JP4029975B2

JP4029975B2 - Measuring method of shoulder arc radius of notch of semiconductor wafer

Info

Publication number: JP4029975B2
Application number: JP2002367278A
Authority: JP
Inventors: 啓介山崎
Original assignee: Covalent Materials Corp
Current assignee: Coorstek KK
Priority date: 2002-12-18
Filing date: 2002-12-18
Publication date: 2008-01-09
Anticipated expiration: 2022-12-18
Also published as: JP2004198264A

Description

【０００１】
【発明の属する技術分野】
本発明はウェーハノッチの肩円弧部半径の測定方法に係わり、特にノッチ肩円弧部の始点、終点を正確に検出し、円弧部半径の測定を行なうために検出アルゴリズムを用いるウェーハノッチの肩円弧部半径の測定方法に関する。
【０００２】
【従来の技術】
半導体ウェーハにおける結晶方向の判別及び位置決めを容易にするために、半導体ウェーハの外周の一部にいわゆるオリフラに代えてノッチを設けることが主流となっている。
【０００３】
このノッチ部分における各部の寸法は、ＳＥＭＩ（Semiconductor Equipments and Materials International）規格により定められており、その規格により定められている各寸法は、幅、深さ、角度、先端円弧部、面取り幅などである。
【０００４】
従来、図７に示すように、画像処理を用いたノッチ形状測定方法により、幅、深さ、角度先端円弧部の各寸法測定を行なっており、ノッチ先端円弧部寸法測定方法としては、画像データより得られるノッチ先端円弧部の最深部座標並びに左右にそれぞれ微小量振った座標（例えば±０．５ｍｍ）の３点座標より円弧部の寸法を求めている。
【０００５】
近年、半導体デバイスの超微細化に伴ない、電子回路の焼付け時等により正確な位置決めが必要となり、このため、ノッチ肩円弧部寸法（半径）の測定も必要になっている。
【０００６】
しかしながら、従来、ノッチ肩円弧部半径の測定は、行われておらず、また、従来の３点の座標を取る方法を用いて、ノッチ肩円弧部の半径を求めることが可能であるが、画像取込み時のウェーハのズレ、傾き等を考慮すると、ウェーハ外周部のノッチ肩円弧部始点からノッチＶ部までのノッチ肩円弧部終点を通る正確な円弧部半径を求めることが困難であり、精度良くノッチの肩円弧部半径を測定できない。
【０００７】
なお、従来のウェーハノッチ寸法測定装置として、投光部と受光部とを回転されるウェーハの周縁形状を読み取るように配置し、ウェーハの周縁形状に応じたウェーハ周縁検出信号を出力するウェーハ周縁検出手段と、回転するウェーハの回転角位置を検出し、ウェーハ回転角位置検出信号を出力するウェーハ回転角位置検出手段と、ウェーハ周縁検出信号とウェーハ回転角位置検出信号とからノッチ寸法を演算する演算手段を有する測定装置がある（特許文献１）。しかしながら、特許文献１に記載の測定装置を用いたノッチ寸法測定方法は、ノッチ角度の測定であり、ノッチの肩円弧部半径を精度良く測定するものではない。
【０００８】
また、半導体ウェーハのノッチ部分の一面をテレビカメラにより撮像するように構成され、半導体ウェーハの他面側からノッチ部分に光を照射する第１照明灯、ウェーハの面取り面を避けてウェーハ表面に対して光を照射する第２照明灯、ウェーハの面取り面とウェーハ表面に対して光を照射する第３照明灯が設けられ、照明制御装置により各照明灯の点灯の組み合わせを変えつつ、テレビカメラにより半導体ウェーハのノッチ部分を撮像することで、ノッチ部分の形状測定、面取り幅の測定、及びノッチ部分のキズの有無の観察が実行されるウェーハの形状認識装置がある（特許文献２）。しかしながら、特許文献２に記載の測定装置を用いたノッチ寸法測定方法は、ノッチの幅、深さ、面取り幅を測定するものであり、肩円弧部半径を精度良く測定するものではなく、さらに、この装置を用いても、上記のように画像取込み時のウェーハのズレ、傾き等を考慮すると、ウェーハ外周部のノッチ肩円弧部始点からノッチＶ部までのノッチ肩円弧部終点を通る正確な円弧部半径を求めることが困難であり、精度良くノッチの肩円弧部半径を測定できない。
【０００９】
【特許文献１】
特開平７−２６０４３２号公報（段落番号［０００９］、［００１９］、図１）
【００１０】
【特許文献２】
特開平１０−３８５３９号公報（段落番号［００２２］〜［００２６］、図１）
【００１１】
【発明が解決しようとする課題】
本発明は上述した事情を考慮してなされたもので、精度良くノッチの肩円弧部半径を測定できるウェーハノッチの肩円弧部半径の測定方法を提供することを目的とする。
【００１２】
【課題を解決するための手段】
上記目的を達成するため、本発明の１つの態様によれば、半導体ウェーハの画像処理されたノッチ部輪郭データからノッチ肩円弧部を抽出し、ノッチ肩円弧部の始点、終点を検出し、円弧部半径を求める半導体ウェーハのノッチの肩円弧部半径の測定方法であって、ノッチＶ部の接点であるノッチ肩円弧部の終点を求めるのに最大値とノッチ底部の２点の座標から得られる２点を通る線分の式ｙ＝ａ１ｘ＋ｂ１と、最大値からノッチ底部までの各座標データの最小二乗法で求められる近似直線式ｙ＝ａ２ｘ＋ｂ２を、座標をずらしながら比較し、差が最小となる傾き線を求めて円弧部半径を求めることを特徴とする半導体ウェーハのノッチの肩円弧部半径の測定方法が提供される。これにより、精度良くかつ容易に肩円弧部半径を測定できるウェーハノッチの肩円弧部半径の測定方法が実現される。
【００１４】
【発明の実施の形態】
以下、本発明に係わる半導体ウェーハのノッチの肩円弧部半径の測定方法の実施形態について説明する。
【００１５】
本発明に係わる半導体ウェーハのノッチの肩円弧部半径の測定方法は、半導体ウェーハの画像処理されたノッチ部輪郭データからノッチ肩円弧部を抽出し、ノッチ肩円弧部の始点、終点をアルゴリズムを用いて検出し、円弧部半径を求める。
【００１６】
次に、本発明に係わる半導体ウェーハのノッチの肩円弧部半径の測定方法を、図１に示す測定方法を実行するためのフローチャートに沿って説明する。
【００１７】
図２に示すように、画像処理装置により取り込んだノッチ部画像より、ノッチ近傍輪郭画像座標データを抽出し、このノッチ近傍輪郭画像座標データを用いて、図３に示すように、最小値座標（Ｘｍ、Ｙｍ）を検出する（Ｓ１）。
これは、図３に示すように、Ｘ軸方向に検索して、Ｙが最小になるノッチ底部すなわち最小値座標（Ｘｍ、Ｙｍ）として検出する。
【００１８】
左側最大値座標（Ｘｌ_１、Ｙｌ_１）及び右側最大値座標（Ｘｒ_２、Ｙｒ_２）を検出する（Ｓ２）。
これは、図３に示すように、ノッチ底部よりＸをプラス、マイナスそれぞれの方向に検索し、Ｙが最大となる左側最大値座標（Ｘｌ_１、Ｙｌ_１）及び右側最大値座標（Ｘｒ_１、Ｙｒ_１）を検出する。
【００１９】
Ｓ２において得られた左側最大値座標（Ｘｌ_１、Ｙｌ_１）及び右側最大値座標（Ｘｒ_１、Ｙｒ_１）を結ぶ線分として、ノッチ接線Ｌｔの方程式を求める（Ｓ３）。
図４に示すように、左右傾き線Ｌｌ、Ｌｒの方程式を算出する（Ｓ４）。
【００２０】
左側最大値とノッチ底部の２点の座標から得られる２点を通る線分の式ｙ＝ａ_１ｘ＋ｂ_１を求める。次に左側最大値からノッチ底部までの各座標データの近似直線式ｙ＝ａ_２ｘ＋ｂ_２を最小二乗法で求める。左側最大値座標側データから一つプラス側とノッチ底部データから一つマイナス側と順次区間を狭めながら同様に傾き線分の式を求めａ_１とａ_２、ｂ_１とｂ_２を比較し、この差が小さくなる区間を見つけ、この２点を通る線分を左傾き線Ｌｌとする。右傾き線Ｌｒも同様に求める。
【００２１】
図５に示すように、左右円弧部の開始点座標、終了点座標を検出し、円弧部を抽出する（Ｓ５）。
輪郭座標データ線分とノッチ接線及び傾き線が交わる２点の座標を円弧部の開始・終了位置座標とし、円弧部を抽出する。これにより、ノッチ肩円弧部始点と終点の位置が正確に算出できて、始点から終点を通る正確な円弧部半径を求めることができる。
【００２２】
図６に示すように、左右円弧部中間点▲３▼を検出する（Ｓ６）。
ノッチ接線との交点▲１▼と傾き線接線との交点▲２▼を結ぶ直線の垂直２等分線と円弧部が交わる座標を点▲３▼とし３点円弧部の半径を求める（Ｓ７）。
【００２３】
上記のように本発明に係わる半導体ウェーハのノッチの肩円弧部半径の測定方法によれば、画像取込み時のウェーハのズレ、傾き等を考慮する必要がなく、ウェーハ外周部のノッチ肩円弧部始点からノッチＶ部までのノッチ肩円弧部終点を通る正確な円弧部半径を精度良くかつ容易に測定できる。
【００２４】
【発明の効果】
本発明に係わる半導体ウェーハのノッチの肩円弧部半径の測定方法によれば、精度良くかつ容易に肩円弧部半径を測定できるウェーハノッチの肩円弧部半径の測定方法を提供することができる。
【図面の簡単な説明】
【図１】本発明に係わる半導体ウェーハのノッチの肩円弧部半径の測定方法を実行するためのフローチャート。
【図２】本発明に係わる半導体ウェーハのノッチの肩円弧部半径の測定方法に用いられるノッチ近傍輪郭画像座標データ図。
【図３】本発明に係わる半導体ウェーハのノッチの肩円弧部半径の測定方法に用いられるノッチ接線の算出図。
【図４】本発明に係わる半導体ウェーハのノッチの肩円弧部半径の測定方法に用いられる傾き線算出図。
【図５】本発明に係わる半導体ウェーハのノッチの肩円弧部半径の測定方法に用いられる円弧抽出図。
【図６】本発明に係わる半導体ウェーハのノッチの肩円弧部半径の測定方法に用いられる円弧部中間点検出図。
【図７】従来の半導体ウェーハのノッチ先端円弧部半径の測定方法。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for measuring a shoulder arc radius of a wafer notch, and more particularly, to detect the start point and end point of a notch shoulder arc accurately and to use the detection algorithm to measure the arc radius. The present invention relates to a method for measuring a radius.
[0002]
[Prior art]
In order to facilitate the determination and positioning of the crystal direction in a semiconductor wafer, it is the mainstream to provide a notch in place of a so-called orientation flat on a part of the outer periphery of the semiconductor wafer.
[0003]
The dimensions of each part in this notch are determined by SEMI (Semiconductor Equipment and Materials International) standards, and the dimensions determined by the standards are the width, depth, angle, tip arc, chamfer width, etc. is there.
[0004]
Conventionally, as shown in FIG. 7, the width, depth, and angle tip arc part dimensions are measured by a notch shape measurement method using image processing, and the notch tip arc part dimension measurement method includes image data. The dimension of the arc portion is obtained from the deepest portion coordinates of the arc portion of the notch tip obtained and the three-point coordinates of a minute amount (for example, ± 0.5 mm) that is shifted to the left and right.
[0005]
In recent years, with the miniaturization of semiconductor devices, accurate positioning is required during printing of electronic circuits and the like, and therefore measurement of the notch shoulder arc dimension (radius) is also required.
[0006]
However, conventionally, the measurement of the radius of the notch shoulder arc portion has not been performed, and it is possible to obtain the radius of the notch shoulder arc portion using the conventional method of taking the coordinates of three points. Taking into account the wafer misalignment, tilt, etc. during loading, it is difficult to obtain an accurate arc radius that passes through the notch shoulder arc end point from the notch shoulder arc start point to the notch V portion on the outer periphery of the wafer with high accuracy. The radius of the shoulder arc of the notch cannot be measured.
[0007]
As a conventional wafer notch dimension measuring device, a light emitting part and a light receiving part are arranged so as to read the peripheral shape of the rotated wafer, and a wafer peripheral detection signal is output according to the peripheral shape of the wafer. Means for detecting the rotation angle position of the rotating wafer and outputting a wafer rotation angle position detection signal, and calculating the notch dimension from the wafer peripheral detection signal and the wafer rotation angle position detection signal. There is a measuring device having means (Patent Document 1). However, the notch dimension measuring method using the measuring device described in Patent Document 1 is a notch angle measurement, and does not accurately measure the shoulder arc radius of the notch.
[0008]
Moreover, it is comprised so that one surface of the notch part of a semiconductor wafer may be imaged with a television camera, the 1st illuminating lamp which irradiates light to the notch part from the other surface side of a semiconductor wafer, and avoids the chamfering surface of a wafer, and a wafer surface A second illumination lamp for irradiating light, and a third illumination lamp for irradiating light to the chamfered surface of the wafer and the wafer surface. There is a wafer shape recognition device in which a notch portion of a semiconductor wafer is imaged to measure the shape of the notch portion, measure the chamfer width, and observe the presence or absence of a flaw in the notch portion (Patent Document 2). However, the notch dimension measuring method using the measuring device described in Patent Document 2 measures the width, depth, and chamfer width of the notch, and does not accurately measure the shoulder arc portion radius. Even if this apparatus is used, taking into account the wafer misalignment, inclination, etc. during image capture as described above, an accurate arc passing through the notch shoulder arc end point from the notch shoulder arc start point to the notch V portion on the outer periphery of the wafer. It is difficult to determine the radius of the part, and the shoulder arc radius of the notch cannot be measured with high accuracy.
[0009]
[Patent Document 1]
Japanese Patent Laid-Open No. 7-260432 (paragraph numbers [0009] and [0019], FIG. 1)
[0010]
[Patent Document 2]
JP 10-38539 A (paragraph numbers [0022] to [0026], FIG. 1)
[0011]
[Problems to be solved by the invention]
The present invention has been made in consideration of the above-described circumstances, and an object of the present invention is to provide a method for measuring a shoulder arc portion radius of a wafer notch that can accurately measure a shoulder arc portion radius of a notch.
[0012]
[Means for Solving the Problems]
To achieve the above object, according to one aspect of the present invention, a notch shoulder arc is extracted from image-processed notch contour data of a semiconductor wafer, a start point and an end point of the notch shoulder arc are detected, and an arc This is a method of measuring the radius of the shoulder arc of the notch of the semiconductor wafer to obtain the radius of the notch, and is obtained from the coordinates of the maximum value and the two points of the bottom of the notch to obtain the end point of the notch shoulder arc that is the contact point of the notch V portion. A line segment passing through two points y = a1x + b1 and an approximate straight line y = a2x + b2 obtained by the least square method of each coordinate data from the maximum value to the notch bottom are compared while shifting the coordinates, and the difference is minimized. There is provided a method of measuring a shoulder arc radius of a notch of a semiconductor wafer, wherein an arc line radius is obtained by obtaining an inclination line . As a result, a method for measuring the shoulder arc portion radius of the wafer notch that can accurately and easily measure the shoulder arc portion radius is realized.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of a method for measuring a radius of a shoulder arc of a notch of a semiconductor wafer according to the present invention will be described.
[0015]
The method of measuring the radius of the shoulder arc of the notch of the semiconductor wafer according to the present invention extracts the notch shoulder arc from the image processed notch contour data of the semiconductor wafer and uses an algorithm for the start point and end point of the notch shoulder arc. To detect the arc radius.
[0016]
Next, a method for measuring the radius of the shoulder arc of the notch of the semiconductor wafer according to the present invention will be described with reference to a flowchart for executing the measurement method shown in FIG.
[0017]
As shown in FIG. 2, the notch vicinity contour image coordinate data is extracted from the notch portion image captured by the image processing apparatus, and the minimum value coordinate ( Xm, Ym) is detected (S1).
As shown in FIG. 3, this is detected in the X-axis direction as the notch bottom where Y is minimized, that is, the minimum coordinate (Xm, Ym).
[0018]
The left maximum coordinate (Xl ₁ , Yl ₁ ) and the right maximum coordinate (Xr ₂ , Yr ₂ ) are detected (S2).
As shown in FIG. 3, X is searched in the positive and negative directions from the bottom of the notch, and the left maximum coordinate (Xl ₁ , Yl ₁ ) and the maximum right coordinate (Xr ₁ , X Yr ₁ ) is detected.
[0019]
An equation of the notch tangent Lt is obtained as a line segment connecting the left maximum coordinate (Xl ₁ , Yl ₁ ) and the right maximum coordinate (Xr ₁ , Yr ₁ ) obtained in S2 (S3).
As shown in FIG. 4, equations of left and right tilt lines Ll and Lr are calculated (S4).
[0020]
An equation y = a ₁ x + b ₁ is obtained for a line segment passing through two points obtained from the left side maximum value and the coordinates of the two points at the bottom of the notch. Next, an approximate linear equation y = a ₂ x + b ₂ of each coordinate data from the maximum value on the left side to the bottom of the notch is obtained by the method of least squares. Comparing a ₁ and a _2, b ₁ and b ₂ obtains the equation of the line segment slope similarly while narrowing the sequential section and one minus side from one positive and notch bottom data from the left maximum coordinate side data, A section where this difference is small is found, and a line segment passing through these two points is defined as a left slope line Ll. The right slope line Lr is obtained in the same manner.
[0021]
As shown in FIG. 5, the start point coordinates and end point coordinates of the left and right arc portions are detected, and the arc portions are extracted (S5).
The coordinates of the two points where the contour coordinate data line segment intersects the notch tangent line and the inclination line are set as the start / end position coordinates of the arc part, and the arc part is extracted. Thereby, the positions of the start point and the end point of the notch shoulder arc part can be accurately calculated, and an accurate arc part radius passing from the start point to the end point can be obtained.
[0022]
As shown in FIG. 6, the left and right arc portion intermediate point (3) is detected (S6).
The radius of the three-point arc portion is obtained by setting the point where the vertical bisector of the straight line connecting the intersection point (1) with the notch tangent line and the intersection point (2) between the notched tangent line and the arc portion intersects with the point (3) (S7). .
[0023]
As described above, according to the method for measuring the radius of the shoulder arc of the notch of the semiconductor wafer according to the present invention, it is not necessary to consider the deviation, inclination, etc. of the wafer during image capture, and the starting point of the notch shoulder arc of the outer periphery of the wafer. To the notch shoulder portion, the accurate radius of the arc portion passing through the notch shoulder arc end point can be measured accurately and easily.
[0024]
【The invention's effect】
According to the method for measuring the radius of the shoulder arc of the notch of the semiconductor wafer according to the present invention, it is possible to provide a method of measuring the radius of the shoulder arc of the wafer notch that can accurately and easily measure the radius of the shoulder arc.
[Brief description of the drawings]
FIG. 1 is a flowchart for executing a method of measuring a shoulder arc radius of a notch of a semiconductor wafer according to the present invention.
FIG. 2 is a notch vicinity contour image coordinate data diagram used in a method for measuring a radius of a shoulder arc of a notch of a semiconductor wafer according to the present invention.
FIG. 3 is a calculation diagram of a notch tangent used in the method for measuring the shoulder arc radius of a notch of a semiconductor wafer according to the present invention.
FIG. 4 is an inclination line calculation diagram used in the method for measuring the radius of the shoulder arc of the notch of the semiconductor wafer according to the present invention.
FIG. 5 is an arc extraction diagram used in the method of measuring the shoulder arc radius of the notch of the semiconductor wafer according to the present invention.
FIG. 6 is an arc portion midpoint detection diagram used in the method for measuring the shoulder arc portion radius of a notch of a semiconductor wafer according to the present invention.
FIG. 7 shows a conventional method for measuring a radius of a circular arc portion of a notch tip of a semiconductor wafer.

Claims

Extracting the notch shoulder arc from the image processed notch contour data of the semiconductor wafer, detecting the start and end points of the notch shoulder arc, and determining the arc radius In order to obtain the end point of the notch shoulder arc portion, which is the contact point of the notch V portion, the equation y = a1x + b1 passing through the two points obtained from the maximum value and the coordinates of the two points at the bottom of the notch, and the notch from the maximum value Approximate linear expression y = a2x + b2 obtained by the least square method of each coordinate data to the bottom is compared while shifting the coordinates, and an arc line radius is obtained by obtaining an inclination line that minimizes the difference. To measure the radius of the shoulder arc of a notch.