ELSEVIER Thin Solid Films 313-324 I 1999) I OS- I 10 Electrical and structural properties of rapid thermal annealed RF sputtered silicon oxide films W.K. Choi”.“, K.K. Han”. W.K. Chimb Abstract The effect3 of oxygen mixing and rapid thermal annealing (RTA) on the electrical properties of RF sputtered silicon oxide films has been examined. It was found that the insulating property of the sputtered oxide films improved when prepared with oxygen mixing in the sputtering gas and/or after rapid thermal annealin g. For films RTA for 50 and 100 s. Schottky emission and space charge limited conduction were suggested as the transport mechanisms. The infrared results show that the tilm sroichiometry improved with RTA and/or oxygen mixing. ‘0 1999 Elsevier Science %A. All rights reserved. Kry:ordJ: Annealing; Melnl-aside-semiconductor strucrure: Silicon oxide: Spurtering 1. Introduction Recently. we reported the results of electrical and struc- tural measurements on RF sputtered silicon oxide films prepared under difierent sputtering pressures [ 1.91. The insulating properties of the films were found to improve when sputtered at lower pressures or on rapid thermal annealing (RTA) at elevated temperatures.We also found that the RTA films are denser than the as-prepared films. In this paper. we presentthe resultsof electrical measurements and infrared spectroscopyon films prepared under different concentrations of oxygen mixing in the sputtering gas (QO:) and RTA conditions. 2. Experimental N-type silicon wafers of 5-10 0 cm resistivity and (100) in orientation were used as substrates.The wafers were cleaned with RCA solutions and a 10% hydrofluoric acid. After cleaning. the wafers were rinsed in de-ionized water and dried in a nitrogen ambient. The sputtering was carried out using an Anelva SPH-210H machine with a 4 inch. 99.99% pure silicon dioxide target. Rapid thermal annealing was carried out on an A.S.T. model SHS 10 system with argon ambient at a temperature. T?.for a period of time. t,. Details of the sputtering and RTA processes can be found in x Correspondin@ author. Tel.: f 65574G73: fax: - 65ii91103. E-tnnil oddrrrs: elechoi@nnus.cdu.sg 0V.K. Choi) our previous papers [1,3]. The sputtering conditions are shown in Table 1. Three main types of samples (i.e. the PO.P5 and PI0 series) were depositedwith the %OZ fixed at 0. 5 and 10%. The current versus voltage (l-r’) measurements were performed on metal-oxide-silicon CMOS) capacitors with aluminum contacts using a HP4155.A semiconductor para- meter analyzer. During the measurements. the device was placed in an enclosed probestation with nitrogen constantly flowing over the device surface. Note that in this work. forward bias refers to positive bias being applied to the top contact. The infrared experiments were carried out using a Fourier transform infrared spectrometer (model Magna-IR 850). 3. Results and discussions Fig. 1 shows the forward I-1’ characteristics of films preparedwith different c/CO?. Samples PO and PlO are the most leaky and the most insulating as-prepared films. respectively. The breakdown field (E,,) of the oside films ar I = 0.1 p-A increases from 0.1 MV/cm (PO)to 0.6 MV/cm (PlO) as the %O? increases from O-IO%. The PO series of films generally becomes more insulating asa result of RTA. Annealing at 700°C only slightly reducesthe film conduc- tivity ((T) (at I V) from 6.J x IO-“’ (PO’) to 1.9 x IO-“’ 0-l cm-’ . Annealing at 900 and 1000°Creduce (T significantly to 2.54 X IO-:’ and 9.5 X lo-” 0-l cm-‘. respectively. OCMO-6090199/$ - see from matter c 1999 Elsevier Science S.A. All rights reserved. PII: SOO-IO-6090t98)O 1613-X