經濟部智慧財產局員工消費合作社印製 α 63232 Α7 _5228twf.doc/008_ Β7_ 五、發明說明（丨） 本發明是有關於一種使用相移式光罩（Phase Shifting Mask，PSM)的方法，且特別是有關於一種利用單一相移式 光罩，形成兩種不同圖案之方法。 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不透光區，而 透光區又包括相移區與非相移區。經#區通過光罩的 光波，與經過非相移區通過光罩的挺之間有一個相位 差，在進行微影製程時，藉著經過相@_與非相移區之光 波之間的正反相干涉，相移式光罩即_高曝光時的解析 度，習知常用的相移式光罩包括Levenson型相移式光罩 或稱爲交替型相移式光罩(Alternating PSM)。Printed by the Consumer Cooperatives of the Intellectual Property Bureau of the Ministry of Economic Affairs α 63232 Α7 _5228twf.doc / 008_ Β7_ V. Description of the Invention (丨) The present invention relates to a method of using a Phase Shifting Mask (PSM), and particularly It is about a method of forming two different patterns by using a single phase shift mask. Because phase-shift photomasks have the advantage of improving exposure resolution, most current integrated circuit manufacturing processes have already adopted phase-shift photomasks for lithographic processes. The patterned phase-shifting photomask has a opaque region, and the transparent region includes a phase-shift region and a non-phase-shift region. There is a phase difference between the light wave passing through the mask through the # area and the stiffener passing through the mask through the non-phase-shifted area. During the lithography process, the light wave passing through the phase @_ and the non-phase-shifted area Positive and anti-phase interference, phase-shifting photomask is the resolution at high exposure. Commonly used phase-shifting photomasks include Levenson-type phase-shifting photomasks or alternate phase-shifting photomasks (Alternating PSM) .
Levenson型相移式光罩是藉由調整光罩基板的厚度來 形成相移區與非相移區。製作levenson型相移式光罩需要 進行兩次電子束描繪以及兩次蝕刻步驟，第一道電子束描 繪以及第一次蝕刻步驟係用以定義出透光區與不透光區， 而第二道電子束描繪以及第二道蝕刻步驟則用以在光罩基 底中形成溝渠，以定義出相移區。此外，由於光波通過光 罩之後的相位與其所經過的光罩基板的厚度有關，因此控 制蝕刻溝渠的深度，即可使通過相移區與非相移區的光波 可以產生180度的相位差。 其結構係在鉻膜上形成一層相移層，其材料一般爲鉬 矽化合物（MoSixOyNz)或氮氧矽化合物（SiOKNy) ’在微影製 程中，曝光的部份係由相移層與未被鉻膜覆蓋的石英基底 3 -----------^ ^--------訂---I-----線{ _ {請先閱讀背面之注意事項再填寫本頁) 本紙張尺度適用中國國家標準（CNS)A4規格（210 X 297公釐） A7 B7 48^-c12 j_228twf，df^/Af)p 五、發明說明（>) 所構成，相移層在曝光時會造成180度的相位差，由於相 移層是交替的佈置，可造成光源0度與180度相位差交替 分布’其中光繞設的部分可以互相抵銷，而產生光強度爲 〇的點，因而增加微影的解析度。 在現在商業化的半導體微影製程中，所要求的元件尺 寸曰益縮小，光罩的製作也變得更爲複雜與困難，因此製 作光罩所耗費成本也隨之增加。 有鑑於此，本發明提供一種利用同一光罩形成兩種不 同圖案之方法。提供一個交替式相移式光罩，其上圖案包 括位元線接觸窗(Bit-Line Contact, BC)與終端接觸窗(Node Contact, NC)，在不同的離焦狀態進行曝光，轉移到光阻 層上的圖案會有所不同’在製作位元線接觸窗與終端接觸 窗時，在第一種離焦狀態下，相移式光罩上的位元線接觸 窗與終端接觸窗圖案會同時轉移到光阻層上；而在製作位 元線時，調整到第二種離焦狀態下，則相移式光罩只有位 元線接觸窗的圖案會轉移到光阻層上，終端接觸窗的圖案 則不會出現。 由於本案僅利用一個相移式光罩，使用於兩道微影製 程中，較習知的半導體製程節省一個罩幕的使用與設計， 因此可以節省罩幕的使用及製作成本。 爲讓本發明之上述目的、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： 4 本紙張尺度適用中國國家標準（CNS)A4規格（210 X 297公釐） --I---------t--------訂---------線 f . (請先閱讀背面之注意事項再填寫本頁) 經濟部智慧財產局員工消費合作社印製· a b3 232 __ 5228twf.doc/008 A7 R7 經濟部智慧財產局員工消費合作社印製 五、發明說明（？） 第1圖繪示依照本發明一較佳實施例，一種交替型相 移式光罩的佈局設計簡示圖； 第2A圖繪示依照本發明一較佳實施例，利用第1圖 之交替型相移式光罩，在離焦狀態爲-0.2下進行曝光後的 圖形； 第2B圖繪示依照本發明一較佳實施例，利用第1圖 之交替型相移式光罩，在離焦狀態爲+0.4下進行曝光後的 圖形； 第3A圖繪示依照本發明一較佳實施例，利用相移式 光罩進行第一道微影製程的結構剖面圖；以及 第3B圖繪示依照本發明一較佳實施例，利用相移式 光罩進行第二道微影製程的結構剖面圖。 圖示標記說明 10 交替型相移式光罩 12,308b,316a 位元線接觸窗開口圖案 14,308a 終端接觸窗開口圖案 300 半導體基底 302 字元線或閘極 304 間隙壁 306 第一介電層 308 第一光阻層 310 位元線接觸 312 終端接觸 314 第二介電層 5 本紙張尺度適用中國國家標準（CNS)A4規格（210 * 297公釐） (請先閱讀背面之注意事項再填寫本頁) 裝----------訂---------線f 經濟部智慧財產局員工消費合作社印製 d63232 A7 5228twf.doc/008 B7 五、發明說明（b) 316 第二光阻層 實施例 第1圖繪示依照本發明一較佳實施例，一種交替型相 移式光罩的佈局設計簡示圖。在提供的交替型相移式光罩 10中，分別有位元線接觸窗開口圖案12與終端接觸窗開 口圖案Η，其相位彼此互補，比如位元線接觸窗開口圖案 12經曝光後會產生0度的相位差，終端接觸窗開口圖案14 經曝光後則會產生180度的相位差，而位元線接觸窗開口 圖案12的尺寸大於終端接觸窗開口圖案14的尺寸，利用 此一光罩對一晶片進行曝光，可得如第2圖所顯示之圖案。 第2Α圖與第2Β圖分別顯示出曝光時，依據對焦狀態 不同而形成的圖案。 第2Α圖所示，爲離焦狀態爲-0.2微米（.mu.m)時所形 成的圖案，可以看出〇度的位元線接觸窗開口圖案與180 度的終端接觸窗開口圖案均有出現。第2B圖所示爲離焦 狀態爲+0.4微米（.mu.m)時所形成的圖案，由圖片中可以 明顯看到相位差〇度的位元線接觸窗開口圖案I2，但是相 位差180度的終端接觸窗開口圖案14並不會出現；這是 因爲位元線接觸窗開口圖案12在曝光時容許聚焦誤差的 裕度(window)較終端接觸窗開口圖案I4容許聚焦誤差的 裕度大，因此當曝光條件處在離焦狀態下，位元線接觸窗 開口圖案12會比終端接觸窗開口圖案14容易顯影在曝光 後的光阻層上，也就是說在曝光條件處在較大的離焦狀態 下，終端接觸窗開口圖案14將不會出現。 6 ------^------^t--------訂---------線 ί (請先閱讀背面之注意事項再填寫本頁) 本紙張尺度適用中囤國家標準（CNS)A4規格（2KU 297公釐） A7 B7 63 232 5228t\vf,doc/008 五、發明說明（L) 第3A圖與第3B圖所繪示爲利用上述之光罩進行製程 的結構剖面圖。 首先，請參照第3A圖，提供一半導體基底300，在此 半導體基底300上形成有字元線(或閘極結構)302，在字元 線(或閘極結構)302側壁形成有間隙壁304。在此半導體基 底300上形成一層第一介電層306，以覆蓋字元線(或閘極 結構）302、間隙壁304以及其他暴露出來的半導體基底 300，此第一介電層306不僅覆蓋上述結構，還提供平坦 表面，以利後續微影製程的進行。 在第一介電層306上形成一層第一光阻層308，進行 第一道微影製程’在完全聚焦或輕微離焦的狀態下（比如 離焦狀態爲-0.2微米），將一光罩，比如上述之第1圖所繪 示的交替型相移式光罩之圖案轉移當第一光阻層308上， 使第一光阻層308同時具有位元線接觸窗開口圖案308a 與終端接觸窗開口圖案308b。 ， 透過第一光阻層3〇8上的圖案，對第一介電層3(1έ::進 行蝕刻，以在第一介電層306中形成位元線與終端接 開口 ’並在開口中塡入導電材料，以形成位元線接觸 與終端接觸312。在第一介電層306上覆蓋一層第二 層314，第二介電層314上則覆蓋有一層第二光阻層316， 其中第二介電層3!4與第一介電層相同，同樣具有平坦的 表面。 以第1圖所述之交替型相移式光罩進行第二道微影製 程’在較大的離焦狀態（比如離焦狀態爲+0.4微米)下使位 7 本紙張尺度適用中國國家標準（CNS)A4規格（210 X 297公釐） -----------^--------訂---------線(I (請先閱讀背面之注^^項再填寫本頁) 經濟部智慧財產局員工消費合作社印製 4 632 5228twf.doc/008 A7 B7 i、發明說明（&) 元線接觸窗開口圖案316a轉移到第二光阻層316上，注 意在第二光阻層316上並沒有出現終端接觸窗開口的圖 案。 因此，本發明提供一種交替型相移式光罩的使用方法， 在不同的曝光條件下可以在晶片上形成不同的圖案，故可 以使用在不同的微影製程上，以節省光罩的使用數量。由 於設計光罩圖案的製程複雜，且需要耗費較多成本，因此 節省一個光罩的使用即可大幅節省整個半導體製程的成 本。 此外，本發明將位元線接觸窗與終端接觸窗之圖案設 計合倂在同一光罩上，在第一道光阻層上可以同時曝出位 元線接觸窗圖案與終端接觸窗圖案，而無須擔心形成位元 線接觸窗圖案與終端接觸窗圖案時，會有對準誤差的問題 發生。 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。 -----I I [ I--^^--------訂---------線{ (請先閱讀背面之注意事項再填寫本頁) 經濟部智慧財產局員工消費合作社印製 8 本紙張尺度適用中國國家標準（CNS)A4規格（210x297公釐）Levenson-type phase-shifting photomasks form phase-shifted regions and non-phase-shifted regions by adjusting the thickness of the mask substrate. Making the levenson type phase shift mask requires two electron beam drawing and two etching steps. The first electron beam drawing and the first etching step are used to define the transparent and opaque areas, and the second An electron beam trace and a second etching step are used to form a trench in the mask substrate to define a phase shift region. In addition, since the phase of the light wave after passing through the mask is related to the thickness of the mask substrate that it passes through, controlling the depth of the etch trench can make the light wave passing through the phase-shifted region and the non-phase-shifted region produce a 180 degree phase difference. Its structure is to form a phase shift layer on the chromium film. Its material is generally molybdenum silicon compound (MoSixOyNz) or silicon oxynitride compound (SiOKNy). In the lithography process, the exposed part is composed of the phase shift layer and the Quartz substrate covered with chrome film 3 ----------- ^ ^ -------- Order --- I ----- line {_ {Please read the precautions on the back first (Fill in this page) This paper size is in accordance with Chinese National Standard (CNS) A4 (210 X 297 mm) A7 B7 48 ^ -c12 j_228twf, df ^ / Af) p 5. Composition of the invention (>), phase shift The layer will cause a 180-degree phase difference during exposure. Because the phase-shift layers are arranged alternately, the light source can be alternately distributed with 0-degree and 180-degree phase differences. 'The light-wound portions can offset each other, and the light intensity is 〇 points, thus increasing the resolution of lithography. In the current commercial semiconductor lithography process, the required component size has been reduced, and the production of photomasks has become more complicated and difficult. Therefore, the cost of making photomasks has also increased. In view of this, the present invention provides a method for forming two different patterns using the same mask. Provide an alternating phase-shifting photomask with patterns including Bit-Line Contact (BC) and Node Contact (NC), which are exposed in different defocus states and transferred to light The pattern on the resist layer will be different. 'When making the bit line contact window and the terminal contact window, in the first defocused state, the bit line contact window and the terminal contact window pattern on the phase shift mask will be different. At the same time, the photoresist layer is transferred to the photoresist layer. When the bit line is made and adjusted to the second defocus state, only the pattern of the bit line contact window of the phase shift photomask will be transferred to the photoresist layer and the terminal contacts. The window pattern does not appear. Since this case only uses a phase-shifting photomask and is used in two lithography processes, it saves the use and design of a mask compared with the conventional semiconductor process, so it can save the use and production cost of the mask. In order to make the above-mentioned objects, features, and advantages of the present invention more comprehensible, a preferred embodiment is given below in conjunction with the accompanying drawings to make a detailed description as follows: Brief description of the drawings: 4 This paper scale is applicable China National Standard (CNS) A4 Specification (210 X 297 mm) --I --------- t -------- Order --------- line f. ( Please read the notes on the back before filling out this page) Printed by the Consumer Cooperatives of the Intellectual Property Bureau of the Ministry of Economic Affairs · a b3 232 __ 5228twf.doc / 008 A7 R7 Printed by the Consumer Cooperatives of the Intellectual Property Bureau of the Ministry of Economic Affairs Figure 1 shows a schematic layout design of an alternating phase shift mask according to a preferred embodiment of the present invention; Figure 2A shows the alternate use of Figure 1 according to a preferred embodiment of the present invention Figure 2B shows the pattern after exposure at a defocused state of -0.2; Figure 2B shows a preferred embodiment of the present invention, using the alternating phase shift mask of Figure 1, Figure after exposure at +0.4; Figure 3A shows a phase shift mask according to a preferred embodiment of the present invention. A first cross-sectional structure of FIG photolithographic process; and FIG. 3B illustrates a second preferred embodiment according to the present invention, the use of phase-shifted reticle structural cross-sectional view of a second photolithographic manufacturing process. Description of pictographs 10 Alternating phase shift masks 12,308b, 316a Bit line contact window opening pattern 14,308a Terminal contact window opening pattern 300 Semiconductor substrate 302 Word line or gate 304 Spacer 306 First dielectric layer 308 The first photoresist layer 310 bit line contact 312 terminal contact 314 second dielectric layer 5 This paper size applies to China National Standard (CNS) A4 specification (210 * 297 mm) (Please read the precautions on the back before filling in this Page) ---------- Order --------- line f Printed by the Consumer Cooperatives of the Intellectual Property Bureau of the Ministry of Economic Affairs d63232 A7 5228twf.doc / 008 B7 V. Description of Invention (b) 316 Embodiment 2 of the second photoresist layer FIG. 1 is a schematic diagram showing a layout design of an alternating phase shift photomask according to a preferred embodiment of the present invention. In the provided alternate phase-shifting photomask 10, the bit line contact window opening pattern 12 and the terminal contact window opening pattern 分别 are respectively complementary in phase to each other. For example, the bit line contact window opening pattern 12 will be generated after exposure. With a phase difference of 0 degrees, the terminal contact window opening pattern 14 will produce a 180 degree phase difference after exposure, and the size of the bit line contact window opening pattern 12 is larger than that of the terminal contact window opening pattern 14. Using this photomask By exposing a wafer, a pattern as shown in FIG. 2 can be obtained. Figures 2A and 2B show the patterns formed depending on the focus state during exposure. Figure 2A shows the pattern formed when the defocus state is -0.2 microns (.mu.m). It can be seen that the opening pattern of the bit line contact window at 0 degrees and the opening pattern of the terminal contact window at 180 degrees are both appear. Figure 2B shows the pattern formed when the defocused state is +0.4 microns (.mu.m). The bit line contact window opening pattern I2 with a phase difference of 0 degrees can be clearly seen in the picture, but the phase difference is 180 Degree terminal contact window opening pattern 14 does not appear; this is because the bit line contact window opening pattern 12 allows a margin of focus error (window) during exposure to be larger than that of the terminal contact window opening pattern I4. Therefore, when the exposure condition is in a defocused state, the bit line contact window opening pattern 12 is easier to develop on the exposed photoresist layer than the terminal contact window opening pattern 14, that is, the exposure condition is larger in the exposure condition. In the defocused state, the terminal contact window opening pattern 14 will not appear. 6 ------ ^ ------ ^ t -------- Order --------- line ί (Please read the notes on the back before filling this page) This Paper size applies to the national standard (CNS) A4 specification (2KU 297 mm) A7 B7 63 232 5228t \ vf, doc / 008 V. Description of the invention (L) Figures 3A and 3B are drawn to use the above A structural cross-sectional view of the photomask for the manufacturing process. First, referring to FIG. 3A, a semiconductor substrate 300 is provided. A word line (or gate structure) 302 is formed on the semiconductor substrate 300, and a gap 304 is formed on a side wall of the word line (or gate structure) 302. . A first dielectric layer 306 is formed on the semiconductor substrate 300 to cover the word line (or gate structure) 302, the spacer 304, and other exposed semiconductor substrates 300. The first dielectric layer 306 not only covers the foregoing The structure also provides a flat surface to facilitate the subsequent lithography process. A first photoresist layer 308 is formed on the first dielectric layer 306, and the first lithography process is performed. In a fully focused or slightly defocused state (for example, the defocused state is -0.2 microns), a photomask For example, the pattern of the alternating phase shift photomask shown in FIG. 1 above is transferred onto the first photoresist layer 308, so that the first photoresist layer 308 also has a bit line contact window opening pattern 308a in contact with the terminal. Window opening pattern 308b. Through the pattern on the first photoresist layer 308, the first dielectric layer 3 (1 :: is etched to form a bit line and a terminal opening in the first dielectric layer 306 and is in the opening. A conductive material is inserted to form a bit line contact and a terminal contact 312. The first dielectric layer 306 is covered with a second layer 314, and the second dielectric layer 314 is covered with a second photoresist layer 316, wherein The second dielectric layer 3! 4 is the same as the first dielectric layer, and also has a flat surface. The second lithography process using the alternating phase-shifting photomask described in FIG. 1 is performed at a large defocus. The state (for example, the defocus state is +0.4 micron), the paper size is 7. The paper size is applicable to the Chinese National Standard (CNS) A4 specification (210 X 297 mm) ----------- ^ ---- ---- Order --------- line (I (Please read the note ^^ on the back before filling out this page) Printed by the Consumer Cooperatives of the Intellectual Property Bureau of the Ministry of Economic Affairs 4 632 5228twf.doc / 008 A7 B7 i. &Amp; Description of the Invention The element line contact window opening pattern 316a is transferred to the second photoresist layer 316. Note that there is no pattern of terminal contact window openings on the second photoresist layer 316. Therefore, this Ming provides a method of using an alternating phase shift mask, which can form different patterns on the wafer under different exposure conditions, so it can be used in different lithography processes to save the number of masks. Because of the design The manufacturing process of the photomask pattern is complicated and requires more cost, so saving the use of one photomask can greatly save the cost of the entire semiconductor process. In addition, the invention combines the pattern design of the bit line contact window and the terminal contact window. On the same photomask, the bit line contact window pattern and the terminal contact window pattern can be exposed at the same time on the first photoresist layer, and there is no need to worry about the formation of the bit line contact window pattern and the terminal contact window pattern. The problem of quasi-error occurs. Although the present invention has been disclosed as above with a preferred embodiment, it is not intended to limit the present invention. Any person skilled in the art can make various changes without departing from the spirit and scope of the present invention. Changes and retouching, so the scope of protection of the present invention shall be determined by the scope of the attached patent application. ----- II [I-^^ -------- Order ----- ----line {(Please read the notes on the back before filling out this page) Printed by the Consumer Cooperatives of the Intellectual Property Bureau of the Ministry of Economic Affairs 8 This paper size applies to China National Standard (CNS) A4 (210x297 mm)