1. Field of the Invention
This invention relates generally to semiconductor manufacturing, and, more particularly, to a method and apparatus for performing field-to-field compensation for errors in semiconductor manufacturing processes.
2. Description of the Related Art
The technology explosion in the manufacturing industry has resulted in many new and innovative manufacturing processes. Today's manufacturing processes, particularly semiconductor manufacturing processes, call for a large number of important steps. These process steps are usually vital, and therefore, require a number of inputs that are generally fine tuned to maintain proper manufacturing control.
The manufacture of semiconductor devices requires a number of discrete process steps to create a packaged semiconductor device from raw semiconductor material. The various processes, from the initial growth of the semiconductor material, the slicing of the semiconductor crystal into individual wafers, the fabrication stages (etching, doping, ion implanting, or the like), to the packaging and final testing of the completed device, are so different from one another and specialized that the processes may be performed in different manufacturing locations that contain different control schemes.
Among the factors that affect semiconductor device manufacturing are effectively initiating and continuing a manufacturing process without significant human interaction, which can cause delays or errors in the manufacturing process. One of the process steps that is adversely affected by such factors is the photolithography overlay process. Overlay is one of several important steps in the photolithography area of semiconductor manufacturing. Overlay control involves measuring the misalignment between two successive patterned layers on the surface of a semiconductor device. Generally, alignment is important to ensure that the multiple layers of the semiconductor devices are connected and functional. As technology facilitates smaller critical dimensions for semiconductor devices, the need for reduced of misalignment errors increases dramatically.
Generally, photolithography engineers use results from the analysis of the overlay errors to make updates to exposure tool settings manually. Some of the problems associated with the current methods include the fact that the exposure tool settings are only updated a few times a month. Furthermore, often the exposure tool updates are performed manually. Similarly, improvements in error prevention and correction in other types of semiconductor manufacturing processes are also needed to improve yields in semiconductor manufacturing processes.
Generally, a set of processing steps is performed on a lot of wafers on a semiconductor manufacturing tool called an exposure tool or a stepper. The manufacturing tool communicates with a manufacturing framework or a network of processing modules. The manufacturing tool is generally connected to a machine interface. The machine interface is connected to a machine interface to which the stepper is connected, thereby facilitating communications between the stepper and the manufacturing framework. The machine interface can generally be part of an advanced process control (APC) system. The APC system initiates a control script, which can be a software program that automatically retrieves the data needed to execute a manufacturing process. The input parameters that control the manufacturing process are revised periodically in a manual fashion. As the need for higher precision manufacturing processes are required, improved methods are needed to revise input parameters that control manufacturing processes in a more automated and timely manner. Furthermore, wafer-to-wafer manufacturing variations can cause non-uniform quality of semiconductor devices.
Many times processed semiconductor wafers can have portions that contain errors, such as overlay errors. Often, a small error on a portion of a processed semiconductor can go unnoticed. This small error may cause a persistent bias in that portion, and subsequent processes may add to the error, causing a substantial error. Many times, these small errors can be caused by abnormalities in a stepper lens, errors in the manner the wafer is positioned in a stepper, and the like. Small residual errors, such as errors caused by persistent biases, can cause yield degradation in the manufacturing of semiconductor wafers.
The present invention is directed to overcoming, or at least reducing the effects of, one or more of the problems set forth above.