419736419736
本發明是有關於一種化學機械研磨法，且特別是有關 於一種藉由控制研磨製程之pH值，以改善銅化學機械研磨 製程之可靠度的方法。 銅製程已經逐漸成為鑲嵌結構之内連線結構之重要製 程’此製程之特點主要是在介電層定出鑲嵌^構後，再將 金屬銅層覆蓋於介電層上’並且將鑲嵌結構填滿。之後， 再利用化學機械研磨法，將位在介電層上之多餘銅層研磨 去除’元成一鑲嵌狀的鋼内連線。目前’銅的研磨步驟主 要是於相同的pH值環境下’利用化學機械進行研磨。不 過’由於化學機械研磨過程中會有些許副產物會殘留在研 磨墊表面’且隨化學機械研磨機所處理的晶圓片數增加， 殘留於研磨墊表面之副產物將會增加，因而使得化學機械 研磨機之研磨速率不一致’甚至會隨處理*的晶圓片數而顯 著地降低。 有鑒於習知銅化學機械研磨製程之缺點，故本發明之 特徵乃在於揭示一種改善銅化學機械研磨製程之可^度的 方法。其中’研磨處理步驟前’先將晶圓浸泡在鹼液内可 使铜表面產生部分氧化反應，然後再進行化學機械研磨， 將可縮短研磨的反應時間’並且可穩定研磨之速率。此 外’化學機械研磨後所產生的副產物’可輕易地利用酸液 清除。因此，藉由控制銅化學機械研磨製程中之各個步驟 的pH值’便可降低研磨所需的反應時間以及避免副產物殘 留於研磨塾上，穩定每一片晶圓之銅研磨速率。 本發明乃揭示一種改善銅化學機械研磨製程之可靠度The present invention relates to a chemical mechanical polishing method, and more particularly, to a method for improving the reliability of a copper chemical mechanical polishing process by controlling the pH value of the polishing process. The copper process has gradually become an important process for the interconnection structure of the damascene structure. The characteristics of this process are mainly that after the damascene structure of the dielectric layer is determined, the metal copper layer is covered on the dielectric layer. full. After that, the chemical mechanical polishing method is used to grind and remove the excess copper layer on the dielectric layer to form an inlaid steel interconnect. At present, "the grinding step of copper is mainly carried out under the same pH environment" by chemical mechanical grinding. However, 'because some by-products will remain on the surface of the polishing pad during the chemical mechanical polishing process' and as the number of wafers processed by the chemical mechanical polishing machine increases, the by-products remaining on the surface of the polishing pad will increase. The inconsistent polishing rate of mechanical grinders can even decrease significantly with the number of wafers processed *. In view of the shortcomings of the conventional copper chemical mechanical polishing process, the present invention is characterized by revealing a method for improving the reliability of the copper chemical mechanical polishing process. Among them, “before the grinding process step”, immersing the wafer in an alkali solution can cause a partial oxidation reaction on the copper surface, and then performing chemical mechanical polishing, which can shorten the polishing reaction time and stabilize the polishing rate. In addition, the 'by-products produced after chemical mechanical milling' can be easily removed with an acid solution. Therefore, by controlling the pH value of each step in the copper chemical mechanical polishing process, the reaction time required for polishing can be reduced and by-products can not be left on the polishing pad, and the copper polishing rate of each wafer can be stabilized. The present invention is to improve the reliability of a copper chemical mechanical polishing process.
第4頁 4 ^736 五、發明說明（2) 的方法’其步驟包括：（a)提供一表面覆蓋有一銅層之晶 圓；（b)利用驗液處理該晶圓，使晶圓表面之銅層暴露於 鹼性環境下，並且使部分銅層表面被氧化；（c)利用中性 的去離子水沖洗經過鹼液處理過的該晶圓，去除殘留於該 晶圓表面之鹼液；（d)利用化學機械研磨法研磨表面已經 產生部分氧化反應的該銅層；（e)利用酸性的溶液清洗該 銅層表面以及化學機械研磨步驟中所使用的化學機械研磨 機之研磨墊，將研磨時所產生的副產物清除；以及（f)利 用中性的去離子水將殘留於該晶圓表面以及該研磨墊表面 之酸液清除。 如上所述之方法’其中步驟（b)之鹼液的處理方式是 將該晶圓浸泡在鹼液内，或者由該化學機械研磨機直接將 鹼液添加於該晶圓之銅層表面，且該鹼液之pH值範圍為8 〜1 0。另外’步驟（e )中所使用的酸液乃直接被滴在該化 學機械研磨機之研磨墊上’而酸液之pH值範圍為1〜6。此 外，在步驟（f)結束後’更可包括一步驟（g)，重複施行步 驟（a)〜（f ) ’進行下一片晶圓之研磨處理。 為使本發明之特徵更清楚可見，玆將以根據本發明之 較佳實施例’並配合對應圖式，詳細說明如下。 圖式之簡單說明： 第1圖是流程圖’其顯示的是根據本發明用以改善銅 化學機械研磨製程之可靠度的方法。 實施例： 本實施例乃依據第1圖所示之流程，對位在晶圓表面Page 4 ^ 736 V. Description of the invention (2) Method 'The steps include: (a) providing a wafer with a copper layer on its surface; (b) treating the wafer with a test solution to The copper layer is exposed to an alkaline environment, and part of the surface of the copper layer is oxidized; (c) the wafer treated with the alkaline solution is washed with neutral deionized water to remove the alkaline solution remaining on the surface of the wafer; (D) using chemical mechanical polishing to polish the copper layer on which the surface has undergone a partial oxidation reaction; (e) using an acidic solution to clean the surface of the copper layer and the polishing pad of the chemical mechanical polishing machine used in the chemical mechanical polishing step, Removing by-products generated during polishing; and (f) removing the acid solution remaining on the wafer surface and the polishing pad surface with neutral deionized water. The method as described above, wherein the processing method of the lye in step (b) is to soak the wafer in the lye, or directly add the lye to the surface of the copper layer of the wafer by the chemical mechanical polishing machine, and The pH of the lye ranges from 8 to 10. In addition, the acid solution used in the step (e) is directly dropped on the polishing pad of the chemical mechanical polishing machine ', and the pH value of the acid solution ranges from 1 to 6. In addition, after the step (f) is completed, it may further include a step (g), and the steps (a) to (f) are repeated to perform the polishing process for the next wafer. In order to make the features of the present invention more clearly visible, detailed descriptions are given below with reference to the preferred embodiments according to the present invention and corresponding drawings. Brief description of the drawings: Fig. 1 is a flowchart 'showing a method for improving the reliability of a copper chemical mechanical polishing process according to the present invention. Example: This example is based on the process shown in Figure 1, and is aligned on the wafer surface.
4115b 7 a〇: 419736 五、發明說明（3) 之銅層進行化學機械研磨步驟。 首先，步驟100乃先提供一表面覆蓋銅層之晶圓。其 次，進行步驟110之處理程序，利用鹼液處理此表面覆蓋 有銅層之晶圓’使得晶圓表面之銅層暴露於驗性環境下， 並使部分銅層表面被氧化。其中，步驟110卡所使用的鹼 液，例如可為氫氧化鉀，其pH值範圍為8〜14 ;而鹼液的 處理方式則可將晶圓直接浸泡在鹼液内，維持一段適當時 間’或者由該化學機械研磨機直接將鹼液添加於該晶圓之 鋼層表面’使得部分銅層表面被氧化成氧化銅。 然後’繼續進行步驟1 2 0之處理程序，利用中性的去 離子水沖洗經過鹼液處理過的晶圓，去除殘留於晶圓表面 之驗液。接著’進行步驟130，利用化學機械研磨法，研 磨表面已經產生部分氧化銅之銅層。化學機械研磨步驟完 成後’進行步驟1 4 0 ’利用p Η範圍1〜7之酸性溶液，例如 檸檬酸’清除在步驟13〇中’殘留於銅層表面以及研磨墊 表面之副產物’避免該些殘留的副產物降低銅化學機械研 磨製程之速率，並且可降低銅層表面被副產物刮傷而受 損。 最後，進行步驟1 5 0 ’利用中性的去離子水將殘留於 a曰圓表面以及研磨塾表面之酸液清除後，便可再進行下一 步驟160，重複如上所述之步驟1〇〇〜15()，繼續下一片晶 圓之銅化學機械研磨製程。 利用如上所述之方法，藉由控制銅化學機械研磨步驟 時之pH值，先利用鹼液處理表面，然後再進行化學機械研4115b 7 a0: 419736 V. Description of the invention (3) The copper layer is subjected to a chemical mechanical polishing step. First, step 100 is to provide a wafer with a copper layer on the surface. Secondly, the processing procedure of step 110 is performed, and the wafer covered with the copper layer on the surface is treated with an alkali solution so that the copper layer on the wafer surface is exposed to the test environment, and part of the copper layer surface is oxidized. Among them, the alkaline solution used in step 110 can be potassium hydroxide, for example, and its pH value ranges from 8 to 14; and the processing method of the alkaline solution can directly immerse the wafer in the alkaline solution for a proper period of time ' Alternatively, an alkaline solution is directly added to the surface of the steel layer of the wafer by the chemical mechanical polishing machine, so that part of the surface of the copper layer is oxidized to copper oxide. Then, the process of step 120 is continued, and the wafer treated with the alkaline solution is rinsed with neutral deionized water to remove the test solution remaining on the wafer surface. Next, step 130 is performed, using a chemical mechanical polishing method, to grind a copper layer on the surface where copper oxide has been partially formed. After the chemical-mechanical polishing step is completed, 'proceed to step 1 4 0' use an acidic solution in the range of p Η 1 to 7, such as citric acid 'to remove in step 13' by-products remaining on the surface of the copper layer and the surface of the polishing pad ' These residual by-products reduce the rate of the copper chemical mechanical polishing process, and can reduce the surface of the copper layer being scratched and damaged by the by-products. Finally, proceed to step 150. After neutralizing the acid solution remaining on the a-round surface and the surface of the grinding mill with neutral deionized water, proceed to the next step 160, and repeat the step 10 as described above. ~ 15 (), continue the copper chemical mechanical polishing process for the next wafer. Using the method described above, by controlling the pH value during the copper chemical mechanical polishing step, the surface is first treated with an alkali solution, and then the chemical mechanical research is performed.
第6頁 419736 五、發明說明（4) 磨處理，接著再以酸液將殘留於銅層 之副產物清除掉，便可有效地避免殘 學機械研磨製程之速率，使得每一片 研磨時之研磨速率均相當一致，並且 產物刮傷而受損。 雖然本發明已以較佳實施例揭露 限定本發明’任何熟習此技藝者，在 和範圍内’所作之各種更動與潤飾均 内’因此本發明之專利保護範圍當視 所界定者為準。 表面以及 留的副產 晶圓在進 可降低銅 如上，然 不脫離本 落在本發 後附之申 研磨塾表面 物降低銅化 行化學機械 線表面被副 其並非用以 發明之精神 明之範圍 請專利範圍Page 6 419736 V. Description of the invention (4) Grinding treatment, and then removing the by-products remaining in the copper layer with an acid solution, can effectively avoid the rate of residual mechanical grinding process, so that each piece is ground during grinding The rates are quite consistent and the product is scratched and damaged. Although the present invention has been disclosed in a preferred embodiment, the invention is limited to ‘anyone skilled in the art’ is within the scope and scope of the various changes and retouches ’. Therefore, the scope of patent protection of the present invention shall be deemed to be defined. The surface and the remaining by-product wafers can reduce the copper as above, but do not depart from the grinding and surface materials attached to this post to reduce the surface of the chemical mechanical line of the copperization line. It is not the scope of the spirit of invention Patent scope