JPH01103824A - Laser annealing process - Google Patents

Abstract

PURPOSE:To facilitate the single-crystallization by a method wherein an element is scanned by multiple energy beams so that the energy intensity in the central part of irradiating region by the energy beams may be lower than that in the outer parts. CONSTITUTION:Multiple energy beams are applied to the irradiating region 1 of energy beams with the energy intensity distributed as shown in figure to start setting process from the central part. For example, an element is irradi ated with three concentrated reference beams to be scanned likewise for setting from the central scanning line enabling the setting at both ends to be delayed. When scanned in the arrow direction, the preceding beams 10A located on the central scanning line melt down or preheat the central part while the laser beams 10B, 10C symmetrically located behind on both sides of the central scan ning line melt down the both ends at a time lag. If the element is scanned by such beams, the element is set from the central scanning line toward both sides to be easily single-crystallized while enabling the scanning width to be widened to 100-150mum.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for improving laser annealing in which polycrystalline grains are coarsened by a laser beam to form a single crystal.

Laser light is widely used in optical communication and inspection equipment such as length measuring machines, and processing machines such as bath welding and cutting, as well as surgical scalpels, have also been developed using the energy of laser light. There is. When manufacturing semiconductor devices, the energy of laser light is used for annealing to remove the strain that occurs in the semiconductor substrate crystal after impurity ions are implanted. A method has also been proposed in which a polycrystalline material deposited on a substrate is made into a single crystal by laser annealing.

[Conventional technology]

The present invention proposes a practical improvement to the latter of such laser annealing methods, that is, a method for converting polycrystalline materials into single crystals.

As is well known, laser light is emitted from a laser oscillator,
The laser beam is narrowed down by a lens system to become a laser beam with a diameter of several tens of micrometers, and is irradiated onto the sample.The entire sample is scanned, and the irradiation energy melts the polycrystal, solidifies it, and turns it into a single crystal. However, the energy distribution of the beam is generally a Gaussian distribution, with the energy being strong at the center of a circular beam and decreasing as the distance from the center increases.

[Problem to be solved by the invention]

When such a standard laser beam is irradiated and scanned, the beam solidifies and crystallizes from the periphery toward the center, causing the grain boundaries to interfere with each other, causing the crystal to expand and form a single crystal. It is extremely difficult to prevent crystallization and convert it into single crystals.

An object of the present invention is to solve these problems and easily expand the crystal to form a single crystal.

[Means to solve the problem]

The problem is that when a non-single-crystal semiconductor layer is irradiated with an energy beam and scanned to form a single crystal, multiple beams are applied so that the energy intensity at the center of the irradiation area of the energy beam is smaller than the energy intensity at the outside. The problem is solved by a laser annealing method characterized in that the scanning is performed with a beam of energy.

[Effect]

As mentioned above, by combining and irradiating multiple energy beams, the central part of the beam scanning line solidifies quickly.
Since both end portions are solidified slowly, grain boundaries do not interfere with each other, and a wide range of regions can be easily formed into single crystals.

〔Example〕

An embodiment of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a diagram showing the energy intensity distribution in one embodiment of the present invention. In this embodiment, a plurality of energy beams are used so that the energy intensity distribution of the energy beam irradiation area 1 is as shown in FIG. 1, and solidification starts from the center.

For example, three standard laser beams (standard means a general beam with Gaussian energy distribution) are irradiated with a collective laser beam and scanned, similarly solidifying the center of the scanning line quickly, and solidifying the center of the scanning line quickly, and It is possible to slow down solidification. Figure 2 shows the irradiation shape of such a laser beam.If the laser beam is scanned in the direction of the arrow, the 10 leading beams located at the center of the scanning line will melt or preheat the central part, and then the laser beam at the center of the scanning line will melt or preheat. Laser beam I placed symmetrically on both sides
OB and IOC melt on both sides with a time delay.

The scanning speed is, for example, 10 cM/sec, the total beam energy is about 10 to 15 watts, and the sample is a semiconductor substrate heated to 500°C. If you scan with such a beam,
Since it solidifies from the center of the scanning line toward both sides, it is easy to form a single crystal, and the width becomes 100 to 150 μm during the scanning.

〔effect〕

As described above, the present invention is a method of promoting single crystallization by solidifying from the center of the laser beam scanning line. The invention facilitates single crystallization, contributes to miniaturization and precision of semiconductor devices, and is useful for improving characteristics.

[Brief explanation of the drawing]

Figure 1 is an energy model diagram of the irradiation area in one embodiment applied to the laser annealing method according to the present invention, and Figure 2 is an energy model diagram of the irradiation area.
It is a figure showing the irradiation shape of the energy beam of the book. In the figure, 1 indicates the energy intensity of the energy irradiation area of the laser beam, and 10A to IOC indicate the energy beams, respectively. ml:-7).悌11E3 Judgment 2 Punishment

Claims (2)

[Claims] (1) When irradiating and scanning a non-single-crystal semiconductor layer with an energy beam to form a single crystal, multiple rays are A laser annealing method characterized in that the scanning is performed with an energy beam. (2) The plurality of energy beams are composed of first, second, and third energy beams, of which the first energy beam is located at the center of the scanning line, and the second,
2. The laser annealing method according to claim 1, wherein the three energy beams are positioned on both sides of the scanning line of the first energy beam and are scanned later than the first energy beam.