Metal line structure of optical scanner and method of fabricating the same

A metal line structure of an optical scanner and a method of fabricating the same are provided. The metal line structure of the optical scanner includes: a glass substrate having a metal line region etched to a predetermined depth; a metal line formed in the metal line region; a diffusion barrier layer that is formed on the glass substrate and covers the metal line; and an optical scanner structure combined with the glass substrate.

CROSS-REFERENCE TO RELATED PATENT APPLICATIONS

This application claims the benefit of Korean Patent Application No. 10-2005-0030747, filed on Apr. 13, 2005, in the Korean Intellectual Property Office, the disclosure of which is being incorporated herein in its entirety by reference.

BACKGROUND OF THE DISCLOSURE

1. Field of the Disclosure

The present disclosure relates to a metal line structure of an optical scanner and a method of fabricating the same.

2. Description of the Related Art

Micro actuators having a micro electro mechanical system (MEMS) structure which uses an electrostatic effect caused by a comb type electrode are used to form an optical scanner that scans a laser beam in a projection TV.

FIG. 1is a perspective view of a microscanner100having a double comb structure that is disclosed in Korean Patent Application No. 2004-0059114, andFIG. 2is a cross-sectional view of the microscanner100illustrated inFIG. 1.

Referring toFIGS. 1 and 2, the microscanner100includes a stage12having a mirror surface12athereon, upper and lower substrates20and10respectively spaced apart from upper and lower portions of the stage12, and a supporting portion which supports the sides of the stage12so that the stage12can be suspended between the upper and lower substrates20and10. A plurality of driving comb electrodes14aand14bare provided so as to be perpendicular to each other while being spaced apart from each other by a predetermined distance at the sides of the stage12. A plurality of upper fixed comb electrodes21aand21band a plurality of lower fixed comb electrodes11aand11bare disposed on the upper substrate20and the lower substrate10, respectively, so that they are alternately formed in a zigzag pattern with the driving comb electrodes14aand14b.

The supporting portion includes a rectangular fixed frame16and a torsion spring13. The fixed frame16is formed on the lower substrate10to surround the stage12, and the torsion spring13connects the fixed frame16and the stage12.

A fixed frame26corresponding to the fixed frame16is connected to a lower surface of the upper substrate20. The fixed frames16and26are connected to each other by an adhesive layer28interposed therebetween. The fixed frames16and26include conductive layers16a,16c,26a, and26cand insulating layers16band26bformed between the conductive layers16a,16c,26a, and26c, respectively.

The conductive layer16atransmits voltages applied to a metal line and electrode pads18aand18bdisposed on the lower substrate10to lower fixed comb electrodes11aand11b, respectively. An electrode pad19is disposed above the conductive layer16c. A voltage applied to the electrode pad19is transmitted to the driving comb electrodes14aand14bvia the conductive layer16band the torsion spring13.

An opening25may be formed in the upper substrate20corresponding to the stage12so that the stage12can be exposed to the outside. Through holes22aand22bare formed at left and right sides of the opening25of the upper substrate20, and electrode pads24aand24bare formed on the top surface of the upper substrate20passing the through holes22aand22b.

The electrode pads24aand24bare connected to the fixed frame26aformed on the upper substrate20. Thus, the voltages applied to the electrode pads24aand24bare transmitted to the fixed comb electrodes21aand21b, respectively, via the fixed frame26a.

FIGS. 3A through 3Eare cross-sectional views for explaining a method of fabricating a lower structure of an optical scanner ofFIGS. 1 and 2.

Referring toFIG. 3A, Pyrex glass10is etched to form a metal line region having a predetermined depth. Subsequently, a Cr layer and an Au layer are sequentially deposited to a thickness of 300/4000 Å and are patterned, thereby forming metal lines18aand18b.

Referring toFIG. 3B, a silicon on insulator (SOI) substrate having an SiO2insulating layer16bformed to a thickness of 1-2 μm between a first silicon layer16aand a second silicon layer16cis prepared. The insulating layer16bis used as an etch stop. The first silicon layer16ais etched, thereby forming a portion of a rectangular fixed frame16and fixed comb electrodes11aand11b.

Referring toFIG. 3C, the etched first silicon layer16ais anodic bonded on the glass substrate10ofFIG. 3A. In this case, the glass substrate10is maintained at a pressure of 800 N at 380° C. and in a vacuum atmosphere of 0.05 Torr for 4 minutes.

Referring toFIG. 3D, a mask (not shown) is formed on the second silicon layer16cat a region for a stage12, driving comb electrodes14aand14b, and a torsion spring13and then, a portion that is not covered by the mask is etched using inductively coupled plasma reactive ion etching (ICPRIE), so that the insulating layer16bis exposed via an exposed region of the mask.

Referring toFIG. 3E, the exposed insulating layer16bis removed by performing wet etching using a sulfuric acid solution and a BOE solution. Subsequently, a mirror surface12ahaving 99% or more reflectivity is formed on a top surface of the stage12so as to minimize damage caused by a laser beam for an optical scanner.

In the metal lines18aand18b, hillocks are generated when Au is dispersed into the first silicon layer16aduring the anodic bonding, and further, the metal lines18aand18bmay be broken.FIG. 4is a photo showing hillocks generated during the anodic bonding. In addition, during a process of removing the insulating layer16billustrated inFIG. 3E, Au may be deposited by chemical reaction.

SUMMARY OF THE DISCLOSURE

The present invention may provide a metal line structure of an optical scanner in which a metal line is not exposed during anodic bonding and chemical etching.

The present invention also may provide a method of fabricating a metal line structure of an optical scanner by which a metal line is prevented from being broken during anodic bonding and chemical etching.

According to an aspect of the present invention, there may be provided a metal line structure of an optical scanner, the metal line structure of the optical scanner including: a glass substrate having a metal line region etched to a predetermined depth; a metal line formed in the metal line region; a diffusion barrier layer that is formed on the glass substrate and covers the metal line; and an optical scanner structure combined with the glass substrate.

A lower portion of the optical scanner structure may be formed of silicon and the optical scanner structure may be anodic bonded to the glass substrate.

The diffusion barrier layer may be formed of a material selected from the group consisting of TiN, TaN, Ti, Pt, TiW, and Ni.

The diffusion barrier layer may be formed to a thickness of 500-2000 Å.

According to another aspect of the present invention, there is provided a method of fabricating a metal line structure of an optical scanner, the method including: patterning a metal line region on a glass substrate to a predetermined depth; forming a metal line in the metal line region; forming a diffusion barrier layer that covers the metal line, on the glass substrate; and anodic bonding an optical scanner structure having a lower portion formed of silicon to the glass substrate.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

FIG. 5is a cross-sectional view of an optical scanner200according to an embodiment of the present invention. Like reference numerals inFIGS. 1 and 2and5denote like elements, and a detailed description thereof is being omitted.

Referring toFIG. 5, partial regions of the glass substrate10are etched to a predetermined depth, for example, 5000 Å, and a metal line110is formed in the etched regions. The metal line110may be formed of a Cr/Au layer to a thickness of 300/4000 Å.

In addition, a diffusion barrier layer112that covers the metal line110is formed on the glass substrate10. The diffusion barrier layer112may be formed to a thickness of about 500-2000 Å. The diffusion barrier layer112is formed of a material used to prevent Au of the metal line110from being diffused into a silicon layer during anodic bonding and to prevent the metal line110from being broken during chemical etching. The diffusion barrier layer112may be a conductive layer formed of a material, such as, TiN, TaN, Ti, Pt, TiW, and Ti. The material used to form the diffusion barrier layer112protects an Au layer of the metal lines110during chemical etching and is stable even at an anodic bonding temperature.

The diffusion barrier layers112are connected to an external electrode pad, so as to apply power to a silicon layer16aand fixed comb electrodes11aand11b.

When the silicon layer16ais anodic bonded to the glass substrate10, Au formed below the diffusion barrier layer112is prevented from being diffused into the silicon layer16a. Thus, the metal line110is prevented from being broken. In addition, since a major portion of the diffusion barrier layer112is protected during a process of removing the insulating layer16bwhich is a chemical etching process, the metal line110is prevented from being broken.

FIGS. 6A through 6Fare schematic cross-sectional views for showing a method of fabricating a lower structure of an optical scanner ofFIG. 5, according to an embodiment of the present invention.

Referring toFIG. 6A, Pyrex glass10is etched to form a metal line region having a predetermined depth, for example, 5000 Å. Subsequently, a Cr layer and an Au layer are sequentially deposited to a thickness of 300/4000 Å on the glass10and then are patterned, thereby forming metal lines110.

Referring toFIG. 6B, a metal layer having a thickness of about 500-2000 Å, for example, a metal layer formed of a material selected from TiN, TaN, Ti, Pt, TiW, and Ni, is deposited on the metal line110. Subsequently, the metal layer is patterned, thereby forming a diffusion barrier layer112that covers the metal lines110.

Referring toFIG. 6C, a silicon on insulator (SOI) substrate having an SiO2 insulating layer16bis formed to a thickness of 1-2 μm between a first silicon layer16aand a second silicon layer16cis prepared. The insulating layer16bis used as an etch stop. The first silicon layer16ais etched, thereby forming a portion of a rectangular fixed frame16and fixed comb electrodes11aand11b.

Referring toFIG. 6D, the etched first silicon layer16ais anodic bonded on the glass substrate10ofFIG. 6B. In this case, the glass substrate10is maintained at a pressure of 800 N at 380° C. and in a vacuum atmosphere of 0.05 Torr for 4 minutes.

Referring toFIG. 6E, a mask (not shown) is formed on the second silicon layer16cat a region for a stage12, driving comb electrodes14aand14b, and a torsion spring13of a supporting shaft, and then, a portion that is not covered by the mask is etched using inductively coupled plasma reactive ion etching (ICPRIE), so that an insulating layer16bis exposed via an exposed region of the mask.

Referring toFIG. 6F, the exposed insulating layer16bis removed by performing wet etching using a sulfuric acid solution and a BOE solution. Subsequently, a mirror surface12ahaving 99% or more reflectivity is formed on a top surface of the stage12so as to minimize damage caused by a laser beam for an optical scanner.

In the metal structure having the diffusion barrier layer, the diffusion barrier layer112prevents Au from being diffused into the silicon layer during anodic bonding. Thus, the metal lines110are prevented from being broken caused by the hillocks. In addition, when the insulating layer16bis chemically etched, an etchant is prevented from eroding into the metal line110, and the metal lines110are prevented from being broken.

As described above, in the metal line structure of the optical scanner and the method of fabricating the same according to the present invention, the metal line is protected by the diffusion barrier layer during anodic bonding and chemical etching such that the metal line is prevented from being broken. Thus, the production yield of the optical scanner is increased, and the reliability thereof is improved.