Bilayer lift-off process for aluminum metallization

Wilson, Thomas E.; Korolev, K.A.; Crow, Nathaniel

doi:10.1117/1.jmm.14.1.014501

Cited by 13 publications

(9 citation statements)

References 12 publications

(14 reference statements)

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“…In order to achieve the desired undercut pro le, various materials with different thicknesses and dissolution rates (such as LOR10B, PMGI sf3, and PMGI sf6) were investigated. Brie y, by implementing a second cycle of a curing step at a temperature higher than the photoresist (i.e., AZ) glass transition temperature (T g ) and lower than that of the dissolved layer (120 o C for 1 min), as proposed by Wilson et al (2015) (62), we could control the dissolution rate and the desired undercut pro le. Figure 3e-h.…”

Section: Dense Gold Microelectrode On Su8: Strong Attachment High Res...mentioning

confidence: 99%

Fabrication of a 3D high-resolution implant for neural stimulation - challenges and solutions

Shpun

Farah

Chemla

et al. 2022

Preprint

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Background - Tissue-integrated micro-electronic devices for neural stimulation hold a great potential in restoring the functionality of degenerated organs, specifically, retinal prostheses, which are aimed at vision restoration. The fabrication process of 3D polymer-metal devices with high resolution and a high aspect-ratio (AR) is very complex and faces many challenges that impair its functionality. Approach - Here we describe the optimization of the fabrication process of a bio-functionalized 3D high-resolution 1mm circular subretinal implant composed of SU-8 polymer integrated with dense gold microelectrodes (23µm pitch) passivated with 3D micro-well-like structures (20µm diameter, 3µm resolution). To this end, a nickel (Ni) evaporated silicon (Si) wafer was sequentially spin-coated with SU-8 and photolithographed layer-by-layer, with a sharp electrode formation achieved through a two-step bi-layer lift-off process using LOR/AZ, followed by Cr/Au thin-layer sputter deposition to increase the adhesion. Next, the device was released by overnight Ni wet-etching using nitric acid, after which it was bio-functionalized with N2 plasma treatment and the addition of the bio-adhesion molecule arginine-glycine-aspartic acid (RGD). Main results - In-vitro and in-vivo investigations, including SEM and FIB cross section examinations, revealed a good structural design, as well as a good integration of the device in the rat sub-retinal space and cell migration into the wells. The reported process and optimization steps described here in detail can aid in the design and fabrication of similar neural implants. Conclusions - The reported process and optimization steps described here in detail can aid in the design and fabrication of retinal prosthetic devices or similar neural implants.

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Section: Dense Gold Microelectrode On Su8: Strong Attachment High Res...mentioning

confidence: 99%

Fabrication of a 3D high-resolution implant for neural stimulation - challenges and solutions

Shpun

Farah

Chemla

et al. 2022

Preprint

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“…The LOR (LOR-15A, MicroChem Corp.) containing polyaliphatic imide copolymer dissolved in propylene glycol monomethyl ether has a high etching rate against developer and has been widely used in lift-off processes. 21) Under optimum process conditions for development with the developer of FHD-5, a FH6400 floating bridge was created by the selective removal of the underlying LOR [Fig. 2(c)].…”

Section: Fabrication Of Fpe Igzo Multi-gated Tftsmentioning

confidence: 99%

A novel photoresist-based film-profile engineering scheme for fabricating double-gated, recess-channel IGZO thin-film transistors

Huang¹,

Peng²,

Meng³

et al. 2020

Jpn. J. Appl. Phys.

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We reported an experimental fabrication of double-gated (DG) thin-film transistor (TFT) with IGZO recess-channel using a designer photoresist-based thin-film profile engineering approach. In this approach, an organic shadow mask of photoresist (PR) was formed over a p+-Si wafer that was encapsulated by an oxide layer. The lithographically-patterned PR layer is an effective mask for shadowing reactive species during the subsequent deposition steps of IGZO and Aluminum, enabling the formation of IGZO recess-channel and discrete Al source/drain pads at room-temperature. The top-gate or DG configurations with the Si substrate serving as the bottom-gate were investigated. The fabricated DG TFTs show significant improvements in both ION and IOFF as compared with single-gated TFTs. The proposed process scheme is readily applicable to the back-end-of-line of a chip. This work demonstrates the feasibility of IGZO recess-channel TFTs in various gated configurations, enabling a building block for emerging functional devices for More-than-Moore applications.

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“…A silicon dioxide material is directly deposited onto a fused silica substrate by the Plasma-enhanced chemical vapor deposition (PECVD) 19 method followed by a bilayer liftoff. 20,21 We can fabricate a 16-level DOE with four iterations of the liftoff process by using binarization advantage. We can thoroughly eliminate the etching and nanoimprinting steps with the proposed additive fabrication method.…”

Section: Introductionmentioning

confidence: 99%

Additive diffractive optical elements fabrication by PECVP deposition of SiO2 and lift-off process

Amata,

Fu,

Heidrich

2023

Digital Optical Technologies 2023

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Diffractive optical elements (DOEs) gradually start replacing traditional refractive optics in many applications. The growing interest in DOEs is mainly because of their flexibility in light manipulation with a small form factor and their ability to combine simultaneously optical and computational functions into a single part by applying the software-hardware co-design approach. Two main methods are widely used to fabricate DOEs. The first method is the etched-based method that combines photolithography and reactive-ion etching (RIE). The second method is additive fabrication, which combines metal deposition and nanoimprinting (NIL). Both methods have many drawbacks. The RIE methods suffer from issues like lags in the etched depth when the feature sizes differ in the same pattern (RIE lags), high surface roughness, and aspect ratio-dependent etching rate. The second method could produce high-resolution micro-optics. However, the technique could suffer from poor adhesion of the patterns with the substrate and poor uniformity across large areas. Here we propose a new way to fabricate multi-level DOEs by directly growing an optically transparent material on a glass substrate. The method combines the deposition of Silicon dioxide (SiO2) by Plasma-enhanced chemical vapor deposition technique (PECVD) and bi-layer lift-off. We provide evidence of the effectiveness of the fabrication method by comparing a 16-level Fresnel lens fabricated by the RIE method with another lens fabricated by the proposed method. The characterization results show that with the proposed method, the surface roughness is lower, and the depth is uniform. Furthermore, the optical test shows a reduced haze effect.

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Bilayer lift-off process for aluminum metallization

Cited by 13 publications

References 12 publications

Fabrication of a 3D high-resolution implant for neural stimulation - challenges and solutions

Fabrication of a 3D high-resolution implant for neural stimulation - challenges and solutions

A novel photoresist-based film-profile engineering scheme for fabricating double-gated, recess-channel IGZO thin-film transistors

Additive diffractive optical elements fabrication by PECVP deposition of SiO2 and lift-off process

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