Low cost and mask reduction method for high voltage devices
First Claim
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1. A method, comprising:
- a) forming an unpatterned first layer of a second conductivity type above a semiconductor substrate of a first conductivity type;
b) forming one or more isolation structures of the first conductivity type, wherein the one or more isolation structures extend in depth through the first layer of the second conductivity type and to the semiconductor substrate of the first conductivity type;
c) forming a region of the first conductivity type with a first well mask in a portion of the first layer that is isolated by the one or more isolation structures, and after forming the region of the first conductivity type, increasing a size of openings of the first well mask; and
thend) forming a punch-through stopper of the second conductivity type under the region of the first conductivity type that is isolated by the one or more isolation structures, wherein the punch-through stopper of the second conductivity type is heavily doped compared to the first layer of the second conductivity type.
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Abstract
Aspects of the present disclosure provides a device comprising a P-type semiconductor substrate, an N-type tub above the semiconductor substrate, a P-type region provided in the N-type tub isolated by one or more P-type isolation structures, and an N-type punch-through stopper provided under the P-type regions isolated by the isolation structure(s). The punch-through stopper is heavily doped compared to the N-type tub. The P-type region has a width between the two isolation structures that is equal to or less than that of the N-type punch-through stopper.
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11 Claims
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1. A method, comprising:
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a) forming an unpatterned first layer of a second conductivity type above a semiconductor substrate of a first conductivity type; b) forming one or more isolation structures of the first conductivity type, wherein the one or more isolation structures extend in depth through the first layer of the second conductivity type and to the semiconductor substrate of the first conductivity type; c) forming a region of the first conductivity type with a first well mask in a portion of the first layer that is isolated by the one or more isolation structures, and after forming the region of the first conductivity type, increasing a size of openings of the first well mask; and
thend) forming a punch-through stopper of the second conductivity type under the region of the first conductivity type that is isolated by the one or more isolation structures, wherein the punch-through stopper of the second conductivity type is heavily doped compared to the first layer of the second conductivity type. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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Specification