Atomic Layer TaN Etching for Selectivity and Low Surface Roughness
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Solution Overview
Problem
Conventional methods for etching tantalum nitride films in 3D NAND flash manufacturing face challenges in achieving excellent etching selectivity and minimizing surface roughness, leading to potential device failures due to leakage current.
Innovation Solution
A substrate processing method involving surface modification with oxygen gas followed by etching with CHF3 gas at the atomic layer level, with optional repetition of cycles and substrate heating between 100° C to 150° C, to achieve selective etching and reduce surface roughness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional RIE process is used to etch tantalum nitride film, then etching speed is maintained, but etching selectivity to silicon oxide and silicon nitride films deteriorates and surface roughness increases
Solution Approach 1:
The etching process is divided into multiple sequential steps with different gases: first O2 plasma for surface oxidation, then BCl3 for modification, and finally HF for selective etching. This segmentation allows each step to optimize for its specific function, achieving both high selectivity and controlled etching rate.
Solution Approach 2:
Oxygen is introduced as an intermediary substance to oxidize the tantalum nitride surface before etching. This oxidation layer serves as a mediator that enables selective removal of the tantalum nitride film while protecting the underlying silicon oxide and silicon nitride layers, thereby improving etching selectivity.
2Manufacturing precision
If atomic layer etching process is used to improve etching selectivity, then manufacturing precision is improved, but process complexity increases
Solution Approach 1:
The process uses parameter changes in the form of sequential gas introductions (O2, then BCl3, then HF) with controlled timing and flow rates. Each gas introduces specific chemical reactions at controlled rates, enabling precise control of etching depth and selectivity while managing process complexity through systematic parameter variation.
3Manufacturing precision
If multiple etching cycles are performed to achieve desired etching depth, then etching precision is improved, but processing time increases
Solution Approach 1:
The etching process maintains continuous useful action by seamlessly transitioning between gas phases without breaking vacuum or interrupting the process flow. The oxidation, modification, and etching steps occur in continuous sequence, maximizing the efficiency of each cycle and reducing idle time between operations.
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 provides excellent etching selectivity and reduces surface roughness of tantalum nitride films, thereby minimizing device defects caused by leakage current and enhancing the manufacturing process for 3D NAND devices.
Implementation Method 1
a surface modification step of modifying a surface of the thin film by supplying a first gas including oxygen (O) to a processing space of a chamber
Implementation Method 2
an etching step of etching the modified thin film by supplying a CHF3 gas to the processing space
Implementation Method 3
the substrate may be heated to a predetermined temperature... The predetermined temperature may be 100° C. to 150° C.
Data Source
AI summary
Proposed are a substrate processing method and a substrate processing apparatus. A substrate processing method according to an embodiment is for etching a thin film formed on a substrate at the atomic layer level, and includes a surface modification step of modifying a surface of the thin film by supplying a first gas including oxygen (O) to a processing space of a chamber in which the substrate is placed, a first purge step of removing the first gas remaining in the processing space by supplying a purge gas to the processing space, an etching step of etching the modified thin film by supplying a CHF3 gas to the processing space, and a second purge step of removing the CHF3 gas remaining in the processing space by supplying the purge gas to the processing space.