JPH05259124A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To provide the manufacturing method, of a semiconductor device, wherein a substrate is hardly irradiated with electrons and is irradiated with negative ions when the semiconductor device is manufactured while the side of the substrate is used as an anode, a counter electrode is used as a cathode and a high-frequency plasma is generated between both electrodes. CONSTITUTION:A gas which contains at least one out of fluorine, oxygen, chlorine, bromine, nitrogen and hydrogen is set to a plasma state; negative ions are used after they have been taken out through a net-shaped anode 2. That is to say, since the mobility of electrons generated in a plasma state is extremely large, the electrons can be captured and gathered efficiently by using the net-shaped anode 2, and it is sufficient that a substrate 4 is not irradiated with inessential electrons. Thereby, since ions with which the substrate 4 is irradiated are not positive ions but negative ions and the substrate is not irradiated with electrons, a chemical reaction near the surface of the substrate progresses extremely smoothly. As a result, an extremely excellent semiconductor device can be manufactured.

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 using plasma in various manufacturing processes of the semiconductor device such as etching of a resist, CVD growth of an oxide film or modification of a formed oxide film. is there.

[0002]

2. Description of the Related Art Generally, plasma is composed of ions which are positively charged particles, electrons which are negatively charged particles, and neutral atoms.
These positive and negative charged particles balance each other in the plasma, and the plasma as a whole is electrically neutral.

Therefore, in the generation of plasma in the manufacture of a semiconductor device, it is general that the substrate side attracting positive ions is used as a cathode and the counter electrode is used as an anode, and the plasma gas is excited at a high frequency between the two electrodes.

However, when an element having a large electronegativity, such as fluorine, oxygen, chlorine, bromine, or nitrogen, is irradiated as a positive ion on the substrate, an electron is emitted from an element on the substrate having an electronegativity smaller than that element. It robs and becomes a neutral atom or negative ion.

At this time, an electron-deprived element such as H ⁺ (a large amount of hydrogen is contained in an organic CVD material), Na ^+, or K ⁺ having a large diffusion mobility is exposed to negative radiation. Due to the recoil of ions, there is a drawback that the performance of the semiconductor device is significantly deteriorated by being gradually driven to the deep portion of the substrate such as the vicinity of the gate. In particular, Na ⁺ makes this deterioration tendency remarkable.

Originally, for example, when aluminum is plasma-etched with chlorine, the reaction between positively polarized aluminum and negatively polarized chlorine is a preferable state. Further, when the resist is plasma-etched with oxygen, a reaction between positively polarized carbon or hydrogen constituting the resist and negatively polarized oxygen is a preferable state.

Similarly, when active oxygen is used for forming and modifying a SiO ₂ film, the action of positively polarized silicon and negatively polarized oxygen is in a preferable state. As in the above-mentioned examples, the element must act like a negative ion in the chemical reaction near the surface of the substrate.

Elements such as fluorine, oxygen, chlorine, bromine, and nitrogen have a large electronegativity and tend to be negative ions originally, but since they are forcibly positive ions due to high-frequency energy, the plasma temperature Unless the temperature is sufficiently high, electrons that are negatively charged particles are likely to be taken in and become negative ions. This is remarkable when coexisting with an element that is more easily cationized.

As shown in the above examples, it is more rational to use negative ions due to the nature of the chemical reaction, and the above-mentioned drawbacks that occur when positive ions are used are avoided. Therefore, in order to attract the negative ions to the substrate, there is a method of using the substrate side as an anode and the counter electrode as a cathode.

However, in this case, there is a drawback in that the electrons, which are likely to move, are irradiated onto the substrate, and the effect of negative ions does not increase relative to the amount of discharge on the substrate.

[0011]

SUMMARY OF THE INVENTION According to the present invention, when a semiconductor device is manufactured by using a substrate side as an anode and a counter electrode as a cathode to generate high-frequency plasma between both electrodes, it is difficult for electrons to irradiate the substrate and negative ions are generated. It is intended to provide a method for manufacturing an irradiated semiconductor device.

[0012]

According to the present invention, a substrate side is used as an anode, a counter electrode is used as a cathode, and a gas containing at least one element selected from fluorine, oxygen, chlorine, bromine, nitrogen and hydrogen is used between both electrodes. Negative ions of the element that are brought into a plasma state and taken out through a mesh-like anode are used for manufacturing a semiconductor device. At this time, carbon, hydrogen, silicon, etc., which are likely to become positive ions, may be mixed.

That is, since the electrons generated in the plasma state have an extremely high mobility, they can be efficiently collected by the reticulated anode, and it is possible to irradiate only negative ions without irradiating the substrate with unnecessary electrons. .

Further, the substrate negatively self-biased with respect to the mesh anode makes it easy for electrons having a small mass to be collected in the mesh anode. Furthermore, an excessive negative charge near the surface of the substrate, which is formed by irradiation with negative ions, can be expected to have an effect of attracting the above-mentioned unfavorable positive ions, which are easily charged.

The present invention can be applied to the plasma etching method, the plasma CVD method, the plasma film quality modifying method, and any other manufacturing method of a semiconductor device using plasma.

[0016]

EXAMPLE FIG. 1 is a diagram of a semiconductor device manufacturing apparatus used in this example. The silicon substrate 4 was placed on the anode 1 in the reaction chamber and heated to 500 ° C. A reticulated anode 2 made of aluminum is installed on the anode 1. Tetraethoxysilane bubbled with He was introduced from the sample introduction port A of the anode, and oxygen was introduced from the introduction port B of the cathode 3. The ratio of each gas at this time is tetraethoxysilane.
It was 4%, He79.6%, and oxygen20%.

After the pressure inside the reaction chamber was maintained at 1 KPa, a high frequency of 13.56 MHz was applied to generate plasma between the electrodes to form a SiO ₂ film on the substrate. At this time, the anode voltage was 0V and the cathode voltage was -50V.

As a result of analyzing the formed film by infrared spectroscopy,
No organic matter or hydroxyl group was detected, and the film was extremely excellent. It is considered that this is because, due to the action of the reticulated anode, the vicinity of the substrate surface was not irradiated with electrons but was irradiated with only oxygen negative ions, and the reaction between tetraethoxysilane and oxygen was extremely smooth.

[0019]

According to the present invention, in a method for manufacturing a semiconductor device by using a substrate side as an anode and a counter electrode as a cathode to generate high-frequency plasma between both electrodes, the ions irradiated onto the substrate are not positive ions. Since they are negative ions, the chemical reaction near the surface of the substrate progresses extremely smoothly, which is a feature that an extremely excellent semiconductor device can be manufactured. Further, since it is difficult for electrons to be irradiated onto the substrate and only negative ions are irradiated, it is possible to manufacture an extremely excellent semiconductor device.

[Brief description of drawings]

FIG. 1 is a manufacturing device diagram of a semiconductor device for carrying out the present invention.

[Explanation of symbols]

 1 Anode 2 Reticulated anode 3 Cathode 4 Substrate A Sample inlet B Gas inlet

Claims (1)

[Claims] 1. A semiconductor characterized in that a gas containing at least one element of fluorine, oxygen, chlorine, bromine, nitrogen, and hydrogen is put into a plasma state, and negative ions of the element are extracted through a meshed anode. Device manufacturing method.