KR19980057859A - Test pattern formation method of thin film type optical path control device - Google Patents

Abstract

A test pattern forming method of a thin film type optical path control device is disclosed. The method includes providing an active matrix containing M × N transistors, forming a plurality of test patterns on an upper edge of the active matrix, and forming M × N drain pads on top of the active matrix. Forming a membrane on top of the active matrix and the drain pad, forming a lower electrode on top of the membrane, forming a strained layer on top of the lower electrode, on top of the strained layer Forming an upper electrode, and patterning the upper electrode, the strain layer, the lower electrode, and the membrane. According to the method, during the fabrication of the device on top of the active matrix, in order to accurately determine the type of stress each thin film constituting the actuator receives, a test pattern having a different shape according to the stress is formed. Can be easily identified and eliminated to improve the performance of the actuator.

Description

Test pattern formation method of thin film type optical path control device

The present invention relates to a method for forming a test pattern of a thin film type optical path control device using Actuated Mirror Arrays (AMA), and more particularly, depending on the stresses of the thin films constituting the actuator during formation of each element on the active matrix. The present invention relates to a method of forming a test pattern of a thin film type optical path control device capable of identifying a process variable and improving device performance by forming a test pattern having a shape. (7), it is reflected by the second mirror 8 and the third mirror 9 and is incident on the AMA elements 13, 15 and 17 corresponding to each mirror. The AMA elements 13, 15, and 17 formed by R, G, and B each incline the mirror provided therein at a predetermined angle to reflect the incident light beam. At this time, the mirror is inclined according to the deformation of the deformation portion formed in the lower portion of the mirror. The light reflected from the AMA elements 13, 15, 17 passes through the second lens 19 and the second slit 21, and then is projected to a screen (not shown) by the projection lens 23. FIG. 2 shows a plan view of the thin film type optical path adjusting device described in the preceding application, and FIG. 3 shows a cross-sectional view taken along the line AA ′ of the device shown in FIG. FIG. 4C is a manufacturing process diagram of the apparatus shown in FIG. 3, and FIG. 5 shows a plan view of the apparatus shown in FIG. 3 arranged in M × N on an active matrix, and FIG. 6 is one of the apparatus shown in FIG. A plan view of a test pattern for indicating stress of a thin film is illustrated, and FIG. 7 is a cross-sectional view of the test pattern illustrated in FIG. 6. _One side is in contact with _{2 3} and the other side is a lower electrode (bottom) formed on the membrane 67, the membrane (67) having a cross section formed in parallel with the active matrix 61 via the air gap 68 electrode 69, an active layer 71 formed on an upper portion of the lower electrode 69, a top electrode 73 and an upper electrode 73 formed on one side of the deformation portion 71. From the other side of the reflective layer 75 formed on the upper portion of the deformable portion 71 to the drain pad 62 through the lower electrode 69, the membrane 67, the etch stop layer 65 and the protective layer 63 It includes a vertically formed via contact 72.

A stripe 74 is formed on a part of the upper electrode 73 which is a common electrode to which a bias voltage is applied. The stripe 74 operates the upper electrode 73 uniformly to prevent diffuse reflection of the light beam incident from the light source. When an image signal is applied to the lower electrode 69 as a signal electrode and a bias voltage is applied to the upper electrode 73 as a common electrode, an electric field is generated between the upper electrode 73 and the lower electrode 69. By this electric field, the deformation | transformation part 71 produces a deformation | transformation in the direction perpendicular | vertical to an electric field. The reflective layer 75 is formed by two or more of each AMA element formed by R, G, and B so as to correspond to the light beams spectroscopically measured according to the R, G, and B colorimeters, each of which is ¼ times the thickness of the reference wavelength? It is formed of dielectric layers having different refractive indices. As a result, the light beam incident from the light source is reflected by the reflective layer 75 formed as described above.

Referring to FIG. 4B, the membrane 67 is stacked on the exposed etch stop layer 65 and on the sacrificial layer 66. The membrane 67 is formed to have a thickness of about 0.1 to 1.0 μm using a low pressure chemical vapor deposition (LPCVD) method. Subsequently, a lower electrode 69 made of platinum (Pt), platinum-tantalum (Pt-Ta), or the like is stacked on the membrane 67. The lower electrode 69 is formed to have a thickness of about 0.1 μm to about 1.0 μm by using a sputtering method. _{3 3 2 2 The} contact 72 is formed vertically from the deformation portion 71 to the drain pad 62 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.

However, during the manufacture of the thin film type optical path control apparatus as described above, the test pattern formed on the upper edge of the active matrix is a compressive stress in order to visually confirm the type of stress received by the thin films constituting the actuator formed on the active matrix. Although (compressive stress) is visualized, tensile stress is difficult to express. That is, as shown in FIGS. 5 to 7, the test pattern 90a representing the stress applied to the thin film among the test patterns 90, 91, 92, and 93 formed on the active matrix 61. Since the cross section is clamped by both supporting portions and two rectangular openings are formed inside the test pattern 90a, compressive stresses received from both sides can be expressed through the openings, but tensile stresses are difficult to express. There is a problem. As a result, the shape of the stress applied to the thin films constituting the actuator may not be accurately understood, which is a limitation in improving the performance of the actuator 160.

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

In order to achieve the above object, the present invention, forming a lower electrode on the membrane;

8 illustrates a plan view of a thin film type optical path adjusting device according to the present invention, wherein the upper electrode, the strained layer, the lower electrode, and the membrane are patterned. FIG. 10A to 10F are manufacturing process diagrams of the apparatus shown in FIG. 9, and FIG. 11 shows a plan view of an active matrix in which the apparatus shown in FIG. 9 is arranged in M × N. 11 is an enlarged plan view of a test pattern for displaying a stress of a thin film among the apparatus illustrated in FIG. 11, and FIGS. 13A to 13B are plan views illustrating a state in which the test pattern illustrated in FIG.

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. 115. ₂₃ pads are in contact with the portion 105 is formed, the other side of the first air gap 125, the membrane having formed parallel to cross section and the etching stop layer 115 via the (membrane) 130, the membrane 130 A bottom electrode 135 formed on the upper portion, an active layer 140 formed on the lower electrode 135, and a top electrode 145 formed on the deformation layer 140. The drain pad 105 may be perpendicular to the drain pad 105 through the lower electrode 135, the membrane 130, the etch stop layer 115, and the protective layer 110. And the via contact 150 formed in the via hole 150. The via contact 150 is applied through the drain pad 105 and the via contact 155 from a transistor embedded in the via 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 about 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. 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 1.0 μm, preferably about 0.4 μm. The upper electrode 145 is formed on the strained layer 140. The upper electrode 73 is formed to have a thickness of about 0.1 μm to 1.0 μm using a sputtering method of a metal such as platinum, tantalum, aluminum, or silver. Subsequently, 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, after patterning the upper electrode 145 to have a predetermined pixel shape, the photo resist is removed. In this manner, the strained layer 140 and the lower electrode 135 are sequentially patterned. FIG. 10D is a view illustrating a patterned state after the second sacrificial layer 185 is formed. Referring to FIG. 10D, after forming the first air gap 125 as described above, a second sacrificial layer 165 is formed on the entire surface of the resultant. The second sacrificial layer 165 forms a polymer having excellent fluidity to a predetermined height above the upper electrode 145 by using a spin coating method, so that the first air gap l25 and the via hole 150 are formed. Will be filled. Subsequently, the second sacrificial layer 165 is patterned to expose an upper portion of one side of the upper electrode 145. ₂

In order to visually confirm the influence, two rectangular openings were formed in the test pattern for stress display of the thin film among the test patterns formed on the upper edge of the active matrix. In this case, compressive stresses received from both sides can be expressed through the openings, but tensile stresses are difficult to express. In contrast, in the present invention, two vertical openings are formed in the stress display 200a of the thin film, and two horizontal openings are formed adjacent to each other. That is, the inside of the stress display test pattern 200a of the thin film is formed to have a 'I' shape. Accordingly, as shown in FIG. 13A, when the compressive stress is applied, the two openings in the vertical direction contract along the direction in which the compressive stress is applied, and two horizontal openings formed on both sides of the openings in the vertical direction are expanded. The compressive stress is applied to the thin film. The active matrix 100 is cut in preparation for TCP bonding to apply an image signal. In this case, the active matrix 100 is cut out only to a predetermined thickness in preparation for the subsequent process. 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.

The image signal transmitted from the pad of the AMA panel is applied to the lower electrode 135 through the MOS transistor, the drain pad 105, and the via contact 155 embedded in the active matrix 100. At the same time, a bias voltage is applied to the upper electrode 145 to generate an electric field between the upper electrode 145 and the lower electrode 135. The strained layer 140 between the upper electrode 145 and the lower electrode 135 causes deformation by this electric field. The strained layer 140 contracts in a direction perpendicular to the electric field, and thus the actuator 160 including the strained layer 140 is bent at a predetermined angle. The mirror 175 formed on the actuator 160 is tilted at a predetermined angle with the tilting layer 140 tilted to reflect the light beam incident from the light source, and the reflected light beam passes through the slit and is projected onto the screen. And bear an image.

Therefore, according to the test pattern forming method of the thin film type optical path control apparatus according to the present invention, in order to accurately determine the type of stress each thin film constituting the actuator during the process of manufacturing the device on the active matrix, compression and tension By forming test patterns representing different shapes according to stress, the stress can be easily identified and eliminated to improve the performance of the actuator.

Claims (4)

Providing an active matrix containing M × N (M, N is an integer) transistors; The test of claim 1, wherein the forming of the test pattern further comprises forming a test pattern for an active matrix and forming a test pattern for displaying a stress of the thin film. How to form a pattern. The method of claim 2, wherein the displaying of the stress display test pattern comprises: forming a plurality of vertical openings in the stress display test pattern and a plurality of openings on both sides of the plurality of longitudinal openings. The test pattern forming method of the thin film type optical path control device further comprising the step of forming an opening in the horizontal direction. 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, i) Forming a first sacrificial layer on top of the etch stop layer, and iv) patterning the first sacrificial layer to expose a portion of the etch stop layer under which the drain pad is formed, The patterning may include: a) forming a via hole by etching the strain layer, the lower electrode, the membrane, the etch stop layer, and the protective layer from a portion of the strain layer in which the drain pad is formed below, b) And forming a via contact connecting the lower electrode and the drain pad in the via hole, and patterning the membrane. The method may include forming a second sacrificial layer on the patterned upper electrode, patterning the second sacrificial layer to expose an upper portion of one side of the upper electrode, and exposing the exposed upper electrode and the second sacrificial layer. Sputtering platinum, aluminum, or silver on top of the layer, patterning the sputtered platinum, aluminum, or silver to form a mirror on top of the upper electrode, and removing the second sacrificial layer Method of forming a test pattern of the thin film type optical path control device further comprising.