Plasma Etching Method for Contact Hole Bowing Prevention
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Solution Overview
Problem
Conventional plasma etching techniques for semiconductor manufacturing often result in bowing effects during the formation of contact holes, especially when using amorphous carbon as a mask, leading to shape errors and precision issues as hole diameters decrease below 0.8 μm.
Innovation Solution
A plasma etching method involving a three-step process: first organic film etching, plasma treatment of the Si-containing and organic films with a rare gas, and second organic film etching, which helps prevent bowing by forming a SiC protection film on the side walls of the holes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If amorphous carbon is used as a mask for plasma etching contact holes, then the etching process can be performed, but a bowing effect occurs where the side wall shape curves outwardly
Solution Approach 1:
A Si-containing film is formed on the side walls of the contact holes before the plasma etching process. This preliminary action creates a protective layer that prevents the bowing effect from occurring during etching, thereby maintaining straight side walls and improving hole shape accuracy
Solution Approach 2:
The invention uses a composite structure consisting of amorphous carbon mask layer combined with a Si-containing protective film. This composite material approach allows the carbon to provide etching selectivity while the Si-containing film prevents side wall bowing, resolving the shape distortion problem
2Length of moving object
If the contact hole diameter is reduced below 0.8 μm for miniaturization, then circuit density increases, but the bowing effect becomes more noticeable
Solution Approach 1:
The Si-containing film is deposited on the substrate before forming the contact holes and performing plasma etching. This preliminary protective layer is crucial for maintaining straight side walls in miniaturized holes below 0.8 μm, where the bowing effect would otherwise be pronounced
Solution Approach 2:
The invention changes the physical and chemical parameters of the etching environment by introducing a Si-containing film that modifies the plasma interaction with the hole walls, thereby preventing bowing even at reduced hole diameters required for circuit miniaturization
3Device complexity
If a single-step organic film etching is performed, then the process is simple, but the bowing effect occurs and shape errors arise
Solution Approach 1:
The Si-containing film is formed as a preliminary protective layer before the organic film etching process. This allows the use of a relatively simple single-step or two-step etching process while still achieving accurate hole shapes without bowing, as the protection is provided by the pre-formed Si-containing film rather than complex etching control
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 method effectively suppresses bowing effects and enables more precise etching with improved anisotropy, maintaining hole shape accuracy even at smaller diameters.
Implementation Method 1
a treatment step of exposing the Si-containing film and the organic film to plasma of a rare gas after the first organic film etching step
Implementation Method 2
forming a SiC protection film on the side walls of the holes
Implementation Method 3
plasma etching method of plasma-etching a subject substrate including at least a film to be etched, an organic film to become a mask of the to-be-etched film, and a Si-containing film
Data Source
AI summary
A plasma etching method, for plasma-etching a target substrate including at least a film to be etched, an organic film to become a mask of the to-be-etched film, and a Si-containing film which are stacked in order from bottom, includes the first organic film etching step, the treatment step and the second organic film etching step when the organic film is etched to form a mask pattern of the to-be-etched film. In the first organic film etching step, a portion of the organic film is etched. In the treatment step, the Si-containing film and the organic film are exposed to plasma of a rare gas after the first organic film etching step. In the second organic film etching step, the remaining portion of the organic film is etched after the treatment step.