Organometallic EUV Mandrel for Spacer Pattern CD Control
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Solution Overview
Problem
The semiconductor industry faces challenges in improving critical dimension control during the lithography process for patterned features, as existing mandrels do not adequately address the need for precise geometry control and risk collapse of spacer elements, while also minimizing consumption of underlying layers during etching.
Innovation Solution
A mandrel composition incorporating an organometallic material that absorbs radiation and a photoacid generator is used, allowing for reduced critical dimension of patterned features, lower mandrel thickness to prevent collapse, and high etching selectivity relative to the underlying layer, enabling the mandrel to function as either a positive or negative tone resist in the lithography process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If existing mandrels are used in lithography, then the lithography process can be performed, but critical dimension control is insufficient and patterned features may collapse
Solution Approach 1:
The mandrel is formed as a composite structure comprising a first material layer and a second material layer with different etch selectivities. The first material layer provides structural support to prevent collapse, while the second material layer enables precise pattern transfer. This composite approach allows the mandrel to simultaneously achieve both mechanical stability and manufacturing precision.
Solution Approach 2:
The invention changes the material parameters of the mandrel by selecting materials with specific etch selectivity ratios. The second material layer is chosen to have significantly higher etch selectivity than the first material layer, allowing the patterned features to be precisely defined while the first material layer maintains structural integrity during the etching process.
2Manufacturing precision
If mandrel thickness is reduced to improve critical dimension control, then pattern precision improves, but mandrel collapse risk increases
Solution Approach 1:
The composite mandrel structure with two material layers of different etch selectivities enables the use of thinner overall mandrel structures for improved precision while the first material layer provides the necessary structural support. The differential etching allows precise pattern definition without compromising the structural strength needed to prevent collapse.
Solution Approach 2:
Different regions of the mandrel have different material properties - the first material layer provides structural strength in regions requiring support, while the second material layer provides precise pattern definition in regions requiring etching. This local differentiation of material quality allows simultaneous optimization of both precision and strength.
3Loss of substance
If etching selectivity is increased to minimize underlying layer consumption, then underlying layer preservation improves, but mandrel material selection becomes more constrained
Solution Approach 1:
The composite mandrel structure with two material layers provides different etch selectivities for different underlying layers. The first material layer can be selected for high selectivity against semiconductor substrates, while the second material layer provides selectivity against dielectric layers. This composite approach expands material selection flexibility rather than constraining it.
Solution Approach 2:
The mandrel structure serves multiple functions simultaneously - the first material layer provides structural support and protection for semiconductor substrates, while the second material layer enables precise pattern transfer and protection for dielectric layers. This multi-functionality makes the mandrel system adaptable to various underlying layers and process conditions.
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 solution enhances critical dimension control, reduces the risk of mandrel collapse, and minimizes underlying layer consumption during etching, thereby improving the accuracy and efficiency of the lithography process.
Implementation Method 1
A mandrel composition incorporating an organometallic material that absorbs radiation
Implementation Method 2
A mandrel composition incorporating an organometallic material that absorbs radiation and a photoacid generator
Data Source
AI summary
A method includes depositing a photoresist layer over a target layer, the photoresist layer comprising an organometallic material; exposing the photoresist layer to an extreme ultraviolet (EUV) radiation; developing the exposed photoresist layer to form a photoresist pattern; forming a spacer on a sidewall of the photoresist pattern; removing the photoresist pattern; after removing the photoresist pattern, patterning the target layer through the spacer.