JP2002313927A - Semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a semiconductor device in which initial resistance can be kept even if stress is applied by packaging and a conventionally required fuse is eliminated, a highly accurate breeder resistor circuit in which an accurate voltage division ratio can be kept, and a highly accurate semiconductor device using such a breeder resistor circuit, e.g. a voltage detector or a voltage regulator. SOLUTION: In a semiconductor device comprising a resistor, the resistor is formed by integrating a P type resistor formed of a P type semiconductor and an N type resistor formed of a N type semiconductor through an insulation film wherein the P type resistor is arranged on the low potential side and the N type resistor is arranged on the high potential side. The semiconductor device can be conducted by irradiating a P-N junction with a laser beam thereby destroying insulation properties. The current drive capacity of a driver MOS is enhanced by employing a thin P type polysilicon film having high impurity concentration equal to that of the contact region of a metal wire of the P type resistor in the gate electrode of an MOS transistor.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a semiconductor device, and more particularly to a semiconductor device having a resistor, a bleeder resistance circuit using the resistor, and a semiconductor device having the bleeder resistance circuit.

[0002]

2. Description of the Related Art Conventionally, a large number of resistors formed of a semiconductor thin film such as polysilicon and a bleeder resistor circuit using them have been used. What was formed by the thin film was known. The gate electrode of a MOS transistor is generally an N-type polysilicon thin film, and is a so-called same-polarity gate electrode which provides an N-type gate electrode for an NMOS and a P-type gate electrode for a PMOS in applications where performance is important. Was known. In addition, there has been known a method of obtaining a desired voltage division ratio by cutting a polysilicon fuse by laser trimming and changing the connection of a bleeder resistance circuit. Then, ICs such as a voltage detector and a voltage regulator have been manufactured using these.

[0003]

However, the conventional thin-film resistor changes its resistance value when a stress is applied to the thin-film resistor such as a resin package.
The bleeder resistance circuit has a problem that the voltage division ratio often fluctuates after the resin package. Further, in the conventional laser trimming method, it is necessary to provide a fuse for trimming with a laser beam in addition to the bleeder resistance circuit.

An object of the present invention is to solve the above problems and obtain a high-precision bleeder resistance circuit capable of maintaining an initial resistance value even after packaging and maintaining an accurate voltage division ratio in a bleeder resistance circuit. An object of the present invention is to provide a small and highly accurate semiconductor device, for example, a semiconductor device such as a voltage detector and a voltage regulator with high performance and low cost without installing a fuse which has been conventionally required.

[0005]

The first means adopted by the semiconductor device of the present invention to achieve the above object is that a resistor and a resistor of a bleeder resistor circuit using them are P-type semiconductors. The P-type resistor and the N-type resistor made of an N-type semiconductor are constituted. Further, in the bleeder resistance circuit, the resistance value as one unit is defined by a resistance value formed by combining a P-type resistor and an N-type resistor, so that a P-type resistor described below is provided. It is characterized in that a change in resistance value due to a piezo effect with an N-type resistor is offset each other.

The change in the resistance value due to the piezo effect and the effect on the bleeder resistance circuit will be described below.

When a stress is applied to the resistor, the resistance of the resistor changes due to the so-called piezo effect. However, the direction of the change in the resistance is different between the P-type resistor and the N-type resistor. Reverse. This has been confirmed by experiments performed by the present inventors. For example, the resistance value of the P-type resistor decreases, and the resistance value of the N-type resistor increases (the direction of the change depends on the direction of the stress).

[0008] When an IC is formed into a resin package, stress is generated, so that the resistance value of the resistor changes due to the piezo effect as described above. Although the bleeder resistance circuit is for obtaining an accurate voltage division ratio, the resistance value of each resistor changes, so that the voltage division ratio also fluctuates.

The resistor according to the present invention comprises a P-type resistor formed of a P-type semiconductor and an N-type resistor formed of an N-type semiconductor. The value can be prevented from changing. Also, in the bleeder resistance circuit, the resistance value as one unit is defined by the resistance value formed by combining the P-type resistor and the N-type resistor, so that even if stress is applied, The change in the resistance value of each resistor can be canceled out, and an accurate voltage division ratio can be maintained.

A second means adopted by the semiconductor device of the present invention to achieve the above object is that a P-type resistor is disposed on a low potential side and the N-type resistor is disposed on a high potential side, and an insulating film is formed on each other. And a current is not allowed to flow as it is. By irradiating a laser beam only to a necessary portion to the insulating film portion, the insulating property is broken to enable conduction. As a result, it is characterized in that the fuse which has been required conventionally is not required.

A third means adopted by the semiconductor device of the present invention to achieve the above object is to form a gate electrode of a MOS transistor and a P-type resistor by using the same polysilicon thin film and to form a P-type resistor. The high-concentration impurity region for making electrical connection with the metal wiring is formed of a polysilicon thin film having the same impurity and impurity concentration as the gate electrode of the MOS transistor. Thereby, the performance of the P-type MOS transistor can be improved at low cost without increasing the number of steps.

[0012]

The resistor of the semiconductor device according to the present invention is composed of a P-type resistor formed of a P-type semiconductor and an N-type resistor formed of an N-type semiconductor. Even when a stress is applied, for example, the change in the resistance value of each resistor can be canceled and the initial resistance value can be maintained.
In the bleeder resistance circuit, the resistance value as one unit is defined by a resistance value formed by combining a P-type resistor and an N-type resistor, so that an accurate voltage division ratio can be maintained. it can. In addition, the P-type resistor is disposed on the low potential side and the N-type resistor is disposed adjacent to the high potential side with an insulating film interposed therebetween. As a result, the fuse that has been required conventionally can be dispensed with. Further, the gate electrode of the MOS transistor and the P-type resistor are formed of the same polysilicon thin film, and the high-concentration impurity region for making electrical connection with the metal wiring of the P-type resistor is formed of the MOS transistor. Since the gate electrode is formed of a polysilicon thin film having the same impurity and impurity concentration as the gate electrode, the performance of the P-type MOS transistor can be improved without increasing the number of steps.

By using such a bleeder resistance circuit, a small and highly accurate semiconductor device, for example, a semiconductor device such as a voltage detector or a voltage regulator can be obtained.

[0014]

Preferred embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a schematic sectional view showing one embodiment of a polysilicon thin film resistor of a semiconductor device according to the present invention.

The first insulating film 10 is formed on the semiconductor substrate 101.
2 is formed, and a P-type polysilicon resistor 70 having a P-type high-resistance region 702 sandwiched between P-type low-resistance regions 701 containing a dense P-type impurity is formed on the first insulating film 102.
3 and an N-type low-resistance region 70 containing a dense N-type impurity
4 is an N-type polysilicon resistor 706 having an N-type high-resistance region 705 and one of the P-type low-resistance regions 701.
And one of the N-type low-resistance regions 704 has a thin insulating film 81.
5, a resistor 707 is formed in which a P-type polysilicon resistor 703 and an N-type polysilicon resistor 706 form a pair. The P-type low resistance region 701 on the side not in contact with the N-type polysilicon resistor 706 has a wiring 810 made of aluminum.
However, a wiring 811 made of aluminum is connected to the N-type low-resistance region 704 on the side not in contact with the P-type polysilicon resistor 703. Here, the wiring 810 is connected to, for example, the VSS side, the wiring 811 is connected to the VDD side, and the wiring 810 is connected to a lower potential than the wiring 811. Further, on the resistor 707, a protective film 813 made of a silicon nitride film or the like is irradiated with a laser beam to damage the insulating film 815 and remove the P-type low-resistance region 701. And one of the N-type low-resistance regions 704 is formed except for an area 814 where the low-resistance region 704 is in contact.

Here, the resistance value of the resistor 707 obtained by combining the P-type polysilicon resistor 703 and the N-type polysilicon resistor 706 is equal to that of the P-type polysilicon resistor 703 even when a stress is applied due to resin packaging or the like. Polysilicon resistor 703
And the change in the resistance value of the N-type polysilicon resistor 706 can be offset each other, so that the initial resistance value can be maintained.

FIG. 1 shows only an example in which one P-type polysilicon resistor 703 and one N-type polysilicon resistor 706 are combined, but the bleeder resistor circuit is composed of a plurality of P-type polysilicon resistors. 703 and an N-type polysilicon resistor 706.

A resistor 707 obtained by combining the P-type polysilicon resistor 703 and the N-type polysilicon resistor 706 shown in FIG. 1 is defined as one unit of a bleeder circuit, and a plurality of resistors 707 are provided. When the entire bleeder circuit is formed by individually forming the bleeder circuit, an accurate voltage division ratio can be maintained even when a stress is applied due to resin packaging or the like. By using such a bleeder resistance circuit, a highly accurate semiconductor device such as a semiconductor device such as a voltage detector or a voltage regulator can be obtained.

Further, FIG. 1 shows an example in which a polysilicon thin film resistor is used, but the present invention is not limited to this. For example, a single crystal thin film resistor or a diffusion resistor formed in a silicon substrate may be used. For example, it is applicable if the P-type and N-type resistors can be integrally formed.

Further, according to the embodiment shown in FIG. 1, in order to obtain a desired voltage division ratio of the bleeder resistance circuit, the resistor 7
Since it is sufficient to perform laser trimming on 07, a fuse for cutting by a laser beam, which has been conventionally required, is not required. In the embodiment shown in FIG. 1, a protective film 813 made of a silicon nitride film or the like is provided on the resistor 707 to irradiate a laser beam to damage the insulating film 815 and remove the insulating property.
One of the P-type low-resistance regions 701 and the N-type low-resistance region 70
4 is formed except for an area 814 in contact with one of the P-type low-resistance regions 701 if the insulating property can be broken by a laser beam even when the protective film 813 exists. The protective film 813 may be formed also on an area 814 where one of the N-type and one of the N-type low-resistance regions 704 is in contact.

Although not shown, the gate electrode of the MOS transistor mounted on the same chip as the resistor 707 is formed of the same polysilicon thin film as the P-type polysilicon resistor 703. Further, the gate electrode of the MOS transistor has the same impurity and impurity concentration as the P-type low-resistance region 701 containing the heavy P-type impurity.
A P-type low-resistance region 70 in the P-type polysilicon resistor 703.
Exactly the same as 1. Therefore, it is possible to form a gate electrode having a P-type impurity which is particularly suitable for improving the performance of a P-type MOS transistor without increasing the number of special steps. At this time, the performance of the N-type MOS transistor may slightly decrease, but in the case of a power control IC such as a voltage regulator as described later, in most cases, the P-type MOS transistor is used.
This is often more convenient because an S transistor is used as a driver transistor.

FIG. 2 is a block diagram of an embodiment of a voltage detector using a bleeder resistance circuit according to the present invention.

Although an example of a simple circuit is shown for simplicity, functions may be added to an actual product as needed.

The basic circuit components of the voltage detector are a current source 903, a reference voltage circuit 901, a bleeder resistance circuit 902, and an error amplifier 904. In addition, an inverter 906, N-type transistors 905 and 908, a P-type transistor 907, and the like. Has been added. A part of the operation will be briefly described below.

When VDD is equal to or higher than a predetermined release voltage, the N-type transistors 905 and 908 are turned off, the P-type transistor 907 is turned on, and VDD is output to the output OUT. At this time, the input voltage of the error amplifier 904 is (RB +
RC) / (RA + RB + RC) * VDD.

When VDD drops and becomes equal to or lower than the detection voltage, VSS is output to the output OUT. At this time, the N-type transistor 905 is ON, and the input voltage of the error amplifier 904 is R
B / (RA + RB) * VDD.

As described above, the basic operation is based on the reference voltage generated by the reference voltage circuit 901 and the bleeder resistance circuit 90.
This is performed by comparing the voltage divided by 2 with the error amplifier 904. Therefore, the accuracy of the voltage divided by the bleeder resistance circuit 902 is extremely important. If the voltage division accuracy of the bleeder resistance circuit 902 is poor, the error amplifier 904
Input voltage varies, and a predetermined release or detection voltage cannot be obtained. By using the bleeder resistance circuit according to the present invention, high-precision voltage division is possible even after the IC is resin-packaged, so that the product yield as an IC can be improved or a more accurate voltage detector can be manufactured. Become.

FIG. 3 is a block diagram of an embodiment of a voltage regulator using a bleeder resistance circuit according to the present invention.

Although an example of a simple circuit is shown for simplicity, functions may be added to an actual product as needed.

Basic circuit components of the voltage regulator include a current source 903, a reference voltage circuit 901, a bleeder resistance circuit 902, an error amplifier 904, and a P-type transistor 910 functioning as a current control transistor. A part of the operation will be briefly described below.

The error amplifier 904 compares the voltage divided by the bleeder resistance circuit 902 with the reference voltage generated by the reference voltage circuit 901, and outputs a constant output voltage VOUT which is not affected by the input voltage VIN or temperature change. The gate voltage required to obtain the voltage is supplied to the P-type transistor 910. Similar to the case of the voltage detector described with reference to FIG. 2, the basic operation of the voltage regulator is similar to that of the error detector 90 in which the reference voltage generated by the reference voltage circuit 901 and the voltage divided by the bleeder resistance circuit 902 are used.
This is done by comparison at 4. Therefore, the accuracy of the voltage divided by the bleeder resistance circuit 902 is extremely important. If the voltage division accuracy of the bleeder resistance circuit 902 is poor, the input voltage to the error amplifier 904 varies, and a predetermined output voltage VOUT cannot be obtained. By using the bleeder resistance circuit according to the present invention, high-precision voltage division is possible even after the IC is resin-packaged, so that the product yield as an IC can be improved and a more accurate voltage regulator can be manufactured. Become.

The P-type transistor 910 is generally called a driver transistor, and requires a high current driving capability. In the present invention, since a P-type polysilicon thin film having a high impurity concentration is used as a gate electrode, a surface channel type device can be provided, and the gate length of a transistor (so-called L length) for suppressing a constant leakage current can be obtained. ) Can be made shorter than that of a general P-type MOS transistor having a gate electrode of an N-type polysilicon thin film. Therefore, high current driving capability can be exhibited.

[0034]

As described above, the thin film resistor of the semiconductor device according to the present invention includes a P-type thin film resistor formed of a P-type semiconductor thin film and an N-type thin film resistor formed of an N-type semiconductor thin film. Since it is composed of a body, even if a stress is applied due to resin packaging or the like, it is possible to cancel the change in the resistance value of each resistor and maintain the initial resistance value. In the bleeder resistance circuit, the resistance value of one unit is P
Since the resistance is determined by the resistance value formed by combining the N-type thin film resistor and the N-type thin film resistor, an accurate voltage division ratio can be maintained. In addition, the P-type resistor is disposed on the high potential side, and the N-type resistor is disposed on the low potential side. By irradiating a laser beam or the like to the insulating film portion, the insulating property is broken to enable conduction. As a result, the conventionally required fuse can be eliminated. In addition, the current driving capability of the driver transistor, which is a P-type MOS transistor, can be improved without any special steps.

By using such a bleeder resistance circuit, there is an effect that a small and highly accurate semiconductor device, for example, a semiconductor device such as a voltage detector or a voltage regulator can be obtained.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing one embodiment of a semiconductor thin film resistor of a semiconductor device of the present invention.

FIG. 2 is a block diagram of an embodiment of a voltage detector using a bleeder resistance circuit according to the present invention.

FIG. 3 is a block diagram of an embodiment of a voltage regulator using a bleeder resistance circuit according to the present invention.

DESCRIPTION OF SYMBOLS 101 Semiconductor substrate 102 First insulating film 701 P-type low-resistance region 702 P-type high-resistance region 703 P-type polysilicon resistor 704 N-type low-resistance region 705 N-type high-resistance region 706 N-type polysilicon resistor 707 Resistor 801 Second insulating film 810 Wiring 811 Wiring 814 Area where one of P-type low-resistance regions 701 contacts one of N-type low-resistance regions 704 815 Insulating film 901 Reference voltage circuit 902 bleeder resistance circuit 903 current source 904 error amplifier 905 N-type transistor 906 inverter 907 P-type transistor 908 N-type transistor 909 parasitic diode 910 P-type transistor

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5F038 AR09 AR13 BB08 BB09 EZ20

Claims (5)

[Claims] 1. A semiconductor device having a MOS transistor and a resistor, wherein the resistor is a P-type resistor formed of a P-type semiconductor and an N-type resistor formed of an N-type semiconductor. Are disposed adjacent to each other with an insulating film interposed therebetween,
The P-type resistor is disposed on the low potential side, and the N-type resistor is disposed on the high potential side. By irradiating the insulating film portion with a laser beam or the like, the insulating property is broken to enable conduction. A semiconductor device characterized in that: 2. The semiconductor device according to claim 1, wherein said resistor is formed of a polysilicon thin film. 3. The gate electrode of the MOS transistor and the P-type resistor are formed of the same polysilicon thin film, and have a high concentration for making electrical connection with a metal wiring of the P-type resistor. 2. The semiconductor device according to claim 1, wherein the impurity region is formed of a polysilicon thin film having the same impurity and impurity concentration as the gate electrode of the MOS transistor. 4. The semiconductor device according to claim 1, wherein said semiconductor device is a voltage detector. 5. The semiconductor device according to claim 1, wherein said semiconductor device is a voltage regulator.