201027070 六、發明說明： 【發明所屬之技術領威】 本發明是有關於一種場效電晶體（Field Effect Transistor) 與具有該場效電晶體的感測電極’特別是指一種用於感測 酸鹼值的離子感測場效電晶體（Ion Sensitive Field Effect Transistor )與具有該離子感測場效電晶體的離子感測電 極。 【先前技術】 Φ 參閲圖1，離子感測場效電晶體1 (Ion Sensitive Field201027070 VI. Description of the Invention: [Technical Leadership of the Invention] The present invention relates to a field effect transistor and a sensing electrode having the field effect transistor, particularly for sensing acid A base value ion sensing field effect transistor (Ion Sensitive Field Effect Transistor) and an ion sensing electrode having the ion sensing field effect transistor. [Prior Art] Φ Refer to Figure 1, Ion Sensitive Field 1
Effect Transistor，以下簡稱IFET)的結構與金屬-氧化物-半 導禮場效電晶體（Metal-Oxide-Semiconductor Field Effect Transistor，以下簡稱MOSFET )相似，其包含有一由半導 體材料構成的半導體層11、一形成在該半導體層11上的導 電層12,及一形成在該半導體層11相反於該導電層12的 另一表面的感測層13，該感測層13會因待測物的酸鹼度而 產生一相對的電位變化，該導電層12與該感測層13電連 ® 接而可將該感測層13的電位變化向外輸出，藉此，可以量 測待測物的酸驗值。 參閲圖2，圖2是將上述離子感測場效電晶體1經過封 裝製程後而可實際應用於測量待測物酸鹼值變化的離子感 測電極，在結構上包含一與該離子場效電晶體1連結的封 裝絕緣膜14,及一與該離子場效電晶體1電連接的封裝座 15 ° 該絕緣封裝膜14形成在該離子感測場效電晶體1上， 3 201027070 且將該感測層π表面界定出—接觸制物的測試面⑶， 該封裝座15與該離子感測場效電晶體！的導電層12電連 接，並將該感測層13的電位變化向外輸出。 當將上述的離子感測電極與待測物接觸，例如置入具 有預定酸鹼值㈣/紐性水溶液巾時，該測試自⑶與該 水溶液接觸，藉由該測試面131與溶液中的氫離子產生吸〆 附鍵結而使該測試面131的電位產生變化，之後經過導電 層12、封裝座15向外輸出電信號後即可由此等電信號得 知待測物的氫離子濃度，⑽精確得知待測物的酸驗值。 由於氮化邦i3N4)或氧化邦办)與半導體層u的晶 格匹配度尚，且製程容易控制，因此是最常用在感測層Η 的構成材料ϋ錢切或二氧切為材韻成的單一 感測層13與待測物接觸時，其穩定度及線性度的表現較 差’所以得到的結果並不理想。 目前，則有以高介電常數的材料，例如氧化鋁 (Α12〇3)氧化鈕（Ta2〇5)、氧化锆（Zr〇2)、氧化铪（Hf〇d，或 氧化镨（Pr2〇3)構成感測層13，來增加感測層13的穩定性及 靈敏度而、昇離子感測電極的性能，然而這些材料的 種類及選擇性均不多，因此如何提供更多樣化的材料選 擇，以改善感測層的穩定性、靈敏度與線性度，以得到可 靠度精確度，及性能均佳的離子感測電極，是本技術領 域研究者持續不斷研究的目標。 【發明内容] 因此，本發明之目的，即在提供一種穩定性、靈敏度 201027070 與線性度均佳的離子感測場效電晶體。 另外，本發明之另一目的，亦在提供一種可靠度、精 確度，及性能均佳的具有離子感測場效電晶體的離子感測 電極。 於是，本發明一種離子感測場效電晶體，在接觸待測 物後因待測物的酸鹼值而可產生對應的電位，包含—半導 體層、一感測層，及一導電層。 該半導體層具有相反的一上表面與一下表面。 該感測層設置於該上表面’且至少包括—氧化釤的材 料，可在接觸待測物時因待測物的酸鹼值而可產生對應的 電位。 該導電層可導電並設置於該下表面，且與該感測層電 連接而可將該感測層的電位向外輸出。 另外，本發明一種具有離子感測場效電晶體的離子感測 電極，可供量測溶液中待測物之濃度，包含一離子感測場效 電晶體、一絕緣封裝膜，及一封裝座。 該離子感測場效電晶體包括一半導體層、一形成於該半 導體層上的感測層，及一形成於該半導體層之一相反於形成 有该感測層之表面的導電層，該感測層由至少具有氧化釤的 材料構成，而可因待測物的酸驗值產生一對應的電位，該導 電層可導電並與該感測層電連接。 該絕緣封裝膜形成在該離子感測場效電晶體上且將該感 測層表面界定出一接觸待測物的測試面。 該封裝座與該離子感測場效電晶體的導電層電連接，將 201027070 該感測層的電位向外輸出。 本發明之功效在於：以氧化釤為材料構成離子感測場 效電晶體的感測層，不僅具有極佳的耐酸、鹼性，且在不 同酸、驗性條件下均具有高靈敏度、高穩定度及高線性 度表現’進而可封裝得到可靠度、精確度’及性能均佳的 離子感測電極。 【實施方式】 有關本發明之前述及其他技術内容、特點與功效，在 以下配〇參考圖式之二個較佳實施例的詳細說明中，將可❹ 清楚的呈現。 在本發明被詳細描述之前，要注意的是，在以下的說 明内各中，類似的元件是以相同的編號來表示。 參閲圖3，本發明一種離子感測場效電晶體2的一第一 較佳實施例是包含一半導體& 21、分別形成在該半導體層 21相反兩面的-導電層22及一感測層23，該感測層η可 在接觸待測物後，因待測物㈣驗值而產生對應的電位。 類似於習知的離子感測場效電晶體，該半導體層21由© 半導體材料構成，具有相反的一上表面211與一下表面 212該導電層22由導電材料構成，形成在該下表面212 上於本實施例中該半導體層21是具有（1〇〇)晶向的ρ型矽 晶圓（p-type silicon wafer)所構成，該導電層22為由鋁所構 成且膜厚為300nm。 該感測層23形成該半導體層21之上表面211，由至少 包括氧化釤（Sm203)的材料構成’由於氧化彭具有高介電常 201027070 數、與該半導體層21間之晶格常數匹配度高、熱穩定性 佳，並與半導體層21間具有合適之能帶’因此極為適合用 於構成該感測層23。於本實施例中該感測層23是由氧化釤 為材料所構成。 另外，該感測層23是先在該半導體層21表面形成一 具預定膜厚之鍍膜，再於600〜900°C的溫度，30秒的條件 下進行快速熱退火（Rapid Thermal Annealing，RTA)使該鑛 膜的結構變緻密後，形成該感測層23。The effect Transistor (hereinafter referred to as IFET) has a structure similar to that of a Metal-Oxide-Semiconductor Field Effect Transistor (hereinafter referred to as MOSFET), and includes a semiconductor layer 11 made of a semiconductor material. a conductive layer 12 formed on the semiconductor layer 11, and a sensing layer 13 formed on the opposite surface of the semiconductor layer 11 opposite to the conductive layer 12, the sensing layer 13 may be due to the pH of the object to be tested A relative potential change is generated, and the conductive layer 12 is electrically connected to the sensing layer 13 to output the potential change of the sensing layer 13 outward, thereby measuring the acidity of the analyte. Referring to FIG. 2, FIG. 2 is an ion sensing electrode which can be practically applied to measure a change in the pH value of a test object after the ion sensing field effect transistor 1 is subjected to a packaging process, and includes an ion field in the structure. a package insulating film 14 connected to the effect transistor 1 and a package holder 15 electrically connected to the ion field effect transistor 1; the insulating package film 14 is formed on the ion sensing field effect transistor 1, 3 201027070 and The sensing layer π surface defines a test surface (3) that contacts the workpiece, and the package holder 15 and the ion sensing field effect transistor! The conductive layer 12 is electrically connected, and the potential change of the sensing layer 13 is outputted outward. When the ion sensing electrode is contacted with the analyte, for example, by placing a predetermined acid-base (4)/neutral aqueous solution, the test is contacted with the aqueous solution by (3), by using the test surface 131 and the hydrogen in the solution. The ion generates a suction bond to change the potential of the test surface 131, and then the electrical signal is outputted through the conductive layer 12 and the package 15 to obtain the hydrogen ion concentration of the analyte by the isoelectric signal, (10) Accurately know the acid value of the analyte. Due to the lattice matching degree of the nitriding state i3N4) or the oxide layer, and the process of the semiconductor layer u is still easy to control, it is the most commonly used component in the sensing layer ϋ 切 cut or dioxo cut into materials. When the single sensing layer 13 is in contact with the object to be tested, its stability and linearity are poorly performed, so the results obtained are not satisfactory. At present, there are materials with high dielectric constant, such as alumina (Α12〇3) oxidation button (Ta2〇5), zirconia (Zr〇2), yttrium oxide (Hf〇d, or yttrium oxide (Pr2〇3). The sensing layer 13 is configured to increase the stability and sensitivity of the sensing layer 13, and to improve the performance of the ion sensing electrode. However, the types and the selectivity of these materials are not many, so how to provide more diverse material selection. In order to improve the stability, sensitivity and linearity of the sensing layer, to obtain reliability accuracy and excellent performance of the ion sensing electrode, it is an object of continuous research by researchers in the technical field. The object of the present invention is to provide an ion sensing field effect transistor with good stability and sensitivity 201027070 and linearity. In addition, another object of the present invention is to provide a reliability, an accuracy, and a performance. Preferably, the ion sensing electrode has an ion sensing field effect transistor. Thus, the ion sensing field effect transistor of the present invention can generate a corresponding potential due to the pH value of the object to be tested after contacting the object to be tested. Contained - half a bulk layer, a sensing layer, and a conductive layer. The semiconductor layer has an opposite upper surface and a lower surface. The sensing layer is disposed on the upper surface and includes at least a material of cerium oxide, which is in contact with the object to be tested The corresponding potential may be generated due to the pH value of the analyte. The conductive layer may be electrically conductive and disposed on the lower surface, and electrically connected to the sensing layer to output the potential of the sensing layer to the outside. The invention provides an ion sensing electrode with an ion sensing field effect transistor, which can measure the concentration of the analyte in the solution, and comprises an ion sensing field effect transistor, an insulating encapsulation film, and a package holder. The ion sensing field effect transistor includes a semiconductor layer, a sensing layer formed on the semiconductor layer, and a conductive layer formed on one of the semiconductor layers opposite to a surface on which the sensing layer is formed. The measuring layer is composed of a material having at least cerium oxide, and a corresponding potential can be generated due to the acid value of the object to be tested, and the conductive layer can be electrically conductive and electrically connected to the sensing layer. The insulating packaging film is formed in the ion sensation. Field effect cell And the surface of the sensing layer defines a test surface contacting the object to be tested. The package seat is electrically connected to the conductive layer of the ion-sensing field-effect transistor, and the potential of the sensing layer of 201027070 is output to the outside. The invention has the advantages that the sensing layer of the ion sensing field effect transistor is made of cerium oxide as a material, which not only has excellent acid resistance and alkali resistance, but also has high sensitivity and high stability under different acid and test conditions. And high linearity performance 'and thus can be packaged to obtain reliability, accuracy' and ion sensing electrodes with good performance. [Embodiment] The foregoing and other technical contents, features and effects of the present invention are provided in the following reference drawings. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT(S) DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT(S) DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Before the present invention is described in detail, it is noted that in the following description, like elements are Said. Referring to FIG. 3, a first preferred embodiment of an ion-sensing field-effect transistor 2 of the present invention comprises a semiconductor & 21, a conductive layer 22 formed on opposite sides of the semiconductor layer 21, and a sensing The layer 23, the sensing layer η can generate a corresponding potential after the object to be tested is touched by the object (4). Similar to the conventional ion sensing field effect transistor, the semiconductor layer 21 is composed of a semiconductor material having an opposite upper surface 211 and a lower surface 212. The conductive layer 22 is composed of a conductive material formed on the lower surface 212. In the present embodiment, the semiconductor layer 21 is composed of a p-type silicon wafer having a (1 Å) crystal orientation, and the conductive layer 22 is made of aluminum and has a film thickness of 300 nm. The sensing layer 23 forms the upper surface 211 of the semiconductor layer 21, and is composed of a material including at least yttrium oxide (Sm203). Since the oxidized pen has a high dielectric constant of 201027070, the lattice constant matching degree with the semiconductor layer 21 It has high heat and thermal stability and has a suitable energy band between the semiconductor layer 21 and is therefore extremely suitable for constituting the sensing layer 23. In the present embodiment, the sensing layer 23 is made of yttrium oxide. In addition, the sensing layer 23 is formed on the surface of the semiconductor layer 21 with a predetermined film thickness, and then subjected to Rapid Thermal Annealing (RTA) at a temperature of 600 to 900 ° C for 30 seconds. After the structure of the mineral film is densified, the sensing layer 23 is formed.
當退火溫度小於700°C時，會產生較差的氧化釤晶格結 構，而當退火溫度大於900°C時，則容易形成釤氧矽化合物 (Sm-Silicate)，因此，較佳地，該感測層23的退火溫度是 在 700〜800°C。 再者’當感測層23的膜厚低於3nm時，由於會有穿遂 電流及電容不足等問題產生，因此會導致量測結果失真， 而當膜厚太高時則會增加製程時間及成本，因此，較佳 地，該感測層23的膜厚為介於3〜1〇〇nm。 ^上述的離子感測場效電晶體2與具有不同酸驗度之 待測物接觸時，該感測層23與待測物的氫離子產生吸附鍵 結而產生對應的電位，之後再經過導電層22向外輸出，即 可測得待測物的氫離子漠度，進而得到待測物的酸驗值。 參閱圖4纟發明該離子感測場效電晶體2可藉由封裝 ^程後形心圖4所示具有離子感測場效電晶冑2的離子 該離子感測電極包含-如該第-較佳實施所述 之離子感測場效電晶體2、—絕緣封裝膜3，及—封裝座 201027070 4 〇 該絕緣封裝膜3形成在該離子感測場效電晶體2上， 且將該感測層23表面界定出—接觸待測物的測試面231， 該封裝座4與該離子感測場效電晶體2的導電層22電連 接’將該感測層23的電位向外輸出。 將上述的離子感測電極與具有不同酸驗度之待測物接 觸’例如置人具有敎祕值的酸/或雜轉液中時，該 離子感測場效電晶體2的測試面231會直接與該水溶液接 觸’藉由該測試面231與水溶液中的氫離子產生吸附鍵結❹ 而使該測試面的電位產生變化，之後經過導電層22、封裝 座4向外輸出電信號後’即可由此等電信號得知待測物的 氫離子濃度。 由於該以氧化釤構成的感測層23具有高介電常數高 電合率、低漏電流、熱穩定性，以及良好的酸鹼耐受 度，因此以該具有離子感測場效電晶體2之離子感測電極 進行離子濃度量測時不僅可改善一般感測電極的感測層因 酸鹼度轉換時穩定度不佳之缺點外，並具有極佳的量測© 線性度。 參閱圖5，本發明該第二較佳實施例之離子感測場效電 00體2，其材料、組成與該第一較佳實施例大致相似不 同處在於該離子感測場效電晶體2，可更包含一形成在該感 測層23表面的酵素層24。 該酵素層24具有一可與待測物反應而產生酸鹼值變化 的酵素’藉由該酵素層24的酸鹼值變化，進而使與該酵素 201027070 層24連接的感測層23 #電位產生變化，經由兩階段的反 應而可據以進行量測溶液中待測成分的濃度，由於該酵素 的種類、反應機構等特性非為本發明的技術重點，因此， 在此不再多加說明。 參閱圖6 ’上述本發明該離子感測場效電晶體2,可藉由 封裝製程後形成如圖6所示之具有離子感測場效電晶體2, 的離子感測電極，該離子感測電極包含一如該第二較佳實 施例所述之離子感測場效電晶體2,、一絕緣封裝膜3，及一 _ 封裝座4。 該絕緣封裝膜3形成在該離子感測場效電晶想2,上並 將該感測層23表面界定出一測試面231，且該酵素層^為 开V成在該測試區231上，該封裝座4與該離子感測場效電 晶體2,的導電層22電連接，將該感測層23的電位向外輸 出。 將上述該具有酵素層24之離子感測電極置入一含有待 〇 測物之待測溶液中’該酵素層24與待測物反應後會產生酸 驗值變化’進而使與該酵素層24連接的感測層23受到該 酵素層24的酸驗值變化而產生電位變化，之後經過該導電 層22、封裝座4向外輸出電信號後，即可由此等電信號得 知待測物的濃度；例如欲檢測溶液中尿素的濃度，則該酵 素層24可具有一尿素酵素，經由該尿素酵素與溶液中之尿 素反應後產生之酸鹼值變化而使感測層23的電位產生變 P可用以量測出溶液中尿素的濃度，而可將該離子感 則電極更進一步的拓展到生物檢測的應用領域。 201027070 參閲圖7，圖7為以具有該第一較佳實施例之離子感測 場效電晶體2製得之離子感測電極，其感測層23經7〇〇t： 退火處理後，在不同酸鹼度條件下與電位之曲線圖。 由圖7之結果可知，該以氧化釤構成的感測層23在不 同的酸鹼度條件下，其線性度（linearity)實質為〇 992，感測 靈敏度（sensitivity)實質為56mV/pH，均可得到一良好之表 現結果。 參閱圖8 ’ ® 8 4α具有該第二較佳實施例之離子感測 場效電晶體2’製得之離子感測電極，在氬氣跟氧氣（Ar/〇2) ^ 氣體流速10: 4,在不同尿素濃度下與電位差的曲線圖。 由圖8結果可得知，在不同尿素濃度下之離子感測電 極的感測度為2.37mV/mM(±〇.U)，線性度為〇 98959 (±0.002)，均可得到一良好的性能表現，即，藉由該酵素層 24的設置可使該離子感測電極延伸到生物感測的應用領 域’而可在生物感測的應用上更進一步發展。 綜上所述，本發明以氧化釤構成離子感測場效電晶體 的感測層，由於氧化釤具有高介電常數、高電容率、低漏〇 電流、熱穩定性，以及良好的酸、鹼耐受度，因此以該離 子感測場效電晶體直接進行待測物之氫離子濃度量測時， 不僅可改善一般感測層因酸、鹼度轉換時的不穩定度，且 具有極佳的電極線性度，另外，可再藉由設置—與物質反 應後可產生酸鹼值變化的酵素層在該感測層上，經由該酵 素層及該感測層的兩階段反應而可準確的量測到待測物中 之待測成分的濃度，而可將該離子感測場效電晶體有效的 10 201027070 延伸運用到生物檢測的應用領域。 惟以上所述者，僅為本發明之較佳實施例而已，當不 能以此限定本發明實施之範圍，即大凡依本發明申請專利 範圍及發明說明内容所作之簡單的等效變化與修飾，皆仍 屬本發明專利涵蓋之範圍内。 【圖式簡單說明】 圖1是一示意圖，說明習知離子感測場效電晶體結 構； 圖2是一示意圖’說明習知離子感測電極的結構； 圖3疋一示思圖，說明本發明該離子感測場效電晶體 的第一較佳實施例； 圖4是說明以該第一較佳實施例製得的離子感測電極 結構； 圖5是一示意圖’說明本發明該離子感測場效電晶體 的第二較佳實施例； 圖6是說明以該第二較佳實施例製得的離子感測電極 結構； 圖7是說明以具有該第一較佳實施例之離子感測場效 電晶體製得的離子感測電極’其感測層經7〇〇°c退火處理 後’在不同酸驗度條件下與電位之曲線圖；及 圖8是說明以具有該第二較佳實施例之離子感測場效 電晶體製得之離子感測電極，在不同尿素濃度下與電位差 之曲線圖。 11 201027070 【主要元件符號說明】 2 離子感測場效電晶體 23 感測層 V 離子感測場效電晶體 24 酵素層 21 半導體層 3 絕緣封裝膜 22 導電層 4 封裝座 12When the annealing temperature is less than 700 ° C, a poor yttrium oxide lattice structure is produced, and when the annealing temperature is greater than 900 ° C, a Sm-Silicate is easily formed, and therefore, preferably, the feeling The annealing temperature of the measuring layer 23 is 700 to 800 °C. Furthermore, when the film thickness of the sensing layer 23 is less than 3 nm, problems such as a current flowing through the capacitor and insufficient capacitance may cause distortion of the measurement result, and when the film thickness is too high, the process time is increased. Cost, therefore, preferably, the thickness of the sensing layer 23 is between 3 and 1 〇〇 nm. When the above-mentioned ion-sensing field-effect transistor 2 is in contact with a test object having a different acidity, the sensing layer 23 and the hydrogen ion of the object to be tested generate an adsorption bond to generate a corresponding potential, and then pass through the conductive The layer 22 is outputted outward, and the hydrogen ion inversion of the object to be tested can be measured, thereby obtaining the acidity value of the object to be tested. Referring to FIG. 4, the ion-sensing field-effect transistor 2 can be formed by encapsulating the electrons having an ion-sensing field effect transistor 2 as shown in FIG. Preferably, the ion sensing field effect transistor 2, the insulating packaging film 3, and the package holder 201027070 4 are formed on the ion sensing field effect transistor 2, and the feeling is The surface of the layer 23 defines a test surface 231 that contacts the object to be tested, and the package holder 4 is electrically connected to the conductive layer 22 of the ion-sensing field-effect transistor 2 to output the potential of the sensing layer 23 outward. When the ion sensing electrode described above is brought into contact with an analyte having a different acidity, for example, in an acid/or hybrid liquid having a secret value, the test surface 231 of the ion sensing field effect transistor 2 is Directly contacting the aqueous solution, the potential of the test surface is changed by the contact of the test surface 231 with the hydrogen ions in the aqueous solution, and then the electrical conductivity is generated after the conductive layer 22 and the package 4 are externally outputted. The hydrogen ion concentration of the analyte can be known from the isoelectric signal. Since the sensing layer 23 composed of yttrium oxide has a high dielectric constant, high electrical conductivity, low leakage current, thermal stability, and good acid-base tolerance, the ion-sensing field-effect transistor 2 is used. The ion sensing electrode can not only improve the sensitivity of the sensing layer of the general sensing electrode due to poor stability during pH conversion, but also has excellent measurement © linearity. Referring to FIG. 5, the ion sensing field effect device 2 of the second preferred embodiment of the present invention is substantially similar in material and composition to the first preferred embodiment in the ion sensing field effect transistor 2 Further, an enzyme layer 24 formed on the surface of the sensing layer 23 may be further included. The enzyme layer 24 has an enzyme that reacts with the analyte to produce a change in pH value. The pH of the enzyme layer 24 changes, thereby causing the sensing layer 23 to be connected to the layer of the enzyme 201027070. The change can be measured by the two-stage reaction, and the concentration of the component to be tested in the solution can be measured. Since the characteristics of the enzyme, the reaction mechanism, and the like are not the technical points of the present invention, they will not be described here. Referring to FIG. 6 'the ion sensing field effect transistor 2 of the present invention, an ion sensing electrode having an ion sensing field effect transistor 2 as shown in FIG. 6 can be formed by a packaging process, and the ion sensing electrode is used. The electrode comprises an ion sensing field effect transistor 2 as described in the second preferred embodiment, an insulating encapsulation film 3, and a package holder 4. The insulating encapsulation film 3 is formed on the ion sensing field effect crystal 2, and defines a test surface 231 on the surface of the sensing layer 23, and the enzyme layer is formed on the test area 231. The package 4 is electrically connected to the conductive layer 22 of the ion-sensing field-effect transistor 2, and the potential of the sensing layer 23 is outputted outward. The ion sensing electrode having the enzyme layer 24 is placed in a solution to be tested containing the analyte to be tested, and the enzyme layer 24 reacts with the analyte to generate an acid value change, thereby causing the enzyme layer 24 to be reacted with the enzyme layer 24 . The connected sensing layer 23 is subjected to a change in the acid value of the enzyme layer 24 to generate a potential change, and then the electrical signal is outputted through the conductive layer 22 and the package 4 to obtain an electrical signal of the object to be tested. Concentration; for example, to detect the concentration of urea in the solution, the enzyme layer 24 may have a urease, and the potential of the sensing layer 23 is changed by the change in the pH value generated by the reaction between the urease and the urea in the solution. The concentration of urea in the solution can be measured, and the ion sensing electrode can be further extended to the application field of biological detection. 201027070 Referring to FIG. 7, FIG. 7 is an ion sensing electrode prepared by using the ion sensing field effect transistor 2 of the first preferred embodiment, after the sensing layer 23 is annealed by 7〇〇t: A plot of potential versus potential under different pH conditions. It can be seen from the results of FIG. 7 that the sensing layer 23 composed of yttrium oxide has a linearity of substantially 〇992 under different pH conditions, and a sensing sensitivity of substantially 56 mV/pH. A good performance result. Referring to Fig. 8 ' ® 8 4α having the ion sensing field effect transistor 2' of the second preferred embodiment, the ion sensing electrode is prepared in an argon gas with oxygen (Ar/〇2) ^ gas flow rate of 10:4 , a plot of potential difference at different urea concentrations. It can be seen from the results of Fig. 8 that the sensitivity of the ion sensing electrode at different urea concentrations is 2.37mV/mM (±〇.U), and the linearity is 〇98959 (±0.002), which can obtain a good performance. The performance, that is, the arrangement of the enzyme layer 24 allows the ion sensing electrode to extend to the field of biosensing applications, and can be further developed in biosensing applications. In summary, the present invention uses yttrium oxide to form a sensing layer of an ion-sensing field-effect transistor, since yttrium oxide has a high dielectric constant, a high permittivity, a low leakage current, thermal stability, and a good acid, Alkali tolerance, therefore, when the ion sensing field effect transistor directly measures the hydrogen ion concentration of the analyte, it can not only improve the instability of the general sensing layer due to acid and alkalinity conversion, but also has a pole Good electrode linearity, in addition, by setting - an enzyme layer that reacts with the substance to produce a change in pH value on the sensing layer, through the two-stage reaction of the enzyme layer and the sensing layer The measurement of the concentration of the component to be tested in the test object can be extended to the application field of the biological detection using the ion sensing field effect transistor effective 2010. The above is only the preferred embodiment of the present invention, and the scope of the invention is not limited thereto, that is, the simple equivalent changes and modifications made by the scope of the invention and the description of the invention are All remain within the scope of the invention patent. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic view showing a conventional ion sensing field effect transistor structure; FIG. 2 is a schematic view showing the structure of a conventional ion sensing electrode; FIG. 3 is a schematic diagram illustrating the present invention. A first preferred embodiment of the ion sensing field effect transistor is invented; FIG. 4 is a view showing the structure of the ion sensing electrode fabricated in the first preferred embodiment; and FIG. 5 is a schematic view illustrating the ion sensation of the present invention. A second preferred embodiment of the field effect transistor; Fig. 6 is a view showing the structure of the ion sensing electrode produced by the second preferred embodiment; Fig. 7 is a view showing the ion sensation of the first preferred embodiment; The ion sensing electrode prepared by the field effect transistor is characterized in that the sensing layer is annealed at 7°°c and then plotted with potential under different acidity conditions; and FIG. 8 is a description to have the second The ion sensing electrode prepared by the ion sensing field effect transistor of the preferred embodiment is a graph of potential difference at different urea concentrations. 11 201027070 [Key component symbol description] 2 Ion-sensing field effect transistor 23 Sensing layer V Ion sensing field effect transistor 24 Enzyme layer 21 Semiconductor layer 3 Insulating encapsulation film 22 Conductive layer 4 Package holder 12