Plasma Etching with Refractory Metal Sputtering for CD Control
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Solution Overview
Problem
The semiconductor industry faces challenges in achieving accurate and precise patterning of high aspect ratio features in 3D semiconductor devices due to limitations in mask materials and etch selectivity, leading to issues like bowing and poor critical dimension control during plasma etching processes.
Innovation Solution
The method involves a plasma etching process that incorporates metal sputtering and deposition using a metal-containing chamber part, such as a refractory metal, to form a passivation layer over the substrate, which enhances sidewall protection and improves critical dimension control by tuning plasma process conditions to achieve a radial gradient of metal deposition, increasing metal concentration at the edge over the center.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional plasma etching processes are used, then etching can be performed, but bowing occurs and critical dimension control is poor
Solution Approach 1:
A metal-containing chamber part (intermediary) is introduced between the plasma source and the substrate to mediate the etching process. This intermediary component sputters metal atoms into the plasma, which then deposit on the substrate to form a conductive polymer layer that prevents bowing and improves critical dimension control during high aspect ratio feature etching.
Solution Approach 2:
The plasma process parameters are modified by introducing metal atoms from the chamber part into the plasma. This changes the plasma composition and chemistry, enabling the formation of a conductive polymer layer on the substrate that stabilizes the etching process and eliminates bowing while maintaining precise critical dimension control.
2Reliability
If metal sputtering is performed to form passivation layer, then sidewall protection improves, but process complexity increases
Solution Approach 1:
The chamber part itself serves as the metal source through self-sputtering during the plasma etching process. The metal atoms are liberated from the chamber part surface by plasma bombardment and automatically deposit on the substrate to form the protective conductive polymer layer, eliminating the need for separate metal deposition steps and simplifying the overall process.
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 effectively reduces bowing and improves edge critical dimension control, enabling the fabrication of high aspect ratio features with enhanced precision and accuracy in 3D semiconductor devices.
Implementation Method 1
exposing the surface of the chamber part to the plasma to sputter the refractory metal from the surface of the chamber part
Implementation Method 2
etching the underlying layer, the etching including exposing the substrate to the plasma
Data Source
AI summary
A method of etching a substrate that includes: loading the substrate into a plasma etch chamber, the substrate including a patterned hard mask layer and an underlying layer, the plasma etch chamber including a chamber part having a surface including a refractory metal, and a first electrode; flowing a process gas including fluorine and carbon into the plasma etch chamber; applying a source power to the first electrode of the plasma etch chamber to generate a plasma in the plasma etch chamber; and etching the underlying layer, the etching including exposing the surface of the chamber part to the plasma to sputter the refractory metal from the surface of the chamber part, and forming a recess in the underlying layer and a conductive polymer layer including the refractory metal over sidewalls of the patterned hard mask layer and the underlying layer, the forming including exposing the substrate to the plasma.