Properties of a ‐ SiO x  :  H  Thin Films Deposited from Hydrogen Silsesquioxane Resins

Abstract

Ultralarge sale integrated circuit designs require multiple metal wiring layers for the formation of the device interconnections. Surface planarization and the deposition of high quality insulating films are critical fabrication steps related to the manufacture of these circuits. Planarization and dielectric deposition can be accomplished simultaneously using a spin-on process with hydrogen silsesquioxane (HSQ) resin to deposit amorphous SiO:H dielectric films. The use of this material in device manufacturing has increased as a result of the material's good planarization properties, eliminating the need for etchback procedures. More recently, it has been observed that HSQ-based films also provide the added benefit of relative permittivity less than SiO.,, which helps to minimize electrical delay. In order to obtain optimum properties from this material, tight process control and knowledge of the material's chemical behavior are necessary. Studies of the precursor material, film formation, and film properties have been performed. Also it is found that structural and compositional changes in the precursor during the film forming process play an important role in establishing the beneficial properties observed in HSQ-based dielectric films. InfroductionThe deposition of silicon dioxide thin films is a key step in the manufacture of semiconductor integrated circuits (ICs). Historically, ion beam sputtering and chemical vapor deposition have been used to deposit films in the 0.01 to 1.0 tim thickness range on dielectric, metal, and semiconductor surfaces. As circuit performance requirements have increased, the transistor density increased and the dimensions of the active device regions and circuit interconnections dropped well below 1.0 p.m. In these designs, multiple metal interconnection layers are essential. Today, IC designs with greater than three metal interconnection layers are common, and some microprocessors have as many as five levels. A common fabrication procedure for multilevel metal interconnection technology is the deposition of oxide films by spin coating silicon-based polymer solutions. The spin coating process planarizes the local wafer topography and facilitates the formation of void-free dielectric material between adjacent metal layers. Solutions of hydrogen silsesquioxane resin have emerged as a promising technology for the formation of planarizing oxide films. Oxide formation using this material has been shown to produce excellent local planarization and gap f ill1'2 and provides the added benefit of a dielectric constant lower than standard SiO,.Lower dielectric constant materials lower the capacitance between adjacent metal interconnections, in turn reducing electrical delay and paving the way to higher information processing rates.Hydrogen silsesquioxane (HSQ) resin is the polymeric analog of a family of spherosiloxanes previously explored by Five and Collins.5 These spherosiloxanes are highly ordered oligomers whose structure resembles a cage. The

Enhancement of moisture resistance of spin-on low-k HSQ films by hot wire generated atomic hydrogen treatment

“…This structural transformation results in significant lowering of the dielectric constant (k) down to 2.9. The associated vibrations of the network/cage structure in the HSQ films can be seen at 1070 (Si -O -Si network) and 1130 cm corresponds to the Si -H stretching mode [7].…”

Resists for sub-20-nm electron beam lithography with a focus on HSQ: state of the art

“…HSQ, were studied by Frye and Collins [63]. Later on, because of its properties (low dielectric constant, ranging between 2.6 and 3, excellent gap fill and planarization performance), HSQ started to be used as an interlayer dielectric material in high-performance integrated circuits [64][65][66]. The use of multiple metal interconnect layers became very trivial in the semiconductor industry, due to dimension shrinkage of the devices.…”

Low and Ultralow Dielectric Constant Films Prepared by Plasma‐enhanced Chemical Vapor Deposition

“…The organosilicon polymers were expected to preserve some characteristics of the silicon dioxide that would facilitate their integration in the interconnect structure. MSQ fi lms are deposited by spin-on techniques from precursor molecules that have nanoporous geometry and the polymerization processes preserves a part of the precursor's structure in the fi lms [39]. However, contrary to expectations, the integration of the spin-on fi lms with k < 3 proved to be diffi cult, mainly due to their poor mechanical properties and the tendency of the fi lms to crack.…”

“…The initial depositions were intended to prepare fi lms having a cage-type SiO structure similar to that of MSQ [39] and it was assumed that a ring-type cyclic siloxane precursor will be most suitable for that purpose [40]. It was expected that, by adjusting the plasma conditions for minimal dissociation of the molecules, the ring structure of the molecule could be preserved in the fi lm, inducing molecular nanoporosity, thereby creating a material with reduced density and corresponding lower dielectric constant.…”