EUV Lithography REMA Part for Black Border Effect
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Solution Overview
Problem
In EUV lithography processes, the critical dimension (CD) uniformity of patterns on semiconductor wafers is degraded due to the 'black border effect,' where EUV rays are reflected from the light absorption layer in mirror masks, causing multiple exposures and non-uniformity at the edges of field regions.
Innovation Solution
A lithography process is implemented using a reticle masking (REMA) part with a REMA open region, where the edge boundary of the REMA open region is positioned on a scribe lane between chip regions, preventing unwanted EUV ray reflection and ensuring uniform exposure during sequential exposure steps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a light absorption layer is coated on the black region of the mirror mask to prevent EUV ray reflection, then the CD uniformity should be improved, but the light absorption layer cannot completely absorb the EUV rays and still reflects a small portion causing the black border effect
Solution Approach 1:
A REMA part is introduced as an intermediary component between the illumination optical system and the mirror reticle. This REMA part has a REMA open region that is positioned to overlap with the chip region on the wafer, allowing controlled EUV ray transmission while blocking rays that would cause the black border effect at field region edges.
Solution Approach 2:
The REMA part is designed with spatially varying properties: the REMA open region allows EUV transmission over the chip region, while the surrounding areas block rays. This local differentiation of light transmission properties addresses the black border effect specifically at critical regions without affecting the overall exposure quality.
2Productivity
If the mirror optical system is used to transfer pattern images onto the wafer, then the lithography process can be performed with EUV rays, but the critical dimension uniformity is degraded at the edges of field regions due to multiple exposures
Solution Approach 1:
The REMA part serves as a mediator that modifies the EUV ray path in the mirror optical system. By positioning the REMA open region to overlap with the chip region and controlling its boundaries to extend into scribe lane regions, it prevents EUV rays from reaching black regions that would cause multiple exposures at field edges.
Solution Approach 2:
The REMA part is positioned in advance before exposure to pre-block the paths of EUV rays that would otherwise reflect from black regions and cause multiple exposures. This preliminary blocking action prevents the black border effect before it occurs during the exposure process.
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 approach effectively minimizes the black border effect, leading to improved CD uniformity and reduced over-exposure of chip regions, enhancing the quality of semiconductor device manufacturing.
Implementation Method 1
the light absorption layer may not completely absorb the EUV rays which are irradiated thereon
Implementation Method 2
a lithography apparatus using the extreme ultraviolet (EUV) ray may include a mirror optical system
Data Source
AI summary
Lithography processes are provided. The lithography process includes installing a reticle masking (REMA) part having a REMA open region in a lithography apparatus, loading a reticle including at least one reticle chip region in which circuit patterns are disposed into the lithography apparatus, and sequentially exposing a first wafer field, which includes a first chip region corresponding to the reticle chip region, and a second wafer field, which includes a second chip region corresponding to the reticle chip region, of a wafer to rays using the reticle and the REMA part to transfer images of the circuit patterns onto the wafer. An edge boundary of the REMA open region transferred on the first wafer field is located on a scribe lane region between the first and second chip regions while the first wafer field is exposed. Methods of manufacturing a semiconductor device using the lithography process are also provided.