JPS58166757A - Formation of resistor - Google Patents

Abstract

PURPOSE:To prevent the generation of dispersion in the resistance value of the resistor to be formed even when discrepancy of positioning of a mask is generated by a method wherein between the high resistivity regions, the low resistivity region having width narrower than width of the regions thereof by the value in which discrepancy of mask positioning is estimated is formed. CONSTITUTION:A P<+> type diffusion treatment is performed to an N type epitaxial layer 2 on a substrate 1 through the mask 4 to form the regions 3, 3 to be the large resistivity regions. The mask 4 is removed by etching, and the mask 5 is applied thereon. The mask 5 thereof is narrower than width of the mask 4 by the previously decided value. The value thereof is so selected as to be larger than the value expected to be generated by positioning of the masks 4, 5. A diffusion treatment is performed through the mask thereof to make the region 6 to have smaller resistivity than the regions 3, 3, and moreover to be formed in the conductive type the same with the regions 3, 3, and the second impurity diffusion region is formed. The regions 3, 6, 3 are connected electrically, and the resistor 7 having the resistance value to be decided according to resistivities and geometrical sizes thereof is formed.

Description

Detailed Description of the Invention (110 Invention 0 Technical field) The present invention provides a method for forming a resistivity by educating the arrangement and structure of resistive regions when forming a resistor consisting of resistive regions having different resistivities on a semiconductor substrate. Regarding.

(2)0 Background of the Invention Conventionally, when forming a resistor on a semiconductor substrate, two types of resistors with different specific resistances are considered based on ease of fabrication, ease of adjustment, and keeping the length of the resistor within a predetermined length. A method is used to form a desired resistance tube by combining one or more resistance regions. These resistance regions are formed identically,
Since a mask is used to form the resistance region, the actual situation is that the alignment does not necessarily match, and it is impossible to avoid variations in resistance value.

(3) In the conventional technology and the gap point, that is, in the conventional resistor VC formation method, each resistor region is formed with the same width regardless of the presence or absence of a difference in specific resistance, while the resistor mask alignment At present, it is not possible to achieve sufficient matching, so the above-mentioned resistance regions are formed in a shifted position as shown in the first IIK. In the 111th, ai
b represents the first C-type impurity diffusion region, C represents the second r-type impurity mineralization region, and W represents the amount of deviation. d.

・is a contact liaison. FIG. 2 is a sectional view taken along the line O1-N in FIG. 1, and the same parts are given the same reference characters. f is a semiconductor substrate, g is an N-type epitaxial layer, h
is an insulating film, and t is an aluminum electrode.

If the mask misalignment as described above occurs, it is impossible to avoid variations in the resistance values of the formed resistors. Therefore, the result is that the resistance value tm of the resistor cannot be set accurately.However, in parts where such precision is required, the excellent A of the above-mentioned O resistor formation method can be utilized, depending on the method. It becomes impossible to form that resistance.

(4) 0 Purpose of the Invention The present invention was devised in view of the drawback #C of the conventional resistor forming method as described above, and its purpose is to eliminate variations in the resistance value of the resistor formed even if mask displacement occurs. The object of the present invention is to provide a method for forming a resistance that does not cause the occurrence of resistance.

(5) Structure of the Invention The purpose of this invention is to provide a first resistance region of an opposite conductivity type at both ends of a resistor to be formed on a semiconductor substrate of one conductivity type, and an opposite conductivity region interposed between these first resistance regions. When forming a resistor having a 20th resistance region of the shape, the width of the first resistance region is the width of the second resistance region) 11I! Form widely,
This is achieved by forming the second resistance region as a second impurity diffusion region that has a smaller resistivity than the first impurity diffusion region and overlaps both ends of the first impurity diffusion region.

(6) First Embodiment The present invention will be described in detail below with reference to the accompanying drawings.

First, as shown in FIG. 3, a KN-shaped pitaxial layer 2 is formed on the semiconductor substrate I [1].

Next, on this substrate 1ON formed pitaxial layer 2, a fourth layer is applied.
As shown in the figure, a mask 4 for forming the first impurity diffusion region 3.3t-diffusion having a high specific resistance is applied, and P information is applied to make the region 3.3 a region with a high specific resistance through this mask. Apply diffusion treatment to

Then, the mask 4 is etched and removed, and a mask 5 is applied thereon as shown in FIG. As shown in FIG. 7, this mask 5 is narrower than the width of one mask 4 by a predetermined value. This value is chosen to be larger than the amount of misregistration that would occur in the alignment of mask 4.5. Through this mask, a region 6 surrounded by a dotted line in FIG. 5 is diffused to have a lower specific resistance than the region 3.3 and the same conductivity type as the regions 3, 3, thereby forming a second impurity diffusion region. Therefore, both ends of the second impurity diffusion region 6 are connected to the first impurity diffusion region 3.3.
It overlaps one end of the . These territories [3, 6, 3t'
i is electrically coupled and can be a resistor 7 with a resistance value determined by their resistivity and geometrical dimensions.

After this process is completed, the mask 5 is etched away, and as shown in FIG. 9 is coated on said area 3.6.3 forming an aluminum electrode 10 in its contact window 8. This aluminum electrode 10 has a region 3 with high specific resistance and low tn resistance.
．． A smooth contact tube can be created between the two.

The resistor 7 between the electrodes 9 and 9 is connected to and incorporated into a predetermined circuit out of various functional circuits formed on the semiconductor substrate l.

In the resistor formed by the method of the present invention, the width of the first impurity diffusion regions 3, 3 is made wider than the width of the 20th impurity diffusion region 6, so even if a misalignment of the mask occurs, There is no possibility that the resistance value of the resistor 7 will vary. Therefore, a highly accurate resistor can be formed. This effect can be obtained without losing the advantages obtained when resistors are made from impurity regions having different specific resistances, that is, ease of production and ease of adjustment *1. Furthermore, since the region 3.3 is formed to have a low resistance, the electrical connectivity with the aluminum electrode IO is improved.

In the above example, the high resistivity region 3.3 and the low resistivity region 6
Although they are formed first, they may be formed in the opposite direction.

(7) 0 Effects of the Invention In other words, the multi-layered resistor of the present invention forms high resistivity regions at both ends, and the width of the high resistivity region is the same as that between these high resistivity regions. Since a low resistivity region is formed with a width that is narrow enough to account for misalignment of the mask, even if misalignment of the mask occurs when forming the resistor,
However, it does not cause variations in resistance. This effect comes without losing the advantages obtained when creating resistors using different resistivities. Moreover, at the same time as the above effect, the contact column with the electrode can be improved.

[Brief explanation of the drawing]

Figures 1 and 2 are a plan view and a vertical cross-sectional view of a resistor formed by a conventional method, Figures 3 to 6 are diagrams showing each step of the present invention, and Figure 7 is a diagram showing the steps of the present invention. The geometric size of each mask, and therefore each region of the resistor formed
It is a diagram illustrating the size. In the figure, 1 is a semiconductor substrate, 3.3 is a first impurity diffusion region, and 6 is a second impurity diffusion region. Patent applicant Fujitsu Ltd. Figure 1 Figure 2 Figure 3 Figure 4 Figure 5

Claims (1)

[Claims] Both ends IS of a resistor to be formed on a semiconductor substrate of one conductivity type
When forming a resistor having a second resistance region of the opposite conductivity type interposed between the resistance region of the K-opposite conductive foil 1 and the resistance region of the iron ore 1, the first resistance region is replaced with the second resistance region of the iron ore 1. The second resistance region is formed wider than the first resistance region.
A method for forming a resistor, characterized in that the impurity diffusion region is formed as a second impurity diffusion region having a small resistivity and overlapping both ends of the first impurity diffusion region.