JP2003234405A - Layout pattern of high precision resistivity - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pattern layout for a semiconductor IC, which is able to improve the specific precision of a resistive element. <P>SOLUTION: Electric potential of a substrate on which the resistive elements of a voltage divider circuit requiring high specific precision are arranged, is pluralized so as to reduce electric potential difference between resistors located on the substrate and the substrate. Thus unevenness of resistance values between individual resistive elements caused by the electric potential difference between the resistive elements and the substrate, can be reduced, which in turn enables production of a voltage divider circuit having high specific precision. <P>COPYRIGHT: (C)2003,JPO

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a layout pattern for improving the ratio accuracy between a plurality of P resistors in a semiconductor IC. 2. Description of the Related Art A P-resistor is used in a semiconductor IC, and a resistance of a voltage-dividing circuit for generating a voltage obtained by dividing a voltage applied to both ends of the P-resistor according to a ratio of resistance values of the P-resistors. FIG. 4 shows a layout pattern diagram. P resistance element 40
1, 402, 403, 404, 405, and 406 are connected in series. Both ends of the total resistance are connected to terminals 408 and 410, and the midpoint between the resistance elements 404 and 405 is connected to terminal 409. FIG. 6 is a sectional view of FIG. P resistance elements 601, 602, 603, 604, 605, 606
Are connected in series. Both ends of the total resistance are terminals 608 and 61
0, and the midpoint between the resistance elements 604 and 605 is the terminal 6
09. FIG. 5 shows a conventional circuit diagram corresponding to the layout pattern diagram. This is a voltage divider circuit in which the voltage applied to the 508 and 510 terminals is determined by the ratio of the resistance between the 509 and 508 terminals and the resistance between the 509 and 510 terminals. . [0005] In a semiconductor IC, P
When a resistor is used, in order to arbitrarily set the resistance value of the P resistor, an impurity having an appropriate concentration is added so that the resistance value of polysilicon used as the resistor becomes the set resistance value. Therefore, when a potential difference occurs between the substrate on which the P resistance is disposed and the P resistance, electrons move within the P resistance, and the impurity concentration of the P resistance apparently changes. Therefore, when a potential difference occurs between the P resistance and the substrate, the resistance value of the P resistance changes due to the potential difference. Usually, the highest potential or the lowest potential used in the IC is used as the base potential of the semiconductor IC, so the P resistor of the voltage divider used within that voltage is connected to the higher voltage side The difference between the resistance value of the P resistance and the resistance value of the P resistance connected to the lower voltage side is different. Therefore, when a voltage dividing circuit using P resistors arranged on the same substrate is used, a deviation occurs between the P resistor having a larger potential difference from the substrate and the P resistor having a lower potential difference. . This means that even if each resistor element is exactly the same size and is located adjacent
There is a problem that the resistance value of each resistance element changes due to the potential difference from the substrate, and high specific accuracy cannot be realized. In order to solve the above problems, a substrate on which a P resistor is arranged is separated by a well, and the potential of the separated well is set to the potential of the P resistor arranged on the well. By making it common with the potential, the potential difference between the P resistor and the board is reduced, and the resistance value generated by the potential difference between the P resistor connected to the higher voltage side and the board of the P resistor connected to the lower voltage side Are made substantially the same, and the ratio accuracy between the resistance elements is improved. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS By using a voltage dividing circuit configured as described above, a base on which a P resistor is arranged is separated by a well, and the potential of the separated well is set on the well. The potential difference between the P resistor and the board is reduced by making it common with the potential of the P resistor to be placed, and it is connected to the higher voltage side
Since the amount of deviation of the resistance value caused by the potential difference between the P resistance and the base of the P resistance connected to the lower side of the voltage is substantially the same, it is possible to improve the relative accuracy between the respective resistance elements. An embodiment of the present invention will be described below with reference to FIG. FIG. 1 is a pattern layout diagram of a resistor section of a voltage dividing circuit including the present invention. First, FIG. 1 shows a layout pattern diagram of the voltage dividing circuit. P resistance elements 101, 102, 103, 104, 105, and 106 are connected in series. Both ends of the total resistance are terminals 110 and 112
And the middle point between the resistance elements 104 and 105 is the terminal 11
Connected to 1. At this time, connection is made so that the potential of the substrate on which the resistors are arranged is the potential of the middle point of each resistor. The bases connected to the midpoints of the resistors are 107, 108, and 109. Next, FIG. 3 shows a sectional view of FIG. P resistance elements 301, 302, 303, 304, 305, 306
Are connected in series. Both ends of the total resistance are terminals 310 and 31
2 and the middle point between the resistance elements 304 and 305 is the terminal 3
11 is connected. The midpoint of each resistor is connected to each of the bases 307, 308, 309. FIG. 2 shows a circuit diagram corresponding to the layout pattern diagram. This is because the voltage applied to the terminals 210 and 212 is determined by the ratio of the resistance between the terminals 211 and 210 to the resistance between the terminals 211 and 212.
This is a voltage dividing circuit for determining the voltage of the 11 terminals. Using the voltage dividing circuit constructed as described above,
The substrate on which the resistor is placed is separated by a well, and the potential of the separated well is made common to the potential of the P resistor placed on the well, thereby reducing the potential difference between the P resistor and the substrate, Since the amount of deviation of the resistance value caused by the potential difference between the P resistance connected to the high side and the base of the P resistance connected to the low side is almost the same, it is possible to improve the accuracy of the resistance ratio It becomes. As described above, according to the present invention, the base on which the P resistance is disposed is separated by a well, and the potential of the separated well is made equal to the potential of the P resistance disposed on the well. By making them common, the potential difference between the P resistance and the substrate is reduced, and the deviation in the resistance value caused by the potential difference between the P resistance connected to the higher voltage side and the P resistance substrate connected to the lower voltage side. This has the effect of making the amounts the same and improving the accuracy of the resistance value ratio.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a layout pattern of a resistance element according to the present invention. FIG. 2 is a circuit diagram using a resistance element. FIG. 3 is a layout sectional view using a resistance element. FIG. 4 is a layout pattern of a conventional resistance element. FIG. 5 is a circuit diagram using a conventional resistance element. FIG. 6 is a layout cross-sectional view using a conventional resistance element. DESCRIPTION OF SYMBOLS 101, 102, 103, 104, 105, 106 Resistive element patterns 107, 108, 109 Electrically separated bases 110, 112 on which resistive elements are arranged Voltage input terminals 111 Voltage output terminals 201, 202, 203, 204, 205, 206 Resistance elements 207, 208, 209 Electrically separated bases 210, 212 on which resistance elements are arranged Voltage input terminal 211 Voltage output terminals 301, 302, 303, 304, 305, 306 Resistance element pattern 307, 308, 309 Electrically separated bases 310, 312 on which resistive elements are arranged Voltage input terminals 311 Voltage output terminals 401, 402, 403, 404, 405, 406 Resistive element patterns 407 Bases 408 on which resistive elements are arranged 410 Voltage input terminal 409 Voltage output terminal 501, 5 2, 503, 504, 505, 506 Resistance element 507 Base 508, 510 on which resistance element is disposed Voltage input terminal 509 Voltage output terminal 601, 602, 603, 604, 605, 606 Resistance element pattern 607 Base 608 on which resistance element is disposed , 610 voltage input terminal 609 voltage output terminal

Claims (1)

Claims: 1. A polysilicon resistor element for a semiconductor integrated circuit.
An IC layout pattern, wherein a potential of a substrate on which the P resistance is placed is divided to reduce a potential difference between the P resistance and the substrate in a layout pattern (hereinafter referred to as a P resistance).