JPH10202522A - Polishing method - Google Patents
Polishing methodInfo
- Publication number
- JPH10202522A JPH10202522A JP1035797A JP1035797A JPH10202522A JP H10202522 A JPH10202522 A JP H10202522A JP 1035797 A JP1035797 A JP 1035797A JP 1035797 A JP1035797 A JP 1035797A JP H10202522 A JPH10202522 A JP H10202522A
- Authority
- JP
- Japan
- Prior art keywords
- polishing
- torque
- wafer
- progress
- polished
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
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Abstract
Description
【０００１】[0001]
【発明の属する技術分野】本発明は、半導体素子、磁性
素子、光学素子などの薄膜素子の製造工程において、平
板基板上に形成された薄膜の表面平坦化などに用いられ
る研磨方法に関し、特にＬＳＩ等の半導体素子の製造工
程においてシリコンウエハに形成された薄膜の表面平坦
化に用いられる研磨方法に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polishing method used for flattening the surface of a thin film formed on a flat substrate in a process of manufacturing a thin film device such as a semiconductor device, a magnetic device, and an optical device. The present invention relates to a polishing method used for flattening the surface of a thin film formed on a silicon wafer in a manufacturing process of a semiconductor device such as a semiconductor device.
【０００２】[0002]
【従来の技術】近年、例えばＬＳＩ等の半導体素子の製
造工程において、半導体素子の高密度化を目的として多
層配線が用いられるようになり、また半導体素子の微細
化に伴い配線形成の高精度化が要求されるようになって
きている。そのため、例えば層間絶縁膜や配線となる導
電膜をウエハ表面に形成した後、これらの薄膜の表面の
凹凸を化学的機械研磨（ＣＭＰ： Chemical Mechanical
Polishing）により平坦化することが行われるようにな
ってきている。2. Description of the Related Art In recent years, in the process of manufacturing semiconductor devices such as LSIs, multilayer wiring has been used for the purpose of increasing the density of semiconductor devices. Is being required. For this reason, for example, after an interlayer insulating film or a conductive film serving as a wiring is formed on the wafer surface, the unevenness on the surface of these thin films is removed by chemical mechanical polishing (CMP).
Polishing) has been performed.
【０００３】このウエハ表面の薄膜の研磨には、研磨台
上に載置されたウエハに、研磨定盤に取り付けられた研
磨パッドを押し当て、研磨スラリ（砥粒液）を供給しな
がら、研磨定盤および研磨台のいずれか一方または両方
を回転させる方法が採られてている。複数枚のウエハを
研磨台上に載置することにより、各ウエハを同時に研磨
することも行われる。To polish a thin film on the surface of a wafer, a polishing pad attached to a polishing table is pressed against a wafer placed on a polishing table, and polishing is performed while supplying a polishing slurry (abrasive liquid). A method of rotating one or both of the platen and the polishing table is employed. By mounting a plurality of wafers on a polishing table, each wafer is simultaneously polished.
【０００４】従来、このウエハ表面に形成されたの研磨
の終点検出は操業経験に基づき行われていた。すなわ
ち、研磨する薄膜の厚さをあらかじめ測定しておいた研
磨速度で除した値に安全率を乗じた値を研磨時間として
事前に設定しておき、その時間研磨を行う方法である。Conventionally, the end point of the polishing formed on the surface of the wafer has been detected based on operational experience. That is, a method in which a value obtained by dividing the thickness of the thin film to be polished by a previously measured polishing rate and a safety factor is set in advance as a polishing time, and polishing is performed for that time.
【０００５】しかしながら、研磨速度は研磨パッドの摩
耗や変形の影響を受ける。すなわち、研磨パッドが摩耗
すると急速に研磨速度が低下する。そのため、時間の経
過とともに、研磨パッドの摩耗度合いが大きくなり、研
磨時間を一定にしていたのではウエハの研磨不足等が発
生する。このため、あらかじめ研磨時間を設定する従来
方法では再現性良く研磨を行うことは困難であった。However, the polishing rate is affected by the wear and deformation of the polishing pad. That is, when the polishing pad is worn, the polishing rate is rapidly reduced. Therefore, as the time elapses, the degree of wear of the polishing pad increases, and if the polishing time is kept constant, insufficient polishing of the wafer occurs. For this reason, it has been difficult to perform polishing with good reproducibility by the conventional method in which the polishing time is set in advance.
【０００６】この問題点を解決する方法として、ウエハ
が固定されたホルダを回転駆動するトルクの時間変化を
測定することにより研磨終点を判定する方法が提案され
ている（特開平６−２１６０９５号公報、特開平６−３
１５８５０号公報）。As a method for solving this problem, there has been proposed a method of determining a polishing end point by measuring a time change of a torque for rotationally driving a holder to which a wafer is fixed (Japanese Patent Laid-Open No. 6-216095). JP-A-6-3
No. 15850).
【０００７】特開平６−２１６０９５号公報に記載され
た方法は、ウエハ表面に形成された薄膜の凹凸がなくな
るときの研磨抵抗の減少をトルクの急減としてとらえる
ものである。The method described in Japanese Patent Application Laid-Open No. 6-216095 captures a decrease in polishing resistance when the unevenness of the thin film formed on the wafer surface disappears as a sudden decrease in torque.
【０００８】また、特開平６−３１５８５０号公報に記
載された方法は、ウエハ表面に形成された薄膜が研磨さ
れて下地材料が表面に露出するときの研磨抵抗の変化を
トルクの変化としてとらえるものである。Further, the method described in Japanese Patent Application Laid-Open No. 6-315850 captures a change in polishing resistance when a thin film formed on a wafer surface is polished and a base material is exposed on the surface as a change in torque. It is.
【０００９】しかしながら、特開平６−２１６０９５号
公報に記載された方法では、半導体素子の微細パターン
の凹凸の減少による研磨抵抗の変化は微小であるため、
実際にはノイズなどのためにその研磨抵抗の変化をトル
クの変化として検出することは通常は困難である。However, in the method described in Japanese Patent Application Laid-Open No. 6-216095, a change in polishing resistance due to a decrease in unevenness of a fine pattern of a semiconductor element is very small.
In practice, it is usually difficult to detect a change in the polishing resistance as a change in torque due to noise or the like.
【００１０】また、特開平６−３１５８５０号公報に記
載された方法は、ウエハ表面の薄膜とは膜質の異なる下
地材料が表面に露出したときの研磨抵抗の変化をとらえ
るものであり、上述したウエハ表面に形成されたの凹凸
の平坦化のような薄膜を途中まで研磨する研磨工程、す
なわち下地材料が露出しない状態を研磨終了とする研磨
工程への適用は困難である。The method described in Japanese Patent Application Laid-Open No. Hei 6-315850 captures a change in polishing resistance when a base material having a different film quality from that of a thin film on a wafer surface is exposed on the surface. It is difficult to apply the present invention to a polishing step of polishing a thin film halfway, such as flattening of irregularities formed on the surface, that is, a polishing step of terminating polishing when a base material is not exposed.
【００１１】[0011]
【発明が解決しようとする課題】本発明は、上記の課題
を解決するためになされたものであり、ウエハ表面に形
成された薄膜の表面の凹凸の平坦化の研磨工程や研磨終
了の前に仕上げ研磨を行う研磨工程においても、研磨の
進行状況をモニタし、ウエハを再現性良く研磨できる研
磨方法を提供することを目的としている。SUMMARY OF THE INVENTION The present invention has been made in order to solve the above-mentioned problems, and it is desirable to provide a polishing step for flattening irregularities on the surface of a thin film formed on a wafer surface or a polishing step before completion of polishing. It is an object of the present invention to provide a polishing method capable of monitoring the progress of polishing in a polishing step of performing final polishing and polishing a wafer with good reproducibility.
【００１２】[0012]
【課題を解決するための手段】本発明の研磨方法は、研
磨パッドが被着された研磨定盤を回転させる回転軸およ
び被研磨物を回転させる回転軸の少なくとも一方のトル
クを測定し、研磨開始時点からのトルク積分値を演算
し、トルク積分値に基づいて研磨の進行状況をモニタす
ることを特徴としている（第一発明）。According to the polishing method of the present invention, the torque of at least one of a rotating shaft for rotating a polishing platen on which a polishing pad is attached and a rotating shaft for rotating an object to be polished is measured. The invention is characterized in that a torque integrated value from a start point is calculated, and a progress of polishing is monitored based on the torque integrated value (first invention).
【００１３】本発明の研磨方法は、第一発明の研磨方法
であって、前記トルク積分値に基づいて研磨終点または
仕上げ研磨の開始を判定することを特徴としている（第
二発明）。[0013] The polishing method of the present invention is the polishing method of the first invention, characterized in that a polishing end point or a start of finish polishing is determined based on the torque integrated value (second invention).
【００１４】なお、ここで言うトルク積分値は研磨開始
時点からのトルクの時間積分値であり、トルクをＴ
（ｔ）、研磨開始の時刻をｔ0 とすると、時刻ｔでのト
ルク積分値Ｓt は（１）式で表現される。ただし、ここ
で言うトルクは、トルク値である必要はなく、トルク相
当値を表す値であれば良い。Note that the torque integrated value referred to here is a time integrated value of the torque from the start of polishing.
(T), assuming that the polishing start time is t0, the torque integrated value St at the time t is expressed by equation (1). However, the torque mentioned here does not need to be a torque value, but may be a value representing a torque equivalent value.
【００１５】[0015]
【数１】 (Equation 1)
【００１６】本発明者は、研磨時の、研磨パッドと被研
磨物の摩擦による損失エネルギと研磨量との間に良好な
比例関係があることを見出した。また、研磨パッドと被
研磨物の摩擦による損失エネルギは被研磨物が研磨中に
受けた力積すなわちトルク積分値と良好な相関関係にあ
ることを見出した。The present inventor has found that there is a good proportional relationship between the loss energy due to friction between the polishing pad and the object to be polished during polishing and the amount of polishing. It has also been found that the energy loss due to friction between the polishing pad and the object to be polished has a good correlation with the impulse received by the object to be polished during polishing, that is, the torque integral value.
【００１７】したがって、研磨パッドが被着された研磨
定盤および被研磨物を回転させる回転軸の少なくとも一
方のトルクを測定しトルク積分値を演算することによ
り、研磨量を定量的に把握できる。その結果、トルク波
形の変化のあるなしに関わらず、トルク積分値から論理
的な研磨終点判定が可能となる。Accordingly, the amount of polishing can be quantitatively grasped by measuring the torque of at least one of the polishing platen on which the polishing pad is attached and the rotating shaft for rotating the object to be polished and calculating the torque integrated value. As a result, a logical polishing end point can be determined from the torque integrated value regardless of whether or not the torque waveform changes.
【００１８】すなわち、第一発明の研磨方法は、研磨開
始時点からのトルク積分値を演算し、トルク積分値に基
づいて研磨の進行状況をモニタするので、時々刻々研磨
量を定量的に把握できる。That is, in the polishing method according to the first aspect of the present invention, since the integrated torque value from the start of polishing is calculated and the progress of polishing is monitored based on the integrated torque value, the polishing amount can be quantitatively grasped every moment. .
【００１９】第二発明の研磨方法は、このトルク積分値
に基づいて研磨終点を判定する。その結果、ウエハ表面
に形成されたの表面の凹凸の平坦化のような、下地材料
が露出しない状態を研磨終了とする研磨工程、すなわち
研磨終了時に研磨する膜質が同一の研磨においても精度
良く研磨終点検出を行うことができ、ウエハを再現性良
く研磨できる。In the polishing method according to the second invention, the polishing end point is determined based on the torque integrated value. As a result, the polishing step of finishing the state where the underlying material is not exposed, such as the flattening of the unevenness of the surface formed on the wafer surface, that is, the polishing with high accuracy even in the polishing where the film quality to be polished at the end of the polishing is the same. The end point can be detected, and the wafer can be polished with high reproducibility.
【００２０】また、このトルク積分値に基づいて仕上げ
研磨の開始を判定する。その結果、研磨終了の前に仕上
げ研磨を行う研磨工程において仕上げ研磨の開始を正確
に判定できるので、ウエハを再現性良く研磨できる。ま
た、研磨工程に仕上げ研磨を正確にまた容易に組み込む
ことができるので、仕上げ研磨を組み込んで、研磨のウ
エハ面内均一性を向上させることが容易である。The start of finish polishing is determined based on the torque integrated value. As a result, the start of the finish polishing can be accurately determined in the polishing step of performing the finish polishing before the end of the polishing, so that the wafer can be polished with high reproducibility. In addition, since the final polishing can be accurately and easily incorporated into the polishing process, it is easy to incorporate the final polishing to improve the uniformity of the polishing in the wafer surface.
【００２１】[0021]
【発明の実施の形態】本発明の実施の形態について、Ｃ
ＭＰによる研磨方法を例にとり説明する。BEST MODE FOR CARRYING OUT THE INVENTION
The polishing method using MP will be described as an example.
【００２２】図１は、本発明の研磨方法に用いられる研
磨装置の１例を示す模式的縦断面図である。研磨パッド
２が研磨定盤５に取り付けられており、また、研磨台３
上にはウエハ載置部１が５ケ所設けられている。ウエハ
載置部１には、被研磨物であるウエハＳが載置される。
研磨定盤５は、その中心を回転軸として研磨定盤回転駆
動機構７により回転させられる。また、研磨台３および
ウエハ載置部１は、それぞれの中心を回転軸として、そ
れぞれが研磨台回転駆動機構４により回転させられる構
成となっている。すなわち、研磨台３がその中心軸の回
りに回転（公転）するとともに、ウエハ載置部１もウエ
ハ載置部１の中心軸の回りに回転（自転）する構成とな
っている。FIG. 1 is a schematic longitudinal sectional view showing an example of a polishing apparatus used in the polishing method of the present invention. A polishing pad 2 is attached to a polishing table 5 and a polishing table 3
On the upper side, five wafer mounting portions 1 are provided. A wafer S to be polished is placed on the wafer placement unit 1.
The polishing table 5 is rotated by a polishing table rotation drive mechanism 7 with its center as a rotation axis. Further, the polishing table 3 and the wafer mounting unit 1 are configured to be rotated by a polishing table rotation drive mechanism 4 with their respective centers as rotation axes. That is, the polishing table 3 rotates (revolves) around its central axis, and the wafer mounting section 1 also rotates (rotates) around the central axis of the wafer mounting section 1.
【００２３】ウエハＳの研磨は、研磨スラリ供給機構
（図示せず）から研磨スラリを供給しながら、研磨パッ
ド２とウエハＳとを接触回転させることにより行われ
る。この装置では、上述したようにウエハを５枚を同時
に研磨することができる。The polishing of the wafer S is performed by rotating the polishing pad 2 and the wafer S while supplying the polishing slurry from a polishing slurry supply mechanism (not shown). In this apparatus, five wafers can be simultaneously polished as described above.
【００２４】この装置では、さらに研磨定盤５のトルク
を測定するトルク測定機構８と研磨進行状況モニタ部９
が設けられている。In this apparatus, a torque measuring mechanism 8 for measuring the torque of the polishing table 5 and a polishing progress monitoring section 9 are further provided.
Is provided.
【００２５】トルク測定機構８は、トルクを測定し、ト
ルク測定信号を研磨進行状況モニタ部９に伝達する。ト
ルク測定機構８としては、例えば研磨定盤回転駆動機構
７の電動機に印加される電力を測定し、その電力値と研
磨定盤５の回転数とから算出するものなどを用いれば良
い。研磨定盤５の回転数を一定とする場合、その電力値
をそのまま用いても良い。また、トルク測定機構８とし
ては、この構成以外に、研磨定盤５と研磨定盤回転駆動
機構７の途中に市販のトルク測定器を挿入する構成とし
ても良い。The torque measuring mechanism 8 measures the torque and transmits a torque measurement signal to the polishing progress monitor 9. As the torque measuring mechanism 8, for example, a mechanism that measures electric power applied to the electric motor of the polishing platen rotation drive mechanism 7 and calculates the electric power value and the rotation speed of the polishing platen 5 may be used. When the rotation speed of the polishing table 5 is constant, the power value may be used as it is. In addition to the above configuration, the torque measuring mechanism 8 may be configured such that a commercially available torque measuring device is inserted in the middle of the polishing table 5 and the polishing table rotating drive mechanism 7.
【００２６】なお、トルクの測定は、この例では研磨定
盤５を駆動する回転軸に対するトルク対して行うもので
あるが、被研磨物を回転させる研磨台３の回転軸に対し
て行っても良いし、また両方に対して行っても良い。ま
た、それぞれのウエハ載置部１の回転軸に対して行って
も良い。In this example, the torque is measured with respect to the torque on the rotating shaft for driving the polishing table 5, but may be measured on the rotating shaft of the polishing table 3 for rotating the workpiece. Good, or both. Further, the measurement may be performed on the rotation axis of each wafer mounting unit 1.
【００２７】研磨進行状況モニタ部９は、研磨進行度演
算部９ａと終点判断部９ｂとを備えている。The polishing progress monitoring section 9 includes a polishing progress calculating section 9a and an end point judging section 9b.
【００２８】研磨進行度演算部９ａにおいては、トルク
測定信号に基づき研磨開始時から現時点までのトルク積
分値Ｓt が演算され、あらかじめ基準となる被研磨物に
対して研磨開始から終点まで演算しておいた基準トルク
積分値Ｓ0 に基づき、研磨進行度Ｐr が例えば（２）式
により演算される。In the polishing progress calculating section 9a, a torque integrated value St from the start of polishing to the present time is calculated based on the torque measurement signal, and a predetermined reference object to be polished is calculated from the start to the end of polishing. Based on the set reference torque integrated value S0, the polishing progress Pr is calculated by, for example, equation (2).
【００２９】 Ｐr＝（Ｓt／Ｓ0）×１００（％） ・・・（２） 終点判断部９ｂにおいては、この研磨進行度Ｐr などに
基づいて研磨終点や仕上げ研磨の開始が判定される。な
お、研磨終点の判定には、研磨進行度Ｐr が例えば１０
０（％）となった時点を研磨終点と判定することにすれ
ば良く、また仕上げ研磨の開始を判定には、研磨進行度
Ｐr が例えば９０（％）といった所定値となった時点を
仕上げ研磨の開始時間と判定するなどとすれば良い。Pr = (St / S0) × 100 (%) (2) The end point determining section 9b determines the polishing end point and the start of the finish polishing based on the polishing progress Pr and the like. For the determination of the polishing end point, the polishing progress Pr is, for example, 10
The point in time at which the polishing progress Pr reaches a predetermined value such as, for example, 90 (%) may be determined as the finish polishing. May be determined as the start time.
【００３０】以下、本発明の研磨方法について、フロー
チャートに基づき説明する。Hereinafter, the polishing method of the present invention will be described with reference to flowcharts.
【００３１】（第１の例）図２は、本発明の研磨方法の
第１の例を示すフローチャートである。この例は、ウエ
ハ表面に形成されたを目標量研磨して薄膜の表面の凹凸
を平坦化するものである。(First Example) FIG. 2 is a flowchart showing a first example of the polishing method of the present invention. In this example, the target formed on the wafer surface is polished to a target amount to flatten the unevenness on the surface of the thin film.
【００３２】あらかじめ、研磨するウエハと同じウエハ
に対して、表面を平坦化するために必要な研磨量に対応
する基準トルク積分値Ｓ0 を測定しておく。A reference torque integrated value S0 corresponding to the amount of polishing required to flatten the surface of the same wafer as the wafer to be polished is measured in advance.
【００３３】(1) 研磨進行状況モニタ部９に基準トルク
積分値Ｓ0 を入力する（ステップＳ２０１）。(1) The reference torque integrated value S0 is input to the polishing progress monitor 9 (step S201).
【００３４】(2) ウエハの研磨を開始する（ステップＳ
２０２）。(2) The polishing of the wafer is started (Step S)
202).
【００３５】(3) トルク測定機構８によりトルクＴを測
定する（ステップＳ２０３）。(3) The torque T is measured by the torque measuring mechanism 8 (step S203).
【００３６】(4) 研磨進行度演算部９ａにおいて、研磨
開始時から現時点までのトルク積分値Ｓt を演算する
（ステップＳ２０４）。(4) The polishing progress calculating section 9a calculates a torque integrated value St from the start of polishing to the present time (step S204).
【００３７】(5) 研磨進行度演算部９ａにおいて、トル
ク積分値Ｓt から研磨進行度Ｐr を例えば前述の（２）
式により演算する（ステップＳ２０５）。(5) The polishing progress calculating section 9a calculates the polishing progress Pr from the torque integrated value St, for example, as described in the above (2).
The calculation is performed using an equation (step S205).
【００３８】(6) 終点判定部９ｂにおいて、研磨進行度
Ｐr が１００（％）に到達したか否かにより終点を判定
する（ステップＳ２０６）。研磨進行度Ｐr が１００
（％）に到達したとき、研磨を終了する（ステップＳ２
０７）。研磨進行度Ｐr が１００（％）に到達していな
いとき、トルクＴ測定（ステップＳ２０３）に戻る。(6) The end point determination unit 9b determines the end point based on whether the polishing progress Pr reaches 100 (%) (step S206). Polishing progress Pr is 100
(%), The polishing is terminated (step S2).
07). When the polishing progress Pr has not reached 100 (%), the process returns to the torque T measurement (step S203).
【００３９】この研磨方法により、再現性良く、ウエハ
表面に形成されたを目標量だけ研磨して薄膜の表面の凹
凸を平坦化できる。According to this polishing method, it is possible to flatten the irregularities on the surface of the thin film by polishing the target formed on the wafer surface with good reproducibility.
【００４０】なお、基準トルク積分値Ｓ0 の決定は、研
磨するウエハと同じウエハに対し研磨量とトルク積分値
の関係を決定しておき、この関係を用いて目標研磨量に
対応する基準トルク積分値Ｓ0 を求めても良い。The reference torque integrated value S0 is determined by determining the relationship between the polishing amount and the torque integrated value for the same wafer as the wafer to be polished, and using this relationship to determine the reference torque integrated value corresponding to the target polishing amount. The value S0 may be determined.
【００４１】（第２の例）図３は、本発明の研磨方法の
第２の例を示すフローチャートである。この例は、第１
の例の研磨方法にさらに研磨終了の前に仕上げ研磨を加
えるものである。(Second Example) FIG. 3 is a flowchart showing a second example of the polishing method of the present invention. This example is the first
In the polishing method of the above example, finish polishing is further added before the polishing is completed.
【００４２】あらかじめ、第１の例と同様に、研磨する
ウエハと同じウエハに対して、表面を平坦化するために
必要な研磨量に対応するトルク積分値を測定するなどし
て、基準トルク積分値Ｓ0 を決定しておく。In the same manner as in the first example, a reference torque integration value is measured for the same wafer as the wafer to be polished by measuring a torque integration value corresponding to a polishing amount necessary for flattening the surface. The value S0 is determined in advance.
【００４３】また、仕上げ研磨開始の研磨進行度Ｐst
（以下、仕上げ開始進行度Ｐstと呼ぶ）を決定してお
く。仕上げ開始進行度Ｐstは、研磨の生産性と研磨のウ
エハ面内均一性との兼ね合いで決定すれば良い。仕上げ
開始進行度Ｐstを小さくすれば（仕上げ研磨開始を早め
れば）、研磨のウエハ面内均一性は向上するものの、仕
上げ研磨時の研磨速度は通常減少し研磨時間が長くな
り、研磨の生産性が低下するためである。The polishing progress rate Pst at the start of the final polishing is
(Hereinafter, referred to as a finishing start progress degree Pst). The finishing start degree Pst may be determined based on a balance between the polishing productivity and the uniformity of the polishing in the wafer surface. If the finish start progress degree Pst is reduced (the finish polishing start is advanced), the polishing uniformity in the wafer surface is improved, but the polishing rate during the finish polishing is usually decreased and the polishing time is lengthened, and the polishing production is increased. This is because the property is reduced.
【００４４】(1) 研磨進行状況モニタ部９に基準トルク
積分値Ｓ0 を入力する（ステップＳ３０１）。(1) The reference torque integrated value S0 is input to the polishing progress monitor 9 (step S301).
【００４５】(2) 研磨進行状況モニタ部９に仕上げ開始
進行度Ｐstを入力する（ステップＳ３０２）。(2) The finishing start progress degree Pst is input to the polishing progress monitoring section 9 (step S302).
【００４６】(3) ウエハの研磨を開始する（ステップＳ
３０３）。(3) The polishing of the wafer is started (Step S)
303).
【００４７】(4) トルク測定機構８によりトルクＴを測
定する（ステップＳ３０４）。(4) The torque T is measured by the torque measuring mechanism 8 (step S304).
【００４８】(5) 研磨進行度演算部９ａにおいて、研磨
開始時から現時点までのトルク積分値Ｓt を演算する
（ステップＳ３０５）。(5) The polishing progress calculating section 9a calculates the torque integrated value St from the start of polishing to the present time (step S305).
【００４９】(6) 研磨進行度演算部９ａにおいて、トル
ク積分値Ｓt に基づいて研磨進行度Ｐr を、例えば前述
の（２）式により演算する（ステップＳ３０６）。(6) The polishing progress calculating section 9a calculates the polishing progress Pr based on the torque integrated value St, for example, by the above-mentioned equation (2) (step S306).
【００５０】(7) 終点判定部９ｂにおいて、研磨進行度
Ｐr が仕上げ開始進行度Ｐstとなったか否かにより仕上
げ研磨開始を判定する（ステップＳ３０７）。研磨進行
度Ｐrが仕上げ開始進行度Ｐstに到達していないとき、
トルクＴ測定（ステップＳ３０４）に戻り、同じ条件で
研磨を続ける。研磨進行度Ｐr が仕上げ開始進行度Ｐst
に到達したとき、仕上げ研磨開始のステップへ移る（ス
テップＳ３０８）。(7) In the end point determining section 9b, the start of finish polishing is determined based on whether or not the polishing progress Pr has reached the finish start progress Pst (step S307). When the polishing progress Pr has not reached the finishing start progress Pst,
Returning to the measurement of the torque T (step S304), the polishing is continued under the same conditions. Polishing progress Pr is finishing start progress Pst
Is reached, the process proceeds to the step of starting the finish polishing (step S308).
【００５１】(8) 研磨条件を変更して、仕上げ研磨を開
始する（ステップＳ３０８）。(8) Finish polishing is started by changing the polishing conditions (step S308).
【００５２】例えば、研磨条件の変更は、トルクの変更
などによれば良い。トルクの変更による場合、研磨中に
トルクを減少するかもしくは増加するかは、研磨対象の
薄膜の膜質に依存して決めれば良い。例えば、シリコン
酸化膜の場合はトルクを減少した方がよく、タングステ
ン（Ｗ）の場合はトルクを増大させた方が、研磨のウエ
ハ面内均一性は向上する。For example, the polishing conditions may be changed by changing the torque. In the case of changing the torque, whether to decrease or increase the torque during polishing may be determined depending on the quality of the thin film to be polished. For example, in the case of a silicon oxide film, it is better to reduce the torque, and in the case of tungsten (W), increasing the torque improves the in-plane uniformity of polishing.
【００５３】(9) トルクＴを測定し、研磨進行度Ｐr を
演算する（ステップＳ３０４’、ステップＳ３０５’、
ステップＳ３０６’）。(9) Measure the torque T and calculate the polishing progress Pr (step S304 ', step S305',
Step S306 ′).
【００５４】(10)終点判定部９ｂにおいて、研磨進行度
Ｐr が１００（％）となったか否かにより終点を判定す
る（ステップＳ３０９）。研磨進行度Ｐr が１００
（％）に到達したとき、研磨を終了する（ステップＳ３
１０）。研磨進行度Ｐr が１００（％）に到達していな
いとき、トルクＴ測定（ステップＳ３０４’）に戻る。(10) The end point determination unit 9b determines the end point based on whether the polishing progress Pr has reached 100 (%) (step S309). Polishing progress Pr is 100
(%), The polishing is terminated (step S3).
10). When the polishing progress Pr has not reached 100 (%), the process returns to the torque T measurement (step S304 ').
【００５５】この研磨方法によれば、再現性良く、ウエ
ハ表面に形成されたを目標量研磨して薄膜の表面の凹凸
を平坦化できる。また、仕上げ研磨を正確にまた容易に
組み込むことができるので、研磨のウエハ面内均一性を
向上させることができる。According to this polishing method, the target formed on the wafer surface can be polished to a desired amount with good reproducibility and the unevenness on the surface of the thin film can be flattened. In addition, since the final polishing can be accurately and easily incorporated, the uniformity of the polishing in the wafer surface can be improved.
【００５６】[0056]
【実施例】本発明の実施例について説明する。本実施例
で用いた研磨装置は、図１に示したものである。トルク
の測定は、研磨定盤回転駆動機構７の電動機に印加され
る電力を測定して、その電力値と研磨定盤の回転数とか
ら演算することとした。An embodiment of the present invention will be described. The polishing apparatus used in this embodiment is that shown in FIG. The torque was measured by measuring the electric power applied to the electric motor of the polishing platen rotation drive mechanism 7 and calculating from the electric power value and the rotation speed of the polishing platen.
【００５７】この研磨装置を用いて表面に凹凸を有する
薄膜を備えたウエハを研磨したときのトルクの時間変化
を測定した。Using this polishing apparatus, the time change of the torque when a wafer provided with a thin film having irregularities on the surface was polished was measured.
【００５８】研磨に用いたウエハは、シリコンウエハ上
にシリコン酸化膜が凸部で５００ｎｍ凹部で３５０ｎｍ
成膜されたものであり、凹凸差は１５０ｎｍである。研
磨パッドは、不織布にポリウレタンを含浸させたものを
用いた。研磨スラリは、シリカ（ＳｉＯ2 ）をＫＯＨ水
溶液に懸濁させたものを用いた。研磨定盤５、研磨台
３、ウエハ載置部の回転数は、それぞれ４５ｒｐｍ、７
ｒｐｍ、４２ｒｐｍとした。The wafer used for polishing was such that a silicon oxide film was formed on a silicon wafer at a convex portion of 500 nm and at a concave portion of 350 nm.
The film was formed, and the unevenness difference was 150 nm. The polishing pad used was a nonwoven fabric impregnated with polyurethane. The polishing slurry used was a suspension of silica (SiO 2 ) in a KOH aqueous solution. The rotation speeds of the polishing table 5, the polishing table 3, and the wafer mounting portion are 45 rpm and 7 respectively.
rpm and 42 rpm.
【００５９】図４は、ウエハを研磨したときのトルクの
測定結果の一例を示す図である。シリコン酸化膜研磨中
は、顕著なトルク変化はなく、シリコン酸化膜が研磨除
去され下地のシリコンが露出した時点でトルクは大きく
増大する。すなわち、所定量だけシリコン酸化膜を研磨
して表面の凹凸を平坦化する場合に、トルク波形の変化
で終点を判定することは困難である。なお、図２中にト
ルク積分値Ｓt の１例を斜線部分で示す。FIG. 4 is a diagram showing an example of the measurement result of the torque when the wafer is polished. During the polishing of the silicon oxide film, there is no significant change in torque, and the torque greatly increases when the silicon oxide film is polished off and the underlying silicon is exposed. That is, when the silicon oxide film is polished by a predetermined amount to flatten the unevenness on the surface, it is difficult to determine the end point based on a change in the torque waveform. In FIG. 2, one example of the torque integrated value St is shown by hatching.
【００６０】摩耗度合いの異なる２種類の研磨パッドに
対して、研磨時間を変化させシリコン酸化膜の研磨量と
トルク積分値を測定することにより、シリコン酸化膜の
研磨量とトルク積分値の関係を調査した。研磨に用いた
ウエハおよび研磨条件は、上述のトルクの時間変化の測
定と同じである。The relationship between the polishing amount of the silicon oxide film and the integrated torque was measured by changing the polishing time and measuring the integrated amount of the silicon oxide film and the integrated torque of the two types of polishing pads having different degrees of wear. investigated. The wafer used for the polishing and the polishing conditions are the same as those in the measurement of the time change of the torque described above.
【００６１】図５は、シリコン酸化膜の研磨量とトルク
積分値との関係を示す図である。○は摩耗度合いの小さ
い研磨パッドで研磨を行った結果を、△は摩耗度合いの
大きい研磨パッドで研磨を行った結果を示す。研磨量と
トルク積分値は、研磨パッドの摩耗度合いに関わらず、
同一直線上にプロットされた。すなわち、同一の膜質の
薄膜を研磨する場合、研磨パッドの摩耗度合いなどの研
磨条件の変化によらず、トルク積分値を研磨量を表す指
標とできることが確認できた。FIG. 5 is a diagram showing the relationship between the polishing amount of the silicon oxide film and the torque integrated value. ○ indicates the result of polishing with a polishing pad having a small degree of wear, and △ indicates the result of polishing with a polishing pad having a large degree of wear. The polishing amount and torque integrated value are independent of the degree of wear of the polishing pad.
Plotted on the same line. In other words, it was confirmed that when polishing thin films having the same film quality, the torque integrated value can be used as an index representing the polishing amount regardless of changes in polishing conditions such as the degree of wear of the polishing pad.
【００６２】次に、図２に示したフローチャートに従っ
て、トルク積分値により研磨終点を判定する研磨方法を
行った。研磨に用いたウエハおよび研磨条件は、上述の
トルクの時間変化の測定と同じである。Next, in accordance with the flowchart shown in FIG. 2, a polishing method for determining the polishing end point based on the torque integrated value was performed. The wafer used for the polishing and the polishing conditions are the same as those in the measurement of the time change of the torque described above.
【００６３】シリコン酸化膜の目標研磨量を２５０ｎｍ
に決め、図５から研磨量２５０ｎｍに対応する研磨開始
から終点までの基準トルク積分値Ｓ0 を３１０００（Ｎ
・ｍ・sec）と決めた。すなわち、ウエハの研磨中にト
ルク積分値Ｓt を演算し、基準トルク積分値Ｓ0 に基づ
き研磨進行度Ｐr を演算して、研磨進行度Ｐr が１００
（％）となった時点を研磨終点と判定する手順とした。The target polishing amount of the silicon oxide film is set to 250 nm.
From FIG. 5, the reference torque integrated value S0 from the start of polishing to the end point corresponding to the polishing amount of 250 nm is 31000 (N
・ M ・ sec). That is, while the wafer is being polished, the torque integration value St is calculated, and the polishing progress Pr is calculated based on the reference torque integration value S0.
(%) Was determined as the polishing end point.
【００６４】摩耗度合いの異なる２種類の研磨パッドに
対して、それぞれウエハ２５枚を研磨した。Twenty-five wafers were polished for two types of polishing pads having different degrees of wear.
【００６５】その結果、摩耗度合いの小さい研磨パッド
に対しては、平均研磨量が２５１ｎｍで、均一性が±
５．０％、摩耗度合いの大きい研磨パッドに対しては、
平均研磨量が２４７ｎｍで、均一性が±４．４％であっ
た。すなわち、本発明法により、研磨条件によらず、目
標研磨量を研磨することができることを確認できた。As a result, for a polishing pad having a small degree of wear, the average polishing amount was 251 nm and the uniformity was ±
5.0%, for polishing pads with a high degree of wear,
The average polishing amount was 247 nm, and the uniformity was ± 4.4%. That is, it was confirmed that the target polishing amount can be polished by the method of the present invention regardless of the polishing conditions.
【００６６】さらに、図３に示したフローチャートに従
って、仕上げ研磨を含む研磨においてトルク積分値によ
り終点を判定する研磨方法を行った。研磨に用いたウエ
ハおよび研磨開始時の研磨条件は、上述のトルクの時間
変化の測定と同じである。ただし、仕上げ研磨の研磨条
件は、研磨定盤５の回転数は同一として、研磨パッドの
ウエハへの押圧力を減少させ、トルクをそれまで研磨し
ていたトルクの６０％まで減少させた。Further, in accordance with the flowchart shown in FIG. 3, in the polishing including the finish polishing, a polishing method for determining an end point by a torque integrated value was performed. The wafer used for polishing and the polishing conditions at the start of polishing are the same as those in the above-described measurement of the time change of the torque. However, the polishing conditions for the final polishing were such that the rotational speed of the polishing table 5 was the same, the pressing force of the polishing pad against the wafer was reduced, and the torque was reduced to 60% of the previously polished torque.
【００６７】仕上げ開始進行度Ｐstを、７０％（ケース
１）、８０％（ケース２）、９０％（ケース３）、１０
０％（ケース４）と変化させて、各５枚ウエハを研磨
し、シリコン酸化膜の研磨量およびウエハ面内均一性を
評価した。研磨量およびウエハ面内均一性は、ウエハ上
の複数点にてシリコン酸化膜の研磨量を測定し求めた。
なお、シリコン酸化膜の目標研磨量は３００ｎｍとし、
図５から研磨量３００ｎｍに対応する基準トルク積分値
Ｓ0を３７０００（Ｎ・ｍ・sec）と決めた。The finishing start progress rate Pst is set to 70% (case 1), 80% (case 2), 90% (case 3), 10%
Five wafers were polished while changing to 0% (Case 4), and the polishing amount of the silicon oxide film and the uniformity within the wafer surface were evaluated. The polishing amount and the uniformity within the wafer surface were determined by measuring the polishing amount of the silicon oxide film at a plurality of points on the wafer.
The target polishing amount of the silicon oxide film was set to 300 nm,
From FIG. 5, the reference torque integrated value S0 corresponding to the polishing amount of 300 nm was determined to be 37000 (N · m · sec).
【００６８】シリコン酸化膜の平均研磨量の平均値およ
び研磨量のウエハ面内均一性の平均値を表１に示す。Table 1 shows the average value of the average polishing amount of the silicon oxide film and the average value of the in-plane uniformity of the polishing amount.
【００６９】[0069]
【表１】 [Table 1]
【００７０】表１からわかるように、ケース１からケー
ス４のいずれのケースも、目標研磨量をほぼ研磨するこ
とができた。すなわち、トルク積分値を用いることによ
り、研磨途中でトルクを変更しても所定の厚みだけ研磨
することができることを確認できた。また、仕上げ研磨
を開始する時期を早めれば早めるほど（仕上げ開始進行
度Ｐstを小さくすればするほど）、研磨量のウエハ面内
均一性は向上した。As can be seen from Table 1, in each of Cases 1 to 4, the target polishing amount was almost polished. That is, it was confirmed that by using the torque integrated value, it was possible to polish a predetermined thickness even if the torque was changed during polishing. Further, the earlier the finish polishing is started (the smaller the finish start progress Pst), the more uniform the in-plane polishing amount is.
【００７１】[0071]
【発明の効果】上述したように、本発明の研磨方法は、
ウエハ表面に形成されたの表面の凹凸の平坦化のよう
な、下地材料が露出しない状態を研磨終了とする研磨工
程や研磨終了の前に仕上げ研磨を行う研磨工程において
も、研磨の進行状況をモニタして研磨の終点や仕上げ研
磨開始を適切に判定することができるので、ウエハを再
現性良く研磨することができる。As mentioned above, the polishing method of the present invention
In a polishing step in which the base material is not exposed, such as a flattening of surface irregularities formed on the wafer surface, a polishing step in which polishing is finished, or a polishing step in which finish polishing is performed before polishing is finished, the progress of polishing is also monitored. Since the end point of polishing and the start of finish polishing can be appropriately determined by monitoring, the wafer can be polished with good reproducibility.
【００７２】また、研磨進行度により研磨進行状況をモ
ニタできるので、研磨中に研磨トルクを任意に変更で
き、仕上げ研磨して研磨のウエハ面内均一性を向上させ
ることもできる。Since the progress of polishing can be monitored by the degree of progress of polishing, the polishing torque can be arbitrarily changed during polishing, and the uniformity of polishing can be improved in the wafer surface by performing final polishing.
【図１】本発明の研磨方法に用いられる研磨装置の１例
を示す模式的縦断面図である。FIG. 1 is a schematic longitudinal sectional view showing one example of a polishing apparatus used for a polishing method of the present invention.
【図２】本発明の研磨方法の第１の例を示すフローチャ
ートである。FIG. 2 is a flowchart showing a first example of the polishing method of the present invention.
【図３】本発明の研磨方法の第２の例を示すフローチャ
ートである。FIG. 3 is a flowchart showing a second example of the polishing method of the present invention.
【図４】ウエハを研磨したときのトルクの測定結果の一
例を示す図である。FIG. 4 is a diagram illustrating an example of a measurement result of a torque when a wafer is polished.
【図５】シリコン酸化膜の研磨量とトルク積分値との関
係を示す図である。FIG. 5 is a diagram showing a relationship between a polishing amount of a silicon oxide film and a torque integrated value.
Ｓ ウエハ（被研磨物） １ ウエハ載置部 ２ 研磨パッド ３ 研磨台 ４ 研磨台回転駆動機構 ５ 研磨定盤 ７ 研磨定盤回転駆動機構 ８ トルク測定機構 ９ 研磨進行状況モニタ部 ９ａ 研磨進行度演算部 ９ｂ 終点判定部 S Wafer (substrate to be polished) 1 Wafer mounting part 2 Polishing pad 3 Polishing table 4 Polishing table rotation drive mechanism 5 Polishing table 7 Polishing table rotation driving mechanism 8 Torque measurement mechanism 9 Polishing progress monitor 9a Polishing progress calculation Unit 9b End point judgment unit
Claims (2)
せる回転軸および被研磨物を回転させる回転軸の少なく
とも一方のトルクを測定し、研磨開始時点からのトルク
積分値を演算し、トルク積分値に基づいて研磨の進行状
況をモニタすることを特徴とする研磨方法。1. A method for measuring a torque of at least one of a rotating shaft for rotating a polishing platen to which a polishing pad is attached and a rotating shaft for rotating an object to be polished, and calculating a torque integrated value from a polishing start time; A polishing method characterized in that a progress of polishing is monitored based on a torque integrated value.
は仕上げ研磨の開始を判定することを特徴とする請求項
１記載の研磨方法。2. The polishing method according to claim 1, wherein a polishing end point or a start of finish polishing is determined based on the torque integrated value.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP1035797A JPH10202522A (en) | 1997-01-23 | 1997-01-23 | Polishing method |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP1035797A JPH10202522A (en) | 1997-01-23 | 1997-01-23 | Polishing method |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH10202522A true JPH10202522A (en) | 1998-08-04 |
Family
ID=11747930
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP1035797A Pending JPH10202522A (en) | 1997-01-23 | 1997-01-23 | Polishing method |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH10202522A (en) |
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2006093192A (en) * | 2004-09-21 | 2006-04-06 | Disco Abrasive Syst Ltd | Wafer polishing apparatus and wafer polishing method |
| US7132035B2 (en) * | 1998-09-03 | 2006-11-07 | Micron Technology, Inc. | Methods, apparatuses, and substrate assembly structures for fabricating microelectronic components using mechanical and chemical-mechanical planarization processes |
| TWI465317B (en) * | 2012-06-25 | 2014-12-21 | Sumco Corp | Polishing method of workpiece and polishing device of workpiece |
| CN107363712A (en) * | 2017-08-18 | 2017-11-21 | 清华大学 | Online end point determination control system and method for CMP process |
| CN117810110A (en) * | 2024-02-29 | 2024-04-02 | 江苏元夫半导体科技有限公司 | Detection window determining method and device |
| CN117810110B (en) * | 2024-02-29 | 2024-05-17 | 江苏元夫半导体科技有限公司 | Detection window determining method and device |
-
1997
- 1997-01-23 JP JP1035797A patent/JPH10202522A/en active Pending
Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7132035B2 (en) * | 1998-09-03 | 2006-11-07 | Micron Technology, Inc. | Methods, apparatuses, and substrate assembly structures for fabricating microelectronic components using mechanical and chemical-mechanical planarization processes |
| JP2006093192A (en) * | 2004-09-21 | 2006-04-06 | Disco Abrasive Syst Ltd | Wafer polishing apparatus and wafer polishing method |
| JP4615275B2 (en) * | 2004-09-21 | 2011-01-19 | 株式会社ディスコ | Wafer polishing apparatus and wafer polishing method |
| TWI465317B (en) * | 2012-06-25 | 2014-12-21 | Sumco Corp | Polishing method of workpiece and polishing device of workpiece |
| CN107363712A (en) * | 2017-08-18 | 2017-11-21 | 清华大学 | Online end point determination control system and method for CMP process |
| CN107363712B (en) * | 2017-08-18 | 2019-04-23 | 清华大学 | Online end point determination control system and method for CMP process |
| CN117810110A (en) * | 2024-02-29 | 2024-04-02 | 江苏元夫半导体科技有限公司 | Detection window determining method and device |
| CN117810110B (en) * | 2024-02-29 | 2024-05-17 | 江苏元夫半导体科技有限公司 | Detection window determining method and device |
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