Recess Structure Etching with Deep-UV Catalytic Shape Control
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Solution Overview
Problem
Existing microfabrication techniques, such as reactive ion etching (RIE), struggle to form recess structures with complex shapes, particularly those that are inclined or curved, due to uneven etching rates and mask material alteration.
Innovation Solution
A method involving the use of a catalytic material with a polar functional group and deep ultraviolet light irradiation, combined with a fluorine-containing gas at 80°C or higher, to selectively etch a predetermined area on a substrate, forming a recess structure with a controlled shape and uniform width.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If RIE method is used to etch recess structure, then etching efficiency is improved, but etching uniformity deteriorates (wider near opening, narrower at bottom)
Solution Approach 1:
The patent applies asymmetry by tilting the irradiation light at a specific angle (10-70 degrees) relative to the normal of the first surface. This asymmetric illumination creates non-uniform catalytic activity across the mask material surface, with higher activity on the illuminated side and lower activity on the shaded side. This asymmetric catalytic distribution compensates for the natural etching gradient in RIE, achieving uniform width recess structures despite the inherent asymmetry in ion bombardment patterns.
Solution Approach 2:
The patent changes multiple parameters simultaneously: introduces deep ultraviolet light irradiation as a new parameter, adjusts irradiation angle (10-70 degrees), controls irradiation intensity, and sets specific temperature range (80°C or higher). These parameter changes transform the etching mechanism from purely physical/chemical RIE to a photo-catalyzed etching process, enabling precise control over etching uniformity while maintaining high efficiency.
2Shape
If RIE method is used with oblique etching direction, then inclined recess structures can be formed, but mask material shape changes due to simultaneous etching
Solution Approach 1:
The patent introduces deep ultraviolet light as an intermediary that selectively activates the catalytic material only in specific regions. The light acts as a mediator that controls where etching occurs by creating spatially differentiated catalytic activity. This intermediary mechanism allows precise control over etching location and direction, enabling inclined recess structures to be formed while the mask material maintains its intended shape through selective catalytic protection.
Solution Approach 2:
The patent replaces the mechanical/physical RIE process (ion bombardment) with a photo-catalyzed chemical etching process. Instead of relying on physical ion impact that causes mask erosion, the invention uses light-induced catalytic reactions to drive selective etching. This substitution eliminates the harmful mechanical effects on the mask material while achieving the desired inclined recess shape through controlled chemical reactions.
3Ease of manufacture
If conventional RIE is used, then simple recess structures can be formed, but complex curved or inclined shapes are difficult to achieve
Solution Approach 1:
The patent applies dynamics by making the catalytic activity可调 (adjustable) through variable light irradiation parameters. By changing irradiation angle, intensity, and duration, the system can dynamically adapt to create different recess shapes (vertical, inclined, curved). This dynamic control mechanism transforms a static RIE process into a flexible manufacturing system capable of producing diverse complex shapes while maintaining ease of manufacture through a single unified process.
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
Enables the formation of recess structures with precise, inclined or curved shapes by controlling etching rates and maintaining uniformity along the depth direction, overcoming the limitations of traditional RIE methods.
Implementation Method 1
irradiating the catalytic material with irradiation light containing deep ultraviolet light having a wavelength of 380 nm or shorter
Implementation Method 2
irradiation light containing deep ultraviolet light having a wavelength of 380 nm or shorter
Implementation Method 3
exposing the object to be processed to a fluorine-containing gas at 80° C. or higher
Implementation Method 4
a boiling point of a fluoride is 550° C. or lower
Data Source
AI summary
A method comprises a step of placing a catalytic material in a first area on a first surface of an object to be processed, in which: the first surface is made of an element of which a boiling point of a fluoride is 550° C. or lower; the catalytic material contains an organic compound containing a polar functional group, and the catalytic material includes, in a cross-sectional view, a first side surface having a first height H1 and a second side surface having a second height H2, the first and second side surfaces being opposed to each other, in which H1>H2>0 μm; a step of irradiating the catalytic material with irradiation light containing deep ultraviolet light having a wavelength of 380 nm or shorter; and a step of exposing the object to be processed to a fluorine-containing gas at 80° C. or higher.