JPH11224861A - Activation method and activation device for semiconductor impurity - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an activation method and activation device for a semiconductor impurity, capable of efficiently and surely activating impurities even if a laser of relatively small output is used. SOLUTION: An SiC substrate 1 and an SiC thin film 2, to which impurity elements have been added, and irradiated with laser beams 5 of a wavelength longer than the wavelength for causing the band end adsorption of a semiconductor or irradiated with the laser beams 5 of a wavelength absorbed by the vibration of bonding between the constituent element of the semiconductor and the impurity element, the wavelength of 9-11 μm for instance. Especially, in the case of adding Al to SiC, they are irradiated with the laser beam 5 whose wavelength is 9.5-10 μm. As a result, even if a laser device of relatively small output is used, the impurities are efficiently and surely activated, and especially the activation of p-type impurities of SiC which were difficult conventionally is performed very efficiently.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of activating a semiconductor impurity required for manufacturing a semiconductor device, for example, for activating an impurity implanted into silicon carbide (SiC) or the like.
And an activation device.

[0002]

2. Description of the Related Art At the time of forming a semiconductor device using silicon (Si), which is currently most common as a semiconductor, an impurity is added to Si by ion implantation or the like, and then an electric furnace or flash lamp annealing is used. , 90
By heating to about 0 to 1100 ° C and performing heat treatment,
Activation of impurities is performed.

In recent years, silicon carbide (S) having excellent power characteristics (high withstand voltage, large allowable current), high frequency characteristics, and environmental resistance has been developed.
A semiconductor device using iC) has attracted attention. This Si
C is more difficult to implant and activate than Si. Therefore, C may be added with impurities during the formation of SiC,
Ion implantation is performed while heating to a high temperature of about 0 to 1000 ° C., and further, T. Kimoto, et al .: Journal of Ele
ctronic Materials, Vol.25, No.5, 1996, pp.879-884
And the like, a technique of activating impurities by performing heat treatment at a high temperature of 1400 to 1600 ° C. has been proposed.

However, the method of activating impurities by the heat treatment as described above requires a step of heating Si or the like by an electric furnace or the like, so that the activation requires a relatively long time and the productivity is reduced. It is difficult to improve. This problem is more remarkable when using SiC because a higher temperature heat treatment is required, and it is particularly difficult to form a semiconductor layer in which a large number of p-type dopant elements are activated.

Therefore, as described in, for example, Japanese Patent Application Laid-Open No. 7-22311, an amorphous Si film in which the concentrations of carbon, nitrogen and oxygen are equal to or lower than a predetermined value is irradiated with a laser beam and laser-annealed. Amorphous S
By forming a region where the amorphous region and the solid-phase ordered region are mixed without melting the i-film, implanting impurity ions by ion implantation, irradiating with a laser beam having a wavelength of 248 nm, and performing laser annealing. 2. Description of the Related Art There is known a technique of making an impurity region semi-amorphous and activating an impurity. Although the publication discloses that the mobility of carriers can be improved by the above-described method as compared with amorphous Si, it does not disclose laser annealing for semiconductors other than amorphous Si.

The laser light used for laser annealing for crystallization (activation) of a semiconductor as described above includes:
For more details, see, for example, Y. Morita, et al .: Jpn J. App
As described in l. Phys., Vol. 2, No. 2 (1989) pp. L309-L311, excimer laser light having a wavelength shorter than the wavelength at which band edge absorption of the Si film occurs is used. Was.
Laser light of such a wavelength is used by exciting and ionizing electrons of atoms constituting a semiconductor by the energy of the laser light, and converting a part of the energy into lattice vibration energy of the constituent atoms. This is because the semiconductor is instantaneously heated to a high temperature to promote crystallization (activation).

[0007]

However, in the conventional impurity activation by laser annealing, the efficiency of energy utilization is low, and a laser device having a relatively large output is required to instantaneously heat a semiconductor to a high temperature. In addition, there is a problem that the manufacturing cost tends to increase, and it is not always easy to reliably activate impurities and the like, and it is difficult to form a semiconductor element having good characteristics. Had. In particular, with respect to activation of p-type impurities and the like in SiC, it is more difficult to form a semiconductor element having good characteristics.

In view of the above points, the present invention provides a semiconductor impurity activation method and an activation method capable of efficiently and reliably activating an impurity even if a laser device having a relatively small output is used. It is intended to provide equipment.

[0009]

In order to solve the above-mentioned problems, the present invention provides a method of activating semiconductor impurities by irradiating a semiconductor containing a main semiconductor element and an impurity element with light to activate the impurity elements. The method is characterized in that the irradiation light is light having a wavelength longer than a wavelength at which band edge absorption of the semiconductor occurs. Further, the irradiation light is
It is characterized in that the light is substantially at a wavelength at which resonance absorption occurs due to inherent vibration in the bond between the main semiconductor element and the impurity element.

That is, in the case of light having a wavelength shorter than the wavelength causing band edge absorption as used in conventional activation, the electrons of atoms constituting a semiconductor are excited and ionized by the energy of the irradiated light. By converting a part of the energy into lattice vibration energy of constituent atoms, the semiconductor is instantaneously heated to a high temperature to activate the semiconductor. It has been found that by irradiating light of various wavelengths, lattice vibration between an impurity element and a constituent element of a semiconductor can be directly excited and activated, and the present invention has been completed. Therefore, a laser device with high activation efficiency and low output can be used, and good impurity activation can be easily performed.

Specifically, for example, when the main semiconductor element is silicon carbide and the impurity element is any of aluminum, boron, and gallium, the wavelength at which band edge absorption occurs (about 6H-SiC, 3 eV: up to 0.4
By irradiating light with a wavelength longer than 1 μm), for example, 9 μm or more and 11 μm or less, a p-type silicon carbide semiconductor having good characteristics can be easily formed. Especially,
In the case of aluminum, it is more preferable to use a wavelength of 9.5 to 10 μm.

Further, the present invention further uses the laser light having the above-described wavelength to focus the laser light in the vicinity of the surface of the semiconductor, and to set the focus position of the laser light on the semiconductor. The method is characterized in that the laser light is irradiated so as to be located at a predetermined distance from the surface to the light source side of the laser light. More specifically, for example, a plume generated when the focal point of the laser light is brought closer to the surface of the semiconductor from a position closer to the light source side of the laser light than the surface of the semiconductor is detected. The method is characterized in that the laser beam is irradiated by controlling the focal point of the light to be near the position where the plume starts to be detected.

By setting and controlling the focal point position in this way, the degree of activation can be easily further improved.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An example in which aluminum (Al) ions are implanted as impurities into silicon carbide (SiC) and activated will be described below.

(Semiconductor Substrate Manufacturing Process) First, an outline of a semiconductor substrate manufacturing process including a laser annealing process will be described with reference to FIG.

(1) As shown in FIGS. 1A and 1B, SiC made of single crystal 6H-SiC (hexagonal silicon carbide)
Epitaxial growth by sublimation on substrate 1
An SiC thin film 2 made of single crystal 6H—SiC is formed. As a method and conditions for forming the SiC thin film 2, known ones can be applied, and a description thereof will be omitted. here,
The above-mentioned SiC substrate 1 and SiC thin film 2 are each added with nitrogen gas (N ₂ ) during the crystal growth,
It is doped with N at a concentration of 0 ¹⁸ cm ⁻³ to form an n-type. Note that the SiC substrate 1 and the SiC thin film 2
The substrate is not limited to the one made of H-SiC, but may be another crystal form, or a substrate made of silicon (Si) may be used. Further, the SiC thin film 2 may be formed by growing a single crystal not only by the sublimation method but also by a CVD method or the like. Further, N doping may not necessarily be performed depending on a semiconductor element (device) to be manufactured using a semiconductor to be formed.

(2) As shown in FIG.
Al ions 3 are implanted into the C thin film 2 by ion implantation,
A p-type impurity added layer (doping layer) 4 is formed near the surface of the SiC thin film 2. More specifically, the ion implantation is performed at a temperature of 800 ° C., an acceleration energy: 130 keV, and an implantation amount: 1.22 × 10
¹⁵ cm ^-2 acceleration energy: 80 keV Implantation amount: 3.9 × 10 ¹⁴
cm ^-2 acceleration energy: 40 keV Implantation amount: 3.9 × 10 ¹⁴
cm ^-2 in three stages, as shown in FIG.
Over a thickness of about 2000 mm from the surface of the thin film 2, 10
^The process is performed so that the impurity-added layer 4 in which the region having the Al concentration of ²⁰ cm ^-3 is distributed is formed.

The impurities for forming the p-type impurity-added layer 4 include, in addition to Al, boron (B),
Any of gallium (Ga) and the like may be used. However, in doping the SiC thin film, it is preferable to use Al in the case of a p-type having a shallow impurity level. Further, the n-type impurity-added layer 4 may be formed using phosphorus (P) or the like. In that case, at the time of crystal growth of the SiC substrate 1 and the SiC thin film 2, Al or the like may be added as needed instead of the above-mentioned addition of N. Furthermore, the temperature at the time of implantation, the acceleration energy and concentration of the implantation, and whether the ion implantation is performed under one-step or multi-step conditions are as follows.
What is necessary is just to set according to the structure of the semiconductor element (device) manufactured using the semiconductor, the thickness of a doping layer, etc.
Although the temperature at the time of implantation may be room temperature, it is easier to activate the impurities by a subsequent laser annealing step by performing ion implantation by heating to 500 ° C. or more. Further, other known various ion implantation methods may be used.

(3) As shown in FIG. 1D, the impurity-doped layer 4 is irradiated with a laser beam 5 having a wavelength in the infrared region while scanning in a horizontal and vertical direction at a predetermined scanning frequency. An activation doping layer 6 in which impurities are uniformly activated over the entire surface is formed. For this activation,
Details will be described below.

(Laser Annealing Apparatus) Next, the laser annealing apparatus will be described.

As shown schematically in FIG. 3, this laser annealing apparatus has a SiC thin film 2 formed thereon and an Al-ion-implanted SiC substrate 1 (hereinafter simply referred to as “SiC substrate 1”).
Called. ) Are arranged, and a free electron laser 22 having a variable oscillation wavelength is provided. The chamber 21 includes an optical window 7, a reflecting mirror 8, a lens 9 for condensing and positioning a laser beam, a galvanometer mirror 10 for reflecting and scanning a laser beam, and
A sample stage 11 on which the iC substrate 1 is placed is provided.
The optical window 7, the reflection mirror 8, and the lens 9 are made of, for example, ZnSe. The sample stage 11 is configured to move the SiC substrate 1 in the vertical and horizontal directions in FIG. 1 by a sample stage moving mechanism 16 including a piezoelectric actuator or a stepping motor (not shown). In the vicinity of the sample stage 11, there is provided a photodetector 15 for detecting a spark-like light emission (plume) 14 generated from the surface of the SiC substrate 1 by irradiating a laser beam. Sample stage moving mechanism 16
Is controlled, and the sample stage 11 moves up and down.

(Details of Laser Annealing Process) The laser annealing process using the laser annealing apparatus as described above will be described in detail.

In this laser annealing process, by appropriately setting the focal point of the laser beam 5 by the lens 9 and the wavelength of the laser beam 5, good activation of impurities is performed.

First, the adjustment of the focal position will be described.
The wavelength of the laser light 5 is set to 10.2 μm,
Focus position 1.5 mm above the surface of the SiC substrate 1
Various settings were made from the position (1) to the position -2.0 mm inside (the back side of the SiC substrate 1) to activate the impurities. For each of the obtained SiC substrates 1, a He-Cd laser (wavelength: 325 nm) was used as excitation light to measure the degree of impurity activation, and the measurement sample temperature was 8K (-26).
(5 ° C.), the photoluminescence spectrum was measured. FIG. 4 shows the measurement results. About 2.6 in FIG.
The emission appearing near eV (wavelength: 480 nm) is S
This is photoluminescence (DA pair emission) due to recombination between a donor (D) -acceptor (A) pair caused by an activated impurity element in the iC substrate 1, and DA pair emission is generated as the number of activated impurities increases. The strength of is increased.
Accordingly, when the focal position of the laser beam 5 is slightly (0.5 to 1.0 mm) above the surface of the SiC substrate 1 (indicated by ○ and △ in the figure), the DA pair emission appears most strongly. It was confirmed that the activation of impurities was most efficiently performed. On the other hand, when focusing is performed from the surface of the SiC substrate 1 toward the inner side (●, ▲,
In (■, ▼), the intensity of the DA pair emission decreases. In the case where the surface of the SiC substrate 1 is slightly inside from the surface of the SiC substrate 1 (indicated by ● and ▲ in the figure), the surface of the SiC substrate 1 is blackened, and the surface of the SiC substrate 1 is modified or deteriorated. It is thought that it was done. Therefore, the focal position of the laser beam 5 is
By setting it slightly above the surface of the C substrate 1, good activation can be performed.

The control of the focal position as described above can be actually performed, for example, as follows. That is, the state where the focal position of the laser light 5 is slightly higher than the surface of the SiC substrate 1 is caused by the irradiation of the laser light 5
Since this corresponds to a state where the plume 14 starts to be generated from the surface of the C substrate 1, the generation of the plume 14 is detected by the photodetector 15, and the SiC substrate 1 is moved up and down by the sample stage moving mechanism 16 to generate the plume. By performing the feedback control so that the starting state is maintained, it is possible to optimize the position of the irradiation surface and to perform good activation. Here, in order to prevent the SiC substrate 1 from being modified or deteriorated by the irradiation of the laser beam 5, the focus position is first set once to a position distant from the surface of the SiC substrate 1, and then brought closer to the SiC substrate 1. It is preferable to control as follows.

The method of controlling the focal position is not limited to the method described above. For example, the position of the surface of the SiC substrate 1 may be detected and controlled by a position sensor. When the distance between the focal position and the surface of the SiC substrate 1 is maintained with good reproducibility, the position of the sample table 11 is set in advance,
It may not be controlled during laser annealing.

Further, by controlling the focal position as described above, the irradiation intensity of the laser light on the SiC substrate 1 can be substantially easily controlled. However, the laser light is controlled based on the detection of the plume. The irradiation intensity may be controlled by performing modulation or the like.

Next, the wavelength of the laser beam 5 will be described. The wavelength of the laser beam 5 is variously set from 10.64 to 9.43 μm to activate the impurities, and the obtained Si
The photoluminescence spectrum of the C substrate 1 was measured in the same manner as in the case of the focal position. FIG. 5 shows the measurement results. (Note that, in the figure, the spectra corresponding to the respective wavelengths are drawn shifted by 0.05 graduations on the vertical axis for the sake of convenience.) As is apparent from FIG.
Light in the wavelength region of １１11 μm, and further in the wavelength region of 9.5 μm to 10 μm has a large DA pair emission intensity and a large effect of activating Al.

Here, SiC has absorption wavelengths of 12.6 μm and 10.3 μm corresponding to TO phonon and LO phonon in the interstitial vibration of Si—C, and the absorption wavelength of Si—N is 11.9 μm. On the other hand, when laser light having a wavelength of 9.8 to 9.6 μm is irradiated as shown in FIG.
A pair emission is maximum. Therefore, it is considered that the activation of Al is greatly influenced by absorption in the bond between Si or C and the impurity element Al.

That is, in the conventional activation, in order to give energy to the electron system of the semiconductor to be processed, a wavelength (6) such as an excimer laser which causes band edge absorption of SiC is used.
In the case of H-SiC, light having a wavelength shorter than about 3 eV (〜0.41 μm) is used, but according to the present invention, a wavelength longer than that causing band-edge absorption, particularly a semiconductor constituent element, is used. By using light having a wavelength near the wavelength at which absorption with respect to the bond with the impurity element occurs, activation is directly performed by exciting lattice vibration between the impurity element and the constituent element of the semiconductor, so that efficiency is improved. The degree of activation can be easily improved, and a laser device with a small output can be used.

The above numerical values are examples in the case where SiC and Al are used. When the constituent elements of the semiconductor and the impurity elements are different, light of a wavelength based on the above principle is irradiated according to each of them. What should I do?

In the above example, an inert gas such as argon (Ar) is sealed in the chamber 21 and laser annealing is performed in these atmospheres, or the SiC substrate 1
Heating to a temperature of about 000 ° C. or less, or adding a means such as cooling the SiC substrate 1 is advantageous in that the effects of the present invention can be further improved and controllability can be further improved. preferable.

Further, the semiconductor material is not limited to SiC but may be Si or the like, and the same effect can be obtained not only when a single crystal is used but also when an amorphous semiconductor material is used.

In the above example, a free electron laser is used for comparison at various wavelengths. However, if a predetermined wavelength as described above can be obtained, a fixed wavelength laser device is used. In particular, since a relatively long wavelength is used, productivity can be easily improved by using a CO ₂ laser or the like.

(Semiconductor Element) An example of a SiC diode formed of SiC in which impurity ions are implanted and activated in the same manner as described above will be described.

FIG. 6 is a schematic view of a manufacturing process of a SiC diode by the impurity doping method according to the present invention.

(1) As shown in FIG. 6A, an n-type S
An insulating film (oxide film) 32 is formed on the entire surface of the iC substrate 31 by thermal oxidation, CVD, sputtering, or the like.
a is formed by photolithography and etching. As the insulating film 32, an oxide film, a nitride film, or a composite film of an oxide film and a nitride film may be formed. Also,
The insulating film 32 may not necessarily be formed depending on the configuration of the element to be formed.

(2) As shown in FIG. 6B, the insulating film 3
2 is used as a mask, Al ions 33 are selectively implanted,
An Al injection layer 34 is formed.

(3) As shown in FIG. 6C, a laser beam 35 having a wavelength of 9.8 μm is irradiated to form a p-type doping layer 36 in which impurities are activated.

(4) As shown in FIG.
After the opening 32b is formed on the back surface side of the substrate 2, as shown in FIG. 6E, a nickel (Ni) film is deposited, and etching or heat treatment is performed to form an n-type ohmic electrode 37.

(5) As shown in FIG. 6F, an Al film is deposited on the p-type doping layer 36 side, and an ohmic electrode 38 is formed by performing etching and heat treatment.

FIG. 7 shows the characteristics of the diode manufactured as described above. The dotted line in the figure shows the characteristics of a diode manufactured by activating impurities by a heat treatment at 1500 ° C. described in the related art. As shown in the figure,
According to the present invention, a good diode having excellent withstand voltage characteristics and the like can be manufactured without performing heat treatment at a high temperature of 1000 ° C. or higher.

In the above example, an example in which a diode is formed has been described. However, by performing the same doping (activation), a transistor or FET (field effect) can be selected by appropriately selecting an element configuration or a mask. Various elements such as a transistor can also be manufactured.

[0044]

The present invention is embodied in the form described above and has the following effects.

That is, light having a wavelength longer than the wavelength at which band edge absorption of the semiconductor is caused, and light having a wavelength at which resonance absorption is substantially caused by inherent vibration in the bond between the main semiconductor element and the impurity element are applied. By activating the impurities, even if a laser device having a relatively small output is used, the activation of the impurities can be performed efficiently and reliably. There is an effect that the activation of impurities can be performed extremely efficiently.

[Brief description of the drawings]

FIG. 1 is a process chart showing a manufacturing process of a semiconductor substrate of an embodiment.

FIG. 2 is a graph showing impurity ion concentrations in a semiconductor substrate into which impurity ions of the embodiment are implanted.

FIG. 3 is an explanatory diagram illustrating a schematic configuration of a laser annealing apparatus according to an embodiment;

FIG. 4 is a graph showing the focus position dependence of the photoluminescence spectrum of the SiC film in the laser-annealed semiconductor substrate of the embodiment.

FIG. 5 is a graph showing the wavelength dependence of the photoluminescence spectrum of the SiC film of the laser-annealed semiconductor substrate of the embodiment on the irradiation laser light wavelength.

FIG. 6 is a process chart showing a manufacturing process of the SiC diode according to the embodiment;

FIG. 7 is a graph showing electric characteristics of the SiC diode according to the embodiment;

[Description of Signs] 1 SiC substrate 2 SiC thin film 3 Al ion 4 impurity doping layer 5 laser beam 6 activation doping layer 7 optical window 8 reflection mirror 9 lens 10 galvanometer mirror 11 sample stage 14 plume 15 photodetector 16 sample stage Moving mechanism 21 Chamber 22 Free electron laser 31 SiC substrate 32 Insulating film 32a Opening 32b Opening 33 Al ion 34 Injection layer 35 Laser light 36 P-type doping layer 37 Ohmic electrode 38 Ohmic electrode

 ──────────────────────────────────────────────────の Continued on the front page (72) Inventor Makoto Kitabatake 1006 Kazuma Kadoma, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. Inside

Claims (15)

[Claims] 1. A method for activating a semiconductor impurity, comprising irradiating a semiconductor containing a main semiconductor element and an impurity element with light to activate the impurity element, wherein the irradiation light absorbs band edge absorption of the semiconductor. A method for activating a semiconductor impurity, wherein the light has a wavelength longer than the wavelength at which it occurs. 2. The method of activating semiconductor impurities according to claim 1, wherein said irradiation light is substantially light having a wavelength at which resonance absorption occurs due to inherent vibration in the bond between said main semiconductor element and said impurity element. A method for activating a semiconductor impurity, the method comprising: 3. The method of activating semiconductor impurities according to claim 1, wherein said semiconductor is formed by ion-implanting said impurity element into a thin film or substrate comprising said main semiconductor element. Of activating semiconductor impurities. 4. The method of activating semiconductor impurities according to claim 1, wherein said main semiconductor element is silicon carbide, and said impurity element is any one of aluminum, boron, and gallium. Activating a semiconductor impurity. 5. The method of activating semiconductor impurities according to claim 4, wherein the irradiation light is light having a wavelength of 9 μm or more and 11 μm or less. 6. The method of activating semiconductor impurities according to claim 1, wherein said irradiation light is a laser beam. 7. The method of activating semiconductor impurities according to claim 6, wherein said laser light is focused near a surface of said semiconductor, and an irradiation area of said semiconductor on said focused laser light is sequentially scanned. Thereby activating the impurity element in a predetermined range of the semiconductor. 8. The method of activating semiconductor impurities according to claim 6, wherein said laser light is focused near a surface of said semiconductor, and a distance between a focus position of said laser light and a surface of said semiconductor. Controlling the irradiation intensity of the laser beam by controlling the intensity of the laser light. 9. The method for activating semiconductor impurities according to claim 6, wherein said laser light is focused near a surface of said semiconductor, and a plume generated when an irradiation intensity of said laser light is increased is detected. A method for activating a semiconductor impurity, comprising: irradiating the laser light by controlling the irradiation intensity of the laser light so as to be an irradiation intensity near the start of detection of the plume. 10. The method of activating semiconductor impurities according to claim 6, wherein said laser light is focused near a surface of said semiconductor, and said laser beam is focused on said semiconductor surface from said surface of said semiconductor. A method for activating a semiconductor impurity, comprising irradiating the laser light so as to be located at a predetermined distance from a light source side of the laser light. 11. The method of activating semiconductor impurities according to claim 6, wherein the laser light is focused near the surface of the semiconductor, and the focal point of the laser light is set to be higher than the surface of the semiconductor. Detecting a plume generated when approaching the surface of the semiconductor from the position of the light source side of the laser light, controlling the focal point of the laser light to be near the position where the plume starts to be detected, A method for activating a semiconductor impurity, which comprises irradiating a laser beam. 12. The method of activating semiconductor impurities according to claim 1, wherein said irradiating light is selectively irradiated only to a predetermined region of said semiconductor via a masking member to activate said impurity element. A method for activating a semiconductor impurity. 13. An apparatus for activating a semiconductor impurity, comprising irradiating a semiconductor containing a main semiconductor element and an impurity element with light to activate said impurity element, wherein said semiconductor impurity activation apparatus is longer than a wavelength causing band edge absorption of said semiconductor. Light source means for outputting irradiation light of a wavelength, light condensing means for condensing the irradiation light, and control means for controlling a distance between a condensing focal position of the laser light and the surface of the semiconductor. Characteristic semiconductor impurity activation device. 14. An apparatus for activating a semiconductor impurity, comprising irradiating a semiconductor containing a main semiconductor element and an impurity element with light to activate said impurity element, wherein said semiconductor impurity activation apparatus has a wavelength longer than a wavelength causing band edge absorption of said semiconductor. Light source means for outputting irradiation light of a wavelength, light detection means for detecting a plume generated by irradiation of the irradiation light, and control means for controlling the irradiation intensity of the irradiation light according to a detection result of the light detection means. An apparatus for activating semiconductor impurities, comprising: 15. An apparatus for activating a semiconductor impurity, comprising irradiating a semiconductor including a main semiconductor element and an impurity element with light to activate the impurity element, wherein the semiconductor impurity is longer than a wavelength at which band edge absorption of the semiconductor occurs. A light source means for outputting irradiation light of a wavelength; a light condensing means for condensing the irradiation light; and a condensing focal position of the irradiation light from the light source side of the irradiation light with respect to the surface of the semiconductor. A light detecting means for detecting a plume generated when approaching the surface; and a condensing focal position of the irradiation light and the semiconductor so that a condensing focal position of the irradiation light is near a position where the plume starts to be detected. Control means for controlling the distance to the surface of the semiconductor.