Photoresist Patterning With Field-Directed Acid Diffusion Control
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Solution Overview
Problem
In photolithography, the inaccurate control of line width roughness and resolution in the photoresist layer leads to device failure and yield loss due to random diffusion of acid generated by photoacid generators, resulting in undesired wiggling or roughness at the edge of the patterned photoresist layer.
Innovation Solution
Applying an electric or magnetic field during the pre- and/or post-exposure baking process to control the distribution and directionality of acid from the photoacid generator, thereby directing it to a predetermined region, and performing ion implantation to create a doped region that assists in enhancing the resolution and profile control of the photoresist layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If photolithography exposure process is used to form patterned photoresist layer, then components can be formed on chip, but line width roughness and resolution are poorly controlled due to random acid diffusion
Solution Approach 1:
An underlayer is introduced as an intermediary between the photoresist layer and the substrate. This underlayer acts as a mediator to capture and confine the acid generated by the photoacid generator, preventing its random diffusion into regions that should remain protected. The underlayer serves as a buffer zone that controls acid distribution and directs it to predetermined areas, thereby reducing line width roughness and improving manufacturing precision.
Solution Approach 2:
The patent modifies the chemical and physical parameters of the system by introducing an underlayer with specific properties (composition, thickness, acid affinity) that change how acid behaves during post-exposure baking. By adjusting parameters such as the underlayer material composition and the baking temperature profile, the acid diffusion pattern is controlled to reduce harmful random diffusion while maintaining desired patterning effects.
2Reliability
If photoacid generator is used to generate acid upon exposure, then solubility of photoresist is altered for pattern formation, but acid randomly diffuses to unprotected regions creating undesired roughness
Solution Approach 1:
The underlayer serves as a protective intermediary that intercepts acid before it can reach the photoresist layer in protected regions. During post-exposure baking, the underlayer captures the diffusing acid through its specific chemical properties, preventing the acid from laterally spreading into areas that should maintain their original solubility characteristics. This ensures that only the intended exposed regions undergo solubility changes, improving pattern formation accuracy.
Solution Approach 2:
The underlayer is designed with local quality variations or specific localized properties that enable it to selectively manage acid distribution. By creating regions of different acid affinity or thickness in the underlayer, the patent controls where acid accumulates and where it is blocked, ensuring that protected photoresist regions remain unaffected while exposed regions properly modify their solubility for accurate pattern formation.
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 effectively reduces line edge/width roughness, improves resolution, and enhances the accuracy of feature transfer to the target material, resulting in improved device yield and profile control with corner angles between 85 and 95 degrees and line width roughness less than 10 nm.
Implementation Method 1
The electromagnetic radiation may decompose the photoacid generator, which generates acid and results in a latent acid image in the resist resin
Implementation Method 2
After exposure, the substrate may be heated in a post-exposure bake process. During the post-exposure bake process, the acid generated by the photoacid generator reacts with the resist resin in the photoresist layer
Implementation Method 3
applying an electric field or a magnetic field while performing the post-exposure baking process or prior to exposure of the photoresist layer, and drifting photoacid from the photoresist layer into a predetermined portion of the underlayer under the first portion of the photoresist layer
Implementation Method 4
applying an electric field or a magnetic field while performing the post-exposure baking process or prior to exposure of the photoresist layer, and drifting photoacid from the photoresist layer into a predetermined portion of the underlayer
Implementation Method 5
performing an ion implantation process on the substrate to implant ions into a top layer exposed by the openings of the patterned photoresist layer to form a doped region in the top layer
Data Source
AI summary
A method for enhancing a photoresist profile control includes applying a photoresist layer comprising a photoacid generator on an underlayer disposed on a material layer, exposing a first portion of the photoresist layer unprotected by a photomask to light radiation in a lithographic exposure process, providing a thermal energy to the photoresist layer in a post-exposure baking process, applying an electric field or a magnetic field while performing the post-exposure baking process, and drifting photoacid from the photoresist layer to a predetermined portion of the underlayer under the first portion of the photoresist layer.