JPS60210833A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To enable the formation of a single crystal island of good crystallinity by energy beam inrradiation by a method wherein a recess is formed in part of the insulator on a semiconductor substrate, in which recess a non-single crystal semiconductor island surrounded by an insulator is then formed. CONSTITUTION:An oxide film 22 is formed on the Si single crystal substrate 21. Next, the recess 23 is formed in part of the film 22. Then, a polycrystalline Si 24, an oxide film 25, and a nitride film 26 are formed on the film 22; then, the films 26 and 25 in the part other than the place where a polycrystalline island 27 is to be formed are selectively removed. Thereafter, the Si 24 is removed by half with the mask of films 25 and 26 which have been left, and the island 27 surrounded by the film 22 is obtained by oxidation of the Si 24. The island 27 is recrystallized on fusion by irradiating the island 27 with an Ar laser beam 28 as shown by an arrrow from its one end 27C across the recess 23 to the other end 27B. Therefore, most of the island 27 can be changed to crystal region of good quality.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method for manufacturing a semiconductor device, and a method for manufacturing a substrate for a semiconductor integrated circuit having a multilayer structure, that is, a three-dimensional structure, with high density and high speed.

Conventional Structures and Problems Semiconductor devices have recently become more dense and faster, and there has been an increasing demand for the development of semiconductor integrated circuits with a stacked structure.

Conventionally, to form a semiconductor integrated circuit with a stacked structure, for example, a flat polycrystalline silicon island is formed in an insulator on a semiconductor substrate, and the polycrystalline silicon island is irradiated with an energy beam. This is accomplished by monocrystallizing a silicon island and forming elements on the thus-formed single-crystal silicon island.

A conventional method for forming single crystal islands by energy beam irradiation will be described below with reference to FIG.

First, a CVD oxide film 1 of approximately 1 μm is formed on the surface of the semiconductor substrate 11.
A polycrystalline silicon layer 13 having a thickness of 5 .mu.m is formed thereon by low pressure CVD (FIG. 1a). Next, a protective oxide film 14 and a nitride film 15 are formed, and the nitride film 15 and the protective oxide film 14 are removed by etching in areas other than those where polycrystalline silicon islands are to be formed (FIG. 1b). Using the remaining nitride film 16 and oxide film 14 as a mask, the polycrystalline silicon 13 is etched by half its film thickness to remove it (FIG. 1c). When LOCO8 oxidation is performed, a polycrystalline silicon island 16 is formed. (Figure 1d). An energy beam 17 is irradiated onto the polycrystalline silicon island 16 thus formed.

According to this method, the energy beam 1 shown in FIG.
Recrystallization starts from the interface 18 between the polycrystalline silicon island 16 and the oxide film 12 on the incident side of 7, and a large number of crystals grow at the same time, resulting in many crystal grain boundaries. It was very difficult to make.

Purpose of the Invention In view of the above-mentioned conventional problems, the present invention aims to form high-quality crystal regions by preventing the generation of many grain boundaries due to the simultaneous growth of many crystals caused by energy beam irradiation. The purpose is to provide a high-density, high-speed LSI with a structured structure.

Structure of the Invention The present invention forms a recess in a part of an insulator on a semiconductor substrate, forms a non-single crystal semiconductor island surrounded by an insulator on the insulator including the recess, and forms one of the semiconductor islands. melting and recrystallizing the semiconductor island and improving heat dissipation in the recess by irradiating an energy beam from the end of the semiconductor island across the recess toward the other end of the semiconductor island; This makes it possible to form an element region with good crystallinity and to manufacture high-speed, high-density LSIs.

DESCRIPTION OF EMBODIMENTS A method for forming single crystal islands according to an embodiment of the present invention will be described with reference to FIG. First, for example, a CVD oxide film 22 of about 1 μm is formed on the surface of a silicon single crystal semiconductor substrate 21 . Note that a semiconductor integrated circuit element (not shown) is formed on this semiconductor substrate 21. Next, a part of the CVD oxide film 22 is etched to a depth of 2,000 to 300 m by a method such as etching.
000 recesses 23 are formed (FIG. 2a). The above CV
0.5 μm polycrystalline silicon 24 on the D oxide film 22,
A protective oxide film 25 and a nitride film 26 are formed, and the nitride film and the protective oxide film are selectively etched away at locations other than those where polycrystalline silicon islands 27 are to be formed (FIG. 2b).

Thereafter, using the remaining film 25 and 26 as a mask, half the thickness of the polycrystalline silicon 24 is etched and removed, and the silicon 24 is oxidized with LOCO5 to form a rectangular polycrystalline silicon 24 of 10×100 μm surrounded by the insulating oxide film 22. Crystalline silicon islands 27 are obtained. In addition, silicon 24 in this step
The surrounding oxide film formed by oxidation and the oxide film formed in FIG. 2a are shown as an insulator 22 as an integral part. 2
7A is a region consisting of a part of the polycrystalline silicon island in the recessed portion 23. The thus formed polycrystalline silicon island 27 is irradiated with a continuous wave argon laser 28 as an energy beam in the direction of the arrow from one end 27C of the island 27 across the recess 23 toward the other end 27B.
Island 27 is melted and recrystallized.

According to this method, a large number of crystal growths generated at the interface between the inlet side of the argon laser 28 of the polycrystalline silicon island 27 and the surrounding insulator 22 disappear when they reach the recess 23, and Crystal growth occurs in the crystal orientation generated in the above, and the crystal grows to the exit side (portion 27B) of the argon laser 28 of the polycrystalline silicon island 27.

This is considered to be the reason described below. That is, when the argon laser 28 is incident on one end 27C of the polycrystalline silicon island 27, the polycrystalline silicon begins to melt and crystals grow locally from many parts of the interface between the polycrystalline silicon island 27 and the oxide film 22. occurs. At this time, grain boundaries also occur locally between crystal growth. Then, crystal growth begins to occur from one end of the silicon island, and the beam of the laser 28 reaches the recess 23, causing a region 27 of the island located in the recess.
The silicon in part A begins to melt. At this time, the recess 2
Since the oxide film 22 in the portion 3 is thinner than the other portions, heat dissipation to the underlying semiconductor substrate 21 in the recess 23 is greater than in other portions, and the island region located in the recess 23 is In 27A.

In this case, the solidification of the molten silicon also occurs in other parts (for example, the recess 2).
Faster than polycrystalline silicon (other than 3).

Therefore, the silicon crystal growth that occurs in the concave portion 23 extends toward the end 27B of the polycrystalline silicon island, but the crystal grain boundary that grows in the portion 27C is blocked in the region 27A, which is quickly recrystallized. FIG. 3 shows, in plan, the results of recrystallization when a conventional polycrystalline silicon island and a polycrystalline silicon island according to the present invention are beam annealed under the same conditions. Figure 3a shows a conventional polycrystalline silicon island, and b shows the crystal grain boundaries when a single crystalline silicon island is formed by recrystallizing the polycrystalline silicon island having the structure according to the present invention by laser irradiation. It shows the emergence and disappearance of. First, an argon laser 17 is applied to the conventional polycrystalline silicon island 16 shown in FIG.
When irradiated in the direction of , the polycrystalline silicon island 16 and the insulator 1
A large number of crystals grow simultaneously at the interface 18 with the wafer 2, resulting in a grain boundary 3o, which may extend to the center or the entire island of the recrystallized single crystal silicon island 31, uniformly over the entire surface of the wafer. It was difficult to obtain high quality recrystallized islands.

Next, consider the case where a polycrystalline silicon island having a structure according to the present invention is irradiated with a laser (FIG. 3b).

When the argon laser 28 is irradiated in the direction of the arrow as in the conventional example, the polycrystalline silicon island 2 of FIG.
Crystal growth with different orientations occurs simultaneously at the interface 18 between the insulating film 7 and the insulating film 22, resulting in crystal grain boundaries 30.

Up to this point, the process is the same as the conventional example, but the polycrystalline silicon island 2
Since the recess 23 is formed in the insulator directly under the insulator 7, crystal growth in the recess 23 is faster than crystal growth from the interface 18, so the crystal grain boundaries 30 generated from the interface 18 are formed in the recess 23. By the time the region 27A located in the recess 23 is reached, the silicon region 27A located in the recess 23 has already started to solidify after melting, and the crystal grain boundary 3o generated from the interface has reached the region 27A located in the recess.
blocked at the entrance. Subsequent crystal growth will occur in the concave region 27.
The remaining polycrystalline silicon islands 27B are recrystallized in the orientation generated at A.

As a result, by providing the recess 23, for example, at the end on the incident side of the energy beam, it is possible to reliably make most of the polycrystalline silicon island into a high-quality crystal region.

FIG. 3C illustrates the state of recrystallization due to melting and solidification in the present invention, and when silicon begins to melt in the direction of arrow Because heat dissipation is better in the area 270 than in the area 270, solidification occurs quickly, and grain boundary 30 elongation is similar to area 27A.
It is blocked in the part.

Note that the recess 23 provided in the insulator directly under the polycrystalline silicon island
As shown in FIG. 4, a better crystal region with a larger area can be obtained by providing it on the incident side of the energy beam. The recess 23 may be provided toward the end of the polycrystalline silicon island 27 as shown in FIG. 4a, or may be provided at the interface between the polycrystalline silicon island 27 and the insulator 22 as shown in FIG. Furthermore, as shown in FIG. 5, even if a recess 27 is formed at the bottom of the insulating film 22, the same effect can be obtained by reducing the film thickness of the film 22 in this part and improving the heat dissipation of this part. be able to.

Effects of the Invention According to the present invention, high-quality single-crystal semiconductor islands are formed from polycrystalline or amorphous non-crystalline semiconductor islands, and elements are formed in this single-crystalline region, thereby increasing speed and density. It becomes possible to realize a semiconductor integrated circuit with a laminated structure suitable for.

[Brief explanation of drawings]

1A to 1D are process cross-sectional views showing a conventional method for forming a single crystal silicon island, and FIGS. 2A to 2C are process cross-sectional views showing a method for forming a single crystal silicon island according to an embodiment of the present invention. ,
Figures 3a and 3b are plan views showing the appearance of crystal grain boundaries when conventional polycrystalline silicon and polycrystalline silicon islands according to the present invention are recrystallized by irradiating energy beams, and Figure 3C is a plan view showing the appearance of crystal grain boundaries when the polycrystalline silicon islands according to the present invention are recrystallized. Cross-sectional view showing the state of recrystallization by
, FIG. 5 is a sectional view of another example of a polycrystalline silicon island in the present invention. 21... Semiconductor substrate, 22... Insulator, 23... Concavity, 27... Polycrystalline silicon island, 28... energy beam, 31
・・・・・・Recrystallized single crystal silicon island. Patent applicant: Director of the Agency of Industrial Science and Technology Kawa 1) Hirobe Figure 1 Figure 2vA 9 Figure 3 Figure 4

Claims (1)

[Claims] A recess is formed in a part of an insulator on a semiconductor substrate, a non-single crystal semiconductor island surrounded by an insulator is formed on the insulator including the recess, and a non-single crystal semiconductor island surrounded by an insulator is formed from one end of the semiconductor island onto the recess. A method of manufacturing a semiconductor device, characterized in that the semiconductor island is melted and recrystallized by irradiating an energy beam across the semiconductor island toward the other end of the semiconductor island.