JP2006201288A - Microscopic observation apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a microscopic observation apparatus for directly irradiating supply passes with UV and performing UV-sterilization, dispensing with a process of heating the inside walls of pure water supply/recovery passes arranged in a lens barrel for an objective lens and a process of making medical fluid flow in the passes. <P>SOLUTION: At the bright field observation, a half mirror 7 is located on the position of the optical axis (L1) of the liquid-immersion objective lens 8, and nearly half the UV emitted from an illuminating optical source 2 is vertically emitted on a wafer W. At the sterilization, a reflection mirror 30 is shifted to the optical axis (L1) of the liquid-immersion objective lens 8. Regarding the UV emitted from the illuminating optical source 2, the central UV never advance toward the liquid-immersion objective lens 8 due to the round hole 30a of the reflection mirror 30. On the other hand, the UV reflected by the ambient mirror surface 30b advances along the center axis (L2) of the pure water supply/recovery passes 21 and 22, then, enters the pure water supply/recovery passes 21 and 22 through a cover glass 25, then, the pure water PW in each pass is sterilized. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a microscope observation apparatus used for immersion observation of an object, and more particularly to a microscope observation apparatus suitable for immersion observation of a semiconductor wafer or a liquid crystal substrate.

  In the manufacturing process of semiconductor circuit elements and liquid crystal display elements, a microscope observation apparatus for immersion observation is used for observing defects or foreign matters in circuit patterns formed on a semiconductor wafer or liquid crystal substrate (generally referred to as “substrate”). Yes.

  A pure water supply flow path and a pure water recovery flow path are formed outside the lens barrel of the objective lens so that the structure around the objective lens can be simplified and the pure water supply / recovery mechanism can be arranged. A pure water supply / recovery mechanism has been proposed in which pure water is supplied and recovered between the tip of the objective lens and the substrate (see, for example, Patent Document 1).

  As a technique for improving the resolution without changing the wavelength of the observation light short, a liquid immersion method is generally used.

  The resolution is generally defined by the following equation.

Resolution = k × λ / NA
Where λ is an observation wavelength, NA is an objective opening angle (sin θ), and k is a constant.

  The value of k is 0.5 when discussing the resolution between two lines.

  Therefore, increasing the objective NA is effective for improving the resolution. However, in the air, since the refractive index is 1, it can be realized only up to NA ≦ 1.

  Here, if a medium having a refractive index n is filled between the objective tip and the workpiece, the NA is improved by n times the refractive index of the medium. For example, in the case of water, since n = about 1.3 (which varies depending on the wavelength), the NA can be 1 or more.

  When the immersion method is applied during semiconductor wafer observation or projection exposure, it is necessary to prevent the generation and propagation of microorganisms in the pure water production apparatus and in all the piping. Conventionally, the following method has been adopted as a sterilizing method for microorganisms.

Examples of the constant sterilization method include “UV sterilization method”. In this method, a UV germicidal lamp having a peak power of a wavelength near 260 nm is attached to a water circulation path inside the pure water production apparatus to perform sterilization (see, for example, Patent Document 2).
JP 11-895044 A JP-A-8-66677

  Although the UV sterilization method is a very effective sterilization method, it is not sufficient to sterilize the entire pipe line.

  The present invention has been made in view of the above-described circumstances, and heat is applied to the inner walls of the pure water supply channel and the pure water recovery channel provided in the lens barrel of the objective lens, or a chemical solution is allowed to flow. An object of the present invention is to provide a microscope observation apparatus capable of performing UV sterilization by directly irradiating ultraviolet rays without doing so.

In order to achieve the above object, a microscope observation apparatus according to claim 1 of the present invention is provided in a lens barrel of an objective lens, and includes a pure water supply channel that supplies pure water near a focal position of the objective lens,
Provided in the lens barrel, and a pure water recovery flow path for recovering pure water from the vicinity of the focal position;
A light source that emits ultraviolet light;
Guiding means for guiding and irradiating the ultraviolet rays from the light source to at least the pure water supply flow path.

  The microscope observation apparatus according to claim 2 of the present invention is characterized in that the guide means guides and irradiates the ultraviolet light from the light source to the pure water recovery channel.

In the microscope observation apparatus according to claim 3 of the present invention, the guide means includes:
Half mirror for bright field observation,
A reflection mirror having an opening in the center and a reflection part in the periphery;
At the time of bright field observation, the ultraviolet light from the light source is reflected by the half mirror for bright field observation and guided to the observation target, while at the time of sterilization, the ultraviolet light from the light source is reflected by the reflection mirror to supply the pure water. Mirror switching means for switching the both mirrors so as to guide the flow path or the pure water recovery flow path.

In the microscope observation apparatus according to claim 4 of the present invention, the guide means includes:
It has a transmission member that is provided in the lens barrel and guides the ultraviolet rays reflected by the mirror through the pure water supply channel or the pure water recovery channel.

In the microscope observation apparatus according to claim 5 of the present invention, the guide means includes:
A reflection member provided at a tip of the lens barrel and configured to reflect ultraviolet rays guided in the pure water supply channel or the pure water recovery channel toward pure water in the vicinity of a focal position of the objective lens; It is characterized by that.

In the microscope observation apparatus according to claim 6 of the present invention, the guide means includes:
It has a transmissive lens barrel of an objective lens formed of a material that transmits ultraviolet rays.

  The microscope observation apparatus according to a seventh aspect of the present invention is characterized in that the light source is arranged around the transmissive barrel.

In the microscope observation apparatus according to claim 8 of the present invention, the guide means includes:
An optical fiber for guiding ultraviolet rays from the light source;
And an irradiating member that irradiates the ultraviolet light guided by the optical fiber from the periphery of the transmissive barrel toward the pure water supply channel or the pure water recovery channel.

  According to the present invention, the pure water supply channel or the pure water is configured to guide and irradiate the ultraviolet light from the light source emitting ultraviolet rays to the pure water supply channel or the pure water recovery channel. UV sterilization can be performed by directly irradiating ultraviolet rays without applying heat or flowing a chemical solution to the inner wall of the recovery channel.

  In addition, since UV sterilization is performed using the time when the microscope is not observed, the pure water supply / recovery flow path of the objective lens, which is difficult to sterilize, is frequently washed without reducing the throughput of the apparatus to prevent bacterial growth. The quality of pure water can be kept high.

  In other words, the pure water supply / recovery channel around the objective lens that is most difficult to sterilize can be easily sterilized. Accordingly, particulate contamination caused by microorganisms can be greatly reduced, and the yield of semiconductor devices can be improved. In addition, in an apparatus that attaches importance to throughput, such as a wafer overview inspection apparatus, UV sterilization can always be performed without reducing the processing speed.

  Hereinafter, a microscope observation apparatus according to an embodiment of the present invention will be described with reference to the drawings.

(First embodiment)
FIG. 1 is a schematic diagram of a microscope observation apparatus according to the first embodiment of the present invention.

  The microscope apparatus 1 is equipped with an ultraviolet illumination light source 2 having a wavelength of 200 to 300 nm. The ultraviolet light emitted from the illumination light source 2 passes through the collector lens 3, the aperture stop (AS) 4, the field stop (FS) 5, and the condenser lens 6, and is bent by the bright-field half mirror 7. The light passes through the lens 8 and is irradiated as parallel light on the wafer W (Kohler illumination).

  The ultraviolet light irradiated on the wafer W passes through the half mirror 7 via the immersion objective lens 8, passes through the second objective lens 9 and the bending mirror 10, and the folding mirror 10 and the eyepiece 11. An image formed during the period is formed on the observer's eye (or CCD 12) with the eyepiece 11.

  The microscope apparatus 1 is provided with an XY stage 13, and a Z stage 14 is mounted on the XY stage 13. A wafer holding member 15 that holds the wafer W by means such as vacuum suction is mounted on the Z stage 14. The wafer W is transferred onto the wafer holding member 15 by a wafer transfer means (not shown).

  The lens barrel 20 of the immersion objective lens 8 includes a pure water supply channel 21 for supplying pure water PW near the focal position of the immersion objective lens 8 and pure water from the vicinity of the focal position, as will be described in detail later. A pure water recovery flow path 22 for recovering PW is formed.

  The deionized water PW generated from the deionized water source 16 (deionized water production apparatus or the like) 16 passes through the supply pipe 23 and the deionized water supply passage 21 of the lens barrel 20 by a fixed discharge pump 17 or the like to reach a certain amount. It is supplied to the sample (wafer W) surface. The pure water PW after immersion observation is collected in the drainage recovery tank 19 via the pure water recovery flow path 22 and the recovery pipe 24 of the lens barrel 20 by the negative pressure generated in the vacuum source 18.

  2A is a cross-sectional view of the immersion objective lens shown in FIG. 1, and FIG. 2B is a view taken in the direction of arrow b in FIG.

  The lens barrel 20 of the immersion objective lens 8 includes a metal piece 20a for fixing lens elements at a predetermined interval, a metal cylindrical member 20b formed so as to cover the outside of the metal piece 20a, and a lower part of the cylindrical member 20b. And an attached annular member 20c.

  In the cylindrical member 20b, a pure water supply channel 21 for supplying pure water PW near the focal position of the immersion objective lens 8 so as to be substantially parallel to the optical axis (L1) of the immersion objective lens 8, A pure water recovery flow path 22 for recovering pure water PW from the vicinity of the focal position is formed.

  The pure water supply channel 21 is connected to a supply pipe 23 that communicates with the pure water source (pure water production apparatus or the like) 16 described above. The pure water recovery channel 22 communicates with the drainage recovery tank 19 described above. The collected recovery pipe 24 is connected.

  The pure water supply channel 21 and the supply pipe 23 and the pure water recovery channel 22 and the recovery pipe are paired with each other, but the number and the like are not limited to the illustrated example and can be selected as appropriate. It is.

  Above the pure water supply channel 21 and the pure water recovery channel 22, a ring-shaped cover glass 25 (transmission member) that transmits ultraviolet rays is mounted. The pure water supply channel 21 and the pure water recovery channel 22 are irradiated with ultraviolet rays, while the gap is closed to prevent the pure water PW from leaking.

  3A is a cross-sectional view of the immersion objective lens shown in FIG. 1, FIG. 3B is a view taken in the direction of the arrow b in FIG. 3A, and FIG. 3C is the arrow in FIG. It is an arrow view of c.

  FIG. 4A is a schematic diagram (a view taken along the line III-III in FIG. 1) showing a switching state between a half mirror and a reflection mirror for bright field observation, and FIG. 4B is a half mirror for bright field observation. It is a schematic diagram which shows the reflection state of the light of a reflective mirror.

  The half mirror 7 for bright field observation and the reflection mirror 30 having a round hole 30a in the center and a reflection part (mirror surface 30b) in the periphery are configured to be switchable.

  That is, the bright-field observation half mirror 7 and the reflection mirror 30 are arranged on a movable stage (not shown), and have a structure that can be accurately moved by a certain moving distance (X).

  During normal bright field observation, the half mirror 7 is at the position of the optical axis (L1) of the immersion objective lens 8. In this case, approximately half of the ultraviolet light coming from the illumination light source 2 is incident on the wafer W via the immersion objective lens 8, and approximately half of the reflected light from the wafer W is guided to the eyepiece lens 11. It has become.

  In this embodiment, dark field observation is not performed in principle. As will be described later, the pure water PW is sterilized when the wafer W is loaded / unloaded.

  That is, at the time of sterilization, the reflection mirror 30 is moved to the optical axis (L1) position of the immersion objective lens 8.

  Since the ultraviolet light emitted from the illumination light source 2 is the circular hole 30a at the center of the reflection mirror 30, the ultraviolet light at the center does not go in the direction of the immersion objective lens 8.

  On the other hand, the ultraviolet light reflected by the peripheral mirror surface 30b is applied to the central axis (L2) of the pure water supply / recovery channels 21, 22 as shown in FIGS. 2 (a) and 3 (a). Then, the light enters the pure water supply / recovery flow paths 21 and 22 through the cover glass 25 (transmission member), and sterilizes the pure water PW inside.

  3A, below the cylindrical member 20b of the lens barrel 20, the ultraviolet light guided into the pure water supply / recovery channels 21 and 22 is focused on the immersion objective lens 8. A concave mirror 31 (reflecting member) that reflects toward the pure water PW near the position is provided.

  Even during normal bright-field observation, the amount of ultraviolet light reflected by the peripheral part of the half mirror 7 is less than that during sterilization, but is incident on the pure water supply / recovery channels 21 and 22, Sterilize water PW. You may comprise this peripheral part in a total reflection mirror. Of course, this case is also within the scope of the present invention.

  In the present embodiment, microscopic observation and sterilization are performed according to the following operation sequence.

  The wafer W is mounted on the wafer holding member 15 on the XY stage 13 and the Z stage 14 of the microscope apparatus 1 by a wafer transfer means (not shown). The wafer W is fixed to the wafer holding member 15 by means such as vacuum suction. On the XY stage 13, the point to be observed in the wafer W is moved directly under the objective.

  After a predetermined amount of pure water PW is discharged from the pure water supply channel 21 onto the wafer W, the Z stage 14 moves to focus the objective, and then bright field observation of the wafer W is performed.

  In this bright field observation, as described above, the amount of ultraviolet light reflected by the peripheral part of the half mirror 7 is smaller than that at the time of sterilization, but enters the pure water supply / recovery channels 21 and 22. Pure water PW can be sterilized.

  After the bright field observation is completed, the vacuum source 18 is activated, or vacuum is supplied to the pure water recovery passage 22 by an opening / closing means such as an electromagnetic valve (not shown). By this vacuum, the pure water PW on the wafer W is sucked from the pure water recovery passage 22 together with the surrounding air and recovered.

  Since this microscope is exclusively for bright field observation, the half mirror 7 is on the optical axis (L1) of the immersion objective lens 8 except during sterilization.

  After completion of the bright field observation, the wafer W is unloaded onto the wafer holding member 15, and then the reflection mirror 30 is moved to the position of the optical axis (L 1) of the immersion objective lens 8 using the time for loading the wafer W. Move to.

  At this time, as described above, since the ultraviolet light emitted from the illumination light source 2 is the circular hole 30a at the center of the reflection mirror 30, the ultraviolet light at the center does not go in the direction of the immersion objective lens 8.

  On the other hand, the ultraviolet light reflected by the peripheral mirror surface 30b is applied to the central axis (L2) of the pure water supply / recovery channels 21, 22 as shown in FIGS. 2 (a) and 3 (a). Then, the light enters the pure water supply / recovery flow paths 21 and 22 through the cover glass 25 (transmission member), and sterilizes the pure water PW inside. Further, as shown in FIG. 3A, the ultraviolet light guided into the pure water supply / recovery channels 21 and 22 by the concave mirror 31 (reflecting member) provided below the cylindrical member 20b of the lens barrel 20 is generated. The pure water PW is sterilized by reflecting toward the pure water PW near the focal position of the immersion objective lens 8.

  As described above, in this embodiment, since UV sterilization is performed using a time during which microscopic observation is not performed, the pure water supply / recovery flow channel 21 of the immersion objective lens 8 that is difficult to sterilize without reducing the throughput of the apparatus, 22 is frequently washed to prevent the growth of bacteria and maintain the quality of pure water high.

  In other words, the pure water supply / recovery channels 21 and 22 around the immersion objective lens 8 that is most difficult to sterilize can be easily sterilized. Accordingly, particulate contamination caused by microorganisms can be greatly reduced, and the yield of semiconductor devices can be improved. In addition, in an apparatus that attaches importance to throughput, such as the wafer W overview inspection apparatus, UV sterilization can always be performed without reducing the processing speed.

(Second Embodiment)
FIG. 5 is a cross-sectional view of the immersion objective lens according to the second embodiment of the present invention.

  In the present embodiment, the basic configuration is the same as that of the first embodiment described above, and differences will be mainly described.

  The lens barrel 20 of the immersion objective lens 8 is composed of a metal piece 20a for fixing lens elements at a predetermined interval and a cylindrical member 20b formed so as to cover the outside of the metal piece 20a.

  In the cylindrical member 20b, a pure water supply channel 21 for supplying pure water PW near the focal position of the immersion objective lens 8 so as to be substantially parallel to the optical axis (L1) of the immersion objective lens 8, A pure water recovery flow path 22 for recovering pure water PW from the vicinity of the focal position is formed.

  In the present embodiment, the cylindrical member 20b of the lens barrel 20 is formed of a material having a high transmittance with respect to the light source wavelength. For example, transparent quartz is suitable for 248 nm ultraviolet light. However, the material is not limited to this as long as the material transmits ultraviolet rays.

  An ultraviolet germicidal lamp 40 is disposed on the outer periphery of the cylindrical member 20b of the lens barrel 20. This ultraviolet germicidal lamp 40 has a wavelength having a peak near 260 nm. A plurality of the ultraviolet germicidal lamps 40 may be provided on the outer periphery of the cylindrical member 20b, or may be configured in an annular shape.

  Since the ultraviolet germicidal lamp 40 continues to be lit around the cylindrical member 20b during a series of bright field observations, it prevents bacteria from adhering to the inner walls of the pure water supply / recovery channels 21 and 22 to propagate. it can.

  In addition, during bright field observation, when the light from the ultraviolet germicidal lamp 40 is disturbed by stray light, the light is turned on when the wafer W is not observed, such as during loading / unloading of the wafer W. You can do it.

  As described above, in the present embodiment, the pure water supply / recovery channels 21 and 22 around the immersion objective lens 8 that is most difficult to sterilize can be easily sterilized. Accordingly, particulate contamination caused by microorganisms can be greatly reduced, and the yield of semiconductor devices can be improved.

  Further, since real-time sterilization can be performed during bright-field observation, UV sterilization can always be performed without reducing the processing speed in an apparatus that places importance on throughput, such as the wafer W overview inspection apparatus.

  FIG. 6 is a schematic diagram of a microscope observation apparatus according to a modification of the second embodiment of the present invention.

  The illumination light source 2 is a microscope observation light source including at least a wavelength band of 200 to 300 nm. A part of the ultraviolet light emitted from the illumination light source 2 is separated by a light separation means 41 such as a half mirror or a UV blocking filter and introduced into an optical fiber 42, and the cylindrical member of the barrel 20 of the immersion objective lens 8. 20b around.

  The other end of the optical fiber 42 is connected to an ultraviolet irradiation port 43 (irradiation member), so that the ultraviolet light guided by the optical fiber 42 is purified from the ultraviolet irradiation port 43 through the pure water of the cylindrical member 20b. Irradiates around the supply / recovery channels 21 and 22. Note that a plurality of ultraviolet irradiation ports 43 may be provided on the outer periphery of the cylindrical member 20b, or may be configured in an annular shape.

  The ultraviolet light separated from the illumination light source 2 and introduced into the ultraviolet irradiation port 43 around the cylindrical member 20 b of the lens barrel 20 via the optical fiber 42 is being observed while the wafer W is being observed by the immersion objective lens 8. The lights continue to be lit around the pure water supply / recovery channels 21 and 22. Therefore, it is possible to prevent bacteria from adhering to the inner walls of the pure water supply / recovery flow paths 21 and 22 to propagate.

  Further, during the observation, when the sterilizing ultraviolet light is disturbed by stray light, the time when the wafer W is not observed, such as during loading / unloading of the wafer W, is used. An unillustrated shutter provided at the light source side end may be opened.

  In addition, this invention is not limited to embodiment mentioned above, You may make it the structure which irradiates an ultraviolet-ray only to any one of a pure water supply flow path and a collection | recovery flow path, and can change variously.

1 is a schematic diagram of a microscope observation apparatus according to a first embodiment of the present invention. (A) is sectional drawing of the immersion objective lens shown in FIG. 1, (b) is an arrow line view of the arrow b of (a). (A) is sectional drawing of the immersion objective lens shown in FIG. 1, (b) is an arrow view of the arrow b of (a), (c) is the arrow c of (a). It is an arrow view. (A) is a schematic diagram (drawing along the III-III line of FIG. 1) which shows the switching state of the half mirror and reflection mirror of bright field observation, (b) is the half mirror and reflection of bright field observation. It is a schematic diagram which shows the reflective state of the light of a mirror. It is sectional drawing of the immersion objective lens concerning 2nd Embodiment of this invention. It is a schematic diagram of the microscope observation apparatus which concerns on the modification of 2nd Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Microscope apparatus 2 UV illumination light source 3 Collector lens 4 Aperture stop (AS)
5 Field of view (FS)
6 Condenser Lens 7 Bright Field Half Mirror 8 Immersion Objective Lens 9 Second Objective Lens 10 Bending Mirror 11 Eyepiece 12 CCD
13 XY stage 14 Z stage 15 Wafer holding member 16 Pure water source (pure water production equipment, etc.)
DESCRIPTION OF SYMBOLS 17 Constant discharge pump 18 Vacuum source 19 Wastewater collection tank 20 Lens barrel 20a Hardware 20b Cylindrical member 20c Annular member 21 Pure water supply flow path 22 Pure water recovery flow path 23 Supply pipe 24 Recovery pipe 25 Cover glass (transmission member)
30 Reflective mirror 30a Round hole 30b Mirror surface (reflective part) at the periphery
31 Concave mirror (reflective member)
40 UV germicidal lamp 41 Light separation means 41
42 Optical fiber 43 Ultraviolet irradiation port (irradiation member)

Claims (8)

A pure water supply channel that is provided in the lens barrel of the objective lens and supplies pure water near the focal position of the objective lens;
Provided in the lens barrel, and a pure water recovery flow path for recovering pure water from the vicinity of the focal position;
A light source that emits ultraviolet light;
A microscope observation apparatus comprising: guide means for guiding and irradiating the ultraviolet light from at least the pure light supply flow path from the light source.   The microscope observation apparatus according to claim 1, wherein the guide unit guides and irradiates the ultraviolet light from the light source to the pure water recovery channel. The guiding means includes
Half mirror for bright field observation,
A reflection mirror having an opening in the center and a reflection part in the periphery;
At the time of bright field observation, the ultraviolet light from the light source is reflected by the half mirror for bright field observation and guided to the observation target, while at the time of sterilization, the ultraviolet light from the light source is reflected by the reflection mirror to supply the pure water. The microscope observation apparatus according to claim 1, further comprising: a mirror switching unit that switches the both mirrors so as to guide the flow path or the pure water recovery flow path. The guiding means includes
4. The microscope according to claim 3, further comprising a transmission member that is provided in the barrel and guides the ultraviolet rays reflected by the mirror through the pure water supply channel or the pure water recovery channel. Observation device. The guiding means includes
A reflection member provided at a tip of the lens barrel and configured to reflect ultraviolet rays guided in the pure water supply channel or the pure water recovery channel toward pure water in the vicinity of a focal position of the objective lens; The microscope observation apparatus according to claim 3. The guiding means includes
The microscope observation apparatus according to claim 1, further comprising a transmission lens barrel of an objective lens formed of a material that transmits ultraviolet rays.   The microscope observation apparatus according to claim 6, wherein the light source is arranged around the transmissive barrel. The guiding means includes
An optical fiber for guiding ultraviolet rays from the light source;
An irradiation member that irradiates the ultraviolet light guided by the optical fiber from the periphery of the transmissive lens tube toward the pure water supply flow path or the pure water recovery flow path. The microscope observation apparatus described.

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