Semiconductor Mask Pattern Ellipticity Reduction via Dual Etching
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Solution Overview
Problem
In semiconductor device manufacturing, forming fine patterns with small widths and small spaces is challenging, particularly in achieving uniform diameter and reducing ellipticity of openings, which affects the density and performance of semiconductor devices.
Innovation Solution
A method involving the sequential formation of first and second line mask patterns at specific angles, followed by anisotropic and isotropic etching processes to create diamond-shaped etching regions, which reduces ellipticity and shapes openings into circular forms with uniform diameters, allowing for the formation of zigzag-patterned holes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If anisotropic etching is performed to form openings through diamond-shaped etching regions, then the openings are formed with reduced ellipticity, but the openings still exhibit some elliptical shape that affects uniformity
Solution Approach 1:
The patent applies parameter changes by transitioning from anisotropic etching to isotropic etching. The isotropic etching process uses different etching parameters (isotropic conditions) to modify the opening shape, transforming elliptical openings into circular openings with uniform diameters. This parameter change resolves the contradiction by achieving both shape improvement and uniformity enhancement.
2Productivity
If the mask layer is etched to form fine patterns with small widths, then the device density is increased, but the ellipticity of openings increases making uniform diameter formation difficult
Solution Approach 1:
The patent employs continuity of useful action by performing sequential etching processes. First, anisotropic etching forms the initial openings with reduced ellipticity, then isotropic etching continuously acts on these openings to further refine them into circular shapes with uniform diameters. This continuous sequence of useful actions ensures both high device density and opening uniformity are achieved together.
3Shape
If diamond-shaped etching regions are formed by intersecting line mask patterns, then the ellipticity of openings is reduced, but the openings still require additional processing to achieve circular shape with uniform diameter
Solution Approach 1:
The patent applies preliminary action by first forming diamond-shaped etching regions through intersecting line mask patterns, which preliminarily reduces the ellipticity of openings. This preliminary action prepares the openings for the subsequent isotropic etching step, making the final circular shape formation more effective. The preliminary reduction of ellipticity simplifies the overall process by pre-conditioning the openings.
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 enhances the density and performance of semiconductor devices by increasing the diameter of fine patterns and reducing ellipticity, enabling the formation of high-density semiconductor memory devices and variable resistance memory devices with improved contact properties.
Implementation Method 1
anisotropically etching the mask layer exposed by the first and second line mask patterns to form elliptical openings
Implementation Method 2
isotropically etching the mask layer provided with the openings to form a mask pattern with enlarged openings
Data Source
AI summary
A method of forming a fine pattern includes forming first line mask patterns on a mask layer to extend along a direction, forming second line mask patterns to extend along a diagonal direction with respect to the first line mask patterns, anisotropically etching the mask layer exposed by the first and second line mask patterns to form elliptical openings, and isotropically etching the mask layer provided with the openings to form a mask pattern with enlarged openings.