Lithography Sidewall Morphology Control via Mask Gradient
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Solution Overview
Problem
Current lithography processes struggle to define sidewall morphology with specific inclination angles, particularly angles less than 90 degrees, which is necessary for certain semiconductor device processes.
Innovation Solution
A lithography process method involving a mask with a side face pattern structure that allows exposure light intensity to gradually change, enabling the formation of lithography patterns with inclined sidewalls through exposure, development, and post-baking processes, where the height of the sidewall varies with light intensity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a conventional lithography mask with uniform thickness is used, then the exposure process is simple and fast, but the sidewall inclination angle cannot be controlled and is always close to 90 degrees
Solution Approach 1:
The mask is designed with different local properties: the central region has uniform thickness for standard exposure, while the peripheral region incorporates a gradient thickness structure. This local differentiation allows the sidewall inclination angle to be controlled in specific areas without affecting the entire mask, resolving the contradiction between precision control and device complexity.
Solution Approach 2:
The invention transitions from a two-dimensional uniform mask structure to a three-dimensional gradient thickness structure. By adding the thickness dimension variation, the mask can control sidewall inclination angles while maintaining structural feasibility, thus improving manufacturing precision without excessive complexity increase.
2Manufacturing precision
If a mask with gradient thickness structure is used to control sidewall morphology, then the sidewall inclination angle can be precisely controlled, but the exposure process time increases and process complexity increases
Solution Approach 1:
The gradient thickness mask is divided into multiple thickness zones (first thickness, second thickness, third thickness) with distinct functions. The first thickness region provides standard exposure, the second provides gradient exposure for sidewall control, and the third provides additional shielding. This segmentation allows selective exposure of different regions, reducing overall process time while maintaining precision.
Solution Approach 2:
The gradient thickness structure is pre-designed and fabricated into the mask before the lithography process. This preliminary action embeds the sidewall control function directly into the mask structure, eliminating the need for additional post-processing steps to achieve the desired sidewall morphology, thus reducing total process time.
3Manufacturing precision
If the mask gradient structure covers the entire mask area, then sidewall control is comprehensive, but the useful exposure area and production efficiency are reduced
Solution Approach 1:
The gradient thickness structure is applied locally only to the peripheral regions where sidewall control is needed, while the central region maintains uniform thickness for high-speed standard exposure. This local application ensures comprehensive sidewall control where required without sacrificing the productivity of the main exposure area.
Solution Approach 2:
The mask is segmented into functional zones: a central uniform thickness region for high-productivity standard lithography, and peripheral gradient thickness regions for specialized sidewall control applications. This segmentation allows the system to switch between high-speed production mode and precision sidewall control mode as needed, optimizing both productivity and precision.
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 defines sidewall morphology with controlled inclination angles, facilitating the formation of lithography patterns with desired gradients, enhancing the precision of semiconductor manufacturing.
Implementation Method 1
the mask side face pattern structure having a structure that enables an exposure light intensity to gradually change, wherein in an area of a larger exposure light intensity, the height of the sidewall of the lithography pattern is smaller, and in an area of a smaller exposure light intensity, the height of the sidewall of the lithography pattern is larger
Data Source
AI summary
The present disclosure discloses a lithography process method for defining sidewall morphology of a lithography pattern, comprising: Step 1: designing a mask, wherein a mask pattern is formed on the mask, the mask pattern being used to define a lithography pattern; the lithography pattern has a sidewall, and a mask side face pattern structure that defines sidewall morphology of the lithography pattern is provided on the mask pattern, the mask side face pattern structure having a structure that enables an exposure light intensity to gradually change; Step 2: coating a to-be-exposed substrate with a photoresist; Step 3: exposing the photoresist by using the mask, and then performing development to form the lithography pattern; and Step 4: performing post-baking. The present disclosure can define the sidewall morphology of a lithography pattern, facilitating formation of a lithography pattern sidewall with an inclined side face.