【発明の詳細な説明】
本発明は半導体のピエゾ効果薔こより、被検出圧力を電
気量に変換して測定する半導体圧力センサ特にダイヤフ
ラム部の温度変化にもとづく計測誤差の排除に関するも
のである。半導体圧力センサは第１図（ａ）（ｂ）に示
す平面図およびその人−に部矢視断面図のように、半導
体（１）例えばＮａ３ ｉ単結晶ウェハ舊こ、エツチン
グにより凹部（１ａ）例えば角形溝を設けて形成された
ダイヤフラム部（起歪部）（２）と、その−両番ζ間隔
をおいて十字状かつ長手方向が結晶方向と同一番ζ位置
するよう番ζＰ型拡激して設けた同一抵抗値の４箇のピ
エゾ抵抗素子（３ｍ）（３ｍ）（３ｍ）（３，）とから
形成される。そして各抵抗素子（３）をその電極を用い
て（図示せず）第２図に示すように、ブリッジ回路（４
）を形成するように接続して、ダイヤフラム部（２）に
被検測圧力Ｐを加え。DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a semiconductor pressure sensor that uses the piezoelectric effect of a semiconductor to measure a detected pressure by converting it into an electrical quantity, particularly to eliminate measurement errors due to temperature changes in a diaphragm portion. As shown in the plan view and cross-sectional view shown in FIGS. 1(a) and 1(b), the semiconductor pressure sensor is made of a semiconductor (1), for example, a Na3i single crystal wafer, and is etched into a recess (1a). For example, a diaphragm part (strain part) (2) formed with a square groove, and a cross-shaped diaphragm part (strain part) (2) formed with a square groove, and a ζP type expansion so that the longitudinal direction is at the same first ζ position as the crystal direction. It is formed from four piezoresistive elements (3m) (3m) (3m) (3,) having the same resistance value and provided as follows. Then, each resistive element (3) is connected to a bridge circuit (4) using its electrode (not shown) as shown in FIG.
) and apply the measured pressure P to the diaphragm part (2).
これにもとづく抵抗素子（３１）（３，）と（３，）（
３ｓ）の抵抗の変化の相異により、ブリッジ回路に不平
衡状態を生じ−させて、出力端子（５ａ）（ｓ−ｂ）か
ら圧力Ｐに比例した電圧ΔＶを得るようにしたものであ
る。なお、（６ａ ）（６ｂ）は電源端子である。とこ
ろでこのような圧力センサーでは、第３図番ζ示すよう
に各抵抗素子（３８〜３．）の温度依存性が大きく因み
に特性（イ）に示す如く０℃の時の感度を１．０とする
と１００℃では０．８に低下する。従って出力端子（５
ａ、５ｂ）からの電圧（ΔＶ）は温度により変化し、測
定誤差の原因となる。そこで一般１ｉ前記感度変化を除
去（特性口）すべくサーミス〃或はポジスタ等の感温素
子を設けて温度補グを行い前記電源端子（６ａ）（６ｂ
）間の印加電圧を上昇せしめて前記各抵抗素子（３１〜
３、）の抵抗変化（ΔＲ）を補償している。しかし乍ら
上記感温素子はセンサ（ブリッジ抵抗と個別に形成され
、しかも離れた所に配置されるため温度補償精度の向上
をはかることが困難であった。本発明は係る点を鑑み、
センサ素子と感温素子を共通半導体基板に一体に形成す
ると共に前記感温素子として複数個のダイオード群を用
いて上記の問題を解消した安価なセンサを提供するもの
である。第４図は本発明の一実施例構造を示す断面図で
従来例と同一符号は同等部分を示す。図中７はＰ型領域
（部）、８はＮ型領域（部）でこれによりＰＮＮ接合を
有する１つのダイオードを構成している。（図ではダイ
オード３個の例を示ス、）この製法はＮ型シリコン基板
（１）にＰ型拡散抵抗素子（３８、ａｔ）をダイヤフラ
ムの起歪部（２）上に形成してブリッジ化すると共に上
記Ｐ型抵抗形成時ζこ同時にＰ型領域（７１％形成する
。（不純物濃度は略１０．１１／−）次いで該Ｐ型領域
（７）に更にＮ型不純物（濃度略１０１’／ｊ）を拡散
し、Ｎ型領域（８）を形成する。次に該基板全面に、酸
化膜を形成し写真処理で所要部の窓開及びアルミ蒸着し
、該ダイオードをＰＮ−ＰＮとなる如く接続しシリーズ
化する。因み番とＰＮ接合（ダイオード）の順方向特性
は一２ｍＶ／’Ｃとよく知られた直線的温度特性を持っ
ている。本発明は係るダイオード（ＤＪの測温特性を利
用しブリッジの印加電圧を直線的に補償するようにした
ものである。オペアンプの入力ζこ温度補償ダイオード
を入れることはダイオードの順方向電圧は０．６ｖ位な
のでブリッジの印加電圧を５ｖ位とすると（ｓＶ／Ｑ、
６ａ＝ｑｓＪ９８佃位をシリーズにして電圧を稼ぐ必要
がある。Resistance elements based on this (31) (3,) and (3,) (
3s) causes an unbalanced state in the bridge circuit to obtain a voltage ΔV proportional to the pressure P from the output terminals (5a) (sb). Note that (6a) and (6b) are power supply terminals. By the way, in such a pressure sensor, as shown in Figure 3, the temperature dependence of each resistance element (38 to 3.) is large.Incidentally, as shown in characteristic (a), the sensitivity at 0°C is 1.0. Then, at 100°C, it decreases to 0.8. Therefore, the output terminal (5
The voltage (ΔV) from a, 5b) varies with temperature, causing measurement errors. Therefore, in general 1i, in order to eliminate the sensitivity change (characteristic port), a temperature sensing element such as a thermistor or posistor is provided to compensate for the temperature, and the power terminals (6a) (6b)
) by increasing the applied voltage between each of the resistive elements (31 to 31).
3.) The resistance change (ΔR) is compensated for. However, since the above-mentioned temperature sensing element is formed separately from the sensor (bridge resistor) and placed in a remote location, it has been difficult to improve the temperature compensation accuracy.
The present invention provides an inexpensive sensor in which a sensor element and a temperature sensing element are integrally formed on a common semiconductor substrate, and a plurality of diode groups are used as the temperature sensing element to solve the above problems. FIG. 4 is a sectional view showing the structure of an embodiment of the present invention, and the same reference numerals as in the conventional example indicate the same parts. In the figure, 7 is a P-type region (part) and 8 is an N-type region (part), which constitute one diode having a PNN junction. (The figure shows an example of three diodes.) This manufacturing method forms a bridge by forming a P-type diffused resistance element (38, at) on the strain-generating part (2) of the diaphragm on an N-type silicon substrate (1). At the same time, when forming the P-type resistor ζ, a P-type region (71%) is formed at the same time (the impurity concentration is approximately 10.11/-). Then, an N-type impurity (concentration approximately 101'/-) is further added to the P-type region (7). j) to form an N-type region (8).Next, an oxide film is formed on the entire surface of the substrate, windows are opened in the required parts by photo processing, and aluminum is deposited, so that the diode becomes PN-PN. The forward characteristics of the diode and the PN junction (diode) have a well-known linear temperature characteristic of -2 mV/'C. The voltage applied to the bridge is linearly compensated by using the input voltage of the operational amplifier.Inserting a temperature compensation diode means that the forward voltage of the diode is about 0.6V, so the voltage applied to the bridge is reduced to about 5V. Then (sV/Q,
It is necessary to connect 6a=qsJ98 in series to generate voltage.
第５図は本発明の圧力センサを用いた電気回路図でＥ、
は定電圧直流電源、ｒ＋ｑｒｔは分圧抵抗、ＯＰＭはオ
ペアンプ（差動増巾器）４及メＤは上述の如く一体に形
成されたブリ、ジ回路及び感温用ダイオードで前記ダイ
オードｐ）は抵抗ｒ、を介して電源′Ｂ、間に接続され
、その接続点（ａ）をオペアンプＯＰＭの検出側（ハ）
に入力される。一方ブリッジ肌路４は前記オペアンプＯ
ＰＭの出力−ｂ）とアース間（ｍＷ（ハ）端月こ接続さ
れる。この回路によればＰＮ接合のシリーズ部勧）で感
温すると一２ｍＶＸ８コ／’Ｃの率で電圧が上がるがこ
の変化がオペアンプ（ＯＰＭ）に入力し反転入力のため
出力はＲ＊ ／Ｒ＋で増１】シ、ブリッジの印加電圧を
変化させる。ＰＮダイオードＤの電圧は直線的に減少し
オペアンプＯＰＭは直線的に増加するのでブリッジの感
度が温度で低下する分を補償できる。因みに従来例にお
いて３％の誤差を０，５％以下にできることが確認され
た。なお、抵抗Ｒ１、Ｒ＊はトリミングとし一度調整す
ることによって精度が補償される。又ＰＮダイオード（
０，１ｍ Ａ ７０゜３ ｍ Ａ ）は必要に応じて複
数個シリーズ化すればよくオペアンプＯＰＭの入力に対
し高精度の電圧設定が可能である。以上の実施例では半
導体基板にダイオードを一体に形成した例について説明
したがこの他該基板にセンサ部及びダイオードと区画さ
れた領域を設は該領域内にトランジスタ等よりなるオペ
アンプ（ＯＰＭ）を同時に形成して集積（ＩＣ）化する
ようにしてもよい。以上の説明から明らかなように本発
明によれば共通基板にセンナ部及び感温部を一体に形成
したのでセンサの小型（集積）軽量化が可能であると共
化温度変化による測定誤差を容易に除去し得る高精度の
センサが提供できるので実用上の効果は大きい。FIG. 5 is an electric circuit diagram using the pressure sensor of the present invention.
is a constant voltage DC power supply, r+qrt is a voltage dividing resistor, OPM is an operational amplifier (differential amplifier), 4 and D are integrated circuits, diode circuits, and temperature sensing diodes as described above, and the diode p) is The connection point (a) is connected to the detection side (c) of the operational amplifier OPM.
is input. On the other hand, the bridge surface path 4 is connected to the operational amplifier O.
When temperature is sensed between the PM output - b) and the ground (mW (c) terminal is connected. According to this circuit, the series part of the PN junction is recommended), the voltage increases at a rate of -2 mV x 8 cm/'C. This change is input to the operational amplifier (OPM), and since it is an inverted input, the output is increased by R*/R+.1] The voltage applied to the bridge is changed. Since the voltage of the PN diode D decreases linearly and the voltage of the operational amplifier OPM increases linearly, it is possible to compensate for the decrease in sensitivity of the bridge due to temperature. Incidentally, it has been confirmed that the error of 3% in the conventional example can be reduced to 0.5% or less. Note that the accuracy is compensated by trimming the resistors R1 and R* and adjusting them once. Also, PN diode (
0.1 mA 70°3 mA) can be made into a series of multiple units as necessary, and highly accurate voltage setting for the input of the operational amplifier OPM is possible. In the above embodiment, an example was explained in which a diode was integrally formed on a semiconductor substrate, but it is also possible to provide an area separated from a sensor section and a diode on the substrate, and simultaneously install an operational amplifier (OPM) consisting of a transistor or the like within the area. It may be formed and integrated (IC). As is clear from the above description, according to the present invention, since the sensor part and the temperature sensing part are integrally formed on a common substrate, the sensor can be made smaller (integrated) and lighter, and measurement errors due to temperature changes can be easily reduced. This has a great practical effect because it can provide a highly accurate sensor that can be removed easily.
【図面の簡単な説明】[Brief explanation of the drawing]
第１図、第２図、第３図は従来センサの説明図であって
、このうち沈１図（ａ）（ｂｌは圧力検出部の構成を示
す平面図およびそのＡ−Ａ部における矢視断面図、第２
図は電気回路図、第３図は感度と温度との関係を示す特
性図、第４図は本発明の一実施例構造を示す断面図、第
５図は電気回路図である。図において１は半導体基板、
１ａは溝、２はダイヤフラム、３はピエゾ抵抗素子群、
４はブリッジ回路、５ａ、５ｂは出力端子、６ａ、６ｂ
は電源端子、７はＰ型領域、８はＮ型領域、ＪはＰＮ接
合、Ｄはダイオード群、ＯＰＭはオペアンプ（差動増巾
器）、Ｅ。
は定電圧直流電源である。
特許出願人 新電元工業株式会社
劇（１ｃ）
第２図 第、３゜Figures 1, 2, and 3 are explanatory diagrams of conventional sensors, in which Figures 1(a) (bl) are plan views showing the configuration of the pressure detection section, and arrows in the A-A section thereof. Cross section, 2nd
3 is a characteristic diagram showing the relationship between sensitivity and temperature, FIG. 4 is a sectional view showing the structure of an embodiment of the present invention, and FIG. 5 is an electric circuit diagram. In the figure, 1 is a semiconductor substrate,
1a is a groove, 2 is a diaphragm, 3 is a piezoresistive element group,
4 is a bridge circuit, 5a, 5b are output terminals, 6a, 6b
is a power supply terminal, 7 is a P-type region, 8 is an N-type region, J is a PN junction, D is a diode group, OPM is an operational amplifier (differential amplifier), and E. is a constant voltage DC power supply. Patent applicant Shindengen Kogyo Co., Ltd. Geki (1c) Figure 2, 3゜