JPS62119914A - Method for solid-phase epitaxy of semiconductor layer - Google Patents

Abstract

PURPOSE:To make it possible to form the crystal silicon layer of single crystal face easily by forming a semiconductor layer on an insulating substrate having a recess and filling the recess with the semiconductor layer, followed by heat treatment to form semiconductor grains having a single crystal face on its upper plane, and then growing the semiconductor layer by solid phase while using the semiconductor grains as seeds. CONSTITUTION:A polysilicon layer 3 is formed on an insulating substrate 1 having a recess 2. The Si layer 3 fills the recess 2. A diameter r of the recess 2 is determined in consideration of the grain size of the layer 3 and the grain size after annealing. For example, if the grain size is 500Angstrom on an average, the diameter r is determined to be about 0.6-0.8mum. Next, the grain size is enlarged by annealing (I). After forming semiconductor grains 4 having a single crystal face in the recess 2, the polysilicon layer 3 is made amorphous by ion implantation (II). The depth x in the substrate to be made amorphous is deeper than the thickness d of the layer 3 and is shallower than the sum of d and the depth h of the recess 2. A layer 5 is grown by solid phase to become a semi-crystal Si layer by using the semiconductor grains 4 as seeds.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] ' The present invention relates to SOI (silicon-on-insulator) technology for growing a single crystal silicon layer on an insulating substrate.

[Summary of the invention]

The present invention provides a solid phase growth method for a semiconductor layer in which a semiconductor layer is formed on an insulating substrate, the semiconductor layer is made amorphous using an ion implantation method, and then recrystallized by annealing. A single crystal silicon layer is grown in a solid phase on an insulating substrate by forming semiconductor grains having a single crystal plane on the upper surface within the recess.

[Conventional technology]

Generally, S is used to form semiconductor elements such as transistors on a single crystal silicon layer formed on an insulating substrate or an insulating layer.
The OL structure is attracting attention in the development of three-dimensional and highly integrated semiconductor devices.

By the way, as a solid-phase growth method of a semiconductor layer used to form the above-mentioned Sol structure, a method of solid-phase growth of a semiconductor layer by using an extension part and performing solid-phase growth from that part is known.

An example of such a solid-phase growth method for a semiconductor layer is a method using a planar pattern 21 as shown in FIG. 2, for example.

That is, first, a polycrystalline silicon layer is deposited on an insulating substrate at a predetermined thickness in the shape of a plane pattern 21 consisting of a crystallized region 22 and an extended portion 23 adjacent to and extended from the crystallized region 22. Adhesion is formed. Then, only the polycrystalline silicon layer 24 formed in the extending portion 23 is covered with a resist or the like, and the polycrystalline silicon layer in the crystallized region 22 except for the polycrystalline silicon JW 24 in the extending portion 23 is covered with silicon ions or the like. Next, the amorphous polycrystalline silicon layer in the crystallized region 22 is subjected to planar phase growth by heat treatment. At this time,
The solid phase growth is performed using the polycrystalline silicon layer 24 of the extension portion 23 as a seed, and the solid phase growth proceeds in the crystallized region 22 in the lateral direction along the main surface of the insulating substrate.

[Problem that the invention seeks to solve]

However, when solid phase growth is performed by such a method, since the polycrystalline silicon layer 24 from the extension portion 23 is used as a seed, layers having various crystal planes are formed as a recrystallized layer. That will happen.

That is, the extending portion 23 is covered during ion implantation, and the polycrystalline silicon layer 24 remains as a polycrystalline semiconductor layer. When the polycrystalline silicon layer in the crystallized region 22 is made amorphous and then recrystallized by the in-phase growth method, various crystal planes are formed in order to use the polycrystalline silicon layer 24 as a crystal seed. A recrystallized layer will be formed.

If a recrystallized layer with various crystal planes is formed in this way, even if an element is formed using such a recrystallized layer, the performance of the element will deteriorate at the boundaries of the grains. This will cause a phenomenon to occur.

SUMMARY OF THE INVENTION In view of the above-mentioned problems, it is an object of the present invention to provide a method for solid-phase growth of a semiconductor layer that can realize single crystallization of a semiconductor layer.

[Means for solving problems]

The present invention forms a semiconductor layer on the surface of an insulating substrate having a recess, fills the recess with the semiconductor layer, and then performs heat treatment to form semiconductor grains having a single crystal plane on the upper surface within the recess. However, the above-mentioned problems are solved by a method of solid phase growth of a semiconductor layer, in which the semiconductor layer is grown in a solid phase using the semiconductor grains as seeds.

Note that in the present invention, the insulating substrate includes a substrate on which an insulating layer is formed.

[Effect]

An insulating substrate with recesses is used, semiconductor grains with a single crystal plane on the upper surface are formed in the recesses of the insulating substrate, and the semiconductor layer is made into a single crystal by solid phase growth using these semiconductor grains as seeds. Plan. At this time, a single crystal plane faces the recess, and the solid phase growth from the semiconductor grain becomes solid phase growth that reflects the crystal plane of the semiconductor grain.

〔Example〕

Preferred embodiments of the present invention will be described with reference to the drawings.

In this example, semiconductor grains having a single crystal plane on the upper surface are formed in a recessed part of an insulating substrate, and the solid phase of the semiconductor layer is realized by solid phase growth using the semiconductor grains as a seed to achieve single crystallization of the semiconductor layer. It's a way of growing. Hereinafter, this embodiment/example will be explained in order of steps. Note that the lowercase alphabetic headings correspond to the division symbols in FIG.

(a) First, as shown in FIG. 1a, a polycrystalline silicon layer 3 is formed as a semiconductor layer on an insulating substrate l having a recess 2. This polycrystalline silicon layer 3 fills the recessed portion of the insulating substrate 1.

Here, the recess 2 is formed at a depth h from the surface of the insulating substrate l, and the diameter of the mouth portion 2 is r.

The diameter r of the recess 2 can be determined by considering the grain size of the deposited polycrystalline silicon layer 3 and the grain size after the annealing treatment described below. For example, if the average grain size is 500, In this case, 0.6
The size of the radius r can be set to a value of about 0.8 μm.

The polycrystalline silicon layer 3 is deposited to a thickness d by, for example, the cVD method, and is filled in the recess 2.

(b) A polycrystalline silicon layer 3 on an insulating substrate 1 having a recess 2
After forming polycrystalline silicon and filling the recess 2 with polycrystalline silicon, an annealing treatment is performed to increase the grain size, as shown in FIG. Annealing may be performed by heat treatment at about 600° C., for example. Through this annealing, the grains of the polycrystalline silicon layer 3 grow from an average size of 500 to about 1 μm.

Similarly, the grain size of the polycrystalline silicon layer 3 filled in the recess 2 is increased by annealing. That is, one semiconductor grain 4 has a grain size larger than the diameter r of the recess 2 due to grain growth by annealing, and fills the inside of the recess 2 so that the single crystal plane is on the upper surface.

(c) After forming semiconductor grains 4 having a single crystal plane on the upper surface in the recess 2, ions are implanted into the polycrystalline silicon layer 3 to transform it into an amorphous layer, as shown in FIG. 1C. to become This ion implantation uses, for example, silicon ions as a dopant, and the polycrystalline silicon 1! It is applied to the entire surface of i3. The amorphous depth X determined by the projected range Rp of this ion implantation is a value deeper than the film thickness d of the polycrystalline silicon layer 3 and shallower than the sum of the film thickness d and the depth h of the recess. This is the depth at which the crystallinity of the semiconductor grains 4 is maintained. By such ion implantation, the polycrystalline silicon layer 3
By making it amorphous, it becomes possible to grow a single crystal silicon layer.

(d) After the polycrystalline silicon layer 3 is made amorphous, as shown in FIG. Layer. In FIG. 1d, the arrow indicates the direction of solid phase growth. Solid-phase growth can be performed at a predetermined temperature for 9 hours, and is not limited to this. By appropriately selecting the conditions, a single crystal silicon layer can be grown in a region of a desired size. be able to.

Through the above steps, it is possible to implement the solid phase growth method of a semiconductor layer of this example. By using the solid-phase growth method of the semiconductor layer of this embodiment, semiconductor layers having various crystal planes are formed by growth in the conventional solid-phase growth method, but in this embodiment, a single crystal plane is formed. Since solid phase growth is performed from semiconductor grains 4 having a crystal plane on the upper surface, solid phase growth that reflects the crystal of the semiconductor particles 4 can be performed, and a single crystal silicon layer can be easily formed.

Although the semiconductor layer is a polycrystalline silicon layer in this embodiment, it is not limited thereto, and a semiconductor layer made of other materials may be used.

〔Effect of the invention〕

In the solid phase growth method of a semiconductor layer of the present invention, semiconductor grains having a single crystal plane on the upper surface within a recess are formed, and solid phase growth is performed from this semiconductor grain. Layers can be easily formed.

[Brief Description of the Drawings] Figures 1a to 1d are cross-sectional views for explaining the solid phase growth method of a semiconductor layer according to the present invention step by step, and Figure 2 is a conventional solid phase growth method of a semiconductor layer. FIG. Patent applicant Sony Corporation agent Patent attorney Koike Mima Ei Tamura - Figure 1a Figure 1C Figure 1d Figure 2

Claims (1)

[Claims] After forming a semiconductor layer on the surface of an insulating substrate having a recess and filling the recess with the semiconductor layer, heat treatment is performed to form semiconductor grains having a single crystal plane on the upper surface in the recess, and the semiconductor layer is filled with the semiconductor layer. A method for solid-phase growth of a semiconductor layer, in which the semiconductor layer is grown in a solid-phase using grains as seeds.