A method for manufacturing an LCOS device

Abstract

The application provides a manufacturing method of an LCOS device. Before a metal reflecting layer is deposited, a height difference is generated by cutting the first dielectric layer above a cutting path area and the first dielectric layer above a pixel area, so that the deposited metal reflecting layer generates a height difference. After chemical mechanical grinding is performed on the second dielectric layer, the metal reflecting layer above the cutting path area is exposed. The metal reflecting layer above the cutting path area is removed by cleaning, so that the first pattern serving as a photolithography alignment mark can be normally recognized by a photolithography machine, and subsequent process steps such as photolithography and etching can be performed.

Description

Technical Field

[0001] This invention belongs to the field of liquid crystal technology and relates to a method for manufacturing an LCOS device. Background Technology

[0002] LCOS (Liquid Crystal on Silicon) devices are special chips with optical properties. Their wafer top layer requires a highly reflective metal film to form reflective pixels. This highly reflective metal film presents a challenge in pattern alignment during photolithography. Due to the high reflectivity of the metal film, the alignment marks located beneath it are difficult for the photolithography machine to recognize, increasing the difficulty of pattern overlay in the photolithography process.

[0003] In existing technologies, there are two methods to solve the problem of pattern alignment difficulty in high-reflectivity metal films. The first method is to form a relatively deep alignment pattern on the previous substrate. After the high-reflectivity metal film is deposited, there is a significant height difference above the alignment pattern. The lithography machine can use this height difference to identify the previous pattern and achieve pattern alignment. However, due to the height difference above the alignment pattern, some by-products and defects generated during the process will remain, affecting the final product yield. The second method is to add a low-precision photomask. After the high-reflectivity metal film is deposited, an additional lithography and etching step is added. The high-reflectivity metal film above the alignment pattern is removed first, and a window is opened to expose the complete alignment pattern below. This can achieve a better alignment effect during the second lithography. However, the additional lithography and etching steps increase the cost.

[0004] Therefore, how to provide a method for fabricating LCOS devices, improve the alignment accuracy of high-reflectivity metal film patterns, increase product yield, and reduce costs has become a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0005] In view of the shortcomings of the prior art described above, the purpose of this invention is to provide a method for manufacturing an LCOS device to solve the pattern alignment problem caused by the opacity of high reflectivity metal film layers in the prior art.

[0006] To achieve the above and other related objectives, the present invention provides a method for fabricating an LCOS device, comprising the following steps:

[0007] A substrate is provided, the substrate including a dicing area and a pixel area, a first pattern is formed in the dicing area, a second pattern is formed in the pixel area, the pattern density of the second pattern is greater than the pattern density of the first pattern, and the first pattern serves as a photolithographic alignment mark;

[0008] A first dielectric layer is formed on the substrate, a via is formed in the first dielectric layer, the via exposes the second pattern, and a via metal layer is formed on the first dielectric layer, the via metal layer filling the via and electrically connected to the second pattern.

[0009] The via metal layer located above the first dielectric layer is removed by chemical mechanical polishing, wherein after chemical mechanical polishing of the via metal layer, the upper surface of the first dielectric layer located above the cut channel area is higher than the upper surface of the first dielectric layer located above the pixel area.

[0010] A metal reflective layer is formed on the first dielectric layer, wherein the upper surface of the metal reflective layer above the cut-out area is higher than the upper surface of the metal reflective layer above the pixel area;

[0011] A second dielectric layer is formed on the metal reflective layer, and the second dielectric layer is polished by chemical mechanical polishing. After the second dielectric layer is polished by chemical mechanical polishing, the metal reflective layer located above the cut-out area is exposed, and the metal reflective layer located above the pixel area is covered by the second dielectric layer.

[0012] The metal reflective layer located above the cut area is removed using a cleaning method.

[0013] Optionally, the step of forming the first pattern in the cutting area and the second pattern in the pixel area includes:

[0014] A first groove is formed in the substrate located in the cutting channel area, and a second groove is formed in the substrate located in the pixel area, wherein the pattern density of the second groove is greater than the pattern density of the first groove;

[0015] A bottom metal layer is formed on the substrate, and the bottom metal layer fills the first groove and the second groove;

[0016] The bottom metal layer located above the substrate is removed by chemical mechanical polishing. The bottom metal layer located in the first groove forms the first pattern, and the bottom metal layer located in the second groove forms the second pattern. After chemical mechanical polishing of the bottom metal layer, the upper surface of the substrate located in the cutting area is higher than the upper surface of the substrate located in the pixel area.

[0017] Optionally, after the metal reflective layer is formed on the first dielectric layer, the height difference between the metal reflective layer above the dicing area and the metal reflective layer above the pixel area is:

[0018] Optionally, the metal reflective layer and the first dielectric layer are in direct contact. After the second dielectric layer is chemically mechanically polished, the metal reflective layer located above the cutting area is cleaned and removed in a chemically mechanical polishing apparatus.

[0019] Optionally, a barrier layer is further formed between the metal reflective layer and the first dielectric layer. After removing the metal reflective layer above the cutting channel area by a cleaning method, the barrier layer above the cutting channel area is also removed.

[0020] Optionally, the barrier layer comprises stacked Ti / TiN / TaN layers.

[0021] Optionally, after chemical mechanical polishing of the second dielectric layer, the metal reflective layer and the barrier layer located above the cutting zone are removed by cleaning in a wet cleaning device.

[0022] Optionally, the material of the metal reflective layer includes aluminum.

[0023] Optionally, the first dielectric layer is made of silicon oxide, and the second dielectric layer is made of silicon oxide.

[0024] Optionally, the material of the through-hole metal layer includes tungsten.

[0025] As described above, in the method for fabricating the LCOS device of the present invention, before depositing the metal reflective layer, a height difference is generated between the first dielectric layer above the dicing area and the first dielectric layer above the pixel area, thereby causing a height difference in the deposited metal reflective layer. After chemical mechanical polishing of the second dielectric layer, the metal reflective layer above the dicing area is exposed. The metal reflective layer above the dicing area is removed by a cleaning method so that the first pattern, which serves as a photolithography alignment mark, can be normally recognized by the photolithography machine, and subsequent process steps such as photolithography and etching can be performed. Attached Figure Description

[0026] Figure 1 The diagram shown is a flowchart of the fabrication method of the LCOS device in an embodiment of the present invention.

[0027] Figure 2 The diagram shows the formation of the first and second grooves in an embodiment of the present invention.

[0028] Figure 3 The diagram shown is a schematic diagram of the formation of the bottom metal layer in an embodiment of the present invention.

[0029] Figure 4 The diagram shown illustrates the formation of the first and second patterns in an embodiment of the present invention.

[0030] Figure 5The diagram shown illustrates the formation of the first dielectric layer and the via in an embodiment of the present invention.

[0031] Figure 6 The diagram shown is a schematic diagram of the formation of a through-hole metal layer in an embodiment of the present invention.

[0032] Figure 7 The diagram shown is a schematic of the through-hole metal layer after chemical mechanical polishing in an embodiment of the present invention.

[0033] Figure 8 The diagram shown is a schematic diagram of the formation of a metal reflective layer in an embodiment of the present invention.

[0034] Figure 9 The diagram shown is a schematic diagram of the formation of the second dielectric layer in an embodiment of the present invention.

[0035] Figure 10 The diagram shown is a schematic diagram of the second dielectric layer after chemical mechanical polishing in an embodiment of the present invention.

[0036] Figure 11 The diagram shown is a schematic of removing the metal reflective layer above the cutting channel area in an embodiment of the present invention.

[0037] Component designation explanation

[0038] 1. Base

[0039] 100 Cutting Zone

[0040] 101 pixel area

[0041] 102 First Groove

[0042] 103 Second Groove

[0043] 2. Bottom metal layer

[0044] 3 First Pattern

[0045] 4. Second Pattern

[0046] 5 First dielectric layer

[0047] 6 through holes

[0048] 7 Through-hole metal layer

[0049] 8. Conductive plugs

[0050] 9. Metal reflective layer

[0051] 10 Second dielectric layer

[0052] Steps S1 to S6 Detailed Implementation

[0053] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0054] Please see Figures 1 to 11 It should be noted that the illustrations provided in this embodiment are only schematic representations of the basic concept of the present invention. Therefore, the drawings only show the components related to the present invention and are not drawn according to the actual number, shape and size of the components in the actual implementation. In the actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.

[0055] This embodiment provides a method for fabricating an LCOS device. Please refer to [link / reference]. Figure 1 This includes the following steps:

[0056] S1: Provide a substrate, the substrate including a dicing area and a pixel area, a first pattern is formed in the dicing area, a second pattern is formed in the pixel area, the pattern density of the second pattern is greater than the pattern density of the first pattern, and the first pattern serves as a photolithographic alignment mark;

[0057] S2: A first dielectric layer is formed on the substrate, a through hole is formed in the first dielectric layer, the through hole exposes the second pattern, and a through hole metal layer is formed on the first dielectric layer, the through hole metal layer fills the through hole and is electrically connected to the second pattern;

[0058] S3: The via metal layer located above the first dielectric layer is removed by chemical mechanical polishing, wherein after chemical mechanical polishing of the via metal layer, the upper surface of the first dielectric layer located above the cut channel area is higher than the upper surface of the first dielectric layer located above the pixel area.

[0059] S4: A metal reflective layer is formed on the first dielectric layer, wherein the upper surface of the metal reflective layer above the cut-out area is higher than the upper surface of the metal reflective layer above the pixel area;

[0060] S5: A second dielectric layer is formed on the metal reflective layer, and the second dielectric layer is polished by chemical mechanical polishing, wherein after the second dielectric layer is polished by chemical mechanical polishing, the metal reflective layer located above the cutting channel area is exposed, and the metal reflective layer located above the pixel area is covered by the second dielectric layer.

[0061] S6: Use a cleaning method to remove the metal reflective layer located above the cut area.

[0062] The fabrication method of the LCOS device in this embodiment will be described in detail below with reference to the specific accompanying drawings.

[0063] First, please refer to Figures 2 to 4 Step S1: Provide a substrate 1, the substrate 1 including a dicing area 100 and a pixel area 101, a first pattern 3 is formed in the dicing area 100, a second pattern 4 is formed in the pixel area 101, the pattern density of the second pattern 4 is greater than the pattern density of the first pattern 3, and the first pattern 3 serves as a photolithography alignment mark.

[0064] As an example, the substrate 1 may be a wafer or a functional layer formed on the wafer, without specific limitations.

[0065] As an example, the cutting channel area 100 and the pixel area 101 can be arranged adjacently or not adjacently, without specific restrictions.

[0066] As an example, the steps of forming the first pattern 3 in the cutting area 100 and forming the second pattern 4 in the pixel area 101 include:

[0067] (a) such as Figure 2 As shown, a first groove 102 is formed in the substrate 1 located in the cutting channel area 100, and a second groove 103 is formed in the substrate 1 located in the pixel area 101, wherein the pattern density of the second groove 103 is greater than the pattern density of the first groove 102.

[0068] (ii) Figure 3 As shown, a bottom metal layer 2 is formed on the substrate 1, and the bottom metal layer 2 fills the first groove 102 and the second groove 103;

[0069] (III) Figure 4 As shown, the bottom metal layer 2 located above the substrate 1 is removed by chemical mechanical polishing. The bottom metal layer 2 located in the first groove 102 forms the first pattern 3, and the bottom metal layer 2 located in the second groove 103 forms the second pattern 4. After chemical mechanical polishing of the bottom metal layer 2, the upper surface of the substrate 1 located in the cutting area 100 is higher than the upper surface of the substrate 1 located in the pixel area 101.

[0070] As an example, since the pattern density of the second groove 103 is greater than that of the first groove 102, when the bottom metal layer 2 is filled into the first groove 102 and the second groove 103 and then chemically mechanically polished, the polishing rate of the pixel area 101 is greater than that of the cutting channel area 100, and a height difference will be generated between the substrate located in the cutting channel area 100 and the substrate located in the pixel area 101.

[0071] Next, please refer to Figure 5 and Figure 6 Step S2 is performed: a first dielectric layer 5 is formed on the substrate 1, a through hole 6 is formed in the first dielectric layer 5, the through hole 6 exposes the second pattern 4, and a through hole metal layer 7 is formed on the first dielectric layer 5, and the through hole metal layer 7 fills the through hole 6 and is electrically connected to the second pattern 4.

[0072] As an example, the first dielectric layer 5 is made of silicon oxide. After the first dielectric layer 5 is formed, the through hole 6 is formed by dry etching, wet etching or laser drilling.

[0073] As an example, after the through hole 6 is formed, the through hole metal layer 7 is formed by a deposition process, and the material of the through hole metal layer 7 is tungsten.

[0074] Next, please refer to Figure 7 Step S3: Remove the via metal layer 7 located above the first dielectric layer 5 using chemical mechanical polishing. After chemical mechanical polishing of the via metal layer 7, the upper surface of the first dielectric layer 5 located above the cutting channel area 100 is higher than the upper surface of the first dielectric layer 5 located above the pixel area 101.

[0075] As an example, after the through-hole metal layer 7 is chemically mechanically polished, the through-hole metal layer 7 located in the through-hole 6 constitutes a conductive plug 8.

[0076] As an example, when the via metal layer 7 is chemically mechanically polished, since the via metal layer 7 is filled in the first dielectric layer 5 above the pixel region 101, the polishing rate of the via metal layer above the pixel region 101 is greater than the polishing rate of the via metal layer above the cut channel region 100.

[0077] As an example, a height difference is generated when the bottom metal layer 2 is ground, and a height difference is generated when the through-hole metal layer 7 is ground. The accumulation of the height differences makes the upper surface of the first dielectric layer 5 above the cutting channel area 100 higher than the upper surface of the first dielectric layer 5 above the pixel area 101.

[0078] Next, please refer to Figure 8 Step S4 is executed: a metal reflective layer 9 is formed on the first dielectric layer 5, wherein the upper surface of the metal reflective layer 9 located above the cut channel area 100 is higher than the upper surface of the metal reflective layer 9 located above the pixel area 101.

[0079] As an example, the metal reflective layer 9 is made of aluminum. Since the upper surface of the first dielectric layer 5 above the cut channel area 100 is higher than the upper surface of the first dielectric layer 5 above the pixel area 101, after the metal reflective layer 9 is deposited and formed, the upper surface of the metal reflective layer 9 above the cut channel area 100 is higher than the upper surface of the metal reflective layer 9 above the pixel area 101.

[0080] As an example, the height difference between the metal reflective layer 9 located above the cutting channel area 100 and the metal reflective layer 9 located above the pixel area 101 is... For example, it could be Choose according to your needs.

[0081] Next, please refer to Figure 9 and Figure 10 Step S5: A second dielectric layer 10 is formed on the metal reflective layer 9, and the second dielectric layer 10 is polished by chemical mechanical polishing. After the second dielectric layer 10 is polished by chemical mechanical polishing, the metal reflective layer 9 located above the cutting channel area 100 is exposed, and the metal reflective layer 9 located above the pixel area 101 is covered by the second dielectric layer 10.

[0082] As an example, the material of the second dielectric layer 10 is silicon oxide. Since there is a height difference between the metal reflective layer 9 located above the dicing area 100 and the metal reflective layer 9 located above the pixel area 101, after chemical mechanical polishing of the second dielectric layer 10, the metal reflective layer 9 located above the dicing area 100 can be exposed, and the metal reflective layer 9 located above the pixel area 101 is covered by the second dielectric layer 10.

[0083] Next, please refer to Figure 11 The metal reflective layer 9 located above the cutting channel area 100 is removed by a cleaning method.

[0084] As an example, in this embodiment, the metal reflective layer 9 and the first dielectric layer 5 are in direct contact. After the second dielectric layer 10 is chemically mechanically polished, the metal reflective layer 9 located above the cutting channel area 100 is cleaned and removed in a chemically mechanical polishing device. The metal reflective layer 9 located above the pixel area 101 is covered and protected by the second dielectric layer 10. The cleaning solution includes diluted hydrofluoric acid and ammonia.

[0085] As an example, since the metal reflective layer 9 located above the cutting channel area 100 is removed, the first pattern 2, which serves as a photolithography alignment mark, can be normally recognized by the photolithography machine, and subsequent process steps such as photolithography and etching can be performed.

[0086] As an example, in another example, a barrier layer is further formed between the metal reflective layer 9 and the first dielectric layer 5. The barrier layer comprises stacked Ti / TiN / TaN layers and is used to prevent the metal reflective layer 9 from diffusing into the conductive plug 8. After the second dielectric layer 10 is chemically mechanically polished, the metal reflective layer 9 and the barrier layer located above the cutting channel area 100 are cleaned and removed in a wet cleaning device to ensure effective cleaning and removal.

[0087] In summary, in the fabrication method of the LCOS device of the present invention, before depositing the metal reflective layer, a height difference is created between the first dielectric layer above the dicing area and the first dielectric layer above the pixel area, thereby causing a height difference in the deposited metal reflective layer. After chemical mechanical polishing of the second dielectric layer, the metal reflective layer above the dicing area is exposed. The metal reflective layer above the dicing area is then removed by a cleaning method, so that the first pattern, which serves as a photolithography alignment mark, can be correctly recognized by the photolithography machine, allowing subsequent process steps such as photolithography and etching to proceed. Therefore, the present invention effectively overcomes the various shortcomings of the prior art and has high industrial applicability.

[0088] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A method for fabricating an LCOS device, characterized in that, Includes the following steps: A substrate is provided, the substrate including a dicing area and a pixel area, a first pattern is formed in the dicing area, a second pattern is formed in the pixel area, the pattern density of the second pattern is greater than the pattern density of the first pattern, and the first pattern serves as a photolithographic alignment mark; A first dielectric layer is formed on the substrate, a via is formed in the first dielectric layer, the via exposes the second pattern, and a via metal layer is formed on the first dielectric layer, the via metal layer filling the via and electrically connected to the second pattern. The via metal layer located above the first dielectric layer is removed by chemical mechanical polishing, wherein after chemical mechanical polishing of the via metal layer, the upper surface of the first dielectric layer located above the cut channel area is higher than the upper surface of the first dielectric layer located above the pixel area. A metal reflective layer is formed on the first dielectric layer, wherein the upper surface of the metal reflective layer above the cut-out area is higher than the upper surface of the metal reflective layer above the pixel area; A second dielectric layer is formed on the metal reflective layer, and the second dielectric layer is polished by chemical mechanical polishing. After the second dielectric layer is polished by chemical mechanical polishing, the metal reflective layer located above the cut-out area is exposed, and the metal reflective layer located above the pixel area is covered by the second dielectric layer. The metal reflective layer located above the cut area is removed using a cleaning method.

2. The method for fabricating an LCOS device according to claim 1, characterized in that, The steps of forming the first pattern in the cutting area and forming the second pattern in the pixel area include: A first groove is formed in the substrate located in the cutting channel area, and a second groove is formed in the substrate located in the pixel area, wherein the pattern density of the second groove is greater than the pattern density of the first groove; A bottom metal layer is formed on the substrate, and the bottom metal layer fills the first groove and the second groove; The bottom metal layer located above the substrate is removed by chemical mechanical polishing. The bottom metal layer located in the first groove forms the first pattern, and the bottom metal layer located in the second groove forms the second pattern. After chemical mechanical polishing of the bottom metal layer, the upper surface of the substrate located in the cutting area is higher than the upper surface of the substrate located in the pixel area.

3. The method for fabricating an LCOS device according to claim 1, characterized in that: After the metal reflective layer is formed on the first dielectric layer, the height difference between the metal reflective layer above the cut-out area and the metal reflective layer above the pixel area is:

4. The method for fabricating an LCOS device according to claim 1, characterized in that: The metal reflective layer is in direct contact with the first dielectric layer. After the second dielectric layer is subjected to chemical mechanical polishing, the metal reflective layer located above the cutting area is cleaned and removed in a chemical mechanical polishing device.

5. The method for fabricating an LCOS device according to claim 1, characterized in that: A barrier layer is also formed between the metal reflective layer and the first dielectric layer. After removing the metal reflective layer above the cutting channel area by a cleaning method, the process also includes removing the barrier layer above the cutting channel area.

6. The method for fabricating an LCOS device according to claim 5, characterized in that, The barrier layer comprises stacked Ti / TiN / TaN layers.

7. The method for manufacturing an LCOS device according to any one of claims 5-6, characterized in that: After chemical mechanical polishing of the second dielectric layer, the metal reflective layer and the barrier layer located above the cutting zone are removed by cleaning in a wet cleaning device.

8. The method for fabricating an LCOS device according to claim 1, characterized in that: The material of the metal reflective layer includes aluminum.

9. The method for fabricating an LCOS device according to claim 1, characterized in that: The first dielectric layer is made of silicon oxide, and the second dielectric layer is made of silicon oxide.

10. The method for fabricating an LCOS device according to claim 1, characterized in that: The material of the through-hole metal layer includes tungsten.

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