一種用於阻擋層平坦化的化學機械拋光液Chemical mechanical polishing liquid for flattening barrier layer
本發明涉及一種化學機械拋光液，尤其涉及一種用於阻擋層平坦化的化學機械拋光液及其使用方法。The present invention relates to a chemical mechanical polishing liquid, and more particularly to a chemical mechanical polishing liquid for flattening a barrier layer and a method of using the same.
在如今的積體電路製造領域內，互連技術的工藝標準不斷提高，具體表現為互連工藝的層數逐漸增加，同時其特徵尺寸不斷縮小，因此對矽片表面平整度的要求也越來越高。因為如果不能實現平坦化，則在半導體晶圓上創建複雜和密集的結構會非常有限，目前，化學機械拋光方法（CMP）是可實現整個矽片平坦化的最有效的方法。 CMP工藝是一種通過化學和機械力獲得表面平坦化的加工方法。典型的化學機械拋光方法主要利用固相反應的拋光原理，具體為，將襯底直接與旋轉拋光墊接觸，用一載重物在襯底背面施加壓力。在拋光期間，墊片和操作臺旋轉，同時在襯底背面保持向下的力，將磨料和化學活性溶液（通常稱為拋光液或拋光漿料）塗於墊片上，該拋光液與正在拋光的薄膜發生化學反應開始進行拋光過程。 然而，隨著積體電路技術向超深亞微米（32、28nm）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，就必須採用超低介電材料（ULK）來降低相鄰金屬線之間的寄生電容，目前較多採用超低介電材料為Coral，因此，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，還要具有較低的蝶形凹陷和拋光均一性才能保證更加可靠的電性能，特別是在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、封蓋氧化物，並能很好的停止在超低介電材料表面，形成互連線，而且對小尺寸圖形不敏感。這就對CMP提出了更高的挑戰，因為通常超低介電材料為參雜碳的氧化矽，其具有與二氧化矽相似的表面性，所以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，關於拋光液的報導可以分為鹼性與酸性兩類，例如CN1400266公開了一種鹼性阻擋層拋光液，該拋光液包含二氧化矽磨料、胺類化合物和非離子表面活性劑，該拋光液會對銅產生腐蝕；CN101372089A公開了一種鹼性阻擋層拋光液，該拋光液包含二氧化矽磨料、腐蝕抑制劑、氧化劑、非離子氟表面活性劑和芳族磺酸氧化劑化合物，該拋光液的阻擋層的拋光速率較低，且產率較低；CN101012356A公開了一種酸性阻擋層拋光液，該拋光液包含氧化劑、部分被鋁覆蓋的二氧化矽顆粒、抑制劑和絡合劑，該酸性拋光液存在對銅腐蝕嚴重的缺陷。 本發明旨在提供一種適合於ULK-銅互連制程中的阻擋層拋光液，其在較溫和的條件下具有高的阻擋層去除速率和超低介電材料介面的工藝停止特性，並能很好的控制蝶形凹陷，金屬腐蝕和表面污染物指標。In today's field of integrated circuit manufacturing, the process standards of interconnect technology continue to increase, as the number of layers of the interconnect process increases, and the feature size continues to shrink, so the requirements for the flatness of the surface of the batter are also increasing. The higher. Because if flattening is not possible, creating complex and dense structures on semiconductor wafers can be very limited. Currently, chemical mechanical polishing (CMP) is the most effective way to achieve flattening of the entire ruthenium. The CMP process is a process for obtaining surface flattening by chemical and mechanical forces. A typical chemical mechanical polishing method utilizes the polishing principle of a solid phase reaction, specifically, by directly contacting a substrate with a rotating polishing pad and applying a load on the back surface of the substrate with a load. During polishing, the gasket and the table rotate while maintaining a downward force on the back of the substrate, applying abrasive and chemically active solutions (often referred to as polishing fluids or polishing slurries) to the gasket. The polished film undergoes a chemical reaction to begin the polishing process. However, as integrated circuit technology develops toward ultra-deep sub-micron (32, 28 nm), the parasitic capacitance caused by the reduced feature size is more and more serious affecting the performance of the circuit. To reduce this effect, it must be adopted. Ultra-low dielectric materials (ULK) to reduce the parasitic capacitance between adjacent metal lines. Currently, ultra-low dielectric materials are used as Coral. Therefore, in addition to strict control of surface pollutants and metal corrosion during CMP In addition, it has a lower butterfly depression and polishing uniformity to ensure more reliable electrical performance, especially in the flattening process of the barrier layer, which needs to be quickly removed in a shorter time and under lower pressure. Layer metal, capping oxide, and well stop on the surface of ultra-low dielectric materials, forming interconnects, and insensitive to small size graphics. This poses a higher challenge for CMP because the ultra-low dielectric material is usually a carbon-doped cerium oxide, which has a similar surface property to cerium oxide. Therefore, to control the residual thickness of the stop layer, it is necessary to have The ability to control the strong selection ratio is also characterized by high stability and easy cleaning. At present, the reports on the polishing liquid can be classified into two types, alkaline and acidic. For example, CN1400266 discloses an alkaline barrier polishing liquid comprising a cerium oxide abrasive, an amine compound and a nonionic surfactant, and the polishing The liquid corrodes the copper; CN101372089A discloses an alkaline barrier polishing liquid comprising a cerium oxide abrasive, a corrosion inhibitor, an oxidizing agent, a nonionic fluorosurfactant, and an aromatic sulfonic acid oxidizing agent compound, the polishing liquid The barrier layer has a lower polishing rate and a lower yield; CN101012356A discloses an acidic barrier polishing liquid comprising an oxidizing agent, a partially covered cerium oxide particle covered with aluminum, an inhibitor and a complexing agent, the acid polishing The liquid has serious defects in copper corrosion. The present invention is directed to a barrier polishing fluid suitable for use in a ULK-copper interconnect process which has a high barrier removal rate and a process stop characteristic of an ultra-low dielectric material interface under milder conditions, and can be very Good control of butterfly depressions, metal corrosion and surface contamination indicators.
本發明所要解決的問題是提供一種適合於ULK-銅互連制程中的阻擋層拋光，具有高的阻擋層（TaN/Ta）的拋光速率，並滿足阻擋層拋光工藝中對二氧化矽（Teos）、銅和超低介電材料（ULK）的去除速率及去除速率選擇比的要求，且對半導體器件表面的缺陷有很強的矯正能力，拋光後污染物殘留少，自身穩定性高的拋光液。 本發明提供了一種應用於阻擋層平坦化的化學機械拋光液，該拋光液包含研磨顆粒、唑類化合物、有機膦酸、非離子表面活性劑和氧化劑。 其中，所述研磨顆粒為二氧化矽，研磨顆粒的含量為1~20wt%，更佳的為2~10wt%；研磨顆粒的粒徑較佳的為20~150nm，更佳的為30~120nm。 其中，所述唑類化合物較佳的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、巰基苯基四氮唑、苯並咪唑，萘並三唑、2-巰基-苯並噻唑。所述唑類化合物的含量較佳的為0.001~2wt%，更佳的為0.01~1wt%。 其中，所述有機膦酸較佳的選自下列中的一種或多種：羥基亞乙基二膦酸、氨基三亞甲基膦酸、乙二胺四亞甲基膦酸、二乙烯三胺五亞甲基膦酸、2-膦酸基丁烷-1,2,4-三膦酸、多氨基多醚基亞甲基膦酸等，所述有機膦酸的含量為0.001~2wt%，更佳的為0.01~1wt%。 其中，所述非離子表面活性劑較佳的選自下列中的一種或多種：C10~18
脂肪醇聚氧乙烯（n）醚(n=7~30)、C8~9
烷基酚聚氧乙烯（n）醚(n=8~200)、C12~18
脂肪胺聚氧乙烯（n）醚(n=10~60)、陶氏化學公司的TritonCF-10、陶氏化學公司的TritonCF-21、陶氏化學公司的TritonDF-12、陶氏化學公司的TritonDF-16和陶氏化學公司的TritonDF-18。所述非離子表面活性劑的含量較佳的為0.001~0.5wt%，更佳的為0.01~0.2wt%。 其中，所述氧化劑較佳的選自下列中的一種或多種：過氧化氫、過氧乙酸，過硫酸鉀、過硫酸銨。所述氧化劑的含量較佳的為0.01~5wt%，更佳的為0.1~2wt%。 其中，所述化學機械拋光液的pH值為8.0~12.0，更佳的為9.0~11.0。 另外，本發明的化學機械拋光液還可以包含pH調節劑和殺菌劑等其他本領域添加劑。 本發明的積極進步效果在於：本發明的化學機械拋光液可以滿足阻擋層拋光過程中對各種材料的拋光速率和選擇比要求，對半導體器件表面的缺陷有很強的矯正能力，能夠快速實現平坦化，提高工作效率，降低生產成本。The problem to be solved by the present invention is to provide a barrier polishing suitable for ULK-copper interconnection process, having a high barrier layer (TaN/Ta) polishing rate, and satisfying the barrier layer polishing process for cerium oxide (Teos) ), copper and ultra-low dielectric materials (ULK) removal rate and removal rate selection ratio requirements, and have strong correction ability on the surface defects of semiconductor devices, less residual pollutants after polishing, high self-stability polishing liquid. The present invention provides a chemical mechanical polishing liquid applied to the planarization of a barrier layer comprising abrasive particles, an azole compound, an organic phosphonic acid, a nonionic surfactant, and an oxidizing agent. Wherein, the abrasive particles are cerium oxide, the content of the abrasive particles is 1-20% by weight, more preferably 2-10% by weight; the particle size of the abrasive particles is preferably 20-150 nm, more preferably 30-120 nm. . Wherein the azole compound is preferably selected from one or more of the group consisting of benzotriazole, methylbenzotriazole, 5-phenyltetrazolium, nonylphenyltetrazolium, benzo Imidazole, naphthotriazole, 2-mercapto-benzothiazole. The content of the azole compound is preferably 0.001 to 2% by weight, more preferably 0.01 to 1% by weight. Wherein, the organic phosphonic acid is preferably selected from one or more of the following: hydroxyethylidene diphosphonic acid, aminotrimethylenephosphonic acid, ethylenediaminetetramethylenephosphonic acid, diethylenetriamine-5. Methylphosphonic acid, 2-phosphonobutane-1,2,4-triphosphonic acid, polyaminopolyethermethylenephosphonic acid, etc., the content of the organic phosphonic acid is 0.001 to 2% by weight, more preferably It is 0.01~1wt%. Wherein, the nonionic surfactant is preferably selected from one or more of the following: C 10-18 fatty alcohol polyoxyethylene (n) ether (n = 7 ~ 30), C 8 ~ 9 alkyl phenol poly Oxyethylene (n) ether (n=8~200), C 12~18 fatty amine polyoxyethylene (n) ether (n=10~60), Dow Chemical Company's Triton CF-10, Dow Chemical Company's TritonCF -21, Triton DF-12 from The Dow Chemical Company, Triton DF-16 from The Dow Chemical Company and Triton DF-18 from The Dow Chemical Company. The content of the nonionic surfactant is preferably from 0.001 to 0.5% by weight, more preferably from 0.01 to 0.2% by weight. Wherein, the oxidizing agent is preferably selected from one or more of the following: hydrogen peroxide, peracetic acid, potassium persulfate, ammonium persulfate. The content of the oxidizing agent is preferably from 0.01 to 5% by weight, more preferably from 0.1 to 2% by weight. Wherein, the chemical mechanical polishing liquid has a pH of 8.0 to 12.0, more preferably 9.0 to 11.0. Further, the chemical mechanical polishing liquid of the present invention may further contain other additives in the field such as a pH adjuster and a bactericide. The positive progress of the invention is that the chemical mechanical polishing liquid of the invention can meet the polishing rate and the selection ratio requirement of various materials in the polishing process of the barrier layer, has strong correction ability on the surface defects of the semiconductor device, and can quickly achieve flatness. Improve work efficiency and reduce production costs.
下面通過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所述的實施例範圍之中。 表1給出了對比拋光液1~3和本發明的拋光液1~15的各組分配比，按表中所給的配方，將除氧化劑以外的其他組分混合均勻，用KOH或HNO3
調節到所需要的pH值。使用前加氧化劑，並用水補充總量至100wt%，混合均勻即可得到所需的拋光液。 本發明所用試劑及原料均市售可得。 表1 對比拋光液1~3和本發明的拋光液1~15的配方
效果實施例1 採用對比拋光液1~3和本發明的拋光液1~9按照下述條件對銅(Cu)、鉭（Ta）、二氧化矽（TEOS）和超低介電材料（ULK）進行拋光。拋光條件：拋光機台為8’’Mirra機台，拋光墊為Fujibo pad，下壓力為1.5psi，轉速為拋光盤/拋光頭=93/87rpm，拋光液流速為150ml/min，拋光時間為1min。 表2 對比拋光液1~3和本發明拋光液1~9對銅(Cu)、鉭（Ta）、二氧化矽（TEOS）和超低介電材料（ULK）的去除速率及拋光效果
由表2可見，與對比拋光液1和對比拋光液2相比，本發明的拋光液可以獲得較高的阻擋層Ta和二氧化矽（TEOS）的去除速率，同時獲得較低的超低介電材料ULK的去除速率，能在拋光過程中較好的停止在超低介電材料ULK的表面。與對比拋光液3相比，使用二氧化矽作為研磨顆粒，能夠獲得無劃傷的銅的表面。 效果實施例2 採用對比拋光液1~2和本發明的拋光液1~7按照下述條件對帶有圖案的銅晶片進行拋光。拋光條件：拋光機台為8’’Mirra機台，拋光墊為Fujibo pad，下壓力為1.5psi，轉速為拋光盤/拋光頭=93/87rpm，拋光液流速為150ml/min，拋光時間為1min。 表3 對比拋光液1~2和本發明拋光液1~7對帶有圖案的銅晶片拋光後的矯正能力對比
其中，表中Dishing，是指阻擋層拋光前在金屬墊上的蝶形凹陷（埃），Erosion是指阻擋層在細線區域（50%line）上的侵蝕（埃），∆(Å)是指拋光後的矯正能力值。 由表3可以看出，與對比拋光液1和對比拋光液2相比，本發明的拋光液能較好的修正前程在晶圓上產生的碟形凹陷和侵蝕，獲得了較好的晶圓形貌。 應當理解的是，本發明所述wt%均指的是重量百分含量。 以上對本發明的具體實施例進行了詳細描述，但其只是作為範例，本發明並不限制於以上描述的具體實施例。對於本領域技術人員而言，任何對本發明進行的等同修改和替代也都在本發明的範疇之中。因此，在不脫離本發明的精神和範圍下所作的均等變換和修改，都應涵蓋在本發明的範圍內。The invention is further illustrated by the following examples, which are not intended to limit the invention. Table 1 shows the distribution ratios of the comparative polishing liquids 1-3 and the polishing liquids 1 to 15 of the present invention. According to the formulation given in the table, the components other than the oxidizing agent are uniformly mixed, using KOH or HNO 3 Adjust to the desired pH. Add the oxidizing agent before use, and add the total amount to 100% by weight with water, and mix well to obtain the desired polishing liquid. The reagents and starting materials used in the present invention are commercially available. Table 1 Formulation of Comparative Polishing Liquid 1~3 and Polishing Liquid 1~15 of the Present Invention Effect Example 1 Comparative polishing liquids 1 to 3 and polishing liquids 1 to 9 of the present invention were used for copper (Cu), tantalum (Ta), cerium oxide (TEOS) and ultra-low dielectric materials (ULK) according to the following conditions. Polished. Polishing conditions: polishing machine is 8''Mirra machine, polishing pad is Fujibo pad, lower pressure is 1.5 psi, rotation speed is polishing plate/buffing head=93/87 rpm, polishing liquid flow rate is 150ml/min, polishing time is 1min . Table 2 Comparison of removal rate and polishing effect of copper (Cu), tantalum (Ta), cerium oxide (TEOS) and ultra-low dielectric material (ULK) with polishing liquid 1~3 and polishing liquid 1~9 of the present invention It can be seen from Table 2 that the polishing liquid of the present invention can obtain a higher removal rate of the barrier layer Ta and cerium oxide (TEOS) than the comparative polishing liquid 1 and the comparative polishing liquid 2, and at the same time obtain a lower ultra-low medium. The removal rate of the electrical material ULK can be better stopped on the surface of the ultra-low dielectric material ULK during polishing. Compared with the comparative polishing liquid 3, using ceria as the abrasive particles, the surface of the scratch-free copper can be obtained. Effect Example 2 A patterned copper wafer was polished using the comparative polishing liquids 1-2 and the polishing liquids 1 to 7 of the present invention under the following conditions. Polishing conditions: polishing machine is 8''Mirra machine, polishing pad is Fujibo pad, lower pressure is 1.5 psi, rotation speed is polishing plate/buffing head=93/87 rpm, polishing liquid flow rate is 150ml/min, polishing time is 1min . Table 3 Comparison of Correction Ability of Polished Liquid 1~2 and Polished Liquid 1~7 of Patterned Polished Copper Wafer Among them, Dishing in the table refers to the butterfly depression (A) on the metal pad before the barrier layer is polished, Erosion refers to the erosion of the barrier layer on the thin line region (50% line), and ∆ (Å) refers to polishing. The value of the corrective ability afterwards. As can be seen from Table 3, compared with the comparative polishing liquid 1 and the comparative polishing liquid 2, the polishing liquid of the present invention can better correct the dishing and erosion generated on the wafer by the prode to obtain a better wafer. Morphology. It should be understood that the wt% of the present invention refers to a weight percentage. The specific embodiments of the present invention have been described in detail above, but are merely exemplary, and the invention is not limited to the specific embodiments described above. Any equivalent modifications and substitutions to the invention are also within the scope of the invention. Accordingly, equivalents and modifications may be made without departing from the spirit and scope of the invention.
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