Backside Via Contact Structure for Low-Resistance Source/Drain Access

Solution Overview

Problem

The challenge in highly downscaled integrated circuit (IC) devices is to improve the reliability of the electrical contact between the backside contact structure and the source/drain region in field-effect transistors (FETs) to enhance performance and reliability.

Innovation Solution

The IC device incorporates a backside via contact structure with a semiconductor layer having a dopant concentration gradient, including a bottom epitaxial layer with a higher dopant concentration than the blocking and main epitaxial layers, and a backside metal silicide film to reduce contact resistance and improve electrical reliability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If a backside via contact structure is introduced in highly downscaled IC devices, then device integration and operating speed are improved, but the reliability of electrical contact between the backside contact structure and source/drain region deteriorates

Engineering Contradiction:

Improveoperating speedVSAvoidelectrical contact reliability

Core Design Contradiction:

SpeedVSReliability

Solution Approach 1:

The patent applies local quality by creating a dopant concentration gradient within the source/drain region, where the bottom portion has higher dopant concentration than the upper portion. This localized variation in dopant concentration optimizes the electrical contact properties at the specific location where the backside via contact interfaces with the source/drain region, thereby improving contact reliability without compromising overall device performance

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent changes the dopant concentration parameter within the source/drain region by forming a gradient structure where dopant concentration varies from the bottom to the top of the source/drain region. This parameter change enables the bottom portion to have enhanced electrical conductivity for reliable backside contact while maintaining appropriate electrical characteristics in the upper portion for proper transistor operation

Inventive Principle:

Principle #35Parameter changes

2Productivity

If the source/drain region is highly downscaled, then device density is improved, but contact resistance between the backside via contact and source/drain region increases

Engineering Contradiction:

Improvedevice densityVSAvoidcontact resistance

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent applies local quality by creating a dopant concentration gradient within the source/drain region, where the bottom portion has higher dopant concentration than the upper portion. This localized variation in dopant concentration optimizes the electrical contact properties at the specific location where the backside via contact interfaces with the source/drain region, thereby improving contact reliability without compromising overall device performance

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent changes the dopant concentration parameter within the source/drain region by forming a gradient structure where dopant concentration varies from the bottom to the top of the source/drain region. This parameter change enables the bottom portion to have enhanced electrical conductivity for reliable backside contact while maintaining appropriate electrical characteristics in the upper portion for proper transistor operation

Inventive Principle:

Principle #35Parameter changes

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 solution effectively reduces Schottky barrier height and contact resistance, enhancing the electrical reliability and performance of the IC device by stabilizing the electrical contact between the backside contact structure and the source/drain region.

Implementation Method 1

a first dopant concentration of the bottom epitaxial layer is greater than a second dopant concentration of the blocking epitaxial layer and is greater than or equal to a third dopant concentration of the main epitaxial layer

Methodology Applied

Scientific EffectDopant concentration gradient: Dopants

Implementation Method 2

The solution effectively reduces Schottky barrier height and contact resistance

Methodology Applied

Scientific EffectSchottky barrier reduction:

Data Source

PatentUS20250386539A1Integrated circuit device

Publication Date: 2025.12.18 SAMSUNG ELECTRONICS CO LTD

AI summary

An integrated circuit device includes a channel region, a gate line surrounding the channel region, a source/drain region contacting the channel region, and a backside via contact passing through a portion of the source/drain region in a vertical direction from a back side of the source/drain region. The source/drain region includes a bottom epitaxial layer protruding from a bottom surface of the source/drain region, a blocking epitaxial layer contacting the channel region and the bottom epitaxial layer, and a main epitaxial layer filling a space defined by the blocking epitaxial layer. A first dopant concentration of the bottom epitaxial layer is greater than a second dopant concentration of the blocking epitaxial layer and is greater than or equal to a third dopant concentration of the main epitaxial layer, and the backside via contact passes through at least a portion of the bottom epitaxial layer in the vertical direction.