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、哌六水合物、1-(2-胺基乙基)哌、N-甲基哌、哌鹽酸鹽、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 present inventors have conducted various studies in order to solve the above problems. As a result, the following findings were obtained. In order to control the shape of the polished wafer, it is effective to appropriately contain two or more kinds of water-soluble polymers in the polishing composition. Depending on the affinity of the two or more water-soluble polymers with the wafer, they act on the relatively inner region and the relatively outer region of the wafer, respectively. Furthermore, by appropriately controlling the concentration ratio of each of the two or more water-soluble polymers to the abrasive particles, the shape of the wafer can be controlled at a higher level without reducing the polishing speed. The present invention has been completed based on these findings. Hereinafter, a polishing composition according to an embodiment of the present invention will be described in detail. The polishing composition according to an 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 a silicon wafer. As the abrasive particles, 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 particles is not particularly limited, and is, for example, 0.1 to 15% by weight of the entire polishing composition. The content of the abrasive particles is preferably more from the viewpoint of increasing the polishing rate, and is preferably less from the viewpoint of reducing abrasive damage or foreign matter residue. The lower limit of the content of the abrasive particles is preferably 0.5% by weight, and more preferably 1% by weight. The upper limit of the content of the abrasive particles is preferably 12% by weight, and more preferably 10% by weight. The alkaline compound etches the surface of the wafer for chemical polishing. The basic compound is, for example, an amine compound or an inorganic basic compound. The amine compound is, for example, a primary amine, a secondary amine, a tertiary amine, a quaternary ammonium, a salt thereof, a heterocyclic amine, or the like. Specific examples include ammonia, tetramethylammonium hydroxide (TMAH), tetraethylammonium hydroxide (TEAH), tetrabutylammonium hydroxide (TBAH), methylamine, dimethylamine, trimethylamine, and ethylamine , Diethylamine, triethylamine, hexylamine, cyclohexylamine, ethylenediamine, hexamethylenediamine, diethylenetriamine (DETA), triethylenetetraamine, tetraethylethylenepentamine , Pentaethylhexylamine, monoethanolamine, diethanolamine, triethanolamine, N- (β-aminoethyl) ethanolamine, anhydrous piperazine, piperazine hydrate, 1- (2-aminoethyl) piperazine, N -Methylpiperazine, piperazine hydrochloride, guanidine carbonate, and the like. Examples of the inorganic basic compound include alkali metal hydroxides, alkali metal carbonates, alkali metal bicarbonates, alkaline earth metal hydroxides, alkaline earth metal carbonates, and alkaline earth metal bicarbonates. Specifically, the inorganic basic compound is potassium hydroxide (KOH), sodium hydroxide, potassium bicarbonate, potassium carbonate (K 2 CO 3 ), sodium bicarbonate, sodium carbonate, or the like. As the basic compound, alkali metal hydroxides, alkali metal carbonates, alkaline earth metal hydroxides, alkaline earth metal carbonates, quaternary ammonium, or quaternary ammonium in the groups of substances listed above can be preferably used. salt. As described above, the polishing composition of this embodiment can be preferably used for secondary polishing of a silicon wafer. As for the polishing composition for finishing polishing (final polishing), the purity requirement 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 Compared with the polishing composition, the polishing rate is required. Therefore, as the polishing composition for secondary polishing, it is preferable to use a basic compound having a strong chemical polishing effect. These basic compounds may be used alone or in combination of two or more. The total content of the basic compound is not particularly limited, and is, for example, 0.1 to 5 wt% 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 this embodiment contains two or more kinds of water-soluble polymers. The water-soluble polymer is adsorbed on the surface of the wafer, and the surface of the wafer is modified. Thereby, the uniformity of polishing 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); Ethylene polymers such as vinylpyrrolidone (PVP); glycosides (glycosides), polyethylene glycol, polypropylene glycol, polyglycerol, poloxamer, 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 the 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 kinds of water-soluble polymers to the abrasive particles is abrasive particles: water-soluble polymer = 1: 0.0001 to 1: 0.0010. If the water-soluble polymer becomes less than the 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, a target wafer shape cannot be obtained. On the other hand, if the water-soluble polymer becomes more than the abrasive grains: water-soluble polymer = 1: 0.0010, the polishing rate decreases. Moreover, the effects obtained by containing two or more water-soluble polymers cannot be fully 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 and the abrasive particles is preferably 0.0009 as the water-soluble polymer / abrasive particles, and more preferably 0.0007 as the water-soluble polymer / 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 two nitrogens of the alkylene diamine structure. A diamine compound having at least one block type polyether, and the block type polyether-based oxyethyl group and oxypropyl group are bonded (hereinafter referred to as "diamine having a block type polyether bonded" Compound "). [Chemical 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 Ethyl, PO represents oxypropyl, and a, b, and x are integers of 1 or more. The number a of oxyethene is preferably 1 to 500, and the number b of oxyethene is preferably 1 to 200. Preferably, the mass ratio of oxyethyl group to oxypropyl group is EO: PO = 10: 90 to 80:20. Specific examples of the diamine compound having a block-type polyether bonded include N, N, N ', N'-tetra-polyoxyethylene-polyoxypropylene-ethylenediamine (poloxacin amine). One of the water-soluble polymers is preferably HEC. As the 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, and 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 surface of a wafer means that the number of hydroxyl or lactam structures in a molecule is less than 10 (when both hydroxyl and lactam structures are present, the total is less than 10) Of water-soluble polymers. Examples of the water-soluble polymer that does not impart wettability to the wafer surface include poloxamer, polyoxyalkylene alkyl ether, polyoxyalkylene fatty acid ester, and Polyoxyalkylene alkylamines, and alkylene oxide derivatives of methylglucosides represented by the following general formula (6), polyol alkylene oxide adducts, polyol fatty acid esters, and polyethylene glycols , Polypropylene glycol, etc. [Chemical 2] (In the formula, AO represents alkylene oxide, and a to d represent integers.) Specifically, the polyoxyalkylene alkyl ether is polyoxyethylene lauryl ether, polyoxyethylene cetyl ether, and polyoxyalkylene. Ethyl stearyl ether. Specifically, polyoxyalkylene fatty acid esters are polyoxyethylene monolaurate, polyoxyethylene monostearate, and the like. Specifically, the polyoxyalkylene alkylamine is polyoxyethyl laurylamine, polyoxyethyl oleylamine, or the like. Examples of the alkylene oxide derivative of methylglucoside include polyoxyethylethylglucoside and polyoxypropylmethylglucoside. Specifically, polyhydric alcohol alkylene oxide adducts include alkylene oxide adducts of glycerol, pentaerythritol, and ethylene glycol. A water-soluble polymer that imparts wettability to the wafer surface means that the number of hydroxyl or lactam structures in a molecule is 10 or more (when both hydroxyl and lactam structures are present, the total is 10 or more) Of 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), polyglycerin, etc. The two or more water-soluble polymers contained in the polishing composition are preferably free poloxamer, poloxamer, polyoxyethyl ethyl glucoside, polyoxy propyl, methyl glucoside Choose one from the group, and choose another from the group consisting of HEC, PVA, PVP, and polyglycerin. It is more preferable that two or more kinds of water-soluble polymers contained in the polishing composition be poloxamer and the other is HEC. The polishing composition according to this 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, nitrogen triacetic acid, sodium nitrogen triacetate, ammonium nitrogen triacetate, and hydroxyethyl ethylene glycol. Amine triacetic acid, sodium hydroxyethyl ethylenediamine triacetate, diethylene triamine pentaacetic acid (DTPA), sodium diethylene triamine pentaacetate, triethylene tetraamine hexaacetic acid, triethylene tetramethyl Sodium amine hexaacetate and so on. Specific examples of the organic phosphonic acid-based chelating agent include 2-aminoethylphosphonic acid, 1-hydroxyethylene-1,1-diphosphonic acid, aminotris (methylenephosphonic acid), and ethyl Diamine tetra (methylenephosphonic acid), diethylene triaminepenta (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-methylphosphonic acid succinic acid, etc. . The polishing composition according to this embodiment may further include a pH adjuster. The pH of the polishing composition of this embodiment is preferably 8.0 to 12.0. In addition to the polishing composition of this embodiment, additives generally known in the field of polishing compositions can be arbitrarily formulated. The polishing composition of this embodiment is prepared by appropriately mixing abrasive grains, a basic compound, two or more kinds of water-soluble polymers, and other preparation materials and adding water. Alternatively, the polishing composition of this embodiment is prepared by sequentially mixing abrasive particles, basic compounds, two or more kinds of water-soluble polymers, and other preparation materials into water. As a method of mixing these components, a method commonly used in the technical field of a polishing composition such as a homogenizer and an ultrasonic wave can be used. The polishing composition described above is diluted with water so as to have an appropriate concentration, and then used for polishing a silicon wafer. [Examples] Hereinafter, the present invention will be described more specifically with reference to examples. The invention is not limited to these examples. [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 contained colloidal silica having a particle diameter of 70 nm as abrasive particles, DTPA as a chelating agent, KOH and K 2 CO 3 as basic compounds, and poloxamer and HEC as water-soluble compounds. Sex polymer. The remainder of the polishing composition is water. The content of the abrasive grains, DTPA, KOH, K 2 CO 3 , poloxamer, and HEC were set to 3% by weight, 0.01% by weight, 0.3% by weight, 1% by weight, 0.0004% by weight, and 0.0004% by weight, respectively. The weight-% concentration ratio of the abrasive particles and poloxamer, and the weight-% concentration ratio of the abrasive particles and HEC are both 1: 0.0001. The polishing composition of Examples 2 to 4 was based on the polishing composition of Example 1 and the content of poloxasamine and HEC was changed. The weight% concentration ratio of the abrasive particles to each water-soluble polymer was 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 and was not added with a water-soluble polymer. The polishing composition of Comparative Example 2 was based on the polishing composition of Example 1, and the content of poloxasamine and HEC was changed, and the weight% concentration ratio of the abrasive particles to each water-soluble polymer was set to 1: 0.0013 is made by. The polishing composition of Comparative Example 3 was based on the polishing composition of Example 4 and was not added with HEC. The polishing composition of Comparative Example 4 was based on the polishing composition of Example 4 and was not added with poloxamer. The polishing compositions of these examples and comparative examples were used to polish a P-type silicon wafer (100) surface with a diameter of 300 mm. The polishing device is SPP800S manufactured by Okamoto Machine Tool Works. The polishing pad is a polishing pad using suede. The polishing composition was diluted to 10 times, and was supplied at a supply rate of 0.6 L / min. The rotation speed of the platen was set to 43 rpm, the rotation speed of the grinding head was set to 40 rpm, the grinding load was set to 0.012 MPa, and grinding was performed for 4 minutes. After the polishing was completed, the surface roughness Ra of the silicon wafer was measured using a non-contact surface roughness measuring machine (WycoNT9300, manufactured by Veeco). The evaluation of the wafer shape was performed using the "difference GBIR" described below. FIG. 1 is a diagram for explaining the difference GBIR. First, the distribution P1 of the thickness (distance from the reference plane on the back surface) of the silicon wafer before polishing is measured. Similarly, the thickness distribution P2 of the polished silicon wafer was measured. Take the difference between the distribution P1 before polishing and the distribution P2 after polishing to obtain the distribution ΔP of "thickness (grinding amount) removed by polishing". The difference between the maximum value ΔP max and the minimum value ΔP min of the distribution ΔP of the grinding amount in a region other than the specific edge region is defined as a “difference GBIR”. Using differential GBIR to evaluate the shape of the wafer, compared with the case of using ordinary GBIR, the influence caused by unevenness and unexpected factors of the silicon wafer before polishing can be alleviated, and the polishing step itself can be performed more accurately 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 as the grinding rate. The polishing rate, surface roughness Ra, and difference GBIR are shown in Tables 1 and 2 above. The numerical values of the polishing rates, surface roughness Ra, and difference GBIR in Tables 1 and 2 are relative values when the value of Comparative Example 1 (a polishing composition containing no water-soluble polymer) was 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 shown in Table 1, in Examples 1 to 5, the polishing rate was maintained at the same as that of Comparative Example 1, and the surface roughness Ra and the difference GBIR were greatly improved. When Examples 1 to 4 are compared, approximately the same quality is obtained. However, in Examples 1 and 2 in which the concentration of the water-soluble polymer relative to the abrasive particles is relatively small, the difference GBIR tends to decrease. As shown in Table 2, although Comparative Example 2 had improved surface roughness Ra compared with Comparative Example 1, the polishing rate decreased. Moreover, the difference GBIR has not improved. This is considered to be because the concentration ratio of the water-soluble polymer to the abrasive particles is too high. Although Comparative Examples 3 and 4 had a higher polishing rate than Comparative Example 1, the improvement in the difference GBIR was insufficient. The reason is considered to be that these polishing compositions contain only one 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, and was based on the polishing composition of Example 1 without using a water-soluble polymer. The polishing compositions of Comparative Examples 6 to 8 were based on the polishing composition of Comparative Example 4 and changed the content of HEC, and the weight% concentration ratio of the abrasive particles to HEC was set to 1: 0.0013, 1: 0027, 1 : 0.005 Adults. The polishing composition of Comparative Example 9 was based on the polishing composition of Comparative Example 3, the content of poloxasamine was changed, and the weight percentage concentration ratio of the abrasive particles to poloxasamine was set to 1: 0.0013. By. The polishing composition of Comparative Example 10 was obtained by setting the weight% concentration ratio of the abrasive particles to poloxasin and the weight% concentration ratio of the abrasive particles to HEC to 1: 0.0013. Using these polishing compositions, polishing was performed under conditions similar to those of polishing example 1. Then, in the same manner as in Polishing Example 1, the polishing rate, the surface roughness Ra, and the difference GBIR were determined. The results are shown in Table 3 above. The numerical values of the polishing rate, surface roughness Ra, and difference GBIR in Table 3 are relative values when the value of Comparative Example 5 (a polishing composition containing no water-soluble polymer) was 100. Compared with Comparative Example 5, the improvement of the difference GBIR was insufficient. In Comparative Examples 7 and 8, although the difference GBIR was improved, the polishing rate was significantly reduced. Comparative Example 9 worsened the difference in GBIR compared to Comparative Example 5. In this way, when one kind of water-soluble polymer is used, even if the content is adjusted, it is impossible to obtain a condition that satisfactorily balances the three indexes of the polishing rate, the surface roughness Ra, and the difference GBIR. Figures 2 to 5 show the results of Comparative Example 5 (without water-soluble polymer), Comparative Example 9 (poloxamer only), Comparative Example 6 (HEC only), and Comparative Example 10 (combination of poloxamer and HEC). Distribution of the grinding amount of the silicon wafer on which the polishing composition was polished. According to the comparison between FIG. 2 and FIG. 3, it can be known that poloxamer does not change the grinding amount of the wafer center, and reduces the grinding amount of the outermost periphery of the wafer. According to the comparison between FIG. 2 and FIG. 4, it can be known that the HEC reduces the grinding amount of the wafer center and increases the grinding amount of the wafer outermost periphery. As shown in Figure 5, by using poloxamer and HEC together, the change in the amount of grinding between the center of the wafer and the periphery is reduced, and the amount of grinding can be adjusted between the center of the wafer and a 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 and Comparative Examples 11 to 13 shown in Table 5 were prepared. [Table 4] [table 5] The polishing compositions of Examples 5 to 7 were obtained by replacing the HEC with another water-soluble polymer based on the polishing composition of Example 2. Specifically, the polishing compositions of Examples 5 to 7 were obtained by replacing HEC with PVA, PVP, and polyglycerin, respectively. The polishing composition of Examples 8 to 10 was obtained by replacing the poloxamer with another water-soluble polymer based on the polishing composition of Example 2. Specifically, the polishing compositions of Examples 8 to 10 were obtained by replacing poloxamer with poloxamer, polyoxyethylethylglucoside, and polyoxymethylpropylglucoside, respectively. By. The polishing composition of Comparative Example 11 was the same as that of Comparative Example 1, and was based on the polishing composition of Example 1 without using a water-soluble polymer. The polishing composition of Comparative Example 12 was based on the polishing composition of Comparative Example 4, and the content of HEC was changed, and the weight% concentration ratio of the abrasive particles and HEC was set to 1: 0.002. The polishing composition of Comparative Example 13 was based on the polishing composition of Comparative Example 3, the content of poloxasamine was changed, and the weight% concentration ratio of the abrasive particles to poloxasamine was set to 1: 0.002. By. Using these polishing compositions, polishing was performed under conditions similar to those of polishing example 1. Then, in the same manner as in Polishing Example 1, the polishing rate, the surface roughness Ra, and the difference GBIR were determined. The results are shown in Tables 4 and 5 above. The numerical values of the polishing rate, surface roughness Ra, and difference GBIR in Tables 4 and 5 are relative values when the value of Comparative Example 11 (a polishing composition containing no water-soluble polymer) was 100. In Examples 5 to 10, the polishing rate and surface roughness Ra were equal to or higher than those of Comparative Example 11, and the difference GBIR was greatly improved. In particular, in Example 5 (water-soluble polymer is poloxamer and PVA) and Example 7 (water-soluble polymer is poloxamer and polyglycerin), the polishing rate is also significantly improved. The improvement of the difference GBIR of Comparative Examples 12 and 13 was insufficient. The reason is considered to be that these polishing compositions contain only one water-soluble polymer. From the above results, it was confirmed that by appropriately containing two or more water-soluble polymers in the polishing composition, the shape of the wafer after polishing can be controlled at a high level. The embodiments of the present invention have been described above. The above embodiments are merely examples for implementing the present invention. Therefore, the present invention is not limited to the above-mentioned embodiments, and the above-mentioned embodiments can be appropriately implemented without departing from the scope of the present invention.