US-12619017-B2 - Optical filter and method of producing the same

US12619017B2US 12619017 B2US12619017 B2US 12619017B2US-12619017-B2

Abstract

The present disclosure relates to an optical filter and a method of producing the same. In the producing method, a thermal evaporation deposition process of a sacrificial layer, and depositions process of a base layer and a dielectric stack layer are sequentially performed on a substrate having a trench with a specific width, so that the base layer and the dielectric stack layer extend outward to form a solidified structure with a specific length. Next, a fixed layer is affixed to the dielectric stack layer, and the sacrificial layer is removed using a solvent to remove the substrate. As such, structural strength and flatness of the produced optical filter are enhanced, and a volume thereof is reduced, such that the optical filter can be applied to automated processes of miniaturized elements.

Inventors

Chi-Ming Yu
Zong Han LI
Chin-Pin YEH

Assignees

APOGEE OPTOCOM CO., LTD.

Dates

Publication Date: 20260505
Application Date: 20230926
Priority Date: 20220927

Claims (12)

1 . A method of producing an optical filter, comprising: providing a substrate having at least one trench, wherein a width of the at least one trench is not less than 0.1 mm, and the at least one trench divides the substrate into at least two regions; and performing a thermal evaporation deposition process on the substrate to form a sacrificial layer on the at least two regions; after performing the thermal evaporation deposition process, performing a deposition process on the sacrificial layer to sequentially deposit a first base layer and a dielectric stack layer on the sacrificial layer in the at least two regions, wherein the deposition process comprises an ion beam-assisted evaporation, and the first base layer and the dielectric stack layer extend outward to form a solidified structure, and a length of the solidified structure is less than 15 μm, and the length of the solidified structure is defined as the longest length of the solidified structure measured in a direction parallel to the width of the at least one trench based on an inner wall of the at least one trench as a starting point of the solidified structure; affixing a fixed layer on the dielectric stack layer in the at least two regions, so that the dielectric stack layer is fixed on the fixed layer to form at least one prototype optical filter on the sacrificial layer in the at least two regions; removing the sacrificial layer with a solvent to separate the at least one prototype optical filter from the substrate, wherein a material of the sacrificial layer is water-soluble; and irradiating the fixed layer with light to separate the optical filter from the fixed layer.
2 . The method of producing the optical filter of claim 1 , wherein a depth of the at least one trench is not less than 0.1 mm.
3 . The method of producing the optical filter of claim 1 , wherein when performing the thermal evaporation deposition process, a temperature of the substrate is set at 140° C. to 160° C.
4 . The method of producing the optical filter of claim 1 , wherein the thermal evaporation deposition process is performed without using an ion beam.
5 . The method of producing the optical filter of claim 1 , wherein an included angle between a deposition direction of the thermal evaporation deposition process and a normal direction of a surface of the sacrificial layer is 10 degrees to 40 degrees.
6 . The method of producing the optical filter of claim 1 , wherein a voltage and a current of the ion beam-assisted evaporation are 500V to 700V and 500 mA to 700 mA, respectively.
7 . The method of producing the optical filter of claim 1 , wherein an included angle between a deposition direction of the deposition process and a normal direction of a surface of the first base layer is 10 degrees to 40 degrees.
8 . The method of producing the optical filter of claim 1 , wherein an included angle between a deposition direction of the deposition process and a normal direction of a surface of the dielectric stack layer is 10 degrees to 40 degrees.
9 . The method of producing the optical filter of claim 1 , wherein the dielectric stack layer comprises: at least one first dielectric layer, and at least one second dielectric layer alternately stacked with the at least one first dielectric layer, wherein a first refractive index of the at least one first dielectric layer is not equal to a second refractive index of the at least one second dielectric layer.
10 . The method of producing the optical filter of claim 1 , wherein a thickness of the first base layer is not less than 3 μm.
11 . The method of producing the optical filter of claim 1 , wherein the material of the sacrificial layer comprises a salt of hexafluoroaluminic acid, and the solvent comprises water.
12 . The method of producing the optical filter of claim 1 , wherein before affixing the fixed layer on the dielectric stack layer, the method further comprises depositing a second base layer on the dielectric stack layer.

Description

RELATED APPLICATION This application claims priority to Taiwan Application Serial Number 111136443, filed Sep. 27, 2022, which is herein incorporated by reference. BACKGROUND Field of Invention The present disclosure relates to an optical filter and a method of producing the same, and in particular to a substrate-free optical filter having a solidified structure and a method of producing the same. Description of Related Art Traditionally, a method of producing an optical filter made of a dielectric material is to use a substrate as a base layer, and to deposit a dielectric stack layer on the substrate. This producing method utilizes the substrate to provide reinforcement to the weak dielectric stack layer to prevent damage during subsequent assembly processes such as clamping. However, since a material of the dielectric stack layer and a material of the substrate are different, and producing processes of the two are also different, stress is generated between the dielectric stack layer and the substrate. The stress causes the optical filter to warp during the subsequent assembly processes (especially when the optical filter is bonded to an optical element such as a lens or a prism), which affects a yield of a finished product. Generally, flatness of the dielectric stack layer is maintained by increasing a thickness of the substrate to more than several times a thickness of the dielectric stack layer. However, the thickened substrate also increases a volume of the optical filter, so that the optical filter cannot be bonded to a miniaturized optical element by transfer printing, so it is not suitable for automatic mass production of miniaturized elements. In addition, with miniaturization of the optical element, there is a demand for reducing an area of the optical filter. Although a traditional cutting method can reduce the area of the optical filter, a cut portion of the optical filter is easy to be damaged. In view of this, there is an urgent need to develop a novel optical filter and a method of producing the same to improve the above shortcomings. SUMMARY In view of the above issues, one aspect of the present disclosure provides a method of producing an optical filter. The producing method utilizes a substrate having a trench with a specific width to form a solidified structure with a specific length, and removes the substrate by removing a sacrificial layer, so as to improve structural strength and flatness of the produced optical filter and reduce a volume thereof. Another aspect of the present disclosure provides an optical filter. The optical filter is produced by the above-mentioned method. According to one aspect of the present disclosure, a method of producing an optical filter is provided. In the producing method, a substrate having at least one trench is provided, in which a width of the at least one trench is not less than 0.1 mm, and the at least one trench divides the substrate into at least two regions. A thermal evaporation deposition process is performed on the substrate to deposit a sacrificial layer on the at least two regions. After performing the thermal evaporation deposition process, a deposition process is performed on the substrate to sequentially deposit a first base layer and a dielectric stack layer on the sacrificial layer in the at least two regions, in which the first base layer and the dielectric stack layer extend outward to form a solidified structure, and a length of the solidified structure is less than 15 μm. A fixed layer is affixed on the dielectric stack layer in the at least two regions, so that the dielectric stack layer is fixed on the fixed layer to form at least one prototype optical filter on the sacrificial layer in the at least two regions. The sacrificial layer is removed with a solvent to separate the at least one prototype optical filter from the substrate. The fixed layer is irradiated with light to separate the optical filter from the fixed layer. According to one embodiment of the present disclosure, a depth of the at least one trench is not less than 0.1 mm. According to another embodiment of the present disclosure, when performing the thermal evaporation deposition process, a temperature of the substrate is set at 140° C. to 160° C. According to one embodiment of the present disclosure, the thermal evaporation deposition process is performed without using an ion beam. According to one embodiment of the present disclosure, an included angle between a deposition direction of the thermal evaporation deposition process and a normal direction of a surface of the sacrificial layer is 10 degrees to 40 degrees. According to a further embodiment of the present disclosure, the deposition process comprises an ion beam-assisted evaporation, and a voltage and a current of the ion beam-assisted evaporation are 500V to 700V and 500 mA to 700 mA, respectively. According to one embodiment of the present disclosure, an included angle between a deposition direction of t