JPS5856425A - Formation of insulating film on compound semiconductor crystal - Google Patents

Abstract

PURPOSE:To obtain an insulating film having excellent interface characteristics and a high quality, by a method wherein a V-family element nitride formed through a reaction between a source gas including a V-family element and ammonia gas is deposited on a compound semiconductor crystal having a V- family element. CONSTITUTION:A reaction tube 5 is heated to about 200 deg.C to etch the surface of an InP crystal 7 with hydrogen chloride gas. After cleaning, phosphine (PH3) gas and ammonia (NH3) gas are made to flow into the reaction tube 5 in the approximate proportion 1:1. Then, the phosphine (PH3) gas and the ammonia (NH3) gas react with each other in high-temperature regions at both side portions in the reaction tube 5 to form phosphoric nitride (P3N5) gas. While the surface of the InP crystal 7 is thermally nitrided by a reactive nitrogen (N) gas generated in this case, phosphoric nitride (P3N5) is uniformly deposited on the InP crystal 7, thereby to form an insulating film 8.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for forming an insulating film on a compound semiconductor crystal, in which an insulating film made of a nitride of a group V element is formed on a compound semiconductor crystal containing a group V element.

In the method of forming such an insulating film, group V elements in the compound semiconductor crystal easily evaporate at high temperatures.

It was not possible to form the desired dredged insulating film at high temperatures. For this reason, attempts have been made to form an insulating film at low temperatures, but even in that case it has not been possible to form a satisfactory insulating layer.

Therefore, the present invention aims to propose a novel method free from the above-mentioned drawbacks, which will become clear from the following description of embodiments of the present invention.

FIG. 1 shows an example of an apparatus for accomplishing the method of the invention, 1
2 is a pure nitrogen gas source, 2 is a hydrogen chloride gas source, 5 is a phosphine gas source, 4 is for ammonia (gas source), 5 is a quartz reaction tube, 6 is a heating source, and 7 is an InP crystal.

First, the inside of the reaction tube 5 is replaced with nitrogen gas from the nitrogen gas source 1, and then 20 liters of hydrogen chloride gas from the hydrogen chloride gas source 2 is supplied into the reaction tube 5, and the reaction tube 5 is replaced by a heating source 6. 200
℃ to etch and clean the surface of the InP crystal 7.Next, the gas in the reaction tube 5 is replaced with nitrogen gas from the nitrogen gas source 1, and hydrogen chloride gas is removed from the tube 5. .

Next, phosphine gas and ammonia gas are caused to flow into the tube 5 from the gas sources 5 and 4 at a ratio of about 1:1. In this case, the temperature distribution of the reaction tube 5.

As shown in the diagram, the temperature on both sides of P3N4 due to the reaction between phosphine gas and ammonia gas. As a result, phosphine and ammonia are generated in the high temperature region inside the tube 5. In addition to producing P3N5, excess phosphorus P and reactive nitrogen N are generated. All of these are diffused by heat and flow toward low temperature regions.

On the other hand, InP crystal 7 is placed in the low temperature region of tube 5.

Therefore, the above-mentioned product 381 effectively flows onto the InP crystal 7 and accumulates there. As a result, since the concentration of reactive nitrogen N is high, thermal nitridation progresses effectively. Furthermore, since the partial pressure of phosphorus P is increased by the InP crystal 7', deterioration due to thermal decomposition of the crystal can be avoided. Furthermore, P and N5, which are gas reaction products, are deposited uniformly on the InP crystal to form an insulating layer. Of course, the nitrogen atoms diffuse through the P3N5MK and reach the crystal substrate, and nitridation of the crystal proceeds in parallel.

FIG. 2 shows the results of experimentally determining the temperature distribution of the present invention, particularly the range of suitability for selecting the high-temperature side temperatures on both sides and the temperature at the central valley from each viewpoint. The high temperature region is determined by the P and N5 generation temperature, and in this case is 850° C. or higher. On the other hand, the temperature in the valley was 500 to 650°C.

Moreover, FIG. 3 shows the relationship between growth time and grown film thickness. The film thickness depends almost linearly on time. In this amount of time, only a very thin film of 100X or less can be obtained by heat treatment alone, but a sufficiently thick film cannot be obtained due to the P3N5 attack. It was found that the membrane thus obtained was dense and had excellent chemical resistance.

Furthermore, Figure 4 shows the capacitance-voltage (0-V) curve measured with an MI8 (metal-insulator-semiconductor) diode compared to the conventional O
The characteristics were compared with those of an MJ8 diode made of a VD film.

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”'b is 31 force shi-2ri, )4 Fig. 1 Fig. 2, = Pay IT ('C) Fig. 3 Between Tyt (hr) 箪4 Fig.-6-4-20246 Electric charge (v) Face ■) Procedural amendment dated October 6th, 1982 Haruki Shimada, Commissioner of the Patent Office 1. Description of the case 2. Name of the invention Method of forming an insulating film on a compound semiconductor crystal 3. Related Patent Applicant 4, Attorney 8 Contents of the Amendment Description as attached (Full text corrected) 1. Title of the invention Method for forming an insulating film on a compound semiconductor crystal 2. Claims Reaction region: A compound semiconductor crystal that forms an insulating film made of a nitride of a group V element on a compound semiconductor crystal containing a group V element arranged in the reaction region by reacting a source gas containing a group V element with ammonia gas. In the method of forming an insulating film on the top, the temperature distribution of the reaction region is set to a temperature distribution in which the center part is lower than the both sides, and the temperature of both sides of the reaction region is set to include the group V element. The temperature is higher than the temperature at which the source gas and the ammonia gas react to form a nitride of the M group element, the temperature of the central portion is 200° C. or more lower than the temperature of the both sides, and the compound semiconductor crystal is A method for forming an insulating film on a compound semiconductor crystal, characterized in that the north gas containing the group V element and the ammonia gas are reacted with the ammonia gas while the ammonia gas is placed in the central part.

3. Detailed Description of the Invention The present invention provides a compound semiconductor crystal having a group V element;
The present invention relates to a method for forming an insulating film on a compound semiconductor crystal, which forms an insulating film made of a nitride of a group element.

Conventionally, as a method for forming an insulating film on such a compound semiconductor crystal, a source gas containing a group I element and ammonia gas are reacted in a reaction region, and a compound semiconductor having a group V element disposed in the reaction region is formed. A method has been proposed in which an insulating film made of a nitride of a group V element is formed on a crystal.

Conventionally, in such a method, the temperature of the reaction region is set to be higher than that of other regions, the temperature distribution of the reaction region is made into a flat distribution or a trapezoidal distribution, and in this case, the temperature of the reaction region is The temperature is increased by the reaction between source gas and ammonia gas.
The temperature is higher than the temperature at which nitrides of group elements are formed,
It has been common practice to have a compound semiconductor crystal placed in the center of a reaction region having such a temperature, and to cause the north gas and ammonia gas to react.

However, in the case of such conventional methods, the compound semiconductor crystal is heated to a temperature higher than the temperature at which the source gas and the ammonia gas react to form nitrides of Group V elements. The group V elements that make up the nitride evaporate unnecessarily, making it impossible to form an insulating film made of a nitride of group V elements with the desired excellent properties between the compound semiconductor crystal and the compound semiconductor crystal. It was something.

For this reason, conventionally, in the conventional method described above, a gas containing a group V element is introduced into the reaction region to obtain a partial pressure of the gas of the group V element on the compound semiconductor crystal. A method has been proposed in which the evaporation of Group V elements constituting the crystal is suppressed.

However, in the case of such a method, the gas containing group V elements flows to other regions other than the reaction region because the temperature of the other region other than the reaction region is lower than that of the reaction region, so that on the compound semiconductor crystal, V that can be constructed from compound semiconductor crystals
A sufficient partial pressure of the V group element gas cannot be obtained to suppress the evaporation of the group elements. Therefore, even in the case of such a method, it has not been possible to form an insulating film made of a nitride of a group V element so as to have the expected excellent characteristics with the compound semiconductor crystal.

Therefore, the present invention proposes a novel method for forming an insulating film on a compound semiconductor crystal without the above-mentioned drawbacks, and this will become clear from the description of embodiments of the present invention below.

FIG. 1 shows an example of an apparatus for achieving the present invention, in which 1 is a nitrogen gas source from which pure nitrogen gas is obtained, 2 is a hydrogen chloride gas source from which hydrogen chloride gas is obtained, and 5 is a source gas. 4 is an ammonia gas source from which ammonia (NH,) is obtained, 5 is a reaction tube made of quartz, and 6 is arranged around the reaction tube 5. A heating source 7 heats the reaction tube 5, which is a compound semiconductor crystal containing a group V element, and 7 is a heat source that heats the reaction tube 5.
An nP crystal is shown.

In one example of the present invention, first, nitrogen gas is introduced into the reaction tube 5 from the nitrogen gas source 1, and the inside of the reaction tube 5 is replaced with nitrogen gas. Next, a hydrogen chloride gas source 2 is added into the reaction tube 5.
Hydrogen chloride gas is supplied to mix 20 g of hydrogen chloride gas into the nitrogen gas inside the reaction tube 5.

Next, the reaction tube 5 is heated to about 200°C using the heat source 6, and the In
The surface of P crystal 7 is etched with hydrogen chloride gas, and I
Clean the surface of nP crystal 7.

Next, nitrogen gas from the nitrogen gas source 1 is introduced into the reaction tube 5 to replace the inside of the reaction tube 5 with nitrogen gas, thereby removing hydrogen chloride gas from the inside of the reaction tube 5.

Next, phosphine gas and ammonia gas are added into the reaction tube 5 from the source gas source 6 and the ammonia gas source 4 at a ratio of about 1=1.
It will be made to flow at the rate of . In this case, as shown in the diagram, the temperature distribution inside the reaction tube 5 is such that the temperature on both sides increases due to the reaction between phosphine gas and ammonia gas. ) Each law distribution is such that the temperature is 850° C. or higher at which gas is generated, and the temperature at the center is 200° C. or more lower than the temperature at both parts a, for example, 590° C.2. In such a case, phosphine gas and ammonia gas react in the high temperature regions on both sides of the reaction tube 5, and 5-nitrogen (1z phosphorus (P, N5) gas is produced. In this reaction, excess phosphorus (P) gas and reactive nitrogen (・N) gas are generated in this region.
gas, phosphorus (P) gas, and reactive nitrogen (N) gas are all transferred to the low temperature region in the center due to the temperature gradient between the high temperature regions on both sides and the low temperature region in the center of the reaction tube 5. It flows in that direction and stays there.

On the other hand, InP crystal 7 is placed in a low temperature region in the center of reaction tube 5. For this reason, the above-mentioned pentaphosphorous nitride (P, N5), @(P), and reactive nitrogen (N
) gas is effectively present on the InP crystal 7. As a result, while the surface of the InP crystal 7 is thermally nitrided by the reactive nitrogen (N) gas, a 5 phosphorus (P, N5') is uniformly deposited in one layer, thereby forming an insulating film 8 made of 5 phosphorous nitride on the InP crystal center.In this case, the Since it has a gas partial pressure, the phosphorus (P) constituting the InP crystal 7 does not evaporate unnecessarily, and therefore the insulating film 8 has a well-defined interface with the InP crystal 7. This is obtained as follows.

The embodiment of the method of the present invention has been clarified above, and according to this method, phosphine (P)l,) gas and ammonia (NH3) gas are reacted and the mixture is placed in the reaction tube 5. An insulating film 8 made of pentaphosphorous nitride (P, N5) is formed on the InP crystal. Assuming that the temperature on both sides of the reaction tube 5 is equal to or higher than the temperature at which phosphine (PH,) gas and ammonia (NH,) gas react to produce 5-hexaphosphorous nitride (P, N5), The temperature at the center of the reaction tube 5 is set to be at least 200°C lower than the temperature at both sides, and the InPnP2O5
Phosphine (PH,
) gas and ammonia (NH,) gas are reacted,
An insulating film 8 made of tcD, N5 is formed on the InP crystal 7, and for this purpose, the InP crystal 7 is made of 5-nitride 5-phosphorus (5-nitride, P, N5) is not heated to a high temperature higher than the temperature at which it is formed, and the partial pressure of the phosphorus (P) gas that makes up the InP crystal 7 is obtained, so the phosphorus that makes up the InPnP2O5 In this case, the temperature at the center of the reaction tube 5 is 200°C compared to that at both sides.
If the temperature is lower than that, the temperature of 200℃ is!
! As shown in Figure 2, phosphine (I PH,) gas and anthonia (re, ) gas react to form penta-S phosphorus nitride (P).
, N, ) is generated at approximately 850°C or higher, and if the temperature of IflP crystal 7 is approximately 500°C or higher, InPnP2O5! The surface is effectively thermally nitrided and further I
If nPnP2O5 degree is less than about 700℃, InPnP
If the phosphorus (P) that makes up 2O5 does not evaporate unnecessarily and the InPnP2O5 degree is below about 650°C, I! Five nitride pentaphosphorus (P,
In view of the fact that N5) is deposited, the lower limit of the temperature at which phosphine (PH,) gas and anthonia (NH,) gas react to produce pentaphosphorous nitride (P, N, ) is particularly important. At about 850°C, five phosphorus nitride (P, N
, ') is effectively deposited at approximately 650°C.
It was decided based on the difference between Furthermore, the temperature at the center of the reaction tube 5 is lower by 200°C or more than that at both sides, and from the point mentioned above in FIG. The temperature range from ℃ to 650℃ is defined as a town.

Furthermore, according to the method of the present invention described above, when the relationship between the film thickness (X) of the insulating film 8 and the time for forming the insulating film 8 was measured, as shown in FIG. 5, the film thickness linearly increased with time. The results showed that the change occurred by a relatively large amount of change.

The results shown in FIG. 5 were obtained when the temperatures at the center and both sides of the reaction tube 5 were 590° C. and 860° C., respectively. According to the method of the present invention described above, it is possible to easily form the insulation film 1 [8] as a tortoise having the desired thickness, and to form the insulation film 8 to a relatively thick thickness in a short period of time. It also has the feature that it can be formed in any shape.

Furthermore, according to the method of the present invention described above, the insulating film 8 can be formed as having the desired excellent interface characteristics between InPnP2O5, as described above. It was obtained as having a fine structure and excellent chemical resistance.Therefore, the insulating film 8 was made of InPnP2.
It has the desired excellent interfacial properties between O5 and is characterized by being able to be obtained as a high quality product. This can be confirmed by using the structure in which the insulating film 8 is formed on the InP crystal 7 by the method of the present invention, and the InPnP2O5 conductor S1
A 6Ml8 diode was prepared with the insulating film 8 as the insulator I, and the capacitance (PF) versus voltage (V) characteristics were measured using the frequency between the semiconductor S and the metal M as a parameter. , as shown in Figure 4, was obtained with almost no hysteresis characteristics, and the InPnP2O5 plane level density measured using the Terman method was 10.
This was also confirmed by the fact that an extremely small value of 15 g eV was obtained.

Incidentally, an MI8 diode similar to that described above was created, except that the insulating film 8 of the MIS diode described above was an insulating film formed by the conventional OVD method.
When similar capacitance vs. voltage characteristics were measured, the capacitance vs. voltage characteristics were obtained as shown in FIG. An extremely large value of eV was obtained.

In the above, phosphine (PH3) is used as the gas.
Pentaphosphorous nitride (P,N5) on InP crystal using gas
We have described the implementation of the present invention in the case of forming an insulating film made of
When forming an insulating film made of pentaarsenic nitride (As3N5) on a crystal made of Gas, InAs, etc. using a gas such as A/Sb%Garb, using a gas made of a hydride of sb as a source gas, In8b
It will be obvious that the same excellent effects as described above can be obtained by applying the present invention to the case where an insulating film made of sb nitride is formed on a crystal made of sb or the like.

4. Brief description of the drawings FIG. 1 is a route diagram for explaining the method of forming an insulating film on a compound semiconductor crystal according to the present invention, FIG. 2 is a temperature characteristic diagram for explaining the present invention in detail, and FIG. The figure shows the relationship between the thickness of the insulating film and the formation time of the insulating film, and FIG. Figure 5 shows M configured using the conventional method.
It is a ``# quantity vs. voltage characteristic diagram of an I8 diode.

In the figure, 1 is a nitrogen gas source, 2 is a hydrogen chloride gas source, 5 is a phosphine gas source, 4 is an ammonia gas source, 5 is a reaction tube, 6 is a heating source, 7 is an InP crystal, and 8 is an insulating film.

Applicant Nippon Telegraph and Telephone Public Corporation Figure 1 Figure 2 Figure 8 □Time Figure 5 Number -6-4-20246 -4LfL(V)- Public enterprise suspension procedure amendment document December 30, 1980 Patent Director-General Kazuo Wakasugi 1, Indication of the case 1981 Patent Application No. 151-464
No. 2, Title of the invention Insulating film on a compound semiconductor crystal and its formation method 3, Relationship with the amended person's case Patent applicant address 1-1-6 Uchisaiwai-cho, Chiyoda-ku, Tokyo 100 Name (422) Nippon Telegraph and Telephone Public Corporation Representative Tsune Shinfuji 4, Agent address Hidekazu Kioicho TBR 820 No. 6, 5-7 Kojimachi, Chiyoda-ku, Tokyo 102, Number of inventions increased by amendment 37, Subject of amendment Full text of specification 7. Contents of the amendments: Specification as attached (full text corrected) 1. Title of the invention Insulating film on compound semiconductor crystal and method for forming the same 2. Scope of claim 1. Formed on compound semiconductor crystal containing group V elements In the insulating film made of a nitride of a group V element, the insulating film is made of a nitride of a group V element produced by a reaction between a source gas containing a group V element and ammonia gas, and the compound semiconductor crystal is An insulating film on a compound semiconductor crystal, characterized in that it is a film deposited on top of the compound semiconductor crystal.

2. In an insulating film made of a nitride of a group V element formed on a compound semiconductor crystal containing a group V element, the insulating film is generated by a reaction between a source gas containing a group V element and ammonia gas. Nitride of group V element is V
A film formed by depositing a compound semiconductor crystal containing a group element while the compound semiconductor crystal is thermally nitrided by the reactive nitrogen gas generated by the above reaction.
An insulating film on a compound semiconductor crystal characterized by:

3. In a method for forming an insulating film on a compound semiconductor crystal in which an insulating film made of a nitride of a group V element is formed on a compound semiconductor crystal containing a group V element, the compound semiconductor crystal is placed in a reaction region, and the above reaction is performed. In the region, a source gas containing a group V element and the ammonia gas are reacted, and a nitride of a group V element generated by the reaction is deposited on the compound semiconductor crystal. 1. A method for forming an insulating film on a compound semiconductor crystal, the method comprising: forming an insulating film on a compound semiconductor crystal.

4. In a method for forming an insulating film on a compound semiconductor crystal in which an insulating film made of a nitride of a group I element is formed on a compound semiconductor crystal containing a group V element, the compound semiconductor crystal is The source gas containing the Group V element and the ammonia gas are arranged in the center of the reaction region having a low-temperature temperature distribution, and in the reaction region, the temperature on both sides of the reaction region is adjusted so that the source gas containing the group V element reacts with the ammonia gas. The temperature at the center is set to be higher than the temperature at which nitrides of group V elements are formed, and the temperature at the center is 2°O higher than the temperature at both sides.
The source gas containing the Group V element and the ammonia gas are reacted at a temperature lower than 10°C, and the nitride of the Group V element produced by the reaction is deposited on the compound semiconductor crystal. A method for forming an insulating film on a compound semiconductor crystal, comprising: forming an insulating film made of a nitride of a group V element.

3. Detailed Description of the Invention The present invention relates to an insulating film made of a nitride of a group I element formed on a compound semiconductor crystal containing a group V element, and a method for forming the same.

Conventionally, an insulating film made of a nitride of a group V element formed on a compound semiconductor crystal containing a group V element is a thermal nitride film formed by thermally nitriding the surface of a compound semiconductor crystal containing a group V element. Something is being proposed.

However, such an insulating film made of a thermal nitride film is formed on the surface of a compound semiconductor crystal containing a group I element while evaporating the group V element from the compound semiconductor crystal containing a group V element. be.

Therefore, the above-mentioned conventional insulating film made of a nitride of a group V element has the disadvantage that it does not have good interface characteristics with a compound semiconductor crystal containing a group V element, and is not of high quality. Ta.

In addition, as a method for forming an insulating film made of a nitride of a group V element on a compound semiconductor crystal containing a group V element, conventionally, the surface of a compound semiconductor crystal containing a group V element is heated in a heat chamber.
A method has been proposed in which an insulating film made of a nitride of a group V element is formed on a compound semiconductor crystal containing a group V element.

However, in the case of such a method, the speed at which the surface of a compound semiconductor crystal containing a group V element is thermally nitrided is extremely slow, so it is necessary to form an insulating film made of a nitride of a group V element to the required thickness. It has the disadvantage that it takes a long time to complete.

In addition, in the process of thermally nitriding the surface of a compound semiconductor crystal containing group V elements, group V elements evaporate to the outside from the compound semiconductor crystal containing group V elements, so that an insulating film made of a nitride of group V elements is formed. , and a compound semiconductor crystal containing a group V element, which has excellent interfacial properties and cannot be formed as a high-quality product.

Therefore, the present invention proposes a novel insulating film made of a nitride of a group V element, which is formed on a compound semiconductor crystal containing a group V element, and a method for forming the same, which is free from the above-mentioned drawbacks. The following will become clear from the description of embodiments of the method of forming an insulating film according to the present invention.

FIG. 1 shows an example of an apparatus used to form an insulating film by the method according to the invention.

In Figure 1, 1 is a nitrogen gas source from which pure nitrogen gas is obtained, 2 is a hydrogen chloride gas source from which hydrogen chloride gas is obtained, and 3
13) indicates a source gas source from which phosphine (P 2 ) gas is obtained as a source gas, and 4 indicates an ammonia gas source from which ammonia (NH 3 ) gas is obtained.

Further, 5 is a reaction tube made of quartz, and inside the reaction tube 5 is InP as a compound semiconductor crystal containing group V elements.
A crystal 7 is arranged.

Further, numeral 6 indicates a heat source disposed around the reaction tube 5 for heating the reaction tube 5.

The above is an example of an apparatus used for forming an insulating film by the method according to the present invention.

In an example of the method for forming an insulating film according to the present invention, first, nitrogen gas is introduced into the reaction tube 5 from the nitrogen gas source 1,
The inside of the reaction tube 5 is replaced with nitrogen gas.

Next, hydrogen chloride gas is supplied into the reaction tube 5 from the hydrogen chloride gas source 2, and 20% of the amount of hydrogen chloride gas is mixed into the nitrogen gas in the reaction tube 5.

Next, the reaction tube 5 is heated to about 200° C. by the heating source 6, thereby etching the surface of the tnp crystal 7 with hydrogen chloride gas, thereby cleaning the surface of the np crystal 7.

Next, nitrogen gas from the nitrogen gas source 1 is introduced into the reaction tube 5 to replace the inside of the reaction tube 5 with nitrogen gas, thereby removing hydrogen chloride gas from the inside of the reaction tube 5.

Next, phosphine (PH3) gas and ammonia (NH3) gas are respectively introduced into the reaction tube 5 from the source gas source 3 and the ammonia gas source 4 at a ratio of about 1=1.

In this case, the temperature distribution inside the reaction tube 5 is as shown in FIG. The temperature is 850°C or higher at which 5-triphosphorous nitride (P3NS) gas consisting of nitrides is generated, and the temperature in the center is 200°C or more lower than the temperature on both sides, for example, 59°C.
Each law distribution is set to 0°C.

Here, the temperature at the center of the reaction tube 5 is set to be more than 200°C lower than that at both sides.As shown in FIG.
The temperature at which gas and ammonia (NH3) gas react to produce 5-nitride 3 * (P, N,) is approximately 850°C.
The above is above, and if the temperature of the nP crystal 7 is about 500°C or higher, the surface of the InP crystal 7 is effectively thermally nitrided, and furthermore, if the humidity of the InP crystal 7 is about 100°C or lower, , from the InP crystal 7, the phosphorus (P) that constitutes it
Further, if the temperature of the TnP crystal 7 is about 6506 C or lower, triphosphorous nitride (P) is effectively formed on the In'P crystal 7.

Phosphine (P
H3> The lower limit temperature of about 850°C at which gas and ammonia (NH3) gas react to produce 5-triphosphorous nitride (PsN), and the effect of 5-triphosphorous nitride (PN) on the InP crystal 7. This was determined based on the difference between the upper limit temperature at which the film can be deposited and approximately 650°C.

Note that the temperature at the center of the reaction tube 5 is set to be at least 200°C lower than that at both sides, and the temperature at the center of the reaction tube 5 is about 500°C, as described above in FIG.
It is desirable that the temperature is in the range of .degree. C. to 650.degree.

In this case, phosphine (PH3) gas and ammonia (NH3) gas react in the high temperature regions on both sides of the reaction tube 5, and 5-triphosphorous nitride (P3N) gas is produced. In this case, in the high temperature region, excess phosphorus (P) is present in the reaction in this case.
gas and reactive nitrogen (N) gas are generated. And those, 5 triphosphorous nitride (P, Naru) gas, and 1!1 (P)
Because of the temperature gradient between the high-temperature regions on both sides of the reaction tube 5 and the low-temperature region in the center, all of the gas and reactive nitrogen (N) gas are concentrated in the central region where the InP crystal 7 is placed. Flows toward the low temperature region and stays there.

Therefore, the above-mentioned 5-triphosphorous nitride (PN) gas, 5 11i (P) gas, and reactive nitrogen (N) gas effectively exist on the InP crystal 7.

As a result, while the surface of the InP crystal 7 is thermally nitrided by the reactive nitrogen (N) gas, 5-triphosphorus nitride (P3N) is uniformly deposited on the InP crystal 7. Then, an insulating film 8 made of 5 nitride 3 vA is formed.

In this case, since there is a gas partial pressure of *(P) on the InP crystal 7, the phosphorus (P) constituting it does not evaporate unnecessarily from the InP crystal 7.

The embodiments of the insulating film and the method for forming the same according to the present invention have been clarified above.

The insulating film 8 according to the present invention described above contains a group V element (P) produced by a reaction between phosphine (PH) gas as a source gas containing a group V element (P) and ammonia (N + -13> gas). ) is a film formed by depositing 5 nitride 3 m (P3N,) on the InP crystal 7 having the group V element 1 (P), and the surface of the InP crystal 7 having the group V element (P). Therefore, the insulating film 8 according to the present invention described above is not a film formed by thermally nitriding the V group element (P) while evaporating the V group element (P) from the InP crystal 7 having the V group element (P) to the outside. It is not formed on the surface of an In P7 crystal containing a group element (P).

Therefore, the insulation 18 according to the present invention described above is composed of group V elements (
It has the characteristics of having good interfacial characteristics with the InP crystal 7 having P) and having high quality.

In addition, the insulation 111J8 according to the present invention described above uses phosphine (PH3
5 triphosphorous nitride (P3N,) containing group V element P produced by the reaction between ) gas and ammonia (N I-1,) gas
However, on the Inp crystal 7 containing the group V element (P), the I
The film is formed by depositing the nP crystal 7 while being nitrided by the reactive nitrogen gas generated by the reaction just described.

Therefore, the above-mentioned insulating film 8 according to the present invention is formed on the surface of the InP crystal 7 having the group V element (P) while evaporating the group V element (P) from the InP crystal 7 having the group V element (P). The InP crystal 7 having the group V element (P) was deposited on the InP crystal 7 while being thermally nitrided.

Therefore, the insulating film 8 according to the present invention described above has a group V element (
It has the characteristics of having good interfacial characteristics with the InP crystal 7 having P) and having high quality.

Furthermore, since the insulating film 8 according to the present invention described above (a) is formed as described above, it has a dense structure and excellent chemical resistance.

Therefore, the insulating film 8 according to the present invention described above has good interfacial characteristics with the InP crystal 7 containing the group V element (P), and is of high quality.

This means that the InP crystal 7 containing the group V elements mentioned above
Using the structure in which the insulating film according to the present invention is formed in the second part, an MIS diode is created in which the InP crystal 7 is the semiconductor S1 and the insulating film 8 is the insulator I, and the frequency between the semiconductor S and the metal M is The parameter capacity (PF) vs. voltage (
V) When the characteristics were measured, the capacitance vs. voltage characteristics were obtained with almost no hysteresis characteristics, as shown in Figure 4, and the InP characteristics were measured using the Terman method.
This was also confirmed because the surface state density of crystal 7 was obtained at an extremely small value of 10''/cm' eV.

Incidentally, in the MIS diode described above, except that the insulating film 8 is an insulating film formed by the conventional CVD method, a MIS diode similar to that described above was created, and similar capacitance vs. voltage characteristics were measured. As a result, the capacitance versus voltage characteristic was obtained as one exhibiting a remarkable hysteresis characteristic, as shown in FIG.
The surface unit of r1P crystal is 1Q +1 / cmleV
An extremely large value was obtained.

Further, the method for forming an insulating film according to the present invention described above uses phosphine (Pl) as a source gas containing a group V element (P).
-13) Gas and ammonia (NH3) gas are reacted, and the reaction produces 5-triphosphorous nitride (P3N,
) is deposited on the InP crystal 7 disposed in the reaction tube 5 to form an insulating film 8 made of pentaphosphorous nitride (PsN, ) on the InP crystal 7.

Therefore, according to the method for forming an insulating film according to the present invention described above, in the process of forming the insulating film 8 made of 5 triphosphorus nitride (P3N), g4 (P3N) is extracted from the lnP crystal 7 as a group V element.
) does not evaporate to the outside, so the insulating film 8 according to the present invention
As mentioned above, it has the characteristics that it has excellent interfacial properties with the TnP crystal 7 and can be formed as a high quality product.

Furthermore, the method for forming an insulating film according to the present invention described above is based on In
The P crystal 7 is placed in the center of the reaction tube 5, which has a law distribution in which the temperature at the center is lower than that at both sides. H3＞
Gas and ammonia (NH,) gas react to form 5 nitride 3
Phosphine (PH3) gas and ammonia (N H3 ) gas, and the 5-triphosphorus nitride (P3N, ) produced by the reaction is deposited on the InP crystal 7.
An insulating film 8 according to the present invention made of phosphorus (P, N,) is formed. For this reason, the InP crystal 7 is not heated at a high temperature higher than the temperature at which phosphine (PH3) gas and ammonia (NH,) gas react to produce 5-triphosphorous nitride (P,N-). A partial pressure of the phosphorus (P) gas constituting the InP crystal 7 is obtained on the InP crystal 7. Therefore, the phosphorus (P) constituting the InP crystal 7 unnecessarily evaporates. Never.

Therefore, according to the method for forming an insulating film according to the present invention described above, it is possible to form the insulating film 8 according to the present invention to have the desired excellent interface characteristics with the InP crystal 7 as described above. It has the characteristic that it can be done.

Further, according to the method for forming an insulating film according to the present invention described above,
Thickness (in) of insulating film 8 versus time for forming insulating film 8
As shown in FIG. 3, the relationship was measured, and the results showed that the film thickness changes linearly with time by a relatively large amount of change. The results shown in FIG. 3 indicate that the temperatures at the center and both sides of the reaction tube 5 were 590°C and 86°C, respectively.
This is the case at 0°C.

This result also shows that according to the method for forming an insulating film according to the present invention described above, the insulating film 8 according to the present invention can be easily formed to a desired thickness, and the insulating film 8 can be easily formed to have a desired thickness.
can be formed to a relatively large thickness in a short period of time.

Furthermore, according to the method for forming an insulating film according to the present invention described above, the insulating film 8 according to the present invention can be formed to have the desired excellent interface characteristics with the InP crystal 7, as described above. However, the insulating film 8 can be obtained having a fine structure and excellent chemical resistance.

Therefore, according to the method of forming an insulating film according to the present invention described above, the insulating film 8 according to the present invention has almost no hysteresis characteristic when viewed in terms of the capacitance versus voltage characteristics described above with reference to FIG. It has the characteristics that it has excellent interfacial characteristics with the InP crystal 7, and can be formed as a high-quality product.

Note that the insulating film made of nitride of group V elements is made of phosphine (
Source gas consisting of P H3) gas and ammonia (NH3) gas
3) An example has been described in which the film is formed by depositing phosphorus (P) nitride produced by reaction with gas on InP crystal 7.

However, an insulating film made of group V element nitride is coated with a source gas of arsine (AsH3) gas and ammonia (
Arsenic (As) produced by reaction with NH3) gas
The nitride (5 triarsenic nitride (As3N, )) or antimony (Sb)' hydrogen nitride is InP crystal 7 or other GaASl 1nAS
It is obvious that the film can also be formed by depositing on a compound semiconductor crystal containing a group V element such as.

Note that it is clear that even in such a case, the above-described features of the insulating film according to the present invention can be obtained.

In addition, in the above, phosphine (
An example of how to form the insulating film 8 made of pentaphosphorous nitride (P3N, ) according to the present invention on the lnp crystal γ using the P H3> gas has been described.

However, arsine (Asl-4
3) Using gas, I n'P crystal or GaAs,
When forming an insulating film made of triarsenic nitride (As, N,) on a compound semiconductor crystal containing group V elements such as InAS, a gas made of antimony (Sb) hydride is used as the source gas. InP crystal or At
Sb, GaSb.

It is obvious that an insulating film made of antimony (Sb) nitride can also be formed on a compound semiconductor crystal containing a group V element such as InSb.

It is clear that even in such a case, it is possible to obtain the same excellent characteristics as the above-described method of forming an insulating film according to the present invention.

4. Brief Description of the Drawings FIG. 1 is a route diagram for explaining an embodiment of a method of forming an insulating film made of a nitride of a group V element on a compound semiconductor crystal according to the present invention.

FIG. 2 is a temperature characteristic diagram for explaining an embodiment of the method for forming an insulating film according to the present invention.

FIG. 3 is a diagram showing the relationship between the thickness of the insulating film and time when forming the insulating film by the method according to the present invention.

FIG. 4 is a capacitance versus voltage characteristic diagram of a MIS diode constructed using the insulating film and the method for forming the same according to the present invention.

FIG. 5 is a capacitance versus voltage characteristic diagram of a MIS diode constructed using a conventional insulating film and its formation method.

1・・・・・・・・・・・・Nitrogen gas source 2・・・・・・
...Hydrogen chloride gas source 3...
・Bosphin gas source 4・・・・・・・・・Ammonia gas source 5・・・・・・・・・Reaction tube 6・・・・・・・・・Heating Source 7...InP crystal 8...
...Insulating film applicant Nippon Telegraph and Telephone Public Corporation

Claims (1)

[Claims] In the reaction region, a north gas containing a group V element is reacted with ammonia gas, and the group V element is nitrided on the compound semiconductor crystal containing the group V element arranged in the reaction region. In the method of forming an insulating film on a compound semiconductor crystal, which forms an insulating film made of a material, the temperature distribution in the reaction region is made into a valley-shaped distribution where the center part is higher than the both sides. The temperature of both sides is set to a temperature higher than the temperature at which the north gas containing the group V element reacts with the ammonia gas to form a nitride of the group V element. The temperature of the central portion is set to be at least 20Q°C lower than the temperature of both sides, and the north gas containing the Group V element and the ammonia gas are allowed to react with each other while the compound semiconductor crystal is placed in the central portion. Features: A method for forming an insulating film on a conductor crystal in a compound.