Data processing: generic control systems or specific application – Specific application – apparatus or process – Product assembly or manufacturing
Reexamination Certificate
2000-01-04
2002-10-22
Picard, Leo (Department: 2125)
Data processing: generic control systems or specific application
Specific application, apparatus or process
Product assembly or manufacturing
C700S182000
Reexamination Certificate
active
06470230
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates generally to semiconductor fabrication technology, and, more particularly, to a method for semiconductor fabrication supervision and optimization.
2. Description of the Related Art
There is a constant drive within the semiconductor industry to increase the quality, eliability and throughput of integrated circuit devices, e.g., microprocessors, memory devices, and the like. This drive is fueled by consumer demands for higher quality computers and electronic devices that operate more reliably. These demands have resulted in a continual improvement in the manufacture of semiconductor devices, e.g., transistors, as well as in the manufacture of integrated circuit devices incorporating such transistors. Additionally, reducing defects in the manufacture of the components of a typical transistor also lowers the overall cost per transistor as well as the cost of integrated circuit devices incorporating such transistors.
The technologies underlying semiconductor processing tools have attracted increased attention over the last several years, resulting in substantial refinements. However, despite the advances made in this area, many of the processing tools that are currently commercially available suffer certain deficiencies. In particular, such tools often lack advanced process data monitoring capabilities, such as the ability to provide historical parametric data in a user-friendly format, as well as event logging, real-time graphical display of both current processing parameters and the processing parameters of the entire run, and remote, i.e., local site and worldwide, monitoring. These deficiencies can engender nonoptimal control of critical processing parameters, such as throughput accuracy, stability and repeatability, processing temperatures, mechanical tool parameters, and the like. This variability manifests itself as within-run disparities, run-to-run disparities and tool-to-tool disparities that can propagate into deviations in product quality and performance, whereas an ideal monitoring and diagnostics system for such tools would provide a means of monitoring this variability, as well as providing means for optimizing control of critical parameters.
Among the parameters it would be useful to monitor and control are critical dimensions (CDs) and doping levels for transistors (and other semiconductor devices), as well as overlay errors in photolithography. CDs are the smallest feature sizes that particular processing devices may be capable of producing. For example, the minimum widths w of polycrystalline (polysilicon or poly) gate lines for metal oxide semiconductor field effect transistors (MOSFETs or MOS transistors) may correspond to one CD for a semiconductor device having such transistors. Similarly, the junction depth d
j
(depth below the surface of a doped substrate to the bottom of a heavily doped source/drain region formed within the doped substrate) may be another CD for a semiconductor device such as an MOS transistor. Doping levels may depend on dosages of ions implanted into the semiconductor devices, the dosages typically being given in numbers of ions per square centimeter at ion implant energies typically given in keV.
However, traditional statistical process control (SPC) techniques are often inadequate to control precisely CDs and doping levels in semiconductor and microelectronic device manufacturing so as to optimize device performance and yield. Typically, SPC techniques set a target value, and a spread about the target value, for the CDs, doping levels, and/or overlay errors in photolithography. The SPC techniques then attempt to minimize the deviation from the target value without automatically adjusting and adapting the respective target values to optimize the semiconductor device performance, as measured by wafer electrical test (WET) measurement characteristics, for example, and/or to optimize the semiconductor device yield and throughput. Furthermore, blindly minimizing non-adaptive processing spreads about target values may not increase processing yield and throughput.
The present invention is directed to overcoming, or at least reducing the effects of, one or more of the problems set forth above.
SUMMARY OF THE INVENTION
In one aspect of the present invention, a method is provided for manufacturing, the method including processing a workpiece in a processing step, measuring a parameter characteristic of the processing performed on the workpiece in the processing step, and forming an output signal corresponding to the characteristic parameter measured. The method also includes setting a target value for the processing performed in the processing step based on the output signal.
In another aspect of the present invention, a computer-readable, program storage device is provided, encoded with instructions that, when executed by a computer, perform a method, the method including processing a workpiece in a processing step, measuring a parameter characteristic of the processing performed on the workpiece in the processing step, and forming an output signal corresponding to the characteristic parameter measured. The method also includes setting a target value for the processing performed in the processing step based on the output signal.
In yet another aspect of the present invention, a computer programmed to perform a method, the method including processing a workpiece in a processing step, measuring a parameter characteristic of the processing performed on the workpiece in the processing step, and forming an output signal corresponding to the characteristic parameter measured. The method also includes setting a target value for the processing performed in the processing step based on the output signal.
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Potts D C: “Manufacturing For Design: Putting Process Control In The Language Of The Designer” 1998 IEEE/SEMI, pp. 187-189, XP002164698, New York, NY.
Miller Michael L.
Sonderman Thomas
Toprac Anthony J.
Advanced Micro Devices , Inc.
Bahta Kidest
Picard Leo
Williams Morgan & Amerson P.C.
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