Block Copolymer Pattern Formation via Secondary Electron Irradiation
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Solution Overview
Problem
Existing methods for forming patterns with self-assembled block copolymer layers face challenges in selectively etching the second region with respect to the first region using oxygen plasma, as described in Patent Documents 1 and 2, due to difficulties in achieving the necessary etching conditions.
Innovation Solution
A pattern forming method involving the formation of a block copolymer layer with a capacitively coupled plasma processing apparatus, where the second region is etched partway in the thickness direction, and secondary electrons are irradiated to further cure the first region, allowing for selective etching and removal of the second region.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If oxygen plasma etching is performed on a block copolymer layer with phase-separated first and second regions, then the second region can be removed, but selective etching with respect to the first region cannot be achieved
Solution Approach 1:
The patent applies preliminary action by performing a first etching process to partially remove the second region before the main etching process. This preliminary etching creates a height difference between the first and second regions, which then enables selective etching in the subsequent process using oxygen plasma. The preliminary action prepares the surface topology to facilitate the desired selective removal.
Solution Approach 2:
The patent changes etching parameters by using different etching conditions for the preliminary etching step versus the main selective etching step. The first etching process uses parameters optimized for removing the second region, while the second process uses oxygen plasma with parameters that exploit the height difference created to achieve high selectivity. This parameter change enables the resolution of the contradiction between removing the second region and preserving the first region.
2Length of moving object
If the second region is completely removed to achieve the desired pattern, then the pattern dimension can be reduced, but the first region cannot be protected from etching
Solution Approach 1:
The preliminary etching step creates a height difference that acts as a protective mechanism for the first region during the main etching process. By partially removing the second region first, the patent establishes a topographic difference that prevents the oxygen plasma from uniformly etching both regions, thus protecting the first region while enabling complete removal of the second region to achieve the desired small pattern dimensions.
Solution Approach 2:
The patent applies local quality by creating a height difference between different regions of the block copolymer layer. The first region and second region are treated differently in terms of their height/position after the preliminary etching, which then allows the oxygen plasma to selectively interact with each region. This local differentiation in height enables the second region to be completely removed while the first region remains protected, achieving both small pattern dimensions and high pattern fidelity.
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 method enables selective etching and removal of the second region with respect to the first region, achieving a recessed surface that enhances the curing of the first region and allows for precise pattern formation suitable for miniaturized device manufacturing.
Implementation Method 1
supplying a processing gas for generating cations into the plasma processing apparatus and exciting the processing gas to generate the cations
Implementation Method 2
generating secondary electrons from an upper electrode of the plasma processing apparatus by applying a negative DC voltage to the upper electrode such that the cations collide with the upper electrode, and irradiating the secondary electrons onto the target object
Implementation Method 3
a heat-treatment (annealing) is performed in order to phase-separate the polymer block components A and B by themselves. Thus, an organized pattern including a first region containing the polymer block component A and a second region containing the second polymer block component B can be obtained
Implementation Method 4
etching the second region partway in a thickness direction of the second region in a capacitively coupled plasma processing apparatus
Data Source
Figure 1
Figure 2A~2D
Figure 3A~3B
AI summary
A pattern is formed on an underlying layer of a target object by a pattern forming method. The pattern forming method includes (a) forming a block copolymer layer, which includes a first polymer and a second polymer and is configured to be self-assembled, on the underlying layer; (b) processing the target object to form a first region containing the first polymer and a second region containing the second polymer in the block copolymer layer; (c) etching the second region partway in a thickness direction of the second region in a capacitively coupled plasma processing apparatus after the processing of the target object; (d) generating secondary electrons from an upper electrode of the plasma processing apparatus by applying a negative DC voltage to the upper electrode and irradiating the secondary electrons onto the target object, after the etching of the second region; and (e) additionally etching the second region in the plasma processing apparatus after the irradiating of the secondary electrons onto the target object.