Stepped Structure Silicon Nitride Deposition with PECVD Plasma Tuning
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Solution Overview
Problem
Existing methods for depositing thin films on 3D stacked memory structures with stepped surfaces, such as Plasma Enhanced Atomic Layer Deposition (PEALD), are inefficient due to slow deposition rates and inability to uniformly coat complex geometries.
Innovation Solution
A method using Plasma Enhanced Chemical Vapor Deposition (PECVD) with controlled pressure and RF plasma power to deposit silicon nitride on the top, bottom, and sidewalls of a stepped substrate, employing halogenated silane as a precursor and ammonia as a nitrogen reactant, while applying RF plasma power between electrodes to achieve differential etch rates and improved film properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If PEALD is used to form thin film on stepped structure, then film uniformity is improved, but deposition rate becomes slow
Solution Approach 1:
The patent combines PECVD and ALD into a hybrid process sequence. PECVD is used first for rapid deposition to build up material quickly on the stepped structure, followed by ALD to provide a thin conformal layer that ensures uniformity and protects the underlying structure. This merging of processes allows the system to achieve both high deposition rates and good film uniformity that neither process could achieve alone.
2Productivity
If PECVD is used with controlled pressure and RF plasma power, then deposition rate increases, but film uniformity may deteriorate
Solution Approach 1:
The patent systematically optimizes PECVD process parameters including pressure (maintained at 200 Pa or less), RF plasma power (set to 0.21 W/cm2 or more), precursor flow rates, and reactant flow rates. These parameter changes are specifically tuned to achieve both high deposition rates and acceptable film uniformity on stepped structures, representing a departure from conventional PECVD parameter settings.
Solution Approach 2:
The patent employs a periodic hybrid process sequence alternating between PECVD and ALD steps. The PECVD phase deposits material rapidly when parameters favor high rate, then the process switches to ALD phase to restore film uniformity. This periodic switching between two deposition modes allows the system to maintain both high overall deposition rate and good film quality throughout the manufacturing process.
3Productivity
If conventional PECVD is used on stepped structure, then deposition rate is fast, but selective etching capability is lost
Solution Approach 1:
The patent creates local quality differences in the deposited film by controlling plasma conditions during PECVD. By adjusting pressure and RF power parameters, the film composition and structure vary locally - particularly on sidewalls versus top surfaces - creating regions with different etch selectivity. This allows subsequent selective etching processes to differentiate between various surfaces of the stepped structure, adding versatility to the overall manufacturing process.
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 method enables faster deposition rates and selective etching of sidewall portions compared to top surfaces, enhancing film uniformity and deposition efficiency on complex structures.
Implementation Method 1
providing a plasma with a RF plasma power wherein by simultaneously providing the precursor, the reactant, and the plasma while controlling the process pressure to less than or equal to 200 Pa and controlling the RF plasma power to more than or equal to 0.21 W per cm2 the material is deposited on the top surface, the bottom surface, and the sidewall of the stepped structure
Data Source
AI summary
A method for depositing material is disclosed. An exemplary method includes positioning a substrate provided with a stepped structure comprising a top surface, a bottom surface, and a sidewall in a reaction chamber; controlling a pressure of the reaction chamber to a process pressure; providing a precursor; providing a reactant; and, providing a plasma with a RF plasma power, wherein by simultaneously providing the precursor, the reactant, and the plasma while controlling the process pressure to less than or equal to 200 Pa and controlling the RF plasma power to more than or equal to 0.21 W per cm2 the material is deposited on the top surface, the bottom surface, and the sidewall of the stepped structure.