Ion Beam Etching for Fine Pattern Formation
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Solution Overview
Problem
The formation of fine patterns in semiconductor devices is hindered by the resolution limitations of photolithography processes, making it difficult to achieve the required pitch for highly integrated devices.
Innovation Solution
An ion beam etching method is employed, where the ion beam is irradiated at a tilt angle relative to the substrate's surface, allowing for selective etching of layers by adjusting the tilt angle based on the materials involved, thereby controlling the etch selectivity and minimizing defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If photolithography process is used to form patterns, then manufacturing process is simple, but pattern pitch cannot be reduced sufficiently due to resolution limitation
Solution Approach 1:
The patent replaces the photolithography process (optical system) with an ion beam etching process (mechanical/physical system). The ion beam directly physically removes material to form patterns, bypassing the optical resolution limitations of photolithography. This substitution enables finer pattern pitch to be achieved through direct physical etching rather than optical projection.
Solution Approach 2:
The patent utilizes changes in etching parameters, specifically the tilt angle of the ion beam, to control the etching process. By adjusting the tilt angle, the ion beam can selectively etch different materials (mask pattern vs. lower layer) based on their etch selectivity, enabling precise pattern formation with fine pitch that cannot be achieved through photolithography alone.
2Reliability
If ion beam is irradiated perpendicular to substrate surface, then etching is straightforward, but direct irradiation damages sidewalls of mask pattern
Solution Approach 1:
The patent introduces asymmetry in the ion beam irradiation by tilting the beam at a specific angle relative to the substrate surface normal. This asymmetric irradiation geometry causes the ion beam to primarily etch the lower layer material while minimizing direct irradiation and damage to the mask pattern sidewalls, thereby preserving mask integrity during the etching process.
Solution Approach 2:
The tilted ion beam irradiation creates local differences in etching conditions. The mask pattern regions receive reduced direct ion beam exposure compared to the lower layer regions, creating localized protection for the mask while enabling effective etching of the underlying layer. This local quality differentiation protects critical structures while achieving the desired 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 method enables precise control over the etching process, reducing defects and allowing for the formation of patterns with minimized direct irradiation on sidewalls, thus facilitating the creation of fine patterns with reduced pitch.
Implementation Method 1
performing an etching process using an ion beam on the substrate. The ion beam may be irradiated in parallel to a plane defined by the first direction and a direction perpendicular to the top surface of the substrate and may be irradiated at a tilt angle with respect to the top surface of the substrate
Data Source
AI summary
A method of forming a pattern includes forming a lower layer on a substrate, forming a mask pattern on the lower layer, the mask pattern extending in a first direction parallel to a top surface of the substrate, and performing an etching process using an ion beam on the substrate, such that the ion beam is irradiated in parallel to a plane defined by the first direction and a direction perpendicular to the top surface of the substrate, and is irradiated at a tilt angle with respect to the top surface of the substrate, wherein performing the etching process includes adjusting the tilt angle of the ion beam to selectively etch the lower layer or the mask pattern.