JPH0774144A - Cleaning method for plasma apparatus - Google Patents

Abstract

PURPOSE:To provide a cleaning method to effectively eliminate chlorine element from a processing chamber of a plasma apparatus. CONSTITUTION:For the cleaning of an RIE apparatus 1 for etching wafers 5 in the chloric gas ambient introduced from a gas introducing pipe 9, fluoric gas is first introduced from a gas introducing gas pipe 10 and a voltage is applied to an etching changer 2 for the discharging dissociation of fluoric gas. Thereby, the chloric gas in the etching chamber 2 can be eliminated. Thereafter, the etching chamber 2 is exposed to the atmospheric condition to eliminate reaction product deposited by an organic solvent.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of cleaning a plasma device for performing a plasma treatment using plasma obtained by dissociating a chlorine-based gas by electric discharge.

[0002]

2. Description of the Related Art In the field of semiconductor device manufacturing, a typical example of plasma treatment using plasma obtained by dissociating chlorine gas by discharge is reactive ion etching (RIE) of an Al-based material layer. Specifically, it is used when forming a wiring by processing a predetermined region of an Al film formed on a silicon substrate by RIE.

When the above-described RIE processing is performed, solid chlorine remaining on the inner wall surface of the etching chamber of the RIE apparatus and internal components such as the wafer clamp, that is, CCl _x derived from decomposition products of the resist mask. Chlorine reaction products such as polymers are deposited. When this chlorine-based reaction product is re-sputtered during the next etching, it adheres to the Al film to be originally etched, deteriorating the reproducibility of etching and contaminating the element.

Therefore, in order to improve the reproducibility of etching and reduce dust in the etching chamber, the inside of the etching chamber is regularly cleaned with an organic solvent such as alcohol.

[0005]

By the way, in order to perform the above cleaning, the etching chamber must first be opened to the atmosphere. However, in the etching chamber immediately after etching, in addition to the chlorine-based reaction product, gas-phase residual chlorine, that is, chlorine-based gas also exists,
It is dangerous to open the etching chamber in this state. Therefore, it is necessary to remove the residual chlorine in the gas phase, that is, the chlorine-based gas, before opening the etching chamber.

As a method for removing the chlorine-based gas,
Plasma discharge by O ₂ gas is performed in the etching chamber where etching is completed, and vacuum exhaust is performed. However, it is the current situation that the chlorine-based gas cannot be removed sufficiently even by this treatment, and when the etching chamber is opened, there are many cases that there is a pungent odor and a chlorine gas leak detector reports.

[0007] This chlorine compounds or chlorine-based gas of the low-molecular to CCl _x polymers are chlorinated reaction products deposited on the internal components of the etch chamber have been occluded, the chlorine compounds and CCl _x polymers It is thought that this is because the chlorine is decomposed to generate a chlorine-based gas, or the occluded chlorine-based gas is gradually released.

Then, the above-mentioned RI for Al etching is used.
Not only the E apparatus, but also the plasma apparatus that performs plasma processing using a chlorine-based gas similarly poses a problem of removing the chlorine-based gas.

Therefore, the present invention has been proposed in view of such conventional circumstances, and an object thereof is to provide a cleaning method for a plasma device which effectively removes chlorine components from the inside of a processing chamber of the plasma device. .

[0010]

SUMMARY OF THE INVENTION The present invention has been proposed to achieve the above-mentioned object, and a predetermined amount of plasma is generated by dissociating chlorine-based gas in a processing chamber of a plasma apparatus. After the plasma treatment, the gas phase residual chlorine in the processing chamber is removed by using plasma formed by dissociating the fluorine-based gas by electric discharge, and then the solid phase residual chlorine in the processing chamber is removed. .

[0011]

[Function] Fluorine-based gas is a halogen-based gas like chlorine-based gas, but fluorine ion is more reactive than chlorine-ion gas. Therefore, when chloride is plasma-discharged in fluorine-based gas, chloride will be discharged. Change to a compound. Therefore, for example, when the Al film is subjected to RIE processing and then plasma-discharged in a fluorine-based gas, chlorine-based reaction products such as CCl _x polymer deposited on the internal constituent members of the etching chamber discharge-dissociate the fluorine-based gas. The generated plasma changes into CF _x having a high vapor pressure. The chlorine-based gas stored in the CCl _x polymer is also replaced with the fluorine-based gas having a small molecular weight.

Therefore, the chlorine-based gas in the etching chamber is greatly reduced, and even when the etching chamber is opened, no irritating odor is produced and the chlorine gas leakage detector does not give a warning. That is, the safety is improved.

Further, by plasma-discharging in the above-mentioned fluorine-based gas, chlorine-based reaction products deposited on the internal components of the etching chamber can be easily removed, and chamber cleaning with an organic solvent can be facilitated. Time can be shortened. In this way, by thoroughly cleaning the inside of the etching chamber,
It is possible to improve the reproducibility of etching and reduce the contamination of the device.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Specific embodiments to which the present invention is applied will be described below with reference to the drawings.

In this embodiment, a method of cleaning an RIE device for processing an Al film for wiring will be described.

As shown in FIG. 1, the RIE apparatus 1 has
The etching chamber 2 includes a load lock chamber 3 connected to the etching chamber 2 via a gate valve 6, and an unload lock chamber 4 connected to the etching chamber 2 via a gate valve 7. Inside the etching chamber 2, an exhaust port 8 for exhausting the inside, a gas introducing pipe 9 for introducing a chlorine-based gas, and a gas introducing pipe 10 for introducing a fluorine-based gas are provided. In this RIE apparatus 1, ten wafers 5 can be placed and batch processed.

The RIE having the above-mentioned structure
Etching was performed by the apparatus 1 as follows. First, after opening the gate valve 6 and placing the wafer 5 from the load lock chamber 3 at a predetermined position in the etching chamber 2, the gate valve 6 was closed. Next, the gas introduction pipe 9
More chlorine-based gas was introduced.

The chlorine-based gas to be introduced is Cl
_Two gases, BCl ₃ gas, CHCl ₃ gas, etc. may be used alone or in combination.

Further, with the wafer stage on which the wafer 5 is placed as the lower electrode and the lid of the etching chamber 2 facing this as the upper electrode, an RF electric field is applied between the electrodes.
The chlorine-based gas was discharged and dissociated to generate plasma. A formed on the wafer 5 by this plasma
The predetermined region of the l film is etched. The wafer 5 after the etching was collected from the gate valve 7 into the unload lock chamber 4.

When the wafer 5 is etched as described above, chlorine-based reaction products are deposited on the internal constituent members of the etching chamber 2. Therefore, the etching chamber 2 is cleaned after performing a predetermined number of etchings. There is a need. Therefore, in the present embodiment, the etching chamber 2 is used for cleaning or other maintenance.
Before opening to the atmosphere, the following operation for removing chlorine-based gas was performed.

First, the valve (not shown) of the gas introducing pipe 9 is closed to stop the introduction of chlorine gas, the wafer 5 is recovered into the unload lock chamber 4, and then the gas introducing pipe 10 is closed.
More fluorine-based gas was introduced.

As the fluorine-based gas, CF_FourMoth
Su, C₂F₆Gas, NF₃Gas, SF ₆Gas alone or
Alternatively, they may be mixed and used. In this embodiment, CF
_FourGas was used.

Next, by applying an RF electric field in the etching chamber 2, the fluorine-based gas was discharged and dissociated to generate plasma. By this plasma treatment,
The reaction products such as CCl _x polymer deposited in the etching chamber 2 and the chlorine-based gas stored therein are changed or replaced by fluorides and discharged from the exhaust port 8. In this way, the chlorine-based gas was removed from the etching chamber 2.

Here, in order to investigate the chlorine-based gas removing effect of the above-mentioned treatment, the above-mentioned treatment was carried out for various treatment times, and changes in the chlorine-based gas concentration in the etching chamber 2 were measured. FIG. 2 shows the result as a relation between the cleaning time and the chlorine gas concentration.

From FIG. 2, it can be seen that the chlorine gas concentration decreases with the plasma processing time. Specifically, if the plasma treatment time is too short, the chlorine gas concentration will exceed the range of 5 ppm and the range will be exceeded, but if the plasma treatment is performed for about 10 minutes, the chlorine gas concentration will be approximately 0 ppm.

Therefore, when the etching chamber was opened to the atmosphere after the plasma treatment with the fluorine-based gas for 10 minutes or longer, no irritating odor was produced or the gas leak detector did not report. Further, when the inside was cleaned with an organic solvent, the chlorine-based reaction product deposited on the internal constituent members of the etching chamber could be easily removed.

As described above, the chlorine-based gas can be removed by performing the plasma treatment using the fluorine-based gas, and thereafter, the chlorine-based reaction product deposited on the internal constituent members of the etching chamber by the cleaning with the organic solvent is performed. Things could be removed. Therefore, by applying the cleaning method of the present invention, the RIE device could be sufficiently cleaned.

Although the example of cleaning the Al film etching RIE apparatus by the plasma treatment using the fluorine-based gas has been described above, the present invention can be applied as a cleaning method for an etching apparatus for polycrystalline silicon or a CVD apparatus. Is.

[0029]

As is apparent from the above description, when the plasma apparatus using the plasma of chlorine-based gas is cleaned by the plasma processing with the fluorine-based gas, the chlorine component in the processing chamber can be significantly reduced, so that the processing chamber is When it is opened, there will be no irritating odor, and the chlorine gas leak detector will no longer report. That is, it is possible to improve safety.

Further, by performing the plasma discharge with the fluorine-based gas, the cleaning with the organic solvent in the processing chamber becomes easy, so that the sufficient cleaning becomes possible. Therefore, the plasma device to which the present invention is applied for cleaning can reduce the contamination of the element and can be processed with high reproducibility. Furthermore, since the maintenance time is shortened, the operating rate of the plasma device can be increased and the productivity can be improved.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a configuration of an RIE device for etching an Al film to which a cleaning method of the present invention is applied.

FIG. 2 is a characteristic diagram showing the relationship between the cleaning time and the concentration of chlorine gas remaining in the etching chamber.

[Explanation of symbols]

 1 ... RIE device 2 ... Etching chamber 3 ... Load lock chamber 4 ... Unload lock chamber 5 ... Wafer 6,7 ... Gate valve 8 ... Exhaust port 9,10 ... ..Gas introduction pipes

Claims (1)

[Claims] 1. A treatment chamber of a plasma apparatus, wherein a predetermined plasma treatment is performed by using plasma obtained by dissociating chlorine-based gas by discharge, and then the treatment chamber is performed by using plasma obtained by discharge-dissociating fluorine-based gas. A method for cleaning a plasma apparatus, comprising removing residual chlorine in a gas phase inside the chamber, and then removing residual chlorine in a solid phase inside the processing chamber.