JPS6355775B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Technical Field of the Invention The present invention relates to antistatic technology when the surface of an insulator is irradiated with energy rays such as electron beams and ultraviolet rays.

(b) Technical Background and Problems In the manufacture of semiconductor devices, the surface of a semiconductor substrate is irradiated with an electron beam for purposes such as annealing an ion-implanted layer and heat treating an amorphous layer.

This is usually done by irradiating the entire surface of the substrate with an electron beam while moving the semiconductor substrate placed on an be irradiated with.

When an insulating film is irradiated with an electron beam, charge accumulates on its surface, and as this increases, the insulating film eventually undergoes dielectric breakdown. A similar situation occurs not only when irradiated with charged particle beams such as electron beams, but also when irradiated with radiation such as ultraviolet rays, as ejected electrons accumulate. This problem becomes particularly noticeable when using a powerful ultraviolet light source such as an excimer laser.

In the manufacturing process of semiconductor devices, an insulating film such as silicon dioxide is usually present on the surface of the substrate for the purpose of flattening the surface or preventing contamination. When irradiating, consideration must be given to dielectric breakdown.

A similar problem occurs with ion implantation, but in the case of ion implantation, positive charges are accumulated, and it is possible to neutralize the accumulated charges by using electronic shower or ultraviolet irradiation to generate negative charges. On the other hand, no suitable countermeasures against the accumulation of negative charges have been known so far.

(c) Object of the Invention In view of the above points, the present invention provides a method of irradiating energy rays while preventing negative charge build-up on an insulating film.

(d) Structure of the Invention In order to achieve the above object, the present invention involves irradiating energy rays that generate negative charges with the surface of an irradiated object, at least a part of which is an insulator, in contact with plasma gas. Features.

(e) Examples of the invention FIG. 1 shows an embodiment of the present invention.

Semiconductor substrate 2 placed on X-Y stage 1
(hereinafter referred to as wafer) is X
While moving in the direction and the Y direction, the entire surface is irradiated with the electron beam. 3 is an electron gun, and 4 is an electron lens for focusing the electron beam onto the wafer.

The above is the same as the conventional technology, but the apparatus used in the present invention is further provided with an electrode 5, and a high frequency electric field is applied between the electrode and the X-Y stage to apply it to the spatial region above the wafer. It is configured to generate plasma. The electrode 5 is provided with an opening 6 for passing the electron beam. In order to generate plasma, the space has an Ar gas atmosphere of 10 Torr, and the applied high frequency power of 13.56 MHz is about 100 W per wafer.
Furthermore, a DC voltage may be applied between the electrodes such that the electrode on the wafer side has a negative potential so that positive ions in the plasma efficiently reach the wafer surface.

When electron beam irradiation is performed while generating plasma under these conditions, the charges generated on the wafer surface are neutralized by the plasma ions, so they are not accumulated on the insulating film and are Therefore, no dielectric breakdown occurs.

Although the present invention is mainly applied to silicon wafers, under the above-mentioned conditions, silicon or silicon dioxide will not be strongly etched by the generated plasma gas, and will not pose an obstacle to device formation. Note that since the electrode 5 is newly provided and a voltage is applied, the voltage applied to the electron gun 3 or the focus condition of the electron lens 4 may need to be slightly modified.

The present invention can also be implemented as shown in FIG.

In this embodiment, a chamber 7 for plasma generation is provided separately from the electron beam irradiation space, and the generated plasma gas is transferred to the wafer 2.
reaches the surface of the insulating film and neutralizes the charges generated on the insulating film. The conditions for plasma generation are the same as those in the embodiment shown in FIG. 1, or slightly stronger.

If you use a device configured in this way, an extra electrode (corresponding to 5 in Figure 1) can be placed in the electron beam irradiation space.
Since there is no irradiation condition, the setting of irradiation conditions is not only the same as in the conventional method, but also etching and other adverse effects on the wafer can be reduced.

(f) Effects of the invention According to the method of the invention as explained above, the negative charges generated on the insulating film are successively neutralized.
No charge accumulation occurs, and dielectric breakdown can be prevented.

[Brief explanation of drawings]

1 and 2 are diagrams showing an embodiment of the present invention, in which 1 is an X-Y stage, 2 is a wafer, 3 is an electron gun, 4 is an electron lens, and 5 is for plasma generation. The electrode 7 is a chamber for plasma generation.

Claims (1)

[Claims] 1. A radiation irradiation that generates a negative charge on the surface of an insulator is characterized in that the surface of the irradiated object, at least a part of which is made of an insulator, is in contact with plasma gas. Energy ray irradiation method. 2. The energy ray irradiation method according to claim 1, wherein a space for generating the plasma gas is provided separately from a space for bringing the surface of the irradiated object into contact with the plasma gas.