TWI289700B - Method of fabricating a liquid crystal-on-silicon backplane - Google Patents

Abstract

A reflective mirror layer is formed over a silicon substrate and is then selectively etched to define a crossover pad region, a pixel array region, and a bonding pad region on the silicon substrate. A dielectric layer is deposited over the crossover pad region, the pixel array region and the bonding pad region, and a plurality of crossover pad vias are formed within the crossover pad region thereafter. By filling the crossover pad vias with conductive material, a plurality of plugs is formed in the plurality of the vias. Then, a top pad, electrically coupled to the bottom pad via the plugs, is formed over the crossover pad region. A spacer pattern on the dielectric layer within the pixel array region is defined thereafter. Finally, the dielectric layer is etched to form a plurality of spacers within the pixel array region.

Description

1289700 V. INSTRUCTION DESCRIPTION OF THE INVENTION (1) Field of the Invention The present invention provides a method for producing a backplane by using a solar crystal liquid crystal (LCD), in particular, a same day. A method of displaying a spacer and a crossover pad of the backplane. BACKGROUND OF THE INVENTION The Si Xijing liquid crystal microdisplay (m i c r ο - d i s p 1 a y ) is a key technology of a reflective LCoS projector and a rear-projection television. The biggest advantage of the LCo tender display is that it can significantly reduce panel production costs, small size, and has high resolution and low power. Different from the thin film transistor-liquid crystal isplay 'TFT-LCD', the upper and lower sides of the TFT-LCD are based on the slope of the glass, but the LCoSj has the glass on the top. The underlying substrate is based on semiconductor materials, so the LCoS process is a technology that combines LCD and semiconductor complementary metal-oxide semiconductor (CMOS) processes. In today's LCoS technology, it can be roughly divided into two types: transmissive and reflective. Layer In the LCD device, in order to obtain stable display quality, liquid

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The thickness ′ or the gap (the gap between the transparent conductive substrate and the semiconductor substrate) must be accurately controlled to a certain value. In the process of the conventional liquid crystal display panel device, in order to maintain the gap, plastic bead, glass beads, or glass fibers are usually placed between the two substrates as a spacer. Therefore, the gap size is defined by the high yield of the spacer. In the process of the conventional LCD device, the spacer system is placed in a spray pattern, so that the position of the spacer between the liquid crystal display substrates cannot be properly controlled. Thus, there may be The spacer appears in the light transmitting region, so that the light is scattered by the gate spacer, thereby degrading the display quality. Moreover, since the spacer has a possibility of uneven distribution, it also causes the spacer to be clustered. In part, the display quality is degraded. At the same time, the maintenance of the gap size will be difficult. Moreover, the display specifications produced in the same batch (ba t ch ) or between different batches will be inconsistent, so Seriously affect the yield of the product and increase the cost of production. In addition, due to the size and cost of the microdisplay, the drive circuit in the integrated circuit is usually integrated into the pixel transistor. The display backplane, that is, the drive circuit is directly fabricated on the substrate, rather than being designed as a large external drive circuit as in the conventional LCD. In the technique, the process is performed after the spacer is placed, and then the electrode of the upper transparent conductive substrate is soldered to the inner circuit board in a backend assembly process.

V. INSTRUCTIONS (3) Since the conventional method uses a spraying method to place the bead spacers, the position of the spacer formed by the method will not be fixed, and the distribution thereof may be uneven, and at the same time, The product specifications will not be uniform. Therefore, the way in which the spacers are placed or the form must be improved to improve the product quality. In addition, if the process of LCoS display is further integrated in the process of using the increasingly mature CMOS technology, it can effectively reduce the production cost. SUMMARY OF THE INVENTION It is therefore a primary object of the present invention to provide a method of making a twin crystalline liquid crystal display backsheet to solve the above-described problems of conventional fabrication methods. In a preferred embodiment of the present invention, a reflective mirror layer is first formed on a semiconductor substrate, and then the mirror layer is selectively etched to define a jumper pad region on the semiconductor substrate. a Pixel array region and a padding region, wherein the jumper pad region includes a bottom pad formed by the mirror layer. The pixel array region includes A plurality of reflective cells formed by the mirror layer and a plurality of trenches are formed between the reflective cells, and the pad region includes at least one solder pad formed by the mirror layer. And filling a plurality of trenches with a filling material (gap fi 1 1 ing material ), and depositing on the jumper pad region, the image 1289700, the invention description (4) array region, and the pad region A dielectric layer. Forming a first photoresist layer on the dielectric layer, the first photoresist layer having a plurality of openings above the jumper pad region to define a jumper via hole (cr〇ss〇ver pad v 1 a) region, performing an etching process, etching the dielectric layer through the plurality of openings to form a plurality of via via vias in the dielectric layer of the jumper pad region, and then removing the first The photoresist layer is filled with a conductive material in the plurality of via holes to form a plurality of plugs. An upper conductive plate is then formed on the jumper region and electrically connected to the lower conductive plate via the plurality of plugs. Finally, a second photoresist layer is formed over the semiconductor substrate. The second photoresist layer shields the jumper pad region, and defines a plurality of spacers above the dielectric layer of the pixel array region. The dielectric layer is formed to form a plurality of spacers in the dielectric layer of the pixel array region to complete the fabrication of the Sihua crystal liquid crystal display backplane. Since the manufacturing method of the present invention is to produce a columnar spacer having a fixed position and a high degree of fixation on the back of the twinned liquid crystal display by means of photolithography and etching, it is possible to avoid the beading in the conventional method. The problem of unequal distribution of spacers creates an LCo% display that is precisely controlled and maintained. In addition, since the manufacturing method of the present invention is based on the LC〇S display backplane and the columnar spacer fish is simultaneously provided for the “road span”, the present invention does not need to be assembled in the later stage, and the electrode of the transparent transparent electric substrate is Soldering to the inner circuit board, such as: can reduce the process steps in the y name method, thereby improving the calving, reducing the cost

1289700 V. Description of invention

DETAILED DESCRIPTION OF THE INVENTION Referring to Figure 1, there is shown a schematic diagram of a rear-end structure of a crystalline liquid crystal microdisplay of the present invention. As can be seen from FIG. 1, the twinned liquid crystal microdisplay is mainly composed of a transparent conductive substrate 12, such as indium oxide (ΙΤ0) glass as the upper cover (c〇ver), and a semiconductor substrate 14 as Display the back panel. Wherein, a plurality of pixel arrays 16' are disposed on the display backplane, and a plurality of column spacers are formed at the non-pixel array position, and the plurality of column spacers are formed in the vicinity of the display panel. 2 2 is used to be freshly connected to the upper cover and has a plurality of jumper pads 24 at the corners for providing internal electrodes and a common electrode (not shown) of the upper cover (not shown). 2A to 2F, FIG. 2A to FIG. 2F are schematic diagrams showing a method for fabricating a crystalline liquid crystal display backplane on a surface of a semiconductor substrate 14. As shown in Fig. 2A, the method first forms a mirror layer 26 on a semiconductor substrate 4. In a preferred embodiment of the invention, the mirror layer 26 is a reflective aluminum layer, and other elements such as gold or silver can reflect light to form a virtual image, so that it faithfully reflects A real image material can also be used. In addition, after forming the mirror layer 26, the present invention may further form a reflection enhancement layer (not shown) on the mirror layer 26 for counteracting the semiconductor substrate. 14

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The resulting reflection suppression effect (inhibiting effeets, as shown in FIG. 2A, selectively etching the mirror layer 2 6 to define a jumper pad region 3 〇, a pixel array region 40 on the semiconductor substrate 14 And a pad region 50. The jumper pad region 3 includes a conductive plate 3 formed by the mirror layer 26, and the pixel array region 4 includes a plurality of reflective units 42 composed of the mirror layer 26. A plurality of trenches 44 are formed between the reflective units 42 and the pad region 5 includes at least one solder pad 5 formed by the mirror layer 26 and then filled with a filling material in the plurality of trenches 44. As shown in FIG. 2B, a dielectric layer 28 is then deposited over the jumper pad region 3, the pixel array region, and the pad region 5A. In the preferred embodiment of the invention, the dielectric layer 28 is It is composed of cerium oxide. Then, a first photoresist layer 46 is formed on the dielectric layer 28, and the first photoresist layer 46 is over the jumper pad region 30, and has a plurality of openings 3 2 to define a cross. Connect the via hole area. I8 is shown in Figure 2C, followed by one An etching process is performed to form a plurality of via holes through the openings 3 2 to form a plurality of via holes in the dielectric layer 28 of the jumper pad region 3, and then remove the first photoresist layer 46, and then remove the first photoresist layer 46. The jumper pad/same is inserted into the conductive material to form a plurality of plugs 34. In the most known example of the present invention, the conductive material for the plugs 34 can be made of tungsten or other metals. Tungsten plug or other metal plug.

1289700 V. Description of the Invention (7) As shown in FIG. 2D, an upper conductive layer is formed on the jumper pad region 3, and the upper conductive pad 36 has a top surface. It is higher than the top surface of the spacer and is electrically connected to the lower conductive plate 31 via a plurality of plugs 34. Since the jumper pad can be regarded as an electric path between the semiconductor substrate 4 and the transparent conductive substrate 12 (see FIG. 1), the top surface of the jumper should be slightly oriented to the top surface of the spacer to ensure compatibility. The transparent conductive substrate 丨 2 is in contact. In the preferred embodiment of the present invention, the upper conductive plate 36 can be formed by sputtering or sputtering of other V-electric materials such as metal or the like. Finally, as shown in FIG. 2E, a first photoresist layer 48 is formed over the semiconductor substrate 4, and the second photoresist layer 48 shields the jumper pad region 30 and above the dielectric layer 28 of the pixel array region 40. The positions of the plurality of spacers are defined, and the dielectric layer 2 is further illustrated. As shown in FIG. 2F, a plurality of column spacers 18 are formed in the dielectric layer 28 of the pixel array region 4. Moreover, when a plurality of column spacers 8 are formed in the dielectric layer 28 of the pixel array region 40, it is also possible to add, for example, a protective layer or the like, depending on the actual situation. At the same time, a plurality of openings 52 are etched into the dielectric layer 28 of the pad region 5, and the underlying pads are used for soldering. In addition, after forming a plurality of column spacers 18, a transparent conductive substrate 12 is covered on the semiconductor substrate 4, and the transparent conductive substrate 2 is electrically connected to the upper conductive pad 36 of the jumper pad region 3 Thus, the fabrication of the twin crystal liquid crystal display backplane is completed. In a general LCD device, the spacer is randomly scattered on the semi-V body substrate by spraying. If the position is placed in the developing area of the display

Page 11 1289700 V. Inventive Note (8) --- (viewing area), the contrast of the display will be reduced due to the appearance of the spacer, and the display quality will be degraded. In the Shixi 曰曰 liquid crystal display back plate produced by the invention, a general semi-columnar spacer is formed at a desired position, and 4; = : "the mouth of the device is α, and the size of the gap can be controlled. The liquid crystal that is subsequently placed can be effectively played. Compared with the conventional crystal liquid crystal display manufacturing method, the lithography and the etching of the back plate are used to make the position fixed and high, so that the bead-like gap can be avoided in the conventional method. The manufacturing method of the present invention precisely controlled and maintained is based on the LCoS display and the jumper pad providing the internal circuit, because the upper layer of the transparent conductive substrate is processed in the process, so that the conventional method can be reduced in the rate of 'reducing the cost. The manufacturing method of the present invention is such that the semiconductor process is in the columnar spacer in which the twin crystal liquid crystal is fixed, and thus the body distribution is uneven, and the tCoS^ display is manufactured. Further, since the columnar spacer is not simultaneously formed on the back plate The invention does not need to further solder the electrode assembled to the inner circuit board to the process step of the inner circuit board, thereby improving the production example, and all the applications according to the invention should belong to the invention patent Han above are merely exemplary of the present invention, the scope of the patent made uniformly range of modifications and He.

Page 12 1289700 Brief Description of the Drawings Brief Description of the Drawings Fig. 1 is a schematic view showing the structure of the rear stage of the twin crystal liquid crystal display of the present invention. 2A to 2F are schematic views showing a method of fabricating a twin crystal liquid crystal display back sheet of the present invention. DESCRIPTION OF SYMBOLS 10 Crystalline Microdisplay Rear Stage Product Structure 12 Transparent Conductive Substrate 14 Semiconductor Substrate 16 Pixel Array 18 Column Spacer 22 Pad 24 Jumper Pad 26 Mirror Layer 28 Dielectric Layer 30 Jumper Pad Area 31 Lower conductive plate 32 open α 34 plug 36 upper conductive plate 40 pixel array region 42 reflective unit 44 trench 46 first photoresist layer 48 second photoresist layer 50 pad region 51 pad 52 opening

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Claims (1)

1289700 6. Patent application scope 1. A method for producing a liquid crystal on silicon (LCoS) display backplane, the method comprising the steps of: providing a semiconductor substrate; on the semiconductor substrate Forming a reflective mirror layer; selectively etching the mirror layer to define a crossover pad region, a pixel array (pixel ar r ay ) region, and a solder on the semiconductor substrate a bond pad region, wherein the jumper pad region includes a lower conductive plate (b〇tt〇m pad) formed by the mirror layer, the pixel array region including a plurality of mirror layers The reflective unit and the plurality of trenches are formed between the reflective unit, the fresh pad region includes at least one solder pad formed by the mirror layer; and a filling material is filled in the plurality of trenches (gap filling) Depositing a dielectric layer on the jumper pad region, the pixel array region, and the pad region; forming a first photoresist layer on the dielectric layer, a photoresist layer has a plurality of openings above the jumper pad region; performing an engraving process, engraving the dielectric layer through the plurality of openings to form a plurality of dielectric layers in the jumper pad region The jumper pad is filled with holes; θ removes the first photoresist layer; and the conductive material is filled in the plurality of jumper via holes to form a complex Page 14 1289700 6. Applying a plurality of plugs in the patent range; forming an upper conductive plate on the jumper pad region, and electrically connecting the lower conductive plate via the plurality of plugs; forming a first layer on the semiconductor substrate a second photoresist layer, wherein the second photoresist layer defines a plurality of spacers above the dielectric layer of the pixel array region; and the dielectric layer is left in the pixel array region A plurality of spacers are formed in the dielectric layer. 2. The method of claim 1, wherein the mirror layer is a reflective aluminum layer. 3. The method of claim 1, wherein after forming the mirror layer, the method further comprises: forming a reflection enhancement layer (Reflectance Enhancement Passivation layer) on the mirror layer to offset The reflection inhibiting effects produced by the semiconductor substrate. The method of claim 1, wherein after forming the plurality of spacers, the method further comprises: covering the semiconductor substrate with a transparent conductive substrate, and the transparent conductive substrate and the jumper pad region The upper conductive plate is electrically connected. k 5. The method of claim 1, wherein the jumper pad area Page 15 1289700 The conductive plate on the upper surface has a top surface slightly offset from the top surface of the spacer. 6. The method of claim 1, wherein the method simultaneously forms a plurality of spacers in the dielectric layer of the pixel array region, and simultaneously etches a plurality of the dielectric layers in the pad region Open the access pad to the underside. The method of claim 1, wherein when the method forms a plurality of spacers in the dielectric layer of the pixel array region, the plurality of spacers may not be etched in the dielectric layer of the pad region at the same time An opening leads to the underlying pad. 8. A method of fabricating a backplane (LCoS) display backsheet, the method comprising the steps of: providing a semiconductor substrate; forming a mirror layer on the semiconductor substrate; The mirror layer defines a pixel array region on the semiconductor substrate including a plurality of reflective units formed by the mirror layer and a plurality of trenches formed between the reflective units; a gap fi 11 ing is filled with a material in the plurality of trenches; a dielectric I is deposited on the pixel array region to form an aperture above the semiconductor substrate and > the photoresist layer is on the image 1289700. The position of a plurality of spacers is defined above the dielectric layer in the region of the patent application region; and the dielectric layer is named to form a plurality of dielectric layers in the pixel array region. Spacer. 9. The method of claim 8, wherein the mirror layer is a reflective aluminum layer*. The method of claim 8, wherein after forming the mirror layer, the method further comprises: forming a reflection enhancement layer (Reflectance Enhancement Passivation layer) on the mirror layer to offset The reflection suppressing effects produced by the semiconductor substrate. The method of claim 8 wherein the read dielectric layer is composed of hafnium oxide. 1 2. The method of claim 8 wherein the method of inducing a plurality of spacers in the dielectric layer of the pixel array region simultaneously etches a plurality of the dielectric layers in the fresh germanium region Open D, 'two welding 塾.呑海, as in the method of claim 8 wherein the method forms a plurality of spacers in the dielectric layer of the pixel array region, Page 17 — 1289700 Page 18