JPH088213B2 - Method for manufacturing compound semiconductor - Google Patents

Description

The present invention relates to a compound semiconductor containing mercury, such as CdxHg.
( _1- x) Te (hereinafter referred to as CMT), ZnxHg ( _1- x) Te (hereinafter referred to as ZMT), and other vapor phase growth methods (where Cd is cadmium, Hg is mercury, Te is Tellurium, Zn is zinc, x
Indicates a number satisfying 0 <x <1).

[Conventional technology]

Recently, research has been conducted on manufacturing the CMT and the like by a metal organic chemical vapor deposition method (MOCVD method).

The conventional technique will be described below with reference to the cross-sectional view of the conventional MOCVD apparatus for CMT production shown in FIG. 3. The reaction tube 1 for performing vapor phase growth has a gas introduction part 1a at one end and a gas discharge part 1b at the other end.
And a mass flow controller 2 in the gas introduction part 1a.
The pipe 3 is continuously connected via. Substrate 4 in reaction tube 1
A susceptor 5 made of carbon used for holding and heating is provided, and a mercury reservoir 6 for accommodating liquid mercury is arranged on the upstream side thereof. A heater 7 and an RF coil 8 are provided outside the reaction tube 1 so as to surround the reaction tube 1.

 Next, the operating method will be described in the case of manufacturing CMT.

In addition to mercury, dimethylcadmium (DMCd) for Cd and diethyl tellurium (DETe) for Te are used in the production of CMT. These DMCd and DETe are organic metals in a liquid state, for example, hydrogen is used as a carrier gas to be accompanied by bubbling, respectively, and then merged to be a vapor growth gas, which is precisely controlled to a predetermined flow rate by a mass flow controller 2 and is reacted through a tube 3. It is introduced into the tube 1.

The liquid mercury in the reaction tube 1 is heated to 180 ° C. to 250 by the heater 7.
Mercury vapor is generated by being kept at a predetermined temperature of ° C, and the susceptor 5 is heated at high frequency by the RF coil 8 to keep the substrate 4 on the susceptor 5 at about 400 ° C.

Under such a condition, the vapor growth gas introduced into the reaction tube 1 from the vapor growth gas introduction section 1a reaches the substrate 4 along with the mercury vapor on the mercury reservoir 6, and the DMCd, DETe undergoes thermal decomposition and reaction products are deposited on the substrate, and mercury vapor is deposited on the substrate according to the partial pressure in the vapor phase growth gas, forming a thin film to form a compound semiconductor containing mercury. Manufactured.

Further, as another conventional technique, a carrier gas such as hydrogen in the tube 3 is flown, and mercury vapor in the reaction tube 1 is entrained by the carrier gas, and a vapor phase growth gas of an organic metal is separately supplied in the reaction tube 1. There is also a method of producing a compound semiconductor similar to the above by introducing the same into the substrate 4, mixing them on the upstream side of the substrate 4 and supplying the mixture to the substrate 4.

[Problems to be Solved by the Invention]

However, the above-mentioned conventional technique has a problem when it is desired to change the composition ratio of mercury in the thin film. For example, when mercury vapor is entrained in the vapor phase growth gas, the composition ratio of mercury may be changed by changing the partial pressure of the mercury vapor in the basic phase growth gas supplied to the substrate 4. It can be changed rapidly by adjusting the flow rate of the growth gas, and thus the flow rate, but the change in flow rate hinders uniform growth of the thin film. Therefore, in order to control the partial pressure of mercury vapor while keeping the flow velocity of the vapor growth gas constant, in consideration of the uniformity of the thin film, the heating amount of the liquid mercury in the mercury reservoir 6 must be increased or decreased. However, the method of adjusting the heating amount has a disadvantage that quick and precise control cannot be performed. This is also an inconvenience that occurs when the partial pressure of mercury vapor supplied to the substrate is measured and the amount of mercury vapor is increased or decreased to keep the partial pressure constant.

Therefore, a method of arranging a mercury reservoir outside the reaction tube and supplying mercury vapor into the reaction tube through the tube can be considered. However, in this method, the mercury vapor is prevented from adhering to the inner surface of the tube. It has to be heated and maintained at a temperature equal to or higher than that of the mercury pool, which is not economical because the device manufacturing cost and heating cost increase. On the other hand, if the mercury reservoir is arranged in the reaction tube, not only the above-mentioned economical inconvenience does not occur, but also the inside of the reaction tube during vapor phase growth is higher than room temperature, so the heating amount for generating mercury vapor can be small. From this point of view, it is not preferable to provide the mercury reservoir outside the reaction tube.

The present invention has been made in view of the above points, and a mercury vapor generating section is provided in a reaction tube, and the partial pressure of mercury vapor generated in the mercury vapor generating section and supplied to the substrate is controlled so that the mercury vapor is uniformly distributed on the substrate. The present invention provides a method for producing a compound semiconductor, which rapidly forms a thin film.

[Means for solving the problem]

In the method according to claim 1 of the present invention, the mercury vapor generated in the reaction tube is supplied together with the vapor phase growth gas of the organic metal onto the substrate, and the organic vapor is generated together with the mercury vapor by utilizing the thermal decomposition reaction. In a method for producing a compound semiconductor, in which a reaction product of a metal is deposited on a substrate to form a thin film, the inside of the reaction tube near the mercury vapor generating part is partitioned along the gas flow direction to form at least two flow paths. , Among the divided flow paths,
Generate mercury vapor in at least one channel,
Introducing a vapor growth gas into each flow path, adjusting the gas flow rate of the remaining flow path according to the increase or decrease of the gas flow rate of the flow path for generating the mercury vapor, of the vapor growth gas to be introduced into the reaction tube It is characterized in that the partial pressure of mercury vapor supplied to the substrate is controlled while keeping the total amount constant.

Further, in the method according to claim 2, after the mercury vapor generated in the reaction tube is entrained in the carrier gas, it is mixed with the vapor phase growth gas of the organic metal and supplied onto the substrate to utilize the thermal decomposition reaction. In the method for producing a compound semiconductor in which a reaction product of an organic metal is deposited on a substrate together with the mercury vapor to form a thin film, at least the reaction tube in the vicinity of the mercury vapor generating section is partitioned along the gas flow direction. A flow path that forms two flow paths and that generates mercury vapor in at least one flow path of the divided flow paths and that introduces a carrier gas into each flow path to generate the mercury vapor. The gas flow rate of the remaining channels is adjusted according to the increase or decrease of the gas flow rate, and the partial pressure of mercury vapor supplied to the substrate is controlled while keeping the total amount of carrier gas introduced into the reaction tube constant. To do.

[Embodiment] First, one embodiment of the method according to claim 1 of the present invention will be described with reference to FIG. FIG. 1 is a sectional view of an apparatus for carrying out the present method, in which the same components as those in FIG. 3 are designated by the same reference numerals.

In the figure, in the vicinity of the mercury reservoir 6 which is a mercury vapor generating portion in the reaction tube 1, parallel partitions 11a and 11b are formed along the gas flow direction by a partition plate 10 to form parallel channels 11a and 11b.
A mercury reservoir 6 which is heated to a predetermined temperature by a heater 7 is arranged in 1b. The pipe 3 is branched on the downstream side of the mass flow controller 2, and the flow path 1 is provided via the flow control valves 12a and 12b, respectively.
It communicates with 1a and 11b respectively. The flow paths 11a and 11b do not need to be airtightly partitioned, and may be partitioned so that the vapor growth gas flows through each of them.

In the above structure, the vapor growth gas is set to a predetermined flow rate by the mass flow controller 2, and then the flow rate control valve 12
a, 12b are respectively introduced into the parallel flow paths 11a, 11b, the vapor growth gas flowing through the lower flow path 11b is accompanied by mercury vapor,
Others flow through the upper flow path 11a as they are, are mixed at the end of the partition plate 10, and are supplied to the substrate 4 on the susceptor 5 which is heated by the RF coil 8 at high frequency. Semiconductors are manufactured. When the distance between the edge of the partition plate 10 and the substrate 4 is short, it is desirable to provide a gas mixing means at the edge.

In this embodiment, for example, in order to increase the composition ratio of mercury in the thin film, the flow rate control valves 12a and 12b are controlled while the flow rate in the mass flow controller 2 is kept constant to increase the flow rate on the flow path 11b side. As a result, the flow velocity on the flow path 11b side increases, the amount of mercury generated increases, and the amount of mercury vapor supplied to the substrate 4 increases. On the other hand, the mass flow controller 2
Since the total amount of vapor growth gas is constant,
The flow rate of the other flow path 11a decreases as the flow rate increases on the 11b side. Therefore, it is possible to increase the amount of mercury vapor supplied to the substrate 4 while keeping the total amount of vapor phase growth gas introduced into the reaction tube 1 constant, thereby increasing the partial pressure of mercury vapor. Moreover, since the flow rate of the vapor growth gas introduced into the reaction tube 1 is constant, the flow velocity is also constant, and the uniformity of growth conditions can be maintained. Further, since the change of the mercury vapor amount is performed by controlling the flow rate of the vapor growth gas, it can be carried out quickly.

Next, one embodiment of the method according to claim 2 will be described with reference to FIG. FIG. 2 is a sectional view of an apparatus for carrying out the method,
In the figure, the same components as those in FIG. 1 are designated by the same reference numerals.

2 is different from FIG. 1 in that the gas flowing in the tube 3 is a carrier gas, and the vapor phase growth gas of an organic metal is introduced into the reaction tube 1 through the mass flow controller 20 and the tube 21 separately. That is, the vapor growth gas is mixed with the carrier gas accompanied by mercury vapor on the upstream side of the substrate 4.

In FIG. 2, the total amount of vapor phase growth gas introduced into the reaction tube 1 via the pipe 21 and the total amount of carrier gas introduced into the reaction pipe 1 via the pipe 3 are respectively the mass flow controllers 20 and 2. Held constant by. The amount of mercury vapor entrained in the carrier gas is controlled by adjusting the flow rate of the carrier gas flowing in the parallel flow paths 11a and 11b, and the amount of mercury vapor is kept constant while keeping the total amount of gas introduced into the reaction tube 1 constant. The pressure can be controlled.

In the above description, the case of horizontal vapor phase growth in which the vapor phase growth gas is flowed horizontally on the substrate surface is explained, but it is also applicable to the case of vertical type in which the vapor phase growth gas is flowed vertically to the substrate surface, In the case of the vertical type, the inside of the reaction tube in the vicinity of the mercury vapor generating part may be partitioned in the left-right vertical direction and configured according to both the above-mentioned examples. Further, the reaction tube can be divided into three or more flow passages, and at least one of the flow passages can be provided with a mercury vapor generating portion, and the same operation can be performed, and it is not necessary to form each flow passage in parallel. Instead, it can be implemented in an appropriate shape.

〔The invention's effect〕

As described above, the present invention controls the partial pressure of mercury vapor supplied to the substrate while the mercury vapor generating section is provided in the reaction tube. At least two flow paths are formed by partitioning along them, and mercury vapor is generated in at least one of the flow paths, and vapor phase growth gas or carrier gas is introduced into each flow path and introduced into the reaction tube. The vapor pressure growth gas or the carrier gas is kept constant and the flow rate of the gas flowing through each flow path is controlled to control the partial pressure of the mercury vapor. The partial pressure of mercury vapor in the gas can be controlled while the flow rate is kept constant and uniform vapor phase growth conditions are maintained, and the composition ratio of mercury in the thin film can be easily adjusted.

Further, according to the present invention, since the partial pressure of the mercury vapor is adjusted by adjusting the flow rate of the vapor growth gas or the carrier gas introduced into the flow path, the heating speed of the mercury reservoir can be adjusted more quickly than the case of adjusting the heating amount. Moreover, precise control is possible, and the effect of implementation is extremely large.

[Brief description of drawings]

FIG. 1 is a sectional view of an apparatus for explaining an embodiment of the method of the present invention, FIG. 2 is a sectional view of an apparatus for explaining another embodiment, and FIG. 3 is an apparatus for explaining a conventional vapor phase growth method. FIG. 1 ... Reaction tube, 1a ... Gas inlet, 1b ... Gas outlet,
2,20 …… Mass flow controller, 3,21 …… Tube, 4 ……
Substrate, 5 ... Susceptor, 6 ... Mercury reservoir, 7 ... Heater,
8 ... RF coil, 10 ... Partition plate, 11a, 11b ... Flow path, 12
a, 12b ... Flow control valve

Claims (2)

[Claims] 1. A mercury vapor generated in a reaction tube is supplied along with an organic metal vapor-phase growth gas onto a substrate, and a reaction product of the organic metal is produced together with the mercury vapor by utilizing a thermal decomposition reaction. In the method for producing a compound semiconductor, wherein a thin film is formed by depositing the same on a reaction tube in the vicinity of the mercury vapor generation section along the gas flow direction to form at least two flow paths, and the divided flow paths are defined. Among these, mercury vapor is generated in at least one flow passage, and a vapor growth gas is introduced into each flow passage, and the remaining flow passages are changed according to the increase or decrease in the gas flow rate of the flow passage for generating the mercury vapor. A method for producing a compound semiconductor, comprising adjusting a gas flow rate and controlling a partial pressure of mercury vapor supplied to a substrate while keeping a total amount of vapor phase growth gas introduced into a reaction tube constant. 2. A mercury vapor generated in a reaction tube is entrained in a carrier gas, mixed with a vapor phase growth gas of an organic metal and supplied onto a substrate, and a thermal decomposition reaction is used to combine with the mercury vapor. In a method for producing a compound semiconductor in which a reaction product of an organic metal is deposited on a substrate to form a thin film, at least two flow paths are formed by partitioning a reaction tube near the mercury vapor generation section along a gas flow direction. The mercury vapor is generated in at least one of the divided flow passages, and a carrier gas is introduced into each flow passage to increase or decrease the gas flow rate of the flow passage for generating the mercury vapor. A method for producing a compound semiconductor, characterized in that the partial gas pressure of mercury vapor supplied to the substrate is controlled while the total amount of carrier gas introduced into the reaction tube is kept constant by adjusting the gas flow rate of the remaining flow channels according to the method. .