Angled Ion Beam Deposition for Composite Mask Patterning
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Solution Overview
Problem
Current substrate patterning techniques face challenges in creating deep trenches or vias with high aspect ratios, as conventional mask materials often result in faceting, clogging, or tapering during etching, and using materials with lower etch rates makes patterning impractical.
Innovation Solution
A method involving the formation of a composite mask feature by directing ions at a non-zero angle of incidence to create a cap layer on an initial mask feature, allowing for a sacrificial mask that is etched at different rates, reducing the thickness of the initial mask and enabling deeper etching without unwanted deposition on the substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If a thick mask material is used to etch deep trenches, then the etch depth is improved, but the mask features experience faceting, clogging, and bowing
Solution Approach 1:
The mask structure is segmented into multiple functional layers: a sacrificial mask layer (carbon-based) that defines the pattern and a protective cap layer (oxide or nitride) that prevents faceting and clogging. This segmentation allows each layer to perform its specific function - the sacrificial mask provides pattern definition while the cap layer maintains structural integrity during deep etching
Solution Approach 2:
The invention uses composite mask structures combining different materials with complementary properties. The carbon-based sacrificial mask layer provides good etch selectivity and pattern definition, while the oxide or nitride cap layer provides mechanical strength and resistance to faceting. This composite approach resolves the contradiction between achieving deep etch depth and maintaining mask feature shape accuracy
2Length of stationary object
If a mask material with lower etch rate is used, then the mask thickness can be reduced, but patterning becomes impractical
Solution Approach 1:
Different regions of the mask structure have different material compositions optimized for their specific functions. The sacrificial mask layer uses carbon-based materials that are easily patterned with standard lithography, while the cap layer uses oxide or nitride materials that provide etch resistance. This local differentiation of material properties allows thin mask thickness while maintaining patterning feasibility
Solution Approach 2:
The invention changes the etch rate parameter by using a composite structure where the sacrificial mask layer has a higher etch rate than the cap layer. This parameter differentiation allows the thin sacrificial mask to be removed after etching while the cap layer remains to protect the underlying structure, making thin mask patterning practical
3Length of stationary object
If a thick mask is used for deep etching, then the etch depth is achieved, but unwanted deposition occurs on the substrate
Solution Approach 1:
The harmful function of material deposition on the substrate is extracted and redirected to the cap layer. The oxide or nitride cap layer acts as a sacrificial barrier that absorbs the deposition that would otherwise occur on the substrate, protecting the underlying structures while enabling deep 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 approach allows for deeper substrate etching with reduced mask thickness and prevents faceting or clogging, achieving more precise and deeper patterned features with improved etch resistance.
Implementation Method 1
directing ions as an ion beam to the initial mask feature at a non-zero angle of incidence θ with respect to a perpendicular to the substrate plane, wherein a composite mask feature is formed, the composite mask feature comprising a cap material disposed on the initial mask feature, the cap material comprising the ions
Data Source
AI summary
A method may include providing an initial mask feature in a mask disposed on a substrate, the initial mask feature comprising a first material, the substrate defining a substrate plane; directing ions as an ion beam to the initial mask feature at a non-zero angle of incidence θ with respect to a perpendicular to the substrate plane, wherein a composite mask feature is formed, the composite mask feature comprising a cap material disposed on the initial mask feature, the cap material comprising the ions; and performing a substrate etch, wherein an etch feature is formed in the substrate, wherein at least a portion of the initial mask feature remains after the substrate etch, wherein the substrate etch etches the first material at a first etch rate and etches the cap material at a second etch rate, the first etch rate being greater than the second etch rate.