US 5,303,139 AGranted

Low frequency, pulsed, bipolar power supply for a plasma chamber

AssigneeMagtron Magneto Elektronische Gerate GmbH

InventorGunter Mark

Life of this patent

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Abstract

The invention relates to a bi-polar power supply for a plasma chamber including an adjustable DC power supply having a positive output terminal and a negative output terminal. A transistor bridge circuit having two input bridge terminals is coupled to the positive and negative output terminals. Two bridge output terminals of the transistor bridge are coupled to the plasma chamber. A current detector is coupled to the two bridge output terminals for detecting the current flowing to the plasma chamber and controlling the transistor bridge circuit to provide a bi-polar power supply to the plasma chamber.

Claims8

Dependent claims

A bipolar power supply for a plasma chamber comprising:

an adjustable DC power supply having a positive output terminal and a negative output terminal;
a semiconductor bridge circuit having two bridge input terminals coupled to said positive and negative output terminals and two bridge output terminals coupled to the plasma chamber;
and
current detection means coupled to said two bridge output terminals for detecting the current flowing to the plasma chamber and controlling said semiconductor bridge circuit to provide a bipolar power supply to the plasma chamber;
wherein said current detection means comprises:
(a) a shunt having a tap coupled to said two bridge output terminals;
(b) two current detection and evaluation circuits coupled to said tap of said shunt and having a bipolar maximum current comparator;
(c) monitoring means coupled to said two current detection and evaluation circuits for monitoring the maximum current, the mean current, the temperature, an auxiliary voltage, and having a timer, a reset and an indication amplifier;
(d) a microprocessor coupled to said monitoring means;
and
(e) an interface, and two control signal processing units coupled to said microprocessor, said two control signal processing units each having a Schmitt trigger, a frequency limiter, a transmitter driver, and transmitter arrestor;
whereas said semiconductor bridge circuit includes four transistors each with a module driver, two of said transistors forming a first branch of said bridge circuit and having their module drivers coupled to one of said two control signal processing units, the other two of said transistors forming a second branch of said bridge circuit and having their module drivers coupled to the other of said two control signal processing units;
and
whereas said microprocessor receives signals from said two current detection and evaluation circuits and said monitoring means and through said interface instructs said two control signal processing units to switch said first and second branches of said semiconductor bridge circuit on and off to control and regulate the plasma intensity.

11 more elements

A bipolar power supply for a plasma chamber comprising:

an adjustable DC power supply having a positive output terminal and a negative output terminal;
a semiconductor bridge circuit having two bridge input terminals coupled to said positive and negative output terminals and two bridge output terminals coupled to the plasma chamber, said conductor bridge circuit including four transistors, two of said transistors forming a first branch of said bridge circuit and the other two of said transistors forming a second branch of said bridge circuit;
current detection means coupled to said two bridge output terminals for detecting the current flowing to the plasma chamber and controlling said semiconductor bridge circuit to provide a bipolar power supply to the plasma chamber, said current detection means comprising:
(a) an inductor and two free-wheeling diodes coupled to each branch for limiting the total current flowing through said branch;
(b) two independently adjustable current sensors, each coupled to one of said branches;
(c) two current detectors, each coupled to one of said current sensors;
(d) two control circuits, each coupled to one of said current detectors;
(e) an operational amplifier and a microprocessor coupled to said two control circuits;
(f) an interface and a process computer coupled to said operational amplifier and said microprocessor;
and
(g) four output driver controls, two of said four output driver controls coupled to one of said control circuits and coupled to two transistors of one branch, and the other two of said four output driver controls coupled to the other of said control circuits and coupled to the other two transistors of the other branch;
and
whereas said process computer receives signals from said two current sensors and said two current detectors and through said interface, said operational amplifier, said microprocessor and said two control circuits instructs said four output driver controls to switch said four transistors on and off to control and regulate the plasma intensity.

10 more elements

Dependencies are inferred from the claim text.

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Abstract

A bipolar power supply for a plasma chamber comprising:

an adjustable DC power supply having a positive output terminal and a negative output terminal;
a semiconductor bridge circuit having two bridge input terminals coupled to said positive and negative output terminals and two bridge output terminals coupled to the plasma chamber;
and
current detection means coupled to said two bridge output terminals for detecting the current flowing to the plasma chamber and controlling said semiconductor bridge circuit to provide a bipolar power supply to the plasma chamber;
wherein said current detection means comprises:
(a) a shunt having a tap coupled to said two bridge output terminals;
(b) two current detection and evaluation circuits coupled to said tap of said shunt and having a bipolar maximum current comparator;
(c) monitoring means coupled to said two current detection and evaluation circuits for monitoring the maximum current, the mean current, the temperature, an auxiliary voltage, and having a timer, a reset and an indication amplifier;
(d) a microprocessor coupled to said monitoring means;
and
(e) an interface, and two control signal processing units coupled to said microprocessor, said two control signal processing units each having a Schmitt trigger, a frequency limiter, a transmitter driver, and transmitter arrestor;
whereas said semiconductor bridge circuit includes four transistors each with a module driver, two of said transistors forming a first branch of said bridge circuit and having their module drivers coupled to one of said two control signal processing units, the other two of said transistors forming a second branch of said bridge circuit and having their module drivers coupled to the other of said two control signal processing units;
and
whereas said microprocessor receives signals from said two current detection and evaluation circuits and said monitoring means and through said interface instructs said two control signal processing units to switch said first and second branches of said semiconductor bridge circuit on and off to control and regulate the plasma intensity.

11 more elements