4 I 4 1 tvvt'.doc/〇〇8 A7 B7 五、發明説明（j ) 本發明是有關於一種積體電路的製造法，且特別是有 關於一種淺溝渠隔離區（Shallow Trench Isolation，STI) 的製造方法 元件隔離區係用以防止載子（Carrier)通過基底而在 相_的元件間移動之用。典型的元件隔離區係形成於稠密 的半導體電路，比如是動態隨機存取記憶體（DRAM)中， 其相鄰的場效電晶體（Field Effect Transistor，FET)之間， 藉以減少由場效電晶體產生的漏電流（Leakage)現象。 典型形成元件隔離區的方法係採用局部區域氧化技術 (LOCOS)。然而，採用局部區域氧化的方式具有應力產 生的問題與場隔離結構周圍鳥嘴區（Bird’s Beak)的形成 等缺點。其中，特別是鳥嘴區的形成，使得在小型的元件 上^以LOCOS方式所形成之場隔離結構並不能做有效地 隔離，所以在高密度（High Density)元件中，必須以較 易於調整大小的淺溝渠隔離方式所形成之元件隔離結構來 取代。 淺溝渠隔離法是一種利用非等向性蝕刻方法在半導體 基底中形成溝渠，然後在溝渠中塡入氧化矽，以形成元件 之隔離區的技術。由於淺溝渠隔離法所形成之場隔離區具 有可調整大小（Scaleable)的優點，並且可避免傳統區域 氧ft法隔離技術中鳥嘴侵蝕（BircTs Be^k Encroachment) 的缺點，因此，對於深次微米（Deep Sub-Micron)的互補 式金氧半導體（CMOS)製程而言，是一種較爲理想與的 隔離技術。 3 ^ '*：標今(('NS ) 見柏（210X 297公釐） (对先閱讀背面之注項再填寫本頁) ,?τ rY. 4 1 4 I twf.doc/00 8 A7 B7 五、發明説明（i) 第1A圖至第1B圖是習知一種淺溝渠隔離區之製造流 程ή剖面圖。請參照第1A圖，典型的方法係在基底100 上形成一層圖案化的墊氧化層102與氮化矽層104，再以 氮化矽層104爲蝕刻罩幕，在基底1〇〇中蝕刻出溝渠106。 接著，再以乾式氧化法，使溝渠106所裸露之基底100的 表面氧化而形成一層襯氧化層108。其後，於基底100上 覆蓋氧化矽層110,以覆蓋氮化矽層104,並將溝渠106 塡滿。 其後，請參照第1Β圖，以氮化矽層104作爲硏磨終 止詹，利用化學機械硏磨法去除多餘的氧化層110，留下 溝渠106之中的氧化層110。其後，去除氮化矽層104， 並以氫氟酸溶液去除墊氧化層102，以使留下之氧化層110 在基底100中形成隔離區112。 在上述淺溝渠隔離區的製程中，由於塡入溝渠106之 中的氧化矽層110通常是以化學氣相沈積法形成者，故其 結構較爲鬆散，而以熱氧化法所形成之墊氧化層102之結 構較爲緻密，因此，在以氫氟酸溶液去除墊氧化層102的 濕武蝕刻製程中，塡入溝渠106的氧化矽層110之蝕刻速 率會較高於墊氧化層102者。又，以氫氟酸溶液浸蝕的方 式係屬於等向性蝕刻，位於溝渠106之頂端邊角處（Top Corner) 114的氧化矽層110，易因爲氫氟酸的側向蝕刻， 而使最終形成之隔離區112產生凹陷116的現象，導致溝 渠1〇6之頂端邊角處114裸露出來，使得後續形成之閘極 氧化層在頂端邊角處114的厚度較薄於基底100之其他主 . 4 (誚先閱讀背面之注意事項再填寫本頁) 訂 本紙尺度谪川屮國阀家標蜱（（，ns ) Λ4規招（210Χ297公釐） 4l4lt\vf.doc/008 A7 B7 五、發明説明（$ ) 動區上所形成者，而造成元件產生頸結效應。 \J 有鑑於此，本發明的目的就是在提供一種淺溝渠隔離 區的製造方法，避免溝渠之頂端邊角處附近之塡充物質由 於側向蝕刻所造成的凹陷現象，以防止井結效應的發生。 ‘根據本發明之目的，提出一種淺溝渠隔離區的製造方 法，此方法係在基底上形成一層墊氧化層與一層罩幕層， 以在基底中定義出溝渠，之後，以濕式熱氧化法，在攝氏 溫度950度至1180度之間進行襯氧化層的成長製程。由 於以此條件下所施行之熱製程除了可使溝渠所裸露的矽基 底表面產生氧化，亦可以使罩幕層之表面產生氧化，因此， 所形成之襯氧化層不僅覆蓋於溝渠之表面，亦將延伸覆蓋 至罩幕層之側壁與表面上。其後，再於溝渠中塡入塡充物 質；並將其平坦化，最後，再去除罩幕層與墊氧化層。 依照本發明實施例所述，本發明所形成之襯氧化層爲 本發明的重要特徵，由於襯氧化層所覆蓋的範圍係由溝渠 之表面延伸至罩幕層的側壁與表面之上，因此，在將元件 平坦化、並去除罩幕層之後。位於罩幕層之側壁上的襯氧 化層，將因爲與罩幕層之蝕刻率不同而被保留下來。由於 襯氧化層其結構的緻密度較高於塡充於溝渠的塡充物質’ 在後續以氫氟酸溶液去除墊氧化層的過程中’其蝕刻速率 較低於塡充物質，因此，位於罩幕層之側壁上的襯氧化層 可用以保護溝渠之頂端邊角處附近之塡充物質’避免側向 蝕刻而造成溝渠之頂端邊角處附近之塡充物質產生凹陷的 現象。 5 本紙张尺州家K—( (，NS ) A4規格（210X297公釐） (許先閱讀背面之注意事項再填寫本頁) 訂 4 I 4 I twf.doc/008 A7 B7 五、發明説明（α) 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1B.圖是習知一種淺溝渠隔離區之製造 流程的剖面示意圖；以及. 第2A圖至第2F圖，其繪示依照本發明一較佳實施例’ 一種淺溝渠個隔離區·之製造流程的剖面示意圖Λ 圖式之標記說明= 100，200 基底 102、202、202a 墊氧化層 104、204、204a 罩幕層 106、206 溝渠 108、212、212a 襯氧化層 110 氧化層 • 112 隔離區 114、214 溝渠之頂端邊角處 116 凹陷 208 凹陷區域 210 突起區域 216 罩幕層之側壁 218 罩幕層之表面 220 > 220a 塡充物質 .實施例一 6 本紙俅尺度读W中國1¾¾:標等（rNS)A4規招（210X297公釐） Μ— (对先閱讀背面之泣意事項存填寫本筲)4 I 4 1 tvvt'.doc / 〇〇8 A7 B7 V. Description of the invention (j) The present invention relates to a method for manufacturing integrated circuits, and in particular, to a shallow trench isolation area (Shallow Trench Isolation, STI). The manufacturing method of the component isolation region is used to prevent carriers (Carrier) from moving through the substrate between the phase components. A typical device isolation region is formed in a dense semiconductor circuit, such as a dynamic random access memory (DRAM), and adjacent field effect transistors (FETs) are used to reduce the field effect current. Leakage phenomenon caused by crystal. A typical method of forming an element isolation region is a local area oxidation technique (LOCOS). However, the use of localized area oxidation has the disadvantages of stress generation and the formation of Bird's Beak around the field isolation structure. Among them, the formation of the bird's beak area makes the field isolation structure formed by the LOCOS method on small components not effective for isolation. Therefore, in high density (High Density) components, it must be easier to adjust the size. Element isolation structure formed by the shallow trench isolation method. Shallow trench isolation is a technique that uses a non-isotropic etching method to form a trench in a semiconductor substrate, and then inserts silicon oxide into the trench to form an isolation region for the device. Because the field isolation area formed by the shallow trench isolation method has the advantages of being scalable, and can avoid the shortcomings of BircTs Be ^ k Encroachment in the traditional regional oxygen ft method isolation technology, Micron (Deep Sub-Micron) complementary metal-oxide-semiconductor (CMOS) process is an ideal isolation technology. 3 ^ '*: Mark this ((' NS) See Bai (210X 297mm) (read the note on the back before filling out this page),? Τ rY. 4 1 4 I twf.doc / 00 8 A7 B7 V. Description of the Invention (i) Figures 1A to 1B are cross-sectional views of a conventional manufacturing process for a shallow trench isolation zone. Please refer to Figure 1A. A typical method is to form a patterned pad oxidation on the substrate 100. The layer 102 and the silicon nitride layer 104, and the silicon nitride layer 104 is used as an etching mask, and the trench 106 is etched in the substrate 100. Then, the surface of the substrate 100 exposed by the trench 106 is dried by a dry oxidation method. Oxidation forms a lining oxide layer 108. Thereafter, a silicon oxide layer 110 is covered on the substrate 100 to cover the silicon nitride layer 104 and the trench 106 is filled. Thereafter, please refer to FIG. The layer 104 is used as a honing stop. The chemical oxide honing method is used to remove the excess oxide layer 110, leaving the oxide layer 110 in the trench 106. Thereafter, the silicon nitride layer 104 is removed, and the pad is removed with a hydrofluoric acid solution. The oxide layer 102 is oxidized so that the remaining oxide layer 110 forms an isolation region 112 in the substrate 100. In the above-mentioned shallow trench isolation region process, Since the silicon oxide layer 110 that has penetrated into the trench 106 is usually formed by a chemical vapor deposition method, its structure is relatively loose, and the structure of the pad oxide layer 102 formed by the thermal oxidation method is relatively dense. Therefore, In the wet etching process for removing the pad oxide layer 102 with a hydrofluoric acid solution, the etching rate of the silicon oxide layer 110 penetrating the trench 106 is higher than that of the pad oxide layer 102. In addition, the method is etched with a hydrofluoric acid solution. It is an isotropic etch. The silicon oxide layer 110 located at the top corner 114 of the trench 106 is susceptible to the phenomenon of depression 116 caused by the lateral etching of hydrofluoric acid. As a result, the top corner 114 of the trench 106 is exposed, making the thickness of the gate oxide layer 114 formed later at the top corner 114 thinner than other substrates of the substrate 100. 4 (诮 Please read the precautions on the back before filling (This page) The size of the paper on the basis of the standard paper (谪, ns) Λ4 regulations (210 × 297 mm) 4l4lt \ vf.doc / 008 A7 B7 V. Description of the invention ($) And cause the knot effect of the component. \ J The purpose of the present invention is to provide a method for manufacturing a shallow trench isolation zone, to avoid the depression phenomenon caused by lateral etching of the filling material near the top corners of the trench, so as to prevent the occurrence of the well-knot effect. The purpose of the invention is to provide a method for manufacturing a shallow trench isolation zone. This method forms a pad oxide layer and a mask layer on the substrate to define the trench in the substrate. Then, a wet thermal oxidation method is used at Celsius. The growth process of the lining oxide layer is performed at a temperature between 950 degrees and 1180 degrees. Since the thermal process performed under this condition can not only oxidize the surface of the silicon substrate exposed by the trench, but also oxidize the surface of the mask layer, the lining oxide layer formed not only covers the surface of the trench, but also Cover the extension to the side walls and surface of the mask layer. After that, the filling material is poured into the trench; it is flattened, and finally, the mask layer and the pad oxide layer are removed. According to the embodiments of the present invention, the lining oxide layer formed by the present invention is an important feature of the present invention. Since the range covered by the lining oxide layer extends from the surface of the trench to the side walls and the surface of the cover layer, therefore, After flattening the components and removing the mask layer. The lining oxide layer on the side wall of the mask layer will be retained because the etching rate is different from that of the mask layer. Because the lining oxide layer has a denser structure than the filling material filled in the trench, the etching rate is lower than that of the filling material during the subsequent removal of the pad oxide layer with a hydrofluoric acid solution. The lining oxide layer on the side wall of the curtain layer can protect the filling materials near the top corners of the trench to avoid the phenomenon that the filling materials near the top corners of the trench are depressed by side etching. 5 This paper ruler K — ((, NS) A4 size (210X297 mm) (may read the precautions on the back before filling out this page) Order 4 I 4 I twf.doc / 008 A7 B7 V. Description of the invention ( α) In order to make the above and other objects, features, and advantages of the present invention more comprehensible, the following describes the preferred embodiments in detail with the accompanying drawings as follows: Brief description of the drawings: Section 1A Figures to 1B. Figures are cross-sectional schematic diagrams of a conventional manufacturing process for a shallow trench isolation area; and Figures 2A to 2F, which illustrate a shallow trench isolation area according to a preferred embodiment of the present invention. Schematic diagram of the cross-section of the manufacturing process Λ Marking description of the diagram = 100, 200 substrate 102, 202, 202a pad oxide layer 104, 204, 204a cover layer 106, 206 trench 108, 212, 212a oxide layer 110 oxide layer 112 Isolation areas 114, 214 Top corners of the trench 116 Sag 208 Sag area 210 Raised area 216 Side wall of the cover layer 218 Surface of the cover layer 220 > 220a Filling material. : Standard class (rNS) A4 regulations (210X297 mm ） Ｍ— (Please fill in this note for the weeping matter on the back of the reading first)
*1T 妗浚部屮*標1-^β-τ消於合印擎 4 I 4 11 w f. d 〇 c / 0 0 8 A7 B7 五、發明説明（t) 請參照第2A圖至第2F圖，其繪示依照本發明較佳實 施例之一種淺溝渠個隔離區之製造流程的剖面示意圖。 •首先，請參照第2A圖，在所提供的基底200上形成 一層墊氧化層202 ’以在製程中保護基底200的表面’其 典型的形成方法例如爲熱氧化法。接著，於墊氧化層202 上，形成罩幕層204，此罩幕層204則可以在後續於基底 200中形成淺溝渠之製程中作爲蝕刻罩幕之用，並且在後 續的平坦化製程中作爲硏磨的終點，因此，其材質與基底 200之材質具有不同的蝕刻率，且其硬度需大於淺溝渠隔 離區之材質。當基底200爲矽、淺溝渠隔離區之材質爲氧 化矽時’較佳的罩幕層204之材質包括氮化矽，氮氧化矽、 複晶矽或非晶矽’其形成的方法例如爲化學氣相沈積法。 接著’請參照第2B圖，定義罩幕層204與墊氧化層 202’以使之轉爲具有開口的罩幕層2〇4a與墊氧化層2〇2a。 接著’以罩幕層204a與墊氧化層202a爲罩幕，去除部份 的基底200’以在基底200中形成溝渠206。此形成溝渠206 之後的基底200表面可區分爲凹陷區域2〇8與突起區域 210 ’其中’形成溝渠2〇6者係凹陷區域2〇8，而覆蓋罩幕 層204a與墊氧化層202a之基底200的表面則爲突起區域 210。典型形成溝渠206的方法係在罩幕層204表面上形 成一層圖案化的光阻層，然後依序蝕刻罩幕層204與墊氧 化層202 ’以形成具有開口圖案之罩幕^ 2〇4a與墊氧化層 202a。其後’將光阻層剝除，再以罩幕層2〇4&爲硬罩幕， 利用非等向性蝕刻，例如反應性離子蝕刻法，蝕刻基底 7 (¾先閱讀背而之注意事項再填寫本頁)* 1T 妗 妗 部 妗 * 标 1- ^ β-τ is eliminated in the joint printing engine 4 I 4 11 w f. D oc / 0 0 8 A7 B7 V. Description of the invention (t) Please refer to Figure 2A to 2F FIG. Is a schematic cross-sectional view illustrating a manufacturing process of a shallow trench and an isolation region according to a preferred embodiment of the present invention. • First, referring to FIG. 2A, a pad oxide layer 202 'is formed on the provided substrate 200 to protect the surface of the substrate 200 during the manufacturing process. A typical formation method is, for example, a thermal oxidation method. Next, a mask layer 204 is formed on the pad oxide layer 202. This mask layer 204 can be used as an etching mask in the subsequent process of forming shallow trenches in the substrate 200, and can be used as a subsequent planarization process. The end of honing. Therefore, its material has a different etch rate from that of the substrate 200, and its hardness needs to be greater than that of the shallow trench isolation area. When the substrate 200 is silicon and the material of the shallow trench isolation area is silicon oxide, the material of the preferred cover layer 204 includes silicon nitride, silicon oxynitride, polycrystalline silicon, or amorphous silicon. The method for forming the mask layer 204 is, for example, chemical Vapor deposition. Next, please refer to FIG. 2B, and define the mask layer 204 and the pad oxide layer 202 'so that the mask layer 204 and the pad oxide layer 202a have openings. Next, using the mask layer 204a and the pad oxide layer 202a as masks, a part of the substrate 200 is removed to form a trench 206 in the substrate 200. The surface of the substrate 200 after the trench 206 is formed can be divided into a recessed area 208 and a raised area 210. “The trench formation 206 is a recessed area 208, and covers the substrate of the mask layer 204a and the pad oxide layer 202a. The surface of 200 is a protruding area 210. A typical method for forming the trench 206 is to form a patterned photoresist layer on the surface of the mask layer 204, and then sequentially etch the mask layer 204 and the pad oxide layer 202 'to form a mask with an opening pattern ^ 2〇4a and Oxidized layer 202a. After that, the photoresist layer is peeled off, and the mask layer 204 is used as a hard mask. The substrate is etched by anisotropic etching, such as reactive ion etching. (Fill in this page again)
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冬紙依尺及诉川亇阒國家標蜱（（，NS ) Μ坭柁（210X297公釐） 4 14 itwf.doc/008 A7 B7 五、發明説明（4) 200，以將開口的圖案轉移至基底200，而在基底200中形 成溝渠206。 之!後，請繼續參照第2B圖，本發明的重要特徵係在 攝氏溫度950度至1180度之間進行濕式熱氧化製程，以 形成襯氧化層212。由於以此條件下所施行之熱製程具有 極高的氧化特性，除了可使溝渠206所裸露的基底表面產 生氧化，亦可以使罩幕層204a之表面產生氧化，因此， 所形成之襯氧化層212不僅覆蓋於溝渠202之表面，亦將 延伸覆蓋至罩幕層204a之側壁216與表面218之上。濕 式熱氧化製程可以修補形成溝渠206時其蝕刻步驟對基底 200之表面所造成之損壞，而且濕式熱氧化製程所形成之 襯氧化層212，可以防止後續製程中所使用之高能粒子破 壞溝渠206所裸露之基底200表面。濕式熱氧化製程可以 在爐管(Furnace)中通入氫氣進行，亦可以以快速熱氧化製 程(RTO)以執行之，較佳的溫度範圍係在攝氏溫度11〇〇度 至1150度之間，其厚度爲1〇〇埃至350埃。 其後，請參照第2C圖，於基底200表面形成一層塡 充物質220。此塡充物質220塡滿溝渠206，並且覆蓋突 起區域210上方之襯氧化層212的表面218上。典型的塡 充物質220例如爲氧化矽，其形成的方法例如爲常壓化學 氣相沈積法或高密度電漿化學氣相沈積法，較佳的是以四 乙氧基矽烷（TEOS)爲反應氣體源，利用常壓化學氣相 沉積法所形成之TEOS氧化矽材質之塡充物質220。較佳 的作法在形成TEOS氧化矽材質之塡充物晳220之後，可Winter paper according to ruler and v. Chuanxiong national standard tick ((, NS) Μ 坭 柁 (210X297 mm) 4 14 itwf.doc / 008 A7 B7 V. Description of the invention (4) 200 to transfer the opening pattern to The substrate 200, and a trench 206 is formed in the substrate 200. After that, please continue to refer to FIG. 2B. An important feature of the present invention is a wet thermal oxidation process between 950 ° C and 1180 ° C to form a liner oxide. Layer 212. Since the thermal process performed under this condition has extremely high oxidation characteristics, in addition to oxidizing the surface of the substrate exposed by the trench 206, it can also oxidize the surface of the mask layer 204a. Therefore, the formed The lining oxide layer 212 not only covers the surface of the trench 202, but also extends to cover the side wall 216 and the surface 218 of the mask layer 204a. The wet thermal oxidation process can repair the etching step on the surface of the substrate 200 when the trench 206 is formed. Damage caused, and the lining oxide layer 212 formed in the wet thermal oxidation process can prevent high-energy particles used in subsequent processes from damaging the surface of the substrate 200 exposed by the trench 206. The wet thermal oxidation process can be performed on the furnace tube (Furnace) is conducted by passing hydrogen gas, which can also be performed by a rapid thermal oxidation process (RTO). The preferred temperature range is between 1100 degrees and 1150 degrees Celsius, and the thickness is 100 angstroms to 350 angstroms. After that, referring to FIG. 2C, a layer of filling material 220 is formed on the surface of the substrate 200. This filling material 220 fills the trench 206 and covers the surface 218 of the oxide layer 212 above the protruding area 210. Typical The filling material 220 is, for example, silicon oxide, and the formation method thereof is, for example, atmospheric pressure chemical vapor deposition method or high-density plasma chemical vapor deposition method, and tetraethoxysilane (TEOS) is preferred as a reaction gas. Source, using the TEOS silicon oxide filling material 220 formed by atmospheric pressure chemical vapor deposition method. The preferred method is to form the TEOS silicon oxide filling material 220, which can
S (对先閱讀背面之注意事項再填寫本頁}S (Read the notes on the back before filling out this page}
本紙张尺度iij川中國囤家標磾（（，NS > μ規招（2丨〇><297公嫠） 4 1 4 1 twf.doc/008 A7 B7 五、發明说明（）） 以在高溫下，比如在約爲1000°C的溫度條件，進行熱製程 約10〜30分鐘’以使氧化矽之塡充物質220密實化。 (讀先閱讀背而之注意事項再填寫本頁) 其雜’請參照第2D圖，將基底200表面全面性平坦 化。由於罩幕層2(Ma與塡充物質220以及襯氧化層212 具有不同的硏磨速率，較佳的平坦化製程，係以罩幕層204a 爲硏磨終點，經由化學機械硏磨製程，以硏磨去除罩幕層 204表面218上方所覆蓋的襯氧化層212與塡充物質220， 留下凹陷區208上方所覆蓋之襯氧化層212a與塡充物質 22Qa。 經淖部屮Α<?·卑^β-τ·消於合竹 接著’請參照第2E圖，去除罩幕層204a。典型的方 式可以濕式蝕刻法以去除之。當罩幕層204a之材質爲氮 化矽時’較佳的去除方式可以以熱磷酸施行。由於襯氧化 層212a與罩幕層204a具有不同的蝕刻率，在去除罩幕層 204a的過程中’襯氧化層212a並不會遭受蝕刻的破壞， 因此’去除罩幕層2(Ma之後，原本覆蓋於罩幕層204a之 側壁216上的襯氧化層212a仍可被保留下來。由於原來 罩亨層204a之側壁216,係位於溝渠206之頂端邊角處214 的上方’因此’襯氧化層212a在後續的蝕刻製程與淸洗 過程中’將有保護的溝渠206之頂端邊角處214的功能。 最後，請參照第2F圖，去除墊氧化層202a。典型的 方法係以氫氟酸做爲濕式蝕刻製程之蝕刻溶液，以去除位 於突起區域210上方之墊氧化層202a。由於襯氧化層212a 其結構的緻密度較高於塡充於溝渠206的塡充物質22〇a， 在以氫氟酸溶液去除墊氧化層202a的過程中，其蝕刻速 9 本纸张尺度诚川中國國家標碑（（'NS)A4規柏（2丨0x297公釐） 4l41twf.doc/008 A7 B7 五、發明説明（客） 率較低於塡充物質220a，因此，位於罩幕層204a之側壁 218上的襯氧化層212a，亦即位於溝渠206之頂端邊角處 214的襯氧化層2 12a可用以保護溝渠206之頂端邊角處214 其_近之塡充物質220a，以避免側向蝕刻而造成溝渠206 之頂端邊角處214附近之塡充物質220a產生凹陷的現象。 綜合以上所述，本發明之特徵係以濕式熱氧化法，在 攝氏溫度950度至1180度之間進行襯氧化層的成長製程。 由於以此條件下所施行之熱製程除了可使溝渠所裸露的矽 基底表面產生氧化’亦可以使罩幕層之表面產生氧化，因 此，所形成之襯氧化層不僅覆蓋於溝渠之表面，亦將延伸 覆蓋至罩幕層之側壁與表面上。因此，在將元件平坦化、 並去除罩幕層之後。位於罩幕層之側壁上的襯氧化層，將 因爲與罩幕層之蝕刻率不同而被保留下來。由於襯氧化層 其結構的緻密度較高於塡充於溝渠的塡充物質，在後續以 氫氟酸溶液去除墊氧化層的過程中，其蝕刻速率較低於塡 充物質’因此’位於罩幕層之側壁上的襯氧化層可用以保 護溝渠之頂端邊角處附近之塡充物質，避免側向蝕刻而造 成溝渠之頂端邊角處附近之塡充物質產生凹陷的現象。 雖然本發明已以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 v 範圍當視後附之申請專利範圍所界定者爲準。 本紙張尺朗则，肖彳:财（rNS ) h規招⑺flx297公梦） (对先閱讀背面之注意事項存填寫本頁) irStandards of this paper iij Chuan Chinese storehouse standard ((, NS > μ Regulation (2 丨 〇 > < 297)) 4 1 4 1 twf.doc / 008 A7 B7 V. Description of the invention ()) At a high temperature, for example, at a temperature of about 1000 ° C, a thermal process is performed for about 10 to 30 minutes to densify the silicon oxide filling material 220. (Read the precautions before you read this and then fill out this page) For details, please refer to FIG. 2D to flatten the surface of the substrate 200 comprehensively. Since the mask layer 2 (Ma and the filling material 220 and the lining oxide layer 212 have different honing rates, a better planarization process, With the masking layer 204a as the honing end point, the lining oxide layer 212 and the filling material 220 covered by the surface 218 of the masking layer 204 are removed by honing through a chemical mechanical honing process, leaving the area covered by the recessed area 208. The oxide layer 212a is lined with the filling material 22Qa. The warp section 屮 A <? · B ^^-τ · Consumers can then remove the mask layer 204a by referring to FIG. 2E. A typical method is wet etching. When the material of the mask layer 204a is silicon nitride, a better removal method can be performed with hot phosphoric acid. Since the lining oxide layer 212a and the mask layer 204a have different etching rates, the 'lining oxide layer 212a will not be damaged by etching during the removal of the mask layer 204a, so' after the mask layer 2 (Ma, The lining oxide layer 212a originally covering the side wall 216 of the cover layer 204a can still be retained. Because the side wall 216 of the original cover layer 204a is located above the 214 at the top corner 214 of the trench 206, so the lining oxide layer 212a will protect the top corner 214 of the trench 206 in the subsequent etching process and cleaning process. Finally, please refer to Figure 2F to remove the pad oxide layer 202a. The typical method is to use hydrofluoric acid. The etching solution is a wet etching process to remove the pad oxide layer 202a located above the protruding area 210. Since the oxide layer 212a has a denser structure than the filling material 22a filled in the trench 206, In the process of removing the pad oxide layer 202a with a hydrofluoric acid solution, the etching speed is 9 paper sizes. Chengchuan China National Monument (('NS) A4 gauge cypress (2 丨 0x297 mm) 4l41twf.doc / 008 A7 B7 V. Description of the invention The filling material 220a, therefore, the lining oxide layer 212a located on the side wall 218 of the cover layer 204a, that is, the lining oxide layer 2 12a located at the top corner 214 of the trench 206 can protect the top corner 214 of the trench 206. _Nearly filled material 220a to avoid the phenomenon of depression of the filled material 220a near the top corner 214 of the trench 206 caused by lateral etching. In summary, the feature of the present invention is the wet thermal oxidation method. , The growth process of the lining oxide layer is performed between 950 degrees Celsius and 1180 degrees Celsius. Since the thermal process performed under this condition can not only oxidize the surface of the exposed silicon substrate of the trench, but also oxidize the surface of the mask layer, the lining oxide layer formed not only covers the surface of the trench, but also Cover the extension to the side walls and surface of the mask layer. Therefore, after planarizing the element and removing the mask layer. The lining oxide layer on the side wall of the mask layer will be retained because the etching rate is different from that of the mask layer. Because the lining oxide layer has a higher density than the filling material in the trench, the subsequent etching process of the pad oxide layer with a hydrofluoric acid solution has a lower etching rate than the filling material. The lining oxide layer on the side wall of the curtain layer can protect the filling materials near the top corners of the trench, and avoid the phenomenon that the filling materials near the top corners of the trench are depressed by side etching. 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 modifications and retouches without departing from the spirit and scope of the present invention. Therefore, the present invention The scope of protection v shall be determined by the scope of the attached patent application. The ruler of this paper, Xiao Xun: Choi (rNS) h rule strokes flx297 public dream) (for the precautions on the back of the paper, please fill in this page) ir