JPS6151821A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To provide a single crystal semiconductor layer with better quality without melting semiconductor seeds, by coating an amorphous semiconductor layer with a low melting point, on a single crystal semiconductor seeds, and by annealing the amorphous semiconductor layer by low power beams to make it single crystal. CONSTITUTION:On an SiO2 film substrate 2, 4 buried in a single crystal silicon film 3 having an island shape, an amorphous silicon layer 15 is coated with an evaporation or plasma CVD method. By scanning continuous argon laser beams, the amorphous silicon film is heated and melted to be converted to a single crystal silicon film 15. Even with the laser output reduced, the amorphous silicon film can be melted and therefore the single crystal silicon film 15 in the same crystal orientation as the single crystalline silicon film 3 being silicon seeds is formed, with the result that the single crystal silicon with extreamly good quality can be laminated in multi-level.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for manufacturing a semiconductor device, and particularly to a method for forming a single crystal semiconductor layer in an SOI structure semiconductor device.

Semiconductor construction circuits (ICs) are LSI, VLSI, and two-dimensional (
Although miniaturization and high integration have been achieved in the (planar) area, there is a limit to this miniaturization, and three-dimensional LSIs that are stacked three-dimensionally are currently being used as a means to further increase the integration.
is shown in close-up.

The basis of such three-dimensional LSI is So1
It is a semiconductor device with a (Silicon On IrHsulator) structure, and it is a method of depositing a non-single-crystalline semiconductor layer on an insulating substrate, converting it into a single crystal by beam annealing, and forming a device on the single-crystal semiconductor layer. Yotsu
・It has been created.

Although such semiconductor elements are stacked in multiple layers via insulating films to form a three-dimensional LSI, semiconductor elements with this SOI structure cannot be formed on a conventional semiconductor substrate. Compared to semiconductor devices, they have the advantage of higher integration and higher performance.

For example, when forming an LC made of CMO3 elements, since the semiconductor region is located on the insulating ridge, there is no need to worry about launch-up from a characteristic point of view, and furthermore, a channel stopper is not required, which further improves the degree of integration.

But 1. The step of performing single crystallization by beam annealing is particularly important from the viewpoint of crystal quality, and it is desirable to form a single crystal semiconductor layer (semiconductor film) of as high quality as possible.

[Prior Art] Now, to explain a conventional method for forming a single crystal semiconductor film on an insulating film, FIGS. 2A to 2D show cross-sectional views in the order of steps. First, as shown in the same figure (al), silicon dioxide (S
i02) H'A 2 is formed, and a polycrystalline silicon film 3 is deposited thereon by chemical vapor deposition (CVD).

Next, as shown in FIG. 2 (bl), a continuous argon laser (CW-Ar La
5er) The polycrystalline silicon film is transformed into a single-crystalline silicon film 3 by scanning the beam (f) to heat and melt the polycrystalline silicon film (this is beam annealing (this example is laser annealing)), and then the silicon substrate 1 The portion of the single crystal silicon film in contact with is selectively oxidized to produce a SiO2 film 4. In this case, a silicon nitride film, for example, is used as an oxidation prevention mask (not shown) for selective oxidation.

Then, the S which buried the island-shaped single crystal silicon film 3
An i O2 film substrate (insulating film substrate) 2.4 is formed, and then, as shown in FIG. 2 (C1), a polycrystalline silicon film 5 is again deposited thereon by the CVD method.

Next, as shown in FIG. 2(d), laser annealing is performed again to transform the polycrystalline silicon film into single crystal silicon H moxibustion 5.

In this way, a single-crystal semiconductor film can be formed on the insulating film substrate, and the semiconductor element formed on this single-crystal semiconductor film has higher performance, and the overall speed of the IC can be increased.

[Problems to be Solved by the Invention] Incidentally, in the single crystallization process described above, in the initial laser annealing process for forming the single crystal silicon film 3, the single crystal seed portion is the silicon substrate 1 itself. In this structure, heat is easily dissipated from the silicon substrate l, which has good thermal conductivity. Therefore, during the process of melting the silicon film by laser annealing, the single-crystal seed portion is cooled quickly, and /8 melting of the seed does not occur. for that,
High quality single crystal silicon MF! 3 can be formed.

However, on the other hand, in the next laser annealing process to form the single crystal silicon film 5, since the single crystal seed portion is the single crystal silicon film 3 liberated by the 5i02 films 2 and 4, which have poor thermal conductivity, the laser annealing While melting the H odor, the single crystal seed portion is likely to be melted, making it impossible to form a single crystal, or there is a high possibility that a poor quality crystalline silicon film will be formed.

The present invention proposes a method of forming a single crystal silicon film with good crystal quality in a laser annealing process for a non-single crystal silicon film deposited on the second insulating film substrate.

[Means for Solving the Problem] The problem is to deposit an amorphous semiconductor layer M on an insulating substrate provided with a single crystal semiconductor seed, and beam annealing the amorphous semiconductor layer to form the single crystal semiconductor. This is achieved by a method for manufacturing a semiconductor device in which a single crystal semiconductor layer is formed along the crystal orientation of a seed.

[Operation] That is, an amorphous semiconductor layer having a melting point lower than that of the semiconductor seed is deposited on a single crystal semiconductor seed, and the amorphous semiconductor layer is melted and made into a single crystal by low power beam annealing.

In this way, a high quality single crystal semiconductor layer can be obtained without melting the semiconductor seed.

[Example] An embodiment will be described in detail below with reference to one drawing.

7fl Figure 1 (al, (bl) shows sequential cross-sectional views of the forming process according to the present invention, and this figure is similar to the conventional Figure 2 (C1,
(This is a process sectional view according to the present invention corresponding to the process sectional view shown in d+.

That is, as explained in FIG. 2 (bl), the 5i02 film substrates 2 and 4 in which the island-shaped single crystal silicon film 3 is buried are formed, and as shown in FIG. Film thickness 4
Vaporize an amorphous silicon layer of 15,000 people.

It is deposited by a deposition method or a plasma CVD method.

In this case, the island-like region of single crystal silicon l18%i3 is
For example, area 10. This island-like area is formed in a mesh shape (checkerboard pattern) with a size of czm square and a film thickness of 4,000 people.

Next, as shown in FIG. 1 (bl), a continuous argon laser beam is scanned to heat and melt the amorphous silicon film to transform it into single crystal silicon 115ti15.

At that time, the annealing conditions were to heat the insulating film substrate to about 450℃, laser output to 6W, and beam spot diameter to 30 to 50℃.
μmφ, and the scanning speed is set to lQcm/sec.

In this way, even if the laser output is reduced to 6 W, the amorphous silicon film is melted and a single crystal silicon film 15 is formed along the crystal orientation of the single crystal silicon film 3 as a silicon seed. The melting point of single crystal silicon is 1400°C, while the melting point of amorphous silicon is 950°C.
This is because it is low.

On the other hand, in the initial laser annealing process for converting a polycrystalline silicon film into a single crystal, the laser output is scanned at IOW or higher output to melt the polycrystalline silicon film, with other annealing conditions being the same. There is.

Therefore, when the laser output is 6 W, the single crystal silicon seed is not melted, and only the amorphous silicon is melted with low energy, forming the single crystal silicon film 15 along the silicon seed.

In this way, monocrystalline silicon of infinitely high quality can be stacked three-dimensionally.

[Effects of the Invention] As is clear from the above description of the embodiments, according to the present invention, in the method for manufacturing a three-dimensional LSI, single-crystal silicon layers with good crystal quality can be easily stacked, and the high performance of the three-dimensional LSI can be improved. This greatly contributes to improved quality and improved quality.

[Brief explanation of drawings]

Figure 1 (al, (b1) is a step-by-step sectional view for explaining the forming method according to the present invention, Figure 2 (al~(d+ is a process sectional view for explaining the forming method of one conventional example) In the figure, 1 is a silicon substrate, 2.4 is a SiO2 film, 3.5 is a polycrystalline silicon film or a single crystal silicon film, and 15 is an amorphous silicon film or a single crystal silicon film. 1st σ 2nd figure

Claims (1)

[Claims] An amorphous semiconductor layer is deposited on an insulating substrate provided with a single crystal semiconductor seed, and the amorphous semiconductor layer is beam annealed to form a single crystal semiconductor layer along the crystal orientation of the single crystal semiconductor seed. A method for manufacturing a semiconductor device, characterized in that: