Bruno Ghyselen

Germanium-On-Insulator (GeOI) structure realized by the Smart Cut™ technology

First results on formation of thin film GeOI structures by the Smart Cut™ technology are presented in this paper. Thin single crystal layers of Ge have been successfully transferred, via oxide bonding layer, onto standard Si substrates with diameters ranging from 100 to 200 mm. Compared to SOI manufacturing, the development of GeOI requires adaptation to the available germanium material, since the starting material can be either bulk Ge or an epitaxial layer. Some results will be presented for GeOI formation according to the different technological options. Germanium splitting kinetics will be discussed and compared to already published results. To show good quality of the GeOI structures, detailed characterization has been done by TEM cross sections for defect densities, interfaces abruptness and layers homogeneities evaluation. AFM was used for surface roughness measurements. These results help define procedures that are required to achieve large diameter high quality GeOI structures.

Co-integrated dual strained channels on fully depleted sSDOI CMOSFETs with HfO/sub 2//TiN gate stack down to 15nm gate length

We report an original dual channel fully depleted CMOSFET architecture on insulator (DCOI) co-integrating strained-Si (nMOS) and strained-Si/sub 0.6/Ge/sub 0.4/ (pMOS) with HfO/sub 2//TiN gate stacks down to 15nm gate length. We demonstrate for the first time an I/sub ON/ improvement for short channel SOI of 10% at 35nm gate length (25% at 75nm, 100% on long channels) for both n- and p-MOSFETs and a more than 3 decades gate leakage reduction compared to a SiO/sub 2/ dielectric. Meanwhile, thanks to the dual channel engineering, a threshold voltage adjustment is performed with a mid gap single metal gate suitable for high performance (HP) CMOS.

Large Qxf product for HBAR using Smart Cut ™ transfer of LiNbO 3 thin layers onto LiNbO 3 substrate

In this paper, we propose a novel approach for HBAR devices using the Smart Cuttrade technology to obtain thin homogeneous X-cut single crystal films of LiNbO3. Sub-micron layers were successfully transferred onto LiNbO3 handle wafers. RF characterizations were performed around 1.95 GHz and quality factors in excess of 40 000 are extracted, proving the applicability of layer transfer by Smart Cut trade to acoustic devices. An excellent matching between simulations and experimental data as well as TCF measurements are presented in this paper.

High piezoelectric properties in LiNbO 3 transferred layer by the Smart Cut™ technology for ultra wide band BAW filter applications

For the first time, high overtone bulk acoustic resonators (HBAR) based on thin homogeneous and single crystalline films (below 1mum) of lithium niobate (LiNbO3) have been processed and characterized between 1 and 4 GHz. kt 2 greater than 30% are extracted from the frequency response envelope, by far superior to kt 2 usually obtained with traditional deposited AlN material (limited to 7%). This result confirms the interest of this technology for ultra wide band BAW (bulk acoustic wave) filters. The thin single crystalline LiNbO3 films together with an embedded metal electrode were fabricated using the Smart Cuttrade technology. The crystalline quality of the transferred layer (characterized by XRD and HRTEM) was found to be comparable to the single crystal bulk starting material.

Challenges and Progress in Germanium-on-Insulator Materials and Device Development towards ULSI Integration

SOITEC, Parc Technologique des Fontaines, F38190, Bernin, France The recent progress in the fabrication of GeOI substrates and devices is reviewed. Improvements have been made in threading dislocation density, Ge-buried oxide interface passivation, device performance. The potential of various co-integration schemes (lateral and vertical) has been illustrated as alternatives to the fabrication of n-type germanium channel devices. GeOI is also shown to be a versatile platform for the monolithic integration of Si and III-V devices and tunneling field effect transistors.

Germanium on double-SOI photodetectors for 1550 nm operation

In this paper, we have fabricated a resonant cavity enhanced (RCE) Ge-on-double-silicon on insulator (SOI) photodetector for operation around the 1550 nm communication wavelength. The enhanced response of this detector is attributed to both the resonant cavity effect as well as the strain induced band gap narrowing of the Ge layer.

Crystallographic orientation engineering in silicon-on-insulator substrates

A bilayer silicon-on-insulator film was engineered to locally convert the crystallographic orientation from (100) to (110). The initial bilayer film is composed of a first 50 nm thick (110) oriented Si surface layer, above a second 20 nm thick (100) oriented Si underlayer. The bilayer film was elaborated using hydrophobic bonding to ensure an atomic contact between the two layers without any intermediate oxide. A local and deep-amorphization was developed by ion implantation to amorphize the (100) oriented Si underlayer, conserving also a partially crystalline (110) oriented surface layer. After such a deep amorphization, a solid phase epitaxy regrowth was performed at 900 °C. Transmission electron microscopy observations confirm that the partially crystalline surface layer acts as a seed for the epitaxial regrowth of the amorphized areas through the hydrophobic bonding interface. Thus, the orientation is locally converted from (100) to (110) in the underlayer, which could lead to the elaboration of hybri...

Mode conversion in high overtone bulk acoustic wave resonators

High overtone Bulk Acoustic Resonators (HBAR) have been realized using the Smart Cut™ technology to transfer a thin X-cut LiNbO3 layer onto an X-cut LiNbO3 substrate. When the bonding of the two wafers is performed, an additional rotation along the normal axis is set to generate mode conversion between the two acoustic shear waves electromechanically coupled in X-cut LiNbO3. This enables excitation of only one of the two acoustic shear waves.

Realization and characterization of thin single crystal Ge films on sapphire

We have successfully produced and characterized thin single crystal Ge films on sapphire substrates (GeOS). Such a GeOS template offers a cost-effective alternative to bulk germanium substrates for applications where only a thin (<2 ?m) Ge layer is needed for device operation. The GeOS templates have been realized using the Smart CutTM?technique. 100?mm diameter GeOS templates have been manufactured and characterized to compare the Ge thin film properties with bulk Ge. Surface defect inspection, SEM, AFM, defect etching, XRD and Raman spectroscopy were all performed. The results obtained for each characterization technique used have highlighted that the material properties of the transferred thin Ge film were very close to the ones of a bulk Ge reference. An epitaxial AlGaInP/GaInP/AlGaInP double heterostructure was grown atop the GeOS template to demonstrate the templates stability under the conditions encountered in typical device realization. The photoluminescent behavior of this epitaxial structure was nearly identical to that of a similar structure grown on a bulk Ge substrate. The GeOS templates therefore offer a viable alternative to bulk Ge substrates in the fabrication of devices whose operation is compatible with a thin film structure.

InP-based composite substrates for four junction concentrator solar cells

A photovoltaics conversion efficiency of 46% at 508 suns concentration was recently demonstrated with a four-junction solar cell consisting in a GaAs-based top tandem cell transferred onto an InP-based bottom tandem cell, by means of wafer bonding. We have successfully produced and characterized different InPOS (for InP-On-Substrate) composite substrates, that could advantageously replace fragile and expensive InP bulk wafers for the growth of the bottom tandem cell. The InPOS composite substrates include a thin top InP layer with thickness below 1µm, transferred onto a host substrate using the Smart Cut™ layer transfer technology. We developed InP-On-GaAs, InP-On-Ge and InP-On-Sapphire substrates with surface and crystal qualities similar to the InP bulk ones. A low electrical resistance of 1.4mΩ.cm² was measured along the InP transferred layer and the bonding interface. An epitaxial bottom tandem cell was grown on an InPOS substrate, and the corresponding PL behavior was found identical to that of cells...