JP3435647B2 - Manufacturing method of vibration type semiconductor sensor - Google Patents

Description

Description: BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] The present invention relates to a method of manufacturing a vibration type semiconductor sensor such as an acceleration sensor or a micro gyro manufactured by processing and forming a semiconductor substrate by an etching technique. is there. 2. Description of the Related Art FIG. 2 (a) shows an example of a microgyro which is a vibration type semiconductor sensor, and FIG. 2 (b) shows an AA portion shown in FIG. 2 (a). Is shown in cross section. As shown in FIGS. 2A and 2B, a support 2 (2a, 2b) is fixedly formed on a base 1 made of a glass substrate, and the support 2a, 2b is The movable portion 3 commonly connected via the beam portion 22 is formed. The movable portion 3 has comb-shaped movable electrodes 4 extending from both side surfaces thereof.
The movable electrode section 20 is constituted by. A concave portion 5 is formed on the surface of the base 1 facing the movable electrode portion 20,
The movable electrode section 20 is supported by the support section 2 via the beam section 22 in a state of being separated from the base 1. A detection electrode 6 is formed on the bottom surface of the concave portion 5 of the base 1 so as to face the movable portion 3 via a gap. As described above, since the concave portion 5 is formed on the surface of the base 1 facing the movable electrode portion 20, the movable electrode portion 20 can be displaced in the z direction shown in FIG. . Further, since the beam portion 22 is formed to extend in the y-axis direction, the movable electrode portion 20 can be displaced in the x direction shown in FIG. [0004] A fixing portion 7 (7
a, 7b) are fixedly formed, and the fixed portion 7 is formed with a comb-shaped fixed electrode 8 extending so as to mesh with the movable electrode 4, and the electrode surface of the movable electrode 4 and the fixed electrode 8 are fixed.
Are opposed to each other via a gap. The fixed part 7 and the fixed electrode 8 constitute a fixed electrode part 21. Further, on the base 1, a lead conductor 10 which is electrically connected to each of the movable electrode 4 and the detection electrode 6 is formed, and an electrode pad 11 which is connected to the leading end side of the lead conductor 10 is formed. I have. The electrode pad 11 is also formed on the fixed part 7. The support 2, movable section 3, movable electrode 4, fixed section 7, fixed electrode 8, and beam section 22 are made of low-resistance silicon (for example, polysilicon). The vibration type semiconductor sensor shown in FIG. 2 is constructed as described above. For example, each electrode pad 11 is conductively connected to a predetermined connecting portion (not shown), and is fixed to the movable electrode 4. When the electrode 8 is connected to voltage applying means (not shown) through the electrode pad 11 and the lead conductor 10 and an AC voltage is applied between the movable electrode 4 and the fixed electrode 8,
An electrostatic force is generated between the movable electrode 4 and the fixed electrode 8, and the electrostatic force causes the movable electrode portion 20 (the movable portion 3 and the movable electrode 4) to vibrate in the x direction indicated by the arrow A in FIG. I do. If the angular velocity acts on the vibrating semiconductor sensor with the y axis as the central axis in the state of the excitation vibration as described above, a direction orthogonal to both the excitation vibration direction and the central axis direction (z direction). ) Generates Coriolis force. The movable electrode section 20 detects and vibrates in the z direction due to the Coriolis force, and the capacitance between the movable section 3 and the detection electrode 6 is changed by the detected vibration. A change in the capacitance between the movable part 3 and the detection electrode 6 is input to a capacitance-voltage conversion circuit (not shown) via the lead conductor 10 and the electrode pad 11 and converted into a voltage.
It is possible to detect the magnitude of the rotational angular velocity around the y-axis based on the detected voltage. An example of a method of manufacturing the vibration type semiconductor sensor having the above configuration will be described with reference to FIGS. 3 and 4 show an example of a manufacturing process of the vibration type semiconductor sensor shown in FIG. 2 by a cross section taken along the line AA in FIG. 2 (a). As shown in FIG. 4A, a concave portion 5 facing the movable electrode portion 20 is previously formed on the surface of the base 1 made of a glass substrate, and thereafter, as shown in FIG. As shown, a detection electrode 6 is formed on the bottom surface of the recess 5 and
A lead conductor 10 and an electrode pad 11 are formed on the surface of the base 1. Then, as shown in FIG. 3A, a first semiconductor substrate 12 composed of a silicon substrate and a second semiconductor substrate 13 composed of a silicon substrate are formed of silicon oxide. A bonding substrate body 15 is formed by joining and integrating via an etching stop layer 14, and the supporting portion 2, the movable electrode portion 20, the fixed electrode portion 21, and the beam portion are formed on the surface of the first semiconductor substrate 12 of the bonding substrate body 15. A mask (for example, a nitride film (not shown)) that defines an area where 22 is to be formed is covered. Thereafter, anisotropic etching is performed from the surface side of the first semiconductor substrate 12 with a KOH aqueous solution to obtain a structure shown in FIG.
(B), the movable electrode part 20 and the fixed electrode part 2
1 is removed by etching until the partition region 16 that defines the first region 1 and the region 17 that follows the support portion 2, the fixed portion 7 of the fixed electrode portion 21, and the beam portion 22 reach the etching stop layer 14,
Support part 2, movable electrode part 20, fixed electrode part 21, beam part 22
Is formed. The KOH aqueous solution etches the first semiconductor substrate 12, which is a silicon substrate, in the depth direction and does not erode the etching stop layer 14, which is a silicon oxide layer.
Stop the etching with the H aqueous solution. Next, the mask on the first semiconductor substrate 12 is removed, and as shown in FIG. 3C, the movable electrode section 20 is aligned with the concave portion 5 of the base 1 shown in FIG. Then, the bonding substrate body 15 is arranged on the base 1, and the support 2 and the fixing part 7 of the fixed electrode part 21 are brought into contact with the base 1 and fixed by anodic bonding. Then, etching is performed from the front surface side of the second semiconductor substrate 13 to remove all the second semiconductor substrate 13 as shown in FIG. 3D, and thereafter, (FIG. As shown in e), the etching stop layer 14 is removed, the movable electrode section 20 and the fixed electrode section 21 are separated, and the vibration type semiconductor sensor is completed. However, in the method of manufacturing the vibration type semiconductor sensor, after the base 1 and the bonding substrate 15 are bonded, as shown in FIG. Since the second semiconductor substrate 13 is entirely removed, there is a problem that the number of defective products increases and the yield of the vibration type semiconductor sensor decreases. Because, as mentioned above,
When the second semiconductor substrate 13 is completely removed, the etching stop layer 1 formed at the bonding interface with the first semiconductor substrate 12 is formed.
In many cases, the stress 4 causes the etching stop layer 14 to warp and lift the support portion 2 and the fixing portion 7, and the support portion 2 and the fixing portion 7 come off the base 1 in many cases. That is, the yield of the type semiconductor sensor is reduced. SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to provide a method of manufacturing a vibration type semiconductor sensor capable of improving the yield. Means for Solving the Problems In order to achieve the above object, the present invention has the following structure to solve the above problems. That is, a method of manufacturing a vibration-type semiconductor sensor according to the present invention includes a bonding substrate body in which a first semiconductor substrate and a second semiconductor substrate are bonded and integrated with an etching stop layer interposed therebetween, and a base having a concave portion formed on the surface. First, anisotropic etching is performed from the surface side of the first semiconductor substrate of the bonding substrate body to partition the fixed electrode portion and the movable electrode portion, and the partition region is connected to the movable electrode portion. The region that models the supporting portion to be etched is removed until the etching stop layer is reached, and the fixed electrode portion, the movable electrode portion, and the supporting portion are processed and formed. Thereafter, the movable electrode portion of the bonded substrate body is formed in the concave portion of the base. The fixed electrode portion and the support portion are joined and fixed to the base by aligning, and then etching is performed from the front surface side of the second semiconductor substrate, so that the thickness of the second semiconductor substrate becomes a predetermined thickness. Was When the etching of the second semiconductor substrate is completed, a passage from the surface of the second semiconductor substrate to the etching stop layer is formed in the second semiconductor substrate, and the etching is performed on the etching stop layer through the passage. The second semiconductor substrate is peeled off by etching the etching stop layer by eroding the liquid,
The above-mentioned problem is solved by a configuration in which the fixed electrode portion and the movable electrode portion are separated from each other. In the invention having the above structure, after the supporting portion of the bonded substrate and the fixed electrode portion are bonded to the base, the second semiconductor substrate is left by a predetermined thickness.
The stress of the etching stop layer generated at the bonding interface with the first semiconductor substrate is offset by the stress of the etching stop layer generated at the bonding interface with the second semiconductor substrate, and the etching stop caused by the stress of the bonding interface is performed. Layer warpage is avoided. As described above, since the warpage of the etching stop layer is avoided, the problem that the support portion and the fixed electrode portion are lifted by the warpage of the etching stop layer and the support portion and the fixed electrode portion are separated from the base can be prevented. Thus, the yield of the vibration-type semiconductor sensor can be improved, and an inexpensive vibration-type semiconductor sensor can be provided. Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a method of manufacturing a vibration type semiconductor sensor according to this embodiment. The vibration type semiconductor sensor shown in this embodiment has the same configuration as that of the prior art shown in FIG. 2, and FIG. 1 shows an example of the manufacturing process of the vibration type semiconductor sensor shown in FIG. It is indicated by the section of the part. Since the configuration of the vibration-type semiconductor sensor of FIG. 2 has been described above, a duplicate description thereof will be omitted. In this embodiment, a first semiconductor substrate 12 formed of a silicon substrate and a second semiconductor substrate 13 formed of a silicon substrate are joined together in advance by sandwiching an etching stop layer 14 formed of silicon oxide. An SOI (Silicon on insulator) substrate is used as the bonding substrate body 15, and the support portion 2, the movable electrode portion 20 (the movable portion 3 and the movable electrode 4), and the fixed electrode portion are provided on the first semiconductor substrate 12 as described above. 21 (fixed portion 7 and fixed electrode 8) and beam portion 22 are processed and formed by using a photo-etching method. On the other hand, concave portion 5 is formed in base 1 formed of a glass substrate, and the bottom surface of concave portion 5 is formed. Forming the detection electrode 6 and forming the lead conductor 10 and the electrode pad 11, the movable electrode portion 20 of the bonding substrate 15 is aligned with the concave portion 5 of the base 1 as shown in FIG. On the base 1 The case substrate 15 is disposed, is joined by anodic bonding to the support portion 2 which is a contact portion between the base 1 and the fixing portion 7 of the fixed electrode portion 21 to the base 1. The thickness of the first semiconductor substrate 12 of the SOI substrate is formed to be much thinner than that of the second semiconductor substrate 13. Next, as shown in FIG. 1B, etching is performed from the surface side of the second semiconductor substrate 13 by an etching technique such as plasma etching or wet etching to reduce the thickness of the second semiconductor substrate 13. The thickness is reduced to a predetermined thickness (for example, substantially the same thickness as the thickness of the first semiconductor substrate 12). Thereafter, a passage 18 reaching the etching stop layer 14 from the surface of the second semiconductor substrate 13 is formed in the second
Then, an etching solution (for example, a fluorine oxide aqueous solution) is eroded from the passage 18 into the etching stop layer 14 to remove the etching stop layer 14 by etching. Since the silicon substrate is not etched by this etchant, the etchant does not damage the support 2, movable electrode 20, fixed electrode 21, and beam 22. As the etching stop layer 14 is removed by etching, the second semiconductor substrate 13 is peeled off.
(D), the movable electrode part 20 and the fixed electrode part 2
1 is separated to complete the vibration type semiconductor sensor. According to this embodiment, after bonding the bonding substrate body 15 to the base 1, the second semiconductor substrate 13 is not removed by a predetermined thickness instead of removing the entire second semiconductor substrate 13. , The stress of the etching stop layer 14 generated at the bonding interface with the first semiconductor substrate 12 is:
The warpage of the etching stop layer 14 caused by the stress at the bonding interface, which is offset by the stress of the etching stop layer 14 generated at the bonding interface with the second semiconductor substrate 13, can be prevented. As described above, since the warpage of the etching stop layer 14 can be prevented, the problem caused by the warpage of the etching stop layer 14 described above, that is, the support portion 2 and the fixed portion 7 can be lifted, and the problem that the support portion 2 and the fixing portion 7 are peeled off from the base 1 can be avoided, and it is easy to improve the yield of the vibration type semiconductor sensor. Can be made cheaper. The present invention is not limited to the above-described embodiment, but can adopt various embodiments. For example, in the above embodiment, the first semiconductor substrate 12 and the second
Although the SOI substrate is used in which the semiconductor substrate 13 is pre-joined and integrated with the etching stop layer 14 interposed therebetween, the first semiconductor substrate 12 and the second semiconductor substrate 13 are separately prepared, and the first semiconductor substrate 13 is used. 12 and second semiconductor substrate 1
3 may be joined and integrated via an etching stop layer 14 to produce a joined substrate body 15. In the above embodiment, the etching stop layer 14 is formed of silicon oxide.
It may be formed of a glass material. Furthermore, in the above embodiment, the base 1 is formed of a glass substrate, but may be formed of an insulator other than glass. Further, in the above embodiment, the first semiconductor substrate 12 and the second
Although the semiconductor substrate 13 is composed of a silicon substrate, it may be composed of a semiconductor substrate of germanium other than silicon. Further, in the above embodiment, when performing anisotropic etching of the first semiconductor substrate 12, a KOH aqueous solution is used as an etchant. However, the first semiconductor substrate 12 can be anisotropically etched. If the solution does not erode the etching stop layer 14, the above K
An etchant other than the OH aqueous solution may be used. Further, the etching of the first semiconductor substrate 12 is performed by low-temperature RIE.
It can also be performed by dry etching such as. Further, in this embodiment, the vibration type semiconductor sensor shown in FIG. 2 has been described as an example, but the method of manufacturing the vibration type semiconductor sensor of the present invention is not limited to the vibration type semiconductor sensor shown in FIG. The present invention can also be applied to a semiconductor sensor (a micro gyro, an acceleration sensor, or the like having a different configuration). According to the present invention, the second semiconductor substrate is left by a predetermined thickness after the bonding substrate is bonded to the base, so that the bonding interface with the first semiconductor substrate is formed. The generated stress of the etching stop layer is offset by the stress of the etching stop layer generated at the bonding interface with the second semiconductor substrate, and the warpage of the etching stop layer due to the stress at the bonding interface can be prevented. As described above, since the warpage of the etching stop layer can be prevented, the problem that the support portion and the fixed electrode portion are lifted due to the warpage of the etching stop layer and the support portion and the fixed electrode portion are peeled off from the base. Can be avoided. Thus, the yield of the vibration type semiconductor sensor can be improved.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an explanatory view showing one embodiment of a method for manufacturing a vibration type semiconductor sensor according to the present invention. FIG. 2 is an explanatory diagram showing an example of a vibration type semiconductor sensor. FIG. 3 is an explanatory view showing an example of a conventional method of manufacturing a vibration type semiconductor sensor. FIG. 4 is an explanatory view showing an example of a manufacturing process of the base. DESCRIPTION OF REFERENCE NUMERALS 1 base 2 support part 3 movable part 4 movable electrode 5 concave part 7 fixed part 8 fixed electrode 12 first semiconductor substrate 13 second semiconductor substrate 14 etching stop layer 15 bonding substrate body 16 partition area 17 area 18 passage 20 movable electrode section 21 fixed electrode section

Claims (1)

(57) [Claim 1] A bonded substrate body in which a first semiconductor substrate and a second semiconductor substrate are bonded and integrated with an etching stop layer interposed therebetween, and a base having a concave portion formed on the surface. First, anisotropic etching is performed from the surface side of the first semiconductor substrate of the bonding substrate body to partition the fixed electrode portion and the movable electrode portion, and the partition region is connected to the movable electrode portion. The region that models the supporting portion to be etched is removed until the etching stop layer is reached, and the fixed electrode portion, the movable electrode portion, and the supporting portion are processed and formed. Thereafter, the movable electrode portion of the bonded substrate body is formed in the concave portion of the base. The fixed electrode portion and the support portion are joined and fixed to the base by aligning, and then etching is performed from the front surface side of the second semiconductor substrate, so that the thickness of the second semiconductor substrate becomes a predetermined thickness. When the second semiconductor After the etching of the plate is completed, a passage from the surface of the second semiconductor substrate to the etching stop layer is formed in the second semiconductor substrate, and the etching solution is eroded into the etching stop layer through the passage to stop the etching. A method for manufacturing a vibration-type semiconductor sensor in which a layer is removed by etching to peel off a second semiconductor substrate and separate a fixed electrode portion and a movable electrode portion.