Post Baking Apparatus Vertical Field Control
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Solution Overview
Problem
In the photolithography process, acids and secondary electrons generated from exposed regions of the photoresist film during the post baking process diffuse into non-exposed regions, leading to line roughness and pattern distortion in semiconductor devices.
Innovation Solution
A post baking apparatus with a baking chamber that applies an electric field or magnetic field vertically to control the diffusion of acids and secondary electrons, using a combination of lower and upper electrodes and a coil to form electromagnetic fields, which suppress the horizontal diffusion of these species, and a controller to manage the heating and field operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If heating is applied to the exposed photoresist film during post baking, then the baking process is effective, but acids and secondary electrons diffuse into non-exposed regions causing line roughness
Solution Approach 1:
An electric field or magnetic field is applied to the photoresist film before and during the heating process to prevent the diffusion of acids and secondary electrons. This preliminary protective action counteracts the harmful diffusion effect that would otherwise occur during thermal baking, allowing effective heating while maintaining pattern precision.
Solution Approach 2:
An electric field or magnetic field is introduced as an intermediary mechanism between the heating process and the photoresist film. This field acts as a mediator that controls the movement of charged particles (acids and secondary electrons), enabling thermal processing without the harmful side effects of particle diffusion.
2Manufacturing precision
If an electric field or magnetic field is applied to control diffusion, then line roughness is reduced, but device complexity increases
Solution Approach 1:
The electrode structure serves multiple functions: it applies the electric field to control particle diffusion, it heats the photoresist film through resistive heating, and it provides structural support within the baking chamber. This multi-functionality reduces the need for separate components, thereby limiting the increase in device complexity.
Solution Approach 2:
The patent replaces complex mechanical systems for controlling particle diffusion with electromagnetic fields. Instead of using physical barriers or mechanical manipulation methods, the invention uses electric or magnetic fields to achieve the same control objective with simpler apparatus 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
Effectively prevents the diffusion of acids and secondary electrons into non-exposed regions, thereby improving the line roughness and accuracy of the photoresist pattern, ensuring precise pattern formation in semiconductor devices.
Implementation Method 1
a lower heater in the baking chamber under the substrate to heat the exposed photoresist film
Implementation Method 2
a lower electrode under the lower heater, an upper electrode over the substrate to form an electric field from the lower electrode to the upper electrode along a vertical direction
Implementation Method 3
a coil on an inner sidewall of the baking chamber to form a magnetic field from the upper electrode to the lower electrode along the vertical direction
Data Source
AI summary
A post baking apparatus comprising a baking chamber configured to receive a substrate with an exposed photoresist film, a lower heater in the baking chamber under the substrate to heat the exposed photoresist film, an applier applying an electric field or a magnetic field to the exposed photoresist film along a vertical direction, which is substantially perpendicular to an upper surface of the exposed photoresist film, to control diffusions of an acid or a secondary electron, which are generated from the exposed photoresist film, along a horizontal direction, and a controller configured to control an operation of the applier.