Plasma processing method

Patent metadata

Field	Value
Publication number	US-9953811-B2
Application number	US-201414325457-A
Country	US
Kind code	B2
Filing date	Jul 8, 2014
Priority date	Mar 29, 2011
Publication date	Apr 24, 2018
Grant date	Apr 24, 2018

Abstract

A plasma processing method for performing a plasma process on a processing target substrate is provided. The plasma processing method includes: segmenting a RF antenna into an inner coil, an intermediate coil, and an outer coil with gaps therebetween in a radial direction, respectively, the inner coil, the intermediate coil and the outer coil being electrically connected to one another in parallel between a first node and a second node; providing a variable intermediate capacitor and a variable outer capacitor between the first node and the second node, the variable intermediate capacitor being electrically connected in series to the intermediate coil, the variable outer capacitor being electrically connected in series to the outer coil, no reactance device being connected to the inner coil; and controlling plasma density distribution on the processing target substrate by selecting or variably adjusting electrostatic capacitances of the intermediate capacitor and the outer capacitor.

First claim

What is claimed is:

1. A plasma processing method for performing a plasma process on a processing target substrate by using a plasma processing apparatus having a processing chamber having a dielectric window; a substrate holding unit for holding thereon a processing target substrate within the processing chamber; a processing gas supply unit configured to supply a processing gas into the processing chamber in order to perform a plasma process on the processing target substrate; an RF antenna provided outside the dielectric window in order to generate plasma of the processing gas within the processing chamber by inductive coupling; and a high frequency power supply unit configured to supply a high frequency power having a frequency for generating a high frequency electric discharge of the processing gas in the RF antenna, the plasma processing method comprising:
segmenting the RF antenna into an inner coil, an intermediate coil, and an outer coil with gaps therebetween in a radial direction, respectively, the inner coil, the intermediate coil and the outer coil being electrically connected to one another in parallel between a first node and a second node provided in high frequency transmission lines of the high frequency power supply unit;
providing a variable intermediate capacitor and a variable outer capacitor between the first node and the second node, the variable intermediate capacitor being electrically connected in series to the intermediate coil, the variable outer capacitor being electrically connected in series to the outer coil, no reactance device being connected to the inner coil; and
controlling plasma density distribution on the processing target substrate by selecting or variably adjusting electrostatic capacitances of the variable intermediate capacitor and the variable outer capacitor such that increased amounts of coil currents by the variable intermediate capacitor and the variable outer capacitor flow only in the intermediate coil and the outer coil,
wherein when the number of windings of the inner coil and the number of windings of the outer coil are N i and N o , respectively, an impedance of the inner coil is Z i , and a maximum value and a minimum value of a combined impedance of the outer coil and the outer capacitor obtained by varying an electrostatic capacitance of the outer capacitor are Z o ( max ) and Z o ( min ), respectively, the following equation is established:
| N o /Z o(max) |<|N i /Z i |<|N o /Z o(min) |.

2. The plasma processing method of claim 1 ,
wherein the current flowing in the inner coil is reduced by making at least one of electrostatic capacitances of the intermediate capacitor and the outer capacitor close to a value when a series resonance is generated.

3. The plasma processing method of claim 1 ,
wherein the current flowing in the inner coil is increased by making at least one of electrostatic capacitances of the intermediate capacitor and the outer capacitor apart from a value when a series resonance is generated.

4. The plasma processing method of claim 1 ,
wherein electrostatic capacitances of the intermediate capacitor and the outer capacitor are adjusted to enable plasma density on the processing target substrate to be uniformized in a diametrical direction.

5. The plasma processing method of claim 1 ,
wherein the plasma density on the processing target substrate is adjusted so as to be uniformized in the diametrical direction by conforming multiplication of the number of turns of each of the intermediate coil and the outer coil and an amount of a coil current thereof to multiplication of the number of turns of the inner coil and an amount of a coil current thereof.

6. The plasma processing method of claim 1 ,
wherein a direction of the current flowing in the intermediate coil is opposite to a direction of the current flowing in the inner coil in the circumferential direction by variably adjusting the electrostatic capacitance of the intermediate capacitor in a range smaller than a value when the intermediate capacitor and the intermediate coil generate a series resonance.

7. The plasma processing method of claim 1 ,
wherein a direction of the current flowing in the intermediate coil is identical to a direction of the current flowing in the inner coil in the circumferential direction by variably adjusting the electrostatic capacitance of the intermediate capacitor in a range larger than a value when the intermediate capacitor and the intermediate coil generate a series resonance.

8. The plasma processing method of claim 1 ,
wherein a direction of the current flowing in the outer coil is opposite to a direction of the current flowing in the inner coil in the circumferential direction by variably adjusting the electrostatic capacitance of the outer capacitor in a range smaller than a value when the outer capacitor and the outer coil generate a series resonance.

9. The plasma processing method of claim 1 ,
wherein a direction of the current flowing in the outer coil is identical to a direction of the current flowing in the inner coil in the circumferential direction by variably adjusting the electrostatic capacitance of the outer capacitor in a range larger than a value when the outer capacitor and the outer coil generate a series resonance.

Assignees

• Tokyo Electron Ltd

Inventors

• Yamazawa Yohei

Classifications

• H01J37/32174

  Circuits specially adapted for controlling the RF discharge · CPC title

• H01J37/321

  the radio frequency energy being inductively coupled to the plasma · CPC title

• H01J37/32137

  controlling of the discharge by modulation of energy · CPC title

• H01J37/32697 Primary

  Electrostatic control · CPC title

• H01J2237/3341

  Reactive etching · CPC title