OPEN DRAIN INPUT/OUTPUT STRUCTURE AND MANUFACTURING METHOD THEREOF IN SEMICONDUCTOR DEVICE
First Claim
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1. A method of manufacturing a pull-up transistor for use with a Vdd terminal and an I/O pad of a semiconductor device comprising:
- forming a gate insulating layer in an active region on a first conductive-type semiconductor substrate;
forming an impurity implantation region at a predetermined first sector within the substrate by ion-implanting an impurity of a second conductive-type;
forming a gate on the gate insulating layer over at least a portion of the first sector and over a region adjacent to the first sector;
forming source and drain regions within the substrate at opposite sides of the gate by ion-implanting an impurity of the second conductive type, the first sector having been predetermined such that the impurity implantation region does not reach both the source region and the drain region;
coupling one of the source region and the drain region to the I/O pad; and
coupling the other one of the source region and the drain region to the Vdd terminal.
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Abstract
An improved pull-up transistor is provided for use as an open drain input/output structure. The transistor includes a source and a drain that define a channel between them. An impurity implantation region in the channel does not reach both the source and the drain. The impurity can reach only the source, only the drain, or none of them. As such, it presents a discontinuity, which serves as a p-type channel. The transistor therefore can act as an enhancement transistor used for pull-up. The invention can be implemented with a mask ROM embedded MCU, or an EPROM embedded MCU.
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Citations
9 Claims
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1. A method of manufacturing a pull-up transistor for use with a Vdd terminal and an I/O pad of a semiconductor device comprising:
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forming a gate insulating layer in an active region on a first conductive-type semiconductor substrate;
forming an impurity implantation region at a predetermined first sector within the substrate by ion-implanting an impurity of a second conductive-type;
forming a gate on the gate insulating layer over at least a portion of the first sector and over a region adjacent to the first sector;
forming source and drain regions within the substrate at opposite sides of the gate by ion-implanting an impurity of the second conductive type, the first sector having been predetermined such that the impurity implantation region does not reach both the source region and the drain region;
coupling one of the source region and the drain region to the I/O pad; and
coupling the other one of the source region and the drain region to the Vdd terminal. - View Dependent Claims (2, 3, 4)
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5. A pull-up transistor for use with a Vdd terminal and an I/O pad of a semiconductor device comprising:
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a semiconductor substrate of a first conductive-type;
a source region and a drain region of a second conductive type formed in the substrate and defining between them a channel region, one of the source region and the drain region being coupled with the I/O pad, the other one of the source region and the drain region being coupled with the Vdd terminal;
an impurity implantation region of impurities of a second conductive-type formed in a first sector of the channel region, the first sector reaching at most one of the source region and the drain region;
a gate insulating layer on the substrate over at least a portion of the impurity implantation region and over at least a portion of an area adjacent the impurity implantation region; and
a gate on the gate insulating layer over at least a portion of the first sector and over at least a portion of a region adjacent to the first sector. - View Dependent Claims (6, 7, 8, 9)
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Specification