569305 五、發明說明（1) 發明所屬之技術領域 -本發明係關於半導體製程，尤指一種微影製程，可使 半導體元件之臨界尺寸（critical dimension，簡稱為CD) 縮小，同時改善C D縮小之均勻度（u n i f o r m i t y )。 先前技術 隨著半導體製造技術的發展，積體電路的尺寸也越來 越小。在積體電路的製造過程中，最關鍵之技術莫過於所 謂的微影製程（lithography)，其肩負著將光罩上圖案精 確地轉印至晶圓上不同元件層之重要責任，同時，微影製 程所使用的曝光光源波長亦可決定半導體元件所能達到的 最小尺寸。在微影製程過程中，微小接觸洞（contact h ο 1 e )的成形顯然要比在晶圓上形成細線等其它圖案要困 難許多。目前，雖已有部份的研究提出幾種方法可將元件 的臨界尺寸（C D ) ’例如接觸洞的C D ’進一步縮小至曝光光 源之波長極限以下，包括由日本三菱公司所提出之RELACS 法、由韓國三星公司所提出之熱流法（therma 1 f 1 〇w)、以 及由日本T 0 K公司所提出之S A F I E R法，然而，上述這些改 良方法皆會遇到均勻度不佳之問題。舉例來說，在接觸洞 圖案較密集之區域以及接觸洞圖案較疏之區域所得到的接 觸洞尺寸縮小幅度即有明顯差異’使得元件的可靠度降 低。569305 5. Description of the invention (1) The technical field to which the invention belongs-the present invention relates to semiconductor processes, especially a lithographic process, which can reduce the critical dimension (CD) of semiconductor elements, and improve the reduction of CD Uniformity. Prior art With the development of semiconductor manufacturing technology, the size of integrated circuits has become smaller and smaller. In the manufacturing process of integrated circuits, the most critical technology is the so-called lithography, which shoulders the important responsibility of accurately transferring the pattern on the photomask to different component layers on the wafer. The wavelength of the exposure light source used in the filming process can also determine the minimum size that the semiconductor device can achieve. In the lithography process, the formation of micro contact holes (contact h ο 1 e) is obviously more difficult than forming other patterns such as thin lines on the wafer. At present, although some studies have proposed several methods to further reduce the critical dimension (CD) of components, such as the CD of contact holes, below the wavelength limit of the exposure light source, including the RELACS method proposed by Japan's Mitsubishi Corporation, The heat flow method (therma 1 f 1 0w) proposed by South Korea's Samsung Corporation, and the SAFIER method proposed by Japan's T 0 K Corporation. However, these improved methods all suffer from poor uniformity. For example, there is a significant difference in the reduction in contact hole size obtained in areas with dense contact hole patterns and areas with sparse contact hole patterns, which reduces the reliability of the device.
第6頁 569305 五、發明說明（2) 請參閱圖一，圖一為習知縮小元件CD方法之流程圖。 以下即藉由圖一說明由日本三菱公司所提出之RELACS法 (RELACS為 Resolution Enhancement Lithography Assisted by Chemical Shrink之縮寫）。首先，如步驟 1 所示，經由照光可產生酸之第一光阻層被塗佈於一半導體 基底上。第一光阻層約0 · 7微米厚，且一般需經過7 0°C至 100°C約1分鐘左右之預烤（pre-baking)處理。光線經由一 預定光罩圖案對第一光阻層進行曝光。曝光光源可以為汞 燈（mercury lamp)所發出之g-l ine或i —1 ine光線，其曝照 時間約對應於2 0 0 m J / c m之單位能量。有時為了增加解析 度，曝光後之第一光阻層可再經過一道1 〇 (TC至1 6 0°c後烤 (post exposure baking)處理。接著進行顯影，利用例如 2 wt%之 TMAH(tetra-methyl-ammonium hydroxide)稀釋水 溶液將第一光阻層經過光線照射過之區域溶解去除，產生 一第一蝕刻遮罩圖案。 接著如步驟2所示，含有可與第一光阻層發生架橋連 結（cross-1 inking)反應之第二光阻層被覆蓋在第一光阻 =上。、第二光阻層内含有在酸的存在下可發生架橋連結反 了之成分’且可溶解於無法溶解第一光阻層之溶劑中。第 ΐ所光干阻層對可丰接/Λ8Γ下進行一道預烤製程。㈣如步驟 Γ,導體基底加熱’以使先前所產生的酸得以擴 月 阻層各角落以及第二光阻層，俾使在第一光阻Page 6 569305 V. Description of the invention (2) Please refer to FIG. 1. FIG. 1 is a flowchart of a conventional method for reducing a component CD. The following is an illustration of the RELACS method (RELACS is the abbreviation of Resolution Enhancement Lithography Assisted by Chemical Shrink) proposed by Mitsubishi Corporation in Japan with reference to FIG. First, as shown in step 1, a first photoresist layer capable of generating an acid through light irradiation is coated on a semiconductor substrate. The first photoresist layer is about 0.7 microns thick, and generally requires a pre-baking process at about 70 ° C to 100 ° C for about 1 minute. The light is exposed to the first photoresist layer through a predetermined mask pattern. The exposure light source can be g-ine or i-ine light emitted by a mercury lamp, and the exposure time corresponds to a unit energy of 2000 m J / cm. Sometimes in order to increase the resolution, the first photoresist layer after exposure may be subjected to a post-baking treatment of 10 (TC to 160 ° C). Then, development is performed using, for example, 2 wt% TMAH ( tetra-methyl-ammonium hydroxide) diluted aqueous solution to dissolve and remove the first photoresist layer through the area irradiated by the light, to generate a first etching mask pattern. Then, as shown in step 2, the first photoresist layer is bridged with the first photoresist layer. The second photoresist layer of the cross-1 inking reaction is covered on the first photoresistor. The second photoresist layer contains a component that can undergo cross-linking in the presence of an acid 'and is soluble in The first photoresist layer cannot be dissolved in the solvent. The first photoresist layer is subjected to a pre-baking process under abundance / Λ8Γ. In step Γ, the conductor substrate is heated to allow the previously generated acid to expand. Each corner of the resist layer and the second photoresist layer
569305 五、發明說明（3) 層與第二光阻層之界面發 ^ μ m -4 ^ ^ , 龛生架橋連結反應，產生一架橋連 第一光阻層表面。接著如步驟4、5所示， -铋Μ $ $反應第一先阻層移除，產生一 CD縮小之筮 一钱刻遮罩圖案。 弟 如前所述，在 圖案區域與低密度 使得由第一光阻層 分佈不均勻，換句 光阻層内的質子酸 區域的第一光阻層 第一光阻層的玻璃 temperature，Tg) 一來，在後續進行 由於質子酸分佈濃 生CD縮小之均勻度 發明内容 完成第一 接觸洞圖 所構成之 話說，在 分佈濃度 内的質子 轉化溫度 ，導致第 架橋連結 度不同或 不佳的問 步驟後’由於在高密度接觸洞 案區域的曝光特性不同使然， 第一蝕刻遮罩圖案上的質子酸 高密度接觸洞圖案區域的第_ 會稱高於在低密度接觸洞圖案 酸分佈濃度，這同時也影響到 (glass transition 一光阻層的特性不一致。如此 反應時，或者進行熱流法時， 者玻璃轉化溫度不同，即會發 題0 因此’本發明的主要目的在於提供一種可提高CD縮小 之均勻度的方法。 為達上述目的，本發明提供一種縮小半導體元件臨界 尺寸之方法，包含有下列步驟：於一半導體層上形成一光569305 V. Description of the invention (3) The interface between the layer (3) and the second photoresist layer is ^ μm -4 ^ ^, and a bridge connection reaction is generated, resulting in a bridge connecting the surface of the first photoresist layer. Then, as shown in steps 4 and 5, the bismuth M $$ reacts to the removal of the first resistive layer, generating a CD shrinkage mask and a money mask pattern. As mentioned earlier, the low density in the pattern area makes the first photoresist layer unevenly distributed. In other words, the first photoresist layer in the proton acid region in the photoresist layer has a glass temperature (Tg). In the future, the uniformity of the shrinkage of the protonic acid distribution due to the concentration of the compacted CD was completed. According to the completion of the first contact hole map, the proton conversion temperature within the distribution concentration caused different or poor bridge connection problems. After the step, due to the different exposure characteristics in the high-density contact hole area, the first _ of the proton acid high-density contact hole pattern area on the first etching mask pattern will be said to be higher than the acid distribution concentration in the low-density contact hole pattern. This also affects the inconsistent characteristics of the glass transition photoresist layer. In such a reaction, or when the heat flow method is performed, the glass transition temperature is different, which will cause the problem 0. Therefore, the main purpose of the present invention is to provide a method for improving the CD Method for reducing uniformity. In order to achieve the above object, the present invention provides a method for reducing the critical dimension of a semiconductor device, including the following: Steps of: forming a semiconductor layer on a light
第8頁 569305 五、發明說明（4) 阻層’其已至少經過曝光顯影處理，構成一暴露出部份該 半導體層之第一圖案；進行一全面曝光（blanket exposure)步驟，以該光阻層可吸收光波長之光線照射該 光阻層以及暴露出之該半導體層，以提供該光阻層一預定 能量，俾產生光質子酸；進行一第一熱製程，使前一步驟 ^於該光阻層產生之光質子酸進行鍊反應，並且均一化該 =阻層之玻璃轉化溫度（Tg);以及進行一第二熱製程，^ ，第一熱製程係在一低於該玻璃轉化溫度（Tg)之溫度; 技術；委！能更進一步了解本發明之特徵及 而所附圖式僅供參考盥々明田廿北田七月與附圖。然 制者。 亏^ s兄月用，並非用來對本發明加以限 實施方式 用以圖式所舉僅為本發明之一較佳眚#在丨 明申Κ本發明之範嘴者。本發明之範.以：例祕並非 月申凊專利範圍所主張者為^ ^月之乾可貫際應依據本發 圖。首I閱，一，圖二為本發明縮小元件CD方、、、ώ # 自先，如步驟】一 ^ W万法之流程 塗佈於-半導光可產生酸之光阻層被 底上。依據本發明之較佳實施例，光阻Page 8 569305 V. Description of the invention (4) The resist layer has been subjected to at least exposure and development processing to form a first pattern exposing part of the semiconductor layer; a blanket exposure step is performed to use the photoresist The layer can absorb light with a wavelength of light to irradiate the photoresist layer and the exposed semiconductor layer to provide the photoresist layer with a predetermined energy to generate photoprotonic acid; a first thermal process is performed so that the previous step ^ The photoprotic acid produced by the photoresist layer undergoes a chain reaction and uniformizes the glass transition temperature (Tg) of the resist layer; and a second thermal process is performed, the first thermal process is at a temperature lower than the glass transition temperature. (Tg) temperature; technology; commission! The features of the present invention can be further understood, and the drawings are for reference only. Ran producer. However, it is not intended to limit the present invention. The embodiments are only one of the preferred embodiments of the present invention. The scope of the present invention is based on the following: The example is not the one claimed in the scope of the patent application for the month. First, I, Figure 2, Figure 2 shows the reduced component CD of the present invention. [Previously, as a step] a ^ W process method is applied on-the semi-conductive light can generate acid on the photoresist layer on the bottom . According to a preferred embodiment of the present invention, the photoresist
569305 五、發明說明（5) 層為一化學增幅型（chemical amplification)光阻，其包 含有酴酸型環氧樹脂（novolac-based resin)以及芳香族 胺類光感應劑（naphtha-quinone diazide - photosensitive agent)。光阻層另含有光酸產生劑。舉 例來說，光阻層約0 · 2至0 · 8微米厚，且一般需經過7 0°C至 1 0 0°C約1分鐘左右之預烤（p r e - b a k i n g)處理。光線經由一 預定光罩圖案對第一光阻層進行曝光。曝光光源可以為汞 燈（mercury 1 amp)所發出之g - 1 i ne或i - 1 i ne光線，其曝照 時間約對應於2 0 0至1 0 0 0 mj/cm乏單位能量。有時為了增 加解析度’曝光後之光阻層可再經過一道1 〇 〇至1 6 Qt後烤 (post exposure baking)處理。接著進行顯影，利用例如 2 wt°/G之 TMAH(tetra-methyl-ammonium hydroxide)稀釋水 溶液將光阻層經過光線照射過之區域溶解去除，產生一第 一蝕刻遮罩圖案。 如前所述，在完成第一步驟後，由於在高密度接觸洞 圖案區域與低密度接觸洞圖案區域的曝光特性不同使然， 使得由光阻層所構成之第一蝕刻遮罩圖案上的質子酸分佈 不均勻，換句話說，在高密度接觸洞圖案區域的光阻層内 的質子酸分佈濃度會稍高於在低密度接觸洞圖案區域的光 阻層内的質子酸分佈濃度，這同時也影響到光阻層的玻璃 轉化溫度（Tg)，導致光阻層的特性不一致。如光此一曰來的” 後續進行架橋連結反應時，或者進行熱流法（t h e r m a 1 flow)時，由於質子酸分佈濃度不同或者玻璃轉化溫度不569305 V. Description of the invention (5) The layer is a chemical amplification photoresist, which contains novolac-based resin and aromatic amine light-sensing agent (naphtha-quinone diazide- photosensitive agent). The photoresist layer further contains a photoacid generator. For example, the photoresist layer is about 0. 2 to 0. 8 microns thick, and generally needs to be pre-baked (p r e-b a k i n g) for about 1 minute at 70 ° C to 100 ° C. The light is exposed to the first photoresist layer through a predetermined mask pattern. The exposure light source can be g-1 i ne or i-1 i ne light from a mercury 1 amp. The exposure time corresponds to about 2000 to 100 mj / cm of unit energy. Sometimes in order to increase the resolution, the photoresist layer may be subjected to a post exposure baking process from 1000 to 16 Qt. Then, development is performed, and a photoresist layer is dissolved and removed by using a dilute aqueous solution of TMAH (tetra-methyl-ammonium hydroxide) at 2 wt ° / G to generate a first etching mask pattern. As mentioned above, after the first step is completed, the protons on the first etching mask pattern composed of the photoresist layer are caused by the difference in exposure characteristics between the high-density contact hole pattern region and the low-density contact hole pattern region. The acid distribution is not uniform. In other words, the proton acid distribution concentration in the photoresist layer in the high density contact hole pattern area will be slightly higher than the proton acid distribution concentration in the photoresist layer in the low density contact hole pattern area. It also affects the glass transition temperature (Tg) of the photoresist layer, resulting in inconsistent characteristics of the photoresist layer. When the “bridge connection reaction” is followed, or the heat flow method (t h e r m a 1 flow), the proton acid distribution concentration is different or the glass transition temperature is different.
第10頁 569305 五、發明說明（6) 同’即會發生CD縮小之均勻度不佳的問題。本發明之主要 目的即在改善此一不均勻性。 在步驟2 0中’接著將已經曝光顯影之光阻層以及已經 暴露出之半導體基底照射與先前曝光光阻層相同之曝光光 源，.例如曝光光源可以為汞燈（merCUry lamp)所發出之 g - 1 i n e或i - 1 i n e光線。該曝光光源係光阻層可吸收光波長 之光線，以提供該光阻層一預定能量，俾產生光質子酸 (photo generated acid)。全面性曝光的目的在使已經曝 光顯影之光阻層各部份產生質子酸，因此此曝光步驟所用 之能量不宜過高。較佳者，該預定能量約為1〇%〜15〇%]£。， 其中，E為將該光阻完全清除之恕限能量（thresh〇1(1 energy )。依據本發明之較佳實施例，全面性曝光所執行 之時間約相對應於曝光能量2 m J / c m 2。 在步驟3 0中’接著將經過全面性曝光處理之光阻層施 以第一道熱處理，使前一步驟中於光阻層產生之光質子^ 進行鍊反應或擴散反應，並且均一化光阻層之玻璃轉化^ 度（T g)。第一道熱處理建議其製程溫度需小於光阻層之破 璃轉化溫度（Tg)，例如110°C至160°C持需加熱約60秒左 右。在經過步驟2 0以及3 0之處理後，原先存在於光阻層中 質子酸分佈不均的不利因素已經消除，而且可將光阻層的 玻璃轉化溫度（T g)調整至均一狀態。Page 10 569305 V. Description of the invention (6) Same as ’, the problem of poor uniformity of CD shrinkage occurs. The main object of the present invention is to improve this unevenness. In step 20, 'the exposed and developed photoresist layer and the exposed semiconductor substrate are then irradiated with the same exposure light source as the previously exposed photoresist layer. For example, the exposure light source may be g emitted by a mercury lamp (merCUry lamp). -1 ine or i-1 ine light. The exposure light source is a photoresist layer capable of absorbing light at a wavelength of light to provide a predetermined energy for the photoresist layer to generate photo generated acid. The purpose of comprehensive exposure is to generate protonic acid in each part of the photoresist layer that has been developed by exposure. Therefore, the energy used in this exposure step should not be too high. Preferably, the predetermined energy is about 10% to 15%. Among them, E is the threshold energy (three energy (1 energy)) for completely removing the photoresist. According to a preferred embodiment of the present invention, the time for performing the comprehensive exposure corresponds to about 2 m J / cm 2. In step 30, 'the photoresist layer subjected to the comprehensive exposure treatment is then subjected to the first heat treatment, so that the photoprotons generated in the photoresist layer in the previous step ^ undergo a chain reaction or a diffusion reaction, and are uniform The glass transition temperature (T g) of the photoresist layer. The first heat treatment suggests that the process temperature should be lower than the glass transition temperature (Tg) of the photoresist layer, for example, 110 ° C to 160 ° C. It takes about 60 seconds to heat. After the treatment of steps 20 and 30, the disadvantages of the uneven distribution of the protonic acid in the photoresist layer have been eliminated, and the glass transition temperature (T g) of the photoresist layer can be adjusted to a uniform state. .
569305 五、發明說明（7) (erotic 4〇中，含有可與光阻層發生架橋連結 八+ js m J^nklng)反應之高分子層被覆蓋在光阻層上。高 I π二絲a有在酸的存在下可發生架橋連結反應之成分， # i ^ γ丨於，法溶解光阻層之溶劑中。依據本發明之一較 Ϊίί Ϊ :局分子層含有架橋劑（Cr〇SS —link aSent)，而 ί據另一較佳實施例，胃分子層含有水溶性高分 、本毛明之又另一較佳實施例，步驟4 0係可以省 略。 ㈡ 接著如步驟5 0所示，對半導體基底進行第二道执處 理，以使先前所產生的酸得以擴散至光阻層各角落至該高 分子層，俾使在第一光阻層與該高分子層之界面發生架橋 連結反應’產生一架橋連結層覆蓋於光阻層表面。一般而 言，第二道熱處理的製程溫度約略高於光阻層之玻璃轉化 溫度（T g)。 一接著如步驟60及步驟70所示，將未發生架橋連結反應 之咼分子層移除，產生一 C D縮小之第二蝕刻遮罩圖案。去 除未與光阻層發生化學架橋連結反應之·高分子層係利用一 清洗溶液，其中該清洗溶液僅可溶解該高分子層，而無法 ✓谷解該光阻層以及與該光阻層發生化學架橋連結反應者。 最後經由該第一餘刻遮罩圖案作為遮罩，進行乾姓刻以蝕 刻下方之半導體層。 569305569305 V. Description of the invention (7) (erotic 40), a polymer layer containing a reaction capable of bridging with the photoresist layer (8 + js m J ^ nklng) is covered on the photoresist layer. The high I π difilament a has a component that can undergo a bridging connection reaction in the presence of an acid. # I ^ γ 丨 is used to dissolve the photoresist layer in a solvent. According to one aspect of the present invention, the local molecular layer contains a bridging agent (CrOSS-link aSent), and according to another preferred embodiment, the gastric molecular layer contains a high water-soluble component, which is another In the preferred embodiment, step 40 can be omitted. ㈡ Next, as shown in step 50, a second treatment is performed on the semiconductor substrate, so that the previously generated acid can be diffused to each corner of the photoresist layer to the polymer layer, and the first photoresist layer and the A bridging connection reaction occurs at the interface of the polymer layer to generate a bridging connection layer covering the surface of the photoresist layer. In general, the process temperature of the second heat treatment is slightly higher than the glass transition temperature (T g) of the photoresist layer. Next, as shown in steps 60 and 70, the plutonium molecular layer that has not undergone the bridge connection reaction is removed, and a second etching mask pattern with a reduced C D is generated. The polymer layer that removes the chemical bridging reaction that does not occur with the photoresist layer uses a cleaning solution, where the cleaning solution can only dissolve the polymer layer, and cannot be disassembled Chemical bridging links reactors. Finally, the first remaining etching mask pattern is used as a mask, and the dry semiconductor layer is etched to etch the semiconductor layer below. 569305
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569305 圖式簡單說明 圖式之簡單說明 圖一為習知RELACS法之流程圖。 圖二為本發明縮小元件CD方法之流程圖。 圖式之符號說明569305 Simple illustration of the diagram Simple illustration of the diagram Figure 1 is a flowchart of the conventional RELACS method. FIG. 2 is a flowchart of a method for reducing a component CD according to the present invention. Schematic symbol description
第14頁 1 步 驟 1 第 一 光阻 層 曝 光 顯 影 2 步 驟 2 覆 蓋 第二 光 阻 層 3 步 驟 3 熱 處 理 4 步 驟 4 清 洗 5 步 驟 5 完 成 CD縮 小 之 蝕 刻 遮 罩 10 步 驟 1 光 阻 層曝 光 顯 影 20 步 驟 2 全 面 性曝 光 30 步 驟 3 第 道熱 處 理 40 步 驟 4 覆 蓋 高分 子 層 50 步 驟 5 第 二 道熱 處 理 60 步 驟 6 清 洗 70 步 驟 7 完 成 CD縮 小 之 蝕 刻 遮 罩Page 14 1 Step 1 Exposure and development of the first photoresist layer 2 Step 2 Covering the second photoresist layer 3 Step 3 Heat treatment 4 Step 4 Cleaning 5 Step 5 Complete the etching mask for CD reduction 10 Step 1 Exposure and development of the photoresist layer 20 Step 2 Full exposure 30 Step 3 The first heat treatment 40 Step 4 Covering the polymer layer 50 Step 5 The second heat treatment 60 Step 6 Cleaning 70 Step 7 Complete the etching mask for CD reduction