JPH0460331B2 - - Google Patents
Info
- Publication number
- JPH0460331B2 JPH0460331B2 JP58184433A JP18443383A JPH0460331B2 JP H0460331 B2 JPH0460331 B2 JP H0460331B2 JP 58184433 A JP58184433 A JP 58184433A JP 18443383 A JP18443383 A JP 18443383A JP H0460331 B2 JPH0460331 B2 JP H0460331B2
- Authority
- JP
- Japan
- Prior art keywords
- diffraction grating
- light
- gap
- diffracted
- signal
- 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.)
- Expired - Lifetime
Links
- 238000000034 method Methods 0.000 claims description 7
- 230000001427 coherent effect Effects 0.000 claims description 5
- 238000006073 displacement reaction Methods 0.000 claims description 3
- 235000012431 wafers Nutrition 0.000 description 16
- 238000012545 processing Methods 0.000 description 5
- 238000010586 diagram Methods 0.000 description 4
- 230000000694 effects Effects 0.000 description 3
- 239000004065 semiconductor Substances 0.000 description 2
- 238000001514 detection method Methods 0.000 description 1
- 238000011156 evaluation Methods 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 238000012544 monitoring process Methods 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
- H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
- H01L21/04—Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer
- H01L21/18—Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer the devices having semiconductor bodies comprising elements of Group IV of the Periodic Table or AIIIBV compounds with or without impurities, e.g. doping materials
- H01L21/30—Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26
Landscapes
- Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Condensed Matter Physics & Semiconductors (AREA)
- General Physics & Mathematics (AREA)
- Manufacturing & Machinery (AREA)
- Computer Hardware Design (AREA)
- Microelectronics & Electronic Packaging (AREA)
- Power Engineering (AREA)
- Exposure And Positioning Against Photoresist Photosensitive Materials (AREA)
- Exposure Of Semiconductors, Excluding Electron Or Ion Beam Exposure (AREA)
- Control Of Position Or Direction (AREA)
Description
【発明の詳細な説明】
〔発明の技術分野〕
本発明は半導体ICやLSIを製造するための露光
装置やパタン評価装置に利用されるギヤツプと位
置の高精度アライメントに関するものである。DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to highly accurate alignment of gaps and positions used in exposure devices and pattern evaluation devices for manufacturing semiconductor ICs and LSIs.
半導体ICやLSIの微細化に伴い、マスクパタン
をウエハに一括しもしくはステツプアンドリピー
ト方式によつて露光・転写する装置において、マ
スクとウエハを互いに高精度に位置合せする技術
の確立は不可欠であり、特に、サブミクロンパタ
ンを露光・転写するＸ線露光装置では高精度位置
合せとともに、マスクとウエハ間のギヤツプを高
精度で一定値に設定する技術の確立が欠かせない
ものとなつている。
With the miniaturization of semiconductor ICs and LSIs, it is essential to establish technology for aligning the mask and wafer with high precision in equipment that exposes and transfers mask patterns to wafers all at once or using a step-and-repeat method. In particular, in X-ray exposure equipment that exposes and transfers submicron patterns, it is essential to establish a technology for highly accurate positioning and for setting the gap between the mask and the wafer to a constant value with high accuracy.
この一方式として、例えばJ.Vac.Sci.Technol.
Vol.19，No.４，1981，P214で紹介されているよ
うに、0.1μm以下の位置合せを行うことを目的と
して２重回折格子を用いた位置合せ法の開発が進
められている。この方法は、第１図に示す第１の
物体１に設けた第１の回折格子２と、第２の物体
３に設けた第２の回折格子４とを一定ギヤツプＺ
をおいて重ね、これら第１および第２の回折格子
にコヒーレント光もしくは準単色光を垂直に入射
し、両回折格子によつて入射光に対して対称的な
方向に回折された同次数の回折光、例えば±１次
の回折光の強度を減算処理し、その差分強度の変
化によつて第１の物体と第２の物体の相対変位を
検出して位置合せするものであるが、第２図に示
すように、ギヤツプのわずかの変化によつて位置
合せ信号が大きく変化するため実用は困難であつ
た。すなわち、第２図は波長λ＝0.6328μm、回
折格子のピツチＰ＝2μmとした場合について、第
１・第２の物体の位置ずれ量ｄ（μm）と上記差分
強度ΔIとの関係を示したもので、図中イ，ロ，
ハがそれぞれギヤツプＺを6.1，6.2，6.3（μm）と
した場合に対応する。 For example, J.Vac.Sci.Technol.
As introduced in Vol. 19, No. 4, 1981, P214, an alignment method using a double diffraction grating is being developed with the aim of achieving alignment of 0.1 μm or less. In this method, a first diffraction grating 2 provided on a first object 1 and a second diffraction grating 4 provided on a second object 3 shown in FIG.
Coherent light or quasi-monochromatic light is vertically incident on these first and second diffraction gratings, and the same order of diffraction is diffracted by both diffraction gratings in a direction symmetrical to the incident light. The intensity of light, for example, ±1st-order diffracted light, is subtracted, and the relative displacement of the first object and the second object is detected and aligned based on the change in the difference in intensity. As shown in the figure, a slight change in the gap causes a large change in the alignment signal, making it difficult to put it into practical use. That is, Figure 2 shows the relationship between the amount of positional deviation d (μm) of the first and second objects and the above-mentioned differential intensity ΔI when the wavelength λ = 0.6328 μm and the pitch P of the diffraction grating = 2 μm. In the figure, A, B,
C corresponds to the case where the gap Z is 6.1, 6.2, and 6.3 (μm), respectively.
このような変化は、第１図に示した回折光のＡ
とＢ、すなわち第１の物体の裏面、すなわち回折
格子２を設けた面で反射する回折光Ａと、第１の
物体１を通過し第２の物体３で垂直に反射し、改
めて第１の物体で回折する光Ｂとの干渉の影響が
原因しているものと考えられる。 Such a change is caused by the A of the diffracted light shown in Figure 1.
and B, that is, the diffracted light A that is reflected on the back surface of the first object, that is, the surface on which the diffraction grating 2 is provided, and the diffracted light A that passes through the first object 1 and is vertically reflected by the second object 3, and is reflected again on the first object. This is thought to be caused by the influence of interference with the light B diffracted by the object.
本発明は、このような事情に鑑みてなされたも
ので、その目的は、ギヤツプ制御と位置合せ制御
とを同時にかつ高精度に行なうことが可能な２重
回折格子によるギヤツプ・位置合せ制御法を提供
することにある。
The present invention has been made in view of the above circumstances, and its purpose is to provide a gap/alignment control method using a double diffraction grating that allows gap control and alignment control to be performed simultaneously and with high precision. Our goal is to provide the following.
このような目的を達成するために、本発明は入
射光に対して対称的な方向に回折された、第１の
物体の第１の回折格子を設けた面で直接反射回折
した光を含むすべての同時数の回折光強度を加算
処理し、この加算強度の変化によつてギヤツプお
よび位置合せ制御を行なうものである。 In order to achieve such an object, the present invention is directed to all the light including the light directly reflected and diffracted by the surface of the first object provided with the first diffraction grating, which is diffracted in a direction symmetrical to the incident light. The simultaneous number of diffracted light intensities are added, and gap and alignment control is performed based on changes in the added intensities.
第３図は本発明の一実施例を示す構成図であ
り、１１はウエハ、１２はウエハに設けた回折格
子、１３はマスク、１４はマスクに設けた回折格
子、１５はレーザ光源、１６，１７は光電変換
器、１８は信号処理制御部、１９はマスク微調ス
テージ、２０はウエハ微調ステージを示す。
FIG. 3 is a configuration diagram showing an embodiment of the present invention, in which 11 is a wafer, 12 is a diffraction grating provided on the wafer, 13 is a mask, 14 is a diffraction grating provided on the mask, 15 is a laser light source, 16, 17 is a photoelectric converter, 18 is a signal processing controller, 19 is a mask fine adjustment stage, and 20 is a wafer fine adjustment stage.
上記構成において、レーザ光源１５から発した
コヒーレント光は、真空吸着ホルダーによつて保
持されるマスク１３上の回折格子１４に入射す
る。マスクの回折格子によつて回折した光は、微
調ステージ２０上に保持されるウエハ１１上に作
成された回折格子１２で反射し、再度マスク上の
回折格子１４を通過する。 In the above configuration, coherent light emitted from the laser light source 15 is incident on the diffraction grating 14 on the mask 13 held by the vacuum suction holder. The light diffracted by the diffraction grating of the mask is reflected by the diffraction grating 12 formed on the wafer 11 held on the fine adjustment stage 20, and passes through the diffraction grating 14 on the mask again.
これらウエハおよびマスクの回折格子で回折し
た光のうち、＋１次と−１次の回折光のみを光電
変換器１６、１７で受け、その光強度を電気信号
に変換する。 Of the lights diffracted by the diffraction gratings of the wafer and mask, only the +1st-order and -1st-order diffracted lights are received by photoelectric converters 16 and 17, and the light intensity is converted into an electrical signal.
次に、信号処理部１８で＋１次の回折光強度
I+1と−１次の回折光強度I-1を加算し、ΣI＝I+1＋
I-1を求める。 Next, in the signal processing unit 18, the +1st-order diffracted light intensity is
Add I +1 and -1st order diffracted light intensity I -1 , ΣI=I +1 +
Find I -1 .
この加算強度ΣIのギヤツプＺに対する変化は、
第４図に示すようにP2／λごとにピークをもつ
信号と、マスク１３の裏面、すなわち回折格子１
４を設けた面における反射の影響で生ずるλ／２
を周期とする信号とが重畳した信号として示され
る。P2／λ，2P2／λ……でピークをもつ信号
は、マスク裏面での反射を零とした理想条件下で
得られるものであり、この信号は、λ／２で変化
する信号を積分器等によつて処理することによ
り、その包絡線として得ることができる。したが
つて、この包絡線を監視しながらその最大値にマ
スク・ウエハ間のギヤツプＺを調整することによ
つてP2／λ，2P2／λ，……のギヤツプ値に設定
することが可能となる。もし、上記包絡線の最大
値近傍が緩やかな変化を示す場合には、さらに微
分値をとるなどの処理を行なうことによつて、最
大値の検出を容易にすることができる。 The change in this additional strength ΣI with respect to the gap Z is
As shown in FIG. 4, a signal having a peak at each P 2 /λ and
λ/2 caused by the influence of reflection on the surface where 4 is provided
It is shown as a superimposed signal with a signal having a period of . A signal with a peak at P 2 /λ, 2P 2 /λ... is obtained under ideal conditions with zero reflection on the back surface of the mask, and this signal is obtained by integrating a signal that changes at λ/2. By processing it with a device etc., it can be obtained as its envelope. Therefore, by adjusting the gap Z between the mask and wafer to its maximum value while monitoring this envelope, it is possible to set the gap values of P 2 /λ, 2P 2 /λ, ... becomes. If the vicinity of the maximum value of the envelope shows a gradual change, the maximum value can be easily detected by further processing such as taking a differential value.
さらに、この包絡線の最大値はλ／２の周期を
もつ信号のピーク値と一致もしくは±λ／４の範
囲内で一致する。このため、このλ／２の周期を
もつ信号をフイードバツク信号として用いること
によつて、±λ／４以下の精度でギヤツプ制御が
可能となる。すなわち、第４図において、P2／
λごとにピークをもつ信号(イ)を粗合せ信号として
その最大点を検出し、さらにλ／２を周期とする
信号(ロ)を微合せ信号として、領域Ｇで微合せ制御
を行なうことができる。 Further, the maximum value of this envelope coincides with the peak value of a signal having a period of λ/2 or within a range of ±λ/4. Therefore, by using this signal having a period of λ/2 as a feedback signal, gap control can be performed with an accuracy of ±λ/4 or less. That is, in FIG. 4, P 2 /
It is possible to perform fine adjustment control in region G by using the signal (a) that has a peak for each λ as a coarse adjustment signal and detecting its maximum point, and then using the signal (b) with a period of λ/2 as a fine adjustment signal. can.
次に、このようなギヤツプ条件での位置ずれ量
に対する加算強度ΣIの変化は、第５図に示すよ
うにずれ量がＰ／２のときに最大、０のときに最
小を示す。この傾向は同図に示すようにギヤツプ
が1μm程度変化しても変わらず、その最大、最小
値をとる位置ずれ量はほとんど変化しない。すな
わち、第５図において、イ，ロ，ハはそれぞれギ
ヤツプＺが14.22，14.72，15.22（μm）の場合の位
置ずれ量ｄと加算強度ΣIとの関係を示す。なお、
回折格子のピツチＰは3.0μmである。したがつ
て、この加算強度ΣIは位置合せ信号としても十
分に使用可能である。すなわち、ギヤツプ合せ信
号の最大値で位置ずれを起こさせ、位置ずれ量が
Ｐ／２のときに位置合せ信号が最大となる。 Next, as shown in FIG. 5, the change in the addition strength ΣI with respect to the amount of positional deviation under such a gap condition is maximum when the amount of deviation is P/2, and minimum when the amount of deviation is 0. As shown in the figure, this tendency does not change even if the gap changes by about 1 μm, and the amount of positional deviation that takes the maximum and minimum values hardly changes. That is, in FIG. 5, A, B, and C show the relationship between the positional deviation amount d and the addition intensity ΣI when the gap Z is 14.22, 14.72, and 15.22 (μm), respectively. In addition,
The pitch P of the diffraction grating is 3.0 μm. Therefore, this added strength ΣI can also be fully used as an alignment signal. That is, the positional deviation is caused by the maximum value of the gap alignment signal, and the alignment signal becomes maximum when the positional deviation amount is P/2.
このため、予めウエハとマスクに作製した回折
格子マークをＰ／２分だけずらして設けておけ
ば、ギヤツプ、位置ともΣIの最大値を検出する
ことによつて高精度に合せることが可能となる。
あるいはまた、はじめにギヤツプを設定した後、
位置ずれ変化の最小値に合せることによつて、位
置合せが可能となる。 Therefore, if the diffraction grating marks made on the wafer and mask are shifted by P/2 in advance, it is possible to match them with high precision by detecting the maximum value of ΣI for both the gap and position. .
Alternatively, after first setting the gap,
Alignment is possible by adjusting to the minimum value of the change in positional deviation.
これらいずれの方法でも位置合せは可能である
が、格子のラインアンドスペースが１：１から大
きくずれる場合には、位置の最小値検出の方が有
利である。 Alignment is possible using any of these methods, but if the line-and-space ratio of the grating deviates significantly from 1:1, detection of the minimum position value is more advantageous.
以上の２つのギヤツプと位置の合せを交互に行
なうことによつて、マスク、ウエハ上の１対の回
折格子から位置、ギヤツプの同時検出が可能とな
る。 By alternately performing the above two gap and position alignments, it is possible to simultaneously detect the position and gap from a pair of diffraction gratings on the mask and wafer.
以上、１次回折光を利用した場合を例に説明し
たが、本発明はこれに限定されるものではなく、
より高次の回折光を利用しても同様の効果を得る
ことができる。また、上述した実施例ではマス
ク、ウエハにそれぞれ１つの回折格子マークを作
製した場合についてのみ説明したが、例えば特開
昭53−22759号において説明されているようにｘ，
ｙ軸方向に直交する回折格子を１組としてマーク
を作製すると、ｘ，ｙ軸両方向について同時にギ
ヤツプ設定および位置合せ制御ができ、さらにも
う１つのマークを別に設けることによりマスク、
ウエハ間の平行度をきわめて高精度に制御でき
る。また、レーザ光源から発するコヒーレント光
の代りに準単色光を用いても同様の効果が得られ
る。 Although the above example uses the first-order diffracted light, the present invention is not limited to this.
A similar effect can be obtained by using higher-order diffracted light. Furthermore, in the above-mentioned embodiments, only one diffraction grating mark was formed on the mask and the wafer.
If a mark is made using a set of diffraction gratings orthogonal to the y-axis direction, gap setting and alignment control can be performed simultaneously in both the x- and y-axis directions, and by providing another mark separately, the mask,
The parallelism between wafers can be controlled with extremely high precision. Further, similar effects can be obtained by using quasi-monochromatic light instead of coherent light emitted from a laser light source.
以上説明したように、本発明によれば、２重回
折格子に垂直に入射した光に対し、対称的な方向
に回折された同次数の回折光強度を、第１の物体
の回折格子を設けた面で直接反射回折した光を含
めて加算処理し、その加算強度を用いることによ
つて、ギヤツプの高精度設定・制御が可能となる
とともに、高精度な位置合せも同時に可能とな
り、簡単な格子マークによつて100Aオーダの位
置・ギヤツプ設定を行なうことができる。
As explained above, according to the present invention, for light incident perpendicularly on a double diffraction grating, the intensity of diffracted light of the same order diffracted in a symmetrical direction is transferred to the diffraction grating of the first object. By adding the light that is directly reflected and diffracted on the provided surface and using the added intensity, it is possible to set and control the gap with high precision, and at the same time, it is possible to perform high-precision positioning, making it easy to use. Position and gap settings on the order of 100A can be performed using grid marks.
第１図は２重回折位置合せ方の原理図、第２図
は従来の差分強度を用いた位置合せ信号を示す
図、第３図は本発明の一実施例を示す構成図、第
４図はギヤツプ合せ信号としての加算強度信号を
示す図、第５図は位置合せ信号としての加算強度
信号を示す図である。
１１……ウエハ（第２の物体）、１２……ウエ
ハ上に設けた回折格子（第２の回折格子）、１３
……マスク（第１の物体）、１４……マスクに設
けた回折格子（第１の回折格子）、１５……レー
ザ光源、１６，１７……光電変換器、１８……信
号処理部、１９……マスク微調ステージ、２０…
…ウエハ微調ステージ。
FIG. 1 is a principle diagram of the double diffraction alignment method, FIG. 2 is a diagram showing a conventional alignment signal using differential intensity, FIG. 3 is a configuration diagram showing an embodiment of the present invention, and FIG. The figure shows an added intensity signal as a gap alignment signal, and FIG. 5 shows an added intensity signal as a position alignment signal. 11... Wafer (second object), 12... Diffraction grating provided on the wafer (second diffraction grating), 13
... Mask (first object), 14 ... Diffraction grating provided on mask (first diffraction grating), 15 ... Laser light source, 16, 17 ... Photoelectric converter, 18 ... Signal processing section, 19 ...Mask fine adjustment stage, 20...
...Wafer fine adjustment stage.
Claims (1)
の物体に設けた第２の回折格子とを一定のギヤツ
プをおいて重ね、これら第１および第２の回折格
子にコヒーレント光もしくは準単色光を入射し、
両回折格子によつて生じた回折光の強度の変化に
よつて第１の物体と第２の物体の相対変位を検出
して位置合せする装置において、前記コヒーレン
ト光もしくは準単色光を第１の物体に垂直に入射
させ、入射光に対して対称的な方向に回折され
た、第１の物体の第１の回折格子を設けた面で直
接反射回折した光を含むすべての同次数の回折光
強度を加算処理し、この加算強度の変化によつて
第１の物体と第２の物体間のギヤツプを制御する
とともに第１の物体と第２の物体の相対変位を検
出し位置合せ制御することを特徴とする２重回折
格子によるギヤツプ・位置合せ制御法。1 A first diffraction grating provided on a first object, and a second diffraction grating provided on a first object.
A second diffraction grating provided on an object is overlapped with a certain gap, and coherent light or quasi-monochromatic light is incident on these first and second diffraction gratings,
In a device that detects and aligns relative displacement between a first object and a second object by a change in the intensity of diffracted light generated by both diffraction gratings, the coherent light or quasi-monochromatic light is All diffracted light of the same order, including light that is incident perpendicularly to the object and diffracted in a direction symmetrical to the incident light, is directly reflected and diffracted on the surface of the first object provided with the first diffraction grating. Adding the intensities, controlling the gap between the first object and the second object by changing the added intensities, and detecting the relative displacement between the first object and the second object to control the alignment. A gap/alignment control method using a double diffraction grating characterized by:
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP58184433A JPS6077423A (en) | 1983-10-04 | 1983-10-04 | Controlling method for gap and alignment with double diffraction grating |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP58184433A JPS6077423A (en) | 1983-10-04 | 1983-10-04 | Controlling method for gap and alignment with double diffraction grating |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS6077423A JPS6077423A (en) | 1985-05-02 |
| JPH0460331B2 true JPH0460331B2 (en) | 1992-09-25 |
Family
ID=16153064
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP58184433A Granted JPS6077423A (en) | 1983-10-04 | 1983-10-04 | Controlling method for gap and alignment with double diffraction grating |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS6077423A (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2006013400A (en) * | 2004-06-29 | 2006-01-12 | Canon Inc | Method and apparatus for detecting relative positional deviation between two objects |
| NL2003871A (en) | 2009-02-04 | 2010-08-05 | Asml Netherlands Bv | Imprint lithography. |
| JP5284212B2 (en) * | 2009-07-29 | 2013-09-11 | 株式会社東芝 | Manufacturing method of semiconductor device |
-
1983
- 1983-10-04 JP JP58184433A patent/JPS6077423A/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| JPS6077423A (en) | 1985-05-02 |
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