The conventional premise that metrology is a "non-value-added necessary evil" is a misleading and dangerous assertion,
which must be viewed as obsolete thinking. Many metrology applications are key enablers to traditionally labeled
"value-added" processing steps in lithography and etch, such that they can be considered integral parts of the processes.
Various key trends in modern, state-of-the-art processing such as optical proximity correction (OPC), design for
manufacturability (DFM), and advanced process control (APC) are based, at their hearts, on the assumption of fine-tuned
metrology, in terms of uncertainty and accuracy. These trends are vehicles where metrology thus has large opportunities
to create value through the engineering of tight and targetable process distributions. Such distributions make possible
predictability in speed-sorts and in other parameters, which results in high-end product. Additionally, significant reliance
has also been placed on defect metrology to predict, improve, and reduce yield variability. The necessary quality
metrology is strongly influenced by not only the choice of equipment, but also the quality application of these tools in a
production environment. The ultimate value added by metrology is a result of quality tools run by a quality metrology
team using quality practices.
This paper will explore the relationships among present and future trends and challenges in metrology, including
equipment, key applications, and metrology deployment in the manufacturing flow. Of key importance are metrology
personnel, with their expertise, practices, and metrics in achieving and maintaining the required level of metrology
performance, including where precision, matching, and accuracy fit into these considerations. The value of metrology
will be demonstrated to have shifted to "key enabler of large revenues," debunking the out-of-date premise that
metrology is "non-value-added." Examples used will be from critical dimension (CD) metrology, overlay, films, and
This paper summarizes the work completed to determine if and how an electron beam affects the performance, reliability, and yield of an advanced copper semiconductor device. This study was done in the Kilby Fab of Texas Instruments located in Dallas, Texas. As IC technologies advance to smaller and smaller dimensions, the techniques used to detect defects needs to advance as well. Also the unique nature of defects and the defect mechanisms for copper dual damascene processes are much different than what was seen in the past with Al technologies that further complicate defect detection. The days of using only visible light to inspect wafers for defects is coming to an end. For these advanced technology devices, killer defects can be smaller than 0.15mm in size and may be invisible optically. To detect these types of defects, new light sources must be used to be able resolve these. Scanning electron beam (SEM) inspection has been introduced recently as a new tool to detect these defects and to give further capability to detect defects that may only have an electrical signature. For the defects which exhibit electrical defect characteristics, the scanning electron beam inspection tool can be used to charge the device under the scan causing a voltage contrast and actually detect electrical abnormalities in the circuit that can be caused by a defect in some underlying area. There has been much concern in the semiconductor industry however; that the electron beam itself can damage or affect the transistor characteristics due to the high voltage, or landing energy that is commonly used in an electron beam system. The depth of penetration of the electron beam into the layer of the wafer is dependent on the energy of the electron beam striking the surface. Another concern is that through time, the chamber walls are deposited with various contaminants such as carbon due to outgassing and the interaction of the electron beam and certain materials on the surface of the wafer being inspected, this material can be left on the surface of the wafer where the electron beam scanned. This residue can then affect the processing subsequent to the electron beam inspection causing adhesion issues or improper deposition. This paper will detail a study in which an advanced technology copper dual damascene logic device, along with a defect density test device, are subject to a scanning electron beam inspection at numerous points in the process and attempt to document the effects on the transistor performance and wafer processing. The results that were obtained from both sets of tests were that neither the transistor parametrics nor reliability were affected by the electron beam.
This paper summarizes the work completed as part of the Equipment Evaluation Program (EEP) for the Applied Materials SEMVision cX at Texas Instruments' KFAB facility. This tool employs real time Automatic Defect Classification (ADC) software in conjunction with an Automatic Defect Redetection (ADR) capability. The SEMVision cX utilizes a unique imaging system that employs multiple detectors to create several perspectives of the defect image. These perspectives enhance certain features of the defect that facilitate Automatic Defect Redetection of all defect types, and enable a rule- based ADC system. This tool was designed to meet the requirements of an advanced CMOS fab, which requires increased imaging resolution to resolve the ever-smaller defects that can cause yield loss. This evaluation program was begun to accomplish three objectives: (1) To evaluate the tool for automatic defect classification on advanced CMOS technology. (2) To increase speed/throughput/resolution of defect review. (3) To increase the accuracy of defect classification with the use of ADC. Of great importance for TI's advanced wafer fabs is the need for a defect review SEM that also has the capability of ADC to improve defect classification accuracy and also to improve queue time in the Yield Enhancement (YE) operations. In addition to this, the need to be fully integrated into the fab DMS (Defect Management System) and TI's Automation system is crucial for automating many routine functions for the YE group. With the YE group personnel freed from the many tedious data management tasks, they can work on yield issues in real-time. The SEMVision cX differs from usual fab SEM's in that it employs MPSITM (Multiple Perspective Imaging) which is three detectors, one at normal incidence to the wafer and two on either side of normal from the electron beam. This configuration of detectors gives added information to the ADC system, provides for robust redetection, and establishes a paradigm for automatic defect classification based on topography and material perspectives. The SEMVision cX met all of the requirements during the evaluation with the exception of the tilt and rotate capabilities. There were two areas that were involved in this evaluation, one was for the defect review SEM itself and the other was for Automatic Defect Classification (ADC). Also included in this evaluation was the integration of the SEMVision cX into TI's DMS (Defect Management System) and Automation networks.