SOI Deflecting Plate Apertures for Uniform Electron Beam Deflection
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Solution Overview
Problem
Conventional methods for fabricating deflecting plates in electron beam lithography face challenges such as wafer cracks, bonding failures, and poor uniformity in the vertical length of apertures due to thinning processes and isotropic etching, which affect the precision and reliability of electron beam deflection.
Innovation Solution
The use of a silicon-on-insulator (SOI) substrate, where the device layer and insulator layer are pre-fabricated with a large thickness, allowing for the formation of vertically extending apertures without thinning and bonding through the insulator layer, ensuring uniformity and avoiding etching through the device layer, thus improving aperture uniformity and reducing the risk of cracks and bonding failures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional thinning processes are used to fabricate deflecting plates, then the apertures can be formed, but wafer cracks occur and uniformity in vertical length of apertures deteriorates
Solution Approach 1:
The patent applies preliminary action by pre-fabricating the deflecting plate with apertures having uniform vertical length before the thinning process. The apertures are formed through the entire thickness of the device layer down to the insulator layer, ensuring uniformity is established before any thinning operations that could cause cracks or non-uniformity.
Solution Approach 2:
The patent extracts the problematic thinning process from the aperture formation sequence. By forming apertures through the full thickness first and then selectively removing only the necessary portions, the method avoids the harmful effects of thinning on already-formed apertures, preventing both cracks and uniformity issues.
2Ease of manufacture
If bonding processes are used in conventional fabrication, then the deflecting plate can be assembled, but bonding failures occur
Solution Approach 1:
The patent extracts and eliminates the bonding process from the fabrication sequence by using a monolithic SOI substrate structure. The device layer is directly formed on the insulator layer without requiring separate bonding steps, thereby removing the source of bonding failures while maintaining ease of manufacture through simplified processing.
3Ease of manufacture
If isotropic etching is used to form apertures, then the etching process is simple, but poor uniformity in vertical length of apertures results
Solution Approach 1:
The patent applies local quality by using anisotropic etching that selectively removes material in specific directions. The etching process is tailored to remove material vertically through the device layer while preserving lateral dimensions, creating apertures with uniform vertical length that would not be achievable with isotropic etching.
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 uniformity and precision of electron beam deflection, reducing the risk of wafer cracks and bonding failures, leading to improved performance and reliability in electron beam lithography systems.
Implementation Method 1
a plurality of electron beams pass through the plurality of deflecting apertures during an EBL process
Data Source
AI summary
A deflecting plate includes a silicon-on-insulator (SOI) substrate. The SOI substrate includes: an insulator layer having a top surface and a bottom surface; a device layer coupled to the insulator layer at the top surface, wherein multiple deflecting apertures are disposed in the device layer, each of which extending from a top open end to a bottom open end through the device layer, and wherein the bottom open end is coplanar with the top surface of the insulator layer; and a handle substrate coupled to the insulator layer at the bottom surface, wherein a cavity is disposed in the handle substrate and extends from a cavity open end to a cavity bottom wall, and wherein the bottom wall is coplanar with the top surface of the insulator layer, such that the bottom open end of each deflecting aperture is exposed to the cavity.