JPH06295863A - Production of high resistance compound semiconductor - Google Patents

Abstract

PURPOSE:To produce a high resistance group III-V compound semiconductor with high reproducibility by placing a compound semiconductor crystal in an enclosed vessel transmitting the vapor of group V element but not transmitting the contaminant vapor, disposing a vapor source on the outside of the enclosed vessel, and performing heat treatment while preventing contamination due to Fe element. CONSTITUTION:An InP wafer 1 is placed in an enclosed vessel 10 made of high density graphite or the like which transmits the vapor of phosphorus but not transmit the vapor of Fe or iron phosphide. A red phosphorus 3 is disposed on the outside of the enclosed vessel 10 which is vacuum encapsulated in a silicon ampul 2 together with the red phosphorus 3. The ampul 2 is then heated uniformly thus increasing the resistance of the wafer 1. A red phosphorus 3 containing impurities by 0.1ppmw or less is preferably employed. Furthermore, a plurality of wafers 1, 1,... are brought into tight contact each other.

Description

Detailed Description of the Invention

[0001]

The present invention relates to OEIC, HEMT,
The present invention relates to a method for producing a high resistance compound semiconductor used for an electronic device such as an ion implantation type FET, and particularly to a technique for increasing the resistance by heat treatment.

[0002]

2. Description of the Related Art A III-V compound semiconductor has a resistivity of 10 ⁶
In order to increase the resistance to Ω · cm or more (that is, to make semi-insulating), a method of adding Fe, Co, Cr, or the like, which becomes a deep acceptor, is industrially used for a crystal containing Si or S that becomes a shallow donor. Has been. This increase in resistance is due to the mechanism of compensating the shallow donor with the deep acceptor. Therefore, it is said that the resistance cannot be increased unless the element serving as a deep acceptor is added so as to have a concentration higher than the concentration of the shallow donor contained in the crystal.

However, when Fe, Co, Cr or the like is doped to increase the resistance, it is desirable that the content concentration of these is as low as possible. Because, Fe, Co, Cr
, Etc., act as a deep acceptor, so in an ion-implanted electronic device (FET, etc.), the activation rate of ion-implanted shallow donor-type impurities is lowered, and a device operated at high frequency (OEIC, HEMT, etc.) In the above, since these elements diffuse in the epitaxial growth film and act as a trap, high frequency and high speed are hindered. Further, these elements such as Fe tend to segregate, the concentrations of Fe and the like differ between the upper and lower sides of the crystal, and the above activation rate becomes non-uniform, resulting in a low yield.

Conventionally, for example, as semi-insulating InP, F
e-doped InP is mainly used. But F
If the content concentration of e, etc. is less than 0.2 ppmw, the resistivity is 1
It becomes lower than 0 ⁶ Ω · cm, and the semi-insulating property deteriorates. In order to make it a semi-insulating crystal, the content concentration of Fe and the like had to be a certain concentration (0.2 ppmw) or more. Generally, III-V group compound semiconductors such as Fe and Cr
It has been considered that the reason why the resistivity decreases when the content concentration of etc. becomes low is that the impurity element serving as a shallow donor is present in the crystal as a residual impurity to that level. However, the present inventors believe that the mechanism for increasing the resistance of InP single crystal involves not only compensation by a shallow donor and a deep acceptor but also an electrically active point defect, and as a result of earnest research, It was found that by controlling the concentration of point defects by heat-treating the crystal, a semi-insulating III-V compound semiconductor can be obtained even if the impurity element concentration of the deep acceptor is much lower than before. .

As a result, the present inventor first found that the total content concentration of at least one of Fe, Co and Cr was 0.2 ppmw.
A technique for manufacturing a compound semiconductor having a resistivity of 10 ⁷ Ω · cm or more was proposed (Japanese Patent Laid-Open No. 2-69307).
issue). That is, as shown in FIG. 4, for example, in order to process a plurality of wafers at the same time, a method of aligning the wafers at substantially equal intervals using a jig and arranging them in the quartz ampoule 2 is applied. InP wafer (compound semiconductor) 1 containing 0.2 ppmw or less of Co, Cr or less, for example, cut from a single crystal produced by a melt growth method is vacuum-sealed in a quartz ampoule 2 and, for example, red phosphorus is contained in the quartz ampoule 2. 3 is arranged so that the partial pressure of phosphorus in the ampoule 2 is equal to or higher than the dissociation pressure of InP.
It is to heat at 40 ° C. According to our subsequent research, the invention of this prior application was undoped or F
It was found that even if the InP single crystal in which the content concentration of any one or more of the impurity elements of e, Co or Cr is 0.05 ppmw or less is heat-treated, it does not become semi-insulating.

Therefore, the present inventor has conducted further research, and as an improvement plan thereof, for example, as shown in FIG. 4, the red phosphorus 3 was left in the quartz ampoule 2 without intentionally adding impurities, and the residue was left. Fe and Co existing as impurities
Or, the total content concentration of any one or more of Cr is 0.05
By the method of heat-treating the InP wafer 1 having a ppmw or less in an atmosphere having a phosphorus partial pressure of more than 6 kg / cm ² , the total content concentration of these impurity elements is 0.05 ppmw or less, and the resistivity at 300K is A technique for producing a semi-insulating III-V group compound semiconductor (InP) having a mobility of more than 10 ⁶ Ω · cm and exceeding 3000 cm ² / V · s has been proposed (Japanese Patent Laid-Open No. 3-279299). The semi-insulating group III-V compound semiconductor (InP) to be obtained by the above-mentioned technique is an impurity contained in the crystal, particularly Fe, Co or Cr.
By setting the total content concentration of seeds or more to be 0.05 ppmw or less, it is possible to suppress the decrease in mobility due to the contained impurities and to set the mobility to a desired value or more. Heretofore, considerable attention has been paid to the contamination of impurities in the heat treatment process described above. For example, a vapor source material (red phosphorus) used to generate a Group V element (phosphorus) vapor has at least a purity of 99.99.
About 99% was used, and most of them had a purity called "6N". Those having the above-mentioned purity have an impurity element content concentration of more than 0.1 ppmw and 1 ppmw or less.

[0007]

However, in the invention proposed in Japanese Patent Laid-Open No. 3-279299 by the subsequent research conducted by us, the reproducibility of the electrical characteristics is poor except for the resistivity as described below. I understood. That is, 900
In an atmosphere having a phosphorus partial pressure of 15 atm (about 15 kg / cm ² ) at 60 ° C., 6 sets (one set) of InP wafers containing 0.05 ppmw or less of the concentration of one or more impurity elements of Fe, Co, and Cr. After several heat treatments were performed for 6 runs of heat for 20 hours per run, the mobility, which is one of the electrical characteristics of the wafer, was measured for each run as shown in FIG. Not only did they vary among different runs, but they also varied over the same run. Furthermore, there were a considerable number of those whose mobility did not reach the desired value of 3000 cm ² / V · s or more.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a method of manufacturing a high-resistance compound semiconductor excellent in reproducibility of electrical characteristics.

[0009]

In order to investigate the cause of the above-mentioned variation in mobility, the present inventor has made InP and GaP single crystals that have not been subjected to any doping treatment or heat treatment, and cut them out from the above single crystals. The elemental analysis of the wafer obtained by heat treatment as described above was performed by the GDMS method (glow discharge mass spectrometry). As a result, as shown in Table 1, the Fe element concentration of InP was less than 0.
Less than 002 ppmw (analysis detection lower limit value) was 0.008 to 0.089 ppmw after heat treatment, and for GaP, less than 0.005 ppmw before heat treatment was 0.68 to 1.89 after heat treatment.
It was as high as 4 ppmw, and it was found that Fe element was mixed into the crystal from the outside during the heat treatment in each case. That is, it was found that Fe mixed in during the heat treatment reduced the mobility and caused variations.

[Table 1]

Contamination sources that have generated this Fe element are those near the crystal, such as the quartz ampoule 2 shown in FIG. 4, a quartz jig 4 such as a spacer, the heater 5, the furnace member 6, and the quartz ampoule 2. It was thought that it was one of the placed red phosphorus 3, and various experiments described below were conducted in order to identify the pollution source. Fe element concentration before heat treatment is 0.002
InP wafers that were less than ppmw were 5 atm, 15 atm, 25
At each phosphorus partial pressure of atm, 4 at 985 ° C., which is a heat treatment condition that can promote mixing of Fe into the crystal by diffusion.
As a result of performing elemental analysis by performing heat treatment for 0 hour, it was found that, as shown in Table 2, the higher the phosphorus partial pressure, the higher the Fe concentration in the crystal. Moreover, the purity is 99.999.
9% (concentration of contained impurity element is 1 ppmw.
Abbreviated as "6N". ) And 99.99999% (concentration of contained impurity element is 0.1 ppmw. Hereinafter, “7N”)
Is abbreviated. ), The elemental analysis was carried out for 40 hours at a phosphorus partial pressure of 25 atm at 985 ° C. As a result, as shown in Table 3, the lower the purity of red phosphorus, the higher the Fe concentration in the crystal. I found out that.

[Table 2]

[Table 3]

From these results, it was estimated that the source of contamination of Fe element was red phosphorus 3. Further, elemental analysis was performed on a single crystal of GaAs and a wafer obtained by cutting the single crystal and subjecting it to a heat treatment without using red phosphorus at an arsenic partial pressure higher than the dissociation pressure of GaAs. As a result, as shown in Table 1, F
The concentrations of the e element were all lower than the lower limit of analysis and detection, and no Fe element was mixed into the crystal during the heat treatment. Therefore, it was found that there was no Fe element contamination under the condition without red phosphorus, and there was Fe element contamination only under the condition with red phosphorus, and it was found that the source of Fe element contamination was red phosphorus 3. That is, it was found that it was an Fe element contained as an impurity in the red phosphorus 3.

The present invention has been made based on the above findings, and in manufacturing a high-resistance compound semiconductor by heat treatment, the crystal of the compound semiconductor in the ampoule and the highest element among the plurality of elements constituting the compound semiconductor are the highest. A vapor source material for maintaining a partial pressure of an element having a saturated vapor pressure in the ampoule at a predetermined pressure higher than the dissociation pressure of the compound semiconductor, in encapsulating and performing heat treatment, a plurality of elements constituting the compound semiconductor A gas consisting of an element having the highest saturated vapor pressure among the plurality of elements constituting the compound semiconductor having an atomic radius larger than the atomic radius of the element having the highest saturated vapor pressure, The crystal is placed in a closed container made of a material that is impermeable to a gas containing an element that serves as a deep acceptor in the compound semiconductor. Is and proposes to carry out heat treatment by enclosing said closed container and said vapor source material into the ampoule. Further, the present invention provides the compound semiconductor according to III
In the case of a group V compound semiconductor, a vapor source material composed of a group V element which is a constituent element of the III-V compound semiconductor is used, and while maintaining a partial pressure of the group V element in the ampoule at a predetermined pressure, The gas composed of the group V element is permeable,
In addition, the crystal of the III-V group compound semiconductor is placed in a closed container made of a material that does not allow a gas containing an element having an atomic radius larger than that of the V group element to be a deep acceptor in the compound semiconductor to pass through. It is proposed to put the vapor source material and the hermetically sealed container in an ampoule and perform heat treatment.

Specifically, a material having a layered structure or porous material such as high density (density of 1.77 g / cm ³ or more) graphite, silicon carbide, boron nitride, etc., which is chemically stable at least at the heat treatment temperature. It is made of a material that allows phosphorus vapor (P atoms or P ₄ , P ₂ molecules) to pass through, but does not allow contaminated vapors such as Fe and iron phosphide (Fe _x P _y ) to pass through. Put a wafer, put red phosphorus as a vapor source material outside the closed container, vacuum-enclose the closed container and red phosphorus in a quartz ampoule, and uniformly heat the ampoule to increase the resistance of the wafer. Let In addition, it is desirable that the impurity element content concentration of red phosphorus is 0.1 ppmw or less, that is, the phosphorus purity is 7N or more. Further, when heat-treating a plurality of wafers at the same time, it is more preferable to bring the surfaces of the wafers into close contact with each other. In this case, dummy wafers may be arranged at both ends of the aligned wafer group, or other members may be brought into close contact with the wafers at both ends so that the outer surfaces of the wafers are not exposed. Materials suitable for use in producing the above-mentioned closed container, that is, high-density graphite, silicon carbide, and boron nitride are artificially produced by a high-temperature reaction, and are oriented in a layered structure of fine crystals, or have a high degree of orientation. It is obtained as a polycrystalline body that forms crystal grain boundaries of high purity, and is usually a porous body. When these materials are viewed on an atomic scale, there are microscopic gaps in the grain boundaries where the lattice arrangement is disturbed, and molecules (or atoms) made of other elements can invade from the outside, It is a kind of porous / adsorption material that causes physical or chemical adsorption. Furthermore,
In a substance having a layered structure such as graphite, an element more positive than the element constituting the substance intercalates into the layer to form a compound called an intercalation compound that is unique to the layered structure. For example, in graphite composed of carbon (C), a positive metal element such as an alkali metal element forms a stable insertion compound. In addition, a compound having a conjugated double bond (or a substance having a similar structure) such as an aromatic compound
And a transition metal element such as Fe, Co, or Cr having a d-electron as the outermost nuclear electron stably forms a special compound called a sandwich compound. This compound has a structure in which a planar compound having a conjugated double bond (or a substance having a similar structure) has atoms of a transition metal element oriented in parallel from above and below. On the other hand, group V elements such as phosphorus are elements that are more negative than carbon elements and do not form insertion compounds or sandwich compounds.

[0014]

According to the above-mentioned means, the partial pressure in the ampoule of the element having the highest saturated vapor pressure among the plurality of elements forming the compound semiconductor is maintained at a predetermined pressure higher than the dissociation pressure of the compound semiconductor. , When heat-treating a crystal of a compound semiconductor, the vapor of the element having the highest saturated vapor pressure of the plurality of elements constituting the compound semiconductor generated from the vapor source can pass through the closed container containing the crystal, so that vapor The partial pressure in the closed container of the element having the highest saturated vapor pressure among the plurality of elements constituting the compound semiconductor is also equal to the partial pressure in the ampoule, that is, a predetermined value higher than the dissociation pressure of the compound semiconductor. Kept at the pressure of. On the other hand, a gas containing an element having an atomic radius larger than the atomic radius of the element having the highest saturated vapor pressure among the plurality of elements constituting the compound semiconductor, which element becomes a deep acceptor in the compound semiconductor, that is, a contaminated vapor Cannot penetrate the material of which the closed container is made to penetrate into the closed container. Therefore, it is possible to prevent the crystals in the closed container from being contaminated by the contaminated vapor from the outside of the closed container during the heat treatment. Specifically, when applied to the production of a high resistance III-V group compound semiconductor, since the vapor of the group V element from the vapor source can pass through the closed container, the vapor is used to divide the group V element into the closed container. The pressure is maintained at a predetermined pressure higher than the dissociation pressure of the III-V compound semiconductor. On the other hand, since a contaminated vapor composed of Fe or a compound containing an Fe element having an atomic radius larger than the atomic radius of the group V element cannot enter the closed container, during the heat treatment, the III-V group compound semiconductor in the closed container Contamination of the crystal with Fe element is suppressed. Therefore, the increase in the Fe element concentration in the crystal after the heat treatment can be suppressed to an extremely low level. By applying a predetermined partial pressure of the group V element and performing heat treatment, the crystal can have a high resistance. For example, according to the invention proposed by the present applicant in Japanese Patent Application Laid-Open No. 3-279299, the total content concentration of at least one impurity element of Fe, Co or Cr is 0.05 pp.
By using InP single crystal of less than mw as a starting material and applying a predetermined phosphorus partial pressure, that is, a phosphorus partial pressure of 6 kg / cm ² or more, and performing heat treatment, one or more of Fe, Co, and Cr are selected. The total content concentration of impurity elements is 0.05ppmw or less, the mobility exceeds the desired 3000 cm ² / Vs, 300K
It is possible to manufacture a high resistance InP single crystal having a resistivity of 10 ⁶ Ω · cm or more.

Further, by using a vapor source material consisting of a Group V element having a purity of 7 N or more, that is, an impurity element content concentration of 0.1 ppmw or less, the amount of polluted vapor generated from the vapor source can be suppressed to an extremely small amount. Therefore, the amount of Fe element mixed in the crystal can be suppressed. Further, when the crystal is in the form of a wafer, by making the surfaces of a plurality of wafers in close contact with each other, even if the contaminated vapor leaks into the closed container, it is exposed to the contaminated vapor. Since only the outer peripheral edge of the wafer is exposed, the contact area with the contaminated vapor is extremely small, and the amount of Fe element mixed in is very small. Moreover, the area where the electronic device is manufactured, that is, most of the wafer surface inside the outer peripheral edge is not contaminated, and is not contaminated by scraping the outer peripheral edge, for example, when the surface is mirror-finished. A high resistance wafer is obtained.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First, an example of a closed container used for carrying out the present invention is shown in FIG. 1 and described. As shown in the figure, the hermetically sealed container 10 is composed of a cylindrical body 11 for accommodating the wafer 1 and a pair of lids 13 and 13 for closing both ends thereof. The vapor of iron oxide is impermeable. That is, the cylindrical body 11 and the lid body 13 are made of a material having a layered structure such as high density graphite having a density of 1.77 g / cm ³ or more, or a porous body.

The lid 13 has a cylindrical body 11 and a packing 15
And the like. A plurality of wafers 1, 1, ... Can be brought into a state where their surfaces are in close contact with each other by a fixing jig 18 provided inside the closed container 10. At that time, in order to prevent the wafer 1 from being damaged due to an excessive force, a contact plate portion 17 that contacts the wafer 1 is provided. In addition, the contact plate portion 17, the fixing jig 18, and the packing 15
Needless to say, is made of a material that does not contaminate the wafer 1.

Next, a concrete description will be given with reference to examples and comparative examples. (Example 1) Thickness cut out from a single crystal in which the content concentrations of Fe, Co, and Cr, which were pulled up from the InP raw material polycrystal by the liquid sealed Czochralski method, were all lower than the analytical detection lower limit (0.002 ppmw). A plurality of 0.5 mm thick InP wafers (thin plates) 1, 1, ... Are arranged in the cylindrical body 11 of the graphite hermetic container 10 at intervals using a quartz jig 4 serving as a spacer. Then, the cylindrical body 11 has lids 13, 13
Was attached and the inside of the container 10 was sealed.

Subsequently, as shown in FIG. 2, the closed container 10 and red phosphorus 3 having a purity of 6N are placed in a quartz ampoule 2 and the inside of the quartz ampoule 2 is 1 × 10 ⁻⁶ torr (about 1.3). × 1
After evacuation to 0 ^-9 kg / cm ² ), the opening of the quartz ampoule 2 was sealed with an oxyhydrogen burner. At this time, according to the invention proposed in Japanese Patent Laid-Open No. 3-279299, the amount of red phosphorus 3 is set so that the phosphorus partial pressure becomes 6 kg / cm ² (about 6 atm) or more, for example, the phosphorus pressure in the quartz ampoule 2 is The heat treatment temperature was adjusted to 25 atm. Next, this quartz ampoule 2 was placed in a horizontal heating furnace and heated at a heat treatment temperature of 985 ° C. for 4 hours.
After heating and holding for 0 hour, it was cooled at a temperature lowering rate of about 30 ° C./min. The horizontal heating furnace is a closed type that can pressurize up to a pressure of 100 kg / cm ² , and at the time of raising and lowering temperature, an argon gas having a pressure corresponding to the phosphorus partial pressure corresponding to the temperature is introduced into the heating furnace. The balance between the pressure inside and outside the quartz ampoule 2 was maintained to prevent the quartz ampoule 2 from being broken. The jigs such as the ampoule 2 and the spacer were made of fused silica.

Comparative Examples 1 to 3 For comparison, the following 3
An experiment was conducted. In Comparative Examples 1 and 2, heat treatment was performed without using the closed container 10, as shown in FIG. The purity of phosphorus was 6N in Comparative Example 1 and 7N in Comparative Example 2.
In Comparative Example 3, as shown in FIG. 6, an unsealed container 20 made of pBN (pyrolytic boron nitride) (a cylindrical body for housing a wafer and a pair of lids for closing both ends thereof) is configured. ) And red phosphorus 3 having a purity of 6N. Other conditions were the same as in Example 1 above.

Regarding the wafers obtained in Example 1 and Comparative Examples 1 to 3, F contained in the wafer after the heat treatment
The concentration of element e was examined by elemental analysis. The results are shown in Table 4.
Shown in. Comparing Example 1 and Comparative Example 1, the concentration of Fe element is lower in Example 1 (Comparative Example 1
It is about / 3 to 1/2. ), The sealed container 10 made of graphite is effective for the contamination of the wafer crystal by the Fe element contained in the red phosphorus 3 as the impurity element. That is, it can be seen that the closed container 10 suppresses the entry of the contaminated vapor of Fe or the compound containing the Fe element into the closed container 10. In addition, by comparing Example 1 and Comparative Example 2, it can be seen that the effect of preventing contamination by the closed container 10 is equivalent to setting the purity of phosphorus to 7N. Furthermore, by comparing Example 1 with Comparative Example 3, no clear pollution prevention effect was observed in the unsealed container 20 made of pBN, and it is preferable that the sealed container 10 is made of graphite. It can be seen that it is.

[Table 4]

(Reference Example) In order to investigate the effect of the purity of phosphorus, that is, the content concentration of the impurity element, a heat treatment was performed under the same conditions as in Comparative Example 3 using red phosphorus having a purity of 7N. In addition, as shown in FIG. 6, the same unsealed container 20 made of pBN as in Comparative Example 3 was used. The quartz ampoule 2 and the quartz jig 4 were made of synthetic quartz having a higher purity than fused quartz. (Comparative Example 4) For comparison, red phosphorus having a purity of 6N was used. In addition, as shown in FIG. 4, a container for storing the wafer was not used. Other conditions were the same as in the above reference example.

The concentration of Fe element contained in the wafers obtained in Reference Example and Comparative Example 4 was examined by elemental analysis. The results are shown in Table 4. From the table, comparing the reference example with the comparative examples 3 and 4, as a result of making the purity of phosphorus 7N, the concentration of Fe element contained was 1/2 or less, and the contamination of Fe element was 7N. It turns out that it is effective to use red phosphorus having the above-mentioned purity.

FIG. 3 is a graph in which the measured values of the Fe element content in Tables 4 and 2 are plotted against the phosphorus partial pressure. In the figure, ○ indicates that the purity of phosphorus is 6
N and without using the graphite closed container 10, □ indicates the phosphorus purity is 6N and uses the graphite closed container 10, and Δ indicates the phosphorus purity is 7N and the graphite closed container. The container 10 is not used, respectively. From the figure, regarding the pollution prevention effect,
It is found that the purity of phosphorus is 7 N or more, or it is effective to use the closed container 10 made of graphite,
By performing heat treatment using either of them, a high resistance compound semiconductor can be manufactured with excellent reproducibility. Furthermore, in addition to the use of the closed vessel 10 made of graphite, if red phosphorus having a purity of 7N or more is used at the same time, the contamination by Fe element can be extremely effectively suppressed by the synergistic effect of both, and the high resistance III-V group It is judged that the compound semiconductor can be manufactured with higher reproducibility.

The hermetically sealed container 10 is not limited to the one used in the above embodiment, and the shape of the hermetically sealed container 10 may be changed as long as the wafer 1 can be accommodated and can be closed by a lid or the like, and the material thereof can be changed. Any material may be used as long as it is not limited to graphite as long as it is permeable to phosphorus vapor but impermeable to contaminated vapor such as Fe and iron phosphide. For example, silicon carbide or boron nitride may be used.

In the above embodiment, the present invention is
Although the example applied to the heat treatment of nP has been described, GaP
Of course, the present invention can be applied to the heat treatment of compound semiconductors (including those having a mixed crystal composition) in which the group V element constituting the element is P. Furthermore, the heat treatment conditions such as temperature, V group element partial pressure (phosphorus partial pressure), and treatment time are not limited to the conditions of the above-mentioned embodiment,
Even if various changes are made, it is possible to manufacture a high-resistivity III-V group compound semiconductor with excellent reproducibility while suppressing contamination by contaminated vapor (such as Fe element). Further, in the step of producing a high resistance II-VI group compound semiconductor, an element having the highest saturated vapor pressure among a plurality of elements constituting the II-VI group compound semiconductor, that is, a vapor source material consisting of a Group II element. II
-Heat treatment is performed while maintaining a predetermined pressure higher than the dissociation pressure of the Group VI compound semiconductor. At this time, the gas consisting of the group II element is permeable, and is an element having an atomic radius larger than the atomic radius of the group II element contaminating the group II-VI compound semiconductor, and the group II-VI compound. When a crystal is placed in a closed container made of a material that is impermeable to a gas that is an element that serves as a deep acceptor in a semiconductor, it is an element having an atomic radius larger than that of the Group II element.
In the II-VI group compound semiconductor, a gas containing an element that serves as a deep acceptor, that is, a contaminated vapor can be suppressed from entering the closed container, and contamination can be suppressed.

Furthermore, the wafers 1, 1,
If the surfaces of ... Are brought into close contact with each other, even if vapor such as Fe or iron phosphide intrudes into the closed container 10, since only the outer peripheral edge of the wafer 1 is exposed, the contamination thereof is caused. Only the outer periphery is exposed to steam. In other words, the contact area with the contaminated vapor becomes extremely small, the amount of Fe element mixed in is very small, and most of the area of the wafer surface where the electronic device is manufactured is not contaminated, so after the heat treatment, If the peripheral edge is shaved off, a high-resistance wafer having no contamination can be obtained. Therefore, the contamination with Fe element can be suppressed very effectively, and the high resistance III-V group compound semiconductor can be manufactured with more excellent reproducibility. In this case, if phosphorus having a purity of 7N or more is used, the amount of Fe element mixed during the heat treatment can be further reduced to almost zero, and the reproducibility is further improved.

[0028]

According to the method for producing a high resistance compound semiconductor according to the present invention, the vapor of the element having the highest saturated vapor pressure among the plurality of elements constituting the compound semiconductor is transmitted, but the compound semiconductor is constituted. A gas containing an element having an atomic radius larger than the atomic radius of the element having the highest saturated vapor pressure among the plurality of elements, the element being a deep acceptor in the compound semiconductor, that is, a contaminated vapor in a closed container that is impermeable. By placing a crystal of the compound semiconductor and arranging a vapor source outside the closed container, the partial pressure in the closed container of the element having the highest saturated vapor pressure among the plurality of elements forming the compound semiconductor is concerned. It is possible to maintain a predetermined pressure higher than the dissociation pressure of the compound semiconductor and perform heat treatment while suppressing contamination by contaminated vapor. When applied to the step of producing a high resistance III-V compound semiconductor, the crystal of the III-V compound semiconductor material is placed in a closed container which allows the vapor of the group V element to permeate but does not permeate the contaminated vapor, and By disposing the vapor source outside the closed container, it is possible to apply a predetermined partial pressure of the group V element to the crystal of the III-V group compound semiconductor and perform heat treatment while preventing contamination by the Fe element. When the content concentration of impurities such as 0.05ppmw or less,
Mobility is above the desired value and resistivity is 10 ⁶ Ω · cm
The high resistance III-V group compound semiconductor described above can be manufactured with good reproducibility.

[Brief description of drawings]

FIG. 1 is a schematic view showing an example of a closed container used in a manufacturing method according to the present invention and a state where wafers are stored in the container.

FIG. 2 is a schematic view of a state in which the closed container is installed in a heating furnace.

FIG. 3 is a characteristic diagram showing the relationship between the phosphorus partial pressure in the heat treatment and the Fe element content concentration in the wafer after the heat treatment.

FIG. 4 is a schematic view showing a state where a wafer is installed in a heating furnace in a conventional heat treatment method.

FIG. 5 is a characteristic diagram showing the mobility of a wafer obtained by a conventional heat treatment method.

FIG. 6 is a schematic view showing a state where an unsealed container is installed in a heating furnace.

[Explanation of symbols]

 1 Wafer (Crystal of III-V Group Compound Semiconductor) 2 Quartz Ampoule (Ampule) 3 Red Phosphorus (Vapor Source Material) 10 Closed Container

Claims (5)

[Claims] 1. A crystal of a compound semiconductor in an ampoule, and a partial pressure in the ampoule of an element having a highest saturated vapor pressure among a plurality of elements constituting the compound semiconductor is higher than a dissociation pressure of the compound semiconductor. At the time of performing heat treatment by encapsulating the vapor source material which is kept at a pressure of, the gas composed of the element having the highest saturated vapor pressure among the plurality of elements constituting the compound semiconductor is permeable, and constitutes the compound semiconductor. A gas containing an element having an atomic radius larger than the atomic radius of the element having the highest saturated vapor pressure among the plurality of elements, the element being a deep acceptor in the compound semiconductor, is contained in a closed container made of a material that is impermeable. A high-resistance compound characterized by containing crystals, enclosing the vapor source material and the closed container in an ampoule, and performing heat treatment. Semiconductor manufacturing method. 2. The method for producing a high resistance compound semiconductor according to claim 1, wherein the compound semiconductor is a III-V group compound semiconductor, and the vapor source material is a V group element. 3. The material for forming the closed container is one or more materials selected from the group consisting of high-density graphite, silicon carbide and boron nitride. A method for producing the high-resistance compound semiconductor described. 4. The vapor source material has an impurity element content concentration of 0.1 ppmw or less and is composed of an element having the highest saturated vapor pressure among a plurality of elements constituting the compound semiconductor. The method for producing a high resistance compound semiconductor according to claim 1, 2, or 3. 5. The production of a high-resistance compound semiconductor according to claim 1, wherein a crystal of a compound semiconductor composed of a plurality of the thin plates is placed with the surfaces of the crystals in contact with each other. Method.