US-12626893-B2 - Plasma processing apparatus and plasma processing method

US12626893B2US 12626893 B2US12626893 B2US 12626893B2US-12626893-B2

Abstract

The plasma processing apparatus includes a chamber body, a stage, a gas supply mechanism, a DC power supply, a radio-frequency power supply, and a controller. The gas supply is configured to supply a heat transfer gas to the upper surface of the electrostatic chuck. The controller is configured to control the DC power supply. The controller controls the DC power supply to apply, to the electrostatic chuck, a voltage derived by combining an output of a first function that outputs a smaller value as the absolute value of a self-bias voltage generated according to the plasma becomes larger and an output of a second function that outputs a larger value as the pressure of the heat transfer gas supplied to the upper surface of the electrostatic chuck by the gas supply increases.

Inventors

Chishio Koshimizu

Assignees

TOKYO ELECTRON LIMITED

Dates

Publication Date: 20260512
Application Date: 20231213
Priority Date: 20180406

Claims (10)

1 . A plasma processing apparatus comprising: a chamber; an electrostatic chuck provided in the chamber and configured to hold a substrate, the electrostatic chuck having a gas supply line; a gas supply configured to supply a heat transfer gas to a space between the electrostatic chuck and the substrate via the gas supply line; a DC power supply configured to apply a voltage to the electrostatic chuck; a plasma generator configured to generate plasma in the chamber; a self-bias voltage meter configured to measure a self-bias voltage generated according to the plasma; a pressure detector configured to detect a pressure of the heat transfer gas supplied via the gas supply line; and a controller configured to determine a voltage applied to the electrostatic chuck based on an absolute value derived from an output of the self-bias voltage meter, and an output of the pressure detector, the voltage applied to the electrostatic chuck decreasing as the absolute value increases.
2 . The plasma processing apparatus according to claim 1 , wherein the controller determines the voltage such that the voltage becomes larger as the pressure of the heat transfer gas becomes larger.
3 . The plasma processing apparatus according to claim 1 , wherein the self-bias voltage meter is provided in a path where radio-frequency waves are applied from the plasma generator to the chamber.
4 . The plasma processing apparatus according to claim 3 , wherein the controller is configured to control the DC power supply such that, after the radio frequency waves are applied to the chamber by the plasma generator, voltage application to the electrostatic chuck is started at a first timing when the temperature detected by the detector is equal to or higher than a predetermined temperature threshold, at a second timing when an expected time when the temperature of the substrate becomes equal to or higher than the predetermined temperature threshold is elapsed, or at an earlier one of the first timing and the second timing.
5 . The plasma processing apparatus according to claim 4 , wherein the controller is configured to control the gas supply such that supply of the heat transfer gas is started at the same timing as the voltage application by the DC power supply or after a predetermined time has elapsed.
6 . The plasma processing apparatus according to claim 4 , wherein the controller is configured to control the gas supply such that the pressure of the heat transfer gas becomes equal to or lower than a predetermined heat transfer gas threshold.
7 . The plasma processing apparatus according to claim 4 , wherein the controller is configured to control the gas supply such that the pressure of the heat transfer gas increases with a lapse of time.
8 . The plasma processing apparatus according to claim 4 , wherein the temperature threshold is a value obtained by multiplying a target temperature of the substrate stored in advance as recipe data, by a predetermined constant.
9 . The plasma processing apparatus according to claim 1 , further comprising: a detector configured to detect a temperature of the substrate held on the electrostatic chuck or a temperature correlated with the temperature of the substrate, wherein the controller is configured to control a voltage application timing by the DC power supply based on the temperature detected by the detector.
10 . A plasma processing apparatus comprising: a chamber; a lower electrode provided in the chamber; an electrostatic chuck provided on the lower electrode and configured to hold a substrate, the electrostatic chuck having a gas supply line; a gas supply configured to supply a heat transfer gas to a space between the electrostatic chuck and the substrate via the gas supply line; a DC power supply configured to apply a voltage to the electrostatic chuck; a plasma generator configured to generate plasma in the chamber; a self-bias voltage meter configured to measure a self-bias voltage generated according to the plasma; a pressure detector configured to detect a pressure of the heat transfer gas supplied via the gas supply line; and a controller configured to determine a voltage applied to the electrostatic chuck based on an absolute value derived from an output of the self-bias voltage meter and an output of the pressure detector, the voltage applied to the electrostatic chuck decreasing as the absolute value increases, wherein the controller is configured to control the gas supply and the DC power supply such that an application of the voltage to the electrostatic chuck and a supply of the heat transfer gas to the space are simultaneously started after radio-frequency waves are applied from the plasma generator to the lower electrode.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS This application is a continuation application of U.S. patent application Ser. No. 16/375,917, filed on Apr. 5, 2019, which claims from Japanese Patent Application No. 2018-073872 filed on Apr. 6, 2018 with the Japan Patent Office, all of which are incorporated herein in their entireties by reference. TECHNICAL FIELD Embodiments of the present disclosure relate to a plasma processing apparatus and a plasma processing method. BACKGROUND In the manufacture of electronic devices, a plasma processing is performed for processing a substrate using a plasma processing apparatus. The plasma processing apparatus generally includes a chamber body, a stage, and a radio-frequency power supply. The chamber body provides an internal space as a chamber and the stage is provided in the chamber. The stage includes a lower electrode and an electrostatic chuck provided on the lower electrode. A radio-frequency power supply is connected to the lower electrode. In the plasma processing, the temperature of a workpiece rises due to the heat input from plasma. Therefore, the plasma processing apparatus includes a cooling mechanism for cooling the workpiece. For example, the electrostatic chuck includes a plurality of heat transfer gas supply holes that are open towards a workpiece attracted thereto. The electrostatic chuck holds the workpiece and supplies the heat transfer gas from the heat transfer gas supply holes to the rear surface of the workpiece, thereby suppressing the temperature rise of the workpiece. Such a plasma processing apparatus is described in, for example, Japanese Patent Laid-open Publication No. 2011-198838. When raising the voltage applied to the electrostatic chuck by gradually changing the voltage, the apparatus of Japanese Patent Laid-open Publication No. 2011-198838 controls the pressure of the heat transfer gas supplied from the heat transfer gas supply holes, thereby performing a control such that the force to separate the workpiece from the attraction force of the electrostatic chuck does not exceed the electrostatic force of the electrostatic chuck. SUMMARY In an aspect, a plasma processing apparatus is provided. The plasma processing apparatus includes a chamber body, a stage, a gas supply, a DC power supply, a radio-frequency power supply, and a controller. The chamber body provides a chamber. The stage is provided in the chamber, and has an electrostatic chuck. The gas supply is configured to supply a heat transfer gas to the upper surface of the electrostatic chuck. The DC power supply is configured to apply a voltage to the electrostatic chuck. The radio-frequency power supply is configured to supply radio-frequency waves for generating plasma of the gas in the chamber to an electrode provided in the chamber. The controller is configured to control the DC power supply. The controller controls the DC power supply to apply, to the electrostatic chuck, a voltage derived by combining an output of a first function that outputs a smaller value as the absolute value of a self-bias voltage generated according to the plasma becomes larger and an output of a second function that outputs a larger value as the pressure of the heat transfer gas supplied to the upper surface of the electrostatic chuck by the gas supply increases. The foregoing summary is illustrative only and is not intended to be in any way limiting. In addition to the illustrative aspects, embodiments, and features described above, further aspects, embodiments, and features will become apparent by reference to the drawings and the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a view schematically illustrating a plasma processing apparatus according to an embodiment. FIG. 2 is a partially enlarged sectional view of the stage and the focus ring illustrated in FIG. 1. FIG. 3 is a view illustrating an exemplary self-bias voltage measurement device capable of being adopted in the plasma processing apparatus illustrated in FIG. 1. FIG. 4 is a graph representing the time dependency of a substrate temperature. FIG. 5 is a flowchart illustrating a plasma processing method according to an embodiment. DETAILED DESCRIPTION In the following detailed description, reference is made to the accompanying drawing, which form a part hereof. The illustrative embodiments described in the detailed description, drawing, and claims are not meant to be limiting. Other embodiments may be utilized, and other changes may be made without departing from the spirit or scope of the subject matter presented here. In an aspect, a plasma processing apparatus is provided. The plasma processing apparatus includes a chamber body, a stage, a gas supply, a DC power supply, a radio-frequency power supply, and a controller. The chamber body provides a chamber. The stage is provided in the chamber, and has an electrostatic chuck. The gas supply is configured to supply a heat transfer gas to the upper surface of the