Single step direct-write photomask made from bimetallic Bi/In thermal resist

Chapman, Glenn H.; Tu, Richard Yuqiang

doi:10.1117/12.479415

Cited by 12 publications

(10 citation statements)

References 9 publications

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“…The applications of Bi/In laser converted films were reported in our earlier papers [17,18]. In that research Bi/In oxide film was shown to be a new kind of inorganic thermal resists with low energy exposure requirements due to its low eutectic melting point.…”

Section: Applications Of Patterned Sn/in Oxide Filmsmentioning

confidence: 96%

“…The table was moved in a raster scan motion along X direction at a constant speed while there is a constant incremental step along the Y direction. Different designed patterns can be made by writing computer control scripts or by using a specialized mask making program which takes 8-bit gray-scale bitmap created by common drawing software as input files [6]. Figure 1 illustrates the picture of the laser exposure system.…”

Section: The Laser Exposure Set Upmentioning

confidence: 99%

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Laser direct write patterned indium tin oxide films for photomasks and anisotropic resist applications

Peng

Chapman

2004

Photonics North 2004: Photonic Applications in Astronomy, Biomedicine, Imaging, Materials Processing, and Education

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A laser direct write process has been developed for turning patterned bimetallic Sn/In film into a indium tin oxide layer. Sn over In films (15-120nm thick) with a 1:10 thickness ratio were deposited by DC sputtering. An argon laser beam (0.1 -0.9 W, spot size: 2 micron, scan speed: 1 cm/s) exposes the film into patterns. These Sn/In films' optical absorption changed from 3 OD at deposition to 0.24 OD after exposure (at 356 nm). XRD, SEM, EDX, and Auger have been used to investigate the film's microstructure and composition suggesting ITO like characteristics. XRD indicated a preferred In 2 O 3 (222) orientation which is similar to ITO films deposited by other methods. Four-point probe tests showed a converted film resistivity of 0.26x10 -3 to 9.7x10 -3 ohm-cm depending on the laser power and Sn concentration. Hall tests indicated that the bulk carrier concentration was in the range of 10 18 to 10 20 cm -3 . Developed in a wet HCl: H 2 O 2 : H 2 O =1:1:48 solution removes unexposed Sn/In leaving patterned ITO films created at much lower laser power levels than needed for ablative patterning of ITO. Developed films are also resistant to KOH anisotropic etching at a 1:700 ratio producing <111> trenches in Si (100). The large change in optical density means Sn/In films can be used as a material of the direct write photomasks.

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Section: Applications Of Patterned Sn/in Oxide Filmsmentioning

confidence: 96%

Section: The Laser Exposure Set Upmentioning

confidence: 99%

Laser direct write patterned indium tin oxide films for photomasks and anisotropic resist applications

Peng

Chapman

2004

Photonics North 2004: Photonic Applications in Astronomy, Biomedicine, Imaging, Materials Processing, and Education

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“…Based on the results shown in Figure 6 where the optical density changes from ~3OD to 0.26OD at 365 nm (I-line) after over 600mW laser exposure, we have successfully created binary photomasks on bimetallic films [15]. The four pictures in Figure 8 show a mask that is made with 40/40 nm Bi/In on quartz substrate.…”

Section: Creating Binary Masks From Bimetallic Filmsmentioning

confidence: 97%

“…The optical spectrum was measured before and after the shelf test. The transmission rate barely changed and the optical property is stable as is required for photomasks [15]. …”

Section: Optical Properties Of Exposed Filmsmentioning

confidence: 98%

“…This is ideal to make direct-write binary photomasks which require ~ 3 OD for unexposed area and < 0.25 OD for exposed area. Previous investigation [15] shows that annealing the Bi/In samples at 50 to 90°C for a period of time in the air prior to laser exposure helps reduce the optical density of the exposed area. With this method, we successfully made photomasks for i-line (365 nm) with 2.9OD for unexposed area and 0.26OD for exposed area.…”

Section: Optical Properties Of Exposed Filmsmentioning

confidence: 99%

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Creating direct-write gray-scale photomasks with bimetallic thin film thermal resists

Chapman

Dykes

et al. 2003

SPIE Proceedings

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New types of analog gray-scale laser direct-write masks have been created using bimetallic thermal resists and a directwrite laser process. Bimetallic resists consist of two layers of thin films, eg. Bi over In or Sn over In, which react to form a low temperature alloy when a laser raises the films above the eutectic temperature. Depending on the exposure energy, resulting alloyed layers appear to become oxides, causing a change of absorption at 365nm from >3OD to <0.3OD. The thermal resists show near wavelength invariance from IR to UV. The Sn/In films, each layer ~40 nm thick, were DCsputtered onto glass slides or quartz substrates. To make gray-scale photomasks the samples were placed on a computercontrolled high accuracy X-Y table. A bitmap gray-scale pattern was raster-scanned with a CW Argon laser (514 nm) beam. An optical shutter controlled the actual laser power applied onto the thermal resist film according to the gray-scale value. When exposed to a laser beam greater than 0.6 W, the Sn/In film became nearly transparent (0.22OD) at I-line (365nm) wavelength. Sn/In and Bi/In photomasks have been used together with a standard mask aligner to successfully pattern Shipley SPR2FX-1.3 photoresist. CF 4 /O 2 plasma etching has been used to transfer the three-dimensional pattern to SiO 2 and Si substrates. Also a 160 beam laser diode thermal imaging tool was used to create BiIn direct-write binary masks.

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Fabrication of Flexible Binary Amplitude Masks for Patterning on Highly Curved Surfaces

Bowen

Nuzzo

2009

Adv Funct Materials

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This paper describes soft lithography methods that expand current fabrication capabilities by enabling high‐throughput patterning on nonplanar substrates. These techniques exploit optically dense elastomeric mask elements embedded in a transparent poly(dimethylsiloxane) (PDMS) matrix by vacuum‐assisted microfluidic patterning, UV–ozone‐mediated irreversible sealing, and chemical etching. These protocols provide highly flexible photomasks exhibiting either positive‐ or negative‐image contrasts, which serve as amplitude masks for large‐area photolithographic patterning on a variety of curved (and planar) surfaces. When patterning on cylindrical surfaces, the developed masks do not experience significant pattern distortions. For substrates with 3D curvatures/geometries, however, the PDMS mask must undergo relatively large strains in order to make conformal contact. The new methods described in this report provide planar masks that can be patterned to compliantly compensate for both the displacements and distortions of features that result from stretching the mask to span the 3D geometry. To demonstrate this, a distortion‐corrected grid pattern mask was fabricated and used in conjunction with a homemade inflation device to pattern an electrode mesh on a glass hemisphere with predictable registration and distortion compensation. The showcased mask fabrication processes are compatible with a broad range of substrates, illustrating the potential for development of complex lithographic patterns for a variety of applications in the realm of curved electronics (i.e., synthetic retinal implants and curved LED arrays) and wide field‐of‐view optics.

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Single step direct-write photomask made from bimetallic Bi/In thermal resist

Cited by 12 publications

References 9 publications

Laser direct write patterned indium tin oxide films for photomasks and anisotropic resist applications

Laser direct write patterned indium tin oxide films for photomasks and anisotropic resist applications

Creating direct-write gray-scale photomasks with bimetallic thin film thermal resists

Fabrication of Flexible Binary Amplitude Masks for Patterning on Highly Curved Surfaces

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