JPH03110861A - Manufacture of ferroelectric thin film - Google Patents

Abstract

PURPOSE:To form a ferroelectric capacity film on a capacity lowerpart electrode which can be processed fine and to realize a capacity part of a fine area on a semiconductor integrated circuit by a method wherein a specific thin film is formed on a tantalum Ta substrate. CONSTITUTION:For a ferroelectric capacity part on a Ta film, a Ta film 14 is applied onto SiO2 12 formed on an Si substrate 11 by an E/B vapor deposition method, a lead titanate zirconate PZT film 15 is grown by an RF sputtering method and, after that, a heat treatment is executed. An X-ray diffraction pattern is shown in the figure. It can be recognized that the PZT film 15 does not react with the Ta film 14 by the heat treatment and that a ferromagnetic thin film having no orientation in a specific direction is obtained. Thereby, a capacity part of a fine area can be realized on a semiconductor integrated circuit.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method of manufacturing a ferroelectric thin film, which enables the formation of a capacitive element with a minute area on a high-density semiconductor integrated circuit.

Conventional technology With the increasing density and integration of semiconductor integrated circuits, capacitive elements,
In particular, the miniaturization of capacitor sections that hold data in memory integrated circuits has been actively pursued. Until now, in response to the miniaturization of the area, the necessary capacitance has been achieved by thinning the Si-based dielectric capacitor film used conventionally and creating a three-dimensional structure.However, in response to the demand for further miniaturization of the area, , attempts have been made to apply ferroelectric thin films to capacitive films. Examples of ferroelectric thin films include PZT (titanic acid, lead zirconate), PLZ
T (lanthanum-added titanate, lead zirconate), etc. are used, but in order to obtain ferroelectricity, a high temperature process of 500°C or higher is required, such as film formation at high temperature or heat treatment after film formation at low temperature. Because it is necessary and the thin film is an oxide film,
A noble metal film such as Pt was used as the electrode material.

Hereinafter, a conventional capacitor section using a ferroelectric thin film as described above will be explained with reference to the drawings.

FIG. 3 is an example of a conventionally used capacitor section made of a ferroelectric thin film. In FIG. 3, 11 is a Si semiconductor substrate;
12 is a 5i02 interlayer film, 13 is a Po1y-8i wiring conductive film, 24 is a lower capacitor Pt electrode, 15 is a PZT-based ferroelectric thin film, and 16 is an upper capacitor A1 electrode.

Problems to be Solved by the Invention However, in the above configuration, since a Pt film is used for the capacitor lower electrode, microfabrication thereof is difficult and it is difficult to construct a microcapacitor portion.

Furthermore, electrode materials other than noble metals such as Pt have the problem of oxidation and reaction with the ferroelectric thin film during the high-temperature process for obtaining ferroelectrics.

Means for Solving the Problems In order to solve the above problems, the method for manufacturing a ferroelectric thin film of the present invention uses a Ta film, which does not have problems in processability or reactivity with the ferroelectric thin film, as the capacitor lower electrode. On top of that, a ferroelectric capacitor film is formed in a process in which a heat treatment is performed after low-temperature growth to reduce the effects of oxidation, thereby obtaining a microcapacitor part.

Effect: This method makes it possible to form a ferroelectric capacitor film on a capacitor lower electrode that can be microfabricated, thereby realizing a capacitor section with a minute area on a semiconductor integrated circuit.

EXAMPLE Hereinafter, an example of the present invention will be described with reference to the drawings.

FIG. 1 shows Ta of a semiconductor integrated circuit in an embodiment of the present invention.
This figure shows the structure of an on-film ferroelectric capacitor section. The ferroelectric capacitor section on the Ta film in this embodiment is constructed by replacing the PT film used for the capacitor lower electrode 24 in the conventional example in FIG.
It consists of a structure in which the a film is replaced. Figure 2 shows the E/B evaporation method using Ta
A PZT film was grown on the film by RF sputtering at a substrate temperature of 200°C for 600A, and then heated at 600°C15.
This is an X-ray diffraction pattern for a sample subjected to heat treatment for 10 minutes. The composition of PZT is P b (Z ro, 4s) in the sputtering target.

Tio, s2) 03. From FIG. 2, it was found that the above heat treatment resulted in a ferroelectric thin film in which the PZT film did not react with the Ta film and was not oriented in a particular direction.

As described above, according to this example, a PZT ferroelectric capacitor film could be formed on a Ta film with good workability by heat treatment after forming an amorphous film.

In this embodiment, the ferroelectric thin film 15 is formed by P b (Z
ro4s, Tio, s2) 03, but other Zr/Ti ratios may be used, and PLZT, PLT,
Any PZT-based ferroelectric thin film such as PTO may be used.

Further, in this embodiment, the wiring conductive film 13 is made of PolySi, but it may be a high melting point metal film such as tungsten W or molybdenum Mo.

Furthermore, although the capacitor upper electrode 16 is made of aluminum AI in this embodiment, it may be made of other electrodes or wiring materials.

Effects of the Invention As described above, the method for forming a ferroelectric thin film of the present invention provides a method for forming a PZT-based ferroelectric thin film, which was conventionally formed on a noble metal electrode film, on a Ta film with good workability. Therefore, a capacitor section with a small area can be realized on a semiconductor integrated circuit, and its practical effects are great.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of a capacitive part on a semiconductor integrated circuit according to an embodiment of the present invention, FIG. 2 is an X-ray diffraction pattern of a ferroelectric thin film on a Ta film, and FIG. FIG. 11...Semiconductor substrate, 12...Interlayer film, 13...Wiring conductive film, 14...Capacitance lower Ta electrode, 15... PZT-based ferroelectric thin film, 16...capacitor upper electrode, 24...capacitor lower Pt electrode.

Claims (4)

[Claims] (1) As a perovskite oxide ferroelectric thin film on a tantalum (Ta) substrate, the chemical formula is expressed as ABO_3, where element A is composed of lead (Pb) or lead and lanthanum (Pb, La); Element B is zircon and titanium (
A method for producing a ferroelectric thin film, the method comprising forming a thin film consisting of Zr, Ti) (0≦X≦1). (2) The method for producing a ferroelectric thin film according to claim 1, wherein a heat treatment is performed after the amorphous oxide thin film is deposited on the substrate. (3) The method of manufacturing a ferroelectric thin film according to claim 1 or 2, wherein the thin film forms a dielectric film of a capacitive element. (4) The method for manufacturing a ferroelectric thin film according to claim 3, wherein the capacitive element is a capacitive element of a semiconductor integrated circuit.