Silicon-based slit structure and preparation method thereof

Abstract

The present invention provides a silicon-based slit structure and a preparation method thereof, comprising a silicon substrate, a slit, a trapezoidal groove, a light-absorbing material layer and a metal protective layer; the crystal plane orientation of the silicon substrate is (111); the incident surface of the silicon substrate is provided with at least one slit, and the slit structure allows incident light to pass through the silicon substrate; the exit surface of the silicon substrate is provided with a trapezoidal groove, and the length direction of the slit and the length direction of the trapezoidal groove are respectively arranged along the length direction of the silicon substrate; the groove width of the trapezoidal groove gradually increases from the incident surface to the exit surface direction; on the longitudinal section of the silicon substrate, all the slits are connected to the trapezoidal groove, and the two ends of the groove bottom of the trapezoidal groove are spaced from each slit; the light-absorbing material layer is located on the incident surface of the silicon substrate to reduce the reflection of the incident light; the metal protective layer is located on the exit surface of the silicon substrate to prevent stray light from passing through the silicon substrate. The present invention adopts a commonly used semiconductor silicon material processing technology and has the advantages of mass production and low cost.

Description

Technical Field

[0001] The invention relates to the field of optical slits, and in particular to a silicon-based slit structure and a preparation method thereof. Background Art

[0002] The optical properties of an ideal optical slit are as follows Figure 1 As shown, the incident light irradiates the slit from the incident surface, and the light beam passes 100% at the position corresponding to the slit on the exit surface; no light beam passes at the non-slit position on the exit surface, that is, T1=0; at the non-slit position on the incident surface, the reflected light intensity is 0, that is, R1=0%. The traditional slit uses laser to prepare the slit on the metal sheet. When the size of the slit is further reduced, for example, less than 10μm, the edge morphology of the laser-processed metal sheet cannot meet the requirements of the slit. In addition, the light absorption treatment of the metal sheet slit on the incident surface usually adopts the borax process, which cannot achieve 100% light absorption. Summary of the invention

[0003] The present invention is to solve the above problems, and the purpose of the present invention is to provide a silicon-based slit structure with simple structure, low cost and small size.

[0004] To achieve the above object, the present invention adopts the following specific technical solutions:

[0005] A silicon-based slit structure, comprising a silicon substrate, a slit, a trapezoidal groove, a light-absorbing material layer and a metal protective layer;

[0006] The crystal orientation of the silicon substrate is <111> ;

[0007] The incident surface of the silicon substrate is provided with at least one slit, and the slit allows incident light to pass through the silicon substrate;

[0008] The exit surface of the silicon substrate is provided with a trapezoidal groove;

[0009] The width of the trapezoidal groove gradually increases from the incident surface to the exit surface of the silicon substrate; in the longitudinal section of the silicon substrate, all the slits are connected to the trapezoidal groove, and both ends of the bottom of the trapezoidal groove are spaced from each slit;

[0010] The light absorbing material layer is located on the incident surface of the silicon substrate to reduce the reflection of the incident light;

[0011] The metal protection layer is located on the output surface of the silicon substrate to prevent stray light from passing through the silicon substrate.

[0012] Furthermore, the light absorbing material layer is a black silicon structure.

[0013] Furthermore, the material of the metal protective layer is any one of Au, Al, Ni, Ag, and Pt.

[0014] Furthermore, the trapezoidal groove is prepared by a wet etching process.

[0015] A method for preparing a silicon-based slit structure comprises the following steps:

[0016] S1. Provide a silicon substrate;

[0017] S2, preparing a second protective film on the incident surface and preparing a first protective film on the exit surface;

[0018] S3, preparing slits and trapezoidal grooves;

[0019] The step of preparing the slit includes: covering a part of the second protective film with a second photoresist layer to expose an area on the second protective film corresponding to the position of the slit; etching the second protective film and the silicon substrate to form the slit; and removing the second photoresist layer.

[0020] The step of preparing the trapezoidal groove comprises: covering a part of the first protective film with a first photoresist layer to expose a region on the first protective film corresponding to the position of the trapezoidal groove; etching the first protective film and the silicon substrate to form the trapezoidal groove; removing the first photoresist layer;

[0021] S4, removing the first protective film and the second protective film;

[0022] S5, preparing a black silicon structure on a silicon substrate;

[0023] S6, preparing a metal protective layer on the silicon substrate;

[0024] S7, cutting the silicon substrate, the black silicon structure and the metal protective layer to separate a single silicon-based slit structure.

[0025] Furthermore, in step S5, a black silicon structure is prepared by any one of dry etching, wet etching, and femtosecond laser processing.

[0026] Furthermore, in step S6, the metal protective layer is prepared by any one of vacuum electron beam evaporation, sputtering, and thermal evaporation.

[0027] Furthermore, the materials of the second protective film and the first protective film in step S2 are any one of SiO2, Si3N4, Al2O3, and Cr.

[0028] Furthermore, the materials of the second protective film and the first protective film in step S2 are both SiO2, and the method for preparing the first protective film and the second protective film adopts any one of magnetron sputtering, ion beam deposition, chemical vapor deposition, thermal oxidation, and sol-gel method.

[0029] Furthermore, in step S3, the second photoresist layer and the silicon substrate are etched by a dry etching method.

[0030] The present invention can achieve the following technical effects:

[0031] The present invention is particularly suitable for use in apertures. The present invention adopts a commonly used semiconductor silicon material processing technology, has the advantages of mass production and low cost, and is more suitable for application scenarios with small slits. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is a schematic diagram of the optical characteristic structure of an ideal optical slit;

[0033] Figure 2 It is a structural schematic diagram of a single slit silicon-based slit structure disclosed in the present invention;

[0034] Figure 3 It is a structural schematic diagram of a multi-slit silicon-based slit structure disclosed in the present invention;

[0035] Figure 4 is a flow chart of the preparation method disclosed in the present invention;

[0036] Figure 5 It is a schematic diagram of the structure of the silicon substrate disclosed in the present invention;

[0037] Figure 6 It is a schematic structural diagram of a silicon substrate after a protective film is prepared according to the present invention;

[0038] Figure 7 It is a schematic structural diagram of a silicon substrate with a first photoresist layer disclosed in the present invention;

[0039] Figure 8 It is a schematic structural diagram of the silicon substrate after etching the first protective film disclosed in the present invention;

[0040] Fig. 9 It is a schematic structural diagram of a silicon substrate after trapezoidal grooves are prepared according to the present invention;

[0041] Fig.10 It is a schematic structural diagram of the silicon substrate after the first photoresist layer is removed according to the present invention;

[0042] Fig.11 It is a schematic structural diagram of a silicon substrate with a second photoresist layer disclosed in the present invention;

[0043] Fig.12 It is a schematic structural diagram of a silicon substrate for etching a second protective film disclosed in the present invention;

[0044] Fig.13 It is a schematic diagram of the structure of the silicon substrate after preparing the slits disclosed in the present invention;

[0045] Fig.14 It is a schematic structural diagram of the silicon substrate after the protective film is removed disclosed in the present invention;

[0046] Fig.15 It is a schematic structural diagram of a silicon substrate after preparing a black silicon structure disclosed in the present invention;

[0047] Fig.16 It is a schematic diagram of the structure of a silicon substrate after the metal protective layer is prepared according to the present invention.

[0048] Reference numerals:

[0049] Silicon substrate 1, slit 2, trapezoidal groove 3, light absorbing material layer 4, metal protection layer 5, first protection film 11, second protection film 12, first photoresist layer 13, second photoresist layer 14. DETAILED DESCRIPTION

[0050] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and do not constitute a limitation of the present invention.

[0051] like Figure 2-3 The silicon-based slit structure shown includes, from top to bottom, a light absorbing material layer 4, a slit 2, a silicon substrate 1, a trapezoidal groove 3, and a metal protection layer 5. The through hole formed by the slit 2 and the trapezoidal groove 3 runs through the entire silicon-based slit structure.

[0052] The silicon substrate 1 is single crystal, and its crystal plane orientation is <111> The silicon substrate has an incident surface and an exit surface relative to each other, and the thickness between the two surfaces is generally tens to hundreds of microns. The shape of the silicon substrate is not limited, and can be rectangular, square, triangular, circular, etc.

[0053] The slit 2 is provided on the incident surface of the silicon substrate 1, and its width is usually between a few micrometers and tens of millimeters. In particular, the slit of the present invention may include: Figure 2 a slit as shown; or Figure 3 The multiple slits shown may have the same or different widths, and the multiple slits are juxtaposed in the width direction of the silicon substrate 1. The slit 2 allows incident light to pass through the silicon-based slit structure.

[0054] Among them, the trapezoidal groove 3 is located on the exit surface of the silicon substrate 1, and the length direction of the slit 2 and the length direction of the trapezoidal groove 3 are arranged along the length direction of the silicon substrate 1 respectively. From the incident surface of the silicon substrate 1 to its exit surface direction, the groove width of the trapezoidal groove 3 gradually increases. So that in the longitudinal section of the silicon substrate 1, the top edge of the trapezoidal groove 3 is located inside the silicon substrate. The trapezoidal groove 3 is connected with the slit 2, and the two ends of the groove bottom (i.e., the top edge) of the trapezoidal groove 3 are spaced from each slit 2. The design interval means that when there is only one slit 2, the top edge of the trapezoidal groove 3 is wider than the width of the slit; when there are multiple slits 2, there is a gap between the two end points of the top edge and the slit 2, and the silicon substrate 1 is retained. After the incident light passes through the slit 2, the light will diverge, so there is a trapezoidal trapezoidal groove behind the slit 2 to prevent the light from shining on the silicon material. <111> The crystal silicon is wet etched, and the resulting shape is naturally trapezoidal, so the trapezoidal groove 3 is quickly obtained.

[0055] Among them, the light-absorbing material layer 4 is located on the incident surface of the silicon substrate 1 to reduce the reflection of the incident light. The black silicon structure is preferably a black silicon structure, which is an irregular forest of silicon pillars. The preparation of the black silicon structure can be done by dry etching, wet etching, or femtosecond laser processing. The function of the black silicon structure is to absorb incident light and prevent reflection. Black silicon is essentially the same material as silicon-based. Black silicon is just a forest-like structure of silicon (very small in size). Its advantage is that it is the same material and does not require the introduction of other materials and preparation methods. The light-absorbing material layer 4 can also use other light-absorbing materials with high absorption rates generally greater than 90%.

[0056] The metal protective layer 5 is located on the exit surface of the silicon substrate 1 to prevent stray light from passing through the silicon substrate 1. The material of the metal protective layer 5 is any one of Au, Al, Ni, Ag, and Pt, but is not limited thereto. The thickness of the metal reflective layer 5 is set according to actual needs, and its function is to prevent light from passing through.

[0057] A method for preparing a silicon-based slit structure comprises the following steps:

[0058] S1, providing a silicon substrate 1; Figure 4 As shown, the silicon substrate 1 is usually a 4-inch, 6-inch, 8-inch or 12-inch silicon wafer, and a plurality of silicon-based slit structures can be prepared simultaneously on the silicon wafer.

[0059] S2, such as Figure 6As shown, a second protective film 12 is prepared on the incident surface, and a first protective film 11 is prepared on the exit surface; preferably, both protective films are SiO2 films. A first SiO2 film and a second SiO2 film are prepared on the upper and lower surfaces of the silicon substrate 1; the SiO2 film can be grown by magnetron sputtering, ion beam deposition, chemical vapor deposition, thermal oxidation, and sol-gel methods. The SiO2 film plays a role in protecting the pattern in the subsequent Si etching process, and other thin film materials with protective functions can also be used, such as Si3N4 film, Al2O3 film, Cr film, etc.

[0060] S3, preparing the slit 2 and the trapezoidal groove 3; there is no order requirement between preparing the slit 2 or the trapezoidal groove 3.

[0061] The steps of preparing the trapezoidal groove 3 include: forming a first photoresist layer 13 on a partial area of ​​the first protective film 11, such as Figure 7 As shown, the area on the first protective film 11 corresponding to the position of the trapezoidal groove 3 is exposed;

[0062] The portion of the first protective film 11 not covered by the photoresist is etched. Figure 8 As shown; the etching method can be wet etching or dry etching;

[0063] The silicon substrate 1 is etched to prepare a trapezoidal groove 3, such as Fig. 9 As shown; the etching method can be wet etching or dry etching;

[0064] Remove the first photoresist layer 13, such as Fig.10 shown.

[0065] The steps of preparing the slit 2 include:

[0066] A second photoresist 14 is formed on the second protective film 12. Fig.11 As shown; a second photoresist layer 14 is covered on a partial area of ​​the second protective film 12 to expose an area on the second protective film 12 corresponding to the position of the slit 2;

[0067] The portion of the second protective film 12 not covered by the photoresist is etched. Fig.12 As shown; the etching method can be wet etching or dry etching;

[0068] The silicon substrate 1 is etched to prepare a slit 2, such as Fig.13 As shown; in order to better control the width of the slit 2, a dry etching process is usually used;

[0069] S4, removing the second photoresist 14, the first SiO2 film and the second SiO2 film, such as Fig.14 As shown;

[0070] S5, preparing a black silicon structure on the silicon substrate 1; Fig.15 As shown; the black silicon structure 4 and the slit structure 2 are located on the same side of the silicon substrate; the preparation method of the black silicon structure can adopt dry etching, wet etching, or femtosecond laser processing.

[0071] S6, preparing a metal protective layer 5 on the silicon substrate 1; Fig.16 As shown; the metal reflective layer 5 and the trapezoidal groove 3 are located on the same side of the silicon substrate 1; the metal reflective layer material can be Au, Al, Ni, Ag, Pt, etc., but not limited to these. Its preparation method can be vacuum electron beam evaporation, sputtering, thermal evaporation, etc.

[0072] S7, cutting the silicon substrate 1, the black silicon structure and the metal protective layer 5 to separate a single silicon-based slit structure. In particular, when a plurality of silicon-based slit structures are arranged in step S1, the silicon substrate is cut into the following pieces: Figure 2 A single slit device is shown.

[0073] The size of the slit in the present invention is determined by the accuracy of the photolithography process, which overcomes the problem that traditional metal processing uses laser cutting and cannot make small-sized slits; the silicon-based slit has the advantage of high precision in the preparation of small-sized slits; the incident surface of the slit adopts a black silicon structure, which can achieve a high light absorption rate and reduce the adverse effects of reflected light; the exit surface is coated with a metal film to prevent light leakage.

[0074] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0075] Although the embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and cannot be understood as limiting the present invention. Those skilled in the art may change, modify, replace and modify the above embodiments within the scope of the present invention.

[0076] The above specific implementations of the present invention do not constitute a limitation on the protection scope of the present invention. Any other corresponding changes and modifications made based on the technical concept of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. A silicon-based slit structure, characterized in that: It comprises a silicon substrate (1), a slit (2), a trapezoidal groove (3), a light absorbing material layer (4) and a metal protective layer (5); The crystal plane and crystal orientation of the silicon substrate (1) are <111> ; The incident surface of the silicon substrate (1) is provided with at least one slit (2), and the slit (2) allows incident light to pass through the silicon substrate (1); The exit surface of the silicon substrate (1) is provided with a trapezoidal groove (3); The width of the trapezoidal groove (3) gradually increases from the incident surface to the exit surface of the silicon substrate (1); in the longitudinal section of the silicon substrate (1), all the slits (2) are connected to the trapezoidal groove (3), and both ends of the bottom of the trapezoidal groove (3) are spaced from each of the slits (2); The light absorbing material layer (4) is located on the incident surface of the silicon substrate (1) to reduce reflection of the incident light; The metal protection layer (5) is located on the emission surface of the silicon substrate (1) and is used to prevent stray light from passing through the silicon substrate (1).

2. The silicon-based slit structure according to claim 1, characterized in that: The light absorbing material layer (4) is a black silicon structure.

3. The silicon-based slit structure according to claim 1, characterized in that: The material of the metal protective layer (5) is any one of Au, Al, Ni, Ag and Pt.

4. The silicon-based slit structure according to claim 1, characterized in that: The trapezoidal groove (3) is prepared by a wet etching process.

5. A method for preparing the silicon-based slit structure according to claim 2, characterized in that: The following steps are involved: S1, providing the silicon substrate (1); S2, preparing a second protective film (12) on the incident surface, and preparing a first protective film (11) on the exit surface; S3, preparing the slit (2) and the trapezoidal groove (3); The step of preparing the slit (2) comprises: covering a partial area of ​​the second protective film (12) with a second photoresist layer (14) to expose an area on the second protective film (12) corresponding to the position of the slit (2); etching the second protective film (12) and the silicon substrate (1) to form the slit (2); and removing the second photoresist layer (14); The step of preparing the trapezoidal groove (3) comprises: covering a part of the first protective film (11) with a first photoresist layer (13) to expose an area on the first protective film (11) corresponding to the position of the trapezoidal groove (3); etching the first protective film (11) and the silicon substrate (1) to form the trapezoidal groove (3); and removing the first photoresist layer (13); S4, removing the first protective film (11) and the second protective film (12); S5, preparing the black silicon structure on the silicon substrate (1); S6, preparing the metal protective layer (5) on the silicon substrate (1); S7, cutting the silicon substrate (1), the black silicon structure and the metal protective layer (5) to separate a single silicon-based slit structure.

6. The preparation method according to claim 5, characterized in that: In the step S5, the black silicon structure is prepared by any one of dry etching, wet etching and femtosecond laser processing.

7. The preparation method according to claim 5, characterized in that: In the step S6, the metal protective layer (5) is prepared by any one of vacuum electron beam evaporation, sputtering, and thermal evaporation.

8. The preparation method according to claim 5, characterized in that: The materials of the second protective film (12) and the first protective film (11) in the step S2 are any one of SiO2, Si3N4, Al2O3, and Cr.

9. The preparation method according to claim 5, characterized in that: The materials of the second protective film (12) and the first protective film (11) in step S2 are both SiO2, and the method for preparing the second protective film (12) and the first protective film (11) is any one of magnetron sputtering, ion beam deposition, chemical vapor deposition, thermal oxidation, and sol-gel method.

10. The preparation method according to claim 5, characterized in that: In step S3, the second photoresist layer (14) and the silicon substrate (1) are etched using a dry etching method.

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