Table surface etching method of infrared detector

Abstract

The invention relates to a mesa etching method of an infrared detector. The mesa etching method comprises the following steps: depositing a first etching mask layer on a material to be etched; depositing a second etching mask layer on the first etching mask layer, wherein the second etching mask layer only covers partial region of the first etching mask layer; synchronously etching the first etching mask layer and the second etching mask layer to form a first mask table board and a second mask table board; etching the material to be etched to form a deep mesa and a shallow mesa; and removing the etching mask layer, and respectively taking the deep mesa area and the shallow mesa area as a common electrode area and a pixel area of the infrared detector. According to the method, two layers of masks are formed through two times of deposition, the thickness difference of the masks of different functional areas is achieved, then the structural combination of the deep mesa and the shallow mesa can be completed at the same time through one-step mask etching and one-step mesa etching, therefore, the processing steps are greatly reduced, the production efficiency is improved, and the detection sensitivity of the infrared detector is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of semiconductor manufacturing, and in particular to a mesa etching method for an infrared detector. Background Art

[0002] In the structural design of electronic components such as infrared focal plane chips, it is usually necessary to form deep mesa and shallow mesa structures through etching to set up different functional areas.

[0003] In order to obtain a structure with both the deep and shallow mesas mentioned above, the existing technology usually requires two etchings to obtain the shallow and deep mesas respectively. The entire process flow is complicated and has many processing steps, which seriously affects production efficiency. Secondly, after the mesa is etched, the side wall of the material is in contact with the outside world for a long time and cannot be passivated in time, which further causes damage to the side wall of the material, seriously affecting the sensitivity of electronic components. Summary of the Invention

[0004] The purpose of the present invention is to provide a mesa etching method for an infrared detector, which forms two layers of masks through two depositions to achieve different mask thicknesses in different functional areas. Then, the structural combination of deep mesas and shallow mesas can be completed simultaneously through one-step mask etching and one-step mesa etching, thereby greatly reducing the number of processing steps, improving production efficiency, and helping to improve the detection sensitivity of infrared detectors.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] A method for etching a mesa of an infrared detector is provided, comprising the following steps:

[0007] depositing a first etching mask layer on the material to be etched;

[0008] Depositing a second etch mask layer on the first etch mask layer, wherein the second etch mask layer only covers a partial area of ​​the first etch mask layer;

[0009] performing synchronous etching on the first etch mask layer and the second etch mask layer to form a first mask mesa on the first etch mask layer not covered by the second etch mask layer, and forming a second mask mesa on the second etch mask layer;

[0010] Using the first mask mesa and the second mask mesa as mask plates, etching the material to be etched to form a deep mesa located below the first mask mesa and a shallow mesa located below the second mask mesa on the material to be etched;

[0011] The first etching mask layer and the second etching mask layer are removed, and the deep mesa region and the shallow mesa region are used as the common electrode region and the pixel region of the infrared detector respectively.

[0012] Preferably, the material to be etched is a material used to manufacture infrared detectors and can be etched.

[0013] Preferably, a first photoresist layer is coated on the first etch mask layer, and the first photoresist layer is photoetched to obtain a hollow area that exposes a portion of the first etch mask layer area;

[0014] A second etch mask layer is deposited on the upper surface of the first etch mask layer in the hollow area.

[0015] Preferably, a second photoresist layer is coated on the second etch mask layer and on the first etch mask layer not covered by the second etch mask layer, and the second photoresist layer is photolithographically processed to form a first photoresist mesa on the first etch mask layer not covered by the second etch mask layer, and a second photoresist mesa on the second etch mask layer;

[0016] The first etch mask layer between two adjacent first photoresist mesas on the side of the second etch mask layer is etched to form a first mask mesa, and the second etch mask layer between two adjacent second photoresist mesas on the upper surface of the second etch mask layer is etched to form a second mask mesa.

[0017] Preferably, all first photoresist mesas have the same height, and all second photoresist mesas have the same height.

[0018] Preferably, the height of the first photoresist mesa is greater than the height of the second photoresist mesa.

[0019] Preferably, a first mask mesa is correspondingly formed under each first photoresist mesa, and a second mask mesa is correspondingly formed under each second photoresist mesa.

[0020] Preferably, when etching the first etch mask layer between two adjacent first photoresist mesas, the etching depth is equal to the thickness of the first etch mask layer.

[0021] Preferably, when etching the second etch mask layer between two adjacent second photoresist mesas, the etching depth is less than or equal to the thickness of the second etch mask layer.

[0022] Preferably, the heights of all the deep mesas are the same, and the heights of all the shallow mesas are the same, and the height of the deep mesas is greater than that of the shallow mesas.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] The present invention forms two layers of masks through two depositions to achieve different mask thicknesses in different functional areas. As a result, the area covered only by the first etching mask layer can be used as the shallow mesa formation area, and the area covered by the first etching mask layer and the second etching mask layer can be used as the deep mesa formation area. Then, the structural combination of the deep mesa and the shallow mesa can be completed simultaneously through one-step mask etching and one-step mesa etching, thereby greatly reducing the processing steps, improving production efficiency, and indirectly reducing the exposure time of the mesa sidewall, which helps to improve the detection sensitivity of the infrared detector. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 The figure is a flow chart of the steps of the mesa etching method of the mid-infrared detector of the present invention. DETAILED DESCRIPTION

[0026] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0027] Example 1

[0028] like Figure 1 As shown, this embodiment provides a method for etching a mesa of an infrared detector, which includes the following steps:

[0029] S1, cleaning the material to be etched 100, and then depositing a first etching mask layer 1 on the material to be etched 100;

[0030] In this embodiment, the first etching mask layer 1 can be obtained by chemical vapor deposition or physical vapor deposition, and the first etching mask layer 1 can be silicon dioxide (SiO2); at the same time, the material to be etched 100 can be any material used to manufacture infrared detectors and can be etched. For example, in this embodiment, the material to be etched 100 includes a superlattice material or a mercury cadmium telluride material, and can be divided into different functional layers, such as a barrier layer 101, a lower contact layer 102, etc.

[0031] S2, coating a first photoresist layer 2 with a uniform thickness on the upper surface of the first etching mask layer 1, and exposing the first photoresist layer 2 through a mask to complete a first photolithography and obtain a first photolithography layer;

[0032] The first photoresist layer 2 is a positive photoresist or a negative photoresist, and has a thickness of 0.1 μm to 20 μm. The specific thickness can be determined according to factors such as the properties of the material 100 to be etched and the photolithographic pattern. The first photoresist layer includes a hollow area A for exposing a portion of the upper surface of the first etch mask layer 1, and a portion of the first photoresist layer 2 remaining on the side of the hollow area A after the first photolithography is completed.

[0033] S3, depositing a second etching mask layer 3 on the upper surface of the first etching mask layer 1 in the hollow area A; wherein the deposition method, material and thickness of the first etching mask layer 1 and the second etching mask layer 3 are the same;

[0034] And, after the second etching mask layer 3 is formed, all remaining first photoresist layers 2 are removed to expose the upper surface of the material to be etched 100 covered by the remaining first photoresist layer 2;

[0035] S4, coating a second photoresist layer 4 on the upper surface of the second etch mask layer 3 and the upper surface of the first etch mask layer 1 on both sides of the second etch mask layer 3 that is not covered by the second etch mask layer 3, and exposing the second photoresist layer 4 through a mask to complete a second photolithography and obtain a second photoresist layer;

[0036] The second photoresist layer includes a first photoresist mesa 21 formed on the second photoresist layer 4 on the side of the second etch mask layer 3 and a second photoresist mesa 41 formed on the second photoresist layer 4 on the upper surface of the second etch mask layer 3. Preferably, in this embodiment, a plurality of first photoresist mesas 21 are correspondingly formed on the second photoresist layer 4 on both sides of the second etch mask layer 3, and there are a plurality of second photoresist mesas 41. At the same time, the heights of all the first photoresist mesas 21 are the same, the heights of all the second photoresist mesas 41 are the same, and the height of the first photoresist mesas 21 is greater than the height of the second photoresist mesas 41.

[0037] Wherein, the second photoresist layer 4 is a positive photoresist or a negative photoresist, and has a thickness of 0.1 μm to 20 μm;

[0038] S5, etching the first etch mask layer 1 between two adjacent first photoresist mesas 21 on the side of the second etch mask layer 3 to form a first mask mesa 11, and etching the second etch mask layer 3 between two adjacent second photoresist mesas 41 on the upper surface of the second etch mask layer 3 to form a second mask mesa 31; and etching the first etch mask layer 1 and the second etch mask layer 3 simultaneously;

[0039] Wherein, a plurality of first mask mesas 11 and a plurality of second mask mesas 31 are correspondingly formed on both sides of the second etching mask layer 3; and a first mask mesa 11 is correspondingly formed under each first photoresist mesa 21, and a second mask mesa 31 is correspondingly formed under each second photoresist mesa 41;

[0040] At the same time, when etching the area between two adjacent first photoresist mesas 2 on the side of the second etch mask layer 3, the etching depth is equal to the thickness of the first etch mask layer 1, thereby exposing the surface of the material 100 to be etched between the two adjacent first mask mesas 11; and when etching the area between two adjacent second photoresist mesas 41 on the upper surface of the second etch mask layer 3, the etching depth is less than or equal to the thickness of the second etch mask layer 3;

[0041] S6. Remove all remaining second photoresist layer 4, and use the first mask mesas 11 and the second mask mesas 31 as mask plates to etch the material 100 to be etched between two adjacent first mask mesas 11 to form at least one deep mesa 12 on the material 100 to be etched, and etch the material 100 to be etched between two adjacent second mask mesas 31 to form at least one shallow mesa 32 on the material 100 to be etched;

[0042] In this embodiment, each deep mesa 12 corresponds to a first mask mesa 11, and each shallow mesa 32 corresponds to a second mask mesa 31; and there are multiple deep mesas 12 and shallow mesas 32;

[0043] The heights of all the deep mesas 12 are the same, and the heights of all the shallow mesas 32 are the same, and the height of the deep mesas 12 is greater than the height of the shallow mesas 32;

[0044] S7 , removing all remaining first etching mask layer 1 and all remaining second etching mask layer 3 , and using the deep mesa 12 as the common electrode region of the infrared detector, and using the shallow mesa 32 as the pixel region of the infrared detector.

[0045] To sum up, this embodiment forms two layers of masks through two depositions to achieve different mask thicknesses in different functional areas. For example, when manufacturing an infrared detector chip, the area covered only by the first etching mask layer can be used as the shallow mesa formation area, and the area covered by the first etching mask layer and the second etching mask layer can be used as the deep mesa formation area. Then, the structural combination of the deep mesa and the shallow mesa can be completed simultaneously through one-step mask etching (i.e., step S5) and one-step mesa etching (i.e., step S6). Compared with traditional processing technology, it greatly reduces the processing steps, improves production efficiency, and indirectly reduces the exposure time of the mesa side wall, which helps to improve the detection sensitivity of the infrared detector.

[0046] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for etching a mesa of an infrared detector, characterized in that: The steps include: depositing a first etching mask layer on the material to be etched; Depositing a second etch mask layer on the first etch mask layer, wherein the second etch mask layer only covers a partial area of ​​the first etch mask layer; performing synchronous etching on the first etch mask layer and the second etch mask layer to form a first mask mesa on the first etch mask layer not covered by the second etch mask layer, and forming a second mask mesa on the second etch mask layer; Using the first mask mesa and the second mask mesa as mask plates, etching the material to be etched to form a deep mesa located below the first mask mesa and a shallow mesa located below the second mask mesa on the material to be etched; The first etching mask layer and the second etching mask layer are removed, and the deep mesa region and the shallow mesa region are used as the common electrode region and the pixel region of the infrared detector respectively.

2. The mesa etching method according to claim 1, wherein: The material to be etched is a material used to manufacture infrared detectors and can be etched.

3. The mesa etching method according to claim 1, wherein: Coating a first photoresist layer on the first etch mask layer, and performing photolithography on the first photoresist layer to obtain a hollow area that exposes a portion of the first etch mask layer area; A second etch mask layer is deposited on the upper surface of the first etch mask layer in the hollow area.

4. The mesa etching method according to claim 1, wherein: Coating a second photoresist layer on the second etch mask layer and on the first etch mask layer not covered by the second etch mask layer, and performing photolithography on the second photoresist layer to form a first photoresist mesa on the first etch mask layer not covered by the second etch mask layer, and forming a second photoresist mesa on the second etch mask layer; The first etch mask layer between two adjacent first photoresist mesas on the side of the second etch mask layer is etched to form a first mask mesa, and the second etch mask layer between two adjacent second photoresist mesas on the upper surface of the second etch mask layer is etched to form a second mask mesa.

5. The mesa etching method according to claim 4, wherein: The heights of all the first photoresist mesas are the same, and the heights of all the second photoresist mesas are the same.

6. The mesa etching method according to claim 4, wherein: The height of the first photoresist mesa is greater than the height of the second photoresist mesa.

7. The mesa etching method according to claim 4, wherein: A first mask mesa is correspondingly formed under each first photoresist mesa, and a second mask mesa is correspondingly formed under each second photoresist mesa.

8. The mesa etching method according to claim 1, wherein: When etching the first etching mask layer between two adjacent first photoresist mesas, the etching depth is equal to the thickness of the first etching mask layer.

9. The mesa etching method according to claim 1, wherein: When etching the second etch mask layer between two adjacent second photoresist mesas, the etching depth is less than or equal to the thickness of the second etch mask layer.

10. The mesa etching method according to claim 1, wherein: All deep countertops have the same height, and all shallow countertops have the same height, and the height of the deep countertops is greater than the height of the shallow countertops.

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