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DE-102024210892-A1 - MEMS device with a single-cavity MEMS element and an ASIC device

DE102024210892A1DE 102024210892 A1DE102024210892 A1DE 102024210892A1DE-102024210892-A1

Abstract

MEMS device comprising a MEMS element with one cavity, wherein the cavity is at least partially bounded by an ASIC device, wherein the ASIC device has several conductor layers stacked on top of each other along a y-direction between a top layer and a bottom layer, wherein the conductor layers are connected to circuit elements of the ASIC device and/or a sensor element and/or an actuator element of the MEMS element, wherein the ASIC device is adjacent to the cavity with its top layer, wherein the conductor layers have at least a first conductor layer and at least a second conductor layer, wherein the first conductor layer is arranged between the second conductor layer and the top layer, wherein the first conductor layer has at least one conductor, wherein the conductor has a layer stack with aluminum layer and titanium layer arranged one above the other in the y-direction, wherein the titanium layer is arranged between the second conductor layer and the aluminum layer, and wherein the titanium layer has a thickness greater than 40 nm in the y-direction, wherein the second conductor layer has a second conductor with copper, and wherein the titanium layer is intended as a getter layer for binding hydrogen, the hydrogen being supplied by the copper of the second conductor track, in particular, outgassing can occur from a copper-based body layer stack, with the titanium layer reducing or preventing the penetration of outgassing hydrogen into the cavity.

Inventors

  • Hans-Peter Waible

Assignees

  • Robert Bosch Gesellschaft mit beschränkter Haftung

Dates

Publication Date
20260513
Application Date
20241113

Claims (10)

  1. MEMS device (1) with a MEMS element (2) having a cavity (4), wherein the cavity (4) is at least partially bounded by an ASIC device (3), wherein the ASIC device (3) has several conductor layers (8, 9) arranged one above the other along a y-direction between a top layer (6) and a bottom layer (7), wherein the conductor layers (8, 9) are connected to circuit elements of the ASIC device and/or a sensor element and/or an actuator element of the MEMS element, wherein the ASIC device (3) adjoins the cavity (4) with its top layer (6), wherein the conductor layers (8, 9) have at least a first conductor layer (8) and at least a second conductor layer (9), wherein the first conductor layer (8) is arranged between the second conductor layer (9) and the top layer (6), wherein the first conductor layer (8) has at least one first conductor (11), wherein the The first conductor track (11) comprises a layer stack with an aluminum layer and a titanium layer (12) arranged one above the other in the y-direction, wherein the titanium layer (12) is arranged between the second conductor track layer (9) and the aluminum layer (13), and wherein the titanium layer (12) has a thickness greater than 40 nm in the y-direction, wherein the second conductor track layer (9) comprises a second conductor track (16) with copper, and wherein the titanium layer (12) is provided as a getter layer for binding hydrogen, wherein the hydrogen can outgas from the copper layer, and wherein the titanium layer (12) reduces or prevents the penetration of outgassing hydrogen into the cavity (4).
  2. MEMS component according to Claim 1 , wherein the titanium layer (12) of the first conductor (11) has a base area in a first xz-plane, wherein the second conductor (16) has a base area in a second xz-plane, wherein the base area of the titanium layer (12) in a perpendicular projection along the y-direction covers the base area of the second conductor (16) over at least 50% of a length of the second conductor (16) and over the entire width of the second conductor (16).
  3. MEMS device according to one of the preceding claims, wherein the second conductor layer (9) has a further second conductor layer (17) in addition to the second conductor layer (16), wherein the second conductor layer (17) has copper, wherein the second and the further second conductor layer (16, 17) are arranged laterally at a distance via an intermediate area (18), wherein the base surface of the titanium layer (12) extends in a perpendicular projection along the y-direction over the base surface of the second conductor layer (16), over the intermediate area (18) and the base surface of the further second conductor layer (17), so that the intermediate area (18) between the two second conductor layers (16, 17) is also covered against outgassing of hydrogen in the direction of the cavity (4).
  4. MEMS device according to one of the preceding claims, wherein a barrier layer (26) is provided between the cavity (4) and the first conductor layer (8), which reduces, in particular prevents, outgassing of argon from the first conductor layer into the cavity.
  5. MEMS component according to Claim 4 , wherein the barrier layer (26) comprises a silicon nitride layer, wherein the silicon nitride layer can in particular have a thickness of at least 40nm and is formed as a sputtered layer.
  6. MEMS device according to one of the preceding claims, wherein a via contact line (20) is led to the titanium layer (12), wherein the titanium layer (12) has a reduced thickness (21) in the y-direction in the region of the via contact line compared to a laterally adjacent region in the x-z plane in order to produce a reduced electrical resistance between the via contact line (20) and the aluminum layer (13), wherein in particular the reduced thickness is realized by a recess (19) in the titanium layer (12), wherein the via contact line (20) is arranged in the recess (19) of the titanium layer (12).
  7. MEMS component according to Claim 6 , wherein the via contact line (20) contains tungsten.
  8. MEMS device according to one of the preceding claims, wherein the titanium layer (12) has a thickness greater than 100 nm, in particular greater than 150 nm or greater than 180 nm.
  9. MEMS device according to one of the preceding claims, wherein a further titanium layer (14) is arranged between the aluminium layer (13) of the first conductor layer (8) and the cover layer (6), wherein the further titanium layer (14) has a thickness of less than 20 nm, in particular less than 15 nm.
  10. MEMS device according to one of the preceding claims, wherein a further first conductor layer (22) is arranged between the first conductor layer (8) and the second conductor layer (9), wherein the further first conductor layer (22) has at least one further first conductor (30), wherein the first conductor (11) has a layer stack (13) with aluminum layer and titanium layer (12) arranged one above the other along the y-direction, wherein the titanium layer (12) is located between the second conductor layer (9) and the aluminium layer (13) of the further first conductor layer (22), wherein the titanium layer has a thickness greater than 40 nm, and wherein the titanium layer is provided as a getter layer to bind hydrogen outgassing from the copper layer of the second conductor layer (9) in order to reduce or prevent the penetration of outgassing hydrogen into the cavity (4).

Description

The invention relates to a MEMS device comprising a MEMS element with a cavity, wherein the cavity is at least partially bounded by an ASIC device. Out of DE 10 2004 020 685 B3 A MEMS device with one cavity is known, wherein a getter layer is provided in the cavity to absorb certain gas molecules. State of the art Disclosure of the invention The invention consists in designing a MEMS device with a cavity, wherein an ASIC device at least partially limits the cavity, in such a way that a pressure change in the cavity due to gases diffusing out in the ASIC device is reduced, in particular avoided. The object of the invention is solved by the features of claim 1. Advantageous embodiments of the invention are specified in the dependent claims. One advantage of the proposed MEMS device is that outgassing of hydrogen from the ASIC device into the cavity of the MEMS element is reduced, and in particular avoided. This is achieved by the ASIC device having a conductor track with a titanium layer, the titanium layer being positioned between the cavity and another conductor track. The titanium layer has a thickness preferably greater than 40 nm. The second conductor track system (i.e., conductor track and insulation) has copper, or the second conductor track has copper, or is designed as a copper conductor track, from which hydrogen can outgas. Furthermore, the ASIC device can have a copper conductor stack with multiple copper conductor tracks from which hydrogen can outgas. The hydrogen that outgasses from the copper conductor track(s) and diffuses towards the cavity is at least partially, and in particular completely, bound by the titanium layer. Thus, the titanium layer acts as a getter layer for binding the hydrogen. Depending on the chosen embodiment, the titanium layer can also have greater thicknesses to adequately bind the hydrogen from the second conductor track. The titanium in the titanium layer has the property of forming hydrides, whereby hydrogen is incorporated into the titanium layer, releasing energy. The thickness and/or width of the titanium layer can be adjusted depending on the expected amount of hydrogen. Preferably, there is enough titanium to bind all the hydrogen outgassing from the at least one second conductor track or the copper conductor stack. The ASIC component is adjacent to the cavity of the MEMS element via a cover layer. Sensor elements and/or actuator elements can be arranged adjacent to or within the cavity, or connected to the cavity via a conduit. The ASIC device has several layers of conductive traces arranged one above the other between the top layer and a bottom layer. The conductive traces of these layers can be connected to circuit elements of the ASIC device and/or to sensor elements and/or actuator elements of the MEMS element. The ASIC device has a first conductive trace layer located between the top layer and the second conductive trace layer. The first conductive trace layer has at least one conductor, which is a stack of layers consisting of at least one aluminum layer and one titanium layer. The titanium layer is located between the aluminum layer and the second conductive trace layer and thus faces the second conductive trace layer. The second conductive trace layer has a second copper conductor or is designed as a copper layer. The titanium layer thus acts as a getter layer to bind hydrogen that can outgas from the copper conductor stack of the second conductive trace and diffuse towards the cavity. In this way, the penetration of outgassing hydrogen into the cavity is reduced or prevented. In one embodiment, the titanium layer has a base surface in a first xz-plane, and the second conductor has a base surface in a second xz-plane. The base surface of the titanium layer is arranged above the second conductor in a perpendicular projection along the y-direction over at least 50% of its length and, in particular, covers the entire width of the second conductor. Thus, the titanium layer of the first conductor preferably covers the entire width of the second conductor over at least 50% of its length in a perpendicular projection along the y-direction. In this way, the titanium layer of the first conductor achieves coverage of the second conductor, such that the titanium layer exhibits a relatively high efficiency as a getter layer. Depending on the chosen embodiment, the titanium layer covers more than 50% of the length of the second conductor track in the vertical projection, in particular 70% or more, and in particular 90% or more. Preferably, the titanium layer covers the entire width of the second conductor track, and in particular at least 5%, and in particular 10%, of the width of the second conductor track on each side. The more the titanium layer covers the width of the second conductor track in the vertical projection, the better the titanium layer's effectiveness as a getter layer. In a further embodiment, the second conductor layer has, in addition to the secon