目前，氧化鈰作為磨料應用於淺溝槽隔離(STI)製程拋光研究已有大量報道，如專利201310495424.5報道了一種用於淺溝槽隔離(STI)製程的化學機械拋光(CMP)組合物，組合物以氧化鈰為磨料，拋光要求達到高的氧化矽/氮化矽拋光選擇比；專利200510069987.3公開了一種化學機械拋光漿料及拋光基板的方法，所涉及的拋光薄膜為氧化矽層，該類材料要求拋光液對氧化矽具有高的拋光速率和低的缺陷產生，對氮化矽顯示低的拋光速率，從而達到高的氧化矽/氮化矽拋光選擇比。 氧化鈰的製備一般通過高溫焙燒碳酸鈰前驅體得到，傳統的碳酸鈰製備過程需要以能夠生成碳酸根或碳酸氫根的可溶性鹽作為沉澱劑，如碳酸銨、碳酸氫銨、碳酸鈉、碳酸鉀等。以這些沉澱劑製備碳酸鈰的過程中，不可避免地產生大量廢水，對環境造成污染危害，也增加了企業的生產成本。 本發明提出了一種創新性的碳酸鈰合成方法，以二氧化碳為沉澱劑，沉澱反應過程中不產生氨氮廢水，反應得到碳酸鈰經簡單洗滌後，焙燒得到高純度氧化鈰粉體，經分散處理後，可有效應用於集成電路拋光應用。At present, there are a lot of reports on the application of yttrium oxide as an abrasive in shallow trench isolation (STI) process polishing. For example, patent 201310495424.5 reports a chemical mechanical polishing (CMP) composition for shallow trench isolation (STI) process, combination The ruthenium oxide is used as the abrasive, and the polishing requirement is to achieve a high yttrium oxide/tantalum nitride polishing selection ratio; Patent 200510069987.3 discloses a chemical mechanical polishing slurry and a method for polishing the substrate, wherein the polishing film is a ruthenium oxide layer, and the like The material requires that the polishing solution have a high polishing rate and low defect generation for cerium oxide, and a low polishing rate for cerium nitride, thereby achieving a high yttrium oxide/tantalum nitride polishing selectivity ratio. The preparation of cerium oxide is generally obtained by calcining a cerium carbonate precursor at a high temperature. The conventional cerium carbonate preparation process requires a soluble salt capable of forming carbonate or bicarbonate as a precipitating agent, such as ammonium carbonate, ammonium hydrogencarbonate, sodium carbonate, potassium carbonate. Wait. In the process of preparing cerium carbonate by using these precipitating agents, a large amount of waste water is inevitably generated, which causes pollution harm to the environment and increases the production cost of the enterprise. The invention provides an innovative method for synthesizing strontium carbonate, wherein carbon dioxide is used as a precipitating agent, and ammonia nitrogen wastewater is not generated during the precipitation reaction, and the reaction is obtained by simply washing the cerium carbonate, and then calcining to obtain high-purity cerium oxide powder, after being dispersed. It can be effectively applied to integrated circuit polishing applications.
本發明的目的是提供一種氧化鈰的製備方法，該製備方法包括： 步驟一：通過沉澱法，進一步由晶化反應製備碳酸鈰前驅體； 步驟二：高溫焙燒所述碳酸鈰前驅體製備氧化鈰粉體。 其中，所述步驟一包括： 配製鈰源水溶液，加熱並持續攪拌； 待鈰源水溶液升溫至沉澱反應溫度，以鼓泡方式向鈰源水溶液引入沉澱劑直至沉澱終點； 保溫並持續攪拌上述反應溶液，經進一步的晶化反應制得碳酸鈰前驅體。 在前述的步驟一操作流程中，鈰源水溶液可以為硝酸鈰、氯化鈰、醋酸鈰中一種或幾種水溶液，優選為硝酸鈰、醋酸鈰，鈰源水溶液的摩爾濃度為0.05-1.0M。 在前述的步驟一操作流程中，所述沉澱法使用的沉澱劑為二氧化碳氣體或二氧化碳與其它氣體混合。 在前述的步驟一操作流程中，所述沉澱反應溫度範圍為60-100℃。 在前述的步驟一操作流程中，所述沉澱法的沉澱終點為，持續加入所述的沉澱劑，反應體系中再無新沉澱物析出；沉澱結束後，繼續保溫攪拌1-24小時。且將所得的碳酸鈰沉澱物分離脫水、洗滌、乾燥得到碳酸鈰前驅體。 在前述的步驟二中，對前述碳酸鈰前驅體進行焙燒，焙燒溫度為400-900℃，焙燒時間為0.5-10小時。 優選地，對所制得的氧化鈰晶體進一步經分散處理，所述分散處理過程無特殊限定，可以是機械研磨如球磨、氣流粉碎等，分散過程中可以添加有機分散劑，所述有機分散劑可以為聚丙烯酸及其鹽類。 本發明所製備的氧化鈰可應用於STI拋光領域，可以達到較高的TEOS拋光速率和TEOS/SiN拋光選擇比。An object of the present invention is to provide a method for preparing cerium oxide, which comprises the following steps: Step 1: preparing a cerium carbonate precursor by a crystallization reaction by a precipitation method; Step 2: preparing a cerium oxide precursor by calcining the cerium carbonate precursor at a high temperature Powder. Wherein, the first step comprises: preparing an aqueous solution of lanthanum, heating and stirring continuously; heating the hydrazine aqueous solution to a precipitation reaction temperature, introducing a precipitant into the hydrazine aqueous solution by bubbling until the end of the precipitation; maintaining and continuously stirring the reaction solution The cerium carbonate precursor is obtained by further crystallization reaction. In the foregoing first step, the aqueous solution of the cerium source may be one or more aqueous solutions of cerium nitrate, cerium chloride or cerium acetate, preferably cerium nitrate or cerium acetate, and the molar concentration of the cerium source aqueous solution is 0.05-1.0M. In the foregoing first step of the operation, the precipitating agent used in the precipitation method is carbon dioxide gas or carbon dioxide mixed with other gases. In the foregoing first step of the operation, the precipitation reaction temperature ranges from 60 to 100 °C. In the foregoing step-one operation procedure, the precipitation end point of the precipitation method is that the precipitant is continuously added, and no new precipitate is precipitated in the reaction system; after the precipitation is finished, the mixture is further kept warm for 1-24 hours. The obtained cerium carbonate precipitate is separated, dehydrated, washed, and dried to obtain a cerium carbonate precursor. In the foregoing step two, the cerium carbonate precursor is calcined at a calcination temperature of 400-900 ° C and a calcination time of 0.5-10 hours. Preferably, the prepared cerium oxide crystal is further subjected to a dispersion treatment, and the dispersion treatment process is not particularly limited, and may be mechanical grinding such as ball milling, jet milling, etc., and an organic dispersing agent may be added during the dispersion, the organic dispersing agent It can be polyacrylic acid and its salts. The cerium oxide prepared by the invention can be applied to the field of STI polishing, and can achieve a higher TEOS polishing rate and a TEOS/SiN polishing selection ratio.
下面通過具體實施例進一步闡述本發明的優點，但本發明的保護範圍不僅僅局限於下述實施例。 本發明所用試劑及原料均市售可得。 實施例1 在室溫條件下，首先配製0.05 M硝酸鈰溶液，在100℃攪拌條件下，向上述溶液中鼓泡加入純二氧化碳氣體，同時攪拌混合液，當不再有新的沉澱析出，停止鼓泡，繼續保溫攪拌1小時晶化反應，將所得沉澱物經純水洗滌3次後、過濾得到濾餅烘乾後得到碳酸鈰粉體；所得碳酸鈰粉體進一步在400℃靜態空氣中焙燒10小時，冷卻後得到氧化鈰粉體；通過添加0.01%聚丙烯酸作為分散劑，對所得氧化鈰粉體進行球磨分散處理，通過控制球磨分散時間，得到可應用於STI拋光的氧化鈰磨料。 實施例2 在室溫條件下，首先配製0.5 M醋酸鈰溶液，在60℃攪拌條件下，向上述溶液中鼓泡加入純二氧化碳氣體，同時攪拌混合液，當不再有新的沉澱析出，停止鼓泡，繼續保溫攪拌24小時晶化反應，將所得沉澱物經純水洗滌3次後、過濾得到濾餅烘乾後得到碳酸鈰粉體；所得碳酸鈰粉體進一步在900℃靜態空氣中焙燒0.5小時，冷卻後得到氧化鈰粉體；通過添加聚丙烯酸作為分散劑，對所得氧化鈰粉體進行球磨分散處理，通過控制球磨分散時間，得到可應用於STI拋光的氧化鈰磨料。 實施例3 在室溫條件下，首先配製1.0 M醋酸鈰溶液，在90℃攪拌條件下，向上述溶液中鼓泡加入純二氧化碳氣體，同時攪拌混合液，當不再有新的沉澱析出，停止鼓泡，繼續保溫攪拌24小時晶化反應，將所得沉澱物經純水洗滌3次後、過濾得到濾餅烘乾後得到碳酸鈰粉體；所得碳酸鈰粉體進一步在600℃靜態空氣中焙燒4小時，冷卻後得到氧化鈰粉體；通過添加聚丙烯酸作為分散劑，對所得氧化鈰粉體進行球磨分散處理，通過控制球磨分散時間，得到可應用於STI拋光的氧化鈰磨料。 實施例4 在室溫條件下，首先配製0.5 M醋酸鈰溶液，在90℃攪拌條件下，向上述溶液中鼓泡加入二氧化碳（占50%體積分數）和氮氣（占50%體積分數）混合氣體，同時攪拌混合液，當不再有新的沉澱析出，停止鼓泡，繼續保溫攪拌24小時晶化反應，將所得沉澱物經純水洗滌3次後、過濾得到濾餅烘乾後得到碳酸鈰粉體；所得碳酸鈰粉體進一步在700℃靜態空氣中焙燒3小時，冷卻後得到氧化鈰粉體；通過添加聚丙烯酸作為分散劑，對所得氧化鈰粉體進行球磨分散處理，通過控制球磨分散時間，得到可應用於STI拋光的氧化鈰磨料。 對比實施例 在室溫條件下，首先配製0.5 M醋酸鈰溶液，在60℃攪拌條件下，向上述溶液中鼓泡加入純二氧化碳氣體，同時攪拌混合液，當不再有新的沉澱析出，停止鼓泡，將所得沉澱物經純水洗滌3次後、過濾得到濾餅烘乾後得到碳酸鈰粉體；所得碳酸鈰粉體進一步在900℃靜態空氣中焙燒0.5小時，冷卻後得到氧化鈰粉體；通過添加聚丙烯酸作為分散劑，對所得氧化鈰粉體進行球磨分散處理，通過控制球磨分散時間，得到可應用於STI拋光的氧化鈰磨料。 實施例效果 分別用上述對比例和實施例中1-4製備得到的氧化鈰為磨料，通過添加0.5%含量的PAA（分子量為4000），配製氧化鈰固含量為0.5%，pH為5.0的拋光液漿料，並測試上述實施例對應拋光液的拋光速率和拋光選擇比。 分別用上述對比例和實施例中1-4配製的拋光液對空白晶片進行拋光，拋光條件相同，拋光參數如下：Logitech拋光墊，向下壓力3psi，轉盤轉速/拋光頭轉速=60/80rpm，拋光時間60s，化學機械拋漿料流速100mL/min。拋光所用晶圓切片均由市售（例如美國SVTC公司生產的）8英寸鍍膜晶圓切片而成。拋光所用的金屬薄膜晶圓切片上金屬薄膜層厚度由NAPSON公司生產的RT-7O/RG-7B測試儀測得，TEOS和SiN的薄膜厚度由TEOS NANO Matrics公司生產的RT-7O/RG-7B測試儀測得。用拋光前後測得的厚度差值除以拋光耗用時間即得金屬薄膜去除速率，拋光時間為1分鐘。拋光後TEOS表面缺陷通過光學顯微鏡100倍放大下觀察。 表1為拋光測試結果，結果表明，所合成氧化鈰磨料可以達到較高的TEOS拋光速率和TEOS/SiN拋光選擇比，所製備的氧化鈰具有良好的STI拋光應用特性。 表1 本發明的化學機械拋光液對比例和實施例拋光效果
應當理解的是，本發明所述wt%均指的是質量百分含量。 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 advantages of the present invention are further illustrated by the following specific examples, but the scope of the present invention is not limited only to the following examples. The reagents and starting materials used in the present invention are commercially available. Example 1 Under the conditions of room temperature, a 0.05 M cerium nitrate solution was first prepared, and under the stirring condition of 100 ° C, pure carbon dioxide gas was bubbled into the above solution while stirring the mixture, and when no new precipitate was precipitated, the mixture was stopped. Bubbling, stirring was continued for 1 hour, and the resulting precipitate was washed 3 times with pure water, and filtered to obtain a cake of cerium carbonate. The obtained cerium carbonate powder was further calcined in static air at 400 ° C. After 10 hours, the cerium oxide powder was obtained by cooling; the obtained cerium oxide powder was subjected to ball-milling dispersion treatment by adding 0.01% polyacrylic acid as a dispersing agent, and the cerium oxide abrasive which can be applied to STI polishing was obtained by controlling the ball milling dispersion time. Example 2 Under the conditions of room temperature, a 0.5 M lanthanum acetate solution was first prepared, and under the stirring condition of 60 ° C, pure carbon dioxide gas was bubbled into the above solution while stirring the mixture, and when no new precipitate was precipitated, the mixture was stopped. Bubbling, continue to heat and stir for 24 hours, and the resulting precipitate was washed 3 times with pure water, and filtered to obtain a cake of cerium carbonate. The obtained cerium carbonate powder was further calcined in static air at 900 ° C. After 0.5 hours, the cerium oxide powder was obtained by cooling; the obtained cerium oxide powder was subjected to ball-milling dispersion treatment by adding polyacrylic acid as a dispersing agent, and the cerium oxide abrasive which can be applied to STI polishing was obtained by controlling the ball milling dispersion time. Example 3 Under the conditions of room temperature, a 1.0 M cesium acetate solution was first prepared, and under the stirring condition of 90 ° C, pure carbon dioxide gas was bubbled into the above solution while stirring the mixture, and when no new precipitate was precipitated, the mixture was stopped. Bubbling, continue to heat and stir for 24 hours, and the resulting precipitate was washed 3 times with pure water, and filtered to obtain a cake of cerium carbonate. The obtained cerium carbonate powder was further calcined in static air at 600 ° C. After 4 hours, the cerium oxide powder was obtained by cooling; the obtained cerium oxide powder was subjected to ball-milling dispersion treatment by adding polyacrylic acid as a dispersing agent, and the cerium oxide abrasive which can be applied to STI polishing was obtained by controlling the ball milling dispersion time. Example 4 At room temperature, a 0.5 M cesium acetate solution was first prepared, and a mixture of carbon dioxide (50% by volume) and nitrogen (50% by volume) was bubbled into the solution under stirring at 90 ° C. While stirring the mixture, when no new precipitates are formed, the bubbling is stopped, and the crystallization reaction is continued for 24 hours, and the obtained precipitate is washed 3 times with pure water, and filtered to obtain a cerium carbonate. The powder; the obtained cerium carbonate powder is further calcined in static air at 700 ° C for 3 hours, and cooled to obtain cerium oxide powder; by adding polyacrylic acid as a dispersing agent, the obtained cerium oxide powder is subjected to ball milling and dispersion treatment, and dispersed by controlling ball milling. Time, a cerium oxide abrasive that can be applied to STI polishing is obtained. Comparative Example At room temperature, a 0.5 M lanthanum acetate solution was first prepared, and under the stirring condition of 60 ° C, pure carbon dioxide gas was bubbled into the above solution while stirring the mixture, and when no new precipitate was precipitated, the mixture was stopped. After bubbling, the obtained precipitate was washed 3 times with pure water, and filtered to obtain a cerium carbonate powder after drying. The obtained cerium carbonate powder was further calcined in static air at 900 ° C for 0.5 hour, and cooled to obtain cerium oxide powder. The obtained cerium oxide powder is subjected to ball-milling dispersion treatment by adding polyacrylic acid as a dispersing agent, and the cerium oxide abrasive which can be applied to STI polishing is obtained by controlling the ball milling dispersion time. EXAMPLES Effect The cerium oxide prepared in the above Comparative Examples and Examples 1-4 was used as an abrasive, and a cerium oxide content of 0.5% and a pH of 5.0 was prepared by adding a 0.5% PAA (molecular weight of 4000). The liquid slurry was tested, and the polishing rate and polishing selection ratio of the polishing liquid corresponding to the above examples were tested. The blank wafers were polished with the polishing solutions prepared in the above Comparative Examples and Examples 1-4, respectively, and the polishing conditions were the same. The polishing parameters were as follows: Logitech polishing pad, downward pressure 3 psi, turntable rotation speed / polishing head rotation speed = 60/80 rpm, The polishing time was 60 s, and the chemical mechanical polishing slurry flow rate was 100 mL/min. The wafer slices used for polishing are all sliced from commercially available (for example, SVTC, USA) 8-inch coated wafers. The thickness of the metal film on the metal film wafers used for polishing was measured by the NTPSON RT-7O/RG-7B tester. The film thickness of TEOS and SiN was RT-7O/RG-7B produced by TEOS NANO Matrics. Tested by the tester. The metal film removal rate was obtained by dividing the difference in thickness measured before and after polishing by the polishing time, and the polishing time was 1 minute. TEOS surface defects after polishing were observed under an optical microscope at 100 magnification. Table 1 shows the results of the polishing test. The results show that the synthesized cerium oxide abrasive can achieve higher TEOS polishing rate and TEOS/SiN polishing selectivity. The prepared cerium oxide has good STI polishing application characteristics. Table 1 Comparative Example and Polishing Effect of Chemical Mechanical Polishing Liquid of the Present Invention It should be understood that the wt% of the present invention refers to the mass 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.