Solid immersion lens holder

An arrangement, equipped with a holder 9, which supports a solid immersion lens 3 in the gravity direction with the bottom surface of solid immersion lens 3 being protruded downward through an opening 9b, is provided. With this arrangement, when solid immersion lens 3 is set on an observed object, solid immersion lens 3 is put in a state in which it is raised by the observed object and is made free with respect to holder 9. Also in this state, an excessive pressure will not be applied to the observed object and yet solid immersion lens 3 is put in close contact in conformance with the observed object and temperature drifts at the holder 9 side or the observed object side are cut off from the counterpart side and thus the influences of such temperature drifts are eliminated. A solid immersion lens holder, with which the damaging of the observed object can be eliminated and which enables high-precision observation, is thus provided.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention concerns a holder for a solid immersion lens.

2. Related Background of the Invention

A solid immersion lens (SIL) is known as a lens for magnifying an image of an observed object. This solid immersion lens has a hemispherical shape or a hyperhemispherical shape, called a Weierstrass sphere, and is a microlens with a size of approximately 1 mm to 5 mm. When this solid immersion lens is put in close contact with a surface of an observed object, since both the numerical aperture NA and the magnification are increased, observation at high spatial resolution is enabled.

A device, for which the observed object is a semiconductor wafer and with which a solid immersion lens is put in close contact with a rear surface of the semiconductor wafer to inspect the fine characteristics of the interior of the semiconductor wafer through a microscope, has thus been proposed (see for example, Document 1: Japanese Patent Publication No. H7-18806). A device, for which the observed object is an optical recording medium and with which a solid immersion lens is put in close contact with a rear surface of a transparent substrate of the optical recording medium by being pushed against the rear surface by means of a spring to observe pits, record marks, etc., on the optical recording medium through a microscope, has also been proposed (see for example, Document 2: Japanese Patent Application Laid-Open No. H11-305135).

SUMMARY OF THE INVENTION

Here, though a method of holding a solid immersion lens is not described specifically with the former art, with general methods, for example, a method wherein a solid immersion lens is fixed on a holder by means of an adhesive, etc., or a method wherein a solid immersion lens is held urgingly by a spring as in the latter art, there are the following problems.

That is, there are cases where an observed object with which a solid immersion lens is put in close contact becomes cracked or damaged otherwise due to an excessive pressure being applied to the observed object. In a rear surface analysis of a semiconductor device, the strength during handling must be considered adequately in applying pressure to a semiconductor substrate so that an integrated circuit formed on the semiconductor substrate surface will not become damaged.

Also, since a solid immersion lens is pressed against an observed object, depending on the flatness of the object, observation of high precision is made difficult due to gaps that form between the solid immersion lens and the observed object. With a rear surface analysis of a semiconductor device using a solid immersion lens, when a gap forms between the solid immersion lens and the semiconductor substrate, since incident light of the critical angle or higher becomes totally reflected so that only incident light of no more than the critical angle will propagate, the effective numerical aperture is restricted by the critical angle. However, when the gap between the solid immersion lens and the semiconductor substrate rear surface becomes approximately equivalent to the wavelength of light inside the semiconductor, light is enabled to propagate due to evanescent coupling.

However, if a part at which the gap is large exists in a region in which the bottom surface of the solid immersion lens opposes the rear surface of the semiconductor substrate, the transmitted light intensity drops drastically, only incident light of no more than the critical angle can propagate, and the effective numerical aperture is restricted at this part at which the gap is large. It thus becomes difficult for the inherent resolution of the solid immersion lens to be exhibited.

High precision observation is also made difficult by the peeling off (separation) of a solid immersion lens from an observed object due to a temperature drift at the solid immersion lens holder side or the observed object side.

This invention has been made in view of such issues, and an object thereof is to provide a solid immersion lens holder that enables high precision observation without damaging of an observed object.

A solid immersion lens holder by this invention is characterized in equipping a holder that supports a solid immersion lens in the gravity direction with a bottom surface of the solid immersion lens protruding downward through an opening.

With such a solid immersion lens holder, when the solid immersion lens that is supported in the gravity direction by the holder is set on an observed object, the solid immersion lens is put in a state (free state) in which it is raised by the observed object and is free with respect to the holder. An excessive force will thus not be applied to the observed object and yet the solid immersion lens is put in close contact in conformance (compliance) to the observed object. Also, since a temperature drift at the holder side or the observed object side is cut off with respect to the counterpart side, the influences of temperature drifts are eliminated.

Here, as a specific arrangement by which the above actions are exhibited, an arrangement can be cited wherein the holder is equipped with a first holder, which is formed to have a cylindrical shape, holds the solid immersion lens in a state wherein the bottom surface of the solid immersion lens is protruded downward through an opening at the bottom surface thereof, and is equipped with a collar part at an outer peripheral surface thereof, and a second holder, which is formed to have a cylindrical shape, has the collar part of the first holder set thereon in a state wherein the bottom surface of the solid immersion lens, held by the first holder, is protruded downward through an opening at the bottom surface thereof, and supports the first holder and solid immersion lens in the gravity direction.

With such a solid immersion lens holder, the solid immersion lens can be held by the first holder without having to perform special processing on the solid immersion lens, and since the self-weights of the first holder and the solid immersion lens act on the observed object, an excessive pressure will not be applied to the observed object.

Also, as another specific arrangement that effectively exhibits the above-described actions, an arrangement can be cited wherein the solid immersion lens is arranged so that a central part of a bottom surface thereof protrudes with respect to a peripheral edge part thereof and the holder is formed to have a cylindrical shape, has the peripheral edge part of the solid immersion lens set thereon in a state wherein the central part of the solid immersion lens is protruded downward through an opening at the bottom surface thereof, and supports the solid immersion lens in the gravity direction.

With such a solid immersion lens holder, only the self-weight of the solid immersion lens acts on the observed object and the application of an excessive pressure to the observed object is prevented further.

The holder that supports the solid immersion lens is preferably equipped with a cylindrical cap, which is fitted onto an opening at an upper part of the holder and is for preventing the falling-off of the solid immersion lens. In this case, the falling-off of the solid immersion lens through the upper opening of the abovementioned holder is prevented by the above-described cap.

Also preferably, an arm part, which extends outward from the holder that supports the solid immersion lens, is equipped and this arm part is connected to a three-dimensional direction moving device. In this case, the solid immersion lens is freely moved to a desired position in three-dimensional directions by using the moving device.

The arm part may also be detachably connected to the three-dimensional direction moving device. In this case, for lens exchange, exchange of the arm part as a whole is enabled and the lens exchange is facilitated due to not having to handle the minute solid immersion lens.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Preferred embodiments of this invention's solid immersion lens holder shall now be described with reference toFIG. 1toFIG. 24.FIG. 1is a block diagram showing a semiconductor inspection device equipped with a solid immersion lens holder of a first embodiment of this invention,FIG. 2toFIG. 4are respectively perspective views showing a solid immersion lens moving device and an objective lens,FIG. 5toFIG. 7are respectively diagrams of states illustrating moving operations of the solid immersion lens moving device,FIG. 8toFIG. 10are respectively diagrams showing the solid immersion lens holder, FIG.11toFIG. 13are respectively perspective views showing a part at which the solid immersion lens holder and the solid immersion lens moving device are connected,FIG. 14toFIG. 16are respectively diagrams showing an optical coupling material supplying means and a drying gas supplying means,FIG. 17is a vertical section showing a solid immersion lens holder of a second embodiment of this invention,FIG. 18andFIG. 19are respectively diagrams showing a solid immersion lens holder of a third embodiment of this invention,FIG. 20toFIG. 22are respectively diagrams showing a solid immersion lens holder of a fourth embodiment of this invention, andFIGS. 23 and 24are respectively diagrams showing another solid immersion lens holder. In the respective figures, the same elements shall be provided with the same symbols and redundant description shall be omitted. This invention's solid immersion lens holder is generally applicable to sample observation methods and microscopes, etc., that use a solid immersion lens. However, in the following description, examples of application to semiconductor inspection shall mainly be described.

First, the semiconductor inspection device equipped with the solid immersion lens holder of the first embodiment shall be described. As shown in FIG.1, semiconductor inspection device1is an inspection device, for which the object of observation is a semiconductor device S, wherein a circuit pattern, for example, of a transistor and wiring, etc., is formed, and images of this semiconductor device S are acquired for inspection of the internal information thereof. With this invention, “internal information” shall include circuit patterns of semiconductor devices as well as emission of weak light from semiconductor devices. Such weak light emissions include those caused by an abnormal position due to a defect of a semiconductor device, transient light emission that accompanies the switching operation of a transistor inside a semiconductor device, etc. The generation of heat due to a defect of a semiconductor device is also included.

This semiconductor inspection device1is equipped with an observation part A for performing observation of semiconductor device S, a control part B for controlling the operations of the respective parts of observation part A, and an analysis part C for performing the processing, instructing, etc., necessary for the inspection of semiconductor device S. Semiconductor device S is set, with its rear surface facing upward, on a stage18, provided at observation part A, and in the present embodiment, inspection device1is used to inspect the lower surface in the figure of semiconductor device S (integrated circuits, etc., formed on a substrate surface of semiconductor device S).

Observation part A is equipped with a high-sensitivity camera10and a laser scanning microscope (LSM) unit12, which are image acquisition means for acquiring images from semiconductor device S, an optical system2, which includes an objective lens20of a microscope4that is positioned between semiconductor device S and high-sensitivity camera10and LSM unit12, a solid immersion lens3, for obtaining magnified observation images of semiconductor device S, a solid immersion lens manipulator30, which is a solid immersion lens moving device that moves solid immersion lens3in three-dimensional directions, and an X-Y-Z stage15, which moves the above-mentioned components respectively in orthogonal X, Y, and Z directions.

In addition to the abovementioned objective lens20, optical system2is equipped with a camera optical system22and an LSM unit optical system24. A plurality of objective lenses20of different magnifications are provided in a switchable manner. Camera optical system22guides light from semiconductor device S that has passed through an objective lens20to high-sensitivity camera10, and high-sensitivity camera10thereby acquires an image of a circuit pattern, etc., of semiconductor device S. Meanwhile, LSM unit optical system24guides infrared laser light from LSM unit12to semiconductor device S by reflecting the light to the objective lens20side by means of a beam splitter (not shown) and branches, by means of the beam splitter, a part of reflected light from semiconductor device S that is directed towards high-sensitivity camera10via objective lens20and guides this light to LSM unit12.

This LSM unit12scans an infrared laser light in the X-Y directions and emits this light towards the semiconductor device S side and detects the reflected light from semiconductor device S by means of a photodetector (not shown). The intensity of this detected light will be an intensity that reflects the circuit pattern of semiconductor device S. Thus by X-Y scanning of semiconductor device S by infrared laser light, LSM unit12acquires an image of the circuit pattern, etc., of semiconductor device S.

X-Y-Z stage15is for moving high-sensitivity camera10, LSM unit12, optical system2, solid immersion lens3, solid immersion lens manipulator30, etc., as necessary in each of the X-Y directions (horizontal directions; directions parallel to semiconductor device S, which is the observed object) and the Z direction (vertical direction) orthogonal to the X-Y directions.

Solid immersion lens3is a microlens having a hemispherical shape (seeFIG. 9) or a hyperhemispherical shape, called a Weierstrass sphere, of a size of approximately 1 mm to 5 mm. By the bottom surface of this solid immersion lens3coming into close contact with an observation position (the illustrated upper surface) for observing semiconductor device S, a magnified observation image of the surface (the illustrated lower surface) of semiconductor device S at the rear side is obtained.

Specifically, a solid immersion lens that is used in a semiconductor inspection device is formed of a high refractive index material that is practically the same or close to the substrate material of the semiconductor device in refractive index. Representative examples of this material include Si, GaP, GaAs, etc.

By putting such a microscopic optical element into close optical contact with a substrate surface of a semiconductor device, the semiconductor substrate itself can be put to use as a part of the solid immersion lens. In rear surface analysis of a semiconductor device using a solid immersion lens, in setting the focal point of an objective lens to an integrated circuit formed on a surface of a semiconductor substrate, the effect of the solid immersion lens enables the focal point position to be set so as not to be as deep as that in air. Light flux of high NA can thus be made to pass through the substrate and the achievement of high resolution by use of short wavelengths can be anticipated.

The lens shape of such a solid immersion lens3is determined by conditions with which aberrations are eliminated. With a solid immersion lens having a hemispherical shape, the sphere center thereof becomes the focal point. In this case, both the numerical aperture NA and the magnification are multiplied by n. On the other hand, with a solid immersion lens with a hyperhemispherical shape, the focal point is located at a position shifted downward by R/n from the sphere center. In this case, both the numerical aperture NA and the magnification are multiplied by n2. Solid immersion lens3of conditions besides the above, such as that with which the focal point is positioned between the sphere center and the position shifted downward by R/n from the sphere center, etc., may be used in accordance with the specific observation conditions, etc., for semiconductor device S.

Solid immersion lens holder5(seeFIG. 8toFIG. 10) is for favorably supporting solid immersion lens3. Also, solid immersion lens manipulator30(seeFIG. 2toFIG. 7), which moves this solid immersion lens holder5in three-dimensional directions, is for moving solid immersion lens3, which is supported by solid immersion lens holder5, to the respective predetermined positions of: an inserted position, which is a position between semiconductor device S and objective lens20and includes an optical axis from semiconductor device S to objective lens20; a closely contacting position, at which the bottom surface of solid immersion lens3is put in close contact with an observation position of semiconductor device S; a standby position, which lies outside the above-mentioned optical axis; an exchange position for exchanging solid immersion lens3, etc. This solid immersion lens holder5and solid immersion lens manipulator30shall described in detail later.

Control part B is equipped with a camera controller51a, a laser scan (LSM) controller51b, a stage controller52, and a manipulator controller53. Camera controller51aand LSM controller51bcontrol the operations of high-sensitivity camera10and LSM unit12, respectively, and thereby control the execution of the observation of (acquisition of images from) semiconductor device S, which is carried out in observation part A, as well as the setting of the observation conditions, etc.

Stage controller52controls the operation of X-Y-Z stage15and thereby controls the movement, positioning, focusing, etc., of high sensitivity camera10, LSM unit12, optical system2, etc., to positions corresponding to the observation position of semiconductor device S. Manipulator controller53controls the operation of solid immersion lens manipulator30and thereby controls movements of solid immersion lens3to the abovementioned predetermined positions as well as fine adjustment of the closely contacting position of solid immersion lens3, etc. (details shall be provided later).

Analysis part C is equipped with an image analysis part61and an instructing part62and is arranged from a computer. Image analysis part61performs the necessary analysis processes, etc., on image information from camera controller51aand laser scan controller51b. Instructing part62references the contents input by an operator, the contents of analysis by image analysis part61, etc., and provides the necessary instructions concerning the execution of inspection of semiconductor device S at observation part A, via the control part B. The image, data, etc., that have been acquired or analyzed at analysis part C are displayed as necessary on a display device63, connected to analysis part C.

Solid immersion lens holder5and solid immersion lens manipulator30, which make up the characteristics of the present embodiment, shall now be described in detail.

As shown inFIG. 8andFIG. 9, solid immersion lens holder5is equipped with a holder6, which is formed to a substantially cylindrical form and supports solid immersion lens3, and an arm part7, which holds this holder6. Since this solid immersion lens holder5comes in contact with an optical contact liquid to be described below in some cases, it is formed, for example, of stainless steel, aluminum, or other metal of high corrosion resistance or of a resin, such as acrylic resin, PET, polyethylene, polycarbonate, etc., which can be formed readily in accordance with the shape of the solid immersion lens.

As shown inFIG. 9, holder6is equipped with a first holder8, which holds solid immersion lens3, and a second holder9, which supports this first holder8. This first holder8and second holder9are formed to a substantially cylindrical form so as not to obstruct the optical path with respect to semiconductor device S.

First holder8is equipped on the outer peripheral surface of an upper part thereof with an annular collar part8a, which protrudes outwards, and is equipped on the bottom surface with an annular collar part8b, which is directed inwards, and solid immersion lens3is held by being fixed, for example, by an adhesive agent, etc., to first holder8in a state in which the bottom surface of solid immersion lens3protrudes downward through an opening formed at the inner periphery of annular collar part8b.

Second holder9is equipped at its bottom surface with an inwardly directed annular collar part9a. Annular collar part8aof first holder8is set on annular collar part9aof second holder9and first holder8and solid immersion lens3are supported in the gravity direction by second holder9in a state wherein a lower part of first holder8is protruded downward through an opening9b, formed at the inner part of annular collar part9a.

Here, if the outer diameter of the lower part of first holder8is A, the outer diameter of annular collar part8aof first holder8is B, and the inner diameter of opening9bof second holder9is C, these are set to satisfy the relationship, A<C<B. First holder8is made free with respect to second holder9and yet the falling-off of first holder8downwards from second holder9is prevented.

Second holder9is also equipped at an opening9cat an upper part thereof with a cap11, which is mounted by fitting, screwing, etc., and is for preventing the falling off of the solid immersion lens. As with first holder8and second holder9, this cap11is formed to a substantially cylindrical form, and if the inner diameter of cap11is D, it is set to satisfy the relationship, D<B. Thus by means of cap11, separation, such as the springing out of first holder8, which holds solid immersion lens3, through opening9cat the upper part of second holder9, is thus prevented and the loss of the solid immersion lens is prevented without obstruction of the optical path for semiconductor device S.

Also, arm part7is arranged by bending a round bar to a substantially L-like shape and extends outward from second holder9with one end thereof being directed upwards and the other end thereof being fixed to a side part of second holder9. As shown inFIG. 8andFIG. 9, a rotation stopping part7a, with which a part of a side face of a pipe is made a flat surface, is fixed, for example, by fitting, etc., onto one end of arm part7as a rotation stop for arm part7and holder6. Though arm part7is arranged to be substantially L-like in shape and has one end thereof extending upward, it may be arranged to extend within the X-Y plane instead.

As shown inFIG. 11, arm part7, which makes up this solid immersion lens holder5, is detachably connected to one end of a first arm member71of solid immersion lens manipulator30. As shown inFIG. 12andFIG. 13, connecting part99, which connects this first arm member71with solid immersion lens holder5, is equipped at first arm member71with a through hole71a, through which rotation stopping part7aof arm part7can be inserted in the vertical direction, and a fastening part71b, which has its front end face formed to a flat surface and which narrows or spreads through hole71aby being screwed forward or backward (advancing or retreating).

In this arrangement, rotation stopping part7a, which has been inserted in through hole71a, is fixed to first arm member71by advancing fastening part71bby turning it in the fastening direction. In this state, the flat surface of rotation stopping part7aof arm part7is made to contact and then put in close contact with the flat surface at the front end of fastening part71b, thereby arranging a rotation stop for arm part7and solid immersion lens holder5. Also, arm part7, which has thus been fixed to first arm member71, can be released and extracted from first arm member71, for example, for exchange of solid immersion lens3, etc., by retreating fastening part71bby rotating it in the opposite direction.

Solid immersion lens manipulator30, which holds solid immersion lens holder5by means of this connecting part99, freely moves solid immersion lens3in solid immersion lens holder5to the respective abovementioned predetermined positions (inserted position, closely contacting position, standby position, and exchange position) in three-dimensional directions as shown inFIG. 1toFIG. 7. As shown inFIG. 2toFIG. 7, this solid immersion lens manipulator30is equipped with the above-described first arm member71, to which solid immersion lens holder5is mounted, a first arm member rotation source72, which rotates this first arm member71within the X-Y plane, a second arm member73, which holds this first arm member rotation source72, a second arm member rotation source74, which rotates this second arm member73within the X-Y plane, and a Z-direction movement source75, which moves this second arm member rotation source74in the Z-direction that is orthogonal to the X-Y plane, and this Z-direction movement source75is deemed to be at the base end side and the moving first arm member71is deemed to be the terminal end side.

Specifically, Z-direction movement source75is arranged from a Z-axis motor, etc., with which a movement shaft75ais moved in the Z-direction, for example, by a feeding screw, etc., and is mounted to microscope4as the main device body side via a supporting part76. This supporting part76is detachably mounted to microscope4, for example, by being screwed on, etc., so as to be convenient, for example, for carrying out microscopic observation upon removing solid immersion lens manipulator30or carrying out microscopic observation upon mounting another lens moving device.

Second arm member rotation source74is connected via a supporting part77to movement shaft75aof Z-direction movement source75. This second arm member rotation source74is arranged from a motor, etc., with which the output shaft is, for example, a rotation axis74a, which rotates in the forward and reverse directions (needs only to rotate within a predetermined range), and is moved in the Z-direction by the driving of Z-direction movement source75.

One end of second arm member73is connected to this rotation axis74aof second arm member rotation source74. Though details shall be given later, this second arm member73is arranged in a curving manner so that second arm member73can be moved away readily from the field of view of the observation position of semiconductor device S (field of view of objective lens20) as shown inFIG. 6.

First arm member rotation source72is fixed to the other end of second arm member73as shown inFIG. 2toFIG. 7. This first arm member rotation source72is arranged from a motor, etc., with which the output shaft is, for example, a rotation axis72a, which rotates in the forward and reverse directions (needs only to rotate within a predetermined range). Rotation axis72aof first arm member rotation source72and rotation axis74aof second arm member rotation source74are thus positioned non-coaxially. By the driving of second arm member rotation source74, first arm member rotation source72is rotated along with second arm member73within the X-Y plane and with rotation axis74aof second arm member rotation source74as the supporting point.

The other end of the above-described first arm member71is connected to rotation axis72aof first arm member rotation source72. This first arm member71is rotated within the X-Y plane and with rotation axis72aof first arm member rotation source72as the supporting point by the driving of first arm member rotation source72.

Thus by the driving of first arm member rotation source72and second arm member rotation source74, solid immersion lens3, supported by solid immersion lens holder5connected to one end of first arm member71, is moved in synthetic directions, resulting from the synthesis of the respective rotations, within the X-Y plane, is also moved in the Z-direction by the driving of Z-direction movement source75, and is consequently moved freely to the respective predetermined positions in three-dimensional directions.

Furthermore, solid immersion lens manipulator30of this embodiment is used for obtaining a magnified observation image by means of solid immersion lens3, and, as shown inFIG. 14, is equipped with an optical coupling material supplying means80, which supplies an optical coupling material for optically coupling solid immersion lens3to the observation position of semiconductor device S, and a drying gas supplying means90, which supplies a gas for drying this optical coupling material.

When an optical coupling material is interposed between a solid immersion lens and an observed object and light of the critical angle or more with respect to the contact surface of the solid immersion lens and the observed object is made to propagate inside the solid immersion lens, a light flux of high numerical aperture (NA) can be passed through and thus the inherent resolution of the solid immersion lens can be exhibited.

Optical coupling material supplying means80supplies an optical contact liquid (comprising, for example, water and a surfactant), which contains, for example, amphiphilic molecules, to the observation position of semiconductor device S immediately prior to bringing solid immersion lens3into close contact with the observation position. With this optical coupling material supplying means80, an optical contact liquid is contained inside a compact dedicated liquid tank81, which has a volume, for example, of 1 cc and is fixed to supporting part76as shown inFIG. 14andFIG. 15. The contained optical contact liquid is then put in a pressurized state by means of a compressed gas, such as compressed air, etc., and by supplying a pulse signal from a control system83to a microvalve82, which, for example, is a solenoid valve that is equipped with a spring, is fixed to supporting part76, and is connected to the exit of liquid tank81, the optical contact liquid is sprayed from a supply port85aat the tip of an optical coupling material supply pipe85, which is connected to microvalve82via a flexible pipe84and is fixed to first arm member71as shown inFIG. 2toFIG. 7.

Since the optical contact liquid, which contains amphiphilic molecules, is low in surface tension, it spreads across the semiconductor substrate, which is a hydrophobic surface. In the process of drying this optical contact liquid, forces that tend to maintain the wettability of the surface of the semiconductor substrate and the bottom surface of the solid immersion lens become dominant. The vaporization of mainly the water of the optical contact liquid thus progresses while the surface interval between the bottom surface of the solid immersion lens and the semiconductor substrate surface narrows. In the final stage, the solid immersion lens and the semiconductor substrate become optically coupled.

It is considered that in this state, van der Waals forces act between water molecules and the hydrophilic groups of the amphiphilic molecules, which have become physically adsorbed onto the semiconductor substrate surface and the bottom surface of the solid immersion lens, and due to the binding of water molecules, the vaporization thereof is stopped. The distance between the solid immersion lens and the semiconductor substrate at this point can be made, for example, 1/20λ (λ: illumination wavelength) or less, and as a result, evanescent coupling as well as physical fixation of the solid immersion lens and the semiconductor substrate are achieved. “Optical contact” in this invention shall refer to a state wherein optical coupling is achieved by evanescent coupling.

As an optical coupling material besides the above-described optical contact liquid, a refractive index matching fluid (index matching liquid, etc.), such as that described in Japanese Patent Publication No. H7-18806 and with which refractive index matching of a solid immersion lens and a semiconductor substrate is achieved, can be cited. In the present Specification, a refractive index matching fluid differs from an optical contact liquid, and whereas the former realizes a high NA by means of the refractive index of a fluid, the latter has a role of aiding evanescent coupling. Though an embodiment using an optical contact liquid shall be described in detail here, the same effects can be realized with an embodiment using a refractive index matching fluid. However, in such a case, since the fluid does not have to be dried necessarily, an embodiment is possible wherein drying gas supplying means90is omitted.

This optical coupling material supply pipe85is fixed to first arm member71and supply port85aat the front end thereof is set near solid immersion lens holder5as shown inFIG. 2toFIG. 7. The pipe thus moves along with solid immersion lens3and is enabled to spray the optical contact liquid towards the targeted observation position. This optical contact liquid is controlled in sprayed amount by control of the duration during which the pulse signal is on and is sprayed from supply port85aat a precision of the picoliter level. The sprayed amount of optical contact liquid is determined suitably in accordance with the size of solid immersion lens3. Also, this optical contact liquid is preferably exchanged as suited in order to prevent decomposition, change of concentration, and clogging by the liquid.

In place of microvalve82, an optical coupling material supplying means may be used wherein a tubing type microdispenser is used and, without pressurizing liquid tank81by compressed gas, the tube of the tubing type microdispenser is mechanically squeezed to make the optical contact liquid inside liquid tank81drip towards the observation position from supply port85aat the front end of optical coupling material supply pipe85via flexible pipe84. In this case, the capacity of liquid tank81is set to a few dozen cc's and the dripping amount is determined as suited according to the size of solid immersion lens3.

Drying gas supplying means90supplies a gas for rapidly drying the optical contact liquid between the observation position of semiconductor device S and solid immersion lens3. As shown inFIG. 14andFIG. 16, with this drying gas supplying means90, ON/OFF signals are supplied from a control system93to a solenoid valve92, fixed to support part76, to make a gas, such as compressed dried air, nitrogen gas, etc., be blown out from a supply port95aat the tip of a gas supply pipe95, which is connected to solenoid valve92via a flexible pipe94and is fixed to first arm member71as shown inFIG. 2toFIG. 7.

As with optical coupling material supply pipe85, drying gas supply pipe95is fixed to first arm member71and supply port95aat the front end thereof is set near solid immersion lens holder5as shown inFIG. 2toFIG. 7. The pipe thus moves along with solid immersion lens3and is enabled to blow gas towards the targeted position between the observation position of the semiconductor device and solid immersion lens3.

The actions of semiconductor inspection device1, having the above-described arrangement, shall now be described. The description shall start from the state, shown inFIG. 5, wherein solid immersion lens3is positioned at the standby position. At this standby position, first and second arm members71and73are folded and solid immersion lens3and first and second arm members71and73are set outside the view field of objective lens20. At this point, first holder8, holding solid immersion lens3, has its annular collar part8aset on annular collar part9aof second holder9and first holder8and solid immersion lens3are supported in the gravity direction by second holder9as shown inFIG. 9. In this standby state, a pattern image, which is a normal observation image of the observation position of semiconductor device S is acquired and then, for example, a voltage is applied, etc., to semiconductor device S and the image in this process is acquired.

Here, if there is an abnormal position in semiconductor device S, an emission image will be obtained, and the abnormal position of semiconductor device S can thus be specified by overlapping the normal observation image with the image obtained when a voltage was applied. In the case where there is an abnormal position, high-sensitivity camera10, LSM unit12, optical system2, solid immersion lens holder5, solid immersion lens manipulator30are moved by means of X-Y-Z stage15so that objective lens20will be positioned coaxial to the abnormal position.

Solid immersion lens3is then set with respect to the observation position of semiconductor device S. In this case, firstly, first and second arm member rotation sources72and74of solid immersion lens manipulator30are driven and by thus rotating first and second arm members71and73, solid immersion lens3, at the standby position, is moved to the inserted position, between semiconductor device S and objective lens20and containing the optical axis from semiconductor device S to objective lens20as shown inFIG. 3,FIG. 4andFIG. 6. Here, since second arm member73is formed to have a curved shape, second arm member73is kept readily away from the view field without obstructing the view field of objective lens20as shown inFIG. 6.

When solid immersion lens3has thus been inserted at the inserted position, Z-direction movement source75of solid immersion lens manipulator30is driven to lower solid immersion lens3. When solid immersion lens3then approaches the observation position, optical contact liquid is supplied to the observation position, which is the targeted position, from optical coupling material supplying means80and solid immersion lens3is set on the observation position and positioned at the closely contacting position.

When solid immersion lens3is thus set on the observation position of semiconductor device S, solid immersion lens3and first holder8, which are supported in the gravity direction by second holder9, are raised by semiconductor device S as shown inFIG. 10.

Fine adjustment of the closely contacting position of solid immersion lens3is then carried out. This fine adjustment is carried out by minutely moving solid immersion lens holder5in the Z-direction by the driving of Z-direction movement source75of solid immersion lens manipulator30and minutely swinging first arm member71by means of first arm member rotation source72and these are carried out so that first holder8, holding solid immersion lens3, will be spaced apart in the X-Y-Z directions from second holder9and thus will not contact second holder9. Specifically, an image containing reflected light from solid immersion lens3is acquired, and the reflected light from the reflecting surfaces of various parts of solid immersion lens3in the reflected light image, contained in the abovementioned image, are used as guides.

More specifically, analysis is performed automatically or based on instructions from an operator on the acquired image by means of image analysis part61of analysis part C to determine the position of the center of gravity of the reflected light image. Then by means of instructing part62of analysis part C, solid immersion lens manipulator30is instructed via manipulator controller53to perform fine adjustment of the closely contacting position of solid immersion lens3so that the center of gravity position of the reflected light image obtained at image analysis part61matches the observation position at semiconductor device S. The positioning of solid immersion lens3with respect to the observation position of semiconductor device S and objective lens20is thus carried out.

Since solid immersion lens3and first holder8are put in a free state with respect to second holder9in a state in which they are raised by semiconductor device S, only the self-weights of solid immersion lens3and first holder8act on the observation position of semiconductor device S and thus the application of an excessive force is eliminated and yet solid immersion lens3is put in close contact in conformance (compliance) to the observation position.

Gas is then supplied by means of drying gas supplying means90to the region at which solid immersion lens3contacts the observation position, which is the targeted position, and by thus drying the optical contact liquid, solid immersion lens3is rapidly put into definite, close contact with the observation position of semiconductor device S. Since solid immersion lens3is thus put into definite, close contact with the observation position of semiconductor device S by means of the optical contact liquid from optical coupling material supplying means80, high-precision observation is enabled, and since the drying of the optical contact liquid is promoted by the gas from drying gas supplying means90, immediate execution of observation is enabled.

When close contact of solid immersion lens3with the observation position is thus achieved, adjustment of the distance between semiconductor device S on and with which solid immersion lens3is set and put in close contact, and objective lens20, is instructed from instructing part62to X-Y-Z stage15via stage controller52to perform focusing. In this process, since solid immersion lens manipulator30and solid immersion lens3move in the Z-direction along with objective lens20, solid immersion lens3is made to move in the opposite Z-direction by means of solid immersion lens manipulator30so as to maintain the close contact of solid immersion lens3with the observation position. A magnified observation image of the observation position is then acquired via optical system2, which includes objective lens20and solid immersion lens3that is put in close contact with the observation position of semiconductor device S, and high resolution observation is carried out.

During this observation, since solid immersion lens3and first holder8are put in a free state with respect to second holder9as described above, temperature drifts at the second holder9side or the semiconductor device S side are cut off with respect to the counterpart side and the influences of these temperature drifts are thus eliminated.

For observation of the next observation position, the optical contact liquid is supplied again from optical coupling material supplying means80. The close contact of solid immersion lens3with the observation position is thereby released, and thereafter, solid immersion lens holder5is moved by solid immersion lens manipulator30by the reverse procedures as the procedures described above to move solid immersion lens3to the standby position shown inFIG. 5. Subsequently, the same procedures as those described above are repeated.

In place of the optical contact liquid, the solvent thereof may be used to release the optical contact. The optical contact is released by wetting the contacting portion with the optical contact liquid or the solvent thereof since the optical contact liquid or solvent thereof reenters into the boundary surface between the solid immersion lens and the semiconductor device and destroys the optically coupled state and the physically fixed state. By this method, the solid immersion lens and the semiconductor device can be separated without applying an excessive force. Since the semiconductor device and the solid immersion lens will thus not become flawed, the solid immersion lens can be reused.

Here, if the need to exchange solid immersion lens3arises, first arm member rotation source72of solid immersion lens manipulator30is driven to rotate first arm member71to move solid immersion lens3from the standby position shown inFIG. 5, at which connecting part99is positioned close to a lower part of second arm member73and is difficult to handle, to the lens exchange position shown inFIG. 2andFIG. 7. Connecting part99is moved outward greatly from near the lower part of second arm member73and solid immersion lens holder5is exchanged together with arm part7. Since connecting part99is set at a handling position in the process of lens exchange, the detachment and attachment of arm part7of solid immersion lens holder5with respect to first arm member71is facilitated, and since solid immersion lens holder5is exchanged along with arm part7, the minute solid immersion lens3does not have to be handled and the exchange of the lens is thus facilitated.

Thus with solid immersion lens holder5of the present embodiment, only the self-weights of solid immersion lens3and first holder8act on the observation position of semiconductor device S and the application of an excessive pressure is thus eliminated. Damaging of semiconductor device S can thus be prevented. Also, solid immersion lens3is put in close contact in conformance (compliance) with the observation position and yet temperature drifts at the second holder9side or the semiconductor device S side are cut off from the counterpart side and thus the influences of such temperature drifts are eliminated. High-precision observation is thus enabled without peeling off of solid immersion lens3from the observation position.

Also, with solid immersion lens manipulator30of the present embodiment, solid immersion lens3is moved to predetermined positions within the X-Y plane by rotation of first and second arm members71and73. There is thus no need to make the component parts long in the orthogonal X and Y directions, and a simple arrangement that occupies a small area is provided. Compactness of the device can thus be realized while realizing low cost.

Also, with semiconductor inspection device1, equipped with this solid immersion lens manipulator30, when both an observation image, which is taken in the normal state in which solid immersion lens30is not set between semiconductor device S and objective lens20, and a magnified observation image, which is taken in the state in which solid immersion lens3is inserted, are to be acquired, these images can be acquired readily. Also, in this case, since high resolution observation is carried out by the magnified observation image, inspection using semiconductor inspection device1can be carried out readily and with high precision.

FIG. 17is a vertical section showing a solid immersion lens holder of a second embodiment of this invention in the state in which a lens is set at a standby position. This solid immersion lens holder54of the second embodiment differs from solid immersion lens holder5of the first embodiment in that a first holder55, with which an annular step part8cis formed in connection to the inner side of the lower surface of a collar part8a, is used in place of first holder8, and a holder56is arranged from this first holder55and second holder9. The outer diameter of this annular step part8cof first holder55is made slightly smaller than the inner diameter of opening9bof second holder9.

Needless to say, even with the present arrangement, the same effects as those of the first embodiment can be obtained. In addition, since the spacing (spacing in the X-Y directions) between first holder55and second holder9is made minute by the provision of annular step part8c, the merit that it suffices to perform fine adjustment of the close contact position of solid immersion lens3just in the Z-direction by means of solid immersion lens manipulator30is provided.

FIG. 18is a perspective view showing a solid immersion lens holder of a third embodiment of this invention, andFIG. 19is a vertical section showing the solid immersion lens holder in the state in which a lens is set at a closely contacting position. Solid immersion lens holder57of this third embodiment differs from solid immersion lens holder5of the first embodiment mainly in that a solid immersion lens13that differs in shape from solid immersion lens3is used, and accordingly, a single holder58is used in place of first and second holders8,9to support solid immersion lens13.

As shown inFIG. 19, solid immersion lens13is arranged to have a shape wherein a central part13aof the bottom surface thereof protrudes downward with respect to a peripheral part13bthereof.

Holder58is formed to a substantially cylindrical form and is equipped with an annular collar part58a, which is directed inwards, at the bottom surface thereof. Peripheral part13bof solid immersion lens13is set on annular collar part58aof holder58in the state in which the bottom surface of the protruding central part13aof solid immersion lens13protrudes downward from an opening58bformed in the inner part of annular collar part58a, and solid immersion lens13is thereby supported in the gravity direction by holder58.

Here, if the outer diameter of central part13aof solid immersion lens13is E, the outer diameter of peripheral part13bof solid immersion lens13is F, and the inner diameter of opening58bof holder58is G, these are set to satisfy the relationship E<G<F. Solid immersion lens13is thus made free with respect to holder58and yet the falling-off of solid immersion lens13downward from holder58is prevented.

Also, by means of a substantially cylindrical cap59, which is mounted, for example, by fitting, screwing, etc., onto an opening58cat an upper part of holder58, the falling-off of solid immersion lens13from holder58is prevented without obstructing the optical path with respect to semiconductor device S.

Needless to say, even with the present arrangement, the same effects as those of the first embodiment can be obtained. In addition, though processing is required of solid immersion lens13, in comparison to the first embodiment wherein the self-weights of solid immersion lens3and first holder8act, since only the weight of solid immersion lens13acts on semiconductor device S, the merit that it is even more unlikely for an excessive pressure to be applied to semiconductor device S is provided.

FIG. 20is a perspective view showing a solid immersion lens holder of a fourth embodiment of this invention, andFIG. 21is a vertical section showing the solid immersion lens holder in the state in which a lens is set at a closely contacting position. Also,FIG. 22is a perspective view showing a part at which the solid immersion lens holder and a solid immersion lens moving device are connected. As shown inFIG. 20andFIG. 21, solid immersion lens holder105is equipped with a holder106formed to a substantially cylindrical form, which supports solid immersion lens103, and an arm part107, which holds this holder106.

As shown inFIG. 21, holder106is equipped with a lower holder108and an upper holder109. Of these, upper holder109is arranged as an annular part that is formed integral to arm part107. Lower holder108, for supporting solid immersion lens103, is supported by arm part107via this upper holder109. These holders108and109are formed to substantially cylindrical forms so as not to obstruct the optical path with respect to semiconductor device S.

As with solid immersion lens13shown inFIG. 19, solid immersion lens103is arranged to have a shape wherein a central part103aof the bottom surface thereof protrudes downward with respect to a peripheral part103bthereof. With the present embodiment, the outer peripheral surface of the protruding central part103ahas a tapered shape that decreases in outer diameter towards the lower side.

Holder108is formed to a substantially cylindrical form and is equipped with an annular collar part108a, which is directed inwards, at the bottom surface thereof. Peripheral part103bof solid immersion lens103is set on annular collar part108aof holder108in the state in which the bottom surface of the protruding central part103aof solid immersion lens103protrudes downward from an opening108bformed in the inner periphery of annular collar part108a, and solid immersion lens103is thereby supported in the gravity direction by holder108. The outer and inner diameters of the respective parts are set in the same manner as the embodiment illustrated inFIG. 18and FIG.19.

Also, a cap111is provided above holders108and109. By this cap111, the falling-off of solid immersion lens103from holders108and109is prevented without obstruction of the optical path with respect to semiconductor device S. Cap111of the present embodiment has an annular form and has an arrangement having a plurality of claw parts (three claw parts in the figure) that protrude towards the inner side.

Also, arm part107is formed of a plate-like member that extends outward from upper holder109, with one end thereof being directed obliquely upward and the other end thereof being integrated with upper holder109as mentioned above. As shown inFIG. 20andFIG. 21, a rotation stopping part107a, which extends vertically upwards and with which a part of its side face is made a flat surface, is fixed to the one end of arm part107as a rotation stop for arm part107and holder106.

As shown inFIG. 22, arm part107, which makes up solid immersion lens holder105, is connected to one end of first arm member71of solid immersion lens manipulator30. Furthermore with the present embodiment, first arm part71of solid immersion lens manipulator30is arranged to be detachably attachable to first arm member rotation source72. In the arrangement example shown inFIG. 22, first arm member71is detachably connected to rotation axis72aof first arm member rotation source72by means of a hexagon socket head bolt72b.

Needless to say, even with the present arrangement, the same effects as those of the first embodiment can be obtained. In addition, though processing is required of solid immersion lens103, since only the self-weight of solid immersion lens103acts on semiconductor device S, the merit that it is even more unlikely for an excessive pressure to be applied to semiconductor device S is provided.

Also, with the above-described embodiment, first arm member71, to which solid immersion lens holder105is connected, is arranged to be detachably mounted to first arm member rotation source72. By thus making first arm member rotation source72, of comparatively high rigidity, an attachable/detachable part, the occurrence of deformation of first arm member71or arm part107of solid immersion lens holder105is prevented and these members are thus improved in durability. Also in performing observation of a sample by means of solid immersion lens103, the parallelism of the observed object and solid immersion lens103can be maintained favorably.

Also with an arrangement wherein first arm member71is mounted to first arm member rotation source72by means of a bolt, etc., as shown inFIG. 22, the attachment/detachment work can by performed using a hexagonal wrench or other tool. The handling of the device, for example, in exchanging solid immersion lens103along with first arm member71and solid immersion lens holder105, etc., is thus facilitated.

Also with the above-described embodiment, a part of holder106is arranged from upper holder109, which is an annular part that is integral to arm part107. The rigidity of solid immersion lens holder105can thereby be improved. Also, the positioning of the arm part and the annular holder part of the solid immersion lens holder (especially the positioning in the rotation direction) is made unnecessary. With such an arrangement, the entirety of holder106may be arranged from an annular part that is integral to arm part107.

Also, arm part107is made to have a shape that extends obliquely upward from holder106. Since space at the side of solid immersion lens103can thus be secured, observation of a sample can be carried out favorably. For example, in a case of inspecting a plastic molded type IC, since steps are formed at the surroundings of inspected positions due to mold cutting, the range in which the solid immersion lens holder can be moved is restricted. However, with the above arrangement wherein arm part107is made oblique, interference between the steps of the observed object and the arm part of the solid immersion lens holder can be lessened and observation of the observed object using the solid immersion lens can thus be carried out favorably.

With solid immersion lens holder105of the above-described arrangement, lower holder108, having annular collar part108a, may be made of the same or a similar material as that of upper holder109and arm part107or may be formed by processing a water absorbing structure, such as a water absorbing ceramic. By applying a water absorbing structure to the holder, the merit that, when an excessive amount of optical contact liquid is applied, the time for drying the liquid and bringing the solid immersion lens and the observed object into close contact optically can be shortened is provided.

FIG. 23is a perspective view showing another solid immersion lens holder, andFIG. 24is a vertical section showing this other solid immersion lens holder in the state wherein a lens is positioned at a closely contacting position. With this solid immersion lens holder64, holder65, which makes up solid immersion lens holder64, is formed to have a cylindrical form and the inner diameter thereof is made large in comparison to the outer diameter of solid immersion lens3. Solid immersion lens3is positioned in the inner part of holder65with the bottom surface of this solid immersion lens3protruding from an opening at the bottom surface of holder65.

With such a solid immersion lens holder64, solid immersion lens3is moved to a desired observation position by being moved in a sliding manner across semiconductor device S while being hitched onto the inner peripheral surface of holder65of solid immersion lens holder64, which moves within the X-Y plane. Solid immersion lens holder64is then moved in the Z-direction and then solid immersion lens holder64is furthermore moved within the X-Y plane, thus leaving solid immersion lens3on the observation position of semiconductor device S while solid immersion lens holder64is moved away from solid immersion lens3. The merit that observation can be carried out upon moving all components away from the view field of the observation position of semiconductor device S is thereby provided.

Though the present invention has been described specifically based on the embodiments above, this invention is not limited to the above-described embodiments, and various modifications are possible. For example, though with the above-described embodiments, holders9and58for supporting solid immersion lenses3and13are formed to have cylindrical forms as especially preferable forms, these holders may instead be flat plates equipped with openings9band58b.

Also with the above-described embodiments, solid immersion lens manipulator30is enabled to move solid immersion lens3or13in the Z-direction to thereby enable solid immersion lens3or13to be moved freely to desired positions in three-dimensional directions by a simple arrangement. However, z-direction movement source75may be eliminated so that the lens manipulator is enabled to move only within the X-Y plane and movement in the Z-direction may be accomplished by means of X-Y-Z stage15, or stage18, on which semiconductor device S is set, may be enabled to move in the Z-direction. In such cases, the position at which solid immersion lens3or13is inserted by solid immersion lens manipulator30is deemed to be the closely contacting position. Also, solid immersion lens manipulator30, which is a three-dimensional direction moving device, is not limited to a rotational type wherein two arm members71and73are rotated within the X-Y plane but may instead be a known X-Y-Z direction moving device that moves in the orthogonal X-Y-Z directions.

Also, though with the above-described embodiments, a semiconductor device, formed of a semiconductor substrate, is used as an example of the observed object, this invention is not limited thereto, and the observed object may be an electronic device with, for example, a glass or plastic substrate. In this case, glass or plastic is preferably used as the material of the solid immersion lens.

Specifically, though with the above-described embodiments, the observed sample is a semiconductor device, generally when semiconductor devices and various other types of electronic devices are used as samples, the device to be observed is not limited to that which uses a semiconductor substrate, and the observed object may be an integrated circuit, such as a polysilicon thin film transistor that has glass or plastic, etc., as the substrate. For example, with a liquid crystal device, the device is prepared on a glass substrate, and with an organic EL, the device is prepared on a plastic substrate. As even more general samples, biological samples using prepared slides, etc., can be cited in addition to the abovementioned semiconductor devices, liquid crystal devices, and various other types of devices.

Also, though with each of the above-described embodiments, application to inspection device1for semiconductor device S is described as an especially effective application, this invention is not limited thereto and may be applied, for example, to an optical observation device, etc., for performing inspection of an optical recording medium as an observed object, as described in Japanese Patent Application Laid-Open No. H11-305135.

Also, though with each of the above-described embodiments, a predetermined position of the lower surface of the observed object (surface of semiconductor device S) is observed and solid immersion lens3or13is used so that the focal point is set at a predetermined position of the lower surface of the observed object, this invention is not limited thereto, and in cases where the interior or upper surface of an observed object is to be observed, a solid immersion lens may be used to set the focal point in the interior or at the upper surface of the observed object as described, for example, in Japanese Patent Application Laid-Open No. 2001-189359.

With each of the above-described solid immersion lens holders, since excessive pressure will not be applied to the observed object, the damaging of the observed object can be prevented. Also, since the solid immersion lens is put in close contact in conformance (compliance) with the observed object and yet temperature drifts at the holder side or the observed object side are cut off from the counterpart side and thus the influences of such temperature drifts are eliminated, high-precision observation is enabled.