JPH02277263A - Resistance network - Google Patents

Abstract

PURPOSE:To obtain a resistance-value ratio whose accuracy is high and whose temperature tracking characteristic is excellent by a method wherein a plurality of resistances formed by connecting a plurality of unit diffusion resistances of an identical shape in series or in parallel are provided via a plurality of conductive members which are formed in an identical process. CONSTITUTION:A plurality of unit diffusion resistances 2, 2', of an identical shape, of a second conductivity type are formed side by side at equal intervals inside a semiconductor substrate of a first conductivity type; a semiconductor process to form an insulating film and to form contact holes 3, 3', 5, 5' is executed. After that, conducting members 4, 4' are formed; a resistance formed by connecting the plurality of unit diffusion resistances 2, 2' in series or in parallel via the members is formed at the same time. Thereby, temperature coefficients of a plurality of resistances become nearly uniform; a temperature tracking characteristic of a resistance-value ratio between the individual resistances becomes good.

Description

[Detailed Description of the Invention] [Summary] The present invention involves forming a plurality of unit diffused resistors in parallel at equal intervals in a semiconductor substrate by a process such as thermal diffusion or ion implantation. By connecting unit diffused resistors in series or in parallel via a first conductive member and a second conductive member, a first resistor and a second resistor each having high resistance value accuracy are formed. Since the unit diffused resistors are formed in close proximity in the same photolithography process, the resistance value of each unit diffused resistor can be set with high accuracy with little resistance value deviation, and each unit diffused resistor can be set with high accuracy. Since the temperature coefficient of can be made very uniform, the resistance value ratio of the first resistor and the second resistor can be highly accurate and have excellent temperature tracking characteristics. In addition, since multiple resistor network chips can be formed on the same wafer, mass production is excellent, making it possible to manufacture resistor networks with high precision and resistance value ratios with excellent temperature tracking characteristics at low cost. .

[Industrial application field]

The present invention relates to a resistor network widely used in analog circuits, and particularly to a resistor network that is highly accurate and can obtain a resistance value ratio with excellent temperature trunking characteristics.

[Conventional technology]

02771 that requires high gain accuracy, such as an inverting amplifier circuit, a non-inverting amplifier circuit, a differential amplifier circuit, and a gain switching amplifier placed before an A/D converter (analog/digital converter). In analog circuits where relative accuracy between each resistance element is important, such as positive and negative reference voltage circuits applied to circuits, A/D converters, D/A converters (digital/analog converters), etc. Resistor networks are widely used because they offer significant improvements in adjustment time and reliability.

This resistor node work is a so-called chip resistor in which a plurality of resistors are housed in one package, and has conventionally been obtained using thick film elements or thin film elements.

Thick film resistors are made by using printing technology to create circuit patterns using paste-like materials as ink resistors.
Created by firing at 00°C.

On the other hand, thin film resistors are made of Ni on an insulating substrate such as an alumina substrate.
- It is created by forming a metal film such as Cr or Ta2N by a vacuum evaporation method or a sputtering method.

Of the two types of resistance networks mentioned above, those using the thin film resistance elements generally have higher element density than those using thick film resistance elements, have better noise and high frequency characteristics, and have a lower temperature coefficient. Since it is small and has a small resistance value deviation, it is possible to create a resistor with higher precision than the above-mentioned thick film resistor.

Furthermore, trimming by laser trimming or anodic oxidation has the advantage that it is possible to improve resistance value accuracy and lower TCP (temperature coefficient).

In particular, the resistance network using Taz N resistance elements can be trimmed with extremely high precision (±0.1% or less) by anodizing, and the TCR can be changed by controlling the amount of N2 during sputtering. Because of this, it is used in the manufacture of CR oscillator circuits with a zero temperature coefficient.

[Problem to be solved by the invention] However, there is a limit to mass production of resistive networks using conventional thin film resistive elements because of the large number of manufacturing steps such as sputtering and patterning processes using photolithography. The disadvantage was that the manufacturing cost was high.

Furthermore, due to technical constraints on pattern width (line width) control accuracy and alignment accuracy in lithography and etching technology, there are limits to the miniaturization of line widths in thin film resistive elements.
Therefore, there was also a drawback that there was a limit to miniaturization of the chip size. Furthermore, since the sheet resistance values of Ni-Cr and Ta2N are low, there is a limit to increasing the resistance in the case of thin film resistive elements (up to about 10 OKΩ). There is a problem in that a thick film resistor must be used, which is inferior to a thin film resistor and has a low element density, making it difficult to miniaturize.

An object of the present invention is to provide a resistor network that is highly accurate and provides a resistance value ratio with excellent temperature tracking characteristics, and that also has an easy manufacturing process and can be mass-produced to reduce costs.

[Means to solve the problem]

In order to solve the above-mentioned problems, the resistance network of the present invention includes a semiconductor substrate of a first conductivity type, and a resistor network formed of a plurality of resistors formed on the same substrate, and a resistor network formed of a plurality of resistors formed on the same substrate. A plurality of unit diffused resistors having the same shape and having a second conductivity type opposite to the first conductivity type are formed in parallel in the same process, and a part of the plurality of unit diffused resistors is conductive part.

It is characterized by having a plurality of resistors connected in series or in parallel through materials.

Each of the plurality of resistors is formed by, for example, connecting the plurality of unit diffused resistors in series or in parallel at arbitrary intervals through the conductive member.

[For production]

The operation of the means of the invention is as follows.

In a semiconductor substrate of a first conductivity type, a plurality of unit diffused resistors of the same shape and of a second conductivity type opposite to the first conductivity type are arranged in parallel at equal intervals by thermal diffusion or ion implantation. Form. After performing well-known semiconductor process steps such as forming an insulating film and forming contact holes, for example, Al, Aj! A conductive member made of -3i or the like is formed, and a resistor is simultaneously formed by connecting the plurality of unit diffused resistors in series or in parallel via the conductive member.

In this way, the plurality of unit diffused resistors constituting the resistor are formed in the same process, and the conductive members that electrically connect the unit diffused resistors constituting each resistor are also the same in all resistors. Formed during the process.

Therefore, the temperature coefficients of the plurality of resistors become almost uniform, and the temperature tracking characteristic of the resistance value ratio between the resistors becomes very good.

Further, since the unit diffused resistors are formed by a semiconductor process, the resistance value of each unit diffused resistor can be formed with very high precision, and the resistance value deviation of each unit diffused resistor can be made very small. Therefore, it is possible to create a large number of resistance networks on the same wafer, in which the resistance value ratio between the plurality of resistors is very accurate and the temperature tracking characteristics are very excellent.

〔Example〕

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

FIG. 1 is a schematic plan view showing one embodiment of the present invention.

In the figure, the unit diffused resistor 2.2° is a p-type diffused resistor having a predetermined resistance value, and is formed by adding and diffusing impurities into an n-type semiconductor substrate by thermal diffusion or ion implantation. be done. The above unit diffused resistance 2.2゛ is
A plurality of them are alternately arranged in parallel at equal intervals of a predetermined length d.

Further, every other unit diffused resistor 2 is connected to A1, Aj! through a contact hole 3 for wiring. They are connected by a conductive member 4 made of -3i or the like.

That is, an arbitrary number n of unit diffused resistors 2 are connected in series via contact holes 3 and conductive members 4.

On the other hand, an arbitrary number n of unit diffused resistors 2' arranged between the unit diffused resistors 2 and 2 have a koshi tact hole of 3°.
3' and /l provided at both ends of each unit diffused resistor 2''
, A1-3i, etc. are connected in parallel via a conductive member 4'.

Furthermore, the unit diffused resistor 2.2 connected in series,
Unit diffused resistors 2 (2
-1) and 2 (2-n) are connected to external connection electrodes 6.6 made of A1, A1-3i, etc. through electrode contact holes 5.5.

In addition, the above unit diffused resistors 2"2" connected in parallel
The unit diffused resistor 2' at the left end in the figure...
Both ends of (2-n) have electrode contact holes 5゜.
5' to an electrode 6'6' for external connection.

In the above configuration, for example, let the resistance value of the unit diffused resistor 2 and the unit diffused resistor 2' be X [Ω], and the unit diffused resistor 2.2
, ... and unit diffused resistors 2'2'... are arranged, n unit diffused resistors 2 (2-1), 2 (2-2), ... connected in series ...2 (2
-n) (expressed as series resistor R for convenience) is nx (Ω), and n unit diffused resistors 2° (2°-1), 2' (2 '-2)・
The total resistance value of 2'(2'-n) (expressed as parallel resistor R2 for convenience) is X/n (Ω).

Therefore, the resistance value ratio R+/Rz of the series resistor R1 and the parallel resistor R2 is as follows.

As a result, by setting the number n of unit diffused resistors 2 connected in series and unit diffused resistors 2 connected in parallel to an arbitrary number, it is possible to obtain a pair of resistors having an arbitrary resistance value ratio n2. becomes.

Moreover, since the unit diffused resistors 2.2'' serving as unit resistors are formed in the same process on the semiconductor substrate, the resistance value of each unit diffusion becomes substantially uniform, and the temperature coefficient also becomes substantially uniform.

Therefore, it is possible to obtain a pair of resistor chips having a highly accurate resistance value ratio.

Furthermore, in this embodiment, since the unit diffused resistors 2 connected in series and the unit diffused resistors 2'' connected in parallel are arranged alternately, the arrangement position of each unit diffused resistor is changed in the lithography process etc. Variations in resistance value and temperature coefficient due to variations in line width of each unit diffused resistor 2.2' caused by differences between series resistor R1 and parallel resistor R2
This results in a paired resistor chip with a very precise resistance value ratio and very good temperature tracking characteristics.

Furthermore, since the unit diffused resistor 2.2' is formed by a semiconductor process, it is easy to miniaturize the unit diffused resistor 2.2' by a normal semiconductor process, and it is possible to create a very small paired resistor chip. I can do it. Furthermore, since a large number of paired resistor chips can be manufactured on the same wafer, it is possible to reduce the cost by mass production.

In the above embodiment, an n-type Si substrate is used as the semiconductor substrate, and a p-type unit diffused resistor is formed in the n-type Si substrate, but the present invention is not limited to the above embodiment. Instead, a resistor network may be formed by forming an n-type extended NT resistor on an n-type Si substrate, and the semiconductor substrate is not limited to a Si substrate, but may be made of germanium (Ge) or the like. It is also possible to use other semiconductor substrates. Further, both the first resistor and the second resistor may be formed by connecting unit diffused resistors in series or in parallel.

Furthermore, the present invention is not limited to a pair of resistors as in the above embodiments, but also includes a plurality of three or more resistors formed by connecting a plurality of unit diffused resistors in series or parallel in every other column. It can also be easily applied to resistor networks that can be used in bridge circuits, filters, etc.

〔Effect of the invention〕

According to the present invention, a plurality of unit diffused resistors of the same shape formed in the same process and arranged in parallel at equal intervals in a semiconductor substrate,
Furthermore, since it has a plurality of resistors formed by connecting these unit diffused resistors in series or parallel via a plurality of conductive members formed in the same process, each resistor can be formed in the same process. As a result, it is possible to obtain a resistor network having a pair of resistors with high accuracy and an extremely excellent temperature tracking characteristic and a resistance value ratio, and a plurality of resistors with extremely uniform temperature dependence of the resistance value.

In addition, since a large number of the above-mentioned resistor network chips can be manufactured on the same wafer using a semiconductor process, it is possible to produce a large number of resistor network chips with extremely high throughput, and the mass production effect can significantly reduce manufacturing costs. Become.

Furthermore, if a plurality of unit diffused resistors are connected in series or parallel every other column via a conductive member to form a plurality of resistors as described in claim 2, the resistance of each resistor is It is possible to obtain a resistor network whose values are more accurate, the temperature dependence of the resistance value of each resistor is very uniform, and whose temperature tracking properties are better.

[Brief explanation of drawings]

FIG. 1 is a schematic plan view illustrating an embodiment of a resistor network according to the present invention. 2.2°...Unit diffused resistance, 3.3゛...Wiring contact hole 4.4" ・
...Conductive member, 5.5゛...Contact hole for electrode, 6...Electrode. Patent applicant: Toyota Industries Corporation I

Claims (1)

[Claims] 1) In a resistance network formed by forming a plurality of resistors on the same substrate, a semiconductor substrate of a first conductivity type, and the same process line arranged in parallel at equal intervals within the semiconductor substrate. A plurality of unit diffused resistors having the same shape and having a second conductivity type opposite to the first conductivity type formed by the above, and a part of the plurality of unit diffused resistors are connected in series or in parallel via a conductive member. A resistance network characterized by having a plurality of resistors connected to. 2) The resistor network according to claim 1, wherein each of the plurality of resistors is formed by connecting the plurality of unit diffused resistors in series or parallel via the conductive member every other column. .