RF-SAW filters on pyro-suppressed wafers

Vetelino, Kevin A.; Welsh, P. E.; Aguirre, Myriam H.; Abbott, Ben

doi:10.1109/ultsym.2004.1417759

Cited by 2 publications

(2 citation statements)

References 2 publications

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“…A large difference in the coefficient of the thermal expansion (CTE) between BST and LN or LT makes high-quality BST difficult to deposit at high temperatures (typically 600 ~ 700 °C). In addition, the pyroelectric effect can damage LN and LT when heated at such a high temperature [10].…”

Section: Introductionmentioning

confidence: 99%

Wafer–to–wafer transfer process of barium strontium titanate for frequency tuning applications using laser pre-irradiation

Samoto

Hirano

Somekawa

et al. 2015

J. Micromech. Microeng.

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This paper describes laser-assisted film transfer technology for barium strontium titanate (BST) deposited on a sapphire substrate. BST is a promising ferroelectric material for varactors, which are required for frequency-tunable RF applications. However, the deposition temperature of BST (600 ~ 700 °C) is too high for surface acoustic wave (SAW) substrates. In this study, BST grown on a sapphire substrate at 650 °C was transferred at low temperature (140 °C) to a borosilicate glass substrate as well as a LiTaO3 substrate. The transferred BST films were characterized as tunable capacitors. A key process in the BST film transfer technology is the laser pre-irradiation of a buffer Pt layer beneath BST from the backside of the sapphire substrate to weaken the BST-to-Pt adhesion. The mechanism of delamination at the BST/Pt interface is discussed using a simple 1D heat transfer model.

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Section: Introductionmentioning

confidence: 99%

Wafer–to–wafer transfer process of barium strontium titanate for frequency tuning applications using laser pre-irradiation

Samoto

Hirano

Somekawa

et al. 2015

J. Micromech. Microeng.

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show abstract

“…In addition, LT and LN can be damaged, when they are heated at such a high temperature. This is partly because the crystal surface accumulates electric charges causing spontaneous electrical discharge, when pyroelectric LT and LN are heated [12]. Another reason is a change in the chemical composition, which is more severe for LT than LN.…”

Section: Introductionmentioning

confidence: 99%

Integration of BST varactors with surface acoustic wave device by film transfer technology for tunable RF filters

Hirano

Kimura

Koutsaroff

et al. 2012

J. Micromech. Microeng.

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This paper presents a film transfer process to integrate barium strontium titanate (BST) metal-insulator-metal (MIM) structures with surface acoustic wave (SAW) devices on a lithium niobate (LN) substrate. A high-quality BST film grown on a Si substrate above 650 • C was patterned into the MIM structures, and transferred to a LN substrate below 130 • C by Ar-plasma-activated Au-Au bonding and the Si lost wafer process. Simple test SAW devices with the transferred BST variable capacitors (VCs) were fabricated and characterized. The resonance frequency of a one-port SAW resonator with the VC connected in series changed from 999 to 1018 MHz, when a dc bias voltage of 3 V was applied to the VC. Although the observed frequency tuning range was smaller than expected due to the degradation of BST in the process, the experimental result demonstrated that a tunable SAW filter with the transferred BST VCs was feasible.

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RF-SAW filters on pyro-suppressed wafers

Cited by 2 publications

References 2 publications

Wafer–to–wafer transfer process of barium strontium titanate for frequency tuning applications using laser pre-irradiation

Wafer–to–wafer transfer process of barium strontium titanate for frequency tuning applications using laser pre-irradiation

Integration of BST varactors with surface acoustic wave device by film transfer technology for tunable RF filters

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