JP2001284543A - Memory device and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a ferroelectric memory device which allows a high-cost precious film such as platinum group being an electrode material of a ferroelectric capacitor to be thinned and the electrode height to be thickened to ensure the capacitance. SOLUTION: A metal film 107 made of other than platinum group is formed like a pedestal, a platinum group metal film 108 is formed so as to cover it and used as a first electrode, the first electrode is covered with a ferroelectric film 109, and then a conductive metal film 110 is formed as a second electrode, thus increasing the total thickness of the electrode films.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a memory device having a capacitor and a method of manufacturing the same.

[0002]

2. Description of the Related Art In miniaturization of a semiconductor memory, a material having a high dielectric constant is required to secure a capacitor capacity.
The area has been expanded by thinning and three-dimensional structure. In recent years, ferroelectrics composed of metal oxides have begun to be used, but due to their properties, it has been necessary to use a noble metal such as a platinum group which is hardly oxidized as an electrode. Since noble metals such as platinum group metals are difficult to process, a complex three-dimensional structure cannot be obtained, and the thickness of the first electrode is increased to increase the capacity, and the side surface of the first electrode is used.

[0003]

Since noble metals such as platinum group metals are expensive, in order to reduce production costs,
Although it is necessary to reduce the thickness, the thickness of the first electrode needs to be increased to increase the side area in order to secure the capacitor capacity.

An object of the present invention is to increase the capacitance of a capacitor by using a first electrode having a large side area without increasing the thickness of a noble metal such as a platinum group metal.

[0005]

The present invention is characterized in that the first electrode of the capacitor is made of a pedestal-shaped conductor or insulator other than a noble metal such as platinum group and a noble metal such as platinum group covering the surface thereof. The thickness of the first electrode is the sum of the thickness of the noble metal such as the platinum group and the thickness of the pedestal-shaped conductor or insulator other than the noble metal such as the platinum group. Therefore, it is possible to reduce the thickness of a noble metal such as a platinum group by increasing the thickness of the pedestal conductor or the insulator.

Examples of conductors other than noble metals such as platinum group metals include tungsten, titanium, molybdenum and the like, conductive compounds thereof such as tungsten silicide, titanium nitride, and titanium tungsten which is an alloy composed of a plurality of metals. Examples of the insulator include a silicon oxide film, a silicon nitride film, and a titanium oxide film.

[0007] These film thicknesses are such that noble metals such as platinum group metals can be made thinner in order to reduce manufacturing costs. Such a film thickness is 100 nm or more. More preferred film thickness is 150 nm to 300 n
m.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to examples.

FIG. 1 is a sectional view showing a first embodiment of the present invention.

FIG. 1A shows an element isolation region 102 on a Si substrate 101.
A source / drain region 103, a gate oxide film 104, and a MOS transistor gate electrode 105 are formed, and thereafter, an insulating film 106 is formed.

FIG. 1 (b) Next, a metal film other than the platinum group, for example, an alloy film 107 such as titanium or titanium tungsten.
Is formed, and the metal film is processed into a trapezoidal shape by photolithography and etching.

1C. Next, a platinum group metal, for example, a metal 108 such as platinum or iridium is formed into a film, and a pattern covering the metal film 107 is formed by photolithography and etching.

FIG. 1 (d) Next, a ferroelectric 108 and a metal film 109 to be a capacitor second electrode are formed, and a capacitor is formed by photolithography and etching.

The above is the first embodiment of the present invention.

FIG. 2 is a sectional view showing a second embodiment of the present invention. An insulating film 207 is formed and processed instead of the metal film 107 other than the platinum group metal of the first embodiment. The insulating film is formed of a silicon oxide film, a silicon nitride film, a titanium oxide film, or the like.

[0016]

According to the present invention, the sum of the thickness of the platinum group metal film and the thickness of the metal or insulating film other than the lower platinum group is the first electrode thickness. And the area of the capacitor can be increased.

[Brief description of the drawings]

FIG. 1 is a sectional view of a main process of a first embodiment of the present invention.

FIG. 2 is a main sectional view of a second embodiment of the present invention.

FIG. 3 shows a conventional example.

[Explanation of symbols]

 101 silicon substrate 102 device isolation region 103 source / drain region 104 gate oxide film 105 MOS transistor gate electrode 106 insulating film 107 metal film other than noble metals such as platinum group 108 capacitor first electrode made of platinum group metal 109 ferroelectric film 110 Capacitor second electrode 201 Silicon substrate 202 Element isolation region 203 Source drain region 204 Gate oxide film 205 MOS transistor gate electrode 206 Insulation film 207 Insulation film 208 Capacitor first electrode made of platinum group metal 209 Ferroelectric film 210 Capacitor second Second electrode 301 Silicon substrate 302 Device isolation region 303 Source drain region 304 Gate oxide film 305 MOS transistor gate electrode 306 Insulation film 308 Capacitor first electrode made of platinum group metal 309 Ferroelectric film 310 Capacitor second electrode

Claims (3)

[Claims] 1. A pedestal-shaped pattern formed on a substrate and made of a conductor other than a noble metal such as a platinum group, and a capacitor formed of a first electrode made of a noble metal such as a platinum group and covering the pedestal pattern. Memory device. 2. A pedestal-shaped pattern formed on a substrate and made of an insulator made of a metal other than a noble metal such as a platinum group, and a first electrode made of a noble metal such as a platinum group covering the first pattern and a ferroelectric. A memory device having a capacitor comprising a second electrode. 3. A step of forming said conductor or insulator into a pedestal pattern of a predetermined size by photolithography and etching, and forming a noble metal such as platinum group so as to cover said pattern. A method for manufacturing a memory device, comprising a step of forming a pattern by photolithography and etching.