201131226 六、發明說明： 【發明所屬之技術領域】 本發明係，-種波導結構及其製造方法；特別是關於 一種石夕波導賴及·造方法，係底域刻之方法於基板 上形成一波導。 【先前技術】 Φ 由於現今科技的快速發展，人們對資訊處理 來越龐大’隨著積體電路製程技術的發展，單一晶片内電^ 數目逐年數量級的增加，現今一個微小的晶片内存在著數百萬 個電晶體，這使得單-晶片内計算處理速度越來越快。然而， 人們對傳遞訊息的需求量’改變了傳統的傳輸方式，此新的傳 輸方式㈤要更同的頻寬技術，以能跟上處理器的性能。 於早-晶片上，傳統晶片傳輸方式是藉由金屬線來 亦即所明的電互連〔細⑽如⑽肋⑽—〕，此方式 =制了，輸的速度’也造成多餘的能量消耗，其傳輸已不及目 』处理益的性此。因此，將光纖通訊的概念應用於晶片間的傳 製作光子整合電路〔Photonic Integrated Circuits; 藉由光來傳遞，即是以光的互連〔optical 八，/1〇n〕方式’於晶片上利用光波導做為訊號傳輸媒 此。將光^電tl件串連成一網路。由於利用了光來做傳輸，因 —值達U頻寬以及低損耗的特性。再者’由於糊光波導進 輸因此有利於整合多樣性的光電元件並將其積體化而 m 3 201131226 且也沒有串擾〔crosstalk〕的問題。此外，由於不須考慮電的 特性，因此沒有所謂的「阻抗匹配」等問題。 一般CMOS電路大多都製作於矽基板，為了解決資料傳 輸頻見的限制，因此矽基光電積體電路〔Si_based 〇pt〇-Electronic Integrated Circuits;灿―〇mCs〕是一個解 決的方式，此結構是將電的鶴和控機合光元件於一個晶片 中。-般積體電路傳輸方式有別於光電積體電路，在光電積體 電路中數娜輸和互奴_祕導進行雜，目此在錄光 電積體電路巾設計婦抑光波導是相#重要的作為連結傳 輪光訊號。 由於-般⑦基板並沒有侷限光場的能力，因此大多石夕波 導疋利用絕緣層上覆矽」〔Silic〇n 〇n如油⑽；⑽〕的技 術’才可㈣作it}魏力將光紐的波導結構。參考第i圖， 其顯示制S〇1結構的製造方法。首先树晶1ΠΗ)上以氧化 方式長上-層氧化層112’再以離子〔H+〕轟擊的方式在石夕晶 圓則上產生斷鍵118〔步驟1〕，接著將石夕晶圓12〇利用黏 5〔bonding〕的技術與石夕晶圓】黏合於一起〔步驟2〕。由 於離子轟擊所產生的斷鍵118造成晶圓11〇斷裂〔步驟3〕， 此斷裂面再經研磨拋光後即完成s〇I晶圓結構13〇〔步驟4〕。 然而，由於二氧切其導熱效率較差，頻導熱係數為 148W/(m · K) ’而二氧化矽的導熱係數為1以胃^ · κ)。兩 者之間相差有兩健量級，顯示著⑽結構不易散熱，此限制 201131226 了元件的效率和壽命。再者⑽結構也*賴且其最大 的缺點疋’絕緣層频結構非常不易與現行標準的石夕製程 結合。因贿在輕改善傳驗導結構及造方法之需求。 有4a於此纟翻為了滿足上述需求，其提供—種石夕波 導的製造方法，係姻底她_方式，製造_波導。 【發明内容】 本發明之目的係提供—種波導結構之製造方法，係利用 底切蝕刻之方法於基板上形成一波導。 為了達成上述目的，本發明較佳實施例之波導結構之製 造方法，包含下列步驟： ^ 於一基板上形成一樑脊；及 對該樑脊進行底切蝕刻。 本發明較佳實施例之波導結構之製造方法，其中該基板 及該樑脊係由矽所構成。 本發明較佳實施例之波導結構之製造方法，更包含： 對該樑脊進行氧化處理。 本發明較佳實施例之波導結構之製造方法’其中係以非 等向性的反應性離子蝕刻於該基板上形成該樑脊。 本發明較佳實施例之波導結構之製造方法，其中該樑脊 之寬度約6微米、高度約3至4微米，且於底切蝕刻後其底部 之寬度約為2微米。 本發明較佳實施例之波導結構之製造方法，其中係以電 201131226 子迴旋共振式離子反應蝕刻對該樑脊進行底切蝕刻。 本發明之另-目的係提供—種以上述方法所製作出的波 導結構。 【實施方式】 為了充分瞭解本發明’於下文將轉較佳實施例並配合 所附圖式作詳細說明，且其並非用以限定本發明。 第2至4圖揭示本發明較佳實施例之石夕波導結構之製造 • 方法。首先’以超音波震洗的方式將-發基板210的表面清 洗，再以餘刻的方式，例如以非等向性#咖咖〕反應 性離子蝕刻〔Reaetive lGn Eiehing; 〕挪基板則上形成 -石夕的樑脊(ridge)波導結構22〇，其寬度W1約6微米、高度 Η約3至4微米，亦即在石夕基板21〇上形成有以石夕製成的一條 狀突起〔參縣2圖〕。接著，再以濕侧或乾侧之製程， 例如藉由好城共料〔Ele_n eyd自n Res_ee; > ECR〕離子反應敍刻對樑脊22G進行等向性的底切㈣如刪 餘」使得樑脊220形成上寬下窄的結構亦即樑脊22〇包含 有下樑脊222與-上樑脊224，其中下標脊222的寬度— 〗於2微米’上樑脊224則位在下樑脊拉上，且其寬度大於 下樑脊222的寬度〔參照第3圖〕。 在上述底她刻所製作的上樑脊224波導結構中，雖然 其_材料料折射枝3 5 _，由較理論中並不滿足全 反射定律i_本發明II由底切蝴的方式，改變其波導形狀， 201131226 使底切餘刻區域的有效折射率降低〔參照第5圖〕，讓光場能 夠偈限在具有波導結構的上樑脊224中，而不會散逸於祕板 210 〇 在本發日种，由於制了植來料_鮮因此姓 刻時會造成邊壁（sidewall)的_。另外，為了縮小波導核 心孔徑來彌觀職度的極限，可將上述的波導結構送至高溫 爐氧化，使得基板2K)的表面212以及下樑脊222氧化形成二 氧化石夕〔Si〇2〕，而上樑脊224的表面现亦形成有一層二氧 化石夕〔參照第4圖〕，其厚度可藉由控制製程參數來調整。以 此方式’因乾姓刻所造成邊壁的粗糙可降低，而上樑脊224波 導結構的光場侷限能力亦能夠增加。 根據本發雜佳實關之赠導結構及製造方法，利用 習知半導體製㈣底城财式錢變波導職，藉此使底切 餘刻區域的有效折射轉低’讓光場麟舰在波導結構中， 不會散失在基板。除此之外’本發.佳實賴之⑦波導結構 製造方料會關CM〇S的方式，衫會有絲的問題， 且製造成本較低也較容易。 前述較佳實施例僅舉例說明本發明及其技術特徵，該實 施例之技術仍可適當進行各種實質等效修飾及/或替換方式予 以實施，因此’本發明之權利範圍須視後附申請專利範圍所界 定之範圍為準。 201131226 【圖式簡單說明】 第1圖··習用SOI結構的製造方法》 第2至4圖：本發明較佳實施例之矽波導結構之製造方 法之步驟。 第5圖：為本發明較佳實施例之矽波導結構_底切蝕刻 區域的有效折射率。 【主要元件符號說明】 112氧化層 120碎晶圓 210基板 220樑脊 224上樑脊 Η 高度 W2 寬度 110矽晶圓 118 斷鍵 130 SOI晶圓結構 212表面 222下樑脊 226表面 W1寬度201131226 VI. Description of the Invention: [Technical Field] The present invention relates to a waveguide structure and a method of fabricating the same, and more particularly to a method for fabricating a method for forming a substrate on a substrate waveguide. [Prior Art] Φ Due to the rapid development of today's technology, the greater the information processing, the number of devices in a single chip increases with the development of integrated circuit process technology. Today, there is a tiny number of wafers. Millions of transistors, which make the processing speed in a single-chip faster and faster. However, the demand for message delivery has changed the traditional transmission method. This new transmission method (5) requires more bandwidth technology to keep up with the performance of the processor. On the early-wafer, the traditional wafer transfer method is through the metal wire, that is, the known electrical interconnection [fine (10) such as (10) rib (10) -], this way = system, the speed of transmission 'also causes excess energy consumption The transmission has not been able to handle the benefits of this. Therefore, the concept of optical fiber communication is applied to inter-wafer photonic integrated circuits (Photonic Integrated Circuits; by optical transmission, that is, optical interconnection (optical, /1〇n] way] on the wafer The optical waveguide acts as a signal transmission medium. Connect the light and electricity tl pieces into a network. Since the light is used for transmission, the value is U-bandwidth and low-loss. Furthermore, since the paste optical waveguide is fed, it is advantageous to integrate and integrate the diverse photovoltaic elements with m 3 201131226 and there is no crosstalk problem. In addition, since there is no need to consider the characteristics of electricity, there is no such problem as "impedance matching". In general, CMOS circuits are mostly fabricated on germanium substrates. In order to solve the limitation of data transmission, the Si-based optoelectronic integrated circuits [Si_based 〇pt〇-Electronic Integrated Circuits; Can-〇mCs] is a solution. The electric crane and the control unit are combined in one wafer. - The integrated circuit transmission method is different from the optoelectronic integrated circuit. In the optoelectronic integrated circuit, the number of nano-transmissions and mutual slaves are secreted. The purpose is to record the optoelectronic integrated circuit. Important as a link to the light signal. Since the 7-substrate does not have the ability to limit the light field, most of the 夕 疋 疋 疋 疋 疋 疋 Si Si Si Si Si Si Si Si Si Si Si Si Si Si Si Si Si Si Si Si Si Si Si Si Si Si Si Si Si Si Si Si Si Si Si Si Si Si Si Si Si The waveguide structure of the light. Referring to Fig. i, it shows a manufacturing method of the S〇1 structure. First, the tree crystal 1') is oxidized to form the upper layer oxide layer 112' and then the ion [H+] bombardment method is used to generate the break key 118 on the Shixi wafer (step 1), and then the Shixi wafer 12〇 Bonded together with Shi Xi Wafer using the bonding technology [Step 2]. The breakage key 118 generated by the ion bombardment causes the wafer 11 to be broken [Step 3], and the fracture surface is polished and polished to complete the wafer structure 13 [Step 4]. However, since the dioxotomy has a poor thermal conductivity, the frequency thermal conductivity is 148 W/(m · K) ' and the thermal conductivity of cerium oxide is 1 to the stomach ^ κ). There are two levels of difference between the two, which shows that (10) the structure is not easy to dissipate heat, and this limit 201131226 has the efficiency and life of the component. Furthermore, the structure of (10) also depends on its biggest disadvantage. The insulation layer frequency structure is very difficult to combine with the current standard Shixi process. Because of the bribery, the need to improve the structure and method of inspection and guidance. In order to meet the above requirements, there is a 4a in this way, which provides a method of manufacturing the stone-wave waveguide, which is the result of her marriage. SUMMARY OF THE INVENTION An object of the present invention is to provide a method for fabricating a waveguide structure by forming a waveguide on a substrate by undercut etching. In order to achieve the above object, a method of fabricating a waveguide structure according to a preferred embodiment of the present invention comprises the steps of: forming a beam ridge on a substrate; and undercut etching the beam ridge. A method of fabricating a waveguide structure according to a preferred embodiment of the present invention, wherein the substrate and the beam ridge are formed of tantalum. A method of fabricating a waveguide structure according to a preferred embodiment of the present invention further comprises: oxidizing the beam ridge. A method of fabricating a waveguide structure according to a preferred embodiment of the present invention is wherein the beam is formed by anisotropic reactive ion etching on the substrate. A method of fabricating a waveguide structure in accordance with a preferred embodiment of the present invention, wherein the beam ridge has a width of about 6 microns, a height of about 3 to 4 microns, and a bottom portion having a width of about 2 microns after undercut etching. In a method of fabricating a waveguide structure according to a preferred embodiment of the present invention, the beam ridge is undercut etched by an electric 201131226 sub-cyclotron resonance ion-exchange etching. Another object of the present invention is to provide a waveguide structure produced by the above method. The invention is described in detail below with reference to the preferred embodiments of the invention, and is not intended to limit the invention. Figures 2 through 4 illustrate the fabrication of a stone-like waveguide structure in accordance with a preferred embodiment of the present invention. Firstly, the surface of the substrate 210 is cleaned by ultrasonic vibration washing, and then formed on the substrate by a reactive etching, such as an anisotropic method, for example, by a non-isotropic method (Reaetive lGn Eiehing; - Shi Xi's ridge waveguide structure 22 〇 having a width W1 of about 6 μm and a height of about 3 to 4 μm, that is, a strip-like protrusion formed by Shi Xi is formed on the 夕 基板 substrate 21 〔 [ Shen County 2 map]. Then, on the wet side or the dry side, for example, by the eutectic [Ele_n eyd from n Res_ee; > ECR] ion reaction, the isotropic bottom cut of the beam ridge 22G (4) is deleted. The beam ridge 220 is formed to have an upper width and a lower narrow structure, that is, the beam ridge 22 〇 includes a lower beam ridge 222 and an upper beam ridge 224, wherein the width of the subscript ridge 222 is at 2 micron 'the upper beam ridge 224 is located below The beam ridge is pulled up and its width is greater than the width of the lower beam ridge 222 (refer to Fig. 3). In the above-mentioned upper beam ridge 224 waveguide structure, although the _ material material refracts the branch 3 5 _, it is not theoretically satisfied that the total reflection law i_ the invention II is changed by the undercut butterfly Its waveguide shape, 201131226 reduces the effective refractive index of the undercut region [refer to Figure 5], allowing the light field to be limited to the upper beam ridge 224 having the waveguide structure without dissipating the secret plate 210. This type of hair, due to the production of planting materials _ fresh, so the name will cause the side wall (sidewall) _. In addition, in order to reduce the waveguide core aperture to the limit of the duty, the above waveguide structure can be sent to a high temperature furnace for oxidation, so that the surface 212 of the substrate 2K) and the lower beam 222 are oxidized to form a dioxide (Si〇2). The surface of the upper beam ridge 224 is also formed with a layer of dioxide (see Figure 4), the thickness of which can be adjusted by controlling the process parameters. In this way, the roughness of the side wall caused by the dry name can be reduced, and the optical field limitation ability of the upper beam ridge 224 waveguide structure can also be increased. According to the gift-giving structure and manufacturing method of this issue, the use of the well-known semiconductor system (4) to change the effective refraction of the undercut region to make the light field In the waveguide structure, it is not lost in the substrate. In addition to this, 'Benfa. Jiashi Lai's 7-wave structure manufacturing method will close the way of CM〇S, the shirt will have silk problems, and the manufacturing cost is lower. The foregoing preferred embodiments are merely illustrative of the present invention and its technical features, and the technology of the embodiments can be implemented by various substantial equivalent modifications and/or alternatives, and the scope of the present invention is subject to the appended claims. The scope defined by the scope shall prevail. 201131226 [Simplified Schematic Description] Fig. 1 is a view showing a manufacturing method of a conventional SOI structure. Figs. 2 to 4 are steps of a method of manufacturing a waveguide structure of a preferred embodiment of the present invention. Figure 5 is an effective refractive index of a 矽 waveguide structure _ undercut etched region in accordance with a preferred embodiment of the present invention. [Main component symbol description] 112 oxide layer 120 shredded wafer 210 substrate 220 beam ridge 224 upper beam ridge 高度 height W2 width 110 矽 wafer 118 broken key 130 SOI wafer structure 212 surface 222 lower beam ridge 226 surface W1 width