本發明者等人為了解決上述問題而進行了各種研究。其結果為獲得了以下見解。 為了控制研磨後之晶圓之形狀，有效的是使研磨用組合物中適量含有兩種以上之水溶性高分子。兩種以上之水溶性高分子視與晶圓之親和性之不同，而分別作用於晶圓之相對內側之區域與相對外側之區域。進而，藉由適當控制兩種以上之水溶性高分子各者與研磨粒之濃度比，可不使研磨速度降低而以更高水準控制晶圓之形狀。 本發明係基於該等見解而完成。以下，對本發明之一實施形態之研磨用組合物進行詳細敍述。 本發明之一實施形態之研磨用組合物包含研磨粒、鹼性化合物、及兩種以上之水溶性高分子。本實施形態之研磨用組合物可較佳地用於矽晶圓之二次研磨。 研磨粒可使用該領域中常用者。研磨粒例如為膠體二氧化矽、發煙二氧化矽、膠體氧化鋁、發煙氧化鋁、氧化鈰、碳化矽、氮化矽等。該等中，可較佳地使用膠體二氧化矽。 研磨粒之含量並無特別限定，例如為研磨用組合物總體之0.1～15重量%。關於研磨粒之含量，就使研磨速度變大之觀點而言以多為佳，就減少研磨損傷或異物殘留之觀點而言以少為佳。研磨粒之含量之下限較佳為0.5重量%，進而較佳為1重量%。研磨粒之含量之上限較佳為12重量%，進而較佳為10重量%。 鹼性化合物對晶圓之表面進行蝕刻而進行化學研磨。鹼性化合物例如為胺化合物、無機鹼性化合物等。 胺化合物例如為一級胺、二級胺、三級胺、四級銨及其鹽、雜環式胺等。具體而言可列舉：氨、氫氧化四甲基銨(TMAH)、氫氧化四乙基銨(TEAH)、氫氧化四丁基銨(TBAH)、甲胺、二甲胺、三甲胺、乙胺、二乙胺、三乙胺、己胺、環己胺、乙二胺、六亞甲基二胺、二伸乙基三胺(DETA)、三伸乙基四胺、四伸乙基五胺、五伸乙基六胺、單乙醇胺、二乙醇胺、三乙醇胺、N-(β-胺基乙基)乙醇胺、無水哌𠯤、哌𠯤六水合物、1-(2-胺基乙基)哌𠯤、N-甲基哌𠯤、哌𠯤鹽酸鹽、碳酸胍等。 無機鹼性化合物例如可列舉：鹼金屬之氫氧化物、鹼金屬之碳酸鹽、鹼金屬之碳酸氫鹽、鹼土金屬之氫氧化物、鹼土金屬之碳酸鹽、鹼土金屬之碳酸氫鹽等。無機鹼性化合物具體而言為氫氧化鉀(KOH)、氫氧化鈉、碳酸氫鉀、碳酸鉀(K2
CO3
)、碳酸氫鈉、碳酸鈉等。 鹼性化合物可較佳地使用上述列舉之物質群中之鹼金屬之氫氧化物、鹼金屬之碳酸鹽、鹼土金屬之氫氧化物、鹼土金屬之碳酸鹽、四級銨、或四級銨之鹽。如上所述，本實施形態之研磨用組合物可較佳地用於矽晶圓之二次研磨。對於精加工研磨(最終研磨)用之研磨用組合物而言，純度之要求非常高，因此鹼金屬等之含量受到限制，相對於此，二次研磨用之研磨用組合物與精加工研磨用之研磨用組合物相比而要求研磨速率。因此，二次研磨用之研磨用組合物較佳為使用化學研磨作用較強之鹼性化合物。 上述鹼性化合物可單獨使用一種，亦可混合使用兩種以上。鹼性化合物之合計含量並無特別限定，例如為研磨用組合物總體之0.1～5重量%。鹼性化合物之含量之下限較佳為0.5重量%。鹼性化合物之含量之上限較佳為3重量%。 本實施形態之研磨用組合物包含兩種以上之水溶性高分子。水溶性高分子吸附於晶圓之表面，將晶圓之表面改質。藉此，可提昇研磨之均勻性，降低表面粗糙度。 水溶性高分子例如可列舉：羥乙基纖維素(HEC)、羥丙基纖維素、羧甲基纖維素、乙酸纖維素、甲基纖維素等纖維素類；聚乙烯醇(PVA)、聚乙烯吡咯啶酮(PVP)等乙烯聚合物；配醣體(糖苷)、聚乙二醇、聚丙二醇、聚甘油、泊洛沙胺、泊洛沙姆、聚氧伸烷基烷基醚、聚氧伸烷基脂肪酸酯、聚氧伸烷基烷基胺、甲基葡萄糖苷之環氧烷衍生物(下文敍述)、多元醇環氧烷加成物、多元醇脂肪酸酯等。 研磨時，該等兩種以上之水溶性高分子視與晶圓之親和性之不同而分別作用於晶圓之相對內側之區域與相對外側之區域。藉此，可以更高水準控制晶圓之形狀。 於本實施形態之研磨用組合物中，兩種以上之水溶性高分子各者與研磨粒之重量%濃度比為研磨粒：水溶性高分子＝1：0.0001～1：0.0010。 若水溶性高分子變得較研磨粒：水溶性高分子＝1：0.0001少，則無法充分獲得該水溶性高分子之作用，無法充分獲得藉由含有兩種以上之水溶性高分子所得之效果。其結果為，無法獲得目標晶圓形狀。另一方面，若水溶性高分子變得較研磨粒：水溶性高分子＝1：0.0010多，則研磨速度降低。又，無法充分獲得藉由含有兩種以上之水溶性高分子所得之效果，仍然無法獲得目標晶圓形狀。兩種以上之水溶性高分子各者與研磨粒之重量%濃度比之上限較佳為以水溶性高分子/研磨粒計為0.0009，進而較佳為以水溶性高分子/研磨粒計為0.0007。 水溶性高分子中之一種較佳為包含下述通式(1)所示之具有2個氮之伸烷基二胺結構，且於該伸烷基二胺結構之2個氮上鍵結有至少1個嵌段型聚醚的二胺化合物，並且該嵌段型聚醚係氧伸乙基與氧伸丙基鍵結而成(以下稱為「鍵結有嵌段型聚醚之二胺化合物」)。 [化1](式中，n表示1以上之整數) 嵌段型聚醚可使用選自下述通式(2)～(5)所示之醚基中之至少一種。 -[(EO)a
-(PO)b
]x
-H ・・・(2) -[(PO)b
-(EO)a
]x
-H ・・・(3) -(EO)a
-[(PO)b
-(EO)a
]x
-H ・・・(4) -(PO)b
-[(EO)a
-(PO)b
]x
-H ・・・(5) 式中，EO表示氧伸乙基，PO表示氧伸丙基，a、b、x為1以上之整數。較佳為氧伸乙基之數量a為1～500，氧伸丙基之數量b為1～200。較佳為氧伸乙基與氧伸丙基之質量比為EO：PO＝10：90～80：20。 作為鍵結有嵌段型聚醚之二胺化合物之具體例，可列舉N,N,N',N'-四-聚氧伸乙基-聚氧伸丙基-乙二胺(泊洛沙胺)。 水溶性高分子中之一種較佳為HEC。 作為研磨用組合物所含有之兩種以上之水溶性高分子，自不對晶圓表面賦予濡濕性之水溶性高分子中選擇一種以上，且自對晶圓表面賦予濡濕性之水溶性高分子中選擇一種以上。 不對晶圓表面賦予濡濕性之水溶性高分子係指一分子中之羥基或內醯胺結構之數量未達10(於存在羥基及內醯胺結構兩者之情形時，其合計未達10)的水溶性高分子。作為不對晶圓表面賦予濡濕性之水溶性高分子，例如可除了上述泊洛沙胺以外，可列舉：泊洛沙姆、聚氧伸烷基烷基醚、聚氧伸烷基脂肪酸酯、聚氧伸烷基烷基胺、及下述通式(6)所示之甲基葡萄糖苷之環氧烷衍生物、多元醇環氧烷加成物、多元醇脂肪酸酯、聚乙二醇、聚丙二醇等。 [化2](式中，AO表示環氧烷，又，a～d表示整數) 具體而言，聚氧伸烷基烷基醚為聚氧伸乙基月桂醚、聚氧伸乙基鯨蠟醚、聚氧伸乙基硬脂醚等。具體而言，聚氧伸烷基脂肪酸酯為聚氧伸乙基單月桂酸酯、聚氧伸乙基單硬脂酸酯等。具體而言，聚氧伸烷基烷基胺為聚氧伸乙基月桂基胺、聚氧伸乙基油基胺等。甲基葡萄糖苷之環氧烷衍生物例如為聚氧伸乙基甲基葡萄糖苷、聚氧伸丙基甲基葡萄糖苷等。具體而言，多元醇環氧烷加成物可列舉甘油、季戊四醇、乙二醇等之環氧烷加成物等。 對晶圓表面賦予濡濕性之水溶性高分子係指一分子中之羥基或內醯胺結構之數量為10以上(於存在羥基及內醯胺結構兩者之情形時，其合計為10以上)的水溶性高分子。對晶圓表面賦予濡濕性之水溶性高分子例如可列舉：羥乙基纖維素(HEC)、羥丙基纖維素、羧甲基纖維素、乙酸纖維素、甲基纖維素等纖維素類；聚乙烯醇(PVA)、聚乙烯吡咯啶酮(PVP)等；乙烯聚合物、配醣體(糖苷)、聚甘油等。 研磨用組合物所含有之兩種以上之水溶性高分子較佳為自由泊洛沙胺、泊洛沙姆、聚氧伸乙基甲基葡萄糖苷、聚氧伸丙基、甲基葡萄糖苷所組成之群中選擇一種，且自由HEC、PVA、PVP、聚甘油所組成之群中選擇另一種。研磨用組合物所含有之兩種以上之水溶性高分子進而較佳為將一種設為泊洛沙胺，另一種設為HEC。 本實施形態之研磨用組合物亦可除上述外還包含螯合劑。螯合劑例如為胺基羧酸系螯合劑，有機磺酸螯合劑等。 作為胺基羧酸系螯合劑，具體而言可列舉：乙二胺四乙酸、乙二胺四乙酸鈉、氮基三乙酸、氮基三乙酸鈉、氮基三乙酸銨、羥乙基乙二胺三乙酸、羥乙基乙二胺三乙酸鈉、二伸乙基三胺五乙酸(DTPA)、二伸乙基三胺五乙酸鈉、三伸乙基四胺六乙酸、三伸乙基四胺六乙酸鈉等。 作為有機膦酸系螯合劑，具體而言可列舉：2-胺基乙基膦酸、1-羥基亞乙基-1,1-二膦酸、胺基三(亞甲基膦酸)、乙二胺四(亞甲基膦酸)、二伸乙基三胺五(亞甲基膦酸)、乙烷-1,1,-二膦酸、乙烷-1,1,2-三膦酸、乙烷-1-羥基-1,1-二膦酸、乙烷-1-羥基-1,1,2-三膦酸、乙烷-1,2-二羧基-1,2-二膦酸、甲烷羥基膦酸、2-膦酸基丁烷-1,2-二羧酸、1-膦酸基丁烷-2,3,4-三羧酸、α-甲基膦酸基琥珀酸等。 本實施形態之研磨用組合物亦可進而包含pH值調整劑。本實施形態之研磨用組合物之pH值較佳為8.0～12.0。 本實施形態之研磨用組合物除上述以外，還可任意調配研磨用組合物之領域中通常知悉之添加劑。 本實施形態之研磨用組合物係藉由將研磨粒、鹼性化合物、兩種以上之水溶性高分子及其他調配材料適當混合並加水而製作。或者，本實施形態之研磨用組合物係藉由將研磨粒、鹼性化合物、兩種以上之水溶性高分子及其他調配材料依序混合至水中而製作。作為混合該等成分之方法，可使用均質機、超音波等研磨用組合物之技術領域中常用之方法。 以上說明之研磨用組合物係以成為適當濃度之方式以水稀釋後，用於矽晶圓之研磨。 [實施例] 以下，藉由實施例對本發明更具體地進行說明。本發明不限定於該等實施例。 [研磨例1] 製作表1所示之實施例1～4、及表2所示之比較例1～4之研磨用組合物。 [表1]
[表2]
實施例1之研磨用組合物含有粒徑70 nm之膠體二氧化矽作為研磨粒，含有DTPA作為螯合劑，含有KOH及K2
CO3
作為鹼性化合物，且含有泊洛沙胺及HEC作為水溶性高分子。研磨用組合物之剩餘部分為水。研磨粒、DTPA、KOH、K2
CO3
、泊洛沙胺、及HEC之含量係分別設為3重量%、0.01重量%、0.3重量%、1重量%、0.0004重量%、及0.0004重量%。研磨粒與泊洛沙胺之重量%濃度比、及研磨粒與HEC之重量%濃度比均為1：0.0001。 實施例2～4之研磨用組合物係以實施例1之研磨用組合物為基準，改變泊洛沙胺及HEC之含量，且將研磨粒與各水溶性高分子之重量%濃度比設為1：0.0003、1：0.0007、1：0.001而成者。 比較例1之研磨用組合物係以實施例1之研磨用組合物為基準，未添加水溶性高分子者。 比較例2之研磨用組合物係以實施例1之研磨用組合物為基準，改變泊洛沙胺及HEC之含量，且將研磨粒與各水溶性高分子之重量%濃度比設為1：0.0013而成者。比較例3之研磨用組合物係以實施例4之研磨用組合物為基準，未添加HEC者。比較例4之研磨用組合物係以實施例4之研磨用組合物為基準，未添加泊洛沙胺者。 使用該等實施例及比較例之研磨用組合物，進行直徑300 mm之P型矽晶圓(100)面之研磨。研磨裝置係使用岡本工作機械製作所股份有限公司製作之SPP800S。研磨墊係使用麂皮之研磨墊。將研磨用組合物稀釋至10倍，以0.6 L/分鐘之供給速度進行供給。壓盤之轉速設為43 rpm，研磨頭之轉速設為40 rpm，研磨負荷設為0.012 MPa，進行4分鐘之研磨。 研磨結束後，使用非接觸表面粗糙度測定機(WycoNT9300，Veeco公司製造)，測定矽晶圓之表面粗糙度Ra。 晶圓形狀之評價係使用以下將說明之「差量GBIR」而進行。 圖1係用以對差量GBIR進行說明之圖。首先，測定研磨前之矽晶圓之厚度(距背面基準平面之距離)之分佈P1。同樣地，測定研磨後之矽晶圓之厚度之分佈P2。取研磨前之分佈P1與研磨後之分佈P2之差量，求出「藉由研磨而去除之厚度(磨削量)」之分佈ΔP。將除特定邊緣區域以外之區域中之磨削量之分佈ΔP的最大值ΔPmax
與最小值ΔPmin
之差定義為「差量GBIR」。 使用差量GBIR對晶圓形狀進行評價，由此與使用通常之GBIR之情形相比，可緩和由研磨前之矽晶圓之不均及意外因素所造成之影響，更準確地進行研磨步驟本身之評價。 研磨前後之矽晶圓之厚度之分佈係使用晶圓用平坦度檢查裝置(Nonometro 300TT-A，黑田精工股份有限公司製造)測定。又，將磨削量之平均厚度除以研磨時間，作為研磨速率。 將研磨速率、表面粗糙度Ra、差量GBIR示於上述表1及表2中。表1及表2之研磨速率、表面粗糙度Ra、差量GBIR之數量值為將比較例1(不含水溶性高分子之研磨用組合物)之值設為100時之相對值。於本評價中，將研磨速率成為90以上，表面粗糙度Ra成為110以下，差量GBIR成為70以下視為目標。 如表1所示，於實施例1～5中，研磨速率係維持於與比較例1同等，表面粗糙度Ra及差量GBIR大幅度地改善。若將實施例1～4進行比較，則獲得大致相同之品質，但水溶性高分子相對於研磨粒之濃度比較小之實施例1及2之情況下可見差量GBIR變小之傾向。 如表2所示，比較例2雖然與比較例1相比表面粗糙度Ra改善，但研磨速率下降。又，差量GBIR未改善。可認為其原因在於水溶性高分子相對於研磨粒之濃度比過高。 比較例3、4雖然與比較例1相比而研磨速率變大，但差量GBIR之改善不充分。可認為其原因在於該等研磨用組合物僅含有一種水溶性高分子。 [研磨例2] 繼而，製作表3所示之比較例5～10之研磨用組合物。 [表3]
比較例5之研磨用組合物係與比較例1同樣地以實施例1之研磨用組合物為基準，未添加水溶性高分子者。 比較例6～8之研磨用組合物係以比較例4之研磨用組合物為基準，改變HEC之含量，且將研磨粒與HEC之重量%濃度比設為1：0.0013、1：0027、1：0.005而成者。比較例9之研磨用組合物係以比較例3之研磨用組合物為基準，改變泊洛沙胺之含量，且將研磨粒與泊洛沙胺之重量%濃度比設為1：0.0013而成者。比較例10之研磨用組合物係將研磨粒與泊洛沙胺之重量%濃度比、及研磨粒與HEC之重量%濃度比均設為1：0.0013而成者。 使用該等研磨用組合物，於與研磨例1類似之條件下進行研磨。然後，與研磨例1同樣地求出研磨速率、表面粗糙度Ra、差量GBIR。將結果示於上述表3中。表3之研磨速率、表面粗糙度Ra、差量GBIR之數量值係將比較例5(不含水溶性高分子之研磨用組合物)之值設為100時之相對值。 比較例6與比較例5相比，差量GBIR之改善不充分。比較例7及8雖然差量GBIR改善，但研磨速率大幅度地降低。比較例9與比較例5相比差量GBIR惡化。如此，於水溶性高分子為一種之情形時，即便調整含量，亦無法獲得平衡良好地滿足研磨速率、表面粗糙度Ra、差量GBIR此3個指標之條件。 圖2～圖5分別為藉由比較例5(無水溶性高分子)、比較例9(僅泊洛沙胺)、比較例6(僅HEC)、及比較例10(併用泊洛沙胺與HEC)之研磨用組合物進行了研磨的矽晶圓之磨削量之分佈。 根據圖2與圖3之比較可知，泊洛沙胺不使晶圓中心之磨削量變化，且使晶圓最外周之磨削量變小。 根據圖2與圖4之比較可知，HEC使晶圓中心之磨削量變小，且使晶圓最外周之磨削量變大。 如圖5所示，藉由併用泊洛沙胺與HEC，晶圓中心至外周附近之磨削量之變化變少，可於晶圓之中心與距中心100 mm之位置之間使磨削量基本一定。 [研磨例3] 繼而，製作表4所示之實施例5～8、表5所示之實施例10、11、比較例11～13之研磨用組合物。 [表4]
[表5]
實施例5～7之研磨用組合物係以實施例2之研磨用組合物為基準，將HEC替換為其他水溶性高分子而成者。具體而言，實施例5～7之研磨用組合物係將HEC分別替換為PVA、PVP、及聚甘油而成者。實施例8～10之研磨用組合物係以實施例2之研磨用組合物為基準，將泊洛沙胺替換為其他水溶性高分子而成者。具體而言，實施例8～10之研磨用組合物係將泊洛沙胺分別替換為泊洛沙姆、聚氧伸乙基甲基葡萄糖苷、及聚氧伸丙基甲基葡萄糖苷而成者。 比較例11之研磨用組合物係與比較例1同樣地以實施例1之研磨用組合物為基準，未添加水溶性高分子者。 比較例12之研磨用組合物係以比較例4之研磨用組合物為基準，改變HEC之含量，且將研磨粒與HEC之重量%濃度比設為1：0.002而成者。比較例13之研磨用組合物係以比較例3之研磨用組合物為基準，改變泊洛沙胺之含量，且將研磨粒與泊洛沙胺之重量%濃度比設為1：0.002而成者。 使用該等研磨用組合物，於與研磨例1類似之條件下進行研磨。然後，與研磨例1同樣地求出研磨速率、表面粗糙度Ra、差量GBIR。將結果示於上述表4及表5中。表4及表5之研磨速率、表面粗糙度Ra、差量GBIR之數量值為將比較例11(不含水溶性高分子之研磨用組合物)之值設為100時之相對值。 於實施例5～10中，研磨速率及表面粗糙度Ra與比較例11為同等或同等以上，差量GBIR大幅度地改善。尤其，實施例5(水溶性高分子為泊洛沙胺與PVA)、實施例7(水溶性高分子為泊洛沙胺與聚甘油)中，研磨速率亦顯著提昇。 比較例12、13係差量GBIR之改善不充分。可認為其原因在於該等研磨用組合物僅含有一種水溶性高分子。 根據以上之結果確認到，藉由使研磨用組合物中適量含有兩種以上之水溶性高分子，可以高水準控制研磨後之晶圓之形狀。 以上，對本發明之實施形態進行了說明。上述實施形態僅為用以實施本發明之例示。因此，本發明並不限定於上述實施形態，可於不脫離其主旨之範圍內將上述實施形態適當變化後實施。The inventors of the present invention have conducted various studies in order to solve the above-mentioned problems. As a result, the following findings were obtained. In order to control the shape of the polished wafer, it is effective to include two or more water-soluble polymers in an appropriate amount in the polishing composition. The two or more water-soluble polymers act on the relatively inner region and the relatively outer region of the wafer, respectively, depending on their affinity with the wafer. Furthermore, by appropriately controlling the concentration ratio of each of the two or more water-soluble polymers and the abrasive grains, the shape of the wafer can be controlled at a higher level without reducing the polishing rate. The present invention has been completed based on these findings. Hereinafter, the polishing composition according to one embodiment of the present invention will be described in detail. The polishing composition according to one embodiment of the present invention includes abrasive particles, a basic compound, and two or more water-soluble polymers. The polishing composition of this embodiment can be preferably used for secondary polishing of silicon wafers. As abrasive grains, those commonly used in this field can be used. The abrasive particles are, for example, colloidal silica, fumed silica, colloidal alumina, fumed alumina, cerium oxide, silicon carbide, silicon nitride, and the like. Among these, colloidal silica can be preferably used. The content of the abrasive grains is not particularly limited, but is, for example, 0.1 to 15% by weight of the entire polishing composition. The content of the abrasive grains is preferably large from the viewpoint of increasing the polishing rate, and is preferably small from the viewpoint of reducing polishing damage and foreign matter residues. The lower limit of the content of the abrasive grains is preferably 0.5% by weight, more preferably 1% by weight. The upper limit of the content of the abrasive particles is preferably 12% by weight, more preferably 10% by weight. The alkaline compound chemically polishes the surface of the wafer by etching. The basic compound is, for example, an amine compound, an inorganic basic compound, and the like. The amine compound is, for example, primary amine, secondary amine, tertiary amine, quaternary ammonium and its salt, heterocyclic amine, and the like. Specifically, ammonia, tetramethylammonium hydroxide (TMAH), tetraethylammonium hydroxide (TEAH), tetrabutylammonium hydroxide (TBAH), methylamine, dimethylamine, trimethylamine, ethylamine , Diethylamine, Triethylamine, Hexylamine, Cyclohexylamine, Ethylenediamine, Hexamethylenediamine, Diethylenetriamine (DETA), Triethylenetetramine, Tetraethylenepentamine , Pentaethylene hexamine, monoethanolamine, diethanolamine, triethanolamine, N-(β-aminoethyl)ethanolamine, anhydrous piperamine, piperidine hexahydrate, 1-(2-aminoethyl)piperidine 𠯤, N-methylpiperidine 𠯤, piper 𠯤 hydrochloride, guanidine carbonate, etc. Examples of inorganic basic compounds include alkali metal hydroxides, alkali metal carbonates, alkali metal hydrogencarbonates, alkaline earth metal hydroxides, alkaline earth metal carbonates, and alkaline earth metal hydrogencarbonates. Specifically, the inorganic basic compound is potassium hydroxide (KOH), sodium hydroxide, potassium hydrogen carbonate, potassium carbonate (K 2 CO 3 ), sodium hydrogen carbonate, sodium carbonate, and the like. The basic compound can be preferably used alkali metal hydroxides, alkali metal carbonates, alkaline earth metal hydroxides, alkaline earth metal carbonates, quaternary ammonium, or quaternary ammonium in the above-listed substance group. Salt. As described above, the polishing composition of this embodiment can be preferably used for secondary polishing of silicon wafers. For the polishing composition for finishing polishing (final polishing), the requirement of purity is very high, so the content of alkali metals and the like is limited. In contrast, the polishing composition for secondary polishing and the polishing composition for finishing polishing The polishing rate is required in comparison with the polishing composition. Therefore, as the polishing composition for secondary polishing, it is preferable to use a basic compound having a strong chemical polishing effect. The above-mentioned basic compounds may be used alone or in combination of two or more. The total content of the basic compounds is not particularly limited, but is, for example, 0.1 to 5% by weight of the entire polishing composition. The lower limit of the content of the basic compound is preferably 0.5% by weight. The upper limit of the content of the basic compound is preferably 3% by weight. The polishing composition of the present embodiment contains two or more water-soluble polymers. The water-soluble polymer is adsorbed on the surface of the wafer to modify the surface of the wafer. Thereby, the uniformity of grinding can be improved and the surface roughness can be reduced. Examples of water-soluble polymers include celluloses such as hydroxyethyl cellulose (HEC), hydroxypropyl cellulose, carboxymethyl cellulose, cellulose acetate, and methyl cellulose; polyvinyl alcohol (PVA), polymer Vinyl pyrrolidone (PVP) and other vinyl polymers; glycosides (glycosides), polyethylene glycol, polypropylene glycol, polyglycerol, poloxamine, poloxamer, polyoxyalkylene alkyl ether, poly Oxyalkylene fatty acid esters, polyoxyalkylene alkylamines, alkylene oxide derivatives of methyl glucoside (described below), polyol alkylene oxide adducts, polyol fatty acid esters, and the like. During polishing, the two or more water-soluble polymers act on the relatively inner region and the relatively outer region of the wafer, respectively, depending on their affinity with the wafer. Thereby, the shape of the wafer can be controlled at a higher level. In the polishing composition of the present embodiment, the weight % concentration ratio of each of the two or more water-soluble polymers and the abrasive grains is abrasive grain:water-soluble polymer=1:0.0001 to 1:0.0010. When the water-soluble polymer becomes smaller than that of abrasive particles: water-soluble polymer=1:0.0001, the effect of the water-soluble polymer cannot be sufficiently obtained, and the effect obtained by containing two or more water-soluble polymers cannot be sufficiently obtained. As a result, the target wafer shape cannot be obtained. On the other hand, when the water-soluble polymer becomes larger than the abrasive grains:water-soluble polymer=1:0.0010, the polishing rate decreases. In addition, the effect obtained by containing two or more water-soluble polymers cannot be sufficiently obtained, and the target wafer shape cannot be obtained. The upper limit of the weight % concentration ratio of each of the two or more water-soluble polymers to the abrasive particles is preferably 0.0009 in terms of water-soluble polymers/abrasive particles, and more preferably 0.0007 in terms of water-soluble polymers/abrasive particles . One of the water-soluble polymers preferably includes an alkylene diamine structure having two nitrogens represented by the following general formula (1), and is bonded to the two nitrogens of the alkylene diamine structure. At least one diamine compound of a block-type polyether, and the block-type polyether-based oxyethylene group and oxypropylene group are bonded (hereinafter referred to as "block-type polyether-bound diamine") compound"). [hua 1] (In the formula, n represents an integer of 1 or more.) As the block-type polyether, at least one selected from ether groups represented by the following general formulae (2) to (5) can be used. -[(EO) a -(PO) b ] x -H ・・・(2) -[(PO) b -(EO) a ] x -H ・・・(3) -(EO) a -[( PO) b -(EO) a ] x -H ・・・(4) -(PO) b -[(EO) a -(PO) b ] x -H ・・・(5) where EO represents oxygen Ethylene, PO represents oxypropylene, and a, b, and x are integers of 1 or more. Preferably, the number a of oxyethylene groups is 1-500, and the number b of oxypropylene groups is 1-200. Preferably, the mass ratio of oxyethylene and oxypropylene is EO:PO=10:90～80:20. Specific examples of the block-type polyether-bonded diamine compound include N,N,N',N'-tetra-polyoxyethylene-polyoxypropylene-ethylenediamine (poloxa amine). One of the water-soluble polymers is preferably HEC. As two or more water-soluble polymers contained in the polishing composition, one or more water-soluble polymers that do not impart wettability to the wafer surface are selected from among water-soluble polymers that impart wettability to the wafer surface. Choose more than one. A water-soluble polymer that does not impart wettability to the wafer surface means that the number of hydroxyl groups or lactamide structures in one molecule is less than 10 (in the case of both the hydroxyl group and the lactamide structure, the total is less than 10) water-soluble polymers. Examples of water-soluble polymers that do not impart wettability to the wafer surface include, in addition to the above-mentioned poloxamine, poloxamers, polyoxyalkylene alkyl ethers, polyoxyalkylene fatty acid esters, Polyoxyalkylene alkylamines, and alkylene oxide derivatives of methyl glucosides represented by the following general formula (6), polyol alkylene oxide adducts, polyol fatty acid esters, polyethylene glycols , polypropylene glycol, etc. [hua 2] (In the formula, AO represents an alkylene oxide, and a to d represent an integer.) Specifically, the polyoxyalkylene alkyl ether is polyoxyethylene lauryl ether, polyoxyethylene cetyl ether, polyoxyethylene Ethyl stearyl ether, etc. Specifically, the polyoxyalkylene fatty acid ester is polyoxyethylene monolaurate, polyoxyethylene monostearate, and the like. Specifically, the polyoxyalkylene alkylamine is polyoxyethylene laurylamine, polyoxyethylene oleylamine, and the like. The alkylene oxide derivatives of methyl glucoside are, for example, polyoxyethylene methyl glucoside, polyoxypropylene methyl glucoside, and the like. Specific examples of the polyol alkylene oxide adduct include alkylene oxide adducts such as glycerin, pentaerythritol, and ethylene glycol. The water-soluble polymer that imparts wettability to the wafer surface means that the number of hydroxyl groups or lactamide structures in one molecule is 10 or more (in the case of both the hydroxyl group and the lactamide structure, the total is 10 or more) water-soluble polymers. Examples of water-soluble polymers that impart wettability to the wafer surface include celluloses such as hydroxyethyl cellulose (HEC), hydroxypropyl cellulose, carboxymethyl cellulose, cellulose acetate, and methyl cellulose; Polyvinyl alcohol (PVA), polyvinylpyrrolidone (PVP), etc.; ethylene polymers, glycosides (glycosides), polyglycerol, etc. The two or more water-soluble polymers contained in the polishing composition are preferably free of poloxamine, poloxamer, polyoxyethylene methyl glucoside, polyoxyethylene propylidene, and methyl glucoside. One is selected from the group consisting of, and the other is selected from the group consisting of HEC, PVA, PVP, and polyglycerol. As for the two or more water-soluble polymers contained in the polishing composition, it is more preferable that one is poloxamine and the other is HEC. The polishing composition of the present embodiment may contain a chelating agent in addition to the above. The chelating agent is, for example, an aminocarboxylic acid-based chelating agent, an organic sulfonic acid chelating agent, and the like. Specific examples of the aminocarboxylic acid-based chelating agent include ethylenediaminetetraacetic acid, sodium ethylenediaminetetraacetate, nitrotriacetic acid, sodium nitrotriacetate, ammonium nitrotriacetate, and hydroxyethyl ethylene diacetate. Aminetriacetic acid, sodium hydroxyethylethylenediaminetriacetate, diethylenetriaminepentaacetic acid (DTPA), sodium diethylenetriaminepentaacetate, triethylenetetraminehexaacetic acid, triethylenetetramine Sodium amine hexaacetate, etc. Specific examples of the organic phosphonic acid-based chelating agent include 2-aminoethylphosphonic acid, 1-hydroxyethylidene-1,1-diphosphonic acid, aminotris(methylenephosphonic acid), ethyl Diaminetetra(methylenephosphonic acid), Diethylenetriaminepenta(methylenephosphonic acid), Ethane-1,1,-diphosphonic acid, Ethane-1,1,2-triphosphonic acid , ethane-1-hydroxy-1,1-diphosphonic acid, ethane-1-hydroxy-1,1,2-triphosphonic acid, ethane-1,2-dicarboxy-1,2-diphosphonic acid , methane hydroxyphosphonic acid, 2-phosphonobutane-1,2-dicarboxylic acid, 1-phosphonobutane-2,3,4-tricarboxylic acid, α-methylphosphonosuccinic acid, etc. . The polishing composition of the present embodiment may further contain a pH adjuster. The pH of the polishing composition of the present embodiment is preferably 8.0 to 12.0. In addition to the above, the polishing composition of the present embodiment can optionally mix additives commonly known in the field of polishing compositions. The polishing composition of the present embodiment is prepared by appropriately mixing abrasive grains, a basic compound, two or more water-soluble polymers, and other preparation materials, and adding water. Alternatively, the polishing composition of the present embodiment is prepared by sequentially mixing abrasive grains, a basic compound, two or more water-soluble polymers, and other preparation materials in water. As a method of mixing these components, a method commonly used in the technical field of polishing compositions such as a homogenizer and an ultrasonic wave can be used. The polishing composition described above is used for polishing a silicon wafer after being diluted with water so as to have an appropriate concentration. [Examples] Hereinafter, the present invention will be described more specifically with reference to examples. The present invention is not limited to these embodiments. [Polishing Example 1] The polishing compositions of Examples 1 to 4 shown in Table 1 and Comparative Examples 1 to 4 shown in Table 2 were prepared. [Table 1] [Table 2] The polishing composition of Example 1 contains colloidal silica with a particle size of 70 nm as abrasive particles, DTPA as a chelating agent, KOH and K 2 CO 3 as basic compounds, and poloxamine and HEC as water-soluble compounds. Sex polymers. The remainder of the grinding composition is water. The contents of abrasive grains, DTPA, KOH, K 2 CO 3 , poloxamine, and HEC were set to 3 wt %, 0.01 wt %, 0.3 wt %, 1 wt %, 0.0004 wt %, and 0.0004 wt %, respectively. The weight % concentration ratio of abrasive grains to poloxamide and the weight % concentration ratio of abrasive grains to HEC were both 1:0.0001. The polishing compositions of Examples 2 to 4 are based on the polishing composition of Example 1, the contents of poloxamine and HEC are changed, and the weight % concentration ratio of the abrasive particles to each water-soluble polymer is set as 1: 0.0003, 1: 0.0007, 1: 0.001. The polishing composition of Comparative Example 1 was based on the polishing composition of Example 1 without adding a water-soluble polymer. The polishing composition of Comparative Example 2 was based on the polishing composition of Example 1, the contents of poloxamine and HEC were changed, and the weight % concentration ratio of abrasive particles to each water-soluble polymer was set to 1: 0.0013 made. The polishing composition of Comparative Example 3 was based on the polishing composition of Example 4 without adding HEC. The polishing composition of Comparative Example 4 was based on the polishing composition of Example 4 without adding poloxamine. Using the polishing compositions of these Examples and Comparative Examples, the (100) surface of a P-type silicon wafer with a diameter of 300 mm was polished. The polishing device used SPP800S manufactured by Okamoto Machinery Manufacturing Co., Ltd. The polishing pad is a suede polishing pad. The polishing composition was diluted 10 times and supplied at a supply rate of 0.6 L/min. The rotational speed of the platen was set to 43 rpm, the rotational speed of the grinding head was set to 40 rpm, the grinding load was set to 0.012 MPa, and the grinding was performed for 4 minutes. After the polishing, the surface roughness Ra of the silicon wafer was measured using a non-contact surface roughness measuring machine (WycoNT9300, manufactured by Veeco Corporation). The evaluation of the wafer shape was performed using "difference GBIR" which will be described below. FIG. 1 is a diagram for explaining the differential GBIR. First, the distribution P1 of the thickness (distance from the back reference plane) of the silicon wafer before grinding is measured. Likewise, the thickness distribution P2 of the polished silicon wafer is measured. The difference between the distribution P1 before grinding and the distribution P2 after grinding was taken, and the distribution ΔP of "thickness removed by grinding (grinding amount)" was obtained. The difference between the maximum value ΔP max and the minimum value ΔP min of the distribution ΔP of the grinding amount in the region other than the specific edge region is defined as "difference GBIR". Wafer shape is evaluated using differential GBIR, whereby the polishing step itself can be performed more accurately by mitigating the influence of unevenness and unexpected factors of the silicon wafer before polishing, compared to the case where normal GBIR is used evaluation. The thickness distribution of the silicon wafer before and after polishing was measured using a wafer flatness inspection apparatus (Nonometro 300TT-A, manufactured by Kuroda Seiko Co., Ltd.). In addition, the average thickness of the grinding amount was divided by the grinding time to obtain the grinding rate. The polishing rate, the surface roughness Ra, and the difference GBIR are shown in Tables 1 and 2 above. The numerical values of polishing rate, surface roughness Ra, and difference GBIR in Tables 1 and 2 are relative values when the value of Comparative Example 1 (polishing composition without water-soluble polymer) is set as 100. In this evaluation, the polishing rate was 90 or more, the surface roughness Ra was 110 or less, and the difference GBIR was 70 or less as targets. As shown in Table 1, in Examples 1 to 5, the polishing rate was maintained at the same level as that of Comparative Example 1, and the surface roughness Ra and the difference GBIR were significantly improved. Comparing Examples 1 to 4, almost the same quality was obtained, but in the cases of Examples 1 and 2 in which the concentration of the water-soluble polymer with respect to the abrasive grains was relatively small, a tendency for the difference GBIR to become smaller was seen. As shown in Table 2, although the surface roughness Ra of the comparative example 2 was improved compared with the comparative example 1, the polishing rate fell. Also, the differential GBIR is not improved. The reason for this is considered to be that the concentration ratio of the water-soluble polymer to the abrasive grains is too high. In Comparative Examples 3 and 4, although the polishing rate was increased compared with that of Comparative Example 1, the improvement of the difference GBIR was insufficient. The reason for this is considered to be that these polishing compositions contain only one type of water-soluble polymer. [Polishing Example 2] Next, the polishing compositions of Comparative Examples 5 to 10 shown in Table 3 were prepared. [table 3] The polishing composition of Comparative Example 5 was the same as that of Comparative Example 1, based on the polishing composition of Example 1, without adding a water-soluble polymer. The polishing compositions of Comparative Examples 6 to 8 were based on the polishing composition of Comparative Example 4, the content of HEC was changed, and the weight % concentration ratio of abrasive grains to HEC was set to 1:0.0013, 1:0027, 1 : 0.005 is formed. The polishing composition of Comparative Example 9 is based on the polishing composition of Comparative Example 3, the content of poloxamine is changed, and the weight % concentration ratio of abrasive grains and poloxamine is set to 1:0.0013 By. The polishing composition of Comparative Example 10 was obtained by setting the weight % concentration ratio of abrasive grains to poloxamide and the weight % concentration ratio of abrasive grains to HEC to 1:0.0013. Using these polishing compositions, polishing was performed under conditions similar to those in Polishing Example 1. Then, in the same manner as in Polishing Example 1, the polishing rate, surface roughness Ra, and difference GBIR were determined. The results are shown in Table 3 above. The numerical values of polishing rate, surface roughness Ra, and difference GBIR in Table 3 are relative values when the value of Comparative Example 5 (polishing composition without water-soluble polymer) is set as 100. Compared with the comparative example 5, the improvement of the difference GBIR was not enough in the comparative example 6. In Comparative Examples 7 and 8, although the differential GBIR was improved, the polishing rate was greatly reduced. Compared with Comparative Example 5, the differential GBIR deteriorated in Comparative Example 9. In this way, when there is one type of water-soluble polymer, even if the content is adjusted, conditions that satisfy the three indicators of polishing rate, surface roughness Ra, and difference GBIR in a well-balanced manner cannot be obtained. Figures 2 to 5 show the results obtained by Comparative Example 5 (no water-soluble polymer), Comparative Example 9 (only poloxamide), Comparative Example 6 (only HEC), and Comparative Example 10 (combined use of poloxamine and HEC) ) distribution of the grinding amount of silicon wafers polished with the polishing composition. It can be seen from the comparison between FIG. 2 and FIG. 3 that poloxamide does not change the grinding amount at the center of the wafer, and reduces the grinding amount at the outermost periphery of the wafer. 2 and 4, it can be seen that HEC reduces the amount of grinding at the center of the wafer and increases the amount of grinding at the outermost periphery of the wafer. As shown in Fig. 5, by using poloxamide in combination with HEC, the variation of the grinding amount from the center of the wafer to the vicinity of the outer periphery is reduced, and the grinding amount can be adjusted between the center of the wafer and the position 100 mm from the center. Basically certain. [Polishing Example 3] Next, the polishing compositions of Examples 5 to 8 shown in Table 4, Examples 10 and 11 shown in Table 5, and Comparative Examples 11 to 13 were prepared. [Table 4] [table 5] The polishing compositions of Examples 5 to 7 were based on the polishing composition of Example 2, and were obtained by replacing HEC with other water-soluble polymers. Specifically, the polishing compositions of Examples 5 to 7 were obtained by replacing HEC with PVA, PVP, and polyglycerol, respectively. The polishing compositions of Examples 8 to 10 were based on the polishing composition of Example 2, and were obtained by replacing poloxamine with other water-soluble polymers. Specifically, the polishing compositions of Examples 8 to 10 were obtained by replacing poloxamine with poloxamer, polyoxyethylene methyl glucoside, and polyoxyethylene methyl glucoside, respectively. By. The polishing composition of Comparative Example 11 was the same as that of Comparative Example 1, based on the polishing composition of Example 1, without adding a water-soluble polymer. The polishing composition of Comparative Example 12 was based on the polishing composition of Comparative Example 4, changed the content of HEC, and set the weight % concentration ratio of abrasive grains to HEC to 1:0.002. The polishing composition of Comparative Example 13 is based on the polishing composition of Comparative Example 3, the content of poloxamine is changed, and the weight % concentration ratio of abrasive grains and poloxamine is set to 1:0.002 By. Using these polishing compositions, polishing was performed under conditions similar to those in Polishing Example 1. Then, in the same manner as in Polishing Example 1, the polishing rate, surface roughness Ra, and difference GBIR were determined. The results are shown in Table 4 and Table 5 above. The numerical values of polishing rate, surface roughness Ra, and difference GBIR in Tables 4 and 5 are relative values when the value of Comparative Example 11 (polishing composition without water-soluble polymer) is set as 100. In Examples 5 to 10, the polishing rate and the surface roughness Ra were equal to or more than that of Comparative Example 11, and the difference GBIR was greatly improved. In particular, in Example 5 (the water-soluble polymer is poloxamine and PVA) and Example 7 (the water-soluble polymer is poloxamine and polyglycerol), the grinding rate is also significantly improved. In Comparative Examples 12 and 13, the improvement of the differential GBIR was insufficient. The reason for this is considered to be that these polishing compositions contain only one type of water-soluble polymer. From the above results, it was confirmed that the shape of the polished wafer can be controlled at a high level by containing two or more water-soluble polymers in an appropriate amount in the polishing composition. The embodiments of the present invention have been described above. The above-described embodiments are merely examples for implementing the present invention. Therefore, the present invention is not limited to the above-described embodiment, and the above-described embodiment can be appropriately changed and implemented within a range that does not deviate from the gist.
