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
本發明涉及半導體製造領域，尤其涉及一種可應用於阻擋層平坦化的化學機械拋光液。The invention relates to the field of semiconductor manufacturing, and in particular to a chemical mechanical polishing liquid which can be applied to the planarization of a barrier layer.
目前，在積體電路製造中，隨著互連技術的標準的不斷提高、互連層數不斷增加、工藝特徵尺寸不斷縮小，對矽片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工藝就是使用一種含磨料的混合物和拋光墊拋光積體電路表面。在典型的化學機械拋光方法中，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。 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拋光均一性才能保證更加可靠的電性能，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，介電層氧化物並能很好的停止在低介電材料表面，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拋光液，如，CN1400266公開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，其在拋光後，會對銅金屬層產生腐蝕；CN101372089A公開一種鹼性阻擋層拋光液，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，其對阻擋層拋光速率較低，拋光效率低；CN101012356A公開一種酸性阻擋層拋光液，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；另外，CN104830235A公開了一種用於鈷阻擋層結構的化學機械拋光液，其含有研磨顆粒，氧化劑，金屬錯合劑，金屬緩蝕劑，表面活性劑和水，通過加入非離子表面活性劑去降低鈷的去除速率，進一步減少鈷的腐蝕，但此發明未提及拋光液對二氧化矽，低介電材料的去除效果。 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-銅互連制程中的阻擋層拋光，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工藝停止特性，同時能很好的控制碟型凹陷(Dishing)、介質層侵蝕(Erosion)、金屬腐蝕和表面污染物的化學機械拋光液是本行業亟待解決解決的問題。At present, in the manufacture of integrated circuits, as the standards of interconnect technology continue to increase, the number of interconnect layers continues to increase, and the size of process features continues to shrink, the requirements for the flatness of the surface of the cymbal are also increasing. 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 cymbal. The CMP process uses an abrasive-containing mixture and a polishing pad to polish the integrated circuit surface. In a typical chemical mechanical polishing process, the substrate is placed in direct contact with a rotating polishing pad and a load is applied to the backside 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. 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, low-medium must be used. Electrical materials to reduce the parasitic capacitance between adjacent metal lines. Currently, low dielectric materials are used for BD (Black Diamond). In addition to strict control of surface contamination indicators and metal corrosion in the CMP process, Lower dishing and polishing uniformity ensure more reliable electrical performance, especially in the planarization of the barrier layer, which requires rapid removal of the barrier metal in a shorter time and lower pressure, dielectric layer oxidation The material stops well on the surface of the low dielectric material, forms interconnects, and is insensitive to small size patterns. This poses a higher challenge for CMP, because usually the low dielectric material is carbon doped cerium oxide. To control the residual thickness of the stop layer, it is necessary to have a strong selectivity ratio control ability, and there is still a very high High stability and easy to clean features. There are many chemical mechanical polishing liquids on the market that are used for the planarization of barrier layers. For example, CN1400266 discloses an alkaline barrier polishing liquid comprising cerium oxide abrasive, an amine compound and a nonionic surfactant. Corrosion of the copper metal layer after polishing; CN101372089A discloses an alkaline barrier polishing liquid containing cerium oxide abrasive, corrosion inhibitor, oxidizing agent, nonionic fluorosurfactant, aromatic sulfonic acid oxidizing agent compound, Low barrier polishing rate and low polishing efficiency; CN101012356A discloses an acidic barrier polishing liquid comprising an oxidizing agent, a partially covered cerium oxide particle covered with aluminum, an inhibitor and a crosslinking agent, which have severe corrosion to the copper metal layer In addition, CN104830235A discloses a chemical mechanical polishing liquid for a cobalt barrier structure containing abrasive particles, an oxidizing agent, a metal complexing agent, a metal corrosion inhibitor, a surfactant and water, which are reduced by adding a nonionic surfactant. The removal rate of cobalt further reduces the corrosion of cobalt, but this invention does not mention the slurry to dioxane Silicon, removal of the low dielectric material. Therefore, in view of the problems in the prior art, a barrier polishing capable of being suitable for a low dielectric material-copper interconnection process is sought, and a high barrier removal rate and a low dielectric material can be realized under milder conditions. The process stop characteristics of the interface, as well as the chemical mechanical polishing liquid which can well control dishing, Erosion, metal corrosion and surface contaminants, are urgent problems to be solved in the industry.
為解決上述問題，本發明提供一種阻擋層化學機械拋光液，其在較溫和的條件下具有高的阻擋層材料、介電層材料去除速率和可調的低介電層材料、銅的去除速率，並能在拋光過程中很好的控制碟型凹陷(Dishing)、介質層侵蝕(Erosion)、金屬腐蝕的產生，以及減少表面污染物。 具體地，本發明提供了一種用於阻擋層平坦化的化學機械拋光液，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，所述非離子表面活性劑為聚乙二醇。 其中，所述研磨顆粒為二氧化矽顆粒；研磨顆粒的品質百分比濃度較佳的為2~20%，更佳的為5~15%；所述的研磨顆粒的粒徑較佳的為10~250nm，更佳的為50~200nm。 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、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。所述的唑類化合物的品質百分比濃度較佳的為0.001~1%，更佳的為0.01~0.5%。 其中，錯合劑選自有機羧酸、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/或乙二胺，所述的錯合劑的品質百分比的濃度較佳的為0.001~2%，更佳的為0.01~1%。 其中，所述非離子表面活性劑選自聚乙二醇。所述聚乙二醇的分子量較佳的為200~20000，更佳的為400~10000。所述聚乙二醇的品質百分比濃度較佳的為0.001~1.0%，更佳的為0.01~0.5%。 其中，所述氧化劑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。所述的氧化劑的品質百分比濃度較佳的為0.01~5%，更佳的為0.1~2%。 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調節劑和殺菌劑等添加劑。 且，本發明的化學機械拋光液可以濃縮製備，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： 1) 其在較溫和的條件下具有高的阻擋層材料、介電層材料的去除速率和可調的低介電材料、銅的去除速率； 2) 其能在拋光過程中很好的控制碟型凹陷(Dishing)、介質層侵蝕(Erosion)、金屬腐蝕的產生，以及減少表面污染物。 3) 其可濃縮製備，方便儲存以及運輸和使用。In order to solve the above problems, the present invention provides a barrier chemical mechanical polishing liquid having a high barrier material, a dielectric layer material removal rate, and an adjustable low dielectric layer material, copper removal rate under milder conditions. And can well control dishing, Erosion, metal corrosion, and reduce surface contamination during polishing. Specifically, the present invention provides a chemical mechanical polishing liquid for barrier layer planarization comprising abrasive particles, an azole compound, a binder, a nonionic surfactant, and an oxidizing agent, wherein the nonionic surfactant is Polyethylene glycol. Wherein, the abrasive particles are cerium oxide particles; the percentage of the mass of the abrasive particles is preferably 2 to 20%, more preferably 5 to 15%; and the particle size of the abrasive particles is preferably 10~ 250 nm, more preferably 50 to 200 nm. Wherein the azole compound is preferably selected from one or more of the group consisting of benzotriazole, methylbenzotriazole, 5-phenyltetrazolium, 5-amino-tetrazole, fluorenyl Phenyltetrazole, benzimidazole, naphthotriazole and 2-mercapto-benzothiazole. The percentage by mass of the azole compound is preferably 0.001 to 1%, more preferably 0.01 to 0.5%. Wherein the complexing agent is selected from one or more of an organic carboxylic acid, an organic phosphonic acid, an amino acid and an organic amine, preferably one or more selected from the group consisting of acetic acid, propionic acid, oxalic acid, malonic acid, and succinic acid. , citric acid, ethylenediaminetetraacetic acid, 2-phosphonic acid butane-1,2,4-tricarboxylic acid, aminotrimethylene phosphonic acid, hydroxyethylidene diphosphonic acid, ethylenediaminetetramethylene phosphonic acid, glycine And/or ethylenediamine, the concentration of the mass percentage of the complexing agent is preferably 0.001 to 2%, more preferably 0.01 to 1%. Wherein the nonionic surfactant is selected from the group consisting of polyethylene glycol. The polyethylene glycol preferably has a molecular weight of from 200 to 20,000, more preferably from 400 to 10,000. The percentage by mass of the polyethylene glycol is preferably 0.001 to 1.0%, more preferably 0.01 to 0.5%. Wherein the oxidizing agent is selected from one or more of the group consisting of hydrogen peroxide, peracetic acid, potassium persulfate and ammonium persulfate, preferably hydrogen peroxide. The percentage by mass of the oxidizing agent is preferably from 0.01 to 5%, more preferably from 0.1 to 2%. 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 an additive such as a pH adjuster and a bactericide. Further, the chemical mechanical polishing liquid of the present invention can be prepared by concentration, diluted with deionized water in use, and added with an oxidizing agent to the concentration range of the present invention. Compared with the prior art, the technical advantages of the present invention are as follows: 1) it has high barrier material, removal rate of dielectric layer material and adjustable low dielectric material, copper removal rate under milder conditions; 2) It can well control dishing, Erosion, metal corrosion and reduce surface contamination during polishing. 3) It can be concentrated and prepared for convenient storage and transportation and use.
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1~2和本發明的拋光液1~13的配方，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，混合均勻即可。水為餘量。 表1 對比拋光液1~2和本發明的拋光液1~13
效果實施例1 採用對比拋光液1~2和本發明的拋光液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)進行拋光。拋光條件：拋光機台為12” Reflexion LK 機台，拋光墊為Fujibo pad，下壓力為1.5psi，轉速為拋光盤/拋光頭=113/107rpm，拋光液流速為300ml/min，拋光時間為1min。 表2 對比拋光液1~2和本發明拋光液1~9對銅(Cu)、鉭(Ta)、 二氧化矽(TEOS)和低介電材料(BD)的去除速率
由表2可見，與對比拋光液1與2相比，本發明的拋光液可以獲得較高的阻擋層材料Ta和介電層材料二氧化矽(TEOS)的去除速率，可以縮短拋光時間，提高產能，同時通過添加不同量的聚乙二醇表面活性劑，將低介電材料BD的去除速率控制在比二氧化矽TEOS低，有利於控制圖形晶片的拋光過程和拋光後的低介電材料BD剩餘厚度，並保證晶片的表面均一性。 效果實施例2 採用對比拋光液2和本發明的拋光液1~3按照下述條件對帶有圖案的銅晶片進行拋光。該圖形晶片為市售的12英寸Sematech754圖形晶片，膜層材料從上至下為銅/鉭/氮化鉭/TEOS/BD，拋光過程分三步，第一步用市售的銅拋光液去除大部分的銅，第二步用市售的銅拋光液去除殘留的銅，第三步用本發明的阻擋層拋光液將阻擋層(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。阻擋層拋光液拋光條件：拋光機台為12”Reflexion LK機台，拋光墊為Fujibo pad，下壓力為1.5psi，轉速為拋光盤/拋光頭=113/107rpm，拋光液流速為300ml/min，拋光時間為70s。 表3 對比拋光液2和本發明拋光液1~3對帶有圖案的銅晶片拋光後的矯正能力對比
其中，上文中所述Dishing，是指阻擋層拋光前在金屬墊上的碟型凹陷，Erosion是指阻擋層線上寬為0.18微米，密度為50%的密線區域(50%銅/50%介電層)上的介質層侵蝕，∆(埃)是指拋光後的矯正能力值。 由表3可以看出，與對比拋光液2相比，本發明的拋光液由於抑制了低介電材料BD的去除速率，能很好地停止在BD上，有效的控制了圖形晶片的拋光過程和保證了拋光後的BD剩餘厚度，能較好的修正前程(銅拋光後)在晶圓上產生的碟型凹陷和介質層侵蝕，獲得了較好的晶圓形貌。 效果實施例3 採用對比拋光液1和拋光液1按照下述條件對帶有圖案的銅晶片進行拋光。該圖形晶片為市售的12英寸Sematech754圖形晶片，膜層材料從上至下為銅/鉭/氮化鉭/TEOS/BD，拋光過程分三步，第一步用市售的銅拋光液去除大部分的銅，第二步用市售的銅拋光液去除殘留的銅，第三步用本發明的阻擋層拋光液將阻擋層(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分別採用對比拋光液1和拋光液1拋光後Sematech 754圖形測試晶圓的表面形貌的SEM圖。對比可以看出，本發明的拋光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，圖形片經過本發明的拋光液拋光後，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。The invention is further illustrated by the following examples, which are not intended to limit the invention. Table 1 shows the formulation of the comparative polishing liquid 1~2 and the polishing liquid 1~13 of the present invention. According to the formula given in the table, the components other than the oxidizing agent are uniformly mixed and adjusted with KOH or HNO 3 . The pH required. Add oxidizing agent before use and mix well. Water is the balance. Table 1 Comparative polishing liquid 1~2 and polishing liquid 1~13 of the present invention Effect Example 1 Comparative polishing liquid 1 to 2 and polishing liquid 1 to 9 of the present invention were used for copper (Cu), barrier material tantalum (Ta), dielectric material cerium oxide (TEOS) and low medium according to the following conditions. The electrical material (BD) is polished. Polishing conditions: polishing machine is 12" Reflexion LK machine, polishing pad is Fujibo pad, lower pressure is 1.5 psi, rotation speed is polishing disk / polishing head = 113/107 rpm, polishing liquid flow rate is 300ml/min, polishing time is 1min Table 2 Comparison of the removal rates of copper (Cu), tantalum (Ta), cerium oxide (TEOS) and low dielectric material (BD) from the polishing liquid 1~2 and the 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 material Ta and the dielectric layer material cerium oxide (TEOS) than the comparative polishing liquids 1 and 2, which can shorten the polishing time and improve the polishing time. Capacity, while adding different amounts of polyethylene glycol surfactant, the removal rate of low dielectric material BD is lower than that of cerium oxide TEOS, which is beneficial to control the polishing process of the patterned wafer and the polished low dielectric material. The BD has a remaining thickness and ensures surface uniformity of the wafer. Effect Example 2 A patterned copper wafer was polished using the comparative polishing liquid 2 and the polishing liquids 1 to 3 of the present invention under the following conditions. The graphic wafer is a commercially available 12-inch Sematech 754 graphics wafer. The material of the film is copper/germanium/tantalum nitride/TEOS/BD from top to bottom. The polishing process is divided into three steps. The first step is to remove the commercially available copper polishing solution. Most of the copper, the second step uses a commercially available copper polishing solution to remove residual copper, and the third step uses the barrier polishing fluid of the present invention to block the barrier layer (钽/tantalum nitride), cerium oxide TEOS, and partially low The dielectric material BD is removed and stopped on the BD layer. Barrier polishing solution polishing conditions: the polishing machine is a 12" Reflexion LK machine, the polishing pad is Fujibo pad, the lower pressure is 1.5 psi, the rotation speed is polishing disk / polishing head = 113/107 rpm, and the polishing liquid flow rate is 300 ml/min. Polishing time is 70s. Table 3 Comparison of the correction ability of the polishing liquid 2 and the polishing liquid 1~3 of the invention after polishing the patterned copper wafer Among them, Dishing mentioned above refers to the dish-shaped recess on the metal pad before the barrier layer is polished, and Erosion refers to the dense line region (50% copper/50% dielectric) with a width of 0.18 μm and a density of 50% on the barrier layer. The dielectric layer on the layer is eroded, and ∆ (Angstrom) refers to the value of the corrective ability after polishing. As can be seen from Table 3, compared with the comparative polishing liquid 2, the polishing liquid of the present invention can stop the polishing process of the graphic wafer effectively by suppressing the removal rate of the low dielectric material BD. And to ensure the remaining thickness of the polished BD, it can better correct the dishing and dielectric layer erosion generated on the wafer by the precursor (after copper polishing), and obtain a better crystal round appearance. Effect Example 3 The patterned copper wafer was polished using the comparative polishing liquid 1 and the polishing liquid 1 under the following conditions. The graphic wafer is a commercially available 12-inch Sematech 754 graphics wafer. The material of the film is copper/germanium/tantalum nitride/TEOS/BD from top to bottom. The polishing process is divided into three steps. The first step is to remove the commercially available copper polishing solution. Most of the copper, the second step uses a commercially available copper polishing solution to remove residual copper, and the third step uses the barrier polishing fluid of the present invention to block the barrier layer (钽/tantalum nitride), cerium oxide TEOS, and partially low The dielectric material BD is removed and stopped on the BD layer. Fig. 1 and Fig. 2 are SEM images of the surface topography of the Sematech 754 pattern test wafer after polishing of the polishing liquid 1 and the polishing liquid 1, respectively. It can be seen from the comparison that the polishing liquid of the invention effectively inhibits metal corrosion, especially the copper wire region, and the graphic film is polished and polished, and the surface is still clear and sharp, and no metal corrosion phenomenon is found. And no pollution particles remain. It should be noted that the embodiments of the present invention are preferred embodiments, and are not intended to limit the scope of the present invention. Any one skilled in the art may use the above-disclosed technical contents to change or modify the equivalent embodiments. Any modification or equivalent changes and modifications of the above embodiments in accordance with the technical spirit of the present invention are still within the scope of the technical solutions of the present invention.
圖1為採用對比拋光液1拋光後Sematech754圖形晶片的表面形貌的SEM圖； 圖2為採用拋光液1拋光後Sematech754圖形晶片的表面形貌的SEM圖。1 is an SEM image of the surface topography of a Sematech 754 patterned wafer polished with a comparative polishing liquid 1; FIG. 2 is an SEM image of the surface topography of a Sematech 754 patterned wafer polished with a polishing liquid 1.