JP6052070B2 - Epitaxial wafer manufacturing method and manufacturing apparatus thereof - Google Patents

Description

  The present invention relates to a method for manufacturing an epitaxial wafer by growing an epitaxial film on a semiconductor wafer such as a silicon wafer, and an apparatus for manufacturing the epitaxial wafer.

  Conventionally, there is an epitaxial growth method in which a single crystal substrate is disposed in a reaction chamber having at least a downwardly convex upper wall, a source gas and a carrier gas are introduced into the reaction chamber from a gas inlet, and an epitaxial layer is stacked on the single crystal substrate. (For example, refer to Patent Document 1). In this epitaxial growth method, depending on the flow rate of the carrier gas introduced from the gas inlet into the reaction chamber, the radius of curvature of the upper wall of the reaction chamber or the height direction between the upper end of the gas inlet and the lower end of the upper wall of the reaction chamber After adjusting either or both of the differences in the above, an epitaxial layer is stacked on the single crystal substrate. When the flow rate of the carrier gas introduced from the gas inlet into the reaction chamber exceeds 70 slm, the curvature radius of the upper wall of the reaction chamber is adjusted to 4500 mm or more and less than 7500 mm, or the upper end of the gas inlet and the upper wall of the reaction chamber are The difference in the height direction from the lower end is adjusted to 0 mm or more and 2 mm or less, or the curvature radius and the difference are adjusted to the above ranges, respectively. Further, when the flow rate of the carrier gas introduced from the gas inlet into the reaction chamber is less than 60 slm, the curvature radius of the upper wall of the reaction chamber is adjusted to be greater than 3000 mm and less than 4500 mm, or the upper end of the gas inlet and the top of the reaction chamber The height difference with the lower end of the wall is adjusted to 2.5 mm or more, or the radius of curvature and the difference are adjusted to the above ranges, respectively.

  In the epitaxial growth method configured as described above, the radius of curvature of the upper wall of the reaction chamber, or the upper end of the gas inlet and the lower end of the upper wall of the reaction chamber, depending on the flow rate of the carrier gas introduced from the gas inlet into the reaction chamber. Since the epitaxial layer is stacked on the single crystal substrate after adjusting one or both of the differences in the height direction, the productivity or back surface quality provided by the carrier gas at each flow rate can be improved and uniform. An excellent epitaxial layer having a uniform thickness distribution can be stacked. In the present specification, the unit “slm” is an abbreviation of “standard liter / minute” and refers to a flow rate per minute at a pressure of 0.1 MPa (1 atm) and a temperature of 0 ° C.

JP 2009-147105 A (Claims 1, 5 and 6, paragraph [0014], FIG. 1)

  However, in the conventional epitaxial growth method disclosed in Patent Document 1, the curvature radius of the upper wall of the reaction chamber and the upper end of the gas introduction port react with the flow rate of the carrier gas introduced from the gas introduction port into the reaction chamber. The difference in the height direction from the lower end of the upper wall of the chamber must be changed, that is, when the flow rate of the carrier gas is changed from over 70 slm to less than 60 slm, or the flow rate of the carrier gas is less than 60 slm When changing from the above state to a state exceeding 70 slm, the appropriate downward convex shape is formed each time according to the flow rate of the supply gas from among the plurality of upper walls having different downward convex curvature radii. Therefore, it is difficult to apply to actual production. Further, in the epitaxial growth method disclosed in the above-mentioned conventional patent document 1, the upper wall has a lower convex upper dome, and an upper dome flange that is welded in a state of being fitted into the upper dome and holds the upper dome. Between the lower surface of the flange and the upper end of the gas inlet, there is an upper liner that constitutes the upper edge of the gas inlet and a base member that fixes the upper dome flange. Therefore, if the difference in height between the upper end of the gas inlet and the lower end (lowermost surface) of the upper dome is set to 0 mm or more and 2 mm or less, the lowermost surface of the upper dome is positioned below the extended surface of the lower surface of the upper dome flange. Therefore, if the upper dome is welded to the upper dome flange and placed on a flat plate such as a storage shelf or a dryer with the upper dome protruding downward, the lower surface of the upper dome will contact the lower surface before the lower surface of the upper dome flange contacts the flat plate. May come into contact with the flat plate, damaging the lowermost surface of the upper dome, and there is a problem that the handling of the upper dome with the flange for the upper dome is troublesome.

  As a result of intensive studies in view of the above problems, the present inventors have used an upper dome having a radius of curvature within a specific range, and set the distance between the lowermost surface of the upper dome and the extended surface of the lower surface of the upper dome flange to a specific range. In this case, the inventors have found that a uniform thickness distribution of the epitaxial film can be obtained in the plane regardless of the flow rate of the gas supplied into the apparatus, and the present invention has been completed.

  The first object of the present invention is to grow an epitaxial film on a semiconductor wafer with a uniform thickness without changing the upper dome even if the gas flow rate supplied from the gas inlet into the reaction vessel is changed. An object of the present invention is to provide an epitaxial wafer manufacturing method and a manufacturing apparatus thereof. The second object of the present invention is to place the uppermost dome of the upper dome above the extended surface of the lower surface of the upper dome flange, so that the upper dome with the upper dome flange can be projected even on a flat plate with a downward projection. Since the lowermost surface of the upper dome does not contact the flat plate before the lower surface of the upper surface contacts the flat plate, and the lowermost surface of the upper dome is not damaged, the upper dome with the flange for the upper dome can be handled as a part relatively easily. It is to provide a manufacturing method and a manufacturing apparatus thereof.

  According to a first aspect of the present invention, a susceptor on which a semiconductor wafer can be placed is provided in a reaction vessel having an upper dome whose center bulges downward and an upper dome flange for holding the upper dome, and the semiconductor wafer is placed on the susceptor. In the mounted state, the source gas and the carrier gas are introduced into the reaction vessel from the gas inlet located below the upper dome flange to grow an epitaxial film on the semiconductor wafer, and located below the upper dome flange. In the method of manufacturing an epitaxial wafer in which excess gas is discharged from the gas discharge port, the lowermost surface of the upper dome is configured to be positioned above the extended surface of the lower surface of the upper dome flange, and the curvature radius of the upper dome is 4500 to 6000 mm. Set within the range, the bottom surface of the upper dome and the upper And setting the distance between the lower surface of the extended surface of the over arm flange within the 1.0～3.5Mm. In this specification, setting the radius of curvature of the upper dome within the range of 4500 to 6000 mm means forming the upper dome so that the radius of curvature of the upper dome is within the range of 4500 to 6000 mm. Further, in this specification, when the distance between the lowermost surface of the upper dome and the extended surface of the lower surface of the upper dome flange is set within a range of 1.0 to 3.5 mm, the distance between the lowermost surface of the upper dome and the lower surface of the upper dome flange is The upper dome is formed so that the distance to the extended surface is within a range of 1.0 to 3.5 mm.

  According to a second aspect of the present invention, there is provided a reaction vessel having an upper dome whose center bulges downward and an upper dome flange for holding the upper dome, a susceptor provided in the reaction vessel and capable of mounting a semiconductor wafer, A gas inlet located below the upper dome flange for introducing the source gas and carrier gas into the reaction vessel, and a gas facing the gas inlet and positioned below the upper dome flange for discharging the source gas and carrier gas In an epitaxial wafer manufacturing apparatus having a discharge port, the lowermost surface of the upper dome is configured to be located above the extended surface of the lower surface of the upper dome flange, and the curvature radius of the upper dome is set within a range of 4500 to 6000 mm. The uppermost surface of the upper dome and the extended surface of the lower surface of the flange for the upper dome Away it is characterized in that it is set in the range of 1.0～3.5Mm. In the present specification, setting the radius of curvature of the upper dome within the range of 4500 to 6000 mm means that the upper dome is formed such that the radius of curvature of the upper dome is within the range of 4500 to 6000 mm. In the present specification, the distance between the lowermost surface of the upper dome and the extended surface of the lower surface of the upper dome flange is set within a range of 1.0 to 3.5 mm. The upper dome is formed so that the distance to the extended surface of the lower surface is within the range of 1.0 to 3.5 mm.

  According to the epitaxial wafer manufacturing method and the manufacturing apparatus of the first and second aspects of the present invention, the curvature radius of the lowermost surface of the upper dome and the upper dome maximum depending on the gas flow rate supplied from the gas inlet into the reaction vessel. An epitaxial film can be grown on the semiconductor wafer with a uniform thickness without replacing the lower dome with the upper dome whose distance from the extended surface of the lower surface of the upper dome flange is changed.

  Further, by positioning the lowermost surface of the upper dome above the extended surface of the lower surface of the upper dome flange, the lower surface of the upper dome flange comes into contact with the flat plate even when the upper dome with the upper dome flange is on the flat plate in a downwardly convex state. Since the lowermost surface of the upper dome does not contact the flat plate before and does not damage the lowermost surface of the upper dome, the upper dome with the upper dome flange can be handled as a part relatively easily.

It is a longitudinal section lineblock diagram showing a manufacturing device of an epitaxial wafer of an embodiment of the present invention. It is a top view of the silicon wafer which shows the state where the gas which flows on the upper surface of the silicon wafer placed on the susceptor of the apparatus changes depending on the radius of curvature and the position of the upper dome. It is a top view of the silicon wafer which shows the measurement range of the thickness of the epitaxial film grown on the silicon wafer upper surface. The silicon wafers of Examples 1 to 9 and Comparative Examples 1 to 6 were epitaxial when the hydrogen flow rate was changed with the distance H between the uppermost lower surface of the upper dome and the extended surface of the lower surface of the upper dome flange fixed to 1.0 mm. It is a figure which shows the change of the largest thickness dispersion | variation ((L3 / te) * 100) of a film | membrane. The silicon wafers of Examples 10 to 18 and Comparative Examples 7 to 12 are epitaxial when the hydrogen flow rate is changed with the distance H between the lowermost surface of the upper dome and the extended surface of the lower surface of the upper dome flange fixed to 3.5 mm. It is a figure which shows the change of the largest thickness dispersion | variation ((L3 / te) * 100) of a film | membrane. For the silicon wafers of Comparative Examples 13 to 27, with the distance H between the lowermost surface of the upper dome and the extended surface of the lower surface of the upper dome flange fixed to 0 mm, the maximum thickness variation ((L3 / Te) × 100). For the silicon wafers of Comparative Examples 28 to 42, the maximum thickness variation of the epitaxial film when the hydrogen flow rate was changed with the distance H between the lowermost surface of the upper dome and the extended surface of the lower surface of the upper dome flange fixed to 5.0 mm ( It is a figure which shows the change of (L3 / te) * 100).

  Next, an embodiment for carrying out the present invention will be described with reference to the drawings. FIG. 1 is an apparatus cross-sectional view schematically showing a single wafer epitaxial growth apparatus (Applied Materials, Inc .: Centura (registered trademark)) generally used for manufacturing an epitaxial wafer having a diameter of 300 mm. The epitaxial wafer manufacturing apparatus 10 is an apparatus for growing an epitaxial layer on the surface of a silicon wafer 11, and is a reaction vessel 12 and a disk-like plate provided in the reaction vessel 12 on which the silicon wafer 11 can be placed. Susceptor 13, gas introduction port 14 a for introducing source gas and carrier gas into reaction vessel 12, surplus gas of carrier gas and carrier gas obtained by growing an epitaxial film on silicon wafer 11 placed on susceptor 13 And a gas discharge port 14b for discharging the gas. The reaction vessel 12 includes a ring-shaped base member 16 that surrounds the susceptor 13 with a predetermined interval from the outer peripheral surface of the susceptor 13, an upper dome 17 that is located above the susceptor 13 and that bulges downward at the center, and a lower surface. The upper dome flange 18 that contacts the upper surface of the base member 16 and holds the upper dome 17, the lower dome 19 that is formed below the susceptor 13 and is formed in a conical cylindrical shape that becomes narrower downward, and the upper surface of the base member 16 A lower dome flange 21 that contacts the lower surface and holds the lower dome 19.

  The upper dome 17 is made of transparent quartz, and the upper dome flange 18 is made of opaque quartz. Then, the upper dome 17 is assimilated to the upper dome flange 18. That is, the upper dome 17 is welded and integrated with the upper dome flange 18 with a gas burner using a mixed gas of hydrogen and oxygen while being fitted into the ring-shaped upper dome flange 18. At this time, the upper dome 17 is assimilated (welded) to the upper dome flange 18 so that the lowermost surface of the upper dome 17 is located above the extended surface of the lower surface of the upper dome flange 18. With the upper dome flange 18 mounted on the base member 16, the upper dome flange 18 is mounted on the upper dome flange 18, and the upper dome flange 18 is sandwiched between the base member 16 and the upper fixed flange 22, thereby the upper dome flange. 18 is fixed to the base member 16. As described above, by positioning the lowermost surface of the upper dome 17 above the extended surface of the lower surface of the upper dome flange 18, the upper dome 17 with the upper dome flange 18 can be projected on the flat plate in a downwardly convex state. The lowermost surface of the upper dome 17 does not contact the flat plate before the lower surface of the upper dome contacts the flat plate, and the lowermost surface of the upper dome 17 is not damaged. Therefore, the upper dome 17 with the upper dome flange 18 can be handled relatively easily as a component.

  On the other hand, the lower dome 19 is made of transparent quartz, and the lower dome flange 21 is made of opaque quartz. The lower dome 19 is assimilated into the lower dome flange 21. That is, the upper end of the lower dome 19 is welded and integrated with the inner corner portion of the lower end of the ring-shaped lower dome flange 21 with a gas burner using a mixed gas of hydrogen and oxygen. Further, the lower end of the lower dome 19 is subjected to assimilation processing on the upper end of the cylindrical member 23 which is provided so as to extend in the vertical direction and is formed of opaque quartz. In other words, the lower end of the lower dome 19 is integrated with the upper end of the cylindrical member 23 by welding with a gas burner using a mixed gas of hydrogen and oxygen. With the upper surface of the lower dome flange 21 in contact with the lower surface of the base member 16, the lower fixing flange 24 is pressed against the lower surface of the lower dome flange 21, and the lower dome flange 21 is sandwiched between the base member 16 and the lower fixing flange 24. As a result, the lower dome flange 21 is fixed to the base member 16. Further, the cylindrical member is provided with a drive shaft 26 penetrating in the vertical direction, and the susceptor 13 provided in the reaction vessel 12 is fixed to the upper end portion of the drive shaft 26 via a plurality of arms 27. The lower end of the drive shaft 26 is connected to a drive motor (not shown) provided outside the reaction vessel 12. A gasket ring 28 is interposed in the gap between the cylindrical member 23 and the drive shaft 26, and the insertion portion of the drive shaft 26 into the reaction vessel 12 is sealed by the gasket ring 28.

  On the other hand, the curvature radius R of the upper dome 17 is set in the range of 4500 to 6000 mm, preferably 5000 to 5500 mm. Further, the distance H between the lowermost surface of the upper dome 17 and the extended surface of the lower surface of the upper dome flange 18 is set in the range of 1.0 to 3.5 mm, preferably 1.5 to 3.0 mm. Here, the radius of curvature R of the upper dome 17 is limited to the range of 4500 to 6000 mm. If the radius is less than 4500 mm, the flow of gas (source gas and carrier gas) in the vicinity of the center in the reaction vessel 12 becomes unstable. This is because the flow dependency increases, and if it exceeds 6000 mm, the difficulty of manufacturing the upper dome 17 increases and the strength of the upper dome 17 decreases. In addition, the distance H between the lowermost surface of the upper dome 17 and the extended surface of the lower surface of the upper dome flange 18 is limited to a range of 1.0 to 3.5 mm. An epitaxial film having a uniform thickness is too close to the wafer 11 and the flow of the mixed gas passing over the silicon wafer 11 is affected by the shape of the upper dome 17 and is curved as shown by the two-dot chain line arrow in FIG. If the thickness of the upper dome 17 exceeds 3.5 mm, the space between the lowermost surface of the upper dome 17 and the upper surface of the silicon wafer 11 widens, and the response to the gas flow rate becomes strong.

  The reason why the radius of curvature R of the upper dome 17 is limited to the range of 4500 to 6000 mm, and the distance H between the lowermost surface of the upper dome 17 and the extended surface of the lower surface of the upper dome flange 18 is limited to the range of 1.0 to 3.5 mm. Will be described in more detail. According to experiments, even if the radius of curvature R is less than 4500 mm or exceeds 6000 mm, the thickness distribution of the epitaxial film is deteriorated regardless of the flow rate of gas (source gas and carrier gas). Further, according to experiments, even if the distance H is less than 1.0 mm or exceeds 3.5 mm, the thickness distribution of the epitaxial film tends to be deteriorated regardless of the gas flow rate. Specifically, when the distance H is decreased, the flatness of the epitaxial film tends to be improved as the gas flow rate is increased. When the distance H is increased, the epitaxial film is increased as the gas flow rate is increased. The flatness of the gas tends to deteriorate and depends on the gas flow rate in any case. Furthermore, according to experiments, by limiting the radius of curvature R to within the range of 4500 to 6000 mm and limiting the distance H to within the range of 1.0 to 3.5 mm, regardless of the gas flow rate, An almost constant good film thickness distribution can be obtained. For these reasons, since the horizontal concentration distribution of the source gas directly above the wafer 11 changes according to the flow rate (flow rate) of the gas introduced into the reaction vessel 12, the flatness of the epitaxial film is reduced. Presumed to have occurred. That is, by setting the radius of curvature R in the range of 4500 to 6000 mm and setting the distance H in the range of 1.0 to 3.5 mm, the concentration of the source gas depending on the gas flow rate (flow rate). Since the influence on the distribution is suppressed, it is considered that a good result is obtained in which the thickness distribution of the epitaxial film is almost constant. On the other hand, the gas introduced into the reaction vessel 12 basically flows in a cylindrical reaction space from upstream to downstream, but there is room for the gas to diffuse horizontally and vertically with respect to the wafer 11 at that time. There is. It is considered that the radius of curvature R affects the gas diffusion in the horizontal direction, and the distance H affects the gas diffusion in the vertical direction. Also, since they interact, an optimal combination of the radius of curvature R and the distance H is required.

  From the above, it is interpreted as follows. The diffusion of the gas in the horizontal direction according to the curvature of the upper dome 17 basically tends to spread along the curved surface of the upper dome 17 when the curvature of the upper dome 17 is large (the curvature radius is small), and the gas spreads. If it is too much, or if the gas stays too much, the film thickness distribution will not be improved. Further, the gas spread is affected by the distance H which is a vertical component. That is, when the distance H is small, the gas is easily influenced by the horizontal direction. The numerical limitation on the upper dome 17 in the present invention (numerical range of the radius of curvature R and the distance H) suggests that there exists an equilibrium state, and the thickness distribution of the epitaxial film is less affected by the gas flow rate (flow rate). A shape and configuration capable of realizing a gas concentration that can be improved are shown. By setting the curvature radius R and the distance H within the above ranges, the difference in the height direction between the lowermost surface of the upper dome 17 and the upper end of the gas introduction port 14a is within the range of 16.0 to 18.5 mm. Is set.

  On the other hand, the epitaxial wafer manufacturing apparatus 10 stores a tank (not shown) for storing a source gas such as silane gas for growing an epitaxial film on the upper surface of the silicon wafer 11 and a tank (for storing a carrier gas such as hydrogen gas). (Not shown), a gas supply pipe 29 that is inserted into the base member 16 and introduces a reaction gas (raw material gas and carrier gas) into the reaction vessel 12, and an excess of the reaction gas that is inserted into the base member 16 A vertical direction is formed on the inner peripheral surface of the base member 16 in order to form the gas discharge pipe 31 discharged from the reaction vessel 12 and the gas introduction port 14a and the gas discharge port 14b communicating with the gas supply pipe 29 and the gas discharge pipe 31, respectively. And an upper liner 32 and a lower liner 33 arranged at a predetermined interval, and a gas for sucking and exhausting the reaction processing gas in the reaction vessel 12. Further comprising a decane 31. The gas supply pipe 29 and the gas discharge pipe 31 are provided so as to face each other about the drive shaft 26, extend in the radial direction about the drive shaft 26, and face the outer peripheral surface of the susceptor 13. The gas inlet 14a and the gas outlet 14b are formed by the upper liner 32 and the lower liner 33 so as to be positioned below the upper dome flange 18, respectively. That is, the gas inlet 14a and the gas outlet 14b face each other around the drive shaft 26, are formed in a flat shape extending in the horizontal direction, and face the outer peripheral surface of the silicon wafer 11 placed on the susceptor 13. The upper liner 32 and the lower liner 33 are formed. Reference numeral 34 in FIG. 1 denotes a halogen lamp (heating device) provided above and below the reaction vessel 12, respectively.

  A method of growing an epitaxial film on the silicon wafer 11 placed on the susceptor 13 using the epitaxial wafer manufacturing apparatus 10 configured as described above will be described. First, the silicon wafer 11 is placed on the susceptor 13. Next, the drive motor is driven to rotate the silicon wafer 11 through the drive shaft 26 and the susceptor 13, and the upper surface of the silicon wafer 11 and the lower surface of the susceptor 13 are heated by the halogen lamp 34. Gas and carrier gas) are fed into the reaction vessel 12. As a result, after the reaction gas passes through the silicon wafer 11, excess reaction gas not deposited on the silicon wafer 11 is discharged out of the reaction vessel 12 through the gas discharge port 14 b and the gas discharge pipe 31. . Here, the radius of curvature R of the upper dome 17 is within a predetermined range, and the distance H between the lowermost surface of the upper dome 17 and the extended surface of the lower surface of the upper dome flange 18 is within a predetermined range. Even if the flow rate of the gas supplied into the reaction vessel 12 is increased or decreased, the reaction processing gas flows linearly on the silicon wafer 11 as indicated by the broken-line arrows in FIG. That is, the shape of the upper dome 17 does not affect the gas flow on the silicon wafer 11 even if the flow rate of the gas supplied from the gas inlet 14 a into the reaction vessel 12 is changed. As a result, the upper dome 17 having the same shape is used on the silicon wafer 11 while maintaining the growth rate of a predetermined epitaxial film, without replacing the upper dome 17 with the curvature radius R of the upper dome 17 or the distance H changed. The epitaxial film can be grown to a uniform thickness.

  In the above embodiment, a silicon wafer is used as the semiconductor wafer. However, a silicon carbide (SiC) wafer, a gallium arsenide (GaAs) wafer, or the like may be used as the semiconductor wafer.

  Next, examples of the present invention will be described in detail together with comparative examples.

<Examples 1-3>
The epitaxial wafer manufacturing apparatus 10 shown in FIG. 1 uses the manufacturing apparatus 10 in which the curvature radius R of the upper dome 17 is 4500 mm and the distance H between the lowermost surface of the upper dome 17 and the lower surface of the upper dome flange 18 is 1.0 mm. The epitaxial growth process was performed under the following epitaxial growth process conditions. A silicon wafer 11 having a diameter and a thickness of 300 mm and 775 μm is placed on the susceptor 13, and a hydrogen gas flow rate (carrier gas flow rate) and a trichlorosilane gas (raw material gas) are allowed to flow for 60 seconds. Each film was grown. A silicon wafer epitaxially grown at a flow rate of hydrogen gas supplied into the reaction vessel 12 of 40 slm (standard liter / minute) is taken as Example 1, a silicon wafer grown epitaxially at 60 slm is taken as Example 2, and epitaxially grown at 80 slm. The silicon wafer subjected to the process is referred to as Example 3. The flow rate of trichlorosilane gas was constant (10 slm) regardless of the hydrogen gas flow rate.

<Examples 4 to 6>
Except that the curvature radius R of the upper dome was set to 5000 mm, silicon wafers epitaxially grown in the same manner as in Examples 1 to 3 were set as Examples 4 to 6, respectively.

<Examples 7 to 9>
Except that the radius of curvature R of the upper dome was 6000 mm, silicon wafers epitaxially grown in the same manner as in Examples 1 to 3 were set as Examples 7 to 9, respectively.

<Comparative Examples 1-3>
Except that the curvature radius R of the upper dome was set to 3000 mm, silicon wafers epitaxially grown in the same manner as in Examples 1 to 3 were used as Comparative Examples 1 to 3, respectively.

<Comparative Examples 4-6>
Comparative Examples 4 to 6 were silicon wafers that were epitaxially grown in the same manner as in Examples 1 to 3, except that the radius of curvature R of the upper dome was set to 7000 mm.

<Examples 10 to 12>
Using the manufacturing apparatus 10 in which the curvature radius R of the upper dome 17 of the epitaxial wafer manufacturing apparatus 10 shown in FIG. 1 is 4500 mm, and the distance H between the lowermost surface of the upper dome 17 and the extended surface of the lower surface of the upper dome flange 18 is 3.5 mm. The epitaxial growth process was performed under the following epitaxial growth process conditions. A silicon wafer 11 having a diameter and a thickness of 300 mm and 775 μm is placed on the susceptor 13, and a hydrogen gas flow rate (carrier gas flow rate) and a trichlorosilane gas (raw material gas) are allowed to flow for 60 seconds. Each film was grown. The silicon wafer epitaxially grown at a flow rate of hydrogen gas supplied into the reaction vessel 12 of 40 slm (standard liter / minute) is taken as Example 10, the silicon wafer grown epitaxially at 60 slm is taken as Example 11, and epitaxially grown as 80 slm. The silicon wafer which performed this was made into Example 12. FIG. The flow rate of trichlorosilane gas was constant (10 slm) regardless of the hydrogen gas flow rate.

<Examples 13 to 15>
Except that the curvature radius R of the upper dome was set to 5000 mm, silicon wafers epitaxially grown in the same manner as in Examples 10 to 12 were designated as Examples 13 to 15, respectively.

<Examples 16 to 18>
Except that the radius of curvature R of the upper dome was 6000 mm, silicon wafers that were epitaxially grown in the same manner as in Examples 10 to 12 were designated as Examples 18 to 19, respectively.

<Comparative Examples 7-9>
Comparative examples 7 to 9 were silicon wafers that were epitaxially grown in the same manner as in Examples 10 to 12 except that the radius of curvature R of the upper dome was set to 3000 mm.

<Comparative Examples 10-12>
Except that the curvature radius R of the upper dome was set to 7000 mm, silicon wafers epitaxially grown in the same manner as in Examples 10 to 12 were designated as Comparative Examples 10 to 12, respectively.

<Comparative Examples 13-15>
Using the manufacturing apparatus 10 in which the curvature radius R of the upper dome 17 of the epitaxial wafer manufacturing apparatus 10 shown in FIG. 1 is 3000 mm, and the distance H between the lowermost surface of the upper dome 17 and the extended surface of the lower surface of the upper dome flange 18 is 0 mm. Epitaxial growth processing was performed under the following epitaxial growth processing conditions. A silicon wafer 11 having a diameter and a thickness of 300 mm and 775 μm is placed on the susceptor 13, and a hydrogen gas flow rate (carrier gas flow rate) and a trichlorosilane gas (raw material gas) are allowed to flow for 60 seconds. Each film was grown. A silicon wafer epitaxially grown with a flow rate of hydrogen gas supplied into the reaction vessel 12 of 40 slm (standard liter / minute) is referred to as Comparative Example 13, a silicon wafer that has been epitaxially grown as 60 slm is referred to as Comparative Example 14, and is epitaxially grown as 80 slm. The silicon wafer subjected to the process was set as Comparative Example 15. The flow rate of trichlorosilane gas was constant (10 slm) regardless of the hydrogen gas flow rate.

<Comparative Examples 16-18>
Comparative Examples 16 to 18 were silicon wafers that were epitaxially grown in the same manner as Comparative Examples 13 to 15 except that the radius of curvature R of the upper dome was 4500 mm.

<Comparative Examples 19-21>
Comparative Examples 19 to 21 were silicon wafers that were epitaxially grown in the same manner as Comparative Examples 13 to 15 except that the curvature radius R of the upper dome was set to 5000 mm.

<Comparative Examples 22-24>
Comparative Examples 22 to 24 were silicon wafers that were epitaxially grown in the same manner as Comparative Examples 13 to 15 except that the radius of curvature R of the upper dome was set to 6000 mm.

<Comparative Examples 25-27>
Comparative examples 25-27 were silicon wafers that were epitaxially grown in the same manner as comparative examples 13-15, except that the radius of curvature R of the upper dome was 7000 mm.

<Comparative Examples 28-30>
The manufacturing apparatus 10 in which the radius of curvature R of the upper dome 17 of the epitaxial wafer manufacturing apparatus 10 shown in FIG. 1 is 3000 mm, and the distance H between the lowermost surface of the upper dome 17 and the lower surface of the upper dome flange 18 is 5.0 mm. The epitaxial growth process was performed under the following epitaxial growth process conditions. A silicon wafer 11 having a diameter and a thickness of 300 mm and 775 μm is placed on the susceptor 13, and a hydrogen gas flow rate (carrier gas flow rate) and a trichlorosilane gas (raw material gas) are allowed to flow for 60 seconds. Each film was grown. A silicon wafer epitaxially grown with a flow rate of hydrogen gas supplied into the reaction vessel 12 of 40 slm (standard liter / minute) is referred to as Comparative Example 28, a silicon wafer epitaxially grown as 60 slm is referred to as Comparative Example 29, and epitaxially grown as 80 slm. The silicon wafer subjected to the above was designated as Comparative Example 30. The flow rate of trichlorosilane gas was constant (10 slm) regardless of the hydrogen gas flow rate.

<Comparative Examples 31-33>
Except that the curvature radius R of the upper dome was 4500 mm, silicon wafers epitaxially grown in the same manner as in Comparative Examples 28 to 30 were referred to as Comparative Examples 31 to 33, respectively.

<Comparative Examples 34-36>
Comparative examples 34-36 were silicon wafers that were epitaxially grown in the same manner as in comparative examples 28-30, except that the radius of curvature R of the upper dome was set to 5000 mm.

<Comparative Examples 37-39>
Comparative examples 37-39 were silicon wafers epitaxially grown in the same manner as in comparative examples 28-30, except that the curvature radius R of the upper dome was 6000 mm.

<Comparative Examples 40-42>
Comparative Examples 40 to 42 were respectively silicon wafers that were epitaxially grown in the same manner as Comparative Examples 28 to 30 except that the curvature radius R of the upper dome was set to 7000 mm.

<Comparative test 1 and evaluation>
For the silicon wafers of Examples 1 to 18 and Comparative Examples 1 to 42, the thickness of the epitaxial film deposited on the silicon wafer was measured using a Fourier Transform Infrared Spectroscopy (FT-IR). Then, an index of the distribution flatness of the epitaxial film was calculated. Specifically, first, as shown in FIG. 3, line scans were performed at 5 mm pitches in four directions extending in the radial direction by changing the angle from the center of the wafer by 90 degrees. Next, the measurement points on the concentric circles are averaged, and a line segment extending in the radial direction from the center of the wafer and reaching the outer periphery of the wafer is divided into five regions every 30 mm, and the epitaxial in each of the sections 1 to 5 is divided. A value (L1 to L5) obtained by subtracting the minimum value from the maximum value of the film is obtained, and the percentage of the value (L / te) obtained by dividing each value by the target thickness te (epi thickness) of the epitaxial film is obtained. It was used as an index of distribution flatness. 4 to 7 show the results of calculating the value (L3 / te) × 100 in section 3 where the thickness variation of the epitaxial film is the largest as the maximum thickness variation of the epitaxial film. The section 1 (L1) is a section from the wafer center to 30 mm, the section 2 (L2) is a section from 30 mm to 60 mm, and the section 3 (L3) is a section from 60 mm to 90 mm. 4 (L4) is a section from 90 mm to 120 mm, and section 5 (L5) is a section from 120 mm to 150 mm. 4 shows Examples 1 to 9 and Comparative Examples 1 to 6, FIG. 5 shows Examples 10 to 18 and Comparative Examples 7 to 12, FIG. 6 shows Comparative Examples 13 to 27, FIG. 7 shows Comparative Examples 28-42.

On the other hand, the percentage of the value obtained by dividing the value obtained by subtracting the minimum value from the maximum value at all the measurement points of the thicknesses of the epitaxial films of Examples 1 to 18 and Comparative Examples 1 to 42 by the average value is the total thickness of the epitaxial film. Calculated as distribution (%). The results are shown in Table 1. In Table 1, R represents the radius of curvature of the upper dome, and H represents the distance between the lowermost surface of the upper dome and the extended surface of the lower surface of the upper dome flange. Further, when the thickness distribution of the epitaxial film is adjusted by changing the carrier gas flow rate or the like, the overall shape can be roughly tuned, but eventually the shape change in the section 3 (L3) region remains. Therefore, as described above, an index is set so that the flatness of the section 3 (L3) region and the flatness of the entire distribution can be evaluated together.

  As is apparent from FIGS. 4 to 7, in Comparative Examples 1 to 42, the maximum thickness variation ((L3 / te) × 100) of the epitaxial film was as large as 0.42 to 2.21%. In Examples 1 to 18, the maximum thickness variation ((L3 / te) × 100) of the epitaxial film was reduced to about 0.23 to 0.49%. From this, when the curvature radius R of the upper dome is set within a range of 4500 to 6000 mm, and the distance H between the lowermost surface of the upper dome and the extended surface of the lower surface of the upper dome flange is set within a range of 1.0 to 3.5 mm, It has been found that an epitaxial film can be grown to a uniform thickness on a silicon wafer regardless of the flow rate of hydrogen gas supplied into the apparatus.

  Further, as apparent from Table 1, in Comparative Examples 1 to 42, the overall distribution of the thickness of the epitaxial film was as large as 0.52 to 2.93%, whereas in Examples 1 to 18, the epitaxial film was The overall distribution of the thickness was as small as 0.28 to 0.69. Therefore, when the radius of curvature R of the upper dome is set within the range of 4500 to 6000 mm, and the distance H between the lowermost surface of the upper dome and the extended surface of the lower surface of the upper dome flange is set within the range of 1.0 to 3.5 mm. It has been found that the flatness of the overall distribution of the thickness of the epitaxial film is improved regardless of the flow rate of the hydrogen gas supplied into the apparatus.

10 Epitaxial wafer manufacturing equipment 11 Silicon wafer (semiconductor wafer)
12 Reaction vessel 13 Susceptor 14a Gas inlet 14b Gas outlet 17 Upper dome 18 Upper dome flange

Claims (2)

A susceptor on which a semiconductor wafer can be placed is provided in a reaction vessel having an upper dome that bulges downward in the center and an upper dome flange that holds the upper dome, and the upper dome is placed in a state where the semiconductor wafer is placed on the susceptor. An epitaxial film is grown on the semiconductor wafer by introducing a source gas and a carrier gas into the reaction vessel from a gas inlet located below the flange for use, and from a gas outlet located below the flange for the upper dome. In the method of manufacturing an epitaxial wafer that discharges excess gas,
The lowermost surface of the upper dome is configured to be positioned above the extended surface of the lower surface of the upper dome flange,
A radius of curvature of the upper dome is set within a range of 4500 to 6000 mm,
A method of manufacturing an epitaxial wafer, wherein a distance between a lowermost surface of the upper dome and an extended surface of a lower surface of the flange for the upper dome is set within a range of 1.0 to 3.5 mm. A reaction vessel having an upper dome that bulges downward in the center and an upper dome flange that holds the upper dome, a susceptor provided in the reaction vessel on which a semiconductor wafer can be placed, and a lower position than the upper dome flange. A gas inlet for introducing a source gas and a carrier gas into the reaction vessel, and a gas outlet for discharging the source gas and the carrier gas located opposite to the gas inlet and positioned below the upper dome flange. In the provided epitaxial wafer manufacturing apparatus,
The lowermost surface of the upper dome is configured to be located above the extended surface of the lower surface of the upper dome flange,
A radius of curvature of the upper dome is set within a range of 4500 to 6000 mm,
The epitaxial wafer manufacturing apparatus, wherein the distance between the lowermost surface of the upper dome and the extended surface of the lower surface of the flange for the upper dome is set in a range of 1.0 to 3.5 mm.

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