JPH11150245A - Manufacture of semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the characteristic deterioration of a capacitor element caused by heat treatment due to hydrogen gas, and to easily manufacture a semiconductor device with high reliability and productivity, when manufacturing the semiconductor device with the capacitor element where an STO (strontium titanate) film, a BST (barium titanate) film, a PZT (lead zirconium titanate) film, and a Y1 (strontium bismuth tantalum oxide) film are used as a capacity- insulating film or precious metal is used as a capacitance electrode. SOLUTION: A semiconductor device is provided with a capacitor element which consists of a lower electrode 12, a capacity-insulating film 13 with a high dielectric constant, and an upper electrode 14. When the capacitor electrode is formed, the semiconductor device is heat-treated by a gas containing hydrogen, at least once before the capacitance-insulating film 13 is formed at the lower electrode 12 of the capacitor element.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a semiconductor device, and more particularly to a method of manufacturing a semiconductor device having a capacitor element using a high dielectric constant film or a ferroelectric constant film as a capacitor insulating film and a noble metal as a capacitor lower electrode. It relates to a manufacturing method.

[0002]

2. Description of the Related Art In recent years, conductive oxides such as Ru02 and Ir02 and their metals, and noble metals such as platinum have been used as electrode materials for capacitor elements, and strontium titanate films (hereinafter referred to as STO films) or titanic acid. A dynamic random access memory (DRAM) in which a high dielectric constant material such as a barium strontium film (hereinafter, referred to as a BST film) is applied as a capacitance insulating film of a capacitor element, or a noble metal and lead zirconium titanate (hereinafter, referred to as PZ).
Significant progress has been made in the development of micro devices such as Efram (FRAM) using ferroelectric films such as a T film) or a strontium bismuth tantalum oxide (hereinafter referred to as a Y1 film). In order to manufacture this micro device, it is necessary to establish a fine processing technology for the above-mentioned noble metal and capacitive insulating film. On the other hand, it is necessary to ensure consistency with the existing semiconductor device manufacturing technology.

One of the existing technologies is a heat treatment using hydrogen gas. This aims at operating the microdevice stably. That is, in order to suppress the increased interface state density of silicon through the semiconductor device manufacturing process, a method of terminating the tangling pound of silicon with hydrogen atoms. The heat treatment, after forming a transistor, a capacitor element, aluminum wiring one after another,
This is performed at the final stage of the manufacturing process.

[0004]

In the conventional method of manufacturing a semiconductor device, a heat treatment step using hydrogen gas is performed at the final stage of the manufacturing process.
A high-permittivity material such as a film, a PZT film, and a Y1 film, a ferroelectric material, and a conductive oxide material are subjected to a reducing action of hydrogen gas. Here, since the high-permittivity material and the ferroelectric-constant material are basically oxides, various problems such as deterioration of the film quality of the capacitive insulating film due to the reduction action and increase in leak current occur.
Similarly, it is apparent that Ir02 and Ru02, which are conductive oxides, are also reduced. Further, there is also a problem that water molecules are generated at the interface between the conductive oxide and the capacitor insulating film due to the reduction action, and physical destruction of the capacitor insulating film due to the pressure of the water molecules also occurs.

The present invention has been made in view of the circumstances described above, and includes an STO film, a BST film, a PZT film, and a YO film.
When manufacturing a semiconductor device having a capacitor element using one film as a capacitor insulating film and a noble metal as a capacitor electrode, the characteristic deterioration of the capacitor element caused by heat treatment with hydrogen gas is reduced, and high reliability and productivity are also achieved. It is another object of the present invention to provide a method for manufacturing a semiconductor device which can easily manufacture a semiconductor device.

[0006]

The invention according to claim 1 is
In a method of manufacturing a semiconductor device having a capacitor element using a high-dielectric-constant film or a ferroelectric-constant film, a gas containing hydrogen is provided at least once or more before the step of forming the high-dielectric-constant film on a lower electrode of the capacitor element. A method for manufacturing a semiconductor device, characterized in that the semiconductor device is subjected to a heat treatment.

The invention according to claim 2 is that the high dielectric constant film is a film composed of at least one selected from the group consisting of a strontium titanate film, a barium strontium titanate film, and tantalum oxide. A gist is a method of manufacturing a semiconductor device according to claim 1.

[0008] The invention according to claim 3 is characterized in that the ferroelectric film is a film composed of at least one selected from the group consisting of a lead zirconium titanate film and strontium bismuth tantalum oxide. A gist of the present invention is a method of manufacturing a semiconductor device.

The invention according to claim 4 is characterized in that the lower electrode of the capacitor element is a film made of at least one selected from the group consisting of ruthenium dioxide, ruthenium, iridium dioxide, iridium and platinum. The method of manufacturing a semiconductor device according to claim 1 is summarized.

According to the present invention, the heat treatment with hydrogen gas for the purpose of stabilizing the operation of the transistor is performed in advance by S
Since the capacitor insulating film such as the TO film, the BST film, the PZT film, and the Y1 film is formed on the capacitor lower electrode, the capacitor insulating film is not subjected to the reducing action in principle. In addition, the capacitance electrode made of a conductive oxide does not change its dielectric properties and the like even when subjected to a reducing action, and thus sufficiently functions as a capacitance electrode. In addition, since water molecules generated by the reduction action are eliminated from the electrode surface, they do not directly affect the capacitance insulating film.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view showing a configuration of a semiconductor device manufactured by a manufacturing method according to an embodiment of the present invention. In the present embodiment, first, the LOCO
S (Local Oxidation of Sili)
con), etc., using a normal element isolation method.
A field oxide film 2 which is a non-active region is formed thereon, and an element active region surrounded by them is formed.

Next, a MOS transistor including a gate electrode 3, a capacitor diffusion layer 4, a bit line diffusion layer 5, and the like via a gate oxide film is formed on the element active region. This MO
The S transistor becomes a transfer transistor of the memory cell. Further, a word line 9 is formed on the field oxide film 2. This word line 9 is connected to a gate electrode (not shown) of a transfer transistor of an adjacent memory cell. Then, an interlayer insulating film 6 is formed so as to cover the gate electrode 3 and the word line 9. Here, the interlayer insulating film 6 is a silicon oxide film formed by a known chemical vapor deposition (CVD) method.

Next, a contact hole is opened on the bit line diffusion layer 5 of the MOS transistor, and a conductive material such as tungsten, titanium nitride or tungsten silicide is buried in the contact hole to form a bit line contact plug 7. . Then, after depositing a conductive film such as tungsten, the bit line 8 is formed by patterning by a known lithography and dry etching process.

Next, an interlayer insulating film 6 covering the bit line 8 is formed.
Then, a silicon oxide film is formed again by the CVD method and flattened by the chemical mechanical polishing (CMP) method. Then, an interlayer insulating film on the capacitance diffusion layer 4 is opened to form a contact hole, and the contact hole is filled with polysilicon containing a phosphorus impurity. Thus, the capacitor contact plug 20 is formed.

Next, ruthenium (Ru) having a purity of 99.9% is formed by a sputtering method using a DC magnetron discharge.
A ruthenium oxide film 10 is formed to a thickness of 400 nm using a mixed gas of oxygen and argon gas with a metal as a target. Then, an SOG (Spin on Glass) film made of organic silica serving as an etching mask
An SOG mask 11 is formed by applying a 0 nm film and patterning by a known lithography and dry etching process.

Next, the ruthenium oxide film 10 is etched under anisotropic etching conditions using a dry etching apparatus utilizing plasma discharge (ECR) by electron cyclotron resonance. Here, the gas used for etching is a mixed gas of chlorine and oxygen. In this embodiment, the chlorine gas is adjusted to about 5 to 50% and the gas flow rate is set to 240 s.
ccm. The etching rate of the ruthenium oxide film obtained at this time was about 250 nm / min. Then, the lower electrode 12 is formed by removing the unnecessary SOG mask 11 using a known etch-back method (see FIG. 2).

Next, a heat treatment using hydrogen diluted with nitrogen gas is performed. The heat treatment furnace is at normal pressure, the processing temperature is 400 ° C. or more, and the processing time is 40 minutes or more. By performing this heat treatment, the lower electrode 12 made of a ruthenium oxide film is completely reduced and turned into ruthenium metal.

Next, a capacitance insulating film 13 is formed so as to cover the surface of the lower electrode 12. Here, this capacitive insulating film 13 is formed of a 50 nm thick B deposited by a plasma CVD method.
ST film. The relative dielectric constant of this BST film is about 500. Subsequently, a 200 nm-thick ruthenium film is formed as the upper electrode 14.

In this manner, the gate electrode 3 of the transfer transistor constituting the memory cell, the capacity diffusion layer 4 to be the source / drain region, and the bit line diffusion are formed in the active region other than the field oxide film 2 on the surface of the silicon substrate 1. The lower electrode 1 which is electrically connected to the layer 5 and further to the capacitor diffusion layer 4 via the capacitor contact plug 7 and serves as an information storage electrode.
2. A bit line contact plug 7 is formed in the bit line diffusion layer 5.
, A bit line 8 electrically connected thereto is formed. Then, a stack-type capacitor is formed with the upper electrode 14 and the capacitor insulating film 13 which are opposite electrodes of the information storage electrode.

According to the present embodiment, since the heat treatment using hydrogen is performed before the formation of the capacitance insulating film, the capacitance insulating film is not reduced, and therefore, the capacitance characteristics are not deteriorated.

FIG. 4 is a diagram comparing current-voltage characteristics of a capacitor subjected to a heat treatment with hydrogen before forming a capacitive insulating film and a conventional capacitor subjected to a heat treatment after forming a capacitive insulating film according to the present embodiment. As shown in the figure, the leakage current was able to be suppressed by performing the heat treatment before forming the capacitance insulating film.

The configuration of the above embodiment is merely an example, and the material of the ferroelectric film and the like is merely selected as an example from the materials listed in the claims. Naturally, the manufacturing method of the present invention includes a semiconductor device manufacturing method in which various modifications and changes have been made from the configuration of the above embodiment.

[0023]

As described above, according to the present invention, since the heat treatment with hydrogen gas is performed before forming the capacitance insulating film, the STO film, the BST film, the PZT film, and the Y1 film are used as the capacitance insulating film. In addition, when manufacturing a semiconductor device including a capacitor element using a noble metal as a capacitor electrode, it is possible to avoid deterioration of the characteristics of the capacitor element, thereby improving the yield of the semiconductor device and increasing the productivity. is there.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a semiconductor device for describing a manufacturing method according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view of the semiconductor device for illustrating a manufacturing method according to the embodiment.

FIG. 3 is a cross-sectional view of the same semiconductor device for describing a manufacturing method according to the embodiment.

FIG. 4 is a diagram showing current-voltage characteristics of capacitors manufactured according to the embodiment and capacitors manufactured according to the related art.

[Explanation of symbols]

 Reference Signs List 1 silicon substrate 2 field oxide film 3 gate electrode 4 capacitance diffusion layer 5 bit line diffusion layer 6 interlayer insulating film 7 bit line contact plug 8 bit line 9 word line 10 ruthenium oxide film 11 SOG mask 12 lower electrode 13 capacitance insulation Film 14 upper electrode 20 capacitance contact plug

──────────────────────────────────────────────────続 き Continued on front page (51) Int.Cl. ⁶ Identification code FI H01L 29/792

Claims (4)

[Claims] 1. A method of manufacturing a semiconductor device having a capacitor element using a high dielectric constant film or a ferroelectric constant film,
A method of manufacturing a semiconductor device, comprising subjecting a semiconductor device to a heat treatment with a gas containing hydrogen at least once before forming the high dielectric constant film on a lower electrode of a capacitor element. 2. The high dielectric constant film according to claim 1, wherein the high dielectric constant film is a film composed of at least one selected from the group consisting of a strontium titanate film, a barium strontium titanate film, and tantalum oxide. The manufacturing method of the semiconductor device described in the above. 3. The semiconductor according to claim 1, wherein the ferroelectric film is a film made of at least one selected from the group consisting of a lead zirconium titanate film and strontium bismuth tantalum oxide. Device manufacturing method. 4. The capacitor according to claim 1, wherein the lower electrode of the capacitor element is a film made of at least one selected from the group consisting of ruthenium dioxide, ruthenium, iridium dioxide, iridium, and platinum. A method for manufacturing a semiconductor device.