Semiconductor device and method for manufacturing the same

Abstract

The present invention discloses a semiconductor device and a manufacturing method thereof. The manufacturing method of the semiconductor device according to an embodiment of the present invention includes sequentially forming a sacrificial layer and a structural layer on a substrate; and forming a metal layer on a sidewall of the sacrificial layer, wherein a stepped structure is formed on the sacrificial layer and the structural layer; and the metal layer is formed on the stepped structure by a sputtering growth method. According to the semiconductor device and the manufacturing method thereof according to an embodiment of the present invention, the sacrificial layer that is not desired to be removed is protected by the metal layer, and the coverage and density of the metal layer are good, and the protection effect is good.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor manufacturing technology, and particularly to a semiconductor device and a manufacturing method thereof. Background Art

[0002] MEMS (Micro-Electro-Mechanical System) is a product of the combination of microelectronics technology and mechanical technology, etc. It is an extension and expansion of IC process technology and also a new breakthrough in the application of microelectronics technology. MEMS and its related technologies make it possible to manufacture miniaturized and integrated functional devices such as optical, mechanical, electrical, magnetic, acoustic, and thermal devices, and create conditions for the compounding of functions.

[0003] MEMS is essentially a microelectronic system composed of micro-mechanical structures. In the microfabrication of MEMS, during the preparation of many micro-mechanical structures, the sacrificial layer in the structure needs to be removed so that the structure can move, and this action is called "release". Generally, the release process is divided into two methods: wet release and dry release.

[0004] In the prior art, a protection structure is provided on the micro-mechanical structure to protect the structure that is not desired to be released during the release process. For wet release, this kind of protection function can be achieved by covering a protective layer (a material that is not corroded by the wet solution) between the uppermost and lowermost parts of the structure to be protected to cover the sacrificial layer to be protected. The wet chemical solution has a strong etching ability, and the final release effect is also strongly related to the wetting behavior of the solution and the protective layer. The existing protection structure usually has poor coverage and compactness on the side, and the protection effect is not good.

[0005] Therefore, it is desirable to have a new semiconductor device and a manufacturing method thereof that can overcome the above problems. Summary of the Invention

[0006] In view of the above problems, the purpose of the present invention is to provide a semiconductor device and a manufacturing method thereof, so as to better protect the sacrificial layer structure that is not desired to be released.

[0007] According to one aspect of the present invention, a manufacturing method of a semiconductor device is provided, including sequentially forming a sacrificial layer and a structural layer on a substrate; and forming a metal layer on the sidewall of the sacrificial layer, wherein a step structure is formed on the sacrificial layer and the structural layer; and the metal layer is formed on the step structure by sputtering growth.

[0008] Preferably, the structural layer and / or the sacrificial layer is etched to form a step structure at the edge of the structural layer, wherein the included angle between the side surface of the sacrificial layer and the upper surface of the substrate is less than 85°; and / or the included angle between the side surface of the structural layer and the upper surface of the sacrificial layer is less than 85°.

[0009] Preferably, the material of the sacrificial layer includes at least one selected from silicon oxide, silicon nitride, and phosphosilicate glass; the material of the structural layer includes at least one selected from polysilicon, single crystal silicon, and amorphous silicon.

[0010] Preferably, after forming the sacrificial layer and the structural layer, an insulating layer is formed on the structural layer; the material of the insulating layer includes silicon nitride; the growth method of the insulating layer is low-pressure chemical vapor deposition, and the ratio is a non-silicon-rich material.

[0011] Preferably, the manufacturing method further includes etching the insulating layer to form a stepped structure at the edge of the insulating layer, wherein the included angle between the side surface of the insulating layer and the upper surface of the structural layer is less than 85°; the metal layer covers the stepped structure at the edge of the insulating layer.

[0012] Preferably, the manufacturing method further includes providing a transition layer on the insulating layer and the structural layer; and providing the metal layer above the transition layer.

[0013] Preferably, the manufacturing method further includes forming a protective layer above the metal layer, and the protective layer is used for protecting the metal layer.

[0014] According to another aspect of the present invention, there is provided a semiconductor device, including a substrate; a sacrificial layer located above the substrate; a structural layer located above the sacrificial layer; and a metal layer covering the sidewall of the sacrificial layer for protecting the sacrificial layer, wherein a stepped structure is formed between the structural layer and the sacrificial layer, and the metal layer covers the stepped structure.

[0015] Preferably, the metal layer includes a metal layer main body covering the sidewall of the sacrificial layer for protecting the sacrificial layer; and a metal layer extension part respectively connected to the metal layer main body and the substrate for isolating the liquid medicine during the release process.

[0016] Preferably, the included angle between the side surface of the sacrificial layer and the upper surface of the substrate is less than 85°.

[0017] For the semiconductor device and its manufacturing method according to the embodiments of the present invention, a metal layer is used to protect the sacrificial layer that is not desired to be removed. The coverage and compactness of the metal layer are good, and the protection effect is good.

[0018] For the semiconductor device and its manufacturing method according to the embodiments of the present invention, the metal layer is grown by sputtering, and the included angle between the side surface of the sacrificial layer and the upper surface of the substrate is less than 85°, which is beneficial to the good coverage of the metal on the side surface of the stepped structure and can obtain a better protection effect.

[0019] According to an embodiment of the present invention, a semiconductor device and a manufacturing method thereof, the metal layer includes a metal layer extension portion, which can prevent the corrosion of the bonding interface caused by the galvanic cell effect during the wet release process, thereby preventing the wet chemical solution from penetrating into the structure, and achieving a better protection effect.

[0020] According to an embodiment of the present invention, a semiconductor device and a manufacturing method thereof, the insulating layer is a nitride material of silicon, and its growth method is low-pressure chemical vapor deposition, and the ratio is a non-silicon-rich material, which has good protection effect and good comprehensive performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Through the following description of the embodiments of the present invention with reference to the drawings, the above and other objects, features, and advantages of the present invention will become more apparent. In the drawings:

[0022] Figure 1 A schematic diagram of a semiconductor device before release according to the prior art is shown;

[0023] Figure 2 A schematic diagram of a semiconductor device after release according to the prior art is shown;

[0024] Figure 3 A flowchart of the manufacturing method of a semiconductor device according to an embodiment of the present invention is shown;

[0025] Figures 4 to 6 Schematic diagrams corresponding to each step in the manufacturing method of a semiconductor device according to an embodiment of the present invention are shown;

[0026] Figure 7 A schematic diagram of a semiconductor device according to another embodiment of the present invention is shown. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0027] The various embodiments of the present invention will be described in more detail below with reference to the drawings. In each of the drawings, the same elements are denoted by the same or similar reference numerals. For clarity, the various parts in the drawings are not drawn to scale. In addition, some well-known parts may not be shown in the figures.

[0028] The specific embodiments of the present invention will be further described in detail below in conjunction with the drawings and embodiments. Many specific details of the present invention are described below, such as the structure, material, size, processing technology, and technology of components, in order to understand the present invention more clearly. However, as those skilled in the art can understand, the present invention can be implemented without these specific details.

[0029] It should be understood that when describing the structure of a component, when a layer or a region is referred to as being "above" or "over" another layer or another region, it may mean directly above the other layer or another region, or there may be other layers or regions between it and the other layer or another region. And if the component is flipped, this layer or region will be "below" or "beneath" the other layer or another region.

[0030] Taking the MEMS microphone structure as an example, the release of existing semiconductor devices will be described. However, the application scenarios of the present invention are not limited to MEMS microphones and may be other types of semiconductor devices. Figure 1 A schematic diagram of a semiconductor device before release according to the prior art is shown. Figure 2 A schematic diagram of a semiconductor device after release according to the prior art is shown. As Figure 1 and Figure 2 shown, a MEMS microphone according to the prior art includes a substrate 1, a diaphragm 2, a sacrificial layer 3, a back plate 4, and a protective layer 5 (made of a material not corroded by a wet solution) stacked in sequence from bottom to top. During the preparation process of the MEMS microphone, a part of the sacrificial layer 3 needs to be removed so that the diaphragm 2 is released (can vibrate). At least a part of the sacrificial layer 3 needs to be retained. The protective layer 5 is connected to the sacrificial layer 3 that needs to be retained and is used to protect the sacrificial layer 3 that is not desired to be released during the wet release process (i.e., Figure 2 the retained sacrificial layer 3 in Figure 2 ). As

[0031] Figure 3 shown, the retained sacrificial layer 3 is, for example, used to support and / or space the diaphragm 2 and the back plate 4. Optionally, a stepped structure is formed on the sides of the diaphragm 2, the sacrificial layer 3, and the back plate 4 stacked in sequence from bottom to top. The protective layer 5 is located on the stepped structure and is used to protect the stepped structure (the sacrificial layer 3 at the stepped structure).

[0031] Figure 3 A method flowchart of a manufacturing method of a semiconductor device according to an embodiment of the present invention is shown. As Figure 3 shown, the manufacturing method of a semiconductor device according to an embodiment of the present invention includes the following steps:

[0032] Step S101: sequentially form a sacrificial layer and a structural layer on a substrate;

[0033] A sacrificial layer and a structural layer are sequentially formed on a substrate. For example, through deposition and etching, necessary sacrificial layers and structural layers are fabricated. The structural layer can be a back plate, a diaphragm, etc. For example, a sacrificial layer is formed above the substrate, and a structural layer is formed above the sacrificial layer; a stepped structure is formed at the edge (side surface) of the sacrificial layer and the structural layer.

[0034] In an alternative embodiment of the present invention, the material of the sacrificial layer includes at least one selected from silicon oxides, silicon nitrides, PSG (Phospho-silicate Glass) materials, etc. Optionally, the material of the structural layer includes at least one selected from polysilicon, single-crystalline silicon, amorphous silicon and other materials.

[0035] Step S102: Form a metal layer on the sidewalls of the sacrificial layer.

[0036] A metal layer is formed on the sidewalls of the sacrificial layer. Among them, a stepped structure is formed on the sacrificial layer and the structural layer, and the metal layer is formed on the stepped structure by sputtering growth. Optionally, a sacrificial layer is formed on the substrate; a structural layer is formed on the sacrificial layer. When forming the structural layer on the sacrificial layer, a stepped structure is formed at the edge of the structural layer. Optionally, the sputtered-grown metal layer is wet-etched.

[0037] In an alternative embodiment of the present invention, after forming the metal layer, the sacrificial layer is released. A wet solution is used to remove the sacrificial layer; due to the presence of the metal layer, the sacrificial layer covered by the metal layer cannot come into contact with the wet solution (this part of the sacrificial layer is protected) and is preserved.

[0038] In an alternative embodiment of the present invention, the sputtered-grown and wet-etched metal layer (gold material) is used to cover between the insulating layer and the single-crystalline silicon substrate at the bottom or the amorphous silicon structural layer at the local bottom, and the bonding width between the metal layer and the bottom material (substrate) is greater than 2 μm to achieve the purpose of completely protecting the stepped structure of the sacrificial layer.

[0039] In an alternative embodiment of the present invention, the manufacturing method of the semiconductor device further includes (after forming the structural layer on the sacrificial layer), forming a stepped structure on the sacrificial layer and the structural layer; and forming the metal layer on the stepped structure by sputtering growth. Optionally, the structural layer and / or the sacrificial layer are etched so that, in the horizontal direction, the sacrificial layer at the edge is longer than the length of the structural layer, thereby forming a stepped structure at the edge of the structural layer (sacrificial layer).

[0040] In an alternative embodiment of the present invention, the structural layer and / or the sacrificial layer are etched to form a stepped structure at the edge of the structural layer. The sidewalls of the structural layer and / or the sidewalls of the sacrificial layer are etched so that the included angle between the side surface of the sacrificial layer and the upper surface of the substrate is less than 85° and / or the included angle between the side surface of the structural layer and the upper surface of the sacrificial layer is less than 85°.

[0041] In an alternative embodiment of the present invention, after forming the sacrificial layer and the structural layer, an insulating layer is formed on the structural layer. Optionally, the insulating layer does not cover the contact with the substrate (bottom material). Optionally, the material of the insulating layer includes silicon nitride. The growth method of the insulating layer is low-pressure chemical vapor deposition, and the ratio is a non-silicon-rich material.

[0042] In an alternative embodiment of the present invention, after forming the insulating layer, the insulating layer and the sacrificial layer are etched (simultaneously). During the etching process (after etching), the angle between the side surface of the sacrificial layer and the upper surface of the substrate is less than 85° (the angle α between the sacrificial layer and the side surface of the substrate is less than 85°). Optionally, after etching the insulating layer and the sacrificial layer, a stepped structure is formed on the side surfaces of the insulating layer and the sacrificial layer.

[0043] In an alternative embodiment of the present invention, the sputter-grown (and wet-etched) metal layer is covered between the insulating layer and the substrate (bottom material).

[0044] In an alternative embodiment of the present invention, the manufacturing method of the semiconductor device further includes providing a transition layer. For example, a transition layer is provided on the insulating layer and the structural layer (on the side surfaces); a metal layer is provided above the transition layer (that is, between step S101 and step S102, a transition layer is provided as a transition between the metal layer and the insulating layer and the structural layer). Optionally, the material of the transition layer includes at least one selected from metal materials such as chromium and titanium. Optionally, the transition layer is deposited on the side surfaces of the insulating layer and the structural layer by sputter growth.

[0045] In an alternative embodiment of the present invention, after forming the metal layer, a protective layer is formed above the metal layer. The protective layer is used to protect the metal layer. Optionally, a photoresist is coated on the surface of the metal layer or a silicon oxide is grown by plasma-enhanced chemical vapor deposition at a temperature less than 300 degrees to form a protective layer to protect the surface of the metal layer and prevent it from being scratched in subsequent processes.

[0046] Figures 4 to 6 The structural schematic diagrams corresponding to the respective steps in the manufacturing method of the semiconductor device according to the embodiments of the present invention are shown. The intermediate semiconductor device after forming the sacrificial layer 3, the structural layer 6, and the insulating layer 7 on the substrate 1 is as Figure 4 shown.

[0047] Specifically, the sacrificial layer 3 is located above the substrate 1. Preferably, the angle α formed between the side surface of the sacrificial layer 3 and the upper surface of the substrate 1 is less than 85°.

[0048] The structural layer 6 is located above the sacrificial layer 3. The structural layer 6 is used, for example, to implement semiconductor functions. Optionally, the structural layer 6 can be the backplate or diaphragm in a MEMS microphone, or the vibrating part in other MEMS devices. Optionally, the structural layer 6 and the sacrificial layer 3 form a stepped structure (the structural layer 6 covers the upper surface of the sacrificial layer 3, and at least a part / edge part of the upper surface of the sacrificial layer 3 is not covered by the structural layer 6). Optionally, the metal layer 8 covers the above stepped structure. Optionally, the included angle between the side surface of the structural layer 6 and the upper surface of the sacrificial layer 3 is less than 85°.

[0049] The insulating layer 7 is located above the structural layer 6. The insulating layer 7 is used, for example, for insulating the structural layer 6. Optionally, the insulating layer 7 and the structural layer 6 form a stepped structure (the insulating layer 7 covers the upper surface of the structural layer 6, and at least a part / edge part of the upper surface of the structural layer 6 is not covered by the insulating layer 7). Optionally, the metal layer 8 covers the above stepped structure. Optionally, the included angle between the side surface of the insulating layer 7 and the upper surface of the structural layer 6 is less than 85°.

[0050] The metal layer 8 is formed at parts such as the side surface of the sacrificial layer 3, and the formed structure is as Figure 5 shown.

[0051] Specifically, the metal layer 8 covers the side wall of the sacrificial layer 3 for protecting the sacrificial layer 3. Among them, the structural layer 6 and the sacrificial layer 3 form a stepped structure, and the metal layer 8 covers the stepped structure. Optionally, the metal layer 8 covers at least one of the side surface of the sacrificial layer 3, the side surface of the structural layer 6, the side surface of the insulating layer 7, and at least a part of the upper surface of the insulating layer 7.

[0052] Release the sacrificial layer 3. For example, use a wet solution to release the sacrificial layer 3, and the sacrificial layer 3 protected by the metal layer 8 will be retained. The structure after release is as Figure 6 shown.

[0053] Specifically, most of the sacrificial layer 3 is removed by the wet solution, so that the structural layer 6 can move, and the release is completed. The part covered by the metal layer 8 (especially the side wall of the sacrificial layer 3 covered by the metal layer 8) does not come into contact with the wet solution and thus is retained.

[0054] Figure 7 The figure shows a schematic structural diagram of a semiconductor device according to another embodiment of the present invention. As Figure 7 shown, the metal layer 8 of the semiconductor device according to another embodiment of the present invention includes a metal layer main body 81 and a metal layer extension part 82.

[0055] Specifically, the metal layer main body 81 covers the side wall of the sacrificial layer 3 for protecting the sacrificial layer 3.

[0056] The metal layer extension part 82 is respectively connected to the metal layer main body 81 and the substrate 1, and is used to isolate the liquid medicine during the release process. Optionally, the sum of the width of the connection part between the metal layer main body 81 and the substrate 1 and the width of the connection part between the metal layer extension part 82 and the substrate 1 is greater than 2 μm.

[0057] In an alternative embodiment of the present invention, the semiconductor device does not include the insulating layer 7. The metal layer 8 covers at least a part of the side surface of the sacrificial layer 3, the side surface of the structural layer 6, and the upper surface of the structural layer 6.

[0058] In an alternative embodiment of the present invention, the semiconductor device further includes a transition layer. The transition layer is located between the structural layer and the metal layer. Optionally, the transition layer is located above the sacrificial layer, the insulating layer, and the structural layer; the metal layer is located above the transition layer.

[0059] In an alternative embodiment of the present invention, the semiconductor device further includes a protective layer. The protective layer is located above the metal layer and is used for protecting the metal layer.

[0060] The semiconductor device and its manufacturing method according to the embodiments of the present invention have at least the following technical effects:

[0061] The semiconductor device and its manufacturing method according to the embodiments of the present invention use a metal layer to protect the sacrificial layer that is not desired to be removed. The coverage and compactness of the metal layer are good, and the protection effect is good.

[0062] Preferably, the metal layer is grown by sputtering, which is beneficial to the good coverage of the metal on the side of the step structure and can obtain a better protection effect.

[0063] Preferably, the angle between the side surface of the sacrificial layer and the upper surface of the substrate is less than 85°, which is beneficial to the good coverage of the metal layer on the side of the step structure and can obtain a better protection effect.

[0064] Specifically, if the angle between the side surface of the sacrificial layer and the upper surface of the substrate is close to 90°, or the metal layer is grown by evaporation, the growth of the metal structure on the side of the step will be poor, which may cause the disconnection of the metal interface and cause the wet-release liquid medicine to penetrate into the structure. Similarly, if a photoresist is used for covering and its side coverage is not good, there may be a gap between the photoresist and the side structure, and the wet-release liquid medicine will also penetrate into the structure through capillary action and cannot fully play a protective role.

[0065] Preferably, the bonding width between the metal layer and the substrate is greater than 2 microns (the metal layer includes the metal layer extension part), which can prevent the galvanic cell effect during the wet release process from corroding the bonding interface, thereby preventing the wet liquid medicine from penetrating into the structure and achieving a better protection effect.

[0066] Preferably, the insulating layer is a nitride material of silicon, which is grown by low-pressure chemical vapor deposition, and the ratio is a non-silicon-rich material, with good protection effect and good comprehensive performance.

[0067] Specifically, the nitride material of silicon as the insulating layer has a relatively high cost performance. If plasma-enhanced chemical vapor deposition is used, a silicon-rich material must be used. However, if this is done, when using plasma-enhanced chemical vapor deposition, the side morphology of the structure must match the gentle-slope step structure. If the step structure is too steep, a similar poor growth state of the structure on the side of the step as described above will also occur, causing the wet-release liquid medicine to penetrate into the structure, and the protection effect for application cannot be achieved. The gentle-slope step structure means that a larger chip area needs to be occupied, that is, a higher cost. On the other hand, if plasma-enhanced chemical vapor deposition is used to fabricate the nitride of silicon, a silicon-rich material ratio must be used, because otherwise, the wet-release liquid medicine will corrode the plasma-enhanced chemical vapor deposition silicon nitride material of the non-silicon-rich material significantly, and it is difficult to achieve the due protection effect. In addition, when using low-pressure chemical vapor deposition to fabricate the nitride of silicon as the insulating layer, there is also a choice of whether to use a silicon-rich material. Since the insulating effect of the insulating layer is better when using a non-silicon-rich material, and the wet-release liquid medicine corrodes the low-pressure chemical vapor deposition silicon nitride less, and the galvanic cell effect between the metal layer and the high-resistance insulating layer is not very obvious during the wet-release liquid medicine. The embodiment of the present invention takes the combination of a non-silicon-rich material and a metal as the preferred solution, with more excellent comprehensive performance.

[0068] It should be noted that in this article, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the term "comprising", "including" or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements not only includes those elements, but also includes other elements not expressly listed, or further includes elements inherent to such process, method, article or device. Without more limitations, an element defined by the statement "including a..." does not exclude the existence of additional identical elements in the process, method, article or device including the said element.

[0069] As described above with reference to the embodiments of the present invention, these embodiments do not describe all the details in detail, nor do they limit the invention to the specific embodiments described. Obviously, many modifications and variations can be made based on the above description. The present specification selects and specifically describes these embodiments in order to better explain the principles and practical applications of the present invention, so that those skilled in the art can make good use of the present invention and its modifications. The present invention is only limited by the claims and their full scope and equivalents.

Claims

1. A manufacturing method of a semiconductor device, characterized in that, comprising: successively forming a sacrificial layer and a structural layer on a substrate; after forming the sacrificial layer and the structural layer, forming an insulating layer on the structural layer; and forming a metal layer on the sidewall of the sacrificial layer, wherein, a step structure is formed on the sacrificial layer and the structural layer, and at the edge of the insulating layer; forming the metal layer on the step structure by sputtering growth, wherein, the metal layer comprises: a metal layer main body, covering the sidewall of the sacrificial layer, for protecting the sacrificial layer; and a metal layer extension part, respectively connected to the metal layer main body and the substrate, for isolating the liquid medicine during the release process.

2. The manufacturing method according to claim 1, characterized in that, etching the structural layer and / or the sacrificial layer to form a step structure at the edge of the structural layer, wherein, the included angle between the side surface of the sacrificial layer and the upper surface of the substrate is less than 85°; and / or the included angle between the side surface of the structural layer and the upper surface of the sacrificial layer is less than 85°.

3. The manufacturing method according to claim 1, characterized in that, the material of the sacrificial layer comprises at least one selected from silicon oxide, silicon nitride, and phosphosilicate glass; the material of the structural layer comprises at least one selected from polysilicon, single crystal silicon, and amorphous silicon.

4. The manufacturing method according to claim 1, characterized in that, the material of the insulating layer comprises silicon nitride; the growth mode of the insulating layer is low-pressure chemical vapor deposition, and the ratio is a non-silicon-rich material.

5. The manufacturing method according to claim 4, characterized in that, the manufacturing method further comprises: etching the insulating layer to form a step structure at the edge of the insulating layer, wherein, the included angle between the side surface of the insulating layer and the upper surface of the structural layer is less than 85°.

6. The manufacturing method according to claim 1, characterized in that, the manufacturing method further comprises: providing a transition layer on the insulating layer and the structural layer; and providing the metal layer above the transition layer.

7. The manufacturing method according to claim 1, characterized in that, the manufacturing method further comprises: forming a protective layer above the metal layer, and the protective layer is used for protecting the metal layer.

8. A semiconductor device, characterized in that, comprising: a substrate; a sacrificial layer, located above the substrate; a structural layer, located above the sacrificial layer; an insulating layer, located above the structural layer; and a metal layer, covering the sidewall of the sacrificial layer, for protecting the sacrificial layer, wherein, a step structure is formed on the structural layer and the sacrificial layer, and at the edge of the insulating layer, and the metal layer covers the step structure; the metal layer comprises: a metal layer main body, covering the sidewall of the sacrificial layer, for protecting the sacrificial layer; and a metal layer extension part, respectively connected to the metal layer main body and the substrate, for isolating the liquid medicine during the release process.

9. The semiconductor device according to claim 8, characterized in that, the included angle between the side surface of the sacrificial layer and the upper surface of the substrate is less than 85°.

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