591708 玖、發明說明： 【發明所屬之技術領域】 本發明係關於一種應用在濕餘刻梦薄膜之厚度即時 監控裝置與方法。 5 【先前技術】 4政機電糸統（Micro-Electro-Mechanical System，MEMS) 疋目Θ科技界公認最具未來發展潛力及前瞻性的研究領 域’其主要用來製作懸臂樑（Cantilever beam)、薄膜 10 (Diaphragm)、空穴（Cavity)、微流量控制系統（Micr〇_fluidic system)、喷墨印表頭（Ink_jet printing device)等。 啦支機電糸統的製造技術可概分為四類，分別為面型石夕 基加工、體型矽基加工、LIGA技術及各種微機械加工技 術。面型石夕基加工係指利用半導體製程之薄膜沉積及蝕刻 15技術在矽晶圓上製作出微機械元件。體型矽基加工係指利 用非等向性蝕刻、蝕刻終止與蝕刻罩幕等技術蝕刻矽晶圓 本身，製作出微機械元件。UGA技術係結合X-ray光刻術、 電鑄與射出成型製作出高深寬比微機械結構。微機械加工 則利用切削加工、放電加工或射出成型等方法來製作出微 20 機械元件。 製造技術中非等向性蝕刻之蝕刻終止技術，主要分為 下面幾種：P+自動停止蝕刻技術，係以雜質重摻雜入矽晶 圓中（如·硼離子濃度大於l〇19cnr3)，形成一蝕刻阻擋層， 以控制薄膜厚度，但其會造成元件製作之污染與應力之產 6 591708 生且成本較高；電化學自動停止蝕刻，為利用具有η型磊>曰 層之ρ型石夕晶圓形成之ρ_η接合面，施以一反向偏壓進行餘 刻’並控制電壓降使钱刻液僅能餘刻至一特定厚度範圍， 亦有利用類似或其改良之技術，如：光輔助電化學蝕刻停 5 止技術（Photo-Assisted Electrochemical Etch Stop)，係利用 輕摻雜之n型矽晶圓與光強度控制蝕刻率；v形槽深度尺監 控’係先加工{1〇〇}矽晶圓，使其在元件製作區以外之區域 產生一系列寬度不一之V形槽列，其蝕刻深度與開口寬度 具有一固定關係，其後，在濕蝕刻矽晶圓背面時，依照被 10 蝕穿之已知V形槽中所具開口寬度判別矽薄膜之厚度；以 及絕緣層絕緣石夕晶（Silicon on Insulator，SOI)停止#刻技 術，係藉由結構層（device layer)石夕晶圓厚度決定所需石夕薄 膜之厚度（一般為幾微米〜幾十微米），在結構層（device layer)與操控層（handle layer)矽晶圓中夾置一二氧化矽層 15 (Si02)等，藉由蝕刻選擇性使蝕刻液從第二表面操控層矽 晶圓蝕刻至二氧化矽層時即停止。以上之技術主要特徵為 非即時監控濕蝕刻矽薄膜厚度。 目前主要之即時監控濕蝕刻矽薄膜蝕刻停止技術由 Hiroshi Tosaka等人於1995年微機械與微工程期刊（Journal 20 of Micromechanics and Microengineering)第 5期第 41〜46 頁 之’’Optical in situ monitoring of silicon diaphragm thickness during wet etching”所提出之光學停止14刻技術，其在I虫刻 之同時利用矽薄膜與蝕刻液之吸收光波長範圍不同，以干 涉光譜儀偵測矽薄膜之吸收光波長範圍内光強度變化以得 7 知石夕薄膜厚度’此方法之限制為其薄膜必須能夠透光，：故 债測範圍有限僅在2〜20μπχ間。 “本發明主要是提供另一種非光學式即時監控濕钮刻石夕 缚膜之姓刻停止技術’並擴大其_範圍，以利於生產各 種微機電元件所需之矽薄膜厚度。 【發明内容】 本發明之主要目的係在提供—種濕㈣㈣膜厚度 即時監控方法，俾能在濕餘刻進行中，直接量測出微米級 =薄膜厚度’不需將㈣膜移至外界量測，使其利於後 之細作，並在量產中減少成本、增加梦薄膜厚度精 準度。 ，發明之另-目的係在提供_種應用在㈣刻石夕薄 又之即時監控裝置，俾能在濕敍刻時精準量測石夕薄膜 =厚度’且此裝置具财高精準度、架構簡單、 產的特點。 ，達成上述㈣’本發明係有關於—種用在濕钱刻石夕 =度即時監控方法’包含以下步驟：⑷在-Ρ型或η型 腔：：之一第一表面沈積一壓電薄膜材料，並於該壓電薄 狀換成至少一雙痒又指狀換能器；⑻將該雙埠叉指 狀^益與一監控頻率系統相連接，並將相反於該石夕晶圓 之弟-表面且不具該又指狀換能器的—第二表面浸入於一 ^刻液中’使浸潰於該㈣液㈣％晶圓開始進行敍 刻；⑷由該監㈣率錢輸人—„於其卜埠該 5 -u電溥膜材料因壓電效應產生一表面聲波' 该表面聲波並傳遞至另— 該相對應之叉户㈣— 阜域換能器， 0 、此器接收該表面聲波並轉換為電訊號 j至μ控頻率系統，藉由該監控頻率系統得到表面聲 =之一中心頻率響應’則貞知_晶圓上所形成之-石夕薄 =二及⑷當該㈣膜到達所預設之厚度，取出該 石夕日日Β亚結束該濕蝕刻。 10 15 =成上述㈣，本發明係有關於一種應用在濕蝕刻 —屬膜厚度之即時監控裝置，其中該ρ型或η型梦晶圓之 :第=面具有-壓電薄膜材料與至少—雙埠叉指狀換能 二’料度即時監控裝置係包括：一姓刻支揮架，用以支 疋该矽晶圓；—網路分析儀’與該雙埠又指狀換能 用以在濕㈣進行時，同步監測由該叉指狀換能 »輸出之頻率’以及—濕餘刻槽，其與該石夕晶圓 薄膜材料之第二表面相接觸，用以餘刻該石夕晶 β ,其中，當該網路分析儀輸入一電壓於其中一埠該叉指 狀換能器，該壓電薄膜材料會因壓電效應產生一表面聲 ，，該表面聲波會傳遞至另一相對應之一埠該又指狀換能 =，奴指狀換能器會將接收之表面聲波轉換為電訊號輸 出’並精由該網路分析儀得到表面聲波之中心頻率響應， 以即時偵知該矽晶圓上所形成之一矽薄膜之厚度。曰〜 【實施方式】 20 本發明之方法主要為利用表面聲波元件之特性，應用 於濕蝕刻矽薄膜之厚度即時監控裝置，係配合一n型或？型 之矽s曰圓，其正向表面上具有一壓電薄膜材料，在壓電薄 膜材料上又具有至少一雙埠叉指狀換能器，此矽晶圓之米 5勒指標（Miller Indices)晶袼排列方向並無限制，較佳為 {100}或{110}，該矽薄膜厚度即時監控裝置包括一支撐及 固定石夕晶圓之餘刻支撐架、一與雙埠叉指狀換能器相連之 監控頻率系統、以及-與石夕晶圓之一第二表面相接觸之濕 蝕刻槽。其中壓電薄膜材料可包含氧化鋅（ZnO)、氮化鋁 10 (A1N)、鍅鈦酸鉛（PZT)等；而叉指狀換能器較佳是由鋁或 金金屬經由黃光與蝕刻或掀舉（Hft_〇ff)步驟構成，該矽晶 圓之一第二表面較佳為包含一蝕刻罩幕層，以沈積'黃光、 與蝕刻或掀舉（lift-off)技術形成於壓電薄膜材料沈積前， 蝕刻罩幕層較佳為由氮化矽所組成，在氮化矽與矽晶圓間 15更包含一二氧化矽層，以減少氮化矽對矽晶圓之張應力， 蝕刻罩幕層較佳亦可為金金屬，在金金屬與矽晶圓間更包 έ鉻金屬，以增加金金屬層對石夕晶圓之附著性。壓電薄 膜材料較佳為以金屬有機氣相沈積（M〇CVD)、化學氣相沈 積（CVD)、噴灑熱解法（spray pyr〇lysis meth〇d)、溶膠凝膠 2〇 法（sol-gel meth〇d)、直流三極管濺鍍（Dc tri〇de sputtering)、或射頻磁控管錢嫂（RF叫她⑽sp纖加幻 等形成；壓電薄膜材料可直接沉積於矽晶圓上，亦可在壓 電薄膜材料與矽晶圓間因前製程流程加入其他之材料，此 材料依據其與壓電薄膜材料是否能沉積出良好之（〇〇2知軸 591708 方向.，來判別是否於形成壓電薄膜材料前移除，例如^ =幕：會形成於石夕晶圓之第一表面時，壓電薄媒材:可 直接沉積於蚀刻罩幕層上（如壓電薄膜材料氧化辞 =積於高溫爐管熱氧化成長之二氧切上，乃因氧化鋅對 於一乳化石夕、金、銘、翻、石英、氮化石夕、愈石夕之 1:=良好之(叫軸方向），但若此餘刻罩i層不 ίο 圓欲形成壓電薄膜材料之表面之钮刻罩幕層去除；而字= 财系統較佳為—網路分析儀，其中該監控頻率系統^ 15 夕對叉指狀換能器相連，利用監測轉換同時監控多個石夕薄 膑厚度。在濕钮刻液的選擇上，較佳為使 (刪）、四甲基氫氧化録(TMAH)、乙二胺磷苯二紛(卸 氫氧化納、氫氧化鐘、氫氧化鎚、聯氨或氨水等，依 %境及人員安全性與對元件的污染性而做適當之選擇。 在濕I虫刻石夕薄膜完成後，更可包含— 才曰狀換能5，移除叉指狀換能器後更可再包含— 20591708 (1) Description of the invention: [Technical field to which the invention belongs] The present invention relates to a device and method for real-time monitoring of the thickness of a wet wet dream film. 5 [Previous technology] 4 Micro-Electro-Mechanical System (MEMS): Θ is recognized as the most promising future development area and prospective research field in the scientific and technological field. It is mainly used to make cantilever beams, Thin film 10 (Diaphragm), cavity (Cavity), micro flow control system (Micr0_fluidic system), inkjet print head (Ink_jet printing device), and so on. The manufacturing technology of the Lachung Electromechanical System can be roughly divided into four categories, namely surface stone processing, body silicon processing, LIGA technology, and various micro-machining technologies. Surface-type Shixiji processing refers to the fabrication of micromechanical components on silicon wafers using thin film deposition and etching techniques of semiconductor processes. Bulk silicon-based processing refers to the use of anisotropic etching, etching termination, and etching masks to etch the silicon wafer itself to produce micromechanical components. UGA technology combines X-ray lithography, electroforming and injection molding to produce high-aspect-ratio micromechanical structures. Micromachining uses micromachining, electrical discharge machining or injection molding to produce micro-20 mechanical components. The etching termination technology of anisotropic etching in manufacturing technology is mainly divided into the following types: P + automatic stop etching technology, which is heavily doped into silicon wafers with impurities (such as boron ion concentration greater than 1019cnr3), forming An etch stop layer to control the thickness of the film, but it will cause the production of pollution and stress of the component 6 591708 and the cost is high; the electrochemical automatically stops the etching, in order to use the ρ-type stone with η-type epitaxial layer The ρ_η junction surface formed by the wafer is subjected to a reverse bias for the remaining time and the voltage drop is controlled so that the money cutting liquid can only be left to a specific thickness range. There are also similar or improved technologies such as: Photo-Assisted Electrochemical Etch Stop technology uses lightly doped n-type silicon wafers and light intensity to control the etching rate; v-groove depth gauge monitoring is first processed {1〇〇 } Silicon wafer, to produce a series of V-shaped groove arrays with different widths in areas outside the component fabrication area. The etching depth has a fixed relationship with the opening width. Then, when wet etching the back of the silicon wafer, Eroded by 10 The thickness of the silicon thin film is determined by the width of the opening in the known V-shaped groove; and the Silicon On Insulator (SOI) stop #engraving technology is based on the thickness of the silicon layer on the device layer Determine the thickness of the required Shi Xi film (generally several micrometers to several tens of micrometers), sandwich a silicon dioxide layer 15 (Si02), etc. in the silicon layer of the device layer and the handle layer. The etching solution is stopped when the etching solution is etched from the second surface manipulation layer silicon wafer to the silicon dioxide layer by etching. The main feature of the above technology is the non-real-time monitoring of the thickness of the wet-etched silicon film. The current main technology for real-time monitoring of wet-etched silicon film etch stop is Hiroshi Tosaka et al., "Journal of Micromechanics and Microengineering", 1995, Issue 5, pages 41 ~ 46, `` Optical in situ monitoring of "Silicon diaphragm thickness during wet etching" proposed the optical stop 14 etch technique, which uses the difference in the wavelength range of the absorbed light of the silicon film and the etching solution at the same time as the insect etch. The interference spectrometer detects the light in the wavelength range of the absorbed light of the silicon film. The intensity change is 7 to know the thickness of the Shixi film. The limitation of this method is that the film must be able to transmit light. Therefore, the range of debt measurement is limited to only 2 ~ 20μπχ. "The present invention mainly provides another non-optical real-time monitoring of wetness. The name of the engraved stop technology of the button-engraved Shi Xi film is to expand its scope to facilitate the production of silicon film thickness for various micro-electromechanical components. [Summary of the invention] The main purpose of the present invention is to provide a method for real-time monitoring of the wet film thickness, which can directly measure the micron level = film thickness in the wet time, without the need to move the film to the outside. The measurement can make it more conducive to future work, and reduce the cost and increase the precision of the dream film thickness in mass production. The other purpose of the invention is to provide _ a kind of thin and real-time monitoring device applied to engraving Shi Xi, which can accurately measure Shi Xi film = thickness when wet engraving, and this device has high accuracy, structure Simple and productive. In order to achieve the above, the present invention relates to a method for real-time monitoring of engraved stones on wet money, including the following steps: ⑷ depositing a piezoelectric film on a first surface of a -P or n-type cavity: Material, and change at least one pair of itchy and finger-shaped transducers in the piezoelectric thin shape; ⑻ connect the dual-port interdigital finger benefit with a monitoring frequency system, and will be opposite to that of the Shi Xi wafer Brother-the surface without the finger-shaped transducer-the second surface is immersed in a ^ etch solution 'so that the immersion in the ㈣ solution ㈣% wafer begins to be engraved; — “Yu Qibu ’s 5 -u electro-membrane material generates a surface acoustic wave due to the piezoelectric effect ', the surface acoustic wave is transmitted to another — the corresponding fork household ㈣ — Fuyu transducer, 0, this device receives The surface acoustic wave is converted into a signal j to a μ-controlled frequency system, and the surface frequency acoustic = one of the center frequency response is obtained by the monitoring frequency system. Then, the _ is formed on the wafer-Shi Xi thin = 2 and ⑷ When the The diaphragm reaches the preset thickness, and the stone etch is removed to finish the wet etching. 10 15 = Into the above, the hair The Ming Department has an instant monitoring device applied to wet etching—the film thickness, in which the p-type or η-type dream wafer: the first side has-a piezoelectric film material and at least-a dual-port interdigital transducer II 'The real-time monitoring device includes: a surname is engraved to support the silicon wafer;-network analyzer' and the dual-port finger-shaped energy conversion for simultaneous monitoring during wet conditions The interdigital energy conversion »the output frequency 'and-a wet remaining groove, which is in contact with the second surface of the Shi Xi wafer thin film material, to etch the Shi Xi crystal β, wherein when the net The channel analyzer inputs a voltage to one of the interdigital transducers. The piezoelectric film material will generate a surface sound due to the piezoelectric effect, and the surface acoustic wave will be transmitted to another corresponding port. Transducer =, the finger transducer will convert the received surface acoustic wave into electrical signal output 'and the center frequency response of the surface acoustic wave will be obtained by the network analyzer to detect the formation of the silicon wafer in real time The thickness of a silicon film. [Embodiment] 20 The method of the present invention is mainly In order to take advantage of the characteristics of surface acoustic wave elements, it is applied to the wet-etched silicon film thickness real-time monitoring device, which is matched with an n-type or? -Type silicon s-Yuan, which has a piezoelectric film material on the forward surface. There is at least one dual-port interdigital transducer on the material. There is no restriction on the arrangement direction of Miller Indices crystals of this silicon wafer, preferably {100} or {110}. The silicon film The real-time thickness monitoring device includes a support frame for supporting and fixing the Shixi wafer, a monitoring frequency system connected to the dual-port interdigital transducer, and-contacting one of the second surfaces of the Shixi wafer Wet etching tank. The piezoelectric thin film material may include zinc oxide (ZnO), aluminum nitride 10 (A1N), lead hafnium titanate (PZT), etc., and the interdigital transducer is preferably made of aluminum or gold metal via Yellow light and etching or lifting (Hft_00ff) steps, one of the second surface of the silicon wafer preferably includes an etching mask layer to deposit 'yellow light, and etching or lift-off ) Technology is formed before the piezoelectric thin film material is deposited, the etching mask layer is preferably composed of silicon nitride In addition, a silicon dioxide layer is included between the silicon nitride and the silicon wafer 15 to reduce the tensile stress of the silicon nitride on the silicon wafer. The etching mask layer may also be gold metal. Chromium metal is wrapped in between the circles to increase the adhesion of the gold metal layer to the Shixi wafer. The piezoelectric thin film material is preferably metal organic vapor deposition (MOCVD), chemical vapor deposition (CVD), spray pyrolysis method (sol-pyrolysis method), and sol-gel method (sol-gel method). meth〇d), DC triode sputtering, or RF magnetron Qian (RF called her sp fiber plus magic, etc.); piezoelectric thin film materials can be directly deposited on silicon wafers, or The other materials are added between the piezoelectric thin film material and the silicon wafer due to the previous process. This material is based on whether it can be deposited with the piezoelectric thin film material in a good direction (0022 axis 591708 direction) to determine whether it is forming a pressure. Remove the electrical thin film material before, for example, ^ = curtain: when it will be formed on the first surface of Shi Xi wafer, the piezoelectric thin dielectric material can be directly deposited on the etching mask curtain layer (such as the piezoelectric thin film material oxide = product On the two oxygen cuts of the thermal oxidation growth of the high temperature furnace tube, it is because zinc oxide is 1: good for an emulsified stone, gold, Ming, turn, quartz, nitrided stone, and cured stone (called the axis direction), But if the layer i of the mask is not engraved on the surface, the button mask of the surface of the piezoelectric film material is to be formed. The curtain layer is removed; and the word = financial system is better-a network analyzer, in which the monitoring frequency system ^ 15 is connected to the interdigital transducer, and the thickness of multiple thin layers of stone is simultaneously monitored by monitoring conversion. In the selection of the button engraving solution, it is preferable to use (delete), tetramethyl hydroxide (TMAH), ethylenediamine phosphinobenzene (unload sodium hydroxide, bell hydroxide, hammer hydroxide, hydrazine, or ammonia water). According to the environment and personnel safety and the contamination of the components, the appropriate choices are made. After the wet I insect-carved stone film is completed, it can also include — just-shaped energy conversion 5, remove the interdigitated energy conversion. Can be included after the device — 20
薄膜材料；係依此石夕薄膜之功用而定，若為製作 方波感測聲波感測器之壓電薄膜材料的形成可與 明方法之壓電薄膜材料整合為一，以簡化製程步驟。X : 尤又指狀換能器而言，其結構在許多文獻中均 ”、田之5兄明’其主要分為兩種，一為電極條相互交又配 :端由匯流條連在一起，如同二梳子錯差在—起，如圖丨 斤：。另-為一對對電極條相互交叉配置’兩端由 連在-起’如W2所示。在此兩種又指狀換能器中，通常電 11 591708 極條寘度T與電極條間距S均相同，且可產生同相位表面-聲 波為主。前者叉指狀換能器之電極條寬度與電極條間距通 常等於四分之一表面聲波之波長。後者叉指狀換能器之電 極條寬度與電極條間距通常等於八分之一表面聲波之波 5長。又指狀換能器之叉指重疊長度W愈短會造成聲波繞 射，愈長耦合愈強，但會造成諧振峰附近鋸齒狀產生，故 通常設計在30〜100倍波長間。叉指對數N方面，數目越多 幸田射功率愈大，所能接收的信號愈強，但受尺寸的限制， 數目多寡仍有其限制。兩叉指狀換能器之聲波傳遞距離d 10 2為波長的整數倍，但不可太近造成電磁饋通，亦不可太 遠造成傳遞之訊號無法接收。 本發明中較佳為使用如圖2之一對對電極條相互交叉 配置，兩端由匯流條連在一起，且叉指狀換能器之電極條 寬度與電極條間距等於八分之一表面聲波之波長，因輸出 15又^狀換能器之反射波在八分之一表面聲波波長下較四分 之:表面聲波波長下大幅減弱。另外，本發明所設計之表 面聲波之波長（λ)依所需债測之石夕薄膜厚度範圍不同，設計 上可做一適度調整。 20 ㈤壓力感測器與加速度計，微機電元件需要精確厚 2石夕薄膜’故在化學㈣時精確控制㈣膜之厚度對後 -製程非常重要；特別是在微機電聲波感測器中，微米級 :二：膜在製作時’期望能同步的被監測’此乃由於矽薄 正比於頻率響應。本發明之濕㈣㈣膜厚度即時 能在濕_進行中，直接量測出微米級之石夕薄 12 膜厚度’不需將㈣膜移至外界量測，並利於後續製程之 操作在里產中可減少成本、增加石夕薄膜厚度精準度，所 裏作之矽薄膜厚度在微機電元件中可達產品要求。 為能讓貴審查委員能更瞭解本發明之技術内容，特 舉二較佳具體實施例說明如下。 室施例1 本實施例中，利用濕蝕刻矽薄膜厚度即時監控裝置製 作石夕薄膜之流程如圖3所示，在一厚度為296·5_、直^為 10 1〇〇職、綱ρ型矽晶圓110表面以高溫爐管熱氧化：長· 1000Α厚之二氧化矽層120於矽晶圓11〇之兩面，再以低壓 化學氣相沈積儀沉積一 1500人厚之氮化矽層130，後者作為 濕蝕刻時之蝕刻罩幕層，前者為減低矽晶圓丨10與氮化矽層 130之張應力影響，接著以黃光及钱刻或掀舉（1出_〇打)製 15耘在"亥石夕曰曰圓110之第二表面形成一有圖樣之姓刻罩幕 層；在矽晶圓110之第一表面利用射頻磁控管濺鍍一叫❿厚 之氧化鋅層140，其操作條件如表丨所示；此氧化辞層14〇 可直接濺鍍於矽晶圓11〇之第一表面之氮化矽層13〇上如圖 籲 3所示，亦可將氮化矽層13〇去除，濺鍍於二氧化矽層12〇 20上；隨後於氧化鋅層140表面利用電子搶蒸鍍機蒸鍍一 1000Α厚之鋁金屬層150 ,此鋁金屬層uo再以黃光及蝕刻 或掀舉（lift-off)製程產生一輸入叉指狀換能器} 5丨與一輸 出叉指狀換能器152，叉指狀換能器之圖形與特徵如前所詳 述；將此雙埠叉指狀換能器與一 HP8714ES之網路分析儀 25 16〇相連接，並將矽晶圓ι10以一蝕刻支撐架支撐，使矽晶 13 591708 圓up之第二表面浸入一 K〇H之非等向性濕蝕刻液 中’使暴露於_液17()㈣晶圓11G進行非等向性钮刻， 圖斤示此時網路分析儀160輸入一交流電訊號於輸入 叉指狀換能器151，該石夕晶圓11〇上之氧化鋅層14〇會因壓電 效應產生-表面聲波，此表面聲波會傳遞至輸出叉指狀換 能器152’該輸出又指狀換能器152會將接收之表面聲波轉 換為電訊號輸出，藉由網路分析儀⑽得到表面聲波之中心 頻率，得知所形成之矽薄膜之即時厚度 體 沈積壓力（Pa) 射頻功率（W) 濺鍍速率 表1 10Thin film material: It is based on the function of this Shixi film. If the piezoelectric thin film material used to make the square wave sensing acoustic wave sensor is formed, it can be integrated with the piezoelectric thin film material of the method to simplify the process steps. X: Especially for the finger-shaped transducer, its structure is described in many literatures. ”Tian Zhi's 5 brothers' are mainly divided into two types. One is that the electrode strips intersect and mate with each other: the ends are connected by the bus bar. As if the two combs are in the wrong position, as shown in Figure 丨: Another-a pair of opposite electrode strips are arranged to cross each other. In the transducer, usually the pole position T and electrode strip pitch S are the same, and can produce the same phase surface-acoustic wave. The width of the electrode strip and the strip pitch of the interdigital transducer are usually equal to four points. One of the wavelengths of surface acoustic waves. The width of the electrode strips and the distance between the electrode strips of the interdigital transducer are usually equal to one-eighth of the length of the surface acoustic wave. The shorter the interdigit overlapping length W of the interdigital transducer, the shorter Causes the diffraction of acoustic waves. The longer the coupling is, the stronger the coupling will be. However, it will cause a zigzag around the resonance peak, so it is usually designed between 30 and 100 times the wavelength. In terms of the number of interdigits, the more the number, the better the radiation power. The stronger the signal, but limited by size, the number still has its limit. The acoustic wave transmission distance d 10 2 of the finger transducer is an integer multiple of the wavelength, but it should not be too close to cause electromagnetic feedthrough or too far to cause the transmitted signal to be unreceivable. It is preferred to use one of the two methods in the present invention. The opposite electrode strips are arranged to cross each other, and the two ends are connected by a bus bar, and the width of the electrode strips and the distance between the electrode strips of the interdigital transducer are equal to one-eighth of the surface acoustic wave wavelength. The reflected wave of the device is lower than one-eighth of the surface acoustic wave wavelength: the surface acoustic wave wavelength is greatly reduced. In addition, the wavelength (λ) of the surface acoustic wave designed by the present invention is based on the thickness range of the Shixi film measured according to the required debt Different, a moderate adjustment can be made in the design. 20 ㈤ pressure sensor and accelerometer, micro-electromechanical components need to be precisely 2 shi Xi film 'so precise control of the thickness of the ㈣ film during chemical ㈣ is very important for the post-process; especially It is in the micro-electromechanical acoustic wave sensor, micron level: two: the film is 'desirably synchronized to be monitored' when it is made. This is because the silicon thin film is proportional to the frequency response. The wet film thickness of the present invention can be performed immediately in wet conditions. , Directly measure the micron-scale Shi Xi thin 12 film thickness' without the need to move the diaphragm to the outside measurement, and facilitate the subsequent process operations in the production can reduce costs, increase the accuracy of Shi Xi film thickness, The thickness of the silicon thin film can meet the product requirements in micro-electromechanical components. In order to allow your reviewers to better understand the technical content of the present invention, two preferred specific embodiments are described below. Room Example 1 In this embodiment, the use of The process of making Shixi film by the wet etching silicon film thickness real-time monitoring device is shown in Fig. 3. The surface of a silicon wafer 110 with a thickness of 296 · 5 mm and a thickness of 10 100 mm is heated by a high temperature furnace tube. Oxidation: Long · 1000A thick silicon dioxide layer 120 on both sides of silicon wafer 110, and then a 1500-person thick silicon nitride layer 130 was deposited by a low-pressure chemical vapor deposition apparatus, which was used as an etching mask during wet etching. Layer, the former is to reduce the effect of the tensile stress of the silicon wafer 丨 10 and the silicon nitride layer 130, and then carved or lifted (1 out _ 0 dozen) with yellow light and money (15 out of _ 0 dozen) made in "quotation" A patterned engraved mask layer is formed on the second surface of 110; The first surface of the circle 110 is sputter-coated with a thick zinc oxide layer 140 using a radio frequency magnetron. The operating conditions are shown in Table 丨; this oxide layer 14 can be directly sputtered on the silicon wafer 11 The silicon nitride layer 13 on one surface is as shown in FIG. 3, and the silicon nitride layer 13 can also be removed and sputtered on the silicon dioxide layer 1220; then, the surface of the zinc oxide layer 140 can be grabbed by electrons. The vapor deposition machine vaporizes a 1000A thick aluminum metal layer 150, and the aluminum metal layer uo then uses an yellow light and an etching or lift-off process to generate an input interdigital transducer} 5 丨 and an output fork Finger transducer 152, the interdigitated transducer's graphics and features are as detailed above; this dual-port interdigital transducer is connected to a HP8714ES network analyzer 25 160, and the silicon Wafer ι10 is supported by an etch support, so that the second surface of the silicon crystal 13 591708 circle up is immersed in a KOH non-isotropic wet etching solution, so that it is exposed to _Liquid 17 () ㈣ Wafer 11G for non- Isotropic button engraving, the picture shows that at this time the network analyzer 160 inputs an AC signal to the interdigital transducer 151, and the zinc oxide on the Shixi wafer 11 14〇 will be generated by the piezoelectric effect-surface acoustic wave, this surface acoustic wave will be transmitted to the output interdigital transducer 152 ', which in turn will convert the received surface acoustic wave into an electrical signal output. The network analyzer⑽ obtains the center frequency of the surface acoustic wave, and knows the instant thickness thickness deposition pressure (Pa) of the formed silicon film RF power (W) Sputtering rate Table 1 10
ZnO直徑4时 Ar/〇2 8x10-5 200" 20〇· 503〇X^hT IT 其:，在網路分析儀_面，由於Μ膜在液體中膜 :時 關係’如圖6所示’故在膜厚小於表面聲波之波 =，可利用頻率推知膜厚，而在膜厚大於表面聲波之波 …隹Ιί 此乃由於所產生之表面聲波， ，集中於一個表面聲波波長之薄臈表面厚度，對於較 性；但當膜厚小於_個表面對頻率不具影響 變小而呈線性迅速變小㈣’頻㈣著膜厚 在頻率與插入損失關係圖中，當 14 15 591708 定義最低插入損失值所對應之頻率為中心頻率，則在不-同 石夕薄膜厚度下，可以理論得知其與中心頻率之關係；在濕 #刻進行日^，對應此關係圖，即可得知矽薄膜之即時厚度。 當石夕晶圓未開始進行似彳前，網路分析儀16吐會顯示出頻 5率與插入損失關係圖，如圖7a所示，此時矽晶圓厚度]^為 296·5μηι，中心頻率17為58 〇1]^112，當矽晶圓厚度H漸漸被 ΚΟΗ濕餘刻變薄至9〇·87μηι時，中心頻率？仍為58 〇iMHz 與矽晶圓未蝕刻前之中心頻率相同，此現象乃因表面聲波無 法傳遞至矽薄膜底部，故雖厚度改變卻無法顯示於頻率改 10變上，如圖7b所示，繼續濕蝕刻矽晶圓，當矽晶圓厚度11 漸漸變薄至64·78μηι小於表面聲波之波長時，中心頻率1?變 為57·5ΜΗζ，如圖7c所示，當矽晶圓厚度Η到達預期厚度 55_894111時，中心頻率17會漂移至目標值56.4]^112，如圖7(1 所示。 15 在本實施例中，所使用之叉指狀換能器為一對對電極 條相互父叉配置，兩端由匯流條連在一起，如圖2所示，其 中參數尺寸如表2所示： 叉指狀換能器 ί數尺寸 ' 叉指狀換能器之波長（λ) 80μηι 叉指重疊長度（W)~ 3040μηι 叉指長度（L) 3360μιη 聲波傳遞路徑之長度（d) 1520μιη 叉指對數（N) 95 --- 銲墊面積 65μιη χ65μιη 15 表2 - 本貫施例中，可· p 士 1〜80哗之間。 卩之梦薄膜厚度範圍約介於 5 實施例2 程如iL用所餘1石夕薄膜厚度即時監控装置製作石夕薄膜之流 矛王如圖4所不，在一艮声勹ZnO diameter 4 when Ar / 〇2 8x10-5 200 " 20〇 · 503〇X ^ hT IT It: On the network analyzer surface, since the M film is in the liquid film: time relationship 'as shown in Figure 6' Therefore, when the film thickness is smaller than the surface acoustic wave =, the frequency can be used to infer the film thickness, and the film thickness is larger than the surface acoustic wave ... 隹 Ιί This is because the surface acoustic wave generated is concentrated on a thin surface with a surface acoustic wave wavelength Thickness, for comparison; but when the film thickness is less than _ the surface has no effect on the frequency, it becomes linear and rapidly decreases. The frequency of the film thickness in the relationship diagram of frequency and insertion loss, when 14 15 591708 defines the minimum insertion loss The frequency corresponding to the value is the center frequency. Under different film thicknesses, the relationship between the center frequency and the center frequency can be known theoretically. The day is performed in the wet # 刻, corresponding to this relationship diagram, the silicon film can be obtained. The instant thickness. When the Shi Xi wafer does not start to appear to be 彳 like, the network analyzer 16 will display the relationship between frequency 5 and insertion loss, as shown in Figure 7a, at this time the thickness of the silicon wafer] ^ is 296 · 5μηι, the center The frequency 17 is 58 〇1] ^ 112. When the thickness H of the silicon wafer is gradually thinned to 90 · 87μη by the wetness, the center frequency? It is still the same as the center frequency before the silicon wafer is not etched. This phenomenon is because the surface acoustic wave cannot be transmitted to the bottom of the silicon film, so the thickness cannot be displayed on the frequency change 10, as shown in Figure 7b. Continue to wet-etch the silicon wafer. When the thickness of the silicon wafer 11 gradually becomes thinner to 64 · 78μηι, which is smaller than the wavelength of the surface acoustic wave, the center frequency 1? Becomes 57.5MΗζ, as shown in Figure 7c. When the thickness is expected to be 55_894111, the center frequency 17 will drift to the target value of 56.4] ^ 112, as shown in Figure 7 (1. 15 In this embodiment, the interdigitated transducer used is a pair of opposite electrode strips and a parent of each other Fork configuration, the two ends are connected by bus bars, as shown in Figure 2, where the parameter dimensions are shown in Table 2: Interdigitated transducer's number of dimensions' Wavelength (λ) of interdigital transducer 80μηι Fork Finger overlap length (W) ~ 3040μηι Interdigitated finger length (L) 3360μιη Acoustic wave transmission path length (d) 1520μιη Interdigitated logarithm (N) 95 --- Pad area 65μιη χ65μιη 15 Table 2-In this example, · P ± 1 to 80. The thickness range of 卩 之 梦 film Example 5 2 between drive iL As with the remainder of 4 is not a real-time monitoring of film thickness stone Xi Shi Tokyo film production apparatus ilk spear FIG Wang, Bao sound in a Gen
型石夕晶圓210之第一 Γ ㈣ 為1〇〇mm、il〇〇}P 一表面熱蒸鍍一層100A厚之鉻金屬層 220’再熱蒸鑛一層9〇〇a尸 a 10 # 金屬層230，後者作為濕蝕 ^ ^ 層，前者為增加矽晶圓210與金金屬層23〇 之黏者力，接著以黃光及餘刻或掀舉⑽卜〇ff)製程，在該 梦曰曰圓21G之第二表面形成—有圖樣之钱刻罩幕層，·在石夕晶 圓210之第一表面利用射頻磁㈣㈣—_厚之氧㈣ 15 層240 ;隨後於氧化鋅層24〇表面利用電子槍蒸鍍機蒸鍍一 ιοοοΑ厚之鋁金屬層25〇，此鋁金屬層25〇再以黃光及蝕刻 或掀舉（lift-off)製程產生一輸入叉指狀換能器251與一輸 出又指狀換能器252,又指狀換能器之圖形與特徵如前所詳 述；將此雙埠叉指狀換能器與— HP8714ES之網路分析儀 160相連接，並將矽晶圓以一蝕刻支擇架支撐，使矽晶圓之 20第二表面浸入一 K0H之非等向性濕蝕刻液17〇中，使暴露 於餘刻液1 70的矽晶圓進行非等向性蝕刻，如圖5所示；此 時網路分析儀160輸入一交流電訊號於輸入叉指狀換能器 251 ’該矽晶圓21〇上之氧化辞層240會因壓電效應產生一表 面聲波’此表面聲波會傳遞至輸出叉指狀換能器252,該輪 25出又指狀換能器252會將接收之表面聲波轉換為電訊號輸 16 591708 出，藉由網路分析儀16〇得到表面聲波之中心頻 濕蝕刻形成之矽薄膜之即時厚度。 ψ 條相=實施例中，所使用之叉指狀換能器為—對對電極 八〜又、配置，兩端由匯流條連在一起，如圖2所 與實施例1中相同。 ’、一 上述實施例僅係為了方便說明而舉例而已 主張之權利範圍自應以申請專利範圍所述為準 於上述實施例。 L圃式簡單說明】 圖1係本發明一較佳實施例之叉指狀換能器正視圖。 圖2係本發明另—較佳實施例之叉指狀換能器正視圖。 圖3係本發明—較佳實施例之製作㈣膜流程圖。 15 本發明所 而非僅限The first Γ ㈣ of the type Shixi wafer 210 is 100mm, il0〇P. One surface is thermally vapor-deposited with a 100A-thick chrome metal layer 220 ′, and the thermally-deposited layer is 900-a-a 10 # metal. Layer 230, the latter as a wet etched layer, the former is to increase the adhesion between the silicon wafer 210 and the gold metal layer 23, and then the process of yellow light and the moment or lift (⑽ff) is used in the dream The second surface of the circle 21G is formed with a patterned engraved mask layer. · On the first surface of the Shixi wafer 210, a radio frequency magnetic field is used—_thick oxygen field 15 layer 240; then on the zinc oxide layer 24. A thick aluminum metal layer 25 was deposited on the surface by an electron gun vapor deposition machine, and the aluminum metal layer 25 was then processed by yellow light and etching or lift-off to generate an input interdigital transducer 251 and The output and finger transducers 252, and the figures and features of the finger transducers are as detailed above; connect this dual-port interdigital transducer to the HP8714ES network analyzer 160, and The silicon wafer is supported by an etching support, so that the second surface of the silicon wafer 20 is immersed in a KOH non-isotropic wet etching solution 17 and exposed to the etching solution 17 0 silicon wafer is anisotropically etched, as shown in FIG. 5; at this time, the network analyzer 160 inputs an AC signal to the input interdigital transducer 251 'the oxide layer on the silicon wafer 21 240 will generate a surface acoustic wave due to the piezoelectric effect. This surface acoustic wave will be transmitted to the output interdigital transducer 252. The wheel 25 out and the finger transducer 252 will convert the received surface acoustic wave into an electrical signal. 16 591708 The instantaneous thickness of the silicon film formed by the center frequency wet etching of the surface acoustic wave was obtained by the network analyzer 160. ψ phase = In the embodiment, the interdigital transducer used is-the counter electrode VIII ~, and is configured, and the two ends are connected by a bus bar, as shown in Fig. 2 which is the same as that in the embodiment 1. 'The above-mentioned embodiments are merely examples for convenience of explanation and the scope of rights claimed should be based on the scope of the patent application as the above-mentioned embodiments. Brief description of the L-type] Fig. 1 is a front view of a cross-finger transducer according to a preferred embodiment of the present invention. FIG. 2 is a front view of an interdigital transducer according to another preferred embodiment of the present invention. FIG. 3 is a flowchart of manufacturing a diaphragm according to the present invention—a preferred embodiment. 15 The invention is not limited to
圖4係本發明另—較佳實施例之製作⑪薄膜流程圖。 圖^系本發明—較佳實施例之濕㈣㈣膜之厚度即日; 控虞置不意圖。 20 圖6係本發明一較佳實施例之矽薄膜在液體 頻率之關係圖。 中膜厚對中心FIG. 4 is a flow chart of fabricating a rhenium film according to another preferred embodiment of the present invention. Figure ^ is the thickness of the wet film of the present invention-the preferred embodiment; 20 FIG. 6 is a relationship diagram of a silicon thin film at a liquid frequency according to a preferred embodiment of the present invention. Center thickness
圖7a-7d係本發明一較佳實施例之網路分析儀 頻率與插入損失關係圖。 上所顯不之 12〇二氧化矽層130氮化矽層 【圖號說明】 110矽晶圓 17 591708 140 152 210 240 252 15 1輸入叉指化換 能器 170濕蝕刻液 230金金屬層 251輸入叉指狀換 能器 _氧化鋅層 150鋁金屬層 輸出叉指狀換160網路分析儀 能器 矽晶圓 220鉻金屬層 氧化鋅層 250鋁金屬層 輸出叉指狀換 能器 鲁Figures 7a-7d are diagrams of the relationship between frequency and insertion loss of a network analyzer according to a preferred embodiment of the present invention. Shown on the top 12 silicon dioxide layer 130 silicon nitride layer [illustration of the number] 110 silicon wafer 17 591708 140 152 210 240 252 15 1 input interdigital transducer 170 wet etching solution 230 gold metal layer 251 Input interdigital transducer _ zinc oxide layer 150 aluminum metal layer output interdigital transducer 160 network analyzer function silicon wafer 220 chromium metal layer zinc oxide layer 250 aluminum metal layer output interdigital transducer Lu
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