Micromechanical component and method for its manufacture

Abstract

Micromechanical component (11, 12, 13, 14, 15) with a sensor chip (100) and a cap chip (400) connected to the sensor chip (100), wherein a cavity (210) is formed between the sensor chip (100) and the cap chip (400), wherein the sensor chip (100) has a movable element (220) arranged in the cavity (210), wherein the cap chip (400) has a wiring level (440, 460) with an electrically conductive electrode (441, 442, 461), wherein the cap chip (400) has a getter element (480) arranged in the cavity (210), wherein the getter element (480) is electrically connected to the electrode (441, 442, 461), wherein the getter element (480) has a first section (481) and a second section (482) electrically insulated from the first section (481), wherein the first section (481) is electrically connected to the electrode (441), wherein the second section (482) is electrically connected to another electrode (442).

Description

[0001] The present invention relates to a micromechanical component according to claim 1 and a method for manufacturing a micromechanical component according to claim 6. State of the art

[0002] Micromechanical sensors for measuring accelerations and angular rates are known from the prior art. It is also known to design acceleration sensors and angular rate sensors as integrated components on a single chip. Known acceleration and angular rate sensors have movable elements enclosed in at least partially evacuated cavities. A low cavity pressure is particularly desirable for angular rate sensors. It is known to equip the cavities of angular rate sensors with getter elements to achieve and maintain a low cavity pressure over the lifetime of the sensor element.

[0003] The patent application WO 2005 / 113 376 A1 discloses a MEMS device.

[0004] The patent application DE 10 2012 208 032 A1 discloses a hybrid-integrated component with a MEMS component and an ASIC component.

[0005] The patent application US 2014 / 0 150 553 A1 discloses a sensor device. Disclosure of the invention

[0006] One object of the present invention is to provide a micromechanical component. This object is achieved by a micromechanical component having the features of claim 1. A further object of the present invention is to provide a method for manufacturing a micromechanical component. This object is achieved by a method having the features of claim 6. Various embodiments are specified in the dependent claims.

[0007] A micromechanical component comprises a sensor chip and a cap chip connected to the sensor chip. A cavity is formed between the sensor chip and the cap chip. The sensor chip has a movable element arranged within the cavity. The cap chip has a wiring plane with an electrically conductive electrode. The cap chip also has a getter element arranged within the cavity. Advantageously, in this micromechanical component, the getter element can at least partially bind any gas present in the cavity, thereby ensuring a low pressure within the cavity. The wiring plane of the cap chip of the micromechanical component can advantageously serve for the electrical contacting and control of the sensor chip.

[0008] According to the invention, the getter element is electrically connected to the electrode. Advantageously, this makes it possible to set the getter element to a defined electrical potential. This advantageously reduces or avoids uncontrolled interaction between the getter element and the moving element of the sensor chip. The getter element can therefore even be used as a counter electrode for controlling and / or detecting the moving element of the sensor chip.

[0009] According to the invention, the getter element comprises a first section and a second section that is electrically insulated from the first section. The first section is electrically connected to the electrode. The second section is electrically connected to another electrode. Advantageously, this allows for particularly flexible control of the interaction between the getter element and the moving element. Furthermore, the getter element can advantageously be arranged particularly close to the moving element.

[0010] In one embodiment of the micromechanical component, the getter element is arranged at least partially opposite the moving element within the cavity. This advantageously allows the getter element to be designed with a large surface area, resulting in high sorption performance.

[0011] In one embodiment of the micromechanical component, the cap chip has a stop element. The getter element is positioned further away from the moving element than the stop element. Advantageously, this prevents the moving element from striking the getter element.

[0012] In one embodiment of the micromechanical component, the stop element is formed in an insulator plane that at least partially covers the wiring plane. Advantageously, this results in a particularly simple design of the micromechanical component.

[0013] In one embodiment of the micromechanical component, the stop element is electrically conductive. This allows the stop element to be advantageously supplied with the same electrical potential as the movable element, thus enabling the movable element to strike the stop element without force.

[0014] A method for fabricating a micromechanical device comprises steps for providing a sensor chip with a moving element, providing a cap chip with a wiring plane and an electrically conductive electrode, arranging a getter element on the cap chip, and connecting the sensor chip to the cap chip such that a cavity is formed between the sensor chip and the cap chip in which the moving element and the getter element are arranged. Advantageously, the getter element in the micromechanical device obtained by this method can create and maintain a low pressure in the cavity. The wiring plane of the cap chip can advantageously serve for electrically contacting and controlling the sensor chip of the micromechanical device obtained by the method.

[0015] According to the invention, the getter element is arranged such that it is electrically connected to the electrode. Advantageously, this makes it possible to set the getter element to a defined electrical potential in the micromechanical component obtainable by the method, thereby preventing uncontrolled electrical interaction between the getter element and the moving element of the sensor chip.

[0016] In one embodiment of the method, this includes a further step of removing a portion of an additional wiring layer and / or an insulator layer on the top side of the cap chip to form a recess. The getter element is then positioned in this recess. Advantageously, this allows the getter element to be positioned at a greater distance from the moving element. Furthermore, a stop element can advantageously be formed in the additional wiring layer and / or the insulator layer, which advantageously prevents the moving element from striking the getter element in the micromechanical component obtainable by the method.

[0017] The invention will now be explained in more detail with reference to the accompanying figures. These figures are shown schematically: Fig. 1 a cutaway side view of a micromechanical component; Fig. 2 a part of a first micromechanical component; Fig. 3 a part of a second micromechanical component; Fig. 4 a part of a third micromechanical component; Fig. 5 a part of a fourth micromechanical component; and Fig. 6 a part of a fifth micromechanical component.

[0018] Fig. Figure 1 shows a schematic cutaway side view of a micromechanical component 10. The micromechanical component 10 is a sensor element for measuring physical quantities, in particular for measuring accelerations and / or rotation rates. The micromechanical component 10 is an integrated micromechanical component in which a first sensor 200 and a second sensor 300 are integrated into the common micromechanical component 10. Each of the sensors 200, 300 of the micromechanical component 10 has micromechanical movable elements.

[0019] The micromechanical component 10 comprises a micromechanical sensor chip (MEMS chip) 100 and a cap chip 400.

[0020] The sensor chip 100 has a top surface 101 and a back surface 102 opposite the top surface 101. The sensor chip 100 has a substrate 110, which is preferably a silicon substrate and forms the back surface 102 of the sensor chip 100. Several conductive and insulating layers are arranged alternately on the substrate 110, some of which are structured and interconnected. In the simplified representation of the Fig. In Figure 1, there are two insulating layers 120, one conductive wiring layer 130, and one conductive functional layer 140. The functional layer 140 forms the top surface 101 of the sensor chip 100. The insulating layers 120 can, for example, be oxide layers. The conductive layers 130 and 140 can, for example, be polycrystalline silicon layers.

[0021] The cap chip 400 has a top surface 401 and a back surface 402 opposite the top surface 401. The cap chip 400 has at least one wiring layer and can, for example, be configured as an application-specific integrated circuit (ASIC). In this case, the cap chip 400 is preferably manufactured using a CMOS process.

[0022] The cap chip 400 has a substrate 410, which is preferably a silicon substrate. A metal oxide stack 430 with a plurality of alternating conductive and insulating layers is arranged on the substrate 410, forming the top surface 401 of the cap chip 400. Contact elements 420 are arranged on the opposite rear surface 402 of the cap chip 400, serving for the electrical contacting of the micromechanical component 10. The contact elements 420 can, for example, be designed as solder balls. The contact elements 420 are electrically conductive via through-contacts 421 extending through the substrate 410. Fig. 1 electrical circuits not shown in detail, which are integrated into the cap chip 400.

[0023] The sensor chip 100 and the cap chip 400 are connected to each other via connections 150. The top surface 401 of the cap chip 400 faces the top surface 101 of the sensor chip 100. The connections 150 can be, for example, metallic wafer bonds. In particular, the connections 150 can be, for example, eutectic bonds, such as aluminum-germanium bonds. The connections 150 can also be, for example, eutectic copper-tin bonds or thermocompressive bonds.

[0024] The connections 150 establish electrically conductive connections between the cap chip 400 and the sensor chip 100, enabling the first sensor 200 and the second sensor 300 to be controlled and read by the electrical circuits integrated in the cap chip 400. Furthermore, the connections 150 hermetically seal cavities formed between the top surface 101 of the sensor chip 100 and the top surface 401 of the cap chip 400.

[0025] The first sensor 200 can, for example, be configured as a gyroscope. The first sensor 200 has a cavity 210 formed between the top surface 101 of the sensor chip 100 and the top surface 401 of the cap chip 400. A low pressure preferably prevails in the cavity 210. A movable element 220 formed in the functional plane 140 of the sensor chip 100 is movably arranged in the cavity 210 of the first sensor 200.

[0026] The second sensor 300 can, for example, be configured as an accelerometer 300. The second sensor 300 has a cavity 310 formed between the top surface 101 of the sensor chip 100 and the top surface 401 of the cap chip 400. A low pressure also preferably prevails in the cavity 310 of the second sensor 300. However, the pressure in the cavity 310 of the second sensor 300 can be higher than the pressure in the cavity 210 of the first sensor 200. The second sensor 300 includes a movable element 320 formed in the functional plane 140 of the sensor chip 100, which is movably arranged in the cavity 310 of the second sensor 300.

[0027] To enable the formation and maintenance of a low pressure in the cavity 210 of the first sensor 200, the cap chip 400 has a getter element arranged in the cavity 210, which is located in Fig. 1 is not shown. The following will be based on the Fig. Two to six different ways of designing and arranging the getter element are shown. In each case, the getter element serves to capture gas molecules located in the cavity 210 of the first sensor 200, for example by direct chemical bonding or by sorption.

[0028] Fig. Figure 2 shows a schematic cutaway side view of part of a micromechanical component 11. The micromechanical component 11 is designed like the micromechanical component 10 of the Fig. 1. In Fig. Figure 2 shows only a part of the micromechanical component 11 in the area of ​​the first sensor 200. Fig. 2 also shows in Fig. 1. Details of the movable element 220 of the first sensor 200 that are not recognizable, one of the connections 150 between the sensor chip 100 and the cap chip 400 and the metal oxide stack 430 of the cap chip 400, which are explained below.

[0029] The movable element 220 of the first sensor 200 comprises a seismic mass 223, which is movably arranged in the cavity 210 relative to the other parts of the sensor chip 100 and to the cap chip 400. The seismic mass 223 can, for example, be movable in a direction 224 perpendicular to the top surface 101 of the sensor chip 100 and the top surface 401 of the cap chip 400. However, it is also possible to design the movable element 220 such that the seismic mass 223 is movable in another direction, for example, in a direction parallel to the top surface 101 of the sensor chip 100 and the top surface 401 of the cap chip 400. The seismic mass 223 is connected via at least one spring element 222 in a spring-elastic manner to an anchoring 221, which establishes a connection between the seismic mass 223 and the other parts of the sensor chip 100.

[0030] The metal oxide stack 430 of the cap chip 400 comprises a plurality of stacked wiring levels, spaced apart from one another by insulator levels. A top wiring level 440 is arranged on the upper surface 401 of the cap chip 400. The top wiring level 400 can, for example, be a sixth wiring level of the metal oxide stack 430. The top wiring level 400 is insulated from a second-to-top wiring level 460 of the metal oxide stack 430 by a top insulator level 450. The second-to-top wiring level 460 can, for example, be a fifth wiring level of the metal oxide stack 430. The wiring levels 440 and 460 of the metal oxide stack 430 can each be structured and subdivided into individual lateral sections.Individual sections of the individual wiring levels 440, 460 can be electrically connected to each other by through contacts 470 extending through the intermediate insulator levels 450.

[0031] The in Fig. The visible connection 150 between the sensor chip 100 and the cap chip 400 comprises a spacer element 151 formed on the sensor chip 100 and a eutectic connection between a first metallization 152 formed on the spacer element 151 and a second metallization 443 formed on the top surface 401 of the cap chip 400 in the uppermost wiring level 440. The first metallization 152 can, for example, comprise germanium. The second metallization 443 can, for example, comprise aluminum or an aluminum-copper alloy.

[0032] A first electrode 441 is formed on the upper surface 401 of the cap chip 400 in the uppermost wiring level 440. The first electrode 441 is arranged such that it is substantially opposite the seismic mass 223 of the movable element 220 of the first sensor 200 in a direction perpendicular to the upper surface 101 of the sensor chip 100 and to the upper surface 401 of the cap chip 400. The first electrode 441 can, for example, serve as a control and / or readout electrode for the movable element 220 of the first sensor 200.

[0033] Furthermore, the cap chip 400 of the micromechanical component 10 has a getter element 480 on its upper surface 401, arranged in the cavity 210 of the first sensor 200. The getter element 480 is located in a lateral area on the upper surface 401 of the cap chip 400, where the uppermost wiring level 440 has been removed. The getter element 480 is thus located laterally next to the first electrode 441 on the uppermost insulator level 450. The getter element 480 is electrically insulated from the first electrode 441 and all other sections of the uppermost wiring level 440.

[0034] Fig. Figure 3 shows a schematic cutaway side view of part of a micromechanical component 12, which, like the micromechanical component 10 of the Fig. 1 is trained. Fig. Figure 3 shows only a part of the micromechanical component 12 in the area of ​​the first sensor 200.

[0035] The micromechanical component 12 of the Fig. 3 differs from the micromechanical component 11 of the Fig. 2 by the fact that a second electrode 442, formed in the uppermost wiring level 440, is arranged on the upper surface 401 of the cap chip 400. The second electrode 442 is arranged in a lateral region of the upper surface 401 of the cap chip 400, which is approximately opposite the anchoring 221 of the movable element 220 of the first sensor 200. The first electrode 441 of the micromechanical component 11 of the Fig. 2 is in the micromechanical component 12 of the Fig. 3 not present. In the lateral section of the top surface 401 of the cap chip 400 opposite the seismic mass 223 of the movable element 220 of the first sensor 200, the uppermost wiring level 440 of the cap chip 400 is removed at the micromechanical component 12.

[0036] In the micromechanical component 12, the getter element 480 extends over a lateral section of the top surface 401 of the cap chip 400, where the uppermost wiring layer 440 is removed, and borders the uppermost insulator layer 450 in this area. Furthermore, in the micromechanical component 12, the getter element 480 extends over at least a portion of the second electrode 442. This creates an electrically conductive connection between the getter element 480 and the second electrode 442. This allows the getter element 480 to be brought to a defined electrical potential via the second electrode 442. Consequently, the getter element 480 itself can be used as an electrode, for example, to excite and / or detect movement of the movable element 220 of the first sensor 200.Alternatively, the getter element 480 can be supplied with the same electrical potential as the movable element 220 of the first sensor 200 in order to minimize electrical interaction between the getter element 480 and the movable element 220 of the first sensor 200. A further advantage of the arrangement of the getter element 480 of the micromechanical component 12 is... Fig. 3 consists in the fact that the getter element 480 can be designed with a very large area, which enables good pumping performance of the getter element 480.

[0037] Fig. Figure 4 shows a schematic cutaway side view of part of a micromechanical component 13, which is designed like the micromechanical component 10 of the Fig. 1. Fig. Figure 4 shows only one area of ​​the micromechanical component 13 surrounding the first sensor 200.

[0038] In the case of the micromechanical component 13 of the Fig. In the uppermost wiring level 440 of the cap chip 400, both the first electrode 441 and the second electrode 442 are formed. The first electrode 441 is located in a lateral section on the top surface 401 of the cap chip 400 opposite the seismic mass 223 of the movable element 220 of the first sensor 200. The second electrode 442 is located in a lateral region on the top surface 401 of the cap chip 400 opposite the anchoring 221 of the movable element 220 of the first sensor 200. The first electrode 441 and the second electrode 442 are electrically insulated from each other.

[0039] The getter element 480 exhibits the following characteristics in the micromechanical component 13: Fig. Figure 4 comprises a first section 481 and a second section 482. The first section 481 is arranged at the first electrode 441 and electrically connected to the first electrode 441. The second section 482 of the getter element 480 is arranged at the second electrode 442 and electrically connected to the second electrode 442.

[0040] In the micromechanical component 13, both sections 481, 482 of the getter element 480 can be separately supplied with electrical potentials via the first electrode 441 and the second electrode 442. This, in turn, makes it possible to create a force-free connection between the movable element 220 of the first sensor 200 and the sections 481, 482 of the getter element 480, or to use the sections 481, 482 of the getter element 480 as electrodes for controlling and / or reading the movable element 220 of the first sensor 200. In this case, the sections 481, 482 of the getter element 480 of the micromechanical component 13 have a particularly small distance from the movable element 220 of the first sensor 200, which can result in a strong interaction between the sections 481, 482 of the getter element 480 and the movable element 220 of the first sensor 200 and thus a high sensitivity.Another advantage of the getter element 480 of the micromechanical component 13 is that the getter element 480 can be designed with a large area, which can enable a high pumping performance of the getter element 480.

[0041] Fig. Figure 5 shows a schematic cutaway side view of a micromechanical component 14, which is designed like the micromechanical component 10 of the Fig. 1. Fig. Figure 5 shows only a part of the micromechanical component 14 in the area of ​​the first sensor 200.

[0042] In the micromechanical component 14, in addition to a portion of the uppermost wiring level 440, a portion of the uppermost insulator level 450 has also been removed from the top surface 401 of the cap chip 400, so that a portion of the second-highest wiring level 460 is exposed and forms a third electrode 461. The removal of a portion of the uppermost insulator level 450 creates a recess 490 on the top surface 401 of the cap chip 400. The third electrode 461 in the second-highest wiring level 460 is located at the bottom of this recess 490.

[0043] The getter element 480 is used in the micromechanical component 14 of the Fig. 5 is arranged in the recess 490 on the third electrode 461 and electrically connected to the third electrode 461. The third electrode 461 makes it possible to apply a defined electrical potential to the getter element 480.

[0044] The getter element 480 has a smaller thickness in the direction perpendicular to the top surface 401 of the cap chip 400 than the uppermost insulator layer 450. As a result, the getter element 480 is completely located within the recess 490 and does not project beyond a section of the uppermost insulator layer 450 that defines the recess 490. This section of the uppermost insulator layer 450 that defines the recess 490 thus forms a stop element 500. Both the getter element 480 and the stop element 500 are located at least partially opposite the seismic mass 223 of the movable element 220 of the first sensor 200 in the direction perpendicular to the top surface 101 of the sensor chip 100 and to the top surface 401 of the cap chip 400. The distance between the seismic mass 223 and the stop element 500 in the direction perpendicular to the top 101 of the sensor chip 100 is less than the distance between the seismic mass 223 and the getter element 480.This advantageously prevents the seismic mass 223 from unintentionally striking the getter element 480. Before the seismic mass 223 can strike the getter element 480, it is already in contact with the stop element 500.

[0045] In the micromechanical component 14, the getter element 480 has a greater distance from the movable element 220 of the first sensor 200 than in the micromechanical component 13 of the Fig. 4. As a result, there is less interaction between the getter element 480 and the movable element 220 of the first sensor 200 in the micromechanical component 14.

[0046] Fig. Figure 6 shows a schematic cutaway side view of a micromechanical component 15, which, like the micromechanical component 10 of the Fig. 1 is trained. Fig. Figure 6 shows only a part of the micromechanical component 15 in the area of ​​the first sensor 200.

[0047] In the case of micromechanical component 15, as in the case of micromechanical component 14, the Fig. 5, in addition to a part of the uppermost wiring level 440 of the cap chip 200, a part of the uppermost insulator level 450 of the cap chip 400 has also been removed, thereby forming the recess 490. The third electrode 461, formed in the second-highest wiring level 460, is arranged at the bottom of the recess 490. The getter element 480 is in turn arranged in the recess 490 on the third electrode 461 and is electrically connected to the third electrode 461.

[0048] In contrast to the micromechanical component 14 of the Fig. 5 shows the getter element 480 in the micromechanical component 15 of the Fig. 6 in a direction perpendicular to the top surface 401 of the cap chip 400, a thickness is added which is greater than the thickness of the uppermost insulator layer 450. As a result, the getter element 480 projects beyond the uppermost insulator layer 450.

[0049] On a part of the uppermost insulator plane 450 that limits the depression 490, the micromechanical component 15 forms Fig. 6. A remaining part of the uppermost wiring level 400 forms a fourth electrode 444. The fourth electrode 444 is insulated from the third electrode 461 and the getter element 480. The fourth electrode 444 and the part of the uppermost insulator level 450 that delimits the recess 490 together form the stop element 500.

[0050] Both the getter element 480 and the stop element 500 are arranged in the micromechanical component 15 in a direction perpendicular to the top surface 101 of the sensor chip 100 and to the top surface 401 of the cap chip 400, respectively, and at least partially opposite the movable element 220 of the first sensor 200. The fourth electrode 444 of the stop element 500 is located closer to the seismic mass 223 of the movable element 220 of the first sensor 200 than the getter element 480. This prevents the seismic mass 223 of the movable element 220 of the first sensor 200 from striking the getter element 480 in the micromechanical component 15.

[0051] The fourth electrode 444 of the stop element 500 of the micromechanical component 15 can be supplied with the same electrical potential as the movable element 220 of the first sensor 200. This enables force-free contact of the movable element 220 with the stop element 500.

Claims

[1] Micromechanical component (11, 12, 13, 14, 15) with a sensor chip (100) and a cap chip (400) connected to the sensor chip (100), wherein a cavity (210) is formed between the sensor chip (100) and the cap chip (400), wherein the sensor chip (100) has a movable element (220) arranged in the cavity (210), wherein the cap chip (400) has a wiring level (440, 460) with an electrically conductive electrode (441, 442, 461), wherein the cap chip (400) has a getter element (480) arranged in the cavity (210), wherein the getter element (480) is electrically connected to the electrode (441, 442, 461), wherein the getter element (480) has a first section (481) and a second section (482) electrically insulated from the first section (481), wherein the first section (481) is electrically connected to the electrode (441), wherein the second section (482) is electrically connected to another electrode (442). [2] Micromechanical component (12, 13, 14, 15) according to claim 1, wherein the getter element (480) is arranged in the cavity (210) at least partially opposite the movable element (220). [3] Micromechanical component (14, 15) according to one of the preceding claims, wherein the cap chip (400) has a stop element (500), wherein the getter element (480) is further away from the movable element (220) than the stop element (500). [4] Micromechanical component (14) according to claim 3, wherein the stop element (500) is formed in an insulator plane (450) which at least partially covers the wiring plane (460). [5] Micromechanical component (15) according to claim 3, wherein the stop element (500) is electrically conductive. [6] Method for manufacturing a micromechanical component (11, 12, 13, 14, 15) comprising the following steps: - Providing a sensor chip (100) with a moving element (220); - Providing a cap chip (400) with a wiring level (440, 460) with an electrically conductive electrode (441, 442, 461); - Arranging a getter element (480) on the cap chip (400); - Connecting the sensor chip (100) to the cap chip (400) such that a cavity (210) is formed between the sensor chip (100) and the cap chip (400) in which the movable element (220) and the getter element (480) are arranged, wherein the getter element (480) is arranged such that it is electrically conductively connected to the electrode (441, 442, 461), wherein the getter element (480) has a first section (481) and a second section (482) electrically insulated from the first section (481), wherein the first section (481) is electrically connected to the electrode (441), wherein the second section (482) is electrically connected to another electrode (442). [7] The method of claim 6, wherein the method comprises the following further step: - Removing part of another wiring plane (440) and / or an insulator plane (450) on a top surface (401) of the cap chip (400) to form a recess (490), wherein the getter element (480) is arranged in the recess (490).

Images