JPS6147627A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To obtain a single crystal semiconductor layer having desired uniform plane orientation by providing an area which is narrower than the energy beam width to a part of the flat-shaped island. CONSTITUTION:After forming an insulation film, for example, SiO2 2 on a semiconductor substrate, for example, a silicon wafer 1, non single crystal semiconductor, for example, a polycrystalline silicon island 3 is formed in such a structure as being surrounded by an insulator such as SiO2 2. The flat shape of polycrystalline silicon island 3 has a narrow width portion B sandwiched by the wider regions A, C. The silicon island 3 thus obtained is irradiated with an energy beam, for example, argon CW laser with a power of 5-10W and scanning speed of 100mm./sec for recrystallization. The beam diameter is set larger than the width of narrow portion B of silicon island 3 at least for the direction of scanning the laser beam and the laser beam L is scanned to the portion C passing through the portion B from the portion A of silicon island 3. Thereby, the silicon of island 3 after irradiation of laser fuses and is recrystallized in accordance with scanning of laser beam L.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to semiconductor devices, particularly highly integrated, high-speed, high-performance, completely isolated semiconductor integrated circuits, that is, SOI (Se
m1conductor On In5ulator
) The present invention relates to a method for manufacturing a substrate for a device.

Conventional Structures and Their Problems SOI devices are being actively developed with the aim of realizing high-performance semiconductor devices with higher density and higher speed than ever before. S
As the most basic technology for creating OI devices,
There is a so-called single crystallization technique that forms a single crystal semiconductor layer on an insulating substrate. In the single crystallization technology, an energy beam such as a laser beam or an electron beam is irradiated onto an island of a non-single-crystal semiconductor surrounded by an insulator on an insulating substrate to melt the island-shaped non-single-crystal semiconductor. It is known that the recrystallization technique is relatively easy to obtain a single crystal semiconductor layer.

However, as described above, in the method of melting and recrystallizing an island structure semiconductor layer, it is difficult to control the plane orientation of single crystal islands.

Purpose of the Invention The present invention provides a method for melting and recrystallizing a non-single-crystal semiconductor layer by irradiating an energy beam, using an island structure that facilitates single-crystallization, and controlling the plane orientation of the formed single-crystalline island. This is a method for forming a single crystal semiconductor layer with a desired plane orientation.

Structure of the Invention The present invention provides a method for melting and recrystallizing an island-shaped non-single crystal semiconductor layer formed on an insulator on a semiconductor substrate by irradiating an energy beam such as a laser. By providing a narrow part in a part of the energy beam, when crystal growth progresses as the beam scans, some crystal grains formed on the beam incident side collide with each other, resulting in crystal grains. However, the growth of many crystal grains stops in the narrow part, and almost only one crystal grain grows, and when the subsequent island part melts and recrystallizes, the remaining part In this method, one crystal grain becomes a crystal seed, and the island behind the narrow part in the beam scanning direction becomes an almost perfect single crystal island. At this time, the crystal plane orientation of the single crystallized island is adjusted to the desired plane orientation by using the plane orientation anisotropy caused by the deposition conditions of the non-single crystal semiconductor layer deposited to form the non-single crystal semiconductor island. It is something to do.

DESCRIPTION OF EMBODIMENTS An embodiment of the present invention will be described based on the drawings. In Figure 1 (
a) is a plan view of an island structure silicon 3 in one embodiment of the present invention. A cross-sectional view along line xx' is shown in FIG. 1(b). After forming an insulating film such as 51022 on a semiconductor substrate such as a silicon wafer 1, a non-single crystal semiconductor such as a polycrystalline silicon island 3 is formed surrounded by an insulating material such as 51022. Above polycrystalline silicon island 3
The planar shape of has a narrow portion B narrowed by wide portions A and C.

An energy beam fc is applied to the silicon island 3 thus obtained.
Recrystallize by irradiating with a CW laser of argon at a power of 5 to 10 W and a scanning speed of 100 mm/sec. The state of recrystallization by laser irradiation is schematically shown in FIG. 1(C). Set the beam diameter to be at least larger than the width of the narrow part B of the silicon island 3 in the laser beam scanning direction, and scan the laser beam L from the part A of the silicon island 3 through B toward C. do. In this embodiment, the diameter of the beam L is larger than that of the portions A and C. After laser irradiation, the silicon with a height of 3 is melted and recrystallized as the laser beam L scans. At this time, the silicon island 3 is first irradiated with the laser beam L.
In the part A of , it is not necessarily a single crystal but has several crystal grains. However, in part B of the silicon island, multiple crystal grains generated in part A collide with the S i 0 interface around the narrowed island, and most of the grains stop growing. The growing crystal grains are weeded out, and by the time they reach part C of the silicon island, which has expanded again, they are almost a single crystal grain. Therefore, when silicon melts and recrystallizes at 0 part of the silicon island, the above B of the silicon island
Since the crystal grains that survive in the 0 part become seed crystals, the recrystallized silicon in the 0 part of the silicon island becomes an almost perfect single-crystal silicon island 3'.

The plane orientation of the 0 part of the single crystal silicon island 3' thus formed follows the plane orientation of the crystal grains that survived in the B part.

The sample having the cross-sectional structure shown in FIG. 2(a) is made of a polycrystalline silicon layer 4 formed by forming a layer 51022 on a silicon wafer 1 at a temperature of 610'C by, for example, the LPGVD (low pressure chemical vapor deposition) method. ing. Experiments have shown that the polycrystalline silicon at this time exhibits extremely strong growth anisotropy in the (11o) plane. Therefore, the above sample
As shown in the schematic plan view in figure (b), the laser beam L
The recrystallized silicon layer 4' formed by scanning while irradiating the laser beam is formed by crystal grain growth occurring from the edge of the laser beam scan, with the polycrystalline silicon in the non-irradiated area 4 acting as a seed. According to the experimental results, the recrystallized silicon layer 4
The crystal grains ' inherited the (11o) orientation anisotropy of polycrystalline silicon 4 and were mostly (11o) planes. Therefore, the crystal plane orientation of the recrystallized silicon island 3' shown in FIG.

The plane orientation anisotropy of polycrystalline silicon formed by the LPCVD method depends on the deposition temperature of polycrystalline silicon. However, with regard to the deposition temperature of polycrystalline silicon, if the deposition temperature is below 550"C, the deposition rate is extremely slow and is not practical.
The deposition rate is too fast and the reproducibility of thickness etc. is poor at temperatures above 750°C. This is desirable. An example is shown in FIG. For example, 6oo
Most of the plane orientations of polycrystalline silicon deposited near °C are (
1'10) surface, and at a temperature around 700'C,
It shows the growth anisotropy of the (100) plane. Therefore, if a polycrystalline silicon island with a desired plane orientation is formed in advance by the above method using growth anisotropy, the plane orientation of a single crystal silicon island formed by laser irradiation can be determined.

FIG. 4 shows a plan view of another embodiment in which the shape of the polycrystalline silicon island 3 is changed.

(al in FIG. 4) is such that the beam diameter of the A section is larger than that of the laser beam L, and the crystal grains grown in the A section grow using the unirradiated polycrystalline silicon at the laser beam irradiation end as seeds. However, the laser beam L at this time needs to be scanned to a position where the C part of the silicon island 3 can be completely melted. (This is an example where parts A and C are tapered. Also,
Figure 4 (C).

(d) shows an example in which the narrow portion of the silicon island 3 is closer to one side.

Effects of the Invention According to the present invention, when a single crystal semiconductor layer is formed on an insulator by energy beam irradiation, more perfect recrystallized islands can be formed, and the plane orientation of the single crystal semiconductor layer can be adjusted to a desired direction. This makes it possible to form elements such as transistors on the single-crystal semiconductor island to realize a high-performance SOI device.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of one embodiment of the present invention, and (a
) is a plan view of a silicon island, (b) is a cross-sectional view taken along the line XX/0, (c) is a conceptual diagram of a recrystallized silicon island formed by laser irradiation, and Figure 2 is a diagram of a silicon island formed by laser irradiation. ○2 Conceptual diagram of crystal grain formation when the silicon layer on the entire surface is recrystallized by laser irradiation. (a) in the same figure is a cross-sectional view of the sample, (b) in the same figure
) is a plan view, FIG. 3 is a graph showing the growth plane orientation anisotropy depending on the growth temperature of a polycrystalline silicon layer formed by the LPCVD method, and FIGS. FIG. 2 is a plan view showing the concept of the embodiment. 1...Silicon wafer, 2...5102
．． 3... Polycrystalline silicon island, 3'...
Recrystallized silicon island, L... Laser beam, A
...Beam entrance side part of silicon island, B...
...Narrow part of the silicon island, C...Beam exit side part of the silicon island. Patent applicant: Director of the Agency of Industrial Science and Technology Kawa 1) Hirobe Figure 1 Figure 2 Figure 3
(dl figure

Claims (3)

[Claims] (1) When forming a non-single crystal semiconductor island surrounded by an insulator on an insulating film on a semiconductor substrate, and melting and recrystallizing the semiconductor island by irradiating the semiconductor island with an energy beam, The planar shape of the semiconductor island has at least one narrow portion having a width narrower than the beam diameter of the energy beam, and the semiconductor island has a narrow portion having a width narrower than the beam diameter of the energy beam, and the semiconductor island passes from one end of the semiconductor island through the narrow portion to the other side. A method of manufacturing a semiconductor device, characterized in that the energy beam is irradiated while scanning an end portion. (2) Non-single-crystal semiconductor islands are formed by low-pressure chemical vapor deposition.
2. The method of manufacturing a semiconductor device according to claim 1, wherein the semiconductor device is formed from a polycrystalline silicon film deposited at a temperature range of 550°C to 750°C. (3) With respect to the scanning direction of the energy beam, the width of the semiconductor island in the part before the narrow part is wider than the width of the energy beam, and the part behind the narrow part is wider than the width of the energy beam. 2. The method of manufacturing a semiconductor device according to claim 1, wherein the island is a narrow planar island.