Electron Beam Depicting for Optical Diffraction Structures
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Solution Overview
Problem
Conventional electron beam depicting methods struggle to achieve a smooth sloped surface and sharp rising edge in diffraction structures for optical elements, particularly in high-precision applications like DVD pickup lenses, due to limitations in beam diameter and control, leading to reduced diffraction efficiency and product value.
Innovation Solution
An electron beam depicting method that involves generating specific input signals for deflecting the electron beam in both main-scanning and sub-scanning directions, with an alternating bias signal adjusted based on the shape data to achieve a smooth sloped surface and sharp edge, using a small-diameter beam while reducing overall patterning time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a small-diameter electron beam is used for high-precision patterning, then manufacturing precision is improved, but patterning time increases
Solution Approach 1:
The patent applies dynamic beam diameter control by varying the electron beam diameter during scanning based on the local pattern requirements. The beam diameter is dynamically adjusted to be small when high precision is needed and large when speed is prioritized, resolving the contradiction between precision and productivity
Solution Approach 2:
The patent changes the beam diameter parameter throughout the patterning process according to the local characteristics of the diffraction structure. By modifying this key parameter spatially and temporally, the system achieves both high precision where needed and high speed where possible
2Productivity
If a large-diameter electron beam is used to reduce patterning time, then productivity is improved, but manufacturing precision deteriorates
Solution Approach 1:
The patent segments the patterning process into different regions with different beam diameter requirements. The scanning area is divided into zones where the beam diameter is optimized locally, allowing large-diameter beam for speed in non-critical areas and small-diameter beam for precision in critical areas
Solution Approach 2:
The patent applies different beam quality (diameter) to different local regions of the pattern. Areas requiring high precision receive small-diameter beams, while areas where speed is more important receive large-diameter beams, optimizing the overall process
3Ease of manufacture
If conventional cutting tools are used to form diffraction structures on metallic molds, then ease of manufacture is improved, but manufacturing precision deteriorates
Solution Approach 1:
The patent replaces mechanical cutting tools with an electron beam system for forming diffraction structures. This substitution eliminates the limitations of mechanical tools while achieving the required submicron precision through non-contact electron beam deposition
4Ease of operation
If laser beam method is used for micrometer-order working, then ease of operation is improved, but manufacturing precision deteriorates for submicron-level work
Solution Approach 1:
The patent changes from optical parameter control (laser) to electron beam parameter control, enabling submicron precision through electron optics. The beam diameter and energy parameters are precisely controlled to achieve the required submicron patterning accuracy
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 creation of optical elements with improved diffraction efficiency and product value by achieving a smooth sloped surface and sharp rising edge, while also reducing patterning time, using a small-diameter electron beam.
Implementation Method 1
an electron beam irradiating section for irradiating the electron beam; an electron beam deflecting section for deflecting the electron beam irradiated from the electron beam irradiating section
Data Source
AI summary
There is described a method for depicting a predetermined pattern, such as a diffraction pattern employed in an optical element, on a substrate. The method includes the steps of: acquiring shape data of the predetermined pattern; generating a first input signal for deflecting an electron beam emitted from an electron gun in a main-scanning direction, and a second input signal for deflecting the electron beam in a sub-scanning direction, based on the shape data of the predetermined pattern; adjusting an alternating bias signal, having a specific frequency, according to the shape data of the predetermined pattern; superposing the alternating bias signal on the second input signal; and deflecting the electron beam emitted from the electron gun in the sub-scanning direction according to the second input signal on which the alternating bias signal is superposed, while scanning the electron beam by deflecting it in a main-scanning direction.