Nanosheet Source-Drain Contacts With Deep Interface Etching

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Solution Overview

Problem

Existing nanosheet structures in semiconductor devices face performance constraints due to the metal contact material having a source-drain material positioned between the contact material and the nanosheet material, leading to high contact resistance.

Innovation Solution

A method involving deep etching of the source-drain material to expose nanosheet material, forming epitaxial contact layers, and a silicide contact layer to facilitate a direct interface between the metal contact and nanosheets, reducing contact resistance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If source-drain material is positioned between metal contact material and nanosheet material to facilitate contact formation, then contact area is increased, but contact resistance increases and carrier injection is hindered

Engineering Contradiction:

Improvecontact resistanceVSAvoidcontact structure complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent removes the source-drain material between the metal contact and nanosheet by etching it away, exposing the nanosheet directly. This extraction of the problematic intermediate layer eliminates the barrier to carrier injection while maintaining contact stability through the epitaxial silicon interface.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

Instead of having metal contact directly on source-drain (conventional approach), the patent inverts the structure by etching through the source-drain to expose the nanosheet, then forming epitaxial silicon on the exposed nanosheet. This inverted approach creates a direct electrical pathway while maintaining structural integrity.

Inventive Principle:

Principle #13The other way round (Inversion)

2Reliability

If source-drain material is removed to expose nanosheet material for direct contact, then contact resistance is reduced and carrier injection is enhanced, but manufacturing complexity increases

Engineering Contradiction:

Improvecarrier injection efficiencyVSAvoidcontact formation process complexity

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent performs preliminary etching of the source-drain material to expose the nanosheet before forming the metal contact. This preliminary action creates the necessary interface structure in advance, enabling direct carrier injection without requiring complex post-contact modifications.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent introduces epitaxial silicon as an intermediary layer formed on the exposed nanosheet. This intermediary layer serves as a stable interface that facilitates both direct electrical contact with the nanosheet and subsequent metal contact formation, simplifying the overall manufacturing process.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Reliability

If epitaxial contact layers are formed with higher germanium and boron content than source-drain material, then contact resistance is reduced, but material composition control complexity increases

Engineering Contradiction:

Improvecontact resistanceVSAvoidmaterial composition control

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The patent applies local quality by forming epitaxial contact layers with higher germanium and boron content specifically at the contact region, while maintaining the original source-drain material composition elsewhere. This localized enhancement of material properties reduces contact resistance without requiring uniform composition changes throughout the entire structure.

Inventive Principle:

Principle #3Local quality

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

The method enhances carrier injection and reduces contact resistance by allowing a more direct interface between the metal contact and nanosheets, improving device performance.

Implementation Method 1

removing the source-drain material using a plasma-based process that uses hydrogen and chlorine

Methodology Applied

Scientific EffectPlasma etching: Plasma

Implementation Method 2

forming epitaxial contact layers on the source-drain material and the exposed portion of the nanosheet material

Methodology Applied

Scientific EffectEpitaxial growth: Epitaxy

Data Source

PatentUS20260082667A1Deep Contact with Nanosheet Interface

Publication Date: 2026.03.19 APPLIED MATERIALS INC

AI summary

A method for forming a contact for a source-drain of a gate all around structure incorporates exposing at least a portion of a nanosheet during formation of the contact. A method may include removing a source-drain material to form an exposed portion of a nanosheet material of at least one nanosheet, forming epitaxial contact layers on the source-drain material and the exposed portion of the nanosheet material, forming a silicide contact layer on at least the epitaxial contact layers, and forming a contact with a metal material on the silicide contact layer. In some embodiments, an exposed portion of the nanosheet material comprises an entire end of at least one nanosheet alone or in conjunction with at least a portion of another nanosheet or in conjunction with an entire end of at least one other nanosheet.