用於阻擋層平坦化之化學機械研磨液Chemical mechanical polishing fluid for barrier layer planarization
本發明有關於半導體製造領域，尤指一種可應用於阻擋層平坦化的化學機械研磨液。The present invention relates to the field of semiconductor manufacturing, and in particular, to a chemical mechanical polishing liquid that can be used for planarizing barrier layers.
目前，在積體電路製造中，隨著內連線技術的標準的不斷提高、內連線層數不斷增加、製程特徵尺寸不斷縮小，對矽晶圓表面平整度的要求也越來越高。如果不能實現平坦化，在半導體晶圓上創建複雜和密集的結構就會是非常有限的。 目前，化學機械研磨方法(chemical mechanical polishing，CMP)是可實現整個矽晶圓平坦化的最有效的方法。CMP製程就是使用一種含研磨料的混合物和研磨墊研磨積體電路表面。在典型的化學機械研磨方法中，將基底直接與旋轉研磨墊接觸，用一載重物在基底背面施加壓力。在研磨期間，墊片和操作臺旋轉，同時在基底背面保持向下的力，將研磨料和化學活性溶液(通常稱為研磨液或研磨漿料)塗於墊片上，該研磨液與正在研磨的薄膜發生化學反應開始進行研磨過程。 隨著積體電路技術向超深亞微米(32、28奈米(nanometer，nm))方向發展，因特徵尺寸減小而導致的寄生電容愈加嚴重的影響著電路的性能，為減小這一影響，就必須採用低介電材料來降低相鄰金屬線之間的寄生電容，目前較多採用低介電材料為BD(Black Diamond)，在CMP過程中除了要嚴格控制表面污染物指標以及杜絕金屬腐蝕外，還要具有較低的碟型凹陷和研磨均一性才能保證更加可靠的電性表現，特別是阻擋層的平坦化過程中需要在更短的時間和更低的壓力下快速移除阻擋層金屬和封蓋氧化物，並能很好的停止在低介電材料表面，形成內連線，而且對小尺寸圖形不敏感。這就對CMP提出了更高的挑戰，因為通常低介電材料為摻雜碳的二氧化矽，要控制停止層的殘留厚度，就要有很強的選擇比的調控能力，還要有很高的穩定性和易清洗等特徵。 目前市場上已存在許多應用於阻擋層平坦化的化學機械研磨液，如，CN1400266公開一種鹼性阻擋層研磨液，該研磨液包含二氧化矽磨料、胺類化合物和非離子表面活性劑，其在研磨後，會對銅金屬層產生腐蝕；CN101372089A公開一種鹼性阻擋層研磨液，其含有二氧化矽磨料、腐蝕抑制劑、氧化劑、非離子氟表面活性劑、芳族磺酸氧化劑化合物，其對阻擋層研磨速率較低，研磨效率低；CN101012356A公開一種酸性阻擋層研磨液，其包含氧化劑、部分被鋁覆蓋的二氧化矽顆粒、抑制劑和錯合劑，其對銅金屬層存在嚴重的腐蝕，CN101747843A公開了一種銅化學機械研磨液，其含有研磨顆粒、錯合劑、氧化劑、嵌段聚醚類表面活性劑和水，其中嵌段聚醚的作用是抑制銅的去除速率，未涉及低介電材料的研磨效果。 因此，針對現有技術中存在的問題，尋求一種能夠適合於低介電材料-銅內連線製程中的阻擋層研磨，並可在較溫和的條件下實現高的阻擋層去除速率和低介電材料介面的製程停止特性，同時能很好的控制碟型凹陷、金屬腐蝕和表面污染物的化學機械研磨液是本行業亟待解決的問題。Currently, in integrated circuit manufacturing, as the standards of interconnection technology continue to improve, the number of interconnection layers continues to increase, and the feature size of the process continues to shrink, the requirements for the surface flatness of silicon wafers are also getting higher and higher. Without planarization, creating complex and dense structures on semiconductor wafers is very limited. Currently, chemical mechanical polishing (CMP) is the most effective method to achieve planarization of the entire silicon wafer. The CMP process uses an abrasive mixture and a polishing pad to polish the surface of the integrated circuit. In a typical chemical mechanical polishing method, the substrate is placed in direct contact with a rotating polishing pad and a load is used to apply pressure on the backside of the substrate. During grinding, the pad and table rotate while maintaining a downward force on the back of the substrate, applying the abrasive and chemically active solution (often called abrasive fluid or slurry) to the pad. A chemical reaction occurs in the ground film to begin the grinding process. As integrated circuit technology develops towards ultra-deep sub-micron (32 and 28 nanometer (nm)), the parasitic capacitance caused by the reduction in feature size has increasingly seriously affected the performance of the circuit. In order to reduce this Therefore, low dielectric materials must be used to reduce the parasitic capacitance between adjacent metal lines. Currently, low dielectric materials are mostly used as BD (Black Diamond). In the CMP process, in addition to strictly controlling surface pollutant indicators and eliminating In addition to metal corrosion, lower dishing and grinding uniformity are required to ensure more reliable electrical performance, especially during the planarization process of the barrier layer, which needs to be quickly removed in a shorter time and lower pressure. The barrier metal and capping oxide can stop well on the surface of low-dielectric materials to form interconnects, and are not sensitive to small-size patterns. This poses a higher challenge to CMP, because usually the low-dielectric material is carbon-doped silicon dioxide. To control the residual thickness of the stop layer, it is necessary to have a strong selectivity control ability and a lot of High stability and easy cleaning. Currently, there are many chemical mechanical polishing slurries used for barrier layer planarization on the market. For example, CN1400266 discloses an alkaline barrier layer polishing slurry, which contains silica abrasives, amine compounds and nonionic surfactants. After grinding, the copper metal layer will be corroded; CN101372089A discloses an alkaline barrier layer grinding fluid, which contains silica abrasives, corrosion inhibitors, oxidants, nonionic fluorine surfactants, and aromatic sulfonic acid oxidant compounds. The polishing rate for the barrier layer is low and the polishing efficiency is low; CN101012356A discloses an acidic barrier layer polishing fluid, which contains oxidants, silicon dioxide particles partially covered with aluminum, inhibitors and complexing agents, which has severe corrosion on the copper metal layer. , CN101747843A discloses a copper chemical mechanical polishing liquid, which contains grinding particles, complexing agents, oxidants, block polyether surfactants and water, in which the function of the block polyether is to inhibit the removal rate of copper, and does not involve low media Grinding effect of electrical materials. Therefore, in view of the problems existing in the prior art, a method is sought that is suitable for barrier layer polishing in the low-dielectric material-copper interconnection process, and can achieve high barrier layer removal rate and low dielectric under mild conditions. The process stop characteristics of the material interface and the chemical mechanical polishing fluid that can well control dishing, metal corrosion and surface contaminants are issues that need to be solved urgently in this industry.
為解決上述問題，本發明提供一種阻擋層化學機械研磨液，其在較溫和的條件下，對阻擋層材料與介電層材料具有高移除率，對低介電材料與銅則具有可變的移除率；在研磨過程中對碟型凹陷、介電層與金屬侵蝕的產生具有很好的控制，且在研磨時可減少晶圓表面污染。 具體地，本發明提供了一種用於阻擋層平坦化的化學機械研磨液，其包含研磨顆粒、唑類化合物、錯合劑、非離子表面活性劑和氧化劑，其中，該非離子表面活性劑為嵌段聚醚類化合物。 其中，該研磨顆粒為二氧化矽顆粒；研磨顆粒的重量百分比濃度較佳為2~20%，更佳為5~15%；該的研磨顆粒的粒徑較佳為10~250nm，更佳為50~200nm。 其中，該唑類化合物，較佳選自下列中的一種或多種：苯並三氮唑、甲基苯並三氮唑、5-苯基四氮唑、5-氨基-四氮唑、巰基苯基四氮唑、苯並咪唑，萘並三唑和2-巰基-苯並噻唑。該唑類化合物的重量百分比濃度較佳為0.001~1%，更佳為0.01~0.5%。 其中，該錯合劑係選自有機羧酸、有機膦酸、氨基酸和有機胺中的一種或多種，較佳的選自下列中的一種或多種：乙酸、丙酸、草酸、丙二酸、丁二酸、檸檬酸、乙二胺四乙酸、2-膦酸丁烷-1，2，4-三羧酸、氨基三甲叉膦酸、羥基乙叉二膦酸、乙二胺四甲叉膦酸、甘氨酸和乙二胺，該錯合劑的重量百分比濃度較佳為0.001~2%，更佳為0.01~1%。 其中，該嵌段聚醚類化合物為聚氧乙烯-聚氧丙烯-聚氧乙烯三嵌段聚醚。該嵌段聚醚類化合物具有以下化學式：(CH2
CH2
O)x-(CH(CH3
)CH2
O)y-(CH2
CH2
O)z-OH，也可表示為(EO)x-(PO)y-(EO)z其中，10≤x,y,z≤150。該嵌段聚醚類表面活性劑的重量百分比濃度較佳為0.001~1.0%，更佳為0.01~0.5%。 其中，氧化劑係選自下列中的一種或多種：過氧化氫、過氧乙酸、過硫酸鉀和過硫酸銨，較佳為過氧化氫。該氧化劑的重量百分比濃度較佳為0.01~5%，更佳為0.1~2%。 其中，該化學機械研磨液的pH值為8.0~12.0，更佳為9.0~11.0。 另外，本發明的化學機械研磨液還可以包含pH調節劑和殺菌劑等其他本領域添加劑。 且，本發明的化學機械研磨液可以濃縮製備，使用時用去離子水稀釋並添加氧化劑至本發明的濃度範圍使用。 與現有技術相比較，本發明的技術優勢在於：其在較溫和的條件下，對阻擋層材料與介電層材料具有高移除率，對低介電材料與銅則具有可變的移除率；在研磨過程中對碟型凹陷、介電層與金屬侵蝕的產生具有很好的控制，且在研磨時可減少晶圓表面污染。且可濃縮製備，方便儲存以及運輸和使用。In order to solve the above problems, the present invention provides a barrier layer chemical mechanical polishing liquid, which has a high removal rate for barrier layer materials and dielectric layer materials under relatively mild conditions, and has a variable removal rate for low dielectric materials and copper. The removal rate is very good; it has good control over the occurrence of dish-shaped depressions, dielectric layers and metal erosion during the grinding process, and can reduce wafer surface contamination during grinding. Specifically, the present invention provides a chemical mechanical polishing liquid for barrier layer planarization, which contains abrasive particles, azole compounds, complexing agents, nonionic surfactants and oxidants, wherein the nonionic surfactants are blocks. Polyether compounds. Wherein, the abrasive particles are silica particles; the weight percentage concentration of the abrasive particles is preferably 2~20%, more preferably 5~15%; the particle size of the abrasive particles is preferably 10~250nm, more preferably 50~200nm. Among them, the azole compound is preferably selected from one or more of the following: benzotriazole, methylbenzotriazole, 5-phenyltetrazole, 5-amino-tetrazole, mercaptobenzene tetrazole, benzimidazole, naphthotriazole and 2-mercapto-benzothiazole. The weight percentage concentration of the azole compound is preferably 0.001~1%, more preferably 0.01~0.5%. Wherein, the complexing agent is selected from one or more of organic carboxylic acids, organic phosphonic acids, amino acids and organic amines, preferably one or more of the following: acetic acid, propionic acid, oxalic acid, malonic acid, butyric acid Diacid, citric acid, ethylenediaminetetraacetic acid, 2-phosphonic acid butane-1,2,4-tricarboxylic acid, aminotrimethylenephosphonic acid, hydroxyethylidenediphosphonic acid, ethylenediaminetetramethylenephosphonic acid , glycine and ethylenediamine, the weight percentage concentration of the complex agent is preferably 0.001~2%, more preferably 0.01~1%. Wherein, the block polyether compound is a polyoxyethylene-polyoxypropylene-polyoxyethylene triblock polyether. The block polyether compound has the following chemical formula: (CH 2 CH 2 O)x-(CH(CH 3 )CH 2 O)y-(CH 2 CH 2 O)z-OH, which can also be expressed as (EO) x-(PO)y-(EO)z where, 10≤x,y,z≤150. The weight percentage concentration of the block polyether surfactant is preferably 0.001~1.0%, more preferably 0.01~0.5%. Wherein, the oxidizing agent is selected from one or more of the following: hydrogen peroxide, peracetic acid, potassium persulfate and ammonium persulfate, preferably hydrogen peroxide. The weight percentage concentration of the oxidant is preferably 0.01~5%, more preferably 0.1~2%. Among them, the pH value of the chemical mechanical polishing liquid is 8.0~12.0, and more preferably is 9.0~11.0. In addition, the chemical mechanical polishing liquid of the present invention may also contain other additives in the field such as pH adjusters and bactericides. Moreover, the chemical mechanical polishing liquid of the present invention can be prepared by concentration. When used, it is diluted with deionized water and an oxidizing agent is added to the concentration range of the present invention. Compared with the existing technology, the technical advantage of the present invention is that it has a high removal rate for barrier layer materials and dielectric layer materials under milder conditions, and has variable removal rates for low dielectric materials and copper. efficiency; it has good control over the occurrence of dish-shaped depressions, dielectric layer and metal erosion during the grinding process, and can reduce wafer surface contamination during grinding. It can be concentrated and prepared for easy storage, transportation and use.
以下係藉由實施例的方式進一步說明本發明，但並不以此將本發明限制在該的實施例範圍之中。 表1係提供對照組研磨液1~2和本發明的研磨液1~13，按表中所給的配方，係將除了氧化劑以外的其他組分混合均勻，用氫氧化鉀(KOH)或硝酸(HNO3
)調節到所需要的pH值。使用前加氧化劑，混合均勻即可。水為餘量。 表1 對照組研磨液1~2和本發明研磨液1~13
效果實施例1 採用對照組研磨液1~2和本發明研磨液1~9按照下述條件對銅(Cu)、阻擋層材料鉭(Ta)、介電材料二氧化矽(TEOS)和低介電材料(BD)進行研磨。研磨條件：研磨機台為12” Reflexion LK 機台，研磨墊為Fujibo pad，下壓力為1.5psi，轉速為研磨盤/研磨頭=113/107rpm，研磨液流速為300ml/min，研磨時間為1分鐘(min)。 表2 對照組研磨液1~2和本發明研磨液1~9對銅(Cu)、鉭(Ta)、 二氧化矽(TEOS)和低介電材料(BD)的移除率
由表2可見，與對照組研磨液1與2相比，本發明的研磨液可以獲得較高的阻擋層材料Ta和介電材料二氧化矽(TEOS)的移除率，可以縮短研磨時間，提高產能，同時通過添加不同量的嵌段聚醚類化合物表面活性劑，將低介電材料BD的移除率控制在比TEOS低，有利於控制圖案化晶圓的研磨過程和研磨後的BD剩餘厚度，並保證晶圓的表面均一性。 效果實施例2 採用對照組研磨液2和本發明的研磨液1~3按照下述條件對包含有圖案的銅晶圓進行研磨。該圖案化晶圓為市售的12英寸Sematech754圖案化晶圓，膜層材料從上至下為銅/鉭/氮化鉭/TEOS/BD，研磨過程分三步，第一步用市售的銅研磨液去除大部分的銅，第二步用市售的銅研磨液去除殘留的銅，第三步用本發明的阻擋層研磨液將阻擋層(鉭/氮化鉭)、二氧化矽TEOS、和部分低介電材料BD去除並停在BD層上。阻擋層研磨液研磨條件：研磨機台為12”Reflexion LK機台，研磨墊為Fujibo pad，下壓力為1.5psi，轉速為研磨盤/研磨頭=113/107rpm，研磨液流速為300ml/min，研磨時間為70秒(s)。 表3 對照組研磨液2和本發明研磨液1~3對帶有圖案的銅晶圓研磨後的矯正能力對比
其中，上文中所述之碟形凹陷(Dishing)，是指阻擋層研磨前在金屬墊上的碟型凹陷，侵蝕(Erosion)是指阻擋層線上寬為0.18微米(micrometer，μm)，密度為50%的密線區域(50%銅/50%介電層)上的介質層侵蝕，∆(埃)是指研磨後的矯正能力值。 由表3可以看出，與對照組研磨液2相比，本發明的研磨液由於抑制了低介電材料BD的移除率，能很好地停止在BD上，有效的控制了圖案化晶圓的研磨過程和保證了研磨後的BD剩餘厚度，能較好的修正前程(銅研磨後)在晶圓上產生的碟型凹陷和侵蝕，獲得了較好的晶圓形貌。 效果實施例3 採用對照組研磨液1和研磨液1按照下述條件對帶有圖案的銅晶圓進行研磨。該圖案化晶圓為市售的12英寸Sematech754圖案化晶圓，膜層材料從上至下為銅/鉭/氮化鉭/TEOS/BD，研磨過程分三步，第一步用市售的銅研磨液去除大部分的銅，第二步用市售的銅研磨液去除殘留的銅，第三步用本發明的阻擋層研磨液將阻擋層(鉭/氮化鉭)、二氧化矽TEOS、和部分低介電材料BD去除並停在BD層上。 圖1和圖2分別為採用對照組研磨液1和本發明研磨液1研磨後，Sematech 754圖案化測試晶圓的表面形貌的掃描式電子顯微鏡照片。對照組可以看出，本發明的研磨液有效的抑制了金屬腐蝕，特別是對銅線區域有很好的保護，圖案化測試晶圓經過本發明的研磨液研磨後，表面仍然清晰銳利，未發現金屬腐蝕現象，且無污染顆粒殘留。 應當注意的是，本發明的實施例有較佳的實施性，且並非對本發明作任何形式的限制，任何熟悉該領域的技術人員可能利用上述揭示的技術內容變更或修飾為等同的有效實施例，但凡未脫離本發明技術方案的內容，依據本發明的技術實質對以上實施例所作的任何修改或等同變化及修飾，均仍屬於本發明技術方案的範圍內。 上述內容概述了若干實施例之特徵以使得熟習此項技術者可更好理解本揭示之各態樣。熟習此項技術者應瞭解，其可易於將本揭示用作設計或修改用於進行與本文中介紹之實施例相同的目的及/或實現與其相同的優勢之其他程序及結構之基礎。熟習此項技術者亦應認識到，此類等效結構並不脫離本揭示之精神及範疇，並且在不脫離本揭示之精神及範疇的情況下可在此處進行各種改變、替代及更改。The present invention is further described below by means of examples, but the present invention is not limited to the scope of the examples. Table 1 provides the grinding liquids 1 to 2 of the control group and the grinding liquids 1 to 13 of the present invention. According to the formula given in the table, other components except the oxidant are mixed evenly, and potassium hydroxide (KOH) or nitric acid is used. (HNO 3 ) adjusted to the desired pH value. Add oxidant before use and mix evenly. Water is the balance. Table 1 Grinding liquids 1 to 2 of the control group and grinding liquids 1 to 13 of the present invention Effect Example 1 Using the control polishing slurry 1 to 2 and the polishing slurry 1 to 9 of the present invention according to the following conditions, copper (Cu), barrier layer material tantalum (Ta), dielectric material silicon dioxide (TEOS) and low dielectric The electrical material (BD) is ground. Grinding conditions: The grinding machine table is a 12” Reflexion LK machine table, the grinding pad is a Fujibo pad, the down pressure is 1.5psi, the rotation speed is grinding disc/grinding head = 113/107rpm, the grinding fluid flow rate is 300ml/min, and the grinding time is 1 Minutes (min). Table 2 Removal of copper (Cu), tantalum (Ta), silicon dioxide (TEOS) and low dielectric material (BD) by the control polishing liquids 1 to 2 and the present invention polishing liquids 1 to 9 Rate As can be seen from Table 2, compared with the control polishing liquids 1 and 2, the polishing liquid of the present invention can obtain a higher removal rate of the barrier material Ta and the dielectric material silicon dioxide (TEOS), and can shorten the polishing time. Increase production capacity, and at the same time, by adding different amounts of block polyether compound surfactants, the removal rate of low dielectric material BD is controlled to be lower than that of TEOS, which is beneficial to controlling the grinding process of patterned wafers and the BD after grinding remaining thickness and ensure surface uniformity of the wafer. Effect Example 2 A copper wafer containing a pattern was polished using the control polishing liquid 2 and the polishing liquids 1 to 3 of the present invention according to the following conditions. The patterned wafer is a commercially available 12-inch Sematech754 patterned wafer. The film layer materials from top to bottom are copper/tantalum/tantalum nitride/TEOS/BD. The grinding process is divided into three steps. The first step is to use commercially available The copper polishing liquid removes most of the copper. In the second step, a commercially available copper polishing liquid is used to remove the remaining copper. In the third step, the barrier layer polishing liquid of the present invention is used to remove the barrier layer (tantalum/tantalum nitride) and silicon dioxide TEOS. , and part of the low dielectric material BD is removed and stops on the BD layer. Barrier layer grinding fluid grinding conditions: The grinding machine table is a 12" Reflexion LK machine table, the grinding pad is a Fujibo pad, the down pressure is 1.5psi, the rotation speed is the grinding disc/grinding head = 113/107rpm, the grinding fluid flow rate is 300ml/min, The grinding time is 70 seconds (s). Table 3 Comparison of the correction capabilities of the polishing liquid 2 of the control group and the grinding liquid 1~3 of the present invention after grinding the patterned copper wafers Among them, the dishing mentioned above refers to the dishing on the metal pad before the barrier layer is polished, and the erosion refers to the line width of the barrier layer being 0.18 micrometer (micrometer, μm) and the density being 50 % dielectric layer erosion on the dense line area (50% copper/50% dielectric layer), Δ (angstrom) refers to the correction ability value after grinding. As can be seen from Table 3, compared with the control group polishing liquid 2, the polishing liquid of the present invention suppresses the removal rate of the low dielectric material BD, can stop on the BD well, and effectively controls the patterned crystal structure. The round grinding process ensures the remaining thickness of the BD after grinding, which can better correct the dish-shaped depression and erosion caused on the wafer in the previous process (after copper grinding), and obtain a better wafer appearance. Effect Example 3 A patterned copper wafer was polished using the control polishing liquid 1 and the polishing liquid 1 according to the following conditions. The patterned wafer is a commercially available 12-inch Sematech754 patterned wafer. The film layer materials from top to bottom are copper/tantalum/tantalum nitride/TEOS/BD. The grinding process is divided into three steps. The first step is to use commercially available The copper polishing liquid removes most of the copper. In the second step, a commercially available copper polishing liquid is used to remove the remaining copper. In the third step, the barrier layer polishing liquid of the present invention is used to remove the barrier layer (tantalum/tantalum nitride) and silicon dioxide TEOS. , and part of the low dielectric material BD is removed and stops on the BD layer. Figures 1 and 2 are scanning electron microscope photos of the surface morphology of the Sematech 754 patterned test wafer after polishing with the control polishing liquid 1 and the inventive polishing liquid 1 respectively. It can be seen from the control group that the polishing slurry of the present invention effectively inhibits metal corrosion, especially the copper wire area. After being polished by the polishing slurry of the present invention, the surface of the patterned test wafer is still clear and sharp. Metal corrosion was found and no contaminant particles remained. It should be noted that the embodiments of the present invention have better implementability and are not intended to limit the present invention in any way. Any person familiar with the art may change or modify the above-disclosed technical contents into equivalent and effective embodiments. , as long as they do not deviate from the content of the technical solution of the present invention, any modifications or equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention still fall within the scope of the technical solution of the present invention. The above summary summarizes the features of several embodiments to enable those skilled in the art to better understand various aspects of the present disclosure. Those skilled in the art should appreciate that they may readily use the present disclosure as a basis for designing or modifying other procedures and structures for carrying out the same purposes and/or achieving the same advantages of the embodiments introduced herein. Those skilled in the art should also realize that such equivalent structures do not depart from the spirit and scope of the present disclosure, and that various changes, substitutions and alterations may be made herein without departing from the spirit and scope of the present disclosure.
圖1和圖2分別為採用對照組研磨液1和本發明研磨液1研磨後，Sematech 754圖案化測試晶圓的表面形貌的掃描式電子顯微鏡照片。Figures 1 and 2 are scanning electron microscope photos of the surface morphology of the Sematech 754 patterned test wafer after polishing with the control polishing liquid 1 and the inventive polishing liquid 1 respectively.
