JP2019114699A - Epitaxial growth system and semiconductor epitaxial wafer manufacturing method using the same - Google Patents

Abstract

To provide an epitaxial growth system capable of improving robustness in control of film thickness uniformity at the time of forming an epitaxial layer.SOLUTION: An epitaxial growth system 100 has: a susceptor 20 where a semiconductor wafer W is placed; a first gas supply part 150 for supplying a first process gas G1 to an upper surface of the semiconductor wafer W; and a second gas supply part 170 for supplying a second process gas G2 which controls a gas flow of the first process gas G1 around an outer edge of the semiconductor wafer W, in which the second gas supply part is arranged in such a manner that a main channel F of the second process gas G2 flows in on the susceptor 20 when the first and second process gases G1, G2 are simultaneously supplied and the main channel is isolated from a circumference of the semiconductor wafer W.SELECTED DRAWING: Figure 4

Description

  The present invention relates to an epitaxial growth apparatus and a method of manufacturing a semiconductor epitaxial wafer using the same.

  An epitaxial wafer is obtained by vapor-phase growing an epitaxial film on the surface of a semiconductor wafer. For example, when crystal integrity is more required or multilayer structures with different resistivities are required, a single crystal silicon thin film is vapor-phase grown (epitaxial growth) on a silicon wafer to manufacture an epitaxial silicon wafer. Do.

For example, a single wafer type epitaxial growth apparatus is used to manufacture an epitaxial wafer. Here, a general single wafer type epitaxial growth apparatus will be described with reference to FIG. As shown in FIG. 1, the epitaxial growth apparatus 900 has a chamber 10 including an upper dome 11, a lower dome 12 and a dome attachment 13, and the chamber 10 defines an epitaxial film forming chamber. Further, the dome mounting body 13 is divided into an upper liner 17 and a lower liner 18 at the boundary of the susceptor. The chamber 10 is provided with a reaction gas supply port 15A and a reaction gas discharge port 16A for supplying and discharging the reaction gas _GP respectively on the side of the upper liner 17 opposite to the side surface thereof. Further, the lower liner 18 side at a position opposing sides of the chamber 10, the supply and the respective atmospheric gas supply port 15B and the ambient gas to discharge the atmospheric gas G _A in order to keep the portion of the chamber in the lower dome 12 to a hydrogen atmosphere An outlet 16B is provided.

Further, in the chamber 10, a susceptor 20 on which the semiconductor wafer W is mounted is disposed. The susceptor 20 is supported by the susceptor support shaft 30 from below. The susceptor support shaft 30 engages and supports the lower surface outer peripheral portion of the susceptor 20 with three support pins (not shown) at the tip of the arm. Furthermore, three through holes (one of which is not shown) are formed in the susceptor 20, and one through hole is also formed in the arm of the susceptor support shaft 30. The lift pins 40A, 40B, and 40C (however, the lift pins 40B are not shown in the schematic cross-sectional view of FIG. 1) are inserted through the through holes of the arms and the through holes of the susceptor. Further, the lower end portion of the lift pin 40 is supported by the lift shaft 50. At the time of supporting the semiconductor wafer W carried into the chamber 10, mounting the semiconductor wafer W on the susceptor 20, and unloading the epitaxial wafer after vapor phase epitaxial growth out of the chamber 20, the elevating shaft 50 By moving up and down, the lift pins 40 move up and down while sliding on the through holes of the arm and the through holes of the susceptor, and the semiconductor wafer W is moved up and down at its upper end. When forming the epitaxial layer EP using the single wafer type epitaxial growth apparatus 900, the reaction gas _GP is brought into contact with the upper surface of the semiconductor wafer W mounted on the susceptor 20 while rotating the susceptor 20. Further, the reaction gas G _p, means a gas obtained by mixing a source gas to the carrier gas. When forming a silicon epitaxial layer as the epitaxial layer EP, a silicon source gas such as trichlorosilane gas is used as a source gas. The side surface of the susceptor 20 is generally covered by the preheat ring 60 via a gap of about 3 mm.

Preheat ring 60 is also referred to as a preheat ring or preheat ring, reaction gas G _P flows into the epitaxial film forming chamber, before the reaction gas G _P is in contact with the semiconductor wafer W, the pre-heat ring 60 susceptor 20 and the reaction gas The _GP is preheated to enhance the thermal uniformity of the semiconductor wafer W before and during the film formation, thereby enhancing the uniformity of the epitaxial film.

In the reaction gas outlet 16A and the ambient gas discharge port 16B side, with reference to FIG. 2 will be described with respect to the flow of the gas stream of the reaction gas G _P and the atmospheric gas G _A. As shown in FIG. 2, the reaction gas G _P mainly flows in the reaction gas outlet 16A side, the atmospheric gas G _A flows primarily ambient gas outlet 16B side. Through the gap g between the susceptor 20 and the preheat ring 60, to a portion of the reaction gas G _P is obtained sinks atmosphere gas outlet 16B side, on the contrary, the atmospheric gas G _A has a portion reactive gas It can blow up to the discharge port 16A side. However, unlike the reaction gas G _p , the atmosphere gas G _A is not basically intended to be supplied toward the upper surface of the semiconductor wafer W.

  Here, Patent Document 1 discloses, in an epitaxial growth apparatus, a first set of jets for supplying an angled injection of a first process gas at an angle with respect to a planar surface, and the jets. A second set of jets proximate the first set of outlets for supplying a pressurized laminar flow of a second process gas substantially along said planar surface; said planar surface A gas injection device is disclosed, which extends perpendicularly to the second set of jets.

  According to Patent Document 1, by using these two types of jets, an interaction is generated in the flow between process gases used at the time of epitaxial layer deposition, and the thickness and compositional nonuniformity of the epitaxial layer are generated. Or try to improve both of them.

Japanese Patent Publication No. 2015-534283 gazette

  The inventors of the present invention have experimented on the expectation that the film thickness uniformity when forming the epitaxial layer EP on the semiconductor wafer W can be favorably controlled by using the epitaxial growth apparatus 800 shown in FIG. 3. Here, the epitaxial growth apparatus 800 includes a first gas supply unit 15 that supplies the first process gas G1 to the upper surface of the semiconductor wafer W, and includes a first discharge port 15A that releases the first process gas G1 containing the reaction gas Gp. , And a second discharge port 70A for releasing a second process gas G2 for controlling the gas flow of the first process gas G1 at the peripheral portion of the semiconductor wafer W, and supplying the second process gas G2 in the upper surface direction of the semiconductor wafer W And a second gas supply unit 70. Then, as shown in FIG. 3, when the semiconductor wafer W is viewed from the top, the supply directions of the first process gas G1 and the second process gas G2 vertically intersect.

  When the epitaxial growth apparatus 800 is used, it is expected that the film thickness uniformity of the epitaxial layer EP can be improved because the first process gas G1 uniformly flows also to the wafer peripheral portion. However, when the epitaxial layer EP is actually formed, as shown in FIG. 7B which will be described in detail later, it is confirmed that swelling (roll-up and further roll-off) at the wafer peripheral portion may occur. The Since the film thickness of the epitaxial peripheral portion (wafer edge portion) is required to change monotonically decreasing or monotonically increasing, the formation of such a bump is unacceptable.

  It has also been confirmed that the formation of such bumps is greatly influenced by the number of rotations of the susceptor 20 and the supply ratio of the first process gas G1 at the central portion and the peripheral portion of the wafer. Therefore, when using the second process gas G2, the present inventors recognized as a new problem that it is necessary to improve the robustness of film thickness uniformity control at the time of forming an epitaxial layer.

  Therefore, the present invention provides an epitaxial growth apparatus capable of improving the robustness of film thickness uniformity control at the time of forming an epitaxial layer. Another object of the present invention is to provide a method of manufacturing a semiconductor epitaxial wafer using this epitaxial growth apparatus.

  The present inventors diligently studied to solve the above problems. During the epitaxial growth, by rotating the susceptor 20, the semiconductor wafer W mounted thereon is also rotated, and the process gas G1 is sprayed onto the upper surface of the semiconductor wafer W. Therefore, as the susceptor 20 and the semiconductor wafer W rotate, the gas flows of the first process gas G1 and the second process gas G2 also change, which can be considered as one of the causes of disturbance. As a result of further investigation, as schematically shown in FIG. 3, a region where the concentration of the first process gas G1 is locally increased between the second process gas G2 and the discharge port 16A in the rotational direction of the susceptor 20 Have been formed, which may be responsible for the formation of the bumps described above.

  Therefore, in the case where the second process gas G2 is used, in order to make the concentration distribution on the upper surface of the semiconductor wafer W uniform, the direction of the gas flow of the second process gas G2 is made appropriate to make the first process gas G1. The inventors conceived of controlling the gas flow of The inventors have found that the problem can be solved by using an epitaxial growth apparatus in which the direction of gas flow of the second process gas G2 is optimized, and the present invention has been completed.

That is, the gist configuration of the present invention is as follows.
(1) An epitaxial growth apparatus for vapor phase epitaxial growth of an epitaxial layer on the surface of a semiconductor wafer, comprising:
A chamber,
A susceptor for mounting the semiconductor wafer inside the chamber;
A first gas supply unit for supplying a first process gas to a top surface of the semiconductor wafer, comprising: a first discharge port for releasing a first process gas containing a reaction gas for vapor phase epitaxial growth of the epitaxial layer;
A second gas supply port for discharging a second process gas for controlling the gas flow of the first process gas at the peripheral portion of the semiconductor wafer, and a second gas for supplying the second process gas in the direction of the upper surface of the semiconductor wafer The supply department,
Have
The main flow path of the gas flow of the second process gas when simultaneously supplying the first and second process gas flows onto the susceptor, and the main flow path is separated from the periphery of the semiconductor wafer. An epitaxial growth apparatus characterized in that a second gas supply unit is disposed.

(2) The epitaxial growth apparatus has a discharge port for discharging the first process gas at a position facing the first gas discharge port,
The epitaxial growth apparatus according to (1), wherein the second gas discharge port is disposed on the rotational direction upstream between the first gas discharge port and the discharge port in the rotation direction of the susceptor.

(3) The epitaxial growth apparatus according to (2), wherein the second gas discharge port is disposed upstream of the first process gas in the rotation direction of the susceptor.

(4) An angle formed by a first direction from the first gas discharge port to the discharge port and a discharge direction from which the second process gas is discharged from the second gas discharge port is an acute angle 2) or the epitaxial growth apparatus as described in (3).

(5) The epitaxial growth apparatus according to (4), wherein an angle formed by the first direction and the emission direction is in a range of 40 degrees to 80 degrees.

(6) The first process gas includes a source gas and a carrier gas,
The epitaxial growth apparatus according to any one of (1) to (5), wherein the second process gas comprises the carrier gas.

(7) The epitaxial growth apparatus according to any one of (1) to (6), wherein the shortest distance between the peripheral edge of the semiconductor wafer and the main flow channel of the second process gas is 5 mm or more and 40 mm or less.

(8) mounting a semiconductor wafer on the susceptor of the epitaxial growth apparatus according to any one of (1) to (7);
And d) simultaneously supplying the first process gas and the second process gas to vapor-phase epitaxially grow an epitaxial layer on the surface of the semiconductor wafer.

  According to the present invention, there is provided an epitaxial growth apparatus capable of improving the robustness of film thickness uniformity control at the time of forming an epitaxial layer. Furthermore, according to the present invention, it is possible to provide a method of manufacturing a semiconductor epitaxial wafer using this epitaxial growth apparatus.

It is a schematic cross section of the epitaxial growth apparatus by a prior art. It is a schematic cross section explaining the gas flow near the gas outlet of an epitaxial growth device. It is a model top view of the epitaxial growth apparatus containing the 2nd process gas by the present inventors' examination. FIG. 1 is a schematic plan view of an epitaxial growth apparatus according to an embodiment of the present invention. It is a schematic diagram which shows the main flow path F of 2nd process gas. It is an example of mass concentration distribution of source gas controlled by the 2nd process gas. FIG. 6 is a view showing a mass concentration distribution of a first process gas in Example 1. FIG. 7 is a view showing a mass concentration distribution of the first process gas in Comparative Example 1; 5 is a graph showing the film thickness distribution at the peripheral portion of the epitaxial layer formed in Example 1. FIG. 15 is a graph showing the film thickness distribution at the peripheral portion of the epitaxial layer formed in Comparative Example 1. It is a graph which shows the relationship between the gas flow rate of the 2nd process gas in Example 1 at the time of changing growth conditions, and the film thickness difference in a wafer peripheral part. It is a graph which shows the relationship between the gas flow rate of the 2nd process gas in the comparative example 1 at the time of changing growth conditions, and the film thickness difference in a wafer peripheral part.

  Hereinafter, an epitaxial growth apparatus 100 according to the present invention will be described with reference to the drawings. In addition, the aspect ratio of each structure in a figure is illustrated exaggeratingly for convenience of explanation, and is different from the actual. Further, in order to simplify the description, block diagrams are appropriately used for each configuration. Furthermore, the same reference numerals are used for configurations overlapping with the general epitaxial growth apparatus 900 described above with reference to FIG.

(Epitaxial growth system)
An epitaxial growth apparatus 100 according to an embodiment of the present invention is an epitaxial growth apparatus that can be used to vapor phase epitaxially grow an epitaxial layer EP on the surface of a semiconductor wafer W to produce a semiconductor epitaxial wafer EW. This epitaxial growth apparatus 100 will be described with reference to FIGS. 1 and 4.

  The epitaxial growth apparatus 100 according to the present embodiment includes a chamber 10, a susceptor 20 for mounting a semiconductor wafer W inside the chamber 10, and a first gas supply unit 150 for supplying a first process gas G1 to the upper surface of the semiconductor wafer. And a second gas supply unit 170 configured to supply a second process gas G2 in the upper surface direction of the semiconductor wafer W. Here, the first gas supply unit 150 includes a first discharge port 150A for discharging a first process gas G1 including a reaction gas for vapor phase epitaxial growth of the epitaxial layer EP. In addition, the second gas supply unit 170 includes a second discharge port 170A that releases a second process gas G2 that controls the gas flow of the first process gas G1 in the peripheral portion of the semiconductor wafer W. Note that FIG. 4 illustrates an exhaust port 160 for exhausting the first process gas G1 at a position facing the first gas exhaust port 150A.

For convenience of explanation, the direction from the discharge port 160 toward the first gas supply unit 150 is defined as the x-axis, and the direction facing the second gas supply unit 170 is the y-axis. Define as In addition, the thickness direction of the semiconductor wafer W is taken as the z direction (the side on which the epitaxial layer EP is to be formed is taken as the positive direction of the z axis). Furthermore, the central position of the semiconductor wafer W is defined as the origin of this xyz space. Further, the y-axis, and the center position of the second outlet 170A defines an angle theta ₁ with. Furthermore, a first direction from the first gas discharge port 150A toward the discharge port 160 (that is, the negative direction of the x axis) and a discharge direction in which the second process gas G2 is discharged from the second gas discharge port 170A are formed. the angle is defined as the angle theta _2.

  The first process gas G1 contains a reaction gas, and the reaction gas is used to form an epitaxial layer EP on the surface of the semiconductor wafer W. Therefore, the first process gas G1 is supplied to the upper surface of the semiconductor wafer W. In the present specification, the reaction gas means a gas in which a source gas is mixed with a carrier gas. On the other hand, since the second process gas G2 controls the gas flow of the first process gas G1, it is not necessary to supply the second process gas G2 to be in direct contact with the upper surface of the semiconductor wafer W. By supplying the second process gas G2 in the direction of the top surface of the semiconductor wafer W, the second process gas G2 controls the flow of the first process gas G1.

Here, in the epitaxial growth apparatus 100 according to the present embodiment, the main flow path F of the gas flow of the second process gas G2 when the first and second process gases G1, G2 are simultaneously supplied flows onto the susceptor 20, and as the main flow path F is separated from the periphery W ₀ of the semiconductor wafer W, the second gas supply unit 170 is disposed.

  The main flow path F of the gas flow of the second process gas G2 will be described with reference to FIGS. 4 and 5A and 5B. FIG. 5A schematically describes the main flow path F of the second process gas when the first process gas G1 and the second process gas G2 flow while the susceptor 20 is rotated by the epitaxial growth apparatus 100 according to the present embodiment. It is The main flow path F of the gas flow of the second process gas G2 mentioned here indicates the flow direction in which the diffusion rate of the second process gas is maximum. FIG. 5B shows an example of the mass concentration distribution of the source gas (specifically, trichlorosilane) when the first process gas G1 and the second process gas G2 flow simultaneously in the configuration of FIG. 5A. Dark portions in FIG. 5B indicate regions where the mass concentration of the source gas is relatively low (thus, the mass concentration of the second process gas G2 is relatively high), and light portions indicate that the mass concentration of the source gas is relative Point (ie, the mass concentration of the second process gas G2 is relatively low). The flow direction in which the diffusion rate is maximum coincides with the main flow path F shown in FIGS. 4 and 5A.

Since the main flow path F of the second process gas G2 are spaced away from the periphery W ₀ of the semiconductor wafer W, it is possible to relatively uniformly diffuse mass concentration of the first process gas G1 in the periphery of the semiconductor wafer W . Therefore, it is possible to suppress the formation of the bumps described above when forming the epitaxial layer EP, and also the robustness of the film thickness uniformity control at the time of forming the epitaxial layer against disturbance factors such as the number of rotations of the susceptor. It is possible to improve the

In order to separate the main flow path F of the second process gas G2 from the periphery W ₀ of the semiconductor wafer W is to say the position and releasing direction (nozzle angle of the second outlet 170A to release the second process gas G2 It may be adjusted as appropriate. Whether or not the main channel F are spaced away from the periphery W ₀ of the semiconductor wafer W, it is possible to determine for example by means of numerical analysis employing the finite volume method. Such numerical analysis is performed using, for example, commercially available general-purpose thermal fluid analysis software, etc., with the parameters of the flow rate of the first process gas G1, the release start position and release direction, the flow rate of the second process gas G2, the release start position and release direction The diffusion direction of the first process gas G1 or the second process gas G2 may be dynamically analyzed numerically by setting at least the rotational direction and rotational speed of the susceptor 20, the chamber space, and the wafer surface temperature.

In order to obtain the effects of the present invention more reliably, as shown in FIG. 4, the second gas discharge port 170A, the first gas discharge port 150A, and the discharge port 160 in the rotational direction of the susceptor 20. It is preferable to arrange in the rotational direction upstream between (i.e., −90 degrees <θ ₁ <90 degrees). Furthermore, for this purpose, the second gas discharge port 170A is disposed on the upstream side of the first process gas G1 in the rotational direction of the susceptor 20 (that is, in the x-axis direction, 0 degrees <θ ₁ <90 degrees). Is preferable, and it is more preferable to set 2 degrees <θ ₁ <15 degrees. As a preferred example of θ ₁ , a range of 8 degrees to 12 degrees can be exemplified. At this time, it is preferable to arrange the second gas discharge port 170A by a predetermined distance L from the center of the semiconductor wafer W (that is, the center of the chamber 10) to the upstream side (x axis direction) of the first process gas G1. The predetermined distance L can be about 1/10 to 1/3 of the radius R of the semiconductor wafer W. Then, the direction of the second gas discharge port 170A may be appropriately adjusted according to the distance L by which the position of the second gas discharge port 170A is shifted to the upstream side of the first process gas G1. Specifically, when the radius of the semiconductor wafer is, for example, 150 mm (diameter 300 mm), the position of the second gas discharge port 170A may be shifted to the upstream side of the first process gas G1 by about 15 mm to 50 mm. The distance to be shifted in the y direction is determined correspondingly to the distance L to be shifted in the x direction if it is disposed on the circumference of the chamber.

Further, in order to obtain the main flow path F described above, an angle formed by a first direction from the first gas discharge port 150A toward the discharge port 160 and a discharge direction in which the second process gas is discharged from the second gas discharge port 170A. If θ ₂ is an acute angle, it is more reliable, and in particular, it is more reliable that the angle θ ₂ formed between the first direction and the emission direction is in the range of 40 degrees to 80 degrees, 45 degrees to 55 degrees. It is more certain that it is within the range of degrees. Also, for this purpose, the larger the angle theta ₁ described above, or the distance L increases, it is more reliable Decreasing the angle theta _2.

Furthermore, in order to ensure the effects of the present invention, the peripheral W ₀ of the semiconductor wafer is W, the shortest distance l ₀ and 0mm greater than 40mm or less between the main flow path F of the second process gas G1, further It is preferable to set it as 5 mm or more. If the shortest distance ₁₀ is in this range, the gas flow in the peripheral portion of the semiconductor wafer of the first process gas G1 can be reliably controlled, and the concentration distribution of the source gas can be optimized. Incidentally, the peripheral W _0, and the minimum distance l ₀ between the main flow passage F, means the shortest distance between two different curves.

The above-mentioned arrangement position of the second gas discharge port 170A is only a preferred embodiment, the main flow path F of the gas flow of the second process gas G2 flows onto the susceptor 20, and the main flow path F is a semiconductor wafer As long away from the W rim W ₀ of the arrangement position of the second gas discharge ports 170A it is not limited. Furthermore, as for the relationship between the arrangement position of the second gas discharge port 170A and the susceptor, the arrangement position of the second gas discharge port 170A may be provided such that the main flow path F of the gas flow flows on the susceptor, for example It may be provided to flow on the susceptor from a position equal to or higher than the horizontal position of the susceptor, or vice versa.

  Further, in the epitaxial growth apparatus according to the present embodiment, a silicon wafer is preferably used as the semiconductor wafer W, and the epitaxial layer formed on the silicon wafer is preferably a silicon epitaxial layer. However, the epitaxial growth apparatus according to the present embodiment is also applicable to compound semiconductor wafers and the like, and is also applicable to heteroepitaxial growth.

  Here, the first process gas G1 contains a source gas and a carrier gas as a reaction gas, and in this case, the second process gas G2 preferably comprises a carrier gas. Taking the case of forming a silicon epitaxial layer on a silicon wafer as an example, a silicon source such as dichlorosilane or trichlorosilane can be used as a source gas, and hydrogen can be used as a carrier gas. If the second process gas is the same as the carrier gas of the first process gas, it is preferable in that it does not affect the reaction during epitaxial growth. However, the first and second process gases G1 and G2 used in the present embodiment are not limited to these, and may be appropriately selected according to the substrate type of the semiconductor wafer W and the material of the epitaxial layer. Furthermore, one or both of the first process gas G1 and the second process gas G2 may contain a dopant gas. In the case of forming a silicon epitaxial layer on a silicon wafer, a compound gas containing boron, phosphorus, arsenic or the like can be used.

  Moreover, in order to obtain the above-mentioned main flow path F, the ratio of the gas flow rate of the first process gas G1 to the gas flow rate of the second process gas G2 may be set in the range of 8: 1 to 13: 1. preferable. In addition, the gas flow rate said here refers to the gas flow rate in total amount, when multiple types of different gas are included. That is, when the first process gas G1 contains the source gas and the hydrogen gas, the above ratio may be calculated using the total gas flow rate of them.

  Although the specific aspect of each structure of the epitaxial growth apparatus applicable to this embodiment is demonstrated below, this invention is not limited to these specific aspects at all.

<Chamber>
As shown in FIG. 1, the chamber 10 includes an upper dome 11, a lower dome 12 and a dome attachment 13, and the chamber 10 defines an epitaxial film forming chamber. In the chamber 10, generally, a reaction gas supply port 15A for supplying and discharging a reaction gas _GP and a reaction gas discharge port 16A are provided at opposite positions of the side surface on the upper liner 17 side. Further, the chamber 10, the supply and ambient gas supply port 15B and the ambient gas outlet 16B to perform the discharge of the atmospheric gas G _A at the intersection of the side surface of the lower liner 18 side is provided in general. For simplicity in Figure 1, which illustrates a feed opening and outlet of the reaction gas G _P and the atmospheric gas G _A in the same cross section, and the reactive gas G _P and the atmospheric gas G _A as in Figure 1 parallel There are also cases where a supply port is provided. Also, the dome mounting body 13 is circular like the susceptor and the wafer, and a second nozzle is provided. The dome mount 13 has a diameter of approximately 420 to 470 mm in an epitaxial apparatus for processing a 300 mm wafer.

<Susceptor>
The susceptor 20 is a disk-shaped member on which the semiconductor wafer W is placed inside the chamber 10. The susceptor 20 generally has three through holes vertically penetrating the front and back surfaces at equal intervals of 120 degrees in the circumferential direction. The lift pins 40A, 40B and 40C are respectively inserted into these through holes. The susceptor 20 has a thickness of about 2 to 8 mm and is made of carbon graphite (graphite) as a base material, and the surface thereof is coated with silicon carbide (SiC: Vickers hardness 2,346 kgf / mm ² ) it can. On the surface of the susceptor 20, a counterbore portion (not shown) for accommodating and mounting the semiconductor wafer W is formed.

<Susceptor support shaft>
The susceptor support shaft 30 supports the susceptor 20 from below in the chamber 10, and its support is disposed substantially coaxially with the center of the susceptor 20.

<Lift pin>
The lift pins 40A, 40B and 40C are respectively inserted into the through holes of the susceptor 20. The lift pins 40A, 40B, and 40C are vertically moved by the lift shaft 50 to support the semiconductor wafer W (a rear surface area of a radius of 50% or more) at the upper end of the lift pins. It can be detached on the top. The operation of the elevating shaft will be described later. Similar to the susceptor 20, carbon graphite and / or silicon carbide is generally used as the material of the lift pins 40A, 40B, and 40C.

<Lifting shaft>
The lift shaft 50 defines a hollow housing the main column of the susceptor support shaft 30, and supports the lower end of the lift pin at the tip of the column. The lift shaft 50 is preferably made of quartz. The lift pins 40A, 40B, and 40C can be raised and lowered by the elevating shaft moving up and down along the main column of the susceptor support shaft 30.

<Preheat ring>
The preheat ring 60 covers the side surface of the susceptor 20 via a gap. Is heated by light emitted from a not-shown halogen lamp, the reaction gas G _P flows into the epitaxial film forming chamber, before the reaction gas G _P is in contact with the semiconductor wafer W, the pre-heat ring 60 preheated reaction gas G _P Do. The preheat ring 60 also preheats the susceptor 20. In this way, the preheat ring 60 enhances the thermal uniformity of the susceptor 20 and the semiconductor wafer W before and during film formation. Similar to the susceptor 20, the preheat ring 60 can be made of carbon graphite (graphite) as a base material and the surface thereof is coated with silicon carbide (SiC: Vickers hardness: 2,346 kgf / mm ² ).

<Heating lamp>
The heating lamps are disposed in the upper area and the lower area of the chamber 10, and generally, halogen lamps or infrared lamps, which have high temperature rise and fall speed and excellent temperature controllability, are used.

  Note that hydrogen gas is preferably used as the atmosphere gas introduced into the chamber. As described above, the atmosphere gas is not supplied to the upper surface of the semiconductor wafer W.

(Method of manufacturing semiconductor epitaxial wafer)
Further, in the method of manufacturing a semiconductor epitaxial wafer according to an embodiment of the present invention, the step of mounting the semiconductor wafer on the susceptor of the above-described epitaxial growth apparatus, the first process gas and the second process gas are simultaneously supplied. And vapor phase epitaxial growing an epitaxial layer on the surface of the semiconductor wafer. This manufacturing method can improve the robustness of film thickness uniformity control at the time of forming an epitaxial layer.

  Further, the growth conditions at the time of forming the epitaxial layer on the surface of the semiconductor wafer W can be made general. In the case of forming a silicon epitaxial layer on a silicon wafer, for example, hydrogen is used as a carrier gas, and a source gas such as dichlorosilane or trichlorosilane is introduced into the epitaxial growth furnace by using the source gas as the first process. The growth temperature also varies depending on the temperature, but can be epitaxially grown on the semiconductor wafer by the CVD method at a temperature of about 1000 to 1200 ° C. The second process gas is as described above, and hydrogen is preferably used. The thickness of the epitaxial layer EP to be formed can be in the range of 1 to 15 μm.

  Next, in order to further clarify the effect of the present invention, the following examples are given, but the present invention is not limited to the following examples.

Example 1
The film thickness distribution of the main flow path F of the second process gas G2 and the epitaxial layer formed was numerically analyzed using the epitaxial growth apparatus shown in FIG. 4 when forming a silicon epitaxial layer on the surface of a silicon wafer. The supply port 170A of the second process gas G2, in the upstream side L: is placed in a position of 40 mm, the angle theta ₁ is 10 degrees, the angle theta ₂ was 50 degrees.

In Example 1, trichlorosilane (TCS) and hydrogen gas were introduced as the first process gas G1, and hydrogen gas was introduced as the second process gas G2. The total flow rate of the first process gas G1 was 84 slm (H ₂ : 75 slm, TCS: 9 slm), and the flow rate of the second process gas G 2 was 7 slm. The susceptor rotational speed was 70 rpm, and the wafer temperature on the susceptor was 1130 ° C.

  In the numerical analysis of the mass concentration distribution of the first process gas, the mass concentration distribution of TCS is calculated, and the flow rate of the first process gas G1, the release start position and the release direction, the flow rate of the second process gas G2, the release start point as parameters The position and discharge direction, the rotation direction and rotation number of the susceptor 20, the chamber space, the wafer surface temperature, and the pressure in the furnace (normal pressure) were set. Then, the main flow path F was obtained from the obtained mass concentration distribution. In addition, as a numerical analysis of the epitaxial growth process, TCS was used as a silicon source, and the epitaxial growth rate distribution was determined.

The main flow path F by the numerical analysis result is shown in figure to FIG. 6A. As shown in FIG. 6A, the main flow path F is always separated from the peripheral edge Wo of the silicon wafer. In the above numerical analysis, the shortest distance ₁₀ was 25 mm. The calculation result of the film thickness distribution in the wafer peripheral part of the epitaxial layer obtained in this case is shown to FIG. 7A. From FIG. 7A, it can be confirmed that the epitaxial film thickness is rolled up only.

(Comparative example 1)
The configuration of FIG. 3, that is, the direction of the supply port 170A of the second process gas G2 is directed to the center of the wafer, and the moving distance on the upstream side of the first process gas G1 is 0 (zero), Example 1 Similarly to the above, the thickness distribution of the main flow path F and the formed epitaxial layer was numerically analyzed.

  The results according to Comparative Example 1 are shown in FIGS. 6B and 7B in the same manner as Example 1. From FIG. 6B, it can be confirmed that the main flow path F flows into the semiconductor wafer W in the first comparative example. Then, as shown in FIG. 7B, it can be confirmed that a bump of the epitaxial layer at the wafer peripheral portion called a bump (that is rolled off after rolling up) is formed.

  Furthermore, in Example 1 and Comparative Example 1, the susceptor rotational speed 70 rpm and the distribution ratio of the first process gas were set to 5: 1 as the condition 1 (condition 1). The susceptor rotational speed 32 rpm, the distribution ratio of the first process gas 1: Numerical analysis was performed even in the case of 1 (condition 2). Furthermore, when the flow rate of the second process gas is 3 slm, 5 slm, and 7 slm under each of the conditions 1 and 2, the thickness difference of the epitaxial layer between the positions of 140 mm and 148 mm in the radial direction is shown in FIG. And FIG. 8B (comparative example 1).

  From FIGS. 8A and 8B, in Comparative Example 1, it is confirmed that the response of the outer peripheral film thickness of the epitaxial wafer is not monotonically increasing with the increase of the flow rate of the hydrogen gas of the second process gas, and the noise influence is large. On the other hand, in Example 1, it was confirmed that the response of the outer peripheral film thickness of the epitaxial wafer was monotonously increased with the increase of the flow rate of the hydrogen gas of the second process gas. It was confirmed that it could be improved.

  According to the present invention, it is possible to provide an epitaxial growth apparatus capable of improving the robustness of film thickness uniformity control at the time of forming an epitaxial layer.

DESCRIPTION OF SYMBOLS 100 epitaxial growth apparatus 10 chamber 11 upper dome 12 lower dome 13 dome attachment body 15A reaction gas supply port 15B atmosphere gas supply port 16A reaction gas outlet 16B atmosphere gas outlet 17 upper liner 18 lower liner 20 susceptor 30 susceptor support shaft 40A, 40C Lift pin 50 Lifting shaft 60 Preheat ring 150 First gas supply unit 150A First gas discharge port 160 Discharge port 170 Second gas supply unit 170A Second gas discharge port G1 First process gas G2 Second process gas F Main flow path W Semiconductor wafer

Further, in the chamber 10, a susceptor 20 on which the semiconductor wafer W is mounted is disposed. The susceptor 20 is supported by the susceptor support shaft 30 from below. The susceptor support shaft 30 engages and supports the lower surface outer peripheral portion of the susceptor 20 with three support pins (not shown) at the tip of the arm. Furthermore, three through holes (one of which is not shown) are formed in the susceptor 20, and one through hole is also formed in the arm of the susceptor support shaft 30. The lift pins 40A, 40B, and 40C (however, the lift pins 40B are not shown in the schematic cross-sectional view of FIG. 1) are inserted through the through holes of the arms and the through holes of the susceptor. Further, the lower end portion of the lift pin 40 is supported by the lift shaft 50. When supporting the semiconductor wafer W carried into the chamber 10, mounting the semiconductor wafer W on the susceptor 20, and unloading the epitaxial wafer after vapor phase epitaxial growth out of the chamber 10 , a lift shaft by 50 is raised and lowered, the lift pin 40 moves up and down with the through hole and the sliding of the through hole and the susceptor arm, performs lifting of the semiconductor wafer W at its upper end. When forming the epitaxial layer EP using the single wafer type epitaxial growth apparatus 900, the reaction gas _GP is brought into contact with the upper surface of the semiconductor wafer W mounted on the susceptor 20 while rotating the susceptor 20. Further, the reaction gas G _p, means a gas obtained by mixing a source gas to the carrier gas. When forming a silicon epitaxial layer as the epitaxial layer EP, a silicon source gas such as trichlorosilane gas is used as a source gas. The side surface of the susceptor 20 is generally covered by the preheat ring 60 via a gap of about 3 mm.

That is, the gist configuration of the present invention is as follows.
(1) An epitaxial growth apparatus for vapor phase epitaxial growth of an epitaxial layer on the surface of a semiconductor wafer, comprising:
A chamber,
A susceptor for mounting the semiconductor wafer inside the chamber;
A first gas supply unit for supplying a first process gas to a top surface of the semiconductor wafer, the first gas discharge port releasing a first process gas containing a reaction gas for vapor phase epitaxial growth of the epitaxial layer;
A second gas discharge port for releasing a second process gas for controlling a gas flow of the first process gas at the peripheral portion of the semiconductor wafer, and a second process gas is supplied toward the upper surface of the semiconductor wafer A gas supply unit,
Have
The main flow path of the gas flow of the second process gas when simultaneously supplying the first and second process gas flows onto the susceptor, and the main flow path is separated from the periphery of the semiconductor wafer. An epitaxial growth apparatus characterized in that a second gas supply unit is disposed.

Further, the growth conditions at the time of forming the epitaxial layer on the surface of the semiconductor wafer W can be made general. In the case of forming a silicon epitaxial layer on a silicon wafer, for example, hydrogen as a carrier gas, dichlorosilane, a source gas such as trichlorosilane in the first process gas is introduced into the epitaxial growth furnace, the source to be used Although the growth temperature also differs depending on the gas, it can be epitaxially grown on the semiconductor wafer by the CVD method at a temperature in the range of about 1000 to 1200 ° C. The second process gas is as described above, and hydrogen is preferably used. The thickness of the epitaxial layer EP to be formed can be in the range of 1 to 15 μm.

Claims (8)

An epitaxial growth apparatus for vapor phase epitaxial growth of an epitaxial layer on a surface of a semiconductor wafer, comprising:
A chamber,
A susceptor for mounting the semiconductor wafer inside the chamber;
A first gas supply unit for supplying a first process gas to a top surface of the semiconductor wafer, comprising: a first discharge port for releasing a first process gas containing a reaction gas for vapor phase epitaxial growth of the epitaxial layer;
A second gas supply port for discharging a second process gas for controlling the gas flow of the first process gas at the peripheral portion of the semiconductor wafer, and a second gas for supplying the second process gas in the direction of the upper surface of the semiconductor wafer The supply department,
Have
The main flow path of the gas flow of the second process gas when simultaneously supplying the first and second process gas flows onto the susceptor, and the main flow path is separated from the periphery of the semiconductor wafer. An epitaxial growth apparatus characterized in that a second gas supply unit is disposed. The epitaxial growth apparatus has a discharge port for discharging the first process gas at a position facing the first gas discharge port,
The epitaxial growth apparatus according to claim 1, wherein the second gas discharge port is disposed upstream of the first gas discharge port and the discharge port in the rotational direction of the susceptor.   The epitaxial growth apparatus according to claim 2, wherein the second gas discharge port is disposed upstream of the first process gas in the rotational direction of the susceptor.   The angle between the first direction from the first gas discharge port to the discharge port and the discharge direction from which the second process gas is discharged from the second gas discharge port is an acute angle. The epitaxial growth apparatus described in.   The epitaxial growth apparatus according to claim 4, wherein an angle formed by the first direction and the emission direction is in a range of 40 degrees to 80 degrees. The first process gas includes a source gas and a carrier gas,
The epitaxial growth apparatus according to any one of claims 1 to 5, wherein the second process gas comprises the carrier gas.   The epitaxial growth apparatus according to any one of claims 1 to 6, wherein a shortest distance between a peripheral edge of the semiconductor wafer and the main flow channel of the second process gas is 5 mm or more and 40 mm or less. A step of mounting a semiconductor wafer on the susceptor of the epitaxial growth apparatus according to any one of claims 1 to 7.
And d) simultaneously supplying the first process gas and the second process gas to vapor-phase epitaxially grow an epitaxial layer on the surface of the semiconductor wafer.