JPS6236396B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a resistor for a semiconductor integrated circuit device and a method for manufacturing the same.

2. Description of the Related Art In semiconductor integrated circuit devices, a resistor made of polycrystalline silicone that does not contain impurities or contains only a trace amount of impurities is used as a resistor that has a high layer resistance value within a small area.

Conventional resistors of this type have been made of crystalline silicon having one type of layer resistance value. In addition, the manufacturing method involves first forming a wiring part and a resistor part at the same time in polycrystalline silicon using a photo-etching process, and then using a photo-etching process to form a mask for adding impurities over the part that will become the resistor. Then, when impurities are added, the impurities are added to the polycrystalline silicon in the wiring area at a high concentration, and the polycrystalline silicon under the mask area is not doped with impurities and becomes a resistor with a high resistance value. Become.

According to this prior art, in order to obtain two or more types of resistance values, the length or width of the resistor must be changed. Especially when trying to form two or more resistors with significantly different resistance values, the width of the resistor with the lower resistance value must be increased and the length of the resistor with the higher resistance value must be increased. This has been an obstacle to reducing the area of semiconductor integrated circuit devices.

An object of the present invention is to reduce the area required for the resistors and increase the degree of integration in a semiconductor integrated circuit device having two or more types of resistors having different resistance values.

The semiconductor integrated circuit device of the present invention is characterized by comprising two or more types of high resistance bodies made of polycrystalline silicon having different layer resistance values.

The method for manufacturing a semiconductor integrated circuit device of the present invention includes the steps of forming a plurality of polycrystalline silicon patterns containing impurities at a constant concentration on a semiconductor substrate via an insulating film, and forming the surface of the polycrystalline silicon with different thicknesses. This method is characterized by including a step of forming two or more types of resistors having different layer resistance values by slight oxidation.

According to the present invention, many types of resistors with different resistance values can be obtained by simply changing the layer resistance value, so there is no need to change the length or width of the resistor, and the area required for the resistor can be reduced. Therefore, the degree of integration of the semiconductor integrated circuit device can be improved.

EMBODIMENT OF THE INVENTION Hereinafter, as an example of the present invention, a semiconductor integrated circuit including three types of resistors having different layer resistance values will be described with reference to the drawings.

First, as shown in FIG. 1, a field insulating film 2 is formed on a silicon substrate 1, and polycrystalline silicon 3 is deposited on the entire surface thereof by chemical vapor deposition. Thereafter, impurities are added so that this polycrystalline silicon has a layer resistance necessary to form a resistor with the highest layer resistance value. In this case, when polycrystalline silicon is grown by chemical vapor deposition, impurities may be added to the source gas to deposit polycrystalline silicon having a desired layer resistance.

Thereafter, as shown in FIG. 2, the polycrystalline silicon is patterned using a photolithography process to
A wiring 5 including a portion to become a resistor portion is formed. In this case, the polycrystalline silicon of the gate portion may be formed at the same time.

Next, as shown in FIG. 3, a thermal oxidation mask (SiO ₂ ) 6 is formed on the portions of the polycrystalline silicon 5 where all the resistors will be formed. In this case, the portions other than the mask 6 are covered with an oxide resistant material 7 (for example, a silicon nitride film), and the polycrystalline silicon is oxidized only in the mask 6 portions. The oxide film needs to be thick enough to prevent the polycrystalline silicon under the mask 6 from being doped with impurities when the wiring polycrystalline silicon is doped with impurities in a later step. The impurity concentration of the polycrystalline silicon is set such that the layer resistance value of the resistor formed by the mask 6 is the highest layer resistance value among the various layer resistance values to be created. In addition, the resistor with the highest layer resistance value is 8, the resistor with the second highest layer resistance value is 9,
The resistor having the third highest layer resistance value is designated as 10.

Next, as shown in FIG. 4, the oxide resistor 7 is removed, and the same oxide resistor 7 is applied to the parts other than the resistor 9 having the second highest layer resistance value and the resistor 10 having the third highest layer resistance value. oxidation-resistant material 11 is formed. Thereafter, when thermal oxidation is performed, the polycrystalline silicon of the resistors 9 and 10 is thermally oxidized, and the thickness of the thermal oxide film 12 increases. At this time, impurity segregation progresses in the polycrystalline silicon of the resistors 9 and 10, and the layer resistance value becomes smaller than that of the resistor 8. this is,
Since the impurities do not enter SiO ₂ and segregate in the polycrystalline silicon, there are parts of the polycrystalline silicon near the interface with the oxide film in the resistors 9 and 10 where the impurity concentration is higher than other parts. Since that portion becomes a factor that determines the layer resistance value, the layer resistance value decreases.

Next, as shown in FIG. 5, as in the previous step, the oxide resistant material 11 is removed, and an oxidized resistant material 13 similar to the oxidized material 7 is formed in the area other than the resistor 10 having the third highest layer resistance value. do. Thereafter, when thermal oxidation is performed, the polycrystalline silicon of the resistor 10 is thermally oxidized, and the thickness of the thermal oxide film 14 increases. At this time, resistor 10
Segregation of impurities progresses in the polycrystalline silicon of the resistor 9, and the layer resistance value becomes smaller than that of the resistor 9.

After that, as shown in FIG. 6, the oxide resistor 13 is removed and the polycrystalline silicon is doped with impurities.
The resistor elements 8, 9, 10 are covered with masks 6, 1, respectively.
2 and 14, the impurity is not doped into the other portions and becomes a wiring portion.

In the above example, for example, 1×10 ¹⁴ atoms/cm ² of phosphorus was added as an impurity into polycrystalline silicon, and the thickness of the polycrystalline silicon oxide film was increased to 3000 Å.
When using three types of 5000 Å and 9000 Å, the respective layer resistance values are 500 to 1000 kΩ/mouth and 50 to 100 kΩ/
mouth, 5-10 kΩ/mouth is obtained. In this case, when the thickness of polycrystalline silicon is 6000 Å, the length is 10 μm, and the width is 5 μm, the resistance value is 1 to 2 M.
Ω, 100 to 200kΩ, and 10k to 20kΩ.

In this example, each time the oxidation process is repeated, the oxidation resistant material is removed and the oxidation resistant material is deposited again.
Other methods, such as a photo-etching process, first remove and oxidize the oxidation resistant material on the part of the resistor that has the lowest resistance value, and then oxidize the oxidation resistant material on the part of the resistor that has the second lowest resistance value. Even if the oxidation-resistant material is removed and oxidized in order from the portion of the resistor where the resistance value decreases, the same result as in the example can be obtained.

Note that although the case of manufacturing a resistor having three types of layer resistance values has been described here, when manufacturing a resistor having two types of layer resistance values, the process explained in FIG. 5 may be omitted. . Also, the layer resistance value is 4
In the case of manufacturing a resistor having more than one type of resistance value, it is possible to manufacture the resistor by changing the resistor covered with the oxide resistant material and adding the process explained in FIG. 5.

Further, although the portion under the polycrystalline silicon is made into a field insulating film, the effect of the present invention is not affected even if there is an element or wiring under the insulating film.
Furthermore, the effects of the present invention are the same for polycrystalline silicon formed on an insulating substrate.

As described above, in the present invention, impurities are added to the entire polycrystalline silicon including the part that will become the resistor, a thermal oxide film is formed on the part that will become the resistor, and the thickness of the oxide film is changed. By changing the degree of segregation of impurities in polycrystalline silicon, it is possible to manufacture resistors of the same size having two or more types of layer resistance values. This manufacturing method has the advantage that resistors with significantly different layer resistance values can be formed in the same size, greatly reducing the area required for resistors in semiconductor integrated circuit devices and improving the degree of integration. can be done.

[Brief explanation of the drawing]

1 to 6 are cross-sectional views for explaining embodiments of the present invention. Here, the symbols in the figure are 1...Substrate, 2...Field insulating film, 3...
Polycrystalline silicon film, 4... Wiring polycrystalline silicon,
5, 8, 9, 10...Resistor polycrystalline silicon,
6, 12, 14... thermal oxide film, 7, 11, 13...
...It is an oxidation-resistant material.

Claims (1)

[Claims] 1 A step of forming a plurality of polycrystalline silicon patterns containing impurities at a constant concentration on a semiconductor substrate via an insulating film, and oxidizing the surface of the polycrystalline silicon by different thicknesses to create different layer resistance values. A method for manufacturing a semiconductor integrated circuit device, comprising the step of forming two or more types of resistors.