JPS60152618A - Device for performing heat treatment of material by electron beam - Google Patents

Abstract

PURPOSE:To provide a titled device which can heat-treat efficiently and uniformly a material having a relatively large surface area by providing a mechanism which increases the deflecting angle of an electron beam and decreases the scanning speed of the beam. CONSTITUTION:A beam deflecting system deflects the electron beam 2 which has a linear section and passes the orbit 4 while said beam is not deflected, by using a deflecting coil 3 in the stage of scanning the surface of a semiconductor wafer 1 with said beam 2 and annealing the surface. The deflecting coil for deflection in a direction Y is separately provided (not shown in figure). The trace 5 of the electron beam irradiation after the beam 2 is deflected and scanned in the direction X is annealed into a belt shape. If reference saw-tooth wave current 21 is passed to the coil 3, the scanning speed of the beam on the wafer 1 is approximately constant or slightly increases in the peripheral part where the angle of deflection is large. If the deflecting coil current of a synthesized wave 32 superposed with sinusoidal current waveform 31 for correction is thereupon used, the change rate of the current hence the scanning speed are maximized at the deflection center 33 in the direction X and the current change rate (approximately proportional to the scanning speed) is smaller the nearer the peripheral parts 34, 35.

Description

[Detailed Description of the Invention] This invention scans an electron beam, especially an electron beam with a linear cross section, to perform total heat treatment (hardening, crystallization, annealing, etc.) of the surface layer of materials such as dielectrics, semiconductors, and gold maple bodies. The present invention relates to an electron beam device.

An example of an electron beam device that uses an electron beam with a linear cross section to anneal a semiconductor is described. In this example, a linear beam with a uniform distribution of several lengths is scanned over the material to uniformly anneal a strip of several widths. Processing can be performed by circular eclipse, which is more advantageous than using an electron beam with a point-shaped cross section in terms of processing speed and uniformity.

However, when using an electron beam with a linear cross section, a relatively large □ beam current is required, so the cross-sectional dimension of the electron beam in the electron beam path generally becomes large (thick), and the beam deflection that scans this The electric field of the system
As for fc, the deflection convergence due to the magnetic field tends to increase. The electron beam at the deflected position (near the periphery) is a little blurred compared to the electron beam at the non-deflected position (center) on the material, and if the beam current density is low, the processing may be insufficient. In this case, the degree of annealing becomes uneven between the center and the periphery of the material.

One way to achieve uniform annealing in such cases is to change the electron lens action of the beam focusing system by changing the deflection angle (electron beam irradiation position on the material). In some cases, it is difficult to achieve optical uniformity because deflection aberration cannot be canceled out, or when a magnetic lens is used, rotation of the cross section of the electron beam occurs in the direction of the beam.

In order to eliminate these drawbacks, the present invention provides a device*1 for slowing down the electron beam deflection angle and beam speed IF, and will be described in detail below with reference to the drawings.

FIG. 1 shows an example in which the surface of a semiconductor wafer 1 is annealed by scanning it with an electron beam 2 having a linear cross section.

The beam deflection system uses 3t deflection coils and is 4 in the figure when no deflection is used.
The electron beam that passes through the entire orbit is deflected in the X direction in the figure. A deflection coil that deflects in the Y direction in the figure is provided separately (not shown).
. The electron beam irradiation trace 5 deflected and scanned in the electron beam 2t-X direction is annealed in a band shape.

When the reference sawtooth current 21 shown in the waveform diagram of FIG. 2 is applied to the deflection coil 3 shown in FIG. Increases slightly. Therefore, Fig. 3 (modified sine for the sleeve of at)
Lt/rt, box-shaped Wlj are superimposed, and the same figure (bl composite wave 3
When a deflection coil current of 2 is used, the rate of change of this current, and therefore the scanning speed, is maximum at the deflection center 33 in the X direction, and the closer to the periphery 34, 35 the smaller the rate of current change (proportional to the scanning speed) becomes. . In one embodiment of the present invention, this waveform 3
A current of 2 is applied to the deflection coil shown in FIG. 1, and as the deflection angle in the X direction increases, the scanning speed is decreased overall.

When a constant current is applied to the Y-direction deflection coil on the wafer l in FIG. 1 to anneal the band region 6, the scanning speed is reduced according to the Y-direction deflection angle, so the waveform 22 in FIG. A reference sawtooth waveform with a gentle slope is generated, and a composite wave with a correction waveform is generated in the same manner and used as the current waveform of the X-direction deflection coil 3.

It should be noted that although it is a matter of theory that flowing a composite wave current through the deflection coil 3 can be easily implemented using general electric circuit technology, it is possible to use a correction deflection coil separate from the correction waveform current or voltage total deflection coil 3. Alternatively, it may be configured to be supplied to an electrostatic deflection electrode. In the embodiment shown in FIG. 1, the wafer l is annealed when the electron beam 2 is scanned from left to right in the figure, and the electron beam 2 is returned to its original position in a sufficiently short time (retrace period) on the way back. In this way, the 7 Neil effect during the retrace period can be ignored. 23 in the waveform diagrams in Figures 2 and 3.
．． 24.36 indicates the retrace period.

Next, the same process is performed with a slight shift in the Y direction, and the entire required area of the next area is processed.

Instead of forming the deflection coil current waveform and the deflection electromagnetic field by combining the sawtooth wave and the correction waveform, it is also possible to use a mechanism such as creating a command waveform on a computer and then applying the desired current waveform to the deflection coil. good. Of course, electronic lens correction or the like may be used together with these deflection corrections.

As explained in the above embodiments, the apparatus of the present invention, in which the scanning speed of the electron beam is decreased as the deflection angle increases, uses an electron beam with a linear cross section, and the occurrence of deflection aberration (blur) in the case of -fc. Despite this, it is possible to eliminate the phenomenon of deterioration in the degree of heat treatment at the periphery where the deflection angle is large, and it is possible to efficiently and uniformly heat treat materials with a relatively large surface area.
Great practical effects can be obtained.

[Brief explanation of the drawing]

5- Fig. 1 is a perspective view of the vicinity of the material to be processed (semiconductor wafer) in an embodiment of the apparatus of the present invention, and Figs. 2 and 3 (al.
, (bl is an example of the waveform of the deflection coil current. l... Semiconductor wafer, 2... Electron beam, 3... Deflection coil, 5... Group electron Beam irradiation trace, 21°22...Reference sawtooth wave current waveform, 31...Sine wave current waveform for correction, 32...
...Deflection coil current waveform (composite wave). 6-

Claims (1)

[Claims] 1. An apparatus for heat-treating materials by means of an electron beam, characterized in that it is equipped with a mechanism for slowing down the rate of the electron beam O while increasing the angle at which the electron beam is inclined.