JPS62143442A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To form fine element isolations and to contrive an increase in the integration and density of an IC by epitaxially growing second semiconductor crystal layers selectively on the exposed insulating substrate except a first semiconductor crystal layers. CONSTITUTION:An Si single crystal layer (first semiconductor crystal layer) 12 is epitaxially grown on a substrate 11. The surface of the crystal layer 12 is oxidized to form a thin SiO2 and a (SiO2+Si3N4) film 13 is formed thereon. The film 13 is selectively etched and the films 13 are coated only on the crystal layer 12 at desired regions. The crystal layer 12 is selectively etched away using the films 13 as masks. A heating is performed in an oxidizing atmosphere and SiO2 films 14 are formed on the side surfaces of each crystal layer 12. Si single crystal layers 15 are epitaxially grown selectively on the exposed parts of the substrate 11. Lastly, the masks of the films 13 are removed. Thereby, the fine element isolations are formed and an increase in the integration and density of the IC is attained.

Description

[Detailed Description of the Invention] [Summary] A first semiconductor crystal layer is epitaxially grown on an insulating substrate on which a semiconductor crystal layer can be grown epitaxially, and then the semiconductor crystal layer is selectively removed, and then the remaining semiconductor is removed. An insulating film is formed on the side surface of the crystal layer, and then a second semiconductor crystal layer is selectively epitaxially grown on the removed portion.

In this way, an element isolation band made of a fine insulating film is formed.

[Industrial Application Field] The present invention relates to a method of manufacturing a semiconductor device, and particularly to a method of forming an isolated single crystal semiconductor layer in an SOI structure semiconductor device.

As demand for semiconductor integrated circuits (IC) increases, LSI,
It has been highly miniaturized and highly integrated compared to VLSI, because the higher the integration, the higher the performance.

On the other hand, ICs generally have a large number of semiconductor elements formed on a semiconductor substrate itself such as silicon, but another method is SOI (Silicon Insul), in which a semiconductor crystal layer is epitaxially grown on an insulating substrate.
A method is known in which a semiconductor crystal layer is grown on an insulating substrate using an insulating material that allows epitaxial growth of a semiconductor crystal layer, and a semiconductor element is formed in the semiconductor crystal layer. ICs with such a structure have advantages such as low parasitic capacitance and high speed.
The OS (Silicon On 5apphire) structure is a typical example.

However, even in such a Sol structure, it is natural that it is desirable to increase the integration as much as possible.

[Problems to be solved by conventional technology and invention] Now,
In addition to the above-mentioned sapphire substrate, a magnetic spinel (MgO.A1203) substrate is known as an insulating material on which a semiconductor crystal layer can be grown epitaxially, and all of them are crystalline substrates.

By the way, an IC is formed on a semiconductor crystal layer on such an insulating substrate.
When forming a semiconductor device, element isolation (isolatton) is required to electrically insulate between semiconductor elements.

However, the element isolation methods conventionally implemented in the SOI structure are insulating film isolation by the LOCO8 method or trench isolation, as in the case of ordinary semiconductor substrates. Figure 2 shows a Sol structure semiconductor substrate separated by an insulating film by the LOCO3 method, 1 is a magnetic spinel substrate,
2 is a silicon single crystal layer, 3 is silicon oxide (SiO2)
As is well known, the film is formed by forming a silicon single crystal layer 2 and then selectively oxidizing it to form a 5i02 film 3. The silicon single crystal layer 2 becomes a semiconductor element formation region, and the 5i02 film 3 becomes a separation zone.

Furthermore, Fig. 3 shows the trench isolation method, in which 1 is a magnetic spinel substrate, 2 is a silicon single crystal layer, 4 is a trench isolation zone, and the trench isolation zone 4 is formed by forming a 5i02 film on the surface inside the trench. It is an isolated structure in which a polycrystalline silicon film or the like is buried.

The above method is the same element isolation method as for general semiconductor substrates, but as a separation method specific to insulating substrates, as shown in FIGS. An insulating film 5 is selectively deposited on the
), and then selectively epitaxially grows on the exposed substrate (2) to form a silicon single crystal layer 2 (see FIG. 3(b)).

However, with these separation methods, it is difficult to form device isolation bands finely. For example, when growing a silicon single crystal layer 2 with a thickness of about 2 μm, the minimum separation width is about 1 μm, no matter how fine it is. In practice, the separation band width is about 2 μm, and it is difficult to form a separation band with a finer width than that.

The present invention proposes a method of forming element isolation bands in such an SOI structure to further miniaturize them.

[Means for solving the problem] The problem is to form a first semiconductor layer on an island paper whose surface and side surfaces are covered with an insulating film on an insulating substrate on which a semiconductor crystal layer can be grown epitaxially, and then This problem can be solved by a method for manufacturing a semiconductor device that includes a step of selectively epitaxially growing a second semiconductor crystal layer on the exposed insulating substrate other than the first semiconductor crystal layer.

[In other words, the present invention epitaxially grows a first semiconductor crystal layer on an insulating substrate capable of epitaxial growth, then selectively removes the semiconductor crystal layer, and then removes the side surface of the remaining semiconductor crystal layer. An insulating film is formed on the
A second semiconductor crystal layer is selectively epitaxially grown on the removed portion of the first semiconductor crystal layer.

In this way, a fine element isolation band made of an insulating film formed on the side surface of the first semiconductor crystal layer is formed.

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

FIGS. 1(a) to 1(el) show step-by-step cross-sectional views of the formation method according to the present invention. First, as shown in FIG. (first semiconductor crystal layer) is epitaxially grown. The growth method is to grow by heating the substrate 11 to around 1000° C. and feeding silicon tetrachloride (SiC+4) gas thereon to decompose it. Then, a silicon single crystal layer 12 is formed along the crystal direction of the magnetic spinel substrate 11.

Next, as shown in FIG. 1 (bl), the surface of the silicon single crystal layer 12 is oxidized to form a thin 5i02 film, and silicon nitride (Si3
N4) 5i02 with a film thickness of about 2000
An oxidation-resistant and etching-resistant film consisting of the film + Si3N4 film 13 is formed, and a resist film pattern (not shown) is formed on it.
5i02 film + Si3 N413 selectively using a mask
5i02 film+Si3N4 film 13 is coated only on the silicon single crystal layer 12 in a desired region.

Next, as shown in FIG. 1 (C1), 5i02 film + Si
3 Using the N4 film 13 as a mask, the exposed silicon single crystal layer 12 is selectively etched away using a mixed gas of CF4 and 02 or by active ion etching (RIE).

Next, as shown in FIG. 1(d), the silicon single crystal layer 12 is heated to about 900° C. in an oxidizing atmosphere and coated with a mask to form a film with a thickness of 2000 to 2000° C. on the side surface (exposed portion) of the remaining silicon single crystal layer 12.
4000 5i02 films 14 are formed.

Next, as shown in FIG. 1 (el), the silicon single crystal layer 12 is etched away by heating it again to around 100° C. and introducing silicon tetrachloride (SiCI4) or dichlorosilane (SiH2C12) gas to decompose it. A silicon single crystal layer 15 (second semiconductor crystal layer) is selectively epitaxially grown on the exposed portion of the magnetic spinel substrate 1, and finally, a 5i02 film + Si3N4 film 13 is grown.
remove the mask. At this time, 5iC14 or 5iH2C
When a chlorine-based gas such as I2 is used, oxides (St O
Silicon can be selectively grown only on a crystal substrate such as the magnetic spinel substrate 11 without growing silicon on the □ film + Si3N4 film 13 mask).

In the following steps, a semiconductor element is formed in the exposed silicon single crystal layer 12.15.

Note that in the above-described forming method, the silicon single crystal layer 12.
In order to form 15 in the n-type silicon layer, arsenic ions may be implanted into the entire surface at the end of the above process. In addition, when forming 0MO5IC etc. by making one silicon single crystal layer 7112 n-type and the other silicon single crystal layer 15 p-type, the step before growing the silicon single crystal layer 12 and covering the mask. Then implant arsenic ions into the entire surface to make it n-type.
Next, after growing the silicon single crystal JW15, boron ions are implanted to make it p-type in a step before removing the mask.

If formed as described above, the element isolation band can be miniaturized to the order of submicrons, and the IC can be further highly integrated.

[Effect of the invention] As is clear from the above explanation, according to the present invention, SOI
In the method of manufacturing a structural IC, fine element isolation can be formed, which greatly contributes to high integration and high density of ICs.

[Brief explanation of drawings]

FIGS. 1(a) to (e) are cross-sectional views of the forming method according to the present invention in the order of formation steps, FIGS. 2, 3, and 4 (at, bl are cross-sectional views of conventional element isolation, , are cross-sectional views in the order of formation. In the figure, 1.11 is a magnetic spinel substrate, 2 is a silicon single crystal layer, 3', 4.5 is a conventional element isolation band, and 12 is a silicon single crystal N (first semiconductor crystal N), 13 is 5i02
f! ! +5taN4 film (oxidation resistant/etching resistant film), 14 is 5i02 film (insulating film/device isolation band of the present invention) 15
indicates a silicon single crystal layer (second semiconductor crystal layer). Honga Akashi 9.3 points practice 1 house p tr 1 side mm III 1 mackerel, line carpet ga sho ne T side face g12 Inayashi f/I tε〉10zui skin thi unfinished expression hka Figure No. 3 Figure Attack Table □w# %” x-ne L・0 Oki Super@4 Figure

Claims (1)

[Claims] A first semiconductor layer whose surface and side surfaces are covered with an insulating film is formed on an island paper on an insulating substrate on which a semiconductor crystal layer can be epitaxially grown, and then the insulating substrate is exposed other than the first semiconductor crystal layer. A method for manufacturing a semiconductor device, comprising the step of selectively epitaxially growing a second semiconductor crystal layer thereon.