Backside Source/Drain Contact Structure With Placeholder Position Margin

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Conventional nanosheet transistor processes face challenges in controlling the levels of backside source/drain contact placeholder structures, leading to risks of damaging the source/drain region and high on-resistance due to improper placement or absence of dielectric isolation layers.

Innovation Solution

The semiconductor structure incorporates dielectric confinement structures, including lower inner spacers and a semiconductor pedestal, around the backside source/drain contact placeholder structure to mitigate damage and high on-resistance during placeholder replacement.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If conventional nanosheet transistor processes are used without dielectric confinement structures, then the manufacturing process is simpler, but the placeholder position control is poor leading to source/drain region damage and high on-resistance

Engineering Contradiction:

Improveplaceholder position controlVSAvoidstructure complexity

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The dielectric isolation structure is segmented into multiple components: lower inner spacers positioned at the bottom, middle inner spacers in the intermediate region, and upper inner spacers at the top. This segmentation allows each component to independently contribute to placeholder position control, providing better manufacturing precision while maintaining manageable structural complexity through modular design.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The dielectric confinement structures including lower inner spacers, middle inner spacers, and upper inner spacers are formed in advance before the placeholder replacement process. This preliminary action establishes the confinement framework that guides and protects the placeholder positioning, preventing damage to source/drain regions and ensuring proper electrical isolation before the actual contact formation occurs.

Inventive Principle:

Principle #10Preliminary action

2Reliability

If dielectric isolation layers are improperly placed or absent, then the device structure is simpler, but source/drain region damage and high on-resistance occur

Engineering Contradiction:

Improvesource/drain region protectionVSAvoidisolation structure complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The dielectric confinement structures serve as protective cushioning elements positioned beforehand around the placeholder region. The lower inner spacers, middle inner spacers, and upper inner spacers create a protective framework that prevents direct contact between the placeholder and sensitive source/drain regions, cushioning against potential damage during placeholder replacement and ensuring reliable electrical isolation.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

Solution Approach 2:

The dielectric confinement structures act as intermediary elements between the placeholder and the source/drain regions. These structures mediate the interaction by providing electrical isolation and physical separation, preventing direct harmful contact while allowing the placeholder to be positioned and replaced safely without compromising source/drain region integrity.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Manufacturing precision

If the backside source/drain contact placeholder structure level is not controlled, then the manufacturing process is simpler, but placeholder replacement causes damage or high on-resistance

Engineering Contradiction:

Improveplaceholder level controlVSAvoidprocess complexity

Core Design Contradiction:

Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The dielectric confinement structures enable precise control of the placeholder level parameter through their geometric configuration. The lower inner spacers, middle inner spacers, and upper inner spacers are designed with specific heights and positions that define the acceptable placeholder level range, transforming the uncontrolled placeholder placement into a precisely controlled parameter that ensures proper electrical connection without damage.

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS12588265B2Semiconductor structure with enhanced placeholder position margin

Publication Date: 2026.03.24 INTERNATIONAL BUSINESS MACHINE CORPORATION

AI summary

A semiconductor structure having improved placeholder position margin is provided. The semiconductor structure includes a backside source/drain contact structure contacting one source/drain region of a nanosheet transistor. The backside source/drain contact structure has a first portion and a second portion. The second portion of the backside source/drain contact structure, which is in direct contact with the source/drain region is confined by bottommost upper inner spacers, lower inner spacers and a semiconductor pedestal which vertically separates the bottommost inner spacers from the lower inner spacers.