JP5933347B2 - Silicon carbide removal method - Google Patents

Description

The present invention relates to a silicon carbide removal how.

  Silicon carbide composed of silicon and carbon is used in various fields as an important ceramic material. In particular, it is expected as a basic material for electronic parts for automobiles, for example, because it has characteristics as a semiconductor, and can produce an element that operates at low power consumption and high temperature.

In the silicon carbide film forming apparatus used when forming the silicon carbide, after silicon carbide is formed, it is formed on the inner wall (inner surface) of the film forming chamber (reaction vessel) which is one of the members of the silicon carbide film forming apparatus. Further, silicon carbide was deposited, and there was a possibility that the silicon carbide would become a generation source of particles.
For this reason, a method of removing silicon carbide (deposited layer or deposit) deposited on the inner wall of the film forming chamber by periodic gas cleaning has been proposed.

  In Patent Document 1, a silicon carbide body is disposed on an electrode in a vacuum chamber, a mixed gas of fluorine-based gas and oxygen is supplied into the vacuum chamber, and plasma is generated between the electrode and the counter electrode. In the method of reactive ion etching of a silicon carbide body, there is provided a silicon carbide body etching method in which a silicon carbide body is placed on an electrode in a state of being placed on a dish made of quartz glass or silicon having a size approximate to the area of the electrode. It is disclosed.

  In Patent Document 2, a source gas as a raw material for film formation is supplied to a processing container having a holding table for holding a substrate to be processed in an internal decompression space, and the substrate to be processed is induction-heated by a coil. A film forming apparatus for forming a film by epitaxial growth on the substrate to be processed, wherein the cleaning container is supplied with a cleaning gas, and the cleaning gas is excited by plasma to clean the inside of the processing container. A film forming apparatus is disclosed.

  Further, Patent Document 2 discloses a substrate processing method using a film forming apparatus having a processing container provided with a holding table for holding a substrate to be processed in an internal decompression space, and a raw material gas used as a film forming material is processed into the processing container. In addition, the substrate to be processed is induction-heated by a coil to form a film by epitaxial growth on the substrate to be processed, a cleaning gas is supplied into the processing container, and the cleaning gas is supplied to plasma. A substrate processing method is disclosed that includes a cleaning step of performing excitation to clean the inside of the processing container.

  Patent Document 3 discloses a method for cleaning a plasma CVD apparatus for depositing a desired film on a substrate by vapor deposition in a plasma CVD (Chemical Vapor Deposition) reaction chamber, and in a region other than on the substrate in the reaction chamber. A cleaning method is disclosed in which an inert gas is introduced from outside and sprayed onto dust containing vapor deposition powder or flakes that are stably adhered, and the dust is blown off.

JP-A-7-161690 JP 2009-117399 A JP 2001-131753 A

  By the way, when forming a silicon carbide film using a silicon carbide film forming apparatus, a high temperature process of 1500 ° C. or higher is performed, so that most of the members constituting the inner surface of the film forming chamber are composed of components similar to the deposits. Made of high heat-resistant material such as silicon carbide or carbon.

For this reason, in the methods of Patent Documents 1 and 2 in which etching is performed on silicon carbide by converting gas into plasma by a plasma generation unit integrated with the film formation chamber, the inner surface of the film formation chamber directly touches the plasma discharge. It is difficult to remove deposits containing silicon carbide.
That is, since it is difficult to ensure the selection ratio, there is a problem that the members constituting the inner surface of the film forming chamber are also etched.

  Further, in the apparatus configurations of Patent Documents 1 and 2, when using the SiC epi process, epi is performed under a thermal condition of about 1500 ° C., so it is difficult to provide an electrode for cleaning in the reaction chamber.

In addition, the method of Patent Document 3 has a problem that deposits that are hardly adhered by a high-temperature process of 1500 ° C. or higher, such as silicon carbide, cannot be sufficiently removed by spraying an inert gas.
For these reasons, in Patent Documents 1 to 3, it has been difficult to accurately remove deposits containing silicon carbide attached to members constituting the inner surface of the deposition chamber after the silicon carbide film is formed.

  Further, in Patent Documents 1 to 3, it cannot be determined whether or not the silicon carbide constituting the deposit has been removed (in other words, there is no end point detection system that detects the time when the removal of the deposit is completed). In the case where the deposit removal process is performed for a longer processing time, there are problems that productivity is lowered and members constituting the inner surface of the film forming chamber are damaged.

Therefore, the present invention can efficiently remove deposits attached to the inner surface of the deposition chamber in-situ without reducing the productivity while suppressing damage to the inner surface of the deposition chamber. and to provide a Do silicon carbide removal how.

  In order to solve the above-described problem, according to the first aspect of the present invention, after the substrate on which the silicon carbide film is formed is taken out from the film formation chamber in which the deposit containing silicon carbide is adhered to the inner surface, the film formation is performed. A first removal treatment for heating the inner surface of the chamber to a temperature of 350 ° C. or higher, supplying plasma-containing fluorine-containing gas into the heated deposition chamber, and removing the deposit; After the removing process, an inert gas is sprayed on the inner surface of the film forming chamber to sequentially repeat a second removing process for removing the attached substance, and an exhaust gas discharged from the film forming chamber. And a step of analyzing the concentration of the predetermined gas contained, and the deposit removal step is terminated when the concentration of the predetermined gas becomes a predetermined threshold value or less. Provided That.

  Moreover, according to the invention which concerns on Claim 2, in the said deposit | attachment removal process, the order of a said 1st removal process and a said 2nd removal process is replaced, The silicon carbide removal of Claim 1 characterized by the above-mentioned. A method is provided.

  According to the invention of claim 3, in the second removal process, after the pressure in the film formation chamber is reduced to atmospheric pressure, the inert gas is sprayed on the inner surface of the film formation chamber. A method for removing silicon carbide according to claim 1 or 2 is provided.

  According to the invention of claim 4, in the first removal process, the film forming chamber is heated to 350 to 400 ° C. 5. A method for removing silicon carbide is provided.

  According to the invention of claim 5, before the deposit removing step, the step of forming the silicon carbide film on the substrate; and before the deposit removing step, the silicon carbide film is formed. And a step of removing the substrate from the deposition chamber after the step of forming the film, wherein the step of forming the silicon carbide film and the step of removing the substrate are sequentially repeated. A method for removing silicon carbide according to any one of 1 to 4 is provided.

  Moreover, according to the invention which concerns on Claim 6, after the said deposit removal process, the process of forming the said silicon carbide film | membrane and the process of taking out the said board | substrate are performed, The silicon carbide removal of Claim 5 characterized by the above-mentioned A method is provided.

  The invention according to claim 7 further includes a step of heating and purging the inside of the deposition chamber with hydrogen after the deposit removing step and before the step of forming the silicon carbide film. A method for removing silicon carbide according to claim 6 is provided.

  According to an eighth aspect of the present invention, there is provided the silicon carbide removing method according to the seventh aspect, wherein in the step of heating and purging, the hydrogen is turned into plasma.

According to the onset bright, by heating the deposition chamber to a temperature above 350 ° C., separately, without preparing silicon carbide removal device for removing consisting of silicon carbide deposits at in-situ It becomes possible to remove the silicon carbide constituting the deposit by the fluorine-containing gas which has been set to a temperature of 350 ° C. or higher and is plasmatized.

  In addition, by spraying an inert gas on the inner surface of the film forming chamber, of the adhering material adhering to the inner surface of the film forming chamber, the adhering material having reduced adhesion to the inner surface of the film forming chamber is peeled off from the inner surface of the film forming chamber. It becomes possible.

  That is, a first removal treatment for removing deposits made of silicon carbide chemically with a fluorine-containing gas that is set to a temperature of 350 ° C. or more and is plasmatized, and an inert gas is sprayed on the inner surface of the film forming chamber. In combination with the second removal treatment for physically removing the deposit, it is repeatedly performed, so that the deposit can be obtained in-situ without separately preparing a silicon carbide removing device for removing silicon carbide. Can be efficiently removed.

Further, the concentration of a predetermined gas contained in the exhaust gas discharged from the film forming chamber is analyzed, and when the concentration of the predetermined gas becomes a predetermined threshold value or less, the deposit removal step (first and second steps) By ending the step of repeatedly performing the removal process, it is possible to further suppress the first removal process after the deposit is removed.
Thereby, damage to the inner surface of the film forming chamber caused by the plasma-containing fluorine-containing gas can be suppressed.

  Also, it is necessary to analyze the concentration of the predetermined gas contained in the exhaust gas discharged from the film formation chamber and terminate the deposit removal process when the concentration of the predetermined gas falls below a predetermined threshold value. As described above, the deposit removing process (specifically, the first removing process) is not performed, and the processing time of the deposit removing process is shortened, so that a decrease in productivity can be suppressed.

In other words, according to the present onset bright, efficiency in terms of suppressed damage to the inner surface of the deposition chamber, without reducing productivity, with in-situ, the deposits adhering to the inner surface of the deposition chamber in a short time Can be removed well.

It is a figure which shows schematic structure of the silicon carbide film-forming apparatus which concerns on embodiment of this invention. It is a figure which shows the flowchart for demonstrating the silicon carbide removal method of this Embodiment using the silicon carbide film-forming apparatus shown in FIG. Relationship between the number of repetitions of the first and second removal treatments and the concentration of silicon tetrafluoride and carbon tetrafluoride contained in the exhaust gas, and the number of repetitions of the first removal treatment and tetrafluoride contained in the exhaust gas It is a figure which shows the relationship between the density | concentration of silicon, and the density | concentration of carbon tetrafluoride.

  Embodiments to which the present invention is applied will be described below in detail with reference to the drawings. The drawings used in the following description are for explaining the configuration of the embodiment of the present invention, and the size, thickness, dimension, etc. of each part shown in the drawing are the same as the dimensional relationship of an actual silicon carbide film forming apparatus. May be different.

(Embodiment)
FIG. 1 is a diagram showing a schematic configuration of a silicon carbide film forming apparatus according to an embodiment of the present invention.
Referring to FIG. 1, a silicon carbide film forming apparatus 10 of the present embodiment includes a film forming chamber 11, a fluorine-containing gas supply unit 13, a plasma generating unit 15, a heater (not shown), an inert gas A gas supply unit 18, a nozzle unit 19, a vacuum pump 22, a gas pipe 23, an exhaust gas analyzer 25, and a control unit 26 are included.

The silicon carbide film forming apparatus 10 is an apparatus for forming a silicon carbide film on a substrate (not shown) placed in the film forming chamber 11. Therefore, when a silicon carbide film is formed on the substrate, deposits containing silicon carbide adhere to the inner surface 11a of the deposition chamber 11 (in other words, the surface of the member constituting the inner surface 11a of the deposition chamber 11). .
The “attachment” referred to here is a mixture in which silicon and carbon are mixed, not a pure substance only of silicon carbide, having a poor surface state (for example, surface roughness Ra of 10 or more).

When the deposit is removed, the film-forming chamber 11 is supplied with a plasma-containing fluorine-containing gas in a first removal process shown in STEP 6 of FIG. 2 described later.
For this reason, the member (member to which the deposit | attachment adhered) which comprises the inner surface 11a of the film-forming chamber 11 is comprised with the material which has sufficient tolerance with respect to fluorine-containing gas.

  Further, in the film forming process of the silicon carbide film, it is necessary to heat to a high temperature of 1500 ° C. or higher due to thermal characteristics. Therefore, a material that is stable at a temperature of 1500 ° C. or higher is used as the material of the member that forms the inner surface 11a of the film forming chamber 11.

For the above reasons, as a material of the member constituting the inner surface 11a of the film forming chamber 11, for example, a heat resistant material such as silicon carbide, tantalum carbide, silicon nitride, boron nitride, and carbon may be used.
Further, considering the cost, it is preferable to use a material for the member constituting the inner surface 11a of the film formation chamber 11 in which the base material is carbon and the surface of the base material is coated with silicon carbide.

In this case, as the silicon carbide coat, for example, when a surface state is good (for example, surface roughness Ra is less than 10), a pure substance made of only silicon carbide, and having a thickness of 200 μm or more is used. Good.
Carbon-silicon carbide coated members are widely used in semiconductor manufacturing apparatuses for forming devices on silicon substrates, and have a track record as materials having strong corrosion resistance against fluorine-containing gases.

  The fluorine-containing gas supply unit 13 is connected to the plasma generation unit 15 and supplies fluorine-containing gas to the plasma generation unit 15. The plasma-containing fluorine-containing gas mainly removes silicon (silicon component) contained in silicon carbide constituting the deposit when the temperature of the atmosphere in the film forming chamber 11 is about 300 ° C.

  Further, since the fluorine-containing gas also reacts with carbon (carbon component) contained in the deposit when the atmospheric temperature is 350 or higher, the silicon component and the carbon component can be removed only with the fluorine-containing gas.

Examples of the fluorine-containing gas include fluorine (F ₂ -GWP: 0), hydrogen fluoride (HF-GWP: 0), hydrofluorocarbon (CxHyFz (x, y, z are integers of 1 or more), for example, CH ₃ F -GWP-97) including at least one can be used.

Examples of the fluorine-containing gas include fluorocarbon (CF ₄ -GWP: 7,390, C ₂ F ₆ -GWP: 12,200), sulfur hexafluoride (SF ₆ -GWP: 22,800), and three fluorine. Nitrogenide (NF ₃ -GWP: 17,200), chlorine trifluoride (ClF ₃ -GWP: 0), carbonyl difluoride (COF ₂ -GWP: 1), etc. can also be used.
However, since these gases have a large global warming potential (GWP), they are not so preferable from the viewpoint of global warming. The fluorine-containing gas is preferably a low environmental load gas such as F ₂ or HF having a small GWP value.

The plasma generation unit 15 is connected to the fluorine-containing gas supply unit 13. The plasma generating unit 15 is supplied with a fluorine-containing gas.
The plasma generation unit 15 converts the fluorine-containing gas into plasma and supplies the plasma-containing fluorine-containing gas into the film forming chamber 11.

  As the plasma generator 15, a commercially available general plasma generator can be used. The plasma generator 15 may be an oscillator of 200 kHz to 2.45 GHz. The specifications of the plasma generator 15 are determined by the composition, flow rate, pressure, etc. of the gas supplied to the plasma generator 15.

In order to discharge a stable plasma, the pressure of the fluorine-containing gas supplied to the plasma generator 15 is preferably 10 torr or less.
In addition, it is possible to generate a large amount of radicals and the like by flowing a large amount of fluorine-containing gas, but in order to fully utilize the radicals and the like, it is necessary to reduce the pressure in order to avoid annihilation due to the collision of radicals. .

For this reason, when the flow rate of the fluorine-containing gas supplied to the plasma generation unit 15 is reduced to be processed at 1 torr or less, the flow rate of the fluorine-containing gas supplied to the plasma generation unit 15 is increased to be processed at 10 torr or less. Two cases of processing can be considered.
The flow rate and pressure of the fluorine-containing gas supplied to the plasma generator 15 are the optimum conditions in consideration of the results when the sample is actually processed, various conditions associated with the plasma generation conditions, and the conditions around the equipment. Can be appropriately selected.

The heater (not shown) is for heating the film forming chamber 11 (specifically, a member constituting the inner surface 11a of the film forming chamber 11) to a temperature of 350 ° C. or higher.
As the heater, a hot wall type heater that warms the entire film forming chamber 11 may be used, or a cold wall type heater that warms only the heating target member and heats the deposit by the heat transfer. It may be used.

As the heater, a cold wall type heater is preferable from the viewpoint of preventing contamination from the surroundings due to the removal treatment of deposits.
Further, as the heater, the same heater as that used when the silicon carbide film is formed may be used.

  Therefore, by providing a heater (not shown) and heating the film forming chamber 11 with the heater, the reaction between the plasma-containing fluorine-containing gas and silicon carbide constituting the deposit can be promoted. Therefore, the deposit made of silicon carbide can be removed with sufficient removal capability.

  In addition, when removing the deposit using the plasma-containing fluorine-containing gas, it is preferable to use a heater to heat the deposition chamber 11 so that the temperature in the range of 350 to 400 ° C.

When the temperature of the film forming chamber 11 is lower than 350 ° C., the deposit made of silicon carbide cannot be sufficiently removed.
Further, when the temperature of the film forming chamber 11 is higher than 400 ° C., the reaction between the plasma-containing fluorine-containing gas and the silicon carbide coat (film forming chamber 11) is promoted, and therefore, the selection between the deposit and the silicon carbide coat is required. It is not possible to secure superiority.

  For the above reason, when using a plasma-containing fluorine-containing gas, the inner surface of the film-forming chamber 11 caused by the plasma-containing fluorine-containing gas is set by setting the temperature of the film-forming chamber 11 within a range of 350 to 400 ° C. The silicon carbide constituting the deposit can be efficiently removed while suppressing damage to 11a.

  In this way, the fluorine-containing gas supply unit 13 for supplying the fluorine-containing gas and the fluorine-containing gas supply unit 13 are connected to convert the fluorine-containing gas into plasma and to convert the plasma-containing fluorine-containing gas into the film forming chamber 11. Silicon carbide removal for removing silicon carbide separately by having plasma generator 15 to be supplied and a heater (not shown) for heating inner surface 11a of film formation chamber 11 to a temperature of 350 ° C. or higher. Without preparing an apparatus, it is possible to efficiently remove silicon carbide constituting the deposit by the fluorine-containing gas that has been plasmatized in-situ.

  In addition, the distance between the inner surface 11a of the film forming chamber 11 and the plasma generator 15 is preferably 100 cm or less. Thereby, it becomes possible to ensure a sufficient etching rate of silicon carbide constituting the deposit.

  Further, in order to efficiently turn the fluorine-containing gas, which is a cleaning gas (a gas for removing deposits), into plasma, an inert gas such as Ar, He, Ne or the like is added as a discharge gas to the fluorine-containing gas. Also good.

The inert gas supply unit 18 is disposed outside the film forming chamber 11. The inert gas supply unit 18 is connected to the nozzle unit 19 and supplies an inert gas (for example, Ar, He, N ₂ ) to the nozzle unit 19.

  The nozzle unit 19 is disposed in the film forming chamber 11. The nozzle unit 19 is configured to be movable and / or rotatable, and sprays the inert gas supplied from the inert gas supply unit 18 onto the inner surface 11 a of the film forming chamber 11.

  Thus, by having the inert gas supply unit 18 that supplies the inert gas and the nozzle unit 19 that is connected to the inert gas supply unit 18 and blows the inert gas to the inner surface 11a of the film forming chamber 11. Among the deposits attached to the inner surface 11 a of the film forming chamber 11, it is possible to peel the deposit with reduced adhesion to the inner surface 11 a of the film forming chamber 11 from the inner surface 11 a of the film forming chamber 11.

  Therefore, by combining the method of chemically removing deposits using a plasma-containing fluorine-containing gas and the method of physically removing deposits by blowing an inert gas, Compared with the case where the deposit is removed using only the gas, the deposit can be removed in a short time, and the productivity can be improved.

In FIG. 1, only one nozzle portion 19 is illustrated, but a plurality of nozzle portions 19 may be arranged in the film forming chamber 11.
Moreover, the arrangement position of the nozzle part 19 is not limited to the arrangement position of the nozzle part 19 shown in FIG. The nozzle unit 19 may be disposed at a position where an inert gas can be efficiently blown onto the inner surface 11 a of the film forming chamber 11.

In addition, the flow rate and spray speed of the inert gas sprayed from the nozzle unit 19 may be a flow rate and spray speed at which the deposits with reduced adhesion to the film forming chamber 11 can be peeled off.
Specifically, the supply pressure of the inert gas injected from the nozzle unit 19 can be set to 0.1 to 0.2 MPaG, for example. At this time, when the pipe diameter is ¼ inch, the flow rate of the inert gas injected from the nozzle portion 19 is approximately 40 to 60 L / min.

In addition, the removal of the deposits using the inert gas may be performed in a vacuum state in the film formation chamber 11, but it is preferable to perform the removal in an atmospheric pressure state in the film formation chamber 11.
In the removal of deposits using the plasma-containing fluorine-containing gas, it is necessary to increase the flow rate of the inert gas in order to perform efficient air blowing with the pressure in the film forming chamber 11 being 10 torr or less.
For this reason, it is preferable to once remove the deposits using an inert gas after returning the pressure in the film forming chamber 11 to atmospheric pressure.

  The vacuum pump 22 is connected to the film forming chamber 11 and the gas pipe 23. The vacuum pump 22 exhausts the gas in the film forming chamber 11 and causes the gas pipe 23 to lead the exhaust gas. The gas pipe 23 is connected to the vacuum pump 22 and the exhaust gas analyzer 25.

The exhaust gas analyzer 25 is connected to the gas pipe 23 and electrically connected to the control unit 26. As the exhaust gas analyzer 25, for example, a non-dispersive infrared analyzer may be used.
Thus, by using a non-dispersion type infrared analyzer as the exhaust gas analyzer 25, the concentrations of silicon tetrafluoride and carbon tetrafluoride can be measured easily and at low cost.

  The exhaust gas analyzer 25 measures the concentration of at least one gas out of silicon tetrafluoride and carbon tetrafluoride contained in the exhaust gas, and transmits data relating to the measured concentration of the gas to the control unit 26.

  In addition, as the exhaust gas analyzer 25, for example, an analyzer such as a Fourier transform infrared spectrometer, an ultraviolet absorber, a mass spectrometer, or a gas chromatograph may be used.

  The control unit 26 is electrically connected to the fluorine-containing gas supply unit 13, the plasma generation unit 15, a heater (not shown), the inert gas supply unit 18, the nozzle unit 19, the vacuum pump 22, and the exhaust gas analyzer 25. Has been.

  Control unit 26 performs overall control of silicon carbide film forming apparatus 10. Based on the concentration of at least one gas (predetermined gas) of silicon tetrafluoride and carbon tetrafluoride transmitted from the exhaust gas analyzer 25, the control unit 26 includes a fluorine-containing gas supply unit 13 and a plasma generation unit. 15, the heater (not shown), the inert gas supply unit 18, the nozzle unit 19, the vacuum pump 22, and the exhaust gas analyzer 25 are controlled.

The control unit 26 includes a storage unit and a calculation unit (not shown) that are not shown. In the storage unit, a silicon tetrafluoride concentration threshold value and a carbon tetrafluoride concentration threshold value, which are predetermined gas concentration threshold values, and the number of substrates on which a silicon carbide film is to be formed are stored. Information is stored.
In addition, in the storage unit, information data on how many times the processing of the step of depositing silicon carbide and the step of removing the substrate from the deposition chamber 11 is performed (relating to a predetermined number of times) Information data) is stored.

  In addition, in a calculation unit (not shown) constituting the control unit 26, a deposit removing process for removing deposits (specifically, a first removal process using a plasma-containing fluorine-containing gas, and inertness) Determination of whether or not it is time to perform the step of the second removal process of blowing gas) and whether or not the deposition process for all the substrates on which the silicon carbide film is to be deposited has been completed. Is called. Control unit 26 controls silicon carbide film forming apparatus 10 based on these determinations.

In addition, when the calculation unit receives data on the concentration of at least one of silicon tetrafluoride and carbon tetrafluoride contained in the exhaust gas from the exhaust gas analyzer 25, the data on the concentration of the gas is stored in advance. It is determined whether or not the input gas gas concentration threshold value has been reached (specifically, a silicon tetrafluoride concentration threshold value, a carbon tetrafluoride concentration threshold value). Control unit 26 controls silicon carbide film forming apparatus 10 based on the determination.
Specifically, when the measured gas concentration is greater than a prestored threshold, the deposit removal process is continued, and when the measured gas concentration is less than the prestored threshold, The implementation of the deposit removal process is terminated.

Thus, based on the measurement result of the exhaust gas analyzer 25 that measures the concentration of a predetermined gas contained in the exhaust gas discharged from the film forming chamber 11, the fluorine-containing gas supply unit 13, the plasma generation A control unit 26 that controls the unit 15, a heater (not shown), an inert gas supply unit 18, a nozzle unit 19, a vacuum pump 22, and an exhaust gas analyzer 25. Analyzing the concentration of the predetermined gas contained in the exhaust gas to be discharged, and when the concentration of the predetermined gas falls below a predetermined threshold value, the deposit removal step (the step including STEPs 6 and 9 shown in FIG. 2) is completed. By doing so, it is possible to further suppress the first removal treatment after the deposits attached to the inner surface 11a of the film forming chamber 11 are removed. Damage of the inner surface 11a of the film forming chamber 11 due to the first removal processing using a scan can be suppressed.
Moreover, since it becomes possible to shorten the processing time of a deposit | attachment removal process, the fall of productivity can be suppressed.

  According to the silicon carbide film forming apparatus of the present embodiment, a heater (not shown) for heating inner surface 11a of film forming chamber 11 to a temperature of 350 ° C. or higher, and a fluorine-containing gas supply unit that supplies fluorine-containing gas 13 and a plasma generation unit 15 that is connected to the fluorine-containing gas supply unit 13 and converts the fluorine-containing gas into plasma and supplies the plasma-containing fluorine-containing gas into the film forming chamber 11. Without preparing a silicon carbide removing device for removing silicon carbide, silicon carbide constituting the deposit can be efficiently removed in-situ by the plasma-containing fluorine-containing gas.

  In addition, an inert gas supply unit 18 that supplies an inert gas and a nozzle unit 19 that is connected to the inert gas supply unit 18 and blows the inert gas to the inner surface 11a of the film forming chamber 11 are provided. Among the deposits attached to the inner surface of the film chamber, the deposit with reduced adhesion to the inner surface of the film forming chamber can be peeled off from the inner surface 11a of the film forming chamber 11.

  Therefore, the first removal process for chemically removing the deposits using the plasma-containing fluorine-containing gas and the second removal process for physically removing the deposits by blowing an inert gas are combined. As a result, it is possible to remove the deposit in a shorter time compared to the case where the deposit is removed using only the first removal treatment with the plasma-containing fluorine-containing gas, thereby improving productivity. it can.

  That is, according to the silicon carbide film forming apparatus 10 of the present embodiment, the damage of the inner surface 11a of the film forming chamber 11 is suppressed, and the film forming chamber 11 is formed in-situ without reducing the productivity. Deposits attached to the inner surface 11a can be efficiently removed in a short time.

  The silicon carbide film forming apparatus 10 may be a batch type film forming apparatus or a sheet type film forming apparatus.

  FIG. 2 is a flowchart for illustrating the silicon carbide removal method of the present embodiment using the silicon carbide film forming apparatus shown in FIG.

Next, with reference to FIG.1 and FIG.2, the silicon carbide removal method of this Embodiment is demonstrated.
First, when the process shown in FIG. 2 is started, in STEP 1, a substrate (not shown) is carried into the film forming chamber 11 of the silicon carbide film forming apparatus 10 shown in FIG. At this time, the substrate is placed on the substrate placement surface of a susceptor (not shown) accommodated in the film forming chamber 11. Thereafter, the process proceeds to STEP2.

  Next, in STEP 2, a silicon carbide film is formed on the surface of the substrate. At this time, the deposit made of silicon carbide adheres to the inner surface 11a of the film forming chamber 11 (specifically, the surface of the member constituting the inner surface 11a of the film forming chamber 11 and coated with silicon carbide). After completion of the silicon carbide film formation process, the process proceeds to STEP 3.

  Next, in STEP 3, the substrate on which the silicon carbide film is formed is taken out of the deposition chamber 11, and then the process proceeds to STEP 4.

Next, in STEP 4, it is determined whether or not the film forming process on all the substrates on which the silicon carbide film is to be formed has been completed. If it is determined in STEP 4 that the film forming process on all the substrates has been completed, the process illustrated in FIG. 2 ends.
On the other hand, if it is determined in STEP 4 that the film formation process on all the substrates has not been completed, the process proceeds to STEP 5.

Next, in STEP 5, it is determined whether or not the number of processes in the step of forming the silicon carbide film on the substrate and the step of taking out the substrate has reached a predetermined number of times previously input to the storage unit of the control unit 26. Is called.
If it is determined as No (not reached the predetermined number of times) in STEP 5, the process returns to STEP 1. On the other hand, if it is determined in STEP 5 that Yes (the predetermined number of times has been reached), the process proceeds to STEP 6.

  In STEP 5, as an example, a case where the number of processes in the process of forming a silicon carbide film on the substrate and the process of taking out the substrate is described as an example. It may be determined whether or not the total film thickness of the silicon carbide film formed in (1) has reached a preset film thickness.

  Next, in STEP 6, a first removal process is performed. Specifically, the temperature of the film forming chamber 11 is within a range of 350 to 400 ° C. (the deposit made of silicon carbide can be removed with a plasma-containing fluorine-containing gas, and the inner surface of the film forming chamber 11 can be removed. 11a is heated to a temperature at which damage can be suppressed), and then the plasma-containing fluorine-containing gas is supplied into the film forming chamber 11 to remove deposits attached to the inner surface 11a of the film forming chamber 11. .

  This makes it possible to remove the silicon carbide constituting the deposit by the plasma-containing fluorine-containing gas in-situ without separately preparing a silicon carbide removing device for removing silicon carbide.

If the temperature of the film formation chamber 11 is lower than 350 ° C., the deposit made of silicon carbide cannot be removed sufficiently. Further, when the temperature of the film forming chamber 11 is higher than 400 ° C., the reaction between the plasma-containing fluorine-containing gas and the silicon carbide coat starts to occur, so that it is not so much from the viewpoint of preferentially securing the deposit and coat selectivity. It is not preferable.
When the process in STEP 6 (first removal process) is completed, the process proceeds to STEP 7.

Next, in STEP 7, during the period from the start to the end of the first removal process, a predetermined amount included in the exhaust gas discharged from the film forming chamber 11 (gas discharged from the film forming chamber 11) by the gas analyzer 25. (Specifically, at least one gas of silicon tetrafluoride and carbon tetrafluoride) is analyzed.
Thereafter, the data regarding the concentration of the predetermined gas is transmitted to the control unit 26, and the process proceeds to STEP8.
In STEP 7, the predetermined concentration may be analyzed only at the end of the first removal process.

Next, in STEP 8, the concentration of the predetermined gas analyzed by the gas analyzer 25 in the control unit 26 is a predetermined threshold value (specifically, the threshold value of the concentration of silicon tetrafluoride or the concentration of carbon tetrafluoride). It is determined whether or not the threshold value is equal to or less than the threshold value.
If it is determined in STEP 8 that Yes (the concentration of the analyzed predetermined gas is equal to or lower than the predetermined threshold), the process of the deposit removal process is stopped, and the process proceeds to STEP 10.

  On the other hand, if it is determined No in STEP 8 (the concentration of the analyzed predetermined gas is greater than the predetermined threshold), the process proceeds to STEP 9 (second removal process).

  As described above, the concentration of the predetermined gas contained in the exhaust gas discharged from the film forming chamber 11 is analyzed, and when the concentration of the predetermined gas becomes a predetermined threshold value or less, the deposit removing step (STEP 6, 9). By completing the step (1), it is possible to further suppress the first removal process after the deposits attached to the inner surface 11a of the film forming chamber 11 are removed. Damage to the inner surface 11a of the film forming chamber 11 due to the fluorine-containing gas can be suppressed.

  In addition, by analyzing the concentration of a predetermined gas contained in the exhaust gas discharged from the film forming chamber 11, and when the concentration of the predetermined gas is equal to or lower than a predetermined threshold, the deposit removal process is terminated, Since the extraneous matter removing step is not performed more than necessary, and the processing time of the extraneous matter removing step is shortened, a decrease in productivity can be suppressed.

Next, in STEP 9, a second removal process is performed. Specifically, the deposits are removed by blowing an inert gas (for example, argon (Ar), helium (He), hydrogen (N ₂ )) onto the inner surface 11a of the film forming chamber 11.
As a result, among the deposits attached to the inner surface 11 a of the film formation chamber 11, it is possible to peel the deposits with reduced adhesion to the inner surface 11 a of the film formation chamber 11 from the inner surface 11 a of the film formation chamber 11.

  In the second removal process, it is preferable to spray an inert gas while moving or rotating the nozzle portion 19. As a result, it is possible to spray an inert gas over the entire inner surface 11 a of the film forming chamber 11.

  Further, the first removal process for chemically removing the deposits using the plasma-containing fluorine-containing gas and the second removal process for physically removing the deposits by blowing an inert gas are combined. As a result, it is possible to remove the deposit in a shorter time compared to the case where the deposit is removed using only the first removal process, and thus productivity can be improved.

In addition, the flow rate and spray speed of the inert gas sprayed from the nozzle unit 19 may be a flow rate and spray speed at which the deposits with reduced adhesion to the film forming chamber 11 can be peeled off.
Specifically, the supply pressure of the inert gas injected from the nozzle unit 19 can be set to 0.1 to 0.2 MPaG, for example. At this time, when the pipe diameter is ¼ inch, the flow rate of the inert gas injected from the nozzle portion 19 is approximately 40 to 60 L / min.

The second removal process (a process of blowing an inert gas into the film formation chamber 11) may be performed in a vacuum state in the film formation chamber 11, but the inside of the film formation chamber 11 is brought to atmospheric pressure. You should do it later.
In the removal of the deposits using the plasma-containing fluorine-containing gas, the pressure in the film forming chamber 11 is set to 10 torr or less. If efficient air blowing is performed at this pressure, it is necessary to increase the flow rate of the inert gas. is there.
For this reason, when the second removal process is performed, the second removal process may be performed after the pressure in the deposition chamber 11 is once returned to the atmospheric pressure.

The deposit removal process of the present embodiment is configured by repeatedly performing the first and second removal processes alternately. As described above, by repeatedly performing the first and second removal processes alternately, the removal efficiency of the deposits attached to the inner surface 11a of the film forming chamber 11 can be improved.
When the process in STEP 9 (second removal process) ends, the process returns to STEP 6.

Next, in STEP 10, the deposition chamber 11 is heated and purged with hydrogen (H ₂ ) after the deposit removing process is completed and before the silicon carbide film is formed on the substrate.
Thereby, the fluorine-containing gas component adhering to the inner surface 11a of the film forming chamber 11 can be removed.

As the heating temperature when the inside of the film forming chamber 11 is heated and purged with hydrogen (H ₂ ), the temperature of the film forming chamber 11 at the time of the first removal process of STEP 6 may be continued as it is, The temperature may be set slightly higher than the temperature of the film forming chamber 11 during the removal process.
Note that hydrogen (H ₂ ) used for the heating purge may be diluted with a rare gas such as Ar or He. Alternatively, the heat purge may be performed only with a rare gas.

Further, in STEP 10, when heating purging the inside of the deposition chamber 11 with hydrogen _{(H 2)} is preferably used hydrogen obtained by plasma _{(H 2).} Thereby, the fluorine-containing gas component adhering to the inner surface 11a of the film forming chamber 11 can be efficiently removed.
At this time, the hydrogenated hydrogen (H ₂ ) may be diluted with a rare gas such as Ar or He. Alternatively, the heat purge may be performed only with the plasmad rare gas.

In STEP 10, when the inside of the film forming chamber 11 is heated and purged, a gas other than hydrogen (H ₂ ) can be used. For example, a gas such as NH ₃ or SiH ₄ may be used.
Also in this case, as the heating temperature for the heat purge, the temperature of the film formation chamber 11 at the time of the first removal process of STEP 6 may be continued as it is, or the film formation chamber 11 at the time of the first removal process. It may be set to a temperature slightly higher than the temperature.
Note that a gas such as NH ₃ or SiH ₄ used in the heat purge process may be diluted with a rare gas such as Ar or He.
When the process in STEP 10 is completed, the process continues to STEP 11.

Subsequently, in STEP 11, it is determined whether or not the silicon carbide film has been formed on all the substrates. If it is determined in STEP 11 that No (the silicon carbide film is not formed on all the substrates), the process returns to STEP 1 and the processes in STEP 1 to STEP 3 are again performed (the process of forming the silicon carbide film on the substrate). Including the step).
If it is determined in STEP 11 that Yes (a silicon carbide film is formed on all the substrates), the process shown in FIG. 2 ends.

  According to the silicon carbide removing method of the present embodiment, carbonization for removing silicon carbide separately is performed by supplying plasma-containing fluorine-containing gas into film forming chamber 11 heated to 350 to 400 ° C. Without preparing a silicon removing device, it is possible to remove deposits made of silicon carbide while suppressing damage to the inner surface 11a of the film forming chamber 11 in-situ.

  Further, by spraying an inert gas onto the inner surface 11a of the film forming chamber 11, among the adhering materials adhering to the inner surface 11a of the film forming chamber 11, an adhering material having reduced adhesion to the inner surface 11a of the film forming chamber 11 is formed. The film chamber 11 can be peeled off from the inner surface 11a.

  That is, the first removal process for chemically removing the deposits by the plasma-containing fluorine-containing gas, and the second for physically removing the deposits by blowing an inert gas to the inner surface 11a of the film forming chamber 11. By sequentially performing the removal process, the deposits attached in the film forming chamber 11 are efficiently removed in-situ without separately preparing a silicon carbide removing device for removing silicon carbide. be able to.

Further, the concentration of a predetermined gas contained in the exhaust gas discharged from the film forming chamber 11 is analyzed, and when the concentration of the predetermined gas becomes a predetermined threshold value or less, the deposit removing process (first and second steps) By repeating the step of repeatedly performing the removing process, it is possible to further suppress the first removing process after the deposits attached to the inner surface 11a of the film forming chamber 11 are removed, so that the plasma Damage to the inner surface 11a of the film forming chamber 11 due to the activated fluorine-containing gas can be suppressed.
Moreover, since it becomes possible to shorten the processing time of a deposit | attachment removal process, the fall of productivity can be suppressed.

  That is, according to the silicon carbide removing method of the present embodiment, the inner surface 11a of the film forming chamber 11 can be in-situ without reducing the productivity while suppressing damage to the inner surface 11a of the film forming chamber 11. It is possible to efficiently remove deposits adhering to the surface in a short time.

  The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited to such specific embodiments, and within the scope of the present invention described in the claims, Various modifications and changes are possible.

For example, in this embodiment, the first removal process (STEP 6 process), the process of analyzing the concentration of a predetermined gas contained in the exhaust gas (STEP 7), and the second removal process (STEP 9) are performed in this order. Although the case has been described as an example, the processing is performed in the order of the second removal process (STEP 9), the first removal process (STEP 6 process), and the step of analyzing the concentration of a predetermined gas contained in the exhaust gas (STEP 7). You may go.
Also in this case, the same effect as in the present embodiment can be obtained.

(Example)
First, after repeating the step of forming a silicon carbide film on the substrate, a member constituting the inner surface 11a of the film forming chamber 11 (a member to which a deposit made of silicon carbide is attached) is evaluated to a size of 3 cm □. Sample A was cut out.
Next, the evaluation sample A to which the adhered matter was attached was placed in another film forming chamber 11 having no attached matter, and thereafter, a first removal process shown in STEP 6 of FIG. 2 was performed.

In the first removal process, the pressure in the film formation chamber 11 is set to 2 torr, the temperature in the film formation chamber 11 is maintained at 400 ° C., and then the fluorine trifluoride gas is contained in the film formation chamber 11. Nitrogen (flow rate of 100 sccm) was converted into plasma and supplied for 3 minutes to remove the deposit on the evaluation sample A.
At this time, 2.45 GHz (applied power 1000 W) was used as the condition of the plasma generation unit 15.

In addition, from the start to the end of the first removal process, the concentration of silicon tetrafluoride (predetermined gas) contained in the exhaust gas discharged from the film forming chamber 11 by the exhaust gas analyzer 25, and tetrafluoride The concentration of carbon (predetermined gas) was measured, and the end point of the deposit removal process was monitored.
As the exhaust gas analyzer 25, Fourier transform infrared spectroscopy manufactured by MIDAC was used. At this time, the cell length was 10 cm, the wave number resolution was 1 cm ⁻¹ , and the number of scans was 64. The interval between the first removal processes was set to 10 minutes.

Regarding the concentration of silicon tetrafluoride and the concentration of carbon tetrafluoride that are the end points of the deposit removal process, the members constituting the inner surface 11a of the film forming chamber 11 without deposits in advance have a size of 3 cm □. When the first removal process was performed on the cut out evaluation sample B, the concentration of silicon tetrafluoride and carbon tetrafluoride detected by the exhaust gas analyzer 25 was determined with reference to FIG.
Specifically, the concentration of silicon tetrafluoride used for the end point is 3 vol. ppm, and the concentration of carbon tetrafluoride used for the end point is 3 vol. ppm.

  Next, a second removal process shown in STEP 9 of FIG. 2 was performed. In the second removal process, after the first removal process is completed, the pressure in the film forming chamber 11 is once returned to the atmospheric pressure, and then inactivated from the nozzle portion 19 (see FIG. 1) on the surface of the evaluation sample A. Nitrogen gas was sprayed. At this time, the time for blowing nitrogen was set to 10 seconds. Further, the supply pressure of nitrogen in the second removal treatment was set to 0.1 MPaG.

Thereafter, the pressure in the film forming chamber 11 was returned to the pressure (specifically, 2 torr) when the first removal process was performed.
Further, while the second removal treatment with nitrogen was not performed, vacuum purge was performed with an inert gas (for example, nitrogen, argon, etc.).

In the Example, the measurement result of the density | concentration of the silicon tetrafluoride contained in the waste gas at the time of performing repeatedly the 1st and 2nd removal process and the density | concentration of carbon tetrafluoride is shown in FIG.
FIG. 3 shows the relationship between the number of repetitions of the first and second removal treatments, the concentration of silicon tetrafluoride and the concentration of carbon tetrafluoride contained in the exhaust gas, and the number of repetitions of the first removal treatment and the exhaust gas. It is a figure which shows the relationship between the density | concentration of silicon tetrafluoride and the density | concentration of carbon tetrafluoride.

(Reference example)
In the reference example, first, after repeatedly performing the process of forming the silicon carbide film on the substrate, the member constituting the inner surface 11a of the film forming chamber 11 (the member attached with the deposit made of silicon carbide) is 3 cm □. A sample C for size evaluation was cut out. As the sample C for evaluation, a sample having the same amount of deposit as the evaluation sample A of the example was used.

  In the reference example, the same process as in the example was performed except that the second removal process performed in the example was omitted. That is, in the reference example, the first removal treatment for removing the deposits attached to the evaluation sample C was repeatedly performed, and the concentrations of silicon tetrafluoride and carbon tetrafluoride contained in the exhaust gas were measured. The result is shown in FIG.

(Regarding the measurement results of gas concentration in Examples and Reference Examples)
Next, with reference to FIG. 3, the measurement result of the gas concentration of an Example and a reference example is demonstrated.
In the case of the reference example, even if the first removal treatment was repeated 14 times (182 minutes), the concentration of silicon tetrafluoride and the concentration of carbon tetrafluoride were 3 vol. It is not below ppm. That is, it has not been removed.

On the other hand, in the example, by repeating the first and second removal treatments 9 times, the concentration of silicon tetrafluoride and the concentration of carbon tetrafluoride are 3 vol. It was confirmed that the concentration was not more than ppm.
Moreover, in the case of the Example, it has confirmed that the time from the start to the completion | finish process of a deposit | attachment removal was 117 minutes.

From the above results, the deposit removal according to the embodiment is performed by combining the first removal treatment for removing the deposit with the plasma-containing fluorine-containing gas and the second removal treatment for spraying the deposit with an inert gas and repeatedly. It was found that the method can remove deposits in a shorter time than the deposit removal method of the reference example in which only the first removal treatment is repeated.
From this, it was confirmed that the productivity of the silicon carbide film forming apparatus 10 can be improved by using the deposit removal method of the example.

  Moreover, it turned out that the deposit removal method of an Example can remove a deposit by the 1st removal process of the frequency | count of the number of times smaller than the deposit removal method of a reference example from the said result. From this, it can be confirmed that by using the deposit removing method of the embodiment, damage to the inner surface 11a of the film forming chamber 11 caused by the plasma-containing fluorine-containing gas can be suppressed and the deposit can be removed with high accuracy. It was.

  The present invention is applicable to a silicon carbide removing method and a silicon carbide film forming apparatus for removing deposits attached to the inner surface of a film forming chamber.

DESCRIPTION OF SYMBOLS 10 ... Silicon carbide film-forming apparatus, 11 ... Film-forming chamber, 11a ... Inner surface, 13 ... Fluorine containing gas supply part, 15 ... Plasma generation part, 18 ... Inert gas supply part, 19 ... Nozzle part, 22 ... Vacuum pump, 23 ... gas pipe, 25 ... exhaust gas analyzer, 26 ... control unit

Claims (8)

After the substrate on which the silicon carbide film was formed was taken out of the film formation chamber in which the deposit containing silicon carbide adhered to the inner surface, the inner surface of the film formation chamber was heated to a temperature of 350 ° C. or higher, and the heated After supplying the plasma-containing fluorine-containing gas into the deposition chamber to remove the deposit, and after the first removal treatment, an inert gas is sprayed on the inner surface of the deposition chamber. A deposit removing step of sequentially repeating a second removal process for removing the deposit;
Analyzing the concentration of a predetermined gas contained in the exhaust gas discharged from the film formation chamber;
Have
The silicon carbide removal method, wherein the deposit removal step is terminated when the concentration of the predetermined gas becomes a predetermined threshold value or less.   The silicon carbide removing method according to claim 1, wherein in the deposit removing step, the order of the first removing process and the second removing process is switched.   3. The silicon carbide according to claim 1, wherein, in the second removal treatment, the inert gas is sprayed onto an inner surface of the film forming chamber after the pressure in the film forming chamber is reduced to atmospheric pressure. Removal method.   4. The method for removing silicon carbide according to claim 1, wherein, in the first removal process, the film forming chamber is heated to 350 to 400 ° C. 5. Forming the silicon carbide film on the substrate before the deposit removing step;
Before the deposit removal step and after the step of forming the silicon carbide film, removing the substrate from the deposition chamber;
Have
5. The method for removing silicon carbide according to claim 1, wherein the step of forming the silicon carbide film and the step of taking out the substrate are sequentially repeated.   6. The silicon carbide removing method according to claim 5, wherein after the deposit removing step, a step of forming the silicon carbide film and a step of taking out the substrate are performed.   7. The silicon carbide removing method according to claim 6, further comprising a step of heating and purging the inside of the film forming chamber with hydrogen after the deposit removing step and before the step of forming the silicon carbide film. .   8. The method for removing silicon carbide according to claim 7, wherein, in the heating and purging step, the hydrogen is turned into plasma.

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