Tunable Plasma Nitridation for Conformal Low-Temperature Substrates
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Solution Overview
Problem
Conventional nitridation methods, both thermal and plasma-based, face challenges such as high thermal budgets detrimental to substrates and poor conformality of nitride layers, especially in high aspect ratio structures.
Innovation Solution
A plasma processing method using an inductively-coupled plasma source with controlled nitrogen flow and temperature, combined with a heat source, to achieve conformal nitridation of substrates with adjustable nitrogen content and thickness, optionally with hydrogen or oxygen radical treatments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If conventional thermal methods are used for nitridation, then nitrogen content can be achieved, but substrate temperature becomes too high which is detrimental to the substrate
Solution Approach 1:
The patent changes the fundamental parameter of the nitridation process from thermal to plasma-based. By using inductively coupled plasma with nitrogen-containing gases (NH3, N2, N2H4) at controlled power levels (2,000-10,000 W) and flow rates (3%-20% nitrogen source to carrier gas), nitrogen is delivered to the substrate in reactive radical form without requiring high substrate temperatures (maintained at 150°C-650°C), thus achieving nitrogen incorporation while protecting the substrate from thermal damage
Solution Approach 2:
The patent replaces the thermal mechanism (heat-driven nitrogen diffusion) with a plasma-based mechanism. The inductively coupled plasma source generates reactive nitrogen species through electromagnetic field coupling, which then chemically react with the substrate surface at lower temperatures, substituting the thermal field with a combined electromagnetic and chemical field approach
2Temperature
If conventional plasma-based nitridation is used, then processing temperature can be reduced, but conformality of nitride layer becomes poor especially in high aspect ratio structures
Solution Approach 1:
The patent employs dynamic control of plasma parameters including adjustable power levels (2,000-10,000 W), variable gas flow rates (3%-20% nitrogen source to carrier gas ratio), and controlled pressure (50 mTorr-2 Torr) to optimize the balance between plasma reactivity and uniformity. This dynamic parameter adjustment enables conformal nitride layer deposition in high aspect ratio structures while maintaining lower processing temperatures
Solution Approach 2:
The patent optimizes multiple process parameters simultaneously: nitrogen-containing source flow rate (3%-20% of carrier gas), plasma power (2,000-10,000 W), pressure (50 mTorr-2 Torr), and temperature (150°C-650°C) to achieve both low thermal budget and high conformality. The specific parameter combination creates optimal conditions for radical species generation and uniform substrate coverage
3Quantity of substance
If higher nitrogen dosing is achieved through conventional methods, then nitrogen content increases, but thermal budget increases which damages the substrate
Solution Approach 1:
The patent replaces thermal nitrogen delivery with plasma-based nitrogen radical delivery. The inductively coupled plasma generates highly reactive nitrogen species (N, NH, NH2 radicals) from nitrogen-containing gases, which can be incorporated into the substrate at much lower temperatures. This substitution allows high nitrogen dosing without proportional increase in thermal budget, as the chemical reactivity is enhanced through plasma activation rather than thermal energy
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 higher nitrogen dosing and conformal nitridation with lower thermal budgets, suitable for semiconductor substrates, improving processing efficiency and uniformity.
Implementation Method 1
generating an inductively-coupled plasma in the plasma processing source by operating an inductively-coupled plasma source at a power of about 2,000 W to about 10,000 W
Implementation Method 2
the inductively-coupled plasma comprising a radical species formed from the nitrogen-containing source, the carrier gas, or both
Implementation Method 3
operating a heat source within the processing chamber at a temperature from about 150° C. to about 650° C. to heat the substrate
Implementation Method 4
adjusting a nitrogen content, a number of nitrogen atoms per unit area, a nitride thickness, or combinations thereof, of the substrate by exposing the substrate to the radical species
Data Source
AI summary
In an embodiment, a method for nitriding a substrate is provided. The method includes flowing a nitrogen-containing source and a carrier gas into a plasma processing source coupled to a chamber such that a flow rate of the nitrogen-containing source is from about 3% to 20% of a flow rate of the carrier gas; generating an inductively-coupled plasma (ICP) in the plasma processing source by operating an ICP source, the ICP comprising a radical species formed from the nitrogen-containing source, the carrier gas, or both; and nitriding the substrate within the chamber, wherein nitriding includes operating a heat source within the chamber at a temperature from about 150° C. to about 650° C. to heat the substrate; maintaining a pressure of the chamber from about 50 mTorr to about 2 Torr; introducing the ICP to the chamber; and adjusting a characteristic of the substrate by exposing the substrate to the radical species.