Evaluation of Low Temperature TEOS-Ozone Silicon Dioxide Thin Film CVD under Sub-Atmospheric Pressure Using Consecutively Pulsed Reactant Injection

Abstract

New approach for sub-atmospheric pressure silicon dioxide thin film deposition process at consecutively pulsed injection of tetraethylorthosilicate (TEOS) and ozone is presented. The study was performed with DCVD Centura D×Z tool. Deposition rates (DR) were as low as 0.03-0.1 nm/cycle and similar to those at atomic-layer deposition regime of thin film growth. The effects of deposition temperature, deposition process pressures and total reactant flows, ozone concentration, spacing, process cycle duration and total cycle numbers are presented. Deposition features were similar to those observed using continuous reactant delivery to the process chamber. DR values were found to depend strongly on ozone concentration and the surface of material used for CVD known as so-called "surface sensitivity" effect.Silicon dioxide thin film deposition on silicon using tetraethylorthosilicate (TEOS) was described for the first time in. 1 It was shown that TEOS is able to decompose in argon and hydrogen ambient at temperatures above 500 • C producing SiO 2 films with acceptable deposition rate (DR). However, TEOS was found to react with oxygen at temperatures as low as 300 • C with very low DR. Due to this, the only middle-temperature TEOS pyrolysis reactions 2 or low-temperature plasma-enhanced oxidation 3 processes are used in Integrated Circuit (IC) technology and production for a long time.Information about thermally-activated TEOS and ozone interaction at low temperatures appeared in the end of 1980 th . Silicon dioxide thin film deposition was performed either at atmospheric pressure chemical vapor deposition (APCVD) conditions, 4-9 or under subatmospheric pressure (SACVD) conditions. 10-14 Ozone with concentration more than about 1 weight % in oxygen was found to accelerate the film DR significantly. This made TEOS-ozone CVD process applicable for new generations of IC devices, basically due to urgent gap-filling needs of sub-quarter micron IC technology. A few lowtemperature thermally-activated IC production tools and CVD processes for thin films of silicon dioxide, phosphosilicate and borophosphosilicate glasses were studied and developed in a mid of 1990 th , 15-20 see also summary in the author's summary 21 and a monograph. 22 Unique features of TEOS-ozone CVD processes for silicon dioxide (frequently called also "undoped silicate glass", USG) were described in details in. 4-14 Among them the following three process features were most important. The first one was the effect of DR acceleration along with ozone concentration increase in between up to 1 weight %. A "surface sensitivity" effect at high ozone concentrations comes second. This effect is known as 10-30% differences in SiO 2 DR values and the film properties for the films grown on different surface types like silicon, silicon dioxide and silicon nitride. Finally, "flowlike" thin film deposition on stepped IC device structures was found. The latter feature allowed gap-filling of complicated IC device structures and solving some device planarization issues. To exp...

Review—Atomic Layer Deposition of Silicon Dioxide Thin Films

“…Thus, during the precursor stage, it was most likely that the -N(C 2 H 5 ) 2 ligands of the precursor reacted with the surface -OH (S*) groups producing the volatile product HN(C 2 H 5 ) 2 . Finally, the authors proposed similar surface chemical reactions [29] and [30] during the first ALD half of the cycle, as reported by Burton et al in Ref. 33 for the TDMAS precursor [18] (Table VI).…”

“…The dissociative chemisorption of DSBAS was estimated kinetically easily, with only a moderate activation barrier of 6.1 kcal mol −1 . This was recognized that this indicated that [29], followed by oxidation with ozone to form −Si(OH) 2 species (similar to the scheme [28]). The stage [29] for the removal of H 2 and the formation of −SiH 2 was found to be kinetically difficult with a calculated activation barrier of at least 36.8 kcal mol −1 , although oxidation with ozone was inherently easy.…”

“…Experimental studies 29 were performed using a commercial SACVD tool. The oxidation of the TEOS with an O 3 /O 2 mixture under conditions of subatmospheric pressure and a sequentially pulsed supply of reactants to the reactor were analyzed.…”

Review—Mechanical Stress in Chemically Vapor Phase Deposited Boron- and Phosphorus-Contained Silicate Glass Thin Films: A Review

“…It was characterized by the surface limited reaction scheme, taking into account the substrate surface properties 28 and specific TEOS-ozone CVD nucleation effects under different process conditions. 44,45 Ozone concentration plays the key role in this CVD reaction, providing high enough film deposition rates at low deposition temperatures.…”