JPH047561B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a metal thin film resistor using an alloy thin film made of three components: tantalum (Ta), chromium (Cr), and silicon (Si). In recent years, there has been remarkable progress in thin film resistors, and tantalum nitride thin film resistors have been developed as highly stable resistors, and Cr-SiO cermets have been put into practical use as resistors with high specific resistance.
Additionally, tantalum nitride thin film resistors have a good temperature coefficient of resistance and excellent stability. The active sputtering method is usually used to produce tantalum nitride thin films, which requires the introduction of a small amount of active gas into a vacuum chamber and strict control of its control. Also, Cr−SiO
Cermet resistors have many manufacturing technology problems, such as low stability and poor reproducibility. By the way, silicon, which was invented earlier, tantalum, niobium, titanium, zircon, molybdenum,
A two-component thin film resistor containing one of tungsten or the like compensates for the above-mentioned deficiencies and can be highly evaluated as the most excellent thin film resistor at present.
That is, by adjusting the heat treatment temperature, it is possible to have a low temperature coefficient of resistance over a wide range of resistivity. However, the stability of a resistor is related to the heat treatment temperature, and if you want high stability, the heat treatment temperature will also be high, and the composition or specific resistance that corresponds to the low temperature coefficient of resistance at that time is determined by yourself, and there is no freedom of choice. It disappears. In other words, if a two-component alloy thin film resistor is subjected to the most stable heat treatment and a small temperature coefficient of resistance is obtained, the specific resistance and composition will be determined by themselves. The problem is that it is subject to significant restrictions. Regarding the binary metal thin film of tantalum and chromium, as shown in Figure 1, the temperature coefficient of resistance changes rapidly from positive to negative around the tantalum composition ratio of 15 to 20%. is 0ppm/
A drawback is that it is difficult to manufacture metal thin film resistors at temperatures close to ℃ with good reproducibility. The present invention has been developed in view of the above-mentioned conventional difficulties.The present invention is constructed using an alloy thin film consisting of tantalum, chromium, and silicon, and is heat-treated appropriately to achieve a resistance temperature coefficient of 0 ppm/°C. The object of the present invention is to provide a highly stable metal thin film resistor that can be easily manufactured and has excellent moisture resistance load life characteristics and high temperature load life characteristics. In order to achieve such an object, according to the present invention, an alloy thin film consisting of three components of 40 at % or less tantalum, 95 at % or less chromium, and 80 at % or less silicon is used, and this alloy thin film is heated preferably at 400°C.
The heat-treated metal thin film resistor is constructed as described above. Preferred embodiments of the present invention will be described below with reference to the drawings. FIG. 2 shows the composition ratio and temperature coefficient of resistance of an untreated alloy thin film consisting of a ternary system of tantalum, chromium, and silicon. In Figure 2, a shows a curve with a resistance temperature coefficient of +100ppm/°C, and b shows a curve with a resistance temperature coefficient of +100ppm/°C.
The curve c shows the curve at -100 ppm/°C.
In other words, compared to Figure 1, the range of ±100ppm/℃ has become larger, and in particular, the range of possible composition ratios at 0ppm/℃ has become wider. This means that alloy thin films with a temperature coefficient of resistance of 0 ppm/°C can be manufactured with good reproducibility. Figure 3 shows the composition ratio and temperature coefficient of resistance when further heat treated at a temperature of 600℃, where a' is the +100ppm/℃ curve, b' is the 0ppm/℃ curve,
c′ shows the curve at −100 ppm/°C. Comparing Figure 3 and Figure 2, the temperature coefficient of resistance is ±100ppm/
Although the range of °C does not change much, in Figure 3
It is noticeable that the range of composition ratios that can be taken at 0ppm/℃ has become wider, making it easier to determine the temperature coefficient of resistance.
This means that it is possible to produce alloy thin films with a temperature of 0 ppm/°C. Examples of these are shown in Table 1. As can be seen from Table 1, the temperature coefficient of resistance can be varied depending on the heat treatment temperature.

【table】

[Table] Here, the method for preparing the sample of the present invention will be explained. The DC sputtering conditions were as follows: After evacuating the inside of the bell gear to 3 x 10 ^-7 Torr, high-purity argon gas was introduced at 18 to 20 x 10 ^-3 Torr, cathode voltage was -5.7 to -6.5 KV, and current density was 0.08 mA. / ^cm2 by bipolar sputtering. Film formation speed is 50~
150〓/min. The film composition was determined by using tantalum, chromium, and silicon metals and changing their area ratios. Further, the heat treatment was carried out in the air at a predetermined temperature for 3 minutes. On the other hand, almost the same effect could be obtained by heating the resistive substrate at a predetermined temperature for several minutes even in a vacuum, or by heating the resistive substrate during sputtering. Next, in order to show the stability of the above alloy thin film as a resistor, FIGS. 4 and 5 show the results of a humidity load life test and a high temperature load life test. The sample at this time was hetantal, a base of cylindrical forsterite.
A thin alloy film containing 16.7 at.% chromium, 53 at.% chromium, and 30.3 at.% silicon was deposited and spirally cut to form a resistor with a resistance value of 3 kΩ. Figure 4 is a graph of the results of a humidity-resistant load life test, in which the rated voltage was applied for 1000 hours in a cycle of 1.5 hours of load and 0.5 hours of no load in an atmosphere with an ambient temperature of 40±2℃ and a relative humidity of 90 to 95%. It shows the rate of change in resistance value when In the graph, d is the untreated characteristic, e, f, and g are each 400
These are the characteristics when heat treated at temperatures of ℃, 500℃, and 600℃. As is clear from the graph, even in the untreated case it is as low as 0.7% or less, and as the heat treatment temperature increases, especially in heat treatment at 600℃, it decreases by 0.03%.
The following excellent results can be obtained. FIG. 5 is a graph of the high temperature load life test results. Rated voltage in an atmosphere with an ambient temperature of 70±2℃
In a 1.5 hour load, 0.5 hour no load cycle
It shows the rate of change in resistance value when repeated for 1000 hours, and d′ in the graph is the untreated characteristic;
e′, f′, and g′ are the characteristics when heat treated at temperatures of 400°C, 500°C, and 600°C, respectively. As is clear from the graph, even untreated products are less than 0.7%.
Excellent results can be obtained with all heat-treated products having a content of 0.03% or less. As described above, in terms of humidity resistance load life characteristics and high temperature load life characteristics, stability is excellent even when untreated, and in particular, the stability increases as heat treatment is performed at a higher temperature, making it extremely excellent. As is clear from the above embodiments, according to the present invention, the temperature coefficient of resistance is 0 ppm/°C by using a thin alloy film consisting of tantalum, chromium, and silicon, and applying appropriate heat treatment. The resistor can be easily manufactured with good reproducibility, and has excellent humidity resistance load life characteristics and high temperature load life characteristics, and can have high stability.

[Brief explanation of drawings]

Figure 1 is a graph showing the composition ratio and temperature coefficient of resistance of a binary metal thin film, and Figure 2 is a graph showing the temperature coefficient of resistance of a metal thin film resistor made of three components, tantalum, chromium, and silicon, at its composition ratio when untreated. FIG. 3 is a ternary alloy diagram showing the heat treatment at 600°C in FIG. 2. FIG. FIG. 5 is a graph showing the results of a high temperature load life test of the metal thin film resistor of the present invention.

Claims (1)

[Scope of Claims] 1. A metal thin film resistor, characterized in that it is constructed using an alloy thin film consisting of three components: tantalum at 40 atomic % or less, chromium at 95 atomic % or less, and silicon at 80 atomic % or less. 2. The metal thin film resistor according to claim 1, characterized in that the alloy thin film is heat-treated at a temperature of 400° C. or higher.