JP5413305B2 - Epitaxial growth equipment - Google Patents

Description

  The present invention relates to an epitaxial growth apparatus for epitaxially growing a single crystal thin film on a substrate.

  In the manufacturing process of a semiconductor device, there is a process of epitaxially growing a thin film on a semiconductor substrate. FIG. 9 shows a schematic diagram of such a conventional epitaxial growth apparatus used for epitaxial growth. In the epitaxial growth process using the epitaxial growth apparatus 104 shown in FIG. 9, the reactive gas 105 from the gas supply source 106 is applied to the substrate W placed on the susceptor 109 by the gas supply means 102 in the chamber 101 in which the outside air is shut off. A gas phase reaction is caused on the substrate W by the supplied source gas 105 to epitaxially grow the thin film, and then the gas after the reaction is discharged out of the chamber 101 by the gas discharge means 103.

  Epitaxial growth using such a device is used to increase the breakdown voltage of a bipolar device in the manufacturing process of a semiconductor device. When a megabit memory is also manufactured in the device, a soft error or latch-up due to alpha rays is used. It is a necessary technology to prevent this.

  In order to deposit an epitaxial layer smoothly, for example, when producing an epitaxial wafer using such an epitaxial growth apparatus, it is important to reduce unevenness in the flow rate of the source gas on the substrate surface. However, since the diameter of the substrate is currently increased to 300 mm and is processed in a single wafer type, it is very difficult to form a flow having a wide range and no flow rate unevenness. Therefore, the thickness distribution of the epitaxial layer of the epitaxial wafer is often formed with unevenness corresponding to the flow of the source gas.

  In order to solve such a problem, there is an apparatus in which the gas supply means 102 is made into a tree-like gas flow path that branches into a plurality in the horizontal direction in the apparatus 104 as shown in FIG. FIG. 10 shows a schematic view from the upper surface of the gas supply means 102 having a tree-like gas flow path through which gas flows in the horizontal direction. In such an apparatus, since the flow rates of the gas 105 ejected from a plurality of gas ejection ports connected to one gas supply source 106 are substantially the same, the flow velocity distribution in the substrate W plane of the supplied gas 105 is uniform. The thickness distribution of the epitaxial layer is improved. Patent Document 1 discloses an apparatus having such a tree-like gas supply means.

Special table 2008-516084 gazette JP 2009-277730 A

  However, although the thickness distribution of the epitaxial layer can be improved by the apparatus having the gas supply means as described above, the gas flow rate unevenness in the gas flow path is caused to be precise, and the gas flow rate in the substrate surface is also accurate. Unevenness becomes worse and insufficient. This is because, in a tree-like gas flow path, the flowed gas must pass through a right-angled corner after each branch of the gas flow path, and flow velocity unevenness occurs in the gas flow path by passing through this right-angled corner, This is because the gas is not equally distributed in the subsequent branch. In order to solve such a problem, a technique such as Patent Document 2 is effective. However, since a rectifying flow path having a certain size is provided in the flow path after branching, the processing is reduced when the flow path width is reduced. There was a limit.

  The present invention has been made in view of the above problems, and has a simple structure, can suppress the uneven flow velocity of the gas ejected from the tree-like gas flow path, and further improve the thickness distribution of the epitaxial layer. An object of the present invention is to provide an epitaxial growth apparatus that can reduce the size of the apparatus.

  In order to achieve the above object, the present invention provides at least a chamber in which a susceptor on which a substrate to be epitaxially grown is placed, and a substrate placed on the susceptor in the chamber from a gas supply source. An epitaxial growth apparatus comprising a gas supply means for supplying a gas and a gas discharge means for discharging the supplied gas to the outside of the chamber, wherein the gas supply means includes at least a plurality of flow paths downstream. A tree-like gas flow path that branches into a gas flow path, and a gas reservoir having a semicircular cross-section is formed in at least one outer corner of the tree-like gas flow path. An epitaxial growth apparatus is provided.

  In this way, if a gas reservoir having a semicircular cross section is formed in at least one outer corner of the tree-like gas flow path, a gas having a high flow velocity passing through the outer corner is generated in the gas reservoir. Since the flow velocity distribution is adjusted by the linear gas flow channel that flows to the inside of the gas flow channel and then continues to the gas reservoir, and uneven flow velocity in the flow channel can be easily suppressed with a simple structure. At the branch, the gas is branched to an equal flow rate. In addition, since it is a tree-shaped gas flow path, it can be efficiently distributed to a uniform gas flow rate by branching the flow path with a small gas supply source. As described above, according to the present invention, the gas can be evenly branched by suppressing uneven flow velocity in the gas flow path with a simple structure and supplied with a uniform gas flow velocity distribution in the substrate surface. Therefore, the device can be made compact and can grow an epitaxial layer having a uniform film thickness.

At this time, it is preferable that the semicircular cross section of the gas reservoir has a radius equal to or larger than the flow path width of the tree-shaped gas flow path.
Thus, if the semicircular cross section of the gas reservoir has a radius equal to or larger than the flow path width of the tree-shaped gas flow path, it is sufficient to suppress the flow velocity unevenness in the gas flow path. A space is formed, and the apparatus can more effectively suppress the uneven flow velocity at the corner portion.

At this time, it is preferable that the tree-shaped gas flow path is formed by forming a straight gas flow path having a length of 10 mm or more following the gas reservoir.
In this way, if a linear gas flow path having a length of 10 mm or more is formed following the gas reservoir, the flow rates mixed in the gas reservoir differ in the linear gas flow path. The gas is sufficiently mixed so that the apparatus has a more uniform flow rate.

At this time, the tree-shaped gas flow path is a gas flow in the vertical direction as a whole, the gas supply means is connected to the downstream end of the tree-shaped gas flow path, and the tree-shaped gas flow path It is preferable to have a horizontal gas flow path that blows out gas from the gas flow path in the horizontal direction and supplies the gas to the substrate placed on the susceptor.
In this way, the tree-like gas flow path is a gas flow in the vertical direction as a whole, and the gas supply means is connected to the downstream end of the tree-like gas flow path, and the tree-like gas flow path If a horizontal gas flow path is provided for supplying gas to the substrate placed on the susceptor by blowing out gas from the horizontal direction, the gas flowing in the vertical direction is connected to the horizontal gas flow path. Since the gas flow once dispersed is uniformly aligned toward the gas ejection port and then ejected in the horizontal direction, the gas can be supplied more uniformly within the substrate surface. .

  As described above, according to the present invention, it is possible to supply gas uniformly to a substrate with a simple structure and suppressing flow rate unevenness in the gas flow path. This makes it possible to form an epitaxial layer having a uniform film thickness distribution.

It is the schematic which shows an example of the embodiment of the epitaxial growth apparatus of this invention. It is the schematic which shows an example of the tree-shaped gas flow path of the epitaxial growth apparatus of this invention. In Example 1, it is explanatory drawing which shows the flow velocity distribution of the gas in a substrate surface. 3 is a graph showing a film thickness distribution of an epitaxial layer grown in Example 1. FIG. It is the schematic which shows the gas flow path of the epitaxial growth apparatus used by the comparative example. In a comparative example, it is explanatory drawing which shows the flow velocity distribution of the gas in a substrate surface. It is a graph which shows the film thickness distribution of the epitaxial layer grown in the comparative example. 6 is a graph showing a film thickness distribution of an epitaxial layer grown in Example 2. It is the schematic which shows an example of the conventional epitaxial growth apparatus. It is the schematic which shows an example of the gas supply means of the conventional epitaxial growth apparatus.

Hereinafter, the present invention will be described in detail as an example of an embodiment with reference to the drawings, but the present invention is not limited thereto.
FIG. 1 is a schematic view showing an example of an embodiment of an epitaxial growth apparatus of the present invention. FIG. 2 is a schematic view showing an example of a tree-like gas flow path of the epitaxial growth apparatus of the present invention.

  First, the epitaxial growth apparatus 14 of the present invention shown in FIG. 1 has a chamber 11 in which a susceptor 19 on which a substrate W to be epitaxially grown is placed, and a substrate W placed on the susceptor 19 in the chamber 11. A gas supply unit 12 that supplies the gas 15 from the supply source 16 and a gas discharge unit 13 that discharges the reacted gas to the outside of the chamber 11 are provided.

In addition, the epitaxial growth apparatus 14 of the present invention may appropriately include a susceptor rotating mechanism 20 for rotating the susceptor 19, a lamp heating apparatus (not shown) for heating the substrate W, and the like.
The susceptor rotating mechanism 20 is for rotating the substrate W by rotating the susceptor 19 so that epitaxial growth is performed uniformly in the substrate surface.

And in this invention, as shown in FIG. 2, the gas supply means 12 is equipped with the tree-shaped gas flow path 18 branched to a some flow path toward the downstream, This tree-shaped gas flow path A gas reservoir 21 having a semicircular cross section is formed at at least one outer corner of 18.
By forming the gas reservoir 21, the flow with a high velocity outside the corner goes to the inside of the continuous linear gas flow path, and the gas velocity distribution is adjusted within the flow path. Such an apparatus of the present invention has a simple shape as compared with the apparatus of Patent Document 2, and thus can be easily processed and applied to a narrow flow path. Further, in order to eliminate the flow velocity unevenness, the straight gas flow path after passing through the corner is not made longer than necessary, and the straight gas flow path after passing through the corner can be shortened. (Injection) It can also contribute to downsizing itself. With such a tree-like gas flow path 18, there is little variation in the flow rate of the gas in the flow path, so that the gas from the gas supply source 16 can be evenly branched, and the large diameter on the susceptor 19 The gas can be efficiently and uniformly supplied to the substrate W in the plane. Therefore, if the apparatus of the present invention is used, the gas can be supplied uniformly within the substrate surface with a simple structure, so that an epitaxial layer having a uniform film thickness can be grown on a large-diameter wafer, and the apparatus is compact. Is possible.

At this time, it is preferable that the semicircular cross section of the gas reservoir 21 has a radius equal to or larger than the channel width of the tree-like gas channel 18.
Since the gas reservoir 21 having such a radius has a sufficient space for rectification, the gas flow rate in the gas reservoir 21 is more effectively equalized.

Further, it is preferable that the tree-like gas flow path 18 is formed by forming a straight gas flow path having a length of 10 mm or more following the gas reservoir 21.
Thus, if the length L of the linear gas flow path following the gas reservoir 21 is 10 mm or more, different flow velocities mixed in the gas reservoir 21 while the gas flows in the linear gas flow path. The gas is sufficiently long to uniformly mix and eliminate the flow velocity unevenness.

As shown in FIGS. 1 and 2, the tree-shaped gas flow path 18 has a gas flow in the vertical direction as a whole, and the gas supply means 12 has an end portion downstream of the tree-shaped gas flow path 18. It is preferable to include a horizontal gas flow path 17 that is connected to and supplies gas to the substrate W placed on the susceptor 19 by ejecting gas from the tree-shaped gas flow path 18 in the horizontal direction.
As described above, when the gas flowing in the vertical direction at a uniform flow rate by the tree-shaped gas flow path 18 of the present invention hits the L-shaped outer corner surface when flowing into the horizontal gas flow path 17, the flow speed unevenness is reduced. It can suppress more and can supply gas more uniformly. Further, if the tree-like gas flow path 18 is arranged to flow in the vertical direction to form an L-shaped flow path as a whole, there is no need to increase the horizontal apparatus width even if a large number of flow paths are branched. It is advantageous in terms of space. In contrast to FIG. 1, the tree-like gas flow path 18 may be arranged so as to flow upward from below, and may have an inverted L-shape as a whole. However, as shown in FIG. 1, the tree flows downward from above. The flow rate unevenness can be further suppressed by using the gas channel 18.

  Further, the gas reservoir 21 of the present invention may be formed at any one or more outer corners of the tree-shaped gas flow path 18, and the same stage of the tree-shaped gas flow path 18 as shown in FIG. 2. If the gas reservoirs 21 are formed in all the outer corners of the substrate, it is easy to supply gas at a uniform flow rate within the substrate surface, or if it is formed in all of the corner portions before branching of the flow path, all The gas flow rate distributed at the time of branching is equalized and is most preferable.

  With such an epitaxial growth apparatus of the present invention, gas can be supplied at a uniform flow rate in the substrate surface, so that an epitaxial layer having a uniform film thickness can be formed.

EXAMPLES Hereinafter, although an Example and a comparative example are shown and this invention is demonstrated more concretely, this invention is not limited to these.
Example 1
Epitaxial growth was performed on a silicon wafer having a diameter of 300 mm using the epitaxial growth apparatus of the present invention in which a plurality of tree-like gas flow paths of the present invention having gas reservoirs shown in FIG. In addition, the outlets of the gas supply means in which a plurality of tree-like gas flow paths are arranged horizontally are 96 ports in total.
The epitaxial growth conditions were a reaction temperature of 1150 ° C., a hydrogen flow rate of 70 slm, a TCS (trichlorosilane) gas flow rate of 10 slm, and an epitaxial layer was grown to a film thickness of 5 μm.

  FIG. 3 shows the gas flow velocity distribution in the substrate surface, and FIG. 4 shows the deviation of the film thickness distribution of the epitaxial layer.

(Comparative example)
The epitaxial layer was grown under the same apparatus and conditions as in Example 1 except that the tree-shaped gas flow path having a right outer corner with no gas reservoir portion shown in FIG. 5 was used.
FIG. 6 shows the gas flow velocity distribution in the substrate surface, and FIG. 7 shows the deviation of the film thickness distribution of the epitaxial layer.

(Example 2)
A plurality of the tree-like gas flow paths of the present invention are arranged so that gas flows in the vertical direction with respect to the substrate, and an L-shaped gas supply means having a horizontal gas flow path connected to the downstream end thereof is attached in FIG. An epitaxial layer was grown under the same conditions as in Example 1 except that the apparatus was used. FIG. 8 shows the deviation of the film thickness distribution of the epitaxial layer.

  Comparing Example 1 and the comparative example, as can be seen from FIGS. 3 and 6, the gas flow velocity distribution in the substrate surface is better in Example 1 of FIG. 3, and as a result, FIG. 4 and FIG. As shown in FIG. 7, the film thickness uniformity of the grown epitaxial layer is better in Example 1 of FIG. Further, when Example 1 and Example 2 were compared, the film thickness uniformity was better in Example 2 shown in FIG. Thus, as in the present invention, if the gas reservoir is formed in the tree-like gas flow path, the gas flow velocity distribution is good and the membrane is better than the tree-like gas flow path without the gas reservoir. It has been found that a uniform epitaxial layer can be grown. In particular, among the first and second embodiments in which the gas reservoir is formed, the gas flow velocity distribution of the L-shaped channel of the second example is more uniform than the horizontal channel of the first example, and the membrane It has been found that an epitaxial layer with better thickness uniformity can be grown.

  The present invention is not limited to the above embodiment. The above-described embodiment is an exemplification, and the present invention has substantially the same configuration as the technical idea described in the claims of the present invention, and any device that exhibits the same function and effect is the present invention. It is included in the technical scope of the invention.

11 ... Chamber, 12 ... Gas supply means, 13 ... Gas discharge means,
14 ... epitaxial growth apparatus, 15 ... gas, 16 ... gas supply source,
17 ... Horizontal gas flow path, 18 ... Tree-shaped gas flow path, 19 ... Susceptor,
20 ... Susceptor rotation mechanism, 21 ... Gas reservoir, W ... Substrate.

Claims (4)

At least a chamber in which a susceptor on which a substrate to be epitaxially grown is placed is installed, gas supply means for supplying a gas from a gas supply source to the substrate placed on the susceptor in the chamber, and the supply An epitaxial growth apparatus comprising a gas discharge means for discharging the gas out of the chamber,
The gas supply means includes at least a tree-like gas flow path branched into a plurality of flow paths toward the downstream, and a portion where the gas flow of at least one outer corner of the tree-like gas flow path hits An epitaxial growth apparatus characterized in that a gas reservoir having a semicircular cross section is formed in the longitudinal cross section of the tree-like gas flow path .   2. The epitaxial growth apparatus according to claim 1, wherein the semicircular cross section of the gas reservoir has a radius equal to or larger than a flow path width of the tree-shaped gas flow path.   The said tree-shaped gas flow path is a thing in which the linear gas flow path of the length of 10 mm or more was formed following the said gas reservoir part, The Claim 1 or Claim 2 characterized by the above-mentioned. Epitaxial growth equipment.   The tree-shaped gas flow path is a gas flow in the vertical direction as a whole, and the gas supply means is connected to the downstream end of the tree-shaped gas flow path, and the tree-shaped gas flow path A horizontal gas flow path is provided for supplying gas to a substrate placed on the susceptor by jetting gas from the horizontal direction in a horizontal direction. The epitaxial growth apparatus described in 1.

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