistive element that is a high concentration impurity layer. Next, a through hole is formed at a predetermined position of the first substrate by etching, sandblasting, or the like, and the first substrate and the first silicon layer are formed so that the through hole is located on the upper surface of the support column and the fixing unit. A first joining step for joining is performed.

Next, a processing step is performed in which the second silicon layer is processed by etching or the like to form a column portion, a fixed portion, a pair of support portions, and a weight portion. By this processing step, a columnar column part, a weight part formed in an annular shape with the column part as a center, and one end side of the column part are fixed to the surface of the first substrate and the second substrate. A pair of support portions that are supported in a state in which the other end side extends in the parallel direction and the weight portion is suspended between the one end side and the other end side, and a fixing portion that fixes the other end side of the pair of support portions, Can be formed respectively.
At this time, since the silicon oxide film, which is an insulating layer, is sandwiched between the second silicon layer and the first silicon layer, the pillar portion and the fixing portion have the silicon oxide film, which is an insulating layer, inside. It will be in the state of having. Similarly, a silicon oxide film that is an insulating layer is sandwiched between the pair of support portions and the weight portion.

Next, a removal step is performed to remove the silicon oxide film exposed on the back surfaces of the pair of support portions. As a result, the pair of support portions are formed only from the first silicon layer in a range excluding the region supporting the weight portion.
Next, the second substrate is bonded to the second silicon layer by the second bonding step. As a result, the weight portion formed in an annular shape is supported by the pair of support portions at a predetermined interval from the first substrate and the second substrate.
Next, a conductive thin film is formed or a conductive material is injected into each of the through holes formed in the first substrate, an input electrode capable of applying a predetermined voltage to the support column, and each piezoresistive element via the fixing unit. An electrode forming step for forming output electrodes for taking out resistance changes is performed.
By sequentially performing the above-described steps, an acceleration sensor can be manufactured using the first substrate, the second substrate, and the SOI substrate.
Note that the first substrate and the second substrate are electrically insulated between the input electrode and the output electrode, and between the column portion and the fixed portion.

  In the acceleration sensor manufactured in this way, first, a predetermined voltage is applied to the column through the input electrode, so that the column and the piezoresistive element are formed on the pair of support and fixing unit. A current can be passed through each output electrode. By detecting this current, the resistance value of each piezoresistive element can be monitored. That is, the input electrode is a common input electrode (common electrode). In addition, since the support | pillar part, a pair of support part, and the fixing | fixed part are each formed from the 1st silicon layer which is a semiconductor material, an electric current flows reliably from an input electrode to an output electrode.

  Here, the weight portion is displaced according to the magnitude and direction of the acceleration without contacting the first substrate and the second substrate when the acceleration is applied. Then, the pair of support portions are deformed by bending or twisting (twisting around the axis of the pair of support portions) in accordance with the displacement of the weight portion. Deform. When this piezoresistive element is deformed, the resistance value monitored by each output electrode changes, so that the acceleration acting on the weight portion can be measured.

In particular, since a silicon oxide film, which is an insulating layer, is formed between the support portion and the weight portion, the current flowing through each piezoresistive element does not flow to other piezoresistive elements via the weight portion. .
Similarly, a silicon oxide film, which is an insulating layer, is also formed on the support column and the fixing unit, and the first substrate and the second substrate are provided between the input electrode and the output electrode and between the support column and the fixing unit. Since the circuit board is electrically insulated, the current flowing through each piezoresistive element flows from the column and the fixed part to the other piezoresistive element through the first board and the second board. There is no.
That is, each piezoresistive element is electrically insulated at a place other than the input electrode and the output electrode. Therefore, each piezoresistive element can be mechanically completely separated, and leakage current (leakage current) to other piezoresistive elements can be prevented. Therefore, acceleration can be measured with high accuracy.

Further, the pair of support portions simply supports the weight portion in a suspended state between the one end side and the other end side, and the entire upper and lower surfaces of the pair of support portions are insulated as in the conventional case. There is no need to form a film. Therefore, unlike the conventional case, deformation such as bending of the support portion due to internal stress of the insulating film does not occur. Therefore, vibration characteristics can be ensured for the pair of support portions as designed, and acceleration can be measured with high accuracy.
In addition, since the weight portion is formed in an annular shape with the column portion as a substantial center, when the acceleration is applied, the moment can be gained and the displacement with respect to the input can be increased. Therefore, the sensitivity can be improved.
Furthermore, since the input electrode which contacted the support | pillar part distribute | arranged to the approximate center of the weight part can be used as a common electrode, the number of electrodes can be decreased compared with the past. Therefore, size reduction can be achieved.

  The acceleration sensor manufacturing method of the present invention includes an SOI substrate formed by sandwiching a silicon oxide film between a first silicon layer and a second silicon layer, and the SOI substrate as a first substrate and a second substrate. And manufacturing the acceleration sensor bonded to the SOI substrate with both sides sandwiched from both sides, wherein the second silicon layer is processed to sandwich the lower part of the columnar column part and the column part therebetween. In this state, one end side is fixed, and the other end side extends in a direction parallel to the surfaces of the first substrate and the second substrate. A lower portion of the fixing portion that fixes the end side, and is supported in a state of being suspended by the pair of support portions between one end side and the other end side of the pair of support portions, and the first substrate and the first A weight portion formed in an annular shape with a predetermined distance from the substrate 2 Each forming process, a removing process for removing the silicon oxide film exposed on the back side of the pair of support portions after the processing process, and a second silicon layer after the removing process A first bonding step for bonding the second substrate, and after the first bonding step, a recess is formed in the first silicon layer, and the column portion, the pair of support portions, and the fixing portion are A recess forming step to be formed, and after the recess forming step, impurities are implanted into the entire surface of the first silicon layer to form an impurity layer on the upper surface of the support column and the upper surface of the fixed portion, and the pair An impurity implantation step for forming a piezoresistive element whose electrical resistance changes according to the stress acting on the support portion on the surface of the support portion; and after the impurity implantation step, a through-hole is formed at a predetermined position of the first substrate. And the through-holes are A second bonding step of bonding the first substrate and the first silicon layer so as to be positioned on the upper surfaces of the support column and the fixing portion; and after the second bonding step, a conductive thin film is respectively applied to the through hole. In a state in which film formation or conductive material is injected and provided in an electrically connected state to the column part, an input electrode capable of applying a predetermined voltage to the column part and an electrically connected state to the fixed part And an electrode forming step for forming external electrodes for taking out resistance changes of the piezoresistive elements, respectively, wherein the first substrate and the second substrate are between the input electrode and the output electrode, In addition, the column portion and the fixed portion are electrically insulated from each other.

In the method of manufacturing the acceleration sensor according to the present invention, first, the second silicon layer of the SOI substrate is etched by a processing step, so that the lower part of the support part, the lower part of the pair of support parts, the lower part of the fixing part, the support part, One end side is fixed to the support column with the portion interposed therebetween, and the other end side extends in a direction parallel to the surfaces of the first substrate and the second substrate, and between the one end side and the other end side. The annular weight portions that are supported in a state where the weight portions are suspended are formed respectively.
At this time, since the silicon oxide film, which is an insulating layer, is sandwiched between the second silicon layer and the first silicon layer, the pillar portion and the fixing portion have the silicon oxide film, which is an insulating layer, inside. It will be in the state of having. Similarly, a silicon oxide film that is an insulating layer is sandwiched between the pair of support portions and the weight portion.

Next, a removal step is performed to remove the silicon oxide film exposed on the back surfaces of the pair of support portions. As a result, the pair of support portions are formed only from the first silicon layer in a range excluding the region supporting the weight portion.
Next, the second substrate is bonded to the second silicon layer by the first bonding step. As a result, the annularly formed weight portion is supported by the pair of support portions at a predetermined interval from the second substrate.

Next, the support part, the pair of support parts, and the fixing part can be formed by etching the recesses in the first silicon layer in the recess forming process.
Next, in the impurity implantation step, impurities are implanted into the surface of the first silicon layer by, for example, ion implantation or impurity diffusion to form a piezoresistive element that is a high concentration impurity layer.
Next, a through hole is formed at a predetermined position of the first substrate by etching, sandblasting, or the like, and the first substrate and the first silicon layer are formed so that the through hole is located on the upper surface of the support column and the fixing unit. A second joining step for joining is performed. As a result, the weight portion formed in an annular shape is supported by the pair of support portions at a predetermined interval from the first substrate and the second substrate.

Next, a conductive thin film is formed or a conductive material is injected into each of the through-holes formed in the first substrate, and an input electrode capable of applying a predetermined voltage to the column portion, and each piezoresistor via the fixing portion An electrode forming process is performed for forming output electrodes for taking out the resistance changes of the elements.
By sequentially performing the above-described steps, an acceleration sensor can be manufactured using the first substrate, the second substrate, and the SOI substrate.
Note that the first substrate and the second substrate are electrically insulated between the input electrode and the output electrode, and between the column portion and the fixed portion.

  The acceleration sensor manufactured in this way can exhibit the same effects as the acceleration sensor of the present invention described above.

  Further, the acceleration sensor of the present invention is the acceleration sensor of the present invention, wherein the plurality of pairs of support portions are provided at a predetermined angle with the support column as a center, and the piezoresistive element and the output electrode are the pair of support electrodes. It is provided according to the number of support parts.

  Further, the acceleration sensor manufacturing method of the present invention is the acceleration sensor manufacturing method of the present invention described above, wherein the pair of support portions are centered on the support column portions at a predetermined angle when the recess forming step and the processing step are performed. A plurality of each is formed, and when performing the impurity implantation step, the first bonding step or the second bonding step, and the electrode forming step, the piezoresistive element and the output electrode are supported by the pair of supports. It is formed according to the number of parts.

  In the acceleration sensor and the method of manufacturing the acceleration sensor according to the present invention, the pair of support portions are provided at a position rotated, for example, 90 degrees around the support column. That is, the pair of support portions are provided so as to be parallel to the surfaces of the first substrate and the second substrate and to face the XY directions orthogonal to each other. Each support portion is provided with a piezoresistive element and an output electrode. Therefore, the acceleration around the two axes of XY can be measured with high accuracy.

  The acceleration sensor according to the present invention is the acceleration sensor according to the present invention, wherein the fixed portion is sandwiched between the first substrate and the second substrate, and the other end side of the pair of support portions. And an outer frame portion sandwiched between the first substrate and the second substrate and surrounding the outer strut portion from the periphery. Is.

  The acceleration sensor manufacturing method according to the present invention is the acceleration sensor manufacturing method according to any one of the above-described inventions, wherein the other end side of the pair of support portions when performing the recess forming step and the processing step. Are formed by forming a columnar outer supporting column portion that independently fixes the outer supporting column portion and an outer frame portion that surrounds the outer supporting column portion from the periphery.

  In the acceleration sensor and the method for manufacturing the acceleration sensor according to the present invention, the other end sides of the pair of support portions are fixed to the columnar outer support portions that are independently provided, so that each piezoresistive element is more reliably connected. The elements can be separated, and the occurrence of leakage current to other piezoresistive elements can be reliably prevented. Therefore, the acceleration can be measured with higher accuracy. Further, since the periphery of the outer support column is surrounded by the outer frame portion, the inside can be hermetically sealed, and the whole becomes stronger.

  The acceleration sensor according to the present invention is characterized in that, in the acceleration sensor according to the present invention, the weight portion is formed up to the vicinity of the outer frame portion.

  The acceleration sensor manufacturing method of the present invention is characterized in that, in the acceleration sensor manufacturing method of the present invention, the weight portion is formed to the vicinity of the outer frame portion in the processing step. .

  In the acceleration sensor and the method for manufacturing the acceleration sensor according to the present invention, the weight portion is formed to the vicinity of the outer frame portion, so that the weight of the weight portion can be increased as much as possible. Thereby, a moment can be enlarged and a sensitivity can be improved more.

  The acceleration sensor according to the present invention is the acceleration sensor according to any one of the above-described inventions, wherein an impurity layer is formed in the support portion and the fixed portion in a range in contact with the input electrode and the output electrode. It is characterized by being.

  The acceleration sensor manufacturing method of the present invention is the acceleration sensor manufacturing method according to any one of the above-described present invention, wherein an impurity layer is formed on the upper surface of the support column and the upper surface of the fixing unit in the impurity implantation step. It is characterized by forming.

  In the acceleration sensor and the acceleration sensor manufacturing method according to the present invention, since the impurity layer is formed on the upper surfaces of the support column and the fixed portion, the withstand voltage can be increased. Therefore, it is easy to reliably apply a predetermined voltage from the input electrode, and it is possible to reliably detect a change in resistance of the piezoresistive element.

  The acceleration sensor according to the present invention is the acceleration sensor according to the present invention, further comprising a metal film that electrically connects the impurity layer and the piezoresistive element.

  The acceleration sensor manufacturing method according to the present invention is the acceleration sensor manufacturing method according to any one of the above-described inventions, wherein the impurity layer and the piezoresistive element are electrically connected by a metal film during the impurity implantation step. It is characterized by making it connect.

  In the acceleration sensor and the acceleration sensor manufacturing method according to the present invention, since the impurity layer and the piezoresistive element are electrically connected by the metal layer, the resistance value is reduced, and the current easily flows from the input electrode to the output electrode. . Thereby, while improving S / N ratio, power consumption can be suppressed and performance improvement can be aimed at.

  The acceleration sensor according to the present invention is the acceleration sensor according to any one of the above-described inventions, wherein the piezoresistive element is provided over the entire length of the support portion with a width smaller than the lateral width of the support portion. It is a feature.

  The acceleration sensor manufacturing method according to the present invention is the acceleration sensor manufacturing method according to any one of the above-described inventions, wherein the piezoresistive element has a width smaller than a lateral width of the support portion in the impurity implantation step. It forms over the full length of a support part, It is characterized by the above-mentioned.

  In the acceleration sensor and the acceleration sensor manufacturing method according to the present invention, since the piezoresistive element is formed with a width smaller than the lateral width of the support portion, it is possible to reduce a resistance change due to a torsional stress and reduce an erroneous output as much as possible. The acceleration in the direction in which the support portion bends can be measured with higher accuracy.

  Moreover, the acceleration sensor according to the present invention is the acceleration sensor according to any one of the above-described present invention, wherein the piezoresistive element is divided into two at a region where the support portion and the weight portion intersect, The support portion and the weight portion are electrically connected to each other through a metal film provided on the surface of the support portion in a range where the support portion and the weight portion intersect.

  The acceleration sensor manufacturing method of the present invention is the acceleration sensor manufacturing method according to any one of the above-described inventions, wherein the piezoresistive element is connected to the support portion and the weight portion during the impurity implantation step. It is formed so that it bisects with the intersecting region as the boundary, and a metal film is formed on the upper surface of the support part in the range where the support part and the weight part intersect, and the piezoresistive element divided into two by the metal film is electrically connected It is characterized by doing.

  In the acceleration sensor and the method of manufacturing the acceleration sensor according to the present invention, the piezoresistive element is divided into two regions with the support portion and the weight portion intersecting, that is, the region supporting the weight portion. Piezoresistive elements divided in half by a metal film formed only on the top are electrically connected. That is, the weight portion is supported, and the portion that does not contribute to displacement detection without generating stress is bypassed by the metal film, so that the electrical resistance can be further reduced and the sensitivity of the piezoresistive element can be further improved. it can.

  Moreover, the acceleration sensor of the present invention is the acceleration sensor according to any one of the above-described present invention, wherein the first substrate and the second substrate are glass substrates.

  Moreover, in the manufacturing method of the acceleration sensor of this invention, in the manufacturing method of the acceleration sensor in any one of the said invention, the said 1st board | substrate and the said 2nd board | substrate are glass substrates, It is characterized by the above-mentioned. To do.

  In the acceleration sensor and the acceleration sensor manufacturing method according to the present invention, since the first substrate and the second substrate are glass substrates, between the input electrode and the output electrode, and between the support column and the fixing unit. Can be completely insulated. Therefore, the element separation of the piezoresistive element can be further ensured.

  An electronic apparatus according to the present invention includes the acceleration sensor according to any one of the present inventions.

  In the electronic apparatus according to the present invention, acceleration can be measured with high accuracy, and the acceleration sensor with reduced size and improved sensitivity is provided, so that downsizing and improved performance can be achieved.

According to the acceleration sensor and the method of manufacturing the acceleration sensor according to the present invention, each piezoresistive element is electrically insulated at a place other than the input electrode and the output electrode. Therefore, it is possible to completely isolate the elements, to prevent leakage current (leakage current) to other piezoresistive elements, and to measure acceleration with high accuracy.
In addition, since it is not necessary to form a conventional insulating film on the entire upper and lower surfaces of the pair of support portions, the support portion is not deformed such as being bent due to the internal stress of the insulating film as in the conventional case. Therefore, the pair of support portions can have vibration characteristics as designed, and the acceleration can be measured with high accuracy. Further, since the weight portion is formed in an annular shape with the support column portion as the center, the moment can be increased, the displacement with respect to the input can be increased, and the sensitivity can be improved. Furthermore, since the input electrode can be used as a common electrode, the number of electrodes can be reduced as compared with the conventional case, and the size can be reduced.
Moreover, according to the electronic device which concerns on this invention, size reduction and the improvement of a performance can be aimed at.

Hereinafter, an embodiment of an acceleration sensor, an electronic apparatus, and a method for manufacturing the acceleration sensor according to the present invention will be described with reference to FIGS.
In the present embodiment, the electronic device will be described below as an electronic device having a hard disk capable of writing and reading various information.
That is, the electronic device 1 includes a drive unit 2 and a sensor unit 3 having an acceleration sensor 10 as shown in FIG. The drive unit 2 includes a magnetic head 4 that records and reproduces various signals on a hard disk (not shown), and a head drive circuit 5 that drives the magnetic head 4 based on the acceleration sent from the sensor unit 3. That is, the head drive circuit 5 protects the hard disk by separating the magnetic head 4 from the hard disk and stopping writing and reading when some acceleration (for example, acceleration due to dropping) is applied to the electronic device 1. It has become. That is, it operates as a hard disk protection mechanism.

  The sensor unit 3 includes an acceleration sensor 10, a CV conversion circuit 6 that converts a capacitance according to the acceleration detected by the acceleration sensor 10 into a voltage, and an acceleration calculation that calculates acceleration from the converted voltage. Circuit 7. The acceleration calculation circuit 7 outputs the calculated acceleration to the head drive circuit 5.

In the present embodiment, the acceleration sensor 10 includes a BOX layer 31 (Buried Oxide) (for example, a thickness of 1 μm), which is a silicon oxide film, and a silicon active layer 32 (first silicon layer) (for example, a thickness). 10 μm) and a silicon support layer 33 (second silicon layer) (for example, a thickness of 300 μm), an SOI substrate 30 formed between the first glass substrate (first substrate) 11 and the SOI substrate 30. In the following description, it is assumed that the glass substrate (second substrate) 12 is bonded to the SOI substrate 30 while being sandwiched from both sides.
In addition, when a pair of support portions to be described later is provided in two (two axes) so as to extend toward the XY axes that are parallel to the surfaces of the first glass substrate 11 and the second glass substrate 12, respectively. Will be described as an example. In the present embodiment, the pair of support portions arranged along the X-axis direction will be described as the X-axis support portion 15, and the pair of support portions arranged along the Y-axis direction will be described as the Y-axis support portion 16. .

  That is, as shown in FIGS. 2 to 5, the acceleration sensor 10 includes a first glass substrate 11 and a second glass substrate 12 arranged in parallel with each other at a predetermined interval, and the first glass substrate 11. And an annular weight portion 13 composed of an SOI substrate (semiconductor material) 30 sandwiched between the glass substrates 11 and 12 with a predetermined distance from the second glass substrate 12, and the weight portion 13 A columnar column 14 formed of an SOI substrate 30 provided substantially at the center and sandwiched between the first glass substrate 11 and the second glass substrate 12, and one end with the column 14 interposed therebetween While the sides 15a and 16a are fixed, the other end sides 15b and 16b extend in the parallel direction (XY axis) to the surfaces of the first glass substrate 11 and the second glass substrate 12, and the one end side 15a and Between 16a and other end side 15b, 16b It is sandwiched between the X-axis support part 15 and the Y-axis support part 16 made of the SOI substrate 30 that supports the weight part 13 in a suspended state, and the first glass substrate 11 and the second glass substrate 12. The support part 15, the other end side 15 b of the support part 16, the fixing part 17 made of the SOI substrate 30 for fixing the 16 b, and the first glass substrate 11 are provided in a state of being electrically connected to the support pillar part 14. An input electrode 18 to which a predetermined voltage can be applied, a piezoresistive element 19 provided on the surface of each of the support portions 15 and 16 and having an electric resistance that changes in accordance with the stress acting on the support portions 15 and 16; One glass substrate 11 is provided in a state of being electrically connected to the fixing portion 17, and includes an output electrode 20 that takes out a resistance change of the piezoresistive element 19 through the fixing portion 17.

The weight portion 13 is formed in a square shape in cross section, and has a two-layer structure in which the silicon support layer 33 and the BOX layer 31 are overlapped.
The support column 14 is provided at the center of the weight 13 in a state of having a regular quadrangular cross section (for example, one side of 100 μm or more). The silicon support layer 33, the BOX layer 31, and the silicon active layer 32 are provided. It has a three-layer structure with Further, an impurity layer 35 is formed on the entire upper surface (in the range in contact with the input electrode 18) on the upper surface of the support column 14, that is, the upper surface of the silicon support layer 33.
Further, one end sides 15 a and 16 a of the support portions 15 and 16 are fixed to the silicon active layer 32. As a result, the current that has flowed to the support column 14 via the input electrode 18 does not flow to the silicon support layer 33 side by the BOX layer 31 that is an insulating layer, but reliably flows to the support portions 15 and 16. That is, the one end sides 15 a and 16 a of the support portions 15 and 16 are in an electrically independent state at a place other than being in contact with the input electrode 18.

  The X-axis support parts 15 and 16 and the Y-axis support parts 15 and 16 are in a positional relationship rotated by 90 degrees about the column part 14, for example, the width is 50 μm, the thickness is 10 μm, and the length is 500 μm. The silicon active layer 32 is formed to have a size of Further, the weight portion 13 is supported via the BOX layer 31 at approximately the middle between the one end sides 15a and 16a and the other end sides 15b and 16b. That is, the support portions 15 and 16 and the weight portion 13 are electrically insulated by the BOX layer 31.

The fixing portion 17 is sandwiched between the first glass substrate 11 and the second glass substrate 12 and is columnar 4 for fixing the other end sides 15b and 16b of the support portions 15 and 16 independently. Two outer support portions 36 and a frame portion (outer frame portion) 37 sandwiched between the first glass substrate 11 and the second glass substrate 12 and surrounding the four outer support portions 36 from the periphery. Yes.
The outer support column 36 is formed in a three-layer structure including a silicon support layer 33, a BOX layer 31 and a silicon active layer 32 in the same manner as the support column 14, and has a quadrangular cross section. , 16 are fixed at the other ends 15b, 16b. Further, an impurity layer 35 is formed on the entire surface (in a range in contact with the output electrode 20) on the upper surface of the outer support column 36, that is, the upper surface of the silicon active layer 32. As a result, the current flowing from the input electrode 18 to the support column 14 reliably flows toward the output electrode 20 without flowing to the silicon support layer 33 side by the BOX layer 31 that is an insulating layer. In other words, the other end sides 15 b and 16 b of the support portions 15 and 16 are in an electrically independent state at a place other than being in contact with the output electrode 20.
In this way, each support portion 15, 16 has both ends on the column portion 14 and the four outer column portions 36 provided in an island shape between the first glass substrate 11 and the second glass substrate 12, respectively. Is fixed, and is electrically independent in a region other than being in contact with the input electrode 18 and the output electrode 20.

  Similarly, the frame portion 37 has a three-layer structure including a silicon support layer 33, a BOX layer 31, and a silicon active layer 32, and has a square cross section. The piezoresistive element 19 is formed from a high-concentration impurity layer, and is provided over the entire upper surface of each of the support portions 15 and 16. The surface resistivity of the piezoresistive element 19 is preferably 5 Ω / cm or less, which is lower than that of silicon, for example.

The first glass substrate 11 is formed with through holes 38 having a tapered cross section at positions facing the upper surface of the support column 14 and the upper surfaces of the four outer support columns 36. Each through hole 38 is formed by forming a conductive thin film or injecting a conductive material, and is electrically connected to the impurity layer 35 formed on the upper surface of the support column 14 and the upper surface of the outer support column 36, respectively. The input electrode 18 and the output electrode 20 are provided.
Moreover, since the 1st glass substrate 11 and the 2nd glass substrate 12 are each an insulator, between the input electrode 18 and the output electrode 20, and the support | pillar part 14 and the fixing | fixed part 17, ie, the support | pillar part 14 The outer support 36 and the frame 37 are electrically insulated from each other.

Next, a method for manufacturing the acceleration sensor 10 configured as described above will be described below.
That is, in the method of manufacturing the acceleration sensor according to the present embodiment, the recesses 40 are formed in the silicon active layer 32 to form the recesses that form the upper part of the column part 14, the upper parts of the support parts 15 and 16, and the upper part of the fixing part 17. After the step and the recess forming step, impurities are implanted into the surface of the silicon active layer 32 to form the piezoresistive elements 19 on the surfaces of the support portions 15 and 16, respectively. An impurity implantation step for forming an impurity layer 35 on the upper surface of the first glass substrate, and after the impurity implantation step, a through hole 38 is formed at a predetermined position of the first glass substrate 11. A first bonding step for bonding the first glass substrate 11 and the silicon active layer 32 so as to be positioned on the upper surface of the outer support column 36, and after the first bonding step, the silicon support layer 33 is processed, Prop section 4. Processing step for forming the fixing portion 17, the support portions 15, 16 and the weight portion 13, respectively, and the removal for removing the BOX layer 31 exposed on the back side of the support portions 15, 16 after the processing step A second bonding step of bonding the second glass substrate 12 to the silicon support layer 33 after the step, and the removing step; and after the second step, a conductive thin film or a conductive material is formed in the through-hole 38, respectively. And an electrode forming step of forming the input electrode 18 and the output electrode 20 by injection.

Further, in the present embodiment, the X-axis support portion 15 and the Y-axis support portion 16 are formed so as to have a positional relationship rotated by 90 degrees around the support column portion 14 when performing the recess forming step and the processing step, When performing the impurity implantation step, the first bonding step, and the electrode formation step, the piezoresistive element 19 and the output electrode 20 are formed according to the number of support portions.
Moreover, in this embodiment, when performing a recessed part formation process and a process process, the four outer support | pillar parts 36 and the frame part 37 are formed, and the fixing | fixed part 17 is produced.
Each of these steps will be described in detail below.

  First, a photoresist film (not shown) serving as an etching mask on the silicon active layer 32 of the SOI substrate 30 shown in FIG. 6 is circularly patterned around the support portion 14 by the photoresist technique (the lengths of the support portions 15 and 16). Is patterned into a regular quadrilateral shape so that the width becomes. Then, as shown in FIG. 7, by using the photoresist film as a mask, reactive ion etching (RIE) or DRIE (Deep Reactive Ion Etching) is performed to select the unmasked silicon active layer 32. Are removed to form an annular recess 40.

At this time, the reaction rate and the like are set so that the depth of the concave portion 40 becomes a predetermined depth (for example, about several μm). The silicon active layer 32 may be removed by anisotropic etching (wet etching) using an alkaline etchant such as potassium hydroxide (KOH) or tetramethylammonium hydroxide (TMAH), not limited to the dry etching described above. .
Then, as shown in FIG. 7, the photoresist film used as the mask is removed. By this recess forming step, the upper portion of the support portion 14, the upper portions of the support portions 15 and 16, the upper portion of the outer support portion 36 and the frame portion 37 (fixed portion 17) can be formed in the silicon active layer 32. At this stage, the outer column part 36 and the frame part 37 are integrally formed.

Next, as shown in FIG. 8, impurities are implanted into the entire surface of the silicon active layer 32 by ion implantation, impurity diffusion, or the like, and the upper surface of the support column 14, the outer support column 36, and the frame unit 37 (fixed unit 17). The high-concentration impurity layer 35 (for example, the surface resistivity is several Ω / cm) is formed on the upper surface, and the piezoresistive element 19 composed of the high-concentration impurity layer 35 is formed on the entire upper surfaces of the support portions 15 and 16. An impurity formation step is performed.
Next, as shown in FIG. 9, a photoresist film (not shown) is patterned on the silicon active layer 32, and the silicon active layer 32 is etched using the photoresist film as a mask, so that the upper portion of the outer support portion 36 and the frame are formed. The upper part of the part 37 is divided and formed.

  Next, as shown in FIG. 10, a plurality of through-holes 38 in which the input electrode 18 and the output electrode 20 are formed at predetermined positions of the first glass substrate 11 are tapered, for example, by sandblasting or drying. It is formed by an etching method or a wet etching method. Then, as shown in FIG. 11, the first glass substrate 11 and the silicon active layer 32 are joined by anodic bonding so that each through hole 38 is located on the upper surface of the support column 14 and the upper surface of the outer support column 36, respectively. The first joining step is performed.

Next, as shown in FIG. 12, a photoresist and a film (not shown) are patterned on the silicon support layer 33, and the silicon support layer 33 is etched to a depth of, for example, several μm using the photoresist film as a mask. The recess 41 is formed. The concave portion 41 serves as a gap that separates the weight portion 13 and the second glass substrate 12 by a predetermined distance.
After the formation of the recess 41, as shown in FIG. 13, a photoresist film (not shown) is further patterned on the silicon support layer 33, and the silicon support layer 33 is etched using the photoresist film as a mask. 14, the above-described processing steps for forming the weight part 13, the support parts 15 and 16, the outer support part 36 and the frame part 37 are performed. At this stage, the BOX layer 31 is in a connected state.

Next, as shown in FIG. 14, the above-described removal step of removing the BOX layer 31 exposed from the silicon support layer 33 side is performed. That is, the BOX layer 31 exposed on the back surface side of each of the support parts 15 and 16 and the BOX layer 31 positioned between the outer column part 36 and the frame part 37 are removed. By performing this removal step, the support column part 14, the outer support column part 36, and the frame part 37 have a three-layer structure including a silicon active layer 32, a BOX layer 31 that is an insulating layer, and a silicon support layer 33. Between the weight portion 13 and the support portions 15 and 16, a BOX layer 31 that is an insulating layer is provided.
In the present embodiment, the BOX layer 31 remains on the entire upper surface of the weight portion 13, but the region not supported by the support portions 15, 16, that is, the support portions 15, 16 and the weight portion 13, The BOX layer 31 other than the region where the crosses may be removed.

After the removal step, as shown in FIG. 15, the second bonding step is performed in which the silicon support layer 33 and the second glass substrate 12 are bonded by anodic bonding. As a result, the weight portion 13 formed in an annular shape is supported by the support portions 15 and 16 with a predetermined distance from the first glass substrate 11 and the second glass substrate 12.
Next, the electrode formation for forming the input electrode 18 and the output electrode 20 by forming a conductor thin film or injecting a conductor material on at least the inner peripheral surface of the plurality of through holes 38 formed in the first glass substrate 11. Perform the process.
By performing each process mentioned above, the acceleration sensor 10 shown in FIG. 2 can be manufactured. In addition, since it manufactures using the 1st glass substrate 11 and the 2nd glass substrate 12, between the input electrode 18 and the output electrode 20, and between the support | pillar part 14 and the outer support | pillar part 36 is electrically insulated. It has become a state.

Next, the case where the acceleration sensor 10 configured as described above detects the acceleration at the time of dropping, stops writing and reading to the hard disk, and protects the hard disk will be described below.
First, a predetermined voltage is applied to the support column 14 via the input electrode 18, and the support electrode 15, 16, on which the piezoresistive element 19 is formed, and the input electrode 18 via the outer support column 36. A current is passed through the output electrode 20. Further, the resistance value of each piezoresistive element 19 is monitored by detecting this current. Here, the input electrode 18 is a common input electrode (common electrode).
In addition, since the support | pillar part 14 with which the input electrode 18 is contacting, the support parts 15 and 16, and the outer support | pillar part 36 with which the output electrode 20 is contacting are comprised of the silicon | silicone active layer 32, from the input electrode 18 which is a common electrode, A current flows to each output electrode 20 through each piezoresistive element 19.

Here, the weight portion 13 is supported by being suspended by the support portions 15 and 16 with a predetermined distance (gap) from the first glass substrate 11 and the second glass substrate 12. When the acceleration is applied, the first glass substrate 11 and the second glass substrate 12 are not brought into contact with each other and are displaced according to the magnitude and direction of the acceleration. As the weight portion 13 is displaced, the support portions 15 and 16 are bent or deformed by being twisted around the XY axes. At this time, as the support portions 15 and 16 are deformed, the piezoresistive element 19 is similarly deformed. When the piezoresistive element 19 is deformed, the resistance value monitored by each output electrode 20 changes, so that the acceleration acting on the weight portion 13 can be measured.
In particular, in this embodiment, since the X-axis support part 15 and the Y-axis support part 16 are provided, acceleration around two axes can be measured with high accuracy.

  The measured acceleration is sent to the head drive circuit 5 via the CV conversion circuit 6 and the acceleration calculation circuit 7. The head drive circuit 5 compares, for example, the sent acceleration with a predetermined value (threshold value), and if the comparison result shows that the value is equal to or greater than the threshold value, the head drive circuit 5 determines that the magnetic head 4 is falling. Separate from. Thereby, the hard disk can be protected.

In particular, in the acceleration sensor 10 of the present embodiment, since the BOX layer 31 that is an insulating layer is formed between the support portions 15 and 16 and the weight portion 13, the current flowing through each piezoresistive element 19 is the weight portion 13. It does not flow to the other piezoresistive elements 19 via.
Further, the BOX layer 31 is similarly formed on the support column 14 and the outer support column 36, and the first layer is formed between the input electrode 18 and the output electrode 20 and between the support column 14 and the outer support column 36. Since the glass substrate 11 and the second glass substrate 12 are electrically insulated, the current flowing through each piezoresistive element 19 passes through the first glass substrate 11 and the second glass substrate 12. It does not flow to other piezoresistive elements 19.
That is, each piezoresistive element 19 is electrically insulated at a place other than the input electrode 18 and the output electrode 20. Therefore, each piezoresistive element 19 can be mechanically and completely separated, and leakage current (leakage current) to other piezoresistive elements 19 can be prevented. Therefore, acceleration can be measured with high accuracy.

The support portions 15 and 16 merely support the weight portion 13 in a suspended state between the one end side 15a and 16a and the other end side 15b and 16b. Further, it is not necessary to form a conventional insulating film on the entire lower surface. Therefore, unlike the conventional case, the support portions 15 and 16 are deformed by bending due to the internal stress of the insulating film, so that the vibration characteristic such as the resonance Q value becomes small or the resonance point shifts hardly occurs. . Therefore, the vibration characteristics can be secured with the specifications of the support portions 15 and 16 as designed, and the acceleration can be measured with high sensitivity.
Further, since it is not necessary to provide a piezoresistive element on the insulating layer after forming an insulating layer on the upper and lower surfaces of the support portions 15 and 16 as in the prior art, the process can be shortened. . Further, the substrate and the implanted impurities can be adopted regardless of p-type and n-type, and the degree of design freedom can be increased.

In addition, since the weight portion 13 is formed in an annular shape with the column portion 14 as the center, when the acceleration is applied, a moment can be gained and the displacement with respect to the input can be increased. Therefore, the sensitivity can be further improved.
Furthermore, since the input electrode 18 that is in contact with the column portion 14 disposed at the center of the weight portion 13 can be used as a common electrode, the number of electrodes can be reduced as compared with the conventional case. Therefore, size reduction can be achieved.
For example, in a conventional biaxial acceleration sensor, it is necessary to provide at least two electrodes in four piezoresistive elements, and at least eight electrodes are required. On the other hand, in the acceleration sensor 10 of the present embodiment, each piezoresistive element 19 is connected to the input electrode 18 that is a common electrode, so that only five electrodes are required. Here, at least one side of the support column 14 and the four outer support columns 36 is required to have a size of 100 μm or more. In consideration of the surrounding clearance, it is necessary to secure an area of about 200 μm or more on one side. Considering these points, according to the acceleration sensor 10 of the present invention, a reduction in size of 1.2 × 10 ⁵ μm ² or more can be achieved.

  In addition, since the impurity layer 35 is formed on the upper surfaces of the support column 14 and the outer support column 36, the withstand voltage can be increased. Therefore, it is easy to apply a predetermined voltage from the input electrode 18 reliably, and the resistance change of the piezoresistive element 19 can be reliably detected.

  In addition, according to the electronic apparatus 1 of the present embodiment, as described above, the acceleration sensor 10 that can measure acceleration with high accuracy and has improved downsizing and sensitivity is similarly provided. In addition, the performance can be improved.

  The technical scope of the present invention is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the present invention.

For example, in the above embodiment, when the acceleration sensor 10 is manufactured, the first glass substrate 11 is bonded first from the silicon active layer 32 side. However, the present invention is not limited to this, and the second glass substrate 11 from the silicon support layer 33 side is used. The glass substrate 12 may be bonded first. A method for manufacturing the acceleration sensor 10 in this case will be described below.
That is, the acceleration sensor manufacturing method in this case is obtained by processing the silicon support layer 33 to form the lower part of the support part 14, the lower parts of the support parts 15 and 16, the fixing part 17, that is, the outer support part 36 and the frame part 37. Forming a lower portion of the weight portion 13 and a lower portion of the weight portion 13, a removal step of removing the BOX layer 31 exposed on the back side of each support portion 15 and 16 after the processing step, and after the removal step, A first bonding step for bonding the second glass substrate 12 to the silicon support layer 33, and after the first bonding step, a recess 40 is formed in the silicon active layer 32 to form the support column 14, each support unit 15, 16, the recessed portion forming step for forming the fixing portion 17, that is, the outer support column portion 36 and the frame portion 37, respectively, and after the recessed portion forming step, impurities are implanted into the surface of the silicon active layer 32, Piezoresistive element 1 on the surface And an impurity implantation step for forming an impurity layer 35 on the upper surface of the support column portion 14 and the upper surface of the outer support column portion 36, and after the impurity injection step, a through hole 38 is formed at a predetermined position of the first glass substrate 11. A second bonding step of bonding the first glass substrate 11 and the silicon active layer 32 so that the through-holes 38 are positioned on the upper surface of the support column 14 and the upper surface of the outer support column 36, respectively, After the second bonding step, there is provided an electrode forming step of forming the input electrode 18 and the output electrode 20 by forming a conductive thin film or injecting a conductive material into the through-holes 38, respectively.
Each of these steps will be described in detail below with reference to FIGS.

First, a photoresist and a film (not shown) are patterned on the silicon support layer 33 of the SOI substrate 30 shown in FIG. 16, and the silicon support layer 33 is etched to a depth of, for example, several μm using the photoresist film as a mask. Then, the recess 41 is formed as shown in FIG. The concave portion 41 serves as a gap that separates the weight portion 13 and the second glass substrate 12 by a predetermined distance.
After the formation of the recess 41, as shown in FIG. 18, a photoresist film (not shown) is further patterned on the silicon support layer 33, and the silicon support layer 33 is etched using the photoresist film as a mask. 14, the above-described processing steps for forming the weight part 13, the support parts 15 and 16, the outer support part 36 and the frame part 37 are performed. At this stage, the BOX layer 31 is in a connected state.

  Next, as shown in FIG. 19, the above-described removal step of removing the BOX layer 31 exposed from the silicon support layer 33 side is performed. That is, the BOX layer 31 exposed on the back surface side of each of the support parts 15 and 16 and the BOX layer 31 positioned between the outer column part 36 and the frame part 37 are removed. By performing this removal step, the support column part 14, the outer support column part 36, and the frame part 37 have a three-layer structure including a silicon active layer 32, a BOX layer 31 that is an insulating layer, and a silicon support layer 33. Between the weight portion 13 and the support portions 15 and 16, a BOX layer 31 that is an insulating layer is provided.

After the removal step, as shown in FIG. 20, the second bonding step is performed in which the silicon support layer 33 and the second glass substrate 12 are bonded by anodic bonding. Accordingly, the weight portion 13 is supported by the support portions 15 and 16 in a state where the weight portion 13 is separated from the second glass substrate 12 by a predetermined distance.
Next, as shown in FIG. 21, a photoresist film (not shown) is patterned on the silicon active layer 32, and the recess 40 is formed by edging the silicon active layer 32 using the photoresist film as a mask. Through this recess forming process, the support column 14, the support units 15 and 16, the outer support column 36 and the frame unit 37, that is, the upper portion of the fixed unit 17 can be formed. At this stage, the upper portions of the outer column part 36 and the frame part 37 are integrally formed.

Next, as shown in FIG. 22, impurities are implanted into the entire surface of the silicon active layer 32 by ion implantation, impurity diffusion, or the like, so that the upper surface of the column portion 14, the outer column portion 36 and the frame portion 37, that is, the fixed portion 17. The impurity formation step of forming the high-concentration impurity layer 35 on the upper surface of the piezoresistive element and forming the piezoresistive element 19 on the entire surface of the support portions 15 and 16 is performed.
Next, as shown in FIG. 23, a photoresist film (not shown) is patterned on the silicon active layer 32, and the silicon active layer 32 is etched using the photoresist film as a mask, so that the outer column portion 36 and the frame portion 37 are processed. Respectively.

Next, as shown in FIG. 24, the first glass substrate 11 in which the through holes 38 are formed is arranged such that each through hole 38 is located on the upper surface of the support column 14 and the upper surface of the outer support column 36, respectively. A second bonding step is performed in which the glass substrate 11 and the silicon active layer 32 are bonded by anodic bonding. As a result, the weight portion 13 formed in an annular shape is supported by the support portions 15 and 16 with a predetermined distance from the first glass substrate 11 and the second glass substrate 12.
Next, as shown in FIG. 25, a conductor thin film is formed or a conductor material is injected into at least the inner peripheral surface of the plurality of through holes 38 formed in the first glass substrate 11, and the input electrode 18 and the output electrode The acceleration sensor 10 can be manufactured by performing the electrode forming step of forming the electrode 20.
As described above, the acceleration sensor 10 may be manufactured by bonding the second glass substrate 12 first from the silicon support layer 33 side. The effect of the acceleration sensor 10 manufactured by this manufacturing method is the same as that of the above embodiment.

  Further, in the above embodiment, the weight portion 13 is formed in an annular shape having a regular tetragonal cross section with the column portion 14 as the center. However, as shown in FIG. You may form in the state close | similar to the vicinity. By carrying out like this, the weight of the weight part 13 can be increased as much as possible. Therefore, the moment can be increased and the sensitivity can be further improved.

In the above embodiment, each piezoresistive element 19 is electrically connected to the impurity layer 35 of the column 14 and the impurity layer 35 of the outer column 36 via the silicon active layer 32. As shown in FIG. 27, the metal film 45 may be formed so that the piezoresistive element 19 and the impurity layer 35 are electrically connected during the impurity implantation step. By doing so, a current can flow without passing through the silicon active layer 32, so that the resistance value decreases and the current flows easily. Thereby, while improving S / N ratio, power consumption can be suppressed and performance improvement can be aimed at.
Moreover, as shown in FIG. 27, you may form so that the upper part of the support | pillar part 14 and the outer side support | pillar part 36 may become a slope. This makes it easier to form the metal film 45.

In the above embodiment, the piezoresistive element 19 is provided on the entire upper surface of each of the support portions 15 and 16, but the present invention is not limited to this. For example, as shown in FIGS. In this case, the piezoresistive element 19 may be formed over the entire length of the support portions 15 and 16 with a width smaller than the lateral width of the support portions 15 and 16.
By doing so, the change in resistance due to the torsional stress can be reduced to reduce the erroneous output as much as possible, and the acceleration in the direction in which the support portions 15 and 16 are bent can be measured with higher accuracy.

Further, in the impurity implantation step, as shown in FIGS. 30 and 31, each piezoresistive element 19 is formed so as to be divided into two at the region where the support portions 15 and 16 and the weight portion 13 intersect. At the same time, a metal film 46 is formed on the upper surface of the support parts 15 and 16 in a range where the support parts 15 and 16 intersect with the weight part 13, and the piezoresistive element 19 divided into two by the metal film 46 is electrically connected. It doesn't matter.
By doing so, the weight portion 13 is supported, and the portion that does not contribute to displacement detection without generating stress can be bypassed by the metal film 46, so that the electrical resistance can be further reduced and the piezoresistive element 19 Sensitivity can be further improved.

  Moreover, in the said embodiment, the fixing | fixed part 17 has the four outer support | pillar parts 36 and the frame part 37, and the other end sides 15b and 16b of each support part 15 and 16 were each fixed to the outer support | pillar part 36. However, for example, as shown in FIGS. 32 and 33, only the frame portion 37 is used as the fixing portion 17, and the other end sides 15b and 16b of the support portions 15 and 16 are fixed to the frame portion 37, respectively. It doesn't matter. In this case, the region 37a to which the other end sides 15b and 16b of the support portions 15 and 16 are fixed may be configured to have an island shape. By doing so, the current flowing through each piezoresistive element 19 does not flow to the other piezoresistive elements 19 via the frame portion 37, and mechanical element separation can be ensured. In particular, since the outer support portion 36 is unnecessary, the size can be further reduced.

  Moreover, in the said embodiment, while forming the weight part 13 in the cross-sectional regular square shape, the length of the X-axis support part 15 and the Y-axis support part 16 was comprised in the same length, respectively, For example, it shows in FIG. As described above, the weight portion 13 may be formed in a rectangular cross section, and the X-axis support portion 15 and the Y-axis support portion 16 may have different lengths. By doing so, biaxial acceleration measurement can be performed in a state where the sensitivity of other axes is reduced.

  Moreover, in the said embodiment, although it was set as the structure which provided the X-axis support part 15 and the Y-axis support part 16, it is not restricted to this case, For example, as shown in FIG. A uniaxial configuration in which only the support portion 116) is provided may be employed. In this way, further downsizing can be achieved.

  Moreover, in the said embodiment, although the glass substrate was employ | adopted as a 1st board | substrate and a 2nd board | substrate, it is not limited to a glass substrate, You may use the board | substrate which does not have insulation. In this case, an insulating layer or an insulating film is provided so as to electrically insulate between the input electrode 18 and the output electrode 20 and between the support column portion 14 and the outer support column portion 36, and What is necessary is just to comprise so that a leak current may not flow into the piezoresistive element 19.

  In the above embodiment, a reference piezoresistive element for temperature compensation may be provided inside the frame portion 37. Normally, the characteristics (resistance sensitivity) of the piezoresistive element 19 change when the ambient temperature changes. By referring to the reference piezoresistive element, an error signal due to the temperature change can be canceled. it can. Therefore, since acceleration can be measured without being affected by ambient temperature changes, more accurate measurement can be performed. The reference piezoresistive element is preferably manufactured in the same shape and size as each piezoresistive element 19.

Moreover, although the said embodiment demonstrated to the example the electronic device which protects a hard disk using an acceleration, it is not restricted to this case. For example, you may employ | adopt the game controller which has the acceleration sensor 10 of this invention as an electronic device.
Further, the acceleration sensor 10 of the present invention may be employed in a vehicle air bag actuation system, a car theft system, various security systems, a robot posture control circuit, and the like.

It is a block diagram which shows one Embodiment of the electronic device which has an acceleration sensor which concerns on this invention. It is sectional drawing of the acceleration sensor shown in FIG. It is a perspective view which shows the internal structure of the support part and weight part periphery of the acceleration sensor shown in FIG. FIG. 4 is a top view of the acceleration sensor when the state shown in FIG. 3 is viewed from above. It is a cross-sectional arrow AA figure shown in FIG. FIG. 3 is a process diagram for manufacturing the acceleration sensor shown in FIG. 2 by the acceleration sensor manufacturing method according to the present invention, and is a cross-sectional view showing an SOI substrate serving as a start substrate. FIG. 7 is a process diagram in the case of manufacturing the acceleration sensor shown in FIG. 2 by the acceleration sensor manufacturing method according to the present invention, and is a cross-sectional view showing a state in which a recess is formed in the silicon active layer from the state shown in FIG. 6. . FIG. 8 is a process diagram in the case of manufacturing the acceleration sensor shown in FIG. 2 by the acceleration sensor manufacturing method according to the present invention, in which impurities are implanted into the entire surface of the silicon active layer from the state shown in FIG. 2 is a cross-sectional view showing a state in which a piezoresistive element is formed. FIG. 9 is a process diagram in the case of manufacturing the acceleration sensor shown in FIG. 2 by the acceleration sensor manufacturing method according to the present invention, in which the silicon active layer is etched from the state shown in FIG. It is sectional drawing which shows the state which formed each upper part. FIG. 3 is a process diagram when the acceleration sensor shown in FIG. 2 is manufactured by the acceleration sensor manufacturing method according to the present invention, and shows a state in which a plurality of through holes are formed at predetermined positions of the first glass substrate. . FIG. 10 is a process diagram in the case of manufacturing the acceleration sensor shown in FIG. 2 by the method for manufacturing the acceleration sensor according to the present invention, in which the first glass substrate shown in FIG. 10 is bonded to the silicon active layer from the state shown in FIG. 9. It is sectional drawing which shows the state which carried out. FIG. 12 is a process diagram in the case of manufacturing the acceleration sensor shown in FIG. 2 by the method for manufacturing an acceleration sensor according to the present invention, and is a cross-sectional view showing a state in which a recess is formed in the silicon support layer from the state shown in FIG. 11. . FIG. 13 is a process diagram in the case of manufacturing the acceleration sensor shown in FIG. 2 by the acceleration sensor manufacturing method according to the present invention, and further etching the silicon support layer from the state shown in FIG. It is sectional drawing which shows the state which formed the part, the support part, the weight part, and the support | pillar part. FIG. 14 is a process diagram when the acceleration sensor shown in FIG. 2 is manufactured by the method for manufacturing an acceleration sensor according to the present invention, and is a cross-sectional view showing a state in which an exposed extra BOX layer is removed from the state shown in FIG. 13. FIG. FIG. 15 is a process diagram when the acceleration sensor shown in FIG. 2 is manufactured by the acceleration sensor manufacturing method according to the present invention, and shows a state in which the second glass substrate is bonded to the silicon support layer from the state shown in FIG. 14. It is sectional drawing. FIG. 5 is a process diagram in the case of manufacturing the acceleration sensor shown in FIG. 2 by another acceleration sensor manufacturing method according to the present invention, and is a cross-sectional view showing an SOI substrate serving as a start substrate. FIG. 17 is a process diagram when the acceleration sensor shown in FIG. 2 is manufactured by another acceleration sensor manufacturing method according to the present invention, and is a cross-sectional view showing a state in which a recess is formed in the silicon support layer from the state shown in FIG. 16. It is. FIG. 18 is a process diagram in the case of manufacturing the acceleration sensor shown in FIG. 2 by another acceleration sensor manufacturing method according to the present invention, and further etching the silicon support layer from the state shown in FIG. It is sectional drawing which shows the state which each formed the outer pillar part, the support part, the weight part, and the lower part of the pillar part. FIG. 19 is a process diagram in the case of manufacturing the acceleration sensor shown in FIG. 2 by another acceleration sensor manufacturing method according to the present invention, and shows a state in which an exposed extra BOX layer is removed from the state shown in FIG. 18. It is sectional drawing shown. FIG. 20 is a process diagram in the case of manufacturing the acceleration sensor shown in FIG. 2 by another acceleration sensor manufacturing method according to the present invention, in which the second glass substrate is bonded to the silicon support layer from the state shown in FIG. 19. FIG. FIG. 21 is a process diagram when the acceleration sensor shown in FIG. 2 is manufactured by another acceleration sensor manufacturing method according to the present invention, and is a cross-sectional view showing a state in which a recess is formed in the silicon active layer from the state shown in FIG. 20. It is. FIG. 22 is a process diagram in the case of manufacturing the acceleration sensor shown in FIG. 2 by another acceleration sensor manufacturing method according to the present invention, in which impurities are implanted into the entire surface of the silicon active layer from the state shown in FIG. It is sectional drawing which shows the state in which the impurity layer and the piezoresistive element were each formed. FIG. 23 is a process diagram in the case of manufacturing the acceleration sensor shown in FIG. 2 by another acceleration sensor manufacturing method according to the present invention, in which the silicon active layer is etched from the state shown in FIG. It is sectional drawing which shows the state in which the part was formed, respectively. FIG. 24 is a process diagram in the case of manufacturing the acceleration sensor shown in FIG. 2 by another acceleration sensor manufacturing method according to the present invention, in which a plurality of through holes are formed in the silicon active layer from the state shown in FIG. 23. It is sectional drawing which shows the state which joined the glass substrate of 1. FIG. FIG. 25 is a process diagram when the acceleration sensor shown in FIG. 2 is manufactured by another acceleration sensor manufacturing method according to the present invention, in which input electrodes and output electrodes are respectively formed in a plurality of through holes from the state shown in FIG. 24. It is sectional drawing which shows the state which carried out. It is a figure which shows the other acceleration sensor which concerns on this invention, Comprising: It is a top view of the weight part and support part periphery of the acceleration sensor in which the weight part was formed to the position near the frame part. It is a figure which shows the other acceleration sensor which concerns on this invention, Comprising: It is sectional drawing of the acceleration sensor by which the impurity layer and the piezoresistive element were electrically connected by the metal film. It is a figure which shows the other acceleration sensor which concerns on this invention, Comprising: It is a top view of the weight part of an acceleration sensor with which the width | variety of a piezoresistive element is smaller than the width | variety of a support part, and a support part periphery. It is a cross-sectional arrow BB figure shown in FIG. FIG. 5 is a diagram showing another acceleration sensor according to the present invention, in which a piezoresistive element is divided into two at a region where a weight portion and a support portion intersect, and a piezoresistive element divided into two by a metal film is bypassed It is a top view of the weight part and support part periphery of a sensor. It is a cross-sectional arrow CC figure shown in FIG. It is a figure which shows the other acceleration sensor which concerns on this invention, Comprising: It is a top view of the weight part of an acceleration sensor by which the other end side of a support part is being fixed to the flame | frame part, and a support part periphery. It is a cross-sectional arrow DD figure shown in FIG. It is a figure which shows the other acceleration sensor which concerns on this invention, Comprising: It is a top view of the weight part of an acceleration sensor from which the length of an X-axis support part differs from a Y-axis support part, and a support part. It is a figure which shows the other acceleration sensor which concerns on this invention, Comprising: It is a top view of the weight part of a uniaxial acceleration sensor which has only an X-axis support part, and a support part periphery. It is a top view of the weight part and support part periphery which shows an example of the conventional acceleration sensor. It is a top view of the weight part and support part periphery which shows another example of the conventional acceleration sensor. It is a cross-sectional arrow EE figure shown in FIG. It is sectional drawing which shows the state which the support part of the acceleration sensor shown in FIG. 37 deform | transformed into the longitudinal direction. It is sectional drawing which shows the state which the support part of the acceleration sensor shown in FIG. 37 deform | transformed in the transversal direction.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Electronic device 10 Acceleration sensor 11 1st glass substrate (1st board | substrate)
12 Second glass substrate (second substrate)
13 Weight part 14 Supporting part 15 X-axis support part (a pair of support parts)
16 Y-axis support part (a pair of support parts)
17 Fixed portion 18 Input electrode 19 Piezoresistive element 20 Output electrode 30 SOI substrate 31 BOX layer (insulating layer, silicon oxide film)
32 Silicon active layer (first silicon layer)
33 Silicon support layer (second silicon layer)
35 Impurity layer 36 Outer strut 37 Frame (outer frame)
38 Through hole 45, 46 Metal film

Claims (20)

A first substrate and a second substrate arranged in parallel with each other at a predetermined interval;
An annular weight portion made of a semiconductor material sandwiched between the first substrate and the second substrate with a predetermined interval therebetween;
A column-shaped columnar portion made of a semiconductor material provided at substantially the center of the weight portion and sandwiched between the first substrate and the second substrate;
One end side is fixed in a state where the support column is sandwiched, and the other end side extends in a direction parallel to the surfaces of the first substrate and the second substrate. A pair of support parts made of a semiconductor material that supports the weight part in a suspended state between,
A fixing portion made of a semiconductor material that is sandwiched between the first substrate and the second substrate and fixes the other end of the pair of support portions;
An input electrode provided on the first substrate in a state of being electrically connected to the support column, and capable of applying a predetermined voltage to the support column;
A piezoresistive element that is provided on the surface of each of the pair of support portions, and whose electrical resistance changes according to the stress acting on the support portions;
An output electrode provided in a state of being electrically connected to the fixed portion on the first substrate and taking out a resistance change of the piezoresistive element through the fixed portion;
Between the support portion and the weight portion, as well as the support portion and the fixing portion, an insulating layer that electrically separates the support portion is provided,
The first substrate and the second substrate are electrically insulated between the input electrode and the output electrode and between the support column and the fixing unit. Acceleration sensor featuring. The acceleration sensor according to claim 1,
A plurality of the pair of support portions are provided at predetermined angles around the support column,
The acceleration sensor, wherein the piezoresistive element and the output electrode are provided according to the number of the pair of support portions. The acceleration sensor according to claim 1 or 2,
The fixing portion is sandwiched between the first substrate and the second substrate, and a columnar outer support portion for fixing the other end sides of the pair of support portions independently, and a first substrate And an outer frame portion that surrounds the outer support column from the periphery, and is sandwiched between the first substrate and the second substrate. The acceleration sensor according to claim 3.
The acceleration sensor, wherein the weight part is formed to the vicinity of the outer frame part. The acceleration sensor according to any one of claims 1 to 4,
The acceleration sensor according to claim 1, wherein an impurity layer is formed in a range in contact with the input electrode and the output electrode at the support portion and the fixing portion. The acceleration sensor according to claim 5, wherein
An acceleration sensor comprising a metal film that electrically connects the impurity layer and the piezoresistive element. The acceleration sensor according to any one of claims 1 to 6,
The acceleration sensor, wherein the piezoresistive element is provided over the entire length of the support portion with a width smaller than the lateral width of the support portion. The acceleration sensor according to any one of claims 1 to 6,
The piezoresistive element is divided into two regions with a region where the support portion and the weight portion intersect, and a metal film provided on the surface of the support portion within a range where the support portion and the weight portion intersect with each other. An acceleration sensor characterized by being electrically connected via The acceleration sensor according to any one of claims 1 to 8,
The acceleration sensor, wherein the first substrate and the second substrate are glass substrates.   An electronic apparatus comprising the acceleration sensor according to claim 1. An SOI substrate formed by sandwiching a silicon oxide film between the first silicon layer and the second silicon layer, and the SOI substrate sandwiched from both sides by the first substrate and the second substrate. A method of manufacturing a joined acceleration sensor, comprising:
A concave portion is formed in the first silicon layer, and one end side is fixed with the upper portion of the columnar support portion sandwiched between the support portions, and the surfaces of the first substrate and the second substrate. A recess forming step for forming an upper portion of a pair of support portions whose other end side extends in a parallel direction with respect to each other, and an upper portion of a fixing portion for fixing the other end side of the pair of support portions;
Impurity implantation for injecting impurities into the surface of the first silicon layer after the recess forming step and forming a piezoresistive element whose electrical resistance changes according to the stress acting on the support portion on the surface of the support portion Process,
After the impurity implantation step, the first substrate and the first silicon are formed so that a through hole is formed at a predetermined position of the first substrate, and the through hole is positioned on the upper surface of the support column and the fixing unit, respectively. A first joining step for joining the layers;
After the first bonding step, the second silicon layer is processed, and the strut portion, the fixing portion, the pair of support portions, and between the one end side and the other end side of the pair of support portions, A process of forming a weight part that is supported in a state of being suspended from a pair of support parts and that is formed in an annular shape with a predetermined distance from the first substrate and the second substrate. Process,
After the processing step, a removal step of removing the silicon oxide film exposed on the back side of the pair of support parts;
A second bonding step for bonding the second substrate to the second silicon layer after the removing step;
After the second bonding step, a conductive thin film is formed in each through-hole or a conductive material is injected, and an input electrode that is electrically connected to the support column and can apply a predetermined voltage to the support column; An electrode forming step of forming an output electrode electrically connected to the fixed portion and taking out a resistance change of the piezoresistive element,
The first substrate and the second substrate are in an electrically insulated state between the input electrode and the output electrode and between the support column and the fixing unit. A method for manufacturing an acceleration sensor. An SOI substrate formed by sandwiching a silicon oxide film between the first silicon layer and the second silicon layer, and the SOI substrate sandwiched from both sides by the first substrate and the second substrate. A method of manufacturing a joined acceleration sensor, comprising:
The second silicon layer is processed so that one end side is fixed in a state where the columnar column part is sandwiched between the lower part of the columnar column part, and the surface of the first substrate and the second substrate is fixed. The lower part of the pair of support parts whose other end side extends in the parallel direction, the lower part of the fixing part that fixes the other end side of the pair of support parts, and between the one end side and the other end side of the pair of support parts A weight portion formed in an annular shape with a predetermined interval from the first substrate and the second substrate is formed while being supported by the pair of support portions. Processing steps,
After the processing step, a removal step of removing the silicon oxide film exposed on the back side of the pair of support parts;
A first bonding step of bonding the second substrate to the second silicon layer after the removing step;
After the first bonding step, forming a recess in the first silicon layer, forming a recess, forming the support column, the pair of support units, and the fixing unit, respectively.
After the recess forming step, impurities are implanted into the surface of the first silicon layer, and a piezoresistive element whose electrical resistance changes according to the stress acting on the support portions is formed on the surfaces of the pair of support portions. An impurity implantation step;
After the impurity implantation step, the first substrate and the first silicon are formed so that a through hole is formed at a predetermined position of the first substrate, and the through hole is positioned on the upper surface of the support column and the fixing unit, respectively. A second joining step for joining the layers;
After the second bonding step, a conductive thin film is formed in each through-hole or a conductive material is injected, and an input electrode that is electrically connected to the support column and can apply a predetermined voltage to the support column; An electrode forming step of forming an output electrode electrically connected to the fixed portion and taking out a resistance change of the piezoresistive element,
The first substrate and the second substrate are in an electrically insulated state between the input electrode and the output electrode and between the support column and the fixing unit. A method for manufacturing an acceleration sensor. In the manufacturing method of the acceleration sensor according to claim 11 or 12,
When performing the recess forming step and the processing step, a plurality of the pair of support portions is formed at a predetermined angle around the support column portion,
When the impurity implantation step, the first bonding step or the second bonding step, and the electrode forming step are performed, the piezoresistive element and the output electrode are set according to the number of the pair of support portions. A method for manufacturing an acceleration sensor, comprising: forming an acceleration sensor. In the manufacturing method of the acceleration sensor according to any one of claims 11 to 13,
When performing the recess forming step and the processing step, a columnar outer column portion for independently fixing the other end sides of the pair of support portions and an outer frame portion surrounding the outer column portion from the periphery are formed. And manufacturing the acceleration sensor. In the manufacturing method of the acceleration sensor according to claim 14,
A method of manufacturing an acceleration sensor, wherein the weight portion is formed up to the vicinity of the outer frame portion in the processing step. In the manufacturing method of the acceleration sensor according to any one of claims 11 to 15,
In the impurity implantation step, an impurity layer is formed on the upper surface of the column portion and the upper surface of the fixed portion. The acceleration sensor manufacturing method according to any one of claims 11 to 16,
A method of manufacturing an acceleration sensor, wherein the impurity layer and the piezoresistive element are electrically connected by a metal film during the impurity implantation step. In the manufacturing method of the acceleration sensor according to any one of claims 11 to 17,
In the impurity implantation step, the piezoresistive element is formed over the entire length of the support portion with a width smaller than the lateral width of the support portion. In the manufacturing method of the acceleration sensor according to any one of claims 11 to 17,
In the impurity implantation step, the piezoresistive element is formed so as to bisect the region where the support portion and the weight portion intersect with each other, and the support portion and the weight portion intersect with each other. A method of manufacturing an acceleration sensor, comprising: forming a metal film on an upper surface; and electrically connecting piezoresistive elements divided into two by the metal film. In the manufacturing method of the acceleration sensor according to any one of claims 11 to 19,
The method for manufacturing an acceleration sensor, wherein the first substrate and the second substrate are glass substrates.

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