KR100342470B1 - Fabrication method of a metal mask - Google Patents

Abstract

Method for producing a metal mask for forming the silica optical waveguide according to the present invention,

Forming a silica layer on the silicon substrate; Forming a photoresist layer on the silica layer; Patterning the photoresist layer to form a photoresist mask; Forming a metal layer on the silica layer and the photoresist mask; Wet-etching and removing the metal layer deposited on the sidewalls of the photoresist mask; And removing the photoresist mask with a photoresist removal liquid.

Description

Manufacturing method of metal mask {FABRICATION METHOD OF A METAL MASK}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a silica optical waveguide device, and more particularly, to a method for manufacturing a metal mask.

Metal masks used in the manufacturing method of the silica optical waveguide device are mainly used for etching a thick layer that is difficult to act as a mask only by photoresist. A conventional method of fabricating a metal mask may include forming a metal layer by a sputtering process, forming a photoresist layer on the metal layer, patterning the photoresist layer, and patterning the photoresist layer. Etching the metal layer using the photoresist mask. In addition, a method commonly used to etch the metal layer is a reactive ion etching (RIE) process. The metal mask fabricated by the reactive ion etching process is likely to have a non-uniform line width depending on the position on the substrate, and this non-uniformity of the line width is referred to as a bull's eye effect.

For example, it is assumed that chromium (Cr) is used as the material of the metal layer. The bullseye effect occurs in a reactive ion etching process that etches the chromium layer to form a chrome mask. For this reason, the line width difference of the said chrome mask arises according to the position in a board | substrate. Under the processing conditions of 200 W and 150 × 10 ⁻³ torr, a 0.5 μm thick chromium layer has a time difference of about 2 minutes for etching the edge and the center portion. As the thickness of the chromium layer increases, the time difference between etching the edges and the center portion increases, which increases the bullseye effect. This line width reduction will not occur if the trajectory of all cations in the plasma is in a direction perpendicular to the substrate.

However, under the process conditions of the ion reaction etching, since the DC voltage is as small as about -30 V, ions incident to the portion where the chromium mask is formed by being etched in the vertical direction in the chromium layer by the mask charging effect. Will hit the side of the chrome mask. As a result, the edge line width of the chrome mask where the bottom is first exposed is further reduced.

A lift-off process may be used to exclude the bullseye effect, and the metal mask may be easily manufactured without performing a dry etching process. A disadvantage of the lift-off process is that when the metal mask is fabricated to etch the silica optical waveguide, the sidewall roughness of the silica optical waveguide becomes large to increase the loss of the optical signal traveling to the silica optical waveguide. In addition, there is a problem that the lift-off of the metal layer is not good when the distance between the silica optical waveguides to be manufactured is narrow.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional problems, and an object of the present invention is to provide a method of manufacturing a metal mask capable of improving the sidewall roughness of the metal mask and allowing patterning at a narrow interval.

In order to achieve the above object, a method of manufacturing a metal mask for forming a silica optical waveguide according to the present invention,

Forming a silica layer on the silicon substrate;

Forming a photoresist layer on the silica layer;

Patterning the photoresist layer to form a photoresist mask;

Forming a metal layer on the silica layer and the photoresist mask;

Wet-etching and removing the metal layer deposited on the sidewalls of the photoresist mask;

And removing the photoresist mask with a photoresist removal liquid.

1A to 3 are views showing a method of manufacturing a metal mask according to a preferred embodiment of the present invention.

Hereinafter, with reference to the accompanying drawings will be described an embodiment of the present invention; In describing the present invention, detailed descriptions of related well-known functions or configurations are omitted in order not to obscure the subject matter of the present invention.

1A to 3 are views illustrating a method of manufacturing a metal mask according to a preferred embodiment of the present invention.

FIG. 1A illustrates a process of forming a clad layer 12 and a core layer 13 on a silicon substrate 11 through a flame hydrolysis deposition (FHD) process and a sintering process. Indicates. Processes for forming the clad layer 12 and the core layer 13 on the silicon substrate 11 include chemical vapor deposition (CVD), flame hydrolysis deposition, etc. Plasma Enhanced Chemical Vapor Deposition (PECVD), Low Pressure Chemical Vapor Deposition (LPCVD), and the like. Among these various processes, the flame hydrolysis deposition process is a commonly used process.

FIG. 1B illustrates a process of forming a photoresist layer on the core layer 13 and patterning the photoresist layer to form a photoresist mask 14. In the method of forming the photoresist layer, a liquid photoresist is dropped on the core layer 13, and then the silicon substrate 11 is rotated at a high speed, so that the photoresist layer is fixed on the core layer 13. A photoresist layer of thickness is formed. This method of forming a photoresist layer is called spin coating. At this time, the thickness of the photoresist layer should be larger than the thickness of the metal mask to be formed later. The photoresist mask 14 is formed through a photolithography process and an etching process.

FIG. 2A illustrates a process of forming the metal layer 15 on the photoresist mask 14 and the core layer 13 by a sputtering process. The sputtering process is easy to form a layer of a compound, an insulator material as well as a metal, and has a high energy because it has a high energy. In addition, the step coverage is good to form a uniform layer. The low layer formation rate, which is a disadvantage of the sputtering process, can be solved by using a magnetron or electron cyclotron resonance (ECR).

2B illustrates a process of wet etching the metal layer 15 stacked on the sidewall of the photoresist mask 14. The wet etching is used in a non-fine patterning process by etching with a chemical solution, and the mainly used chemical solution is H ₂ SO ₄ , H ₃ PO ₄ , H ₂ O ₂ , HF, HCL, NH ₄ OH, and the like. have. By the wet etching, the metal mask 17 is formed on the core layer, and the metal layer 16 to be removed later remains on the photoresist mask 14.

3 shows a process of removing the photoresist mask 14 using a photoresist removal liquid. At this time, the metal layer 16 stacked on the photoresist mask 14 is also removed. Accordingly, only the metal mask 17 remains on the core layer 13. Acetone may be used as the photoresist removing liquid.

As described above, in the method of manufacturing the metal mask according to the present invention, the metal layer laminated on the sidewall of the photoresist mask is previously removed by wet etching. Thereafter, the metal layer stacked on the photoresist is also removed while the photoresist mask is removed. Accordingly, the sidewall of the metal mask has a small roughness, and a uniform pattern can be obtained even at a narrow line width of 1 μm or less. In addition, it is possible to eliminate the bullseye effect and contamination problems that occur during the dry etching of the metal.

As described above, the manufacturing method of the metal mask according to the present invention has the advantage that it is possible to eliminate the bullseye effect and contamination problems by using a lift-off process.

Furthermore, the method of manufacturing the metal mask according to the present invention has the advantage that the sidewall roughness of the metal mask can be improved by wet etching of the metal layer deposited on the sidewall of the photoresist mask in advance, and the patterning of the narrow gap can be performed.

Claims (4)

In the manufacturing method of a metal mask for formation of a silica optical waveguide, Forming a silica layer on the silicon substrate; Forming a photoresist layer on the silica layer; Patterning the photoresist layer to form a photoresist mask; Forming a metal layer on the silica layer and the photoresist mask; Wet-etching and removing the metal layer deposited on the sidewalls of the photoresist mask; And removing the photoresist mask with a photoresist removal liquid. The method of claim 1, The silica layer is a method of manufacturing a metal mask, characterized in that formed by a flame hydrolysis deposition process. The method of claim 1, The photoresist layer is a metal mask manufacturing method, characterized in that formed by a spin coating process. The method of claim 1, The metal layer is a method of manufacturing a metal mask, characterized in that formed by a sputtering process.