JP5959254B2 - Semiconductor device - Google Patents

Description

  The present invention relates to a semiconductor device having a resistance element made of a vertical resistor.

  A resistor made of polycrystalline silicon into which impurities are implanted is often used as a resistance element of a semiconductor device. FIG. 2 shows a conventional semiconductor device having a resistance element. This semiconductor device includes a MOS transistor region on the left side of the drawing and a resistance element region on the right side. In the left MOS transistor region, a MOS transistor including a gate electrode 4, a source region 5, a drain region 6, and a conductive metal wiring 8 connected to them is formed. Further, in the resistance element region on the right side, an insulating film 7 such as BPSG is formed on the field oxide film 2 on the semiconductor substrate 1, and a laminated film 12 of polycrystalline silicon is formed on the insulating film 7 so as to reduce the thin film resistance. There is no. Conductive metal wiring 8 is provided as an electrode in the thin film resistor. (For example, see Patent Document 1)

Japanese Patent Laid-Open No. 2-312267

  In general, a resistance element is required to have a high ratio accuracy representing the relative accuracy of the resistance elements in a single semiconductor device, so that the geometric size of the resistance element is sufficiently small to match the processing accuracy. However, the area occupied by the resistance element in the semiconductor device is large. Accordingly, an object of the present invention is to reduce the size of a semiconductor device by reducing the resistance element region.

In order to solve the above problems, the following means were used.
First, a semiconductor device having a semiconductor substrate and a resistive element provided thereon,
The resistance element is
A lower electrode provided above the surface of the semiconductor substrate via a first insulating film;
Two upper layer electrodes provided above the lower electrode and spaced apart from each other through the second insulating film, and further spaced apart from each other on the second insulating film;
Two vertical resistors having a hollow interior and disposed inside the second insulating film, each having an upper end junction and a lower end junction connected to the lower layer electrode and the two upper layer electrodes, respectively; ,
Consists of
The upper end joint has a shape extending outward from the cylindrical side surface below it,
The lower end joint portion is a bottom surface that covers the bottom of the cylinder.

The vertical resistor is a semiconductor device characterized in that a third insulating film is filled in the center.
The vertical resistor has a concentric shape when viewed from the extended line of the central axis.
Further, the semiconductor device is characterized in that the vertical resistor is made of any one of tungsten silicide, chromium silicide, molybdenum silicide, nichrome, titanium, and polycrystalline silicon.
In addition, a semiconductor device is characterized in that the vertical resistor is polycrystalline silicon, and the upper end junction portion contains a high concentration of impurities.

By using the above structure, a vertically long resistor having electrodes on the upper and lower sides can be formed in the contact hole, so that the area occupied by the resistor element can be reduced and the semiconductor device can be miniaturized.
Also, since the resistor is created on the side surface of the cylinder, unlike the side surface of the prism, it can be formed with the same thickness on the circumference. Can be used as a few vertical resistors.

1 is a schematic cross-sectional view of a MOS transistor having a resistor structure according to the present invention. It is a schematic cross section of the semiconductor MOS type transistor which has the structure of the thin film resistance of a prior art.

Hereinafter, the structure of a semiconductor having a resistance element according to the present invention will be described with reference to the drawings.
FIG. 1 is a schematic cross-sectional view showing a first embodiment of a MOS transistor having a resistor structure according to the present invention. The semiconductor device shown has a MOS transistor and a vertical resistor on the surface of a semiconductor silicon substrate.

First, the region where the MOS transistor is formed will be described. A P-type conductivity semiconductor silicon substrate 1 surface, the field oxide film 2 for element isolation formed by LOCOS (Loc al O xidation of S ilicon) method are provided. The region where the MOS transistor is formed is a region without the field oxide film 2, and the gate electrode 4 is provided on the semiconductor silicon substrate via the gate oxide film 3. Usually, the gate electrode is made of a material mainly composed of other crystalline silicon or polycrystalline silicon. The upper surface and side surfaces of the gate electrode 4 are covered with a first insulating film 7, and a source region 5 and a drain region 6 are formed on the surface of the semiconductor silicon substrate 1 on both sides of the gate electrode 4. The source region 5 and the drain region 6 are provided so as to penetrate one end of the first metal wiring 8 through the first insulating film, and function as a source electrode and a drain electrode, respectively. The other end of the first metal wiring 8 is on the first insulating film 7 and is in contact with the upper second metal wiring 11c. A second insulating film 9 is provided between the first metal wiring 8 and the second metal wiring 11c.

Next, the structure of the region where the vertical resistor is arranged will be described. A first insulating film 7 is provided on the field oxide film 2, a first metal wiring 8 is formed on the first insulating film 7, and a first metal wiring film 8 is formed on the first metal wiring film 8. Two insulating films 9 and a second metal wiring 11 are provided in this order. Between the first metal wiring 8 and the second metal wiring 11, the inside of the contact hole 13 provided through the second insulating film 9, the inside having a bottom 15 and a hollow cylindrical shape is formed. Vertical resistors 10a and 10b made of a thin film of high-resistance polycrystalline silicon are disposed. Vertical resistor 10a, the upper end of the 10b are therefore wide outwardly from the side surface of the cylinder having a substantially uniform diameter of the lower, and has a upper joint 10c. The upper end joint portion 10c is connected to the second metal wires 11a and 11b which are spaced apart from each other, and the bottom surface which is the lower end covers the bottom of the cylinder and is connected to the first metal wire 8 together.

  The reason why the upper ends of the vertical resistors 10a and 10b are formed as upper end joints 10c spreading outward is to increase the cross-sectional area and reduce the resistance due to the connection with the second metal wirings 11a and 11b. . When the vertical resistor is polycrystalline silicon, high-concentration impurities may be ion-implanted into the upper junction to form a low resistance region. Both lower ends 10a and 10b are connected to the first metal wiring 8. In the figure, two vertical resistors 10a and 10b are shown, each connected at the lower end, but this has a cylindrical shape in which the thin vertical resistor has a bottom surface 15. Since the cross section is shown, the two resistive elements that appear to be two are continuous thin films. The vertical resistors 10 a and 10 b are cylindrical and are formed in a thin film shape along the inner wall surface and the bottom surface of the contact hole 13. The lower end joint portion forms a bottom surface that covers the bottom of the cylinder. Like the upper end joint portion 10c of the vertical resistor, the cross-sectional area is large, so that the resistance due to connection is low. A cylindrical third insulating film 16 is filled in the center of each of the thin vertical resistors 10a and 10b. When the vertical resistor is viewed from an extension of the central axis, it has a concentric shape. By adopting such a shape, a vertical resistor with a small resistance change with respect to a temperature change and a small occupation area can be obtained.

  The material of the resistor may be selected from any one of tungsten silicide, chromium silicide, molybdenum silicide, nichrome, and titanium in addition to conductive high-resistance polycrystalline silicon.

DESCRIPTION OF SYMBOLS 1 Semiconductor silicon substrate 2 Field oxide film 3 Gate oxide film 4 Gate electrode 5 Source region 6 Drain region 7 First insulating film 8 First metal wiring 9 Second insulating film 10a, 10b Vertical resistor 10c Vertical resistor Upper end joints 11a, 11b, 11c of the body Second metal wiring 12 Polycrystalline silicon thin film resistor 13 Contact hole 15 Bottom surface 16 Third insulating film

Claims (5)

A semiconductor device having a semiconductor substrate and a resistive element provided thereon,
The resistance element is
A lower electrode provided above the surface of the semiconductor substrate via a first insulating film;
Two upper layer electrodes provided above the lower electrode and spaced apart from each other through the second insulating film, and further spaced apart from each other on the second insulating film;
Two vertical resistors having a hollow interior and disposed inside the second insulating film, each having an upper end junction and a lower end junction connected to the lower layer electrode and the two upper layer electrodes, respectively; ,
Consists of
The upper end joint has a shape extending outward from the cylindrical side surface below, and the cross-sectional area of the upper end joint is larger than the lower cross-sectional area of the upper end joint ,
The semiconductor device according to claim 1, wherein the lower end joint portion is a bottom surface that covers the bottom of the cylinder.   The semiconductor device according to claim 1, wherein the vertical resistor is filled with a third insulating film in the center.   3. The semiconductor device according to claim 2, wherein the vertical resistor has a concentric shape when viewed from an extended line of a central axis.   3. The semiconductor device according to claim 2, wherein the vertical resistor is made of any one of tungsten silicide, chromium silicide, molybdenum silicide, nichrome, titanium, and polycrystalline silicon.   3. The semiconductor device according to claim 2, wherein the vertical resistor is polycrystalline silicon, and the upper end junction includes a high concentration of impurities.

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