INductively Couped pLasmas for CMOS-compatible etchINg of high performance III-V integrated laser sourcEs – INCLINE

The goal of this project is to develop a thorough understanding of the plasma kinetics and plasma-surface interactions in inductive discharges based on CMOS compatible chemistries (i.e. on gas chemistries deployed in the CMOS industry, as Cl2-HBr-O2 containing chemistries), that will form the fundamental basis for the subsequent demonstration of a CMOS-compatible etching process used in the fabrication of a high-performance integrated III-V laser source. With the steady recovery of the telecommunications market, and the development in the recent years of silicon photonics, manufacturing strategies compatible with large-scale fabrication, high throughput, high-reliability, and low-cost, will have important advantages. As a first example the world-wide development of fiber-to-the-home (FTTH) strategies will increase the need for transceivers including high-performance III-V emitters that could be fabricated at a large scale and a low cost, with more integration possibilities. Replacing laser facet cleaving or optical coating steps by on-wafer etching of facets or mirrors will become interesting in this context. In parallel, silicon photonics has demonstrated that most of the key-elements of an 'above-IC' optical interconnect layer can be fabricated with CMOS industrial processing techniques, and recent achievements both in USA and Europe have proven that the integration of a III-V micro-laser to the photonic layer should be feasible. Still, the processing of the III-V material directly in a CMOS line, being today considered as a promising approach, is still highly challenging. Highly integrated research programs have been launched at the national/ international level to deal with the global development of optical interconnects or photonic circuits onto CMOS or Si wafers. Many open questions still exist, one among them being the integration of the III-V etching steps in the CMOS fabrication line. Again, an anisotropic, highly reproducible III-V etching will be required. The fuller understanding and control of the etching parameters will become more important. The cost of fabrication and of operation should also not be increased. Reducing the number of processing tools required in the fabrication chain, and optimizing the use of fluids and consumables will participate in cost reduction, and will become the objective of components and equipment suppliers. The III-V optoelectronic industry has not been concerned with the problems of large-scale processing (ie > 100 mm) until now. On the other hand, R&D labs close to the CMOS-industry have developed a strong expertise in the monitoring of plasma etching processes and reaction chambers for silicon and related materials (crucial to maintain a high process yield on large surfaces), but have very few experience with III-V materials. The objective of the INCLINE project will be to concentrate the efforts of 4 academic research laboratories on this III-V etching issue, which we anticipate become a high topic in the industrial future of optoelectronics. Our three objectives will be i) to build the necessary fundamental expertise on plasma kinetics and plasma-surface interactions in inductively coupled plasma using CMOS-compatible chemistries, a domain where many open questions still exist; ii) to exploit this new expertise to propose a CMOS-compatible chemistry for the fabrication of an integrated laser micro-source with deeply etched mirrors, and to demonstrate for the first time the compatibility of this fabrication with a 200mm or300-mm etching tool; iii) to introduce monitoring techniques suitable for the control of the III-V etching process reliability. The INCLINE project will associate two research labs with well-recognized expertise in III-V laser processing belonging to the French ICT community, and two labs belonging to the plasma community with a well-recognized expertise in the field of plasma physics in inductively coupled discharges using reactive gas, including plasma kinetics and plasma-surface interactions. The project outcomes will be relevant for the fields of plasma science and technology, and optoelectronic engineering. In the field of plasma science and plasma engineering the project will first provide a 2D plasma model of CMOS compatible chemistry that will correctly depict real etching tools; second provide a 2D III-V etching model that will incorporate the passivation effects on the etched sidewalls. Both models will be constantly confronted to experimental characterizations of the plasma and the etched surfaces, many of these characterizations having never been carried out. In the field of optoelectronic engineering the final outcome of INCLINE project will be to demonstrate the successful CMOS-compatible fabrication of an edge emitting micro-laser with deeply etched mirrors of interest for optical interconnects, and an edge emitting laser with facet cleaving and optical coating steps replaced by an etching step.