1253107 九、發明說明： 【發明所屬之技術領域】 本發明係關於一種半導體製程技術，特別是關於一種改良之濕 反式微影技術以及其所使用的濕浸介質。習知技藝中常用來阻擋 光酸擴散的上保護層可以在本發明中被省略。 【先前技術】 微影製程技術在ic製造中一直扮演著舉足輕重的角色，隨著 IC產品技術需求的提升，微影技術也需不斷地提高解析度以製作 更微小的特徵尺寸。 如遠行業者所熟知，光學微影系統的解析度⑹可以下面的方程 式表示： ro^kj λ/ΝΑ ⑴ 其中λ疋光學微影系統操作時所使用的光波長，ΝΑ代表數值 孔徑’而數值孔徑又可用下面的方程式表示： NA-n sin θ〇 ⑺ 其中η即代表光線光學微影系統的光學透鏡與晶圓之間的介質 的折射率(refraction index)。 l253l〇7 ^由前述方程式可知，要提高解析度通常可以採下列幾種方法進 仃·（1)縮紐光源波長λ，例如從較早使用的g_Hne汞燈光源、193 示米準分子雷射光源到157奈米，甚至發展中的極短紫外線光；(幻 采用％析度加強技術(res〇luti〇n enhancement把冰邮職），例如相位 移光罩、偏軸照明等；⑶經由改善光學系統加大數值孔徑(NA)。 ^濕浸式微影技術則提供另一種提高解析度的方法。所謂濕浸式 _ U〃磁術乃將光學透鏡與光阻之間的缝介質以越取代之技 術、’利用光通過流體介質後，縮短光源波長以提升其解析度，公 式為λ’=λ/η(λ’為通過流體介質後的波長；λ為在空氣中的波長；n 為流體介質的折射率）。絲目前193·奈米波長曝光機台中，在光 源與晶圓之間加入純水為介質(水的折射率約為h43)，其波長可縮 短為132奈米。 然而濕浸式技術仍有幾項關鍵因素待克服，例如純水與光阻交 _互作用以及水中微泡的控制等等。若濕浸式技術能研發成功，將 可以繼續使用193奈米曝光機，進行65奈米以及幻奈米等先進 製程研發，而可以省下可觀的曝光機的設備成本支出。 【發明内容】 本發明之主要目的在提供-種改良之濕浸式微影技術，以解決 習知技藝中光阻照光產生光酸與其對濕浸介質所造成的影響。 6 1253107 、…本發明提供-種應用在濕浸式微影製程中的濕浸介質，其中該 濕浸介質係填滿在由-步進機的成像透鏡的前表面與—光阻層的 上表面所定義的間格空隙中’其特徵在於該濕浸介質的阳值^ 該光阻層白勺pH值匹配，藉此避免由於該光阻層照光產生光酸由:亥 光阻層滲出職濕浸介質情產生的影響。該光阻層係直接接觸 該濕浸介質，而可以省略一上保護層。 為了使f審查委員能更近-步了解本發明之特徵及技術内 容：請參_下錢本發明之詳細朗與_。然而所附圖式僅 供参考與輔助說棚’並非用來對本發明加以限制者。 【實施方式】 本發明關於-種改良之濕浸式微影技術，其中特別涉及一種非 中性的濕浸介質的制，目的在解決習知技藝巾光阻照光產生光 酸(photo acid generator，PAG)與其對濕浸介質所造成的影響，藉此 有效地延長ArF步進機台在半導體製程中的使用極限。下文中， 所谓的「非中性」指的是該濕浸介質的pH值不等於7 〇。 凊參閱第1圖’其纟會示的是本發明較佳實施例之剖面示意圖。 如第1圖所示，在-晶圓轉台(圖未示)上放置有，晶圓或半導體 基材10 ’其中半導體基材1〇具有一上表面u，其上設有一層抗 反射膜12 ’在抗反射膜12上形成有一光阻層14。根據本發明之 較佳實施例，光阻層14係為一正光阻，但不限於此。較重要的是， 1253107 光阻層14具有在照光時產生光酸之特性，前述的光在&實施例中 指的是ArF 193奈米準分子雷射光。光線經由光罩6〇的透光區域 601照射至光阻層14，由於光阻層14在照光時產生大量光酸，並 滲入與其接觸的濕浸介質，例如純水中，因而改變了純水的pH值 以及成像品質。 根據本發明之較佳實施例，在光阻層14之上為步進機台的成 •像透鏡2〇，其與光阻層14接近並列配置’其中成像透鏡20具有 一前表面19，其與光阻層14的上表面14定義出間隔空隙18。在 此間隔空隙18中填滿有非中性的濕浸介質16。為解決前述的光阻 層14在照光啦生A量光酸’麟人與其接觸的濕浸介質的問 題’本發明的非中性的濕浸介# 16_調整配方使其pH值與光 阻層14的PH值相匹配，如此使得在光阻層14照光產生光酸後， 不會因為光酸滲入，改變濕浸介質16的pH值，而影響成像品質。 其中’姐層14的pH值可以由光阻供應商提供，或者在光阻呈 液態時進行量測。 —此外，别述的非中性的濕浸介質16可以是包含有緩衝系統的 W液例如由鹽酸'氯化钟等緩衝溶液系統，藉此在整個微影過 程中’讓濕浸介質16保持在pH值固定的狀態。值得注意的是， 本發明由於採用非中性的濕浸介質16，因此可以省略掉習知技藝 令常覆於光阻表面用來阻擔絲擴散的上保護層㈣⑽〇 ,也因此 可以進-步簡化製程步驟並節省成本。 l253l〇7 以上所述僅為本發明之較佳實施例’凡依本發明申請專利範圍 所做之均等變化與修飾，皆應屬本發明之涵蓋範圍。 【圖式簡單說明】 第i圖!會示的是本發明較佳實施例之剖面示意圖。 .【主要元件符號說明】 上表面 上表面 濕浸介質 前表面 光罩. 10 半導體基材 12 抗反射膜 14 光阻層 18 間格空隙 20 成像透鏡 601透光區域1253107 IX. DESCRIPTION OF THE INVENTION: TECHNICAL FIELD OF THE INVENTION The present invention relates to a semiconductor process technology, and more particularly to an improved wet trans lithography technique and a wet immersion medium therefor. Upper protective layers commonly used in the prior art to block photoacid diffusion can be omitted in the present invention. [Prior Art] The lithography process technology has always played a pivotal role in ic manufacturing. As the technical requirements of IC products increase, lithography technology also needs to continuously improve the resolution to produce smaller feature sizes. As is well known to those skilled in the art, the resolution of the optical lithography system (6) can be expressed by the following equation: ro^kj λ/ΝΑ (1) where the wavelength of light used in the operation of the λ疋 optical lithography system, ΝΑ represents the numerical aperture 'and the value The aperture can be expressed by the following equation: NA-n sin θ 〇 (7) where η represents the refractive index of the medium between the optical lens of the ray optical lithography system and the wafer. L253l〇7 ^ From the above equation, we can see that the following methods can be used to improve the resolution. (1) The wavelength of the light source is λ, for example, from the g_Hne mercury light source used earlier, 193 meters excimer laser Light source to 157 nm, even the development of extremely short ultraviolet light; (magic using % resolution enhancement technology (res〇luti〇n enhancement to ice post), such as phase shift mask, off-axis illumination, etc.; (3) through improvement The optical system increases the numerical aperture (NA). The wet immersion lithography technology provides another way to improve the resolution. The so-called wet immersion _ U 〃 magnet is to replace the sewing medium between the optical lens and the photoresist. The technology, 'use light to pass through the fluid medium, shorten the wavelength of the light source to improve its resolution, the formula is λ' = λ / η (λ' is the wavelength after passing through the fluid medium; λ is the wavelength in the air; n is the fluid The refractive index of the medium. In the current 193 nm nanometer exposure machine, pure water is used as the medium between the light source and the wafer (the refractive index of water is about h43), and the wavelength can be shortened to 132 nm. Immersion technology still has several key factors to be Overcome, for example, the interaction between pure water and photoresist _ interaction and the control of microbubbles in water, etc. If the wet immersion technology can be successfully developed, it will continue to use the 193 nm exposure machine for advanced 65 nm and Magic Nano. Process development, which can save considerable equipment cost of the exposure machine. SUMMARY OF THE INVENTION The main object of the present invention is to provide an improved wet immersion lithography technology to solve the photo-induced photo-acid and its photo-acid Effect on wet immersion media. 6 1253107, The present invention provides a wet immersion medium for use in a wet immersion lithography process, wherein the wet immersion medium is filled in front of an imaging lens of a stepper The surface and the interstitial space defined by the upper surface of the photoresist layer are characterized in that the positive value of the wet dip medium is matched with the pH value of the photoresist layer, thereby avoiding photoacid generation due to the photo-resist layer illumination. The effect of the invention is: the photoresist layer is directly exposed to the wet immersion medium, and the upper protective layer can be omitted. In order to enable the review committee to be closer to the present invention Features and technology容容: Please refer to the detailed description of the invention and the present invention. However, the drawings are for reference only and are not intended to limit the invention. [Embodiment] The present invention relates to a modified wet dip The lithography technology, in particular, relates to a non-neutral wet immersion medium, which aims to solve the effect of photo acid generator (PAG) and its effect on wet immersion medium by conventional art towel Effectively extend the use limit of the ArF stepper in the semiconductor manufacturing process. Hereinafter, the term "non-neutral" means that the pH of the wet dip medium is not equal to 7 〇. 凊 Refer to Figure 1 Shown is a schematic cross-sectional view of a preferred embodiment of the present invention. As shown in Fig. 1, a wafer or semiconductor substrate 10 is placed on a wafer turntable (not shown), wherein the semiconductor substrate 1 has a The upper surface u is provided with an anti-reflection film 12'. A photoresist layer 14 is formed on the anti-reflection film 12. In accordance with a preferred embodiment of the present invention, the photoresist layer 14 is a positive photoresist, but is not limited thereto. More importantly, the 1253107 photoresist layer 14 has the property of generating photoacid upon illumination, and the aforementioned light in the & embodiment refers to ArF 193 nm excimer laser light. The light is irradiated to the photoresist layer 14 through the light-transmitting region 601 of the reticle 6 ,. Since the photoresist layer 14 generates a large amount of photoacid during illumination, and penetrates into a wet immersion medium, such as pure water, which is in contact therewith, the pure water is changed. pH and imaging quality. According to a preferred embodiment of the present invention, above the photoresist layer 14, the image forming lens of the stepper stage is disposed adjacent to the photoresist layer 14 in a juxtaposed configuration, wherein the imaging lens 20 has a front surface 19, A spacing gap 18 is defined with the upper surface 14 of the photoresist layer 14. The spacer voids 18 are filled with a non-neutral wet dip medium 16. In order to solve the problem of the aforementioned photoresist layer 14 in the light immersion A amount of photoacid 'Lin people contact with the wet immersion medium' of the present invention, the non-neutral wet immersion medium # 16_ adjust the formula to make its pH and photoresist The pH of the layer 14 is matched such that after the photoresist layer 14 is illuminated to produce photoacid, the pH of the wet immersion medium 16 is not changed by the penetration of photoacids, thereby affecting the image quality. The pH of the 'sister layer 14' can be provided by the photoresist supplier or measured when the photoresist is in a liquid state. In addition, the non-neutral wet immersion medium 16 described may be a W solution containing a buffer system such as a buffer solution system such as a hydrochloric acid chlorination clock, thereby allowing the wet immersion medium 16 to remain throughout the lithography process. In a state where the pH is fixed. It is to be noted that, since the present invention employs a non-neutral wet dip medium 16, it is possible to omit the conventional protective layer (4) (10) which is often applied to the surface of the photoresist to resist the diffusion of the filament, and thus can be advanced. Steps simplify process steps and save costs. The above descriptions of the preferred embodiments of the present invention are intended to be within the scope of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS Fig. i is a schematic cross-sectional view showing a preferred embodiment of the present invention. [Main component symbol description] Upper surface Upper surface Wet immersion medium Front surface Photomask. 10 Semiconductor substrate 12 Anti-reflection film 14 Photoresist layer 18 Space gap 20 Imaging lens 601 Translucent area