JP2006237104A - Semiconductor element for surge protection, and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a semiconductor element for a surge protection having a plurality of LEDs in the serial connection. <P>SOLUTION: In an n-type semiconductor substrate 2, p-type regions 3a and 3b and n-type regions 4a and 4b are formed. An LED is connected electrically between an anode electrode 6a and a cathode electrode 7a, and between an anode electrode 6b and a cathode electrode 7b. Zener diodes D34a and D34b configured by the n-type regions 4a and 4b and the p-type regions 3a and 3b have a breakdown voltage larger than the forward drop voltage in usual when each LED is used in usual, and it designs so that it may become under the withstand voltage of each LED. Isolation diodes D32a and D32b configured by the p-type regions 3a and 3b and the n-type semiconductor substrate 2 are designed so that the breakdown voltage may become higher than the sum of the forward drop voltages of all the LEDs. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a semiconductor device for surge protection and a method for manufacturing the same.

  In recent years, light emitting diodes (LEDs) have been used in many fields. Since an LED is made of a compound semiconductor such as GaAs (gallium arsenide) or GaN (gallium nitride), it is very weak against surges such as electrostatic discharge (ESD). Therefore, since an LED needs a surge protection circuit, an LED package in which a surge protection semiconductor element (zener diode) is enclosed in advance has been proposed (see, for example, Patent Document 1).

FIG. 10A shows an example of the LED package 111 in which the surge protection semiconductor element 100 is enclosed. FIG. 10B is a circuit diagram of FIG. The LED package 111 includes an LED 112, a surge protection semiconductor element 100, metal frames 101a and 101b, and a sealing portion 113 made of a light transmissive resin. The surge protection semiconductor element 100 is a flip-chip type Zener diode including an N-type semiconductor substrate 102, a P-type region 103, an insulating film 105, a cathode electrode 106, an anode electrode 107, and a back electrode 108. A surge current branch circuit is configured by the semiconductor element 100 for surge protection connected in parallel to the LED 112.
JP 2002-185049 A

  Recently, there is an increasing demand for improving the brightness of LEDs, and in order to satisfy this demand, an LED package in which a plurality of LEDs are enclosed has been proposed. However, an LED package in which a semiconductor element for surge protection is enclosed with a plurality of LEDs has not been proposed yet.

  For example, when a plurality of surge protection semiconductor elements 100 and LEDs 112 shown in FIG. 10A are enclosed in an LED package, it is difficult to reduce the size of the LED package. Therefore, the present inventor has studied to develop a flip-chip type surge protection semiconductor element on which a plurality of LEDs can be mounted in order to reduce the size of the LED package. At that time, the following problems have arisen.

  It is desirable that the luminance change of the LED package (light source) is isotropic, and for this purpose, the luminance of each LED in the LED package needs to be substantially the same. The brightness of the LED is determined in proportion to the current value supplied to the LED.

  When the LEDs are connected in parallel, the current value is determined according to the resistance value of each LED, so that the brightness of the LED varies due to the variation in the resistance value of each LED due to manufacturing errors. Therefore, when LEDs are connected in parallel, it is necessary to provide a peripheral circuit for correcting variations in resistance values of the LEDs to make the brightness of the LEDs uniform. In that case, since the peripheral circuit becomes complicated, it is difficult to reduce the size of the LED package.

  On the other hand, when the LEDs are connected in series, the current value supplied to each LED is constant, so there is no need to adjust the resistance value for brightness adjustment. Therefore, if the LEDs are connected in series, the brightness of each LED in the package can be made uniform and the peripheral circuit can be simplified.

  However, when a single surge protection semiconductor element is configured by simply arranging a plurality of conventional surge protection semiconductor elements shown in FIG. 10A, FIG. 11 and FIG. As shown, since the back electrode 108 is shared, the LEDs 112a and 112b cannot be connected in series.

  Therefore, an object of the present invention is to provide a semiconductor device for surge protection capable of mounting a plurality of LEDs connected in series.

  A semiconductor device for surge protection according to the present invention is a semiconductor device for surge protection provided with a Zener diode that is used by connecting elements to be protected from surge in parallel, and includes a semiconductor substrate of a first conductivity type, and a Zener diode. A plurality of surge protection circuit portions included in the semiconductor substrate, and a back electrode formed on the back surface of the semiconductor substrate, each surge protection circuit portion including a second conductivity type region formed inside from the surface of the semiconductor substrate; A first conductivity type region formed inside from the surface of the two conductivity type region, an insulating film exposing a part of the first conductivity type region and a part of the second conductivity type region, and a first exposed from the insulating film. It has the 1st surface electrode formed in the conductivity type area | region, and the 2nd surface electrode formed in the 2nd conductivity type area | region exposed from the insulating film.

  The magnitude of the breakdown voltage of the Zener diode composed of the first conductivity type region and the second conductivity type region is larger than the voltage drop of the element to be protected during normal use and less than the withstand voltage of the element to be protected. Just do it.

  More specifically, it is sufficient that the breakdown voltage of the Zener diode is 3 to 50V.

  In addition, the breakdown voltage of the isolation diode composed of the second conductivity type region and the semiconductor substrate may be higher than the sum of the drop voltages of the elements to be protected during normal use.

  More specifically, the breakdown voltage of the separation diode may be 10 V or more.

  In addition, the surge protection semiconductor device according to the present invention provides all surge protection by connecting the first surface electrode of the surge protection circuit section and the second surface electrode of another surge protection circuit section. You may further provide the wiring which connects the circuit part for a series.

  A method for manufacturing a semiconductor device for surge protection according to the present invention is a method for manufacturing a semiconductor device for surge protection provided with a Zener diode for connecting elements to be protected from surge in parallel, and the surface of a semiconductor substrate of a first conductivity type A step of forming a plurality of second conductivity type regions from the inside, a step of forming the first conductivity type region from the surface of each second conductivity type region, a part of the first conductivity type region and the second conductivity Forming an insulating film exposing a part of the mold region, forming first and second surface electrodes in the first conductive type region and the second conductive type region exposed from the insulating film, Forming a back electrode on the back surface of the semiconductor substrate.

  According to the semiconductor device for surge protection according to the present invention, the mounting surface area can be reduced as compared with the case where a chip-like semiconductor device for surge protection is individually connected to one LED. The circuit can also be simplified. Therefore, if the semiconductor element for surge protection according to the present invention is used, a smaller LED package can be realized.

  The semiconductor element for surge protection according to the present embodiment has a configuration in which LEDs can be connected in series and one surge protection circuit unit can be connected in parallel to each LED. When the LEDs are connected in series, the current values supplied to the LEDs are equal, so that the brightness of the LEDs is uniform. Therefore, if this semiconductor element is used, an LED package in which the luminance change is isotropic can be realized.

  Moreover, since the semiconductor element for surge protection according to the present invention includes the isolation diode, each surge protection circuit unit can be individually handled as an electrically isolated element. Therefore, if the semiconductor element for surge protection according to the present invention is used, the degree of freedom in designing a circuit on which it is mounted is increased.

  If wiring for connecting the surface electrodes is provided, it is not necessary to connect the electrodes. There is also an advantage that the polarities of the first surface electrode and the second surface electrode can be distinguished visually.

(First embodiment)
1A and 1B are a plan view and a cross-sectional view taken along line AA ′ of a surge protection semiconductor element 10 (hereinafter simply referred to as a semiconductor element 10) according to a first embodiment of the present invention. Show. The semiconductor element 10 includes an N-type semiconductor substrate 2, P-type regions 3a and 3b, N-type regions 4a and 4b, an insulating film 5, anode electrodes 6a and 6b, cathode electrodes 7a and 7b, and a back electrode 8. .

  The P-type region 3a, the N-type region 4a, the anode electrode 6a, and the cathode electrode 7a constitute a first surge protection circuit portion 9a. Further, the P-type region 3b, the N-type region 4b, the anode electrode 6b, and the cathode electrode 7b constitute a second surge protection circuit portion 9b.

  The P-type regions 3a and 3b are regions formed in the interior from the surface of the N-type semiconductor substrate 2 and having a high P-type impurity concentration. The depths of the P-type regions 3a and 3b are d1, and the planar shape is a circular shape having a radius R1. The N-type regions 4a and 4b are regions having a high N-type impurity concentration formed from the surface of the P-type regions 3a and 3b to the inside. The depths of the N-type regions 4a and 4b are d2 (<d1), and the planar shape thereof is a circular shape having a radius R2 (<R1). In order to easily determine the polarity, the anode electrodes 6a and 6b and the cathode electrodes 7a and 7b have different diameters.

  In the first and second surge protection circuit portions 9a and 9b, PN-junction P-type regions 3a and 3b and N-type regions 4a and 4b constitute zener diodes D34a and D34b on the circuit described later. (See FIG. 3). Further, the PN junction P-type regions 3a and 3b and the N-type semiconductor substrate 2 constitute separation diodes D32a and D32b on a circuit to be described later (see FIG. 3).

  FIG. 2 shows an LED package 11 which is an example of a usage mode of the semiconductor element 10. FIG. 3 shows a circuit diagram of FIG. The LED package 11 includes a semiconductor element 10, LEDs 12a and 12b, metal frames 1a to 1c, and a sealing portion 13 made of a light transmissive resin.

  The semiconductor element 10 is disposed on the metal frame 1b. The metal frame 1b is grounded or used in a flow state. The anode electrode 6a is electrically connected to the metal frame 1a, and the cathode electrode 7b is electrically connected to the metal frame 1c by wires. LED12a is arrange | positioned on the anode electrode 6a, The P side electrode is electrically connected with the cathode electrode 7a by the wire. The LED 12b is disposed on the anode electrode 6b, and its P-side electrode is electrically connected to the cathode electrode 7b by a wire. The anode electrode 6b and the cathode electrode 7a are electrically connected by a wire. As described above, the series connection of the LEDs 12a and 12b between the metal frames 1a and 1c is realized. During normal use, a normal voltage is applied between the metal frames 1a and 1c so that the metal frame 1c side is a plus side. The forward voltage drop of the LEDs 12a and 12b during normal use is defined as Vf.

The Zener diodes D34a and D34b are designed so that the Zener breakdown voltage Vz (D34) satisfies the condition expressed by the following equation (1).
Vf <Vz (D34) <Vb (1)
Here, Vb is a withstand voltage of the LEDs 12a and 12b.

  Since the Zener diodes D34a and D34b satisfy the condition shown in the expression (1), when a surge current enters from the metal frames 1a to 1c, an overvoltage higher than the withstand voltage is applied to the LEDs 12a and 12b. In addition, when the normal voltage 2Vf is applied between the metal frames 1a and 1c (between the anode electrode 6a and the cathode electrode 7b), the LEDs 12a and 12b emit light.

  The separation diodes D32a and D32b are connected to each other between the P-type region 3a and the N-type semiconductor substrate 2 by a potential difference between the anode electrode 6a and the cathode electrode 7b when the normal voltage 2Vf is applied between the metal frames 1a and 1c. The condition is that no zener breakdown occurs at the junction. If this condition is satisfied, the surge protection circuit portion 9a and the surge protection circuit portion 9b can be handled as electrically separated elements. If it can be handled as a separate element, there is an advantage that the degree of freedom in circuit design is increased.

In order to satisfy this condition sufficiently, the P-type region 3a and the N-type are set so that the Zener breakdown voltage Vz (D32) between the P-type region 3a and the N-type semiconductor substrate 2 satisfies the following equation (2). The semiconductor substrate 2 may be designed.
Vz (D32)> 2Vf (2)
That is, the P-type regions 3a and 3b may be designed such that the breakdown voltage Vz (D32) is higher than the sum (= 2Vf) of the drop voltage Vf of the LED 12a and the drop voltage Vf of the LED 12b. The value of breakdown voltage Vz (D32) can be adjusted by adjusting the impurity concentrations of P-type regions 3a and 3b and N-type semiconductor substrate 2.

  The breakdown voltage of the Zener diodes D34a and D34b and the breakdown voltage of the separation diodes D32a and D32b are determined by the characteristics and the number of the LEDs 12a and 12b. It is sufficient that the breakdown voltage of D34b is about 3 to 50V and the breakdown voltages of the separation diodes D32a and D32b are 10V or more.

As representative structural parameters that satisfy such conditions, the N-type semiconductor substrate 2 has an N-type impurity concentration of 10 ¹³ to 10 ¹⁸ cm ⁻³ , a thickness of 100 to 400 μm, and P in the P-type regions 3a and 3b. The type impurity concentration is 10 ¹⁸ to 10 ²⁰ cm ⁻³ , the depth d 1 is 10 to 30 μm, the N type impurity concentration of the N type regions 4 a and 4 b is 10 ¹⁹ to 10 ²¹ cm ⁻³ , and the depth d 2 is 5 to 5. 10 μm.

Although FIG. 1 shows the case where two surge protection circuit portions 9a and 9b are provided on the N-type semiconductor substrate 2, if the above conditions are satisfied, the surge protection circuit portions 9a and 9b Any number may be used. For example, when the N-type impurity concentration of the N-type semiconductor substrate 2 is 10 ¹⁴ cm ⁻³ and the thickness thereof is 150 μm, the P-type impurity concentration of the P-type region 3a is 10 ¹⁹ cm ⁻³ and the depth d1 is 20 μm. When the N-type impurity concentration of the N-type region 4a is 10 ²¹ cm ⁻³ and the depth d2 is 5 μm, the breakdown voltage of the Zener diode D34a is Vz (D34) = 7V, and the breakdown voltage of the isolation diode D32a However, Vz (D32) = 60V. Therefore, when the forward voltage drop of the LED 12a is 2V, even when up to 30 surge protection circuit portions 9α are connected in series, the surge protection circuit portions 9α can be electrically separated.

  In the LED package 11 shown in FIG. 2, the current path when the surge current enters will be described separately when the metal frame 1b is in the flow state and when it is grounded. First, when a surge current (+ Is) enters from the metal frame 1c when the metal frame 1b is in the flow state, first, the current is shunted by the cathode electrode 7b, one of which is the LED 12b in the forward direction, and the other is the zener diode. It flows through D34b in the reverse direction. The current obtained by adding these currents is again shunted by the cathode electrode 7a, one of which flows through the LED 12a in the forward direction and the other of which flows through the Zener diode D34a in the reverse direction, and flows from the anode electrode 6a to the metal frame 1a.

  When a voltage higher than the withstand voltage is applied to the LEDs 12a and 12b, Zener breakdown occurs in the Zener diodes D34a and D34b, so that no overvoltage is applied to the LEDs 12a and 12b.

  When surge current (+ Is) enters from the metal frame 1a, the anode electrode 6a, the P-type region 3a, the N-type region 4a, the cathode electrode 7a, the anode electrode 6b, the P-type region 3b, and the N-type region 4b. A current flows through the metal frame 1c through the cathode electrode 7b. In this case, the surge current + Is flows through the Zener diodes D34a and D34b in the forward direction.

  When surge current (+ Is) enters from the metal frame 1b, the current flows from the anode electrode 6a to the metal frame 1a through the back electrode 8, the N-type semiconductor substrate 2, and the P-type region 3a. Further, a part of the current flows from the cathode electrode 7b to the metal frame 1c through the N-type region 4a, the cathode electrode 7a, the anode electrode 6b, the P-type region 3b, and the N-type region 4b from the P-type region 3a.

  On the other hand, when a surge current (+ Is) enters the metal frame 1c while the metal frame 1b is grounded, the cathode electrode 7b, the N-type region 4b, the P-type region 3b, the N-type semiconductor substrate 2, and the back surface A surge current flows through the electrode 8 to the metal frame 1b. When a surge current (+ Is) enters the metal frame 1a, the surge current escapes to the metal frame 1b through the anode electrode 6a, the P-type region 3a, the N-type semiconductor substrate 2, and the back electrode 8. Therefore, also in this case, a voltage higher than the withstand voltage is not applied to the LEDs 12a and 12b.

  As described above, the semiconductor element 10 according to the present invention can release the surge current to the other metal frames 1a to 1c when the surge current enters from any of the metal frames 1a to 1c, and the LEDs 12a and 12b. No voltage higher than the withstand voltage is applied.

  Next, an example of a method for manufacturing the semiconductor element 10 will be described with reference to FIGS. First, as shown in FIGS. 4A and 4B, P-type regions 3a and 3b are formed by photolithography, impurity doping, and impurity diffusion. More specifically, first, a photomask 14 is formed on the surface of an N-type semiconductor substrate 2 in which an N-type impurity such as phosphorus is doped on a silicon wafer. Then, P-type impurities such as boron are doped from the surface of the N-type semiconductor substrate 2 exposed from the opening and thermally diffused at about 1200 ° C. to form P-type regions 3a and 3b.

  Next, as shown in FIGS. 4C and 4D, N-type regions 4a and 4b are formed by photolithography, impurity doping, and impurity diffusion. More specifically, a photomask 15 is formed on the N-type semiconductor substrate 2, and N-type impurities such as phosphorus are doped from the surfaces of the P-type regions 3a and 3b exposed from the openings, and thermal diffusion is performed at about 1150 ° C. Thus, N-type regions 4a and 4b are formed.

  Next, an insulating film 5 is formed on the N-type semiconductor substrate 2 using thermal oxidation at about 1100 ° C. and chemical vapor deposition (CVD) (FIG. 5E). Then, the insulating film 5 is selectively etched to form contact windows 16a and 16b exposing the partial surfaces of the P-type regions 3a and 3b and the partial surfaces of the N-type regions 4a and 4b (FIG. 5 ( f)). The insulating film 5 may be formed so as to expose the peripheral portion of the surface of the N-type semiconductor substrate 2 or may cover the peripheral portion. As shown in FIG. 5 (f), if the insulating film 5 is formed excluding the peripheral portion of the surface of the N-type semiconductor substrate 2, the stress applied to the insulating film 5 is reduced when the wafer is cut into chips. Can be reduced.

  Next, a metal film is formed on the insulating film 5 by sputtering a material having high conductivity such as aluminum. Then, the metal film is selectively removed by dry etching using a mask to form anode electrodes 6a and 6b and cathode electrodes 7a and 7b (FIG. 5G).

  Finally, titanium, gold, silver, nickel, or a metal containing these is vapor-deposited on the back surface of the N-type semiconductor substrate 2 to form a multilayer or single-layer back electrode 8 (FIG. 5 (h)).

  The semiconductor element 10 according to the present embodiment is a flip chip type surge protection semiconductor element in which a plurality of LEDs can be arranged. According to this semiconductor element 10, the mounting surface area can be reduced and the peripheral circuit can be simplified as compared with the case where a chip-like surge protection semiconductor element is individually connected to one LED. . Therefore, if the semiconductor element for surge protection according to the present invention is used, a smaller LED package can be realized.

  The semiconductor element 10 according to the present embodiment has a configuration in which the LEDs 12a and 12b are connected in series, and each one of the surge protection circuit portions 9a and 9b can be connected in parallel to the LEDs 12a and 12b. When the LEDs 12a and 12b are connected in series, the current values supplied to the LEDs 12a and 12b are equal, so that the brightness of each LED is uniform. Therefore, if this semiconductor element 10 is used, an LED package in which the luminance change is isotropic can be realized.

  In addition, since the semiconductor element 10 according to the present embodiment includes the separation diodes D32a and D32b, a set of the surge protection circuit unit 9a and the LED 12a (surge protection circuit unit / protection target pair) The combination of the surge protection circuit portion 9b and the LED 12b can be individually handled as an electrically separated element. Therefore, if the semiconductor element 10 according to the present invention is used, the degree of freedom in designing a circuit on which the semiconductor element 10 is mounted increases.

  The element to be protected connected between the cathode electrodes 7a and 7b and the anode electrodes 6a and 6b may be an element other than the LED. In the above embodiment, the case where the P-type regions 3a and 3b and the N-type regions 4a and 4b are provided in the N-type semiconductor substrate 2 has been described. However, the present invention also applies to the case where the conductivity type of each part is reversed. It is valid. In that case, a P-type semiconductor substrate is used in place of the N-type semiconductor substrate 2, and, for example, phosphorus is doped and thermally diffused at about 1200 ° C. What is necessary is just to form. Then, boron may be doped into the formed N-type region and thermally diffused at about 1150 ° C. to form a P-type region instead of the N-type regions 4a and 4b.

(Second Embodiment)
6A and 6B are a cross-sectional view of a surge protection semiconductor element 20 (hereinafter referred to as a semiconductor element 20) and a plan view of the N-type semiconductor substrate 2 according to the second embodiment of the present invention. ing. The semiconductor element 20 includes an N-type semiconductor substrate 2, P-type regions 3a to 3c, N-type regions 4a to 4c, an insulating film 5, cathode electrodes 7a to 7c, anode electrodes 6a to 6c, and a back electrode 8. . The N-type semiconductor substrate 2 is provided with three surge protection circuit portions 9a to 9c. In this embodiment, the same reference numerals are given to the components described in the first embodiment, and the description thereof will be omitted.

  In the semiconductor element 20 according to this embodiment, the cathode electrode 7a and the anode electrode 6b, and the cathode electrode 7b and the anode electrode 6c are electrically connected by wirings 22a and 22b. The wires 22a and 22b may be formed simultaneously in the step of forming the cathode electrodes 7a to 7c and the anode electrodes 6a to 6c.

  FIG. 7 shows an LED package 21 which is an example of a usage mode of the semiconductor element 20. FIG. 8 shows a circuit diagram of FIG. The semiconductor element 20 is disposed on the metal frame 1b. The anode electrode 6a is electrically connected to the metal frame 1a, and the cathode electrode 7c is electrically connected to the metal frame 1c by wires. The LEDs 12a to 12c are electrically connected between the anode electrode 6a and the cathode electrode 7a, between the anode electrode 6b and the cathode electrode 7b, and between the anode electrode 6c and the cathode electrode 7c, respectively. Thereby, series connection of LED12a-12c is implement | achieved. Since the semiconductor element 20 is provided with the wirings 22a and 22b in advance, there is no need to connect the electrodes with wires.

  Although the semiconductor element 20 includes three surge protection circuit portions 9a to 9c, the number of surge protection circuit portions 9α (α is a, b...) Provided on the N-type semiconductor substrate 2 is two. Any number is possible as long as it is above.

  For example, FIG. 9 shows an example of a plan view of a surge protection semiconductor element including nine surge protection circuit portions 9a to 9i. LEDs can be arranged in a matrix (3 × 3) and connected in series to this semiconductor element for surge protection. In FIG. 9, the cathode electrode 7α of the surge protection circuit section 9α and the anode electrode 6β of the surge protection circuit section 9β (β is a, b... Nine surge protection circuit portions 9α are connected in series.

  As shown in FIG. 9 and the like, the anode electrodes 6a to 6i and the cathode electrodes 7a to 7i can be easily visually distinguished if the size of the electrodes is changed depending on the polarity, but in addition, the wirings 22a to 22i If it is formed, the position where the LED (not shown) is installed can be easily determined. That is, since it is sufficient to arrange the LEDs between the electrodes that are not connected by the wirings 22a to 22i, it is convenient to form wirings in advance, especially when a large number of surge protection circuit portions 9α are formed. .

  The semiconductor element for surge protection according to the present invention is useful as a semiconductor element for surge protection that protects a plurality of LEDs from surges such as ESD.

(A) is a top view of the semiconductor element for surge protection which concerns on the 1st Embodiment of this invention, (b) is the sectional view on the A-A 'line of (a). The figure which shows an example of the LED package using the semiconductor element for surge protection of FIG. Circuit diagram of the semiconductor package shown in FIG. (A)-(d) is a figure for demonstrating the manufacturing method of the semiconductor element for surge protection of FIG. (E)-(f) is a continuation figure of FIG. (A) is the plane of the semiconductor element for surge protection which concerns on the 2nd Embodiment of this invention, (b) is the B-B 'sectional view taken on the line of (a). The figure which shows an example of the LED package using the semiconductor element for surge protection of FIG. Circuit diagram of the semiconductor package shown in FIG. Plan view of a semiconductor device for surge protection provided with nine surge protection circuit sections (A) is a figure which shows the conventional LED package, (b) is the circuit diagram. Expected view of LED package using conventional semiconductor device for surge protection Circuit diagram of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1a-1c Metal frame 2 N type semiconductor substrate 3 P type area | region 4 N type area | region 5 Insulating film 6a-6i Anode electrode 7a-7i Cathode electrode 8 Back surface electrodes 9a-9c Surge protection circuit part 10 Surge protection semiconductor element 11 LED Package 13 Sealing part 12a-12c LED
20 Surge protection semiconductor elements 22a to 22i Wiring 100 Surge protection semiconductor elements 101a and 101b Metal frame 102 N-type semiconductor substrate 103 P-type region 105 Insulating film 106 Cathode electrode 107 Anode electrode 108 Back electrode 120 LED

Claims (7)

A semiconductor device for surge protection provided with a Zener diode that is used by connecting in parallel elements to be protected from surge,
A first conductivity type semiconductor substrate;
A plurality of surge protection circuit units each including the Zener diode;
A back electrode formed on the back surface of the semiconductor substrate,
Each of the circuit portions for surge protection is
A second conductivity type region formed inside from the surface of the semiconductor substrate;
A first conductivity type region formed inside from the surface of the second conductivity type region;
An insulating film exposing a part of the first conductivity type region and a part of the second conductivity type region;
A first surface electrode formed in the first conductivity type region exposed from the insulating film;
And a second surface electrode formed in the second conductivity type region exposed from the insulating film.   The breakdown voltage of the Zener diode composed of the first conductivity type region and the second conductivity type region is larger than the voltage drop of the element to be protected during normal use, and the resistance of the element to be protected is 2. The semiconductor element for surge protection according to claim 1, wherein the semiconductor element is less than a voltage.   The semiconductor device for surge protection according to claim 2, wherein a breakdown voltage of the Zener diode is 3 to 50V.   The breakdown voltage of the isolation diode composed of the second conductivity type region and the semiconductor substrate is higher than the sum of the drop voltages of the elements to be protected during normal use. Surge protection semiconductor element.   5. The semiconductor device for surge protection according to claim 4, wherein a breakdown voltage of the isolation diode is 10 V or more.   By connecting the first surface electrode of the circuit portion for surge protection and the second surface electrode of another circuit portion for surge protection, wiring for connecting all the circuit portions for surge protection in series The semiconductor device for surge protection according to claim 1, further comprising: A method for manufacturing a semiconductor device for surge protection comprising a Zener diode for connecting elements to be protected from surge in parallel,
Forming a plurality of second conductivity type regions inside from the surface of the first conductivity type semiconductor substrate;
Forming a first conductivity type region from the surface of each second conductivity type region to the inside;
Forming an insulating film exposing a part of the first conductivity type region and a part of the second conductivity type region;
Forming first and second surface electrodes in the first conductivity type region and the second conductivity type region exposed from the insulating film;
And a step of forming a back electrode on the back surface of the semiconductor substrate.

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