1288772 玖、發明說明： 【發明所屬之技術領域】 本發明係有關於鎢之化學機械性拋光法（CMP)，特別係關 糸具有可控制之靜態蝕刻速率之鎢Cmp溶液。鎢CMp研磨漿 係藉由鎢之蝕刻及機械性研磨兩項作用使鎢表面平整化。 在鎢之CMP程序中會有競爭性化學反應發生，其中首要之 化學反應係氧化反應。在氧化過程中，氧㈣係在基材之 表面形成氧化鎢。次要反應係複合反應，在該反應中，複 合劑係將氧化過程中於基材表面所形成之氧化薄膜溶解。 【先前技術】 _由於鎢具有回度之穩定性，故鎢研磨漿必需憑藉強力之 氧化训。基於此，強氧化劑如卣氧化物， 當作嫣研磨浆之氧化劑。舉例而言―等人於美國= 編=，993,686案内揭示了氧化金屬鹽、氧化金屬複合物、 =^屬乳化酸（如：過乙酸及過碘酸）、鐵鹽（如：硝酸鹽）硫 酸鹽、乙二胺四乙酸、擰檬酸鹽、鐵氰化鉀、過氧化氫、 重鉻酸鉀、碘酸鉀、溴酸鉀、三氧化二釩及其他相似化合 物、鋁鹽、鈉鹽、鉀鹽、銨鹽、四級銨鹽、磷鹽及其它含 陽離子鹽類之過氧化物、氯酸鹽、過氯酸鹽、硝酸鹽、i 錳酸鹽、過硫酸鹽及其混合物。同樣地，等人於w〇 99/67056錢中揭示其使用之過氧化氫、鐵氰化钾、重路酸 ::碘酸鉀、溴酸鉀、三氧化二釩、次氯酸、次氯酸鈉、 次氣酸鉀、次氯酸鈣、次氯酸鎂、硝酸鐵及其混合物。此 ㈣化劑如i氧化物’可與基材表面進行化學反應而形成 83530 1288772 =氧：層：之後，於CMP製程中之研磨漿可去除基材表 的物J ’疋氣化鎢。以此方式，CMP法即可去除基材表面 的物質而使基材表面平整化。 子衣面 刻程2。⑽私序中所使用之含礎酸鹽研磨漿可抑制靜態敍 蝕：。雖然以碘酸鹽為基礎之研磨漿可成功地 =除氧化鎢，但會造成基材表面刮傷；⑺需要用以去 *广通當设備，使之符合已建立之環境法規。⑺研磨漿 人拋光設備接觸會造成設備轉成Μ望之黃褐色。 於^时利編號5,958,288案中，Mueller等人提及如硝酸 < s鐵乳化劑’可在鐵含量低於扣⑼卩㈣時，作為促 去除鎢之催化劑。這虺 、、’ 一 T足水又問碭在於鎢之靜態蝕刻乃 有時，靜態I 但於大部分言 此外，靜態I 這些表面缺Pj 而—種常見之副作用。在經CMp程序之後，殘留於基材表 上 < 金屬研磨漿仍會持續蝕刻基材表面 刻對於某些半導體整合方案具有利之結果 例中，減少靜態蝕刻可增進半導體之效能 刻，造成如點蝕及鑰匙孔之類的表面缺陷义公农田谭 會_者地影響半導體元件之最後性質，並且限制其用途（ 八^rumbine等人於美國專利編號6,〇83,419案中揭示其使 含氮之氧化劑以控制靜態蝕刻。但就目前所知，這些化 物對於控制靜態蚀刻之效果有限。就目前之鵠抛光研磨 而言，持續性之需求為快速之鎢去除速率及有限之靜態 刻。此外，亦需要一拋光研磨漿，其可之減少因使用含 酸鹽研磨漿所造成之刮傷、環境污染及外觀問題。 83530 1288772 氧化氫、鐵氰化物、重鉻酸鹽、三氧化二釩、次氯酸、次 氯酸鹽、硝酸鹽、過硫酸鹽、過錳酸鹽、氫氧化物及其組 合物組成之群組中。其它特定之實例包括鐵氰化卸、鐵氯 化鈉、重鉻酸鉀、重鉻酸鈉、次氯酸鈣、次氯酸鉀、次氯 酸鈉、硝酸鉀、硝酸鈉、過錳酸鉀、過錳酸鈉及其組合物 通#這些主要氧化劑之混合物可更為增加去除速率。該 掘光溶液典型含有總量01至12重量百分比之主要氧化劑 (就本說明書而言，所有濃度以重量百分比表示，除非有另 外提及）。當添加此類不穩定之主要氧化劑（如過氧化氫）於 拋光溶液時，通常需要於使用時或使用前加入。較佳之情 況為，該拋光溶液典型含有總量05至10重量百分比之主要 乳，劑。最佳之情況為，該拋光溶液典型含有總量丨至75 重I百分比之主要氧化劑。 =之^兄為’該主要氧化劑含有過氧化氣或一含鐵之 :化制。取佳之情況為，該主要氧化劑 除速率。較佳之二:：度•下，仍可提供快速之鶴去 辨況為，添加0.0005至10重量百分比之硝酸 鐵，可增加鎢去除速率；最佳之情況為 0.001至8重量百分屮、x A 汴乂水宁口有 ”重量百八/ 肖酸鐵。此外，抱光溶液中含有2至 合物會在基材表面形抑制層。該抑制化 。此屏障可有效地對,、： 氧化物溶解之表面薄膜 ^ . 士杬對於大部分使鎢表面平敕化所f之 效虱化劑。除 仏叫卞正化所而艾 “成屏障薄膜之外，次要氧化劑亦具有充 83530 1288772 分之氧化力以氧化鎢。然而，該次要氧化劑對於總共之鶴 氧化反應貝獻不大。但就含高量硝酸鐵成分之實例而言， 較高濃度之次要氧化劑對於鎢之氧化反應具顯著之貢獻。 對於大部分之主要氧化劑而言，次要氧化劑為溴酸鹽 (Β『〇3 )、氣酸鹽（ClOf)或其混合物。但就含鐵主要氧化劑 之溶液而言，該次要氧化劑可為溴酸鹽、氯酸鹽、碘酸鹽 或其混合物。但不幸的是，含碘酸鹽之研磨漿通常有昂貴 之環境處置費用及外觀上變色之缺點。然而，就由硝酸鐵 溶液所誘發之高量暗紅褐色而言，此問題較不嚴重。較佳 之情況為，固態粉末狀化合物，可使添加溴酸鹽、氣酸鹽 及碘酸鹽至拋光溶液及研磨漿更有效率。此類化合物之特 疋貫例包括鹼金屬，如銨、鉀、鈉等；鹼土性金屬，如鎂 或其它鹽類。鹼性鹵化合物較易購得或合成。較佳之情況 為，該固態粉末狀化合物係溴酸鉀（KBr〇3)、氣酸鉀（κα〇^、 碘酸鉀（ΚΙ〇3)或其混合物。基於環境之考量，此類鉀化合 物較納或其它驗土金屬為佳。此外，亦可錢光溶液中加 入氣、溴或碘作為基本成分或其他化合物。該主要氧化劑 即Τ以快速之動力學反應，分別將這些次要氧化劑氧化1 fI孤、氣酸鹽或碘酸鹽；由於此類主要氧化劑缺乏將氟 虱化之氧化能力，故此動力學並不適用於氟β同樣地，於 鎢氧化之過程中，過氯酸鹽、過溴酸鹽及過碘酸鹽會分別 形成氣酸鹽、溴酸鹽及碘酸鹽。 車乂佳之情況為，該拋光溶液具有低於400埃/分鐘之如能 刻速率及至少3_埃/分鐘之去除速率。最佳之情況：怨該 】〇 (修 JL 頁）93044 1288772 拋光溶液具有低於200埃/分鐘的靜態蝕刻速率及至少4000 埃/分鐘的去除速率。控制穩定性所需之次要氧化劑之用量 乃取決於拋光溶液之形式及特定之次要氧化劑。大抵而言 ，金屬拋光溶液中，次要氧化劑之濃度不超過其最大溶解 度。於部分實例中，超過此一濃度將會有固體狀未溶解之 次要氧化劑顆粒殘留於拋光溶液中。未溶解之次要氧化劑 顆粒可能會干擾拋光溶液之拋光及蝕刻能力。 /人要氧化劑之濃度範圍可為一較小但有效之濃度至其於 特定拋光溶液中之溶解度極限。此次要氧化劑之溶解度極 限乃取決於拋光溶液之化學性質。在拋光溶液中，該溶解 度極限範圍可自1.8 wt%至22 wt%。較佳之情況為，該次要 氧化劑濃度範圍自0.0001 wt%至7.5 wt%;最佳之情況為， 該次要氧化劑濃度範圍自0·001以％至5 wt%。 ，相對多量之硝酸鐵(2至7.5wt%)時，氧溶== 情況為含有0.1至5 wt%之次要氧化劑。 、、Μ況而定啟拋光，谷液含有〇至50 Wt%之研磨顆粒，·較 佳之情況為，該拋光溶液含有G錢wt%之研磨顆粒；最佳 ^青況為’該抛光溶液含有_5wt%之研磨顆粒。當該研 广：在時’氧化鶴層即被機械式去除。可被接 磨顆粒實例包括下述：氧化鋁、二 鐵、-备於a山 一虱化一卸、鑽石、氧化 一虱化矽、蛟化矽、四氮化三矽、二 物。較佳之情況為，該研磨卿為急^乳化鈥或其組合 佳又情況為，該研磨顆粒為二 ，取 之平均财4·丨m ③化咬。此外，該研磨顆粒 ……情況為低於25。⑽;最佳之情況為 83530 1288772 .. « ，該平均顆粒大小為低於15〇 nm。 若拋光溶液冲不含研磨顆粒，則較佳之情況為使用一固 疋式《研磨墊。取佳之情況為，不含研磨顆粒之溶液僅使 · 用一聚合物墊，合併使用更為強效之主要氧化劑。 此外，孩拋光溶液視情況而定含有一複合劑以幫助鎢之 去除。當存在時，典型之複合劑為一羧酸，其可將氧化鎢 自基質上除去。舉例而言，可被接受之複合劑包括下述： 丙二酸、乳酸、磺基水楊酸（SSA)、甲酸、乙酸、丙酸、丁 酸、戊酸、己酸、庚酸、辛酸、壬酸及其混合物。典型之鲁 拋光溶液可含有〇至15 wt%之複合劑。最佳之情況為，該拋 光/谷液可含有〇·5至5 wt°/〇之複合劑。某種狀沉下，例如拋光 洛液中不含過氧化氫時，複合劑則不可或缺。 水溶液狀之拋光溶液含有剩餘之水及非必要之雜質。最 佳（情況為，該水為去離子水。其次，該水溶液狀拋光溶 液了於性或驗性pH值下操作。較佳之情況為，該挺光溶 液於酸性PH值下操作。最佳之情況為，該拋光溶液於pH值 _ 低方；6下操作。將次要氧化物混合於拋光溶液後，溶液之pH 值係以傳統之方法測量；調整時，可添加鹼，如氫氧化銨 ;或無機酸，如硝酸。硝酸與硝酸鐵合併使用時，可進一 步促進去除速率。 實例 · 氯酸卸係以不同重量百分比添加至鎢拋光研磨漿中。表j 提供鎢拋光研磨漿之組成。 83530 -12- 12887721288772 发明, INSTRUCTION DESCRIPTION: TECHNICAL FIELD OF THE INVENTION The present invention relates to chemical mechanical polishing (CMP) of tungsten, and more particularly to a tungsten Cmp solution having a controllable static etch rate. The tungsten CMp slurry is flattened by tungsten etching and mechanical grinding. A competitive chemical reaction occurs in the CMP process of tungsten, the first of which is an oxidation reaction. In the oxidation process, oxygen (tetra) forms tungsten oxide on the surface of the substrate. The secondary reaction is a complex reaction in which a complex is dissolved in an oxidized film formed on the surface of a substrate during oxidation. [Prior Art] _Because of the stability of tungsten, tungsten slurry must rely on strong oxidation training. Based on this, a strong oxidizing agent such as cerium oxide is used as an oxidizing agent for the cerium slurry. For example, "Essence in the United States = ed = 993, 686 discloses oxidized metal salts, oxidized metal complexes, = ^ emulsified acids (such as: peracetic acid and periodic acid), iron salts (such as: nitrate) sulfuric acid Salt, ethylenediaminetetraacetic acid, citrate, potassium ferricyanide, hydrogen peroxide, potassium dichromate, potassium iodate, potassium bromate, vanadium trioxide and other similar compounds, aluminum salts, sodium salts, potassium salts , ammonium salts, quaternary ammonium salts, phosphorus salts and other peroxides, chlorates, perchlorates, nitrates, i manganates, persulfates and mixtures thereof containing cationic salts. Similarly, et al. disclose the use of hydrogen peroxide, potassium ferricyanide, and heavy acid in the currency of w〇99/67056: potassium iodate, potassium bromate, vanadium trioxide, hypochlorous acid, sodium hypochlorite, secondary gas Potassium acid, calcium hypochlorite, magnesium hypochlorite, iron nitrate and mixtures thereof. The (4) agent such as i oxide can be chemically reacted with the surface of the substrate to form 83530 1288772 = oxygen: layer: Thereafter, the slurry in the CMP process can remove the material J 疋 疋 tungsten from the substrate. In this way, the CMP method removes the surface of the substrate and planarizes the surface of the substrate. The child's face is engraved 2. (10) The base acid slurry used in the private sequence can suppress static etch: Although the iodate-based slurry can successfully = remove tungsten oxide, it will cause scratches on the surface of the substrate; (7) it is necessary to use it to comply with established environmental regulations. (7) Grinding slurry The contact of the human polishing equipment will cause the equipment to turn into a yellowish brown color. In the case of No. 5,958,288, Mueller et al. mention that nitric acid <s iron emulsifier' can act as a catalyst for the removal of tungsten when the iron content is lower than that of deuterium (9) 卩 (iv). This 、 , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , After the CMp process, remaining on the substrate surface < metal slurry will continue to etch the surface of the substrate. For some semiconductor integration solutions, the results are reduced. For example, reducing the static etching can enhance the performance of the semiconductor, resulting in Surface defects such as eclipses and keyholes affect the final properties of semiconductor components and limit their use (8 rumbine et al., U.S. Patent No. 6, 〇83,419, which discloses the use of nitrogen. Oxidants are used to control static etching, but as far as is known, these compounds have limited effectiveness in controlling static etching. For current polishing polishing, the need for persistence is a fast tungsten removal rate and limited static engraving. A polishing slurry is required which reduces scratching, environmental contamination and appearance problems caused by the use of the acid-containing slurry. 83530 1288772 Hydrogen peroxide, ferricyanide, dichromate, vanadium trioxide, hypochlorous a group consisting of acids, hypochlorites, nitrates, persulfates, permanganates, hydroxides, and combinations thereof. Other specific examples include Cyanide unloading, iron sodium chloride, potassium dichromate, sodium dichromate, calcium hypochlorite, potassium hypochlorite, sodium hypochlorite, potassium nitrate, sodium nitrate, potassium permanganate, sodium permanganate and combinations thereof# A mixture of these primary oxidants may increase the removal rate more. The light-extracting solution typically contains a total of from 01 to 12 weight percent of the primary oxidant (for the purposes of this specification, all concentrations are expressed in weight percent unless otherwise mentioned). When such an unstable main oxidizing agent (such as hydrogen peroxide) is added to the polishing solution, it is usually required to be added at the time of use or before use. Preferably, the polishing solution typically contains a total amount of 05 to 10% by weight of the main milk. In the best case, the polishing solution typically contains a total amount of 5% to 75% by weight of the main oxidant. = ^ Brother is 'the main oxidant contains peroxidation gas or an iron: chemical system. For the main oxidant removal rate, preferably the second:: degree, the fast crane can still be provided to distinguish the situation, adding 0.0005 to 10% by weight of ferric nitrate can increase the tungsten removal rate. The best case is 0.001 to 8 weight percent 屮, x A 汴乂水宁口 has “weight 八/magnesium sulphate. In addition, the broth solution contains 2 conjugates which will form a layer on the surface of the substrate. This inhibition can be effectively applied to:, the surface film of oxide dissolution. The most effective agent for the flattening of the tungsten surface, in addition to the 仏 卞 卞 化 而 而 而 成 成In addition to the barrier film, the secondary oxidant also has an oxidizing power of 83530 1288772 to oxidize tungsten. However, the secondary oxidant does not contribute much to the total oxidation of the crane, but for the case of a high content of ferric nitrate. Higher concentrations of secondary oxidants contribute significantly to the oxidation of tungsten. For most major oxidants, the secondary oxidant is bromate (Β『〇3), gas salt (ClOf) or mixtures thereof. . However, in the case of a solution containing a primary oxidizing agent of iron, the secondary oxidizing agent may be a bromate, a chlorate, an iodate or a mixture thereof. Unfortunately, iodate-containing slurries often have the disadvantage of expensive environmental disposal costs and discoloration in appearance. However, this problem is less severe in terms of the high amount of dark reddish brown induced by the ferric nitrate solution. Preferably, the solid powdered compound is more efficient in adding bromate, gasate and iodate to the polishing solution and slurry. Specific examples of such compounds include alkali metals such as ammonium, potassium, sodium, and the like; and alkaline earth metals such as magnesium or other salts. Alkaline halogen compounds are relatively readily available or synthetic. Preferably, the solid powdered compound is potassium bromate (KBr〇3), potassium oxychloride (κα〇^, potassium iodate (ΚΙ〇3) or a mixture thereof. Based on environmental considerations, such potassium compounds are more nano or Other soil-checking metals are preferred. In addition, gas, bromine or iodine may be added as a basic component or other compound in the light-light solution. The main oxidant is a rapid kinetic reaction, and these secondary oxidants are respectively oxidized by 1 fI. , gas acid salt or iodate; because such a main oxidizing agent lacks the oxidizing ability to fluorinate, this kinetics is not suitable for fluorine β. Similarly, in the process of tungsten oxidation, perchlorate, perbromic acid The salt and the periodate form a gas salt, a bromate and an iodate, respectively. In the case of the car, the polishing solution has an etch rate of less than 400 angstroms per minute and at least 3 angstroms per minute. Removal rate. Best case: Responsibility: 〇 (Revision JL page) 93044 1288772 Polishing solution has a static etch rate of less than 200 angstroms per minute and a removal rate of at least 4000 angstroms per minute. Secondary required for control stability The amount of oxidant is Depending on the form of the polishing solution and the particular secondary oxidant. In general, the concentration of the secondary oxidant in the metal polishing solution does not exceed its maximum solubility. In some instances, above this concentration there will be a solid undissolved The secondary oxidant particles remain in the polishing solution. The undissolved secondary oxidant particles may interfere with the polishing and etching ability of the polishing solution. / The concentration of the oxidant may be a small but effective concentration to a specific polishing solution. The solubility limit of the oxidizing agent depends on the chemical nature of the polishing solution. In the polishing solution, the solubility limit can range from 1.8 wt% to 22 wt%. Preferably, the secondary oxidant concentration The range is from 0.0001 wt% to 7.5 wt%; the best case is that the secondary oxidant concentration ranges from 0.001 to 5% by weight. When relatively large amounts of ferric nitrate (2 to 7.5 wt%), the oxygen solution == In the case of 0.1 to 5 wt% of the secondary oxidant, and the polishing is carried out, the grain liquid contains 研磨 to 50 Wt% of the abrasive particles, preferably, the polishing solution contains G money wt% of the abrasive particles; the best condition is 'the polishing solution contains _5wt% of the abrasive particles. When the research: at the time 'oxidized crane layer is mechanically removed. Examples of particles that can be etched include The following: alumina, diiron, - prepared in a mountain, a dumpling, diamond, oxidized bismuth, bismuth, bismuth, and bismuth. Preferably, the grinding is In the case of an emergency emulsified hydrazine or a combination thereof, the abrasive granules are two, and the average enthalpy is 4 丨 m 3 bite. In addition, the abrasive granules ... are less than 25. (10); the best case is 83530 1288772 .. « , the average particle size is less than 15 〇 nm. If the polishing solution is etched without abrasive particles, it is preferred to use a solid-state "polishing pad". Preferably, the solution containing no abrasive particles only uses a polymer mat to combine the more potent primary oxidants. In addition, the baby polishing solution optionally contains a compounding agent to aid in the removal of tungsten. When present, a typical complexing agent is a monocarboxylic acid which removes tungsten oxide from the substrate. For example, acceptable complexing agents include the following: malonic acid, lactic acid, sulfosalicylic acid (SSA), formic acid, acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, heptanoic acid, octanoic acid, Tannic acid and its mixtures. A typical Lu polishing solution may contain from 15 to 15% by weight of the complexing agent. Most preferably, the polishing/trough liquor may contain a complexing agent of 至5 to 5 wt°/〇. When a certain form sinks, for example, when the polishing solution contains no hydrogen peroxide, the compounding agent is indispensable. The aqueous solution-like polishing solution contains residual water and non-essential impurities. Most preferably, the water is deionized water. Secondly, the aqueous solution is operated at a neutral or inspective pH. Preferably, the phosphorescent solution is operated at an acidic pH. In the case, the polishing solution is operated at a pH of _low; 6. After mixing the secondary oxide with the polishing solution, the pH of the solution is measured by a conventional method; when adjusting, a base such as ammonium hydroxide may be added. Or a mineral acid such as nitric acid. Nitric acid combined with ferric nitrate can further promote the removal rate.Examples • Chloric acid unloading is added to the tungsten polishing slurry in different weight percentages. Table j provides the composition of the tungsten polishing slurry. 83530 -12- 1288772
過氧化氫 硝酸鐵 丙二酸 乳酸 石夤基水楊酸 4 wt % 〇·〇1 wt % 〇·〇7 wt % 1.5 wt % 〇·〇! wt % 所得之 隨時間 所得研磨槳之pH值以氳氧化銨調整至約3。之後 研磨漿乃藉由CMP進行標準鎢基質之蝕刻及拋光^叫 測量基質厚度。以厚度改變量對蝕刻時間作圖，並量測： 斜率以決定㈣速率。靜態㈣速率之數據如表Η所示。Hydrogen peroxide, ferric acid, malonate, lanthanide, salicylic acid, salicylic acid, 4 wt%, 〇·〇1 wt % 〇·〇7 wt % 1.5 wt % 〇·〇! wt % The obtained pH of the slurry obtained over time is oxidized by hydrazine The ammonium is adjusted to about 3. The slurry is then etched and polished by a standard tungsten substrate by CMP to measure the substrate thickness. The etching time is plotted as the thickness change, and the slope is measured to determine the (four) rate. The static (four) rate data is shown in Table 。.
表II 鎢金屬拖光研磨漿 在pH值為3且含氯酸鉀蝕刻 抑制劑下之蝕刻速率 i態蝕刻速率(埃 ° 340 °·01 200 0·1 126 --- 70__ =之數據顯示’。，。1%氯酸钾研磨桀溶液可顯著減少鎢 月心、、^丨去除速率。此外，增加氯酸鉀可進一步提古、、办 ^靜=刻抑制能力（欲達到2⑽埃纷鐘之靜態飾刻^ 而之乳酉“甲精確量係取決於特定之研磨聚）。舉例而言， 83530 -13- 1288772 相較於較為鹼性之研磨漿溶液，一種使用氯酸鉀之特定酸 性研磨漿浴液需要不同濃度之次要抑制劑以降低靜態蝕刻 速率至200埃/分鐘以下。 添加一種選自由溴酸鹽、氯酸鹽及碘酸鹽組成之群組中 之次要氧化劑可提供一同時具有快速鎢去除率及有限靜態 蚀刻之鎢抛光溶液。此外，該拋光溶液可排除與傳統式含 琪酸鹽研磨漿相關之表面刮傷。最後，含有溴酸鹽、氯酸 鹽或其混合物之拋光溶液可消除與碘酸鹽相關之環境及外 觀問題。 83530 14-Table II Etch Etching Rate of Tungsten Metal Towed Slurry at pH 3 and Potassium Chlorate Etch Inhibitor (A 340 °·01 200 0·1 126 --- 70__ = Data Display '., 1% potassium chlorate grinding sputum solution can significantly reduce the removal rate of tungsten moon and yttrium. In addition, the increase of potassium chlorate can further improve the ancient, and do static = engraving ability (to achieve 2 (10) E. The exact amount of nipple "depends on the specific grinding poly." For example, 83530 -13 - 1288772 A specific acidic slurry bath using potassium chlorate requires different concentrations than a more alkaline slurry solution. a secondary inhibitor to reduce the static etch rate to less than 200 angstroms per minute. Adding a secondary oxidant selected from the group consisting of bromate, chlorate, and iodate provides a simultaneous high tungsten removal rate and A limited static etching tungsten polishing solution. In addition, the polishing solution can eliminate surface scratches associated with conventional chlorate-containing slurry. Finally, a polishing solution containing bromate, chlorate or a mixture thereof can eliminate iodine. Acid-related environmental and external issues 83530 14-