1311782 (1) 玖、發明說明 【發明所屬之技術領域】 本發明是關於電费加工（plasma processing)，尤指 關於平行平板型RIE方式的電漿蝕刻方法及電漿處理裝 置。 【先前技術】 以往，半導體裝置或FPD ( Flat Panel Display )之製 造步驟的蝕刻加工中，多使用平行平板型電漿蝕刻裝置。 平行平板型電漿蝕刻裝置，乃在處理容器或反應室內，將 上部電極和下部電極平行配置，在下部電極上載置被處理 基板（半導體晶圓、剝離基板等），在下部電極及上部電 極之至少一方，介由整合器施加高頻電壓。藉由因該高頻 電壓而形成於兩電極間的電場，得以加速電子，藉由電子 和處理氣體分子的衝突電離，得以產生電漿，藉由電漿所 生成的自由基或離子，得以蝕刻基板表面的膜。尤其，在 平行平板型的RIE ( Reactive Ion Etching)方式中，電獎 中的離子因形成於基板表面附近之離子層（ion sheath) 的電場而加速’並垂直入射至基板表面，藉此方式，亦可 進行方向性優良的異向性蝕刻。大體上，該方式是採用陰 極耦合’將上部電極接地’對下部電極施加電漿激發用高 頻（參考例如專利文獻1 )。 [專利文獻1]日本特開2000— 12531號公報 1311782 (2) 【發明內容】 [發明所欲解決之課題] 然而，習知平行平板型RIE電漿蝕刻裝置，應用在較 大的晶板尺寸時，尤指大口徑（例如3 00mm )晶圓、或 FPD基板的蝕刻加工中，蝕刻均勻性或蝕刻能力等方面會 產生界限。具體而言，在鋁、鈦、含鈦金屬類的蝕刻中， 要求低壓下的高密度電漿，故必須提高RF功率。然而， 提高RF功率時，會產生電漿集中於基板中心部附近，導 致電漿密度分布之均勻性或蝕刻均勻性降低的問題。再 者，鋁合金、ITO (銦錫氧化物）類的蝕刻或氧化矽膜 (Si02 )的蝕刻中，無法獲得充分的蝕刻速度，選擇性也 不佳。由上述得知，這些被蝕刻材，逐漸採用有利於高密 度電漿之生成的感應性耦合電漿蝕刻裝置（ICP )。 本發明是有鑑於上述問題點而開發者，其目的在於提 供一種蝕刻能力及蝕刻均勻性優良之平行平板型RIE方式 的電漿蝕刻方法及電漿處理裝置。 本發明之其他目的在於提供一種，在双頻重疊施加方 式中得以實現整合電路的小型化及低成本化的電漿處理裝 置。 [解決課題之手段] 爲了達成上述目的，本發明第1電漿蝕刻方法係使用 電漿，用以蝕刻被處理基板上的鋁、鈦或含鈦金屬的膜， 其特徵爲：在可形成真空的處理容器內，與上部電極相對 -5- (3) 1311782 配置的下部電極上，載置上述被處理基板，並且在上述上 部電極和上述下部電極之間，流入含氯原子的氣體、或以 該氯原子爲主成分的蝕刻氣體，並且將第丨高頻和第2高 頻重疊施加於上述下部電極，而該第1高頻具有設定在 10MHz至30MHz範圍內的第1頻率，該第2高頻具有設 定在2MHz至6MHz範圍內的第2頻率。 上述第1電漿蝕刻方法中，於鋁、鈦或含鈦金屬的蝕 刻中，將10MHz至 30MHz的第 1高頻、和 2MHz至 6MHz的第2高頻重疊施加於載置有被處理基板的下部電 極，以此方式，主要藉由第〗高頻，可將電漿密度最適當 化，同時藉由第2高頻，可將自偏壓最適當化，不僅如 此，藉由兩高頻的相互作用，亦可達成電漿密度分布的均 勻性、和自偏壓電壓的均勻性，且可改善蝕刻均勻性。 該電漿蝕刻方法中，欲達成電漿密度分布的均勻化 時，以將第2高頻的RF功率相對於上述第1高頻的RF 功率之比設爲1 / 1 〇以上爲佳，例如，亦可將上述第1高 頻的RF功率設爲1000W以上，將上述第2高頻的RF功 率設爲1 〇 0 W以上。此外，以在氯系蝕刻氣體中混合氬爲 佳。藉由將處理容器內的壓力設爲Torr以下，可進一 步增大偏壓電壓，且可提升蝕刻能力。 本發明第2電漿蝕刻方法係使用電漿’用以蝕刻被處 理基板上的含鋁金屬、或ITO (銦錫氧化物）的膜，其特 徵爲：在可形成真空的處理容器內，與上部電極相對配置 的下部電極上，載置上述被處理基板’並且在上述上部電 -6 - 1311782 (4) 極和上述下部電極之間，流入含氯原子的氣體、或以該氯 原子爲主成分的蝕刻氣體，並且將第1高頻和第2高頻重 疊施加於上述下部電極，而該第1高頻具有設定在 10MHz至30MHz範圍內的第1頻率，該第2高頻具有設 定在2MHz至6MHz範圍內的第2頻率。 上述第2電漿蝕刻方法中，於含鋁金屬或ITO的蝕刻 中，將10MHz至30MHz的第1高頻和2MHz至6MHz的 第2高頻重疊施加於載置有被處理基板的下部電極’以此 方式，主要藉由第1高頻，可將電漿密度最適當化’同時 藉由第2高頻，可將自偏壓最適當化，不僅如此，藉由兩 高頻的相互作用，亦可達成蝕刻速度的提升。再者，蝕刻 均勻性亦可獲得改善。 該電漿蝕刻方法中，爲了達成蝕刻速度的提升，以將 第1高頻的RF功率設爲2000W以上，將第2高頻的RF 功率設在〗〇 〇 W以上爲佳。此外，以在氯系蝕刻氣體中混 合Μ爲佳。 本發明第3電漿蝕刻方法係使用電漿，用以蝕刻被處 理基板上的氧化矽膜，其特徵爲：在可形成真空的處理容 器內，與上部電極相對配置的下部電極上，載置上述被處 理基板，並且在上述上部電極和上述下部電極之間，流入 包含由 CF4、CHF3、CH2F2、C4F8、SF6組成的群組中選 擇至少一種蝕刻氣體，並且將第1高頻和第2高頻重疊施 加於上述下部電極，而該第1高頻具有設定在10MHz至 30MHz範圍內的第1頻率，該第2高頻具有設定在2MHz 1311782 (5) 至6MHz範圍內的第2頻率。 上述第3電漿蝕刻方法中，於氧化矽膜的蝕刻中，將 10MHz至30MHz的第1高頻和2MHz至6MHz的第2高 頻重疊施加於載置有被處理基板的下部電極上’以此方 式，主要藉由第1高頻，可將電漿密度最適當化，同時藉 由第2高頻，可將自偏壓最適當化’不僅如此，藉由兩高 頻的相互作用，亦可達成蝕刻速度的提升。再者，蝕刻均 勻性亦可獲得改善。 該電漿蝕刻方法中，爲了達成蝕刻速度的提升，以將 第1高頻的RF功率設爲2 5 00W以上’將第2高頻的RF 功率設爲2000W以上爲佳。此外，以在蝕刻氣體中添加 H2、02、Ar、He之至少一種爲佳。 本發明之電漿蝕刻方法可適用於大型尺寸的被處理基 板，尤其是平面顯示（Flat Panel Display)用基板。 本發明之電漿處理裝置係在可形成真空的處理容器 內，與上部電極相對配置的下部電極上載置被處理基板， 並且在兩電極間形成高頻電場，同時流入處理氣體，以此 方式，生成上述處理氣體的電漿，而在上述電漿下，對上 述被處理基板實施所期望的電漿處理，其特徵爲：具備： 第1高頻電源，用以將具有第1頻率的第1高頻施加於上 述下部電極；和第1整合電路，爲了進行上述第1高頻電 源側的阻抗和上述下部電極側的負載阻抗之整合，而連接 於上述第1高頻電源和上述下部電極之間；和第2高頻電 源，用以將具有頻率低於上述第I頻率之第2頻率的第2 -8- (6) 1311782 高頻施加於上述下部電極；和第2整合電路，爲了進行上 述第2高頻電源側的阻抗和上述下部電極側的負載阻抗， 而連接於上述第2高頻電源和上述下部電極之間，並且 上述第2整合電路是由輸出段具有線圈的T型電路所構 成，而上述輸出段的線圈乃構成用以遮斷來自上述第1高 頻電源之上述第1高頻的高頻截止濾波器（high cut filter )。 上述電漿處理裝置中，將頻率不同的第1及第2高頻 重疊施加於載置有被處理基板的下部電極之双頻重疊施加 方法中，由最終輸出段具有線圈的T型電構成頻率較低之 第2高頻側的第2整合電路，令其兼具用以進行該線圈匹 配（matching )調整的整合電路 '和用以保護低頻側的第 2高頻電源之高頻截止濾波器（high cut filter )，得以實 現第2整合電路的尺寸及成本的大幅降低。 上述電漿處理裝置中，爲了將構成第2整合電路的原 子數形成最小限度，理想的狀態是，第2整合電路具有： 在第2高頻電源的輸出端子和下部電極之間，與輸出段的 線圈串聯之輸入段的第1電容器；和連接於該第1電容器 與該線圈的連接點和接地電位之間的第2電容器。此時， 進行匹配調整時，以第1及第2電容器的至少一邊是得以 進行電容之可變調整的可變電容器爲佳。輸出段的線圈， 爲了保證具有高頻遮斷功能，以具有1 00歐姆以上的阻抗 爲佳。 又，上述電漿處理裝置中，爲了將電漿密度的分布特 -9- 1311782 (7) 性最適當化，理想的狀態是’第1頻率設定在1 ΟΜΗζ至 30MHz的範圍內，第2頻率設定在2MHz至6MHz的範圍 內。上部電極亦可典型地連接於接地電位。上述電漿處理 裝置所使用的處理氣體是含Cl2、BC13、HC1、SF6、 CF4、CHF3、CH2、F2 ' 〇2、N2、H2、Ar、He 中的一種之 單氣體、或含兩種以上的混合氣體。 [發明的效果] 根據本發明的電漿蝕刻方法及電漿處理裝置，藉由具 有上述之構成和作用，得以進行蝕刻能力及蝕刻均勻性優 良之平行平板型RIE方式的電漿蝕刻。再者，根據本發明 之電漿處理裝置，藉由具有上述之構成和作用，在双頻重 疊施加方式中，得以實現整合電路的小型化及低成本化。 【實施方式】 以下’參佐附圖，說明本發明較合適的實施型態。 第1圖是表示本發明一實施型態之電漿蝕刻裝置重要 部位的構成。該電漿蝕刻裝置是平行平板型RIE電漿蝕刻 裝置的構成’具有例如鋁或不銹鋼等金屬製的真空室（處 理容器）10。真空室10係形成保護接地。 在真空室10內的底面，隔著陶瓷等絕緣板〗2，設有 由例如鋁所構成的支持台14，在該支持台14上設有由例 如鋁構所成的下部電極16。該下部電極16兼具用以載置 被處理基板（例如FPD基板）G的載置台。 -10- (8) 1311782 在下部電極1 6的上方，與該電極1 6平行相對地配置 有上部電極18。在該上部電極18上，形成有用以構成噴 頭（shower head)的多數貫通孔或氣體排出口 I8a。在設 置於上部電極18的背面之氣體導入口 20上，連接有來自 處理氣體供給源22的氣體供給管24。在該氣體供給管24 的中途，設有流量調整器（MFC) 26及開關閥28。 在真空室10的底部設有排氣口 30，在該排氣口 30 上介由排氣管32連接有排氣裝置34。排氣裝置34具有 渦輪分子泵等真空泵，可將真空室10內的電漿空間減壓 至所期望的真空度。在真空室10的側壁，設置基板搬入 出口 （未圖示），而在該基板搬入出口上，介著閘閥 (gate valve )，連接有鄰室的加載互鎖真空室（load-lock chamber)(未圖示）。 該電漿蝕刻裝置中，將下部電極1 6形成電性陰極耦 合配置。上部電極18乃介著真空室10與接地電位連接 (接地）。另一方面，在下部電極16上，分別介著第1 及第2整合器36、38，電性連接有第1及第2高頻電源 40 、 42 。 第1高頻電源40主要是幫助電漿的生成’故理想的 狀態是將具有10MHz至30MHz之頻率（例如13.56MHz 或27.12MHz)的第1高頻（以下’稱爲「電源 (source )用高頻」。）RFS，以所期望的功率（P〇wer ) 輸出。第1整合器3 6是用以進行高頻電源4 0側的阻抗和 下部電極〗6側的負載阻抗之整合，其具有用以進行匹配 -11 - 1311782 (9) (matching )調整的整合電路44 '和用以保護高頻電源 40 的帶通濾波器（band-pass filter) 46。 整合電路44是由兩個可變電容器48' 50和一個線圈 52所構成的L型電路。更詳言之，在輸入端子（節點 Na )和接地電位之間連接有電容器48，在輸入端子（節 點Na )和輸出端子（節點Ne )之間，串聯線圈52和電容 器50。藉由將兩可變電容器48' 50的電容進行可變調 整，得以使含整合電路44之下部電極1 6側的負載阻抗， 與含帶通濾波器46之第1高頻電源40側的阻抗在外觀上 —致。 帶通濾波器46是將線圈54和電容器56串聯而成的 串聯共振電路。僅選擇性地與電源用高頻RFS附近的高頻 帶域相通。即使來自第2高頻電源42的高頻RFb通過整 合電路44 ’也會被該帶通濾波器46遮斷，不會傳送至第 1高頻電源4 0。 第2高頻電源42主要是幫助自偏壓Vde的調整，故 理想的狀態是將具有 2MHz至 6MHz之頻率（例如 3·2ΜΗζ)的第2高頻（以下’稱爲「電源用高頻」。） RFb’以所期望的功率輸出。第2整合器38是用以進行高 頻電源42側的阻抗和下部電極丨6側的負載阻抗之整合， 是由兩個可變電容器58、60和一個線圈62所構成的T型 電路，且兼具匹配（matching )調整用的整合電路、和用 以保護高頻電源42的濾波電路。 更詳言之’在高頻電源42側之整合器輸入端子和下 -12- 1311782 (10) 部電極16側之整合器輸出端子（節點N。）之間，串聯有 電容器58和線圈62，在電容器58和線圈62的連接點 (節點N b )和接地電位之間’連接有電容器6 0。在該τ 型電路中’最後輸出段的線圈62 ’是以單獨或藉由與接 ；t也俱I]之電容器6 0的組合，構成高頻截止濾波器（h i g h c u t filter ) ’而具有遮斷來自第1高頻電源40之電源用高頻 RFS的功能。爲了保證該高頻遮斷功能’以將線圈62的 阻抗形成1〇〇歐姆以上爲佳。另一方面，藉由將兩可變電 容器58、60的電容進行可變調整，得以使含該整合電路 (5 8、60、62 )之下部電極1 6側的負載阻抗，與第2高 頻電源42側的阻抗在外觀上一致。此外’整合器輸出端 子（節點N e )和下部電極1 6之間的給電線64亦可由饋 電棒構成。 如上所述，本實施型態之電漿蝕刻裝置中，將電源用 高頻RFS和偏壓用高頻RFb重疊施加在下部電極16的双 頻重疊施加方式中’由最後輸出段具有線圈62之三元件 (58、60、62 )的T型電路構成低頻率側的整合器38， 使該線圈62兼具用以保護低頻率側（即偏壓用高頻RFb 側）的高頻電源42的高頻截止濾波器。藉此構成，可實 現整合器38之尺寸及成本的大幅降低。 於該電漿蝕刻裝置中，進行蝕刻時，首先將閘閥形成 開啓的狀態’將加工對象的基板G搬進真空室10內’並 載置於下部電極1 6上。然後，從處理氣體供給源22 ’將 預定的蝕刻氣體以預定流量及流量比導入真空室1〇內’ -13- (11) 1311782 藉由排氣裝置34將真空室10內的壓力形成設定値。再 者，從第1高頻電源40，以預定功率，對下部電極1 6， 施加電源用高頻RFS，大約在此同時，從第2高頻電源 42，以預定功率，施加偏壓用高頻RFS。從噴頭（上部電 極）18噴出的蝕刻氣體在兩電極16、18之間，藉由高頻 放電形成電漿化，藉由因該電漿而生成的自由基或離子， 得以蝕刻基板G的主面。 在此，由第1高頻電源40，施加於下部電極16的電 源用高頻RFS，主要是作用於下部電極1 6和上部電極1 8 之間的高頻放電，進而增強作用於電漿的生成。一般而 言，平行平板型中，施加在兩電極間之高頻的頻率越高的 話，越可提升電漿密度，然而，電極中心部側比電極邊緣 部側更容易變高。又，電源用高頻RFs的功率越高的話， 越可提高賦予電漿的能源，越可提升電漿密度，然而，電 漿容易集中於電極中心部，造成電漿密度分布的均勻性降 低。本實施型態中，如上所述，藉由電源用高頻RF s和偏 壓用高頻RFb的双頻重疊施加方式，得以解決該問題。 由第2高頻電源42，施加於下部電壓16的偏壓用高 頻RFb’會先作用於生成於下部電極16或基板G之負的 自偏壓電壓Vde的大小（絕對値），進而作用於將電漿中 的離子引入基板G的電場強度。一般而言，自偏壓電壓 Vd。在頻率軸上具有極大點，當偏壓用高頻RFb的頻率過· 高（6MHz以上）時，Vde反而會變小，而當偏壓用高頻 RFb的頻率變得過低時’ Vde也會變小。由此觀點來看， -14 - 1311782 (12) 本實施型態中乃將偏壓用高頻RFb設在2MHz至6MHz的 範圍內。 本案發明者，在本實施型態之双頻重疊施加方式的平 行平板型RIE電漿蝕刻裝置中，重複數次實驗且致力於檢 討的結果，發現藉由適當選擇電源用高頻RFS和偏壓用高 頻RFb的頻率、功率、壓力或蝕刻氣體等其他蝕刻條件， 不僅可將自由基基礎（radical base )的化學蝕刻、和離 子基礎（ion base )的物理蝕刻，分別進行獨立控制或最 適當化控制，而且關於特定的被蝕刻材，也可提升電漿密 度分布的均勻性、或獲得與ICP (電感性耦合電漿蝕刻裝 置）匹敵的蝕刻能力。 繼之，說明本發明之電漿蝕刻方法的具體實施例。 [實施例1] 使用第1圖的電漿蝕刻裝置，在鋁（A1 )的蝕刻中， 以電源用高頻RFS ( 13·56ΜΗζ)的功率Ps和偏壓用高頻 RFb ( 3.2MHz)的功率Pb作爲參數，評價電漿密度分布的 均勻性。 設置鋁的配線之多層配線構造中，爲了容易進行絕緣 膜的埋設，期望在下層側，尤其在最下層的鋁配線進行錐 狀0虫刻（taper etching )。因此在 FPD的銘·錐狀触刻 中，得以進行異向性蝕刻’所以以降低壓力’提高電源用 高頻RFS的功率Ps爲佳。 然而，如第4圖至第6圖的比較例1'2、3所示’在 -15- (13) 1311782 沒有施加偏壓用高頻RFb而僅利用電源用高頻RFS的單頻 施加方式中，RFS的功率ps越高，真空室內的壓力越低 時，電漿密度在各位置就變得越高，但是，會發生電極中 心部附近異常突出而變高的不良現象。又，如第4圖所 示，即使電極間隙（GAP )變大，電漿密度的均勻性也會 降低。更詳言之，在21 Omm的電極間隙（GAP )中，將 壓力設爲SmTorr以下，將電源用高頻RFS的功率Ps設在 1000W以上的條件之應用（application)中，欲獲得均勻 性良好的電漿密度分布是很不可能的。 相對於此’双頻重疊施加方式的實施例1中，如第2 圖及第3圖所示，與電源用高頻RFS的功率Ps成比例 地’理想的狀態是藉由以1 / 1 〇以上的比率，選擇偏壓用 高頻RFb的功率P b ’上述條件的應用中亦可獲致大致平 均的電漿密度分布。藉此方式，確認使用第1圖的電漿蝕 刻裝置’對於基板G上的鋁膜，進行蝕刻均勻性優良之 所期望的蝕刻加工。再者，鈦及含鈦金屬皆屬於與鋁相同 種類的被蝕刻材’這些金屬同樣可進行蝕刻均勻性優良之 所期望的蝕刻加工。 此外’第2圖及第4圖的資料，是經由設置於真空室 1 0側壁的螢幕窗（未圖示），藉由目視觀測來評價真空 室內部（尤其是兩電極間）的電漿發光狀態，看到電漿發 光區域集中於一處（通常爲中心部）的現象時，劃上均勻 性不良（X )的記號’看到電漿發光區域大致同樣分布的 現象時’劃上均勻性良好（0 )的記號。另一方面，第3 -16 · (14) 1311782 圖、第5圖及第6圖的資料，是藉由使用網路分析器之電 漿吸收探針（P A P )法，來計測電漿密度分布，作爲電子 密度分布。 又，上述實施例1及比較例1、2中，是使用氯氣C12 (流量3 0 0或2 0 0 s c c m )，作爲蝕刻氣體，然而，如第6 圖的參考例所示，得知在氯氣中，以適當的流量比（理想 的狀態是 Cl2/Ar = 125/75 至 100/100)混合氬（Ar) 的方法，得以改善電漿密度分布的均勻性。 [實施例2] 使用第1圖的電漿蝕刻裝置，在一種鋁合金之鋁·銨 (AINd )的蝕刻中，以偏壓用高頻RFb ( 3.2MHZ )的功 率Pb作爲參數，評價蝕刻速度的大小。就其他主要的蝕 刻條件而言，將電極間隙（GAP )設爲1 40mm、蝕刻氣體 設爲Cl2(流量300sccm)、真空室內壓力設爲5mTorr、 溫度（上部電極（T) /下部電極（B) /真空室側壁 (W) ) = 60/20/60 °C、電源用高頻 RFS( 13.56MHz) 的功率Pb設爲2000W。蝕刻氣體亦可使用BC13等氯系氣 體。 又，被處理基板G是使用550x650尺寸的LCD用剝 離基板，如第8圖所示，以基板上多數的測定點（1至 14)，來測試蝕刻速度，在中心部（7、8 )及中間部 (4、5、1 0、1 1 )，求得平均値，在邊緣部（1、2、3、 6、9、1 2、1 3、1 4 )，求得最大値和最小値。 -17- 1311782 (15) 如第8圖的曲線圖所示，得知偏壓用高頻RFb (3 ·2ΜΗζ )的功率Pb越高的話，鋁.銨的蝕刻速度則越 大，Pb= 1000W以上，可獲得大約2000A/min以上的蝕 刻速度。因此’可確認藉由在鋁合金的蝕刻加工，使用第 1圖的電漿蝕刻裝置’可獲致與ICP (電感性耦合電漿蝕 刻裝置）匹敵之充分的蝕刻能力。又，因爲利用本發明之 双頻重疊施加方式’也可達成電漿密度的均勻化，所以也 可達成蝕刻均勻性的提升。此外，IT◦也是屬於與鋁合金 同種類的被蝕刻材，該合金亦可獲得與對於鋁合金者同樣 的蝕刻能力。 使用第1圖的電漿蝕刻裝置，以矽基板或矽層（Si) 爲基底層之氧化矽膜（Si〇2 )的蝕刻中，以偏壓用高頻 RFb ( 3.2MHz )的功率Pb作爲參數，測試各蝕刻速度及選 擇比。就其他主要的蝕刻條件而言，將電極間隙（GAP ) 設爲140mm、f虫刻氣體設爲CHF3(流量200sccm)、真 空室內壓力設爲5mT〇rr、溫度（上部電極（T) /下部電 極（B ) /真空室側壁（W ) ) = 60 / 20 / 60 °C、電源用 高頻RFs(27.12MHz)的功率Pb設爲2500W。在此，將 電源用高頻RFS的頻率設爲27.12MHz是爲了獲得比 13.56ΜΗΖ更高密度的電漿之故。蝕刻氣體不僅是CHF3, 也可使用 CF4、CH2F2、C4Fs中之任一種或兩種氣體和 H2、Ar的混合氣體等。再者’也可使用SF6、02及希氣 體的混合氣體。 如第 9圖的曲線圖所示’得知偏壓用高頻 RFb -18- (16) 1311782 (3·2ΜΗζ)的功率Pb越高的話’ SiCh的蝕刻速度越大’ P b = 1 〇 〇 0 W以上，可獲得大約1 0 0 0 A / m in以上的蝕刻速 度，同時可獲得約1 0以上的選擇比。如上所述’得以確 認藉由在Si〇2膜的蝕刻加工’使用第1圖的電漿蝕刻裝 置，可獲致與icp (電感性耦合電漿蝕刻裝置）匹敵之充 分的蝕刻能力。又’因爲藉由本發明之双頻重疊施加方 式，亦可達成電漿密度的均勻化，所以亦可獲致蝕刻均勻 性的提升。 上述實施型態之電漿蝕刻裝置（第1圖）的基本型態 亦可適用於其他的電漿處理裝置，例如，可在施行電漿 CVD、電漿氧化、電漿氮化、濺鍍等的各種電漿處理裝置 中變形。此外，本發明之被處理基板並不侷限於FPD基 板，亦可爲半導體晶圓、光遮罩、CD基板、印刷基板 等。 【圖式簡單說明】 第1圖是表示本發明一實施型態之電漿蝕刻裝置的重 要部位構成圖。 第2圖是表示第1實施例中，藉由目視觀察電漿密度 分布特性的評價結果圖。 第3圖是表示第1實施例的電子密度分布特性圖。 第4圖是表示比較例中，藉由目視來觀察電漿密度分 布特性的評價結果圖。 第5圖是表示比較例的電子密度分布特性圖。 -19- (17) 1311782 第6圖是表示比較例的電子密度分布特性圖。 第7圖是表示參考例的電子密度分布特性圖。 第8圖是表示第2實施例之蝕刻速度的偏壓功率依存 性圖。 第9圖是表示第3實施例之蝕刻速度的偏壓功率依存 性圖。 ❿ 主要元件符號說明〕 10真空室（處理容器） 1 6下部電極 1 8 上部電極 22處理氣體供給源 3 4排氣裝置 36第1(電源用）整合器 38第2(偏壓用）整合器 40第1(電源用）高頻電源 4 2第2 (偏壓用）高頻電源 58可變電容器 60可變電容器 6 2 線圈1311782 (1) Field of the Invention The present invention relates to plasma processing, and more particularly to a plasma etching method and a plasma processing apparatus for a parallel plate type RIE method. [Prior Art] Conventionally, in a etching process of a semiconductor device or a manufacturing process of an FPD (Flat Panel Display), a parallel plate type plasma etching device is often used. In the parallel plate type plasma etching apparatus, the upper electrode and the lower electrode are arranged in parallel in the processing container or the reaction chamber, and the substrate to be processed (semiconductor wafer, peeled substrate, etc.) is placed on the lower electrode, and the lower electrode and the upper electrode are placed on the lower electrode. At least one of the high frequency voltages is applied via the integrator. By forming an electric field between the electrodes due to the high-frequency voltage, electrons are accelerated, and plasma is generated by collisional ionization of electrons and processing gas molecules, and is etched by radicals or ions generated by the plasma. a film on the surface of the substrate. In particular, in the RIE (Reactive Ion Etching) method of the parallel plate type, ions in the electric prize are accelerated by the electric field of the ion sheath formed near the surface of the substrate and are incident perpendicularly to the surface of the substrate. Anisotropic etching with excellent directivity can also be performed. In general, this method uses a cathode coupling 'grounding the upper electrode' to apply a high frequency for plasma excitation to the lower electrode (refer to, for example, Patent Document 1). [Patent Document 1] Japanese Laid-Open Patent Publication No. 2000-12531 (Patent Document 1) [2] [Problems to be Solved by the Invention] However, a conventional parallel plate type RIE plasma etching apparatus is applied to a large crystal plate size. In the etching process of a large-diameter (for example, 300 mm) wafer or an FPD substrate, there is a limit in etching uniformity or etching ability. Specifically, in the etching of aluminum, titanium, and titanium-containing metals, high-density plasma at a low pressure is required, so it is necessary to increase the RF power. However, when the RF power is increased, there is a problem that the plasma concentrates in the vicinity of the center portion of the substrate, and the uniformity of the plasma density distribution or the etching uniformity is lowered. Further, in the etching of an aluminum alloy or an ITO (indium tin oxide) or etching of a hafnium oxide film (SiO 2 ), a sufficient etching rate cannot be obtained, and the selectivity is also poor. From the above, it is known that these etched materials are gradually subjected to an inductively coupled plasma etching apparatus (ICP) which is advantageous for the formation of high-density plasma. The present invention has been made in view of the above problems, and an object thereof is to provide a plasma etching method and a plasma processing apparatus of a parallel plate type RIE method which are excellent in etching ability and etching uniformity. Another object of the present invention is to provide a plasma processing apparatus which realizes miniaturization and cost reduction of an integrated circuit in a dual-frequency overlapping application method. [Means for Solving the Problem] In order to achieve the above object, the first plasma etching method of the present invention uses a plasma for etching an aluminum, titanium or titanium-containing metal film on a substrate to be processed, which is characterized in that a vacuum can be formed. In the processing container, the substrate to be processed is placed on the lower electrode disposed opposite to the upper electrode by -5-(3) 1311782, and a gas containing chlorine atoms is introduced between the upper electrode and the lower electrode, or The chlorine gas is an etching gas containing a main component, and the second high frequency and the second high frequency are superimposed on the lower electrode, and the first high frequency has a first frequency set in a range of 10 MHz to 30 MHz. The high frequency has a second frequency set in the range of 2 MHz to 6 MHz. In the first plasma etching method, in the etching of aluminum, titanium, or a titanium-containing metal, a first high frequency of 10 MHz to 30 MHz and a second high frequency of 2 MHz to 6 MHz are superposed on the substrate on which the substrate to be processed is placed. The lower electrode, in this way, can optimize the plasma density mainly by the high frequency, and at the same time, the second high frequency can optimize the self-bias, and not only the two high frequency The interaction can also achieve uniformity of plasma density distribution, uniformity of self-bias voltage, and improvement of etching uniformity. In the plasma etching method, in order to achieve uniformization of the plasma density distribution, it is preferable to set the ratio of the RF power of the second high frequency to the RF power of the first high frequency to be 1 / 1 〇 or more. The RF power of the first high frequency may be 1000 W or more, and the RF power of the second high frequency may be 1 〇 0 W or more. Further, it is preferred to mix argon in a chlorine-based etching gas. By setting the pressure in the processing container to Torr or less, the bias voltage can be further increased and the etching ability can be improved. The second plasma etching method of the present invention uses a plasma 'membrane for etching an aluminum-containing metal or ITO (indium tin oxide) on a substrate to be processed, which is characterized in that in a processing container capable of forming a vacuum, a substrate on which the substrate to be processed is placed on the lower electrode opposed to the upper electrode, and a gas containing a chlorine atom or a chlorine atom is mainly flowed between the upper electrode -6 - 1311782 (4) and the lower electrode. The etching gas of the component is applied to the lower electrode by superposing the first high frequency and the second high frequency, and the first high frequency has a first frequency set in a range of 10 MHz to 30 MHz, and the second high frequency is set at The second frequency in the range of 2 MHz to 6 MHz. In the second plasma etching method, in the etching of the aluminum-containing metal or ITO, the first high frequency of 10 MHz to 30 MHz and the second high frequency of 2 MHz to 6 MHz are superposed on the lower electrode on which the substrate to be processed is placed. In this way, the plasma density can be optimally optimized by the first high frequency, and the self-bias can be optimally optimized by the second high frequency. Moreover, by the interaction of the two high frequencies, An increase in the etching speed can also be achieved. Furthermore, the etching uniformity can also be improved. In the plasma etching method, in order to achieve an increase in the etching rate, it is preferable to set the RF power of the first high frequency to 2000 W or more and the RF power of the second high frequency to be 〇 〇 W or more. Further, it is preferred to mix ruthenium in a chlorine-based etching gas. The third plasma etching method of the present invention uses a plasma for etching a ruthenium oxide film on a substrate to be processed, and is characterized in that a lower electrode disposed opposite to the upper electrode is placed in a processing chamber capable of forming a vacuum The substrate to be processed, and between the upper electrode and the lower electrode, at least one etching gas is selected from the group consisting of CF4, CHF3, CH2F2, C4F8, and SF6, and the first high frequency and the second high are The frequency overlap is applied to the lower electrode, and the first high frequency has a first frequency set in a range of 10 MHz to 30 MHz, and the second high frequency has a second frequency set in a range of 2 MHz 1311782 (5) to 6 MHz. In the third plasma etching method, in the etching of the hafnium oxide film, the first high frequency of 10 MHz to 30 MHz and the second high frequency of 2 MHz to 6 MHz are superimposed on the lower electrode on which the substrate to be processed is placed. In this way, the plasma density can be optimally optimized by the first high frequency, and the self-bias can be optimally optimized by the second high frequency, not only by the interaction of the two high frequencies, but also by the interaction of the two high frequencies. An increase in etching speed can be achieved. Furthermore, the etching uniformity can also be improved. In the plasma etching method, in order to achieve an increase in the etching rate, it is preferable to set the RF power of the first high frequency to 2 500 W or more. The RF power of the second high frequency is preferably 2000 W or more. Further, it is preferred to add at least one of H2, 02, Ar, and He to the etching gas. The plasma etching method of the present invention can be applied to a large-sized substrate to be processed, particularly a substrate for a flat panel display. In the plasma processing apparatus of the present invention, in the processing container capable of forming a vacuum, the substrate to be processed is placed on the lower electrode disposed opposite to the upper electrode, and a high-frequency electric field is formed between the electrodes, and the processing gas is simultaneously introduced. Forming a plasma of the processing gas, and performing a desired plasma treatment on the substrate to be processed under the plasma, comprising: a first high frequency power supply for first having a first frequency a high frequency is applied to the lower electrode; and the first integrated circuit is connected to the first high frequency power source and the lower electrode in order to integrate the impedance on the first high frequency power source side and the load impedance on the lower electrode side And a second high frequency power supply for applying a second -8-(6) 1311782 high frequency having a second frequency lower than the first frequency to the lower electrode; and a second integrated circuit for performing The impedance on the second high-frequency power source side and the load impedance on the lower electrode side are connected between the second high-frequency power source and the lower electrode, and the second integrated circuit is output. The segment has a T-shaped circuit having a coil, and the coil of the output segment constitutes a high cut filter for blocking the first high frequency from the first high frequency power supply. In the above-described plasma processing apparatus, the first and second high-frequency superimposed frequencies having different frequencies are applied to the double-frequency overlapping application method of the lower electrode on which the substrate to be processed is placed, and the T-type electric power having the coil is formed in the final output section. The second integrated circuit on the lower second high frequency side has both an integrated circuit for performing the matching of the coils and a high frequency cut filter for protecting the second high frequency power supply on the low frequency side. (high cut filter), the size and cost of the second integrated circuit can be greatly reduced. In the plasma processing apparatus, in order to minimize the number of atoms constituting the second integrated circuit, it is preferable that the second integrated circuit has: between the output terminal of the second high-frequency power source and the lower electrode, and the output section The first capacitor of the input section in series with the coil; and the second capacitor connected between the connection point of the first capacitor and the coil and the ground potential. In this case, when the matching adjustment is performed, it is preferable that at least one of the first and second capacitors is a variable capacitor that can be variably adjusted in capacitance. The coil of the output section preferably has an impedance of more than 100 ohms in order to ensure a high frequency interrupting function. Further, in the plasma processing apparatus, in order to optimize the distribution of the plasma density, the ideal frequency is that the first frequency is set in the range of 1 ΟΜΗζ to 30 MHz, and the second frequency is set. Set in the range of 2MHz to 6MHz. The upper electrode can also typically be connected to a ground potential. The processing gas used in the plasma processing apparatus is a single gas containing one of Cl2, BC13, HC1, SF6, CF4, CHF3, CH2, F2' 〇2, N2, H2, Ar, He, or two or more types thereof. Mixed gas. [Effects of the Invention] According to the plasma etching method and the plasma processing apparatus of the present invention, the plasma etching of the parallel plate type RIE method in which the etching ability and the etching uniformity are excellent can be performed by the above-described configuration and action. Further, according to the plasma processing apparatus of the present invention, by the above-described configuration and operation, in the dual-frequency overlapping application method, the size and cost of the integrated circuit can be reduced. [Embodiment] Hereinafter, a more appropriate embodiment of the present invention will be described with reference to the accompanying drawings. Fig. 1 is a view showing the configuration of an important portion of a plasma etching apparatus according to an embodiment of the present invention. This plasma etching apparatus is a configuration of a parallel plate type RIE plasma etching apparatus, and has a vacuum chamber (processing container) 10 made of a metal such as aluminum or stainless steel. The vacuum chamber 10 forms a protective ground. On the bottom surface of the vacuum chamber 10, a support table 14 made of, for example, aluminum is provided via an insulating plate 2 such as ceramics, and a lower electrode 16 made of, for example, an aluminum structure is provided on the support table 14. The lower electrode 16 also has a mounting table on which a substrate to be processed (for example, an FPD substrate) G is placed. -10- (8) 1311782 The upper electrode 18 is disposed above the lower electrode 16 in parallel with the electrode 16 . On the upper electrode 18, a plurality of through holes or gas discharge ports I8a for forming a shower head are formed. A gas supply pipe 24 from the processing gas supply source 22 is connected to the gas inlet port 20 provided on the back surface of the upper electrode 18. A flow rate adjuster (MFC) 26 and an on-off valve 28 are provided in the middle of the gas supply pipe 24. An exhaust port 30 is provided at the bottom of the vacuum chamber 10, and an exhaust device 34 is connected to the exhaust port 30 via an exhaust pipe 32. The exhaust unit 34 has a vacuum pump such as a turbo molecular pump to decompress the plasma space in the vacuum chamber 10 to a desired degree of vacuum. A substrate loading/unloading port (not shown) is provided on a side wall of the vacuum chamber 10, and a load-lock chamber of the adjacent chamber is connected to the substrate carrying port via a gate valve ( Not shown). In the plasma etching apparatus, the lower electrode 16 is formed in an electrical cathode coupling configuration. The upper electrode 18 is connected to the ground potential via the vacuum chamber 10 (ground). On the other hand, the first and second high-frequency power sources 40 and 42 are electrically connected to the lower electrode 16 via the first and second integrators 36 and 38, respectively. The first high-frequency power source 40 mainly contributes to the generation of plasma. Therefore, the ideal state is to use the first high frequency (hereinafter referred to as "power source" having a frequency of 10 MHz to 30 MHz (for example, 13.56 MHz or 27.12 MHz). High frequency.) RFS, output at the desired power (P〇wer). The first integrator 36 is for integrating the impedance of the high frequency power supply 40 side and the load impedance of the lower electrode 6 side, and has an integrated circuit for matching -11 - 1311782 (9) (matching) adjustment. 44' and a band-pass filter 46 for protecting the high frequency power supply 40. The integrating circuit 44 is an L-type circuit composed of two variable capacitors 48' 50 and one coil 52. More specifically, a capacitor 48 is connected between the input terminal (node Na) and the ground potential, and the coil 52 and the capacitor 50 are connected in series between the input terminal (node Na) and the output terminal (node Ne). By variably adjusting the capacitances of the two variable capacitors 48' 50, the load impedance on the side of the electrode 16 including the lower portion of the integrated circuit 44 and the impedance on the side of the first high frequency power source 40 including the band pass filter 46 can be made. In appearance, the result is. The band pass filter 46 is a series resonance circuit in which the coil 54 and the capacitor 56 are connected in series. It is selectively connected only to the high frequency band near the high frequency RFS for power supply. Even if the high frequency RFb from the second high frequency power source 42 passes through the integrating circuit 44', it is blocked by the band pass filter 46 and is not transmitted to the first high frequency power supply 40. The second high-frequency power source 42 mainly assists in the adjustment of the self-bias voltage Vde. Therefore, the second high-frequency (hereinafter referred to as "high-frequency for power supply" having a frequency of 2 MHz to 6 MHz (for example, 3·2 ΜΗζ) is preferable. .) RFb' is output at the desired power. The second integrator 38 is a T-type circuit composed of two variable capacitors 58, 60 and one coil 62 for integrating the impedance on the high frequency power source 42 side and the load impedance on the lower electrode side 6 side, and The integrated circuit for matching adjustment and the filter circuit for protecting the high frequency power source 42. More specifically, there is a capacitor 58 and a coil 62 connected in series between the integrator input terminal on the high frequency power source 42 side and the integrator output terminal (node N.) on the lower 12-1311782 (10) portion electrode 16 side. A capacitor 60 is connected 'connected between the junction point (node Nb) of the capacitor 58 and the coil 62 and the ground potential. In the τ-type circuit, the 'coil 62' of the last output stage is formed by a combination of a capacitor 60 which is connected to the terminal or the capacitor 60, which constitutes a high-cut filter, and has an occlusion. The power supply from the first high-frequency power source 40 functions as a high-frequency RFS. In order to secure the high-frequency blocking function ', it is preferable to form the impedance of the coil 62 to be 1 ohm or more. On the other hand, by variably adjusting the capacitances of the two variable capacitors 58, 60, the load impedance including the side of the electrode 16 on the lower side of the integrated circuit (58, 60, 62) and the second high frequency are obtained. The impedance on the side of the power source 42 is identical in appearance. Further, the supply line 64 between the integrator output terminal (node N e ) and the lower electrode 16 may also be constituted by a feed bar. As described above, in the plasma etching apparatus of the present embodiment, the power supply high-frequency RFS and the bias high-frequency RFb are superimposedly applied to the double-frequency overlapping application mode of the lower electrode 16, and the coil 62 is provided by the last output section. The T-type circuit of the three elements (58, 60, 62) constitutes the integrator 38 on the low frequency side, and the coil 62 has the high frequency power supply 42 for protecting the low frequency side (i.e., the bias high frequency RFb side). High frequency cutoff filter. With this configuration, the size and cost of the integrator 38 can be greatly reduced. In the plasma etching apparatus, when the etching is performed, the gate valve is first opened, and the substrate G to be processed is carried into the vacuum chamber 10 and placed on the lower electrode 16. Then, a predetermined etching gas is introduced into the vacuum chamber 1' from the processing gas supply source 22' at a predetermined flow rate and flow rate ratio. -13- (11) 1311782 The pressure in the vacuum chamber 10 is set by the exhaust device 34. . Further, from the first high-frequency power source 40, a high-frequency RFS for power supply is applied to the lower electrode 16 at a predetermined power, and at the same time, a bias voltage is applied from the second high-frequency power source 42 at a predetermined power. Frequency RFS. The etching gas ejected from the shower head (upper electrode) 18 is plasma-formed between the electrodes 16 and 18 by high-frequency discharge, and the radical of the substrate G is etched by radicals or ions generated by the plasma. surface. Here, the high-frequency RFS for power supply applied to the lower electrode 16 by the first high-frequency power source 40 mainly acts on the high-frequency discharge between the lower electrode 16 and the upper electrode 18, thereby enhancing the action on the plasma. generate. In general, in the parallel plate type, the higher the frequency of the high frequency applied between the electrodes, the higher the plasma density can be, but the electrode center portion side is more likely to become higher than the electrode edge portion side. Further, the higher the power of the high-frequency RFs for the power supply, the higher the energy to be supplied to the plasma, and the higher the plasma density. However, the plasma tends to concentrate on the center of the electrode, resulting in a decrease in the uniformity of the plasma density distribution. In the present embodiment, as described above, this problem can be solved by the dual-frequency overlapping application method of the high-frequency RF s for power supply and the high-frequency RFb for bias. The bias high frequency RFb' applied to the lower voltage 16 by the second high frequency power source 42 first acts on the magnitude (absolute 値) of the negative self-bias voltage Vde generated in the lower electrode 16 or the substrate G, thereby functioning The electric field intensity of the ions in the plasma is introduced into the substrate G. In general, the self-bias voltage Vd. When there is a maximum point on the frequency axis, when the frequency of the bias high frequency RFb is too high (6 MHz or more), Vde will become smaller, and when the frequency of the bias high frequency RFb becomes too low, 'Vde also It will become smaller. From this point of view, -14 - 1311782 (12) In the present embodiment, the bias high frequency RFb is set in the range of 2 MHz to 6 MHz. The inventor of the present invention repeated the experiment several times in the parallel plate type RIE plasma etching apparatus of the dual-frequency overlapping application mode of the present embodiment, and found that the high frequency RFS and the bias voltage were appropriately selected by the power source. Other etching conditions such as frequency, power, pressure or etching gas of high-frequency RFb can be used to control not only the chemical etching of the radical base but also the physical etching of the ion base. Control, and regarding the specific material to be etched, it is also possible to improve the uniformity of the plasma density distribution or to obtain an etching ability comparable to that of an ICP (Inductively Coupled Plasma Etching Apparatus). Next, a specific embodiment of the plasma etching method of the present invention will be described. [Example 1] Using the plasma etching apparatus of Fig. 1, in the etching of aluminum (A1), the power Ps of the high-frequency RFS (13·56 ΜΗζ) for the power supply and the high-frequency RFb (3.2 MHz) for the bias voltage were used. The power Pb was used as a parameter to evaluate the uniformity of the plasma density distribution. In the multilayer wiring structure in which the wiring of aluminum is provided, in order to facilitate the embedding of the insulating film, it is desirable to perform taper etching on the lower layer side, in particular, the lowermost aluminum wiring. Therefore, in the inflection of the FPD, the anisotropic etching is performed, so that it is preferable to lower the pressure to increase the power Ps of the high-frequency RFS for power supply. However, as shown in Comparative Examples 1'2 and 3 of Figs. 4 to 6, 'the single frequency application method using only the high frequency RFB for power supply without applying the high frequency RFb for biasing at -15-(13) 1311782 In the case where the power ps of the RFS is higher, the plasma density becomes higher at each position as the pressure in the vacuum chamber is lower. However, there is a problem that the vicinity of the electrode center portion is abnormally protruded and becomes high. Further, as shown in Fig. 4, even if the electrode gap (GAP) becomes large, the uniformity of the plasma density is lowered. More specifically, in the electrode gap (GAP) of 21 Omm, the pressure is set to SmTorr or less, and the power Ps of the power supply high-frequency RFS is set to a condition of 1000 W or more, and the uniformity is good. The plasma density distribution is very unlikely. In the first embodiment of the 'dual-frequency overlapping application method, as shown in the second and third figures, the 'ideal state' is proportional to the power Ps of the power supply high-frequency RFS by 1 / 1 〇 The above ratio, the power P b ' of the bias high frequency RFb is selected to achieve a substantially average plasma density distribution in the above-described conditions. In this way, it was confirmed that the desired etching process with excellent etching uniformity was performed on the aluminum film on the substrate G using the plasma etching apparatus of Fig. 1 . Further, both titanium and titanium-containing metals belong to the same type of material to be etched as aluminum. These metals can also be subjected to a desired etching process having excellent etching uniformity. In addition, in the data of the second and fourth figures, the plasma light inside the vacuum chamber (especially between the two electrodes) was evaluated by visual observation through a screen (not shown) provided on the side wall of the vacuum chamber 10. In the state, when the phenomenon that the plasma light-emitting region is concentrated in one place (usually the center portion), the mark of the uniformity (X) is marked as 'the phenomenon that the plasma light-emitting region is approximately the same.' Good (0) mark. On the other hand, the data of the 3rd - 16th (14) 1311782, 5th, and 6th are measured by the plasma absorption probe (PAP) method of the network analyzer to measure the plasma density distribution. As an electron density distribution. Further, in the above-described Example 1 and Comparative Examples 1 and 2, chlorine gas C12 (flow rate 300 or 2000 sccm) was used as the etching gas. However, as shown in the reference example of Fig. 6, it was found that chlorine gas was present. The uniformity of the plasma density distribution is improved by mixing argon (Ar) at an appropriate flow ratio (ideal state of Cl2/Ar = 125/75 to 100/100). [Example 2] Using the plasma etching apparatus of Fig. 1, in the etching of aluminum alloy (AINd) of an aluminum alloy, the etching speed was evaluated using the power Pb of the bias high frequency RFb (3.2 MHz) as a parameter. the size of. For other major etching conditions, the electrode gap (GAP) is set to 140 mm, the etching gas is set to Cl2 (flow rate 300 sccm), the vacuum chamber pressure is set to 5 mTorr, and the temperature (upper electrode (T) / lower electrode (B) / Vacuum chamber side wall (W)) = 60/20/60 °C, power supply high frequency RFS (13.56MHz) power Pb is set to 2000W. As the etching gas, a chlorine-based gas such as BC13 can also be used. Further, the substrate to be processed G is a detached substrate for LCD of 550 x 650 size, and as shown in Fig. 8, the etching rate is tested at a plurality of measurement points (1 to 14) on the substrate, at the center portion (7, 8) and In the middle part (4, 5, 10, 1 1 ), the average 値 is obtained, and at the edge (1, 2, 3, 6, 9, 1 2, 1 3, 1 4 ), the maximum 値 and minimum 求 are obtained. . -17- 1311782 (15) As shown in the graph of Fig. 8, the higher the power Pb of the bias high frequency RFb (3 · 2 ΜΗζ ), the higher the etching rate of aluminum and ammonium, Pb = 1000 W As described above, an etching rate of about 2000 A/min or more can be obtained. Therefore, it has been confirmed that sufficient etching ability comparable to that of ICP (Inductively Coupled Plasma Etching Apparatus) can be obtained by etching processing of an aluminum alloy using the plasma etching apparatus of Fig. 1 . Further, since the uniformity of the plasma density can be achieved by the double-frequency overlapping application method of the present invention, the improvement of the etching uniformity can be achieved. In addition, IT◦ is also an etched material of the same kind as aluminum alloy, and the alloy can also obtain the same etching ability as those for aluminum alloy. In the etching of the tantalum oxide film (Si〇2) using the tantalum substrate or the tantalum layer (Si) as the underlayer by the plasma etching apparatus of Fig. 1, the power Pb of the bias high frequency RFb (3.2 MHz) is used as the bias voltage. Parameters, test each etching speed and selection ratio. For other major etching conditions, the electrode gap (GAP) is set to 140 mm, the f insect gas is set to CHF3 (flow rate: 200 sccm), the vacuum chamber pressure is set to 5 mT 〇rr, and the temperature (upper electrode (T) / lower electrode (B) / vacuum chamber side wall (W)) = 60 / 20 / 60 °C, power Pb for power supply high frequency RFs (27.12MHz) is set to 2500W. Here, the frequency of the high-frequency RFS for power supply is set to 27.12 MHz in order to obtain a plasma having a higher density than 13.56 。. The etching gas is not limited to CHF3, and any one of CF4, CH2F2, and C4Fs or a mixture of two gases and H2 and Ar may be used. Further, a mixed gas of SF6, 02, and a gas can also be used. As shown in the graph of Fig. 9, the higher the power Pb of the bias high frequency RFb-18-(16) 1311782 (3·2ΜΗζ) is, the larger the etching speed of SiCh is, the larger the etching rate of SiCh is, P b = 1 〇〇 Above 0 W, an etching rate of about 1000 A / m in or more can be obtained, and a selection ratio of about 10 or more can be obtained. As described above, it was confirmed that the plasma etching apparatus of Fig. 1 was used by the etching process of the Si〇2 film, and the sufficient etching ability comparable to that of the icp (inductively coupled plasma etching apparatus) was obtained. Further, since the uniformity of the plasma density can be achieved by the double-frequency overlapping application method of the present invention, the etching uniformity can be improved. The basic form of the plasma etching apparatus (Fig. 1) of the above embodiment can also be applied to other plasma processing apparatuses, for example, plasma CVD, plasma oxidation, plasma nitridation, sputtering, etc. Deformed in various plasma processing devices. Further, the substrate to be processed of the present invention is not limited to the FPD substrate, and may be a semiconductor wafer, a light mask, a CD substrate, a printed substrate or the like. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a view showing the configuration of essential parts of a plasma etching apparatus according to an embodiment of the present invention. Fig. 2 is a graph showing the results of evaluation of the plasma density distribution characteristics by visual observation in the first embodiment. Fig. 3 is a graph showing the electron density distribution characteristics of the first embodiment. Fig. 4 is a graph showing the results of evaluation of the plasma density distribution characteristics by visual observation in a comparative example. Fig. 5 is a graph showing electron density distribution characteristics of a comparative example. -19- (17) 1311782 Fig. 6 is a graph showing the electron density distribution characteristics of a comparative example. Fig. 7 is a graph showing electron density distribution characteristics of a reference example. Fig. 8 is a graph showing the bias power dependence of the etching rate in the second embodiment. Fig. 9 is a graph showing the bias power dependence of the etching rate in the third embodiment. ❿ Description of main components and symbols] 10 vacuum chamber (processing container) 1 6 lower electrode 1 8 upper electrode 22 processing gas supply source 3 exhaust device 36 first (power supply) integrator 38 second (biasing) integrator 40 first (for power supply) high-frequency power supply 4 2 second (for bias) high-frequency power supply 58 variable capacitor 60 variable capacitor 6 2 coil