JPS5952831A - Beam annealing method - Google Patents

Abstract

PURPOSE:To increase speed, and to obtain arbitrary shape and intensity distribution by overlapping a plurality of beams emitted from a plurality of beams generating means on a substrate through a total reflection mirror forming a paraboloid and irradiating the beams in an arcuate shape. CONSTITUTION:Laser beams 5 from a plurality of lasers 4 are irradiated to a parablolidal mirror 6 so as to be overlapped at every half, the reflected beams 7 are focussed on a polysilicon film 3, an arcuate image, beam size thereof is 10mu in the X direction 7a and 2mm. in the Y direction 7b, is formed, and the substrate 1 is scanned at 5cm/sec in the projecting direction, thus growing 1cm single crystalline width in the rear section of a recessed section. The intensity distribution 8 of laser beams takes a trapezoid along an arc. Accordingly, a large number of energy beams are radiated simultaneously in multiple-beam annealing and overlapped by a reflecting mirror, thus arbitrarily obtaining beam shape and intensity distribution.

Description

Detailed Description of the Invention (a) Technical Field of the Invention This invention relates to light annealing for monocrystallizing a polycrystalline silicon layer on an insulating film formed on a substrate using a light beam, such as a laser beam, and is particularly advantageous for high-speed processing. Regarding the annealing process.

(bl Technology background) The so-called 5OI (Sil 1 conon
Polycrystalline silicon (poly-crystalline silicon), which has excellent electrical properties, is attracting attention.
A method of forming an active element by single crystallizing alSilicon (polysilicon) has been put into practical use.

Polycrystalline silicon (hereinafter referred to as polysilicon), which is mainly obtained by vapor phase growth using hydrogen reduction or thermal decomposition, consists of small single crystals arranged irregularly, so they can be replaced with regular single crystals by annealing. A scanning method using continuous wave mode argon ion laser light is generally used.

(C) Conventional technology and problems Scanning with C'1NAr+ laser light is most suitable for single crystallization of polysilicon, but the maximum laser power is about 20W and the beam size needs to be reduced to 10oμψ, so the processing capacity is low. low.

On the other hand, as the degree of integration increases with the progress of microfabrication technology, the polysilicon area also tends to increase, necessitating a faster annealing process. For this reason, increasing the size of the laser device not only increases the cost but also increases the power density, which destroys the polysilicon layer and damages the substrate due to thermal energy. In order to perform uniform laser annealing, at least the spatial mode must be a single mode (with a Gaussian intensity distribution) or a mode close to it. It is necessary to convert it to a distribution.

(d) Purpose of the Invention In view of the above points, the present invention provides multi-beam annealing that simultaneously irradiates a plurality of laser beams onto an integrated circuit board in a superimposed manner to reduce speed and obtain an arbitrary shape and intensity distribution. With the goal.

(e) Structure of the Invention In order to achieve the above object, the present invention provides a plurality of light beam generating means in light annealing in which a non-crystalline semiconductor layer on an insulating film formed on an integrated circuit board is irradiated with a light beam to form a single crystal. This is achieved by irradiating a plurality of light beams emitted from the substrate through a total reflection mirror having a parabolic surface in an overlapping arc shape onto the substrate.

(f+ Example of invention Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a cross-sectional view showing a polysilicon layer formed on an integrated circuit substrate. CVI by CVD method on the substrate]
- A 5102 film is formed by a SiO2 film or a high temperature heating method, and a polysilicon film 3 is formed on the insulating film 2 by a hydrogen reduction method or a vapor phase growth method using a thermal decomposition method to form a polysilicon region. .

An annealing process is performed to make this polysilicon region into a single crystal.

FIG. 2 is a block diagram showing an embodiment using light beam annealing of the present invention.

In the example, the output is 20W, and the beam size is 201+IIIψ.
Ten C-WAγ lasers 4 are arranged at equal intervals with good alignment, and a total reflection type parabolic mirror 6 is installed in the radiation traveling direction of the laser beam 5.

The laser beam 5 from the laser 4 irradiates the parabolic mirror 6 so as to overlap by A, and the reflected light 7 is focused on the polysilicon film 3 as shown in the figure, and the beam size is X.
When an arcuate image of 10μ in the direction 7a and 2III+11 in the Y-direction nozzle b was created and the substrate 1 was scanned in the convex direction at 5''see, a single crystal width 14 was grown behind the concave portion.

The intensity distribution 8 of the laser beam is distributed along an arc as shown in the figure. In multi-beam annealing configured in this way, there is an advantage that the beam shape and intensity distribution can be determined arbitrarily by emitting a large number of energy rays simultaneously and overlapping them with a reflecting mirror.

That is, by selectively combining the output beam size of the laser and the shape of the reflecting mirror under conditions suitable for the annealed sample, it becomes possible to produce a single crystal of high quality at a higher speed than in the past.

(g) Effects of the Invention As explained in detail above, the multi-beam annealing of the present invention improves processing capacity and high speed compared to the conventional method, and also provides high-quality single beams with arbitrary beam shapes and intensity distributions. It has excellent effects such as enabling crystallization.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view showing a polysilicon layer formed on an integrated circuit substrate, and FIG. 2 is a configuration diagram showing an embodiment using multi-beam annealing of the present invention. In the figure, 1... integrated circuit board, 2 insulating film, 3... polysilicon film, 4. ,,,,
CWAγ laser, 5 - Laser beam, 6 - Parabolic mirror, 7 Reflected light, 8 - Intensity distribution.

Claims (1)

[Claims] In light beam annealing, in which a non-single crystal semiconductor layer on an insulating film formed on an integrated circuit board is irradiated with a light beam to form a single crystal, a plurality of light beams emitted from a plurality of light beam generating means are totally reflected in a parabolic surface. A light annealing method characterized by irradiating the substrate in an overlapping arc shape through a mirror.