JPS6322042B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for manufacturing a carbide film resistor in which a thin film of carbide resistor material is formed on an electrically insulating substrate surface by sputtering. It is well known that this type of sputtering has traditionally been used as a method for manufacturing electronic components such as resistors and capacitors by thinning target materials such as conductors, semiconductors, dielectrics, and insulators. be. Sputtering is a process in which ionized gas molecules
This is a phenomenon in which the target material is accelerated by an electric field and collides with the target electrode (material), and the target material is released in the form of molecules or atoms. Sputtering is broadly classified into ordinary sputtering, which inhibits reactions, and reactive (or chemical) sputtering. The former is a method in which a rare gas is used to make the sputtering gas atmosphere particularly inert, and at least the desired formed film can be obtained with a composition similar to that of the original target material. The latter method actively utilizes the effect of reactive gas during sputtering, and is a method in which sputtering is performed in a sputtering gas atmosphere containing reactive gas. Most of these produced films are obtained in the form of oxides, nitrides, etc., and are often at least electrically insulators or similar to them. For example, by sputtering the dielectric materials mentioned above, Ta ₂ O ₅ , SiO ₂ ,
It is widely known for obtaining thin film dielectrics such as Si ₃ N ₄ and TiO ₂ . Their volume resistivity is at least 10 ¹³ Ωcm or more. In addition, oxygen, nitrogen, etc. are used as these reactive gases, and are usually added at a ratio of 50 vol% or more to the rare gas. Further, when making a carbide resistor belonging to a semiconductor into a thin film, ordinary sputtering is usually used. For thinning carbide resistors, the usual substrate temperature is 700℃, high frequency power is 2KW, and sputtering gas pressure is
The sputtering time was 4 to 8 hours in an argon atmosphere of 10 ^-2 Torr and 99.9999% sputtering gas.
This is an example of a method for forming a produced film with NTC thermistor characteristics, but this method has a large specific resistance and is also affected by residual gas in the sputtering chamber, resulting in the resistance value and thermistor constant, which are the basic characteristics of a thermistor, being affected. Stabilization was extremely difficult. Further, regarding the sputtering time dependence of the resistance value, it was difficult to obtain a lower resistance value because the resistance temperature characteristic changed depending on the sputtering time. That is, there was a drawback that the resistance value was not necessarily inversely proportional to the film thickness. Furthermore, the shape of the element (see Figure 1) for a given resistance value is
Since it is determined by the relationship between film thickness and specific resistance, if the specific resistance is large, the practical resistance value range (50
When measured at °C: 1 to 1000KΩ), it was difficult to obtain a miniaturized element. Therefore, the material
This led to the disadvantage of high costs due to the large amount of energy and labor required. When a carbide resistor material is sputtered in a sputtering atmosphere containing a large amount of impure gas such that the reaction product of the carbide material and impure gas becomes an insulator, the reaction with the impure gas causes the resulting film to have a large amount of insulating properties. It is clear that the reaction products are mixed and become an electrical insulator. Focusing on this, we researched the manufacturing method of carbide film resistors and found that a sufficiently practical carbide film resistor could be created by adding a very small amount of impurity gas. Furthermore, as a result of research, when a predetermined substrate temperature was set and the above manufacturing method was used, each characteristic effect of adding impurity gases was obtained even for the predetermined substrate temperature. It is clear that these belong to reactive sputtering because the volume resistivity increases as the impurity gas concentration increases and eventually they become insulators. That is, the present invention aims to provide a novel and industrially useful method for manufacturing a carbide film resistor that eliminates the above-mentioned conventional drawbacks by utilizing such reactive sputtering. In the present invention, by setting the substrate temperature at 500 to 800°C and adding a small amount of impurity gas to at least the rare gas in the sputtering gas atmosphere, the produced film is affected by the reaction of the impurity gas and the specific resistance increases. This method of manufacturing a carbide film resistor is characterized by sputtering a carbide resistance material onto the surface of an electrically insulating substrate within the range of addition. Hereinafter, a detailed explanation of the present invention will be given with reference to Examples. Example 1 The configuration of a resistor element is as shown in FIG. 1, and an alumina substrate 1 (thickness: 0.5 mm) with a purity of 96% was selected as an electrically insulating substrate on which a resistor film was formed. Next, on the surface where the resistor film is to be formed, the electrode 2 is made of Ag, Au, Ag-
A sintered body of conductive paste such as Pd or Au-Pt is formed. This two-electrode pattern is configured in a geometric pattern and consists of two electrodes with a width of 2.0 mm and one electrode of the same size facing each other, and these three electrodes are arranged in a geometric pattern. The distance was 0.3 mm. A desired resistor film is formed on the surface of the substrate configured in this manner. In the following experiments, the substrate prepared above was used as a test piece. The sputtering device is a high-frequency bipolar type with a vacuum chamber.
A general-purpose type consisting of 350φ×250hmm was used. The sputtering setting conditions are: high frequency power 2.0KW sputtering time 2.0Hrs, board temperature setting 500, 650, 750,
A temperature of 800°C and a sputtering pressure of ×10 ^-2 Torr were selected. First, the sputter vacuum chamber is sufficiently evacuated to ×10 ^-6 Torr, and then a predetermined amount of the selected impurity gas is added to the rare gas, and the total gas pressure is reduced to ×10 -6 Torr.
A constant amount is introduced up to 10 ^-4 Torr. Next, a sintered body of silicon carbide was selected as the carbide resistor material for the target material, 99.9999% pure argon was used for the rare gas, and 99.9999% pure argon was used for the impure gas.
99.999% nitrogen, 99.999% purity oxygen, 99.99% purity
Carbon dioxide, 99.99% pure carbon monoxide, air in bulk, or a representative mixed gas from these groups (78.50% nitrogen, 21.45% oxygen, 0.05% carbon dioxide)
% concentration formulation) was used. These rare gases and impurity gases were introduced in predetermined amounts with varying partial pressure ratios, and sputtering was performed at a sputtering pressure of ×10 ^-2 Torr. When obtaining a silicon carbide resistor film with excellent heat resistance, the substrate temperature is preferably 500 to 800°C. This is because at a substrate temperature of 500° C. or lower, the heat resistance of the obtained silicon carbide resistor film deteriorates, making it impossible to obtain thermal stability as described below. Further, a substrate temperature of 800° C. or higher is too high for ordinary sputtering equipment to be practical. In other words, when the temperature reaches such a high temperature, the area around the vacuum chamber of the sputtering apparatus is heated, so that it becomes necessary to make the vacuum chamber larger. Alternatively, the cooling of the vacuum chamber may be made stronger. However, it is inevitable that the device will become larger or have a more complicated configuration. Therefore, it is natural that a sputtering apparatus that takes such considerations can have a substrate temperature of 800° C. or higher. However, even when a silicon carbide resistor film is formed at a substrate temperature of 500° C. or lower, it is naturally useful for uses that do not require high heat resistance. The resistance-temperature characteristics of each of the temperature-dependent silicon carbide film resistance elements thus created were measured in an oil bath at 50°C. The results are shown in Figures 2, 3, 4, 5, 6, and 7.
Shown in the figure. Figure 2 shows the relationship between the added amount, resistance value (measured at 50°C), and specific resistance (impurity gas addition effect) when the impure gas is nitrogen; Figure 3 shows the relationship between oxygen and nitrogen; is the case of carbon dioxide, FIG. 5 is the case of carbon monoxide, FIG. 6 is the case of air, and FIG. 7 is the case of the prepared mixed gas. Points A to D in Figures 2 to 7 are the conventional method, with the sputtering gas atmosphere being only the rare gas argon, and the substrate temperature being 500℃ point A and 650℃ point B.
point, 750°C point, and 800°C point D, and other setting conditions were created in the same manner as above (hereinafter referred to as blank). Curves A to D in Figures 2 to 7 show the effect of the substrate temperature and impurity gas addition according to the present invention. is the board temperature 750
℃ and d are for the case where the substrate temperature is 800℃. The thickness of these films was within 2 μm±8%, and no difference was observed from the blank. From Figures 2 to 7, depending on the type of impurity gas selected, the amount added, and the selected substrate temperature, there is a tendency for characteristic addition effects, but it is possible to obtain resistance values or resistivity over a wide range. I understand. In other words, by controlling the amount of impurity gas added at the same substrate temperature setting as the blank, the characteristics that could only be obtained in the blank range shown in points A to D with the conventional method can be obtained in the range A to D shown in FIGS. 2 to 7. It can be seen that the characteristics can be obtained over a wide range as shown in the curve. This means that the resistance value and specific resistance are
This shows that it can be easily controlled over a wide range from extremely low to high, and that a stable film resistor can be obtained by adjusting the amount of impurity gas added. In addition, when the noble gas is replaced with 99.99% pure xenon, 99.99% pure neon, and 99.99% pure krypton from argon, and the amount of each impurity gas is fixed at 3.0 vol%, it is the same as when using argon as described above. Film formation was performed under these conditions, and the effects of the rare gas and substrate temperature were investigated. The results are shown in the table. Table No. 1~
3 shows the effect of rare gas on nitrogen when the substrate temperature is set to 650 and 750°C.Similarly, Nos. 4 to 6 show oxygen at the substrate temperature of 650 and 750°C, and Nos. 7 to 9 show the effect of the rare gas on nitrogen.
Carbon dioxide at 500 and 650℃, No.10 to 12 are substrate temperatures
Carbon monoxide at 500 and 650℃, No.13 to 15 are substrate temperatures
Air at 650, 750℃, No. 16 to 18 at substrate temperature 650, 750℃
This is the case for a representatively selected gas mixture (same as the formulation described above) at °C. The thickness of the produced film at this time is
It was within 2 μm±8%, and no difference was observed from the blank. By comparing the results in the table with the results at the same substrate temperature when 3.0 vol% of each impurity gas was added to argon shown in Figures 2 to 7, the same results were obtained when the rare gases were xenon, neon, and krypton. It can be seen that the addition of impure gas has an effect depending on the substrate temperature. Here, only substrate temperatures of 500 and 650 degrees Celsius or 650 and 750 degrees Celsius are shown, but similar effects are shown in other ranges as well.

[Table] Next, each of the film resistors created in this way, including the blank, was subjected to a high temperature storage test (at 350℃).
Thermal shock resistance test (3000 cycles with one cycle consisting of holding at room temperature for 15 minutes and holding at 350°C for 15 minutes) was carried out. As a result, the rate of resistance change is almost ±
Within 8%, no difference from the blank was observed. Similar studies were also attempted on carbides other than silicon carbide such as boron and zirconium compounds, but peeling of the film occurred in some areas during thermal shock resistance tests. However, if the thermal shock is gentle, the above-mentioned peeling of the film does not occur. For this reason, silicon carbide is suitable for applications that involve large thermal shocks, but boron and zirconium compounds are also suitable for applications that involve only small thermal shocks. The claimed range of the amount of impurity gas added according to the present invention is the range of each impurity gas represented by the range of 10 ⁵ Ωcm or less from the minimum value of each resistivity of the curves A to D of FIGS. 2 to 7. It is indicated by the addition range. specific resistance
The reason why it is set to 10 ⁵ Ωcm or less is based on the fact that the practical resistivity of such a carbide film resistor is 10 ⁵ Ωcm or less. In this case, the most useful thing is the resistivity,
The resistance values shown in the examples are based on the electrode configuration shown in FIG. Therefore, it is clear that by finely structuring this electrode configuration using photolithography, electron beam, or X-ray lithography technology, a sufficiently practical resistance value can be achieved even in the case of the resistivity shown here. . If more than this, for example, 50% or more of impurity gas is added, the resulting film has a composition close to that of oxides or nitrides, which are usually used as dielectrics or insulators. It is clear that reaction-generating sputtering in which a reaction-generated film is obtained by adding a large amount of impure gas as described above and the present invention are on the same extension line from the electrical characteristics, and are reactive sputtering. However, regarding the method of manufacturing a carbide film resistor according to the present invention, there is no report that a useful carbide film resistor can be obtained by sputtering at a selected substrate temperature and by adding a small amount of impurity gas to cause a reaction. . In addition, the reason why the optimum range of the amount of impure gas added is determined from the range of the amount of impurity gas added that is represented by the minimum value in the resistance value and specific resistance curves shown in A to D is that during such reactive sputtering, This is because the minimum value of resistivity occurs at the added amount. The amount of each impurity gas added that reaches this minimum value is approximately several percent. A production method below this range has the feature that, contrary to the present invention, the amount of impurity gas added increases and the specific resistance or resistance value decreases, and the produced film also has the same composition as the target material that does not contain reaction products. It is a membrane with From this, it is clear that this production method can be distinguished from the method of the present invention.

[Brief explanation of the drawing]

FIG. 1 is a film diagram showing the structure of a carbide film resistance element obtained by the manufacturing method of the present invention, and FIG. 2, FIG. 3, FIG. 4, FIG. 5, FIG. 6, and FIG. FIG. 3 is a characteristic diagram of substrate temperature and impurity gas addition amount in the manufacturing method of the invention. DESCRIPTION OF SYMBOLS 1... Alumina substrate, 2... Electrode, 3... Resistance film formation part.

Claims (1)

[Claims] 1. By setting the substrate temperature at 500 to 800°C and adding a small amount of impurity gas to at least the rare gas in the sputtering gas atmosphere, the produced film is affected by the reaction of the impurity gas, and the 1. A method for manufacturing a carbide film resistor, comprising sputtering a carbide resistance material onto an electrically insulating substrate surface in an additive range that increases resistance. 2. The method for manufacturing a carbide film resistor according to claim 1, wherein the rare gas is at least argon, xenon, or krypton. 3. The carbide according to claim 1, wherein the impure gas is at least nitrogen, oxygen, carbon dioxide, carbon monoxide, air, or a mixed gas of one or more selected from these groups. A method for manufacturing a membrane resistor. 4. The method for manufacturing a carbide film resistor according to claim 1, wherein the carbide film resistor material is at least silicon carbide. 5 The amount of impurity gas added to the rare gas should be the amount that increases the specific resistance of the produced film to the amount that reduces the specific resistance to 10 ⁵ Ω cm or less at least at a predetermined substrate temperature that is arbitrarily selected. A method for manufacturing a carbide film resistor according to claim 1.