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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Using a hot-wall rapid thermal system which permits single-wafer processing, thin gate dielectrics consisting of silicon nitride films were fabricated by low pressure chemical vapor deposition (LPCVD). Nitride layers deposited from dichlorosilane (DCS) and ammonia exhibited greatly reduced electrical leakage current compared to silane-based nitride films which are conventionally used in lamp-based single-wafer rapid thermal technology. After a postdeposition anneal, the DCS-based gate dielectric films showed better diffusion barrier properties against boron penetration than silane-based gate dielectrics at a dopant activation temperature of 1000°C.
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