JP5184302B2 - Susceptor device, epitaxial wafer manufacturing apparatus, and epitaxial wafer manufacturing method - Google Patents

Description

  The present invention relates to a susceptor device, an epitaxial wafer manufacturing apparatus, and an epitaxial wafer manufacturing method.

Conventionally, a method of manufacturing an epitaxial wafer by vapor-phase growth of an epitaxial film on the surface of the wafer is known (see, for example, Patent Document 1).
This Patent Document 1 discloses a configuration in which a susceptor is supported at three points from the back side by a quartz support shaft. Above and below the susceptor supported by the support shaft, there is provided a heating device that is composed of a halogen lamp or the like and heats the susceptor and the wafer with radiant heat.

JP 2000-269137 A

However, in the configuration of Patent Document 1, since only the peripheral edge of the non-mounting surface of the susceptor is supported by the support shaft, the radiation light from the front, rear, left and right heating devices concentrates on the center of the non-mounting surface of the susceptor. The temperature of the portion corresponding to the center of the epitaxial wafer (meaning only one point at the center) and the vicinity thereof (hereinafter referred to as the susceptor center-corresponding portion) will be higher than the surrounding portions. As a result, the thickness of the epitaxial film at the center of the epitaxial wafer (hereinafter referred to as the epi-center thickness as appropriate) becomes extremely thick compared to the surrounding portion. In other words, the film thickness variation (hereinafter referred to as the center) of the central portion of the epitaxial wafer (meaning a substantially circular portion having a diameter of about A / 2 centered on the center of the epitaxial wafer when the diameter of the epitaxial wafer is A). (Referred to as part thickness variation).
In order to reduce such film thickness variation in the central portion, it is conceivable to greatly reduce the amount of reaction gas used for vapor phase growth of the epitaxial film.
However, if the amount of the reaction gas is greatly reduced, the film thickness variation in the central portion is improved, but abnormal growth occurs on the back surface of the epitaxial wafer, and there is a problem that the nanotopography is deteriorated.

  An object of the present invention is to provide a susceptor device, an epitaxial wafer manufacturing apparatus, and an epitaxial wafer manufacturing method capable of reducing variations in the thickness of the epitaxial film without causing abnormal growth on the back surface of the epitaxial wafer. .

  The susceptor device of the present invention manufactures an epitaxial wafer by vapor-phase growth of an epitaxial film on the film-forming surface while irradiating radiation from the back side opposite to the film-forming surface of the wafer and heating the wafer. A susceptor device provided in an epitaxial wafer manufacturing apparatus for holding the wafer, the susceptor having a mounting surface on which the wafer is mounted, peripheral support means for supporting the vicinity of the periphery of the susceptor, and the wafer Temperature control means for controlling the temperature of a portion of the susceptor corresponding to the center of the wafer when the susceptor is placed, and the temperature control means is formed in a substantially rod shape and is opposite to the placement surface. It extends in a direction substantially orthogonal to the non-mounting surface on the non-mounting surface side, and the end on the non-mounting surface side is close without contacting the portion corresponding to the center of the wafer on the non-mounting surface. Characterized in that provided in a state that.

According to the present invention, the substantially bar-shaped temperature control means provided on the non-mounting surface side of the susceptor shields the emitted radiation light, so that the susceptor center-corresponding portion can be compared with the configuration without the temperature control means. The temperature can be lowered.
Here, when the non-mounting surface of the susceptor and the end portion of the temperature control means are brought into surface contact, the portion in contact with the surface is absorbed by the temperature control means, and locally compared to other parts. It will be lower. For this reason, there exists a possibility that epi center film thickness may become thin locally compared with the circumference | surroundings.
On the other hand, in the present invention, since the end of the temperature control means is brought close to the non-mounting surface susceptor center corresponding portion, the endothermic action of the susceptor center corresponding portion due to contact does not occur. , Local temperature drop can be suppressed.
Therefore, the temperature of the susceptor center-corresponding portion can be appropriately reduced, and an epitaxial film having a small thickness variation in the center portion can be vapor-phase grown without greatly reducing the amount of the reaction gas. In addition, since it is not necessary to reduce the reaction gas in order to reduce the film thickness variation in the central portion, it is possible to prevent abnormal growth from occurring on the back surface of the epitaxial wafer.
When the center of the susceptor coincides with the center of the wafer placed on the susceptor, the susceptor center corresponding portion is a portion centered on the center of the susceptor. For this reason, a temperature control means is provided in the state which the edge part adjoins to the center of a non-mounting surface. Further, when the center of the susceptor and the center of the wafer placed on the susceptor do not coincide with each other, the susceptor center-corresponding portion is a portion centered on a position shifted from the center of the susceptor. For this reason, a temperature control means is provided in the state which adjoins the position from which the edge part shifted | deviated from the center of the non-mounting surface.

In the susceptor device of the present invention, it is preferable that the distance between the end portion on the non-mounting surface side of the temperature control means and the non-mounting surface is set to 4 mm or more and 20 mm or less.
Here, when the distance between the end portion of the temperature control means and the non-mounting surface of the susceptor (hereinafter referred to as a temperature control separation distance) is shorter than 4 mm, the susceptor becomes the temperature control means because they are too close to each other. There is a risk of significant heat absorption. For this reason, compared with the case where it is made longer than 4 mm, a local temperature fall will arise and there exists a possibility that epi center film thickness may become thin locally compared with the circumference | surroundings. On the other hand, when the temperature control separation distance is longer than 20 mm, the light shielding effect of the radiation light irradiated on the non-mounting surface may be reduced. For this reason, similarly to the configuration without the temperature control means, the temperature of the susceptor center-corresponding portion becomes higher than the other portions, and there is a risk that the thickness variation in the center portion cannot be reduced without causing abnormal growth on the back surface of the epitaxial wafer. There is.
On the other hand, in the present invention, since the temperature control separation distance is set to 4 mm or more and 20 mm or less, the thickness variation in the central portion can be reduced without causing the above-described problems.

In the susceptor device according to the present invention, it is preferable that the temperature control means is processed so that the surface reflects the radiation light.
In the susceptor device of the present invention, it is preferable that the temperature control means is formed of an opaque member.
Here, when the temperature control means is provided with a function to transmit the radiant light as it is without regular reflection or irregular reflection, even when it is made of a transparent member such as quartz, the radiation is compared with the structure without the temperature control means. Although a light blocking effect can be obtained, the effect is reduced as compared with the case where the temperature control means has a function of reflecting in advance or the temperature control means is formed of an opaque member. For this reason, by providing the temperature control means with a function of reflecting the radiant light, a sufficient light shielding effect can be obtained and the film thickness variation in the central portion can be reduced.

In the susceptor device of the present invention, it is preferable that the temperature control means is detachably attached to the peripheral edge support means.
According to the present invention, since the temperature control means is detachably attached to the peripheral support means, the temperature control means can be easily made before the temperature control means is etched with the corrosive gas and the length or thickness changes greatly. Exchangeable and stable quality epitaxial wafers can be manufactured.

In the susceptor device of the present invention, it is preferable that the diameter of the temperature control means is set to 3.0 mm or more and 22.0 mm or less.
Here, when the diameter of the temperature control means is set to 3.0 mm, the variation in film thickness at the central portion in an epitaxial wafer having a diameter of 200 mm that is generally large in production can be reduced, and when the diameter is set to 22 mm, the production is generally reduced. Variations in film thickness at the center of an epitaxial wafer having a large diameter of 300 mm can be reduced.

  An epitaxial wafer manufacturing apparatus according to the present invention is an epitaxial wafer manufacturing apparatus for manufacturing an epitaxial wafer by vapor-phase growth of an epitaxial film on a film forming surface of the wafer, the susceptor apparatus described above holding the wafer, This susceptor device is installed inside, and a reaction vessel capable of supplying a reaction gas for vapor-phase growth of an epitaxial film on the film formation surface of the wafer, and a back side opposite to the film formation surface of the wafer And a back side light emission heating means for heating the wafer by irradiating radiation light from the surface.

  In the epitaxial wafer manufacturing method of the present invention, the wafer is held by a susceptor device that holds the wafer, and the wafer is heated while being irradiated with radiation light from the back side opposite to the film forming surface of the wafer. An epitaxial wafer manufacturing method for manufacturing an epitaxial wafer by supplying a reactive gas and vapor-phase-growing an epitaxial film on the film-forming surface, wherein the susceptor device includes a mounting surface on which the wafer is mounted. A susceptor having, a peripheral support means for supporting the vicinity of the peripheral edge of the susceptor, and a temperature control means for controlling the temperature of a portion corresponding to the center of the wafer in the susceptor when the wafer is placed, The temperature control means is formed in a substantially rod shape, extends in a direction substantially orthogonal to the non-mounting surface on the non-mounting surface side opposite to the mounting surface, and The mounting surface side end portion is provided in a state of being close to the non-mounting surface corresponding to the center of the wafer without being in contact therewith, and by shielding the radiation light by the temperature control means, The temperature of the portion corresponding to the center of the wafer in the susceptor is controlled.

  According to the above invention, by providing the manufacturing apparatus with the same configuration as the susceptor apparatus described above, the epitaxial wafer manufacturing apparatus and manufacturing that can reduce the film thickness variation in the central portion without causing abnormal growth on the back surface of the epitaxial wafer. Can provide a method.

An embodiment of the present invention will be described with reference to the drawings.
[Configuration of epitaxial wafer manufacturing equipment]
First, the configuration of an epitaxial wafer manufacturing apparatus will be described.
FIG. 1 is a cross-sectional view showing a main part of an epitaxial wafer manufacturing apparatus. FIG. 2 is a plan view of the epitaxial wafer manufacturing apparatus.
As shown in FIG. 1, the epitaxial wafer manufacturing apparatus 1 manufactures an epitaxial wafer WE by vapor-phase-growing an epitaxial film E on a film-forming surface W1 of a wafer W obtained by processing a semiconductor crystal into a plate shape. As shown in FIGS. 1 and 2, the manufacturing apparatus 1 includes a reaction vessel 2, a susceptor device 3, and a heating unit 4.

The reaction vessel 2 has a susceptor device 3 installed therein, and is configured to be able to supply reaction gas and purge gas therein. Then, by supplying the reaction gas to the wafer W placed on the susceptor device 3, the epitaxial film E is vapor-phase grown on the film formation surface W <b> 1 of the wafer W. The reaction vessel 2 includes an upper chamber member 21 and a lower chamber member 22.
Although not shown in detail, the upper chamber member 21 and the lower chamber member 22 are formed in a substantially concave shape in which a central portion in a plan view is depressed by combining a plurality of translucent members such as quartz. Then, the reaction chamber 2A is formed inside the reaction vessel 2 by detachably fixing the upper chamber member 21 so that the substantially concave opening faces downward and the opening of the lower chamber member 22 faces upward. Is done.
A preheating ring 23 is attached to the inner peripheral surface on the upper end side of the lower chamber member 22. The inner diameter dimension of the preheating ring 23 is set larger than the outer diameter dimension of a susceptor 31 described later.

On the side surface of the reaction vessel 2, a reaction gas supply pipe and a reaction gas discharge pipe (not shown) for flowing the reaction gas in a substantially horizontal direction on the film formation surface W <b> 1 of the wafer W are provided. Further, a purge gas supply pipe and a purge gas discharge pipe (not shown) are provided on the side surface of the reaction vessel 2 for flowing the purge gas in a direction substantially equal to the reaction gas below the susceptor 31.
Here, as the reaction gas, a material gas mixed with a carrier gas in addition to a source gas for vapor-phase growth of the epitaxial film E can be employed. As the source gas, a gas corresponding to the epitaxial film E to be vapor-phase grown may be employed. For example, a mixed reaction gas obtained by diluting SiHCl _{3 as} a silicon source and boron dopant source B ₂ H ₆ with hydrogen gas can be employed. . As the carrier gas, for example, a gas containing hydrogen (carrier hydrogen) can be adopted.
Furthermore, various types of purge gas can be employed, such as hydrogen gas (slit hydrogen).

The susceptor device 3 holds a wafer W having a diameter of 200 mm or 300 mm and is installed inside the reaction vessel 2. The susceptor device 3 includes a susceptor 31, a peripheral edge support means 32, and a center rod 33 as a temperature control means.
The susceptor 31 is formed in a substantially disk shape in plan view. One surface of the susceptor 31 is a mounting surface 311 on which the wafer W is mounted. A concave portion (not shown) having a circular shape in plan view corresponding to the outer shape of the wafer W is formed at the center of the mounting surface 311, and the center of the susceptor 31 and the center of the wafer W substantially coincide with each other in the concave portion. The wafer W is installed in the state.
The peripheral support means 32 is made of a translucent member such as quartz, protrudes from the central portion of the lower chamber member 22 of the reaction vessel 2 into the reaction chamber 2A, and installs the susceptor 31 in the reaction vessel 2 in a horizontal state. The wafer W is placed on the susceptor 31. The peripheral edge support means 32 is configured to be rotatable about the rotation axis R. The peripheral support means 32 includes a support main body 321 projecting into the reaction chamber 2A from the central portion of the lower chamber member 22, and three peripheral support lots 322 extending obliquely upward from the upper end of the support main body 321. It is equipped with.
The peripheral support lots 322 are provided at intervals of about 120 ° in plan view. The susceptor 31 is installed horizontally in the reaction chamber 2A by supporting the vicinity of the periphery of the non-mounting surface 312 of the susceptor 31 at three points by the tip portions of the three peripheral support lots 322. The
Note that three or more peripheral support lots 322 may be provided, or a substantially conical cylindrical member extending radially from the upper end of the support body 321 may be provided instead of the peripheral support lot 322.

  Moreover, the upper end surface of the support main body part 321 is provided with a rod fitting recess 321A into which the lower end of the center rod 33 is detachably fitted. The center rod 33 is formed in a substantially cylindrical shape by a transparent member such as quartz, and the lower end thereof is fitted into the rod fitting recess 321 </ b> A, whereby the non-mounting surface on the non-mounting surface 312 side of the susceptor 31. It is installed so as to extend in a direction (vertical direction) substantially orthogonal to 312. Further, the surface of the center rod 33 is roughened by a sand blast process, and diffuses the radiation light irradiated from the heating unit 4 for heating the wafer W. Here, the length dimension of the center rod 33 is set such that the temperature control separation distance D between the upper end of the center rod 33 and the non-mounting surface 312 is 4 mm or more and 20 mm or less, and the upper end is not mounted. It is provided in a state in which it is close to the center of the mounting surface 312 without contacting. The diameter of the portion of the center rod 33 that is not fitted in the rod fitting recess 321A is set to 3.0 mm or more and 22.0 mm or less. Here, the diameter of the center rod 33 can be exemplified as 4.7 mm when the diameter of the wafer W is 200 mm, and 20.5 mm when the diameter of the wafer W is 300 mm.

The heating unit 4 includes a plurality of front side light emitting and heating means 41 provided above the reaction vessel 2 and a plurality of back side light emitting and heating means 42 provided below the reaction vessel 2. The back side light emission heating means 42 is arranged in a ring shape substantially concentric with the susceptor 31, and irradiates radiation light from below the reaction vessel 2 to heat the wafer W and the susceptor 31. Although not shown here, the front surface side light emitting and heating means 41 is arranged in a ring shape substantially concentric with the susceptor 31 similarly to the back surface side light emitting and heating means 42, and the wafer W and the susceptor 31 from above the reaction vessel 2. Heat.
For example, a halogen lamp or an infrared lamp can be used as the front side light emitting and heating means 41 and the back side light emitting and heating means 42.
The heating unit 4 includes an in-front reflection unit 43, a back-inside reflection unit 44, an out-of-surface reflection unit 45, and a back-outside reflection unit 46, each formed in a substantially cylindrical shape. The front reflection part 43 and the back reflection part 44 are provided so as to protrude in a direction approaching the susceptor 31 from a substantially ring-shaped internal space constituted by the front side light emission heating means 41 and the back side light emission heating means 42. . The outer reflection part 45 and the outer reflection part 46 are provided so as to surround the above-described protruding portions of the inner reflection part 43 and the inner reflection part 44. The radiant light emitted from the surface-side light emitting and heating means 41 passes between the inner reflection part 43 and the outer reflection part 45 and is reflected by these to irradiate the wafer W. Further, the radiation light emitted from the back side light emitting and heating means 42 passes between the back inner reflection portion 44 and the back outer reflection portion 46 and is reflected by these to irradiate the non-mounting surface 312 of the susceptor 31. Is done.

[Method of manufacturing epitaxial wafer]
Next, a method for manufacturing the epitaxial wafer WE using the manufacturing apparatus 1 described above will be described.
First, the front surface side light emitting and heating means 41 and the back surface side light emitting and heating means 42 are driven to heat the susceptor 31 on which the wafer W is placed to a desired growth temperature.
Then, as shown below, the epitaxial film E is vapor-phase grown on the film formation surface W1 of the wafer W while rotating the peripheral support means 32 about the rotation axis R.
Specifically, immediately before the vapor phase growth, for example, gas phase etching is performed by flowing hydrogen chloride gas, which is a corrosive gas, to the film formation surface W1 of the wafer W, and natural oxidation of the film formation surface W1 is performed. Remove the membrane. Thereafter, a reaction gas is always supplied horizontally on the film formation surface W1 of the wafer W, and a purge gas is introduced below the susceptor 31 at a predetermined timing.
That is, by controlling the flow rate of the reactive gas and the flow rate of the purge gas, a reactive gas flow is formed in which the reactive gas flows through the upper side of the wafer W during the vapor phase growth of the epitaxial film E, and the purge gas flows below the susceptor 31. A flowing purge gas stream is formed. By performing vapor phase growth in this way, an epitaxial film E is formed on the surface of the wafer W, and an epitaxial wafer WE is manufactured.

By the way, the back surface side light emission heating means 42 is arranged in a substantially ring shape. For this reason, when the center rod 33 is not provided, the irradiation amount of the radiant light from the back surface side light emitting and heating means 42 in the susceptor 31 is greater in the center than in the peripheral side, and the temperature of the susceptor 31 is in the center than in the peripheral side. Is higher.
On the other hand, since the manufacturing apparatus 1 is provided with the center rod 33, a part of the radiation light L (see FIG. 1) irradiated toward the center of the susceptor 31 is irregularly reflected by the center rod 33, that is, blocked. And does not reach the center of the susceptor 31. For this reason, compared with the case where the center rod 33 is not provided, the irradiation amount of the radiant light to the center of the susceptor 31 is reduced, and the temperature at the center is lowered. Further, since the center rod 33 is not in surface contact with the susceptor 31, the center rod 33 does not take heat away from the susceptor 31, and a local temperature drop at the center of the susceptor 31 is suppressed.
From the above, the susceptor 31 is heated to a state in which the temperature at the center is appropriately lowered as compared with the configuration in which the center rod 33 is not provided. Therefore, the epitaxial film E having a small thickness variation in the central portion can be vapor-phase grown without greatly reducing the amount of the reaction gas.

[Effects of Embodiment]
In the embodiment as described above, the following operational effects can be obtained.
(1) A substantially cylindrical center rod 33 is contacted with the manufacturing apparatus 1 so as to extend in the vertical direction on the non-mounting surface 312 side of the susceptor 31 and the upper end contacts the center of the susceptor 31 (susceptor center corresponding portion). It is provided in a state of being close to each other.
For this reason, as described above, it is possible to reduce the thickness variation in the central portion without greatly reducing the amount of the reaction gas, and it is possible to prevent abnormal growth from occurring on the back surface of the epitaxial wafer WE.

  (2) Since the temperature control separation distance D is set to 4 mm or more and 20 mm or less, the susceptor 31 and the center rod 33 do not approach each other too much, and the susceptor 31 does not absorb a large amount of heat locally, and radiation light is emitted. The decrease in the light shielding effect of L can be suppressed, and the film thickness variation in the central portion can be reduced.

  (3) Since the surface of the center rod 33 is sandblasted, a sufficient light-shielding effect can be obtained compared to the case where the surface is kept transparent without sandblasting, and the epitaxial film thickness variation is small. Wafer WE can be manufactured.

  (4) Since the center rod 33 is detachably provided on the support main body 321 of the peripheral support means 32, the center rod 33 is etched before the center rod 33 is etched with hydrogen chloride gas and the length and thickness thereof are greatly changed. Can be easily replaced, and a stable quality epitaxial wafer WE can be manufactured.

  (5) Since the diameter of the portion of the center rod 33 not fitted in the rod fitting recess 321A is set to 3.0 mm or more and 22.0 mm or less, the center portion of the epitaxial wafer WE having diameters of 200 mm and 300 mm Variation in film thickness can be reduced.

[Other Embodiments]
Note that the present invention is not limited to the above embodiment, and various improvements and design changes can be made without departing from the scope of the present invention.

That is, as the shape of the center rod 33, if it is substantially rod-shaped, the entire shape or the upper end side thereof may be formed in a polygonal column shape, a cylindrical shape, a rectangular tube shape, a conical shape, or a pyramid shape. The center rod 33 formed of a transparent member such as quartz may not be sandblasted, or the center rod 33 may be formed of an opaque member such as opaque quartz or SiC (silicon carbide). The center rod 33 and the peripheral support means 32 may be integrally formed so that the center rod 33 cannot be detached from the peripheral support means 32.
Further, when the film is formed in a state where the center of the susceptor 31 and the center of the wafer W placed on the susceptor 31 do not coincide with each other, the upper end of the center rod 33 is not the center of the non-mounting surface 312. By providing it close to the position corresponding to the center of the wafer W shifted from the center of the non-mounting surface 312, it is possible to obtain the same effect as the above embodiment.
Further, the temperature control separation distance D and the diameter of the center rod 33 are not limited to the above values, and other values may be appropriately applied.

  Next, the effect of this invention is demonstrated based on a specific Example.

{Relationship between presence / absence of center rod, variation in thickness of central portion and abnormal growth of back surface under film forming conditions in which variation in thickness at central portion is small with three-point support configuration (configuration without center rod)}
A sample of Example 1 and a sample of Comparative Example 1 were produced by processing a wafer having a diameter of 200 mm under the conditions shown in Table 1 below using an apparatus similar to the manufacturing apparatus 1 of the above embodiment.
The conditions other than those shown in Table 1, that is, the conditions of the reaction gas flow rate, the reaction gas concentration, the growth time, the slit hydrogen flow rate, and the total flow rate are the same in Example 1 and Comparative Example 1. Further, SLM (Standard Liter per Minute), which is a unit of flow rate, is a value obtained by converting the flow rate at 0 ° C. and 1 atm into Liter / Min. The total flow rate is the total flow rate of the process gas used in the epitaxial film manufacturing process, and is the sum of the flow rate of carrier hydrogen and the flow rate of the reaction gas. Furthermore, the center rod was formed in a cylindrical shape and the surface was sandblasted.

Then, at a plurality of positions along the radial direction in the samples of Example 1 and Comparative Example 1, the film thickness (epi film thickness) of the epitaxial film was measured and the epi film thickness was indexed. Specifically, as the indexing process, a value obtained by dividing the epi film thickness at each position by the total average epi film thickness of the sample (in FIG. 3, expressed as epi film thickness / ave [au]). Calculated. The result is shown in the graph of FIG.
The carrier hydrogen flow rate (reaction gas flow rate) shown in Table 1 is a film thickness variation (about ± 50 mm from the center (half the diameter of the epitaxial wafer (200 mm)) in the sample of Comparative Example 1 having a three-point support configuration. The variation of the film thickness at the position of the substantially circular portion having a diameter of 1) was set to be small.

As shown in FIG. 3, it was confirmed that at the carrier hydrogen flow rate in which the central part film thickness variation of Comparative Example 1 was small, the central film thickness variation in the sample of Example 1 was large.
Moreover, it has confirmed that the abnormal growth had generate | occur | produced on the back surface of the sample of the comparative example 1 and Example 1. FIG.
From the above, it was confirmed that, in the three-point support configuration, it is difficult to achieve both the prevention of abnormal growth on the back surface and the reduction in the film thickness variation at the center.
In addition, in the configuration where the center rods are close to each other without contact (rod proximity configuration), even if the carrier hydrogen flow rate is set so that the variation in the central film thickness can be reduced in the three-point support, the epi central film thickness is compared with the surrounding area. It was confirmed that the film thickness became extremely small and the film thickness variation in the central part increased. This is thought to be because the epi-center film thickness was reduced because the radiation emitted toward the susceptor center-corresponding portion was shielded by the center rod and the temperature of the susceptor center-corresponding portion decreased.

{Relationship between carrier hydrogen flow rate and center thickness variation in the proximity of rods}
Samples of Examples 2 to 5 were produced by processing a wafer having a diameter of 200 mm under the conditions shown in Table 2 below using the same apparatus as in Example 1. The conditions other than the conditions shown in Table 2 were the same as those of the sample of Example 1 above.
And the epitaxial film thickness in each position was indexed. The result is shown in the graph of FIG.

As shown in FIG. 4, it was confirmed that as the carrier hydrogen flow rate increased, that is, as the reaction gas flow rate increased, the epi central film thickness and the surrounding film thickness increased. Moreover, it was confirmed that the epi-center film thickness can be shifted from a thinner state to a thicker state than the surrounding film thickness by adjusting the carrier hydrogen flow rate in the range of 30 SLM to 60 SLM. Further, although the back surface abnormal growth occurred in the sample of Example 2, it was confirmed that no abnormal growth occurred in Examples 3 to 5.
From the above, by adjusting the carrier hydrogen flow rate to 40 SLM or more, it is possible to adjust the epi film thickness within a radius of 50 mm from the center, to reduce the film thickness variation at the center, and to prevent abnormal growth of the back surface. It was confirmed that both can be achieved.

{Relationship between center rod installation state and central film thickness variation (wafer having a diameter of 200 mm) under film formation conditions in which the central film thickness variation is small in the rod proximity configuration}
Samples of Example 6 and Comparative Examples 2 and 3 were produced by processing a wafer having a diameter of 200 mm under the conditions shown in Table 3 below using the same apparatus as in Example 1. The conditions other than the conditions shown in Table 3 were the same as those of the sample of Example 1 above. And the epitaxial film thickness in each position was indexed. The result is shown in the graph of FIG.
Note that the carrier hydrogen flow rate shown in Table 3 was set so that the film thickness variation in the central portion of the sample of Example 6 having a rod proximity configuration was small, and abnormal growth did not occur on the back surface.

As shown in FIG. 5, in the carrier hydrogen flow rate in which the central part film thickness variation in Example 6 is small, the epitaxial central film thickness in Comparative Example 2 (three-point support configuration) is thicker than the surroundings, so that the central film thickness is increased. It was confirmed that the variation in the central part film thickness was increased when the epi central film thickness in Comparative Example 3 (4-point support configuration) was locally thinner than the surroundings.
In the case of the three-point support structure, since there is no center rod, it is considered that the susceptor center-corresponding portion is irradiated with radiation light, and this portion becomes high temperature, so that the epi-center thickness is increased. In the case of a four-point support configuration, the center rod is in surface contact with the susceptor center corresponding portion, so that the surface contact portion absorbs heat and the radiant light is shielded to lower the temperature so that the epi center film thickness is reduced. It will be thinner.

{Relationship between center rod installation state and central film thickness variation (wafer having a diameter of 300 mm) under film forming conditions in which the central film thickness variation is small in the rod proximity configuration}
Samples of Example 7 and Comparative Example 4 were prepared by processing a wafer having a diameter of 300 mm under the conditions shown in Table 4 below using the same apparatus as in Example 1. The conditions other than the conditions shown in Table 4 were the same as those of the sample of Example 6 above. And the epitaxial film thickness in each position was indexed. The result is shown in the graph of FIG.
The carrier hydrogen flow rate shown in Table 4 was set so that the variation in the film thickness at the center of the sample of Example 7 having a rod proximity configuration was small and abnormal growth did not occur on the back surface.

As shown in FIG. 6, in the carrier hydrogen flow rate in which the central portion film thickness variation in Example 7 is small, the epitaxial central film thickness in Comparative Example 4 (three-point support configuration) is thicker than the surroundings, so that the central film thickness is increased. It was confirmed that the variation became large.
From the above, it was confirmed that the thickness variation of the central portion of the wafer having a diameter of 300 mm can be reduced by setting the diameter of the center rod to 20.5 mm.
Further, from the result of the wafer having a diameter of 200 mm shown in FIG. 5 and the result of the wafer having a diameter of 300 mm shown in FIG. 6, even when the present invention is applied to the wafer having a diameter of 450 mm, the film thickness variation in the central portion can be reduced. I can guess.

{Relationship between temperature control separation distance and center part film thickness variation}
Samples of Examples 8 to 14 were manufactured by processing a wafer having a diameter of 200 mm under the conditions shown in Table 5 below using the same apparatus as in Example 1. The conditions other than the conditions shown in Table 5 were the same as those of the sample of Example 6 above. And the epitaxial film thickness in each position was indexed. The results are shown in the graphs of FIGS.

  As shown in FIGS. 7 and 8, it was confirmed that as the temperature control separation distance D was increased, the epi central film thickness was increased, and the central film thickness variation was reduced.

{Relationship between temperature control separation distance and center dent}
Using the same apparatus as in Example 1, the temperature control separation distance D was set to the value shown on the horizontal axis of FIG. 9, and a wafer having a diameter of 200 mm was processed to produce a sample.
In addition, the conditions other than the temperature control separation distance D applied the same conditions as the sample of the said Examples 8-14. And the epitaxial film thickness in each position was measured, and the center dent based on the following formula | equation (1) was computed. The result is shown in the graph of FIG.

[Equation 1]
Center recess (%) = (M0−M10) / AVE (1)
M10: Epi film thickness at a position +10 mm from the wafer center M0: Epi center film thickness AVE: Average film thickness of the entire wafer

  As shown in FIG. 9, by setting the temperature control separation distance D to 4 mm or more, the central dent becomes −0.15% or more, and it is possible to suppress large heat absorption by the center rod, thereby reducing the local temperature drop. It was confirmed that it could be prevented. In addition, by setting the temperature control separation distance D to 20 mm or less, the central dent becomes 0% or less, the reduction of the light shielding effect by the center rod can be suppressed, and the temperature of the susceptor center corresponding part becomes higher than other parts. It was confirmed that it can be prevented. From the above, it was confirmed that the variation in the film thickness at the central portion was extremely reduced by setting the temperature control separation distance D to 4 mm or more and 20 mm or less.

{Relationship between presence / absence of center rod, in-plane film thickness distribution of epi film thickness, and average value of epi film thickness under film forming conditions in which central part film thickness variation is small in the rod proximity configuration}
Using a manufacturing apparatus different from that of Example 1 above, a wafer having a diameter of 200 mm was processed under the conditions shown in Table 6 below, thereby preparing 11 samples of Example 15 and 8 samples of Comparative Example 5. The conditions other than the conditions shown in Table 6 were the same as those of the sample of Example 6. And the process capability index | exponent Cp of the in-plane film thickness distribution of the epi film thickness in Example 15 and Comparative Example 5 was calculated | required. The result is shown in the graph of FIG. Moreover, the process capability index | exponent Cpk of the average value of the epitaxial film thickness in Example 15 and Comparative Example 5 was calculated | required. The result is shown in the graph of FIG.

As shown in FIG. 10, the process capability index Cp of the in-plane film thickness distribution is larger in Example 15 having the rod proximity configuration than Comparative Example 5 having the three-point support configuration, and the average value is shown in FIG. As shown, it was confirmed that the process capability index Cpk of the average film thickness was almost equal in Comparative Example 5 and Example 15.
From the above, it has been confirmed that by applying the rod proximity configuration, the average value of the epi film thickness can be made substantially equal to that of the three-point support configuration, and the central thickness variation can be made smaller than that of the three-point support configuration.

{Relationship between transparent state of center rod and film forming conditions}
Samples of Examples 16, 17, and 18 were produced by processing a wafer having a diameter of 200 mm under the conditions shown in Table 7 below using the same manufacturing apparatus as in Example 1 and Example 15. The conditions shown in Table 7 and the conditions other than the use of the center rod that was not sandblasted were the same as those of the sample of Example 6 above. And the epitaxial film thickness in Examples 16-18 was measured. The results are shown in the graphs of FIGS.

As shown in Table 7, a transparent center rod etched by a process gas is in a natural devitrification state, that is, when a center rod that is in a state of shielding radiation light is etched with mixed acid, it may become almost transparent. It could be confirmed.
As shown in FIGS. 12 and 13, the film thickness variation in the central portion of the substantially transparent example 17 is larger than that of the natural devitrification example 16. Further, from Table 7, even though the total flow rate of Example 17 is set to 5 (SLM) higher than that of Example 16, the optimum carrier hydrogen flow rate for reducing the central film thickness variation is It turns out that it has fallen above.
Specifically, as shown in FIGS. 12, 14, and 7, in order to make the film thickness variations in the central portion between the example 16 and the example 18 substantially equal, as in the example 18, the example 16 It was confirmed that the total flow rate should be reduced by about 10 (SLM). That is, it can be seen that the light shielding effect in the almost transparent state is lower than that in the natural devitrification state.
For this reason, if the production is continued with the same carrier hydrogen flow rate in the state where the transparency of the center rod is increased by cleaning by maintenance or the like, the epi central film thickness changes and the central film thickness variation becomes large. I was able to confirm.
In other words, even if a transparent center rod is used, by repeating production, the wafer is etched by the gas used for vapor phase etching of the wafer, and the transparency gradually decreases (the light shielding effect becomes stronger). Therefore, in order to suppress the change in the transparency of the center rod as much as possible even after repeated production, it was confirmed that the surface of the center rod must be sufficiently roughened by sandblasting or other methods. .

  The present invention can be used in a susceptor device, an epitaxial wafer manufacturing apparatus, and an epitaxial wafer manufacturing method.

It is sectional drawing which shows the principal part of the manufacturing apparatus of the epitaxial wafer which concerns on one Embodiment of this invention. It is a top view of the manufacturing apparatus of the epitaxial wafer. It is a graph which shows the relationship between the presence or absence of a center rod and the center part film thickness dispersion | variation in the film-forming conditions with which the center part film thickness dispersion | variation becomes small with the three-point support structure which concerns on the Example of this invention. It is a graph which shows the relationship between the carrier hydrogen flow rate in the rod proximity | contact structure in the said Example, and center part film thickness dispersion | variation. It is a graph which shows the relationship (wafer of diameter 200mm) with the installation state of a center rod, and the film thickness dispersion | variation in a center part in the film-forming conditions with which the film thickness dispersion | variation in a center part becomes small by the rod proximity | contact structure in the said Example. It is a graph which shows the relationship (wafer of diameter 300mm) with the installation state of a center rod, and the film thickness dispersion | variation in a center part in the film-forming conditions with which the film thickness dispersion | variation in a center part becomes small by the rod proximity | contact structure in the said Example. It is a graph which shows the relationship between the temperature control separation distance in the said Example, and center part film thickness dispersion | variation. It is a graph which shows the relationship between the temperature control separation distance in the said Example, and center part film thickness dispersion | variation. It is a graph which shows the relationship between the temperature control separation distance in the said Example, and a center dent. It is a graph which shows the relationship between the presence or absence of a center rod, and the process capability index | exponent Cp of the in-plane film thickness distribution of an epi film thickness in the film-forming conditions with which the center part film thickness variation becomes small by the rod proximity | contact structure in the said Example. It is a graph which shows the relationship between the presence or absence of a center rod, and the process capability index | exponent Cpk of the average value of epi film thickness in the film-forming conditions with which the center part film thickness dispersion | variation becomes small with the rod proximity | contact structure in the said Example. It is a graph which shows the film thickness distribution in the natural devitrification state of the center rod in the said Example. It is a graph which shows the film thickness distribution in case the center rod in the said Example is substantially transparent. It is a graph which shows the film thickness distribution in case the center rod in the said Example is a substantially transparent state, and the reaction gas flow volume is made small.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Manufacturing apparatus 2 ... Reaction container 3 ... Susceptor apparatus 31 ... Susceptor 32 ... Periphery support means 33 ... Center rod as temperature control means 42 ... Back surface side light emission heating means 311 ... Mounting surface 312 ... Non-mounting surface E ... Epitaxial Film L ... Radiant light W ... Wafer W1 ... Film formation surface WE ... Epitaxial wafer

Claims (8)

Provided in an epitaxial wafer manufacturing apparatus for manufacturing an epitaxial wafer by vapor-phase growth of an epitaxial film on the film forming surface while irradiating radiation from the back side opposite to the film forming surface of the wafer and heating the wafer A susceptor device for holding the wafer,
A susceptor having a mounting surface on which the wafer is mounted;
Peripheral support means for supporting the vicinity of the periphery of the susceptor;
Temperature control means for controlling the temperature of the portion corresponding to the center of the wafer in the susceptor when the wafer is placed, and
The temperature control means is formed in a substantially rod shape and extends in a direction substantially orthogonal to the non-mounting surface on the non-mounting surface side opposite to the mounting surface, and an end portion on the non-mounting surface side Is provided in a state in which the non-mounting surface is not in contact with a portion corresponding to the center of the wafer and is close to the wafer. The susceptor device according to claim 1,
The distance between the non-mounting surface side end of the temperature control means and the non-mounting surface is set to 4 mm or more and 20 mm or less. The susceptor device according to claim 1 or 2,
The susceptor device, wherein the temperature control means is processed so that a surface reflects the radiation light. The susceptor device according to claim 1 or 2,
The susceptor device, wherein the temperature control means is formed of an opaque member. A susceptor device according to any one of claims 1 to 4,
The susceptor device, wherein the temperature control means is detachably attached to the peripheral edge support means. A susceptor device according to any one of claims 1 to 5,
The diameter of the said temperature control means is set to 3.0 mm or more and 22.0 mm or less. The susceptor apparatus characterized by the above-mentioned. An epitaxial wafer manufacturing apparatus for manufacturing an epitaxial wafer by vapor-phase growing an epitaxial film on a film forming surface of the wafer,
The susceptor device according to any one of claims 1 to 6, which holds the wafer;
This susceptor device is installed inside, and a reaction vessel capable of supplying a reaction gas for vapor-phase growth of an epitaxial film on the film formation surface of the wafer,
Backside light emitting heating means for heating the wafer by radiating radiation from the backside opposite to the film-forming surface of the wafer;
An epitaxial wafer manufacturing apparatus comprising: Holding the wafer in a susceptor device that holds the wafer, supplying a reactive gas to the wafer while heating the wafer by irradiating radiation from the back side opposite to the film-forming surface of the wafer; An epitaxial wafer manufacturing method for producing an epitaxial wafer by vapor-phase-growing an epitaxial film thereon,
The susceptor device corresponds to a susceptor having a placement surface on which the wafer is placed, peripheral support means for supporting the vicinity of the periphery of the susceptor, and the center of the wafer in the susceptor when the wafer is placed. Temperature control means for controlling the temperature of the portion to be
The temperature control means is formed in a substantially rod shape and extends in a direction substantially orthogonal to the non-mounting surface on the non-mounting surface side opposite to the mounting surface, and an end portion on the non-mounting surface side Is provided close to the non-mounting surface without contacting the portion corresponding to the center of the wafer,
The method for producing an epitaxial wafer, wherein the temperature of a portion corresponding to the center of the wafer in the susceptor is controlled by shielding the radiation light by the temperature control means.

Images