JP6582273B2 - Manufacturing method of MEMS element - Google Patents

Manufacturing method of MEMS element Download PDF

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JP6582273B2
JP6582273B2 JP2015167331A JP2015167331A JP6582273B2 JP 6582273 B2 JP6582273 B2 JP 6582273B2 JP 2015167331 A JP2015167331 A JP 2015167331A JP 2015167331 A JP2015167331 A JP 2015167331A JP 6582273 B2 JP6582273 B2 JP 6582273B2
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mems element
movable electrode
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JP2017042871A (en
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新一 荒木
新一 荒木
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New Japan Radio Co Ltd
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2224/00—Indexing scheme for arrangements for connecting or disconnecting semiconductor or solid-state bodies and methods related thereto as covered by H01L24/00
    • H01L2224/01—Means for bonding being attached to, or being formed on, the surface to be connected, e.g. chip-to-package, die-attach, "first-level" interconnects; Manufacturing methods related thereto
    • H01L2224/42—Wire connectors; Manufacturing methods related thereto
    • H01L2224/47—Structure, shape, material or disposition of the wire connectors after the connecting process
    • H01L2224/48—Structure, shape, material or disposition of the wire connectors after the connecting process of an individual wire connector
    • H01L2224/484—Connecting portions
    • H01L2224/48463—Connecting portions the connecting portion on the bonding area of the semiconductor or solid-state body being a ball bond

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Description

本発明は、ＭＥＭＳ素子、特にマイクロフォン、各種センサ、スイッチ等として用いられる容量型のＭＥＭＳ素子の製造方法に関する。 The present invention, MEMS device, in particular a microphone, various sensors, relates to the production how a capacitive MEMS device which is used as a switch or the like.

従来、半導体プロセスを用いたＭＥＭＳ(Micro Electro Mechanical Systems)素子では、半導体基板上に可動電極、犠牲層及び固定電極を形成した後、犠牲層の一部を除去することで、スペーサーを介して可動電極と固定電極が固定された構造となっている。   Conventionally, in a micro electro mechanical systems (MEMS) element using a semiconductor process, a movable electrode, a sacrificial layer, and a fixed electrode are formed on a semiconductor substrate, and then a part of the sacrificial layer is removed to move through a spacer. An electrode and a fixed electrode are fixed.

例えば、容量型ＭＥＭＳ素子である音響トランスデューサーは、音圧を通過させる複数の貫通孔を備えた固定電極と、音圧を受けて振動する可動電極とを対向して配置し、振動する可動電極の変位を電極間の容量変化として検出する構成となっている。このようなＭＥＭＳ素子を用いてＭＥＭＳマイクロフォンを形成する場合、ＭＥＭＳ素子の出力信号を処理するため、信号処理機能を有する集積回路（ＩＣ）が必要となる。   For example, an acoustic transducer that is a capacitive MEMS element has a fixed electrode having a plurality of through holes that allow sound pressure to pass therethrough and a movable electrode that vibrates in response to the sound pressure and is opposed to the movable electrode that vibrates. The displacement is detected as a change in capacitance between the electrodes. When a MEMS microphone is formed using such a MEMS element, an integrated circuit (IC) having a signal processing function is required to process an output signal of the MEMS element.

例えば図９は、一般的なＭＥＭＳマイクロフォンの概略図を示し、ＭＥＭＳ素子１００およびＩＣチップ１０１が実装基板１０２に実装され、金属缶１０３で覆われた構成となっている。ＭＥＭＳ素子１００で検出された電気信号（検出信号）は、金属ワイヤ１０４を経由してＩＣチップ１０１に入力し、所望の信号処理を行い、図示しない配線を経由し実装基板１０２の接続端子から外部へ出力される。   For example, FIG. 9 shows a schematic diagram of a general MEMS microphone, in which a MEMS element 100 and an IC chip 101 are mounted on a mounting substrate 102 and covered with a metal can 103. An electrical signal (detection signal) detected by the MEMS element 100 is input to the IC chip 101 via the metal wire 104, is subjected to desired signal processing, and is externally connected from a connection terminal of the mounting substrate 102 via a wiring (not shown). Is output.

金属缶１０３は、外部からのノイズや物理的接触などからＭＥＭＳ素子１００およびＩＣチップ１０１を保護するために設けられており、外部からの音波をＭＥＭＳ素子１００に到達させるため、一部に開口が形成されている。この種のＭＥＭＳマイクロフォンは、特許文献１（図４）に開示されている。   The metal can 103 is provided to protect the MEMS element 100 and the IC chip 101 from external noise, physical contact, and the like. An opening is formed in a part of the metal can 103 in order to allow sound waves from the outside to reach the MEMS element 100. Is formed. This type of MEMS microphone is disclosed in Patent Document 1 (FIG. 4).

次に、金属ワイヤ１０４による接続構造を詳細に説明するため、図１０にＭＥＭＳ素子１００の接続構造の説明図を示す。図１０に示すようにＭＥＭＳ素子１００は、シリコン基板１上に熱酸化膜２を介して可動電極３が形成され、可動電極３上には、スペーサー４を介して固定電極５が形成されている。固定電極５には複数の貫通孔６が形成されている。一方、可動電極３にはスリット７が形成され、残留応力が調整されている。固定電極５上には、通常は窒化膜が形成されるが、図示は省略している。シリコン基板１の裏面側は、シリコン基板１の一部が除去され、バックチャンバー８を形成されている。   Next, in order to explain the connection structure by the metal wire 104 in detail, FIG. 10 shows an explanatory view of the connection structure of the MEMS element 100. As shown in FIG. 10, in the MEMS element 100, the movable electrode 3 is formed on the silicon substrate 1 via the thermal oxide film 2, and the fixed electrode 5 is formed on the movable electrode 3 via the spacer 4. . A plurality of through holes 6 are formed in the fixed electrode 5. On the other hand, a slit 7 is formed in the movable electrode 3, and the residual stress is adjusted. Although a nitride film is usually formed on the fixed electrode 5, illustration is omitted. On the back side of the silicon substrate 1, a part of the silicon substrate 1 is removed, and a back chamber 8 is formed.

このような構造のＭＥＭＳ素子１００に金属ワイヤ１０４を形成する場合、可動電極３に接続する可動電極引き出し電極９、固定電極５に接続する固定電極引き出し電極１０それぞれに、ワイヤボンディングされる。その際、ＭＥＭＳ素子１００へのボンディングの際の衝撃を緩和するため、金属ワイヤ１０４の先端を加熱、溶融してボールを形成するボールボンディング法により接続を形成するのが一般的である。図１０では図示していないが、図９に示すシリコン基板に接続する接続構造も同様である。   When the metal wire 104 is formed in the MEMS element 100 having such a structure, wire bonding is performed to each of the movable electrode lead electrode 9 connected to the movable electrode 3 and the fixed electrode lead electrode 10 connected to the fixed electrode 5. At that time, in order to alleviate the impact at the time of bonding to the MEMS element 100, the connection is generally formed by a ball bonding method in which the tip of the metal wire 104 is heated and melted to form a ball. Although not shown in FIG. 10, the connection structure connected to the silicon substrate shown in FIG. 9 is the same.

このようなボールボンディング法では、可動電極引き出し電極９と金属ワイヤ１０４との接合部、あるいは固定電極引き出し電極１０と金属ワイヤ１０４との接合部の高さが、金属ワイヤの直径を超える程度の高さ（例えば、直径５０μｍの金属ワイヤを使用した場合、１００μｍ程度の高さ）となってしまう。そのため接合部の高さが高いほど、図９で説明した金属缶１０３の高さを高くする必要があった。これは近年の電子部品の薄型化という市場要求に反してしまっていた。   In such a ball bonding method, the height of the joint between the movable electrode lead electrode 9 and the metal wire 104 or the joint between the fixed electrode lead electrode 10 and the metal wire 104 exceeds the diameter of the metal wire. (For example, when a metal wire having a diameter of 50 μm is used, the height is about 100 μm). For this reason, the height of the metal can 103 described with reference to FIG. This was contrary to the market demand for thinner electronic components in recent years.

そこで、ＭＥＭＳ素子１００のシリコン基板１の厚さを薄くすることも考えられるが、厚さを薄くすることはバックチャンバー８の容積が減少してしまい、ＭＥＭＳ素子１００の感度低下を招き好ましくない。また金属缶１０３の高さだけを低くすることは、金属ワイヤ１０４との接触の問題があり限界があった。   Therefore, it is conceivable to reduce the thickness of the silicon substrate 1 of the MEMS element 100. However, reducing the thickness is not preferable because the volume of the back chamber 8 is reduced and the sensitivity of the MEMS element 100 is lowered. In addition, there is a limit in reducing only the height of the metal can 103 because there is a problem of contact with the metal wire 104.

特開２０１１−１０１３０４号公報JP 2011-101304 A

従来、実装基板上にＭＥＭＳ素子とその信号処理用の集積回路を実装し、金属ワイヤで接続する際、ＭＥＭＳ素子上の電極上に形成される金属ワイヤの接続部の高さが高く、金属缶の高さを低くすることができず、実装構造の薄型化が難しかった。本発明は、金属ワイヤの接続部の高さが高いボールボンディング法により接合を形成した場合でも、実装構造として薄型化が可能となるＭＥＭＳ素子の製造方法を提供することを目的とする。 Conventionally, when a MEMS element and its signal processing integrated circuit are mounted on a mounting substrate and connected with a metal wire, the height of the connecting portion of the metal wire formed on the electrode on the MEMS element is high, and the metal can Therefore, it was difficult to make the mounting structure thin. The present invention, even if the height of the connection portion of the metal wire to form a junction by high ball bonding method, and an object thereof is to provide a manufacturing how the MEMS device that thinning is possible as a mounting structure.

上記目的を達成するため、本願請求項１に係る発明は、バックチャンバーを備えた基板と、該基板上に、スペーサーを挟んで配置された可動電極および固定電極と、前記可動電極に接続する可動電極引き出し電極と、前記固定電極に接続する固定電極引き出し電極とを備えたＭＥＭＳ素子を集合基板上に複数個形成した後、スクライブラインに沿って前記集合基板を切断して個片化するＭＥＭＳ素子の製造方法において、可動電極引き出し電極形成予定領域および固定電極引き出し電極形成予定領域であって前記スクライブラインの切断領域に達する位置の前記集合基板の一部を除去して凹状部を形成する工程と、該凹状部内に、前記可動電極に接続する可動電極引き出し電極と、前記固定電極に接続する固定電極引き出し電極とを、それぞれ形成する工程と、前記スクライブラインに沿って前記集合基板を切断し、個々のＭＥＭＳ素子に個片化するとともに、前記凹状部の側壁の一部を除去して段部を形成し、該段部の表面に形成されている前記可動電極引き出し電極および前記固定電極引き出し電極を露出させる工程と、を含むことを特徴とする。 In order to achieve the above object, the invention according to claim 1 of the present application includes a substrate having a back chamber, a movable electrode and a fixed electrode arranged on the substrate with a spacer interposed therebetween, and a movable electrode connected to the movable electrode. A MEMS element comprising a plurality of MEMS elements each including an electrode lead electrode and a fixed electrode lead electrode connected to the fixed electrode on a collective substrate, and then cutting the collective substrate along a scribe line into pieces. A step of removing a part of the collective substrate at a position reaching the cutting region of the scribe line in the movable electrode lead electrode formation planned region and the fixed electrode lead electrode formation planned region and forming a concave portion in the manufacturing method of The movable electrode lead electrode connected to the movable electrode and the fixed electrode lead electrode connected to the fixed electrode are respectively disposed in the concave portion. Forming the step, cutting the collective substrate along the scribe line, and separating into individual MEMS elements, and forming a step portion by removing a part of the side wall of the concave portion, Exposing the movable electrode lead electrode and the fixed electrode lead electrode formed on the surface of the substrate .

本発明のＭＥＭＳ素子の製造方法によるＭＥＭＳ素子は、可動電極引き出し電極および固定電極引き出し電極を基板の一部を除去して形成した段部に形成することで、金属ワイヤとの接続部を従来に比べて低い位置に形成できる構造としている。本発明のＭＥＭＳ素子を用いた接続構造は、段部の深さを接続部の突出高さに合わせて適宜調整することで、接続部の突出高さを低くすることが可能となり、実装基板に実装して金属缶を被せた場合に、低背化が可能となる利点がある。特に、ワイヤボンディング法としてボールボンディング法により接続する場合にその効果が大きい。 The MEMS element according to the manufacturing method of the MEMS element of the present invention has a conventional connection portion with a metal wire by forming the movable electrode lead electrode and the fixed electrode lead electrode on the step portion formed by removing a part of the substrate. The structure can be formed at a lower position. In the connection structure using the MEMS element of the present invention, it is possible to reduce the protrusion height of the connection portion by appropriately adjusting the depth of the step portion according to the protrusion height of the connection portion. When mounted and covered with a metal can, there is an advantage that the height can be reduced. In particular, the effect is great when connecting by a ball bonding method as a wire bonding method.

また本発明のＭＥＭＳ素子の製造方法によるＭＥＭＳ素子は、可動電極引き出し電極および固定電極引き出し電極を除き、従来のＭＥＭＳ素子の形状を変える必要がなく、特にバックチャンバーの容量を変える必要がないため、感度の低下を招くことがない点で利点が大きい。 In addition, the MEMS element according to the manufacturing method of the MEMS element of the present invention does not need to change the shape of the conventional MEMS element except for the movable electrode lead electrode and the fixed electrode lead electrode, and particularly does not need to change the capacity of the back chamber. The advantage is great in that the sensitivity is not lowered.

本発明のＭＥＭＳ素子の製造方法は、通常のＭＥＭＳ素子の製造工程において、可動電極引き出し電極および固定電極引き出し電極の形成予定領域であって、スクライブラインンに達する位置に凹状部を形成する工程を追加することと、スクライブラインに沿った切断を行う際に、凹状部に達する位置で切断することで、可動電極引き出し電極および固定電極引き出し電極が段部に露出するように形成することができ、簡便な製造方法である。また通常のＭＥＭＳ素子の製造工程に使用される工程のみで構成できるため、歩留まりよく製造することが可能となる。   The method for manufacturing a MEMS device according to the present invention includes a step of forming a concave portion in a region where a movable electrode lead electrode and a fixed electrode lead electrode are to be formed and reaching a scribe line in a normal MEMS device manufacturing process. When adding and cutting along the scribe line, by cutting at the position reaching the concave portion, the movable electrode lead electrode and the fixed electrode lead electrode can be formed to be exposed to the stepped portion, It is a simple manufacturing method. Moreover, since it can comprise only the process used for the manufacturing process of a normal MEMS element, it becomes possible to manufacture with a sufficient yield.

本発明のＭＥＭＳ素子の製造方法によるＭＥＭＳ素子の接続構造は、可動電極引き出し電極および固定電極引き出し電極が段部に露出しているので、通常のワイヤボンディング装置を用いたボンディング方法、具体的にはキャピラリで金属ワイヤを押圧して接続を形成する方法を用いても、キャピラリが段部に残る側壁部に接触することなく接続を形成することができる。 In the MEMS element connection structure according to the MEMS element manufacturing method of the present invention, since the movable electrode lead electrode and the fixed electrode lead electrode are exposed at the step portion, a bonding method using a normal wire bonding apparatus, specifically, Even if a method of forming a connection by pressing a metal wire with a capillary is used, the connection can be formed without the capillary contacting the side wall portion remaining on the stepped portion.

本発明のＭＥＭＳ素子の製造工程の説明図である。It is explanatory drawing of the manufacturing process of the MEMS element of this invention. 本発明のＭＥＭＳ素子の製造工程の説明図である。It is explanatory drawing of the manufacturing process of the MEMS element of this invention. 本発明のＭＥＭＳ素子の製造工程の説明図である。It is explanatory drawing of the manufacturing process of the MEMS element of this invention. 本発明のＭＥＭＳ素子の製造工程の説明図である。It is explanatory drawing of the manufacturing process of the MEMS element of this invention. 本発明のＭＥＭＳ素子の製造工程の説明図である。It is explanatory drawing of the manufacturing process of the MEMS element of this invention. 本発明のＭＥＭＳ素子の製造工程の説明図である。It is explanatory drawing of the manufacturing process of the MEMS element of this invention. 本発明のＭＥＭＳ素子の製造工程の説明図である。It is explanatory drawing of the manufacturing process of the MEMS element of this invention. 本発明のＭＥＭＳ素子の製造工程による別のＭＥＭＳ素子の説明図である。It is explanatory drawing of another MEMS element by the manufacturing process of the MEMS element of this invention. 一般的なＭＥＭＳマイクロフォンの概略図である。It is the schematic of a common MEMS microphone. 従来のＭＥＭＳ素子の接続構造の説明図である。It is explanatory drawing of the connection structure of the conventional MEMS element.

本発明のＭＥＭＳ素子の製造方法によるＭＥＭＳ素子は、金属ワイヤと接続する引き出し電極の高さを低く形成している。以下、本発明のＭＥＭＳ素子の製造方法によるＭＥＭＳ素子についてその製造工程に従い詳細に説明し、次に金属ワイヤと引き出し電極の接続構造について説明する。 In the MEMS element according to the method for manufacturing a MEMS element of the present invention, the height of the extraction electrode connected to the metal wire is formed low. Hereinafter, a MEMS device according to a method for manufacturing a MEMS device of the present invention will be described in detail according to the manufacturing process, and then a connection structure between a metal wire and a lead electrode will be described.

第１の実施例としてＭＥＭＳ素子とその製造方法について説明する。ＭＥＭＳ素子は、集合基板となるシリコン基板１上に複数個同時に形成する。以下説明に使用する図面は、集合基板の一部分を図示しており、１個のＭＥＭＳ素子と隣接するＭＥＭＳ素子との間に配置されているスクライブラインの一部を含めて記載している。まず、結晶方位（１００）面の厚さ４２０μｍのシリコン基板１上に厚さ１μｍ程度の熱酸化膜２を形成し、熱酸化膜２上に、ＣＶＤ（Chemical Vapor Deposition）法により厚さ０．２〜２．０μｍ程度の導電性ポリシリコン膜を積層形成する。次に通常のフォトリソグラフ法により導電性ポリシリコン膜をパターニングし、可動電極３を形成する。可動電極３には、感度向上のためスリット８が形成されている。可動電極３上に、厚さ２．０〜５．０μｍ程度のＵＳＧ(Undoped Silicate Glass)膜からなる犠牲層１１を積層形成する。犠牲層１１上に、厚さ０．１〜１．０μｍ程度の導電性ポリシリコン膜を積層形成し、通常のフォトリソグラフ法によりパターニングし、固定電極５を形成する。犠牲層１１の一部をエッチング除去し、先に形成した可動電極３の一部を露出させる（図１）。   As a first embodiment, a MEMS device and a manufacturing method thereof will be described. A plurality of MEMS elements are simultaneously formed on the silicon substrate 1 serving as a collective substrate. In the following drawings used for explanation, a part of the collective substrate is illustrated, and a part of a scribe line arranged between one MEMS element and an adjacent MEMS element is described. First, a thermal oxide film 2 having a thickness of about 1 μm is formed on a silicon substrate 1 having a crystal orientation (100) plane of 420 μm, and a thickness of about 0 μm is formed on the thermal oxide film 2 by a CVD (Chemical Vapor Deposition) method. A conductive polysilicon film having a thickness of about 2 to 2.0 μm is stacked. Next, the conductive polysilicon film is patterned by a normal photolithography method to form the movable electrode 3. A slit 8 is formed in the movable electrode 3 to improve sensitivity. A sacrificial layer 11 made of a USG (Undoped Silicate Glass) film having a thickness of about 2.0 to 5.0 μm is stacked on the movable electrode 3. A conductive polysilicon film having a thickness of about 0.1 to 1.0 μm is laminated on the sacrificial layer 11 and patterned by a normal photolithography method to form the fixed electrode 5. A portion of the sacrificial layer 11 is removed by etching, and a portion of the previously formed movable electrode 3 is exposed (FIG. 1).

次に、可動電極引き出し電極および固定電極引き出し電極形成予定領域を開口するようにフォトレジスト１２をパターニングする。ここで開口１３は、個々のＭＥＭＳ素子に個片化する際に切断領域となるスクライブラインに達するように形成する。その後、可動電極引き出し電極および固定電極引き出し電極の形成予定領域を開口するフォトレジスト１２をエッチングマスクとして使用し、犠牲層１１、熱酸化膜２およびシリコン基板１の一部を除去し、凹状部１４を形成する（図２）。本実施例では、表面の結晶方位が（１００）のシリコン基板を用いており、凹状部１４の側壁の結晶方位が（１１１）となるような異方性エッチングを行うことで、四角柱の形状にシリコン基板1の一部が除去された凹状部１４を形成することができる。あるいは四角柱の形状に除去する代わりに、凹状部１４の側壁部が底面に向かって開口寸法が狭くなるように傾斜する結晶面を出すように異方性エッチングすることも可能である。なお、図９で説明したようにシリコン基板との接続を形成するための引き出し電極が必要な場合は、可動電極引き出し電極および固定電極引き出し電極と同様に形成すれば良い。以下、シリコン基板との接続を形成するための引き出し電極の形成方法の説明は省略する。   Next, the photoresist 12 is patterned so as to open regions where the movable electrode lead electrode and the fixed electrode lead electrode are to be formed. Here, the opening 13 is formed so as to reach a scribe line that becomes a cutting region when individual MEMS elements are separated. Thereafter, the photoresist 12 that opens the regions where the movable electrode lead electrode and the fixed electrode lead electrode are to be formed is used as an etching mask, and the sacrificial layer 11, the thermal oxide film 2, and a part of the silicon substrate 1 are removed to form the concave portion 14. (FIG. 2). In this example, a silicon substrate having a crystal orientation of (100) on the surface is used, and by performing anisotropic etching so that the crystal orientation of the sidewall of the concave portion 14 becomes (111), the shape of the quadrangular prism is obtained. The concave portion 14 from which a part of the silicon substrate 1 is removed can be formed. Alternatively, anisotropic etching may be performed so that the side wall portion of the concave portion 14 has a crystal plane that is inclined so that the opening size becomes narrower toward the bottom surface instead of being removed in the shape of a quadrangular prism. In addition, as described with reference to FIG. 9, when an extraction electrode for forming a connection with the silicon substrate is necessary, it may be formed in the same manner as the movable electrode extraction electrode and the fixed electrode extraction electrode. Hereinafter, description of the method for forming the extraction electrode for forming the connection with the silicon substrate will be omitted.

凹状部１４の深さは、この底面に後述する可動電極引き出し電極あるいは固定電極引き出し電極を形成し、これら引き出し電極と金属ワイヤの接続を形成する際に、金属ワイヤの高さが高くならない深さに適宜調整すればよい。一例として、１００μｍ程度の深さとなる凹状部１４を形成することができる。また後述するように、凹状部１４の側壁部の一部は、個片化の工程で除去するため、凹状部１４の底面の広さは、可動電極引き出し電極あるいは固定電極引き出し電極の大きさより広く形成しておくのが好ましい。   The depth of the concave portion 14 is such that a movable electrode lead electrode or a fixed electrode lead electrode, which will be described later, is formed on the bottom surface, and the height of the metal wire is not increased when the connection between the lead electrode and the metal wire is formed. May be adjusted as appropriate. As an example, the concave portion 14 having a depth of about 100 μm can be formed. Further, as will be described later, since a part of the side wall of the concave portion 14 is removed in the process of singulation, the width of the bottom surface of the concave portion 14 is wider than the size of the movable electrode extraction electrode or the fixed electrode extraction electrode. It is preferable to form it.

フォトレジスト１２を除去し、表面を絶縁膜である窒化膜１５で被覆し、通常のフォトリソグラフ法により可動電極３および固定電極５の一部を露出させる（図３）。   The photoresist 12 is removed, the surface is covered with a nitride film 15 which is an insulating film, and a part of the movable electrode 3 and the fixed electrode 5 is exposed by a normal photolithographic method (FIG. 3).

その後、通常のフォトリソグラフ法により、可動電極３および固定電極５にそれぞれ接触する可動電極引き出し電極９および固定電極引き出し電極１０を形成する。これらの引き出し電極は、図４に示すように先に形成した凹状部１４の側壁に沿って底面まで引き出される形状とする（図４）。前述のように凹状部１４は１００μｍ程度の深さであるが、通常のフォトリソグラフ法によりパターニング可能である。ここで、通常のフォトリソグラフ法により窒化膜１５と固定電極５の一部を除去し、音圧を可動電極３に伝えるための貫通孔６を形成し、貫通孔６内に犠牲層１１を露出させる。   Thereafter, the movable electrode lead electrode 9 and the fixed electrode lead electrode 10 that are in contact with the movable electrode 3 and the fixed electrode 5 are formed by a normal photolithography method. These lead electrodes are formed so as to be drawn to the bottom surface along the side wall of the concave portion 14 formed earlier as shown in FIG. 4 (FIG. 4). As described above, the concave portion 14 has a depth of about 100 μm, but can be patterned by an ordinary photolithographic method. Here, the nitride film 15 and a part of the fixed electrode 5 are removed by a normal photolithographic method, a through hole 6 for transmitting sound pressure to the movable electrode 3 is formed, and the sacrificial layer 11 is exposed in the through hole 6. Let

その後、シリコン基板１の裏面側から熱酸化膜２が露出するまでシリコン基板１の一部を除去し、バックチャンバー８を形成する。その後、貫通孔６を通して犠牲層１１の一部を除去してスペーサー４を形成する。その結果、スペーサー４に可動電極３と固定電極５が固定された中空構造が形成される。この犠牲層１１のエッチングにより、熱酸化膜２の一部も除去される（図５）。   Thereafter, part of the silicon substrate 1 is removed from the back side of the silicon substrate 1 until the thermal oxide film 2 is exposed, and a back chamber 8 is formed. Thereafter, a part of the sacrificial layer 11 is removed through the through hole 6 to form the spacer 4. As a result, a hollow structure in which the movable electrode 3 and the fixed electrode 5 are fixed to the spacer 4 is formed. By etching the sacrificial layer 11, a part of the thermal oxide film 2 is also removed (FIG. 5).

次に個片化を行う。本発明ではこの個片化の際、先に形成した凹状部１４の側壁部の一部をスクライブラインの切削除去と同時に除去する。その結果、凹状部の形状は角柱上に掘り込まれた形状から、ＭＥＭＳチップの側壁側に開口（露出）する形状の段部１６に可動電極引き出し電極９と固定電極引き出し電極１０が形成される（図６）。   Next, individualization is performed. In the present invention, at the time of the separation, a part of the side wall portion of the concave portion 14 formed earlier is removed simultaneously with the cutting removal of the scribe line. As a result, the movable electrode lead electrode 9 and the fixed electrode lead electrode 10 are formed on the stepped portion 16 having an opening (exposed) shape on the side wall side of the MEMS chip from the shape of the concave portion dug on the prism. (FIG. 6).

この個片化工程についてさらに説明を加えると、凹状部１４を直交するスクライブラインの両方に跨るように配置する場合、凹状部１４の側壁部の２面が個片化工程で除去され、方形のＭＥＭＳ素子の角部に、二方向に側壁部が残り、二方向が開口している段部１６内に引き出し電極が形成されることになる。また、凹状部１４が一つのスクライブラインにのみ接触するように配置する場合、凹状部１４の側壁部の１面が個片化工程で除去され、方形のＭＥＭＳ素子の一辺に、三方に側壁部が残り、1面が開口している段部１６内に引き出し電極が形成されることになる。   In further description of this individualization step, when the concave portion 14 is arranged so as to straddle both scribe lines orthogonal to each other, two surfaces of the side wall portion of the concave portion 14 are removed in the individualization step, and the rectangular shape In the corner portion of the MEMS element, a side wall portion remains in two directions, and an extraction electrode is formed in the step portion 16 opened in the two directions. Further, when the concave portion 14 is arranged so as to contact only one scribe line, one side of the side wall portion of the concave portion 14 is removed by the singulation process, and the side wall portion is formed on one side of the square MEMS element. As a result, a lead electrode is formed in the step portion 16 having one open surface.

以上のように本実施例では、従来のＭＥＭＳ素子と比較して、実装時に金属ワイヤと接続が形成される可動電極引き出し電極９と固定電極引き出し電極１０がシリコン基板１の一部を除去して形成した段部１６に延出した形状のＭＥＭＳ素子を形成することができる。   As described above, in this embodiment, compared with the conventional MEMS element, the movable electrode lead electrode 9 and the fixed electrode lead electrode 10 that are connected to the metal wire at the time of mounting remove a part of the silicon substrate 1. A MEMS element having a shape extending to the formed step portion 16 can be formed.

次に、第１の実施例で説明したＭＥＭＳ素子に対して金属ワイヤを接続する接続構造とその接続方法について説明する。第１の実施例で説明したように、可動電極引き出し電極９と固定電極引き出し電極１０は、それぞれＭＥＭＳ素子の側壁側に開口する段部１６の表面に形成されている。一般的なワイヤボンディング法によりこの段部１６内に形成された可動電極引き出し電極９および固定電極引き出し電極１０にそれぞれ金属ワイヤ１０４を接続する。ここで特に、図７に示すようにボールボンディング法により接続を形成する場合、金属ワイヤ１０４の先端を加熱、溶融してボールを形成し、このボールを各引き出し電極にキャピラリにより押圧して接触させる。その結果、金属ワイヤ１０４のボールは、完全に押しつぶされず高い接続が形成されることになる。   Next, a connection structure for connecting a metal wire to the MEMS element described in the first embodiment and a connection method thereof will be described. As described in the first embodiment, the movable electrode lead electrode 9 and the fixed electrode lead electrode 10 are respectively formed on the surface of the step portion 16 opened on the side wall side of the MEMS element. Metal wires 104 are respectively connected to the movable electrode lead electrode 9 and the fixed electrode lead electrode 10 formed in the step portion 16 by a general wire bonding method. Here, in particular, when the connection is formed by the ball bonding method as shown in FIG. 7, the tip of the metal wire 104 is heated and melted to form a ball, and this ball is pressed and brought into contact with each extraction electrode by a capillary. . As a result, the ball of the metal wire 104 is not completely crushed and a high connection is formed.

しかし本発明では図７に示すように、可動電極引き出し電極９および固定電極引き引き出し電極１０は、シリコン基板１の一部が除去された段部１６上に形成されているため、接続部に高いボールが形成されていたとしても、全体としては低い接続構造を形成することが可能となる。ワイヤボンディング法は、ボールボンディング法に限定されるものではないが、接合の高さが高いボールボンディング法で効果が大きいことがわかる。   However, in the present invention, as shown in FIG. 7, the movable electrode extraction electrode 9 and the fixed electrode extraction electrode 10 are formed on the stepped portion 16 from which a part of the silicon substrate 1 is removed. Even if the balls are formed, it is possible to form a low connection structure as a whole. The wire bonding method is not limited to the ball bonding method, but it can be seen that the ball bonding method having a high bonding height is highly effective.

このように本実施例の接続構造は、引き出し電極と金属ワイヤとの接合部の高さが相対的に低く形成できるので、ＭＥＭＳ素子を実装基板上に実装し、金属缶で覆う構造のパッケージの低背化が可能となり効果が大きい。   As described above, since the connection structure of the present embodiment can be formed with a relatively low height of the joint between the extraction electrode and the metal wire, the MEMS device is mounted on the mounting substrate and covered with a metal can. It is possible to reduce the height, which is very effective

以上本発明の実施例について説明したが、本発明はこれらに限定されるものでないことは言うまでもない。例えば、ＭＥＭＳ素子を形成するシリコン基板の表面の結晶方位を変更することで異方性エッチングにより形成される凹状部に形状を変更したり、凹状部の形成をドライエッチング法に変更し、そのエッチング条件を変更することで、凹状部の形状を変更することも可能である。例えば、可動電極引き出し電極９および固定電極引き出し電極１０が延出する側壁部の形状を図８に示すように傾斜した形状とすることが可能である。   As mentioned above, although the Example of this invention was described, it cannot be overemphasized that this invention is not limited to these. For example, by changing the crystal orientation of the surface of the silicon substrate on which the MEMS element is formed, the shape is changed to a concave portion formed by anisotropic etching, or the formation of the concave portion is changed to a dry etching method, and the etching is performed. It is also possible to change the shape of the concave portion by changing the conditions. For example, the shape of the side wall portion from which the movable electrode lead electrode 9 and the fixed electrode lead electrode 10 extend can be inclined as shown in FIG.

１：シリコン基板、２：熱酸化膜、３：可動電極、４：スペーサー、５：固定電極膜、６：貫通孔、７：スリット、８：バックチャンバー、９：可動電極引き出し電極、１０：固定電極引き出し電極、１１：犠牲層、１２：フォトレジスト、１３：開口、１４：凹状部、１５：窒化膜、１６：段部 1: silicon substrate, 2: thermal oxide film, 3: movable electrode, 4: spacer, 5: fixed electrode film, 6: through-hole, 7: slit, 8: back chamber, 9: movable electrode lead electrode, 10: fixed Electrode extraction electrode, 11: sacrificial layer, 12: photoresist, 13: opening, 14: concave portion, 15: nitride film, 16: stepped portion

Claims (1)

バックチャンバーを備えた基板と、該基板上に、スペーサーを挟んで配置された可動電極および固定電極と、前記可動電極に接続する可動電極引き出し電極と、前記固定電極に接続する固定電極引き出し電極とを備えたＭＥＭＳ素子を集合基板上に複数個形成した後、スクライブラインに沿って前記集合基板を切断して個片化するＭＥＭＳ素子の製造方法において、
可動電極引き出し電極形成予定領域および固定電極引き出し電極形成予定領域であって前記スクライブラインの切断領域に達する位置の前記集合基板の一部を除去して凹状部を形成する工程と、
該凹状部内に、前記可動電極に接続する可動電極引き出し電極と、前記固定電極に接続する固定電極引き出し電極とを、それぞれ形成する工程と、
前記スクライブラインに沿って前記集合基板を切断し、個々のＭＥＭＳ素子に個片化するとともに、前記凹状部の側壁の一部を除去して段部を形成し、該段部の表面に形成されている前記可動電極引き出し電極および前記固定電極引き出し電極を露出させる工程と、を含むことを特徴とするＭＥＭＳ素子の製造方法。 A substrate provided with a back chamber; a movable electrode and a fixed electrode disposed on the substrate with a spacer interposed therebetween; a movable electrode extraction electrode connected to the movable electrode; and a fixed electrode extraction electrode connected to the fixed electrode; In a method for manufacturing a MEMS device, the method includes: forming a plurality of MEMS elements on a collective substrate; and cutting the collective substrate along a scribe line into pieces.
Removing a part of the collective substrate at a position reaching the cutting region of the scribe line in the movable electrode lead electrode formation planned region and the fixed electrode lead electrode formation planned region, and forming a concave portion;
Forming a movable electrode lead electrode connected to the movable electrode and a fixed electrode lead electrode connected to the fixed electrode, respectively, in the concave portion;
The collective substrate is cut along the scribe line and separated into individual MEMS elements, and a step portion is formed by removing a part of the side wall of the concave portion, and is formed on the surface of the step portion. Exposing the movable electrode lead electrode and the fixed electrode lead electrode. A method of manufacturing a MEMS device, comprising:
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