Plasma Etching Sequence for Metal Mask Deposit Control
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Solution Overview
Problem
Existing etching methods using plasma generated from mixed gases like WF6 and C4F8 struggle to effectively form and modify metal-containing deposits on masks during the etching process, leading to inefficiencies in controlling the etching process and the resulting film profiles.
Innovation Solution
A method involving the formation of a metal-containing deposit on a mask using a first plasma from a metal-containing and hydrogen-containing gas, followed by modification using a second plasma from a different gas, and subsequent etching of the target film using a third plasma, allowing for precise control over the deposit's shape and composition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If plasma generated from mixed gas of WF6 and C4F8 is used for etching, then etching can be performed, but the ability to form and modify metal-containing deposits on the mask is insufficient
Solution Approach 1:
The etching process is divided into multiple sequential steps, each using a different plasma processing gas with specific functions: first processing gas (WF6+H2) for forming metal-containing deposits, second processing gas (CF4+H2) for modifying the deposits, and third processing gas (CHF3) for etching the target film. This segmentation allows each step to be optimized independently for its specific purpose.
Solution Approach 2:
The invention changes the chemical composition parameters of the plasma processing gas between steps. The first gas mixture (WF6 and H2) provides metal supply, the second gas mixture (CF4 and H2) provides carbon and fluorine for modification, and the third gas (CHF3) provides etching capability. This parameter change enables different functional outcomes at different stages.
2Manufacturing precision
If a single plasma processing gas is used for etching, then the process is simple, but the precision in controlling deposit shape and composition is insufficient
Solution Approach 1:
The single-step etching process is segmented into three distinct plasma processing steps, each with a dedicated gas mixture optimized for its specific function: deposit formation, deposit modification, and film etching. This segmentation achieves precise control over deposit characteristics.
Solution Approach 2:
The metal-containing deposits are formed and modified on the mask before the actual etching of the target film begins. This preliminary action prepares the mask with optimized deposits that will define the etching pattern, separating the deposit preparation from the etching operation itself.
3Manufacturing precision
If metal-containing deposits are formed during etching, then mask definition is improved, but the process time increases
Solution Approach 1:
The metal-containing deposits are formed as a preliminary step before the main etching operation. By preparing the deposits in advance with optimized parameters (using WF6 and H2 plasma), the subsequent etching step can proceed efficiently without needing to form deposits during the etching process itself.
Solution Approach 2:
The invention optimizes the parameters of each plasma processing step to minimize time: the first step uses conditions optimized for rapid deposit formation, the second step uses conditions for quick modification, and the third step uses conditions for efficient etching. This parameter optimization reduces the total process time while maintaining precision.
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 enables the formation of metal-containing deposits with desired shapes and characteristics, facilitating controlled etching and improved film profiles, enhancing the precision and efficiency of the etching process.
Implementation Method 1
forming a metal-containing deposit on the mask by a first plasma generated from a first processing gas including a metal-containing gas and a hydrogen-containing gas
Implementation Method 2
deforming or modifying the metal-containing deposit by a second plasma generated from a second processing gas different from the first processing gas
Implementation Method 3
etching the etching target film by a third plasma generated from a third processing gas different from the first and second processing gases
Data Source
AI summary
An etching method includes: (a) providing a substrate including an etching target film and a mask on the etching target film; (b) after (a), forming a metal-containing deposit on the mask by a first plasma generated from a first processing gas including a metal-containing gas and a hydrogen-containing gas; (c) after (b), deforming or modifying the metal-containing deposit by a second plasma generated from a second processing gas different from the first processing gas; and (d) after (c), etching the etching target film.