29.2: Silicon Ink‐Based Poly Si CMOS TFT Fabricated on 300mm Stainless Steel Foil Substrates

Takashima, Mao; Chandra, Aditi; Li, Joey H.; Kamath, Arvind

doi:10.1002/sdtp.10391

Cited by 3 publications

(2 citation statements)

References 3 publications

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“…First, a stainless-steel foil substrate compatible with high temperature processing was adopted over silicon wafers. Second, slot die coating of silicon ink was adopted to form the active layer [2] and third, screen printing was adopted for doping. Conventional metal sputtering and lithography were continued from there instead of inkjet for final highresolution processes.…”

Section: Introductionmentioning

confidence: 99%

Formulation and characterization of screen printable dopant ink for fabrication of polysilicon TFTs

Ito¹,

Kamath²

2021

Flex. Print. Electron.

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To move the promise of printed electronics from the laboratory to volume production required adopting a new approach eliminating ink-jet printing and adopting instead a hybrid mature print and conventional process. Novel screen printable N+ and P+ dopant inks were developed to fabricate polysilicon thin film transistors (TFTs). Semiconductor-grade dopant inks were formulated from a combination of thermoset plastic with boron and phosphor compounds. Inks were screen printed on polysilicon active islands on a 300 mm square stainless-steel foil substrate. The drain and source of the top gate TFTs were then formed via a thermal anneal activation. The residue after annealing was removed with an inoffensive process to avoid damage to the thin silicon layer and gate oxide. Doping was uniform across 300 mm sheet substrate. The sheet resistance was modulated to 200 Ω sq−1 for the N+ and 1000 Ω sq−1 for the P+ active layer. Field mobility of polysilicon TFTs fabricated using this screen-printed dopant process were 80 cm2V s−1 for PMOS and 200 cm2V s−1 for NMOS using low-cost, mature equipment, and an easily manageable process that is both scalable and compatible with roll-to-roll manufacturing.

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Section: Introductionmentioning

confidence: 99%

Formulation and characterization of screen printable dopant ink for fabrication of polysilicon TFTs

Ito¹,

Kamath²

2021

Flex. Print. Electron.

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“…We have previously shown that high performance polysilicon CMOS TFT devices on flexible stainless-steel substrates can be used to make low cost Near-Field Communication (NFC) tags at pilot scale production [4]. This results in a high throughput, low maintenance, and low step count process, capable of migrating to a R2R manufacturing line.…”

Section: Introductionmentioning

confidence: 99%

82‐2: Invited Paper: Roll‐to‐Roll Processing of Polysilicon TFTs on Flexible Large Area Stainless Steel Substrates

Chandra¹,

Kamath²,

Bruner³

et al. 2019

Symp Digest of Tech Papers

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Considerations and Methodology to Determine R2R Manufacturing and Scaling of Electronic Devices on Flexible Stainless Steel Foil Substrates

Chandra¹,

Takashima²,

Li³

et al. 2017

MRS Advances

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Stainless steel substrates enable a combination of low cost, flexibility, durability, high processing temperatures, and sub-100 um thickness making it well suited for sheet based and roll-to-roll processing. NFC (13.56 MHz) based circuits using high performance polysilicon TFTs on steel sheets have been manufactured using a hybrid printed process in a production environment. The process scheme utilizes a hybrid, additive materials approach encompassing low cost manufacturing steps such as slot die coating and screen printing of silicon and dopant inks to enable a high throughput, low cost, manufacturing flow. This paper describes the approach for migrating from a sheet-based hybrid process flow to a R2R-based process. A comparison of substrate choices and considerations for R2R process integration is presented. A sensitive electrical method for evaluating the feasibility of R2R-based process integration schemes and materials selection is presented. MIM capacitor leakage, TFT device characteristics, NFC circuit performance, and defect density considerations are shown as a function of steel substrate bending, down to a diameter of 0.75 inches. Electrical characteristics and optical inspections show no measurable change to insulator characteristics, demonstrating a high degree of flexibility and overall device and process capability for R2R processing.

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29.2: Silicon Ink‐Based Poly Si CMOS TFT Fabricated on 300mm Stainless Steel Foil Substrates

Cited by 3 publications

References 3 publications

Formulation and characterization of screen printable dopant ink for fabrication of polysilicon TFTs

Formulation and characterization of screen printable dopant ink for fabrication of polysilicon TFTs

82‐2: Invited Paper: Roll‐to‐Roll Processing of Polysilicon TFTs on Flexible Large Area Stainless Steel Substrates

Considerations and Methodology to Determine R2R Manufacturing and Scaling of Electronic Devices on Flexible Stainless Steel Foil Substrates

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