JPS5935403A - Method of forming ni-cr thin film 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 Field of Industrial Application The present invention relates to a method for forming a Ni--Cr thin film resistor, and aims to provide a highly accurate and stable Ni--Cr thin film resistor.

Structure of the conventional example and its problems Generally commercially available Ni-Cr alloys are used for vapor deposition.
Many have a purity of around 19%. However, this purity refers to the purity of Ni and Cr in the base metal, not the purity of the Ni-Cr alloy.'Table 1 shows an example of the elemental analysis results of the 8ONi-20Cr alloy, which is the most common material for vapor deposition. .

Even if you form a thin film resistor using the stupidly purchased Nk-Cr alloy, you will not be able to obtain a pure Ni-Cr film resistor.
Furthermore, since the vapor pressure differs depending on the element (see Table 2), a stable Ni--Cr thin film resistor could not be obtained. Therefore, the features of the Ni-Cr11E film resistor (T, C, R are small, stable electrical characteristics are obtained, and in addition to the above, Co, Nb
, Mo, V, Si, etc.) were not fully exhibited.

OBJECTS OF THE INVENTION The present invention eliminates the above-mentioned conventional drawbacks, and aims to provide a highly accurate and stable Ni--Cr thin film resistor.

Structure of the Invention In order to achieve the above object, the method for forming a Ni-Cr thin film resistor of the present invention includes a method for forming a Ni-Cr thin film resistor on an insulating substrate.
After cleaning the gold surface, use an electron beam evaporator to scan the beam in vacuum to uniformly melt the Ni-Cr alloy, and if the volume of the Ni-Cr alloy is Nmt-, at least 500. ; (1~2)・N that consumed more than N times the amount
Depositing an i-Cr alloy on an insulating substrate as a deposition target,
This is to form a Ni-Cr resistance film.

DESCRIPTION OF EMBODIMENTS 1. A 14-bit structure as an embodiment of the method for forming a Ni--Cr thin film resistor according to the present invention. A method for forming a thin film ladder resistor for a converter will be explained based on the drawings. Ni-C
After ultrasonically cleaning r-alloy (manufactured by Dryper 691, heating wire type 1 product) with trichlorethylene, Ni-
Impurities and oxides on the surface were removed by dipping about 1 drop in a Cr etching solution (trade name: TFC, obtained from Boxipfun Co., Ltd.). Next, the electron beam evaporation equipment was installed, and the 10-”To
The entire Ni-Cr alloy was melted uniformly by scanning the electron beam so that it covered the entire Ni-Cr alloy in a vacuum of rr or higher (Consumption amount of Ni-Cr alloy after starting melting) (This was done until the value reached 150OA.) Through the above treatment, a 200A vapor deposition was performed using a classmate Ni-Cr alloy. On top of that, A/, was evaporated as an electrode, and At and Ni-C were deposited on the %Sl substrate.
The r thin film was patterned by photolithography. Finally, after forming a protective film, heat treatment was performed to stabilize the Ni--Cr thin film resistor. The Ni-Cr thin film resistor thus obtained has 14 pins) D/
The characteristics as a fuser resistor for a mucomparter were sufficiently satisfied.

Next, the reason for setting the conditions for forming the Ni-Cr thin film resistor will be described.

First of all, the reason why the N1-Cr alloy starts to be uniformly melted while scanning the electron beam and then consumes 1500λ is when the Ni-Cr alloy is uniformly melted and then evaporated at 200A each onto the Si substrate. , the film formation is Ni and Cr
This is the amount required to be consumed to fully satisfy the characteristics as a thin film ladder resistor for a D/A converter. It is.

Figure 1 shows the consumption of Ni-Cr alloy and the composition ratio of the film deposited on the substrate, and Figure 2 shows the extinction and D/
It shows the correlation with overlay error, which is one of the evaluation methods for an A converter. As can be seen from Figure 1, Ni
- When the consumption of Cr alloy is small, a large amount of Mn is deposited in addition to Ni and Cr, and it is not formed as a pure & Ni-Cr thin film resistor. It can be seen that a film is formed (Fe and Cu as impurities are not included in the figure because they are both less than α5wt%.) From Figure 2, it is one of the characteristics evaluation as a value converter. Ni-Cr which satisfies the accuracy ((LOO3%)) when the consumption of Ni-Cr alloy becomes 150OA or more
It can be seen that a thin film resistor can be obtained. However, these data are based on the case where the volume of the Ni-Cr alloy is ':A7ml/).The consumption amount of the Ni-Cr alloy varies depending on the volume of the Ni-Cr alloy. It was more than an example.

Second, although the 81 substrate is heated at 300° C. in the embodiment, it may be heated at 350° C. or lower.

It is shown in Figure 3 that the heating temperature of the Si substrate and 14 pins) D/
It shows the temperature coefficient of the upper 7 bits of the A/A converter i-Cr thin film ladder resistor.

For Si substrates deposited at 400°C, the variation between bit resistances is large, and if the heating temperature is 350°C or less, there is some difference in absolute value, but the variation between bit resistances is very small. . Another characteristic evaluation method is the overlay error of the D/A converter (14 pins), but this is hardly affected by the Si substrate heating temperature and is due to variations in the measurement error range, under any conditions. It fully satisfies 14-bit precision.

Thirdly, although the film was deposited on the Si substrate at a rate of 2 A/sec in the example, it may be at a rate of 5 A/sec or less. Figure 4 shows a Si substrate heated to 150°C and 350°C at room temperature, and then Ni-Cr deposited at film deposition rates of 2X/sec, 5^/sec, and 8^/sec, respectively. It shows the correlation with the overlay error of Ni-Cr thin film ladder resistors for D/A converters. It can be seen from FIG. 4 that if the Si substrate heating temperature is 350 DEG C. or less, the film deposition rate that satisfies the accuracy of the Ni--Cr thin film ladder resistor for a 14-bit D/A converter must be 5 AI seconds or less.

Finally, the ratio of Ni and Cr deposited on the insulating substrate is as follows: Ni-Cr alloy (8ONi, 20
Cr), but the composition of the film deposited on the Si substrate is Ni40wt%.
, the ratio of Cr is about 60wt%. However, as the number of evaporations increases, the amount of Cr in the Ni-Cr alloy decreases rapidly, and the film composition on the I/cSi substrate gradually increases the Ni ratio. As Nl increases, the temperature coefficient of the resistor also increases, and as is clear from Figure 5, S
When the Ni content in the film deposited on the i-substrate exceeds 60 wt%, the temperature coefficient of the Ni--Cr thin film resistor suddenly increases. On the contrary, a Ni--Cr thin film resistor in which the Cr content is 60 wt% or more exhibits a large negative temperature coefficient, as can be seen from FIG.

Therefore, in order to obtain a Ni-Cr thin film resistor with a small temperature coefficient, N3 should be 40-60 wt% and Cr should be 60-40 wt%.
% range is desirable. In addition, any Ni-
Even in Cr alloys, Ni-Cr is subjected to the consumption according to the present invention.
Ni is deposited on an insulating substrate using an alloy as a deposition target.
When forming a -Cr thin film resistor, a stable Ni-Cr thin film resistor can be obtained by ignoring the absolute value of the temperature coefficient. For example, 30wt% Ni, 70wt% Cr.
Even a Ni-Cr thin film resistor with a composition of 75wt% Ni can be obtained that fully satisfies the characteristics of a lapladder resistor for a D/A converter (14 pins);
(Even a Ni--Cr thin film resistor having a composition of 25 wt% r can be obtained that fully satisfies the characteristics as a ladder resistor for a 14-bit D/A converter.

Effects of the Invention As described above, according to the present invention, Ni-C, which is a material to be deposited,
R alloy is consumed by at least (500 Xa is the object to be deposited.

By controlling the film deposition rate, it became possible to form a Ni--Cr thin film resistor with high precision and stability.

[Brief explanation of drawings]

The drawings show examples of the present invention, and FIG. 1 is a graph showing the consumption amount of Ni-Cr alloy and the composition ratio of the film deposited on the substrate. Fig. 2 is a graph showing the correlation between Ni-Cr alloy consumption and overlay error, Fig. 3 is a graph showing the temperature coefficient of Ni-Cr thin film resistors deposited by varying the substrate heating temperature (ts), Figure 4 is a graph showing the correlation between Ni-Cr film deposition rate and kite alignment error, and Figure 5 is a graph showing the correlation between the film composition on the substrate and the temperature coefficient of the resistor. Agent: Mori Yoshihiro Moto Figure 1 Figure 2 ML-Cp Gold Sword) Precious Figure 3 t:v To resistance *NO Figure 4

Claims (1)

[Claims] In the step of forming L Ni -Cr @mimetic antibody on an insulating substrate, after cleaning the surface of the Ni-Cr alloy that is the object to be deposited, an electron beam evaporator is used to evaporate the Ni-Cr alloy in a vacuum. The Ni-Cr alloy is uniformly melted without scanning the N
If the volume of the i-Cr alloy is N, at least 500A (1 to 2). A method for forming a Ni-Cr thin film resistor forming a resistive film. 2 The composition of the Ni-Cr thin film resistor deposited on the insulating substrate is Ni (40-60 wt%) and Cr (60-40 wt%).
%) within the range of Ni-
Method for forming a Cr thin film resistor. When forming aNi-Cr thin film resistor on an insulating substrate,
A method for forming a Ni--Cr thin film resistor according to claim 1, wherein the temperature of the substrate is maintained below 350[deg.]C. 4. The method of forming a Ni-Cr thin film resistor according to claim 1, wherein the Ni-Cr vapor deposition rate is 5 A/sec or less.