Semiconductor device manufacturing: process – Making field effect device having pair of active regions... – On insulating substrate or layer
Reexamination Certificate
1998-03-10
2002-07-23
Wilczewski, Mary (Department: 2822)
Semiconductor device manufacturing: process
Making field effect device having pair of active regions...
On insulating substrate or layer
C438S487000, C438S795000, C438S928000, C117S008000, C117S010000, C117S219000, C117S222000
Reexamination Certificate
active
06423585
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a constitution in the case where lamp annealing is utilized as a heating treatment method frequently used in a fabrication process of a semiconductor device. Particularly, the present invention is effective in fabricating a semiconductor device such as a thin film transistor (TFT) on a glass substrate.
2. Description of Related Art
In recent years, development of TFT formed by utilizing a semiconductor thin film (typically thin film whose major component is silicon) on a glass substrate has significantly been progressed. Further, demand of an electrooptical device in which a pixel matrix circuit, a driver circuit, a logic circuit and the like are monolithically mounted on a glass substrate has been promoted.
The most significant restriction caused in forming TFT on a glass substrate is temperature of process. That is, a restriction whereby a heating treatment cannot be carried out at a heat resistant temperature of glass or higher narrows the margin of process.
Therefore, laser annealing process has been utilized as a means for annealing selectively a thin film. According to the laser annealing process, only a thin film can selectively be heated by elevating instantaneously temperature of a sample by irradiating a pulse laser beam onto the sample. However, there has been posed a problem in view of mass production steps in which an optical system is complicated to deal with a laser beam and the uniformity is difficult to ensure.
Hence, a lamp annealing process using a strong beam emitted from an arc lamp, a halogen lamp or the like has recently been spotlighted. This technology is referred to as RTA (Rapid Thermal Annealing) or RTP (Rapid Thermal Processing) in which a film to be treated is heated by irradiating a strong beam in a region of wavelength that is apt to be absorbed by the film to be treated.
Normally, the lamp annealing process utilizes a region of visible light to infrared light as strong beam. The light in this wavelength region is difficult to absorb by a glass substrate and accordingly, the heating of the glass substrate can be restrained to a minimum. Further, time periods for temperature rise and temperature drop are extremely short and accordingly, high temperature treatment at 1000° C. or higher can be carried out in a short period of time of several seconds to several tens seconds.
Further, a complicated optical system such as used in a fabrication process by using a laser beam is not needed and therefore, the process is suitable for treating a comparatively large area with excellent uniformity. Also, the yield and throughput are promoted since the high temperature treatment is basically carried out by a sheet by sheet process.
It is a problem of the present invention to improve the above-described lamp annealing process and to provide a method for effectively subjecting a film to be treated to a heating treatment.
Further, according to the conventional lamp annealing process, light has been irradiated only from an upper face side of a film to be treated and therefore, when a layer which does not transmit the light (for example, electrode made of a metal) or a layer which hinders irradiation of light is present at a portion or a total face of the film to be treated, the film to be treated beneath the layer could not be annealed.
Particularly, when the conventional lamp annealing process was used in a step of activating impurities doped in a semiconductor thin film, an electrode made of a metal and an insulating film which were laminated on the semiconductor thin film hindered irradiation of light and source/drain regions excellent in uniformity could not be formed.
It is one of the problems of the present invention to provide a semiconductor thin film having source/drain regions excellent in uniformity by activating impurities through a step using a heating treatment method improving the conventional lamp annealing process in a semiconductor thin film doped with impurities and by heat treatment at later steps.
SUMMARY OF THE INVENTION
According to a first aspect of the present invention disclosed in the specification, there is provided a heating treatment method which is a method of subjecting a thin film formed on a substrate having a light transmitting performance to a heating treatment by using a lamp light source,
wherein a strong light in a wavelength region capable of subjecting bonds of atoms constituting the thin film to an electron excitation is irradiated from an upper face side of the thin film and simultaneously therewith a strong light in a wavelength region capable of subjecting the bonds to a vibrational excitation is irradiated from a lower face side of the thin film.
In the first aspect of the present invention, the strong light in the wavelength region capable of subjecting the bonds to the electron excitation is a light included in a wavelength region of 10 through 600 nm; and
the strong light in the wavelength region capable of subjecting the bonds to the vibrational excitation is a light included in a wavelength region of 500 nm through 20 &mgr;m.
In the first aspect of the present invention, the strong light in the wavelength region capable of subjecting the bonds to the electron excitation is an ultraviolet light, and
the strong light in the wavelength region capable of subjecting the bonds to the vibrational excitation is an infrared light.
Further, according to a second aspect of the present invention, there is provided a heating treatment method which is a method of subjecting a thin film formed on a substrate having a light transmitting performance to a heating treatment by using a lamp light source,
wherein a strong light in a wavelength region capable of subjecting bonds of atoms constituting the thin film to an electron excitation is irradiated from an upper face side of the thin film and simultaneously therewith a strong light in a wavelength region capable of subjecting the bonds to a vibrational excitation is irradiated from a lower face side of the thin film, and
wherein the strong light in the wavelength region capable of subjecting the bonds to the electron excitation and the strong light in the wavelength region capable of subjecting the bonds to the vibrational excitation are scanned from one end to other end of the substrate in a state of being fabricated in a linear shape.
According to a third aspect of the present invention, there is provided a heating treatment method which is a method of subjecting a thin film formed on a substrate having a light transmitting performance to a heating treatment by using a lamp light source:
wherein a strong light in a wavelength region capable of subjecting bonds of atoms constituting the thin film to an electron excitation and a strong light in a wavelength capable of subjecting the bonds to the vibrational excitation are irradiated from an upper face side of the thin film and simultaneously therewith a strong light in the wavelength capable of subjecting the bonds to the vibrational excitation is irradiated from a lower face side of the thin film; and
wherein the strong light in the wavelength region capable of subjecting the bonds to the electron excitation and strong lights in the wavelength region capable of subjecting the bonds to the vibrational excitation are scanned from one end to other end of the substrate in a state of being fabricated in a linear shape.
In the third aspect of the present invention, an infrared light irradiated from the upper face side of the thin film is irradiated to regions of the thin film immediately before and/or immediately after a region of the thin film where an ultraviolet light is irradiated.
In the second aspect or the third aspect of the present invention, all of the strong light in the wavelength region capable of subjecting the bonds to the electron excitation and the strong lights in the wavelength region capable of subjecting the bonds to the vibrational excitation are scanned in a state of irradiating a same portion of the thin film.
In the second a
Ohtani Hisashi
Yamazaki Shunpei
Fish & Richardson P.C.
Semiconductor Energy Laboratory Co,. Ltd.
Wilczewski Mary
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