Post-Etch Defluorination for Stable Plasma Photoresist Stripping
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Solution Overview
Problem
Plasma strip processes in semiconductor fabrication are hindered by residual fluorine, which reacts with metal layers, leading to contamination and reduced strip rates due to the formation of volatile tungsten oxides and oxy-fluorides, affecting the stability of the processing chamber.
Innovation Solution
A defluorination process using hydrogen radicals is implemented prior to plasma strip processes to react with and remove fluorine residuals, generating HF molecules that are evacuated, thereby reducing contamination and maintaining strip rate efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If plasma strip process is performed directly after etch process, then photoresist removal can proceed, but fluorine residuals react with metal layers causing contamination and reduced strip rates
Solution Approach 1:
A defluorination process is performed before the plasma strip process to remove fluorine residuals from the workpiece surface. This preliminary action prevents fluorine contamination during the subsequent photoresist removal step, thereby maintaining high strip rates without the harmful effects of fluorine-metal reactions.
Solution Approach 2:
The harmful fluorine residuals are converted into beneficial hydrogen fluoride (HF) molecules through reaction with hydrogen radicals. This transformation eliminates the contaminating effect of fluorine while producing a volatile compound (HF) that can be easily evacuated from the chamber, thus converting a harmful substance into a removable byproduct.
2Object-affected harmful factors
If defluorination process using hydrogen radicals is implemented, then fluorine residuals are removed, but additional process step is required
Solution Approach 1:
The defluorination process and plasma strip process are combined into a single integrated process chamber. By generating hydrogen radicals in-situ within the same chamber used for photoresist removal, the system eliminates the need for separate processing equipment and reduces the number of discrete process steps, thereby minimizing added complexity while effectively removing fluorine residuals.
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
The in-situ defluorination process effectively reduces fluorine residual-related contamination and maintains the stability of the plasma strip process by removing fluorine from the workpiece, ensuring consistent photoresist removal without compromising the processing chamber's stability.
Implementation Method 1
performing a defluorination process on the workpiece at least in part using a plasma generated from a first process gas
Implementation Method 2
A defluorination process using hydrogen radicals is implemented prior to plasma strip processes to react with and remove fluorine residuals, generating HF molecules
Data Source
AI summary
Defluorination processes for removing fluorine residuals from a workpiece such as a semiconductor wafer are provided. In one example implementation, a method for processing a workpiece can include supporting a workpiece on a workpiece support. The workpiece can have a photoresist layer. The workpiece can have one or more fluorine residuals on a surface of the workpiece. The method can include performing a defluorination process on the workpiece at least in part using a plasma generated from a first process gas. The first process gas can include a hydrogen gas. Subsequent to performing the defluorination process, the method can include performing a plasma strip process on the workpiece to at least partially remove a photoresist layer from the workpiece.