200540988 (1) 九、發明說明 【發明所屬之技術領域】 本發明係有關於電漿處理裝置，例如蝕刻裝置、氮化 • 裝置或氧化裝置，例如應用在例如半導體基體或液晶基體 ， 的半導體製程中者。更詳細地說，本發明係有關於一種電 漿處理裝置，藉由之可以使基體（欲處理物體）旁邊的電 漿活性物種或活性分子的量成爲所需的密度（或濃度）及 Φ 分佈情形。 【先前技術】 爲改善在半導體基體上所製成之晶片的產出率，在電 漿處理裝置內，半導體基體整個表面上的處理均勻度是相 當重要的。爲能在半導體基體表面上得到處理均勻度，在 電漿處理裝置上曾有許多種的嚐試。多孔質板的使用即爲 其一例。 舉例來說，日本早期公開專利申請案公開第2000-5 8294號中即顯示一種CVD (化學蒸汽沉積）裝置，其中 爲確保薄膜能以均勻的厚度沉積在半導體基體上，必須要 變化多孔質板的厚度，以控制供應至半導體基體表面上各 個點的反應氣體的量。此習用技藝例子之裝置是一種CVD 裝置，其中半導體基體是在相當高壓力下加以處理的，而 其結構則是設置成能夠在黏滯流動壓力區域內進行空氣流 的控制。爲能在多孔質板頂面與底面間形成大壓力差，且 使流通過孔洞的氣體流率均勻，在多孔質板上設有大量極 -4- 200540988 (2) 小直徑Φ = 0· 1至1公釐的孔洞。此多孔質板的厚度分佈情 形是在參照實驗結果下，根據黏滯流動關係式來加以決定 的’其中穿過孔洞的氣體流率是正比於深度的平方。雖然 此習用技藝例子適合應用在要在半導體基體上均勻沉積出 薄膜的情形中，但是其並不適合於要以較低壓力來處理半 導體的情形中，例如蝕刻。這是因爲在其一種需求中，由 於蝕刻製程是在較低壓力的分子流壓力區域內進行的，所 Φ 以厚度差要加大，以供依據多孔質板之厚度分佈情形來進 行氣體流率的控制，而在另一種需求中，多孔質板必須要 _ 儘可能的薄，以有效地利用離子，而此二種需求之間是爲 互相矛盾。 曰本早期公開專利申請案公告第1 1 -3 5 0 1 43號中顯示 一種多孔質板，可應用在蝕刻裝置上。在此例中，在與半 導體基體相對的一表面上設有微波傳送窗口，而電漿即可 由該微波所生成。此微波傳輸窗口包含有三個窗口。最上 # 方的窗口是用來將大氣與真空互相隔離開。中間及底部的 窗口設有傳導用的小孔，反應用氣體係均勻地供應至半導 體基體表面上。此種具有三窗口並可做爲多孔質板的微波 傳輸窗口，係設置成可使窗口內的壓力變高，而其間的空 間變小，以防止在三窗口結構之窗口內產生放電。此習用 技藝例子所根據的槪念是，該微波傳輸窗口（多孔質板） 可以使供應至半導體基體表面上各點的反應氣體的量變成 均勻，而能在微波傳輸窗口（多孔質板）的底部形成均勻 的微波，藉由之供應至半導體基體表面上各點的電漿離子 -5- 200540988 (3) 的量會變得均勻。此外，其設有一具有孔洞的槽孔天線， 以在微波傳輸窗口的底部形成均勻的電漿，因此可以使微 波傳輸分佈大致上成爲均勻。 但是，如果槽孔天線是設計用來提供大致上均勻的微 波傳輸分佈的話，雖然這可在特別限制之條件下，在微波 傳輸窗口的底部形成均勻的微波電漿，但在其他的條件 下，其將不易在該處形成均勻的微波電漿。推測上這是因 φ 爲微波模式會隨著電漿密度而變，故無法穩定地激發電 漿。 另一個例子是揭露於日本早期公開專利申請案公告第 5-3 45 9 82號內，其中微波表面干涉波是形成於槽縫之間， 而能在不造成模式跳躍（Μ 〇 d e J u m p )的情形下，穩定地 激發微波電漿。在此習用技藝例子中，由於是在分子流壓 力區域內應用擴散作用來在半導體基體旁邊造成均勻的電 漿分佈，因此會有使電漿處理腔室及電漿處理裝置尺寸變 • 大的趨勢。因此，曾有人嚐試要使用多孔質板來使基體旁 邊的電漿分佈均勻化而同時使電漿處理裝置的尺寸縮小。 但是，雖然在使用具有例如不規則分佈而直徑爲數公釐之 小孔洞的多孔質板時，其可以使基體四周之電漿分佈成爲 均勻，但是電漿與多孔質板間的接觸面積卻會加大，且電 漿密度會顯著地降低。這將造成基體處理時間的加長。另 一方面，雖然可以使用較大的孔洞來減少與電漿間的接觸 面積，以抑制電漿的降低，但是每一孔洞的影響會變大， 故需浪費大量的時間及精力來使用試誤法。因此這是不實 -6 - 200540988 (4) 用的。 【發明內容】 因此，本發明的目的在於提供一種電漿處理裝置’藉 由之位在欲處理物體旁邊電漿活性物種可調整成所需的密 度（濃度）及分佈。 本發明的另一目的在於提供一種電漿處理裝置’其具 鲁 有一多孔質板設置於其內，可以有效地使欲處理物體旁邊 的電漿分佈成爲均勻，而同時可以非常輕易而無須仰賴試 誤法即能抑制電漿密度的降低。 根據本發明的一項觀點，爲達成上述目的之至少一 者，其提供一種電漿處理裝置，包含有：一電漿生成部； 以及一多孔質板，設置在該電漿生成部與一欲處理物體之 間，其中該多孔質板具有多個孔洞，其等就形狀、尺寸及 分佈等因素中之至少一者而言，係製做成不均勻的。 Φ 根據本發明的另一觀點，其提供一種電漿處理裝置， 包含有：一電漿生成部；以及一多孔質板，設置在該電漿 生成部與一欲處理物體之間，其中該多孔質板具有多個孔 洞，其等的形狀及分佈係根據該電漿生成部之活性物種的 分佈情形及擴散之計算結果而決定的，因此在欲處5里物體 旁邊的電漿活性物種會具有所需的濃度及分佈情形° 根據本發明的再另一觀點，其提供一種用來設計具有 電漿生成部及位在該電漿生成部與一欲處理物體之間之多 孔質板的電漿處理裝置的方法，包含有下列步驟：根據電 200540988 (5) 漿生成部內之活性物種的分佈及擴散的計算結果而決定該 多孔質板內之孔洞的形狀及分佈，因此而使得欲處理物體 旁邊的電漿活性物種具有所需的濃度及分佈情形。 簡言之，根據本發明，其係使用一種多孔質板，其上 的孔洞就形狀、尺寸及分佈情形而言是不均勻的，藉由之 可以提供各種不同密度及分佈情形的電漿活性物種。詳細 地說，這些孔洞的形狀、尺寸及分佈情形是根據活性物種 φ 在電漿生成部內的分佈及擴散計算結果而決定的。這可有 效地避免試誤法所需的大量時間及精力，且可輕易而便利 地得到一種能確保所需之電漿活性物種密度及分佈情形的 多孔質板。 本發明的這些及其他目的、特點及優點，將可自下面 本發明較佳實施例的說明，並配合所附圖式，而更淸楚得 知。 # 【實施方式】 根據本發明之較佳型式的電漿處理裝置包含有一電漿 處理部，以及一多孔質板，設置在該電漿處理部與欲處理 之基體之間，其中該多孔質板上的孔洞的形狀及分佈是根 據活性物種在電漿生成部內的密度分佈與擴散之計算結果 而決定的，以確保該基體旁邊的電漿活性物種會有均勻的 分佈情形。根據此實施例，該多孔質板是根據活性物種在 電漿生成部內的密度分佈與擴散之計算結果來加以設計 的。因此可以無須依賴試誤作業來設計大直徑的孔洞，故 200540988 (6) 能得到一種電漿處理裝置，其可以在基體旁邊提供具有良 好均勻性的電漿活性物種分佈情形，而同時可以抑制電漿 的降低。 在此，活性物種在電漿生成部內的密度分佈可以利用 例如電子探針來加以偵測。此外，擴散計算結果可以利用 下列稱爲雙載子擴散方程式的方程式（1 )爲之。其已知 藉由擴散而到達一壁的電漿會因在該壁上的復合淬滅 (Recombination Quenching)作用而消滅，其量可由下列 的方程式（2 )來加以表示。計算這些方程式所需的擴散 系數及類似者可根據利用電子探針所進行之實驗來加以決 定。 Q = DxAN/LxS ... ( 1 ) 在方程式（1)中，Q是擴散量，D是擴散系數，AN 是密度差，L是長度，而S是面積。 Q，=NxCxS ... ( 2 ) 在方程式（2)中，Q’是復合淬滅的量，N是電漿密 度，C是系數，而S是面積。 根據這些計算公式及電漿生成部內的密度分佈’其可 以決定面積及孔洞的分佈，以使基體旁邊的電漿密度成爲 均勻分佈。 依據如此設計的結果，位在或靠近於具有較高電漿生 成密度之區域內的孔洞會具有較小的直徑，而位在或靠近 於具有較低電漿生成密度之區域內的孔洞會具有較大的直 徑。 -9- 200540988 (7) 多孔質板的厚度在圍繞著具有較大截面積之孔洞的部 位係製做成較薄，以供進一步減低電漿在孔洞壁上的復合 淬滅情形，而具有較小截面積之孔洞則須增加，以保持整 體的平衡。這可提供一種電漿處理裝置，其中可加大電漿 通過率，但能維持基體旁邊的電漿分佈的均勻性。 多孔質板可以是由一種熱膨脹系數約略小於ΐχΐ(Γ5/ °c的材料製成，且在此情形下，可以抑制多孔質板在電漿 φ 處理過程中因溫度升高至5 00 °C時所造成的形狀變化。因 此，這可提供一種電漿處理裝置，其中電漿活性物種在基 體旁邊的分佈是穩定而均勻的。此多孔質板上的孔洞直徑 大致上是在1公釐至5 0公釐的範圍內，但必須有約〇. 1 公釐的加工精度。此多孔質板是使用在約低於5 00 °C的條 件下。因此，透過簡單的計算，其熱膨脹系數最好是小於 約Ixl0_5/°C。更好的是，其係由熱膨脹系數小於ΐχΐ〇_6/ °C的材料所製成的，例如石英，其係含矽的陶瓷材料。 φ 多孔質板上所有孔洞的截面積可以約略相同的比例來 加以放大或縮小。這可提供一種電漿處理裝置，藉由之可 以輕易而便利地改變欲處理之基體旁邊的電漿活性物種密 度，而不用改變該基體旁邊的電漿活性物種分佈情形。這 之所以可以達成是因爲藉由擴散而通過多孔質板內之孔洞 的電漿的量是約略正比於多孔質板之所有孔洞的總截面積 之故。 該多孔質板可以製做成使其上之孔洞的中心是大約沿 著同軸且同心之圓圈設置的，而沿著同一圈圓圈設置的孔 -10- 200540988 (8) 洞則是約略具有相同的截面積。這可提供一種電漿處理裝 置，藉由之可以對具有相似之中央對稱性的圓形基體，例 如半導體基體，做精密而均勻的電漿處理。 此多孔質板可以製做成設有中心大約爲等距離設置的 孔洞。這可以提供一種電漿處理裝置，藉由之基體的整體 表面可以做均勻的電漿處理。 此多孔質板的孔洞截面積可以稍微加大些，以確保基 φ 體旁邊的活性物種會包含有離子。這可提供一種電漿處理 裝置，其中離子會是主要的反應因子，如同蝕刻程序或氮 化程序一樣。 此多孔質板的孔洞截面積可以稍微減小些，以確保基 體旁邊的活性物種會包含有中性自由基。這可提供一種電 漿處理裝置，其可進行不會造成半導體性能大幅度劣化的 電漿處理製程，如同使用氧自由基做爲主要成份的氧化程 序。 φ 此電漿處理裝置可以包含有一電漿處理腔室，設有用 來傳遞微波的電介質構件、用來將微波導入該電漿處理腔 室內的微波導入裝置、一基體、及一設置在該基體與該電 介質構件之間的多孔質板，此裝置係配置成可因微波而激 發表面波電漿。這可提供一種電漿處理裝置，藉由之該電 漿生成部可以局部形成在電介質構件旁邊’而多孔質板可 以精確而簡易地設計。在此種微波電漿處理裝置中’微波 會被由該微波所生成之電漿加以限制在電介質構件的旁 邊。因此，其所具有的一項特點在於電漿僅會產生在電介 -11 - 200540988 (9) 質構件的旁邊，並藉由擴散而朝向基體2傳送。因此，根 據電漿生成部的分佈及擴散，其將可以良好的精度來設計 多孔質板的孔洞及其等的分佈。 微波之導入至電漿處理腔室可以利用設有槽縫的無端 式圓形波導來爲之。這可提供一種電漿處理裝置，藉由之 電漿生成部的密度分佈比較不會受到電漿處理條件的影 響，例如氣體壓力及所用之氣體的型式等，且藉由之其將 φ 可在多種不同的電漿處理條件下使用單一種多孔質板。 在本發明中，在多孔質板上並不一定需要設置沿著同 軸且同心之圓圏分佈的孔洞。他們可以任何所需的方式來 設置。此外，孔洞的形狀也不限於圓形。任何形狀均可使 用，例如矩形、三角形或星形（五芒星形）。本發明的多 孔質板可以應用在任何型式的電漿處理裝置上，只要是電 漿生成部僅存在於局部區域內即可。例如說，其可以是微 波電漿，或是感應耦合式電漿（ICP)。 Φ 下面將配合所附圖式來說明本發明的較佳實施例。 〔實施例一〕 本發明的第一實施例將參閱圖式中之第1圖所示的微 波電漿處理裝置的範例來加以詳細說明。在第1圖中，以 參考編號1標示的是圓柱狀的電漿處理腔室’而以參考編 號2標示的則是欲處理的基體。以參考編號3加以標示的 是基體承載台，用以承載基體2於其上。以參考編號4加 以標示的是多孔質板，而以參考編號5標示的則是處理用 -12- 200540988 (10) 氣體導入裝置。以參考編號6加以標示的是排氣口，而以 參考編號8標示的則是設有槽縫的無端式圓形波導，用以 將微波導入至電漿處理腔室1內。以參考編號1 1加以標 示的是槽縫，其等係設置該圓形波導8上，而具有對應於 該管內之微波的一半或四分之一波長的節距。以參考編號 7加以標示的是電介質材料窗口，用以將微波導入至電漿 處理裝置內，而以參考編號1 〇標示的則是設置在波導8 φ 內的冷卻水通路。電漿處理腔室1及電介質材料窗口 7的 內壁是由石英製成，不會對基體2造成金屬污染。半導體 承載台3是由以氮化銘爲主要成份的陶瓷材料製成的。 多孔質板4是由熱膨脹系數爲5xl(T7/°C (幾乎不會 因熱而膨脹）的石英材料製成的，不會造成金屬污染。每 一孔洞的截面積及其分佈是根據生成於電介質材料窗口 7 旁邊的電漿生成部的密度分佈，以及擴散結果，而設計 的。就多孔質板上的孔洞而言，要將波導8及圓柱狀電漿 φ 處理腔室1的中心對稱性列入考慮，如第2圖中所示，故 這些孔洞係製做成圓柱狀，且他們是設置在中心及沿著一 些同心圓圈以大約是等距離的方式分佈的。此外，在同樣 考量到中心對稱性之下，這些沿著某一或某些圓圏設置的 孔洞要具有大約相同的截面積。相鄰孔洞間的距離是大約 等於20公釐。孔洞的直徑大約是在1 〇至20公釐的範圍 內。所有孔洞之總截面積與電漿處理腔室1的截面積的比 値（下文中稱爲“開口率”）大約是等於0.2。 現在將說明利用此實施例之電漿處理裝置在基體2上 -13- 200540988 (11) 實施氮化處理的例子。首先利用輸送裝置（未顯示）將表 面上形成有2nm厚氧化物膜的矽質基體輸送至基體承載台 3上，並將其置放至該台上。接著利用排氣系統（未顯 示）將電漿處理腔室1加以排氣至不大於〇. 1 Pa的程度。 接著將500 seem的氮氣經由處理用氣體導入裝置5加以 注入至電漿處理腔室1內。其後調整設置在排氣系統內的 導通閥（Conductance Valve )，以將處理腔室1維持在 Φ 130Pa。接下來啓動微波電壓源，以經由無端式圓形波導8 及電介質材料窗口 7將1.5kW的微波供應至電漿處理腔室 1內，進而在電漿處理腔室1內生成電漿。當由微波所激 發的電漿密度變成大於約lxl 〇]1cm3時，微波即無法再進 入電漿內，因此之故電漿僅會生成在電介質材料窗口 7的 極表面（Polar Surface)上。電漿內的氮離子會在擴散 時，向前進而到達多孔質板上。他們有一部份會因在多孔 質板表面上復合淬滅而消失，但他們另有一部份會通過多 # 孔質板4上的孔洞，並由之加以調整而在基體2的表面上 形成均勻的氮離子分佈，而這些離子即會如此而到達至基 體2的表面上。移動靠近至基體2的氮離子會因形成在欲 加以處理之基體2的表面上離子鞘層的作用而加速，因此 他們會入射至基體2上而造成氧化矽膜的氮化。在開始供 應微波經過三分鐘後，將微波電壓源加以停止，並中斷氮 氣的供應。在將電漿處理腔室1抽空至不大於0. 1 Pa的程 度後，將基體2自電漿處理腔室1內取出。 在完成氮化處理後，再使用橢圓偏光計（KLA_Tenc〇r -14 - 200540988 (12) 公司）來測量基體2之表面上由氧化矽膜轉化而 矽氮化膜的厚度增量。其結果爲2.1 nm±2%。這 多孔質板所能達成者約高六倍的均勻度，如第3 看到的。 如前所述，根據此實施例的電漿處理裝置， 用較大直徑孔洞的多孔質板，亦可在基體表面上 的均勻度。此外，藉由依據電漿生成部的密度分 φ 計算結果來設計該多孔質板，其將可以避免使用 需消耗的大量時間及精力。因此可以輕易而便利 孔質板。 〔實施例二〕 在此實施例中，第一實施例中的微波電漿處理 多孔質板4係由開口率約爲0.1的多孔質板加以取 氮化處理則是以和第一實施例相同的方式施用在 φ 上。此第二實施例中所用之多孔質板4上每一孔洞 積均是第一實施例中所用之多孔質板中的孔洞的一 此孔洞的直徑是1 /万（2的平方根）’其大約是在 公釐的範圍內。此多孔質板4上孔洞的分佈情形是 第一實施例。 在完成氮化處理後，再使用橢圓偏光計（KLA· 公司）來測量基體2之表面上由氧化矽膜轉化而成 矽氮化膜的厚度增量。其結果爲I n m + 2 %。將依據 施例加以進行氮化處理過的基體2上的薄膜厚度分 的氧化 不使用 中所可 使是使 到處理 及擴散 誤法所 提供多 裝置的 代，而 基體2 的截面 半。因 7至1 5 類似於 Tencor 的氧化 第二實 佈與第 -15- 200540988 (13) 一實施例中所得到者相比較’如第4圖中所示’可以看到 分佈的形狀是相似的’但在第二實施例中’薄膜的厚度大 約只有一半。 如前所述，可以看到’多孔質板上所有孔洞的截面積 可以大約相同的比例來加以加大或縮小’而如此進行後’ 其將可以得到一種電漿處理裝置’其可以很便利地將氮化 膜的厚度增加或減小’而同時保有氮化處理結果的均勻 〔實施例三〕 在此實施例中，其係以第5圖中所示之多孔質板4來 取代第一實施例之微波電漿處理裝置的多孔質板4，但仍 以和第一實施例相同的方式在基體2上施行氮化處理。就 此第三實施例所用之多孔質板4上的孔洞而言，在第一實 施例中所用的多孔質板上位在自中心算起之第一圈同心圓 • 上的孔洞係被去除掉，而另一方面，中心孔洞的尺寸則加 大。此外，開口率是大約等於0.22。由於自中心算起之第 一圏同心圓上的孔洞已被去掉，因此即使將開口率擴大至 約0.22，其仍可以確保相鄰孔洞間具有足夠的間距。因此 多孔質板可以具有足夠的機械強度。 在完成氮化處理後，再使用橢圓偏光計（KLA-Tencor 公司）來測量基體2之表面上由氧化矽膜轉化而成的氧化 矽氮化膜的厚度增量。其結果爲2.2nm土2%。與第一實施 例相比較下，薄膜厚度增加約1 〇%。 -16- 200540988 (14) 如前所述，多孔質板上相鄰之同軸且同心圓圈間的間 距可以適度地加以改變’這可提供一種電漿處理裝置’其 可藉由在孔洞間保留足夠的間距而在能加大開口率的同 時，仍能保持多孔質板的強度，且藉由之處理速度可以提 闻。 〔實施例四〕 φ 在此實施例中，第一實施例之微波電漿處理裝置中的 槽縫被變更成弧形，如第6圖中所示，而且多孔質板4也 被開口率約爲0.3者加以取代，此係對應於要由該等槽縫 所生成的電漿生成部的密度分佈。氮化處理是以和第一實 施例相同的方式來加以進行。根據此第四實施例中所用的 多孔質板4，在和第一實施例相比較下，其開口率可以加 大約5 0 %。這是因爲：在根據第一實施例的槽縫分佈中’ 因爲電漿生成部密度分佈具有環狀的形狀，因此開口率要 φ 設定成不會在多孔質板之中心孔洞與相鄰之孔洞間產生干 涉；但是根據此第四實施例，由於電漿生成部密度分佈是 均勻地擴張至電介質材料窗口 7的整個表面上，因此孔洞 的直徑會較均勻，而相鄰孔洞間幾乎不會產生干涉。因此 可以將開口率加大。 在完成氮化處理後，再使用橢圓偏光計（KLA-Tencor 公司）來測量基體2之表面上由氧化砂膜轉化而成的氧化 矽氮化膜的厚度增量。其結果是，在和第一實施例相比較 下，薄膜厚度增加約50%。 -17- 200540988 (15) 如前所述，其可以使用能夠造成較均勻之電漿生成部 密度分佈的槽縫分佈，這可提供一種電漿處理裝置，藉由 之開口率可以加大，且處理速度可以提高。 〔第五實施例〕 在此實施例中，第一實施例之微波電漿處理裝置中的 多孔質板4是由開口率約爲0.2 1者加以取代，而氮化處 φ 理則以和第一實施例相同的方式施行在基體2上。在此第 五實施例中，多孔質板上圍繞著較大直徑孔洞的區域是製 做成較薄，如第7圖中所示。因此之故，可以減低孔洞壁 上的電漿復合淬滅情形。由於要將較小直徑之孔洞的直徑 加大，以維持整體的平衡，因此多孔質板4的開口率會加 大。 在完成氮化處理後，再使用橢圓偏光計（KLA-Tencor 公司）來測量基體2之表面上由氧化矽膜轉化而成的氧化 • 矽氮化膜的厚度增量。其結果爲2.2nm±2%。與第一實施 例相比較下，薄膜的厚度增加約1 0%。 如前所述，圍繞著多孔質板上較大直徑孔洞周圍的區 域之厚度係製成較薄的，這可提供一種電漿處理裝置，藉 由之較小直徑之孔洞在直徑上可以加大，且藉由之處理速 度可以提高。 根據前面所述的本發明實施例，其係使用具有較大孔 洞直徑的多孔質板來減少電漿與孔洞壁部間的接觸，並抑 制電漿復合淬滅。因此可以縮短基體的處理時間，且同時 -18- 200540988 (16) 可以確保基體表面上的處理均勻度。此外，多孔質板可以 根據電漿生成部的密度分佈，以及擴散計算結果’來加以 設計。因此可以避免試誤法所需的大量時間及精力，且可 輕易而便利地提供多孔質板。 雖然本發明係針對本文內所揭露的結構來加以說明 的，但是並不限於本文中所述的細節，且本申請案係要涵 蓋因改良而致，或是屬於下文申請專利範圍的範疇內的修 φ 改或變化。 【圖式簡單說明】 第1圖是根據本發明第一實施例之微波電漿處理裝置 的示意圖。 第2圖是根據本發明第一實施例之多孔質板的示意 圖。 第3圖是曲線圖，用來解釋根據本發明第一實施例之 # 多孔質板的功能及效果。 第4圖是曲線圖，用來解釋根據本發明第二實施例之 多孔質板的功能及效果。 第5圖是根據本發明第三實施例之多孔質板的示意 圖。 第6圖是示意圖，用來本發明第四實施例中之槽縫的 分佈。 第7圖是根據本發明第五實施例之多孔質板的剖面 圖0 -19- 200540988 (17) 【主要元件符號說明】 1 電 漿 處 理 腔 室 2 基 體 3 基 體 承 載 台 4 多 孔 質 板 5 處 理 用 氣 體 導 入裝置 6 排 氣 □ 7 電 介 質 材 料 窗 □ 8 Μ j \ \\ 端 式 圓 形 波 導 10 冷 卻 水 通 路 11 槽 縫 -20 -200540988 (1) IX. Description of the invention [Technical field to which the invention belongs] The present invention relates to a plasma processing device, such as an etching device, a nitriding device, or an oxidation device, such as a semiconductor process applied to, for example, a semiconductor substrate or a liquid crystal substrate. In the middle. More specifically, the present invention relates to a plasma processing device, by which the amount of plasma active species or active molecules next to a substrate (object to be processed) can be made into a desired density (or concentration) and Φ distribution. situation. [Prior art] In order to improve the yield of a wafer made on a semiconductor substrate, the uniformity of the treatment on the entire surface of the semiconductor substrate in the plasma processing device is very important. In order to obtain processing uniformity on the surface of a semiconductor substrate, many attempts have been made on a plasma processing apparatus. One example is the use of porous plates. For example, Japanese Early Laid-Open Patent Application Publication No. 2000-5 8294 shows a CVD (Chemical Vapor Deposition) device in which a porous plate must be changed in order to ensure that a thin film can be deposited on a semiconductor substrate with a uniform thickness. To control the amount of reactive gas supplied to various points on the surface of the semiconductor substrate. The device of this conventional technique example is a CVD device in which a semiconductor substrate is processed at a relatively high pressure, and its structure is configured to control the air flow in a viscous flow pressure region. In order to form a large pressure difference between the top surface and the bottom surface of the porous plate, and to make the gas flow rate through the holes uniform, a large number of poles are provided on the porous plate -4- 200540988 (2) small diameter Φ = 0 · 1 To 1 mm holes. The thickness distribution of this porous plate is determined based on the viscous flow relationship under reference to experimental results, where the gas flow rate through the holes is proportional to the square of the depth. Although this conventional technique example is suitable for a case where a thin film is to be uniformly deposited on a semiconductor substrate, it is not suitable for a case where a semiconductor is to be processed with a lower pressure, such as etching. This is because, in one of its requirements, since the etching process is performed in a region of lower molecular flow pressure, the thickness difference is increased for the gas flow rate according to the thickness distribution of the porous plate. In the other requirement, the porous plate must be as thin as possible to effectively use the ions, and the two requirements are contradictory. An early-published patent application publication No. 1 1 to 3 50 0 1 43 shows a porous plate that can be applied to an etching apparatus. In this example, a microwave transmission window is provided on a surface opposite to the semiconductor substrate, and the plasma can be generated by the microwave. This microwave transmission window contains three windows. The top # square window is used to isolate the atmosphere and vacuum from each other. The middle and bottom windows are provided with small holes for conduction, and the reaction gas system is evenly supplied to the surface of the semiconductor substrate. This type of microwave transmission window with three windows and which can be used as a porous plate is set to make the pressure in the window high and the space between them small to prevent discharge in the window of the three window structure. This conventional technique example is based on the idea that the microwave transmission window (porous plate) can make the amount of reactive gas supplied to various points on the surface of the semiconductor substrate uniform, and that the microwave transmission window (porous plate) can A uniform microwave is formed at the bottom, and the amount of plasma ions-5-200540988 (3) supplied to each point on the surface of the semiconductor substrate becomes uniform. In addition, a slot antenna with holes is provided to form a uniform plasma at the bottom of the microwave transmission window, so that the microwave transmission distribution can be made substantially uniform. However, if the slot antenna is designed to provide a substantially uniform microwave transmission distribution, although this can form a uniform microwave plasma at the bottom of the microwave transmission window under particularly restricted conditions, under other conditions, It will not easily form a uniform microwave plasma there. Presumably this is because φ is a microwave mode that changes with the density of the plasma, so the plasma cannot be excited stably. Another example is disclosed in Japanese Early Laid-Open Patent Application Publication No. 5-3 45 9 82, in which the microwave surface interference wave is formed between the slots and can cause no mode jump (M ode J ump) In the case, the microwave plasma is excited stably. In this example of conventional technology, because diffusion is applied in the region of molecular flow pressure to create a uniform plasma distribution near the semiconductor substrate, the size of the plasma processing chamber and the plasma processing device will tend to become larger. . Therefore, there have been attempts to use a porous plate to uniformize the plasma distribution near the substrate while reducing the size of the plasma processing apparatus. However, although a porous plate having, for example, an irregular distribution and small holes having a diameter of several millimeters is used, it can make the plasma distribution around the substrate uniform, but the contact area between the plasma and the porous plate will be Increase, and the plasma density will be significantly reduced. This will result in longer substrate processing time. On the other hand, although larger holes can be used to reduce the contact area with the plasma to suppress the reduction of the plasma, the effect of each hole will become larger, so it takes a lot of time and effort to use trial and error law. So this is not true -6-200540988 (4). [Summary of the Invention] Therefore, an object of the present invention is to provide a plasma processing apparatus', by which a plasma active species can be adjusted to a desired density (concentration) and distribution by being positioned beside an object to be processed. Another object of the present invention is to provide a plasma processing apparatus having a porous plate disposed therein, which can effectively make the plasma distribution next to the object to be processed uniform, and at the same time, it can be very easy without relying on trials. Mistakes can suppress the decrease in plasma density. According to an aspect of the present invention, in order to achieve at least one of the foregoing objectives, a plasma processing apparatus is provided, including: a plasma generating section; and a porous plate disposed between the plasma generating section and a Between the objects to be processed, the porous plate has a plurality of holes, and the system is made non-uniform in terms of at least one of factors such as shape, size, and distribution. Φ According to another aspect of the present invention, a plasma processing apparatus is provided, including: a plasma generating section; and a porous plate disposed between the plasma generating section and an object to be processed, wherein The porous plate has multiple holes, and their shapes and distributions are determined according to the distribution of the active species and the calculation results of the diffusion in the plasma generating part. Therefore, the plasma active species next to the object within 5 miles will be It has a desired concentration and distribution. According to yet another aspect of the present invention, it provides a circuit for designing a circuit having a plasma generating section and a porous plate between the plasma generating section and an object to be processed. The method for a pulp processing device includes the following steps: The shape and distribution of the holes in the porous plate are determined according to the calculation results of the distribution and diffusion of active species in the pulp generation unit. The adjacent plasma-active species have the required concentration and distribution. In short, according to the present invention, a porous plate is used. The holes in the porous plate are non-uniform in terms of shape, size, and distribution, and can provide various plasma-active species with different densities and distributions. . In detail, the shape, size, and distribution of these pores are determined based on calculation results of the distribution and diffusion of the active species φ in the plasma generation section. This can effectively avoid a lot of time and effort required for trial and error, and can easily and conveniently obtain a porous plate that can ensure the density and distribution of the required plasma active species. These and other objects, features, and advantages of the present invention will be more clearly understood from the following description of the preferred embodiments of the present invention and the accompanying drawings. # [Embodiment] A plasma processing apparatus according to a preferred embodiment of the present invention includes a plasma processing section and a porous plate disposed between the plasma processing section and a substrate to be processed, wherein the porous The shape and distribution of the holes on the plate are determined according to the calculation results of the density distribution and diffusion of the active species in the plasma generation section to ensure that the plasma active species next to the substrate will have a uniform distribution. According to this embodiment, the porous plate is designed based on the calculation results of the density distribution and diffusion of the active species in the plasma generating section. Therefore, large diameter holes can be designed without relying on trial and error operations. Therefore, 200540988 (6) a plasma treatment device can be provided which can provide a plasma active species distribution with good uniformity beside the substrate, while suppressing electricity Reduction of pulp. Here, the density distribution of the active species in the plasma generating section can be detected using, for example, an electronic probe. In addition, the results of the diffusion calculations can be made using the following equation (1) called the two-carrier diffusion equation. It is known that the plasma that reaches a wall by diffusion will be destroyed by the Compound Quenching effect on the wall, and its amount can be expressed by the following equation (2). The diffusion coefficient and the like required to calculate these equations can be determined based on experiments performed using an electron probe. Q = DxAN / LxS ... (1) In equation (1), Q is the diffusion amount, D is the diffusion coefficient, AN is the density difference, L is the length, and S is the area. Q, = NxCxS ... (2) In equation (2), Q 'is the amount of compound quenching, N is the plasma density, C is the coefficient, and S is the area. Based on these calculation formulas and the density distribution in the plasma generating section, it is possible to determine the area and the distribution of holes so that the plasma density near the substrate becomes uniform. According to the result of such a design, the holes located in or near the area with a higher plasma generation density will have a smaller diameter, while the holes located in or near the area with a lower plasma generation density will have a smaller diameter Larger diameter. -9- 200540988 (7) The thickness of the porous plate is made thinner around the hole with a larger cross-sectional area to further reduce the composite quenching of the plasma on the hole wall, and has a relatively small Holes with small cross-sections must be increased to maintain overall balance. This can provide a plasma processing apparatus in which the plasma throughput can be increased, but the uniformity of the plasma distribution beside the substrate can be maintained. The porous plate can be made of a material whose thermal expansion coefficient is slightly less than ΐχΐ (Γ5 / ° c), and in this case, it can be suppressed when the porous plate rises to 5 00 ° C due to the temperature of the plasma φ process. The resulting shape change. Therefore, this can provide a plasma treatment device in which the distribution of plasma active species beside the substrate is stable and uniform. The diameter of the pores on this porous plate is approximately 1 mm to 5 In the range of 0 mm, it must have a processing accuracy of about 0.1 mm. This porous board is used at a temperature below about 500 ° C. Therefore, through simple calculations, its thermal expansion coefficient is the best Is less than about Ixl0_5 / ° C. More preferably, it is made of a material with a coefficient of thermal expansion less than ΐχΐ〇_6 / ° C, such as quartz, which is a ceramic material containing silicon. Φ All of the porous plate The cross-sectional area of the pores can be enlarged or reduced at approximately the same ratio. This can provide a plasma treatment device, which can easily and conveniently change the density of the plasma active species next to the substrate to be treated without changing the substrate. The distribution of plasma-active species on the edge. This can be achieved because the amount of plasma passing through the holes in the porous plate by diffusion is approximately proportional to the total cross-sectional area of all the holes in the porous plate. The porous plate can be made so that the center of the hole on it is arranged along the coaxial and concentric circle, and the hole located along the same circle is -10- 200540988 (8) The hole has approximately the same cross section. Area. This can provide a plasma processing device, which can be used for precise and uniform plasma processing of circular substrates with similar central symmetry, such as semiconductor substrates. This porous plate can be made with The holes are approximately equidistantly arranged in the center. This can provide a plasma treatment device, through which the entire surface of the substrate can be uniformly treated with plasma. The cross-sectional area of the holes in this porous plate can be slightly increased to ensure the substrate. The active species next to the φ body will contain ions. This provides a plasma treatment device where ions will be the main reaction factor, like the etching process or nitriding process The porous cross-sectional area of this porous plate can be slightly reduced to ensure that the active species next to the substrate will contain neutral radicals. This can provide a plasma processing device that can be performed without causing significant semiconductor performance The degraded plasma processing process is similar to the oxidation process using oxygen radicals as the main component. Φ This plasma processing device may include a plasma processing chamber with a dielectric member for transmitting microwaves and introducing microwaves into the plasma processing device. A microwave introduction device in a plasma processing chamber, a substrate, and a porous plate disposed between the substrate and the dielectric member, the device is configured to excite a surface wave plasma due to microwaves. This can provide an electricity The slurry processing device allows the plasma generation section to be formed locally next to the dielectric member, and the porous plate can be accurately and simply designed. In this microwave plasma processing apparatus, the 'microwave' is confined to the dielectric member by the plasma generated by the microwave. Therefore, one of its characteristics is that the plasma will only be generated next to the dielectric member-11-200540988 (9) and transmitted toward the base 2 by diffusion. Therefore, according to the distribution and diffusion of the plasma generating portion, it is possible to design the holes of the porous plate and the distribution thereof with good accuracy. The introduction of microwaves into the plasma processing chamber can be accomplished by using an endless circular waveguide with a slot. This can provide a plasma processing device, by which the density distribution of the plasma generating section is relatively unaffected by the conditions of the plasma processing, such as the gas pressure and the type of gas used, etc. A single porous plate is used under a variety of different plasma treatment conditions. In the present invention, it is not necessary to provide holes on the porous plate distributed along the same axis and concentric circles. They can be set in any desired way. In addition, the shape of the hole is not limited to a circle. Any shape can be used, such as rectangular, triangular, or star (pentagram). The porous plate of the present invention can be applied to any type of plasma processing apparatus, as long as the plasma generating section exists only in a local area. For example, it can be a microwave plasma or an inductively coupled plasma (ICP). Φ The preferred embodiments of the present invention will be described below with reference to the drawings. [Embodiment 1] The first embodiment of the present invention will be described in detail with reference to an example of a microwave plasma processing apparatus shown in Fig. 1 of the drawings. In Fig. 1, a cylindrical plasma processing chamber is indicated by reference numeral 1 and a substrate to be processed is indicated by reference numeral 2. Denoted by reference number 3 is a substrate carrying platform for carrying the substrate 2 thereon. The porous plate is marked with the reference number 4 and the processing plate is marked with the reference number 5 -12-200540988 (10) Gas introduction device. Reference numeral 6 indicates an exhaust port, and reference numeral 8 indicates an endless circular waveguide with a slot for introducing microwaves into the plasma processing chamber 1. Denoted by reference numeral 11 are slots, which are arranged on the circular waveguide 8 and have a pitch corresponding to half or a quarter of the wavelength of the microwaves in the tube. Reference numeral 7 indicates a dielectric material window for introducing microwaves into the plasma processing device, and reference numeral 10 indicates a cooling water passage provided in the waveguide 8 φ. The inner walls of the plasma processing chamber 1 and the dielectric material window 7 are made of quartz, which does not cause metal pollution to the substrate 2. The semiconductor stage 3 is made of a ceramic material having a nitride inscription as a main component. The porous plate 4 is made of quartz material with a thermal expansion coefficient of 5xl (T7 / ° C (almost never expands due to heat)) and does not cause metal pollution. The cross-sectional area of each hole and its distribution are based on the The density distribution and the diffusion result of the plasma generating part next to the dielectric material window 7 are designed. For the holes on the porous plate, the center symmetry of the waveguide 8 and the cylindrical plasma φ processing chamber 1 For consideration, as shown in Figure 2, these holes are made cylindrical, and they are arranged at the center and distributed at approximately equal distances along some concentric circles. In addition, considering the same Under central symmetry, these holes located along one or more circles must have approximately the same cross-sectional area. The distance between adjacent holes is approximately equal to 20 mm. The diameter of the holes is approximately 10-20 In the range of millimeters, the ratio of the total cross-sectional area of all the holes to the cross-sectional area of the plasma processing chamber 1 (hereinafter referred to as "opening ratio") is approximately equal to 0.2. The plasma using this embodiment will now be described Processing device -13- 200540988 on substrate 2 (11) An example of nitriding treatment. First, a silicon substrate with a 2 nm thick oxide film formed on the surface is transferred to a substrate carrier 3 by a conveying device (not shown), and then Place it on the table. Then, the plasma processing chamber 1 is evacuated to an extent of not more than 0.1 Pa by an exhaust system (not shown). Then, 500 seem of nitrogen is passed through the processing gas introduction device 5 Injection into the plasma processing chamber 1. Thereafter, a conductance valve provided in the exhaust system was adjusted to maintain the processing chamber 1 at Φ 130 Pa. Next, a microwave voltage source was started to pass through the endless circle The shaped waveguide 8 and the dielectric material window 7 supply 1.5 kW of microwaves into the plasma processing chamber 1 to generate plasma in the plasma processing chamber 1. When the plasma density excited by the microwave becomes greater than about 1 × l. ] 1cm3, microwave can no longer enter the plasma, so the plasma will only be generated on the polar surface of the dielectric material window 7 (Polar Surface). Nitrogen ions in the plasma will move forward and then reach Porous plate One part of them will disappear due to compound quenching on the surface of the porous plate, but another part will be formed on the surface of the substrate 2 through the holes in the multi # porous plate 4 and adjusted by them Uniform distribution of nitrogen ions, and these ions will reach the surface of the substrate 2. The nitrogen ions moving closer to the substrate 2 will be accelerated by the action of an ion sheath formed on the surface of the substrate 2 to be treated, Therefore, they will be incident on the substrate 2 and cause nitridation of the silicon oxide film. Three minutes after the microwave supply is started, the microwave voltage source is stopped and the nitrogen supply is interrupted. The plasma processing chamber 1 is evacuated to no After the degree is greater than 0.1 Pa, the substrate 2 is taken out from the plasma processing chamber 1. After the nitriding process is completed, an ellipsometer (KLA_Tencor -14-200540988 (12)) is used to measure the thickness increase of the silicon nitride film converted from the silicon oxide film on the surface of the substrate 2. The result was 2.1 nm ± 2%. This porous plate can achieve about six times higher uniformity, as seen in Section 3. As described above, according to the plasma processing apparatus of this embodiment, a porous plate with a larger diameter hole can also have a uniformity on the surface of the substrate. In addition, by designing the porous plate based on the calculation result of the density distribution φ of the plasma generating section, it can avoid a lot of time and effort required for use. This makes it easy and convenient for perforated plates. [Embodiment 2] In this embodiment, the microwave plasma-treated porous plate 4 in the first embodiment is subjected to nitriding treatment from a porous plate having an aperture ratio of about 0.1, which is the same as that in the first embodiment. The method is applied on φ. Each hole product on the porous plate 4 used in this second embodiment is a hole in the porous plate used in the first embodiment. The diameter of this hole is 1 / 10,000 (square root of 2). It's in the millimeter range. The distribution of holes in this porous plate 4 is the first embodiment. After the nitriding process is completed, an ellipsometer (KLA · company) is used to measure the thickness increase of the silicon nitride film converted from the silicon oxide film on the surface of the substrate 2. The result was I n m + 2%. Oxidation of the thickness of the thin film on the substrate 2 which has been subjected to the nitriding treatment according to the embodiment can be replaced by a multi-device generation provided by processing and diffusion errors, and the cross section of the substrate 2 is half. Since 7 to 15 are similar to Tencor's oxidized second cloth, compared with the obtained in an example of -15-200540988 (13) 'as shown in Figure 4', it can be seen that the shape of the distribution is similar 'But in the second embodiment' the thickness of the film is only about half. As mentioned earlier, it can be seen that 'the cross-sectional area of all holes on the porous board can be increased or reduced by about the same ratio', and after doing so, it will get a plasma treatment device, which can be very convenient. Increasing or decreasing the thickness of the nitride film while maintaining the uniformity of the nitriding treatment results [Example 3] In this example, the porous plate 4 shown in FIG. 5 is used instead of the first embodiment The porous plate 4 of the microwave plasma processing apparatus of the example is subjected to a nitriding treatment on the substrate 2 in the same manner as in the first embodiment. With regard to the holes in the porous plate 4 used in this third embodiment, the holes in the porous plate used in the first embodiment at the first concentric circle from the center were removed, and On the other hand, the size of the central hole is increased. In addition, the aperture ratio is approximately equal to 0.22. Since the holes on the first concentric circle from the center have been removed, even if the aperture ratio is enlarged to about 0.22, it can still ensure that there is sufficient spacing between adjacent holes. Therefore, the porous plate can have sufficient mechanical strength. After the nitriding process is completed, an ellipsometer (KLA-Tencor) is used to measure the thickness increase of the silicon oxide nitride film converted from the silicon oxide film on the surface of the substrate 2. The result was 2.2% soil 2%. Compared with the first embodiment, the film thickness was increased by about 10%. -16- 200540988 (14) As mentioned before, the spacing between adjacent coaxial and concentric circles on a porous plate can be changed moderately. 'This can provide a plasma treatment device' which can be kept sufficiently between holes The pitch can increase the aperture ratio while still maintaining the strength of the porous plate, and the processing speed can be improved. [Embodiment 4] φ In this embodiment, the slot in the microwave plasma processing apparatus of the first embodiment is changed into an arc shape, as shown in FIG. 6, and the porous plate 4 is also cut by the aperture ratio. Instead of 0.3, this corresponds to the density distribution of the plasma generating section to be generated by these slots. The nitriding treatment is performed in the same manner as in the first embodiment. According to the porous plate 4 used in this fourth embodiment, the aperture ratio can be increased by about 50% in comparison with the first embodiment. This is because, in the slot distribution according to the first embodiment, since the density distribution of the plasma generating section has a ring shape, the aperture ratio φ is set so as not to be in the center hole of the porous plate and adjacent holes. However, according to this fourth embodiment, since the density distribution of the plasma generating portion is spread uniformly over the entire surface of the dielectric material window 7, the diameter of the holes will be more uniform, and there will be almost no occurrence between adjacent holes. put one's oar in. Therefore, the aperture ratio can be increased. After the nitriding process is completed, an ellipsometer (KLA-Tencor) is used to measure the thickness increase of the silicon oxide nitride film converted from the sand oxide film on the surface of the substrate 2. As a result, the film thickness was increased by about 50% as compared with the first embodiment. -17- 200540988 (15) As mentioned above, it can use the slot distribution that can cause a more uniform density distribution of the plasma generation section. This can provide a plasma treatment device, with which the aperture ratio can be increased, and Processing speed can be increased. [Fifth Embodiment] In this embodiment, the porous plate 4 in the microwave plasma processing apparatus of the first embodiment is replaced by an aperture ratio of about 0.21, and the nitriding treatment φ is given by the first An embodiment is performed on the base body 2 in the same manner. In this fifth embodiment, the area surrounding the larger-diameter hole on the porous plate is made thinner, as shown in FIG. Therefore, the plasma composite quenching on the wall of the hole can be reduced. Since the diameter of the smaller-diameter holes is increased to maintain the overall balance, the aperture ratio of the porous plate 4 is increased. After the nitriding process is completed, an ellipsometer (KLA-Tencor) is used to measure the thickness of the silicon nitride film on the surface of the substrate 2 converted from the silicon oxide film. The result was 2.2 nm ± 2%. Compared with the first embodiment, the thickness of the film is increased by about 10%. As mentioned earlier, the thickness of the area surrounding the larger diameter holes on the porous plate is made thinner, which can provide a plasma processing device by which the smaller diameter holes can be enlarged in diameter , And the processing speed can be increased by it. According to the embodiment of the present invention described above, a porous plate with a large hole diameter is used to reduce the contact between the plasma and the hole wall portion, and to suppress the plasma composite quenching. Therefore, the processing time of the substrate can be shortened, and at the same time -18- 200540988 (16) can ensure the uniformity of the processing on the surface of the substrate. In addition, the porous plate can be designed based on the density distribution of the plasma generating section and the result of the diffusion calculation '. Therefore, a lot of time and effort required for trial and error can be avoided, and a porous plate can be provided easily and conveniently. Although the present invention is described with respect to the structure disclosed herein, it is not limited to the details described herein, and this application is intended to cover improvements resulting from or included within the scope of the patent application below Modify or change. [Brief description of the drawings] Fig. 1 is a schematic diagram of a microwave plasma processing apparatus according to a first embodiment of the present invention. Fig. 2 is a schematic view of a porous plate according to a first embodiment of the present invention. Fig. 3 is a graph for explaining functions and effects of the # porous plate according to the first embodiment of the present invention. Fig. 4 is a graph for explaining functions and effects of a porous plate according to a second embodiment of the present invention. Fig. 5 is a schematic view of a porous plate according to a third embodiment of the present invention. Fig. 6 is a schematic view showing the distribution of slits in the fourth embodiment of the present invention. Fig. 7 is a cross-sectional view of a porous plate according to a fifth embodiment of the present invention. Gas introduction device 6 Exhaust □ 7 Dielectric material window □ 8 Μ j \ \\ End circular waveguide 10 Cooling water passage 11 Slot -20-