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DE-102024210898-A1 - Method for manufacturing a MEMS component and MEMS component

DE102024210898A1DE 102024210898 A1DE102024210898 A1DE 102024210898A1DE-102024210898-A1

Abstract

The invention relates to a method for manufacturing a MEMS device (1) with a layer stack (10) of layers (12, 13, 14, 15, 16) stacked in a Z-direction (Z), wherein layers (12, 13, 14, 15, 16) of the layer stack (10) are successively deposited on a substrate (11) and, in particular lithographically, are structured in a defined orientation to a reference plane to form layer structures (122, 132, 142, 152), wherein a lower layer (12) of the layer stack (10) has at least one lower orientation marker (121) in a defined orientation to the reference plane. The lower alignment mark (121) is used to determine the orientation of the layer stack (10) with respect to the reference plane by detecting electromagnetic radiation in the infrared (IR) spectral range, in particular by detecting an infrared contrast. An upper layer (16) is provided with a surface structure (20) in a defined orientation to the reference plane, wherein the surface structure (20) has at least one upper alignment mark (321) in a defined orientation to the reference plane.

Inventors

  • Christof Schwenk
  • Andreas Finn

Assignees

  • Robert Bosch Gesellschaft mit beschränkter Haftung

Dates

Publication Date
20260513
Application Date
20241113

Claims (14)

  1. Method for fabricating a MEMS device (1) with a layer stack (10) of layers (12, 13, 14, 15, 16) stacked in a Z-direction (Z), wherein layers (12, 13, 14, 15, 16) of the layer stack (10) are successively deposited on a substrate (11) and, in particular lithographically, are structured in a defined orientation to a reference plane into layer structures (122, 132, 142, 152), wherein a lower layer (12) of the layer stack (10) has at least one lower orientation marker (121) in a defined orientation to the reference plane, characterized in that the lower orientation marker (121) is used to determine the orientation of the layer stack (10) with respect to the reference plane by detecting electromagnetic radiation in the infrared spectral range (IR), in particular by detecting a Infrared contrasts are detected and an upper layer (16) is provided with a surface structuring (20) in a defined orientation to the reference plane, wherein the surface structuring (20) of the upper layer (16) has at least one upper orientation mark (321) in a defined orientation to the reference plane.
  2. Procedure according to Claim 1 , characterized in that the surface structuring (20) forms recesses (21) for a further layer structure (171) of a further layer (17), which is subsequently deposited on the upper layer, wherein the further layer structure is formed in a defined orientation to the reference plane in the recesses (21) of the surface structuring (20).
  3. Procedure according to Claim 2 , characterized in that the at least one upper alignment mark (321) is detected to determine the orientation of the further layer structure (17) with respect to the reference plane, wherein electromagnetic radiation in the visible spectral range (VIS) is detected.
  4. Procedure according to Claim 2 or 3 , characterized in that the further layer structure (17) forms at least one bonding area (Bo), in particular bonding frame, for connecting the layer stack (10) formed on the substrate (11) to a further layer stack (50) of the MEMS device (1).
  5. Procedure according to Claim 4 , characterized in that the surface structuring (20) of the upper layer (16) has at least two areas (B1, B2, B3) offset with respect to the Z-direction (Z) and/or a lateral direction (L), which form a local variation in the height of the further layer structure (171) in the at least one bond area (Bo) in the Z-direction (Z).
  6. procedure according to one of the preceding Claims 2 until 5 , characterized in that after the formation of the further layer structure (17) a deep structuring of the upper layer (16) takes place, in particular lithographically.
  7. procedure according to one of the preceding Claims 2 until 6 , characterized in that the further layer (17) is formed by depositing, in particular sputtering, a metal layer on the surface of the upper layer (16).
  8. procedure according to one of the preceding Claims 2 until 7 , characterized in that the further layer (17) is opaque to electromagnetic radiation in the infrared spectral range (IR).
  9. procedure according to one of the preceding Claims 2 until 8 , characterized in that the depressions of the surface structuring (20) of the upper layer (16) in the Z-direction (Z) are offset from a surface of the upper layer (16) by 0.3 nm to 2500 nm, preferably approximately 500nm, particularly preferably 625nm, are arranged offset.
  10. procedure according to one of the preceding Claims 2 until 9 , characterized in that the thickness of the further layer extending in the Z direction is between 800 nm and 1800 nm, preferably about 1300 nm.
  11. procedure according to one of the preceding Claims 2 until 10 , characterized in that the upper layer is an epitaxially grown layer consisting of monocrystalline or polycrystalline silicon.
  12. Method according to one of the preceding claims, characterized in that the lower alignment marking (121) of the lower layer (12) is covered by at least one intermediate layer (13, 14, 15) when detected in the infrared spectral range (IR).
  13. Method according to one of the preceding claims, characterized in that the surface of the upper layer (16) and/or intermediate layer (13, 14, 15) is abrasively treated before the formation of the surface structuring (20) using a chemical-mechanical surface treatment.
  14. MEMS device (1) manufactured according to a method of the preceding claims.

Description

The invention relates to a method for manufacturing a MEMS component with a microelectromechanical system and the MEMS component manufactured according to the method, which can be designed, for example, as a MEMS sensor or MEMS actuator. State of the art In the fabrication of MEMS devices, a layer stack is typically formed from stacked layers, whereby the layers are successively deposited onto a substrate (also called a wafer) and structured in a defined orientation relative to each other, particularly by lithography. To ensure the predetermined orientation of the layer structures to be formed in the individual layers with respect to a reference plane, it is known to use one or more alignment markers (also called alignment structures) that are incorporated as surface structures in the substrate or in a lower layer of a layer stack already formed on the substrate. The alignment markers are structured such that the orientation of the substrate and/or a layer stack already formed on it with respect to the reference plane can be determined by optical detection of the alignment markers. In particular, in the exposure units of lithography referred to as "steppers" or "scanners," the orientation of the wafer or the layer stack is uniquely described by the alignment markers, thus enabling precise exposure of a new layer with respect to the reference plane. In this context, it is particularly well known to structure alignment markers in such a way that they generate a defined interference pattern, which is uniquely determined by the orientation of the alignment marker relative to the reference plane. Alternatively, known alignment markers can also be designed as significant surface structures, patterns, or similar features that can be optically detected with a camera. In this case, the orientation of the substrate and/or the layer stack already formed on it relative to the reference plane is typically detected using digital image processing methods, for example, by image comparison. However, the surface structures representing the alignment markers are typically covered by the successively deposited layers during the fabrication of the semiconductor device, causing them to gradually lose their visibility. In other cases, the deposited layer undergoes post-treatment, particularly chemical-mechanical processes, which flatten its topography. This makes it difficult or even impossible to align the formed layer with respect to the reference plane by optically detecting the alignment markers embedded in the layer stack. Disclosure of the invention In this context, the invention aims to provide a method for manufacturing a MEMS component, wherein the precise alignment of the layer structures to be produced in the layers, particularly by lithography, with respect to a reference plane can be ensured. The aforementioned problem is solved by the subject matter of the independent claims. Advantageous embodiments of the invention are specified in the dependent claims. A MEMS device within the scope of this disclosure is a semiconductor device with a microelectromechanical system (MEMS), which typically includes a movable structure integrated into the layered structure (also: layer stack) of the semiconductor device. To protect the movable structure, the MEMS device may optionally include a cap, which is also formed within the layered structure of the semiconductor device. The microelectromechanical system may be a physical realization of, for example, a MEMS actuator, such as a loudspeaker, or a MEMS sensor, such as a pressure, ultrasonic, and/or inertial sensor. Within the scope of this disclosure, such MEMS actuators or MEMS sensors are collectively referred to as MEMS devices. The direction of the layer sequence perpendicular to the lateral principal extent plane of the layers is also referred to within the scope of this disclosure as the Z-direction. In particular, a layer intended for the realization of the microelectromechanical system and/or an epitaxially grown layer of the layer stack may have a relatively large layer thickness. After the deposition of such a layer, it may occur that the topography of an alignment marker covered by the layer does not produce an optically recognizable profile on the top surface of the deposited layer. In this case, the alignment with respect to the reference plane can generally no longer be determined with sufficient certainty using optical methods according to known methods. The recording of the orientation structure will be determined. Within the scope of this disclosure, the optical detection of the alignment structuring shall be understood to mean the detection of the alignment mark directly or of an associated structuring formed on the top surface of the layer stack, which is caused by the topography of an underlying alignment mark. The optical detection is performed by detecting electromagnetic radiation in the visible spectral range. Within the scope of this disclosure, the visibl