JP6569640B2 - Box management method and epitaxial wafer manufacturing method - Google Patents

Description

  The present invention relates to a box management method and an epitaxial wafer manufacturing method.

For example, there is a semiconductor element formed by patterning a part of an N-type semiconductor substrate and growing an epitaxial layer on the substrate so as to have the same resistivity as the bulk part of the substrate. Some epitaxial wafers that are the basis of such semiconductor elements have high resistivity in which the resistivity of the substrate and the epitaxial layer is, for example, 5 × 10 ¹⁴ atoms / cm ³ or less in terms of dopant concentration. At the outer periphery of the epitaxial wafer, the dopant concentration distribution from the wafer surface to the wafer depth direction (hereinafter referred to as “dopant concentration profile”) is as shown in the graph of FIG. There is. In FIG. 5, the dopant concentration profile is locally reduced near the interface between the substrate and the epitaxial layer (raised in a hump shape downward). This phenomenon includes a step of cleaning the substrate before growing the epitaxial layer on the substrate, and a step of growing the epitaxial layer on the substrate at the transport destination where the substrate cleaned in this step is stored and transported in a box. It occurs when boron, which is a P-type dopant, adheres to the substrate (N-type). That is, when the substrate is contaminated by a dopant having a conductivity type different from that of the substrate, the carrier of the substrate is canceled, the dopant concentration is lowered at and near the contaminated portion of the substrate, and the dopant concentration profile is disturbed. In an epitaxial wafer, the dopant concentration at the interface between the substrate and the epitaxial layer has a great influence on the characteristics of the semiconductor element, so that it is required to sufficiently control the dopant concentration profile in the vicinity of this interface.

  In this way, boron that disturbs the dopant concentration profile of the epitaxial wafer is generally brought in from an environment in which a semiconductor manufacturing line such as a semiconductor manufacturing apparatus is arranged. For example, Patent Document 1 discloses that boron is contained in glass fibers serving as a filter medium of a HEPA filter, and thus the glass fibers corrode and thereby boron contaminates the environment in the clean room. Therefore, it is considered that the boron concentration generated in the clean room for some reason contaminates the substrate, thereby disturbing the dopant concentration profile of the epitaxial wafer manufactured based on the substrate. In particular, the higher the resistivity of the N-type substrate and the epitaxial layer of the epitaxial wafer, in other words, the lower the dopant concentration, the more susceptible to the contamination by boron due to the presence of very slight boron in the environment. Therefore, even when a boron-less filter is installed in a clean room, contamination with boron may be a problem.

  As one countermeasure against boron that exists in the environment in such a small amount, for example, Patent Document 2 discloses a method in which the surface of the wafer is terminated with hydrogen by hydrofluoric acid treatment. However, if the surface of the wafer is terminated with hydrogen, the number of particles increases extremely, causing a stacking fault during epitaxial growth.

  Patent Documents 3 and 4 disclose that contamination by dopants is concentrated when a pod (box) for carrying a wafer is used.

JP 05-253447 A JP 2008-112892 A JP 2013-070097 A Special table 2010-536185 gazette

  Patent Documents 3 and 4 disclose that a box carrying a wafer is cleaned in order to suppress contamination due to dopants, but there is no disclosure about managing the number of times the box is used in order to suppress contamination.

  An object of the present invention is to provide a box management method and an epitaxial wafer manufacturing method capable of suppressing contamination by impurities.

Means for Solving the Problems and Effects of the Invention

The box management method of the present invention includes:
A first step of acquiring the concentration of a specific impurity in each of the plurality of clean rooms in a clean room in which the substrate is stored and transported in a box;
Acquire the degree of contamination due to specific impurities in the box corresponding to the number of times the box has been transported by storing the board and the number of times the box has been used in each of the multiple clean rooms. A second step of setting an upper limit number that is the upper limit of the number of times the box is used;
Obtaining a correlation between the concentration of the specific impurity and the upper limit number of times based on a plurality of pairs acquired from the respective clean rooms with the concentration of the specific impurity acquired in the first step and the upper limit number of pairs set in the second step; ,
A step of setting the upper limit number of times in a clean room in which the upper limit number is not set from the concentration of the specific impurity in the clean room in which the upper limit number is not set and the correlation;
It is characterized by providing.

The box management method of the present invention acquires the correlation between the upper limit number of times of use of the box set based on the degree of contamination by specific impurities in the box and the concentration of specific impurities in the clean room. Therefore, if the concentration of the specific impurity in the clean room can be acquired, the box can be managed so as to prevent the box from being contaminated by the specific impurity. That is, it is possible to set the upper limit of the number of times of use of the box used in the clean room where the upper limit of the number of times of use of the box is not set.

  In an embodiment of the present invention, the substrate is a silicon single crystal substrate and the specific impurity is boron.

  According to this, it is possible to suppress the box and the silicon single crystal substrate from being contaminated by boron.

  In an embodiment of the invention, the substrate is a high resistivity silicon single crystal substrate doped with an N-type dopant.

Specifically, the substrate is a silicon single crystal substrate doped with phosphorus, arsenic, or antimony as an N-type dopant and having a dopant concentration of 5 × 10 ¹⁴ atoms / cm ³ or less.

  According to this, it is possible to effectively prevent such a silicon single crystal substrate that is easily affected by contamination by boron from being contaminated by boron.

In addition, the manufacturing method of the epitaxial wafer of the present invention,
A first step of acquiring the concentration of a specific impurity in each of the plurality of clean rooms in a clean room in which the substrate is stored and transported in a box;
Acquire the degree of contamination due to specific impurities in the box corresponding to the number of times the box has been transported by storing the board and the number of times the box has been used in each of the multiple clean rooms. A second step of setting an upper limit number that is the upper limit of the number of times the box is used;
Obtaining a correlation between the concentration of the specific impurity and the upper limit number of times based on a plurality of pairs acquired from the respective clean rooms with the concentration of the specific impurity acquired in the first step and the upper limit number of pairs set in the second step; ,
A third step of setting the upper limit number of times in the clean room in which the upper limit number is not set based on the concentration of the specific impurity in the clean room in which the upper limit number is not set and the correlation;
Growing an epitaxial layer on the substrate transported by the box within the upper limit number set by the third step in the clean room where the upper limit number is set by the third step;
It is characterized by providing.

  In the epitaxial wafer manufacturing method of the present invention, an epitaxial layer is grown on a substrate transported by a box in which the upper limit number is set. Therefore, it is possible to manufacture an epitaxial wafer in which impurity contamination is suppressed.

  In an embodiment of the present invention, the substrate is a silicon single crystal substrate and the specific impurity is boron.

  According to this, an epitaxial wafer in which contamination by boron is suppressed can be manufactured.

In an embodiment of the invention, the substrate is a high resistivity silicon single crystal substrate doped with an N-type dopant. Specifically, the substrate is a silicon single crystal substrate doped with phosphorus, arsenic, or antimony as an N-type dopant and having a dopant concentration of 5 × 10 ¹⁴ atoms / cm ³ or less.

In the embodiment of the present invention, the growing step grows a high resistivity epitaxial layer doped with an N-type dopant. Specifically, as the N-type dopant, an epitaxial layer doped with phosphorus, arsenic or antimony and having a dopant concentration of 5 × 10 ¹⁴ atoms / cm ³ or less is grown.

In the above two embodiments, since the dopant concentration of the substrate or the epitaxial layer is 5 × 10 ¹⁴ atoms / cm ³ or less, the epitaxial wafer is easily affected by contamination by boron. However, even in such a case, it is possible to manufacture an epitaxial wafer capable of effectively suppressing boron contamination.

The graph which shows the relationship between the frequency | count of use of a box, and the height of the peak of the dopant density | concentration profile of the outer peripheral part of an epitaxial wafer (peak height shown by dopant density | concentration (atomics / cm < ³ >)). The graph which shows the degree of contamination corresponding to the boron density | concentration (amount of boron (atоms / cm < ² >)) in each clean room, and the frequency | count of use of the box used in each clean room. The graph created in the Example which shows the degree of contamination corresponding to the boron density | concentration (Amount of boron (atоms / cm < ² >)) in each clean room, and the usage frequency of the box used in each clean room. The graph of Example 1 and 2 which shows the height of the peak of the dopant density | concentration profile in the outer peripheral part of an epitaxial wafer (peak height shown by dopant density | concentration (atomics / cm < ³ >)), and a comparative example. The graph which shows the relationship between the depth (micrometer) from the surface in an epitaxial wafer, and the dopant concentration (atomics / cm < ³ >) of the epitaxial wafer corresponding to the depth.

  Hereinafter, as an example of the method for producing an epitaxial wafer of the present invention, a method for producing a silicon epitaxial wafer by growing a silicon epitaxial layer on a silicon single crystal substrate will be described. In the following description, a cleaning device for cleaning a substrate cut out from a silicon single crystal ingot and subjected to a predetermined process, a box B used for transporting the substrate from the cleaning device, and transported using the box B A method of manufacturing an epitaxial wafer using a vapor phase growth apparatus that performs vapor phase growth on a substrate will be described.

In order to manufacture a silicon epitaxial wafer using a vapor phase growth apparatus, first, a silicon single crystal substrate which is a growth substrate on which an epitaxial layer is grown is manufactured. For example, polycrystalline silicon and quartz silicon crucible and N-type dopant (phosphorus, arsenic, or antimony) to adjust the resistivity are immersed in a liquid surface of a molten liquid and pulled up to obtain a silicon single-piece. A crystal ingot is produced. At the time of producing the silicon single crystal ingot, phosphorus, arsenic, or antimony is added as a dopant at 5 × 10 ¹⁴ atoms / cm ³ or less (for example, phosphorus is added at 5 × 10 ¹⁴ atoms / cm ³ ). Then, after the silicon single crystal ingot thus produced is cut out to a predetermined thickness, the cut wafer is subjected to rough polishing, etching, polishing, etc. to produce a substrate W in a state where the surface is mirror-finished. The substrate W is adjusted to have an N conductivity type and a resistivity of, for example, 10 Ω · cm or more by a dopant added when a silicon single crystal ingot is manufactured.

  The produced substrate W is transported to a known cleaning apparatus, and dirt attached to the substrate W is cleaned in the steps so far. A known cleaning apparatus includes a load port for mounting a box B for storing and transporting a plurality of substrates W, and a plurality of cleaned substrates W are stored in the box B mounted on the load port. The

  The box B placed on the load port of the cleaning device includes a container-like main body having an opening and a lid for closing the opening. A sealed space is formed inside the box B with the lid portion closing the opening of the main body portion. When the box B arranged in the load port is opened so that the inside of the box B is shielded from the outside air, and a predetermined number of substrates W washed in the main body from the opened opening is stored, The opening of the main body is sealed by the lid. In a state where the substrate W is stored in the box B thus sealed, the substrate W together with the box B is automatically transferred from the cleaning apparatus to a known vapor phase growth apparatus.

  A known vapor phase growth apparatus into which a box B containing a substrate W is carried includes, for example, a load port for placing the box B and a transfer robot for taking out the substrate W from the box B placed on the load port. When the box B is placed on the load port of the vapor phase growth apparatus, the lid is opened so that the inside of the box B is shielded from the outside air, and the substrate is taken out from the opened opening by the transfer robot. The substrate W is epitaxially grown. Specifically, the growth conditions are set so that an epitaxial layer having a dopant concentration equivalent to the dopant concentration of the substrate W is grown. For example, a 4 μm silicon epitaxial layer is grown on the substrate W, and a silicon epitaxial wafer is grown. To manufacture.

  The substrate W of the epitaxial wafer manufactured as described above has an N conductivity type, and the dopant concentration of the substrate W is low. Therefore, only a small amount of P-type boron exists in the environment for manufacturing such an epitaxial wafer, and the manufactured epitaxial wafer is affected by the contamination by boron. Such boron contamination occurs, for example, when P-type boron adheres to the N-type substrate W while the substrate W cleaned by the cleaning device is stored in the box B and transferred to the vapor phase growth apparatus. To do. When an epitaxial wafer is manufactured by growing an epitaxial layer on such a substrate W, adhering boron diffuses in the wafer by heating, and in the depth direction of the manufactured wafer, the location where the substrate W is contaminated and its vicinity Thus, carriers are canceled out and the substantial dopant concentration is lowered. As a result, the dopant concentration profile of the epitaxial wafer is disturbed.

The present inventor has conducted research from various angles in order to identify the source of boron contamination that causes the dopant concentration profile to be disturbed in this way. An example of the investigation result is shown in FIG. FIG. 1 shows the number of times the box B is transferred from the cleaning apparatus to the vapor phase growth apparatus and the box B is transferred (the number of times the box B is used), and an epitaxial layer is grown on the substrate W transferred in the box B. In addition, the peak height at which the dopant concentration profile on the outer peripheral portion of the epitaxial wafer locally decreases is shown. The height of this peak is obtained by calculating the height of the peak portion from the dopant concentration (atomics / cm ³ ) obtained by measuring the dopant concentration profile at the outer peripheral portion of the epitaxial wafer by the spreading resistance measurement method. Is indicated by the dopant concentration (atomics / cm ³ ). For example, the dopant concentration profile in FIG. 5 shows a peak in which the dopant concentration locally decreases at and near the interface between the substrate W and the epitaxial layer. In FIG. 1, the height of such a peak was calculated. . In FIG. 1, it can be seen that the peak height of the dopant concentration profile increases as the number of uses of box B increases, and that the peak height tends to saturate when the number of uses is 20 or more. Therefore, when transporting the substrate W from the cleaning apparatus to the vapor phase growth apparatus, it is preferable to use the box B that is used less frequently.

  Here, the height of the peak of the dopant concentration profile shown in FIG. 1 is a result obtained from an epitaxial wafer manufactured based on the substrate W transported using the box B in a single clean room. The inventor investigated the number of times the box B was used until the peak height of the dopant concentration profile was saturated in the same manner as in FIG. 1 in a clean room different from that in FIG. As a result, the number of times that the box B is used until the peak height is saturated is different from that in FIG. 1, and therefore the result of the investigation in FIG. The present inventors faced this fact. In the face of this fact, the present inventor conducted intensive research and trial and error, and the boron concentration in the clean room and the peak height of the dopant concentration profile of the epitaxial wafer produced in the clean room were saturated until the box B It was found that there is a strong correlation between the number of uses. In other words, the present inventors have a correlation between the boron concentration in the clean room and the upper limit number of times of use of the box B used in the clean room (hereinafter referred to as “the upper limit number of box B”). Found.

  Therefore, in the embodiment of the present invention, the correlation between the boron concentration in the environment of the clean room using the box B and the upper limit number of the box B used in the clean room is acquired. Then, using this correlation, the upper limit number of boxes B is set for a clean room in which the upper limit of the number of uses of box B is not set. Below, the method to acquire said correlation from the some clean room located in a different place is demonstrated.

  First, the boron concentration in the clean room in which the substrate W is stored and transported in the box B is acquired from each of the plurality of clean rooms (first step). For example, the boron concentration in each clean room is measured using a wafer exposure method. Specifically, the substrate W is exposed in each clean room for a predetermined time, and the contamination of the surface of the substrate W after the exposure is recovered with a hydrofluoric acid solution, and the contamination (contamination by boron) of the substrate W is ICP-MS. Measure by the method. Then, the amount of boron obtained by the measurement is acquired as the boron concentration in the clean room.

  When the first step is finished, the degree of boron contamination in the box B corresponding to the number of times the box B is transferred from the cleaning apparatus to the vapor deposition apparatus (the number of times the box B is used) is stored in a plurality of clean rooms. Get from each of the. Then, the upper limit number of boxes B is set for each clean room based on the obtained degree of boron contamination (second step). Specifically, a box B is used that is used in each clean room, and is used 10 times, 20 times, 30 times, and 40 times. The substrate W is transferred from the cleaning apparatus to the vapor phase growth apparatus. And the dopant concentration profile of the outer peripheral part of the epitaxial wafer produced by growing the epitaxial layer on each substrate W transported to the vapor phase growth apparatus is spread and measured by a resistance measurement method. Thereafter, the height of the peak at which the dopant concentration is locally reduced at and near the interface between the substrate W and the epitaxial layer is obtained as the degree of contamination in the box B from each measured dopant concentration profile. In this way, the degree of contamination in the box B corresponding to the number of times the box B is used is acquired from each clean room. And the upper limit of the frequency | count of use of the box B used in each clean room is set based on the acquired degree of contamination.

To set the upper limit of the number of times the box B is used in each clean room, based on the boron concentration acquired in the first step and the degree of contamination in the box B corresponding to the number of times the box B is used in the second step, For example, the graph shown in FIG. 2 is created. The horizontal axis of FIG. 2 shows the boron concentration measured in a plurality of different clean rooms (the boron concentration of each clean room acquired in the first step). The vertical axis in FIG. 2 shows the number of times the box B is transported in each clean room (the number of times the box B is used in each clean room in which the box B is transported from the cleaning apparatus to the vapor phase growth apparatus in the second step). Indicated. In addition, the meanings of ○ and × in FIG. 2 are as follows. ○ indicates that the height of the peak of the dopant concentration profile is 1.0 × 10 ¹⁴ atoms / cm ³ or less within the standard (within the standard desirable for an epitaxial wafer used for a semiconductor device). On the other hand, x indicates that the peak height of the dopant concentration profile exceeds 1.0 × 10 ¹⁴ atoms / cm ³ , which is out of specification. FIG. 2 shows the degree of boron contamination in the box B corresponding to the number of times the box B is used in the same clean room, in which the rows of O and X are arranged vertically. Therefore, the number of times of use of box B corresponding to ◯ located at the boundary between ◯ and X in the vertical column of FIG. 2 can be set as the upper limit number of times of box B in the corresponding clean room. In FIG. 2, the value on the horizontal axis corresponding to the column in which “O” and “X” are vertically arranged is the amount of boron in the clean room (a value corresponding to the boron concentration in the clean room) measured in the first step.

  The upper limit number of boxes B in each clean room is set as described above. When the upper limit number of boxes B is set in each clean room, a pair of the boron concentration acquired in the first step and the upper limit number of boxes B set in the second step is acquired from each clean room. And the correlation of the boron density | concentration of a clean room and the upper limit frequency | count of the box B used in a clean room is acquired based on the acquired several pair (4 pairs in FIG. 2). Specifically, in FIG. 2, the number of times of use of box B corresponding to the largest number of times of use of box B in each row in which ○ and × are vertically arranged, and the boron concentration of the clean room in which the box B is used For example, an approximate curve is created from the pair. The generated approximate curve is indicated by a broken line in FIG. 2, and this broken line is a correlation between the boron concentration in the clean room and the upper limit number of boxes B used in the clean room. If the boron concentration in the clean room where the upper limit number of the box B used in the clean room is not set is measured by the wafer exposure method as described above, the upper limit number of the box B corresponding to the boron concentration measured from the broken line in FIG. Is set (third step). Thereafter, in the clean room in which the upper limit number of boxes B is set in the third step, an epitaxial layer is grown on the substrate W transported by the box B within the upper limit number set in the third step to produce an epitaxial wafer. . In the embodiment of the present invention, the correlation between the upper limit number of the box B set based on the degree of boron contamination in the box B and the boron concentration in the clean room (approximate curve of the broken line in FIG. 2) is acquired. Therefore, if the boron concentration in the clean room can be acquired, the upper limit number of boxes can be managed so as to prevent the box B from being contaminated by boron. Specifically, when the boron concentration is acquired from a clean room in which the upper limit number of boxes B is not set, the upper limit number of boxes B used in the clean room in which the upper limit number is not set can be set from the broken line in FIG. Then, in a clean room in which the upper limit number is set, an epitaxial wafer in which the contamination of boron is suppressed can be manufactured by growing an epitaxial layer on the substrate W transported by the box B within the set upper limit number.

  In order to confirm the effect of the present invention, the following experiment was conducted. EXAMPLES Hereinafter, although an Example and a comparative example are given and this invention is demonstrated concretely, these do not limit this invention.

(Example)
The substrate W is exposed to each of the four clean rooms A, B, C, and D in different areas for 24 hours, and the contamination of the surface of the substrate W after the exposure is recovered with a hydrofluoric acid solution, and boron in the solution The amount of was measured by ICP-MS method. The amount of boron (atomics / cm ² ) measured in each clean room was 10.83 × 10 ¹⁰ , 34.39 × 10 ¹⁰ , 75.76 × 10 ¹⁰ , 100. 18 × 10 ¹⁰ was obtained. This amount of boron corresponds to the boron concentration in each of the clean rooms A, B, C, and D. Next, the following boxes were prepared in each clean room. Specifically, the inner carrier (which is made of polybutylene terephthalate) capable of storing 25 wafers having a diameter of 200 mm, a lid portion having a holding portion for fixing the wafer, and an opening closed by the lid portion is provided. A box having a main body (outer box (material is polypropylene)) for storing the carrier was prepared. And the prepared box was decomposed | disassembled into said three parts (an inner carrier, a cover part, and an outer box), and each part was wash | cleaned. At the time of cleaning, a first cleaning tank containing a 25 ° C. cleaning liquid adjusted so that the concentration of the ether-based surfactant was 3 to 5% and a second cleaning tank containing pure water were prepared. Next, each part was passed through a shower with pure water to perform rough cleaning of each part, and then each part was immersed in the first cleaning tank. Then, each part was taken out from the 1st washing tank, immersed in the 2nd washing tank, and rinsed. Then, after removing each part from the second washing tank, air-dry until the moisture is removed from the surface of each part, reassemble the parts after air-drying, and prepare a box with an internal boron concentration of 0.01 μg / L or less did. In each clean room, the prepared box is used to transport the substrate from the cleaning apparatus to the vapor phase growth apparatus a predetermined number of times, and the number of uses (the number of uses after cleaning) is 10, 20, 30, and 40 times. Box B was prepared. In each prepared box B, a substrate W having been cleaned with a chemical solution and having a dopant concentration of 5.0 × 10 ¹⁴ atoms / cm ³ was stored and stored for 24 hours in a constant temperature environment. Then, the dopant concentration profile of the outer peripheral part of the epitaxial wafer produced by growing an epitaxial layer on the stored substrate W was spread and measured by a resistance measurement method. From the measured dopant concentration profile, the peak height (the peak height indicated by the dopant concentration (atomics / cm ³ )) where the dopant concentration was locally reduced at and near the interface between the substrate W and the epitaxial layer was determined. . Then, the degree of contamination of the box B corresponding to the number of times the box B is used in each of the clean rooms A, B, C, and D was plotted in the same manner as the graph of FIG. Specifically, an approximated curve was created based on a plurality of pairs obtained from the clean room A, B, C, and D, respectively, as pairs of the upper limit number of times of the box B and the boron concentration in the clean room. The created graph is shown in FIG. 3, and in FIG. 3, an approximate curve showing the correlation between the upper limit number of boxes B and the boron concentration is indicated by a broken line.

Subsequently, the amount of boron (boron concentration) in the clean room E was measured for a new clean room E different from the clean rooms A, B, C, and D as in the clean rooms A, B, C, and D. The amount of boron in the clean room E was 58.77 × 10 ¹⁰ atoms / cm ² . Based on the amount of boron and the broken line in FIG. 3, the upper limit of the number of times the box B is used in the clean room E is set to 15 (see the arrow in FIG. 3).

In Example 1, the box B is used in the clean room E, and the number of times of use (the number of times of use after washing so that the internal boron concentration is 0.01 μg / L or less in the same manner as described above) is 15 times the upper limit. Prepared. Then, the substrate W having a chemical solution washed and a dopant concentration of 5.0 × 10 ¹⁴ atoms / cm ³ was stored in the prepared box B and stored for 24 hours in a constant temperature environment. Then, the dopant concentration profile of the outer peripheral part of the epitaxial wafer produced by growing an epitaxial layer on the stored substrate W was spread and measured by a resistance measurement method. From the measured dopant concentration profile, the height of the peak where the dopant concentration was locally reduced at the interface between the substrate W and the epitaxial layer and in the vicinity thereof (the height of the peak indicated by the dopant concentration (atomics / cm ³ )) was measured.

  In Example 2, the peak height of the dopant concentration profile was measured in the same manner as in Example 1 except that Box B was used 10 times.

(Comparative example)
In the comparative example, the height of the peak of the dopant concentration profile was measured in the same manner as in Example 1 except that 20 boxes B whose number of uses exceeded the upper limit were used.

FIG. 4 shows the peak heights measured in Examples 1 and 2 and the comparative example. In Examples 1 and 2, the peak height could be suppressed to 1.0 × 10 ¹⁴ atoms / cm ³ or less. In Example 2, the peak height could be suppressed to a level sufficiently lower than 1.0 × 10 ¹⁴ atoms / cm ³ . On the other hand, in the comparative example, the peak height of the dopant concentration was 1.0 × 10 ¹⁴ atoms / cm ³ or more. If a semiconductor element is manufactured based on an epitaxial wafer having a peak as in the comparative example, the characteristics of the manufactured semiconductor element may be adversely affected.

  From the above, the upper limit of the number of times of use of the box B can be easily obtained by examining the boron concentration in the clean room E without examining the amount of contamination in the box B corresponding to the number of times of use of the box B in the clean room E. did it. And the epitaxial wafer which suppressed the contamination by a boron was able to be manufactured by using the box B managed in this way.

  The embodiments of the present invention have been described above. However, the present invention is not limited to the specific description, and the illustrated configurations and the like can be appropriately combined within a technically consistent range. In addition, certain elements and processes may be replaced with known forms.

  W board B box

Claims (10)

A first step of acquiring a concentration of a specific impurity in each of the plurality of clean rooms in a clean room in which the substrate is stored and transported in a box;
Acquiring the degree of contamination by the specific impurities in the box corresponding to the number of times the box is used, which is the number of times the box has been transferred by storing the substrate, in each of the plurality of clean rooms. A second step of setting an upper limit number of times of use of the box for each of the plurality of clean rooms based on the degree;
Based on a plurality of pairs acquired from the respective clean rooms, the specific impurity concentration acquired in the first step and the upper limit number of pairs set in the second step are set to the specific impurity concentration and the upper limit number of times. Obtaining a correlation; and
A step of setting the upper limit number of times in the clean room in which the upper limit number is not set from the concentration of the specific impurity in the clean room in which the upper limit number is not set, and the correlation;
A box management method comprising: The substrate is a silicon single crystal substrate;
The box management method according to claim 1 , wherein the specific impurity is boron. The box management method according to claim 2 , wherein the substrate is the silicon single crystal substrate having a high resistivity doped with an N-type dopant. The box management method according to claim 3 , wherein the substrate is the silicon single crystal substrate doped with phosphorus, arsenic, or antimony as the N-type dopant and having a dopant concentration of 5 × 10 ¹⁴ atoms / cm ³ or less. . A first step of acquiring a concentration of a specific impurity in each of the plurality of clean rooms in a clean room in which the substrate is stored and transported in a box;
Acquiring the degree of contamination by specific impurities in the box corresponding to the number of times the box is used, which is the number of times the box has been transferred by storing the substrate, in each of the plurality of clean rooms, and acquiring each of the acquired A second step of setting an upper limit number of times of use of the box for each of the plurality of clean rooms based on a degree;
Based on a plurality of pairs acquired from the respective clean rooms, the specific impurity concentration acquired in the first step and the upper limit number of pairs set in the second step are set to the specific impurity concentration and the upper limit number of times. Obtaining a correlation; and
A third step of setting the upper limit number of times in the clean room where the upper limit number is not set, from the concentration of the specific impurity in the clean room where the upper limit number is not set, and the correlation;
Growing an epitaxial layer on the substrate transported by the box within the upper limit number set by the third step in the clean room where the upper limit number is set by the third step;
A method for producing an epitaxial wafer, comprising: The substrate is a silicon single crystal substrate;
The method for manufacturing an epitaxial wafer according to claim 5 , wherein the specific impurity is boron. The method for producing an epitaxial wafer according to claim 6 , wherein the substrate is the silicon single crystal substrate having a high resistivity doped with an N-type dopant. 8. The epitaxial wafer manufacturing method according to claim 7 , wherein the substrate is the silicon single crystal substrate doped with phosphorus, arsenic, or antimony as the N-type dopant and having a dopant concentration of 5 × 10 ¹⁴ atoms / cm ³ or less. Method. 9. The method for producing an epitaxial wafer according to claim 6 , wherein the growing step grows the epitaxial layer having a high resistivity doped with an N-type dopant. 10. 10. The epitaxial wafer according to claim 9 , wherein the growing step grows the epitaxial layer doped with phosphorus, arsenic, or antimony as the N-type dopant and having a dopant concentration of 5 × 10 ¹⁴ atoms / cm ³ or less. Production method.

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