Thin film resistor

Abstract

A thin film resistor has a higher resistivity compared to that of a conventional thin film resistor. The thin film resistor includes 30-45 at % of nickel, 15-30 at % of chromium, 1-10 at % of manganese, 10-30 at % of yttrium and 1-20 at % of tantalum.

Claims

1. A thin film resistor comprising 30-45 at % of nickel, 15-30 at % of chromium, 1-10 at % of manganese, 10-30 at % of yttrium and 1-20 at % of tantalum.

2. The thin film resistor as claimed in claim 1, wherein the thin film resistor comprises 42.9-43.8 at % of nickel, 19.9-20.7 at % of chromium, 4.7-5.6 at % of manganese, 24.8-25.6 at % of yttrium and 4.3-7.7 at % of tantalum.

3. The thin film resistor as claimed in claim 1, wherein sum of atomic percentages of Ni and Ta is larger than 45 at %.

4. The thin film resistor as claimed in claim 1, wherein sum of atomic percentages of Y and Ta is larger than 30 at %.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The present invention will become more fully understood from the detailed description given hereinafter and the accompanying drawings which are given by way of illustration only, and thus are not limitative of the present invention, and wherein:

(2) FIG. 1 depicts a line chart illustrating the relationship between the resistivity and tantalum (Ta) content of the thin film resistors of groups A0-A4.

(3) FIG. 2 depicts a line chart illustrating the relationship between the temperature coefficient of resistance (TCR) and tantalum (Ta) content of the thin film resistors of groups A0-A4.

(4) In the various figures of the drawings, the same numerals designate the same or similar parts. Furthermore, when the term first, second and similar terms are used hereinafter, it should be understood that these terms refer only to the structure shown in the drawings as it would appear to a person viewing the drawings, and are utilized only to facilitate describing the invention.

DETAILED DESCRIPTION OF THE INVENTION

(5) A thin film resistor according to an embodiment of the present invention can include nickel (Ni), chromium (Cr), manganese (Mn), yttrium (Y) and tantalum (Ta). As an example, the thin film resistor can include 30-45 at % of Ni, 15-30 at % of Cr, 1-10 at % of Mn, 10-30 at % of Y and 1-20 at % of Ta. Preferably, the thin film resistor includes 42.9-43.8 at % of Ni, 19.9-20.7 at % of Cr, 4.7-5.6 at % of Mn, 24.8-25.6 at % of Y and 4.3-7.7 at % of Ta. Moreover, the sum of atomic percentages of Ni and Ta is larger than 45 at %. Alternatively, the sum of atomic percentages of Y and Ta is larger than 30 at %. With such performance, the thin film resistor has not only the increased resistivity, but also the temperature coefficient of resistance (TCR) near zero.

(6) The thin film resistor can be produced by any conventional method for producing thin film resistors, such as vacuum evaporation or sputtering. In this embodiment, D.C. magnetron sputtering is used, metal meeting the composition of the thin film resistor is used as the target, and sputtering is conducted in a vacuum by using a D.C. current with a fixed power which can be set at 70 W. After sputtering, annealing is conducted for 4 hours at 300 C. Thus, a thin film resistor of a thickness smaller than 300 nm is deposited on a substrate. The thickness of the thin film can be adjusted according to the time and power of sputtering, which can be appreciated by a person having ordinary skill in the art, and therefore is not limited in the present invention.

(7) Accordingly, due to the ingredients (Ni, Cr, Mn, Y and Ta) and the specific ratio (30-45 at % of Ni, 15-30 at % of Cr, 1-10 at % of Mn, 10-30 at % of Y and 1-20 at % of Ta), the thin film resistor can have not only a low TCR in the range of +25 ppm/ C. to 25 ppm/ C., but also a significant higher resistivity compared to the conventional thin film resistor.

(8) To evaluate the thin film resistor according to the present invention has the low TCR and the high resistivity, the resistivity and the TCR at 25 C. of the thin film resistors of groups A1-A4 shown in TABLE are measured. The thin film resistor without tantalum (Ta), the conventional thin film resistor, is used as the thin film resistor of group A0.

(9) TABLE-US-00001 TABLE 1 Groups Ni (at %) Cr (at %) Mn (at %) Y (at %) Ta (at %) A0 44.9 21.8 6.6 26.7 0 A1 42.9 19.9 4.7 24.8 7.7 A2 43.3 20.2 5.1 25.1 6.3 A3 43.4 20.3 5.2 25.2 5.9 A4 43.8 20.7 5.6 25.6 4.3

(10) Referring to FIG. 1, the thin film resistors of groups A0-A4 have the resistivity of 1580, 2966, 2589, 2433 and 2117 -cm, respectively. That is, the thin film resistors of groups A1-A4 have the resistivity higher than the thin film resistor of group A0, indicating the thin film resistor according to the present invention has the resistivity higher than the conventional thin film resistor. Moreover, the atomic percentage of Ta increases (from 4.3 at % to 7.7 at %), the resistivity of the thin film resistor increases.

(11) In addition, referring to FIG. 2, the thin film resistors of groups A0-A4 have the TCR of 33.77, 9.65, 13.66, 15.08 and 18.75 ppm/ C., respectively. That is, the thin film resistors of groups A1-A4 have the TCR in the range of +25 ppm/ C. to 25 ppm/ C., indicating under the condition of the low TCR, the thin film resistor according to the present invention has the significant higher resistivity compared to the conventional thin film resistor.

(12) Accordingly, due to the ingredients (Ni, Cr, Mn, Y and Ta) and the specific ratio (30-45 at % of Ni, 15-30 at % of Cr, 1-10 at % of Mn, 10-30 at % of Y and 1-20 at % of Ta), the thin film resistor can have not only a low TCR in the range of +25 ppm/ C. to 25 ppm/ C., but also a significant higher resistivity compared to the conventional thin film resistor.

(13) Although the invention has been described in detail with reference to its presently preferable embodiment, it will be understood by one of ordinary skill in the art that various modifications can be made without departing from the spirit and the scope of the invention, as set forth in the appended claims.