SONOS Memory Fabrication Sequence Inversion

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Conventional SONOS memory fabrication methods result in uneven charge distribution and increased threshold voltage range, leading to sensing errors and reduced memory performance due to the order of annealing and ultraviolet treatment processes.

Innovation Solution

Performing an ultraviolet treatment after the fabrication of the passivation layer and contact pads, followed by an annealing process, to achieve a more even charge distribution and narrower threshold voltage range.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If annealing process is performed before ultraviolet treatment in conventional SONOS memory fabrication, then the fabrication sequence follows standard工艺流程, but the charge distribution becomes uneven and threshold voltage range increases leading to sensing errors

Engineering Contradiction:

Improvecharge distribution uniformityVSAvoidsensing accuracy

Core Design Contradiction:

Manufacturing precisionVSReliability

Solution Approach 1:

The patent inverts the conventional fabrication sequence by performing ultraviolet treatment before annealing process. This reversal of process order resolves the technical contradiction: the ultraviolet treatment first creates initial charge distribution, and subsequent annealing process then uniformly redistributes these charges, achieving both uniform charge distribution and narrow threshold voltage range, thereby eliminating sensing errors while maintaining manufacturing precision

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The patent changes the temporal parameter (process sequence) from conventional (annealing then UV treatment) to inverted (UV treatment then annealing). This parameter change transforms the charge distribution outcome: UV treatment generates charges that are subsequently uniformly distributed by annealing, achieving homogeneous charge distribution and narrow threshold voltage range, which directly improves sensing accuracy without compromising manufacturing precision

Inventive Principle:

Principle #35Parameter changes

2Measurement precision

If conventional fabrication sequence is used, then process complexity remains standard, but threshold voltage distribution widens causing increased sensing errors

Engineering Contradiction:

Improvethreshold voltage measurement accuracyVSAvoidfabrication process sequence

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent applies inversion by reversing the annealing and UV treatment sequence. Although this changes the fabrication process sequence, the overall complexity remains comparable as both are standard semiconductor processing steps. The benefit is significant: the inverted sequence produces narrow threshold voltage distribution, directly improving measurement precision and reducing sensing errors without adding substantial process complexity

Inventive Principle:

Principle #13The other way round (Inversion)

3Reliability

If annealing is performed before ultraviolet treatment, then plasma effect issues occur during contact hole fabrication, but following conventional sequence increases threshold voltage range and reduces memory performance

Engineering Contradiction:

Improvememory performanceVSAvoidplasma effect-induced issues

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent applies preliminary action by performing ultraviolet treatment before annealing. The UV treatment preliminarily generates charges in the charge storage layer, and the subsequent annealing process then uniformly distributes these charges. This preliminary charge generation followed by uniform distribution resolves the plasma effect issues and achieves narrow threshold voltage range, thereby improving memory performance and reliability while mitigating harmful plasma effects

Inventive Principle:

Principle #10Preliminary action

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 reduces sensing errors and improves charge distribution, enhancing the memory's programming and erasing accuracy by stabilizing voltage levels and reducing the plasma effect-induced issues.

Implementation Method 1

performing a ultraviolet treatment after the fabrication of the passivation layer and contact pads

Methodology Applied

Scientific EffectPhotoelectric effect: Photoelectric Effect

Implementation Method 2

performing an annealing process thereafter

Methodology Applied

Scientific EffectThermal annealing: Annealing

Data Source

PatentUS7498228B2Method for fabricating SONOS a memory

Publication Date: 2009.03.03 UNITED MICROELECTRONICS CORP

AI summary

A method for fabricating a SONOS memory is disclosed. First, a semiconductor substrate is provided and a SONOS memory cell is formed on said semiconductor substrate. A passivation layer is deposited on the SONOS memory cell and a contact pad is formed on the passivation layer. Subsequently, an ultraviolet treatment is performed and an annealing process is conducted thereafter.