# US 6,297,111 B1 · Self-aligned channel transistor and method for making same

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- Number: US 6,297,111 B1
- Document ID: US6297111B1
- Status: Granted
- Kind: B1
- Application number: 08/914,986
- Filed: 1997-08-20
- Granted: 2001-10-02
- Earliest claimed: 1997-08-20
- Assignees: Advanced Micro Devices, Inc.
- Inventors: Zoran Krivokapic
- Web page: https://patentgrep.com/patent/US6297111B1

## CPC

- H10P 30/21: {of electrically active species}
- H10D 30/0227: {having both lightly-doped source and drain extensions and source and drain regions self-aligned to the sides of the gate, e.g. lightly-doped drain [LDD] MOSFET or double-diffused drain [DDD] MOSFET}
- H10P 30/204: {into Group IV semiconductors}
- H10P 30/221: {characterised by the angle between the ion beam and the mask}
- H10P 30/222: {characterised by the angle between the ion beam and the crystal planes or the main crystal surface (characterised by the angle between the ion beam and the mask H10P30/221)}
- H10P 30/225: {of a molecular ion, e.g. decaborane}
- H10P: GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10
- H10D: INORGANIC ELECTRIC SEMICONDUCTOR DEVICES

## Abstract

A method for forming a transistor comprises the steps of: forming a gate stack on the surface of a semiconductor substrate; implanting a first dose of an impurity into the substrate at a sufficient energy to penetrate at least a portion of the gate stack to provide a portion of the impurity on the first and second sides of the gate stack, and a portion of the impurity under the gate stack; and forming source/drain regions on the first and second sides of the gate stack. The implant may be at an angle normal to the surface of the substrate at an energy sufficient such that the impurity penetrates the gate stack to reach the channel region. Alternatively, a pair of angled implants at an angle relative to a line normal to the surface of the substrate may be used.

## Claims

### Claim 1

A method for forming a semiconductor device on a semiconductor substrate having a surface, comprising the steps of:
(A) forming a gate stack on the substrate, the gate stack having a first side and a second side;
(B) forming a mask layer over the substrate, the mask layer having an opening over the gate stack and over a first and second portions of the substrate at the respective first and second side of the gate stack;
(C) implanting a first dose of an impurity into the gate stack and the substrate at a first angle relative to a line normal to the surface of the substrate greater than 7 degrees and less than 30 degrees;
(D) implanting a second dose of the impurity into the gate stack and the substrate at a second angle relative to a line normal to the surface of the substrate, the second angle being less than −7 degrees and greater than −30 degrees; and
wherein the mask layer blocks at least a portion of said first dose and said second dose to a portion of the substrate at the first and second side of the gate stack;
wherein the impurity is boron and wherein the steps (C) and (D) provide an implant region having a graded concentration profile of about 7×1017 atm/cm3 concentration in the gate stack to about 6.9×1015 atm/cm3 in the substrate underlying the gate stack.