JPH04343003A - Detecting apparatus of fluorescence of semiconductor/ mask - Google Patents

Abstract

PURPOSE:To obtain the maximum detecting sensitivity of fluorescence by selecting an illuminating means in accordance with the shape, kind or the like of a foreign substance, adjusting the illuminating angle, direction or the like of an excitation light, and setting the wavelength of the excitation light and fluorescent light to be optimum. CONSTITUTION:Since there is a direction easy to detect at the remaining resist on a sample 11 according to the shape of the pattern or the other condition, the most effective one of the excitation light sources 1a-1c to detect fluorescence is selected by an instruction from a computer 60 as the output level of an image element 45 of a display 62 is monitored. The illuminating angle of each of the optical fibers 30a, 30c, etc., is set in accordance with the instructing value of the computer 60 by 70a, 70c mounted at an opening part of a casing 50 of this fluorescence detecting device. Further, the computer 60 sets the wavelength of each variable filter 110-112 at the side of the excitation light to be an initial value, and then scans the wavelength of a variable filter 120 at the detecting side, thereby to detect the wavelength when the intensity of fluorescence becomes maximum and set the filter 120 at the detected wavelength.

Description

[Detailed description of the invention]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inspection apparatus for semiconductor wafers and masks, and more particularly to a fluorescence detection apparatus for detecting fluorescence emitted by minute resist residues on wafers and masks with high sensitivity and high speed.

0001

2. Description of the Related Art Conventionally, resist residue on the surface of a semiconductor wafer has been inspected using a scanning electron microscope, a fluorescence microscope, or the like. Figure 2 is “L” edited by the Institute of Electronics and Communication Engineers published in 1981
SI Handbook”, page 689 is a block diagram of a fluorescence analysis system.

In FIG. 2, when observing resist residue, which is organic foreign matter, on a sample 11, ultraviolet light from an excitation light source 1 is directed to the sample through a filter 2, a beam splitter 4, an objective lens 5, etc. The sample 11 is irradiated perpendicularly to the surface of the sample 11, and the fluorescence emitted by the organic foreign matter on the sample 11 is extracted through the objective lens 5, beam splitter 4, monochromator 7, etc. and detected by the detector 7. was. In addition, when identifying organic foreign substances, use a monochromator 7.
The above fluorescence spectrum analysis was carried out using the following method. In addition, when observing the pattern on the surface of the sample 11,
The mirror 12 was tilted to the position indicated by the dotted line so that the observation light 3 was irradiated onto the surface of the sample 11.

Japanese Patent Laid-Open No. 2-115752 discloses a detection system that irradiates the wafer surface with oblique laser light and detects foreign matter from the scattered light, and a detection system that irradiates the wafer surface with oblique laser light and detects foreign matter from the scattered light, and a detection system that irradiates the wafer surface with UV excitation light such as a mercury lamp. It has been disclosed that an analysis system for analyzing the properties of foreign substances based on the wavelength, color information, etc. of fluorescence obtained by perpendicular irradiation to the wafer can be carried out consistently without moving the wafer. Furthermore, Japanese Patent Application Laid-open No. 1-191044 describes an inspection system that detects the position, shape, etc. of foreign objects by irradiating S-polarized laser beams for low-angle irradiation and high-angle irradiation obliquely onto the wafer surface. ,
An epi-fluorescence microscope system that detects the nature of foreign substances from the fluorescence obtained by vertically irradiating the wafer surface with excitation light in the UV, B, and BV regions such as a mercury lamp can be housed in a single inspection device. Disclosed.

Furthermore, Japanese Patent Application Laid-Open No. 1-102342 discloses that a laser beam is introduced from below the sample parallel to the optical axis of a fluorescence microscope and scanned two-dimensionally to determine the wavelength of fluorescence emitted by the sample. It has been disclosed that different intensities are measured and subjected to arithmetic processing to create two-dimensional or three-dimensional images.

[0005]

[Problems to be Solved by the Invention] When inspecting the wafer surface using the scanning electron microscope described above, although the surface can be observed in detail, only the remaining resist on the surface is highlighted and the wiring pattern, diffusion layer, etc. Since it is not possible to clearly distinguish and display the images, there is a problem in that inspection of the obtained images requires skill and time. Furthermore, there is also the problem that the inspection throughput is extremely low because the inside of the microscope must be evacuated prior to inspection.

[0006] Furthermore, when using the above fluorescence microscope,
Due to the lack of resolution, fluorescence detection sensitivity, etc., there has been a problem in that resist residues in the submicron region of recent microfabricated ICs, LSIs, etc. cannot be inspected. Also,
In the fluorescence analysis system shown in Figure 2 above, there is a problem in that it is difficult to determine in advance the optimal excitation conditions to increase the sensitivity of fluorescence detection because the surface condition of each wafer is different, and organic foreign substances that cannot be detected in practice remain. Therefore, IC, LS
The performance was insufficient for inspection of resist residue in the submicron region such as I.

[0007] Also, the above-mentioned Japanese Patent Application Laid-Open Nos. 2-115752, 1-191044, and 1-1023
In Publication No. 42 and the like, since UV excitation light from a mercury lamp or the like is perpendicularly irradiated onto the wafer surface, there is a problem in that foreign matter present in various shapes on the wafer surface cannot necessarily be efficiently excited. The purpose of the present invention is to improve the fluorescence detection sensitivity by adjusting the irradiation angle, direction, etc. of the excitation light according to the shape, type, etc. of the foreign object, and to improve the fluorescence detection sensitivity by optimally setting the wavelength of the excitation light and fluorescence. An object of the present invention is to provide a semiconductor/mask fluorescence detection device that can obtain a fluorescence detection sensitivity of .

[0008]

[Means for solving the problem] The excitation light is irradiated obliquely to the wafer, mask, etc. (sample), and is irradiated from the entire circumference of the sample, and the irradiation angle and direction are different. An irradiation means effective for fluorescence detection is selected from among a plurality of excitation light irradiation means, and further,
A means for irradiating excitation light perpendicularly to the sample surface is also provided.

Furthermore, means for changing the irradiation angle of the excitation light is provided, for example, an optical fiber that introduces the excitation light into the fluorescence detection device, and one end of the optical fiber that is connected to the interior of the fluorescence detection device housing. The optical fiber device is constructed by means that can penetrate through the optical fiber device and hold it therein, and further adjust the installation angle, installation position, etc. of the optical fiber device.

Furthermore, the wavelength of the excitation light and the detection wavelength of the fluorescence can be changed, so that the maximum value of the fluorescence that changes depending on the irradiation angle, the wavelength of the excitation light, the detection wavelength of the fluorescence, etc. is detected. Furthermore, the optimal conditions such as the irradiation angle, excitation light wavelength, and fluorescence detection wavelength corresponding to the maximum value of fluorescence are displayed, and the multiple optimal conditions obtained for the same resist material (foreign substance) are statistically processed. and calculate its most probable value.

[0011] Furthermore, the excitation light is polarized and irradiated, and the fluorescence of the sample is detected through a polarizing plate. Further, the excitation light is intermittently irradiated and the fluorescence obtained after the excitation light is shut off is detected. Furthermore, visible light is also irradiated onto the sample surface, so that the pattern image of the sample obtained by visible light irradiation and the fluorescence image obtained by excitation light irradiation are superimposed and displayed.

0012

[Action] By irradiating the excitation light obliquely and adjusting the irradiation angle, the fluorescence intensity can be increased, and by vertical irradiation of the excitation light, foreign substances present at the bottom of the trench of the sample can be detected. . Furthermore, the maximum fluorescence intensity can be obtained by adjusting the wavelength of the excitation light and the detection wavelength of fluorescence. Furthermore, by statistically processing and displaying the conditions under which the maximum intensity of fluorescence can be obtained, it is possible to replace the filters on the excitation light side and the fluorescence side with more suitable ones.

Furthermore, by polarizing the excitation light and detecting the fluorescence of the sample through a polarizing plate, background noise is reduced and the S/N of fluorescence detection is improved. Furthermore, by detecting the fluorescence after irradiation with the excitation light, the influence of background noise due to diffuse reflection of the excitation light can be removed. Furthermore, by superimposing and displaying the sample pattern image obtained by visible light irradiation and the fluorescence image obtained by excitation light irradiation, the position of the foreign object can be correlated with the pattern position. will be displayed.

[0014]

[Examples] Next, the present invention will be explained in detail with reference to Examples. [Embodiment 1] FIG. 1 is a configuration diagram of an excitation light irradiation section in an embodiment of a fluorescence detection apparatus according to the present invention. Excitation light source 1
The amount of the emitted light is adjusted by a diaphragm (diaphragm) 22, the wavelength region is set by an excitation light filter inserted into the excitation filter insertion port 21, and the light is input into the optical fiber 30. The optical fiber 30 is inserted into the interior of the fluorescence detection device through the opening of the housing 50 and irradiates the sample 11 with excitation light. Reference numeral 51 denotes a shield that prevents scattered light from the surface of the sample 11 from entering through the sides of the absorption filter 42 and the like. Cover 5
1 can be omitted by shielding the side portions of the absorption filter 42 and image intensifier 40 from light.

The remaining resist on the sample 11 emits fluorescence due to the irradiation with the excitation light, and this is sent to the image intensifier 4 through the objective lens 5, absorption filter 42, etc.
0. The absorption filter 42 and the like block the excitation light and allow only fluorescence to pass through. FIG. 3 is a configuration diagram of the image intensifier 40. As shown in FIG. The photocathode 47 of the image intensifier 40 converts the incident fluorescence into electrons, which enter the microchannel electron multiplier 46 .

For example, as shown in FIG. 4, the microchannel electron multiplier 46 has a cross-sectional structure in which microchannels 421 made of a large number of small-diameter silica glass tubes are bundled, and each microchannel 421 is an electron multiplier tube. It works as. That is, as shown in FIG. 5, each time the primary electrons incident from the bottom of the microchannel 421 collide with the inner wall of the silica glass tube, they are multiplied by secondary electron emission, so one primary electron becomes, for example, 1 million. It is multiplied and emitted. This electron multiplication factor can be adjusted by applying a bias voltage.

The electrons emitted from the microchannel electron multiplier 46 are converted into light by an anode phosphor 43 shown in FIG. Although the brightness of this light image has been significantly enhanced, its shape is the same as that of the fluorescent image incident on the photocathode 47. The emitted light image of the anode phosphor 43 is formed by a lens 44 on the light receiving surface of an image sensor 45 and converted into an electrical signal.

The first feature of the fluorescence detection apparatus of the present invention is that, as shown in FIG. 1, the surface of the sample 11 is irradiated with excitation light obliquely. That is, Figure 2
When the excitation light is irradiated perpendicularly to the surface of the sample 11 as in the conventional device, a strong scattered light component from the surface of the sample 11 directly enters the objective lens 5 and is filtered through the absorption filter 42.
Therefore, the background noise of the image signal output from the image sensor 45 increases.

In contrast, in the present invention, since the excitation light is obliquely irradiated onto the surface of the sample 11 through the optical fiber 30, the excitation light component directly reflected from the sample surface can be weakened. Furthermore, since the actual resist residue tends to adhere to the pattern on the sample surface and the sidewalls of the uneven parts, the above-mentioned oblique irradiation can increase the amount of excitation light irradiated to the resist residue, thereby increasing the output image signal intensity. , the detection sensitivity of resist residue can be increased.

Table 1 shows experimental data showing the effect of oblique irradiation according to the present invention.

[Table 1] In Table 1, the tip of the optical fiber 30 is placed approximately 30 mm away from the excitation light irradiation position of the sample 11 as shown in FIG. Measured using a counter. As samples 11, sample 1 with a large number of dot-like resist patterns as shown in FIG. 7 and sample 2 with a large number of band-like resist patterns as shown in FIG. 7 were prepared. The excitation light was irradiated onto one of the six resist pattern areas. In addition, a xenon lamp that can obtain relatively uniform intensity over a wide wavelength range is used as the excitation light source 1, and the excitation filter has a wavelength range of 380 to 425 nm.
The low cutoff wavelength of the absorption filter 42 was set to 450 nm.

As shown in Table 1, the count value of the photon counter changes significantly depending on the incident angle θ of the excitation light, and both samples 1 and 2 have the maximum count value at the incident angle θ=15 degrees. It shows. Furthermore, considering that the above-mentioned count value rapidly attenuates as the incident angle θ increases to 20 degrees and 25 degrees, it can be seen that the oblique incident It can be seen that the fluorescence detection sensitivity is significantly improved in some cases. In other words, the oblique incidence of the present invention can significantly increase fluorescence detection sensitivity.

FIG. 9 shows a sample 11 provided with a plurality of linear resists having different line widths in order to examine the ability of the present invention apparatus to detect remaining resist. It measures the count value of . This shows that a resist line width of 0.5 μm can be detected with sufficient accuracy, and even narrower line widths can also be detected. Next, in order to confirm the resist remaining detectability value obtained in FIG. 9, minute resist remaining on an actual wafer was investigated. First, using a scanning microscope, a sample with a diameter of approximately 0.2μ was placed on the wafer.
It was confirmed that there was a resist residue of 0.5 μm in size, and then excitation light was obliquely incident on the fluorescence detection device of the present invention to detect fluorescence from the confirmed resist residue. As a result, a fluorescent image having the same shape as the two remaining resists could be detected very clearly. Therefore, from this experimental result, it can be estimated that the fluorescence detection device of the present invention can sufficiently detect resist residues having diameters, widths, etc. of 0.1 μm or less.

[0023] Since there are a wide variety of resist materials used for semiconductor wafers, the above-mentioned incident angle θ, type of excitation light source 1, passage wavelength range of the excitation filter, low cutoff wavelength of the absorption filter, etc. depend on the type of resist material. It is necessary to reset the settings accordingly.

[Example 2] In the above Example 1, the excitation light was irradiated obliquely to the sample 11 from one direction. However, when irradiating in only one direction, the resist facing in that direction looks good, but the resist facing in other directions does not always look good. This problem can be solved by irradiating the sample 11 with excitation light from all around the sample 11 as shown in FIG.

In FIG. 10, reference numeral 31 denotes a light guide that bends the direction of the excitation light introduced by the optical fiber 30 toward the sample 11 and irradiates the objective lens 5 from the entire circumference. As a result, the excitation light is emitted in the direction shown by the dotted line, so that the part immediately below the objective lens 5 on the sample 11 can be irradiated over the entire circumference. Note that a filter 32 may be attached to the lower part of the light guide 31 if necessary. Furthermore, the direction of emission of the excitation light can be adjusted as appropriate by changing the way the light guide 31 is made.

[Embodiment 3] In recent semiconductor memories, a trench structure as shown in FIG. 11 is increasingly being adopted in order to increase the charge storage capacity without increasing the space. In such a trench structure, it is necessary to be able to reliably detect the resist residue 13 at the bottom of the trench in addition to the resist residue 12 at the surface. However, although the resist residue 12 on the surface portion can be well detected by the method described in Examples 1 and 2 of the present invention, it is difficult to detect the resist residue 13 because the obliquely irradiated excitation light does not reach the resist residue 13.

In such a case, as shown in FIG.
An optical fiber 33 is provided, and its excitation light is sent to a half mirror 34.
It is reflected by the beam and irradiated perpendicularly to the surface of the sample 11 through the objective lens 5, so that the resist residue 13 can be reliably detected. Note that, if necessary, the excitation light sources connected to the optical fibers 31 and 33 are switched.

[Example 4] Fluorescence emitted by the remaining resist is due to the energy generated when an aromatic hydrocarbon material having a conjugated double bond in the resist material transitions to an excited state by ultraviolet irradiation and then returns to the ground state. Occurs due to difference. Therefore, if the excitation light is allowed to pass through the resist residue as long as possible, the amount of fluorescence increases in proportion to the length of passage, so that the detection sensitivity of the resist residue can be improved.

For this purpose, the incident angle θ is set so that the excitation light passes through the resist residue 12 while repeating total reflection, as shown in FIG. The above-mentioned total reflection is more likely to occur when the incident angle θ is set to an angle of several degrees as shown in FIG. 13, and the flatter the remaining resist, the more the number of total reflections. Furthermore, since the excitation light component emitted from the resist remains is substantially perpendicular to the optical axis direction of the fluorescence microscope, the rate at which this light component enters the fluorescence microscope as background noise is also significantly reduced. However, the actual shape of the remaining resist varies, and setting the incident angle θ to the above several degrees does not always result in the best fluorescence detection sensitivity. It is important to be able to search for the angle at which the best fluorescence detection sensitivity can be obtained by varying the value within a range of several tens of degrees as shown in Table 1.

[Example 5] In FIG. 12, when visible light is made incident on the optical fiber 33, the pattern on the sample surface changes.
Statues can be inspected. Furthermore, by superimposing the image of the resist residue obtained by irradiating the excitation light from the optical fiber 30 on the visible light pattern image, it is possible to grasp the positional relationship between the pattern on the sample and the resist residue. ,
Failure analysis can be made even more convenient. FIG. 14 is a block diagram of an embodiment of the present invention that can display the pattern image and the residual resist image in a superimposed manner.

In FIG. 14, 1a is an excitation light source, and 1b is a light source that can switch between excitation light and visible light. first,
Computer 60 sends a command signal to drive device 63 to set sample 11 on scanning stage 10 at a predetermined position. Next, the light source 1b is turned on to irradiate the sample 11 with visible light to detect a pattern image. This pattern image is displayed on display 6.
2, the image is confirmed and stored in the image memory 61. Next, the light source is switched from 1b to 1a, and the sample 11 is irradiated with excitation light to detect a resist residual image and similarly store it in the image memory 61. If the sample has a trench structure, the light source 1b is switched to ultraviolet light so that the sample 11 is irradiated with excitation light perpendicularly.

The operator calls up the pattern image, resist residual image, etc. from the image memory 61, superimposes both images as necessary, and displays them on the display 62 to inspect the sample. In FIG. 14, a ring-shaped light guide 3
1 is used to irradiate a predetermined portion of the sample 11 from all around the circumference, but depending on the situation, the light guide 31 may be omitted and irradiation may be performed as shown in FIG.

[Example 5] As is well known, there are a wide variety of types of resist materials used in the manufacture of semiconductor devices, and the value of the optimum wavelength of the excitation light to be irradiated onto the sample 11 differs depending on the type. . Therefore, in order to perform the best inspection, it is necessary to select the optimal wavelength of the excitation light. For such purposes, an excitation light source with variable wavelength is required. As such a wavelength-tunable excitation light source, for example, a xenon lamp that can provide excitation light with uniform intensity over a relatively wide wavelength range is combined with a rotary continuous spectral filter, or an ultraviolet dye laser (dye laser) is used.
er) etc.

A dye laser is a laser that strongly optically excites a dilute solution or vapor of an organic dye and oscillates by stimulated emission of its fluorescence transition. The fluorescence spectrum of dyes has a wide linewidth, so if you insert a diffraction grating into the laser resonator, you can obtain monochromatic laser oscillation with a variable wavelength. Its wavelength can be varied over a period of time. Recently, for example, the wavelength has been changed to 5 nm.
There are products on the market that can be changed in steps.

In FIG. 14, excitation light source 1a and light source 1
If the dye laser device described above is used for either or both of b, and the wavelength is controlled by the computer 60, the wavelength at which the clearest image can be obtained is searched for while monitoring the display 62, and the wavelength at that wavelength is controlled. Images can be stored. 15 and 16 are data examples showing the relationship between the wavelength of the excitation light and the corresponding fluorescence detection sensitivity.

A characteristic line 101 in FIG. 15 is the measurement result of the fluorescence intensity at a wavelength of 510 nm obtained when a positive resist material is irradiated with excitation light varying in wavelength from 310 to 460 nm. From this, the wavelength of the excitation light is 380
It can be seen that the detection sensitivity for fluorescence with a wavelength of 510 nm can be maximized by setting the wavelength to 510 nm. In order to confirm this result, the characteristic line 102 is the fluorescence intensity measurement result when the excitation light wavelength was fixed at 380 nm and the fluorescence wavelength was varied, and the fluorescence detection sensitivity is maximum at a wavelength of 510 nm.

FIG. 16 shows similar measurement results for i-line resist material. It can be seen from the characteristic line 103 that the excitation light wavelength that maximizes the fluorescence intensity at a wavelength of 450 nm is 390 nm. Furthermore, it can be seen from the characteristic line 104 that fluorescence having a wavelength of 450 nm is detected with maximum sensitivity with respect to the excitation light of 390 nm. The wavelength value at which the fluorescence intensity is maximum is approximately specified by the type of resist material, so by specifying the excitation light wavelength as described above, it is possible to specify the excitation filter on the excitation light source side. The work time involved in selecting an excitation filter can be significantly reduced. Note that such automatic selection of the excitation light wavelength and excitation filter will be explained in Example 8, which will be described later.

[Embodiment 6] When detecting fluorescence by irradiating the sample 11 with ultraviolet light, an ultraviolet light component is mixed into the fluorescence as background noise, reducing the S/N of the detection signal. Particularly when the fluorescence intensity is weak, the background noise becomes a major obstacle in improving detection accuracy. A pulse excitation method is known as a countermeasure for such cases, and this method can also be applied to the present invention.

FIG. 17 is a diagram illustrating the temporal change in fluorescence emitted by an organic sample such as a resin in the pulse excitation method described above. When the sample 11 is irradiated with ultraviolet light from time T1 to T2, the fluorescence intensity after T2 attenuates as shown in the figure, and its lifetime (time constant of decay) is about 10~9 to 10~6 seconds. In the present invention, the ultraviolet light sources 1a and 1b in FIG. 14 are pulse-lit as described above, and a fluorescent image is detected during the lifetime after the lights are turned off to obtain a fluorescent image free of the background noise. Make it. Further, this method is suitable when a laser suitable for pulse excitation is used as the ultraviolet light source of the ultraviolet light source 1a and the light source 1b.

[Embodiment 7] By changing the attachment angle of the optical fiber 30 in FIG. 1, the irradiation angle of the ultraviolet light onto the sample 11 can be changed. Since the irradiation angle has an optimum value depending on the resist material to be detected and the shape of the wafer surface, a means for quickly and easily changing the irradiation angle is required. Furthermore, as is clear from FIG. 1, changing the installation angle of the optical fiber 30 also changes the irradiation position of the ultraviolet light hitting the sample 11.
I want to be able to change only the angle while keeping the irradiation position fixed. However, since the irradiation size of the ultraviolet light (excitation light) on the sample surface is usually about 10 to 20 mmφ, there is little practical problem even if the irradiation position is slightly shifted by changing the irradiation angle.

FIG. 18 is a sectional view of an embodiment of the excitation light angle adjusting device according to the present invention. In FIG. 18, the rack 73 of the angle adjustment device 70 is fixed to the opening of the casing 50 of the fluorescence detection device. Further, the optical fiber 30 is attached to a gear 71 so that it can rotate. Gear 71 is gear 7
At the same time, the pinion 74 is also driven by the motor 72 via a gear 75. The rotating shafts of gear 71, gear 75, motor 72, pinion 74, etc. are fixedly supported by plate 76, and plate 76 is guided by guide groove 77 and pin 78, so that, for example, motor 72 is , the optical fiber 30 rotates as shown by arrow B, and the plate 76 moves in the direction of arrow C. Therefore, by appropriately setting the rotation transmission ratio of gears 75 and 71 and the rotation transmission ratio of gear 75 and pinion 74, the optical fiber 30 can be moved vertically as it rotates, and The irradiation position of ultraviolet light can be fixed. When initially setting the irradiation angle, for example, the gear 75 and pinion 74 are uncoupled, only the gear 71 is rotated to direct the optical fiber 30 to a predetermined position on the sample, and then the gear 75 and pinion 74 are rotated. Try to combine them.

FIG. 19 is a cross-sectional view of an embodiment of the present invention in which a similar angle adjustment device is provided to the full-circle irradiation type light guide 31 shown in FIG. 10, and only the left half of the light guide 31 is shown. In FIG. 19, a rack 73 is fixed to an opening in a casing 50 of the fluorescence detection device, and the light guide 31 can rotate around a fulcrum 77. Also, motor
The rotating shafts of the rotor 72, gear 75, pinion 74, etc. are fixed to a plate 76, and the plate 76 is movable in the vertical direction along the rack 73. When the motor 72 rotates in the direction of the arrow, the rotation is transmitted to the gear 75 and pinion 74 to move the plate 76 upward. This movement causes the plate 76
pushes up the light guide 31, so the light guide 31
rotates around the fulcrum 77 to move the direction of the excitation light downward. In this way, the irradiation angle of the excitation light can be changed while the irradiation position of the excitation light is fixed.

FIG. 20 is a perspective view of the light guide section shown in FIG. 19 above. Since the light guide 31 is divided in the circumferential direction, its mounting angle can be changed in accordance with the movement of the plate 76. Further, the optical fibers 30 are distributed and coupled to each of the divided light guides.

[Embodiment 8] FIG. 21 is a configuration diagram of a fluorescence detection apparatus of the present invention that can automatically optimally set the irradiation angle adjustment and wavelength setting of excitation light, the detection wavelength of fluorescence, etc. In Figure 21, multiple ultraviolet light sources are used;
The light guides shown in 9 and 20 can also be used. In FIG. 21, each excitation light source and fluorescence detection unit includes a rotary continuous spectral filter 110 as a variable filter,
111, 112, etc. are attached so that their respective passing wavelengths can be set by command signals from the computer 60. Although a plurality of the excitation light sources are provided as necessary, only 1a and 1c are representatively depicted in the figure.

Furthermore, the optical fibers 30a and 30c are attached to the opening of the fluorescence detection device housing 50 by angle adjustment devices 70a and 70c, respectively, and their respective irradiation angles are set by command values from the computer 60. be done. The above-described configuration allows optimal fluorescence testing conditions to be set accurately and quickly, and its features will be sequentially explained below.

1) Since the remaining resist on the wafer has a direction that is easy to detect depending on the pattern shape and other conditions, the computer 60 monitors the image on the display 62 and the output level of the image sensor 45. By selecting a plurality of excitation light sources, the most effective excitation light source for fluorescence detection can be selected.

2) By scanning the irradiation angle of the angle adjustment device of each excitation light source using the computer 60, the optimum irradiation angle of each angle adjustment device can be automatically set.

3) The fluorescence detection sensitivity can be maximized by automatically setting each of the excitation light sources and fluorescence wavelengths optimally. FIG. 22 is an example of fluorescence intensity spectrum characteristics of various foreign substances. In this way, in addition to the resist residue described above, the wafer has fibers from the clothes of the worker, fine skin tissue, etc. attached to the wafer, and the optimum fluorescence wavelength etc. for each are different. Further, the optimum fluorescence wavelength for each resist material generally differs as shown in FIG. 23.

The computer 60 first sets the wavelengths of the variable filters 110 to 112 on the excitation light side to initial values, and then scans the wavelengths of the variable filter 120 on the fluorescence detection side to find the wavelength at which the fluorescence intensity is maximum. The wavelength is detected and the variable filter 120 is set to that wavelength. The above measurement is repeated while shifting the wavelength of each of the variable filters 110 to 112 on the excitation light side by a predetermined width from the above initial value, and each variable filter 110 to 112 on the excitation light side from which the maximum fluorescence intensity is obtained is The wavelengths of the variable filter 120 on the fluorescence detection side are determined and the final fluorescence measurement is performed at those wavelengths.

Further, since the approximate excitation wavelength and fluorescence wavelength for resist and other foreign matter are usually known, these values are stored in advance in the computer 60, and the type of resist or foreign matter is designated. Each variable filter 110 to 112 on the excitation light side and the variable filter 12 on the fluorescence detection side
After initially setting the wavelength of 0 to the above-mentioned stored value, the wavelength of the variable filter 120 on the fluorescence detection side is scanned and set to the optimum value, and then each of the variable filters 110 to 1 on the excitation light side is scanned.
Similarly, wavelengths such as 12 are scanned and set to the optimum value. With the fluorescence detection of the present invention, it is possible to significantly shorten the time required to determine the filters for the excitation light side and the fluorescence detection side, which was a huge amount of time in conventional devices.

4) Chips on a wafer can be sequentially and automatically inspected. Computer 60 is connected to scanning stage 1
Since the feeding and positioning of chips on the wafer (sample 11) is performed by controlling All chips on the sample 11 can be automatically inspected in a continuous and continuous manner.

5) By displaying each irradiation angle, wavelength, etc. obtained as described above, it is possible to improve the S/N of fluorescence detection by employing more suitable filters. Moreover, the above-mentioned displayed value can be used as a reference for the next inspection. In general, the pass characteristics of variable filters are looser than those of fixed band filters, so the variable filters 110 to 112, 12
After detecting the optimal wavelength for the excitation light side and the fluorescence detection side using 0, replacing each variable filter with another more suitable fixed bandpass filter can limit unnecessary bandwidth, which can reduce the S/N of fluorescence detection. can be improved.

For this reason, the values of each optimum irradiation angle, each optimum wavelength, etc. are displayed on the display 62. Further, in addition to the average values of each optimum irradiation angle, each optimum wavelength, etc., the standard deviations calculated by the computer 60 are also displayed on the display. Since the standard deviation value is an index representing the degree of dispersion, the operator can use this value to determine the bandwidth of the fixed filter to be replaced.

[Example 9] In each of the above embodiments of the present invention, the excitation light is S or P polarized and irradiated onto the sample 11, and a polarizing plate corresponding to the polarized light is inserted on the fluorescence detection side. , the S/N of fluorescence detection can be improved. That is, since the polarized excitation light component scattered from the sample 11 can be blocked by the polarizing plate on the fluorescence detection side, the background noise can be reduced and fluorescence can be detected.

[0055]

[Effects of the Invention] Since the fluorescence detection device of the present invention irradiates the sample surface with excitation light obliquely, background noise such as the excitation light component directly reflected from the sample surface is reduced.
The output image signal S
/N can be increased.

Furthermore, by irradiating the excitation light with S or P polarization and inserting a polarizing plate corresponding to the above polarization on the fluorescence detection side, background noise such as the excitation light component scattered from the sample surface can be suppressed. can be reduced. Furthermore, since the fluorescence emitted by the sample is greatly multiplied by the image intensifier, weak fluorescence images can be detected. Furthermore, by irradiating the excitation light obliquely from the entire circumference of the sample, the detection rate of resist residue can be increased.

Furthermore, since the irradiation angle of the excitation light can be controlled and the optimum irradiation angle can be detected quickly, the best residual resist detection rate can be obtained for each resist material and surface condition of the sample. . Further, by selecting the optimum wavelength of the excitation light using, for example, a variable wavelength excitation light source that is a combination of a dye laser or a xenon lamp and a rotating continuous spectral filter, it is possible to increase the detection rate of resist residue.

Furthermore, by providing an excitation light source that irradiates the sample surface vertically in addition to the above-described oblique irradiation of the excitation light, it is possible to reliably detect resist residue attached to the bottom of a trench in a semiconductor memory or the like. Further, by polarizing the excitation light into S or P polarization and providing a polarizing plate corresponding to the polarization on the fluorescence detection side, fluorescence with less background noise can be detected. Further, by selecting the optimum wavelength of the excitation light using, for example, a variable wavelength excitation light source that is a combination of a dye laser or a xenon lamp and a rotary continuous spectral filter, it is possible to increase the detection rate of resist residue.

Furthermore, by irradiating the sample surface with visible light perpendicularly, the pattern image on the sample surface can be detected, and at the same time, the resist remaining image can be displayed superimposed on the pattern image. The failure location of the IC can be easily identified. Furthermore, the most effective excitation light source for fluorescence detection is set by controlling the lighting and irradiation angle of multiple excitation light sources.
In addition, the excitation light and fluorescence wavelengths are selected using variable filters, and the optimal fluorescence detection conditions are automatically set and displayed for each type of resist and foreign material, so each chip within the wafer is automatically and continuously detected. Can be inspected. In addition, by lighting the excitation light source in pulses and detecting the fluorescent image during the lifetime after irradiation, it is possible to detect the fluorescent image without background noise and increase the S/N, so it is possible to detect the fluorescent image without background noise. Extremely advantageous for discovery and identification.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram of an embodiment of an excitation light oblique irradiation device in a fluorescence detection device of the present invention.

FIG. 2 is a configuration diagram of a conventional fluorescence detection device.

FIG. 3 is a configuration diagram of an image intensifier in the fluorescence detection device of the present invention.

FIG. 4 is a perspective cross-sectional view of an image intensifier used in the fluorescence detection device of the present invention.

FIG. 5 is an explanatory diagram of the operation of an image intensifier used in the fluorescence detection device of the present invention.

FIG. 6 is a layout diagram of an excitation light oblique irradiation section in the fluorescence detection device of the present invention.

FIG. 7 is a diagram of a test pattern of the fluorescence detection device of the present invention.

FIG. 8 is a diagram showing a test pattern of the fluorescence detection device of the present invention.

FIG. 9 shows resist line width measurement results using the fluorescence detection device of the present invention.

FIG. 10 is an explanatory diagram of the operation of the light guide used in the present invention.

FIG. 11 is a cross-sectional view of a trench structure in a semiconductor wafer.

FIG. 12 is a layout diagram of an oblique irradiation section and a vertical irradiation section of excitation light in the fluorescence detection device of the present invention.

FIG. 13 is an explanatory diagram of the state of total reflection of excitation light within the resist residue in the present invention.

FIG. 14 is a computer control system diagram in the fluorescence detection device of the present invention.

FIG. 15 is an example of a fluorescence intensity spectrum of a resist material.

FIG. 16 is an example of a fluorescence intensity spectrum of a resist material.

FIG. 17 is a waveform diagram of fluorescence in the pulse excitation method.

FIG. 18 is a sectional view of an excitation light irradiation angle adjusting device according to the present invention.

FIG. 19 is a sectional view of a light guide irradiation angle adjusting device according to the present invention.

FIG. 20 is a perspective view of a light guide irradiation angle adjusting device according to the present invention.

FIG. 21 is another computer-based control system diagram in the fluorescence detection device of the present invention.

FIG. 22 is an example of fluorescence intensity spectra of various foreign substances.

FIG. 23 is an example of fluorescence intensity spectra of various positive resist materials.

[Explanation of symbols]

1 Excitation light source 2 Filter 3 Observation light 4 Beam splitter 5 Objective lens 6 Monochromator 7 Detector 8 Driver 9 Computer 10 Scanning stage 11 Sample 12 Resist remaining 13 Resist remaining 21 Excitation filter insertion port 22 Diaphragm 30 Optical fiber 31 Light guide 32 Filter 33 Optical fiber 34 Half mirror 40 Image intensifier 42 Absorption filter 43 Anode phosphor 44 Lens 45 Imaging device 46 Microchannel electron multiplier 47 Photocathode 50 Housing 51 Covering 60 Computer 61 Image memory 62 Display 63 Drive device 70 Angle adjustment device 71 Gear 72 Motor 73 Rack 74 Pinion 76 board 77 Guide groove 78 pin 110 Variable filter 120 Variable filter 421 Microchannel

Claims (18)

[Claims] Claim 1: A fluorescence detection device that irradiates a sample surface with excitation light, detects a fluorescence image emitted by the sample using an image intensifier, and converts the output image into an electrical signal using an imaging device, wherein the excitation light is A semiconductor/mask fluorescence detection device characterized by being equipped with a means for irradiating the sample surface obliquely. 2. The semiconductor/mask fluorescence detection device according to claim 1, wherein the irradiation means irradiates the excitation light obliquely to the sample surface from all directions around the sample. 3. The semiconductor/mask fluorescence detection according to claim 1, further comprising means for irradiating the excitation light perpendicularly to the sample surface in addition to the excitation light oblique irradiation means. Device. 4. In a fluorescence detection device that irradiates the sample surface with excitation light, detects a fluorescence image emitted by the sample using an image intensifier, and converts the output image into an electrical signal using an imaging device, the irradiation of the sample surface A semiconductor/mask fluorescence detection device comprising a plurality of excitation light irradiation means with different angles and irradiation directions. 5. The semiconductor/mask fluorescence detection according to claim 1, further comprising means for irradiating visible light perpendicularly to the sample surface in addition to the means for irradiating the excitation light obliquely. Device. 6. The semiconductor/mask fluorescence detection device according to claim 1, further comprising means for changing the excitation light irradiation angle of the excitation light oblique irradiation means. 7. In any one of claims 1 to 5, the excitation light oblique irradiation means includes an optical fiber device that introduces the excitation light from the light source device into the fluorescence detection device, and an optical fiber device that introduces the excitation light from the light source device into the fluorescence detection device; A semiconductor/mask fluorescence detection device characterized by comprising an optical fiber mounting means that penetrates and holds the inside of a fluorescence detection device housing and can further adjust the mounting angle, mounting position, etc. of the optical fiber device. . 8. The semiconductor/mask fluorescence detection apparatus according to claim 4, further comprising irradiation switching means for selecting one of the plurality of excitation light irradiation means and irradiating the sample surface. 9. The semiconductor/mask fluorescence detection apparatus according to claim 1, further comprising means for changing the wavelength of excitation light from said irradiation means. 10. The semiconductor/mask fluorescence detection device according to claim 1, further comprising means for changing the detection wavelength of the fluorescence. 11. In any one of claims 1 to 10, the excitation light irradiation angle of the excitation light oblique irradiation means is set to an angle at which the excitation light propagates through total reflection within a foreign substance on the sample surface. A semiconductor/mask fluorescence detection device featuring: 12. The method according to claim 1, further comprising means for polarizing the excitation light of the irradiation means and means for detecting fluorescence emitted by the sample via a polarizing plate. Semiconductor/mask fluorescence detection device. 13. The method according to claim 1, further comprising means for intermittent excitation light from the irradiation means and means for detecting fluorescence emitted by the sample after the excitation light is cut off. Semiconductor/mask fluorescence detection device. 14. In claim 6 or 7, the excitation light irradiation angle sweeping means and the maximum value in an image intensifier output that changes in response to a change in the irradiation angle swept by the irradiation angle sweeping means. calculation means for detecting the irradiation angle in relation to the irradiation angle value, and after the irradiation angle sweep operation of the irradiation angle sweep means, the irradiation angle of the irradiation angle sweep means is adjusted to the maximum output of the image intensifier output by the calculation means. A semiconductor/mask fluorescence detection device characterized in that a corresponding irradiation angle value is set. 15. In claim 14, a storage device stores an irradiation angle value corresponding to a maximum output of the image intensifier in association with a name of a material emitting fluorescence on the sample; A semiconductor/mask fluorescence detection device characterized by comprising a calculation means for statistically processing the plurality of irradiation angle values for a material emitting the same fluorescence on a sample and calculating the most probable value thereof. 16. In claim 10, the image indicator changes in accordance with the excitation light wavelength changed by the excitation light wavelength changing means and the fluorescence wavelength changed by the fluorescence detection wavelength changing means. an image intensifier, comprising a calculation means for detecting the maximum value in the intensifier output in relation to the excitation light wavelength and the fluorescence wavelength, and wherein the calculation means outputs the wavelengths of the excitation light and fluorescence after the wavelength changing operation; A semiconductor/mask fluorescence detection device characterized in that the value is set to a value corresponding to the maximum output. 17. The storage device according to claim 16, which stores excitation light wavelengths and fluorescence wavelengths corresponding to the maximum output of the image intensifier in association with names of resist materials on the sample; 1. A semiconductor/mask fluorescence detection device comprising a calculation means for statistically processing a plurality of excitation light wavelengths and fluorescence wavelengths for the same resist material on a sample to calculate the most probable value thereof. 18. A means for irradiating a sample surface with visible light; an image signal of a sample surface pattern obtained by the visible light irradiation; and a sample obtained by the excitation light irradiation. a storage device for storing a fluorescence image signal on a surface; a superimposed superimposed image of a sample surface pattern image by the visible light irradiation stored in the storage device and a fluorescence image by the excitation light irradiation; 1. A semiconductor/mask fluorescence detection device characterized by comprising: imposing means.