A7 B7 4996twf. doc/008 五、發明説明（（） (請先閲讀背面之注意事項再填寫本頁) 本發明是有關於一種相移式光罩（Phase Shifting Mask; PSM)的製造方法，且特別是有關於一種Levenson 型相移式光罩的製造方法。 由於相移式光罩具有提昇曝光解析度的優點，因此目 前的積體電路製程大多都已.採用相移式光罩來進行微影 製程。具有圖案的相移式光罩上具有透光區與不透光區， 而透光區中又包括相移區與非相移區。經由相移區通過光 罩的光波與經過非相移區通過光罩的光波之間的有一個 相位差。在進行微影製程時，藉著經過相移區與非相移區 之光波之間的正反相干涉來增加曝光時的解析度。而 Levenson型相移式光罩則是藉由調整光罩基板的厚度來 形成相移區與非相移區。 第1A圖至第1C圖繪示習知一種Levenson型相移式光 罩的製程剖面圖。 經濟部智慧財產局員工消費合作社印製 請參照第1A圖，習知形成Levenson型相移式光罩的 方法是先提供一個光罩基板100，並形成不透光層102全 面覆蓋光罩基板100。接著，於不透光層102上形成具有 特定圖案的第一光阻層104。其中，形成第一光阻層104 的方法是先形成一層光阻（未繪示於圖中）全面覆蓋不透光 層1〇2，利用電子束描繪法(E-Beam Writing)來進行曝光步 驟，以定義出第一光阻層104的圖形，再進行顯影步驟。 之後，以第一光阻層104爲罩幕，進行蝕刻步驟，移除暴 露出來的不透光層102，以定義出透光區106與不透光區 108 ° 3 本紙張尺度適用中國國家標隼（CNS ) A4規格（210X297公釐） — 4996twf.doc/008 B7 五、發明説明（i) 請參照第1B圖，移除第一光阻層1〇1 2(繪示於第1A圖 中）之後，形成第二光阻層110全面覆蓋光罩基板1〇〇。接 著，進行另一次的電子束描繪與顯影步驟，以定義出第二 光阻層11 〇的圖形。接著’以第二光阻層11 〇爲罩幕，進 行飽刻步驟，於光罩基底中形成溝渠112，同時定義 出相移區114。 請參照第1C圖，移除第一光阻層11 〇(繪示於第iB圖 中）’以完成Levenson型相移式光罩。其中，具有不透光 層1〇2的區域爲不透光區108 ’而透光區ι〇6則是由具有 溝渠112之區域的相移區114與光罩基板10〇維持原來厚 度的非相移區116所組成。 經濟部智慧財產局員工消費合作社印製 ---------!';袭丨| (請先閲讀背面之注意事項再填寫本頁) 上述的方法需進行兩次電子束描繪以及兩次蝕刻步 驟，由於要將兩次電子束描繪的步驟互相配合並不容易， 因此常會發生所定義之圖案的位置不對或甚至於圖案錯 誤的問題。此外，由於光波通過光罩之後的相位(Phase)與 其所經過之光罩基板的厚度有關，因此溝渠的深度需精確 的控制，以使通過相移區與非相移區的光波具有180度的 相位差。而進行兩次蝕刻步驟會因爲蝕刻之位置與深度的 誤差而對於光罩圖案與溝渠深度的掌握產生不利的影 響。 因此，本發明提供一種Levenson型相移式光罩的製造 方法，此方法只需要進行一次電子束描繪與一次蝕刻步 驟，就可以在光罩基板上定義出不透光區、相移區與非相 移區，以避免圖案錯誤或所形成之溝渠深度不精確的問 1 2 本氏張尺度適用中國國家標準（CNS ) A1聽·（ 210X297公釐） 4"6tvvf.doc/008 A7 -^_B7__ 五、發明説明（> ) 題。 本發明提供一種Levenson型相移式光罩的製造方法， 此方法是提供一個覆蓋有不透光層的光罩基板，並形成矽 化光阻層全面覆蓋不透光層。其中，所提供之光罩基板具 有均勻的厚度，且其材質爲可透光。接著，利用電子束描 繪法來進行曝光，再進行顯影步驟，以定義出矽化光阻層 的圖形。其中’被所形成之矽化光阻層所覆蓋的區域定義 爲保護區，而暴露出不透光層的區域則定義爲相移區。接 著，進行矽化反應（Silylation)，使部分的矽化光阻層變質 爲矽化層。其中，所形成之矽化層與未變質的矽化光阻層 共形（Conformal)。移除砂化光阻層上方之矽化層，僅留下 緊接於未變質之矽化光阻層兩側的矽化層，也就是使未變 質的矽化光阻層暴露出來。之後，進行飩刻步驟，以移除 保護區中的砍化光阻層、位於相移區中與原本被砂化光阻 層所覆蓋的不透光層，以及位於相移區中的部分光罩基 底’以於相移區之光罩基底中形成溝渠。接著，移除矽化 層。 在以上述之方法所形成的結構中，不透光層未被移除 的區域中因其無法透光，故稱爲不透光區。而沒有不透光 層覆蓋的區域則爲透光區。透光區包括了具有溝渠的相移 區與維持原厚度之光罩基板的非相移區。 本發明的一個特徵爲只進行一次的電子束描繪曝光步 驟以及一次的蝕刻步驟，就可以在光罩基板上定義出不透 光區、相移區與非相移區。由於減少了電子束描繪曝光步 5 本紙張尺度適用中國國家標準（CNS ) A4規格（21〇'乂297公釐） (請先閲讀背面之注意事項再填寫本頁) ，裝. 訂 經濟部智慧財產局員工消費合作社印製 4996twf.doc/008 tlA7 B7 4996twf. Doc / 008 5. Description of the invention (() (Please read the notes on the back before filling this page) The present invention relates to a method for manufacturing a phase shift mask (PSM), and In particular, it relates to a method for manufacturing a Levenson type phase shift mask. Because the phase shift mask has the advantage of improving the exposure resolution, most of the current integrated circuit manufacturing processes have been adopted. The phase shift mask is used for micro Photographic process. The phase-shifting mask with a pattern has transparent and opaque areas, and the light-transmitting area includes phase-shifting and non-phase-shifting areas. The light waves passing through the mask through the phase-shifting area and passing through the There is a phase difference between the light waves passing through the mask in the phase shift area. During the lithography process, the resolution during exposure is increased by the positive and negative interference between the light waves passing through the phase shift area and the non-phase shift area. The Levenson phase-shifting photomask is formed by adjusting the thickness of the mask substrate to form a phase-shifted region and a non-phase-shifted region. Figures 1A to 1C show a conventional Levenson-type phase-shifting photomask. Manufacturing process profile. Please refer to FIG. 1A for printing by Fei Cooperative. The conventional method for forming a Levenson-type phase-shifting photomask is to first provide a photomask substrate 100 and form an opaque layer 102 to cover the photomask substrate 100 in its entirety. A first photoresist layer 104 having a specific pattern is formed on the light layer 102. The method for forming the first photoresist layer 104 is to first form a photoresist (not shown in the figure) to cover the opaque layer 100 , Using the E-Beam Writing method to perform the exposure step to define the pattern of the first photoresist layer 104, and then the development step. After that, the first photoresist layer 104 is used as a mask to perform the etching step. , Remove the exposed opaque layer 102 to define the transparent area 106 and the opaque area 108 ° 3 This paper size applies to China National Standard (CNS) A4 specification (210X297 mm) — 4996twf.doc / 008 B7 V. Description of the invention (i) Please refer to FIG. 1B. After removing the first photoresist layer 1012 (shown in FIG. 1A), a second photoresist layer 110 is formed to completely cover the photomask substrate 1. 〇〇. Then, another electron beam drawing and developing step is performed to define The pattern of the second photoresist layer 11 〇. Then, using the second photoresist layer 11 〇 as a mask, perform a saturation step to form a trench 112 in the photomask base and define a phase shift region 114. Please refer to 1C In the figure, the first photoresist layer 11 〇 (shown in the figure iB) is removed to complete a Levenson-type phase shift photomask. Among them, the area having the opaque layer 102 is the opaque area 108 ′ The light-transmitting region ιo6 is composed of a phase-shifting region 114 having a trench 112 and a non-phase-shifting region 116 which maintains the original thickness of the mask substrate 100. Printed by the Consumer Cooperative of the Intellectual Property Bureau of the Ministry of Economic Affairs ---------! '; Strike 丨 | (Please read the precautions on the back before filling this page) The above method requires two electron beam depictions and two In the secondary etching step, since it is not easy to coordinate the two electron beam drawing steps with each other, the problem that the position of the defined pattern is incorrect or even the wrong pattern often occurs. In addition, since the phase after the light wave passes through the mask is related to the thickness of the mask substrate it passes through, the depth of the trench needs to be precisely controlled so that the light waves passing through the phase-shifted region and the non-phase-shifted region have a 180 degree Phase difference. However, performing two etching steps will have an adverse effect on the mastering of the mask pattern and trench depth due to the difference in the position and depth of the etching. Therefore, the present invention provides a method for manufacturing a Levenson-type phase shift mask. This method only needs to perform one electron beam drawing and one etching step to define an opaque region, a phase shift region, and a non-transparent region on the mask substrate. Phase shift area to avoid pattern errors or inaccurate trench depth. 1 2 This scale is applicable to China National Standard (CNS) A1. (210X297 mm) 4 " 6tvvf.doc / 008 A7-^ _ B7__ V. Description of the Invention (>) The invention provides a method for manufacturing a Levenson-type phase shift photomask. This method is to provide a photomask substrate covered with an opaque layer, and form a silicided photoresist layer to cover the opaque layer completely. Among them, the provided photomask substrate has a uniform thickness, and its material is transparent. Next, exposure is performed using an electron beam tracing method, and then a developing step is performed to define a pattern of the silicided photoresist layer. Among them, the area covered by the formed silicided photoresist layer is defined as the protection area, and the area where the opaque layer is exposed is defined as the phase shift area. Then, a silicidation reaction is performed to partially modify the silicidated photoresist layer to a silicidated layer. Among them, the formed silicide layer and the unmodified silicide photoresist layer are conformal. The silicide layer on the sanded photoresist layer is removed, leaving only the silicide layers on both sides of the undegraded silicide photoresist layer, that is, the undegraded silicide photoresist layer is exposed. Then, an engraving step is performed to remove the cleaved photoresist layer in the protection area, the opaque layer located in the phase shift area and originally covered by the sanded photoresist layer, and part of the light in the phase shift area. The mask substrate 'forms a trench in the mask substrate of the phase shift region. Then, the silicide layer is removed. In the structure formed by the above method, the area where the opaque layer has not been removed is called an opaque area because it cannot transmit light. The area not covered by the opaque layer is the light-transmissive area. The light-transmitting area includes a phase-shifted area with trenches and a non-phase-shifted area of the mask substrate maintaining the original thickness. A feature of the present invention is that only one electron beam drawing exposure step and one etching step can be performed to define an opaque region, a phase shift region, and a non-phase shift region on the mask substrate. Due to reduced exposure steps for electron beam drawing 5 This paper size applies Chinese National Standard (CNS) A4 specification (21〇 '乂 297 mm) (Please read the precautions on the back before filling this page) Printed by the Property Agency Staff Consumer Cooperatives 4996twf.doc / 008 tl
dI 五、發明説明（b ) 驟與蝕刻步驟的次數，因此可以有效的減少圖案誤對準 (Misalign)與蝕刻錯誤的問題。 爲讓本發明之上述和其他目的、特徵、和優點能更明 顯易懂，下文特舉一較佳實施例，並配合所附圖式，作詳 細說明如下： 圖式之簡單說明： 第1A圖至第1C圖繪示習知一種Levenson型相移式光 罩的製程剖面圖；以及 第2 A圖至第2E圖繪示依照本發明之一較佳實施例， 一種Levenson型相移式光罩的製程剖面圖。 圖示之標號說明： 100、200 :光罩基板 102、202、202a :不透光層 104 :第一光阻層 106 :透光區 108 :不透光區 110 :第二光阻層 112、212 :溝渠 114、206:相移區 116、214 :非相移區 204、204a :矽化光阻層 208 :保護區 210、210a :矽化層 實施例 請參照第2A圖，首先，提供一個厚度均勻的光罩基板 6 本紙用中國國家標準（CNS ) A4規格（2!0X297公釐） (請先閱讀背面之注意事項再填寫本頁) '策· 訂 經濟部智慧財產局員工消費合作社印製 A7 A7 4996twf.doc/008 B7________ 五、發明説明（έ ) (請先閱讀背面之注意事項再填寫本頁) 200，並形成不透光層202全面覆蓋光罩基板200。其中， 光罩基板200係採用可透光的材質，比如爲石英或是玻 璃，而不透光層202則需具有阻擋光線的功能，其材質比 如爲鉻。接著，形成矽化光阻層204全面覆蓋不透光層 202，再以電子束描繪法進行曝光步驟。之後，進行顯影 步驟，以定義出矽化光阻層204的圖形。其中，未被矽化 光阻層204覆蓋的區域定義爲相移區206，而被砍化光阻 層204覆蓋的區域則爲保護區208。 請參照第2B圖，進行矽化反應，以使部分的矽化光阻 層204(繪示於第2A圖中）變質爲矽化層210。其中，所形 成之矽化層210與未變質的矽化光阻層204a共形。進行矽 化反應的方法比如爲在具有矽的環境下加熱，以使矽化光 阻變質爲矽化物。由於反應將由矽化光阻層204暴露出來 的上方與側壁開始進行，因此可以藉著控制此矽化反應的 時間來掌握所形成之矽化層210的厚度。 請參照第2C圖，移除矽化光阻層204a上方的矽化層 21〇(繪示於第2B圖中），留下緊接於矽化光阻層204a之側 壁的砂化層210a，而使未變質的砍化光阻層204a暴露出 來。進行此步驟的方法比如爲回蝕刻法(Etch Back)。 經濟部智慧財產局員工消費合作社印製 請參照第2D圖，以矽化層210a爲罩幕，進行蝕刻步 驟，以移除矽化光阻層204a、位於相移區206中之不透光 層2〇2(繪示於第2C圖中）、不透光層202原本被矽化光阻 層204a覆蓋的部分，以及位於相移區206中的部分光罩基 板200，以於相移區206中形成溝渠212並暴露出保護區 208中的部分光罩基板200。而矽化層2l〇a與位於矽化層 7 本紙張尺度適用中國國家標準（CNS ) A4規格（210X297公釐） A7 4996twf.doc/008 ^ 五、發明説明（（） 210a下方的不透光層202a則被保留下來。其中，保護區 208中暴露出光罩基板200的區域則定義爲非相移區 214。在進行此鈾刻步驟時，需精確的控制溝渠212的深 度，以使光罩基板200在相移區206的厚度小於其在非相 移區214的厚度，並且使相移區206與非相移區214之間 具有180度的相移角。也就是說，原本同相位的光波在分 別經由相移區206與非相移區214通過光罩基板200之 後，將會產生180度的相位差。 請參照第2E圖，移除矽化層210(繪示於第2D圖中）， 以完成Levenson型相移式光罩。 綜上所述，本發明的特徵之一爲進行一次電子束描繪 曝光來定義矽化光阻層的圖案，並藉由矽化反應形成矽化 層，以作爲蝕刻步驟的罩幕。在本發明所提供的方法中只 需進行一次電子束描繪曝光步驟，因此可以避免多次電子 束曝光步驟所可能造成之圖案誤對準的情形。此外，本發 明的方法也只需進行一次蝕刻步驟，因此避免了因爲多次 蝕刻步驟定義光罩圖案導致之蝕刻位置錯誤與蝕刻深度 不易控制的問題。 雖然本發明已以一較佳實施例揭露如上，然其並非用 以限定本發明，任何熟習此技藝者，在不脫離本發明之精 神和範圍內，當可作各種之更動與潤飾，因此本發明之保 護範圍當視後附之申請專利範圍所界定者爲準。 8 本紙張尺度適用^國國家標準（CNS )^4規格（210X297公釐） ---------装 II (請先閲讀背面之注意事項再填寫本頁) --訂 經濟部智慧財產局員工消費合作社印製dI 5. Description of the invention (b) The number of steps and etching steps can effectively reduce the problem of misalignment and etching errors. In order to make the above and other objects, features, and advantages of the present invention more comprehensible, a preferred embodiment is described below in detail with the accompanying drawings as follows: Brief description of the drawings: FIG. 1A FIG. 1 to FIG. 1C are process cross-sectional views of a conventional Levenson type phase shift photomask; and FIGS. 2A to 2E show a Levenson type phase shift photomask according to a preferred embodiment of the present invention. Process cross-section. Description of the symbols in the figure: 100, 200: photomask substrates 102, 202, 202a: opaque layer 104: first photoresist layer 106: transparent area 108: opaque area 110: second photoresist layer 112, 212: trenches 114, 206: phase-shifted regions 116, 214: non-phase-shifted regions 204, 204a: silicidated photoresist layer 208: protection regions 210, 210a: silicidated layer. Please refer to Figure 2A for an example. First, provide a uniform thickness Photomask substrate 6 This paper uses the Chinese National Standard (CNS) A4 specification (2! 0X297 mm) (Please read the precautions on the back before filling out this page) 'Order · Order A7 printed by the Intellectual Property Bureau of the Ministry of Economic Affairs and Consumer Cooperatives A7 4996twf.doc / 008 B7________ 5. Description of the Invention (Hand) (Please read the precautions on the back before filling out this page) 200, and form an opaque layer 202 to completely cover the mask substrate 200. The mask substrate 200 is made of a light-transmissive material, such as quartz or glass, and the opaque layer 202 needs to have a function of blocking light, and the material is, for example, chromium. Next, a silicided photoresist layer 204 is formed to cover the opaque layer 202 in its entirety, and then an exposure step is performed by an electron beam drawing method. Thereafter, a developing step is performed to define a pattern of the silicided photoresist layer 204. The area not covered by the silicided photoresist layer 204 is defined as the phase shift region 206, and the area covered by the cleaved photoresist layer 204 is the protection region 208. Referring to FIG. 2B, a silicidation reaction is performed, so that a part of the silicidated photoresist layer 204 (shown in FIG. 2A) is modified into a silicidated layer 210. Among them, the formed silicide layer 210 is conformal with the unmodified silicide photoresist layer 204a. The method for performing the silicidation reaction is, for example, heating in an environment with silicon to change the silicidated photoresist to a silicide. Since the reaction starts from the upper and sidewalls exposed by the silicided photoresist layer 204, the thickness of the silicided layer 210 can be grasped by controlling the time of the silicidation reaction. Referring to FIG. 2C, the silicide layer 21 (above shown in FIG. 2B) is removed above the silicide photoresist layer 204a, leaving a sanded layer 210a next to the sidewall of the silicide photoresist layer 204a, so that The deteriorated cleaved photoresist layer 204a is exposed. A method for performing this step is, for example, an Etch Back method. Printed by the Consumer Cooperative of the Intellectual Property Bureau of the Ministry of Economic Affairs, please refer to Figure 2D. With the silicide layer 210a as a mask, an etching step is performed to remove the silicide photoresist layer 204a and the opaque layer 2 in the phase shift region 206. 2 (shown in FIG. 2C), a portion of the opaque layer 202 that was originally covered by the silicided photoresist layer 204a, and a portion of the mask substrate 200 in the phase shift region 206, so as to form a trench in the phase shift region 206 212 and a part of the mask substrate 200 in the protection area 208 is exposed. The siliconized layer 21a and the siliconized layer 7 are located in this paper. The paper size is applicable to the Chinese National Standard (CNS) A4 specification (210X297 mm) A7 4996twf.doc / 008 ^ V. Description of the invention (() The opaque layer 202a under 210a It is preserved. Among them, the area in the protection area 208 where the photomask substrate 200 is exposed is defined as the non-phase-shifted area 214. During this uranium engraving step, the depth of the trench 212 needs to be accurately controlled to make the photomask substrate 200 The thickness in the phase-shifted region 206 is smaller than the thickness in the non-phase-shifted region 214, and a phase shift angle of 180 degrees is provided between the phase-shifted region 206 and the non-phase-shifted region 214. That is, light waves that are originally in the same phase are in After passing through the mask substrate 200 through the phase shift region 206 and the non-phase shift region 214 respectively, a phase difference of 180 degrees will be generated. Please refer to FIG. 2E and remove the silicide layer 210 (shown in FIG. 2D) to The Levenson phase-shifting photomask is completed. In summary, one of the features of the present invention is to perform an electron beam trace exposure to define the pattern of the silicided photoresist layer, and to form a silicided layer through a silicidation reaction as an etching step. Mask. In the method provided by the present invention Only one electron beam drawing exposure step is required in the process, so that the pattern misalignment caused by multiple electron beam exposure steps can be avoided. In addition, the method of the present invention also only needs to perform one etching step, thus avoiding The sub-etching step defines the problems of erroneous etching position and difficult to control the etching depth caused by the mask pattern. Although the present invention has been disclosed as above with a preferred embodiment, it is not intended to limit the present invention. Without departing from the spirit and scope of the present invention, various modifications and retouching can be made, so the scope of protection of the present invention shall be determined by the scope of the attached patent application. 8 This paper standard applies to the national standard (CNS) ^ 4 Specifications (210X297 mm) --------- Pack II (Please read the precautions on the back before filling this page)-Ordered by the Consumer Cooperative of the Intellectual Property Bureau of the Ministry of Economic Affairs