JPS5963721A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To single-crystallize a poly Si by a method wherein two laser lights of different wavelengths are temporarily formed into the same ray flux and made to pass through a prism, and a wafer at a fixed position is irradiated, and the interval between the two light points is arbitrarily controlled. CONSTITUTION:The Ar laser light A and the YAG laser light B are gathered into one beam flux by means of a half mirror 5, further reflected on a mirror 6, and then reciprocated by a scanning system 7 nearly in the direction of y at a constant period and amplitude. Since the laser light A and B have different wavelengths, A branches to right, and B to left, resulting in the generation of the two light points 1 on the wafer 3. The scanning system 7 is a regular hexangular prism, rotates around a shaft 7-3, has reflection mirrors 7-4 on side surfaces, and the bottom surface of the prism 8 is parallel with the x-y plane. The variation of the distance between the wafer and the prism enables to easily control the interval of the light points; when the interval is several ten mum, the single crystallizaton of the poly Si is effectively performed.

Description

DETAILED DESCRIPTION OF THE INVENTION (1) Technical Field of the Invention The present invention relates to a method for manufacturing semiconductor devices using laser beams, and in particular to a method for manufacturing semiconductor devices using laser beams, and in particular, a method for manufacturing a semiconductor device by applying a plurality of laser beams having different wavelengths onto a wafer while maintaining a predetermined interval. The present invention relates to a method of manufacturing a semiconductor device using irradiation.

(2) Background of the technology In recent years, when manufacturing semiconductor devices, laser beams have been used, for example, to give a crystalline structure to an amorphous layer after ion implantation through laser annealing, or to give a single crystal structure to silicon using laser beams. It has already been widely used to form a substrate and use it as a substrate.

(3) Prior Art and Problems Conventionally, a method of using multiple laser beams to form a semiconductor substrate, that is, to single-crystallize polysilicon, is as shown in FIGS. A method is known in which laser beams Δ and B from two fixed laser oscillators are formed on a wafer 3 on a stage 2, and the stage 2 is Laser beam A.

A method of scanning by mechanically moving the spot in a direction perpendicular to the spot B (FIG. 1(a));
A spot 1 is formed by laser beams A and B from two laser oscillators on a wafer 3 on a fixed stage 2,
A method (FIG. 1(b)) has already been proposed in which the two laser beams are scanned by vibrating the laser beam 13 in a direction orthogonal to the B' spot. However, the first method requires precise mechanical movement of the stage, resulting in a very high cost.

It also has the disadvantage of being relatively prone to failure.

The second method can be realized by using, for example, a mirror and moving such a mirror, so that it is possible to form a low-cost and high-speed scanning device.

However, scanning at a predetermined interval using two laser beams, for example, has the drawback that adjustment is extremely difficult when two mirrors are used, which is a bottleneck in practical application. It became.

(4) Purpose of the Invention In view of the above-mentioned drawbacks of the conventional art, the purpose of the present invention is to form two closely spaced I.sup. An object of the present invention is to provide an effective method for manufacturing single crystal silicon.

(5) Structure of the Invention The feature of the present invention is that when polycrystalline silicon is made into a single crystal, two
Laser beams of different wavelengths are temporarily turned into a single laser beam passing through the same optical axis, and the single laser beam is made to enter a prism.

To provide a method for manufacturing a semiconductor device, in which a wafer on a stage provided at a predetermined position is irradiated with two separated laser beams emitted from the prism, and an interval between two spots formed by the two laser beams is arbitrarily controlled. This is achieved by

(6) Embodiment of the Invention An embodiment using the present invention will be described below with reference to the drawings.

FIG. 2 (al and fb) is a front view and a partial perspective view showing the configuration of an embodiment using the present invention. Figure 2 (a
), for example, 5145 blue-green laser beams A are generated from the Ar laser oscillator 4-1.

1,06μTT generated from YAG laser oscillator 4-2
A half mirror 5 is provided so that the infrared rays 13 of I and the Rayleigh' beams of two types of wave extensions are combined into one beam bundle on the same optical axis. A reflecting mirror 6 is provided behind the half mirror 5, and further scans the radar beam back and forth in the direction (y direction) perpendicular to the direction connecting the two spots 1 formed on the wafer 3. A scanning system 7 is provided for this purpose. The two laser beams that have passed through the scanning system 7 and have been combined into one are 1
A prism 8 made of crown glass, for example, is provided to separate the original, separate laser beams.

Her laser oscillator 4-1 and YAG laser oscillator 4-2
5145 blue-green laser beams Δ and 1 generated from
．． Both laser oscillators are arranged so that infrared rays B1 of 0.6 .mu.m are incident on the receiver half mirror 5 from directions respectively forming an angle of 45 DEG with respect to the half mirror 5, for example. Thereafter, the light beams are gathered together as a single beam on the same axis and reflected by a reflecting mirror 6, and then reciprocated in the y direction with a constant period and amplitude by a scanning system 7. The laser beams A and B, which are combined into a single beam bundle and make reciprocating vibrations, enter the prism 8, but since they are different types of beams with different wavelengths, the refractive index of the prism 8 made of crown glass is also A. , B are different. Therefore, when passing outside the prism 8, the prism 8 follows different paths respectively.
Go outside. However, since the refractive index of a culm with a high frequency is large, the blue-green radar beam of 5145 people generated from the Ar laser oscillator 4-1 is directed to the right, and the culm generated from the YAG laser oscillator 4-2 is directed to the right. The infrared ray B of 0.6 μm is split to the left to form two spots 1 on the wafer 3.

FIG. 2(b) shows the configuration of the scanning system 7 and its vicinity as shown in FIG. 2fa). -1 is provided with a rotating shaft 7-3 at the center of three bottom surfaces 7-2, and a reflecting mirror 7-4 is provided on each of the six side surfaces. The prism 8 made of crown glass is placed at a predetermined position with its bottom portion parallel to the xy plane in the figure.

For example, a rotating body 7 rotating at a constant angular velocity in the x-y plane
-1, two types of laser beams A and B, which are bundled into a single beam bundle and proceed in the same x-y plane, are reflected by an arbitrary reflection mirror 7-4 on the side surface of the rotating body 7-1. It is reflected at the point and enters Brizno 8. The two types of laser beams A and B, which entered the prisms J and B as a single beam bundle, follow different paths within the prism 8.

Zunawaji Separates into two laser beams A and B and passes through prism 8
Go inside. In other words, the laser beams Δ and B, which were gathered into one beam through the prism 8, are split into two parallel beams in two directions through the prism 8, and the laser beam A, which has a short wavelength, goes in two directions. Laser beams B with longer wavelengths are separated into +2 directions. At the same time, the laser beam is scanned in a direction parallel to the X-axis by a scanning system 7 composed of a rotating polygonal column 7-1. That is, the rotating body 7- which constitutes the scanning system 7
1 at a predetermined angular velocity, the reflecting mirror 7-7I attached to the side surface of the rotating body 7-1 also rotates at a constant angular velocity.

On the other hand, the laser beam always travels straight in a fixed direction and on a fixed path position until it enters the first reflecting mirror 7-4, but since the above-mentioned reflecting mirror 7-4 performs a fixed rotational movement, When the locus of the incident point position of the laser beam on 7-4 is traced, it becomes G on the xy plane. In other words, it is parallel to the x-y plane and within a certain range, so the optical path after reflection at the reflecting mirror 7-4 is also rotated so that all six reflection mirrors 6Jt 7-4 are perpendicular to the x-y plane. Because it is on the x-y plane,
It advances while reciprocating vibration within a predetermined width. After that, it passes through prism 8 and is separated into two laser beams A and 'B, or x
- It is similarly divided into two pieces on the y plane and moves with the same reciprocating vibration at the same period.

FIG. 3 is a diagram showing a transmission optical path within the prism 8. FIG.

In the figure, the angle of deviation in direction between the incident ray ■ and the exit ray R is δ, the apex angle of the prism is α, and the apex.

Let the above four points of the entrance point, the intersection of the normal at the entrance point and the normal at the exit point, and the exit point be a, b, and cd, respectively. Further, the intersection of the extension line of the incident light ray and the extension line of the exit light ray is assumed to be e. Further, the angles formed by the normal line of the incident ray and the exit ray are defined as i and il, respectively.

la+lC=π ・ ・ ・ ・ ・ ・ ・ ・
・ ・(1) In quadrilateral bcde, le='1rc-(jb+Zc-1-Zd)=2π--
(i-tlC,4-i')...(2)+11. +2
From equation 1, 1π-(2π-(i+π-αl i') 1=i-
) i'-α (:3) Therefore, the deviation angle δ is determined from the relational expression (3) between the incident angle, the exit angle, and the apex angle.

FIG. 4 is an explanatory diagram showing the positional relationship between the prism J1, which is a component of the present invention, and the wafer.

In the figure, the distances between the incident point and the wafer 3 and the exit point and the wafer 3 are subtracted by l, and the distance between the spots of the two types of laser beams 1fiA and B is D. Further, the apex angles between the incident light beam and the exit light beam at the prism J due to B are δ and δ, respectively, and the Q) difference between them is defined as Δδ−δ−δ.

When Δδ<<1, it can be regarded as D~ΔδL, or when α is sufficiently small, it can be regarded as D~Δδl.

For example, the angle i between the incident wave and the normal at the point of incidence is 3(1
', the apex angle α is 10', and the 5 of the laser oscillator 4-i is
145 people and 1.06μI of YAG laser oscillator 4-2
The refractive index of B is 1.519°1.
512, δ = 25.22°, δ = 25.15°, and therefore Δδ−〇, 07°.Then, the distance l from the prism 8 to the wafer 3 is, for example, 8.21111
In this case, the distance between the two laser beams A and 13 (I) + is D + ~0.07X (π/180) X 8.
2 (+u+) to 9 (μm).

For example, if the distance l from the prism 8 to the Ueno X3 is 24.6 mm, the spacing D2 between the spout and the nose
．． 07X (π/180) X 24.6 (dragon) ~ 27 (μm).

Figure 5 (al to (C1) is a plan view showing the scanning of a spot on a wafer by two types of laser beams Δ and B using the present invention, a diagram of the intensity distribution of light on the wafer, and Each figure shows a formation distribution map of crystalline silicon.

In Fig. 5 ta+, two types of laser beams A and 'B are irradiated onto the wafer 3 from directly above, and at the same time, the distance 1] between the spots 1 caused by both beams is kept constant at -. The area of spot 1 is moving. By irradiating the laser beam, a single crystal C is formed at the center of the spot, and poly-like grains M are formed at the outer periphery.

The two types of laser beams A and B, which have been traveling as the same beam bundle of one tree, return to the original laser beams that were separated into two trees at the prism 8, and are separated from the prism 8 by a predetermined distance. Spots 1, which are two irradiation areas, are formed on the stage 2 and the bar 3 provided. The distance MltD between the centers of the two spots is, for example, about several tens of μm,
In addition, it was found that the larger the size of both sposo There is also the fact that it does not rise,
On the other hand, as mentioned above, the distance between the spots ^+tD is.

For example, the distance a between the prism and the wafer, the apex angle α of the prism
, the incident angle i can be controlled to a constant value by adjusting the incident angle i, etc., making it possible to form an effective single crystal.

In FIG. 5 tb+, the light intensity shows a distribution different from the Gaussian type, that is, it shows a distribution map in which the peak is divided into two. Then, on the wafer after laser irradiation, the central region C on the scanning line is a single crystallized region that will become the semiconductor substrate, and the two intermediate regions M next to it are the peripheries of two polylike regions containing crystal grains. Region F constitutes a polycrystalline portion.

For example, the peripheral region F, which is not exposed to the laser beam spot after scanning by laser beam irradiation, is made of polycrystalline silicon, so there are many crystals with at random directions, and one of them has two peaks that are in contact with each other. In the intermediate region M, which is the peripheral part of the laser beam, crystal grains (grains) larger than the crystal grains constituting polycrystalline silicon are formed due to the low temperature of the irradiated part after scanning by the laser beam irradiation. A polylike portion is formed. On the other hand, the central region C that is scanned by the laser beam irradiation is irradiated at a predetermined distance group 11, for example, at a distance of several tens of pm: Since the temperature of the central area 14C was slightly lower than that of both spots 1, the temperature of the central area 14C was returned to room temperature earlier than the two peak areas, but later than the aforementioned middle area M. In the low-temperature soil, the middle region M has already returned to normal temperature and a polylike part is formed. Therefore, during the temperature drop in the central rl+, !TI region C, the polylike part in the middle region M is formed. As a result, the polycrystalline silicon in the peripheral region F is transferred from the central region C to l.
'M4 i''ilf, the intermediate region M is not affected by polycrystalline silicon and good Elχ crystal silicon is formed between the two peak parts.

(7) Effects of the Invention As mentioned above, when the present invention is used, two laser beams of different wavelengths are mixed and made to enter the beam J1 as the same bundle of rays, thereby making it possible to combine two adjacent spots. For example, by changing the distance between the wafer and the prism, the spacing between the two spots can be easily controlled. This has the effect of allowing easy formation.

[Brief explanation of drawings]

Figure 1 (al and (b) shows the power of crystallization during -τ, 1; Fig. 2 ta+ and (
bl is a front view and a partial perspective view of an embodiment of the present invention;
No. 31-1 is a diagram showing the permeation path in the prism J, FIG. 1 shows a plan view showing the scanning of a spot on a wafer using the present invention, a diagram of the intensity distribution of light on the wafer, and a diagram of the formation distribution of single crystal silicon, :1, by scanning the laser beam. 1... Spot, 2... Stage, 3...
Sea urchin r-ha, 5...Half mirror-27...Sugotyansiswomu, 7-4...Reflector, )
(...prism, Δ...5145 rays of light, B...1.06/lnt beam, 0...central area, ■)... Interval between both spots, F... peripheral area, I... incident ray, M... intermediate area, R... exit ray,
α...Apex angle of prism J., δ...Angle deviation of incident and exit rays, p...Distance between prism J. and stage. 21st -” (α) 2nd night (bl 3I!l 3rd LN3EI Ns mouth

Claims (2)

[Claims] (1) When monocrystalizing polycrystalline silicon, two types of laser beams with different wavelengths are temporarily made into a single laser beam passing through the same optical axis, and the single laser beam is input into a prism. S-U: The prism is emitted and two separated laser beams are irradiated onto a wafer on a stage provided at a predetermined position.-U: The interval between the two spots by the two laser beams is arbitrarily controlled. A method for manufacturing a featured semiconductor device. (2) A patent claim characterized in that each time the single laser beam is reflected by a reflecting mirror attached to a polygonal rotating body, the laser beam is vibrated and scanned. A method for manufacturing a semiconductor device according to item 1.