Oxide Layer Etching Using Fluorine Nitrogen Reaction Gas
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Solution Overview
Problem
Conventional semiconductor device isolation processes, such as LOCOS and STI, face challenges in forming oxide layers within high aspect ratio trenches, leading to voids and seams, and excessive etching causes damage and reduces reliability.
Innovation Solution
A method using a reaction gas with fluorine and nitrogen, specifically hydrofluoric acid (HF) vapor and ammonia (NH3), to etch the oxide layer, forming byproducts that are then removed, minimizing damage and voids, and allowing for conformal filling of trenches with a second oxide layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If wet etching or plasma etching is used to remove oxide layer, then oxide removal is achieved, but excessive etching damage occurs to semiconductor device
Solution Approach 1:
The patent changes the chemical parameters of the etching process by using a buffered oxide etch (BOE) solution with specific composition ratios and controlling temperature and time parameters, achieving precise oxide removal without excessive damage to the semiconductor device
Solution Approach 2:
The patent introduces a buffered etch solution as an intermediary medium that selectively removes oxide layers while protecting underlying structures, acting as a mediator between the aggressive etching needed for oxide removal and the protection needed for device integrity
2Manufacturing precision
If hydrogen gas is used during HDP-CVD to minimize voids and seams, then deposition uniformity improves, but active pitting phenomenon occurs in active region
Solution Approach 1:
The patent extracts or removes the hydrogen gas from the deposition process, eliminating the source of active pitting while maintaining deposition uniformity through alternative process control methods
Solution Approach 2:
The patent converts the harmful effect of hydrogen-induced pitting into a beneficial process by adjusting deposition parameters to achieve uniform coverage without hydrogen, turning a problematic condition into an optimized process
3Object-affected harmful factors
If RF power is reduced to minimize etching damage, then device damage decreases, but gap-fill ability of oxide layer degrades
Solution Approach 1:
The patent changes multiple process parameters including temperature, pressure, and gas flow rates to compensate for reduced RF power, maintaining both low damage and good gap-fill ability through coordinated parameter optimization
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 minimizes voids and seams in the oxide layer, reduces substrate damage, and enhances the reliability and operability of semiconductor devices by enabling precise control over the etching process and uniform deposition.
Implementation Method 1
forming first byproducts by reacting a reaction gas with the oxide of the oxide layer, the reaction gas having fluorine and nitrogen
Implementation Method 2
deposition and sputtering may be performed at the same time. Accordingly, the oxide layer deposited in an upper portion of the trench may be sputtered and reattached
Data Source
AI summary
A method of removing a portion of an oxide layer includes forming first byproducts by reacting a reaction gas with the oxide layer, the reaction gas including fluorine and nitrogen, reacting the reaction gas with the first byproducts to form second byproducts, and removing the second byproducts.