Manufacturing process for a micromechanical pressure sensor device and corresponding micromechanical pressure sensor device

Abstract

Manufacturing process for a micromechanical pressure sensor device (100) comprising the steps: A) Providing a substrate (1) with at least one first to one fourth trench (G1; G2; G3; G4) extending parallel to each other from a front side (V1) of the substrate (1); B) Depositing a layer (S1) onto the front side (V1), whereby at least the first to fourth trenches (G1; G2; G3; G4) are closed and structuring the layer (S1), wherein contact structures (20; 30) are formed in the layer (S1) above the second and fourth trenches (G2; G4); C) at least partial oxidation (O1) of outwardly exposed side surfaces (40) of the contact structures (20; 30) and of the second and fourth trenches (G2; G4); D) Deposition and structuring of a first metallic contacting material (M1), wherein the contact structures (20; 30) are at least partially filled with the first metallic contacting material (M1); E) Opening the second trench (G2) and the fourth trench (G4) from a rear side (R1) of the substrate (1); F) Electroplating a second metallic contacting material (M2) over the back (R1) of the substrate (1) into the second and fourth trenches (G2; G4), wherein the second metallic contacting material (M2) is deposited on the oxidized side surfaces (40), thereby forming a pressure-sensitive capacitive capacitor structure (K1); and G) Opening the first trench (G1) from the front (V1) of the substrate (1), forming a pressure access (D1) for the pressure-sensitive capacitive capacitor structure (K1).

Description

[0001] The present invention relates to a manufacturing method for a micromechanical pressure sensor device and a corresponding micromechanical pressure sensor device. State of the art

[0002] Pressure sensors based on MEMS technology can include capacitive structures and / or membranes running parallel to the front of a chip. Downsizing or reducing the size of such pressure sensors presents a challenge in research and development.

[0003] Pressure sensors with parallel detection structures occupy up to more than 70% of the chip area. Minimizing these detection structures requires, in particular, a reduction in the corresponding layer thicknesses. However, reducing layer thickness in the relevant membranes is difficult, as a smaller membrane can have reduced sensitivity. This can lead to such pressure sensors not meeting the sensitivity requirements of an ASIC or a corresponding evaluation circuit.

[0004] Furthermore, the membrane sizes or structures of the pressure sensors must be varied depending on the application. This means that complex and elaborate processes are necessary for pressure sensors with a wide range of applications.

[0005] EP 0 515 416 B1 describes a method for manufacturing an integrable, capacitive pressure sensor.

[0006] Further pressure sensor devices are disclosed in the patent applications US 2013 / 0334624 A1, US 2011 / 0163395 A1, DE 10 2010 001 982 A1 and DE 603 ​​12 583 T2. Disclosure of the invention

[0007] The present invention provides a manufacturing method for a micromechanical pressure sensor device according to claim 1 and a corresponding micromechanical pressure sensor device according to claim 9.

[0008] Preferred further training courses are the subject of the respective sub-claims. Advantages of the invention

[0009] The underlying idea of ​​the present invention is to provide, in particular, pressure-sensitive capacitive capacitor structures at the substrate level using the method described herein. The pressure-sensitive capacitive capacitor structure or membrane structure extends transversely, and in particular perpendicularly, to the front surface of the substrate. The micromechanical pressure sensor device described herein thus comprises, in particular, one or a plurality of pressure-sensitive capacitive capacitor structures extending transversely, and in particular perpendicularly, to the front surface of the substrate. This makes the micromechanical pressure sensor arrangement produced or provided herein particularly space-saving.

[0010] In other words, the space required at the substrate level for fabricating the micromechanical pressure sensor device is correspondingly reduced. Furthermore, in both the method described here and the corresponding micromechanical pressure sensor device, the sensitivity of the pressure-sensitive capacitive capacitor structure depends particularly on the lateral lithographic accuracy of the process, enabling the fabrication and provision of very small micromechanical pressure sensor devices. Moreover, the micromechanical pressure sensor device described here is energy-efficient due to its capacitive principle.

[0011] By providing a vacuum between the pressure-sensitive capacitive capacitor structure produced here and the at least one pressure access point for the pressure-sensitive capacitive capacitor structure, the micromechanical pressure sensor device described here is particularly stable against mechanical stress, especially within the micromechanical pressure sensor device, which can arise from assembly and connection technology or during operation.

[0012] Furthermore, the micromechanical pressure sensor device described here can measure different pressure ranges without requiring any changes to its spatial dimensions. This results in a uniform fingerprint that can be used, for example, for an entire generation of chips.

[0013] According to one aspect of the present invention, in step A of the manufacturing process, a substrate is provided with at least one first to one fourth groove. The at least first to fourth grooves extend from a front face of the substrate parallel to each other, and are spaced apart from each other. Furthermore, the grooves described here extend transversely, in particular perpendicularly, to the front face of the substrate. The at least first to fourth grooves do not intersect within the substrate.

[0014] In step B, a layer is deposited onto the front surface of the substrate, sealing at least the first through fourth trenches. Structuring the layer creates contact structures above the second and fourth trenches. These contact structures are free of any material within the layer and expose the second and fourth trenches starting from a surface of the layer facing away from the front surface of the substrate. Specifically, the contact structures are laterally bounded by the adjacent first and third trenches and do not extend into these trenches.

[0015] In step C, the exposed outer surfaces of the contact structures, as well as the second and fourth grooves, are at least partially oxidized. This forms an electrically insulating layer that coats the surfaces and the corresponding contact structures. Furthermore, the contact structures and the second and fourth grooves are not sealed during step C. This partial oxidation can be carried out on a silicon substrate, forming silicon dioxide on the corresponding surfaces. Alternatively, the contact structures and the second and fourth grooves can be coated with a dielectric layer. Aluminum oxide, hafnium dioxide, or a nitride layer, for example, can be used for this purpose.

[0016] In step D, a first metallic contacting material is deposited and structured. The contact structures are at least partially filled with this first metallic contacting material. The first metallic contacting material can be flush with the front surface of the substrate. The first metallic contacting material is structured such that electrodes are formed above the second and fourth grooves. These electrodes serve, in particular, for the subsequent contacting of a pressure-sensitive capacitive capacitor structure. Furthermore, bond pads and metallic conductor tracks are formed on the side of the layer facing away from the front surface of the substrate. The metallic conductor tracks can, in particular, electrically insulate each other from the bond pads and connect them to the electrodes of the second and fourth grooves.This means that the contact structure above the second groove is manufactured electrically isolated from the contact structure above the fourth groove. The metallic traces in step D and the bond pads connected to them are connected to traces outside the chip area so that the first metallic contact material remains at the same electrical potential. After the electroplating process in step F, the traces outside the chip area are removed, thus ensuring that the traces within the chip area are not electrically connected to each other.

[0017] In step E, the second and fourth trenches are opened from the back side of the substrate. This opening can be achieved, in particular, by trench etching. The second and fourth trenches thus extend completely through the substrate from the front to the back. The layer deposited in step B can be understood as a load-bearing or stabilizing layer.

[0018] In step F, a second metallic contact material is electroplated onto the back of the substrate in the second and fourth grooves. This second metallic contact material is deposited on the oxidized side surfaces, forming a pressure-sensitive capacitive capacitor structure. Nickel, copper, gold, or another suitable precious metal can be used for this second metallic contact element.

[0019] In other words, the pressure-sensitive capacitive capacitor structure described here includes, in particular, the second and fourth grooves, with the third groove being formed between the second and fourth grooves. A vacuum is created in the third groove during step B of the manufacturing process. Thus, the pressure-sensitive capacitive capacitor structure can be formed vertically to the front face of the substrate using the manufacturing process described here.

[0020] In step G, the first trench is opened from the front of the substrate, creating a pressure access point for the pressure-sensitive capacitive capacitor structure. Gas can enter the first trench through this pressure access point. The gas entering the first trench deforms the vacuum in the third trench, causing a measurable current / voltage change across the pressure-sensitive capacitive capacitor structure. This current / voltage change can then be measured at the bond pads or electrodes. The pressure in the first trench, for example, can be inferred from this change. Furthermore, the pressure access point described here can be used to compensate for mechanical stress during assembly and interconnection and / or operation of the micromechanical pressure sensor device manufactured here.

[0021] According to a preferred embodiment, an N-lattice is implemented on the front face of the substrate to form at least the first to fourth trenches. The implementation of the N-lattice can be facilitated, in particular, by providing a porous silicon, so that during layer deposition, material from the layer is not deposited into at least the first to fourth trenches. Furthermore, the N-lattice promotes the formation of a hermetically sealed vacuum in the third trench.

[0022] According to a further preferred embodiment, a porous silicon is used for the substrate. This allows for the simple formation of at least the first to fourth trenches in the substrate. The APSM (Advanced Porous Silicon Membrane) method can be used, at least partially, to form the trenches described here.

[0023] According to a further preferred embodiment, evaluation electronics, for example CMOS (Complementary Metal-Oxide-Semiconductor), and / or a bipolar processor are integrated at the substrate level. For example, the substrate described here can already include the evaluation electronics and / or the bipolar processor before the grooves described here are formed. In this way, the micromechanical pressure sensor device and the evaluation electronics can be provided at the substrate level, thus eliminating the need for complex wafer-to-wafer bonding processes.

[0024] According to a further preferred embodiment, a single-crystal silicon is used for the layer. The single-crystal silicon allows at least the first to fourth grooves to be hermetically sealed. Furthermore, the material-specific properties of single-crystal silicon improve the sensitivity of the micromechanical pressure sensor device. In particular, the single-crystal silicon can be deposited with exceptional homogeneity.

[0025] According to a further preferred embodiment, the at least partially oxidized side surfaces are used for depositing the first metallic contacting material and the second metallic contacting material. This allows the first metallic contacting material and the second metallic contacting material to be deposited in a defined manner on predetermined areas for the production of the pressure-sensitive capacitive capacitor structure, whereby deposition of the first metallic contacting material into the second and fourth grooves can be prevented, in particular by smaller opening diameters.

[0026] According to a further preferred embodiment, during the deposition and structuring of the first metallic contacting material, at least some of the metallic conductor tracks are formed, and these metallic conductor tracks are used for the electroplating of the second metallic contacting material. This allows for the simultaneous fabrication of a large number of micromechanical pressure sensor devices on the substrate based on the metallic conductor tracks. Furthermore, the simultaneous electroplating of the second metallic contacting material can be implemented simply and energy-efficiently.

[0027] According to a further preferred embodiment, the metallic conductor tracks are at least partially removed after the electroplating of the second metallic contacting material. This allows individual micromechanical pressure sensor devices in the form of individual sensors to be separated from one another without having to additionally cut the metallic conductor tracks.

[0028] According to a further aspect of the present invention, a micromechanical pressure sensor device is provided. The micromechanical pressure sensor device comprises a substrate with at least one first to one fourth groove, wherein the at least first to fourth grooves extend parallel to each other from a front face of the substrate, and a vacuum is formed in the third groove. The second and fourth grooves penetrate the substrate and have a second metallic contacting material. A pressure change in the first groove can be capacitively measured by means of electrodes that are in at least partial contact with the second metallic contacting material of the first and fourth grooves.

[0029] According to a preferred embodiment, the electrodes of the second and fourth troughs extend at least partially into the second and fourth troughs and are in contact with the second metallic contacting material. This protects the pressure-sensitive capacitive capacitor structure from external influences.

[0030] According to a preferred further development, the first trench compensates for mechanical stresses arising during operation and / or functions as a pressure access point. In addition to its function as a pressure access point, the first trench is also capable of reducing or compensating for mechanical stresses. Thus, the first trench can be assigned two functions.

[0031] The features of the manufacturing process described here for the micromechanical pressure sensor device are also disclosed for the corresponding micromechanical pressure sensor device, and vice versa. Brief description of the drawings

[0032] Further features and advantages of the present invention are explained below with reference to embodiments and the figures.

[0033] They show: Fig. Figures 1A - 8A are schematic cross-sectional views to illustrate a manufacturing process for a micromechanical pressure sensor device and a corresponding micromechanical pressure sensor device according to a first embodiment of the present invention; Fig. 1B, 3B - 5B, 7B and 8B schematic supervisions corresponding to the respective Fig. 1A, 3A - 5A, 7A and 8A; Fig. 4A', Fig. 4B', Fig. 7A' Schematic enlargements of the corresponding Fig. 4A and Fig. 7A; Fig. 9 a schematic top view to illustrate a micromechanical pressure sensor device according to a second embodiment of the present invention; and Fig. 10A - 13A schematic cross-sectional views to illustrate a method for producing an exemplary first trench and an exemplary second trench based on an APSM technology, wherein Fig. 10B - 13B corresponding supervisors of the Fig. 10A - 13A are. Embodiments of the invention

[0034] In the figures, identical reference symbols denote identical or functionally equivalent elements.

[0035] The steps of the manufacturing process for a micromechanical pressure sensor device shown in the figures depict at least one first through fifth groove G1; G2; G3; G4; G5. This is to be understood as a further embodiment of the micromechanical pressure sensor device. The symmetrical design of the first groove G1 and the fifth groove G5 allows for a more homogeneous pressure measurement. Furthermore, mechanical stress during operation of the micromechanical pressure sensor device can be compensated for more homogeneously.

[0036] Fig. Figures 1A-8A are schematic cross-sectional views to illustrate a manufacturing process for a micromechanical pressure sensor device and a corresponding micromechanical pressure sensor device according to a first embodiment of the present invention.

[0037] In Fig. 1A designates reference symbol 1 as a substrate with at least one first to one fifth trench G1; G2; G3; G4; G5. The trenches G1; G2; G3; G4; G5 extend parallel to each other from a front face V1 of the substrate 1. As in Fig. 1A and Fig. As shown in Figure 1B, at least the first to fifth trenches G1, G2, G3, G4, and G5 are freely accessible from the front face V1 of substrate 1. In particular, an N-grid N1 can be implemented on the front face V1 of substrate 1 (see Figure 1B). Fig. 10A - 13A).

[0038] In Fig. Reference numeral 2A denotes an alternative substrate 1' which has evaluation electronics A1 on its front side. Alternatively, the evaluation electronics A1 can be combined with a bipolar processor A1' or replaced by the bipolar processor A1'.

[0039] As in Fig. 3A and Fig. As shown in Figure 3B, a layer S1 is deposited onto the front surface V1 of substrate 1. This process seals at least the first to fifth trenches G1, G2, G3, G4, and G5. In this context, "sealing" can also be understood as a hermetic sealing of at least the first to fifth trenches G1, G2, G3, G4, and G5.

[0040] As in Fig. 4A and Fig. As shown in Figure 4B, layer S1 is structured, with contact structures 20; 30 being formed in layer S1 above the second and fourth trenches G2; G4.

[0041] Fig. 4A' is a corresponding enlargement of the Fig. 4A. As in Fig. As shown in Figure 4A', the contact structures 20; 30 are formed above the second and fourth trenches G2; G4 in such a way that the contact structures 20; 30 do not extend into the first trench G1, third trench G3 and fifth trench G5.

[0042] Fig. 4B' shows a further magnification of the Fig. 4A' (represented by the oval circle in the area of ​​the fourth trench G4 of the Fig. 4 A').

[0043] Fig. Figure 4B' shows a corresponding outwardly free-standing side surface 40 of the contact structures 20; 30 as well as of the second and fourth trenches G2; G4. For example, the oxide layer formed on the side surfaces 40 of the contact structures 20; 30 as well as of the second and fourth trenches G2; G4 can be silicon dioxide.

[0044] As in Fig. Figure 5A shows the deposition and structuring of a first metallic contacting material M1. The contact structures 20 and 30 are at least partially filled with this first metallic contacting material M1.

[0045] As in Fig. 5A and Fig. As shown in Figure 5B, after deposition of the first metallic contacting material M1, at least partially metallic conductor tracks LB1 are formed, which can be used for the subsequent electroplating of a second metallic contacting material M2. Furthermore, during the structuring of the first metallic contacting material M1, bond pads P1 and electrodes E2 and E4 are formed on layer S1. The conductor tracks LB1 are electrically insulated from each other and each contact the electrodes E2 and E4, which are produced during the structuring of the first metallic contacting material M1.

[0046] As in Fig. As shown in Figure 6A, the second trench G2 and the fourth trench G4 are opened from the back side R1 of substrate 1. This can be achieved, in particular, by trench etching. In other words, the first trench G1, the third trench G3, and the fifth trench G5 remain closed or have a vacuum.

[0047] As in Fig. 7A or Fig. As shown in Figure 7A', a second metallic contacting material M2 is electroplated over the back side R1 of the substrate 1 into the second and fourth grooves G2 and G4. The second metallic contacting material M2 is deposited on the oxidized side surfaces 40 (see also...). Fig. 4B'), thereby forming a pressure-sensitive capacitive capacitor structure K1.

[0048] As in Fig. As shown in Figure 7B, the contact structures 20; 30 of the second trench and the fourth trench G4 are electrically separated from each other.

[0049] As in Fig. As shown in Figure 8A, the first trench G1 and the fifth trench G5 are opened from the front face V1 of the substrate 1, forming pressure access points D1; ​​D5 for the pressure-sensitive capacitive capacitor structure K1.

[0050] As in Fig. As shown in Figure 8B, the corresponding pressure ports D1; ​​D5 run above the first trench G1 and the fifth trench G5 and parallel and spaced apart from the pressure-sensitive capacitive capacitor structure K1, with the pressure-sensitive capacitive capacitor structure K1 being located between the pressure ports D1; ​​D5.

[0051] Fig. Figure 9 is a schematic top view to illustrate a micromechanical pressure sensor device according to a second embodiment of the present invention.

[0052] As in Fig. As shown in Figure 9, the micromechanical pressure sensor device 100 has four pressure-sensitive capacitive capacitor structures K1, K2, K3, and K4 connected in series. Each of the four pressure-sensitive capacitive capacitor structures K1, K2, K3, and K4 includes corresponding pressure ports D1 and D5.

[0053] It goes without saying that the manufacturing process described here can be used in particular for the production of micromechanical pressure sensor devices with a large number of pressure-sensitive capacitive capacitor structures connected in series and / or parallel.

[0054] Fig. Figures 10A-13A are schematic cross-sectional views to illustrate a method for producing an exemplary first trench and an exemplary second trench based on an APSM technology according to the first or second embodiment of the present invention, wherein Fig. 10B - 13B corresponding supervisors of the Fig. 10A - 13A are.

[0055] Fig. Figure 10A shows a substrate 1 with a front face V1, where the N-grid N1 has been implemented on the front face V1.

[0056] To provide the first trench G1 and the second trench G2, the front face is pre-structured accordingly (notches 60), so that as in Fig. Figure 12A shows that macroscopic pores or grooves are formed transversely or, in particular, perpendicularly to the front face V1 of the substrate by means of anodizing. In particular, material residues 70 of the substrate 1 can remain.

[0057] As in Fig. As shown in Figure 13A, these material residues 70 can be removed by oxidation or, accordingly, by sintering, if these material residues 70' are thin enough (see transition from Fig. 13A to Fig.°14A). However, areas with material residues 70, which have corresponding wall thicknesses, are spared and form the first trench G1 and the second G2.

[0058] As in Fig. As shown in Figure 14A, the substrate 1, which is provided for the manufacturing process described here for the micromechanical pressure sensor device 100, comprises the N-grid N1 and, by way of example, the first trench G1 and the second trench G2. Fig. Figures 10B to 14B show corresponding top views of the schematic side views.

[0059] In other words, the construction of the trenches is based primarily on the ASPM method.

[0060] The micromechanical sensor device described here can measure pressures of approximately 1000 millibar. This pressure range is particularly interesting for customer applications.

[0061] Although the present invention has been described with reference to preferred embodiments, it is not limited thereto. In particular, the materials and topologies mentioned are only examples and are not limited to the examples described.

Claims

Manufacturing process for a micromechanical pressure sensor device (100) comprising the steps: A) Providing a substrate (1) with at least one first to one fourth spaced-apart grooves (G1; G2; G3; G4) extending parallel to each other from a front face (V1) of the substrate (1); B) Depositing a layer (S1) onto the front face (V1), wherein the at least first to fourth grooves (G1; G2; G3; G4) are closed and structuring the layer (S1), wherein contact structures (20; 30) are formed in the layer (S1) above the second and fourth grooves (G2; G4); C) Oxidizing (O1) at least partially of outwardly exposed side surfaces (40) of the contact structures (20; 30) and of the second and fourth grooves (G2; G4); D) Depositing and structuring a first metallic contacting material (M1), wherein the contact structures (20; 30) be filled at least partially with the first metallic contacting material (M1);E) Opening the second trench (G2) and the fourth trench (G4) from a rear side (R1) of the substrate (1); F) Electroplating a second metallic contacting material (M2) from the rear side (R1) of the substrate (1) into the second and fourth trenches (G2; G4), wherein the second metallic contacting material (M2) is deposited on the oxidized side faces (40), forming a pressure-sensitive capacitive capacitor structure (K1); and G) Opening the first trench (G1) from the front side (V1) of the substrate (1), forming a pressure access (D1) for the pressure-sensitive capacitive capacitor structure (K1). Manufacturing method according to claim 1, wherein an N-grid (N1) is implemented on the front side (V1) of the substrate (1) for forming the at least first to fourth trenches (G1; G2; G3; G4). Manufacturing method according to claim 1 or 2, wherein a porous silicon is used for the substrate (1). Manufacturing method according to claim 1, wherein an evaluation electronics (A1) and / or a bipolar processor (A1') is integrated at substrate level in the substrate (1). Manufacturing method according to claim 1, wherein a single-crystal silicon is used for the layer (S1). Manufacturing method according to claim 1, wherein the at least partially oxidized side surfaces (40) are used for depositing the first metallic contacting material (M1) and the second metallic contacting material (M2). Manufacturing method according to claim 1, wherein, during the deposition and structuring of the first metallic contacting material (M1), at least partially metallic conductor tracks (LB1) are formed and the metallic conductor tracks (LB1) are used for the electroplating deposition of the second metallic contacting material (M2). Manufacturing method according to claim 7, wherein the metallic conductor tracks (LB1) are at least partially removed after the electroplating of the second metallic contacting material (M2). Micromechanical pressure sensor device (100) comprising: a substrate (1) comprising at least one first to one fourth trench (G1; G2; G3; G4), wherein the at least first to fourth trenches (G1; G2; G3; G4) extend parallel to each other from a front face (V1) of the substrate (1), wherein a vacuum is formed in the third trench (G3); and wherein the second trench (G2) and the fourth trench (G4) penetrate the substrate (1) and comprise a second metallic contacting material (M2), and a pressure change in the first trench (G1) can be capacitively measured by means of electrodes (E2; E4). Micromechanical pressure sensor device (100) according to claim 9, wherein the substrate comprises evaluation electronics (A1). Micromechanical pressure sensor device (100) according to claim 9, wherein the electrodes (E2; E4) of the second trench (G2) and the fourth trench (G4) project at least partially into the second and fourth trench (G2; G4) and are in contact with the second metallic contacting material (M2). Micromechanical pressure sensor device (100) according to claim 9, wherein the first trench (G1) compensates for mechanical stress arising from assembly and connection technology and / or during operation and / or functions as a pressure access (D1).

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