Chlorine Plasma Modification for Selective Nano-Crystal Etching
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for removing nano-crystals, such as platinum, during semiconductor device manufacturing are inefficient and damage the underlying tunnel oxide layer due to their physical etching processes, which lack selectivity.
Innovation Solution
Exposing nano-crystals to low energy free radical or ionic chlorine in a high density plasma modifies them, allowing for their removal using wet etchants without damaging the tunnel oxide, employing a process that includes a high density plasma with chlorine sources like BCl3, Cl2, and SiCl4, and subsequent treatment with dilute HF or aqua regia.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If physical etching processes are used to remove platinum nano-crystals, then the nano-crystals can be removed, but the underlying tunnel oxide layer is damaged and etch selectivity is low
Solution Approach 1:
The patent changes the etching mechanism from physical (sputtering) to chemical by introducing a chlorine-based plasma process. This parameter change in the etching chemistry enables selective removal of platinum nano-crystals while preserving the tunnel oxide layer, directly resolving the contradiction between etch selectivity and oxide layer damage
Solution Approach 2:
The patent replaces the mechanical/physical sputtering process with a chemical plasma etching process using chlorine radicals. This substitution eliminates the mechanical bombardment that damages the oxide layer while maintaining effective removal of platinum nano-crystals through chemical reactions
2Productivity
If sputtering process is used to remove platinum, then platinum nano-crystals can be removed, but the process has very low etch selectivity for the underlying tunnel oxide layer
Solution Approach 1:
The patent modifies the etching parameters by using chlorine-containing plasma instead of physical sputtering. This chemical approach maintains high removal efficiency for platinum while achieving high selectivity for the tunnel oxide layer, simultaneously improving both productivity and manufacturing precision
3Manufacturing precision
If conventional wet etchants are used, then they cannot remove platinum nano-crystals effectively, but they also do not damage the tunnel oxide layer
Solution Approach 1:
The patent creates a composite etching approach by combining chlorine-based plasma treatment with subsequent wet etching. The plasma treatment modifies the platinum surface to enhance wet etchant effectiveness, achieving both high removal efficiency and oxide layer protection
Solution Approach 2:
The patent applies preliminary chlorine plasma treatment to the platinum nano-crystals before wet etching. This preliminary action activates the platinum surface, making it susceptible to wet etchant removal while the tunnel oxide remains protected, thereby improving both selectivity and removal effectiveness
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 selective and damage-free removal of nano-crystals, enhancing etch selectivity and preventing attack on the tunnel oxide, thus facilitating the manufacturing process of semiconductor devices like flash memory devices.
Implementation Method 1
exposing the nano-crystals to low energy free radical or ionic chlorine in a high density plasma modifies them
Implementation Method 2
high density plasma comprising a source of free radical chlorine
Implementation Method 3
high density plasma comprising a source of ionic chlorine
Implementation Method 4
removing the modified nano-crystals with a wet etchant
Data Source
AI summary
A method for selectively removing nano-crystals on an insulating layer. The method includes providing an insulating layer with nano-crystals thereon; exposing the nano-crystals to a high density plasma comprising a source of free radical chlorine, ionic chlorine, or both to modify the nano-crystals; and removing the modified nano-crystals with a wet etchant.