JP3071818B2 - Semiconductor substrate manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention particularly relates to SOI (Semiconductor On Insulato).
r) A method for manufacturing a semiconductor substrate having a structure.

[Prior Art] A conventional semiconductor substrate having an SOI (Semiconductor On Insulator) structure will be described with reference to FIGS. 4 (a) and 4 (b).

4 (a) and 4 (b) are cross-sectional views for explaining the configuration of a conventional semiconductor substrate.

As shown in FIG. 4 (a), a conventional semiconductor substrate Y
On the semiconductor substrate 5, for example, a silicon nitride layer (SiN layer, Si ₃ N
₄ ) or a silicon oxide layer (SiO ₂ layer) or the like, and an insulating layer 6 having high electrical insulation is formed, and a semiconductor thin film 7 is formed on the insulating layer 6; To
It is called a semiconductor substrate with SOI (Semiconductor On Insulator) structure.

When the semiconductor substrate 5 is made of silicon single crystal (Si), the insulator layer 6 and the semiconductor thin film 7 formed on the insulator layer 6 are mainly deposited in a single crystal form.

Then, using such a semiconductor substrate Y, a gate oxide film 8 is formed on the semiconductor thin film 7 as shown in FIG.
And a gate electrode 9 are formed, and a drain 10 and a source 11 are formed by ion-implanting impurities into the semiconductor thin film 7. As a result, a semiconductor device represented by a field effect transistor or the like is formed.

In recent years, such SOI (Semiconductor On Insulato)
r) In a semiconductor device typified by a field effect transistor or the like having a semiconductor substrate Y having a structure, an extremely thin semiconductor thin film 7 having a thickness of 0.1 μm or less is used as a semiconductor thin film 7 serving as a surface portion of the semiconductor substrate Y. Have been. As a result, a field effect transistor in which the performance such as driving force is drastically improved by depleting the entire active region below the gate electrode 9 is obtained.

[Problems to be solved by the invention]

However, in such a field-effect transistor having a high driving force, a large current flows in a channel region between the source 11 and the drain 10 below the gate electrode 9, that is, an active region. Excitation of many phonons causes heat to be generated, and the entire device becomes high in temperature. At high temperatures, carrier scattering by phonons increases and carrier mobility decreases,
Performance such as driving force of the field effect transistor is reduced.
In order to prevent such deterioration of transistor characteristics, it is necessary to efficiently dissipate heat generated in the element during driving.

However, in a conventional semiconductor device such as a field-effect transistor having a semiconductor substrate Y having an SOI structure, the periphery of the transistor is surrounded by an insulator having low thermal conductivity (for example, a silicon oxide layer). In addition, heat generated during driving is not satisfactorily dissipated, and the temperature of the active region below the gate electrode 9 becomes extremely high. Note that a semiconductor substrate having an SOS (Silicon-On-Sapphire) structure in which silicon is epitaxially grown on sapphire is excluded from a semiconductor substrate having an SOI structure.

In view of the above problems, an object of the present invention is to provide a method of manufacturing a semiconductor substrate capable of maintaining high performance of a semiconductor device by efficiently dissipating heat generated when the semiconductor device is driven. .

[Means for solving the problem]

The method of manufacturing a semiconductor substrate according to the present invention forms an insulator layer having a higher thermal conductivity than that of a silicon oxide layer in the semiconductor substrate by irradiating the semiconductor substrate with ions for forming an insulator. A method of manufacturing a semiconductor substrate in which a semiconductor thin film composed of a part of a semiconductor substrate remains on an insulator layer, wherein aluminum ions and nitrogen ions are used as ions for forming an insulator.

[Action]

According to the present invention, a semiconductor substrate, an insulator layer having good thermal conductivity larger than the thermal conductivity of a silicon oxide layer formed in the semiconductor substrate, and a semiconductor substrate provided on the insulator layer Is manufactured, and the heat generated in the semiconductor substrate can be efficiently dissipated from the insulating layer having good thermal conductivity toward the semiconductor substrate.

〔Example〕

 An embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a sectional view showing the structure of a semiconductor substrate according to one embodiment of the present invention.

As shown in FIG. 1, a semiconductor substrate X is a semiconductor substrate 1
And an insulating layer 2 having a higher thermal conductivity than the silicon oxide layer formed on the semiconductor substrate 1 and having good thermal conductivity, and a semiconductor thin film 3 formed on the insulating layer 2. It is provided.

The insulator forming the insulator layer 2 is aluminum nitride or a composite of aluminum nitride and silicon, and the semiconductor thin film 3 is silicon single crystal or silicon polycrystal.

When a field-effect transistor (not shown) similar to the conventional one is formed on the semiconductor thin film 3 of the semiconductor substrate X thus configured, and this field-effect transistor is driven, the active portion under the gate electrode constituting the transistor is activated. The heat generated in the region is efficiently dissipated from the insulator layer 2 toward the semiconductor substrate 1. Therefore, deterioration of transistor characteristics due to temperature rise can be prevented without increasing the temperature near the periphery of the transistor.

2 (a) to 2 (c) are sectional views for explaining a method of manufacturing a semiconductor substrate according to one embodiment of the present invention.

Semiconductor substrate 1 such as Si (silicon) shown in FIG.
Next, as shown in FIG.
Irradiation of aluminum (Al) ions and nitrogen (N) ions to form an insulating layer 2 in the semiconductor substrate 1
Is formed and the semiconductor thin film 3 composed of a part of the semiconductor substrate 1 is left on the insulator layer 2 (see FIG. 2 (c)).

The insulating layer 2 is made of a mixed crystal or amorphous made of aluminum (Al), nitrogen (N), and silicon (Si).
This insulator layer 2 is made of an insulator layer 6 in a conventional SOI structure.
It has a higher thermal conductivity than the silicon oxide layer used in (FIG. 4).

The irradiation amount of the insulator forming ions 4 is a sufficient amount that can be implanted into the semiconductor substrate 1, for example, 1 × 10 ¹⁷ [/ cm ² ] to
It is 1 × 10 ¹⁹ [/ cm ² ]. The film pressure of the semiconductor thin film 3 is
It can be controlled by the set value of the acceleration energy of the insulator forming ions 4.

The temperature condition for the semiconductor substrate 1 is room temperature, low temperature or high temperature. Further, heat treatment may be added to the semiconductor substrate 1 by using equipment such as an electric furnace.

A semiconductor device (not shown) typified by a field effect transistor or the like is formed on the semiconductor thin film 3 on the surface of the semiconductor substrate X thus formed.

3 (a) and 3 (b) are cross-sectional views for explaining a method of manufacturing a semiconductor substrate as a reference example.

FIG. 3 (b) on the solid substrate 1 'shown in FIG. 3 (a).
As shown in (1), an insulator layer 2 'is formed by depositing aluminum nitride (AlN) by a CVD method (chemical vapor deposition method) or the like.

Without this aluminum nitride, the insulator layer 2 'has good thermal conductivity and high electrical resistance.

Thereafter, a thin film (not shown) of Si (silicon) to be a semiconductor thin film is formed on the insulating layer 2 'made of aluminum nitride (AlN) by a CVD method or a sputtering method, and the same as in FIG. 2 (c). A semiconductor substrate having the structure described above is obtained. A semiconductor device (not shown) typified by a field effect transistor or the like is formed on such a semiconductor substrate.

The semiconductor substrate in this reference example is used when a semiconductor device to be formed on the semiconductor substrate does not require a single crystal thin film.

〔The invention's effect〕

According to the method of manufacturing a semiconductor substrate of the present invention, a semiconductor substrate, a thermally conductive insulator layer having a higher thermal conductivity than a silicon oxide layer formed in the semiconductor substrate, A semiconductor substrate having a semiconductor thin film in which a part of a semiconductor substrate remains on an insulator layer is manufactured, and heat generated in the semiconductor substrate is efficiently dissipated from the thermally conductive insulator layer toward the semiconductor substrate. Can be. as a result,
In a semiconductor device in which a transistor or the like is formed using this semiconductor substrate, even when the transistor is driven, the temperature around the transistor does not increase. Therefore, it is possible to prevent the transistor characteristics from deteriorating due to a temperature rise.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing the structure of a semiconductor substrate according to one embodiment of the present invention, and FIGS. 2A to 2C are cross-sectional views for explaining a method of manufacturing the semiconductor substrate according to one embodiment of the present invention. 3 (a) and 3 (b) are cross-sectional views for explaining a method of manufacturing a semiconductor substrate as a reference example, and FIGS. 4 (a) and (b) are for explaining the configuration of a conventional semiconductor substrate. FIG. 1, semiconductor base, 1 'solid base, 2, 2' insulator layer, 3 semiconductor thin film, 4 insulator formation ions

──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-52-5286 (JP, A) JP-A-63-31108 (JP, A) JP-A-1-228154 (JP, A) JP-A 61-1986 256663 (JP, A) JP-A-2-58254 (JP, A) JP-A-3-9568 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01L 27/12 H01L 21 / 265 H01L 21/316 H01L 21/318 H01L 21/762

Claims (1)

(57) [Claims] Irradiating a semiconductor substrate with ions for forming an insulator to form an insulator layer having a thermal conductivity higher than a thermal conductivity of a silicon oxide layer in the semiconductor substrate; A method of manufacturing a semiconductor substrate, in which a semiconductor thin film composed of a part of the semiconductor substrate is left on a layer, wherein aluminum ions and nitrogen ions are used as the insulator-forming ions. .