JPS5867058A - Semiconductor device - Google Patents

Abstract

PURPOSE:To take the relative ratio of ion injection resistors with high accuracy regardless of shape by setting the number of the ion injection resistors while being conformed to a resistance ratio without resembling the shape in the relative ratio of the ion injection resistors. CONSTITUTION:A high-concentration region 49 is formed at one position of the ion injection resistor region 23' of the resistor R1 while being crossed on the resistor region 23', and the full length (L1'+L2'+L3') of the resistor sections of the resistor R2 and the full length (L4'+L5'+L6') of those of the resistor R1 are equally designed. The number of the substantial ion injection resistor sections between the resistors R1 and R2 is uniform because the high-concentration region 49 is overlapped on the resistor region 23'.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention particularly relates to ion implantation resistors in semiconductor integrated circuits.

In recent years, semiconductor integrated circuits have undergone significant changes as they become more highly integrated.

Due to problems such as cage thermal resistance, circuit currents are becoming smaller and smaller. One of the conditions required when designing to reduce circuit current is to increase the value of the resistor used in the circuit. Although various structures have been proposed for resistors having relatively large resistance values, ion-implanted resistors have recently been frequently used as this type of resistor.

Conventionally, when it is necessary to accurately measure the relative ratio of resistance values between ion-implanted resistors, there are restrictions on the shape of these resistors.
It is made in the shape shown in Fig. 1 or 2. In other words, as shown in Fig. 1, the number of corners of the resistance regions 30 and the length of the resistance regions 3 are made the same in the resistance R1% R1, or the resistor 81 and the shape of the bird are made exactly the same as shown in Fig. 2. It was either. In addition, in figure @1, 3
．． 6 is a low concentration resistance region formed by ion implantation of acceptor impurities if the part where the resistance is to be formed is N type, 2.5 is a contact window for aluminum wiring, and 1.4 is ion implantation. This is a high-intensity boron diffusion region for making contact between region 3.6 and the aluminum ζ wiring. In addition, the region 1.4F1 example ILF1NPN) is formed at the same time as the base of the transistor.

Enzan has the same number of corners of the resistance (R6) that improves the relative ratio.Due to variations in the ion-implanted region 3.60 layer resistance (hereinafter referred to as R8), the resistance of the corners is This is because there will be a big gap.

In other words, if this variation in resistance at some corners causes a difference in the number of corners between resistors that take relative ratios, it will cause a discrepancy in the relative ratio, so resistors that take relative ratios must have the same number of corners. Must be.

In Figure 2, 8 and 12 are low concentration resistance regions into which acceptor impurities are ion-implanted, 9.13 is a contact window for M wiring, and 7.11 is for making contact between ion implantation region 8.12 and M wiring. P-type impurity region, and 10.
14 is a high concentration boron diffusion region connecting multiple ion implantation regions, and this region 10.14 and region 7.11 are N
PN) formed at the same time as the base of the transistor. In particular, the resistance ratio 1 shown in FIG. 2 is a resistance shape used when the M wiring for circuit connection and the ion-implanted resistors (R1, R1) must intersect in terms of layout. That is, due to the structure, there is a large step in the oxide film above the ion-implanted resistor, and this may cause a break in the M wiring. This is because the ion implantation resistor process is performed last to eliminate changes in resistance, so the 8i0fJ of the surface up to that point is
[This is because the wall is getting thicker.] Therefore, the low concentration regions are connected by the high concentration regions 10 and 14, and the AJ wiring is provided on the high concentration regions 10 and 14. In this case, the relative ratio of the resistors is taken as a similar figure, and the difference in resistance value due to the base lateral spread 9 after diffusion is canceled out to take the relative ratio.

As described above, the conventional ion-implanted resistor for improving the relative ratio cannot be formed into a free resistor shape, which poses a problem in mask layout.

Hereinafter, such conventional problems will be explained in more detail using two resistors with different resistance shapes as an example.

First, the resistance value R of the ion-implanted resistor of the normal shape shown in Figure 3 is the width of the resistance region 180 on the mask pattern W.
1 length is L, the following equation (1) is given by taking into consideration the lateral spread of impurity diffusion in the resistance region 18 and the high concentration region 17 for making contact with the M wiring.

In equation (1), R8 is the resistance of the ion-implanted resistance region 180 layer, ΔL1ΔW is the deviation from the designed length L and fiW of the resistance range 18 caused by the lateral diffusion of impurities, and α is the AI wiring This is the resistance at the contact portion with the high concentration region 17 and the high concentration region 17. In this case, this α can be ignored with respect to the resistance value of the ion-implanted resistance region 18, so it is generally deleted. Further, in FIG. 3, 16 is an epitaxial layer in which a resistor is formed, for example in an integrated circuit, and 15 is a separation layer for electrically insulating from other circuit elements.

Now, two resistors 1' that need to have a good relative ratio? ,
, , R, are formed as shown in Fig. 4, the relative ratio of resistance between these resistors R, , R, Kl/R% is determined by equation (1), and the resistance value of each is determined by equation (2). become that way.

7L-3・ΔL =......(2) Here, the resistance R1% shown in Figure @4 is formed in the same way as the resistance shown in Figure 2. In other words, the resistance - is a resistance region 21 with a design value length of L1%Ll and .
are connected in series with a high concentration 819, and high concentration Wk2o of a contact portion is formed at both ends to form a wiring portion. The resistor R2 is constructed by connecting resistance regions 23 having lengths L4 and L in series with a high concentration layer 22, and forming a contact portion of a high concentration layer 24 at both ends to serve as a wiring portion. For convenience, the relative ratio is set to 1. That is, the length of the total resistance area 21 of the resistor R2, +L, +L, ) and the length of the total resistance area 23 of the resistor R1, L4 + Ll), are L, and the width of the resistance area 21.23 is W, W/ are designed identically. In addition, changes due to lateral inward spreading diffusion ΔL1, Δ
−1ΔL1%ΔL4 and ΔL are the same.

(As you can see from the door type, even if the resistance length is designed to be the same in order to take the relative ratio accurately, the relative ratio will not be 1, but 3・Δ
The error is L, 2·ΔL. This is because the entire resistance region 21 is connected by two high concentration regions 19, whereas the resistance region 23 is connected by one high concentration region 22. This is because diffusion causes an error in the resistance length L. Tsumashi,
With such a shape, accurate relative ratios cannot be obtained.

From equation (2), the relative ratio R between two resistance persons and 8
The general formula for A/RB is derived as formula (3).

Here, n and n' are the number of ion implanted parts whose ends are the planes where the ion implanted part and the high concentration region intersect, which corresponds to the number of ion implanted resistors. Also, β is the resistance length of the resistance person and resistance B
It is the proportionality constant of resistance *L.

Hereinafter, this will be referred to as the resistance proportionality constant. Equation (3) shows that the relative ratio of ion-implanted resistors differs when the number of ion-implanted resistors that make up the resistance differs.

From the above, the relative ratio of the ion implantation resistances is good in the resistance shape when the number of ion implantation resistors 26 and 29 are equal and the resistance proportionality constant β is 1 as shown in Figure 5.

This is because the relative ratio shift due to the lateral spread 9 of the high concentration region 25.28 is as shown in equation (4) rather than equation (3). It is assumed that the width of the ion implantation resistors 26 and 29 is large.

In the past, accurately determining the relative ratio between ion-implanted resistors was possible only when the two resistors were similar in shape, as shown in FIG. This has made it difficult to reduce the size of the pellets on the mask layout, posing a major obstacle.

The present invention eliminates these drawbacks, and its purpose is to provide an ion-implanted resistor that can freely set the shape of the ion-implanted resistor that is relatively northward on the mask layout, and that can also accurately change the relative ratio of the resistors. The purpose of the present invention is to provide semiconductor devices.

The basic principle of the present invention can be explained by assuming a vector whose "magnitude" is the voltage drop due to the conventional technology and the opposition, as shown in the drawing.
In conventional technology, the resistance that takes the relative ratio is the "magnitude" of the vector.
Whereas the "number" and "order of direction" were matched, in this application, the resistance that takes the relative ratio is the "number" of the vector as shown in Figure 7.
In this method, the number of ion-implanted resistors is roughly matched to the resistance ratio and the relative ratio is calculated, regardless of the directional order.

Next, one embodiment of the present invention is shown in FIG. 8 and will be described in detail. The resistor shown in FIG. 8 is an application of the present invention to the resistor shown in FIG. 4, and in this case, the relative ratio l is intended. For this purpose, the ion-implanted resistance region 2 of the resistor R3 is
A high concentration region 49 is formed at one place in 3' across the resistance region 23', and the entire length of the resistance part of the resistance bird (Ll'
+L,'+L, the total length of the ridge and that of resistor R1 (L,'+
It is designed the same as L, '+ L, and one. As shown in FIG. 8, by overlapping the high-concentration region 49 with the resistance region 23', the number of substantial ion-implanted resistance parts between the resistances R, , R, is the same, and therefore, according to equation (3), in this case The relative ratio of is (5)
The formula becomes The same applies during resistance.

7-L-3ΔL-r; ■=” (5) Equation (5) shows that the relative ratio can be determined with high accuracy regardless of the lateral spread of diffusion.

FIG. 9 shows a second embodiment of the invention. This is because, due to the mask layout, the resistor R8 must have a vertically elongated shape with one resistor region 53 as shown in the figure, and the resistor R is formed by connecting three resistor regions 55 with a high concentration layer 56. In this model, the ratio of the resistance length of the resistor R7 and the resistance length of the resistor R8 on the mask is set to R8/R7=2, aiming at the relative ratio R'y=1 of these. For this purpose, high concentration layers 52 are formed at five locations in the resistor R, overlapping with the resistor R. In this case, the relative ratio is according to equation (3) β = 2, rl = 6, n = 3
Therefore, R82L-6ΔL TcT(T: ■τ= 2...e(6).
6) It can be seen that the relative ratio of resistors R7 and R8 can be determined with high accuracy according to formula.

Furthermore, the present invention is applicable even when the relative ratio of resistances is not an integral multiple. For example, a resistance Ra of lOKΩ and a resistance R of 36Ω
Consider the case where the relative ratio t of the ion implantation resistance of B is taken. At this time, if the ion implantation resistance number of the resistor Rm is 2, the ion implantation resistance number of the resistor RB is 11' = 3.6X 2
= 7.2, which should be approximately 7 lines. Therefore, equation (3) is obtained. In this way, if the number of ion-implanted resistors is approximately equal to the ratio of the resistance values, the accuracy will be the best.

The case where this relative ratio of resistances is not an integral multiple will be explained in detail with reference to another example. Figure 1θ is an example of this, RIO:R9
Suppose that a relative ratio of =-1:1.75 is required.

In this case, in order to make the needle installation easier by using the number of ion implanted resistors as the number of vessels, take the least common multiple of them.

:R,=4:? shall be. Its shape is, for example, as shown in FIG. 10, where the resistor R8° has two resistance regions 60 and is divided into two by a high concentration region 61. Resistor R9 has three resistance regions 63, two of which
1 is formed so as to be divided into three by two high concentration regions 62. Therefore, the relative ratio of these is given by equation (3): β=-7-1
rt' = 7. This is because n=4, and it can be understood from equation (7) that even when the relative ratio of the resistances is not an integral multiple, the relative ratio can be determined with good accuracy.

The embodiment of the present invention shown in FIG. 11 is obtained when the relative ratio of the resistances is an integer multiple and the ion-implanted resistors of the main resistor are connected in parallel, and the relative ratio is calculated using the present invention. , R1
1 is constructed by connecting two ion-implanted resistors 69 in parallel with a height of 1 [m67.68]. R11 is one resistance region 6
It is formed by 6.

These resistance regions 66, 69 have the same shape. Therefore,
As shown in equation (1), the relative ratio R12/R11=2, and the relative ratio can be obtained with high accuracy.

In the embodiment shown in FIG. 12, the relative ratio of the resistances is not an integral multiple, but the ion-implanted resistors of the main resistors are connected in parallel and the relative ratio is determined using the present invention. In other words, as in the embodiment shown in Figure 1O, the resistance is set to a common multiple of resistance and the relative ratio is calculated.
In the example, R1,: R,4 == 1:1.75 to R13:
It is sufficient to set R14=4 near and connect ion-implanted resistors in parallel in inverse proportion to the resistance ratio. That is, R13
When R14 connects seven ion-implanted resistors 75 in parallel, and R14 connects four regions 72 in parallel with high concentration layers 70 and 73, the result is as follows.

In the embodiment shown in FIG. 13, the relative ratio of resistance is ! One of the resistors R4 is connected in series with three ion-implanted resistors 81 by two high concentration layers 80, and the other resistor R4 is connected in series with high concentration J@
This is an example in which relative ratios are taken as series and parallel connections of resistance regions 78 according to '77. From formula (1), horse 8, 几 1. can be obtained as 3L-3ΔL R+, .

In the embodiment shown in FIG. 14, the relative ratio of the resistances is not an integral multiple, and R17:R18=1.5:1.25.

In this example, the resistors that take the relative ratio are connected in series and parallel W.
The relative combination ratio is taken as a series.

As described above, by using the present application, the relative ratio of ion implanted resistors can be determined with high accuracy by setting the number of ion implanted sheets according to the resistance ratio, without making their shapes similar. In the above, an N-type epitaxial layer is formed on a P-type substrate, and the ion implantation resistance region is made of P-type, for example, a low concentration of boron. Formed by implantation, high concentration region is boron diffusion, it is 4NP
N) Although the transistor space region diffusion is formed at the same time, a P-type epitaxial layer may be formed on an N-type substrate and N-type impurities may be used.

[Brief explanation of the drawing]

Figures 1 and 2 are plan views showing two resistors made by the prior art that require accurate relative ratios, Figure 3 is a plan view of a general resistor, and Figure 94 is a plan view of two resistors made by the prior art. Fig. 5 is a plan view showing two resistors having an accurate relative ratio according to the prior art, and Fig. 6 is a plan view showing the basic idea for obtaining an accurate relative ratio using the prior art. No. 71 is a plan view of two resistors showing the basic idea of the present invention, and Figs. 8 to 114 are plan views of two resistors showing embodiments of the present invention, respectively. 1.4.7.10.11.14.17.19.20.2
2.24.25.27.28.30119.20.22
．． 24.49.52.56.61.62.67.68.
70.73.77.80...P-type high concentration layer, 2
．． 5.9.13・・・Contact window, 3.6.8
．． 12.18.21, 23.26.29.53.55.
60.63.66.72.75.78.81...
・P low concentration ion implantation resistance region. #l Figure number 2 [ 8 Grass 3 Figure A' 2 /z7 4th "41?3 Rtθ R9 6ri/;'/2
2//Kai l1 Country number 12 Figure 78 R/6 Sheep 13 1? /, 3 θO 15 Memu 14 Fig.

Claims (1)

[Claims] A semiconductor resistor region of one conductivity type, and a semiconductor region formed overlappingly with the resistor region, which is the same conductivity type as the resistor region and which also has a high impurity concentration, such as dividing the resistor region into a plurality of parts. A semiconductor device comprising a resistance element including: