JPS6135548A - Manufacturing method of semiconductor device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] C. Field of Application of the Invention] The present invention relates to a method for manufacturing a capacitor for a large-scale integrated circuit (LSI), and in particular a method for manufacturing a capacitor that has a good 88 withstand voltage even when the dielectric film is thin. Regarding.

[Background of the invention]

Japanese Patent Laid-Open No. 53-43485 describes the formation of a capacitor in parallel with the load resistance of a flip-prop type memory cell in order to achieve high-speed operation in LSI, especially bipolar memory, and to prevent the occurrence of soft errors due to alpha rays. As stated, it is a well-known fact.

The bipolar memory capacitor currently uses the junction capacitance of a Schottky barrier diode. However, the maximum capacitance density of the Schottky barrier diode is 3.4
fF/μm2, and the above memory cell is high speed and α
In order to operate without generating soft errors due to lines,
Each of the above capacitors requires a capacitance of about 0.5 PF.

Therefore, when only a Schottky diode is used, the area of one capacitor is about 150 μm2, which occupies most of the area of the memory cell and becomes a major obstacle to high integration.

However, when introducing a capacitor, it is desirable that the capacitance density be at least 7.0 f F/μm 2 or more in order to reduce the size of the memory cell due to problems in designing the memory cell.

A thermal oxide film can be considered as one of the above capacitor materials, but since the relative dielectric constant of a thermal oxide film is as small as 3.8, 7.
In order to obtain a capacitance density of about 0 fF/μm, the collagen of the thermal oxide film must be about 50, and with the current thermal oxidation technology, the LS
It has been difficult to obtain an absolute R film with a sufficiently low defect density as an I capacitor material.

Therefore, one way to obtain a capacitor with a sufficiently low defect density and a desired capacitance is to
in, on top, Ta, O,, Tie, with a large dielectric constant,
It is possible to reduce the decrease in capacitance and pinholes by performing feWJ on a film made of a high dielectric constant material such as Nb, Os, HfO, etc.

However, the above-mentioned high dielectric constant insulating film is often formed by a sputtering method or a reactive sputtering method.

This may cause plasma damage to the underlying Sin, etc., or there may be a large mismatch at the interface between the Sin and the high dielectric constant T13 green film, or a deviation from the chemical composition ratio of the high dielectric constant material film may occur. Due to these presumed causes, the withstand voltage of the capacitor dropped, and sufficient reliability as a dielectric material for LSI capacitors could not be obtained.

Also, “Symp, VLSI Thec by Kato et al.
hnol, Dig.

Paper, (1983), pp. 86-87'' and JP-A No. 59-4142-8, the oxidation of Ta, Os/Si in water vapor causes the oxidation of TaO and Si at the interface. With the method of forming Si, a capacitor with a higher withstand voltage than a single SiO2 film can be formed, but the SiO□ generated at this interface lowers the capacitance density, and the characteristics of the high dielectric constant material of Ta, 0.' The disadvantage was that the information was lost.

[Purpose of the invention]

SUMMARY OF THE INVENTION In view of the above-mentioned drawbacks of the prior art, an object of the present invention is to provide a semiconductor manufacturing method that can reduce the defect density of a capacitor dielectric without reducing capacitance.

(Summary of the Invention) The concept of the present invention is to create a high dielectric constant insulation IIA by heating the film in a dry oxidizing atmosphere. The object of the present invention is to suppress the increase in the thickness of the Si at the interface between Si and Si, improve the damage of the Si, and the properties of Ta, O, and form a dielectric for a capacitor with a low defect density.

[Embodiments of the invention]

Hereinafter, the concept of the present invention will be explained using examples.

FIG. 1 illustrates the manufacturing process of a capacitor formed using the 41st idea of the present invention using cross-sectional views.

As shown in FIG. 1(a), after forming the F41 insulating film 2 for the element amount around the region on the Si substrate 1 where the capacitor is formed, as shown in FIG. Si substrate 1
The surface of the Ta205 film 4 is oxidized at 950°C using oxygen gas diluted with nitrogen gas to form about 20 SiO. Deposited onto 5iO23 using a process-responsive sputtering method. In this reactive sputtering method, a Ta gold scrap target is sputtered in a plasma of argon gas containing oxygen gas. After this, in a dry oxygen atmosphere,
For example, when annealing at 800°C for about 30 minutes, Ta-2
The damage to SiO□3 that occurred during the sputtering of 0 is recovered, and the Taz○ film 4 also becomes a dense structure, the dielectric constant increases, and the defects in the Ta and O films are also recovered. It is expected to be. Next, as shown in FIG. 1(d), a capacitor is formed between the substrate 1 and the A and Q electrodes 5 by patterning an AQ thin film as the upper electrode of the capacitor.

FIG. 3 shows the relationship between the defect density of a capacitor formed by the method of the present invention and the above oxygen annealing temperature. As can be seen from FIG. 3, when the annealing temperature exceeds 600° C., the defect density decreases significantly. Note that the defect here means
The capacitor has an area of 1 mm" and the voltage when the leakage current between the -An electrode 5 and the Si substrate 1 is 10-"A is 1/2 or less of the average voltage. .

FIG. 4 shows the relationship between the heating temperature and capacitance density of the capacitor. The capacitance density hardly changes until the heating temperature reaches 400℃, but it decreases slightly at 600℃ and increases to 70℃.
It increases at temperatures above 0°C and decreases at 1000°C. Furthermore, the leakage current remains unchanged up to 800°C and decreases at 1000°C.

Therefore, by the dry oxygen annealing method of the present invention.

Ta, O, / S LO, / Si with extremely low defect density without decreasing capacity or increasing leakage current
type capacitor can be formed.

In the embodiments of the present invention, tantalum oxide was used as the high dielectric constant insulating film, but niobium oxide, titanium oxide, vanadium oxide, zirconium oxide, hafnium oxide, aluminum oxide, or a mixture thereof may be used instead of tantalum oxide. A similar effect can be expected when used in In addition, although dry oxygen was used in this example as the heat treatment atmosphere, it goes without saying that the concept of the present invention can also be applied to other oxygen gas diluted with Ar, N, etc., No2, etc. Nor.

〔Effect of the invention〕

According to the present invention, the defect density can be reduced without reducing the withstand voltage and capacity of the capacitor using the Ta205/sio,/si structure. /
Even if the film thickness of SiO becomes thinner, 1. Sufficient reliability can be obtained as a capacitor material for SI.

[Brief explanation of the drawing]

Figure 1 is a diagram showing the capacitor manufacturing process according to the method of the present invention, Figure 2 is a curve diagram showing the relationship between oxygen annealing temperature and defect density, and Figure 3 is a curve diagram showing the relationship between oxygen annealing temperature and capacitance density. It is a diagram. 1... Si substrate, 2... Inter-element isolation insulating film, 3...
・Atsushi 1 Figure (missing) Cb) (d) Straw 2 Figure 3

Claims (1)

[Claims] 1. A semiconductor device in which SiO_2 and a high dielectric constant insulating film are laminated on a Si substrate, and a high dielectric constant insulating film/SiO_2/Si is formed is heated in a dry oxidizing atmosphere. A method for manufacturing a semiconductor device, characterized in that: 2. The high dielectric constant insulating film according to claim 1 contains at least one constituent selected from the group of tantalum oxide, niobium oxide, titanium oxide, vanadium oxide, zirconium oxide, hafnium oxide, and aluminum oxide. A method for manufacturing a semiconductor device, characterized in that: