JPS59121825A - Fabrication of semiconductor thin film - Google Patents

Abstract

PURPOSE:To form polycrystal or single crystal of good quality on a substrate by beam annealing method by controlling scanning velocity of energy beam so as to be faster at the central part within the scanning range than at the end parts in both x-axis direction and y-axis direction. CONSTITUTION:A polycrystalline silicon film 204 or 5,000Angstrom , for example, is deposited on the surface of an SiN film 203 and this film 204 is annealed by irradiation and scanning with energy beam from the upper. At this time, the beam scanning of reciprocation in x-axis direction is performed within the scanning range of x-axis direction (0<=x<=xo) in the condition that v=vmax when x=xo/2 (e.g. 20m/sec) and v=vmin when x=0, xo which is slightly small value. In addition, the reciprocation of the beam scanning is made to be faster than velocity that temperature of the annealed parts decreases thereby keeping temperature of x-axis direction in the beam irradiation area uniform. Meanwhile, the scanning velocity of y-axis direction is made to be enough slow compared with that of x-axis direction and controlled so as to be faster at central part of the scanning range of y-axis direction thereby keeping a moving velocity of single crysta growth interface 301 in y-axis direction at a constant value.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a method for manufacturing a semiconductor thin film, and particularly to a method for crystallizing a polycrystalline or amorphous semiconductor thin film deposited on a substrate by irradiating it with a high-energy beam. Regarding improvements.

[Technical background of the invention and its problems]

There is a limit to miniaturizing the elements of conventional two-dimensional semiconductor devices to increase their integration and speed.As a means to overcome this limit, so-called three-dimensional semiconductor devices have been proposed in which elements are integrated in multiple layers. The most important issue in realizing a three-dimensional semiconductor device is how to form a high-quality semiconductor film on an insulating film. To solve this problem, a beam annealing method has been proposed in which a polycrystalline or amorphous semiconductor thin film on a substrate is scanned while irradiated with a high-energy beam to obtain a coarse-grained polycrystalline or single-crystalline semiconductor thin film.

As shown in Figure 1, the conventional beam annealing method basically involves scanning an energy beam at a constant speed in one direction (the In this method, the irradiation is performed while moving the irradiation step at a constant speed. However, with this beam annealing method,
iI] When using laser beams with a diameter of 20 m or more, it is difficult to form a single-crystal silicon thin film with a length of 100 μm and a width of 10 mm or more. Furthermore, the single crystal thin film that has been realized contains many defects such as dislocations and twins, and the locus of the scanned beam remains as unevenness on the crystal surface, making it difficult to obtain a single crystal of sufficiently high quality. Ta. This is because in the conventional beam annealing method, the beam scanning speed in the X-axis direction and the beam speed in the Y-axis direction are both constant, so the temperature at the periphery of the wafer, where heat dissipation is good, is lower than at the center. This is because temperature non-uniformity occurs within the beam irradiation area, and because the scanning speed in the X-axis direction is slow, there is a large temperature gradient in the X-axis direction near the beam irradiation point. This seems to be a big reason.

Further, as shown in FIG. 2, using a linear electron beam 101,
A method has also been proposed in which the semiconductor thin film is annealed by running it in the Y-axis direction shown by the arrow while keeping it seven parallel to the X direction. However, even with this method, the temperature in the X-axis direction at the beam irradiation point was made uniform! : It's difficult to scan,
Since the crystal growth interface often draws an arc like 102, the growth direction of the single crystal is not aligned in one direction. Kotame 05
It was difficult to grow more than one ×5 Pr grain.

Dormitory I Purpose of Invention] The present invention has been made in view of the above points.
jA = -7.7 Now 9-C is a sweet sweetfish.

The object is to provide a method of forming polycrystals or single crystals.

[Summary of the invention]

The present invention is an improved method of scanning and annealing while continuously irradiating a high-energy beam. Control the parts so that they are faster. This makes the temperature in the X-axis direction uniform in the beam irradiation area of the polycrystalline or non-quality semiconductor thin film on the substrate, makes the growth interface of the single crystal linear, and also keeps the moving speed of the growth interface constant in the Y-axis direction. It becomes possible to

〔Effect of the invention〕

According to the present invention, a semiconductor thin film of good quality can be obtained,
It becomes possible to provide practically sufficient characteristics as an element formation substrate of a three-dimensional semiconductor device.

[Embodiments of the invention]

Hereinafter, one embodiment of the present invention will be described in detail using the drawings. FIGS. 3(a) to 3(e) are cross-sectional views showing the manufacturing process of one embodiment.

A4L First, as shown in Figure 30, for example, P type (100
) direction on the surface of the single crystal silicon substrate 201,
An S IO 2 film 202 with a thickness of about 1 μm is formed as a film, and a SiN film 203 is formed thereon. This SiN film 122=, ! +H'jW o s is formed to facilitate single crystallization of the silicon film in the later beam annealing process.
,0+:'. Furthermore, it is assumed that the desired elements have already been formed on the silicon substrate 201 through a well-known process.Next, as shown in FIG. 3(b), the surface of the SIN film 203 is A polycrystalline silicon film 204 is deposited. Next, as shown in FIG. 3(C), the silicon film 204 is annealed by scanning an energy beam from above. 500mm silicon substrate to prevent diffusion.
The temperature was raised to 'c', a continuous electron beam was used as a beam source, the acceleration voltage of the electron beam was 10 kV, the beam current reaching the silicon substrate was 5 mA, and the beam spot diameter was 300 μmφ. In addition, as shown in FIG. 4(a), the beam scanning of the reciprocating motion in the X-axis direction is performed within the scanning range (O≦X≦XQ) in the X-axis direction, where x=XO//
2 and v = vmax (fc for example 20m/see
), x = O, Xo and V = Vmin, which is slightly small, and the annealed part is 1T''''
"゜-""゜゜" was-ii, X in the beam irradiation area
By keeping the temperature k uniform in the axial direction, the growth interface 30 of the single crystal f0 was made to form a straight line as shown in FIG. 4(b).

: sword) and the beam irradiation position in the y-axis direction.
1'・4 i14'jj Set the velocity distribution in the j-axis direction appropriately, and the X-axis direction i:ku'! 1 jj7, the temperature uniformity of the image was maintained. In addition, the scanning speed in the y-axis direction is made sufficiently slower than that in the The moving speed of the interface 30 in the Y-axis direction was kept constant. The locus of the beam scan was as shown in FIG. 4(c).

In this example, the above scanning speed is controlled using a temperature sensor with an infrared detector to detect the temperature of the beam irradiation point, and an electronic computer calculates the optimum speed of beam scanning and provides feedback to the electron beam irradiation device. I went to that method. In this way, the growth direction of single crystals can be perfectly aligned, and the growth interface speed of trenched single crystals can be kept constant, resulting in polycrystals and single crystals with larger grain sizes than before. It was done.

1 shown in Fig. 3(d) following the above Fig. 3(c) step.
A゜"1"1"゜"""゜゜゜゜゜ヲゲ/-e turn to form an element forming region separated by a ``''゛oxide film''゛゛, and this element region A dirt electrode 207 made of, for example, polycrystalline silicon is formed through the r-to oxide film 206-..., and the source and drain regions 1 and L Yr'o 8., ? o9 Formation Lte MOS } run) stat I1 t'=yl.Next, as shown in FIG.
3 and completed a three-dimensionally integrated semiconductor device.

In the above embodiment, a MOS} transistor was formed in a recrystallized silicon film, but a C-MOS} transistor,
Needless to say, it is possible to form all kinds of elements such as bipolar transistors and diodes, and by arranging these elements three-dimensionally using the present invention, three-dimensional devices with higher integration, higher performance, and more functionality than ever before can be formed. It became possible to realize integrated circuits. In the above embodiment, beam scanning is used for annealing in both directions as shown in FIG. 4(C), but the present invention can also be applied to a blanking scanning method as shown in FIG. Furthermore, the effects of the present invention can be expected in semiconductors other than silicon, and by combining these, it is possible to simultaneously provide display circuits, sensing circuits, etc. in addition to conventional self-memory circuits and logic circuits. Multifunctional element 2
You can make it up. Further, although the above embodiments used an electron beam, other energy beams such as a laser beam, infrared rays, and visible light such as sunlight may also be used. Further, the At electrode in the step (e) in FIG. 2 may be made of other metals. Further, although the scanning speed of the beam is a maximum of 20 m/sec in the above embodiment, it may be faster than this.

In addition, the present invention can be modified in various ways without departing from its spirit.

[Brief explanation of drawings]

1 and 2 are diagrams for explaining the conventional energy beam scanning method, FIGS. 3(a) to 3(e) are sectional views showing the manufacturing process of an embodiment of the present invention, and FIG. a) ~ (c
) is a diagram for explaining the energy beam scanning method of the same embodiment. 201... Single crystal silicon plate, 2o2...5lo2
film, 2θ3...SiN film, 2o4...polycrystalline silicon film, 204'...single crystal silicon film, 2o5...
Field oxide film, 206... Dirt oxide film, 207
... Dirt electrode, 208, 209... Source/drain region, 210... Insulating film, 211-213...
At electrode, 3θ1... single crystal growth interface. Applicant: Makoto Ishizaka, Director of the Agency of Industrial Science and Technology ~Figure 1, Figure 3, Figure s3

Claims (1)

[Claims] In a method in which a semiconductor thin film is deposited on a substrate and the semiconductor thin film is continuously irradiated with an energy beam while being scanned to enlarge the crystal grain size, the scanning speed of the energy beam is set to an end point at the center of the scanning range. 1. A method for manufacturing a semiconductor thin film, characterized by controlling the manufacturing speed to be faster than the current speed.