JP2005098773A - Surface inspection apparatus for inspecting presence or absence of cracks in semiconductor substrate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a surface inspection apparatus for substrates, capable of detecting processors which processor have troubles in composite semiconductor manufacturing equipment, consisting of a plurality of substrate processors made in-line. <P>SOLUTION: The schlieren-method surface inspection apparatus 1 is provided with a temporary placement table 2 for mounting a semiconductor substrate; a detection part 19 for detecting the presence or absence of discontinuous parts, when grayscale distribution data on images acquired be a photographing part 15 is differentiated; an image-classifying part 18 for determining whether the detected discontinuous parts are cracks or stains on the basis of their size; and a data processing part 16 for outputting photographed images on a display 20. In the photographing part 15, a light irradiated from a light source 3 is diffused in parallel by a collimator 4 and refracted by a beam splitter 7, to direct parallel beams towar the side of the back surface of the semiconductor substrate; the parallel beams are condensed onto the surface of the semiconductor substrate via a schlieren microscope 11 provided with both a varifocal lens and a silicon lens; and light reflected at the surface of the semiconductor substrate is passed through the beam splitter 7 to form an image in a camera 12. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention is based on an image obtained by placing a semiconductor substrate having a printed wiring on the front surface and a flat back surface on a temporary mounting table with the back surface facing upward, and picked up by a Schlieren imaging method. The present invention relates to a surface inspection apparatus for inspecting whether or not a crack exists in the semiconductor substrate.

  In the semiconductor manufacturing apparatus, a plurality of processes are performed in the pre-process and post-process of the substrate. For example, a process of grinding a back surface of a semiconductor substrate having a printed wiring on the front surface and a flat back surface, a step of polishing the back ground surface of the semiconductor substrate to make a mirror surface, and a frame of the back ground semiconductor substrate And the like, a step of mounting using an adhesive tape, a step of peeling off the dicing tape, a dicing step, and the like. Conventionally, each of these processes has been batch-processed, but a semiconductor substrate manufacturing manufacturer requires a multi-chamber type semiconductor manufacturing apparatus in which a plurality of chambers for performing these processes are connected in-line, and has been put into practical use. . For example, a step of grinding the back surface of the semiconductor substrate, a step of polishing the back-ground surface of the semiconductor substrate to make a mirror surface, and a step of mounting the back-ground semiconductor substrate on the frame using an adhesive tape This is an apparatus for a pretreatment process in which a chamber to be performed is in-line (for example, see Patent Document 1).

  In a multi-chamber type semiconductor manufacturing apparatus, each chamber is used to reliably detect damage (cracks) and cracks generated in a part of a semiconductor substrate and to minimize damage to the semiconductor manufacturing apparatus due to the scratches and cracks. It is preferable to take an image of the entire semiconductor substrate before moving the processed semiconductor substrate to the chamber for the next processing and humbly identify the image to determine whether it is normal or abnormal.

  In conventional batch-type manufacturing equipment, the operator verified the presence or absence of scratches that could not be visually determined on the processed semiconductor substrate by enlarging the substrate surface with an optical microscope. Recently, a predetermined pattern is projected onto an inspection surface of a semiconductor substrate, an image of the inspection surface on which the pattern is projected is acquired, and at least a gray-scale distribution pattern of the acquired image is acquired. -It has been proposed to detect cracks in a semiconductor substrate using a mask (see, for example, Patent Document 2).

  In addition, an optical system capable of imaging the same location at different focal positions, an image input unit that captures an image obtained from the optical system, and a standard applied to the input image by moving the input image by a predetermined amount The reference image is generated, and the image data output from the image input unit is processed by pipeline processing using a data flow type processor without being stored in the memory, and dust, foreign matter, and shape defects are detected. An inspection apparatus including an image processing unit that performs detection has also been proposed (see, for example, Patent Document 3).

Further, the light irradiated from the laser beam is diffused in parallel by the first collimator lens, and the light that has passed through the semiconductor substrate is condensed by the second collimator lens and formed into an image, which is then converted into a CCD camera. A schlieren imaging method has also been proposed. In this Schlieren imaging method, half of the light emitted from the laser beam and the light collected by the second collimator lens are shielded by the knife edge. (See Patent Document 4). The schlieren imaging method is suitable for crack inspection of a substrate having a mirror surface such as a silicon substrate.
JP 2002-151450 A JP 2003-185590 A JP 2000-180377 A US Pat. No. 6,181,416

  The problem to be solved by the present invention is not to take out the processed semiconductor substrate one by one out of the chamber and place it on an inspection table installed outside the chamber to inspect for cracks in the substrate, An object of the present invention is to provide a surface inspection apparatus capable of performing a surface inspection within a line of an in-line semiconductor manufacturing apparatus. In order to use the schlieren photographing method described in the above-mentioned US Patent, a temporary placement table in a chamber used in a semiconductor manufacturing apparatus or a temporary placement table provided between lines has a stage portion on which a substrate is placed as an opaque member. Therefore, it is necessary to replace the stage portion with one made of a transparent member and to provide a camera on the lower surface of the stage portion. In the present invention, a schlieren imager can be installed above a stage.

  According to the first aspect of the present invention, there is provided a temporary mounting table on which a semiconductor substrate having a printed back surface and a flat back surface is placed with the back surface facing upward, and light irradiated from an infrared irradiation light source is diffused in parallel by a collimator lens. Refracting by a beam splitter and directing parallel rays toward the back side of the semiconductor substrate, condensing the parallel rays on a semiconductor substrate surface through a Schlieren microscope having a variable focus lens and a silicon lens, An imaging unit that passes the beam splitter through the beam splitter and forms an image on the camera, and the light that passes through half of the collimator lens and half of the camera lens is blocked by a knife edge. , A detection unit for detecting the presence or absence of a discontinuous portion when differentiating the grayscale distribution data of the image acquired by the photographing unit, and the detected discontinuous portion is cracked or dirty from its size Image classification unit to determine, de outputs the captured image on the display - and provides a lens process surface inspection apparatus - Sri and a data processing unit.

  In the surface inspection apparatus using the schlieren method of the present invention, an imaging unit including a light source and a camera can be installed on the upper side of the temporary table, so that there is no need to significantly change the structure of an existing semiconductor device.

(Example 1)
FIG. 1 is a side view of a surface inspection apparatus of the present invention, FIG. 2 is an image of a substrate projected on a display screen by a schlieren imaging method, and FIG. 3 is an example of a semiconductor manufacturing apparatus in which a plurality of chambers are inlined. FIG. 4 is a plan view showing an example of a semiconductor manufacturing apparatus in which a plurality of chambers showing another embodiment are inlined.

  In the surface inspection apparatus 1 using the schlieren imaging method shown in FIG. 1, w is a semiconductor substrate, the front surface side a is printed, covered with a protective tape c, and the back surface b is flat. It is. Reference numeral 2 denotes a temporary mounting table on which the substrate is placed with the back surface facing upward, 3 denotes an infrared irradiation light source, 4 denotes a first collimator lens, and 5 denotes a knife edge, which constitute a light source irradiation mechanism 6. Reference numeral 7 denotes a beam splitter, 8 denotes a compound lens, 9 denotes a variable condenser lens, and 10 denotes a silicon lens, which constitute a Schlieren microscope 11. A camera 12 is connected to the Schlieren microscope 11. A knife edge 13 is placed in front of the camera lens. Reference numeral 14 denotes an outer cylinder of a Schlieren microscope. The light source irradiation mechanism 6, the Schlieren microscope 11, the knife edge 13, and the camera 12 constitute an imaging unit 15. Reference numeral 16 denotes a data processing unit, 17 denotes an image storage unit, 18 denotes an image classification unit, 19 denotes an input / output unit, 20 denotes a display (CRT), 21 denotes a mouse, and 22 denotes a keyboard.

  The outer cylinder 14 of the surface inspection apparatus 1 is fixed to a support member 23, and is configured such that a slider 25 moves in the left-right direction (x direction) on a rail 24 provided vertically on the front surface of the support member 23. . In other words, the Schlieren microscope 11 of the surface inspection apparatus 1 can also be moved in the left-right direction by moving the slider 25 in the left-right direction. The support member 23 is fixed to the front surface of a vertical sliding plate 26 whose back surface is screwed to a ball screw (not shown) that rotates upon receiving the rotational drive of a servo motor 27. That is, when the servo motor 27 is driven to rotate, the vertical sliding plate 26 moves on a guide rail (not shown) provided on the front surface of the fixed plate 28, thereby causing a Shrelen microscope. 11 is also movable in the vertical direction (y direction).

  The fixed plate 28 is fixed to the front surface of the column 29, and the column 29 is fixed to the lower part of the sliding body 30 that slides on the guide rails 31 and 31 stretched in the horizontal direction. The sliding body 30 can be moved in the front-rear direction (z direction) by driving a servo motor, a ball screw and a screwed body (not shown). In other words, the Schlieren microscope 11 of the surface inspection apparatus 1 can also be moved in the front-rear direction by the movement of the sliding body 30 in the front-rear direction.

  For imaging the back surface of the substrate w, the semiconductor substrate w is placed on the temporary table 2 with the back surface facing upward, half of the light emitted from the infrared irradiation light source 3 is shielded by the knife edge 5, and the first collimator lens 4. Diffracted in parallel, refracted by the beam splitter 7, directed parallel light rays to the back side of the semiconductor substrate w, and condensed through the Schlieren microscope 11 on the semiconductor substrate surface. The light reflected from the substrate surface passes through the beam splitter 7, and half of the light passing therethrough is shielded by the knife edge 13 and then imaged on the camera 12.

  The image storage unit 17 receives the image signal transmitted from the camera 12 of the photographing unit 15, and the detection unit 19 differentiates the density distribution data of the image signal to detect the presence or absence of the discontinuous portion. The image classification unit 18 determines whether the output signal of the discontinuous portion detected by the detection unit 19 is a crack or a dirt from the size (including the length). The image picked up by the image pickup unit 15 is displayed on the display 20 by an output signal transmitted from the data processing unit 16 (see FIG. 3). If necessary, a signal for displaying the presence or absence of cracks and dirt on the display 20 may be transmitted from the output unit 19 and displayed on the display 20 together with the image of the substrate.

  In the image of the substrate surface displayed on the display shown in FIG. 2, the flat surface of the semiconductor substrate is displayed in a light gray color, and the crack 500 and polishing dust 600 are displayed in a dark black color. The distinction between cracks and polishing debris is that the debris is microscopic, the size is several microns to several tens of microns, is a discontinuous dot, the crack is macroscopic, and length Is in the unit of mm and is a continuous straight line or curved line, so that it is distinguished by the data processing unit.

  This substrate surface inspection apparatus 1 is an appearance of a semiconductor substrate processed in each chamber in a multi-chamber type semiconductor manufacturing apparatus in which a plurality of chambers provided with a plurality of substrate processing apparatuses are connected in-line. Is used for inspecting the appearance of the semiconductor substrate in each chamber or on a temporary table for delivery to the next process.

  An in-line substrate processing apparatus 100 shown in FIG. 3 includes a grinding apparatus 101 for grinding a back surface of a semiconductor substrate disclosed in Patent Document 1 (Japanese Patent Laid-Open No. 2002-151450), and a back-ground surface of the semiconductor substrate. Before each chamber of the mounter apparatus 200 for performing the process of mounting the semiconductor substrate subjected to the etching process to a mirror surface and mounting the semiconductor substrate subjected to the back grinding / etching process on the frame using the adhesive tape is inlined. The apparatus of a process process is shown.

In the substrate processing apparatus 100 in which the back surface grinding apparatus, the etching apparatus, and the mounter apparatus shown in FIG. 3 are inlined, reference numeral 101 denotes a back surface grinding apparatus, 120 denotes an etching apparatus, 200 denotes a mounter apparatus, and 300 denotes an inline wafer transfer apparatus.
The back grinding apparatus 101 is arranged in a front row with a pair of cassettes 117 on the left and right, a substrate temporary table 106 at the rear of the left cassette on the base, and a cleaning mechanism 113 at the rear of the right cassette. And an index turntable 108 is provided at a position where the central portion of the temporary table 106 and the base of the rear part of the cleaning mechanism 113 is cut out, and the index turntable is provided with the shaft of the table. Three substrate chuck mechanisms 107 are rotatably provided at equal intervals around the center, and the table is divided into substrate loading / substrate unloading zone, rough grinding zone and finish grinding zone. In the rear row of the index turn table 108, a grinding mechanism in which a grinding wheel suitable for each grinding zone is supported on the spindle shafts 111a and 111c on a frame body 111 standing upright from a base is provided for each grinding zone. It is provided corresponding to the substrate chuck mechanism located down.

  An articulated transfer robot 115 is erected substantially at the center between the pair of cassettes 117 and the temporary placement table 106 and the cleaning mechanism 113, and the device wafer on the temporary placement table 106 is indexed. It can be transferred to the chuck mechanism of the table substrate loading / substrate unloading zone.

  The suction pads 112 provided on the handle rotatably attached to a pair of shafts provided on the left and right of the substantially central portion of the base on which the index turn table is provided respectively support the device wafer of the temporary placement base. -The back-ground device wafer on the chucking mechanism 117 of the loading / substrate unloading zone and on the chuck mechanism of the substrate loading / substrate unloading zone is transferred onto the spinner of the cleaning mechanism 113. .

  The etching apparatus 120 is surrounded by a side wall 121, and the etcher 126 is further surrounded by an inner partition wall 122. Reference numeral 125 denotes a transfer robot, and 133 denotes a shutter mechanism.

  In the grinding apparatus 101, the substrate w transported onto the temporary table 106 by the articulated robot 115 from the loading cassette 117 is attracted to the transport pad 112, and the transport pad is rotated to rotate the index table 118. The loading / unloading zone chuck mechanism 107 is mounted, the index table is rotated 120 degrees clockwise, and the chuck mechanism 107 moves to the first grinding zone.

  Therefore, the wafer w is roughly ground with a rough grinding wheel supported by the first spindle shaft 111a, and then the roughly ground wafer is sent to the finish grinding zone by rotating the index table 118 by 120 degrees. . Therefore, the substrate that has been finish-ground by the finish grinding wheel supported by the second spindle shaft 111c and then finished by turning the index table 118 by 120 degrees is loaded into the loading / unloading zone. Be transported.

  The finish-ground substrate is adsorbed by the transfer pad 112 on the right side, transferred to the cleaning mechanism 113, cleaned and spin-dried by the cleaning mechanism, and then passed through the opening of the partition wall by the transfer robot 125 in the etching apparatus 120. Then, the substrate is transferred to the etcher 126, where the substrate is etched, washed, spin-dried, and transferred to the temporary table 301 by the articulated robot 125.

  While the substrate is finish-ground by the finish grinding wheel supported by the second spindle shaft, a new substrate is transferred from the loading cassette 117 to the temporary table 106 by the articulated robot 115, Therefore, the substrate is adsorbed by the transport pad 112, the index table 118 is rotated 120 degrees and placed on the rough grinding chuck mechanism 107, and the substrate is roughly ground by a rough grinding wheel supported by the first spindle shaft. . In this way, since rough grinding and finish grinding of the wafer are performed simultaneously, the throughput time of the wafer grinding apparatus can be shortened.

  An inline wafer transfer apparatus 300 is provided on the front wall of the etching apparatus 120. The inline wafer transfer apparatus 300 includes a temporary placement table 301, a temporary placement table rotation mechanism, a temporary placement table reciprocating mechanism in the horizontal direction, and a transparent dome. The temporary placement table 301 moves the temporary placement table 301 to the position indicated by the phantom line by rotating the support arm 302 of the temporary placement table by 90 degrees by the rotation mechanism. The temporary table 301 indicated by the phantom lines is moved to the front wall 201a side (right direction) of the mounter device 200 by driving the belt 315, and the sensor 313 is a rotary table support table constituting the temporary table. When the presence is caught (the temporary table is at the position indicated by the phantom line in FIG. 1), a signal is transmitted to the control device, and a drive stop command is issued from the control device to the motor with a reduction gear. Is stopped, and the movement of the belt is also stopped.

The mounter apparatus 200 is surrounded by side walls 201a, 201b, 201c, and 201d, and the front wall 201a has an opening 202 through which the temporary placement table 301 of the inlined wafer transfer apparatus 300 can enter and exit. The upper surface is covered with a ceiling 203 to form a chamber 204 with side walls and a ceiling.
An arm 205 is supported on a base 206 by a support shaft 207 in the section chamber 204, and a wafer suction plate 210 is fixed to a side surface of the arm 205 with a long bowl 211. The rod 211 can be moved up and down by a cylinder 212, the cylinder 212 is installed so as to be movable in the horizontal direction on the rail 213, the rail 213 is received by the slider -214, and the slider -214 reciprocates the groove 215 back and forth. I can move. The reciprocating drive mechanism of the slider-214 is omitted from the drawing.

  The hollow portion of the suction plate 210 is connected to a vacuum pump (not shown), and the substrate suction plate 210 can suck the device surface covered with the protection tape of the device wafer w by reducing the pressure of the hollow portion. .

  A recognition camera for confirming the alignment of the substrate is provided above the substrate suction plate 210 and contributes to the centering adjustment of the device wafer w that has been placed on the temporary table 301 and transferred. That is, the recognition camera checks whether the center point of the temporary placement table 301 and the center point of the device wafer w coincide with each other in the vertical direction. The center points coincide with each other by moving the cylinder 212 on the rail 213 in the left-right direction so that the center point of the device wafer w coincides with the center point of the temporary placement table 301 and the slider-214 receiving the rail 213 in the groove 215. Move back and forth to decide. The center point of the temporary placement table 301 and the frame center point of the chamber portion 219 are determined by the sensor installation position of the in-line wafer transfer apparatus 300 described later so as to be on the same line m.

  Reference numeral 216 denotes a frame holder, which is constructed by stacking frames F each having an adhesive tape T adhered to the lower surface thereof, so that the bottom plate can be raised by the height of one frame by a cylinder from below. Yes. Reference numeral 217 denotes a suction jig 218a attached to a shaft 218 that can reciprocate in the left-right direction, with a frame M1 having an adhesive tape attached to the lower surface of the uppermost stage sent out from the frame holder 216. After the centering on the belt 218b is completed by moving it to the left, the vacuum of the suction jig is stopped to open the frame M, and then the belt 218b is rotationally driven intermittently to move to the left. 219 is an alignment and transfer mechanism for transferring to 219.

  Next, the device wafer w adsorbed on the substrate adsorbing plate 210 is advanced backward, the cylinder is lowered, and is adhered to the adhesive tape surface affixed to the frame on the chamber mechanism 219. The device wafer is mounted on the adhesive tape affixed to the frame by stopping the pressure reduction of the wafer suction plate 210, raising the wafer suction plate 210, and retracting it in the forward direction.

  A frame transport / rotation mechanism 220 is provided at the rear of the chamber mechanism 219. The frame transport / rotation mechanism 220 reverses the frame from the chamber mechanism 219 by rotating the rotation shaft 224 by 180 degrees with the motor 223 of the arm 222 engaged with the jig 221. Then, one end of the frame is brought into contact with the side end of the transport arm 225, and the frame M is moved in the backward direction indicated by the arrow by a transport mechanism (not shown) to move to the storage transport path 226, where the frame is moved. The frame M is moved and stored in the cassette 227 rotated 90 degrees.

  The surface inspection apparatus 1 according to the present invention is provided on the temporary mounting table 301 of the etching apparatus 120 of the substrate processing apparatus 100 inlined.

  FIG. 4 shows an in-line substrate processing apparatus 100 showing another embodiment, in which instead of the back surface grinding apparatus 101 and the etching apparatus, a polishing apparatus 120 ′, a UV irradiation / DAF bonding machine (mounter apparatus) 200, and a dicing tape application. Machine / grind tape remover 400 inline. The surface inspection apparatus 1 of the present invention is provided on the temporary placement table 301 of the UV irradiation / DAF pasting machine (mounter apparatus) 200 of the inlined substrate processing apparatus 100 and on the mounted substrate transport mechanism 226. . In FIG. 4, the surface inspection apparatus 1 is provided at a position within a circle indicated by a crack detection and a virtual arrow.

  In a semiconductor manufacturing apparatus in which a plurality of substrate processing apparatuses are inlined, it is possible to determine in which processing chamber the substrate processing is insufficient when cracks or dust adhere to the substrate is detected.

It is a side view of a surface inspection apparatus. (Example 1) It is the image of the board | substrate projected on the display screen by the schlieren imaging method. It is a top view of the semiconductor manufacturing apparatus with which the some chamber was made in-line. (Known) It is a top view which shows an example of the semiconductor manufacturing apparatus with which the some chamber which shows another aspect was made in-line.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Surface inspection apparatus w Semiconductor substrate 2 Temporary table 3 Light source 4 1st collimator lens 5 Knife edge 6 Light source irradiation mechanism 7 Beam splitter 8 Compound lens 9 Variable condensing lens 10 Silicon lens 11 Shrelen microscope 12 Camera (detection) vessel)
13 Knife edge 15 Imaging unit 16 Data processing unit

Claims (1)

  Temporary mounting table on which a semiconductor substrate with a printed back surface and a flat back surface is placed with the back surface facing up, light irradiated from an infrared irradiation light source is diffused in parallel by a collimator lens, and refracted by a beam splitter A parallel light beam is directed to the back side of the semiconductor substrate, and the parallel light beam is condensed on the surface of the semiconductor substrate through a Schlieren microscope equipped with a variable focus lens and a silicon lens, and the light reflected on the semiconductor substrate surface is reflected on the bi-directional surface. An imaging unit that passes through a half-splitter and forms an image on the camera, and the light passing through half of the collimator lens and half of the lens of the camera is acquired by the imaging unit having a structure that is blocked by a knife edge; A detection unit for detecting the presence or absence of a discontinuous portion when differentiating the gray-scale distribution data of the detected image, and an image portion for determining whether the detected discontinuous portion is a crack or a dirt from its size Ren method surface inspection apparatus - Sri and a data processing unit - part, de outputting the captured image to the display unit.

Images