Maskless Lithography Using Negative Photoresist Material: Impact of UV Laser Intensity on the Cured Line Width

Mohammed, Mohammed Ziauddin; Mourad, Abdel‐Hamid I.; Khashan, Saud

doi:10.1007/s40516-018-0058-2

Cited by 7 publications

(2 citation statements)

References 10 publications

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“…Contrary to this advantage, the price of the mask is the main factor that reduces the interest in masked photolithography. In the maskless lithography, on the other hand [10], an extraordinary parameter called laser velocity (writing speed, mm/s) has an important role in determining the exposing process as the maskless lithography is like directly writing with a laser pen. Another advantage of the direct laser writer system is that it can be performed for patterning in different shapes without using any additional masks unlike the masked photolithography.…”

Section: Introductionmentioning

confidence: 99%

A Comparative Study on the Photoresist Patterning of Glass and Silicon With Microholes via Maskless Photolithography

GÜÇLÜER

Keleş

2022

Eurasian Journal of Science Engineering and Technology

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Maskless photolithography, a useful tool used in patterning the photoresist which acts as a mask prior to the actual etching process of substrate, has attracted attention mainly due to the taking advantage of reducing cost because of not requiring a preprepared mask and freedom in creating the desired pattern on any kind of substrate. In this study, we performed the positive photoresist patterning with microstructures on both glass and silicon substrates via maskless photolithography. Specifically, we examined the discrepancies between the transparent (glass) and reflective (silicon) substrates even though the photolithographic process has been carried out under the same conditions. Since the positive photoresist patterning was the subject of this study, we could successfully produce the microholes with almost circular shapes and properly placed in squarely packed on both substrates as confirmed by optical microscopy and profilometer mapping measurements. We observed additional rings around the holes when silicon was used as substrate while very clear microholes were obtained for glass. Besides, the number of the rings increased when the writing speed of laser (velocity) reduced. We claim that these important findings can be attributed to the standing wave effect phenomenon which results from the multiple reflections through the semi-transparent photoresist coated on the reflective surface of the polished silicon. In brief, we reveal an important conclusion, in this study, based on the differences in formation of the microholes only due to the substate preference while all the photolithographic process parameters are kept the same.

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Section: Introductionmentioning

confidence: 99%

A Comparative Study on the Photoresist Patterning of Glass and Silicon With Microholes via Maskless Photolithography

GÜÇLÜER

Keleş

2022

Eurasian Journal of Science Engineering and Technology

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“…In DLW, the desired geometry and accuracy of the micropattern is affected by multiple parameters such as the intensity of laser, motion accuracy of the fixture table, speed, focus thickness, substrate thickness and the type of photoresist used. In the past, attempts have been made to study the variation of line width with the change in exposure intensity of the laser and the speed with which it moves over the substrate [19,20]. A relatively stable line width of a micropattern was obtained simply by adjusting the intensity of the laser [21].…”

Section: Introductionmentioning

confidence: 99%

Optimization and characterization of direct UV laser writing system for microscale applications

Srikanth¹,

Dudala²,

Raut³

et al. 2020

J. Micromech. Microeng.

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Direct laser writing is a lithography technique for fabricating features in sub-micron dimensions. Major advantages of this technique are the elimination of mask, cost-effectiveness and design scalability. Patterns with different dimensions and geometries can be fabricated using this technique, which are greatly influenced by several laser parameters such as the intensity of the laser, speed of the stage (substrate), and focus level of the laser. To achieve high accuracy, the effects of the operative parameters on width are required to be mapped. In this work, the effect of various parameters, such as laser intensity, stage speed, and focus level (Z-axis movement), on the features of the micropatterns has been investigated. The laser intensity was varied from 25 000 W m−2 to 65 000 W m−2, and the stage speed was varied from 20 steps per minute to 200 steps per minute. The focus level was altered from the far limit of the Z-axis and incremented by a value of 0.1 mm. The patterns were created on glass substrates coated with negative dry film photoresist. The geometry of the obtained patterns was analyzed using optical microscopy and scanning electron microscopy. Subsequently, the statistical tools were employed to frame empirical relationships of the parameters with feature size as a response function. The construction of the efficient experimental combinations has been performed using design of experiments and the response values were analyzed using tools such as analysis of means and analysis of variance. Except knowing the significance of all the individual parameters, it was observed that the focus level highly influenced the feature size compared to the intensity of laser and stage speed. The applications of these devices in the fields of droplet based microfluidics and interdigitated electrodes for electrochemical sensing have also been discussed.

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Studying the impact of depth of focus on 3D profile of negative photoresist material: a simulation approach

et al. 2020

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For quality patterning of microstructures, it is essential that all process parameters are optimized to ensure well-developed 3D profile of the resist. Advances in direct laser lithography have provided maskless and rapid prototyping methods of manufacturing microstructures. Among all other process parameters, the quality of the patterned structure is critically affected by the depth of focus adjustments of the laser spot. In this study, a simulation approach is adopted and the LAB Module of GenISys lithography simulation software is implemented to determine the optimum depth of focus for negative photoresist material. Modeling and studying straight-line structure at different focusing depths at constant exposure dosages is carried out in this work. At the constant dosage of 45 mJ/cm 2 , the 15 µm depth of focus yields the best quality for the 3D resist profile.

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Maskless Lithography Using Negative Photoresist Material: Impact of UV Laser Intensity on the Cured Line Width

Cited by 7 publications

References 10 publications

A Comparative Study on the Photoresist Patterning of Glass and Silicon With Microholes via Maskless Photolithography

A Comparative Study on the Photoresist Patterning of Glass and Silicon With Microholes via Maskless Photolithography

Optimization and characterization of direct UV laser writing system for microscale applications

Studying the impact of depth of focus on 3D profile of negative photoresist material: a simulation approach

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