1226977 i 玖、發明說明 【發明所屬之技術領域】 光微影成像法（Photolithography)已廣泛的使用於現 代大量複製精密圖案的各種產業。舉凡半導體積體電 路、微電子構裝基板、液晶顯示器面板及其重要零件的 彩色濾光片和印刷電路板等工業產品，都使用這個重要 製程。 [先前技術] 光微影成像法的內容一般而言包含一個光源，光罩 以及均勻塗佈一層光阻的基板工件。光源系統通常使用 紫外線燈源，如常用來提供3 00奈米以上波長的汞燈， 加上用以均勻放大照射面積及調整光線照射平行度的透 鏡和各式非平面反射鏡。光罩則以不會大量吸收工作波 長的材質製作，如石英玻璃板和其他金屬矽氧化物玻璃 以及較廉價的透明塑膠材質。光罩的一面繪有慾使之複 製於基板工件的圖案，使用時圖案面朝向基板工件上的 光阻層。當來自於光源的光線透過光罩上的圖案射入光 阻層時，光阻材料產生光化學變化，於是一個複製光罩 上圖案的潛像便建立於光阻層中。吾人一般利用光化學 變化對光阻的物、化性影響與未曝光的光阻區域作對比 的顯像或顯影的動作。一般而言，現代使用的光阻材料 系統多爲油性或非水溶性高分子組成，但是爲求避免顯 1226977 2 像時使用有機溶劑所以多設計以酸鹼水性分散或溶解來 顯像。以常用的負型自由基交連光阻爲例，曝光的光阻 區域會因紫外線產生自由基而引發帶有不飽和雙鍵的物 質產生連鎖的交連聚合反應。如果光阻系統內含適量的 羧酸基則未曝光的光阻區域可以被鹼性水溶液洗去，基 板面上只留下已曝光交連因而對鹼性水溶液較有抵抗性 的光阻圖案。在空氣中自由基交連反應會受氧氣阻撓而 降低活性。因此吾人可用對曝光製程無妨礙的介質來隔 絕空氣，舉例如美國專利6,1 65,5 445所揭露者，將塗有 光硬化樹脂的電路板置於水槽中使用紫外線光源自槽外 經由透明槽壁全面照射硬化。 若以常用的正型光阻爲例，曝光的光阻區域會因 紫外線產生羧酸基，因此可以鹼性水溶液溶解洗去而留 下未曝光且對鹼性水溶液較有抵抗性的光阻圖案。 在工業界的應用裡，顯影後的光阻圖案可以本身 就當作工件的一部分永久留在工件成品裡，例如用於印 刷電路板表面來保護電路的抗焊光阻綠漆（Solder Resist 或Solder Mask)、在1C載板中高密度電路間的感光性聚 亞醯胺介電質、用於電藕合元件（Charge Coupled Device，CCD)中的微透鏡，或者是彩色濾光片中使用的 紅綠藍三色光阻以及做黑色矩陣的黑色光阻。其他的光 阻大部分是在蝕刻或鍍膜及植入等製程時用以對光阻圖 案下方基板工件面的保護或隔絕。 光微影成像法在工業界中的利用主要依複製圖案 的尺寸精密度而有所不同。在光源系統上，高精細度至 1226977 3 微米以下尺寸的半導體電路圖案會要求昂貴的單色平行 光源與高準確性的透鏡與投射系統，而曝光面積也因而 受限。在數微米乃至數十微米以下尺寸的應用，如1C載 板中高密度電路、液晶顯示器面板及彩色濾光片等，則 使用相對較爲低廉的非平行光線與近接式（proximity)曝 光。近接式曝光如圖一所示，光源（1)自上提供相當均勻 的光線照向光罩（2)，光線透過光罩下方的圖案膜面（3) 經由空氣層（4)選擇性地投射在基板工件（6)上的光阻層 (5)。在這種系統裡，一般除了維持一定程度的光平行度 外並要求光源能夠相當均勻的投射在較大的面積以求經 濟性生產。光罩則使用大版面的石英或其他尺寸安定性 較佳的玻璃。基板工件則置於光罩下方並保持一定間隔 以防止接觸而使光罩膜面受損，而使用介面反射原理的 雷射測距與自動調整工件位置的控制裝置常用來確保固 定的間隔。一般而言間隔尺寸常在數十至數百微米範 圍。精密的雷射光學系統之外，也有使用較便宜的間隔 物來設定光罩與基板工件之間的間隔，例如美國專利 3,944,4 19中所揭露者。 光罩與光阻直接接觸的曝光方式也使用於傳統的 工業應用如抗焊光阻綠漆和印刷。直接接觸所產生的壓 痕及光罩膜面上來自光阻的黏著沾污是最主要的缺點。 但是由於減少了光罩與光阻之間空氣的間隔可以提昇解 析度。美國專利4,544,626便揭露了 一種將光罩與基板工 件置於裝有冷卻液體如水的槽中之後再將光罩與塗有光 反應高分子（Photopolymer)的基板工件以刮板壓合以求 1226977 4 光罩膜面與光阻密接的方法。該文獻並未教導使用間隔 物以控制圖案的轉移，而且該揭露教導將光罩置於水面 之下曝光谷易因爲水面的波動而產生光線在空氣與水的 介面不均勻折射引發的不均勻照度分佈。 【發明內容】 近接式曝光容許較大版面的曝光，因此提高工業 應用的量產效率。但是由於爭取大版面效益常要犧牲照 射光源的平行度，因此它在曝光成像的解析能力並未令 人滿意。原則上光線照射平行度愈高，曝光裝置的成本 也會增加。在曝光成像的過程中，當光線離開光罩射入 基板工件上的光阻層前須先經過間隔的空氣，因此當使 用非平行光源時，光線在光罩與空氣的界面會產生折 射。以空氣與光罩的折射率分別約略假設爲1.0與1.5 來計算，在光罩與基板工件之間的間隔爲1 50微米而光 源射向光罩的入射角爲5度時折射所產生的單邊圖案擴 張可以高達4.17微米。換言之，在光罩上若有10微米 寬的透光圖案則其下的光阻層表面實際曝光的區域將加 上兩旁各擴張4.17微米而成18.34微米寬。一般而言， 吾人可以用光罩圖案尺寸補償的方式來作補救。以此方 式吾人可在光·罩上開出遠低於1 0微米寬的透光圖案，並 調整顯像製程來配合取得10微米寬的光阻圖案。但是考 量工業應用裡整體實際圖案的複.雜性，這樣的妥協常未 能有效率達成。而這項缺失的改進便是本發明主要目的 1226977 5 之~° 另一方面，常用的正型或負型光阻在曝光機內使 用時會有昇華物或氣化物質產生並沾污於緊鄰的光罩 上。這項缺失也可藉由本發明而加以改善。 本發明乃一種改良的光微影成像曝光裝置與方 法’其主要特徵在於曝光時光罩與光阻之間充滿有一層 液體介質，而該介質的折射率大於空氣的折射率。本發 明裝置主要包含一個光源，光罩與塗佈有光阻層的基板 工件以及用以分隔兩者於一定間隔的裝置，以及一個供 輸流體介質於光罩與塗佈有光阻層的基板工件之間的機 構。 本發明使用一層液體介質在曝光時充滿於光罩與 光阻之間，使得自光罩投射進入光阻層的光線比較傳統 的曝光裝置有更小的折射角度，因而提昇了成像的解析 度。同時由於該液體介質的存在，排除了傳統製程中來 自光阻材料的昇華物或氣化物質對光罩產生污染的缺 失。以下則對本發明的實施方法作詳細的說明。 【實施方法】 本發明中的光源乃常用於一般近接式光微影成像 曝光裝置的光源。通常使用的有如汞燈，它產生特有的 波長，如主要輸出在40 5奈米、365奈米以及310奈米 左右波長的紫外線。光源系統另外包含用以均句放大照 射面積的各式透鏡及同時也調整光線照射平行度的非平 1226977 6 面反射鏡。相關的文獻可見於介紹光微影成像法的許多 書籍，舉例如 Wayne M. Moreau 所著的” Semiconductor Lithography” 。 本發明中曝光裝置內使用的光罩可以是工業界常 用的平板形式石英玻璃板和其他金屬矽氧化物玻璃板以 及較廉價的透明塑膠片材箄。在載有光罩圖案的這一 面，於必要時，也可以塗佈一層透光的保護膜用以隔絕 本發明中液體介質與光罩圖案接觸。 本發明中使用的液體介質可以是任何低黏度容易 流動的液體。它的折射率至少要高於空氣的折射率，且 以愈高者愈爲有效。它可以是高折射率，但在使用曝光 的波長範圍具有可接受的低吸收率者爲佳。舉例而言它 可以是單純的水也可以是溶有水溶性無機鹽類或有機物 質的水溶液。或者此液體介質也可以是非水性的其它有 機或無機的，常溫下液體或溶液。當考量液體介質與光 阻層接觸時，我們要選擇其與光阻物質在曝光製程接觸 的短暫過程中對光阻應有功能有可控制的影響者爲佳。 另外在考量液體介質對其所接觸的界面的潤著性能時， 吾人也可加入少量的表面活性劑。 光罩圖案與液體介質接觸時吾人也須考量長時使 用下對圖案物質是否會有侵_的風險。因此在必要時使 闱如前所述的透明保護膜於光罩圖案膜面上。保護膜可 以是各種惰性金屬或透明金屬氧化物，如氧化銦、氧化 錫及二者之混合物，利用通常的薄膜製程如蒸度或濺鍍 等方式施作於光罩圖案膜面上。這種薄膜厚度通常在數 1226977 7 十至數百奈米厚便足以具有保護作用並且具有一定程度 的光穿透性。保護膜也可以是一般常用的各類具成膜性 的高分子樹脂組成物。如常用的壓克力樹脂、環氧樹脂、 美耐皿樹脂、聚酯類樹脂、聚亞醯氨樹脂、硅酸樹脂等 眾多選擇。保護膜可以用常用的塗佈方法以溶液形式施 作於光罩圖案上再經烘烤硬化成膜。保護膜也可選擇使 用光敏性組成物，如常用的光敏性壓克力樹脂組成物， 經塗佈後曝光硬化成膜。我們同時也可將光敏性組成物 經由選擇性曝光硬化，使得保護膜層對應光罩圖案上非 透光的位置，在顯影後溶解部分厚度，而留下溝渠圖案。 該溝渠圖案，至少部分，以延展通至流體介質進入或吸 出口爲佳。溝渠深度則依液體介質層的黏度與厚度和光 罩版面大小及流體介質進出的設計而定。溝渠圖案的使 用有利於液體介質進出光罩與工件之間的間隔空隙。高 分子樹脂保護膜的膜厚原則上以液體介質對光罩圖案侵 蝕的可能性爲主要考量。一般而言厚度以不高於數微米 至數十微米的範圍爲佳。 本發明中使用的光罩上也可在適當的位置預置間 隔物用以控制光罩與光阻層之間的距離。間隔物所在的 位置可以對應於慾曝光之工件基板上其光阻已洗去或不 存在的位置，以免除間隔物與光阻層接觸而產生光阻屑 沾污。間隔物厚度可用以決定液體介質層的大小，進而 決定曝光的光線在射經光罩後投射於光阻層上的位置。 適當的間隔物可以選自硬質的橡膠或塑膠材料或是不易 傷及所接觸的工件基板的其他金屬或無機物。原則上， 1226977 8 間隔物厚度以愈小爲佳如此整個曝光裝置的解析度會提 高。另一方面，吾人也可使用傳統的近接式光微影成像 曝光裝置中常用的雷射光學系統控制間隔。 本發明中流體介質與均勻塗佈一層光阻的基板工 件直接接觸。一般常用於工業界的正型或負型光阻皆適 用於本系統。常用的正型光阻可以醌二疊氮 (Diazoqinnone)/酚醛樹脂系統的混合物組成爲代表。常 用的負型光阻可以利用壓克力自由基進行光敏性交連反 應的各種高分子樹脂混合物爲代表。適用於本發明的各 種具成膜性的工業用正、負型光阻材料系統於Deforest 所著的 ”Photoresist Materials and Processing”一 書皆可 見詳細的說明。基板工件原則上以平整的板材爲爲適當。 本發明裝置在使用時，如圖二中所示乃將光源（1)、圖案 膜面（3)背對光源的光罩（2)、液體介質層（7)以及塗有光 阻層（5)的基板工件（6)依序排置。前述光罩與基板工件也 可以垂直於水平面來安置用以改善光罩與基板工件受重 力影響，於無支撐處下垂的現象。 液體介質層的導入於光罩與工件基板之間的各種 方法對於熟悉此工藝的人士是可以很輕易來瞭解的。舉 例來說，如圖三所示，吾人可以在光罩（2)周緣的光罩基 座（11)的表面上設置高於光罩面的具彈性的平整框狀物 (9)並在其與光罩邊緣之間預留供液體介質自基座進出 的開口（10)。當固定在工件基座（8)上的基板工件向光 罩壓著後，液體介質务声空氣可以經由圖中兩個開口（丄〇) 之一，以加壓流入或減壓吸入的方式，或者藉由毛細現 1226977 9 象充滿塗有光阻層（6)的工件基板（5)與光罩（2)之間的空 間，其流動方式如圖三中空心箭頭所示。在此例中平整 框狀物（9)同時也用以當做控制光罩與工件基板之間距 離的間隔物。在曝光完成後，空氣可以經由兩個開口（ 1 0) 之一配合拉開光罩基座（11)與工件基座（8)至框狀物（9) 原高度的距離的機械動作進入工件基板（5)與光罩（2)之 間的空間，使得工件基板（5)可以輕易取出。液體介質則 在空氣進入時自另一開口排出。 以上說明完整揭露了本發明的內容，對熟悉本工 藝的人士皆可據以實施。惟本發明內涵並不只限於本詳 細內容說明中所述及者。 【圖式簡單說明】 圖一：傳統曝光方式簡圖，其中的光源（1)自上提 供相當均勻的光線照向光罩（2)，光線透過光罩下方的圖 案膜面（3)經由空氣層（4)選擇性地投射在基板工件（6)上 的光阻層（5)。 圖二：本發明曝光方式示意圖，其中將光源（1)、 圖案膜面（3)背對光源的光罩（2)、液體介質層（7)以及塗 有光阻層（5)的基板工件（6)依序排置進行曝光。 圖三：本發明曝光裝置簡圖，其中液體介質經由 兩個開口（10)之一流入並充滿塗有光阻層（6)的工件基板 (5)與光罩（2)之間的空間。當作間隔物的平整框狀物（9) 設置於光罩基座（11)與工件基座（8)之間。1226977 i 发明 Description of the invention [Technical field to which the invention belongs] Photolithography has been widely used in various industries that reproduce a large number of precision patterns in modern times. For example, industrial products such as semiconductor integrated circuits, microelectronics mounting substrates, liquid crystal display panels and their important parts, color filters and printed circuit boards, all use this important process. [Prior art] The content of the photolithography method generally includes a light source, a photomask, and a substrate workpiece uniformly coated with a photoresist. The light source system usually uses an ultraviolet light source, such as a mercury lamp commonly used to provide wavelengths above 300 nm, plus a lens and various non-planar mirrors to uniformly enlarge the irradiation area and adjust the parallelism of light irradiation. The photomask is made of materials that do not absorb much of the working wavelength, such as quartz glass plates and other metal silicon oxide glasses, as well as cheaper transparent plastic materials. One side of the photomask is painted with a pattern to be copied on the substrate workpiece, and the pattern side faces the photoresist layer on the substrate workpiece when in use. When light from the light source enters the photoresist layer through the pattern on the photomask, the photoresist material produces a photochemical change, so a latent image that replicates the pattern on the photomask is created in the photoresist layer. I generally use the action of development or development in which the photochemical change affects the photoresist's physical and chemical properties in comparison with the unexposed photoresist area. Generally speaking, modern photoresist material systems are mostly composed of oily or water-insoluble polymers. However, in order to avoid the use of organic solvents during image development, it is often designed to disperse or dissolve in acidic and alkaline water for development. Taking the commonly used negative radical cross-linked photoresist as an example, the exposed photoresist area will cause free-radical generation of ultraviolet rays to trigger chain cross-linking polymerization of substances with unsaturated double bonds. If the photoresist system contains an appropriate amount of carboxylic acid groups, the unexposed photoresist area can be washed away by the alkaline aqueous solution, and only the exposed photoresist pattern on the substrate surface that is more resistant to the alkaline aqueous solution can be left. Free radical cross-linking reactions in the air can be hindered by oxygen and reduce activity. Therefore, we can use a medium that does not interfere with the exposure process to isolate the air. For example, as disclosed in US Patent 6,1 65,5 445, the circuit board coated with light hardening resin is placed in a water tank, and an ultraviolet light source is used to transparently pass from the outside of the tank. The groove wall is fully hardened by irradiation. If a commonly used positive type photoresist is used as an example, the exposed photoresist area will generate carboxylic acid groups due to ultraviolet rays, so it can be dissolved and washed away in an alkaline aqueous solution to leave an unexposed photoresist pattern that is more resistant to the alkaline aqueous solution. . In industrial applications, the developed photoresist pattern can be left in the finished product as a part of the workpiece itself, such as solder resist green paint (Solder Resist or Solder) used to protect the surface of printed circuit boards. Mask), photosensitive polyimide dielectric between high-density circuits in 1C carrier boards, microlenses used in Charge Coupled Device (CCD), or red used in color filters Green and blue photoresistors and black photoresistors for black matrix. Most other photoresists are used to protect or isolate the workpiece surface of the substrate under the photoresist pattern during processes such as etching or coating and implantation. The use of photolithography in the industrial world depends mainly on the dimensional accuracy of the copied pattern. In the light source system, high-resolution semiconductor circuits with a size of less than 1226977 3 micrometers will require expensive monochrome parallel light sources and highly accurate lenses and projection systems, and the exposure area will be limited. In applications with sizes of several microns or even tens of microns, such as high-density circuits in 1C substrates, liquid crystal display panels, and color filters, relatively inexpensive non-parallel light and proximity exposure are used. Proximity exposure is shown in Figure 1. The light source (1) provides fairly uniform light to the mask (2) from above. The light passes through the pattern film surface (3) under the mask and is selectively projected through the air layer (4). A photoresist layer (5) on a substrate workpiece (6). In such a system, in addition to maintaining a certain degree of light parallelism, it is required that the light source can be projected fairly evenly over a large area for economical production. The mask uses large-format quartz or other glass with better stability. The substrate workpiece is placed under the mask and kept at a certain interval to prevent contact and damage the mask film surface. The laser ranging using the interface reflection principle and the control device that automatically adjusts the position of the workpiece are often used to ensure a fixed interval. In general, the gap size is usually in the range of tens to hundreds of microns. In addition to sophisticated laser optical systems, there are also cheaper spacers for setting the gap between the mask and the substrate workpiece, such as disclosed in U.S. Patent No. 3,944,419. Exposure methods where the photomask and photoresist are in direct contact are also used in traditional industrial applications such as solder resist green paint and printing. The indentation caused by direct contact and the adhesion and contamination from the photoresist on the mask film surface are the main disadvantages. However, the resolution can be improved by reducing the air separation between the mask and the photoresist. U.S. Patent No. 4,544,626 discloses a method in which a photomask and a substrate workpiece are placed in a tank containing a cooling liquid such as water, and then the photomask and the substrate workpiece coated with a photopolymer are laminated with a scraper to obtain 1226977 4 A method for tightly bonding a photomask film surface to a photoresist. This document does not teach the use of spacers to control the transfer of patterns, and the disclosure teaches that placing a photomask under the surface of the water to expose the valley is prone to uneven illumination caused by uneven refraction of light at the air-water interface due to fluctuations in the water surface distributed. [Summary of the Invention] Proximity exposure allows larger layout exposures, thus improving mass production efficiency for industrial applications. However, the resolution of the exposure image is not satisfactory because the parallelism of the illumination light source is often sacrificed for the benefit of large layouts. In principle, the higher the parallelism of light irradiation, the higher the cost of the exposure device. In the process of exposure imaging, when the light leaves the photomask and enters the photoresist layer on the substrate, it must pass through the space. Therefore, when a non-parallel light source is used, the light will be refracted at the interface between the photomask and the air. Based on the assumption that the refractive indices of air and the mask are approximately 1.0 and 1.5, respectively, the unit generated by refraction when the distance between the mask and the substrate workpiece is 150 microns and the incident angle of the light source to the mask is 5 degrees. The edge pattern expansion can be as high as 4.17 microns. In other words, if there is a 10 micron wide light transmission pattern on the reticle, the area actually exposed on the surface of the photoresist layer underneath will be expanded by 4.17 micrometers on both sides to make it 18.34 micrometers wide. In general, we can use the compensation of the size of the mask pattern to remedy. In this way, we can open a light transmission pattern on the photomask that is much less than 10 microns wide, and adjust the development process to obtain a 10 micron wide photoresist pattern. However, considering the complexity and complexity of the overall actual pattern in industrial applications, such compromises often cannot be reached efficiently. And this missing improvement is the main purpose of the present invention, 1226977 5 ~ ° On the other hand, the commonly used positive or negative photoresist will produce sublimates or vaporized substances when used in the exposure machine and contaminate the immediate vicinity. Mask. This deficiency can also be improved by the present invention. The present invention is an improved photolithographic imaging exposure device and method ', which is mainly characterized in that a layer of a liquid medium is filled between a photomask and a photoresist during exposure, and the refractive index of the medium is greater than that of air. The device of the invention mainly comprises a light source, a photomask and a substrate workpiece coated with a photoresist layer, a device for separating the two at a certain interval, and a substrate for supplying a fluid medium between the photomask and the photoresist layer. Mechanism between workpieces. The invention uses a layer of liquid medium to fill the space between the photomask and the photoresist during exposure, so that the light projected from the photomask into the photoresist layer has a smaller refraction angle than a conventional exposure device, thereby improving the imaging resolution. At the same time, due to the existence of the liquid medium, the defect that the sublimation or gasification substance from the photoresist material in the traditional process causes pollution to the photomask is eliminated. Hereinafter, the implementation method of the present invention will be described in detail. [Implementation method] The light source in the present invention is a light source commonly used in a general proximity photolithography imaging exposure device. Commonly used is a mercury lamp, which generates unique wavelengths, such as ultraviolet light that mainly outputs wavelengths around 40 5 nm, 365 nm, and 310 nm. The light source system also includes a variety of lenses to enlarge the illuminated area uniformly, and a non-planar 1226977 6-face mirror that also adjusts the parallelism of light irradiation. Related literature can be found in many books on photolithography, such as "Semiconductor Lithography" by Wayne M. Moreau. The photomask used in the exposure device in the present invention may be a flat-plate quartz glass plate and other metal silicon oxide glass plates commonly used in the industry, and a relatively inexpensive transparent plastic sheet. On the side carrying the mask pattern, if necessary, a light-transmitting protective film may also be applied to isolate the liquid medium in the present invention from contact with the mask pattern. The liquid medium used in the present invention may be any liquid having a low viscosity and flowing easily. Its refractive index is at least higher than that of air, and the higher is more effective. It can be a high refractive index, but preferably has an acceptable low absorptance in the wavelength range where the exposure is used. For example, it may be pure water or an aqueous solution in which water-soluble inorganic salts or organic substances are dissolved. Or the liquid medium may be other organic or inorganic non-aqueous, liquid or solution at normal temperature. When considering the contact between the liquid medium and the photoresist layer, it is better to choose those that have a controllable effect on the photoresist function during the short process of contact with the photoresist material during the exposure process. In addition, when considering the wettability of the liquid medium to the interface it contacts, we can also add a small amount of surfactant. When the photomask pattern is in contact with the liquid medium, we must also consider whether there is a risk of invasion of the pattern material under long-term use. Therefore, when necessary, a transparent protective film as described above is placed on the mask pattern film surface. The protective film may be various inert metals or transparent metal oxides, such as indium oxide, tin oxide, and a mixture of the two, and is applied to the surface of the mask pattern film by a common thin film process such as evaporation or sputtering. The thickness of such a film is usually in the range of 1,226,977 7 to several hundred nanometers, which is sufficient for protection and has a certain degree of light transmission. The protective film may also be various commonly used polymer resin compositions having film-forming properties. Such as commonly used acrylic resin, epoxy resin, melamine resin, polyester resin, polyurethane resin, silicone resin, and many other choices. The protective film can be applied to the photomask pattern as a solution by a common coating method, and then cured and formed into a film. The protective film can also optionally use a photosensitive composition, such as a commonly used photosensitive acrylic resin composition, which is exposed to harden to form a film after coating. At the same time, we can also harden the photosensitive composition through selective exposure, so that the protective film layer corresponds to the non-light-transmitting position on the reticle pattern. After development, it dissolves a part of the thickness, leaving a trench pattern. The trench pattern is, at least in part, preferably extended to the fluid medium inlet or outlet. The depth of the trench is determined by the viscosity and thickness of the liquid medium layer, the size of the mask layout, and the design of the fluid medium in and out. The use of a trench pattern facilitates the passage of liquid medium into and out of the mask and the workpiece. In principle, the thickness of the protective film of the high molecular resin is based on the possibility of the liquid medium eroding the mask pattern. Generally, the thickness is preferably in the range of not more than several micrometers to several tens of micrometers. The photomask used in the present invention can also be provided with spacers at appropriate positions to control the distance between the photomask and the photoresist layer. The position of the spacer may correspond to the position where the photoresist on the substrate of the workpiece to be exposed has been washed away or does not exist, so as to avoid the contamination of the photoresist chip due to the contact between the spacer and the photoresist layer. The thickness of the spacer can be used to determine the size of the liquid medium layer, and then to determine the position where the exposed light is projected on the photoresist layer after passing through the photomask. Appropriate spacers can be selected from hard rubber or plastic materials or other metals or inorganics that do not easily damage the substrate of the workpiece in contact. In principle, the smaller the thickness of the 1226977 8 spacer is, the better the resolution of the entire exposure device will be. On the other hand, we can also control the interval using the laser optical system commonly used in conventional proximity photolithography imaging exposure devices. In the present invention, the fluid medium is in direct contact with a substrate workpiece which is uniformly coated with a layer of photoresist. Generally used in the industry are positive or negative photoresistors suitable for this system. Commonly used positive photoresists can be represented by a mixture of quinonediazide / phenol resin systems. Commonly used negative photoresists can be represented by various polymer resin mixtures that use acrylic radicals for photosensitizing crosslinking reactions. A variety of film-forming industrial positive and negative photoresist material systems suitable for use in the present invention are described in detail in the book "Photoresist Materials and Processing" by Deforest. In principle, a flat plate material is suitable for the substrate workpiece. When the device of the present invention is in use, as shown in FIG. 2, the light source (1), the pattern film surface (3) face away from the light source cover (2), the liquid medium layer (7), and the photoresist layer (5 ) The substrate workpieces (6) are arranged in order. The aforementioned photomask and substrate workpieces can also be placed perpendicular to the horizontal plane to improve the phenomenon that the photomask and substrate workpieces are sagging at unsupported locations due to gravity. Various methods of introducing the liquid medium layer between the photomask and the substrate of the workpiece can be easily understood by those familiar with the process. For example, as shown in FIG. 3, we can set a flat and elastic frame (9) on the surface of the mask base (11) on the periphery of the mask (2) above the mask surface. An opening (10) is reserved between the edge of the mask and the edge of the photomask for the liquid medium to enter and exit from the base. When the substrate workpiece fixed on the workpiece base (8) is pressed against the photomask, the liquid medium air can be inhaled under pressure or inhaled through one of the two openings (丄 〇) in the figure. Or, the capillary is filled with the 1226977 9 image filled with the space between the workpiece substrate (5) and the photomask (2) coated with a photoresist layer (6), and the flow mode is shown by the hollow arrow in Figure 3. In this example, the flat frame (9) is also used as a spacer to control the distance between the photomask and the workpiece substrate. After the exposure is completed, the air can enter the workpiece through one of the two openings (10) through the mechanical action of pulling away the mask base (11) and the workpiece base (8) to the original height of the frame (9). The space between the substrate (5) and the photomask (2) allows the workpiece substrate (5) to be easily taken out. The liquid medium is discharged from another opening when air enters. The above description completely discloses the content of the present invention, and can be implemented by anyone familiar with the process. However, the content of the present invention is not limited to those described in the detailed description. [Brief description of the figure] Figure 1: A schematic diagram of a traditional exposure method, in which the light source (1) provides a fairly uniform light from the top to the mask (2), and the light passes through the pattern film surface (3) under the mask through the air The layer (4) selectively projects a photoresist layer (5) on the substrate workpiece (6). Figure 2: Schematic diagram of the exposure method of the present invention, in which the light source (1), the pattern film surface (3) are facing away from the light source cover (2), the liquid medium layer (7), and the substrate workpiece coated with the photoresist layer (5) (6) Exposure is performed in order. Figure 3: A schematic diagram of an exposure device according to the present invention, in which a liquid medium flows into one of two openings (10) and fills a space between a work substrate (5) coated with a photoresist layer (6) and a photomask (2). A flat frame (9) as a spacer is set between the mask base (11) and the work base (8).