用於阻擋層平坦化的化學機械拋光液Chemical Mechanical Polishing Fluids for Barrier Planarization
本發明係涉及一種化學機械拋光液領域，尤指一種可用於阻擋層平坦化的化學機械拋光液。The present invention relates to the field of chemical mechanical polishing liquid, and in particular, to a chemical mechanical polishing liquid that can be used for planarizing barrier layers.
在積體電路製造中，內連線技術的標準在提高，隨著內連線層數的增加和製程特徵尺寸的縮小，對矽晶圓表面平整度的要求也越來越高，如果沒有平坦化的能力，在半導體晶圓上製作複雜和密集的結構是非常有限的，化學機械拋光（CMP）製程就是可實現整個矽晶圓平坦化的最有效的方法。 CMP製程就是一種使用含研磨顆粒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，將基底直接與旋轉拋光墊接觸，用一載重物在基底背面施加壓力。在拋光期間，旋轉墊片和操作臺，同時在基底背面保持向下的力，將研磨顆粒和化學活性溶液（通常稱為拋光液或拋光漿料）塗於墊片上，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（如：32nm、28nm）的方向發展，特徵尺寸的減小，導致了寄生電容愈加嚴重地影響著電路的性能。為減小這一影響，需要採用低介電材料來降低相鄰金屬線之間的寄生電容。目前，常用的低介電材料為BD（Black Diamond），在其CMP製程過程中，除了要嚴格控制表面污染物指標、杜絕金屬腐蝕外，還要具備較低的蝶形凹陷和均一的拋光才能保證更可靠的電性能。尤其在其阻擋層的平坦化過程中，移除阻擋層的金屬需要在更短的時間和更低的壓力下快速完成；此外，移除阻擋層的同時還需要移除封蓋氧化物並能很好地停止在低介電材料表面，形成內連線，並且對小尺寸圖形不敏感。這對CMP提出了更高的要求，因為低介電材料為摻雜碳的氧化矽，與二氧化矽具有相似的表面性，要控制停止層的殘留厚度，就要求拋光液具有對去除速率選擇比具備強的調控能力、高穩定性及易清洗等特徵。 現有技術中，CN1400266A公開一種鹼性化學機械拋光液，其包含二氧化矽磨料、錯合劑、胺類化合物螯合劑和非離子表面活性劑，其用於阻擋層拋光時無法避免對銅金屬層的腐蝕現象；專利CN101372089A公開一種化學機械拋光漿料，其包含二氧化矽研磨顆粒、腐蝕抑制劑、氧化劑、非離子氟表面活性劑、芳族磺酸氧化劑表面化合物，其克服了對銅金屬層的腐蝕，但是拋光速率低，拋光效率不高；專利CN1688665A公開一種化學機械拋光漿料，其包含研磨劑、兩親性非離子表面活性劑、有機酸、腐蝕抑制劑，該兩親性非離子表面活性劑的加入，提高了銅相對於二氧化矽的去除速率的選擇比，但是降低了二氧化矽的拋光速率，且阻擋層去除速率不高。 因此，提供一種適於低介電材料-銅內連線製程中的阻擋層拋光液，在較溫和的條件下具有高的阻擋層去除速率和低介電材料介面的製程停止特性，並能很好的控制蝶形凹陷，金屬腐蝕和表面污染物指標的拋光液是本領域亟待解決的問題。In integrated circuit manufacturing, the standards of interconnection technology are improving. As the number of interconnection layers increases and the process feature size shrinks, the requirements for the surface flatness of silicon wafers are also getting higher and higher. If there is no flatness, The ability to fabricate complex and dense structures on semiconductor wafers is very limited. The chemical mechanical polishing (CMP) process is the most effective method to achieve planarization of the entire silicon wafer. The CMP process uses a mixture containing abrasive particles and a polishing pad to polish the surface of an integrated circuit. In a typical chemical mechanical polishing method, the substrate is placed in direct contact with a rotating polishing pad and a weight is used to apply pressure on the backside of the substrate. During polishing, the pad and table are rotated while maintaining a downward force on the back of the substrate, applying abrasive particles and a chemically active solution (often called polishing fluid or polishing slurry) to the pad that is in contact with the polishing fluid being polished. A chemical reaction occurs in the film and the polishing process begins. As integrated circuit technology develops towards ultra-deep sub-micron (such as 32nm, 28nm), the feature size decreases, causing parasitic capacitance to more seriously affect the performance of the circuit. To reduce this effect, low dielectric materials need to be used to reduce the parasitic capacitance between adjacent metal lines. Currently, the commonly used low-dielectric material is BD (Black Diamond). During its CMP process, in addition to strictly controlling surface contaminant indicators and eliminating metal corrosion, it must also have low butterfly dents and uniform polishing capabilities. Guarantee more reliable electrical performance. Especially in the planarization process of the barrier layer, the metal removal of the barrier layer needs to be completed quickly and under lower pressure; in addition, when removing the barrier layer, the capping oxide also needs to be removed and the Stops well on low dielectric material surfaces, forms interconnects, and is insensitive to small pattern sizes. This puts forward higher requirements for CMP, because the low dielectric material is carbon-doped silicon oxide, which has similar surface properties to silicon dioxide. To control the residual thickness of the stop layer, the polishing fluid is required to have a selective removal rate. It has the characteristics of strong control ability, high stability and easy cleaning. In the prior art, CN1400266A discloses an alkaline chemical mechanical polishing liquid, which contains silica abrasives, complexing agents, amine compound chelating agents and non-ionic surfactants. When used for barrier layer polishing, it cannot avoid damaging the copper metal layer. Corrosion phenomenon; Patent CN101372089A discloses a chemical mechanical polishing slurry, which contains silica abrasive particles, corrosion inhibitors, oxidants, non-ionic fluorine surfactants, and aromatic sulfonic acid oxidant surface compounds, which overcomes the corrosion of the copper metal layer. Corrosion, but the polishing rate is low and the polishing efficiency is not high; patent CN1688665A discloses a chemical mechanical polishing slurry, which contains an abrasive, an amphiphilic nonionic surfactant, an organic acid, and a corrosion inhibitor. The amphiphilic nonionic surface The addition of activator increases the selectivity ratio of copper to silicon dioxide removal rate, but reduces the polishing rate of silicon dioxide, and the barrier layer removal rate is not high. Therefore, a barrier layer polishing liquid suitable for the low dielectric material-copper interconnection process is provided, which has a high barrier layer removal rate and process stop characteristics of the low dielectric material interface under relatively mild conditions, and can easily Polishing fluids that can effectively control butterfly dents, metal corrosion and surface contaminants are issues that need to be solved urgently in this field.
本發明旨在提供一種適於低介電材料-銅內連線製程中的阻擋層拋光液，在較溫和的條件下具有高的阻擋層去除速率及低介電材料介面的製程停止特性，並且能有效控制蝶形凹陷，金屬腐蝕和表面污染物現象。 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，該拋光液包含研磨顆粒、唑類化合物、錯合劑、矽氧烷類表面活性劑和氧化劑。 其中，所述矽氧烷類表面活性劑的化學式為：；其中，Me=CH3
，0≤m≤50，0≤n≤50；R=NHCH2
CHCH2
，CH2
CH2
COOH或(CH2
)3
O(C2
H4
O)x
H，0≤x≤100。 其中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/或2-巰基-苯並噻唑。所述的唑類化合物的重量百分比濃度較佳的為0.001~1%，更佳的為0.01~0.5%。 其中錯合劑為有機羧酸、有機膦酸、氨基酸和/或有機胺，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，所述的錯合劑的重量百分比的濃度較佳的為0.001~2%，更佳的為0.01~1%。 其中聚矽氧烷類表面活性劑的重量百分比濃度較佳的為：0.001~1.0%，更佳的為0.01~0.5%。 其中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/或過硫酸銨。較佳為過氧化氫，所述的氧化劑的重量百分比濃度較佳的為0.01~5%，更佳的為0.1~2%。 其中所述的化學機械拋光液的PH值為8.0~12.0，更佳的為9.0~11.0。 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： 本發明通過添加特定結構的矽氧烷類表面活性劑，提供一種適於低介電材料-銅內連線製程中的阻擋層拋光液，其可在較溫和的條件下實現高的阻擋層去除速率及低介電材料介面的製程停止特性，並且能有效控制蝶形凹陷，金屬腐蝕和表面污染物等。The present invention aims to provide a barrier layer polishing liquid suitable for the low dielectric material-copper interconnection process, which has a high barrier layer removal rate and process stop characteristics of the low dielectric material interface under relatively mild conditions, and It can effectively control butterfly dents, metal corrosion and surface contaminants. Specifically, the present invention provides a chemical mechanical polishing liquid for barrier layer planarization, which polishing liquid contains abrasive particles, azole compounds, complexing agents, siloxane surfactants and oxidants. Wherein, the chemical formula of the siloxane surfactant is: ; Among them, Me=CH 3 , 0≤m≤50, 0≤n≤50; R=NHCH 2 CHCH 2 , CH 2 CH 2 COOH or (CH 2 ) 3 O(C 2 H 4 O) x H, 0 ≤x≤100. The abrasive particles are silica particles; the weight percentage concentration of the abrasive particles is preferably 2 to 20%, more preferably 5 to 15%; the particle size of the abrasive particles is preferably 10 to 250 nm, more preferably The best is 50~200nm. Among the azole compounds, one or more of the following are preferably selected: benzotriazole, methylbenzotriazole, 5-phenyltetrazole, 5-amino-tetrazole, mercaptophenyl Tetrazole, benzimidazole, naphthotriazole and/or 2-mercapto-benzothiazole. The weight percentage concentration of the azole compound is preferably 0.001~1%, and more preferably 0.01~0.5%. The complexing agent is organic carboxylic acid, organic phosphonic acid, amino acid and/or organic amine, preferably selected from one or more of the following: acetic acid, propionic acid, oxalic acid, malonic acid, succinic acid, citric acid, ethanol Diamine tetraacetic acid, 2-phosphonic acid butane-1,2,4-tricarboxylic acid, aminotrimethylenephosphonic acid, hydroxyethylidenediphosphonic acid, ethylenediaminetetramethylenephosphonic acid, glycine and/or ethanol For diamine, the concentration of the weight percentage of the complexing agent is preferably 0.001~2%, more preferably 0.01~1%. Among them, the weight percentage concentration of the polysiloxane surfactant is preferably 0.001~1.0%, and more preferably 0.01~0.5%. The oxidizing agent is selected from one or more of the following: hydrogen peroxide, peracetic acid, potassium persulfate and/or ammonium persulfate. Hydrogen peroxide is preferred, and the weight percentage concentration of the oxidizing agent is preferably 0.01 to 5%, and more preferably 0.1 to 2%. The pH value of the chemical mechanical polishing liquid is 8.0~12.0, preferably 9.0~11.0. The chemical mechanical polishing liquid of the present invention may also contain other additives in the field such as pH adjusters and bactericides. 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 advantages of the present invention are: By adding a siloxane surfactant with a specific structure, the present invention provides a barrier layer polishing liquid suitable for the low dielectric material-copper interconnection process. It can achieve high barrier layer removal rate and process stop characteristics of low dielectric material interface under milder conditions, and can effectively control butterfly depression, metal corrosion and surface contamination, etc.
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，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)、鉭（Ta）、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Ta和二氧化矽（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矽氧烷類表面活性劑，將低介電材料BD的去除速率控制在比TEOS低，有利於控制圖形晶片的拋光過程和拋光後的BD剩餘厚度，並保證晶片的表面均一性，而且通過添加不同量的矽氧烷類表面活性劑，可在不影響阻擋層和二氧化矽（TEOS）的去除速率的條件下調節介電材料BD的去除速率，滿足不同製程條件下的技術要求。 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，碟形凹陷為阻擋層拋光前在金屬墊上的碟形凹陷；介質層侵蝕為阻擋層線上寬為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，∆(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2相比，本發明的拋光液由於抑制了BD的去除速率，能較好的修正前程（銅拋光後）在晶圓上產生的碟形凹陷和侵蝕，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Sematech754圖形晶片的表面形貌的SEM圖。圖3和圖4分別採用對比拋光液1和拋光液1浸漬30分鐘後Sematech 754圖形晶片的表面形貌的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，Sematech 754圖形晶片經過本發明的拋光液拋光後和浸漬後，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。 應當理解的是，本發明所述wt%均指的是重量百分比濃度。 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 present invention is further described below by means of examples, but the present invention is not limited to the scope of the described examples. Table 1 shows the comparative polishing slurries 1 to 2 and the polishing slurries 1 to 13 of the present invention. According to the formula given in the table, mix the other components except the oxidant evenly, and use KOH or HNO 3 to adjust to the required pH value. Add oxidant before use and mix evenly. Water is the balance. Table 1 Comparative polishing liquids 1 to 2 and polishing liquids 1 to 13 of the present invention Effect Example 1 Using comparative polishing liquids 1 to 2 and polishing liquids 1 to 9 of the present invention, copper (Cu), tantalum (Ta), silicon dioxide (TEOS) and low dielectric material (BD) were processed under the following conditions. Polished. Polishing conditions: The polishing machine is a 12" Reflexion LK machine, the polishing pad is a Fujibo pad, the down pressure is 1.5psi, the rotation speed is polishing disc/polishing head = 113/107rpm, the polishing fluid flow rate is 300ml/min, and the polishing time is 1min . Table 2 Comparison of the removal rates of copper (Cu), tantalum (Ta), silicon dioxide (TEOS) and low dielectric materials (BD) between polishing slurries 1 to 2 and polishing slurries 1 to 9 of the present invention. As can be seen from Table 2, compared with comparative polishing slurries 1 and 2, the polishing slurry of the present invention can obtain a higher removal rate of the barrier layer Ta and silicon dioxide (TEOS), shorten the polishing time, and increase the production capacity. At the same time, by adding Different amounts of siloxane surfactants control the removal rate of low-dielectric material BD to a lower level than TEOS, which is beneficial to controlling the polishing process of pattern wafers and the remaining thickness of BD after polishing, and ensuring the surface uniformity of the wafer. Moreover, by adding different amounts of siloxane surfactants, the removal rate of the dielectric material BD can be adjusted without affecting the removal rate of the barrier layer and silicon dioxide (TEOS) to meet the technical requirements under different process conditions. . Effect Example 2 Comparative polishing liquid 2 and polishing liquids 1 to 3 of the present invention were used to polish a patterned copper wafer according to the following conditions. The graphics wafer is a commercially available 12-inch Sematech754 graphics wafer. The film layer material from top to bottom is copper/tantalum/tantalum nitride/TEOS/BD. The polishing process is divided into three steps. The first step is removed with a commercially available copper polishing solution. For most of the copper, in the second step, use a commercially available copper polishing slurry to remove the remaining copper. In the third step, use the barrier layer polishing slurry of the present invention to remove the barrier layer (tantalum/tantalum nitride), silicon dioxide TEOS, and part of the BD. Remove and stop on the BD layer. Barrier layer polishing liquid polishing conditions: The polishing machine is a 12” Reflexion LK machine, the polishing pad is a Fujibo pad, the down pressure is 1.5psi, the rotation speed is polishing disc/polishing head = 113/107rpm, and the polishing liquid flow rate is 300ml/min. The polishing time is 70 s. Table 3 Comparison of correction capabilities of polishing liquid 2 and polishing liquid 1~3 of the present invention after polishing copper wafers with patterns Among them, the dish-shaped depression is the dish-shaped depression on the metal pad before the barrier layer is polished; the dielectric layer erosion is on the dense line area (50% copper/50% dielectric layer) where the barrier layer line width is 0.18 microns and the density is 50%. dielectric layer erosion, Δ(Å) refers to the correction ability value after polishing. As can be seen from Table 3, compared with the comparative polishing liquid 2, the polishing liquid of the present invention can better correct the dish-shaped depression and erosion produced on the wafer in the previous process (after copper polishing) because it suppresses the removal rate of BD. , a better wafer appearance was obtained. Effect Example 3 A patterned copper wafer was polished using Comparative Polishing Liquid 1 and Polishing Liquid 1 according to the following conditions. The graphics wafer is a commercially available 12-inch Sematech754 graphics wafer. The film layer material from top to bottom is copper/tantalum/tantalum nitride/TEOS/BD. The polishing process is divided into three steps. The first step is removed with a commercially available copper polishing solution. For most of the copper, in the second step, use a commercially available copper polishing slurry to remove the remaining copper. In the third step, use the barrier layer polishing slurry of the present invention to remove the barrier layer (tantalum/tantalum nitride), silicon dioxide TEOS, and part of the BD. Remove and stop on the BD layer. Figures 1 and 2 use SEM images comparing the surface morphology of the Sematech754 patterned wafer after polishing with Polishing Liquid 1 and Polishing Liquid 1 respectively. Figures 3 and 4 respectively compare the surface morphology of Sematech 754 patterned wafers with polishing liquid 1 and polishing liquid 1 after immersion for 30 minutes. It can be seen from the comparison that the polishing liquid of the present invention effectively inhibits metal corrosion, especially the copper wire area is well protected. The surface of the Sematech 754 graphic wafer is still clear and sharp after being polished and impregnated with the polishing liquid of the present invention. No metal corrosion was found, and no contaminant particles remained. It should be understood that the wt% mentioned in the present invention refers to the weight percentage concentration. The specific embodiments of the present invention have been described in detail above, but they are only used as examples, and the present invention is not limited to the specific embodiments described above. For those skilled in the art, any equivalent modifications and substitutions to the present invention are also within the scope of the present invention. Therefore, all equivalent changes and modifications made without departing from the spirit and scope of the present invention should be included in the scope 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； 圖3為採用對比拋光液1浸漬30分鐘後Sematech754圖形晶片的表面形貌的SEM圖；以及 圖4為採用拋光液1浸漬30分鐘後Sematech754圖形晶片的表面形貌的SEM圖。Figure 1 is an SEM image of the surface morphology of Sematech754 graphic wafer after polishing with comparative polishing liquid 1; Figure 2 is an SEM image of the surface morphology of Sematech754 graphic wafer after polishing with polishing liquid 1; Figure 3 is an SEM image of the surface morphology of Sematech754 graphic wafer after polishing with comparative polishing liquid 1; The SEM image of the surface morphology of the Sematech754 patterned wafer after 30 minutes; and Figure 4 is the SEM image of the surface morphology of the Sematech754 patterned wafer after immersion in polishing liquid 1 for 30 minutes.