CN111740006A - Semiconductor device and method of forming the same - Google Patents

Semiconductor device and method of forming the same Download PDF

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CN111740006A
CN111740006A CN202010244999.XA CN202010244999A CN111740006A CN 111740006 A CN111740006 A CN 111740006A CN 202010244999 A CN202010244999 A CN 202010244999A CN 111740006 A CN111740006 A CN 111740006A
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layer
upper electrode
electrode layer
passivation
forming
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CN111740006B (en
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项少华
王冲
王大甲
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Smic Yuezhou Integrated Circuit Manufacturing Shaoxing Co ltd
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SMIC Manufacturing Shaoxing Co Ltd
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    • HELECTRICITY
    • H10SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10NELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N30/00Piezoelectric or electrostrictive devices
    • H10N30/01Manufacture or treatment
    • H10N30/06Forming electrodes or interconnections, e.g. leads or terminals
    • GPHYSICS
    • G03PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03FPHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
    • G03F7/00Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
    • G03F7/26Processing photosensitive materials; Apparatus therefor
    • G03F7/42Stripping or agents therefor
    • HELECTRICITY
    • H10SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10NELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N30/00Piezoelectric or electrostrictive devices
    • H10N30/01Manufacture or treatment
    • H10N30/02Forming enclosures or casings
    • HELECTRICITY
    • H10SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10NELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N30/00Piezoelectric or electrostrictive devices
    • H10N30/80Constructional details
    • H10N30/87Electrodes or interconnections, e.g. leads or terminals
    • HELECTRICITY
    • H10SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10NELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N30/00Piezoelectric or electrostrictive devices
    • H10N30/80Constructional details
    • H10N30/88Mounts; Supports; Enclosures; Casings

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  • Manufacturing & Machinery (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Piezo-Electric Or Mechanical Vibrators, Or Delay Or Filter Circuits (AREA)
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Abstract

The invention provides a semiconductor device and a forming method thereof. Before the stripping process is executed, the passivation layer is not provided with a suspended part, so that the problem that the suspended part of the passivation layer is damaged can not occur when the stripping process is executed, the performance of a formed semiconductor device is guaranteed, the spraying pressure of stripping liquid can be further increased when the photoresist layer is removed, the stripping efficiency of the photoresist layer is improved, and the problem that the photoresist layer cannot be completely removed is solved.

Description

Semiconductor device and method of forming the same
Technical Field
The present invention relates to the field of semiconductor technology, and more particularly, to a semiconductor device and a method for forming the same.
Background
Semiconductor devices, which are made using the inverse piezoelectric effect of piezoelectric materials, are key elements of crystal oscillators and filters, which are often applied to bulk acoustic wave filters. Fig. 1a to 1b are schematic structural views of a semiconductor device in a manufacturing process thereof, and a method for forming the semiconductor device, as shown in fig. 1a to 1b, may include the following steps.
Step one, specifically referring to fig. 1a, a substrate 10 is provided, and a lower electrode layer and a piezoelectric material layer 30 are sequentially formed on the substrate 10. And, an upper electrode material layer 40a and a patterned passivation layer 50 are further formed on the lower electrode layer and the piezoelectric material layer 30.
Step two, referring to fig. 1b specifically, the upper electrode material layer 40a is etched by using a wet etching process to form an upper electrode layer 40 a.
Specifically, when the upper electrode material layer 40a is etched, the etchant in the wet etching process further laterally erodes a portion of the upper electrode material layer 40a directly below the passivation layer 50, so that the end of the formed upper electrode layer 40 is retracted relative to the end of the passivation layer 50. At this time, the end of the passivation layer 50 is correspondingly extended relative to the upper electrode layer 40 to at least partially form a suspended portion, which is suspended above the piezoelectric material layer 30.
And step three, forming a contact pad by utilizing a stripping process so as to lead out the upper electrode layer or the lower electrode layer electrically.
Specifically, the stripping process comprises the following steps: firstly, forming a photoresist layer on the substrate 10, wherein the photoresist layer correspondingly covers the passivation layer 50, and an opening is formed in the photoresist layer to expose an area where a contact pad needs to be formed; then, forming a conductive material layer which covers the photoresist layer and is also formed in a region corresponding to the opening; then, the photoresist layer is stripped to remove the part of the conductive material layer covering the photoresist layer, and the part of the conductive material layer corresponding to the opening is reserved to form a contact pad.
It should be noted that, in the process of stripping the photoresist layer, the stripping solution is usually sprayed on the photoresist layer with a large spraying pressure. However, a high spraying pressure may also act on the passivation layer 50, and the suspended portion of the passivation layer 50 may be easily damaged by the high-pressure spraying. Based on this, in order to avoid the damage of the suspended portion of the passivation layer 50, the spraying pressure of the stripping liquid is usually reduced, however, this will directly cause the problem that the photoresist layer is not stripped cleanly. In addition, since the photoresist material of the photoresist layer is easily introduced into the space below the suspended portion of the passivation layer 50, the photoresist material introduced into the space below the suspended portion is also difficult to be removed.
Disclosure of Invention
The invention aims to provide a method for forming a semiconductor device, which solves the problem that a suspended part of a passivation layer is easy to damage in the conventional forming method.
In order to solve the above technical problem, the present invention provides a method for forming a semiconductor device, including:
providing a substrate, wherein a lower electrode layer and an extraction electrode are formed on the substrate, a piezoelectric material layer is further formed on the lower electrode layer and the extraction electrode, an upper electrode layer and a passivation layer are sequentially formed on the piezoelectric material layer, and a contact window is further formed in the piezoelectric material layer and exposes the extraction electrode;
performing a stripping process to form a contact pad on the extraction electrode, wherein the contact pad is electrically connected with the extraction electrode and is used for electrically extracting the upper electrode layer or the lower electrode layer; and the number of the first and second groups,
and laterally eroding at least one end part of the upper electrode layer so as to enable the at least one end part of the upper electrode layer to be retracted relative to the end part of the passivation layer, and forming a suspended part by utilizing the end part of the passivation layer extending relative to the upper electrode layer.
Optionally, the extraction electrode is used for electrically extracting the upper electrode layer; and the passivation layer exposes the connecting end of the upper electrode layer close to the extraction electrode, and the contact pad is electrically connected with the connecting end and the extraction electrode.
Optionally, the forming method of the upper electrode layer and the passivation layer includes: sequentially forming an upper electrode material layer and a passivation material layer on the piezoelectric material layer, etching the passivation material layer to form a passivation layer, and etching the upper electrode material layer by taking the passivation layer as a mask to form an upper electrode layer;
and, after etching the upper electrode material layer to form the upper electrode layer, further comprising:
and partially removing the end part of the passivation layer close to the extraction electrode so as to expose the connecting end of the upper electrode layer close to the extraction electrode.
Optionally, the forming method of the upper electrode layer and the passivation layer includes:
sequentially forming an upper electrode material layer and a passivation material layer on the piezoelectric material layer;
forming a first mask layer on the passivation material layer, and etching the passivation material layer by taking the first mask layer as a mask to form the passivation layer and expose part of the upper electrode material layer;
forming a second mask layer, wherein the second mask layer covers the passivation layer, and the end part of the second mask layer close to the extraction electrode also extends to cover part of the upper electrode material layer;
and etching the upper electrode material layer by taking the second mask layer as a mask to form the upper electrode layer, and removing the second mask layer to expose the connecting end of the upper electrode layer close to the extraction electrode.
Optionally, the method of performing a lift-off process to form the contact pad includes;
forming a light resistance layer, wherein an opening is also formed in the light resistance layer, and the contact window is exposed out of the opening of the light resistance layer;
forming a conductive material layer covering the photoresist layer, and the conductive material layer is further formed in a contact window exposed in the opening to be connected with the extraction electrode;
and stripping the photoresist layer to remove the part of the conductive material layer covering the photoresist layer and reserve the part of the conductive material layer corresponding to the opening to form the contact pad.
Optionally, the passivation layer exposes the connection end of the upper electrode layer close to the extraction electrode; wherein, when the photoresist layer is formed, the contact window and the connecting end of the upper electrode layer are exposed in the opening; and when the conductive material layer is formed, the conductive material layer also covers the connection end of the upper electrode layer so as to electrically connect the connection end and the contact pad.
Optionally, the method of laterally eroding the upper electrode layer includes: and laterally eroding the upper electrode layer by utilizing a wet etching process. Further, the etchant for the wet etching process comprises nitric acid.
Optionally, before performing the lift-off process, the at least one end portion of the upper electrode layer is recessed with respect to an end portion of the passivation layer, and the recessed value is less than or equal to 0.5 μm; or, the at least one end portion of the upper electrode layer extends out with respect to an end portion of the passivation layer, and an extension value of the extension is 0.5 μm or less.
Optionally, at least one end portion of the upper electrode layer is laterally eroded so that a retraction value of the at least one end portion of the upper electrode layer relative to an end portion of the passivation layer is greater than or equal to 0.7 μm.
Optionally, the material of the upper electrode layer includes molybdenum, and the material of the contact pad includes gold and/or copper.
Based on the above formation method, the present invention also provides a semiconductor device including:
a substrate;
an extraction electrode formed on the substrate;
a lower electrode layer formed on the substrate;
the piezoelectric material layer covers the lower electrode layer and the extraction electrode, a contact window is further formed in the piezoelectric material layer, and the bottom of the contact window extends to the extraction electrode;
an upper electrode layer formed on the piezoelectric material layer;
a passivation layer formed on the upper electrode layer and having a suspended portion extending from the upper electrode layer;
and the contact pad is at least formed in the contact window and is electrically connected with the extraction electrode so as to be used for electrically extracting the upper electrode layer or the lower electrode layer.
In the method for forming a semiconductor device provided by the invention, before the stripping process is performed, at least one end part (corresponding to the position of the suspended part to be formed later) of the formed upper electrode layer is flush or nearly flush with the end part of the passivation layer above the end part, namely, the passivation layer is not formed with the suspended part which is suspended and covered before the stripping process is performed. Therefore, when the subsequent stripping process is carried out, the problem that the suspended part is easy to damage does not exist, and the spraying pressure of the stripping liquid can be further increased when the photoresist layer is removed, so that the stripping efficiency of the photoresist layer is improved, and the problem that the photoresist layer cannot be completely removed is solved. In addition, because the passivation layer is not provided with the suspended part in the stripping process, a larger gap does not exist below the passivation layer correspondingly, so that the problem that the photoresist layer cannot be removed cleanly because the photoresist material in the stripping process is filled in the gap below the passivation layer can be avoided.
Drawings
FIGS. 1a to 1b are schematic structural views of a semiconductor device during a manufacturing process thereof;
fig. 2 is a schematic flow chart illustrating a method of forming a semiconductor device in accordance with an embodiment of the present invention;
fig. 3a to fig. 3f are schematic structural diagrams of a method for forming a semiconductor device in a manufacturing process of the semiconductor device according to an embodiment of the invention.
Wherein the reference numbers are as follows:
10/100-a substrate;
210-a lower electrode layer;
220-extraction electrode;
30/300-a layer of piezoelectric material;
310-a contact window;
40a/400 a-layer of top electrode material;
40/400 — upper electrode layer;
500 a-a layer of passivation material;
50/500-a passivation layer;
600-contact pad.
Detailed Description
As described in the background art, in the current method for manufacturing a semiconductor device, when the photoresist layer is removed based on a high-intensity spraying pressure, the suspended portion of the passivation layer is easily damaged. Therefore, even if the spraying pressure is reduced to avoid the damage of the suspended portion, the problem of incomplete photoresist layer removal is caused.
Therefore, the invention provides a method for forming a semiconductor device, which can prevent the problem that the suspended part in the passivation layer is damaged on the basis of completely removing the photoresist layer. For example, referring to fig. 2, the method for forming the semiconductor device includes:
step S100, providing a substrate, wherein a lower electrode layer and an extraction electrode are formed on the substrate, a piezoelectric material layer is further formed on the lower electrode layer and the extraction electrode, an upper electrode layer and a passivation layer are sequentially formed on the piezoelectric material layer, and a contact window is further formed in the piezoelectric material layer and exposes the extraction electrode;
step S200, performing a lift-off process to form a contact pad on the extraction electrode, where the contact pad is electrically connected to the extraction electrode and is used to electrically extract the upper electrode layer or the lower electrode layer;
step S300, laterally eroding at least one end portion of the upper electrode layer to make the at least one end portion of the upper electrode layer retract relative to an end portion of the passivation layer, and forming a suspended portion by using an end portion of the passivation layer extending relative to the upper electrode layer.
That is, in the forming method provided by the present invention, the contact pad is formed by a lift-off process, and then the upper electrode layer is laterally eroded, so that at least one end of the passivation layer forms a suspended portion. Compared with the traditional forming method in which the suspended part of the passivation layer is preferentially formed and then the stripping process is carried out, the forming method provided by the invention can ensure that the suspended part formed later is not influenced by the stripping process carried out earlier, and avoid the problem that the suspended part of the passivation layer is easily damaged under the action of high-pressure spraying in the traditional process.
The semiconductor device and the method for forming the same according to the present invention will be described in further detail with reference to the accompanying drawings and specific embodiments. The advantages and features of the present invention will become more apparent from the following description. It is to be noted that the drawings are in a very simplified form and are not to precise scale, which is merely for the purpose of facilitating and distinctly claiming the embodiments of the present invention.
Fig. 3a to fig. 3f are schematic structural diagrams of a method for forming a semiconductor device in a manufacturing process of the semiconductor device according to an embodiment of the invention.
In step S100, specifically referring to fig. 3a to 3d, a substrate 100 is provided, a lower electrode layer 210 and an extraction electrode 220 are sequentially formed on the substrate 100, a piezoelectric material layer 300 is further sequentially formed on the lower electrode layer 210 and the extraction electrode 220, a piezoelectric material layer 300 is further formed on the lower electrode layer 210 and the extraction electrode 220, an upper electrode layer 400 and a passivation layer 500 are sequentially formed on the piezoelectric material layer 300, and a contact window 310 is further formed in the piezoelectric material layer 300, wherein the contact window 310 exposes the extraction electrode 220.
Wherein the substrate 100 may be adjusted accordingly depending on the particular application of the semiconductor device being formed. For example, the semiconductor device may be a Bulk Acoustic Wave (BAW) filter, in which case the substrate may include multiple layers of bragg reflectors to further form a solid-state fabricated resonator (SMR); alternatively, the substrate may also include a cavity to further form a film bulk acoustic resonator Filter (FBAR).
Further, the lower electrode layer 210 and the upper electrode layer 400 may be formed using the same material. For example, the material of the lower electrode layer 210 and the upper electrode layer 400 may each include a metal material, and particularly, the metal material includes, for example, molybdenum (Mo). And, the material of the piezoelectric material layer 300 may include at least one of zinc oxide (ZnO), aluminum nitride (AlN), and lead zirconate titanate (PZT). In addition, in a specific embodiment, the passivation layer 500 may also be formed of the same material as the piezoelectric material layer 300, for example, each including aluminum nitride (AlN) or the like.
In this embodiment, the extraction electrode 220 is used to be electrically connected to the lower electrode layer 210 or to be electrically connected to the upper electrode layer 400, so that the lower electrode layer 210 or the upper electrode layer 400 can be electrically extracted through the extraction electrode 220. It can be understood that, when the lower electrode layer 210 realizes electrical extraction through the extraction electrode 220, a partial region of the lower electrode layer 210 may be considered to constitute the extraction electrode 220; alternatively, when the upper electrode layer 400 is electrically extracted through the extraction electrode 220, the upper electrode layer 400 and the extraction electrode 220 may be electrically connected through a conductive material in a subsequent process.
Alternatively, the extraction electrode 220 and the lower electrode layer 210 may be formed simultaneously, and the preparation method thereof includes: first, an electrode material layer is formed on the substrate 100; next, the electrode material layer is patterned to form the extraction electrode 220 and the lower electrode layer 210, respectively. When the extraction electrode 220 is used for electrically extracting the lower electrode layer 210, the extraction electrode 220 and the lower electrode layer 210 can be connected with each other; alternatively, when the extraction electrode 220 is used to electrically extract the upper electrode layer 400, the extraction electrode 220 and the lower electrode layer 210 may be separated from each other.
As described above, the piezoelectric material layer 300 covers the lower electrode layer 210 and the extraction electrode 220, and the upper electrode layer 400 and the passivation layer 500 are sequentially formed on the piezoelectric material layer 300.
The formation method of the upper electrode layer 400 and the passivation layer 500 includes, for example: referring first to fig. 3a, an upper electrode material layer 400a and a passivation material layer 500a are sequentially formed on the piezoelectric material layer 300; referring next to fig. 3b, the passivation material layer 500a is etched to form a passivation layer 500; then, as shown in fig. 3b, the passivation layer 500 is used as a mask to etch the upper electrode material layer 400a to form the upper electrode layer 400. Wherein the upper electrode material layer 400a may be etched using an anisotropic etching process. Further, the anisotropic etching process includes, for example, dry etching.
It should be noted that, based on the anisotropic etching process, the end of the upper electrode layer 400 can be formed to be flush or nearly flush with the end of the passivation layer 500 above the upper electrode layer. For example, when the end portion of the upper electrode layer 400 is recessed with respect to the end portion of the passivation layer 500, the recess value is 0.5 μm or less; alternatively, when the end portion of the upper electrode layer 400 extends out with respect to the end portion of the passivation layer 500, the extension value of the extension may be 0.5 μm or less. Further, it can be considered that when the end of the upper electrode layer 400 is leveled with respect to the end of the passivation layer 500, the recessing value is equal to 0 or the extending value is equal to 0.
It should be appreciated that, based on the current anisotropic etching process, the etching precision is high, and precise replication of the pattern can be achieved, so that the recession or extension value of the end portion of the upper electrode layer 400 formed by the anisotropic etching process relative to the end portion of the passivation layer 500 may be even further equal to or less than 0.3 μm.
Since the end of the upper electrode layer 400 is flush or nearly flush with the end of the passivation layer 500 above it, the upper electrode layer 400 can well support the passivation layer 500 above it. In other words, there is no floating covering portion in the passivation layer 500, so that the passivation layer 500 can bear a larger acting force, and the problem of damage due to the larger acting force in the subsequent process will not occur.
Further, projected images of the lower electrode layer 210 and the upper electrode layer 400 projected on the same horizontal plane at least partially overlap, and projected images of the upper electrode layer 400 and the extraction electrode 220 projected on the same horizontal plane at least partially do not overlap.
In this embodiment, the extraction electrode 220 is used for electrically extracting the upper electrode layer 400. Accordingly, the passivation layer 500 may also expose the connection end of the upper electrode layer 400 close to the extraction electrode 220, and the connection end and the extraction electrode 220 may be electrically connected by a contact pad formed later.
In a specific embodiment, referring to fig. 3c, an end portion of the passivation layer 500 close to the extraction electrode 220 may be partially removed, so that the end portion of the upper electrode layer 400 close to the extraction electrode 220 is exposed to form a connection end of the upper electrode layer 400. Thus, the connection terminal and the extraction electrode can be electrically connected by using a conductive material, and the upper electrode layer 400 can be electrically connected to the extraction electrode 220 through the connection terminal.
It should be noted that, in this embodiment, the process of preparing the passivation layer 500 and the upper electrode layer 400 sequentially includes: a first etching process is performed on the passivation material layer 500a, a second etching process is performed on the upper electrode material layer 400a, and a third etching process is also performed on the passivation layer 500 in order to expose the connection terminal of the upper electrode layer 400.
However, in other embodiments, the upper electrode layer exposing the connection terminal may be directly formed. For example, the formation process of the passivation layer 500 and the upper electrode layer 400 may further include the following steps.
The method comprises the following steps of firstly, forming a first mask layer on the passivation material layer, and etching the passivation material layer by taking the first mask layer as a mask to form the passivation layer, wherein at the moment, a part of the upper electrode material layer is correspondingly exposed.
And a second step of forming a second mask layer, wherein the second mask layer covers the passivation layer, and the end part of the second mask layer close to the extraction electrode 220 further extends from the passivation layer to the upper electrode material layer so as to extend to cover part of the upper electrode material layer.
At this time, at least one end portion of the second mask layer (including an end portion corresponding to a subsequently formed suspended portion; e.g., an end portion distant from an extraction electrode) may also be made flush or nearly flush with an end portion of the passivation layer.
And then, etching the upper electrode material layer by taking the second mask layer as a mask to form the upper electrode layer, and removing the second mask layer to expose the end part of the upper electrode layer close to the extraction electrode.
Similarly, the upper electrode material layer may be etched by an anisotropic etching process, so that at least one end of the formed upper electrode layer is flush or nearly flush with an end of the passivation layer. For example, when the at least one end portion of the upper electrode layer 400 is recessed with respect to an end portion of the passivation layer 500, the recess value is 0.5 μm or less; alternatively, when the at least one end portion of the upper electrode layer 400 extends out with respect to an end portion of the passivation layer 500, the extension value of the extension may be less than or equal to 0.5 μm. Further, it can be considered that when the at least one end portion of the upper electrode layer 400 is leveled with respect to an end portion of the passivation layer 500, the recessing value is equal to 0 or the extending value is equal to 0.
Note that, the at least one end portion of the upper electrode layer described herein includes: corresponding to the end where the suspended portion is subsequently formed. For example, the end remote from the extraction electrode.
That is, in other embodiments, the process of preparing the passivation layer 500 and the upper electrode layer 400 sequentially includes: a first etching process is performed on the passivation material layer 500a, and a second etching process is performed on the upper electrode material layer 400a, wherein the end of the formed upper electrode layer 400 close to the extraction electrode is directly exposed. Therefore, one etching step can be reduced, and the process is simplified. Particularly, the etching parameters adopted by the etching process for the passivation material layer and the etching process for the upper electrode material layer are usually different from each other (including different etchant and etching equipment), and based on this, in other embodiments, the upper electrode layer with the exposed end portion can be directly formed by sequentially etching the passivation material layer and the upper electrode material layer, so that the conversion times of the etchant and the etching equipment are reduced.
Referring next to fig. 3d, the piezoelectric material layer 300 is etched to form a contact window 310 in the piezoelectric material layer 300, wherein the contact window 310 exposes the extraction electrode 220.
As described above, in the present embodiment, the extraction electrode 220 is used to be electrically connected to the upper electrode layer 400. Based on this, the contact window 310 may be formed on one side of the connection end of the upper electrode layer 400, so that the contact window 310 is close to the connection end of the upper electrode layer 400. In this way, in the subsequent process, through the contact window 310, not only the contact pad electrically connected to the extraction electrode 220 can be prepared, but also the upper electrode layer 400 can be electrically connected to the extraction electrode 220 and the contact pad at the same time.
In step S200, referring to fig. 3e specifically, a lift-off process is performed to form a contact pad 600 on the extraction electrode 220, wherein the contact pad 600 is electrically connected to the extraction electrode 220 and is used for electrically extracting the upper electrode layer 400 or the lower electrode layer 210.
Specifically, the method for forming the contact pad 600 using the lift-off process may include the following steps.
Step one, forming a photoresist layer, wherein the photoresist layer covers the piezoelectric material layer 300 and the passivation layer 500, and an opening is further formed in the photoresist layer, and the contact window 310 is exposed through the opening of the photoresist layer, so that the extraction electrode 220 in the contact window 310 is correspondingly exposed.
In this embodiment, the extraction electrode 220 is used to electrically connect the upper electrode layer 400, so that the connection end of the upper electrode layer 400 and the extraction electrode 220 are exposed in the same opening of the photoresist layer, and thus the connection end of the upper electrode layer 400 and the extraction electrode 220 can be electrically connected when a conductive material is formed subsequently.
Step two, a conductive material layer is formed, the conductive material layer covers the photoresist layer, and the conductive material layer is further formed in the contact window 310 exposed in the opening to be connected with the extraction electrode 220. In this embodiment, the conductive material layer fills the contact window 310 to cover the extraction electrode 220. The forming method of the conductive material layer includes, for example, an evaporation process, and the material of the conductive material layer 800 includes, for example, at least one of gold (Au) or copper (Cu).
Further, since the opening of the photoresist layer simultaneously exposes the connection end of the upper electrode layer 400 and the extraction electrode 220 in the contact window, the portion of the conductive material layer corresponding to the opening correspondingly connects the connection end of the upper electrode layer 400 and the extraction electrode 220.
And step three, stripping the photoresist layer to remove the portion of the conductive material layer covering the photoresist layer, and retaining the portion of the conductive material layer corresponding to the opening to form a contact pad 600, wherein the contact pad 600 is electrically connected to the upper electrode layer or the lower electrode layer. In this embodiment, the contact pad 600 is further electrically connected to the upper electrode layer 400.
Specifically, in the process of stripping the photoresist layer, a stripping solution is usually sprayed on the photoresist layer at a relatively high spraying pressure, so as to achieve the stripping process of the photoresist layer. It should be noted that, in the conventional process, the suspended portion of the passivation layer 500 is preferentially prepared before the photoresist layer is formed, and therefore, when the photoresist layer is stripped, a larger spraying pressure may directly act on the suspended portion of the passivation layer 500, which may easily cause the suspended portion of the passivation layer 500 to break.
However, in this embodiment, the passivation layer 500 has not been formed with a free space before the photoresist layer is stripped, and at this time, even if the photoresist layer is stripped by a large spraying pressure, the free space of the passivation layer does not collapse. Based on this, in an alternative scheme, the spraying pressure of the stripping liquid can be further increased so as to improve the removal efficiency of the photoresist layer.
It should be noted that the photoresist layer is usually formed by a coating process, and in this case, for example, in the conventional process, the photoresist layer will easily fill the exposed gap, for example, as shown in fig. 1b, when the photoresist layer is directly formed on the passivation layer, the photoresist layer is very easy to fill the space below the suspended portion, which may cause a problem that the photoresist material in the space below the suspended portion is difficult to be removed when the photoresist layer is subsequently removed. Compared with the prior art, in the embodiment, the passivation layer does not form the suspended portion before the photoresist layer is formed, and therefore, the photoresist material does not fill the lower space of the passivation layer when the photoresist layer is formed, so that the problem of incomplete removal of the photoresist layer can be effectively solved.
Step S300, specifically referring to fig. 3f, laterally eroding at least one end portion of the upper electrode layer 400, so that the at least one end portion of the upper electrode layer 400 is retracted relative to an end portion of the passivation layer 500. Wherein the recession value of the at least one end portion of the upper electrode layer 400 recessed with respect to the end portion of the passivation layer 500 is, for example, 0.7 μm or more, and more specifically, the recession value of the end portion of the upper electrode layer 400 recessed with respect to the end portion of the passivation layer 500 may be further 0.7 μm to 2.5 μm.
At this time, an end portion of the passivation layer 500 extending relative to the upper electrode layer 400 may be used to form a suspended portion 510, and the suspended portion 510 is suspended above the piezoelectric material layer 300.
Specifically, the upper electrode layer 400 and the contact pad 600 may be formed of different materials, so that the contact pad 600 is not affected when the end portion of the upper electrode layer 400 is laterally eroded. For example, the material of the upper electrode layer 400 may include molybdenum, and the material of the contact pad may include gold and/or copper. And, the end portion of the upper electrode layer 400 may be laterally eroded using a wet etching process, wherein an etchant of the wet etching process includes, for example, nitric acid.
In this embodiment, for example, an end portion of the upper electrode layer 400 opposite to the connection end may be laterally eroded, in which case, the end portion of the passivation layer 500 opposite to the connection end is correspondingly made to form a suspended portion 510. It should be noted that, since at least a part of the end of the passivation layer 500 forms the suspended portion 510, when the semiconductor device is applied to a bulk acoustic wave filter, a lateral acoustic wave excited in the bulk acoustic wave filter can be more easily scattered, so that a lateral mode harmful to the device is not easily excited, energy loss due to lateral excitation is reduced, and the quality factor (Q value) of the bulk acoustic wave filter is advantageously improved.
In addition, in a specific embodiment, the method for forming the semiconductor device further includes: a cavity is formed in the substrate 100 under the lower electrode layer 210. Specifically, the method for forming the cavity may specifically include:
first, before forming the lower electrode layer, a sacrificial layer is filled in the substrate 100;
next, the steps S100 to S300 described above are sequentially performed, and in the process of performing the steps S100 to S300, a through hole is further formed in the piezoelectric material layer 300, the through hole penetrating the piezoelectric material layer 300 to extend to the sacrificial layer;
then, after step S300 is performed, the sacrificial layer may be removed through the through hole to form a cavity in the substrate 100.
Of course, in other embodiments, a through hole may be formed in a portion of the substrate 100 below the sacrificial layer, and a top of the through hole in the substrate 100 may extend to the sacrificial layer, so that the space of the sacrificial layer may be released from the back surface of the substrate 100 to form the cavity. Based on the above forming method, the present embodiment further provides a semiconductor device, which can be specifically shown in fig. 3f, and the semiconductor device includes:
a substrate 100;
an extraction electrode 220 formed on the substrate 100;
a lower electrode layer 210 formed on the substrate 100;
a piezoelectric material layer 300 formed on the substrate 100 and covering the lower electrode layer 210 and the extraction electrode 220, and having a contact window formed therein, the bottom of the contact window extending to the extraction electrode 220;
an upper electrode layer 400 formed on the piezoelectric material layer 300, wherein projected images of the lower electrode layer 400 and the upper electrode layer 210 projected on the same horizontal plane at least partially overlap;
a passivation layer 500 formed on the upper electrode layer 400, wherein the passivation layer 500 has a suspended portion 510 extending from the upper electrode layer 400, and the suspended portion 510 is suspended above the piezoelectric material layer 300; and the number of the first and second groups,
a contact pad 600 at least formed in the contact window to electrically connect with the extraction electrode 220 for electrically extracting the upper electrode layer or the lower electrode layer.
In this embodiment, the extraction electrode 220 is electrically connected to the upper electrode layer 400. At this time, an end portion of the upper electrode layer 400 near the contact window may be further exposed from the passivation layer 500, and the contact pad 600 further covers the end portion of the upper electrode layer 400 while filling the contact window to electrically connect with the extraction electrode 220, thereby electrically connecting the upper electrode layer 400 and the contact pad 600.
In summary, in the method for forming a semiconductor device in this embodiment, the upper electrode layer may be formed by using an anisotropic etching process before the lift-off process is performed, so that a portion of the passivation layer above the upper electrode layer is not covered by the floating portion, and thus, when the lift-off process is performed, the problem that the floating portion of the passivation layer is damaged does not occur. Therefore, when the photoresistive layer is stripped, the spraying pressure of the stripping liquid can be further increased so as to improve the stripping efficiency of the photoresistive layer and avoid the phenomenon that the photoresistive layer is not completely removed.
In addition, in the conventional process, the passivation layer has been formed with a free space before the lift-off process is performed, so that the photoresist material easily fills the space under the free space when the lift-off process is performed, thereby making it difficult to remove the photoresist material filled under the free space. Compared with the conventional process, in the embodiment, since the passivation layer is not provided with the suspended part during the stripping process, the phenomenon that the photoresist material fills the gap below the passivation layer does not exist, and the problem that the photoresist layer is not completely removed is effectively solved.
It should be noted that, although the present invention has been described with reference to the preferred embodiments, the present invention is not limited to the embodiments. It will be apparent to those skilled in the art from this disclosure that many changes and modifications can be made, or equivalents modified, in the embodiments of the invention without departing from the scope of the invention. Therefore, any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present invention are still within the protection scope of the technical solution of the present invention, unless the content of the technical solution of the present invention is departed from.
It should be further understood that the terms "first," "second," "third," and the like in the description are used for distinguishing between various components, elements, steps, and the like, and are not intended to imply a logical or sequential relationship between various components, elements, steps, or the like, unless otherwise indicated or indicated.
It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only, and is not intended to limit the scope of the present invention. It must be noted that, as used herein and in the appended claims, the singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise. For example, reference to "a step" or "an apparatus" means a reference to one or more steps or apparatuses and may include sub-steps as well as sub-apparatuses. All conjunctions used should be understood in the broadest sense. And, the word "or" should be understood to have the definition of a logical "or" rather than the definition of a logical "exclusive or" unless the context clearly dictates otherwise. Further, implementation of the methods and/or apparatus of embodiments of the present invention may include performing the selected task manually, automatically, or in combination.

Claims (12)

1. A method of forming a semiconductor device, comprising:
providing a substrate, wherein a lower electrode layer and an extraction electrode are formed on the substrate, a piezoelectric material layer is further formed on the lower electrode layer and the extraction electrode, an upper electrode layer and a passivation layer are sequentially formed on the piezoelectric material layer, and a contact window is further formed in the piezoelectric material layer and exposes the extraction electrode;
performing a stripping process to form a contact pad on the extraction electrode, wherein the contact pad is electrically connected with the extraction electrode and is used for electrically extracting the upper electrode layer or the lower electrode layer; and the number of the first and second groups,
and laterally eroding at least one end part of the upper electrode layer so as to enable the at least one end part of the upper electrode layer to be retracted relative to the end part of the passivation layer, and forming a suspended part by utilizing the end part of the passivation layer extending relative to the upper electrode layer.
2. The method for forming a semiconductor device according to claim 1, wherein the extraction electrode is used for electrically extracting the upper electrode layer; and the passivation layer exposes the connecting end of the upper electrode layer close to the extraction electrode, and the contact pad is electrically connected with the connecting end and the extraction electrode.
3. The method for forming a semiconductor device according to claim 2, wherein the method for forming the upper electrode layer and the passivation layer comprises: sequentially forming an upper electrode material layer and a passivation material layer on the piezoelectric material layer, etching the passivation material layer to form a passivation layer, and etching the upper electrode material layer by taking the passivation layer as a mask to form an upper electrode layer;
and, after etching the upper electrode material layer to form the upper electrode layer, further comprising: and partially removing the end part of the passivation layer close to the extraction electrode so as to expose the connecting end of the upper electrode layer close to the extraction electrode.
4. The method for forming a semiconductor device according to claim 2, wherein the method for forming the upper electrode layer and the passivation layer comprises:
sequentially forming an upper electrode material layer and a passivation material layer on the piezoelectric material layer;
forming a first mask layer on the passivation material layer, and etching the passivation material layer by taking the first mask layer as a mask to form the passivation layer and expose part of the upper electrode material layer;
forming a second mask layer, wherein the second mask layer covers the passivation layer, and the end part of the second mask layer close to the extraction electrode also extends to cover part of the upper electrode material layer; and the number of the first and second groups,
and etching the upper electrode material layer by taking the second mask layer as a mask to form the upper electrode layer, and removing the second mask layer to expose the connecting end of the upper electrode layer close to the extraction electrode.
5. The method of forming a semiconductor device according to claim 1, wherein the method of performing a lift-off process to form the contact pad comprises;
forming a light resistance layer, wherein an opening is formed in the light resistance layer, and the contact window is exposed out of the opening of the light resistance layer;
forming a conductive material layer covering the photoresist layer, and the conductive material layer is further formed in a contact window exposed in the opening to be connected with the extraction electrode;
and stripping the photoresist layer to remove the part of the conductive material layer covering the photoresist layer and reserve the part of the conductive material layer corresponding to the opening to form the contact pad.
6. The method for forming a semiconductor device according to claim 5, wherein the passivation layer exposes a connection end of the upper electrode layer near the extraction electrode;
wherein, when the photoresist layer is formed, the contact window and the connecting end of the upper electrode layer are exposed in the opening;
and when the conductive material layer is formed, the conductive material layer also covers the connection end of the upper electrode layer so as to electrically connect the connection end and the contact pad.
7. The method of forming a semiconductor device according to claim 1, wherein laterally eroding the upper electrode layer comprises: and laterally eroding the upper electrode layer by utilizing a wet etching process.
8. The method for forming a semiconductor device according to claim 7, wherein an etchant for the wet etching process comprises nitric acid.
9. The method for forming a semiconductor device according to claim 1, wherein before the lift-off process is performed, the at least one end portion of the upper electrode layer is recessed with respect to an end portion of the passivation layer, and a value of the recess is 0.5 μm or less; or, the at least one end portion of the upper electrode layer extends out with respect to an end portion of the passivation layer, and an extension value of the extension is 0.5 μm or less.
10. The method for forming a semiconductor device according to claim 1, wherein at least one end portion of the upper electrode layer is laterally eroded so that a value of recession of the at least one end portion of the upper electrode layer with respect to an end portion of the passivation layer is 0.7 μm or more.
11. The method for forming a semiconductor device according to claim 1, wherein a material of the upper electrode layer includes molybdenum, and a material of the contact pad includes gold and/or copper.
12. A semiconductor device manufactured by the forming method according to any one of claims 1 to 11, comprising:
a substrate;
an extraction electrode formed on the substrate;
a lower electrode layer formed on the substrate;
the piezoelectric material layer covers the lower electrode layer and the extraction electrode, a contact window is further formed in the piezoelectric material layer, and the bottom of the contact window extends to the extraction electrode;
an upper electrode layer formed on the piezoelectric material layer;
a passivation layer formed on the upper electrode layer and having a suspended portion extending from the upper electrode layer;
and the contact pad is at least formed in the contact window and is electrically connected with the extraction electrode so as to be used for electrically extracting the upper electrode layer or the lower electrode layer.
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