Semi-automatic prober

Semi-automatic detector

Semi-automatic prober

The present invention is related to semiconductor wafer testing. In particular, the present invention relates to a semi-automatic system for testing electrical devices on silicon wafers.

Semiconductor reliability tests such as well-known wafer level reliability (WLR) tests are typically performed by wafer detectors at ambient temperatures as high as 350°C. Regarding electrical testing of semiconductor wafers, while the semiconductor wafer (mounted on a chuck) moves into electrical contact with the probe card, a set of probes on the probe card are typically supported in place. The wafer can be vacuum mounted on the heating chuck. After the die (or array of die) has been electrically tested, the detector then moves the wafer to the next die (or array) to start the next test. The wafer prober usually also loads or unloads wafers from its carrier (or cassette). The wafer detector can also have automatic pattern recognition optics that can align the contact pads on the wafer and the tip of the probe.

The positional accuracy and repeatability of wafer chuck movement are extremely important for satisfactory wafer contact. The size of the contact pads in the wafer is getting smaller and smaller, making the position accuracy very important. Therefore, I hope that the position can be determined Wafer probe station with accuracy, diversity and convenience.

According to the embodiment, a wafer probe station is provided. The wafer probe station includes an interface that can accept modules selected from a plurality of different interchangeable modules. Each module is configured to join at least one probe card and the wafer, and the modules can be exchanged with different modules.

According to another embodiment, a front-loaded wafer probe station is provided, which has a chamber. The probe station includes a pivoting arm and two wafer support sections. Each wafer support section is rotatably installed on the pivoting arm, and the wafer support section can move between a position indoors and a position at least partially outdoors.

According to another embodiment, a method for loading a wafer into a wafer probe station is provided. Set up the wafer probe station. The wafer probe station has a wafer loading mechanism with a frame covered in the room. The wafer loading mechanism includes a pivoting arm and two wafer support sections. Each wafer support section is rotatably installed on the pivoting arm, and the wafer support section can move between a position indoors and a position at least partially outdoors. The chuck is moved from the test position to the loading position. The test location and loading location are indoors. Rotate the pivot arm to move the wafer support section at least partially outdoors. The wafer is then loaded into the wafer support section. Rotate the pivot arm to move the wafer support section and the wafer back into the room, and load the wafer from the wafer support section into the chuck.

<p>10Probe card</p><p>12Printed Circuit Board</p><p>14Slit</p><p>16Probe tip</p><p>18Support</p><p>20Electrical connectors and fasteners</p><p>22Metal Tracking</p><p>24Electrical contact</p><p>25Probe head</p><p>26Bolt Fastener</p><p>30Support rail</p><p>32Probe head</p><p>34Control knob</p><p>36Control knob</p><p>38Control knob</p><p>40Shrink cable</p><p>42Internal passage</p><p>44Internal Channel</p><p>48Component</p><p>50Dovetail flange</p><p>54Open</p><p>56Leverage mechanism</p><p>1000Probe station</p><p>1010Mounting plate</p><p>1015Chuck</p><p>1016Support rail</p><p>1017Non-leakage mask</p><p>1018Microscope assembly</p><p>1020Probe Positioner</p><p>1022Platform</p><p>1024Pedest</p><p>1028Adapter arm</p><p>1030Track assembly</p><p>1050door</p><p>1060Probe station room</p><p>1100Pivot arm</p><p>1150Wafer support section</p><p>1200wafer</p>

By referring to the following description and accompanying drawings, you can better understand the present invention and its other External purposes and advantages, including:

Fig. 1A is a perspective view of an embodiment of a semi-automatic wafer probe station.

FIG. 1B is a perspective view of an embodiment of a semi-automatic wafer probe station with microscope assembly.

FIG. 1C is a perspective view of an embodiment of a semi-automatic wafer probe station with microscope assembly and light-proof cover.

2A is a perspective view of an embodiment of a semi-automatic wafer probe station with a probe positioner module docked to its mounting plate.

2B is an enlarged perspective view of the embodiment of the semi-automatic wafer probe station shown in FIG. 2A.

2C is a top view of the embodiment of the semi-automatic wafer probe station shown in FIGS. 2A and 2B.

2D is a side view of the embodiment of the semi-automatic wafer probe station shown in FIGS. 2A-2C with a microscope assembly.

Fig. 2E is a side view of the probe positioner according to the embodiment.

Fig. 2F is a front view of the probe head according to the embodiment.

Fig. 2G is a top view of the probe positioner shown in Fig. 2E.

Fig. 2H is a top view of the 8X probe positioner according to the embodiment.

Figure 2I is a top view of an 8X probe positioner according to another embodiment with a longer arm.

Fig. 3A is a perspective view of an embodiment of a probe card.

3B is a perspective view of the embodiment of the probe card shown in FIG. 3A further illustrating the metal tracking of the electrical contacts on the other end of the electrical interconnection probe tip to the printed circuit board.

Fig. 3C is a side view of the probe card shown in Figs. 3A and 3B.

4A is a perspective view of an embodiment of a semi-automatic wafer probe station with an air-cooled rail system module docked to its mounting plate.

4B is an enlarged perspective view of the embodiment of the semi-automatic wafer probe station shown in FIG. 4A.

4C is a top view of the embodiment of the semi-automatic wafer probe station shown in FIGS. 4A and 4B.

4D is a side view of the embodiment of the semi-automatic wafer probe station shown in FIGS. 4A-4C with a microscope assembly.

Fig. 5A is a perspective view of a supporting rail supporting an upright probe card.

Fig. 5B is a cross-sectional view of the support rail shown in Fig. 5A.

Fig. 5C is another perspective view of the track supporting three probe heads.

6A-6D are movement diagrams of the wafer loading mechanism in the embodiment of the wafer probe station.

Fig. 6E is a perspective view of an embodiment of a wafer loading mechanism.

FIG. 7 is a flowchart of a method 700 for accurately landing on a wafer at a temperature above about 300° C. in a wafer probe station.

FIG. 8 is an example diagram of NIST (National Institute of Standards and Technology) traceable reference glass used according to the embodiment.

9 is a flowchart of a method for calculating the offset of a given point in the wafer area based on the measured values 1, 2 and 3 according to an embodiment.

The present invention is related to a system for reliability testing of semiconductor wafers System. The embodiment describes a semi-automatic probe station or probe used for testing semiconductor wafers.

The embodiment of the semi-automatic probe station described here can test dozens to hundreds of devices under test (DUT) at the same time. The probe station can include an anti-vibration table, a leak-proof cover, a digital camera with high-power optics, a vacuum thermal chuck, and a multi-pin mini probe card. With the probe station described here, multiple probe cards can be positioned on the surface of the wafer.

As described in more detail here, the embodiments of the wafer probe station can be used with different modules for wafer testing. For example, modules such as probe card positioners and air-cooled rail systems can be interchanged.

As shown in FIG. 1A, according to an embodiment, the probe station 1000 may be provided with a mounting plate 1010, on which an interchangeable module can be docked or installed to provide users with multiple ways to bond with the test wafer. The test wafer can be loaded into the probe station chamber and positioned on a chuck 1015 that can be heated for testing. FIG. 1B illustrates a probe station 1000 with a microscope assembly 1018 that can be used with the probe station 1000. The microscope assembly 1018 is installed on the support rail 1016. In an embodiment, the supporting rail 1016 also functions as a frame of the light-proof cover 1017, which may include a plurality of retractable panels to form the light-proof cover 1017 with the frame 1016.

The interchangeable module can be installed on the mounting plate 1010 of the individual probe positioner 1020 of the probe station (e.g., single-pin probe positioner, upright probe card positioner, or other types of probe positioners), such as As shown in Figure 1. Other types of modules that can be installed on the mounting plate 1010 include but are not limited to the rail system 1030, the traditional 4.5" card, 6.5" card, and various sizes Round cards, and customized interfaces for high frequency, high pressure, and purified gas, or other customized methods.

According to the embodiment shown in FIGS. 2A-2D, the probe positioner module 1020 is mounted to the platform 1022, which is docked or mounted to the mounting plate 1010 of the probe station 1000. The platform 1022 and the mounting plate 1010 of the probe station 1000 have a common size and mounting hole pattern, allowing users to quickly exchange modules as needed. The interchangeable module can be provided with a handle for easy lifting and positioning of the module. Unused modules can be removed from the probe station 1000 and stored as needed. In the illustrated embodiment, the probe positioner 1020 module is bolted to the appropriate positions of the use bolts and the calibration pins in the common mounting holes of the mounting plate 1010 and the platform 1022. According to other embodiments, cam action latches are provided to enable easy module exchange. The three points of adjustment may be included on the probe station 1000, so that each module can be flattened and calibrated when the module is installed on the mounting board 1010.

In one embodiment, as shown in FIGS. 2A-2D, the module mounted on the probe station 1000 includes two single XYZTs (3-axis linear transfer, and rotation around the Z-axis when considering standard Cartesian coordinates) The probe positioner 1020 is installed on the mounting plate 1010 of the probe station 1000. The positioner 1020 may have a base 1024 based on a magnetic or vacuum support for mounting to the probe station 1000.

The XYZT positioner 1020 is designed to accurately position the probe card (including the standard probe card and the upright probe card) on the probe table 1000 to contact the wafer. As mentioned above, any suitable fasteners (including bolts, clamps, latches, etc.) can be used to install the XYZT positioner 1020 and the platform 1022 on the mounting plate 1010 on. FIG. 2E illustrates an embodiment of the XYZT positioner 1020. In the illustrated embodiment, the XYZT positioner has a pedestal 1024 for mounting to the probe station 1000. The probe card 10 is typically mounted on the probe head 25, as shown in Figure 2F.

According to an embodiment, the XYZT positioner 1020 can be mounted on the mounting plate 1010 of the probe station 1000 in any orientation and in various configurations as shown. In the illustrated embodiment, as shown in FIGS. 2E-2I, the XYZT probe positioner 1020 has an adapter arm 1028 installed with the upright probe card 10. As shown in Figures 2H and 2I, the adapter arm 1028 may have different lengths in different embodiments. The upright probe card 10 can be mounted on the end of the adapter arm 1028 in various orientations to be able to match the wafer pad orientation as needed. With the designated layout and the number of probe heads for a given combination of test equipment, the shrink cable carries the probe heads 25 upwards according to the arrangement, and terminates on the customized interface board. The shrink cable carries the probe card 10 to the external test equipment.

The number and positions of the probe heads 25 are mostly determined by the spacing and orientation of the wafer dies to be tested. Examples of the positioner 1020 are shown in FIGS. 2H and 2I. Each of the embodiments shown in FIGS. 2H and 2I has eight probe heads 25. The embodiment of the positioner 1020 shown in FIG. 2I has an adapter arm 1028 that is longer than the embodiment shown in FIG. 2H. It should be understood that the positioner may have more or fewer probe heads depending on other factors including the size of the positioner and the size of the probe head.

In one embodiment, the XYZT positioner 1020 has a modular adapter arm with a probe head 25 installed at one end for calibration and temporary storage of the upright probe card 10, such as QualiTau from Mountain View, California The upright probe card, etc. available from the company, can be used for device testing on the probe station 1000. Next, an embodiment of the upright probe card 10 will be described with reference to FIGS. 3A-3C. The main problem arises from the heating of the typical horizontal probe card and probe head system. The horizontal probe card is the component closest to the thermal chuck supporting the wafer, and due to temperature dependent leakage current will experience rapid performance degradation. Most of the exposed area of the horizontal probe card makes the performance degradation of the probe more serious. Since device testing will be performed at temperatures up to 300°C, the upright probe card is suitable for testing semiconductor devices at elevated temperatures because the upright probe card maintains electrical signals above and away from the hot chuck.

FIG. 3A is a perspective view of an embodiment of the probe card 10, and includes a printed circuit board 12 having a plurality of slits 14 to help the flow of cold air penetrate therethrough. At one end of the printed circuit board 12 is a tip assembly including a plurality of metal probe tips 16 in a ceramic support 18, and at the opposite end of the printed circuit board 12 are electrical connectors and fasteners 20, which are used physically The support probe is stuck in the test system and connects the probe tip 16 to a flexible (contracted) cable.

3B further illustrates the printed circuit board 12 and the metal trace 22, which electrically interconnect the probe tip 16 to the electrical contacts 24 on the opposite end of the board 12. The metal traced conductive pattern or separation line 22 interconnects the tip of the individual probe to one of the contacts 24. As shown, the ceramic support 18 with the probe tip 16 supported therein is attached to the board 12 via the bolt fastener 26.

3C is a side view of the probe card that engages the socket in the supporting device to support the electrical connector of the probe card 10 and the fastener 20 in a substantially upright or vertical position relative to the wafer under test. Only the end of the tip 16 engages The device under test thereby restricts the flow of heat conduction through the probe tip. The upright alignment of the probe card 10 limits the exposure of the card to the heat dissipated by the chuck of the heating device. Moreover, the convection of air from the heating chuck to the probe card and supporting equipment is blocked by the flow of cold air provided by the supporting assembly, as will be explained below. The probe card 10 is typically mounted on the probe head 25, as shown in Figure 2F.

For various types of devices or test methods used, reliability testing of semiconductor devices requires very different and unique equipment. As discussed above, by allowing users to use the probe station 1000 to interface with probe tips, cards, various patterns and configurations, or other contact methods, the probe station 1000 solves various types of devices and/or test methods. Special needs. According to the embodiment described herein, the probe station 1000 provides a system for connecting with different interchangeable modules.

According to the type of wafer to be tested, the configuration of the probe station 1000 allows the user to easily remove and replace the module. The custom PCB and connector assembly are also designed to be interchangeable, depending on the type of equipment being implemented for electrical testing. These assemblies are designed with inputs for triaxial cables, split lines, coaxial, and other unique cables and connector standards.

In order to increase the flexibility of the reliability analysis step and the repeated testing of the silicon wafer, the removable probe positioner 1020 shown in FIG. 2 can be replaced by a different module assembly. For example, FIGS. 4A-4D illustrate an embodiment of a removable array of air-cooled rails 1030 mounted on the mounting plate 1010 of the probe station 1000, such as those available from Qualitau.

As shown in FIGS. 4A-4D, the air-cooled rail assembly 1030 can be installed on the mounting plate 1010 of the semi-automatic probe station 1000 as an interchangeable module. track The assembly 1030 can test multiple die, which is important to increase the test output over time, and can ensure an appropriate sample size for a given set of test conditions.

The air-cooled rail assembly 1030 and the mounting plate 1010 of the probe station 1000 have a common size and mounting hole pattern, allowing users to quickly exchange modules as needed. The rail assembly 1030 can be provided with a handle for easy lifting and positioning. In the illustrated embodiment, cap bolts and alignment pins are used in the common mounting holes of the mounting plate 1010 and the rail assembly 1030 to latch the rail assembly 1030 module in place. According to other embodiments, a cam action latch is provided to enable easy module exchange.

The rail assembly 1030 includes an array of a plurality of air-cooled support rails 30 for supporting the upright probe card 10. 5A is a perspective view of the support rail 30 supporting the upright probe card 10 and the probe head generally indicated by 32 on the device under test (wafer) and the heating support chuck. In one embodiment, the probe head 32 can be manually adjusted via the three axes along which the control knobs 34, 36, 38 move. According to another embodiment, the user interface can adjust the probe head 32 semi-automatically. The shrink cable 40 is supported on the top of the track 30 and interconnects the probe card 10 to external test equipment. It should be noted that shrinking the cable 40 by overheating will reduce performance.

5B is a cross-sectional view of the rail 30, which includes internal channels 42, 44 for cooling the air flow used by the probe head 32; the probe card 10; and the shrink cable 40. The air from the internal passage is launched through the opening in the track 30, where the air is guided through the probe head 32 and the probe card 10 to interrupt the convective hot air flow from the hot chuck supporting the device under test. therefore, The overheating of the printed circuit board of the shrinkage cable 40 and the test probe 10 can be avoided. In this embodiment, it should be noted that the track 30 includes a member 48 having a dovetail flange that engages the mating dovetail flange of the probe head 32, as shown generally at 50.

FIG. 5C is another perspective view of the rail 30 supporting three probe heads 32. In this embodiment, only one probe card 10 is shown on the probe head to illustrate openings or slots. These openings or slots are used to help cool air from the opening 54 in the frame 30 to flow through the probe. The needle 32 passes through the opening 14 in the probe card 10. It should be noted in this embodiment that each probe head 32 has a lever mechanism generally shown at 56 which can be used to lock the probe head in the dovetail flange 50 of the track 30.

Some probe station systems use cassettes to load wafers from the side. Most conventional probe station systems that load wafers from the front side require the entire chuck assembly to be removed from the probe station. The removal of the chuck assembly has some disadvantages, including: (i) reducing the mechanical stability of the chuck mechanism; (ii) increasing the complexity of the tabletop system, and (iii) if the chuck is immersed in a specific elevated temperature, it will Causes significant temperature changes.

By using a two-piece pivot arm 1100, the embodiment of the probe station 1000 provides a simple and accurate method for this problem. The two-piece pivot arm 1100 can be rotated from the front of the probe station 1000 to accept wafers. At 1200, the wafer 1200 is transported to the surface of the chuck, and then the two wafer support sections 1150 are "opened" to shrink away while still being enclosed in the probe station 1000. This front loading feature for a single wafer 1200 allows users to easily load the wafer 1200 from the front without causing the temperature of the chuck 1015 Changes because the chuck 1015 is maintained in the probe station chamber 1060.

As shown in the illustrated embodiment, the probe station 1000 may be provided with a lower front wafer loading door 1050 to cover and expose an opening on the front surface of the probe station 1000 for loading and unloading wafers. In other embodiments, the doors may have different configurations, such as sliding doors or side swing doors. To help facilitate single wafer loading, the probe station 1000 has an internal frame-covered arm that can rotate outward to retrieve and deliver the wafer 1200 to the thermal chuck 1015.

The front loading mechanism for wafers will be described with reference to FIGS. 6A-6E. FIG. 6E illustrates the inner chamber 1060 of the probe station 1000 as seen from the opening in the front face of the probe station 1000. As shown in FIG. The lowering door 1050 is opened to provide access to a front loading mechanism for wafers 1200 such as 200 or 300 mm wafers. In FIG. 6E, a diagram is shown from the bottom side to illustrate the loading mechanism supporting the wafer 1200, which includes a pivot arm 1100 and two wafer support sections 1150. In the embodiment shown in FIG. 6E, the two wafer supporting sections 1150 rotate around one end of the pivot arm 1100. The other end of the pivot arm 1100 rotates around the pivot point of the platform attached to the probe station 1000.

6A-6D are diagrams of wafer loading processing according to embodiments. As shown in FIG. 6A, the chuck 1015 and the loading mechanism (the pivot arm 1100 and the two wafer support sections 1150) are located in the position covered by the frame, which is also the test position. The frame covering or testing position is the position where the chuck 1015 and the loading mechanism are stored when not in use, and the wafer 1200 is supported by the chuck 1015 and tested. As shown in FIG. 6A, the two wafer supporting sections 1150 are rotated away from each other and away from the chuck 1015.

When the wafer 1200 will be loaded, the user prompts the probe station 1000 series System. When prompted by the software, the chuck 1015 will move from the test position along the X, Y and Z axes to the loading position. As shown in FIG. 6B, the chuck 1015 moves toward the wafer support section 1150 and the door 1050 into the loading position. According to an embodiment, when the chuck 1015 moves toward the wafer support section 1150 and the door 1050, it also moves downward.

The door 1050 is then opened and the two wafer support sections 1150 rotate toward each other, and the pivot arm 1100 rotates the two wafer support sections 1150 forward away from the door opening, so that the wafer 1200 can be loaded on the wafer support section 1150. As shown in FIG. 6C, the wafer 1200 can be placed on the wafer support section 1150 at this position. It should be understood that for simplicity, the chuck 1015 is not shown in FIG. 6C, and the chuck 1015 is actually in the loading position in the moving chamber 1060 as shown in FIG. 6B.

As shown in FIG. 6D, the pivot arm 1100 rotates the two wafer support sections 1150 and the supported wafer 1200 returns to the chamber 1060, and the wafer 1200 can be placed on the chuck 1015 in the loading position in the chamber. In the probe station chamber 1060, the wafer support section 1150 then independently rotates away (returns to the frame covering position). While supporting the wafer 1200, the chuck 1015 is then rotated back to the test position. In the test position, an interchangeable module (eg, probe positioner, track system, etc.) can be used to test the wafer 1200, as described above.

With the traditional probe card construction on the semi-automatic detector, the user is usually limited to a single location, or fixed some locations with limited adjustments. The embodiment of the semi-automatic probe station 1000 can process up to 16 individually adjusted probe heads at a temperature as high as about 300° C., and can easily adjust a single location in the probe head array. This allows users to customize the landing and test The pattern, spacing, and number of test heads. This can also reposition a single head (or more) if the devices in the array fail. The combination of adjustable track and head array and automatic XYZT stage provides a way to maximize flexibility.

In order to accurately arrange the steps and repeat the landing of the wafer probe system, the user must have accurate information about the spacing between the landing pad and the repeated die for testing. There are problems when this information is not known, or these values change due to the thermal expansion of the silicon wafer itself. For example, when the temperature rises to 300°C, the size of a 300mm silicon wafer will expand significantly, and the grain spacing will become more than 25μm larger than at room temperature. In order to correct for this difference, the embodiment of the probe station 1000 uses image processing and pattern recognition routines to detect and measure the spacing of the die for each set of temperatures to compensate for this expansion and ensure accurate landing at any temperature.

FIG. 7 is a flowchart of a method 700 for achieving accurate landing on a wafer at a temperature up to about 300° C. in a wafer probe station. According to this method 700, a database is generated, stored, and referenced by software to accurately compensate for the temperature deviating from the room temperature value. Using image processing and pattern recognition from CCD (Charge Coupled Device), the gasket size and other features can also be automatically measured. In step 710, a database is generated by detecting and measuring the interval of the die at each predetermined temperature, and storing the measured interval for each predetermined temperature. In step 720, the spacing of the dies on the wafer is detected and measured. In step 730, the temperature of the wafer is measured. In step 740, refer to the database to determine the offset due to temperature changes.

In short, the accuracy and repeatability of the wafer chuck movement is extremely important for good wafer contact. Good wafer contact is repeatable and suitable When scrubbing the mark factor. "Scrub marks" are the trenches and hillocks on the exposed metal pads formed on the surface of the wafer when downward force is applied from the probe needle. These scrub marks must be on the target, but no pins are in contact with the passivation material layer around the pins that will contaminate the pins and deviate electrical measurements from their correct values. It is extremely important to reduce the size of the spacer to 30μm×30μm, and to increase the amount of probe pins and the spacing between the spacer and the spacer at each location to make the detector system accurate enough to ensure this landing. The embodiment of the probe station 1000 utilizes a custom method of multi-point XY position calibration and correction.

With reference to FIGS. 8 and 9, a method 900 for calculating the offset of a given point in the wafer area based on the measured values 1, 2 and 3 will be explained. The method uses the National Institute of Standards and Technology (NIST) traceable reference glass, as shown in Figure 8, which uses a grid of lines that can be recognized by special software routines, and the method also uses image processing and pattern recognition software libraries. Using this method 900, information about offset can be collected for thousands of data points on the wafer. Offset is the difference between where the system thinks the wafer is and where the wafer actually moves. These values are then stored in a file that will be referenced by the controller software, and these measured and known positions are then corrected for inaccuracy. According to the method 900, in step 910, a NIST traceable reference glass mask grid is provided. In step 920, information about the data points on the wafer is collected to determine the offset due to temperature changes or movement of the chuck. The offset is the difference between where the contact pad is assumed to be and where it actually moves due to temperature changes or movement of the chuck. In step 930, the X and Y coordinates on the glass mask grid are calibrated by correcting the offset determined in step 920. Perform calibration to determine the exact location of the contact pad.

Although only some embodiments of the present invention are described in detail, it should be understood that the present invention can be implemented in many other forms without departing from the scope of the present invention. It is obvious that the described wafer temperature measurement tool can be used in a wide range of applications. In view of all the above, it is obvious that the present embodiment is illustrative and not restrictive, and the present invention is not limited to the details given here, but can be used within the scope of patent application in the appendix and equivalents. Revise.