A7 五、發明説明（ 發明領域： 本發明與一種半導體製程有關，特别是一種半導體製 程之保護層形成方法。 發明背景： ------- ' _ | 丨·丨 隨著超大型積體電路技術的實用化，半導體元件如記 憶單元等的尺寸皆大幅縮小，以配合日益縮減的積體電路 面積P爲了達到更高的晶片密度，動態隨機存取記憶體 (dynamic random access mem〇ries; dram)的單元尺寸 已縮減至次微米的範園，而半導體元件的尺寸將會持續的 下降6 積體電路的主要製程包括形成半導體元件、隔離結 構、内連線以及傷護層等的方法。保護層一般最常見的作 用，是用來保護其下的各半導體層，防止濕氣入侵造成元 件的失效。一般皆以氧化矽/氡化矽的組合形成保護層， 傳統上是用電漿強化的化學氣相沈積法（PECVD)來沈積 氧化矽/氮化矽層。 半導體元件尺寸的縮減，進一步造成了形成保護層製 程上的問題。因爲隨著尺寸的縮減，金屬連線間的距離亦 大幅減少，而金屬連線間距離的減小，使得形成保護層製 程複雜化，並造成保護層失效的問題。 圖一及圖二顯示一半導體底材2 ，其上有〜隔離層 2 經濟部中央標準局員工消費合作社印製 五、發明説明（） 4,金屬層6及氧化矽/氮化矽層8依序形成於其上。氧化 矽/氮化矽層8即爲保護層。金屬層6中的金屬連線彼此 間距的減小使得氧化矽/氮化矽層8在沈積時產生孔隙 10 ?在後續製程光阻塗布及剥除的過程中，孔隙内光 阻的積存及揮發會造成銲墊的腐蝕，而降低元件的可靠 度。 傳統以PECVD沈積的氧化矽/氮化矽層的另一缺點 是較差的階梯覆蓋性’造成在針礼測試時的失效。可參閲 圖二。 因此，目前迫切需要一種新的保護層形成方法，來避 免傳統保護層製程所產生的上速缺點，以進一步提高半導 體生產之良率及元件的可靠度6 3A7 V. Description of the invention (Field of the invention: The present invention relates to a semiconductor process, in particular to a method for forming a protective layer of a semiconductor process. Background of the invention: ------- '_ | As circuit technology becomes practical, the size of semiconductor components such as memory cells has been significantly reduced to match the ever-decreasing integrated circuit area P. In order to achieve higher chip densities, dynamic random access memory (dynamic random access memory); The cell size of dram has been reduced to the sub-micron range, and the size of semiconductor devices will continue to decrease. 6 The main processes of integrated circuits include methods of forming semiconductor devices, isolation structures, interconnects, and protective layers. The most common role of the protective layer is to protect the semiconductor layers underneath to prevent the failure of the component caused by moisture intrusion. Generally, the protective layer is formed by a combination of silicon oxide / silicon oxide, which is traditionally strengthened with a plasma. Chemical Vapor Deposition (PECVD) to deposit silicon oxide / silicon nitride layers. The reduction in the size of semiconductor components has further led to the formation of a protective layer process. The problem is that with the reduction in size, the distance between the metal lines is also greatly reduced, and the decrease in the distance between the metal lines complicates the process of forming the protective layer and causes the problem of the protective layer failure. Figure 1 and Figure 2 shows a semiconductor substrate 2 with ~ isolation layer 2 printed on it by the Consumer Cooperative of the Central Standards Bureau of the Ministry of Economic Affairs. 5. Description of the invention () 4, metal layer 6 and silicon oxide / silicon nitride layer 8 are sequentially formed on Above it, the silicon oxide / silicon nitride layer 8 is a protective layer. The reduction in the distance between the metal wires in the metal layer 6 causes the silicon oxide / silicon nitride layer 8 to generate pores 10 during deposition. Photoresist in subsequent processes During the coating and stripping process, the accumulation and volatilization of photoresist in the pores will cause the pads to corrode and reduce the reliability of the device. Another disadvantage of the traditional silicon oxide / silicon nitride layer deposited by PECVD is the poor step Coverage 'causes failure during the needle test. See Figure 2. Therefore, a new protective layer formation method is urgently needed to avoid the high-speed disadvantages caused by the traditional protective layer process in order to further improve the semiconductor Production yield and reliability of the element 63
士 π p亦；杰田士撕固定後电f rNS ) A4规格（210X 297公瘦) A7 ___一 ___ B7 五、發明説明（） I明目的及概述：_ 本發明的目的爲提供一種半導體製程之保護層形成 方珐。 本發呵的另一目的爲提供一種具有轉佳階梯覆蓋 性，及避免金屬内連線間孔隙的半導體製程之保護層形成 方法。 本發明首先形成一隔離層於半導體底材上，接著形成 一金屬層，作爲内連線層。典金屬層可以是如鋁、銅、 經濟部中央標準局員工消費合作社印製 鱗、欽等的導體材質。接著，以臭氧及矽有機化合物 (Tetn-Ethyl-Ortho-SiHcate ; TEOS)作爲反應氣體，在 溫度约爲380至420 eC下，以次大氣壓化學氣相沈積法 (^ub atmospheric chemical vapor deposition ； SACVD) 耜成一未摻雜之矽化玻璃（undoped silicate glass; USG) 層。其中以氧氣做爲臭氧的戴氣，氧氣的氣體流量約爲 4000至6000 seem。以氫氣作爲TEOS的載氣，該氫氣的 氣體流量约爲3000至5000 seem。TEOS的氣體流率约爲 350至450mg/min，，以一較佳實施例而言，其値約爲 320mg/min·。然後使用電漿強化的化學氣相沈積法 (plasma enhanced chemical vapor deposition ; PECVD)，形成一氮化矽層做爲主要的保護層，厚度约爲 3000埃至7000埃。形成氮化矽層的製程溫度約爲4〇〇 ec A7 五、發明説明（） 至800 ·〇。形成氮化矽層製程的反應氣體可爲SiH4、 NH3、N2、N20 的組合或是 SiH2Cl2、NH3、n2、n2o 的組合。 此外，在形成一未摻雜之矽化玻璃（USG)層之前，可 沈積一層較薄的氧化矽或氮氧化矽於金凑層上做爲墊 層。此一墊層可在金屬層與其他層間，做爲減低應力及熱 載子的緩衝區。 圖式簡軍説明： 第一圖爲傳統製程，在高密度金屬内連線間形成保護層内 孔隙之截高圏； 第二圖爲傳統保護層製程，在相鄰金屬連線間，其階梯覆 蓋情形不佳乏截面學； 第二圖爲本發明在高密度金屬内連線層上，形成勢層之 截面圏； 第四圖爲本發明在墊層上，形成一未摻雜的矽化玻璃 (USG)層之截面圖； 第五圖爲本發明在未摻雜的矽化玻璃（USG)層上，形成一 氮化矽層之截面圖；及 經濟部中央標準局員工消費合作社印製 第六圖爲本發明在在相鄰金屬連線間，提供良好階梯覆蓋 性之截面圖。 發明詳細説日q ： 本紙張尺度適用中國國家標準（CNS ) A4規格（210X297公釐Shi π p; Jie Tianshi tear and fix electric f rNS) A4 specifications (210X 297 male thin) A7 ___ 一 ___ B7 V. Description of the invention () I Purpose and summary: _ The purpose of the present invention is to provide a The protective layer of the semiconductor process forms a square enamel. Another object of the present invention is to provide a method for forming a protective layer in a semiconductor process having improved step coverage and avoiding pores between metal interconnects. The present invention first forms an isolation layer on a semiconductor substrate, and then forms a metal layer as an interconnect layer. The typical metal layer can be made of conductor materials such as aluminum, copper, and scales printed by the Consumer Cooperatives of the Central Standards Bureau of the Ministry of Economic Affairs. Next, using ozone and silicon organic compounds (Tetn-Ethyl-Ortho-SiHcate; TEOS) as reaction gases at a temperature of about 380 to 420 eC, ^ ub atmospheric chemical vapor deposition (SACVD) ) Is formed into an undoped silicate glass (USG) layer. Among them, oxygen is used as ozone gas, and the gas flow rate of oxygen is about 4000 to 6000 seem. Using hydrogen as a carrier gas for TEOS, the gas flow rate of the hydrogen is about 3000 to 5000 seem. The gas flow rate of TEOS is about 350 to 450 mg / min, and in a preferred embodiment, it is about 320 mg / min. Then a plasma enhanced chemical vapor deposition (PECVD) method is used to form a silicon nitride layer as a main protective layer, with a thickness of about 3000 angstroms to 7000 angstroms. The process temperature for forming the silicon nitride layer is about 400 ec A7. V. Description of the invention () to 800 ° C. The reaction gas used in the process of forming the silicon nitride layer may be a combination of SiH4, NH3, N2, and N20, or a combination of SiH2Cl2, NH3, n2, and n2o. In addition, before forming an undoped siliconized glass (USG) layer, a thinner layer of silicon oxide or silicon oxynitride can be deposited on the gold layer as a cushion layer. This cushion layer can be used as a buffer to reduce stress and hot carriers between the metal layer and other layers. Brief description of the drawings: The first picture is the traditional process, which forms the cut-off height of the pores in the protective layer between the high-density metal interconnects. The second picture is the traditional protective layer process. The coverage is poor and lacks cross-section. The second picture shows the cross-section of the potential layer formed on the high-density metal interconnect layer according to the present invention. The fourth picture shows the formation of an undoped siliconized glass on the pad layer according to the present invention (USG) layer cross-section; the fifth figure is a cross-sectional view of the present invention forming a silicon nitride layer on an undoped siliconized glass (USG) layer; and the sixth printed by the Consumer Cooperative of the Central Standards Bureau of the Ministry of Economic Affairs The figure is a cross-sectional view of the present invention that provides good step coverage between adjacent metal lines. Detailed description of the invention day q: This paper size applies to China National Standard (CNS) A4 specification (210X297 mm)
五、發明説明（ 本發明揭示一種半導體製程之保 :護層的效果，並具有良好的階梯覆蓋性V詳細説= 龜久主道骑-从 層22 ’用以隔 主要精神及實施之關鍵與方法，當是本文做細節描= 論之重點。 = 所包含之基本製程技術，爲熟悉半 經濟部中央標準局員工消費合作社印製 接著，在隔離層22形成後，於其上形成—做爲金屬 内連線層的金屬層24。此金羼層可以是如鋁、銅、鎢、 鈦等具相似特性的導體材質。傳統的微影及蝕刻製程可用 來形成其連線圖案。 然後再沈積一層較薄的氧化矽或氮氧化矽墊層26， 沿著金屬層圖案邊緣以PECVD方式沈積。該墊層26的厚 度小於約1000埃。此一薄墊層的作用在於金屬層24與其 他層間，形成一做爲減低應力及熱载子的缓衝區。因此沈 積此一薄墊層的步驟並非必要條件，可視需要而決定。 參閲第四圖，在薄墊層26上方形成一未摻雜之矽化 玻璃（USG)層28。此USG層28的厚度约爲1000埃至6000 埃。以一較佳的實施例而言，此USG層28是以次大氣壓 化學氣相沈積法（SACVD)，在溫度約爲380至420 1〇下， 以臭氧及TEOS作爲反應氣體沈積所得。常壓化學氣相沈 本紙張尺度適用中國國家標準（CNS ) Α4規格（21〇><297公釐）V. Description of the invention (The present invention discloses the protection of a semiconductor process: the effect of a protective layer and good step coverage. In detail = Guijiu Road Ride-Slave layer 22 'is used to isolate the main spirit and the key to implementation The method, when it is described in detail in this article = the focal point of the discussion. = The basic process technology included is printed for the staff consumer cooperatives who are familiar with the Central Bureau of Standards of the Ministry of Semi-Economy. The metal layer 24 of the metal interconnect layer. The Au layer can be a conductor material with similar characteristics such as aluminum, copper, tungsten, titanium, etc. Traditional lithography and etching processes can be used to form its interconnect pattern. Then it is deposited A thinner layer of silicon oxide or silicon oxynitride is deposited by PECVD along the edge of the metal layer pattern. The thickness of the cushion layer 26 is less than about 1000 angstroms. The function of this thin cushion layer is between the metal layer 24 and other layers To form a buffer area for reducing stress and hot carriers. Therefore, the step of depositing this thin cushion layer is not necessary and can be determined as needed. Referring to the fourth figure, an undoped layer is formed on the thin cushion layer 26. Hybrid Silicated Glass (USG) layer 28. The thickness of this USG layer 28 is about 1000 Angstroms to 6000 Angstroms. In a preferred embodiment, this USG layer 28 is a sub-atmospheric chemical vapor deposition (SACVD) method. At a temperature of about 380 to 420 10, it is obtained by depositing ozone and TEOS as reactive gases. Atmospheric pressure chemical vapor deposition of this paper applies the Chinese National Standard (CNS) A4 specification (21〇 > < 297 mm). )
經濟部中央標準局員工消費合作社印製 五、發明説明（） 積法（APCVD)亦可以用來沈積此USG層28。其中以氧氣 做爲臭氧的載氣，氧氣的氣體流量约爲4000至6000 seem。以氫氣作爲TEOS的載氣，氦氣的氣體流量約爲 3000至5000 seem 。 TEOS的氣體流率约爲250至 350mg/min，其一較佳實施値約爲320mg/min,〇以臭氧 及TEOS反應而得的矽化玻璃（USG)層，因其流勢性較佳 而具有良好的缝隙填補能力。 參閲第五圖，在USG層28上方使用電漿強化的化學 氣相沈積法（PECVD)形成一氮化矽層30。此氮化矽層30 爲主要的保護層，其厚度約爲3000埃至7000埃θ形成氮 化矽層30的製程溫度约爲350 eC至450 °C。以一較佳的 實施例而言，形成氮化矽層30製程的反應氣體可爲 SiH4、NH3、N2、N2〇的組合或是 SiH2Cl2、NH3、 N2、N2O的組合。 本發明的保護層形成方法，相較於習知技藝，有許多 重要的優點。一例爲氮化矽層30可以防止溼氣及鹼金屬 離子如鈉、鉀等離子的穿透。另一例爲本發明中未摻雜之 矽化玻璃（USG)層28克服了傳統以PECVD方法形成氮化 矽層階梯覆蓋性不佳的缺點。再以另一例言，本發明的保 護層形成方法可有效解決目前已知故藝在側壁處強度較 弱的問題，推測其原因應爲針孔所造成。實驗的結果顯示 本發明中的USG層28及氮化矽層30可順利的通過針孔測 圖六顯示運用本發明的方法，將USG層28及氮化矽 本紙張尺度適用中國國家標準（CNS ) A4規格（210X297公釐） 五、發明説明（） ^ 層30形成於底材20、金屬層24、及隔離層26之上。可 顯示本發明的方法提供一絶佳的階梯覆蓋能力。 本發明以一較佳實施例説明如上，而熟悉此領域技藝 者，在不膦離本發明之精神範圍内，當可作些許更動潤 飾，其專利保護範園更當視後附之申請專利範園及其等同 領域而定。 經濟部中央標準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（210X 297公釐）Printed by the Consumers' Cooperative of the Central Standards Bureau of the Ministry of Economic Affairs 5. Description of Invention (APCVD) can also be used to deposit this USG layer28. Among them, oxygen is used as a carrier gas for ozone, and the gas flow rate of oxygen is about 4000 to 6000 seem. With hydrogen as the carrier gas for TEOS, the gas flow of helium is about 3000 to 5000 seem. The gas flow rate of TEOS is about 250 to 350 mg / min. One preferred implementation is about 320 mg / min. The siliconized glass (USG) layer obtained by the reaction of ozone and TEOS has a better flow potential and has Good gap filling ability. Referring to the fifth figure, a silicon nitride layer 30 is formed over the USG layer 28 using a plasma enhanced chemical vapor deposition (PECVD) method. The silicon nitride layer 30 is a main protective layer. The thickness of the silicon nitride layer 30 is about 3000 angstroms to 7000 angstroms. The process temperature of forming the silicon nitride layer 30 is about 350 eC to 450 ° C. In a preferred embodiment, the reaction gas used in the process of forming the silicon nitride layer 30 may be a combination of SiH4, NH3, N2, N2O, or a combination of SiH2Cl2, NH3, N2, N2O. The protective layer forming method of the present invention has many important advantages compared with the conventional technique. One example is that the silicon nitride layer 30 prevents penetration of moisture and alkali metal ions such as sodium and potassium. Another example is the undoped siliconized glass (USG) layer 28 in the present invention, which overcomes the disadvantage of poor step coverage of the conventional silicon nitride layer formed by PECVD. To take another example, the protective layer forming method of the present invention can effectively solve the problem of weak strength at the side wall of the known conventional art, and the reason is presumably due to pinholes. The results of the experiment show that the USG layer 28 and the silicon nitride layer 30 in the present invention can pass through the pinhole. Figure 6 shows that the USG layer 28 and the silicon nitride paper are applied to the Chinese national standard (CNS) using the method of the present invention. ) A4 specification (210X297 mm) 5. Description of the invention () ^ The layer 30 is formed on the substrate 20, the metal layer 24, and the isolation layer 26. It can be shown that the method of the present invention provides an excellent step coverage capability. The present invention has been described above with a preferred embodiment, and those skilled in the art can make some modifications to the scope of the invention without departing from the spirit of the present invention. Park and its equivalent. Printed by the Consumer Cooperatives of the Central Bureau of Standards of the Ministry of Economic Affairs 8 This paper is sized to the Chinese National Standard (CNS) A4 (210X 297 mm)