Plasma Spacer Etching with Carbon-Fluorine Ratio Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The etching process in semiconductor manufacturing often results in nonuniform etching rates across different positions of a workpiece, leading to over-etching and excessive loss of the underlying substrate, which reduces yield and finished product ratio.
Innovation Solution
A plasma etching process is developed that modulates the volume ratio of carbon to fluorine in the etching gas to control the distribution of a carbon-based polymer layer on the spacer layer, allowing for simultaneous opening of top and bottom silicon oxide layers while minimizing over-etching time and substrate loss by adjusting the thickness of the polymer layer formed on different regions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional plasma etching is used, then etching process is simple, but etching rate is nonuniform across different positions of workpiece
Solution Approach 1:
The patent applies local quality by introducing a composition modulation gas (CHF3 or CF4) that selectively modulates the polymer layer thickness at different spatial locations on the workpiece. The modulation gas concentration is varied across the etching chamber to create location-dependent etching rates, achieving uniform overall etching by compensating for position-dependent variations through localized polymer deposition control.
2Manufacturing precision
If etching continues to complete the process, then top and bottom layers are opened, but over-etching occurs causing substrate loss
Solution Approach 1:
The patent applies preliminary action by pre-forming a polymer layer on the spacer layer before and during the etching process. This polymer layer acts as a protective barrier that prevents excessive etching into the underlying substrate. The polymer layer is formed by introducing a carbon-containing gas (CH4, C4F8, or C3F8) prior to or concurrent with the etching gas, creating a protective cushion that limits the depth of etching and prevents substrate damage.
Solution Approach 2:
The patent uses a polymer layer as an intermediary substance between the etching plasma and the spacer layer/substrate. This polymer intermediary controls the etching rate by providing a protective barrier that modulates the interaction between reactive plasma species and the workpiece surface, enabling precise control over etching depth and preventing direct damage to the substrate.
3Loss of substance
If polymer layer thickness is increased to protect substrate, then substrate loss is reduced, but etching rate decreases
Solution Approach 1:
The patent applies dynamics by dynamically controlling the thickness and composition of the polymer layer during the etching process. The polymer layer thickness is not static but is modulated in real-time by adjusting the flow rates of modulation gases and etching gases, allowing the system to adapt the protective barrier thickness to match the instantaneous etching conditions and maintain optimal etching rate while preventing substrate damage.
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 optimizes the etching process to reduce over-etching time, minimize substrate loss, and enhance the yield and finished product ratio by ensuring uniform etching across the workpiece, laying a foundation for miniaturization.
Implementation Method 1
generating one or more species using one or more plasmas from a process gas
Implementation Method 2
form a polymer layer on at least a portion of the spacer layer
Implementation Method 3
etch at least a portion of the spacer layer of the workpiece
Implementation Method 4
exposing the workpiece to the mixture to form a polymer layer and to etch
Data Source
AI summary
A method for processing a workpiece, a plasma processing apparatus and a semiconductor device are provided. The method includes placing a workpiece including a spacer layer on a workpiece support in a chamber; selecting a composition modulation gas to modulate a volume ratio of carbon and fluorine to process the workpiece, the composition modulation gas includes one or more molecules, the volume ratio of carbon and fluorine is indicative of a distribution of carbon-based polymer deposited on the spacer layer; generating one or more species using one or more plasmas from a process gas to create a mixture, the process gas includes an etching gas and the composition modulation gas; and exposing the workpiece to the mixture to form a polymer layer on at least a portion of the spacer layer and to etch at least a portion of the spacer layer.