JP2000091327A - Method and device for cleaning plasma treating device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make a dust generating source removable by performing plasma cleaning, in such a way that the resulted product of an etching reaction is removed by using the plasma of a gas, and a film is deposited on the internal wall surface of an etching treating chamber by decomposing the gas which is introduced to the chamber after generating the plasma. SOLUTION: When plasma cleaning is performed by using oxygen gas as a first step, a film 15 which is formed of the resulted product of an etching reaction deposited on the wall surface 2 of an etching treating chamber is decomposed into carbon monoxide, carbon dioxide, and steam and removed by evacuation. When plasma is generated in the atmosphere of a mixed gas which is improved in depositing property and composed of carbon tetrafluoride and argon as a second step, a thin film 18 of a carbon compound is formed on the wall surface 2. Since a thin film 18 functions as a protective film for preventing the wall surface 2 from sputtering, the formation of a deposited film 16 caused by a sputtered material can be prevented. Therefore, a deposited film which becomes a source for generating foreign matter and adheres to the inside wall surface of an etching treatment chamber can be removed effectively.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to cleaning of a plasma processing apparatus having a function of performing dry cleaning in a processing chamber of a semiconductor manufacturing apparatus used for performing fine processing on a substrate in a semiconductor device manufacturing process. About the method.

[0002]

2. Description of the Related Art In the manufacturing process of a semiconductor device, if dust (foreign matter) adheres to a substrate, pattern defects of a target device are caused, and the yield in the manufacturing process is reduced. On the other hand, in microfabrication in recent manufacturing processes,
A dry etching process using plasma has become important. That is, various gases are introduced into the apparatus, and etching is performed utilizing the reaction of the plasma of the introduced gases.

[0003] In such a process, products generated by etching are deposited as deposited films everywhere on the inner wall of the apparatus.

That is, in dry etching, an etching gas is decomposed or combined in plasma, and a deposited film adheres to an inner wall of the apparatus due to an etching by-product generated by etching. When the number of processed films is increased and the film thickness is increased, such a deposited film is partially peeled off and becomes dust, resulting in a defect in a device pattern. Therefore, it is necessary to periodically remove these deposits.

Conventionally, as a method for removing such deposits, a so-called wet cleaning, in which the apparatus is opened to the atmosphere and wiped using a solvent such as alcohol or pure water,
2. Description of the Related Art Plasma cleaning using plasma for cleaning is known. As an example of the plasma cleaning method, for example, Japanese Patent Application Laid-Open No. 5-144779 is disclosed.

[0006]

However, the above conventional cleaning method has the following problems.

First, regarding wet cleaning,
Since the device needs to be opened to the atmosphere and disassembled, vacuum evacuation after wet cleaning is required. Therefore, the apparatus is stopped for a long time for each cleaning, which causes a remarkable reduction in apparatus operation rate and a reduction in throughput.

Japanese Patent Application Laid-Open No. 5-144779 is characterized in that a silicon halide is intentionally deposited on the inner wall of the processing chamber, and the deposited film formed by the etching reaction is covered with the silicon halide to make it difficult to peel off. Has become. The thickness of the deposited film on the wall surface of the processing chamber has various values depending on the processing conditions, that is, the type and flow rate of the gas, whether or not the added gas is mixed, the pressure, the input power to the plasma, and the like. In addition, the deposited film does not adhere uniformly in the processing chamber, and depending on conditions, there may be a case where a portion of the processing chamber wall is etched.

The above-mentioned prior art is effective when the deposited film formed by the etching reaction is relatively thin. However, since the deposited film is basically overcoated, a deposited film thicker than that in a normal use state of the apparatus is required. Will be formed. The internal stress of the deposited film increases with the film thickness, and the deposited film is easily cracked with the increase of the internal stress. Therefore, it is effective in a short term, but it cannot be expected to maintain a dramatic effect. In addition, high-selectivity etching, which is becoming mainstream recently, uses etching conditions with extremely high deposition properties, that is, conditions in which a deposited film is thick and easily deposited on the inner wall of the processing chamber. The conventional method of forming a deposited film has a problem that a foreign matter suppressing effect cannot be expected.

SUMMARY OF THE INVENTION An object of the present invention is to solve these problems and to effectively remove a deposited film adhered to an inner wall of a manufacturing apparatus, that is, to clean a plasma processing apparatus capable of removing a source of dust. It is to provide a method.

[0011]

The object of the present invention is to provide a plasma cleaning process in which a plasma cleaning process uses a plasma of a gas for removing an etching reaction product, and a process chamber in which the introduced gas is decomposed by generating the plasma. The second step of forming a deposited film on the wall surface is achieved.

Further, the above object is achieved by arbitrarily selecting and setting how many times the plasma cleaning process is to be performed and how long the cleaning process is to be performed in the continuous processing process.

The above object is achieved by performing a plasma cleaning process before the start of the continuous processing step.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings, taking etching of a silicon oxide film as an example.

FIG. 1 shows a commonly used parallel plate type plasma etching apparatus for explaining an embodiment of the present invention. 2 and 3 are schematic diagrams showing the state of the wall surface at that time. In FIG. 1, reference numeral 1 denotes a substrate to be subjected to an etching process, here, a silicon wafer; 2, an etching chamber; 3, an upper electrode;
Is an insulating plate for fixing the upper electrode, 5 is a lower electrode for loading the wafer, 6 is a susceptor for placing the wafer at a predetermined position, and 7 and 8 are gas introduction tubes for introducing an etching gas into the etching chamber. A shower hole 9 for diffusing into the chamber is an exhaust port for reducing the pressure in the etching chamber to a vacuum atmosphere and keeping the pressure at a constant level.

In the plasma etching apparatus configured as described above, first, the wafer 1, which is a substrate to be processed, is carried in, and a plasma gas to be generated is introduced into the chamber 2 through the introduction pipe 7 and the shower hole 8, and a predetermined amount is supplied. Keep at pressure. After that, high-frequency power is applied to the upper electrode 3 from the high-frequency power source 10 to generate plasma 14, and the wafer 1 is etched. Recently, there are many apparatuses provided with a high-frequency power supply 13 for applying a bias voltage to a lower electrode for the purpose of attracting ions due to the necessity of performing anisotropic etching.

As an etching gas, carbon tetrafluoride (C4F
8) When a mixed gas of argon (Ar) is used, a carbon compound composed of carbon, fluorine, hydrogen, etc. is applied to parts in the processing chamber, for example, insulating plate 4, susceptor 6, surface 2 of processing chamber wall 2, and the like. The polymer film 15 adheres. This is a so-called deposited film caused by a reaction product. Conventionally, the cause of film deposition on the processing chamber wall by etching is
It is said that such an etching gas and a product of the etching reaction are a polymer formed by being decomposed or combined in a plasma.

However, according to the results of the inventors of the present application analyzing the composition of deposits on the surface of the walls of various etching apparatuses and foreign substances adhering to the wafer, the cause of the film deposited in the processing chamber is the reaction. It is clear that there are many sputter-induced deposition films that adhere to other members to form a film when a certain member in the processing chamber is hit by a plasma and ion-sputtered, in addition to the product-induced deposition film. Was.

That is, for example, when the wall 2 of the processing chamber shown in FIG. 1 is made of an aluminum alloy and the surface 2 is anodized, the insulating plate 4, the susceptor 6, the cover 11 of the lower electrode, There are portions where a large amount of deposits having a composition of aluminum, oxygen and fluorine are detected, and there are also portions where the surface is rough and etched. Also, foreign substances detected from the wafer often include aluminum. That is, the cause of the formation of the deposited film on the inner wall of the processing chamber, which is a foreign matter generation source, is a deposited film caused by a reaction product due to an etching reaction and a deposited material caused by ion sputtering of members of the processing chamber.

According to the present invention, the cleaning process after the etching process includes a first process using plasma for removing a deposition film caused by a reaction product due to the etching process, and a process chamber in which the introduced gas is decomposed and polymerized by the plasma. It comprises a second step of forming a protective film against sputtering on the wall surface.
Therefore, first, the reaction product-derived deposited film is removed in the first step, and in the second step, a protective film for preventing the members in the processing chamber from being sputtered can be applied. That is, it is possible to prevent generation of a deposited film due to sputtering. That is, it is possible to remove the reaction product-derived deposited film and prevent the generation of the sputter-derived deposited film.

In this embodiment, specifically, cleaning with oxygen (O2) gas is used in the first step, and plasma of a mixed gas of carbon tetrafluoride (C4F8) and argon (Ar) is used in the second step. . In the second step, the flow rate ratio of C4F8 was set to be larger than that at the time of the etching treatment, and conditions for increasing the deposition property were set.

As shown in FIG. 2, on the wall surface 2 after the etching process, a reaction product-derived deposited film 15 made of a carbon compound is formed.
Adheres. Reference numeral 2 denotes a portion where the deposited film does not adhere and is under the etching condition. If the etching is continuously performed in this state, the sputter generated from 2 forms a sputter-induced deposited film 16 in another portion, and further reacts. The thickness of the product-derived deposited film 15 increases steadily. That is, both the reaction product-derived deposited film 15 and the sputter-derived deposited film 16 cause the generation of foreign matter 17.

Here, if the plasma cleaning of the present invention is performed, it is possible to suppress the generation of foreign matter by the reaction shown in FIG. That is, if plasma cleaning with O2 gas is performed as the first step after the etching process, the reaction product-derived deposited film (carbon compound) 15 deposited on the wall surface 2 by the etching reaction becomes carbon monoxide (CO) or carbon dioxide (CO2). CO2), and water (H2O)
Removed. Next, as a second step, if plasma is generated under a mixed gas condition of carbon tetrafluoride (C4F8) and argon (Ar) having increased deposition properties, a thin film 18 of a carbon compound is formed on the wall surface. Since the thin film 18 functions as a protective film for preventing the sputtering of the wall surface 2 at the time of the next etching process, the deposition of the sputtered material-deposited film 16 can be prevented. This protective film is basically composed of the same components as the reaction product-derived deposited film that adheres during the etching process, so that the reaction product-derived deposited film deposited during the etching process in the first step of the next cleaning process is performed. Removed with 15. Therefore, the deposited film 15 due to the reaction product, the deposited film 16 due to the sputter, the protective thin film 18 to be deposited in the second step of the cleaning process, and the deposited film thickness do not increase in the continuous processing step. It is possible to improve the effect and the effect of suppressing the generation of foreign matter.

As described above, the deposited film resulting from the decomposition and polymerization of the gas accompanying the etching process and the polymerization with the substance to be etched does not uniformly deposit in the processing chamber, and does not deposit depending on the etching conditions. Some parts, or parts that are etched back, appear. Therefore, when the present invention is carried out, the cleaning process interval, which determines how many etching processes are performed and then the cleaning process is performed in the continuous processing process for performing etching,
By providing a function that allows the etching apparatus to arbitrarily set how long the first step and the second step of the cleaning process are performed, more effective cleaning and foreign matter suppression can be performed. it can. If the same cleaning as the etching process with a high deposition property is performed in the etching processing with a small deposition property and a small etching reaction product, the deposition caused by sputtering is increased by hitting only the wall and returning. Corresponding to the conditions of the etching process,
It is desirable that the cleaning conditions be stored in each case, and that settings can be made to automatically perform the cleaning process according to the etching conditions.

The state of the deposited film in the processing chamber can be roughly classified into the following three states depending on the processing conditions of the wafer.

(1) The etching conditions are very strong in depositing properties, and a thick fluorocarbon film is deposited on the inner wall of the processing chamber.

(2) The etching condition is such that the deposition property is relatively light, a fluorocarbon-based film is deposited on a part of the inner wall of the processing chamber, and spatters in the processing chamber adhere to places.

(3) Deposition property is very light etching condition, and almost no fluorocarbon-based deposited film is found on the inner wall of the processing chamber, but sputters are deposited in some places in the processing chamber.

FIGS. 2 and 3 show the case (2). In addition, there are the case (1) shown in FIG. 4 and the case (3) shown in FIG.

In the case (1) shown in FIG. 4, since the reaction product-derived deposited film 15 adheres very thickly, the interval between the cleaning processes is made as short as possible, and the first step in the cleaning process is as follows. It is better to make it longer and the second step shorter. In extreme cases, the second step may be 0 seconds.

In case (3) shown in FIG. 5, the reaction product-derived deposited film 15 has very little adhesion and is liable to be sputtered on members in the processing chamber, so that the sputter-derived deposited film is mainly used. That is, during the etching process, there are many portions where the wall surface of the processing chamber is also under the etching conditions. Therefore, contrary to the case (1), the first step in the cleaning process is preferably shortened. In an extreme case, the first step may be 0 second. In this case, the thin film of the carbon compound formed on the surface of the inner wall of the etching chamber in the second step of the cleaning process serves as the protective film 18 for preventing the wall surface 2 from being sputtered during the etching process, and at the same time, the protective film. 18 is a sputtered substance 1 attached during the etching process.
There is also a suppressing effect of preventing the formation of foreign matter by embedding 7 in the protective film 18. In this case, performing the cleaning process before the start of the etching process is effective for preventing foreign matter.

That is, by performing the cleaning process before the start of the etching process, a thin film of the carbon compound is formed on the inner wall surface of the etching process chamber by the second step of the cleaning process before the start of the etching process. Spattering of the wall surface 2 at the time can be completely prevented. Even if the protective film is removed by the subsequent etching, the protective film 18 is regenerated by performing the cleaning process at appropriate intervals, so that the foreign substances can be more effectively suppressed.

A series of cleaning processes including the first process and the second process may be repeated a plurality of times while changing conditions such as time, flow rate, and pressure, as one means for improving the cleaning effect.

Although this embodiment has been described by taking a parallel plate type plasma etching apparatus as an example, a reactive ion etching apparatus for applying high frequency power to the lower electrode, an inductively coupled etching apparatus, a microwave etching apparatus, and the like. But the same is true. In addition to the etching apparatus, for example, the same effect can be obtained in a plasma CVD apparatus that periodically performs plasma cleaning.

[0035]

As described above, according to the present invention, it is possible to effectively remove the deposited film adhered to the inner wall of the etching chamber, which is a source of foreign matter. . As a result, it is possible to suppress the generation of dust due to an increase in the number of processed wafers, thereby improving the yield in the manufacturing process and improving the operation rate of the manufacturing apparatus.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a processing chamber of an etching apparatus according to an embodiment of the present invention.

FIG. 2 is a schematic view of the inner wall surface of the processing chamber of the etching apparatus according to the first embodiment of the present invention.

FIG. 3 is a schematic view of the inner wall surface of the processing chamber of the etching apparatus according to the first embodiment of the present invention.

FIG. 4 is a schematic view of a wall surface inside a processing chamber of an etching apparatus according to a second embodiment of the present invention.

FIG. 5 is a schematic view of a wall surface inside a processing chamber of an etching apparatus according to a third embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Semiconductor substrate, 2 ... Etching chamber, 2, 2 ...
Surface wall of processing chamber, 3 ... upper electrode, 4 ... insulating plate, 5
... lower electrode, 6 ... susceptor, 7 ... gas introduction pipe, 8 ... shower hole, 9 ... exhaust port, 10, 13 ... high frequency power supply, 11 ...
Lower electrode cover, 12: ground, 14: plasma, 1
5: Deposited film by etching reaction product, 16: Deposited by ion sputtering, 17: Foreign matter, 18: Protective film.

Continuing on the front page (72) Inventor: Takashi Takahashi 794, Higashi-Toyoi, Katsumatsu-shi, Yamaguchi Prefecture Inside the Kasado Plant of Hitachi, Ltd. (72) Inventor: Toshio Masuda 502, Kandachicho, Tsuchiura-shi, Ibaraki Pref. F term in the laboratory (reference) 4K057 DA20 DB05 DB20 DD01 DD03 DD08 DE06 DE08 DE14 DE20 DG07 DG08 DG12 DG13 DM02 DM04 DM05 DM06 DM14 DM17 DM29 DN01 5F004 AA13 AA15 BA04 BA09 BA20 BB11 BB18 BD07 CA09 DA00 DA01 DA23 DA26 DB03 DB03

Claims (5)

[Claims] A method for cleaning a plasma processing apparatus using plasma for removing a residue in a plasma processing apparatus chamber for processing a sample using plasma of a gas supplied into a processing chamber, wherein the cleaning processing is performed. A first step of using a plasma of a gas for removing etching reaction products, and a second step of decomposing a gas introduced by generating plasma to form a deposited film on a wall of the processing chamber. A cleaning method for a plasma processing apparatus, which is characterized by the following. 2. The plasma processing apparatus according to claim 1, wherein the plasma processing is etching using plasma of a fluorocarbon-based gas or a mixed gas containing a fluorocarbon-based gas. hand,
A cleaning method for a plasma processing apparatus, wherein a first step of a cleaning process comprises plasma of oxygen gas and a second step comprises plasma of a fluorocarbon-based gas or a mixed gas containing a fluorocarbon-based gas. . 3. A method for cleaning a plasma processing apparatus according to claim 1, wherein an arbitrary number of etching treatments is selected during the continuous processing of the substrate, and a cleaning treatment is performed for each of the number of etching treatments. Cleaning method for a plasma processing apparatus. 4. The cleaning method for a plasma processing apparatus according to claim 3, wherein the first step and the second step in the cleaning process are set and performed at an arbitrary time of 0 second or more. Cleaning method for a plasma processing apparatus. 5. The cleaning method for a plasma processing apparatus according to claim 1, wherein the cleaning process is performed before the start of the continuous substrate processing step.