WO1998001894A1

WO1998001894A1 - Method of manufacturing semiconductor integrated circuit device

Info

Publication number: WO1998001894A1
Application number: PCT/JP1996/001847
Authority: WO
Inventors: Hiroyo Nishiuchi; Toshiyuki Uchino; Masakazu Hoshino; Yuji Noguchi; Tadanori Yoshida; Akio Hoshino
Original assignee: Hitachi, Ltd.
Priority date: 1996-07-03
Filing date: 1996-07-03
Publication date: 1998-01-15

Abstract

In a method for manufacturing semiconductor integrated circuit devices, a technique for cleaning the inside of a treatment chamber by removing films deposited in the chamber by gas etching. Films deposited in the treatment chamber (2) and on the holding jig (3) of a low pressure CVD device at the time of forming films on the surface of a semiconductor wafer (4) are removed by supplying an etching gas to the chamber (2). During this dry cleaning, the temperature change in the chamber (20) is measured by means of a thermocouple (20) and the measured data are transmitted to a temperature change monitoring section (21). The section (21) decides the timing of the dry cleaning based on the temperature change in the chamber (2). As a result, the inside dry cleaning of the chamber (20) with an etching gas is accurately terminated without using any gas analyzer. After restarting CVD treatment, the films deposited in the chamber (2) and on the jig (3) do not separate from the chamber (2) and jig (3) and do not contaminate the wafer (4), because the films are dry cleaned to a prescribed thickness.

Description

Description Manufacturing method of semiconductor integrated circuit device Technical field

The present invention relates to a method for manufacturing a semiconductor integrated circuit device, and more particularly to a technique for cleaning a processing chamber by removing a deposited film deposited in the processing chamber by a gas etching in a film forming process. Background technology

2. Description of the Related Art A semiconductor integrated circuit device (hereinafter, referred to as an IC) is manufactured by forming a thin film on a semiconductor wafer (hereinafter, referred to as a wafer) and forming a circuit pattern on the thin film by a lithographic single-process etching process. . As a thin film forming method used in a thin film forming process for forming a thin film on a wafer, there is a method implemented using a reduced pressure CVD apparatus. When a thin film is formed on a wafer by the decompression CVD apparatus, the processing chamber is sealed after the wafer is carried into the processing chamber of the decompression CVD apparatus. The processing chamber is heated to about 500 to 900 by a heater, and is evacuated to about 10 Pa to 2 O O Pa by an evacuation device. A source gas required for film formation is supplied to the processing chamber where the processing conditions are maintained, and a thin film is formed on the wafer by a chemical reaction of the source gas caused by thermal energy.

By the way, when a film is formed by a chemical reaction of a source gas, a reaction product adheres not only on a wafer but also in a processing chamber or a jig. The reaction product accumulates in the processing chamber or jig each time the film forming method is repeatedly performed, and forms a film (hereinafter, referred to as a deposited film). Deposited film reaches a certain thickness When separated, it becomes dust and adheres to the wafer, which is a work, which causes product (IC) failure.

Therefore, conventionally, every time the deposited film reaches a certain thickness, the processing chamber or the jig is etched with a hydrofluoric acid aqueous solution to remove the deposited film deposited on the processing chamber or the jig. ing. However, this jet cleaning method requires immersion of the processing chamber and jig in a hydrofluoric acid aqueous solution, and also requires disassembly and reassembly of a low-pressure CVD apparatus, which increases the cleaning operation time, and reduces the pressure. The operating efficiency of the device will be reduced.

Therefore, as a cleaning method for preventing a decrease in the operating efficiency of the low-pressure CVD apparatus, a reactive etching gas (hereinafter referred to as an etching gas) such as chlorine trifluoride (C 1 F ₃ ) or hydrogen fluoride (HF) is used. The dry cleaning method used has been proposed The dry cleaning method is a method in which an etching gas is sent into a processing chamber and the deposited film is removed by etching with an etching gas. Since the work and the reassembly work can be omitted, the time required for the entire cleaning work can be shortened, and the operation efficiency of the low-pressure CVD apparatus can be prevented from being reduced.

An example describing a method of cleaning a thin film forming apparatus is disclosed in Japanese Patent Laid-Open Publication No. Heisei 7-919174. The cleaning method disclosed in this document is a method in which deposits are reacted and removed in a temperature range of 150 to 600 by using a mixed gas composition obtained by adding fluorine to nitrogen trifluoride.

Here, when the deposited film in the processing chamber or the jig of the low-pressure CVD apparatus is removed by the dry cleaning method, it is necessary to appropriately determine a point in time when the cleaning is completed. This is because the point at which cleaning ends is delayed. Otherwise, over-etching (excessive etching) due to the etching gas will damage the processing chamber and jig. Conversely, if the cleaning is terminated too early, the amount of etching by the etching gas will be insufficient, and the deposited film will not be sufficiently removed, resulting in production failure due to separation of the deposited film.

There are the following methods to determine exactly when to end cleaning. The first method is to equip the exhaust system of the decompression CVD device with a gas analyzer and detect the end point of cleaning by analyzing the components of the exhaust gas. The second method is a method in which the cleaning rate (etching rate) is empirically determined in advance based on experiments and past performance data, and the end point of the cleaning is managed over time.

However, the first method for detecting the end point of cleaning by the gas analyzer has the following problems. Gas analyzers are expensive and complex. If the analysis port of the gas analyzer becomes dirty, the sensitivity will drop and maintenance will be troublesome.

In the second method of managing the end point of the cleaning by time, the cleaning must be properly terminated when the cleaning conditions fluctuate due to fluctuations in the thickness of the deposited film and fluctuations in the flow rate of the etching gas. There is a problem that can not be.

An example that describes a method for accurately determining the time point at which dry cleaning is completed is described in Japanese Patent Application Laid-Open Publication No. HEI 5-97579. This document describes a technique that eliminates the need for expensive and complicated means for detecting the end point of etching such as a gas analyzer by calculating the thickness of the film deposited on the inner wall of the reaction chamber to be cleaned and determining the etching time. It has been disclosed.

An object of the present invention is to achieve dry cleaning without using a gas analyzer. It is intended to provide a method of manufacturing a semiconductor integrated circuit device which can be surely completed. Disclosure of the invention

According to the present invention, when the inside of a processing chamber is cleaned using an etching gas, a change in temperature of the processing chamber is directly or indirectly measured, and a point in time when cleaning is completed is determined based on the measurement data. It is characterized by doing.

Thus, dry cleaning inside the processing chamber by the etching gas can be accurately terminated without using the gas analyzer. BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a block diagram showing a reduced-pressure CVD apparatus used in a method of manufacturing IC, which is one embodiment of the present invention.

2A and 2B are a plan sectional view and a front sectional view, respectively. 3 (a) to 3 (e) are enlarged partial cross-sectional views showing main steps of an IC manufacturing method.

FIGS. 4 (a) and 4 (b) are graphs for explaining the action of determining the end point.

FIG. 5 is a block diagram showing a reduced pressure C VD apparatus used in the method of manufacturing IC according to the second embodiment of the present invention.

FIG. 6 is a block diagram showing a reduced-pressure CVD apparatus used in the method of manufacturing IC according to the third embodiment of the present invention.

FIG. 7 is a block diagram showing a reduced-pressure CVD apparatus used in the method of manufacturing IC according to the fourth embodiment of the present invention.

FIG. 8 shows the reduced pressure C used in the method of manufacturing an IC according to the fifth embodiment of the present invention. It is a block diagram showing a VD device.

FIG. 9 is a block diagram showing a batch type vertical decompression CVD apparatus used in a method of manufacturing IC according to Embodiment 6 of the present invention.

FIG. 10 is a block diagram showing a batch type horizontal decompression CVD apparatus used in a method of manufacturing IC according to Embodiment 6 of the present invention.

FIG. 11 is a block diagram showing a lamp heating type decompression CVD apparatus used in a method for producing IC which is Embodiment 7 of the present invention.

FIG. 12 is a professional and jig diagram showing a plasma CVD apparatus used in the method of manufacturing IC according to the eighth embodiment of the present invention.

FIG. 13 is a block diagram showing a dry etching apparatus used in the IC manufacturing method according to the ninth embodiment of the present invention.

FIG. 14 is a block diagram showing a dry mouth dry etching apparatus used in the method of manufacturing IC according to the tenth embodiment of the present invention. BEST MODE FOR CARRYING OUT THE INVENTION

The present invention will be described below with reference to the accompanying drawings in order to explain the present invention in more detail.

In the thin film forming step in the method for manufacturing a semiconductor integrated circuit device according to the present embodiment, a single-wafer decompression CVD device (hereinafter, simply referred to as a CVD device) shown in FIGS. 1 and 2 is used.

The CVD apparatus according to the present embodiment includes a process tube 1 made of quartz glass which is an example of a material having heat resistance and capable of preventing heavy metal contamination and the like. The process tube 1 is formed in a rectangular tube shape with both ends opened, and is placed horizontally so that the center line is horizontal. An inner chamber of the process tube 1 substantially forms a processing chamber 2, and a holding jig 3 is disposed inside the processing chamber 2. Holding jig 3 is the same as process tube 1. In this way, it is formed of quartz glass, and is configured to hold the wafer 4 horizontally.

An opening at one end of the process tube 1 substantially constitutes a furnace for loading and unloading a wafer as an object to be processed, and a furnace hole member 5 is connected to the furnace opening. A mouth lock chamber (not shown) is adjacently connected to the furnace member 5 of the process tube 1, and wafers are automatically loaded between the load lock chamber and the processing chamber 2 through the furnace member 5. It is designed to be carried out. A cap 6 is attached to the furnace member 5, and the cap 6 is configured to open and close the furnace member 5.

A plurality of gas supply ports 7 are formed in the upper side wall of the furnace member 5 so as to be arranged in the longitudinal direction, and a gas supply path 8 is connected to a group of the gas supply ports 7. The gas supply path 8 is surrounded by a source gas supply device 9. The source gas supply device 9 is configured to supply the source gas under the control of the film forming sequence controller 10. An etching gas supply device 11 is connected to the gas supply path 8 with a gun. The etching gas supply device 11 is controlled by an etching gas control unit 12 to supply an etching gas. I have.

The other end opening of the process tube 1 substantially constitutes a furnace end, and a furnace end member 13 is connected to the furnace end so as to close the opening. The furnace end member 13 is provided with a plurality of exhaust ports 14 arranged in the longitudinal direction, and an exhaust path 15 is connected to the group of the exhaust ports 14. The evacuation path 15 is connected to a vacuum evacuation device 1. The vacuum evacuation device 16 is controlled by a pressure control unit 17 so that the processing chamber 2 can be evacuated to a predetermined degree of vacuum. ing. The pressure controller 17 is connected to the film forming sequence controller 10.

Outside the process tube 1, a heater 18 for uniformly heating the inside of the processing chamber 2 throughout the process tube 1 surrounds the process tube 1. The facilities are as follows. The heater 18 is configured to be controlled by a temperature controller 19. The temperature controller 19 is configured to ensure control responsiveness and stability by PDI control.

A thermocouple 20 as a temperature sensor for detecting a cleaning end point is inserted inside the processing chamber 2 of the process tube 1, and the thermocouple 20 is connected to the temperature change monitoring unit 21. As shown in FIG. 2, the five thermocouples 20 are arranged on the bottom wall side of the processing chamber 2 so as to be as uniform as possible over the entire surface. In the following, when it is necessary to distinguish the five thermocouples 20, the one arranged on the furnace B side of the processing chamber 2 is the front thermocouple F, the one arranged in the center of the furnace is the central thermocouple C, The thermocouple placed on the furnace end side is called back thermocouple B, the thermocouple placed on the left side of the furnace center is called left thermocouple L, and the thermocouple placed on the right side of the furnace center is called right thermocouple R. The output terminal of the temperature change monitoring unit 21 is connected to one input terminal of the end point determination unit 22, and the other input terminal of the end point determination unit 22 has an end point table storing a table described later. Storage units 23 are connected. Further, the output end of the end point determination unit 22 is connected to the etching gas control unit 12, and the end point determination unit 22 transmits a determination result by an operation described later to the etching gas control unit 12. As shown in FIG. 2, the thermocouple 20 is housed inside the protective tube 24 and penetrated through the furnace end member 13 to be inserted into the processing chamber 2. The protection tube 24 is formed in an elongated tube shape with quartz glass, and one end protrudes from the furnace end member 13 to the outside. Since the thermocouple 20 is protected by the protection tube 24, temperature measurement under reduced pressure can be performed safely and accurately.

Next, a dry cleaning method for the CVD apparatus according to the above configuration is described in the field of the method for manufacturing a silicon (Si) gate nMOS transistor. For silicon oxide (S i 0 ₂₎ film forming step and the gate forming step will be described with reference to FIG.

As shown in FIG. 3 (a), in the field silicon oxide film formation process, first, an underlying silicon oxide film 32 for LOCOS is formed on a p-type silicon substrate (hereinafter, referred to as a substrate) 31. A silicon nitride (Si ₈ N ₄ ) film 33 is deposited. As described later, the silicon nitride film 83 is deposited using a CVD apparatus. Then, as shown in FIG. 3 (b), the silicon nitride film 33 is left in a portion where a transistor is to be formed later by photoetching, and boron (B) is ion-implanted using the photoresist film 34 as a mask. After that, wet oxidation using water vapor is performed, and as shown in FIG. 3 (c), the substrate 31 where there is no silicon nitride film 33 is oxidized to form a field oxide silicon film. 37 is formed. The boron implanted layer 35 forms a channel stop 36 that electrically separates adjacent elements.

Here, the CVD method of the silicon nitride film 33 by the CVD apparatus having the above configuration and the dry cleaning method following the CVD method will be described.

The wafer 4 as an object to be processed having the underlying silicon oxide film 32 formed on the substrate 31 is carried into the processing chamber 2 and placed on the holding jig 3 as shown in FIG. Is done. The inside of the processing chamber 2 is evacuated to a predetermined degree of vacuum (10 to 10 OPa) by the evacuation device 16. In addition, the inside of the processing chamber 2 is uniformly heated to a predetermined temperature (for example, about 400 * 0) by the heating 18.

Next, as a source gas for forming the silicon nitride film 33, for example, monosilane (SiH ₄ ) and ammonia (NH ₃ ) are supplied into the processing chamber 2 by the source gas supply device 9. . Raw material gas is supplied to processing chamber 2. It flows in from the supply port 7, flows downward while contacting the wafer 4 held by the holding jig 3, and is exhausted from the exhaust port 14. At this time, the source gas that comes into contact with the wafer 4 is in a state in which a chemical reaction has progressed due to thermal energy, and is thus deposited (deposited) on the wafer 4. Here, silicon nitride is deposited and the silicon nitride film 33 is deposited on the wafer 4 by the following reaction formula.

S i H ₄ + NH _S → S i ₃ N ₄ + H ₂

When a predetermined time has elapsed, the source gas supply device 9 stops supplying the source gas under the control of the film forming sequence control unit 10. The cap 6 is opened under the control of the film formation sequence controller 10, and the wafer 4 on which the silicon nitride film 33 is applied is picked up from the holding jig 3 by a handling device (not shown) and carried out of the processing chamber 2. Is done. Subsequently, the next wafer 4 is carried into the processing chamber 2 and held by the holding tool 3. Thereafter, the above operation is repeated.

By the way, when a film is formed by the reaction of the source gas, the reaction product adheres not only on the wafer 4 but also on the inner surface of the processing chamber 2 and the outer surface of the holding jig 3. The reaction product is deposited in the processing chamber 2 and the holding jig 3 each time the above-described operation of forming the silicon nitride film 33 by CVD is repeated to form a film (hereinafter, referred to as a deposited film). When the deposited film reaches a certain thickness, it separates into dust and adheres to the wafer 4 being processed, thereby causing a product defect. Therefore, in the present embodiment, when the deposited film reaches a certain thickness, the deposited film deposited on the processing chamber 2 and the holding jig 3 is removed by dry cleaning over the entire inside of the processing chamber 2. Is done. Hereinafter, the dry cleaning method will be described.

When the thickness of the silicon nitride deposited film (not shown) deposited on the inner surface of the processing chamber 2 or the outer surface of the holding jig 3 reaches a predetermined thickness, the film is formed. Switching from the film formation mode to the dry cleaning mode is performed by the can control unit 10. Here, the predetermined thickness is a value smaller than the thickness at which the deposited film is easily removed, and is determined in advance by empirical methods such as experiments, simulation tests using a computer, and analysis of past performance data. Is set. For example, the thickness is 1 m for a silicon nitride deposited film in a single-wafer CVD apparatus. Incidentally, the thickness of the deposited film can be obtained by multiplying the number of treatments by the deposition thickness per time. Further, the thickness of the deposited film may be measured by a film thickness measuring device.

When the mode is switched to the dry cleaning mode, loading of the wafer 4 into the processing chamber 2 is interrupted. The temperature of the processing chamber 2 is maintained by heating the heater 18 under the control of the temperature control unit 19 at the temperature during the film forming operation described above. Further, the pressure inside the processing chamber 2 is maintained by evacuation of the evacuation unit 16 under the control of the pressure control unit 17 by controlling the pressure during the film forming operation.

When the loading of the wafer 4 into the processing chamber 2 is interrupted, the etching gas is supplied from the etching gas supply device 11 into the processing chamber 2 through the gas supply path 8 under the control of the etching gas control unit 12. The etching gas flows into the processing chamber 2 from the gas supply port 7, flows downward while contacting the deposited film deposited on the inner surface of the processing chamber 2 and the outer surface of the holding jig 3, and is exhausted by the vacuum exhaust device 16. Exhausted from mouth 14. At this time, the etching gas that comes into contact with the deposited film is in a depressed state in which a chemical reaction has progressed due to thermal energy, so that the deposited film is etched. For example, when a fluorine (F ₂ ) gas is used as an etching gas, a silicon nitride deposited film is etched by the following reaction formula.

S i 8 N ₄ + 6 F ₂ → 3 S i F ₄ + 2 N ₂

The reaction product by the etching is exhausted from the exhaust port 14 by the vacuum exhaust device 16 together with the excess etching gas. Sediment 腠 is Etchin The inner surface of the processing chamber 2 and the outer surface of the holding jig 3 are relatively cleaned.

As described above, in the dry cleaning method using an etching gas, it is necessary to appropriately terminate the cleaning. In the present embodiment, the temperature change inside the processing chamber 2 during the dry cleaning is monitored by the temperature change monitoring unit 21 so that the end point of the cleaning is accurately determined.

First, when the etching of the deposited film by the etching gas starts, the internal temperature of the processing chamber 2 starts to rise due to the heat of the etching reaction. This temperature change is detected by the thermocouple 20 as shown in FIG. Fig. 4 is a graph showing the temperature change in the processing chamber during dry cleaning. The vertical axis shows the temperature difference CC), and the horizontal axis shows the elapsed time (in seconds) since the introduction of the etching gas. I have. In Fig. 4 (a), curve F is the temperature change detected by the front thermocouple F, curve C is the temperature change detected by the center thermocouple C, and curve B is the back thermocouple B The curve L shows the temperature change detected by the left thermocouple L, and the curve R shows the temperature change detected by the right thermocouple R.

In this embodiment, in which the internal temperature change of the processing chamber 2 is detected at a plurality of locations, the peak of each temperature change curve is monitored, and the arrival point of the last peak is determined as the end point by the end point determination unit 22. You. The reason for determining the last peak point as the end point of dry cleaning is that all the etching reactions caused inside the processing chamber 2 have reached their peaks, so that the dry cleaning is performed to a desired extent in all places in the processing chamber 2. This is because it can be estimated that it has been cleaned. By the way, the peak point of the temperature change can be detected in real time by monitoring the temperature change curve continuously from the temperature change monitoring unit 21. The temperature change song If 锒 is repeatedly inverted due to noise, etc., the temperature change monitoring unit

By comparing the actual data of 21 with the past actual data previously stored in the end point table storage unit 23 and correcting it, the peak point of the temperature change is determined by the data from the temperature change monitoring unit 21. It can be detected in real time.

For example, in FIG. 4A, the peak point in the curve R by the right thermocouple R is determined to be the end point. Note that the reason why the peaks of the curves R and L by the right thermocouple R and the left thermocouple L are later than the others is that the outer frame of the holding jig 3 is provided on the right wall surface and the left wall surface of the processing chamber 2 respectively. It is considered that the closer approach increases the size of the deposited film to be etched.

Here, if there is a variation in the distribution of the etching rate inside the processing chamber 2, a place where the cleaning is excessive ゃ a place where the cleaning is insufficient locally occurs in the processing chamber 2 to be dry-cleaned. For this reason, it is desirable to reduce the variation in the distribution of the etching rate inside the processing chamber 2 as much as possible. Variations in the distribution of the etching rate inside the processing chamber 2 should be reduced by increasing the flow rate of the etching gas inside the processing chamber 2 so that the consumption of the etching gas inside the processing chamber 2 becomes uniform. Can be. As a method of increasing the flow rate of the etching gas inside the processing chamber 2, there are a method of increasing the supply amount of the etching gas by the etching gas supply device 11 under the control of the etching gas control unit 12 and a method of exhausting by the vacuum exhaust device 16. There are ways to increase speed. If the distribution of the etching rate in the processing chamber 2 becomes uniform, the progress of the dry cleaning becomes uniform, so that the inner surface of the processing chamber 2 and the outer surface of the holding jig 3 are prevented from being damaged by over-etching, and the life is shortened. It can be extended, and the deposited film inside the processing chamber 2 is totally Cleaning can be performed uniformly.

By the way, in the conventional jet cleaning method for the CVD apparatus, since all the deposited film adhered to the inner surface of the processing chamber is removed, the deposited film is purposely formed on the inner surface of the processing chamber before the film forming process is restarted. (It is called empty devo.) If there is no deposited film on the inner surface of the processing chamber, the inside of the processing chamber is easily heated by the heater, which is different from the normal processing conditions where the deposited film adheres to the inner surface of the processing chamber. The desired film formation cannot be performed by the film formation sequence control designed based on the loose data and the like.

In the present embodiment, the dry cleaning is properly completed in a state where a thin deposited film remains on the inner surface of the processing chamber 2. By leaving the deposited film thinly on the inner surface of the processing chamber 2, it is not necessary to form the deposited film on the inner surface of the processing chamber 2 before restarting the processing, that is, the empty deposition step can be omitted. In addition, the downtime of the CVD apparatus can be reduced, and the operating efficiency of the CVD apparatus can be improved. Incidentally, the thickness of the deposited film left thinly on the inner surface of the processing chamber 2 is 40 nm to 90 nm.

As described above, when the arrival point of the last peak is determined as the end point by the end point determination unit 22, etching is in progress, and the deposited film remains thin on the inner surface of the processing chamber 2. In particular, when the distribution of the etching rate in the processing chamber 2 is controlled to be uniform, the deposited film can be thinly and uniformly left on the inner surface of the processing chamber 2.

The end point is not limited to be determined based on the arrival point of the last peak, but may be determined as follows.

(1) If there is only one temperature detection location, the end point is the point at which the temperature change peaks.

(2) The time when a predetermined period has elapsed since the peak of the temperature change End point. The predetermined period is obtained in advance by experiments or past execution data.

(8) The experiment and past data are stored as a table in the end point table storage unit 23, and the current temperature change data from the temperature change monitoring unit 21 is compared with the table, and the current temperature is compared. The point at which the value matches the temperature preset in the table is the end point.

(4) The temperature change is represented by a function of temperature and time, and as shown in Fig. 4 (b), the end point is point E when the slope changes when the temperature decreases. In other words, assuming that the temperature change is T and the elapsed time is t, the curve number of the temperature change is T = i (t). The point of satisfaction is the end point.

T '(t) <0

And T〃 (0 = 0

As described above, when the end point is determined by the end point determining unit 22 and a command to end the dry cleaning is issued to the etching gas control unit 12, the etching gas supply unit 11 is controlled by the etching gas control unit 12. The supply of the etching gas from is stopped. If necessary, a purge gas such as nitrogen gas is supplied from the etching gas supply device 11 or the source gas supply device 9 into the processing chamber 2. As a result, the etching reaction on the deposited film hardly occurs, and the dry cleaning is completed.

Thereafter, the CVD processing is restarted by the dry-cleaned CVD apparatus. In this case, as described above, the empty devouring step can be omitted. After the restart of the CVD process, the deposited film in the processing chamber 2 and the holding jig 3 of the CVD apparatus is dry-cleaned to a predetermined thickness, so that the deposited film does not separate from the processing chamber 2 and the holding jig 3. Is to be treated Does not contaminate the wafer 4.

In turn, the gate forming process will be described with reference to FIG.

After the silicon nitride film 33 used for LOCOS and the underlying silicon oxide film 32 are removed, as shown in FIG. 3 (d), a gate silicon oxide film 38 is newly formed by dry or hydrochloric acid (HC 1). It is formed by oxidation. Next, boron (B) is ion-implanted. Thereafter, a doped polysilicon film is deposited by the above-configured CVD apparatus, and a polysilicon gate 39 is formed by a photo-etching process and a dry * etching process as shown in FIG. 3 (e). You.

Here, a CVD method of the doped polysilicon film by the CVD apparatus having the above-described configuration and a dry cleaning method subsequent thereto will be described. The wafer 4 as the object to be processed into which the gate silicon oxide film 38 has been formed and the boron ions have been implanted is carried into the processing chamber 2 and placed on the holding jig 3 as shown in FIG. Is placed. The inside of the processing chamber 2 is evacuated to a predetermined degree of vacuum (10 to 10 OPa) by the vacuum exhaust device 16. And also, the processing chamber 2 by the heater 1 8 is uniformly heated throughout to a predetermined temperature (e.g., about 4 00 ^e C).

Next, as a source gas for forming a doped polysilicon film, for example, monosilane (SiH ₄ ) and phosphine (PH ₃ ) are supplied from the source gas supply device 9 into the processing chamber 2. The source gas flows into the processing chamber 2 from the gas supply port 7, flows downward while contacting the wafer 4 held by the holding jig 3, and is exhausted from the exhaust port 14. At this time, the source gas that comes into contact with the wafer 4 is in a state where the chemical reaction has progressed due to the thermal energy, so that the source gas is deposited (deposited) on the wafer 4. Here, a doped polysilicon film is deposited by the following reaction equation. _{_{S i H 4 + PH 8 -}} * S i + P + H 2

When a predetermined time has elapsed, the source gas supply device 9 stops supplying the source gas under the control of the film forming sequence control unit 10. The cap 6 is opened under the control of the film forming sequence control unit 10, and the wafer 4 coated with the doped polysilicon film is picked up from the holding jig 3 by a handling device (not shown) and unloaded from the processing chamber 2. Is done. Then, the next wafer 4 is carried into the processing chamber 2 and held by the holding jig 3. Thereafter, the above operation is repeated.

By the way, when a film is formed by the reaction of the source gas, the reaction product adheres not only on the wafer 4 but also on the inner surface of the processing chamber 2 and the outer surface of the holding jig 3. The reaction product is deposited in the processing chamber 2 and the holding jig 3 each time the above-described operation of forming the doped polysilicon film by CVD is repeated, thereby forming a film (hereinafter, referred to as a deposited film). When the thickness of the fertilizer film reaches a certain level, the fertilizer film separates and becomes dust and adheres to the wafer 4 being processed, thereby causing a product defect. Therefore, in the present embodiment, as in the case of the silicon nitride film described above, when the deposited film of doped silicon reaches a certain thickness, dry cleaning is performed over the entire interior of the processing chamber 2 to form the processing chamber. The deposited film deposited on 2 and the holding jig 3 is removed.

When the thickness of the doped polysilicon film deposited on the inner surface of the processing chamber 2 and the outer surface of the holding jig 3 reaches a predetermined value, the film forming sequence controller 10 controls the film forming mode. To dry cleaning mode. For example, in the case of a deposited film of doped polysilicon in a single-wafer CVD apparatus, the dry cleaning film thickness is as follows. When the mode is switched to the dry cleaning mode, the transfer of the wafer 4 into the processing chamber 2 is interrupted. The temperature of the processing chamber 2 is controlled by the temperature during the film forming operation described above. It is maintained by the heating of the heater 18 by the control of 19. Further, the pressure inside the processing chamber 2 is maintained by evacuation of the evacuation unit 16 under the control of the pressure control unit 17 by controlling the pressure during the film forming operation.

When the transfer of the wafer 4 into the processing chamber 2 is interrupted, the etching gas is supplied from the etching gas supply device 11 into the processing chamber 2 through the gas supply path 8 under the control of the etching gas control unit 12. The etching gas flows into the processing chamber 2 from the gas supply port 7, flows downward while contacting the deposited film deposited on the inner surface of the processing chamber 2 and the outer surface of the holding jig 3, and is exhausted by the vacuum exhaust device 16. Exhausted from mouth 14. At this time, the etching gas that comes into contact with the deposited film is in a state in which the chemical reaction has progressed due to thermal energy, so that the deposited film is etched. For example, when chlorine trifluoride (C 1 F _s ) gas is used as an etching gas, a deposited film of doped polysilicon is etched by the following reaction formula.

2S i +4 C 1 F ₃ → S i F ₄ + S i C 1 ₄ +2 F ₂ + C "

_{_{2P 2 0 6 + 2C l F}} 3 → 2PF 3 + 50 2 + C 1 2

Note that in the formula, 0 is oxygen in the gate silicon oxide film.

The reaction product from the etching is exhausted from the exhaust port 14 by the vacuum exhaust device 16 together with the excess etching gas. The deposited film is gradually removed by etching, and the inner surface of the processing chamber 2 and the outer surface of the holding jig 3 are relatively cleaned.

As described above, by monitoring the temperature change inside the processing chamber 2 during the dry cleaning by the temperature change monitoring unit 21, the end point of the cleaning is accurately determined. In the present embodiment in which a change in the internal temperature of the processing chamber 2 is detected at a plurality of locations, the peak of each temperature change curve is monitored, and the arrival point of the last peak is determined as the end point by the end point determination unit 22. In the present embodiment, the dry cleaning can be accurately completed by the state where the entrapment film remains thin on the inner surface of the processing chamber 2. By leaving the deposited film thinly on the inner surface of the processing chamber 2, it is not necessary to form the fertilizer on the inner surface of the processing chamber 2 before the processing is restarted, that is, the empty devouring process can be omitted. Therefore, the downtime of the CVD apparatus can be reduced, and the operating efficiency of the CVD apparatus can be improved. Incidentally, the thickness of the deposited film left thinly on the inner surface of the processing chamber 2 is 40 nm to 90 nm.

As described above, the end point is determined by the end point determination unit 22, and when an instruction to terminate the dry cleaning is issued to the etching gas control unit 12, the etching gas supply unit is controlled by the etching gas control unit 12. The supply of the etching gas from the device 11 is stopped. If necessary, a purge gas such as a nitrogen gas is supplied from the etching gas supply device 11 or the raw material gas supply device 9 into the processing chamber 2. As a result, the etching reaction on the deposited film is almost eliminated, and the dry cleaning is completed.

Thereafter, the CVD film forming process is restarted by the dry-cleaned CVD apparatus. At this time, as described above, the empty deposition step can be omitted. After the restart of the CVD film forming process, the deposited film in the processing chamber 2 and the holding jig 8 of the CVD apparatus is dry-cleaned to a predetermined thickness, so that the deposited film does not fall off, and the deposited film is a wafer as an object to be processed. No contamination of 4

As described above, according to the present invention, the following effects can be obtained.

(1) When the deposited film deposited inside the processing chamber is dry-cleaned by the etching gas, the dry cleaning can be properly terminated, thereby preventing excessive and insufficient dry cleaning. be able to. (2) By preventing excessive dry cleaning, the processing chamber and the holding jig can be prevented from being damaged by over-etching, so that the life of the processing chamber and the holding jig can be extended.

(3) By preventing shortage of dry cleaning, it is possible to prevent the deposited film from falling off, so that the quality of processing can be improved, and the quality and reliability of processed products can be improved.

(4) By detecting the temperature change during dry cleaning with a thermocouple, the dry cleaning can be properly terminated, eliminating the need for expensive and complicated measuring instruments such as gas analyzers. The cost of the entire processing apparatus can be reduced.

(5) By properly terminating the dry cleaning with a thin deposited film remaining, the empty deposition step can be omitted, thereby reducing the downtime of the processing equipment and improving the operating efficiency of the processing equipment. Can be improved.

FIG. 5 shows the reduced pressure C used in the method of manufacturing IC which is Embodiment 2 of the present invention.

It is a block diagram which shows a VD apparatus.

The second embodiment is different from the first embodiment in that a thermocouple 20 for monitoring a temperature change during dry cleaning is provided outside the processing chamber 2 and in the vicinity of the processing chamber 2. Is a point. Also in the second embodiment, the thermocouples 20 are arranged such that a plurality of thermocouples are as uniform as possible on one plane. According to the second embodiment, since the thermocouple 20 is disposed outside the processing chamber 2, the protection tube 24 can be omitted.

FIG. 6 shows the reduced pressure C used in the method of manufacturing IC which is Embodiment 3 of the present invention.

It is a block diagram showing a VD device.

The third embodiment differs from the first embodiment in that a thermocouple 20 for monitoring a temperature change during dry cleaning is installed inside the heater 18. That is the point. Also in this embodiment, the thermocouples 20 are arranged such that a plurality of thermocouples 20 are equally distributed on a plane. According to the third embodiment, since the thermocouple 20 is disposed outside the processing chamber 2, the protective tube 24 can be omitted. In addition, since the heat couple 20 is provided inside the heater 18, it can be used for monitoring the heating temperature of the heater 18 during the film forming process. In other words, the thermocouple 20 can also serve as a thermocouple for monitoring the heating temperature of the heater 18.

FIG. 7 is a block diagram showing a reduced-pressure CVD apparatus used in the method for producing IC according to the fourth embodiment of the present invention.

Embodiment 4 is different from Embodiment 1 in that a power supply amount of a temperature control unit 19 for controlling a heater 18 is controlled by a temperature instead of a thermocouple for monitoring a temperature change during dry cleaning. The change monitoring unit 21 is configured to monitor a temperature change during dry cleaning. The temperature controller 19 controls the power of the heater 18 so that the internal temperature of the processing chamber 2 is always constant. During dry cleaning, heat of reaction that is not generated during the film forming process is generated inside the processing chamber 2 due to a chemical reaction between the etching gas and the fertilizer film. As a result, the temperature of the processing chamber 2 tends to increase during dry cleaning, and the temperature control unit 19 suppresses the temperature increase of the processing chamber 2 by reducing the amount of power supplied to the heater 18. I do. Therefore, by monitoring the power supply amount of the temperature control unit 19 by the temperature change monitoring unit 21, it is possible to indirectly monitor the temperature change of the processing chamber 2 during the dry cleaning. According to the fourth embodiment, a thermocouple for detecting a temperature change during dry etching can be omitted.

FIG. 8 is a block diagram showing a decompression CVD apparatus used in the method for manufacturing an IC according to the fifth embodiment of the present invention. The fifth embodiment differs from the first embodiment in that a thermocouple 20 for monitoring a temperature change during dry cleaning is provided inside the exhaust passage 15. Also in the fifth embodiment, it is desirable to arrange a plurality of thermal couples 20. By measuring the temperature of the exhaust gas at one or more points, the heat of reaction between the etching gas and the deposited film can be measured, so that the end point of the dry cleaning can be accurately detected. According to the fifth embodiment, since the thermocouple 20 is disposed outside the processing chamber 2, the protection tube 24 can be omitted.

The fifth embodiment differs from the first embodiment in that a batch type vertical decompression CVD device is used. The process tube 1A of the batch type vertical decompression CVD device is a large-diameter cylindrical tube 1a with one end closed and the other end open, and a small-diameter cylindrical inner tube 1 with both ends open. b, the inner tube 1a and the inner tube 1b are installed vertically with the closed side of the outer tube 1a facing upward, with the inner tube 1a and the inner tube 1b being arranged concentrically with each other. . A holding jig 3A is coaxially arranged inside the inner tube 1b. The holding jig 3A is configured to hold 100 to 180 wafers 4 in parallel with each other with their centers substantially aligned. The holding jig 3A is carried into the inner tube 1b while being placed on a cabinet 6A provided to be able to advance and retreat at the opening of the inner tube 1b.

A gas supply port 7 is provided at the lower end of the inner tube 1b, and a gas supply path 8 is connected to the gas supply port 7 through the outer tube la. A source gas supply device 9 is connected to the gas supply path 8, and the source gas supply device 9 is controlled by a film formation sequence controller 10 to control the source gas. And is configured to supply An etching gas supply device 11 is connected to the gas supply path 8, and the etching gas supply device 11 is controlled by an etching gas control unit 12 to supply an etching gas. I have.

An exhaust port 14 is opened at the lower end of the tube wall of the outer tube 1a, and an exhaust path 15 is connected to the exhaust port 14. A vacuum exhaust device 16 is connected to the exhaust path 15, and the vacuum exhaust device 16 can evacuate the processing chamber 2 of the process tube 1 A to a predetermined degree of vacuum by the pressure controller 17. It is configured as follows. The pressure controller 17 is connected to the film forming sequence controller 10. Outside the process tube 1A, a heater 18 for uniformly heating the inside of the processing chamber 2 throughout is provided so as to surround the process tube 1A. The heater 18 is configured to be controlled by a temperature controller 19. The temperature controller 19 is a PDI system and is configured to ensure control responsiveness and stability. Inside the processing chamber 2 of the process tube 1A, a thermocouple 20 as a temperature sensor for detecting the end point of cleaning is provided. The thermocouple is inserted between the inner tube 1 a and the inner tube 1 b while being housed in the protective tube 24, and the thermocouple 20 is connected to the temperature change viewing unit 21. The plurality of thermal couples 20 are arranged so as to be as evenly distributed as possible in the outer peripheral portion of the processing room 2. The output terminal of the temperature change monitoring unit 21 is connected to one input terminal of the end point determination unit 22, and the other input terminal of the end point determination unit 22 is connected to the end point table storage unit 28. ing. The output end of the end point determination unit 22 is connected to the etching gas control unit 12, and the end point determination unit 22 transmits the determination result to the etching gas control unit 12.

Batch type vertical low pressure CVD equipment is also formed by the reaction of raw material gas. When the film is formed, reaction products are deposited on the inner surface of the processing chamber 2 and the outer surface of the holding jig 3 to form a film. When the deposited film reaches a certain thickness, it separates and contaminates the wafer 4 being processed, so cleaning is necessary even in a batch type vertical low pressure CVD apparatus. Next, a dry cleaning method of a batch type vertical low pressure CVD apparatus will be described.

When the deposited film deposited on the inner surface of the processing chamber 2 or the outer surface of the holding jig 3 reaches a predetermined thickness, the film forming sequence controller 10 switches from the film forming mode to the dry cleaning mode. Here, the predetermined thickness of the deposited film for which dry cleaning is to be started in a batch type low-pressure CVD apparatus is, for example, 1; / m for a deposited film of silicon nitride, and 3 for a doped polysilicon. ju m.

When the mode is switched to the dry cleaning mode, the loading of the wafer 4 into the processing chamber 2 is interrupted, and the holding jig 3A is loaded into the processing chamber 2 in a state in which the wafer 4 group is not held. The temperature of the processing chamber 2 is maintained by heating the heater 18 under the control of the temperature control unit 19 at the time of the film forming operation. Further, the pressure inside the processing chamber 2 is maintained by evacuation of the evacuation unit 16 under the control of the pressure control unit 17 by controlling the pressure during the film forming operation. Next, the etching gas is supplied from the etching gas supply device 11 into the processing chamber 2 through the gas supply path 8 under the control of the etching gas control unit 12. The etching gas flows into the processing chamber 2 from the gas supply port 7, flows while contacting the deposited film deposited on the inner surface of the processing chamber 2 and the outer surface of the holding jig 3 A, and is exhausted by the vacuum exhaust device 16. Exhausted from 4. At this time, the etching gas in contact with the deposited film is in a state where a chemical reaction has progressed due to thermal energy, so that the deposited film is etched. The reaction product by the etching is exhausted from the exhaust port 14 by the vacuum exhaust device 16 together with the excess etching gas. The deposited film is gradually removed by etching. However, the inner surface of the processing chamber 2 and the outer surface of the holding jig 3A are relatively cleaned.

When the etching of the deposited film by the etching gas starts, the internal temperature of the processing chamber 2 starts to rise due to the heat of the etching reaction. In the present embodiment in which a change in the internal temperature of the processing chamber 2 is detected at a plurality of locations, the peak of each temperature change curve is monitored, and the point of arrival of the last peak is determined by the end point determination unit 22 as the end point. When the arrival point of the last peak is determined as the end point by the end point determination unit 22, the etching is in progress, and the deposited film remains thin on the inner surface of the processing chamber 2. If the distribution of the etching rate inside the processing chamber 2 is controlled to be uniform, the deposited film can be thinly and uniformly left on the inner surface of the processing chamber 2.

Therefore, dry cleaning is properly terminated with a thin deposited film remaining on the inner surface of the processing chamber 2. By leaving the deposited film on the inner surface of the processing chamber 2, it is not necessary to form the deposited film on the inner surface of the processing chamber 2 before resuming the processing. The downtime of the vertical CVD system can be reduced, and the operating efficiency of the vertical CVD system can be improved. Incidentally, the thickness of the deposited film left thin on the surface of the processing chamber 2 is 40 nm to 90 nm.

Note that the end point is not limited to be determined based on the arrival point of the last peak, but can be appropriately determined according to conditions, as in the first embodiment.

£ (When the end point is determined by the end point determination unit 22 as described above and a command to end the dry cleaning is issued to the etching gas control unit 12, the etching gas supply unit is controlled by the etching gas control unit 12. The supply of the etching gas from the device 11 is stopped, and a purge gas such as a nitrogen gas is supplied from the etching gas supply device 11 or the source gas supply device 9 into the processing chamber 2 as necessary. To the deposited film Since the etching reaction hardly occurs, the dry cleaning is completed.

Thereafter, the CVD film formation process is restarted by the dry vertical vacuum type CVD apparatus that has been cleaned. At this time, as described above, the empty devouring step can be omitted. After the restart of the CVD process, the deposited film in the processing chamber 2 and the holding jig 3 of the batch type vertical decompression CVD apparatus is dry-cleaned to a predetermined thickness, and thus is separated from the processing chamber 2 and the holding jig 3. The deposited film does not contaminate the wafer 4 to be processed 0

Embodiment 6 is different from Embodiment 1 in that a batch type horizontal decompression CVD apparatus is used. The configuration and operation of the batch type horizontal depressurized CVD apparatus are the same as those of the batch type vertical depressurized CVD apparatus except that the process tube 1B is placed horizontally, and therefore the description thereof is omitted.

The seventh embodiment differs from the first embodiment in that a ramp-heating type reduced pressure CVD apparatus is used. The lamp heating type decompression CVD device 40 has a base 41 formed in a disk shape, and the upper cup 42 and the lower cup 43 formed of quartz glass are processed above and below the base 41. Chambers 4 are arranged to form 4. In the processing chamber 44, a susceptor 45 as a holding jig for holding the wafer 4 is concentrically arranged in the same plane as the base 41. The susceptor 45 is supported by a support shaft 46. The support shaft 46 is moved up and down by a vertical movement device (not shown) and rotated by a rotation drive device (not shown). I have. A part of the lower cup 43 has an opening 47 for taking in and out a wafer as an object to be processed. The loading / unloading chamber (not shown) is adjacently connected to the loading / unloading port 47, and the wafer is transferred between the load lock chamber and the processing chamber 4 through the loading / unloading port 47 through a handling device (not shown). ) Is automatically loaded and unloaded one by one. 0 A cap 48 is attached to the entrance 47, and the cap 48 is configured to open and close the entrance 47. .

Outside the upper cup 42 and the lower cup 43, a plurality of heating lamps 18A for uniformly heating the entire inside of the processing chamber 44 are provided. The heating lamp 18 A is configured to be controlled by the temperature control unit 19.

The base 41 has a gas supply unit 7, and the gas supply unit 7 is connected to a gas supply line 8. A source gas supply device 9 is connected to the gas supply path 8, and the source gas supply device 9 is configured to supply a source gas under the control of a film formation sequence control unit 10. An etching gas supply device 11 is connected to the gas supply path 8 by a gun, and the etching gas supply device 11 is controlled by an etching gas control unit 12 to supply an etching gas. The base 41 has an exhaust port 14, and the exhaust port 14 is connected to an exhaust path 15. A vacuum exhaust device 16 is connected to the exhaust path 15, and the vacuum exhaust device gl 6 is controlled by the pressure control unit 17 so as to be able to evacuate the processing chamber 44 to a predetermined degree of vacuum. ing. The pressure control section 17 is connected to the film formation sequence control section 10.

A plurality of thermocouples 20 as temperature sensors for detecting the end point of cleaning are arranged outside the upper cup 42 and the lower cup 43, respectively, and are disposed in close proximity to the processing chamber 44, and the thermocouple 20 monitors a temperature change. Connected to part 21. The thermocouple 20 is arranged so that the temperature distribution of the processing chamber 44 can be measured over the whole. In addition, a plurality of radiation thermometers 2 OA as temperature sensors for detecting a cleaning end point are provided outside the upper cup 42 and the lower cup 43, and the temperature of the susceptor 45 and the base 41 in the processing room 44 is measured. It is equipped to perform non-contact measurement, and a radiation thermometer 2 OA is also connected to the temperature change monitoring unit 21. The radiation thermometer 2OA is also arranged so that the temperature distribution in the processing chamber 44 can be measured throughout. The output terminal of the temperature change monitoring unit 21 is connected to one input terminal of the end point determination unit 22, and the other input terminal of the end point determination unit 22 is connected to the end point table storage unit 23. . Further, the output end of the end point determination unit 22 is connected to the etching gas control unit 12, and the end point determination unit 22 sends the determination result to the etching gas control unit 12.

Even in a lamp-heated decompression CVD apparatus, when a film is formed by the reaction of a source gas, reaction products are deposited on the inner surface of the processing chamber or the outer surface of a susceptor as a holding jig to form a film. When the deposited film reaches a certain thickness, it condenses and contaminates the wafer being processed, so cleaning is necessary even in a lamp heating type decompression CVD device. Next, a dry cleaning method for a lamp heating type decompression CVD apparatus will be described.

When the thickness of the deposited film deposited in the processing chamber 44 or the susceptor 45 reaches a predetermined thickness, the film forming sequence controller 10 switches from the film forming mode to the dry cleaning mode. Here, in a lamp heating type decompression CVD apparatus which is an example of a single wafer type decompression CVD apparatus, a predetermined thickness of a deposited film to start dry cleaning is, for example, 1 m for a deposited film of silicon nitride. In the case of doped polysilicon, the length is 3 m.

When the mode is switched to the dry cleaning mode, the processing chamber 4 C The loading of 4 is suspended. The temperature of the processing chamber 44 is maintained by heating the heating lamp 18 A under the control of the temperature control unit 19 while controlling the temperature during the growth operation. The pressure inside the processing chamber 44 is maintained by evacuation of the evacuation unit 16 under the control of the pressure control unit 17 by controlling the pressure during the growth operation. Next, an etching gas is supplied from the etching gas supply device 11 into the processing chamber 2 through the gas supply path 8 under the control of the etching gas control unit 12. The etching gas flows into the processing chamber 2 from the gas supply unit 7, flows while contacting the deposited film deposited on the processing chamber 2 and the sasse pig 45, and is exhausted from the exhaust port 14 by the vacuum exhaust device 16. Is done. At this time, since the etching gas in contact with the deposited film has undergone a chemical reaction due to thermal energy, the deposited film is etched. The reaction product from the etching is exhausted from the exhaust port 14 by the vacuum exhaust device 16 together with the excess etching gas. The deposited film is gradually removed by etching, and the processing chamber 2 and the susceptor 45 are gradually cleaned relatively.

When the etching of the deposited film by the etching gas starts, the internal temperature of the processing chamber 44 starts to rise due to the heat of the etching reaction. In the present embodiment in which the temperature change inside the processing chamber 44 is detected at a plurality of locations, the peak of each temperature change curve is monitored, and the point of arrival of the last peak is determined as the end point by the end point determination unit 22. You. If the end point of the final peak is determined by the end point determination unit 22 as the end point, etching is in progress, and the deposited film remains thin on the inner surface of the processing chamber 44. In particular, when the distribution of the etching rate in the processing chamber 44 is controlled to be uniform, the deposited film can be thinly and uniformly left on the inner surface of the processing chamber 44.

Therefore, dry cleaning is properly terminated with a thin deposited film remaining on the inner surface of the processing chamber 44. Processing chamber 4 Leave thin deposited film on inner surface of 4 As a result, it is not necessary to form a deposited film on the inner surface of the processing chamber 44 before the processing is resumed, that is, since the empty deposition step can be omitted, the downtime of the ramp-heating type decompression CVD apparatus can be reduced. The operation efficiency of the lamp heating type decompression CVD apparatus can be improved. Incidentally, the thickness of the deposited film left thinly on the inner surface of the processing chamber 44 is 40 nm to 90 nm.

Note that the end point is not limited to be determined based on the arrival point of the last peak, but can be appropriately determined according to conditions, as in the first embodiment. As described above, the end point is determined by the end point determination unit 22, and when a command to end the dry cleaning is issued to the etching gas control unit 12, the etching gas supply unit 1 is controlled by the etching gas control unit 12. The supply of the etching gas from 1 is stopped. If necessary, a purge gas such as a nitrogen gas is supplied from the etching gas supply device 11 or the source gas supply device 9 into the processing chamber 44. As a result, the etching reaction on the deposited film hardly occurs, and the dry cleaning is completed.

Thereafter, the CVD film forming process is restarted by the dry-heated, low-pressure, lamp-heated CVD apparatus. At this time, as described above, the empty devouring step can be omitted. After the restart of the CVD process, the deposited film in the processing chamber 44 and the susceptor 45 of the lamp heating type decompression CVD apparatus is dry-cleaned to a predetermined thickness. The deposited film does not contaminate the wafer 4 to be processed.

FIG. 12 is a block diagram showing a plasma CVD apparatus used in the IC manufacturing method according to the eighth embodiment of the present invention.

Embodiment 8 is different from Embodiment 1 in that the plasma CVD apparatus It is the point used. The plasma CVD apparatus 50 includes a base 51 formed in a disk shape. On the base 51, an upper cup 52 and a lower cup 53 formed in a large and small diameter cylindrical shape are disposed in a processing chamber 54. Are arranged to form Inside the processing chamber 54, a lower electrode 55 also serving as a susceptor as a holding jig for holding the wafer 4 is arranged concentrically in the same plane as the base 51. Is configured to generate plasma with the upper electrode 59 disposed facing upward. The lower electrode 55 is supported by a support shaft 56, and the support shaft 56 is moved up and down by a vertical movement device (not shown) and rotated by a rotary drive device (not shown). Has become. A part of the upper cup 52 and a part of the lower cup 53 is provided with an inlet / outlet 57 for taking in / out a wafer as an object to be processed. A load lock chamber (not shown) is instantaneously connected to the loading / unloading port 57, and the wafer passes through the loading / unloading port 57 between the load α chamber and the processing chamber 5, and a handling device (not shown). ) Automatically loads and unloads one by one. A cabinet 58 is attached to the entrance 57, and the cabinet 58 is configured to open and close the entrance 57.

A quartz glass window 60 is fitted in the center of the base 51, and a heating lamp 18 mm for uniformly heating the entire inside of the processing chamber 54 is provided below the quartz glass window 60. Multiple units are installed. The heating lamp 18 A is configured to be controlled by the temperature controller 19. A gas supply port 7 is opened in the upper cup 52 so as to face the upper electrode 59, and a gas supply path 8 is connected to the gas supply port 7. A source gas supply device 9 is connected to the gas supply path 8, and the source gas supply device g9 is configured to supply a source gas under the control of a film formation sequence control unit 10. In addition, an etching gas supply device is An etching gas supply device 11 is controlled by an etching gas control unit 12 to supply an etching gas. An exhaust port 14 is opened in the upper cup 52, and an exhaust path 15 is connected to the exhaust port 14. A vacuum exhaust device 16 is connected to the exhaust path 15, and the vacuum exhaust device 16 is controlled by a pressure control unit 17 so that the processing chamber 54 can be evacuated to a predetermined degree of vacuum. It has been done. The pressure controller 17 is in contact with the film forming sequence controller 10. A plurality of thermocouples 20 as temperature sensors for detecting the end point of cleaning are arranged outside the upper cup 52 and the lower cup 53 in close proximity to the processing chamber 54, and the thermocouple 20 monitors a temperature change. Connected to part 21. The thermocouple 20 is arranged so that the temperature distribution of the processing chamber 54 can be measured throughout. A plurality of radiation thermometers 2 OA as temperature sensors for detecting a cleaning end point are provided outside the upper cup 52 and the lower cup 53. The thermometer 2 OA is also connected to the temperature change monitoring unit 21. The radiation thermometer 2OA is also arranged so that the temperature distribution in the processing chamber 54 can be measured throughout. The output terminal of the temperature change monitoring unit 21 is connected to one input terminal of the end point judgment unit 22.The other input terminal of the end point judgment unit 22 is connected to the end point table storage unit 23. I have. Further, the output terminal of the end point determination unit 22 is connected to the etching gas control unit 12, and the end point determination unit 22 transmits the determination result to the etching gas control unit 12.

Also in the plasma CVD apparatus, when the reaction gas is formed by the reaction of the raw material gas, a reaction product is deposited on an inner surface of the processing chamber or an outer surface of the substrate as a holding jig to form a film. When the deposited film reaches a certain thickness, it becomes contaminated and contaminates the wafer being processed. Is necessary.

Except that the etching gas is activated by the plasma, the operation is substantially the same as that of the above-described lumped heating type decompression CVD apparatus, so that the description of the dry cleaning method of the plasma CVD apparatus is omitted.

FIG. 13 is a block diagram showing a dry etching apparatus used in the method of manufacturing IC, which is Embodiment 9 of the present invention.

Embodiment 9 is different from Embodiment 1 in that a dry etching apparatus is used. The dry etching apparatus 61 has a disk-shaped base 62, and a hemispherical dome-shaped cover 63 is formed on the base 62 in cooperation with the base 62. 6 4 are arranged. Inside the processing chamber 64, a lower electrode 65 also serving as a susceptor as a holding jig for holding the wafer 4 is arranged concentrically with the base 62, and the lower electrode 65 is an upper electrode facing upward. It is configured to generate plasma between them. The lower electrode 65 is supported by a support 66, and the support shaft 66 is moved up and down by a vertical movement device (not shown) and rotated by a rotation drive device (not shown). ing. A part of the base 62 is provided with an inlet / outlet 67 for taking in / out a wafer as an object to be processed. A load lock chamber (not shown) is adjacently connected to the inlet / outlet 67, and a wafer passes through the inlet / outlet 67 between the inlet / outlet lock chamber and the processing chamber 6 and a handling device (not shown). It is designed to automatically carry in and out one by one. A cap 68 is attached to the access port 67, and the cap 68 is configured to open and close the access port 67.

A gas supply unit 7 connected to a gas supply path 8 is provided to the upper electrode 69 so as to supply gas to the inside of the upper electrode 69, and gas is supplied to the upper electrode 69. A large number of outlets 6 9 a that blow out toward 5 I have. The gas supply path 8 is connected to a processing gas supply device 9 A for supplying an etching gas (hereinafter referred to as a processing gas) as a processing gas, and the processing gas supply device 9 A is a dry etching as a processing. It is configured to supply a processing gas under the control of a processing sequence controller 10A for controlling the processing. Further, a cleaning gas supply device 11 for supplying an etching gas (hereinafter referred to as a cleaning gas) for dry cleaning is connected to the gas supply path 8, and the cleaning gas supply device 11 is a cleaning gas control unit. It is configured to supply a cleaning gas under the control of 12. An exhaust port 14 is opened in the base 62, and an exhaust path 15 is connected to the exhaust port 14. A vacuum exhaust device 16 is connected to the exhaust path 15, and the vacuum exhaust device 16 is controlled by a pressure control unit 17 so that the processing chamber 64 can be evacuated to a predetermined degree of vacuum. Have been. The pressure controller 17 is connected to the processing sequence controller 1OA.

Outside the base 62 and the cover 63, a plurality of thermocouples 20 as temperature sensors for detecting the end point of cleaning are arranged in close proximity to the processing chamber 64, respectively.The thermocouple 20 has a temperature of §2. The monitoring unit 21 is in contact with the gun. The thermocouple 20 is arranged so that the temperature distribution of the processing chamber 64 can be measured over the whole. Outside the base 62 and the cover 63, there are multiple radiation thermometers 2OA as temperature sensors for detecting the cleaning end point, and the temperature of the lower electrode 65 and upper electrode 69 in the processing chamber 64 is measured in a non-contact manner The thermometer 2 OA is also connected to the temperature change monitoring unit 21. The radiation thermometer 2OA is also arranged so as to be able to measure the entire temperature distribution of the processing chamber 64. The output terminal of the temperature change monitoring unit 21 is connected to one input terminal of the end point determination unit 22, and the other input terminal of the end point determination unit 22 is connected to the end point table storage unit 23. In addition, the output of the end point The force end is in contact with the cleaning gas control unit 12, and the end point determination unit 22 sends the determination result to the cleaning gas control unit 12.

Next, a dry cleaning method for the dry etching apparatus according to the above-described configuration is performed in a case where a polysilicon gate (see FIG. 3) is formed by dry etching in a gate forming step of a method for manufacturing a silicon (Si) gate nMOS transistor. Will be described.

The wafer 4 as an object to be processed on which a doped silicon film is formed and a mask is formed by a lithography process is carried into a processing chamber 64, and as shown in FIG. It is placed on. The inside of the processing chamber 6 is evacuated to a predetermined degree of vacuum (1 to 100 Pa) by the vacuum exhaust device 16. Further, a microwave power is applied between the lower electrode 65 and the upper electrode 69 to generate plasma.

Next, as a processing gas for etching the doped polysilicon film, for example, carbon tetrafluoride (CF ₄ ) is supplied into the processing chamber 64 by the processing gas supply device 9A. The processing gas flows into the gas supply port 7 formed in the upper electrode 69 and is blown out from the outlet 69 a of the upper electrode 69 toward the wafer 4 held by the lower electrode 65. The blown processing gas flows downward while contacting the wafer 4, and is exhausted from the exhaust port 14. At this time, the processing gas that comes into contact with the wafer 4 is chemically activated by the plasma, so that the processing gas becomes a stripe that etches the doped polysilicon film. Here, the doped polysilicon film is etched by the following reaction formula. In the following formula, since monosilane is volatile, it is evaporated and evacuated, and a predetermined unmasked region of the doped silicon film is etched.

S i + F * → S i F ₄ † When the predetermined time has elapsed, the processing gas supply device 9A stops supplying the processing gas under the control of the processing sequence control unit 1OA. Processing Sequence Control Unit 1 Cap 6 is opened under the control of OA, and a wafer 4 having a predetermined region of the doped polysilicon film dry-etched is picked up from lower electrode 65 by a handling device (not shown) and processed in a processing chamber 64. It is carried out from. Next, the next wafer 4 is carried into the processing chamber 64 and held by the lower electrode 65. Thereafter, the above operation is repeated.

By the way, in a dry etching apparatus, a substance generated by an etching reaction between an etching gas and a film to be processed is deposited on an inner surface of a processing chamber or an outer surface of an upper electrode or a lower electrode (hereinafter, referred to as a deposited film). If the deposited film reaches a certain thickness, it will be sculpted and adhere to the wafer being processed, causing product defects. Therefore, cleaning is also required in dry etching equipment. In the embodiment, when the deposited film of the doped polysilicon reaches a certain thickness, the deposited film is deposited on the processing chamber 64, the lower electrode 65, and the upper electrode 69 by performing dry cleaning over the entire inside of the processing chamber 64. The deposited film is removed.

When the thickness of the deposited film of doped polysilicon deposited on the inner surface of the processing chamber 64 and the outer surfaces of the lower electrode 65 and the upper electrode 69 reaches a predetermined value, the processing sequence controller 1 OA switches from processing mode to dry cleaning mode. For example, in the case of a deposited film of doped polysilicon in a single-wafer dry etching apparatus, the film thickness at which dry cleaning is started is lOj ^ m. When the mode is switched to the dry cleaning mode, the loading of the wafer 4 into the processing chamber 64 is interrupted, and the pressure inside the processing chamber 64 is reduced by the pressure in the processing operation to a vacuum exhaust unit controlled by the pressure control unit 17. Maintained by evacuation of 16.

When the loading of wafers 4 into processing chamber 64 is interrupted, the cleaning gas system The cleaning gas is supplied from the cleaning gas supply device 11 into the processing chamber 64 through the gas supply path 8 under the control of the control unit 12. The cleaning gas flows in from the gas supply port 7 of the upper electrode 69 and blows out from the outlet 69a of the upper lemon 69. The blown-out cleaning gas flows downward while contacting the deposition film deposited on the inner surface of the processing chamber 64 and the outer surfaces of the lower electrode 65 and the upper electrode 69, and is exhausted from the exhaust port 14 by the vacuum exhaust device 16 . When chlorine trifluoride (C 1 F ₈ ) gas is used as a cleaning gas, the deposited film of doped polysilicon is etched by the following reaction formula.

2S i + 4C 1 F _s → S i F ₄ + S i C +2 F ₂ + C 1 ₂ 2 P ₂ 0 ₆ + 2C l F _s → 2PFs +50 ₂ + C 1 ₂

Note that in the formula, 0 is oxygen in the gate silicon oxide film.

The reaction product of the etching is exhausted from the exhaust port 14 by the vacuum exhaust device 16 together with the excess cleaning gas. The deposited film is gradually removed by etching, and the inner surface of the processing chamber 64 and the outer surfaces of the lower electrode 65 and the upper electrode 69 are relatively cleaned.

The end point of the dry cleaning is accurately determined by monitoring the temperature change inside the processing chamber 64 during the dry cleaning by the temperature change monitoring unit 21. In the present embodiment in which a change in the internal temperature of the processing chamber 64 is detected at a plurality of locations, the peak of each temperature change curve is monitored, and the end point determination unit 22 determines the end point of the last peak. As described above, the end point is determined by the end point determination unit 22, and a command to end the dry cleaning is issued to the cleaning gas control unit 12. When the cleaning gas control unit 12 controls the cleaning gas supply unit 11, the The supply of the cleaning gas is stopped. If necessary, purge gas such as nitrogen gas is supplied to the cleaning gas The gas is supplied from the processing gas supply device 9 A into the processing chamber 64. As a result, the etching reaction on the deposited film is almost eliminated, and the dry cleaning is completed.

Thereafter, the dry etching process is restarted by the dry-etched dry etching apparatus. After restarting the dry etching process, the processing chamber 64, lower electrode 65, and upper electrode of the dry etching equipment

Since the deposited film 69 is dry-cleaned to a predetermined thickness, it does not fall off and the deposited film does not contaminate the wafer 4 as an object to be processed.

FIG. 14 is a block diagram showing a micro mouth dry etching apparatus used in the method of manufacturing IC according to the tenth embodiment of the present invention.

The tenth embodiment differs from the first embodiment in that a microwave dry etching apparatus is used. Microwave dry etching equipment

Reference numeral 70 denotes a dry etching apparatus which aims at achieving both high plasma density and a sufficiently long average free process by resonance of a microphone mouth wave and a magnetic field.Since its configuration, operation and effect are the same as those of the dry etching apparatus 61 described above, The description is omitted. In FIG. 14, reference numeral 71 denotes a solenoid coil, reference numeral 72 denotes a high-frequency power supply, and reference numeral 73 denotes a waveguide connected to a magnetron (not shown) to guide a microphone α-wave.

Although the invention made by the inventor has been specifically described based on the embodiment, the present invention is not limited to the embodiment, and it is needless to say that various modifications can be made without departing from the gist of the invention. Nor.

For example, the deposited film to be subjected to dry cleaning is not limited to those formed of silicon nitride and doped polysilicon, but may be formed of metal such as silicon oxide, aluminum, tungsten, titanium, tantalum, molybdenum, or the like. May be available. The etching gas used for dry cleaning is not limited to fluorine gas or chlorine trifluoride gas, but is a mixture of hydrogen fluoride (HF) and nitrogen trifluoride (NF ₈ ) to which fluorine (F ₂ ) is added. It may be gas or the like.

In the above description, the case where the invention made by the present inventor is mainly applied to the CVD and dry etching processes, which are the fields of application that are the background, has been described. However, the present invention is not limited to this, and the epitaxial growth process is not limited thereto. It can also be applied to thin film formation processing such as sputtering, sputtering, and vapor deposition, as well as ion irradiation such as doping and focusing ion beam processing. In short, the present invention can be applied to all processes in which a process is performed in a processing room and a deposited film is formed in a processing room or a jig in the IC manufacturing method.

Industrial applicability

As described above, the method for manufacturing a semiconductor integrated circuit device according to the present invention can accurately terminate dry cleaning when a deposited film due to a reaction product or the like is dry cleaned. It can be widely used in the whole method of manufacturing the device.

Claims

The scope of the claims

1. A processing step in which processing on a semiconductor wafer is repeatedly performed inside the processing chamber, and the inside of the processing chamber is removed by removing a deposition film deposited by the processing inside the processing chamber with an etching gas. A method for manufacturing a semiconductor integrated circuit device, comprising:

A semiconductor integrated circuit device, wherein a temperature change in the processing chamber is measured directly or indirectly during the dry cleaning, and a time point at which the dry cleaning is terminated is determined based on the measured data. Manufacturing method.

2. The method for manufacturing a semiconductor integrated circuit device according to claim 1, wherein the time point at which the dry cleaning is completed is set so that the deposited film remains thin on the inner surface of the processing chamber.

3. The method for manufacturing a semiconductor integrated circuit device according to claim 1, wherein a time point at which the temperature change reaches a peak is determined as a time point at which the dry cleaning is completed.

4. The temperature change in the processing chamber is measured at a plurality of locations, and the last peak time of the temperature changes measured at the plurality of locations is a time when the dry cleaning is completed. 2. The method for manufacturing a semiconductor integrated circuit device according to claim 1.

5. The manufacturing of the semiconductor integrated circuit device according to claim 1, wherein a point in time when a predetermined period has elapsed from a point in time when the temperature change reaches a peak is determined as a point in time when the dry cleaning is ended. Method.

6. A table obtained from an experiment or a past run is compared with the current data of the temperature change, and the time at which the dry cleaning is completed is determined. 2. The method for manufacturing a semiconductor integrated circuit device according to claim 1, wherein the method is determined.

7. The semiconductor integrated circuit device according to claim 1, wherein the temperature change is represented by a function, and a point in time at which the inclination changes when the temperature decreases is determined as a point in time when the dry cleaning ends. Manufacturing method.

8. The dry cleaning is performed in a state where the holding jig for holding the semiconductor wafer is accommodated in the processing chamber, whereby the holding jig is simultaneously dry-cleaned. 3. The method for manufacturing a semiconductor integrated circuit device according to item 1.

9. The method for manufacturing a semiconductor integrated circuit device according to claim 1, wherein the processing step is a thin film forming step of forming a thin film on the semiconductor wafer.

10. The manufacturing of a semiconductor integrated circuit device according to claim 1, wherein said processing step is a dry etching step of dry etching a predetermined area of a thin film formed on said semiconductor wafer. Method.