KR19980057865A - Particle Monitoring Method of Thin Film Light Path Controller - Google Patents

Abstract

Disclosed is a particle monitoring method of a thin film type optical path control device. The method includes providing an active matrix having M × N (M, N is an integer) transistors and having a drain pad formed thereon, a membrane, a lower electrode, a strained layer on top of the active matrix and the drain pad; Forming an upper electrode, patterning each of the upper electrode, the deformation layer, and the lower electrode so that both sides thereof have a quadrangular shape, and one side of the center part has a plurality of irregularities, and the patterned Determining whether particles are present in the upper electrode, the strained layer, and the lower electrode through an upper electrode, the patterned strained layer, and the patterned lower electrode. According to the above method, by deforming the shapes of the thin films constituting the actuator formed on the active matrix, it is possible to easily check the presence of the particles formed in the thin films.

Description

Particle Monitoring Method for Thin-Film-Type Optical Path Control

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a particle monitoring method of a thin film type optical path control device using Actuated Mirror Arrays (AMA), and more particularly, to a method of particle formation in thin films constituting an actuator formed on an active matrix. The present invention relates to a particle monitoring method of a thin film type optical path control device that can easily monitor the presence or absence of light. The optical beam is reflected at a defined angle, and the light beam is adjusted so that the reflected light beam passes through a slit to form an image on the screen. It is a device that can. AMA has a simple structure and operation principle, and has an advantage of obtaining high light efficiency compared to a liquid crystal display device or a DMD. In addition, AMA enhances contrast, resulting in brighter and clearer images. The AMA is mounted on an embedded active matrix, processed by sawing, and a mirror mounted on top. However, in the bulk type device, actuators must be separated by a sawing method, which requires very high precision in design and manufacturing and has a disadvantage in that the response speed of the deformable part is slow. Therefore, a thin film type optical path control device that can be manufactured using a semiconductor manufacturing process has been developed.

The thin film type optical path control apparatus is disclosed in Patent Application No. 96-33608 (name of the invention: thin film type optical path control apparatus and manufacturing method having an improved reflectance) which the applicant has applied for a patent on August 13, 1996.

FIG. 2 is a plan view of the thin film type optical path adjusting device described in the preceding application, FIG. 3 is a cross-sectional view taken along line AA ′ of the device shown in FIG. 2, and FIGS. 4A to 4C are shown in FIG. 3. It is a manufacturing process diagram of one apparatus.

As shown in FIG. 2 and FIG. 3, the thin film type optical path adjusting device includes an active matrix 61 and an actuator 77 formed on the active matrix 61. The active matrix 61 includes M × N (M and N are integers) MOS (Metal Oxide Semiconductor) transistors (not shown) and a drain pad 62 formed on one side thereof. A passivation layer 63 formed on the drain pad 62 and the active matrix 61, and an etch stop layer 65 formed on the passivation layer 63.

The active matrix 61 is made of a semiconductor such as silicon (Si) or an insulating material such as glass or alumina (Al ₂ O ₃ ). The protective layer 63 for protecting the surface of the active matrix 61 in which the transistor is embedded prevents the active matrix 61 from being damaged during the subsequent process. An etch stop layer 65 formed on the passivation layer 63 prevents the active matrix 61 and the passivation layer 63 from being etched by a subsequent etching process.

In addition, as shown in Figure 2, the plane of the membrane 67, one side has a concave portion of the rectangular shape around the center of the membrane 67, the concave portion is stepped wide to both edges It is formed in the shape of a paper, and has a protruding portion that is narrowed toward the center of the membrane so that the other side corresponds to the stepped concave portion of the membrane of the adjacent actuator. Thus, the protrusion of the membrane 67 is formed by fitting into the concave portion of the adjacent membrane, and the protrusion of the membrane adjacent to the concave portion of the membrane 67 is sandwiched. The lower electrode 69 which is a signal electrode is an image signal. Is applied through the drain pad 62 and the via contact 72 from a transistor embedded in the active matrix 61. It is formed from dielectric layers having two or more different indices of refraction thickness. Thereby, the light beam incident from the light source is reflected by the reflective layer 75 formed as described above.

Referring to FIG. 4A, a protective layer 63 is stacked on an active matrix 61 having M × N MOS transistors embedded therein and a drain pad 62 formed on one side thereof. The protective layer 63 is formed of Phospho-Silicate Glass (PSG) to have a thickness of about 1.0 to 2.0 μm by chemical vapor deposition (CVD). Subsequently, an etch stop layer 65 is stacked on the passivation layer 63. The etch stop layer 65 is formed to have a thickness of about 1000 to 2000 kPa using a low pressure chemical vapor deposition (LPCVD) method. A sacrificial layer is formed on the etch stop layer 65. 66 are laminated. The sacrificial layer 66 is formed to have a thickness of about 1.0 to 2.0 μm by using the silicate glass (PSG) by the atmospheric pressure chemical vapor deposition (APCVD) method. Subsequently, a portion of the sacrificial layer 66 in which the drain pad 62 is formed is patterned to expose a portion of the etch stop layer 65. _{3 3}

The upper electrode 73 is formed on the deformation part 71. The upper electrode 73 is formed to have a thickness of about 0.1 μm to 1.0 μm using a sputtering method such as aluminium, silver, or platinum. Then, the upper electrode 73 is patterned in a school shape to form a stripe 74 on a part of the upper electrode 73.

Referring to FIG. 4C, a reflective layer 75 is stacked on the upper electrode 73. The reflective layer 75 is formed of a dielectric such as TiO ₂ or SiO ₂ using a chemical vapor deposition (CVD) method. When the reflective layer 75 is formed, the reference wavelength for each R, G, and B is formed for each AMA element formed for each of R, G, and B so as to correspond to the luminous flux spectra according to the R, G, B color system after being incident from the light source. λ) It is formed to have a reflective layer 75 comprising two or more dielectric layers having different refractive indices of twice the thickness. Subsequently, the strain portion 7l, the lower electrode 69, the membrane 67, the etch stop layer 65, and the protective layer 63 are sequentially etched to form a via contact 72. The via contact 72 is vertically formed from the deformation portion 71 to the drain pad 62 by using a lift-off method of tungsten or titanium. The sacrificial layer 66 is etched using hydrogen fluoride (HF) vapor, and then washed and dried to complete the device.

In the above-described thin film type optical path adjusting device, an image signal is applied from the MOS transistor embedded in the active matrix 61 to the lower electrode 69 which is a signal electrode through the drain 62 pad and the via contact 72. At the same time, a bias voltage is applied to the upper electrode 73, which is a common electrode, to generate an electric field between the upper electrode 73 and the lower electrode 69. By this electric field, the deformation portion 71 between the upper electrode 73 and the lower electrode 69 causes deformation. The deformation portion 71 contracts in a direction perpendicular to the electric field, so the actuator 77 is bent in a direction opposite to the direction in which the membrane 67 is formed at a predetermined angle. The reflective layer 75 formed corresponding to the reference wavelengths spectroscopically measured by the R · G · B colorimetric system is inclined together with the actuator 77 because it is formed on the actuator 77. Accordingly, the reflective layer 75 reflects the light beam incident from the light source at a predetermined angle, and the reflected light flux passes through the slit to form an image on the screen.

However, while manufacturing the thin film type optical path control apparatus as described above, it is difficult to determine whether particles are formed in the thin films constituting the actuator formed on the active matrix. When particles are formed in the thin films, the tilting angle is lowered in the case of the strained layer, and the bias voltage and the image signal voltage are not sufficiently applied in the case of the upper electrode and the lower electrode, so that the strained layer causes the strain. The required electric field does not occur or an electrical short occurs. As such, the presence or absence of particles formed in the strained layer, the upper electrode, and the lower electrode greatly affects the performance of the device. Therefore, the identification method of particles present in the thin films is an important process for identifying the characteristics of the device. In the related art, after fabricating the device, a destructive method using an electron microscope or an indirect method through sampling is used. However, these methods have a problem in that the characteristics of the device may be degraded or the presence of particles may not be accurately determined for each device.

1 is a schematic diagram of an engine system of a conventional optical path control apparatus.

2 is a plan view of a thin film-type optical path control device previously applied by the present applicant.

5 is a plan view of a thin film type optical path control apparatus according to the present invention.

In order to achieve the above object, the present invention provides a method comprising: providing an active matrix in which M × N (M, N is an integer) transistors are formed and a drain pad is formed thereon; Forming a membrane, a lower electrode, a strained layer, and an upper electrode on top of the active matrix and the drain pad; Patterning each of the upper electrode, the strain layer, and the lower electrode so that both sides have a rectangular shape and one side of the center part has a plurality of irregularities; And checking the presence of particles in the upper electrode, the strain layer, and the lower electrode through the patterned upper electrode, the patterned strain layer, and the patterned lower electrode. It is also possible to determine whether particles are formed between both sides of the phase in the same manner as described above. In addition, when a short occurs by applying a current to one of both sides of the quadrangular shape of the upper electrode and the center of the lower electrode, it can be seen that particles exist within the strained layer.

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

5 is a plan view showing a thin film type optical path control device according to the present invention, Figure 6 is a cross-sectional view taken along the line BB 'of the device shown in Figure 5, Figures 7a to 7c is shown in FIG. It is a manufacturing process diagram of an apparatus.

5 and 6, the thin film type optical path control apparatus according to the present invention has an active matrix 100 having a drain pad 105 formed thereon and an upper portion of the active matrix 100. Actuator (160) formed.

The active matrix 100 may include a passivation layer 110 formed on the active matrix 100 and the drain pad 105, and an etch stop layer formed on the passivation layer 110. The active matrix 100 is formed of a semiconductor substrate such as silicon (Si), or an insulating material such as glass or alumina (Al ₂ O ₃ ). The active matrix 100 includes M x N (M, N is an integer) MOS transistors (not shown). The protective layer 110 is made of phosphorus silicate glass (PSG), and has a thickness of about 1.0 to 2.0 μm. The protective layer 110 serves to protect the active matrix 100 during subsequent processes. The etch stop layer 115 is formed of nitride and prevents the protective layer 110 and the active matrix 100 from being etched and damaged during the subsequent etching process. The electrode 135 is formed in the same shape.

The membrane 130 is made of nitride and has a thickness of about 0.1 to 1.0 μm, and the lower electrode 135 is made of metal such as platinum (Pt), tantalum (Ta), or platinum-tantalum (Pt-Ta). It has a thickness of about 0.1 to 1.0 μm. An image signal is applied to the lower electrode 135, which is a signal electrode, through the drain pad 105 and the via contact 155 from a transistor embedded in an active matrix. The strained layer 140 is made of a piezoelectric material such as PZT or PLZT and has a thickness of about 0.1 μm to 1.0 μm, preferably about 0.4 μm.

The upper electrode 145 is made of metal such as platinum, tantalum, aluminum, or silver and has a thickness of about 0.1 μm to about 1.0 μm. A bias voltage is applied to the upper electrode 145 which is a common electrode. When an image signal is applied to the lower electrode 135 and a bias voltage is applied to the upper electrode 145 at the same time, an electric field is generated between the lower electrode 135 and the upper electrode 145, and the strained layer 140 is caused by the electric field. The deformation occurs at this predetermined tilting angle.

The mirror 175 is made of metal such as platinum, aluminum, or silver and has a thickness of about 0.1 μm to about 1.0 μm. The mirror 175 is tilted together with the upper electrode 145 to reflect the light beam incident from the light source.

Hereinafter, the method of manufacturing the above-described thin film type optical path control apparatus will be described in detail with reference to the drawings. A protective layer 110 is stacked on the upper portion of the switch 100. The protective layer 110 is formed to have a thickness of about 1.0 to 2.0 μm using the phosphorus silicate glass (PSG) using a chemical vapor deposition (CVD) method. The protective layer 110 protects the active matrix 100 in which the transistor is embedded during subsequent processing. An etch stop layer 115 is stacked on the passivation layer 110.

The etch stop layer 115 is formed to have a thickness of about 2000 to 4000 mV, preferably about 3000 mV, using a low pressure chemical vapor deposition (LPCVD) method. The etch stop layer 115 prevents the active matrix 100 and the protective layer 110 from being etched during the subsequent etching process. The etch stop layer 115 is formed to have a thickness of about 0.1 μm to about 1.0 μm, preferably about 4000 μm. Subsequently, a lower electrode 135 made of a metal such as platinum, tantalum, or platinum-tantalum is stacked on top of the membrane 130. The lower electrode 135 is formed to have a thickness of about 0.1 μm to about 1.0 μm, preferably about 1200 μs, using a sputtering method. Subsequently, Iso-Cutting is performed to separate the lower electrode 135 for each pixel. The strained layer 140 is stacked on the lower electrode 135. Deformation layer 140 is a piezoelectric material such as PZT, PLZT, etc. using a sol-gel (Sol-Gel) method, sputtering method, or chemical vapor deposition (CVD) method 0.1 to 1.0μm, preferably about 0.4μm It is formed to have a thickness of. Subsequently, the strained layer 140 is heat-transferred using a rapid thermal annealing (RTA) method to phase change.

The upper electrode 145 is formed on the strained layer 140. The upper electrode 73 is formed to have a thickness of 500 to 2000 mW, preferably 500 mW, using a metal such as platinum tantalum, aluminum, or silver by a sputtering method.

Referring to FIG. 7B, the upper electrode 145, the strained layer 140, and the lower electrode 135 are patterned in sequence. That is, after applying a photo resist (not shown) on the upper electrode 145, both sides of the upper electrode 145 has a rectangular shape, one side of the central portion has a plurality of irregularities (凹凸) ) Is then patterned to have a shape, and then the photoresist is removed. In this manner, the strained layer 140 and the lower electrode 135 are patterned in sequence. Thus, the strained layer 140 has the same shape as that of the upper electrode 145 and has a slightly wider shape. In addition, the lower electrode 135 also has the same shape as the strained layer 140 and has a wide shape. Subsequently, the pad (not shown) of the AMA panel and the pad (not shown) of the TCP are connected to complete manufacturing of the thin film AMA module.

Hereinafter, a particle monitoring method of a thin film type optical path adjusting device manufactured according to the above method will be described.

Referring to FIG. 5, when a rectangular shape of the upper electrode 145 is applied to both sides C and D, the upper electrode 145 is disposed between both sides (between C and D) of the upper electrode 145. If particles are formed during the formation of the current, the current is short-circuited. On the contrary, if no particles exist between both sides of the upper electrode 145, the current is not shorted. The deformation layer 140 and the lower electrode 135 may also check whether particles are formed between both sides of the rectangular shape in the same manner as described above.

Therefore, according to the particle monitoring method of the thin film type optical control device according to the present invention, the actuator is configured during the process of manufacturing the device on the top of the active matrix to deform the shape of the thin films, so that the particles formed inside the respective thin films The presence can be easily confirmed. Therefore, the presence of particles can be accurately identified without degrading the characteristics of the device in a destructive manner, so that the characteristics of the device can be grasped.

Claims (5)

Providing an active matrix having M × N (M, N is an integer) transistors and a drain pad formed thereon; Forming a membrane, a lower electrode, a strained layer, and an upper electrode on top of the active matrix and the drain pad; Patterning each of the upper electrode, the strain layer, and the lower electrode so that both sides have a rectangular shape and one side of the center part has a plurality of irregularities; And checking the presence or absence of particles in the upper electrode, the strain layer, and the lower electrode through the patterned upper electrode, the patterned strain layer, and the patterned lower electrode. Way. The method of claim 1, wherein providing the active matrix comprises: i) forming a protective layer over the active matrix and the drain pad, ii) forming an etch stop layer over the protective layer, iii And forming a sacrificial layer on top of the etch stop layer, and etching the sacrificial layer to expose a portion where the drain pad is formed under the etch stop layer. Monitoring method. The method of claim 2, wherein the patterning of the lower electrode comprises: a) vertically etching the upper electrode, the strained layer, the lower electrode, and the membrane from one upper side of the upper electrode to the upper portion of the drain pad; Forming a hole, b) forming a via contact inside the via hole using a lift-off method, c) patterning the membrane, and d) using the hydrogen fluoride vapor to form the sacrificial layer. Particle monitoring method of the thin film type optical path control device further comprising the step of removing. The method of claim 1, wherein the determining of the presence of the particles comprises applying current to both sides having a rectangular shape of the patterned upper electrode, the patterned strain layer, and the patterned lower electrode. Particle monitoring method of the thin film type optical path control device further comprising the step of identifying. The method of claim 1, wherein the determining of the presence of the particles comprises applying a current to any one of both sides having a quadrangular shape of the patterned upper electrode and the other side of the center of the patterned lower electrode. Particle monitoring method of the thin film type optical path control device further comprising the step of identifying.