JPH06302535A - Annealing method with electron beam - Google Patents

Abstract

PURPOSE:To provide a large radiation beam spot even when the diameter of electron beam is small when a semiconductor layer is annealed by irradiation with an electron beam. CONSTITUTION:A point-like electron beam 9 is made to fall on the surface of a semiconductor layer 3 at a low angle theta (presumably five degrees or less). Then, irradiation beam spot 14 enlarges. Therefore, even the diameter d of the point-like electron beam 9 is small, the irradiation beam spot 14 can be enlarged. As a result, when scanning speed, beam intensity, etc., are identical with those of irradiation in the vertical direction, temperature rising at a unit area and time can be smaller. Further, the time required for annealing, while the entire semiconductor layer 3 is scanned, can be shortened.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electron beam annealing method.

[0002]

2. Description of the Related Art In the technical field of semiconductor devices such as thin film transistors, by irradiating with an electron beam to anneal, crystal defects are removed by removing lattice defects in a semiconductor layer, and impurity atoms between lattices are removed. The distortion of the lattice may be removed by substituting the points.

FIG. 5 shows a schematic structure of a conventional electron beam annealing apparatus. This annealing device includes a device body 1 having a closed structure. An anode / substrate holder 2 is horizontally provided in the lower part of the apparatus main body 1. The semiconductor layer 3 is formed on the upper surface of the anode / substrate holder 2.
The substrate 4 provided with is held. An electron gun 5 is provided above the center of the substrate holder 2 and inside the apparatus main body 1. The electron gun 5 includes a filament 6 that is heated to emit electrons and a cathode 7. Then, when a voltage is applied from the DC power supply 8 between the cathode 7 and the anode / substrate holder 2, an emission current flows during that time, whereby electrons emitted from the filament 6 are accelerated, and the point electron beam 9 is emitted. Then, the semiconductor layer 3 on the substrate 4 is irradiated. Between the electron gun 5 and the anode / substrate holder 2, X
An X-direction focusing coil 10 for giving a deflection force in a direction,
A Y-direction focusing coil 11 for providing a Y-direction deflection force to the point electron beam 9 is provided. A predetermined portion of the lower part of the apparatus body 1 is connected to a vacuum pump (not shown) via a pipe 13 in which a valve 12 is interposed.

When the semiconductor layer 3 on the substrate 4 is annealed by this annealing apparatus, first, the valve 12 is opened and the gas inside the apparatus body 1 is sucked by a vacuum pump to make the inside of the apparatus body 1 high vacuum. Put in a state. Then, a point electron beam 9 is emitted from the electron gun 5, and the emitted point electron beam 9 is given a deflection force in the X direction and the Y direction by both focusing coils 10 and 11, and the point electron beam after the deflection is applied. Irradiate the semiconductor layer 3 on the substrate 4 while scanning 9. Thus, the semiconductor layer 3 on the substrate 4 is wholly annealed.

[0005]

However, in such a conventional annealing method using an electron beam, the anode / substrate holder 2 is horizontal and is directly above the semiconductor layer 3 on the substrate 4 held on the upper surface thereof. Since the point-shaped electron beam 9 is emitted from the electron gun 5 arranged at, the beam diameter of the point-shaped electron beam 9 becomes the irradiation beam spot as it is. Since the beam diameter of the point electron beam 9 is small, the irradiation beam spot is also small. Therefore, not only is it difficult to control the temperature of the semiconductor layer 3 on the substrate 4 in the depth direction, but also the substrate 4 and the anode are overheated. There is a problem in that the substrate holder 2 may be heated to a high temperature and the substrate 4 may be distorted. Further, when the irradiation beam spot is small, it takes time to anneal while scanning the entire semiconductor layer 3 on the substrate 4, and there is a problem that throughput is low. An object of the present invention is to provide an annealing method using an electron beam capable of increasing the irradiation beam spot.

[0006]

According to the present invention, the semiconductor layer is annealed by irradiating the surface of the semiconductor layer with an electron beam obliquely.

[0007]

According to the present invention, since the semiconductor layer is irradiated with the electron beam obliquely with respect to the surface thereof, the irradiation beam spot spreads. Therefore, even if the beam diameter of the electron beam is small, the irradiation beam spot is large. can do.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a schematic structure of an annealing apparatus using an electron beam for explaining an embodiment of the present invention. In this figure, the same reference numerals are given to the same names as those in FIG. 5, and the description thereof will be omitted as appropriate. In this annealing apparatus, an electron gun 5 is provided diagonally above and to the left of the horizontally arranged anode / substrate holder 2. Along with this, both focusing coils 10 and 11 provided between the electron gun 5 and the anode / substrate holder 2 are appropriately inclined.

In this annealing apparatus, the dot-shaped electron beam 9 emitted from the electron gun 5 is applied to the semiconductor layer 3 on the substrate 4 held horizontally on the anode / substrate holder 2 from the upper left to the surface thereof. It will be irradiated. As a result, for example, as shown in FIG. 2, since the dot-shaped electron beam 9 is irradiated onto the surface of the semiconductor layer 3 at a low angle θ (preferably 5 ° or less), the irradiation beam spot 14 spreads. Become. By the way, compared with the irradiation beam spot by the dot-like electron beam 9 from the vertical direction shown by the one-dot chain line in FIG. 2, if the angle θ is 5 ° or less, it can be expanded ten times or more. Therefore, the irradiation beam spot 14 can be increased even if the beam diameter d of the point electron beam 9 is small. As a result, if the scan speed, the beam intensity, etc. are the same as in the case of the conventional irradiation from the vertical direction, the temperature rise of the unit area per unit time is smaller than that in the conventional case, and the semiconductor on the substrate 4 is correspondingly increased. Not only can the temperature control of the layer 3 in the depth direction be facilitated, but also the substrate 4 and the like can be prevented from reaching a high temperature. Further, if the irradiation beam spot 14 is large, the time for annealing while scanning the entire semiconductor layer 3 on the substrate 4 can be shortened,
Therefore, the throughput can be improved. Furthermore, a small increase in the unit area per unit time is suitable for a low temperature process. For example, when light ions having a low lattice defect generation rate are implanted into the semiconductor layer 3 on the substrate 4 at a low temperature and annealed at a low temperature, an electrically active implantation layer can be obtained and the temperature of the substrate 4 is raised. Can be sufficiently suppressed.

Although the semiconductor layer 3 on the substrate 4 is irradiated with the point electron beam 9 in the first embodiment described above, the invention is not limited to this. For example, as in the second embodiment shown in FIGS. 3A and 3B in which the same parts as those in FIG. A pair of high-frequency plates 15 is provided between the dual-purpose substrate holder 2 and the dual-purpose substrate holder 2.
The high frequency electric field causes the point electron beam 9 to be deflected at high speed in the Y direction to irradiate the semiconductor layer 3 on the substrate 4 with the pseudo linear electron beam 16, and the focusing coil 10 in the X direction
Alternatively, the scanning may be performed relatively slowly in the X direction. In this case, the frequency of high-speed deflection is set to 2
When the frequency is increased to 00 kHz and 2 MHz, the number of reciprocations (frequency) of the electron beam deflected in the Y direction within the Y direction deflection range increases, and consequently the movement of the electron beam deflected in the Y direction in the Y direction. Is faster than the thermal response of the semiconductor layer 3 due to the irradiation of the electron beam, and as a result, the temperature of the semiconductor layer 3 in the irradiation range in the Y direction is made uniform, and uniform annealing can be performed.

Further, in the above-described first embodiment, the electron gun 5 is provided obliquely above and to the left of the horizontally arranged anode / substrate holder 2, but the present invention is not limited to this. For example, as in the third embodiment shown in FIG. 4 in which the same parts as those in FIG. 5 are designated by the same reference numerals, the anode / substrate holder 2 is appropriately tilted, and the electron gun 5 is provided right above the central portion thereof. You may do it. By doing so, the installation space of the device can be reduced as compared with the first embodiment shown in FIG.

[0012]

As described above, according to the present invention, the semiconductor layer is irradiated with the electron beam obliquely with respect to the surface thereof. Therefore, even if the beam diameter of the electron beam is small, the irradiation beam spot can be formed. The temperature of the semiconductor layer can be increased, and the temperature control in the depth direction of the semiconductor layer can be facilitated. In particular, in the case of a point electron beam, the throughput can be improved.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of an electron beam annealing apparatus for explaining a first embodiment of the present invention.

FIG. 2 is a diagram for explaining a relationship between a beam diameter of a point electron beam and an irradiation beam spot.

FIG. 3A is a schematic configuration diagram of an electron beam annealing apparatus for explaining a second embodiment of the present invention; FIG.
Is a plan view of part of it.

FIG. 4 is a schematic configuration diagram of an electron beam annealing apparatus for explaining a third embodiment of the present invention.

FIG. 5 is a schematic configuration diagram of a conventional electron beam annealing apparatus.

[Explanation of symbols]

 3 Semiconductor layer 9 Point electron beam 14 Irradiation beam spot

Claims (1)

[Claims] 1. An annealing method using an electron beam, which comprises irradiating a semiconductor layer with an electron beam obliquely with respect to a surface thereof to anneal the semiconductor layer.