Inertial sensor and manufacturing method thereof
By depositing and selectively retaining the epitaxial seed layer on the sacrificial layer during the manufacturing process of inertial sensors, the problem of granular epitaxial structure at the chamfer position is solved, achieving stability of vacuum sealing and elimination of particulate contamination, thus improving product quality.
Patent Information
- Application Number
- CN202511420469.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-09-30
- Publication Date
- 2026-01-16
AI Technical Summary
During the manufacturing process of inertial sensors, irregular granular epitaxial structures appear at the chamfered edges of the chip pattern, leading to vacuum sealing failure and particle shedding, which affects product yield and reliability.
By depositing an epitaxial seed layer on the sacrificial layer and selectively retaining the epitaxial seed layer on the chamfer and back side as a mask for etching, anchor holes are formed and an epitaxial structure layer is grown, smoothing the surface morphology of the chamfer area and avoiding the formation of granular epitaxial structures.
It eliminates the risks of vacuum alarms and particulate contamination, significantly improving product yield and performance consistency.
Smart Images
Figure CN121341933A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of semiconductor manufacturing technology, and in particular to an inertial sensor and its manufacturing method. Background Technology
[0002] When fabricating inertial sensors using surface micromachining (SEM), irregular granular epitaxial structures appeared at the chamfered edges of the chip pattern during the epitaxial growth (EPI) seed layer step. This structure caused the following serious subsequent defects:
[0003] (1) Vacuum alarm: Due to the unevenness of the wafer surface caused by these granular structures, the wafer cannot be fully attached to the electrostatic chuck of the equipment in subsequent processes (such as thin film deposition or etching), resulting in vacuum seal failure, which triggers system alarm and interrupts production;
[0004] (2) Particle shedding and defects: During the removal of the sacrificial layer oxide, the oxide between these particle structures and the underlying layer is etched away, causing particle shedding. These detached particles become contaminant defects on the wafer, seriously affecting the yield and reliability of sensor products. Summary of the Invention
[0005] The purpose of this invention is to provide a method for manufacturing an inertial sensor to solve one or more problems in the prior art.
[0006] To address the above problems, the present invention provides a method for manufacturing an inertial sensor, characterized by comprising:
[0007] A substrate is provided, and an insulating dielectric layer is formed to cover the substrate;
[0008] Interconnect lines and a sacrificial layer are sequentially formed on the insulating dielectric layer, with the sacrificial layer covering the interconnect lines;
[0009] An epitaxial seed layer is deposited on the sacrificial layer;
[0010] Remove the epitaxial seed layer located on the front side of the sacrificial layer, while selectively retaining the epitaxial seed layer located at the chamfered edge and back side of the sacrificial layer;
[0011] Using the remaining epitaxial seed layer as a mask, the sacrificial layer is patterned and etched to form anchor holes;
[0012] An epitaxial structure layer is grown on the exposed sacrificial layer and on the remaining epitaxial seed layer, the epitaxial structure layer filling the anchor hole to form an anchor;
[0013] The epitaxial structure layer located on the sacrificial layer is patterned to form a movable micromechanical structure.
[0014] Optionally, in the method for manufacturing the inertial sensor, the thickness of the epitaxial seed layer is 500~8000 Å.
[0015] Optionally, in the method for manufacturing the inertial sensor, the material of the epitaxial seed layer includes at least one of monocrystalline silicon, polycrystalline silicon, amorphous silicon, and polycrystalline silicon germanium.
[0016] Optionally, in the manufacturing method of the inertial sensor, the process for forming the epitaxial seed layer includes: furnace tube low-pressure chemical vapor deposition process.
[0017] Optionally, in the manufacturing method of the inertial sensor, the process used to remove the epitaxial seed layer located on the front side of the sacrificial layer includes: chemical mechanical polishing;
[0018] The sacrificial layer is the stop layer for the chemical mechanical polishing.
[0019] Optionally, in the method for manufacturing the inertial sensor, the materials of the insulating dielectric layer and the sacrificial layer include silicon oxide.
[0020] Optionally, in the method for manufacturing the inertial sensor, the interconnecting lines are electrically connected to the substrate through vias formed in the insulating dielectric layer, and the substrate serves as the ground terminal of the circuit.
[0021] Optionally, in the method for manufacturing the inertial sensor, the process of patterning the epitaxial structure layer includes: a deep reactive ion etching process.
[0022] Optionally, in the method for manufacturing the inertial sensor, after patterning the epitaxial layer, the manufacturing method further includes:
[0023] Remove the sacrificial layer; and,
[0024] A capped wafer is provided, and the capped wafer is bonded to the substrate to form a vacuum-sealed package.
[0025] The present invention also provides an inertial sensor manufactured using the manufacturing method described in any of the preceding claims.
[0026] In summary, the inertial sensor and its manufacturing method provided by the present invention include: providing a substrate and forming an insulating dielectric layer to cover the substrate; sequentially forming interconnect lines and a sacrificial layer on the insulating dielectric layer, the sacrificial layer covering the interconnect lines; depositing an epitaxial seed layer on the sacrificial layer; removing the epitaxial seed layer located on the front side of the sacrificial layer, while selectively retaining the epitaxial seed layer located at the chamfered edge and the back side of the sacrificial layer; using the remaining epitaxial seed layer as a mask, patterning and etching the sacrificial layer to form anchor holes; growing an epitaxial structure layer on the exposed sacrificial layer and on the remaining epitaxial seed layer, the epitaxial structure layer filling the anchor holes to form anchors; and patterning the epitaxial structure layer located on the sacrificial layer to form a movable micromechanical structure. By depositing and selectively retaining the epitaxial seed layer on the sacrificial layer, the surface morphology of the chamfered region is effectively smoothed, stress concentration and abnormal nucleation points are eliminated, and the formation of granular epitaxial structures is fundamentally avoided. Therefore, the risks of vacuum alarms and particulate contamination in subsequent processes can be eliminated, and product yield and performance consistency can be significantly improved. Attached Figure Description
[0027] Figure 1 A flowchart illustrating a method for manufacturing an inertial sensor according to an embodiment of the present invention;
[0028] Figures 2-10 for Figure 1 Schematic diagrams of the device structures corresponding to each step in the process;
[0029] In the attached image:
[0030] 10 - Substrate; 20 - Insulating dielectric layer; 30 - Interconnect line; 40 - Sacrificial layer; 50 - Epitaxial seed layer; 60 - Epitaxial structure layer; 401 - Anchor hole. Detailed Implementation
[0031] The inertial sensor and its manufacturing method proposed in this invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be noted that the drawings are all in a very simplified form and use non-precise scales, used only to facilitate and clarify the illustration of the embodiments of the invention. Furthermore, the structures shown in the drawings are often part of the actual structure. In particular, different figures may emphasize different aspects and sometimes use different scales. It should be understood that relative terms such as "above," "below," "top," and "bottom" shown in the drawings can be used to describe the relationships between various elements. These relative terms are intended to cover different orientations of elements other than those depicted in the drawings. For example, if the device is inverted relative to the view in the drawings, an element described as "above" another element will now be below that element.
[0032] like Figure 1As shown, this embodiment of the invention provides a method for manufacturing an inertial sensor, comprising the following steps:
[0033] S1, providing a substrate and forming an insulating dielectric layer to cover the substrate;
[0034] S2, interconnect lines and a sacrificial layer are sequentially formed on the insulating dielectric layer, and the sacrificial layer covers the interconnect lines;
[0035] S3, deposit an epitaxial seed layer on the sacrificial layer;
[0036] S4, remove the epitaxial seed layer located on the front side of the sacrificial layer, while selectively retaining the epitaxial seed layer located at the chamfered edge and back side of the sacrificial layer;
[0037] S5, using the remaining epitaxial seed layer as a mask, the sacrificial layer is patterned and etched to form anchor holes;
[0038] S6, an epitaxial structure layer is grown on the exposed sacrificial layer and on the remaining epitaxial seed layer, the epitaxial structure layer filling the anchor hole to form an anchor;
[0039] S7, The epitaxial structure layer located on the sacrificial layer is patterned to form a movable micromechanical structure.
[0040] The manufacturing method provided in this embodiment of the invention effectively smooths the surface morphology of the chamfered region by depositing and selectively retaining the epitaxial seed layer on the sacrificial layer, eliminating stress concentration and abnormal nucleation points, and fundamentally avoiding the formation of granular epitaxial structures. Therefore, it can eliminate the risk of vacuum alarms and particulate contamination in subsequent processes, and significantly improve product yield and performance consistency.
[0041] The following combination Figures 2-10 The manufacturing method provided in the embodiments of the present invention will be further described.
[0042] First, execute step S1, as follows: Figure 2 As shown, a substrate 10 is provided, and an insulating dielectric layer 20 is formed to cover the substrate 10.
[0043] The insulating dielectric layer 20 is formed not only on the front side of the substrate 10, but also on the chamfered edge region of the substrate 10 and the back side of the substrate 10.
[0044] In this embodiment, the insulating dielectric layer 20 may optionally be made of silicon oxide. Silicon oxide has good insulation and etching selectivity, and is easily selectively removed in subsequent processes. In other embodiments, silicon nitride (Si3N4) or other dielectric materials may be used as alternatives, possessing similar insulation properties.
[0045] Next, execute step S2, such as Figure 3 As shown, interconnect lines 30 are formed on the insulating dielectric layer 20, and as shown in the figure. Figure 4 As shown, a sacrificial layer 40 is formed, which covers the interconnect line 30.
[0046] The insulating dielectric layer 20 has through holes, and the interconnecting line 30 is electrically connected to the substrate 10 through the through holes formed in the insulating dielectric layer 20. The substrate 10 serves as the ground terminal of the circuit.
[0047] In this embodiment, optionally, the sacrificial layer 40 is made of silicon oxide, which has good insulation and etching selectivity, and is easily selectively removed in subsequent processes. In other embodiments, the sacrificial layer 40 may also be made of sacrificial dielectric materials such as phosphosilicate glass (PSG) or borosilicate glass (BPSG).
[0048] Then, proceed with step S3, as follows: Figure 5 As shown, an epitaxial seed layer 50 is deposited on the sacrificial layer 40. The epitaxial seed layer 50 is formed on the front side, edge chamfer, and back side of the sacrificial layer 40.
[0049] Optionally, the material of the epitaxial seed layer 50 includes at least one of monocrystalline silicon, polycrystalline silicon, amorphous silicon, and polycrystalline silicon germanium.
[0050] Preferably, the thickness of the epitaxial seed layer 50 is 500~8000 Å. This thickness range ensures sufficient masking effect while minimizing the impact on wafer warpage, which is beneficial to the accuracy of subsequent photolithography and etching processes.
[0051] Preferably, the epitaxial seed layer 50 is formed using a furnace tube low-pressure chemical vapor deposition (LPCVD) process. The epitaxial seed layer 50 is relatively thin, and the LPCVD process can ensure good uniformity and consistency of the film.
[0052] Next, proceed to step S4, as follows: Figure 6 As shown, the epitaxial seed layer 50 located on the front side of the sacrificial layer 40 is removed, while the epitaxial seed layer 50 located on the chamfered edge and back side of the sacrificial layer 40 is selectively retained.
[0053] Preferably, the epitaxial seed layer 50 located on the front side of the sacrificial layer 40 is removed using a chemical mechanical polishing (CMP) process, with the sacrificial layer 40 serving as a stop layer for the CMP. The CMP process achieves global planarization of the front side. Thus, when the sacrificial layer 40 is subsequently etched to form anchor holes, the flat surface ensures the precision of the photolithography and etching processes, laying the foundation for reliable anchor connection.
[0054] Next, proceed to step S5, as follows: Figure 7 As shown, using the remaining epitaxial seed layer 50 as a mask, the sacrificial layer 40 is patterned and etched to form anchor holes 401; and step S6 is performed, as follows: Figure 8 As shown, an epitaxial structure layer 60 is grown on the exposed sacrificial layer 40 and on the remaining epitaxial seed layer 50, the epitaxial structure layer 60 filling the anchor hole 401 to form an anchor.
[0055] It should be noted that, since the material of the epitaxial structure layer 60 is the same as or similar to the material of the epitaxial seed layer 50, therefore, Figure 8 The text does not distinguish between the epitaxial structure layer 60 and the epitaxial seed layer 50.
[0056] like Figure 9 As shown, after forming the epitaxial structure layer 60, the process may further include processing the epitaxial structure layer 60 and the epitaxial seed layer 50 to form a bonding ring. Specifically, this includes removing the epitaxial structure layer 60 and the epitaxial neutron layer 50 located on the back side, and etching the epitaxial structure layer 60 located on the front side to form a bonding alignment structure, which may be, for example, a protrusion structure.
[0057] Finally, proceed with step S7, as follows: Figure 10 As shown, the epitaxial structure layer 60 located on the sacrificial layer 40 is graphically represented to form a movable micromechanical structure.
[0058] In this embodiment, preferably, the epitaxial structure layer 60 is patterned using a depth reactive ion etching (DRIE) process. The DRIE process can achieve precise patterning of high aspect ratio structures and is suitable for the molding of micromechanical structures. In other embodiments, other anisotropic etching methods may be used as alternatives.
[0059] Furthermore, after the epitaxial structure is patterned, the manufacturing method provided in this embodiment may further include the following steps: removing the sacrificial layer 40 to release the micromechanical structure, and providing a cap wafer, bonding the cap wafer to the substrate 10 to form a vacuum-sealed package (not shown).
[0060] Preferably, the sacrificial layer 40 can be removed using a gaseous hydrofluoric acid (VHF) release process. VHF has a high selectivity for oxides and can efficiently remove the sacrificial layer 40 without damaging the polysilicon and epitaxial structure. Wet hydrofluoric acid (HF) or vapor HF can also be used as alternative release methods.
[0061] The cap wafer serves to provide mechanical protection and maintain the device's operating environment, thereby improving the device's reliability and lifespan. The bonding process between the device wafer and the cap wafer is well known to those skilled in the art and will not be described in detail here.
[0062] In the above description, the front side of substrate 10 is the side used for bonding with the cap wafer, and the back side of substrate 10 is the side opposite to the front side of substrate 10. It can be understood that when the cap wafer is bonded to the substrate 10, the side of substrate 10 on which the micromechanical structure is formed is bonded to the substrate 10.
[0063] Furthermore, this embodiment of the invention also provides an inertial sensor, which is manufactured using the manufacturing method described in this embodiment. The chamfered area of this inertial sensor has a smooth surface and no granular epitaxial structures appear.
[0064] In summary, the inertial sensor and its manufacturing method provided by the embodiments of the present invention include: providing a substrate and forming an insulating dielectric layer to cover the substrate; sequentially forming interconnect lines and a sacrificial layer on the insulating dielectric layer, the sacrificial layer covering the interconnect lines; depositing an epitaxial seed layer on the sacrificial layer; removing the epitaxial seed layer located on the front side of the sacrificial layer, while selectively retaining the epitaxial seed layer located at the chamfered edge and the back side of the sacrificial layer; using the remaining epitaxial seed layer as a mask, patterning and etching the sacrificial layer to form anchor holes; growing an epitaxial structure layer on the exposed sacrificial layer and on the remaining epitaxial seed layer, the epitaxial structure layer filling the anchor holes to form anchors; and patterning the epitaxial structure layer located on the sacrificial layer to form a movable micromechanical structure. By depositing and selectively retaining the epitaxial seed layer on the sacrificial layer, the surface morphology of the chamfered region is effectively smoothed, stress concentration and abnormal nucleation points are eliminated, and the formation of granular epitaxial structures is fundamentally avoided. Therefore, the risks of vacuum alarms and particulate contamination in subsequent processes can be eliminated, and product yield and performance consistency can be significantly improved.
[0065] It should be noted that although the present invention has been disclosed above with reference to preferred embodiments, these embodiments are not intended to limit the present invention. For any person skilled in the art, many possible variations and modifications can be made to the technical solutions of the present invention based on the disclosed technical content, or equivalent embodiments can be modified accordingly, without departing from the scope of the present invention. Therefore, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the present invention shall still fall within the scope of protection of the present invention.
Claims
1. A manufacturing method of an inertial sensor, characterized by, The method comprises: providing a substrate and forming an insulating medium layer to cover the substrate; forming an interconnection line and a sacrificial layer on the insulating medium layer in sequence, the sacrificial layer covering the interconnection line; depositing an epitaxial seed layer on the sacrificial layer; removing the epitaxial seed layer on the front surface of the sacrificial layer while selectively retaining the epitaxial seed layer on the edge chamfer and back surface of the sacrificial layer; masking the epitaxial seed layer as a mask, and performing a patterned etching on the sacrificial layer to form an anchor hole; growing an epitaxial structure layer on the exposed sacrificial layer and on the remaining epitaxial seed layer, the epitaxial structure layer filling the anchor hole to form an anchor; performing a patterned etching on the epitaxial structure layer on the sacrificial layer to form a movable micro-mechanical structure.
2. The method of manufacturing an inertial sensor according to claim 1, wherein The thickness of the epitaxial seed layer is 3. The method of manufacturing an inertial sensor according to claim 1, wherein The material of the epitaxial seed layer comprises at least one of single crystal silicon, polycrystalline silicon, amorphous silicon, and polycrystalline silicon germanium.
4. The method of manufacturing an inertial sensor according to claim 1, wherein The process of forming the epitaxial seed layer comprises a furnace tube low pressure chemical vapor deposition process.
5. The method of manufacturing an inertial sensor according to claim 1, wherein The process of removing the epitaxial seed layer on the front surface of the sacrificial layer comprises a chemical mechanical polishing. The sacrificial layer is a stop layer for the chemical mechanical polishing.
6. The method of manufacturing an inertial sensor according to claim 1, wherein The material of the insulating medium layer and the sacrificial layer comprises silicon oxide.
7. The method of manufacturing an inertial sensor according to claim 1, wherein The interconnection line is electrically connected to the substrate through a via hole formed in the insulating medium layer, and the substrate serves as a ground terminal of the circuit.
8. The method of manufacturing an inertial sensor according to claim 1, wherein The process of patterning the epitaxial structure layer comprises a deep reactive ion etching process.
9. The method of manufacturing an inertial sensor according to claim 1, wherein After patterning the epitaxial layer, the manufacturing method further comprises: removing the sacrificial layer; and providing a cap wafer, and bonding the cap wafer with the substrate to form a vacuum hermetic package.
10. An inertial sensor, characterized by The inertial sensor is manufactured by the manufacturing method according to any one of claims 1-9.