Multi-Layer Mask Bottom Layer Chemical Treatment for Planarization
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Solution Overview
Problem
The manufacturing of integrated circuits faces challenges in controlling critical dimensions, particularly in forming a flat and uniform multi-layer mask for semiconductor devices, which affects the precision and uniformity of photolithography processes.
Innovation Solution
A method involving the formation of a multi-layer mask with a bottom layer treated using a chemical process to induce crosslinks, followed by a sacrificial layer and chemical mechanical polishing (CMP) to achieve a planarized surface, allowing for the formation of a stable photoresist layer with improved flatness and selectivity, enabling precise etching and pattern transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a multi-layer mask is formed without chemical treatment, then the formation process is simpler, but the flatness and uniformity of the photoresist layer deteriorate
Solution Approach 1:
The patent applies preliminary chemical treatment to the bottom layer before forming the photoresist layer. This treatment modifies the surface properties of the bottom layer in advance, ensuring that subsequent layers can be formed with the required flatness and uniformity. The chemical treatment creates a prepared surface that facilitates better adhesion and flatter photoresist formation.
Solution Approach 2:
The patent introduces a multi-layer structure with different materials (bottom layer, middle layer, photoresist layer) where each layer has specific local properties optimized for its function. The bottom layer undergoes chemical treatment to provide specific surface characteristics, while the middle layer provides structural support, and the photoresist layer provides patterning capability. This local differentiation of material properties resolves the contradiction between process simplicity and photoresist flatness.
2Manufacturing precision
If CMP process is applied to achieve planarized surface, then the flatness of photoresist layer is improved, but underlying structures may be damaged by over-polishing
Solution Approach 1:
The patent changes the material composition and surface properties of the bottom layer through chemical treatment, which modifies its removal rate characteristics during CMP. This parameter change allows the bottom layer to serve as a protective layer that polishes at a controlled rate, preventing over-polishing damage to underlying structures while still achieving the required flatness for the photoresist layer.
Solution Approach 2:
The chemically treated bottom layer acts as a cushioning layer before the actual photoresist formation. This layer is designed to be removed at a controlled rate during CMP, providing a buffer that protects the underlying structures from over-polishing while ensuring the photoresist layer can be formed on a sufficiently planar surface.
3Reliability
If chemical treatment is applied to induce crosslinks, then selectivity and stability of the mask structure is improved, but the process complexity increases
Solution Approach 1:
The patent applies chemical treatment to change the chemical and physical parameters of the bottom layer, inducing crosslinks that enhance the stability and selectivity of the mask structure. This parameter change in the material properties provides better adhesion and structural integrity, justifying the additional process step.
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 flatness of the photoresist layer, improves critical dimension uniformity, and prevents damage to underlying structures by allowing controlled CMP processes, resulting in improved focus budget and reduced risk of over-polishing.
Implementation Method 1
performing a chemical treatment to treat an upper portion of the bottom layer, while leaving a lower portion of the bottom layer untreated
Implementation Method 2
performing a chemical mechanical polish (CMP) process on the sacrificial layer, wherein the treated upper portion of the bottom layer of the multi-layer mask has a slower removal rate in the CMP process than that of the untreated lower portion of the bottom layer
Data Source
AI summary
A method includes forming a bottom layer of a multi-layer mask over a first gate structure extending across a fin; performing a chemical treatment to treat an upper portion of the bottom layer of the multi-layer mask, while leaving a lower portion of the bottom layer of the multi-layer mask untreated; forming a sacrificial layer over the bottom layer of the multi-layer mask; performing a polish process on the sacrificial layer, in which the treated upper portion of the bottom layer of the multi-layer mask has a slower removal rate in the polish process than that of the untreated lower portion of the bottom layer of the multi-layer mask; forming middle and top layers of the multi-layer mask; patterning the multi-layer mask; and etching an exposed portion of the first gate structure to break the first gate structure into a plurality of second gate structures.