TWI241650B - A wet etching method using electric-field-assisted proton exchange in LiNbO3 - Google Patents

Abstract

The invention is a novel technique to control die wet etching profile by applied electric field. It is based on the combination of electric-field-assisted proton exchange and the etching properties of domain inversion by using a mixture of HF and HNO3 acids to wet-etch lithium niobate. By appropriate electrode design and applied voltage, the direction and the rate of proton diffusion can be varied and the profile of the etched region can be controlled. The novel wet etching technique has the following advantages: (1) smooth etching surface; (2) large etching depth; (3) controllable etching sidewall profile; (4) low cost and potential for mass production. By utilizing the technique, various versatile devices, such as variable optical attenuator, wide-angle waveguide bend and optical power splitter, can be fabricated in lithium niobate.

Description

1241650 A7 B7 五、發明説明（1 ) 1.先前技術 (請先閲讀背面之注意事項再填寫本頁) 由於鈮酸鋰本身擁有良好的電光（electrooptic)、聲光 (acoustooptic)、壓電（piezoelectric)和非線性光學（nonlinear optic)等效應，所以廣泛地被應用在積體光學元件的製作上 。爲了製作多樣化的元件結構和提昇光電元件的效能，蝕 刻鈮酸鋰的技術是必須的，因此在元件製程中佔有很重要 的地位。 經濟部智慧財產局員工消費合作社印製 鈮酸鋰本身具有很強的抗蝕刻特性，一般的酸鹼不會 和其產生反應。傳統上用來蝕刻鈮酸鋰的方法分成乾式蝕 刻和濕式蝕刻兩大類。乾式蝕刻的方法包含有電漿蝕刻 (plasma etching)、濺擊蝕亥！J (sputter etching)和反應性離子餓 刻（reactive ion etching)三種，其蝕刻的速率非常緩慢，而 且所產生的蝕刻表面粗糙不平。在1992年，Laurell等人提 出濕式蝕刻鈮酸鋰的方法，他們利用硝酸和氫氟酸的混合 溶液，蝕刻已進行質子交換的區域，可以獲得約數// m的蝕 刻深度以及光滑的蝕刻表面。利用此項技術，各種脊型波 導以及相關的積體光學元件已被成功的製作出來，然而受 到質子側擴散的影響，蝕刻區域的側壁隨著質子交換時間 的改變，而有傾斜或曲線的外型，很難加以控制。 積體光學反射面鏡（integrated-optic reflection mirror)具 有低光損耗和良好控制光方向的能力，在光學積體電路中 是很重要的元件，要製作良好的積體光學反射面鏡 (integrated-optic reflection mirror)所使用的飽刻方法，必須 具有以下特性： 本紙張尺度適用中國國家標準（CNS ) A4規格（210X 297公釐） 4 1241650 A7 ___B7____ 五、發明説明（2 ) (1) 蝕刻表面平整； (2) 產生足夠的蝕刻深度； (請先閲讀背面之注意事項再填寫本頁) (3) 可產生可控制或垂直的蝕刻側壁。 雖然乾式蝕刻法能夠產生垂直的側壁，但其表面粗糙 ，會造成很大的光散射損耗；除此之外，由於蝕刻深度太 淺，可反射光場量較少，並不適合使用來製作積體光學反 射面鏡。由Laurell等人提出的濕式蝕刻法雖沒有上述的缺 點，但其非垂直和不可控制的蝕刻側壁會將光波反射至基 板而非波導中，造成很大的光反射損耗。 2.發明槪要 經濟部智慧財產局員工消費合作社印製 本發明之主要目的是提供一種可以控制蝕刻輪廓，甚 至可達到垂直蝕刻側壁（vertical sidewall)和平滑蝕刻表面的 新技術，此發明兼具有乾式蝕刻法的優點（垂直側壁）和 傳統濕式蝕刻法的優點（平滑蝕刻表面），同時剔除二者 的缺點，如乾式蝕刻法的蝕刻速率非常緩慢、蝕刻表面粗 糙、製程價格昂貴等缺點，以及濕式蝕刻法的蝕刻輪廓無 法控制等缺點。 本發明提出藉由電場輔助質子交換（electric-field-assisted proton exchange) 之新型鈮酸鋰濕式蝕刻技術 ，經由 適當的電極設計與外加電壓，成功製作出具有可控制側壁 輪廓的蝕刻區域，將可以在鈮酸鋰上製作出理想的積體光 學反射面鏡（integrated-optic reflection mirror)，對於未來製 作可調式光衰減器（tunable optical attenuator)、大角度彎曲 -- 本紙張尺度適用中國國家標準（CNS ) A4規格（210X297公釐） 1241650 A7 B7 五、發明説明（3 ) (請先閲讀背面之注意事項再填寫本頁) 波導（wide-angle waveguide bend)和大分岔角的功率分離器 (wide-branching-angle optical power splitter)有很大的幫助， 這些元件的整合將有助於增加積體光學元件積體密度，提 昇單一晶片的效能。本發明提出的新型鈮酸鋰濕式蝕刻技 術，同時具有乾式蝕刻和濕式蝕刻的優點，且製作方便、 成本低，未來將可應用在大量生產上，使積體光學元件的 應用更加普及。 3. 圖式簡要說明 圖一電場輔助質子交換法的電極結構和電場示意圖。 圖二在圖1結構中的（a)電位分布；（b)電場分布。 圖三電場加速質子交換後的正規化質子濃度，其外加 電壓分別爲：（a)V = 0 ; (b)V=l ; (c)V = 5。 圖四電場輔助質子交換區域的蝕刻輪廓，其外加電壓 分別爲：U)V = 0 ; (b)V=l ; (c)V = 2.5 ; (d)V = 5。 圖五電場輔助質子交換區域蝕刻輪廓的SEM圖片，其 外加電壓分別爲：（a)V = 0; (b)V = 20; (c)V = 50。 圖六外加電壓與蝕刻深度和垂直側壁的關係圖。 經濟部智慧財產局員工消費合作社印製 圖七本發明第一實施例之電極設計圖 圖八本發明第二實施例之電極設計圖 1241650 A7 B7 五、發明説明（4 ) 混合溶液時，只有質子交換區域會被移除，因此所顯露的 蝕刻區域便如同質子交換區域般，有著不可控制的蝕刻輪 廓側壁。傳統的濕式蝕刻法無法改善此一問題，因此無法 在鈮酸鋰上製作出積體光學反射面鏡（integrated-optic reflection mirror) 〇 質子側擴散是由於質子在橫方向上濃度梯度所造成， 爲了抑制側擴散，必須施加和濃度梯度反方向的作用力。 發明中所利用的作用力，是外加電壓在特殊設計電極所產 生的電場，所使用的電極結構如圖一所示。當質子交換進 行時，擴散質子受到電場的作用而向中央區域移動，使得 質子側擴散的程度受到控制。 圖二顯示理論上電場分布的情形，其結果是使用有限 兀素法（finite element method)來進行電極分析所獲得。所模 擬的電極結構具有以下的參數··上電極間隙l〃=20 // m，下 電極寬度m、基板厚度=500 // m。而在質子交換過 程中，上電極也同時被用來當作質子交換的遮罩（mask)。圖 中顯示，當外加電壓爲1伏特時，其電位及電場的分布情 形，此處縱座標 y = 0對應到晶片的表面。由圖二（b)可以發 現，在電極（或遮罩）邊緣處的電場方向是往下且指向電極開 口的中心，剛好與質子側擴散的方向相反，因此可以加以 利用，抑制質子的側擴散。至於在上電極（或遮罩）中心處， 電場的方向是指向正下方，因此可以使質子加速往下擴散 ，增加擴散的深度。 本紙張尺度適用中國國家標準（CNS ) A4規格（210X297公釐） (請先閲讀背面之注意事項再填寫本頁)1241650 A7 B7 V. Description of the invention (1) 1. Prior technology (please read the notes on the back before filling this page) Because lithium niobate itself has good electrooptic, acoustooptic, and piezoelectric ) And non-linear optics, so it is widely used in the manufacture of integrated optical elements. In order to make a variety of device structures and improve the efficiency of photovoltaic devices, the technology of etching lithium niobate is necessary, so it occupies a very important position in the device manufacturing process. Printed by the Consumer Cooperative of the Intellectual Property Bureau of the Ministry of Economic Affairs. Lithium niobate itself has strong anti-etching properties, and ordinary acids and bases will not react with it. The traditional methods for etching lithium niobate are divided into two categories: dry etching and wet etching. Dry etching methods include plasma etching and sputtering! There are three types: J (sputter etching) and reactive ion etching. The etching rate is very slow, and the resulting etching surface is rough and uneven. In 1992, Laurell et al. Proposed a method for wet etching of lithium niobate. They used a mixed solution of nitric acid and hydrofluoric acid to etch the area where proton exchange had been performed, to obtain an etching depth of about // m and a smooth etching surface. . Using this technology, various ridge waveguides and related integrated optical components have been successfully fabricated. However, due to the influence of proton-side diffusion, the sidewall of the etched area has a sloped or curved outer surface as the proton exchange time changes. Type, it is difficult to control. Integrated-optic reflection mirrors have low light loss and good ability to control the direction of light. They are very important components in optical integrated circuits. It is necessary to make good integrated-optic reflection mirrors. Optic reflection mirror) must have the following characteristics: This paper size applies the Chinese National Standard (CNS) A4 specification (210X 297 mm) 4 1241650 A7 ___B7____ 5. Description of the invention (2) (1) Etching surface Flat; (2) Generate sufficient etching depth; (Please read the precautions on the back before filling out this page) (3) Can produce controlled or vertical etched sidewalls. Although the dry etching method can produce vertical sidewalls, its surface is rough and it will cause a large light scattering loss. In addition, because the etching depth is too shallow and the amount of reflected light field is small, it is not suitable for use in making integrated products. Optical reflecting mirror. Although the wet etching method proposed by Laurell et al. Does not have the above-mentioned drawbacks, its non-vertical and uncontrollable etched sidewalls will reflect light waves to the substrate instead of the waveguide, causing a large light reflection loss. 2. Inventions: Printed by the Consumer Cooperatives of the Intellectual Property Bureau of the Ministry of Economics. The main purpose of the present invention is to provide a new technology that can control the etch profile, and even achieve vertical etched sidewalls and smooth etched surfaces. This invention has both It has the advantages of dry etching (vertical sidewall) and the advantages of traditional wet etching (smooth etching surface). At the same time, it eliminates the disadvantages of both methods, such as the very slow dry etching rate, rough etching surface, and expensive process. , And the etching contour of the wet etching method cannot be controlled. The present invention proposes a new type of lithium niobate wet etching technology using electric-field-assisted proton exchange. Through appropriate electrode design and applied voltage, an etched area with a controlled sidewall profile is successfully fabricated. The ideal integrated-optic reflection mirror can be made on lithium niobate. For the future production of tunable optical attenuator and large-angle bending-this paper size applies to Chinese national standards (CNS) A4 specification (210X297 mm) 1241650 A7 B7 V. Description of the invention (3) (Please read the precautions on the back before filling this page) Wide-angle waveguide bend and power splitter with large branch angle ( Wide-branching-angle optical power splitter) is of great help. The integration of these components will help increase the density of integrated optical components and improve the performance of a single chip. The novel lithium niobate wet etching technology proposed by the present invention has the advantages of both dry etching and wet etching, and is convenient to manufacture and low in cost. It will be applicable to mass production in the future, making the application of integrated optical elements more popular. 3. Brief description of the figure Figure 1. Schematic diagram of the electrode structure and electric field of the electric field assisted proton exchange method. Figure 2 (a) potential distribution; (b) electric field distribution in the structure of Figure 1. Figure 3. Normalized proton concentration after the electric field accelerates proton exchange. The applied voltages are: (a) V = 0; (b) V = l; (c) V = 5. Figure 4. Etching profile of the electric-field-assisted proton exchange region. The applied voltages are: U) V = 0; (b) V = 1; (c) V = 2.5; (d) V = 5. Fig. 5. SEM image of the etching profile of the electric field-assisted proton exchange region. The applied voltages are: (a) V = 0; (b) V = 20; (c) V = 50. Fig. 6. Relation between applied voltage, etching depth and vertical sidewall. Printed by the Consumer Cooperative of the Intellectual Property Bureau of the Ministry of Economic Affairs. VII. The electrode design of the first embodiment of the present invention. VIII. The electrode design of the second embodiment of the present invention. The exchange area is removed, so the exposed etched area is like a proton exchange area with uncontrollable etched profile sidewalls. Traditional wet etching methods cannot improve this problem, so integrated-optic reflection mirrors cannot be fabricated on lithium niobate. Proton side diffusion is caused by the concentration gradient of protons in the lateral direction. In order to suppress side diffusion, a force opposite to the concentration gradient must be applied. The applied force in the invention is the electric field generated by the applied voltage on the specially designed electrode. The electrode structure used is shown in Figure 1. When proton exchange is performed, the diffused protons are moved to the central region by the action of the electric field, so that the degree of proton-side diffusion is controlled. Figure 2 shows the theoretical distribution of the electric field. The result is obtained by electrode analysis using the finite element method. The simulated electrode structure has the following parameters: The upper electrode gap l〃 = 20 // m, the lower electrode width m, and the substrate thickness = 500 // m. In the proton exchange process, the upper electrode is also used as a mask for proton exchange. The figure shows the distribution of potential and electric field when the applied voltage is 1 volt. Here the vertical coordinate y = 0 corresponds to the surface of the wafer. From Figure 2 (b), it can be found that the direction of the electric field at the edge of the electrode (or mask) is downward and points to the center of the electrode opening, which is just opposite to the direction of the proton side diffusion, so it can be used to suppress the side diffusion of protons. . As for the center of the upper electrode (or mask), the direction of the electric field is directed directly downward, so the protons can be accelerated to diffuse downward, increasing the depth of diffusion. This paper size applies to Chinese National Standard (CNS) A4 (210X297 mm) (Please read the precautions on the back before filling this page)

經濟部智慧財產局員工消費合作社印製 ^•-tvPrinted by the Consumer Cooperatives of the Intellectual Property Bureau of the Ministry of Economic Affairs ^ • -tv

經濟部智慧財產局員工消費合作社印製 1241650 A7 B7 __ 五、發明説明（5 ) 質子在擴散過程中受到電場作用’所需遵守的擴散方 程式（diffusion equation)爲 ^ = V(i)-VC)+V(/i-C.£) (1) dt 其中C爲質子濃度、β爲擴散係數、五爲外加電場、#爲 質子遷移率、〖爲時間。爲了瞭解質子分布的情形，吾人使 用 alternating-direction-implicit method來解方程式（1)。在質 子交換過程中，質子是和鈮酸鋰中的鋰離子進行交換’鈮 酸鋰中有限的鋰離子晶格位置數，將會限制鈮酸鋰中質子 濃度。爲了滿足此一限制，在數値計算中，質子的濃度將 對可取代的鋰離子晶格位置濃度進行正規化，因此其最大 正規化濃度爲1。 考慮電場輔助質子交換（electric-field-assisted proton exchange)的條件爲：質子交換溫度T=240°C、質子交換時間 /=4 hr。圖三顯示，當外加電壓分別爲 0伏特、1伏特和 5伏特時，鈮酸鋰中正規化質子濃度的分布情形，圖中的等 位線分別對應質子正規化濃度爲0.1至1.0，濃度間隔爲0.1。 由圖三（a)發現，在未加電壓下，由於質子側擴散的緣故， 質子的分布會超越遮罩（mask)的邊緣（x= ±l〇/zm)約2//m 。當有外加電壓時，質子側擴散的情形明顯受到抑制，而 且由於往下電場的作用，中心的質子深度增加。當外加電 壓達5伏特時，質子濃度的分布明顯的往中心收縮，質子深 度更是比未加電壓時增加〇·9 // m。圖四顯示當外加電壓分 本纸張尺度適用中國國家標準（CNS ) A4規格（210X297公釐） ^ — (請先閲讀背面之注意事項再填寫本頁)Printed by the Consumer Cooperatives of the Intellectual Property Bureau of the Ministry of Economic Affairs 1241650 A7 B7 __ V. Description of the invention (5) The diffusion equation that the protons are subject to during the diffusion process must be followed by the diffusion equation ^ = V (i) -VC) + V (/iC.£) (1) dt where C is the proton concentration, β is the diffusion coefficient, five is the applied electric field, # is the proton mobility, and [is the time. To understand the distribution of protons, we used the alternating-direction-implicit method to solve equation (1). In the proton exchange process, protons are exchanged with lithium ions in lithium niobate. The limited number of lithium ion lattice positions in lithium niobate will limit the concentration of protons in lithium niobate. To meet this limitation, the proton concentration will normalize the replaceable lithium ion lattice position concentration in the numerical calculation, so its maximum normalized concentration is 1. The conditions for considering electric-field-assisted proton exchange are: proton exchange temperature T = 240 ° C, proton exchange time / = 4 hr. Figure 3 shows the distribution of normalized proton concentrations in lithium niobate when the applied voltages are 0 volts, 1 volts, and 5 volts. The isolines in the figure correspond to the normalized proton concentrations of 0.1 to 1.0, respectively. Is 0.1. It is found from Fig. 3 (a) that, under no voltage, the distribution of protons will exceed the edge of the mask (x = ± 10 / zm) by about 2 // m due to the proton side diffusion. When an applied voltage is applied, the proton side diffusion is significantly suppressed, and the proton depth in the center increases due to the downward electric field. When the applied voltage reaches 5 volts, the distribution of the proton concentration shrinks significantly toward the center, and the depth of the protons increases by 0.9 · m / m compared to the case without voltage. Figure 4 shows the applied voltage. The paper size is applicable to the Chinese National Standard (CNS) A4 specification (210X297 mm) ^ — (Please read the precautions on the back before filling this page)

1241650 A7 ____B7 五、發明説明（6 ) (請先閲讀背面之注意事項再填寫本頁) 別爲〇伏特、1伏特、2.5伏特、5伏特時，在蝕刻後所顯 露的蝕刻輪廓。由圖可知，在電壓V = 2.5伏特時，可以得 到深度約1 · 5 // m的垂直側壁。當外加電壓進一步增加時， 側擴散會被過度抑制而產生傾斜的情形。 經濟部智慧財產局員工消費合作社印製 爲了驗證理論模擬的結果，吾人使用所提出的新型濕 式蝕刻技術來進行實驗。首先，使用熱蒸鍍機在2切鈮酸鋰 晶片上鍍上厚度約3000A的鋁膜，然後利用微影術 (photolithography)在晶片正面製作電極的圖樣，最後使用鋁 蝕刻液完成正面電極的製作。至於背面電極的部分，亦可 使用上述相同的步驟來進行。接下來將晶片置於苯甲酸 (benzoic acid)中，在上下面電極加上預定的電壓，然後逐 漸將溫度上升至240 °C。加熱約4小時後，使其自然降溫至 室溫。在完成晶片淸洗後，置於硝酸和氫氟酸的混合溶液 中（HF._HN〇3=1:2)進行蝕刻，蝕刻時間超過6小時。圖五顯 示，當外加電壓分別是 0伏特、20伏特和50伏特時，蝕刻 輪廓的電子顯微鏡照片。圖五（a)爲未加電壓時的情形，此 時側壁有很明顯的傾斜。當外加電壓時，在接近晶片表面 處出現垂直的側壁，對應外加電壓爲20伏特和50伏特時， 垂直側壁的深度分別約爲0.66# m和1.12// m。圖六顯示垂直 蝕刻深度和全部蝕刻深度隨外加電壓增加的情形，由此可 知，外加電場可以有效抑制側擴散，應用此項技術，將可 控制蝕刻的輪廓。實驗的圖形與模擬的結果（圖四）相似 ，因此可以證明所提出的新型濕式蝕刻技術同時具有傳統 濕式蝕刻和乾式蝕刻的優點，可以製作出表面光滑、輪廓 本紙張尺度適用中國國家標準（CNS ) A4規格（210X297公釐） 5- 1241650 A7 B7 _ 五、發明説明（7 ) 可控制的蝕刻側壁，未來將可應用在鈮酸鋰上製作功能多 樣化的積體光學元件。 (請先閲讀背面之注意事項再填寫本頁) 本發明提出藉由電場輔助質子交換（electric-field-assisted proton exchange)之新型鈮酸鋰濕式蝕刻法， 經由適 當的電極設計與外加的電壓，已成功製作出具有垂直側壁 的蝕刻區域，且具有以下特性：（1)蝕刻表面平整；（2)蝕刻 深度大；（3)可以控制蝕刻輪廓，甚至可達成垂直側壁。未 來將可以在鈮酸鋰上製作出理想的積體光學反射面鏡 (integrated-optic reflection mirror) 〇 經濟部智慧財產局員工消費合作社印製 依照上述實施例，本發明提出一種新型的濕式蝕刻鈮 酸鋰的方法，從理論模擬得到蝕刻的輪廓，並在實驗上成 功地製作出表面平滑且可控制蝕刻輪廓的反射側壁。新的 触刻技術結合了電場輔助質子交換（electric-field-assisted proton exchange)和濕式蝕刻的技術，藉著適當設計的電極 結構和外加的電壓，改變質子擴散的方向和速率。在深度 方向上，可以使外加電場和質子擴散的方向同向，達到控 制質子交換速率或鈾刻深度的目的；在橫方向上，可以使 外加電場和側擴散的方向相反，藉著調整電場的大小，控 制側擴散的程度，進而控制蝕刻側壁的傾斜角，甚至使其 和基板垂直。用以上技術再配合濕式蝕刻方法，則可製作 出表面平整的蝕刻面。實驗結果顯示，蝕刻出的垂直側壁 深度可接近全部蝕刻深度的一半，且表面非常平滑，應用 此技術將可在鈮酸鋰上製作理想反射鏡面，對於未來製作 可調式光衰減器（tunable optical attenuator)、大角度彎曲波 --__ 本紙張尺度適用中國國家標準（CNS ) A4規格（21 OX 297公釐） 1241650 A7 B7 五、發明説明（8 ) 導（wide-angle waveguide bend)和大分贫角的功率分離器 (wide-branching-angle optical power splitter)有很大的幫助， 有助於增加積體光學元件積體化的密度，提昇單一晶片的 效能。新型濕式蝕刻法具有以下優點：（1)蝕刻表面平整； (2)蝕刻深度大；（3)可以控制蝕刻輪廓，甚至可達成垂直側 壁；（4)製作成本低廉，具有未來量產的潛力。 本發明以任何熟習此技藝者，在不脫離本發明之精神 和範圍內，所做之各種更動與潤飾均落在本發明之範圍內 ，因此本發明之專利保護範圍當視後附之申請專利範圍所 界定者爲準。 5.參考文獻 [1] C.L. Lee and C.L. Liu, “CF4 plasma etching on LiNbO3”， Ζρρλ 尸Ays. Ze/7·，vol· 35，pp. 756〜758，1979.1241650 A7 ____B7 V. Description of the invention (6) (Please read the precautions on the back before filling this page) When the voltage is 0 volts, 1 volt, 2.5 volts, or 5 volts, the etched contour exposed after etching. As can be seen from the figure, when the voltage V = 2.5 volts, vertical sidewalls with a depth of about 1 · 5 // m can be obtained. When the applied voltage is further increased, the side diffusion is excessively suppressed and a tilt occurs. Printed by the Consumer Cooperatives of the Intellectual Property Bureau of the Ministry of Economic Affairs. To verify the results of theoretical simulations, I used the proposed new wet etching technology for experiments. First, an aluminum film with a thickness of about 3000 A was plated on a two-cut lithium niobate wafer using a thermal evaporation machine, and then photolithography was used to produce an electrode pattern on the wafer front. Finally, an aluminum etching solution was used to complete the fabrication of the front electrode. . As for the part of the back electrode, the same procedure can be used. Next, the wafer is placed in benzoic acid, a predetermined voltage is applied to the upper and lower electrodes, and then the temperature is gradually increased to 240 ° C. After heating for about 4 hours, it was allowed to cool naturally to room temperature. After the wafer was cleaned, it was etched in a mixed solution of nitric acid and hydrofluoric acid (HF._HNO3 = 1: 2). The etching time was more than 6 hours. Figure 5 shows an electron micrograph of the etched profile when the applied voltages were 0 volts, 20 volts, and 50 volts, respectively. Figure 5 (a) shows the situation when no voltage is applied. At this time, the side wall has a significant slope. When a voltage is applied, vertical side walls appear near the surface of the wafer, corresponding to the applied voltage of 20 volts and 50 volts. The depth of the vertical side walls is approximately 0.66 # m and 1.12 // m, respectively. Figure 6 shows how the vertical etch depth and total etch depth increase with the applied voltage. It can be seen that the applied electric field can effectively suppress the side diffusion. The application of this technology can control the contour of the etch. The experimental graphics are similar to the simulation results (Figure 4), so it can be proved that the proposed new wet etching technology has the advantages of both traditional wet etching and dry etching. It can produce a smooth surface and a contour. The paper dimensions are applicable to Chinese national standards. (CNS) A4 specification (210X297 mm) 5- 1241650 A7 B7 _ 5. Description of the invention (7) Controllable etched sidewalls will be applied to lithium niobate in the future to make integrated optical elements with various functions. (Please read the notes on the back before filling this page) The present invention proposes a new type of lithium niobate wet etching method using electric field-assisted proton exchange, through proper electrode design and applied voltage Etched areas with vertical sidewalls have been successfully produced, and have the following characteristics: (1) the etching surface is flat; (2) the etching depth is large; (3) the etching profile can be controlled, and even vertical sidewalls can be achieved. In the future, ideal integrated-optic reflection mirrors can be fabricated on lithium niobate. 0 Printed by the Consumer Cooperative of the Intellectual Property Bureau of the Ministry of Economic Affairs. According to the above embodiment, the present invention proposes a new type of wet etching. The method of lithium niobate obtains the etched contour from theoretical simulation, and experimentally successfully produces a reflective sidewall with a smooth surface and a controllable etched contour. The new etch technique combines electric-field-assisted proton exchange and wet etching techniques. With proper design of the electrode structure and applied voltage, the direction and rate of proton diffusion can be changed. In the depth direction, the direction of the applied electric field and the proton diffusion can be made the same direction to control the proton exchange rate or the depth of the uranium engraving; in the horizontal direction, the direction of the applied electric field and the side diffusion can be reversed. Size, control the degree of side diffusion, and then control the inclination angle of the etched sidewall, or even make it perpendicular to the substrate. By using the above techniques in combination with the wet etching method, an etched surface with a flat surface can be produced. The experimental results show that the depth of the etched vertical sidewall can be close to half of the total etch depth, and the surface is very smooth. The application of this technology will make an ideal mirror surface on lithium niobate. ), Large-angle bending wave --__ This paper size applies to Chinese National Standard (CNS) A4 specification (21 OX 297 mm) 1241650 A7 B7 V. Description of the invention (8) Wide-angle waveguide bend and Oita angle The wide-branching-angle optical power splitter can greatly help to increase the density of integrated optical components and improve the performance of a single chip. The new wet etching method has the following advantages: (1) the etching surface is flat; (2) the etching depth is large; (3) the etching profile can be controlled, and even vertical sidewalls can be achieved; (4) the production cost is low and it has the potential for future mass production . Anyone skilled in this invention can make various modifications and retouches within the scope of the present invention without departing from the spirit and scope of the present invention. Therefore, the scope of patent protection of the present invention shall be regarded as the attached patent The scope defined shall prevail. 5. References [1] C.L. Lee and C.L. Liu, “CF4 plasma etching on LiNbO3”, Zρρλ Ays. Ze / 7 ·, vol · 35, pp. 756 ~ 758, 1979.

[2] Y. Ohmachi and J. Noda, “Electro-optic light modulator with branched ridge waveguide”，Appl. Phys. Lett., vol. 27, pp. 544〜546， 1975.[2] Y. Ohmachi and J. Noda, “Electro-optic light modulator with branched ridge waveguide”, Appl. Phys. Lett., Vol. 27, pp. 544 ~ 546, 1975.

[3] J. L. Jackel, R.E. Howard, E.L. Hu, and S.P. Lyman, “Reactive ion etching of LiNbCh’’， Appl· Phys· Lett., vol· 38，pp.907〜909，1981.[3] J. L. Jackel, R.E. Howard, E.L. Hu, and S.P. Lyman, “Reactive ion etching of LiNbCh’ ’, Appl. Phys. Lett., Vol. 38, pp.907 ~ 909, 1981.

[4] F. Laurel 1，J. Web j 〇rn, G. Arvidsson, and J. Holmberg, “Wet etching of proton-exchanged lithium niobate - a novel processing technique”， /, Lightwave Technol., vol. 10, no. 11，pp.1 606〜1 609, Nov. 1992. -- 本紙張尺度適用中.國國家標準（CNS ) A4規格（210X 297公釐） (請先閲讀背面之注意事項再填寫本頁) 裝· 經濟部智慧財產局員工消費合作社印製 1241650 A7 B7 五、發明説明（9 ) [5] H. J. Lee and S. Y. Shin, “Lithium niobate ridge waveguides fabricated by wet ething’’， Electron. Lett., vol· 31，no.4，pp. 268〜269，Feb. 1995.[4] F. Laurel 1, J. Web j 〇rn, G. Arvidsson, and J. Holmberg, "Wet etching of proton-exchanged lithium niobate-a novel processing technique", /, Lightwave Technol., Vol. 10, no. 11, pp.1 606 ~ 1 609, Nov. 1992.-This paper size is applicable. National Standard (CNS) A4 (210X 297 mm) (Please read the precautions on the back before filling this page ) Printed by the Consumer Cooperatives of the Intellectual Property Bureau of the Ministry of Economic Affairs 1241650 A7 B7 V. Invention Description (9) [5] HJ Lee and SY Shin, “Lithium niobate ridge waveguides fabricated by wet ething”, Electron. Lett., Vol · 31, no.4, pp. 268 ~ 269, Feb. 1995.

[6] R.S. Cheng, T.J. Wang, and W.S. Wang, <{Wet-etched ridge waveguides in Y-cut lithium niobate’’， J· Lightwave Technol., vol. 15, no. 10, pp. 1 880-1 887, Oct. 1997. (請先閲讀背面之注意事項再填寫本頁) -裝· 經濟部智慧財產局員工消費合作社印製 本紙張尺度適用中國國家標準（CNS ) A4規格（210 X 297公釐）[6] RS Cheng, TJ Wang, and WS Wang, < {Wet-etched ridge waveguides in Y-cut lithium niobate '', J. Lightwave Technol., Vol. 15, no. 10, pp. 1 880-1 887, Oct. 1997. (Please read the notes on the back before filling out this page)-Installed · Printed on the paper by the Consumers' Cooperative of the Intellectual Property Bureau of the Ministry of Economic Affairs, this paper is sized for the Chinese National Standard (CNS) A4 (210 X 297 mm) )

Claims (1)

1241650 申請專利範圍 桌9 1 1 1 2 4 2 7號專利申請案 修正ί 中文申請專利範圍修正呆一 _______：__·ίβι — (請先閱讀背面之注意事項再填寫本頁) i乎月日 Λ 民國卜3年1 1月30 ^修正 1. 一種濕式鈾刻的方法，其蝕刻的輪廓與深度，係藉由 外加電壓於至少一對電極所產生的電場加以控制，其中藉 由電場輔助質子交換，應用電場控制質子分布，然後以氫 氟/酸和硝酸的混合溶液將質子分布區移除，應用此技術來 控制蝕刻輪廓，以進行鈮酸鋰的濕式刻。 2 ·依申請專利範圍第1項所述的方法，其中該至少一對 電極可產生最適合的電場，用以控制離子分布，進而得到 所需的蝕刻輪廓。 3 ·依申請專利範圍第1項所述之方法，藉由電場輔助質 子父換之銀酸鋰濕式鈾刻法，其中所述不同之電極設計係 用以產生逐漸集中之電場。 4 ·如申請專利範圍第1項所述之方法，其中該至少一對 電極，可由如鋁、鎳、金、鈦、鉻等之導電材料中之任一 種製成。 經濟部智慧財產局員工消費合作社印製 5·如申請專利範圍第2項所述之方法，進一步包含至少 一非金屬絕緣材料用以抑制不當離子擴散，且該非金屬絕 緣材料爲二氧化矽、二氧化鈦、氧化鎂等之不可導電絕緣 材料。 6 ·如申請專利範圍第1項所述之方法，其中所使用質子 交換溶液係爲苯甲酸、磷酸等之可供做爲質子交換溶液。 7·如申請專利範圍第1項所述之方法，該方法係應用於 本紙張尺度適用中國國家標準（CNS ) Α4規格（210X297公釐） 經濟部智慧財產局員工消費合作社印製 1241650 b Co D8 六、申請專利範圍 製作積體光學元件。 9 (請先閱讀背面之注意事項再填寫本頁) 本纸張尺度適用中國國家摞準（CNS ) A4規格（210X 297公釐） 21241650 Table of Patent Application Scope 9 1 1 1 2 4 2 7 Amendment of Patent Application Chinese Patent Application Amendment _______: __ · ί βι — (Please read the notes on the back before filling this page) Λ Republic of China 3 years 1 January 30 ^ Amendment 1. A method of wet uranium engraving, the contour and depth of the etching are controlled by an electric field generated by applying a voltage to at least a pair of electrodes, and the electric field is used to assist Proton exchange, the electric field is used to control the proton distribution, and then the proton distribution area is removed with a mixed solution of hydrofluoric / acid and nitric acid. This technique is used to control the etching profile for wet etching of lithium niobate. 2. The method according to item 1 of the scope of the patent application, wherein the at least one pair of electrodes can generate the most suitable electric field to control the ion distribution to obtain the desired etching profile. 3. According to the method described in item 1 of the scope of the patent application, the electric proton-exchanged lithium silverate wet uranium engraving method is assisted by an electric field, wherein the different electrode designs are used to generate a gradually concentrated electric field. 4. The method according to item 1 of the scope of patent application, wherein the at least one pair of electrodes may be made of any one of conductive materials such as aluminum, nickel, gold, titanium, chromium and the like. Printed by the Consumer Cooperatives of the Intellectual Property Bureau of the Ministry of Economic Affairs 5. The method described in item 2 of the scope of patent application, further comprising at least one non-metallic insulating material to suppress improper ion diffusion, and the non-metallic insulating material is silicon dioxide, titanium dioxide , Magnesium oxide and other non-conductive insulation materials. 6. The method as described in item 1 of the scope of patent application, wherein the proton exchange solution used is benzoic acid, phosphoric acid, etc., which can be used as the proton exchange solution. 7. The method as described in item 1 of the scope of patent application, which is applied to the paper standard applicable to the Chinese National Standard (CNS) A4 specification (210X297 mm) Printed by the Intellectual Property Bureau of the Ministry of Economic Affairs Consumer Cooperatives 1241650 b Co D8 Sixth, the scope of patent application for manufacturing integrated optical elements. 9 (Please read the notes on the back before filling out this page) This paper size is applicable to China National Standard (CNS) A4 size (210X 297 mm) 2