Data processing: measuring – calibrating – or testing – Measurement system in a specific environment – Electrical signal parameter measurement system
Reexamination Certificate
2001-03-22
2003-04-01
Hoff, Marc S. (Department: 2857)
Data processing: measuring, calibrating, or testing
Measurement system in a specific environment
Electrical signal parameter measurement system
C702S104000
Reexamination Certificate
active
06542835
ABSTRACT:
BACKGROUND
This invention relates to improved methods and apparatus for collecting information, more particularly, electronically collecting data from multiple locations such as, for example, data collection from an array of sensors.
The successful and cost effective manufacture of many common components (e.g. integrated electronic circuits) requires that processing conditions or properties be maintained at optimal values over relatively large areas or volumes. The ability to obtain process condition data from many, discrete locations within a processing system (i.e. spatially resolved data) is very valuable in establishing and maintaining optimal component yields and performance. Further, many common processing operations require that process variables change in a consistent, reproducible way as a function of time (i.e. process trajectory) rather than have a single, time independent value. The ability to obtain process condition data at many, discrete points in time (i.e. temporally resolved data) is also very valuable in establishing and maintaining optimal component yields and performance.
Most sensors and sensing methods either obtain data at discrete physical locations (e.g. thermocouples measuring temperature) or measure an average (or integrated) value for the entire process area or volume (e.g. optical emission from a plasma discharge). These limitations are usually an inherent property of the sensor and/or measurement parameter. There are a number of standard methods and approaches that have been developed in an attempt to obtain spatially and temporally resolved process data, each of which has its own set of strengths and weaknesses.
One of the standard methods uses swept sensors that include a sensing element wherein the sensing element is physically moved within the processing area while multiple measurements are being made. The individual measurements are then correlated with the sensor location to produce a spatially resolved mapping of the parameter of interest. The primary advantage of this method is that only a single sensor and measurement system is needed. The disadvantages are: the spatial data is strongly convoluted with any temporal variations (i.e. one cannot know if the signal changed as a function of time or location or both), and the often-undesirable difficulties of physically moving an object within the processing environment.
Another standard method involves deconvolution of integrated sensor data. Specifically, multiple measurements of an integrated value are made (e.g. line-of-sight optical emission) wherein the multiple measurements contain a different mix of the measurements (e.g. different viewpoint). The primary advantage of this approach is that only a small number of sensors and measurement systems are needed, possibly even only one. A primary disadvantage is that the deconvolution of the sensor data set to produce a spatially resolved map is subject to mathematical assumptions and requirements that are difficult to achieve in real world measurements. In addition, the mathematical techniques used to deconvolute the sensor data tend to be very noise sensitive such that small sensor errors can lead to large spatial errors.
One of the most straightforward of the standard spatial mapping approaches uses multiple, fixed sensors. In a typical arrangement, numerous, identical sensors are simply distributed throughout the area or volume of interest. The primary advantage is one of simplicity in both data acquisition and analysis; spatial and temporal effects are completely decoupled. The primary disadvantage is the large number of sensors and measurement systems required to obtain the desired spatial resolution. For some applications, the cost and complexity of installing and maintaining a large number of independent sensors and the respective data collection network are unacceptably high. This is particularly true for applications such as those where spatial and temporal sensor maps are desired for process tools such as those used for electronic device fabrication. Indeed, when this approach is used for characterizing process tools, it is usually limited to very coarse spatial resolution applications and only uses a relatively small number of sensors.
Clearly, there are numerous applications requiring reliable and efficient methods and apparatus for spatially resolved and time resolved data collection from one or more sensors. In addition, there is a need for methods and apparatus capable of acquiring highly spatially resolved measurements while avoiding or minimizing one or more disadvantages of the standard methods. Furthermore, there is a need for methods and apparatus capable of accommodating multiple sensor types and capable of measuring multiple parameters. Still further, there is a need for methods and apparatus that enable limited data acquisition and measurement resources to be more efficiently shared by a large number of sensors.
SUMMARY
This invention pertains to improve data acquisition such as for mapping one or more parameters spatially, temporally, or spatially and temporally. The present invention seeks to overcome one or more of the deficiencies of the standard technologies for data acquisition.
Practicing aspects of the present invention includes activating multiple crosspoint nodes by applying electrical signals to the crosspoint nodes simultaneously and making measurements for one or more activation states. Data from one or more nodes are then mathematically extracted from the set of measurement data.
One aspect of the present invention includes apparatus for acquiring data. In one embodiment, the apparatus includes output electrical conductors, input electrical conductors, and sensors. The sensors are capable of presenting a measured parameter as an electrical impedance. Each of the sensors is connected with one of the output electrical conductors and one of the input electrical conductors so as to form an array of crosspoint connections. Applying electrical signals to the output electrical conductors and measuring electrical signals at the input electrical conductors, generates sufficient information to derive the measured parameter of each sensor using algorithms that include equations for combining electrical impedances.
In a further embodiment, the apparatus includes a controller for applying the electrical signals and for measuring the electrical signals.
Another aspect of the present invention includes methods of acquiring data. In one embodiment, the method is used for obtaining data from an array of sensors in a crosspoint network. The sensors are capable of representing one or more measured parameters as electrical impedance. The method includes the step of applying a pattern of electrical signals to the sensors. The method also includes measuring electrical signals from the sensors. Still further, the method includes the step of deriving measurement data for each of the sensors using the measured electrical signals and algorithms that include equations for combining electrical impedances.
Another aspect of the present invention includes a computer-implemented algorithm for deconvoluting combined electrical impedances from an array of sensors. The algorithm is derived from equations that represent combined discrete impedances. The equations are manipulated to obtain a set of equations having the number of unknowns equal to or less than the number of equations. The algorithm further includes the mathematical steps for solving the equations using measured electrical data representing the combined impedances.
It is to be understood that the invention is not limited in its application to the details of construction and to the arrangements of the components set forth in the following description or illustrated in the drawings. The invention is capable of other embodiments and of being practiced and carried out in various ways. In addition, it is to be understood that the phraseology and terminology employed herein are for the purpose of description and should not be regarded as limiting.
As such, those skilled in the art
Hoff Marc S.
Miller Craig Steven
OnWafer Technologies, Inc.
Williams Larry
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