Deuterated Gate Stack Passivation for SONOS Memory Retention
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Solution Overview
Problem
Conventional methods for passivating interface traps in non-volatile charge trap memory devices, such as SONOS devices, using deuterium anneals are limited by the need for pure deuterium gas and high temperatures, which pose safety hazards and increase the thermal budget, and are ineffective in devices with nitride layers.
Innovation Solution
Incorporating deuterium into the gate stack and sidewall spacers of SONOS devices during deposition using deuterated precursor gases like ND3 and SiD4, allowing for thermal cycles to diffuse deuterium and passivate interface traps without the need for subsequent annealing, thereby reducing the thermal budget and improving device reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If deuterium anneal is used to passivate interface traps, then device reliability is improved, but thermal budget increases and safety hazards arise
Solution Approach 1:
Deuterium is incorporated into the gate stack and sidewall spacers during the deposition process itself, rather than requiring a separate post-fabrication annealing step. This preliminary incorporation of deuterium during deposition eliminates the need for high-temperature annealing while still achieving effective passivation of interface traps, thus resolving the contradiction between improving reliability and reducing thermal budget
Solution Approach 2:
Deuterated precursor gases (such as SiD4 and ND3) serve as intermediaries to deliver deuterium to the gate stack and sidewall spacers during deposition. These deuterated precursors enable deuterium incorporation without requiring pure deuterium gas handling or high-temperature annealing, thereby improving safety while maintaining passivation effectiveness
2Reliability
If deuterium anneal is used to passivate interface traps, then interface trap passivation is achieved, but pure deuterium gas handling becomes necessary
Solution Approach 1:
The invention changes the form in which deuterium is delivered - instead of using pure deuterium gas (D2) which poses safety hazards, deuterium is incorporated through deuterated precursor gases (such as SiD4 and ND3) during deposition. This parameter change in the delivery mechanism eliminates safety hazards while maintaining the ability to passivate interface traps effectively
Solution Approach 2:
Deuterated precursor gases act as safe intermediaries that deliver deuterium during deposition without requiring handling of pure deuterium gas. These precursors can be safely handled during standard deposition processes while still achieving the desired deuterium incorporation for interface trap passivation
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 enhances the retention time and reduces the threshold voltage decay rate of SONOS devices, improving their long-term performance and compatibility with advanced semiconductor fabrication techniques.
Implementation Method 1
thermal cycles to diffuse deuterium and passivate interface traps
Implementation Method 2
Incorporating deuterium into the gate stack and sidewall spacers of SONOS devices during deposition using deuterated precursor gases like ND3 and SiD4
Data Source
AI summary
A nonvolatile charge trap memory device with deuterium passivation of charge traps and method of manufacture. Deuterated gate layer, deuterated gate cap layer and deuterated spacers are employed in various combinations to encapsulate the device with deuterium sources proximate to the interfaces within the gate stack and on the surface of the gate stack where traps may be present.