Remote Plasma Nitridation of Dielectric Layers
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Solution Overview
Problem
Conventional methods for incorporating nitrogen into gate dielectric layers in integrated circuits face challenges such as difficulty in controlling nitrogen incorporation, especially at low temperatures, and high temperatures can cause unintended reactions and damage, leading to inefficient nitridation and increased costs.
Innovation Solution
A method involving a single substrate reaction chamber where ammonia is exposed to an excited nitrogen species generated remotely, allowing for efficient nitrogen incorporation into the substrate without the drawbacks of high-temperature nitridation or in situ plasma damage, using a combination of ammonia and nitrogen radicals or metastable species to enhance nitrogen incorporation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If conventional high-temperature nitridation methods are used, then nitrogen incorporation into dielectric layers is achieved, but unintended reactions and damage occur
Solution Approach 1:
The patent applies preliminary action by pre-dissociating nitrogen gas into reactive nitrogen species in a remote plasma source before introducing them to the dielectric layer. This preliminary activation of nitrogen allows for effective nitridation at lower temperatures, preventing the unintended reactions and damage that occur with conventional high-temperature methods while still achieving the desired nitrogen incorporation into the gate dielectric layer.
2Object-affected harmful factors
If low-temperature nitridation is used, then damage is minimized, but nitrogen incorporation control is difficult
Solution Approach 1:
The patent uses an intermediary approach by introducing ammonia gas as a mediator between the remote plasma source and the dielectric layer. The ammonia serves as a nitrogen precursor that reacts with the plasma-generated species to provide controlled nitrogen delivery. This intermediary mechanism enables precise control of nitrogen incorporation rates at low temperatures, overcoming the difficulty of controlling nitrogen uptake while maintaining minimal damage to the dielectric layer.
3Quantity of substance
If in situ plasma nitridation is used, then nitrogen incorporation is enhanced, but plasma damage occurs
Solution Approach 1:
The patent applies the extraction principle by removing the plasma generation process from the reaction chamber where the dielectric layer is located. The nitrogen gas is dissociated into reactive species in a separate remote plasma source upstream, and only the activated nitrogen species are transported to the dielectric layer for nitridation. This separation extracts the damaging plasma conditions from the sensitive dielectric processing environment while retaining the beneficial nitrogen incorporation effects.
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 achieves nitrogen incorporation levels greater than 5% at lower temperatures, improving the thermal and electrical stability of dielectric layers while minimizing damage and cost, with enhanced deposition rates and refractive index indicating effective nitrogen distribution.
Implementation Method 1
exposed to an excited species generator... generating nitrogen radicals in a reaction chamber by exposing ammonia to the excited species
Data Source
AI summary
A nitrogen precursor that has been activated by exposure to a remotely excited species is used as a reactant to form nitrogen-containing layers. The remotely excited species can be, e.g., N2, Ar, and/or He, which has been excited in a microwave radical generator. Downstream of the microwave radical generator and upstream of the substrate, the flow of excited species is mixed with a flow of NH3. The excited species activates the NH3. The substrate is exposed to both the activated NH3 and the excited species. The substrate can also be exposed to a precursor of another species to form a compound layer in a chemical vapor deposition. In addition, already-deposited layers can be nitrided by exposure to the activated NH3 and to the excited species, which results in higher levels of nitrogen incorporation than plasma nitridation using excited N2 alone, or thermal nitridation using NH3 alone, with the same process temperatures and nitridation durations.