JP2921240B2 - Oxide film pattern forming method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a film forming method, and more particularly to an oxide film pattern forming method.

[0002]

2. Description of the Related Art An SiO ₂ pattern is formed on a Si surface by:
It is an important technology used for the purpose of forming a gate oxide film, separating elements, dry etching mask of Si, and the like. Conventionally, this patterning has been performed through multi-step processes such as thermal oxidation of Si, photolithography, and etching. Such a multi-step process is not only complicated, but in the case of manufacturing a display substrate, etc.
This may lead to a risk of damaging the T element, which is a major obstacle in improving productivity. As a method to shorten the process,
Formation of SiO ₂ film by laser CVD that can be directly patterned without using photolithography is the journal of applied physics Vol. 69, No. 3
1744-1747. However, in this method, the patterning region that can be formed by one laser CVD is limited to the size of the laser beam.
In order to perform patterning over the beam area, the substrate,
Alternatively, the productivity is very low because sweeping of a laser beam is required.

[0003]

As described above, the conventional method using photolithography requires many steps, and it is difficult to avoid damage to the device, so that sufficient productivity cannot be obtained by laser CVD. .

An object of the present invention is to provide a film forming method which solves the problems of the conventional method.

[0005]

According to the present invention, there is provided a patterning method for forming an oxide film pattern on a Si surface, comprising the steps of immersing a substrate in a hydrofluoric acid solution for a predetermined time and terminating hydrogen; Irradiating the surface of the substrate with a laser beam in a pattern to remove hydrogen from the substrate in a desired pattern shape; and thereafter, oxidizing a portion from which hydrogen has been removed in the step. And

[0006]

[Function] When Si is immersed in hydrofluoric acid, the surface is terminated with H. Applied Physics Letters Vol. 53
No. 11, page 998. Oxygen and H are compared with those without the hydrogen-terminated Si surface.
Difficult to adsorb ₂ O etc. Therefore, the activation energy of the oxidation is higher than that of the portion where the hydrogen termination is not performed, and the oxidation is hardly performed. Hydrogen termination is destroyed by laser light irradiation, substrate heating, etc.
Hydrogen desorbs from the substrate. The present invention utilizes this fact to obtain a desired oxide film pattern by hydrogen terminating the surface of the Si film, irradiating a laser beam to a portion to be oxidized, desorbing hydrogen, and then oxidizing the surface. . Further, if the same process is performed on a Si film on a quartz or glass substrate and then dry etching of Si is performed using an oxide film pattern as a mask, an island pattern of Si can be formed. Can be applied to the formation of a TFT matrix. In this case, since the SiO ₂ film on Si can be used as a gate oxide film, it is not necessary to remove it as with a normal resist.

In the present invention, since photolithography is not used for forming the SiO ₂ pattern, the number of steps is significantly reduced, and damage due to resist peeling does not occur. In addition, since laser irradiation can be performed for a time necessary to destroy hydrogen termination, the time required for laser irradiation can be significantly shorter than when an SiO ₂ film or a Si film is formed by laser CVD.
As a whole, productivity comparable to that of the conventional method using photolithography can be obtained.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Formation of MOSFET gate insulating film and Si
An embodiment in which the method according to the present invention is applied to the formation of islands will be described in detail with reference to the drawings.

FIGS. 1 to 3 are schematic views showing formation of a gate insulating film of a MOSFET according to the present invention. The substrate 1 is immersed in 1% HF for about 1 minute, and the surface is hydrogen-terminated as shown in FIG. After being lifted from the HF solution and dried by a spinner, as shown in FIG. 2, an ArF excimer laser 2 is irradiated on a portion of the substrate 1 where a gate insulating film is to be formed for several seconds, and the portion is terminated. Desorbed hydrogen. Subsequently, as shown in FIG. 3, the substrate 1 is fixed on the upper portion of the heater 4 inside the vacuum chamber 3, and the temperature of the heater 4 is maintained at 200 ° C. to 300 ° C. O ₂ gas is supplied to the vacuum chamber 3 and the pressure is maintained at about several mTorr. By setting the oscillation frequency of the RF power supply 5 to 13.56 MHz and continuing the plasma excitation for about 1 hour,
2000 Angstrom thick Si only in the hydrogen desorbed area
O ₂ could be formed selectively.

FIGS. 4 to 7 are schematic diagrams showing the formation of a Si island in a TFT matrix according to the present invention. The method for terminating the hydrogen on the glass substrate 6 shown in FIG. 4 is the same as that for forming the gate insulating film. After the hydrogen termination, the glass substrate 6 is fixed to the XY stage 8 as shown in FIG. 5, the emitted light of the ArF laser 2 is irradiated on the glass substrate 6 through the pattern mask 7, and the XY stage 8 is driven. A matrix-shaped hydrogen desorption pattern is formed. Subsequently, as shown in FIG.
The hydrogen desorbed portion is selectively oxidized as in the case of (1). Finally, as shown in FIG. 7, dry etching using CF ₄ as an etchant was performed using the oxide film formed in FIG. 6 as a mask to obtain a Si island matrix.

In each of the above two embodiments, the light source is an ArF laser, but it is not necessarily limited to this. KrF that can induce hydrogen desorption in a short time
Any light source such as a laser or an Ar laser can be applied. The method of oxidation is not necessarily limited to plasma oxidation. Any oxidation method that can be realized at a low temperature that does not destroy the hydrogen terminate can be applied. For example, thermal oxidation using ozone gas can be applied to the present invention.

Since photolithography is not used in the present invention, the number of steps can be reduced. Also, the formation time of the dry etching mask is much shorter than when the a-Si island is formed directly by laser CVD, so that the throughput is greatly improved.

[0013]

As described above, according to the method of the present invention, a SiO ₂ pattern can be formed in a small number of steps, and a TFT matrix can be formed with high productivity.

[Brief description of the drawings]

FIG. 1 is a schematic view showing formation of a gate insulating film of a MOSFET according to the present invention.

FIG. 2 is a schematic diagram showing formation of a gate insulating film of a MOSFET according to the present invention.

FIG. 3 is a schematic diagram showing formation of a gate insulating film of a MOSFET according to the present invention.

FIG. 4 is a schematic diagram showing the formation of a Si island in a TFT matrix according to the present invention.

FIG. 5 is a schematic view showing the formation of a Si island in a TFT matrix according to the present invention.

FIG. 6 is a schematic diagram showing the formation of a Si island in a TFT matrix according to the present invention.

FIG. 7 is a schematic diagram showing the formation of a Si island in a TFT matrix according to the present invention.

[Explanation of symbols]

 Reference Signs List 1 substrate 2 ArF laser 3 vacuum chamber 4 heater 5 RF power supply 6 glass substrate 7 pattern mask 8 XY stage

Claims (1)

(57) [Claims] In a patterning method for forming an oxide film pattern on a Si surface, a substrate is exposed to a hydrofluoric acid solution for a predetermined time.
A step of immersing and hydrogen terminating, and irradiating the surface of the substrate subjected to the step with a laser beam in a pattern,
A method for forming an oxide film pattern, comprising: a step of removing hydrogen from the substrate into a desired pattern shape; and thereafter, a step of oxidizing a portion from which hydrogen has been removed in the step.