Mandrel Openings for Sidewall Spacer Deformation Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The formation of wide conductive lines in close proximity to narrow bit lines in memory arrays is challenging due to stress-induced deformation of sidewall spacers, which can lead to defects and shorting of bit lines during the patterning process.
Innovation Solution
The use of mandrels with strategically placed openings to reduce deformation of sidewall spacers, where the openings are arranged to maintain a predetermined distance from the mandrel sides, allowing for the formation of wide conductive lines without significantly affecting adjacent bit lines, using a process that includes forming a sacrificial layer, patterning it into strips, depositing sidewall spacers, and patterning underlying layers accordingly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If wide mandrels are used to form wide conductive lines, then the conductive line width is increased, but sidewall spacer deformation occurs due to stress
Solution Approach 1:
The wide mandrel is segmented by introducing openings that divide it into multiple narrower sections. This segmentation reduces the stress-induced deformation of sidewall spacers while maintaining the overall wide conductive line structure. The openings create multiple smaller mandrel sections that generate less stress on adjacent sidewall spacers compared to a continuous wide mandrel.
Solution Approach 2:
The mandrel structure is modified locally by adding openings at specific positions rather than uniformly throughout. The openings are strategically placed to reduce stress in critical areas where sidewall spacers are formed, while maintaining the wide conductive line width where needed. This local modification approach allows the mandrel to have different properties in different regions.
2Reliability
If wide conductive lines are formed close to narrow bit lines, then connectivity is improved, but bit line defects and shorting occur due to stress-induced sidewall spacer deformation
Solution Approach 1:
The wide mandrel is divided into segments by openings, reducing the stress footprint that affects adjacent narrow bit lines. This segmentation prevents stress-induced deformation of sidewall spacers associated with bit lines, thereby preventing defects and shorting while maintaining the wide conductive line's connectivity function.
Solution Approach 2:
Material is extracted from the continuous wide mandrel by creating openings, removing the stress-generating portion that would otherwise deform adjacent sidewall spacers. This extraction of material from critical stress zones allows the wide conductive line to maintain connectivity without harming neighboring bit lines.
3Manufacturing precision
If openings are added to mandrels to reduce stress, then sidewall spacer deformation is minimized, but mandrel structural integrity may be compromised
Solution Approach 1:
Openings are strategically placed in specific locations on the mandrel where stress reduction is most beneficial for sidewall spacer formation, while maintaining sufficient material in other areas to preserve overall mandrel structural integrity. The openings are positioned to create the necessary stress relief zones without compromising the mandrel's ability to maintain its shape during processing.
Data Source
AI summary
Wide and narrow mandrels that are used to form sidewall spacers for patterning are formed in a sacrificial layer with openings in wide mandrels near sides of the wide mandrels. Sidewall spacers are formed on the sides of mandrels and the sacrificial layer is removed. The sidewall spacers are then used for patterning of underlying layers.