FinFET Fin Damage Reduction via STI Recess and Capping

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Solution Overview

Problem

Existing bulk FinFET devices suffer from punch-through leakage due to fin damage caused by ion scattering during conventional well/PTS implantation processes, leading to increased static power consumption.

Innovation Solution

The method involves recessing the source trench isolation (STI) material to expose only the upper portion of the fins, allowing for well/PTS dopant implantation without damaging the fins, followed by forming a capping layer and performing a fin cut to maintain the integrity of the fin structure, thereby reducing fin damage and leakage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If well/PTS implantation is conducted after fin/STI formation with SiO2 layer encapsulation, then the fin structure is protected during fabrication, but Si lattice damage occurs to the fin from ion scattering due to the SiO2 layer

Engineering Contradiction:

Improvefin structure integrityVSAvoidion scattering damage

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The STI material is recessed before the well/PTS implantation step to expose only the upper portion of the fins. This preliminary action removes the harmful SiO2 encapsulation that causes ion scattering, allowing clean dopant implantation without fin damage while still maintaining the fin structure through subsequent capping layer formation

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The fin structure is divided into two sections: an upper portion that is exposed for clean implantation and a lower portion that remains covered by STI material. This segmentation allows selective doping of the upper fin region while protecting the lower region, preventing lattice damage from ion scattering

Inventive Principle:

Principle #1Segmentation

2Manufacturing precision

If conventional well/PTS implantation is performed with full fin exposure, then complete dopant coverage is achieved, but fin damage increases leading to punch-through leakage

Engineering Contradiction:

Improvedopant implantation uniformityVSAvoidpunch-through leakage

Core Design Contradiction:

Manufacturing precisionVSObject-generated harmful factors

Solution Approach 1:

The implantation process is applied locally only to the upper portion of the fins that are exposed after STI recession. This local quality approach ensures uniform dopant coverage in the critical upper region where complete coverage is needed, while avoiding ion scattering damage to the lower fin regions that would cause punch-through leakage

Inventive Principle:

Principle #3Local quality

3Reliability

If STI material is recessed to expose fins for implantation, then ion scattering damage is prevented, but additional process steps are required

Engineering Contradiction:

Improvefin damage reductionVSAvoidfabrication process steps

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The STI recession step is merged with the preparation for well/PTS implantation, combining the protective function of STI with the implantation access requirement. The capping layer formation is then merged with the fin protection strategy, where the same capping layer that protects during implantation also serves to define the fin structure after the process

Inventive Principle:

Principle #5Merging (Combining)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This approach effectively minimizes fin damage and enhances device yield by preventing scattering effects during implantation, leading to reduced channel effects and lower static power consumption.

Implementation Method 1

implanting the semiconductor device

Methodology Applied

Scientific EffectIon Implantation: Ion Implantation

Implementation Method 2

ion scattering due to the SiO2 layer encapsulation of the fins

Methodology Applied

Scientific EffectScattering: Scattering

Data Source

PatentUS10692775B2Fin damage reduction during punch through implantation of FinFET device

Publication Date: 2020.06.23 APPLIED MATERIALS INC

AI summary

Disclosed are methods of forming a semiconductor device, such as a finFET device. One non-limiting method may include providing a semiconductor device including a substrate and a plurality of fins extending from the substrate, and forming a source trench isolation (STI) material over the semiconductor device. The method may further include recessing the STI material to reveal an upper portion of the plurality of fins, implanting the semiconductor device, and forming a capping layer over the plurality of fins and the STI material. The method may further include removing a first fin section of the plurality of fins and a first portion of the capping layer, wherein a second fin section of the plurality of fins remains following removal of the first fin section.