Double Patterning Etching for Semiconductor Pattern Density
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current methods for forming fine patterns in semiconductor devices face limitations due to resolution restrictions of photolithography, particularly when forming patterns at different pitches in regions with varying pattern densities, leading to thickness differences in films to be removed, which can result in undesired pattern shapes.
Innovation Solution
A method involving double patterning with a hardmask layer and buffer layer, where reactive ion etching and inverse reactive ion etching are used to form mask patterns and etch film patterns, controlling the etching ambient conditions to manage polymer by-products and prevent step transfer issues across regions with different pattern densities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If double patterning is used to form patterns at fine pitch overcoming photolithography resolution restrictions, then manufacturing precision is improved, but thickness differences occur in films to be removed across regions with different pattern densities
Solution Approach 1:
The patent applies preliminary action by forming a buffer layer before the main patterning process. This buffer layer is selectively removed in high-density regions through inverse RIE, preparing the surface in advance to prevent step transfer during subsequent etching operations, thereby maintaining film thickness uniformity across regions with different pattern densities.
Solution Approach 2:
The patent implements local quality by using inverse reactive ion etching to remove the buffer layer only in high-density pattern regions, while leaving it intact in low-density regions. This localized modification allows different regions to have different surface conditions tailored to their specific pattern density requirements, preventing thickness differences in the final patterned film.
2Adaptability or versatility
If patterns at different pitches are simultaneously formed in regions with different pattern densities, then adaptability is improved, but different etch rates per region cause desired pattern shapes to be unobtainable
Solution Approach 1:
The patent uses local quality by selectively removing the buffer layer in high-density regions through inverse RIE while preserving it in low-density regions. This creates region-specific surface conditions that compensate for different etch rates, allowing both high-density and low-density regions to achieve their desired pattern shapes simultaneously despite their different pattern densities.
Solution Approach 2:
The patent applies parameter changes by modifying the etching ambient conditions during inverse RIE to control the removal of the buffer layer. By adjusting etching parameters such as gas composition and power, the process selectively removes the buffer layer in high-density regions while maintaining it in low-density regions, enabling accurate pattern formation across diverse regions.
3Device complexity
If conventional single patterning is used, then process simplicity is maintained, but photolithography resolution restrictions prevent formation of patterns at fine pitch
Solution Approach 1:
The patent applies segmentation by dividing the patterning process into multiple stages: first forming initial patterns through photolithography, then using inverse RIE to create additional patterns in high-density regions. This segmentation allows the process to overcome photolithography resolution limits while maintaining reasonable process complexity by targeting only specific regions for additional patterning.
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 effectively prevents step transfer caused by thickness differences, allowing for the formation of fine patterns that overcome photolithography resolution limitations, enabling consistent pattern formation across regions with diverse densities.
Implementation Method 1
first etching by reactive ion etching (RIE) the buffer layer and the hardmask layer both in the first region and the second region under a first etching ambient
Implementation Method 2
accumulating polymer by-products on the first surface of the etch film exposed in the first region under a second etching ambient having polymer by-products produced much greater than in the first etching ambient
Data Source
AI summary
A method of forming fine patterns of a semiconductor device includes double etching by changing a quantity of producing polymer by-products to etch a film with different thicknesses in regions having different pattern densities. In a first etching, reactive ion etching (RIE) is performed upon a buffer layer and a hardmask layer both in a low-density pattern region and a high-density pattern region under a first etching ambient until an etch film is exposed in the low-density pattern region using mask patterns as an etch mask. In second etching for forming the hardmask patterns, using the mask patterns as an etch mask, the hardmask layer is etched until the etch film is exposed in the high-density pattern region while accumulating polymer by-products on the etch film in the low-density pattern region under a second etching ambient having polymer by-products produced greater than in the first etching ambient.