JPS59184517A - Manufacture of lamination-type semiconductor device - Google Patents

Abstract

PURPOSE:To obtain the high-performanc three-dimensional integrated circuit by realizing an island of single-crystal semiconductor in which there is substantially little distortion and defect by a method wherein islands of non-single crystal semiconductor are formed on a surface of an insulator being isolated completely and energy beam is projected to single-crystallize the semiconductor islands and the insulator around said islands excluding the insulator under the bottoms of the islands to form semiconductor elements. CONSTITUTION:CW laser beam 4 is projected onto the islands of non-single crystal semiconductor isolated completely with being scanned in direction of the arrow X so as to single-crystallize the islands 3 of non-single crystal semiconductor. After a non-single crystal silicon layer is formed on a single crystal silicon substrate 1 through an insulator such as SiO2 or Si3N4, SiO2 or the like is buried so as to form islands 3 of non-single crystal silicon isolated completely and surrounded with the insulator 2 such as SiO2 or Si3N4. This islands 3 are then irradiated with laser beam 4. After that, SiO2 21 around the silicon islands 3 are removed, for example by HF buffer solution and a distortion region 31 formed by the irradiation with laser is simultaneously removed. After that, MOS transistors are formed on the recrystallized silicon islands 3, for example, by an usual manufacturing method.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method of manufacturing a stacked semiconductor device generally known as a three-dimensional IC.

Conventional Structures and Problems Many proposals have been made over the past few years regarding a manufacturing method for forming a stacked single crystal in a stacked semiconductor device called three-dimensional XC. Below, we will briefly explain these technologies and point out their problems.

Bridging epitaxy and lateral sheeped beam annealing are well-known crystallization methods using seed crystals. In these methods, crystal growth occurs from an opening in a semiconductor substrate serving as a seed crystal, so the crystal orientation does not change. There are reports that it is easy to obtain good outer crystals while being controlled. However, crystal growth occurs in the periphery of the opening.
The single crystal grows apart in a chrysanthemum-like pattern around the opening 3t,-, making it impossible to obtain a perfect single crystal, and crystal defects and disturbances occur when the crystal grows on the insulating film around the opening. It has been pointed out that it is difficult to increase the area of Q1 due to drawbacks such as easy occurrence.

Furthermore, a graphoepitaxy method is known as a crystallization method that does not use a seed crystal, and several successful examples of single crystal growth from an aqueous solution of KCl have been reported.

However, satisfactory results have not been obtained regarding the crystallization of semiconductor films such as Si, and the technology has not yet become sufficient for fabricating semiconductor devices. Another method for crystallization using seed crystals is a beam annealing method for island-shaped non-single crystals. This method uses an insulating substrate (e.g. SiO
□ or 813N4) using normal semiconductor device manufacturing methods.
By completely insulating and separating a non-single crystal semiconductor island, and then irradiating it with an energy beam (e.g. CW, pulsed laser, electron beam, etc.), crystal islands can be made into single crystals or have large crystal grains. It is a technology that forms Although fairly good single crystal islands have been obtained using this method, since there is no seed crystal, it is difficult to control the crystal nucleation, so it is difficult to control the crystal orientation. At the interface with the surrounding insulator, residual uncrystallized regions and defects due to strain are likely to exist, and furthermore, the optimal beam energy for crystallization changes depending on the shape and size of the island, resulting in uneven crystallization. The problem is that it is possible.

Purpose of the Invention The present invention provides a method for melting and recrystallizing completely insulated non-single crystal semiconductor islands by energy beam irradiation, by removing distortions and defects at the interface between the recrystallized semiconductor and the insulator. By making the relationship between the shape of the recrystallized semiconductor island and the energy beam irradiation uniform, the conventional drawbacks are eliminated and semiconductor islands with excellent crystallinity are formed.
The present invention provides an excellent method for manufacturing a three-dimensional IC stacked semiconductor device.

Structure of the Invention The present invention provides an insulator formed on the surface of a semiconductor substrate 5S in which a semiconductor element is built, and then islands of a non-single crystal semiconductor are formed on the surface of the insulator by, for example, a selective oxidation method or an insulation physical inlay method. After the non-single crystal semiconductor island is melted and recrystallized by energy beam irradiation, insulation is formed around the recrystallized semiconductor island except for the bottom part. After removing the material, a semiconductor element is formed on the recrystallized semiconductor island by a normal semiconductor element manufacturing process. In addition, by forming completely insulating and isolated semiconductor islands with almost the same size and shape, and by making them rectangular in shape, it is possible to further improve the crystallinity of the recrystallized layer and it is convenient for device formation. It is something.

DESCRIPTION OF EMBODIMENTS The manufacturing process of a stacked semiconductor IC according to an embodiment of the present invention will be described with reference to FIG.

(&) in FIG. 1 shows that a CW laser beam 4 is irradiated onto a non-single crystal semiconductor island 3 that is completely insulated and separated while scanning in the direction of the arrow FIG.

6"' A semiconductor element (not shown) is formed on a single crystal silicon substrate 1 through which an insulator such as 5j-0 or Si3N4 is formed by, for example, a low-pressure vapor phase epitaxy method. After forming a single-crystal silicon layer, the bottom surface becomes S by embedding 8102 after selective oxidation or mesa etching.
Insulator 2 such as iO2 or Si3N4, surrounding area is 5i022
A completely insulated and isolated non-single crystal silicon island 3 surrounded by 1 is formed.

FIG. 1(b) is a cross-sectional structural diagram of the silicon island 3 when it is single-crystalized by irradiation with the laser beam 4. In this case, a CWAr laser is used for irradiation with the laser beam 4,
Laser output approximately 18W, beam diameter approximately 80μm, scanning speed 1
m&, the beam scanning overlap is about 30%, the substrate is placed on a vacuum suction stage, and 4 rs O'C
VrC heating. At this time, the width of silicon island 3 is 20μ
m, and each silicon island 3 is completely melted in a certain number of scans by the laser irradiation method described above. 3
1 is a strain region generated at the interface between the silicon island 3 and the surrounding 5iO221 when the silicon island 3 is recrystallized.

7 l' (0) in FIG. 1 is a cross-sectional structural diagram when the peripheral 5iO221 of the silicon island 3 is removed by, for example, an HF buffer solution after laser irradiation, and the strained region 31 formed by the laser irradiation is removed. can also be removed at the same time.

After this, heat treatment may be applied to remove defects, distortions, etc. generated during recrystallization.

FIG. 1(d) is a cross-sectional structural diagram when a MOS transistor is subsequently formed on the recrystallized silicon island 3 by, for example, a normal MO8 element manufacturing method.

51 is a source and drain region having a conductivity type opposite to that of the island 3;
2 is a gate electrode formed through an insulating film 53, 54 is a wiring insulation isolation part 5102, and 55 is a wiring metal. The MO8 element thus formed exhibits very excellent characteristics because it is built into the single crystal silicon island 3, which has almost all the distortions and defects.

When the polycrystalline silicon island 3 is recrystallized into a single crystal by laser irradiation, for example, the shape of the polycrystalline silicon island 3,
The optimal laser irradiation conditions for crystallization vary slightly depending on the size. The concept of this situation will be explained with reference to FIG.

When there are two types of polycrystalline silicon islands 3 (A, B, C, D) with respect to the beam diameter of the laser 4 in the scanning direction For example, about 80 inches of beam diameter,
When the silicon islands B and C] are approximately twice the beam diameter of the laser 4, the laser 4 is scanned in the X direction as shown in FIG. 2(a). As shown in FIG. 2(b), after the first beam scan, A of the silicon island 3 is completely melted and recrystallized in this one scan, becoming a single crystal. At 3 B, the beam 4 melts only about half of the island, so many fine microcrystals grow in the laser irradiated area using the polycrystalline silicon in the non-laser irradiated area of the silicon island 30B as seeds. I end up.

After the next laser scan, as shown in FIG. 2C, the 30 silicon islands are not irradiated with the laser, so they remain as single crystals formed in the first scan. In B of silicon island 3, approximately half of the area including the unirradiated area is melted by the first laser scan, but as a whole, some parts overlap between the first and second laser irradiation. Although the crystals are irradiated, they are recrystallized separately, resulting in agglomerations of small crystal grains. At this time, C and D of the silicon island 3 remain unirradiated with the laser.

As shown in FIG. 2(d), at the end of the fourth laser irradiation scan, the silicon island 3 has narrow widths A and D.
In contrast, in B and C, where the width of the silicon island 3 is wide, the entire island is almost a single crystal, whereas the island is made up of an aggregate of fine crystal grains.

Therefore, in the method described in FIG.
is created.

Furthermore, the way in which strains or defects occur in recrystallized silicon islands during recrystallization differs depending on the shape and size of the islands. The removal method will need to be changed depending on the shape and size of the island. For example, islands A of different sizes in Figure 2.

1o/ Regarding B, strain after recrystallization by laser irradiation.

An overview of how defects are introduced and the crystallinity after their removal by etching will be explained with reference to FIG.

(al in FIG. 3) is the strain introduced into the recrystallized islands A and B after laser irradiation shown in (1) in FIG. This is a conceptual diagram of a grain boundary (indicated by a solid line inside the island).In the narrow island A shown in [1], the entire island is almost single crystal, but the area where distortion and defects occur at the periphery has a coefficient of thermal expansion. It becomes wider due to the large amount of stress that is applied due to differences in

On the other hand, in the case of the 11 wide islands B, the strain and defect areas at the periphery are small, but as mentioned above, the entire island becomes an aggregation of small crystal grains, and at the same time, the overlap of the laser scans in the central part of the island B Distortions and defects occur in the parts. Therefore, as shown in (bl) of FIG. 3, even if etching is performed to remove the strained area around island B, the strain and defects will remain around island A.

Furthermore, as shown in (0) in Figure 3, if all the peripheral distortion of island A is removed, the peripheral parts of both islands A and B become distorted.

11P2 The defect can be removed, but in this case, the remaining island A will be too narrow in width, and the defective area in the center of island B will remain.

Of course, the above problem can be solved by increasing the laser beam diameter so that islands B and C are completely melted in one scan, but generally speaking, if the laser beam diameter is increased, the central part of the beam will melt. Since the power density becomes large, the energy density on the narrow islands A and D is too large and the silicon melts and scatters or evaporates to the surrounding area, causing silicon to be lost from part or all of the islands. I don't like what you end up doing. Therefore, silicon islands formed on the same substrate have almost the same shape.

It is desirable to have a large size. In view of this, some preferred embodiments in which silicon islands are formed are shown below.

In FIG. 4, (al) is formed by arranging all the polycrystalline silicon islands 3 in a square shape at regular intervals, and the size of the side is 20%.
This is a case where a laser 4 having a relatively large beam diameter is scanned and irradiated in the X direction so that the center of the beam passes near the center of the island. Figure 4(b) shows silicon islands formed by tilting squares of the same size at a 45° angle and arranging them at regular intervals.
This is a case in which laser irradiation is performed so that each silicon island is melted by laser irradiation in multiple scans. FC) in Fig. 4 is a silicon island 3 formed by arranging rectangles of the same size at regular intervals.The short side of the rectangle is slightly smaller than the beam diameter of the laser 4, and the long side is The length in this case is, for example, five times the length of the short side, and the scanning direction of the beam of the laser 4 is set to be parallel to the long side of the rectangle, and the scanning position is set to be in the middle of the rectangle.

By making the size and shape of the silicon islands 3 almost the same as in the three examples above, and appropriately setting the scanning direction and position of the beam, it was possible to make the entire island of each island a single crystal. .

Next, an embodiment in which a single-crystal silicon island obtained by recrystallization as described above is used as a substrate for forming an element will be described with reference to FIGS.

Figure 5 (+!L) is 20 surrounded by Sin,,21
11m x 13 l-” 100μm rectangular polycrystalline silicon island 3 with beam diameter 3
FIG. 3 is a conceptual plan view when scanning with a 0 μm laser in the X direction. At this time, the polycrystalline silicon island 3 is completely melted by one beam scan and becomes a single crystal island. FIG. 6(b) is a cross-sectional structural diagram after recrystallization. Single crystal silicon island 3
A defective region 31 due to strain generated during recrystallization is present at the boundary between the wafer and the surrounding sio, 21. After laser irradiation, the peripheral sio□ 21 is removed to remove distortion, and the state is shown in (C1) in FIG.

Further, as shown in FIG. 5(d), the surface portion of the single-crystal silicon island 3 is removed, and then the island 3' is divided by etching into a size suitable for forming a device, for example, 158 m x 30 μm. And so.

After that, CVD is applied between the divided single crystal silicon islands 3'.
The surface was planarized by filling with, for example, SiO□22 (FIG. 5(e)), and semiconductor elements were formed on the divided single-crystal silicon islands 3'.

In addition, in FIG. 6 (at is a single crystal 14) after forming a plurality of polycrystalline silicon islands 3 of a size suitable for element formation, complete melting and recrystallization is performed with one scan of the laser 4. It is a conceptual plan view of crystallization. FIG. 6(b) is a cross-sectional structural view after laser irradiation, and there are distortions and defect areas 31. Next, the single crystal silicon island 3 and the surrounding area 5in221
The boundary area including the distortion and defect area 31 is removed by etching. The conceptual plan view and cross-sectional structure diagram at this time are shown in Figure 6 (C
1 and (d), respectively. Elements are formed on the monocrystalline silicon island 3 thus obtained.

In the present invention, an electron beam, an infrared beam, etc. may be used in addition to a laser.

Effects of the Invention As is clear from the above explanation, the present invention makes it possible to realize a high-quality single crystal semiconductor island of a desired size with very few distortions and defects, and to provide a high-performance three-dimensional IC. .

[Brief explanation of drawings]

FIG. 1 is a process diagram showing an embodiment of the present invention for producing single crystallized islands by laser irradiation, in which (a) is a conceptual plan view of laser irradiation, and (bl, (c), and (d) are cross-sectional structural diagrams). , Figure 2 (at, (b), (cl, (d)) is
Conceptual plan view showing the difference in recrystallization depending on the size of the island and the 151-z size of the laser beam, Figure 3 (a), (b), (cl depends on the size of the recrystallized island) Conceptual diagram showing the difference in the way distortion and defects are introduced, Figure 4 (al, (bl, (bl), (plan conceptual diagram showing an example of laser irradiation when the size, shape, and arrangement of clit islands are the same, FIG. 5 is a process diagram of an example in which single crystallized islands are formed and then divided into desired sizes.
(a) is a conceptual plan view, (b), FC+, (d
), (1111 is a cross-sectional structural diagram, FIG. 6 is a process diagram of an example of removing the boundary with the periphery 5102 of the single crystallized island, (a) and (c) are conceptual plan views, (b)
1, (d) is a cross-sectional structural diagram. 1... Base single crystal silicon substrate, 2...
・Base F11 FfI Collar t? Figure 1 Figure 1 Figure 2 Figure 2 DD Figure 3 Figure 4 Figure 2/ Figure 4 Figure 60.

Claims (3)

[Claims] (1) A step of forming a completely insulated non-single crystal semiconductor island on the surface of a semiconductor substrate, a step of crystallizing the non-single crystal semiconductor island by irradiating the island with an energy beam, and a step of crystallizing the non-single crystal semiconductor island. 1. A method for manufacturing a stacked semiconductor device, comprising the steps of: removing an insulator around the island except for the bottom surface of the island; and forming a semiconductor element on the crystallized semiconductor island. (2) The stacked semiconductor device according to claim 1, characterized in that, at the same time as removing the insulator, the surrounding uncrystallized region other than the bottom part of the crystallized semiconductor island is removed. Production method. (3) A stacked semiconductor device according to claim 1, characterized in that a plurality of completely insulated and isolated non-single crystal semiconductor islands are formed with substantially the same diameter and shape. Production method. 2. The method for manufacturing a stacked semiconductor device according to claim 1, wherein the island of the completely insulated non-single crystal semiconductor has a rectangular shape.