JP3919057B2 - Polishing liquid composition - Google Patents

Description

で表される構造を２つ以上有するポリアミノカルボン酸
Ｅ：無機酸
〔２〕さらに、酸化剤を含有する〔１〕記載の研磨液組成物（以下、第２研磨液組成物ともいう）、
〔３〕さらに研磨材を含有する〔１〕又は〔２〕記載の研磨液組成物（以下、第３研磨液組成物ともいう）、
〔４〕前記〔１〕〜〔３〕いずれか記載の研磨液組成物を用いて、絶縁層と金属層を有する被研磨表面を研磨し、平坦化する半導体基板の研磨方法、
〔５〕前記〔１〕〜〔３〕いずれか記載の研磨液組成物を用いて、絶縁層と金属層を有する被研磨表面を研磨し平坦化する工程を有する半導体基板の製造方法に関する。
【０００８】
【発明の実施の形態】
本発明において、前記炭素数７〜２４の脂肪族カルボン酸及び／又はその塩とエッチング剤とを併用して用いることに一つの大きな特徴があり、かかる炭素数７〜２４の脂肪族カルボン酸及び／又はその塩はエッチング速度の抑制作用を有することから、これらの化合物とエッチング剤とを含有する研磨液組成物を用いることで、実用レベルでの研磨速度を維持し、且つ金属膜の過剰なエッチングを防止することができ、ディッシング等の欠陥のない研磨表面を得ることができるという優れた効果が発現される。
【０００９】
脂肪族カルボン酸及び／又はその塩において、研磨速度を維持し、且つディッシングを抑制するという観点から、脂肪族カルボン酸及び／又はその塩の炭素数は７〜２４であるが、さらに研磨液への溶解性、低発泡性及び研磨速度を実用レベルに保ち、且つディッシング抑制の観点から、炭素数７〜２０が好ましく、７〜１６がより好ましく、７〜１２がさらに好ましく、７〜１０が特に好ましい。
【００１０】
また、脂肪族カルボン酸及び／又はその塩の炭化水素基は、飽和及び不飽和のいずれであってもよく、直鎖及び分岐鎖のいずれの基であってもよい。
【００１１】
また、脂肪族カルボン酸の塩は、アンモニウム塩、有機アミン塩、アルカリ金属塩のいずれであってもよいが、半導体の汚染防止の観点からアンモニウム塩、モノエタノールアミン塩、ジエタノールアミン塩、トリエタノールアミン塩及びトリエチルアミン塩等の有機アミン塩が好ましい。
【００１２】
これらの脂肪族カルボン酸及びその塩の具体例としては、ヘプタン酸、オクタン酸、ノナン酸、デカン酸、ラウリン酸、ミリスチン酸、パルミチン酸、ステアリン酸、エイコサン酸等の直鎖飽和脂肪族カルボン酸、ヘプテン酸、オクテン酸、デセン酸、ドデセン酸、オレイン酸等の直鎖不飽和脂肪族カルボン酸、２−メチルヘキサン酸、２−エチルヘキサン酸、３，５−ジメチルヘキサン酸、３，５，５−トリメチルヘキサン酸、イソデカン酸等の分岐鎖飽和脂肪族カルボン酸及びこれらの脂肪族カルボン酸のアンモニウム塩、有機アミン塩、アルカリ金属塩等が挙げられる。これらの中でも研磨速度とディッシング抑制の点から直鎖又は分岐鎖の飽和脂肪族カルボン酸及びそのアンモニウム塩が好ましく、研磨液への溶解性と低発泡性の点からヘプタン酸及びそのアンモニウム塩、オクタン酸及びそのアンモニウム塩、ノナン酸及びそのアンモニウム塩、デカン酸及びそのアンモニウム塩が特に好ましい。これらの炭素数７〜２４の脂肪族カルボン酸及びその塩は、単独で又は２種以上を混合して使用してもよい。
【００１３】
脂肪族カルボン酸及びその塩の研磨液組成物中における配合量は、研磨速度を維持し、且つディッシングを抑制する観点から、０．０１〜３０重量％が好ましく、０．０２〜１０重量％がより好ましく、０．０３〜５重量％がさらに好ましい。
【００１４】
本発明に用いられるエッチング剤は、水媒体共存下で、金属、特に銅を溶解、エッチングするものであり、下記のエッチング試験Ａより得られるエッチング速度ａが３Å／ｍｉｎ以上の化合物である。即ち、エッチング試験Ａは、まず、長さ１００ｍｍの銅リボン（（株）ニラコ製：厚み０．１０ｍｍ、幅６ｍｍ）を用意し、表面の汚れ等を紙で拭きとった後、ノルマルヘキサンに浸した状態で超音波洗浄を１分間行い、十分に脱脂し、乾燥させる。その後リボン全面に研磨液が浸漬するようにその金属試験片を、螺旋状に巻き、試験前の金属試験片とし、精密天秤により、浸漬前重量を測定する。
【００１５】
次に、エッチング剤を２重量％水溶液とし、さらにアンモニア水によりｐＨを８±０．５に調整したエッチング液１００ｇを１５０ｃｃのビーカー（（株）テラオカ １５０ｃｃデスカップ）に用意し、その中に前記金属試験片を２５℃で１２時間浸漬する。浸漬中はマグネティックスターラーで銅リボンがエッチング液の流れによって回転する程度に攪拌する。試験後、銅リボン表面を充分に拭き取り、再度精密天秤にて重量を測定し、試験後の重量とする。試験前後の銅リボンの重量減少から銅の膜厚減少量を換算し、それをエッチング時間で除すことによりエッチング速度ａを求める。実用的な研磨速度を得るという観点から、上記エッチング試験Ａより得られるエッチング速度ａが３Å／ｍｉｎ以上のエッチング剤が好ましく、５Å／ｍｉｎ以上のエッチング剤がより好ましく、１０Å／ｍｉｎ以上のエッチング剤がさらに好ましい。この場合のエッチング速度ａは、２つ以上のエッチング剤を併用した場合のエッチング速度であってもよい。
【００１６】
好ましいエッチング剤としては、適切なエッチング速度を有する観点から、下記Ａ〜Ｅの群から選ばれる一つ以上の化合物を含むものである。
Ａ：炭素数６以下で１〜３個のカルボキシル基を有する脂肪族有機酸
Ｂ：炭素数７〜１０で１〜４個のカルボキシル基を有する芳香族有機酸
Ｃ：炭素数６以下で１〜４個のホスホン酸基を有する有機酸
Ｄ：分子内に式（Ｉ）：
【００１７】
【化１】

【００１８】
で表される構造を２つ以上有するポリアミノカルボン酸
Ｅ：無機酸
【００１９】
具体的には、Ａの炭素数６以下で１〜３個のカルボキシル基を有する脂肪族有機酸として、ギ酸、酢酸、プロピオン酸等のモノカルボン酸；シュウ酸、マロン酸、コハク酸、グルタル酸、アジピン酸、トリカルバリル酸等の多価カルボン酸；グリコール酸、乳酸、２−ヒドロキシプロピオン酸、リンゴ酸、酒石酸、クエン酸、グルコン酸等のヒドロキシカルボン酸；グリシン、アラニン、アスパラギン酸等のアミノ酸等が挙げられる。Ｂの炭素数７〜１０で１〜４個のカルボキシル基を有する芳香族有機酸として、安息香酸、フタル酸、トリメリット酸、ピロメリット酸、マンデル酸、サリチル酸等が挙げられる。Ｃの炭素数６以下で１〜４個のホスホン酸基を有する有機酸として、メチルホスホン酸、フェニルホスホン酸等のホスホン酸；メチルホスフィン酸、フェニルホスフィン酸等のホスフィン酸；ホスホン酸メチルエステル等のホスホン酸エステル；アミノトリ（メチレンホスホン酸）、１−ヒドロキシエチリデン−１−ジホスホン酸等のアミノホスホン酸等が挙げられる。Ｄの分子内に式（Ｉ）で表される構造を２つ以上有するポリアミノカルボン酸として、エチレンジアミン四酢酸、ニトリロ三酢酸、ジエチレンジアミン五酢酸、トリエチレンテトラミン六酢酸、ヒドロキシエチルエチレンジアミン三酢酸等が挙げられる。Ｅの無機酸として、塩酸、過塩素酸、硫酸、硝酸、リン酸、ホスホン酸、ホスフィン酸等が挙げられる。これらの中でも、研磨速度の点からＡ又はＢに属する多価カルボン酸又はヒドロキシカルボン酸、Ｃに属するアミノホスホン酸、Ｄに属する分子内に式（Ｉ）で表される構造を２つ以上有するポリアミノカルボン酸、Ｅに属する塩酸、硫酸、硝酸及びリン酸が好ましく、シュウ酸、コハク酸、グリコール酸、乳酸、クエン酸、リンゴ酸、グルコン酸、フタル酸、アミノトリ（メチレンホスホン酸）、１−ヒドロキシエチリデン−１−ジホスホン酸、エチレンジアミン四酢酸、塩酸及び硫酸がさらに好ましい。これらのエッチング剤は単独で又は２種類以上を混合して用いても良い。
【００２０】
なお、これらエッチング剤のエッチング速度ａは、例えば、グリコール酸：６０Å／ｍｉｎ、クエン酸：２５Å／ｍｉｎ、フタル酸：５０Å／ｍｉｎ、アミノトリ（メチレンホスホン酸）：１０Å／ｍｉｎ、エチレンジアミン四酢酸：３０Å／ｍｉｎ、酢酸：７０Å／ｍｉｎ、グリシン：４０Å／ｍｉｎ、塩酸：４００Å／ｍｉｎ、硫酸：１００Å／ｍｉｎである。又、炭素数７〜２４の脂肪族カルボン酸のエッチング速度ａは２Å／ｍｉｎ以下であり、エッチング剤と比べ、エッチング力がないかほとんど認められないものである。
【００２１】
本発明に用いられるエッチング剤は、さらに酸化剤、砥粒等が共存する研磨液組成物（但し、炭素数７〜２４の脂肪族カルボン酸及び／又はその塩を含有しない組成物）に調製した際に、下記のエッチング試験Ｂより得られる研磨液組成物のエッチング速度ｂが２０Å／ｍｉｎ以上となるように、その種類、含有量等を調整することが好ましい。即ち、エッチング試験Ｂは、エッチング試験Ａのエッチング液として、水、研磨材及びエッチング剤、要すればさらに酸化剤を含む研磨液組成物を用いて、室温（２５℃）２時間浸漬すること以外はエッチング試験Ａと全く同一の操作で行う。エッチング試験Ｂによって求めたエッチング速度をエッチング速度ｂとする。実用的な研磨速度を得るという観点から、上記エッチング試験Ｂより得られるエッチング速度ｂは２０Å／ｍｉｎ以上が好ましく、３０Å／ｍｉｎ以上がより好ましく、５０Å／ｍｉｎ以上がさらに好ましい。この場合のエッチング速度ｂは、２つ以上のエッチング剤を併用した研磨液組成物のエッチング速度であってもよい。
【００２２】
本発明において、かかるエッチング剤を用いることで、金属層を構成する各種金属、特に銅と錯体を形成し又は結合し、水溶性の塩及び／又はキレート化合物として表面からの除去を容易にし、研磨の際に、金属層の研磨速度を向上させる効果が発現される。
【００２３】
エッチング剤の研磨液組成物中における配合量は、金属層の除去のために実用レベルでの研磨速度を確保し、且つ金属層の過剰なエッチングを防ぐために種々選択することができ、好ましくは０．１〜１０重量％、より好ましくは０．２〜８重量％、さらに好ましくは０．３〜５重量％である。
【００２４】
本発明に用いられる水は、媒体として用いられるものである。その配合量は、被研磨物を効率よく研磨できる観点から、研磨液組成物中において、好ましくは６０〜９９．８９重量％、より好ましくは７０〜９９．４重量％、さらに好ましくは８０〜９９．０重量％である。
【００２５】
かかる組成を有する本発明の第１研磨液組成物のｐＨは、研磨速度を実用レベルに保ち、且つディッシング抑制の観点及び表面の微細なスクラッチ傷を除去する観点から、１０以下が好ましく、２〜９．５がより好ましく、４〜９がさらに好ましく、７〜９が特に好ましい。ｐＨを前記範囲内に調整するためには、必要に応じて、硝酸、硫酸等の無機酸、有機酸、水酸化カリウム、水酸化ナトリウム、アンモニア、有機アミン等の塩基性物質を適時配合することができる。
【００２６】
本発明の第２研磨液組成物は、第１研磨液組成物に酸化剤がさらに配合されたものである。本発明に用いられる酸化剤は、金属を酸化させるものである。本発明においては、かかる酸化剤を用いることにより、金属層を酸化させ、金属層の機械的研磨効果を促進させる効果又はエッチング剤による銅の溶解を促進させる効果が発現されると考えられる。
【００２７】
酸化剤としては、過酸化物、過マンガン酸又はその塩、クロム酸又はその塩、硝酸又はその塩、ペルオクソ酸又はその塩、酸素酸又はその塩、金属塩類、硫酸類等が挙げられる。
【００２８】
その具体例として、過酸化物としては、過酸化水素、過酸化ナトリウム、過酸化バリウム等；過マンガン酸又はその塩としては、過マンガン酸カリウム等；クロム酸又はその塩としては、クロム酸金属塩、重クロム酸金属塩等；硝酸塩としては、硝酸鉄（III)、硝酸アンモニウム等；ペルオクソ酸又はその塩としては、ペルオクソ二硫酸、ペルオクソ二硫酸アンモニウム、ペルオクソ二硫酸金属塩、ペルオクソリン酸、ペルオクソ硫酸、ペルオクソホウ酸ナトリウム、過ギ酸、過酢酸、過安息香酸、過フタル酸等；酸素酸又はその塩としては、次亜塩素酸、次亜臭素酸、次亜ヨウ素酸、塩素酸、臭素酸、ヨウ素酸、過塩素酸、次亜塩素酸ナトリウム、次亜塩素酸カルシウム等；金属塩類としては、塩化鉄 (III)、硫酸鉄 (III)、クエン酸鉄（III)、硫酸アンモニウム鉄（III)等が挙げられる。好ましい酸化剤としては、過酸化水素、硝酸鉄（III)、過酢酸、ペルオクソ二硫酸アンモニウム、硫酸鉄（III)及び硫酸アンモニウム鉄（III)が挙げられ、特に、半導体の汚染防止の観点から過酸化水素が好ましい。これらの酸化剤は、単独で又は２種以上を混合して使用してもよい。
【００２９】
酸化剤は、第２研磨液組成物中において水を媒体とした状態で使用される。該酸化剤の第２研磨液組成物中における配合量は、金属層の迅速な酸化により、実用レベルの研磨速度を得る観点から、好ましくは０．１〜６０重量％、より好ましくは０．２〜５０重量％、さらに好ましくは０．３〜３０重量％、特に好ましくは０．３〜１０重量％である。
【００３０】
また、第２研磨液組成物における炭素数７〜２４の脂肪族カルボン酸及び／又はその塩の配合量は、好ましくは０．０１〜３０重量％、より好ましくは０．０２〜１０重量％、さらに好ましくは０．０３〜５重量％である。エッチング剤の配合量は、好ましくは０．１〜１０重量％、より好ましくは０．２〜８重量％、さらに好ましくは０．３〜５重量％である。水の配合量は、好ましくは３９．８９〜９９．７９重量％、より好ましくは７０〜９９．４重量％、さらに好ましくは８０〜９９重量％である。かかる組成を有する第２研磨液組成物のｐＨは、第１研磨液組成物と同様、研磨速度を実用レベルに保ち、且つディッシング抑制の観点及び表面の微細なスクラッチ傷を除去する観点から、１０以下が好ましく、２〜９．５がより好ましく、４〜９がさらに好ましく、７〜９が特に好ましい。ｐＨを前記範囲内に調整するためには、必要に応じて、硝酸、硫酸等の無機酸、有機酸、水酸化カリウム、水酸化ナトリウム、アンモニア、有機アミン等の塩基性物質を適時配合することができる。
【００３１】
本発明の第１及び第２研磨液組成物は、固定砥石、パッド中に砥粒を固定した研磨パッド等を用いる研磨方式において有効である。例えば、固定砥石による研磨方式の研磨中に本発明の第１及び第２の研磨液組成物を使用することにより、研磨速度を維持し、且つ金属層のディッシングを抑制することができる。
【００３２】
本発明の第３研磨液組成物は、第１又は第２研磨液組成物に研磨材をさらに含有させたものであり、遊離研磨材による研磨方式に用いられるものである。
【００３３】
研磨材としては、研磨用に一般に使用される研磨材を使用することができ、例えば、金属、金属又は半金属の炭化物、金属又は半金属の窒化物、金属又は半金属の酸化物、金属又は半金属のホウ化物、ダイヤモンド等が挙げられる。金属又は半金属元素は周期律表の３Ａ、４Ａ、５Ａ、３Ｂ、４Ｂ、５Ｂ、６Ｂ、７Ｂ又は８Ｂ族に属するものが挙げられる。その例としては、二酸化ケイ素、酸化アルミニウム、酸化セリウム、酸化チタン、酸化ジルコニウム、窒化ケイ素、二酸化マンガン、炭化ケイ素、酸化亜鉛、ダイヤモンド及び酸化マグネシウムが挙げられる。これらの中では、二酸化ケイ素、酸化アルミニウム及び酸化セリウムが好ましく、この具体例として、二酸化ケイ素としては、コロイダルシリカ粒子、フュームドシリカ粒子、表面修飾したシリカ粒子等；酸化アルミニウムとしては、α―アルミナ粒子、γ―アルミナ粒子、δ―アルミナ粒子、θ―アルミナ粒子、η―アルミナ粒子、無定型アルミナ粒子、その他の製造法の異なるフュームドアルミナやコロイダルアルミナ等；酸化セリウムとしては、酸化数が３価又は４価のもの、結晶系が、六方晶系、等軸晶系又は面心立方晶系のもの等が挙げられる。特に好ましくは二酸化ケイ素である。これらの研磨材は、単独で又は２種以上を混合して用いてもよい。
【００３４】
かかる研磨材の一次粒子の平均粒径は、好ましくは５〜１０００nm、より好ましくは１０〜５００nm、さらに好ましくは２０〜３００nm、特に好ましくは５０nm〜２００nm、最も好ましくは５０〜１００nmである。該平均粒径の下限は、一定の研磨速度を維持する観点から、５nm以上が好ましく、また、その上限は、被研磨物の表面に引っ掻き傷（スクラッチ）を発生させない観点から、１０００nm以下が好ましい。
【００３５】
特に研磨材として二酸化ケイ素を用いた場合には、研磨速度を向上させる観点から、１次粒子の平均粒径は、５nm以上、好ましくは１０nm以上、より好ましくは２０nm以上である。
【００３６】
なお、研磨材の一次粒子の平均粒径は、０．１％ポリスチレンスルフォン酸ソーダ水溶液１００ｇに該研磨材０．１ｇを加え、次いで超音波を印加し該研磨材を分散させたものを透過型電子顕微鏡で観察して画像解析により求められる。
【００３７】
第３研磨液組成物を半導体装置の配線形成の際に用いる場合、特に好ましく用いられる研磨材は、純度が好ましくは９８重量％以上、より好ましくは９９重量％以上、特に好ましくは９９．９重量％以上のシリカ粒子である。かかる研磨材としては、四塩化ケイ素等の揮発性ケイ素化合物を酸水素焔中での高温加水分解により製造されるフュームドシリカ、又はケイ酸アルカリやケイ酸エチルを出発原料とする製法で得られるコロイダルシリカが挙げられる。
【００３８】
なお、前記研磨材の純度は、次のようにして求められる。即ち、研磨材１〜３ｇを酸又はアルカリ水溶液に溶かし、ＩＣＰ（プラズマ発光分析）法により、ケイ素イオンを定量することにより測定することができる。
【００３９】
かかる研磨材は、第３研磨液組成物中において水を媒体とした、いわゆるスラリー状態で使用される。研磨材の第３研磨液組成物中における配合量は、本発明の研磨液組成物の粘度や被研磨物の要求品質等に応じて種々選択することができ、０．０１〜３０重量％が好ましく、０．１〜２０重量％がより好ましく、１．０〜１０重量％がさらに好ましい。
【００４０】
炭素数７〜２４の脂肪族カルボン酸及び／又はその塩の第３研磨液組成物中における配合量は、研磨速度を維持し、且つディッシングを抑制する観点から、０．０１〜３０重量％が好ましく、０．０２〜１０重量％がより好ましく、０．０３〜５重量％がさらに好ましい。
【００４１】
エッチング剤の第３研磨液組成物中における配合量は、金属層除去のために実用レベルの研磨速度を確保し、且つ金属層の過剰なエッチングを防ぐために種々選択することができ、例えば、好ましくは０．１〜１０重量％、より好ましくは０．２〜８重量％、さらに好ましくは０．３〜５重量％である。
【００４２】
酸化剤の第３研磨液組成物中における配合量は、金属層の迅速な酸化により、実用レベルの研磨速度を得る観点から、好ましくは０．１〜６０重量％、より好ましくは０．２〜５０重量％、さらに好ましくは０．３〜３０重量％、特に好ましくは０．３〜１０重量％である。
【００４３】
また、第３研磨液組成物における水の配合量は、好ましくは３９．８８〜９９．８９重量％、より好ましくは６０〜９９．４重量％、さらに好ましくは７５〜９９重量％である。かかる組成を有する第３研磨液組成物のｐＨは、第１研磨液組成物と同様、研磨速度を実用レベルに保ち、且つディッシング抑制の観点及び表面の微細なスクラッチ傷を除去する観点から、１０以下が好ましく、２〜９．５がより好ましく、４〜９がさらに好ましく、７〜９が特に好ましい。ｐＨを前記範囲内に調整するためには、必要に応じて、硝酸、硫酸等の無機酸、有機酸、水酸化カリウム、水酸化ナトリウム、アンモニア、有機アミン等の塩基性物質を適時配合することができる。
【００４４】
本発明の第１研磨液組成物は、例えば以下のような手順により調製することができる。まず、所定量の水にエッチング剤を加え、ｐＨを所定の値に調整する。上記ｐＨ調整を行ったエッチング剤の水溶液に、予め所定のｐＨに調整した炭素数７〜２４の脂肪族カルボン酸及び／又はその塩の水溶液を所定量加え、最終的にｐＨ調整を行うことで第１研磨液組成物を得ることができる。
【００４５】
第２研磨液組成物は、例えば以下のような手順により調製することができる。まず、所定量の水にエッチング剤を加え、ｐＨを所定の値に調整する。上記ｐＨ調整を行ったエッチング剤の水溶液に、予め所定のｐＨに調整した炭素数７〜２４の脂肪族カルボン酸及び／又はその塩の水溶液を所定量加える。研磨前に酸化剤を加え、最終的にｐＨの調整を行うことで第２研磨液組成物を得ることができる。
【００４６】
第３研磨液組成物は、例えば以下のような手順により調製することができる。まず、所定量の水にエッチング剤を加え、ｐＨを所定の値に調整する。上記ｐＨ調整を行ったエッチング剤の水溶液に、所定量の研磨材を加え、研磨材が均一に分散するよう十分に撹拌する。さらに予め所定のｐＨに調整した炭素数７〜２４の脂肪族カルボン酸及び／又はその塩の水溶液を所定量加え、必要に応じて研磨前に所定量の酸化剤を添加し、最終的にｐＨ調整を行うことで、第３研磨液組成物を得ることができる。
【００４７】
また、第１〜第３研磨液組成物には、各種界面活性剤、分散安定化剤等の上記以外の研磨助剤を加えてもよい。
【００４８】
本発明の研磨液組成物は、絶縁層と金属層を有する表面を研磨の対象とし、メタルＣＭＰに好適に用いられる。金属層を形成する金属としては、銅又は銅合金、アルミニウム又はアルミニウム合金、タングステン等が挙げられる。これらの中では、特に半導体基板上の埋め込み金属配線形成工程に用いる場合、銅又は銅合金が好ましい。かかる銅又は銅合金の金属配線層の形成に、本発明の研磨液組成物を用いると、研磨速度を維持し、且つ埋め込み金属配線層のディッシングを抑制する効果が特に顕著に発現される。また、絶縁層を形成する材としては、有機、無機いずれの材を用いてもよく、二酸化ケイ素、フッ素添加二酸化ケイ素、水素含有ＳＯＧ（スピンオングラス）、窒化物（例えば、窒化タンタル、窒化チタン等）等の無機系の材、有機ＳＯＧ、ポリイミド、フッ素化ポリイミド、メチルポリシロキサン、芳香族ポリエーテル、ハイドロジェンシルセスキオキサン、フルオロカーボン等の有機系の材が挙げられる。
【００４９】
これらの被研磨物の形状は、半導体基板上の絶縁膜表面に配線形状の溝を形成し、該溝を含む絶縁膜上に金属が堆積した形状であることが好ましい。また、絶縁膜と金属層の間にタンタル、チタン又はそれらの窒化物からなるバリア膜が設けられてもよい。特に金属層が銅又は銅合金である場合、前記バリア膜を設けることにより、絶縁層への銅の拡散を防止できるため好ましい。
【００５０】
本発明の第１及び第２研磨液組成物は固定砥石、パッド中に砥石を固定した研磨パッド等を用いる研磨方式において有効であり、第３の研磨液組成物は通常のウレタン製の研磨パッドを用いる遊離研磨材による研磨方式において有効であるが、固定砥石、パッド中に砥石を固定した研磨パッド等を用いる研磨方式においても有効である。
【００５１】
本発明の絶縁層と金属層を有する被研磨表面の研磨方法は、本発明の研磨液組成物を用いて半導体基板を研磨し、平坦化する工程を有する。
【００５２】
また、本発明の半導体基板の製造方法は、本発明の研磨液組成物を用い、絶縁層と金属層を有する半導体表面を研磨することにより、金属層の研磨速度を維持し、且つ埋め込み金属配線層のディッシングを抑制できるため、半導体基板の製造に好適に用いることができる。
【００５３】
【実施例】
実施例１〜１２及び比較例１〜１２
所定量の水に表１〜２に示すエッチング剤、過酸化水素をそれぞれ表１〜２に示す組成になるように混合し、さらに表１〜２に示した研磨材５重量％分を混合、攪拌した後、混合液のｐＨが７．５〜８になるようにアンモニア水を加える。これとは別に、予め表１〜２に示す炭素数７〜２４の脂肪族カルボン酸にアンモニア水を加えｐＨを７．５〜８とすることで脂肪族カルボン酸及びその塩の水溶液を調製する。この脂肪族カルボン酸及びその塩の水溶液を前記混合液に表１〜２に示す組成になるように混合し、攪拌した後、混合液のｐＨを表１〜２に示した値に調整し、研磨液組成物を得た。なお、使用した各研磨材は、フュームドシリカ（１次粒径：５０ｎｍ）、コロイダルシリカ（１次粒径：１００ｎｍ）である。また、直径５０ｍｍ、板厚１ｍｍの圧延した銅板を片面研磨機により下記の条件にて研磨した。以下、かぎ括弧内の用語は、商品名を示す。
【００５４】
＜片面加工機の設定条件＞
使用片面加工機：エンギス社製 片面加工機（定盤サイズ30cm）
加工圧力：29.4×10³ Pa
研磨パッド：上層：「IC1000」（ロデールニッタ社製）、下層：「SUBA400 」
（ロデールニッタ社製）
定盤回転数：60rpm
ワーク回転数：50rpm （定盤とワークは同一方向に回転）
研磨液組成物供給流量：100ml/min
研磨時間：10分間
【００５５】
また、相対研磨速度、相対エッチング速度、被研磨表面のディッシング、銅の表面状態等の研磨液組成物の特性を以下の方法に従って評価した。これらの結果を表１〜２に示す。
【００５６】
（相対研磨速度）
相対研磨速度とは、研磨液組成物の研磨速度をその研磨液組成物と研磨材、酸化剤及びエッチング剤の種類及び量を同一とした研磨液組成物（比較例）の研磨速度で除した値である。研磨速度は直径５０ｍｍ、板厚１ｍｍの圧延した銅板を上記研磨条件で研磨し、研磨前後の板厚変化を測定し、それを研磨時間で除することにより求めた。なお、銅板の板厚は、東京精密社製、高精度デジタル測長器「ＭＩＮＩＡＸ」を用いて測定した。実施例１〜６は比較例１を、実施例７は比較例２を、実施例８は比較例３を、実施例９は比較例４を、実施例１０は比較例５を、実施例１１は比較例１１を、実施例１２は比較例１２を、比較例９は比較例１を、比較例１０は比較例２を基準とした。なお、比較例６〜８は上記規定とは異なり、比較例１を基準として相対研磨速度を算出した。
【００５７】
（相対エッチング速度）
相対エッチング速度は、脂肪族カルボン酸及び／又はその塩を含有する研磨液組成物のエッチング速度を脂肪族カルボン酸及び／又はその塩を含有しないが研磨材、酸化剤及びエッチング剤の種類及び量を同一とした研磨液組成物のエッチング速度ｂで除した値である。実施例１〜６は比較例１を、実施例７は比較例２を、実施例８は比較例３を、実施例９は比較例４を、実施例１０は比較例５を、実施例１１は比較例１１を、実施例１２は比較例１２を、比較例９は比較例１を、比較例１０は比較例２を基準とした。なお、比較例６〜８は上記規定と異なり、比較例１を基準として相対エッチング速度を算出した。また、実施例１〜１２及び比較例７〜８の研磨液組成物のエッチング速度は、これら研磨液組成物を用いる以外は、前記エッチング試験Ｂと同じ条件下で測定された値である。
【００５８】
（ディッシング）
ディッシング評価のために、銅ダマシン配線パターン付きウエハ（ＳＫＷ社製、「SKW6-2」、サイズ：200mm ）から２０mm角のウエハチップを切り出し、ウエハチップ５枚をセラミック製の貼り付け板に固定後、上記条件で状態を確認しながら配線幅１５０μｍの銅配線部分周辺の銅膜が除去され、バリア膜が現れた時点まで研磨し、この時点まで要した研磨時間の２０％の時間でさらに研磨し、ディッシング評価用サンプルとした。ディッシングは、ウエハチップ上の配線幅１50μｍの銅配線部分の断面形状プロファイルを表面粗さ測定機（（株）ミツトヨ製「SV-600」）で測定し、評価した。なお、測定した銅配線の断面形状プロファイルに０．１５μｍ以上の凹みがない場合、ディッシング無しとし、０．１５μｍ以上の凹みがある場合、ディッシング有りとし、表１〜２中それぞれ「無」、「有」で示す。
【００５９】
（銅表面状態）
ディッシング評価に用いたウエハチップ表面の配線幅１50μｍの銅配線部分の銅膜の表面状態を光学顕微鏡で観察し、荒れの有無を確認した。
【００６０】
なお、比較例１〜６の研磨液組成物のエッチング速度ｂは以下の通りである。比較例１（５０Å／ｍｉｎ）、比較例２（１００Å／ｍｉｎ）、比較例３（２００Å／ｍｉｎ）、比較例４（６００Å／ｍｉｎ）、比較例５（５０Å／ｍｉｎ）、比較例６（１００Å／ｍｉｎ）。
【００６１】
【表１】

【００６２】
【表２】

【００６３】
表１〜２の結果から炭素数７〜２４の脂肪族カルボン酸を研磨液組成物に配合した実施例１〜１２の研磨液組成物はいずれも、配合しない比較例１〜５、１１、１２の研磨液組成物に比べて、研磨速度を実質的に低下させることなく、エッチング速度を抑制し、ディッシングが発生しないものであることがわかる。
【００６４】
また、炭素数７〜２４の脂肪族カルボン酸を用いることなく、２種類の炭素数６以下の脂肪族カルボン酸を併せて用いた比較例６の研磨液組成物はエッチング速度が高く、ディッシングが発生するものであることがわかる。
【００６５】
また、２種類の炭素数７〜２４の脂肪族カルボン酸を併せて用いた比較例７の研磨液組成物や銅と水溶性の塩を形成する有機酸を配合しない比較例８の研磨液組成物、エッチングを抑制するベンゾトリアゾールを配合した比較例９の研磨液組成物は、いずれも研磨速度が非常に低く、ポリアクリル酸アンモニウムを配合した比較例１０の研磨液組成物は銅表面に荒れが発生していることがわかる。
【００６６】
従って、炭素数７〜２４の脂肪族カルボン酸とエッチング剤を併用することにより、より高い研磨速度を実現でき、且つディッシングを防止できることがわかる。
【００６７】
特に、研磨時の泡立ちの点から炭素数７〜２４の脂肪族カルボン酸としては、ヘプタン酸、オクタン酸及びノナン酸がより好ましい。
【００６８】
【発明の効果】
本発明の研磨液組成物を絶縁層と金属層を有する被研磨表面の研磨に用いることにより、金属膜の研磨速度を維持し、エッチング速度を抑制し、配線金属層にディッシング等の欠陥を発生させないという効果が奏される。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a polishing liquid composition for polishing a surface to be polished having an insulating layer and a metal layer. More specifically, the present invention relates to a polishing composition, a polishing method, and a method for manufacturing a semiconductor substrate, which are applied to a method for forming a buried metal wiring on a semiconductor substrate.
[0002]
[Prior art]
In a manufacturing process of a semiconductor device, a wiring-shaped groove is formed on an insulating film surface on a semiconductor substrate, a metal film made of copper or the like is deposited on the insulating film having the groove, and the metal film is polished into a polishing apparatus and a polishing liquid. Metal chemical mechanical polishing (hereinafter referred to as metal CMP) is employed in the polishing step of the method of forming the metal wiring layer by leaving the metal layer only in the groove by polishing.
[0003]
However, this metal CMP has a problem in that a recess called dishing occurs in the metal wiring layer in the groove of the insulating film, and the cross-sectional area of the metal wiring layer decreases to cause an increase in electrical resistance. . This dishing is said to occur when the surface of the metal wiring layer is polished or etched more excessively than the surface of the insulating film with the polishing composition. In particular, copper, which is one of the main wiring metals, has a defect that dishing is likely to occur because it is excessively etched by the polishing composition.
[0004]
Accordingly, there is a demand for a polishing composition that retains the etching action for polishing the metal film on the insulating film but does not cause defects such as dishing in the metal layer during wiring formation.
[0005]
As a conventional polishing liquid, for example, JP-A-10-44047 discloses a polishing liquid containing an aqueous medium, an abrasive, an oxidizing agent, and an organic acid. However, since the etching action is too strong, the prevention of dishing is not possible. It is enough. Japanese Patent Application Laid-Open No. 11-21546 discloses a polishing solution containing a complexing agent, a film forming agent, an abrasive, and an oxidizing agent, but benzotriazole used as a film forming agent for suppressing erosion by etching is copper. Reacts with to produce a very strong film, so that the polishing rate is insufficient in metal CMP for polishing a metal layer such as copper. Japanese Patent Laid-Open No. 11-195628 discloses a polishing method using ammonium polyacrylate in combination with a polishing liquid as a substance that suppresses oxidation and etching. In metal CMP for polishing a metal layer such as copper. Surface roughness occurs on the copper surface due to ammonium polyacrylate.
[0006]
[Problems to be solved by the invention]
An object of the present invention is to maintain a polishing rate of a metal film on a surface to be polished having an insulating layer and a metal layer, suppress an etching rate, and have an excellent effect of preventing dishing of the metal wiring layer, An object is to provide a polishing method and a method for manufacturing a semiconductor substrate.
[0007]
[Means for Solving the Problems]
  The gist of the present invention is as follows.
[1] A polishing liquid composition for polishing a surface to be polished having an insulating layer and a metal layer, having 7 to 7 carbon atoms10An aliphatic carboxylic acid and / or a salt thereof,Contains etchant and waterThe polishing composition is one or more compounds selected from the following groups A to E:(Hereinafter also referred to as the first polishing liquid composition),
A: Aliphatic organic acid having 6 or less carbon atoms and having 1 to 3 carboxyl groups
B: Aromatic organic acid having 7 to 10 carbon atoms and 1 to 4 carboxyl groups
C: Organic acid having 6 or less carbon atoms and 1 to 4 phosphonic acid groups
D: Formula (I) in the molecule:
[Chemical 2]

Polyaminocarboxylic acid having two or more structures represented by
E: Inorganic acid
[2] The polishing composition according to [1], further containing an oxidizing agent (hereinafter also referred to as a second polishing composition),
[3] The polishing composition according to [1] or [2] further containing an abrasive (hereinafter also referred to as a third polishing composition),
[4] A method for polishing a semiconductor substrate, comprising polishing and planarizing a surface to be polished having an insulating layer and a metal layer, using the polishing composition according to any one of [1] to [3],
[5] [1] to [3The present invention relates to a method for producing a semiconductor substrate comprising a step of polishing and planarizing a surface to be polished having an insulating layer and a metal layer using any of the polishing liquid compositions.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
In the present invention, the use of the aliphatic carboxylic acid having 7 to 24 carbon atoms and / or a salt thereof in combination with an etching agent has one great feature, and the aliphatic carboxylic acid having 7 to 24 carbon atoms and / Or salt thereof has an action of suppressing the etching rate, and therefore, by using a polishing liquid composition containing these compounds and an etching agent, the polishing rate at a practical level is maintained, and an excessive amount of metal film is present. An excellent effect that etching can be prevented and a polished surface free from defects such as dishing can be obtained is exhibited.
[0009]
In the aliphatic carboxylic acid and / or salt thereof, from the viewpoint of maintaining the polishing rate and suppressing dishing, the aliphatic carboxylic acid and / or salt thereof has 7 to 24 carbon atoms. From the viewpoint of keeping the solubility, low foamability and polishing rate at a practical level and suppressing dishing, 7 to 20 carbon atoms are preferable, 7 to 16 carbon atoms are more preferable, 7 to 12 carbon atoms are further preferable, and 7 to 10 carbon atoms are particularly preferable. preferable.
[0010]
In addition, the hydrocarbon group of the aliphatic carboxylic acid and / or salt thereof may be either saturated or unsaturated, and may be either a linear or branched group.
[0011]
Further, the salt of the aliphatic carboxylic acid may be any of ammonium salt, organic amine salt and alkali metal salt. From the viewpoint of preventing contamination of the semiconductor, ammonium salt, monoethanolamine salt, diethanolamine salt, triethanolamine. Organic amine salts such as salts and triethylamine salts are preferred.
[0012]
Specific examples of these aliphatic carboxylic acids and salts thereof include linear saturated aliphatic carboxylic acids such as heptanoic acid, octanoic acid, nonanoic acid, decanoic acid, lauric acid, myristic acid, palmitic acid, stearic acid, and eicosanoic acid. Linear unsaturated aliphatic carboxylic acids such as heptenoic acid, octenoic acid, decenoic acid, dodecenoic acid, oleic acid, 2-methylhexanoic acid, 2-ethylhexanoic acid, 3,5-dimethylhexanoic acid, 3,5, Examples include branched-chain saturated aliphatic carboxylic acids such as 5-trimethylhexanoic acid and isodecanoic acid, and ammonium salts, organic amine salts, alkali metal salts, and the like of these aliphatic carboxylic acids. Among these, linear or branched saturated aliphatic carboxylic acid and its ammonium salt are preferable from the viewpoint of polishing rate and dishing suppression, and heptanoic acid and its ammonium salt, octane from the viewpoint of solubility in polishing liquid and low foaming property. Acid and its ammonium salt, nonanoic acid and its ammonium salt, decanoic acid and its ammonium salt are particularly preferred. These C7-24 aliphatic carboxylic acids and salts thereof may be used alone or in admixture of two or more.
[0013]
The blending amount of the aliphatic carboxylic acid and its salt in the polishing liquid composition is preferably 0.01 to 30% by weight, and preferably 0.02 to 10% by weight from the viewpoint of maintaining the polishing rate and suppressing dishing. More preferred is 0.03 to 5% by weight.
[0014]
The etching agent used in the present invention dissolves and etches metal, particularly copper, in the presence of an aqueous medium, and is a compound having an etching rate a obtained by the following etching test A of 3 Å / min or more. That is, in the etching test A, first, a copper ribbon having a length of 100 mm (manufactured by Nilaco Co., Ltd .: thickness 0.10 mm, width 6 mm) was prepared, and the surface dirt was wiped off with paper and then immersed in normal hexane. In this state, ultrasonic cleaning is performed for 1 minute, and the product is thoroughly degreased and dried. Then, the metal test piece is spirally wound so that the polishing liquid is immersed on the entire ribbon surface to obtain a metal test piece before the test, and the weight before immersion is measured with a precision balance.
[0015]
Next, 100 g of an etching solution in which the etching agent is a 2 wt% aqueous solution and the pH is adjusted to 8 ± 0.5 with ammonia water is prepared in a 150 cc beaker (Teraoka Co., Ltd. 150 cc Death Cup), and the metal The specimen is immersed for 12 hours at 25 ° C. During soaking, the magnetic stirrer is stirred to such an extent that the copper ribbon is rotated by the flow of the etching solution. After the test, the surface of the copper ribbon is sufficiently wiped off, and the weight is again measured with a precision balance to obtain the weight after the test. The amount of decrease in the copper film thickness is converted from the decrease in the weight of the copper ribbon before and after the test and is divided by the etching time to obtain the etching rate a. From the viewpoint of obtaining a practical polishing rate, an etching agent having an etching rate a obtained from the etching test A of 3 Å / min or more is preferred, an etching agent of 5 Å / min or more is more preferred, and an etching agent of 10 Å / min or more is preferred. Is more preferable. In this case, the etching rate a may be an etching rate when two or more etching agents are used in combination.
[0016]
Preferred etching agents include one or more compounds selected from the following groups A to E from the viewpoint of having an appropriate etching rate.
A: Aliphatic organic acid having 6 or less carbon atoms and having 1 to 3 carboxyl groups
B: Aromatic organic acid having 7 to 10 carbon atoms and 1 to 4 carboxyl groups
C: Organic acid having 6 or less carbon atoms and 1 to 4 phosphonic acid groups
D: Formula (I) in the molecule:
[0017]
[Chemical 1]

[0018]
Polyaminocarboxylic acid having two or more structures represented by
E: Inorganic acid
[0019]
Specifically, monocarboxylic acids such as formic acid, acetic acid, propionic acid; oxalic acid, malonic acid, succinic acid, glutaric acid as aliphatic organic acids having 6 or less carbon atoms and having 1 to 3 carboxyl groups of A; , Polycarboxylic acids such as adipic acid and tricarballylic acid; hydroxycarboxylic acids such as glycolic acid, lactic acid, 2-hydroxypropionic acid, malic acid, tartaric acid, citric acid and gluconic acid; amino acids such as glycine, alanine and aspartic acid Etc. Examples of the aromatic organic acid having 7 to 10 carbon atoms and 1 to 4 carboxyl groups of B include benzoic acid, phthalic acid, trimellitic acid, pyromellitic acid, mandelic acid, salicylic acid and the like. Examples of organic acids having 6 or less carbon atoms and having 1 to 4 carbon phosphonic acid groups include phosphonic acids such as methylphosphonic acid and phenylphosphonic acid; phosphinic acids such as methylphosphinic acid and phenylphosphinic acid; Examples thereof include phosphonic acid esters; aminophosphonic acids such as aminotri (methylenephosphonic acid) and 1-hydroxyethylidene-1-diphosphonic acid. Examples of polyaminocarboxylic acids having two or more structures represented by formula (I) in the molecule of D include ethylenediaminetetraacetic acid, nitrilotriacetic acid, diethylenediaminepentaacetic acid, triethylenetetraminehexaacetic acid, hydroxyethylethylenediaminetriacetic acid, and the like. Can be mentioned. Examples of the inorganic acid of E include hydrochloric acid, perchloric acid, sulfuric acid, nitric acid, phosphoric acid, phosphonic acid, phosphinic acid and the like. Among these, from the viewpoint of polishing rate, the polycarboxylic acid or hydroxycarboxylic acid belonging to A or B, the aminophosphonic acid belonging to C, or two or more structures represented by the formula (I) in the molecule belonging to D Polyaminocarboxylic acid, hydrochloric acid belonging to E, sulfuric acid, nitric acid and phosphoric acid are preferred. Oxalic acid, succinic acid, glycolic acid, lactic acid, citric acid, malic acid, gluconic acid, phthalic acid, aminotri (methylenephosphonic acid), 1- More preferred are hydroxyethylidene-1-diphosphonic acid, ethylenediaminetetraacetic acid, hydrochloric acid and sulfuric acid. These etching agents may be used alone or in combination of two or more.
[0020]
The etching rate a of these etching agents is, for example, glycolic acid: 60 Å / min, citric acid: 25 Å / min, phthalic acid: 50 Å / min, aminotri (methylenephosphonic acid): 10 Å / min, ethylenediaminetetraacetic acid: 30 Å. / Min, acetic acid: 70 Å / min, glycine: 40 Å / min, hydrochloric acid: 400 Å / min, sulfuric acid: 100 Å / min. Further, the etching rate a of the aliphatic carboxylic acid having 7 to 24 carbon atoms is 2 ｍｉｎ / min or less, and there is no etching power or almost no recognition as compared with the etching agent.
[0021]
The etching agent used in the present invention was further prepared into a polishing liquid composition in which an oxidant, abrasive grains, and the like coexist (however, a composition not containing an aliphatic carboxylic acid having 7 to 24 carbon atoms and / or a salt thereof). At this time, it is preferable to adjust the type, content, and the like so that the etching rate b of the polishing composition obtained from the following etching test B is 20 Å / min or more. That is, the etching test B is performed by using a polishing composition containing water, an abrasive and an etching agent and, if necessary, an oxidizing agent as an etching solution for the etching test A, except for immersion for 2 hours at room temperature (25 ° C.). Is performed in exactly the same manner as the etching test A. The etching rate obtained by the etching test B is defined as an etching rate b. From the viewpoint of obtaining a practical polishing rate, the etching rate b obtained from the etching test B is preferably 20 Å / min or more, more preferably 30 Å / min or more, and further preferably 50 Å / min or more. In this case, the etching rate b may be the etching rate of the polishing composition using two or more etching agents in combination.
[0022]
In the present invention, by using such an etchant, a complex is formed or bonded with various metals constituting the metal layer, particularly copper, and it is easily removed from the surface as a water-soluble salt and / or chelate compound. In this case, the effect of improving the polishing rate of the metal layer is exhibited.
[0023]
The blending amount of the etching agent in the polishing liquid composition can be variously selected to ensure a polishing rate at a practical level for removing the metal layer and prevent excessive etching of the metal layer, and preferably 0. 0.1 to 10% by weight, more preferably 0.2 to 8% by weight, still more preferably 0.3 to 5% by weight.
[0024]
The water used in the present invention is used as a medium. The blending amount is preferably 60 to 99.89% by weight, more preferably 70 to 99.4% by weight, and still more preferably 80 to 99% in the polishing composition from the viewpoint of efficiently polishing the object to be polished. 0.0% by weight.
[0025]
The pH of the first polishing composition of the present invention having such a composition is preferably 10 or less from the viewpoint of keeping the polishing rate at a practical level, and from the viewpoint of suppressing dishing and removing fine scratches on the surface. 9.5 is more preferable, 4-9 is further more preferable, and 7-9 is particularly preferable. In order to adjust the pH within the above range, an inorganic acid such as nitric acid or sulfuric acid, an organic acid, a basic substance such as potassium hydroxide, sodium hydroxide, ammonia, or an organic amine is added as needed. Can do.
[0026]
The second polishing liquid composition of the present invention is obtained by further blending an oxidizing agent with the first polishing liquid composition. The oxidizing agent used in the present invention oxidizes a metal. In this invention, it is thought that the effect which oxidizes a metal layer and accelerates | stimulates the mechanical polishing effect of a metal layer, or the effect of promoting the melt | dissolution of copper by an etching agent is expressed by using this oxidizing agent.
[0027]
Examples of the oxidizing agent include peroxide, permanganic acid or a salt thereof, chromic acid or a salt thereof, nitric acid or a salt thereof, peroxo acid or a salt thereof, oxygen acid or a salt thereof, metal salt, sulfuric acid, and the like.
[0028]
Specific examples thereof include hydrogen peroxide, sodium peroxide, barium peroxide and the like as peroxides; potassium permanganate as permanganic acid or a salt thereof; and metal chromate as chromic acid or a salt thereof. Salt, dichromate metal salt, etc .; as nitrate, iron nitrate (III), ammonium nitrate, etc .; as peroxo acid or its salt, peroxodisulfuric acid, ammonium peroxodisulfate, peroxodisulfate metal salt, peroxophosphoric acid, peroxosulfuric acid, Sodium peroxoborate, performic acid, peracetic acid, perbenzoic acid, perphthalic acid, etc .; oxygen acids or their salts include hypochlorous acid, hypobromous acid, hypoiodous acid, chloric acid, bromic acid, iodic acid , Perchloric acid, sodium hypochlorite, calcium hypochlorite, etc .; metal salts include iron (III) chloride, iron (III) sulfate, iron (III) citrate, Ammonium iron (III), and the like. Preferred oxidizing agents include hydrogen peroxide, iron (III) nitrate, peracetic acid, ammonium peroxodisulfate, iron (III) sulfate, and iron (III) ammonium sulfate. Particularly, hydrogen peroxide from the viewpoint of preventing contamination of semiconductors. Is preferred. These oxidizing agents may be used alone or in admixture of two or more.
[0029]
The oxidizing agent is used in a state where water is used as a medium in the second polishing composition. The blending amount of the oxidizing agent in the second polishing liquid composition is preferably 0.1 to 60% by weight, more preferably 0.2% from the viewpoint of obtaining a practical level of polishing rate by rapid oxidation of the metal layer. -50% by weight, more preferably 0.3-30% by weight, particularly preferably 0.3-10% by weight.
[0030]
The blending amount of the aliphatic carboxylic acid having 7 to 24 carbon atoms and / or a salt thereof in the second polishing liquid composition is preferably 0.01 to 30% by weight, more preferably 0.02 to 10% by weight, More preferably, it is 0.03 to 5% by weight. The blending amount of the etching agent is preferably 0.1 to 10% by weight, more preferably 0.2 to 8% by weight, and further preferably 0.3 to 5% by weight. The amount of water is preferably 39.89 to 99.79% by weight, more preferably 70 to 99.4% by weight, and still more preferably 80 to 99% by weight. As with the first polishing composition, the pH of the second polishing composition having such a composition is 10 from the viewpoint of keeping the polishing rate at a practical level, suppressing dishing, and removing fine scratches on the surface. The following is preferable, 2-9.5 is more preferable, 4-9 is further more preferable, and 7-9 is especially preferable. In order to adjust the pH within the above range, an inorganic acid such as nitric acid or sulfuric acid, an organic acid, a basic substance such as potassium hydroxide, sodium hydroxide, ammonia, or an organic amine is added as needed. Can do.
[0031]
The first and second polishing liquid compositions of the present invention are effective in a polishing method using a fixed grindstone, a polishing pad in which abrasive grains are fixed in a pad, or the like. For example, the polishing rate can be maintained and the dishing of the metal layer can be suppressed by using the first and second polishing liquid compositions of the present invention during polishing using a fixed grindstone.
[0032]
The third polishing composition of the present invention further comprises an abrasive in the first or second polishing composition and is used in a polishing method using a free abrasive.
[0033]
As the abrasive, abrasives generally used for polishing can be used, for example, metal, metal or metalloid carbide, metal or metalloid nitride, metal or metalloid oxide, metal or Examples include metalloid borides and diamond. Examples of the metal or metalloid element include those belonging to Group 3A, 4A, 5A, 3B, 4B, 5B, 6B, 7B or 8B of the periodic table. Examples thereof include silicon dioxide, aluminum oxide, cerium oxide, titanium oxide, zirconium oxide, silicon nitride, manganese dioxide, silicon carbide, zinc oxide, diamond and magnesium oxide. Among these, silicon dioxide, aluminum oxide, and cerium oxide are preferable. Specific examples thereof include colloidal silica particles, fumed silica particles, surface-modified silica particles and the like as silicon dioxide; α-alumina as aluminum oxide Particles, γ-alumina particles, δ-alumina particles, θ-alumina particles, η-alumina particles, amorphous alumina particles, and other fumed aluminas and colloidal aluminas with different production methods; cerium oxide has an oxidation number of 3 Valent or tetravalent, and those having a crystal system of hexagonal, equiaxed or face-centered cubic. Particularly preferred is silicon dioxide. These abrasives may be used alone or in admixture of two or more.
[0034]
The average particle size of the primary particles of such an abrasive is preferably 5 to 1000 nm, more preferably 10 to 500 nm, still more preferably 20 to 300 nm, particularly preferably 50 nm to 200 nm, and most preferably 50 to 100 nm. The lower limit of the average particle diameter is preferably 5 nm or more from the viewpoint of maintaining a constant polishing rate, and the upper limit thereof is preferably 1000 nm or less from the viewpoint of preventing scratches (scratches) on the surface of the object to be polished. .
[0035]
In particular, when silicon dioxide is used as the abrasive, the average particle size of the primary particles is 5 nm or more, preferably 10 nm or more, more preferably 20 nm or more from the viewpoint of improving the polishing rate.
[0036]
The average primary particle size of the abrasive is a transmission type in which 0.1 g of the abrasive is added to 100 g of 0.1% polystyrene sodium sulfonate aqueous solution, and then the abrasive is dispersed by applying ultrasonic waves. Obtained by image analysis by observation with an electron microscope.
[0037]
When the third polishing composition is used in forming the wiring of the semiconductor device, the polishing material particularly preferably used has a purity of preferably 98% by weight or more, more preferably 99% by weight or more, and particularly preferably 99.9% by weight. % Of silica particles. As such an abrasive, fumed silica produced by high-temperature hydrolysis of a volatile silicon compound such as silicon tetrachloride in an acid hydrogen bath, or a method using an alkali silicate or ethyl silicate as a starting material. Colloidal silica is mentioned.
[0038]
In addition, the purity of the abrasive is determined as follows. That is, it can be measured by dissolving 1 to 3 g of an abrasive in an acid or alkaline aqueous solution and quantifying silicon ions by an ICP (plasma emission analysis) method.
[0039]
Such an abrasive is used in a so-called slurry state in which water is used as a medium in the third polishing composition. The blending amount of the abrasive in the third polishing composition can be variously selected according to the viscosity of the polishing composition of the present invention, the required quality of the object to be polished, etc., and 0.01 to 30% by weight. Preferably, 0.1 to 20% by weight is more preferable, and 1.0 to 10% by weight is further preferable.
[0040]
The blending amount of the aliphatic carboxylic acid having 7 to 24 carbon atoms and / or a salt thereof in the third polishing liquid composition is 0.01 to 30% by weight from the viewpoint of maintaining the polishing rate and suppressing dishing. Preferably, 0.02 to 10% by weight is more preferable, and 0.03 to 5% by weight is more preferable.
[0041]
The blending amount of the etching agent in the third polishing liquid composition can be variously selected to ensure a practical level of polishing rate for removing the metal layer and prevent excessive etching of the metal layer. Is 0.1 to 10% by weight, more preferably 0.2 to 8% by weight, still more preferably 0.3 to 5% by weight.
[0042]
The blending amount of the oxidizing agent in the third polishing liquid composition is preferably 0.1 to 60% by weight, more preferably 0.2 to 0.2% from the viewpoint of obtaining a practical level of polishing rate by rapid oxidation of the metal layer. It is 50% by weight, more preferably 0.3 to 30% by weight, and particularly preferably 0.3 to 10% by weight.
[0043]
Moreover, the compounding quantity of the water in a 3rd polishing liquid composition becomes like this. Preferably it is 39.88-99.89 weight%, More preferably, it is 60-99.4 weight%, More preferably, it is 75-99 weight%. As with the first polishing composition, the pH of the third polishing composition having such a composition is 10 from the viewpoint of keeping the polishing rate at a practical level, suppressing dishing, and removing fine scratches on the surface. The following is preferable, 2-9.5 is more preferable, 4-9 is further more preferable, and 7-9 is especially preferable. In order to adjust the pH within the above range, an inorganic acid such as nitric acid or sulfuric acid, an organic acid, a basic substance such as potassium hydroxide, sodium hydroxide, ammonia, or an organic amine is added as needed. Can do.
[0044]
The first polishing composition of the present invention can be prepared, for example, by the following procedure. First, an etching agent is added to a predetermined amount of water to adjust the pH to a predetermined value. By adding a predetermined amount of an aqueous solution of an aliphatic carboxylic acid having 7 to 24 carbon atoms and / or a salt thereof previously adjusted to a predetermined pH to the aqueous solution of the etching agent having the pH adjusted, and finally adjusting the pH. A 1st polishing liquid composition can be obtained.
[0045]
The second polishing liquid composition can be prepared, for example, by the following procedure. First, an etching agent is added to a predetermined amount of water to adjust the pH to a predetermined value. A predetermined amount of an aqueous solution of an aliphatic carboxylic acid having 7 to 24 carbon atoms and / or a salt thereof, which has been adjusted to a predetermined pH in advance, is added to the aqueous solution of the etching agent whose pH has been adjusted. The second polishing composition can be obtained by adding an oxidizing agent before polishing and finally adjusting the pH.
[0046]
The third polishing liquid composition can be prepared, for example, by the following procedure. First, an etching agent is added to a predetermined amount of water to adjust the pH to a predetermined value. A predetermined amount of an abrasive is added to the aqueous solution of the etching agent whose pH has been adjusted, and the mixture is sufficiently stirred so that the abrasive is uniformly dispersed. Further, a predetermined amount of an aqueous solution of an aliphatic carboxylic acid having 7 to 24 carbon atoms and / or a salt thereof adjusted to a predetermined pH in advance is added, and if necessary, a predetermined amount of oxidizing agent is added before polishing, and finally the pH is reached. A 3rd polishing liquid composition can be obtained by adjusting.
[0047]
In addition, polishing aids other than the above, such as various surfactants and dispersion stabilizers, may be added to the first to third polishing liquid compositions.
[0048]
The polishing composition of the present invention is suitable for metal CMP, with the surface having an insulating layer and a metal layer as the object of polishing. Examples of the metal forming the metal layer include copper or a copper alloy, aluminum or an aluminum alloy, and tungsten. Among these, copper or a copper alloy is preferable particularly when used in the step of forming a buried metal wiring on a semiconductor substrate. When the polishing composition of the present invention is used to form such a copper or copper alloy metal wiring layer, the effect of maintaining the polishing rate and suppressing dishing of the embedded metal wiring layer is particularly remarkably exhibited. As the material for forming the insulating layer, any of organic and inorganic materials may be used. Silicon dioxide, fluorine-added silicon dioxide, hydrogen-containing SOG (spin-on-glass), nitride (eg, tantalum nitride, titanium nitride, etc.) ), And organic materials such as organic SOG, polyimide, fluorinated polyimide, methylpolysiloxane, aromatic polyether, hydrogensilsesquioxane, and fluorocarbon.
[0049]
The shape of these objects to be polished is preferably a shape in which a wiring-shaped groove is formed on the surface of the insulating film on the semiconductor substrate, and a metal is deposited on the insulating film including the groove. A barrier film made of tantalum, titanium, or a nitride thereof may be provided between the insulating film and the metal layer. In particular, when the metal layer is copper or a copper alloy, it is preferable to provide the barrier film because copper diffusion to the insulating layer can be prevented.
[0050]
The first and second polishing liquid compositions of the present invention are effective in a polishing method using a fixed whetstone, a polishing pad having a whetstone fixed in a pad, etc., and the third polishing liquid composition is an ordinary urethane polishing pad. It is effective in a polishing method using a free abrasive that uses a fixed abrasive, but is also effective in a polishing method using a fixed grindstone, a polishing pad having a grindstone fixed in a pad, or the like.
[0051]
The method for polishing a surface to be polished having an insulating layer and a metal layer according to the present invention includes a step of polishing and planarizing a semiconductor substrate using the polishing composition of the present invention.
[0052]
In addition, the method for producing a semiconductor substrate of the present invention uses the polishing composition of the present invention to polish a semiconductor surface having an insulating layer and a metal layer, thereby maintaining the polishing rate of the metal layer and embedding the metal wiring. Since dishing of the layer can be suppressed, it can be suitably used for manufacturing a semiconductor substrate.
[0053]
【Example】
Examples 1-12 and Comparative Examples 1-12
A predetermined amount of water is mixed with the etching agent shown in Tables 1 and 2 and hydrogen peroxide so as to have the compositions shown in Tables 1 and 2, respectively, and further mixed with 5% by weight of the abrasive shown in Tables 1 and 2, After stirring, aqueous ammonia is added so that the pH of the mixture is 7.5-8. Separately, an aqueous solution of an aliphatic carboxylic acid and a salt thereof is prepared by adding ammonia water to an aliphatic carboxylic acid having 7 to 24 carbon atoms shown in Tables 1-2 in advance to adjust the pH to 7.5-8. . The aqueous solution of the aliphatic carboxylic acid and its salt was mixed with the mixed solution so as to have the composition shown in Tables 1-2, and after stirring, the pH of the mixed solution was adjusted to the values shown in Tables 1-2. A polishing liquid composition was obtained. Each abrasive used was fumed silica (primary particle size: 50 nm) and colloidal silica (primary particle size: 100 nm). In addition, a rolled copper plate having a diameter of 50 mm and a plate thickness of 1 mm was polished by a single-side polishing machine under the following conditions. Hereinafter, the term in the brackets indicates a product name.
[0054]
<Setting conditions of single-sided machine>
Single-sided machine used: Engis single-sided machine (plate size 30cm)
Processing pressure: 29.4 × 10^ThreePa
Polishing pad: Upper layer: “IC1000” (Rodel Nitta), Lower layer: “SUBA400”
(Rodel Nitta)
Plate rotation speed: 60rpm
Work speed: 50rpm (Surface plate and work rotate in the same direction)
Polishing liquid composition supply flow rate: 100ml / min
Polishing time: 10 minutes
[0055]
Moreover, the characteristics of the polishing composition such as the relative polishing rate, the relative etching rate, dishing of the surface to be polished, and the surface state of copper were evaluated according to the following methods. These results are shown in Tables 1-2.
[0056]
(Relative polishing speed)
The relative polishing rate was obtained by dividing the polishing rate of the polishing composition by the polishing rate of the polishing composition (comparative example) with the same type and amount of the polishing composition, the abrasive, the oxidizing agent, and the etching agent. Value. The polishing rate was determined by polishing a rolled copper plate having a diameter of 50 mm and a plate thickness of 1 mm under the above polishing conditions, measuring the plate thickness change before and after polishing, and dividing it by the polishing time. The thickness of the copper plate was measured using a high-precision digital length measuring instrument “MINIAX” manufactured by Tokyo Seimitsu Co., Ltd. Examples 1-6 are Comparative Example 1, Example 7 is Comparative Example 2, Example 8 is Comparative Example 3, Example 9 is Comparative Example 4, Example 10 is Comparative Example 5, Example 11 Is based on Comparative Example 11, Example 12 is based on Comparative Example 12, Comparative Example 9 is based on Comparative Example 1, and Comparative Example 10 is based on Comparative Example 2. In Comparative Examples 6 to 8, the relative polishing rate was calculated using Comparative Example 1 as a reference, unlike the above definition.
[0057]
(Relative etching rate)
The relative etching rate is the same as the etching rate of the polishing composition containing the aliphatic carboxylic acid and / or salt thereof, but does not contain the aliphatic carboxylic acid and / or salt thereof, but the type and amount of the abrasive, oxidizing agent and etching agent. Is a value obtained by dividing by the etching rate b of the polishing composition having the same value. Examples 1-6 are Comparative Example 1, Example 7 is Comparative Example 2, Example 8 is Comparative Example 3, Example 9 is Comparative Example 4, Example 10 is Comparative Example 5, Example 11 Is based on Comparative Example 11, Example 12 is based on Comparative Example 12, Comparative Example 9 is based on Comparative Example 1, and Comparative Example 10 is based on Comparative Example 2. In Comparative Examples 6 to 8, the relative etching rate was calculated using Comparative Example 1 as a reference, unlike the above definition. Moreover, the etching rate of the polishing composition of Examples 1-12 and Comparative Examples 7-8 is the value measured on the same conditions as the said etching test B except using these polishing composition.
[0058]
(Dishing)
For dishing evaluation, a 20 mm square wafer chip was cut out from a wafer with a copper damascene wiring pattern (SKW6-2, size: 200 mm), and 5 wafer chips were fixed to a ceramic bonding plate While confirming the state under the above conditions, the copper film around the copper wiring part with a wiring width of 150 μm is removed and polishing is performed until the barrier film appears, and further polishing is performed for 20% of the polishing time required up to this point. A dishing evaluation sample was used. The dishing was evaluated by measuring a cross-sectional profile of a copper wiring portion having a wiring width of 150 μm on the wafer chip with a surface roughness measuring machine (“SV-600” manufactured by Mitutoyo Corporation). In addition, when there is no dent of 0.15 μm or more in the measured cross-sectional profile of the copper wiring, no dishing is given, and when there is a dent of 0.15 μm or more, dishing is given. “Yes”.
[0059]
(Copper surface condition)
The surface state of the copper film in the copper wiring portion having a wiring width of 150 μm on the wafer chip surface used for the dishing evaluation was observed with an optical microscope to confirm the presence or absence of roughness.
[0060]
In addition, the etching rate b of the polishing liquid composition of Comparative Examples 1-6 is as follows. Comparative Example 1 (50 Å / min), Comparative Example 2 (100 Å / min), Comparative Example 3 (200 Å / min), Comparative Example 4 (600 Å / min), Comparative Example 5 (50 Å / min), Comparative Example 6 (100 Å) / Min).
[0061]
[Table 1]

[0062]
[Table 2]

[0063]
From the results of Tables 1 and 2, Comparative Examples 1 to 5, 11, and 12 in which none of the polishing liquid compositions of Examples 1 to 12 in which an aliphatic carboxylic acid having 7 to 24 carbon atoms was mixed with the polishing liquid composition were used. It can be seen that the etching rate is suppressed and dishing does not occur without substantially reducing the polishing rate as compared with the polishing liquid composition.
[0064]
In addition, the polishing composition of Comparative Example 6 which uses two types of aliphatic carboxylic acids having 6 or less carbon atoms without using 7 to 24 carbon carboxylic acids has a high etching rate and dishing. It can be seen that this occurs.
[0065]
Further, the polishing composition of Comparative Example 7 using two types of aliphatic carboxylic acids having 7 to 24 carbon atoms and the polishing composition of Comparative Example 8 that does not contain an organic acid that forms a water-soluble salt with copper. The polishing liquid composition of Comparative Example 9 containing benzotriazole that suppresses etching and etching has a very low polishing rate, and the polishing liquid composition of Comparative Example 10 containing ammonium polyacrylate is rough on the copper surface. It can be seen that has occurred.
[0066]
Therefore, it can be seen that a higher polishing rate can be realized and dishing can be prevented by using an aliphatic carboxylic acid having 7 to 24 carbon atoms and an etching agent in combination.
[0067]
In particular, heptanoic acid, octanoic acid and nonanoic acid are more preferable as the aliphatic carboxylic acid having 7 to 24 carbon atoms from the viewpoint of foaming during polishing.
[0068]
【The invention's effect】
By using the polishing composition of the present invention for polishing a surface to be polished having an insulating layer and a metal layer, the polishing rate of the metal film is maintained, the etching rate is suppressed, and defects such as dishing are generated in the wiring metal layer. The effect of not letting it be played.

Claims (5)

A polishing liquid composition for polishing a surface to be polished having an insulating layer and a metal layer, comprising an aliphatic carboxylic acid having 7 to 10 carbon atoms and / or a salt thereof, an etching agent and water, and the etching agent Is a polishing liquid composition, which is one or more compounds selected from the following groups A to E.
A: Aliphatic organic acid having 6 or less carbon atoms and having 1 to 3 carboxyl groups
B: Aromatic organic acid having 7 to 10 carbon atoms and 1 to 4 carboxyl groups
C: Organic acid having 6 or less carbon atoms and 1 to 4 phosphonic acid groups
D: Formula (I) in the molecule:

Polyaminocarboxylic acid having two or more structures represented by
E: Inorganic acid The polishing composition according to claim 1, further comprising an oxidizing agent. The polishing composition according to claim 1 or 2, further comprising an abrasive. A method for polishing a semiconductor substrate, comprising polishing and planarizing a surface to be polished having an insulating layer and a metal layer using the polishing composition according to claim 1. The manufacturing method of a semiconductor substrate which has the process of grind | polishing and planarizing the to-be-polished surface which has an insulating layer and a metal layer using the polishing liquid composition in any one of Claims 1-3.