DRIE Sidewall Scalloping Control via Auxiliary Mask
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current pattern-forming methods using deep reactive ion etching (DRIE) often result in upper pattern portions that do not protrude or scarcely do, with scallops on the sidewalls being irregular, leading to voids and potential device failures due to undercut formation during the etching process.
Innovation Solution
A method involving the formation of a mask pattern on a substrate, followed by DRIE with an auxiliary mask pattern on the sidewall, and subsequent partial removal of the mask pattern through isotropic etching to expose the upper surface, allowing for anisotropic etching to smooth the scallops and prevent protrusions, thereby ensuring a conformal material layer can be formed on the patterned surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If deep reactive ion etching (DRIE) is used to form patterns, then etching depth and precision are improved, but scallops on sidewalls become irregular and protrusions occur
Solution Approach 1:
An auxiliary mask pattern is introduced as an intermediary element on the sidewall of the mask pattern. This auxiliary mask serves as a mediator that prevents the formation of irregular scallops and protrusions during DRIE by controlling the etching process at critical locations, thereby maintaining sidewall smoothness while preserving etching precision.
Solution Approach 2:
The auxiliary mask pattern is formed on the sidewall before the DRIE process begins. This preliminary action prepares the sidewall surface in advance to prevent the formation of irregular scallops and protrusions during etching, ensuring smooth sidewalls from the outset rather than requiring post-processing correction.
2Ease of manufacture
If mask pattern is completely removed after DRIE, then pattern transfer is complete, but upper pattern portions do not protrude and voids form
Solution Approach 1:
Instead of completely removing the mask pattern, only a partial removal is performed to expose a portion of the upper surface of the substrate. This partial action is sufficient to prevent void formation and ensure proper material layer deposition, while avoiding the excessive removal that would cause upper pattern portions to not protrude and create profiling issues.
3Ease of manufacture
If conformal material layer is formed on irregular patterned surface, then coverage is achieved, but voids and defects occur
Solution Approach 1:
The auxiliary mask pattern is formed preliminarily on the sidewall before material layer deposition. This preliminary structure ensures that the surface is properly prepared and protected, allowing conformal material layer deposition to proceed without forming voids or defects, thereby ensuring both ease of manufacture and device reliability.
Solution Approach 2:
The auxiliary mask pattern acts as an intermediary protective structure during material layer deposition. It prevents direct contact between the deposition process and vulnerable areas, ensuring uniform and defect-free material coverage while maintaining the integrity of the underlying pattern structure.
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 effectively prevents protrusions and voids, enabling the formation of smooth sidewall scallops and ensuring a conformal material layer on the substrate, enhancing the precision and reliability of pattern formation for fine electronic devices.
Implementation Method 1
The partial removal of the mask pattern to expose the portion of the upper surface of the substrate may be performed by isotropic etching
Implementation Method 2
etching the substrate by deep reactive ion etching (DRIE)
Implementation Method 3
forming a protective layer on a surface produced by the isotropic etching
Data Source
AI summary
A method of forming a pattern includes forming a mask pattern on a substrate; etching the substrate by deep reactive ion etching (DRIE) and by using the mask pattern as an etch mask; partially removing the mask pattern to expose a portion of an upper surface of the substrate; and etching the exposed portion of the upper surface of the substrate. In the method, when a pattern is formed by DRIE, an upper portion of the pattern does not protrude or scarcely protrudes, and scallops of a sidewall of the pattern are smooth, and thus a conformal material layer may be easily formed on a surface of the pattern.