461029 五、發明說明（1) 發明領域. 本發明係有關於一種半導體之製程’特別是有關於— 種在單一化學清洗槽中進行化學清洗的同時形成一閘極氧 化層預層（P r e - 1 a y e r )之方法。 發明背景： ULS I製程對半導體基板表面的乎滑性、微粒子及污 染物如金屬及有機殘留物等等之要求的嚴謹度都遠甚於 VLSI製程。例如ULSI製程的要求必須達到小於5nm的閘極 氧化層、金屬或金屬石夕化物接觸、高品質的遙晶層，當元 件尺寸縮到次微米級，極清洗之表面更要求包括：沒有任 何的粒子、有機污染物、金屬污染物。 其次表面微链度（m i c r 〇 r 〇 u g n e s s)及天然氧化層 (native oxide)也是不允許的。例如當.製程是q μ#以製 程’閘極氧化層約為1 0 0埃’而在0 · 1/z m製程時閘極氧化 層就約4 0埃左右而已，表面微糙度就應達到原子級。天 氧化層是另一影響閘極氧化層厚度控制的不續定因子，^ 然氧化層常會選擇性阻礙化學氣相沉積，也阻礙遙晶成天 長0 著名的RCA清洗程序自1 9 70年代即已廣.範應用於石夕晶 4 6 102 9 .五、發明說明（2) 圓的清洗，並經過不斷的改進以符合於ULS I製程的要求。 其次，相關支援設備，包括氧含量零的去離子水，純淨氣 體輸送系統、特殊的設計以避免粒子生成，以及引用超高 聲波振波清洗（megasonic cleaning;轉換子之輸出頻率 高達8 5 0至9 0 0 kHZ)以促使微粒解離都是因應ULSI製程的要 求。RCA清洗程序包含兩個順序進行的清洗程序如 ΝΗ40Η-Η 20 2-Η 20(— 般稱為第一標準清洗（standard c 1 e a n i n g 1 (S C - 1 )，在 7 0至 8 0°C 組成比為 1 : 1 : 5至 1 : 2 : 7。另一種清洗稱為第二標準清洗（s t a n d a r d c 1 e a n i n g 2 ( S C - 2 )，在 7 0至 8 0°C 組成比為 H C 1 : H 20 2-H 20 = 1 : 1 : 6至1 : 2 : 8。這兩種清洗都以過氧化氫為 基礎’在高酸驗值pH值的（SC -1 )以氧化的方式可有效去除 有機污染物及粒子。而低p Η值的（S C - 2 )則借助於形成可溶 性錯合物以去除金屬污染物的吸附。SC - 1清洗佐以平行晶 圓表面之超高聲波振波清洗更是一種可以在低於4 〇°c以下 的溫.度’就可有效除去晶圓表面的有_機或_者無機微粒。 為了提供滿足ULSI清洗度的需求，傳統方法在長閘極 氧化層之刖’係以R C A清洗程序為基礎_ ’而發展數種清洗 程序以去除天然氧化層’以下係幾種常用的方法，例如， 其中之第一種係在SCI清洗後再進入稀鹽酸中浸潰，之 後’再吹乾’第二種係在SC1清洗後再進入稀鹽酸和氫氟 酸槽中浸潰’之後’再將晶圓移至含臭氧的去離子水及鹽 酸液槽浸潰若干秒再吹乾。 46 102 9 __----- - ' ' ' —-- 五、發明說明（3) 另一種傳統方法則捨棄傳統SC 1清洗程序，直接以如 下步驟清洗，首先晶圓就以含臭氧濃度約5-1 OOppm的去離 子水（通常約5 0至1 0 0 p p m及鹽酸液槽浸潰，再轉入稀鹽酸 和氫氟酸槽中浸潰’之後，再將晶圓移至含臭氧的去離子 水及鹽酸液槽浸潰若干秒再吹乾。這種利用臭氧解離之去 離子水清洗的機制如下：由於臭氧解離於去離子水時就會 變成強氧化劑而分#有機不純物微粒。臭氧解離之去離子 水清洗具有低溫、簡單且減少化學藥品之清耗的清洗程 序。不過這種含臭氧的清洗程序已有研究顯示將使天然氧 化層更易成長，不只是隨溫度升高而增加，且更隨臭氧濃 度之增加而增加。因此上述含臭氧的清洗程序，最後會再 浸入臭氧解離之去離子水及鹽酸液中處理以避免天然氧化 層的再生。 上述之清洗程序，主要都是在去除有機、無機微粒·子 及除去天然氧化層，並防止天然氧化層之再生，本發明則 將提供另一種選擇，以形成品質良好的化學沉積氧化層作 為預層。 發明目的及概述： 本發明之一目的係提供一種晶圓化學清洗之方法。461029 V. Description of the invention (1) Field of the invention. The present invention relates to a process for a semiconductor, and in particular, to a method for forming a gate oxide layer (P re- 1 ayer). Background of the Invention: The ULS I process has stricter requirements on the surface of semiconductor substrates, such as the smoothness of particles, particles and contaminants such as metals and organic residues, than the VLSI process. For example, the requirements of the ULSI process must reach less than 5nm of the gate oxide layer, metal or metal oxide contact, high-quality telecrystal layer. When the component size is reduced to the sub-micron level, the extremely cleaned surface requirements include: no Particles, organic pollutants, metal pollutants. Secondly, the surface microchain degree (m i c r 〇 r 〇 u g n e s s) and natural oxide (native oxide) are not allowed. For example, when the manufacturing process is q μ #, the process of the gate oxide layer is about 100 angstroms, and the gate oxide layer is only about 40 angstroms when the 0.1 · zm process is performed, and the surface roughness should reach Atomic level. The natural oxide layer is another indefinite factor that affects the thickness control of the gate oxide layer. However, the oxide layer often selectively inhibits chemical vapor deposition, and it also hinders the growth of telecrystals. The famous RCA cleaning program has been in existence since the 1970s. It has been widely used in Shi Xijing 4 6 102 9 V. Description of the invention (2) The cleaning of the circle has been continuously improved to meet the requirements of the ULS I process. Secondly, related supporting equipment, including deionized water with zero oxygen content, pure gas delivery system, special design to avoid particle generation, and the use of ultra-high sonic cleaning (megasonic cleaning; the output frequency of the converter is as high as 8 50 to 9 0 0 0 KHZ) to promote the dissociation of particles are in accordance with the requirements of the ULSI process. The RCA cleaning program includes two sequential cleaning programs such as ΝΗ40Η-Η 20 2-Η 20 (— generally called the first standard cleaning (standard c 1 eaning 1 (SC-1)), which is composed of 70 ° C to 80 ° C. The ratio is 1: 1: 5 to 1: 2: 7. Another cleaning is called the second standard cleaning (standardc 1 eaning 2 (SC-2)), and the composition ratio is HC 1: H 20 at 70 to 80 ° C. 2-H 20 = 1: 1: 6 to 1: 2: 8. Both of these cleanings are based on hydrogen peroxide, which can effectively remove organics by oxidation at high acid pH (SC -1). Contaminants and particles. And the low p Η value (SC-2) removes the adsorption of metal contaminants by forming soluble complexes. SC-1 cleaning is supplemented by ultra-high sonic vibration parallel to the wafer surface. It can effectively remove organic or inorganic particles on the wafer surface at a temperature below 40 ° C. In order to meet the requirements of ULSI cleanliness, the traditional method is to use a long gate oxide layer. Zhi 'is based on the RCA cleaning program_' and developed several cleaning programs to remove the natural oxide layer 'The following are several commonly used Method, for example, the first one is immersed in dilute hydrochloric acid after SCI cleaning, and then 'blow dry', the second is immersed in dilute hydrochloric acid and hydrofluoric acid tank after SC1 cleaning. After that, the wafer was moved to a bath containing ozone-containing deionized water and hydrochloric acid for several seconds, and then dried. 46 102 9 __------'' '--- V. Description of the invention (3) A traditional method is to abandon the traditional SC 1 cleaning procedure and directly clean it by the following steps. First, the wafer is immersed in a deionized water with an ozone concentration of about 5-1 to 100 ppm (usually about 50 to 100 ppm and a hydrochloric acid bath). , And then transferred to dilute hydrochloric acid and hydrofluoric acid tanks for dipping, and then the wafers were moved to ozone-containing deionized water and hydrochloric acid liquid tanks for dipping for a few seconds and then dried. This deionized water using ozone dissociation The cleaning mechanism is as follows: As ozone dissociates in deionized water, it becomes a strong oxidant and separates organic impurities. The ozone dissociated deionized water cleaning has a low temperature, simple cleaning process that reduces the consumption of chemicals. But this kind of cleaning Studies on ozone-containing cleaning procedures have shown that natural The chemical layer grows more easily, not only increases with the increase of temperature, but also increases with the increase of ozone concentration. Therefore, the above-mentioned ozone-containing cleaning procedure will be immersed in deionized water and hydrochloric acid solution dissociated with ozone to avoid natural Regeneration of the oxide layer. The above cleaning procedures are mainly to remove organic and inorganic particles and particles, and to remove the natural oxide layer, and prevent the regeneration of the natural oxide layer. The present invention will provide another option to form a good quality chemical An oxide layer is deposited as a pre-layer. Objects and Summary of the Invention: One object of the present invention is to provide a method for chemical cleaning of wafers.
461029 五、發明說明（4) ——--- 仆與^ ί ί 3的係提供一種在晶圓清洗過程中形成 化子積氧化層以防止天然氧化層生成之方法。 本發明係一種以化學溶液形成 法.，至少包含下列歩驟.發λ 化禮預廣之方 氣體之去離子水溶液'以 曰基板於^溶有臭氧 著將該去離子水排出.隨仃$ 微粒之氧化作用，接 間極氧化層例如，首Hi刀成四個階段下沉積-氫氟酸溶液於晶圓清洗槽息酸，奋液他殽a)、 皿酸溶液及氣氣酸溶游：曾痒 下降至接近零之下，（階段w，π合液/辰度比例先後 半導體晶圓上。 /儿閘極氧化層預層於 發明詳細說明： 有鑑於如發明背景所述，傳統清洗程 清洗程序或改良的RCA清洗程序或者以氧=f是RCA 洗程序，都是以除去天然氧化層為主，再的清 保護膜以防止在高溫的熱氧化製程長間極形成 天然氧化層。本發明提出另一種有別於傳統則再生成 '' 法之新技 461029 五、發明說明（5) 術，即利用清洗程序時同時形成一極薄的化學沉積氧化 層，以做為閘極氧化層之預層。如此將可以更可靠地防止 天然氧化層的再生成。此外為更能確保每一晶圓沉積之化 學沉積氧化層厚度的穩定性，本發明採用的方式是所有的 清洗程序都在同一清洗槽中進行。以下的說明將佐以圖示 以使本發明更易被了解。 本發明的清洗程序如下：首先載入半導體晶圓於去離 子水溶液晶圓清洗槽處理，去離子水溶液溶解約1 -1 0 ppm 之臭氧（典型值約5-1 0ppm)臭氧解離於去離子水時變成強^ 氧化劑而分解有機不純物微粒，接著，將晶圓清洗槽内之 去離子水溶液排出；隨後，再注入含氫氟酸及鹽酸溶液於 同一晶圓清洗槽，以去除金屬微粒及有機污染物，以一較 佳的實施例而言，氫氟酸及鹽酸溶液之重量濃度分別約為 0 . 1 - 0 . 5 °/。及2 0 - 6 0 %，處理時間約6 0 - 2 4 0 0秒；接著，再排 出晶圓清洗槽内之氮氟酸及鹽酸溶液。 — 最後，利用鹽酸/氫氟酸八溶解臭氧的去離子水）溶液 進行化學沉積氧化膜以沉積極薄的化學沉積氧化膜，請同 ( 時參考圖一的濃度變化曲線，濃度變化曲線可分為四階段 說明，首先A階段開始，注入鹽酸溶液於晶圓清洗槽内， 以一較佳的實施例而言，鹽酸溶液之重量濃度約由 0.5-50 %增加至約10-50%，鹽酸溶液可用以去除金屬微 粒，有機污染物；隨之，進入B階段，再加入氫氟酸溶461029 V. Description of the invention (4) —————— The servant ^ ί ί 3 provides a method for forming a chemical oxide layer in the wafer cleaning process to prevent the formation of a natural oxide layer. The present invention is a method for forming a chemical solution. The method includes at least the following steps. A deionized aqueous solution of a lambda gas is used to discharge the deionized water by dissolving ozone in a substrate. Oxidation of particles, followed by a layer of polar oxide. For example, the first Hi-knife is deposited in four stages-hydrofluoric acid solution is dissolved in the wafer cleaning bath. Fennel is confused with a), dish acid solution and gas acid solution. : Itch has fallen to below zero, (stage w, π junction / Chen ratio on the semiconductor wafer. / Gate oxide layer pre-layer in the invention detailed description: In view of the traditional cleaning as described in the background of the invention, Process cleaning program or modified RCA cleaning program or oxygen = f is the RCA cleaning program, which mainly removes the natural oxide layer, and then clears the protective film to prevent the formation of a natural oxide layer during the long-term thermal oxidation process. The present invention proposes another new technique which is different from the traditional regeneration method 461029. 5. Description of the invention (5) technique, that is, a very thin chemically-deposited oxide layer is formed at the same time as the gate oxidation during the cleaning process. Layer of the pre-layer. Relying on the ground to prevent the regeneration of the natural oxide layer. In addition, in order to ensure the stability of the thickness of the chemically deposited oxide layer deposited on each wafer, the method adopted by the present invention is that all cleaning procedures are performed in the same cleaning tank. The following The description will be illustrated to make the present invention easier to understand. The cleaning procedure of the present invention is as follows: First, the semiconductor wafer is loaded in a deionized aqueous solution wafer cleaning tank, and the deionized aqueous solution dissolves about 1-10 ppm of ozone ( (Typical value is about 5-10 ppm) When ozone is dissociated in deionized water, it becomes a strong ^ oxidant to decompose organic impurities. Then, the deionized aqueous solution in the wafer cleaning tank is discharged; subsequently, the solution containing hydrofluoric acid and hydrochloric acid is injected In the same wafer cleaning tank to remove metal particles and organic pollutants, in a preferred embodiment, the weight concentrations of hydrofluoric acid and hydrochloric acid solutions are about 0.1-0.5 ° / and 2 0-60%, the processing time is about 60-240 seconds; then, the fluorinated acid and hydrochloric acid solution in the wafer cleaning tank are discharged. — Finally, the deionization of ozone is dissolved with hydrochloric acid / hydrofluoric acid eight. ) The solution is chemically deposited on the oxide film to deposit a very thin chemically deposited oxide film. Please refer to the concentration change curve in Figure 1. The concentration change curve can be divided into four stages. First, start with the A stage. Inject the hydrochloric acid solution into the wafer. In the cleaning tank, in a preferred embodiment, the weight concentration of the hydrochloric acid solution is increased from about 0.5-50% to about 10-50%. The hydrochloric acid solution can be used to remove metal particles and organic pollutants; Stage, then add hydrofluoric acid
第8頁 4 6 1 0 2 9 五、發明說明（6) 液。鹽酸在B階段繼續加入以維持約相同的重量濃度，氫 氟酸溶液則增加至溶液之重量濃度達0. 4-0. 5%為止。 仍請參考圖一，當C階段開始，鹽酸不再增加，而氳 氟酸溶液仍繼續增加，同時也添加含臭氧的去離子水，臭 氧溶度逐漸增加至1 -7ppm，氫氟酸溶液濃度則增加至約0 . 4-0. 5%為止。在C階段由於鹽酸濃度因氫氟酸溶液及含臭 氧的去離子水而逐步下降。最後，D階段開始，氫氟酸溶 液中止加入，含臭氧的去離子水一直增加至臭氧的濃度達 5 - 1 0 p p m。同時鹽酸或氫氟酸溶液比例也逐漸降低。以形 成化學沉積氧化層做為閘極氧化層的預層。以一較佳的實 施例而言，為形成厚度約1 0 - 3 0埃的化學沉積氧化預層， 上述之A階段約1 0 - 1 8 0 0秒，而B階段約1 0 - 1 8 0 0秒，C階段 約1 0 - 2 4 0 0秒，D階段約1 0 - 2 4 0 0秒。 本發明具有以下幾個優點： (1)由於本發明使用相對於傳統RCA清洗程序更低濃 度之化學液，因此，可以減少對環保的衝擊。例如，不但 在注入含氫氟酸及鹽酸溶液於晶圓清洗槽，以去除金屬微 粒子及有機微粒子之附著時濃度較低，且沉積一閘極氧化 層預層於晶圓之程序中氫氟酸及鹽至酸濃度並降至零。 (2 )本發明使用的臭氧濃度約在1 0 ppm以下，相較於 採用臭氧濃度約5 0至1 0 0 ppm之傳統方法，要明顯低很多， 461029 五、發明說明（7) 因此，成本降低。 (3)本發明使用小型單一的清洗槽，在一批量處理完 畢（至多二批量，視清洗槽容量而定）後就將先前的清洗液 排出，因此可以更保證每一批量晶圓之處理品質，特別是 閘極氧化層之預層厚度可以更精準控制。 (4)由於沉積了化學沉積氧化層在晶圓上，因此可以比傳 統方法更能防止天然氧化層的再形成。 本發明僅以較佳實施例說明如上，並非用以限定本發 明之申請範圍；凡熟習該項技藝人士，在未脫離本發明之 精神下，當可作些許改變或修飾，其專利保護範圍均應包 含在下述之申請專利範圍内。Page 8 4 6 1 0 2 9 V. Description of the Invention (6) Liquid. 4-0. 5% 至。 Hydrochloric acid continued to be added in the B stage to maintain about the same weight concentration, the hydrofluoric acid solution was increased to the solution's weight concentration of 0. 4-0. 5% so far. Please still refer to Figure 1. When the C phase begins, the hydrochloric acid will not increase, and the fluorenic acid solution will continue to increase. At the same time, ozone-containing deionized water will be added. The ozone solubility will gradually increase to 1-7 ppm, and the concentration of the hydrofluoric acid solution. It increased to about 0.4-0.5%. In stage C, the concentration of hydrochloric acid gradually decreases due to the hydrofluoric acid solution and deionized water containing ozone. Finally, at the beginning of stage D, the addition of the hydrofluoric acid solution was stopped, and the deionized water containing ozone was increased until the ozone concentration reached 5-10 p p m. At the same time, the proportion of hydrochloric acid or hydrofluoric acid solution gradually decreased. The formation of a chemically deposited oxide layer serves as a pre-layer for the gate oxide layer. In a preferred embodiment, in order to form a chemically-deposited oxidation pre-layer having a thickness of about 10 to 30 angstroms, the above-mentioned stage A is about 10 to 1 800 seconds, and the stage B is about 10 to 18 0 seconds, C phase is about 10-2 4 0 0 seconds, D phase is about 10-2 4 0 0 seconds. The present invention has the following advantages: (1) Since the present invention uses a chemical solution having a lower concentration than the conventional RCA cleaning procedure, the impact on environmental protection can be reduced. For example, not only the concentration of hydrofluoric acid and hydrochloric acid solution in the wafer cleaning tank to remove the adhesion of metal particles and organic particles is low, but also a gate oxide layer is deposited on the wafer in the process of hydrofluoric acid. And salt to acid concentration and drop to zero. (2) The ozone concentration used in the present invention is below 10 ppm, which is significantly lower than the traditional method using ozone concentration of about 50 to 100 ppm. 461029 V. Description of the invention (7) Therefore, the cost reduce. (3) The present invention uses a small single cleaning tank, and the previous cleaning liquid is discharged after one batch processing (up to two batches, depending on the capacity of the cleaning tank), so the processing quality of each batch of wafers can be more guaranteed In particular, the pre-layer thickness of the gate oxide layer can be controlled more precisely. (4) Since the chemically-deposited oxide layer is deposited on the wafer, it is possible to prevent the re-formation of the natural oxide layer more than the conventional method. The present invention is only described in the preferred embodiments above, and is not intended to limit the scope of application of the present invention. Those skilled in the art can make some changes or modifications without departing from the spirit of the present invention. The scope of patent protection is all It should be included in the scope of patent application described below.
第10頁 461029 圖式簡單說明 本發明的較佳實施例將於往後之說明文字中輔以下列圖形 做更詳細的闡述： 圖一顯示依據本發明之方法形成化學沉積閘極氧化層 預層時各相關濃度變化表。Page 461029 The diagram briefly illustrates the preferred embodiment of the present invention and will be explained in more detail in the following explanatory text with the following figures: Figure 1 shows the formation of a chemically deposited gate oxide pre-layer according to the method of the present invention Table of related concentration changes.