Backside Power Delivery Fabrication Using Laser Liftoff Layers

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Existing semiconductor fabrication methods that use chemical-mechanical polishing to remove carrier substrates can damage transistors and frontside interconnect structures, necessitating a more gentle and effective method for substrate removal.

Innovation Solution

Employing a laser liftoff layer between the stack and the carrier substrate to facilitate radiation-induced removal of the carrier substrate, allowing for the formation of backside power delivery networks without mechanical damage to the transistors or frontside interconnect structures.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If chemical-mechanical polishing is used to remove carrier substrates, then substrate removal is achieved, but transistors and frontside interconnect structures are damaged

Engineering Contradiction:

Improvesubstrate removal efficiencyVSAvoidintegrity of transistors and interconnect structures

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent replaces the mechanical chemical-mechanical polishing process with a laser-based removal process. The laser liftoff layer is irradiated with laser energy to selectively remove the carrier substrate without mechanical contact, thereby eliminating the damage caused by polishing while maintaining substrate removal capability

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent introduces a laser liftoff layer as an intermediary between the carrier substrate and the transistor stack. This intermediate layer absorbs laser energy and facilitates selective removal of the carrier substrate, protecting the underlying transistor structures from direct laser damage while enabling clean substrate removal

Inventive Principle:

Principle #24Intermediary (Mediator)

2Adaptability or versatility

If conventional fabrication methods are used, then manufacturing process is simple, but backside power delivery networks cannot be formed

Engineering Contradiction:

Improvecapability to form backside power delivery networksVSAvoidfabrication process complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent incorporates a laser liftoff layer during the initial stack formation process, before backside access is needed. This preliminary action enables subsequent laser-based carrier substrate removal and backside power delivery network formation without requiring complex process modifications later in fabrication

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent segments the fabrication process into distinct stages: frontside processing, carrier substrate removal via laser liftoff, and backside power delivery network formation. This segmentation allows independent optimization of each stage and enables the formation of backside structures without interfering with frontside components

Inventive Principle:

Principle #1Segmentation

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

Enables the formation of backside power rails on transistors while preserving the integrity of existing structures, enhancing the reliability and efficiency of semiconductor device fabrication.

Implementation Method 1

removing the first substrate by applying radiation on the laser liftoff layer

Methodology Applied

Scientific EffectRadiation absorption: Absorption (EM radiation)

Data Source

PatentUS12575391B2Methods for fabricating semiconductor devices with backside power delivery network using laser liftoff layer

Publication Date: 2026.03.10 TOKYO ELECTRON LTD

AI summary

A method for fabricating semiconductor devices is disclosed. The method includes forming a stack on a first substrate. A laser liftoff layer is interposed between the stack and the first substrate. The method includes forming a plurality of first interconnect structures over a first side of the stack. The method includes attaching a second substrate to the stack on the first side, with the plurality of first interconnect structures interposed between the stack and the second substrate; removing the first substrate by applying radiation on the laser liftoff layer. The method includes forming a plurality of second interconnect structures on a second side of the stack opposite to the first side.