JPS6323312A - Annealing device by light beam - Google Patents

Abstract

PURPOSE:To achieve the annealing treatment of a single crystal over a wide area by a device wherein two homogenizers for formation of crescent-shaped beam spots or two reflecting plates are arranged face to face with each other and the shape of the crescent-shaped beam spots can be reversed so that the single crystal can be annealed by the beam spots of two different shapes after the forward and backward movements of the X-Y stage. CONSTITUTION:Two homogenizers are so arranged face to face with each other that the shape of each crescent-shaped beam spot can be reversed. When a homogenizer 11b is used at the scanning operation in the x direction (going direction), a light beam 13 is irradiated into the homogenizer 11b after reflection at a mirror 12b which changes the direction of the light beam 13. At the scanning operation in the returning direction (-x direction), the mirror 12b is retracted from the light path so that the light beam 13 can be irradiated into a homogenizer 11a after the direction of the light beam is changed after reflection at a mirror 12a destined for the homogenizer 11a. As an alternative system, a mirror 12c can be so arranged that it can be moved in the right and left directions. When the homogenizer 11a is used, the mirror 12c is moved to the position above the homogenizer 11a. When the homogenizer 11b is used, the mirror 12c can be moved to the position above the homogenizer 11b.

Description

[Detailed Description of the Invention] [Summary] Two crescent beam spot forming homogenizers or reflectors are arranged facing each other so that single crystal annealing can be performed at both crescent beam spots on the way to and from the x-Y stage. This is a device that changes the direction of the crescent beam spot.

[Industrial application field]

The present invention relates to a light beam annealing device, and more specifically, the present invention relates to a light beam annealing device, and more specifically, a pair of means for forming a crescent beam spot is arranged opposite to each other, and the traveling path of a linear laser beam is changed, or the pair of means The present invention relates to a device that can perform annealing on the forward and backward movement of an X-Y stage (or on the forward and backward movement of a laser beam when scanning a laser beam) by changing the direction of the X-Y stage.

[Conventional technology]

For example, silicon-on-insulator (Sili-c
The spot of the laser beam used in the SOI technique was circular as shown in the plan view of FIG. 4(b). In addition, Figure 4 (
bl shows the laser beam spot 42 scanning on the polysilicon surface 41, and ta+ in the figure shows the temperature distribution of the laser beam spot 42, where the horizontal axis shows the position of the laser beam spot and the vertical axis shows the temperature. Take.

The laser beam spot has the highest temperature at its center;
It is a Gaussian beam spot whose temperature decreases from the center outward. When the laser beam probe/nod scans the polysilicon surface 41 in the direction of the arrow in order to melt the polysilicon with such a beam spot, the melted polysilicon (liquid phase part) cools and solidifies into single crystal silicon. The solid-liquid interface 43, which is the boundary with the solid phase, has a shape opposite to the temperature gradient of the laser beam spot, and the melted polysilicon recrystallizes from both ends toward the inside, resulting in a grain boundary. ) 44 is formed as shown.

Thus, in recrystallization of polysilicon using a laser beam with a circular spot, single crystal grains of up to 5×5μ1
12, and there was a problem that a large area of single crystal silicon could not be formed.

In order to solve the above-mentioned problem, a crescent-shaped laser beam spot 31 shown in FIG. 3(b) was created.

The temperature distribution of such a crescent-shaped laser beam spot has peaks at both ends and is low at the center, as shown in FIG.

When such a beam spot is used to scan the polysilicon surface 41 in the direction of the arrow as shown in FIG. are formed only at both ends of the scanned portion of the laser beam spot, creating a larger single crystal area than in the case of a circular beam spot.

[Problem that the invention seeks to solve]

The laser beam annealing described above is performed by scanning the beam in the direction of the arrow in FIG. In either method, when the crescent beam moves in the direction shown in FIG. 3('b), single crystal silicon is formed in a large area.

By the way, when the crescent beam spot is scanned in the direction shown in Figure 3 (C), that is, when the direction shown in Figure 3 (bl) is taken as the forward direction, the solid-liquid interface that occurs after the beam spot scans in the return direction. As shown in Figure 3 (C1), grain boundaries 44 are generated inward from both ends of the area scanned by the crescent beam spot as shown in Figure 4 (BL). The result is the same as when a Gaussian beam is used.In this case, there is a problem that it becomes impossible to single-crystallize polysilicon over the entire area of the wafer.

The present invention was created in view of these points, and provides an apparatus that can perform single crystal annealing over a large area in the same way during laser annealing using a crescent beam spot, both during the scanning of the same beam spot and when the same beam spot is scanned. The purpose is to

[Means for solving problems]

Figure 1 (a) and ('b) and Figure 2 ta> and (1))
FIG. 1 is a diagram showing an embodiment of the present invention.

In the embodiment shown in FIG. 1(a), 11a and 11b are homogenizers with crescent beam spots, and they are arranged so that the crescent beam spots produced by each homogenizer are located opposite to each other. In this embodiment, the homogenizer 1 is
1b, the beam 13 is incident on the homogenizer 11b using a mirror 12b that changes the direction of the beam 13. When scanning in the return direction (-χ direction), the mirror 12b is retracted and the beam 13 is directed to the homogenizer 11b. The direction is changed by the mirror 12a for 11a so that it enters the homogenizer 11a.

In the embodiment shown in FIG.
When using homogenizer 1a, mirror 12c is
The mirror 12c is moved above the homogenizer 11b and the linear beam 13 is incident on the homogenizer 11b when the homogenizer 11b is used.

[Effect]

With the method described above, the crescent beam spot always creates the solid-liquid interface shown in Figure 3 (bl) regardless of whether the scanning direction is the forward or return direction, and single crystal annealing over a large area is realized. Ru.

〔Example〕

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

The homogenizer shown in Figure 1 is a rod-shaped body made of a light-transmissive material such as glass and tapered from one end (light entrance end) to the other end (light exit end), and the entire outer peripheral surface of the rod is It has a reflective coating and a crescent-shaped exit end. When a beam, for example a laser beam, is incident on such a homogenizer, the laser beam repeats total reflection within the homogenizer and is emitted from the exit end with a uniform energy density, but at this time, the shape of the beam spot is a crescent moon, just like the shape of the exit end. It takes shape.

In the first embodiment of the present invention, the scanning of the laser beam is χ
If the homogenizer 11b is used when the beam spot 14b moves in the χ direction (going direction), then the direction of the beam 13 is changed by the mirror 12b and the beam is incident on the homogenizer 11b. Scanning in the direction (when the beam spot 14a moves in the −χ force direction)
In this case, the homogenizer 11a is used, and for that purpose, the mirror 12b is moved away from the path of the beam 13,
The beam 13 is reflected by a mirror 12a and enters a homogenizer 11a.

With the method described above, the solid-liquid interface shown in Fig. 3(b) is always created in both the χ direction (outward direction) and -χ force direction (return direction) of the beam spot, and the polysilicon single crystal annealing is achieved. done efficiently.

In a modification of the first embodiment shown in FIG.
c, when the linear beam 13 is to be incident on the homogenizer 11a, the mirror 12c is placed above the homogenizer 11a, and when the linear beam 13 is to be incident on the homogenizer 11b, the mirror 12c is placed above the homogenizer 11a.
Move it above b. This modification also provides the same effects as the first embodiment.

A second embodiment of the invention is shown in FIG. 2, in which a pair of concave reflectors 21a replace the two homogenizers 11a, 11b of FIG. 1 to create a crescent-shaped beam spot. , 21b is used.

Referring to FIG. 2 (al), the linear beam 13 is
It has been confirmed through experiments that when irradiating light onto 1a, a crescent-shaped beam spot 22a is created because the reflecting plate 21 has a concave surface. When the linear beam 13 is irradiated onto the reflecting plate 21b, a crescent beam spot 22b is similarly created, but the crescent beam spots 22a and 22b have opposite shapes and face each other.

If the crescent beam spot 22b is used for scanning in the χ direction (in the χ direction) in FIG. In the −χ direction (return direction) scanning, the prism 23 located at the position shown by the solid line irradiates the linear beam 13 onto the reflecting plate 22a.

The effects of the second embodiment are exactly the same as those of the first embodiment, and the difference between these two embodiments lies in the use of a concave reflector instead of the homogenizer. Note that it is possible to use a prism in the first embodiment and a mirror in the second embodiment.

Although the above explanation has been made regarding an example in which a laser beam is used to single-crystallize polysilicon, the scope of application of the present invention is not limited to that case. In addition, although the explanation has been given as an example of scanning with a beam spot, the same applies to a case where the beam spot is stationary and the stage moves.

〔Effect of the invention〕

As described above, according to the present invention, in annealing using a crescent beam spot, exactly the same annealing is performed in the forward and return directions of beam spot scanning, which significantly improves the workability of annealing. It is effective.

[Brief explanation of drawings]

Figure 1 (al and (bl) are layout diagrams of the first embodiment of the present invention, Figure 2 (al and (b) are perspective views and front views of the second embodiment of the present invention, Figure 3 ta+ and (bl are A plan view showing the temperature distribution diagram of a crescent-shaped laser beam spot and the scanning of the same beam spot. Figures 4 and 4 (b) are plan views showing the temperature distribution diagram of the conventional circular laser beam spot and the scanning of the same beam spot. In Figures 1 to 3, 11a and 11b are homogenizers, 12a, 12b, and 12c are mirrors, 13 is a linear beam, 14a and 14b are crescent-shaped light beam spots, 21a and 2Ib are concave reflectors, 22a and 22b are crescent moon light beam spots, and 23 is a prism. Agent: Patent attorney Moto Kuki; Agent: Yoshiyoshi Osuga; Patent attorney: Yoshiyuki Osuga - 12 r questions - 4 Sui° 141)
D ok kuku i tofu month; Nshi 1 ρ Tsuku bow tL & 2 ΣA fig. 1, Δmi, 茅t9 ming] -- 2 palms meeting 24911 fig. 2 1 ↓ fig. 3 fig. 4 procedure ne ↑Correct text (method) % formula % 1. Display of the case Patent Application No. 58043 of 1985 2. Title of the invention Light beam annealing device 3. Person making the amendment Relationship with the case Patent applicant address Yozaki, Kanagawa Prefecture 1015 Kamiodanaka, Nakahara-ku, City (
522) Name: Fujitsu Co., Ltd. 4, Agent address: 1-31-3-808 Shinjuku, Shinjuku-ku, Tokyo (
(Delivery date: July 28, 1986) 6.1ii Correct subject matter In the brief explanation of drawing 41 on page 11 of Specification 7, Statement of Contents of Amendment 2111, the explanation regarding Figure 3 (the same page, lines 11-13)
shall be corrected as follows. Figure 3 ta+ and (bl are plan views showing the temperature distribution diagram of the crescent-shaped laser beam spot and the scanning of the same beam spot,
The tel in the same figure is a plan view showing the scanning of the crescent beam spot 7.

Claims (2)

[Claims] (1) Tapered from the light entrance end to the light exit end made of a light-transmitting material, the outer periphery is coated with total reflection, and the light exit end is a crescent-shaped pair of homogenizers (11a, 11b) that exit from the light exit end. shaped light beam spot (14a,
14b) are arranged so that they are opposite to each other, and in the χ direction scanning, the beam (13) is directed to one mirror (
12b) to be incident on one homogenizer (11b), and in -χ direction scanning, the beam (13) is incident on the other homogenizer (11a) using the other mirror (12a). A light beam annealing device. (2) The light beam according to claim 1, characterized in that concave reflectors (21a, 21b) are used in place of the homogenizers (11a, 11b).