Reflective liquid crystal display element comprising first and second alignment marks that are opposed to each other and third and fourth alignment marks disposed as reference marks
10488715 ยท 2019-11-26
Assignee
Inventors
Cpc classification
G03F9/7084
PHYSICS
International classification
Abstract
According to an embodiment, a reflective liquid crystal display element includes a first substrate, an electronic circuit and an insulating layer including the electronic circuit formed on a surface of the first substrate, a plurality of reflection metal electrodes formed on a surface of the insulating layer, a plurality of spacers, a second substrate opposed to the first substrate with the plurality of spacers interposed therebetween, a plurality of color filters formed on a surface of a second substrate, the plurality of color filters corresponding to the plurality of reflection metal electrodes, a coating layer formed so as to cover the plurality of color filters, a transparent electrode formed on a surface of the coating layer, and a liquid crystal formed in a spatial area between the first and second substrates.
Claims
1. A reflective liquid crystal display element comprising: a first substrate; an electronic circuit and an insulating layer including the electronic circuit formed on a surface of the first substrate; a plurality of reflection metal electrodes formed on a surface of the insulating layer; a plurality of spacers; a second substrate opposed to the first substrate with the plurality of spacers interposed therebetween; a liquid crystal formed in a spatial area between the second substrate and the plurality of reflection metal electrodes; a plurality of color filters formed between the second substrate and the liquid crystal, the plurality of color filters corresponding to the plurality of reflection metal electrodes; a coating layer formed so as to cover the plurality of color filters; a transparent electrode formed on a surface of the coating layer; a first alignment mark formed together with the plurality of reflection metal electrodes on the surface of the insulating layer; a second alignment mark formed together with the plurality of color filters on the surface of the second substrate; a third alignment mark formed on the surface of the first substrate in a different layer than the first alignment mark, the third alignment mark to be a reference when the plurality of reflection metal electrodes and the first alignment mark are formed; and a fourth alignment mark formed on the surface of the second substrate to be a reference when the plurality of color filters and the second alignment mark are formed, wherein the first and second substrates are disposed so that the first and second alignment marks are opposed to each other, and both the third and fourth alignment marks are disposed at places different from places where the first and second alignment marks are disposed.
2. The reflective liquid crystal display element according to claim 1, wherein the first alignment mark is formed of two marks, the second alignment mark is formed of two marks, and the first and second substrates are disposed so that the two marks of the first alignment mark are opposed to the two marks of the second alignment mark, respectively.
3. The reflective liquid crystal display element according to claim 1, wherein at least one of the plurality of spacers is a conductive spacer configured to electrically connect the electronic circuit with the transparent electrode, the reflective liquid crystal display element further comprises an electrode configured to supply electric power to the conductive spacer, and the electrode is formed by using the third alignment mark as a reference point.
4. The reflective liquid crystal display element according to claim 1, wherein the transparent electrode is formed so as to extend into an area where the liquid crystal is not formed.
5. The reflective liquid crystal display element according to claim 1, further comprising a sealing material configured to seal the liquid crystal together with the first and second substrates between the first and second substrates, wherein the plurality of spacers are disposed inside the sealing material.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
(1) The above and other aspects, advantages and features will be more apparent from the following description of certain embodiments taken in conjunction with the accompanying drawings, in which:
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DETAILED DESCRIPTION
First Embodiment
(13) Embodiments according to the present disclosure are explained hereinafter with reference to the drawings.
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(16) As shown in
(17) An electronic circuit composed of the plurality of transistors 119 and 120, and the metal lines 116, the insulating layer 115 including the electronic circuit, and the alignment mark 117 are formed on the silicon substrate 121. Note that places on the silicon substrate 121 where respective components are formed are determined by using the place where the alignment mark 117 is formed as a reference place. Although a case in which the silicon substrate 121 is provided is explained in this embodiment, a glass substrate may be used in place of the silicon substrate 121.
(18) Further, on the insulating layer 115, the plurality of reflection metal electrodes 112 and the bonding alignment mark 111 are formed in an internal area of the chip (i.e., an area where the liquid crystal 113 is formed). Further, the electrode 110 is formed in an outer peripheral area of the chip (i.e., an area where the sealing material 108 is formed). Referring to
(19) Further, on the insulating layer 115, the sealing material 108 is formed in the outer peripheral area of the chip. Referring to
(20) The glass substrate 101 is opposed to the silicon substrate 121 with the plurality of spacers interposed therebetween. The alignment mark 118 is formed on the glass substrate 101. Note that places on the glass substrate 101 where respective components are formed are determined by using the place where the alignment mark 118 is formed as a reference place.
(21) Further, on the glass substrate 101, the plurality of color filters 104 to 106 corresponding to the plurality of reflection metal electrodes 112 and the bonding alignment mark 103 are formed in the internal area of the chip (i.e., the area where the liquid crystal 113 is formed). Referring to
(22) Further, the coating layer 102 is formed so as to cover the plurality of color filters 104 to 106. The coating layer 102 flattens a surface of the glass substrate 101. Further, the transparent electrode 107 is formed on a surface of the coating layer 102.
(23) The liquid crystal 113 is sealed (i.e., hermitically contained) in a spatial area surrounded by the silicon substrate 121, the glass substrate 101, and the sealing material 108.
(24) Note that the conductive spacers 109 are in contact with an end of the transparent electrode 107 as well as being in contact with the electrode 110. In this way, for example, electric power that is output when the transistor 120 is turned on is supplied to the transparent electrode 107 through the electrode 110 and the conductive spacers 109 and, as a result, the liquid crystal 113 is driven.
(25) In the reflective liquid crystal display element 100, external light is reflected on the reflection metal electrodes 112 and passes through the liquid crystal 113. Then, after being colored by the color filters 104 to 106, the colored light is displayed on a monitor as an image.
(26) (Method for Manufacturing Reflective Liquid Crystal Display Element)
(27) Next, a method for manufacturing a reflective liquid crystal display element according to this embodiment is explained with reference to
(28) Firstly, an electronic circuit for driving a liquid crystal is formed on a silicon substrate 121 (step S101 in
(29) As shown in
(30) After the formation of the alignment mark 117, a plurality of transistors 119 and a transistor 120 are formed in the same layer that the alignment mark 117 is formed in. Note that the plurality of transistors 119 are transistors for performing switching as to whether electric power is supplied to the reflection metal electrodes 112 or not. Further, the transistor 120 is a transistor for performing switching as to whether electric power is supplied to the electrode 110 or not.
(31) After that, a plurality of metal lines 116 are formed in a plurality of wiring layers located above the layer in which the transistors are formed in such a manner that an insulating layer 115 is interposed between the wiring layers. After that, in an uppermost layer (located on a surface of the insulating layer 115), an electrode 110 is formed in an outer peripheral area of the chip (i.e., an area where the sealing material 108 is formed) and a plurality of reflection metal electrodes 112 and a bonding alignment mark 111 are formed in an internal area of the chip (i.e., an area where the liquid crystal 113 is formed). In this way, an electronic circuit is formed on the silicon substrate 121.
(32) Note that the bonding alignment mark 111 is used to align the silicon substrate 121 with the glass substrate 101 when they are bonded together. Referring to
(33) Next, color filters are formed on the glass substrate 101 (step S102 in
(34) As shown in
(35) After the formation of the alignment mark 118, color filters 104 to 106 for three colors, i.e., for green, red and blue, respectively, are formed one by one on a surface of the glass substrate 101. Further, a bonding alignment mark 103 is also formed.
(36) Note that the bonding alignment mark 103 is used to align the silicon substrate 121 with the glass substrate 101 when they are bonded together. Referring to
(37) After that, a coating layer 102 is formed over the entire surface of the glass substrate 101 so as to cover the color filters 104 to 106 and the bonding alignment mark 103. As a result, the surface of the glass substrate 101 is flattened.
(38) After that, a transparent electrode 107 is formed on a surface of the coating layer 102. More specifically, after the transparent electrode 107 is formed on the entire surface of the coating layer 102, an outer peripheral end part of the transparent electrode 107 is removed by etching. As a result, the transparent electrode 107 is formed into a rectangular shape one size smaller than the chip in a plan view (see
(39) Next, the silicon substrate 121 and the glass substrate 101 are bonded together (step S103 in
(40) As shown in
(41) After that, the silicon substrate 121 and the glass substrate 101 are bonded together in such a manner that the bonding alignment marks 111 and 103 are opposed to each other. In other words, the silicon substrate 121 and the glass substrate 101 are bonded together so that the positions of the bonding alignment marks 111 and 103 coincide with each other in a plan view.
(42) It should be noted that the bonding alignment mark 111 is formed in an uppermost layer of the silicon substrate 121 (more specifically, it is formed on a surface of the insulating layer 115 formed on the silicon substrate 121). In this way, it is possible to adjust the positional relation between the silicon substrate 121 and the glass substrate 101 in a state where the bonding alignment marks 111 and 103 are located close to each other and thereby to accurately arrange the silicon substrate 121 and the glass substrate 101 so that they are opposed to each other.
(43) After that, the sealing material 108 is cured by irradiating it with UV (ultraviolet) rays in a state where the silicon substrate 121 and the glass substrate 101 are bonded together. As a result, the silicon substrate 121 and the glass substrate 101 are joined together. Note that in this state, the conductive spacers 109 are in contact with an end of the transparent electrode 107 as well as being in contact with the electrode 110. In this way, electric power that is output when the transistor 120 is turned on is supplied to the transparent electrode 107 through the electrode 110 and the conductive spacers 109.
(44) Next, a liquid crystal 113 is injected (step S104 in
(45) Through the above-described processes, a reflective liquid crystal display element 100 according to this embodiment as shown in
(46) As described above, the reflective liquid crystal display element 100 and its manufacturing method according to this embodiment make it possible to reduce a gap (a distance) between the transparent electrode 107 and the reflection metal electrodes 112 compared to the gap in the reflective liquid crystal display element in which color filters are formed in a layer located above the reflection metal electrodes 112. As a result, since the reflective liquid crystal display element 100 and its manufacturing method according to this embodiment make it possible to drive the liquid crystal 113 with a low voltage and hence to prevent an increase in the power consumption. That is, the reflective liquid crystal display element 100 and its manufacturing method according to this embodiment can improve the quality of the element.
(47) Further, in the reflective liquid crystal display element 100 and its manufacturing method according to this embodiment, the plurality of spacers are disposed inside the sealing material 108, which is disposed along the outer periphery of the chip, and hence are disposed in a place different from the place where the bonding alignment marks 103 and 111 are disposed in a plan view. Therefore, in the reflective liquid crystal display element 100 and its manufacturing method according to this embodiment, it is possible to adjust the positional relation between the silicon substrate 121 and the glass substrate 101 by using the bonding alignment marks 111 and 103 without obstructing the field of view due to the presence of the plurality of spacers.
(48) Further, in the reflective liquid crystal display element 100 and its manufacturing method according to this embodiment, the end of the transparent electrode 107 is not confined within the internal area of the chip (i.e., the area where the liquid crystal 113 is formed) but extends into the outer peripheral area of the chip (i.e., the area where the sealing material 108 is formed). Therefore, the liquid crystal 113 is not affected by the electric field that is concentrated at the end of the transparent electrode 107.
(49) Further, in the reflective liquid crystal display element 100 and its manufacturing method according to this embodiment, electric power that is output when the transistor 120 is turned on is supplied to the transparent electrode 107 through the electrode 110 and the conductive spacers 109 disposed in the chip. Therefore, no power supply path such as a wiring line is formed outside the chip. Consequently, in the reflective liquid crystal display element 100 and its manufacturing method according to this embodiment, it is possible to prevent a failure caused by a broken wire or the like.
(50) Further, in the reflective liquid crystal display element 100 and its manufacturing method according to this embodiment, the bonding alignment mark 111 as well as the reflection metal electrodes 112 are formed in the uppermost layer of the silicon substrate 121 (more specifically, on the surface of the insulating layer 115 formed on the silicon substrate 121). As a result, in the reflective liquid crystal display element 100 and its manufacturing method according to this embodiment, it is possible to adjust the positional relation between the silicon substrate 121 and the glass substrate 101 in a state where the bonding alignment marks 111 and 103 are located close to each other and thereby to accurately arrange the silicon substrate 121 and the glass substrate 101 so that they are opposed to each other.
(51) Further, in the reflective liquid crystal display element 100 and its manufacturing method according to this embodiment, on the silicon substrate 121, two bonding alignment marks 111 are arranged on a diagonal line of the chip in a plan view. Further, on the glass substrate 101, two bonding alignment marks 103 are arranged on the diagonal line of the chip in a plan view. Therefore, it is also possible to prevent or reduce a positional deviation in a rotational direction between the silicon substrate 121 and the glass substrate 101 when they are opposed to each other.
Second Embodiment
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(53) Firstly, as shown in
(54) Note that the silicon substrate 121 and the glass substrate 101 are disposed so that the bonding alignment marks 111 and 103 are opposed to each other. In other words, the silicon substrate 121 and the glass substrate 101 are disposed so that a deviation between the bonding alignment marks 111 and 103 is within a range of permissible values (e.g., within a range of permissible values in the order of several micrometers) in a plan view.
(55) After that, a fixing member 12 of the manufacturing apparatus 1 is placed above the glass substrate 101. In this way, the silicon substrate 121, the sealing material 108, and the glass substrate 101 are sandwiched by the stage 11 and the fixing member 12. Note that in this state, a height of the stage 11 is h0 and a height of a tip of a stopper 13 is set to h1 (h1>h0).
(56) For example, a thickness of the sealing material 108 is 20 m to several tens of micrometers before it is compressed and its thickness decreases to several micrometers after the compression is completed.
(57) After that, as shown in
(58) In this process, during the movement of the stage 11 from the height h0 to the height h1 (i.e., during the compression process), when a deviation between the positions of the bonding alignment marks 111 and 103 in a plan view is not larger than a permissible value (a predetermined value), the compression is continued. On the other hand, when the deviation between the positions of the bonding alignment marks 111 and 103 in a plan view has exceeded the permissible value, the compression is stopped. Then, while maintaining the stage 11 at the height at the time just before the compression is stopped, one of the positions of the silicon substrate 121 and the glass substrate 101 is adjusted so that the positional deviation becomes equal to or smaller than the permissible value. After that, the compression is restarted and the stage 11 is moved to the height h1.
(59) After that, as shown in
(60) In this process, during the movement of the stage 11 from the height h1 to the height h2 (i.e., during the compression process), when the deviation between the positions of the bonding alignment marks 111 and 103 in a plan view is not larger than the permissible value, the compression is continued. On the other hand, when the deviation between the positions of the bonding alignment marks 111 and 103 in a plan view has exceeded the permissible value, the compression is stopped. Then, while maintaining the stage 11 at the height at the time just before the compression is stopped, one of the positions of the silicon substrate 121 and the glass substrate 101 is adjusted so that the positional deviation becomes equal to or smaller than the permissible value. After that, the compression is restarted and the stage 11 is moved to the height h2.
(61) After that, as shown in
(62) In this process, during the upward movement of the stage 11 from the height h2 (i.e., during the compression process), when the deviation between the positions of the bonding alignment marks 111 and 103 in a plan view is not larger than the permissible value, the compression is continued. On the other hand, when the deviation between the positions of the bonding alignment marks 111 and 103 in a plan view has exceeded the permissible value, the compression is stopped. Then, one of the positions of the silicon substrate 121 and the glass substrate 101 is adjusted so that the positional deviation becomes equal to or smaller than the permissible value. After that, the compression is restarted and the stage 11 is moved until the gap between the silicon substrate 121 and the glass substrate 101 becomes the desired value. After that, a final adjustment for reducing the positional deviation is performed and the sealing material 108 is cured.
(63) As described above, in the manufacturing method for a reflective liquid crystal display element according to this embodiment, during the compression process for the silicon substrate and the glass substrate, it is determined whether or not the deviation between the position of the alignment mark formed in the silicon substrate and the position of the alignment mark formed in the glass substrate is within a permissible range. Then, when the deviation is not within the permissible range, the compression is stopped. Further, after the position is adjusted so that the deviation falls within the permissible range, the compression is restarted. In this way, in the manufacturing method for a reflective liquid crystal display element according to this embodiment, it is possible to accurately arrange the silicon substrate and the glass substrate so that they are opposed to each other. That is, in the manufacturing method for a reflective liquid crystal display element according to this embodiment, it is possible to improve the quality of the reflective liquid crystal display element.
(64) Note that in the case of a manufacturing method for a reflective liquid crystal display element in which an adjustment for reducing a positional deviation is performed only before and after the compression, there is a possibility that the positional deviation could become very large after the completion is completed. In such a case, there is a possibility that, for example, the reflection metal electrodes on the silicon substrate and/or the transparent electrode on the glass substrate could be damaged by the plurality of spherical spacers disposed inside the sealing material because the adjustment for reducing the positional deviation needs to be performed in a state where a high pressure is applied. Further, there is a possibility that the sealing material could expand into an unintended area. Further, there is a possibility that the gap between the silicon substrate and the glass substrate could become nonuniform.
(65) In contrast to this, in the case of the manufacturing method for a reflective liquid crystal display element according to this embodiment, before the compression is completed (more preferably, during the compression process), it is determined whether or not the deviation between the position of the alignment mark formed in the silicon substrate and the position of the alignment mark formed in the glass substrate is within a permissible range. Then, if necessary, the position is adjusted for reducing the deviation. In this way, it is possible to adjust the position for reducing the deviation in a state where a pressure that is smaller than the finally-applied pressure is applied. Further, it is possible to reduce the necessary adjustment for reducing the deviation as much as possible. Therefore, for example, it is possible to prevent the reflection metal electrodes on the silicon substrate and the transparent electrode on the glass substrate from being damaged by the plurality of spherical spacers disposed inside the sealing material. Further, it is possible to prevent the sealing material from expanding into an unintended area. Further, it is possible to make the gap between the silicon substrate and the glass substrate uniform.
(66) Although an example case in which the compression is performed in three divided stages is explained in this embodiment, the present disclosure is not limited to this example. That is, the compression process may be divided into an arbitrary number of stages. Further, an example case in which it is determined whether or not the positional deviation is within a permissible range during the compression process is explained in this embodiment, the present disclosure is not limited to this example. That is, it may be determined whether or not the positional deviation is within a permissible range after the completion of each stage of the compression.
(67) As described above, the reflective liquid crystal display element and its manufacturing method according to the above-described first embodiment make it possible to reduce a gap (a distance) between the transparent electrode 107 and the reflection metal electrodes 112 compared to the gap in the reflective liquid crystal display element in which color filters are formed in a layer located above the reflection metal electrodes 112. As a result, since the reflective liquid crystal display element and its manufacturing method according to the above-described first embodiment make it possible to drive the liquid crystal 113 with a low voltage and hence to prevent an increase in the power consumption. In addition to the above-described other advantageous effects, the reflective liquid crystal display element and its manufacturing method according to the above-described first embodiment can improve the quality of the reflective liquid crystal display element.
(68) Further, in the manufacturing method for a reflective liquid crystal display element according to the above-described second embodiment, during the compression process for the silicon substrate and the glass substrate, it is determined whether or not the deviation between the position of the alignment mark formed in the silicon substrate and the position of the alignment mark formed in the glass substrate is within a permissible range. Then, when the deviation is not within the permissible range, the compression is stopped. Further, after the position is adjusted so that the deviation falls within the permissible range, the compression is restarted. In this way, in the manufacturing method for a reflective liquid crystal display element according to the above-described second embodiment, it is possible to accurately arrange the silicon substrate and the glass substrate so that they are opposed to each other. That is, in the manufacturing method for a reflective liquid crystal display element according to the above-described second embodiment, it is possible to improve the quality of the reflective liquid crystal display element.
(69) Note that the present disclosure is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present disclosure.
(70) The first and second embodiments can be combined as desirable by one of ordinary skill in the art.
(71) While the invention has been described in terms of several embodiments, those skilled in the art will recognize that the invention can be practiced with various modifications within the spirit and scope of the appended claims and the invention is not limited to the examples described above.
(72) Further, the scope of the claims is not limited by the embodiments described above.
(73) Furthermore, it is noted that, Applicant's intent is to encompass equivalents of all claim elements, even if amended later during prosecution.