JPS59132121A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To reduce crystal defects in a single crystal silicon layer by moving the position of irradiation in succession in the eccentric direction of a high light intensity section in laser beams and in the direction crossing with a line tying two high light intensity sections. CONSTITUTION:The distribution of light intensity in laser-beams is adjusted so that two high light intensity sections 6a, 6b are formed at positions biassed from the center of laser-beams and an intermediate light intensity region 7 in a trailing skirt in different length la, lb on the beam center side of these high light intensity sections 6a, 6b is formed. A laser-beam irradiating region is moved in the eccentric directions of the two high light intensity sections 6a, 6b and in the direction of (m) crossing with a straight line tying the high light intensity sections 6a, 6b.

Description

Detailed Description of the Invention (a) Technical Field of the Invention The present invention relates to an SOI (SOI) in which a semiconductor element is formed on a single crystal silicon layer disposed on an insulating substrate (substrate or film).
The present invention relates to a method of manufacturing a semiconductor device having an iliconon insulator structure, and particularly to a method of monocrystallizing a silicon layer formed on an insulating substrate in the manufacturing process.

(b) Background of the technology Recently, semiconductor devices with SOI structure have become popular due to their advantages such as high isolation voltage, which makes it easy to integrate devices at high density, and small isolation stray capacitance, which enables faster device operation. Attention has been paid.

In the semiconductor device having the SOI structure, the single crystal silicon (St) layer on which the semiconductor element is fabricated is an amorphous or polycrystalline silicon layer deposited on an insulating base consisting of a substrate or a film.
It is formed by melting and recrystallizing the t-layer. In the single crystallization, a laser annealing technique is often used in which the heating position is sequentially moved by laser beam irradiation.

(Q Conventional technology and problems The laser that was conventionally used for the above laser annealing
The beam was either a Gaussian beam with a high light intensity area at the center of the beam or an elliptical beam with a relatively flat optical velocity distribution without a sharp high light intensity area.

When the conventional laser annealing technique was used to single-crystallize the amorphous Si layer deposited on the insulating substrate, when a Gaussian beam having a high light intensity region at the center was used, As schematically shown in Figure 1,
Crystals that flow from the periphery toward the center in the direction m in which the heating region moves and deeply bite into the center of the single-crystal Si layer mSi formed by one heating region movement in the direction of the arrow m There are problems in that crystal defects occur and the area in which semiconductor elements can be formed are restricted, resulting in a decrease in manufacturing yield, and that the crystal defects extend to the element formation area, resulting in a decrease in element performance.

Furthermore, when an elliptical beam is used, although it is possible to widen the beam width, there is a problem in that sufficient laser power cannot be obtained, making it difficult to obtain a high-quality single-crystal Si layer.

(d) Purpose of the Invention The present invention provides a laser annealing method capable of eliminating the above-mentioned problems and converting an amorphous or fractured silicon layer on an insulating substrate into a high-quality single crystal. The purpose is to improve the performance and manufacturing yield of semiconductor devices with an SOI structure.

(e) Structure of the Invention That is, the present invention involves monocrystallizing a silicon layer formed on an insulating substrate in the manufacturing process of a semiconductor device in which a semiconductor element is formed on a single crystal silicon layer provided on an insulating substrate. In this case, a laser beam is used that has two high-light intensity parts at positions offset from the center of the beam, and a medium-light-intensity region with tails of different lengths on the side of the beam center of these high-light intensity parts. The irradiation position by the laser beam is
The laser beam heating of the silicon layer is performed while sequentially moving the beam in the eccentric direction of the high light intensity portion and in the direction intersecting a line connecting the two high light intensity portions.

(f) Embodiment of the Invention The present invention will be described in detail below with reference to an embodiment of the invention.

Figures 2 (a) to (c) are process cross-sectional views in one embodiment of the present invention, and Figure 3 is a plane light intensity distribution diagram (a) and cross-sectional light intensity distribution of the laser beam used in the same embodiment. Figure (b),
FIG. 4 is a schematic structural diagram of an example of a laser generator used in the same embodiment, and FIG. 5 is a schematic top view of a single crystal silicon layer formed according to the same embodiment.

For example, silicon dioxide (SiO□) can be produced by the method of the present invention.
When forming a semiconductor device having an SOI structure using a film as an insulator substrate, for example, 1 to 1 are deposited on a silicon (Si) substrate 1 by a thermal oxidation method or the like as shown in FIG. 2(a).
A 5in2 film 2 with a thickness of about 1.5 [μm] is formed, and then an amorphous film with a thickness of about 0.4 to 0.5 [μm], for example, is formed on the 5in2 film 2 by a method such as vapor deposition. Quality St layer 3'
form.

Next, as shown in FIG. 2(b), the amorphous Si and
.

For example, a silicon nitride (SisN+) film with a thickness of about 500 [A:] and a film with a thickness of 0.5 to 0.6 [jlm:] is formed on the layer 3'.
] After forming an antireflection film (also serving as a weight) 4 made of laminated cinsilicate glass (PSG) films, the antireflection film is heated to about 450° C.E. in air, for example. 4, the entire surface of the amorphous Si layer 3' is sequentially heated with a laser beam L while moving the substrate (arrow m indicates the direction of movement of the heating area), and the amorphous St layer 3' is sequentially melted and recrystallized. Three single crystal St layers are formed (5 is a molten Si layer).

In the method of the present invention, the laser beam used for the laser annealing process is usually continuous wave argon (CWAr) having a wavelength of about 0.45 to 0.53 [μm], which has a large absorption coefficient in Sl. Uses a laser beam. The distribution of light intensity in the laser beam has two high light intensity parts 6a and 6b at positions offset from the center of the laser beam L, as shown in FIG. 3(a). Adjustments are made so that a medium light intensity region 7 with skirts of different lengths Aa and tb is formed on the beam center side of the high light intensity portions 6a and 6b.

In the figure, 8 indicates a low light intensity region. The diameter d of the beam is, for example, about 60 [μm], and the laser output is about 4 to 8 [W]. Figure 3 (b) shows the laser
It is a diagram schematically showing the cross-sectional light intensity distribution of the beam in the direction of the arrow A-A'.

The CWAr laser beam having the above-mentioned light intensity distribution is transmitted to external resonant mirrors C, , C2 in a gas laser generator R (Ar laser tube Ar-LT) as shown in FIG. 4, for example.
It is formed by two-dimensionally changing the opposing angles of the two.

In the figure, E, , E are electrodes, G is a discharge, L is a laser beam, and B is a Brewster window.

Further, in the method of the present invention, the laser beam irradiation area is moved in the eccentric direction of the two high light intensity parts 6a, 6b in FIG. For example, 50 Crra in the direction of the arrow m that intersects at right angles.
n/yc].

Next, the antireflection film 4 is removed by a conventional etching technique, and the single crystal Si layer is patterned by a conventional photolithography technique.
Single-crystal St layer patterns 3a, 3b, etc. separated into islands are formed on the film 2.

Although not shown hereafter, single conductor elements are implanted into these single crystal St layer patterns, and the shape of the insulating film shown in FIG. This diagram schematically shows the top surface of the Si layer 3.
As shown in the figure, a single crystal Si layer 3 formed by the above method
The crystal defects growing from the periphery, that is, the interface with the polycrystalline Si layer 3' to the center of the single-crystal Si layer 3, are trenches in the region Mh melted with high light intensity, and the length thereof is longer than that of the conventional one. Since it is extremely short (about several micrometers) compared to , a high-quality single crystal layer 3 having a wide area can be formed.

In the above embodiment, the present invention is applied to a single crystal S on a SiO2 film.
Although the method of the present invention was applied when forming an i-layer, the method of the present invention is not limited to the above-mentioned embodiments, and can be applied not only to insulating films other than SiO2 films but also to forming single-crystal Si layers on insulating substrates. -Use-te-kiru. It may also be an insulating substrate on which an insulating film of stationery is deposited.

Furthermore, the diameter of the laser beam and the laser power.

The thickness of the Si layer and the like are not limited to those in the above embodiments.

Furthermore, the moving direction of the laser irradiation position may be any direction that intersects the line connecting the high light intensity parts of the laser beam, and is not limited to the direction that intersects at right angles as shown in the above embodiment.

(g) Detailed Description of the Invention As described above, according to the present invention, crystal defects in a single crystal silicon layer formed on an insulating substrate are significantly reduced. Therefore, it is possible to improve the quality and manufacturing yield of semiconductor devices having an SOI structure.

[Brief explanation of the drawing]

Figure 1 is a schematic top view of a single crystal silicon layer formed by a conventional laser annealing method using a Gaussian beam, and Figures 2 (a) to (c) are steps in one embodiment of the method of the present invention. 3 is a planar light intensity distribution diagram (A) and a cross-sectional light intensity distribution diagram (B) of the laser beam used in the same example, and FIG. 4 is an example of the laser generator used in the same example. FIG. 5 is a schematic top view of a single crystal silicon layer formed according to the same example. In the figure, 2 is a silicon dioxide film, 3' is an amorphous silicon layer, 3 is a single crystal silicon layer, 3a and 3b are single crystal silicon layer patterns, 4 is an antireflection film, 5 is a molten silicon layer, and 6 a p 6 b is the high light intensity region of the laser beam, 7 is the site intensity region, 8 is the low light intensity region, L is the laser beam, Ar -LT is the Ar laser tube, CX, C,
are external resonant mirrors, I, ,E. is an electrode, G is a discharge, D is a crystal defect, Mh is a region melted with high light intensity, m is an arrow in the direction of movement of the laser irradiation region, and t
a, tb are the lengths of the original intensity region, and d is the diameter of the laser beam. Early 1 flash? Picture number 3 Prisoner v-4 Picture number 5 Drunkenness

Claims (1)

[Claims] In the manufacturing process of semiconductor devices in which semiconductor elements are formed on a single-crystal silicon layer provided on an insulating base, when the silicon layer formed on the insulating base is single-crystallized, the beam is placed at a position offset from the center. Using a laser beam that has two high light intensity parts and a medium light intensity range with different lengths on the beam center side of these high light intensity parts, the irradiation position by the laser beam is adjusted to A semiconductor device characterized in that the silicon layer is heated with a laser beam while the laser beam is sequentially moved in an eccentric direction of a high light intensity portion of the laser beam and in a direction intersecting a line connecting two high light intensity portions. manufacturing method.