JPH01242780A - Thin film-forming equipment and method for cleaning same - Google Patents

Abstract

PURPOSE:To remove deposits in a furnace by means of etching under optimum conditions by providing electrodes for producing plasma to the parts close to the connection of a reaction furnace with an exhaust system and removing the deposits in the furnace. CONSTITUTION:At the time of heating a substrate 1 in a reaction furnace and introducing a reactant gas to form a thin film, deposits 16, 15 are formed on the inner wall of the reaction furnace. In order to clean the inside of the reaction furnace, the inside of the reaction furnace is evacuated and the prescribed etching gas is introduced through a gas-introducing pipe 7. The introduced gas is formed into plasmic state in high-temp. and low-temp. regions by means of electrodes 8, 9, respectively, by which the deposits 16, 15 are gasified and removed. At this time, plasma may be independently produced respectively in high-temp. and low-temp. regions, and also activated etching gas may be used in the low-temp. region. By this method, the deposits in the furnace can be removed by means of etching under optimum conditions.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a thin film forming apparatus using chemical vapor deposition or the like and a cleaning method thereof.

(Prior Art) Chemical vapor deposition (CVD) is widely used mainly in the semiconductor industry. Particularly in the manufacturing process of integrated circuits, it is essential as one of the thin film forming methods. CVD methods include normal pressure CVD, which forms a film under atmospheric pressure, and reduced pressure CVD, which forms a film under reduced pressure. Generally, low pressure CVD is often used because of its excellent productivity and step coverage.

A film forming apparatus using the CVD method is usually constructed using a tubular container equipped with a vacuum evacuation function as a reaction furnace. The substrate on which a thin film is to be formed is loaded into the reactor, the vacuum is evacuated, the substrate is heated to a predetermined temperature by a resistance heater installed around the outer periphery of the reaction tube, and a reactive gas is introduced into the reactor. , film formation takes place. In such CVD equipment, the inner wall of the reactor is heated at the same time as the substrate is heated, but a rubber O-ring is usually used as a vacuum backing at the connection to the reactor exhaust system. Therefore, this part cannot be heated to a very high temperature. When heating the reactor above the backing's heat-resistant temperature of approximately 250°C, do not place a heater near the connection between the reactor and the exhaust system to keep this area at a lower temperature than the area where the substrate is heated. There is a need.

In such CVD equipment, depending on the reaction gas and film formation conditions, the gas may not be completely deposited on the substrate or the inner wall of the reactor in the high-temperature region of the reactor, and unnecessary deposits may be generated in the low-temperature region near the exhaust system. Sometimes. For example, when forming an arsenic-doped polycrystalline silicon film using silane (SiH+> gas and arsine (ASH3) gas), solid arsenic is deposited in the low temperature region.Organosilicon (e.g., Si(OC2H5)4)! :Organic arsenic (e.g. A
When forming an arsenic-doped glass film using a mixed gas of s (OC2Hs13), arsenic oxide is deposited in the low temperature region.

Deposits in the reactor of a CVD device have various adverse effects if left untreated. For example, the film becomes thick and peels off, becoming dust in the reactor, causing deterioration in the characteristics and yield of the film formed on the substrate. In addition, deposits in the low-temperature area near the exhaust system are
The cross-sectional area of the part near the exhaust system, which is already thin, is made smaller. This causes a pressure change during film formation, resulting in deterioration of uniformity of film formation, reduction in reproducibility, and the like. In cases such as the above example, the deposits in the low-temperature region are toxic substances and pose operational risks. For example, when removing a substrate on which a film has been formed, the vacuum is usually broken and the inside of the reactor is exposed to the atmosphere, but in this case there is a risk of evaporation of toxic deposits. Furthermore, when the reaction tube is cleaned for equipment maintenance, toxic substances are dissolved in the cleaning solution, which poses a problem in how to dispose of them.

Recently, as a cleaning method for easily removing deposits in a reactor, a method has been used in which an etching gas is introduced, turned into plasma, and reacted with the deposits. However, the purpose of the conventional method is to remove deposits in a high-temperature region heated by a heater, and as described above, there are problems when simply applying the method to remove deposits in a low-temperature region near the exhaust system.

That is, conditions suitable for removing thin film-like reactants deposited in the high-temperature region of the reactor are insufficient to remove large deposits in the low-temperature region. On the other hand, if conditions are set suitable for removing deposits in the low temperature region, overetching will occur in the high temperature region, causing pinholes and cracks in the quartz tube of the reactor.

(Problems to be Solved by the Invention) As described above, the conventional plasma cleaning method for CVD equipment is unable to effectively remove deposits in the high-temperature and low-temperature regions, where film deposition conditions are different. was there.

SUMMARY OF THE INVENTION An object of the present invention is to provide a thin film forming apparatus that solves these problems and can perform effective cleaning.

Another object of the present invention is to provide an effective method for cleaning a thin film forming apparatus.

[Structure of the Invention] (Means for Solving the Problems) The present invention provides, firstly, a thin film forming apparatus having a reactor equipped with a heater, a gas introduction system for forming a thin film, and an exhaust system. A plasma generating N pole for removing deposits in the furnace is provided near the connection with the exhaust system.

Second, the present invention provides a method for cleaning an all-forming equipment in which etching gas is introduced into a reactor and turned into plasma to remove deposits in the reactor.
It is characterized in that plasma is generated which is controlled independently in each of the low temperature regions near the connection between the high temperature region to be heated and the exhaust system.

Thirdly, the present invention provides a cleaning method for a thin film forming apparatus in which an etching gas is introduced into a reactor to remove deposits in the reactor. It is characterized in that it is decomposed and activated, and the activated gas is guided to a low-temperature region near the connection with the exhaust system to perform deposit etching in this low-temperature region.

(Function) According to the apparatus of the present invention, by focusing on the low-temperature region near the connection part with the exhaust system of the reactor and providing an electrode for plasma generation there, the low-temperature region can be controlled under different conditions from the high-temperature region. Deposits can be removed. For example, by providing separate electrodes for plasma generation in the low-temperature region and the high-temperature region,
If these are configured so that they can be controlled independently, the reactor can be cleaned according to regulations suitable for each area, depending on the substance and thickness of the deposit in each area.

Further, by using a method of generating plasma under independent conditions in the high-temperature region and the low-temperature region, thick deposits in the low-temperature region can be effectively removed without overetching or the like occurring in the high-temperature region.

Similarly, by thermally decomposing the etching gas in a high-temperature region and guiding it to a low-temperature region to etch the deposits there, it is possible to effectively remove thick deposits in the low-temperature region without over-etching in the high-temperature region. can be removed.

(Example) Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows a CVD\A arrangement according to an embodiment of the present invention. A quartz tube 1 and a resistance heating zone heater 2 provided around the quartz tube 1 constitute a reactor main body.

The quartz tube 1 is, for example, compatible with 8 inches (inner diameter 30 cm).At one end of the quartz tube 1, there is a door 12 for taking in and out substrates.
A reaction gas introduction pipe 3 for film formation is also provided. The other end of the quartz tube 1 is connected via a gate valve 4 to an exhaust system consisting of a mechanical booster pump 5, a rotary pump 6, and the like. The figure shows the boat 12 opened, and a large number of substrates 1 are loaded into the boat 13 and inserted into the reactor using a cantilever 14.

In this embodiment, in such a CVD apparatus, plasma generation electrodes 8 are separately controlled in a high temperature region heated by the heater 2 of the six furnaces and a low temperature region near the connection point with the exhaust system. .9 is provided. These electrodes8.
9 is controlled by a control circuit 10 including an RF main power source.

In addition to the reaction gas introduction pipe 3, the reactor is also provided with a gas introduction pipe 7 for introducing an etching gas for removing deposits in the reactor.

Thin film formation is carried out by inserting the substrate 1 into a reactor and evacuating it. An impurity gas is introduced to deposit a polycrystalline silicon film containing impurities.Alternatively, an oxygen gas is introduced simultaneously with a silicon compound gas to deposit a 1=silicon oxide film.

At this time, unnecessary deposits 16.15 are formed on the inner wall of the reactor. Usually, the deposit 16 in the high temperature region is a film-like reaction product of the same quality as the thin film to be formed on the substrate, and the deposit 15 in the low temperature region is a solidified product from unreacted gas, which is different from the thin film to be formed on the substrate. 1!Repeat the 10 formation steps to form a deposit 15.1
After the thickness reaches a certain level, the reactor is cleaned.

The cleaning process for this reactor is as follows. The interior of the reactor is evacuated and a predetermined etching gas is introduced from the gas introduction pipe 7.

In the high temperature region, the introduced gas is turned into plasma by the electrode 8,
It reacts with the deposit 16 to gasify and remove it. In the low temperature region, the etching gas is turned into plasma by the electrode 9 under conditions different from those in the high temperature region, and reacts with the deposit 15 to gasify and remove it.

These steps may be performed in any order or may be performed simultaneously. In short, deposits in the low temperature region and high temperature region 15.16
Taking into account the material and thickness of each material, the control circuit 10 may independently optimally set the plasma state for each material.

According to this embodiment, by plasma etching the deposits in the high-temperature region and the low-temperature region under independently controlled conditions, it is possible to completely clean the reactor without damaging it.

The second factor is another embodiment of the invention. Portions corresponding to those in FIG. 1 are given the same reference numerals as in FIG. M1, and detailed explanations are omitted. In the previous embodiment, the plasma generation electrodes 8 and 9 were fixedly provided in the high temperature region and the low temperature region of the reactor, respectively, whereas in this embodiment, the plasma generation electrode 17 in the high temperature region was fixedly provided in the high temperature region and the low temperature region. It is built into a quartz tube with a diameter smaller than the inner diameter of the reactor, and is inserted into the reactor only during cleaning. As a result, similar to the previous embodiment, high mm
The deposits 16 and 15 in the high temperature and low temperature regions are removed by plasma etching under independent conditions.

In this embodiment as well, the reactor can be effectively cleaned as in the previous embodiment.

FIG. 3 shows yet another embodiment. Portions corresponding to those in FIG. 1 are given the same reference numerals as in FIG. 1, and detailed description thereof will be omitted. In this embodiment, during cleaning, different etching conditions are provided in the high-temperature region and the low-temperature region by utilizing thermal decomposition instead of converting the etching gas into plasma. That is, in the reactor cleaning process, a predetermined etching gas is introduced into the reactor from the etching gas introduction pipe 7, and is heated by the heater 2 to thermally decompose it. By guiding the active gas generated by thermal decomposition to the low 1m area, the deposits 16 in the high temperature area and the deposits 15 in the low temperature area are removed.
can be etched under different etching conditions.

For example, arsenic glass (A
The case of forming a s S G ) film will be explained.

At this time, the deposit 16 in the high temperature region is mainly As5GI.
I! The deposit 15 in the low temperature region is arsenic oxide. In this case, for cleaning, nitrogen fluoride (NF3) is introduced as an etching gas, and it is heated with heater 2 to thermally decompose it, leading a large amount of fluorine radicals to a low temperature region, thereby removing arsenic oxide. Deposit 15 by reacting with
Remove by etching. Other fluorine-based gases such as hydrogen fluoride, sulfur fluoride, and carbon fluoride can be used as the etching gas, and chlorine-based gases such as carbon tetrachloride and sulfur hexachloride can also be used.

In this embodiment as well, since deposit etching can be performed under different conditions in the high temperature region and the low temperature region, the same effects as in the previous embodiments can be obtained.

The present invention is not limited to the above embodiments, and can be implemented with various modifications without departing from the spirit thereof.

[Effects of the Invention] As described above, according to the apparatus and method of the present invention, W
Deposits having different film quality and thickness in the high-temperature region and the low-temperature region in the JIll forming apparatus can be etched and removed under optimal conditions without damaging the reactor.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a CVD apparatus according to an embodiment of the present invention, and FIG.
The figure is a diagram for explaining another embodiment, and FIG. 3 is a diagram for explaining still another embodiment. DESCRIPTION OF SYMBOLS 1... Quartz tube, 2... Zone heater, 3... Reaction gas introduction pipe, 4... Gate valve, 5... Mechanical booster pump, 6... Rotary horn bulb, 7
... Etching gas introduction pipe, 8.9 ... Plasma generation electrode, 10 ... Control circuit, 11 ... Substrate, 1
2... Master, 13... Boat, 14... Cantilever, 15. j6... Sediment. Applicant's representative Patent attorney Suzue Takehiko Figure 3 Procedure Nei City Official Book (Method) 1938 to 7/7β Japan Patent Office Commissioner Furu 1) Moon Yi 1, Case Indication Patent Application No. 1983-70923 2 , Name of the invention Thin film forming device and its cleaning method 3, Relationship with the amended case Patent applicant (307) Toshiba Corporation 4, Agent Un Building 6, 3-7-2 Kasumigaseki, Chiyoda-ku, Tokyo; Full text of the specification subject to amendment 7, engraving of the specification originally attached to the request for amendment

Claims (3)

[Claims] (1) In a thin film forming apparatus having a reactor equipped with a heater, a gas introduction system for introducing a thin film forming gas into the reactor, and an exhaust system for exhausting the inside of the reactor, the A thin film forming apparatus characterized in that a plasma generating electrode for removing in-furnace deposits is provided in a portion near a connection with an exhaust system. (2) Introducing etching gas into a thin film forming apparatus that has a reactor equipped with a heater, a gas introduction system that introduces a thin film forming gas into the reactor, and an exhaust system that exhausts the inside of the reactor. In the method of removing internal deposits of the reactor by converting the reactor into plasma, a high temperature region heated by the heater of the reactor and a low temperature region near a connection with the exhaust system are each independently controlled. 1. A method for cleaning a thin film forming apparatus, characterized in that the method generates plasma. (3) Introducing etching gas into a thin film forming apparatus that has a reactor equipped with a heater, a gas introduction system that introduces a thin film forming gas into the reactor, and an exhaust system that exhausts the inside of the reactor. In the method for removing internal deposits from the reactor, the introduced etching gas is heated in the heater to thermally decompose and activate the etching gas, and the activated gas is transferred to a point near the connection with the exhaust system. 1. A method for cleaning a thin film forming apparatus, comprising introducing the reactor into a low temperature region and removing deposits within the reactor in the low temperature region.