Forming method of aluminum laminated structure and LCOS (Liquid Crystal On Silicon) device

Abstract

The invention provides a forming method of an aluminum laminated structure and an LCOS device, a first oxide layer, a barrier layer and a sacrificial layer sequentially cover an aluminum metal layer and a first type of protrusions on the aluminum metal layer, the barrier layer is used as a stop layer, the first type of protrusions with partial thickness are removed through grinding, and then the first type of protrusions are removed through etching. In this way, the first type of protrusions are removed step by step through grinding and etching, and the amount of the first type of protrusions removed in each step can be better controlled, so that excessive removal of the first type of protrusions is avoided, and the flatness of the aluminum metal layer is improved. Furthermore, the barrier layer is used as a stop layer for grinding, so that the grinding process can be accurately controlled, excessive removal of the first type of bulges in the grinding process is avoided, a wider process window is provided for the subsequent etching process, and the process control is simpler, more convenient and more accurate. Therefore, the formed reflecting electrode has higher reflectivity, and an LCOS device with better display performance can be obtained.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor manufacturing technology, and in particular to a method for forming an aluminum laminated structure and an LCOS device. Background Art

[0002] In the semiconductor manufacturing process, aluminum (Al) metal is often used to form the corresponding device structure. For example, in the back-side illuminated (BSI) image sensor, aluminum metal is used to form a metal grid structure to reduce the crosstalk between adjacent pixels due to its excellent visible light reflection performance and simple manufacturing process. For another example, in the liquid crystal on silicon (LCOS) display, an aluminum metal layer is usually used as a reflective electrode. The reflective electrode is an important component of the silicon-based liquid crystal display. Its reflectivity has a direct impact on the overall display performance, and the flatness of the aluminum metal layer will directly affect the reflectivity. However, due to the poor thermal stability and mechanical properties of aluminum metal itself, it is very easy to form a hillock defect on the metal surface, which reduces its flatness and thus reduces the performance of the corresponding device structure. Summary of the invention

[0003] The object of the present invention is to provide a method for forming an aluminum stacked structure and an LCOS device to solve the problem in the prior art that the aluminum metal surface has serious hillock-like protrusion defects.

[0004] In order to solve the above technical problems, the present invention provides a method for forming an aluminum laminated structure, the method for forming an aluminum laminated structure comprising:

[0005] Forming an aluminum metal layer, wherein the surface of the aluminum metal layer has a plurality of protrusions, wherein the plurality of protrusions include first-type protrusions, and the height of the first-type protrusions is greater than or equal to a threshold;

[0006] forming a first oxide layer on the aluminum metal layer, wherein the first oxide layer covers the protrusions, and a height of the first oxide layer is less than a height of the first type of protrusions;

[0007] forming a barrier layer on the first oxide layer, wherein the height of the barrier layer is smaller than the height of the first type of protrusions;

[0008] forming a sacrificial layer on the barrier layer, wherein the height of the sacrificial layer is greater than the height of the first type of protrusions;

[0009] Using the barrier layer as a stop layer, grinding the sacrificial layer and the first type of protrusions to remove the sacrificial layer and a portion of the thickness of the first type of protrusions;

[0010] Etching the first type of protrusions to remove the first type of protrusions and expose a portion of the aluminum metal layer; and,

[0011] A second oxide layer is formed covering the aluminum metal layer.

[0012] Optionally, in the method for forming the aluminum stacked structure, after grinding the sacrificial layer and the first type of protrusions and before etching the first type of protrusions, the method for forming the aluminum stacked structure further includes:

[0013] The barrier layer and the first type of protrusions are ground to thin the first type of protrusions and remove all or part of the thickness of the barrier layer.

[0014] Optionally, in the method for forming the aluminum stacked structure, the process temperature for forming the first oxide layer is less than 600°C, and / or the process temperature for forming the second oxide layer is less than 600°C.

[0015] Optionally, in the method for forming the aluminum stacked structure, the material of the barrier layer is silicon nitride and / or silicon oxynitride, and the material of the sacrificial layer is oxide.

[0016] Optionally, in the method for forming the aluminum stacked structure, the thickness of the barrier layer is smaller than the thickness of the first oxide layer and the sacrificial layer, and the thickness of the first oxide layer is smaller than the thickness of the sacrificial layer.

[0017] Optionally, in the method for forming the aluminum laminated structure, the thickness of the first oxide layer is greater than The thickness of the barrier layer is greater than The thickness of the sacrificial layer is greater than

[0018] Optionally, in the method for forming an aluminum stacked structure, the plurality of protrusions further include a second type of protrusions, the height of the second type of protrusions is less than the threshold, and the height of the first oxide layer is greater than the height of the second type of protrusions.

[0019] Optionally, in the method for forming the aluminum stacked structure, the first type of protrusions are exposed by etching with hydrofluoric acid or ammonia.

[0020] Optionally, in the method for forming the aluminum laminated structure, after forming the second oxide layer covering the aluminum metal layer, the method for forming the aluminum laminated structure further comprises:

[0021] The second oxide layer is polished to planarize the second oxide layer.

[0022] The present invention further provides an LCOS device, comprising:

[0023] Silicon substrate;

[0024] an aluminum metal layer located on the silicon substrate, the surface of the aluminum metal layer having a protrusion, the height of the protrusion being less than or equal to a threshold, and the aluminum metal layer serving as a reflective electrode;

[0025] a first oxide layer located on the aluminum metal layer, the first oxide layer covering the protrusion, the height of the first oxide layer being greater than the height of the protrusion, and the first oxide layer having an opening exposing the aluminum metal layer; and

[0026] A second oxide layer fills the opening.

[0027] In the method for forming an aluminum laminated structure and the LCOS device provided by the present invention, the first oxide layer, the barrier layer and the sacrificial layer sequentially cover the aluminum metal layer and the first type of protrusions thereon, the height of the first type of protrusions is greater than or equal to the threshold, the barrier layer is used as a stop layer, the first type of protrusions of a part of the thickness are removed by grinding, and then the first type of protrusions are removed by etching. Here, by removing the first type of protrusions in steps by grinding and etching, the amount of the first type of protrusions removed in each step can be better controlled, thereby avoiding excessive removal of the first type of protrusions, and improving the flatness of the aluminum metal layer. Furthermore, using the barrier layer as a stop layer for grinding, the grinding process can be accurately controlled to avoid excessive removal of the first type of protrusions during the grinding process, and a wider process window is provided for the subsequent etching process, making the process control simpler and more accurate, and further ensuring the flatness of the aluminum metal layer. The reflective electrode thus formed has a higher reflectivity, and accordingly, an LCOS device with better display performance can be obtained. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figures 1 to 5 It is a schematic cross-sectional view of a device structure formed by executing the method for forming an aluminum stacked structure according to an embodiment of the present invention.

[0029] The reference numerals are described as follows:

[0030] 100-aluminum metal layer; 110-protrusion; 110A-first protrusion; 110B-second protrusion; 110C-third protrusion; 120-first oxide layer; 121-opening; 130-barrier layer; 140-sacrificial layer; 150-second oxide layer;

[0031] H1, H2, H3, H4, H5, H6 - height. DETAILED DESCRIPTION

[0032] The following is a further detailed description of the method for forming the aluminum laminated structure and the LCOS device proposed in the present invention in conjunction with the accompanying drawings and specific embodiments. The advantages and features of the present invention will become clearer according to the following description. It should be noted that the accompanying drawings are all in a very simplified form and are not in precise proportions, and are only used to conveniently and clearly assist in explaining the purpose of the embodiments of the present invention.

[0033] The terms used in the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. Unless otherwise defined in the present application document, the technical terms or scientific terms used in the present invention should be the common meaning understood by people with ordinary skills in the field to which the present invention belongs. The words "first", "second" and similar words used in the present specification and claims do not indicate any order, quantity or importance, but are only used to distinguish different components. Similarly, words such as "one" or "one" do not indicate a quantity limit, but indicate that there is at least one. "Multiple" or "several" means two or more. Unless otherwise specified, words such as "upper / upper layer", "lower / lower layer" and the like are only for the convenience of explanation and are not limited to one position or one spatial orientation. Words such as "include" or "comprise" and the like mean that the elements or objects appearing in front of "include" or "comprise" include the elements or objects listed after "include" or "comprise" and their equivalents, and do not exclude other elements or objects. Words such as "connect" or "connected" and the like are not limited to physical or mechanical connections, and can include electrical connections, whether direct or indirect. The singular forms "a", "said" and "the" used in the present specification and the appended claims are also intended to include the plural forms, unless the context clearly indicates otherwise. It should also be understood that the term "and / or" used herein refers to and includes any or all possible combinations of one or more of the associated listed items.

[0034] The core idea of ​​the present invention is to provide a method for forming an aluminum laminated structure and an LCOS device, wherein a first oxide layer, a barrier layer and a sacrificial layer sequentially cover an aluminum metal layer and a first type of protrusion thereon, the height of the first type of protrusion is greater than or equal to a threshold, the barrier layer is used as a stop layer, a portion of the thickness of the first type of protrusion is removed by grinding, and then the first type of protrusion is removed by etching. Here, by removing the first type of protrusion in steps by grinding and etching, the amount of the first type of protrusion removed in each step can be better controlled, thereby avoiding excessive removal of the first type of protrusion and improving the flatness of the aluminum metal layer. Furthermore, by using the barrier layer as a stop layer for grinding, the grinding process can be accurately controlled to avoid excessive removal of the first type of protrusion during the grinding process, and a wider process window is provided for the subsequent etching process, making the process control simpler and more accurate, and further ensuring the flatness of the aluminum metal layer. The reflective electrode thus formed has a higher reflectivity, and accordingly, an LCOS device with better display performance can be obtained.

[0035] For details, please refer to Figures 1 to 5 , which is a schematic cross-sectional view of a device structure formed by executing the method for forming an aluminum stacked structure according to an embodiment of the present invention.

[0036] like Figure 1 As shown, an aluminum metal layer 100 is formed, and the surface of the aluminum metal layer 100 has a plurality of protrusions 110. The aluminum metal layer 100 can be formed on a semiconductor material layer, a conductive layer, or a dielectric material layer, etc., and this application does not limit this. In one embodiment of the present application, the aluminum metal layer 100 is formed on a silicon substrate (not shown in the figure) to serve as a reflective electrode.

[0037] Please continue to refer to Figure 1Here, three protrusions 110 are schematically shown, namely, a first protrusion 110A, a second protrusion 110B, and a third protrusion 110C. Here, the height H1 of the first protrusion 110A is greater than the height H2 of the second protrusion 110B, and the height H2 of the second protrusion 110B is greater than the height H3 of the third protrusion 110C. The heights of the first protrusion 110A and the second protrusion 110B are greater than or equal to a threshold value, and are protrusions of the first type; the height of the third protrusion 110C is less than the threshold value, and is a protrusion of the second type. In the embodiment of the present application, the height H2 of the second protrusion 110B is used as the height of the first type of protrusion; the height H3 of the third protrusion 110C is used as the height of the second type of protrusion. In other embodiments of the present application, the heights of the first and second types of protrusions may also be set separately. For example, a first value between the height H2 of the second protrusion 110B and the height H3 of the third protrusion 110C is set as the height of the first type of protrusion, and a second value between the height H2 of the second protrusion 110B and the height H3 of the third protrusion 110C is set as the height of the second type of protrusion, wherein the first value is greater than the second value.

[0038] Here, the threshold is set according to the tolerance for the hillock-like protrusion defect. When the tolerance is low, that is, when the flatness requirement for the surface of the aluminum metal layer 100 is high, the threshold is small, for example, When the tolerance is high, that is, when the requirement for the flatness of the surface of the aluminum metal layer 100 is low, the threshold is large, for example, In the embodiment of the present application, the aluminum metal layer 100 is used to form a reflective electrode of the LCOS device. In order to improve the reflectivity of the LCOS device, it is necessary to improve the flatness of the aluminum metal layer 100, that is, it is necessary to reduce the protrusions on the aluminum metal layer 100 as much as possible. The threshold value is, for example, or lower, so as to obtain the aluminum metal layer 100 with better flatness.

[0039] In the embodiment of the present application, then, a first oxide layer 120 is formed on the aluminum metal layer 100, and the first oxide layer 120 covers the aluminum metal layer 100 and the protrusions 110, that is, covers the first type of protrusions: the first protrusions 110A and the second protrusions 110B, and covers the second type of protrusions: the third protrusions 110C. The first oxide layer 120 can protect the aluminum metal layer 100 and prevent the aluminum metal layer 100 from being damaged by subsequent processes.

[0040] like Figure 1As shown, the height H4 of the first oxide layer 120 is less than the height of the first type of protrusion (here, the height H2 of the second protrusion 110B). Further, the height H4 of the first oxide layer 120 is also greater than the height of the second type of protrusion (here, the height H3 of the third protrusion 110C).

[0041] In an embodiment of the present application, the first oxide layer 120 is formed by a low-temperature chemical vapor deposition process, and the first oxide layer 120 can protect the aluminum metal layer 100, and avoid forming more protrusions on the surface of the aluminum metal layer 100 in subsequent processes; at the same time, the first oxide layer 120 is formed by a low-temperature process, and it is also possible to avoid the formation of large protrusions with a height exceeding a threshold value on the surface of the aluminum metal layer 100 during the formation of the first oxide layer 120. Among them, the process temperature for forming the first oxide layer 120 is less than 600°C, and further, the process temperature for forming the first oxide layer 120 is between 200°C and 450°C, for example, the process temperature for forming the first oxide layer 120 is 200°C, 280°C, 360°C or 450°C, etc. Specifically, the first oxide layer 120 can be formed by a low-temperature plasma enhanced chemical vapor deposition process (PECVD).

[0042] Specifically, the reaction gas for forming the first oxide layer 120 may be monosilane (SiH4) or tetraethyl orthosilicate (TEOS). Preferably, when monosilane (SiH4) is used to form the first oxide layer 120, the deposition rate is less than or equal to When tetraethyl orthosilicate (TEOS) is used to form the first oxide layer 120, the deposition rate is less than or equal to Thereby, the quality of the first oxide layer 120 formed can be improved, and the aluminum metal layer 100 can be better protected.

[0043] Please continue to refer to Figure 1 , in an embodiment of the present application, then, a barrier layer 130 is formed on the first oxide layer 120. Here, the barrier layer 130 can be used as a stop layer for the subsequent grinding process. The height H5 of the barrier layer 130 is less than the height of the first type of protrusion. Among them, the material of the barrier layer 130 can be silicon nitride and / or silicon oxynitride. The barrier layer 130 can be a single-layer structure or a multi-layer stacked structure. For example, the barrier layer 130 can include a layer of silicon nitride layer or a layer of silicon oxynitride layer. The barrier layer 130 can also include multiple stacked silicon nitride layers and silicon oxynitride layers. In one embodiment of the present application, the barrier layer 130 can also include multiple staggered stacked silicon nitride layers and silicon oxynitride layers, and the thickness of each layer of the silicon nitride layer and / or the silicon oxynitride layer is less than or equal to Therefore, in the subsequent grinding process, the grinding removal amount of the first type of protrusions can be better controlled to avoid excessive removal of the first type of protrusions.

[0044] The function of the barrier layer 130 is that during the chemical mechanical polishing of the silicon nitride layer and / or the silicon nitride oxide layer (i.e., the barrier layer 130 itself), generally speaking, the polishing liquid contains silica sol or other oxide particles, and the chemical composition is usually alkaline or weakly acidic. When the chemical composition is weakly acidic, the first type of protrusions are not only consumed by mechanical force during the mechanical polishing process, but also react with the polishing liquid to grind part of the silicon nitride layer and stop, thereby achieving mechanical force consumption and chemical reaction consumption of the first type of protrusions. Mechanical consumption is easy to control, but chemical reaction consumption is not easy to control. Therefore, a first oxide layer 120 and a barrier layer 130 must be set on the surface of the aluminum layer (the polishing rates of the first oxide layer 120 and the barrier layer 130 are different), and the barrier layer 130 must be used as a polishing stop layer. The barrier layer 130 is used to set a specific thickness so that during the grinding process of the barrier layer 130 (at this time, part of the surface of the first type of protrusion has been exposed), the consumption degree of the first type of protrusion is controlled by controlling the grinding process of the barrier layer 130 (including mechanical force consumption and chemical process consumption). If this layer is not used for precise control, the consumption of the first type of protrusion during the grinding process will be difficult to accurately control (especially the chemical process, which is extremely difficult to control). Therefore, it is necessary to set the barrier layer 130 on the first oxide layer 120. Furthermore, because there is also the first oxide layer 120 at the bottom of the barrier layer 130 (so that the first type of protrusion also has a certain height in the first oxide layer 120), the significance of the existence of the first oxide layer 120 is to serve as a height buffer for the consumption of the first type of protrusion by the chemical process (including the grinding process of the sacrificial layer and / or the grinding process of the barrier layer) to ensure that the consumption in the chemical process is controllable as much as possible.

[0045] Specifically, the barrier layer 130 may be formed by a chemical vapor deposition process, such as a plasma enhanced chemical vapor deposition process (PECVD). Here, since the first oxide layer 120 is formed on the aluminum metal layer 100 to protect the aluminum metal layer 100, the barrier layer 130 has a wider process window, and accordingly, the barrier layer 130 formation process is simpler. The process temperature may be high or low, for example, the process temperature for forming the barrier layer 130 may be 1000°C or 500°C.

[0046] In the embodiment of the present application, a sacrificial layer 140 is then formed on the barrier layer 130. Here, the height H6 of the sacrificial layer 140 is greater than the height of the first type of protrusions. Thus, the first type of protrusions of a certain thickness can be removed by grinding the sacrificial layer 140, so that the first type of protrusions can be better removed and the removal amount of the first type of protrusions can be more accurately controlled. The sacrificial layer 140 is made of oxide.

[0047] Specifically, a chemical vapor deposition process, such as a plasma enhanced chemical vapor deposition process (PECVD) may be used to form the sacrificial layer 140. The process temperature for forming the sacrificial layer 140 may be either high or low.

[0048] In the embodiment of the present application, the first oxide layer 120 can protect the aluminum metal layer 100, and at the same time, control the consumption of the first type of protrusions during the grinding process to avoid over-consumption of the first type of protrusions; the barrier layer 130 can play the role of a grinding stop layer, and at the same time, control the consumption of the first type of protrusions during the grinding process of the sacrificial layer 140 and itself to avoid over-consumption of the first type of protrusions; and the sacrificial layer 140 is mainly used for grinding the sacrificial layer to remove part of the thickness of the first type of protrusions through the grinding process, and it can have a thicker thickness so that the grinding process has more process margins and is convenient for controlling the grinding process. Preferably, the thickness of the barrier layer 130 is less than the thickness of the first oxide layer 120, and at the same time, it is also less than the thickness of the sacrificial layer 140, and the thickness of the first oxide layer 120 is less than the thickness of the sacrificial layer 140.

[0049] Among them, during the chemical mechanical polishing of the sacrificial layer 140, the first type of protrusions usually have mechanical force consumption and chemical reaction consumption. The mechanical consumption is easy to control, but the chemical reaction consumption is not easy to control. Therefore, in the embodiment of the present application, a first oxide layer 120 and a barrier layer 130 are set on the surface of the aluminum metal layer 100 (the polishing rates of the first oxide layer 120 and the barrier layer 130 are different). The barrier layer 130 serves as a polishing stop layer, which can control the consumption of the first type of protrusions. At the same time, the first oxide layer 120 can play a highly buffering role to avoid excessive consumption of the first type of protrusions.

[0050] In the embodiment of the present application, the thickness of the first oxide layer 120 is greater than The thickness of the barrier layer 130 is greater than The thickness of the sacrificial layer 140 is greater than This also enables better control of the film formation and film quality.

[0051] Then, if Figure 2As shown, the sacrificial layer 140 and the first type of protrusions are ground with the barrier layer 130 as a stop layer to remove the sacrificial layer 140 and a portion of the thickness of the first type of protrusions. In the embodiment of the present application, the first type of protrusions of a portion of the thickness are first removed by a grinding process, that is, the amount of the first type of protrusions removed in one process step is controlled to avoid a reduction in the process control accuracy due to an excessive amount of the first type of protrusions removed, that is, the accuracy of the process control is improved, so as to facilitate the formation of a flat aluminum metal layer. Accordingly, the time of each process step can also be controlled, and here, it can also be avoided that the first type of protrusions are excessively removed due to the long residence time of the grinding liquid.

[0052] Here, the remaining thickness of the first type of protrusions is exposed, that is, the first protrusions 110A and the second protrusions 110B are exposed. In the embodiment of the present application, the barrier layer 130 is used as a grinding stop layer to simplify the process, accurately control the stop of the grinding process, accurately control the removal amount of the grinding process, avoid excessive removal of the first type of protrusions during the grinding process, and thus obtain a flatter aluminum metal layer 100.

[0053] In the embodiment of the present application, the barrier layer 130 is further ground, whereby the first oxide layer 120 is exposed, that is, the barrier layer 130 of the entire thickness is ground and removed; at the same time, part of the first protrusion 110A and the second protrusion 110B is further ground and removed. That is, by further grinding the process to reduce the amount of the first protrusion 110A and the second protrusion 110B removed in each process, the removal of the first type of protrusions can be more accurately controlled. Among them, the grinding liquid selected for grinding the barrier layer 130 can be different from the grinding liquid selected for grinding the sacrificial layer 140, so as to better control the removal of the sacrificial layer 140 and the barrier layer 130. In other embodiments of the present application, the barrier layer 130 of a part of its thickness can also be ground and removed, and the barrier layer 130 of a part of its thickness can be retained. For example, the remaining barrier layer 130 can be used as a protective layer for a reflective electrode, etc.

[0054] That is, the barrier layer 130 is used to achieve precise control of the consumption of the first type of protrusions to avoid over-consumption of the first type of protrusions. Furthermore, the first oxide layer 120 thereunder is used as a height buffer for the first type of protrusions in the grinding process to increase the process margin, simplify process control, and ultimately improve the flatness of the aluminum metal layer.

[0055] Please refer to Figure 3Then, the exposed first type of protrusions are etched to remove the first type of protrusions and expose part of the aluminum metal layer 100, that is, the first protrusions 110A and the second protrusions 110B are etched to remove, and an opening 121 is formed in the first oxide layer 120 to expose part of the aluminum metal layer 100. In the embodiment of the present application, since a part of the thickness of the first type of protrusions is removed by the grinding process, the thickness of the first type of protrusions removed by the etching process is relatively small, so that the removal amount of the first type of protrusions can be well controlled, and the etching solution can be prevented from staying for too long and excessively removing the first type of protrusions, so that a flatter aluminum metal layer 100 can be obtained. After the first type of protrusions are removed by the etching process, the surface of the corresponding aluminum metal layer 100 can be flat, slightly protruding, or slightly concave, wherein the remaining protrusions or the formed concave are less than the threshold, that is, a flattened aluminum metal layer 100 can be formed, and the performance of the corresponding device can be improved, and here the reflectivity of the LCOS device can be improved.

[0056] In the embodiment of the present application, the first type of protrusions exposed can be etched with hydrofluoric acid or ammonia water to better control the removal speed of the first type of protrusions, so that the surface of the aluminum metal layer 100 is smoother.

[0057] Please refer to Figure 4 In the embodiment of the present application, then, a second oxide layer 150 is formed to cover the aluminum metal layer 100. Preferably, the second oxide layer 150 is formed by a low temperature process to protect the flatness of the aluminum metal layer 100. The process temperature for forming the second oxide layer 150 is less than 600°C. Further, the process temperature for forming the second oxide layer 150 is between 200°C and 450°C. For example, the process temperature for forming the second oxide layer 150 is 200°C, 280°C, 360°C or 450°C. Specifically, the second oxide layer 150 can be formed by a low temperature plasma enhanced chemical vapor deposition process (PECVD).

[0058] Furthermore, the second oxide layer 150 also covers the first oxide layer 120. The thickness of the second oxide layer 150 is preferably greater than This also enables better control of the film formation and film quality.

[0059] like Figure 5 As shown, in the embodiment of the present application, further, the second oxide layer 150 is ground to planarize the second oxide layer 150 .

[0060] like Figure 1 and Figure 5As shown, in an embodiment of the present application, a barrier layer 130 is formed on the first oxide layer 120, a sacrificial layer 140 is formed on the barrier layer 130, the sacrificial layer 140 and the first type of protrusions are ground to remove a portion of the thickness of the first type of protrusions, and the exposed first type of protrusions are etched to remove. By removing the first type of protrusions in steps by grinding and etching, the amount of the first type of protrusions removed in each step and the process time can be better controlled, thereby avoiding excessive removal of the first type of protrusions and improving the flatness of the aluminum metal layer.

[0061] Accordingly, the present application also provides an aluminum laminate structure, such as Figure 4 As shown, the aluminum stacked structure includes: an aluminum metal layer 100, the surface of the aluminum metal layer 100 has a protrusion 110, the height of the protrusion 110 is less than or equal to a threshold, that is, it is a second type of protrusion; a first oxide layer 120 located on the aluminum metal layer 100, the first oxide layer 120 covers the protrusion 110, the height H4 of the first oxide layer 120 is greater than the height H3 of the protrusion 110, the first oxide layer 120 has an opening 121 exposing the aluminum metal layer 100; and a second oxide layer 150 filling the opening 121.

[0062] In the embodiment of the present application, the aluminum metal layer 100 is used to form a reflective electrode of the LCOS device. Specifically, the LCOS device includes a silicon substrate (not shown in the figure) and the aluminum metal layer 100 located on the silicon substrate. The aluminum metal layer 100 is covered with the first oxide layer 120 and the second oxide layer 150, and the first oxide layer 120 and the second oxide layer 150 can be used as a protective layer for the aluminum metal layer 100. In other embodiments of the present application, the aluminum metal layer 100 can be further etched to form a reflective electrode. Through the first oxide layer 120 and the second oxide layer 150, the barrier layer 130 can be further included to protect the aluminum metal layer 100, thereby improving the reliability of subsequent processes. In the embodiment of the present application, the surface of the aluminum metal layer 100 is flat, so that the reflectivity of the LCOS device can be improved, and an LCOS device with better display performance can be obtained.

[0063] The first oxide layer 120 and the second oxide layer 150 may be formed by a low temperature process, wherein the process temperature is less than 600° C., preferably, the process temperature is between 200° C. and 450° C., so as to further improve the flatness of the aluminum metal layer 100 .

[0064] From the above, it can be seen that in the method for forming an aluminum stacked structure and the LCOS device provided by the present invention, the first oxide layer, the barrier layer and the sacrificial layer sequentially cover the aluminum metal layer and the first type of protrusions thereon, the height of the first type of protrusions is greater than or equal to a threshold value, the barrier layer is used as a stop layer, a portion of the thickness of the first type of protrusions is removed by grinding, and then the first type of protrusions are removed by etching. Here, by removing the first type of protrusions in steps by grinding and etching, the amount of the first type of protrusions removed in each step can be better controlled, thereby avoiding excessive removal of the first type of protrusions and improving the flatness of the aluminum metal layer. Furthermore, by using the barrier layer as a stop layer for grinding, the grinding process can be accurately controlled to avoid excessive removal of the first type of protrusions during the grinding process, and a wider process window is provided for the subsequent etching process, making the process control simpler and more accurate, and further ensuring the flatness of the aluminum metal layer. The reflective electrode thus formed has a higher reflectivity, and accordingly, an LCOS device with better display performance can be obtained.

[0065] In the present application, references to "one embodiment" or "some embodiments" mean that features, structures, or characteristics described in conjunction with the embodiment are included in at least one embodiment, at least some embodiments, of the present application. Therefore, the appearance of the phrases "in one embodiment" or "in some embodiments" in various places of the present application does not necessarily refer to the same or the same embodiments. In addition, in one or more embodiments, features, structures, or characteristics may be combined in any suitable combination and / or sub-combination.

[0066] Although some specific embodiments of the present application have been described in detail by way of example, it will be appreciated by those skilled in the art that the above examples are for illustration only and are not intended to limit the scope of the present application. The various embodiments of the present application may be combined in any manner without departing from the spirit and scope of the present application. It will also be appreciated by those skilled in the art that various modifications may be made to the embodiments without departing from the scope and spirit of the present application. The scope of the present application is defined by the appended claims.

Claims

1. A method for forming an aluminum laminate structure, characterized in that: The method for forming the aluminum laminated structure comprises: Forming an aluminum metal layer, wherein the surface of the aluminum metal layer has a plurality of protrusions, wherein the plurality of protrusions include first-type protrusions, and the height of the first-type protrusions is greater than or equal to a threshold; forming a first oxide layer on the aluminum metal layer, wherein the first oxide layer covers the protrusions, and a height of the first oxide layer is less than a height of the first type of protrusions; forming a barrier layer on the first oxide layer, wherein the height of the barrier layer is smaller than the height of the first type of protrusions; forming a sacrificial layer on the barrier layer, wherein the height of the sacrificial layer is greater than the height of the first type of protrusions; Using the barrier layer as a stop layer, grinding the sacrificial layer and the first type of protrusions to remove the sacrificial layer and a portion of the thickness of the first type of protrusions; Etching the first type of protrusions to remove the first type of protrusions and expose a portion of the aluminum metal layer; and, A second oxide layer is formed covering the aluminum metal layer.

2. The method for forming an aluminum laminate structure according to claim 1, wherein: After grinding the sacrificial layer and the first type of protrusions and before etching the first type of protrusions, the method for forming the aluminum stacked structure further includes: The barrier layer and the first type of protrusions are ground to thin the first type of protrusions and remove all or part of the thickness of the barrier layer.

3. The method for forming an aluminum laminated structure according to claim 1, wherein: The process temperature for forming the first oxide layer is less than 600° C., and / or the process temperature for forming the second oxide layer is less than 600° C.

4. The method for forming an aluminum laminated structure according to any one of claims 1 to 3, characterized in that: The material of the barrier layer is silicon nitride and / or silicon oxynitride, and the material of the sacrificial layer is oxide.

5. The method for forming an aluminum laminated structure according to any one of claims 1 to 3, characterized in that: The thickness of the blocking layer is smaller than the thickness of the first oxide layer and the sacrificial layer, and the thickness of the first oxide layer is smaller than the thickness of the sacrificial layer.

6. The method for forming an aluminum laminated structure according to any one of claims 1 to 3, characterized in that: The thickness of the first oxide layer is greater than The thickness of the barrier layer is greater than The thickness of the sacrificial layer is greater than 7. The method for forming an aluminum laminated structure according to any one of claims 1 to 4, characterized in that: The plurality of protrusions further include a second type of protrusions, the height of the second type of protrusions is less than the threshold, and the height of the first oxide layer is greater than the height of the second type of protrusions.

8. The method for forming an aluminum laminated structure according to any one of claims 1 to 4, characterized in that: The first type of protrusions are etched by hydrofluoric acid or ammonia water.

9. The method for forming an aluminum laminated structure according to any one of claims 1 to 4, characterized in that: After forming a second oxide layer covering the aluminum metal layer, the method for forming the aluminum stacked structure further includes: The second oxide layer is polished to planarize the second oxide layer.

10. An LCOS device, characterized in that: The LCOS device comprises: Silicon substrate; an aluminum metal layer located on the silicon substrate, the surface of the aluminum metal layer having a protrusion, the height of the protrusion being less than or equal to a threshold, and the aluminum metal layer serving as a reflective electrode; a first oxide layer located on the aluminum metal layer, the first oxide layer covering the protrusion, the height of the first oxide layer being greater than the height of the protrusion, and the first oxide layer having an opening exposing the aluminum metal layer; and A second oxide layer fills the opening.

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