JP3875930B2 - Electron beam apparatus and device manufacturing method using the same - Google Patents

Description

ここで、Ｉo：カソード電流、ｅ：電荷、Γ：空間電荷制限条件によるショット雑音低減係数、Δｆ：増幅器の帯域幅、をそれぞれ意味する。
試料に流れるビーム電流をＩ_Pとすると、Ｉ_Pはカソード電流Ｉoより十分小さいので、分配雑音が加わる。即ち、試料でのショット雑音は、
【数２】

従って、試料電流に流れるショット雑音もΓ倍（Γ＜１）に低減されることが明らかとなった。
【０００９】
図４には、本発明の一つの実施形態による電子線装置１’が模式的に示されている。この電子線装置１’は、電子銃から放出された電子線を細く絞り、細く絞られた電子ビームを検査されるべき試料（例えばＣＭＰ装置で研磨されたウェハ等の試料）Ｗの表面上に照射する光学系（以下、単に光学系と呼ぶ）１０’と、ウェハＷから放出された二次電子を検出する検出系３０’と、ウェハＷを保持する試料台４０’とを備えている。
光学系１０’は、空間電荷制限条件で電子線を放出する図１の実施形態と同様の電子銃１１と、電子線を軸合わせする偏向器１２’及び１３’と，電子線を集束するレンズ１４’と，ＮＡ開口１５’と、偏向器１６’及び１７’と，電磁偏向器１７’’と、対物レンズ１８’とを備え、それらは、図４に示すように、ウェハＷの表面に垂直な方向に光軸Ａ’に沿って、電子銃１１を最上部にして順に配置されている。電子銃１１は、図１の実施形態と同様に熱電子放出型のカソード１１１、ウェーネルト１１２及びアノード１１３を有している。電子銃１１のウェーネルト１１２のバイアスをある程度深くすることにより、電子銃１１は空間電荷制限条件で動作することができ、カソードから放出される電流はショット雑音がΓ（但し、Γ＜１）倍に低減されている。また、７×１０⁶Ａ／ｃｍ²ｓｒの輝度が４．５ｋｖで得られ、ラングミュアの限界値４．２×１０⁵Ａ／ｃｍ²ｓｒより２桁以上大きい輝度が得られる。ＮＡ開口１５’は、ここから後方散乱された電子がカソード近傍のバーチャルカソードに戻る量を少なくするべく、レンズ１４’の試料側に設けられている。
検出系は、試料Ｗから放出された二次電子を検出する二次電子検出器３１’を有し、この二次電子検出器３１’は偏向器１６’よりも電子銃側に配置されている。
【００１０】
試料台４０’は、ウェハＷを平坦に固定する静電チャック４１’を有しており、この静電チャック４１’には複数個（本実施形態では３個）の穴４５（その内の一つのみを示す）が設けられている。これら穴には押し棒４６が挿入されている。ウェハＷを静電チャック４１’からアンロードする場合には、３本の押し棒４６でウェハを持ち上げ、アンロードアーム４７をウェハの下に入れ、アンロードアーム４７の上面に設けられた静電チャック４８で固定することにより行う。押し棒４６には弱いコイルバネ４９を介して小さい静電チャック５０が取り付けられており、ウェハＷのロード・アンロードが安全に行われる。ロード・アンロードチャンバ５１にはゲートバルブ５２を介して予備室５３が接続されている。アクチュエータ５４がアンロードアーム４７の駆動を行う。アンロードアーム４７、静電チャック４８及びアクチュエータ５４で搬送装置を構成する。また、静電チャック４１’はＸＹステージに固定されており、ＸＹステージは、Ｘ方向のステージ位置を測定するレーザスケール５５とセンサー５６、及びＹ方向のステージ位置を測定するレーザスケール５７を備えている。ＸＹステージは、更に、試料を一つの軸方向に連続的に移動させかつ他の軸方向にはステップ移動させる。
【００１１】
上記構成の電子線装置１’において、電子銃１１は空間電荷制限領域内で作動するように調整される。従って、電子線が発生させるショット雑音を大幅に小さくすることができる。電子銃１１から放出された電子線は、軸合わせ用の偏向器１２’及び１３’によりレンズ１４’とＮＡ開口１５’を最適に通過するように調整される。電子線は更にレンズ１４’と対物レンズ１８とで集束されてポイント状に細く絞られ、ウェハＷに合焦される。偏向器１６’及び１７’で電子ビームを偏向することによりウェハＷを走査する。この場合、上記のように、７×１０⁶Ａ／ｃｍ²ｓｒ以上の高い輝度が得られ、ラングミュアの限界値４．２×１０⁵Ａ／ｃｍ²ｓｒより１０倍以上大きいので、１００ｎｍの電子ビーム径で１００ｎＡ以上のビーム電流が得られる。従って、１００ＭＨｚで走査させてもＳ／Ｎ比２０が得られ、０．１μｍ以上の研磨面の傷等の欠陥を検出できる程の分解能が得られる。
ウェハＷから放出された二次電子は、電磁偏向器１７’’により光軸Ａから分離されて符号Ｂ’で示された軌道を通り、二次電子検出器３１’に入射して検出される。
【００１２】
次に、図５及び図６を参照して本発明による電子線装置を用いた半導体デバイスの製造方法を説明する。
図５は本発明による半導体デバイスの製造方法の一実施例を示すフローチャートである。この実施例の工程は以下の主工程を含んでいる。
（１）ウェハを製造するウェハ製造工程（又はウェハを準備するウェハ準備工程）
（２）露光に使用するマスクを製造するマスクを製造するマスク製造工程（又はマスクを準備するマスク準備工程）
（３）ウェハに必要な加工処理を行うウェハプロセッシング工程
（４）ウェハ上に形成されたチップを一個づつ切り出し、動作可能にならしめるチップ組立工程
（５）できたチップを検査するチップ検査工程
なお、上記のそれぞれの主工程は更に幾つかのサブ工程からなっている。
【００１３】
これらの主工程の中で、半導体デバイスの性能に決定的な影響を及ぼすのが（３）のウェハプロセッシング工程である。この工程では、設計された回路パターンをウェハ上に順次積層し、メモリーやＭＰＵとして動作するチップを多数形成する。このウェハプロセッシング工程は以下の各工程を含んでいる。
（１）絶縁層となる誘電体薄膜や配線部、或いは電極部を形成する金属薄膜等を形成する薄膜形成工程（ＣＶＤやスパッタリング等を用いる）
（２）この薄膜層やウェハ基板を酸化する酸化工程
（３）薄膜層やウェハ基板を選択的に加工するためにマスク（レチクル）を用いてレジストパターンを形成するリソグラフィー工程
（４）レジストパターンに従って薄膜層や基板を加工するエッチング工程（例えばドライエッチング技術を用いる）
（５）イオン・不純物注入拡散工程
（６）レジスト剥離工程
（７）加工されたウェハを検査する工程
なお、ウェハプロセッシング工程は必要な層数だけ繰り返し行い、設計通り動作する半導体デバイスを製造する。
【００１４】
図６は、図５のウェハプロセッシング工程の中核をなすリソグラフィー工程を示すフローチャートである。リソグラフィー工程は以下の各工程を含む。
（１）前段の工程で回路パターンが形成されたウェハ上にレジストをコートするレジスト塗布工程
（２）レジストを露光する工程
（３）露光されたレジストを現像してレジストのパターンを得る現像工程
（４）現像されたレジストパターンを安定化するためのアニール工程
上記の半導体デバイス製造工程、ウェハプロセッシング工程、及びリソグラフィー工程については、周知のものでありこれ以上の説明を要しないであろう。
上記（７）の検査工程に本発明に係る欠陥検査方法、欠陥検査装置を用いると、微細なパターンを有する半導体デバイスでも、スループット良く検査できるので、全数検査が可能となり、製品の歩留まりの向上、欠陥製品の出荷防止が可能となる。
【００１５】
【発明の効果】
本発明の電子線装置によれば、以下のような効果を奏する。
（１）ＬａＢ₆カソードを有する電子銃で７×１０⁶Ａ／ｃｍ²ｓｒ以上の高い輝度を得ることができ、ラングミュアの限界値４．２×１０⁵Ａ／ｃｍ²ｓｒより１０倍以上大きいので、１００ｎｍの電子ビーム径で１００ｎＡ以上のビーム電流が得られる。従って、１００ＭＨｚで走査させてもＳ／Ｎ比２０が得られ、０．１μｍ以上の研磨面の傷等の欠陥を検出できるようになった。
（２）熱電子放出電子銃を空間電荷制限条件で使用しかつ０．２程度のショット雑音低減係数Γが得られるので、銅メッキ層に存在するボイド等の欠陥を検出するような信号のコントラストが小さい場合でも、また１００ＭＨｚのような高い周波数で走査させても、十分なＳ／Ｎ比を得ることができるようになった。
（３）電子線を試料面と角度を持たせて入射させるため、銅の層を通る距離が少なく、Ｓ₂Ｏ₂の層を通って銅メッキの深部に到達させることによりエネルギー損失を少なくして電子ビームが銅メッキ層の底部に到達するため、底部のボイドを検出し易くなる。
【図面の簡単な説明】
【図１】本発明による、試料にメッキ層を形成した後直ちにその欠陥を検出することができる電子線装置の実施形態を模式的に示す図である。
【図２】（ａ）はウェハの断面の一部を示す図である。
（ｂ）はウェハの断面の位置に対応する二次電子信号波形を示す図である。
【図３】電子ビームをウェハ面に対して角度を持たせて入射させるようにした実施形態を示し、
（ａ）はウェハの断面の一部を示す図である。
（ｂ）はウェハの断面の位置に対応する二次電子信号波形を示す図である。
【図４】本発明による、ＣＭＰ装置で研磨されたウェハ等の試料表面の欠陥を検査する電子線装置の実施形態を模式的に示す図である。
【図５】デバイス製造工程を示すフローチャートである。
【図６】リソグラフィー工程を示すフローチャートである。
【符号の説明】
１、１’：電子線装置 １０、１０’：光学系
１１：電子銃 １２、１２’：偏向器
１３、１３’：偏向器 １４、１４’：レンズ
１６、１６’：偏向器 １７，１７’：偏向器
１８，１８’：対物レンズ ３１，３１’：検出器
４０、４０’：試料台 ４１，４１’：静電チャック
４２：マグネスケール ４６：押し棒
５１：ロード・アンロードチャンバ
５４：アクチュエータ ５５、５７：レーザスケール[0001]
[Industrial application fields]
The present invention relates to an electron beam apparatus and a device manufacturing method using the electron beam apparatus, and more specifically, for example, an electron beam apparatus that detects defects such as voids existing in a sample film on which a film such as copper plating is formed. By inspecting a sample surface polished by a polishing apparatus such as CMP, such as a scratch, at a high speed, and by inspecting a wafer or the like in the process using such an electron beam apparatus The present invention relates to a device manufacturing method capable of improving a yield rate.
[0002]
[Prior art]
For a sample (for example, a wafer) on which a film such as copper plating is formed, a defect such as a void may occur inside the copper plating layer. Conventionally, such defects inside the plated layer cannot be detected immediately after plating, and have been detected by performing potential contrast measurement after the wiring is completed. Moreover, the inspection of the sample surface after polishing with a CMP apparatus has been performed using an optical microscope.
On the other hand, when the electron gun is operating in the space charge limited region, it is known that the shot noise existing in the cathode current is multiplied by the shot noise reduction coefficient (Γ). Further, when the electron gun is an electron gun having a thermionic emission cathode, the brightness of the electron gun has a theoretical value called a Langmuir limit value, and it has been considered that this value cannot be greatly exceeded.
[0003]
[Problems to be solved by the invention]
As described above, conventionally, defects inside the plating layer cannot be detected immediately after plating, but can only be detected after polishing by a CMP apparatus. Has been detected. Therefore, it was impossible to immediately investigate the cause and take prompt measures. Further, when the sample surface after being polished by the CMP apparatus is inspected by an optical microscope, it is difficult to find a defect having a size of 0.3 μm or less.
Furthermore, it is unclear whether the shot noise existing in the sample current can be reduced even if the shot noise existing in the cathode current is reduced by operating the electron gun in the space charge limited region. Further, when the electron gun is an electron gun having a thermionic emission cathode, there is a Langmuir limit value for the brightness of the electron gun. No one thought that high brightness could be achieved.
The present invention has been made in view of the conventional problems as described above, and one problem to be solved is to provide an electron beam apparatus capable of detecting defects immediately after forming a plating layer on a sample. It is to be.
Another problem to be solved by the present invention is to provide an electron beam apparatus capable of inspecting defects such as scratches on a flat surface of a sample immediately after being polished by a CMP apparatus at a high speed with a resolution of 0.2 μm or less. That is.
Still another problem to be solved by the present invention is to provide an electron beam apparatus capable of reducing shot noise by Γ times even when only an electron beam current of about 1/100 to 1/10000 of the cathode current can be obtained. Is to provide.
Another problem to be solved by the present invention is a thermionic emission electron gun (LaB ₆ electron gun), which is comparable to a field emission (FE) electron gun, a thermal field emission (TFE) electron gun, and a Schottky electron gun. It is providing the electron beam apparatus which has the brightness | luminance of.
Still another problem to be solved by the present invention is to provide an electron gun provided with the electron gun as described above, and a device manufacturing method for inspecting a sample defect during the process using the electron beam apparatus Is to provide.
[0004]
[Means for Solving the Problems]
The above problem is solved by the following means. That is, one of the inventions of the electron beam apparatus of the present application is to narrow the electron beam emitted from the electron gun, scan the film-formed sample, and detect reflected electrons or secondary electrons emitted from the scanning point. An electron beam apparatus for detecting defects existing inside the sample film, wherein the incident energy of the electron beam to the sample has a range of 2.5 times or more the thickness of the sample film Has been.
Another invention of the present application is that the electron beam emitted from the electron gun is narrowed down, the surface of the sample after being polished by the CMP apparatus is scanned, and secondary electrons emitted from the scanning point are detected to polish the sample. An electron beam apparatus for detecting surface defects, wherein the scanning clock frequency is 100 MHz or more.
In one embodiment of the present invention, an electrostatic chuck that holds a sample, a stage that continuously moves the sample in one axial direction and a step movement in the other axial direction, and measures the amount of movement of the stage The apparatus further includes a laser scale or magnescale for carrying out, a transfer device with an electrostatic chuck for loading and unloading a sample, a push rod with an electrostatic chuck for pushing up the sample, and a load / unload chamber. In another embodiment of the present invention, the electron gun is set to operate in the space charge limited region and the shot noise reduction coefficient of the electron beam incident on the sample is set to 1 or less, or the brightness of the electron gun is Langmuir It is configured to have a luminance of 10 times or more of the limit.
In another invention of the present application, a sample in the middle of a process is evaluated using the electron beam apparatus as described above.
[0005]
DETAILED DESCRIPTION OF THE INVENTION
An electron beam apparatus capable of detecting a defect immediately after forming a plating layer on a sample according to the present invention will be described with reference to the drawings.
In FIG. 1, an electron beam apparatus 1 according to an embodiment of the present invention is schematically shown. This electron beam apparatus 1 narrows down an electron beam emitted from an electron gun and irradiates the surface of a sample W (for example, a wafer on which a copper plating film is formed) W to be inspected with a finely focused electron beam. An optical system (hereinafter simply referred to as an optical system) 10, a detection system for detecting reflected electrons or secondary electrons emitted from the wafer W, and a sample stage 40 for holding the wafer W.
The optical system 10 includes an electron gun 11 that emits an electron beam under space charge limiting conditions, deflectors 12 and 13 that align the electron beam, a lens 14 that focuses the electron beam, an NA aperture 15, and a deflector 16. 1 and 17 and an objective lens 18, which are arranged in order along the optical axis A in the direction perpendicular to the surface of the wafer W with the electron gun 11 at the top, as shown in FIG. . The electron gun 11 has a thermionic emission type cathode (LaB ₆ cathode) 111, Wehnelt 112 and anode 113. The cathode 111 is formed in a conical shape whose tip is a part of a sphere having a curvature radius of 30 μm, and the cone angle of this conical shape is 90 degrees. The electron gun 11 is operated under a space charge limited condition, and the shot noise of the current emitted from the cathode is reduced by Γ (where Γ <1) times. A luminance of 7.5 × 10 ⁸ A / cm ² sr is obtained at 20 kv at a cathode current of 980 μA.
The detection system includes a reflected electron detector 31 that detects reflected electrons emitted from the sample W, and a secondary electron detector 32 that detects secondary electrons emitted from the sample W. The sample stage 40 has an electrostatic chuck 41 for fixing a wafer. The electrostatic chuck 41 is provided with electrodes divided into two portions, a central portion and a peripheral portion, on which a wafer W is mounted. Is fixed flat. Even a wafer that is warped upward can be chucked flat. The electrostatic chuck is fixed to an XY stage. The XY stage includes a magnescale 42 and a sensor 43 that measure a position in the X direction, and a sensor 44 that measures a position in the Y direction. The XY stage further moves the sample continuously in one axial direction and steps in the other axial direction.
[0006]
In the electron beam apparatus 1 configured as described above, the electron beam emitted from the electron gun 11 creates an imaginary crossover behind the cathode 11. In this case, by setting the crossover to an imaginary crossover, it is possible to achieve ultra-high luminance far exceeding the limit value of Langmuir in a relatively wide range. A voltage to be applied to the Wehnelt 112 is determined so that an electron gun current capable of obtaining ultra-high brightness flows. The crossover passes through the deflectors 12 and 13 for axial alignment and the NA aperture 15, is focused by the lens 14 and the objective lens 18, is narrowed into a beam shape, is converged on the wafer W, and is reduced on the sample. Form an image. The wafer W can be scanned by deflecting the electron beam by the deflectors 16 and 17. In this case, the scanning clock frequency can be 100 MHz or more.
The secondary electrons emitted from the wafer W are separated from the optical axis A by the electric field of the detector 32 provided under the objective lens, and enter the secondary electron detector 32 through the trajectory indicated by B. Is detected.
[0007]
FIG. 2 shows a secondary electron signal waveform of a wafer as a sample obtained by the electron beam apparatus according to the present invention. FIG. 2 (a) shows a part of the cross section of the wafer, and FIG. The secondary electron signal waveform corresponding to the position of the cross section is shown. In FIG. 2A, reference numeral 60 is a copper plating layer, 61 is a defect such as a void formed in the copper plating layer, and 62 is a SiO ₂ layer. At the position where there is no defect with respect to the incidence of the electron beam 63, the signal waveform of the reflected electrons 64 is large as indicated by reference numerals 65 and 67 (FIG. 2B), while at the position where the defect exists, The signal waveform of the reflected electrons 64 is small as indicated by reference numeral 66 (FIG. 2B). In order for the reflected electrons 64 to emerge from the surface, it is necessary that the energy of the incident electron beam 63 enters a place where there is a defect, where it is backscattered and the electrons exit to the surface. Accordingly, the range (range) of the electron beam needs to be twice the thickness of the copper plating layer or film, and may be 2.5 times the range in consideration of some margin. On the other hand, secondary electrons 68 that are created immediately before the reflected electrons are emitted to the surface are detected by being emitted to the surface. In the present embodiment, since the thickness of the copper plating layer is 1 μm, the energy of the electron beam is 30 kev.
FIG. 3 shows an embodiment which is particularly effective when detecting voids existing in the deep part of the groove of the copper plating layer. 3A shows a part of the cross section of the wafer, and FIG. 3B shows a secondary electron signal waveform corresponding to the position of the cross section. In this embodiment, the electron beam 63 is incident from a direction that is not perpendicular to the surface of the wafer but has an angle, and is allowed to pass through the SiO ₂ layer 62 so that the energy beam is reduced and the electron beam is plated with copper. Try to reach the bottom of the layer. In the case of this embodiment, at the position where the void 61 is present, the signal waveform of the reflected electrons 64 is indicated by reference numeral 66 (FIG. 3B), and the signal waveforms 65 and 67 at the position where there is no void, It is greatly distorted.
[0008]
Next, an electron beam apparatus for inspecting defects on the surface of a sample such as a wafer polished by a CMP apparatus according to the present invention will be described with reference to FIG.
First, it will be examined how the shot noise of the electron beam emitted from the cathode becomes distribution noise when the beam current flowing through the sample is very small. The cathode shall operate under space charge limited conditions.
Shot noise in the electron beam emitted from the cathode is
[Expression 1]

Here, Io: cathode current, e: charge, Γ: shot noise reduction coefficient due to space charge limiting conditions, and Δf: amplifier bandwidth, respectively.
Assuming that the beam current flowing through the sample is I _P , I _P is sufficiently smaller than the cathode current Io, so that distributed noise is added. That is, shot noise at the sample is
[Expression 2]

Therefore, it has been clarified that the shot noise flowing in the sample current is also reduced by Γ times (Γ <1).
[0009]
FIG. 4 schematically shows an electron beam apparatus 1 ′ according to one embodiment of the present invention. This electron beam apparatus 1 'narrows down the electron beam emitted from the electron gun, and on the surface of a sample W to be inspected (for example, a sample such as a wafer polished by a CMP apparatus) W. An irradiating optical system (hereinafter simply referred to as an optical system) 10 ′, a detection system 30 ′ for detecting secondary electrons emitted from the wafer W, and a sample stage 40 ′ for holding the wafer W are provided.
The optical system 10 ′ includes an electron gun 11 similar to the embodiment of FIG. 1 that emits an electron beam under space charge limiting conditions, deflectors 12 ′ and 13 ′ that align the electron beam, and a lens that focuses the electron beam. 14 ′, NA aperture 15 ′, deflectors 16 ′ and 17 ′, electromagnetic deflector 17 ″, and objective lens 18 ′, which are formed on the surface of wafer W as shown in FIG. They are arranged in order along the optical axis A ′ in the vertical direction with the electron gun 11 at the top. The electron gun 11 has a thermionic emission type cathode 111, a Wehnelt 112, and an anode 113 as in the embodiment of FIG. By increasing the bias of the Wehnelt 112 of the electron gun 11 to some extent, the electron gun 11 can operate under a space charge limited condition, and the current emitted from the cathode is shot noise is Γ (where Γ <1) times. Has been reduced. Also, a luminance of 7 × 10 ⁶ A / cm ² sr is obtained at 4.5 kv, and a luminance two or more orders of magnitude greater than the Langmuir limit value of 4.2 × 10 ⁵ A / cm ² sr is obtained. The NA aperture 15 'is provided on the sample side of the lens 14' so as to reduce the amount of backscattered electrons returning from here to the virtual cathode near the cathode.
The detection system includes a secondary electron detector 31 ′ that detects secondary electrons emitted from the sample W, and the secondary electron detector 31 ′ is disposed closer to the electron gun than the deflector 16 ′. .
[0010]
The sample stage 40 ′ has an electrostatic chuck 41 ′ for fixing the wafer W flat. The electrostatic chuck 41 ′ has a plurality of (three in this embodiment) holes 45 (one of them). Only one is shown). Push rods 46 are inserted into these holes. When unloading the wafer W from the electrostatic chuck 41 ′, the wafer is lifted by the three push rods 46, the unload arm 47 is placed under the wafer, and the electrostatic provided on the upper surface of the unload arm 47. This is performed by fixing with the chuck 48. A small electrostatic chuck 50 is attached to the push rod 46 via a weak coil spring 49, so that the wafer W can be safely loaded and unloaded. A spare chamber 53 is connected to the load / unload chamber 51 via a gate valve 52. The actuator 54 drives the unload arm 47. The unload arm 47, the electrostatic chuck 48, and the actuator 54 constitute a transfer device. The electrostatic chuck 41 ′ is fixed to an XY stage, and the XY stage includes a laser scale 55 and a sensor 56 for measuring the stage position in the X direction, and a laser scale 57 for measuring the stage position in the Y direction. Yes. The XY stage further moves the sample continuously in one axial direction and steps in the other axial direction.
[0011]
In the electron beam apparatus 1 ′ having the above configuration, the electron gun 11 is adjusted so as to operate in the space charge limited region. Therefore, the shot noise generated by the electron beam can be greatly reduced. The electron beam emitted from the electron gun 11 is adjusted so as to optimally pass through the lens 14 ′ and the NA aperture 15 ′ by the deflectors 12 ′ and 13 ′ for axial alignment. The electron beam is further focused by the lens 14 ′ and the objective lens 18, narrowed into a point shape, and focused on the wafer W. The wafer W is scanned by deflecting the electron beam by the deflectors 16 ′ and 17 ′. In this case, as described above, a high luminance of 7 × 10 ⁶ A / cm ² sr or more is obtained, which is 10 times or more larger than the Langmuir limit value of 4.2 × 10 ⁵ A / cm ² sr. A beam current of 100 nA or more can be obtained with a beam diameter. Therefore, an S / N ratio of 20 is obtained even when scanning is performed at 100 MHz, and a resolution that can detect defects such as scratches on a polished surface of 0.1 μm or more is obtained.
The secondary electrons emitted from the wafer W are separated from the optical axis A by the electromagnetic deflector 17 ″, pass through the trajectory indicated by the symbol B ′, and enter the secondary electron detector 31 ′ to be detected. .
[0012]
Next, a semiconductor device manufacturing method using the electron beam apparatus according to the present invention will be described with reference to FIGS.
FIG. 5 is a flowchart showing an embodiment of a method of manufacturing a semiconductor device according to the present invention. The process of this embodiment includes the following main processes.
(1) Wafer manufacturing process for manufacturing a wafer (or wafer preparation process for preparing a wafer)
(2) Mask manufacturing process for manufacturing a mask for manufacturing a mask used for exposure (or mask preparation process for preparing a mask)
(3) Wafer processing step for performing necessary processing on the wafer (4) Chip assembly step for cutting out the chips formed on the wafer one by one and making them operable (5) Chip inspection step for inspecting the completed chips Each of the above main processes is further composed of several sub-processes.
[0013]
Among these main processes, the wafer processing process (3) has a decisive influence on the performance of the semiconductor device. In this process, designed circuit patterns are sequentially stacked on a wafer to form a large number of chips that operate as memories and MPUs. This wafer processing step includes the following steps.
(1) A thin film forming process for forming a dielectric thin film to be an insulating layer, a wiring part, or a metal thin film for forming an electrode part (using CVD, sputtering, etc.)
(2) Oxidation step for oxidizing the thin film layer and wafer substrate (3) Lithography step for forming a resist pattern using a mask (reticle) to selectively process the thin film layer and wafer substrate (4) According to the resist pattern Etching process for processing thin film layers and substrates (eg using dry etching technology)
(5) Ion / impurity implantation / diffusion process (6) Resist stripping process (7) Process for inspecting the processed wafer The wafer processing process is repeated for the required number of layers to manufacture a semiconductor device that operates as designed.
[0014]
FIG. 6 is a flowchart showing a lithography process which is the core of the wafer processing process of FIG. The lithography process includes the following processes.
(1) Resist coating step for coating a resist on the wafer on which the circuit pattern is formed in the previous step (2) Step for exposing the resist (3) Development step for developing the exposed resist to obtain a resist pattern ( 4) Annealing process for stabilizing the developed resist pattern The semiconductor device manufacturing process, the wafer processing process, and the lithography process are well known and need no further explanation.
When the defect inspection method and the defect inspection apparatus according to the present invention are used in the inspection process of (7) above, even a semiconductor device having a fine pattern can be inspected with high throughput, so that 100% inspection can be performed and the yield of products can be improved. It is possible to prevent shipment of defective products.
[0015]
【The invention's effect】
The electron beam apparatus of the present invention has the following effects.
(1) An electron gun having a LaB ₆ cathode can obtain a high brightness of 7 × 10 ⁶ A / cm ² sr or more, and is 10 times or more larger than the Langmuir limit value of 4.2 × 10 ⁵ A / cm ² sr. Therefore, a beam current of 100 nA or more can be obtained with an electron beam diameter of 100 nm. Therefore, an S / N ratio of 20 was obtained even when scanning at 100 MHz, and defects such as scratches on the polished surface of 0.1 μm or more could be detected.
(2) Since a thermionic emission electron gun is used under space charge limiting conditions and a shot noise reduction coefficient Γ of about 0.2 is obtained, signal contrast that detects defects such as voids existing in the copper plating layer A sufficient S / N ratio can be obtained even when the frequency is small or when scanning is performed at a high frequency such as 100 MHz.
(3) Since the electron beam is incident at an angle with respect to the sample surface, the distance through the copper layer is small, and energy loss is reduced by reaching the deep part of the copper plating through the S ₂ O ₂ layer. Since the electron beam reaches the bottom of the copper plating layer, it becomes easy to detect the void at the bottom.
[Brief description of the drawings]
FIG. 1 is a diagram schematically showing an embodiment of an electron beam apparatus capable of detecting defects immediately after forming a plating layer on a sample according to the present invention.
FIG. 2A is a diagram showing a part of a cross section of a wafer.
(B) is a figure which shows the secondary electron signal waveform corresponding to the position of the cross section of a wafer.
FIG. 3 shows an embodiment in which an electron beam is incident on the wafer surface at an angle;
(A) is a figure which shows a part of cross section of a wafer.
(B) is a figure which shows the secondary electron signal waveform corresponding to the position of the cross section of a wafer.
FIG. 4 is a diagram schematically showing an embodiment of an electron beam apparatus for inspecting defects on the surface of a sample such as a wafer polished by a CMP apparatus according to the present invention.
FIG. 5 is a flowchart showing a device manufacturing process.
FIG. 6 is a flowchart showing a lithography process.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1, 1 ': Electron beam apparatus 10, 10': Optical system 11: Electron gun 12, 12 ': Deflector 13, 13': Deflector 14, 14 ': Lens 16, 16': Deflector 17, 17 ' : Deflectors 18, 18 ': Objective lenses 31, 31': Detectors 40, 40 ': Sample stage 41, 41': Electrostatic chuck 42: Magnescale 46: Push rod 51: Load / unload chamber 54: Actuator 55, 57: Laser scale

Claims (3)

A sample in which a copper plating layer is formed on a SiO ₂ layer provided with a groove is scanned with a finely focused electron beam emitted from an electron gun, and a reflected electron or secondary electron emitted from the scanning point is detected and the sample is detected. An electron beam apparatus for detecting defects existing in the film of
The electron beam apparatus has a deflector for deflecting an electron beam, and the deflector has an angle at which the electron beam is incident on the sample, passes through the SiO ₂ layer of the sample, and the groove portion of the SiO ₂ layer An electron beam apparatus, wherein an electron beam is incident on a copper plating layer at the bottom of the electron beam. 2. The electron beam apparatus according to claim 1 , wherein an electrostatic chuck that holds the sample, a stage that continuously moves the sample in one axial direction, and a step movement in the other axial direction, and an amount of movement of the stage The apparatus further comprises a laser scale or a magnescale for measuring the load, a transfer device with an electrostatic chuck for loading / unloading the sample, a push rod with an electrostatic chuck for pushing up the sample, and a load / unload chamber. An electron beam apparatus. And performing an assessment of in-process wafer using an electron beam apparatus according to claim 1 or 2, a device manufacturing method.

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