JPH0744164B2 - Patterning method - Google Patents

Description

TECHNICAL FIELD The present invention relates to a patterning method.

[Conventional technology and its problems]

With the high integration of devices, more sophisticated miniaturization technology is required. A typical technique for forming a fine pattern is patterning using photolithography. In this technique, a pattern is formed only by applying a photoresist on a film that cuts the pattern, exposing, developing, etching, and removing the resist, and a multi-step process is required. On the other hand, the lift-off method, in which the entire surface is formed on a patterned resist film and then the resist is removed to leave only the pattern portion, has the advantage that an etching step is not required compared to photolithography, but it is less than submicron. It is extremely difficult to form a film evenly in such a fine pattern, and in the case of a complicated shape having adjacent patterns, the pattern is often peeled off in the step of removing the resist.

On the other hand, in pattern formation by laser CVD, the film of the desired pattern can be directly formed by condensing or transferring the laser light, so the pattern formation process can be greatly shortened, and by using a short wavelength laser, submicron It is also possible to form an orderly fine pattern. However, in the case of laser CVD using a photochemical reaction, there is an advantage that low temperature film formation is possible, but there is a serious drawback that vapor phase reaction products accumulate around the pattern. Such accumulation causes electrical troubles such as short circuit and poor contact, which is a serious problem in device manufacturing. As described above, it is extremely difficult to form a fine pattern on the order of submicrons by the conventional method without applying many steps and without disturbing the electrical characteristics.

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

[Means for solving problems]

The present invention forms a protective film different in material from the thin film on the entire surface of a substrate for forming a patterned thin film and capable of being evaporated by laser light, and irradiating the protective film with laser light in a desired pattern shape from above. A patterning method, characterized in that after the protective film is evaporated, the thin film is formed by decomposing the raw material gas with the laser beam, and the protective film is removed after the film formation.

[Action]

In photo-CVD, where the gas-phase reaction plays a central role, even if a patterned thin film is formed by irradiating light with a desired pattern shape, a deposition due to the gas-phase reaction occurs around the pattern, but only the desired pattern formation part on the substrate. If the film is exposed and the other part is covered with a cover film made of a material different from that of the pattern thin film, the accumulation due to the gas phase reaction around the pattern falls on the cover film. After forming the pattern, the pattern thin film is not etched, and the surface of the substrate is etched using an etchant that etches the cover film, so that the accumulation around the pattern is removed together with the cover film.

The present invention utilizes this, to form a cover film different from the pattern thin film on the entire surface of the substrate to be patterned in advance, and then form a pattern of the cover film with a laser beam having a desired pattern shape used for CVD. The substrate is exposed by ablating the area, and then CVD is performed.When the desired film thickness is obtained, the cover film is etched and the pattern thin film is not etched.The cover film is etched with an etchant. As a result, a patterned thin film having no accumulation in the peripheral portion can be obtained.

In the present invention, the steps of exposing, developing, and etching the resist, which are necessary for ordinary photolithography, are not necessary, so that the number of steps can be greatly reduced.

It is also possible to form a submicron-order pattern with a short wavelength laser. In addition, since there is no accumulation of gas phase reaction products around the pattern, which is a problem in CVD using ordinary laser or light other than laser, there is no problem in the electrical characteristics of the device.

In the present invention, the raw material gas may or may not be stopped when the film for the cover is ablated. However, when the irradiation light intensity required for CVD is significantly different from the irradiation light intensity required for ablation, it is necessary to change the irradiation light intensity according to the process.

〔Example〕

Hereinafter, embodiments in which the present invention is applied to the formation of a patterned thin film of amorphous silicon will be described in detail with reference to the drawings.

FIG. 1 is a schematic diagram showing a state in which an AZ1350 resist film 2 serving as a cover film for a portion other than a pattern film is applied on a substrate 1. After forming the AZ1350 resist film 2 in this way, the substrate 1 is placed in the CVD chamber 4 at 150 ° C. as shown in FIG.
It is installed on the heater 6 whose temperature has been raised to a certain degree. A raw material gas for forming amorphous silicon, disilane, is flowed, and the light of the ArF laser 5 is irradiated through the pattern mask 7, the lens 8 and the synthetic quartz window 9 to ablate the AZ1350 resist film 2 into a pattern shape, and then on the exposed surface of the substrate 1. To laser CV
An amorphous silicon thin film pattern 3 is formed by D. When the desired film thickness is obtained, the substrate 1 is taken out from the CVD chamber 4 and the AZ1350 resist film 2 is removed with acetone as shown in FIG. Since the deposit around the pattern is also removed together with this AZ1350 resist film 2,
It is possible to obtain a pattern of amorphous silicon having no accumulation around the pattern.

In the present invention, the current state of the resist and the etching for forming the pattern are not required, so that the number of steps can be significantly reduced as compared with the ordinary photolithography. Also, ArF
Since the laser wavelength is 193 nm and pattern transfer in the submicron order is possible, it is possible to form a much finer pattern than the usual lift-off method in which a film is collectively formed on a resist pattern. Further, in the present invention, since the deposit around the pattern is removed together with the resist film, the deterioration of the electrical characteristics due to the deposit, which is a problem in forming the pattern thin film only by the laser CVD, does not occur.

In this embodiment, the resist film is used as the film for covering the area other than the pattern forming portion, but the film for the cover does not necessarily have to be the resist. Si as the film for the cover
Patterning is also possible by using O ₂ and using buffered hydrofluoric acid as the etchant. However, the laser light intensity required for ablation of SiO ₂ is several tens of MW / cm ² , and the irradiation light intensity required for deposition of amorphous silicon is 0.01 to 0.1 MW / cm ^2.
It is much higher than that of the ablation process and CV.
It is necessary to change the intensity of laser light in the process of D. Further, in the present embodiment, only the pattern state by pattern transfer is described, but the applicable range of the present invention is not necessarily limited to the case of pattern transfer. The same applies to the case of pattern formation by direct drawing. In this case, the present invention can be applied only by changing the device such as mounting the chamber on the XY stage instead of the optical system for condensing the laser light.

[Effects of the Invention] As described above, according to the present invention, it is possible to easily obtain a fine patterned thin film that does not accumulate on the periphery in a small number of steps.

[Brief description of drawings]

FIG. 1 is a sectional view showing a state where a resist film is formed on a substrate, FIG. 2 is a sectional view of an apparatus for forming a silicon thin film pattern by laser CVD, and FIG. 3 is a state in which a silicon thin film pattern is formed by the present invention. FIG. 1 ... Substrate, 2 ... AZ1350 resist film, 3 ... Amorphous silicon thin film pattern, 4 ... CVD chamber, 5 ...
… ArF laser, 6 …… Heater, 7 …… Pattern mask,
8 ... Lens, 9 ... Synthetic quartz window.

Claims (1)

[Claims] 1. A protective film, which is made of a material different from that of the thin film and which can be evaporated by laser light, is formed on the entire surface of a substrate on which a patterned thin film is formed, and the desired pattern is irradiated with laser light from above the protective film. After the protective film is evaporated, the thin film is formed by decomposing the raw material gas with the laser light, and the protective film is removed after the film formation.