JPS5984424A - Energy radiation equipment - Google Patents

Abstract

PURPOSE:To obtain an energy radiation equipment with side beam by a method wherein an obstacle potential point is provided at one point on a center axis of an electro-optical system and charged particle flux passing near the center is refracted outward and the charged particle beam is made to irradiate the target through a Quonset hut shape electron lens. CONSTITUTION:Charged particles radiated by a charged particle source 21 are squeezed by an electronic lens 22 and pass through a pinhole 23 and are radiated upon a specimen 25 such as a semiconductor substrate by an electronic lens 24. With this configuration, an obstacle potential point 26 is added between the lens 22 and the pinhole 23 and the charged particle passing near the needle tip 27 is bent outward and projects the shadow of the needle tip 27 enlarged downward. Moreover, a Quonset hut shape static lens is provided below the lens 24 and the charged particles are strongly squeezed to one direction to make ring shape beam form into linear distribution and into a trapezoidal distribution. With this configuration, the output power is not reduced and no thermal damage affects the substrate and the processing time is shortened by making the beam width wider.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to energy irradiation equipment, particularly equipment used for modifying surface layers by high-energy beam irradiation, and for electron beam annealing of polycrystalline and amorphous layers on the surface of semiconductor substrates. etc. is a dog.

Conventional configuration and its problems Electron beam irradiation equipment has traditionally been used for surface hardening and welding, and when applied to semiconductor devices, there are various problems in terms of ultra-precision such as submicron processing. .

The output energy distribution 1 from such an electron irradiation device has a Gaussian distribution as shown in Fig. 1 (2L), and the first
It is known that the peak at the center 2 is very high, as shown in the planar distribution diagram in Figure (b). For example, as shown in FIG.
A thin insulating film 12 with a thickness of about 0.0 m is formed. Recrystallization of the polycrystalline/recon layer 13 with a thickness of about 5 μm has a very large drawback. That is, the electron beam as shown in FIG. 1 has a high peak value and its energy reaches deeply into the substrate 11, creating thermal strain defects. If the peak value of the irradiated electron beam is lowered, the polycrystalline silicon layer 13 will not melt or the melting period will be very narrow, which is undesirable. Furthermore, when the entire surface is surface-treated, as shown in FIG. 3, even though the polycrystalline silicon layer 13 appears to be uniformly treated, when viewed in the depth direction, each electron beam 14 that has traveled It can be seen that the heat-treated portion 16 has a deep wavy shape corresponding to the peak, and is very uneven.

Purpose of the Invention The present invention efficiently realizes a wide and evenly distributed charged particle flux without reducing the output of the charged particle flux,
An object of the present invention is to provide an energy irradiation device using charged particles that can perform irradiation over a wide range without applying thermal strain deep into a substrate.

Structure of the Invention The present invention provides a faulty potential point, preferably a semicylindrical electron lens, in the middle of an electron optical system to lower the energy density in the central part of the charged particle flux and uniformize the energy distribution over a wide range. It irradiates the area.

DESCRIPTION OF EMBODIMENTS As shown in FIG. 4, charged particles emitted from a charged particle source 21 are focused by an electron lens 22,
The charged particle flux is then irradiated onto a sample 26 such as a semiconductor substrate by the next electron lens 24. By deflecting the electron lens 24, the charged particle flux is moved onto the sample 26. At this time, the energy distribution on the sample 25 has a Gaussian distribution as shown in FIG. 1, as is generally well known.

At this time, a fault potential point 26 is provided in the middle. This potential point 26 can be achieved by, for example, providing a small obstacle in the center of the beam.
Either support this with a thin insulator and charge it up.
Alternatively, it may be formed entirely of a conductor and charged in the same direction as the charged particle source 21, and the charged particles passing near the needle tip 27 are strongly repelled and bent outward. Note that charged particles passing far from the fault potential point 26 are not affected.

Therefore, the shadow of the needle tip 27 is enlarged and projected downward, and since charged particles are not absorbed by the needle tip 27, the output does not decrease. At this time, the resulting output energy distribution 31 on the sample surface 26 has the shape shown in FIG. 6(a), with the strongest portion 32 having a ring shape. That is, it can be seen that this beam has lower energy in the center compared to FIG. 1 and has a uniform energy distribution over a wide range. Next, if an electrostatic lens (cylindrical electron lens) 28 made of, for example, a parallel plate is inserted after the electron lens 24 as shown in FIG. The beam shape of τ is shown in Fig. 5(b).
As shown in FIG. 3, the distribution becomes elliptical and finally becomes linear 31'. Its output energy distribution is nearly trapezoidal, which serves the intended purpose, and is particularly effective in repeated pinch-shifted irradiation.

The effects of the present invention will be explained with reference to the results of application to a semiconductor element under very severe conditions.

As a sample, as shown in FIG.
A film in which a thick polycrystalline silicon film 13 was formed was used.

The conventional equipment is a refurbished low-pressure scanning electron microscope, and a 5K
V, 2mA can be taken out, and the scanning speed is set to 250.
It was fixed at mm,/sec. The output energy distribution obtained at this time has a Gaussian distribution as shown in FIG.

When the sample is fixed approximately 300 μm above the focal point position and the surface layer (silicon film 13) is melted, its width is approximately 7 μm.
Met. Next, while sending the beam horizontally by 3 μm,
After sequentially melting the entire surface of the sample, when the sample was broken, it did not break between the bones as usual, but in the shape of a shell. This indicates that it is undergoing large thermal strain. Furthermore, the fracture surface is polished diagonally,
When so-called tinting was performed, a non-uniform portion 16 as shown in FIG. 3 was observed.The deepest part of the portion 16 was about 1 μm.

Next, when an iron core supported by ceramic fibers was inserted as the fault potential point 26 shown in FIG. 4, the output energy distribution changed as shown in FIG. 5.

When a flat plate electrostatic field of 500V is applied, the beam becomes a linear beam as shown in Figure 6, and the trapezoidal energy distribution becomes
observed on the sample surface.

When these beams were scanned over the sample surface under the above-mentioned conditions, the diameter during melting was approximately 25 μm, which was more than three times as large. In addition, it was found that interosseous spaces were also formed, indicating that thermal strain did not reach the substrate.

Because the melting area is wide, the horizontal feed is about 20
Even though it was as large as μm, the polycrystalline silicon on the sample surface was completely melted, and the uniformity was improved.

Effects of the Invention As is clear from the above description, the present invention provides an energy irradiation device with a wide beam width that does not cause a decrease in output energy and does not cause thermal damage to the substrate. Since the beam width is wide, the scanning width in the horizontal direction can be widened, and therefore the processing time is shortened.
It also has the advantage of improving surface accuracy. It is clear that the present invention is applicable not only to silicon but also to all surface treatments, and is also applicable not only to electron beams but also to charged particles.

[Brief explanation of drawings]

Figure 1 1&), +1)) is a frontal distribution diagram and a plane distribution diagram of the conventional output energy distribution, Figure 2 is a cross-sectional structural diagram of the sample,
FIG. 3 is a cross-sectional view showing uneven heat treatment of a sample cross section obtained as a result of conventional energy irradiation, FIG. 4 is a schematic configuration diagram of an energy irradiation device according to an embodiment of the present invention, and FIG. 6(a) ,
(b) is a front distribution diagram and a plane distribution diagram of the output energy distribution obtained by the present invention, and FIG. 6 (IL) is a front distribution diagram and a plane distribution diagram of another energy distribution of the present invention. 21...Charged particle source, 22.24...
Electron lens, 25... Sample, 26...
Fault potential point, 28...Horse-shaped electron lens,
31.31'・Old・・Energy distribution. Name of agent: Patent attorney Toshio Nakao and one other person
1 Figure ((L)' 2 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6

Claims (2)

[Claims] (1) A fault potential point is provided at one point on the central axis of the electron optical system path,
An energy irradiation device characterized by irradiating a target object with a charged particle beam by bending a charged particle bundle passing near the central axis outward. (2) A fault potential point is provided at one point on the central axis of the electron optical system path,
By bending the charged particle flux passing near the central axis outward and passing it through a semicylindrical electron lens,
An energy irradiation device characterized by irradiating a target object with a charged particle beam having an energy distribution compressed in one direction into an oval shape.