JPH01286355A - Thin film resistance element - 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 [Field of Industrial Application] The present invention relates to the shape of a thin film resistive element formed on an insulating film.

[Conventional technology]

Conventionally, thin-film resistive elements are formed on a flat insulating film, and a pattern that achieves a predetermined resistance value is formed by determining the length-to-width ratio of the flat pattern based on the sheet resistance determined by the thickness and material of the resistive thin film. Was.

[Problem to be solved by the invention]

In the conventional thin film resistance element described above, in order to achieve high resistance, it is necessary to increase the length-to-width ratio of the resistance pattern. One possible method for increasing the length-to-width ratio of a resistor pattern is to make the pattern width thinner, but there is a limit in terms of current capacity and pattern accuracy. Therefore, a desired high resistance value is usually achieved by increasing the pattern length. However, increasing the pattern length requires a correspondingly larger area, which is very disadvantageous in terms of density in semiconductor integrated circuit devices and the like.

An object of the present invention is to eliminate the above-mentioned drawbacks and provide a thin film resistive element that does not require a large area and can provide a high resistance value.

[Means for resolving division stirrups]

In the thin film resistance element of the present invention, the underlying insulating film has an uneven portion on the path, and the diameter and thickness of the recess are set so that the thin films formed on the opposing sides of the recess do not come into contact with each other. be.

, [Function] The effective length of the thin film resistance element is increased by providing the uneven portion. Moreover, on the projection plane, the area can be the same as when the insulating film is flat.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1(a) is a plan pattern diagram of the first embodiment,
Figure (b) is a sectional view taken along the line AA'.

The thin film resistance element is formed as a linear polysilicon resistance pattern 1 on a silicon nitride film 4 laminated on a silicon substrate 3. The silicon nitride film 4 is provided with four parts 2 perpendicular to the route on the path, and as shown in FIG. A current path is also formed within 2. Therefore, even if the projection plane of the thin film resistive element onto the silicon substrate 3 has the same length as that of a thin film resistive element formed on a flat insulating film, the effective path length becomes longer. This allows a high resistance value to be obtained without significantly narrowing the width.

In this embodiment, for example, after forming a silicon nitride film 4 with a thickness of 3 gm on the entire surface of the silicon substrate 3 by CVD method,
This can be realized by forming a groove with a depth of 271 m in the silicon nitride film 4 using a reactive ion etching method and patterning a polysilicon film 5 with a thickness of 0.5 pm containing phosphorus as an impurity. In this case, the length of the polysilicon film 5 on the projection plane is assumed to be 14 JLm as shown in FIG.
By providing the four parts 2 of the silicon nitride film 4 at three locations as shown in a) and (b), the effective length of the polysilicon resistor pattern 1 becomes 23 m, which is approximately 1 m long of the resistor pattern formed on the flat insulating film. .6 times as long. Therefore, the same
A resistance 1.6 times larger than that of conventional technology can be achieved in terms of area. Assuming that the width of the polysilicon film 5 is 2 gm and the sheet resistance is 40 Ω/hole, the resistance can be increased from 280 Ω in the prior art to 460 Ω. The resistance value can be increased as the number of four parts 2 of the silicon nitride film 4 is increased.

Note that if the polysilicon films formed on the side surfaces of the four parts come into contact with each other, the effective length will not increase in this part. Therefore, it goes without saying that the film thickness and the diameter of the recess should be determined so that the above-mentioned contact does not occur.

Next, a second embodiment will be explained. FIG. 2(a) is a plane pattern diagram, and FIG. 2(b) is a sectional view taken along the line BB'.

In this embodiment, the silicon oxide film convex portion 7 is formed perpendicularly to the silicon chrome resistor pattern 6.

The portion sandwiched between the silicon oxide film convex portions 7 and the electrode end portion form a recess. To manufacture such a shape, for example, as shown in FIG. 2(b), after forming a silicon oxide film 9 with a thickness of 2JLm on a silicon substrate 8 by thermal oxidation, a silicon oxide film 9 with a thickness of 27Lm is formed.
pm polysilicon 10 is patterned using a reactive ion etching method and thermally oxidized to a thickness of 0.50 nm. This can be achieved by forming a silicon oxide film 11 of IILm and then patterning a silicon chrome film 12 with a thickness of 0.3 gm.

In the case of this embodiment as well, the length of the silicon chrome resistor pattern 6 on the projection plane is set to 141 as in the first embodiment.
Assuming Lm, the effective length is 257 h by forming the silicon oxide film convex portions 7 at three locations as shown in FIG. 2(b).
m, which is about 1.8 times the length of the resistance pattern formed on the flat insulating film. Therefore, a resistance 1.8 times that of the conventional technology can be achieved with the same area.

In the first and second embodiments, examples on silicon substrates have been described, but the invention is not limited to this, and it can also be realized on gallium arsenide substrates and various insulating substrates, and thin film resistors and insulating films can also be used. The materials of the plugs are applicable within the scope of the invention.

〔Effect of the invention〕

As explained above, in the present invention, F! The effective length of the path is increased by providing an uneven portion in the base insulating film of the film resistance element so that the path of the resistance pattern is formed also within the recess. As a result, high resistance can be achieved with a small substrate area, which is highly effective in improving the degree of integration in semiconductor integrated circuits and the like.

[Brief explanation of the drawing]

FIG. 1 is a plan pattern diagram and a sectional view of a first embodiment of the present invention, and FIG. 2 is a plan pattern diagram and a sectional diagram of a second embodiment. l...Polysilicon resistance pattern, 2...(silicon nitride film) recess, 5...polysilicon film, 6...silicon chrome resistance pattern, 7...silicon oxide film protrusion, 10...・Polysilicon, 11...Silicon oxide film. Patent applicant: NEC Corporation Representative: Susumu Uchihara, patent attorney Figure 1 Figure 2

Claims (1)

[Claims] In a linear thin film resistance element formed on an insulating film, the underlying insulating film has an uneven portion on the path, and the diameter of the recess is adjusted so that the thin films formed on opposite sides of the recess do not come into contact with each other.
A thin film resistance element characterized by having a set film thickness.