JPH01147824A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To form a single crystal reflecting the surface orientation of polycrystalline Si onto an insulating film by selectively implanting ions in high concentration to the insular thin-film polycrystalline Si having surface orientation anisotropy shaped onto the insulating film and melting and recrystallizing the polycrystalline Si by laser beams. CONSTITUTION:Poly Si 3 having surface orientation anisotropy is formed insularly onto an insulating film 2 composed of SiO2 etc., shaped onto a substrate 1 consisting of Si, etc., through a CVD method, etc. One parts of poly Si 3 are covered with resists 4, ions 5 in high concentration such as Si, Ar, etc., are implanted from an upper section, and the surface of an ion implanting section in the poly Si 3 is brought to an amorphous state, The resists 4 are removed, and laser beams are scanned in the direction of the arrow 6. Since the optical absorption of amorphous Si is better than poly Si, a polycrystalline section 3A is brought to a semifused state, and a section 7, the surface of which has an amorphous section, can be brought to a completely melted state. Consequently, since an unmelted crystalline nucleus in the semifused section 3A is used as a nucleus and recrystallization is generated, single crystal Si reflecting the surface orientation of polycrystalline Si3 can be shaped onto the insulator 2. A design is made freer than conventional examples and a process simpler than them.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a method of manufacturing a semiconductor device, particularly a highly integrated, high-speed, high-performance, fully insulated semiconductor integrated circuit, that is, an S
OI (Semiconductor On In5u
(lator) The present invention relates to a method of manufacturing a substrate for a device.

BACKGROUND OF THE INVENTION In recent years, stacked devices have been actively developed with the aim of increasing the density and speed of semiconductor integrated circuits.

Liquid removal for forming stacked devices is also important in the technology of forming a single crystal semiconductor layer on an insulator.

Among these, there is a technology that melts the island-shaped non-single crystal semiconductor by irradiating an energy beam such as a laser beam or an electron beam onto an island-shaped non-single-crystal semiconductor formed in isolation on an insulator to make it into a single crystal. This is a technique that allows a single crystal layer to be obtained relatively easily. However, simply melting the non-single-crystal layer and turning it into a single crystal does not align the plane orientations of the single-crystal semiconductor, resulting in variations in device characteristics. Therefore, efforts are being made to control the plane orientation of single crystal semiconductors.

Conventionally, laser recrystallization of non-single-crystal silicon on an insulator uses seeds from a silicon substrate with openings in the insulator to form single-crystal silicon with controlled plane orientation. There was a method without seeds. Methods for forming single-crystal silicon with a controlled plane orientation using a seedless laser recrystallization method include the two-step laser annealing method [Reference Proceedings of the Japan Society of Applied Physics, Autumn 1988, Proceedings 412], and partially groove-shaped There is a polycrystalline seed method using a heat mink [Reference Proceedings of the Japan Society of Applied Physics, Autumn 1986, 486].

The two-step laser annealing method will be explained with reference to FIG. 3. First, an island-shaped polycrystalline silicon 31 having a plane orientation anisotropy is formed on an insulating film 30. In the first step laser annealing, in the structure shown in FIG. 3, a laser beam is scanned perpendicularly to the longitudinal direction of the island-like polycrystalline silicon 31 as shown by an arrow 31 to melt the island-like polycrystalline silicon 31 and return it to the original state. Artificial seed crystal part 33 reflecting the plane orientation of polycrystalline silicon
form. Next, as a second step laser annealing, a laser beam is scanned parallel to the longitudinal direction of the island-shaped polycrystalline silicon 31 as shown by an arrow 34, and the polycrystalline silicon 31 is
recrystallize. At this time, the artificial seed crystal part 33 has larger crystal grains than other polycrystalline silicon parts and has a higher reflectance of laser light, so if an appropriate laser power is selected, the artificial seed crystal part 33 will be semi-molten, and the other parts will be half-molten. It can be brought to a completely molten state. At this time, crystal growth occurs from the unfused core of the semi-molten artificial seed crystal portion 33, and single crystal silicon reflecting the original 310-plane orientation of the island-shaped polycrystalline silicon is obtained.

Next, polycrystalline seed laser recrystallization provided with a heat sink will be described. (See Figure 4).

First, an insulating film 41 having a thermal conductivity lower than that of silicon is provided on a silicon substrate 4o, and an island-shaped polycrystalline silicon 42 having surface orientation anisotropy is formed thereon. Also, at this time, a groove 43 that does not reach the silicon substrate is provided in a part of the insulating film under the island-like polycrystalline silicon 42 to serve as a heat sink. When a laser beam is scanned and recrystallized along the longitudinal direction of this island-like polycrystalline silicon 42, the insulator has a lower thermal conductivity than the polycrystalline silicon 42, and the base insulating film 41 is lower in the groove 43 than in other parts. Because it is thin, heat easily escapes to the silicon substrate 4o.
Groove 43 can be formed by selecting appropriate laser power and groove depth.
It is possible to make the polycrystalline silicon in some parts semi-molten and in other parts completely melted. At this time, the island-like polycrystalline silicon 42 grows crystals using the unmelted silicon grains in the groove 43 portion as nuclei, and single crystal silicon reflecting the plane orientation of the original polycrystalline silicon 42 is obtained.

Problems to be Solved by the Invention In the method of using seeds from a silicon substrate, it is necessary to shift the seed position each time the layers are stacked when creating a multilayer device, which reduces the degree of freedom in design and the effective area for creating a denomination (chair). On the other hand, if we look at the seedless method, the two-step laser annealing method (see Figure 3) requires two laser annealing steps, and the first step laser annealing process shown by arrow 32 requires two laser annealing steps. In annealing, all polycrystalline silicon exposed to laser light turns into artificial seed crystals whether we like it or not, which poses a problem in terms of the degree of freedom in the position of artificial seed crystals, and also creates constraints in terms of design.

Regarding laser recrystallization of the island-shaped polycrystalline silicon 42 having a groove 43-shaped heat sink as shown in FIG.
Since there is a step in the polycrystalline silicon 42 at the groove 43, good recrystallization is difficult because grain boundaries are generated at the step during recrystallization. Furthermore, in order to eliminate this level difference, the number of steps will increase if a buried type is used.

The present invention has been made in view of the drawbacks of the conventional method of controlling the plane orientation of recrystallized silicon by seedless laser recrystallization of polycrystalline silicon on an insulating film. The present invention provides a method for recrystallizing crystalline silicon using laser light without seeds and overcoming the above-mentioned problems.

Means for Solving the Problems The method for manufacturing a semiconductor device of the present invention involves forming an island-shaped thin film polycrystalline silicon having plane orientation anisotropy on an insulating film, and selectively applying high concentration ions to the polycrystalline silicon. After the surface of the ion-implanted portion of the polycrystalline silicon is made amorphous by implantation, the polycrystalline silicon is recrystallized under appropriate conditions for the ion-implanted portion using a laser beam. The ion-implanted part of the polycrystalline silicon is completely melted, the ion-unimplanted part of the polycrystalline silicon is left in a semi-molten state, and crystals are grown using the unmelted polycrystalline silicon grains in the ion-unimplanted part as nuclei. , a method of forming a single crystal reflecting the plane orientation of the polycrystalline silicon on the insulating film.

Effect When selectively high concentration ions are implanted into island-shaped polycrystalline silicon as in the present invention, the surface of the implanted portion becomes amorphous. The amorphous portion has a higher light absorption coefficient than the non-injected portion. In this state, by scanning the laser beam in the longitudinal direction of the island-shaped polycrystalline silicon, the injected part is completely melted and the non-injected part is semi-molten, and crystals are formed with the unmolten silicon grains in the non-injected part as nuclei. Growth is realized, the plane orientation of polycrystalline silicon is reflected, and the plane orientation of recrystallized silicon is controlled. Therefore, it is possible to arbitrarily and easily form a seed crystal in a desired shape at a desired location without creating a step, and recrystallization of polycrystalline silicon can be performed with one laser irradiation.

Example A more detailed explanation will be given below based on the drawings.

FIG. 1 shows an island-like poly(polycrystalline) silicon 3 formed on an insulator 2. As shown in FIG. The insulator 2 is made of, for example, SiO□ produced by a CvD (chemical vapor deposition) method. For example, a silicon or quartz substrate is used for the substrate 1, and a semiconductor element is formed on the silicon substrate.

The island-shaped polysilicon 3 is formed from a polycrystalline silicon film with strong plane orientation anisotropy formed by CVD (chemical vapor deposition) method, etc., and has the same plane orientation anisotropy as the polycrystalline silicon film. It has directionality.

The following table shows the plane orientation of polycrystalline silicon films formed by the LPGVD (low pressure chemical vapor deposition) method and the MPCVO (normal pressure chemical vapor deposition) method.

As shown in this table, polycrystalline silicon films formed by CVD (chemical vapor deposition) have strong plane orientation anisotropy depending on the formation temperature. In the present invention, the island-shaped polycrystalline silicon 3 may be formed using a strong (10
0) Form a polycrystalline silicon film with planar orientation.

Next, in order to selectively implant ions into the island-shaped polycrystalline silicon 3 shown in FIG. . Next, by implanting high-concentration ions 6 from above, the surface of the resist-free portion of the island-like polycrystalline silicon 3 is made amorphous. For example, the ions to be implanted are 8i
and mur etc. are used.

Then, as shown in FIG. 1G, the laser beam is scanned in the longitudinal direction 6 of the island-shaped polycrystalline silicon 3. In Figure 1C, 3
7 is a polycrystalline portion into which ions are not implanted, and 7 is an ion implanted portion whose surface is amorphous. Amorphous silicon 7
has a larger light absorption coefficient than polysilicon.
The figure is a graph showing the light absorption coefficients of single crystal silicon and amorphous silicon with respect to the wavelength of light. Looking at Figure 2,
For example, for YAG laser oscillation light with a wavelength of 1 μm, crystalline Si has an absorption coefficient of 102 (tttt-'), and ion-implanted amorphous silicon has an absorption coefficient of approximately 5X10'(cm-').
There is a difference of about 60 times. The absorption coefficient of polycrystalline Si is somewhat larger than that of crystalline silicon, but considerably smaller than that of amorphous silicon.

Therefore, by optimizing the power and wavelength of the irradiated light when scanning the laser beam, the part 7 where high concentration ions are implanted and whose surface is amorphous silicon can be completely melted, and the polycrystalline silicon part 3 can be melted by half. A state called melting can be achieved. At this time, crystal growth occurs with the unmolten silicon grains of the three semi-molten parts as nuclei, and the recrystallized island-like single crystal silicon reflects the crystal axis of the original island-like polycrystalline silicon 3. . In this way, a single crystal with controlled plane orientation can be formed on an insulator by seedless laser recrystallization.

Effects of the Invention The method of controlling the crystal axis of recrystallized silicon by laser recrystallization of amorphous silicon using polycrystalline silicon on an insulator as a core, according to the present invention, comprises the above-mentioned method. There are no steps during laser recrystallization, and the seed crystal can be easily and arbitrarily formed in any desired location and shape by simply using photomask exposure and ion implantation to form the seed crystal. It is possible to form a crystalline part, has a large degree of freedom in design when actually producing a semiconductor device, and requires only one laser irradiation, which is advantageous in terms of process. Therefore, the present invention greatly contributes particularly to the formation of silicon crystals in large stacked semiconductor integrated circuits and the like.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of a semiconductor substrate showing the crystallization process of an embodiment of the present invention, FIG. 2 is a diagram showing the optical wavelength-absorption coefficient characteristics of single crystal silicon and amorphous silicon, and FIG. 3 is a diagram showing the conventional method. FIG. 4 is a perspective view of a semiconductor substrate showing a two-step laser annealing method, and FIG. 4 is a perspective view of a semiconductor substrate showing a polycrystalline seed laser recrystallization method using a conventional heat sink. 1...Substrate, 2...Insulator, 3...
... Island-shaped polycrystalline silicon, 4 ... Resist,
7... Amorphous part, 3... Polycrystalline part, 6... Laser beam scanning direction. Patent applicant Yuki Iizuka Director of the Agency of Industrial Science and Technology Figure 2 XA XA Figure 3 Figure 4

Claims (1)

[Claims] By forming an island-like thin film of polycrystalline silicon with plane orientation anisotropy on an insulating film and selectively implanting high concentration ions into the polycrystalline silicon, the surface of the ion-implanted portion of the polycrystalline silicon is made amorphous. After that, the polycrystalline silicon is recrystallized using a laser beam under appropriate conditions for the ion-implanted part, so that the ion-implanted part of the polycrystalline silicon is completely melted, and the ions of the polycrystalline silicon are completely melted. The implanted region is brought into a semi-molten state, and the unfused polycrystalline silicon grains in the ion-unimplanted region are used as nuclei for crystal growth to form a single crystal reflecting the plane orientation of the polycrystalline silicon on the insulating film. A method for manufacturing a featured semiconductor device.