JP4417950B2 - Film forming method and film forming apparatus - Google Patents

Description

  The present invention relates to a film forming method such as epitaxial vapor deposition, and a film forming apparatus that realizes the film forming method.

  In the manufacturing process of a semiconductor device, an epitaxial film is formed on a wafer by using a film forming apparatus such as a vertical epitaxial vapor phase growth apparatus.

  In general, in a vertical epitaxial vapor phase growth apparatus, for example, as disclosed in Japanese Patent Application Laid-Open No. 10-312966, a susceptor for mounting a plurality of wafers in a reaction chamber composed of a quartz bell jar, A plurality of gas supply nozzles are provided on the gas supply pipe passing through the center of the susceptor and supplying process gas onto the wafer. A heating means for heating the wafer and a rotating means for rotating the susceptor are installed below the susceptor, and a discharging means for discharging the gas is connected to the lower part of the film forming chamber.

  Using such a vertical epitaxial vapor phase growth apparatus, an epitaxial film is formed on the wafer. A susceptor on which a plurality of wafers are placed is rotated, and a process gas is supplied to the wafer surface from a gas supply nozzle. At this time, the process gas supplied from the gas supply nozzle passes through the susceptor and flows to the discharge means. At that time, a part of the process gas hits a quartz bell jar having a relatively low temperature and is deposited. When the amount of deposition increases, a part rises as particles and rides on the airflow in the reaction chamber and falls onto the wafer. Therefore, it is necessary to maintain the inside of the reaction chamber when a certain amount is deposited.

  Usually, a process gas is supplied from a gas supply nozzle in a fixed direction (for example, three directions every 120 °). Therefore, it accumulates in the same place of a quartz bell jar, and the amount of accumulation will vary. Actually, the maintenance cycle is determined by the maximum value of the deposition amount. Therefore, it can be expected that the maintenance cycle can be prolonged and the throughput can be improved by suppressing the dispersion of the accumulation amount.

Methods for suppressing variations in the amount of deposition in the wafer surface have been proposed in Patent Document 2 (Claim 1, FIG. 1 etc.) and Patent Document 3 (Claim 1, FIG. 1 etc.). However, this does not refer to variations in the amount of deposition on the reaction chamber wall.
Japanese Patent Laid-Open No. 10-312966 JP 2000-58463 A JP-A-8-88187

  As described above, the conventional film forming method or film forming apparatus has a problem that it is difficult to extend the maintenance cycle.

  An object of the present invention is to provide a film forming method and a film forming apparatus capable of extending the maintenance cycle of the film forming apparatus and improving the throughput.

The film formation method of one embodiment of the present invention is such that a plurality of wafers are placed on a susceptor installed in a reaction chamber, the wafers are heated, the susceptor is rotated about its center, and the susceptor center is penetrated. The gas supply nozzle is provided with three or more stages, and in each stage, the process gas is supplied from three openings provided at equal angles , and the uppermost opening of the plurality of openings is provided. From diagonally below, process gas is supplied in a phase that is equal to the opening of the lowermost stage and from a phase different from the opening of at least one stage, and the process gas supply direction from the openings provided in a plurality of stages is reacted. Fluctuating relative to the chamber.

In the film forming method of the present invention, it is desirable to rotate the gas supply nozzle .

In the film forming method of the present invention, it is preferable that the gas supply nozzle is rotated at an angle different from the phase difference of the openings provided in the plurality of stages .

In the film forming method of the present invention, it is desirable that the gas supply nozzle is rotated at a predetermined rotation speed while supplying the process gas .

  In the film forming method of the present invention, it is desirable to raise and lower the process gas supply nozzle.

A film formation apparatus of one embodiment of the present invention includes a reaction chamber for forming a film on a wafer, a susceptor for mounting a plurality of wafers, a susceptor rotation mechanism that rotates the susceptor, and a position immediately below or inside the susceptor. A heater for heating the wafer, a gas supply nozzle provided through the center of the susceptor and having an opening for supplying process gas onto the wafer, and the opening relative to the reaction chamber. A nozzle rotation mechanism for fluctuating automatically, and the gas supply nozzle has three or more stages for supplying process gas onto the wafer, and has openings provided at three equiangular positions in each stage. The opening has a protrusion for supplying a process gas having a phase equal to that of the lowermost opening and a phase different from that of the opening of at least one stage obliquely downward.

In the film forming apparatus of the present invention, it is desirable that at least one step interval of the plurality of openings is different from the other step interval .

In the film forming apparatus of the present invention, the nozzle rotation mechanism preferably includes a rotation control mechanism for controlling the rotation angle .

In the film forming apparatus of the present invention, the nozzle rotation mechanism preferably includes a rotation control mechanism for controlling the rotation angle .
The nozzle rotation mechanism preferably includes a rotation speed control mechanism for controlling the rotation speed .

  With the film forming method and film forming apparatus of the present invention, the maintenance cycle of the film forming apparatus can be prolonged and the throughput can be improved.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(Embodiment 1)
FIG. 1 is a sectional view of a vertical epitaxial vapor phase growth apparatus according to this embodiment. As shown in the figure, a susceptor 3 on which a plurality of wafers 1 can be placed is installed in a film forming chamber 2 that is a reaction chamber that is formed of a quartz bell jar and forms a film on the wafer 1.

  A gas supply pipe 4 for supplying a film forming gas is disposed from below the film forming chamber 2. A gas supply nozzle 5 is connected above the gas supply pipe 4. The gas supply nozzle 5 passes through the central portion of the susceptor 3 and has an opening for supplying a film forming gas onto the wafer 1 from above the susceptor 3.

  Below the susceptor 3, a heating means 6 such as an RF coil for heating the wafer 1 via the susceptor 3 and a rotating means 7 for rotating the susceptor 3 are installed. A discharge means 8 for discharging gas is connected to the lower part of the film forming chamber 2. Further, a nozzle rotation control mechanism 9 is provided that is connected to the gas supply pipe 4 and rotates the gas supply nozzle 5 by a predetermined angle.

  FIG. 2 shows a side view of the gas supply nozzle 5 and FIG. 3 shows a top view of the gas supply nozzle 5. As shown in the figure, openings 5a, 5b, 5c, and 5d that are formed, for example, in four stages at predetermined intervals and phases in three directions every 120 ° are provided. Only the uppermost opening 5a has a protrusion (branch) for supplying process gas obliquely downward.

Here, the gas supply direction (formation direction of the projection (branch)) is not horizontal, that is, the angle γ with the central axis of the gas supply nozzle 5 needs to be less than 90 °. When an angle between a line connecting the edge of the susceptor and the center of the uppermost opening (the base of the protrusion (branch)) and the central axis of the gas supply nozzle 5 is β,
β ≦ γ ≦ 0.3β + 63 (degrees)
It is preferable that If γ is smaller than β, it is difficult to supply the gas evenly over all the wafers 1. On the other hand, if γ is larger than (0.3β + 63), the gas flows in the direction of the wall surface of the film forming chamber 2, and it becomes difficult to efficiently supply the gas onto the wafer 1.

  Openings 5b and 5c for supplying gas in the horizontal direction are sequentially provided in the second stage of the same phase at the lower stage of the uppermost stage (first stage) and the third stage of a phase different from these. The lowermost stage (fourth stage) is provided with an opening 5d for supplying gas in the same horizontal direction in the same phase as the uppermost stage (first stage). The gas supply nozzle 5 is rotatable and can be rotated appropriately to change the process gas supply direction.

An epitaxial film is formed on the wafer 1 using such a vertical epitaxial vapor phase growth apparatus. First, for example, ten 4-inch wafers 1 are placed on the susceptor 3. A source gas such as monosilane or trichlorosilane is supplied from a gas supply means (not shown) through a gas supply pipe 4 through a gas supply nozzle 5 at a mixing ratio of 140 SLM for H ₂ gas and 10.5 SLM for trichlorosilane, for example. The process gas containing is supplied onto the wafer 1. Then, the wafer 1 is heated to, for example, 1130 ° C. by the heating means 6, the process gas is reduced or thermally decomposed, and deposited while rotating the susceptor 3. In this way, an epitaxial film is formed on the wafer 1.

  Here, the film thickness distribution of the formed epitaxial film is shown in FIG. As shown in the figure, it can be seen that there is no large variation in film thickness, and that a good film thickness distribution is obtained. A comparative example in which process gas is supplied in the horizontal direction from the uppermost opening is also shown. As shown in the figure, it can be seen that by supplying obliquely downward from the uppermost opening 5a, the film thickness variation of the formed epitaxial film is reduced and the film thickness is increased.

  FIG. 5 shows a horizontal conceptual diagram of a process gas flow during film formation, and FIG. 6 shows a vertical sectional conceptual diagram thereof. As shown in the figure, since the process gas supplied from the gas supply nozzle 5 is supplied obliquely downward from the uppermost opening 5a, the gas flow to the upper part of the film forming chamber 2 is suppressed, and the susceptor 3 Are supplied uniformly and efficiently. Therefore, as described above, the film thickness on the wafer 1 increases, and the deposit 10 cooled and deposited by the wall of the film forming chamber 2 in the gas flow direction (three directions in the present embodiment) also increases. However, it is thought that the influence cannot be ignored.

  In this manner, after an epitaxial film having a predetermined thickness is formed on the wafer 1, the film formation chamber 2 is released to the atmosphere and the wafer is unloaded. At this time, the gas supply nozzle 5 is rotated, for example, 30 ° clockwise by the nozzle rotation control mechanism 9.

  Similarly, a wafer is placed on the susceptor 3 to perform a film forming process. After the film forming process, the gas supply nozzle 5 is similarly rotated 30 ° clockwise.

  As described above, the deposition position on the quartz bell jar is horizontally adjusted by rotating the gas supply nozzle each time the film forming process is performed and changing the process gas supply direction to the film forming chamber in the horizontal circumferential direction of the film forming chamber. It is possible to make the deposited film thickness uniform and to suppress an increase in the deposited film thickness.

  In this embodiment, the gas supply nozzle is rotated 30 ° clockwise for each film forming process, but the rotation direction and rotation angle are not particularly limited. The rotation direction may be a fixed direction, and the rotation angle only needs to be different from the phase difference (120 ° in the present embodiment) of each opening of the gas supply nozzle 5.

(Embodiment 2)
FIG. 7 shows a sectional view of the vertical epitaxial vapor phase growth apparatus of this embodiment. The structure is substantially the same as that of the first embodiment, except that the nozzle rotation control mechanism 19 is provided with a rotation speed control mechanism 20.

  An epitaxial film is formed on the wafer 11 using such a vertical epitaxial vapor phase growth apparatus. First, as in the first embodiment, the wafer 11 is placed on the susceptor 13, and the process gas is supplied onto the wafer 11 from the gas supply nozzle 15. Then, the wafer 11 is heated by the heating means 16, and an epitaxial film is formed on the wafer 11 while rotating the susceptor 13 at 6 to 10 rpm. At the same time, the gas supply nozzle 15 is rotated by the nozzle rotation control mechanism 19 while the rotation speed is controlled to 0.1 rpm, for example, by the nozzle rotation control mechanism 20.

  In this way, by rotating the gas supply nozzle during the film forming process and changing the process gas supply direction to the film forming chamber in the horizontal circumferential direction, the deposition position in the quartz bell jar is changed in the horizontal direction, thereby depositing film thickness. Can be made uniform and an increase in the deposited film thickness can be suppressed.

  In this embodiment, the gas supply nozzle 15 is rotated while being controlled at 0.1 rpm, but the rotation speed of the gas supply nozzle 15 may be lower than the rotation speed of the susceptor 13. For example, it may be set to rotate once during one film forming process.

  In these embodiments, the gas supply nozzles 1 and 15 are rotated. However, the present invention is not limited to this as long as the process gas supply direction to the film forming chamber can be changed. For example, as shown in FIG. 8, the gas supply nozzle 5 of the film forming apparatus shown in FIG. 1 is connected to the nozzle lift control device 21 so as to be able to move up and down, and is driven in the vertical (vertical) direction. It may be varied in the vertical circumferential direction. In that case, the nozzle rotation control mechanism 9 is provided with a sliding mechanism in the vertical direction, so that the rotation driving and the vertical driving can be performed.

  In addition, the susceptors 3 and 13 are rotated at the time of film formation, but the temperature distribution in the wafer surface may be made uniform. For example, the heating means 6 and 16 may be rotated.

  Further, ten 4-inch wafers are placed on the susceptors 3 and 13, but the size and the number of wafers are not particularly limited, and it is possible to place a suitable number of 6-inch and 8-inch wafers. Is possible.

  Further, in the gas supply nozzles 5 and 15, the lowermost stage (fourth stage) and the uppermost stage (first stage) have the same phase, but from the lowest stage (fourth stage) that contributes most to the film formation. In order to suppress the diffusion of the supply gas by the supply gas obliquely upward from the uppermost stage (first stage), the phases of the openings 5a and 5d at the uppermost stage (first stage) and the lowermost stage (fourth stage) are Preferably they are the same. In this case, since many deposits are formed in the same place, it is more effective to change the process gas supply direction relative to the film forming chamber. Further, the intervals between these stages are not necessarily equal. As shown in FIG. 2, the intervals between the first and second stages, between the second and third stages, and between the third and fourth stages may be different, or all the intervals may be different.

  According to these embodiments, since the increase in the deposited film thickness in the film forming chamber can be suppressed, the maintenance cycle can be prolonged. In a semiconductor device formed from a wafer and a wafer through an element formation process and an element separation process, it is possible to improve throughput without reducing yield and stability of element characteristics. In particular, a thick film formation process of a power semiconductor device such as a power MOSFET or IGBT (insulated gate bipolar transistor) in which a thick film of about several tens to 100 μm is used for an N-type base region, a P-type base region, an insulating isolation region, and the like. By applying to the above, the process cost can be greatly reduced.

In addition, this invention is not limited to embodiment mentioned above. For example, although the case where an epitaxial film is formed on a Si substrate has been described in the present embodiment, the present invention can be applied to the formation of a poly-Si layer, and can be applied to other compound semiconductors such as a GaAs layer, GaAlAs, InGaAs, and the like. Further, the present invention can be applied to the case of forming a SiO ₂ film or a Si ₃ N ₄ film. In the case of a SiO ₂ film, in addition to monosilane (SiH ₄ ), N ₂ , O ₂ , and Ar gas are used as the Si ₃ N ₄ film. In this case, NH ₃ , N ₂ , O ₂ , Ar gas and the like are supplied in addition to monosilane (SiH ₄ ). Various other modifications can be made without departing from the scope of the invention.

  In addition, this invention is not limited to embodiment mentioned above. Various other modifications can be made without departing from the scope of the invention.

1 is a cross-sectional view of a vertical epitaxial vapor phase growth apparatus according to one embodiment of the present invention. The side view of the gas supply nozzle 5 shown in FIG. FIG. 2 is a top view of the gas supply nozzle 5 shown in FIG. The figure which shows the film thickness distribution of the epitaxial film formed using the film-forming apparatus shown in FIG. FIG. 5 is a conceptual top view of a process gas flow during film formation according to one embodiment of the present invention. FIG. 6 is a conceptual cross-sectional view of a process gas flow during film formation according to one embodiment of the present invention. 1 is a cross-sectional view of a vertical epitaxial vapor phase growth apparatus according to one embodiment of the present invention. 1 is a cross-sectional view of a vertical epitaxial vapor phase growth apparatus according to one embodiment of the present invention.

Explanation of symbols

1, 11 Wafer 2, 12 Deposition chamber 3, 13 Susceptor 4, 14 Gas supply pipe 5, 15 Gas supply nozzle 6, 16 Heating means 7, 17 Rotating means 8, 18 Discharge means 9, 19 Nozzle rotation control mechanism 10 Deposition 20 Rotational speed control mechanism

Claims (10)

Place multiple wafers on a susceptor installed in the reaction chamber,
Heating the wafer;
Rotating the susceptor around its center,
The gas supply nozzle installed so as to penetrate the center of the susceptor has three or more stages. In each stage, the process gas is supplied from three openings provided at equal angles , and the plurality of stages are provided. Among the openings, from the uppermost opening , the process gas is supplied obliquely downward, with the same phase as the lowermost opening, and with a phase different from the opening of at least one stage ,
A film forming method, wherein the process gas supply direction from each of the openings is changed relative to the reaction chamber. The film forming method according to claim 1, wherein the gas supply nozzle is rotated . The film forming method according to claim 2, wherein the gas supply nozzle is rotated at an angle different from a phase difference of the openings provided in the plurality of stages . The film forming method according to claim 2 , wherein the gas supply nozzle is rotated at a predetermined rotation speed while supplying the process gas . The film deposition method according to any one of claims 1 to 4, characterized in that elevating the process gas supply nozzle. A reaction chamber for film formation on the wafer;
A susceptor for mounting a plurality of the wafers;
A susceptor rotation mechanism for rotating the susceptor;
A heater provided directly below or inside the susceptor for heating the wafer;
A gas supply nozzle provided through the center of the susceptor and having an opening for supplying process gas onto the wafer;
A nozzle rotation mechanism for changing the opening relative to the reaction chamber;
The gas supply nozzle has three or more stages for supplying the process gas onto the wafer, and has openings provided at three positions at equal angles in each stage .
The uppermost opening has a protrusion for supplying the process gas having a phase equal to that of the lowermost opening and a phase different from that of at least one of the openings , obliquely downward. apparatus. The film forming apparatus according to claim 6 , wherein an interval between each of the plurality of openings is different from an interval between at least one of the other steps. The film forming apparatus according to claim 6 , wherein the nozzle rotation mechanism includes a rotation control mechanism for controlling a rotation angle . The nozzle rotating mechanism, film-forming apparatus according to claim 6 or claim 7, characterized that you provided with rotational speed control mechanism for controlling the rotational speed. Film forming apparatus according to any one of claims 9 claims 6, characterized in that it comprises a lifting control mechanism for raising and lowering said gas supply nozzle.

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