JPH05335488A - Metallic thin film resistor - Google Patents

Abstract

PURPOSE:To lessen the temperature coefficient of a metallic thin film resistor and to make it possible to obtain a stable resistance value for the resistor by a method wherein a reduction in an irregularity in the form of an insulating layer to contact to the metallic thin film resistor due to a shift of a process processing is made possible and at the same time, the effect of a stress from the insulating later to contact to the resistor is lessened. CONSTITUTION:A wiring layer 13 is contacted to a metallic thin film resistor 12, which is deposited on an insulative base 11 and is patterned into a prescribed form. The layer 13 is formed in such a way that the film thickness (g) of a contact part 16 of the layer 13 to the resistor 12 is thinner than the film thickness (h) of a wiring layer main body part 13. Thereby, it becomes possible to lessen an irregularity (w) in the form of the contact part 14 of the layer 13 to the resistor 12 due to a shift of a process processing.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a metal thin film resistor, and more particularly to the shape of a wiring layer in contact with the metal thin film resistor.

Metal thin film resistors have a small temperature coefficient,
It is used in electronic exchange subscriber circuits and communication circuits because it can stably maintain the resistance value with high accuracy until the life of the semiconductor integrated circuit device.

Further, in recent years, higher reliability and higher precision of the semiconductor integrated circuit device have been required more than ever before, and the metal thin film resistor having the above-mentioned advantages is about to be used for a general-purpose semiconductor integrated circuit device.

[0004]

2. Description of the Related Art A conventional method of manufacturing a metal thin film resistor will be described in order of steps with reference to FIGS.

[Step 1, FIG. 12] A metal thin film is deposited on an insulating base 41 and then patterned into a predetermined shape to form a metal thin film resistor 42.

[Step 2, FIG. 13] A wiring layer 43 is deposited on the entire surface. [Step 3, FIG. 14] Wiring layer 4 on metal thin film resistor 42 other than contact portions 44a and 44b with metal thin film resistor 42
3 is removed by wet etching.

[0007]

The conventional metal thin film resistor has the following problems. (1) The resistance value of the metal thin film resistor 42 is
Portions 44a, 44 between the wiring layer 43a and the wiring layers 43b
It is determined by the effective length between b.

However, in step 3 (FIG. 14), contact portions 44a and 44b with the metal thin film resistor 42 are formed.
When removing the wiring layer 43 on the metal thin film resistor 42 other than the above, wet etching is used to secure a selection ratio and to prevent the metal thin film resistor 42 from being damaged. As a result, since the etching of the wiring layer 43 progresses isotropically, variations in the etching cause variations in the effective length of the metal thin film resistor 42, and the resistance value of the metal thin film resistor 42 fluctuates. ..

(2) The contact portions 44a and 44b between the wiring layer and the metal thin film resistor 42 are formed by the wiring layer bodies 43a and 43b.
It has the same film thickness as, and is quite thick. Therefore, the metal thin film resistor 42 is easily affected by the stress from the wiring layers 43a and 43b via the contact portions 44a and 44b. As a result, the temperature coefficient of the resistance value of the metal thin film resistor 42 becomes large.

The present invention solves the above problems and makes it possible to reduce variations due to process processing shifts, and also to reduce the temperature coefficient by reducing the influence of stress from the wiring layer in contact. It is an object of the present invention to provide a metal thin film resistor, particularly a shape of a wiring layer in contact with the metal thin film resistor, which is small in size and has a stable resistance.

[0011]

In order to achieve the above object, the metal thin film resistor according to the present invention has a wiring layer contacting a metal thin film deposited on an insulating substrate and patterned into a predetermined shape. The film thickness of the wiring layer at the contact portion with the metal thin film resistor is thinner than that of the wiring layer main body.

[0012]

1 is a diagram showing a metal thin film resistor according to the present invention. In the figure, 11 is a base, 12 is a metal thin film resistor, 13 is a wiring layer, and 14 is a contact portion.

FIG. 2 is a diagram showing a conventional metal thin film resistor. In the figure, 11 'is a base, 12' is a metal thin film resistor, 1
3'is a wiring layer, and 14 'is a contact portion.

The operation of the metal thin film resistor according to the present invention shown in FIG. 1 will be described below in comparison with the conventional metal thin film resistor shown in FIG. As shown in FIG. 1, in the metal thin film resistor according to the present invention, the film thickness of the wiring layer 13 is h, the film thickness of the contact portion 14 is g, and the variation in the width of the contact portion 14 due to the process processing shift is w.

Further, as shown in FIG. 2, in the conventional metal thin film resistor, the film thickness of the wiring layer 13 'is h', the film thickness of the contact portion 14 'is g', and the contact portion 14 'due to the process processing shift. The width variation is w '.

As can be seen from FIGS. 1 and 2, the conventional metal thin film resistor has g '= h', whereas the metal thin film resistor according to the present invention has g <h. Therefore, w <
w '. That is, in the metal thin film resistor according to the present invention, the variation w in the width of the contact portion 14 due to the process processing shift can be made smaller than that in the conventional metal thin film resistor.

As a result, the variation in the effective length of the metal thin film resistor 12 due to the process processing shift can be suppressed to a small value, so that the variation in the resistance value can be suppressed. Further, in the metal thin film resistor according to the present invention, the contact portion 14
Since the film thickness g of the metal thin film is smaller than the film thickness h of the wiring layer 13, the influence of the stress applied to the metal thin film resistor 12 from the wiring layer 13 can be reduced, and the temperature coefficient of the resistance value can be reduced. It will be possible.

[0018]

(Embodiment 1) A first method of manufacturing a metal thin film resistor according to the present invention will be described in order of steps with reference to FIGS.

[Step 1, FIG. 3] A metal thin film forming a metal thin film resistor is deposited on the insulating base 21 to a thickness of about 500 Å by a sputtering method. As the metal thin film forming the metal thin film resistor, for example, CrSi, CrSiO, or the like is used.

The metal thin film constituting the metal thin film resistor is patterned into a predetermined shape by the photolithography technique and the etching technique to form the metal thin film resistor 22. [Step 2, FIG. 4] Al is sputtered on the entire surface to about 5 Al.
The wiring layer (1) 23 is formed by depositing it to a thickness of 00Å.

[Step 3, FIG. 4, FIG. 5] Metal thin film resistor 22
The wiring layer (1) 23 on the metal thin film resistor 22 is removed by etching, leaving a portion contacting with. Wet etching is used for this etching in order to secure the selection ratio and to prevent the metal thin film resistor 22 from being damaged.

CVD (Chemical Vapor Deposi
insulation film 24 is deposited to a thickness of about 0.5 μm. As the insulating film 24, for example, PSG (PhosphoSi
licate Glass) is used.

[Step 4, FIG. 5 and FIG. 6] The insulating film 24 is patterned into a shape including a contact portion with the metal thin film resistor 22 by photolithography and etching.

[Step 5, FIG. 7] Al is deposited to a thickness of about 1 μm on the entire surface by a sputtering method to form a wiring layer (2) 25.

[Step 6, FIG. 7, FIG. 8] Metal thin film resistor 22
The portion of the wiring layer (2) 25 containing the is removed by etching. Since it is not necessary to consider damage to the metal thin film resistor 22 in this etching, either wet etching or dry etching may be used.

The metal thin film resistor according to the present invention is completed through the above steps. As shown in FIG.
2 and the contact portion 26 between the wiring layer (1) 23a and 23b
The film thickness g of a and 26b is smaller than the film thickness h of the wiring layer main body including the wiring layers (1) 23a and 23b and the wiring layers (2) 25a and 25b. As a result, the variation in the effective length of the metal thin film resistor 22 due to the process processing shift can be suppressed to be small, and the variation in the resistance value can be suppressed. Moreover, since the influence of the stress applied to the metal thin film resistor 22 from the wiring layer body can be reduced, the temperature coefficient of the resistance value can be reduced.

Further, since the metal thin film resistor 22 is covered with the insulating film 24, the stress from the interlayer insulating film and the cover film can be relaxed. (Embodiment 2) A second method for manufacturing a metal thin film resistor according to the present invention will be described in order of steps with reference to FIGS.

[Step 1, FIG. 9] A metal thin film constituting a metal thin film resistor is deposited on the insulating base 31 to a film thickness of about 500 Å by a sputtering method. As the metal thin film forming the metal thin film resistor, for example, CrSi, CrSiO, or the like is used.

The metal thin film constituting the metal thin film resistor is patterned into a predetermined shape by the photolithography technique and the etching technique to form the metal thin film resistor 32. Al is deposited to a thickness of about 1 μm on the entire surface by sputtering to form the wiring layer 33.

[Step 2, FIG. 9, FIG. 10] Metal thin film resistor 3
The portion of the wiring layer 33-1 containing 2 is selectively etched to be thinned to about 0.5 μm. Either wet etching or dry etching may be used for this etching.

[Step 3, FIG. 10 and FIG. 11] The metal thin film resistor 32 is left, except for the portion in contact with the metal thin film resistor 32.
The upper wiring layer 33-2 is etched and removed. Wet etching is used for this etching in order to secure the selection ratio and to prevent the metal thin film resistor 32 from being damaged.

The metal thin film resistor according to the present invention is completed through the above steps. As shown in FIG. 11, contact portions 34a between the metal thin film resistor 32 and the wiring layers 33a and 33b,
The film thickness g of 34b is smaller than the film thickness h of the wiring layer body including the wiring layers 33a and 33b. As a result, the variation in the effective length of the metal thin film resistor 32 due to the process processing shift can be suppressed to be small, and the variation in the resistance value can be suppressed. Further, since the influence of the stress applied to the metal thin film resistor 32 from the wiring layer bodies 33a and 33b can be reduced, the temperature coefficient of the resistance value can be reduced.

[0033]

According to the present invention, in the metal thin film resistor, the film thickness of the contact portion between the metal thin film resistor and the wiring layer is
Since the thickness of the wiring layer is thinner than that of the main body of the wiring layer, the variation in the effective length of the metal thin film resistance due to the process processing shift can be suppressed to be small, so that the variation in the resistance value can be suppressed.

Further, since the film thickness of the contact portion between the metal thin film resistor and the wiring layer is thinner than the film thickness of the wiring layer body, the influence of the stress exerted on the metal thin film resistor by the wiring layer body should be small. Therefore, the temperature coefficient of resistance can be reduced.

Further, by covering the metal thin-film resistance with the insulating film, it becomes possible to relieve the stress from the interlayer insulating film and the cover film, so that the temperature coefficient of the resistance value can be made smaller.

[Brief description of drawings]

FIG. 1 is a diagram showing a metal thin film resistor according to the present invention.

FIG. 2 is a diagram showing a conventional metal thin film resistor.

FIG. 3 is a diagram showing a process 1 of Example 1.

FIG. 4 is a diagram showing a process 2 of Example 1.

FIG. 5 is a diagram showing a process 3 of Example 1.

FIG. 6 is a diagram showing a process 4 of Example 1.

FIG. 7 is a diagram showing a process 5 of Example 1.

FIG. 8 is a diagram showing a process 6 of Example 1.

FIG. 9 is a diagram showing a process 1 of Example 2.

FIG. 10 is a diagram showing a process 2 of Example 2.

FIG. 11 is a diagram showing a process 3 of Example 2.

FIG. 12 is a diagram showing a process 1 of a conventional example.

FIG. 13 is a diagram showing step 2 of the conventional example.

FIG. 14 is a diagram showing step 3 of the conventional example.

[Explanation of symbols]

 11 Underlayer 12 Metal thin film resistor 13 Wiring layer 14 Contact part

Claims (1)

[Claims] 1. A metal thin-film resistor in which a wiring layer is contacted with a metal thin film deposited on an insulative ground and patterned into a predetermined shape, and the film thickness of the wiring layer at a contact portion with the metal thin-film resistor. However, the metal thin film resistor is characterized by being thinner than the film thickness of the wiring layer body.