JPH0624231B2 - Method for manufacturing semiconductor device - Google Patents

Description

The present invention relates to a method for manufacturing a semiconductor device, particularly an SOI structure.

(Prior Art) Conventionally, as a method for manufacturing an SOI structure, Oki Electric R & D
50 [1] The FIPOS method is known as shown in P63-68. FIG. 2 is a sectional view showing the FIPOS method in the order of steps.

First, as shown in FIG. 2 (a), a silicon nitride film 2 is grown on a P-type single crystal silicon substrate 1, and a photoresist 3 is formed on the silicon nitride film 2 in a region where a desired silicon island region is to be formed.
To form.

Next, as shown in FIG. 2B, the silicon nitride film 2 is removed using the photoresist 3 as a mask. Then, the P-type impurity 4 is ion-implanted into the surface portion of the silicon substrate 1 exposed thereby.

Then, the photoresist 3 is removed, the P-type impurity 4 is activated, and then proton ion implantation is performed as shown in FIG. The N-type region 5 is formed on the surface of the. At this time, the P-type impurity is ion-implanted in the surface portion of the silicon substrate 1 below the residual silicon nitride film 2 in the step of FIG. 2B, so that the N-type region is not formed.

After that, the single crystal silicon substrate 1 is subjected to N welling to a predetermined depth by a well-known anodization treatment, as shown in FIG. 2 (d).
A porous silicon layer 6 is exchanged while leaving the mold region 5.

Then, by performing an oxidation treatment, the porous silicon layer 6 is converted into a porous silicon oxide film layer 7 as shown in FIG. 2 (e). At this time, since the donors generated by the proton implantation in the step of FIG. 2 (b) disappear, the N-type region 5
Is a P-type single crystal silicon island 8. Then, a structure in which the single crystal silicon island 8 is completely separated from the underlying silicon substrate 1 by an oxide film by the porous silicon oxide film layer 7 is obtained. After this oxidation treatment, the silicon nitride film 2 remaining until the end is removed.

(Problems to be Solved by the Invention) However, in such a method, in order to completely separate the single crystal silicon island 8 from the underlying silicon substrate 1 by an oxide film, the single crystal silicon island 8 having a certain width or more is formed. There is a drawback that cannot be done, and there is a problem that is constrained by design. Further, due to the stress applied by the oxidation of the porous silicon layer 6, a defect may occur in the single crystal silicon island 8 and cause a problem such as a leak current.

(Means for Solving Problems) Therefore, in the present invention, after obtaining the final structure by the FIPOS method, a part of the porous silicon oxide film layer is removed by etching to form single crystal silicon on the oxide film layer. The island is exposed, an amorphous silicon layer is formed on the exposed single crystal silicon island and the porous silicon oxide film layer, and the amorphous silicon layer is solidified by epitaxy of the solid phase having the single crystal silicon island as a nucleus. The phase epitaxy layer.

(Operation) According to such a method, since the porous silicon oxide film layer is removed from the periphery of the single crystal silicon island, the single crystal silicon island added at the time of forming the porous silicon oxide film layer is not removed. The stress is relieved. Further, since the single crystal silicon islands are exposed on the porous silicon oxide film layer, in the solid phase epitaxy of the amorphous silicon layer, lateral solid phase epitaxy proceeds. Therefore, solid phase epitaxy over a wide area is possible, and the entire surface of the amorphous silicon layer becomes the solid phase epitaxy layer.Therefore, after this, the lateral separation of the solid phase epitaxy layer must be performed. Therefore, a new single crystal silicon island having a free width can be obtained.

(Embodiment) An embodiment of the present invention will be described below with reference to FIG.

FIG. 1 (a) shows a structure having a single crystal silicon island 13 on a P-type single crystal silicon substrate 11 which is insulated and separated by a porous silicon oxide film layer 12. This structure is obtained by the FIPOS method described with reference to FIG.

After obtaining such a structure, the porous silicon oxide film layer 12 is next etched away by hydrofluoric acid, plasma or the like to the same level as the bottom surface of the single crystal silicon island 13, so that the structure shown in FIG. As shown in b), the single crystal silicon island 13 is exposed on the porous silicon oxide film layer 12.

After that, the surfaces of the single crystal silicon island 13 and the porous silicon oxide film layer 12 are cleaned, and then the surfaces shown in FIG.
As shown in (c), an amorphous silicon layer 14 is formed. The amorphous silicon layer 14 is formed by a vapor deposition method or the like. In the case of vapor deposition, the amorphous silicon layer 14 is formed in an ultra high vacuum (10 ^-9 Tor
r), low temperature <200 ° C. The growth rate at that time is 5 to 20Å / sec. Further, the amorphous silicon layer 14 is formed in the order of several thousand angstroms to 1 μm.

Then, on the amorphous silicon layer 14 shown in FIG.
As shown in, the photoresist 15 is applied to a thickness of about 3 μm to 5 μm to eliminate surface irregularities.

After that, a part of the photoresist 15 and the amorphous silicon layer 14 is removed by using the well-known etching method, so that the amorphous silicon layer 14 is exposed flatly on the entire surface as shown in FIG. 1 (d). To do so.

Then, the amorphous silicon layer 14 is subjected to solid phase epitaxy using the single crystal silicon islands 13 as nuclei to form the amorphous silicon layer 14 as a solid phase epitaxy layer 16 as shown in FIG. 1 (e). At this time, since the single crystal silicon island 13 is exposed on the porous silicon oxide film layer 12, solid phase epitaxy of the amorphous silicon layer 14 is performed as shown by an arrow in FIG. 1 (e). It goes horizontally as well as above. Therefore, the entire surface of the amorphous silicon layer 14 easily becomes the solid phase epitaxy layer 16.

After that, by laterally separating the solid phase epitaxy layer 16 by a well-known photolithography technique, a new single crystal silicon island including the solid phase epitaxy layer 16 and the single crystal silicon island 13 having an arbitrary width is formed. To get

(Effects of the Invention) As described above, according to the manufacturing method of the present invention, the entire surface of the amorphous silicon layer formed on the single crystal silicon island and the porous silicon oxide film layer becomes the solid phase epitaxy layer. By laterally separating the solid phase epitaxy layer, a new single crystal silicon island having a free width can be obtained. Moreover, since the surface of the newly obtained single crystal silicon island is a solid phase epitaxy layer, there is an advantage that it can provide a surface with good crystallinity and reduce the leakage current of the transistor or device formed thereon.

In addition, the single crystal silicon island, which is the nucleus of solid phase epitaxy of the amorphous silicon layer, is exposed on the porous silicon oxide film layer. It can be a solid phase epitaxy layer.

Further, since the porous silicon oxide film layer was removed from the periphery of the single crystal silicon island so that the single crystal silicon island was exposed on the porous silicon oxide film layer, at the time of forming this porous silicon oxide film layer. The stress on the applied single crystal silicon island can be relaxed. Therefore, the occurrence of defects due to the subsequent heat treatment can be reduced, and the leakage current of transistors and devices can be reduced.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of a method for manufacturing a semiconductor device of the present invention in the order of manufacturing steps, and FIG. 2 is a sectional view showing the FIPOS method in the order of steps. 11 ... P-type single crystal silicon substrate, 12 ... Porous silicon oxide film layer, 13 ... Single crystal silicon island, 14 ... Amorphous silicon layer, 15 ... Photoresist, 16
...... Solid phase epitaxy layer.

Claims (1)

[Claims] 1. A step of (a) forming a single crystal silicon island by insulating and separating a porous silicon oxide film layer on a silicon substrate, and (b) etching away a part of the porous silicon oxide film layer. Exposing the single crystal silicon islands on the porous silicon oxide film layer, and (c) forming an amorphous silicon layer on the exposed single crystal silicon islands and the porous silicon oxide film layer, A step of flattening the surface of the silicon layer by an etch back method, and (d) after that, the solid phase of the amorphous silicon layer is epitaxied using the single crystal silicon island as a nucleus, and the amorphous silicon layer is solid phase epitaxy layer. A method of manufacturing a semiconductor device, comprising: