TWI747362B - Piezoelectric micromachined ultrasonic transducer and method of fabricating the same - Google Patents
Piezoelectric micromachined ultrasonic transducer and method of fabricating the same Download PDFInfo
- Publication number
- TWI747362B TWI747362B TW109122700A TW109122700A TWI747362B TW I747362 B TWI747362 B TW I747362B TW 109122700 A TW109122700 A TW 109122700A TW 109122700 A TW109122700 A TW 109122700A TW I747362 B TWI747362 B TW I747362B
- Authority
- TW
- Taiwan
- Prior art keywords
- layer
- ultrasonic transducer
- substrate
- micromachined ultrasonic
- piezoelectric
- Prior art date
Links
Images
Landscapes
- Transducers For Ultrasonic Waves (AREA)
Abstract
Description
本揭露涉及微機電系統(Micro Electro Mechanical System,MEMS)的技術領域,特別是涉及一種壓電微機械超聲波換能器(PMUT)及其製作方法。 The present disclosure relates to the technical field of Micro Electro Mechanical System (MEMS), and particularly relates to a piezoelectric micro mechanical ultrasonic transducer (PMUT) and a manufacturing method thereof.
在過去的幾十年裡,微機械超聲波換能器(Micro Machined Transducer,MUTs)受到了廣泛的研究,並成為各種消費電子產品的重要組成,例如是指紋感測器、鄰近(proximity)感測器和手勢感測器中的組成部件。一般來說,MUTs可以被分為兩大類,例如是電容式微機械超聲波換能器(CMUTs)和壓電式微機械超聲波換能器(PMUTs)。對於典型的壓電式微機械超聲波換能器而言,壓電式微機械超聲波換能器包括由彈性材料、電極和壓電材料所構成的膜層,此膜層會被設置在作為聲波諧振器的空腔上,以提升壓電式微機械超聲波換能器的聲學性能。在壓電式微機械超聲波換能器運作的過程中,經由膜層的振動而產生的超聲波會從壓電式微機械超聲波換能器而被傳遞至目標物,然後壓電式微機械超聲波換能器可以偵測超聲波撞擊目標物後而產生的反射聲波。 In the past few decades, Micro Machined Transducers (MUTs) have been extensively studied and have become an important component of various consumer electronics products, such as fingerprint sensors and proximity (proximity) sensing. Component parts of the device and gesture sensor. Generally speaking, MUTs can be divided into two categories, such as capacitive micromachined ultrasonic transducers (CMUTs) and piezoelectric micromachined ultrasonic transducers (PMUTs). For a typical piezoelectric micromechanical ultrasonic transducer, the piezoelectric micromechanical ultrasonic transducer includes a film layer composed of elastic materials, electrodes, and piezoelectric materials. This film layer is set on the acoustic resonator. On the cavity, to improve the acoustic performance of the piezoelectric micromachined ultrasonic transducer. During the operation of the piezoelectric micro-machined ultrasonic transducer, the ultrasonic waves generated by the vibration of the film will be transmitted from the piezoelectric micro-machined ultrasonic transducer to the target, and then the piezoelectric micro-machined ultrasonic transducer can Detect the reflected sound waves produced by ultrasonic waves hitting the target.
通常,壓電式微機械超聲波換能器會在膜層的彎曲共振頻率下運作,此彎曲共振頻率可透過選擇正確的材料、膜的尺寸和厚度來決定。因此,單個壓電式微機械超聲波換能器的共振頻率的良好匹配是正常運作的必要條 件。然而,由於位於膜層下方的空腔通常是透過蝕刻基底的背面而形成,因而於基底正面形成空腔開口,以用於定義膜層的大小。此空腔開口尺寸在同一晶圓內的不同區域或是不同晶圓之間可能會產生相當大的變異,因而不可避免地導致了各壓電式微機械超聲波換能器的共振頻率的變異。 Generally, the piezoelectric micromachined ultrasonic transducer will operate at the bending resonance frequency of the film. The bending resonance frequency can be determined by selecting the correct material, the size and thickness of the film. Therefore, a good match of the resonance frequency of a single piezoelectric micromachined ultrasonic transducer is a necessary condition for normal operation. Pieces. However, since the cavity under the film layer is usually formed by etching the back surface of the substrate, a cavity opening is formed on the front surface of the substrate to define the size of the film layer. The size of the cavity opening may vary greatly in different regions within the same wafer or between different wafers, which inevitably leads to the variation of the resonance frequency of various piezoelectric micromachined ultrasonic transducers.
因此,需要提供一種改良的壓電式微機械超聲波換能器及其製作方法,使得壓電式微機械超聲波換能器中的膜層尺寸可以被精確控制。 Therefore, there is a need to provide an improved piezoelectric micromechanical ultrasonic transducer and a manufacturing method thereof, so that the film layer size in the piezoelectric micromechanical ultrasonic transducer can be accurately controlled.
有鑒於此,為了提升壓電式微機械超聲波換能器的共振頻率的均勻性,有必要提出一種改良的壓電式微機械超聲波換能器及其製作方法。 In view of this, in order to improve the uniformity of the resonance frequency of the piezoelectric micromachined ultrasonic transducer, it is necessary to propose an improved piezoelectric micromachined ultrasonic transducer and a manufacturing method thereof.
根據本揭露的一實施例,壓電式微機械超聲波換能器包括基底、阻擋結構和膜層,其中基底和阻擋結構由相同的材料組成。基底包括穿透基底的空腔,阻擋結構從基底的頂面突出並圍繞空腔的邊緣。膜層設置在空腔上並附著於阻擋結構。 According to an embodiment of the present disclosure, the piezoelectric micromachined ultrasonic transducer includes a substrate, a barrier structure and a film layer, wherein the substrate and the barrier structure are composed of the same material. The base includes a cavity penetrating the base, and the blocking structure protrudes from the top surface of the base and surrounds the edge of the cavity. The film layer is arranged on the cavity and attached to the barrier structure.
根據本揭露的另一實施例,公開了一種製作壓電式微機械超聲波換能器的方法,包括以下步驟。首先蝕刻基底,形成從基底突出的阻擋結構,然後在基底上形成犧牲層,其中阻擋結構會暴露出於犧牲層。然後,在阻擋結構和犧牲層上形成膜層。然後形成穿透基底的空腔,以暴露出犧牲層的一部分。隨後,藉由使用阻擋結構作為蝕刻停止結構,以去除暴露於空腔的犧牲層的一部分。 According to another embodiment of the present disclosure, a method for manufacturing a piezoelectric micromechanical ultrasonic transducer is disclosed, which includes the following steps. The substrate is first etched to form a barrier structure protruding from the substrate, and then a sacrificial layer is formed on the substrate, wherein the barrier structure is exposed from the sacrificial layer. Then, a film layer is formed on the barrier structure and the sacrificial layer. Then, a cavity penetrating the substrate is formed to expose a part of the sacrificial layer. Subsequently, a part of the sacrificial layer exposed to the cavity is removed by using the barrier structure as an etch stop structure.
根據本揭露的上述實施例,阻擋結構是一種突出於基底頂面的結構,透過控制阻擋結構的位置,可以調整膜層的尺寸。由於阻擋結構是透過蝕刻基底而形成的,因此阻擋結構除了可以緊密地附著於基底,而不會自基底剝離,亦可具有垂直的側壁。藉由上述,可有效提升壓電式微機械超聲波換能器 的可靠度和電氣性能。 According to the above-mentioned embodiment of the present disclosure, the barrier structure is a structure protruding from the top surface of the substrate, and the size of the film layer can be adjusted by controlling the position of the barrier structure. Since the barrier structure is formed by etching the substrate, the barrier structure can not only be tightly attached to the substrate without peeling off from the substrate, but can also have vertical sidewalls. Through the above, the piezoelectric micro-machined ultrasonic transducer can be effectively improved Reliability and electrical performance.
100:壓電微機械超聲波換能器 100: Piezoelectric micromachined ultrasonic transducer
102:基底 102: Base
102s:頂面 102s: top surface
10)4:阻擋結構 10) 4: Blocking structure
104s:頂面 104s: top surface
106:膜層 106: Membrane
108:主體部分 108: The main part
110:基部 110: base
112:截斷部 112: Truncated part
114:第一接觸墊 114: first contact pad
116:第二接觸墊 116: second contact pad
120:空腔 120: Cavity
120e:邊緣 120e: Edge
122:第一部分 122: Part One
122s:頂面 122s: top surface
124:第二部分 124: Part Two
124s:頂面 124s: top surface
126:犧牲層 126: Sacrifice Layer
130:基層 130: grassroots
132:介電層 132: Dielectric layer
134:底導電層 134: bottom conductive layer
136:壓電層 136: Piezo Layer
138:頂導電層 138: Top conductive layer
140:鈍化層 140: passivation layer
152:截斷部 152: truncated part
200:方法 200: method
202:步驟 202: step
204:步驟 204: Step
206:步驟 206: Step
208:步驟 208: Step
210:步驟 210: Step
212:步驟 212: Step
D:距離 D: distance
O:開口 O: opening
為了使下文更容易被理解,在閱讀本揭露時可同時參考圖式及其詳細文字說明。透過本文中之具體實施例並參考相對應的圖式,俾以詳細解說本揭露之具體實施例,並用以闡述本揭露之具體實施例之作用原理。此外,為了清楚起見,圖式中的各特徵可能未按照實際的比例繪製,因此某些圖式中的部分特徵的尺寸可能被刻意放大或縮小。 In order to make the following easier to understand, the drawings and detailed text descriptions can be referred to when reading this disclosure. Through the specific embodiments in this text and with reference to the corresponding drawings, the specific embodiments of the present disclosure are explained in detail, and the principles of the specific embodiments of the present disclosure are explained. In addition, for the sake of clarity, the features in the drawings may not be drawn according to the actual scale, so the size of some features in some drawings may be deliberately enlarged or reduced.
第1圖是根據本揭露的一實施例所繪示的壓電微機械超聲波換能器(PMUT)的俯視示意圖。 FIG. 1 is a schematic top view of a piezoelectric micromachined ultrasonic transducer (PMUT) according to an embodiment of the disclosure.
第2圖是根據本揭露的一實施例沿著第1圖A-A'切線所繪示的剖面示意圖。 FIG. 2 is a schematic cross-sectional view taken along the line AA′ in FIG. 1 according to an embodiment of the present disclosure.
第3圖是根據本揭露的一實施例所繪示的在基底上形成阻擋結構後的示意圖。 FIG. 3 is a schematic diagram after a barrier structure is formed on a substrate according to an embodiment of the disclosure.
第4圖是根據本揭露的一實施例所繪示的在基底上形成犧牲層後的剖面示意圖。 FIG. 4 is a schematic cross-sectional view after a sacrificial layer is formed on a substrate according to an embodiment of the disclosure.
第5圖是根據本揭露的一實施例所繪示的在阻擋結構和犧牲層上形成基層後的剖面示意圖。 FIG. 5 is a schematic cross-sectional view after forming a base layer on the barrier structure and the sacrificial layer according to an embodiment of the disclosure.
第6圖是根據本揭露的一實施例所繪示的在基層上形成堆疊層從而形成膜層後的剖面示意圖。 FIG. 6 is a schematic cross-sectional view after forming a stacked layer on a base layer to form a film layer according to an embodiment of the disclosure.
第7圖是根據本揭露的一實施例所繪示的形成接觸墊後的剖面示意圖。 FIG. 7 is a schematic cross-sectional view after forming a contact pad according to an embodiment of the disclosure.
第8圖是根據本揭露的一實施例所繪示的在膜層中形成截斷部後的剖面示意圖。 FIG. 8 is a schematic cross-sectional view after a cut-off portion is formed in the film according to an embodiment of the disclosure.
第9圖是根據本揭露的一實施例所繪示的形成穿透基底的空腔後的剖面示 意圖。 Figure 9 is a cross-sectional view after a cavity penetrating the substrate is formed according to an embodiment of the disclosure intention.
第10圖是根據本揭露的一實施例所繪示的製作壓電微機械超聲波換能器的方法流程圖。 FIG. 10 is a flowchart of a method for manufacturing a piezoelectric micromachined ultrasonic transducer according to an embodiment of the disclosure.
本揭露提供了數個不同的實施例,可用於實現本揭露的不同特徵。為簡化說明起見,本揭露也同時描述了特定構件與設置的範例。提供這些實施例的目的僅在於示意,而非予以任何限制。舉例而言,下文中針對「第一特徵形成在第二特徵上或上方」的敘述,其可以是指「第一特徵與第二特徵直接接觸」,也可以是指「第一特徵與第二特徵間另存在有其他特徵」,致使第一特徵與第二特徵並不直接接觸。此外,本揭露中的各種實施例可能使用重複的參考符號和/或文字註記。使用這些重複的參考符號與註記是為了使敘述更簡潔和明確,而非用以指示不同的實施例及/或配置之間的關聯性。 The present disclosure provides several different embodiments, which can be used to implement different features of the present disclosure. To simplify the description, this disclosure also describes examples of specific components and settings. The purpose of providing these embodiments is only for illustration, and not for any limitation. For example, the following description of "the first feature is formed on or above the second feature" can mean "the first feature is in direct contact with the second feature", or it can mean "the first feature is in direct contact with the second feature". There are other features among the features", so that the first feature and the second feature are not in direct contact. In addition, various embodiments in the present disclosure may use repeated reference symbols and/or text annotations. These repeated reference symbols and notes are used to make the description more concise and clear, rather than to indicate the relevance between different embodiments and/or configurations.
另外,針對本揭露中所提及的空間相關的敘述詞彙,例如:「在...之下」,「低」,「下」,「上方」,「之上」,「下」,「頂」,「底」和類似詞彙時,為便於敘述,其用法均在於描述圖式中一個元件或特徵與另一個(或多個)元件或特徵的相對關係。除了圖式中所顯示的擺向外,這些空間相關詞彙也用來描述半導體裝置在使用中以及運作時的可能擺向。隨著半導體裝置的擺向的不同(旋轉90度或其它方位),用以描述其擺向的空間相關敘述亦應透過類似的方式予以解釋。 In addition, regarding the space-related narrative vocabulary mentioned in this disclosure, such as: "below", "low", "below", "above", "above", "below", "top" ", "base" and similar words, for ease of description, their usage is to describe the relative relationship between one element or feature and another (or more) elements or features in the drawing. In addition to the swing outward shown in the diagram, these spatially related words are also used to describe the possible swing directions of the semiconductor device during use and operation. As the swing direction of the semiconductor device is different (rotated by 90 degrees or other orientations), the space-related narrative used to describe its swing direction should also be explained in a similar way.
雖然本揭露使用第一、第二、第三等等用詞,以敘述種種元件、部件、區域、層、及/或區塊(section),但應瞭解此等元件、部件、區域、層、及/或區塊不應被此等用詞所限制。此等用詞僅是用以區分某一元件、部件、區域、層、及/或區塊與另一個元件、部件、區域、層、及/或區塊,其本身並不意含及 代表該元件有任何之前的序數,也不代表某一元件與另一元件的排列順序、或是製作方法上的順序。因此,在不背離本揭露之具體實施例之範疇下,下列所討論之第一元件、部件、區域、層、或區塊亦可以第二元件、部件、區域、層、或區塊之詞稱之。 Although the present disclosure uses terms such as first, second, and third to describe various elements, components, regions, layers, and/or sections, it should be understood that these elements, components, regions, layers, And/or blocks should not be restricted by these terms. These terms are only used to distinguish a certain element, component, region, layer, and/or block from another element, component, region, layer, and/or block, and do not mean and It means that the component has any previous ordinal number, and does not represent the order of arrangement of a certain component and another component, or the order of the manufacturing method. Therefore, without departing from the scope of the specific embodiments of the present disclosure, the first element, component, region, layer, or block discussed below can also be referred to as the second element, component, region, layer, or block Of.
本揭露中所提及的「約」或「實質上」之用語通常表示在一給定值或範圍的20%之內,較佳是10%之內,且更佳是5%之內,或3%之內,或2%之內,或1%之內,或0.5%之內。應注意的是,說明書中所提供的數量為大約的數量,亦即在沒有特定說明「約」或「實質上」的情況下,仍可隱含「約」或「實質上」之含義。 The term "about" or "substantially" mentioned in this disclosure usually means within 20% of a given value or range, preferably within 10%, and more preferably within 5%, or Within 3%, or within 2%, or within 1%, or within 0.5%. It should be noted that the quantity provided in the manual is approximate, that is, the meaning of "approximate" or "substantial" can still be implied when there is no specific description of "approximate" or "substantial".
於下文製程/流程圖中所揭露的流程圖塊的特定順序或層次可以理解為示例性的說明。可以理解的是,根據不同設計偏好,此製程/流程圖中所揭露的流程圖塊的特定順序或層次可以被重新安排。此外,部分流程圖塊可以被合併或省略。隨附的方法請求項以示例的順序表示各流程圖塊中的要件,但此不代表此方法請求項被限定為此特定順序或層次。 The specific sequence or level of the flowchart blocks disclosed in the process/flow chart below can be understood as an exemplary description. It is understandable that, according to different design preferences, the specific order or hierarchy of the flowchart blocks disclosed in this process/flow chart can be rearranged. In addition, part of the flowchart blocks can be combined or omitted. The attached method request items show the elements in each flowchart block in the order of examples, but this does not mean that the method request items are limited to this specific order or level.
雖然下文係藉由具體實施例以描述本揭露的發明,然而本揭露的發明原理亦可應用至其他的實施例。此外,為了不致使本揭露之精神晦澀難懂,特定的細節會被予以省略,該些被省略的細節係屬於所屬技術領域中包括通常知識者的知識範圍。 Although specific embodiments are used below to describe the invention of the present disclosure, the principles of the invention of the present disclosure can also be applied to other embodiments. In addition, in order not to make the spirit of this disclosure obscure, specific details will be omitted, and the omitted details belong to the scope of knowledge of ordinary knowledgeable persons in the technical field.
第1圖是根據本揭露的一實施例所繪示的壓電微機械超聲波換能器(PMUT)的俯視示意圖。參考第1圖,壓電微機械超聲波換能器100至少包括基底102、阻擋結構104、膜層106、截斷部112、第一接觸墊114和第二接觸墊116。根據本揭露的一實施例,阻擋結構104可以是從基底102的頂面突出的環形結構,使得膜層106的一部分可以附著至阻擋結構104。阻擋結構104的形狀不限於此,阻擋結構104可以是沿著膜層106的邊緣而設置的多邊形或弧形。膜層106可以包
括設置在空腔(未示出)上方的主體部分108和設置在主體部分108周邊的基部110。主體部分108的形狀可以由截斷部112的形狀加以定義,並且可以是任何形狀,例如圓形、扇形或多邊形。阻擋結構104可以沿著截斷部112的周邊以及主體部分108的周邊設置。膜層106的主體部分108可以是包括電極和壓電材料的多層結構。基部110附著到阻擋結構104,並且可以被視為從膜層106的主體部分108延伸出的部分。第一接觸墊114和第二接觸墊116可以設置在膜層106的相對側,其可以分別電耦合到膜層106的電極。此外,為了避免第一接觸墊114和第二接觸墊116之間產生不預期的寄生電容,第一接觸墊114和第二接觸墊116的尺寸可以盡可能的縮小,但不限於此。根據本揭露的一實施例,第一接觸墊114和第二接觸墊116可以設置在膜層106的同一側或者任何位置,只要第一接觸墊114和第二接觸墊116可以電耦合到膜層106的電極即可。電耦合到第一接觸墊114和第二接觸墊116的導電跡線(未示出)可以額外被設置在基底102上,以便將電訊號傳輸到膜層106中或從膜層106中傳輸出去。在壓電微機械超聲波換能器100的運作過程中,當聲波對於膜層106施加聲壓或者電訊號被施加至膜層106時,膜層106,尤其是膜層106的主體部分108,可以振動。透過使用阻擋結構104,膜層106的尺寸和位置可以被精確獨立定義,而不論膜層106下方的空腔尺寸和位置。因此,可以有效提升各壓電微機械超聲波換能器100的共振頻率均勻性。
FIG. 1 is a schematic top view of a piezoelectric micromachined ultrasonic transducer (PMUT) according to an embodiment of the disclosure. Referring to FIG. 1, the piezoelectric micromachined
第2圖是根據本揭露的一實施例沿第1圖的A-A'切線所繪示的剖面示意圖。參照第2圖,該阻擋結構104可以從基底102的頂面102s突出。基底102可以是半導體基底,例如塊矽基底,但不限於此。基底102和阻擋結構104可以由相同的材料所組成,如單晶矽、多晶矽、非晶矽、玻璃、陶瓷材料或其他合適的材料。根據本揭露的一實施例,基底102可以是SOI基底。犧牲層126的組成係不同於基底102的組成,阻擋結構104會被設置於基底102上,犧牲層126會環繞阻擋結構104。根據本揭露的一實施例,在基底102和/或阻擋結構104係由半導體材
料(如Si)所組成的情況下,犧牲層126可能是介電層,如氧化矽(SiOx)或二氧化矽(SiO2)。此外,犧牲層126的頂面可以和阻擋結構104的頂面實質上切齊,使得設置在犧牲層126和阻擋結構104上的層可具有平坦的底面。參考第2圖,雖然阻擋結構104的寬度遠小於犧牲層126的寬度,但是根據本揭露的另一實施例,阻擋結構104的寬度可以被設計為大於犧牲層126的寬度。此外,根據本揭露的另一實施例,當阻擋結構104的寬度足夠大時,可將犧牲層126的大部分會被取代為阻擋結構104。堆疊層可包括依序設置於基底102上的基層130、介電層132、底導電層134、壓電層136、頂導電層138和鈍化層140。部分的堆疊層可被設置於空腔120上。空腔120的邊緣120e會鄰近堆疊層,且阻擋結構104可環繞空腔120的邊緣120e。因此,設置在空腔120上的堆疊層可構成膜層106。此外,膜層106可被截斷部112穿透,從而釋放堆疊層中的應力。具體而言,膜層106的基層130可具備所需的彈性(elasticity),因此當聲波或電訊號作用於膜層106時,膜層106可以一定的頻率振動。膜層106的底導電層134和頂導電層138可分別電耦合第一接觸墊114和第二接觸墊116。需注意的是,膜層106的機械行為主要由膜層106的基層130決定,此歸因於設置在基層130上的堆疊層的厚度遠小於基層130的厚度。舉例而言,由介電層132、底部導電層134、壓電層136、頂部導電層138和鈍化層140所組成的堆疊層的整體厚度可能僅為設置於其下的基層130的厚度的1/3到1/10。
FIG. 2 is a schematic cross-sectional view taken along the line AA′ of FIG. 1 according to an embodiment of the present disclosure. Referring to FIG. 2, the blocking
為了使本技術領域中具有通常知識者能夠實現本揭露,下文將進一步描述製作壓電微機械超聲波換能器的方法。此外,由於壓電微機械超聲波換能器可以透過標準的CMOS製程製作,因此在壓電微機械超聲波換能器的同一基底上也可以透過相同的CMOS製程製作相關的電子元件,如場效電晶體、放大器和積體電路。 In order to enable those skilled in the art to realize the present disclosure, the method of manufacturing a piezoelectric micromachined ultrasonic transducer will be further described below. In addition, because piezoelectric micro-machined ultrasonic transducers can be manufactured through standard CMOS processes, related electronic components, such as field-effect devices, can also be manufactured through the same CMOS process on the same substrate of piezoelectric micro-machined ultrasonic transducers. Crystals, amplifiers and integrated circuits.
第3圖是根據本揭露的一實施例所繪示的在基底上形成阻擋結構後
的剖面示意圖。第10圖是示出根據本揭露的一實施例製作壓電微機械超聲波換能器的方法流程圖。參照第3圖,在方法200的步驟202中,提供了基底102,根據不同的要求,可以從半導體基底或絕緣基底中選擇基底102。根據本揭露的一實施例,基底102可以是單晶矽基底。然後,在步驟204中,可從基底102的正面蝕刻,而形成自基底102的頂面102s突出的阻擋結構104。具體而言,在製作阻擋結構104的製程中,可進行光微影和蝕刻製程。由於阻擋結構104的尺寸可以透過微影技術而被精確定義,因此阻擋結構104的兩個相對點之間的距離D亦可以被精確控制。而距離D可用於精確控制阻擋結構104的尺寸和膜層106的尺寸。
FIG. 3 is a diagram illustrating after a barrier structure is formed on a substrate according to an embodiment of the disclosure
Schematic diagram of the cross-section. FIG. 10 is a flowchart showing a method of fabricating a piezoelectric micromachined ultrasonic transducer according to an embodiment of the present disclosure. Referring to FIG. 3, in
第4圖是根據本揭露的一實施例所繪示的在基底上形成犧牲層後的示意圖。參照第4圖,在步驟206中,可以在基底102上形成包括第一部分122和第二部分124的犧牲層,其中阻擋結構104的頂面暴露出於犧牲層。犧牲層的第一部分122可以被阻擋結構104所圍繞,犧牲層的第二部分124可藉由阻擋結構104而與第一部分122分隔。根據本揭露的一實施例,形成犧牲層的製程可包括以下步驟:(1)全面沉積犧牲材料於基底102上(如化學氣相沉積或電漿增強化學氣相沉積),使得犧牲材料覆蓋住阻擋結構104的頂面104s;以及(2)平坦化犧牲材料,直至暴露出阻擋結構104的頂面104s。此外,根據本揭露的另一實施例,形成犧牲層的製程可包括以下步驟:(1)施行旋轉塗布製程,以在基底102上塗布一層犧牲材料;以及(2)蝕刻犧牲材料,直至阻擋結構104的頂面104s被暴露出。因此,透過上述任一形成犧牲層的製程,犧牲層的各分離部分的頂面122s和124s均可切齊阻擋結構104的頂面104s。
FIG. 4 is a schematic diagram after a sacrificial layer is formed on the substrate according to an embodiment of the disclosure. Referring to FIG. 4, in
繼以進行步驟208,在基底102上形成膜層。根據本揭露的一實施例,步驟208可分別包括如第5圖和第6圖所示的子步驟。
Following
第5圖是根據本揭露的一實施例所繪示的在阻擋結構和犧牲層上形成基層後的剖面示意圖。參照第5圖,可以沉積基層130在阻擋結構104上、在犧
牲層的第一部分122上、以及在犧牲層的第二部分124上。基層130可包括具有適當彈性的材料,如結晶矽(c-Si)、非晶矽(a-Si)、富矽氮化物(SiNx)、碳化矽(SiC)等,但不限於此。由於基層130下方的阻擋結構104和犧牲層122、124包括平坦頂面,因此基層130的底面也可以是平坦的底面。此外,為獲得基層130的平坦頂面,可選擇性地進行平坦化製程,以對基層130的頂面進行平坦化。
FIG. 5 is a schematic cross-sectional view after forming a base layer on the barrier structure and the sacrificial layer according to an embodiment of the disclosure. Referring to FIG. 5, a
第6圖是根據本揭露的一實施例所繪示的在基層上形成堆疊層從而形成膜層後的剖面示意圖。參照第6圖,在基底130上可依序沉積介電層132、底導電層134、壓電層136、頂導電層138、鈍化層140,而構成設置於基底102上的膜層150。介電層132可由絕緣材料組成,例如SiO2、SiON、AlN或摻雜鈧的氮化鋁(AlScN),用於將底導電層134和頂導電層138電絕緣於基層130。根據本揭露的一實施例,介電層132也可作為後續沉積在介電層132上的複數層的晶種層。此外,介電層132的表面結構可能會影響沉積在其上的複數層的結晶度。底導電層134和頂導電層138可以是由鉬(Mo)、鈦(Ti)、鋁(Al)或鉑(Pt)所組成的相同或不同的材料,但不限於此。壓電層136可以由氮化鋁(AlN)、摻雜鈧的氮化鋁(AlScN)、鋯鈦酸鉛(PZT)、氧化鋅(ZnO)、聚偏氟乙烯(PVDF)、或鈮酸鉛鈦酸鉛(PMN-PT)所組成,但不限於此。鈍化層140可以是由絕緣材料所構成的選擇性層,如SiO2、SiON或AlN,但不限於此。此外,壓電層136的材料與基層130不同。
FIG. 6 is a schematic cross-sectional view after forming a stacked layer on a base layer to form a film layer according to an embodiment of the disclosure. Referring to FIG. 6, a
第7圖是根據本揭露的一實施例所繪示的形成接觸墊後的剖面示意圖。參照第7圖,多個接觸洞可被形成於膜層150內,以分別暴露出底導電層134和頂導電層138。然後,接觸墊,即第一接觸墊114和第二接觸墊116,可填入至各接觸洞。藉此,第一接觸墊114可電耦合到底導電層134,而第二接觸墊116可電耦合到頂導電層138。
FIG. 7 is a schematic cross-sectional view after forming a contact pad according to an embodiment of the disclosure. Referring to FIG. 7, a plurality of contact holes may be formed in the
第8圖是根據本揭露的一實施例所繪示的在膜層中形成截斷部後的剖面示意圖。參照第8圖,透過去除膜層150的一部分,可形成截斷部112和152。
因此,可以從截斷部112的底部暴露出犧牲層的第一部分122,並且可以從截斷部152的底部暴露出基層130的一部分。根據本揭露的一實施例,雖然第8圖所顯示的截斷部112和152似乎是分開設置的,但當以由上至下的視角觀察第8圖中所示的結構時,截斷部112和152亦可以是呈現連續分布的孔隙,例如環形孔隙。此外,截斷部112和152的俯視形狀不限於第1圖所示的形狀。舉例而言,截斷部112和152可以是部分環繞住膜層106的多邊形孔隙。
FIG. 8 is a schematic cross-sectional view after a cut-off portion is formed in the film according to an embodiment of the disclosure. Referring to FIG. 8, by removing part of the
第9圖是根據本揭露的一實施例所繪示的形成穿透基底的空腔後的剖面示意圖。參照第9圖,在步驟210中,透過蝕刻基底102的背面,可形成穿透基底102的空腔120。因此,犧牲層的第一部分122的底面可以從空腔120暴露出來。空腔120可包括一開口O。空腔120的邊緣120e會鄰近於設置在基底102正面的膜層,且空腔120的邊緣120e可以被用來定義開口O。
FIG. 9 is a schematic cross-sectional view after a cavity penetrating the substrate is formed according to an embodiment of the disclosure. Referring to FIG. 9, in
由開口O所定義的孔徑長度可短於由阻擋結構104的相對點所定義的距離D。由於距離D可用於定義壓電微機械超聲波換能器中的膜層的位置,且距離D主要由阻擋結構104定義,所以即使開口O的位置或尺寸有些許的偏移,也不會導致壓電微機械超聲波換能器的膜層的位置和尺寸有所改變。
The length of the aperture defined by the opening O may be shorter than the distance D defined by the opposing points of the blocking
之後,在步驟212中,可以進行蝕刻過程,以去除暴露出於空腔120的犧牲層的第一部分122。當犧牲層由氧化矽組成時,蝕刻劑可以是氣態氫氟酸(Vapor FH,VHF)。在去除暴露出於空腔120的犧牲層時,由於犧牲層相較於阻擋結構104和基層130的蝕刻選擇比大於10,因此蝕刻劑只能去除犧牲層的第一部分122。另外,由於阻擋結構104會阻止蝕刻劑到達犧牲層的第二部分124,因此在蝕刻過程中,犧牲層的第二部分124不會被蝕除。因此,可以得到如第2圖所示的結構,此結構包括釋放膜層(released membrane)。
Thereafter, in
根據本揭露的上述實施例,由於阻擋結構104是透過蝕刻基底102的正面而形成,因此阻擋結構104可以緊密地附著於基底102,而不會從基底102剝
離,並且可具有垂直側壁。另外,膜層106的尺寸和位置可以被精準定義,而不受到膜層106下方空腔120的尺寸和位置的影響,從而有效地提升了各壓電微機械超聲波換能器100之間的共振頻率均勻性,進而提升了各壓電微機械超聲波換能器的可靠度和電氣性能。
According to the above-mentioned embodiment of the present disclosure, since the
以上所述僅為本發明之較佳實施例,凡依本發明申請專利範圍所做之均等變化與修飾,皆應屬本發明之涵蓋範圍。 The foregoing descriptions are only preferred embodiments of the present invention, and all equivalent changes and modifications made in accordance with the scope of the patent application of the present invention shall fall within the scope of the present invention.
100:壓電微機械超聲波換能器 100: Piezoelectric micromachined ultrasonic transducer
102:基底 102: Base
102s:頂面 102s: top surface
104:阻擋結構 104: blocking structure
106:膜層 106: Membrane
108:主體部分 108: The main part
110:基部 110: base
112:截斷部 112: Truncated part
114:第一接觸墊 114: first contact pad
116:第二接觸墊 116: second contact pad
120:空腔 120: Cavity
120e:邊緣 120e: Edge
126:犧牲層 126: Sacrifice Layer
130:基層 130: grassroots
132:介電層 132: Dielectric layer
134:底導電層 134: bottom conductive layer
136:壓電層 136: Piezo Layer
138:頂導電層 138: Top conductive layer
140:鈍化層 140: passivation layer
Claims (20)
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
TW109122700A TWI747362B (en) | 2020-07-06 | 2020-07-06 | Piezoelectric micromachined ultrasonic transducer and method of fabricating the same |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
TW109122700A TWI747362B (en) | 2020-07-06 | 2020-07-06 | Piezoelectric micromachined ultrasonic transducer and method of fabricating the same |
Publications (2)
Publication Number | Publication Date |
---|---|
TWI747362B true TWI747362B (en) | 2021-11-21 |
TW202203480A TW202203480A (en) | 2022-01-16 |
Family
ID=79907756
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
TW109122700A TWI747362B (en) | 2020-07-06 | 2020-07-06 | Piezoelectric micromachined ultrasonic transducer and method of fabricating the same |
Country Status (1)
Country | Link |
---|---|
TW (1) | TWI747362B (en) |
Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20140214209A1 (en) * | 2011-11-01 | 2014-07-31 | Denso Corporation | Complex device and robot hand drive control apparatus |
US20200194658A1 (en) * | 2017-11-16 | 2020-06-18 | Chirp Microsystems, Inc. | Piezoelectric micromachined ultrasonic transducer with a patterned membrane structure |
-
2020
- 2020-07-06 TW TW109122700A patent/TWI747362B/en active
Patent Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20140214209A1 (en) * | 2011-11-01 | 2014-07-31 | Denso Corporation | Complex device and robot hand drive control apparatus |
US20200194658A1 (en) * | 2017-11-16 | 2020-06-18 | Chirp Microsystems, Inc. | Piezoelectric micromachined ultrasonic transducer with a patterned membrane structure |
Also Published As
Publication number | Publication date |
---|---|
TW202203480A (en) | 2022-01-16 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
EP3233311B1 (en) | Piezoelectric micromachined ultrasonic transducers with low stress sensitivity and methods of fabrication | |
US7667374B2 (en) | Ultrasonic transducer, ultrasonic probe and method for fabricating the same | |
US11844282B2 (en) | Piezoelectric micromachined ultrasonic transducer with a patterned membrane structure | |
US8357981B2 (en) | Transducer devices having different frequencies based on layer thicknesses and method of fabricating the same | |
US9437802B2 (en) | Multi-layered thin film piezoelectric devices and methods of making the same | |
US7770279B2 (en) | Electrostatic membranes for sensors, ultrasonic transducers incorporating such membranes, and manufacturing methods therefor | |
US8526642B2 (en) | Piezoelectric micro speaker including weight attached to vibrating membrane and method of manufacturing the same | |
US8546894B2 (en) | Capacitive micromachined ultrasonic transducer comprising electrode on flexible membrane | |
CN110099344B (en) | MEMS structure | |
TW201921646A (en) | Ultrasonic transducers in complementary metal oxide semiconductor (CMOS) wafers and related apparatus and methods | |
JP2010074143A (en) | Method of fabricating electromechanical device at least including one active element | |
US11631800B2 (en) | Piezoelectric MEMS devices and methods of forming thereof | |
WO2018037730A1 (en) | Capacitive micromachined ultrasonic transducer and ultrasonic imaging apparatus comprising same | |
US11759823B2 (en) | Piezoelectric micromachined ultrasonic transducer and method of fabricating the same | |
US11904356B2 (en) | Ultrasonic transducer, manufacturing method thereof, and ultrasonic imaging device | |
TWI747362B (en) | Piezoelectric micromachined ultrasonic transducer and method of fabricating the same | |
US11498097B2 (en) | Piezoelectric micromachined ultrasonic transducer and method of fabricating the same | |
TWI732688B (en) | Piezoelectric micromachined ultrasonic transducer and method of fabricating the same | |
TWI726800B (en) | Piezoelectric micromachined ultrasonic transducer and method of fabricating the same | |
CN113896165A (en) | Piezoelectric micromechanical ultrasonic transducer and manufacturing method thereof | |
US11890643B2 (en) | Piezoelectric micromachined ultrasonic transducer and method of fabricating the same | |
CN114105082A (en) | Piezoelectric micromechanical ultrasonic transducer and manufacturing method thereof | |
JP2020151796A (en) | Method of manufacturing oscillator substrate and oscillator substrate | |
US20240136994A1 (en) | Micro-electro-mechanical system device and piezoelectric composite stack thereof | |
CN114335320A (en) | Piezoelectric micromechanical ultrasonic transducer and manufacturing method thereof |