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JP2007294872A - High voltage lateral MOSFET - Google Patents

High voltage lateral MOSFET Download PDF

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JP2007294872A
JP2007294872A JP2007031950A JP2007031950A JP2007294872A JP 2007294872 A JP2007294872 A JP 2007294872A JP 2007031950 A JP2007031950 A JP 2007031950A JP 2007031950 A JP2007031950 A JP 2007031950A JP 2007294872 A JP2007294872 A JP 2007294872A
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insulating film
gate
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electrode
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JP5332112B2 (en
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Tomokazu Mizushima
智教 水島
Hitoshi Sumida
仁志 澄田
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Fuji Electric Co Ltd
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    • HELECTRICITY
    • H10SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10DINORGANIC ELECTRIC SEMICONDUCTOR DEVICES
    • H10D30/00Field-effect transistors [FET]
    • H10D30/60Insulated-gate field-effect transistors [IGFET]
    • H10D30/64Double-diffused metal-oxide semiconductor [DMOS] FETs
    • H10D30/65Lateral DMOS [LDMOS] FETs
    • HELECTRICITY
    • H10SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10DINORGANIC ELECTRIC SEMICONDUCTOR DEVICES
    • H10D62/00Semiconductor bodies, or regions thereof, of devices having potential barriers
    • H10D62/10Shapes, relative sizes or dispositions of the regions of the semiconductor bodies; Shapes of the semiconductor bodies
    • H10D62/124Shapes, relative sizes or dispositions of the regions of semiconductor bodies or of junctions between the regions
    • H10D62/126Top-view geometrical layouts of the regions or the junctions
    • HELECTRICITY
    • H10SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10DINORGANIC ELECTRIC SEMICONDUCTOR DEVICES
    • H10D62/00Semiconductor bodies, or regions thereof, of devices having potential barriers
    • H10D62/10Shapes, relative sizes or dispositions of the regions of the semiconductor bodies; Shapes of the semiconductor bodies
    • H10D62/13Semiconductor regions connected to electrodes carrying current to be rectified, amplified or switched, e.g. source or drain regions
    • H10D62/149Source or drain regions of field-effect devices
    • H10D62/151Source or drain regions of field-effect devices of IGFETs 
    • H10D62/152Source regions of DMOS transistors
    • HELECTRICITY
    • H10SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10DINORGANIC ELECTRIC SEMICONDUCTOR DEVICES
    • H10D64/00Electrodes of devices having potential barriers
    • H10D64/20Electrodes characterised by their shapes, relative sizes or dispositions 
    • H10D64/27Electrodes not carrying the current to be rectified, amplified, oscillated or switched, e.g. gates
    • H10D64/311Gate electrodes for field-effect devices
    • H10D64/411Gate electrodes for field-effect devices for FETs
    • H10D64/511Gate electrodes for field-effect devices for FETs for IGFETs
    • H10D64/514Gate electrodes for field-effect devices for FETs for IGFETs characterised by the insulating layers
    • H10D64/516Gate electrodes for field-effect devices for FETs for IGFETs characterised by the insulating layers the thicknesses being non-uniform

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Abstract

【目的】直線状のセルを有する半導体装置において、端部の曲率部分でのオン耐圧を向上させることができる高耐圧横型MOSFETを提供すること。
【解決手段】n型半導体基板1の表面層に離してnウェル領域4とp型オフセット領域2を形成し、n型ウェル領域4の表面層にp型ソース領域5とn型コンタクト領域6を形成し、p型オフセット領域2の表面層にp型ドレイン領域3を形成し、n型ウェル領域4上とn型半導体基板1上に第1ゲート酸化膜7を形成し、この第1ゲート酸化膜7と接してp型オフセット領域2上にLOCOS8を形成し、第1ゲート酸化膜7上にゲート電極10を形成する。曲率部分のn型ウェル領域4上までを第1ゲート酸化膜7より厚い第2ゲート酸化膜(LOCOS8)で被覆することでn型ウェル領域5の表面の電界集中を緩和することができてオン耐圧の向上を図ることができる。
【選択図】 図1
An object of the present invention is to provide a high breakdown voltage lateral MOSFET capable of improving an on breakdown voltage at a curvature portion at an end in a semiconductor device having a linear cell.
An n well region and a p type offset region are formed apart from a surface layer of an n type semiconductor substrate, and a p type source region and an n type contact region are formed on the surface layer of the n type well region. The p-type drain region 3 is formed on the surface layer of the p-type offset region 2, the first gate oxide film 7 is formed on the n-type well region 4 and the n-type semiconductor substrate 1, and this first gate oxidation is performed. A LOCOS 8 is formed on the p-type offset region 2 in contact with the film 7, and a gate electrode 10 is formed on the first gate oxide film 7. By covering the n-type well region 4 at the curvature portion with the second gate oxide film (LOCOS 8) thicker than the first gate oxide film 7, the electric field concentration on the surface of the n-type well region 5 can be relaxed and turned on. The breakdown voltage can be improved.
[Selection] Figure 1

Description

この発明は、半導体基板上に形成された高耐圧横型MOSFETに関する。   The present invention relates to a high breakdown voltage lateral MOSFET formed on a semiconductor substrate.

近年、横型IGBT(IGBT:絶縁ゲート型バイポーラトランジスタ)などの高耐圧デバイスとその駆動・制御・保護回路を一つのシリコン基板上に集積したパワーIC(IC:集積回路)の開発が盛んになっている。特に、SOI(Silicon On Insulator)基板とトレンチ分離を組み合わせた誘電体分離技術の進歩により、バイポーラデバイスのハイサイドスイッチへの適用とその他の出力回路構成が可能となり、パワーICの適用分野が大幅に拡がった。現在では横型IGBTで構成されたトーテムポール回路を1チップ上に複数搭載したモータ駆動用ICやディスプレイ駆動用ICが誘電体分離技術を用いて実現されている。   In recent years, development of power ICs (ICs: integrated circuits) in which high-voltage devices such as lateral IGBTs (IGBTs: insulated gate bipolar transistors) and their drive / control / protection circuits are integrated on a single silicon substrate has become active. Yes. In particular, the progress of dielectric isolation technology combining SOI (Silicon On Insulator) substrate and trench isolation enables the application of bipolar devices to high-side switches and other output circuit configurations, greatly expanding the application fields of power ICs. Spread. At present, motor driving ICs and display driving ICs in which a plurality of totem pole circuits composed of lateral IGBTs are mounted on one chip are realized by using dielectric separation technology.

ハイサイドスイッチを駆動する場合、レベルシフト回路が必要になる。このレベルシフト回路を高耐圧pチャネル形MOSFET(以下、HVPMOSと略す)で構成することにより別電源やコンデンサなどを必要としないシンプルなレベルシフト回路を構成することができる。しかも、HVPMOSのゲート酸化膜を厚くする事により、HVPMOSを出力用電源電圧によって直接駆動することが可能となり、nチャネル形MOSFETと組み合わせたCMOS(Complimentary MOS)構成のレベルシフト回路を実現できる。その結果、レベルシフト回路の低消費電力化を達成することができる。   When driving the high side switch, a level shift circuit is required. By configuring this level shift circuit with a high voltage p-channel MOSFET (hereinafter abbreviated as HVPMOS), a simple level shift circuit that does not require a separate power source or capacitor can be configured. In addition, by increasing the thickness of the HVPMOS gate oxide film, the HVPMOS can be directly driven by the output power supply voltage, and a level shift circuit of a CMOS (Complementary MOS) structure combined with an n-channel MOSFET can be realized. As a result, low power consumption of the level shift circuit can be achieved.

このような背景から、入力側電源電圧が印加される標準のゲート酸化膜とは異なり、出力側電源電圧の印加に耐えうる厚膜のゲート酸化膜を備えたHVPMOSの開発が重要になっている。そしてデバイス構造は、パワーICへの搭載を可能とする横型構造であることが必須となる。
なお、本明細書では標準膜厚のゲート酸化膜を備えたHVPMOSを標準ゲートHVPMOSと呼び、厚膜のゲート酸化膜を備えたHVPMOSを厚膜ゲートHVPMOSと呼ぶ。
Against this background, it is important to develop an HVPMOS having a thick gate oxide film that can withstand the application of the output side power supply voltage, unlike the standard gate oxide film to which the input side power supply voltage is applied. . The device structure must be a horizontal structure that can be mounted on a power IC.
In this specification, an HVPMOS having a gate oxide film having a standard thickness is called a standard gate HVPMOS, and an HVPMOS having a thick gate oxide film is called a thick gate HVPMOS.

図3は、厚膜ゲートHVPMOSを適用したレベルシフト回路の一例を示す図である。図3の回路には出力回路部Aとして二つのIGBT(N1,N2)からなるトーテムポール回路が搭載され、その前段に二つのnチャネルMOSFET(N3,N4)と二つの厚膜ゲートHVPMOS(P1,P2)で構成されたレベルシフト回路部Bが搭載されている。出力デバイスN1はゲート信号Vin1によって制御され、N2はレベルシフト回路を駆動するゲート信号Vin2とゲート信号Vin3によって制御される。なお、出力回路部Aに内蔵されたZD(ツェナーダイオード)はN2のゲートを保護するためである。出力側電源電圧VHには高電圧が印加される為、本回路を構成するZD以外のデバイスは全て高耐圧デバイスである。   FIG. 3 is a diagram showing an example of a level shift circuit to which the thick gate HVPMOS is applied. In the circuit of FIG. 3, a totem pole circuit composed of two IGBTs (N1, N2) is mounted as an output circuit section A, and two n-channel MOSFETs (N3, N4) and two thick film gates HVPMOS (P1) are provided in the preceding stage. , P2) is mounted. The output device N1 is controlled by the gate signal Vin1, and N2 is controlled by the gate signal Vin2 and the gate signal Vin3 that drive the level shift circuit. The ZD (Zener diode) built in the output circuit section A is for protecting the gate of N2. Since a high voltage is applied to the output side power supply voltage VH, all the devices other than ZD constituting this circuit are high withstand voltage devices.

本回路のレベルシフト回路Bは既知の回路であり、ここではその動作説明は省く。このレベルシフト回路の特徴はP1とP2のゲートを出力側電源電圧VHで駆動できるところにある。このため、レベルシフト回路を一般的なCMOS回路で構成することが可能となり、レベルシフト回路の消費電力を大幅に低減させることができる。
図4は、従来の厚膜ゲートHVPMOSの構成図であり、同図(a)は要部平面図、同図(b)は同図(a)のX−X線で切断した要部断面図、同図(c)は同図(a)のY−Y線で切断した要部断面図である。この図では素子が形成されるn型半導体基板1はパワーICの出力回路を構成するnチャネル型素子の形成を容易にする目的から選んでいる。なお、このn型半導体基板1は、パワーICの用途に応じてCZ基板や接合分離基板、あるいはSOI基板などが選択される。
The level shift circuit B of this circuit is a known circuit, and the description of its operation is omitted here. This level shift circuit is characterized in that the gates of P1 and P2 can be driven by the output side power supply voltage VH. For this reason, the level shift circuit can be constituted by a general CMOS circuit, and the power consumption of the level shift circuit can be greatly reduced.
4A and 4B are configuration diagrams of a conventional thick film gate HVPMOS, where FIG. 4A is a plan view of the main part, and FIG. 4B is a cross-sectional view of the main part taken along line XX of FIG. FIG. 10C is a cross-sectional view of the main part taken along line YY of FIG. In this figure, the n-type semiconductor substrate 1 on which the element is formed is selected for the purpose of facilitating the formation of the n-channel type element constituting the output circuit of the power IC. As the n-type semiconductor substrate 1, a CZ substrate, a junction separation substrate, an SOI substrate, or the like is selected according to the application of the power IC.

図4に示した従来の厚膜ゲートHVPMOSについて説明する。尚、図中の1はn型半導体基板、2はp型オフセット領域、3はp型ドレイン領域、4はn型ウェル領域、5はp型ソース領域、6はn型コンタクト領域、7はゲート酸化膜、8はLOCOS、9はソース電極、10はゲート電極、11はドレイン電極、Sはソース端子、Gはゲート端子およびDはドレイン端子である。   The conventional thick film gate HVPMOS shown in FIG. 4 will be described. In the figure, 1 is an n-type semiconductor substrate, 2 is a p-type offset region, 3 is a p-type drain region, 4 is an n-type well region, 5 is a p-type source region, 6 is an n-type contact region, and 7 is a gate. An oxide film, 8 is LOCOS, 9 is a source electrode, 10 is a gate electrode, 11 is a drain electrode, S is a source terminal, G is a gate terminal, and D is a drain terminal.

n型半導体基板1(n型ドリフト領域)にHVPMOSを形成するためには、p型オフセット領域2が不可欠となる。素子耐圧はこのp型オフセット領域2とnドリフト領域1の接合で発生するアバランシェブレークダウン電圧によって決まり、この電圧はp型オフセット領域2の形成条件に依存する。従って、素子の高耐圧化はこのp型オフセット領域2の形成条件を最適化することで実施される。また、図4(a)に示す平面パタンーンにおいて、曲率部分にp型ソース領域5を形成すると、このp型ソース領域5からp型ドレイン領域3に向って流れる電流がp型ドレイン領域3で電流集中を起こして素子を劣化させることがある。これを防止するために曲率部分にはp型ソース領域5は形成されていない。   In order to form an HVPMOS on the n-type semiconductor substrate 1 (n-type drift region), the p-type offset region 2 is indispensable. The element breakdown voltage is determined by an avalanche breakdown voltage generated at the junction of the p-type offset region 2 and the n drift region 1, and this voltage depends on the formation conditions of the p-type offset region 2. Therefore, the breakdown voltage of the element is increased by optimizing the formation conditions of the p-type offset region 2. 4A, when the p-type source region 5 is formed in the curvature portion, a current flowing from the p-type source region 5 toward the p-type drain region 3 becomes a current in the p-type drain region 3. Concentration may cause deterioration of the device. In order to prevent this, the p-type source region 5 is not formed in the curvature portion.

厚膜ゲートHVPMOSと標準ゲートHVPMOSの構造上の相違点は、(1)ゲート酸化膜7の厚さと、(2)p型ソース領域5の形成工程にある。厚膜のゲート酸化膜7の厚さは図3に示す出力側電源電圧VHによって決まる。(2)に関しては本発明と関係ないためここでは説明は省略する。
厚膜ゲートHVPMOSにおいて、最も厳しい電圧印加状態となるのが、ゲート・ソース間とドレイン・ソース間に出力側電源電圧が印加される時である。即ち、図3のP2において、N4がオンしてP2のゲート電位がGND電位となり、N1がオンして出力端子VoutがGND電位になった時である。この厳しい電圧印加状態になると直線部分に比べ曲率部分では電界が集中し易くなり、ゲート電極10直下の図5で示すA部に電界集中が生じ、この電界集中によるオン状態の耐圧(以下、オン耐圧と略す)低下が起こる。すなわち、厚膜ゲートHVPMOSにおいてはオフ耐圧を確保するだけではなく、ゲート電極10とソース電極7の間に出力側電源電圧を印加した場合のオン耐圧も確保する必要がある。
図5は、厚膜ゲートHVPMOSがブレークダウンする電圧での等電位線を示した図である。ゲート電極10とn型ウェル領域4に挟まれたゲート酸化膜7はその膜厚が薄いために、A部のn型ウェル領域4の表面で電界集中が起こる。
The structural differences between the thick film gate HVPMOS and the standard gate HVPMOS are in (1) the thickness of the gate oxide film 7 and (2) the process of forming the p-type source region 5. The thickness of the thick gate oxide film 7 is determined by the output-side power supply voltage VH shown in FIG. Since (2) is not related to the present invention, the description thereof is omitted here.
In the thick gate HVPMOS, the most severe voltage application state occurs when the output side power supply voltage is applied between the gate and source and between the drain and source. That is, in P2 of FIG. 3, when N4 is turned on, the gate potential of P2 becomes the GND potential, and when N1 is turned on and the output terminal Vout becomes the GND potential. In this severe voltage application state, the electric field is more likely to be concentrated in the curvature portion than in the straight portion, and the electric field concentration is generated in the portion A shown in FIG. 5 immediately below the gate electrode 10, and the on-state breakdown voltage (hereinafter referred to as on-state) due to this electric field concentration. Decline occurs. That is, in the thick gate HVPMOS, it is necessary not only to ensure the off breakdown voltage, but also to ensure the on breakdown voltage when the output side power supply voltage is applied between the gate electrode 10 and the source electrode 7.
FIG. 5 is a diagram showing equipotential lines at a voltage at which the thick film gate HVPMOS breaks down. Since the gate oxide film 7 sandwiched between the gate electrode 10 and the n-type well region 4 is thin, electric field concentration occurs on the surface of the n-type well region 4 in the A portion.

特許文献1ならびに特許文献2にはSOI基板上の横型HVPMOSに関し、その高耐圧化の手法が述べられているが、両文献ともにオフ耐圧のことのみにしか言及されておらず、厚膜ゲートHVPMOSのゲート電極にソース電極を基準として高電圧を印加したときのオン耐圧向上に関してはなんら記載されていない。
また、特許文献3にはSOI基板上の横型HVPMOSに関し、ゲート電極にソース電極を基準として高電圧を印加したときのオン耐圧向上に関して述べられているが、HVPMOSにおけるコーナー部での電界集中における耐圧劣化に対する方策に関してはなんら記載されていない。
特開平11−145462号公報 特開2000−252467号公報 特開2005−150617号公報
Patent Document 1 and Patent Document 2 describe a method for increasing the breakdown voltage of a lateral HVPMOS on an SOI substrate, but both documents only mention the off breakdown voltage, and the thick film gate HVPMOS No mention is made of improving the on-breakdown voltage when a high voltage is applied to the gate electrode with reference to the source electrode.
Patent Document 3 describes the lateral HVPMOS on the SOI substrate with respect to improving the on breakdown voltage when a high voltage is applied to the gate electrode with reference to the source electrode. However, the breakdown voltage in the electric field concentration at the corner of the HVPMOS is described. There is no mention of measures against degradation.
JP-A-11-145462 JP 2000-252467 A JP 2005-150617 A

前記したように、厚膜ゲートHVPMOSではゲート電極10とソース電極9の間に最大で出力側電源電圧が印加される。その為、ドレイン電極11とソース電極9の間およびゲート電極10とソース電極9の間に出力側電源電圧を印加した状態が発生することになり、この印加状態でのオン耐圧を検討する必要がある。
ソース電極9に対しドレイン電極11のみに負の高電圧を印加した場合ではp型オフセット領域2とn型ドリフト領域(n型半導体基板1)の接合で高電界が発生する。しかし、図5に示したように、ゲート電極10にも負の高電圧を印加した場合にはゲート電極10直下のn型ウェル領域の表面に高電界が発生することとなる。そして、これが素子のオン耐圧の低下を招き、オフ耐圧よりもオン耐圧が低下するという問題が発生する。
As described above, in the thick film gate HVPMOS, the output side power supply voltage is applied between the gate electrode 10 and the source electrode 9 at the maximum. Therefore, a state in which the output-side power supply voltage is applied between the drain electrode 11 and the source electrode 9 and between the gate electrode 10 and the source electrode 9 occurs, and it is necessary to examine the on-breakdown voltage in this applied state. is there.
When a negative high voltage is applied only to the drain electrode 11 with respect to the source electrode 9, a high electric field is generated at the junction of the p-type offset region 2 and the n-type drift region (n-type semiconductor substrate 1). However, as shown in FIG. 5, when a negative high voltage is applied also to the gate electrode 10, a high electric field is generated on the surface of the n-type well region immediately below the gate electrode 10. This causes a decrease in the on-withstand voltage of the device, and a problem arises that the on-withstand voltage is lower than the off-withstand voltage.

よって、厚膜ゲートHVPMOSにおいてはオフ状態時のみだけではなく、ゲート電極10とソース電極9の間に出力側電源電圧を印加した場合のオン耐圧特性も確保しなければならないという課題がある。
また、パワーICに集積される厚膜ゲートHVPMOSにおいては、ドレイン電極11とソース電極9の間に高電圧が印加される。その場合でもn型半導体基板1に形成される他デバイス(制御回路や保護回路を構成するデバイス)が高電圧の影響を受けないようにする必要があり、通常、出力側電源電圧に固定されるソース電極9が接続するソース領域5で、電位が変動するドレイン電極11が接続するドレイン領域3を取り囲むパターンになっている。しかし、このようなパターンでは、コーナー部の曲率部分では直線部分より電界集中が起こり厚膜ゲートHVPMOSのオン耐圧が低下する。そのため、曲率部分でのオン耐圧の低下をいかに防ぐかが課題となる。
Therefore, in the thick gate HVPMOS, there is a problem that not only the off-state but also the on-breakdown voltage characteristic when the output side power supply voltage is applied between the gate electrode 10 and the source electrode 9 must be secured.
In the thick film gate HVPMOS integrated in the power IC, a high voltage is applied between the drain electrode 11 and the source electrode 9. Even in such a case, it is necessary to prevent other devices (devices constituting the control circuit and the protection circuit) formed on the n-type semiconductor substrate 1 from being affected by a high voltage, and are usually fixed to the output side power supply voltage. The source region 5 to which the source electrode 9 is connected has a pattern surrounding the drain region 3 to which the drain electrode 11 whose potential varies varies. However, in such a pattern, the electric field concentration occurs in the curvature portion of the corner portion than in the straight portion, and the on-breakdown voltage of the thick film gate HVPMOS decreases. Therefore, how to prevent a decrease in the ON breakdown voltage at the curvature portion is a problem.

図6は、ゲート電極とソース電極の間(Vgs)に170V印加したときの従来の厚膜ゲートHVPMOSのI−V曲線である。ソース端子Sの電位をドレイン端子Dに対して上昇させると、140Vでブレークダウンが発生し、本素子の目標オン耐圧の170Vを確保できない。このときの劣化箇所は図5(a)のA部であり曲率部分である。
この発明の目的は、前記の課題を解決して、曲率部分でのオン耐圧を向上させることができる高耐圧横型MOSFETを提供することにある。
FIG. 6 is an IV curve of a conventional thick film gate HVPMOS when 170 V is applied between the gate electrode and the source electrode (Vgs). When the potential of the source terminal S is raised with respect to the drain terminal D, breakdown occurs at 140 V, and 170 V of the target ON breakdown voltage of this element cannot be secured. The deteriorated portion at this time is a portion A in FIG. 5A and a curvature portion.
An object of the present invention is to provide a high breakdown voltage lateral MOSFET that solves the above-described problems and can improve the on breakdown voltage at the curvature portion.

前記の目的を達成するために、ドレイン電極とソース電極とが平行に形成された直線部分とドレイン電極をソース電極が取り囲む曲率部分とを備え、前記ドレイン電極と前記ソース電極との間にゲート電極が配置された平面パターンを有する横型MOSFETにおいて、前記直線部分の前記ゲート電極下に位置する第1ゲート絶縁膜の厚さより前記曲率部分の前記ゲート電極下の第2ゲート絶縁膜の方が厚い構成。   In order to achieve the above-mentioned object, a gate electrode is provided between the drain electrode and the source electrode, comprising a straight line portion in which the drain electrode and the source electrode are formed in parallel and a curvature portion surrounding the drain electrode by the source electrode. In the lateral MOSFET having a planar pattern in which the second gate insulating film under the gate electrode in the curvature portion is thicker than the thickness of the first gate insulating film located under the gate electrode in the straight portion. .

また、前記直線部分は、第1導電型の半導体層の表面層に選択的に形成された第1導電型のウェル領域と、前記半導体層の表面層に前記ウェル領域から離して選択的に形成された第2導電型のオフセット領域と、前記ウェル領域の表面層に選択的に形成された第2導電型のソース領域と、前記オフセット領域の表面層に選択的に形成された第2導電型のドレイン領域と、前記ウェル領域の表面層に選択的に形成された第1導電型のコンタクト領域と、前記ソース領域と前記オフセット領域に挟まれた前記半導体層上と前記ウェル領域上に前記第2ゲート絶縁膜を介して形成されたゲート電極と、前記第1ゲート絶縁膜と接し前記オフセット領域上を覆う前記第2ゲート絶縁膜より厚い第1フィールド絶縁膜とを備え、前記ドレイン電極が前記ドレイン領域と接し、前記ソース電極が前記ソース領域と前記コンタクト領域と接し、
前記曲率部分は、前記ウェル領域と、前記オフセット領域と、前記ドレイン領域と、前記コンタクト領域と、前記ウェル領域の上から前記オフセット領域上に亘って形成される前記第2ゲート絶縁膜を介して形成された前記ゲート電極と、前記第2ゲート絶縁膜と接し前記オフセット領域上を覆う前記第1フィールド絶縁膜と同じ厚さの第2フィールド絶縁膜とを備え、前記ドレイン電極が前記ドレイン領域と接し、前記ソース電極が前記コンタクト領域と接する構成とする。
The straight portion is selectively formed on the surface layer of the first conductivity type semiconductor layer and the first conductivity type well region selectively formed on the surface layer of the first conductivity type semiconductor layer and separated from the well region on the surface layer of the semiconductor layer. The second conductivity type offset region formed, the second conductivity type source region selectively formed in the surface layer of the well region, and the second conductivity type selectively formed in the surface layer of the offset region The first conductivity type contact region selectively formed on the surface layer of the well region, the semiconductor layer sandwiched between the source region and the offset region, and the well region on the well region. A gate electrode formed via a two-gate insulating film; and a first field insulating film that is in contact with the first gate insulating film and covers the offset region and is thicker than the second gate insulating film; Contact with rain region, the source electrode is in contact with the source region and the contact region,
The curvature portion includes the well region, the offset region, the drain region, the contact region, and the second gate insulating film formed from above the well region to the offset region. The gate electrode formed, and a second field insulating film having the same thickness as the first field insulating film in contact with the second gate insulating film and covering the offset region, wherein the drain electrode is connected to the drain region. The source electrode is in contact with the contact region.

また、前記第2フィールド絶縁膜と前記第2ゲート絶縁膜とが同じ厚さであるとよい。
また、前記第1フィールド絶縁膜、前記第2フィールド絶縁膜および前記第2ゲート絶縁膜が1つのLOCOS(選択酸化膜)であるとよい。
また、ドレイン電極とソース電極とが平行に形成された直線部分とドレイン電極をソース電極が取り囲む曲率部分とを備え、前記ドレイン電極と前記ソース電極との間にゲート電極が配置された平面パターンを有する横型MOSFETにおいて、前記ゲート電極が前記直線部分のみに形成される構成とする。
The second field insulating film and the second gate insulating film may have the same thickness.
The first field insulating film, the second field insulating film, and the second gate insulating film may be one LOCOS (selective oxide film).
A planar pattern in which a straight line portion in which the drain electrode and the source electrode are formed in parallel and a curved portion in which the source electrode surrounds the drain electrode, and the gate electrode is disposed between the drain electrode and the source electrode; In the lateral MOSFET, the gate electrode is formed only in the straight portion.

また、前記直線部分は、第1導電型の半導体層の表面層に選択的に形成された第1導電型のウェル領域と、前記半導体層の表面層に前記ウェル領域から離して選択的に形成された第2導電型のオフセット領域と、前記ウェル領域の表面層に選択的に形成された第2導電型のソース領域と、前記オフセット領域の表面層に選択的に形成された第2導電型のドレイン領域と、前記ウェル領域の表面層に選択的に形成された第1導電型のコンタクト領域と、前記ソース領域と前記オフセット領域に挟まれた前記半導体層上と前記ウェル領域上にゲート絶縁膜を介して形成されたゲート電極と、前記ゲート絶縁膜と接し前記オフセット領域上を覆うフィールド絶縁膜とを備え、前記ドレイン電極が前記ドレイン領域と接し、前記ソース電極が前記ソース領域と前記コンタクト領域と接し、
前記曲率部分は、前記ウェル領域と、前記オフセット領域と、前記ドレイン領域と、前記コンタクト領域と、前記ウェル領域の上から前記オフセット領域上に亘って形成されるゲート絶縁膜と、前記ゲート絶縁膜と接し前記オフセット領域上を覆うフィールド絶縁膜とを備え、前記ドレイン電極が前記ドレイン領域と接し、前記ソース電極が前記コンタクト領域と接する構成とする。
The straight portion is selectively formed on the surface layer of the first conductivity type semiconductor layer and the first conductivity type well region selectively formed on the surface layer of the first conductivity type semiconductor layer and separated from the well region on the surface layer of the semiconductor layer. The second conductivity type offset region formed, the second conductivity type source region selectively formed in the surface layer of the well region, and the second conductivity type selectively formed in the surface layer of the offset region A drain region, a contact region of a first conductivity type selectively formed on a surface layer of the well region, gate insulation on the semiconductor layer and the well region sandwiched between the source region and the offset region A gate electrode formed through a film; a field insulating film in contact with the gate insulating film and covering the offset region; the drain electrode in contact with the drain region; and the source electrode in the source electrode Region and in contact with the contact region,
The curvature portion includes the well region, the offset region, the drain region, the contact region, a gate insulating film formed over the well region and the offset region, and the gate insulating film. And a field insulating film that covers the offset region, the drain electrode is in contact with the drain region, and the source electrode is in contact with the contact region.

この発明によれば、従来形成していた曲率部分のゲート酸化膜を直線部分のゲート酸化膜より膜厚が厚い酸化膜(LOCOS)にすることで、曲率部分のゲート電極直下での電界集中を防止して高いオン耐圧を確保することができる。
また、ゲート電極を直線領域にのみに配置し、曲率部分上にはゲート電極を配置しないことで、Vgs間に高電圧が印加されても曲率部分での電界集中を回避することができる。その結果高いオン耐圧を確保することが可能となる。
According to the present invention, the gate oxide film in the curvature portion that has been conventionally formed is made an oxide film (LOCOS) thicker than the gate oxide film in the straight portion, thereby concentrating the electric field concentration directly under the gate electrode in the curvature portion. Therefore, a high on-voltage can be ensured.
In addition, by arranging the gate electrode only in the linear region and not arranging the gate electrode on the curvature portion, electric field concentration in the curvature portion can be avoided even when a high voltage is applied between Vgs. As a result, it is possible to ensure a high on-voltage.

発明の実施の形態を以下の実施例にて説明する。   Embodiments of the invention will be described in the following examples.

図1は、この発明の第1実施例の高耐圧横型MOSFETの要部構成図であり、同図(a)は平面図、同図(b)は同図(a)のX−X線で切断した断面図、同図(c)は同図(a)のY−Y線で切断した断面図である。この高耐圧横型MOSFETはHVPMOSであり、同図(a)は電極を省略した図であり、同図(b)、同図(c)は電極を示した図である。尚、図中の符号は図5と同一部位には同一の符号を付した。   1A and 1B are main part configuration diagrams of a high breakdown voltage lateral MOSFET according to a first embodiment of the present invention. FIG. 1A is a plan view, and FIG. 1B is a sectional view taken along line XX in FIG. The cut cross-sectional view and FIG. 4C are cross-sectional views taken along line YY of FIG. The high breakdown voltage lateral MOSFET is an HVPMOS. FIG. 10A is a diagram in which electrodes are omitted, and FIGS. 10B and 10C are diagrams showing electrodes. In addition, the code | symbol in a figure attached | subjected the same code | symbol to the same site | part as FIG.

n型半導体基板1の表面層に離してnウェル領域4とp型オフセット領域2を形成し、n型ウェル領域4の表面層にp型ソース領域5とn型コンタクト領域6を形成する。p型オフセット領域2の表面層にp型ドレイン領域3を形成する。n型ウェル領域4上とn型半導体基板1(n型ドリフト領域)上に第1ゲート酸化膜7を形成し、この第1ゲート酸化膜7と接してp型オフセット領域2上にLOCOS8(フィールド酸化膜)を形成し、第1ゲート酸化膜7上にゲート電極10を形成する、このゲート電極10をLOCOS8上に延在させてフィールドプレートとする。同図(a)に示す平面パターンにおいて、p型ドレイン領域3をp型オフセット領域2がp型ドレイン領域3と接して帯状に取り囲み、p型オフセット領域2をn型ウェル領域4が取り囲み(p型オフセット領域2の外端線をn型ウェル領域4の内端線が取り囲み)、n型ウェル領域4の直線部分にp型ソース領域5を形成している。そのためp型ソース領域5は曲率部分(コーナー部)には形成されていない。曲率部分にp型ソース領域5が形成されていないために曲率部分には電流は流れない。また、曲率部分には第1ゲート酸化膜7は形成されず第1ゲート酸化膜7より厚い第2ゲート酸化膜であるLOCOS8が形成されている。直線部分と曲率部分のLOCOS8の膜厚は同じで同時に形成される(これは直線部分のLOCOS8を第1酸化膜、曲線部分のLOCOS8を第2酸化膜とすると、この第1、第2酸化膜をゲート酸化膜より厚く同じ厚さで同時に形成するということである。)LOCOS8の曲率部分の幅W1は直線部分のLOCOS8の幅W2と第1ゲート酸化膜7の幅W3を合わせた幅に等しくしてある。また、直線部分と曲線部分のゲート電極10は等しくしてある。   An n well region 4 and a p type offset region 2 are formed apart from the surface layer of the n type semiconductor substrate 1, and a p type source region 5 and an n type contact region 6 are formed in the surface layer of the n type well region 4. A p-type drain region 3 is formed in the surface layer of the p-type offset region 2. A first gate oxide film 7 is formed on the n-type well region 4 and the n-type semiconductor substrate 1 (n-type drift region), and a LOCOS 8 (field) is formed on the p-type offset region 2 in contact with the first gate oxide film 7. An oxide film) is formed, and a gate electrode 10 is formed on the first gate oxide film 7. This gate electrode 10 is extended on the LOCOS 8 to form a field plate. In the planar pattern shown in FIG. 6A, the p-type drain region 3 is surrounded by a strip in contact with the p-type drain region 3 and the p-type offset region 2 is surrounded by an n-type well region 4 (p The outer end line of the type offset region 2 is surrounded by the inner end line of the n-type well region 4), and the p-type source region 5 is formed in the straight portion of the n-type well region 4. Therefore, the p-type source region 5 is not formed in the curvature portion (corner portion). Since the p-type source region 5 is not formed in the curvature portion, no current flows in the curvature portion. Further, the first gate oxide film 7 is not formed in the curvature portion, and a LOCOS 8 that is a second gate oxide film thicker than the first gate oxide film 7 is formed. The straight portion and the curvature portion of the LOCOS 8 have the same film thickness and are formed at the same time. (If the straight portion LOCOS 8 is the first oxide film and the curved portion LOCOS 8 is the second oxide film, the first and second oxide films are formed. The width W1 of the curvature portion of the LOCOS 8 is equal to the sum of the width W2 of the LOCOS 8 at the straight portion and the width W3 of the first gate oxide film 7 at the same time. It is. Further, the gate electrode 10 in the straight line part and the curved line part are made equal.

LOCOS8の厚さは約600nmであり、第1ゲート酸化膜7の厚さは200nm〜400nmである。曲率部分には第2ゲート酸化膜としてLOCOS8が形成されているため、曲率部分のゲート電極10とn型ウェル領域4の間の第2ゲート酸化膜(LOCOS8)で電圧分担する電圧が第1ゲート酸化膜の場合と比べ増大し、その結果ゲート電極7直下のn型ウェル領域4の表面領域の電界集中が緩和される。   The thickness of the LOCOS 8 is about 600 nm, and the thickness of the first gate oxide film 7 is 200 nm to 400 nm. Since the LOCOS 8 is formed as the second gate oxide film in the curvature portion, the voltage shared by the second gate oxide film (LOCOS 8) between the gate electrode 10 and the n-type well region 4 in the curvature portion is the first gate. As compared with the case of the oxide film, it increases, and as a result, the electric field concentration in the surface region of the n-type well region 4 immediately below the gate electrode 7 is relaxed.

図2は、図1の厚膜ゲートHVPMOSのI−V波形図である。横軸はドレイン・ソース間電圧(Vds)であり、縦軸はオン電流(Ids)である。
厚膜ゲートHVPMOSのゲート端子Gとドレイン端子Dを0Vとし、ソース端子Sの電位を上昇させ、オン状態でのI−V曲線である。つまりオン耐圧曲線である。前記したように、曲率部分の第1ゲート酸化膜7を第2ゲート酸化膜であるLOCOS8に替えることで、曲率部分のゲート電極10とn型ウェル領域4の間のLOCOS8で電圧分担する電圧が増大し、その結果ゲート電極7直下のn型ウェル領域4の表面領域の電界集中が緩和されるので、ソース・ドレイン間に170Vの高い電圧を印加しても、素子はブレークダウンせずに170Vの高いオン耐圧が確保され正常動作する。つまり、本発明の厚膜ゲートHVPMOSのオン耐圧は、従来の厚膜ゲートHVPMOSのオン耐圧より高くすることができる。
FIG. 2 is an IV waveform diagram of the thick film gate HVPMOS of FIG. The horizontal axis is the drain-source voltage (Vds), and the vertical axis is the on-current (Ids).
The gate terminal G and the drain terminal D of the thick film gate HVPMOS are set to 0 V, the potential of the source terminal S is increased, and the curve is an IV curve in an on state. That is, it is an ON breakdown voltage curve. As described above, by replacing the first gate oxide film 7 in the curvature portion with the LOCOS 8 that is the second gate oxide film, the voltage shared by the LOCOS 8 between the gate electrode 10 in the curvature portion and the n-type well region 4 can be obtained. As a result, the electric field concentration in the surface region of the n-type well region 4 immediately below the gate electrode 7 is alleviated. Therefore, even if a high voltage of 170 V is applied between the source and the drain, the device does not break down and the voltage is 170 V. High on-withstand voltage is ensured and normal operation is achieved. That is, the on-breakdown voltage of the thick film gate HVPMOS of the present invention can be made higher than the on-breakdown voltage of the conventional thick film gate HVPMOS.

尚、本実施例において、第2ゲート酸化膜はLOCOS8と同じに形成することにより、第2ゲート酸化膜とLOCOS8とは1つのLOCOSにより形成されるが、第2ゲート酸化膜はLOCOS8とは別々に形成してもよく、また、第1ゲート酸化膜7より厚ければ第1ゲート酸化膜より電圧分担する電圧を増すことができるため第1ゲート酸化膜7より厚ければよい。   In this embodiment, the second gate oxide film and the LOCOS 8 are formed by one LOCOS by forming the second gate oxide film in the same manner as the LOCOS 8, but the second gate oxide film is different from the LOCOS 8. In addition, if it is thicker than the first gate oxide film 7, the voltage shared by the first gate oxide film can be increased.

また、第1ゲート酸化膜7、第2ゲート酸化膜は材料が同じであれば他の絶縁膜であってもよい。   The first gate oxide film 7 and the second gate oxide film may be other insulating films as long as the materials are the same.

図7は、この発明の第2実施例の高耐圧横型MOSFETの要部構成図であり、同図(a)は平面図、同図(b)は同図(a)のX−X線で切断した断面図、同図(c)は同図(a)のY−Y線で切断した断面図である。同図(b)は図4(b)と同じである。
図4との違いは、曲率部分のゲート電極を削除した点である。即ち、ゲート電極は図4(a)の直線部分のみに形成している。また、同図(c)に示すように曲率部分のゲート酸化膜7上にはゲート電極を形成しない。
FIGS. 7A and 7B are main part configuration diagrams of a high breakdown voltage lateral MOSFET according to a second embodiment of the present invention. FIG. 7A is a plan view, and FIG. 7B is an XX line of FIG. The cut cross-sectional view and FIG. 4C are cross-sectional views taken along line YY of FIG. FIG. 4B is the same as FIG.
The difference from FIG. 4 is that the gate electrode in the curvature portion is deleted. That is, the gate electrode is formed only on the straight line portion of FIG. Further, as shown in FIG. 3C, no gate electrode is formed on the gate oxide film 7 in the curvature portion.

この構造により、Vgsに高電圧が印加されても曲率部分で高電界が発生することはない。よって、本発明の厚膜ゲートHVPMOSのオン耐圧は、従来の厚膜ゲートHVPMOSのオン耐圧より高くすることができる。
尚、図1においても、図7に示すように曲率部分のゲート電極を削除しても構わない。
With this structure, even when a high voltage is applied to Vgs, a high electric field is not generated in the curvature portion. Therefore, the on-breakdown voltage of the thick film gate HVPMOS of the present invention can be made higher than the on-breakdown voltage of the conventional thick film gate HVPMOS.
In FIG. 1 as well, the gate electrode in the curvature portion may be deleted as shown in FIG.

この発明の第1実施例の高耐圧横型MOSFETの要部構成図であり、(a)は平面図、(b)は(a)のX−X線で切断した断面図、(c)は(a)のY−Y線で切断した断面図BRIEF DESCRIPTION OF THE DRAWINGS It is a principal part block diagram of the high voltage | pressure-resistant lateral MOSFET of 1st Example of this invention, (a) is a top view, (b) is sectional drawing cut | disconnected by the XX line of (a), (c) is ( Sectional drawing cut | disconnected by the YY line of a) 本発明品のオン耐圧曲線図ON breakdown voltage curve of the product of the present invention 厚膜ゲートHVPMOSを適用したレベルシフト回路の一例を示す図The figure which shows an example of the level shift circuit to which thick film gate HVPMOS is applied 従来の厚膜ゲートHVPMOSの構成図であり、(a)は要部平面図、(b)は(a)のX−X線で切断した要部断面図、(c)は(a)のY−Y線で切断した要部断面図It is a block diagram of the conventional thick film gate HVPMOS, (a) is a principal part top view, (b) is principal part sectional drawing cut | disconnected by the XX line of (a), (c) is Y of (a). Cross-sectional view of the main part taken along line -Y 従来の厚膜ゲートHVPMOSの曲率部分での等電位線を示した図The figure which showed the equipotential line in the curvature part of the conventional thick film gate HVPMOS 従来の厚膜ゲートHVPMOSのオン耐圧曲線図ON breakdown voltage curve of conventional thick gate HVPMOS この発明の第2実施例の高耐圧横型MOSFETの要部構成図であり、(a)は平面図、(b)は(a)のX−X線で切断した断面図、(c)は(a)のY−Y線で切断した断面図It is a principal part block diagram of the high voltage | pressure-resistant lateral MOSFET of 2nd Example of this invention, (a) is a top view, (b) is sectional drawing cut | disconnected by the XX line of (a), (c) is ( Sectional drawing cut | disconnected by the YY line of a)

符号の説明Explanation of symbols

1 n型半導体基板
2 p型オフセット領域
3 p型ドレイン領域
4 n型ウェル領域
5 p型ソース領域
6 n型コンタクト領域
7 ゲート酸化膜
8 LOCOS
9 ソース電極
10 ゲート電極
11 ドレイン電極
D ドレイン端子
G ゲート端子
S ソース端子
A 出力回路部
B レベルシフト回路部
N1,N2 IGBT
N3,N4 nチャネルMOSFET
P1,P2 pチャネルMOSFET
ZD ツェナーダイオード
VH 出力側電圧電源の高電位側端子
GND グランド
Vin1,Vin2,Vin3 ゲート信号
Vout 出力端子
1 n-type semiconductor substrate 2 p-type offset region 3 p-type drain region 4 n-type well region 5 p-type source region 6 n-type contact region 7 gate oxide film 8 LOCOS
9 Source electrode 10 Gate electrode 11 Drain electrode D Drain terminal G Gate terminal S Source terminal A Output circuit part B Level shift circuit part N1, N2 IGBT
N3, N4 n-channel MOSFET
P1, P2 p-channel MOSFET
ZD Zener diode VH Output side voltage power supply high potential side terminal GND Ground Vin1, Vin2, Vin3 Gate signal Vout output terminal

Claims (6)

ドレイン電極とソース電極とが平行に形成された直線部分とドレイン電極をソース電極が取り囲む曲率部分とを備え、前記ドレイン電極と前記ソース電極との間にゲート電極が配置された平面パターンを有する横型MOSFETにおいて、
前記直線部分の前記ゲート電極下に位置する第1ゲート絶縁膜の厚さより前記曲率部分の前記ゲート電極下の第2ゲート絶縁膜の方が厚いことを特徴とする高耐圧横型MOSFET。
A horizontal type comprising a straight line portion in which a drain electrode and a source electrode are formed in parallel and a curvature portion surrounding the drain electrode by the source electrode, and a planar pattern in which a gate electrode is disposed between the drain electrode and the source electrode In MOSFET,
The high breakdown voltage lateral MOSFET, wherein the second gate insulating film under the gate electrode in the curvature portion is thicker than the thickness of the first gate insulating film located under the gate electrode in the straight portion.
前記直線部分は、
第1導電型の半導体層の表面層に選択的に形成された第1導電型のウェル領域と、前記半導体層の表面層に前記ウェル領域から離して選択的に形成された第2導電型のオフセット領域と、前記ウェル領域の表面層に選択的に形成された第2導電型のソース領域と、前記オフセット領域の表面層に選択的に形成された第2導電型のドレイン領域と、前記ウェル領域の表面層に選択的に形成された第1導電型のコンタクト領域と、前記ソース領域と前記オフセット領域に挟まれた前記半導体層上と前記ウェル領域上に前記第2ゲート絶縁膜を介して形成されたゲート電極と、前記第1ゲート絶縁膜と接し前記オフセット領域上を覆う前記第2ゲート絶縁膜より厚い第1フィールド絶縁膜とを備え、前記ドレイン電極が前記ドレイン領域と接し、前記ソース電極が前記ソース領域と前記コンタクト領域と接し、
前記曲率部分は、
前記ウェル領域と、前記オフセット領域と、前記ドレイン領域と、前記コンタクト領域と、前記ウェル領域の上から前記オフセット領域上に亘って形成される前記第2ゲート絶縁膜を介して形成された前記ゲート電極と、前記第2ゲート絶縁膜と接し前記オフセット領域上を覆う前記第1フィールド絶縁膜と同じ厚さの第2フィールド絶縁膜とを備え、前記ドレイン電極が前記ドレイン領域と接し、前記ソース電極が前記コンタクト領域と接することを特徴とする請求項1に記載の高耐圧横型MOSFET。
The straight portion is
A first conductivity type well region selectively formed on the surface layer of the first conductivity type semiconductor layer; and a second conductivity type well region selectively formed on the surface layer of the semiconductor layer apart from the well region. An offset region; a second conductivity type source region selectively formed on a surface layer of the well region; a second conductivity type drain region selectively formed on a surface layer of the offset region; and the well A contact region of a first conductivity type selectively formed on the surface layer of the region, the semiconductor layer sandwiched between the source region and the offset region, and the well region via the second gate insulating film A gate electrode formed, and a first field insulating film that is in contact with the first gate insulating film and is thicker than the second gate insulating film covering the offset region, the drain electrode being in contact with the drain region, The source electrode is in contact with the source region and the contact region,
The curvature portion is
The gate formed through the well region, the offset region, the drain region, the contact region, and the second gate insulating film formed from above the well region to the offset region. An electrode, and a second field insulating film having the same thickness as the first field insulating film that contacts the second gate insulating film and covers the offset region, wherein the drain electrode is in contact with the drain region, and the source electrode The high withstand voltage lateral MOSFET according to claim 1, wherein is in contact with the contact region.
前記第2フィールド絶縁膜と前記第2ゲート絶縁膜とが同じ厚さであることを特徴とする請求項2に記載の高耐圧横型MOSFET。   The high breakdown voltage lateral MOSFET according to claim 2, wherein the second field insulating film and the second gate insulating film have the same thickness. 前記第1フィールド絶縁膜、前記第2フィールド絶縁膜および前記第2ゲート絶縁膜が1つのLOCOS(選択酸化膜)であることを特徴とする請求項3に記載の高耐圧横型MOSFET。   4. The high breakdown voltage lateral MOSFET according to claim 3, wherein the first field insulating film, the second field insulating film, and the second gate insulating film are one LOCOS (selective oxide film). ドレイン電極とソース電極とが平行に形成された直線部分とドレイン電極をソース電極が取り囲む曲率部分とを備え、前記ドレイン電極と前記ソース電極との間にゲート電極が配置された平面パターンを有する横型MOSFETにおいて、
前記ゲート電極が前記直線部分のみに形成されることを特徴とする高耐圧横型MOSFET。
A horizontal type comprising a straight line portion in which a drain electrode and a source electrode are formed in parallel and a curvature portion surrounding the drain electrode by the source electrode, and a planar pattern in which a gate electrode is disposed between the drain electrode and the source electrode In MOSFET,
The high breakdown voltage lateral MOSFET, wherein the gate electrode is formed only in the straight portion.
前記直線部分は、
第1導電型の半導体層の表面層に選択的に形成された第1導電型のウェル領域と、前記半導体層の表面層に前記ウェル領域から離して選択的に形成された第2導電型のオフセット領域と、前記ウェル領域の表面層に選択的に形成された第2導電型のソース領域と、前記オフセット領域の表面層に選択的に形成された第2導電型のドレイン領域と、前記ウェル領域の表面層に選択的に形成された第1導電型のコンタクト領域と、前記ソース領域と前記オフセット領域に挟まれた前記半導体層上と前記ウェル領域上にゲート絶縁膜を介して形成されたゲート電極と、前記ゲート絶縁膜と接し前記オフセット領域上を覆うフィールド絶縁膜とを備え、前記ドレイン電極が前記ドレイン領域と接し、前記ソース電極が前記ソース領域と前記コンタクト領域と接し、
前記曲率部分は、
前記ウェル領域と、前記オフセット領域と、前記ドレイン領域と、前記コンタクト領域と、前記ウェル領域の上から前記オフセット領域上に亘って形成されるゲート絶縁膜と、前記ゲート絶縁膜と接し前記オフセット領域上を覆うフィールド絶縁膜とを備え、前記ドレイン電極が前記ドレイン領域と接し、前記ソース電極が前記コンタクト領域と接することを特徴とする請求項5に記載の高耐圧横型MOSFET。
The straight portion is
A first conductivity type well region selectively formed on the surface layer of the first conductivity type semiconductor layer; and a second conductivity type well region selectively formed on the surface layer of the semiconductor layer apart from the well region. An offset region; a second conductivity type source region selectively formed on a surface layer of the well region; a second conductivity type drain region selectively formed on a surface layer of the offset region; and the well A contact region of a first conductivity type selectively formed on a surface layer of the region, a gate insulating film formed on the semiconductor layer and the well region sandwiched between the source region and the offset region A gate electrode; and a field insulating film in contact with the gate insulating film and covering the offset region, wherein the drain electrode is in contact with the drain region, and the source electrode is in contact with the source region. Frequency and contact,
The curvature portion is
The well region, the offset region, the drain region, the contact region, a gate insulating film formed from above the well region to the offset region, and in contact with the gate insulating film, the offset region 6. The high breakdown voltage lateral MOSFET according to claim 5, further comprising a field insulating film covering the upper surface, wherein the drain electrode is in contact with the drain region, and the source electrode is in contact with the contact region.
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