JPH0823686B2 - Laser mask - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a laser mask, and more specifically, a laser marking mask suitable for use in a laser marking device which replaces a conventional printing method in a character marking step of IC production. It is about.

[Problems to be Solved by Conventional Techniques and Inventions] Conventionally, the character marking process in IC production has been performed by a printing method, but it takes time to produce, and steps such as pretreatment and cleaning are required. Therefore, in order to improve productivity, a marking technique using a laser instead of the conventional method has been studied. However, what has been studied so far is that since a metal plate 7 as shown in FIG. 3 is used as a mask, it is necessary to attach a bridge 8 as shown in FIG. It had the drawback of being distorted.

The present invention has been made in view of such conventional problems, and an object thereof is to provide a laser mask capable of performing marking without distortion.

[Means for Solving the Problems] In order to achieve the above object, the laser mask of the present invention has a patterned three-layer structure in which a chromium film, a copper alloy film, and a copper film are laminated in this order on a quartz glass substrate. And a patterned silicon dioxide film formed on the reflective film. Also, an antireflection film may be further provided on the surface of the mask and the surface on the reflection film side.

[Operation] By performing marking with a laser using the laser mask of the present invention, a bridge is not needed in an image portion (character portion) like a conventional metal plate, and distorted characters are eliminated. Further, by forming the reflective film into a three-layer structure of a metal film, the adhesion, corrosion resistance, and etching shape (prevention of chipping) can be improved. Furthermore, by providing a silicon dioxide film on the reflective film to prevent discoloration of the reflective film, mass production and storage as a blank is possible if the steps up to this point are completed. It is possible to quickly respond to, and the quality is stable. Further, if an antireflection film is further provided on the surface of the mask on the reflection film side, reflection of laser light on the substrate of the image portion (light transmitting portion) is prevented and the edge portion of the image is protected.

[Specific Description of the Invention] The present invention will be described in more detail below.

FIG. 1 is a cross-sectional view showing the structure of a mask blank used for manufacturing the laser mask of the present invention, in which a chromium film 2a, a copper alloy film 2b and a copper film 2c are formed on a quartz glass substrate 1.
Is provided in this order to form a three-layered reflective film 2, and a silicon dioxide film 3 is further provided thereon.

Here, the quartz glass substrate 1 is a material that is optically transparent to the laser light, and there is no essential limitation on the thickness thereof, but a material of about 0.2 to 6 mm is usually used.

Further, the reflection film 2 has a three-layer structure in which the chromium film 2a, the copper alloy film 2b and the copper film 2c are laminated in this order as described above, but a certain optical density ( Generally, 2.6 to 3.0) is required. The light-shielding property referred to here is a light-shielding property with respect to laser light. The film thickness required to have this optical density is a chromium film
2a, since the copper alloy film 2b and the copper film 2c may be secured in the entire three layers, the film thickness of each layer can be arbitrarily determined, respectively, in the present invention, the chromium film 2a is mainly adhesive, copper alloy Since the film (for example, an alloy of copper and aluminum) 2b mainly has a light-shielding property and adhesiveness, and the copper film 2c mainly has a function of preventing static electricity, specifically, the preferable film thickness of the chromium film 2a is Any thickness is acceptable as long as it has adhesiveness, copper alloy film
The preferable film thickness of 2b depends on the laser wavelength, but it is 2000
The thickness is Å or more, and the preferable film thickness of the copper film 2c is 400 Å or more, although it depends on the required charging degree. Quartz glass substrate 1
To form this reflective film 2 on the surface, for example, magnetron sputtering, vacuum deposition, ion plating, CV
Any conventionally known thin film forming method such as the D method can be adopted. In particular, it is preferable that the three layers forming the reflection film 2 be formed continuously (for example, continuous sputtering) because foreign matter is not mixed in during the process. The formed three-layer reflective film 2 can be patterned by, for example, dry etching.

The silicon dioxide film 3 prevents discoloration of the reflective film 2, and its thin film is preferably 2000 liters or more. To form the silicon dioxide film 3, the same method as that for forming the reflective film 2 can be used. Further, the silicon dioxide film 3 can be patterned together with the reflection film 2 by dry etching.

Next, an example of a method for manufacturing a laser mask using the mask blank having the structure shown in FIG. 1 will be described with reference to FIGS.
It will be described based on (c).

After the surface of the mask blank is washed as necessary, a photosensitive resin is applied to expose a desired pattern and then developed to form a patterned resist layer 4 (see FIG. 2 (a)). Next, the silicon dioxide film 3 and the reflective film 2 are patterned 3'and 2'by dry etching (see FIG. 2B). After that, the remaining resist layer 4 is removed to obtain a laser mask (see FIG. 7C). In the figure,
Reference numeral 5 indicates that the laser light passes through the non-light-shielding portion.

Further, as shown in FIG. 2D, it is desirable to provide an antireflection film 6 on the outermost surface of the completed mask on the reflection film side. By doing so, it is possible to prevent the laser light from being reflected by the substrate of the image part (non-light-shielding part) 1a and to effectively use the irradiation light, and also to protect the edge part of the image and also to have an anticorrosion effect. The material of the antireflection film 6 is not particularly limited as long as it has antireflection properties for the laser light used. When the laser wavelength is 1.06Å, TiO ₂ may have a two-layer structure of 277Å and SiO ₂ 2309Å or a SiO ₂ single layer film. The optimum reflection characteristics differ depending on the wavelength. For a laser wavelength of 1.06Å, a 7,000 Å SiO ₂ single layer film is recommended, and for a 1.3 Å laser wavelength, 9400Å is recommended. As a method of providing the antireflection film 6, any known means may be used, and the film thickness thereof is 2700Å
It is a degree. For the same purpose, a similar antireflection film 6'can be provided on the opposite surface side of the substrate 1.

The laser mask of the present invention can be formed by using a lift-off method in addition to the method of forming a mask blank by etching (ordinary patterning) as described above.

[Examples] Next, specific examples of the present invention will be described, but the present invention is not limited to these embodiments.

A mask blank was prepared by forming a three-layered reflective film of chromium 700Å, copper-aluminum alloy 2500Å and 400Å and a 2000Å silicon dioxide film on a cleaned quartz glass substrate. The thin film was formed by magnetron sputtering. The three layers of the metal film of the reflective film are continuously sputtered, and no foreign matter is mixed in during the process.
Has a reflectance of 95% or more for 06 μm and 100 kg / cm
It had an adhesive force of ² or more.

Since this mask blank has a high viscosity, a thick film can be formed at one time by applying AZ-5214E (Positive photosensitive resin manufactured by Hoechst Co., Ltd.) to a resist layer by spinner coating to a thickness of 1.7 μm that produces dry etching resistance. The letter pattern was exposed. After that, the resist layer in the exposed portion was removed by using the designated developing solution of AZ-5214E to form a resist pattern.

Next, the mask blank on which this resist pattern was formed was set in a reactive ion etching apparatus, and dry etching was performed by the following procedure to obtain a laser mask.

Exhaust gas → O ₂ gas introduction → Plasma discum treatment with O ₂ gas → Exhaust gas → C ₂ F ₆ gas introduction → Silicon dioxide film dry etching → Exhaust gas → Cu, Cu-Al wet etching → Cr wet etching Note that Cu and Cu- Al wet etching is performed by immersing in a chromium oxide aqueous solution diluted to a ratio of 125 g / l for 1 to 3 minutes at room temperature. The wet etching of Cr is performed by dipping it in a diluted permanganate aqueous solution at a ratio of 62.5 g / l for 5 minutes at 30 ° C. to 35 ° C.

The etching of the silicon dioxide film C ₂ F ₆ gas with a total pressure of 0.01 torr, carried out at discharge power density of 0.3 w / cm ^2, the etching of the reflective film is total pressure 0.1 torr, the discharge power density 0.2 w / cm ² I did.

When the marking was carried out using the obtained laser mask, there were no distorted characters as in the past, and clear characters could be marked.

[Effects of the Invention] As described in detail above, when marking is performed using the laser mask of the present invention, a bridge is not required in the image part (character part) like a conventional metal plate and distorted characters are generated. You can use it to cleanly mark characters. Further, the three-layer structure of the metal film is used as the reflective film, so that the adhesive force to the glass substrate is improved. That is, in the present invention, the chromium film having good adhesion to the glass substrate serves as an adhesive, and the adhesion tends to be insufficient between the simple substance of copper and the chromium film, and a copper alloy film is provided between them. I put it in,
As a result, a copper alloy film is cooperatively deposited on the glass substrate. Next, since the copper film has good conductivity, it is possible to prevent static electricity from charging the reflective film and prevent foreign matter such as dust from adhering to the reflective film and pattern loss due to electrostatic breakdown. Further, by stacking the copper wire and the copper alloy film, it is possible to prevent the generation of pinholes during the film formation that occurs when the copper single layer is formed, and it is also possible to improve the light shielding property as the laser mask. In addition, since the reflective film has a three-layer structure, the thickness of the reflective film can be reduced, and as a result, corrosion resistance and etching shape (prevention of chipping) can be improved.
Furthermore, a silicon dioxide film can be provided on the reflective film to prevent discoloration of the reflective film, and if the processes up to this point are completed, it can be mass produced and stored as a blank. Quick delivery is possible and quality is stable. Further, by providing an antireflection film on the surface of the mask on the reflection film side, it is possible to prevent reflection of laser light on the substrate of the image portion (light transmitting portion) and protect the edge portion of the image.

[Brief description of drawings]

FIG. 1 is a sectional view showing the structure of a mask blank used for manufacturing the laser mask of the present invention, and FIG. 2 (a).
(D) is sectional drawing which shows an example of the manufacturing method of the laser mask of this invention in order of process, FIG. 3 is sectional drawing of the metal plate which shows a prior art example, FIG. 4 is a figure which shows an example of the marking character by a prior art. Is. 1 ... Quartz glass substrate 2 ... Reflective film 2a ... Chromium film 2b ... Copper alloy film 2c ... Copper film 3 ... Silicon dioxide film 4 ... Resist pattern 5 ... Laser light 6 ... Anti-reflection film 7 …… Metal plate 8 …… Bridge

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A 1-243062 (JP, A) JP-A 1-214859 (JP, A) JP-A-60-250345 (JP, A)

Claims (2)

[Claims] 1. A patterned reflective film having a three-layer structure in which a chromium film, a copper alloy film and a copper film are laminated in this order on a quartz glass substrate, and a patterned silicon dioxide film also provided thereon. Laser mask characterized by becoming. 2. The laser mask according to claim 1, wherein an antireflection film is provided on the surface of the mask and the surface on the reflection film side.