JP3507891B2 - Dielectric thin film and ferroelectric memory and integrated circuit - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a dielectric thin film, a ferroelectric memory and an integrated circuit. More specifically, the invention of this application relates to a new dielectric thin film that realizes a highly stable dielectric / semiconductor structure, and a new ferroelectric memory and an integrated circuit using the same.

[0002]

2. Description of the Related Art Ferroelectric memory (FRAM) is used as a memory for realizing next-generation low power consumption, high speed, and high integration.
(Registered trademark)) is known. This ferroelectric memory is a non-volatile memory that can maintain data for a long period of time without power by using a ferroelectric material in a capacitor portion that stores electric charges. Currently, platinum electrodes are mainly used in this capacitor part. This is because platinum is stable at the interface formation with the oxide, and the ferroelectric material grown on it is oriented in the <100> direction.

[0003]

However, in this ferroelectric memory, the use of platinum has the above advantages, but
Due to its catalytic action, platinum reduces the ferroelectric substance in the subsequent heat treatment in a hydrogen atmosphere and causes deterioration of memory characteristics.

In the next-generation integrated circuit, it is also considered to use a field effect transistor having a dielectric material grown on a Si substrate and its gate oxide film as a ferroelectric memory. There is a problem that reaction occurs at the interface when an oxide that is a dielectric is grown on top.

Therefore, the invention of this application has been made in view of the above circumstances, and solves the problems of the prior art, suppresses the interfacial reaction, and stabilizes the dielectric / semiconductor structure even at high temperature. It is an object of the present invention to provide a new dielectric thin film, a new ferroelectric memory and an integrated circuit capable of realizing the above.

[0006]

The invention of this application is to solve the above-mentioned problems. Firstly, a dielectric thin film formed on a semiconductor substrate is provided between the semiconductor substrate and the dielectric thin film.
Provided is a dielectric thin film having an insulating monatomic carbon film as an intervening layer .

The invention of this application is, secondly, a ferroelectric memory characterized by using the above-mentioned dielectric thin film, and thirdly, using the above-mentioned dielectric thin film. An integrated circuit characterized by being provided.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The dielectric thin film of the invention of this application is
An insulator monatomic carbon film is provided as an intervening layer when it is formed on a semiconductor substrate. More specifically, for example, as illustrated in FIG. 1, Si, GaAs
An insulating carbon film is grown from an atomic layer, for example, to several tens of nm on a semiconductor substrate such as, and a material having dielectric properties including oxide, nitride, fluoride, sulfide and the like is further stacked thereon.

[0009]

A chemically stable surface can be produced by growing one atomic layer of carbon on a semiconductor substrate.
This surface is not oxidized even in an oxygen atmosphere. By growing high dielectric material and ferroelectric material on this,
It is possible to form a steep and stable oxide / semiconductor interface by suppressing the interface reaction, which has been a problem in the past.

This can contribute to the interface stability between the gate oxide film and the semiconductor substrate in the next-generation integrated circuit, and can also be applied to the field effect type ferroelectric memory. FIG. 2 shows an example of a field effect type ferroelectric memory structure using this dielectric thin film, which is an extremely excellent device which has both low power consumption, high speed, high integration and stability.

The invention of this application has the characteristics as described above, but the embodiments will be described below in more detail with reference to the accompanying drawings.

[0013]

[Example] [Example 1] First, 2 at room temperature on a Si (100) substrate.
A 0 nm monatomic carbon film was deposited and heated at 700 ° C. in an oxygen atmosphere. Then, SrTiO ₃ which is a high dielectric material was deposited thereon at 700 ° C.

When X-ray diffraction of the produced dielectric thin film was measured, it was shown that SrTiO ₃ was oriented in the <100> direction, as is clear from FIG. In addition, in the cross-sectional structure observation with a transmission electron microscope, as shown in FIG.
It was observed that they were oriented in the 00> direction, the grain boundaries were dense, and that the carbon film / Si interface and the SrTiO ₃ / carbon film interface were always steep and had no reaction layer. In the case where the grown directly SrTiO ₃ at a high temperature on the Si, typically, a reaction occurs at the interface, as also illustrated in FIG. 5, the amorphous SrTiO ₃ and SiO ₂ layer (light swath) (slightly above it Although a bright strip portion is formed, the invention of this application suppresses the interfacial reaction and realizes a stable dielectric / semiconductor structure.

Of course, even if a ferroelectric material such as Pb (Zr _x , Ti _1-x ) O ₃ or Bi ₄ Ti ₃ O ₁₂ is used instead of the high-dielectric material, it is possible to obtain the same excellent characteristics. A dielectric thin film can be realized.

It is needless to say that the invention of this application is not limited to the above examples, and various details can be made.

[0017]

As described in detail above, the invention of this application provides a new dielectric thin film capable of suppressing an interfacial reaction and realizing a stable dielectric / semiconductor structure even at a high temperature. By using a thin film, a next-generation ferroelectric memory and a next-generation integrated circuit having low power consumption, high speed, high integration, and stability will be realized.

[Brief description of drawings]

FIG. 1 is a diagram for explaining a dielectric thin film of the invention of this application.

FIG. 2 is a conceptual diagram showing an example of a FET type ferroelectric memory structure using the dielectric thin film of the invention of this application.

FIG. 3 is a diagram showing an X-ray diffraction measurement result of a dielectric thin film having a SrTiO ₃ / carbon film / Si (100) structure.

FIG. 4 is a transmission electron microscope image of a dielectric thin film having a SrTiO ₃ / carbon film / Si (100) structure.

FIG. 5 is a transmission electron microscope image of a conventional dielectric thin film having a SrTiO ₃ / Si (100) structure.

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Claims (3)

(57) [Claims] 1. A dielectric thin film formed on a semiconductor substrate, wherein an insulating monatomic carbon film is provided as an intervening layer between the dielectric thin film and the semiconductor substrate. 2. A ferroelectric memory, wherein the dielectric thin film according to claim 1 is used. 3. An integrated circuit using the dielectric thin film according to claim 1.