JPH10229060A - Polishing amount measuring equipment - Google Patents
Polishing amount measuring equipmentInfo
- Publication number
- JPH10229060A JPH10229060A JP9029342A JP2934297A JPH10229060A JP H10229060 A JPH10229060 A JP H10229060A JP 9029342 A JP9029342 A JP 9029342A JP 2934297 A JP2934297 A JP 2934297A JP H10229060 A JPH10229060 A JP H10229060A
- Authority
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- Japan
- Prior art keywords
- polishing
- polished
- amount measuring
- light
- polishing amount
- 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.)
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- Constituent Portions Of Griding Lathes, Driving, Sensing And Control (AREA)
- Mechanical Treatment Of Semiconductor (AREA)
- Length Measuring Devices By Optical Means (AREA)
Abstract
Description
【０００１】[0001]
【発明の属する技術分野】本発明は、半導体プロセスで
使用されるCMP(Chemical Mechanical Polishing)装置の
終点検出方法または装置に関するものである。[0001] 1. Field of the Invention [0002] The present invention relates to an end point detection method or apparatus for a CMP (Chemical Mechanical Polishing) apparatus used in a semiconductor process.
【０００２】[0002]
【従来の技術】主にシリコンウエハ上の絶縁膜層および
金属配線層の平坦化に使用されるＣＭＰ（Chemical Mec
hanical Polishing：化学的機械研磨）装置では、平坦
化の方法に関係なく平坦化つまり、研磨をいつ終了させ
るかが重要となる。何故ならば、研磨が早く終了してし
まうと所望の平坦さが得られないという問題があり、ま
た、研磨をしすぎると研磨したくない領域を研磨してし
まうという問題があるからである。2. Description of the Related Art A CMP (Chemical Mec.) Used mainly for flattening an insulating film layer and a metal wiring layer on a silicon wafer.
In a hanical polishing (chemical mechanical polishing) apparatus, planarization, that is, when polishing is completed is important regardless of the method of planarization. This is because if polishing is completed early, there is a problem that a desired flatness cannot be obtained, and if polishing is performed too much, there is a problem that a region that is not desired to be polished is polished.
【０００３】一般的には、モニタウエハを使用し、オフ
ラインでモニタウエハの研磨量と研磨時間の関係を求め
ることによって、所望の研磨状態が得られる研磨時間を
決定し、この研磨時間によって研磨終点を管理してい
る。最近では、スループットの向上とコスト低減のため
にインラインでＣＭＰプロセスの終点検出を行う方法が
種々提案されてきた。Generally, a monitor wafer is used, and a relationship between a polishing amount and a polishing time of the monitor wafer is obtained off-line to determine a polishing time for obtaining a desired polishing state, and the polishing end point is determined by the polishing time. Is managing. Recently, various methods for in-line end point detection of the CMP process have been proposed to improve throughput and reduce cost.
【０００４】その方法としては、下地層の露出を用いる
方法、研磨した膜厚（研磨量）或いは研磨して残った膜
厚を測定する方法等である。具体的には、研磨面の平
坦化あるいは、研磨に伴い下地層が露出することによっ
てウエハキャリアを回転させるモーターのトルクが変動
することから、これをモニタして研磨終点を検出する方
法、の方法と同様に下地層の露出に伴いウエハキャ
リアの振動の周波数成分が変動することから、これをモ
ニタして研磨終点を検出する方法、研磨に伴い、定盤
とウエハの間の静電容量が変化することから、これをモ
ニタして研磨終点を検出する方法、研磨面側から研磨
面に光を照射して、研磨面での光の散乱状態をモニタし
て研磨終点を検出する方法等がある。[0004] As the method, there are a method using the exposure of the underlayer, a method of measuring the polished film thickness (polishing amount) or the film thickness remaining after polishing. Specifically, since the torque of the motor for rotating the wafer carrier varies due to the flattening of the polished surface or the exposure of the underlying layer accompanying the polishing, a method of monitoring this and detecting the polishing end point. In the same way as above, the frequency component of the vibration of the wafer carrier fluctuates with the exposure of the underlayer, so the method of monitoring this and detecting the polishing end point changes the capacitance between the surface plate and the wafer with polishing. Therefore, there is a method of detecting the polishing end point by monitoring this, a method of irradiating the polishing surface with light from the polishing surface side, and monitoring the scattering state of light on the polishing surface to detect the polishing end point. .
【０００５】[0005]
【発明が解決しようとする課題】しかしながら、従来の
トルク変動や振動、静電容量を用いる方法は、本来不要
なストップ層の形成や配線が必要になるという問題が有
り、また、精度が十分でないという問題や、研磨面内で
の研磨速度にむらがある場合に部分的に研磨が不十分に
もかかわらず研磨の終点と判定してしまうという問題が
あった。However, the conventional method using torque fluctuation, vibration, and capacitance has a problem that an unnecessary stop layer and wiring are required, and the accuracy is not sufficient. In addition, there is a problem that when there is unevenness in the polishing rate within the polishing surface, the polishing is determined to be the end point of polishing even though the polishing is partially insufficient.
【０００６】本発明は研磨対象の材質に影響せず精度の
高い終点検出を行うことの可能な研磨量測定装置を提供
することを目的とする。An object of the present invention is to provide a polishing amount measuring apparatus capable of detecting an end point with high accuracy without affecting a material to be polished.
【０００７】[0007]
【課題を解決するための手段】上記の問題を解決するた
めに本発明の研磨量測定装置は、定盤上に配置した研磨
布上に被研磨物を接触させ、かつ相対運動させることに
よって、被研磨物を研磨する装置に用いられる研磨量測
定装置であって、被研磨物の研磨布と接触する研磨面へ
照明光を供給し、所定のスポット径を有する光スポット
を形成する照明光学系と、対物レンズを含む観察光学系
と、観察光学系に関して研磨面とほぼ共役な面に配置さ
れ光スポットが形成された領域の研磨面の変化を検出す
る２次元センサと、２次元センサから出力される研磨面
の変化に応じた信号の変化から研磨面が平坦になったこ
とを検出する平坦検出手段と、を有する。SUMMARY OF THE INVENTION In order to solve the above problems, a polishing amount measuring apparatus according to the present invention is provided by bringing an object to be polished into contact with a polishing cloth arranged on a surface plate and causing relative movement thereof. A polishing amount measuring device used in a device for polishing an object to be polished, which supplies illumination light to a polishing surface of the object to be polished in contact with a polishing cloth to form a light spot having a predetermined spot diameter. An observation optical system including an objective lens, a two-dimensional sensor arranged on a surface substantially conjugate to the polished surface with respect to the observation optical system, for detecting a change in the polished surface in a region where a light spot is formed, and an output from the two-dimensional sensor. Flatness detecting means for detecting that the polished surface has become flat from a change in a signal corresponding to the change in the polished surface.
【０００８】[0008]
【発明の実施の形態】図１は本発明の第１の実施形態に
よる研磨量測定装置をＣＭＰ装置に組み込んだ概略構成
図であり、図２は図１に示される研磨料測定装置の概略
構成図である。これらの図で同一の構成要素は、同じ符
号で示してある。シリコンウエハ１は、バッキングパッ
ド２を介し、ウエハキャリア５によって保持され、定盤
３の上に固定された研磨布４に押しつけられている。ウ
エハキャリア５は、軸６を中心に自転し、更に定盤３も
軸７を中心に自転する。尚、本実施の形態ではウエハ１
はいわゆる真空チャックによってバッキングパッド２を
介してウエハキャリア５の下面に保持されている。DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a schematic configuration diagram in which a polishing amount measuring device according to a first embodiment of the present invention is incorporated in a CMP device, and FIG. 2 is a schematic configuration of the polishing material measuring device shown in FIG. FIG. In these figures, the same components are denoted by the same reference numerals. The silicon wafer 1 is held by a wafer carrier 5 via a backing pad 2 and pressed against a polishing cloth 4 fixed on a surface plate 3. The wafer carrier 5 rotates around a shaft 6, and the platen 3 also rotates around a shaft 7. In this embodiment, the wafer 1
Is held on the lower surface of the wafer carrier 5 via the backing pad 2 by a so-called vacuum chuck.
【０００９】ウエハキャリア５およびバッキングパッド
２の一部に貫通孔を設け、そこに研磨量測定装置８が設
けられている。図１のＣＭＰ装置では３つの研磨量測定
装置８が設けられている。図２に示すように、研磨量測
定装置８は照明用光源９、第１の集光レンズ１０、視野
絞り１１、コンデンサレンズ１２、ハーフミラー１３、
対物レンズ１４、第２の集光レンズ１５、光路分割用ハ
ーフプリズム１６、イメージセンサ（２次元センサ）１
７、コントラストを検出し合焦信号を出力する焦点検出
回路１８、焦点検出回路１８の出力を元に駆動される対
物レンズ用アクチュエータ１９から構成されている。ア
クチュエータ１９としては例えばピエゾ素子等の圧電素
子を用いることができる。A through-hole is provided in a part of the wafer carrier 5 and the backing pad 2, and a polishing amount measuring device 8 is provided therein. In the CMP apparatus of FIG. 1, three polishing amount measuring devices 8 are provided. As shown in FIG. 2, the polishing amount measuring device 8 includes an illumination light source 9, a first condenser lens 10, a field stop 11, a condenser lens 12, a half mirror 13,
Objective lens 14, second condenser lens 15, optical path splitting half prism 16, image sensor (two-dimensional sensor) 1
7. A focus detection circuit 18 for detecting contrast and outputting a focus signal, and an objective lens actuator 19 driven based on the output of the focus detection circuit 18. As the actuator 19, for example, a piezoelectric element such as a piezo element can be used.
【００１０】光源９はシリコンウエハ１を透過する波長
の赤外光を発する。光源９を出た光は第１の集光レンズ
１０によって集光され、集光された光は視野絞り１１に
よって余分な光が遮られる。視野絞り１１を透過した光
はコンデンサレンズ１２を通り、ハーフミラー１３で反
射し、対物レンズ１４によって被研磨面２０に集光され
る。研磨面２０で反射した光は再びシリコンウェハ１を
透過し、対物レンズ１４、ハーフミラー１３、第２の集
光レンズ１５を通って光路分割ハーフプリズム１６で２
つの光束２１、２２に分割された後、イメージセンサ１
７に入射する。イメージセンサ１７は光束２１、２２に
対して、それぞれ後ピン、前ピンの位置にあり、コント
ラスト検出を用いた周知の方法により合焦信号を取り出
す働きをする。すなわち、イメージセンサ１７上に形成
される後ピン及び前ピンの研磨面２０の像のコントラス
ト（光強度）を検出し、比較することにより焦点検出回
路１８は合焦用信号２３を出力し、この信号に基づいて
アクチュエータ１９が作動し、対物レンズ１４が光軸方
向に移動して自動的に合焦状態が達成される。尚、この
コントラスト検出の方法は例えば特開昭５９−２３２３
０６号公報に開示されている。これにより、シリコンウ
ェハ１やバッキングパッド２の厚さが異なる場合でも常
にシリコンウェハ１の研磨面２０が研磨量測定装置８の
対物レンズ１４の焦点位置に維持される。The light source 9 emits infrared light having a wavelength transmitting through the silicon wafer 1. The light emitted from the light source 9 is collected by the first condenser lens 10, and the collected light is blocked by a field stop 11 from excess light. Light transmitted through the field stop 11 passes through the condenser lens 12, is reflected by the half mirror 13, and is condensed on the surface 20 to be polished by the objective lens 14. The light reflected on the polished surface 20 passes through the silicon wafer 1 again, passes through the objective lens 14, the half mirror 13, and the second condenser lens 15 and is split by the optical path splitting half prism 16
After being split into two light fluxes 21 and 22, the image sensor 1
7 is incident. The image sensor 17 is located at the positions of the rear focus and the front focus with respect to the light beams 21 and 22, respectively, and functions to extract a focus signal by a known method using contrast detection. That is, the focus detection circuit 18 outputs a focusing signal 23 by detecting and comparing the contrast (light intensity) of the image of the polished surface 20 of the rear pin and the front pin formed on the image sensor 17. The actuator 19 operates based on the signal, and the objective lens 14 moves in the direction of the optical axis, thereby automatically achieving a focused state. The method of detecting the contrast is described in, for example,
No. 06 is disclosed. Thus, even when the thickness of the silicon wafer 1 or the backing pad 2 is different, the polishing surface 20 of the silicon wafer 1 is always maintained at the focal position of the objective lens 14 of the polishing amount measuring device 8.
【００１１】尚、光束２１は光路分割用ハーフプリズム
１６の分割面１６ａによってその一部が光束２８として
分離される。イメージセンサ１７は光束２８に対して合
焦位置にあり、研磨面２０の像を検出する。さらに、イ
メージセンサ１７からの信号により信号処理回路２４で
信号処理を行い研磨の進行状態を検出し、研磨の終点を
検出する。この終点検出方法について図３を用いて説明
する。図３は研磨の進行ごとのシリコンウェハ１の研磨
面２０の形状変化を示す断面図である。The light beam 21 is partly separated as a light beam 28 by the splitting surface 16a of the optical path splitting half prism 16. The image sensor 17 is at a focus position with respect to the light beam 28 and detects an image on the polished surface 20. Further, the signal processing circuit 24 performs signal processing based on a signal from the image sensor 17 to detect the progress of polishing, and detects the end point of polishing. This end point detection method will be described with reference to FIG. FIG. 3 is a cross-sectional view showing a shape change of the polished surface 20 of the silicon wafer 1 as the polishing progresses.
【００１２】研磨面２０に集光される光源９の光は所定
のスポットサイズ径を有している。このスポット径サイ
ズは研磨が行われるデバイスのデザインルールによって
選択され、照明される光のスポットの中にデバイスのパ
ターン領域が存在するように設定される。本実施形態で
はこのスポット径サイズを１０μｍとした。また、スポ
ット径のサイズは光源９と研磨面２０との間に配置され
る照明光学系によって任意の大きさにすることが可能で
ある。The light of the light source 9 condensed on the polished surface 20 has a predetermined spot size diameter. The spot diameter size is selected according to the design rule of the device to be polished, and is set so that the pattern region of the device exists in the spot of the light to be illuminated. In the present embodiment, the spot diameter size is set to 10 μm. Further, the size of the spot diameter can be arbitrarily set by an illumination optical system disposed between the light source 9 and the polishing surface 20.
【００１３】図３（ａ）はこの光スポットで照明されて
いるデバイスの領域を断面図で示した。シリコンウェハ
１の表面に透明絶縁膜２５が形成されている。この図で
は上面が研磨面２０となっている。透明絶縁膜２５の材
料にはＳｉＯ2等が用いられる。この透明絶縁膜２５を
研磨し、平滑にする。図３（ａ）は研磨開始前の様子を
表している。この時の光束２８に対するイメージセンサ
１７からの信号を図４（ａ）に示す。透明絶縁膜２５の
段差部で光が散乱し反射光量が低下している。研磨を進
めると、シリコンウェハ１の研磨面２０は図３（ｂ）の
ようになり、透明絶縁膜２５の段差が小さくなり、その
時のイメージセンサ１７からの信号（図４（ｂ））も段
差が小さくなるため段差部での光の散乱が小さくなり、
反射光量の低下も小さくなる。さらに研磨が進むと図３
（ｃ）のように透明絶縁膜２５の段差が無くなる。その
時のイメージセンサ１７からの信号（図４（ｃ））は段
差部での光の散乱が無くなるため、信号も平らになる。
そして、信号処理回路２４によってイメージセンサ１７
の信号を信号処理し研磨の終点を判断する。FIG. 3 (a) shows in cross section the area of the device which is illuminated with this light spot. A transparent insulating film 25 is formed on the surface of the silicon wafer 1. In this figure, the upper surface is the polishing surface 20. The material of the transparent insulating film 25 is, for example, SiO 2 . The transparent insulating film 25 is polished and smoothed. FIG. 3A shows a state before the start of polishing. FIG. 4A shows a signal from the image sensor 17 for the light beam 28 at this time. Light is scattered at the steps of the transparent insulating film 25, and the amount of reflected light is reduced. As the polishing proceeds, the polished surface 20 of the silicon wafer 1 becomes as shown in FIG. 3B, the step of the transparent insulating film 25 is reduced, and the signal from the image sensor 17 at that time (FIG. 4B) is also changed. Light scattering at the step is reduced,
The decrease in the amount of reflected light is also small. As the polishing progresses further, FIG.
As shown in (c), the step of the transparent insulating film 25 is eliminated. At this time, the signal from the image sensor 17 (FIG. 4C) is flat because the scattering of light at the step is eliminated.
Then, the image sensor 17 is operated by the signal processing circuit 24.
Is processed to determine the end point of polishing.
【００１４】図１のようにシリコンウェハ１内の複数の
場所に研磨量測定装置８を設けることにより、シリコン
ウェハ内の異なる箇所での研磨の状況を把握することが
でき、シリコンウェハ面内で研磨速度にむらが発生した
場合でも、終点の検出を正確に行うことができる。な
お、研磨量測定装置８において最初にシリコンウェハ１
の研磨面２０に対物レンズ１４の焦点を合わせる場合、
研磨量測定装置８の光路を分岐し、ＣＣＤカメラで、対
物レンズ１４の焦点位置の像を観察できる構成にしてお
くと、研磨面２０に対物レンズ１４の焦点を合わせるの
が容易となる。By providing the polishing amount measuring devices 8 at a plurality of locations in the silicon wafer 1 as shown in FIG. 1, the polishing conditions at different locations in the silicon wafer can be grasped, and The end point can be detected accurately even when the polishing speed is uneven. In the polishing amount measuring device 8, first, the silicon wafer 1
When the objective lens 14 is focused on the polished surface 20 of
If the optical path of the polishing amount measuring device 8 is branched so that an image of the focal position of the objective lens 14 can be observed with a CCD camera, it becomes easy to focus the objective lens 14 on the polishing surface 20.
【００１５】尚、本実施形態では光スポット内のデバイ
スにおける光の散乱をイメージセンサ１７において検出
される光強度の変化で検出するため、光スポット内で光
強度の変化が生じると精度よく研磨の終点検出を行うこ
とが出来ない。従って、この場合は光スポット内を均一
に照明するか、信号処理回路２４にて補正することが好
ましい。In this embodiment, since the scattering of light in the device in the light spot is detected by the change in the light intensity detected by the image sensor 17, if the change in the light intensity occurs in the light spot, the polishing is accurately performed. The end point cannot be detected. Therefore, in this case, it is preferable to uniformly illuminate the inside of the light spot or to make correction in the signal processing circuit 24.
【００１６】本実施形態では光スポットサイズをパター
ン領域がほぼ入るような所定の大きさにしたため、光ス
ポットの走査をせずとも常に散乱光の検出が行うことが
できる。また、本実施形態では明視野で観察を行った
が、散乱の程度が低い場合には暗視野で観察を行うと精
度良く散乱光の検出を行うことができる。In the present embodiment, the light spot size is set to a predetermined size such that the pattern area is substantially included, so that scattered light can always be detected without scanning the light spot. In the present embodiment, observation is performed in a bright field. However, when the degree of scattering is low, observation in a dark field allows accurate detection of scattered light.
【００１７】本実施形態では前ピン、後ピン及び合焦位
置の被研磨面２０の像を検出するために１つのイメージ
センサ１７を用いたが、勿論それぞれを別のイメージセ
ンサで観察することも可能である。また、イメージセン
サ１７で検出される前ピンまたは後ピンの像のボケが被
研磨面２０における散乱光を十分に検出できる程度であ
れば光束２８を作らずに光束２１または光束２２のどち
らかの検出結果を用いて終点検出を行うことが出来る。
また、本実施形態では常に焦点検出を行って焦点位置の
ずれを補正することができるので研磨等に伴って研磨面
が焦点位置からずれた場合においても正確に終点検出を
行うことが可能となる。In the present embodiment, one image sensor 17 is used to detect images of the front pin, the rear pin, and the image of the polished surface 20 at the in-focus position. It is possible. Further, if the blur of the image of the front pin or the rear pin detected by the image sensor 17 is such that the scattered light on the surface to be polished 20 can be sufficiently detected, either the light flux 21 or the light flux 22 is not generated without generating the light flux 28. The end point can be detected using the detection result.
Further, in the present embodiment, since the focus position can always be detected to correct the deviation of the focal position, the end point can be accurately detected even when the polished surface deviates from the focal position due to polishing or the like. .
【００１８】また、本実施形態では被研磨物であるシリ
コンウェハ１を保持するウエハキャリア５に研磨量測定
装置８を設けているため、常にシリコンウエハ１の同じ
位置の終点検出を行うことが出来る。図５は本発明の第
２の実施形態による研磨量測定装置を示す概略構成図で
ある。第１の実施形態と同様な構成要素には同じ符号を
つけて説明を省略する。In this embodiment, since the polishing amount measuring device 8 is provided on the wafer carrier 5 which holds the silicon wafer 1 to be polished, the end point of the same position on the silicon wafer 1 can be always detected. . FIG. 5 is a schematic configuration diagram showing a polishing amount measuring apparatus according to a second embodiment of the present invention. The same components as those in the first embodiment are denoted by the same reference numerals, and description thereof is omitted.
【００１９】第２の実施形態ではシリコンウェハ１の表
面に金属膜が形成されている。金属膜は光を吸収するの
で、第１の実施形態のようにシリコンウェハの裏面から
光を導入して測定することができない。そこで、第２の
実施形態では定盤３、研磨布４に貫通穴を設けて、その
部分に研磨量測定装置８からの光が透過するようにす
る。また、第２の実施形態では照明光がシリコンウェハ
１を透過しないので光源９には赤外光以外の波長の光を
発する光源を用いることができる。その他の構成、およ
び動作は第１の実施形態と同じであるため説明を省略す
る。In the second embodiment, a metal film is formed on the surface of the silicon wafer 1. Since the metal film absorbs light, measurement cannot be performed by introducing light from the back surface of the silicon wafer as in the first embodiment. Therefore, in the second embodiment, through holes are provided in the surface plate 3 and the polishing cloth 4 so that light from the polishing amount measuring device 8 is transmitted therethrough. In the second embodiment, since the illumination light does not pass through the silicon wafer 1, a light source that emits light having a wavelength other than infrared light can be used as the light source 9. The other configuration and operation are the same as those of the first embodiment, and thus the description is omitted.
【００２０】第２の実施形態でも研磨中に研磨布の厚さ
が研磨による磨耗によって変化し、研磨量測定装置８と
シリコンウェハの研磨面２０の位置がずれても、常にシ
リコンウェハ１の研磨面２０が研磨量測定装置８の対物
レンズ１４の焦点位置に維持される。さらに、イメージ
センサ１７からの信号により信号処理回路２４により研
磨の進行状態を検出し、研磨の終点を検出する。この終
点検出方法について図６を用いて説明する。Also in the second embodiment, even when the thickness of the polishing cloth changes due to abrasion due to polishing during polishing, and the position of the polishing amount measuring device 8 and the polishing surface 20 of the silicon wafer are shifted, the polishing of the silicon wafer 1 is always performed. The surface 20 is maintained at the focal position of the objective lens 14 of the polishing amount measuring device 8. Further, the progress of polishing is detected by the signal processing circuit 24 based on a signal from the image sensor 17, and the end point of polishing is detected. This end point detection method will be described with reference to FIG.
【００２１】図６は研磨の進行ごとの研磨面２０の形状
変化の示す断面図である。シリコンウェハ１の表面に金
属膜２６が形成されている。金属膜２６の材料にはＡｌ
やＴｉ等が用いられる。この金属膜２６を研磨し、表面
を平滑にする。図６（ａ）は研磨開始前の様子を表して
いる。その時のイメージセンサ１７からの信号を図７
（ａ）に示す。段差部で光が散乱し反射光量が低下して
いる。研磨を進めると、シリコンウェハ１の研磨面２０
は図６（ｂ）のようになり、金属膜２６の段差が小さく
なり、その時のイメージセンサ１７からの信号（図７
（ｂ））も段差が小さくなるため段差部での光の散乱が
小さくなり、反射光量の低下も小さくなる。さらに研磨
が進むと図６（ｃ）のように透明絶縁膜２７が露出す
る。金属膜２６に比べ、透明絶縁膜２７の反射率は小さ
いため、イメージセンサ１７からの信号（図７（ｃ））
は透明絶縁膜２７の部分で反射光量が低下する。そし
て、信号処理回路２４によってイメージセンサ１７の信
号を信号処理し研磨の終点を判断する。勿論、本実施形
態においても第１の実施形態と同様な手法によりシリコ
ン酸化膜等の終点検出を行うことが出来る。FIG. 6 is a cross-sectional view showing a change in the shape of the polishing surface 20 as the polishing progresses. Metal film 26 is formed on the surface of silicon wafer 1. The material of the metal film 26 is Al
Or Ti is used. The metal film 26 is polished to smooth the surface. FIG. 6A shows a state before the start of polishing. The signal from the image sensor 17 at that time is shown in FIG.
(A). Light is scattered at the step, and the amount of reflected light is reduced. As the polishing proceeds, the polished surface 20 of the silicon wafer 1
6B, the level difference of the metal film 26 is reduced, and the signal from the image sensor 17 at that time (FIG.
(B)) also has a small step, so that light scattering at the step portion is small, and a decrease in the amount of reflected light is also small. As the polishing proceeds further, the transparent insulating film 27 is exposed as shown in FIG. Since the reflectance of the transparent insulating film 27 is smaller than that of the metal film 26, the signal from the image sensor 17 (FIG. 7C)
The amount of reflected light at the transparent insulating film 27 decreases. Then, the signal of the image sensor 17 is processed by the signal processing circuit 24 to determine the end point of polishing. Of course, also in the present embodiment, the end point of the silicon oxide film or the like can be detected by the same method as in the first embodiment.
【００２２】そして、第１の実施の形態と同様に定盤３
および研磨布４に複数の貫通穴を設けて研磨量測定装置
を複数設け、シリコンウェハ内の異なる箇所での研磨の
状況を把握することにより、シリコンウェハ面内で研磨
速度にむらが発生した場合でも、終点の検出を正確に行
うことができる。図８は、本発明の第３の実施形態によ
る研磨量測定装置を示す概略構成図である。Then, similarly to the first embodiment, the surface plate 3
When a plurality of polishing holes are provided in the polishing cloth 4 and a plurality of polishing amount measuring devices are provided to grasp the polishing conditions at different locations in the silicon wafer, and the polishing speed becomes uneven in the silicon wafer surface. However, the end point can be accurately detected. FIG. 8 is a schematic configuration diagram showing a polishing amount measuring apparatus according to a third embodiment of the present invention.
【００２３】尚、第１、２の実施形態と同様の構成要素
については同じ符号を付けて説明を省略する。第１、２
の実施形態では被研磨面における散乱光の変化から研磨
面の終点検出を行っているのに対して、本実施形態では
被研磨面の微分干渉像を検出し、この像の変化から終点
検出を行っている。本実施形態では他の実施形態に比べ
てポラライザ（偏光子）３００、四分の一波長板３０
１、一波長板３０２、ノマルスキープリズム３０３、ア
ナライザ（偏光子）３０４を付加した点が異なる。光源
９から出た光束はノマルスキープリズム３０３により常
光線と異常光線の二光線に分けられる（図８では煩雑の
ため１光線のみ記す）。この常光線と異常光線の位相差
を変えることにより干渉色が変わりコントラストを変え
ることができる。図８の配置では位相差を変えるのにポ
ラライザ３００、四分の一波長板３０１、一波長板３０
２を用いる。ポラライザ３００を回転させることによ
り、位相差はλ／２〜３λ／２まで変化させることが出
来る。位相差はノマルスキープリズムを光軸と垂直な方
向に変位させることによっても可能である。The same components as those in the first and second embodiments are denoted by the same reference numerals, and description thereof is omitted. First, second
In the embodiment, the end point of the polished surface is detected from the change in the scattered light on the polished surface, whereas in the present embodiment, the differential interference image of the polished surface is detected, and the end point is detected from the change in the image. Is going. In this embodiment, a polarizer (polarizer) 300 and a quarter-wave plate 30 are different from the other embodiments.
1. The difference is that a one-wave plate 302, a Nomarski prism 303, and an analyzer (polarizer) 304 are added. The light beam emitted from the light source 9 is divided into two rays, an ordinary ray and an extraordinary ray, by the Nomarski prism 303 (only one ray is shown in FIG. 8 for simplicity). By changing the phase difference between the ordinary ray and the extraordinary ray, the interference color changes and the contrast can be changed. In the arrangement shown in FIG. 8, the polarizer 300, the quarter-wave plate 301, and the one-wave plate 30 are used to change the phase difference.
2 is used. By rotating the polarizer 300, the phase difference can be changed from λ / 2 to 3λ / 2. The phase difference can also be obtained by displacing the Nomarski prism in a direction perpendicular to the optical axis.
【００２４】このような構成は通常の微分干渉顕微鏡と
同様な構成を取ることができ、各種変形が可能である。
このようにして微分干渉像を好ましいコントラストで検
出することができる。このような微分干渉像は被研磨面
の段差部で強度が大きく変化するため、終点検出に好適
となる。尚、終点検出の方法は第１、２の実施形態とほ
ぼ同様に行うことができ、光スポット内で光の強度変化
が無くなった時点で被研磨面が平坦になったことを検出
することができる。Such a configuration can have a configuration similar to that of a normal differential interference microscope, and various modifications are possible.
Thus, the differential interference image can be detected with a preferable contrast. Such a differential interference image has a great change in intensity at a step portion on the surface to be polished, and is therefore suitable for detecting an end point. The method of detecting the end point can be performed in substantially the same manner as in the first and second embodiments, and it is possible to detect that the surface to be polished has become flat when there is no change in light intensity within the light spot. it can.
【００２５】[0025]
【発明の効果】以上、説明したように本発明によれば所
定のスポット径を有する光スポットの像を観察すること
によって、被研磨面の終点検出を精度よく行うことが出
来る。また、被研磨面に形成される光スポットの焦点ず
れを検出し、この焦点ずれを補正することにより、研磨
に伴って被研磨面の位置がずれても精度よく終点検出を
行うことができる。As described above, according to the present invention, the end point of the surface to be polished can be accurately detected by observing the image of the light spot having a predetermined spot diameter. Further, by detecting the defocus of the light spot formed on the surface to be polished and correcting the defocus, it is possible to accurately detect the end point even if the position of the surface to be polished is deviated due to polishing.
【図１】本発明の第１の実施形態による研磨量測定装置
を備えたＣＭＰ装置を示す概略構成図である。FIG. 1 is a schematic configuration diagram illustrating a CMP apparatus including a polishing amount measuring apparatus according to a first embodiment of the present invention.
【図２】本発明の第１の実施形態による研磨量測定装置
を示す概略構成図である。FIG. 2 is a schematic configuration diagram showing a polishing amount measuring apparatus according to the first embodiment of the present invention.
【図３】本発明の第１の実施形態による研磨量測定装置
で研磨したシリコンウエハの研磨面の様子を示す断面図
である。FIG. 3 is a cross-sectional view showing a state of a polished surface of a silicon wafer polished by the polishing amount measuring device according to the first embodiment of the present invention.
【図４】本発明の第１の実施形態による研磨量測定装置
のイメージセンサの信号を示す図である。FIG. 4 is a diagram showing signals of an image sensor of the polishing amount measuring device according to the first embodiment of the present invention.
【図５】本発明の第２の実施形態による研磨量測定装置
を示す概略構成図である。FIG. 5 is a schematic configuration diagram showing a polishing amount measuring apparatus according to a second embodiment of the present invention.
【図６】本発明の第２の実施形態による研磨量測定装置
で研磨したシリコンウエハの研磨面の様子を示す断面図
である。FIG. 6 is a cross-sectional view showing a polished surface of a silicon wafer polished by a polishing amount measuring apparatus according to a second embodiment of the present invention.
【図７】本発明の第２の研磨量測定装置のイメージセン
サの信号を示す図である。FIG. 7 is a diagram showing signals of an image sensor of the second polishing amount measuring apparatus of the present invention.
【図８】本発明の第３の実施形態による研磨量測定装置
を示す概略構成図である。FIG. 8 is a schematic configuration diagram showing a polishing amount measuring apparatus according to a third embodiment of the present invention.
１・・・シリコンウェハ ２・・・バッキングパッド ３・・・定盤 ４・・・研磨布 ５・・・ウェハキャリア ８・・・研磨量測定装置 ９・・・光源 １０、１５・・・集光レンズ １１・・・視野絞り １２・・・コンデンサレンズ １３・・・ハーフミラー １４・・・対物レンズ １６・・・光路分割ハーフプリズム １７・・・イメージセンサ １８・・・焦点検出回路 １９・・・アクチュエータ ２０・・・研磨面 ２４・・・信号処理回路 ２５、２７・・・透明絶縁膜 ２６・・・金属膜 DESCRIPTION OF SYMBOLS 1 ... Silicon wafer 2 ... Backing pad 3 ... Surface plate 4 ... Polishing cloth 5 ... Wafer carrier 8 ... Polishing amount measuring apparatus 9 ... Light source 10, 15 ... Collection Optical lens 11 ... Field stop 12 ... Condenser lens 13 ... Half mirror 14 ... Objective lens 16 ... Optical path splitting half prism 17 ... Image sensor 18 ... Focus detection circuit 19 ... -Actuator 20-Polished surface 24-Signal processing circuit 25, 27-Transparent insulating film 26-Metal film
フロントページの続き (51)Int.Cl.6 識別記号 ＦＩ Ｇ０１Ｂ 11/00 Ｇ０１Ｂ 11/00 Ｆ 11/02 11/02 Ｇ 11/30 １０１ 11/30 １０１Ａ Continued on the front page (51) Int.Cl. 6 Identification symbol FI G01B 11/00 G01B 11/00 F 11/02 11/02 G 11/30 101 11/30 101A
Claims (7)
触させ、かつ相対運動させることによって、被研磨物を
研磨する装置に用いられる研磨量測定装置であって、 前記被研磨物の前記研磨布と接触する研磨面へ照明光を
供給し、所定のスポット径を有する光スポットを形成す
る照明光学系と、 対物レンズを含む観察光学系と、 前記観察光学系に関して前記研磨面とほぼ共役な面に配
置され前記光スポットが形成された領域の研磨面の変化
を検出する２次元センサと、 前記２次元センサから出力される前記研磨面の変化に応
じた信号の変化から前記研磨面が平坦になったことを検
出する平坦検出手段と、 を有することを特徴とする研磨量測定装置。1. A polishing amount measuring device used in an apparatus for polishing an object to be polished by bringing the object to be polished into contact with and relatively moving on a polishing cloth arranged on a surface plate, comprising: An illumination optical system that supplies illumination light to a polishing surface of the object that contacts the polishing cloth to form a light spot having a predetermined spot diameter; an observation optical system including an objective lens; and the polishing surface with respect to the observation optical system. A two-dimensional sensor arranged on a surface substantially conjugate with the surface and detecting a change in the polished surface in the region where the light spot is formed; and a change in a signal corresponding to the change in the polished surface output from the two-dimensional sensor. A polishing amount measuring device, comprising: flatness detecting means for detecting that a polished surface has become flat.
磨面で生じる散乱光を検出し、 前記平坦検出手段は、前記２次元センサによって検出さ
れる散乱光の変化から前記研磨面が平坦となったことを
検出することを特徴とする請求項１に記載の研磨量測定
装置。2. The two-dimensional sensor detects scattered light generated on the polished surface by the illumination light, and the flatness detecting means flattens the polished surface from a change in the scattered light detected by the two-dimensional sensor. The polishing amount measuring apparatus according to claim 1, wherein the polishing amount is detected.
干渉像を検出し、 前記平坦検出手段は、前記微分干渉像によって得られる
前記研磨面の位相の情報から前記研磨面が平坦となった
ことを検出することを特徴とする請求項１に記載の研磨
量測定装置。3. The two-dimensional sensor detects a differential interference image of the light spot, and the flatness detecting means determines that the polished surface has become flat based on phase information of the polished surface obtained from the differential interference image. The polishing amount measuring apparatus according to claim 1, wherein the polishing amount is detected.
出する焦点検出手段をさらに設けたことを特徴とする請
求項１、２、３に記載の研磨量測定装置。4. A polishing amount measuring apparatus according to claim 1, further comprising a focus detecting means for detecting a shift of a focus position by said observation optical system.
に基づいて、前記対物レンズを光軸方向に移動させる移
動手段をさらに設けたことを特徴とする請求項４に記載
の研磨量測定装置。5. A polishing amount measuring apparatus according to claim 4, further comprising a moving means for moving said objective lens in an optical axis direction based on a shift detected by said focus detecting means.
の後方所定の距離だけ離れた位置に配置されて、前記光
スポット像に応じた電気信号を出力する第１のイメージ
センサと、前記共役な面の前方所定の距離だけ離れた位
置に配置されて、前記光スポット像に応じた電気信号を
出力する第２のイメージセンサと、を有することを特徴
とする請求項４または５に記載の研磨量測定装置。6. A first image sensor, wherein said focus detection means is arranged at a position separated by a predetermined distance behind a surface conjugate with said polished surface, and outputs an electric signal according to said light spot image. 6. A second image sensor, which is disposed at a position separated by a predetermined distance in front of the conjugate plane and outputs an electric signal according to the light spot image. The polishing amount measuring device according to the above.
とも１つは前記２次元センサと共有であることを特徴と
する請求項６に記載の研磨量測定装置。7. The polishing amount measuring apparatus according to claim 6, wherein at least one of said first and second image sensors is shared with said two-dimensional sensor.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP9029342A JPH10229060A (en) | 1997-02-13 | 1997-02-13 | Polishing amount measuring equipment |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP9029342A JPH10229060A (en) | 1997-02-13 | 1997-02-13 | Polishing amount measuring equipment |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH10229060A true JPH10229060A (en) | 1998-08-25 |
Family
ID=12273570
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP9029342A Pending JPH10229060A (en) | 1997-02-13 | 1997-02-13 | Polishing amount measuring equipment |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH10229060A (en) |
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2008042220A (en) * | 2007-09-25 | 2008-02-21 | Ebara Corp | Method and apparatus for processing substrate |
| US7481945B2 (en) * | 2000-12-04 | 2009-01-27 | Nikon Corporation | Polishing progress monitoring method and device thereof, polishing device, semiconductor device production method, and semiconductor device |
| KR101188168B1 (en) * | 2005-10-25 | 2012-10-05 | 삼성디스플레이 주식회사 | System for manufacturing a flat panel type display and controlling method thereof |
| EP3909717A1 (en) | 2020-05-14 | 2021-11-17 | Ebara Corporation | Film thickness measurement apparatus, polishing apparatus, and film thickness measurement method |
| WO2022091532A1 (en) | 2020-11-02 | 2022-05-05 | 株式会社荏原製作所 | Polishing apparatus and polishing method |
-
1997
- 1997-02-13 JP JP9029342A patent/JPH10229060A/en active Pending
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7481945B2 (en) * | 2000-12-04 | 2009-01-27 | Nikon Corporation | Polishing progress monitoring method and device thereof, polishing device, semiconductor device production method, and semiconductor device |
| KR101188168B1 (en) * | 2005-10-25 | 2012-10-05 | 삼성디스플레이 주식회사 | System for manufacturing a flat panel type display and controlling method thereof |
| JP2008042220A (en) * | 2007-09-25 | 2008-02-21 | Ebara Corp | Method and apparatus for processing substrate |
| EP3909717A1 (en) | 2020-05-14 | 2021-11-17 | Ebara Corporation | Film thickness measurement apparatus, polishing apparatus, and film thickness measurement method |
| KR20210141369A (en) | 2020-05-14 | 2021-11-23 | 가부시키가이샤 에바라 세이사꾸쇼 | Film thickness measuring apparatus, polishing apparatus and film thickness measuring method |
| WO2022091532A1 (en) | 2020-11-02 | 2022-05-05 | 株式会社荏原製作所 | Polishing apparatus and polishing method |
| KR20230097048A (en) | 2020-11-02 | 2023-06-30 | 가부시키가이샤 에바라 세이사꾸쇼 | Polishing device and polishing method |
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