JP2014103328A - Contamination detection method of vapor phase growth apparatus and method of manufacturing epitaxial wafer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of detecting a contamination degree of a vapor phase growth apparatus with high sensitivity.SOLUTION: First, a silicon wafer to be a base plate of a semiconductor wafer for contamination evaluation is prepared (S1), and the silicon wafer is carried in to a reactor of a vapor phase growth apparatus of an evaluation target (S2). Then, HCl gas is simultaneously flown in the reactor together with material gas (TCS gas) and carrier gas, and an epitaxial layer is vapor-phase grown on the silicon wafer (S3), and a silicon epitaxial wafer for contamination evaluation is manufactured. At this time, the flow ratio of the HCl gas (HCI gas flow quantity/material gas flow quantity) to the material gas should be 0.01-0.5. After that, the manufactured silicon epitaxial wafer for contamination evaluation is taken out from the reactor (S4), and a lifetime value of the taken-out silicon epitaxial wafer is measured (S5). Finally, a contamination degree of the vapor phase growth apparatus of the evaluation target is evaluated from the measured lifetime value.

Description

  The present invention relates to a method for detecting contamination due to metal impurities in a vapor phase growth apparatus and a method for manufacturing an epitaxial wafer using a vapor phase growth apparatus in which the metal contamination level is controlled by applying the method.

  In recent years, a silicon epitaxial wafer obtained by vapor-phase-growing a silicon film on a silicon wafer has been used as a substrate for an image sensor such as a CCD or CIS. In such an epitaxial wafer for an image sensor, it is important to reduce the level of metal impurities in the wafer. This is because if a metal impurity is present in the wafer, a defect called white scratch (white spot) occurs.

  In general, in order to manufacture an epitaxial wafer, an epitaxial layer is vapor-phase grown at a high temperature. Therefore, when the epitaxial layer is formed, if metal impurities are present in the reactor of the vapor phase growth apparatus, the manufactured epitaxial wafer is contaminated by the metal impurities. Examples of these metal contamination sources include, in addition to silicon crystals used as a raw material, metal impurities attached during the maintenance (cleaning) of the vapor phase growth apparatus, metal impurities contained in the material constituting the reactor, apparatus and piping system For example, stainless steel components that are usually used for the above are considered.

  Conventionally, there is a method in which a wafer is heat-treated in a heat treatment furnace to be evaluated for metal contamination, the degree of metal contamination of the wafer after the heat treatment is measured, and the degree of contamination (cleanliness) of the heat treatment furnace is evaluated based on the measurement result. It is known (see, for example, Patent Document 1). In the method of Patent Document 1, metal impurities in a silicon wafer are measured by a wafer lifetime (hereinafter sometimes referred to as WLT) method. As a typical method of the WLT method, there is a microwave photoconductive decay method minority carrier lifetime method (hereinafter abbreviated as a μPCD method). In this method, for example, a sample (wafer) is irradiated with light, and the lifetime of minority carriers generated is detected by a change in the reflectance of the microwave, thereby evaluating metal impurities in the sample.

  When the metal is taken into the wafer, this WLT value becomes small. Therefore, by measuring and evaluating the WLT value of the wafer subjected to heat treatment or vapor phase growth, the metal contamination in the heat treatment furnace or the vapor phase growth apparatus can be measured. Management can be performed. In other words, by preparing a wafer for contamination control and performing heat treatment in a heat treatment furnace or vapor phase growth apparatus used in the actual process, and measuring the WLT value of the wafer after heat treatment, the heat treatment furnace or vapor phase growth apparatus becomes a metal impurity. Whether it is contaminated or not.

JP 2010-40813 A

  By the way, the vapor phase growth apparatus needs to be regularly maintained. In the maintenance, for example, the vapor phase growth apparatus is opened to the atmosphere, and the reactor and piping are cleaned. Further, when the production of the epitaxial wafer is repeated, silicon deposits are gradually deposited in the reaction furnace, and the deposits cause generation of particles and the like. Therefore, it is necessary to periodically remove the silicon deposits accumulated in the reaction furnace (cleaning in the furnace). As a method for removing the silicon deposit, a method is known in which HCl gas is flowed into the reaction furnace and vapor etching is performed in the reaction furnace with the HCl gas (see, for example, Japanese Patent Application Laid-Open No. 2004-87920).

  However, immediately after such maintenance or vapor etching, the degree of contamination of the vapor phase growth apparatus may be temporarily deteriorated. With conventional methods, epitaxial wafers manufactured immediately after maintenance or vapor etching and after that are manufactured. The difference in the quality (metal contamination degree) of the epitaxial wafers that were produced could not be captured. That is, the conventional method has a problem that the detection sensitivity of the contamination degree of the vapor phase growth apparatus is low. If an epitaxial wafer is manufactured by using a vapor phase growth apparatus in which the contamination level is controlled by applying a conventional method with low detection sensitivity, there is a possibility that a contaminated low-quality epitaxial wafer is obtained.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a method capable of detecting the contamination degree of the vapor phase growth apparatus with high sensitivity and a method capable of producing a high-quality epitaxial wafer with little contamination. .

  The present inventor considered that contamination in the reaction furnace is caused by corrosion of metal constituent materials such as base rings, piping, valves and the like by hydrogen chloride (HCl) which is one of process gases. This HCl is usually used to clean the inside of the reaction furnace by etching before putting a silicon wafer as an epitaxial wafer substrate into the reaction furnace (in-furnace cleaning). When the silicon wafer used as a substrate is placed in the reactor while the HCl used at this time remains in the reactor and an epitaxial layer is formed, the metal component corroded by HCl is taken into the product epitaxial wafer. The amount of contamination becomes high. Therefore, after cleaning in the furnace with HCl, the furnace wafer is sufficiently purged with hydrogen gas so that the HCl component does not remain, and the product wafer is manufactured. However, in order to accelerate the amount of contamination and increase the detection sensitivity of impurities, it has been found that the epitaxial film formation with the HCl component remaining is more susceptible to impurities and the contamination is amplified. It came to.

That is, the contamination detection method of the vapor phase growth apparatus according to the present invention manufactures an epitaxial wafer for contamination evaluation by causing HCl gas to flow simultaneously with the source gas in the chamber of the vapor phase growth apparatus and vapor-growing an epitaxial layer on the wafer. An epitaxial process,
A measurement step for measuring the metal contamination degree of the contamination evaluation epitaxial wafer manufactured in the epitaxial step as the contamination degree of the vapor phase growth apparatus;
It is characterized by including.

  As described above, in the epitaxial process of the present invention, HCl gas is caused to flow simultaneously with the source gas, so that the generation of metal impurities from the contamination source of the vapor phase growth apparatus can be accelerated by the HCl gas. As a result, it is possible to amplify the amount of metal contamination taken into the epitaxial layer as compared with the conventional method in which HCl gas is not flowed. In the measurement process, the contamination evaluation epitaxial wafer with the increased amount of metal contamination is measured, so that the metal contamination level of the wafer, that is, the contamination level of the vapor phase growth apparatus can be measured (detected) with high sensitivity. it can.

  Moreover, it is preferable that the flow rate ratio (HCl gas flow rate / raw material gas flow rate) of HCl gas with respect to the raw material gas which flows in an epitaxial process is 0.01-0.5.

  When the flow rate ratio of HCl gas is 0.5 or more, the etching reaction becomes dominant over the film formation reaction, and the epitaxial layer itself is not deposited. On the other hand, if the flow rate ratio of HCl gas is less than 0.01, the amplification factor of the amount of metal contamination becomes small, and highly sensitive contamination detection cannot be performed. By setting the flow rate ratio of the HCl gas to the source gas in the range of 0.01 to 0.5, an epitaxial layer in which the amount of metal contamination is amplified can be deposited. As a result, metal contamination of the contamination evaluation epitaxial wafer can be amplified, so that the contamination degree of the vapor phase growth apparatus can be detected with high sensitivity.

  In the measurement process of the present invention, the lime time value of the contamination evaluation epitaxial wafer can be measured as the contamination degree of the vapor phase growth apparatus. Thereby, a value (lifetime value) correlated with the contamination degree of the contamination evaluation epitaxial wafer (contamination degree of the vapor phase growth apparatus) can be obtained easily and with high sensitivity.

  Moreover, the raw material gas which flows in an epitaxial process can be made into trichlorosilane gas. By using trichlorosilane (TCS), which is most widely used as a raw material gas for epitaxial wafers, it is highly versatile and can detect the degree of contamination of a vapor phase growth apparatus in a wide range.

  The epitaxial wafer manufacturing method of the present invention is a vapor phase growth apparatus managed by applying the contamination detection method of the vapor phase growth apparatus of the present invention and managing the metal contamination degree measured in the measurement step to be a certain level or less. And producing an epitaxial wafer. As a result, a high-quality epitaxial wafer with little contamination can be manufactured with a high yield.

1 is a side sectional view of a vapor phase growth apparatus 10. FIG. It is the flowchart which showed an example of the outline of the contamination evaluation method of the vapor phase growth apparatus which concerns on this invention. It is the figure which showed the transition over 10 days of the wafer lifetime value in an Example. It is the flowchart which showed an example of the outline of the contamination evaluation method of the conventional vapor phase growth apparatus. It is the figure which showed transition for 10 days of the wafer lifetime value in a comparative example.

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a side cross-sectional view of a single-wafer type vapor phase growth apparatus 10 as a preferred example of a vapor phase growth apparatus to be evaluated for contamination. The vapor phase growth apparatus 10 is an apparatus for growing a silicon single crystal film on the surface of a silicon wafer W (an apparatus for producing a silicon epitaxial wafer). In the vapor phase growth apparatus 10, for example, an epitaxial wafer used for an image sensor substrate such as a CCD or CIS is manufactured.

  The vapor phase growth apparatus 10 includes a chamber base 11 made of SUS and transparent quartz members 13 and 14 forming a reaction furnace 12 (chamber) sandwiched between the chamber base 11 and the chamber base 11 provided inside the reaction furnace 12. Opaque quartz members 15 and 16 that cover from the inside, and a susceptor 17 that horizontally supports the silicon wafer W are provided.

  In the reaction furnace 12, a vapor phase growth gas G containing a source gas (for example, trichlorosilane) and a carrier gas (for example, hydrogen) is introduced into the reaction furnace 12 into a region above the susceptor 17, and the silicon on the susceptor 17. Gas introduction pipes 20 and 21 for supplying the main surface of the wafer W are provided. The reaction furnace 12 is provided with gas discharge pipes 22 and 23 on the side opposite to the side where the gas introduction pipes 20 and 21 are provided.

  Further, heaters 24 and 25 for heating the silicon wafer W to an epitaxial growth temperature (for example, 900 to 1200 ° C.) at the time of epitaxial growth are provided above and below the reaction furnace 12. A plurality of heaters 24 and 25 are provided in the horizontal direction. As the heaters 24 and 25, for example, halogen lamps are employed.

  As described above, the inside of the reaction furnace 12 needs to be vapor-etched (cleaning in the furnace) periodically by maintenance of the vapor phase growth apparatus 10 or HCl gas. In maintenance, since the vapor phase growth apparatus 10 is opened to the atmosphere, metal impurities may be brought into the vapor phase growth apparatus 10 from the outside, or portions exposed to the atmosphere may be corroded to generate metal impurities. In the vapor etching, a reaction product of metal impurities may be generated due to the reaction between the HCl gas and the contamination source, or metal impurities may be generated due to corrosion by HCl remaining in the reaction furnace 12. Therefore, immediately after maintenance or vapor etching, the contamination level of the vapor phase growth apparatus 10 may be temporarily deteriorated. Since devices such as an image sensor are very strongly affected by metal impurities in the epitaxial layer, it is necessary to detect contamination of the vapor phase growth apparatus 10 with high sensitivity. For this reason, the contamination detection method of the present invention is implemented. The

  Next, details of a method for evaluating the degree of contamination of the vapor deposition apparatus 10 including the contamination detection method of the vapor deposition apparatus of the present invention will be described. FIG. 2 is a flowchart showing an example of the outline of the method. The contamination evaluation method shown in FIG. 2 may be performed at any time. For example, it is performed immediately after maintenance or vapor etching (in-furnace cleaning) in which the contamination level deteriorates. First, a silicon wafer serving as a substrate for a semiconductor wafer for contamination evaluation is prepared (S1). The diameter, plane orientation, conductivity type, resistivity, etc. of the silicon wafer prepared here are not particularly limited, but for example, the diameter may be the same as the silicon wafer processed by the vapor phase growth apparatus 10 to be evaluated. For example, it can be 6 to 12 inches (150 to 300 mm). Further, the processing conditions of the surface of the silicon wafer may be standard conditions, but it is preferable to avoid a process that reduces the lifetime, such as a sandblast process or a formation of a polycrystalline silicon film.

  Next, the silicon wafer prepared in S1 is carried into the reaction furnace 12 and placed on the susceptor 17 (S2). Then, unlike the conventional method (S3 ′ in FIG. 4 described later) in which a source gas such as TCS and hydrogen as a carrier gas are flowed to grow an epitaxial layer, HCl gas is simultaneously added to the reactor in addition to the source gas and the carrier gas. The epitaxial layer is vapor-phase grown on the silicon wafer (S3), and a silicon epitaxial wafer for contamination evaluation is produced. The thickness, conductivity type, resistivity and the like of the epitaxial layer are not particularly limited, but for example, a non-doped epitaxial layer can be grown to a thickness of 1 to 10 μm. Further, the type of the source gas is not particularly limited, but TCS that is most widely used as the source gas can be used. The flow rate ratio between the source gas and the HCl gas (ratio of the flow rate of the HCl gas to the flow rate of the source gas) is preferably 0.01 to 0.5 as described above.

  Thus, in the step S3, HCl gas is supplied simultaneously with the raw material gas, so that generation of metal impurities from the contamination source in the vapor phase growth apparatus 10 can be accelerated by the HCl gas. As a result, metal impurities (amount of metal contamination) taken into the epitaxial layer can be amplified. The process of S3 corresponds to the “epitaxial process” of the present invention.

  Then, the produced silicon epitaxial wafer for contamination evaluation is carried out from the reactor 12 (S4). Thereafter, the lifetime value of the silicon epitaxial wafer is measured as the metal contamination degree of the silicon epitaxial wafer for contamination evaluation that has been carried out (S5). The method for measuring the wafer lifetime value can be a known method, and is not particularly limited, but is preferably performed by the μPCD method, which allows easy measurement. The lifetime value measured in S5 is also the degree of contamination of the vapor phase growth apparatus 10. The process of S5 corresponds to the “measurement process” of the present invention.

  Next, the contamination degree (cleanness) of the vapor phase growth apparatus 10 to be evaluated is evaluated from the lifetime value measured in S5 (S6). If impurities, particularly metal impurities, are taken into the silicon epitaxial layer of the silicon epitaxial wafer for contamination evaluation, the lifetime value becomes small. Therefore, when the lifetime value of the silicon epitaxial wafer for contamination evaluation is small (for example, when the lifetime value is smaller than a predetermined threshold, or the lifetime value of the silicon wafer before vapor phase growth) In the case where the amount of decrease from (2) is greater than or equal to a predetermined value), it can be evaluated that the contamination degree of the vapor phase growth apparatus 10 is high (cleanness is low). On the other hand, if the lifetime value decrease is small, it can be evaluated that the contamination of the silicon epitaxial wafer for contamination evaluation derived from the vapor phase growth apparatus 10 is low, and the contamination level of the vapor phase growth apparatus 10 is low (cleanness is high). ).

  The above is the evaluation method of the vapor phase growth apparatus of this embodiment. As described above, according to the evaluation method of the present embodiment, HCl gas is also flowed in addition to the source gas during the growth of the epitaxial layer, so that contamination due to corrosion of the reactor can be emphasized and accelerated. Contamination is amplified, and the degree of contamination (cleanness) can be evaluated with high sensitivity. For example, by using the vapor phase growth apparatus 10 that is managed so that the degree of contamination (lifetime value) measured in the step S5 is below a certain level, a high-quality epitaxial wafer with little contamination is manufactured at a high yield. be able to.

  As a procedure for manufacturing an epitaxial wafer for a product, a silicon wafer W is introduced into a reaction furnace 12 adjusted to an input temperature (for example, 650 ° C.) and placed on a susceptor 17 so that the surface thereof faces upward. To do. Here, hydrogen gas is introduced into the reactor 12 through the gas introduction pipes 20 and 21 and the purge gas introduction pipe from the stage before the silicon wafer W is introduced.

  Next, the silicon wafer W on the susceptor 17 is heated to a hydrogen heat treatment temperature (for example, 1050 to 1200 ° C.) by the heaters 24 and 25. Next, vapor phase etching for removing the natural oxide film formed on the surface of the silicon wafer W is performed. Note that this vapor phase etching is performed until immediately before the vapor phase growth which is the next step.

  Next, the temperature of the silicon wafer W is lowered to a desired growth temperature (for example, 1050 to 1180 ° C.), and a raw material gas (for example, trichlorosilane) is supplied onto the surface of the silicon wafer W through the gas introduction tubes 20 and 21. A purge gas (for example, hydrogen) is supplied almost horizontally through the silicon wafer W to vapor-grow a silicon single crystal film on the surface of the silicon wafer W to obtain a silicon epitaxial wafer. Finally, the silicon epitaxial wafer is taken out and lowered to a temperature (for example, 650 ° C.) and carried out of the reaction furnace 12.

  EXAMPLES Hereinafter, although an Example and a comparative example are given and this invention is demonstrated further more concretely, these do not limit this invention.

(Example)
First, as a silicon wafer, many P-type silicon wafers having a diameter of 200 mm, a resistivity of 10 Ωcm, and a thickness of 725 μm were prepared. Next, two vapor phase growth apparatuses to be evaluated were prepared, each was opened to the atmosphere, and so-called maintenance work was performed. At that time, one unit performed maintenance work immediately after it was released to the atmosphere (hereinafter referred to as normal maintenance), and the other unit was left open for one day with the atmosphere open, and then maintenance work was performed (hereinafter referred to as maintenance after one day release). Called).

  In general, when maintenance work is performed, the reactor inside the vapor phase growth apparatus is slightly contaminated, and it takes several days from the maintenance until the contamination source is almost removed and the influence of the contamination is almost eliminated (contamination is withered). . In addition, if the open time in the atmosphere is long, the corrosion proceeds accordingly, so the amount of contamination in the vapor phase growth apparatus is considered to increase.

  Thus, after preparing the vapor phase growth apparatus which performed two types of maintenance work, in addition to source gas TCS10L / min and carrier gas hydrogen 50L / min at the time of epitaxial layer film formation using these apparatuses, HCl Gas was flowed at 2 L / min, and an epitaxial layer was grown on the above silicon wafer to produce a silicon epitaxial wafer for contamination evaluation (S1 to S4 in FIG. 2). At this time, the epitaxial layer was formed into a P-type having a resistivity of 10 Ωcm and a film thickness of 10 μm. Further, a silicon epitaxial wafer for contamination evaluation was produced once a day by the same method. While a silicon epitaxial wafer for contamination assessment is not being produced, the vapor phase growth apparatus is heated in the same sequence as the growth of the silicon epitaxial layer of a normal product, and the process of removing the contamination source is continued. It was.

  Contamination evaluation silicon epitaxial wafers prepared in this way (each of the silicon epitaxial wafers produced once a day) are subjected to surface treatment by chemical passivation and using a wafer lifetime measuring device by μPCD method. The wafer lifetime value was measured (S5 in FIG. 2).

  FIG. 3 is a diagram showing the measurement results, and specifically shows the transition of the wafer lifetime value in the example over 10 days. In the case of a normally grown vapor phase growth apparatus, the wafer lifetime value is about 700 μsec for the contamination-evaluated silicon epitaxial wafer produced immediately after the maintenance, and the wafer lifetime value becomes higher with the passage of days thereafter. It increased to about 1800 μsec. Thereafter, it gradually increased until the 10th day and reached about 1900 μsec.

  On the other hand, in the case of a vapor phase growth apparatus maintained after opening for one day, the wafer lifetime value of the silicon epitaxial wafer for contamination evaluation prepared immediately after the maintenance is about 200 μsec, and the wafer lifetime is increased with the passage of days until the 8th day. The value rose without peaking and increased to about 1900 μsec on the 10th day.

  Thus, in the present invention, the difference in the degree of contamination between normal maintenance and maintenance after one-day opening, specifically, the vapor growth apparatus for maintenance after one-day opening is more maintenance than the vapor growth apparatus for normal maintenance. I was able to clearly see that later recovery of contamination was slow.

(Comparative example)
Next, as a comparative example, an example will be described in which a source gas TCS and a carrier gas hydrogen are flown into a reaction furnace to form an epitaxial layer and a silicon epitaxial wafer for contamination evaluation is produced as in the prior art. FIG. 4 is a flowchart showing an example of an outline of a conventional contamination evaluation method for a vapor phase growth apparatus (comparative example). In FIG. 4, the same steps as those in FIG. In the method of FIG. 4, the step S3 ′ (epitaxial step) is different from the step S3 of FIG. 2, and the other steps are the same as those of FIG.

  First, as a silicon wafer, many P-type silicon wafers having a diameter of 200 mm, a resistivity of 10 Ωcm, and a thickness of 725 μm were prepared. When two vapor phase growth apparatuses that have been subjected to the same two types of maintenance work as in the example were prepared, and the elapsed time after the maintenance was the same as when the silicon epitaxial wafer for contamination evaluation of the example was produced, a comparative example A silicon epitaxial wafer for contamination evaluation was prepared. In this silicon epitaxial wafer for contamination evaluation, a source gas TCS of 10 L / min and a carrier gas of hydrogen of 50 L / min are flowed into the reactor, and a 10 μm P-type silicon epitaxial layer having a resistivity of 10 Ωcm is deposited on the silicon wafer. (S1 to S4 in FIG. 4).

  The silicon epitaxial wafer for contamination evaluation thus produced was subjected to surface treatment by chemical passivation, and the wafer lifetime value was measured using a wafer lifetime measuring apparatus by the μPCD method (S5 in FIG. 4).

  FIG. 5 is a diagram showing the measurement results, and shows the transition of the wafer lifetime value in the comparative example over 10 days. In the case of the vapor phase growth apparatus that is normally maintained, the wafer lifetime value of the silicon epitaxial wafer for contamination evaluation produced immediately after the maintenance is about 800 μsec and increased to about 1800 μsec on the second day. Although it became about 2200 μsec by the 10th day, the wafer lifetime value after the 2nd day peaked out and remained almost the same.

  On the other hand, in the case of a vapor phase growth apparatus maintained after opening for a day, a silicon epitaxial wafer for contamination evaluation prepared immediately after maintenance has a wafer lifetime value of about 700 μsec, which is the same as in the case of a normally maintained vapor phase growth apparatus. On the second day, it increased to about 1800 μsec. Although it became about 2200 μsec by the 10th day, the wafer lifetime value after the 2nd day peaked out and remained almost the same.

  In the comparative example, when the normal maintenance and the maintenance after the opening of the day were performed, the wafer lifetime value was almost the same value, and no significant increase was observed after the second day. This indicates that the comparative example has not been able to detect the contamination degree of the vapor phase growth apparatus that has been normally maintained and maintained after opening for one day with high sensitivity. On the other hand, the example showed a low value compared with the normal maintenance particularly when the maintenance was performed after opening for one day, and the wafer lifetime value continued to rise greatly without reaching the peak after the second day. From this, the Example clearly shows that the degree of contamination of the vapor phase growth apparatus after maintenance can be detected with high sensitivity.

  The present invention is not limited to the above embodiment. The above-described embodiment is an exemplification, and the present invention has substantially the same configuration as the technical idea described in the claims of the present invention, and any device that exhibits the same function and effect is the present invention. It is included in the technical scope of the invention. For example, the vapor phase growth apparatus to be evaluated for the degree of contamination is not limited to a single wafer type, and the present invention can be applied to contamination evaluation of various vapor phase growths such as a vertical type (pancake type) and a barrel side (cylinder type). Further, in the process of S5 in FIG. 2, silicon other than the wafer lifetime method, specifically, for example, silicon for contamination evaluation by ICP-MS (ICP mass spectrometry) or total reflection X-ray fluorescence analysis (TXRF). You may measure the metal contamination degree (concentration of a metal impurity) of an epitaxial wafer. Further, the present invention may be applied to contamination evaluation of a vapor phase growth apparatus for manufacturing a semiconductor epitaxial wafer other than a silicon epitaxial wafer (for example, a compound semiconductor wafer such as GaP).

10 Vapor growth equipment 12 Reactor

Claims (5)

A method for detecting contamination of a vapor phase growth apparatus,
An epitaxial process for producing a contamination evaluation epitaxial wafer by vapor-phase-growing an epitaxial layer on a wafer by simultaneously flowing HCl gas together with a source gas in a reactor of a vapor phase growth apparatus;
A measurement step for measuring the metal contamination degree of the contamination evaluation epitaxial wafer manufactured in the epitaxial step as the contamination degree of the vapor phase growth apparatus;
A contamination detection method for a vapor phase growth apparatus comprising:   The contamination detection method for a vapor phase growth apparatus according to claim 1, wherein a flow rate ratio of the HCl gas to the source gas (HCl gas flow rate / source gas flow rate) is 0.01 to 0.5.   3. The contamination detection method for a vapor phase growth apparatus according to claim 1, wherein in the measurement step, a lime time value of the contamination evaluation epitaxial wafer is measured as a contamination level of the vapor phase growth apparatus.   The contamination detection method for a vapor phase growth apparatus according to any one of claims 1 to 3, wherein the source gas is trichlorosilane gas. 5. A vapor phase growth apparatus, to which the contamination detection method for a vapor phase growth apparatus according to any one of claims 1 to 4 is applied, and the metal contamination degree measured in the measurement step is controlled to be a certain level or less. An epitaxial wafer manufacturing method comprising manufacturing an epitaxial wafer using

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