Data processing: measuring – calibrating – or testing – Measurement system in a specific environment – Electrical signal parameter measurement system
Reexamination Certificate
2001-03-19
2003-09-30
Hoff, Marc S. (Department: 2857)
Data processing: measuring, calibrating, or testing
Measurement system in a specific environment
Electrical signal parameter measurement system
C324S701000, C714S014000
Reexamination Certificate
active
06629045
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to the field of power supplies, and more particularly to detecting a malfunction of a slave power supply and triggering an interlock signal in response to the detection of the malfunction.
2. Description of the Relevant Art
As defined herein, a “power supply” is a device for the conversion of available power of one set of characteristics to another set of characteristics to meet specified requirements. In a typical application of a power supply, raw input power available in the form of 110V AC or 220V AC is converted to a controlled or stabilized voltage. A power supply system may include a number of power supplies coupled together. Examples of electrical parameters, properties or characteristics which are typically specified for a power supply may include output power, output voltage, output current, input voltage, input current, percent regulation, ripple effect, load impedance, resolution, and accuracy.
As defined herein a “signal” is a detectable and measurable physical quantity or impulse (such as a voltage, current, or power) by which messages or information can be transmitted from a source to a destination. For example, a signal representing a characteristic of a power supply, e.g., voltage, is measured in terms of a value and a measurement unit, e.g., 110 Volts AC. Power supplies play a vital role in the field of semiconductor manufacturing, where a power supply system is required to deliver voltages of up to 1500 volts for sputtering in thin film processing. Predictability, reliability, repeatability and cost are critical in an application such as this, where a malfunction in a power supply may result in the stoppage of a production line. The production loss and the subsequent rework may cost millions of dollars in lost profits. The following U.S. patents, which discuss various applications of power supplies, are hereby incorporated herein by reference: Apparatus for Removal of Electrical Shorts in a Sputtering System (U.S. Pat. No. 5,009,764), Method for Removal of Electrical Shorts in a Sputtering System (U.S. Pat. No. 4,963,238), Method and Apparatus for Recovery from Low Impedance Condition during Cathodic Arc Processes (U.S. Pat. No. 4,963,238), Topographically Precise Thin Film Coating System (U.S. Pat. No. 6,120,656), and Auto-ranging Power Supply (U.S. Pat. No. 6,011,704). The electrical power demand for sputtering in a aluminum chamber may require two power supplies. Referring to
FIG. 1
, a conventional arrangement of two power supplies as a master/slave power supply system
130
is illustrated. The power supply system
130
serves a manufacturing system
100
. One example of such a manufacturing system is the Endura® PVD (physical vapor deposition) system manufactured by Applied Materials, Inc., Santa Clara, Calif. One example of a power supply system is the MDX Series power supply, manufactured by Advanced Energy Industries, Inc., Fort Collins, Colo.
In
FIG. 1
, the load on the power supply system
130
is shared by a first power supply
110
and a second power supply
120
in a “master/slave” arrangement, that is, an arrangement in which the first power supply
110
controls the proportion of the load supplied by each one of the respective power supplies
110
and
120
. This arrangement may be configurable. For example, the master and the slave power supplies may be configured so that the master power supply
110
splits the load substantially equally with the slave supply
120
.
The master-slave power supply system
130
of
FIG. 1
is configured in a cascade arrangement, according to which the manufacturing system
100
sends a set point signal
140
to the master power supply
110
to represent an output power demand. This required power is variable since as the manufacturing process requirements change the need for power required by the manufacturing system may vary. For example, if the system
100
detects an impurity in the aluminum chamber the system will demand more power.
The master power supply
110
receives the set point
140
from the manufacturing system
100
and in response regulates its output and/or the set point
150
for the slave power supply
120
output. The slave power supply
120
receives the set point
150
and in response regulates its own output.
In response to the set point
140
received from the manufacturing system
100
, the master power supply
110
also sends to the manufacturing system
100
a signal
160
which is an estimate of the combined master-slave power supply output. In the system
130
of
FIG. 1
, the master power supply
110
always assumes that the slave power supply
120
is able to match the actual power output to the set point
140
received from the master. However, the slave power supply
120
might not be able to deliver the desired power output as specified by the set point
150
. This could be due to lack of capacity, for example, or due to some other malfunction. Since, as is illustrated in
FIG. 1
, there is, at least in some respects, an absence of feedback to the master power supply
110
from the slave
120
to indicate whether the slave power supply
120
has been able to adjust its output to match the set point
150
, a malfunction of a slave power supply
120
may not be known to the master. Thus, a need exists to detect a malfunction of a slave power supply
120
and trigger an interlock signal in response to the malfunction. Furthermore, this need is harder to address by a user of a power supply system
130
than it would be by the power supply developer. That is, when an existing power supply system must be retrofitted for detection of the slave power supply malfunction and triggering of an interlock there are more constraints than there would be if detection and interlocking were being designed for a power supply system during development of the system.
SUMMARY OF THE INVENTION
The problems outlined above are addressed by a system and method for detecting a malfunction of a slave power supply and triggering an interlock signal in response to the detection of the malfunction, as described herein.
Power supplies may be regulated in a variety of ways. In an embodiment of the present invention, a feedback technique is used, according to which a feedback signal provides information about voltage output to control circuitry of the power supply system. A set point signal establishes a target output level that the control circuitry attempts to maintain. The set point may be established through a manual setting or by a software program, for example. The control circuitry regulates the power supply by comparing the set point to the actual voltage output. A “malfunction” of the system occurs when the system fails to operate normally. If the control circuitry is not able to regulate the power supply output voltage, for example, this is abnormal and is thus a malfunction of the power supply.
In one embodiment, a master-slave power supply is configured in a cascade arrangement to supply power to a manufacturing system. A manufacturing system responds to the conditions of the manufacturing process by adjusting a set point for demanding a specified output power from the master-slave power supply. In response to receiving the set point from the manufacturing system the master power supply demands an output from the slave power supply such that the combined output power meets the specified output power.
In a first form, a method for activating an interlock signal upon detecting a malfunction of a slave power supply includes receiving a first input from the slave power supply representing the set point for the output power of the slave power supply, and a second input from the slave power supply representing the output power of the slave power supply. According to the method, a determination is made that the slave power supply system has malfunctioned if the received inputs substantially mismatch. In response to the determination of the malfunction, an interlock signal is activated.
In one aspect, the input received for
Chang Hong-Yi
Chao Chang-Hui
Chiang Wen-Huang
Hoff Marc S.
Kim Paul L
Taiwan Semiconductor Manufacturing Co. Ltd.
Tung & Associates
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