Condenser microphone, semiconductor structure and testing method thereof

Abstract

The invention discloses a condenser microphone, a semiconductor structure and a testing method thereof. The semiconductor structure comprises a supporting layer, a capacitor structure and a plurality of bonding pads. The capacitor structure comprises a back plate and a vibrating diaphragm which are oppositely arranged. And the plurality of bonding pads are located on the surface, far away from the substrate, of the supporting layer and are electrically connected with the vibrating diaphragm through the conductive structures. The conductive structure comprises a conductive hole located in the capacitor structure, and after the conductive hole penetrates through the backboard, the bottom of the conductive hole is in direct contact with the vibrating diaphragm. Therefore, when the semiconductor structure is used for performing defect detection on the conductive holes, a plurality of probes can be applied by a plurality of bonding pads, so that the problem that the probes directly applied to the conductive holes due to a single bonding pad cannot find positions due to small sizes and inconsistent depths (caused by multiple times of etching) of the conductive holes is avoided, and the defect detection accuracy is improved. The problems that detection cannot be carried out and detection data is unstable are further caused.

Description

Technical Field

[0001] This invention relates to the field of semiconductor technology, and in particular to a condenser microphone, a semiconductor structure, and a testing method thereof. Background Technology

[0002] Condenser microphones (MEMS microphones) primarily utilize the principle of capacitance, consisting of a diaphragm and a backplate. A gap of a few micrometers exists between the diaphragm and the backplate, forming a capacitor structure. The highly sensitive diaphragm senses external audio pressure signals and then changes the distance between the diaphragm and the backplate.

[0003] Currently, both the diaphragm and backplane can be connected to pads (PADs) via wires. However, for PADs electrically connected to the diaphragm, because there are many other layers above the diaphragm, these other layers need to be etched away before metal can be deposited in the contact holes / conductive vias and then connected to the pads. Due to the deposition characteristics of metal, the metal is relatively thin on the sidewalls, leading to some losses in subsequent manufacturing processes. In some areas near the edges, metal sidewall fractures may occur, resulting in the metal in the conductive vias not being connected to the diaphragm, causing product failure. Summary of the Invention

[0004] One objective of this invention is to provide a condenser microphone, a semiconductor structure, and a testing method thereof. By setting multiple pads on a support layer, and having each pad connected to a conductive structure that leads out the diaphragm, multiple probes can be set on the multiple pads and voltage can be applied, thereby ultimately improving the detection efficiency and accuracy of the condenser microphone.

[0005] To achieve the above objectives, one embodiment of the present invention provides a semiconductor structure, comprising:

[0006] The base has a dorsal cavity;

[0007] A support layer is located on the substrate, and has a receiving cavity in the central region;

[0008] A capacitor structure is located within the accommodating cavity and communicates with the back cavity of the substrate through the support layer. The capacitor structure includes a back plate and a diaphragm disposed opposite to each other, and the diaphragm is disposed on the side closer to the surface of the substrate.

[0009] Multiple pads are located on the surface of the support layer away from the substrate and are electrically connected to the diaphragm through conductive structures.

[0010] Optionally, the conductive structure may include:

[0011] A conductive hole is located within the capacitor structure and extends through the back plate so that its bottom is in direct contact with the diaphragm.

[0012] Optionally, the conductive hole may be filled with a metallic material.

[0013] Optionally, the top surface of the conductive hole may be flush with the top surface of the back plate.

[0014] Optionally, the shape and / or size of the plurality of pads may be the same or different.

[0015] Optionally, the pads include a first pad and a second pad, which are disposed on the support layer on both sides of the conductive hole with the conductive hole as the center.

[0016] Optionally, the projection of the pad in the direction perpendicular to the substrate at least partially overlaps with the projection of the conductive via in the direction perpendicular to the substrate.

[0017] To achieve the above objectives, one embodiment of the present invention also provides a condenser microphone, which may include the semiconductor structure described above.

[0018] To achieve the above objectives, one embodiment of the present invention also provides a method for testing semiconductor structures, comprising:

[0019] A semiconductor structure as described above is provided, wherein the semiconductor structure includes a first pad and a second pad, the first pad and the second pad being symmetrically disposed on the support layer on both sides of the conductive hole with the conductive hole as the center;

[0020] The semiconductor structure is placed on the carrier plate of the probe station, and the two probes of the probe card are respectively in contact with the first pad and the second pad;

[0021] A voltage is applied to the first pad and the second pad using the probe, and the current between the first pad and the second pad is detected.

[0022] Calculate the resistance value based on the voltage and current.

[0023] Optionally, the test method may further include:

[0024] The calculated resistance value is compared with the resistance value in the preset resistance library, and the abnormal information of the conductive hole corresponding to the calculated resistance value is determined from the preset resistance library; wherein, the abnormal information of the conductive hole includes abnormal information of metal fracture inside the hole.

[0025] As described above, the semiconductor structure of the present invention includes a support layer, a capacitor structure, and multiple pads. The support layer is located on a substrate and has a central cavity. The capacitor structure is located within the cavity and communicates with the back cavity of the substrate through the support layer. The capacitor structure includes a backplate and a diaphragm disposed opposite to each other, with the diaphragm positioned on a side closer to the substrate surface. The multiple pads are located on the surface of the support layer away from the substrate and are electrically connected to the diaphragm via conductive structures. Because the present invention includes multiple pads, and each pad is connected to a conductive hole of the electrically led-out diaphragm, when using this semiconductor structure to perform defect detection on conductive holes, multiple probes can be applied using multiple pads. This avoids the problem of probes being directly applied to conductive holes due to the small size and inconsistent depth of the conductive holes (caused by multiple etching processes), leading to undetectable defects and unstable detection data. Attached Figure Description

[0026] The accompanying drawings provide a more detailed understanding of embodiments of the invention and are incorporated herein by reference as a whole. These drawings and descriptions are used to illustrate the principles of some embodiments. It should be noted that all drawings are schematic diagrams, and for illustrative and drafting purposes, relative sizes and proportions have been adjusted. The same symbols represent corresponding or similar features in different embodiments.

[0027] Figure 1 The illustration shows a top view of a semiconductor structure, specifically a capacitor microphone, in one embodiment of the present invention.

[0028] Figure 2 The drawing is shown as Figure 1 A partial cross-sectional view of the semiconductor structure along the AA tangent.

[0029] The reference numerals in the attached figures are explained as follows:

[0030] 100-Substrate, 110-Support layer, 120-Capacitor structure, 130-Pad, 101-Back cavity, 102-Accommodation cavity, 121-First sacrificial layer, 122-Diaphragm, 123-Second sacrificial layer, 124-Backplate, 131-First pad, 132-Second pad, 141-Conductive via. Detailed Implementation

[0031] To enable those skilled in the art to further understand the present invention, preferred embodiments are described below in conjunction with the accompanying drawings to explain in detail the composition and desired effects of the invention. It should be understood that the features described below can be substituted, rearranged, or mixed to achieve other embodiments without departing from the spirit of the invention.

[0032] The invention is described more specifically by way of example in the following paragraphs with reference to the accompanying drawings. The advantages and features of the invention will become clearer from the following description and claims. It should be noted that the drawings are in a very simplified form and use non-precise proportions, intended only to facilitate and clarify the illustration of the embodiments of the invention. It is understood that the terms "on," "above," and "over" in this invention should be interpreted in the broadest sense, such that "on" means not only "on" something without any intervening feature or layer (i.e., directly on something), but also includes "on" something with an intervening feature or layer.

[0033] Furthermore, for ease of description, regional relative terms such as “on,” “above,” “above,” “upper,” “above,” “upper,” etc., may be used herein to describe the relationship between one element or feature and another element or feature as shown in the figures. In addition to the orientations depicted in the figures, regional relative terms are intended to cover different orientations of the device in use or operation. The device may be oriented in other ways (rotated 90 degrees or in other orientations) and the regional relative descriptive terms used herein may be interpreted accordingly.

[0034] In the embodiments of the present invention, the terms "first," "second," etc., are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be noted that the technical solutions described in the embodiments of the present invention can be arbitrarily combined without conflict.

[0035] Currently, both the diaphragm and backplane can be connected to pads (PADs) via wires. However, for PADs electrically connected to the diaphragm, because there are many other layers above the diaphragm, these other layers need to be etched away before metal can be deposited in the contact holes / conductive vias and then connected to the pads. Due to the deposition characteristics of metal, the metal is relatively thin on the sidewalls, leading to some losses in subsequent manufacturing processes. Some areas near the edges may experience metal sidewall fractures, resulting in the metal in the conductive vias not connecting to the diaphragm, causing product failure. Current online microscopy and defect scanning methods cannot effectively monitor this problem, and existing electrical tests are also ineffective. If a two-end test method is used, with one end connected to the contact hole and the other to the diaphragm PAD, the resistance can be calculated by monitoring the current at both ends. Monitoring the resistance shows that when the metal is not broken, the resistance is very small; when it is broken in half, the resistance can be considered to have decreased by half; but when the metal is completely broken, the resistance suddenly becomes very large.

[0036] Therefore, in the existing technology, it is impossible to use microscopes and defect scanning to monitor whether the metal material on the sidewalls of the contact holes or conductive holes used for electrical lead-out diaphragms in condenser microphones has broken. Secondly, even if a pin card is designed to monitor the resistance of the metal in the contact holes or conductive holes of the diaphragm using a two-end test method, the small size of the contact holes or conductive holes and the many etching processes involved result in differences between each chip / wafer and production batch. This leads to excessively large differences in the depth of the contact holes or conductive holes on different chips / wafers, resulting in the inability to conduct unified testing, i.e., problems of low testing efficiency and unstable test data.

[0037] To address the aforementioned issues, this invention provides a condenser microphone, a semiconductor structure, and a testing method thereof. Specifically, at least two pads are provided for the conductive hole that electrically connects to the diaphragm. Multiple probes can then be applied through these pads. By adding pads, different areas of the conductive hole can be effectively electrically led out, thereby enabling the testing of the conductive hole and improving testing efficiency and accuracy, thus achieving the objective of this invention.

[0038] The semiconductor structure and its testing method proposed in the embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0039] For ease of understanding, the following text defines directions parallel to the substrate 100 and directions perpendicular to the surface of the substrate 100. For simplicity, the direction parallel to the surface of the substrate 100 will be referred to as the horizontal direction, and the direction perpendicular to the surface of the substrate 100 will be referred to as the vertical direction.

[0040] Please refer to Figure 1 and Figure 2 ,in, Figure 1 The illustration is a top view of a semiconductor structure for a capacitor microphone in one embodiment of the present invention. Figure 2 The illustration is Figure 1 A partial cross-sectional view of the semiconductor structure along the AA tangent.

[0041] like Figure 1 and Figure 2As shown, the semiconductor structure includes: a substrate 100, a support layer 110, a capacitor structure 120, and multiple pads 130. The substrate 100 can be made of any suitable substrate material well known to those skilled in the art, such as at least one of the following: silicon, silicon-on-insulator (SOI), silicon-on-insulator stacked (SSOI), silicon-on-insulator stacked (S-SiGeOI), silicon-on-insulator (SiGeOI), and germanium-on-insulator (GeOI). This application does not limit the material of the substrate 100. Furthermore, the substrate 100 has a front side and a back side disposed opposite to each other. The support layer 110, capacitor structure 120, and multiple pads 130 are disposed on the front side of the substrate 100, while a back cavity 101 is disposed on the back side of the substrate 100. The support layer 110 is located on the front side of the substrate 100, and an accommodating cavity 102 is disposed within it, for example, in the central region. The accommodating cavity 102 is used to house the capacitor structure 120. Figure 1 As shown, from a top view, the shape of the accommodating cavity 102 can be circular, and the top view structure of the capacitor structure 120 is the same as the shape of the accommodating cavity 102, so that the sidewall of the accommodating cavity 102 and the sidewall of the capacitor structure 120 fit and contact each other, but this is not a limitation.

[0042] The material of the support layer 110 can be a single layer or multiple layers of insulating material, such as silicon oxide (SiO2), silicon nitride (SiN), silicon oxynitride (SiON), silicon carbide nitride (SiCN), or a combination of the above materials, but is not limited thereto. For example, in this embodiment of the invention, the support layer 110 is a single layer of insulating material, and the projection of the accommodating cavity 102 in the vertical direction at least partially overlaps with the projection of the back cavity 101 in the vertical direction within the substrate 100, so that some components inside the capacitor structure 120 housed in the accommodating cavity 102, such as release holes, vent holes, cavities, etc., can communicate with the back cavity 101 within the substrate 100, thereby achieving the function of a capacitor microphone.

[0043] The capacitor structure 120 is housed within the accommodating cavity 102 and includes a diaphragm 122 and a backplate 124 disposed opposite to each other, with the diaphragm 122 disposed on the side closest to the surface of the substrate 100 (i.e., the front side of the substrate 100). Specifically, the capacitor structure 120 may be a semiconductor device such as a condenser microphone, and may include conventional components and / or devices of a condenser microphone such as a diaphragm, backplate, sacrificial layer, isolation layer, etc. In this embodiment, the capacitor structure 120 may specifically include a first sacrificial layer 121, a diaphragm 122, a second sacrificial layer 123, and a backplate 124 stacked sequentially from bottom to top. The first sacrificial layer 121 is located on the surface of the substrate 100 exposed at the bottom of the accommodating cavity 102, and also has an opening in the central region, which communicates with the backplate 101. The diaphragm 122 is located within the opening, and its two ends in the horizontal direction are respectively inserted into the first sacrificial layer 121, such that most of the area of ​​the diaphragm 122 is suspended in the opening. The diaphragm 122 may also have a plurality of spaced-apart through holes (not labeled) in its central region. These through holes communicate with the back cavity 101 to serve as the vibrating part of the diaphragm 122. The second sacrificial layer 123 is located above the diaphragm 122 and has a cavity (not labeled) in the central region facing the diaphragm 122. The back plate 124 is located in front of the second sacrificial layer 123 and has a plurality of acoustic holes (not labeled) stacked above the cavity in the second sacrificial layer 123 and the back plate 124. The acoustic holes, the cavity, and the back cavity 101 are connected. In one embodiment, the diaphragm 122 may be a composite structure, such as a sandwich structure consisting of a first nitride layer (material for example, silicon nitride), a second polycrystalline silicon layer (material for example, polycrystalline silicon), and a third nitride layer (material for example, silicon nitride) stacked sequentially from bottom to top. The materials of the first sacrificial layer 121 and the second sacrificial layer 123 may be insulating materials such as silicon oxide or silicon nitride, but are not limited thereto.

[0044] The plurality of pads 130 are located on the surface of the support layer 110 on one side of the capacitor structure 120, away from the substrate 100, and are electrically connected to the diaphragm 122 through a conductive structure 140. The conductive structure 140 includes a conductive hole 141. In one embodiment, the conductive hole 141 is located within the capacitor structure 120, for example, in the material of the back plate 124, the second sacrificial layer 123, and the first sacrificial layer 121 on one side of the cavity, and penetrates the back plate 124, the second sacrificial layer 123, and part of the first sacrificial layer 121, so that the bottom of the conductive hole 141 is in direct contact with the diaphragm 122, serving as a contact hole for electrically leading out the diaphragm 122; the conductive hole 141 is filled with a metallic material, and its top surface is flush with the top surface of the back plate 124. Since the conductive hole 141 is filled with metal material, and the size of the conductive hole 141 is usually small, during the process of forming the contact hole area and metal material of the conductive hole 141 in the back plate 124, the second sacrificial layer 123 and part of the first sacrificial layer 121 using etching, deposition and other processes, it is very easy for the metal deposited on the sidewall of the corresponding contact hole of the conductive hole 141 to break. The existing technology only sets a pad at one end of the conductive hole. Therefore, when using a probe to detect whether the metal in the contact hole (the corresponding position of the conductive hole) has broken or other defects, it is impossible to detect because it only has a pad. Or, it is also impossible to accurately detect the problem by directly contacting the probe with the metal in the contact hole.

[0045] like Figure 1 As shown, in this embodiment of the invention, a pad is provided on each side of the planar area corresponding to the conductive hole 141, such as a first pad 131 and a second pad 132. The shape and size of the first pad 131 and the second pad 132 are preferably the same, but they can be different, though not limited thereto. In one embodiment, the first pad 131 and the second pad 132 are symmetrically arranged on the support layer 110 on both sides of the conductive hole 141, with the conductive hole 141 as the center, but not limited thereto. Furthermore, the projections of the first pad 131 and the second pad 132 in the direction perpendicular to the substrate 100 must overlap with the projection of the conductive hole 141 in the direction perpendicular to the substrate 100, so that both the first pad 131 and the second pad 132 can be electrically connected to the conductive hole 141. Thus, when applying voltage and detecting current to the pad 130 using a probe to calculate the resistance of the metal material in the conductive hole 141 to determine whether the metal material has defects such as breakage, the accuracy of the judgment result can be improved by taking into account the different resistance characteristics of different metal materials and avoiding the influence of defects in the metal material in the conductive hole 141 on the accuracy of the judgment result.

[0046] Furthermore, based on Figures 1 to 2The semiconductor structure shown in the invention may also be provided in other embodiments as a capacitor microphone, which may include at least the semiconductor structure described above. Since the semiconductor structure provided in the embodiments of the invention has multiple pads, and each pad is connected to a conductive hole of the electrically led-out diaphragm, when using a capacitor microphone protecting multiple pads to perform defect detection on the conductive holes of its electrically led-out diaphragm, multiple probes can be applied using multiple pads. This avoids the problem of probes directly applied to the conductive holes being unable to be detected due to their small size and unstable detection data, thus improving the detection efficiency and accuracy of the capacitor microphone.

[0047] Furthermore, in order to enable those skilled in the art to easily understand how the semiconductor structure in the embodiments of the present invention is tested, other embodiments of the present invention also provide a test method for testing the semiconductor structure and a capacitive microphone including the semiconductor structure, as detailed below.

[0048] Specifically, the test method for testing the semiconductor structure and the capacitive microphone containing the semiconductor structure in the embodiments of the present invention may include at least the following steps:

[0049] Step S101, provide as follows Figures 1 to 2 The semiconductor structure includes a first pad 131 and a second pad 132, wherein the first pad 131 and the second pad 132 are disposed on the support layer 110 on both sides of the conductive hole 141 with the conductive hole 141 as the center.

[0050] Step S102: Place the semiconductor structure on the carrier plate of the probe station, and make the two probes of the probe card contact the first pad 131 and the second pad 132 respectively.

[0051] Step S103: Apply a voltage to the first pad 131 and the second pad 132 through the probe, and detect the current between the first pad 131 and the second pad 132.

[0052] Step S104: Calculate the resistance value based on the voltage and current;

[0053] Step S105: Compare the calculated resistance value with the resistance value in the preset resistance library, and determine the conductive hole abnormal information corresponding to the calculated resistance value from the preset resistance library; wherein, the conductive hole abnormal information includes abnormal information of metal fracture inside the hole.

[0054] In this embodiment, voltage can be applied to the metal material in the conductive hole 141 through the first pad 131 and the second pad 132 to form a circuit. By detecting the current in the circuit, the resistance value of the metal in the conductive hole 141 can be calculated using the resistance calculation formula. If the metal on the sidewall is broken, the calculated resistance value is extremely large. If no breakage occurs, the calculated resistance value is relatively small. Thus, the purpose of automatically identifying multiple failed chips on the wafer can be achieved, and the failed chips can be subjected to subsequent INK processing, that is, marking the surface of the selected failed chips so that they can be removed in subsequent processes.

[0055] In summary, the semiconductor structure of the present invention includes a support layer, a capacitor structure, and multiple pads. The support layer is located on a substrate and has a central cavity. The capacitor structure is located within the cavity and communicates with the back cavity of the substrate through the support layer. The capacitor structure includes a backplate and a diaphragm disposed opposite to each other, with the diaphragm positioned on the side closest to the substrate surface. The multiple pads are located on the surface of the support layer away from the substrate and are electrically connected to the diaphragm via conductive structures. Because the present invention includes multiple pads, each connected to a conductive hole of the electrically led-out diaphragm, when using this semiconductor structure to detect defects in conductive holes, multiple probes can be applied using multiple pads. This avoids the problem of probes being directly applied to conductive holes due to the small size and inconsistent depth of the conductive holes (caused by multiple etching processes), leading to undetectable defects and unstable detection data.

[0056] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A semiconductor structure, characterized in that, include: The base has a dorsal cavity; A support layer is located on the substrate, and has a receiving cavity in the central region; A capacitor structure is located within the accommodating cavity and communicates with the back cavity of the substrate through the support layer. The capacitor structure includes a back plate and a diaphragm disposed opposite to each other, and the diaphragm is disposed on the side closer to the surface of the substrate. Multiple pads are located on the surface of the support layer away from the substrate and are electrically connected to the diaphragm through conductive structures.

2. The semiconductor structure as described in claim 1, characterized in that, The conductive structure includes: A conductive hole is located within the capacitor structure and extends through the back plate so that its bottom is in direct contact with the diaphragm.

3. The semiconductor structure as described in claim 2, characterized in that, The conductive hole is filled with metallic material.

4. The semiconductor structure as described in claim 2, characterized in that, The top surface of the conductive hole is flush with the top surface of the back plate.

5. The semiconductor structure as described in claim 1, characterized in that, The multiple pads may have the same or different shapes and / or sizes.

6. The semiconductor structure as described in claim 2, characterized in that, The pads include a first pad and a second pad, which are symmetrically arranged on the support layer on both sides of the conductive hole with the conductive hole as the center.

7. The semiconductor structure as described in claim 6, characterized in that, The projection of the pad in the direction perpendicular to the substrate at least partially overlaps with the projection of the conductive via in the direction perpendicular to the substrate.

8. A condenser microphone, characterized in that, Includes the semiconductor structure as described in any one of claims 1 to 7.

9. A method for testing semiconductor structures, characterized in that, include: A semiconductor structure as described in any one of claims 1 to 7 is provided, wherein the semiconductor structure includes a first pad and a second pad, the first pad and the second pad being disposed on the support layer on both sides of the conductive hole with the conductive hole as the center; The semiconductor structure is placed on the carrier plate of the probe station, and the two probes of the probe card are respectively in contact with the first pad and the second pad; A voltage is applied to the first pad and the second pad using the probe, and the current between the first pad and the second pad is detected. Calculate the resistance value based on the voltage and current.

10. The test method as described in claim 9, characterized in that, Also includes: The calculated resistance value is compared with the resistance value in the preset resistance library, and the abnormal information of the conductive hole corresponding to the calculated resistance value is determined from the preset resistance library; wherein, the abnormal information of the conductive hole includes abnormal information of metal fracture inside the hole.

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