JPH09223673A - Destaticizing method of semiconductor substrate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide destaticizing method which enables sufficient destaticizing process with a semiconductor substrate while simplifying manufacture process of a semiconductor element. SOLUTION: When making a specified semiconductor layer crystal-grow on a semiconductor substrate 12, firstly, the inside of a substrate holding part 32 of a carrier device 28 for carrying the semiconductor substrate 12 to a reaction furnace 26 without taking it out of a system is made specified gas atmosphere (H2 -N2 atmosphere). Then, by generating the ion of the H2 -N2 gas in the substrate holding part 32, the semiconductor substrate 12 placed in the substrate holding part 32 is destaticized. By this, the semiconductor substrate 12 is destaticized. Therefor, prior to crystal grows, destaticized can be done without separately providing with destaticizing process in a destaticizing device, further, the destaticized semiconductor substrate 12 is, instead of taken outside, carried to the reaction furnace 26, so that sufficient destaticizing treatment is performed with the semiconductor substrate 12 while simplifying the manufacture process of a semiconductor element.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a neutralizing method for neutralizing a semiconductor substrate when a semiconductor layer is crystal-grown on the semiconductor substrate to manufacture a semiconductor device.

[0002]

2. Description of the Related Art For example, in a semiconductor device such as a light emitting diode or a semiconductor laser, a semiconductor layer such as GaAs or AlGaAs is formed on a semiconductor substrate such as GaAs (gallium arsenide) or Si (silicon) by MOCVD (Metal Organic Chemical Vapor Depositio).
n: metal organic chemical vapor deposition) method or LPE (Liquid Phase)
Epitaxy: liquid phase epitaxy) and the like, and is manufactured by laminating crystals and stacking them.

The semiconductor substrate used for the above-described crystal growth is, for example, a cylindrical ingot obtained by a pulling method such as the CZ method is cut into a predetermined thickness by a diamond cutter or the like, and further, a predetermined surface roughness is obtained. It is manufactured by polishing so as to obtain the sheath flatness. And
The semiconductor substrate is transported from the semiconductor substrate manufacturer to the semiconductor element manufacturer in a state of being hermetically sealed in a disc-shaped plastic carrier 10 whose sectional shape is shown in FIG. In the figure, the carrier 10 includes a body 16 having a recess 14 for supporting the semiconductor substrate 12 at its peripheral portion, and a recess 18 having a similar shape to the body 1.
6 and a lid 20 for forming an enclosed space between the lid 20 and the main body 16, and the semiconductor substrate 12 is formed on the inner surface of the lid 20 in which the recess 18 is formed. A plastic spring 22 for pressing and fixing the body 16 is provided.

[0004]

By the way, when crystal-growing a semiconductor layer on the semiconductor substrate 12 as described above, if the semiconductor substrate 12 is charged, the inside or inside of the reaction furnace for crystal-growing the crystal. Since the dust existing in the transport device for transporting the semiconductor substrate 12 therein is adsorbed on the surface thereof, the number of pits increases and a defect of the semiconductor element occurs. Therefore, when crystal-growing a semiconductor layer on the semiconductor substrate 12 to manufacture a semiconductor element, it is necessary to eliminate the charge on the semiconductor substrate 12.

Conventionally, prior to crystal growth, a semiconductor element manufacturer has performed an etching process for the purpose of removing strains, oxide films, etc. generated during polishing in the semiconductor substrate 12. The semiconductor substrate 12 was discharged. However, in recent years, for the purpose of simplifying the manufacturing process and the like, crystal growth is performed without etching treatment by a semiconductor device manufacturer, so that the carrier 10 is subjected to the etching treatment after the semiconductor substrate manufacturer. The semiconductor substrate 12 is transported while being hermetically sealed.

The carrier 10 conveys the semiconductor substrate 12 while being pressed and fixed by the spring 22 as described above. However, if the semiconductor substrate 12 is vibrated subtly by the vibration applied during the conveyance. , Recess 1
4 and the spring 22 cause the semiconductor substrate 1 to slide.
2 will be charged. Therefore, there is a problem in that a semiconductor device manufacturer needs to perform static elimination treatment before crystal growth, and the manufacturing process cannot be sufficiently simplified even though the etching treatment is omitted.

Moreover, since the above-mentioned static elimination processing is carried out in a static elimination apparatus provided separately from the reaction furnace, the semiconductor substrate 12 is not removed during handling such as when transferring the static elimination apparatus into the reaction furnace. There is also a problem that charging may occur again, and the state of static elimination treatment before crystal growth is not always sufficient.

The present invention has been made in view of the above circumstances, and it is an object of the present invention to make it possible to perform sufficient static elimination processing on a semiconductor substrate while simplifying the manufacturing process of a semiconductor element. The purpose is to provide a method of eliminating static electricity.

[0009]

In order to achieve such an object, the gist of the present invention is to remove the electric charge from the semiconductor substrate when crystal-growing the semiconductor layer on the semiconductor substrate in a reaction furnace. The static elimination method of
(a) an atmosphere step in which the inside of a transfer device for transferring the semiconductor substrate placed inside the reaction furnace continuously to the reaction furnace without taking out the semiconductor substrate into a predetermined gas atmosphere , (B) a static elimination step of eliminating static electricity from the semiconductor substrate placed in the transport device by generating ions of the predetermined gas in the transport device.

[0010]

According to this structure, an atmosphere process in which the inside of the transfer device for transferring the semiconductor substrate to the reaction furnace without taking the semiconductor substrate out of the system is set to a predetermined gas atmosphere, and the ions of the gas are transferred in the transfer device. A static elimination step of static eliminating the semiconductor substrate placed in the transfer device by generating
The semiconductor substrate is neutralized by the process including. for that reason,
Even when the semiconductor layer is crystal-grown without etching the semiconductor substrate, the static elimination can be performed without separately providing a step of static elimination inside the static eliminator prior to the crystal growth. Is transported to the reactor without being taken out,
It is possible to perform sufficient static elimination processing on the semiconductor substrate while simplifying the manufacturing process of the semiconductor element. The gas ions may be generated in the carrier device or may be sent from an ion generator connected to the carrier device.

[0011]

Another aspect of the present invention is preferably such that the static eliminating step includes an ion generating step of generating ions of the predetermined gas by irradiating the gas in the carrier with ultraviolet rays. By doing so, the gas ions for eliminating the charge on the semiconductor substrate will be generated by the irradiation of ultraviolet rays, so that there is a flammable gas in the carrier device as compared with the case of generating ions by discharge. In this case, the static electricity can be safely removed without causing an explosion or the like.

As a method of irradiating the gas in the transfer device with ultraviolet rays, in addition to a method of providing an ultraviolet ray generating device inside the conveying device to directly generate ultraviolet rays inside the conveying device, an ultraviolet ray generating device is externally provided and transferred. The device may be made of an ultraviolet-transparent material and may be irradiated with ultraviolet light from the outside.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIG. 2 is a diagram schematically showing the structure of a crystal growth apparatus 24 to which the method for static elimination of a semiconductor substrate according to an embodiment of the present invention is applied. In the figure, a crystal growth apparatus 24 is used for the semiconductor substrate 1 by a vapor phase growth method such as a MOCVD method.
2 is used for crystal growth of a predetermined semiconductor layer on the substrate 2. A reaction furnace 26 into which a predetermined source gas is introduced from a source gas supply facility (not shown) through a pipe (not shown) and a plurality of semiconductor substrates 12 are held. A transport device 28 for sequentially transporting the substrates one by one into the reaction furnace 26 and an ultraviolet ray generation device 30 for irradiating the transport device 28 with ultraviolet rays are provided.

The transfer device 28 is made of a material that transmits ultraviolet rays, such as quartz glass.
6, a cylindrical substrate holder 32 for holding a plurality of semiconductor substrates 12 inside, and the substrate holder 32 and the reaction furnace 26 are connected to each other. It comprises a loading / unloading section 34 for loading or unloading the semiconductor substrate 12 from the holding section 32 into the reaction furnace 26.

The above-mentioned substrate holder 32 is used for the semiconductor substrate 12
A wafer tray carrier 38 is provided which holds the wafer trays 36 respectively mounted thereon in the vertical direction at a predetermined interval and is movable in the vertical direction as a whole. The wafer tray 36 is made of an insulating material such as carbon coated with SiO ₂ or SiC. The semiconductor substrate 12 is always placed on the wafer tray 36 in the crystal growth apparatus 24, so that the insulating property in the apparatus is ensured. In the figure, reference numeral 40 is a loading / unloading opening that is opened to load or unload the semiconductor substrate 12 into the crystal growth apparatus 24 and closed to hermetically seal the substrate holding portion 32, and 39 is an internal portion. Is a vacuum pump that discharges the internal air in order to create a predetermined gas atmosphere, and 41 is a gas introduction device that introduces a predetermined gas into the interior.

The loading / unloading section 34 is provided with a tray loading / unloading mechanism 44 for sequentially removing the wafer trays 36 from the wafer tray carrier 38 of the substrate holding section 32 and loading / unloading the wafer tray 36 into / from the reaction furnace 26 through the loading / unloading path 42. It was
Gate valves 46a and 46b are provided at the connecting portion with the substrate holding portion 32 and the connecting portion with the reaction furnace 26, respectively. The gate valves 46a and 46b are for hermetically closing the space between the substrate holding portion 32 and the reaction furnace 26, respectively.

A susceptor 48, which can be moved in the vertical direction in the drawing and is driven to rotate about a vertical center line, is provided in the reaction furnace 26.
The semiconductor substrate 12 carried from the substrate holding section 32 is held on the tray 8 by the tray loading / unloading mechanism 44. The reaction furnace 26 is provided with a heating device (not shown) for heating the susceptor 48 to a predetermined temperature by, for example, an induction coil or a heater, and the semiconductor substrate 12 held on the susceptor 48 is indirectly or It is designed to be heated directly.

The crystal growth apparatus 24 configured as described above
A method of crystal-growing a predetermined semiconductor layer on the semiconductor substrate 12 will be described below with reference to the process chart of FIG. Note that steps 2 to 8 of the following steps are automatically performed by being controlled by a control device (not shown).

First, in the loading step of step 1, the plurality of wafer trays 36 on which the semiconductor substrates 12 are placed are placed on the wafer tray carrier 38 in the substrate holding section 32 from the loading / unloading port 40. Then, after closing the loading / unloading port 40 to seal the inside of the substrate holding part 32, a predetermined starting operation is performed, whereby the following respective steps are executed. That is,
In the exhausting step of step 2, the vacuum pump 39 is operated to discharge the internal air, and in the gas introducing step of the following step 3, the gas introducing device 41 is operated to cause, for example, H ₂ in the substrate holding part 32. And N ₂ gas is introduced. In this embodiment, this step 3 corresponds to the atmosphere step.

As described above, the inside of the substrate holder 32 is H ₂ -N
After the atmosphere is set to ₂ atmospheres, in the ultraviolet irradiation step of step 4, the substrate holding portion 32 is irradiated with ultraviolet rays. At this time,
As described above, since the substrate holding portion 32 is made of an ultraviolet-transparent material, the gas (H ₂ —N ₂ ) introduced inside is ionized by the ultraviolet rays emitted from the outside. As a result, the semiconductor substrate 12 placed in the substrate holding part 32 is discharged. Therefore, in this embodiment, this step 4 corresponds to the ultraviolet ray generation step and the static elimination step.

In the carrying-in step of the following step 5, the gate valve 46a between the substrate holding section 32 and the carrying-in / carrying-out section 34 is opened, and the tray carrying-in / carrying-out mechanism 44 is operated, so that the wafer tray carrier 38 is loaded. One of the placed wafer trays 36 is removed from the wafer tray carrier 38 and conveyed to the reaction furnace 26 through the loading / unloading path 42, and the gate valve 46a is closed while the wafer tray carrier 38 is connected to the reaction furnace 26. Gate valve 46
b is opened, and the wafer tray 36 is placed on the susceptor 48 which is lowered to the lowermost portion.

Then, after the susceptor 48 is raised to a predetermined position, in a heating step of step 6, it is heated to a predetermined temperature for crystal growth by a heating device (not shown), and after reaching the predetermined temperature, the step is performed. In the gas introduction step of 7, the raw material gas supply equipment (not shown) supplies one to several kinds of predetermined raw material gas into the reaction furnace 26, so that one to several desired semiconductor layers are crystal-grown. After the crystal growth is completed in this way, when the susceptor 48 is lowered to the lowermost portion and the gate valve 46b is opened in the carry-out process of the process 9, the tray carry-in / carry-out mechanism 44 is operated again, whereby the susceptor 48 is operated. The wafer tray 36 on 48 is returned into the substrate holder 32. The detailed control method for crystal growth is not necessary for understanding the present invention, and thus the description thereof is omitted.

Then, returning to step 5, the semiconductor substrate 12
The other wafer trays 36 on which are mounted are repeatedly removed from the wafer tray carrier 38 and similarly processed in Steps 6 to 8 so that all the semiconductor substrates 12 put in the substrate holding unit 32 are predetermined. After crystal growth of the semiconductor layer of No.
A series of crystal growth steps are completed by opening the outlet 40 and taking out the wafer tray 36 (semiconductor substrate 12) from the inside of the substrate holder 32.

Here, in this embodiment, when crystallizing a predetermined semiconductor layer on the semiconductor substrate 12, the substrate of the transfer device 28 for transferring the semiconductor substrate 12 to the reaction furnace 26 without taking it out of the system. The atmosphere process of step 3 in which the inside of the holding portion 32 is set to a predetermined gas atmosphere (H ₂ -N ₂ atmosphere), and the substrate holding portion 32 holds the substrate by generating ions of the H ₂ -N ₂ gas. The semiconductor substrate 12 is destaticized by the steps including the destaticization step of Step 4 of destaticizing the semiconductor substrate 12 placed in the portion 32.
Therefore, even when the semiconductor layer is crystal-grown without etching the semiconductor substrate 12, the charge-eliminating process can be performed without separately providing a step of charge-eliminating process in the charge-eliminating device prior to the crystal growth, and the charge-eliminating process is performed. Further, the semiconductor substrate 12 is conveyed to the reaction furnace 26 without being taken out to the outside, so that the semiconductor substrate 12 can be sufficiently neutralized while simplifying the manufacturing process of the semiconductor element.

Further, in the present embodiment, in the static elimination step of the step 4, the gas (H ₂ -N ₂₎ in the substrate holding portion 32 is used.
Gas) is irradiated with ultraviolet rays to generate ions of the predetermined gas. By doing so, the gas ions for removing the electric charge from the semiconductor substrate 12 are generated by the irradiation of ultraviolet rays. Therefore, as compared with the case where the ions are generated by the discharge, the substrate holding unit as in the present embodiment. Even when a combustible gas such as H ₂ is present in 32, explosion or the like does not occur, the charge removal process can be safely performed, and the contamination of the semiconductor substrate 12 due to the spatter accompanying discharge is suppressed. It

Although one embodiment of the present invention has been described in detail with reference to the drawings, the present invention can be implemented in still another mode.

For example, in the above-described embodiment, ultraviolet rays are radiated into the substrate holder 32 from the ultraviolet ray generator 30 provided outside. However, for example, the ultraviolet ray generator 30 is provided in the substrate holder 32. There is no problem even if ultraviolet rays are generated internally.

Further, in the embodiment, the substrate holding portion 32
Gas ions were generated by irradiating the gas (H ₂ —N ₂ ) introduced into the interior with ultraviolet rays.
An ion generator may be connected to the substrate holder 32 and the gas ions generated by the ion generator may be introduced into the substrate holder 32 by a pump or the like.

In the embodiment, the charge is removed in the substrate holding part 32 of the transfer device 28. However, the charge is removed in the carry-in / out part 34 by irradiating the carry-in / out part 34 with ultraviolet rays. It does not matter if it is configured as.

Although not illustrated one by one, the present invention can be variously modified without departing from the spirit thereof.

[Brief description of drawings]

FIG. 1 is a diagram showing a cross-sectional structure of a carrier used for carrying a semiconductor substrate.

FIG. 2 is a diagram schematically showing a crystal growth apparatus to which a charge eliminating method according to an embodiment of the present invention is applied.

3A and 3B are process diagrams illustrating a process of performing static elimination and crystal growth by the crystal growth apparatus of FIG.

[Explanation of symbols]

 12: Semiconductor substrate 24: Crystal growth device 26: Reaction furnace 28: Transfer device 30: Ultraviolet generator

Claims (2)

[Claims] 1. A method of destaticizing a semiconductor substrate, which comprises destaticizing a semiconductor layer when crystal-growing a semiconductor layer on the semiconductor substrate in a reaction furnace, the method being provided continuously to the reaction furnace and mounted inside the reaction furnace. An atmosphere step of setting a predetermined gas atmosphere in a transfer device for transferring the semiconductor substrate into the reaction furnace without taking it out to the outside, and generating ions of the predetermined gas in the transfer device. And a static elimination step of static-eliminating the semiconductor substrate placed in the transfer device. 2. The static elimination method for a semiconductor substrate according to claim 1, wherein the static elimination step includes an ion generation step of generating ions of the predetermined gas by irradiating the gas in the transfer device with ultraviolet rays.