JPH07120702B2 - Method for manufacturing semiconductor device - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a semiconductor device by ion implantation, and particularly, an SOI (Silicon on Insulator) in which a silicon layer and an insulating layer having a correct composition ratio are in contact with each other at a sharp interface. )
The present invention relates to a method for manufacturing a semiconductor device including a substrate.

Conventional technology For example, SIMOX technology (Separation bu I
The case of Mplanted OX-ygev) will be described with reference to FIG. As shown in FIG. 3 (a), the silicon single crystal 2 (10
0) ¹⁶ O ⁺ 21 on the surface 20a at an acceleration energy of 80 KeV and 1 × 1
After injecting ¹⁸ ious / cm ² and annealing at 1150 ° C. in a nitrogen atmosphere to form the insulating layer 21, 1 as shown in FIG.
An epitaxial layer 22 of about μm is stacked, and a third layer is formed on this layer 22.
A predetermined semiconductor element 23 is formed as shown in FIG. twenty four
Is a peripheral insulator region, 25 is a gate electrode, 26 and 27 are sources,
The drain electrode 28 is a gate insulating film.

Except for the surface epitaxial layer, the SOI structure substrate formed by such a method, as shown in FIG. 3 (d), has a silicon single crystal layer 20 made of a part of the substrate, irradiation damage and oxygen from the surface side. Layer 29 containing a large amount of impurities, Si with the correct composition ratio
It becomes the O ₂ layer 21.

Problems to be Solved by the Invention In the conventional method, a damage layer 29 is widely left between the surface silicon layer 20 and the SiO ₂ layer 21 as shown in FIG. This layer 29 reduces the steepness of the Si-SiO ₂ interface, also in the case of forming a semiconductor element on a surface silicon layer a path for leakage current. Therefore, in the current device, an epitaxial layer 22 is stacked on the surface silicon layer and an element is formed on this layer 22 as shown in FIG. Impurity diffusion layer for example 26 and 27 in this case semiconductor element has not reached the Si-SiO ₂ interface, it is not alive, characterized in that the parasitic capacitance of the SOI structure is small, and since the gain epitaxial layer 22, also becomes expensive.

Means for Solving the Problems The present invention is to form a radiation damage layer by implanting silicon ions or rare gas ions deeper than the range of ions used in manufacturing an SOI substrate, and forming an insulator layer on the same substrate by ion implantation. It is a method of obtaining a structure in which a semiconductor element is formed on a part of the silicon substrate on the insulating layer.

Action Point defects caused by ion implantation are annealed to SO
Although it remains as a secondary defect on both sides of the I structure insulator layer, the damage between the surface silicon layer and the insulator layer is reduced by trapping the secondary defect at the time of SOI production in the damage layer by another ion implantation, Get a steep interface.

Example An example of the present invention in which silicon ions and oxygen ions are implanted into the surface of a silicon substrate (100) will be described below with reference to FIG. As shown in FIG. 1 (a), the silicon ion 2 is accelerated on the (100) surface 1a of the silicon substrate 1 with an acceleration energy of 200.
An irradiation damage layer 3 is formed in advance by injecting about 1 × 10 ¹⁶ cm ^{-2 with} KeV. Part of the substrate 1 on the layer 3 is a surface silicon single crystal layer
It becomes 1A. Next, as shown in FIG. 1 (b), a range is set to be shallower than the irradiation damage layer 3 generated by this, and oxygen ions 4 are implanted at an acceleration energy of 100 to 120 KeV to about 1 × 10 ¹⁸ cm ^-2 and an insulator is formed. Form layer 5. After that, annealing is performed at 1000 to 1200 ° C. for about 1 to 10 hours in a nitrogen or argon atmosphere, and defects caused by oxygen ion implantation are captured in the damaged layer 3 of silicon oil. The SOI substrate manufactured by this method has a surface silicon layer 1A and an insulator layer 5 as shown in FIG. 1 (b).
There are few defects 6 including damage at the interface with and, and all surfaces are steep.

Even if the silicon substrate surface is the (111) surface, similar results can be obtained by using rare gas ions instead of silicon as an ion beam and oxygen molecule, nitrogen, or nitrogen molecule ions instead of oxygen. Needless to say. In this way
After the SOI structure is manufactured, a semiconductor element 23 such as a predetermined MOS transistor is formed on the crystalline silicon layer 1A on the surface to form an integrated circuit structure having an SOI structure. Reference numeral 24 is an insulating film such as SiO ₂ formed around the element 23.

Another embodiment of the present invention in which nitrogen ions and oxygen ions are implanted into the surface of the silicon substrate (100) will be described below with reference to FIG. First, as shown in FIG. 2 (a), the silicon substrate 1
Nitrogen ions 11 are implanted at a dose of 2 × 10 ¹⁷ to 2 × 10 ¹⁸ cm ^{-2 on} (100) surface 1A of about 200 KeV to form a nitride layer 12, which is annealed at 1000-1200 ° C. in a nitrogen or argon atmosphere. To do. Then, as shown in FIG.
A dose of 1 to 3 × 10 ¹⁸ cm ^{2 is} implanted at 0 to 180 KeV and annealed at 1000 to 1200 ° C. in a nitrogen or argon atmosphere to form an oxide layer 13.

By first producing the Si ₃ N ₄ layer 12 by the above process, this layer 12 induces a large stress in the silicon single crystal layer. The stress layer 12 is made to capture defects associated with oxygen ion implantation and further unwanted implantation impurities. The SOI substrate manufactured by this method has few defects at the interface between the surface silicon layer and the oxide film layer 13, and the interface becomes sharp.

It is needless to say that the same result can be obtained even when the silicon substrate surface is the (111) plane and oxygen molecular ions are used instead of oxygen ions and nitrogen molecular ions are used instead of nitrogen ions as the ion beam. After the SOI structure is manufactured in this manner, a predetermined semiconductor element 23 is formed on the crystalline silicon layer shown in FIG. 1 (c).

EFFECTS OF THE INVENTION As described above, according to the present invention, irradiation damage due to ion implantation for forming an insulating layer, and unnecessary implanted impurities are prevented, and damage layer due to other ion implantation or stress layer due to compound film is eliminated. By using the traps, the interface between the surface silicon layer and the insulating layer becomes steep and has a low defect. Therefore, when a semiconductor element is built in the surface silicon layer, the depth of the impurity diffusion layer can be lowered to the interface.
The original configuration can be adopted, which contributes to the production of high-performance SOI semiconductor devices.

[Brief description of drawings]

FIG. 1 is a process cross-sectional view showing a method for producing an insulator layer inside a substrate by implanting silicon ions into a silicon (100) substrate surface and then implanting oxygen ions in one embodiment of the present invention, FIG. 2 shows a silicon (10) according to another embodiment of the present invention.
0) Process cross-sectional views showing a method of implanting nitrogen ions into the substrate surface to form a nitride layer, and then implanting oxygen ions to form an oxide layer, and FIG. 3 is a process for explaining a conventional example. FIG. 1 ... Silicon substrate, 1A ... Surface silicon single crystal layer, 2
...... Silicon ion beam, 4 ... Oxygen ion beam,
3 ... Irradiation damage layer, 5, 13 ... Insulator layer, 11 ... Nitrogen ion beam, 12 ... Nitride layer.

Claims (2)

[Claims] 1. A method of manufacturing a semiconductor device, comprising: implanting ions into a silicon single crystal substrate a plurality of times to form an insulator layer in the substrate; and forming a semiconductor element in the silicon layer on the insulator layer. A first step of implanting silicon ions or rare gas ions, and an ion or oxygen atom containing oxygen atoms shallower than the range of the ions implanted in the first step after the first step. Second ion implantation
A method of manufacturing a semiconductor device, comprising: 2. A method of manufacturing a semiconductor device, comprising ion-implanting a silicon single crystal substrate a plurality of times to form an insulator layer in the substrate, and forming a semiconductor element in the silicon layer on the insulator layer. A first step of implanting an ion containing an oxygen atom or an ion containing a nitrogen atom, and a silicon ion or a rare gas deeper than the range of the ion implanted in the first step after the first step. Second ion implantation
A method of manufacturing a semiconductor device, comprising: