Hydrogen-Free Plasma-Enhanced Chemical Vapor Deposition of Silicon Dioxide Using Tetra-isocyanate-silane (Si(NCO) ₄)

Abstract

Small-dimension photonic devices for telecommunications applications have recently attracted increasing interest along with the development of dry etching techniques. Extremely accurate control of etching depth is often needed for the fabrication of these devices containing multiple quantum well (MQW) structures. The excellent anisotropy, reasonable etching rates and excellent compatibility with resist masks of reactive ion etching (RIE) permit this technique to be used for fabrication of such devices. A drawback of the technique is that it is difficult to control etched depth with an accuracy of the order of the QW dimension. Laser interferometry (reflectometry) (LIR) is a powerful method for in situ monitoring of MQW structure etching. End-point detection (EPD) with very high depth resolution is obtained by appropriately combining the operating parameters of RIE and of LIR acquisition.In this paper we discuss the use of LIR at 670 nm to monitor the etching of InP/InGaAs(P) MQW structures by CH 4 /H 2 /(Ar) RIE and we report the real-time monitoring for etching of a 0.5 nm thick InGaAsP layer embedded between InP layers which is, to the best of our knowledge, the highest resolution ever reported for this technique.In the MQW etching process, the use of LIR combined with RIE successfully detects all stack layers with a resolution better than the well/barrier thicknesses. This capability permits etching to be monitored with well thickness as small as 3 nm in the case of InP/InGaAs layers. For structures having well/barrier layers with similar composition and hence a small refractive index difference, such as two In 1−x Ga x As y P 1−y layers with y = 0.57 and y = 0.84 respectively, monitoring of the etching of MQW with well thicknesses as small as 5 nm is demonstrated.The technique illustrated in the paper also proved to be useful as a simple method of analysing structure layers: the sequence and the uniformity of the QWs can be characterized with very high resolution.

Focused electron beam induced deposition of pure SIO 2

“…The oxygen gas flux is controlled using a Brooks ® 5830 mass flow controller (full scale 10sccm), located outside of the chamber. Tetraisocyanatosilane (TICS, Si(NCO) 4 ) was chosen as precursor since it is a hydrogen free which is known to decompose in high quality OH free SiO 2 films in chemical vapor deposition and low temperature plasma enhanced chemical vapor deposition processes [13][14][15][16] . TICS is a white solid with a vapor pressure of approximately 1.3mbar at 22°C 17 .…”

Electroreduction of Si(NCO)4 for Electrodeposition of Si

“…Si(NCO) 4 as a precursor for vapor-phase deposition of Si-containing materials has been explored, as it is used in low temperature chemical vapor deposition of a-SiO 2 . 26,27 Though the pseudohalide functional group is similar to halogens in some homogeneous chemistry, it is unclear whether Si(NCO) 4 is electrochemically active and can be electroreduced to Si 0 .…”