Jaim Nulman

A steady-state throughput analysis of cluster tools: dual-blade versus single-blade robots

An analysis of throughput in a cluster tool with a dual-blade robot operating in steady-state mode is presented. The analysis is based on a single-wafer serial processing cluster tool. Two types of schedules are distinguished, called transport-bound schedules and process-bound schedules. In a transport-bound schedule changes in process times do not affect the throughput of the cluster tool, and denotes the maximum throughput achievable in the cluster tool. In a process-bound schedule, the process time predominates the effect on the throughput. The analysis indicates that a dual-blade robot improves the throughput of the cluster tool over a single-blade robot under process-bound conditions. Under process-bound conditions, a cluster tool with a single-blade robot would need to double the speed of the robot, compared with a dual-blade robot of equivalent speed, to achieve similar throughput. Under transport-bound conditions, the throughput of the cluster tool is the same for both dual-blade and single-blade cluster tools.

Correlation between aluminum alloy sputtering target metallurgical characteristics, arc initiation, and in-film defect intensity

Increasing levels of metallization, shrinking device geometries, and stringent defect density requirements have led to a continuous focus in the semiconductor manufacturing community to reduce defects generated during metal deposition by PVD techniques. Of particular interest in the metallization community is the reduction in in-film defect density in sputtered aluminum films. Pareto analysis of in-film defects in currently used interconnect metallization schemes suggest that a considerable portion of the in-film defects (up to 50%) are caused by unipolar arcing during aluminum deposition. Due to their unusual molten appearance, these defects are commonly referred to as splats. These defects can be as large as 500 micrometers , and due to their frequency of occurrence and size can significantly impact device yield in a manufacturing environment. Systematic investigations have revealed that the formation of splats, due to unipolar arcing, can be strongly correlated to the metallurgy of the aluminum alloy targets used during aluminum sputter deposition. The presence of undesirable metallurgical attributes such as alumina inclusions, porosity, oxygen content etc. are the primary causes for the occurrence of unipolar arcing. These undesirable metallurgical attributes appear to be the result of the manufacturing processes used to manufacture the aluminum alloy targets. The results of this study indicate that significant improvement in defect generation due to unipolar arcing during sputter deposition of aluminum films, and hence an improvement in device yield, is possible by reduction/elimination of the various undesirable metallurgical attributes in the aluminum alloy targets.

Sub-quarter micron metallization using ionized metal plasma (IMP) technology

Abstract Ionized metal plasma (IMP) technology has been developed for liners and wetting layer deposition of sub-quarter-micron devices. Numerical modeling showed the unique advantages of IMP source over ECR source and long throw sputtering in enhancing bottom coverage. TiN bottom coverage up to 70% were demonstrated. The deposition rate, uniformity, bottom coverage and film stress were optimized by tuning rf and dc powers, process pressure and bias power. The TiN film microstructure such as crystal orientation and grain size was controlled by process parameters. An IMP TiN x ( x x wetting layer. The via resistance was improved by IMP Ti deposition.

Emissivity Issues In Pyrometric Temperature Monitoring For RTP Systems

The emissivity of silicon wafers determine the temperature control in closed loop rapid thermal processing (RTP) systems. Silicon surface roughness, doping, and layers affect the intrinsic wafer emissivity, while RTP chamber walls reflectance reduces the amplitude of these effects. For temperatures below 600V, device side topography and layers also affect the emissivity of the wafer. Narrow band and wide band pyrometers show similar behavior with respect to layers on the wafer, as indicated by experimental and modeling techniques.

A Comparison of RTO and Furnace Oxides

The original intent of this study was to compare rapid thermal, thin (80-100A) gate oxides with standard, furnace-grown, thin gate oxides for endurance. Wafer processing before gate oxide growth was chosen to duplicate processing used ina typical non-volatile memory product. In particular, care was taken to duplipate pre- and post- gate growth processing of field oxide isolated polysilicon capacitors for all wafers in order to eliminate the previous difficulties in comparing oxides when different cleans and processing steps are used.[1] Substrate defects, atypical to this process, were presumably introduced during the initial wafer cleaning and scattered the time-to-breakdown (TTB) values during a constant current stress of these oxides to the point where statistical comparison of TTB averages was dubious. However, for unannealed wafers and for post polysilicon definition heat treatments of 900 ° C, RTO oxides grown with HCL had the same oxide trapping rate as the furnace oxides grown with TCA and RTO oxides grown in pure O 2 had a faster trapping rate. Higher temperature post polysilicon definition heat treatments had different effects. RTO oxides exhibited better yield than the furnace oxides. These results illustrate the differences between RTO and furnace oxidation in the presence of non-ideal wafer substrates.

Using cost of ownership (COO) modeling to optimize productivity and wafer output of sputtering tools

The SEMATECH COO model has been used as a design tool to optimize the hardware and application-dependent configurations of the Endura PVD system. The model helped identify and quantify the effects of improved equipment hardware, configurations, and processes. Sensitivity analyses were performed to determine the effect of throughput, chamber and system maintenance down time, reliability, equipment cost, consumables life and cost, and system configuration on cost per wafer (CPW) and wafer starts per week (WSPW). The results indicate that throughput and preventive maintenance down time have the greatest impact on COO. Equipment components were selected or designed and processes and procedures were developed to minimize the CPW and maximize the WSPW per tool. Increases in WSPW of 40 to 60% have been achieved by increasing overall throughput, decreasing PM time, and optimizing PM scheduling. These improvements can yield up to 25% reduction in cost per wafer.

Reactively sputtered coherent TiN process for sub-0.5-μm technology

TiN films were sputtered deposited through a collimating medium under different conditions where the sputter target was maintained in nitrided and non-nitrided modes. In-situ rapid thermal (RTP) annealing was done in an applied materials metal anneal chamber (MAC) integrated with the Endura physical vapor deposition (PVD) system. The barrier properties of these films were evaluated for tungsten plug application. Contact resistances and junction leakage data are presented. It is seen that the TiN films deposited in the non-nitrided mode possess excellent barrier properties. This method of deposition offers significantly improved wafer throughputs for coherent sputtering of TiN. The MAC offers an excellent alternative to the conventional furnace annealing approach for contact silicidation and provides a means for improving productivity.