JPS6122444B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for manufacturing a resistor made by thinning a carbide resistive material by sputtering. It is well known that this type of sputtering has been used as a method for manufacturing electronic components such as resistors and capacitors by forming thin films of various materials such as conductive materials, dielectric materials, and semiconductor materials. The most basic characteristics are determined by the resistor material (substance), and various materials are selected as the target material depending on the purpose. The process of forming a resistor also plays an important role in determining characteristics such as film quality, resistance value, amount of adhesion, and specific resistance. In sputtering, sputtering gas pressure, substrate temperature, high frequency power,
Sputtering time and gas atmosphere are the most important among the various parameters during sputtering. Sputtering is a development in which ionized gas molecules are accelerated by an electric field and collide with a target electrode to release target molecules, and the gas atmosphere used is usually argon gas at 10 ^-2 to ^{10 -3} Torr. The substrate temperature is usually maintained at an appropriate temperature in order to obtain good adhesion. The temperature required to remove water and organic matter from the substrate surface (for example, 100℃ or higher), the temperature range where the expansion coefficients of the substrate and film are similar, the temperature that is suitable for the growth rate of film-like particles, and the temperature that does not decompose the compound, etc. considered and selected. The high frequency power directly and proportionally contributes to the amount of deposition per unit time, so it is not a big deal, but once it reaches a certain point, the energy of the ions that contribute to spatter becomes saturated, so it is usually 1 to 5 KW. The sputtering time is determined within a range depending on the desired film thickness. The above-mentioned high-purity argon gas is usually used as the gas atmosphere. This is because an inert atmosphere is required to obtain the same produced film material as the target material. Usually, in this way, evaporative gases and residual gases from the sputtering chamber walls are suppressed as much as possible, and in particular, active gases are avoided as impurities. For example, when obtaining an active silicon resistor by sputtering, the conventional method uses a sintered body of silicon carbide as the target material, a substrate temperature of 700°C, and high-frequency power.
The sputtering time was 7 hours at 2.0KW, sputtering gas pressure x 10 ^-5 Torr, and a gas atmosphere of 99.9999% argon gas. This is an example of obtaining a thin film resistor with thermistor characteristics (negative resistance coefficient with respect to temperature). It was also very difficult to control. Furthermore, the decrease in resistance value slowed down from around 7 hours of sputtering time, and it was difficult to obtain a smaller resistance value. Furthermore, since the shape of the element (see drawing) is determined by the relationship between the area between the electrodes and the specific resistance of the film, if the specific resistance is large, the practical resistance value range (for example, 1 to 500KΩ at a temperature of 50℃) However, it has been difficult to obtain miniaturized devices. Similarly, when used in resistors and the like, conventional methods have the disadvantage that sputtering takes a very long time when attempting to obtain a product with a small resistance value. For this reason, a large amount of materials, energy, etc. are used, leading to the disadvantage of high costs. Another conventional method is called reactive sputtering or chemical sputtering. The purpose of what has been described so far has been to suppress the reaction with ordinary sputtering, but the effect of reactive gas during reactive sputtering is actively utilized to perform sputtering in an atmosphere of reactive gas. , produce thin films of oxides, sulfides, carbides, etc. Although an active gas is used for the purpose of the reaction, in many cases an inert gas is also mixed. For example, when particularly large area targets are required, materials that are difficult to obtain in bulk, such as metal oxides, are produced by reactive sputtering of metal targets in the presence of partial pressures of oxygen. When obtaining a Ta ₂ O ₅ film, sputtering is performed using a Ta target in an (Ar+O ₂ ) gas atmosphere. In addition, MnO ₂ production film (Mn target inAr +
O ₂ ), SiN ₄ production film (Si inAr+N ₂ ), SiO production film (Si inAr+O ₂ ), etc. In order to obtain a produced film having a composition different from that of the target substance in this way, an active gas for the purpose of reaction is used. However, the reactive sputtering method is different from the normal sputtering method in that it produces an oxide film or a nitride film on the film produced after sputtering. For example, in the case of the above-mentioned SiO ₂ production film, it is formed by sputtering a mixture of oxygen and argon at a ratio of 60 to 100 vol% using a Si target, and its volume resistivity is 10 ¹⁴ Ω-cm or more.
It has a value close to SiO ₂ . In other words, the method of the present invention, which will be described later, obtains a film having the same composition as the target material, and is different from the reactive sputtering method and belongs to the ordinary sputtering method. That is, when a silicon carbide target is used, the film obtained by the present invention can be measured by reflection electron beam diffraction,
-The equiaxed crystal structure of B-SiC was confirmed by line diffraction. Furthermore, the specific resistance of this produced film is on the order of 10KΩ-cm or less, which is also useful from the point of view of structural analysis.
It is clear that this is a normal sputtering method in which SiO ₂ is not present and the reaction is suppressed. As mentioned above, there is no report on the use of a trace amount of active gas in sputtering a carbide resistance material that belongs to an ordinary sputtering method other than the reactive sputtering method. The present invention is a method for manufacturing a carbide film resistor, characterized by sputtering a carbide resistor material by adding a small amount of air or oxygen to an inert gas. That is, the present invention is a novel method for manufacturing a carbide film resistor as described above, and provides a manufacturing method that eliminates the conventional drawbacks as described above. Examples of the present invention will be described in detail below. Example 1 The device configuration is shown in Figure 1. The electrically insulating substrate forming the resistor is a 1 ton alumina substrate with a purity of 96%.
=O.65mm was used. Next, a pattern of conductive Au--Pt paste is formed on the electrode 2 on the surface where the resistor is to be formed. This electrode pattern consists of two geometrically constructed electrodes with a width of 0.25 mm, and one electrode of the same shape facing each other between them.The distance between adjacent electrodes is 0.45 mm, and the area between each electrode is Consists of ^1.35mm2 . A resistor 3 is placed on the surface configured in this way.
formation. Next, the above substrate was used as a test piece in the following sputtering experiment. The device is a two-pole sputtering device (sputtering vacuum chamber:
^350φ
The substrate temperature was fixed at 700°C and the sputtering pressure was fixed at ×10 ^-2 Torr. The spatsuta vacuum is preliminarily evacuated to ×10 ^-6 Torr, and then a constant amount of inert gas is introduced to ×10 ^-4 Torr with air or oxygen in the inert gas in the range of >0 to 10 Vo%. Ru. Silicon carbide was selected as the resistor material, and its sintered body was used as the target. Inert gas is 99.9999% Ar
A fixed amount of gas and air was introduced at different mixing ratios, and sputtering was performed at a pressure of ×10 ^-2 Torr. The results are shown in Nos. 2 to 8 of Table 1 (all resistance values were measured under a temperature condition of 25°C). No.1 is the conventional method
This was done in an atmosphere containing only Ar gas. Also, using the same method as Nos. 2 to 8, sputtering was performed with 99.999% pure oxygen at the same mixing ratio as No. 5.
It is No.9. Furthermore, the inert gas is 99.99% pure Xe
In No. 10, sputtering was performed in the same manner as in No. 5, using air as the active gas. As is clear from this, a very small resistance value can be obtained by adding a small amount of air or oxygen to the Ar or Xe inert gas. Next, samples Nos. 1 to 10 in Table 1 were subjected to a high temperature storage test at 350℃. Leave for 1000 hours, thermal shock resistance test RT, 15 minutes ~ 350℃. After 3,000 15-minute cycles, the resistance change rate was within ±6% for both, which was no different from No. 1 in Table 1. Further, as a result of structural analysis, the resistor films No. 2 to No. 10 were found to be B-SiC with the same crystal structure as No. 1. Film thickness too
No. 1 to No. 10 had almost no difference within the range of 7 μm±7%.

【table】

[Table] Example 2 B ₄ C was selected as the target material and sputtering was performed in the same manner as in Example 1. Purity of gas atmosphere
No. 12 uses 99.9999% Ar gas as a base, No. 12 uses Ar gas as a base and adds air at the same ratio as No. 5, and No. 1 uses 99.999% pure oxygen instead of air.
It is 13. Furthermore, No. 14 is made by using Ar gas as 99.99% pure Xe gas and adding air in the same proportion as No. 5. As is clear from this, it can be seen that, as in Example 1, by adding the active gas, a small resistance value can be obtained. Next, Example 1 for samples No. 11 to 14 in the table
Similarly, leave it at high temperature. A thermal shock resistance test was conducted, and the resistance change rate was within ±10% in both tests, which was the same as No. 11 in Table 1. Moreover, the resistor films of Nos. 12 to 14 had a rhombohedral crystal structure according to structural analysis, which was the same crystal structure as No. 11. There was almost no difference in film thickness between Nos. 11 to 14 within the range of 7 μm±7%. As can be seen from the above results, in the method of sputtering carbide materials, it is possible to obtain a very low resistance value by adding a small amount of air or oxygen to the inert gas. This means that if the same resistance characteristics are obtained, the device can be made extremely compact. Furthermore, for this amount of addition, the sputtering time can be easily controlled such as resistance adjustment in a short time, and the sputtering time and the cost of consumable parts are reduced, making it possible to obtain an inexpensive product. Furthermore, the B constant when obtaining thermistor characteristics had almost the same tendency as the resistance value, indicating that the addition of air or oxygen had a large effect.

[Brief explanation of the drawing]

The figure is a perspective view of an embodiment of a device using the method for manufacturing a carbide film resistor of the present invention. DESCRIPTION OF SYMBOLS 1... Alumina substrate, 2... Electrode, 3... Resistor formation part.

Claims (1)

[Claims] 1. A method for manufacturing a carbide film resistor, which comprises sputtering a carbide resistor material by adding a small amount of air or oxygen to at least an inert gas. 2. The method for manufacturing a carbide film resistor according to claim 1, wherein the carbide resistance material is silicon carbide or boron carbide. 3. The method for manufacturing a carbide film resistor according to claim 2, wherein the amount of air or oxygen is at least in the range of 0 to 10 Vo% based on the inert gas.