JPH0140515B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a thin film hybrid integrated circuit, and more particularly to means for making constant the formation voltage of a film-formed resistor.

It is difficult to control the low resistance value of resistors formed on thin film hybrid integrated circuit boards made of ceramics etc. with high precision using only film formation technology.
When an accurate resistance value is required in a circuit, trimming is performed by a physical method that removes a portion of the resistive film, or by an electrochemical method that adjusts the effective thickness without changing the pattern shape. Particularly in tantalum-based hybrid integrated circuits, chemical trimming, that is,
For example, tantalum nitride (Ta) deposited on a circuit board.
-N) film is selectively etched to form a resistor pattern, and a tantalum oxide (Ta ₂ O ₃ ) film of a predetermined thickness is chemically formed on the surface of the pattern.
A method of obtaining a desired resistance value by reducing the thickness of the N film is widely used. However, in the chemical trimming process, a plurality of tantalum-based resistors are formed on one circuit board, and in particular, a large number of tantalum resistors are formed on a large board, such as a hybrid integrated circuit used in submarine repeaters.
Highly reliable, high-precision resistors that are formed in numbers of 10 to several 100 pieces have a wide variety of pattern shapes and resistance values in circuit design, and also take into account variations in Ta-N film thickness between manufacturing lots. There is a need. Therefore, in the past, after measuring the resistance value of each resistor pattern, which was designed to be approximately constant with respect to the resistor resistance value, the formation voltage at which a Ta ₂ O ₅ film of the required thickness was formed was determined based on the measured value. (for example, 15 Å/V). Therefore, not only many types of formation voltages are required, but also the Ta ₂ O ₅ (derivative) film may be destroyed if the formation voltage for low anti-antibody patterns with short chemical growth is increased to about 130V or higher. It was hot.

An object of the present invention is to eliminate the above-mentioned problems, and the object is to provide a thin film hybrid integrated circuit in which a plurality of resistors are formed by chemical trimming means, in which each resistor pattern has a conventional width w and a conventional length l. The present invention is achieved by providing a thin film hybrid integrated circuit characterized in that at least one of the above and the adhesion thickness t is adjusted to make the resistor pattern formation voltages of various constants constant. Ru.

The present invention will be explained below using the drawings.

FIG. 1 is a plan view (a) and a cross-sectional view (b) showing an example of a resistor film formed on a thin film hybrid integrated circuit board. 3 is a tantalum chemical (Ta ₂ O ₅ ) layer; 4 is a nichrome (NiCr) layer laminated on both ends of the Ta-N layer 2; is each
A gold (Au) electrode layer laminated on the NiCr layer 4 is shown. However, NiCr layer 4 is Ta-N layer 2 and Au
It is provided as an adhesive medium with the electrode layer 5.
The resistance value R of the resistor 6 configured in this way is determined by the length l, width w, and thickness t of the Ta-N layer 2 between the opposing electrode layers 5, and usually the total width w of the Ta-N layer 2. The length l′ of the Ta ₂ O ₅ layer 3 formed across the Ta ₂ O ₅
Ta-N layer thickness reduced by layer 3
determined by t′. In general, the Ta ₂ O ₅ layer length l' is slightly shorter than the Ta-N layer length l, and the position of the chemical resist forming mask is shifted slightly so that both ends are slightly separated from the electrode layer 5. Even if such a situation occurs, it is possible to obtain an accurate Ta ₂ O ₅ layer length l'. Furthermore, the Ta ₂ O ₅ layer 3 whose thickness is controlled by the formation voltage V has a thickness of about 1/3 of that thickness.
By reducing the thickness t of Ta-N layer 2 by the amount, Ta ₂ O ₅ layer 3
A Ta-N layer thickness t' is formed.

That is, the resistance value R with the specific resistance of the Ta-N layer as ρ
As is widely known, R=ρ・(l−l′)/w・t+ρ・l′/
w・t′=ρ/w・{(l−l′)/t+l′/t′}. While the thickness t' with respect to the resistance value R has conventionally been treated as one variable that is adjusted by the formation voltage V, one means related to the present invention is to adjust the thickness t' based on the conventional resistance value R setting dimension. The purpose is to make t' a constant and correct the resistance value R by the width w and length l. That is, a Ta-N layer is formed on the substrate 1 to a uniform thickness t.
When forming each resistor pattern having a plurality of various shapes using etching means, the pattern width w and the pattern length l are corrected and adjusted by slightly increasing or decreasing one or the other from the conventional dimensions. By doing so, the thickness t' becomes constant, and the formation voltage V of each resistor pattern becomes constant.
However, in this case, the ratio between the resistance value of the resistor pattern and the value of the resistor after chemical formation differs depending on the shape of the resistor.

On the other hand, as a result of measuring the resistance value of each resistor pattern before chemical trimming, the pattern thickness t may be larger than the expected value due to variations between manufacturing lots. In that case, the conventional concept of using the resistor thickness t' after formation as a variable is that the formation voltage V is close to the dielectric (Ta ₂ O ₅ ) layer breakdown voltage (approximately 130 V). Other means related to the present invention are shown in the main process explanatory diagrams in one embodiment of FIGS. 2a to 2d.

In FIG. 2a, a thin film hybrid integrated circuit board 11
Tantalum nitride (Ta-N) is deposited on top by conventional means.
A layer 12, a nichrome (NiCr) layer 13, and a gold (Au) electrode layer 14 are laminated in a predetermined manner. Next in the second
As shown in FIG. b, covering at least the electrode layer 14,
After depositing a resist layer 15 so that the Ta-N layer 12 between the opposing electrode layers 14 is exposed, the surface of the exposed Ta-N layer 12 is etched with a hydrogen fluoride (HF) aqueous solution or the like. do. however,
The amount of etching is such that the load voltage when forming the part is 130V or less. Then the second
As shown _{in FIG} .
The resist layer 15 is removed to complete the resistor 17 shown in FIG. 2d.

In the above description of the present invention, the present invention is divided into one means and other means, but each means is not applied exclusively to each other, and the one means and the other means are not applied exclusively to each other. One companion of the means can be applied to the creation of thin film hybrid integrated circuits. Furthermore, it is obvious that the other means described above can be applied to only some of the plurality of resistor patterns formed on one circuit board, or to all remaining parts.

According to the present invention as described above, when chemically trimming a film resistor, it is possible to reduce the load voltage to below the breakdown voltage of the dielectric layer, which not only improves the manufacturing yield but also The practical effect of increasing the reliability of the layer is remarkable.

[Brief explanation of drawings]

FIG. 1 is a plan view a showing a membrane resistor and a cross-sectional view b thereof for explaining one means according to the present invention.
FIG. 2 is a main process diagram for explaining another means related to the present invention. In the figure, 2 and 12 are tantalum nitride (resistance) layers, 3 and 12 are chemical conversion (Ta ₂ O ₅ ) layers, and 5 and 14 are tantalum nitride (resistance) layers.
indicates a gold (Au) electrode layer, and 6 and 17 indicate resistors.

Claims (1)

[Claims] 1. In a thin film hybrid integrated circuit in which a plurality of resistors are formed by chemical trimming means, at least one of the conventional width w, conventional length l, and deposition thickness t of each resistor pattern is adjusted. A thin film hybrid integrated circuit characterized in that the resistor pattern forming voltages of various constants are made constant.