JP2010048700A - Mems and method for manufacturing mems - Google Patents

Mems and method for manufacturing mems Download PDF

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JP2010048700A
JP2010048700A JP2008213953A JP2008213953A JP2010048700A JP 2010048700 A JP2010048700 A JP 2010048700A JP 2008213953 A JP2008213953 A JP 2008213953A JP 2008213953 A JP2008213953 A JP 2008213953A JP 2010048700 A JP2010048700 A JP 2010048700A
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flexible
flexible portion
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detection
mems
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Yasuo Okumiya
保郎 奥宮
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Yamaha Corp
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Abstract

<P>PROBLEM TO BE SOLVED: To provide an MEMS with a flexible portion having high detection preciseness of a deflection and to provide a method for manufacturing the MEMS. <P>SOLUTION: In an orthogonal coordinate system having three axes of an x-axis, a y-axis, and a z-axis, the MEMS includes a support section, the flexible portion that protrudes in the direction x from the support section and is formed to be thin in the direction z, a weight section W connected to a top end of the flexible portion and a distortion detection means. The distortion detection means is provided at a detection region which is an xy region in a detection interval of an x interval in the vicinity of a boundary between the flexible portion and the support section and in the vicinity of the center of the flexible portion in the direction y, and is adapted to detect a distortion in accordance with displacement of the top end of the flexible portion in the direction z. Each of the cross sectional faces of the flexible portion along the directions y and z in regions at both outsides of the detection region in the detection interval is formed in such a manner that a cross sectional area of a half part relatively away from the detection area is wider than that of the remaining half part. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

本発明はＭＥＭＳ（Micro Electro Mechanical Systems）およびＭＥＭＳ製造方法に関する。   The present invention relates to a MEMS (Micro Electro Mechanical Systems) and a MEMS manufacturing method.

従来、錘部に結合された可撓部の変形を電気信号に変換することにより加速度、角速度、振動などを検出するＭＥＭＳが知られている。ピエゾ抵抗素子、圧電素子などの歪み検出手段によって可撓部の変形を電気信号として検出する場合、歪みは撓みによってもねじれによっても生ずるため、１つの歪み検出手段の出力からは可撓部が撓んでいるのかねじれているのかを特定できない。特許文献１には梁の両側面にピエゾ抵抗素子を配置することにより、ピエゾ抵抗素子の出力に含まれる梁のねじれ成分を相殺する加速度センサが開示されている。特許文献２には、梁の縁部が酸化シリコンで構成され、梁の残部がシリコンで構成された加速度センサが開示されている。
特開平１０−３２３４１号公報 特開２００１−５６３４３号公報 2. Description of the Related Art Conventionally, a MEMS that detects acceleration, angular velocity, vibration, and the like by converting deformation of a flexible portion coupled to a weight portion into an electrical signal is known. When the deformation detection means such as a piezoresistive element or a piezoelectric element detects deformation of the flexible portion as an electric signal, the distortion is caused by either bending or twisting, so that the flexible portion is bent from the output of one strain detection means. It is not possible to determine whether it is twisted or twisted. Patent Document 1 discloses an acceleration sensor that cancels out the torsional component of the beam included in the output of the piezoresistive element by disposing piezoresistive elements on both sides of the beam. Patent Document 2 discloses an acceleration sensor in which the edge of the beam is made of silicon oxide and the remainder of the beam is made of silicon.
JP-A-10-32341 JP 2001-56343 A

特許文献１に記載された加速度センサにおいては、シリコンウエハの表裏にピエゾ抵抗素子を形成し、その後にシリコンウエハを切削するときに梁の厚さが決まるため、梁の厚さのばらつきが大きくなるという問題がある。また特許文献１の加速度センサでは、梁の幅が広くなければピエゾ抵抗素子の出力に含まれる梁のねじれ成分を相殺することができないため、梁の撓み剛性が結果的に高まる。したがって特許文献１の加速度センサでは、梁の撓みの検出感度の低下と梁のねじれ成分の相殺効果とはトレードオフの関係になる。   In the acceleration sensor described in Patent Document 1, since the thickness of the beam is determined when piezoresistive elements are formed on the front and back surfaces of the silicon wafer and the silicon wafer is subsequently cut, variation in the thickness of the beam increases. There is a problem. Further, in the acceleration sensor of Patent Document 1, since the torsional component of the beam included in the output of the piezoresistive element cannot be canceled unless the beam is wide, the bending rigidity of the beam is increased as a result. Therefore, in the acceleration sensor of Patent Document 1, a decrease in the detection sensitivity of the beam deflection and the effect of canceling the torsional component of the beam are in a trade-off relationship.

特許文献２に記載された加速度センサにおいては、梁がねじれるときに応力が集中する梁の縁部がシリコンよりも硬い酸化シリコンからなるため、梁のねじれが抑制される。しかし、梁の熱膨張係数が均一でないと、温度変化により梁が変形しやすくなる。このため、特許文献２に記載された技術を適用すると加速度センサの温度特性が悪くなるという問題がある。   In the acceleration sensor described in Patent Document 2, since the edge portion of the beam where stress concentrates when the beam is twisted is made of silicon oxide harder than silicon, twisting of the beam is suppressed. However, if the thermal expansion coefficient of the beam is not uniform, the beam is likely to be deformed due to temperature changes. For this reason, when the technique described in Patent Document 2 is applied, there is a problem that the temperature characteristics of the acceleration sensor are deteriorated.

本発明はこれらの問題を解決しつつＭＥＭＳの可撓部の撓み検出精度を高めることを目的の１つとする。   An object of the present invention is to improve the accuracy of detecting the deflection of the flexible portion of the MEMS while solving these problems.

（１）上記目的を達成するためのＭＥＭＳは、ｘ軸、ｙ軸およびｚ軸を直交座標系の３軸とするとき、支持部と、支持部からｘ方向に突出しｚ方向に薄い膜状の可撓部と、可撓部の突端に結合している錘部と、可撓部と支持部との境界に対して近傍のｘ区間である検出区間にあるｘｙ領域であってｙ方向において可撓部の中心に対して近傍のｘｙ領域である検出領域に設けられ可撓部の突端のｚ方向の変位に応じた歪みを検出するための歪み検出手段と、を備え、検出区間にあって検出領域より外側の両方にある領域における可撓部のｙｚ断面は、それぞれ、検出領域から相対的に遠い方の半分の部分の断面積が残部の断面積よりも広い形態である。
本発明によると、可撓部の撓みを検出するための歪み検出手段が設けられる検出区間における可撓部の断面が検出区間のねじれを抑制する形態であるため、可撓部の撓み検出精度が高まる。さらに本発明によると、可撓部の撓みを検出するための歪み検出手段が設けられる検出区間における可撓部の断面がねじれほどには撓みを抑制しない形態であるため、可撓部の撓み検出感度の低下が抑制される。なお、可撓部の突端のｚ方向の変位に応じて生ずる可撓部の変形が可撓部の撓みであり、可撓部の突端が固定端に対してｘ軸周りに相対的に回転する可撓部の変形が可撓部のねじれである。 (1) The MEMS for achieving the above object is a thin film in the z direction that protrudes from the support portion and the support portion in the x direction when the x axis, the y axis, and the z axis are three axes of the orthogonal coordinate system. It is an xy region in a detection section that is an x section in the vicinity of the boundary between the flexible section, the weight section coupled to the protruding end of the flexible section, and the flexible section and the support section, and can be used in the y direction. A strain detecting means for detecting a strain corresponding to the displacement in the z direction of the tip of the flexible portion provided in a detection region that is a nearby xy region with respect to the center of the flexible portion; The yz cross section of the flexible part in both the regions outside the region has a form in which the cross sectional area of the half portion relatively far from the detection region is wider than the cross sectional area of the remaining part.
According to the present invention, since the cross section of the flexible section in the detection section provided with the strain detection means for detecting the bending of the flexible section is a form that suppresses the twist of the detection section, the deflection detection accuracy of the flexible section is high. Rise. Further, according to the present invention, since the cross section of the flexible portion in the detection section in which the strain detecting means for detecting the bending of the flexible portion is provided has a form that does not suppress the bending as much as the torsion, A decrease in sensitivity is suppressed. The deformation of the flexible portion that occurs in accordance with the displacement of the protruding end of the flexible portion in the z direction is the bending of the flexible portion, and the protruding end of the flexible portion rotates relative to the fixed end about the x axis. The deformation of the flexible part is a twist of the flexible part.

（２）上記目的を達成するためのＭＥＭＳにおいて、検出区間において可撓部はｘ方向にリブが延びるリブ構造を有してもよい。   (2) In the MEMS for achieving the above object, the flexible part may have a rib structure extending in the x direction in the detection section.

（３）上記目的を達成するためのＭＥＭＳにおいて、リブが検出区間のｙ方向の縁の両方に形成されていてもよい。
可撓部がねじれるときには検出区間のｙ方向（幅方向）の縁に応力が集中するため、そこにリブを形成することによって検出区間において可撓部がねじれにくくなる。 (3) In the MEMS for achieving the above object, ribs may be formed on both edges in the y direction of the detection section.
When the flexible portion is twisted, stress concentrates on the edge in the y direction (width direction) of the detection section. Therefore, forming the rib there makes the flexible portion difficult to twist in the detection section.

（４）上記目的を達成するためのＭＥＭＳにおいて、リブは、可撓部のｙ方向の縁の両方において可撓部と支持部との境界から可撓部の突端の手前まで延びていてもよい。
本発明によると、ｘ方向においてリブが可撓部の端から端まで延びていないため、リブが延びている区間においては可撓部がねじれにくい一方で、リブが延びていない区間では可撓部のねじれが抑制されない。その結果、１個の可撓部の全体ではねじれが抑制されにくくなる。１個の可撓部の全体でのねじれが抑制されにくくなると、１個の可撓部をねじるように錘部に作用する力も検出する場合には、その力の検出感度の低下が抑制される。 (4) In the MEMS for achieving the above object, the rib may extend from the boundary between the flexible portion and the support portion to the front of the tip of the flexible portion at both edges in the y direction of the flexible portion. .
According to the present invention, since the rib does not extend from end to end in the x direction, the flexible portion is not easily twisted in the section where the rib extends, but the flexible section in the section where the rib does not extend. Is not suppressed. As a result, it is difficult for the entire flexible portion to be twisted. When it becomes difficult to suppress the torsion of one flexible part as a whole, when a force acting on the weight part is detected so as to twist one flexible part, a decrease in detection sensitivity of the force is suppressed. .

（５）上記目的を達成するためのＭＥＭＳにおいて、リブが検出領域に形成されていてもよい。
リブには応力が集中するため、本発明によると可撓部の撓みによる応力が検出領域に集中する。したがって可撓部の撓み検出感度が高まる。 (5) In the MEMS for achieving the above object, a rib may be formed in the detection region.
Since stress concentrates on the rib, according to the present invention, stress due to bending of the flexible portion concentrates on the detection region. Therefore, the bending detection sensitivity of the flexible portion is increased.

（６）上記目的を達成するためのＭＥＭＳにおいて、リブの幅はｚ方向の突端に向かって漸減していてもよい。
本発明によると、過度の応力集中による可撓部の破損を防止できる。 (6) In the MEMS for achieving the above object, the width of the rib may be gradually decreased toward the tip in the z direction.
According to the present invention, it is possible to prevent the flexible portion from being damaged due to excessive stress concentration.

（７）上記目的を達成するためのＭＥＭＳにおいて、可撓部のｘｙ方向に広がる主面の一方は凹部と残部とからなり、可撓部の厚さは残部に向かって漸増していてもよい。
本発明によると、過度の応力集中による可撓部の破損を防止できる。 (7) In the MEMS for achieving the above object, one of the main surfaces extending in the xy direction of the flexible part may be composed of a recessed part and a remaining part, and the thickness of the flexible part may gradually increase toward the remaining part. .
According to the present invention, it is possible to prevent the flexible portion from being damaged due to excessive stress concentration.

（８）上記目的を達成するためのＭＥＭＳにおいて、検出区間は可撓部と支持部との境界を含んでもよい。   (8) In the MEMS for achieving the above object, the detection section may include a boundary between the flexible portion and the support portion.

可撓部が撓むとき、応力は可撓部と支持部との境界を含む領域に集中するからである。   This is because when the flexible portion bends, the stress is concentrated in a region including the boundary between the flexible portion and the support portion.

（９）上記目的を達成するためのＭＥＭＳにおいて、可撓部が検出領域を除いて均質であってもよい。
本発明によると、温度変化による可撓部の変形を抑制できる。 (9) In the MEMS for achieving the above object, the flexible part may be uniform except for the detection region.
According to the present invention, deformation of the flexible portion due to temperature change can be suppressed.

（１０）上記目的を達成するためのＭＥＭＳにおいて、可撓部はシリコンからなり、検出領域には、ピエゾ抵抗素子を形成するための不純物が拡散していてもよい。
歪み検出手段としてピエゾ抵抗素子を用いることにより、低い周波数領域において可撓部の撓み検出感度を高めることができる。 (10) In the MEMS for achieving the above object, the flexible part may be made of silicon, and an impurity for forming a piezoresistive element may be diffused in the detection region.
By using a piezoresistive element as the strain detecting means, it is possible to increase the deflection detection sensitivity of the flexible portion in a low frequency region.

（１１）上記目的を達成するためのＭＥＭＳにおいて、歪み検出手段は、可撓部と錘部との境界に対して近傍のｘ区間である第二の検出区間にあるｘｙ領域であってｙ方向において可撓部の中心に対して近傍のｘｙ領域である第二の検出領域にも設けられていてもよい。   (11) In the MEMS for achieving the above object, the strain detection means is an xy region in a second detection section which is a nearby x section with respect to the boundary between the flexible part and the weight part, and is in the y direction. In the second detection area, which is an xy area in the vicinity of the center of the flexible part.

（１２）上記目的を達成するためのＭＥＭＳ製造方法は、ｘ軸、ｙ軸およびｚ軸を直交座標系の３軸とするとき、支持部と、支持部からｘ方向に突出しｚ方向において薄い膜状の可撓部と、可撓部の突端に結合している錘部と、可撓部と支持部との境界に対して近傍のｘ区間である検出区間にある領域であってｙ方向において可撓部の中心に対して近傍のｘｙ領域である検出領域に設けられ可撓部の突端のｚ方向の変位に応じた歪みを検出するための歪み検出手段と、を備えるＭＥＭＳ製造方法である。この製造方法は、シリコンからなる部分の熱酸化された表層をエッチングすることにより、検出区間にあって検出領域より外側の両方にある領域における可撓部のｙｚ断面を、それぞれ、検出領域から相対的に遠い方の半分の部分の断面積が残部の断面積よりも広い形態にすることを含む。
本発明によると、熱酸化にともなう拡散が生ずるため、応力が過度に集中しにくい断面形態を有する可撓部を形成できる。 (12) A MEMS manufacturing method for achieving the above object includes a support portion and a thin film protruding in the x direction from the support portion and thin in the z direction when the x axis, the y axis, and the z axis are three axes of the orthogonal coordinate system. A region in a detection section, which is an x section in the vicinity of the boundary between the flexible section and the support section, in the y direction. A strain detection means provided in a detection region that is a nearby xy region with respect to the center of the flexible portion, and a strain detection means for detecting strain according to the displacement in the z direction of the tip of the flexible portion. . In this manufacturing method, by etching the thermally oxidized surface layer of the portion made of silicon, the yz cross section of the flexible portion in the region that is both in the detection section and outside the detection region is relative to the detection region, respectively. The cross-sectional area of the far half is wider than the cross-sectional area of the remainder.
According to the present invention, since diffusion occurs due to thermal oxidation, it is possible to form a flexible portion having a cross-sectional shape in which stress is hardly concentrated.

１．原理
はじめに後述する実施形態に適用される本発明の原理を説明する。説明の便宜を図るため、図２に示すように、可撓部３１が支持部３２から突出する方向と平行にｘ軸を定め、膜状の可撓部３１の幅方向と平行にｙ軸を定め、可撓部３１の厚さ方向と平行にｚ軸を定める。 1. Principle First, the principle of the present invention applied to the embodiments described later will be described. For convenience of explanation, as shown in FIG. 2, the x-axis is defined parallel to the direction in which the flexible portion 31 protrudes from the support portion 32, and the y-axis is defined in parallel to the width direction of the film-like flexible portion 31. The z axis is determined in parallel with the thickness direction of the flexible portion 31.

１−１ 検出手段を設ける領域
錘部Ｗが突端３１ａに結合された膜状の可撓部３１の撓みに応じた歪みを精度良く検出するため、歪み検出手段は、薄い膜状の可撓部３１の撓みを感度良く検出でき、可撓部３１のねじれを検出しにくい領域に設けられる。すなわち以下に詳述するように、検出手段は可撓部３１が撓むときの歪みが大きく、可撓部３１が捻れるときの歪みが小さい領域に設けられる。 1-1 Area in which the detection means is provided In order to accurately detect the strain corresponding to the deflection of the film-like flexible part 31 in which the weight part W is coupled to the protrusion 31a, the strain detection means is a thin film-like flexible part. It is provided in a region where the flexure of 31 can be detected with high sensitivity and the twist of the flexible portion 31 is difficult to detect. That is, as will be described in detail below, the detecting means is provided in a region where the strain when the flexible portion 31 is bent is large and the strain when the flexible portion 31 is twisted is small.

支持部３２の厚さを可撓部３１に対して十分厚く設定することにより、可撓部３１の撓みに応じた応力は支持部３２と可撓部３１の境界近傍に集中する。そこで歪み検出手段は可撓部３１と支持部３２との境界に対して近傍のｘ区間である検出区間３３に設ける。歪みはほぼ可撓部３１と支持部３２との境界で最大となるため、検出区間３３は可撓部３１と支持部３２との境界を跨いでいることが望ましい。実質的に歪みが生じない範囲にまで検出区間３３を設定するとかえって感度が落ちるため、検出区間３３は可撓部３１と支持部３２との境界に対して近傍に限定される。   By setting the thickness of the support portion 32 to be sufficiently thick with respect to the flexible portion 31, the stress corresponding to the bending of the flexible portion 31 is concentrated near the boundary between the support portion 32 and the flexible portion 31. Therefore, the strain detection means is provided in the detection section 33 which is an x section near the boundary between the flexible portion 31 and the support portion 32. Since the distortion is maximized at the boundary between the flexible part 31 and the support part 32, it is desirable that the detection section 33 straddles the boundary between the flexible part 31 and the support part 32. If the detection section 33 is set to a range where distortion is not substantially generated, the sensitivity is lowered. Therefore, the detection section 33 is limited to the vicinity of the boundary between the flexible portion 31 and the support portion 32.

図３Ｂおよび図３Ｃに示すように厚さが幅方向（ｙ方向）において一定の可撓部３１がねじれるとき、可撓部３１に生じる応力は図４に示すように可撓部３１の幅方向（ｙ方向）の縁から中心に近くなるに従い小さくなり、可撓部３１の幅方向の中心線上では理論上ゼロとなる。可撓部３１の撓みによる歪みを検出する場合は、可撓部３１のねじれにより生じる歪みを検出しないことが望ましい。このために、可撓部３１のねじれによる応力がほぼゼロになる可撓部３１の幅方向の中心線上に検出手段を設けることが望ましい。撓み検出手段を可撓部３１の中心線上に設けられない場合、可撓部３１の中心線に出来る限り近い領域に検出手段を設ければよい。検出手段が可撓部３１の中心線上に設けられる場合、検出手段を設けるｙ方向の幅が狭いほど、ねじれによる歪みが検出されにくくなる。   3B and 3C, when the flexible portion 31 having a constant thickness in the width direction (y direction) is twisted, the stress generated in the flexible portion 31 is the width direction of the flexible portion 31 as shown in FIG. It becomes smaller as it gets closer to the center from the edge in the (y direction), and theoretically becomes zero on the center line in the width direction of the flexible portion 31. When detecting the distortion due to the bending of the flexible part 31, it is desirable not to detect the distortion caused by the twist of the flexible part 31. For this purpose, it is desirable to provide detection means on the center line in the width direction of the flexible portion 31 where the stress due to the twist of the flexible portion 31 is substantially zero. When the deflection detection means is not provided on the center line of the flexible part 31, the detection means may be provided in a region as close as possible to the center line of the flexible part 31. When the detection unit is provided on the center line of the flexible portion 31, the distortion due to torsion is less likely to be detected as the width in the y direction in which the detection unit is provided is narrower.

したがって、可撓部３１の撓みに応じた歪みを検出するため検出手段は、図２Ａに示すように可撓部３１と支持部３２との境界に対して近傍であり、かつ、可撓部３１の中心に対して近傍のｘｙ領域である検出領域３４に設けられる。例えば検出手段の長さの１％程度が支持部３２に位置し残部が可撓部３１に位置するように設定すればよい。   Therefore, the detecting means for detecting the strain corresponding to the bending of the flexible part 31 is close to the boundary between the flexible part 31 and the support part 32 as shown in FIG. Is provided in the detection region 34 which is an xy region in the vicinity of the center. For example, it may be set so that about 1% of the length of the detection means is located on the support portion 32 and the remaining portion is located on the flexible portion 31.

１−２ 可撓部の断面形状
図３Ｂおよび図３Ｃに示すように厚さが幅方向（ｙ方向）において一定の可撓部３１がねじれるとき、可撓部３１に生じる応力は図４に示すように可撓部３１の幅方向の中心から縁に近くなるに従い大きくなる。したがって、任意のｘ区間にある可撓部３１の幅方向の縁近傍において可撓部３１の剛性が小さくなればその区間において可撓部３１がねじれにくくなる。可撓部３１の幅方向の縁近傍における剛性は可撓部３１の幅方向の縁近傍部分のｙｚ断面積との相関が高い。検出手段が設けられるｘ区間である検出区間３３において可撓部３１がねじれにくくなると、検出区間３３内にあって可撓部３１の中心に対して近傍のｘｙ領域である検出領域３４に生ずる歪みは小さくなる。 1-2 Cross-sectional shape of flexible portion When the flexible portion 31 having a constant thickness in the width direction (y direction) is twisted as shown in FIGS. 3B and 3C, the stress generated in the flexible portion 31 is shown in FIG. Thus, it becomes large as it approaches the edge from the center in the width direction of the flexible portion 31. Therefore, if the rigidity of the flexible part 31 is reduced in the vicinity of the edge in the width direction of the flexible part 31 in an arbitrary x section, the flexible part 31 is difficult to twist in that section. The rigidity in the vicinity of the edge in the width direction of the flexible portion 31 has a high correlation with the yz cross-sectional area of the vicinity of the edge in the width direction of the flexible portion 31. When the flexible section 31 is difficult to twist in the detection section 33 that is the x section where the detection means is provided, the distortion that occurs in the detection area 34 that is in the detection section 33 and is in the vicinity of the center of the flexible section 31 is the xy area. Becomes smaller.

一方、図５Ａに示すように厚さが幅方向（ｙ方向）において一定の可撓部３１がねじれずに撓むとき、可撓部３１に生じる応力は図５Ｂに示すように可撓部３１の幅方向において一定である。また可撓部３１の厚さが幅方向において一定でないとしても、可撓部３１がねじれずに撓むときの曲率は可撓部３１の幅方向において一定である。そして可撓部３１がねじれずに撓むとき、微小なｘ区間における可撓部３１の曲率は、その区間における可撓部３１の剛性との相関が高く、その区間における可撓部３１のｙｚ断面形状との相関は低い。微小なｘ区間における可撓部３１の剛性はその区間における可撓部３１のｙｚ断面積との相関が高い。   On the other hand, when the flexible portion 31 having a constant thickness in the width direction (y direction) is bent without being twisted as shown in FIG. 5A, the stress generated in the flexible portion 31 is the flexible portion 31 as shown in FIG. 5B. It is constant in the width direction. Even if the thickness of the flexible portion 31 is not constant in the width direction, the curvature when the flexible portion 31 bends without being twisted is constant in the width direction of the flexible portion 31. When the flexible portion 31 bends without twisting, the curvature of the flexible portion 31 in the minute x section is highly correlated with the rigidity of the flexible portion 31 in the section, and yz of the flexible portion 31 in the section is high. The correlation with the cross-sectional shape is low. The rigidity of the flexible portion 31 in the minute x section has a high correlation with the yz cross-sectional area of the flexible portion 31 in the section.

したがって、検出手段が設けられるｘ区間である検出区間３３において可撓部３１を捻れにくくするために可撓部３１の幅方向の縁近傍部分のｙｚ断面積を大きくしても、それに応じて可撓部３１の幅方向の中心近傍部分のｙｚ断面積を小さくすれば、検出区間における可撓部３１の撓みによる歪みの減少を抑制できる。このように可撓部３１が捻れにくく撓みやすくなる検出区間３３における可撓部３１のｙｚ断面形状を図６Ａから図６Ｅに例示した。図６Ａに示すように可撓部３１の幅方向（ｙ方向）の両側の縁においてｘ方向に延びる凸部であるリブ３１ｂを設けてもよい。図６Ｂに示すように可撓部３１の幅方向の両側の縁からわずかに中心よりの２カ所においてｘ方向に延びるリブ３１ｂを設けてもよい。図６Ｃに示すように可撓部３１の幅方向の中心から縁に向かってリブ３１ｂの配列密度が高くなるようにｘ方向に延びる４つ以上のリブ３１ｂを設けてもよい。図６Ｄに示すように可撓部３１の厚さが可撓部３１の幅方向の中心から縁に向かって漸増してもよい。図６Ａから図６Ｅに例示するように、可撓部３１のｙｚ断面形状は、検出区間３３において相対的に可撓部３１の幅方向の縁近傍部分のｙｚ断面積が大きく可撓部３１の幅方向の中心近傍部分のｙｚ断面積が小さければどのように設計しても良く、どの程度までねじれ成分の混入による撓み検出精度の誤差を許すかという観点や、撓み検出感度をどの程度求めるかという観点や、製造の容易さの観点などによって適宜設計すればよい。なお、図６Ｅに示すように可撓部３１の幅方向の中心線上に設けられたリブ３１ｂは、可撓部３１のねじれよりも撓みを抑制する。しかしながら、微小なｘ区間における曲率（応力がゼロになる仮想面の曲率）が同じであれば、可撓部３１が厚いほど可撓部３１の表面の歪みは大きくなる。そこで撓みの検出感度が高まる範囲においてリブ３１ｂの高さと幅を設計すれば、リブ３１ｂを可撓部３１の幅方向の中心線上に設けることによって撓みの検出感度を高めることもできる。   Therefore, even if the yz cross-sectional area of the vicinity of the edge in the width direction of the flexible portion 31 is increased in order to make the flexible portion 31 difficult to twist in the detection section 33 that is the x section in which the detection means is provided, it is possible accordingly. If the yz cross-sectional area of the central portion in the width direction of the flexible portion 31 is reduced, it is possible to suppress a decrease in distortion due to the deflection of the flexible portion 31 in the detection section. 6A to 6E illustrate the yz cross-sectional shape of the flexible portion 31 in the detection section 33 in which the flexible portion 31 is not easily twisted and easily bent. As shown in FIG. 6A, ribs 31 b that are convex portions extending in the x direction may be provided at both edges in the width direction (y direction) of the flexible portion 31. As shown in FIG. 6B, ribs 31b extending in the x-direction may be provided at two locations slightly from the center from both edges in the width direction of the flexible portion 31. As shown in FIG. 6C, four or more ribs 31b extending in the x direction may be provided so that the arrangement density of the ribs 31b increases from the center in the width direction of the flexible portion 31 toward the edge. As shown in FIG. 6D, the thickness of the flexible portion 31 may gradually increase from the center in the width direction of the flexible portion 31 toward the edge. As illustrated in FIGS. 6A to 6E, the yz cross-sectional shape of the flexible portion 31 has a relatively large yz cross-sectional area near the edge in the width direction of the flexible portion 31 in the detection section 33. Any design is possible as long as the yz cross-sectional area near the center in the width direction is small. To what extent is the error in deflection detection accuracy allowed due to mixing of torsional components, and how much deflection detection sensitivity is obtained? The design may be made as appropriate according to the viewpoint of the above, the viewpoint of ease of manufacture, and the like. As shown in FIG. 6E, the rib 31 b provided on the center line in the width direction of the flexible portion 31 suppresses bending more than the twist of the flexible portion 31. However, if the curvature in the minute x section (the curvature of the virtual surface where the stress is zero) is the same, the thicker the flexible portion 31, the greater the distortion of the surface of the flexible portion 31. Therefore, if the height and width of the rib 31b are designed within a range in which the detection sensitivity of bending is increased, the detection sensitivity of bending can be increased by providing the rib 31b on the center line in the width direction of the flexible portion 31.

したがって、検出手段が設けられる検出領域３４より外側の両方にある領域における可撓部３１のｙｚ断面が、それぞれ、検出領域３４から相対的に遠い方の半分の部分のｙｚ断面積が残部のｙｚ断面積よりも大きい形態を採用することにより、検出区間３３における可撓部３１のねじれを抑制しつつ検出区間３３における可撓部３１の撓みによる歪みの減少を抑制できる。また、これにより可撓部３１のねじれに対する強度が高まるという副次的な効果も期待できる。   Therefore, the yz cross section of the flexible portion 31 in both the regions outside the detection region 34 where the detection means is provided is the yz cross sectional area of the half portion farther from the detection region 34, respectively. By adopting a form larger than the cross-sectional area, it is possible to suppress a decrease in distortion due to the bending of the flexible portion 31 in the detection section 33 while suppressing the twist of the flexible section 31 in the detection section 33. Moreover, the secondary effect that the intensity | strength with respect to the twist of the flexible part 31 increases by this can also be anticipated.

１−３ リブの長さとねじれ抑制効果
図７Ａに示すようにリブ３１ｂが可撓部３１のｙ方向の縁の両方において可撓部３１と支持部３２との境界から可撓部３１の突端の手前まで延びている構成では、可撓部３１にはリブ３１ｂのないｘ区間３１ｄがあることになる。この構成では、可撓部３１の突端３１ａをねじる力が作用した場合に、ねじれにより検出区間３３に生ずる歪みをリブ３１ｂが抑制する一方で、可撓部３１の全体のねじれが抑制されにくくなる。なぜならば、リブ３１ｂによって可撓部３１の検出区間３３がねじれにくくなっても、リブ３１ｂの無いｘ区間３１ｄにおいては可撓部３１のねじれが抑制されていないため、可撓部３１をねじる力によって検出区間３３に生ずるはずの歪みがリブ３１ｂの無いｘ区間３１ｄに分散するからである。その結果、検出区間３３における可撓部３１のねじれがさらに抑制されるとともに、１個の可撓部３１の全体ではねじれが抑制されにくくなる。 1-3 Rib Length and Twist Suppressing Effect As shown in FIG. 7A, the rib 31 b extends from the boundary between the flexible portion 31 and the support portion 32 at both ends of the flexible portion 31 in the y direction. In the configuration extending to the near side, the flexible portion 31 has the x section 31d without the rib 31b. In this structure, when the force which twists the protrusion 31a of the flexible part 31 acts, while the rib 31b suppresses the distortion which arises in the detection area 33 by twist, it becomes difficult to suppress the whole twist of the flexible part 31. . This is because even if the detection section 33 of the flexible portion 31 is not easily twisted by the rib 31b, the twist of the flexible portion 31 is not suppressed in the x section 31d without the rib 31b. This is because the distortion that should occur in the detection section 33 is dispersed in the x section 31d without the rib 31b. As a result, the twist of the flexible portion 31 in the detection section 33 is further suppressed, and the twist of the single flexible portion 31 is hardly suppressed.

このように可撓部３１にリブ３１ｂのないｘ区間３１ｄがある構成を２次元または３次元の加速度または角速度を検出するセンサ等に適用すると、ある方向の成分を検出するための１個の可撓部３１のねじれを抑制することによりその方向に直交する方向の成分の検出感度が低下することを抑制する効果を得られる。   When the configuration in which the flexible section 31 has the x section 31d without the rib 31b is applied to a sensor or the like that detects two-dimensional or three-dimensional acceleration or angular velocity, one possible component for detecting a component in a certain direction is possible. By suppressing the torsion of the flexible portion 31, it is possible to obtain an effect of suppressing a decrease in detection sensitivity of a component in a direction orthogonal to the direction.

１−４ 可撓部の表面形態
図８は可撓部３１の表面形態を示すｙｚ断面図である。可撓部３１の断面積または表面形態がステップ状に変化すると、その境界に応力が集中する。したがって、図８Ａから図８Ｄに示すようにリブ３１ｂの幅（ｙ方向の長さ）をｚ方向の突端に向かって漸減させることにより、可撓部３１のリブ３１ｂと残部３１ｃの境界において断面積および表面形態をなだらかに変化させることが望ましい。すなわち可撓部３１の厚さは凹部から凸部に向かって漸増していることが好ましい。また、可撓部３１のリブ３１ｂと残部３１ｃの境界において可撓部３１の表面は図８Ｃおよび図８Ｄに示すようになだらかに湾曲していることがさらに好ましい。 1-4 Surface Form of Flexible Part FIG. 8 is a yz sectional view showing the surface form of the flexible part 31. When the cross-sectional area or the surface form of the flexible portion 31 changes in a step shape, stress concentrates on the boundary. Therefore, as shown in FIGS. 8A to 8D, the cross-sectional area at the boundary between the rib 31b and the remaining portion 31c of the flexible portion 31 is obtained by gradually decreasing the width (length in the y direction) of the rib 31b toward the tip in the z direction. It is desirable to change the surface morphology gently. That is, it is preferable that the thickness of the flexible portion 31 gradually increases from the concave portion toward the convex portion. Further, it is more preferable that the surface of the flexible portion 31 is gently curved as shown in FIGS. 8C and 8D at the boundary between the rib 31b and the remaining portion 31c of the flexible portion 31.

このように可撓部３１の厚さを凹部から凸部に向かって漸増させることによって、可撓部３１に過度の力が生じた場合でも、可撓部３１が破断しにくくなる。また、可撓部３１の凹部と凸部とにまたがって可撓部３１の表面に配線などを形成する工程において生ずる断線などの不具合を低減できる。   Thus, by gradually increasing the thickness of the flexible portion 31 from the concave portion toward the convex portion, even when an excessive force is generated in the flexible portion 31, the flexible portion 31 is difficult to break. In addition, it is possible to reduce problems such as disconnection that occurs in the process of forming a wiring or the like on the surface of the flexible portion 31 across the concave portion and the convex portion of the flexible portion 31.

１−５ 可撓部の材質
熱膨張係数の異なる材質からなる複数の層で可撓部３１を構成すると、周囲温度の変化により撓みやねじれが可撓部３１に生じる。これらの撓みやねじれは検出精度を低下させる。したがって可撓部３１の熱膨張係数は均質であることが好ましい。 1-5 Material of Flexible Part When the flexible part 31 is composed of a plurality of layers made of materials having different thermal expansion coefficients, the flexible part 31 is bent or twisted due to a change in ambient temperature. These deflections and twists reduce detection accuracy. Therefore, it is preferable that the thermal expansion coefficient of the flexible portion 31 is uniform.

以下、上述した本発明の原理を適用した実施の形態を添付図面を参照しながら説明する。各図において対応する構成要素には同一の符号が付され、重複する説明は省略される
２．第一実施形態
図１Ａ、図１Ｂおよび図１Ｃは本発明のＭＥＭＳの第一実施形態としての加速度センサ１００の要部を示している。図１Ｂは図１ＡにおけるＢ−Ｂ断面図である。図１Ｃは図１ＡにおけるＣ−Ｃ断面図である。
加速度センサ１００は支持部１１２と、支持部１１２にそれぞれ結合している４つの可撓部１１１と、４つの可撓部１１１と結合している錘部Ｗと、支持部１１２と可撓部１１１の境界近傍に形成された複数のピエゾ抵抗素子Ｒとを備えている。図１Ｂおよび図１Ｃにおいてこれらの機能要素の境界は実線によって示されている。これらの機能要素はガラス層３１９、厚いシリコン（Ｓｉ）層３１３、二酸化シリコン（ＳｉＯ２）層３１２、薄いシリコン層３１１などで構成されている。すなわち加速度センサ１００は薄膜の積層構造を有する固体素子である。図１Ｂおよび図１Ｃにおいてこれらのこれらの層の境界は破線によって示されている。 Hereinafter, embodiments to which the above-described principle of the present invention is applied will be described with reference to the accompanying drawings. In each figure, corresponding components are denoted by the same reference numerals, and redundant description is omitted. First Embodiment FIG. 1A, FIG. 1B and FIG. 1C show a main part of an acceleration sensor 100 as a first embodiment of the MEMS of the present invention. 1B is a cross-sectional view taken along the line BB in FIG. 1A. 1C is a cross-sectional view taken along the line CC in FIG. 1A.
The acceleration sensor 100 includes a support portion 112, four flexible portions 111 coupled to the support portion 112, a weight portion W coupled to the four flexible portions 111, a support portion 112, and the flexible portion 111. And a plurality of piezoresistive elements R formed in the vicinity of the boundary. In FIG. 1B and FIG. 1C, the boundaries of these functional elements are indicated by solid lines. These functional elements include a glass layer 319, a thick silicon (Si) layer 313, a silicon dioxide (SiO 2 ) layer 312 and a thin silicon layer 311. That is, the acceleration sensor 100 is a solid element having a thin film laminated structure. In FIGS. 1B and 1C, the boundaries of these layers are indicated by dashed lines.

支持部１１２は矩形の枠形態を有する。
４つの可撓部１１１はそれぞれ支持部１１２の内側空間の中央に位置する錘部Ｗに向かって突出している薄い膜状の片持ち梁の形態である。４つの可撓部１１１と錘部Ｗとは十字形態に結合している。加速度が生ずると、それぞれの可撓部１１１の突端に結合している錘部Ｗに慣性力が作用するためそれぞれの可撓部１１１が変形する。一直線に並ぶ２つの可撓部１１１の撓みを検出することにより、その直線と平行な方向の加速度成分とｚ方向（可撓部の厚さ方向）の加速度成分とを検出できる。２つの可撓部１１１が並ぶ直線と平行な方向またはｚ方向に加速度が生ずると、２つの可撓部１１１の突端がｚ方向に変位する。 The support part 112 has a rectangular frame shape.
Each of the four flexible portions 111 is in the form of a thin film cantilever projecting toward the weight portion W located at the center of the inner space of the support portion 112. The four flexible portions 111 and the weight portion W are coupled in a cross shape. When acceleration occurs, each of the flexible portions 111 is deformed because an inertial force acts on the weight portion W coupled to the protruding end of each flexible portion 111. By detecting the bending of the two flexible portions 111 aligned in a straight line, the acceleration component in the direction parallel to the straight line and the acceleration component in the z direction (thickness direction of the flexible portion) can be detected. When acceleration occurs in a direction parallel to the straight line where the two flexible portions 111 are arranged or in the z direction, the protruding ends of the two flexible portions 111 are displaced in the z direction.

それぞれの可撓部１１１の幅方向の両縁には、支持部１１２から錘部Ｗに向かって可撓部１１１の中央より手前まで延びているリブ１１３ａと、錘部Ｗから支持部１１２に向かって可撓部１１１の中央より手前まで延びているリブ１１３ｂとが形成されている。これらのリブ１１３はピエゾ抵抗素子Ｒが設けられる区間における可撓部１１１の捻れを抑制する。可撓部１１１の長手方向の中心近傍の区間にはリブ１１３が形成されていない。したがって可撓部１１１の１つに着目すると、その可撓部１１１のねじれはピエゾ抵抗素子Ｒが設けられている区間において抑制されている一方で、全体としては抑制されていない。その結果、全ての可撓部１１１が撓みやすくなっている。   At both edges in the width direction of each flexible portion 111, ribs 113 a extending from the center of the flexible portion 111 toward the front from the support portion 112 toward the weight portion W, and from the weight portion W toward the support portion 112. Thus, a rib 113b extending from the center of the flexible portion 111 to the near side is formed. These ribs 113 suppress the twist of the flexible portion 111 in the section where the piezoresistive element R is provided. The rib 113 is not formed in a section near the center of the flexible portion 111 in the longitudinal direction. Therefore, when attention is paid to one of the flexible portions 111, the twist of the flexible portion 111 is suppressed in the section where the piezoresistive element R is provided, but is not suppressed as a whole. As a result, all the flexible portions 111 are easily bent.

それぞれの可撓部１１１の幅方向の中心近傍には、支持部１１２から錘部Ｗに向かって可撓部１１１の中央より手前まで延びているリブ１１３ｃ、１１３ｄ、１１３ｊと、錘部Ｗから支持部１１２に向かって可撓部１１１の中央より手前まで延びているリブ１１３ｅ、１１３ｆ、１１３ｉとが形成されている。これらのリブ１１３ｃ、１１３ｄ、１１３ｅ、１１３ｆは可撓部１１１のピエゾ抵抗素子Ｒが設けられる表層の歪みを増大させる。ピエゾ抵抗素子Ｒが設けられないリブ１１３ｉ、１１３ｊは可撓部１１１のｙｚ断面を対称形にするために形成されている。   In the vicinity of the center in the width direction of each flexible portion 111, ribs 113c, 113d, 113j extending from the support portion 112 toward the weight portion W toward the near side from the center of the flexible portion 111, and the weight portion W are supported. Ribs 113e, 113f, and 113i extending from the center of the flexible portion 111 toward the front toward the portion 112 are formed. These ribs 113c, 113d, 113e, 113f increase the distortion of the surface layer on which the piezoresistive element R of the flexible portion 111 is provided. The ribs 113i and 113j not provided with the piezoresistive element R are formed to make the yz section of the flexible portion 111 symmetrical.

可撓部１１１の撓みを検出するためにピエゾ抵抗素子Ｒがそれぞれの可撓部１１１に設けられる。可撓部１１１と支持部１１２との境界近傍に設けられるピエゾ抵抗素子Ｒは可撓部１１１の突端のｚ方向の変位に応じた歪みを検出するための歪み検出手段として機能する。本実施形態では、加速度の互いに直交する３軸の成分を検出するため、各軸４個、合計１２個が４つの可撓部１１１に設けられている。２つの可撓部１１１が並ぶ直線と平行な方向（ｘ方向およびｙ方向）の加速度成分を検出するためのピエゾ抵抗素子Ｒは可撓部１１１の幅方向の中心線上に位置するリブ１１３ｄ、１１３ｅの表層に設けられる。ｚ方向の加速度を検出するためのピエゾ抵抗素子Ｒは可撓部１１１の幅方向の中心近傍に位置するリブ１１３ｃ、１１３ｆの表層に設けられる。   In order to detect the bending of the flexible part 111, the piezoresistive element R is provided in each flexible part 111. The piezoresistive element R provided in the vicinity of the boundary between the flexible portion 111 and the support portion 112 functions as a strain detection means for detecting strain according to the displacement of the protruding end of the flexible portion 111 in the z direction. In this embodiment, in order to detect the three-axis components of the acceleration orthogonal to each other, four of each axis, a total of twelve, are provided in the four flexible portions 111. The piezoresistive element R for detecting the acceleration component in the direction parallel to the straight line where the two flexible portions 111 are arranged (x direction and y direction) is a rib 113d, 113e located on the center line in the width direction of the flexible portion 111. It is provided on the surface layer. The piezoresistive element R for detecting the acceleration in the z direction is provided on the surface layer of the ribs 113 c and 113 f located in the vicinity of the center in the width direction of the flexible portion 111.

図１０〜図１５、図１９および図２０は図１のＣ−Ｃ断面において加速度センサ１００の製造工程を示している。図１６〜図１８は図１のＢ−Ｂ断面において加速度センサ１００の製造工程を示している。加速度センサ１００は例えば次のようにして製造される。   10 to 15, 19, and 20 show the manufacturing process of the acceleration sensor 100 in the CC cross section of FIG. 1. 16 to 18 show a manufacturing process of the acceleration sensor 100 in the BB cross section of FIG. The acceleration sensor 100 is manufactured as follows, for example.

最初に図１０に示すように厚いシリコン層３１３と二酸化シリコン層３１２と薄いシリコン層３１１とが積層されたＳＯＩ基板３１４（Silicon On Insulator）を準備する。   First, as shown in FIG. 10, an SOI substrate 314 (Silicon On Insulator) in which a thick silicon layer 313, a silicon dioxide layer 312 and a thin silicon layer 311 are stacked is prepared.

次に図１１に示すように薄いシリコン層３１１の表面に酸化シリコン層３１５と窒化シリコン層３１６を例えばＣＶＤ（Chemical Vapor Deposition）により形成する。   Next, as shown in FIG. 11, a silicon oxide layer 315 and a silicon nitride layer 316 are formed on the surface of the thin silicon layer 311 by, for example, CVD (Chemical Vapor Deposition).

次に図１２に示すように窒化シリコン層３１６を例えばＣＦ４＋Ｏ２、ＣＨＦ３ガスにてドライエッチングして無機マスク３１７を形成する。 Next, as shown in FIG. 12, the inorganic mask 317 is formed by dry-etching the silicon nitride layer 316 with, for example, CF 4 + O 2 or CHF 3 gas.

次に図１３に示すように無機マスク３１７を保護膜として用いて薄いシリコン層３１１の表層を熱酸化する。熱酸化では酸素（Ｏ２）が無機マスク３１７の開口から拡散するため、二酸化シリコン層３１５の一部が拡大し、薄いシリコン層３１１と二酸化シリコン層３１５とのなだらかな界面が形成される。 Next, as shown in FIG. 13, the surface layer of the thin silicon layer 311 is thermally oxidized using the inorganic mask 317 as a protective film. In thermal oxidation, oxygen (O 2 ) diffuses from the opening of the inorganic mask 317, so that a part of the silicon dioxide layer 315 is enlarged and a gentle interface between the thin silicon layer 311 and the silicon dioxide layer 315 is formed.

次に図１４に示すように二酸化シリコン層３１５の無機マスク３１７から露出している部分を例えばＣＦ４＋Ｏ２、ＣＨＦ３ガスによるドライエッチングにより除去する。その結果、可撓部１１１の主面の一方が形成される。すなわち可撓部１１１の主面の一方にリブ１１３の表面形状が形成される。前工程において熱酸化によって拡大した二酸化シリコン層３１８とシリコン層３１１との界面がなだらかであるため、可撓部１１１の厚さは薄肉部１１４からリブ１１３を構成する残部に向かって漸増する。 Next, as shown in FIG. 14, the portion of the silicon dioxide layer 315 exposed from the inorganic mask 317 is removed by dry etching using, for example, CF 4 + O 2 or CHF 3 gas. As a result, one of the main surfaces of the flexible part 111 is formed. That is, the surface shape of the rib 113 is formed on one of the main surfaces of the flexible portion 111. Since the interface between the silicon dioxide layer 318 and the silicon layer 311 enlarged by thermal oxidation in the previous step is gentle, the thickness of the flexible portion 111 gradually increases from the thin portion 114 toward the remaining portion constituting the rib 113.

次に図１５と図１６に示すように薄いシリコン層３１１の一部の表層に不純物イオンを注入する。その結果、薄いシリコン層３１１の一部の表層には、不純物イオンが拡散し、ピエゾ抵抗素子Ｒが形成される。   Next, as shown in FIGS. 15 and 16, impurity ions are implanted into a part of the surface layer of the thin silicon layer 311. As a result, impurity ions diffuse in a part of the surface layer of the thin silicon layer 311 to form the piezoresistive element R.

次に図１７に示すようにコンタクトホール１１７を有する表層絶縁膜１１６とピエゾ抵抗素子Ｒの配線１１５とを形成する。可撓部１１１の厚さは薄肉部１１４から残部に向かって漸増する形態であるので、配線１１５の厚みを小さくしても配線１１５が断線することがない。   Next, as shown in FIG. 17, a surface insulating film 116 having a contact hole 117 and a wiring 115 of the piezoresistive element R are formed. Since the thickness of the flexible portion 111 gradually increases from the thin portion 114 toward the remaining portion, the wiring 115 is not disconnected even if the thickness of the wiring 115 is reduced.

次に図１８に示すように、薄いシリコン層３１１を例えばＳＦ６ガスによる反応性イオンエッチング等でエッチングすることにより可撓部１１１の輪郭と支持部１１２および錘部Ｗの薄いシリコン層３１１からなる部分の輪郭を形成する。 Next, as shown in FIG. 18, the thin silicon layer 311 is etched by, for example, reactive ion etching using SF 6 gas, and the like, thereby forming the outline of the flexible portion 111 and the thin silicon layer 311 of the support portion 112 and the weight portion W. The contour of the part is formed.

次に図１９と図２０に示すように、厚いシリコン層３１３をＤｅｅｐ−ＲＩＥ（Ｃ４Ｆ８プラズマとＳＦ６プラズマによる所謂ボッシュプロセス）によってエッチングすることにより支持部１１２および錘部Ｗの厚いシリコン層３１３からなる部分の輪郭を形成する。 Next, as shown in FIGS. 19 and 20, the thick silicon layer 313 is etched by deep-RIE (a so-called Bosch process using C 4 F 8 plasma and SF 6 plasma) to thereby thicken the support portion 112 and the weight portion W. The contour of the portion composed of the layer 313 is formed.

次にガラスウエハを厚いシリコン層３１３に直接接合した後にガラスウエハをダイサーで切断することによって支持部１１２および錘部Ｗのガラス層３１９からなる部分の輪郭を形成する。その後、ダイシング、パッケージングなどの工程を実施すると加速度センサ１００が完成する   Next, after the glass wafer is directly bonded to the thick silicon layer 313, the glass wafer is cut with a dicer to form the contour of the support portion 112 and the portion made of the glass portion 319 of the weight portion W. Thereafter, the acceleration sensor 100 is completed when processes such as dicing and packaging are performed.

尚、図１３と図１４で用いた製造工程の換わりに、無機マスク３１７を保護膜として用いてイオン注入をおこなった後に、イオン注入により形成された不純物拡散部の除去をおこなってもよい。   Instead of the manufacturing process used in FIGS. 13 and 14, the impurity diffusion portion formed by ion implantation may be removed after ion implantation using the inorganic mask 317 as a protective film.

また、図１２〜図１４で用いた製造工程の換わりに、図２１で示すようにフォトレジスト３２１をマスクとして用いてＲＩＥ（反応性イオンエッチング）等によってエッチングした後に、フォトレジスト３２１を除去し、図２２に示すように熱酸化により薄いシリコン層３１１の表面に酸化シリコン層３２０を形成し、その後、酸化シリコン層３２０をエッチングにより除去してもよい。これにより薄肉部１１４とリブ１１３とにおける可撓部１１１の厚さの差を大きくすることができる。   Further, instead of the manufacturing process used in FIGS. 12 to 14, after etching by RIE (reactive ion etching) using the photoresist 321 as a mask as shown in FIG. 21, the photoresist 321 is removed, As shown in FIG. 22, a silicon oxide layer 320 may be formed on the surface of the thin silicon layer 311 by thermal oxidation, and then the silicon oxide layer 320 may be removed by etching. Thereby, the difference of the thickness of the flexible part 111 in the thin part 114 and the rib 113 can be enlarged.

また、可撓部３１の材質はシリコンに限るものではなく、化合物半導体やセラミック等でもよい。また、錘部Ｗの材質はガラスに限るものではなく、金属やセラミック等でもよい。また、エッチングの方法はＤｅｅｐ−ＲＩＥやＲＩＥのドライエッチングに限るものではなく、ウエットエッチングでもよい。   The material of the flexible portion 31 is not limited to silicon, and may be a compound semiconductor, ceramic, or the like. Moreover, the material of the weight part W is not limited to glass, but may be metal, ceramic, or the like. Further, the etching method is not limited to deep-RIE or RIE dry etching, but may be wet etching.

３．第二実施形態
図９Ａ、図９Ｂおよび図９Ｃは本発明のＭＥＭＳの第二実施形態としての加速度センサ２００の要部を示している。図９Ｂは図９ＡにおけるＢ−Ｂ断面図である。図９Ｃは図９ＡにおけるＣ−Ｃ断面図である。 3. Second Embodiment FIG. 9A, FIG. 9B and FIG. 9C show a main part of an acceleration sensor 200 as a second embodiment of the MEMS of the present invention. 9B is a cross-sectional view taken along line BB in FIG. 9A. 9C is a cross-sectional view taken along the line CC in FIG. 9A.

図９Ａに示すように加速度センサ２００のそれぞれの可撓部２１１の幅方向の両縁には、支持部２１２から錘部Ｗまで延びているリブ２１３を形成しても良い。また、ピエゾ抵抗素子Ｒは可撓部２１１の凹部２１４に設けてもよい。
４．他の実施形態 As shown in FIG. 9A, ribs 213 extending from the support portion 212 to the weight portion W may be formed on both edges in the width direction of the respective flexible portions 211 of the acceleration sensor 200. Further, the piezoresistive element R may be provided in the concave portion 214 of the flexible portion 211.
4). Other embodiments

尚、本発明の技術的範囲は、上述した実施の形態に限定されるものではなく、本発明の要旨を逸脱しない範囲内において種々変更を加え得ることは勿論である。例えば、上記実施形態で示した材質や寸法や成膜方法やパターン転写方法はあくまで例示であるし、当業者であれば自明である工程の追加や削除や工程順序の入れ替えについては説明が省略されている。また例えば、上述した製造工程において、膜の組成、成膜方法、膜の輪郭形成方法、工程順序などは、ＭＥＭＳを構成しうる物性を持つ膜材料の組み合わせや、膜厚や、要求される輪郭形状精度などに応じて適宜選択されるものであって、特に限定されない。   It should be noted that the technical scope of the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the scope of the present invention. For example, the materials, dimensions, film forming methods, and pattern transfer methods shown in the above embodiments are merely examples, and descriptions of addition and deletion of processes and replacement of process order that are obvious to those skilled in the art are omitted. ing. Also, for example, in the above-described manufacturing process, the film composition, film forming method, film outline forming method, process sequence, etc. are combinations of film materials having physical properties that can constitute MEMS, film thicknesses, and required outlines. It is appropriately selected according to the shape accuracy and the like and is not particularly limited.

また例えば圧電素子やＦＥＴを検出手段として用いてもよい。また本発明は片持ち梁形態の可撓部を１つだけ備えた１軸の加速度センサにも適用できる。また本発明は角速度センサ、振動センサなどにも適用できる。また可撓部の変形をレーザ等で検出するカンチレバーなどにも本発明を適用できる。   Further, for example, a piezoelectric element or FET may be used as the detection means. The present invention can also be applied to a uniaxial acceleration sensor having only one cantilevered flexible portion. The present invention can also be applied to angular velocity sensors, vibration sensors, and the like. The present invention can also be applied to a cantilever that detects deformation of the flexible portion with a laser or the like.

図１Ａは本発明の第一実施形態にかかる平面図。図１Ｂおよび図１Ｃは本発明の第一実施形態にかかる断面図。FIG. 1A is a plan view according to the first embodiment of the present invention. 1B and 1C are cross-sectional views according to the first embodiment of the present invention. 図２Ａは本発明の原理説明にかかる平面図。図２Ｂおよび図２Ｃは本発明の原理説明にかかる断面図。FIG. 2A is a plan view for explaining the principle of the present invention. 2B and 2C are cross-sectional views illustrating the principle of the present invention. 図３Ａは本発明の原理説明にかかる平面図。図３Ｂ、図３Ｃおよび図３Ｄは本発明の原理説明にかかる断面図。FIG. 3A is a plan view of the principle of the present invention. 3B, 3C, and 3D are cross-sectional views for explaining the principle of the present invention. 本発明の原理説明にかかる線グラフ。The line graph concerning the principle of this invention. 図５Ａは本発明の原理説明にかかる断面図。図５Ｂは本発明の原理説明にかかる線グラフ。FIG. 5A is a sectional view illustrating the principle of the present invention. FIG. 5B is a line graph for explaining the principle of the present invention. 図６Ａ、図６Ｂ、図６Ｃ、図６Ｄおよび図６Ｅは本発明の原理説明にかかる断面図。6A, FIG. 6B, FIG. 6C, FIG. 6D and FIG. 6E are cross-sectional views for explaining the principle of the present invention. 図７Ａは本発明の原理説明にかかる平面図。図７Ｂおよび図７Ｃは本発明の原理説明にかかる断面図。FIG. 7A is a plan view for explaining the principle of the present invention. 7B and 7C are cross-sectional views for explaining the principle of the present invention. 図８Ａ、図８Ｂ、図８Ｃおよび図８Ｄは本発明の原理説明にかかる断面図。8A, 8B, 8C, and 8D are sectional views according to the principle of the present invention. 図９Ａは本発明の第二実施形態にかかる平面図。図９Ｂおよび図９Ｃは本発明の第二実施形態にかかる断面図。FIG. 9A is a plan view according to the second embodiment of the present invention. 9B and 9C are cross-sectional views according to the second embodiment of the present invention. 本発明の第二実施形態にかかる製造工程を説明する断面図。Sectional drawing explaining the manufacturing process concerning 2nd embodiment of this invention. 本発明の第二実施形態にかかる製造工程を説明する断面図。Sectional drawing explaining the manufacturing process concerning 2nd embodiment of this invention. 本発明の第一実施形態にかかる製造工程を説明する断面図。Sectional drawing explaining the manufacturing process concerning 1st embodiment of this invention. 本発明の第二実施形態にかかる製造工程を説明する断面図。Sectional drawing explaining the manufacturing process concerning 2nd embodiment of this invention. 本発明の第二実施形態にかかる製造工程を説明する断面図。Sectional drawing explaining the manufacturing process concerning 2nd embodiment of this invention. 本発明の第二実施形態にかかる製造工程を説明する断面図。Sectional drawing explaining the manufacturing process concerning 2nd embodiment of this invention. 本発明の第二実施形態にかかる製造工程を説明する断面図。Sectional drawing explaining the manufacturing process concerning 2nd embodiment of this invention. 本発明の第一実施形態にかかる製造工程を説明する断面図。Sectional drawing explaining the manufacturing process concerning 1st embodiment of this invention. 本発明の第二実施形態にかかる製造工程を説明する断面図。Sectional drawing explaining the manufacturing process concerning 2nd embodiment of this invention. 本発明の第二実施形態にかかる製造工程を説明する断面図。Sectional drawing explaining the manufacturing process concerning 2nd embodiment of this invention. 本発明の第二実施形態にかかる製造工程を説明する断面図。Sectional drawing explaining the manufacturing process concerning 2nd embodiment of this invention. 本発明の第二実施形態にかかる製造工程を説明する断面図。Sectional drawing explaining the manufacturing process concerning 2nd embodiment of this invention. 本発明の第二実施形態にかかる製造工程を説明する断面図。Sectional drawing explaining the manufacturing process concerning 2nd embodiment of this invention.

符号の説明Explanation of symbols

３１：可撓部、３１ａ：突端、３１ｂ：リブ、３１ｃ：残部、３１ｄ：ｘ区間、３２：支持部、３３：検出区間、３４：検出領域、１００：加速度センサ、１１１：可撓部、１１２：支持部、１１３：リブ、１１４：残部、１１５：配線、１１６：表層絶縁層、１１７：コンタクトホール、２００：加速度センサ、２１１：可撓部、２１２：支持部、２１３：リブ、２１４：凹部、３１１：薄いシリコン層、３１２：二酸化シリコン層、３１３：厚いシリコン層、３１４：ＳＯＩ基板、３１５：酸化シリコン層、３１６：窒化シリコン層、３１７：無機マスク、３１８：二酸化シリコン、３１９：ガラス層、３２０：酸化シリコン層、３２１：フォトレジスト、Ｒ：ピエゾ抵抗素子、Ｗ：錘部 31: flexible part, 31a: protruding end, 31b: rib, 31c: remaining part, 31d: x section, 32: support part, 33: detection section, 34: detection area, 100: acceleration sensor, 111: flexible part, 112 : Support part, 113: rib, 114: remaining part, 115: wiring, 116: surface insulating layer, 117: contact hole, 200: acceleration sensor, 211: flexible part, 212: support part, 213: rib, 214: concave part , 311: Thin silicon layer, 312: Silicon dioxide layer, 313: Thick silicon layer, 314: SOI substrate, 315: Silicon oxide layer, 316: Silicon nitride layer, 317: Inorganic mask, 318: Silicon dioxide, 319: Glass layer 320: Silicon oxide layer, 321: Photoresist, R: Piezoresistive element, W: Weight part

Claims (12)

ｘ軸、ｙ軸およびｚ軸を直交座標系の３軸とするとき、
支持部と、
前記支持部からｘ方向に突出しｚ方向に薄い膜状の可撓部と、
前記可撓部の突端に結合している錘部と、
前記可撓部と前記支持部との境界に対して近傍のｘ区間である検出区間にあるｘｙ領域であってｙ方向において前記可撓部の中心に対して近傍のｘｙ領域である検出領域に設けられ前記可撓部の突端のｚ方向の変位に応じた歪みを検出するための歪み検出手段と、
を備え、
前記検出区間にあって前記検出領域より外側の両方にある領域における前記可撓部のｙｚ断面は、それぞれ、前記検出領域から相対的に遠い方の半分の部分の断面積が残部の断面積よりも広い形態である、
ＭＥＭＳ。 When the x-axis, y-axis, and z-axis are the three axes of the Cartesian coordinate system,
A support part;
A film-like flexible part protruding in the x direction from the support part and thin in the z direction;
A weight portion coupled to the protruding end of the flexible portion;
An xy region in a detection section that is an x section near the boundary between the flexible portion and the support portion, and a detection region that is an xy region in the vicinity of the center of the flexible portion in the y direction. A strain detecting means for detecting a strain corresponding to a displacement in the z direction of the protruding end of the flexible portion;
With
The yz cross section of the flexible portion in the region that is in the detection section and outside the detection region is such that the cross-sectional area of the half portion that is relatively far from the detection region is larger than the cross-sectional area of the remaining portion. A wide form,
MEMS. 前記検出区間において前記可撓部はｘ方向にリブが延びるリブ構造を有する、
請求項１に記載のＭＥＭＳ。 In the detection section, the flexible portion has a rib structure extending in the x direction.
The MEMS according to claim 1. 前記リブが前記検出区間のｙ方向の縁の両方に形成されている、
請求項２に記載のＭＥＭＳ。 The ribs are formed on both edges of the detection section in the y direction.
The MEMS according to claim 2. 前記リブは、前記可撓部のｙ方向の縁の両方において前記可撓部と前記支持部との境界から前記可撓部の突端の手前まで延びている、
請求項３に記載のＭＥＭＳ。 The ribs extend from the boundary between the flexible part and the support part to the front of the projecting end of the flexible part at both edges in the y direction of the flexible part.
The MEMS according to claim 3. 前記リブが前記検出領域に形成されている、
請求項２から４のいずれか一項に記載のＭＥＭＳ。 The rib is formed in the detection region;
The MEMS according to any one of claims 2 to 4. 前記リブの幅はｚ方向の突端に向かって漸減している、
請求項２から５のいずれか一項に記載のＭＥＭＳ。 The width of the rib gradually decreases toward the tip in the z direction.
The MEMS according to any one of claims 2 to 5. 前記可撓部のｘｙ方向に広がる主面の一方は凹部と残部とからなり、
前記可撓部の厚さは前記残部に向かって漸増している、
請求項１から６のいずれか一項に記載のＭＥＭＳ。 One of the principal surfaces extending in the xy direction of the flexible portion is composed of a recess and a remaining portion,
The thickness of the flexible part gradually increases toward the remaining part,
The MEMS according to any one of claims 1 to 6. 前記検出区間は前記可撓部と前記支持部との境界を含む、
請求項１から７のいずれか一項に記載のＭＥＭＳ。 The detection section includes a boundary between the flexible portion and the support portion.
The MEMS according to any one of claims 1 to 7. 前記可撓部は前記検出領域を除いて均質である、
請求項１から８のいずれか一項に記載のＭＥＭＳ。 The flexible part is homogeneous except for the detection region,
The MEMS according to any one of claims 1 to 8. 前記可撓部はシリコンからなり、
前記検出領域には、ピエゾ抵抗素子を形成するための不純物が拡散している、
請求項１から９のいずれか一項に記載のＭＥＭＳ。 The flexible part is made of silicon,
Impurities for forming a piezoresistive element are diffused in the detection region,
The MEMS according to any one of claims 1 to 9. 前記歪み検出手段は、前記可撓部と前記錘部との境界に対して近傍のｘ区間である第二の検出区間にあるｘｙ領域であってｙ方向において前記可撓部の中心に対して近傍のｘｙ領域である第二の検出領域にも設けられている、
請求項１から１０のいずれか一項に記載のＭＥＭＳ。 The strain detecting means is an xy region in a second detection section that is an x section in the vicinity of the boundary between the flexible portion and the weight portion, and is in the y direction with respect to the center of the flexible portion. It is also provided in the second detection area which is a nearby xy area,
The MEMS according to any one of claims 1 to 10. ｘ軸、ｙ軸およびｚ軸を直交座標系の３軸とするとき、
支持部と、
前記支持部からｘ方向に突出しｚ方向において薄い膜状の可撓部と、
前記可撓部の突端に結合している錘部と、
前記可撓部と前記支持部との境界に対して近傍のｘ区間である検出区間にある領域であってｙ方向において前記可撓部の中心に対して近傍のｘｙ領域である検出領域に設けられ前記可撓部の突端のｚ方向の変位に応じた歪みを検出するための歪み検出手段と、
を備えるＭＥＭＳの製造方法であって、
シリコンからなる部分の熱酸化された表層をエッチングすることにより、前記検出区間にあって前記検出領域より外側の両方にある領域における前記可撓部のｙｚ断面を、それぞれ、前記検出領域から相対的に遠い方の半分の部分の断面積が残部の断面積よりも広い形態にする、
ことを含むＭＥＭＳ製造方法。 When the x-axis, y-axis, and z-axis are the three axes of the Cartesian coordinate system,
A support part;
A film-like flexible part protruding from the support part in the x direction and thin in the z direction;
A weight portion coupled to the protruding end of the flexible portion;
Provided in a detection area that is in a detection section that is an x section in the vicinity of the boundary between the flexible section and the support section and that is in the vicinity of the center of the flexible section in the y direction. Strain detecting means for detecting strain according to the displacement in the z direction of the tip of the flexible portion;
A method for manufacturing a MEMS comprising:
By etching the thermally oxidized surface layer of the portion made of silicon, the yz cross section of the flexible portion in the region that is both in the detection section and outside the detection region can be relatively compared with the detection region, respectively. The cross-sectional area of the far half is wider than the cross-sectional area of the remaining part.
MEMS manufacturing method including the above.
JP2008213953A 2008-08-22 2008-08-22 Mems and method for manufacturing mems Withdrawn JP2010048700A (en)

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2013243512A (en) * 2012-05-21 2013-12-05 Seiko Epson Corp Ultrasound transducer, ultrasound probe, and ultrasound inspection device
WO2014073631A1 (en) * 2012-11-12 2014-05-15 株式会社村田製作所 Angular acceleration sensor and acceleration sensor

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2013243512A (en) * 2012-05-21 2013-12-05 Seiko Epson Corp Ultrasound transducer, ultrasound probe, and ultrasound inspection device
US9561527B2 (en) 2012-05-21 2017-02-07 Seiko Epson Corporation Ultrasonic transducer, ultrasonic probe, and ultrasonic examination device
WO2014073631A1 (en) * 2012-11-12 2014-05-15 株式会社村田製作所 Angular acceleration sensor and acceleration sensor
JPWO2014073631A1 (en) * 2012-11-12 2016-09-08 株式会社村田製作所 Angular acceleration sensor and acceleration sensor
US9903883B2 (en) 2012-11-12 2018-02-27 Murata Manufacturing Co., Ltd. Angular acceleration sensor and acceleration sensor

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