JP2013042092A - Film-processing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for processing a film formed in the course of a film formation process.SOLUTION: The method comprises the following first to third steps, provided that the third step is carried out after the first and second steps are repeated in combination. In the first step, a substrate 7 is mounted on a spot-faced portion 8a of a susceptor 8 arranged in a reaction chamber, and then a reactive gas is introduced into the reaction chamber to form a SiC film 301 on the substrate 7. In the second step, an etching gas is introduced into the reaction chamber, and the etching gas is flowed from above the susceptor 8 down while rotating the susceptor 8 with the substrate 7 already removed therefrom, thereby removing the SiC film 301 which originates from the reactive gas and is formed over a stepped portion 8c extending from the spot-faced portion 8a of the susceptor 8 to its peripheral portion 8b. In the third step, the etching gas is introduced into the reaction chamber, thereby removing the SiC film 301 which originates from the reactive gas and is formed on the susceptor 8.

Description

  The present invention relates to a thin film processing method.

  Conventionally, an epitaxial growth technique has been used to manufacture a semiconductor element that requires a relatively large crystal film, such as a power device such as an IGBT (Insulated Gate Bipolar Transistor).

  In the vapor phase growth method used for the epitaxial growth technique, the pressure in the reaction chamber is set to normal pressure or reduced pressure while the substrate is placed in the reaction chamber. Then, a reactive gas is supplied into the reaction chamber while heating the substrate. Then, a gas undergoes a thermal decomposition reaction or a hydrogen reduction reaction on the surface of the substrate to form a vapor phase growth film. A gas generated by the reaction or a gas not used in the reaction is discharged to the outside through an exhaust port provided in the reaction chamber. After the epitaxial film is formed on the substrate, the substrate is unloaded from the reaction chamber. Next, a new substrate is carried into the reaction chamber, and an epitaxial film is formed in the same manner.

  When vapor phase growth is performed in the reaction chamber, a thin film resulting from the reaction gas is formed not only on the surface of the substrate but also on the surface of the susceptor supporting the substrate. When a vapor phase growth reaction is performed on the substrate newly carried into the reaction chamber, a further thin film is likely to be formed on the thin film. If this is repeated, the thin film formed on the susceptor results in a state where the substrate is adhered to the susceptor, which hinders the substrate from being taken out of the reaction chamber after the epitaxial film is formed.

  Therefore, the thin film formed on the susceptor is removed by etching. Such etching is performed every time when one vapor phase growth reaction is completed or every time a predetermined number of vapor phase growth reactions are completed, and the thin film formed on the susceptor is completely removed each time. For this reason, there is a problem that the time required for etching becomes longer and the time required for the manufacturing process of the epitaxial substrate becomes longer.

  For this reason, Patent Document 1 discloses an apparatus including an etching chamber for removing a thin film formed on a susceptor when forming a Si (silicon) epitaxial film. However, in this case, since an etching chamber is required separately from the reaction chamber, the apparatus becomes large.

  On the other hand, if the thin film formed on the susceptor is not completely removed in the etching process, the thin film may be peeled off in a subsequent process, resulting in a decrease in yield or warping of the substrate. When the substrate is heated to a predetermined temperature and the temperature is controlled on the susceptor, the temperature of the susceptor is generally the radiation temperature of the radiated light transmitted from the susceptor through the transmission window of the reaction chamber. It is grasped by measuring with. However, if the thin film is present on the susceptor, the measurement result may fluctuate, and accurate temperature measurement may not be possible.

JP 2007-73628 A

  The present invention has been made in view of these problems. That is, an object of the present invention is a method for processing a thin film formed in the course of a film forming process, which does not require processing in an etching chamber different from the reaction chamber, and is achieved by processing such a thin film. An object of the present invention is to provide a method capable of suppressing an increase in the time required for the entire film treatment.

  Other objects and advantages of the present invention will become apparent from the following description.

The present invention includes a first step of placing a substrate on a counterbore portion of a susceptor disposed in a reaction chamber and introducing a reaction gas into the reaction chamber to form a predetermined film on the substrate;
While the etching gas is introduced into the reaction chamber and the susceptor from which the substrate has been removed is rotated, the etching gas flows down from above the susceptor, and the reaction gas formed at the stepped portion from the countersink portion of the susceptor to the peripheral portion thereof. A second step of removing the thin film caused by
A third step of introducing an etching gas into the reaction chamber and removing a thin film caused by the reaction gas formed on the susceptor;
The present invention relates to a thin film processing method characterized by performing a third step after repeating a first step and a second step.

  In the present invention, it is preferable to perform the third step after the first step and the second step are repeated, and when the thickness of the thin film formed on the peripheral portion becomes equal to or greater than a predetermined value.

  In the present invention, it is preferable that the temperature of the susceptor is measured with a radiation thermometer provided outside the reaction chamber, and the second step is terminated when the luminance temperature of the radiated light from the boundary between the peripheral edge and the step changes. .

In the present invention, when the predetermined film is a SiC film, the etching gas preferably contains ClF ₃ gas.

  In the present invention, when the predetermined film is a Si film, the etching gas preferably contains HCl gas.

  ADVANTAGE OF THE INVENTION According to this invention, the processing method which does not need to process the thin film formed in the process of a film-forming process in the etching chamber different from a reaction chamber is provided. In addition, according to the present invention, it is possible to suppress an increase in the time required for the entire film forming process.

1 is an example of a schematic cross-sectional view of a film forming apparatus that can be used in the present embodiment. (A)-(g) is explanatory drawing of the thin film processing method in this Embodiment. (A)-(c) is explanatory drawing of the thin film processing method used as a problem.

  FIG. 1 is an example of a schematic cross-sectional view of a film forming apparatus that can be used in this embodiment. In this figure, components other than those necessary for explanation are omitted. Also, the scale is changed from the original scale so that each component can be clearly seen.

  As shown in FIG. 1, the film forming apparatus 100 has a chamber 1 as a reaction chamber. The chamber 1 has a structure in which a bell jar 102 is disposed on a base plate 101. On the base plate 101, a base plate cover 103 having a shape and a size covering the entire surface of the base plate 101 is detachably installed. The base plate cover 103 can be made of, for example, quartz. The base plate 101 and the bell jar 102 are connected by a flange 10, and the flange 10 is sealed with a packing 11. The base plate can be made of, for example, SUS (Steel Use Stainless).

  During the vapor phase growth reaction, the temperature in the chamber 1 becomes extremely high. Therefore, for the purpose of cooling the chamber 1, a cooling water flow path 3 is provided inside the base plate 101 and the bell jar 102.

  The bell jar 102 is provided with a supply port 5 for introducing the reaction gas 4. On the other hand, the base plate 101 is provided with an exhaust port 6, and after the reaction or unreacted reaction gas 4 is exhausted to the outside of the chamber 1 through the exhaust port 6.

  The exhaust port 6 is connected to the pipe 12 by a flange 13. The flange 13 is sealed with a packing 14. The packing 11 and the packing 14 are made of fluorine rubber having a heat resistant temperature of about 300 ° C.

  Inside the chamber 1, a hollow cylindrical liner 2 is arranged. The liner 2 is provided for the purpose of partitioning the inner wall 1a of the chamber 1 and the space A in which the vapor phase growth reaction on the substrate 7 is performed. Thereby, it is possible to prevent the inner wall 1a of the chamber 1 from being corroded by the reaction gas 4. Since the vapor phase growth reaction is performed at a high temperature, the liner 2 is made of a material having high heat resistance. For example, a SiC member or a member formed by coating SiC on carbon can be used.

  In the present embodiment, for convenience, the liner 2 is divided into two parts, a body part 2a and a head part 2b. The body part 2a is a part in which the susceptor 8 is disposed, and the head part 2b is a part having an inner diameter smaller than that of the body part 2a. The trunk portion 2a and the head portion 2b integrally constitute the liner 2, and the head portion 2b is located above the trunk portion 2a.

  A shower plate 15 is provided in the upper opening of the head 2b. The shower plate 15 functions as a gas rectifying plate that uniformly supplies the reaction gas 4 to the surface of the substrate 7. For this reason, the shower plate 15 is provided with a plurality of through holes 15a, and the reaction gas 4 introduced from the supply port 5 into the chamber 1 flows down toward the substrate 7 through the through holes 15a. Here, it is preferable that the reaction gas 4 efficiently reaches the surface of the substrate 7 without vainly diffusing. Therefore, the inner diameter of the head 2b is designed to be smaller than that of the body 2a. Specifically, the inner diameter of the head 2 b is determined in consideration of the position of the through hole 15 a and the size of the substrate 7.

  Further, a susceptor 8 that supports the substrate 7 is disposed inside the chamber 1, specifically, in the body 2 a of the liner 2. The susceptor 8 is made of a high heat resistant material. For example, when SiC is epitaxially grown on the substrate 7, the substrate 7 needs to have a high temperature of 1500 ° C. or higher. For this reason, for example, a surface of isotropic graphite coated with SiC by a CVD (Chemical Vapor Deposition) method is used for the susceptor 8.

  For example, the susceptor 8 may have a structure in which the substrate 7 is received in a spot facing portion 8a provided on the inner peripheral side thereof. Even after the substrate 7 is removed from the susceptor 8, it is preferable to have a structure in which the space A and the inside of the rotating cylinder 17 are separated by the counterbore portion 8 a. The counterbore part 8a may be integrated with the peripheral part to constitute the susceptor 8, and the counterbore part 8a and the peripheral part are separated from each other, and the susceptor 8 is configured by combining them. It may be.

  The substrate 7 is heated by a heater 9 disposed inside the rotary cylinder 17. The heater 9 can be a resistance heating type heater, and includes a disc-shaped in-heater 9a and an annular out-heater 9b. The in-heater 9 a is disposed at a position corresponding to the substrate 7. The outheater 9 b is disposed above the inheater 9 a and at a position corresponding to the outer peripheral portion of the substrate 7. Since the temperature of the outer peripheral portion of the substrate 7 is likely to be lower than that of the central portion, the temperature decrease of the outer peripheral portion can be prevented by providing the outheater 9b.

  The in-heater 9a and the out-heater 9b are supported by a conductive booth bar 20 having an arm shape. The booth bar 20 is configured by a member formed by coating carbon with SiC, for example. The booth bar 20 is supported by a quartz heater base 21 on the side opposite to the side supporting the in-heater 9a and the out-heater 9b. Then, the booth bar 20 and the electrode bar 23 are connected by the conductive connecting part 22 made of a metal such as molybdenum, so that power is supplied from the electrode bar 23 to the in-heater 9a and the out-heater 9b. Specifically, electricity is supplied from the electrode rod 23 to the heating elements of these heaters, and the heating elements are heated.

  The surface temperature of the substrate 7 can be measured by the radiation thermometers 24a and 24b. In FIG. 1, a radiation thermometer 24 a is used to measure the temperature near the center of the substrate 7. On the other hand, the radiation thermometer 24 b is used to measure the temperature of the outer peripheral portion of the substrate 7. Note that the temperature of the susceptor 8 may be measured by at least one of the radiation thermometers 24a and 24b.

  The radiation thermometers 24a and 24b can be provided in the upper part of the chamber 1, as shown in FIG. In this case, by making the upper part of the bell jar 102 and the shower plate 15 made of transparent quartz, temperature measurement by the radiation thermometers 24a and 24b can be prevented from being hindered by these.

The measured temperature data is sent to a control mechanism (not shown) and can be fed back to each output control of the in-heater 9a and the out-heater 9b. As an example, when SiC epitaxial growth is performed, the set temperature of each heater can be set as follows. Thereby, it is possible to heat the board | substrate 7 to about 1650 degreeC.
Temperature of inheater 9a: 1680 ° C
Temperature of outheater 9b: 1750 ° C

  A rotating shaft 16 and a rotating cylinder 17 provided at the upper end of the rotating shaft 16 are disposed on the body 2 a of the liner 2. The susceptor 8 is attached to the rotary cylinder 17, and the susceptor 8 rotates via the rotary cylinder 17 when the rotary shaft 16 rotates. During the vapor phase growth reaction, the substrate 7 is rotated together with the rotation of the susceptor 8 by placing the substrate 7 on the susceptor 8.

  The reaction gas 4 that has passed through the shower plate 15 flows down toward the substrate 7 through the head 2b. Due to the rotation of the substrate 7, the reactive gas 4 is attracted to the substrate 7 and becomes a vertical flow in the region from the shower plate 15 to the substrate 7. The reaction gas 4 that has reached the substrate 7 flows in a substantially laminar flow in the horizontal direction without forming a turbulent flow on the surface of the substrate 7. In this way, new reaction gases 4 come into contact with the surface of the substrate 7 one after another. Then, a thermal decomposition reaction or a hydrogen reduction reaction is caused on the surface of the substrate 7 to form an epitaxial film. In the film forming apparatus 100, the distance from the outer periphery of the substrate 7 to the liner 2 is narrowed so that the flow of the reaction gas 4 on the surface of the substrate 7 becomes more uniform.

  With the above configuration, the vapor phase growth reaction can be performed while heating and rotating the substrate 7. By rotating the substrate 7, the reaction gas 4 is efficiently supplied to the entire surface of the substrate 7, and an epitaxial film with high film thickness uniformity can be formed. In addition, since new reaction gases 4 are supplied one after another, the film forming speed can be improved. Of the reaction gas 4, a gas that is not used for the vapor phase growth reaction and a gas generated by the vapor phase growth reaction are discharged from the exhaust port 6 provided in the base plate 101.

  After the epitaxial film having a predetermined thickness is formed on the substrate 7, the supply of the reaction gas 4 is terminated. Subsequently, heating by the heater 9 is stopped, and the substrate 7 waits for the temperature to drop to a predetermined temperature. Further, the gas in the chamber 1 is replaced with hydrogen gas or inert gas. Note that the supply of the carrier gas from the supply port 5 may be continued until the substrate 7 becomes a predetermined temperature or lower.

  After confirming that the substrate 7 has been cooled to a predetermined temperature by the radiation thermometers 24 a and 24 b, the substrate 7 is carried out of the chamber 1. In this case, for example, the substrate 7 can be transferred using the Bernoulli effect. For example, the holding gas is ejected radially from the vicinity of the center of the back surface of the substrate 7 toward the periphery. Then, the Bernoulli effect is generated, and the substrate 7 can be floated and held from the susceptor 8. By transferring the substrate 7 in this state to a transfer robot (not shown), the substrate 7 can be carried out of the chamber 1.

  By the way, when the substrate 7 is heated by the heater 9 to bring the substrate 7 into a high temperature state, the radiant heat from the heater 9 is transmitted not only to the substrate 7 but also to other members to raise the temperature. This is particularly noticeable in members located near high-temperature portions such as the substrate 7 and the heater 9, specifically, the susceptor 8, and when the reaction gas comes into contact with the susceptor 8, the substrate heated at high temperature. As with the surface of No. 7, a thermal decomposition reaction of the reaction gas occurs.

For example, when an SiC epitaxial film is to be formed on the surface of the substrate 7, silane (SiH ₄ ) as a Si source, propane (C ₃ H ₈ ) as a C source, hydrogen gas as a carrier gas, etc. A mixed gas prepared by containing is used. However, since the reaction gas having this composition is rich in reactivity, if it contacts a member that satisfies a certain temperature condition, it will cause a decomposition reaction even if it is not on the substrate 7. As a result, a SiC thin film derived from the reaction gas is formed on the surface of the susceptor 8. When this thin film peels, it becomes dust and causes defects in the epitaxial film formed on the substrate 7. In addition, the thin film is in a state where the substrate 7 and the susceptor 8 are adhered to each other, which hinders unloading of the substrate 7 from the chamber 1 after the formation of the epitaxial film. Therefore, it is necessary to remove the thin film by etching. In this embodiment, this operation is referred to as a thin film processing method.

  The thin film processing method according to the present embodiment will be described with reference to FIGS. These are sectional views in which the susceptor 8 and the substrate 7 are partially enlarged near the end of the substrate 7.

  FIG. 2A shows the susceptor 8 and the substrate 7 before the SiC film is formed. The susceptor 8 is configured using carbon and a SiC film covering the carbon. The substrate 7 is placed on a spot facing portion 8 a provided on the susceptor 8.

  FIG. 2B shows the susceptor 8 and the substrate 7 after the SiC film 301 is formed. As shown in these figures, the SiC film 301 is formed not only on the substrate 7 but also on the susceptor 8 by the SiC epitaxial growth process.

  FIG. 2C is a view after the substrate 7 is removed from the susceptor 8. As shown in this figure, the SiC film 301 is not formed on the counterbore portion 8a of the susceptor 8 because the substrate 7 is placed thereon. However, the SiC film 301 is formed on the peripheral edge portion 8b of the susceptor 8 or on the boundary (step difference portion 8c) between the spot facing portion 8a and the peripheral edge portion 8b.

  When a new substrate 7 is placed on the susceptor 8 in the state of FIG. 2C and an epitaxial film is formed, an SiC 301 film is further formed on the already formed SiC film 301. When this process is repeated, the substrate 7 and the susceptor 8 are particularly bonded by the SiC film 301 formed in the stepped portion 8c, and hindering when the substrate 7 is carried out of the chamber 1 after the epitaxial film is formed. It becomes. For example, in the above-described method for carrying out the substrate 7, the substrate 7 and the susceptor 8 may be formed of the SiC film even if the holding gas is ejected radially from the vicinity of the center of the back surface of the substrate 7 toward the peripheral portion. By bonding with 301, the substrate 7 cannot be lifted from the susceptor 8.

  For this reason, it is necessary to remove the SiC film 301 formed on the susceptor 8. However, every time when one vapor phase growth reaction is completed or every time a predetermined number of vapor phase growth reactions are completed, it takes a long time to completely remove the SiC film 301 formed on the susceptor 8. It will be. On the other hand, when the SiC film 301 is not completely removed, according to the study by the present inventor, it has been found that the following problem occurs depending on the remaining portion.

  FIG. 3A shows a state in which the SiC film 301 formed on the susceptor 8 is not completely removed in the etching process, and the SiC film 301 is peeled off in the subsequent process. The peeled film causes a decrease in the production yield of the SiC epitaxial substrate.

  FIG. 3B is an example in which the SiC film 301 remains on the outer peripheral portion of the peripheral edge portion 8 b of the susceptor 8. In this case, the susceptor 8 is likely to be warped, and it becomes difficult to place the substrate 7 on the susceptor 8 at a predetermined position.

  Furthermore, when the constituent members of the susceptor 8 and the epitaxial film are different, there are the following problems. FIG. 3C shows an example in which a Si epitaxial film is formed on the substrate, in which the Si film 302 formed on the peripheral edge 8b of the susceptor 8 is partially removed. In this case, a problem occurs when the temperature of the susceptor 8 is measured by the radiation thermometer. That is, the temperature of the susceptor 8 can be grasped by measuring the luminance temperature of the radiated light from the peripheral portion 8b with a radiant thermometer, but the luminance temperature of the radiated light is different between where the Si film 302 is present and where it is not. This is because the former measures the luminance temperature of the radiated light from the Si film 302 while the latter measures the luminance temperature of the SiC film constituting the susceptor 8. For this reason, even if the measurement location is the same, if the portion from which the SiC film 301 is removed is not determined, there may or may not be the SiC film 301 at the measurement location, and the measurement result varies. Accurate temperature measurement is not possible.

  By the way, the SiC film 301 formed on the step portion 8 c is the most problematic among the SiC films 301 formed on the susceptor 8. This is because the substrate 7 is bonded to the susceptor 8 by the SiC film 301 in the stepped portion 8c. For this reason, the substrate 7 is hardly peeled off from the susceptor 8, which hinders the substrate 7 from being removed from the chamber 1 after the epitaxial film is formed.

  Therefore, in the present embodiment, not all of SiC film 301 formed on susceptor 8 is removed every time the removing process is performed, but only stepped portion 8c is removed. Thereby, the time required for etching SiC film 301 can be shortened. Further, since the substrate 7 is placed on the susceptor 8 in a state where the SiC film 301 is not always present at the stepped portion 8c, it is possible to prevent the substrate 7 from sticking to the susceptor 8.

  In this case, the SiC film 301 remains on the peripheral edge portion 8b of the susceptor 8, but after the etching of only the stepped portion 8c is repeated a predetermined number of times (for example, 4 to 5 times), or the remaining SiC film 301 is left. If the SiC film 301 on the susceptor 8 is completely removed after reaching the predetermined film thickness, it is possible to suppress a decrease in yield due to peeling of the remaining SiC film 301.

  Further, since the peripheral portion 8b is either in a state where the entire peripheral portion 8b is covered with the SiC film 301 or in a state where there is no SiC film 301, warping due to the SiC film 301 occurs in the susceptor 8. Can also be reduced.

  Further, when the constituent member of the susceptor 8 is different from the epitaxial film, the following effects can be obtained. For example, when the Si epitaxial film is formed on the substrate, the peripheral portion 8b is either entirely covered with the Si film or no Si film at all, and it is known in advance which is the case. be able to. That is, when only the stepped portion 8c is etched, the peripheral portion 8b is covered with the Si film, so that the brightness temperature of the emitted light is that of the Si film. On the other hand, after the etching of only the stepped portion 8c is repeated a predetermined number of times, or after the remaining Si film reaches a predetermined thickness, when all the Si film on the susceptor 8 is completely removed, In this case, there is no Si film and the surface of the susceptor 8 is exposed. In this case, the brightness temperature of the emitted light is that of the SiC film. Since it can be grasped in advance which state, the temperature of the susceptor 8 can be accurately measured by setting according to the state.

  In the present embodiment, the etching of only the stepped portion 8c of the susceptor 8 can be performed as follows.

As an etching gas, ClF ₃ gas is preferably used. When ClF ₃ gas is supplied to the chamber 1, it reacts with SiC according to the following formula (1) (Y. Miura, H. Habuka, Y. Katsumi, S. Oda, Y. Fukai, K. Fukae, T. Kato, H. Okumura, K. Arai, Japan Journal of Applied Physics. Vol. 46, No. 12, 2007, pp. 7875-7879). By this reaction, the SiC film 301 attached to the susceptor 8 is removed by etching.

3SiC + 8ClF ₃ → 3SiF ₄ + 3CF ₄ + 4Cl ₂ (1)

Further, since etching of SiC with ClF ₃ gas proceeds at a high temperature, the susceptor 8 is heated by the heater 9 at the time of etching. The heating temperature can be set to 400 ° C. or higher, for example.

When forming an Si epitaxial film, a 50% concentration HCl gas diluted with H ₂ gas can be used to remove the Si film formed on the susceptor 8. When the Si film reacts with HCl gas, a Si _x Cl _y compound is formed. This Si _x Cl _y compound is taken through the flow of the etching gas and discharged through the exhaust port 6 due to the rotation of the susceptor 8.

  The etching gas is supplied into the chamber 1 from the supply port 5 of FIG. At this time, the susceptor 8 is rotated. The etching gas flows down toward the susceptor 8, but as the susceptor 8 rotates, the etching gas first reaches the center of the susceptor 8 and then moves toward the periphery of the susceptor 8. Etching proceeds according to the movement of this gas, so that the SiC film 301 initially formed on the stepped portion 8c is etched by the gas directed toward the peripheral portion. Since the etching of the SiC film 301 formed on the peripheral edge portion 8b proceeds thereafter, if the etching is finished before the etching of the peripheral edge portion 8b proceeds, it is possible to etch only the stepped portion 8c.

  The end of etching can be managed by time, for example. In addition, when epitaxial growth of the Si film instead of the SiC film is performed, the end of etching can be grasped by measuring the temperature near the boundary between the peripheral portion 8b and the stepped portion 8c of the susceptor 8 with a radiation thermometer. . When the Si film formed on the peripheral edge 8b is etched and the underlying susceptor 8 is exposed, the luminance temperature of the emitted light changes from that of the Si film to that of the SiC film. Therefore, by examining this change, the end of etching of the step portion 8c can be found.

  When the etching of the stepped portion 8c is finished, the susceptor 8 is in a state as shown in FIG. That is, there is no SiC film 301 in the stepped portion 8c, and the SiC film 301 is formed over the entire peripheral portion 8b. In this state, as shown in FIG. 2 (f), the substrate 7 on which an epitaxial film is to be formed next is placed on the susceptor 8. The absence of the SiC film 301 in the stepped portion 8c can prevent the substrate 7 and the susceptor 8 from adhering.

  Thereafter, the steps described in FIGS. 2B to 2F are repeated. As these steps are repeated, the thickness of the SiC film 301 formed on the peripheral edge 8b of the susceptor 8 increases. Therefore, every time etching is performed a predetermined number of times (for example, 4 to 5 times), or whenever the film thickness of the SiC film 301 on the peripheral edge 8b exceeds a predetermined value, the SiC film 301 on the susceptor 8 is used. Is completely removed. Etching can be performed in the same manner as the etching of the stepped portion 8c, but it is also possible to perform etching without rotating the susceptor 8.

  When the SiC film 301 on the susceptor 8 is etched without being limited to the stepped portion 8b, the susceptor 8 is in the state shown in FIG. Thereafter, as shown in FIG. 2A, a substrate 7 on which an epitaxial film is newly formed is placed on the susceptor 8, and the steps of FIGS. 2B to 2F are repeated.

  As described above, in the thin film processing method of the present embodiment, first, the thin film formed on the susceptor is partially removed after the epitaxial reaction is completed. Next, an epitaxial reaction is performed again. After repeating this process a predetermined number of times, all the thin film on the susceptor is removed. Thereafter, the process of partially removing the thin film is repeated again after the epitaxial reaction is completed. Next, all the thin film on the susceptor is removed. By repeating the above steps, the time required for removing the thin film can be shortened. Moreover, since the process of removing all the thin films is performed after repeating the partial removal process a predetermined number of times, it is possible to suppress the remaining thin film from being peeled and the yield of the epitaxial film from being lowered. Further, since this thin film processing is performed in a reaction chamber that performs an epitaxial reaction, it is not necessary to provide an etching chamber for thin film processing separately from the reaction chamber.

  Moreover, the thin film processing method of this Embodiment can also be performed as follows. First, the thin film formed on the susceptor after the epitaxial reaction is partially removed. Next, an epitaxial reaction is performed again. After the film thickness of the thin film that has not been removed reaches a predetermined value, the entire thin film on the susceptor is removed. Thereafter, the process of partially removing the thin film is repeated again after the epitaxial reaction is completed. After the film thickness of the remaining thin film reaches a predetermined value, all the thin film on the susceptor is removed. By repeating the above steps, the time required for removing the thin film can be shortened. Moreover, if the film thickness at which the remaining thin film is easily peeled off can be known in advance, the yield of the epitaxial film is reduced by performing the process of removing all the thin film when this film thickness is reached. Can be suppressed. Further, since this thin film processing is performed in a reaction chamber that performs an epitaxial reaction, it is not necessary to provide an etching chamber for thin film processing separately from the reaction chamber.

  The partial thin film is preferably removed at a portion where the substrate is likely to stick to the susceptor by the thin film, specifically, at the boundary (step portion) between the counterbore portion of the susceptor and the peripheral portion thereof. This prevents the substrate from sticking to the susceptor and facilitates carrying the substrate out of the reaction chamber after completing the epitaxial reaction.

  Etching to the stepped portion is performed by introducing an etching gas while rotating the susceptor. Due to the rotation of the susceptor, the etching gas first reaches the central portion of the susceptor and then moves toward the peripheral portion of the susceptor. Etching proceeds according to the movement of this gas, so that the thin film initially formed in the stepped portion is etched by the gas toward the peripheral portion. Therefore, if the etching is finished before the etching of the thin film formed on the peripheral edge of the spot facing portion proceeds, it is possible to etch only the stepped portion.

  Next, an example of a film forming method using the thin film processing method in the present embodiment will be described with reference to FIGS.

  The film forming apparatus 100 of the present embodiment is suitable for forming a SiC epitaxial growth film, for example. Therefore, in the following, the formation of a SiC epitaxial film is taken as an example.

As the substrate 7, for example, a SiC wafer can be used. However, the present invention is not limited to this, and a wafer made of another material may be used depending on the case. For example, another insulating substrate such as a Si wafer, SiO ₂ (quartz), a semi-insulating substrate such as high-resistance GaAs, or the like can be used.

As the reaction gas 4, for example, propane (C ₃ H ₈ ), silane (SiH ₄ ), and hydrogen gas as a carrier gas can be used. In this case, disilane (SiH ₆ ), monochlorosilane (SiH ₃ Cl), dichlorosilane (SiH ₂ Cl ₂ ), trichlorosilane (SiHCl ₃ ), tetrachlorosilane (SiCl ₄ ), or the like may be used instead of silane. Is possible.

  First, the substrate 7 is placed on the susceptor 8. The state at this time is as shown in FIG.

  Next, the substrate 7 is rotated while the inside of the chamber 1 is at a normal pressure or an appropriate reduced pressure. The susceptor 8 on which the substrate 7 is placed is disposed at the upper end of the rotating cylinder 17. Therefore, when the rotating cylinder 17 is rotated through the rotating shaft 16, the susceptor 8 is rotated and the substrate 7 is also rotated at the same time. The number of rotations can be about 50 rpm, for example.

  Next, the substrate 7 is heated by the heater 9. In SiC epitaxial growth, the substrate 7 is heated to a predetermined temperature between 1500 ° C. and 1700 ° C., for example. Further, since the inside of the chamber 1 becomes high temperature due to the heating of the substrate 7, cooling water is supplied to the flow path 3 provided inside the base plate 101 and the bell jar 102. Thereby, it can prevent that the chamber 1 heats up excessively.

  After confirming that the temperature of the substrate 7 has reached, for example, 1650 ° C. by the radiation thermometers 24a and 24b, the rotational speed of the substrate 7 is gradually increased. For example, the rotational speed can be increased to about 900 rpm. Further, the reaction gas 4 is introduced from the supply port 5.

  The reactive gas 4 flows through the through hole 15a of the shower plate 15 and into the space A where the vapor phase growth reaction to the substrate 7 is performed. By passing through the shower plate 15, the reaction gas 4 is rectified and flows substantially vertically toward the substrate 7 that rotates below, forming a so-called vertical flow.

  The reaction gas 4 that has reached the surface of the substrate 7 causes a thermal decomposition reaction or a hydrogen reduction reaction on this surface to form a SiC epitaxial film. Excess reaction gas 4 that has not been used in the vapor phase growth reaction and gas generated by the vapor phase growth reaction are exhausted to the outside through an exhaust port 6 provided below the chamber 1.

  After the SiC film having a predetermined thickness is formed on the substrate 7, the supply of the reaction gas 4 is terminated. In this state, as shown in FIG. 2B, the SiC film 301 is formed not only on the substrate 7 but also on the susceptor 8.

  Subsequently, heating by the heater 9 is stopped, and the substrate 7 waits for the temperature to drop to a predetermined temperature. Further, the gas in the chamber 201 is replaced with hydrogen gas, inert gas, or the like. Note that the supply of the carrier gas from the supply port 5 of FIG. 1 may be continued until the substrate 7 becomes a predetermined temperature or lower.

  After confirming that the substrate 7 has been cooled to a predetermined temperature by the radiation thermometers 24 a and 24 b, the substrate 7 is carried out of the chamber 1. In this case, for example, the substrate 7 can be transferred using the Bernoulli effect. For example, the holding gas is ejected radially from the vicinity of the center of the back surface of the substrate 7 toward the periphery. Then, the Bernoulli effect is generated, and the substrate 7 can be floated and held from the susceptor 8. By transferring the substrate 7 in this state to a transfer robot (not shown), the substrate 7 can be carried out of the chamber 1.

The susceptor 8 after transferring the substrate 7 to the transfer robot is in the state shown in FIG. Therefore, the susceptor 8 is heated and rotated, and an etching gas is supplied from the supply port 5 to remove the SiC film 301 formed on the stepped portion 8c of the susceptor 8 (FIG. 2D). Since the upper opening of the rotating cylinder 17 is closed by the susceptor 8, the etching gas enters the rotating cylinder 17 and the members such as the heater 9 and the electrode rod 23 are attacked by the etching gas. There is nothing. As an etching gas, ClF ₃ gas is preferably used.

  When the etching of the stepped portion 8c is finished, the susceptor 8 is in a state as shown in FIG. That is, there is no SiC film 301 in the stepped portion 8c, and the SiC film 301 is formed over the entire peripheral portion 8b.

  After the etching gas is discharged from the inside of the chamber 1 and replaced with an inert gas or the like, the next epitaxial reaction can be performed. A new substrate 7 is carried into the chamber 1 and placed on the susceptor 8. The state at this time is as shown in FIG. Since the SiC film 301 on the stepped portion 8c is removed by the etching process, it is possible to prevent the substrate 7 and the susceptor 8 from adhering to each other.

  After placing the substrate 7 on the susceptor 8, an SiC film is formed according to the method described above. The state after the SiC film is formed corresponds to the state in which the SiC film 301 on the peripheral edge 8b is thick in FIG. This is because the SiC film 301 on the peripheral edge 8b has not been removed in the previous etching step, and a new SiC film is formed thereon.

  Thereafter, when the substrate 7 is removed from the susceptor 8, a state similar to that shown in FIG. The SiC film 301 formed on the step portion 8c is a film formed by a new epitaxial reaction. This film is removed by the same etching process as described above. Etching at this time is also performed on the stepped portion 8c, and the SiC film 301 on the peripheral portion 8b is not removed. As a result, the susceptor 8 is in the same state as in FIG. Then, as in FIG. 2F, a new substrate 7 is placed on the susceptor 8 to form a new epitaxial film.

  After repeating the etching process on the stepped portion 8c and the formation of the epitaxial film, the SiC film 301 formed on the susceptor 8 is removed without being limited to the stepped portion 8c. As a result, the susceptor 8 is in the state shown in FIG.

  Thereafter, a new substrate 7 is placed on the susceptor 8. The state at this time is as shown in FIG. Thereafter, the above steps are repeated. That is, after repeating the same process as described in FIGS. 2B to 2F, all the SiC films on the susceptor 8 are removed to obtain the state of FIG. Thereafter, the process returns to the state shown in FIG.

  By using the thin film processing method of this embodiment mode, a thin film formed in the course of a film forming process can be removed, and a decrease in yield due to peeling of the thin film can be suppressed. Since the time required for the thin film processing of the present embodiment is shorter than that of the conventional method, the time required for the entire film forming process is prevented from being increased by the thin film processing. Furthermore, since the thin film processing of this embodiment is performed in a reaction chamber that performs an epitaxial reaction, it is not necessary to provide an etching chamber for thin film processing separately from the reaction chamber.

  In addition, this invention is not limited to the said embodiment, It can implement in various deformation | transformation in the range which does not deviate from the summary of this invention. For example, in the above-described embodiment, the example in which the film is formed on the substrate while rotating the substrate has been described. However, in the present invention, the film may be formed without rotating the substrate.

  Moreover, although the epitaxial growth apparatus was mentioned as an example of the film-forming apparatus in the said embodiment and the formation of the SiC crystal film was demonstrated, it is not restricted to this. As long as the reaction gas is supplied into the reaction chamber and the substrate placed in the reaction chamber is heated to form a film on the surface of the substrate, other film forming apparatuses may be used. It can also be used to form a film.

  In addition, although descriptions of parts that are not directly required for the present invention, such as apparatus configuration and control method, are omitted, the required apparatus configuration, control method, and the like can be appropriately selected and used. .

  In addition, all film forming apparatuses and elements having various elements that can be appropriately modified by those skilled in the art are included in the scope of the present invention.

DESCRIPTION OF SYMBOLS 1 Chamber 1a Inner wall 2 Liner 2a Body 2b Head 3 Flow path 4 Reaction gas 5 Supply port 6 Exhaust port 7 Substrate 8 Susceptor 8a Counterbore part 8b Peripheral part 8c Step part 9 Heater 9a In-heater 9b Out-heater 10, 13 Flange 11 , 14 Packing 12 Piping 15 Shower plate 15a Through hole 16 Rotating shaft 17 Rotating cylinder 20 Booth bar 21 Heater base 22 Connecting portion 23 Electrode rod 24a, 24b Radiation thermometer 100 Film forming apparatus 101 Base plate 102 Belger 103 Base plate cover 301 SiC film 302 Si film

Claims (5)

A first step of placing a substrate on a counterbore of a susceptor disposed in a reaction chamber, introducing a reaction gas into the reaction chamber to form a predetermined film on the substrate;
An etching gas is introduced into the reaction chamber, and the susceptor from which the substrate has been removed is rotated, while the etching gas is caused to flow down from above the susceptor, and a stepped portion from the countersink portion of the susceptor to the peripheral portion thereof. A second step of removing a thin film caused by the reaction gas formed in
A third step of introducing an etching gas into the reaction chamber and removing a thin film caused by the reaction gas formed on the susceptor,
A thin film processing method comprising performing the third step after repeating the first step and the second step.   2. The third step is performed after the first step and the second step are repeated, and when the thickness of the thin film formed on the peripheral portion becomes a predetermined value or more. The thin film processing method as described in 2.   The temperature of the susceptor is measured with a radiation thermometer provided outside the reaction chamber, and the second step is terminated when the luminance temperature of the radiated light from the boundary between the peripheral edge and the stepped portion changes. The thin film processing method according to claim 1, wherein the thin film processing method is characterized. The thin film processing method according to claim 1, wherein the predetermined film is a SiC film, and the etching gas contains ClF ₃ gas. The thin film processing method according to claim 1, wherein the predetermined film is a Si film, and the etching gas contains HCl gas.

Images