KR19980057864A - Manufacturing method of thin film type optical path control device - Google Patents

Abstract

A method of manufacturing a thin film type optical path control apparatus capable of accurately forming a via hole is disclosed. The method includes providing an active matrix having M × N (M, N is an integer) transistors and a drain pad formed on one side thereof, wherein a membrane, a lower electrode, a strain layer, and an upper electrode are disposed on the active matrix. Forming an actuator comprising, patterning the upper electrode, the strain layer and the lower electrode, applying a photoresist on top of the patterned upper electrode, strain layer and the lower electrode, and then ultraviolet rays to the port resist Irradiating a light source and forming a via contact connecting the drain pad and the lower electrode to one side of the actuator. According to the above method, by exposing the surface of the photoresist to ultraviolet light, the surface portion of the port resist changes to hydrophilicity, so that the adhesion with the thin film, in particular the nitride membrane, is excellent, thereby accurately forming the via hole and the via contact. have. Therefore, when the sacrificial layer is etched using hydrogen fluoride, a portion of the protective layer is etched together to prevent undercuts from occurring in the via holes.

Description

Manufacturing method of thin film type optical path control device

The present invention relates to a patterning method of an Actuated Mirror Array (AMA), which is a thin film type optical path control device. More specifically, when forming a via hole in an actuator, an via treatment is performed on the photoresist to accurately form the via hole. The manufacturing method of the thin film type optical path control apparatus which can be performed.

In general, an optical path adjusting device capable of forming an image by adjusting a light beam is classified into two types. One type is a direct view type image display device, such as a CRT (Cathode Ray Tube), and the other type is a projection type image display device, a Liquid Crystal Display (LCD), or a DMD (Deformable Mirror Device), AMA, etc. This corresponds to this. Although the CRT device has excellent image quality, the weight and volume of the device increases as the screen is enlarged, and the manufacturing cost thereof increases. In contrast, a liquid crystal display (LCD) has an advantage in that its optical structure is simple and can be formed thin, thereby reducing its weight and volume. However, the liquid crystal display (LCD) has a problem that the efficiency is lowered to have an optical efficiency of 1 to 2% due to the polarization of the incident light beam, and the response speed of the liquid crystal material is slow and the inside is easily overheated.

Accordingly, in order to solve the above problems, an image display device such as a digital mirror device (DMD) or an AMA has been developed. Currently, AMA devices can achieve 10% or more light efficiency, while DMD devices have about 5% light efficiency. In addition, the AMA device improves contrast, resulting in brighter and clearer images, and is not affected by the polarity of the incident luminous flux and does not affect the polarity of the luminous flux. A schematic diagram of the engine system of AMA disclosed in this US Patent No. 5,126,836 (issued to Gregory Um) is shown in FIG. _{3 3 3 The light} path control device is disclosed in US Pat. No. 5,085,497 (issued to Gregory Um et al.). The bulk optical path control device cuts a thin layer of multilayer ceramic, mounts a ceramic wafer having a metal electrode therein on an active matrix in which a transistor is built, and then processes it by sawing. This is done by installing a mirror. However, the bulk optical path control device has a problem in that high precision is required in design and manufacturing and the response speed of the deformation part is slow. Accordingly, a thin film type optical path control apparatus that can be manufactured using a semiconductor process has been developed.

2 and 3, the thin film type optical path control device includes M × N (M, N is an integer) metal oxide semiconductor (MOS) transistors (not shown) and a drain 49 on one side. Is formed on the active matrix 41 and the actuator (43) formed on the active matrix (41).

The active matrix 41 includes a passivation layer 51 stacked on the active matrix 41 and the drain 49 and an etch stop layer 53 stacked on the passivation layer 51. ).

One side of the actuator 43 is in contact with a portion in which the drain 49 is formed in the lower portion of the etch stop layer 53, and the other side thereof is parallel to the etch stop layer 53 through an air gap 55. The membrane 57 having a stacked cross section, the lower electrode 61 stacked on the membrane 57, the deformation part 63 stacked on the lower electrode 61, and the upper part of the deformation part 63. Via holes vertically formed from the other side of the upper electrode 65 and the deformable part 63 to the drain 49 through the lower electrode 61, the membrane 57, the etch stop layer 53, and the protective layer 51. and a via contact 69 formed in the via hole 68 and the lower electrode 61 and the drain 49 are electrically connected to each other.

Hereinafter, the manufacturing method of the above-described thin film type optical path control apparatus will be described with reference to the drawings. The etch stop layer 53 prevents the protective layer 51, the active matrix 41, and the like from being etched during the subsequent etching process. A sacrificial layer 56 is stacked on the etch stop layer 53. The sacrificial layer 56 is formed of phosphorous silicate glass (PSG) having a high concentration of phosphorus (PG) to have a thickness of about 1.0 to 2.0 μm using an Atmospheric Pressure CVD (APCVD) method. In this case, since the sacrificial layer 56 covers the upper portion of the active matrix 41 in which the transistors are embedded, the flatness of the surface thereof is very poor. Accordingly, the surface of the sacrificial layer 56 is planarized by using a spin on glass (SG) or a chemical mechanical polishing (CMP) method. Subsequently, a photoresist (not shown) is applied on the sacrificial layer 56, and then a portion of the sacrificial layer 56 having a drain 49 formed thereon is patterned to prevent the etch stop layer 53. Part of the _{6 18 2 4 4} is applied through the drain 49 and via contact 69 from the loaded transistor. Then, Iso-Cutting is performed to separate the lower electrode 61 for each pixel.

Referring to FIG. 4D, after the upper electrode 65 is patterned into a predetermined shape, the deformable portion 63 and the lower electrode 61 are patterned in sequence. At this time, the photoresist is applied over the deformable portion 63 and the upper electrode 65 in the same manner as the patterning of the upper electrode 65, and then the deformable portion 63 is patterned into a predetermined pixel shape. The lower electrode 61 is also patterned in a predetermined pixel shape in this manner. Subsequently, the deformable portion 63, the lower electrode 6l, the membrane 57, the etch stop layer 53, and the protective layer 51 are sequentially etched from the other upper portion of the deformable portion 63 to the upper portion of the drain 49. As a result, a via hole 68 is formed from the deformable portion 63 to the drain 49. Also in this case, after the photoresist is applied on the membrane 57, the deformable portion 63, the lower electrode 61, the membrane 57, the etch stop layer 53 and the protective layer are used as a mask. The 51 is etched to form the via hole 68. Subsequently, a via contact 69 is formed such that the drain 49 and the lower electrode 61 are electrically connected to each other by a metal such as tungsten (W), platinum, or titanium (Ti). Thus, the via contact 69 is formed vertically from the lower electrode 61 to the top of the drain 49 in the via hole 68. Therefore, the image signal is applied to the lower electrode 61 through the drain 49 and the via contact 69 from the transistor embedded in the active matrix 41. After the photoresist is applied on the membrane 57, the membrane 57 is patterned into a predetermined pixel shape, and the sacrificial layer 56 is etched with hydrogen fluoride (HF) vapor to form an air gap 55. Form. After completing the thin-film AMA device as described above, by depositing a metal such as chromium (Cr), nickel (Ni), gold (Au) and the like on the bottom of the active matrix 41 using a sputtering method or evaporation method (evaporation) It forms an ohmic contact (not shown). Subsequently, after a photo resist (not shown) is coated on the active matrix 41, a bias voltage is applied to the upper electrode 65, which is a subsequent common electrode, and at the same time, the lower electrode 61, which is a signal electrode. The active matrix 41 is cut in preparation for TCP (Tape Carrier Package) bonding for applying an image signal to the tape. At this time, the active matrix 41 is cut out only to a predetermined thickness for the subsequent process. Subsequently, a photoresist is formed on top of the pads of the AMA panel to expose the pads (not shown) of the AMA panel required for TCP bonding, and then patterned using a dry etching method. After the active matrix 41 in which the thin film type AMA element is formed is completely cut into a predetermined shape, the pad of the AMA panel and the TCP are connected to complete the manufacture of the thin film type AMA module.

However, in the method of manufacturing the thin film type optical path control device, when the via contact is formed as described above, the photoresist pattern is used as an etching mask, and the sacrificial layer is removed using hydrogen fluoride (HF). A poor adhesion between the resist and the thin films (particularly the nitride membrane) causes a protective layer of insilicate glass (PSG) in the via hole to be etched from the inside together with the sacrificial layer, resulting in under cut. Therefore, a short circuit occurs in the via contact. That is, even if the chemical property of the nitride membrane to which the photoresist is applied on top is close to hydrophilic or hydrophobic thin film, the membrane is supplied by removing the photoresist during the subsequent patterning process and supplying the base hydroxide ions (OH ⁻ ). When the surface of is close to hydrophilicity, the photoresist inherent in hydrophobicity has a poor adhesiveness with the hydrophilic membrane, which causes problems such as undercut in the process of patterning with hydrophobic photoresist as a mask. It is difficult to form the via hole accurately. Due to this problem, a surfactant or the like is added to increase the wettability of the photoresist, but this method changes the properties of the photoresist depending on the addition amount of the surfactant as well as the selection of an appropriate surfactant according to the photoresist used. It is difficult to control this accurately.

Accordingly, it is an object of the present invention to provide a method of manufacturing a thin film type optical path control apparatus capable of forming a via hole in an accurate shape after forming a resist pattern having a predetermined shape on an upper portion of a thin film using a photoresist.

1 is a schematic diagram of an engine system of a conventional light path adjusting device.

In order to achieve the above object, the present invention provides a method comprising: providing an active matrix having M × N (M, N is an integer) transistors and a drain pad formed on one side thereof; Forming an actuator on the active matrix, the actuator including a membrane, a lower electrode, a strained layer, and an upper electrode; Patterning the upper electrode, the strain layer, and the lower electrode; Applying a photoresist on top of the patterned upper electrode, the deforming layer and the lower electrode, and then irradiating the photoresist with ultraviolet light; And it provides a method of manufacturing a thin film type optical path control device comprising the step of forming a via contact connecting the drain pad and the lower electrode on one side of the actuator.

FIG. 5 is a plan view of a thin film type optical path adjusting device manufactured according to the present invention, and FIG. 6 is a cross-sectional view taken along line B-B ′ of the device shown in FIG. 5.

The actuator 135 is stacked such that one side of the actuator 135 is in contact with a portion in which the drain pad 103 is formed below, and the other side thereof is parallel to the etching prevention layer 109 via the first air gap 115. Membrane 118 having a cross section, a lower electrode 12l stacked on top of the membrane 118, a strained layer 124 stacked on top of the lower electrode 121, and stacked on top of the strained layer 124. The drain pad is formed through the lower electrode 121, the membrane 118, the etch stop layer 109, and the protective layer 110 from a portion of the upper electrode 127 and the deformation layer 124 having the drain pad 103 formed thereunder. The via hole 129 vertically up to the angle 103 and the via contact 132 formed in the via hole 129 to electrically connect the lower electrode 121 and the drain pad 103 to each other.

The mirror post 143 is formed on an upper portion of the upper electrode 127, one lower portion is supported by the mirror post 143, and the other side is parallel to the upper electrode 127 via the second air gap 141. The mirror 146 is formed. The concave portion is formed in a shape that is widened stepwise toward both edges, and the other side has a quadrangular protrusion that narrows stepwise toward the center corresponding to the concave portion. Has Therefore, the concave portion of the membrane of the actuator adjacent to the concave portion of the membrane 118 is fitted, and the rectangular projection is fitted into the concave portion of the adjacent membrane.

Hereinafter, the manufacturing method of the thin film type optical path control apparatus according to the present invention will be described in detail. 7A to 7G are manufacturing process diagrams of the apparatus shown in FIG. 6. In Figs. 7A to 7F, the same reference numerals are used for the same members as Fig. 6.

Referring to FIG. 7A, silicate glass (PSG) is formed on an active matrix 100 having M × N (M and N are integers) transistors (not shown) and a drain pad 103 formed on one side thereof. The protective layer 106 which consists of these is laminated | stacked. The protective layer 106 is formed to have a thickness of about 0.1 to 1.0 μm using a chemical vapor deposition (CVD) method. The protective layer 106 protects the active matrix 100 in which the transistor is embedded during subsequent processing.

The etch stop layer 109 is formed to have a thickness of about 0.1 μm to about 1.0 μm using a low pressure chemical vapor deposition (LPCVD) method. The etch stop layer 109 prevents the protective layer 106, the active matrix 100, etc. from being etched during the subsequent etching process. The first sacrificial layer 112 is stacked on the etch stop layer 109. The first sacrificial layer 112 is formed of a phosphorus silicate glass (PSG) having a high concentration of phosphorus (PG) to have a thickness of about 0.5 to 2.0 μm using an Atmospheric Pressure CVD (APCVD) method. . In this case, since the first sacrificial layer 112 covers the upper portion of the active matrix 100 in which the transistor is embedded, the flatness of the surface thereof is very poor. Therefore, the surface of the first sacrificial layer 112 is planarized by using a spin on glass (SOG) or a CMP method.

A lower electrode 121 made of a metal such as platinum, tantalum (Ta), or platinum-tantalum (Pt-Ta) is stacked on the membrane 118. The lower electrode 121 is formed to have a thickness of about 0.1 μm to 1.0 μm using the sputtering method. An image signal is applied to the lower electrode 12l, which is a signal electrode, from the transistor embedded in the active matrix 100 through the drain pad 103 and the via contact 132 formed later.

A strained layer 124 made of PZT or PLZT is stacked on the lower electrode 121. The strained layer 124 is 0.1 to 1 using a sol-gel method, a sputtering method, or a chemical vapor deposition (CVD) method. It is formed to have a thickness of about 0 μm, preferably about 0.4 μm, and then subjected to heat treatment by a rapid heat treatment (RTA) method to perform phase shift. The strained layer l24 is deformed by an electric field generated between the upper electrode 127 which is a later formed common electrode and the lower electrode 121 which is a signal electrode. The adhesion is very poor.

Next, referring to FIG. 7D, the fifth photoresist pattern 150 is treated with ultraviolet light 160 to reduce hydrophobicity of the surface portion of the fifth port resist pattern 150 (ie, increase hydrophilicity). ). By irradiating the ultraviolet light 160 as described above, the etch resistance and adhesion of the fifth photoresist pattern 150 are increased, and residual solvent in the fifth photoresist pattern 150 is increased. Removed. In addition, due to the action of the ultraviolet light 160, the surface portion of the fifth photoresist pattern 150 made of a polymer material is partially activated to combine with oxygen molecules remaining in the remaining solvent to form the fifth photoresist pattern 150. It is thought to reduce hydrophobicity and increase hydrophilicity. Equipment for irradiating the ultraviolet light 160 on the surface of the fifth port resist pattern 150 includes an atmospheric chamber (not shown). The ultraviolet ray 160 irradiation is performed by performing the active matrix 100 at a temperature of a high temperature plate (not shown) in the chamber at a temperature of 105 ° C. to 120 ° C. for 10 seconds to 35 seconds. The temperature is raised to a temperature between 145 ° C. and 170 ° C., followed by 40 seconds to 80 seconds. At this time, the ultraviolet light 160 is 5 seconds at a low power of 20 W / cm 3 to 30 W / cm 3, preferably 25 W / cm 3 for 80 seconds at a high power of 850 W / cm 3 to 870 W / cm 3, preferably 860 W / cm 3. Investigate while. As described above, when the surface of the fifth photoresist pattern 150 is exposed to the ultraviolet rays 160 according to the method of the present invention, the surface area of the fifth photoresist pattern 150 is changed to hydrophilic and thus the nitride membrane ( The adhesiveness with the 118 may be excellent to accurately form the via hole 129 and the via contact 132. Therefore, when the first sacrificial layer 112 is later etched using hydrogen fluoride, the protective layer 106 may be etched to prevent undercuts from occurring in the via hole 129.

Subsequently, the via hole 129 is formed by etching the lower electrode 121, the membrane 118, the etch stop layer 109, and the protective layer 106 from the strained layer 124 through the opening 155.

Referring to FIG. 7E, after removing the fifth photoresist 150, the drain pad 110 and the lower electrode 11 may be formed in the via hole 129 by sputtering a metal such as tungsten, platinum, or titanium. The via contact 132 is formed so that 121 is electrically connected. Accordingly, the via contact 132 is vertically formed from the lower electrode 121 to the top of the drain pad 103 in the via hole 129. Therefore, the image signal is applied to the lower electrode 121 through the drain pad 103 and the via contact 132 from the transistor embedded in the active matrix 100. Subsequently, a metal such as chromium (Cr), copper (Cu), or gold (Au) is deposited on the bottom of the active matrix 100 using an evaporation or sputtering method to form a resistive contact (not shown). do. Then, after coating a sixth port resist (not shown) on the active matrix 100, a bias voltage is applied to the upper electrode 127, which is a subsequent common grain, and an image is applied to the lower electrode 121, which is a signal electrode. The active matrix 100 is cut in preparation for a tape carrier package (TCP) bonding for applying a signal. At this time, the active matrix 100 is cut out only to a predetermined thickness for subsequent processing. Subsequently, the pad portion of the AMA panel is etched using a dry etching method to expose a pad (not shown) of the AMA panel required for TCP bonding. The first sacrificial layer 112 is etched with hydrogen fluoride vapor to form a first air gap 115.

Referring to FIG. 7F, after forming the first air gap 115 as described above, the second sacrificial layer 138 is formed on the entire surface of the resultant. The second sacrificial layer 138 facilitates the mounting of the mirror 146 and improves the horizontality of the mirror 146. The second sacrificial layer 138 is formed by spin coating a polymer having good fluidity, and has a constant thickness with respect to the upper electrode 127 while completely filling the first air gap 11 and the via hole 129. Apply to have. As such, when the second sacrificial layer 138 is applied to the entire surface of the resultant on which the actuator 135 is formed, the second sacrificial layer 138 is filled in the first air gap 115 and the via hole 129 and is flat. To form a surface.

Subsequently, the second sacrificial layer 138 is patterned using a seventh photoresist (not shown) as a mask to expose an upper portion of one side of the upper electrode 127. Subsequently, a metal such as aluminum, silver, or platinum is sputtered on the exposed upper electrode 127 and the second sacrificial layer 138 to a thickness of about 0.1 μm to 1.0 μm. The lower side of the sputtered metal is supported by the mirror post 143 and the mirror post 143 formed on one side of the upper electrode 127, and the other side is mounted in parallel with the upper electrode 127. The mirror 146 is formed. The mirror 146 is inclined at an angle with the actuator 135 to reflect the light beam incident from the light source. ₂

After the active matrix 100 having the thin film AMA element is completely cut into a predetermined shape as described above, the pad of the AMA panel and the TCP are connected to complete manufacture of the thin film AMA module. The deformation layer 124 causes deformation. do.

The strained layer 124 shrinks in a direction perpendicular to the electric field. Accordingly, the actuator 135 including the deformation layer 124 is bent at a predetermined angle, and the mirror 146 mounted on the upper electrode 127 of the actuator 135 is attached to the bent upper electrode 127. As a result, the axis is moved and tilted to reflect the light beam incident from the light source. The light beam reflected by the mirror 146 is projected onto the screen through the slit to form an image.

As described above, according to the manufacturing method of the thin film type optical path control device according to the present invention, by exposing the surface of the photoresist to ultraviolet light, the surface portion of the photoresist is changed to hydrophilic, and thus the adhesion to the thin film, in particular the nitride membrane It was excellent enough to form via holes and via contacts accurately. Therefore, when the sacrificial layer is etched using hydrogen fluoride, a portion of the protective layer is etched together to prevent undercuts from occurring in the via holes.

Claims (6)

Providing an active matrix having M × N (M, N is an integer) transistors and a drain pad formed on one side thereof; Forming an actuator on the active matrix, the actuator including a membrane, a lower electrode, a strained layer, and an upper electrode; Patterning the upper electrode, the strain layer, and the lower electrode; Applying a photoresist on top of the patterned upper electrode, the deforming layer and the lower electrode, and then irradiating the photoresist with ultraviolet light; And forming a via contact connecting the drain pad and the lower electrode to one side of the actuator. The method of claim 1, wherein forming the membrane comprises: i) forming a protective layer on top of the active matrix and the drain pad, ii) forming an etch stop layer on top of the protective layer, and iii And forming a first sacrificial layer on the etch stop layer, and then patterning the first sacrificial layer to expose a portion where the drain pad is formed below the etch stop layer. Method of manufacturing the device. The method of claim 1, wherein the irradiating with ultraviolet rays is performed for 10 seconds to 35 seconds while heating the photoresist to a temperature of 105 ° C. to 120 ° C. first, and then the photoresist to 145 ° C. The method of manufacturing a thin film type optical path control device further comprising the step of performing for 40 to 80 seconds while heating to a temperature of 170 ℃. The thin film type as claimed in claim 3, wherein the irradiating with ultraviolet rays is performed for 80 seconds at a high power of 850 W / cm 3 to 870 W / cm 3 and for 5 seconds at a low power of 20 W / cm 3 to 30 W / cm 3. Method of manufacturing the optical path control device. The method of claim 1, wherein the forming of the via contact comprises sequentially etching the patterned upper electrode, the patterned strain layer, and the patterned lower electrode to vertically via the strain pad to an upper portion of the drain pad. A method of manufacturing a thin film type optical path control device, characterized in that performed after the step of forming a hole. The method of claim 1, wherein forming the via contact comprises: a) patterning the membrane, b) the patterned top electrode, the patterned strain layer, the patterned bottom electrode, and the top of the patterned membrane Forming a second sacrificial layer on the substrate, c) patterning the second sacrificial layer to expose an upper portion of one side of the upper electrode, and d) aluminum and platinum on the exposed upper electrode and the second sacrificial layer. And sputtering any one selected from the group consisting of silver, e) simultaneously forming a mirror support and a mirror by patterning any one selected from the group consisting of the sputtered aluminum, platinum and silver, and f) the second After removing the sacrificial layer using an oxygen plasma, the thin film type optical path control further comprises the step of cleaning and drying Method of manufacturing the device.