Photosensitive Middle Layer for Lithographic Tri-Layer Uniformity
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Solution Overview
Problem
Lithographic tri-layer structures in semiconductor manufacturing face challenges with non-uniform light absorption in the photosensitive top layer, leading to irregularities such as footing or undercut in pattern profiles, which affect subsequent processing steps.
Innovation Solution
Incorporating photo-responsive compositions (PRCs) immobilized on the top surface of the middle layer provides additional sites for photochemical reactions, ensuring uniform photochemical changes and preserving the proper profile of the final pattern by extending photosensitive moieties across the interface between the middle and photoresist layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a photosensitive top layer is used in lithographic tri-layer structures, then photolithography patterning capability is provided, but non-uniform light absorption occurs leading to irregular pattern profiles
Solution Approach 1:
The patent applies local quality by incorporating photosensitive moieties at specific locations within the middle layer structure. These moieties are positioned to absorb light and generate acid or base species precisely where needed, creating localized chemical changes that compensate for the non-uniform light absorption in the photoresist layer and produce uniform pattern profiles throughout the structure.
Solution Approach 2:
The middle layer acts as an intermediary between the photoresist top layer and the underlying bottom layer. By embedding photosensitive moieties in the middle layer, the system creates an intermediate mechanism for light absorption and chemical generation that mediates the exposure process, ensuring uniform photochemical changes across the pattern depth and enabling precise pattern transfer.
2Productivity
If traditional tri-layer structures are used, then basic patterning is achieved, but pattern profile control is insufficient leading to footing or undercut irregularities
Solution Approach 1:
The patent changes the chemical and physical parameters of the middle layer by incorporating photosensitive moieties with specific light absorption characteristics and acid/base generation properties. This parameter modification enables the middle layer to actively participate in the photochemical reaction, generating species that diffuse into the photoresist to uniformize the exposure and eliminate profile irregularities like footing and undercut.
Solution Approach 2:
The middle layer is designed as a composite material combining a base polymer matrix with embedded photosensitive moieties. This composite structure provides both the mechanical integrity needed for pattern transfer and the photosensitive functionality required for uniform light absorption and chemical generation, thereby improving pattern profile control while maintaining patterning efficiency.
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 ensures uniform line widths and remedies pattern irregularities like footing and undercut, enhancing the control over pattern profiles and subsequent processing steps in semiconductor device manufacturing.
Implementation Method 1
The middle layer includes a photosensitive moiety that produces an acid or a base in response to light
Data Source
AI summary
A method includes providing a substrate; forming a bottom layer over the substrate; forming a middle layer over the bottom layer, a top surface of which including a photosensitive moiety having a first end anchored in the middle layer and a second end extending away from the top surface of the middle layer; forming a photoresist layer over the middle layer; exposing the photoresist layer to a radiation source; and developing the photoresist layer to form a pattern. The photosensitive moiety, which includes one of a photo-acid generator (PAG), a photo-base generator (PBG), photo-decomposable base (PDB), or photo-decomposable quencher (PDQ), may be anchored to a polymer backbone forming the middle layer via one or more linker groups. A distance by which the photosensitive moiety extends into the photoresist layer may be determined by a length of the linker group.