JPS63281418A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To make it possible to use a wafer having an orientation flat of the direction <110> by patterning an insulating film in a specific direction, and working a seed crystal into a recessed L-like shape or a combination thereof. CONSTITUTION:On an insulating film 2 patterned in parallel with the direction <110> 3, amorphous Si is deposited, which is heated to about 600 deg.C, forming a seed crystal into a recessed L-like shape. With this, the amorphous Si layer shows a fast crystal growth in the direction <100> 4 with a seed crystal part 1 of the substrate as the starting point. At this time, different from the previous case that the growth was made on a SiO2 pattern parallel with the direction <100>, there is no introduction of twir or transition onto the single crystal, whereby a good crystal can grow.

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention relates to a method for manufacturing a semiconductor device, and in particular to a method for manufacturing a semiconductor device.
The present invention relates to a manufacturing method using solid phase epitaxial growth of a (Silicon on In5ulator) structure.

[Conventional technology]

In recent years, S
OI (Silicon on In5ulator)
The structure is attracting attention. In other words, there have been reports of attempts to reduce junction capacitance and increase speed by providing an insulating layer such as 5iOz below the source/drain of the MOSFET, and to stack an active layer on top of the insulating film to achieve three-dimensional integration. has been done.

There are various methods for forming an SOI structure, but among them, a solid phase epitaxial growth method of amorphous Si is considered to be promising from the viewpoint of lowering the process temperature and mass productivity. As shown in FIG. 2, this is done by providing an opening in the Si substrate 21 covered with the insulating film 2 so that the seed crystal 1 is exposed, and then depositing the amorphous 5i22 and heat-treating it. This is a method to obtain an SOI structure by performing solid phase epitaxial growth in the vertical and horizontal directions.

In solid-phase epitaxial growth, the growth rate and quality of the obtained crystal vary greatly depending on the direction of crystal growth.
100) direction is considered the most desirable. For this reason, a Si substrate with a plane orientation (IOO) is used, and as shown in FIG. 3(a), the insulating film 2 is
A method of patterning in the > direction is often used.

Furthermore, when prototyping devices on the SOI layer, the third
An example using an island-like region of an insulating film patterned in the <100> direction as shown in FIG. 2(b) has been reported.

(IEICE Technical Research Report Vol. 1.86Na 156
．． P103) [Problems to be Solved by the Invention] However, the method using an insulating film patterned in the <100> direction has several problems as described below.

In particular, when using the island-like structure shown in Figure 3(b), planar defects due to mismatching of the growth tips remain (Figure 3(C)), except in the case of square islands. However, forming an element in this portion may cause leakage current or the like.

Further, when patterning is performed in the <100> direction, it is desirable to change the orientation flat of the wafer to the <100> direction in order to facilitate pattern formation. However, in that case, the chip will be scribed in the <100> direction, and the 110
In the > direction, it becomes necessary to use a method with a relatively high cost.

An object of the present invention is to form a single crystal layer with few defects on an island-like insulating film, and to use a wafer having an orientation flat in the <110> direction.
An object of the present invention is to provide a method for forming an OI structure.

[Means for solving problems]

The above purpose is to pattern the insulating film in the <110> direction and process the seed crystal into a concave L-shape (Fig. 1 (a)) or a combination thereof (Fig. 1 (b), (c)). This is achieved by FIG. 1(c) corresponds to the case of an island-shaped insulating film.

To explain this point in more detail, as shown in FIG. 1(a), amorphous Si is deposited on the insulating film 2 patterned in parallel to the <110> direction 3 and heated to about 600°C. As a result, the amorphous Si layer exhibits rapid crystal growth in the <100> direction 4 starting from the seed crystal portion 1 of the substrate. At this time, the conventional S i 02 pattern parallel to the <100> direction (IEICE).

Unlike when grown on a single crystal (ED-86-78), no twists or dislocations are introduced onto the single crystal, and a good crystal can be grown.

[Effect]

The present invention is based on the discovery of the fundamental mechanism in Si crystal growth. In other words, in the process of crystal growth from a seed crystal, in the case of a convex seed crystal, the slow-growing surface expands, whereas in the case of a concave seed crystal, the fast-growing surface expands. I found out.

FIG. 4(a) shows that in a convex seed crystal composed of (100) and (110) planes, the (110) plane or a plane with a slower crystal growth rate expands. (b) shows how the surface with a fast growth rate expands in a concave seed crystal. For solid-phase epitaxial growth of Si, the Drosd-Vashbarn model (J,
APPl, Phys.

53 (1), Jan, (1982), 397)
is considered to be reasonable, and it is possible to support the above fact using this model. Figure 5(a).

(b) represents the atomic model corresponding to FIGS. 4(a) and (b), respectively. In the figure, black circles represent atoms in the crystal, and white circles represent atoms in amorphous Si.

The black circles on the amorphous Si side from the initial interface are Drosd
-Means an atom that satisfies Washbarn's condition and is crystallized. From this figure, we can see that for the convex seed crystal ((,)
) explains that the slow-growing (110) plane expands, and in the case of a concave seed crystal ((b)), the fast-growing (100) plane expands.

By the above mechanism, as shown in FIG. 1(a), the insulating film 2
by patterning the seed crystal in the <110> direction 3 to form a concave L.
If it is shaped like a letter, the growth occurs fastest in the <100> direction despite patterning in the <110> direction, and the crystallinity is excellent. FIGS. 2(b) and 2(c) show a combination of L-shaped structures, and in particular, in FIG. 2(c), it is possible to form a high-quality SOX layer without planar defects on the island-shaped insulating film.

〔Example〕

[Example 1] First, an example in which a MOS transistor having the structure shown in FIG. 6 is formed will be described.

After thermally oxidizing a czp type Si substrate 61 with a resistance of 10 Ωcm and a (100) plane orientation flat <110> direction to form a 200 nm thick 5iOz film 61 on the surface,
This was patterned in the <110> direction to a length of 10 μm.
It was processed into an island shape with m1 width of 4 μm. After boiling in nitric acid and cleaning with hydrofluoric acid, it was placed in an ultra-high vacuum apparatus, and the surface was cleaned by Ar beam scattering and heat treatment at 680°C. 5iOz
The film was thereby reduced to 150 nm. Thereafter, an amorphous Si film was deposited to a thickness of about 1 μm at a deposition rate of 6 people/s, and
℃, after heat treatment in vacuum for 1 hour, in an electric furnace at 600℃
, heat treatment was performed for 7 hours to grow crystals. Subsequently, B ions were implanted at 125 KeV and LXl 018 cm-'' to dope the SOI layer 62, and then a transistor was formed by a normal MO3FET formation process.

FIG. 7(a) shows the drain voltage-drain current characteristics of the formed MoS transistor, which were investigated by varying the gate voltage. The field effect mobility calculated from the saturation region was approximately 360 cm"/V-8, which was good. Figure 7 (b)
The leakage current between the source and drain determined from the subthreshold characteristics shown in ) is less than 10-unit OA, which is improved from the conventional reported example. This is the source
This effect is thought to be due to the absence of planar defects between the drains.

[Example 2] Next, an example in which a MOS transistor having the structure shown in FIG. 8(a) is formed will be described.

SiO was formed by thermally oxidizing a Si substrate in the same manner as in Example 1.
The x film 61 was processed into a 2 μm square pattern. This substrate was subjected to the same treatment as in Example 1 to perform crystal growth and As doping.

Subsequently, the crystal between the 5i02 films 61 was etched to provide a gate electrode 681. After forming a gate oxide film by thermal oxidation, an AQ gate electrode 82 was deposited, and the surface was planarized by an etch-back method. Other processes are the same as in Example 1.

In this structure, 5iO
Since the junction capacitance can be reduced by the z film and AQ can be used as the gate electrode material, high-speed operation of the transistor is possible.

[Embodiment 3] Next, an example in which the dynamic memory cell shown in FIG. 9 was created will be described.

After forming an n-type buried layer 91 by As implantation, surface oxidation and SiO2 film patterning, solid phase epitaxial growth was performed in the same manner as in Example 1.

Thereafter, an opening 93 is formed on the n buried layer, and a gate and capacitor insulating film 92 is formed by thermal oxidation.
Subsequently, a PolySi gate 63 was deposited. Thereafter, memory cells were formed according to normal processes.

According to this method, the MOS transistor is formed into an SOI structure to increase the speed, and by using a capacitor insulating film having a folded-over structure, the capacitor area can be expanded and the storage capacitance can be increased.

〔Effect of the invention〕

According to the present invention, a single crystal layer with few defects can be formed on an island-shaped insulating film, and an SOI structure can be easily formed even using a wafer having an orientation flat in the <110> direction. It is.

[Brief explanation of drawings]

Fig. 1 is a plan view showing the basic structure of the present invention, Fig. 2 is a diagram for explaining the principle of solid phase epitaxial growth, and Fig. 3 is a plan view showing the basic structure of the present invention.
The figure is a diagram for explaining a clear example for explaining a conventional technique. DESCRIPTION OF SYMBOLS 1... Seed crystal, 2... Insulating film, 3... <110>
direction, 4...<100> direction.

Claims (1)

[Claims] 1. SOI (Sili) using solid phase epitaxial growth
1. A method for manufacturing a semiconductor device, characterized in that the insulating film is patterned in the {110} direction, and the seed crystal is shaped into a concave L-shape or a combination thereof.