WO2003079427A1

WO2003079427A1 - Plasma processing method

Info

Publication number: WO2003079427A1
Application number: PCT/JP2003/002934
Authority: WO
Inventors: Tadashi Gondai
Original assignee: Tokyo Electron Limited
Priority date: 2002-03-19
Filing date: 2003-03-12
Publication date: 2003-09-25
Also published as: TW200306137A; TWI301731B

Abstract

A plasma processing method in which plasma can be fired stably with a low high frequency power and a low gas pressure even after long time operation by applying a DC voltage of -0.5 kV, for example, from a DC power supply (118) to a lower electrode (104) before a high frequency power is applied from a high frequency power supply (114) to the lower electrode (104) through a matching unit (112) when the surface of a wafer W mounted on the lower electrode (104) disposed in a processing container (102) is subjected to a specified plasma processing with plasma of a processing gas formed by applying a high frequency power to the processing gas introduced into the airtight processing container (102).

Description

Description Plasma processing method Technical field

The present invention relates to a plasma processing method, and more particularly to a plasma processing method capable of stably generating plasma even when an applied high frequency power is low. Background art

In a plasma process performed in a semiconductor manufacturing process, a liquid crystal display device manufacturing process, or the like, a processing gas is introduced into an airtight processing container provided with electrodes, and high-frequency power is applied to the electrodes to process the processing gas. Plasma is generated, and predetermined processing such as etching and film formation is performed on the surface of the object.

However, with the diversification of the manufacturing process, it may be necessary to perform the process under the condition that the high-frequency power applied to the electrode is low. In addition, if the plasma processing equipment is operated continuously for a long time in the product manufacturing process, foreign matter generated by the processing adheres to the inside of the plasma processing equipment, and plasma can be generated stably. May disappear.

The present invention has been made in view of the above-mentioned problems of the conventional plasma processing method, and has an object to stabilize even when a high-frequency power to be applied is low and after a long-time operation of the plasma processing apparatus. It is another object of the present invention to provide a new and improved plasma processing method capable of generating plasma. Disclosure of the invention

In order to solve the above problems, the present invention introduces a processing gas into an airtight processing container and applies high frequency power to form a plasma of the processing gas, and a predetermined process is performed on a processing surface of an object to be processed. A method of performing a plasma process, comprising: applying a DC voltage to an electrode disposed in the processing container and on which the object to be processed is mounted; and applying the DC voltage after applying the DC voltage. Applying high frequency power to the It is characterized by doing. According to this method, it is possible to stably generate plasma even when the applied high-frequency power is low and even with a processing apparatus in which foreign matter adheres after long-time use.

Further, the present invention is characterized in that the method has a step of cutting off the DC voltage during the formation of plasma after applying the high-frequency power. According to such a method, it is possible to minimize the influence of the DC voltage during the plasma processing of the object to be processed, and to apply the conventional processing conditions as they are.

Further, the invention is characterized in that the DC voltage is -0.5 kV or less as a ground reference.

Furthermore, the present invention is characterized in that the pressure in the processing container is 1 OmTorr or more and 2 OmTorr or less, and the high-frequency power is 50 W or more and 450 W or less.

Further, the present invention is characterized in that the pressure inside the processing container is 1 OmTorr or more and 25 mTorr or less, and the high ill wave power is 50 W or more and 200 W or less. Furthermore, the present invention is characterized in that the pressure in the processing container is 1 OmTorr or more and 3 OmTorr or less, and the high-frequency power is 50 W or more and 150 W or less.

In these regions, plasma ignition was difficult when no DC voltage was applied, but stable plasma ignition can be achieved by applying a DC voltage.

Also, the present invention provides a method for introducing a processing gas into an airtight processing container and applying high-frequency power to form a plasma of the processing gas, and performing a predetermined plasma processing on a processing surface of an object to be processed. Wherein a step of applying a DC voltage to a first electrode disposed in the processing container and on which the object to be processed is mounted, and after applying a DC voltage to the first electrode, Applying high frequency power for plasma formation to a second electrode different from the electrode; applying high frequency power for plasma formation to the second electrode; and then applying high frequency power for bias to the first electrode. It is characterized by having a process.

In addition, the present invention provides a process gas introduced into a hermetically sealed process vessel, and a high-frequency power is applied to form a plasma of the process gas. Applying a DC voltage to a first electrode disposed in the processing vessel and on which the object is placed, and applying a DC voltage to the first electrode. Applying a bias high-frequency power to the first electrode; and applying a bias high-frequency power to the first electrode, and then forming a plasma on a second electrode different from the first electrode. And a step of applying high-frequency power for use.

Further, the present invention provides a process gas introduced into an airtight process container, and a high-frequency power is applied to an antenna to form a plasma of the process gas, and a predetermined plasma process is performed on a process surface of an object to be processed. A method comprising: applying a DC voltage to an electrode disposed in the processing container and on which the object is placed; applying a DC voltage to the electrode; and applying high-frequency power for plasma formation to the antenna. Applying a high frequency power for plasma formation to the antenna and then applying a high frequency power for bias to the electrode after applying the high frequency power for plasma formation to the antenna.

Further, the present invention is characterized in that the application of the DC voltage is stopped during the formation of the plasma. BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a sectional view schematically showing a plasma etching apparatus according to an embodiment of the present invention.

FIG. 2 is a sectional view schematically showing a plasma etching apparatus according to another embodiment of the present invention. BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, preferred embodiments of a plasma processing method according to the present invention will be described in detail with reference to the accompanying drawings. Here, the present invention will be described using the plasma etching apparatus 100 shown in FIG. 1 as an example.

As shown in FIG. 1, the plasma etching apparatus 100 has, for example, a substantially cylindrical air-tight processing container 102 grounded, and the processing chamber 102 includes a semiconductor wafer W. A lower electrode 104 also serving as a mounting table for mounting The lower electrode 104 is maintained at a predetermined temperature by a temperature control mechanism (not shown) including a heater and a temperature measuring member embedded inside. A heat transfer gas supply mechanism (not shown) is provided between the semiconductor wafer W and the lower electrode 104, and a heat transfer gas (for example, He gas) is supplied from the heat transfer gas supply mechanism to a predetermined position. The semiconductor wafer W is configured to be supplied with pressure and to transmit heat from the lower electrode 104 to the semiconductor wafer W, so that the temperature of the semiconductor wafer W can be controlled.

An upper electrode 108 is provided so as to face the lower electrode 104, and is grounded via the processing container 102. In the present embodiment, high-frequency power is applied only to lower electrode 104, but high-frequency power may also be applied to upper electrode 108.

A gas introduction port 106 connected to a gas introduction system (not shown) is provided at the upper part of the processing vessel 102, and a plurality of gas discharge ports 109 provided in the upper electrode 108 are provided. The processing gas is introduced into the processing vessel 102. The process gas, for example, mixed gas of C ₄ F ₈ and CO and A r and 0 ₂ is used.

An exhaust pipe 110 connected to an exhaust mechanism (not shown) is provided at a lower portion of the processing vessel 102, and is exhausted through the exhaust pipe 110 so that the inside of the processing vessel 102 is exhausted. Is maintained at a specified pressure. A magnet may be provided outside both side walls of the processing container 102 to apply a magnetic field perpendicular to the electric field. In this case, it is preferable that the strength of the magnetic field of the magnet is configured to be variable.

The lower electrode 104 is connected to a high-frequency power supply 114 via a matching box 112 and a DC power supply 118 which is a feature of the present invention via a resistor 116. The resistor 116 acts as a filter for cutting off the high-frequency power from the high-frequency power supply 114. The frequency of the high-frequency power supply 114 is preferably from 10 MHz to 200 MHz, and may be, for example, 13.56 MHz. The DC power supply 118 is configured to apply a negative potential, for example, a potential of 0.5 kV to the lower electrode 104. A choke coil may be provided between the DC power supply 118 and the high-frequency power supply 114 to assist the interruption of the high-frequency power.

Electric power is supplied from the high-frequency power supply 114 and the DC power supply 118 to bring the processing gas introduced into the processing vessel 102 into a plasma state, and emit the gas near the lower electrode 104 between the electrodes. An object is etched by the energy of ions and radicals accelerated by the generated self-bias voltage.

Next, an operation in performing an etching process using the plasma etching apparatus 100 will be described. First, the semiconductor wafer W is placed on the lower electrode 104 in the processing container 102 and exhausted by an exhaust mechanism (not shown) through the exhaust pipe 110. Thereafter, a predetermined processing gas is introduced from the gas inlet 106 through the gas discharge port 109 at a predetermined flow rate into the processing container 102, and the pressure is adjusted to a predetermined pressure.

Subsequently, a DC voltage of, for example, 0.5 kV is applied to the lower electrode 104 from the DC power supply 118, and thereafter, for example, the frequency of 13.56 MHz is applied from the high frequency power supply 114. Apply high frequency power of z. The power applied from the high-frequency power supply 114 will be described later. By applying these DC voltage and high-frequency power, the processing gas in the processing container 102 is made into a plasma, and a predetermined etching process is performed on the surface of the processing object.

Next, the effect of the DC power supply 118 which is a feature of the present invention will be described. Bra Zuma etching apparatus 1 0 0, as the process gas, a mixed gas of CO and 0 ₂ gas and N _2, was form form the plasma at a pressure of various RF applied power, and the processing vessel. The results are shown in Table 1.

Here, five semiconductor wafers were processed continuously, and plasma was ignited stably when all plasma was ignited.When plasma was difficult to ignite during processing of one of five wafers, all plasma was not ignited. The case was X.

table 1

As shown in Table 1, the lower the pressure inside the processing vessel and the lower the high-frequency power, the more difficult it is for plasma to ignite. For example, at a pressure of 2 OmT or in that case, the plasma will not ignite unless high-frequency power is applied up to about 500 W, and at 5 OmT orr, the plasma will be ignited by 100 W of high-frequency power. The blank column is not implemented, but from the above tendency, it is judged that plasma ignition can be performed stably in this range.

On the other hand, if a DC voltage of 0.5 kV is applied before the high-frequency power is applied to the lower electrode 104, even if the pressure in the processing vessel 102 is 1 OmT 0 rr and the high-frequency power is 50 W, five semiconductor wafers It was confirmed that the plasma ignited in all of the cases. When the DC voltage was less than 0.4 kV, the plasma did not ignite on all five semiconductor wafers when the pressure in the processing vessel 102 was 1 Om Torr and the high frequency power was 50 W.

After the ignition of the plasma, the plasma was generated stably even if the power supply from the DC power supply 118 was cut off. In addition, the ignition of the plasma It is confirmed by adjusting the capacitance (not shown) that there is a matching state where the reflected wave becomes zero. Also, when you were use a mixed gas of C ₄ F ₈ and CO and A r and 0 ₂ as the processing gas, the capacitance value of the matching device 1 1 in 2 at the time alignment, due to the application of the DC voltage Since there is no significant change, the effect of applying a DC voltage to the plasma state is considered to be negligible. Therefore, plasma processing of the object to be processed can be performed in the same manner as when no DC voltage is applied.

As described above, when a processing gas is introduced into the hermetic processing container 102, the power is applied by the high-frequency power supply 114 to convert the processing gas into plasma, and a predetermined processing is performed on the surface of the processing target. When the pressure in the processing vessel 102 is 1 O m T 0 rr, and the power of the high-frequency power supply 114 is 50 W, the DC power supply 118 supplies a DC voltage of -0.5 kV. Since the high-frequency power is applied while the gas is energized, the plasma can be easily ignited even when the applied high-frequency power is as low as about 50 W. After the plasma is stabilized, the DC power supply may be cut off, so that the influence of the object on the plasma processing can be minimized.

In addition, by facilitating plasma ignition at low high-frequency power and low gas pressure, a plasma treatment method that can be used in processes under various conditions can be provided. In this state, plasma can be ignited, which has the effect of facilitating maintenance.

Next, FIG. 2 is a schematic cross-sectional view of a plasma etching apparatus 200 according to another embodiment of the present invention. In the plasma etching apparatus 200, components having substantially the same functional configuration as the plasma etching apparatus 100 shown in FIG. 1 are denoted by the same reference numerals, and description thereof is omitted.

The plasma etching apparatus 200 has a processing container 201, and the processing container 201 includes a processing container main body 202 having a bottomed cylindrical shape and is grounded for safety. A top plate 203 is hermetically attached to an upper opening of the processing container body 202 via an insulating member 204. As in the plasma etching apparatus 100 shown in FIG. 1, the top plate 203 is provided with an upper electrode 1 • 8 as a second electrode. A high-frequency power source 206 is connected to the top plate 203 via a matching device 205. In order to perform an etching process in such a plasma etching apparatus 200, First, similarly to the plasma etching apparatus 100 shown in FIG. 1, the wafer W is mounted on the lower electrode, which is the first electrode.

Next, a predetermined processing gas is introduced into the processing container 201, and the pressure is adjusted to a predetermined pressure.

Thereafter, a DC voltage of, for example, 0.5 kV is applied to the lower electrode 104 on which the wafer W is placed.

Next, a high frequency power for plasma formation having a frequency of, for example, 60 MHz is applied to the upper electrode 108.

Next, for example, high frequency power for bias having a frequency of 13.56 MHz is applied to the lower electrode 104.

After the plasma is formed, the application of a DC voltage of 0.5 kV to the lower electrode 104 is turned off.

The plasma ignition method may be as follows in addition to the above method. That is, for example, a DC voltage of 0.5 kV is applied to the lower electrode 104 on which the wafer W is placed.

Next, the lower electrode 104 has a frequency of 13, for example. Apply 56MHz bias high frequency power.

Next, a high frequency power for forming a plasma having a frequency of, for example, 60 MHz is applied to the upper electrode 108.

Further, the present invention is also applicable to a case where an inductively coupled plasma device provided with an antenna instead of the upper electrode 108 is used.

In this case, first, a DC voltage of, for example, 0.5 kV is applied to the electrode on which the wafer W is placed, and then high-frequency power for plasma formation, for example, having a frequency of 13.56 MHz, is applied to the antenna, and then the wafer is For example, a high frequency bias power having a frequency of 3.2 MHz is applied to the electrode on which W is placed. Then, the application of a DC voltage of 0.5 kV to the electrode on which the wafer W is placed after the plasma is formed is set to 0 FF.

As described above, according to the present invention, when the applied high frequency power is low, And a plasma processing method capable of stably generating a plasma even after operating the plasma processing apparatus for a long time.

Claims

The scope of the claims

1. A method for introducing a processing gas into an airtight processing container and applying high frequency power to form a plasma of the processing gas, and performing a predetermined plasma processing on a processing surface of an object to be processed,

Applying a DC voltage to an electrode disposed in the processing container and on which the object is placed;

After applying the DC voltage, applying high-frequency power to the electrode to which the DC voltage has been applied,

A plasma processing method comprising:

2. The plasma processing method according to claim 1, further comprising a step of interrupting the DC voltage during plasma formation after applying the high-frequency power.

3. The plasma processing method according to claim 1, wherein the DC voltage is −0.5 kV or less.

4. The pressure in the processing container is 1 OmT orr or more and 2 OmT orr or less, and the high frequency power is 50 W or more and 450 W or less, any one of claims 1 to 3 characterized by the above-mentioned. Item 6. The plasma processing method according to item 1.

5. The pressure in the processing container is 1 OmT or more and 25 mT or less or less, and the high frequency power is 50 W or more and 200 W or less, any one of claims 1 to 3 characterized by the above-mentioned. 4. The plasma processing method according to 1.

6. The pressure in the processing container is 1 OmT 0 rr or more and 3 OmT orr or less, and the high frequency power is 50 W or more and 150 W or less, any one of claims 1 to 3, wherein Item 2. The plasma processing method according to item 1.

7. A method of introducing a processing gas into an airtight processing container and applying high-frequency power to form a plasma of the processing gas, and performing a predetermined plasma processing on a processing surface of an object to be processed,

Applying a DC voltage to a first electrode disposed in the processing container and on which the object is placed;

After applying a DC voltage to the first electrode, applying a high-frequency power for plasma formation to a second electrode different from the first electrode,

Applying high frequency power for bias to the first electrode after applying high frequency power for plasma formation to the second electrode;

A plasma processing method characterized by comprising:

8. A method of introducing a processing gas into an airtight processing container and applying high-frequency power to form a plasma of the processing gas, and performing a predetermined plasma processing on a processing surface of an object to be processed,

Applying a high-frequency power for bias to the first electrode after applying a DC voltage to the first electrode;

After applying a high frequency power for bias to the first electrode, a step of applying high frequency power for plasma formation to a second electrode different from the first electrode;

A plasma processing method characterized by comprising:

9. A method in which a processing gas is introduced into an airtight processing container and high-frequency power is applied to an antenna to form a plasma of the processing gas, and a predetermined plasma processing is performed on a processing surface of an object to be processed. ,

After applying a DC voltage to the electrode, a high frequency power for plasma formation is applied to the antenna. Applying,

Applying high-frequency power for bias to the electrode after applying high-frequency power for plasma formation to the antenna;

A plasma processing method characterized by comprising:

10. The plasma processing method c according to any one of claims 7 to 9, wherein the application of the DC voltage is stopped during the formation of the plasma.