Structure and fabrication method using latch-up implantation for improving latch-up immunity in CMOS fabrication process
First Claim
1. A structure using latch-up implantation to improve latch-up immunity in CMOS fabrication process, the structure comprising:
- a substrate, having a first conductive type;
a well, formed in the substrate and having a second conductive type;
a first MOS transistor formed in the second conductive type well, having a first source and a first drain regions with a first conductive type and a gate;
a second MOS transistor formed in the first conductive type substrate, having a second source and a second drain regions with a second conductive type and a gate;
a first lightly doped region surrounding a bottom and edges of the first source region in the well, the edges of the first source region excluding the edge at a near side of the first drain region, and the first lightly doped region having a first conductive type;
a second lightly doped region surrounding a bottom and edges of the second source region in the substrate, the edges of the second source region excluding the edge at a near side of the second drain region, and the second lightly doped region having a second conductive type;
a first heavily doped region with a second conductive type in the second conductive type well, the first heavily doped region being near and with a distance to the first lightly doped region; and
a second heavily doped region with a first conductive type in the first conductive type substrate, the second heavily doped region being near and with a distance to the second lightly doped region.
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Abstract
A structure and fabrication method using latch-up implantation to improve latch-up immunity in CMOS circuit. The impedance of parasitic SCR conducting path is raised by performing an ion-implantation process on a cathode and an anode of a parasitic SCR which may induce latch-up phenomenon. Thus, the parasitic SCR is thus not easily to be conducted with a higher resistance to noise. Therefore, the latch-up immunity can be improved. In addition, the ion implantation process can be performed to achieve the objective of preventing latch-up effect without consuming more area for layout, thus greatly enhances the flexibility in circuit design.
48 Citations
21 Claims
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1. A structure using latch-up implantation to improve latch-up immunity in CMOS fabrication process, the structure comprising:
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a substrate, having a first conductive type;
a well, formed in the substrate and having a second conductive type;
a first MOS transistor formed in the second conductive type well, having a first source and a first drain regions with a first conductive type and a gate;
a second MOS transistor formed in the first conductive type substrate, having a second source and a second drain regions with a second conductive type and a gate;
a first lightly doped region surrounding a bottom and edges of the first source region in the well, the edges of the first source region excluding the edge at a near side of the first drain region, and the first lightly doped region having a first conductive type;
a second lightly doped region surrounding a bottom and edges of the second source region in the substrate, the edges of the second source region excluding the edge at a near side of the second drain region, and the second lightly doped region having a second conductive type;
a first heavily doped region with a second conductive type in the second conductive type well, the first heavily doped region being near and with a distance to the first lightly doped region; and
a second heavily doped region with a first conductive type in the first conductive type substrate, the second heavily doped region being near and with a distance to the second lightly doped region. - View Dependent Claims (2, 3)
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4. A structure using latch-up implantation to improve latch-up immunity in CMOS fabrication process, the structure comprising:
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a substrate, having a first conductive type;
a well, formed in the substrate and having a second conductive type;
a first MOS transistor formed in the second conductive type well, having a first source and a first drain regions with a first conductive type and a gate;
a second MOS transistor formed in the first conductive type substrate, having a second source and a second drain regions with a second conductive type and a gate;
a first lightly doped region surrounding a bottom and edges of the first source region in the well, the edges of the first source region excluding the edge at a near side of the first drain region, and the first lightly doped region having a first conductive type;
a first heavily doped region with a second conductive type in the second conductive type well, the first heavily doped region being near and with a distance to the first lightly doped region; and
a second heavily doped region with a first conductive type in the first conductive type substrate, the second heavily doped region being near and with a distance to a second lightly doped region, wherein the second lightly doped region is located in the first conductive type substrate. - View Dependent Claims (5, 6)
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7. A structure using latch-up implantation to improve latch-up immunity in CMOS fabrication process, the structure comprising:
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a substrate, having a first conductive type;
a well, formed in the substrate and having a second conductive type;
a first MOS transistor formed in the second conductive type well, having a first source and a first drain regions with a first conductive type and a gate;
a second MOS transistor formed in the first conductive type substrate, having a second source and a second drain regions with a second conductive type and a gate;
a first lightly doped region surrounding a bottom and edges of the second source region in the substrate, the edges of the second source region excluding the edge at a near side of the second drain region, and the first lightly doped region having a second conductive type;
a first heavily doped region with a second conductive type in the second conductive type well, the first heavily doped region being near and with a distance to the first lightly doped region; and
a second heavily doped region with a first conductive type in the first conductive type substrate, the second heavily doped region being near and with a distance to a second lightly doped region, wherein the second lightly doped region is located in the first conductive type substrate. - View Dependent Claims (8, 9)
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10. A method using latch-up implantation to improve latch-up immunity in CMOS fabrication process, the method comprising:
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providing a first conductive type substrate comprising a second conductive type well thereon;
forming a first MOS in the second conductive type well and a first heavily doped region with a first conductive type in the first conductive type substrate;
forming a second MOS in the first conductive type substrate and a second heavily doped region with a second conductive type in the second conductive type well;
forming a first lightly doped region with a first conductive type surrounding a bottom and edges of a source region of the first MOS in the well, wherein the edges are those edges except the edge being at near to the drain region of the first MOS; and
forming a second lightly doped region with a second conductive type surrounding a bottom and edges of a source region of the second MOS in the substrate, wherein the edges are those edges except the edge being at near to the drain region of the second MOS. - View Dependent Claims (11, 12, 13)
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14. A method using latch-up implantation to improve latch-up immunity in CMOS fabrication process, the method comprising:
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providing a first conductive type substrate comprising a second conductive type well thereon;
forming a first MOS in the second conductive type well and a first heavily doped region with a first conductive type in the first conductive type substrate;
forming a second MOS in the first conductive type substrate and a second heavily doped region with a second conductive type in the second conductive type well;
forming a first lightly doped region with a first conductive type surrounding a bottom and edges of a source region of the first MOS in the well, wherein the edges are those edges except the edge being at near to the drain region of the first MOS. - View Dependent Claims (15, 16, 17)
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18. A method using latch-up implantation to improve latch-up immunity in CMOS fabrication process, the method comprising:
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providing a first conductive type substrate comprising a second conductive type well thereon;
forming a first MOS in the second conductive type well and a first heavily doped region with a first conductive type in the first conductive type substrate;
forming a second MOS in the first conductive type substrate and a second heavily doped region with a second conductive type in the second conductive type well;
forming a first lightly doped region with a second conductive type surrounding a bottom and edges of a source region of the second MOS in the substrate, wherein the edges are those edges except the edge being at near to the drain region of the second MOS. - View Dependent Claims (19, 20, 21)
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Specification