Method for manufacturing a coupled wafer

Abstract

The invention relates to a method for manufacturing (200) a coupling wafer (100) having the following steps: a) providing (210) a first MEMS wafer (120) having a structure (121, 122) for an actuator (121') and / or a sensor (122'); b) independently therefrom providing (220) a substrate wafer (130); and c) connecting (240) a second side (120b) of the first MEMS wafer (120) with a first side (130a) of the substrate wafer (130). Furthermore, the invention also relates to a use of a method for manufacturing a coupling wafer.

Description

Technical Field

[0001] This invention relates to a method for manufacturing coupled wafers, and more particularly to a method for parallel manufacturing of at least two wafer modules for MEMS devices. Furthermore, this invention relates to the use of a method for manufacturing coupled wafers. Background Technology

[0002] DE 10 2020 209 934 A1 relates to a method for manufacturing micromechanical components and a corresponding micromechanical component. In this case, the micromechanical component is formed from ASIC components and MEMS components. An ultrathin MEMS component with vertically integrated ASIC components and a corresponding manufacturing method are disclosed, wherein the total stack thickness can be less than 300 µm. It is disclosed that these process steps can also be performed on a wafer basis, thus allowing the use of both MEMS wafers and ASIC wafers.

[0003] WO 2006 / 012255 A1 discloses an apparatus comprising: a first substrate; one or more microelectromechanical systems (MEMS) connected to the first substrate; a second substrate connected to the first substrate; and one or more passive components connected to the second substrate. It is disclosed that, in one embodiment variation, a MEMS wafer can be bonded to a passive component wafer. The advantage of this wafer bonding is mentioned: parallel production of the modules to be manufactured is possible.

[0004] DE 10 2016 110 862 A1 discloses a module having a lower module component and an upper module component, which are stacked on top of each other and electrically contact each other. To fabricate multiple such modules, lower and upper wafers with corresponding module components are proposed, wherein these wafers are interconnected, for example by eutectic bonding, conductive adhesive bonding, sintering, or welding, and subsequently separated. In this case, elements are embedded in the module components, which may be semiconductor chips, passive components, sensors, digital chips, or MEMS components.

[0005] KR 100 888 080 B1 relates to a method for manufacturing a micromirror array having a comb-shaped actuator and a mirror plate. Summary of the Invention

[0006] According to the present invention, a method for manufacturing coupled wafers is proposed, wherein the following method steps are performed: a) Provide a first MEMS wafer having a structure for actuators and / or sensors. b) Providing a substrate wafer independent of providing the first MEMS wafer; and c) Connect the first side of the first MEMS wafer to one side of the substrate wafer.

[0007] This creates the possibility of modularly building MEMS wafers and finally assembling the individual modules into a complete system.

[0008] In an advantageous further extension of the method proposed according to the invention, a second MEMS wafer, particularly a mirror wafer, is provided independently of providing a first MEMS wafer and a substrate wafer. This second MEMS wafer has a structure for the mirror, and a second side of the first MEMS wafer, which has a structure for actuators and / or sensors, different from the first side, is connected to one side of the second MEMS wafer. Therefore, the method proposed according to the invention can, depending on the degree of modularity, i.e., depending on the process variant, either provide a wafer process flow for a modular substrate and actuator, or a process flow for a modular substrate, actuator, and mirror.

[0009] In an advantageous configuration of the method proposed according to the invention, the connection of the first side of the first MEMS wafer to one side of the substrate wafer is performed in time before the second side of the first MEMS wafer is connected to one side of the second MEMS wafer, in particular, which is configured as a mirror wafer.

[0010] In an advantageous further extension of the solution proposed according to the invention, the respective wafers are manufactured before providing one of the wafers, namely, a first MEMS wafer configured as an actuator wafer, a substrate wafer and / or a second MEMS wafer configured as a mirror wafer, wherein the manufacture of at least two of these wafers is at least partially simultaneous, i.e., overlapped in time.

[0011] Advantageously, the method proposed according to the invention is designed such that one or more connection sites are formed by connecting a first side of the first MEMS wafer to a side of the substrate wafer, and these connection sites are suitable for conducting electrical signals.

[0012] Furthermore, the present invention relates to a method for manufacturing a MEMS chip having one or more MEMS elements, wherein the following method steps are performed: a) Fabricating a coupled wafer comprising a first MEMS wafer and a substrate wafer using the method described above; and b) Separate the coupled wafer into multiple MEMS chips.

[0013] According to the present invention, the coupled wafer is manufactured according to the above method, wherein the coupled wafer further includes a second MEMS wafer, particularly configured as a mirror wafer.

[0014] In an advantageous further extension of the above method, the structure for the actuator and / or the structure for the mirror plate is released after the coupling wafer is manufactured and before the coupling wafer is separated.

[0015] In a further advantageous extension of this method, the structure for the sensor is released prior to the separation process of the coupled wafer.

[0016] Advantages of the invention The solution proposed in this invention provides a method that significantly reduces the total turnaround time for manufacturing MMA wafers and decisively reduces the risk of low yield. MMA wafers are modularly constructed, with the individual modules assembled into a complete system at the end of the process chain. To this end, the process flow required to manufacture MMA wafers is divided into individual process flows for “substrate,” “actuator,” and “mirror” modules. These modules can thus be manufactured independently of each other by their own wafer process flows, which flow independently from one another. Mechanical connections, as well as electrical and thermal contacts, between the module wafers are achieved through wafer bonding methods, such as Si-Si, Au-Au, Al-Al, Cu-Cu, or Al-Ge layer systems. The method proposed in this invention significantly reduces the total turnaround time and significantly reduces the risk of yield loss due to the ever-increasing complexity of wafer construction. Furthermore, it is emphasized that individual process or design changes only affect one module, and therefore, faster re-production is possible.

[0017] The method proposed according to the invention expands manufacturing possibilities and the degrees of freedom in process control regarding individual wafer modules that can be manufactured independently of each other. Because different wafer modules are manufactured separately, processes that would be impossible, for example, to manufacture a second MEMS wafer, can be applied to a first MEMS wafer. For example, a metal layer, such as aluminum, can be included in the second MEMS wafer, which only withstands a moderate temperature of about 450°C, while in the first MEMS wafer, higher temperatures, such as 1100°C, are required during its manufacturing, for example, for performing an oven process and completing the module. By exemplarily selecting the bonding connection between the MEMS wafer and the second MEMS wafer, aluminum is ultimately introduced into the overall process at a temperature of 1100°C, which would be impossible with a single, non-modular wafer manufacturing process. The method proposed according to the invention, for example, can create MEMS structures that would be impossible to manufacture on a single wafer due to temperature limitations or also due to resistance to etching gases. Attached Figure Description

[0018] The embodiments of the present invention are further explained with reference to the accompanying drawings and the following description.

[0019] The attached diagram shows: Figure 1.1Coupled wafers, including a first MEMS wafer, a second MEMS wafer, and a substrate wafer. Figure 1.2 : The released coupled wafer has modules according to Figure 1A, and Figure 2 : A method for manufacturing coupled wafers.

[0020] Figure 3 : A schematic structure of a combination component for variants of a first MEMS wafer, a second MEMS wafer, and a substrate wafer. Figure 3.1 : A variant of the first implementation of coupled wafers, Figure 3.2 Another implementation variant of the coupled wafer, and Figure 3.3 : A third variant of the coupled wafer implementation. Detailed Implementation

[0021] In the following description of embodiments of the invention, the same or similar elements are identified by the same reference numerals, and in some cases, repeated descriptions of these elements are omitted. The accompanying drawings are merely schematic illustrations of the subject matter of the invention.

[0022] As can be seen from the illustration in FIG1, the coupled wafer 100 is respectively labeled with, for example, a second MEMS wafer 110, a first MEMS wafer 120 and a substrate wafer 130 arranged on top of each other, the substrate wafer having at least one wiring plane.

[0023] Patterns with different configurations are used in MEMS micromirror arrays (MMAs). These patterns are not fully functional components, but rather sub-components of the overall unit. For example, the pattern for a mirror primarily comprises the mirror portion, with all other components being dummy elements. Each pattern used is employed to evaluate sub-aspects of functionality, technical feasibility, and overall risk. Therefore, each pattern requires different functionalities, such as different wiring, line guides, and contacts extending in at least one plane.

[0024] Here, the pattern can be divided into different combinations of three main modules: a substrate, an actuator, and a mirror plate. Within these three main modules, they can be further divided into different variations, such as substrates with integrated through-silicon vias (TSVs), substrates with additional internal redistribution for ASICs without TSVs, or substrates of different thicknesses, etc. According to the present invention, by manufacturing the three main modules in parallel—a first MEMS wafer 120, a second MEMS wafer 110, and a substrate wafer 130 with at least one wiring plane—the total turnaround time is significantly reduced during manufacturing 200. Here, each of the main modules in its embodiment variations (see [reference to...]) Figures 3 to 3.3 The actuator (illustrated in the diagram) is manufactured separately and then connected, in particular, bonded, to two other main module variants according to the pattern and requirements. This connection is specifically constructed as a bonding connection. For example, different actuator design variants can be bonded to a substrate that routes electrical signals to contact pads on the wafer surface, allowing for faster and less complex electrical characterization of the actuator variants. To characterize the actuator in a target design, where the contacts are made on the back side of the wafer, the same actuator can be bonded to a substrate variant that directs electrical signals across the substrate to contact pads on the back side of the wafer. In individual applications, the connection can also be purely mechanical, and optionally, it can be conductive to electricity or heat. In principle, electrical contacts can also be introduced after the entire MEMS wafer is completed in a particular application. Different combinations of main modules can be combined with each other to flexibly produce different product variants. At the end of the process chain, release 260 is performed on, for example, a MEMS element 105 constructed as a micromirror. The partial release of wafers 110, 120, and 130 to be manufactured 260 can also be carried out during the manufacturing process.

[0025] Because the aforementioned main modules are manufactured in parallel, a significantly shortened total process time is achieved; furthermore, increased yield is achieved by reducing successive process steps. As a material bonding method, especially for bonding, those methods that establish electrical and thermal contacts in addition to mechanical connections are suitable. This type of bonding can be achieved, for example, through direct bonding in Al-Al, Au-Au, Cu-Cu, Al-Ge, or Si-Si systems.

[0026] From the basis Figure 1.1 As shown in the diagram, a coupled wafer 100 is fabricated in parallel manufacturing. Based on... Figure 1.1In the exemplary illustration, the coupled wafer 100 includes three components arranged side-by-side within the frame 144 of the MEMS chip 101: a second MEMS wafer 110, a first MEMS wafer 120, and a substrate wafer 130, each having at least one wiring plane. Three-way fabrication 200 of the coupled wafer 100 is performed using parallel fabrication. The modules are arranged substantially vertically stacked on top of each other, namely the second MEMS wafer 110, the first MEMS wafer 120, and the substrate wafer 130.

[0027] Figure 1.1 As shown, the second MEMS wafer 110 includes a first side 110a and an opposing second side 110b. A first MEMS wafer 120 disposed below it includes a first side 120a and a second side 120b, while a substrate wafer 130 disposed below the first MEMS wafer includes a first side 130a and a second side 130b. Regions 142 exist between the modules formed by the mutually stacked second MEMS wafer 110, first MEMS wafer 120, and substrate wafer 130. These regions are filled within sacrificial regions 146 during manufacturing for subsequent etching of a silicon dioxide sacrificial layer.

[0028] The second MEMS wafer 110 has structures 111 on its upper side, from which mirror surface 111' is generated (see [reference]). Figure 1.2 (See illustration). Regarding the first MEMS wafers 120, these first MEMS wafers are provided with structures 121 for actuators, from which actuators 121' are generated in subsequent steps of the method. The same applies to structures 122 for sensors, from which sensors 122' are generated in further steps of the process chain.

[0029] The substrate wafer 130 includes a substrate 131 having at least one wiring plane and metal contacts 140 disposed on a second side 130b.

[0030] Figure 1.2 The released coupled wafer 100' is shown, having three according to Figure 1.1 The module.

[0031] from Figure 1.1 and Figure 1.2 The comparison shows that it exists Figure 1.1 The sacrificial region 146 used for etching the silicon dioxide sacrificial layer is in accordance with Figure 1.2 The diagram does not exist. The step of connecting the second side 120b of the first MEMS wafer 120 to the first side 130a of the substrate wafer 130 is performed 240.

[0032] If, in addition to the first MEMS wafer 120 and the substrate wafer 130, a second MEMS wafer 110, which is specifically constructed as a mirror wafer and has a structure for the mirror 111, is used, then during the connection 250 process, the following construction is performed: for example, the second side 120b of the first MEMS wafer 120, which is different from the first side 120a, and the second side 110b of the second MEMS wafer 110 are bonded together.

[0033] From the basis Figure 2 The diagram schematically illustrates the method 200 for manufacturing the coupled wafer 100 and its main method steps. According to the method 200 for manufacturing the coupled wafer 100, a first MEMS wafer 120, specifically configured as an actuator wafer, is first provided (210), and a substrate wafer 130 is provided (220). Optionally, a second MEMS wafer 110, specifically implemented as a mirror wafer, can also be provided (230).

[0034] A connection 240 is made, specifically a bonding connection is constructed between one of the sides 120a and 120b of the first MEMS wafer 120 and one of the sides 130a and 130b of the substrate wafer 130.

[0035] Subsequently, the first MEMS wafer 120, which is particularly implemented as an actuator wafer, is optionally connected to one of the sides 110a and 110b of the second MEMS wafer 110, which is particularly implemented as a mirror wafer, via the connection 250.

[0036] Finally, as will be described below, the component in the form of a micromirror (MEMS element?) 105 of the MEMS chip 101 is released 260 before the coupling wafer 100 is separated 270.

[0037] Figure 3 A schematic diagram of the assembly component 150 is shown. Within this modularly constructed assembly component 150, various implementation variations are available for constructing each second MEMS wafer 110, first MEMS wafer 120, and substrate wafer 130. For example, first variation 110.1 and second variation 110.2 can be used for the second MEMS wafer 110.

[0038] Regarding the first MEMS wafer 120, there are three implementation variants 120.1, 120.2 and 120.3 available.

[0039] Different variants 130.1, 130.2 and 130.3 can be used for the substrate wafer 130 having at least one wiring plane.

[0040] exist Figure 3.1 ,3.2 Different implementation variations of the coupled wafer 100 are shown in the figure sequence of 3.3. Figure 3.1 For example, a coupled wafer 100 is shown, whose second MEMS wafer 110 includes a first variant 110.1. A first MEMS wafer 120 below it is used in the manner of its first variant 120.1; furthermore, according to... Figure 3.1 A first variant 130.1 of a substrate wafer 130 is mounted in the coupled wafer 100 of the schematic diagram. Conversely, Figure 3.2 An exemplary configuration of the coupled wafer 100 is shown, in which a second variant 110.2 is used as the second MEMS wafer 110, while a first variant 120.1 of the first MEMS wafer 120 is used as the first MEMS wafer 120 and a second variant 130.2 is used as the substrate wafer 130. Figure 3.3 In the third embodiment variant shown, its first variant 110.1 is used in a plane on which the second MEMS wafer 110 is arranged. A second embodiment variant 120.2 uses the first MEMS wafer 120 as the first MEMS wafer, and a third embodiment variant 130.3 uses the substrate wafer 130 as the substrate wafer. Figure 3.1 , 3.2 All examples of coupled wafer 100 of 3.3 show a substantially vertical construction.

[0041] This invention is not limited to the embodiments described herein and the aspects highlighted therein. Rather, various modifications that are within the scope of the claims and are of skill to those skilled in the art are possible.

Claims

1. A method for manufacturing (200) coupled wafers (100), comprising the following steps: a. Provide (210) a first MEMS wafer (120) having structures (121, 122) for actuators (121') and / or sensors (122'); b. Provide (220) a substrate wafer (130) independent of providing the first MEMS wafer; and c. Connect the second side (120b) of the first MEMS wafer (120) to the first side (130a) of the substrate wafer (130) in such a way as (240) to obtain a coupled wafer (100).

2. The method according to claim 1, wherein, The method includes the following additional steps: a. A second MEMS wafer (110), having a structure (111) for a mirror plate (111'), is provided (230) independently of providing (210) the first MEMS wafer (120) and providing (220) the substrate wafer (130); and b. Connect (250) the second side (120b) of the first MEMS wafer (120) that is different from the first side (120a) to the second side (110b) of the second MEMS wafer (110).

3. The method according to claim 2, wherein, In terms of timing, the first side (120a) of the first MEMS wafer (120) is connected to the first side (130a) of the substrate wafer (130) before the second side (120b) of the first MEMS wafer (120) is connected to the second side (110b) of the second MEMS wafer (110) (250).

4. The method according to any one of the preceding claims, wherein, Providing one of the wafers (110, 120, 130) of the wafers (210, 220, 230) respectively includes manufacturing the respective wafer (110, 120, 130), and the manufacturing of at least two of the wafers (110, 120, 130) overlaps in time.

5. The method according to any one of the preceding claims, wherein, By connecting (240) the first side (120a) of the first MEMS wafer (120) to the first side (130a) of the substrate wafer (130), one or more connection sites, especially bonding connections, are formed, which are suitable for conducting electrical signals.

6. The method according to any one of the preceding claims, characterized in that, The first MEMS wafer (120) is preferably constructed as an actuator wafer, and the second MEMS wafer (110) is preferably constructed as a mirror wafer.

7. A method for manufacturing a MEMS chip (101) having one or more MEMS elements (105), comprising the following steps: a. Manufacturing (200) a coupled wafer (100) comprising a first MEMS wafer (120) and a substrate wafer (130) by the method according to any one of claims 1 to 6; and b. Separate (270) the coupled wafers (100, 100') into multiple MEMS chips (101).

8. The method according to claim 7, wherein, The fabrication (200) of the coupled wafer (100) is carried out according to claim 2 and preferably according to any one of claims 3 to 6, and the coupled wafer (100) further includes a second MEMS wafer (110).

9. The method according to claim 8, wherein, After manufacturing (200) the coupling wafer (100) and before separating (270) the coupling wafer (100), the structure (121) for the actuator (121') and / or the structure (111) for the mirror plate (111') are released (260).

10. The method according to claim 9, characterized in that, The release (260), or at least partially the release (260), is performed by means of silicon dioxide or silicon dioxide sacrificial layer etching during the manufacturing process of the structure (111, 121).

11. The method according to any one of claims 8 to 10, characterized in that, Release (260) of the MEMS element (105), especially the micromirror.

12. The method according to claims 6 and 9, characterized in that, The structure (122) for the sensor (122') is released (260) before or during the separation (270) of the coupled wafer (100).

13. Use of the method for manufacturing (200) coupling wafer (100) according to any one of claims 1 to 12, wherein the coupling wafer comprises at least one first MEMS wafer (120) and a substrate wafer (130).

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