JPH0628235B2 - Method for forming bit pattern of thin film device - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for forming a bit pattern of a thin film device by a photoexcited CVD method.

2. Description of the Related Art Conventionally, a CVD method (chemical vapor deposition method) is known as a method for forming a thin film semiconductor device. As one of them,
Recently, a photo-excited CVD method, which uses light energy to form a thin film from a gas material, has attracted attention.

Here, in a thin film device, for example, an a-Si equal-magnification photosensor using an a-Si: H film as a photoconductive material, a-Si:
It is necessary to form the bit pattern of the H film with a predetermined pitch. Then, there is the following method as a method of simultaneously forming a bit pattern in the reaction chamber when a thin film is formed by the photoexcited CVD method without using a photolithography process.

FIG. 3 shows an example thereof. First, the glass substrate 2 is placed on the susceptor 1 made of silicon or the like, and the glass substrate 2 is heated to about 300 to 200 ° C. from the susceptor 1 side by the light source 4 arranged outside the reaction chamber 3. And
A metal mask 5 having a desired bit pattern formed thereon is brought into close contact with the glass substrate 2 on which an a-Si: H film is to be deposited. Then, Si _{2 is used} as a source gas in the reaction chamber 3.
H ₆ gas is flowed, and ultraviolet monochromatic light UV (ArF laser-light 193 is applied from the upper surface of the glass substrate 2 to which the metal mask 5 is adhered.
nm or low pressure mercury lamp 253 nm). Thus, ultraviolet monochromatic light UV is absorbed in Si ₂ H ₆ to decompose the Si ₂ H ₆ gas, a-Si on a glass substrate 2 is adhered to the metal mask 5: bit pattern H film is formed It However, since the precision of the bit pattern is determined by the precision of the metal mask 5, a precise metal mask is required. Therefore, it is not possible to cope with the miniaturization and lengthening of bit patterns in recent years.

On the other hand, there is also a method of forming a bit pattern by sequentially irradiating only the bit pattern forming portion on the substrate with laser light without using a metal mask. However, such a scanning method is time consuming and inefficient.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a method for forming a bit pattern of a thin film device capable of efficiently forming a highly accurate bit pattern without using a metal mask. .

Configuration One embodiment of the present invention will be described with reference to FIGS. 1 and 2. This embodiment utilizes the interference of ultraviolet monochromatic light used in the photo-excited CVD method.

First, the principle will be described with reference to FIG. The glass substrate 2 is placed on the susceptor 1 made of silicon or the like, and the glass substrate 2 is heated to about 300 to 200 ° C. by the light source 4. Then, Si ₂ H ₆ gas is flown into the reaction chamber 3 as a source gas. Note that He may be used as a diluent gas and N ₂ may be used as a carrier gas. Therefore, ultraviolet monochromatic light UV is irradiated for decomposition of Si ₂ H ₆ gas based on the photo-excited CVD method, and the irradiation method has a feature of the present invention. That is, the ultraviolet monochromatic lights UV ₁ and UV ₂ (ArF laser-light 193 nm or low-pressure mercury lamp 253 nm, etc.) split into two by the beam splitter are irradiated from two directions toward the glass substrate 2 at an intersection angle θ. It is a thing. Here, the two optical paths of the ultraviolet monochromatic lights UV ₁ and UV ₂ are set so as to match on the surface of the glass substrate 2.

In this way, by introducing the ultraviolet monochromatic lights UV ₁ and UV ₂ from two directions so as to cross each other, and letting the wavelength be λ, interference of two rays causes interference of light and darkness on the surface of the glass substrate 2 with a pitch of λ / sin θ. A pattern is formed. In this bright and dark pattern, in the bright pattern portion, the light irradiation causes decomposition of Si ₂ H ₆ gas on the surface of the glass substrate 2,
An a-Si: H film is deposited on the surface of the glass substrate 2 which has been heated to an appropriate temperature in advance. That is, only the bright pattern portion is deposited to form a bit pattern. In this way, the glass substrate 2 can be used without using a metal mask.
The bit pattern of the a-Si: H film corresponding to the light interference intensity image formed above is directly formed. According to this method, the formation is faster and more efficient than the laser light scanning method. Further, since the two light rays UV ₁ and UV ₂ are focused on the surface of the glass substrate 2, the decomposition rate of the Si ₂ H ₆ gas on this glass substrate 2 is the highest and the introduction of the reaction chamber 3 into which the light is introduced is introduced. Since the decomposition rate of Si ₂ H ₆ gas on the window wall is low, the light introduction window is less likely to be clouded by deposits.

By the way, in actual implementation, as shown in FIG. 2, an ultraviolet monochromatic light UV emitted from a light source 6 such as a laser light source is converted into an ultraviolet monochromatic light UV ₁ , U by a beam splitter 7.
By dividing into _two as V ₂ , and passing one of the ultraviolet monochromatic light UV ₁ through the reflecting mirror 8, the two rays UV ₁ and UV ₂ are irradiated from two directions toward the glass substrate 2. Here, the pitch of the light and dark pattern due to the interference of light is λ / sin
Since it is θ, by adjusting the crossing angle θ of the two light rays UV ₁ and UV ₂ by the reflecting mirror 8, it is possible to irradiate the glass substrate 2 with light so that a bright and dark pattern corresponding to a desired bit pattern is generated. it can. In the drawings, the first
The figure is for showing the principle of light interference, and FIG. 2 is for showing a more actual device. Therefore, although the size of the crossing angle is different, the crossing angle θ is used in the same meaning. To do.

By the way, in this embodiment, the monochromatic ultraviolet light is applied from the front surface side of the substrate 2 on which the thin film is to be formed. However, if the substrate does not absorb the monochromatic ultraviolet light, the monochromatic ultraviolet light is emitted from the rear surface side of the substrate. The light path may be set so that the light is irradiated from two directions and the light beams match with each other on the surface of the substrate.

Effect As described above, the present invention is provided so that the ultraviolet monochromatic light for decomposing the raw material gas is split by the beam splitter and introduced from the light introducing window into the reaction chamber from two directions and separated from the light introducing window. The optical paths are set so that they match on the substrate surface, and the bit pattern is formed by the light and dark patterns resulting from the interference of the ultraviolet monochromatic light from these two directions, so based on the light and dark patterns due to the light interference. The bit pattern of the deposit can be directly formed on the surface of the substrate, and thus the accurate bit pattern can be efficiently formed without using a metal mask, and the monochromatic ultraviolet light is introduced from the introduction window wall. Since the light is introduced into the reaction chamber from two directions and the surface of the substrate is provided away from the introduction window wall, the light introduction window is prevented from being clouded by deposits.

[Brief description of drawings]

FIG. 1 is a schematic front view showing the principle of one embodiment of the present invention, FIG. 2 is a schematic front view showing the setting of the crossing angle, and FIG. 3 is a schematic front view showing a conventional method. 2 ... Substrate, 3 ... Reaction chamber, 7 ... Beam splitter

Claims (1)

[Claims] 1. An ultraviolet monochromatic light for decomposing a raw material gas is split by a beam splitter and introduced into a reaction chamber from a light introducing window in two directions, and on a substrate surface provided away from the light introducing window. Photoexcitation C characterized in that the optical paths are set so as to coincide with each other, and a bit pattern is formed by a light-dark pattern resulting from the interference of ultraviolet monochromatic light from these two directions.
A method for forming a bit pattern of a thin film device by the VD method.