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This article teaches that a photomask utilizing opacified photoresist images can be easily and cheaply made with a very simple mask fabrication process.
English (United States)
This text was extracted from a PDF file.
This is the abbreviated version, containing approximately
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Photomask Utilizing Opacified Photoresist Images
This article teaches that a photomask utilizing opacified photoresist images
can be easily and cheaply made with a very simple mask fabrication process.
A coating of photoresist, normally transparent to ultraviolet radiation, is
deposited on a glass substrate and exposed and developed using normal
techniques. The images created in the coating of the photoresist are than made
opaque, thus forming a mask suitable for direct photo fabrication techniques
used in semiconductor processing.
The process for accomplishing this comprises the following steps: A clean
glass mask substrate has a photoresist coating deposited thereon. This coating
is then exposed to the desired image and developed using standard techniques.
Once the image has been fully developed, it is opacified by soaking the
photoresist-coated glass mask in a saturated solution of potassium
permanganate (KMnO(4)) or in a saturated solution of ferric chloride (FeCl) or in
sulfuric acid (H(2)SO(4)). Once the im age has been soaked in a saturated
solution for a period of 10 to 20 minutes, the opacified mask is visually checked
and inspected for dimensional accuracy, after which the unit can be utilized in the
normal photomask methods in semiconductor processes.
These chemical processes provide shorter process cycles and turnaround
time without the use of costly equipment. Additionally, no potential wafer
contamination remains in the images or on the mask. Furthe...