Method for manufacturing a substrate having a region mechanically decoupled from a support, method for manufacturing at least one spring, and a substrate

Abstract

A method for manufacturing a substrate including a region, which is mechanically decoupled from a support and has at least one component situated on the region; at least one recess being introduced on a front side of the substrate; an etching pattern being prepared on a back side of the substrate and etched anisotropically in such a manner, that vertical channels are produced on the back side of the substrate; and subsequently, a cavity being introduced at the back side of the substrate; the at least one recess on the front side of the substrate being connected to the cavity on the back side of the substrate; and in at least one region between the front side of the substrate and the cavity, at least two recesses or at least two segments of a recess being interconnected by at least one channel.

Claims

1. A method for manufacturing a substrate having a region, which is decoupled mechanically from a support and has at least one component situated on the region, the method comprising: introducing at least one recess on a front side of the substrate; producing an etching pattern on a back side of the substrate; producing vertical channels on the back side of the substrate by etching the etching pattern anisotropically; and producing a cavity in the substrate by etching the etching pattern at the back side of the substrate isotropically; wherein the at least one recess on the front side of the substrate is connected to the cavity on the back side of the substrate, and at least two recesses or at least two segments of a recess are interconnected in at least one region between the front side of the substrate and the cavity, by at least one channel, so that at least one spring situated between the at least two recesses or between the at least two segments of a recess is produced, the at least one spring being subdivided into at least two spring sections by the at least one channel in accordance with its vertical extension.

2. The method as recited in claim 1, wherein the support and the mechanically decoupled region are interconnected by at least one spring.

3. The method as recited in claim 1, wherein the at least one recess is introduced into the front side of the substrate, by removing material anisotropically to at least one first depth.

4. The method as recited in claim 3, wherein prior to the material removal, regions in the recess are protected from material removal by passivation.

5. The method as recited in claim 3, wherein the material removal is accomplished by an etching process.

6. The method as recited in claim 1, wherein the at least two recesses or the at least two segments of a recess are alternately interconnected by channels introduced by isotropic material removal and separated from each other by non-removed regions.

7. The method as recited in claim 1, wherein the at least one channel is produced, using at least two instances of anisotropic material removal that include widening of sidewalls.

8. The method as recited in claim 1, wherein the anisotropic etching is accomplished, using deep ion etching.

9. The method as recited in claim 1, wherein the etching pattern is deposited photolithographically.

10. A method for manufacturing at least one spring, using at least one recess in a substrate, to decouple a region mechanically from a support of the substrate, the method comprising: in a first step, introducing the at least one recess by anisotropically removing material to a first depth; in at least one second step, introducing at least one channel into the substrate, up to a second depth, by removing material isotropically at a level of the first depth, and at least two recesses or at least two segments of a recess are interconnected by the at least one channel so that at least one spring situated between the at least two recesses or between the at least two segments of a recess is produced, the at least one spring being subdivided into at least two spring sections by the at least one channel in accordance with its vertical extension; and in at least one third step, extending the at least one recess to a third depth by removing material anisotropically.

11. The method for manufacturing at least one recess as recited in claim 10, wherein the at least one second step and the at least one third step are repeated alternately, until the at least one recess is connected to the cavity of the back side of the substrate, or connected to the back side of the substrate.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 shows a schematic plan view of a substrate according to a first exemplary embodiment.

(2) FIG. 2 shows a schematic cross section A-A from FIG. 1; in addition, the figure shows a method for manufacturing a spring according to a first exemplary embodiment.

(3) FIG. 3 shows a schematic cross section A-A from FIG. 1; in addition, the figure elucidates a method for manufacturing a spring according to a second exemplary embodiment.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS

(4) In the figures, identical structural elements have, in each instance, the same reference numerals.

(5) FIG. 1 shows an exemplary embodiment of a substrate 1 according to a first exemplary embodiment. Substrate 1 includes a support 2. Support 2 forms a region of substrate 1, which is situated around a mechanically decoupled region 4. Components 6 are situated on mechanically decoupled region 4; according to the exemplary embodiment, these being piezoelectric elements 6, which may record a deformation of decoupled region 4 and generate a voltage, which is a function of a deformation of decoupled region 4. Support 2 and decoupled region 4 are set apart from each other by springs 8. Springs 8 do connect decoupled region 4 to support 2, but may compensate for and/or absorb mechanical forces. Therefore, springs 8 prevent transmission of mechanical forces and/or mechanical stress. Springs 8 are formed by recesses 12, 14 situated on both sides. Recesses 12, 14 join a front side 10 of substrate 1 visible in FIG. 1 to a back side 20 of substrate 1 not visible. Recesses 12, 14 are L-shaped, so that a recess 12, 14 forms, in each instance, a side of two springs 8. In this manner, four springs may be formed by four L-shaped recesses 12, 14. Alternatively, two or more separate recesses 12, 14 may also be used for forming a spring 8. On front side 10 of substrate 1, electrical lines 16 are situated on springs 8. According to the exemplary embodiment, electrical lines 16 are made of copper, but may be made of any conductive material or alloy, such as aluminum, silver, tin, graphite and the like. In this case, electrical lines 16 connect, in each instance, a piezoelectric element 6 to evaluation electronics, which are not shown and are situated on support 2.

(6) A schematic cross section A-A from FIG. 1 is shown in FIG. 2. In this connection, using method steps in FIGS. 2a-2c, FIG. 2 elucidates a method for manufacturing a spring 8 in a substrate 1 according to a first exemplary embodiment. According to the exemplary embodiment, substrate 1 has a cavity 22, which has been etched, using a corresponding etching pattern 24 at back side 20 of substrate 1. In FIGS. 2a and 2b, springs 8, 9 have not yet been formed, since recesses 12, 14 do not connect front side 10 to back side 20 of substrate 1. In a first step, anisotropic etchings are carried out up to a first depth, so that a first depth section of recesses 12, 14 is formed to have a horizontal, trench-shaped extension. In a second step, which is represented in FIG. 2b, an isotropic etching operation is carried out up to a second depth. In this isotropic etching operation, a channel 26 is formed, which interconnects the two recesses 12, 14 along their horizontal extension. A first spring section 8 of springs 8, 9 is formed by recesses 12, 14 and channel 26. In a third step, which is represented in FIG. 2c, channel 26 is extended by further anisotropic etching, until recesses 12, 14 interconnect front side 10 of substrate 1 and cavity 22 at back side 20 of substrate 1. Thus, a second spring section 9 of springs 8, 9 is formed by recesses 12, 14, cavity 22 and channel 26. Thus, springs 8, 9 include two spring sections 8, 9, which run parallelly along their horizontal extension and have a stiffness reduced in comparison with a comparable one-piece spring. Both spring sections 8, 9 connect support 2 to region 4 to be decoupled. According to the exemplary embodiment, region 4 to be decoupled also includes a cavity 28, which forms a diaphragm 30 on region 4 to be decoupled. Applying pressure or negative pressure to diaphragm 30 allows diaphragm 30 to deform and consequently act mechanically upon the piezoelectric elements 6 shown in FIG. 1.

(7) A schematic cross section A-A from FIG. 1 is shown in FIG. 3. In this connection, using method steps in FIGS. 3a-3c, FIG. 3 elucidates a method for manufacturing a spring 8 in a substrate 1 according to a second exemplary embodiment. In contrast to the method according to the first exemplary embodiment, the method according to the second exemplary embodiment includes, in its steps, only anisotropic material removal, which produces widening of sidewalls. In this manner, in an etching operation in the direction of back side 20 of substrate 1, the etching channel is widened conically. Through this, the widening of sidewalls may be adapted to a spacing of adjacent recesses 12, 14 in such a manner, that the etching channels connect at a first depth. A first spring section 32 of spring 8 is formed by this step. This anisotropic etching operation may now be continued in steps, until, for example, recesses 12, 14 produce a connection between front side 10 and back side 20 of substrate 1. A spring section 32, 34, 36, 38 is preferably formed in each etching operation or etching step. Using this method, a spring 8 having a plurality of spring sections 32, 34, 36, 38 may be produced. If necessary, a passivation layer, which is used as an etching mask, may be deposited onto substrate 1, that is, into recesses 12, 14 and their sidewalls, prior to each etching operation.