JPS5984502A - Method of forming thin film resistance pattern - 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 The present invention relates to a hybrid integrated circuit, and particularly to a method for forming a highly reliable and high quality thin film resistor pattern.

Conventionally, for example, the manufacturing method for tantalum thin film circuits involves sequentially depositing a tantalum layer for resistors and titanium or nichrome/palladium/gold layers for conductors on an insulating substrate by the vine method, and then depositing the metal on an insulating substrate. The layers are selectively processed in one step by photoresist treatment and wet etching techniques to form the desired conductor pattern and resistor pattern, and finally the resistor pattern is laser trimmed or anodized to form the desired resistor. By adjusting the value, thin film circuits are manufactured.

However, according to the above manufacturing method, the problem of side etching, which is more difficult to avoid than with a wet etching solution, affects the pattern accuracy of the pattern.

Moreover, there is a phenomenon in which side etching progresses particularly in the portion directly connected to the conductor portion of the resistor pattern, making it extremely difficult to form a uniform pattern.

This phenomenon mainly occurs during immersion in an etching solution, and the cause is the flow of heat related to the etching reaction. That is,
:r: When the temperature of the etching solution is raised to increase the reaction rate, the reaction is endothermic; in etching at room temperature, the reaction part continues the reaction while absorbing heat from its surroundings; The portion of the resistor that can acquire a larger amount of heat has a correspondingly larger amount of reaction, and side etching becomes more pronounced. Since the metal pattern part is sandwiched between the resist and the ceramic substrate, heat flows in the thickness direction.
Therefore, during immersion in the etching solution, heat transfer occurs immediately after the substrate is ejected along the metal pattern portion. At this time, the side etch of the tantalum film under the conductor has good adhesion to the other, so compared to the side etch of the tantalum film under the resistive resist, only the side etch of the tantalum film under the conductor progresses. A one-dimensional temperature gradient along the pattern and the accompanying flow of heat are generated to the resistor pattern.As a result, the portion of the resistor pattern that is directly connected to the conductor consumes a particularly large amount of heat, resulting in side etching. It becomes noticeable.

In the worst case, disconnection failures occur in the pattern, and initial resistance value failures occur frequently due to variations in the resistor pattern width, making it impossible to perform laser trimming or color tubes for anodization.

SUMMARY OF THE INVENTION An object of the present invention is to provide a new method for forming a thin film resistor pattern that corrects the drawbacks of the above-mentioned forming methods.

That is, by making the shape of the resistor pattern dumbbell part elongated along the periphery of the conductor pattern to which the resistor pattern is connected by a constant width of about 20 μm, the side etching at the dumbbell part around the conductor pattern is similar to that of the resistor pattern. This is a method for forming a thin film resistor pattern using a method in which side etching proceeds simultaneously with side etching to prevent concentrated heat from flowing into the resistor pattern.

Hereinafter, a detailed explanation will be given based on examples. FIG. 1 shows the resistance pattern after etching in the case of the conventional type, and FIG. 2 shows the resistance pattern after etching in the case of the improved type according to the present invention. In the case of the conventional type, the shape of the resistance pattern 2 formed on the insulating substrate 1 becomes thinner as it approaches the conductor pattern 3 (FIG. 1). For it,
In the case of the improved type, heat consumption due to side etching at the dumbbell portion suppresses the concentrated flow of heat to the resistor pattern 2', and the thin wrinkles seen in the conventional pattern are due to the improved type. No pattern was observed at all (Figure 2).

As described above, according to the present invention, the progress of partial side etching during immersion in an etching solution is significantly improved, and a uniform pattern can be obtained.

It has become possible to manufacture commercial quality thin film resistor circuits.

Furthermore, not only when the reaction is endothermic, but also when the reaction is exothermic, the flow of heat is in the opposite direction, but the same phenomenon occurs in principle. That is, it can be generally interpreted that the heat exchangeability of the reaction must be considered as one of the partial progresses of side etching. Therefore, the present invention is not limited to tantalum thin film resistor patterns, but can be similarly applied to other metal resistor patterns in equivalent situations from the viewpoint of heat exchange performance, such as etching titanium, nichrome, etc. It is something.

[Brief explanation of the drawing]

FIG. 1 is a plan view showing the etched diameter shape of a conventional resistor pattern, and FIG. 2 is a plan view showing the shape of an improved resistor pattern after subetching using a single BAK. In the figure, 1.1'...ceramic substrate, 2.2'...mental film resistance pattern, 3.
3'...Titanium or nichrome/palladium/gold composition film conductor part.

Claims (1)

[Claims] In the process of forming a desired thin film resistor pattern by photoresist treatment and wet etching treatment of the conductive metal thin film formed on the insulating substrate, the resistor dumbbell portion is shaped to expand along the periphery of the conductor pattern. A method for forming thin film resistor turns featuring: