JPH0456454B2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to an electron beam annealing device.
In particular, the present invention relates to an electron beam annealing apparatus having a function of correcting focal position deviation of an electron beam.

[Technical background of the invention and its problems]

In recent years, beam annealing has become popular, which uses energy beams such as electron beams and laser beams to heat-treat (anneal) semiconductor samples such as Si, Ge, Ga, and As, metal samples such as Al, Mo, and W, or metal compound samples. A device is being developed. By locally annealing a sample for a short period of time using this equipment, semiconductor devices can be made faster, more highly integrated, and more multifunctional, opening the possibility of realizing devices with new functions and new structures. It's coming.

FIG. 1 is a schematic configuration diagram showing a conventional electron beam annealing apparatus, in which 1 is a sample chamber, 2 is an optical barrel, 3 is an electron gun, 4 and 5 are lenses, 6 is a deflector,
7 indicates a sample, and 8 indicates a sample stage. In this device, an electron beam emitted from an electron gun 3 is focused by lenses 4 and 5, and the beam is scanned over a sample 7 by a deflector 6 to perform annealing of the sample 7, such as epitaxial growth or melt recrystallization. etc.

However, this type of device has the following problems. In other words, the temperature of the electron gun changes due to electron bombardment during annealing, and this change causes subtle changes in the dimensions between the cathode, grid, anode, etc., and the focal position of the electron beam shifts on the sample. The phenomenon described above occurs. When the focus position of the electron beam is shifted, the beam energy density during annealing becomes low, resulting in a situation such as insufficient annealing. For this reason, there was a risk that variations would occur in the characteristics of the sample after annealing.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide an electron beam annealing apparatus that can prevent focal position shift of an electron beam and improve uniformity and reproducibility of annealing.

[Summary of the invention]

The gist of the present invention is to detect the light emitted from the sample to be annealed during annealing, and to correct the focal position shift of the electron beam according to the intensity of this light, that is, to maximize the beam energy density.

When a sample to be annealed, such as Si, is irradiated with an electron beam and heated, the sample generates light based on bond vibrations specific to the constituent elements of the sample, in addition to light due to thermal radiation. The light based on this unique coupled vibration has a short wavelength and belongs to the shortest wavelength of the light generated by heating the sample, whereas the light due to thermal radiation has a long wavelength such as infrared or far infrared. This shortest wavelength component belongs to the visible to ultraviolet region and is clearly distinguished from light from thermal radiation in the infrared and far-infrared regions. The strength of this material changes rapidly depending on the sample temperature.

Therefore, when the focus position of the electron beam is aligned with the sample surface, the temperature of the sample surface is the highest, and as the focus position shifts, the temperature decreases. If the temperature is known and the lens system is controlled so that the intensity of the shortest wavelength component is maximized, it becomes possible to align the focal position of the electron beam with the sample surface.

The present invention focuses on these points, and uses an electron beam annealing apparatus that focuses an electron beam emitted from an electron gun onto the surface of a silicon sample to be annealed using a lens system, and anneals the sample. A photodetector section that detects the shortest wavelength component, and a detection signal from this photodetector section is input, and the lens system is feedback-controlled so that the intensity of the signal is maximized to adjust the beam energy density of the sample surface during beam irradiation. This paper proposes an electron beam annealing apparatus equipped with a control system that always maximizes the energy consumption.

〔Effect of the invention〕

According to the present invention, since the beam energy density is controlled by controlling the lens system so that the intensity of the shortest wavelength component of the photodetection signal is maximized, the surface of the sample to be annealed can be maintained at the highest temperature, and The annealing system can be improved. That is, the focal position of the electron beam can always be aligned with the sample surface. Therefore, annealing can be performed under the best conditions, and the uniformity and reproducibility of annealing can be improved. Therefore, when a semiconductor sample or the like is annealed, it is possible to prevent variations in the semiconductor characteristics after annealing, thereby contributing to improving the characteristics of devices formed on the sample. Furthermore, since feedback control is performed based on the shortest wavelength component that exhibits the largest amount of change with respect to temperature changes, the focal position of the beam can be corrected with good responsiveness.

[Embodiments of the invention]

FIG. 2 is a schematic configuration diagram showing an electron beam annealing apparatus according to an embodiment of the present invention. 11 in the diagram
1 is an evacuated sample chamber, and 12 is an electron optical column. A movable sample stage 13 is arranged in the sample chamber 11, and a sample 14 is placed on this stage 13.
is scheduled to be placed there. Inside the optical barrel 12, there is an electron gun 15 and a first lens 1 for beam focusing.
6, a second lens 17 and a scanning deflector 18 are respectively provided. The electron beam emitted from the electron gun 15 is focused by lenses 16 and 17 and scanned over the sample 14 by a deflector 18, thereby annealing the sample 14. Further, the electron gun 15 and lenses 16 and 17 are driven by power supplies 20, 21 and 22, respectively, which are controlled by a computer 19.

On the other hand, a light guide 23 is provided inside the sample chamber 11 to guide light emitted from the surface of the sample 14 to the outside of the sample chamber 11. The light guided from the light guide 23 passes through a filter 24 to a photodetector 25.
incident on . The filter 24 passes only wavelength components shorter than a predetermined wavelength, so that the photodetector 25 receives only the shortest wavelength component of the light emitted from the sample 14. The photodetector 25 is
For example, it is composed of a photodiode, and its detection signal is sent to the computer 1 via the A/D converter 26.
Sent on 9th. The computer 19 controls the lens power source 22 based on the input detection information so that the detection signal strength is maximized.

With such a configuration, the sample 14 annealed by electron beam irradiation generates light, and the shortest wavelength component of this light is detected by the photodetector 25. This detection signal is fed back to the lens power supply 22 by the computer 19, and the current flowing through the lens 17 is controlled so that the intensity of the detection signal is maximized. Thereby, the focal position of the electron beam is aligned with the surface of the sample 14. In other words, the electron beam is always focused on the surface of the sample 14 by a kind of feedback loop consisting of the lens 17, the sample 14, the photodetector 25, the computer 19, the lens power supply 22, etc. Therefore, annealing can be performed efficiently under the highest temperature conditions, and the uniformity and reproducibility of annealing can be improved.

An example in which this device is used to manufacture a MOS-LSI will be described below. FIGS. 3a to 3f are cross-sectional views showing the manufacturing process of the MOS-LSI. First, as shown in FIG. 3a, a SiO ₂ film 32 with a thickness of about 1 [μm] is deposited on a short crystal silicon substrate 31 having, for example, a P-type (100) plane.
is formed, and a SiN film 33 is formed thereon as necessary. This SiN film 33 is provided to facilitate single crystallization of a polycrystalline or amorphous silicon layer in a later step, and is not necessarily necessary. Next, as shown in FIG. 3b, for example, a film is deposited on the SiN film 33.
A polycrystalline silicon layer 34 with a thickness of 6000 [Å] is deposited, and an SiO ₂ film 35 with a thickness of about 2000 [Å] is formed thereon. Here, the SiO ₂ film 35 is for facilitating the single crystallization of a polycrystalline or amorphous silicon layer in a later step, and may be a SiN film.

Next, using the embodiment device shown in FIG. 2,
As shown in FIG. 3c, an electron beam is irradiated onto the sample to crystallize the silicon layer 34. At that time, the beam acceleration voltage was 10 [kV] and the beam current was 5 [mA].
And so. The width of the silicon layer 34 melted during annealing was about 50 [μm]. By repeating beam scanning, the crystal grains gradually decrease, and eventually the entire surface of the silicon layer becomes single crystallized. Here, in the example apparatus, feedback control is performed so that the focal position of the electron beam during annealing is always on the sample surface, so melting and recrystallization of silicon are extremely smooth, and heat treatment unevenness and untreated areas can be avoided. Alternatively, silicon single crystallization could be effectively carried out without any problems such as silicon evaporation.

Next, as shown in FIG. 3d, after removing the SiO ₂ film 35, the silicon layer made into a single crystal by beam annealing is patterned to form a second layer element forming region, and an insulating film for element isolation is formed using a well-known technique. 36
form. Subsequently, as shown in FIG. 3e, a polycrystalline silicon gate electrode 38 is formed on the silicon layer 34 via a gate oxide film 37, and a source electrode 38 is formed.
Drain regions 39 and 40 are formed to complete the MOS transistor. Next, as shown in FIG. 3f, after covering the entire surface with an insulating film 41, an Al wiring layer 42,
By forming 43 and 44, MOS-LSI
is completed.

Note that the present invention is not limited to the embodiments described above. For example, the lens system controlled by the feedback loop is not limited to the second lens, but may be the first lens or both the first and second lenses. Further, as a means for detecting the shortest wavelength component of the light emitted from the sample, a photodetector that detects only the light having the shortest wavelength may be used without using the filter. Furthermore, a photodetector that detects the signal intensity of each wavelength component in parallel may be used, and the one corresponding to the shortest wavelength component may be selected from each detection signal of this detector.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram showing a conventional electron beam annealing device, FIG. 2 is a schematic configuration diagram showing an embodiment of the present invention, and FIGS. It is a sectional view showing a manufacturing process. 11...Sample chamber, 12...Optical lens barrel, 13...
Sample stage, 14...sample, 15...electron gun,
16, 17... Beam focusing lens, 18... Scanning deflector, 19... Computer, 20, 21, 22
...Power source, 23...Light guide, 24...Filter, 25...Photodetector.

Claims (1)

[Claims] 1. An electron gun, a lens system that focuses the electron beam emitted from the electron gun onto the surface of the silicon sample to be annealed, a photodetector that detects the shortest wavelength component of the light emitted from the sample, and a photodetector that detects the shortest wavelength component of the light emitted from the sample. It is characterized by comprising a control system that inputs a detection signal and performs feedback control of the lens system so that the intensity of the signal is maximized so that the beam energy density on the sample surface is always maximized during beam irradiation. Electron beam annealing equipment.