JP6232129B2 - Wafer prober system capable of wafer surface inspection - Google Patents

Description

  The present invention relates to a wafer prober system, and more particularly, requires a separate time for wafer surface inspection by performing wafer surface inspection before and after the probing process for a plurality of dies formed on the wafer. None can perform the probing process, and by accurately grasping the state before and after the probing process, the wafer prober can perform more accurate wafer probing and can also grasp the probing state About the system.

  In a semiconductor manufacturing process, after forming a large number of chips having semiconductor elements on a wafer, the electrical characteristics of each chip are inspected, and each chip is separated using a cutting device. It is used in the form.

  Wafer prober system is a semiconductor manufacturing system that fixes a wafer to a stage, makes contact with the electrode pads of each chip on the wafer and a probe equipped with a tester, and inspects the electrical characteristics of each chip on the wafer to determine the defect of each chip. It is one of the inspection equipment in the process. In this wafer prober system, the pads of each die formed on this wafer are directly contacted and tested, and defective dies are removed at an early stage so that the subsequent packaging process and packaging test process can be performed. Process equipment to reduce raw materials used, time, and other losses.

  The conventional wafer prober system described above uses a stage unit (Stage Unit) for moving and fixing a wafer to be inspected on a chuck, a tester for inspecting the electrical characteristics of the wafer using a prober card, and a wafer handling robot arm. And a loader unit (Loader Unit) for moving the wafer, a pre-alignment unit (Pre-Alignment Unit) for adjusting the center and direction of the wafer, and a control unit (Control Unit) for controlling the overall operation. Yes.

  The stage part is an instrument part composed of a chuck and four axes, and the four axes are on the X and Y axes moving on a plane and the X and Y axes, respectively. The chuck includes a Z-axis that is installed and moves up and down, and a rotary shaft that rotates on the Z-axis. The chuck is installed on the rotary shaft. Therefore, the chucks installed on the above four axes can move with four degrees of freedom of plane, top and bottom, and rotation, and the wafer to be tested is fixed on the above chucks. Become so.

  The loader unit unloads the wafer to be tested from the cassette using the robot arm and supplies it to the sub-chuck of the pre-alignment unit, or the pre-aligned wafer is chucked on the provo. Or a test-completed wafer from the stage chuck is carried in the cassette.

  The prober card is a card that transmits and receives electrical signals by providing an electrical connection with the wafer in order to inspect the wafer, and the tester inspects electrical signals transmitted and received from the prober card. Then, by creating and mounting a program for inspecting whether or not various wafers are manufactured as desired, inspection suitable for each wafer can be performed. The above prober card is fixed to the upper plate of the stage unit by taking charge of electrical connection between the wafer and the tester mounted on the chuck of the above stage unit. A single pin is placed to point the chuck. At this time, all pins of the prober card are designed to coincide with the pads on the die of the wafer in order to make an accurate electrical connection between the tester and the wafer on the chuck.

  The pre-alignment unit performs the alignment in advance with respect to the center and direction of the wafer by raising the wafer to be tested on the slab chuck before the wafer in the cassette is transferred onto the chuck of the provo.

  In the wafer prober system having the above-described configuration, after the wafer to be tested is fixed on the chuck of the stage unit, the pad portion which is the point to be tested on the wafer is brought into contact with the prober probe pin. Let Next, the tester transmits an electrical signal for testing the state of the chip inside the wafer placed on the chuck by the prober card, and the electrical signal transmitted by the prober card is transmitted to the prober card. It is transmitted to the pad inside the wafer through the provo pin. At this time, the pre-alignment unit transports the wafer in the cassette onto the sob chuck before transporting the wafer on the stage chuck, and after searching for the center of the wafer, moves the wafer to the center of the sobchock. And the center of rotation of Sovtic. After pre-aligning the wafer on the sob chuck, the wafer is transferred onto the stage chuck.

  On the other hand, conventionally, a wafer surface inspection device (Inspection Device) is provided separately from the wafer prober system, and the surface condition of the wafer in each cassette is inspected by using the wafer surface inspection device described above. Information can be provided to the wafer prober system described above. Thus, conventionally, since the wafer prober system and the wafer surface inspection equipment were separated, a separate space for installing the wafer surface inspection equipment had to be prepared, and for the wafer surface inspection. Needed extra time. In addition, conventionally, since the surface inspection was completed after the probing was completed for all the wafers in the cassette, the problem could not be immediately confirmed when a problem occurred during the probing. There is a problem that defects are generated in all the wafers of the lot.

  Also, when probing multiple times using several prober cards for a single wafer, the probing marks generated on the wafer by the probing process using each prober card can be separated and confirmed. There wasn't. As a result, even if a probing problem occurred, it was almost impossible to confirm which prober card caused the probing process.

  An object of the present invention to solve the above-described problems is to provide a wafer prober system further equipped with a wafer surface inspection device, and while waiting for the next wafer probing while probing the first wafer. Another object of the present invention is to provide a wafer prober system that does not require additional time for wafer surface inspection by performing wafer surface inspection.

  Another object of the present invention is to perform wafer surface inspection before / after the wafer probing process, and compare and analyze the results of the wafer surface inspection to determine whether or not the wafer probing is accurate. It is to provide a wafer prober system.

  The feature of the wafer prober system according to the present invention for achieving the technical problem described above is that a wafer is handled by using a stage unit for placing a wafer to be tested on a chuck and moving the chuck to a desired position, and a wafer handling robot. Before probing a wafer in a wafer prober system comprising a loader for transporting the wafer, a tester for probing the wafer by inspecting the electrical characteristics of the wafer on the chuck using a prober card, and a controller. A wafer surface inspection unit for performing wafer surface inspection at or after,

  The wafer surface inspection unit includes a wafer mounting table on which a wafer is mounted, an imaging unit that images the surface of the wafer mounted on the wafer mounting table, and the imaging unit for imaging An illumination unit that provides illumination to the wafer mounting table, and a scanning unit that can move the imaging means.

  The control unit uses a loader to move the wafer whose surface is to be inspected to the wafer mounting table, and drives the imaging means and the scanning unit of the wafer surface inspection unit to be mounted on the wafer mounting table. The wafer surface is imaged to acquire an image of the wafer surface, the acquired image of the wafer surface is analyzed to generate wafer surface inspection information, and the generated wafer surface inspection information is used in the wafer probing process. It is desirable to do.

  In the wafer prober system according to the above-described features, the control unit moves the second wafer to be probed to the wafer surface inspection unit while the first wafer is probing on the stage unit, and performs wafer surface inspection. Proceed to generate wafer surface inspection information, and when the probing of the first wafer is completed, place the second wafer on the chuck of the stage unit and perform wafer surface inspection on the second wafer. Probing with information is desirable,

  In the wafer prober system according to the above-described features, the wafer surface inspection information includes at least one of information on the bump state and position of each chip, PMI (Probing Mark Inspection) information on each chip, and pad state information on each chip. It is desirable to include more than one.

  In the wafer prober system according to the above-described feature, the control unit moves the second wafer to be probed next to the wafer surface inspection unit while the first wafer is probing on the stage unit, and the first surface Proceeding the inspection to generate first surface inspection information for the second wafer,

  When the probing for the first wafer is completed, the second wafer is placed on the chuck of the stage unit, and probing is performed using the first surface inspection information for the second wafer,

  When the probing for the second wafer is completed, the second wafer is moved to the wafer surface inspection unit, and the second surface inspection proceeds to generate second surface inspection information for the second wafer. age,

  The first and second surface inspection information includes information on the bump state and position of each chip before and after probing, pad state information on each chip before and after probing, and before and after probing, respectively. It is desirable to include one or more of the PMI information for each chip.

  The wafer prober system according to the present invention performs the wafer surface inspection during the standby time for wafer probing, so that no additional time is required for the wafer surface inspection.

  The wafer prober system according to the present invention can use the wafer surface inspection unit to inspect the position of bumps formed on each die of the wafer and the possibility of defects before wafer probing.

  The wafer prober system according to the present invention can acquire information on the PMI of each die by acquiring an image of the wafer surface before / after the wafer probing process using the wafer surface inspection unit.

  Conventionally, since the wafer surface inspection equipment and the wafer prober system were separated, the wafer surface inspection was performed after the completion of probing for all the wafers in one cassette, so that the wafer prober was used during the probing process. Even if a problem occurs in the system, it is difficult to confirm immediately. After probing has been completed for all the wafers in the cassette, it is possible to confirm whether or not the problem has occurred. Defects are generated in all the wafers.

  On the other hand, the wafer prober system according to the present invention can perform wafer surface inspection in real time when probing for one wafer is completed, and can confirm the occurrence of a problem in real time. Therefore, the production efficiency can be improved.

  In addition, the wafer prober system according to the present invention can perform wafer surface inspection both before and after probing, and by comparing and analyzing the results of wafer surface inspection before and after probing, the probing can be accurately performed. It can be determined whether or not it has been performed. Further, the state of each chip of the wafer after probing can be inspected, and the probing mark generated by probing can be directly confirmed.

  In fact, it is difficult to determine whether each probing has been performed accurately in the conventional wafer prober system, although a single wafer can be probed many times with different prober cards. It is. However, the wafer prober system according to the present invention performs the wafer surface inspection both before and after each probing, and compares and analyzes the state of the probing mark before and after the probing, thereby probing the results of each prober card. Can be managed. Therefore, according to the present invention, it is possible to manage by which prober card each probing mark formed on the wafer is generated, and the position and depth of each probing mark.

  The wafer prober system according to the present invention can generate alignment information for each die of a wafer using a wafer surface inspection unit when probing a wafer with a frame diced to each die. As a result, the alignment information can be generated during the standby time, so that the time required for the probing process for the framed wafer can be reduced.

FIG. 1 is a block diagram schematically illustrating a wafer prober system according to a preferred embodiment of the present invention. FIG. 2 is a schematic perspective view schematically illustrating a wafer prober system according to an exemplary embodiment of the present invention. FIG. 3 is a perspective view schematically illustrating one actual example of the wafer surface inspection unit 140 in the wafer prober system 1 according to the preferred embodiment of the present invention. FIG. 4 is a flowchart illustrating a process of probing a single wafer according to a first example of the operation of the controller in the wafer prober system according to the preferred embodiment of the present invention. FIG. 5 is a flowchart illustrating a process of sequentially probing a plurality of wafers by the controller according to the first practical example of the operation of the controller in the wafer prober system according to the preferred embodiment of the present invention. FIG. 6 is a flowchart illustrating a process of probing a single wafer according to a second example of the operation of the controller in the wafer prober system according to the preferred embodiment of the present invention. FIG. 7 is a flowchart illustrating a process of sequentially probing a plurality of wafers by the control unit according to the second example of the operation of the control unit in the wafer prober system according to the preferred embodiment of the present invention. FIG. 8 is a perspective view schematically showing another example of the wafer surface inspection unit 240 in the wafer prober system 1 according to the preferred embodiment of the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION

  The wafer prober system according to the present invention can eliminate the time required for the wafer surface inspection by performing the wafer surface inspection during the probing standby time before and after the wafer probing, and before and after the probing process. By checking the state of the die, more accurate probing can be performed. Also, the wafer prober system according to the present invention can perform accurate alignment during the waiting time before probing when probing a wafer with a frame that is diced into each chip. The time required for the probing process can be reduced.

  Hereinafter, the structure and operation of a wafer prober system according to an exemplary embodiment of the present invention will be described in detail with reference to the accompanying drawings.

  1 and 2 are a block diagram and a schematic perspective view schematically illustrating a wafer prober system according to an exemplary embodiment of the present invention. 1 and 2, a wafer prober system 1 according to the present invention uses a stage unit 100 for placing a wafer to be tested on a chuck and moving the chuck to a desired position, and a wafer handling robot. A loader 110 for transporting the wafer, a tester 120 for probing the wafer by inspecting the electrical characteristics of the wafer on the chuck using a prober card, a control unit 130 for controlling the entire operation, and a wafer A wafer surface inspection unit 140 that performs wafer surface inspection before or after probing, and a pre-alignment unit 150 that pre-aligns the wafer by adjusting the center and orientation of the wafer to be probed. In the above-described wafer prober system, the stage unit, the loader, and the tester are the same as the conventional functions, and thus the description thereof is omitted.

  FIG. 3 is a perspective view schematically illustrating one actual example of the wafer surface inspection unit 140 in the wafer prober system 1 according to the preferred embodiment of the present invention.

  Referring to FIG. 3, the wafer surface inspection unit 140 includes a wafer mounting table 142 on which a wafer is mounted, an imaging unit 144 that images the surface of the wafer mounted on the wafer mounting table, An illumination unit 146 that provides illumination to the wafer mounting table for imaging by the imaging unit, and a scanning unit 148 that can move the imaging unit in the vertical and horizontal directions.

  The control unit 130 moves a wafer whose surface is to be inspected to a wafer mounting table using a loader, and drives the imaging unit and the scanning unit of the wafer surface inspection unit to place the wafer on the wafer mounting table. The wafer surface is imaged by acquiring an image of the wafer surface, the wafer surface image is analyzed to generate wafer surface inspection information, and the wafer is generated using the generated wafer surface inspection information. Probing

  Hereinafter, various practical examples of the operation of the wafer prober system according to the preferred embodiment of the present invention will be described in detail.

  FIG. 4 is a flowchart illustrating a process of probing a single wafer according to a first example of the operation of the controller in the wafer prober system according to the preferred embodiment of the present invention. Referring to FIG. 4, the control unit first takes out the wafer from the cassette using the wafer handling robot of the loader and moves it to the pre-alignment unit (step 400). After adjusting the direction and pre-aligning, it is moved to the wafer surface inspection unit (step 410), the wafer surface inspection unit acquires the image of the wafer surface and generates the wafer surface inspection information, and then moved to the stage unit ( In step 420, the wafer is probed on the stage (step 430) and loaded again in the cassette (step 440).

  FIG. 5 is a flowchart illustrating a process of sequentially probing a plurality of wafers by the controller according to the first practical example of the operation of the controller in the wafer prober system according to the preferred embodiment of the present invention. Referring to FIG. 5, the first wafer is unloaded from the cassette, pre-aligned by the pre-alignment unit (step 510), moved to the wafer surface inspection unit, wafer surface inspection (step 512), and moved to the stage unit. The wafer is probed (step 514) and loaded into a cassette.

  While the first wafer is probed (step 514), the second wafer is unloaded from the cassette, pre-aligned by the pre-alignment unit (step 520), moved to the wafer surface inspection unit, and wafer surface inspection is performed ( Step 522) Wait until the first wafer has been probed. Next, when the probing of the first wafer is completed and loaded into the cassette, the second wafer is moved to the stage unit, wafer probing (step 524), and loaded into the cassette.

  While the second wafer is being probed (step 524), the third wafer is unloaded from the cassette, pre-aligned by the pre-alignment unit (step 530), moved to the wafer surface inspection unit, and wafer surface inspection is performed ( Step 532), waiting for the second wafer to complete probing. Next, when the probing of the second wafer is completed and loaded into the cassette, the third wafer is moved to the stage unit, wafer probing (step 534), and loaded into the cassette.

  By repeatedly performing the above-described process on a large number of wafers stored in one cassette, wafer surface inspection and wafer probing are sequentially performed on all the wafers in the cassette. At this time, the wafer prober system according to the present invention allows the wafer surface inspection to proceed while waiting for the next probing wafer while one wafer is being probed. Has the advantage of not requiring time.

  The wafer surface inspection information obtained by the wafer surface inspection in the wafer surface inspection unit includes information on the state and position of bumps for each chip on the wafer, probing mark inspection (hereinafter referred to as “PMI” for each chip on the wafer). "Includes" one or more of the information. Here, the PMI information includes information such as a position and a depth for each probing mark and a series of information for a probing process in which each probing mark is formed.

  The control unit performs wafer probing using information on bumps or alignment information on each die in the wafer surface inspection information, and determines whether probing has been performed accurately using information on probing marks.

  FIG. 6 is a flowchart illustrating a process of probing a single wafer according to a second example of the operation of the controller in the wafer prober system according to the preferred embodiment of the present invention. Referring to FIG. 6, the control unit first takes out the wafer from the cassette using the wafer handling robot of the loader, moves it to the pre-alignment unit (step 600), and the center and direction of the wafer in the pre-alignment unit. Is adjusted and pre-aligned, and then moved to the wafer surface inspection unit (step 610). After the wafer surface inspection unit acquires the image of the wafer surface and generates the first surface inspection information, it is moved to the stage unit. (Step 620) After probing the wafer at the stage unit, the wafer surface inspection unit is moved again (Step 630), and the wafer surface inspection unit also acquires the image of the wafer surface to generate second surface inspection information. (Step 640), the cassette is loaded again (Step 650).

  According to the above-described embodiment, the control unit obtains first and second surface inspection information before and after wafer probing, respectively. Therefore, the first and second surface inspection information acquired by the wafer surface inspection in the wafer surface inspection unit includes information on the state and position of the bump for each chip of the wafer, and the wafer before and after the wafer probing. PMI information for each chip, that is, one or more of information on the position and state of the probing mark (Probing Mark).

  The control unit can perform wafer probing using information on bumps in wafer surface inspection information, and can determine whether or not probing has been performed accurately using PMI information after probing is completed. Then, by comparing and analyzing the first and second surface inspection information before and after the wafer probing, it can be determined whether or not the wafer probing has been performed accurately. In particular, by comparing the probing marks before and after the wafer probing, it can be determined whether or not the probing process has been performed at the correct position and with the correct intensity.

  FIG. 7 is a flowchart illustrating a process of sequentially probing a plurality of wafers by the control unit according to the second example of the operation of the control unit in the wafer prober system according to the preferred embodiment of the present invention. Referring to FIG. 7, the first wafer is unloaded from the cassette, pre-aligned by the pre-alignment unit (step 710), moved to the wafer surface inspection unit, and the primary wafer surface inspection is performed to obtain the first surface inspection information. Is generated (step 712), moved to the stage unit, wafer probed (step 714), moved to the wafer surface inspection unit, and subjected to secondary wafer surface inspection to generate second surface inspection information (step 716). , Is loaded into the cassette.

  While the first wafer is probing (step 714), the second wafer is unloaded from the cassette, pre-aligned by the pre-alignment unit (step 720), moved to the wafer surface inspection unit, and the primary wafer surface inspection is performed. (Step 722) and wait until the first wafer has been probed. Next, when the probing of the first wafer is completed and the wafer is moved to the wafer surface inspection portion for the secondary wafer surface inspection (step 712), the second wafer is moved to the stage portion and is subjected to wafer probing (step). 724), and is moved to the wafer surface inspection section, where the secondary wafer surface is inspected and second surface inspection information is generated (step 726), which is carried into the cassette.

  While the second wafer is probing (step 724), the third wafer is unloaded from the cassette, pre-aligned by the pre-alignment unit (step 730), moved to the wafer surface inspection unit, and the primary wafer surface inspection is performed. (Step 732) and wait until the second wafer is probing complete. Next, when the probing of the second wafer is completed and the wafer is moved to the wafer surface inspection portion for the secondary wafer surface inspection (step 722), the third wafer is moved to the stage portion and is subjected to wafer probing (step). 734), the wafer surface inspection unit is moved to the secondary wafer surface inspection to generate second surface inspection information (step 736), which is carried into the cassette.

  By repeatedly performing the above-described process on a large number of wafers stored in one cassette, wafer surface inspection and wafer probing are sequentially performed on all the wafers in the cassette. At this time, the wafer prober system according to the present invention allows the wafer surface inspection to proceed while waiting for the next probing wafer while one wafer is being probed. Has the advantage of not requiring time.

  On the other hand, in the wafer prober system according to a preferred embodiment of the present invention, when probing a framed wafer that is diced into dies, the wafer surface inspection unit is used to generate alignment information for each die of the framed wafer. Then, accurate probing can be performed on the framed wafer using the alignment information. In particular, the time required for the probing process for the framed wafer can be reduced geometrically by performing alignment on the framed wafer at the wafer surface inspection unit during the probing standby time. In the conventional wafer prober system, when probing a framed wafer, the alignment must be performed with a chuck for probing, so there was a problem that additional time required for alignment was required. The wafer prober system according to the present invention can completely eliminate the time required for alignment.

  Therefore, when probing a framed wafer using the wafer prober system according to the present invention, the alignment time for each die of the framed wafer can be eliminated, thus greatly reducing the overall time required for the probing process. be able to.

  FIG. 8 is a perspective view illustrating another embodiment of a wafer surface inspection unit in a wafer prober system according to a preferred embodiment of the present invention. Referring to FIG. 8, the wafer surface inspection unit 240 according to the present experimental example is characterized in that the image pickup unit includes two cameras 244 and 245. The first camera 244 is composed of a low-magnification camera that captures a low-magnification video, which can be used when imaging a low-magnification video that can acquire information on bumps. In this case, it is desirable to use a low-magnification camera capable of a bump size of a minimum of 30 microns and a maximum of 300 microns.

  The second camera 245 is composed of a high-rate camera that captures a high-rate video, which can be used to acquire PMI information or to capture other high-resolution video.

  Although the present invention has been described above mainly with reference to desirable practical examples, this is merely an example and is not intended to limit the present invention. It will be understood that various modifications and applications not exemplified above are possible without departing from the essential characteristics of the present invention. Such differences in modification and application should be construed as being included in the scope of the present invention as defined in the appended claims.

  The wafer prober system according to the present invention can be widely used in semiconductor manufacturing processes.

Claims (8)

A stage unit for placing the wafer to be tested on the chuck and moving the chuck to a desired position, a loader for transferring the wafer using a wafer handling robot, and a wafer on the chuck using a prober card. In a wafer prober system comprising a tester for inspecting electrical characteristics and probing a wafer, and a control unit,
A wafer surface inspection unit for performing wafer surface inspection before or after probing the wafer;
The wafer surface inspection unit is
A wafer mounting table on which the wafer is mounted;
Imaging means for imaging the surface of the wafer mounted on the wafer mounting table;
An illumination unit that provides illumination to the wafer mounting table for imaging by the imaging unit;
A scanning unit capable of moving the imaging means,
The controller uses a loader to move the wafer whose surface is to be inspected to the wafer mounting table, and drives the imaging means and scanning unit of the wafer surface inspecting unit to place the surface of the wafer placed on the wafer mounting table. To acquire a wafer surface image, analyze the acquired wafer surface image to generate wafer surface inspection information, and use the generated wafer surface inspection information for probing the wafer. A wafer prober system capable of performing wafer surface inspection ,
The wafer surface inspection information includes information on the bump state and position of each chip on the wafer, and PMI information on each chip on the wafer,
The control unit drives the wafer surface inspection unit to acquire PMI information for the wafer before and after probing the wafer.
Wafer prober system that can perform wafer surface inspection . The controller is
While the first wafer is probing on the stage part, the second wafer to be probed next is moved to the wafer surface inspection part, and the wafer surface inspection proceeds to generate wafer surface inspection information,
2. The method according to claim 1, wherein when the probing of the first wafer is completed, the second wafer is placed on a chuck of a stage unit, and probing is performed using wafer surface inspection information for the second wafer. 1. A wafer prober system capable of performing the wafer surface inspection described in 1.   3. The wafer capable of performing wafer surface inspection according to claim 1, wherein the wafer surface inspection information includes arrangement information for each die in a wafer with a frame in a state of being diced to each die. Prober system.   The wafer prober system capable of performing wafer surface inspection according to claim 1, wherein the imaging means includes a low magnification camera and a high distribution camera. The controller is
The low-power camera is driven to acquire a low-magnification image when inspecting a bump state, and the high-rate camera is driven to capture a high-rate image when trying to acquire PMI information. 4. A wafer prober system capable of performing the wafer surface inspection described in 4 . The controller is
While the first wafer is probing at the stage portion, the second wafer to be probed next is moved to the wafer surface inspection portion, and the first surface inspection proceeds to provide first surface inspection information for the second wafer. Produces
When the probing for the first wafer is completed, the second wafer is placed on the chuck of the stage unit, and probing is performed using the first surface inspection information for the second wafer,
When the probing for the second wafer is completed, the second wafer is moved to the wafer surface inspection unit, and the second surface inspection proceeds to generate second surface inspection information for the second wafer. A wafer prober system capable of performing wafer surface inspection according to claim 1. The first surface inspection information includes PMI information for each chip before probing,
7. The wafer prober system according to claim 6 , wherein the second surface inspection information includes PMI information for each chip after probing. 7. The wafer prober system according to claim 6 , wherein the control unit analyzes the first and second surface inspection information to determine the probing state.

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