JPH01315140A - Plasma treatment and apparatus - Google Patents

Abstract

PURPOSE:To enhance treatment efficiency and to make a treatment proper by a method wherein a face to be treated is irradiated with electromagnetic waves of a specific wavelength exciting an interatomic bond oscillation of a constitutive atom of a substrate to be treated or a formation film. CONSTITUTION:A silicon wafer is used as a substrate 1 to be treated; a silicon oxide film is formed. Oxygen is introduced into a plasma generation chamber 4 through a first gas introduction tube 5; in addition, microwaves 6 are introduced into the plasma generation chamber. In addition, a magnetic field is generated by using a field generation coil 9; a plasma stream 10 is generated; monosilane is introduced from a second gas introduction tube 11. When a film is deposited, a speed and the film quality such as denseness or the like of the deposited film are governed by a level of energy of an interatomic oscillation, rotation, translation and the like of a plasma species which has reached a face of the substrate to be treated. By this setup, a plasma treatment can be enhanced and the plasma treatment can be made proper without heating the substrate.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method and apparatus for manufacturing an electronic device, particularly in film formation and plasma doping.
The present invention relates to a plasma processing method and apparatus suitable for improving processing efficiency and optimizing processing.

[Conventional technology]

As a method of depositing a thin film using plasma, Japanese Patent Application Laid-Open No. 1987-
As described in No. 202739, a method of using a laser beam for plasma generation or substrate heating, and Japanese Patent Laid-Open No. 57
As described in No. 202740 and No. 60-117711, there is a method in which a substrate is irradiated with X-rays or ultraviolet light during plasma processing to improve the processing efficiency of film formation.

[Problem to be solved by the invention]

The above conventional techniques do not take into account heating the substrate with a laser beam or exciting the electron energy of constituent atoms of the substrate or thin film in order to accelerate the reaction with plasma species and increase the deposition rate of the thin film. However, the mechanism of thin film formation and the diffusion of plasma species to the substrate were not considered, and as a result, increasing the deposition rate of the thin film resulted in the problem of deterioration of film quality and the efficiency of film formation and doping due to plasma oxidation, etc. However, there was a problem in that it did not significantly improve when compared with simply plasma processing.

An object of the present invention is to improve the above-mentioned disadvantages.

[Means to solve the problem]

The feature of the present invention for the above-mentioned purpose is achieved by irradiating the surface to be processed with electromagnetic waves of a specific wavelength that excite vibrations of the interatomic bonds of constituent atoms of the substrate to be processed or the formed film during plasma processing. Ru.

Another feature of the present invention is a plasma processing apparatus having a mechanism for irradiating the object to be treated with the electromagnetic waves during plasma processing.

Another feature of the present invention will become clear from the following description.

[Effect]

In film deposition, the speed and film quality such as the density of the deposited film are controlled by the energy level of the two rotations and translations of interatomic vibrations of the plasma species that have reached the surface of the substrate to be processed. If this energy is high, not only will the reaction efficiency of the plasma species that have reached the substrate increase, but also the atoms or molecules that have previously been formed on the substrate will be rearranged to the alignment or reorientation position where the energy is minimum. Since the probability of reorientation and reorientation movement increases, the deposition rate increases and the quality of the film also improves. Interatomic vibrational energy dissipates rapidly into rearrangement and reorientation kinetic energy. Therefore, in other words, if atomic vibration energy is applied to a layer that has been formed on a substrate in advance, the deposition conditions of the plasma species that will be deposited later will be optimized, which will improve the deposition rate and improve the quality of the deposited film. Quality such as precision is improved. At this time, if the base substrate is made of a material with a low vapor pressure, such as GaAs, light that excites the vibrations of the constituent atoms of Ga-As or the like is irradiated.

As a result, the substrate is heated and damaged, so in such a case, only the formed film is excited without exciting the substrate. For example, if the deposited film is 5iOz, only 5i-0 vibration is generated. It is desirable to irradiate with infrared light of 1080 [cm-11] for excitation.

In film formation by plasma oxidation or plasma doping, the processing efficiency is proportional to the diffusion efficiency from the substrate surface and the reaction efficiency of interatomic junctions in the diffusion region. Diffusion is positively dependent on the bond spacing between the atoms that make up the substrate. Also,
Vibrational transition involved in bonding v==n→v=n+1. n+
3. n+4...(n is vibrational level, n''O* 1
g 2 HV ' The smaller V, the higher the transition probability.)
According to the Frank-Conton principle, even if the electronic state of the reaction system between the substrate constituent materials and the plasma species is a metastable state that does not directly lead to a reaction, there is a high probability that dissociation and bonding reactions will occur. Therefore, the reaction rate improves.

Therefore, when the interatomic bond vibrations of the substrate constituent material are excited, the interatomic bond distance increases, and the efficiency of plasma processing improves based on the Frank-Conton principle. At this time, if there is a mask material on the surface of the substrate, if the mask material is excited by vibration, the mask will undergo plasma treatment, mainly etching or deterioration, so the irradiation light will not excite the mask material and the substrate structure It is desirable to irradiate light that excites only the vibrations of atoms.

〔Example〕

EMBODIMENT OF THE INVENTION Below, one embodiment of the present invention will be described in detail using the drawings.

FIG. 1 is a sectional view of the main parts of the plasma processing apparatus of the present invention. This apparatus uses a microwave plasma method using electron cyclotron resonance to generate plasma species. Plasma generation chamber 4. Microwave waveguide 7 (the oscillator of the microwave 6 is omitted from the figure), magnetic field generating coil 9° processing chamber 2. Exhaust port 12 (exhaust system not shown) 9 Reactive gas supply pipes 5 and 11 (reactive gas supply system not shown),
Board support stand 3. Infrared globe lamp 13. Concave reflector 14. Interference filter 159 Reflector 16° Infrared transmission window 1
Consists of 7. Plasma generation chamber 4 has a diameter of 240 (+m)φ
It is made of quartz and has a length of 250 (ml), and the conical top serves as the microwave introduction window 8.The magnetic field generation coil is installed around the plasma generation chamber, and the maximum magnetic flux density is 1.2 (KGa).
The processing chamber 2 is made of stainless steel and has a diameter of 370 (am) φ, and the substrate support stand 3 installed inside has a diameter of 12 mm.
Made of alumina with a diameter of 0 (m), the substrate can be heated up to 300 ('C)
It can be heated up to. To irradiate the substrate with infrared rays 18, a global lamp 13 generates infrared rays, a concave reflector 14 condenses the infrared rays into parallel rays, an interference filter 15 obtains infrared rays of a desired wavelength, and a reflector 16 emits the infrared rays. The measurement was conducted through an infrared transmitting window made of KR8S, which is a thallium chloride material.

Example 1 A silicon wafer (diameter 100 (n)
a) φ) to form a silicon oxide film (Si(h). Oxygen was introduced into the plasma generation chamber 4 through the first gas introduction pipe 5 at a rate of 40 Cm Q /win),
GHz) microwave 6 is introduced into the plasma generation chamber,
And 875 (Gauss) by the magnetic field generating coil 9
Generate the above magnetic field to generate the plasma flow 10,
6 limonosilane (SiHa) from the second gas introduction pipe 11
(m Q /win) was introduced, and the pressure inside the processing chamber 2 was set to 3 (mtorr) by the exhaust system. Initially, deposition was performed without substrate heating and infrared irradiation, and the deposition rate was 50 (n m /win), and the deposited film was etched with a buffered hydrofluoric acid solution (HF:NH4F=1:4) at an etch rate of 1.0 (μm/inch). 'C) and deposited in the same manner, the deposition rate was 40 (nm/m1nl) and the etch rate was 0.5 [μm/win].
Deposition was carried out in the same manner while irradiating infrared rays without heating the substrate.

Infrared light was used by using an interference filter to separate light with a wave number of 1060 to 1100 [cs-'] that excites Si-○ vibrations. The deposition rate at this time was 70 (n
m/win), the etch rate is 0.15 [μm/w
in). The substrate temperature when deposited while irradiating the substrate with infrared rays was 120 ("C) as measured with thermo tape.
The etch rate indicates the density of the film, and the slower the etch rate, the denser the deposited film. For example, 10
The etch rate of the film formed by thermal oxidation at 00'C is 0.
1 [μm/win]. From the above results, it was found that plasma treatment while irradiating with infrared rays increases the deposition rate and also improves the density of the film. It was found that this infrared irradiation effect was not caused by heating the substrate, but by exciting the vibrations of the 5iOz film and depositing it.

The wavelength of the infrared rays may be 25 μm or more.

Example 2 A silicon wafer (<100> plane) was used as the substrate 1 to be processed.
An oxide film was formed by plasma irradiation.

100 (m Q
/win), and the pressure was Q, 8 (+torr). Other conditions are the same as in Example 1.

FIG. 2 is a diagram showing the time change in the thickness of the formed film at this time. A is a curve showing the time dependence of the formed film thickness under the experimental conditions of only plasma treatment, B is plasma treated soil substrate heating, and C is plasma treatment + infrared irradiation. As can be seen from these results, it was found that when plasma oxidation is performed while irradiating infrared rays, the processing efficiency increases significantly and is greater than the effect of heating the substrate.

Example 3 The substrate to be processed 1 is n-type ((100>plane 12 [Ωl])
Doping using B2H8 plasma irradiation was performed for 90 minutes using a silicon wafer. 50 (mff/win) of B2H8 was introduced through the first gas introduction pipe at a pressure of 0.5 (mtorr). Other conditions are the same as in Example 1. Figure 3 is a diagram showing the doping profile at this time, where A is only the plasma treatment and B is the doping profile.
1 shows the concentration profile of B in the depth direction of the substrate by heating the plasma-treated soil substrate, and C shows the plasma treatment + infrared irradiation. The irradiated infrared rays are 5i-3
610 [a1″″ which is one wave number of the standard bending vibration of i
It is one line. As can be seen from FIG. 3, it has been found that when plasma doping is performed while irradiating infrared rays, the processing efficiency increases significantly, which is greater than the effect of heating the substrate.

According to this example, in film deposition, oxidation, and other film formation by plasma irradiation, and plasma doping, performing plasma treatment while irradiating the substrate with infrared rays has the effect of increasing processing efficiency and optimizing processing. I found out something.

In this embodiment, a microwave plasma method was used to generate the plasma species, but other high frequency excited plasma methods such as RF plasma may of course be used. Moreover, although an interference filter is used for spectroscopy, it is of course possible to use a single diffraction grating, a prism, or the like to perform spectroscopy.

〔Effect of the invention〕

According to the present invention, plasma processing is improved and plasma processing is optimized without heating the substrate, so that compound semiconductor devices, which are particularly sensitive to temperature rises, can be manufactured with high efficiency.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of the plasma processing apparatus of the present invention, FIG. 2 is a diagram showing the time dependence of plasma oxide film thickness, and FIG. 3 is a diagram showing the depth direction dependence of B concentration due to plasma doping. It is. DESCRIPTION OF SYMBOLS 1... Substrate to be processed, 6... Microwave, 9... Magnetic field generation coil, 13... Infrared light source, 15... Interference filter, 17... Infrared transmission window, A... Plasma treatment only, B... Plasma treated soil substrate heating, C... Plasma treated land 2 drawings, building 3 concave

Claims (1)

[Claims] 1. In a method of treating the surface of a substrate to be processed with a plasma species, electromagnetic waves of a specific wavelength are used to excite the vibrations of interatomic bonds constituting the substrate to be processed or a film formed on the substrate to be processed. A plasma processing method characterized by performing plasma processing while irradiating a surface to be processed. 2. The plasma processing method according to claim 1, wherein electron cyclotron resonance is used to generate plasma species. 3. The electromagnetic waves mentioned above are caused by stretching vibrations between bonded atoms, bending vibrations,
Claims 1 or 2, characterized in that it has a wavelength that excites at least one of a fundamental tone, overtones, or combined tones of a plurality of vibration modes that excites torsional vibrations. Plasma treatment method. 4. In an apparatus that processes the surface of a substrate to be processed with a plasma species, an electromagnetic wave of a specific wavelength that excites the atomic photocoupling vibration that constitutes the substrate to be processed or a film formed on the substrate to be processed is applied to the surface to be processed. A plasma processing device characterized by being able to perform plasma processing while irradiating. 5. Optical interference filter to obtain the above electromagnetic waves. 5. The plasma processing apparatus according to claim 4, which uses a cut filter, a slit, a prism, a diffraction grating, or an echelon grating. 6. In order to allow the electromagnetic waves to reach the surface to be treated in the plasma processing vessel, thallium iodide-based materials, compounds of halogen elements and alkali metals, compounds of halogen elements and alkaline earth metal elements, zinc sulfide-based materials are used. The plasma processing apparatus according to claim 4 or 5, characterized in that the vacuum vessel is made of at least one material selected from the group consisting of selenium and zinc-based materials. 7. The plasma according to any one of claims 4 to 6, wherein a thermal radiation lamp, a discharge lamp, a laser, or a synchrotron radiation light is used as the electromagnetic wave. Processing equipment. 8. The plasma processing apparatus according to claim 6, wherein the vacuum container has a window.