Formation method of MEMS three-axis AMR magnetic sensor

Abstract

The invention provides a method for forming an MEMS (Micro Electro Mechanical System) triaxial AMR (Adaptive Magnetic Resonance) magnetic sensor, which comprises the following steps of: providing a substrate structure with a groove, and sequentially forming a magnetic material layer and a protective layer on the surface of the substrate structure; forming a photoresist pattern by adopting a photoetching process, and etching the protective layer by taking the photoresist pattern as a mask; etching the groove by using an ion beam etching process with an incident angle of 70 degrees so as to remove the polymer; carrying out ashing treatment to remove the photoresist pattern; cleaning the groove by a wet method; and etching the magnetic material layer by using an ion beam etching process with an incident angle of 130 degrees to form the MEMS three-axis AMR magnetic sensor. When the protective layer and the magnetic material layer in the groove are etched, polymer residues at the bottom of the deep groove are effectively cleaned through two times of split ion beam etching with different incident angles, and the yield of the formed MEMS three-axis AMR magnetic sensor is greatly improved.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor manufacturing technology, and in particular to a method for forming a MEMS three-axis AMR magnetic sensor. Background Art

[0002] The magnetic material layer of the existing MEMS three-axis AMR magnetic sensor is generally formed of Permalloy, that is, nickel-iron (NiFe) alloy, and its protective layer is generally formed of tantalum nitride TaN. For MEMS three-axis AMR magnetic sensor products, such as Figure 1 and Figure 2 As shown in FIG. 1 , the TaN polymer residue produced during the etching of deep trenches (>3UM) of tantalum nitride (TaN) is difficult to remove, which may result in a low yield in severe cases. Figure 3 As shown in Figure 1, we traced the source of polymer and found that after etching TAN, thick polymer had already accumulated on the sidewalls of the photoresist (PR). Therefore, cleaning the polymer becomes the primary task after etching, and it is also the difficulty of etching this layer. We need a new method to solve this problem. Summary of the invention

[0003] In order to solve the above problems in the prior art, the present invention provides a method for forming a MEMS three-axis AMR magnetic sensor, which is used to effectively remove polymer residues at the bottom of the groove and improve the yield of the MEMS three-axis AMR magnetic sensor.

[0004] The present invention provides a method for forming a MEMS three-axis AMR magnetic sensor, comprising the following steps:

[0005] Step 1, providing a substrate structure with grooves, and sequentially forming a magnetic material layer and a protective layer on the surface of the substrate structure;

[0006] Step 2: forming a photoresist pattern by using a photolithography process, and etching the protective layer using the photoresist pattern as a mask;

[0007] Step 3, etching the groove using an ion beam etching process with an incident angle of 70 degrees to remove the polymer;

[0008] Step 4: performing an ashing process to remove the photoresist pattern;

[0009] Step 5: wet cleaning the groove;

[0010] Step six: etching the magnetic material layer using an ion beam etching process with an incident angle of 130 degrees to form the MEMS three-axis AMR magnetic sensor.

[0011] Preferably, the magnetic material layer in step one is an iron-nickel alloy layer.

[0012] Preferably, the protective layer in step one is a tantalum nitride layer.

[0013] Preferably, the protection layer in step 1 is used to prevent the magnetic material layer from being oxidized, and the side surface of the groove is used to form a Z-axis AMR magnetic sensor.

[0014] Preferably, the step 2 of forming a photoresist pattern by using a photolithography process includes the steps of depositing a hard mask layer, coating a photoresist, and exposing and developing.

[0015] Preferably, the photoresist pattern in step 2 covers the formation area of ​​the MEMS three-axis AMR magnetic sensor and opens the outside of the formation area of ​​the three-axis AMR magnetic sensor, and the formation area of ​​the Z-axis AMR magnetic sensor is located on the side of the groove and covers and extends to the substrate surface outside the groove.

[0016] Preferably, the polymer in step three is generated by etching the protective layer, including a polymer formed on the sidewall of the photoresist.

[0017] The method for forming the MEMS three-axis AMR magnetic sensor of the present invention is to etch the groove tantalum nitride TAN, and then use an ion beam etching process with an incident angle of 70 degrees to etch the groove to remove the generated polymer, so that the polymer at the bottom of the groove can be removed, and the polymer residue at the bottom of the deep groove is effectively cleaned, thereby obtaining a MEMS three-axis AMR magnetic sensor product with greatly improved yield. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The above and other objects, features and advantages of the present invention will become more apparent through the following description of the embodiments of the present invention with reference to the accompanying drawings, in which:

[0019] Figure 1 Schematic diagram showing the polymer residue at the bottom of the trench;

[0020] Figure 2 Schematic diagram showing thick polymer accumulation on the sidewalls of the photoresist after etching TAN;

[0021] Figure 3 A flowchart showing a method for forming a MEMS three-axis AMR magnetic sensor according to an embodiment of the present invention;

[0022] Figures 4 to 7 Shown is a schematic structural diagram of each step of a method for forming a MEMS three-axis AMR magnetic sensor according to an embodiment of the present invention;

[0023] Figure 8 Display as Figure 7 Corresponding electron microscope photographs. DETAILED DESCRIPTION

[0024] The present invention is described below based on embodiments, but the present invention is not limited to these embodiments. In the detailed description of the present invention below, some specific details are described in detail. It is possible for a person skilled in the art to fully understand the present invention without the description of these details. In order to avoid confusing the essence of the present invention, known methods, processes, flows, components and circuits are not described in detail.

[0025] In addition, persons of ordinary skill in the art will appreciate that the drawings provided herein are for illustration purposes and are not necessarily drawn to scale.

[0026] Unless the context clearly requires otherwise, the words "include", "comprising" and similar words throughout the application should be interpreted as including rather than exclusive or exhaustive; that is, the meaning is "including but not limited to".

[0027] In the description of the present invention, it should be understood that the terms "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance. In addition, in the description of the present invention, unless otherwise specified, "plurality" means two or more.

[0028] The manufacturing method of the existing MEMS three-axis AMR magnetic sensor includes: etching the protective layer; performing ashing treatment; wet cleaning the groove and performing ion beam etching. However, the polymer generated after etching the protective layer remains at the bottom of the groove, resulting in reduced device performance and low product yield. Therefore, the present invention proposes a new method for forming a MEMS three-axis AMR magnetic sensor to effectively clean the polymer residue at the bottom of the groove. The technical solution of the present invention is further explained below in conjunction with the accompanying drawings and through specific implementation methods.

[0029] Figure 3 A flowchart showing a method for forming a MEMS three-axis AMR magnetic sensor according to an embodiment of the present invention; Figures 4 to 7 The structure diagram of each step of the method for forming a MEMS three-axis AMR magnetic sensor according to an embodiment of the present invention is shown. Figure 3 As shown, the method for forming the MEMS three-axis AMR magnetic sensor according to the embodiment of the present invention comprises the following steps:

[0030] Step 1: providing a substrate structure with grooves, and sequentially forming a magnetic material layer and a protective layer on the surface of the substrate structure.

[0031] In the embodiment of the present invention, the material of the substrate may be silicon, germanium, silicon germanium or silicon carbide, or may be silicon on insulator (SOI) or germanium on insulator (GOI), or may be other materials, such as III and V group compounds such as gallium arsenide. The substrate in this embodiment is a silicon substrate, and further, it may be an undoped or lightly doped silicon substrate. An insulating layer is formed on the surface of the silicon substrate, and a groove is formed in the insulating layer. The insulating layer is a silicon oxide layer.

[0032] The top width of the groove is greater than the bottom width. The protective layer is used to prevent the magnetic material layer from being oxidized, and the side of the groove is used to form a Z-axis AMR magnetic sensor. The magnetic material layer is an iron-nickel alloy layer, and the protective layer is a tantalum nitride layer.

[0033] Step 2: using a photolithography process to form a photoresist pattern, and using the photoresist pattern as a mask to etch the protective layer.

[0034] The photolithography process is used to form a photoresist pattern, including depositing a hard mask layer, applying photoresist, and exposing and developing steps. There are many materials for the hard mask layer. In the embodiment of the present invention, the material of the hard mask layer is titanium nitride or silicon nitride. Usually it is silicon nitride (SiN), and its formation method can be chemical vapor deposition (CVD) or physical vapor deposition (PVD). The photoresist pattern covers the formation area of ​​the MEMS three-axis AMR magnetic sensor and opens the outside of the formation area of ​​the three-axis AMR magnetic sensor. The formation area of ​​the Z-axis AMR magnetic sensor is located on the side of the groove and covers and extends to the substrate surface outside the groove, such as Figure 4 As shown, the formed photoresist pattern is shown.

[0035] The protective layer is etched using the photoresist pattern as a mask, that is, the tantalum nitride TAN layer is etched. In the existing method, the etching is a reactive ion etching using carbon and fluorine-based etching gases. Reactive ion etching with carbon and fluorine-based etching gases easily forms a polymer on the surface of the photoresist (PR) pattern. Figure 5 As shown, after etching, polymer is generated in the trench and formed on the sidewalls of the photoresist.

[0036] Step 3: Etch the grooves using an ion beam etching process with an incident angle of 70 degrees to remove the polymer.

[0037] In the embodiment of the present invention, Figure 6 As shown, the polymer is removed by etching using an ion beam etching process with an incident angle of 70 degrees.

[0038] Step 4: Perform ashing treatment to remove the photoresist pattern.

[0039] Here, the specific ashing process is not described in detail.

[0040] Step 5: wet cleaning the groove.

[0041] In the embodiment of the present invention, the trench is cleaned by wet etching to remove impurities in the trench.

[0042] Step 6: Use an ion beam etching process with an incident angle of 130 degrees to etch the magnetic material layer to form a MEMS three-axis AMR magnetic sensor.

[0043] In the embodiment of the present invention, Figure 7 As shown, the magnetic material layer is removed by etching using an ion beam etching process with an incident angle of 120 degrees, thereby forming a MEMS three-axis AMR magnetic sensor.

[0044] The embodiment of the present invention etches different film layers through two separate ion beam etchings at two different incident angles, wherein the first etching is specifically for TAN polymer, effectively cleaning the polymer residue at the bottom of the deep groove. Figure 8 As shown, it is shown as Figure 7 Corresponding electron microscope photos. Figure 2 Obviously, the deep grooves in the embodiment of the present invention are relatively gentle and the surface is relatively flat.

[0045] The method for forming the MEMS three-axis AMR magnetic sensor of the present invention is to etch the groove tantalum nitride TAN, and then use an ion beam etching process with an incident angle of 70 degrees to etch the groove to remove the generated polymer, so that the polymer at the bottom of the groove can be removed, and the polymer residue at the bottom of the deep groove is effectively cleaned, thereby obtaining a MEMS three-axis AMR magnetic sensor product with greatly improved yield.

[0046] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for forming a MEMS three-axis AMR magnetic sensor, It is characterized in that The following steps are involved: Step 1, providing a substrate structure with grooves, and sequentially forming a magnetic material layer and a protective layer on the surface of the substrate structure; Step 2: forming a photoresist pattern by using a photolithography process, and etching the protective layer using the photoresist pattern as a mask; Step 3, etching the groove using an ion beam etching process with an incident angle of 70 degrees to remove the polymer; Step 4: performing an ashing process to remove the photoresist pattern; Step 5: wet cleaning the groove; Step six: etching the magnetic material layer using an ion beam etching process with an incident angle of 130 degrees to form the MEMS three-axis AMR magnetic sensor.

2. The method for forming the MEMS three-axis AMR magnetic sensor according to claim 1, It is characterized in that The magnetic material layer in step one is an iron-nickel alloy layer.

3. The method for forming the MEMS three-axis AMR magnetic sensor according to claim 1, It is characterized in that The protective layer in step 1 is a tantalum nitride layer.

4. The method for forming the MEMS three-axis AMR magnetic sensor according to claim 1, It is characterized in that The protection layer in step 1 is used to prevent the magnetic material layer from being oxidized, and the side surface of the groove is used to form a Z-axis AMR magnetic sensor.

5. The method for forming the MEMS three-axis AMR magnetic sensor according to claim 1, It is characterized in that The step 2 of forming a photoresist pattern by using a photolithography process includes depositing a hard mask layer, coating a photoresist, and exposing and developing steps.

6. The method for forming the MEMS three-axis AMR magnetic sensor according to claim 1, It is characterized in that In step 2, the photoresist pattern covers the formation area of ​​the MEMS three-axis AMR magnetic sensor and opens the outside of the formation area of ​​the three-axis AMR magnetic sensor. The formation area of ​​the Z-axis AMR magnetic sensor is located on the side of the groove and covers and extends to the substrate surface outside the groove.

7. The method for forming the MEMS three-axis AMR magnetic sensor according to claim 1, It is characterized in that The polymer in step three is generated by etching the protective layer, including the polymer formed on the sidewall of the photoresist.

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