Acoustic emission (AE) is used as a technique to monitor and characterize surface interactions between wafer and pad in a chemical-mechanical planarization (CMP) process for copper. A significant variation in in-situ AE signal was observed during controlled variation of the slurry composition, demonstrating the sensitivity of AE to the unique surface reactions taking place. Two different levels of AE were observed; a high root-mean-square (RMS) signal when polishing H2O2 treated copper, and a low RMS signal when polishing bare copper. The rate of change in the AE signal was also tied to variations in species concentration and pH in slurry.

The wireless token ring protocol (WTRP) is a novel medium access control (MAC) protocol for wireless local area networks (WLANs). In contrast with IEEE 802.11 networks, WTRP guarantees quality of service (QoS) in terms of bounded latency and reserved bandwidth, which are critical in many real-time applications. Compared to 802.11, WTRP improves efficiency by reducing the number of retransmissions due to collisions, and it is more fair as all stations use the channel for the same amount of time. Stations take turns transmitting and give up the right to transmit after a specified amount of time. WTRP is a distributed protocol that supports many topologies, as not all stations need to be connected to each other or to a central station. WTRP is robust against single node failures, and recovers gracefully from multiple simultaneous faults. WTRP is suitable for interaccess point coordination in ITS DSRC, safety-critical vehicle-to-vehicle communications, and home networking, and provides extensions to other networks and Mobile IP.

We present a hardware Gaussian noise generator based on the Box-Muller method that provides highly accurate noise samples. The noise generator can be used as a key component in a hardware-based simulation system, such as for exploring channel code behavior at very low bit error rates, as low as 10(-12) to 10(-13). The main novelties of this work are accurate analytical error analysis and bit-width optimization for the elementary functions involved in the Box-Muller method. Two 16-bit noise samples are generated every clock cycle and, due to the accurate error analysis, every sample is analytically guaranteed to be accurate to one unit in the last place. An implementation on a Xilinx Virtex-4 XC4VLX100-12 FPGA occupies 1,452 slices, three block RAMs, and 12 DSP slices, and is capable of generating 750 million samples per second at a clock speed of 375 MHz. The performance can be improved by exploiting concurrent execution: 37 parallel instances of the noise generator at 95 MHz on a Xilinx Virtex-II Pro XC2VP100-7 FPGA generate seven billion samples per second and can run over 200 times faster than the output produced by software running on an Intel Pentium-4 3 GHz PC. The noise generator is currently being used at the Jet Propulsion Laboratory, NASA to evaluate the performance of low-density parity-check codes for deep-space communications.

Chemical mechanical planarization (CMP) of Cu interconnects is a critical bottleneck technology for semiconductor manufacturing at the 65 nm technology node and beyond. The pad condition in CMP is of utmost importance in maintaining acceptable production quality and throughput, as it directly affects many different parameters in CMP including material removal rate (MRR) and process uniformity. Acoustic emission (AE) is a proven technique for in-situ monitoring of a wide range of manufacturing processes, and has been demonstrated for the in-situ monitoring of various phenomena in the CMP process such as endpoint and MRR detection. A novel graphical mapping approach of sensor signal for monitoring pad condition during Cu CMP is proposed and tested, with AE demonstrating improved sensitivity over that of friction force.