Gas Cluster Ion Beam Etching for High Aspect Ratio Contact Vias
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Solution Overview
Problem
Conventional etch processes, such as reactive ion etch (RIE), fail to achieve acceptable profile control and critical dimension (CD) retention during the opening of high aspect ratio contact vias in semiconductor fabrication, leading to poor electrical properties due to excessive CD loss and corner erosion.
Innovation Solution
The use of gas cluster ion beam (GCIB) processing to etch through a conformal layer at the bottom of contact vias, retaining the second layer on the top surface and sidewalls while minimizing CD loss and corner erosion, by irradiating the substrate with a GCIB according to specific process conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional plasma etch process is used to etch through the conformal layer, then the etching speed is sufficient, but the profile control is poor leading to excessive CD loss and corner erosion
Solution Approach 1:
The patent changes the fundamental etching mechanism from chemical plasma-based etching to physical ion beam-based etching. By using GCIB with controlled ion energy, angle, and flux, the process achieves superior profile control and CD retention through physical sputtering mechanisms rather than chemical reactions, directly resolving the contradiction between manufacturing precision and process complexity
Solution Approach 2:
The patent replaces the chemical plasma etching system with a physical ion beam system. The GCIB process uses accelerated gas cluster ions to physically sputter material, substituting chemical reaction mechanisms with mechanical/physical impact mechanisms, thereby achieving better control over etch profiles and critical dimensions
2Manufacturing precision
If conventional etch process is applied uniformly across the substrate, then the process is simple, but acceptable profile control cannot be achieved uniformly
Solution Approach 1:
The patent applies local quality by enabling independent control of etching parameters across different regions of the substrate. The GCIB system can vary ion energy, incidence angle, and beam flux locally to achieve uniform profile control across the entire substrate, addressing the non-uniformity issue that plagues conventional uniform etching processes
Solution Approach 2:
The patent introduces dynamic control capabilities to the etching process. The GCIB system can dynamically adjust beam parameters during processing to maintain uniform profile control across the substrate, transforming a static uniform etching process into a dynamically controllable process that adapts to local requirements
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
GCIB processing achieves precise control over etch profile and CD retention, reducing CD loss to 2 nm or less and corner erosion, thereby improving the electrical properties of contact vias in semiconductor fabrication.
Implementation Method 1
the etching is performed by irradiating the substrate with a gas cluster ion beam (GCIB) according to a GCIB etching process
Implementation Method 2
GCIB processing achieves precise control over etch profile and CD retention, reducing CD loss to 2 nm or less and corner erosion
Data Source
AI summary
A method for opening a conformal layer at the bottom of a contact via on a substrate is described. The method includes providing a substrate having a first layer with a via pattern formed therein and a second layer conformally deposited on the first layer and within the via pattern to establish a contact via pattern characterized by an initial mid-critical dimension (CD). The method further includes etching through the second layer at the bottom of the contact via pattern to extend the contact via pattern through the second layer and form a contact via while retaining at least part of the second layer on the top surface of the first layer, the corner at the entrance to the via pattern, and the sidewalls of the via pattern, wherein the etching is performed by irradiating the substrate with a gas cluster ion beam (GCIB) according to a GCIB etching process.