JP3731550B2 - Method for manufacturing silicon wafer and method for manufacturing silicon epitaxial wafer - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for manufacturing a silicon wafer and a method for manufacturing a silicon epitaxial wafer.
[0002]
[Prior art]
Conventionally, for example, a source gas is supplied onto the main surface of a silicon single crystal substrate (hereinafter also simply referred to as a silicon substrate) to thereby form a silicon epitaxial layer (hereinafter also simply referred to as an epitaxial layer) on the main surface. There is a known method for producing a silicon wafer by vapor-phase-growing a silicon thin film on the main surface of a silicon substrate, such as producing a silicon epitaxial wafer (hereinafter also simply referred to as an epitaxial wafer) by vapor-phase-growing the substrate. It has been.
In this vapor phase growth, for example, the silicon substrate is placed on a substantially disc-shaped susceptor so that the main surface thereof is directed upward, and the silicon substrate is rotated along with the rotation of the susceptor in the plate surface direction. Also, the raw material gas is supplied onto the main surface of the silicon substrate while rotating in the plate surface direction.
[0003]
[Problems to be solved by the invention]
Here, the film thickness of the silicon thin film (for example, epitaxial layer) of the silicon wafer (for example, epitaxial wafer) obtained by vapor phase growth has a correlation with the amount of the source gas supplied.
For this reason, conventionally, as described above, in addition to rotating the silicon substrate at the time of vapor phase growth, it is possible to set a difference in the flow rate of the raw material gas supplied between the central portion and the peripheral portion of the silicon substrate. There are cases where measures such as adjusting the thickness distribution are taken.
However, even if such measures are taken, for example, an annular distribution may occur in the film thickness of the silicon thin film.
[0004]
The present invention has been made in order to solve the above-described problems, and silicon that can make the film thickness distribution of a silicon thin film (e.g., epitaxial layer) of a silicon wafer (e.g., epitaxial wafer) more uniform. An object of the present invention is to provide a method for producing a wafer and a method for producing a silicon epitaxial wafer.
[0005]
[Means for Solving the Problems]
In order to solve the above problems, the silicon wafer manufacturing method of the present invention is substantially parallel to the main surface of the silicon single crystal substrate while rotating the silicon single crystal substrate arranged in a substantially horizontal state in the plate surface direction. in by supplying raw material gas, the method for producing a silicon wafer for a silicon thin film vapor phase growth on the major surface, by changing the path of the material gas in the vapor phase growth, of the silicon single crystal substrate It is characterized in that the position where the growth rate of the silicon thin film is large is changed on the main surface .
That is, by changing the path of the source gas during the vapor phase growth in a plane parallel to the plate surface of the silicon single crystal substrate, a position where the growth rate of the silicon thin film is high on the main surface of the silicon single crystal substrate. It is characterized by changing .
[0006]
More specifically, the silicon thin film to be vapor-grown on the main surface of the silicon single crystal substrate in the present invention includes, for example, a silicon epitaxial layer. Therefore, in this case, the silicon wafer manufactured by vapor-phase growth is It becomes a silicon epitaxial wafer.
That is, the present invention provides the main surface by supplying the source gas substantially parallel to the main surface of the silicon single crystal substrate while rotating the silicon single crystal substrate arranged in a substantially horizontal state in the plate surface direction. In a silicon epitaxial wafer manufacturing method for producing a silicon epitaxial wafer by vapor-phase-growing a silicon epitaxial layer on the main surface of the silicon single crystal substrate by changing a course of a source gas during the vapor-phase growth It is a preferable example that the position where the growth rate of the silicon epitaxial layer is high is changed .
The present invention is not limited to this. For example, a silicon wafer is manufactured by vapor-phase growth of a polycrystalline thin film, a nitride, or an oxide silicon thin film on the main surface of a silicon single crystal substrate. You may apply when you do.
[0007]
Moreover, it is preferable to change the course of the source gas by changing the rotational speed of the silicon single crystal substrate, for example.
In this case, more specifically, the rotational speed may be changed so that the period for performing vapor phase growth includes a plurality of periods with different rotational speeds of the silicon single crystal substrate, or During the vapor phase growth, the rotation speed of the silicon single crystal substrate may be gradually changed.
The source gas path can be changed, for example, by changing the direction of the source gas introduction path (for example, constituted by a nozzle) within a plane parallel to the plate surface direction of the silicon single crystal substrate. May be performed. In addition, the path of the source gas may be changed, for example, by moving the susceptor in a direction intersecting the source gas flow in a plane parallel to the plate surface direction of the silicon single crystal substrate. .
In addition, the course of the source gas may be changed by, for example, changing the carrier gas flow rate. That is, when the carrier gas flow rate is large, the flow rate of the vapor phase growth gas including the carrier gas and the source gas increases, and therefore the course of the vapor phase growth gas is influenced by the rotation of the silicon substrate. It becomes difficult to receive. On the other hand, when the carrier gas flow rate is small, the flow rate of the vapor phase growth gas is small, and therefore the course of the vapor phase growth gas is easily affected by the rotation of the silicon substrate (the rotation of the silicon substrate). Easier to be dragged in the direction). Therefore, the course of the source gas can be changed as the carrier gas flow rate is increased or decreased.
[0008]
According to the present invention, by changing the path of the material gas in the vapor deposition, on a main surface of a silicon single crystal substrate, by changing the position greater growth rate of the silicon thin film (e.g., silicon epitaxial layer) because , it can be more uniform thickness of the silicon thin film.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
In the present embodiment, an example in which a so-called single wafer type vapor phase growth apparatus is applied as a vapor phase growth apparatus for carrying out the method for producing a silicon epitaxial wafer according to the present invention will be described.
[0010]
First, a single wafer type vapor phase growth apparatus 1 will be described with reference to FIG.
As shown in FIG. 1, a vapor phase growth apparatus 1 includes a reaction vessel 3 in which a silicon single crystal substrate 2 (hereinafter also simply referred to as a silicon substrate 2) is disposed during vapor phase growth, and the reaction vessel. 3, a substantially disc-shaped susceptor 4 which is arranged in a substantially horizontal state and on which the silicon substrate 2 is mounted, and a source gas (for example, trichlorosilane) and a carrier gas (for example, hydrogen gas) are introduced into the reaction vessel 3. An introduction path 5 for introducing the vapor phase growth gas to be included and an exhaust path 6 for exhausting the gas from the reaction vessel 3 are provided.
In addition, the vapor phase growth apparatus 1 includes a heating device (not shown) for heating the silicon substrate 2 on the susceptor 4 in the reaction vessel 3 to a desired temperature, and the susceptor 4 on the plate during the vapor phase growth. Along with the rotation in the surface direction, the silicon substrate 2 is also provided with a driving device 7 for rotating in the plate surface direction. The driving device 7 is configured to be able to change the rotational speed of the susceptor 4 (and hence the rotational speed of the silicon substrate 2).
[0011]
In the present embodiment, vapor phase growth is performed as described below, using the vapor phase growth apparatus 1 configured as described above.
[0012]
First, the silicon substrate 2 is placed on the susceptor 4 in the reaction vessel 3 so that the main surface thereof is directed upward. That is, the silicon substrate 2 is arranged in a substantially horizontal state.
Next, the silicon substrate 2 is heated to a desired temperature (for example, 1100 ° C.) in the supply rate-determining region by a heating device and rotated in the plate surface direction, and the vapor growth gas is supplied to the silicon substrate through the introduction path 5. The silicon epitaxial layer (hereinafter also simply referred to as “epitaxial layer”) is vapor-phase grown on the main surface by supplying substantially parallel to the two main surfaces.
In the present embodiment, the silicon substrate 2 is rotated at a low speed (for example, 10 rotations / minute) in the first half, and at a high speed (for example, 35 rotations / minute) in the second half, for example, during this vapor phase growth (see FIG. 2 (b)).
The total length of the vapor phase growth period can be determined in advance based on the film thickness of the epitaxial layer that needs to be vapor phase grown. The other half may be a period for rotating at high speed.
[0013]
Here, referring to FIG. 5, vapor phase growth gas (raw material gas is introduced into reaction vessel 3 from introduction path 5 in the direction of arrow A and supplied onto the main surface of silicon substrate 2 on susceptor 4. Including the flow).
As shown in FIG. 5, when the rotation speed of the silicon substrate 2 (and the susceptor 4) is low (for example, 10 rotations / minute), the course of the gas flow for vapor deposition on the main surface of the silicon substrate 2 is It is hardly affected by the rotation of the silicon substrate 2 (and the susceptor 4). For this reason, the gas flow for vapor phase growth becomes a course along the direction of arrow C which is substantially the same as the direction of arrow A even on the main surface of silicon substrate 2.
On the other hand, when the rotation speed of the silicon substrate 2 (and the susceptor 4) is high (for example, 35 rotations / minute), the path of the gas phase growth gas flow on the main surface of the silicon substrate 2 is the silicon substrate 2. (And susceptor 4) are greatly affected by the rotation.
Specifically, for example, if the rotation direction of the silicon substrate 2 (and the susceptor 4) is clockwise (in the direction of arrow B in FIG. 5) in a plan view, the vapor phase when the rotation speed is the above high speed. The path of the growth gas flow changes as compared with the arrow C as shown by the arrow D in FIG.
This is because on the main surface of the silicon substrate 2, the course of the gas flow for vapor phase growth is changed by being dragged by the rotating silicon substrate 2 and the susceptor 4 (specifically, for example, the upstream portion ( In the part E of FIG. 5, the course changes away from the arrow C, and in the downstream part (F part of FIG. 5), the course changes so as to approach the arrow C).
[0014]
For example, as shown in FIG. 3B or FIG. 4B, when the epitaxial wafer is manufactured by setting the rotation speed of the silicon substrate 2 to be constant throughout the vapor phase growth period, As shown in FIG. 3A or 4A, an annular distribution occurs in the film thickness of the epitaxial layer.
Specifically, when the rotation speed of the silicon substrate 2 is set to, for example, 10 rotations / minute (low speed), the film thickness of the epitaxial layer is such that the central portion and the peripheral portion are as shown in FIG. It is large and becomes small between the central part and the peripheral part.
On the other hand, when the rotation speed of the silicon substrate 2 is set to 35 rotations / minute (high speed), for example, the film thickness of the epitaxial layer is small at the center as shown in FIG. Larger at the both sides, smaller at both sides, and larger again at the periphery.
Here, when the rotational speed of the silicon substrate 2 is constant throughout the vapor phase growth period, it is the same in that the uniformity of the thickness of the epitaxial layer is not good in any case. It can be seen that the film thickness depending on the position of the epitaxial wafer in the diameter direction differs depending on the rotation speed of the silicon substrate 2 (for example, when the rotation speed of the silicon substrate 2 is the low speed, the film thickness is in the center portion). (In contrast, it is small at the center in the case of the above high speed.)
[0015]
On the other hand, as in the present embodiment, the silicon substrate 2 is rotated at a low speed (for example, 10 rotations / minute) in the first half of the period for performing vapor phase growth and at a high speed (for example, 35 rotations / minute) in the second half. For example, as shown in FIG. 2A, a film thickness distribution is obtained by synthesizing the film thicknesses of FIG. 3A and FIG. 4A, and either of FIG. 3A or FIG. Compared to the case, the film thickness distribution of the epitaxial layer is made uniform.
This is because the path of the source gas (vapor phase growth gas) can be changed in accordance with the change in the rotation speed of the silicon substrate 2, and as a result, the growth rate of the epitaxial layer is high on the main surface of the silicon substrate 2. This is because the position can be changed.
Therefore, by changing the rotational speed of the silicon substrate 2 during the vapor phase growth as in the present embodiment, the growth amount of the epitaxial layer on the main surface of the silicon substrate 2 is reduced over the entire period of the vapor phase growth. , The entire main surface can be made uniform. As a result, the film thickness distribution of the epitaxial layer in the epitaxial wafer can be made uniform.
[0016]
In the above-described embodiment, the example in which the period during which the vapor phase growth is performed includes two periods in which the rotational speed of the silicon substrate is low and high is described. However, three or more different rotational speeds of the silicon substrate are different from each other. In this case, the thickness of the epitaxial layer can be made uniform.
Furthermore, as described above, the period during which the vapor phase growth is performed is not limited to an example in which the rotation speed of the silicon substrate is different from each other, and the rotation speed of the silicon substrate is gradually changed during the period during which the vapor phase growth is performed. In this case, the thickness of the epitaxial layer can be made even more uniform.
In this case, the rotational speed of the silicon substrate may be gradually changed from a low speed to a high speed (or from a high speed to a low speed), or after gradually changing from a low speed to a high speed, the speed gradually decreases again. (Or after gradually changing from high speed to low speed, it may be changed gradually to high speed again).
In short, in consideration of factors caused by the vapor phase growth apparatus, the mode of changing the rotation speed of the silicon substrate may be appropriately set so that the film thickness becomes more uniform.
[0017]
In the above description, the example of changing the path of the source gas by changing the rotation speed of the silicon substrate has been described. However, the present invention is not limited thereto, and the source gas introduction path 5 (for example, constituted by a nozzle) is used. The course of the source gas may be changed by changing the direction in a plane parallel to the plate surface direction of the silicon substrate.
In this case, specifically, for example, via a drive transmission member (configured by a gear or the like) that converts motor driving into oscillation of the introduction path 5 in a plane parallel to the plate surface direction of the silicon substrate. And transmitting to the introduction path 5.
Alternatively, the susceptor may be moved by moving it in a direction crossing (for example, substantially orthogonal to) the raw material gas flow in a plane parallel to the plate surface direction of the silicon substrate. Also in this case, for example, the motor drive may be converted and transmitted by the drive transmission member.
[0018]
In the above description, an example in which the present invention is applied when vapor phase growth is performed using a single wafer type vapor phase growth apparatus has been described, but the present invention is not limited thereto.
For example, as in a pancake-type vapor phase growth apparatus, silicon substrates are placed in substantially horizontal positions at different positions on the upper surface of a substantially disc-shaped susceptor, and the susceptor is rotated in the direction of the plate surface. By rotating the silicon substrate in the direction of the plate surface and supplying the source gas substantially parallel to the main surface of these silicon substrates, vapor phase growth is performed on these multiple silicon substrates at once, The present invention may be applied to a multi-stage vapor phase growth apparatus that manufactures a large number of epitaxial wafers at a time.
In this case, in addition to the same effect as the above case, the difference in the amount of source gas supplied between silicon substrates that perform vapor phase growth at one time can be reduced, so that epitaxial wafers manufactured at one time can be epitaxially grown. The layer thickness can be made uniform.
[0019]
In the above description, the example in which the present invention is applied to the case where an epitaxial wafer is manufactured by vapor-phase growth of an epitaxial layer on the main surface of the silicon single crystal substrate has been described. When a silicon wafer is manufactured by vapor-phase growth of a silicon thin film of either a silicon polycrystalline thin film (polycrystalline thin film), silicon nitride (nitride), or silicon oxide (oxide) on the main surface of It may be applied.
[0020]
【The invention's effect】
According to the method for producing a silicon wafer and the method for producing a silicon epitaxial wafer of the present invention, a silicon thin film (for example, silicon epitaxial) is formed on the main surface of the silicon single crystal substrate by changing the path of the source gas during vapor phase growth. Runode to change the position greater growth rate of the layer), the total period for vapor-phase growth, the growth amount of the silicon thin film on the main surface of a silicon single crystal substrate, it made more uniform across the main surface it can. As a result, the film thickness distribution of the silicon thin film can be made more uniform.
[Brief description of the drawings]
FIG. 1 is a schematic front sectional view showing a preferred example of a vapor phase growth apparatus used in an embodiment according to the present invention.
FIG. 2A is a diagram showing an example of a film thickness distribution when the rotational speed of a silicon single crystal substrate is changed during vapor phase growth, and FIG. 2B shows how the rotational speed is changed in this case. FIG.
3A is a diagram showing an example of a film thickness distribution when the rotational speed of a silicon single crystal substrate during vapor phase growth is constant, and FIG. 3B is a diagram showing the rotational speed in this case. .
FIG. 4 is a diagram showing another example of the film thickness distribution when the rotational speed of the silicon single crystal substrate during vapor phase growth is constant, and (b) is a diagram showing the rotational speed in this case.
FIG. 5 is a schematic plan view for explaining a change mode of the raw material gas flow according to the rotation speed of the silicon single crystal substrate.
[Explanation of symbols]
2 Silicon single crystal substrate

Claims (5)

A silicon thin film is formed on the main surface by supplying a source gas substantially parallel to the main surface of the silicon single crystal substrate while rotating the silicon single crystal substrate arranged in a substantially horizontal state in the plate surface direction. In the method for producing a silicon wafer to be vapor-grown, by changing the path of the source gas during the vapor-phase growth, the position where the growth rate of the silicon thin film is large is changed on the main surface of the silicon single crystal substrate. A method for producing a silicon wafer. 2. The method for producing a silicon wafer according to claim 1, wherein the path of the source gas is changed by changing a rotation speed of the silicon single crystal substrate. 3. The method for manufacturing a silicon wafer according to claim 2, wherein the period for performing the vapor phase growth includes a plurality of periods in which rotation speeds of the silicon single crystal substrate are different from each other. 3. The method of manufacturing a silicon wafer according to claim 2, wherein the rotation speed of the silicon single crystal substrate is gradually changed during the vapor phase growth. A silicon epitaxial layer is formed on the main surface by supplying a source gas substantially parallel to the main surface of the silicon single crystal substrate while rotating the silicon single crystal substrate arranged in a substantially horizontal state in the plate surface direction. In the silicon epitaxial wafer manufacturing method for producing a silicon epitaxial wafer by vapor phase growth , a silicon epitaxial layer is formed on the main surface of the silicon single crystal substrate by changing the path of the source gas during the vapor phase growth. A method for producing a silicon epitaxial wafer, wherein the position at which the growth rate of silicon is high is changed .

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