Metal-Shell Etch Mask for High-Aspect-Ratio Selectivity
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing etch masks, particularly those made of nonmetal materials like amorphous carbon, suffer from selectivity limitations during high aspect ratio etching processes, leading to inadequate aspect ratios and integration challenges when transitioning to metal-based masks.
Innovation Solution
A hybrid approach involving a nonmetal etch mask encapsulated with a metal shell deposited using bipolar pulsed magnetron sputtering, which ensures the metal shell is continuous and smooth, enhancing selectivity and adhesion while maintaining patterning benefits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional nonmetal hardmask materials like amorphous carbon are used, then patterning benefits are maintained, but etch selectivity is insufficient for high aspect ratio applications
Solution Approach 1:
The patent employs a composite structure consisting of a nonmetal etch mask layer combined with a metal shell layer. The nonmetal layer provides superior patterning characteristics while the metal shell provides enhanced etch selectivity. This composite material approach allows the system to simultaneously achieve both patterning benefits and high etch selectivity required for high aspect ratio applications.
Solution Approach 2:
The metal shell is deposited directly onto and encapsulates the nonmetal etch mask layer, creating a nested structure where the metal layer surrounds and protects the patterned nonmetal mask. This nesting approach allows the inner nonmetal mask to maintain its patterning function while the outer metal shell provides the necessary etch selectivity barrier.
2Reliability
If metal hardmask materials are used to increase etch selectivity, then etch selectivity improves, but film quality deteriorates with poor adhesion and rough surfaces
Solution Approach 1:
The patent utilizes bipolar pulsed magnetron sputtering to precisely control deposition parameters including pulse duration, power levels, and gas flow rates. By optimizing these parameters, the process achieves smooth film surfaces with excellent adhesion to the underlying nonmetal mask layer, eliminating the typical film quality problems associated with metal mask deposition.
Solution Approach 2:
The bipolar pulsed sputtering process alternates between depositing metal atoms during negative pulses and clearing the plasma during positive pulses. This periodic action prevents excessive ion bombardment that would cause surface roughening, while still maintaining strong adhesion through controlled atomic layer-by-layer deposition.
3Productivity
If conventional deposition methods are used to deposit metal shells, then deposition is achieved, but surface roughness increases and adhesion deteriorates
Solution Approach 1:
The bipolar pulsed sputtering process alternates between deposition phases (negative pulses) and plasma clearing phases (positive pulses). This periodic modulation prevents continuous ion bombardment that would roughen the surface, while still achieving efficient metal atom deposition during the negative pulse phases, maintaining both productivity and surface quality.
Solution Approach 2:
By dynamically adjusting pulse width, duty cycle, and power levels during deposition, the process optimizes the balance between deposition rate and surface smoothness. The parameters are tuned to ensure metal atoms deposit in a controlled manner that minimizes surface irregularities while maintaining high deposition efficiency.
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
The method achieves improved etch selectivity and film quality by providing a continuous, smooth metal shell that protects feature sidewalls, allowing for higher aspect ratio etching with reduced surface roughness and increased throughput.
Implementation Method 1
performing a deposition step of depositing a metal shell on the etch mask and exposed surfaces of the underlying material with magnetron sputtering using a series of bipolar pulses
Implementation Method 2
applying a higher power negative pulse to the metal target to dislodge metal atoms therefrom
Implementation Method 3
applying a positive pulse to the metal target to accelerate the metal atoms towards the carbon-containing etch mask
Data Source
AI summary
A method of etching an underlying material includes performing a patterning step of patterning a nonmetal mask layer to form an etch mask that includes openings exposing the underlying material, performing a deposition step of depositing a metal shell on the etch mask and exposed surfaces of the underlying material with magnetron sputtering using a series of bipolar pulses, and performing an etch step of etching the underlying material through the openings of the etch mask after the deposition step. Each bipolar pulse of the series of bipolar pulses may include applying a higher power negative pulse to a metal target to dislodge metal atoms therefrom, and applying a positive pulse to the metal target to accelerate the metal atoms towards the etch mask.