1334271 • , 九、發明說明： 【發明所屬之技術領域】 本發明係有關於一種薄膜體聲波共振器之製造方 • &，特別係有關☆-種可提高感測度《薄膜體聲波共振器 之製造方法。 【先前技術】1334271 • , IX. Description of the Invention: [Technical Field of the Invention] The present invention relates to a method for manufacturing a film bulk acoustic resonator, and particularly relates to a ☆-type improved sensitivity "film bulk acoustic resonator" Production method. [Prior Art]
Ik著半導體製程技術的進步，習知使用於生物醫學、 汽車工業、精緻農業及機械工藝等之感測器元件已由表面 # 聲波（SurfaCe WaVe Acoustic, SAW)共振器提昇至薄膜體聲 波（Film Bulk Acoustic Resonat〇r，FBAR)共振器，如第 i 圖所示，習知薄膜體聲波共振器1〇〇係包含有一矽基板 110、一第一保護層120、一第二保護層13〇、一第一電極 層140、一壓電層150及一第二電極層16〇，該矽基板11〇 係具有一第一表面11卜一第二表面112與一共振腔113, 該共振腔113係貫穿該第一表面ιη與該第二表面112, φ 該第一保護層1 20係形成於該第一表面111，該第二保護 層130係形成於該第二表面112，其中該共振腔113係顯 露出該第一保護層120，該第一電極層14〇係形成於該第 一保護層120上方，該壓電層15〇係形成於該第一保護層 120上方並覆蓋該第一電極層14〇，該第二電極層丨6〇係 形成於該壓電層150之一第三表面151，由於習知薄膜題 聲波共振器100之該第一電極層14〇係被該第一保護層 120所覆蓋，因此感測靈敏度較差。 【發明内容】 1334271 本發明之主要目的係在於提供一種薄膜體聲波共振 器之製造方法’首先’提供一石夕基板，該石夕基板係具有一 第一表面與一第二表面’該第一表面係形成有一保護層； 接著，形成一第一電極層於該保護層上；之後，蝕刻該矽 基板之該第二表面以形成一共振腔；接著，形成一壓電層 於該保護層上’並且該壓電層係覆蓋該第一電極層；之 後，形成一第二電極層於該壓電層上；最後，經由該共振 腔蝕刻該保護層以顯露出該第一電極層。由於本發明之該 共振腔係顯露出該第一電極層，因此可提高該薄膜體聲波 共振器之感測靈敏度。 【實施方式】 請參閱第2A至2H圖’依據本發明之一具體實施例係 揭示一種薄膜體聲波共振器200之製造方法，首先，請參 閱第2A圖，提供一石夕基板210，該石夕基板210係具有一 第一表面211與一第二表面212,較佳地，該矽基板210 係預先經過一清洗處理步驟，該第一表面211係形成有一 保護層220,該第二表面212係形成有一蝕刻遮罩層230， 在本實施例中，該保護層220與該蝕刻遮罩層230之形成 方法係可為低壓化學氣相沉積（Low Pressure Chemical Vapor Deposition，LPCVD)法，該保護層220與該蝕刻遮 罩層230之材質係可為氮化矽（SiNx);接著，請參閱第 2B圖，圖案化該蝕刻遮罩層230並顯露出該矽基板21〇 之該第二表面212’在本實施例中’圖案化該银刻遮罩層 230之方法係採用乾式钱刻法中之反應性離子姓刻製程； 1334271 接著參閱第2C圖，形成_第__電極層24()於該第一 保護層22G上，該第—電極層24。之材質係可選自於紹、 金、鉬或鉑等金屬材料，在本實施例中，該第一電極層24〇 之材質係可為鉑，該第一電極層24〇之形成方法係為直流 賤鍍法（DC sputter);之後，請參閱第犯圖，以該圖案 匕之姓刻遮罩層230為遮罩，蝕刻該矽基板21〇之該第二 表面212以形成一共振腔213，在本實施例中，該共振腔 213並未貫穿該矽基板210之該第一表面2n，該共振腔 213係具有一底部213ae或者，請參閱第3圖在另一實 施例中，以該圖案化之蝕刻遮罩層23〇為遮罩，蝕刻該矽 基板210之該第二表面212以形成該共振腔213之步驟 中’該共振腔213係貫穿該矽基板21〇之該第一表面211 與該第二表面212,該共振腔213係顯露出該保護層22〇， 其中蝕刻該矽基板210之該第二表面212之方法係為濕式 姓刻法’蝕刻該矽基板210之該第二表面212之蝕刻液係 為氫氧化鉀（KOH )，此外，蚀刻液亦可為氫氧化鉀與丙 嗣之混合液。 接著’請參閱第2E圖，形成一壓電層250於該第一 保護層220上，並且該壓電層250係覆蓋該第一電極層 240 ’該壓電層250之材質係可選自於氮化鋁、氧化鋅或 硫化哂等，在本實施例中，該壓電層250之材質係為氧化 辞’其中該壓電層250之形成方法係為射頻濺鍍法（rf sputter);之後，請參閱第2F圖，蝕刻該壓電層25〇以形 成一腔室251，在本實施例中，蝕刻該壓電層25〇以形成 1334271 該腔至25 1之蝕刻液係為硝酸（HN〇3 );接著請參閱第 2G圖，形成一第二電極層26〇於該壓電層25〇上且該 第二電極層260係顯露出該腔室251，該第二電極層26〇 之材質係可選自於鋁、金、鉬或鉑等金屬材料，在本實施 例中，該第一電極層240之材質係為鉬，該第二電極層26〇 之形成方法係為直流濺鍍法（DCsputter);最後，請參閱 第2H圖，經由該共振腔213蝕刻該保護層22〇以顯露出 該第一電極層240，以形成一種薄膜體聲波共振器2〇〇， 在本實施例中，係先蝕刻該共振腔213之該底部2Ua，以 顯露出該保護層220，接著再經由該共振腔213蝕刻該保 濩層220以顯露出該第一電極層24〇，蝕刻該底部213&與 該保護層220之方法係為乾式蝕刻法，其中蝕刻該底部 2 13a與該保護層220之方法係可選自於反應性離子蝕刻製 程 '感應叙合電漿姓刻製程、高功率雷射削薄製程或聚焦 離子束削薄製程’在本實施例中，該第一電極層240係具 有一第一側壁241與一第二側壁242，該保護層22〇係具 有一第三側壁221 ’該壓電層250之該腔室251係鄰近該 第一側壁241 ’該保護層22〇之該第三側壁221係平齊該 第一電極層240之該第二側壁242，或者，請參閱第3及 4圖所示’在另一實施例中，由於該共振腔213係已顯露 出該保護層220，因此可直接經由該共振腔213姓刻該保 護層220以顯露出該第一電極層240。此外，本發明係可 另包含一移除該蝕刻遮罩層23 0之步驟，以顯露出該矽基 板210之該第二表面212。 /1 接著，對該薄膜體聲波共振器200進行微小 :，其係先利用直流藏鑛法於該石夕基板210 面 212、該共振腔⑴及該共振腔213顯露之該第 面 ;:錄上厚度分別為―一 8nm之鈦金屬= 旦以網路分析儀對該薄膜體聲波共振器200進行頻率響 ‘、、里Μ纟量測結果如第5圖所示，圖中顯示鈦金屬之厚 度越厚(質量負載越大)’其元件共振頻率越往低頻移動， 又’請參㈣6圖，其係為質量負載對共振頻率改變量影 響之關係圖，圖中橫轴係表示質量增加量⑽），縱轴係 表示頻率變化量⑷），而Μ與“兩者之比值（川5m) ^為圖=虛線之斜率，將第6圖所得之結㈣人感測度計 式 Sm = Um<S —f/<5 m)可求得感測度為 3654 HZCm2/nge 發月之保護範圍當視後附之申請專利範圍所界定 ^為準’任何熟知此項技藝者，在不脫離本發明之精神和 範圍内所作之任何變化與修改，均屬於本發明之保護範 圍。 【圖式簡單說明】 第 1 圖：習知薄膜體聲波共振器之截面示意圖。 第2A至2H圖：依據本發明之一具體實施例，一種薄膜體 聲波共振器之製造方法之截面示意圖。 圖：依據本發明之另一具體實施例，另一種薄 膜體聲波共振器之製造方法中一共振腔 係貫穿矽基板之第一表面之截面示意圖。 第 4 圖：依據本發明之另一具體實施例，該薄膜體 1334271 聲波共振器之截面示意圖。 第 5 圖：依據本發明之一具體實施例，該薄膜體聲 波共振器鍍上各種厚度之鈦金屬後所測 得之頻率響應圖。 第 6 圖：依據本發明之一具體實施例，該薄膜體聲 波共振器之質量負載對共振頻率改變量 影響之關係圖。 【主要元件符號說明】 100 薄膜體聲波共振器 110 矽基板 111 第一表面 112 第二表面 113 共振腔 120 保護層 130 姓刻遮罩層 140 第一電極層 150 壓電層 151 第三表面 160 第二電極層 200 薄膜體聲波共振器 210 矽基板 211 第一表面 212 第二表面 213 共振腔 213a 底部 220 保護層 221 第三側壁 230 蚀刻遮罩層 240 第一電極層 241 第一側壁 242 第二側壁 250 壓電層 251 腔室 260 第二電極層Ik is advancing with semiconductor process technology. It is known that sensor components used in biomedicine, automotive industry, fine agricultural and mechanical processes have been enhanced by surface acoustic waves (SurfaCe WaVe Acoustic, SAW) resonators to film bulk acoustic waves (Film Bulk Acoustic Resonat〇r, FBAR) resonator, as shown in FIG. 1, the conventional film bulk acoustic resonator 1 includes a substrate 110, a first protective layer 120, and a second protective layer 13 a first electrode layer 140, a piezoelectric layer 150 and a second electrode layer 16A, the 矽 substrate 11 has a first surface 11 and a second surface 112 and a resonant cavity 113, the resonant cavity 113 The first protective layer 120 is formed on the first surface 111, and the second protective layer 130 is formed on the second surface 112. The resonant cavity 113 is formed through the first surface ι and the second surface 112. The first protective layer 120 is formed on the first protective layer 120. The piezoelectric layer 15 is formed on the first protective layer 120 and covers the first electrode. a layer 14〇, the second electrode layer 丨6 is formed in the One surface 151 of the third dielectric layer 150, since the first electrode layer 14〇 conventional film-based problem of acoustic resonator 100 is 120 to cover the first protective layer, the sensing sensitivity is poor sensing. SUMMARY OF THE INVENTION The main object of the present invention is to provide a method for fabricating a film bulk acoustic resonator, which first provides a slab substrate having a first surface and a second surface 'the first surface Forming a protective layer; then, forming a first electrode layer on the protective layer; thereafter, etching the second surface of the germanium substrate to form a resonant cavity; and then forming a piezoelectric layer on the protective layer And the piezoelectric layer covers the first electrode layer; then, a second electrode layer is formed on the piezoelectric layer; finally, the protective layer is etched through the resonant cavity to expose the first electrode layer. Since the resonant cavity of the present invention reveals the first electrode layer, the sensing sensitivity of the film bulk acoustic resonator can be improved. [Embodiment] Please refer to FIGS. 2A to 2H. In accordance with an embodiment of the present invention, a method for manufacturing a film bulk acoustic resonator 200 is disclosed. First, please refer to FIG. 2A to provide a Shishi substrate 210. The substrate 210 has a first surface 211 and a second surface 212. Preferably, the substrate 210 is subjected to a cleaning process. The first surface 211 is formed with a protective layer 220. The second surface 212 is formed. An etch mask layer 230 is formed. In this embodiment, the protective layer 220 and the etch mask layer 230 are formed by a Low Pressure Chemical Vapor Deposition (LPCVD) method. The material of the etch mask layer 230 may be tantalum nitride (SiNx); then, referring to FIG. 2B, the etch mask layer 230 is patterned and the second surface 212 of the germanium substrate 21 is exposed. In the present embodiment, the method of patterning the silver engraved mask layer 230 is performed by a reactive ion etch process in a dry-cut method; 1334271 and then referring to FIG. 2C, forming a ____ electrode layer 24 () On the first protective layer 22G, - of electrode layer 24. The material of the first electrode layer 24 can be made of platinum, and the first electrode layer 24 is formed by using a metal material such as sho, gold, molybdenum or platinum. DC sputter; afterwards, please refer to the first map, the mask layer 230 is masked by the pattern, and the second surface 212 of the germanium substrate 21 is etched to form a resonant cavity 213. In this embodiment, the resonant cavity 213 does not extend through the first surface 2n of the cymbal substrate 210. The resonant cavity 213 has a bottom 213ae or, please refer to FIG. 3 in another embodiment, The patterned etch mask layer 23 is a mask, and the second surface 212 of the germanium substrate 210 is etched to form the resonant cavity 213. The resonant cavity 213 extends through the first surface of the germanium substrate 21 211 and the second surface 212, the resonant cavity 213 reveals the protective layer 22, wherein the method of etching the second surface 212 of the germanium substrate 210 is wet-etched to etch the germanium substrate 210 The etching liquid of the second surface 212 is potassium hydroxide (KOH), and the etching liquid may also be hydrogen hydroxide. A mixture of potassium and propylene. Then, referring to FIG. 2E, a piezoelectric layer 250 is formed on the first protective layer 220, and the piezoelectric layer 250 covers the first electrode layer 240. The material of the piezoelectric layer 250 can be selected from In the present embodiment, the piezoelectric layer 250 is made of an oxidized word, wherein the piezoelectric layer 250 is formed by a radio frequency sputtering method (rf sputter); Referring to FIG. 2F, the piezoelectric layer 25 is etched to form a chamber 251. In this embodiment, the piezoelectric layer 25 is etched to form 1,332,271. The chamber is etched to a volume of nitric acid (HN). 〇3); then, referring to FIG. 2G, a second electrode layer 26 is formed on the piezoelectric layer 25A and the second electrode layer 260 is exposed to the chamber 251. The second electrode layer 26 is formed. The material may be selected from a metal material such as aluminum, gold, molybdenum or platinum. In this embodiment, the material of the first electrode layer 240 is molybdenum, and the second electrode layer 26 is formed by direct current sputtering. Finally, please refer to FIG. 2H, and the protective layer 22 is etched through the resonant cavity 213 to expose the first electrode. 240, to form a film bulk acoustic resonator 2 〇〇, in this embodiment, the bottom portion 2Ua of the resonant cavity 213 is first etched to expose the protective layer 220, and then etched through the resonant cavity 213 The layer 220 is formed to expose the first electrode layer 24, and the method of etching the bottom portion 213 & and the protective layer 220 is a dry etching method, wherein the method of etching the bottom portion 23a and the protective layer 220 is selected from In the present embodiment, the first electrode layer 240 has a first sidewall 241 and a reactive ion etching process, an inductively spliced plasma process, a high-power laser thinning process, or a focused ion beam thinning process. a second sidewall 242, the protective layer 22 has a third sidewall 221'. The chamber 251 of the piezoelectric layer 250 is adjacent to the first sidewall 241. The third sidewall 221 of the protective layer 22 is flat. The second sidewall 242 of the first electrode layer 240 is aligned, or please refer to FIGS. 3 and 4. In another embodiment, since the resonant cavity 213 has exposed the protective layer 220, it can be directly The protective layer 220 is pasted through the resonant cavity 213 to reveal The first electrode layer 240. Furthermore, the present invention may further comprise the step of removing the etch mask layer 230 to expose the second surface 212 of the ruthenium substrate 210. /1, the film bulk acoustic resonator 200 is microscopically: firstly, the first surface exposed by the DC substrate 210, the resonant cavity (1) and the resonant cavity 213 by using a DC deposit method; Titanium metal with an upper thickness of -8 nm = the frequency of the film bulk acoustic resonator 200 is measured by a network analyzer, and the measurement results of the inner diameter are shown in Fig. 5, and the titanium metal is shown in the figure. The thicker the thickness (the greater the mass load), the more the element's resonant frequency moves toward the lower frequency, and the '4' is the relationship between the mass load and the amount of change in the resonant frequency. The horizontal axis indicates the mass increase. (10)), the vertical axis represents the frequency change (4)), and the ratio of Μ to "the ratio of the two (chuan 5m) ^ is the slope of the graph = dashed line, and the knot obtained in Fig. 6 (4) human sensibility meter Sm = Um<S-f/<5 m) can be obtained with a sensitivity of 3654 HZCm2/nge. The scope of protection of the moon is subject to the definition of the patent application, whichever is well known to the skilled person, without departing from the invention. Any changes and modifications made within the spirit and scope of the invention are within the scope of protection of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a schematic cross-sectional view showing a conventional film bulk acoustic resonator. Figs. 2A to 2H are schematic cross-sectional views showing a method of manufacturing a film bulk acoustic resonator according to an embodiment of the present invention. Figure 4 is a cross-sectional view showing a resonant cavity of a film bulk acoustic resonator in accordance with another embodiment of the present invention, through a first surface of the substrate. Figure 4: Another specific embodiment of the present invention DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A cross-sectional view of an acoustic resonator of a film body 1334271. Fig. 5 is a diagram showing a frequency response of a film bulk acoustic resonator after plating various thicknesses of titanium metal according to an embodiment of the present invention. 6 is a graph showing the relationship between the mass load of the film bulk acoustic resonator and the amount of change in the resonant frequency according to an embodiment of the present invention. [Main element symbol description] 100 film bulk acoustic resonator 110 矽 substrate 111 first surface 112 second surface 113 resonant cavity 120 protective layer 130 surname mask layer 140 first electrode layer 150 piezoelectric layer 151 third surface 160 Two-electrode layer 200 film bulk acoustic resonator 210 矽 substrate 211 first surface 212 second surface 213 resonant cavity 213a bottom 220 protective layer 221 third sidewall 230 etch mask layer 240 first electrode layer 241 first sidewall 242 second sidewall 250 piezoelectric layer 251 chamber 260 second electrode layer