Photocleavable Photoresist Underlayer for EUV Pattern Collapse Control
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Solution Overview
Problem
As semiconductor devices continue to shrink, the process windows for photolithographic processing have become increasingly tight, necessitating advancements in photolithographic technologies to maintain design criteria and prevent issues like pattern collapse and pattern scum during extreme ultraviolet lithography.
Innovation Solution
The use of a resist underlayer composition with photocleavable functional groups that adjust the glass transition temperature, density, and porosity upon exposure to actinic radiation, improving adhesion and preventing pattern collapse while maintaining resolution, involves embedding these groups in the polymer backbone, side chains, or cross-linkers, and controlling their amount and molecular weight.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If photolithographic processing is used for patterning, then semiconductor devices can be manufactured, but process windows become tighter as device size decreases
Solution Approach 1:
The patent modifies the chemical and physical properties of the underlayer material by incorporating photocleavable functional groups and adjusting molecular weight. These parameter changes enable the underlayer to undergo controlled modifications during photolithographic processing, improving adhesion and preventing pattern collapse while maintaining adequate process windows even as device dimensions shrink
Solution Approach 2:
The underlayer is formulated as a composite material containing polymer backbone, side chains with photocleavable functional groups, and cross-linkers. This composite structure provides both the mechanical stability needed for small device features and the photo-responsive properties required for precise patterning, effectively resolving the contradiction between miniaturization and manufacturing precision
2Length of moving object
If device size is reduced to meet consumer demand, then device miniaturization is achieved, but pattern collapse and pattern scum occur
Solution Approach 1:
The underlayer is pre-engineered with photocleavable functional groups that will undergo specific chemical changes upon exposure to actinic radiation. This preliminary preparation allows the underlayer to actively counteract pattern collapse and scum formation during processing by controlling adhesion properties in real-time, thereby maintaining pattern integrity despite reduced device dimensions
Solution Approach 2:
The underlayer's adhesion properties are made dynamic through the incorporation of photo-responsive functional groups. During photolithographic processing, the underlayer transitions from a stable state to a modified state in response to actinic radiation, enabling adaptive control of pattern adhesion that prevents collapse and scum while supporting continued device miniaturization
3Manufacturing precision
If photolithographic process window is tightened, then resolution must be improved, but manufacturing complexity increases
Solution Approach 1:
Rather than increasing process complexity, the patent achieves improved resolution by changing the material parameters of the underlayer itself. The incorporation of photocleavable functional groups and optimization of molecular weight provide inherent photo-responsiveness and adhesion control, allowing high-resolution patterning through material properties rather than process complexity
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 enhances the contrast between exposed and unexposed areas, reducing pattern collapse and scum, thereby achieving higher semiconductor device feature resolution and density with reduced defects and improved wafer exposure throughput.
Implementation Method 1
The selectively exposing the photoresist to actinic radiation cleaves the photocleavable functional group in the underlayer
Implementation Method 2
adjust the glass transition temperature, density, and porosity upon exposure to actinic radiation
Data Source
AI summary
A method of manufacturing a semiconductor device includes forming a photoresist underlayer over a semiconductor substrate. The underlayer includes a polymer having a photocleavable functional group. A photoresist layer is formed over the underlayer. The photoresist layer is selectively exposed to actinic radiation, and the selectively exposed photoresist layer is developed to form a photoresist pattern.