Active solid-state devices (e.g. – transistors – solid-state diode – Gate arrays – Having specific type of active device
Reexamination Certificate
2000-07-12
2003-07-29
Flynn, Nathan J. (Department: 2826)
Active solid-state devices (e.g., transistors, solid-state diode
Gate arrays
Having specific type of active device
C257S202000, C257S203000, C257S204000, C257S205000, C257S296000, C257S297000, C257S298000, C257S299000, C257S300000, C257S368000, C257S797000
Reexamination Certificate
active
06600180
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a semiconductor device and a method of manufacturing the same, and more particularly, it relates to a semiconductor device having a plurality of types of transistors and a method of manufacturing the same.
2. Description of the Background Art
In recent years, refinement and multi-functionalization of a semiconductor device progress to develop a semiconductor device comprising a plurality of circuit parts having different functions and having a plurality of types of transistors.
For example, a system LSI comprises a mass-storage memory cell part, a logic part operating at a high speed, a peripheral circuit part and the like. In the system LSI, transistors forming the respective circuit parts are different in required performance from each other, leading to the necessity of arranging a plurality of types of transistors.
While a plurality of types of masks must be prepared in order to form the transistors, the number of the types of the required masks is increased in proportion to the number of the types of the transistors, to disadvantageously complicate manufacturing steps and increase the manufacturing cost.
SUMMARY OF THE INVENTION
A semiconductor device according to a first aspect of the present invention at least comprises a first impurity region of a first impurity concentration having a first pattern formed in a target layer, a second impurity region having a second pattern symmetrical with the first pattern formed in the target layer with a second impurity concentration and a symmetrical third impurity region having a third impurity concentration corresponding to the total of the first and second impurity concentrations formed in the target layer.
In the semiconductor device according to the first aspect, three types of impurity regions can be obtained through two impurity introduction steps by forming the third impurity region in steps of forming the first and second impurity regions, for example, whereby the semiconductor device can be obtained through simplified manufacturing steps.
According to a second aspect of the present invention, the first and second patterns are rotation-symmetrical.
In the semiconductor device according to the second aspect, the first and second impurity regions are so rotation-symmetrically arranged that the first impurity region can be formed by introducing an impurity through an exposure mask for implantation having a pattern corresponding to the first impurity region and the second impurity region can be formed by thereafter rotating the exposure mask for implantation, for example, whereby the number of types of exposure mask for implantations can be reduced for manufacturing the semiconductor device at a low cost.
According to a third aspect of the present invention, the first and second patterns are line-symmetrical.
In the semiconductor device according to the third aspect, the first and second impurity regions are so line-symmetrically arranged that the first impurity region can be formed by introducing an impurity through an exposure mask for implantation having a pattern corresponding to the first impurity region and the second impurity region can be formed by thereafter turning over the exposure mask for implantation, for example, whereby the number of types of exposure mask for implantations can be reduced for manufacturing the semiconductor device at a low cost.
According to a fourth aspect of the present invention, the first and second impurity concentrations are different from each other.
In the semiconductor device according to the fourth aspect, circuits having different functions can be formed on the basis of the first and second impurity regions by rendering the first and second impurity concentrations different from each other.
According to a fifth aspect of the present invention, the first and second impurity concentrations are identical to each other.
In the semiconductor device according to the fifth aspect, first and second impurity regions symmetrical also in concentration can be obtained by rendering the first and second impurity concentrations identical to each other and a plurality of semiconductor devices identical in structure to each other can be obtained by dividing the first and second impurity regions to include the third impurity region respectively. Thus, the manufacturing cost for the semiconductor device can be reduced.
An exposure mask for implantation according to a sixth aspect of the present invention is employed for manufacturing the semiconductor device according to the first aspect and used in a first or second arrangement state to satisfy the symmetry between the first and second patterns for forming a pattern for implanting an impurity into the target layer corresponding to the first impurity region and the third impurity region when used in the first arrangement state and implanting an impurity into the target layer in regions corresponding to the second impurity region and the third impurity region when used in the second arrangement state.
In the exposure mask for implantation according to the sixth aspect, the third impurity region can be formed in steps of forming the first and second impurity regions.
A semiconductor device according to a seventh aspect of the present invention at least comprises a plurality of first impurity regions of a first impurity concentration having predetermined patterns formed in a target layer and a symmetrical second impurity region having a second impurity concentration integral times the first impurity concentration formed in the target layer, and the respective predetermined patterns of the plurality of first impurity regions are formed in symmetry.
In the semiconductor device according to the seventh aspect, the second impurity region having a concentration obtained by multiplying the first impurity concentration by the number of the first impurity regions can be obtained as the maximum concentration region, and a plurality of types of impurity regions having different concentrations ranging from the first impurity concentration to the aforementioned maximum concentration can be formed with a single type of exposure mask for implantation depending on the pattern formed on the exposure mask for implantation.
According to an eighth aspect of the present invention, each of the predetermined patterns of the plurality of first impurity regions is rotation-symmetrical.
In the semiconductor device according to the eighth aspect, the plurality of first impurity regions are so rotation-symmetrically arranged that the initial first impurity region can be formed by introducing an impurity through an exposure mask for implantation having a pattern corresponding to the first impurity regions and the second first impurity region can be formed by thereafter rotating the exposure mask for implantation, for example, whereby the number of types of exposure mask for implantations can be reduced and the manufacturing cost for the semiconductor device can also be reduced.
According to a ninth aspect of the present invention, each of the predetermined patterns of the first impurity regions is line-symmetrical.
In the semiconductor device according to the ninth aspect, the plurality of first impurity regions are so line-symmetrically arranged that the initial first impurity region can be formed by introducing an impurity through an exposure mask for implantation having a pattern corresponding to the first impurity regions and the second first impurity region can be formed by thereafter turning over the exposure mask for implantation, for example, whereby the number of types of exposure mask for implantations can be reduced and the manufacturing cost for the semiconductor device can also be reduced.
A method of manufacturing a semiconductor device according to a tenth aspect of the present invention comprises a step of (a) forming an implantation pattern at least having a first impurity region of a first impurity concentration having a first pattern formed in a target layer, a second impurity re
Sayama Hirokazu
Ueno Syuuichi
Yamashita Tomohiro
Flynn Nathan J.
Sefer Ahmed N.
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