KR19990019666A - Manufacturing method of thin film type optical path control device - Google Patents

Abstract

The present invention relates to a method for manufacturing a thin film type optical path control device, to form a sacrificial layer on the substrate, to form an adhesive layer to improve the adhesion with the photoresist layer on the sacrificial layer, and to apply a photoresist layer on the adhesive layer One end of the photoresist layer in the region where the drain pad is formed is removed by an exposure and development process, and the support layer is formed by etching the adhesive layer and the sacrificial layer along the pattern of the photoresist layer, and the remaining photoresist layer is formed. Stripping process, the adhesive layer is etched and removed as a whole, a membrane, a lower electrode, a strain layer and an upper electrode are deposited on the support and the sacrificial layer to form a cantilever-shaped actuator, and an image signal voltage is applied to the actuator. Remove the via contact and the sacrificial layer to apply the air gap A step of sex.

Therefore, the stress is not concentrated in one place even when the strained layer is contracted in the process of forming the piezoelectric material PZT or PLZT by the Sol-Gel method and then performing the rapid heat treatment process for phase change. Since it is dispersed without, it can bring about the effect of suppressing crack occurrence.

Description

Manufacturing method of thin film type optical path control device

The present invention relates to a method of manufacturing a thin film type optical path control device, and more particularly, to adjust the thin film type optical path for preventing the crack of the deformation layer by smoothing the edges of the support when the sacrificial layer pattern for forming the support of the actuator. A method of manufacturing a device.

In general, an optical path control device capable of forming an image by adjusting a light flux is a direct view type image display device such as a CRT (Cathod Ray Tube) or a projection type image display device according to a method of projecting a light beam incident from a light source on a screen. Liquid crystal displays (hereinafter referred to as "LCD"), DMD (Deformable Mirror Device), AMA (Actuated Mirror Arrays) and the like.

Although CRT devices have excellent image quality, as the screen size increases, the weight and volume of the device increase, and the manufacturing cost thereof increases. In contrast, a liquid crystal display (LCD) can be formed into a flat plate, but the incident light flux Due to the polarization of the light having a low light efficiency of 1 to 2%, there was a problem that the response speed of the liquid crystal material therein is slow.

Accordingly, in order to solve the problems of the LCD as described above, a device such as a DMD or an AMA has been developed. Currently, AMA can achieve a light efficiency of 10% or more, while DMD has a light efficiency of about 5%. In addition, the AMA is not only affected by the polarity of the incident luminous flux but also does not affect the polarity of the luminous flux.

Typically, the respective actuators formed inside the AMA cause deformation depending on the electric field generated by the applied image signal and bias voltage. When this actuator causes deformation, each of the mirrors mounted on top of the actuator is inclined in proportion to the magnitude of the electric field.

Thus, these inclined mirrors can reflect light incident from the light source at a predetermined angle. Piezoelectric ceramics such as PZT (Pb (Zr, Ti) O ₃ ), or PLZT ((Pb, La) (Zr, Ti) O ₃ ) are used as a constituent material of the actuator for driving the respective mirrors. As the constituent material of this actuator, electrodistorted ceramics such as PMN (Pb (Mg, Nb) O ₃ ) can be used.

The AMA is classified into a bulk type and a thin film type. Currently, AMA is the main trend of the thin-film optical path control device. The thin film type optical path control device is filed under the name of the manufacturing method of the thin film type optical path control device which the applicant has filed a patent application with the Korean Patent Office.

FIG. 1 is a plan view of a thin film type optical path adjusting device described in the prior application, and FIG. 2 is a cross-sectional view taken along line AA ′ of FIG. 1.

1 and 2, the thin film type optical path adjusting device described by the prior application includes a substrate 5 and an actuator 65 formed thereon.

The actuator 65 has a cantilever shape in which one side is supported at a portion where the drain pad 10 is formed below, and includes a membrane 30, a lower electrode 35, a strained layer 40, and an upper electrode 45. And a via contact 55 vertically formed up to the drain pad 10 so that the drain pad 10 and the lower electrode 35 are electrically connected to each other. The bottom surface of the actuator 65 may increase adhesive force during the manufacturing process. The adhesive layer 27 for this remains.

One side of the planar shape of the actuator 65 has a rectangular concave portion at the center thereof, and the concave portion is formed in a shape widening stepwise toward both edges. The other side of the actuator 65 has a quadrangular protrusion that narrows in a stepped manner toward the central portion corresponding to the concave portion. Therefore, the concave portion of the actuator 65 adjacent to the concave portion of the actuator 65 is fitted, and the rectangular projection is fitted to the concave portion of the adjacent actuator 65.

3A through 3D are manufacturing process diagrams illustrating a sacrificial layer pattern process in the manufacturing process of the above-described thin film type optical path adjusting device, and the sacrificial layer 25 is formed on the substrate 5. The sacrificial layer 25 is formed of a silicate glass (PSG) to have a thickness of about 0.5 to 4.0㎛ by the atmospheric pressure chemical vapor deposition (APCVD) method. At this time, since the sacrificial layer 25 covers the upper portion of the substrate 5 in which the transistor is embedded, the surface flatness is very poor. Therefore, the surface of the sacrificial layer 25 is planarized by using a spin on glass (SOG) method or a chemical mechanical polishing (CMP) method.

Subsequently, a silicon oxide (SiO ₂ ) adhesive layer 27 is deposited to increase adhesion to the photoresist layer 26 when the sacrificial layer 25 is etched to form the support part pattern of the actuator 65, and then the photoresist layer. (26) is applied.

Next, the photoresist layer 26 corresponding to the portion where the drain pad 10 is formed is removed through an exposure and development process.

Subsequently, the exposed adhesive layer 27 and the sacrificial layer 25 are etched to form the support part 70, and then the membrane 30, the lower electrode 35, the strained layer 40, and the upper electrode 45 are formed. .

However, in the adhesive layer 27 and the sacrificial layer 25 pattern process for forming the support part 70 of the actuator 65 according to the conventional manufacturing method of the thin film type optical path control device, the silicon oxide layer of the adhesive layer is formed of the PSG layer of the sacrificial layer. It proceeds slower than the etch rate, the edge of the patterned adhesive layer 27 is developed in a corner shape, the membrane 30, the lower electrode 35, deposited on such a support 70 pattern shape, The strained layer 40 and the upper electrode 45 have a shape that is sharply bent at the edge of the adhesive layer 27, there is a fear that stress is concentrated on the edge portion during the manufacturing process.

In particular, the deformable layer 40 is formed of a piezoelectric material PZT or PLZT to have a thickness of 0.1 ~ 1.0㎛ by the sol-gel method (Rapid Thermal) at a temperature of about 650 ℃ for phase transition In the process of performing annealing (RTA), there was a problem that cracks were generated at the edges where stress on deformation was concentrated.

Moreover, such cracks in the deformable layer 40 may provide a path that may cause a short between the upper electrode 45 and the lower electrode 35.

The present invention is to solve the conventional problems as described above, by patterning the support portion in the adhesive layer and the sacrificial layer to remove the adhesive layer as a whole to prevent the edges of the patterned support portion to protrude, which can suppress cracking of the deformation layer Its purpose is to provide a method for manufacturing a thin film type optical path control device.

In order to achieve the above object, the present invention provides a sacrificial layer on a substrate having M × N (M, N is an integer) transistors and a drain pad formed on one side thereof, and a photoresist layer on the sacrificial layer. In order to improve the adhesion of the adhesive layer is formed, a photoresist layer is applied on the adhesive layer, one end of the photoresist layer on the portion where the drain pad is formed by removing and developing the process, and along the pattern of the photoresist layer The adhesive layer and the sacrificial layer are etched to form a support, the remaining photoresist layer is removed by a stripping process, the adhesive layer is etched and removed entirely, and a membrane, a lower electrode, a strained layer, and an upper portion are formed on the support and the sacrificial layer. The electrode is deposited to form a cantilever-shaped actuator, and an image signal voltage is applied to the actuator. Providing a via contact, and method of manufacturing the thin-film optical path control device comprising the steps of forming a cliff eogaep by removing the sacrificial layer for applying.

The above objects and various advantages of the present invention will become more apparent from the preferred embodiments of the invention described below with reference to the accompanying drawings by those skilled in the art.

1 is a plan view of a thin film type optical path control device according to the applicant's prior application,

2 is a cross-sectional view taken along the line A-A 'of FIG.

3a to 3d is a manufacturing process diagram showing a conventional sacrificial layer pattern process,

4 is a cross-sectional view showing a thin film type optical path control apparatus according to the present invention;

5a to 5g is a manufacturing process diagram of a thin film type optical path control apparatus according to the present invention.

* Explanation of symbols for main parts of the drawings

100: substrate 105: drain pad

110: protective layer 115: etch stop layer

120 sacrificial layer 121: photoresist layer

122: Adhesion 130: Membrane

135: lower electrode 140: deformation layer

145: upper electrode 150: via hole

155: Via contact 160: Actuator

165: support portion 170: drive portion

Hereinafter, a thin film type optical path adjusting apparatus according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

As shown in FIG. 4, the optical path control apparatus according to the present invention includes a substrate 100 and an actuator 160 formed on the substrate 100. The substrate 100 is disposed on the drain pad 105 formed on one side of the substrate 100, the protective layer 110 and the protective layer 110 stacked on the substrate 100 and the drain pad 105. The stacked etch stop layer 115 is included.

The actuator 160 includes a membrane 130, a lower electrode 135, and a strained layer on a substrate 100 having M × N (M, N is an integer) transistors and a drain pad 105 formed on one side thereof. And a via contact 155 electrically connecting the upper electrode 145 and the drain pad 105 to apply an image signal voltage to the actuator 160. The support 165 of the actuator 160 and the refracted portion of the driving unit 170 are rounded to be curved.

Hereinafter, the manufacturing method of the thin film type optical path control device according to the present invention will be described in detail.

5A to 5G show a manufacturing process diagram of a thin film type optical path control apparatus according to a preferred embodiment of the present invention.

Referring to FIG. 5A, a protective layer 110 of silicate glass (PSG) material is formed on an upper portion of a substrate 100 having M × N transistors embedded in a matrix and having a drain pad 105 formed on one side thereof. To form. The protective layer 110 is formed to have a thickness of about 1.0 to 2.0 μm using a chemical vapor deposition (CVD) method. The protective layer 110 prevents damage to the substrate 100 in which the transistor is embedded during subsequent processing.

An etch stop layer 115 made of nitride is formed on the passivation layer 110. The etch stop layer 115 is formed to have a thickness of about 1000 to 2000 kPa using a low pressure chemical vapor deposition (LPCVD) method. The etch stop layer 115 prevents the substrate 100 and the protective layer 110 from being damaged by the subsequent etching process.

The sacrificial layer 120 is formed on the etch stop layer 115. The sacrificial layer 120 is formed of a silicate glass (PSG) to have a thickness of about 0.5 to 4.0㎛ by the atmospheric pressure chemical vapor deposition (APCVD) method. In this case, since the sacrificial layer 120 covers the upper portion of the substrate 100 in which the transistor is embedded, the flatness of the surface thereof is very poor. Therefore, the surface of the sacrificial layer 120 is planarized by using a spin on glass (SOG) method or a chemical mechanical polishing (CMP) method.

Referring to FIG. 5B, a silicon oxide (SiO ₂ ) adhesive layer 122 is deposited on the sacrificial layer 120, and then the photoresist layer 121 is coated on the sacrificial layer 120.

Referring to FIG. 5C, the photoresist layer 121 corresponding to the portion where the drain pad 105 is formed is patterned through an exposure and development process.

Referring to FIG. 5D, the adhesive layer 122 and the sacrificial layer 120 are etched along the pattern of the photoresist layer 121 to expose a portion of the etch stop layer 115 to form the support part 165. The remaining photoresist layer 121 is removed through a stripping process. At this time, the silicon oxide layer of the adhesive layer 122 progresses slower than the etch rate of the PSG layer of the sacrificial layer 120, so that the edge of the patterned adhesive layer 122 protrudes. Therefore, as shown in FIG. 5E, the remaining adhesive layer 122 is entirely removed through the etching process. In this process, the edge of the sacrificial layer 120 patterned with the support 165 is rounded more smoothly.

Referring to FIG. 5F, the membrane 130 is formed on the exposed etch stop layer 115 and on the sacrificial layer 120. The membrane 130 is formed to have a thickness of about 0.1 to 1.0 ㎛ using a low pressure image vapor deposition (LPCVD) method. At this time, the stress in the membrane 130 is adjusted while changing the ratio of the reaction gas in the low pressure reaction vessel. A lower electrode 135 made of a metal such as platinum, platinum-tantalum, or the like having excellent electrical conductivity is formed on the membrane 130 to a thickness of about 500 to 2000 micrometers by a sputtering method. The lower electrode 135 receives an image signal from the transistor embedded in the driving substrate 100 via the drain pad 105 and the via hole 150 as a signal electrode.

Subsequently, the strained layer 140 made of a piezoelectric material such as PZT or PZLT is disposed on the lower electrode 135 using a sol-gel method, a sputtering method, or a chemical vapor deposition (CVD) method. It is formed to have a thickness of about -1.0 μm. In addition, the strained layer 140 is phase-shifted using a rapid heat treatment (RTA) method. On the other hand, the connection part of the support part 165 of the actuator 160 and the drive part 170 which are the most vulnerable to crack generation by stress concentration during the rapid heat treatment process of the deformation layer 140 can be rounded gently to disperse the deformation stress to some extent. Cracking is suppressed as much as possible.

The upper electrode 145 made of aluminum, platinum or silver is formed on the strained layer 140 to have a thickness of about 0.1 μm to about 1.0 μm by the sputtering method.

The upper electrode 145 is applied with a bias voltage as a common electrode to generate an electric field between the lower electrode 135 and the upper electrode 145.

Referring to FIG. 5G, the strained layer 140, the lower electrode 135, the membrane 130, the etch stop layer 115, and the protective layer 110 are formed from a portion of the strained layer 140 in which the drain pad 105 is formed. After etching sequentially to form the via hole 150, the drain pad 105 and the lower electrode 135 is electrically connected to the inside of the via hole 150 by sputtering a metal such as tungsten, platinum, aluminum, or titanium. The via contact 155 is formed to be connected to each other. The via contact 155 is formed vertically from the lower electrode 135 to the top of the drain pad 105 in the via hole 150. Accordingly, the image signal is applied to the lower electrode 135 through the drain pad 105 and the via contact 155 from the transistor embedded in the substrate 100.

Subsequently, the strained layer 140, the lower electrode 135, and the membrane 130 are sequentially patterned, and then the sacrificial layer 120 is removed with hydrofluoric acid to form an air gap.

As described above, after completing the device of the thin film type AMA, platinum-tantalum (Pt-Ta) is deposited on the lower end of the driving substrate 100 using a sputtering method to form an ohmic contact (not shown).

Next, after applying a photoresist (not shown) on the driving substrate 100, a tape carrier package for applying a bias voltage to the upper electrode 145 and an image signal to the lower electrode 135. (Not shown) The driving substrate 100 is cut to have a predetermined thickness in preparation for bonding.

Subsequently, the pad portion of the AMA panel is etched using a dry etching method to expose the pad (not shown) of the AMA panel required for TCP bonding.

As described above, the driving substrate 100 on which the thin film type AMA element is formed is completely cut into a predetermined shape, and then the pad of the AMA panel and the TCP are connected to complete the manufacture of the thin film type AMA module.

In the thin film type optical path adjusting device, an image signal voltage is applied to the lower electrode 135, which is a signal electrode, and a bias voltage is applied to the upper electrode 145, which is a common electrode, between the upper electrode 145 and the lower electrode 135. An electric field will be generated. The strained layer 140 between the upper electrode 145 and the lower electrode 135 causes deformation by the electric field, and the strained layer 140 contracts in a direction perpendicular to the electric field. Accordingly, the actuator 160 including the deformation layer 140 is bent at a predetermined angle to form an image by projecting the light beam incident from the light source onto the screen through the slit.

In the above description, it should be understood that those skilled in the art can make modifications and changes to the present invention without changing the gist of the present invention as it merely illustrates a preferred embodiment of the present invention.

Therefore, the thin film type optical path control device according to the present invention removes the adhesive layer interposed to improve the adhesion between the sacrificial layer and the photoresist layer, and in the process, the edges of the support pattern are gently rounded, and the membrane and the lower electrode deposited thereon. In addition, the strained layer and the upper electrode have a structure in which stress is dispersed by following such a shape, and in particular, a piezoelectric material, PZT or PLZT, is formed by a sol-gel method and then rapidly heat-treated for phase transition. Even if the strained layer shrinks during the process, stress may be dispersed without being concentrated in one place, which may have an effect of suppressing cracking.

Claims (1)

Forming a sacrificial layer on a substrate having M × N (M, N is an integer) and having a drain pad formed on one side thereof, and forming an adhesive layer to improve adhesion to the photoresist layer on the sacrificial layer. And applying a photoresist layer on the adhesive layer, removing one end of the photoresist layer in the region where the drain pad is formed by exposure and development, and etching the adhesive layer and the sacrificial layer along the pattern of the photoresist layer. Forming a support, removing the remaining photoresist layer by a stripping process, etching and removing the adhesive layer as a whole, and depositing a membrane, a lower electrode, a strained layer, and an upper electrode on the etched sacrificial layer. Forming a cantilever-shaped actuator and transmitting an image signal to the actuator Forming a via contact for applying the method for manufacturing a thin-film optical path control apparatus to remove the sacrificial layer and forming a cliff eogaep a.