David R. Lopes

Ultra-shallow junction technology for 100 nm CMOS: xR LEAP implanter and RTP-centura rapid thermal annealer

Abstract Implantation of boron at sub-keV energies, combined with rapid thermal annealing in the temperature range from 900 to 1050 °C with soak times of 20 s or less results in activated junctions with depths of the order of 50 nm. These depths are consistent with roadmap estimates of transistor requirements for 100 nm scale devices for 16 Gb DRAM technology.

Nitrogen Profile Engineering in Thin Gate Oxides

In order to prevent boron penetration in PMOS transistors without degrading channel mobility, it is necessary to engineer the distribution of nitrogen introduced into the gate oxide. We have investigated methods of engineering this distribution using nitric oxide (NO) gas in an RTP system to thermally nitride ultra-thin gate oxides. In one approach, the gate oxide is simultaneously grown and nitrided in a mixture of nitric oxide and oxygen. For a 40 A film, SIMS depth profiling shows that this process moves the nitrogen peak into the bulk of the oxide away from the oxide silicon interface. In another approach, an 11 A chemical oxide produced by a standard pre-furnace wet clean is nitrided in NO at 800 deg. C. This film is subsequently reoxidized in either oxygen or steam. For an 1100 deg. C., 120 sec RTP reoxidation in oxygen, the final film thickness is 41 A. The nitrogen has a peak concentration of 5 at. % and the peak is located in the oxide 25 Afrom the oxide/silicon interface. Ramped voltage breakdown testing was carried out on MOS capacitors built using reoxidized NO nitrided films. They have breakdown characteristics that are equivalent to conventional furnace grown oxides. These films show considerable promise as gate dielectrics for CMOS technologies at geometries of 0.25um and below.

Uniform Ultra-Thin Oxides Grown by Rapid Thermal Oxidation of Silicon in N 2 O Ambient

In this paper, we report the study of rapid thermal oxidation of silicon in N 2 O ambient using the Applied Materials RTP Centura rapid thermal processor, and N 2 O oxide thickness and compositional uniformities with respect to gas flow rate and wafer rotation speed as well as other process parameters. It was found that N 2 O oxide uniformity is strongly dependent on gas flow rate and wafer rotation speed in addition to process pressure. With optimized setting of the process parameters, excellent oxidation uniformities (one sigma 2 O ambient. Nitrogen concentrations of such uniform oxides grown at 1050°C atmospheric pressure N 2 O oxidation processes were 1.7% for a 40A oxide and 2.5% for a 60A oxide, respectively, as characterized by SIMS analysis.

Ultrathin NO/N 2 O Oxynitride Dielectric For Advanced Flash Memory Application: Single Wafer and Batch Technology

In this paper a systematic investigation of nitrided oxides obtained by Rapid Thermal Oxidation/Nitridation (RTO/RTN) in AMAT Centura System is reported. Two different aspects were considered: first the comparison between single wafers and batch technology, second the different possible oxide architecture achievable with RTO/RTN system (i.e. RTO + RTN, RTN + RTO, RTN + RTO + RTN). Both morphological and patterned wafers were processed. Physical and chemical characterizations were carried out by means of SIMS, XPS, ELYMAT, AFM and Etching Rate studies. Morphological results were then correlated to electrical data obtained on MOS capacitors. The film obtained performing a NO RTN nitridation of the native oxide followed by a ISSG (In Situ Steam Generation) oxidation exhibited very promising electrical properties that made it an appealing candidate as gate dielectric in CMOS and Flash memories applications.