JPS58182201A - Resistor - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a resistor, particularly a resistor using a polycrystalline silicon film, and provides a resistor suitable for use in AD and DA converters that require high precision. be.

The weight resistance and ladder resistance used in AD and DA conversion devices are 1. High precision is required depending on the number of bits to be converted. Therefore, conventionally, a falling resistor using Ni-0r or the like as a resistive material has been used.

However, Ni and Cr are
Due to the formation of deep impurity levels for i, compatibility of the manufacturing process was difficult.

- Doping polycrystalline silicon with impurities and using it as wiring or resistors is a method of doping polycrystalline silicon with impurities.
) M (JS, etc. had already used it. However.

These original uses are digital circuits (mainly memory) with 8
9. It did not require much precision as a resistor.

The present invention provides a polycrystalline silicon high precision resistor for analog circuits.

It is known that when an impurity such as E3oron is ion-implanted into polycrystalline silicon, the temperature coefficient of the resistor changes from negative to positive with respect to the dose. It is also known that, as a matter of course, the resistivity decreases with respect to dosing. All of these changes are rapid;
Controllability was poor.

The cause is said to be due to multiple MJts and defects in silicon. As a way to revise this, H
Annealing in a wax atmosphere or a plasma hydrogen atmosphere is effective. Results from laser annealing are expected. In fact, as shown in FIG. 1, the change in resistivity with respect to dose approaches the change in resistivity of single crystal silicon by laser annealing. Furthermore, as shown in Figure 2, an example of an impurity is boron (B
) changes in the temperature coefficient with respect to the dose amount are moderated. From these experiments, it is possible to determine the polycrystalline silicon film thickness and dose that give a zero temperature coefficient and perform laser annealing.
A method for obtaining high precision resistors.

The laser annealing conditions cannot be uniquely determined because they depend on the thickness of the polycrystalline silicon film. As an example based on the present invention, the polycrystalline silicon film thickness is 2470 mm, the dose is j,
5 X 10 atom/c, in the case of A, using an Alcon laser in CW mode at 13 W, laser spot diameter 25 μm, scan speed 12.5 Cr1V8 eo
.

\ Good results were obtained when the laser beam overlap was 60% and the substrate temperature was 350'1:.

After laser annealing, the polycrystalline silicon is melted by the laser beam spot diameter and T wrap rate.
Since the beams are recrystallized, crystal defects exist at the boundaries between the beams. Therefore, when polycrystalline silicon is laser annealed and then the butter 7 is extracted using dry etching technology or the like to form an electrode, if the electric field is perpendicular to the crystal defect, that is, the direction scanned by the laser beam, it will have a stable value as a resistor. I can't wait. especially.

Stability is not maintained when the resistance value changes over time for about 100 hours.

Therefore, if the electrodes are formed in a pattern so that an electric field is applied in parallel to the scanning direction of the laser beam, stability of the resistance value can be obtained during the change over time. The cause of this is, as mentioned above, in the polycrystalline silicon in which the laser beam interacts with N.

This is probably due to the presence of crystal defects.

FIG. 3 shows an embodiment of a resistor according to the present invention.

In FIG. 4, %1 indicates a laser annealed polycrystalline silicon film. 2 shows electrode wiring made of AI or the like. 3 shows traces caused by laser annealing. That is, the laser beam scans (
scanned). If the width of the polycrystalline silicon film 1 is larger than the laser beam diameter, traces will be created due to beam overlap when scanning is repeated. This is as described above. Reference numeral 4 indicates the scanning direction of the laser beam, and indicates the direction of the electric field generated by the voltage applied to the electrode 2, that is, the direction in which current flows. Reference numeral 6 indicates an insulating film, and 6 indicates the semiconductor substrate.

Polycrystalline silicon film 1 is formed by the CVP method or the like.

The film thickness is determined based on sheet resistance and conditions for providing a zero temperature coefficient. In this embodiment, there are approximately 2,500 people. In this case, impurity ion implantation is also determined by the designer's intentions.

Dopant H+, dose i 1.5 x 1015
atarrv/c7.

The implantation energy is 60 keys. After ion implantation, annealing is performed at about 1000'C. This heat treatment was thought to be unnecessary since laser annealing was performed later, but from the standpoint of stability, the results were slightly better if heat treatment was performed. After the heat treatment, any method that is advantageous in terms of the work process may be used, such as performing laser annealing immediately or patterning the polycrystalline silicon film and then performing laser annealing. Laser annealing is approximately 26μm, cw momo” and approximately 13W.
, scanning speed 12.6 (m/aeo), beam oats (-lap 60%, substrate temperature 360°C. of polycrystalline silicon film) (turning and laser scanning direction are applied to the polycrystalline silicon film 1 The beam should be parallel to the direction of the electric field.It goes without saying that other energy beams may be used in place of the laser.

FIG. 4 is a graph showing whether a polycrystalline silicon film can be subjected to laser annealing and changes over time depending on whether the laser beam scanning direction is perpendicular to the electric field or parallel to it. Fourth
In the figure, (A) is % without laser annealing (B)
C1 is the measured change over time when laser annealing is used and the electric field is perpendicular to the scanning direction, and C1 is when laser annealing is used and the electric field is parallel to the scanning direction.

It is clear from the above explanation that the beam scanning direction in which the polycrystalline silicon film is annealed with an energy beam,
By patterning this polycrystalline silicon film and forming electrodes, the pattern and electrodes are formed so that the direction of the electric field matches the direction of the electric field, thereby providing stability including changes over time of the resistor.

Therefore, the present invention greatly contributes to the manufacture of high-precision resistors, since the high-precision resistors required for AD and DA converters can be formed from polycrystalline silicon, making the manufacturing process compatible. .

[Brief explanation of the drawing]

FIG. 1 shows the change in resistivity with respect to dose. 2 is a diagram showing changes in temperature coefficient with respect to dose, FIG. 3(a) is a plan view of a polycrystalline silicon resistor according to an embodiment of the present invention, and FIG. a) I −
FIG. 4, a sectional view taken along line I', is a diagram showing the temporal change characteristics of the polycrystalline silicon resistor. 1... Polycrystalline silicon film, 2... Old electrode wiring, 4... --- Scan direction. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure 2B

Claims (1)

[Claims] A resistance region formed by annealing polycrystalline silicon doped with impurities using an energy beam. A resistor comprising: an electrode formed in the resistance region so that an electric field is applied in parallel to a fixed feeding direction of the energy beam.