US5900062A — Lift pin for dechucking substrates

Claim 1

Independent Claim 130 words

A lift pin for dechucking a substrate held to a chuck by residual electrostatic charge, the substrate being processed in a plasma formed using radio frequency currents, the lift pin comprising: (a) a movable elongated member having a tip suitable for lifting and lowering the substrate off the chuck, the movable elongated member providing an electrically conductive path between the substrate and a current sink when the tip contacts the substrate to allow the residual electrostatic charge to flow therethrough; and (b) the electrically conductive path of the movable elongated member comprising: (1) a frequency selective filter that reduces the amperage of radio frequency currents flowing therethrough; or (2) a resistor having a resistance sufficiently elevated to reduce a voltage of radio frequency currents flowing therethrough, by at least 50%.

Claim 2

Dependent Claim 130 words

A lift pin for dechucking a substrate held to a chuck by residual electrostatic charge, the substrate being processed in a plasma formed using radio frequency currents, the lift pin comprising: (a) a movable elongated member having a tip suitable for lifting and lowering the substrate off the chuck, the movable elongated member providing an electrically conductive path between the substrate and a current sink when the tip contacts the substrate to allow the residual electrostatic charge to flow therethrough; and (b) the electrically conductive path of the movable elongated member comprising: (1) a frequency selective filter that reduces the amperage of radio frequency currents flowing therethrough; or (2) a resistor having a resistance sufficiently elevated to reduce a voltage of radio frequency currents flowing therethrough, by at least 50%.

Claim 3

Dependent Claim 50 words

The lift pin of claim 1, wherein the elongated member comprises: (a) an electrically conductive upper portion suitable for lifting and lowering the substrate; (b) a central portion comprising the frequency selective filter or resistor; and (c) an electrically conductive lower portion suitable for electrical connection to the current sink.

Claim 4

Dependent Claim 38 words

The lift pin of claim 1, wherein the frequency selective filter conducts currents having first frequencies therethrough substantially without conducting currents having second frequencies therethrough, the second frequencies being at least 0.5 MHz higher than the first frequencies.

Claim 5

Dependent Claim 33 words

The lift pin of claim 1, wherein the frequency selective filter conducts currents having first frequencies of less than 100 Hz substantially without conducting currents having second frequencies of at least 1 MHz.

Claim 6

Dependent Claim 35 words

The lift pin of claim 3, wherein the frequency selective filter conducts at least 90% of the currents having the first frequencies therethrough and less than 10% of the currents having the second frequencies therethrough.

Claim 7

Dependent Claim 24 words

The lift pin of claim 1, wherein the frequency selective filter includes a low-pass filter having a cut-off frequency of less than 10 MHz.

Claim 8

Dependent Claim 26 words

The lift pin of claim 6, wherein the low-pass filter comprises an inductive circuit that includes a resistor having a resistance of at least 10 MΩ.

Claim 9

Dependent Claim 19 words

The lift pin of claim 6, wherein the cut-off frequency of the lowpass filter is less than 1 MHz.

Claim 10

Dependent Claim 37 words

The lift pin of claim 6, wherein the low-pass filter includes an inductive circuit having an impedance sufficiently high to discharge the residual electrostatic charge in the substrate to the current sink in less than 10 msec.

Claim 11

Dependent Claim 25 words

The lift pin of claim 8, wherein the inductive circuit comprises an inductor having an inductance of from about 10 μH to about 1000 μH.

Claim 12

Dependent Claim 31 words

The lift pin of claim 1, wherein the resistor has a resistance sufficiently high to discharge residual electrostatic charge in the substrate to the current sink in less than 10 msec.

Claim 13

Dependent Claim 17 words

The lift pin of claim 11, wherein the resistor has a resistance of at least 10 MΩ.

Claim 14

Dependent Claim 20 words

The lift pin of claim 12, wherein the resistor has a resistance of from about 10 to about 100 MΩ.

Claim 15

Dependent Claim 130 words

A lift pin for dechucking a substrate held to a chuck by residual electrostatic charge, the lift pin comprising; (a) a movable elongated member having a tip suitable for lifting and lowering the substrate off the chuck, the movable elongated member providing an electrically conductive path between the substrate and a current sink when the tip contacts the substrate to allow the residual electrostatic charge to flow therethrough; and (b) the electrically conductive path comprising: (1) a current limiter that reduces the amperage of a radio frequency current passing therethrough while allowing the residual electrostatic charge in the substrate to flow therethrough; or (2) a voltage reducer that reduces a voltage of a radio frequency current passing therethrough while allowing the residual electrostatic charge in the substrate to flow therethrough.

Claim 16

Dependent Claim 130 words

A lift pin for dechucking a substrate held to a chuck by residual electrostatic charge, the lift pin comprising; (a) a movable elongated member having a tip suitable for lifting and lowering the substrate off the chuck, the movable elongated member providing an electrically conductive path between the substrate and a current sink when the tip contacts the substrate to allow the residual electrostatic charge to flow therethrough; and (b) the electrically conductive path comprising: (1) a current limiter that reduces the amperage of a radio frequency current passing therethrough while allowing the residual electrostatic charge in the substrate to flow therethrough; or (2) a voltage reducer that reduces a voltage of a radio frequency current passing therethrough while allowing the residual electrostatic charge in the substrate to flow therethrough.

Claim 17

Dependent Claim 43 words

The lift pin of claim 14, wherein the current limiter comprises a frequency selective filter that conducts currents having first frequencies therethrough substantially without conducting currents having second frequencies therethrough, the second frequencies being at least 1 MHz higher than the first frequencies.

Claim 18

Dependent Claim 35 words

The lift pin of claim 15, wherein the frequency selective filter conducts at least 90% of the currents having the first frequencies therethrough and less than 10% of the currents having the second frequencies therethrough.

Claim 19

Dependent Claim 37 words

The lift pin of claim 14, wherein the current limiter includes an inductive circuit having an impedance sufficiently high to discharge the residual electrostatic charge in the substrate to the current sink in less than 10 msec.

Claim 20

Dependent Claim 25 words

The lift pin of claim 17, wherein the inductive circuit comprises an inductor having an inductance of from about 10 μH to about 1000 μH.

Claim 21

Dependent Claim 35 words

The lift pin of claim 14, wherein the voltage reducer comprises a resistor having a resistance sufficiently high to discharge residual electrostatic charge in the substrate to the current sink in less than 10 msec.

Claim 22

Dependent Claim 17 words

The lift pin of claim 19, wherein the resistor has a resistance of at least 10 MΩ.

Claim 23

Dependent Claim 20 words

The lift pin of claim 20, wherein the resistor has a resistance of from about 10 to about 100 MΩ.

Claim 24

Dependent Claim 160 words

A lift pin assembly for dechucking a substrate held to a chuck by residual electrostatic charge, the substrate processed in a plasma formed using radio frequency currents, the lift pin assembly comprising: (a) a support; (b) a plurality of elongated members mounted on the support, at least one elongated member comprising: (i) an electrically conductive upper portion suitable for contacting the substrate; (ii) an electrically conductive lower portion suitable for electrical connection to a current sink to allow the flow of the residual electrostatic charge from the substrate to the current sink; and (iii) a central portion comprising (1) a frequency selective filter that reduces the amperage of radio frequency currents flowing therethrough, or (2) a resistor having a resistance sufficiently elevated to reduce a voltage of radio frequency currents flowing therethrough by at least 50%; and (c) lift bellows that lift and lower the support so that the elongated members on the support can lift or lower the substrate.

Claim 25

Dependent Claim 160 words

A lift pin assembly for dechucking a substrate held to a chuck by residual electrostatic charge, the substrate processed in a plasma formed using radio frequency currents, the lift pin assembly comprising: (a) a support; (b) a plurality of elongated members mounted on the support, at least one elongated member comprising: (i) an electrically conductive upper portion suitable for contacting the substrate; (ii) an electrically conductive lower portion suitable for electrical connection to a current sink to allow the flow of the residual electrostatic charge from the substrate to the current sink; and (iii) a central portion comprising (1) a frequency selective filter that reduces the amperage of radio frequency currents flowing therethrough, or (2) a resistor having a resistance sufficiently elevated to reduce a voltage of radio frequency currents flowing therethrough by at least 50%; and (c) lift bellows that lift and lower the support so that the elongated members on the support can lift or lower the substrate.

Claim 26

Dependent Claim 45 words

The lift pin assembly of claim 22, wherein the frequency selective filter comprises a low-pass filter having a cut-off frequency of less than 10 MHz to allow substantially only currents having frequencies less than 10 MHz to flow from the substrate to the current sink.

Claim 27

Dependent Claim 38 words

The lift pin assembly of claim 23, wherein the low-pass filter includes an inductive circuit having an impedance sufficiently high to discharge the residual electrostatic charge in the substrate to the current sink in less than 10 msec.

Claim 28

Dependent Claim 26 words

The lift pin assembly of claim 24, wherein the low-pass filter includes an inductor having an inductance of from about 10 μH to about 1000 μH.

Claim 29

Dependent Claim 32 words

The lift pin assembly of claim 22, wherein the resistor has a resistance sufficiently high to discharge residual electrostatic charge in the substrate to the current sink in less than 10 msec.

Claim 30

Dependent Claim 18 words

The lift pin assembly of claim 26, wherein the resistor has a resistance of at least 10 MΩ.

Claim 31

Dependent Claim 141 words

A plasma process chamber comprising: (a) a gas distributor for distributing process gas in the process chamber; (b) a plasma generator for forming a plasma from the process gas using radio frequency currents; (c) an electrostatic chuck for holding a substrate in the plasma; and (d) a plurality of lift pins for lifting and lowering the substrate off the electrostatic chuck, at least one lift pin providing an electrically conductive path between the substrate and a current sink to allow the flow of residual electrostatic charge from the substrate to the current sink when the lift pin contacts the substrate, the electrically conductive path comprising a frequency selective filter that reduces the amperage of radio frequency currents flowing therethrough, or a resistor having a resistance sufficiently elevated to reduce a voltage of radio frequency currents flowing therethrough by at least 50%.

Claim 32

Dependent Claim 141 words

A plasma process chamber comprising: (a) a gas distributor for distributing process gas in the process chamber; (b) a plasma generator for forming a plasma from the process gas using radio frequency currents; (c) an electrostatic chuck for holding a substrate in the plasma; and (d) a plurality of lift pins for lifting and lowering the substrate off the electrostatic chuck, at least one lift pin providing an electrically conductive path between the substrate and a current sink to allow the flow of residual electrostatic charge from the substrate to the current sink when the lift pin contacts the substrate, the electrically conductive path comprising a frequency selective filter that reduces the amperage of radio frequency currents flowing therethrough, or a resistor having a resistance sufficiently elevated to reduce a voltage of radio frequency currents flowing therethrough by at least 50%.

Claim 33

Dependent Claim 34 words

The plasma process chamber of claim 28, wherein the radio frequency currents have frequencies of at least 1 MHz, and the residual electrostatic charges in the substrate have frequencies of less than 100 Hz.

Claim 34

Dependent Claim 45 words

The plasma process chamber of claim 28, wherein the frequency selective filter comprises a low-pass filter having a cut-off frequency of less than 10 MHz to allow substantially only currents having frequencies less than 10 MHz to flow from the substrate to the current sink.

Claim 35

Dependent Claim 39 words

The plasma process chamber of claim 30, wherein the frequency selective filter includes an inductive circuit having an impedance sufficiently high to discharge the residual electrostatic charge in the substrate to the current sink in less than 10 msec.

Claim 36

Dependent Claim 26 words

The plasma process chamber of claim 31, wherein the frequency selective filter includes an inductor having an inductance of about 10 μH to about 1000 μH.

Claim 37

Dependent Claim 32 words

The plasma process chamber of claim 28, wherein the resistor has a resistance sufficiently high to discharge residual electrostatic charge in the substrate to the current sink in less than 10 msec.

Claim 38

Dependent Claim 18 words

The plasma process chamber of claim 33, wherein the resistor has a resistance of at least 10 MΩ.

Claim 39

Independent Claim 104 words

A method of dechucking a substrate held to an electrostatic chuck by residual electrostatic charge, the substrate processed in a plasma formed using radio frequency currents, the method comprising the steps of: (a) discharging the residual electrostatic charge in the substrate to a current sink while reducing the voltage or amperage of the radio frequency currents flowing to the current sink by providing audio frequency voltage reduce or a radio frequency current limiter in an electrical pathway between the substrate and the current sink; and (b) lifting the substrate off the electrostatic chuck after the residual electrostatic charge in the substrate is substantially discharged.

Claim 40

Independent Claim 104 words

A method of dechucking a substrate held to an electrostatic chuck by residual electrostatic charge, the substrate processed in a plasma formed using radio frequency currents, the method comprising the steps of: (a) discharging the residual electrostatic charge in the substrate to a current sink while reducing the voltage or amperage of the radio frequency currents flowing to the current sink by providing audio frequency voltage reduce or a radio frequency current limiter in an electrical pathway between the substrate and the current sink; and (b) lifting the substrate off the electrostatic chuck after the residual electrostatic charge in the substrate is substantially discharged.

Claim 41

Dependent Claim 81 words

The dechucking method of claim 35, wherein the step of discharging the residual electrostatic charge in the substrate to the current sink comprises electrically connecting the substrate to the current sink by a current limiter that conducts radio frequency currents having first frequencies while reducing the amperage of radio frequency currents having second frequencies passing therethrough to allow the residual electrostatic charge in the substrate to flow therethrough, the second frequencies being at least 1 MHz higher than the first frequencies.

Claim 42

Dependent Claim 61 words

The dechucking method of claim 35, wherein the step of discharging the residual electrostatic charge in the substrate to the current sink comprises electrically connecting the substrate to a current sink using a voltage reducer that reduces a voltage of radio frequency currents flowing therethrough by at least 50% while allowing the residual electrostatic charge in the substrate to flow therethrough.

Claim 43

Dependent Claim 42 words

The dechucking method of claim 35, wherein step (b) is performed simultaneously with step (a), and wherein the residual electrostatic charge in the substrate is discharged to the current sink in a sufficiently short time that the substrate is dechucked without breaking.

Claim 44

Dependent Claim 30 words

The dechucking method of claim 38, wherein the step of discharging the residual electrostatic charge in the substrate to the current sink is performed in less than about 10 msec.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	2002-05-03	2002-11-02	2003-05-04	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	2006-05-03	2006-11-02	2007-05-04	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	2010-05-03	2010-11-02	2011-05-04	$7700.00	Window Closed / Lapsed

Lift pin for dechucking substrates

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