JPS6218731A - Semiconductor device - Google Patents

Abstract

PURPOSE:To optimally achieve the performance of a circuit by forming a thin film resistor by exposing the upper surface on an insulating film, and altering the superposing amount of wiring to be superposed to form an arbitrary resistance value for forming an analog circuit. CONSTITUTION:A metal resistance material is deposited on an SiO2 film 7 of an Si substrate 6, and the material, thickness and width are set to forma resistor 5. The upper surface is exposed to form an interlayer insulating film 8. A transistor region 2 and a peripheral region 4 are formed in an impurity diffused layer. The superposing amount La with one resistor 5 of aluminum wirings 10 is regulated to set the distance Lb between paired wirings, thereby obtaining an arbitrary resistance value. Accordingly, the resistance value is so set as to sufficiently achieve the performance of an analog circuit, and a responding time to a user can be shortened in case of forming a circuit configuration.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a semiconductor device, and more particularly to a semiconductor device suitable for application to an analog type or analog built-in type gate array.

[Conventional technology]

In general, gate arrays consist of element elements mainly composed of impurity diffusion layers formed on a semiconductor substrate, and the wiring pattern of aluminum etc. that connects these element elements can be changed according to the user's desired function and performance. A circuit can be constructed.

This gate array has so far been used in digital circuits, but in recent years it has become necessary to incorporate analog elements into semiconductor devices, and gate arrays for analog applications or gate arrays with built-in analog (referred to as analog masters) have been proposed. ing.

Incidentally, this type of gate array employs a configuration in which a resistor that constitutes a part of the circuit is constructed from an impurity diffusion layer formed on a semiconductor substrate, and wiring is connected to this impurity diffusion layer. For example, as shown in FIG. 5<a), the semiconductor substrate 21
A resistive layer 23 with impurities diffused therein is formed in the epitaxial layer 22 of the resistor layer 23, a plurality of contact holes 25 are formed in the insulating film 24 formed on the surface of the resistive layer 23, and a wiring 26 made of aluminum or the like is connected through the contact holes 25. This constitutes a resistor R, which constitutes an analog circuit.

[Problem that the invention seeks to solve]

In the conventional semiconductor device described above, since the contact hole 25 is provided as a common component of the gate array, the value of the resistance R is set by changing the pattern of the aluminum wiring 26. For example, in order to reduce the resistance value from the state shown in Figure (a), one side of the aluminum wiring 26 is extended to change the contact hole 25 for connection as shown in Figure (b).
4 is shortened to reduce the resistance value.

However, with this configuration, the resistance value can only be set to discrete (stepwise) values, so it is difficult to realize an optimal design of the analog circuit. In particular, in the analog gate array mentioned above, the resistance that forms part of the analog circuit is an important element that determines the analog performance, such as the bias and gain of the amplifier, or the threshold value of the comparator. Voltage, further A/D, D/
The accuracy of the A converter is directly determined by this resistance value. Therefore, if the resistance value cannot be set freely, it becomes difficult to fully demonstrate the circuit performance, resulting in a decrease in the performance of the semiconductor device.

In addition, in this conventional configuration, if the resistance value is to be continuously changed, the contact hole 25 must be excluded from the common components, and as shown in FIG. It is necessary to form the contact holes 25 at different positions, which increases the response time, that is, TAT (turn around time), and reduces the advantage of the gate array.

[Means for solving problems]

In the semiconductor device of the present invention, in order to continuously change and set the resistance value constituting the analog circuit and shorten the TAT,
This resistor is composed of a thin film resistor formed on an insulating film with the top surface exposed, and the resistance value can be set by arbitrarily changing the overlap amount of the wiring formed on this thin film resistor. It is composed of

〔Example〕

Next, the present invention will be explained with reference to the drawings.

1 to 3 show an embodiment in which the present invention is applied to an analog gate array. As shown in the plan view of FIG. 3, this gate array 1 includes a transistor region 2, a resistance region 3, and the surrounding A plurality of straight strip-shaped resistors 5 are arranged in the resistor region 3.

These resistors 5 are made by depositing a thin film of a metal resistance material on an insulating film 7 such as silicon dioxide formed on the surface of a semiconductor substrate 6, as shown in the cross-sectional structure taken along line AA in FIG. The pattern is formed into straight strips. This resistor 5 can be easily formed by depositing a metal resistance material by sputtering, vacuum evaporation, or the like, and then patterning it using photolithography or the like. Moreover, the maximum resistance value can be arbitrarily set by arbitrarily setting the material, thickness, or width of the thin film. The glabellar insulating film 8 formed on the resistor 5 is patterned to expose the upper surface of the resistor 5. In the figure, reference numeral 9 denotes an impurity diffusion layer forming the transistor region 2 and the peripheral region 4.

In the gate array 1 constructed in this way, as shown in FIG. 2, wiring 10 made of aluminum or the like is patterned so as to be directly deposited on the resistor 5. As shown in FIG.

At this time, if the wiring 10 is small (both sides are connected to the resistor 5),
An arbitrary resistance value can be obtained by changing and adjusting the overlapping amount (overlapping 1) La and setting the distance Lb between the pair of wirings. Therefore, it is possible to continuously change the value of the resistor that constitutes a part of the analog circuit (not shown), and adjust the bias and gain of the amplifier, the threshold voltage of the comparator, and the accuracy of the A/D and D/A converter. etc. can be designed with high precision, and the performance of analog circuits can be fully demonstrated.

In addition, in this configuration, any resistance value can be obtained by simply changing the pattern of the wiring 10 and changing the amount La by which the wiring IO overlaps the resistor 5. It is also possible to prevent an increase in TAT when configuring a circuit.

Further, FIG. 4 shows the analog built-in gate array 11, where 12 is an analog area, 13 is a digital area, and 14 is an analog area.
is the peripheral area, and the resistor 1 is placed in this analog area 12.
5 is arranged. This resistor 15 is the same as the previous example, and a metal resistance material is formed into a thin film, and an arbitrary resistance value that can be continuously changed can be obtained by changing and setting the amount of overlap of the wiring deposited thereon. I can do it.

Here, in each of the above embodiments, since the resistor is made of a metal resistance material, it is excellent in terms of relative value ratio, temperature characteristics, and power supply voltage characteristics. Further, polysilicon may be used as the resistor instead of the metal resistive material. Further, the planar pattern shape of the resistor is not limited to a straight strip shape, but may be formed in various shapes such as an L-shape or a U-shape.

〔Effect of the invention〕

As explained above, the present invention configures the resistor of an analog type gate array or a gate array with built-in analog by a thin film resistor formed on an insulating film of a semiconductor substrate, and overlaps the wiring deposited on the resistor. Since it is possible to obtain an arbitrary resistance value that can be continuously changed by changing the amount, it is possible to realize the optimal and highly accurate performance of analog circuits, and it is also possible to prevent an increase in the TAT of the gate array. can.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of the semiconductor device of the present invention, FIG. 2 is a similar view to FIG. 1 with wiring, FIG. 3 is a plan layout thereof, and FIG. 4 is a plan layout of a modified example. , FIGS. 5(a), 5(b), and 5(c) are sectional views for explaining the conventional structure and its problems. 1.11... Gate array, 2... Transistor region, 3... Resistance region, 4... Peripheral region, 5... Resistor, 6... Semiconductor substrate, 7... Insulating film , 8...
Interlayer insulating film, 9... Impurity diffusion layer, 10... Wiring,
12...Analog domain, 13...Digital domain, 1
4... Peripheral region, 15... Resistor, 21... Semiconductor substrate, 22... Epitaxial layer, 23... Resistance layer, 24... Interlayer insulating film, 25... Contact hole,
26...Wiring, L a...Overlap amount. Agent Patent Attorney Susumu Uchihara...j,...,1
・7゛・・・Pad- Figure 1

Claims (1)

[Claims] 1. In a semiconductor device such as a gate array that constitutes at least a part of an analog circuit, a thin film resistor in which a resistor that constitutes a part of the analog circuit is formed on an insulating film on the surface of a semiconductor substrate with its upper surface exposed. What is claimed is: 1. A semiconductor device characterized in that the resistance value can be continuously changed by arbitrarily changing and setting the amount of overlap of wirings deposited on the thin film resistor.