Carbon Layer Self-Aligned Structures for High Aspect Ratio Etching
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Solution Overview
Problem
As semiconductor device linewidths shrink, achieving high etch selectivity between layers becomes challenging, requiring improvements in individual processing steps and overall process flow to meet shrinking device criteria, particularly in forming self-aligned structures where traditional lithography and etch tolerances are insufficient.
Innovation Solution
The use of a carbon layer over an etch stop layer, with a cap layer providing protection and selective removal capabilities, allows for the formation of self-aligned structures with high aspect ratios, enabling highly selective etching and protection during subsequent processing steps without damaging underlying layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional lithography and etching techniques are used to form self-aligned structures, then the manufacturing process is simpler, but the structures cannot achieve the required size and alignment precision as device linewidths shrink
Solution Approach 1:
The patent applies preliminary action by forming the carbon layer and cap layer structure before the actual self-aligned structure formation. The carbon layer is deposited over the etch stop layer, and the cap layer is formed over the carbon layer, preparing the structure in advance for subsequent selective removal and self-aligned pattern transfer, thereby achieving high precision without requiring complex real-time alignment processes
Solution Approach 2:
The patent uses the carbon layer as an intermediary material between the etch stop layer and the cap layer. This carbon intermediary enables selective etching processes with greater than 100:1 selectivity, allowing precise removal of the carbon layer to expose the etch stop layer while protecting the underlying structures, thus achieving high alignment precision through the mediating role of the carbon layer
2Length of moving object
If layer thicknesses are reduced to meet shrinking device criteria, then device size is reduced, but aspect ratios increase and etch selectivity becomes more difficult to achieve
Solution Approach 1:
The patent applies parameter changes by utilizing the unique etching parameters of carbon materials. The carbon layer is removed using etching techniques that provide greater than 100:1 selectivity to the etch stop layer, changing the etching parameters to achieve high selectivity even with reduced layer thicknesses and high aspect ratios. This allows precise control of the etching process to meet shrinking device criteria
Solution Approach 2:
The patent uses composite material structure consisting of the carbon layer combined with the cap layer and etch stop layer. The carbon layer provides high etch selectivity, while the cap layer provides mechanical protection and process integration benefits. This composite structure enables achievement of high etch selectivity and reduced damage simultaneously, addressing the contradiction between reduced thickness and manufacturing precision
3Manufacturing precision
If the carbon layer is used to fill high aspect ratio structures, then self-aligned structures with improved precision can be formed, but additional processing steps are required
Solution Approach 1:
The patent applies self-service by using the carbon layer to automatically define the self-aligned contact regions through selective removal. The carbon layer fills the high aspect ratio structures and is subsequently removed in a highly selective manner, allowing the structure itself to guide the alignment process without requiring additional alignment steps, thereby achieving high precision self-aligned structures
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 enables the formation of self-aligned structures with improved etch selectivity and reduced damage, facilitating the integration of high aspect ratio structures and allowing for precise control in semiconductor manufacturing processes.
Implementation Method 1
The carbon layer may be removed via an etching technique that, in one exemplary embodiment, provides greater than 100:1 selectivity to the etch stop layer
Data Source
AI summary
Process integration techniques are disclosed that use a carbon fill layer during formation of self-aligned structures. A carbon layer may be placed over an etch stop layer. A cap layer may be provided over the carbon layer. The carbon layer may fill a high aspect ratio structure formed on the substrate. The carbon layer may be removed from a substrate in a highly selective removal technique in a manner that does not damage underlying layers. The carbon layer may fill a self-aligned contact region that is provided for a self-aligned contact process flow. A tone inversion mask may be used to protect multiple self-aligned contact regions. With the blocking mask in place, the carbon layer may be removed from regions that are not the self-aligned contact region. After removal of the blocking mask, the carbon layer which fills the self-aligned contacts may then be removed.