Selective Ion Implantation Etching for Thin Resist Pattern Transfer
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Solution Overview
Problem
As feature sizes in semiconductor manufacturing decrease, the stability of mask features decreases, leading to pattern defects such as photoresist line or pillar collapse, and thinner resist films face excessive damage or etching, necessitating improved etching processes with higher selectivity to maintain pattern integrity.
Innovation Solution
A two-step etching process involving selective modification with lightweight ions, such as hydrogen ions, followed by chemical etching with a halogen-containing etchant gas, to enhance the selectivity of the etching process, minimizing damage to the resist layer and ensuring precise etching of the underlying material.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the thickness of photoresist film is reduced to maintain aspect ratio, then mask feature stability improves, but resist retention during etching deteriorates
Solution Approach 1:
The patent applies preliminary action by performing a pre-etch treatment on the underlying material before the main etching process. This pre-treatment modifies the material properties at the etch interface, enabling selective etching that spares the thin photoresist film. The pre-etch step creates a modified region that is more susceptible to etching, allowing the main etch to proceed without damaging the resist
Solution Approach 2:
The patent employs parameter changes by altering the chemical composition and physical properties of the underlying material through the pre-etch treatment. This changes the etch selectivity parameters, creating a differential etch rate between the modified region and the photoresist. The parameter change enables the etch process to distinguish between material that should be removed and material that should be protected
2Productivity
If conventional etching processes are used, then etching speed is maintained, but resist damage increases
Solution Approach 1:
The patent applies segmentation by dividing the etching process into two distinct segments: a pre-etch treatment step and a main etching step. The pre-etch segment prepares the underlying material by modifying its properties, while the main etch segment performs the actual material removal. This segmentation allows each step to be optimized independently - the pre-etch for selectivity and the main etch for speed - thereby maintaining high etching speed while minimizing resist damage
Solution Approach 2:
The pre-etch treatment acts as an intermediary that mediates between the etchant and the photoresist film. By modifying the underlying material properties before the main etch, it creates a protective interface that prevents direct harmful interaction between the aggressive etchant and the thin photoresist. This intermediary step enables fast etching while shielding the resist from damage
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 process achieves improved resist retention and etch selectivity, allowing for thinner resist layers to be used effectively, reducing defects and maintaining precise pattern transfer in semiconductor fabrication.
Implementation Method 1
selectively modifying the underlying material using hydrogen ions to form a modified region of the underlying material
Implementation Method 2
exciting a plasma that has hydrogen ions, and exposing both a patterned resist layer and the underlying material of a substrate in a plasma etching chamber to the hydrogen ions
Implementation Method 3
chemically etching the modified region using a halogen-containing etchant gas
Data Source
AI summary
A method of chemically etching an underlying material includes selectively modifying the underlying material (e.g., a silicon-containing material, like silicon carbide) using lightweight ions (e.g., hydrogen ions, helium ions, etc.) to form a modified region of the underlying material and chemically etching the modified region using a halogen-containing etchant gas (e.g., a fluorine-containing gas, like sulfur hexafluoride). The underlying material is exposed through openings in a resist layer, which may contain carbon and/or a metal, such as a chemically amplified resist or a metal oxide resist. The selective modification step may implant the lightweight ions into the underlying material. Plasma may be used during one or both of the selective modification step and the chemical etching step. Bias power may be applied during the selective modification step and may be higher than bias power applied during the chemical etching step, which may be zero.