Calibration structure, corresponding calibration method and calibration device

Abstract

This invention improves the calibration structure, corresponding calibration method, and calibration device for calibrating a chuck. The calibration device is equipped with: a calibration card (6) that can be attached to or onto a socket (E) of a wafer detector (1), forming a corresponding essentially enclosed space when the calibration card (6) is attached; calibration temperature probes (60, 61) attached to the calibration card (6); and a chuck (3) for clamping a wafer (4), which can reach an input desired temperature via a temperature controller (300) and can be moved in the lateral (x, y) and vertical (z) directions via a position controller (350), and can be aligned with the calibration device via the position controller (350). A calibrated temperature probe (60, 61) is provided, which allows the calibrated temperature probe (60, 61) to measure the corresponding current temperature at different locations on the surface (O) of the chuck (3) or on the surface (O') of the wafer (4) clamped thereon; and an evaluation device (600) which is connected to the calibrated temperature probe (60, 61), a temperature controller (300), and a position controller (350) and is configured to calibrate the temperature output values ​​of one or more temperature probes (S1-S9) based on the current temperatures at different locations measured by the calibrated temperature probe (60, 61).

Description

Technical Field

[0001] This invention relates to a calibration structure, a corresponding calibration method, and a corresponding calibration apparatus for calibrating a chuck disposed in a wafer detector. Background Technology

[0002] Today, functional testing of circuits (microchips) integrated into wafers is being performed on an increasingly large scale in wafer detectors on temperature-controlled chucks between -60°C and +300°C.

[0003] Figure 7 An exemplary wafer detector structure is shown.

[0004] exist Figure 7 In the accompanying drawings, reference numeral 1 denotes a wafer detector, which includes a housing 2 having a socket E for removably inserting a test card 5. The test card 5 is sealed relative to the housing 2, for example by a sealing device 10, such that a substantially enclosed space is formed in the wafer detector 1 when the test card 5 is inserted. The test card 5 has a plurality of test probes 50 (test pins) for testing integrated circuits (not shown) located on or on the upper surface O' of a wafer 4.

[0005] A temperature-controlled chuck 3 is provided in space 2 to clamp the wafer 4 onto its upper side O. This chuck can be moved in the lateral x, y and vertical z directions via an adjustment device 30 and a position controller 350. In this example, the x, y, and z directions form an orthogonal Cartesian coordinate system.

[0006] The temperature of the chuck 3 can be regulated to a set temperature via a heating device (not shown) and a cooling device (not shown) through a temperature controller 300. Specifically, the cooling device is used to achieve a temperature below room temperature. A temperature probe S0 is disposed in the chuck 3 and is used to detect and output the current chuck temperature. The output value is sent to the temperature controller 300 and displayed via an output device 310 (e.g., a display) connected thereto. The temperature probe S0 can also be used by the temperature controller 300 for temperature regulation.

[0007] Reference numeral 700 indicates a probe controller, which is connected to the temperature controller 300, the position controller 350, and the test controller 500. The test controller is used to control the test probe 50 (test needle).

[0008] Test programs can be executed via probe controller 700 and test controller 500, with test controller 500 controlling test probe 50 with corresponding test performance according to the test program. Furthermore, probe controller 700 can specify the corresponding set temperature for temperature controller 300 and the corresponding set position for position controller 350. For example, corresponding connection lines can be established between components 5, 500, 700, 300, 310, 3, and 350 via corresponding buses and / or analog lines.

[0009] Currently, the achievable temperature accuracy for local chuck temperatures at corresponding integrated circuits is approximately 2°C or higher. However, new technologies require even higher temperature accuracy, down to below 0.1°C. This level of accuracy can only be achieved by calibrating the test setup used (chuck, wafer detector, test card).

[0010] The most common method used to address this is called a measurement wafer. This (standard silicon) measurement wafer comprises a large number of temperature sensors (typically between 13 and 17). These temperature sensors are connected to the evaluation unit. The temperature probes can therefore be calibrated. The measurement wafer sits on a chuck and displays temperature accuracy and temperature distribution.

[0011] Another approach is to place a single sensor (drop sensor) at multiple temperature measurement points. The determined values ​​are then entered (usually manually) into the temperature controller's compensation table.

[0012] The disadvantage of measurement chips is that the presence of multiple sensors or probes, which are offset from each other, limits accuracy. Similarly, such measurement chips are typically very expensive.

[0013] The disadvantages of drop sensors are the time required for measurement and the inaccuracy when placing the drop sensor on the surface of the chuck being measured.

[0014] However, a major drawback of these two methods (and all other methods known to date) is that the accuracy of the chuck temperature is determined under environmental influences different from those of the actual chip testing. In most cases, the wafer is set on the chuck far from the calibration position, and even if a drop sensor is used, it cannot be applied to subsequent measurement positions.

[0015] This means that during the microchip probing process, it is not actually possible to determine exactly where and what temperature exists under the microchip being tested. However, this is precisely the temperature value required during testing. So far, this has been accurate enough that it is considered unlikely to deviate significantly from the value determined by measuring the wafer. However, it is insufficient for the precision required today.

[0016] A calibration method and corresponding calibration apparatus for calibrating chucks are known from DE102009030471A1. A chuck for receiving and holding a test substrate is provided, having means for receiving and holding a calibration substrate. The chuck includes a first receiving surface for receiving the test substrate and a second receiving surface laterally offset from the first receiving surface for receiving the calibration substrate. The calibration substrate has a planar calibration standard for calibrating a measurement unit of a wafer detector and a dielectric material or air disposed below the calibration substrate, at least in the region of the calibration standard. To take into account the actual thermal conditions on the test substrate, and particularly on known and unknown calibration standards, and therefore the thermal effects of the electrical characteristics of the calibration standards used, a means for temperature-regulating the calibration substrate is proposed for equipping the second receiving surface. Summary of the Invention

[0017] This invention provides a calibration structure, a corresponding calibration method, and a calibration device.

[0018] Other preferred embodiments are the subject of the corresponding dependent claims.

[0019] The basic principle of the present invention is to provide a calibration device having a calibration card that can be attached to or integrated into a socket of a test card for a wafer detector, wherein when the calibration card is attached, a corresponding substantially enclosed space is formed as when the test card is inserted.

[0020] The calibration device has a calibration temperature probe attached to the calibration card, which can be approached by the chuck via the chuck's position controller, so that the calibration temperature probe can detect the corresponding current temperature at different locations on the surface of the chuck or on the surface of the wafer mounted thereon.

[0021] The calibration apparatus also includes an evaluation device that can be connected to the calibration temperature probe, temperature controller, and position controller and is configured to calibrate the temperature output values ​​of one or more temperature probes based on the current temperature detected at different locations by the calibration temperature probe.

[0022] Advantageously, chuck temperatures can be tested under the exact same environmental conditions as the actual microchips being measured later. The temperature probes in the chuck can be calibrated without removal, and the calibration of these probes can be easily and independently of those in the chuck. The manufacturing workload is significantly less than that of known measured chips. Manual repetitive errors inherent in drop sensor methods can be eliminated through automated machine contact procedures. Fully automated calibration is achieved through the integration of all components with appropriate software. The calibrated temperature probes in the chuck allow for permanent monitoring of the temperature distribution during testing. Similarly, these temperature probes in the chuck can report the actual chuck temperature to the wafer detector located beneath the corresponding chip under test in the appropriate temperature sensing area.

[0023] This invention thus achieves complete, position-dependent calibration of the chuck and enables repeatable verification of these values ​​through recalibration. Its robust design makes it suitable for industrial applications, and the components used make it economical.

[0024] According to another preferred further improvement, the temperature detection device has a single temperature probe, wherein the evaluation device is configured to calibrate the temperature output value of the single temperature probe based on the current temperature detected at different locations by the calibrated temperature probe. This achieves a particularly simple setup.

[0025] According to another preferred embodiment, the temperature detection device has multiple temperature probes, each of which is assigned a temperature detection zone in the chuck for detecting and outputting the corresponding current chuck temperature. The evaluation device is configured to calibrate the temperature output value of the corresponding temperature probe based on the current temperature of the assigned temperature detection zone detected by the calibrated temperature probe. In this way, the local chuck temperature can be recorded with particularly high precision.

[0026] According to another preferred embodiment, the temperature controller includes a storage device, wherein the evaluation device is configured to store calibrated temperature output values ​​of one or more temperature probes at different locations in the storage device.

[0027] According to another preferred embodiment, the temperature controller includes an output device, particularly a display device, for outputting calibrated temperature output values ​​of one or more temperature probes at different locations.

[0028] According to another preferred embodiment, the calibration temperature probe has a shaft passing through the calibration card, and a thermal resistor, preferably a Pt100 thermal resistor, is attached to the end of the shaft.

[0029] According to another preferred embodiment, the calibration temperature probe has a non-contact infrared sensor. This avoids direct surface contact.

[0030] According to another preferred embodiment, the measurement accuracy of the calibration temperature probe is in the range of 1 mK to 10 mK, particularly in the range of 1 mK to 5 mK, and / or the detection range of the calibration temperature probe is 10 mm. 2 Up to 20mm 2 Within a certain range. This enables very precise detection of the chuck temperature.

[0031] According to another preferred embodiment, the temperature controller is configured to control the set temperature via at least one calibrated temperature probe. This eliminates the need for a separate adjustment probe and provides precise adjustment values.

[0032] According to another preferred embodiment, the calibration card and the test card are formed as a single unit. Therefore, the same card includes both the calibration temperature probe and the test probe, and replacement cards are no longer required.

[0033] According to another preferred embodiment, the calibration temperature probe has a height-adjustable shaft that passes through the calibration card. This avoids interference between the calibration temperature probe and the test probe.

[0034] Embodiments of the present invention are shown in the accompanying drawings and described in more detail in the following description. Attached Figure Description

[0035] Figure 1a The calibration structure according to the first embodiment of the present invention is shown in its initial state.

[0036] Figure 1b A calibration structure according to a first embodiment of the present invention is shown in a calibration state.

[0037] Figure 2 A schematic planar cross-sectional view of the chuck according to the first embodiment is shown.

[0038] Figure 3 A calibration method according to a second embodiment of the present invention is shown.

[0039] Figure 4 The calibration structure according to the third embodiment of the present invention is shown in its initial state.

[0040] Figure 5 The calibration structure according to the fourth embodiment of the present invention is shown in its initial state.

[0041] Figure 6 The calibration structure according to the fifth embodiment of the present invention is shown in its initial state.

[0042] Figure 7 An exemplary wafer detector structure is shown. Detailed Implementation

[0043] In the accompanying drawings, the same reference numerals denote the same or functionally identical parts.

[0044] Figure 1a The calibration structure according to the first embodiment of the present invention is shown in its initial state before calibration, and... Figure 1b A calibration structure according to a first embodiment of the present invention is shown in a calibration state during calibration.

[0045] Figure 1a , 1b The illustration of the calibration structure according to the first embodiment shown in the figure is similar to Figure 7The wafer detector 1 is shown, therefore the calibration card 6 is installed in the socket E instead of the test card 5 with the test probe 50. Additionally, the test controller 500 is not shown because calibration is not required.

[0046] The calibration card 6 is also sealed relative to the container 2 by the sealing device 10, so that a corresponding essentially closed space is formed when the calibration card 6 is attached.

[0047] In other embodiments not shown, the calibration card 6 can also be positioned and sealed at the socket E, which is laterally spaced from the socket E.

[0048] According to the design of calibration card 6, the size of the corresponding closed space may be slightly different from the size of the closed space when test card 5 is inserted, but it is independent of the surrounding conditions of chuck 3 during calibration, so these surrounding conditions correspond to the surrounding conditions during testing.

[0049] The calibration temperature probes 60 and 61 are attached to the calibration card and can be approached by the chuck 3 via the position controller 300 in calibration mode, so that the calibration temperature probes 60 and 61 can detect the corresponding current temperature at different positions on the surface O of the chuck 3.

[0050] In the first embodiment, the calibration temperature probes 60, 61 have a shaft 60 passing through the calibration card 6, and a thermal resistor 61 in the form of a Pt100 thermal resistor is attached (e.g., elastically) to the end of the shaft 60 located in the space 2.

[0051] Calibration temperature probes 60 and 61 are connected to an evaluation device 600, which is also connected to a temperature controller 300 and a probe controller 700. The evaluation device 600 is configured to calibrate, in this embodiment, multiple temperature probes S1 to S9 disposed in the chuck 3, rather than a single temperature probe S0, based on the current temperature detected at different locations by the calibration temperature probes 60 and 61 (see [link to evaluation device]). Figure 2 The temperature output value. Similar to the test mode, the corresponding calibration mode can be controlled or input via the probe controller 700, which is similar to... Figure 7 The evaluation device 600 is connected via a network connection and / or an analog connection in the same way that the evaluation device 600 is connected to the temperature controller 300.

[0052] The temperature controller 300 also includes a non-volatile storage device 310, in which the calibrated temperature output values ​​of temperature probes S1 to S9 at different locations on the cassette 3 can be stored.

[0053] Figure 2 The chuck of the first embodiment is shown along Figure 1a , 1b A schematic planar sectional view of line A-A' in the diagram.

[0054] Figure 2 The arrangement of temperature probes S1 to S9 in chuck 3 is shown. Each temperature probe S1 to S9 is assigned a corresponding temperature detection zone B1 to B9 in chuck 3 for detecting and outputting the corresponding current chuck temperature. Output device 600 is configured to calibrate the temperature output values ​​of the corresponding temperature probes S1 to S9 based on the current temperature detected by the relevant temperature detection zones B1 to B9 of the calibration temperature probes 60 and 61, and store them in the storage device 310 of temperature controller 300.

[0055] The input set temperature, as input by the temperature controller 300, is adjusted by adjusting a probe (not shown) or by one or more calibrated temperature probes S1 to S9. Here, adjustment can be performed in each temperature sensing zone B1 to B9 using the correspondingly assigned temperature probes S1 to S9. Another possibility is to perform adjustment based on the average value of all or only the adjacent temperature probes S1 to S9.

[0056] Figure 3 A calibration method according to a second embodiment of the present invention is shown.

[0057] According to Figure 3 In the calibration method, in step S1, a socket E is provided for the wafer detector 1 for inserting a test card 5 having a test probe 50 for testing integrated circuits located on the wafer 4, wherein a substantially enclosed space is formed when the test card 5 is inserted.

[0058] In step S2, a chuck 3, which can be temperature-controlled by a temperature controller 300 to reach a set temperature, is provided to clamp the wafer 4. The chuck 3 can be moved in the lateral x, y and vertical z directions by a position controller 350.

[0059] In step S3, one or more temperature probes S1 to S9 are provided for the temperature detection device set in the chuck 3, which are used to detect and output the corresponding current chuck temperature at the position of the corresponding temperature probe S1 to S9.

[0060] In step S4, the calibration card 6 is attached to the socket E or here, wherein a corresponding essentially enclosed space is formed when the calibration card 6 is attached, wherein the calibration temperature probes 60 and 61 are attached to the calibration card 6.

[0061] In step S5, the position controller 350 brings the chuck 3 close to the calibration temperature probes 60 and 61, and the calibration temperature probes 60 and 61 detect the corresponding current temperature at different positions on the surface O of the chuck 3.

[0062] In step S6, the temperature output values ​​of one or more temperature probes S1 to S9 are calibrated based on the actual temperatures detected at different locations by the calibration temperature probes 60 and 61.

[0063] In step S7, for example, the calibrated temperature output values ​​of one or more temperature probes S1 to S9 at different locations are stored in the storage device 310 of the temperature controller 300 and / or in the probe controller 700.

[0064] Figure 4 The calibration structure according to the third embodiment of the present invention is shown in its initial state.

[0065] according to Figure 4 The third embodiment differs from the first embodiment in that, in calibration mode, the corresponding current temperature at different locations on the surface O of the chuck 3 is not determined, but when the wafer 4 is mounted on the chuck 3, the corresponding current temperature at different locations on the surface O' of the wafer 4 mounted thereon is recorded. Therefore, the temperature at the integrated circuit under test can be determined more accurately because the possible thermal resistance between the chuck 3 and the mounted wafer 4 can be taken into account.

[0066] Apart from this, the third implementation method is similar to the first implementation method.

[0067] Figure 5 The calibration structure according to the fourth embodiment of the present invention is shown in its initial state.

[0068] In the fourth embodiment, the calibration card 6 and the test card 5 are integrally formed (in other words, integrated therein). In this embodiment, the calibration temperature probes 60' and 61 have an axis 60' passing through the calibration card 6 or the test card 5, thereby allowing for height adjustment. For example, the corresponding height adjustment can be achieved by the adjustment device 69. The effect of height adjustability is that, in test mode, the calibration temperature probes 60' and 61, constructed similarly to those in the first embodiment, do not interfere with the test probe 50, but can retract upwards and align behind them.

[0069] A particular advantage of this implementation is that it does not require replacing the test card 5 and calibration card 6, but only requires switching from test mode to calibration mode via the probe controller 700.

[0070] Figure 6 The calibration structure according to the fifth embodiment of the present invention is shown in its initial state.

[0071] In the fifth embodiment, the calibration card 6 is also integrally formed as a single piece with the test card 5. In this embodiment, the calibration temperature probe 65 is a non-contact infrared sensor 65 connected to the evaluation device 600. Therefore, direct surface contact with the surface O' of the wafer 4 or the surface O of the chuck 3 can be avoided, and the height adjustment method used in the fourth embodiment can be omitted.

[0072] An additional advantage of this is that calibration or temperature measurement can also be performed in situ during testing by calibrating the temperature probe 65.

[0073] Apart from this, the fifth implementation is similar to the fourth implementation.

[0074] Although the present invention has been described above with reference to preferred embodiments, it is not limited thereto and can be modified in various ways.

[0075] In particular, the number and arrangement of temperature probes in the chuck, as well as their types, are merely exemplary and not limited to the examples shown.

Claims

1. A calibration structure for calibrating a chuck, comprising: a wafer probe (1) having a socket (E) for inserting a test card (5) having test probes (50) for testing integrated circuits located on a wafer (4), wherein a closed space is formed when the test card (5) is inserted; a chuck (3) for clamping the wafer (4), which is temperature-controllable by a temperature controller (300) to a settable set temperature, wherein the chuck (3) is movable by a position controller (350) in lateral directions (x, y) and in a height direction (z); a temperature detection device having one or more temperature probes (S1-S9) arranged in the chuck (3) for detecting and outputting a respective current chuck temperature at the location of the respective temperature probe (S1-S9); and a calibration device (6, 60, 61, 600) comprising: a calibration card (6) attached to or in the socket (E), wherein a corresponding closed space is formed when the calibration card (6) is attached; a calibration temperature probe (60, 61; 60', 61; 65) attached to the calibration card (6), which is accessible by the chuck (3) by means of the position controller (350) such that the calibration temperature probe (60, 61; 60', 61; 65) can detect a respective current temperature at different locations on a surface (O) of the chuck (3) or of the wafer (4) mounted thereon; and an evaluation device (600) connected to the calibration temperature probe (60, 61; 60', 61; 65), to the temperature controller (300) and to the position controller (350) and set up to calibrate the temperature output values of one or more of the temperature probes (S1-S9) based on the current temperatures detected at the different locations by the calibration temperature probe (60, 61; 60', 61; 65).

2. The calibration structure of claim 1, wherein, The temperature detection device comprises a single temperature probe, and wherein the evaluation device (600) is set up to calibrate the temperature output values of the single temperature probe based on the current temperatures detected at the different locations by the calibration temperature probe (60, 61; 60', 61; 65).

3. The calibration structure of claim 1, wherein, The temperature detection device has a plurality of temperature probes (S1-S9), wherein each of the temperature probes (S1-S9) is assigned a temperature detection zone (B1-B9) in the chuck (3) for detecting and outputting a respective current chuck temperature, and wherein the evaluation device (600) is set up to calibrate the temperature output values of the respective temperature probes (S1-S9) based on the current temperatures of the assigned temperature detection zones (B1-B9) detected by the calibration temperature probe (60, 61; 60', 61; 65).

4. The calibration structure according to any one of claims 1 to 3, wherein, The temperature controller (300) comprises a storage device (310), and wherein the evaluation device (600) is configured to store in the storage device (310) the calibrated temperature output values of one or more of the temperature probes (S1-S9) at different positions.

5. The calibration structure according to any one of claims 1 to 3, wherein, The temperature controller (300) comprises an output device (320) for outputting the calibrated temperature output values of one or more of the temperature probes (S1-S9) at different positions.

6. The calibration structure of claim 5, wherein, The output device is a display device.

7. The calibration structure according to any one of claims 1 to 3, wherein, The calibration temperature probe (60, 61; 60', 61; 65) has a shaft (60) which passes through the calibration card (6), at the end of which a thermal resistance (61) is attached.

8. The calibration structure of claim 7, wherein, The thermal resistance is a Pt100 thermal resistance.

9. The calibration structure according to any one of claims 1 to 3, wherein, The calibration temperature probe (60, 61; 60', 61; 65) comprises a non-contact infrared sensor.

10. The calibration structure according to any one of claims 1 to 3, wherein, The measurement accuracy of the calibration temperature probe (60, 61; 60', 61; 65) is in the range of 1 mK to 10 mK and / or the area detection range of the calibration temperature probe (60, 61; 60', 61; 65) is in the range of 10 mm 2 to 20 mm 2 .

11. The calibration structure according to any one of claims 1 to 3, wherein, The calibration temperature probe (60, 61; 60', 61; 65) has a measurement accuracy in the range of 1 mK to 5 mK.

12. The calibration structure according to any one of claims 1 to 3, wherein, The temperature controller (300) is configured to adjust the set temperature by at least one calibrated temperature probe (S1-S9).

13. The calibration structure according to any one of claims 1 to 3, wherein, The calibration card (6) is integrally formed with the test card (5) as a single piece.

14. The calibration structure of claim 12, wherein, The calibration temperature probe (60, 61; 60', 61; 65) comprises a shaft (60') which passes through the calibration card (6) in a height-adjustable manner.

15. A calibration method for a chuck, comprising the following steps: providing (S1) a wafer probe (1) having a socket (E) for inserting a test card (5) having test probes (50) for testing integrated circuits located on a wafer (4), wherein a closed space is formed when the test card (5) is inserted; providing (S2) a chuck (3) for clamping the wafer (4), which can be temperature-controlled by a temperature controller (300) to a settable set temperature, wherein the chuck (3) can be moved in lateral directions (x, y) and in a height direction (z) by a position controller (350); providing (S3) a temperature detection device having one or more temperature probes (S1-S9) arranged in the chuck (3) for detecting and outputting a respective current chuck temperature at the position of the respective temperature probe (S1-S9); attaching (S4) a calibration card (6) to or in the socket (E), wherein a corresponding closed space is formed when the calibration card (6) is attached, wherein a calibration temperature probe (60, 61; 60', 61; 65) is attached to the calibration card (6); approaching (S5) the calibration temperature probe (60, 61; 60', 61; 65) by the chuck (3) by means of the position controller (350) and detecting a respective current temperature at different positions on a surface (O) of the chuck (3) or of a wafer (4) mounted thereon by means of the calibration temperature probe (60, 61; 60', 61; 65); and calibrating (S6) temperature output values of one or more of the temperature probes (S1-S9) based on current temperatures detected by the calibration temperature probes (60, 61; 60', 61; 65) at different positions.

16. The calibration method of claim 15, wherein, storing (S7) calibrated temperature output values of one or more of the temperature probes (S1-S9) at different positions.

17. The calibration method of claim 15 or 16, wherein, adjusting the set temperature by at least one of the calibrated temperature probes (S1-S9).

18. A calibration device (6, 60, 61, 600) for calibrating a chuck, comprising: a calibration card (6) attachable to or attached in a socket (E) of a wafer prober (1), wherein a corresponding closed space is formed when the calibration card (6) is attached; calibration temperature probes (60, 61; 60', 61; 65) attached to the calibration card (6) and accessible by a chuck (3) that can be used for mounting a wafer (4), the chuck (3) being temperature controllable by a temperature controller (300) to a settable set temperature, the chuck being movable in lateral directions (x, y) and in a height direction (z) by a position controller (350), the calibration temperature probes (60, 61; 60', 61; 65) being enabled by the position controller (350) to detect respective current temperatures at different positions on a surface (O) of the chuck (3) or of the wafer (4) mounted thereon; and an evaluation device (600) connectable to the calibration temperature probes (60, 61; 60', 61; 65), the temperature controller (300) and the position controller (350) and arranged to calibrate temperature output values of one or more temperature probes (S1-S9) based on current temperatures detected by the calibration temperature probes (60, 61; 60', 61; 65) at different positions.

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