JP4717246B2 - Semiconductor device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a semiconductor device, in particular, a semiconductor device having a resistor, a bleeder resistance circuit using the resistor, and a semiconductor device having the bleeder resistance circuit.
[0002]
[Prior art]
Conventionally, many resistors formed of semiconductor thin films such as polysilicon and bleeder resistor circuits using them have been used, but they were formed of either N-type or P-type semiconductor thin films. Things were known. The gate electrode of the MOS transistor is generally an N-type polysilicon thin film, and so-called a homopolar gate electrode that provides an N-type gate electrode for NMOS and a P-type gate electrode for PMOS for some performance-oriented applications. Was known. Further, there has been known a method of obtaining a desired voltage division ratio by cutting a polysilicon fuse by laser trimming to change connection of a bleeder resistance circuit. And ICs such as a voltage detector and a voltage regulator have been made using these.
[0003]
[Problems to be solved by the invention]
However, the resistance value of a conventional thin film resistor changes when a stress is applied to the thin film resistor, such as when it is made into a resin package. In a bleeder resistor circuit, the voltage dividing ratio often fluctuates after the resin package. There was a problem that it was. Further, in the conventional laser trimming method, it is necessary to provide a fuse for trimming with a laser beam in addition to a bleeder resistance circuit.
[0004]
The present invention eliminates the above-described problems, and obtains a highly accurate bleeder resistance circuit that retains an initial resistance value after packaging and can maintain an accurate voltage dividing ratio in the bleeder resistance circuit. It is an object of the present invention to provide a small and highly accurate semiconductor device such as a voltage detector and a voltage regulator with high performance and low cost without installing a fuse.
[0005]
[Means for Solving the Problems]
The first means employed by the semiconductor device of the present invention to achieve the above object is that the resistor and the resistor of the bleeder resistance circuit using them are a P-type resistor formed of a P-type semiconductor, And an N-type resistor formed of an N-type semiconductor. Further, 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 the P-type resistor described below, It is characterized in that the change in resistance value due to the piezo effect with the N-type resistor cancels each other.
[0006]
The following describes the change in resistance due to the piezo effect and the effect on the bleeder resistance circuit.
[0007]
When stress is applied to the resistor, the resistance value of the resistor changes due to the so-called piezo effect, but the direction of change in resistance value is reversed between the P-type resistor and the N-type resistor. . This has also been confirmed by experiments of 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 change varies depending on the direction of stress).
[0008]
Since stress is generated when the IC is packaged in a resin package, the resistance value of the resistor changes due to the piezoelectric effect as described above. The bleeder resistance circuit is used to obtain an accurate voltage dividing ratio. However, since the resistance value of each resistor changes, the voltage dividing ratio also varies.
[0009]
Since the resistor 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, the resistance value changes even when stress is applied. Can be prevented. 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 even if stress is applied, It is possible to cancel changes in the resistance values of individual resistors and maintain an accurate voltage division ratio.
[0010]
The second means employed by the semiconductor device of the present invention to achieve the above object is that the P-type resistor is disposed on the low potential side and the N-type resistor is disposed on the high potential side, and separated from each other by an insulating film. In this state, a current does not flow, and only a necessary portion is irradiated with a laser beam on the insulating film portion, thereby destroying the insulating property and enabling conduction. As a result, a fuse that has been conventionally required is unnecessary.
[0011]
The third means employed by the semiconductor device of the present invention to achieve the above object is that the gate electrode of the MOS transistor and the P-type resistor are formed of the same polysilicon thin film, and the metal wiring of the P-type resistor The high-concentration impurity region for the electrical connection 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 processes.
[0012]
[Action]
The resistor of the semiconductor device of 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 the resistance is applied, it is possible to cancel the resistance value changes of the individual resistors and maintain the initial resistance value. 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 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 via an insulating film, and the insulating film is destroyed by irradiating the insulating film portion with a laser beam or the like. Therefore, it is possible to eliminate the need for a fuse which has been conventionally required. Further, the MOS transistor has a gate electrode and a P-type resistor formed of the same polysilicon thin film, and a high-concentration impurity region for electrical connection with the metal wiring of the P-type resistor Since the gate electrode is formed of a polysilicon thin film having the same impurity and impurity concentration, the performance of the P-type MOS transistor can be improved without increasing the number of steps.
[0013]
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]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.
[0015]
FIG. 1 is a schematic cross-sectional view showing one embodiment of a polysilicon thin film resistor of a semiconductor device of the present invention.
[0016]
A first insulating film 102 is formed on the semiconductor substrate 101, and a P-type high-resistance region sandwiched between P-type low-resistance regions 701 containing a dense P-type impurity is formed on the first insulating film 102. A P-type polysilicon resistor 703 having 702 and an N-type polysilicon resistor 706 having an N-type high-resistance region 705 sandwiched between N-type low-resistance regions 704 containing dense N-type impurities are P-type. One of the low-resistance regions 701 and one of the N-type low-resistance regions 704 are arranged so as to be in contact with each other through a thin insulating film 815, and the P-type polysilicon resistor 703 and the N-type polysilicon resistor 706 are 1 A pair of resistors 707 is formed. Also, in the P-type low resistance region 701 on the side not in contact with the N-type polysilicon resistor 706, a wiring 810 made of aluminum is also provided on the side not in contact with the P-type polysilicon resistor 703. A wiring 811 made of aluminum is connected to the low resistance region 704. Here, for example, the wiring 810 is connected to the VSS side and the wiring 811 is connected to the VDD side, and the wiring 810 is connected to a potential lower than that of the wiring 811. Further, on the resistor 707, a protective film 813 made of a silicon nitride film or the like irradiates a laser beam, damages the insulating film 815, and eliminates the insulating property. And one of the N-type low-resistance regions 704 are formed except on the area 814.
[0017]
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 the P-type polysilicon resistance even when stress is applied due to resin packaging or the like. Since the change in resistance value of the body 703 and the change in resistance value of the N-type polysilicon resistor 706 can be canceled out, the initial resistance value can be maintained.
[0018]
Although FIG. 1 shows only an example in which one P-type polysilicon resistor 703 and one N-type polysilicon resistor 706 are combined, the bleeder resistor circuit includes a plurality of P-type polysilicon resistors 703 and N The resistor 707 is obtained by combining the type polysilicon resistor 706.
[0019]
Further, 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 the bleeder circuit, and a plurality of resistors 707 are formed. If the entire bleeder circuit is configured, an accurate voltage division ratio can be maintained even when stress is applied due to resin packaging. By using such a bleeder resistance circuit, a highly accurate semiconductor device, for example, a semiconductor device such as a voltage detector or a voltage regulator can be obtained.
[0020]
Further, although an example using a polysilicon thin film resistor is shown in FIG. 1, the present invention is not limited to this, and a single crystal thin film resistor, a diffusion resistor formed in a silicon substrate, etc. The present invention is applicable if the mold and the N-type resistor can be formed integrally.
[0021]
Further, according to the embodiment shown in FIG. 1, laser trimming may be performed on the resistor 707 in order to obtain a desired voltage dividing ratio of the bleeder resistance circuit. A fuse for cutting by is not required. In the embodiment of FIG. 1, a protective film 813 made of a silicon nitride film or the like is irradiated on the resistor 707 with a laser beam to damage the insulating film 815 and eliminate insulation. It is formed except on the area 814 where one of the P-type low-resistance regions 701 and one of the N-type low-resistance regions 704 are in contact with each other. In this case, the protective film 813 may be formed also on the area 814 where one of the P-type low resistance regions 701 and one of the N-type low resistance regions 704 are in contact with each other.
[0022]
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 is a P-type polysilicon thin film having the same impurity and impurity concentration as the P-type low-resistance region 701 containing a dense P-type impurity. This is exactly the same as the P-type low resistance region 701 in 703. Therefore, it is possible to form a gate electrode having a P-type impurity suitable for improving the performance of the P-type MOS transistor without increasing the number of special steps. In this case, the performance of the N-type MOS transistor may be slightly reduced. However, as will be described later, in the case of a power supply control IC such as a voltage regulator, in most cases, a P-type MOS transistor is used as a driver transistor. This is often more convenient.
[0023]
FIG. 2 is a block diagram of an embodiment of a voltage detector using a bleeder resistance circuit according to the present invention.
[0024]
For simplicity, an example of a simple circuit is shown. However, functions may be added to actual products as necessary.
[0025]
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 are added. Yes. A part of the operation will be briefly described below.
[0026]
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.
[0027]
When VDD falls below 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 RB / (RA + RB) * VDD.
[0028]
Thus, the basic operation is performed by comparing the reference voltage generated by the reference voltage circuit 901 with the voltage divided by the bleeder resistance circuit 902 by the error amplifier 904. Therefore, the accuracy of the voltage divided by the bleeder resistance circuit 902 is extremely important. If the voltage dividing accuracy of the bleeder resistance circuit 902 is poor, the input voltage to the error amplifier 904 varies, and a predetermined release or detection voltage cannot be obtained. By using the bleeder resistance circuit according to the present invention, it is possible to perform high-precision voltage division even after resin packaging of the IC, so that the product yield as an IC can be improved and a more accurate voltage detector can be manufactured. Become.
[0029]
FIG. 3 is a block diagram of an embodiment of a voltage regulator using a bleeder resistance circuit according to the present invention.
[0030]
For simplicity, an example of a simple circuit is shown. However, functions may be added to actual products as necessary.
[0031]
The basic circuit components of the voltage regulator are a current source 903, a reference voltage circuit 901, a bleeder resistance circuit 902, an error amplifier 904, and a P-type transistor 910 that functions as a current control transistor. A part of the operation will be briefly described below.
[0032]
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 obtains a constant output voltage VOUT that is not affected by the input voltage VIN or temperature change. A necessary gate voltage is supplied to the P-type transistor 910. In the voltage regulator, as in the case of the voltage detector described with reference to FIG. 2, the basic operation is to compare the reference voltage generated by the reference voltage circuit 901 with the voltage divided by the bleeder resistance circuit 902 by the error amplifier 904. Is done. Therefore, the accuracy of the voltage divided by the bleeder resistance circuit 902 is extremely important. If the voltage dividing 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. The use of the bleeder resistance circuit according to the present invention enables high-precision voltage division even after resin packaging of the IC, thereby improving the product yield as an IC and making it possible to manufacture a higher-precision voltage regulator. Become.
[0033]
The P-type transistor 910 is generally called a driver transistor, and requires a high current driving capability. In the present invention, since a polysilicon thin film having a high P-type impurity concentration is used as the gate electrode, a surface channel type device can be obtained, and the transistor gate length (so-called L length) for suppressing a constant leakage current can be obtained. ) Can be shortened as compared with a P-type MOS transistor having a gate electrode of a general N-type polysilicon thin film. Therefore, a high current driving capability can be exhibited.
[0034]
【The invention's effect】
As described above, the thin film resistor of the semiconductor device of the present invention is composed of 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. Therefore, even when stress is applied due to resin packaging or the like, it is possible to cancel the resistance value change of each resistor and to maintain the initial resistance value. Further, in the bleeder resistance circuit, the resistance value as one unit is defined by the resistance value formed by combining the P-type thin film resistor and the N-type thin film resistor, so that an accurate voltage dividing ratio is maintained. be able to. Further, the P-type resistor is arranged on the high potential side, the N-type resistor is arranged on the low potential side, and the insulating film portion is irradiated with a laser beam or the like so that the insulation is destroyed and conduction is enabled. As a result, it is possible to eliminate the need for a fuse that has been conventionally required. Further, the current driving capability of the driver transistor, which is a P-type MOS transistor, can be improved without any special process increase.
[0035]
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 cross-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.
[Explanation 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 resistance Body 707 Resistor 801 Second insulating film 810 Wiring 811 Wiring 814 Area 815 where one of P-type low resistance region 701 and one of N-type low resistance region 704 are in contact 815 Insulating film 901 Reference voltage circuit 902 Breeder 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

Claims (5)

In a semiconductor device having a MOS transistor and a resistor, the resistor includes an insulating film formed by a P-type resistor formed of a P-type semiconductor and an N-type resistor formed of an N-type semiconductor. The P-type resistor is arranged on the low potential side and the N-type resistor is arranged on the high potential side, and the insulating film portion is irradiated by irradiating it with a laser beam or the like. A semiconductor device characterized in that the electrical property is destroyed and conduction is enabled. The semiconductor device according to claim 1, wherein the resistor is formed of a polysilicon thin film. 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 electrical connection with the metal wiring of the P-type resistor is 2. The semiconductor device according to claim 1, wherein the semiconductor device is formed of a polysilicon thin film having the same impurity and impurity concentration as the gate electrode of the MOS transistor. The semiconductor device according to claim 1, wherein the semiconductor device is a voltage detector. The semiconductor device according to claim 1, wherein the semiconductor device is a voltage regulator.

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