JPH03173452A - Wafer surface plate pit defects detection optical system - Google Patents
Wafer surface plate pit defects detection optical systemInfo
- Publication number
- JPH03173452A JPH03173452A JP31234789A JP31234789A JPH03173452A JP H03173452 A JPH03173452 A JP H03173452A JP 31234789 A JP31234789 A JP 31234789A JP 31234789 A JP31234789 A JP 31234789A JP H03173452 A JPH03173452 A JP H03173452A
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- Prior art keywords
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- mirror
- hole
- laser
- face plate
- Prior art date
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- 230000007547 defect Effects 0.000 title claims abstract description 47
- 238000001514 detection method Methods 0.000 title claims abstract description 19
- 230000003287 optical effect Effects 0.000 title claims description 24
- 230000035945 sensitivity Effects 0.000 claims abstract description 6
- 238000007689 inspection Methods 0.000 claims description 4
- 238000000034 method Methods 0.000 abstract description 4
- 230000003247 decreasing effect Effects 0.000 abstract 1
- 230000001788 irregular Effects 0.000 abstract 1
- 238000010586 diagram Methods 0.000 description 5
- 230000007423 decrease Effects 0.000 description 2
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 230000000630 rising effect Effects 0.000 description 1
- 239000004065 semiconductor Substances 0.000 description 1
- 229910052710 silicon Inorganic materials 0.000 description 1
- 239000010703 silicon Substances 0.000 description 1
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Abstract
Description
【発明の詳細な説明】
[産業上の利用分野コ
この発明は、面板の欠陥を検査する光学系に関し、詳し
くは表面が鏡面をなすウェハ面板に存在する、比較的面
積が大きく深さが浅い皿吠のピット欠陥を対象とするも
のである。[Detailed Description of the Invention] [Industrial Application Field] This invention relates to an optical system for inspecting defects on a face plate, and more specifically, defects on a wafer face plate with a mirror surface, which have a relatively large area and a shallow depth. This is aimed at pit defects in discs.
[従来の技術]
半導体ICの素材のシリコンウェハ面板には種々の欠陥
があり、これらはICの品質を劣化するので、面板検査
装置により検査されている。[Prior Art] Silicon wafer faceplates, which are the raw material for semiconductor ICs, have various defects, and these defects degrade the quality of the IC, so they are inspected using a faceplate inspection device.
第2図(a)は光学式によるウェハ面板検査装置の光学
系の基本構成を示すもので、投光部2のレーザ光aX
2 aよりのレーザが投光レンズ2bにより集束されて
被検査の面板1にスポットを形成する。図示しない駆動
機構により回転方式またはXY走査方式によりスポット
が面板の全面を走査する。走査中、表面に欠陥が存在す
るときはこれによりレーザが散乱し、この散乱光を受光
部3の集光レンズ3aにより集光して受光器3bの受光
信号により欠陥が検出される。ここで、上記のように欠
陥には種々のものがあり、その代表的なものは第2図(
b)の(イ)に示すような、付着した異物または素材自
身の突起などの凸部と、(ロ)に示す切り傷のような幅
または面積の微小な四部がある。FIG. 2(a) shows the basic configuration of the optical system of an optical wafer face plate inspection device.
2a is focused by a projection lens 2b to form a spot on the face plate 1 to be inspected. A spot scans the entire surface of the face plate using a rotation method or an XY scanning method using a drive mechanism (not shown). During scanning, if a defect exists on the surface, the laser is scattered, and the scattered light is focused by the condensing lens 3a of the light receiving section 3, and the defect is detected by the light reception signal of the light receiver 3b. Here, as mentioned above, there are various types of defects, and the representative ones are shown in Figure 2 (
There are convex parts such as attached foreign matter or protrusions of the material itself as shown in (a) of b), and four parts with small widths or areas such as cuts shown in (b).
これらは、断面上の曲線の変化が急角度であるのでレー
ザの散乱光が比較的に強くて検出が可能である。In these cases, since the curve on the cross section changes at a steep angle, the scattered light of the laser is relatively strong and can be detected.
[解決しようとする課題]
以−Lに対して、第2図(b)の(ハ)に示す比較的に
面積が大きく深さが浅い皿状のピット欠陥とよばれる凹
部は、角度の変化が緩やかであるために散乱光が弱いか
または正反射光が反射されて」;記の光学系の集光レン
ズに十分捕捉されず検出が困難である。これに対する検
出方法が必要とされ、先行技術としてこの発明の出願人
により、「昭和6I年12J]8日、第G+−2922
27号、面板欠陥検出光学装置」が特許出願されている
。[Problem to be solved] In contrast to L, the concave portion called a dish-shaped pit defect, which is relatively large in area and shallow in depth, shown in (c) of Fig. 2(b), is caused by a change in angle. Because the light is slow, the scattered light is weak, or the specularly reflected light is reflected and is not sufficiently captured by the condensing lens of the optical system, making detection difficult. A detection method for this is required, and as a prior art, the applicant of the present invention has published "No.
No. 27, “Face Plate Defect Detection Optical Device” has been applied for a patent.
第3図(a)、(b)は上記の特許出願にかかる面板欠
陥検出光学装置の作用原理と構成要部を示すもので、図
(a)において、レーザのスポットがピット欠陥に対し
て図示左より右方に走査されるとき、ピットの傾斜角が
下降する点pにおける反射光をR1)%平坦な中央部の
点qのそれをRqNまた上昇する点rのそれをRrとす
ると、各反射光は反時計回りに回転する。Rqを除いて
RpとRrを受光することにより、ピット欠陥が検出さ
れる。FIGS. 3(a) and 3(b) show the working principle and main components of the face plate defect detection optical device according to the above patent application. In FIG. 3(a), the laser spot is shown on the pit defect When scanning from the left to the right, the reflected light at the point p where the inclination angle of the pit is falling is R1)%.If the reflected light at the point q in the flat central part is RqN, and that at the point r where the inclination angle is rising is Rr, then each The reflected light rotates counterclockwise. A pit defect is detected by receiving Rp and Rr except for Rq.
ただし、ピット欠陥の凹面は必ずしも平滑でなく段差な
どがあって散乱光が含まれる場合もある。However, the concave surface of a pit defect is not necessarily smooth and may have a step or the like, which may contain scattered light.
図(b)において、レーザ光源2aよりのレーザは投光
レンズ2bとミラー4を経て投受光レンズ5により面板
1に投光され、その表面またはピット欠陥の点qとその
近傍よりの反射光Rqは投受光レンズ5を通った後スト
ッパ6により遮断される。In Figure (b), the laser beam from the laser light source 2a passes through the projection lens 2b and mirror 4, and is projected onto the face plate 1 by the projection/reception lens 5, and reflected light Rq from the surface or pit defect point q and its vicinity. After passing through the light emitting/receiving lens 5, the light is blocked by a stopper 6.
これに対して、点pまたはrを含む近傍の反射または散
乱光RP、Rrは、投受光レンズ5より受光器7に入力
してピット欠陥が検出される。On the other hand, the reflected or scattered lights RP and Rr in the vicinity of points p or r are input to the light receiver 7 through the light projecting/receiving lens 5, and pit defects are detected.
以tに対して、この発明は原理的には同等であるが光学
系を一ヒ記と異なる方法により構成し、さらに検出信号
の処理を改良してピット欠陥の検出性能を向にを計るも
のである。In response to the above, the present invention is similar in principle, but the optical system is constructed using a different method from that described in 1), and the processing of the detection signal is further improved to further improve the pit defect detection performance. It is.
[課題を解決するための手段]
この発明は、表面が鏡面をなすウェハ面板の欠陥検査装
置におけるピア)欠陥検出光学系である。[Means for Solving the Problems] The present invention is a peer defect detection optical system in a defect inspection apparatus for a wafer face plate having a mirror surface.
レーザ光源よりのレーザの光軸に対して45°傾斜した
第1の穴ミラーと、これに対して反射面が直角をなす第
2の穴ミラー、および第1の穴ミラーの中心穴を透過し
たレーザを集束してスポットを形成する投受光レンズと
を具備する。投受光レンズにより投光されたレーザの鏡
面による正反射光を、投受光レンズにおける投光された
レーザの光軸と異なる光軸上において受光し、受光され
たIE反射光を第1の穴ミラーの反射面により反射させ
た後、第2の穴ミラーの中心穴を透過させ、その透過光
を受光する第1の受光器と、ウェハ面板に存在するピッ
ト欠陥により反射角が変化したレーザの正反射光または
乱反射光を、第1および第2の穴ミラーのそれぞれの反
射面により反射させ、その反射光を受光する第2の受光
器、および第1および第2の受光器のそれぞれの出力信
号の差分を演算して感度を向上する差分演算器により構
成されたものである。A first hole mirror tilted at 45° with respect to the optical axis of the laser from the laser light source, a second hole mirror whose reflective surface is perpendicular to this, and a center hole of the first hole mirror that transmits light. It is equipped with a light emitting/receiving lens that focuses the laser to form a spot. The specularly reflected light from the mirror surface of the laser projected by the light projecting/receiving lens is received on an optical axis different from the optical axis of the projected laser in the light projecting/receiving lens, and the received IE reflected light is transmitted to the first hole mirror. After being reflected by the reflective surface of the wafer, it is transmitted through the center hole of the second hole mirror, and the first light receiver receives the transmitted light. A second light receiver that reflects the reflected light or diffusely reflected light by each reflecting surface of the first and second hole mirrors and receives the reflected light, and an output signal of each of the first and second light receivers. It is composed of a difference calculator that calculates the difference between the two and improves the sensitivity.
[作用]
以上の構成によるビット欠陥検出光学系においては、第
1の穴ミラーの中心穴を透過したレーザは、投受光レン
ズの集光によりスポットとされて被検査の面板に投光し
て走査され、欠陥が存在しない鏡面における正反射光は
、投受光レンズと第1の穴ミラーの反射面、および第2
の穴ミラーの中心穴を経て第1の受光器に入力する。一
方、而仮にピット欠陥が存在するときは、正反射光また
は乱反射光の方向が変化するので、投光受光レンズを透
過したこれらは、第1および第2の穴ミラーの反射面に
よりそれぞれ反射されて第2の受光器により受光される
。この場合、ピント欠陥により第2の受光器の出力信号
のレベルは増加するが、この増加分だけ第1の受光器の
出力信号のレベルが低下するので、差分演算器により第
1および第2の受光器の出力信号の差分が演算されて、
ピット欠陥に対する検出感度が2倍に向上するものであ
る。[Function] In the bit defect detection optical system with the above configuration, the laser beam that passes through the center hole of the first hole mirror is focused by the light projecting/receiving lens to form a spot, and is projected onto the face plate to be inspected for scanning. The specularly reflected light on the mirror surface with no defects is reflected by the light emitting/receiving lens, the reflecting surface of the first hole mirror, and the second mirror.
The light is input to the first light receiver through the center hole of the hole mirror. On the other hand, if a pit defect exists, the direction of the specularly reflected light or the diffusely reflected light changes, so that the light transmitted through the light emitting/receiving lens is reflected by the reflecting surfaces of the first and second hole mirrors, respectively. The light is then received by the second light receiver. In this case, the level of the output signal of the second photoreceiver increases due to the focus defect, but the level of the output signal of the first photoreceiver decreases by this increase. The difference between the output signals of the receiver is calculated and
The detection sensitivity for pit defects is doubled.
[実施例コ
第1図(a)、(b)は、この発明によるウェハ面板の
ピット欠陥検出光学系の実施例における構成と作用に対
する説明図である。レーザ光源2aよりのレーザTは投
光レンズ2bによりコリメートされ、その先軸に対して
45°傾斜して設けられた第1の穴ミラー8−1の中心
穴を透過し、平面ミラー4により図示下方に反射される
。このレーザTは、光軸が投受光レンズ5の中心に対し
て図示の左側に偏った位置に投光され、光軸が屈折する
とともに、集束されたスポットがウェハ面板1に投光さ
れる。面板lの表面が鏡面のとき、またはピット欠陥の
平坦部においては、レーザTは正反射され、その正反射
光Rqは図示の実線の経路をとって第1の穴ミラー8−
1の中心穴以外の反射面により反射される。第2の穴ミ
ラー8−2は、第1の穴ミラー8−1に対して直角方向
とされ、かつ上記の正反射光Rqを透過するように中心
穴の位置が設定されているので、正反射光Rqはその中
心穴を透過して第1の受光器7−1に受光される。また
、ピット欠陥の傾斜部または段差などにより正反射また
は乱反射して角度方向が変化した反射光RpまたはRr
は図示の一点鎖線または二点鎖線の経路をとり、第1お
よび第2の穴ミラーの反射面でそれぞれ反射され、この
反射光は集光レンズ9により集光されて第2の受光器7
−2に受光される。Embodiment FIGS. 1(a) and 1(b) are explanatory diagrams of the structure and operation of an embodiment of a pit defect detection optical system for a wafer face plate according to the present invention. The laser T from the laser light source 2a is collimated by the projection lens 2b, passes through the center hole of the first hole mirror 8-1 provided at an angle of 45 degrees with respect to its tip axis, and is reflected by the plane mirror 4 as shown in the figure. reflected downward. This laser T is projected to a position where the optical axis is biased to the left side in the drawing with respect to the center of the light emitting/receiving lens 5, and as the optical axis is refracted, a focused spot is projected onto the wafer face plate 1. When the surface of the face plate l is a mirror surface or at a flat part of a pit defect, the laser T is specularly reflected, and the specularly reflected light Rq takes the path shown by the solid line in the figure to the first hole mirror 8-
It is reflected by reflective surfaces other than the center hole of No. 1. The second hole mirror 8-2 is perpendicular to the first hole mirror 8-1, and the position of the center hole is set so as to transmit the specularly reflected light Rq. The reflected light Rq passes through the center hole and is received by the first light receiver 7-1. In addition, the reflected light Rp or Rr whose angular direction has changed due to specular reflection or diffuse reflection due to the slope or step of the pit defect.
takes the path indicated by the dashed-dotted line or the dashed-double-dotted line, and is reflected by the reflective surfaces of the first and second aperture mirrors, and this reflected light is condensed by the condensing lens 9 and sent to the second light receiver 7.
-2 is received.
第1および第2の受光器のそれぞれの出力信号1111
2は差分演算器10に入力して、差分(I2−Il)が
出力される。第1図(b)は、出力信号11112およ
び(I2−If)の波形の例を示す。If はピント欠
陥がない鏡面の部分に対しであるレベルの信号Rqを示
し、ピット欠陥の反射光Rp、Rrに対してはそのレベ
ルが低下し、これらに対応してI2はレベルが上昇して
おり、両者の差分(I2−It)は、RpとRrの部分
が2倍となって感度が向上している。なお、レーザのス
ポットがピット欠陥の直径より大きいときは、レーザは
平均的に反射されて図示点線のような平均値的な曲線の
出力信号R′となるものである。Output signal 1111 of each of the first and second receivers
2 is input to the difference calculator 10, and the difference (I2-Il) is output. FIG. 1(b) shows an example of the waveforms of the output signals 11112 and (I2-If). If indicates a signal Rq at a certain level for the portion of the mirror surface with no focus defects, and its level decreases for reflected light Rp and Rr from pit defects, and correspondingly, the level of I2 increases. As for the difference between the two (I2-It), the portions of Rp and Rr are doubled, and the sensitivity is improved. Note that when the laser spot is larger than the diameter of the pit defect, the laser is reflected on an average basis, resulting in an output signal R' having an average value curve as shown by the dotted line in the figure.
以上はピット欠陥を対象とするものであるが、この実施
例においては、前記した第2図(a)の集光レンズ3a
と受光器3bよりなる受光部3を併設し、同図(b)の
(イ)に示した異物などの凸部や、(ロ)の微小な凹部
などを検出するものである。The above description deals with pit defects, but in this embodiment, the condenser lens 3a shown in FIG.
A light-receiving section 3 consisting of a light receiver 3b and a light-receiving section 3b are installed together to detect convex parts such as foreign objects shown in (a) of FIG.
「発明の効果コ
以」二の説明により明らかなように、この発明によるピ
ット欠陥検出光学系においては、ウェハ面板に存在する
比較的面積が広<、深さが浅いピ。As is clear from the explanation in ``Effects of the Invention'' 2, in the pit defect detection optical system according to the present invention, the pit defect detection optical system according to the present invention has a relatively large area and a shallow depth on the wafer face plate.
ト欠陥の反射または散乱光の方向が、鏡面に対する正反
射方向に対して変化することを利用し、鏡面の正反射光
の受光と、ピットにおける反射または散乱光の受光とを
別々に受光して、それぞれの出力信号の差分をとるもの
で、検出感度が2倍に増強されて従来困難であったピッ
ト欠陥を効率的に検出できる効果には大きいものがある
。Taking advantage of the fact that the direction of reflected or scattered light from a pit defect changes with respect to the direction of specular reflection on a mirror surface, the specularly reflected light from the mirror surface and the reflected or scattered light from the pits are received separately. , the difference between the respective output signals is taken, and the detection sensitivity is doubled, which has a great effect in efficiently detecting pit defects, which was previously difficult.
第1図(a)および(b)は、この発明によるウェハ面
板のピット欠陥検出光学系の実施例における構成図およ
び受光の出力信号と差分信号の波形図、第2図(a)お
よび(b)は、ウェハ面板欠陥検査装置の通常の光学系
の構成図および代表的な欠陥の説明図、第3図(a)お
よび(b)は、ピット欠陥による反射または散乱光の特
徴の説明図および、特許出願にかかる面板欠陥検出光学
装置の要部の構成図である。
1・・・ウェハ面板、 2・・・投光部、2a・・
・レーザ光源、 2b・・・投光レンズ、3・・・受
光部、 3a・・・集光レンズ、3b・・・受
光器、 4・・・平面ミラー5・・・投受光レン
ズ、 6・・・ストッパ、7・・・受光器、7−1
・・・第1の受光器、7−2・・・第2の受光器、 8
−1・・・第1の穴ミラー8−2・・・第2の穴ミラー
、9・・・集光レンズ、10・・・差分演算器。FIGS. 1(a) and (b) are a block diagram of an embodiment of the pit defect detection optical system for a wafer face plate according to the present invention, waveform diagrams of the output signal of light reception and a difference signal, and FIGS. 2(a) and (b). 3(a) and (b) are diagrams illustrating the characteristics of reflected or scattered light due to pit defects, and FIGS. FIG. 1 is a configuration diagram of a main part of a face plate defect detection optical device according to a patent application. 1... Wafer face plate, 2... Light projecting section, 2a...
- Laser light source, 2b... Light emitting lens, 3... Light receiving section, 3a... Condensing lens, 3b... Light receiver, 4... Plane mirror 5... Light emitting/receiving lens, 6. ...Stopper, 7...Receiver, 7-1
...first light receiver, 7-2...second light receiver, 8
-1...First hole mirror 8-2...Second hole mirror, 9...Condenser lens, 10...Difference calculator.
Claims (1)
いて、レーザ光源よりのレーザの光軸に対して45゜傾
斜した第1の穴ミラーと、該第1の穴ミラーに対して反
射面が直角をなす第2の穴ミラー、および該第1の穴ミ
ラーの中心穴を透過した上記レーザを集束してスポット
を形成する投受光レンズとを具備し、該投受光レンズに
より上記ウェハ面板に投光された該スポットの上記鏡面
による正反射光を、上記授受光レンズにおける上記投光
されたレーザの光軸と異なる光軸上において受光し、該
受光された正反射光を上記第1の穴ミラーの反射面によ
り反射させた後、上記第2の穴ミラーの中心穴を透過さ
せ、該透過した透過光を受光する第1の受光器と、上記
ウェハ面板に存在するピット欠陥により反射角が変化し
た上記レーザの正反射光または乱反射光を、上記第1の
穴ミラーおよび上記第2の穴ミラーのそれぞれの反射面
により反射させ、該反射による反射光を受光する第2の
受光器、および上記第1の受光器と第2の受光器のそれ
ぞれの出力信号の差分を演算して感度を向上する差分演
算器とにより構成されたことを特徴とする、ウェハ面板
のピット欠陥検出光学系。(1) In a defect inspection device for a wafer face plate having a mirror surface, a first hole mirror is inclined at 45 degrees with respect to the optical axis of the laser from a laser light source, and a reflective surface is formed with respect to the first hole mirror. A second hole mirror forming a right angle, and a light projecting/receiving lens that focuses the laser beam transmitted through the center hole of the first hole mirror to form a spot, and the light projecting/receiving lens projects the laser beam onto the wafer face plate. The specularly reflected light of the emitted spot by the mirror surface is received on an optical axis different from the optical axis of the projected laser in the transmitting/receiving lens, and the received specularly reflected light is sent to the first hole. After the light is reflected by the reflective surface of the mirror, it is transmitted through the center hole of the second hole mirror, and the reflection angle is changed by a first light receiver that receives the transmitted light and a pit defect existing in the wafer face plate. a second light receiver that reflects the changed specularly reflected light or diffusely reflected light of the laser by each reflecting surface of the first hole mirror and the second hole mirror, and receives the reflected light resulting from the reflection; A pit defect detection optical system for a wafer face plate, comprising a difference calculator that calculates the difference between output signals of the first light receiver and the second light receiver to improve sensitivity.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP31234789A JP2876482B2 (en) | 1989-12-01 | 1989-12-01 | Face plate inspection system |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP31234789A JP2876482B2 (en) | 1989-12-01 | 1989-12-01 | Face plate inspection system |
Publications (2)
Publication Number | Publication Date |
---|---|
JPH03173452A true JPH03173452A (en) | 1991-07-26 |
JP2876482B2 JP2876482B2 (en) | 1999-03-31 |
Family
ID=18028152
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
JP31234789A Expired - Fee Related JP2876482B2 (en) | 1989-12-01 | 1989-12-01 | Face plate inspection system |
Country Status (1)
Country | Link |
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JP (1) | JP2876482B2 (en) |
Cited By (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US6138424A (en) * | 1998-07-28 | 2000-10-31 | Beutler Heating & Air Conditioning | Vent apparatus for attachment to a building structure |
KR100900618B1 (en) * | 2007-06-20 | 2009-06-02 | 삼성전기주식회사 | Surface measurement apparatus |
CN113588520A (en) * | 2021-04-27 | 2021-11-02 | 深圳迈瑞动物医疗科技有限公司 | Optical detection device and cell analyzer |
-
1989
- 1989-12-01 JP JP31234789A patent/JP2876482B2/en not_active Expired - Fee Related
Cited By (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US6138424A (en) * | 1998-07-28 | 2000-10-31 | Beutler Heating & Air Conditioning | Vent apparatus for attachment to a building structure |
KR100900618B1 (en) * | 2007-06-20 | 2009-06-02 | 삼성전기주식회사 | Surface measurement apparatus |
CN113588520A (en) * | 2021-04-27 | 2021-11-02 | 深圳迈瑞动物医疗科技有限公司 | Optical detection device and cell analyzer |
CN113588520B (en) * | 2021-04-27 | 2024-04-09 | 深圳迈瑞动物医疗科技股份有限公司 | Optical detection device and cell analyzer |
Also Published As
Publication number | Publication date |
---|---|
JP2876482B2 (en) | 1999-03-31 |
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