JPH05217931A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To reduce a tunnel leakage current flowing in an insulating film when a high electric field is applied concerning a method of treating the insulating film. CONSTITUTION:First, fluorine ions with the number of 1X10<13>cm<-2> or more are implanted in a silicon oxide film 12 formed on a semiconductor substrate 11 and a heat treatment is performed at the temperature of 900 deg.C or below. Second, oxygen ions with the number of 1X10<12>cm<-2> or more are implanted in the silicon oxide film 12 formed on the semiconductor substrate 11 and the heat treatment is performed at the temperature of 800 deg.C or below. Third, the fluorine ions with the number of 1X10<13>cm<-2> or more are implanted to the surface of the semiconductor substrate 11 and a silicon oxide film 14 by a heat oxidation is formed on the surface of the substrate 11 and the heat treatment for the substrate 11 is performed at the temperature of 900 deg.C or below. Finally the oxygen ions with the number of 1X10<12>cm<-2> or more are implanted to the surface of the semiconductor substrate 11 and the silicon oxide film 14 by the heat oxidation is formed on the surface of the substrate 11 and the heat treatment for the substrate 11 is performed at the temperature of 800 deg.C or below.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device manufacturing method, and more particularly to an insulating film processing method. In recent years, with the miniaturization of memory devices, high electric fields have been applied to the insulating films of capacitors and gates. At this time, the tunnel leak current flowing in the insulating film has an adverse effect such as a decrease in device life and a decrease in charge retention time. Therefore, an insulating film with a small tunnel leak current is required.

[0002]

2. Description of the Related Art In a conventional semiconductor device manufacturing method element, an oxide film, a nitride film, or a multilayer film thereof is used as an insulating film. However, when the device is miniaturized, the electric field applied to the insulating film increases and the tunnel leakage current flowing in the insulating film increases.

[0003]

The insulating film formed on the device according to the conventional example has a problem that the tunnel leakage current flowing through the insulating film increases with the miniaturization and the reliability of the device decreases.

An object of the present invention is to reduce tunnel leak current flowing in an insulating film when a high electric field is applied.

[0005]

[Means for Solving the Problems] 1) The silicon oxide film (12) formed on the semiconductor substrate (11) is solved.
Fluorine ion (F ⁺ ) is implanted into the substrate at a dose of 1 × 10 ¹³ cm ^-2 or more, and the semiconductor substrate is heat-treated at a temperature of 900 ° C. or less, or 2) a semiconductor device is manufactured on the semiconductor substrate (11). Silicon oxide film formed (12)
Oxygen ion (0 ⁺ ) is implanted into the substrate at a dose of 1 × 10 ¹² cm ^-2 or more, and the semiconductor substrate is heat-treated at a temperature of 800 ° C or lower, or 3) a semiconductor substrate (11) has a surface. Fluorine ion (F ⁺ ) is implanted at a dose of 1 × 10 ¹³ cm ^-2 or more, and then a silicon oxide film (14) is formed on the surface of the semiconductor substrate by thermal oxidation. 4) A method for manufacturing a semiconductor device in which heat treatment is performed at 4 or 4) Oxygen ions (0 ⁺ ) are implanted into the semiconductor substrate (11) from the surface by a dose of 1 × 10 ¹² cm ^-2 or more, and then the semiconductor substrate surface is thermally oxidized. This is achieved by a method of manufacturing a semiconductor device in which a silicon oxide film (14) is formed and then the semiconductor substrate is heat-treated at a temperature of 800 ° C. or lower.

[0006]

(Function) FIGS. 1 (A) to 1 (C) are explanatory views (1) of the principle of the present invention. 2 (A) to 2 (C) are explanatory views (2) of the principle of the present invention.

In the figure, 11 is a silicon (Si) wafer, 12
Is a silicon dioxide (SiO ₂ ) film, 13 is an implanted ion, and 14 is an SiO ₂ film in which the implanted element is incorporated. FIG. 1 shows a case where an oxide film is formed on a Si wafer and then ion implantation is performed. FIG. 2 shows a case where the oxide film is formed after ion implantation on the Si wafer.

In any of the oxide films, the incorporated elements suppress the tunnel leak current, as will be seen from FIGS. The reason why the incorporated element suppresses the tunnel leak current is considered as follows.

The implanted element (F, O) is +1 at the time of implantation.
It is injected into SiO ₂ at a valency, but it becomes negatively charged when incorporated into the SiO ₂ network. This is due to the high electronegativity of these elements. When a region of negative charge is formed in the middle of the SiO ₂ film, Si tilted so that it goes down from Al toward Si.
Since the conduction band edge of O ₂ is bent upward, the barrier thickness due to the SiO ₂ film between Al / Si at the Fermi level of Al becomes thicker than that of the SiO ₂ film not implanted with these elements. The number of tunnel electrons passing through the SiO ₂ film is reduced and the leak current is suppressed.

[0010]

EXAMPLE An example corresponding to FIG. 1 will be described. First, p-type silicon (pS
i) A SiO ₂ film 12 was formed on the wafer 11, and fluorine ions (F ⁺ ) or oxygen ions (O ⁺ ) were implanted into the SiO ₂ film 12.

An example of injection conditions is as follows. Incident angle 7 °, energy 4 KeV, dose amount 1 × 10 ¹² , 1 × 10 ¹³
cm ^-2 . The post-implantation annealing was performed at 700, 800, and 900 ℃ for 10 minutes to fabricate Al gate MOS.

Next, an embodiment corresponding to FIG. 2 will be described.
F ⁺ energy of 10 KeV or less and a dose of 1 × 10 ¹³ cm ^-2 or more are implanted on the surface of a semiconductor substrate, and then a SiO ₂ film is formed on the surface of the semiconductor substrate by thermal oxidation (850 to 900 ° C). The substrate is heat-treated at a temperature of 900 ° C or lower.

Alternatively, 0 ⁺ is injected into the surface of the semiconductor substrate at an energy of 10 KeV or less and a dose amount of 1 × 10 ¹² cm ^-2 or more,
Next, a silicon oxide film is formed on the surface of the semiconductor substrate by thermal oxidation (850 to 900 ° C), and then the semiconductor substrate is heated to 800 ° C.
Heat treatment is performed at the following temperature.

FIG. 3 shows a sample in which 1 × 10 ¹² cm ⁻² of F ⁺ was injected.
It is the figure which showed the Fowler-Nordheim plot. The figure is 1
J / E ² (A / V ² ) with respect to / E (cm / V) is shown.

Here, J is the current density (A / cm ² ) and E is the electric field (V / cm). In this case, it can be seen that the tunnel leakage current is decreased when F ⁺ is injected, in both cases without annealing and for each annealing temperature, as compared with the case where no dose is injected.

FIG. 4 shows a sample in which F ⁺ is injected at 1 × 10 ¹³ cm ^-2.
It is the figure which showed the Fowler-Nordheim plot. In this case as well, it can be seen that the tunnel leakage current decreases when F ⁺ is injected, in both cases of no annealing and for each annealing temperature, as compared with the case where no dose is injected. The effect of reducing the leakage current is greater than when the dose is 1 × 10 ¹² cm ^-2 .

FIG. 5 shows a sample injected with 1 × 10 ¹² cm ^-2 of O ⁺ .
It is the figure which showed the Fowler-Nordheim plot. In this case, 1 × 10 ¹² cm ^-2 compared to no dose without injection
Does not have the effect of reducing the tunnel leak current.

FIG. 6 shows a sample in which 1 × 10 ¹³ cm ^-2 of O ⁺ was injected.
It is the figure which showed the Fowler-Nordheim plot. In this case, the tunnel leakage current is lower in the 800 ° C anneal and higher than the no dose in the 900 ° C anneal, as compared to the no-dose implantation.

FIG. 7 shows a sample in which 1 × 10 ¹² cm ⁻² of F ⁺ was injected.
It is a profile of F concentration in the depth direction. Figure 8 shows F ⁺
This is a profile of F concentration in the depth direction of the injected sample at 1 × 10 ¹³ cm ^-2 .

In any of the dose amounts, if annealing is performed at 1000 ° C. or higher, fluorine almost diffuses outward, and the effect of fluorine cannot be expected. Therefore, it is necessary to anneal at 900 ° C. or lower.

FIG. 9 is a diagram showing the flat band voltage V _fb with respect to the annealing temperature of a sample in which 1 × 10 ¹³ cm ⁻² of each element is implanted. The effect of each element is less than that of no dose, and the V _fb shift amount with respect to the annealing temperature is within 0.2 V.

[0022]

According to the present invention, the tunnel leak current flowing through the insulating film can be reduced when a high electric field is applied due to miniaturization. As a result, the reliability of the dielectric film and gate insulating film of the capacitor was improved, which contributed to the miniaturization of semiconductor devices.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of the principle of the present invention (1)

FIG. 2 is an explanatory view of the principle of the present invention (2)

[Fig. 3] Fowler- of a sample in which 1 × 10 ¹² cm ^{-2 of} F ⁺ was injected
Diagram showing the Nordheim plot

[Fig. 4] Fowler- of a sample in which 1 × 10 ¹³ cm ^{-2 of} F ⁺ was injected
Diagram showing the Nordheim plot

FIG. 5: Fowler-of a sample in which O ⁺ is injected at 1 × 10 ¹² cm ^-2
Diagram showing the Nordheim plot

FIG. 6 Fowler-of a sample into which 1 × 10 ¹³ cm ^{-2 of} O ⁺ was injected
Diagram showing the Nordheim plot

FIG. 7 Depth profile of F concentration of the sample in which F ⁺ is injected at 1 × 10 ¹² cm ^-2

FIG. 8: Profile of F concentration in the depth direction of the sample in which 1 × 10 ¹³ cm ^{-2 of} F ⁺ was injected

FIG. 9 is a diagram showing a flat band voltage V _fb with respect to an annealing temperature of a sample in which 1 × 10 ¹³ cm ^{−2 of} each element is implanted.

[Explanation of symbols]

 11 Si wafer on semiconductor substrate 12 Silicon oxide film 13 Implanted ions 14 Silicon oxide film with implanted elements

Claims (4)

[Claims] 1. A dose of 1 × 10 ¹³ cm of fluorine ions (F ⁺ ) is added to a silicon oxide film (12) formed on a semiconductor substrate (11).
^A method for manufacturing a semiconductor device, which comprises injecting ^-2 or more and heat-treating the semiconductor substrate at a temperature of 900 ° C. or lower. 2. A dose amount of oxygen ions (0 ⁺ ) of 1 × 10 ¹² cm ^-2 to a silicon oxide film (12) formed on a semiconductor substrate (11).
A method for manufacturing a semiconductor device, comprising the steps of implanting the above and subjecting the semiconductor substrate to a heat treatment at a temperature of 800 ° C. or lower. 3. Fluorine ions from the surface of the semiconductor substrate (11)
(F ⁺ ) is implanted at a dose of 1 × 10 ¹³ cm ^-2 or more, then a silicon oxide film (14) is formed on the surface of the semiconductor substrate by thermal oxidation, and then the semiconductor substrate is heat treated at a temperature of 900 ° C or less. A method for manufacturing a semiconductor device, comprising: 4. A semiconductor substrate (11) is provided with oxygen ions (0
⁺ ) Is implanted at a dose of 1 × 10 ¹² cm ^-2 or more, then a silicon oxide film (14) is formed on the surface of the semiconductor substrate by thermal oxidation, and then the semiconductor substrate is heat-treated at a temperature of 800 ° C or less. A method for manufacturing a semiconductor device, comprising: