Method of forming a pocket implant region after formation of composite insulator spacers
First Claim
1. A method of forming a metal oxide semiconductor field effect transistor (MOSFET), on a semiconductor substrate, featuring formation of a combination of two pocket implant regions, one completely surrounding a lightly doped source/drain region and the other formed adjacent to the sides of a heavily doped source/drain region, comprising the steps of:
- providing a gate insulator layer on a semiconductor substrate comprised with a first conductivity type, with a gate structure overlying said gate insulator layer;
forming a said lightly doped source/drain (LDD) region of a second conductivity type, in portion of said semiconductor substrate not covered by said gate structure;
forming first pocket region of a first conductivity type in a portion of said semiconductor substrate not covered by said gate structure, with said first pocket region completely surrounding said LDD region, and wherein said first pocket region, completely enclosing said LDD region, is comprised with a dopant level greater than the dopant level of said semiconductor substrate;
forming a composite insulator spacer on sides of said gate structure, with said composite insulator spacer comprised of an underlying L shaped insulator component, and comprised of an overlying insulator component;
forming said heavily doped source/drain region of a second conductivity type, in a portion of said semiconductor substrate not covered by said gate structure or by said composite insulator spacer;
removing said overlying insulator component of said composite insulator spacer; and
forming a second pocket region of a first conductivity type in a portion of said semiconductor substrate underlying horizontal portion of L shaped insulator component and adjacent to sides of said heavily doped source/drain region, with said second pocket region comprised with a dopant level greater than the dopant level of said first pocket region.
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Accused Products
Abstract
A process for forming a MOSFET device featuring a pocket region placed adjacent to only a top portion of the sides of a heavily doped source/drain region, has been developed. The process features forming a heavily doped source/drain region in an area of a semiconductor substrate not covered by the gate structure or by composite insulator spacers located on the sides of the gate structure. Selective removal of an overlying insulator component of the composite insulator spacer allows a subsequent pocket implant region to be formed in an area of the semiconductor substrate directly underlying a horizontal portion of a remaining L shaped insulator spacer component. The location of the pocket region, formed butting only the top portions of the sides of the heavily doped source/drain region, reduces the risk of punch through current while limiting the impact of junction capacitance.
22 Citations
27 Claims
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1. A method of forming a metal oxide semiconductor field effect transistor (MOSFET), on a semiconductor substrate, featuring formation of a combination of two pocket implant regions, one completely surrounding a lightly doped source/drain region and the other formed adjacent to the sides of a heavily doped source/drain region, comprising the steps of:
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providing a gate insulator layer on a semiconductor substrate comprised with a first conductivity type, with a gate structure overlying said gate insulator layer;
forming a said lightly doped source/drain (LDD) region of a second conductivity type, in portion of said semiconductor substrate not covered by said gate structure;
forming first pocket region of a first conductivity type in a portion of said semiconductor substrate not covered by said gate structure, with said first pocket region completely surrounding said LDD region, and wherein said first pocket region, completely enclosing said LDD region, is comprised with a dopant level greater than the dopant level of said semiconductor substrate;
forming a composite insulator spacer on sides of said gate structure, with said composite insulator spacer comprised of an underlying L shaped insulator component, and comprised of an overlying insulator component;
forming said heavily doped source/drain region of a second conductivity type, in a portion of said semiconductor substrate not covered by said gate structure or by said composite insulator spacer;
removing said overlying insulator component of said composite insulator spacer; and
forming a second pocket region of a first conductivity type in a portion of said semiconductor substrate underlying horizontal portion of L shaped insulator component and adjacent to sides of said heavily doped source/drain region, with said second pocket region comprised with a dopant level greater than the dopant level of said first pocket region. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. A method of forming a metal oxide semiconductor field effect transistor (MOSFET), on a semiconductor substrate, featuring formation of a combination of pocket implant regions, with a second pocket region comprised of a deep P type pocket region formed after heavily doped source/drain and composite insulator spacer formation, comprising the steps of:
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forming silicon dioxide gate insulator layer on a P type semiconductor substrate;
forming conductive gate structure on said silicon dioxide gate insulator layer;
forming N type, lightly doped source/drain (LDD) region in a portion of said P type semiconductor substrate not covered by said conductive gate structure;
forming a first pocket region, a shallow, P type pocket region formed in an area of said P type semiconductor substrate not covered by said conductive gate structure, with said shallow, P type pocket region completely surrounding and enclosing said N type LDD region, and wherein said shallow, P type pocket region is comprised with a P type dopant level greater than the P type dopant level of said P type semiconductor substrate;
forming a silicon nitride layer;
forming a silicon oxide layer;
performing an anisotropic reactive ion etch procedure to form a composite insulator spacer on sides of said conductive gate structure, with said composite insulator spacer comprised of an underlying L shaped silicon nitride component, and comprised of an overlying silicon oxide component;
forming a heavily doped N type source/drain region in an area of said P type semiconductor substrate not covered by said conductive gate structure or by said composite insulator spacer;
removing said overlying silicon oxide component of said composite insulator spacer;
forming said second pocket region, said deep, P type pocket region, formed using an implantation angle between about 10 to 30°
in a portion of said P type semicondutor substrate underlying a horizontal portion of said L shaped silicon nitride insulator component of said composite insulator spacer, with said deep, P type pocket region comprised with a P type dopant level greater than the P type dopant level of said shallow pocket region; and
performing an anneal procedure. - View Dependent Claims (16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27)
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Specification