Test equipment

Abstract

The present invention provides a test device (100) for electrically testing an integrated circuit on a wafer (102). The test device (100) comprises: a vacuum chamber (109); a chuck (101), the chuck (101) being used to hold the wafer (102); a probe card (103), the probe card (103) being used to electrically contact the integrated circuit; and a radiation shield (107), the radiation shield (107) being arranged inside the vacuum chamber (109) and encapsulating the chuck (101) and the probe card (103). In the test device (100), the vacuum chamber (109) is provided with a gate valve (123), the radiation shielding member (107) is provided with a cabin door (122), and the test device (100) includes a wafer loading assembly (125), and the wafer loading assembly (125) is used to load the wafer (102) onto the chuck (101) through the gate valve (123) and the cabin door (122).

Description

Technical Field

[0001] The invention relates to a testing device as described in the preamble of the accompanying independent claim. Background Art

[0002] Semiconductor device manufacturing is a common process for creating integrated circuits on wafers made of semiconductor materials using a multi-step sequence of photolithography and chemical processing steps. As part of the process, the integrated circuits created on the wafer are usually tested for functional defects by applying special test patterns to them. This testing is performed using a test device called a wafer prober.

[0003] Examples of known wafer probers include a chuck for holding a wafer to be tested and a probe card for electrically contacting the integrated circuits on the wafer. The probe card is electrically connected to an electronic test unit, which performs electrical tests on the integrated circuits according to a test program. The test program defines the content of the test patterns and the sequence in which they are applied to the integrated circuits. The chuck and the probe card are arranged inside the chamber, which allows the integrated circuits to be tested in a controlled environment. For electrical testing, the probe card is held in place while the wafer mounted on the chuck is moved between test positions. In each test position, the contact elements of the probe card are arranged to electrically contact the contact pads of a group of integrated circuits, which are then electrically tested by the electronic test unit.

[0004] A problem associated with known wafer probers is that loading a wafer onto a chuck is difficult and time consuming because the conditions in the chamber (such as temperature, pressure and humidity) can change significantly during wafer loading. Restoring the conditions in the chamber after a wafer has been loaded takes time and consumes energy, especially if the integrated circuits on the wafer need to be tested at very low temperatures (such as less than 4K). Summary of the invention

[0005] The main object of the present invention is to reduce or even eliminate the prior art problems presented above.

[0006] An object of the present invention is to provide a test apparatus for electrical testing of integrated circuits on a wafer. In more detail, an object of the present invention is to provide a test apparatus capable of loading and unloading a wafer onto and from a chuck of the test apparatus with minimal change in conditions inside the test apparatus. Another object of the present invention is to provide a test apparatus capable of quickly and easily loading and unloading a wafer onto and from a chuck of the test apparatus.

[0007] In order to achieve the above objects, the testing device according to the invention is characterized by what is presented in the characterizing part of the attached independent claim. Advantageous embodiments of the invention are described in the dependent claims.

[0008] Description of the invention

[0009] A test device according to the present invention comprises: a vacuum chamber; a chuck for holding a wafer including an integrated circuit; a probe card for electrically contacting the integrated circuit on the wafer; and a radiation shielding member arranged inside the vacuum chamber and encapsulating the chuck and the probe card. In the test device according to the present invention, the vacuum chamber is provided with a gate valve, the radiation shielding member is provided with a hatch, and the test device comprises a wafer loading assembly for loading the wafer onto the chuck through the gate valve and the hatch.

[0010] The test device according to the present invention can be used to perform electrical tests on integrated circuits on a wafer. This test device can be called a wafer prober. In the test device according to the present invention, the wafer to be tested is loaded onto a chuck together with a wafer loading assembly, and the chuck moves between test positions. In each test position, the probe card makes electrical contact with one or more integrated circuits, and then the one or more integrated circuits can be electrically tested.

[0011] The chuck is used to hold the wafer during testing of the integrated circuit. The chuck can be, for example, a mechanical chuck including a plurality of heat conducting pins for holding the wafer on a substrate of the chuck. Alternatively, the chuck can be, for example, an electrostatic chuck including a metal substrate coated with a layer of dielectric material. By providing a voltage difference between the metal substrate and the wafer, electrostatic forces hold the wafer on the chuck. In order to maintain the flatness of the wafer and promote the rapid transfer of heat from the wafer, the chuck is preferably made of a heat conducting material such as copper or gold. The chuck can be made of gold-plated copper. These materials provide good thermal properties and performance.

[0012] The probe card is used to electrically contact the integrated circuits on the wafer. The probe card may include a printed circuit board (PCB) and one or more contact elements that may be arranged to make electrical contact with the contact pads of the integrated circuits. The test equipment may include a camera for optically locating the contact elements on the probe card and the contact pads on the wafer. By using this information, the contact pads of the integrated circuit to be tested may be aligned with the contact elements of the probe card.

[0013] The probe card may be attached to a probe card holder, which is attached to the radiation shield. Depending on the shape and form of the contact elements, the probe card may be, for example, a needle-type, vertical pin-type, or MEMS (micro-electromechanical system) type probe card. The contact elements of the probe card may be made, for example, of tungsten or a tungsten / rhenium alloy. The contact pads of the integrated circuit may be made, for example, of aluminum, copper, a copper alloy, or many types of solders, such as lead-tin and tin-silver. Typically, the probe card is customized for each type of wafer so that each integrated circuit on the wafer can be electrically tested.

[0014] The chuck and the probe card are arranged inside the radiation shield. The radiation shield acts as a thermal shield, thereby reducing the heat transfer. In other words, the radiation shield is a thermal radiation shield. The radiation shield defines a substantially enclosed space in which the chuck and the probe card are placed. The radiation shield may be composed of one or more shielding parts. The radiation shield may be mechanically attached to the vacuum chamber or another radiation shield encapsulating the vacuum chamber, but thermally isolated therefrom. The radiation shield may include a cylindrical sidewall, an upper end wall attached to the upper edge of the sidewall around its periphery, and a lower end wall attached to the lower edge of the sidewall around its periphery. The radiation shield may be made of aluminum, for example.

[0015] Radiative heat transfer (emission / absorption) can be reduced by making the surfaces of the radiation shield and the inner surfaces of the vacuum chamber reflective. The heat reflective surface can be, for example, a polished metal. By making the surface locally heat absorbing, the proportion of the heat reflective surface can be maximized and only non-idealities in the geometry (such as gaps) can be compensated. The heat absorbing surface can be, for example, black anodized or painted black.

[0016] The hatch is attached to a wall (preferably a side wall) of the radiation shield. The hatch is preferably thermally anchored to the radiation shield by aluminum or copper cables. The hatch is arranged in the wall of the radiation shield in connection with the opening. The hatch can be moved between a closed position and an open position. In the closed position, the hatch closes the opening in the wall of the radiation shield so that radiation is blocked. In the open position, the wafer can be loaded onto or unloaded from the chuck. Preferably, the hatch is arranged to open only inwardly. The hatch is preferably rectangular. The hatch is preferably made of the same material as the radiation shield.

[0017] A vacuum chamber allows testing of integrated circuits in a controlled environment. Various devices may be used to control conditions (such as pressure and temperature) inside the vacuum chamber. The testing equipment may include, for example, a vacuum pump connected to the vacuum chamber for controlling the pressure and a cooling unit connected to the vacuum chamber for controlling the temperature inside the vacuum chamber. The vacuum chamber may, for example, be made of stainless steel or aluminum. When testing integrated circuits, the pressure inside the vacuum chamber is typically less than 10E-4 mbar.

[0018] The gate valve is attached to a wall (preferably a side wall) of the vacuum chamber. The gate valve is arranged in the wall of the vacuum chamber in connection with an opening. The gate valve can be closed or opened. When the gate valve is closed, the interior of the vacuum chamber is isolated from the surrounding environment. When the gate valve is open, a wafer can be loaded onto or unloaded from the chuck.

[0019] A gate valve may include a circular or rectangular gate that can be moved by an actuator that is attached to the gate by a threaded rod. The gate valve opens by lifting the gate. The sealing surface between the gate and the valve seat is usually flat. The gate valve may be all-metal and, for example, made of stainless steel.

[0020] The wafer is loaded onto the chuck by the wafer loading assembly. The wafer loading assembly moves the wafer onto the chuck through the gate valve and the hatch as follows. First, the gate valve is opened and the wafer is moved inside the vacuum chamber, and then the hatch is opened and the wafer is moved inside the radiation shield and placed onto the chuck. The wafer loading assembly can also be used to unload the wafer from the chuck.

[0021] The test equipment may include a device for moving the chuck relative to the probe card. The moving device may include an actuator for moving the chuck in three perpendicular directions and another actuator for rotating the chuck around an axis. The actuator is preferably arranged outside the radiation shield or even outside the vacuum chamber so that the heat generated by the actuator does not heat the space where the test integrated circuit is located, that is, the inside of the radiation shield. The moving device may include a support column having a first end and a second end. The first end of the support column may be attached to the chuck, and the second end of the support column may be attached to the actuator. The movement generated by the actuator is therefore transmitted to the chuck through the support column. The support column may be made of metal (such as stainless steel) or other materials with good mechanical properties and low thermal conductivity. The support column may be a single-piece or multi-piece pipe that can be made of sheet metal. The wall thickness of the pipe can be in the range of 0.05mm to 0.3mm, which ensures that the heat transferred through the support column is minimal, while the support column is hard enough to maintain its shape.

[0022] The test equipment may include an electronic test unit for electrically testing the integrated circuits on the wafer. The electronic test unit is electrically connected to a probe card. Preferably, the electronic test unit is arranged outside the vacuum chamber. The probe card provides an electrical path between the electronic test unit and the integrated circuits on the wafer, thereby allowing the integrated circuits to be tested and verified. The electronic test unit tests the integrated circuits according to a test program that defines the content of the test patterns and the sequence in which they are applied to the integrated circuits. The electronic test unit may include a processor and a memory including a computer program code, the memory and the computer program code being configured to cause the electronic test unit to electrically test the integrated circuits using the processor.

[0023] An advantage of the test apparatus according to the invention is that wafers can be loaded onto and unloaded from the chuck with minimal change to the conditions in the space where the test integrated circuit is located (i.e. inside the radiation shield). Another advantage of the test apparatus according to the invention is that wafers can be quickly and easily loaded onto and unloaded from the chuck.

[0024] According to an embodiment of the present invention, the wafer loading assembly includes: a loading chamber, the loading chamber is attached to the vacuum chamber in connection with the gate valve; a loading arm, the loading arm includes an end actuator for carrying the wafer; and an actuator, the actuator is used to move the end actuator between the loading chamber and the chuck. The loading chamber and the vacuum chamber are connected to each other through the gate valve. The loading chamber may include a channel door, through which the wafer can be placed on the end actuator or removed from the end actuator. The end actuator can be, for example, a planar fork plate that carries the wafer from the bottom. The loading arm may include a rod, and the end actuator is attached to the end of the rod. The actuator can be connected to the rod and is configured to move the rod in its longitudinal direction. The actuator can be, for example, a ball screw drive actuated by a motor. The actuator may include a linear movement mechanism connected to the rod. The rod passes through the loading chamber wall, and the through hole is hermetically sealed.

[0025] The wafer can be loaded onto the chuck as follows. First, the wafer is placed onto the end effector located inside the loading chamber. The gate valve is kept closed until the placement of the wafer has been completed and the desired conditions inside the loading chamber have been achieved. Next, the gate valve is opened and the end effector is moved inside the vacuum chamber and further through the hatch inside the radiation shield. As the end effector moves into the radiation shield, the hatch can be pushed open by the end effector, or the hatch can be opened by a separate mechanism. Finally, the wafer is transferred from the end effector to the chuck, and then the end effector is moved back into the loading chamber and the gate valve is closed.

[0026] According to an embodiment of the present invention, the hatch includes a first thermal contact area and the end effector includes a second thermal contact area for conducting heat from the end effector to the hatch when the end effector contacts the hatch. The first thermal contact area is arranged on the outside of the hatch. The first thermal contact area and the second thermal contact area can be made of copper. The advantage of the first thermal contact area and the second thermal contact area is that the end effector and the wafer placed on the end effector can be cooled before moving them to the inside of the radiation shield. The longer the first thermal contact area is in contact with the second thermal contact area, the greater the extent to which the end effector and the wafer can be cooled.

[0027] According to an embodiment of the invention, the hatch is hinged to the radiation shield at its upper end. Preferably, the hatch is arranged in such a way that it closes the opening in the radiation shield when it is in a vertical position. In this case, the hatch automatically closes the opening due to gravity. The hatch can be opened by pushing the hatch with an end effector. Alternatively, the hatch can be opened by a separate mechanism.

[0028] According to an embodiment of the invention, the hatch comprises a spring for closing the hatch. The spring ensures that the hatch is correctly closed.

[0029] According to an embodiment of the present invention, the test device includes a cooling unit thermally connected to the radiation shield. In this article, the expression "thermally connected" means that two components are connected so that heat can be conducted between them. The cooling unit is used to cool the interior of the radiation shield to the desired test temperature and to maintain the test temperature during the test of the integrated circuit. The test temperature in the radiation shield can be, for example, in the range of 1-4K. Heat is transferred from the radiation shield by one or more thermal couplings connected between the radiation shield and the cooling unit. The thermal coupling can be, for example, a cable or a rod made of copper or aluminum.

[0030] According to an embodiment of the present invention, a cooling unit is thermally connected to a chuck and a probe card. The cooling unit is used to cool the chuck and the probe card. When the chuck is cooled by the cooling unit, the heat from the wafer mounted on the chuck can be transferred to the chuck by conduction. Correspondingly, when the probe card is cooled by the cooling unit, the heat from the wafer can be transferred to the probe card when the probe card is in electrical contact with the integrated circuit. The heat is transferred by conduction through the contact pads of the integrated circuit and the contact elements of the probe card. Therefore, the cooling unit can efficiently cool the wafer through the chuck and the probe card.

[0031] The cooling unit may have a plurality of temperature stages. Preferably, the chuck and the probe card are thermally connected to a temperature stage that provides a lower temperature than the temperature stage that is thermally connected to the radiation shield. The temperature provided by the temperature stage may, for example, be in the range of 0.8-1.2K, or about 1K. Heat is transferred away from the chuck via one or more thermal couplings connected between the chuck and the cooling unit. Heat is transferred away from the probe card via one or more thermal couplings connected between the probe card and the cooling unit. Preferably, the cooling unit is thermally connected to the probe card via a probe card holder. The thermal coupling may be, for example, a cable or rod made of copper or aluminum. The advantage of using a cooling unit to cool the chuck and the probe card is that the wafer can be cooled to the desired test temperature more quickly and more energy efficiently.

[0032] According to an embodiment of the present invention, the cooling unit is a dry cryostat using a closed-loop helium cycle. When a dry cryostat is used, the vacuum chamber is kept at room temperature (not in a liquid nitrogen or liquid helium bath), and all cryogenic components are located inside the vacuum chamber. The dry cryostat may include multiple temperature stages, for example, a 50K stage, a 4K stage, and a 1K stage. The advantage of a dry cryostat is that the wafer can be cooled to a temperature below 4K without immersing the entire system in a liquid helium bath.

[0033] According to an embodiment of the present invention, the test device includes a plurality of nested radiation shields arranged inside the vacuum chamber, each of the nested radiation shields being provided with a hatch through which the wafer can be loaded onto the chuck. The number of radiation shields may be, for example, 2, 3, 4, or more than 4. The chuck and the probe card are arranged inside the innermost radiation shield. The advantage of the plurality of nested radiation shields is the improved thermal shielding of the test device, whereby the desired test temperature inside the innermost radiation shield can be achieved and maintained with a minimum amount of energy compared to a test device having only one radiation shield.

[0034] According to an embodiment of the present invention, the cooling unit has a plurality of temperature levels that are thermally connected to different radiation shields. The temperature levels of the cooling unit are configured to provide different temperatures to the radiation shield. The temperature level that provides the lowest temperature is thermally connected to the innermost radiation shield, the temperature level that provides the second lowest temperature is thermally connected to the second innermost radiation shield, and so on. By using the temperature level, the innermost radiation shield can be cooled to a temperature in the range of 3-5K or about 4K, and the second innermost radiation shield can be cooled to a temperature in the range of 45-55K or about 50K. Heat is transferred from the radiation shield by one or more thermal couplings connected between the temperature level and the radiation shield. The thermal coupling can be, for example, a cable or rod made of copper or aluminum. The advantage of a cooling unit with multiple temperature levels is that the space where the test integrated circuit is located (i.e., the inside of the innermost radiation shield) can be cooled to the desired test temperature more quickly and more efficiently with energy.

[0035] According to an embodiment of the present invention, the chuck includes a plurality of heat transfer pins for holding the wafer on a substrate of the chuck. The heat transfer pins transfer heat from the wafer to the chuck. The chuck can be thermally connected to a cooling unit for transferring heat away from the chuck. The number of heat transfer pins can be, for example, 3, 4, 5 or more than 5. The heat transfer pins can be, for example, made of copper. The substrate is made of a heat conductive material such as copper or gold or gold-plated copper, which enables heat to be efficiently transferred from the wafer to the substrate.

[0036] According to an embodiment of the invention, the thermally conductive pins are attached to the periphery of the substrate.Thus, the thermally conductive pins are arranged to contact the outer edge of the wafer in order to hold the wafer on the substrate.

[0037] According to an embodiment of the invention, at least one of the heat transfer pins is attached to the periphery of the substrate by a spring, the spring being movable in the plane of the substrate. The spring operated pin can be moved together with an end effector, which loads the wafer onto the chuck. The spring ensures good contact between the wafer and the heat transfer pin, and thus improves heat transfer from the wafer to the chuck.

[0038] According to an embodiment of the present invention, the outer end of the heat transfer pin has a frustoconical shape so as to be able to press the wafer against the substrate. The frustoconical shape ensures good contact between the wafer and the heat transfer pin and the substrate, and thus improves heat transfer from the wafer to the chuck.

[0039] The exemplary embodiments of the invention presented herein are not to be construed as limiting the applicability of the appended claims. The verb "comprise" is used herein as an open limitation, which does not exclude the presence of unrecited features. Unless expressly stated otherwise, the features recited in the dependent claims can be freely combined with each other. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1A to Figure 1B The wafer is shown loaded into the test equipment according to an embodiment of the present invention, and

[0041] FIG. 2A to FIG. 2B An exemplary chuck is shown. DETAILED DESCRIPTION

[0042] In different embodiments, the same or similar components are provided with the same reference numerals.

[0043] Figure 1A to Figure 1B Loading of a wafer into a test apparatus is shown in accordance with an embodiment of the present invention. Figure 1A Show ratio Figure 1B A more detailed cross-sectional view of the test equipment.

[0044] The test apparatus 100 includes a chuck 101 for holding a wafer 102 including integrated circuits and a probe card 103 attached to a probe card holder 104 for electrically contacting the integrated circuits on the wafer 102. The probe card 103 includes contact elements 105 that can be arranged to make electrical contact with contact pads of the integrated circuits. Electrical testing of the integrated circuits is accomplished using an electronic test unit 106 that is electrically connected to the probe card 103. The probe card 103 provides an electrical path between the electronic test unit 106 and the integrated circuits on the wafer 102.

[0045] The test apparatus 100 includes two nested radiation shields 107 and 108, which are arranged inside a vacuum chamber 109. The chuck 101 and the probe card 103 are arranged inside the innermost radiation shield 107. The vacuum chamber 109 allows the integrated circuit to be tested in a controlled environment. The pressure inside the vacuum chamber 109 is controlled by a vacuum pump 110.

[0046] The chuck 101 can be moved relative to the probe card 103 using a moving device including a support column 111 having a first end and a second end. The first end of the support column 111 is attached to the chuck 101 so that the chuck 101 is perpendicular to the longitudinal axis of the support column 111. The moving device also includes an actuator 112 for moving the support column 111 in three perpendicular directions and an actuator 113 for rotating the support column 111 around its longitudinal axis. The actuators 112 and 113 are attached to the second end of the support column 111 so that the movement is transmitted to the chuck 101 through the support column 111. The support column 111 is arranged to pass through the walls of the radiation shields 107 and 108 so that the first end of the support column 111 extends into the interior of the radiation shield 107 and the second end of the support column 111 extends out of the radiation shield 108.

[0047] The test apparatus 100 includes a cooling unit 114 for cooling the wafer 102 to a desired test temperature and for maintaining the test temperature during testing of the integrated circuit. The cooling unit 114 includes three temperature levels 115, 116, and 117, each of which is configured to provide a specific temperature to a part to which the cooling unit is thermally connected. The first temperature level 115 is thermally connected to the chuck 101 and the probe card 103. The temperature achievable with the first temperature level 115 is lower than the temperature achievable with the second temperature level 116 and the third temperature level 117. Heat is transferred away from the chuck 101 through a thermal coupling 118 connected between the first temperature level 115 and the chuck 101. Heat is transferred away from the probe card 103 through a thermal coupling 119 connected between the first temperature level 115 and the probe card holder 104. The second temperature level 116 is thermally connected to the radiation shield 107, and the third temperature level 117 is thermally connected to the radiation shield 108. The temperature achievable with the second temperature level 116 is lower than the temperature achievable with the third temperature level 117. Heat is transferred away from the radiation shield 107 through a thermal coupling 120 connected between the second temperature stage 116 and the radiation shield 107. Heat is transferred away from the radiation shield 108 through a thermal coupling 121 connected between the third temperature stage 117 and the radiation shield 108.

[0048] Each of the radiation shields 107 and 108 is provided with a hatch 122 attached to the side walls of the radiation shields 107, 108. The hatch 122 is hinged to the radiation shields 107, 108 at its upper end and is arranged in such a way that the hatch 122 can only be opened inwardly. The hatch 122 is movable between a closed position and an open position. In the closed position, the hatch 122 closes the opening in the wall of the radiation shield 107, 108 so that radiation is blocked. In the open position, the wafer 102 can be loaded onto or unloaded from the chuck 101. The hatch 122 is arranged in such a way that the hatch 122 automatically closes the opening due to gravity.

[0049] The vacuum chamber 109 is provided with a gate valve 123. The gate valve 123 is attached to the side wall of the vacuum chamber 109 in connection with the opening. The gate valve 123 includes a gate 124 that can move up and down to open and close the opening. When the gate valve 123 is closed, the interior of the vacuum chamber 109 is isolated from the surrounding environment. When the gate valve 123 is opened, the wafer 102 can be loaded onto or unloaded from the chuck 101.

[0050] The test apparatus 100 includes a wafer loading assembly 125 for loading a wafer 102 onto a chuck 101 through a gate valve 123 and a hatch 122. The wafer loading assembly 125 includes a loading chamber 126 attached to a vacuum chamber 109 in connection with the gate valve 123. The loading chamber 126 and the vacuum chamber 109 are in communication with each other through the gate valve 123. The wafer loading assembly 125 also includes a loading arm 127 including an end effector 128 for carrying the wafer 102 and an actuator 129 for moving the end effector 128 between the loading chamber 126 and the chuck 101. The loading arm 127 includes a rod 130 to the end of which the end effector 128 is attached. The actuator 129 is connected to the rod 130 and is configured to move the rod 130 in a longitudinal direction thereof.

[0051] Wafer 102 is loaded onto chuck 101 as follows. First, Figure 1AAs shown, the wafer 102 is placed onto the end effector 128 located inside the loading chamber 126. The gate valve 123 is kept closed until the placement of the wafer 102 has been completed and the desired conditions inside the loading chamber 126 have been achieved. Next, the gate valve 123 is opened, and the end effector 128 is moved inside the vacuum chamber 109 and further through the hatch 122 inside the radiation shield 107. As the end effector 128 moves toward the chuck 101, the hatch 122 is pushed open by the end effector 128. Each hatch 122 includes a thermal contact area 131 and the end effector 128 includes a thermal contact area 132 for conducting heat from the end effector 128 to the hatch 122 when the end effector 128 contacts the hatch 122. Each hatch 122 is thermally connected to the radiation shield 107 or 108 by a thermal coupling 133. Finally, as shown in FIG. Figure 1B As shown, the wafer 102 is transferred from the end effector 128 to the chuck 101 .

[0052] FIG. 2A to FIG. 2B An exemplary chuck for holding a wafer is shown. Figure 2A A top view of the chuck is shown and Figure 2B 1 shows a side view of the chuck. The chuck 101 includes three heat transfer pins 201, 202 and 203, which are used to hold the wafer 102 on the substrate 204 and to conduct heat from the wafer 102 to the substrate 204. The heat transfer pins 201, 202 and 203 are attached to the periphery of the substrate 204 so that the heat transfer pins 201, 202 and 203 can contact the outer edge of the wafer 102 to hold the wafer 102 on the substrate 204. The outer ends of the heat transfer pins 201, 202 and 203 have a truncated cone shape so that the wafer 102 can be pressed against the substrate 204. The heat transfer pins 203 are attached to the periphery of the substrate 204 by springs 205. The springs 205 are movable in the plane of the substrate 204. The spring operating pins 203 can be connected with the end actuator ( FIG. 2A to FIG. 2B The end effector moves together with the wafer 102 (not shown), and the end effector loads the wafer 102 onto the chuck 101.

[0053] Only advantageous exemplary embodiments of the invention are described in the drawings. It is clear to the person skilled in the art that the invention is not limited to the examples presented above, but that the invention may vary within the limits of the claims presented below. Some possible embodiments of the invention are described in the dependent claims, and they are not to be regarded as limiting the scope of protection of the invention in this way.

Claims

1. A testing device, comprising: - Vacuum chamber, - a chuck for holding a wafer comprising an integrated circuit, - a probe card for electrically contacting the integrated circuits on the wafer, and - a radiation shield arranged inside the vacuum chamber and enclosing the chuck and the probe card, Features: - the vacuum chamber is provided with a gate valve, - the radiation shield is provided with a hatch, - the testing device comprises a wafer loading assembly, the wafer loading assembly is used to load the wafer onto the chuck through the gate valve and the hatch, -The wafer loading assembly comprises: - a loading chamber attached to the vacuum chamber in connection with the gate valve, a loading arm comprising an end effector for carrying the wafer, and - an actuator for moving the end effector between the loading chamber and the chuck, -The chuck comprises a plurality of heat transfer pins for holding the wafer on a base plate of the chuck, wherein at least one of the heat transfer pins is attached to the periphery of the base plate by a spring, the spring being movable in the plane of the base plate, wherein the heat transfer pins attached to the periphery of the base plate by the spring are movable together with the end effector, which loads the wafer onto the chuck.

2. The test device according to claim 1, characterized in that The hatch includes a first thermal contact area and the end effector includes a second thermal contact area for conducting heat from the end effector to the hatch when the end effector contacts the hatch.

3. The testing device according to claim 1 or 2, characterized in that The hatch is hinged at its upper end to the radiation shield.

4. The testing device according to claim 1 or 2, characterized in that: The door includes a spring for closing the door.

5. The testing device according to claim 1 or 2, characterized in that: The testing apparatus includes a cooling unit thermally connected to the radiation shield.

6. The testing device according to claim 5, characterized in that: The cooling unit is thermally connected to the chuck and the probe card.

7. The testing device according to claim 5, characterized in that: The cooling unit is a dry cryostat using a closed loop helium gas cycle.

8. The testing device according to claim 5, characterized in that The testing apparatus comprises a plurality of nested radiation shields arranged inside the vacuum chamber, each of the nested radiation shields being provided with a hatch through which the wafer can be loaded onto the chuck.

9. The testing device according to claim 8, characterized in that: The cooling unit has multiple temperature stages thermally connected to different radiation shields.

10. The testing device according to claim 1, characterized in that: The thermally conductive pins are attached to a periphery of the base plate.

11. The testing device according to claim 1, characterized in that The outer ends of the heat transfer pins have a frusto-conical shape so as to be able to press the wafer against the substrate.

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