JP2008244406A - Semiconductor device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the following problem: a resistor element does not work in accordance with design with respect to a high-frequency signal. <P>SOLUTION: A semiconductor device includes a substrate, a well formed on the substrate and having a relatively low impurity concentration, an insulating film formed on the well, and a resistor element engineered for a high-frequency signal and formed on the insulating film. For one part of the resistor element and the other part, the semiconductor device further includes a first parasitic capacitance to be formed between one part of the resistor element and the insulating film, a second parasitic capacitance to be formed between the other part of the resistor element and the insulating film, and a parasitic resistance to be formed between the first and second parasitic capacitances in the well. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a semiconductor device for high frequency signals (for example, for signals of several GHz) having a resistance element.

  In the conventional semiconductor device SD10 shown in FIG. 3, the problem to be solved “reduction of parasitic capacitance in a high-frequency region” described in Patent Document 1 below, and the main elements described in Patent Document 2 below. In connection with the “configuration of the shield layer between the inductance and the element isolation region for reducing the substrate resistance”, the circuit configuration is such that the impurity concentration is “relatively high” on the P-type substrate S1. A type well W10 is formed, an insulating film D2 having a function of an element isolation film is formed on the P type well W10, and a resistance element R is formed on the insulating film D2.

  An insulating film D1 having the function of an interlayer insulating film is formed on the resistance element R, and metal wirings M1a and M1b are formed on the insulating film D1, and the resistance element R The metal wirings M1a and M1b are connected by contacts CT1 and CT2, respectively.

  The resistance element R has an electrical function in that the input terminal IP2 and the output terminal OP2 are connected to the ground potential GND by the P-type substrate S2, and from the metal wiring M1a, that is, from the input terminal IP1, the high frequency On the other hand, the high frequency signal Sh is received from the metal wiring M1b, that is, from the output terminal OP1.

  Unlike the above-described essential configuration of the semiconductor device SD10, there are parasitic capacitances C1 and C2 between the resistance element R and the P-type well W10 located between the insulating film D2, and in the P-type well W10. A parasitic resistance Rw that is connected in parallel with the resistance element R exists between the parasitic capacitances C1 and C2. Thereby, as shown in FIG. 3, as a path through which the high-frequency signal Sh can pass, in addition to the original path RT1 including only the resistance element R, a detour including the parasitic capacitance C1, the parasitic resistance Rw, and the parasitic capacitance C2 is performed. There is a simple route RT2.

Japanese Patent Laying-Open No. 2005-26616 JP 2000-22085 A

  However, since the resistance value of the parasitic resistance Rw is determined depending on the impurity concentration of the P-type well W10, when the impurity concentration in the P-type well is high or extremely high, the resistance value of the parasitic resistance Rw is As a result, the high-frequency signal Sh flows preferentially to the detour path RT2 rather than the original path RT1, and as a result, the resistance value of the resistance element R becomes smaller. There is a problem that the element R does not function as designed for the high-frequency signal Sh.

The first semiconductor device according to the present invention is to solve the above-described problems.
A substrate,
A well having a relatively low impurity concentration formed on the substrate;
An insulating film for high-frequency signals formed on the well;
A resistive element formed on the insulating film,
A part of the resistive element and another part of the first parasitic capacitance that can be formed between the part of the resistive element and the insulating film, and between the other part of the resistive element and the insulating film A second parasitic capacitance that can be formed in
And a parasitic resistance that can be formed between the first and second parasitic capacitances in the well.

The second semiconductor device according to the present invention is to solve the above-described problems.
A substrate having a relatively low impurity concentration;
An insulating film formed on the substrate;
A resistance element for a high-frequency signal formed on the insulating film,
A part of the resistive element and another part of the first parasitic capacitance that can be formed between the part of the resistive element and the insulating film, and between the other part of the resistive element and the insulating film A second parasitic capacitance that can be formed in
A semiconductor device further comprising: a parasitic resistance that can be formed between the first and second parasitic capacitors in the substrate.

  According to the first and second semiconductor devices according to the present invention described above, the impurity concentration of the well in the first semiconductor device and the impurity concentration of the substrate in the second semiconductor device are relatively Since the resistance value of the parasitic resistance is increased as compared with the conventional case, the high-frequency signal is a detour composed of the first and second parasitic capacitances and the parasitic resistance having the large resistance value. As a result, the high-frequency signal can flow preferentially to the original path composed of the resistance element, in other words, the resistance element is substantially connected to the high-frequency signal. It becomes possible to function as designed.

  In the above-described first semiconductor device according to the present invention, the substrate and the well are P-type.

  In the above-described second semiconductor device according to the present invention, the substrate is P-type.

Embodiments of a semiconductor device according to the present invention will be described with reference to the drawings.
"Example"

  FIG. 1A is a cross-sectional view illustrating the structure of the semiconductor device of the example. The semiconductor device SD1 of the embodiment is basically a conventional semiconductor device so as to function as a resistance element having a resistance value determined in advance at the design stage with respect to a high-frequency signal Sh (for example, a high-frequency signal of several GHz or more). Similar to SD10 (shown in FIG. 3), a P-type substrate S1, a P-type well W1 (different from a conventional P-type well W10), insulating films D1 and D2, a resistance element R, and (polysilicon P) ), Contacts CT1 and CT, and metal wirings M1a and M1b.

  More specifically, in the semiconductor device SD1, as a circuit configuration, a P-type well W1 having a “relatively low impurity concentration” is formed on a P-type substrate S1, and an element is formed on the P-type well W1. An insulating film D2 having a function of a separation film is formed, and a resistance element R is formed on the insulating film D2.

  The resistor element R is provided with a contact CT1 on the input side of the resistor element R (side receiving the input of the high-frequency signal Sh), and on the other hand, the contact CT2 on the output side (side outputting the high-frequency signal Sh). Is provided. A metal wiring M1a is connected to the contact CT1 as an input-side wiring, and a metal wiring M1b is connected to the contact CT as an output-side wiring. Further, an insulating film D1 having a function of an interlayer insulating film is formed between the resistance element R and the metal wirings M1a and M1b.

  The resistance element R receives an input of the high frequency signal Sh from the metal wiring M1a (that is, from the input terminal IP1) as an electrical function, and on the other hand, transmits the high frequency signal Sh to the metal wiring M1b (that is, the metal wiring M1b). Output to the output terminal OP1). The input terminal IP2 and the output terminal OP2 are connected to the ground potential GND by the P-type substrate S1.

  In spite of being unnecessary for the essential configuration of the semiconductor device SD1 described above, in the semiconductor device SD1, a first parasitic capacitance is formed between the resistor element R and the P-type well W1 located between the insulating film D2. There may be C1 and a second parasitic capacitance C2. Further, a parasitic resistance Rw that can be connected in parallel with the resistance element R may exist between the first parasitic capacitance C1 and the second parasitic capacitance C2 in the P-type well W1. Thereby, as a path through which the high-frequency signal Sh can pass, in addition to the original path R1 including only the resistance element R, the detour including the first parasitic capacitance C1, the parasitic resistance Rw, and the second parasitic capacitance C2. There is a common path RT2.

  As described above, since the impurity concentration of the P-type well W1 is in a “relatively low” state in the semiconductor device SD1, the resistance value of the parasitic resistance Rw is higher than that in the related art, and as a result. The high-frequency signal Sh is suppressed from flowing to the detour route RT2 in preference to the original route RT1. In other words, it is possible to realize that the resistance element R functions as designed for the high-frequency signal Sh.

  In the semiconductor device SD1, in addition to the above-described configuration, as shown in the plan view of FIG. 1B, the resistance element R is separated from the P-type well W1 by a distance d1 (d1 is experimentally determined) in the X-axis direction. It is desirable that the distance is separated by a distance d2 (d2 is a value obtained by experiment etc.) in the Y-axis direction. As a result, the high-frequency signal Sh can flow through the original path RT1 including only the resistance element R, rather than the detour path RT2 including the parasitic resistance Rw in the P-type well W1.

<Modification>
In the semiconductor device SD1 of the above-described embodiment, instead of the semiconductor device SD1 of the embodiment including the P-type substrate S1 and the P-type well W1 whose impurity concentration is “relatively low”, the semiconductor device of the modification illustrated in FIG. Even with the P-type substrate S2 having a “relatively low” impurity concentration in SD2, the same effect as described above can be obtained.

FIG. 6 illustrates a structure of a semiconductor device of an example. FIG. 9 shows a structure of a semiconductor device according to a modification. FIG. 10 shows a structure of a conventional semiconductor device.

Explanation of symbols

  SD1 ... semiconductor device, S1 ... P-type substrate, W1 ... P-type well, D1, D2 ... insulating film, R ... resistance element, CT1, CT2 ... contact, M1a, M1b ... metal wiring, C1 ... first parasitic capacitance, C2: second parasitic capacitance, Rw: parasitic resistance.

Claims (4)

A substrate,
A well having a relatively low impurity concentration formed on the substrate;
An insulating film formed on the well;
A resistance element for a high-frequency signal formed on the insulating film,
A part of the resistive element and another part of the first parasitic capacitance that can be formed between the part of the resistive element and the insulating film, and between the other part of the resistive element and the insulating film A second parasitic capacitance that can be formed in
A semiconductor device further comprising a parasitic resistance that can be formed between the first and second parasitic capacitances in the well. A substrate having a relatively low impurity concentration;
An insulating film formed on the substrate;
A resistance element for a high-frequency signal formed on the insulating film,
A part of the resistive element and another part of the first parasitic capacitance that can be formed between the part of the resistive element and the insulating film, and between the other part of the resistive element and the insulating film A second parasitic capacitance that can be formed in
A semiconductor device further comprising: a parasitic resistance that can be formed between the first and second parasitic capacitors in the substrate.   The semiconductor device according to claim 1, wherein the substrate and the well are P-type.   The semiconductor device according to claim 2, wherein the substrate is P-type.

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