200933691 九、發明說明 【發明所屬之技術領域】 本發明係關於一種用以進行藉由紫外線的樹脂硬化、 半導體基板或玻璃基板等之表面洗淨、殺菌、光化學反應 等之紫外線放射所使用的放電燈，尤其係關於一種利用介 電質屏障放電’獲得稀有氣體與氟之準分子發光的準分子 放電燈。 ❹ 【先前技術】 已封入稀有氣體與鹵素的準分子放電燈係具有與高壓 水銀燈或金屬鹵素燈等其他燈完全不同的放射特性，尤其 ’可高效率地發生在高壓水銀燈或金屬鹵素燈等燈中所無 法獲得的波長的紫外線。 準分子放電燈係可藉由組合所封入的稀有氣體與鹵素 ，來選擇所放射紫外線的波長。例如，在氬（Ar)與氟（ φ F)之組合中可獲得193nm附近的紫外線，在氪（Kr)與 氟（F)的組合中，可獲得248 nm附近的紫外線，在氤（ Xe)與氟（F)的組合中，可獲得351nm附近的紫外線。 尤其，在半導體的光微影法所使用之獲得193 nrn之波長的 紫外線的ArF準分子放電燈、或獲得24 8nm之波長之紫外 線的KrF準分子放電燈中，係可利用在光阻的特性試驗、 光罩的檢査等。 在專利文獻1中係揭示一種利用金屬氧化物之不活性 化層被覆由石英玻璃所構成的放電容器的內面，在放電容 -4 - 200933691 器內封入稀有氣體與齒素的準分子放電燈。其已記載當將 作爲鹵素的氟或氯封入石英玻璃製放電容器而使用時，鹵 素原子及離子立即與石英玻璃反應，產生鹵化矽及氧，而 變得未進行準分子放電，因此必須被覆石英玻璃內面。 此外，在專利文獻2中係揭示一種將稀有氣體與鹵素 封入藍寶石製之放電容器的準分子放電燈。 (專利文獻1)日本特開2003-59457號公報 (專利文獻2)日本專利第3 1 7 8 1 6 2號公報 【發明內容】 (發明所欲解決之課題） 根據專利文獻1的記載，利用具有由金屬鋁（A1 )、 給（Hf)、釔（Y)、或钪（Sc)的至少1個所形成的無 定形構造的氧化物，被覆石英玻璃製放電容器的內壁，藉 此與未被覆的燈相比較，至少獲得100倍的有效壽命。 但是，在專利文獻1的實施例中係記載一種將作爲稀 有氣體的氙（Xe)與作爲鹵素的氟（F)組合而成的準分 子放電燈，但是被塡充在直徑20mm、長度20cm之放電容 器內的氣體係摻合氙（Xe )與六氟化硫（SF6 )，而爲 31mbar(3100Pa)之低壓，輸入電力亦爲較小的20W。 在如上所述之作動條件下，放電容器並不能形成 20 0°C以上的高溫，覆蓋放電容器之內壁的氧化物被膜係 呈安定狀態，但是爲了在工業上利用採用稀有氣體及鹵素 的準分子放電燈，需要更強的光量，因此，準分子放電燈 -5- 200933691 的直徑爲20mm、長度爲20cm，若非輸入電力40W以上 、氣壓1 3 000Pa以上，即無法獲得充分的光量。 假設在專利文獻1所記載的燈中，若提高封入壓力， 放電容器的溫度即會上升，氟與放電容器內面的被膜會進 行反應，或透過被膜不完全的部分，氟與石英玻璃會進行 反應，因此發光效率會降低，或爲了提高燈電力，而欲提 高輸入電壓時，因電子溫度會上升，在內部電極與發光管 0 內壁之間會產生濺鍍現象，而有可能發生被膜剝離的現象 。若被膜剝離，氟或氯等鹵素會與石英玻璃反應而消耗， 可預測燈的發光強度會急速降低。 另一方面，在專利文獻2係揭示將稀有氣體與鹵素封 入藍寶石製之放電容器之準分子放電燈的一實施例。 本案發明人等係試作專利文獻2之第3圖所示之燈構 成的準分子放電燈，且使用專利文獻1所記載的氬（Ar ) 與氟化物（SF6 )作爲封入氣體。亦即，使用圓筒狀的藍 φ 寶石管作爲放電容器，試作將一對外部電極沿著管壁配設 在管軸方向的ArF準分子放電燈。但是，以作爲工業用所 需之2W/cm2的高管壁負載條件（輸入電力相對於電極面 積的比例）亮燈後，在亮燈後僅1 〇小時，氬一氟的發光 波長193 nm的放射即會消滅。此在專利文獻1中已提及在 由氧化鋁的結晶質所構成的放電容器中，對於氟的屏障作 用並無法檢測出，而形成與此情形相吻合的結果。 本發明之目的在提供一種可在高管壁負載條件下使燈 點亮而保持高光量，並且可長時間作動的稀有氣體鹵素準 -6 - 200933691 分子放電燈。 (解決課題之手段） 本發明爲解決上述課題，採用如下所示之手段。 第1手段係一種準分子放電燈，係在由藍寶石、YAG 、或單結晶氧化釔之至少1個所構成的放電容器的外表面 設置至少1個外部電極，在前述放電容器內封入含有氬（ 0 Α〇與氟（F)原子的氣體的準分子放電燈，其特徵爲： 由前述放電容器的內表面至ΙΟΟμιη爲止的深度區域所包含 的金屬雜質濃度爲600wtppm以下。 第2手段係在第1手段之準分子放電燈中，前述放電 容器係構成爲管狀，在該放電容器內係封入有氬（A〇與 六氟化硫（SF6)與氦（He)或氖（Ne)，在前述放電容 器的外表面，係沿著管軸方向設置至少1個外部電極，前 述放電容器係跨及全周在前述放電容器的兩端側具有未設 φ 有外部電極的外表面部分。 第3手段係在第1手段之準分子放電燈中，前述放電 容器係構成爲大致直方體狀，在該放電容器內係封入有氬 (Ar )與六氟化硫（SF6 )與氦（He )或氖（Ne )，在前 述放電容器的外表面，係沿著長邊方向設置至少1個外部 電極，前述放電容器係跨及全周在前述放電容器的端側具 有未設有外部電極的外表面部分。 第4手段係在第2手段或第3手段之準分子放電燈中 ，前述氖（Ne)佔全封入氣體的莫耳濃度爲90%以上、 200933691 9 9 · 5 %以下。 第5手段係在第2手段或第3手段之準分子放電燈中 ，前述氨（He)佔全封入氣體的莫耳濃度爲90%以上、 9 9.5 %以下。 (發明之效果） 藉由本發明’除了在放電容器使用具有良好熱傳導性 φ 的藍寶石' YAG、氧化釔等耐電漿性高、而且具透光性的 高熔點材料的單結晶材料以外，由於降低放電容器之內表 面區域的金屬雜質濃度，因此鹵素與金屬雜質接觸的機會 變少，因而可抑制在放電容器內壁面的鹵素的反應，而可 防止準分子發光之紫外線的發光強度衰減。 此外，當形成爲：具備有管狀或大致直方體狀的放電 容器，在放電容器的外表面，沿著管軸方向或長邊方向設 置至少1個外部電極，在放電容器內封入氬（Ar)與六氟 φ 化硫（SF6)，放電容器係跨及全周在其容器端部側具有 未設置電極的外表面部分的構造時’若封入有氨（He)或 氖（Ne)，由於具有高於氬（Ar)的熱傳導率，因此由放 電容器內的放電部所發出的熱會迅速傳播至放電部以外的 區域，而將放電容器內的氣體溫度保持爲較低’因此可防 止燈的發光效率降低。 【實施方式】 使用第1圖至第5圖’說明本發明之一實施形態。 -8 - 200933691 第1圖（a)係由通過本實施形態之發明之準分子放 電燈之管軸的切斷面所觀看的剖面圖，第1圖（b)係由 垂直於第1圖（a)所示之準分子放電燈之管軸之切斷面 A-A所觀看的剖面圖。 如該等圖所示，該準分子放電燈1的放電容器2爲直 管狀，藉由對於150至4 OOnm的紫外線具有光透光性，並 且氟離子的吸收較少的藍寶石、YAG、單結晶氧化釔的任 0 —單結晶所構成的材料所構成。此外，在放電容器2內係 封入氬（Ar)及化學安定性較高的六氟化硫（SF6 )作爲 發光氣體’而且封入佔全封入氣體的莫耳濃度爲90%以上 、99.5 %以下的氦（He)或氖（Ne)作爲緩衝氣體。在準 分子放電燈1亮燈時，發光氣體形成氫離子及氟離子。其 中’以放電容器而言’與YAG或氧化釔相比，藍寶石的 透光性佳’亦確 ii* 使用 EFG 法（Edge-defined Film-fed Growth Method)的板材、管材的生產方法，因此在工業 Q 上較容易生產，故較爲理想。 通常放電容器2由於作爲材料的藍寶石、Yag、單結 晶氧化釔的單結晶的任一者經由使用金屬坩堝的製造步驟 予以製造’因此含有作爲金屬雜質的鉬（Mo)、鐵（Fe) 、鉻（Cr)等遷移金屬。以放電容器2的材料而言，若針 對使用藍寶石的情形予以例示，在放電容器2的內表面存 在有因在單結晶成長時之原子排列時所發生的排他現象所 離析的鉬（Mo)、鐵（Fe)、鉻（Cr)等金屬雜質。當存 在該等金屬雜質時’在.放電時SF6分爲F2與S，F2與金屬 -9- 200933691 雜質發生反應而產生金屬鹵化物，由準分子放電燈所放射 的193 nm的光束會減少，而造成短壽命的原因。經化學分 析結果，判明該金屬雜質係由放電容器2的內表面至大致 100數十μιη的深度爲止進行離析。其中，所謂距離放電 容器2之內表面ΙΟΟμπι的深度，係有藍寶石結晶成長時因 離析而使金屬雜質主要存在的深度，而且亮燈時因閥溫度 上升等，得以在閥內表面擴散的距離的意涵。 0 因此，在本發明中，將放電容器2的內表面以磷酸或 硫酸進行化學鈾刻處理，形成爲由放電容器2的內表面至 ΙΟΟμιη的範圍內之鉬（Mo)、鐵（Fe)、鉻（Cr)等金屬 雜質總和濃度爲600ppm以下的狀態。其中，除了化學蝕 刻以外，亦可藉由機械硏磨，將表面的金屬雜質濃度形成 爲5 Oppm以下的狀態。此外，在燈的製造步驟中，一般而 言爲了針對放電容器將吸附在容器內壁的水分去除，例如 在真空爐或乾燥空氣爐內進行乾燥處理，但是在本發明的 0 燈中，亦最好例如在50(TC以上之十分高的溫度下進行熱 處理，藉此盡量減少放電容器2內壁的水分量。 如第1圖（a)所示，放電容器2的管軸方向的兩端 係呈開放，在其兩端設有杯狀之作爲金屬製蓋件的蓋構件 3、4。蓋構件3、4的材料例如爲鎳（Ni )。蓋構件3、4 若考慮到放熱性，以金屬材料最爲適合，但是若放熱性不 成問題，則亦可爲氧化鋁等陶瓷。在放電容器2與蓋構件 3、4之間係塡充密封材5、6,藉此接合放電容器2與蓋 構件3、4而予以密閉。以密封材5、6的材料而言，係使 -10 - 200933691 用例如由銀與銅的合金（Ag-Cu合金）所構成的焊材。在 第2蓋構件4設有氣體配管7，藉由氣體配管7將放電容 器2的內部空間8進行排氣而減壓後，封入作爲發光氣體 的氬（Ar )與化學安定性高的六氟化硫（SF6 )、及作爲 緩衝氣體的氦（He)或氖（Ne)。在封入該等氣體之後， 氣體配管7係利用壓接等形成密封部9，藉此形成爲密閉 構造。 0 在放電容器2的外面，係以使一對外部電極1〇'11 彼此電性分離的方式予以配置，並且以沿著放電容器2之 管軸方向延伸的方式設置。此外，外部電極10、11係與 密封材5、6及蓋構件3、4分離而設。外部電極10、11 係將例如將銅（Cu )形成爲膏狀者塗佈在放電容器2的外 面而形成，或藉由接著劑等，將板狀之例如鋁接著在放電 容器2的外表面而形成。在外部電極10、11之長邊方向 的一端，藉由例如焊材14、15等將引腳12、13作電性連 φ 接。外部電極1 0、1 1間之沿面最短距離係構成爲比隔著 外部電極10、11間之放電空間的最短距離爲長。其係基 於形成爲僅在放電空間發生放電的構造之故。 準分子放電燈1亮燈時，若在一對外部電極10、11 之間施加電壓，會隔著放電容器2，在外部電極10、11間 發生放電。若發光氣體爲氬（Ar)與六氟化硫（SF6)， 該等氣體被電離，形成氬離子與氟離子，形成由氬-氟所 構成的準分子分子，由放電容器2放射193 nm波長的光。 在放電容器2的管軸方向中’外部電極1〇、11設在 -11 - 200933691 距離密封材5、6與蓋構件3、4較遠的位置，藉此在放電 容器2的內部空間8，在由位於管軸方向之L1之範圍內 的外部電極10、11的端部至密封材5、6爲止的範圍L2 內並不會發生放電。亦即，放電容器2係跨及全周在放電 容器2的兩端側具有未設有外部電極10、11的外表面部 分，因此與L1的範圍相對應的內部空間相比較，與L2的 範圍相對應的內部空間形成爲溫度較低的冷卻區域。因此 ，當在放電容器2的內部空間8封入如六氟化硫（SF6 ) 之類之化學安定性較高的氣體作爲發光氣體時，在未發生 放電的放電容器2的管軸方向的L2的區域中，會發生因 放電而電離的氟離子會回到電離前之六氟化硫的反應。藉 此，在放電容器2的內部空間8中，在自位於管軸方向之 L1的範圍內的外部電極10、11的端部至密封材5、6爲 止之間，係抑制與氟離子相接，可抑制構成密封材5、6 或蓋構件3、4的材料與氟離子的反應。 以下說明用以避免沿面放電之供絕緣之用的距離與供 冷卻之用的距離的關係。在屬於蓋構件3、4的金屬製蓋 件（cap)中，爲了不會發生鹵素與金屬蓋（metal cap) 的反應，必須使放電不會接觸到金屬蓋。其條件係使外部 電極10、11與屬於金屬蓋的蓋構件3、4的距離比外部電 極 10、Π間之放電氣體中的距離（放電隙（discharge gap ))爲長。當在放電容器2內封入六氟化硫（SF6 )時 ，由於六氟化硫（SF6 )所具有的絕緣性，用以安定保持 放電的電壓會變高。當以較高的電壓進行驅動時，會有並 -12- 200933691 非爲放電氣體的放電，而是在外部電極10、11間 面放電的危險性。因此，用以不會發生沿面放電而 氣體中安定地保持放電的條件雖較不是取決於六氟 sf6)濃度、放電氣壓，但是在獲得實用上之準分 光效率的全壓lOOTorr ( l 33 30Pa)以上中，係藉由 最短距離比放電隙（隔著外部電極間10、11之放 的最短距離）更長來達成。 ^^另一方面，爲了冷卻放電容器2，作爲放熱部。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 Discharge lamps, in particular, relate to an excimer discharge lamp that utilizes a dielectric barrier discharge to obtain excimer luminescence of a rare gas and fluorine. ❹ 【Prior Art】 Excimer discharge lamps that have been enclosed with rare gases and halogens have completely different emission characteristics from other lamps such as high-pressure mercury lamps or metal halide lamps, especially 'lights that can be efficiently generated in high-pressure mercury lamps or metal halide lamps. Ultraviolet wavelengths that are not available in the medium. The excimer discharge lamp can select the wavelength of the emitted ultraviolet light by combining the enclosed rare gas and halogen. For example, in the combination of argon (Ar) and fluorine (φ F), ultraviolet rays in the vicinity of 193 nm can be obtained, and in the combination of krypton (Kr) and fluorine (F), ultraviolet rays near 248 nm can be obtained in X (Xe). In combination with fluorine (F), ultraviolet rays in the vicinity of 351 nm can be obtained. In particular, in an ArF excimer discharge lamp for obtaining ultraviolet rays having a wavelength of 193 nrn used in a photolithography method of a semiconductor, or a KrF excimer discharge lamp for obtaining ultraviolet rays having a wavelength of 24 nm, the characteristics of the photoresist can be utilized. Test, mask inspection, etc. Patent Document 1 discloses an excimer discharge lamp in which an inner surface of a discharge vessel composed of quartz glass is coated with an inactive layer of a metal oxide, and a rare gas and a dentate are sealed in a discharge capacitor-4 - 200933691 . It has been described that when fluorine or chlorine as a halogen is sealed in a quartz glass discharge vessel, halogen atoms and ions immediately react with quartz glass to generate antimony halide and oxygen, and thus do not undergo excimer discharge, and therefore must be coated with quartz. Inside the glass. Further, Patent Document 2 discloses an excimer discharge lamp in which a rare gas and a halogen are sealed in a discharge vessel made of sapphire. (Patent Document 1) Japanese Laid-Open Patent Publication No. 2003-59457 (Patent Document 2) Japanese Patent No. 3 1 7 8 1 6 2 (Problems to be Solved by the Invention) According to the description of Patent Document 1, An oxide having an amorphous structure formed of at least one of metal aluminum (A1), (Hf), yttrium (Y), or yttrium (Sc), coated with an inner wall of a quartz glass discharge vessel, whereby Compared with the covered lamp, at least 100 times the effective life is obtained. However, in the example of Patent Document 1, an excimer discharge lamp in which cerium (Xe) which is a rare gas and fluorine (F) which is a halogen are combined is described, but is filled with a diameter of 20 mm and a length of 20 cm. The gas system in the discharge vessel is blended with xenon (Xe) and sulfur hexafluoride (SF6) to a low pressure of 31 mbar (3100 Pa), and the input power is also a small 20 W. Under the above-mentioned operating conditions, the discharge vessel cannot form a high temperature of 20 ° C or higher, and the oxide film covering the inner wall of the discharge vessel is in a stable state, but in order to industrially utilize a rare gas and a halogen. The molecular discharge lamp requires a stronger amount of light. Therefore, the excimer discharge lamp-5-200933691 has a diameter of 20 mm and a length of 20 cm. If the input power is 40 W or more and the air pressure is 13,000 Pa or more, a sufficient amount of light cannot be obtained. In the lamp described in Patent Document 1, when the sealing pressure is increased, the temperature of the discharge vessel rises, and the fluorine reacts with the film on the inner surface of the discharge vessel, or the portion where the film is not completely penetrated, and fluorine and quartz glass are allowed to proceed. In response to the reaction, the luminous efficiency is lowered, or in order to increase the lamp power, when the input voltage is to be increased, the electron temperature rises, and sputtering occurs between the internal electrode and the inner wall of the arc tube 0, and the film may be peeled off. The phenomenon. When the film is peeled off, halogen such as fluorine or chlorine is consumed by reacting with the quartz glass, and it is predicted that the luminous intensity of the lamp is rapidly lowered. On the other hand, Patent Document 2 discloses an embodiment of an excimer discharge lamp in which a rare gas and a halogen are sealed in a discharge vessel made of sapphire. In the case of the inventors of the present invention, an excimer discharge lamp comprising a lamp shown in Fig. 3 of Patent Document 2 is used, and argon (Ar) and fluoride (SF6) described in Patent Document 1 are used as an enclosed gas. In other words, a cylindrical blue φ gemstone tube was used as a discharge vessel, and an ArF excimer discharge lamp in which a pair of external electrodes were arranged along the tube wall in the tube axis direction was attempted. However, after the high wall load condition (the ratio of the input power to the electrode area) of 2 W/cm 2 required for industrial use is illuminated, only 1 〇 hours after the lighting, the argon-fluorine emission wavelength is 193 nm. The radiation will be eliminated. As described in Patent Document 1, in the discharge vessel composed of the crystallinity of alumina, the barrier effect on fluorine is not detected, and the result coincides with this case. SUMMARY OF THE INVENTION An object of the present invention is to provide a rare gas halogen quasi--6-200933691 molecular discharge lamp which can illuminate a lamp under high wall load conditions while maintaining a high amount of light and can be operated for a long period of time. (Means for Solving the Problem) In order to solve the above problems, the present invention employs the following means. The first means is an excimer discharge lamp in which at least one external electrode is provided on an outer surface of a discharge vessel composed of at least one of sapphire, YAG or single crystal yttria, and argon (0) is enclosed in the discharge vessel. An excimer discharge lamp of a gas of fluorene and fluorine (F) atoms, characterized in that the concentration of the metal impurities contained in the depth region from the inner surface of the discharge vessel to ΙΟΟμη is 600 wtppm or less. The second means is the first In the excimer discharge lamp of the method, the discharge vessel is formed in a tubular shape, and argon (A 〇 and sulfur hexafluoride (SF6), 氦 (He) or 氖 (Ne)) are sealed in the discharge vessel, and the discharge is performed. The outer surface of the container is provided with at least one external electrode along the tube axis direction, and the outer surface of the discharge vessel has an outer surface portion on the both end sides of the discharge vessel without φ having an external electrode. In the excimer discharge lamp of the first aspect, the discharge vessel is configured in a substantially rectangular parallelepiped shape, and argon (Ar) and sulfur hexafluoride (SF6) and helium (He) or helium are sealed in the discharge vessel. Ne ) At least one external electrode is disposed on the outer surface of the discharge vessel along the longitudinal direction, and the discharge vessel has an outer surface portion on the end side of the discharge vessel that is not provided with an external electrode over the entire circumference. In the excimer discharge lamp of the second means or the third means, the cerium (Ne) accounts for 90% or more of the total enclosed gas, and 200933691 99.5% or less. The fifth means is the second means. In the excimer discharge lamp of the third aspect, the ammonia (He) accounts for 90% or more and 99.5 % or less of the total entrapped gas. (Effect of the invention) By the present invention, in addition to being used well in a discharge vessel In addition to the single crystal material of the high-melting material such as sapphire 'YAG and ytterbium oxide having high thermal conductivity φ, which is high in plasma resistance and light transmissive, the halogen is in contact with metal impurities due to the decrease in the concentration of metal impurities in the inner surface region of the discharge vessel. Since the chance of the halogen is reduced, the reaction of the halogen on the inner wall surface of the discharge vessel can be suppressed, and the emission intensity of the ultraviolet light emitted by the excimer can be prevented from being attenuated. a discharge vessel having a shape of a substantially rectangular parallelepiped, at the outer surface of the discharge vessel, at least one external electrode is disposed along the tube axis direction or the longitudinal direction, and argon (Ar) and hexafluoro φ sulphur (SF6) are sealed in the discharge vessel. When the discharge vessel is spanned and has a configuration in which the outer surface portion of the electrode is not provided on the end side of the container, 'if ammonia (He) or neon (Ne) is enclosed, heat conduction is higher than argon (Ar). Since the heat generated by the discharge portion in the discharge vessel rapidly propagates to a region other than the discharge portion, the temperature of the gas in the discharge vessel is kept low. Therefore, the luminous efficiency of the lamp can be prevented from being lowered. An embodiment of the present invention will be described using Figs. 1 to 5'. -8 - 200933691 Fig. 1(a) is a cross-sectional view taken along the cut surface of the tube axis of the excimer discharge lamp of the present invention, and Fig. 1(b) is perpendicular to Fig. 1 ( a) A cross-sectional view of the cut surface AA of the tube axis of the excimer discharge lamp shown. As shown in the figures, the discharge vessel 2 of the excimer discharge lamp 1 has a straight tubular shape, and is sapphire, YAG, and single crystal having light transmittance for ultraviolet rays of 150 to 400 nm and less absorption of fluorine ions. Any of the materials consisting of yttrium oxide and single crystal. Further, argon (Ar) and hexafluoride hexafluoride (SF6) having high chemical stability are sealed as luminescent gas in the discharge vessel 2, and the molar concentration of the fully enclosed gas is 90% or more and 99.5% or less. Helium (He) or helium (Ne) is used as a buffer gas. When the quasi-molecular discharge lamp 1 is turned on, the luminescent gas forms hydrogen ions and fluoride ions. Among them, 'in the case of a discharge vessel', compared with YAG or yttrium oxide, the sapphire has good light transmittance, and it is also ii* using the EFG method (Edge-defined Film-fed Growth Method) for the production of plates and tubes. Industrial Q is easier to produce, so it is ideal. In general, the discharge vessel 2 is manufactured by using any of the single crystals of sapphire, Yag, and single crystal yttrium oxide as a material, and thus contains molybdenum (Mo), iron (Fe), and chromium as metal impurities. (Cr) and other migration metals. In the case of the material of the discharge vessel 2, if it is exemplified for the case of using sapphire, there is a molybdenum (Mo) which is isolated from the exclusive phenomenon which occurs when the atoms are arranged in the single crystal growth on the inner surface of the discharge vessel 2, Metal impurities such as iron (Fe) and chromium (Cr). When these metal impurities are present, SF6 is divided into F2 and S at the time of discharge, and F2 reacts with the metal-9-200933691 impurity to produce a metal halide, and the 193 nm beam emitted by the excimer discharge lamp is reduced. And cause short life. As a result of the chemical analysis, it was found that the metal impurities were separated from the inner surface of the discharge vessel 2 to a depth of approximately 100 tens of μm. The depth of the inner surface of the discharge vessel 2 is ΙΟΟμπι, which is the depth at which metal impurities are mainly present due to segregation when the sapphire crystal grows, and the distance spread on the inner surface of the valve due to the rise in valve temperature during lighting. Meaning. Therefore, in the present invention, the inner surface of the discharge vessel 2 is subjected to chemical uranium engraving treatment with phosphoric acid or sulfuric acid, and is formed into molybdenum (Mo), iron (Fe), and the like from the inner surface of the discharge vessel 2 to the range of ΙΟΟμηη. The total concentration of metal impurities such as chromium (Cr) is 600 ppm or less. Among them, in addition to chemical etching, the metal impurity concentration on the surface may be set to a state of 5 Oppm or less by mechanical honing. Further, in the manufacturing step of the lamp, in general, in order to remove moisture adsorbed on the inner wall of the container for the discharge vessel, for example, drying in a vacuum furnace or a dry air furnace, in the 0 lamp of the present invention, For example, heat treatment is performed at a very high temperature of 50 (TC or higher), thereby minimizing the moisture content of the inner wall of the discharge vessel 2. As shown in Fig. 1(a), both ends of the discharge vessel 2 in the tube axis direction are The cover member 3, 4 is formed in a cup shape as a metal cover member at both ends thereof. The material of the cover members 3, 4 is, for example, nickel (Ni). The cover members 3, 4 are considered to be exothermic, The metal material is most suitable, but if the heat release property is not a problem, it may be a ceramic such as alumina. The sealing members 5 and 6 are interposed between the discharge vessel 2 and the cover members 3 and 4, thereby joining the discharge vessel 2 and The cover members 3 and 4 are sealed. In the case of the materials of the seal members 5 and 6, a weld material composed of, for example, an alloy of silver and copper (Ag-Cu alloy) is used for the -10, 2009, and the second cover. The member 4 is provided with a gas pipe 7, and the inside of the discharge vessel 2 is empty by the gas pipe 7. After the gas is decompressed and decompressed, the argon (Ar) as a luminescent gas, sulfur hexafluoride (SF6) having high chemical stability, and helium (He) or neon (Ne) as a buffer gas are sealed. After the gas, the gas pipe 7 is formed into a sealing portion 9 by pressure bonding or the like, thereby forming a hermetic structure. 0 On the outer surface of the discharge vessel 2, a pair of external electrodes 1''11 are electrically separated from each other. It is disposed and provided to extend in the tube axis direction of the discharge vessel 2. Further, the external electrodes 10 and 11 are provided separately from the sealing members 5 and 6 and the cover members 3 and 4. The external electrodes 10 and 11 are For example, a copper (Cu) paste is formed on the outer surface of the discharge vessel 2, or a plate-like aluminum such as aluminum is formed on the outer surface of the discharge vessel 2 by an adhesive or the like. At one end of the longitudinal direction of the ellipse, the pins 12 and 13 are electrically connected by φ, for example, by soldering materials 14, 15, etc. The shortest distance between the external electrodes 10 and 1 is configured to be externally separated. The shortest distance of the discharge space between the electrodes 10, 11 is long. When the excimer discharge lamp 1 is turned on, when a voltage is applied between the pair of external electrodes 10 and 11, the discharge vessel 2 is interposed and discharge occurs between the external electrodes 10 and 11. If the luminescent gas is argon (Ar) and hexafluoride hexafluoride (SF6), the gases are ionized to form argon ions and fluoride ions to form an excimer molecule composed of argon-fluorine, and the discharge vessel 2 emits a wavelength of 193 nm. In the tube axis direction of the discharge vessel 2, the external electrodes 1〇, 11 are located at a position far from the sealing members 5, 6 and the cover members 3, 4 from -11 to 200933691, thereby being inside the discharge vessel 2 In the space 8, the discharge does not occur in the range L2 from the end of the external electrodes 10, 11 in the range of L1 in the tube axis direction to the seal members 5, 6. That is, the discharge vessel 2 has the outer surface portions on the both end sides of the discharge vessel 2 that are not provided with the external electrodes 10, 11 over the entire circumference, and therefore the internal space corresponding to the range of L1 is compared with the range of L2. The corresponding internal space is formed as a cooling zone of lower temperature. Therefore, when a gas having a high chemical stability such as sulfur hexafluoride (SF6) is enclosed as a luminescent gas in the internal space 8 of the discharge vessel 2, L2 in the tube axis direction of the discharge vessel 2 in which no discharge occurs In the region, fluoride ions ionized by the discharge will return to the reaction of hexafluoride before ionization. Thereby, in the internal space 8 of the discharge vessel 2, the end of the external electrodes 10, 11 in the range from the L1 in the tube axis direction to the sealing members 5, 6 is prevented from coming into contact with the fluoride ions. The reaction between the materials constituting the sealing members 5, 6 or the cover members 3, 4 and the fluorine ions can be suppressed. The relationship between the distance for insulation for creeping discharge and the distance for cooling is described below. In the metal cap belonging to the cover members 3, 4, in order not to cause a reaction between the halogen and the metal cap, it is necessary to prevent the discharge from coming into contact with the metal cap. The condition is such that the distance between the external electrodes 10, 11 and the cover members 3, 4 belonging to the metal cover is longer than the distance (discharge gap) in the discharge gas between the external electrodes 10 and the turns. When sulfur hexafluoride (SF6) is sealed in the discharge vessel 2, the voltage for maintaining the discharge is stabilized due to the insulating property of sulfur hexafluoride (SF6). When driving at a higher voltage, there is a danger that the discharge of the discharge gas is not -12-200933691, but is discharged between the external electrodes 10, 11. Therefore, the condition for maintaining the discharge stably in the gas without causing creeping discharge is less dependent on the concentration of hexafluorosf6) and the discharge gas pressure, but a full pressure of 100 Torr (l 33 30 Pa) at which practical quasi-spectroscopic efficiency is obtained. In the above, it is achieved by the shortest distance being longer than the discharge gap (the shortest distance between the external electrodes 10 and 11). ^^ On the other hand, in order to cool the discharge vessel 2, as a heat release unit
P 金屬蓋件的蓋構件3、4與外部電極10、11的距離 爲有利。 因此，不會發生因鹵素與金屬蓋件的反應以致 降低，而且不會發生沿面放電而穩定維持放電所需 形成爲：放電隙$沿面最短距離、而且放電隙 < 外 與金屬蓋件間的距離。 第2圖係顯示作爲緩衝氣體之氖（Ne)佔全封 φ 的莫耳濃度與發光效率的關係的曲線圖。 該曲線圖係顯示使用M (Ar)作爲有助於發光 氣體，使用SF6作爲含氟氣體，使用Ne作爲緩衝 以全壓1〇〇、200、4001'〇1^，使佔氬（八1：)與氖（： 總和的氖（Ne)的莫耳濃度改變時的準分子發光（ )效率（相對値）。 如該圖所示，照度十分安定的是氖（Ne)比率: 以上的區域，但是在氖（N e )比率極高（9 9.5 %以 區域中，發光效率降低情形變得顯著。 產生沿 在放電 化硫（ 子光發 使沿面 電空間 之屬於 愈近愈 鹵素量 要件係 部電極 入氣體 的稀有 氣體， Me)之 1 9 3 nm U 9 0 % 上）的 -13- 200933691 第3圖係顯示作爲緩衝氣體的氨（He)佔全封入氣體 的莫耳濃度與發光效率的關係的曲線圖。 該曲線圖係顯示使用氬（Ar)作爲有助於發光的稀有 氣體’使用SF6作爲含氟氣體’使用Ne作爲緩衝氣體， 以全壓100、200、400Torr’使佔氬（Ar)與氦（He)之 總和的氦（He )的莫耳濃度改變時的準分子發光（丨9 3 nm )效率（相對値）。 如該圖所示’照度十分安定的是氦（He)比率爲90% 以上的區域，但是在氦（He )比率極高（99.5%以上）的 區域中，發光效率降低情形變得顯著。 以下顯示用以進行後述之比較實驗的本發明之準分子 放電燈的實施例。 (1)放電容器的規格：材料：單結晶藍寶石；形狀 :圓筒形；壁厚：1mm;長度：2〇〇mm;直徑：10mm;距 離放電容器內表面100μιη之深度中的平均金屬雜質濃度： 2 00wtppm 以下 (2 )電極的規格：材料：銀（印刷膏材）；形狀： 針對圓筒形之放電容器的軸呈對稱相對向；長度：l4〇inm :寬度：2mm ;隔著放電空間的電極間分離距離：丨〇mm (3)蓋構件的規格：材料：鎳；蓋構件與外部電極 間的距離：3 0 m m (4 )密封材的規格：材料：Ag_Cu合金（銀焊材） (5)封入氣體的規格：Ar:丨58xl〇3pa、Sp6 : Ne : 7·84Χΐ〇\、全壓 8.〇χ1〇4ρ& 200933691 (6 )亮燈條件：3kV ( 0-peak ) 、70kHz的脈衝電壓 施加 (7) 自放電容器內表面至ΙΟΟμιη爲止的金屬雜質濃 度爲600wtppm以下。以供其之用的實現手段而言，若爲 藍寶石管，即以氟酸進行化學蝕刻，或藉由離子束進行乾 式蝕刻或機械切削。 (8) 雜質濃度的測定係在藍寶石管之中放入磷酸 $ 62%、硫酸38%的混合液，將藍寶石管的兩端以鐵氟龍（ 註冊商標）片帶（tape )密封，在置於微波爐的狀態下放 置5小時左右。之後，回收液體，利用ICP (感應耦合型 電漿發光分析），以校正曲線法（calibration curve method)進行定量分析。 其中，在以上說明中係就藍寶石管加以敘述，但是， 即使爲YAG或單結晶氧化釔，亦在結晶成長時之金屬雜 質進行離析方面，會有與藍寶石共通的問題，即使在使用 φ YAG或單結晶氧化釔作爲放電容器的情形下，亦必須去除 內表面的金屬雜質。 (比較實驗1 ) 分自各製作3支：將具有第1圖所示形狀的放電容器 的內面進行化學蝕刻，將由放電容器內表面至ΙΟΟμηι爲止 的深度區域所包含的金屬雜質濃度設爲600wtppm以下之 由藍寶石管所構成的ArF準分子放電燈；及在結晶成長後 ，未將具有第1圖所示形狀的放電容器的內表面進行化學 -15- 200933691 蝕刻之由藍寶石管所構成的ArF準分子放電燈，改變閥負 載，調查193 nm之發光強度之時間上的變化。 第4圖係顯示比較實驗1之結果的表。如該圖所示， 可知與未施行化學蝕刻的準分子燈4、5、6相比較，在放 電容器的內表面施行化學鈾刻的準分子燈1、2、3的光輸 出壽命大幅獲得改善。 0 (比較實驗2) 備妥將具有第1圖所示形狀的放電容器的內表面置入 磷酸62%、硫酸38%的混合液且放入微波爐，各自經5小 時、4小時、3小時、2小時洗淨處理後的ArF準分子放 電燈7、8、9、10、及未對具有第1圖所示形狀的放電容 器的內表面進行洗淨處理的ArF準分子放電燈11、12。 針對所備妥的ArF準分子放電燈7至12，調查由ArF準 分子放電燈所放射的193 nm的光束維持特性。在此所謂光 φ 束維持率係指將亮燈初期設爲100%的情形下經過400小 時時（對於燈所要求的亮燈時間）中的光束維持的比例。 第5圖係顯示比較實驗2之結果的表。如該圖所示， 如ArF準分子放電燈7所示，經過400小時時，雖然亦會 有光束上升者，但是在經過400小時的時間點，70%以下 可謂爲已達壽命（更換時期），因此將由放電容器內表面 至 100 μιη爲止的深度區域所包含的金屬雜質濃度 600wtppm稱爲金屬雜質濃度的上限。之所以表面金屬雜 質濃度愈高，光束衰減愈大，係基於氟減少所致。 -16- 200933691 接著，使用第6圖說明本發明之第2實施形態。 第6圖（a)係由平行於本實施形態之發明之準分子 放電燈之長邊方向的切斷面所觀看的剖面圖’第6圖（b )係由切斷面A-A觀看第6圖（a)之準分子放電燈的剖 面圖。 如該等圖所示，該準分子放電燈21的放電容器22係 大致直方體狀，對於150至400nm的紫外線具有光透光性 0 ，並且藉由由氟離子吸收較少的藍寶石、YAG、單結晶氧 化釔之任一單結晶所構成的材料所構成。此外，在放電容 器22內係封入氬（Ar)與化學安定性高的六氟化硫（Sf6 )作爲發光氣體’而且封入佔全封入氣體的莫耳濃度爲 90¾以上、99.5 %以下的氦（He)或氖（Ne)作爲緩衝氣 體。準分子放電燈1亮燈時，發光氣體會形成氬離子及氟 離子。 將放電容器22的內表面以磷酸或硫酸進行化學蝕刻 〇 處理，形成爲由放電容器22的內表面至100 μιη的範圍內 之鉬（Mo )、鐵（Fe )、鉻（cr )等金屬雜質總和濃度爲 6〇〇Ppm以下的狀態。其中，除了化學蝕刻以外，亦可藉 由機械硏磨，將表面的金屬雜質濃度形成爲5〇ppm以下的 狀態。 如第6圖（a)所示，放電容器Μ之長邊方向中的— 端係㈣放’在該㈣置杯狀之作爲金屬製蓋件的蓋構件 23。蓋構件23的材料例如爲科伐合金“ο”。。蓋構件 2 3若考慮到放熱性 以金屬材料最爲適合，但是若放熱性 -17- 200933691 不成問題，則亦可爲氧化鋁等陶瓷。在放電容器22與蓋 構件23之間係塡充例如由Ag-Cu合金所構成的密封材24 ，藉此接合放電容器22與蓋構件23而予以密閉。以密封 材24的材料而言，係使用例如由銀與銅的合金（Ag-Cu 合金）所構成的焊材。在蓋構件23設有氣體配管25，藉 由氣體配管25將放電容器22的內部空間26進行排氣而 減壓後，封入作爲發光氣體的氬（Ar )與化學安定性高的 φ 六氟化硫（SF6 )、及作爲緩衝氣體的氦（He )或氖（Ne )。在封入該等氣體之後，氣體配管25係利用壓接等形 成密封部2 7，藉此形成爲密閉構造。 在放電容器22的外面係以一對例如由金（Au)所構 成的板狀外部電極28與網狀外部電極29相互電性分離的 方式作配置，並且以沿著放電容器22的長邊方向延伸的 方式而設。此外，外部電極28、29係遠離密封材24及蓋 構件23而設。在外部電極28、29的長邊方向的一端係藉 φ 由例如焊材32、33等，將引腳30、31作電性連接。外部 電極28、29間的沿面最短距離係構成爲比隔著外部電極 28、29間之放電空間的最短距離爲長。此係基於形成爲僅 在放電空間發生放電的構造之故。 準分子放電燈21亮燈時，若在一對外部電極28、29 之間施加電壓，會隔著放電容器22而在外部電極28、29 間發生放電。若發光氣體爲氬（Ar )與六氟化硫（SF6 ) ，該等氣體被電離，形成氬離子與氟離子，形成由氬一氟 所構成的準分子分子，193 nm的波長的光會由放電容器2 -18- 200933691 放射。 在放電容器22的長邊方向中，將外部電極28、29設 在遠離密封材24與蓋構件23的位置，藉此在放電容器22 的內部空間26中，由位於長邊方向之L3之範圍內的外部 電極28、29的端部至密封材424爲止的範圍L4並未發生 放電。亦即，放電容器22係跨及全周在放電容器22的一 端側具有未設有外部電極28、29的表面部分，因此，相 0 較於與L3的範圍相對應的內部空間，與L4的範圍相對應 的內部空間係形成爲溫度較低的冷卻區域。因此，當在放 電容器22的內部空間26封入如六氟化硫（SF6 )之類之 化學安定性較高的氣體作爲發光氣體時，在未發生放電的 放電容器22的長邊方向的L4的區域中，係會發生因放電 而電離的氟離子回到電離前的六氟化硫的反應。藉此’在 放電容器22的內部空間26中，在由位於長邊方向之L3 的範圍的外部電極28、29的端部至密封材24爲止之間係 φ 抑制與氟離子相接，而可抑制構成密封材24或蓋構件23 的材料與氟離子的反應。不會發生因鹵素與金屬蓋件的反 應以致鹵素量降低，而且不會發生沿面放電而穩定維持放 電所需要件係形成爲放電隙（隔著外部電極28、29間之 放電空間的最短距離）S沿面最短距離、而且放電隙（隔 著外部電極28、29間之放電空間的最短距離）〈外部電 極與金屬蓋件間的距離。 此外，在本實施形態之準分子放電燈21中’亦如第2 圖所示，照度十分安定的是氖（Ne)比率爲90 %以上的區 -19- 200933691 域，但是在氖（Ne)比率極高（99.5 %以上）的區域中， 發光效率降低情形變得顯著，此外，如第3圖所示，照度 十分安定的是氦（He)比率爲9 0%以上的區域，但是在氦 (He )比率極高（99.5%以上）的區域中，發光效率降低 情形變得顯著。 此外，在本實施形態之準分子放電燈21中，亦獲得 與在比較實驗1及比較實驗2中所得相同的實驗結果。 ❹ 【圖式簡單說明】 第1圖係由通過第1實施形態之發明之準分子放電燈 之管軸的切斷面所觀看的剖面圖及由垂直於管軸之切斷面 A-A所觀看的剖面圖。 第2圖係顯示氖（Ne)佔全封入氣體的莫耳濃度與發 光效率的關係的曲線圖。 第3圖係顯示氦（He)佔全封入氣體的莫耳濃度與發 φ 光效率的關係的曲線圖。 第4圖係顯示比較實驗1之結果的表。 第5圖係顯示比較實驗2之結果的表。 第6圖係由平行於第2實施形態之發明之準分子放電 燈之長邊方向的切斷面所觀看的剖面圖及由切斷面A-A所 觀看的剖面圖。 【主要元件符號說明】 1 :準分子放電燈 -20- 200933691 放電容器 4 :蓋構件 6 :密封材 氣體配管 內部空間 密封部 、1 1 :外部電極 、13 :引腳 、：15 :焊材 :準分子放電燈 :放電容器 :蓋構件 :密封材 :氣體配管 :內部空間 :密封部 :板狀外部電極 :網狀外部電極 、31 :引腳 、3 3 :焊材The distance between the cover members 3, 4 of the P metal cover and the external electrodes 10, 11 is advantageous. Therefore, the reaction between the halogen and the metal cover member does not occur, so that the surface discharge does not occur and the sustain discharge is stably formed as follows: the discharge gap is the shortest distance along the surface, and the discharge gap is between the outer metal cover and the metal cover member. distance. Fig. 2 is a graph showing the relationship between the molar concentration of Ne(Ne) as a buffer gas and the molar concentration of the full seal φ and luminous efficiency. The graph shows that M (Ar) is used as a luminescent gas, SF6 is used as a fluorine-containing gas, and Ne is used as a buffer at a total pressure of 1 〇〇, 200, 4001' 〇 1 ^ to make argon (eight 1: And 氖 (: the excimer luminescence (the relative 値) when the molar concentration of 氖 (Ne) is changed. As shown in the figure, the illuminance is very stable is the ratio of 氖 (Ne): the above region, However, in the case where the ratio of 氖(N e ) is extremely high (9 9.5 % in the region, the decrease in luminous efficiency becomes remarkable. The generation of sulphur in the discharge is generated (the sub-light causes the electrical space along the surface to be closer to the halogen component). The rare gas of the gas entering the gas, Me) 1 9 3 nm U 9 0 % above)-13- 200933691 Fig. 3 shows the ammonia concentration (He) as a buffer gas in the molar concentration and luminous efficiency of the fully enclosed gas. A graph showing the relationship between the use of argon (Ar) as a rare gas that contributes to luminescence, 'using SF6 as a fluorine-containing gas', using Ne as a buffer gas, and argon at a total pressure of 100, 200, 400 Torr' ( Change in molar concentration of 氦(He) of Ar) and 氦(He) The excimer luminescence (丨9 3 nm) efficiency (relative 値). As shown in the figure, the illuminance is very stable, the 氦 (He) ratio is more than 90%, but the 氦 (He) ratio is extremely high (99.5). In the region of % or more, the luminous efficiency is lowered. An example of the excimer discharge lamp of the present invention for performing a comparative experiment to be described later is shown below. (1) Specification of the discharge vessel: Material: single crystal sapphire; Shape: cylindrical; wall thickness: 1 mm; length: 2 mm; diameter: 10 mm; average metal impurity concentration in the depth of 100 μm from the inner surface of the discharge vessel: 2 00 wtppm or less (2) Specifications of the electrode: material: silver (printing paste); shape: the axis of the cylindrical discharge vessel is symmetrically opposite; length: l4〇inm: width: 2mm; separation distance between electrodes across the discharge space: 丨〇mm (3) cover member Specifications: Material: Nickel; Distance between cover member and external electrode: 3 0 mm (4) Specification of sealing material: Material: Ag_Cu alloy (silver welding material) (5) Specification of enclosed gas: Ar: 丨58xl〇3pa , Sp6 : Ne : 7·84Χΐ〇\, full pressure 8. Χ1〇4ρ& 200933691 (6) Lighting conditions: 3kV (0-peak), 70kHz pulse voltage application (7) The metal impurity concentration from the inner surface of the discharge vessel to ΙΟΟμηη is 600wtppm or less. In the meantime, if it is a sapphire tube, it is chemically etched with hydrofluoric acid, or dry etching or mechanical cutting by an ion beam. (8) The impurity concentration is determined by placing a mixture of phosphoric acid of 62% and 38% of sulfuric acid in a sapphire tube, and sealing both ends of the sapphire tube with a Teflon (registered trademark) tape. Leave it in the microwave oven for about 5 hours. Thereafter, the liquid was recovered, and quantitative analysis was performed by ICP (Inductively Coupled Plasma Luminescence Analysis) using a calibration curve method. In the above description, the sapphire tube is described. However, even if it is YAG or single crystal yttrium oxide, there is a problem common to sapphire in the separation of metal impurities during crystal growth, even when φ YAG or In the case of single crystal yttrium oxide as a discharge vessel, it is also necessary to remove metal impurities on the inner surface. (Comparative Experiment 1) Three pieces of each were produced: the inner surface of the discharge vessel having the shape shown in Fig. 1 was chemically etched, and the metal impurity concentration included in the depth region from the inner surface of the discharge vessel to ΙΟΟμηι was 600 wtppm or less. An ArF excimer discharge lamp composed of a sapphire tube; and an ArF standard composed of a sapphire tube which is not etched by chemical -15-200933691 after the crystal growth has been performed, and the inner surface of the discharge vessel having the shape shown in Fig. 1 is not grown. The molecular discharge lamp, changing the valve load, investigated the change in the luminescence intensity at 193 nm. Figure 4 is a table showing the results of Comparative Experiment 1. As shown in the figure, it is understood that the light output life of the excimer lamps 1, 2, and 3 which perform chemical uranium engraving on the inner surface of the discharge vessel is greatly improved as compared with the excimer lamps 4, 5, and 6 which are not subjected to chemical etching. . 0 (Comparative Experiment 2) The inner surface of the discharge vessel having the shape shown in Fig. 1 was placed in a mixture of phosphoric acid 62% and sulfuric acid 38%, and placed in a microwave oven for 5 hours, 4 hours, and 3 hours, respectively. ArF excimer discharge lamps 7, 8, 9, and 10 after 2 hours of washing treatment, and ArF excimer discharge lamps 11, 12 which have not been subjected to cleaning treatment of the inner surface of the discharge vessel having the shape shown in Fig. 1 . The 193 nm beam maintenance characteristics of the ArF excimer discharge lamp were investigated for the prepared ArF excimer discharge lamps 7 to 12. Here, the light φ beam maintenance ratio is a ratio of the light beam maintenance in the case where the initial lighting period is set to 100%, and the light beam is maintained for 400 hours (lighting time required for the lamp). Figure 5 is a table showing the results of Comparative Experiment 2. As shown in the figure, as shown in the ArF excimer discharge lamp 7, although the beam rises after 400 hours, at the time of 400 hours, 70% or less can be said to have reached the end of life (replacement period). Therefore, the metal impurity concentration 600 wtppm contained in the depth region from the inner surface of the discharge vessel to 100 μm is referred to as the upper limit of the metal impurity concentration. The higher the surface metal impurity concentration, the greater the beam attenuation, which is based on the reduction of fluorine. -16- 200933691 Next, a second embodiment of the present invention will be described using FIG. Fig. 6(a) is a cross-sectional view taken along the cut surface in the longitudinal direction of the excimer discharge lamp of the invention of the present embodiment. Fig. 6(b) is viewed from the cut surface AA. Fig. 6 (a) A cross-sectional view of an excimer discharge lamp. As shown in the figures, the discharge vessel 22 of the excimer discharge lamp 21 has a substantially rectangular parallelepiped shape, has a light transmissivity of 0 for ultraviolet rays of 150 to 400 nm, and is sapphire, YAG, which is less absorbed by fluorine ions. A material composed of any single crystal of single crystal cerium oxide. Further, argon (Ar) and hexafluoride hexafluoride (Sf6) having high chemical stability are enclosed in the discharge vessel 22 as a luminescent gas', and yttrium having a molar concentration of 902⁄4 or more and 99.5% or less of the total enclosed gas is sealed ( He) or 氖 (Ne) as a buffer gas. When the excimer discharge lamp 1 is turned on, the luminescent gas forms argon ions and fluoride ions. The inner surface of the discharge vessel 22 is chemically etched with phosphoric acid or sulfuric acid to form metal impurities such as molybdenum (Mo), iron (Fe), chromium (cr) and the like from the inner surface of the discharge vessel 22 to 100 μm. The total concentration is below 6 〇〇 Ppm. Among them, in addition to chemical etching, the metal impurity concentration on the surface may be 5 〇 ppm or less by mechanical honing. As shown in Fig. 6(a), the end portion (four) of the longitudinal direction of the discharge vessel is placed in the cup member 23 which is a metal cover member. The material of the cover member 23 is, for example, Kovar "ο". . The cover member 2 3 is most suitable for the metal material in consideration of the heat release property, but if the heat release property -17-200933691 is not a problem, it may be a ceramic such as alumina. A sealing material 24 made of, for example, an Ag-Cu alloy is interposed between the discharge vessel 22 and the lid member 23, thereby sealing the discharge vessel 22 and the lid member 23 to be hermetically sealed. For the material of the sealing material 24, for example, a welding material composed of an alloy of silver and copper (Ag-Cu alloy) is used. The cover member 23 is provided with a gas pipe 25, and the internal space 26 of the discharge vessel 22 is exhausted by the gas pipe 25 to be depressurized, and then argon (Ar) as a luminescent gas and φ hexafluoride having high chemical stability are sealed. Sulfur (SF6), and helium (He) or helium (Ne) as a buffer gas. After the gas is sealed, the gas pipe 25 is formed into a sealed structure by pressure-bonding or the like to form the sealing portion 2, thereby forming a hermetic structure. The outer surface of the discharge vessel 22 is disposed such that a pair of plate-like outer electrodes 28 made of, for example, gold (Au) and the mesh-shaped outer electrode 29 are electrically separated from each other, and along the longitudinal direction of the discharge vessel 22 Extended way. Further, the external electrodes 28 and 29 are provided away from the sealing member 24 and the lid member 23. The leads 30 and 31 are electrically connected to one end of the external electrodes 28 and 29 in the longitudinal direction by φ, for example, by soldering materials 32 and 33. The shortest distance along the surface between the external electrodes 28 and 29 is configured to be longer than the shortest distance between the discharge spaces between the external electrodes 28 and 29. This is based on a structure formed to discharge only in the discharge space. When the excimer discharge lamp 21 is turned on, when a voltage is applied between the pair of external electrodes 28 and 29, discharge occurs between the external electrodes 28 and 29 via the discharge vessel 22. If the luminescent gas is argon (Ar) and sulphur hexafluoride (SF6), the gases are ionized to form argon ions and fluoride ions, forming an excimer molecule composed of argon-fluorine, and the light of 193 nm wavelength is The discharge capacitor 2 -18- 200933691 is emitted. In the longitudinal direction of the discharge vessel 22, the external electrodes 28, 29 are provided at positions away from the sealing member 24 and the cover member 23, whereby in the internal space 26 of the discharge vessel 22, the range of L3 located in the longitudinal direction The discharge of the range L4 from the end of the inner electrodes 28 and 29 to the seal member 424 did not occur. That is, the discharge vessel 22 has a surface portion on the one end side of the discharge vessel 22 that is not provided with the external electrodes 28, 29 over the entire circumference, and therefore, the phase 0 is compared with the internal space corresponding to the range of L3, and the L4 The internal space corresponding to the range is formed as a cooling zone with a lower temperature. Therefore, when a gas having a high chemical stability such as sulfur hexafluoride (SF6) is enclosed as a luminescent gas in the internal space 26 of the discharge vessel 22, L4 in the longitudinal direction of the discharge vessel 22 where no discharge occurs is caused. In the region, the reaction of fluoride ions ionized by the discharge back to the sulphur hexafluoride before ionization occurs. Therefore, in the internal space 26 of the discharge vessel 22, φ is suppressed from coming into contact with the fluoride ion between the end portions of the external electrodes 28 and 29 in the range of L3 in the longitudinal direction to the sealing member 24, and The reaction of the material constituting the sealing member 24 or the cover member 23 with fluorine ions is suppressed. There is no occurrence of a reaction between the halogen and the metal cover member, so that the amount of halogen is lowered, and the surface required for stable discharge sustaining does not occur as a discharge gap (the shortest distance between the discharge spaces between the external electrodes 28 and 29) S The shortest distance along the surface, and the discharge gap (the shortest distance between the discharge spaces between the external electrodes 28 and 29) <the distance between the external electrode and the metal cover. Further, in the excimer discharge lamp 21 of the present embodiment, as shown in Fig. 2, the illuminance is very stable in the region of the region -19-200933691 in which the neon (Ne) ratio is 90% or more, but in the neon (Ne) In the region where the ratio is extremely high (99.5% or more), the decrease in luminous efficiency becomes remarkable. Further, as shown in Fig. 3, the illuminance is very stable in the region where the 氦 (He) ratio is 90% or more, but in the 氦In the region where the (He) ratio is extremely high (99.5% or more), the decrease in luminous efficiency becomes remarkable. Further, in the excimer discharge lamp 21 of the present embodiment, the same experimental results as those obtained in Comparative Experiment 1 and Comparative Experiment 2 were also obtained. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a cross-sectional view of a cut surface of a tube axis of an excimer discharge lamp of the first embodiment of the invention, and a cut surface AA perpendicular to the tube axis. Sectional view. Fig. 2 is a graph showing the relationship between 氖(Ne) and the molar concentration of the fully enclosed gas and the luminous efficiency. Fig. 3 is a graph showing the relationship between 氦(He) and the molar concentration of the fully enclosed gas and the φ light efficiency. Figure 4 is a table showing the results of Comparative Experiment 1. Figure 5 is a table showing the results of Comparative Experiment 2. Fig. 6 is a cross-sectional view taken along the cut surface in the longitudinal direction of the excimer discharge lamp of the second embodiment, and a cross-sectional view taken along the cut surface A-A. [Explanation of main component symbols] 1 : Excimer discharge lamp -20- 200933691 Reactor 4: Cover member 6: Sealing material gas piping Internal space sealing part, 1 1 : External electrode, 13 : Pin, : 15 : Welding cons: Excimer discharge lamp: discharge capacitor: cover member: sealing material: gas piping: internal space: sealing part: plate-shaped external electrode: mesh external electrode, 31: pin, 3 3: welding consumable