200928605 九、發明說明： 【發明所屬之技術領域】 本發明係關於-種極紫外光（EUV)微影術用光學元件及 其光學面之表面處理方法。 【先前技術】 在微影技術巾，迄今為止仍廣泛使用藉由將精細電路圖 案轉移至晶圓上而製造積體電路之曝光工具。隨著積體電 路朝更高整合程度、《高速度及£高功能的方向發展之趨 勢，正進行積體電路之改進。因此，需要曝光工具以長焦 深在晶圓表面形成具有高解析度之電路圖案影像，且正進 行曝光用光之波長的縮短。曝光光源係由習知g_射線（波 長.436 nm)、i-射線（波長：365 nm)及KrF準分子雷射（波 長：248 nm)進一步改進，且ArF準分子雷射（波長：193 nm) 即將投入使用。此外，為應對電路線寬將變成不大於7〇 ηπ1 的下一代積體電路，將皆使用ArF準分子雷射之浸潰式曝 光技術（immersion exposure technique)及雙重曝光技術 (double exposure technique)視為主導。然而，認為即使該 等技術亦僅將能约覆蓋線寬高達45 nm的一代。 在前述技術趨勢下，認為使用EUV光作為下一代曝光用 光之微影技術適用於32 nm及其後之代且正引起關注。如 本文所提及之EUV光係指波長在軟X射線區域或真空紫外 區域之光，尤其具有約0.2至100 nm之波長的光。目前， 在研究使用13.5 nm之微影光源。此EUV微影術（在下文縮 寫成”EUVL”）之曝光原理等同於使用投影光學系統轉移光 134992.doc 200928605 罩圖案之習知微影術的曝光原理。然而’因為不存在於 EUV光能區域透光之材料，故不可使用折射光學系統。因 此’必然要使用反射光學系統（參見專利文獻1)。 用於EUVL之反射光學系統之實例包括反射型光罩及鏡 面，諸如集光光學系統鏡面、照明光學系統鏡面及投影光 學系統鏡面。 反射型光罩主要包含（l)EUVL用光學元件（例如，玻璃基 板）、（2)EUVL用光學元件之光學面上所形成之反射性多層 薄膜’及（3)反射性多層薄膜上所形成之吸收層。另一方 面，鏡面主要包含（l)EUVL用光學元件（例如，玻璃基板） 及（2)EUVL用光學元件之光學面上所形成之反射性多層薄 膜。 使用具有如下結構者作為反射性多層薄膜：在該結構 中’對曝光用光之波長具有不同折射率之複數種材料彼此 以奈米級尺寸循環層壓。Mo及Si係已知的材料之代表性實 例。此外，已研究Ta及Cr用作吸收層。 作為EUVL用光學元件，需要具有低熱膨脹係數之材料 以便即使在用EUV光輻照後亦不產生應變，且已研究使用 具有低熱膨脹係數之玻璃或具有低熱膨脹係數之玻璃-陶 瓷。在本說明書中，將具有低熱膨脹係數之玻璃及具有低 熱膨脹係數之玻璃-陶瓷於下文共同稱為”低膨脹玻璃,,或 ”極低膨脹玻璃”。 作為此種低膨脹玻璃及極低膨脹玻璃，最廣泛使用為降 低玻璃熱膨脹係數之目的而添加摻雜劑之矽石玻璃。為降 134992.doc 200928605 低玻璃熱膨脹係數之目的而添加之摻雜劑的代表性實例為 Ti〇2。添加Ti〇2作為摻雜劑之石夕石玻璃的特定實例包括 ULE(註冊商標）Code 7972(由 Corning lncorporated公司製 造）。 . 在EUVL用光學元件製備中，首先，將該低膨脹玻璃或 極低膨脹玻璃之原材料切割成預定形狀及預定尺寸。隨後 加工其光學面以達到預定平面度及預定表面粗糙度。 EUVL用光學元件需要具有平滑度極佳之光學面。特定 言之，必須進行表面處理以便使所製造之表面具有不大於 50 nm之平面度及不大於5nm之表面粗糙度（Ra)。 在製造反射型光罩或鏡面時或在進行EUVL時，出現切 削EUVL用光學元件的轉角（c〇mer)之問題。為此，通常使 EUVL用光學元件之轉角經受倒角加工。 然而，即使在使轉角經受倒角加工之情況下，當將 EUVL用光學元件固定於製造裝置或曝光工具後、更特定 ❹ S之當將其用夹具或其類似物夾緊後，仍會發生切削倒角 部分之問題。 專利文獻 1 . JP-T-2003-505891 * 【發明内容】 . 為解決上述背景技術所帶有之問題，本發明之目的為提 供一種EUVL用光學元件’其係用於EUVL用反射型光罩、 鏡面等’且具有平面度及表面粗糙度極佳之光學面，且在 表層附近具有極佳強度，且其中阻止產生切削倒角。本發 明之另一目的為提供一種EUVl用光學元件之光學面的表 134992.doc 200928605 面處理方法。 為達成上述目的，本發明提供一種EUVL用光學元件之 表面處理方法，其包含用含有It及氯中之至少一者的源氣 體對EUV微影術（EUVL)用光學元件之光學面施用氣體團簇 離子束（gas cluster ion beam，GCIB)触刻，其中該光學元 件係包含具有100 ppm或100 ppm以上之OH濃度、含有 ' Ti〇2、且含有Si〇2作為主要組份之矽石玻璃材料。 在本發明之EUVL用光學元件的表面處理方法中，較佳 ® 為£1^^用光學元件具有3至10質量％之丁丨02濃度。 在本發明之EUVL用光學元件的表面處理方法中，較佳 為EUVL用光學元件在2(TC下具有0±30 ppb/°C之熱膨脹係 數。 在將用於曝光之EUV光的能量升高以提高EUVL曝光工 具之通量（throughput)的情況下，光學元件之溫度增加超出 一般假定範圍（ordinary assumption)。特定言之，光學元件 _ 之溫度可能增至40至11 0°C之溫度。在此情況下，較佳為 本發明之光學元件在40至110°C之溫度下具有0±30 ppb/°C 之熱膨脹係數，以防止用作光罩或其類似物時圖案之間距 (pitch)改變，且防止用作步進鏡面（stepper mirror)或其類 1 似物時形狀變化。 在本發明之EUVL用光學元件的表面處理方法中，較佳 為在施用GCIB蝕刻之前，EUVL用光學元件具有不大於5 nm 之表面粗链度（Ra)。 在本發明之EUVL用光學元件的表面處理方法中，較佳 134992.doc 200928605 為所用源氣體為選自由以下各混合氣體所組成之群的任一 混合氣體：SF6與02之混合氣體；SF6、Ar與02之混合氣 體；NF3與02之混合氣體；NF3、Ar與02之混合氣體；NF3 與N2之混合氣體；NF3、Ar與N2之混合氣體；Cl2與02之混 合氣體；Cl2、Ar與02之混合氣體；（：12與]^2之混合氣體； Cl2、Ar與N2之混合氣體；CF4與02之混合氣體；CF4、Ar 與02之混合氣體；CF4與N2之混合氣體；CF4、八卩與乂之混 合氣體；CH2F2與02之混合氣體；CH2F2、Ar與02之混合 氣體；（：1142與]^2之混合氣體；CH2F2、Ar與川之混合氣 體；CHF3與02之混合氣體；CHF3、Ar與02之混合氣體； CHF3與N2之混合氣體；及CHF3、Ar與N2之混合氣體。 本發明亦提供一種EUVL用光學元件，其已藉由本發明 之EUVL用光學元件的表面處理方法進行表面處理。 本發明亦提供一種EUV微影術（EUVL)用光學元件，其係 包含具有100 ppm或100 ppm以上之OH濃度及3至10質量。/〇 之Ti〇2濃度，且含有Si02作為主要組份的矽石玻璃材料， 該EUVL用光學元件具有表面粗糙度（Ra)不大於5 nm且 滿足以下表達式的光學面： (log C2〇〇nm" log C2〇nm)/(200-20) < -3.〇xlO'3 其中匸剔⑽表示在距光學面200 nm深度處氟濃度及氯濃度 之總濃度（ppm);且(^加^表示在距光學面20 nm深度處氟濃 度及氣濃度之總濃度（ppm)。 本發明亦提供一種EUV微影術（EUVL)用光學元件，其係 包含具有100 ppm或100 ppm以上之OH濃度及3至10質量％ 134992.doc -10- 200928605 之Ti02濃度、且含有Si02作為主要組份的石夕石玻璃材料， 該EUVL用光學元件具有表面粗糙度（Ra)不大於5 nm且 滿足以下表達式的光學面： C20nm~ C2〇〇nm ^ 5 ppm 其中（^。⑽表示在距光學面20 nm深度處氟濃度及氯濃度之 總濃度（ppm);且(:扇㈣表示在距光學面200 nm深度處氟濃 度及氯濃度之總濃度（ppm)。 在EUVL用光學元件中，較佳為沿光學面之外緣成倒BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical element for extreme ultraviolet (EUV) lithography and a surface treatment method for the optical surface thereof. [Prior Art] In the lithography technology towel, an exposure tool for manufacturing an integrated circuit by transferring a fine circuit pattern onto a wafer has been widely used so far. With the trend toward higher integration, high speed and high functionality, integrated circuits are being improved. Therefore, the exposure tool is required to form a circuit pattern image having a high resolution on the surface of the wafer with a long focal depth, and the wavelength of the light for exposure is being shortened. The exposure source is further improved by conventional g-ray (wavelength .436 nm), i-ray (wavelength: 365 nm) and KrF excimer laser (wavelength: 248 nm), and ArF excimer laser (wavelength: 193) Nm) will be put into use soon. In addition, in order to cope with the next-generation integrated circuit in which the circuit line width will become no more than 7〇ηπ1, both the immersion exposure technique and the double exposure technique of the ArF excimer laser will be used. Leading. However, it is believed that even these technologies will only cover a generation with a line width of up to 45 nm. Under the aforementioned technology trend, it is considered that the use of EUV light as the next generation exposure light lithography technology is suitable for 32 nm and later generations and is attracting attention. EUV light as referred to herein means light having a wavelength in a soft X-ray region or a vacuum ultraviolet region, especially having a wavelength of about 0.2 to 100 nm. Currently, a 13.5 nm lithography source is being studied. The exposure principle of this EUV lithography (hereinafter abbreviated as "EUVL") is equivalent to the exposure principle of conventional lithography using a projection optical system to transfer light 134992.doc 200928605 hood pattern. However, because there is no material that is transparent to the EUV light energy region, a refractive optical system cannot be used. Therefore, it is inevitable to use a reflection optical system (see Patent Document 1). Examples of reflective optical systems for EUVL include reflective reticle and mirrors, such as concentrating optics mirrors, illumination optics mirrors, and projection optics mirrors. The reflective mask mainly comprises (1) an optical element for EUVL (for example, a glass substrate), (2) a reflective multilayer film formed on an optical surface of an optical element for EUVL, and (3) a reflective multilayer film. The absorption layer. On the other hand, the mirror surface mainly includes (1) an optical element for EUVL (for example, a glass substrate) and (2) a reflective multilayer film formed on the optical surface of the optical element for EUVL. As the reflective multilayer film, a structure in which a plurality of materials having different refractive indices for the wavelength of exposure light are cyclically laminated to each other in a nanometer size are used. Representative examples of materials known from the Mo and Si systems. In addition, Ta and Cr have been studied as absorption layers. As the optical element for EUVL, a material having a low coefficient of thermal expansion is required in order to prevent strain even after irradiation with EUV light, and glass having a low coefficient of thermal expansion or glass-ceramic having a low coefficient of thermal expansion has been studied. In the present specification, a glass having a low coefficient of thermal expansion and a glass-ceramic having a low coefficient of thermal expansion are collectively referred to hereinafter as "low-expansion glass, or "very low-expansion glass". As such a low-expansion glass and extremely low expansion Glass, the most widely used vermiculite glass with the addition of dopants for the purpose of lowering the coefficient of thermal expansion of the glass. A representative example of a dopant added for the purpose of lowering the thermal expansion coefficient of 134992.doc 200928605 is Ti〇2. Specific examples of the Tixi 2 glass as the dopant include ULE (registered trademark) Code 7972 (manufactured by Corning Incorporated). In the preparation of the optical element for EUVL, first, the low expansion glass or the extremely low The raw material of the expanded glass is cut into a predetermined shape and a predetermined size. The optical surface is then processed to achieve a predetermined flatness and a predetermined surface roughness. The optical element for EUVL needs to have an optical surface with excellent smoothness. In particular, surface treatment must be performed. In order to make the surface produced have a flatness of not more than 50 nm and a surface roughness (Ra) of not more than 5 nm. The problem of cutting the angle of the optical element for EUVL occurs when the reticle or mirror is used or when EUVL is performed. For this reason, the corner of the optical element for EUVL is usually subjected to chamfering. In the case where the corner is subjected to chamfering, when the EUVL optical element is fixed to the manufacturing apparatus or the exposure tool, and more specifically, it is clamped by a jig or the like, the chamfering portion still occurs. Patent Document 1. JP-T-2003-505891 * SUMMARY OF THE INVENTION In order to solve the problems associated with the above background art, an object of the present invention is to provide an optical element for EUVL which is used for reflection type of EUVL. A reticle, a mirror surface, etc. and having an optical surface with excellent flatness and surface roughness, and having excellent strength in the vicinity of the surface layer, and preventing cutting chamfering therein. Another object of the present invention is to provide an optical element for EUV1 The optical surface of the table 134992.doc 200928605 Surface treatment method. In order to achieve the above object, the present invention provides a surface treatment method for an optical element for EUVL, which comprises containing It and chlorine. One of the source gases of the EUV lithography (EUVL) is coated with a gas cluster ion beam (GCIB) with an optical surface of the optical element, wherein the optical component comprises 100 ppm or more. The OH concentration, the vermiculite glass material containing 'Ti〇2 and containing Si〇2 as a main component. In the surface treatment method for the optical element for EUVL of the present invention, the optical element is preferably used for £1^^ In the surface treatment method for the optical element for EUVL of the present invention, it is preferred that the optical element for EUVL has a thermal expansion coefficient of 0 ± 30 ppb / ° C at 2 (TC). In the case where the energy of the EUV light for exposure is raised to increase the throughput of the EUVL exposure tool, the temperature of the optical element increases beyond the general assumption. In particular, the temperature of the optical component _ may increase to a temperature of 40 to 110 °C. In this case, it is preferred that the optical element of the present invention has a thermal expansion coefficient of 0 ± 30 ppb / ° C at a temperature of 40 to 110 ° C to prevent a pattern pitch (pitch) when used as a mask or the like. Change and prevent shape changes when used as a stepper mirror or its like. In the surface treatment method for the optical element for EUVL of the present invention, it is preferred that the optical element for EUVL has a surface roughness (Ra) of not more than 5 nm before the application of the GCIB etching. In the surface treatment method for the optical element for EUVL of the present invention, preferably 134992.doc 200928605 is a mixed gas selected from the group consisting of the following mixed gases: a mixed gas of SF6 and 02; SF6, Mixed gas of Ar and 02; mixed gas of NF3 and 02; mixed gas of NF3, Ar and 02; mixed gas of NF3 and N2; mixed gas of NF3, Ar and N2; mixed gas of Cl2 and 02; Cl2, Ar and 02 mixed gas; (: 12 and ^ 2 mixed gas; Cl2, mixed gas of Ar and N2; mixed gas of CF4 and 02; CF4, mixed gas of Ar and 02; mixed gas of CF4 and N2; CF4, Mixed gas of gossip and bismuth; mixed gas of CH2F2 and 02; mixed gas of CH2F2, Ar and 02; mixed gas of (1142 and ]2; mixed gas of CH2F2, Ar and Sichuan; mixed gas of CHF3 and 02 CHF3, a mixed gas of Ar and 02; a mixed gas of CHF3 and N2; and a mixed gas of CHF3, Ar and N2. The present invention also provides an optical element for EUVL which has been surface-treated by the optical element for EUVL of the present invention. Method for surface treatment. The invention also mentions An optical component for EUV lithography (EUVL) comprising a fluorite glass having an OH concentration of 100 ppm or more and a Ti〇2 concentration of 3 to 10 mass%, and containing SiO 2 as a main component Material, the optical element for EUVL has an optical surface having a surface roughness (Ra) of not more than 5 nm and satisfying the following expression: (log C2 〇〇 nm " log C2 〇 nm) / (200-20) < -3. 〇xlO'3 where 匸 (10) indicates the total concentration (ppm) of fluorine concentration and chlorine concentration at a depth of 200 nm from the optical surface; and (^ plus ^ indicates the total fluorine concentration and gas concentration at a depth of 20 nm from the optical surface Concentration (ppm). The present invention also provides an optical element for EUV lithography (EUVL) comprising OH concentration of 100 ppm or more and 3 to 10% by mass of 134992.doc -10- 200928605 And the SiO quartz glass material containing SiO 2 as a main component, the optical element for EUVL having an optical surface having a surface roughness (Ra) of not more than 5 nm and satisfying the following expression: C20nm~C2〇〇nm^5 ppm (^. (10) indicates the total concentration (ppm) of fluorine concentration and chlorine concentration at a depth of 20 nm from the optical surface; (: Inverted fan (iv) represented by the optical element, preferably along the outside edge of the optical surface to be away from the optical surface and the fluorine concentration at a depth of 200 nm the total concentration of chlorine concentration (ppm) in the EUVL.
本發明之EUVL用光學元件在其光學面上具有極佳平面 度及表面粗糙度，且適宜用作EUVL用反射型光罩、鏡面 等。此外，本發明之EUVL用光學元件在光學面側之表層 附近具有增強之強度。因此，阻止在製造反射型光罩或鏡 面時或在進行EUVL時，產生EUVL用光學元件之切削轉 角，或阻止在轉角已經受倒角加工之情況下，產生切削倒 角。 本發明之EUVL用光學元件適宜藉由使用本發明之EUVL 用光學元件之處理方法獲得。 【實施方式】 在本發明之EUVL用光學元件之表面處理方法中，用含 有氟及氯中之至少一者的源氣體對EUVL用光學元件之光 學面施用GCIB蝕刻，該光學元件係包含具有100 ppm或 100 ppm以上之OH濃度、含有Ti〇2、且含有Si〇2作為主要 組份之碎石玻璃材料。 134992.doc 200928605 本文所提及之EUVL用光學元件的光學面係指在藉由使 用EUVL用光學元件製造反射型光罩、鏡面或其類似物中 形成有反射性多層薄膜之表面。為達到在製造反射型光罩 或鏡面時或在進行EUVL時防止切削發生之目的，通常使 EUVL用光學元件之光學面外緣之轉角經受倒角加工。 為達到降低熱膨脹係數之目的，構成EUVL用光學元件 之矽石玻璃材料含有Ti02作為摻雜劑。 儘管矽石玻璃材料中之Ti02濃度只要能使矽石玻璃材料 之熱膨脹係數足夠低以用作EUVL用光學元件外，無特別 限制，但其較佳為3至10質量％。當Ti02濃度在上述範圍内 時，矽石玻璃材料之熱膨脹係數變得足夠低。特定言之， 所得玻璃為在20°C下具有0±30 ppb/°C之熱膨脹係數的低膨 脹玻璃，且較佳為在20°C下具有〇±1〇 ppb/°C之熱膨脹係數 的極低膨脹玻璃。 以上述濃度添加Ti02作為摻雜劑之低膨脹玻璃及極低膨 脹玻璃之特定實例包括ULE(註冊商標）Code 7972(由 Corning Incorporated製造）〇 構成EUVL用光學元件之矽石玻璃材料除Si02及Ti02之 外還含有100 ppm或100 ppm以上之OH。添加OH可加速玻 璃之結構弛豫（structural relaxation)且便於實現具有低假想 溫度（fictive temperature)之玻璃結構。降低玻璃之假想溫 度可最小化熱膨脹係數之溫度相依性（temperature dependence)， 且該矽石玻璃材料適宜作為EUVL用光學元件。 此外，在矽石玻璃材料含有OH之情況下，用含有氟及 134992.doc -12· 200928605 氯中之至少一者的源氣體對EUVL用光學元件之光學面施 用GCIB蝕刻時，與在不存在OH之情況下相比，將氟或氯 併入光學元件之表層附近之更深部分。因此，在本發明之 EUVL用光學元件之表面處理方法中，有利地展現藉由用 含有氟及氯中之至少一者的源氣體對EUVL用光學元件之 光學面施用GCIB蝕刻所產生之效應。 在本發明之EUVL用光學元件之表面處理方法中，藉由 用含有氟及氯中之至少一者的源氣體對EUVL用光學元件 之光學面施用GCIB蝕刻所產生之效應如下。 如本文所提及之GCIB蝕刻為一種包含以下步驟之方 法：經由膨脹型噴嘴將處於加壓狀態的反應性物質（源氣 體）（其在常溫及常壓下為氣態）喷射至真空裝置中以形成氣 體團镇，使該氣體團鎮經受電子韓照（electronic irradiation) 以供電離，及用所得電離之GCIB輻照目標，藉此蝕刻目 標。氣體團簇係由通常包含數千個原子或分子之大量原子 團或分子團構成。在本發明之EUVL用光學元件的表面處 理方法中，當將GCIB蝕刻施用於EUVL用光學元件的光學 面時，用氣體團簇碰撞光學面因與固體之相互作用而產生 多體衝擊效應（multibody impact effect)，藉此拋光光學面 且改良平面度（第一效應）。 在本發明之EUVL用光學元件的表面處理方法中，當用 含有至少一種氟及氯之源氣體對EUVL用光學元件之光學 面施用GCIB蝕刻時，將氟或氯併入EUVL用光學元件之光 學面側的表層附近，特定言之併入矽石玻璃材料中至距 134992.doc -13- 200928605 EUVL用光學元件之光學面約loo nm之深度。在併入氟或 氯之光學面側的表層附近’可形成壓應力層（c〇mpressi〇n stress layer)。藉此，增強FUVL用光學元件之表層附近的 強度。因此，防止在製造反射型光罩或鏡面時或在進行 EUVL時產生FUVL用光學元件的切削倒角（第二效應）。 為更有效展現第二效應，較佳將GCIB蝕刻施用於整個 光學面’包括光學面之外緣的轉角或轉角處所成之倒角部 分。 為更有效展現由GCIB|虫刻所產生之效應、尤其上述第 二效應，構成EUVL用光學元件之矽石玻璃材料較佳含有 200 ppm或200 ppm以上且更佳500 ppm或500 ppm以上之量 的OH。 在本發明之EUVL用光學元件的表面處理方法中，較佳 將施用GCIB蚀刻之光學面初步拋光以便具有預定平面度 及預定表面粗链度。 0 初步拋光方法無特別限制且可廣泛選自用於拋光矽石玻 璃材料之表面的已知拋光方法。然而，因為使用具有高拋 光率及大表面積之拋光塾一次可拋光加工較大表面，故通 常使用機械拋光方法。除僅藉由研磨粒之拋光功能的拋光 加工外’本文提及之機械拋光方法還包括使用拋光衆料以 組合利用研磨粒之拋光功能及化學製品之化學拋光功能的 方法。機械拋光可為研磨及拋光之任一者。可在已知材料 中適當選擇待使用之拋光工具及研磨材料。在使用機械拋 光方法之情況下’為使加工速率高’研磨較佳在3〇至7〇 gf/cm2 134992.doc -14- 200928605 之表面壓力下且更佳在40至60 gf/cm2之表面壓力下進行； 而拋光較佳在60至140 gf/cm2之表面壓力下且更佳在80至 120 gf/cm2之表面壓力下進行。關於拋光量，研磨較佳以 100至300 μπι之拋光量進行；而拋光較佳以1至60 μπι之拋光 量進行。 在進行初步拋光之情況下，在初步拋光之後光學面之表 面粗韓:度（Ra)較佳不大於5 nm、更佳不大於3 nm且進一步 較佳不大於1 nm。本說明書中提及之表面粗链度（Ra)意謂 藉由原子力顯微鏡針對1至10 μηι2之面積所量測的表面粗 糙度。當在初步拋光之後光學面上之表面粗糙度超過5 nm 時，在本發明之EUVL用光學元件的表面處理方法中需要 花費大量時間藉由施用GCIB蝕刻調節光學面以得到預定 平面度及預定表面粗糙度，從而使成本增加。 當含有至少氟及氣之源氣體用於GCIB蝕刻時，較佳使 用選自以下混合氣體之任何一種混合氣體：SF6與02之混 合氣體；SF6、Ar與02之混合氣體；NF3與02之混合氣 體；NF3、Ar與02之混合氣體；NF3與N2之混合氣體； NF3、Ar與N2之混合氣體；Cl2與02之混合氣體；Cl2、Ar 與02之混合氣體；Cl2與N2之混合氣體；Cl2、Ar與N2之混 合氣體；CF4與02之混合氣體；CF4、Ar與02之混合氣體； 匸？4與N2之混合氣體；CF4、八1*與N2之混合氣體；CH2F2與 02之混合氣體；CH2F2、Ar與02之混合氣體；（：1^2與N2 之混合氣體；CH2F2、Ar與N2之混合氣體；CHF3與02之混 合氣體；CHF3、Ar與02之混合氣體；CHF3與N2之混合氣 134992.doc -15- 200928605 體；及CHF3、Ar與N2之混合氣體。 在該等混合氣體中，儘管個別組份之合適混合比視輻照 條件及其類似因素而改變，但以下為較佳。 SF6:O2=(0· 1 至 5%)··(95至 99.9%)(SF6與 02之混合氣體） SF6:Ar.O2=(0.1 至 5%):(9.9 至 49·9%)··(50 至 90%)(SF6、Ar 與02之混合氣體） NF3:O2=(0.1 至 5%):(95至 99.9%)(NF3與 02之混合氣體） NF3:Ar:O2=(0.1 至 5%):(9.9至 49·9°/〇):(50 至 90%)(NF3、Ar 與〇2之混合氣體） NF3:N2=(0.1 至 5%):(95 至 99.9%)”？3與 N2之混合氣體） NF3:Ar:N2=(0.1 至 5%):(9.9 至 49.9%):(50 至 90%)(NF3、Ar 與N2之混合氣體）The optical element for EUVL of the present invention has excellent flatness and surface roughness on its optical surface, and is suitably used as a reflective mask, mirror surface or the like for EUVL. Further, the optical element for EUVL of the present invention has an enhanced strength in the vicinity of the surface layer on the optical surface side. Therefore, it is prevented that the cutting angle of the optical element for EUVL is generated at the time of manufacturing the reflective reticle or the mirror or when the EUVL is performed, or the cutting chamfer is prevented from being generated when the corner has been subjected to chamfering. The optical element for EUVL of the present invention is suitably obtained by using the treatment method of the optical element for EUVL of the present invention. [Embodiment] In the surface treatment method for an optical element for EUVL of the present invention, a GCBI etching is applied to an optical surface of an optical element for EUVL using a source gas containing at least one of fluorine and chlorine, the optical element comprising 100 An OH concentration of ppm or more of 100 ppm or more, a gravel glass material containing Ti〇2 and containing Si〇2 as a main component. 134992.doc 200928605 The optical surface of the optical element for EUVL referred to herein refers to a surface on which a reflective multilayer film is formed by using an optical element for EUVL to manufacture a reflective mask, a mirror surface or the like. In order to achieve the purpose of preventing the occurrence of cutting during the manufacture of the reflective reticle or mirror or during the EUVL, the corners of the outer edge of the optical surface of the optical element for EUVL are usually subjected to chamfering. In order to achieve a reduction in thermal expansion coefficient, the vermiculite glass material constituting the optical element for EUVL contains TiO 2 as a dopant. The TiO2 concentration in the vermiculite glass material is not particularly limited as long as the coefficient of thermal expansion of the vermiculite glass material is sufficiently low to be used as the optical element for EUVL, but it is preferably from 3 to 10% by mass. When the TiO 2 concentration is within the above range, the thermal expansion coefficient of the vermiculite glass material becomes sufficiently low. Specifically, the obtained glass is a low expansion glass having a thermal expansion coefficient of 0 ± 30 ppb / ° C at 20 ° C, and preferably has a thermal expansion coefficient of 〇 ± 1 〇 ppb / ° C at 20 ° C Very low expansion glass. Specific examples of the low-expansion glass and the extremely low-expansion glass in which TiO 2 is added as a dopant at the above concentration include ULE (registered trademark) Code 7972 (manufactured by Corning Incorporated) 矽 矽 〇 〇 EU EU EU EU EU EU EU EU EU EU EU EU EU EU It also contains 100 ppm or more of OH. The addition of OH accelerates the structural relaxation of the glass and facilitates the realization of a glass structure having a low fictive temperature. Reducing the hypothetical temperature of the glass minimizes the temperature dependence of the coefficient of thermal expansion, and the vermiculite glass material is suitable as an optical element for EUVL. Further, in the case where the vermiculite glass material contains OH, when the GCIB etching is applied to the optical surface of the optical element for EUVL using a source gas containing at least one of fluorine and 134992.doc -12·200928605 chlorine, In the case of OH, fluorine or chlorine is incorporated into a deeper portion near the surface layer of the optical element. Therefore, in the surface treatment method for the optical element for EUVL of the present invention, the effect produced by applying the GCIB etching to the optical surface of the optical element for EUVL by using the source gas containing at least one of fluorine and chlorine is advantageously exhibited. In the surface treatment method for an optical element for EUVL of the present invention, the effect of applying GCIB etching to the optical surface of the optical element for EUVL by using a source gas containing at least one of fluorine and chlorine is as follows. The GCIB etching as referred to herein is a method comprising the steps of: injecting a reactive substance (source gas) in a pressurized state (which is gaseous at normal temperature and normal pressure) into a vacuum device via an expansion nozzle A gas cluster is formed, the gas cluster is subjected to electronic irradiation to supply power, and the target is irradiated with the obtained ionized GCIB, thereby etching the target. A gas cluster is composed of a large number of atomic groups or molecular groups usually containing thousands of atoms or molecules. In the surface treatment method for the optical element for EUVL of the present invention, when GCIB etching is applied to the optical surface of the optical element for EUVL, the collision of the optical surface with the gas cluster causes a multibody impact effect due to interaction with the solid (multibody) Impact effect), thereby polishing the optical surface and improving the flatness (first effect). In the surface treatment method for the optical element for EUVL of the present invention, when a GCIB etching is applied to the optical surface of the optical element for EUVL using a source gas containing at least one fluorine and chlorine, fluorine or chlorine is incorporated into the optical element for the optical element for EUVL. Near the surface of the face side, specifically into the vermiculite glass material to the depth of the optical surface of the 134992.doc -13- 200928605 EUVL optical element about loo nm. A compressive stress layer may be formed in the vicinity of the surface layer on the side of the optical surface to which fluorine or chlorine is incorporated. Thereby, the strength in the vicinity of the surface layer of the optical element for FUVL is enhanced. Therefore, it is prevented that the chamfering (second effect) of the optical element for FUVL is generated when the reflective mask or mirror is manufactured or when EUVL is performed. In order to more effectively exhibit the second effect, the GCIB etching is preferably applied to the entire optical surface 'including the chamfered portion formed at the corner or corner of the outer edge of the optical surface. In order to more effectively exhibit the effect produced by GCIB|Insect, especially the second effect described above, the vermiculite glass material constituting the optical element for EUVL preferably contains 200 ppm or more and more preferably 500 ppm or more. OH. In the surface treatment method for the optical element for EUVL of the present invention, it is preferred to initially polish the optical surface to which the GCIB etching is applied so as to have a predetermined flatness and a predetermined surface thick chain. The preliminary polishing method is not particularly limited and can be widely selected from known polishing methods for polishing the surface of a vermiculite glass material. However, since a polishing surface having a high polishing rate and a large surface area can be used to polish a large surface at a time, a mechanical polishing method is usually used. In addition to the polishing process by the polishing function of the abrasive particles, the mechanical polishing method mentioned herein also includes a method of using a polishing mass to combine the polishing function of the abrasive particles and the chemical polishing function of the chemical. Mechanical polishing can be either polishing or polishing. The polishing tool and the abrasive material to be used can be appropriately selected among known materials. In the case of using a mechanical polishing method, 'for high processing rate' grinding is preferably at a surface pressure of 3 〇 to 7 〇 gf/cm 2 134992.doc -14 - 200928605 and more preferably at a surface of 40 to 60 gf/cm 2 The polishing is preferably carried out under pressure at a surface pressure of 60 to 140 gf/cm 2 and more preferably at a surface pressure of 80 to 120 gf/cm 2 . Regarding the amount of polishing, the polishing is preferably carried out at a polishing amount of from 100 to 300 μm; and the polishing is preferably carried out at a polishing amount of from 1 to 60 μm. In the case of preliminary polishing, the surface of the optical surface after the preliminary polishing is preferably not more than 5 nm, more preferably not more than 3 nm and further preferably not more than 1 nm. The surface roughness (Ra) mentioned in the specification means the surface roughness measured by an atomic force microscope for an area of 1 to 10 μm 2 . When the surface roughness of the optical surface exceeds 5 nm after the preliminary polishing, it takes a lot of time in the surface treatment method of the optical element for EUVL of the present invention to adjust the optical surface by applying the GCIB etching to obtain a predetermined flatness and a predetermined surface. Roughness, which increases costs. When a source gas containing at least fluorine and gas is used for the GCIB etching, it is preferred to use any mixed gas selected from the group consisting of a mixed gas of SF6 and 02; a mixed gas of SF6, Ar and 02; and a mixture of NF3 and 02. Gas; NF3, mixed gas of Ar and 02; mixed gas of NF3 and N2; NF3, mixed gas of Ar and N2; mixed gas of Cl2 and 02; mixed gas of Cl2, Ar and 02; mixed gas of Cl2 and N2; Cl2, a mixed gas of Ar and N2; a mixed gas of CF4 and 02; a mixed gas of CF4, Ar and 02; a mixed gas of 4 and N2; a mixed gas of CF4, VIII1 and N2; a mixed gas of CH2F2 and 02; a mixed gas of CH2F2, Ar and 02; (a mixed gas of 1^2 and N2; CH2F2, Ar and N2) a mixed gas; a mixed gas of CHF3 and 02; a mixed gas of CHF3, Ar and 02; a mixture of CHF3 and N2 134992.doc -15- 200928605; and a mixed gas of CHF3, Ar and N2. In the above, although the appropriate mixing of the individual components is changed depending on the irradiation conditions and the like, the following is preferable. SF6: O2 = (0·1 to 5%)··(95 to 99.9%) (SF6 and 02 mixed gas) SF6: Ar.O2 = (0.1 to 5%): (9.9 to 49.9%) · (50 to 90%) (SF6, mixed gas of Ar and 02) NF3: O2 = (0.1 To 5%): (95 to 99.9%) (mixture of NF3 and 02) NF3: Ar: O2 = (0.1 to 5%): (9.9 to 49·9 ° / 〇): (50 to 90%) ( NF3, a mixture of Ar and 〇2) NF3: N2 = (0.1 to 5%): (95 to 99.9%) "? 3 and N2 mixed gas) NF3: Ar: N2 = (0.1 to 5%): ( 9.9 to 49.9%): (50 to 90%) (NF3, a mixture of Ar and N2)
Cl2:O2=(0.1 至 5%):(95 至 99.9%)(C12與 02之混合氣體） Cl2:Ar:O2=(0.1 至 5%):(9.9 至 49.9%):(50 至 90%)(C12、Ar 與〇2之混合氣體） C12:N2=(0.1 至 5%):(95 至 99.9%)(C12與 N2之混合氣體） Cl2:Ar:N2=(0·l至5o/o):(9.9至49.9%):(5 0至90%)(Cl2、Ar 與乂之混合氣體） CF4:O2 = (0.1 至 5%):(95 至 99.9%)(CF4與 02之混合氣體） CF4:Ar:O2=(0.1 至 5%):(9.9 至 49.9%):(50 至 90%)(CF4、Ar 與〇2之混合氣體） CF4:N2=(0· 1 至 5%):(95 至 99.9%)(CF4與 N2之混合氣體） CF4:Ar:N2=(0.1 至 5%):(9.9 至 49.9%):(50 至 90%)(CF4、Ar 與N2之混合氣體） 134992.doc -16- 200928605 CH2F2:O2=(0.1 至 5%)··(95 至 99.9%)(CH2F2 與 02 之混合氣 體） CH2F2:Ar:O2=(0.1 至 5%):(9.9至 49.9%):(50至 90%)(CH2F2、Ar 與〇2之混合氣體） CH2F2:N2=(0.1 至 5%):(95 至 99.9%)(CH2F2 與 乂之混合氣 體） CH2F2:Ar:N2=(0.1 至 5%):(9.9 至 49·9%):(50 至 90%)(CH2F2、 Ar與N2之混合氣體） CHF3:O2=(0.1 至 5%):(95至 99.9%)(CHF3與 〇2之混合氣體） CHF3:Ar:O2 = (0.1 至 5%):(9.9至 49.9%):(50至 90%)(CHF3、 Ar與02之混合氣體） CHF3 :N2=(0. 1 至 5°/。）:（95 至 99.9%)(CHF3與 N2之混合氣體） CHF3:Ar:N2 = (0.1 至 5%):(9.9至 49.9%):(50至 90%)(CHF3、 Ar與N2之混合氣體） 可視源氣體之種類及光學面之表面特性而定適當選擇輻 照條件，包括團簇尺寸、施用於GCIB蝕刻裝置以電離團 簇之電離電極的電離電流、施用於GCIB蝕刻裝置之加速 電極的加速電壓及GCIB用量。舉例而言，為改良平面度 而不使光學面之表面粗糙度過度退化，施用於加速電極之 加速電壓較佳為15至30 kV。 在進行GCIB蝕刻時，必須用GCIB掃描光學面。作為 GCIB掃描方法，已知光柵掃描（raster scanning)及螺旋掃 描（spiral scanning)，且可使用該等方法中之任一者。 在已經受藉由本發明之EUVL用光學元件之表面處理方 134992.doc 17 200928605 法表面處理之EUVL用光學元件（下文稱為"本發明之EUVL 用光學元件"）中，因為將氟或氣併入藉由GCIB蝕刻所加工 之光學面，故EUVL用光學元件之表層附近的氟濃度或氯 濃度變得高於EUVL用光學元件之較深部分。 本發明之EIJVL·用光學元件較佳滿足以下表達式。 (l〇g C2〇〇nm-l°g C2〇nm)/(2〇〇-20) < -3.0><10 3 此處，（^⑽㈣表示在距光學面200 nm深度處氟濃度及氯 濃度之總濃度（ppm) 1 且 C2〇nm 表示在距光學面20 nm深度處 氟濃度及氯濃度之總濃度（ppm)。 (log C2〇〇nm-l〇g C2〇nm)/(20〇-20)之值為對應於光學元件 中，自該光學元件之表層附近至該光學元件之較深部分的 氟濃度及氯濃度之總濃度梯度之值。此值更佳小於-8.0XHT3 且進一步較佳小於-lo.oxicr3。 本發明之EUVL·用光學元件較佳滿足以下表達式。 C 2 0 n m - C 2 〇 〇 n m 2 5 ρ ρ Π1 (C2〇nm-C2()()nm)之值為對應於光學元件中，自該光學元件 之表層附近至該光學元件之較深部分的氟濃度及氯濃度之 總濃度梯度之值。此值更佳為10 ppm或10 ppm以上且進一 步較佳為1 5 ppm或1 5 ppm以上。 本發明之EUVL用光學元件在光學面上具有極佳平面度 及表面粗糙度。特定言之，光學面之平面度較佳不大於 100 nm、更佳不大於50 nm且進一步較佳不大於30 nm。此 外，光學面之表面粗梭度Ra較佳不大於5 nm、更佳不大於 3 nm且進一步較佳不大於1 nm。 134992.doc -18- 200928605 因為在表層附近形成 光學面較佳具有50 g 且進—步較佳200 g或 在本發明之EUVL用光學元件中， 壓應力層，故增強表層附近之強度。 或50 g以上、更佳1〇〇 g或1〇〇 g以上 2〇〇 g以上之裂縫起始載荷。Cl2: O2 = (0.1 to 5%): (95 to 99.9%) (mixture of C12 and 02) Cl2: Ar: O2 = (0.1 to 5%): (9.9 to 49.9%): (50 to 90%) (C12, mixed gas of Ar and 〇2) C12: N2 = (0.1 to 5%): (95 to 99.9%) (mixture of C12 and N2) Cl2: Ar: N2 = (0·l to 5o/ o): (9.9 to 49.9%): (50 to 90%) (mixture of Cl2, Ar and yttrium) CF4: O2 = (0.1 to 5%): (95 to 99.9%) (mixture of CF4 and 02) Gas) CF4: Ar: O2 = (0.1 to 5%): (9.9 to 49.9%): (50 to 90%) (CF4, a mixed gas of Ar and 〇2) CF4: N2 = (0·1 to 5%) ): (95 to 99.9%) (mixture of CF4 and N2) CF4: Ar: N2 = (0.1 to 5%): (9.9 to 49.9%): (50 to 90%) (mixture of CF4, Ar and N2) Gas) 134992.doc -16- 200928605 CH2F2:O2=(0.1 to 5%)··(95 to 99.9%) (mixture of CH2F2 and 02) CH2F2: Ar:O2=(0.1 to 5%): (9.9 To 49.9%): (50 to 90%) (CH2F2, a mixture of Ar and 〇2) CH2F2: N2 = (0.1 to 5%): (95 to 99.9%) (mixture of CH2F2 and ruthenium) CH2F2: Ar : N2 = (0.1 to 5%): (9.9 to 49.9%): (50 to 90%) (CH2F2, a mixture of Ar and N2) CHF3: O2 = (0.1 to 5%): (95 to 99.9) %)(Combination of CHF3 and 〇2 Combined gas) CHF3: Ar: O2 = (0.1 to 5%): (9.9 to 49.9%): (50 to 90%) (CHF3, mixed gas of Ar and 02) CHF3: N2 = (0.1 to 5°) /.): (95 to 99.9%) (mixture of CHF3 and N2) CHF3: Ar: N2 = (0.1 to 5%): (9.9 to 49.9%): (50 to 90%) (CHF3, Ar and N2) Mixed gas) The irradiation conditions are appropriately selected depending on the kind of the source gas and the surface characteristics of the optical surface, including the cluster size, the ionization current applied to the ionizing electrode of the ionizing cluster applied to the GCIB etching apparatus, and applied to the GCIB etching apparatus. Accelerate the accelerating voltage of the electrode and the amount of GCIB. For example, in order to improve the flatness without excessively deteriorating the surface roughness of the optical surface, the acceleration voltage applied to the accelerating electrode is preferably 15 to 30 kV. When performing a GCIB etch, the optical surface must be scanned with GCIB. As the GCIB scanning method, raster scanning and spiral scanning are known, and any of these methods can be used. In the optical element for EUVL (hereinafter referred to as "the optical element for EUVL" of the present invention) which has been subjected to surface treatment by the surface treatment of the optical element for EUVL of the present invention (hereinafter referred to as "the optical element for EUVL" of the present invention), Since the gas is incorporated into the optical surface processed by the GCIB etching, the fluorine concentration or the chlorine concentration in the vicinity of the surface layer of the optical element for EUVL becomes higher than the deep portion of the optical element for EUVL. The EIJVL optical element of the present invention preferably satisfies the following expression. (l〇g C2〇〇nm-l°g C2〇nm)/(2〇〇-20) <-3.0><10 3 Here, (^(10)(4) represents fluorine at a depth of 200 nm from the optical surface The total concentration (ppm) of concentration and chlorine concentration 1 and C2〇nm represents the total concentration (ppm) of fluorine concentration and chlorine concentration at a depth of 20 nm from the optical surface (log C2〇〇nm-l〇g C2〇nm) The value of /(20〇-20) corresponds to the value of the total concentration gradient of the fluorine concentration and the chlorine concentration from the vicinity of the surface layer of the optical element to the deeper portion of the optical element in the optical element. This value is better than - 8.0XHT3 and further preferably less than -lo.oxicr3. The EUVL optical element of the present invention preferably satisfies the following expression: C 2 0 nm - C 2 〇〇nm 2 5 ρ ρ Π1 (C2〇nm-C2() The value of () nm) corresponds to the value of the total concentration gradient of the fluorine concentration and the chlorine concentration from the vicinity of the surface layer of the optical element to the deep portion of the optical element in the optical element. The value is preferably 10 ppm or 10 More than ppm and further preferably 15 ppm or more than 15 ppm. The optical element for EUVL of the present invention has excellent flatness and surface roughness on an optical surface. Specifically, an optical surface The surface is preferably not more than 100 nm, more preferably not more than 50 nm, and further preferably not more than 30 nm. Further, the surface roughness Ra of the optical surface is preferably not more than 5 nm, more preferably not more than 3 nm, and further Preferably, it is not more than 1 nm. 134992.doc -18- 200928605 Since the optical surface is preferably formed in the vicinity of the surface layer, preferably 50 g and preferably 200 g in advance, or in the optical element for EUVL of the present invention, the compressive stress layer is enhanced. Strength near the surface layer. Or crack starting load of 50 g or more, more preferably 1 〇〇 g or more than 1 〇〇 g and more than 2 〇〇 g.
裂縫起始載荷以以下方式量測。亦即，在藉由維氏 (Vickers)硬度_量測設備用維氏壓頭壓印15秒之後，移除維 氏壓頭且觀察壓痕附近。將該面積分成4個區$，以連接 壓痕之中心、及轉角的線作為邊界，且藉由檢測在個別區域 是否產生裂縫而評估裂縫產生之機率。僅在4個區域中之 一者中發現裂縫之情沉表示為25%;僅在2個區域中發現 裂縫之情況表示為50% ;僅在3個區域中發現裂縫之情況 表示為75% ;且在所有4個區域中發現裂縫之情況表示為 1〇〇°/。。藉由量測複數個樣品，確定裂縫產生之機率。將 裂縫產生之機率為1〇0%之最小載荷視為裂縫起始载荷。 實例 本發明參考以下實例進行更詳細的說明，但不應將本發 明視為限制於此。實例丨為本發明之實例且實例2為比較實 例0 實例1 在初步拋光矽石玻璃材料基板（OH濃度：88〇 ppm，Tih ί辰度.7·0質量％，尺寸：2〇 mmx20 mmxl.5 mm-厚度）之 後，將GCIB蝕刻施用於基板表面。初步拋光及gcib蝕刻 之條件如下所示。 <初步拋光之條件> i34992.doc -19- 200928605 拋光種類：機械拋光 表面壓力：100 g/cm2。 <GCIB|虫刻之條件> 源氣體·· SFAN2之混合氣體（SF6:N2=5%:95%) 加速電壓：24 kV 團簇尺寸：3,000 射束電流：1 0 0 u m 實例2 使與實例1中相同之矽石玻璃材料基板僅經受初步拋 光。 使用一次電離質譜儀（secondary ionization mass spectrometer， SIMS)量測實例1及2各自的石英玻璃材料基板中沿距基板 表面之深度方向的氟濃度。結果如圖丨所示。 由圖1明顯可見，證實在已經受GCIB蝕刻之實例1的基 板中，在距表面深達100 11111處之表層附近的氟濃度藉由併 ❹ 入氟而變高。甚至在未經受GCIB蝕刻之實例2基板中表面 區域之氟濃度較高的原因在於，在量測氟濃度之前將基板 表面用氫氟酸洗滌。 製備10個實例1及2各自之矽石玻璃材料基板薄片，且將 * 1 00 8之維氏壓頭壓印於基板表面上15秒以評估抗裂性。 證實對於實例1之玻璃’在所有1〇個薄片中未產生裂 縫，而對於實例2之玻璃，在所有丨〇個薄片中均產生裂 縫。由此’可證實因GCIB蝕刻而阻止切削產生的效應。 儘管已詳細且參考特定實施例描述本發明，但熟習此項 134992.doc .20- 200928605 技術者將易瞭解，可在不背離本發明之精神及 下進行各種改變及修飾。 範嗜的情況 第 本申請案係基於細7年12月27日申請之日本專利申 2〇〇7_336167號且其内容以引用的方式併人本文中〇 【圖式簡單說明】 請案 圖1為顯示沿距基板表 面之深度方向的氟濃度圖 〇The crack initiation load is measured in the following manner. That is, after imprinting with a Vickers indenter for 15 seconds by a Vickers hardness measuring device, the Vickers indenter was removed and the vicinity of the indentation was observed. The area is divided into four areas $ to connect the center of the indentation and the line of the corner as a boundary, and the probability of occurrence of the crack is evaluated by detecting whether or not cracks are generated in the individual areas. The crack of the crack was found to be 25% in only one of the four regions; the case where the crack was found only in the two regions was expressed as 50%; the case where the crack was found only in the three regions was expressed as 75%; The case where cracks were found in all four regions was expressed as 1 〇〇 ° /. . The probability of crack generation is determined by measuring a plurality of samples. The minimum load at which the probability of crack generation is 1〇0% is regarded as the crack initiation load. EXAMPLES The present invention is explained in more detail with reference to the following examples, but the invention should not be construed as being limited thereto. Example 丨 is an example of the present invention and Example 2 is a comparative example 0 Example 1 In the preliminary polishing of a vermiculite glass substrate (OH concentration: 88 〇 ppm, Tih ί 度. 7.9 mass%, size: 2 〇 mm x 20 mm x l. After 5 mm-thickness, a GCIB etch is applied to the surface of the substrate. The conditions for preliminary polishing and gcib etching are as follows. <Preliminary polishing conditions> i34992.doc -19- 200928605 Polishing type: mechanical polishing Surface pressure: 100 g/cm2. <GCIB|Insect condition> Source gas·· SFAN2 mixed gas (SF6: N2 = 5%: 95%) Accelerating voltage: 24 kV Cluster size: 3,000 Beam current: 1 0 0 um Example 2 The same vermiculite glass material substrate as in Example 1 was only subjected to preliminary polishing. The concentration of fluorine in the depth direction from the surface of the substrate in each of the quartz glass material substrates of Examples 1 and 2 was measured using a secondary ionization mass spectrometer (SIMS). The results are shown in Figure 。. As is apparent from Fig. 1, it was confirmed that in the substrate of Example 1 which had been subjected to GCIB etching, the fluorine concentration in the vicinity of the surface layer at a depth of 100 11111 from the surface became high by the incorporation of fluorine. The reason why the fluorine concentration in the surface region of the substrate of Example 2 which was not etched by GCIB was higher was that the surface of the substrate was washed with hydrofluoric acid before measuring the fluorine concentration. Ten sheets of the vermiculite glass substrate sheets of each of Examples 1 and 2 were prepared, and a Vickers indenter of *100 was imprinted on the surface of the substrate for 15 seconds to evaluate crack resistance. It was confirmed that the glass of Example 1 did not cause cracks in all of the sheets, and for the glass of Example 2, cracks were generated in all of the sheets. Thus, the effect of cutting by the GCIB etching can be confirmed. Although the present invention has been described in detail and with reference to the specific embodiments thereof, it will be understood that The case of Fan's application is based on the Japanese Patent Application No. 2〇〇7_336167 filed on Dec. 27, 2007, the contents of which are hereby incorporated by reference. Displaying the fluorine concentration pattern along the depth direction from the surface of the substrate〇
134992.doc •21 ·134992.doc •21 ·