Wolfgang Aderhold

Low-Resistance Titanium Contacts and Thermally Unstable Nickel Germanide Contacts on p-Type Germanium

Ti/p-Ge and NiGe/p-Ge contacts are compared on both planar and fin-based devices. Ti/p-Ge contacts show low contact resistance, while NiGe/p-Ge devices show short circuit problems due to thermally driven Ni diffusion. Considering the thermal budget in the standard backend of line processing for CMOS, Ti is more suitable for p-Ge devices. A low Ti/p-Ge contact resistivity of 1.1 × 10-8 Ω · cm2 is achieved by using a multi-pulse laser annealing technique for B activation.

Ultralow-resistivity CMOS contact scheme with pre-contact amorphization plus Ti (germano-)silicidation

Following the previous study on Si:P [1], we also achieve ultralow contact resistivities (ρ_c) of ~2×10^-9 Ω·cm² on Si_0.3Ge_0.7:B using the same Ti based pre-contact amorphization (PCAI) plus post-metal anneal (PMA) technique. Similar as on Si:P, low-energy PCAI provides the lowest ρ_c on SiGe:B. By increasing the B concentration, the PMA temperature required on SiGe:B also matches with that on Si:P. A simple Ti based CMOS contact flow is thus proposed. Several B doping and activation methods on SiGe:B are also compared in this work.

Use of Virtual Metrology for in-situ Visualization of Thermal Uniformity and Handoff Adjustment in RTP Critical Anneals

Applied materials rapid thermal processing (RTP) systems are unique in providing high resolution process data particularly wafer rotation angle and wafer rotation speed as a function of time. This work explores how this information can be used to predict on-wafer process results using an advanced analysis package known as WISR (wafer interdiction and scrap reduction). WISR is an advanced process control platform for the collection, storage, visualization, and analysis of process parameters from production tools. One of the main analysis features of WISR is the ability to create virtual sensors. Virtual sensors are calculated parameters derived from physical sensors that can provide real-time and statistical representation of process health. The focus of this paper is the ability of WISR to transform time series chamber parameters from the pyrometers and the magnetic levitation controller into thermal wafer images at any time during the recipe execution and provide wafer-to-wafer handoff correction. These abilities constitute a virtual sensor module in WISR known as Virtual metrology (VM). We describe the implementation of the VM-analysis and show how temperature maps and handoff corrections correlate with offline metrology in RTP critical anneals. This is an innovative new method to significantly reduce wafer processing errors, enhance yield, and minimize production cost.

Virtual Metrology in RTP with WISR

The Applied Materials RTP systems are unique in providing high resolution process data particularly lamp power and temperature as a function of radial position and time. This work explores how these data can be exploited to predict on-wafer process results using an SPC analysis package named WISR. WISR is an advanced process control platform for collection, storage, visualization, and analysis of data from process tools. The product is collecting data at rates up to 100Hz. It has the ability of notification and interdiction if data goes outside of specification. One of its main features is the ability to create virtual sensors. These are parameters that are derived from physical sensors and provide a statistical representation of the process health. The focus of this paper is the ability of WISR to transform the time series chamber data from the pyrometers into thermal wafer images at any time window during the recipe execution. We describe the data analysis that was deployed, and show how temperature maps generated correlate with metrology data from RTP processes. This is a disruptive new method to significantly save monitor wafer cost, enhance yield and prevent wafer processing errors.

Photon Influence on P and B Diffusion

We investigate photon effects for two thermal processes: implanted dopant activation and diffusion; and silicon oxidation. Because the Applied Materials Radiance Plus RTP system heats only one side of the wafer with lamps, the thermal and photon effects are separable by changing the side of the wafer that is irradiated. The difference in process results can then be interpreted in respect to the spectral difference of the lamp radiation and the grey body radiation emitted by the hot wafer. No significant effect due to the presence of high energy photons in either process was observed.

Sub-10 −9 Ω·cm 2 contact resistivity on p-SiGe achieved by Ga doping and nanosecond laser activation

We report record breaking values for PMOS source drain (S/D) contact resistivity, ρ<inf>c</inf> < 10⁻⁹Ω·cm². These were obtained by shallow Ga ion implantation on Si<inf>0.4</inf>Ge<inf>0.6</inf> in combination with subsequent pulsed nanosecond laser anneal (NLA). Cross section transmission electron microscopy (XTEM) shows the pc reduction mechanism is based on Ga and Ge segregation towards the surface.