Double Patterning Photoresist for High Density Pillar Structures
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current semiconductor manufacturing techniques, such as double patterning and sidewall spacers, fail to effectively create two-dimensional arrays of regularly spaced pillars due to limitations in photolithography resolution and the resulting formation of cylindrical annuli instead of solid pillars.
Innovation Solution
A method involving a double patterning process where a first photoresist pattern is used to form spaced apart features, followed by a second photoresist pattern that covers edge portions of these features, allowing for the etching of edge portions to create smaller masking features that can be used to form dense pillar arrays or pattern underlying layers into pillar structures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If double patterning is used to extend pitch beyond photolithography limits, then structures with pitch less than 80 nm can be fabricated, but the process complexity increases significantly
Solution Approach 1:
The patent segments the patterning process into two distinct steps: first forming a template pattern with initial photoresist features, then forming sidewall spacers on these templates. This segmentation allows the final pattern pitch to be twice the original photoresist feature pitch, effectively extending the resolution capability of the photolithography tool while managing process complexity through systematic division of steps
Solution Approach 2:
The patent transitions from two-dimensional planar patterning to three-dimensional sidewall spacer formation. By depositing conformal spacer material on the vertical sidewalls of the template features and then performing anisotropic etching, the method creates patterns in the vertical dimension that translate to enhanced horizontal resolution, achieving pitch extension without proportionally increasing planar process complexity
2Manufacturing precision
If sidewall spacer method is used to create patterns, then pitch is divided by two, but cylindrical annuli are produced instead of solid pillars for two-dimensional pillar arrays
Solution Approach 1:
The patent performs preliminary actions by first forming the template pattern with photoresist features, then depositing spacer material and performing selective removal to create solid core structures before final etching. This preliminary formation of solid cores within the spacer structures ensures that the final etched features are solid pillars rather than hollow annuli, while still achieving the pitch division benefit of sidewall spacers
Solution Approach 2:
The patent uses composite material structures combining photoresist templates with deposited spacer materials (such as silicon nitride or silicon oxide). This composite approach allows the template to define the core position while the spacer material forms the surrounding structure, enabling solid pillar formation through selective etching of the template material while preserving the spacer material as the final pillar structure
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 enables the formation of high-density pillar arrays with pitches less than 100 nm, overcoming the limitations of existing techniques by achieving smaller feature sizes and maintaining the integrity of pillar shapes, suitable for advanced memory devices.
Implementation Method 1
forming a first photoresist layer over an underlying layer, patterning the first photoresist layer into a first photoresist pattern
Implementation Method 2
A first photoresist layer is then formed and patterned into a first photoresist pattern having spaced apart first photoresist features
Data Source
AI summary
A method of making a semiconductor device includes forming a first photoresist layer over an underlying layer, patterning the first photoresist layer into a first photoresist pattern, wherein the first photoresist pattern comprises a plurality of spaced apart first photoresist features located over the underlying layer, and etching the underlying layer using the first photoresist pattern as a mask to form a plurality of first spaced apart features. The method further includes removing the first photoresist pattern, forming a second photoresist layer over the plurality of first spaced apart features, and patterning the second photoresist layer into a second photoresist pattern, wherein the second photoresist pattern comprises a plurality of second photoresist features covering edge portions of the plurality of first spaced apart features. The method also includes etching exposed portions of the plurality of first spaced apart features using the second photoresist pattern as a mask, such that a plurality of spaced apart edge portions of the plurality of first spaced apart features remain, and removing the second photoresist pattern.