JPS626703Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a semiconductor device, and particularly to an integrated circuit using impurity diffusion technology and photoetching technology.

In recent years, integrated circuits have continued to penetrate into various application fields due to rapid advances in manufacturing technology and developments in circuit design technology. In integrated circuits, the performance, limits, and manufacturing error distribution of active elements (e.g., transistors, diodes, etc.) and passive elements (e.g., resistors, capacitors, etc.) that are constructed on the same substrate using impurity diffusion technology and photolithography technology. As understanding of these elements deepens, circuit design techniques using these devices continue to develop. This trend can be seen in the fact that integrated circuits are beginning to be used in fields that were previously unthinkable as applications for integrated circuits.

In general, as for resistors using impurity diffusion technology and photoetching technology, the absolute accuracy of the resistor varies due to variations in manufacturing technology, and is thought to vary by as much as ten or more percent, as is well known. Therefore, in circuit design, it is necessary to take into account even if the absolute accuracy of the resistance varies by more than ten percent, so that the required functions are satisfied.

However, since the resistors used as integrated circuit elements are manufactured close to each other on the same substrate, it is relatively easy to reduce the relative accuracy between the resistors to a few percent or less. Furthermore, methods to improve the relative accuracy between resistors include (1) widening the resistance width of the resistors;

(2) Reduce the connection resistance between the resistor and the wiring conductor.

Measures such as these are generally considered.

The first measure is that fluctuations in the resistance values of the resistors caused by errors related to photolithographic techniques in the manufacturing process cause a deterioration in the relative precision between the resistors. As a countermeasure to this, by widening the resistance range of the resistor,
This is a method for reducing the influence of errors caused by photolithography on the resistor end face on the resistance value.

The second measure is to reduce the resistance value fluctuation of the connection resistance between the resistance and the wiring conductor to a value that does not affect the relative accuracy between the resistances.

The above measures clarify the relative accuracy between resistors required in circuit design, and when integrated circuits,
The general method is to determine the optimal countermeasure.

In special applications using resistors, such as constructing a high-precision voltage divider circuit using a resistor network or constructing multiple high-precision constant current circuits using a resistor ladder network, the Strict requirements may be placed on ratio accuracy.

An example of an integrated circuit of a resistor network, which requires strict ratio accuracy between resistors, is shown in Figure 1. Figure 1 shows an example of a resistor ladder network constructed using impurity diffusion technology and photolithography technology. In Figure 1,
This is an example of a resistor ladder circuit formed using nine unit resistors 1, wiring conductors 2 for interconnecting the unit resistors 1, and two pseudo resistors 3, and the equivalent circuit diagram is shown in FIG.

The integrated circuit shown in Figure 1 uses the same method for extraction to prevent errors caused by the connection resistance between the resistor and the wiring conductor, and the photo-etching technique This is an example of preventing deterioration in the relative accuracy between resistors involved in impurity diffusion technology.

In the example shown in Fig. 1, which is an integrated circuit to realize the equivalent circuit diagram shown in Fig. 2, the resistance ladder network is composed of a plurality of unit resistors 1, so a resistance ladder network with excellent ratio accuracy is realized. can.

Next, consider integrating two types of resistor ladder networks with different resistance values of unit resistors. At this time, it is a commonly used technique to integrate two types of resistor ladder networks in close proximity. This is because when creating an integrated circuit, it is necessary to isolate active elements and passive elements using impurity diffusion technology, and the larger the area where the elements are isolated, the higher the degree of integration.

In FIG. 3, two types of unit resistors 31 and 32 are shown.
An example of two types of resistor ladder circuit networks using the following is shown (the interconnection patterns of the resistors are omitted here). One piece of the condensed resistors 33 and 34 are provided to maintain the ratio accuracy between the unit resistors 31 and 32, respectively. In FIG. 3, wiring conductors for interconnection between resistors are not shown in order to simplify the drawing, but wiring conductors as shown in FIG. 1 are generally used.

This is an example of improving the ratio accuracy between the unit resistors constituting each resistance ladder network using the condensed resistors 33 and 34 in FIG. It is clear that the use of individual circuits is not preferable because it leads to deterioration of the degree of integration when integrated circuits are fabricated.

The present invention improves the above-mentioned drawbacks and provides an integrated circuit that can maintain ratio accuracy between each unit resistor by using only one condensed resistor. An integrated circuit that maintains relative accuracy can be realized simply by using resistors.

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 4 is an explanatory diagram of an embodiment of the present invention. Fourth
The figure is an explanatory diagram of two types of resistance ladder circuit networks constituted by a first unit resistor 41, a second unit resistor 42, and a condensed resistor 43. Note that the wiring conductors are omitted in order to simplify the diagram.
Same as the figure.

Since the feature of the present invention lies in the condensed resistor 43, the condensed resistor 43 will be explained.

The condensing resistor 43 is a condensing resistor which is cut at the midpoint of the unit resistors 41 and 42 and connecting the right half of the unit resistor 41 and the left half of the unit resistor 42. In order to maintain the ratio accuracy between the resistors 41 and 41, the unit resistor 41 side has the same shape as the unit resistor 41, and the unit resistor 42 side has the same shape as the unit resistor 42. Therefore, it is extremely effective because it is possible to improve the degree of integration while maintaining the relative accuracy of the unit resistors 41 and 42 without using two fibrillated resistors.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of a conventional integrated circuit, FIG. 2 is an equivalent circuit diagram of FIG. 1, FIG. 3 is an explanatory diagram of a conventional integrated circuit, and FIG. 4 is an explanatory diagram of an embodiment of the present invention. 1...Resistor, 2...Wiring conductor, 3...Fragmented resistor, 31, 32, 41, 42...Unit resistor,
33, 34, 43... Condensation resistor.

Claims (1)

[Scope of utility model registration request] A third resistor is provided between the first resistor and the second resistor, the third resistor has the same shape as the left half of the first resistor adjacent to the right, and the second resistor is adjacent to the left. A semiconductor device characterized by having the same shape as the right half of.