Selective PEALD Layer Formation on Complex Surface Topologies
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Solution Overview
Problem
Existing methods for forming a layer on specific surfaces of a substrate with complex topology, such as etching masks, require numerous steps and suffer from limited accuracy due to the need for multiple masks and alignment tolerances, making them long and expensive to implement.
Innovation Solution
A method using plasma-enhanced atomic layer deposition (PEALD) with controlled temperature and polarisation to selectively deposit a layer on certain surfaces, where the PEALD cycles are performed at a temperature below the nominal window and the substrate is exposed to a densification plasma with a polarisation voltage, creating regions with different material properties to facilitate selective etching and improve accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional lithography with multiple masks is used to form a layer on specific surfaces, then the layer can be deposited on targeted areas, but the process requires numerous steps and has limited accuracy due to alignment tolerances
Solution Approach 1:
The invention extracts and eliminates the lithography step entirely from the process. Instead of using multiple masks to define patterns, the method directly deposits material only on the desired surfaces through selective area deposition techniques, removing the intermediate lithography complexity while improving precision
Solution Approach 2:
The invention performs preliminary surface preparation and masking in a single step before deposition. By pre-defining the deposition areas through surface treatment or single-step masking, the process eliminates the need for multiple alignment steps during actual layer formation, thereby improving accuracy and reducing complexity
2Manufacturing precision
If conventional lithography steps are used to remove layer on vertical surfaces, then selective coverage can be achieved, but the process is long and expensive to implement
Solution Approach 1:
Instead of depositing a complete layer and then removing material from unwanted areas (subtractive approach), the invention inverts the approach by directly depositing material only on the desired surfaces from the beginning (additive approach). This eliminates the time-consuming etching and cleaning steps while achieving the same selective coverage
Solution Approach 2:
The invention employs self-aligned deposition techniques where the deposition process itself automatically confines material to specific surfaces through surface energy differences, physical barriers, or in-situ formed masks. This self-service mechanism eliminates the need for separate lithography and etching steps, dramatically reducing process time and cost
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 enables precise and cost-effective deposition of layers on specific surfaces without the need for conventional lithography, improving the accuracy and quality of the deposited film, and allowing for the selective removal of unwanted regions while preserving the desired layer on horizontal surfaces.
Implementation Method 1
a sequence of forming an initial layer by plasma-enhanced atomic layer deposition (PEALD) on the front face of the structure
Implementation Method 2
a sequence of exposing the initial layer to a plasma with an applied polarisation, called densification plasma
Data Source
AI summary
A method for producing a layer covering the first surfaces of a structure and leaving the second surfaces uncovered including a sequence for forming an initial layer by PEALD deposition, the sequence including cycles, each including injections of first and second precursor in a reaction chamber, and plasma formation in the reaction chamber. The cycles are carried out at a temperature Tcycle such that Tcycle≤ (Tmin - 20° C.), Tmin being the minimum temperature of a nominal temperature window for a PEALD deposition. The method includes exposing the initial layer to a densification plasma such that the exposure to the ion flow makes the material on the first surfaces more resistant to etching than the material on the second surfaces. The method also includes a selective etching step, such that the initial layer covers the first surfaces of the front face of the structure by leaving the second surfaces uncovered.