JPH0249533B2 - KADENBIIMUSOCHI - Google Patents

Description

[Detailed Description of the Invention] [Technical Field] The present invention is for use in so-called SOI manufacturing technology, etc., which improves the quality of semiconductor films made of silicon or the like deposited on insulating films in electronic devices. The present invention relates to a charged beam device that scans a sample surface with a linear charged beam, and in particular is capable of controlling the current density distribution of the linear charged beam with high precision.

[Prior Art] Conventionally, a laser annealing device has been used as one of the beam devices for producing SOI films, but this conventional device has the problem that the annealing conditions vary depending on the reflectance of the sample surface due to light, etc. It had been pointed out. In order to solve this problem, an electron beam annealing apparatus as shown in FIG. 1 has been developed. The illustrated electron beam annealing apparatus scans a sample surface with a spot beam formed using a magnetic field lens. 1 is an electron gun, 2 and 3 are magnetic field lenses, 4 is an electron beam deflector, and 5 is a sample. In such a conventional electron beam annealing apparatus, an electron beam from an electron gun 1 is focused onto the surface of a sample 5 by magnetic field lenses 2 and 3, and is scanned at high speed in the X-axis direction by a deflector 4. The crystallization of the semiconductor film, which is the sample, is controlled by scanning at low speed in the axial direction. Conventional apparatuses having such a configuration have the disadvantage that it is difficult to optimize the scanning conditions of the spot beam, and it is difficult to perform sufficient crystallization over a wide area. In addition, the electron beam from the electron gun 1 is made into a line using a linear filament, etc., and the linear electron beam is imaged onto the surface of the sample 5 by magnetic field lenses 2 and 3, and scanned in one direction by a deflector 4. Even when operated in such a way, the current density distribution of the linear electron beam cannot be controlled, which limits the area and shape that can be crystallized.

Generally, for laser annealing equipment, 1/4
The effectiveness of an annealing device that uses a laser beam with a bimodal energy distribution obtained by splitting the laser beam using a wavelength plate and a birefringent plate and combining the two beams has been pointed out. Since the light absorption characteristics of the sample surface are unique to the irradiated substance, it has been difficult to control the energy supplied to the irradiation laser beam in accordance with the light absorption characteristics of the sample surface. On the other hand, in electron beam annealing equipment, it is difficult to form a linear electron beam with a double bee-like energy distribution even if a linear electron beam source is used, and in spot beam scanning, the electron beam scanning signal is Attempts have been made to control the waveform to create an equivalent double bee-like energy distribution, but this was insufficient to control the annealing conditions with high precision, and there were also difficulties in terms of efficiency.

[Summary of the Invention] An object of the present invention is to eliminate the above-mentioned conventional drawbacks, change the current density distribution on a linear charged beam by utilizing a unique lens effect in electro-optics, and create a bimodal energy distribution. An object of the present invention is to provide a charged beam device that forms a linear charged beam having a desired energy distribution on a sample surface and enables highly accurate control.

That is, the charged beam device of the present invention includes a charged beam generation source, a charged particle beam lens consisting of a combination of at least one set of multipoles and an aperture electrode, or a combination of two or more sets of multipoles, and has at least one location. In addition to having a point with high current density,
This method is characterized by forming a linear charged beam whose point position and current density can be controlled. Note that in this specification, a quadrupole, a hexapole, an octupole, etc. are referred to as a multipole.

[Examples] The present invention will be explained in detail by way of examples with reference to the following drawings.

First, as an example of the charged beam device of the present invention, an example of the configuration of an electron beam annealing device is shown in FIG. In the illustrated configuration, 1 is an electron gun, 2 is a lens system consisting of a combination of two electric field type quadrupoles and a closed electrode for forming a linear electron beam having a bimodal energy distribution, Among them, 21 and 22 are quadrupoles, respectively, and 23 and 24
is an aperture electrode for exciting these and the quadrupole elements 21 and 22, respectively, to perform an octupole lens action. 3 is a magnetic field lens for projecting and focusing the linear electron beam formed by the lens system 2 onto the surface of the sample 5; 4 is a magnetic field lens for deflecting the linear electron beam to an arbitrary position on the surface of the sample 5; 5 is a sample to be annealed.

Generally, it is not possible to form a linear electron beam having a bimodal energy distribution using only a magnetic field lens used in an electron beam device.
For example, by changing the grid bias by using a linear cathode in the electron gun, or by distorting the cross-sectional shape of the electron beam using a stigmator for astigmatism correction, it is possible to obtain a bimodal shape. It is difficult to shape or control the current density distribution.

On the other hand, in the configuration example shown in the second figure, instead of forming a linear electron beam by utilizing the axial anisotropy of the quadrupole lens system, an aperture electrode is used together, or the octupole lens itself is used. The aperture aberration in the X and Y directions can be arbitrarily controlled by the action of the octupole lens used, and as a result, a linear electron beam with a bimodal energy density distribution is formed. , it is also possible to control the distance between two points having a bimodal shape and high energy density and the entire length of the linear beam.

To explain in more detail the operation of the apparatus of the present invention having such advantages, when it is necessary to increase the utilization efficiency of the electron beam from the electron beam generation source, such as in an electron beam annealing apparatus, the electron beam current is used. Limited by the characteristics of the electron lens system. Therefore, the characteristics of an electronic lens system are determined by focal characteristics and aberrations, especially aperture aberrations. In other words, in a quadrupole lens system, if the beam aperture angle in the XZ plane, that is, the corner aperture angle is α, and the aperture angle in the YZ plane is β, then the electron beam spreads ΔX and ΔY due to aperture aberration in the X and Y directions are are expressed as the following equations (1) and (2), respectively.

ΔX＝C _A30 α ³ +C _A12 αβ ² (1) ΔY＝C _A21 α ² β＋C _A03 β ³ (2) Here, C _A30 , C _A12 , C _A21 , C _A03 are the spherical surfaces of spherical lenses such as magnetic field lenses. This is an aperture aberration coefficient corresponding to an aberration coefficient.

Generally, when a linear electron beam is formed using a quadrupole lens system, if the aperture aberration coefficient is 0, the electron beam from the point electron source will become a linear electron beam as shown in Figure 3a. becomes. However, in reality, since the electron source has a finite size, the electron source will be focused to a size multiplied by the lens magnification in the X direction and the Y direction in the quadrupole lens system. Therefore, in a two-stage electric field type quadrupole lens system as shown in Fig. 2,
Regarding the XZ plane, it receives a diverging-converging lens action,
In addition, regarding the YZ plane, when a linear electron beam is formed by exciting a quadrupole so as to undergo a converging-diverging lens action, both the aperture aberration coefficients C _A03 and C _A21 often take positive values, If the spread of the beam due to aperture aberration is exaggerated, the electron beam will have a cross-sectional shape as shown in FIG. 3b. Generally, in a multi-stage quadrupole lens system, the aperture aberration coefficient C _A30 , which is proportional to the cube of the aperture angle in the direction in which the beam trajectory value increases, is larger than other aperture aberration coefficients, but the aperture aberration coefficient C _A12 , C _A21 and C _A03 are comparable to or less than the spherical aberration coefficient of the magnetic field lens. Therefore, the change in line width of a linear electron beam within a practical electron beam aperture angle is small.

Based on the above, the aperture aberration coefficient C _A21 can be made negative by using the aperture electrodes 23 and 24 arranged close to the quadrupoles 21 and 22, respectively, or by using the octupole itself as in the configuration example shown in the second figure. If _the octupole lens effect is induced to take the value of Changes as shown in .

Here, assuming that the current distribution of the electron beam incident on the quadrupole lens system is uniform and the beam current density is as shown in Figure 4a when aperture aberration is not controlled, then the above As is clear from the explanation, by adjusting the octupole lens action so that each aberration coefficient takes an appropriate value, and by focusing the beam as shown in Fig. 3d, the beam can be focused as shown in Fig. 4b. A beam current density distribution can be created. Here, the distance l between two points with high current density in Figure 4b can be controlled by the excitation intensity of the aperture electrode or octupole, and the length L of the linear beam controls the excitation intensity of the quadrupole. The characteristic length is that each can be adjusted almost independently by adjusting the length.

Note that in the configuration example shown in the second figure, the electron gun 1
The use of a linear cathode is extremely effective in increasing the efficiency of annealing and the like. Moreover, the quadrupole lens system for linear beam formation can also be configured in three stages. Furthermore, in order to obtain a bimodal beam current density distribution, as mentioned above, basically the aperture aberration coefficient C _A03 is increased to some extent, and the aperture aberration coefficient C _A21 is made to take a negative value. Based on equation 2), the excitation intensity of the aperture electrodes 23, 24 or the octupole is adjusted so that the beam spread due to aperture aberration becomes as shown in Figure 3d. By also controlling the aperture aberration coefficient, it is possible to achieve even higher quality electron beam focusing.

Further, multipoles such as quadrupole and octupole used in the charged beam device according to the present invention can be handled in the same way regardless of whether they are electric field type or magnetic field type, although there are differences in aberration coefficient changes with respect to lens excitation intensity.

In the above explanation, we have discussed the case where the current density distribution of the electron beam incident on the quadrupole lens system is uniform as shown in Figure 4a, but the total energy incident within the line width of the linear electron beam is When controlling the density distribution to have a bimodal shape as shown in Fig. 4b, the electron beam generation source may be changed to form a hollow beam, or the configuration example shown in Fig. 2 may be controlled to form a hollow beam. It is clear that a desired density distribution can be easily achieved by providing a diaphragm means for controlling the line width direction or the line length direction on the beam incidence side or the beam exit side of the lens system 2.

In addition, in the charged beam device according to the present invention, the density distribution control of the linear beam can be performed not only for the electron beam described above but also for the ion beam in the same manner as described above. For example, the second
If the electron gun 1 in the illustrated configuration example is replaced with an ion source and the magnetic field lens 3 is replaced with a unipotential lens or quadrupole lens as an electric field type lens, the ion beam can be controlled in the same way as the electron beam. can.

[Effects] As is clear from the above description, according to the present invention, a linear charged beam having an energy density distribution that cannot be realized with a lens system normally used in a charged beam device can be formed. Therefore, it can be applied to the production of high-quality crystalline thin films, etc., and can bring about remarkable effects.

[Brief explanation of drawings]

FIG. 1 is a diagram showing a schematic configuration of a conventional electron beam annealing device, FIG. 2 is a diagram showing an example of a schematic configuration of a charged beam device of the present invention, and FIGS. 3a to 3b are diagrams showing aperture aberrations in focused charged beam FIGS. 4A and 4B are characteristic curve diagrams respectively showing aspects of the beam current density distribution according to the conventional method and the present invention. FIGS. 1... Electron gun, 2, 3... Lens system, 4... Deflector, 5... Sample, 21, 22... Quadrupole winding,
23, 24...Aperture electrode.

Claims (1)

[Claims] 1. In a charged beam device having a charged beam generation source and a charged particle lens consisting of a combination of at least one set of multipoles and an aperture electrode, or a combination of two or more sets of multipoles, the excitation voltage of the charged particle lens or By controlling the current, a linear beam is generated after passing through the charged particle lens, and at the same time, the current distribution on the linear beam is changed, and at least one spot on the sample surface is irradiated with the linear beam. giving rise to high points in the current distribution,
A charged beam device characterized in that it is configured to control the position of a high point of the current distribution and the current density.