JP5450337B2 - Inspection device - Google Patents

Description

  The present invention relates to an inspection apparatus and an inspection method.

  For example, the present invention relates to a surface inspection apparatus and a surface inspection method for examining defect distribution information and flatness information existing on the surface of a semiconductor wafer using a laser beam.

  A semiconductor device is manufactured by polishing, crystal growth, ion implantation, etc., on a thin wafer obtained by slicing a high-purity silicon ingot.

  At this time, minute foreign matters and defects existing on the surface of the wafer strongly affect the yield of semiconductor device fabrication.

  Therefore, an inspection for obtaining distribution information of foreign matters and defects on the surface of the wafer is required in each process of semiconductor device creation. A surface inspection apparatus is used in the above inspection.

  An example of a wafer surface inspection apparatus is disclosed in Patent Document 1.

  In the surface inspection apparatus disclosed in Patent Document 1, a wafer is placed on an inspection stage and moves in a radial direction while being rotated. At that time, the wafer is irradiated with laser light, and scattered light from foreign matters or defects existing on the surface of the wafer is received by a plurality of detectors.

  Then, the obtained data such as foreign matter or defect is processed and output to a file or a display.

  Further, in the production of a semiconductor device having a fine circuit pattern, flatness measurement may be performed in consideration of the thickness and unevenness of the wafer.

  The flatness of the wafer is measured by an electrostatic sensor or an optical interferometer. Patent Document 2 discloses an example of a wafer flatness measuring apparatus.

JP 2007-225480 A JP 2001-33215 A

  In the surface inspection apparatus using scattered light disclosed in Patent Document 1, the position of the defect can be specified, but detailed information in the height direction cannot be obtained.

  In addition, one defect formed in a relatively wide range may be recognized as a plurality of defects.

  In addition, the flatness measuring device disclosed in Patent Document 2 can acquire height information and can correctly acquire a relatively wide range of information, but has a low horizontal resolution.

  Here, it is considered that if the information of the surface inspection device and the information of the flatness measuring device are integrated, a more detailed defect analysis can be performed. Integration is not easy.

  Conventionally, a surface inspection apparatus for inspecting defects existing on the wafer surface and a wafer flatness inspection apparatus exist individually.

  Therefore, when it is desired to inspect the wafer for defects and flatness on the wafer production line, each inspection apparatus is required.

  This has problems such as an increase in capital investment and a decrease in installation location.

  In the prior art, these points have not been considered. The present invention solves the above-described problems, for example.

  An object of the present invention is to provide a wafer inspection apparatus with a defect inspection system and a flatness inspection system so that wafer defect and flatness information can be obtained by a single inspection. It is in.

  The present invention has the following features.

  The present invention includes a fixing unit that fixes a substrate, a transport system that rotates and linearly moves the fixing unit, and a scattering optical system that is disposed on a path of the linear movement and that specifies a position of a defect present on the substrate. And a flatness measuring system arranged on the path of the linear movement and arranged before or after the scattering optical system.

According to the present invention, the fixed part has a hollow structure, the flatness measurement system includes a first interference optical system, a second interference optical system, and the first interference optical system on the fixed part. Placed in
The second interference optical system is arranged inside the hollow structure.

  The present invention is characterized in that the fixed portion has a plurality of openings larger than the size of the spot light irradiated from the first interference optical system or the second interference optical system.

  The present invention is characterized in that the oscillation wavelength of the first interference optical system is longer than the oscillation wavelength of the scattering optical system.

  The present invention is characterized in that the oscillation wavelength of the second interference optical system is longer than the oscillation wavelength of the scattering optical system.

The present invention has the following effects. The following effects may be played independently or in combination.
(1) According to the present invention, the state of a wafer can be analyzed in more detail than before.
(2) According to the present invention, it is possible to realize an analysis of a wafer state that is much more detailed than before, at a low cost.
(3) According to the present invention, it is possible to realize a more detailed analysis of the state of the wafer than in the past in a space-saving manner.

1 is a simplified diagram of a surface inspection apparatus according to Embodiment 1. FIG. Details of interference optics. The figure which shows a mode that the 1st observation window 302 and the 2nd 303 are provided. The figure which shows a mode that the circular observation window 301 is provided. The figure which shows a mode that the observation window 301 is provided in the spiral. Defect information on the surface of the wafer 101. Three-dimensional information of the wafer 101. An example in which two test results are displayed in combination. The inspection sequence in the surface inspection apparatus of the first embodiment.

  Hereinafter, it demonstrates using drawing.

  In the surface inspection apparatus and the surface inspection method of the present invention, a wafer is mainly used as an inspection object, but other than that, it can be applied to a glass substrate of a liquid crystal panel, a solar cell panel, and the like.

  Here, a wafer will be described as an example with reference to the drawings.

  FIG. 1 shows a simplified diagram of the surface inspection apparatus according to the first embodiment.

  The surface inspection apparatus according to the present embodiment is mainly configured by an information processing unit that integrally processes information of one common transport system, two measurement systems described later, and two measurement systems.

  First, the transport system will be described.

  In the transport system, the wafer 101 which is an object to be inspected is fixed to the inspection stage 103 by vacuum suction on the back surface.

  A hollow inspection stage 103 to which the wafer 101 is fixed is installed on a scanning mechanism 102 that moves linearly in a uniaxial direction.

  Further, the inspection stage 103 is rotated at high speed by the spindle 120.

  In the surface inspection apparatus of this embodiment, there are two measurement systems for inspecting the wafer 101.

  First, the first measurement system will be described.

  The first measurement system is a scattering optical system that mainly specifies the position and size of defects.

  In the scattering optical system, the center of the wafer 101 is illuminated by the vertical illumination light 104 from the vertical direction or the oblique illumination light 105 from the oblique direction having a certain elevation angle with respect to the surface of the fixed wafer 101.

  Therefore, in combination with the operation of the transfer system described above, the entire surface of the wafer 101 is inspected from the center of the wafer 101 to the outside.

  Then, scattered light from defects existing on the surface of the wafer 101 is detected by one or a plurality of photodetectors 106 (photomultiplier tubes or the like) installed above the inspection stage 103.

  The detection result is processed by the information processing unit 110, and the position of the defect and the size of the defect are specified.

  In the information processing unit 110, the defect may be classified based on the direction of scattered light from the defect.

  In addition, the inspection result is displayed on the output device 112.

  Next, the second measurement system will be described.

  The second measurement system is a measurement system that performs flatness measurement (in one expression, three-dimensional information considering deflection of the wafer) in consideration of the thickness and unevenness of the wafer 101.

  The second measurement system is on the linear movement path of the transport system and is arranged behind the scattering optical system.

  With this arrangement, defect inspection and flatness measurement can be performed simultaneously in one inspection.

  Note that the second measurement system may be disposed before the scattering optical system.

  In this embodiment, two interference optical systems (upper interference optical system 107 and lower interference optical system 108) will be described as an example of the second measurement system.

  These two interference optical systems are installed so as to sandwich the wafer 101 vertically.

  The flatness measurement is performed from the outside to the inside of the wafer 101 by the rotation operation of the inspection stage 103 and the linear operation of the scanning mechanism 102.

  The upper interference optical system 107 is installed on the linear movement path of the scanning mechanism 102 and above the inspection stage 103.

  The lower interference optical system 108 is installed on the linear movement path of the scanning mechanism 102 and below the inspection stage 103.

  The interference optical systems at the upper part and the lower part of the inspection stage 103 are installed so as to inspect the front and back of the same point of the wafer 101.

  The upper interference optical system 107 is fixedly installed, and the lower interference optical system 108 is installed in the inspection stage 103 having a hollow structure.

  The lower interference optical system 108 moves linearly in the direction relatively opposite to the direction in which the wafer 101 moves horizontally by the drive mechanism 109.

  The moving method of the drive mechanism 109 is ball screw feed, linear rail, wheel or the like. The drive mechanism 109 is fixed with respect to the rotation direction of the wafer 101.

  A linear movement of the scanning mechanism 102, a rotation operation of the inspection stage 103, and a driving mechanism 109 that moves the lower interference optical system 108 are controlled by a control unit 111.

  In addition, the control unit 111 manages the value of the position being inspected, and gives the coordinate value to the information processing unit.

  Next, details of the interference optical system will be described.

  FIG. 2 shows details of the two interference optical systems described above.

  In the two interference optical systems, the laser light oscillated from the light source 201 is divided into the upper interference optical system 107 and the lower interference optical system 108 by the half mirror 202.

  The light to the lower interference optical system 108 is further reflected by the mirror 207.

  Each laser beam branched by the half mirror 202 enters the PBS 203 (polarization beam splitter) and is divided into P-polarized light and S-polarized light.

  P-polarized light is reference light, and S-polarized light is inspection light.

  The P-polarized light that is the reference light passes through the quarter-wave plate and is reflected by the reference mirror 205.

  S-polarized light that is inspection light passes through the quarter-wave plate and is applied to the wafer 101.

  The inspection light is irradiated on the wafer 101, the reflected light and the reference light are caused to interfere with each other, and the interference phase is measured by the photodetector 206.

  The photodetector 206 is a CCD, a camera, or a line sensor.

  With such a configuration, the flatness and thickness of the wafer 101 can be measured from the phase difference between the upper interference optical system 107 and the lower interference optical system 108.

  Here, the number of light sources 201 of the interference optical system is not limited to one.

  Moreover, you may have the light source 201 for every interference optical system.

  The same or close oscillation characteristics of the light source 201 are desirable because measurement errors can be reduced.

  Further, it is desirable that the oscillation wavelengths of the interference optical system and the scattering optical system are different. This is to prevent erroneous detection of the light of the interference optical system as light from a defect.

  More specifically, it is desirable that the oscillation wavelength of the interference optical system is longer than the oscillation wavelength of the scattering optical system.

  The reason is that generally, the oscillation wavelength of the scattering optical system is on the order of several hundreds of nanometers, so that the wavelength shorter than this becomes the absorption wavelength of the wafer 101.

  In addition, by placing a color filter corresponding to the oscillation wavelength of the interference optical system in front of the detector 106 of the scattering optical system, the interference optical system light is erroneously detected as light from a defect. Can be prevented.

  Next, the inspection stage 103 will be described with reference to FIG.

  If the inspection stage 103 has a structure in which a vacuum suction hole is opened on a single plate when the wafer 101 is sucked on the back surface, inspection light from the lower interference optical system 108 disposed under the inspection stage 103 is applied to the wafer 101. I won't win.

  Therefore, in the first embodiment, as shown in FIGS. 3A to 3C, an observation window 301 is provided on the inspection stage 103 so that the inspection stage 103 can be irradiated with inspection light from below from the wafer 101.

  The observation window 301 is an opening that penetrates the inspection stage 103.

  It is desirable that the size of the opening is at least larger than the spot light of the interference optical system so that the inspection light can pass through.

  The observation window 301 is a hole that is perforated at a right angle to the inspection stage 103 or a hole that is perforated at an angle.

  The observation window 301 is arranged as shown in FIGS.

  3 represents the observation window, and the gray portion represents the portion that adsorbs the wafer 101 on the back surface.

  FIG. 3A shows a state in which a linear first observation window 302 and a second 303 are provided radially from the center of the inspection stage 103.

  Here, when the observation window is formed in a linear shape extending radially from the center of the wafer 101, the distance between the observation windows increases as it goes to the outer periphery, and an area where flatness cannot be measured is enlarged.

  Therefore, in FIG. 3A, a second observation window 303 shorter than the first observation window 302 is provided between the two first observation windows 302.

  As a result, it is possible to prevent an increase in the area where the flatness cannot be measured due to an increase in the interval between the observation windows on the outer periphery.

  FIG. 3B shows a state in which circular observation windows 301 are provided radially from the center of the inspection stage 103.

  Here, when the wafer 101 is inspected by rotating it at a constant speed, the time during which the laser light passes through the same inspection area is different between the outer peripheral portion and the inner peripheral portion.

  The laser beam passage time is shorter on the outer periphery.

  For this reason, the observation window 301 is formed densely on the inner peripheral side of the wafer 101 and sparsely on the outer peripheral side as shown in FIG. It is better to keep it.

  FIG. 3C shows a state in which the observation window 301 is provided in a spiral shape from the center of the inspection stage 103.

  Of course, the shape of the observation window 301 may be other than that shown in FIGS.

  Although not shown in FIG. 3, a plurality of air suction ports for fixing the wafer 101 are provided in a portion where the wafer 101 is attracted to the back surface.

  The flatness information of the wafer 101 in the portion other than the observation window 301 is estimated from the peripheral flatness information. This processing is performed in the information processing unit 110.

  Next, the details of the inspection result displayed on the output device 112 will be described.

  FIG. 4A shows defect information on the surface of the wafer 101 obtained by the scattering optical system.

  A round dot represents a position of a defect existing on the surface of the wafer 101.

  FIG. 4B shows three-dimensional information (such as thickness information in consideration of deflection) of the wafer 101 obtained by the interference optical system.

  The darker the color, the thicker the reference thickness of the registered wafer 101 is.

  Next, details of a display example in which the above two inspection results are combined will be described.

  FIG. 5 shows an example in which the inspection results of FIG. 4 (a) and FIG. 4 (b) are combined and displayed.

  As a result, the relative relationship between the thickness and deflection of the wafer 101 and the defect distribution can be known without any deviation in the coordinate system.

  Next, details of the inspection sequence in the surface inspection apparatus according to the first embodiment will be described with reference to FIG.

  First, in the first embodiment, the operator can select whether to perform both the defect inspection and flatness inspection on the surface of the wafer 101 or only one of them.

  The operator selects whether to perform both defect inspection and flatness inspection on the surface of the wafer 101 or only one of them (601).

  When performing defect inspection and flatness inspection simultaneously, the scattering optical system and the interference optical system are prepared so as to be inspected (602).

  After completing the preparation of each optical system, laser oscillation is performed, and at the same time, the inspection stage 103 is rotated and defect inspection and flatness inspection are started (603).

  After each inspection (604), the defect information and flatness information, which are inspection results, are displayed on the output device 112, and the inspection ends (605).

  When the simultaneous inspection is not selected, that is, when only one of the defect inspection and the flatness inspection is inspected, only one of the interference optical system and the scattering optical system is prepared (612).

  Then, the selected inspection is performed (613).

  After the inspection is completed (614), the inspection result is displayed (615).

  In the above embodiment, the back surface adsorption method is used as a method of holding the wafer 101 on the inspection stage 103, but other methods may be used.

  For example, there is a method in which several points or all the circumferences of the edge portion of the wafer 101 are sandwiched and held on the inspection stage 103.

  Even in this case, as in the above-described embodiment, when the inspection is performed while the wafer 101 is linearly moved while rotating, the interference optical system installed below the wafer 101 is moved in the direction opposite to the moving direction of the wafer 101. The same effect as Example 1 can be produced.

101 Wafer 102 Scanning Mechanism 103 Inspection Stage 104 Vertical Illumination Light 105 Oblique Illumination Light 106, 206 Photodetector 107 Upper Interference Optical System 108 Lower Interference Optical System 109 Drive Mechanism 110 Information Processing Unit 111 Control Unit 112 Output Device 201 Light Source 202 Half Mirror 203 PBS
204 1/4 wavelength plate 205 Reference mirror 207 Mirror 301 Observation window

Claims (5)

In an inspection device for inspecting a substrate,
A fixing part for fixing the substrate;
A transport system for rotating and linearly moving the fixed portion;
A scattering optical system that is arranged on the linear movement path and identifies the position of a defect present on the substrate;
An inspection apparatus comprising: a flatness measurement system disposed on the linear movement path and disposed in front of or behind the scattering optical system. The inspection apparatus according to claim 1,
The fixing part has a hollow structure,
The flatness measurement system has a first interference optical system and a second interference optical system,
The first interference optical system is disposed on the fixed portion,
The inspection apparatus, wherein the second interference optical system is disposed inside the hollow structure. The inspection apparatus according to claim 2,
2. The inspection apparatus according to claim 1, wherein the fixing unit has a plurality of openings larger than a spot light irradiated from the first interference optical system or the second interference optical system. The inspection apparatus according to claim 2,
The inspection apparatus according to claim 1, wherein an oscillation wavelength of the first interference optical system is longer than an oscillation wavelength of the scattering optical system. The inspection apparatus according to claim 2,
2. The inspection apparatus according to claim 1, wherein an oscillation wavelength of the second interference optical system is longer than an oscillation wavelength of the scattering optical system.

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