JP3150109B2 - Polysilicon resistance element - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polysilicon resistance element, and more particularly to a polysilicon resistance element whose resistance can be changed by an external bias condition.

[0002]

2. Description of the Related Art Polysilicon resistors have been frequently used in the past because they have a higher insulating property from a semiconductor substrate in which a semiconductor element is formed than diffused resistors.
There is a drawback that the accuracy of the resistance value is poor. Various attempts have been made to compensate for this drawback. One of them is disclosed in Japanese Patent Application Laid-Open No.
A polysilicon resistance element capable of extending the linearity of voltage characteristics to a high current region is disclosed. 5 and 6 are views showing the contents of the invention according to the publication, FIG. 5 (a) is a plan view of a polysilicon resistor, FIG. 5 (b) is a cross-sectional view taken along the line AA, and FIG. 4 is a graph showing current-voltage characteristics of a silicon resistor. In this publication, a resistance value control electrode 8 is formed on a polysilicon resistor 83 via an insulating film 82.
6, a predetermined voltage is applied to this electrode to generate a charge-inducing layer (depletion layer) 92 from the surface of the polysilicon resistor 83 toward the inside thereof, as shown in FIG. The cross-sectional area of the passage is reduced. By doing so, as shown in FIG. 6, the linear region 1 in the low current region of the current-voltage characteristic 101 of the conventional polysilicon resistance element is formed.
02 is extended to the high current region, and is changed to the current-voltage characteristic 103, and the absolute value of the resistance value is changed so as to increase as a whole.

[0003]

However, this structure requires a control electrode that covers a part of the polysilicon resistor, and requires a space for the control electrode at least above the polysilicon resistor. However, there is a problem that it is difficult to apply to a polysilicon resistor having a short length.

A main object of the present invention is to extend the linearity of the current-voltage characteristic of the resistance value to a high current region and to change the absolute value of the resistance value to a large value even for a polysilicon resistor having a short length. It is an object of the present invention to provide a polysilicon resistance element which can be used.

[0005]

A polysilicon resistance element according to the present invention comprises a semiconductor substrate of one conductivity type, a first insulating film provided on the semiconductor substrate of one conductivity type, and a first insulating film provided on the first insulating film. A polysilicon resistor, and a polysilicon layer for resistance bias formed at the same time as the polysilicon resistor and arranged in proximity to the polysilicon resistor;
A second insulating film covering the first insulating film including the polysilicon resistor and the resistance bias polysilicon layer; and a second insulating film on the polysilicon resistor and the resistance bias polysilicon layer. It is characterized by comprising a resistance contact and a resistance bias contact respectively opened in a predetermined portion, and a resistance wiring and a bias wiring respectively connected to the resistance contact and the resistance bias contact. As a typical form, the polysilicon layer for resistance bias is:
It is characterized by being formed so as to surround at least both sides in the length direction thereof while maintaining a predetermined interval with respect to the polysilicon resistor, and in the above-described configuration, when there are a plurality of polysilicon resistors, Wherein the predetermined interval can take different values for each of the polysilicon resistors. Further, in the configuration described above, the impurity contained in the polysilicon resistor is a P-type or an N-type. In this case, the bias wiring is applied with a constant voltage higher or lower than the resistance wiring, respectively.

[0006]

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described with reference to FIG. FIG. 1A is a plan view of a polysilicon resistance element, and FIG. 1B is a sectional view taken along a line X-
It is sectional drawing which followed X.

[0008] A polysilicon resistor having such a short length that no control electrode as in the conventional example of FIG. In this embodiment, three first polysilicon resistors 3, second polysilicon resistors 4, and third polysilicon resistors 5 having the same shape are formed. A resistance biasing polysilicon layer 6 surrounding at least the length direction of these polysilicon resistors at equal intervals is provided.
It is formed simultaneously with the formation of the polysilicon resistor. A protective insulating film 11 is formed on the polysilicon resistor and the resistance biasing polysilicon layer 6, and a resistance contact 7 is formed on the protection insulating film 11 on the polysilicon resistor and a resistance insulating film 11 on the resistance biasing polysilicon layer 6. A contact 8 for resistance bias is opened in the protective insulating film 11. Further, the resistance contact 7 is connected to a resistance wiring 9 and the resistance bias polysilicon layer 6 is connected to another semiconductor element or an external terminal (not shown) through a resistance bias wiring 10.

[0009] The polysilicon resistor having such a structure is as follows.
When the polysilicon is doped with an impurity such as boron, a constant potential higher than the potential applied to the polysilicon resistor is applied to the resistance bias wiring 10, and FIG.
As shown in (b), a depletion layer 12 is induced in the polysilicon resistor from the lateral direction, and the resistance is adjusted to a higher value. When the polysilicon is doped with an impurity such as phosphorus, the potential relationship may be set to the opposite.

As described above, according to the present embodiment, it is possible to obtain the effect that the resistance value control means can be formed regardless of the length of the polysilicon resistor, especially when the length of the polysilicon resistor is short.

Next, a second embodiment of the present invention will be described with reference to FIG. FIG. 2A is a plan view of the polysilicon resistance element, and FIG. 2B is a sectional view taken along a line YY in FIG.
FIG.

The structure below the polysilicon resistor is the first structure.
This is the same as the embodiment. A structure in which three same-shaped fourth polysilicon resistors 13, fifth polysilicon resistors 14, and sixth polysilicon resistors 15 as in the first embodiment are formed on the underlying oxide film 2 is shown. At least the length direction of these polysilicon resistors is set at a constant interval with respect to each resistor and is different from that of the three polysilicon resistors, so that a resistor bias polysilicon layer is formed. 16 are surrounding. The spacing is made wider in the order of the fourth polysilicon resistor 13, the fifth polysilicon resistor 14, and the sixth polysilicon resistor 15.

The polysilicon resistor having such a structure is as follows.
When the polysilicon is doped with an impurity such as boron, a constant potential higher than the potential of the resistance wiring 19 applied to the polysilicon resistor is applied to the resistance bias wiring 20, and FIG. As shown in FIG. 3, depletion layers 23, 24, and 25 are induced in the fourth polysilicon resistor 13, the fifth polysilicon resistor 14, and the sixth polysilicon resistor 15 from the lateral direction, and the resistance value is increased. Adjust to a higher one. The resistance values of the fourth polysilicon resistor 13, the fifth polysilicon resistor 14, the sixth polysilicon resistor 1
It becomes higher in the order of 5.

As described above, in the second embodiment, in addition to the effect that the resistance value control means can be formed irrespective of the length of the polysilicon resistor, in addition to the effect that the polysilicon resistor and the polysilicon layer for the resistance bias are used. By changing the interval,
An effect is also obtained that polysilicon resistors exhibiting various resistance values can be obtained.

Next, a first related technique related to the present invention will be described with reference to FIG. FIG. 3A is a plan view of the polysilicon resistance element, and FIG. 3B is a cross-sectional view taken along a cutting line ZZ in FIG. 3A. In this related technique , a diffusion layer is used as bias means for a polysilicon resistor.

In the P-type semiconductor substrate 1, N +
The diffusion layer 36 is selectively formed. This P-type semiconductor substrate 1
A polysilicon resistor having the same shape as that of the first embodiment is formed on the underlying oxide film 2 grown in the above manner so as to be included in the region above the N + diffusion layer 36 for resistance bias. In this manner, three identically shaped seventh polysilicon resistors 33, eighth polysilicon resistors 34, and ninth polysilicon resistors 35 are obtained.

The polysilicon resistor having such a structure is as follows.
When the polysilicon is doped with an impurity such as boron, a constant potential higher than the potential applied to the polysilicon resistor is applied to the resistance bias wiring 40, and FIG.
As shown in (b), a depletion layer 32 is induced in the polysilicon resistor from below, and the resistance value is adjusted to a higher value.

In this related technique , since the resistance bias polysilicon layer of the first embodiment is not required,
In addition to the effect obtained in the first embodiment, an effect that an occupied area for obtaining a polysilicon resistor can be reduced can also be obtained.

Next, a second related technique related to the present invention will be described with reference to FIG. FIG. 4A is a plan view of the polysilicon resistance element, and FIG. 4B is a cross-sectional view taken along the line WW of FIG. 4A. In this related art, the first
As in the related art 1 , a diffusion layer is used as a bias means for the polysilicon resistor.

In the P-type semiconductor substrate 1, N +
The diffusion layers 66, 67, 68 are selectively formed. On the underlying oxide film 2 grown on the P-type semiconductor substrate 1, three polysilicon resistors having the same shape as that of the first embodiment are placed above the N + diffusion layers 66, 67, 68 for resistance bias. It is formed in a shape that is included in the area. In this manner, three identically shaped tenth polysilicon resistors 53,
An eleventh polysilicon resistor 54 and a twelfth polysilicon resistor 55 are obtained. A tenth polysilicon resistor 53,
A protective insulating film 11 covers the eleventh polysilicon resistor 54 and the twelfth polysilicon resistor 55, a resistor contact 57 is opened on each polysilicon resistor, and a resistance bias N + diffusion layer 66 is formed. The contact 58 for resistance bias is opened also on 67 and 68, respectively. Through these contacts, the resistance wiring 59 and the resistance bias wiring 61, the polysilicon resistor and the N + diffusion layer for resistance bias are connected to another semiconductor element or an external terminal.

The polysilicon resistor having such a structure is as follows.
When the polysilicon is doped with an impurity such as boron, the resistance bias wiring 60, the resistance bias wiring 61, and the resistance bias wiring 62 have a potential higher than the potential of the resistance wiring 59 applied to the polysilicon resistor. A high and constant potential is applied, and the resistance bias wiring 60, the resistance bias wiring 61, and the resistance bias wiring 62 are set higher in this order. By doing so, as shown in FIG.
Depletion layers 72, 73, and 74 are induced from below in each of the tenth polysilicon resistor 53, the eleventh polysilicon resistor 54, and the twelfth polysilicon resistor 55,
The resistance value is set to a high value. As the resistance value, the tenth
Polysilicon resistor 53, eleventh polysilicon resistor 5
4 and the twelfth polysilicon resistor 55 increases in this order.

As described above, in the second related art , the first
In addition to the effects obtained by the related art , by applying various constant voltages to the N + diffusion layer for resistance bias, it is possible to obtain an effect that a polysilicon resistor having various resistance values can be obtained.

[0023]

As described above, according to the present invention,
Since the biasing means for the polysilicon resistor is provided laterally or below the polysilicon resistor via the insulating film, the resistance value of the polysilicon resistor can be set high regardless of the length of the polysilicon resistor. Further, by changing the horizontal distance between the polysilicon resistor and the bias means, or by setting the potential of the polysilicon resistor and the bias means located below to various values, the polysilicon resistor can have various high values. The effect that the resistance value can be set is also obtained.

[Brief description of the drawings]

FIG. 1 is a plan view and a cross-sectional view of a polysilicon resistance element obtained according to a first embodiment of the present invention.

FIG. 2 is a plan view and a cross-sectional view of a polysilicon resistance element obtained according to a second embodiment of the present invention.

FIGS. 3A and 3B are a plan view and a cross-sectional view of a polysilicon resistance element obtained by a first related technique related to the present invention. FIGS.

FIG. 4 is a plan view and a cross-sectional view of a polysilicon resistance element obtained by a second related technique related to the present invention.

FIG. 5 is a plan view and a sectional view of a conventional polysilicon resistance element.

6 is a graph showing current-voltage characteristics of the conventional polysilicon resistance element shown in FIG.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 P-type semiconductor substrate 2 underlying oxide film 3 first polysilicon resistor 4 second polysilicon resistor 5 third polysilicon resistor 6, 16 polysilicon layer for resistance bias 7, 17, 37, 57, 87 resistance contact 8, 18, 38, 58 Resistance bias contact 9, 19, 39, 59, 89 Resistance wiring 10, 20, 40, 60, 61, 62 Resistance bias wiring 11 Protective insulating film 12, 22, 23, 24, 32 , 72, 73, 74
Depletion layer 13 fourth polysilicon resistor 14 fifth polysilicon resistor 15 sixth polysilicon resistor 33 seventh polysilicon resistor 34 eighth polysilicon resistor 35 ninth polysilicon resistor 36, 66, 67, 68 N + diffusion layer for resistance bias 53 10th polysilicon resistor 54 11th polysilicon resistor 55 twelfth polysilicon resistor 81 insulating substrate 82 insulating film 83 polysilicon resistor 86 resistance control electrode 92 charge induction layer 101, 103 Current-voltage characteristic 102 Linear region

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H01L 27/04 H01L 21/822

Claims (4)

(57) [Claims] 1. A semiconductor substrate of one conductivity type, a first insulating film provided on the semiconductor substrate of one conductivity type, a polysilicon resistor provided on the first insulating film, and the polysilicon resistor A polysilicon layer for resistance bias formed at the same time and arranged in proximity to the polysilicon resistor;
A second insulating film covering the first insulating film including the polysilicon resistor and the resistance bias polysilicon layer; and a second insulating film on the polysilicon resistor and the resistance bias polysilicon layer. A polysilicon resistance element comprising: a resistance contact and a resistance bias contact respectively opened in a predetermined portion; and a resistance wiring and a bias wiring connected to the resistance contact and the resistance bias contact, respectively. 2. The resistance biasing polysilicon layer comprises:
2. The polysilicon resistance element according to claim 1, wherein the polysilicon resistance element is formed so as to surround at least both sides in the length direction thereof while maintaining a predetermined distance from the polysilicon resistor. 3. The polysilicon resistance element according to claim 1, wherein when there are a plurality of said polysilicon resistors, said predetermined interval can take different values for each of said polysilicon resistors. 4. When the impurity contained in the polysilicon resistor is P-type or N-type, a constant voltage higher or lower than the resistance wiring is applied to the bias wiring, respectively. 4. The polysilicon resistance element according to any one of claims 1 to 3.