JPH0717997B2 - Plasma oxidation or nitriding method and apparatus used therefor - Google Patents

Description

Description: TECHNICAL FIELD The present invention oxidizes or nitrides the surface of a sample made of a semiconductor or a metal by irradiating plasma of oxygen or a gas containing oxygen, or nitrogen or a gas containing nitrogen. The present invention relates to a plasma oxidation or nitriding method, and a plasma oxidation or nitriding apparatus used therefor.

2. Description of the Related Art Conventionally, the plasma oxidation method described below with reference to FIG. 2 has been proposed.

That is, a sample 2 made of a semiconductor or a metal is brought into good electrical contact with the electrode plate 3 arranged in the lower portion of the plasma oxidation chamber 1 in the plasma oxidation chamber 1, and the sample 2 2 is heated by a heater 4 arranged below the electrode plate 3 as required, and the electrode plate 3 and another electrode arranged above the plasma oxidation chamber 1 so as to face the sample 2. Exhaust gas connected to the plate 5 with the DC power supply 6 connected to the plasma oxidation chamber 1 from the lower part thereof via the valve 9 while the electrode plate 3 side is connected in a positive polarity. Oxygen 8 is supplied from above to the inside of the plasma oxidation chamber 1 via the gas supply chamber 7 while exhausting using the pump 10 for plasma, and the oxygen 8 is supplied around the upper portion of the plasma oxidation chamber 1. For generating electromagnetic waves that are placed in the The electromagnetic wave radiated from the magnet 11 is excited to generate plasma, and the oxygen plasma 13 is applied to the sample 2 to oxidize the surface of the sample 2.

The above is an example of the conventionally proposed plasma oxidation method.

Further, conventionally, a plasma oxidation method described below with reference to FIG. 3 has also been proposed.

Incidentally, in FIG. 3, parts corresponding to those in FIG. 2 are designated by the same reference numerals.

That is, a sample 2 made of a semiconductor or a metal is erected and placed in the plasma oxidation chamber 1 using a holder 14, and the plasma oxidation chamber 1 is provided with a valve 9 on its side. While evacuating using the exhaust pump 10 connected through the inside, from the side opposite to the side where the valve 9 is connected to the inside of the plasma oxidation chamber 1, as viewed from the sample 2,
Oxygen 8 is supplied through the gas supply pipe 7 and the oxygen 6
For generating an electromagnetic wave, which is arranged around a portion between the position corresponding to the position where the sample 2 in the plasma oxidation chamber 1 is arranged and the gas supply pipe 7 side and which is connected to the high frequency power supply 12. It is excited by electromagnetic waves radiated from the coil 11 and turned into plasma, and the oxygen plasma 13 is applied to one surface (rear surface) 2b of the sample 2 and the other surface (rear surface) 2a of the sample 2 is irradiated with the plasma 13. The plasma 13 'obtained by diffusion is irradiated, and thereby the front surface 2a and the back surface 2b of the sample 2 are oxidized.

The above is another example of the conventionally proposed plasma oxidation method.

Problems to be Solved by the Invention In the case of the conventional plasma oxidation method shown in FIG.
When a positive electric potential is applied from the DC power supply 6 to the oxygen plasma 13, the oxygen plasma 13 is irradiated.
Negative oxygen ions constituting 13 are drawn into the sample 2 at a speed according to the value of the positive potential applied thereto, and the negative oxygen ions cause the semiconductor or metal that is the material of the sample 2 to Sample 2 using the mechanism of oxidation
The surface of is being oxidized.

Therefore, by adjusting the voltage of the DC power supply 6,
The oxidation rate of the surface of the sample 2 can be controlled relatively easily, and thus the thickness of the oxide layer formed on the surface of the sample 2 by the oxidation can be controlled relatively easily.

However, in the case of the conventional plasma oxidation method shown in FIG. 2, in order to give a positive potential to the sample 2, the sample 2 is attached to the electrode plate 3
Need to contact.

Therefore, the sample 2 may be contaminated by the material of the electrode plate 3.

Further, since it is difficult to bring the sample 2 into contact with the electrode plate 3 uniformly over the entire area of the sample 2, it is difficult to apply a uniform positive potential to the sample 2 over the entire area. Therefore, there is a drawback that it is difficult to oxidize the surface of the sample 2 to a uniform thickness in each part.

In the case of the conventional plasma oxidation method shown in FIG. 3, the back surface 2b of the sample 2 is irradiated with oxygen plasma 13, and the surface 2a of the sample 2 is supplied with plasma 13 'obtained by diffusion of the plasma 13. Since the potential of the plasma 13 ′ is lower than that of the plasma 13 when irradiated, the back surface 2b of the sample 2 is negative with respect to the plasma 13 even though the sample 2 does not apply any potential to it from the DC power supply. Charged to
Since the front surface 2a of the sample 2 is in a state of being positively charged with respect to the plasma 13 ', the back surface 2b side of the sample 2 has a plasma.
The positive oxygen ions forming 13 are drawn, and the negative oxygen ions forming the plasma 13 'are drawn on the surface 2a side of the sample 2. Therefore, by these positive and negative oxygen ions The front surface 2a and the back surface 2b of the sample 2 are oxidized by utilizing the mechanism that the semiconductor 2 or the metal that is the material of the sample 2 is oxidized on the back surface 2b and the front surface 2a. In this case, the surface 2a of the sample 2 is thicker than the back surface 2b.

Therefore, in the case of the conventional plasma oxidation method shown in FIG.
It is not necessary to bring the sample 2 into contact with the electrode plate 3 as in the case of the conventional plasma oxidation method described above with reference to FIG.
Therefore, unlike the case of the conventional plasma oxidation method described above with reference to FIG. 2, there is no fear that the sample 2 is contaminated by the material of the electrode plate 3.

However, in the case of the conventional plasma oxidation method shown in FIG. 3, if the energy of the electromagnetic wave radiated from the electromagnetic wave generating coil is adjusted by controlling the high frequency current supplied to the electromagnetic wave generating coil 11, the sample 2 Since the potentials of the plasmas 13 and 13 'irradiating the front surface 2a and the back surface 2b of the sample 2 cannot be controlled, the front surface 2a and the back surface of the sample 2
It cannot be said that the oxidation rate of 2b cannot be controlled at all, but it is extremely difficult to control it with good reproducibility, effectively and easily.

Therefore, the thickness of the oxide layers formed on the surfaces 2a and 2b of the sample 2 by the oxidation cannot be controlled easily with good reproducibility, and the oxide layers are relatively thick. It had a drawback that it could not be formed.

SUMMARY OF THE INVENTION Accordingly, the present invention provides a novel plasma oxidation or nitridation method that does not have the drawbacks described above with respect to the conventional plasma oxidation method described above with reference to FIGS. 2 and 3. The purpose is to propose a new plasma oxidation or nitriding device used for this purpose.

The plasma oxidation or nitriding method according to the present invention is a plasma of oxygen or a gas containing oxygen, or nitrogen or a gas containing nitrogen on the surface of the sample while the back surface of the sample made of a semiconductor or a metal is irradiated with positive ions. The surface of the sample is oxidized or nitrided by irradiating with.

Further, the apparatus for plasma oxidation or nitridation according to the present invention,
It has a plasma generation / irradiation chamber, an ion irradiation chamber, and sample holding means for holding a sample made of a semiconductor or a metal so that its front and back surfaces face the plasma generation / irradiation chamber and the ion irradiation chamber, respectively. A chamber for plasma oxidation or nitriding, a means for supplying oxygen or a gas containing oxygen, or a gas containing nitrogen or nitrogen to the chamber for plasma generation / irradiation, and oxygen or oxygen introduced into the chamber for plasma generation / irradiation. Means for converting the gas containing gas or nitrogen or a gas containing nitrogen into plasma, means for exhausting the plasma generation / irradiation chamber, means for irradiating the ion irradiation chamber with positive ions from the positive ion generation means, and ion irradiation And a means for exhausting the chamber.

According to the plasma oxidation or nitriding method according to the present invention, plasma of oxygen or a gas containing oxygen, or nitrogen or a gas containing nitrogen is applied to the surface of the sample while the back surface of the sample is irradiated with positive ions. The negative oxygen or nitrogen ions forming the plasma of oxygen or a gas containing oxygen, or nitrogen or a gas containing nitrogen, when irradiated with, of the positive ions irradiating the back side of the sample. It is drawn in at a speed and flow rate according to the current value, and the negative oxygen or nitrogen ions cause the semiconductor or metal that is the material of the sample to
The surface of the sample is oxidized or nitrided by a mechanism of oxidizing or nitriding.

In this case, it is not necessary to bring the sample into contact with the electrode plate as in the case of the conventional plasma oxidation method described above with reference to FIG.

Therefore, unlike the case of the conventional plasma oxidation method described above with reference to FIG. 2, there is no fear that the sample is contaminated by the material of the electrode plate.

Further, as described above, according to the plasma oxidation or nitriding method of the present invention, when the surface of the sample is oxidized or nitrided by the mechanism described above, the current value of the positive ions irradiated to the back surface of the sample is Can be adjusted to.

Therefore, the rate of oxidation or nitridation of the surface of the sample can be controlled relatively easily, and thus the thickness of the oxide layer or the nitride layer formed by the oxidation or nitridation can be controlled easily. it can.

Further, according to the apparatus for plasma oxidization or nitridation according to the present invention, the surface of the sample is oxidized or nitrided by using the apparatus for plasma oxidation or nitridation according to the plasma oxidation or nitriding method according to the present invention. be able to.

EXAMPLE Next, with reference to FIG. 1, an example of a plasma oxidation or nitriding method according to the present invention and an example of a plasma oxidation or nitriding apparatus according to the present invention used therefor will be described. An example of a plasma oxidation method according to the present invention using an example of an apparatus for nitriding will be described.

A sample 2 made of semiconductor or metal is placed in a plasma oxidizing or nitriding chamber 21 having a plasma generating / irradiating chamber 22 and an ion irradiating chamber 23 by an appropriate sample holding means 24.
The front surface 2a and the back surface 2b are respectively the plasma generation / irradiation chamber 22
And the ion irradiation chamber 23 so as to face the ion irradiation chamber 23 and separate the plasma generation / irradiation chamber 22 and the ion irradiation chamber 23 by the sample 2, and the ion irradiation chamber 23
While being evacuated from its side portion using an exhaust pump 10 'connected thereto via a valve 9', inside the ion irradiation chamber 23, from below, the ion irradiation chamber 23
By supplying positive ions 26 from a positive ion generator 25 that generates positive ions of hydrogen, helium, etc., which itself is a notification, to irradiate the back surface 2b of the sample 2 with the positive ions 26. The plasma generation / irradiation chamber 22 while
Oxygen 8 is introduced into the plasma generation / irradiation chamber 22 from above through the gas supply pipe 7 while evacuating from below with the exhaust pump 10 connected thereto via the valve bu9. The oxygen 8 supplied is excited by the electromagnetic wave radiated from the electromagnetic wave generating coil 11 arranged around the upper part of the plasma generation / irradiation chamber 22 and connected to the high frequency power source 12, and is made into plasma to generate oxygen. Plasma 13
Is irradiated on the surface 2a of the sample 2 to oxidize the surface 2a of the sample 2.

In this case, the ion detector 27 arranged in the ion irradiation chamber 23 of the plasma generation / irradiation chamber 21 detects the irradiation amount of the back surface 2b of the sample 2 by the positive ions 26, and the detection output indicates Room for ion irradiation from positive ion generator 25
Positive ions 26 supplied to the inside of the sample 23 to irradiate the back surface 2b of the sample 2 26
Control the amount of current.

The above is the embodiment of the plasma oxidation method according to the present invention.

According to the plasma oxidation method of the present invention, when the surface 2a of the sample 2 is irradiated with the oxygen plasma 13 while the back surface 2b of the sample 2 is irradiated with the positive ions 26, the oxygen plasma 13 is emitted. The negative oxygen ions that make up the sample 2
By the mechanism in which the semiconductor 2 or the metal that is the material of the sample 2 is oxidized by the negative oxygen ions which are drawn into the inside of the back surface 2b at a speed and flow rate according to the current value of the positive ions 26, The surface 2a of the sample 2 is oxidized.

In this case, it is not necessary to bring the sample 2 into contact with the electrode plate as in the case of the conventional plasma oxidation method described above with reference to FIG.

Therefore, unlike the case of the conventional plasma oxidation method described above with reference to FIG. 2, there is no fear that the sample 2 is contaminated by the material of the electrode plate.

Further, as described above, according to the plasma oxidation method of the present invention, when the surface 2a of the sample 2 is oxidized or nitrided by the mechanism described above, the current value of the positive ions 26 with which the back surface 2b of the sample 2 is irradiated is Can be easily adjusted by the positive ion generator 25.

Therefore, the oxidation rate of the surface 2a of the sample 2 can be controlled relatively easily, and thus the thickness of the oxide layer formed by the oxidation can be easily controlled.

In the above description, the case where oxygen is used in the plasma oxidation method according to the present invention has been described, but it will be apparent that the same action and effect as described above can be obtained by using a gas containing oxygen.

Further, in the above description, the plasma oxidation method according to the first invention of the present application has been described. However, in the plasma oxidation method according to the first invention of the present application, nitrogen or nitrogen such as ammonia gas is used instead of oxygen used therefor. By using the contained gas, the plasma nitriding method according to the present invention can be performed, and various modifications and changes can be made without detracting from the spirit of the present invention.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing an embodiment of a plasma oxidation or nitriding method according to the present invention and a plasma oxidation or nitriding apparatus used therefor. 2 and 3 are schematic diagrams showing a conventional plasma oxidation method.

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Claims (2)

[Claims] 1. A method of irradiating the surface of the sample with oxygen or a gas containing oxygen or nitrogen or a gas containing nitrogen while the back surface of the sample made of a semiconductor or a metal is irradiated with positive ions. A plasma oxidation or nitriding method, characterized in that the surface of the sample is oxidized or nitrided. 2. A plasma generation / irradiation chamber, an ion irradiation chamber, and a sample made of a semiconductor or a metal are held so that their front and back surfaces face the plasma generation / irradiation chamber and the ion irradiation chamber, respectively. A chamber for plasma oxidization or nitriding having a sample holding means for supplying the oxygen, a means for supplying oxygen or a gas containing oxygen, or a gas containing nitrogen or nitrogen to the chamber for plasma generation / irradiation; A means for converting oxygen or a gas containing oxygen, or a gas containing nitrogen or a gas containing nitrogen introduced into the chamber into a plasma, a means for exhausting the plasma generation / irradiation chamber, and a means for generating positive ions in the ion irradiation chamber. A device for plasma oxidation or nitriding, comprising: a means for irradiating the positive ions of 1. and a means for evacuating the ion irradiation chamber.