We have developed a single wafer rapid thermal processing ͑RTP͒ module for low-pressure chemical vapor deposition ͑LPCVD͒ of silicon nitride. Nitride films were grown from dichlorosilane ͑DCS͒ and ammonia at 740°C under a pressure of 0.5 Torr. The DCS:NH 3 gas flows of 25:75 sccm provided Si 3 N 4 films 40 Å thick in 1 min. Successive 25 wafer runs resulted in consistent average thickness and uniformity ͑below 1.0% 1͒. The within wafer thickness range ͑max-min͒ was less than 2 Å. Conformal coverage over nonplanar substrates was also demonstrated. The hot-wall reactor configuration suppresses the condensation of NH 4 Cl byproduct.Rapid thermal processing ͑RTP͒ is an emerging technology in integrated circuit ͑IC͒ fabrication, and a potential substitute for conventional batch furnace processing. RTP has shorter process time and better temperature control, which could achieve higher throughput and better film uniformity than the batch process as future wafer production moves to 300 mm diam size. The known applications of RTP include thin gate oxide formation, ion implantation anneal, polysilicon chemical vapor deposition ͑CVD͒, and titanium or cobalt silicide formation. 1 We recently developed a prototype for a hot wall single wafer RTP module for thin gate oxide applications. 2 High quality gate oxides ranging from 20 to 50 Å thick were grown in this system using both wet and dry oxidation ambients. The unique quartz reactor configuration allows the use of HCl gas in the system to improve the gate oxide properties. In addition, anneal capability of oxide films in nitric oxide ͑NO͒ and nitrous oxide (N 2 O) was demonstrated.This paper extends the application of our single wafer RTP system to low-pressure chemical vapor deposition ͑LPCVD͒ of silicon nitride from dichlorosilane ͑DCS͒ and ammonia. Silicon nitride has been utilized in IC processing as an oxidation mask, a diffusion barrier to metal contamination, oxide-nitride-oxide gate stacks, 3 and DRAM capacitors. 4 Capacitor applications often require nonplanar device configuration, where conformality of capacitor layers is important. Silicon nitride films are commonly fabricated in batch furnace process from DCS or silane (SiH 4 ) with ammonia. 1 While the conformality of the DCS-based nitride films is superior to that of films formed using SiH 4 and NH 3 , 5 the major obstacle to using DCS and NH 3 in a cold wall rapid-thermal CVD ͑RTCVD͒ processing is condensation of ammonium chloride, NH 4 Cl, as a solid byproduct according to 6 3SiH 2 Cl 2 ϩ 10NH 3 → Si 3 N 4 ϩ 6NH 4 Cl ϩ 6H 2 In this study, thin nitride films 40 Å thick were successfully grown by LPCVD with excellent uniformity and repeatability on 200 mm diam silicon wafers from DCS and ammonia using a new single wafer RTP module. Conformal step coverage of the nitride films on nonplanar substrates was also achieved. The hot wall reactor configuration suppresses the condensation of ammonium chloride. The solid NH 4 Cl formed during the deposition can be collected in an air-cooled trap downstream of the hot-wa...
We have developed single-wafer furnace rapid thermal process ͑RTP͒ modules for thermal oxidation of silicon substrates. Dry oxides 20 Å and wet oxides 25 Å thick were grown on both 200 and 300 mm diam Si wafers with excellent thickness uniformity and repeatability. Thermal oxynitridation in nitric oxide ͑NO͒ and reoxidation can provide sub-25 Å oxides. The thermal stress within the silicon wafer was maintained at low levels. It is demonstrated that high quality thin gate oxide films, comparable to those grown in a conventional furnace, can be generated without the drawbacks associated with lamp-based RTP systems.Improving gate dielectric properties is a key requirement for enabling future high performance integrated circuits. For the next several device generations, silicon dioxide will still be an integral part of advanced gate dielectrics. To simplify and improve many aspects of rapid thermal processing ͑RTP͒ technology, we developed a single-wafer hot wall RTP system designed for thin oxidation applications as well as low-pressure chemical vapor deposition ͑LPCVD͒. 1,2 RTP offers a shorter process cycle time and better within-wafer film uniformity than the batch process. It is an attractive technology as future wafer production moves to 300 mm diam size for cost reduction.Most single-wafer oxidation tools have been conventionally lamp-heated systems. Some of these systems have difficulty growing high quality oxides in steam or chlorine-containing gases as a result of using stainless steel as a material of construction. Lampbased tools also suffer from inconsistent temperature measurement and control due to variations in the wafer emissivity.This paper focuses on thermal oxidation of both 200 and 300 mm diam silicon substrates using a single-wafer RTP tool that utilizes a hot-wall isothermal chamber. It maintains the advantages of batch furnaces, but does not suffer from reduced throughput for small batch sizes nor sensitivity to wafer emissivity variations. Results on the wafer show excellent process repeatability and uniformity, and slip-free wafers in processes up to 1050°C. The newly developed hot-wall RTP system is capable of producing both wet and dry oxides. Uniform oxide films of sub-25 Å can be grown consistently with or without NO nitridation. ExperimentalThe reactor configuration is shown schematically in Fig. 1. The process chamber consists of a quartz chamber surrounded by a heating assembly. The multizone heaters, along with a silicon carbide or SiC-coated graphite thermal diffusion plate, allow the system to achieve excellent thermal uniformity in the upper portion of the process tube. The wafer is heated by elevating it from a lower cooling chamber to an upper hot chamber. A shutter system thermally isolates the cooling and hot chambers. The wafer rotation aids thermal uniformity as well as uniform gas distribution across the wafer.All films were grown on 200 or 300 mm diam p-type Si͑100͒ wafers. Thermal oxidation and oxynitridation in nitric oxide ͑NO͒ were performed using the process sequence ...
We have developed single-wafer RTP modules for LPCVD of silicon nitride, oxynitride, oxide, and oxide/nitride/oxide (ONO) composite films. All films were deposited from dichlorosilane (DCS) as a silicon source gas.The deposition of 20-408, silicon nitride films from DCS and NH3 showed excellent thickness uniformity. Continuous 10-wafer runs at 735OC resulted in 40 8, Si3N4 films with within-wafer uniformity below 0.55% (lo) and wafer-towafer uniformity of 0.50% (lo). Conformal coverage of nitride over non-planar substrates was also demonstrated. The hot-wall reactor configuration suppresses the condensation of "&1 solid byproduct. An activation energy of 1.49eV was derived from the depositions at a reactor pressure of 0.5 Torr and DCS:NH3 =1:3.Oxynitride films were deposited from DCS/NH3/N20 at 800OC. A film composition of SiOo.6Nl.l with a refractive index of 1.80 was obtained.Silicon dioxide (high temperature oxide, HTO) films can also be grown at 8OOOC from DCS and N20.ONO stack films of 170A were deposited in-situ at 800°C using sequential depositions of HTO/nitride/HTO. An Auger electron spectroscopy depth profile of the film revealed a sandwich structure of the film composition.
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