JPH057824B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Technical Field of the Invention The present invention relates to a composite beam irradiation device, and more particularly, to the basic structure of a beam irradiation device that can simultaneously irradiate the same point with a plurality of different beams.

(b) Background of the technology When manufacturing semiconductor devices, after impurity ions are implanted, heat treatment (annealing) is performed to activate the implanted ions. Heating not only heats the desired ion-implanted region but also other parts, which has the adverse effect of deteriorating semiconductor characteristics.
Recently, methods of locally heating only desired regions have been studied, and a so-called laser annealing method in which laser light is irradiated has been attracting attention.

A crystal growth method in which polycrystals are made into single crystals by laser annealing has also been studied, and in this case, attention has been paid to the fact that crystal growth with fewer defects can be achieved by localized heating.

However, in such localized heating methods, it is preferable to increase the energy as much as possible and process the process in as short a time as possible from the viewpoint of defect-free crystal growth and improvement of device characteristics, since heat transfer to unnecessary parts is reduced. be.

(c) Purpose of the Invention Based on the above-mentioned purpose, the present invention proposes a beam irradiation device with high irradiation accuracy that can instantaneously apply strong energy.

(d) Structure of the invention The object is to provide an electron gun for preheating an irradiated object by irradiating the object with an electron beam, an electron beam control system for controlling the electron beam, and an electron beam control system containing these. a laser irradiation means for irradiating the irradiated object together with the electron beam through a transmission window with a laser beam focused from outside the column, and irradiates the same position of the irradiated object with the electron beam and the laser light at the same time. This can be achieved by using a composite beam irradiation device that has a function of heat-treating the object to be irradiated.

The present invention will be described in detail below with reference to the drawings.

(e) Embodiment of the Invention FIG. 1 is a cross-sectional structural diagram of an embodiment of a composite beam irradiation device according to the present invention. In the figure, a semiconductor wafer 1 as an object to be irradiated is placed on a stage 2 movable in the X direction and the Y direction, and the stage 2 is moved from the outside by a drive system 3. The interior of the column 5 is drawn into a high vacuum by the vacuum system 4, and a control device consisting of an electron gun 6 and an electromagnetic lens, slit, etc. that controls the electron beam 7 emitted from the electron gun 6 is placed vertically above the stage 2. system 8, which are similar to known exposure devices.

A laser introduction port 11 is provided in a concave shape on the side of the vacuum column 5 to allow the laser beam 10 from the laser light source 9 to enter therein, and a microscope introduction port 1 is provided on the other side of the column so that the irradiation position can be visually observed with an optical microscope.
2 is similarly provided in the shape of a recess. The reason why the laser beam 10 is irradiated at an angle from the side surface is that it is difficult to direct the electron beam 7 in terms of equipment.

Figure 2 is an enlarged partial cross-sectional view of the mixed irradiation area of the electron beam and laser light, showing the laser introduction port 1.
1 is also shown. At the laser introduction port, the laser beam 10 changes its irradiation direction with a reflection mirror 13, passes through a quartz window 14, and is focused by an objective lens 15. The narrowed laser beam passes through a protective glass 16 and enters a vacuum column 5. The electron beam enters the interior and irradiates the same position as the electron beam 7 at the same time.

The purpose of placing the reflecting mirror 13 and objective lens 15 outside the vacuum column 5 is that since they are insulators, they will charge up inside the vacuum column.
This is to prevent the beam, especially the electron beam, from being affected and the irradiation position to be distorted. The appropriate focal length f of the objective lens 15 is 50 to 70 mm; if it is shorter than that, a lot of evaporated matter from the semiconductor wafer 1 will adhere to it, making it impossible to keep the illuminance constant during processing, and if it is shorter than that, This makes it difficult to narrow down the laser beam. However, this evaporated material adheres to the protective glass 16 in front of the objective lens, and therefore the protective glass constantly needs to be replaced. Furthermore, since the protective glass is in a vacuum, it is preferable to sputter a thin metal film that transmits laser light onto the surface to prevent charge-up. Furthermore, the quartz window 14 is used to protect the objective range 15 and is sufficiently sealed, so that even if the protective glass 16 is replaced and the sealing is insufficient, the quartz window serves to compensate for this. On the other hand, the sealing glass 17 of the microscope introduction port 12 needs to be made of special glass to protect the viewer's eyes from the laser beam, and since this sealing glass 17 can be far away from the irradiation position of the semiconductor wafer 1, There will be less adhesion of objects.

What is particularly important about this device is that the electron beam is irradiated vertically, but the laser beam is irradiated obliquely, so it is better to irradiate the laser beam as close to vertical as possible. For example, if a scanning function is also provided in which the electron beam is deflected and irradiated, the distance between the objective lens of the laser beam and the irradiation position of the semiconductor wafer 1 is set to 50 to 70 mm.
If the scanning width is several centimeters, the centerline angle θ between the electron beam and the laser beam will be 25 to 30 degrees, as close as possible to the vertical line. Needless to say, the angle θ would be even smaller if no scanning function was provided. Further, it is preferable that the reflection angle at the reflection mirror 13 be as small as possible, and all of these problems regarding the direction of incidence are taken into consideration to prevent the intensity distribution of the irradiation spot from becoming non-uniform.

Incidentally, although the stage 2 is movable in the above explanation, the purpose of providing a scanning function to the electron beam is to achieve high-speed processing, and in that case, the reflection mirror 13 of the laser beam is It is necessary to add a mechanism to move them in synchronization so that both of them constantly irradiate the same position on the object to be irradiated. Furthermore, while stage movement is approximately 25 cm/sec, scanning speed is approximately 25 cm/sec.
It can be as fast as 5m/sec.

Here, the electron beam preheats (pre-anneals) the area to be heat treated, and by irradiating the preheated area to be heat treated with a laser beam, the present invention can instantaneously apply strong energy to the object to be processed. can be added to perform heat treatment in a short time.

Furthermore, although the irradiation positions of the electron beam and the laser beam must match, it is not necessary that the sizes of both irradiation spots be the same; for example, the electron beam irradiation spot can be set to 100 μmφ, and the laser beam irradiation spot can be set to 20 μmφ. It may be used as a diameter of ~30 μm.

Furthermore, unlike laser light, electron beams can heat a region of the desired depth on the surface of the object by adjusting the acceleration energy of the electrons. It also becomes possible to select the heat treatment area three-dimensionally.

(f) Effects of the Invention As described above, according to the present invention, unlike a laser beam, the output of an electron beam can be considerably increased by adjusting the current, so the beam diameter can be increased compared to a laser beam. This makes it possible to reliably preheat the entire laser beam irradiation area.

Further, the composite beam irradiation device according to the present invention includes:
Since the object to be irradiated is preheated by an electron beam and simultaneously irradiated with laser light, strong energy can be instantly applied to the object to be irradiated, allowing highly accurate local heating treatment that minimizes heat transfer to unnecessary parts. It can be carried out. Therefore, the present invention is useful for single crystal growth and annealing after ion implantation, and greatly contributes to the production of high-quality semiconductor devices, especially integrated circuits.

[Brief explanation of drawings]

FIG. 1 is a schematic cross-sectional view of a composite beam irradiation device according to the present invention, and FIG. 2 is a partially enlarged view thereof. In the figure, 1 is an irradiated object, 2 is a movable stage, 5 is a vacuum column, 6 is an electron gun, 7 is an electron beam, 8 is an electron beam control system, 9 is a laser light source, 10 is a laser beam, 13 is a reflecting mirror , 15 is an objective lens, 1
6 indicates a transmission window.

Claims (1)

[Claims] 1 An electron gun that irradiates an irradiated object with an electron beam to preheat the irradiated object, an electron beam control system that controls the electron beam, and a column containing these that transmits focused laser light from outside. A function of heat-treating the irradiated object by having a laser irradiation means for irradiating the irradiated object together with the electron beam through a window, and simultaneously irradiating the same position of the irradiated object with the electron beam and the laser light. A composite beam irradiation device characterized by having.