Semiconductor devices and methods of manufacturing the same
First Claim
1. A method of manufacturing a semiconductor device, comprising:
- selectively forming, on a semiconductor substrate, an oxidation-resistant layer having a masking action against oxidation;
introducing an impurity of second conductivity type to said semiconductor substrate with said oxidation-resistant layer used as a mask, thereby forming a second well in said semiconductor substrate;
selectively oxidizing a surface area of said second well with said oxidation-resistant layer used as a mask, thereby forming a LOCOS layer in said second well;
removing said oxidation-resistant layer;
introducing an impurity of first conductivity type to said semiconductor substrate with said LOCOS layer used as a mask, thereby forming a first well in said semiconductor substrate in adjacent relation to said second well;
removing said LOCOS layer;
introducing an impurity of the first conductivity type to part of said second well, thereby forming a third well in said second well; and
forming a field effect transistor in each of said first, second and third wells, by a process comprising;
after introducing a first conductivity type impurity and a second conductivity type impurity in areas of said semiconductor substrate, forming a LOCOS layer in a pattern on said semiconductor substrate to form first conductivity type and second conductivity type low-density impurity layers in said areas under the LOCOS layer, part of said LOCOS layer being formed at least around a gate insulating layer of said field effect transistor;
forming a gate electrode; and
forming a high-density impurity layer comprising a source/drain area.
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Accused Products
Abstract
Embodiments include a semiconductor device including a well structure such that well areas can be formed with a higher density of integration and a plurality of high-voltage endurable transistors can be driven independently of one another with different voltages, and a method of manufacturing the semiconductor device. The semiconductor device may include a triple well comprising a first well formed in a silicon substrate and having a first conductivity type (P-type), a second well formed in adjacent relation to the first well and having a second conductivity type (N-type), and a third well formed in the second well and having the first conductivity type (P-type). A high-voltage endurable MOSFET is provided in each of the wells. Each MOSFET has an offset area in the corresponding well around a gate insulating layer. The offset area is formed of a low-density impurity layer which is provided under an offset LOCOS layer on the silicon substrate.
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Citations
19 Claims
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1. A method of manufacturing a semiconductor device, comprising:
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selectively forming, on a semiconductor substrate, an oxidation-resistant layer having a masking action against oxidation;
introducing an impurity of second conductivity type to said semiconductor substrate with said oxidation-resistant layer used as a mask, thereby forming a second well in said semiconductor substrate;
selectively oxidizing a surface area of said second well with said oxidation-resistant layer used as a mask, thereby forming a LOCOS layer in said second well;
removing said oxidation-resistant layer;
introducing an impurity of first conductivity type to said semiconductor substrate with said LOCOS layer used as a mask, thereby forming a first well in said semiconductor substrate in adjacent relation to said second well;
removing said LOCOS layer;
introducing an impurity of the first conductivity type to part of said second well, thereby forming a third well in said second well; and
forming a field effect transistor in each of said first, second and third wells, by a process comprising;
after introducing a first conductivity type impurity and a second conductivity type impurity in areas of said semiconductor substrate, forming a LOCOS layer in a pattern on said semiconductor substrate to form first conductivity type and second conductivity type low-density impurity layers in said areas under the LOCOS layer, part of said LOCOS layer being formed at least around a gate insulating layer of said field effect transistor;
forming a gate electrode; and
forming a high-density impurity layer comprising a source/drain area. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A method of manufacturing a semiconductor device, comprising:
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forming a first well of a first conductivity type in a semiconductor substrate;
forming a second well of a second conductivity type in said semiconductor substrate;
forming a third well within said second well, said third well having said first conductivity type, said third well formed to be about ⅓
to about ½
the depth of said second well; and
forming a field effect transistor in each of said first, second and third wells, each of said transistors formed by introducing a low density impurity selected from the group consisting of an N-type impurity and a P-type impurity into areas of said semiconductor substrate, forming a LOCOS layer in a pattern on said semiconductor substrate, forming a gate electrode, and forming a high density impurity layer comprising a source/drain area, wherein at least a portion of said LOCOS layer is positioned adjacent to and in contact with a gate insulating layer and said gate electrode. - View Dependent Claims (13)
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14. A method of manufacturing a semiconductor device, comprising:
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forming a first well of a first conductivity type in a semiconductor substrate;
forming a second well of a second conductivity type in said semiconductor substrate;
forming a third well within said second well, said third well having said first conductivity type; and
forming a field effect transistor in each of said first, second and third wells, each of said transistors formed by introducing a low density impurity selected from the group consisting of an N-type impurity and a P-type impurity into areas of said semiconductor substrate, forming a LOCOS layer in a pattern on said semiconductor substrate, forming a gate electrode, and forming a high density impurity layer to act as a source/drain area. - View Dependent Claims (15, 16, 17, 18, 19)
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Specification