Method for open or closed loop control of wafer chuck temperature and wafer test system - Patent Application 20070122997

Abstract

The present invention relates to a method for open-loop or closed-loop control of the temperature of a chuck for a wafer, the method including the steps of detecting the position of a testing means for testing a wafer, determining a spatial distance between the testing means and a plurality of temperature measurement means for measuring the temperature of the chuck or a wafer supported or clamped by the chuck, selecting at least one temperature measurement means of the plurality of temperature measurement means as a reference temperature measurement means, and controlling the temperature of the chuck by open-loop or closed-loop control based on the temperature of the chuck or wafer measured by the selected reference temperature measurement means or means.

Description

[Background technology]

[0001] Chucks are used, for example, in the semiconductor industry, particularly in microelectronics and microsystems technology, to provide wafers for testing, for example, their geometric parameters. Furthermore, structures (electrical components, such as diodes, transistors, and integrated circuits) arranged on the wafer can be contacted with test means (probes) to perform various functional tests. Functional tests, for example, involve applying a voltage and / or current to the structures and measuring specific parameters. In such functional tests, it is particularly advantageous for the wafer or structures to be tested to have a specific temperature at the start of the test. This has the particular advantage of reducing or substantially avoiding influences that interfere with the test. Furthermore, the temperature of the structure or wafer typically changes due to interaction with the test means (prober), particularly upon contact between the structure and the prober, and due to the flow of current during the functional test. Therefore, it is advantageous to continuously temperature-control or control or adjust the temperature of the structure or wafer so that, preferably, substantially identical test conditions prevail during the functional test. The temperature range in which functional tests are performed typically ranges from about -75°C to about 400°C.

[0002] Multiple temperature sensors and temperature control elements can be used to control or regulate temperature, and can be controlled or regulated in different ways. Chucks often include multiple temperature sensors to obtain temperature measurements in different regions of the chuck or wafer. Multiple temperature control elements are also typically provided to heat and / or cool the chuck or wafer. Here, the temperature is monitored in multiple regions of the chuck or wafer, and if there is a deviation from a target temperature, the temperature control elements in those regions are controlled accordingly so that the temperature of the wafer or chuck in those regions is always substantially the same and substantially corresponds to the target temperature. Summary of the Invention [Problem to be solved by the invention]

[0003] However, regulation or control as described in the process is expensive to implement, and while areas of the chuck or wafer where functional testing is not performed are continuously temperature controlled, the temperature of these areas has virtually little or no effect on the functional testing.

[0004] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a temperature control or regulation method, temperature control device and wafer testing system for simplified and advantageous temperature control of a chuck or wafer. [Means for solving the problem]

[0005] This object is achieved by the subject matter of the independent claims. Advantageous embodiments are the subject matter of the dependent claims.

[0006] One aspect of the present invention relates to a method for controlling or regulating the temperature of a wafer chuck, the method including the steps of detecting the position of a testing means for testing the wafer, determining respective spatial distances between the testing means and a plurality of temperature measurement means for measuring the temperature of the chuck or a wafer mounted or clamped by the chuck, selecting at least one temperature measurement means of the plurality of temperature measurement means as a reference temperature measurement means, and controlling or regulating the temperature of the chuck based on the temperature of the chuck or wafer measured by the selected reference temperature measurement means.

[0007] In particular, such a method allows for simplified and advantageous temperature control of the chuck or wafer, since the temperature control of the entire chuck is substantially uniform, for example, by controlling all means for temperature control of the chuck. Therefore, the method has low requirements for processing and / or control or regulation electronics. Also, there is no unnecessary heating and / or cooling of areas of the chuck or wafer that are not critical to the functional test being performed.

[0008] Preferably, the chuck has a platform for clamping the wafer, and the wafer is attached or clamped by the chuck, for example, by generating a magnetic field or a vacuum.

[0009] Preferably, the chuck includes a plurality of temperature measuring means arranged in or on the chuck for measuring the temperature of the chuck or wafer, preferably at several different locations.

[0010] The wafer is mounted or clamped by a chuck so that a testing means, such as probe needles or a probe card, can contact different locations on the wafer surface and test structures located in or on the wafer surface, where a plurality of probe needles or probe fingers are preferably aligned to contact contact surfaces of the structures under test and can examine properties of the structures, for example by introducing a current or applying a voltage.

[0011] The temperature of the chuck is preferably controlled or regulated substantially uniformly, i.e., substantially the same or consistently, particularly preferably by uniform control of one or more means for controlling the temperature of the chuck, such as several electrothermal converters arranged within or on the chuck.

[0012] Preferably, the step of selecting a temperature measurement means as the reference temperature measurement means includes the step of selecting the temperature measurement means which is the shortest spatial distance from the test means.

[0013] Preferably, the temperature of the chuck, and in turn the temperature of the wafer, is controlled or regulated based on the temperatures measured by individual temperature measurement means of the plurality of temperature measurement means. Preferably, the temperature measurement means having the smallest spatial distance from the temperature measurement means or testing means, or closest to the current location of the testing means, is used. Thus, advantageously, the temperature measurement means that potentially detects or records temperature changes in the region of the wafer where the structure under test is most accurately and / or first in time is selected as the reference temperature measurement means for controlling or regulating the temperature of the chuck or wafer.

[0014] Preferably, if the determined spatial distances of two or more temperature measurement means are within a certain tolerance T± and / or are substantially the same size, selecting a reference temperature measurement means includes selecting, from among the two or more temperature measurement means, a temperature measurement means having the largest temperature difference Tdiff and / or temperature change per time Tgrad, or selecting two or more temperature measurement means as reference temperature measurement means, wherein control or regulation of the chuck temperature is based on the arithmetic mean or average of the temperatures measured by the reference temperature measurement means. Here, the tolerance T± may correspond, for example, to an equivalent of preferably less than about 10 cm, more preferably less than about 1 cm, and more preferably less than about 0.1 cm. Substantially the same size preferably corresponds, for example, to a distance difference of less than about 10%, more preferably less than about 1%, and more preferably less than about 0.1%. The value may be selected according to structural conditions, particularly the number and / or arrangement of the multiple temperature measurement means, and / or the desired behavior of the temperature control or regulation. Alternatively, two or more temperature measurement means may be selected as reference temperature measurement means, and the temperatures measured by the two or more reference temperature measurement means, for example, preferably an average of the measured temperatures, may be used to regulate or control the temperature of the chuck.

[0015] where the temperature difference, Tdiff, is the amount of difference between the measured temperature, T(t), and the target temperature, Tsoll, of the chuck or wafer: Tdiff=|T(t)-Tsoll|, or The amount of difference between the measured temperature T(t) and a previously measured temperature T(tx) of the same temperature measuring means: Tdiff=|T(t)-T(tx)|, or The amount of difference between the measured temperature T(t) and the average temperature Tavg of multiple temperature measurement means: Tdiff=|T(t)-Tavg|=|T(t)-(T1+T2+T3+...+TX) / X| Corresponds to.

[0016] Preferably, the temperature change per unit time Tgrad is compared within a specific time period t1. Tgrad = |(T(x)-T(x+t1)) / t1|

[0017] In this manner, the temperature measurement means that detects the largest temperature decrease or increase within a period t1 can be preferably selected as the reference temperature measurement means, the period t1 being preferably less than about 5 seconds, more preferably less than about 1 second.

[0018] Particularly preferably, the spatial distance between the test means and the temperature measuring means is determined based on vector coordinates. Here, to determine the respective distances between the test means and the temperature measuring means, the positions of the test means and the temperature measuring means are preferably projected onto a coordinate system and the connecting vector, and further its quantity (length), is calculated. To determine the distance, 2D and / or 3D coordinates of the test means and the temperature measuring means can be used, with the 2D coordinates of the test means and / or the temperature measuring means preferably relating to a plane parallel to the wafer surface. An exemplary preferred determination of the distance based on vector coordinates is explained in more detail in the detailed description of the drawings.

[0019] A further aspect of the present invention relates to a temperature control device for controlling the temperature of a chuck and / or a wafer positioned or clamped by the chuck, comprising: a first communication interface for communicating with the chuck, the first communication interface being suitable for transmitting electrical signals; and a control unit connected to the first communication interface for receiving electrical signals from a plurality of temperature measurement means for measuring the temperature of the chuck or wafer, selecting one of the temperature measurement means as a reference temperature measurement means, and controlling or regulating the temperature of the chuck based on the temperature of the chuck or wafer measured by the selected reference temperature measurement means.

[0020] Preferably, the temperature control device is further adapted to select, as the reference temperature measurement means, the temperature measurement means that is at the smallest spatial distance from the testing means for testing the wafer.

[0021] Further preferably, the control unit of the temperature control device is adapted to select the temperature measuring means having the greatest amount of temperature difference Tdiff and / or temperature change per time Tgrad as the reference temperature measuring means if the determined spatial distances of two or more temperature measuring means are within a certain tolerance T± and / or are substantially the same size.

[0022] Particularly preferably, the temperature control device comprises: a second communication interface for supplying and / or discharging a temperature control medium into and / or out of the chuck to control the temperature of the chuck; and / or a third communication interface for communicating with at least one electrical-thermal converter for controlling the temperature of the chuck; Further provided are:

[0023] A further aspect relates to a wafer testing system for testing a wafer, comprising: a chuck for providing or clamping and temperature controlling a wafer, the chuck comprising a plurality of temperature measuring means for measuring the temperature of the chuck and / or a wafer mounted or clamped by the chuck; at least one testing means for testing the wafer; position detecting means for detecting the position of the testing means relative to the chuck or wafer; and a temperature control device as described in the process.

[0024] Hereinafter, with reference to the drawings, individual embodiments for solving the purpose will be described as examples. Some of the described individual embodiments have features that are not absolutely necessary for carrying out the claimed subject matter, but that provide desired properties in specific applications. Therefore, embodiments that do not include all of the features of the embodiments described below should also be considered to be disclosed as falling under the described technical teachings. Furthermore, to avoid unnecessary repetition, certain features will be mentioned only in connection with the individual embodiments described below. Therefore, it should be noted that the individual embodiments should be viewed as a whole, not just individually. Based on this summary, those skilled in the art will recognize that the individual embodiments can be modified by including individual or multiple features of other embodiments. It is pointed out that a systematic combination of the individual embodiments with one or more features described in connection with other embodiments may be desirable and practical and should therefore be considered and considered to be encompassed by this description. [Brief explanation of the drawings]

[0025] [Figure 1] FIG. 1 illustrates an exemplary embodiment of a wafer testing system having a wafer mounted on a chuck, a testing means for testing the wafer, and a temperature control device that enables temperature control of the chuck by a plurality of electrothermal converters. [Figure 2]FIG. 1 illustrates an alternative exemplary embodiment of a wafer testing system including a chuck, a testing means for testing a wafer, and a temperature control device for controlling the temperature of the chuck by introducing a temperature control medium into the chuck. [Figure 3] 1 shows a plan view of a chuck, a mounted wafer having a plurality of test structures, a testing means for testing the plurality of test structures, and a plurality of temperature measuring means. [Figure 4] FIG. 1 illustrates an exemplary profile of the temperature of a chuck or wafer measured by multiple temperature measurement means. [Figure 5] FIG. 10 illustrates an alternative exemplary embodiment of a chuck with two separate temperature control circuits for different temperature control mediums. DETAILED DESCRIPTION OF THE INVENTION

[0026] FIG. 1 shows a cross-sectional view of an exemplary, particularly preferred embodiment of a wafer testing system 20. The illustrated wafer testing system 20 includes a chuck 1, or holding / clamping device, for mounting or clamping a wafer 2. The wafer 2 is preferably mounted parallel to a substantially flat surface of the chuck 1 by an applied magnetic field. Alternatively, the chuck 1 may have a plurality of suction grooves (not shown), through which the wafer may be sucked by negative pressure, thereby clamping or positioning the wafer by the chuck 1. As a result of the suction, the wafer 2 is pressed against or arranged on the chuck 1, thereby ensuring good heat transfer between the chuck 1 and the wafer 2. The chuck 1 preferably includes a ceramic body, e.g., aluminum oxide or aluminum nitride, and more preferably includes a conductive shielding layer on the surface of the chuck 1 facing the wafer 2. The wafer 2 is preferably in substantial surface contact with the shielding layer of the chuck 1. The wafer 2 further includes a wafer surface 3, preferably including one or more structures 4 under test. The structures under test 4 are, for example, integrated circuits or electrical components (diodes, transistors, etc.), where the wafer 2 may have different numbers and / or arrangements of structures under test 4 depending on the size of the wafer surface 3 and the structures under test 4.

[0027] In this connection, reference is made to particularly preferred embodiments of the chuck as described in patent specifications DE 10 2005 014513 B4 and DE Utility Model 20 2005 014918 U1, the contents of which are incorporated into the present disclosure by reference.

[0028] A preferred embodiment of the illustrated wafer testing system 10 further comprises at least one testing means 22 capable of testing the structures 4 of the wafer 2 to be tested. Particularly preferably, a suitable testing means 22 has one or more probe needles 23, each of which contacts a contact point of the structure 4 under test. Properties of the structure 4 can be inspected or tested in this way, for example, by introducing a current or applying a voltage and / or measuring the voltage / current by the probe needles 23. Control of the testing means 22, and in particular the positioning of the testing means 22 relative to the wafer 2 or the structure 4, is performed, for example, by a (preferably separate) control device. In a preferred embodiment of the illustrated wafer testing system 20, the testing means 22 moves over the wafer 2 according to the position of the structure 4 under test and is positioned on the wafer surface 3. Also preferably, position detection means 28 are provided for detecting and / or verifying the position of the testing means 22. Preferably, such position detection means 28 receives the position of the testing means 22, for example, from an actuation or positioning device for moving the testing means 22. Alternatively and / or additionally, the position detection means 28 may detect the position of the testing means 22 by means of a sensor (e.g., an infrared sensor, a resistive sensor and / or a magnetic sensor). The position of the testing means 22 is detected or determined using the position detection means 28, preferably with respect to a reference element / point on the wafer 2 and / or chuck 1 (e.g., the wafer surface 3, the structure 4 on the wafer, the temperature detection means 6 on the chuck).

[0029] As an alternative to the test means 22 described in the process, a test means 22 suitable for testing a wafer 2 may comprise a so-called probe card 24, which preferably comprises a circuit board 25 having a plurality of contact elements 26 that can make contact with contact points of a plurality of structures under test 4. The use of such a probe card 24 has the particular advantage that a plurality of structures 4 can be tested substantially simultaneously or one after the other instantly, without the need to realign the test means 22. Figure 2 shows a further exemplary and preferred embodiment of a wafer testing system 20 having such a probe card 24 as test means 22 for testing structures 4 on a wafer 2.

[0030] In the illustrated preferred embodiment, the chuck 1 includes a plurality of temperature measuring means 6 (e.g., temperature sensors: PT100, NTC, PTC, etc.) suitable for measuring the temperature of the wafer 2 or the chuck 1 in a range close to or substantially adjacent to the wafer 2. In the illustrated embodiment, a plurality of temperature measuring means 6 (preferably five) are provided adjacent to one another at substantially regular intervals in a plane substantially parallel to the wafer surface 3. Preferably, the temperature measuring means 6 are arranged within the chuck 1 near the surface of the chuck 1 on which the wafer 2 is clamped / mounted, so that the temperature of the wafer 2 can be advantageously transmitted to the chuck 1. The chuck 1 according to the illustrated exemplary embodiment preferably includes one or more electrothermal converters 9 (e.g., electric heating elements and / or Peltier elements) to enable temperature control of the chuck 1 and subsequently the wafer 2. Preferably, the chuck 1 includes five or more, more preferably ten or more, electrothermal converters 9, preferably arranged substantially uniformly distributed within the chuck 1, to advantageously control, in particular, cool and / or heat, the temperature of the chuck 1.

[0031] As an alternative to the exemplary embodiment of chuck 1 described in the process, other means or mechanisms for temperature control or regulation of chuck 1 may be installed. A further preferred embodiment of chuck 1 has a line 8 suitable for the flow of temperature-controlled medium 18, particularly temperature-controlled air and / or temperature-controlled liquid. Preferably, medium line 8 of chuck 1 is designed so that the temperature of preferably a large portion of chuck 1 can be substantially uniformly controlled by temperature-controlled medium 18 flowing through medium line 8. Particularly preferably, medium line 8 has a substantially serpentine-shaped course at least partially inside chuck 1. FIG. 2 shows a further exemplary and preferred embodiment of a wafer testing system 20 having chuck 1, the temperature of which can be controlled or regulated by temperature-controlled medium 18.

[0032] The exemplary and preferred embodiment of the wafer testing system 20 shown in FIG. 1 preferably further comprises a temperature control device 10 for controlling or regulating the temperature control of the chuck 1 or wafer 2. Preferably, the temperature control device 10 comprises means for communicating with the chuck 1, e.g., in the form of one or more communication interfaces 12 by which the temperature control device 12 can be connected to the chuck 1. Particularly preferably, the temperature control device 12 has at least one first communication interface 12a that is particularly suitable for transmitting electrical signals, in particular electrical signals from one or more temperature measurement means 6, to the temperature control device 12. Even more preferably, the temperature control device 12 according to the exemplary and preferred embodiment has at least one further communication interface 12c that particularly enables communication with one or more electro-thermal converters 9 of the chuck 1, in particular control of the electro-thermal converters 9. Alternatively and / or additionally, a single communication interface 12 may be provided for communication with the temperature measurement means 6 and the electro-thermal converters 9.

[0033] The illustrated exemplary temperature control device 12 preferably further comprises a control unit 14 (e.g., a (micro)controller, FPGA, etc.) connected to one or more communication interfaces 12 and capable of communicating with the chuck 1 via these interfaces. In particular, the control unit 14 is suitable for receiving, processing, and / or evaluating signals from the temperature measurement means / temperature sensors 6 of the chuck 1. Furthermore, the exemplary and preferred embodiment of the control unit 14 of FIG. 1 is suitable for influencing or controlling / regulating the temperature of the chuck 1 or the wafer 2. In particular, the control unit 14 is suitable for controlling the electrothermal converter 9 of the chuck 1 in order to increase, decrease, and / or keep the temperature of the chuck 1 substantially constant. Further preferably, the control unit 14 is designed to obtain the position of the testing means 22 from the position detection means 28. Alternatively and / or additionally, the control unit 14 is preferably suitable for controlling or regulating the supply and / or discharge of the temperature control medium 18 for temperature control of the chuck 1 and / or the temperature control medium 18. This will be explained in more detail with reference to FIG. 2.

[0034] Furthermore, a particularly preferred embodiment of the control unit 14 shown in FIG. 1 is a method for controlling or regulating the temperature of the chuck 1 and / or the wafer 2 mounted or clamped by the chuck 1, wherein the temperature control device 10: determining the respective spatial distances between the test means 22 and a plurality of temperature measuring means 6 for measuring the temperature of the chuck 1 or the wafer 2 clamped by the chuck 1; The present invention enables a method to be carried out, including

[0035] The control unit 14 in the illustrated preferred embodiment is able to determine the respective spatial distances between the testing means 22 of the chuck 1 and the plurality of temperature measuring means 6 .

[0036] An exemplary and preferred method suitable for this step includes a step of defining the positions of the testing means 22 and the plurality of temperature measuring means 6 in a (preferably Cartesian) coordinate system. The position of the testing means 22 is preferably approximated as a point or a substantially point-like infinitesimal area, more preferably in a plane substantially parallel to the wafer surface 3. Particularly preferably, this point substantially corresponds to the geometric center of gravity of the testing means 22 or the geometric center of gravity of its projection onto the plane defined by the temperature measuring means 6 of the chuck 1. More preferably, the reference point is determined as the coordinate origin or pole / zero point of a two-dimensional coordinate system, preferably located on the plane of the plurality of temperature measuring means 6. More preferably, the positions of the individual temperature measuring means 6 and testing means 22 are approximated as a substantially point-like, infinitesimal area (preferably corresponding to the geometric center of gravity) and assigned to coordinates in the coordinate system. Furthermore, the control unit 14 preferably determines the distance of each temperature measuring means 6 from the testing means 22 by calculating the length (quantity) of the connecting vector between the respective coordinates of the testing means 22 and the temperature measuring means 6.

[0037] The methods described in the process for determining the spatial distance between the testing means 22 and the respective temperature measuring means 6 represent exemplary and preferred embodiments only. For example, the position of the testing means 22 or the temperature measuring means 6 may be assigned to coordinates in a three-dimensional coordinate system (without projection onto a particular plane, see FIG. 2). Also, any alternative method for determining the distance of the testing means 22 from the temperature measuring means 6 may be used.

[0038] Further, an exemplary and preferred method for temperature control or regulation of the chuck 1 or the wafer 2 clamped by the chuck 1 is: selecting a temperature measurement means 6 as a reference temperature measurement means from among a plurality of temperature measurement means 6; Preferably, the temperature measuring means 6 with the smallest spatial distance from the testing means 22 is selected.

[0039] For this purpose, the control unit 14 preferably compares the determined spatial distances Ai of the individual temperature measuring means 6 from the testing means 22 and selects the temperature measuring means 6 with the smallest distance Ai as the reference temperature measuring means. Particularly preferably, if two or more temperature measuring means 6 have substantially the same distance with a difference of less than a certain tolerance T± (preferably less than about 1 cm, more preferably less than about 0.1 cm), the (further) selection of the relevant temperature measuring means 6 is made by selecting the temperature measuring means 6 with the largest temperature difference Tdiff and / or temperature change per time Tgrad from among the two or more temperature measuring means 6 (whose determined spatial distances from the testing means 22 are within the certain tolerance T± and / or are substantially the same).

[0040] Alternatively, two or more temperature measuring means 6 may be selected as reference temperature measuring means, and for example, the average value of the temperatures measured by the reference temperature measuring means may be used as the reference temperature for controlling the temperature of the chuck 1.

[0041] In the process described, when two or more temperature measuring means 6 are at substantially the same distance from the testing means 22, the temperatures or temperature profiles measured by the temperature measuring means 6 that are related, i.e. have substantially the same distance from the testing means, are further preferably compared.

[0042] Here, the individual temperature differences Tdiff of the temperature measuring means 6 are expressed as follows: The amount of difference between the temperature T(t) measured by the temperature measuring means 6 at time t and the target temperature Tsoll of the chuck or wafer: Tdiff=|T(t)-Tsoll|, or The amount of difference between the temperature T(t) and a temperature T(tx) previously measured by the same temperature measuring means 6: Tdiff = |T(t) - T(tx)| (This temperature-difference-based selection process is shown as an example in Figures 3 and 4.) or The amount of difference between the temperature T(t) and the average temperature Tavg of a plurality (X) of the temperature measuring means 6 (preferably all the temperature measuring means 6 of the chuck 1): Tdiff=|T(t)-Tavg|=|T(t)-(T1+T2+T3+...+TX) / X| Corresponds to.

[0043] The temperature change per hour Tgrad within a particular period t1 preferably corresponds to the amount of change in temperature measured by the temperature measuring means 6 over a certain duration or period t1: Tgrad = |T(x)-T(x+t1)|

[0044] As a result, the temperature measurement means 6 that detects the greatest temperature loss or greatest temperature increase within the time period t1 may then be selected as the reference temperature measurement means. The time period t1 over which the temperature profile is determined is preferably less than about 5 seconds, more preferably less than about 1 second, more preferably less than about 0.1 seconds.

[0045] The parameters described in the process of (further) selecting one temperature measurement means 6 from the associated temperature measurement means 6 can be used for the step of selecting the reference temperature measurement means, both alone and in any combination, possibly with different weightings. The same applies to the determined distances of the associated temperature measurement means. Further alternative parameters may also be used for selecting the reference temperature measurement means.

[0046] Furthermore, an exemplary and preferred method for controlling or regulating the temperature of chuck 1 or wafer 2 clamped by chuck 1 includes controlling or regulating the temperature of chuck 1 based on the temperature of chuck 1 or wafer 2 measured by a selected reference temperature measurement means.

[0047] Preferably, the temperature of the entire chuck 1, i.e., preferably all means for temperature control of the chuck 1 (e.g., electrothermal converter, temperature control medium / medium lines), are controlled to be substantially uniform / identical so that the temperature of the chuck 1 is controlled substantially uniformly. To control or adjust the temperature of the chuck 1, preferably only the measured temperature of a selected reference temperature measurement means is used. Preferably, the temperature measured by the reference temperature measurement means is compared with a specified target temperature of the chuck 1 or the wafer 2 and is substantially adapted to the target temperature of the chuck 1 or the wafer 2, for example, by correspondingly controlling the temperature control means (e.g., electrothermal converter 9) (see also FIG. 4). As a result, different areas of the chuck 1 can be at different temperatures, which affects the temperature of the wafer 2.

[0048] FIG. 2 shows a cross-sectional view of a wafer test system 20 according to a further exemplary and particularly preferred embodiment (similar to the embodiment of FIG. 1). The illustrated wafer test system 20 comprises a chuck 1 that clamps a wafer 2, preferably by application of a magnetic field or negative pressure. Like the chuck 1 of FIG. 1, the chuck 1 preferably has a plurality of temperature measurement means 6 (e.g., PT100, NTC, PTC) for measuring the temperature of the chuck 1 or the wafer 2, connected to a control unit 14 via a first communication interface 12a. Like the system of FIG. 1, the wafer test system 20 is suitable for carrying out the method described in the process for controlling the temperature of the chuck 1 or the wafer 2.

[0049] However, as an alternative to the wafer testing system 20 shown in Figure 1, the system shown in Figure 2 is provided with a so-called probe card 24 as testing means 22 for testing the wafer 2 or structures 4 on the wafer 2. Such a probe card 24 preferably comprises a circuit board 25 having a plurality of contact elements 26 arranged such that the plurality of contact elements 26 of the probe card 24 can make contact with contact points of several structures 4 under test on the wafer 2. Thus, by aligning or positioning the testing means 22 or probe card 24 once, several structures can advantageously be tested substantially simultaneously and / or consecutively, thereby accelerating the testing method.

[0050] Also shown is a different determination of the spatial distance between the temperature measuring means 6 and the testing means 22 or the probe card 24, respectively. Unlike FIG. 1, the position of the probe card 24 is not projected onto a plane formed by the positions of the temperature measuring means 6, but is determined according to an alternative method. This exemplary and preferred method assigns coordinates in a three-dimensional (preferably Cartesian) coordinate system to the testing means 22 (probe card 24) and the temperature measuring means 6, and determines the length or quantity of the connection vector in three-dimensional space. As explained with reference to FIG. 1, the positions of the individual temperature measuring means 6 and testing means 22 are preferably approximated to substantially point-like infinitesimal regions (preferably corresponding to their respective geometric correspondences). The distance Ai corresponds to the length (quantity) of the connection vector between the coordinates of the temperature measuring means 6 and the testing means 22.

[0051] Also, unlike the embodiment shown in FIG. 1 , the temperature control or means for controlling or regulating the temperature of the chuck 1 comprises a temperature control medium 18 and a medium line 8 arranged within the chuck 1 for conducting the temperature control medium 18. For example, the temperature control medium may comprise temperature-controlled air and / or a temperature-controlled liquid, which flows through the chuck's medium line 8 to achieve temperature control (increasing / decreasing / maintaining the temperature of the chuck 1). Preferably, the chuck's medium line 8 is designed to be at least partially substantially serpentine so that advantageous temperature control of the chuck 1 can be achieved by the temperature control medium 18. According to the illustrated preferred embodiment, the temperature control device 10 has a corresponding communication interface 12b suitable, for example, for supplying and / or discharging the temperature control medium into and / or out of the chuck 1. Preferably, a correspondingly configured control unit 14 is suitable for influencing or adapting the flow parameters, temperature, and / or composition of the temperature control medium 18 as needed. Heptane, as well as various alcohols such as amyl alcohol (pentanol) and methanol, are particularly suitable as temperature control media. Silicone-based thermal oils are more suitable. Temperature-control fluids containing perfluorinated polyethers (e.g., available from Solvay Solexis SpA under the trade name Galden HT), poly(oxyperfluoro-n-alkylenes) (e.g., available from Solvay Solexis SpA under the trade name Galden ZT), and / or mixtures of triethoxyalkylsilanes (e.g., available from DWS Synthesetechnik under the trade name DW-Therm) are preferably used. However, other materials known to those skilled in the art can also be used. More preferably, chuck 1 may have several (independent) medium lines 8, preferably suitable for temperature control of the majority of chuck 1, which further preferably allows for substantially uniform control of the temperature of chuck 1 or of all temperature-control elements of the chuck.

[0052] FIG. 3 shows a top view of a chuck 1 according to a preferred embodiment having a mounted or clamped wafer 2 with a substantially circular wafer surface 3. The wafer has a plurality (preferably 1 to about 1000, more preferably about 5 to about 200, more preferably about 10 to about 100, e.g., 14 as shown in FIG. 3) of structures under test 4 arranged in a substantially uniform pattern in or on the wafer 2 (wafer surface 3). In the illustrated exemplary embodiment, the chuck 1 has a plurality (preferably about 3 to about 20, e.g., five as shown in FIG. 3) of temperature measurement means 6a, 6b, 6c, 6d, and 6e, preferably PT-100 temperature sensors, preferably positioned below the wafer 2. Alternatively and / or additionally, other temperature sensors, such as HTC and / or NTC, may be provided to measure the temperature of the chuck 1 or the wafer 2.

[0053] The temperature measuring means 6a-6e are preferably arranged according to a pattern as shown, and more preferably are substantially uniformly distributed across the wafer surface 3. Figure 3 also shows a testing means 22 having a plurality (preferably four) probe needles 23 (not identified), which are suitable for contacting the contact surfaces of the structure under test 4 in order to test the contact surfaces of the structure under test 4.

[0054] 3, the testing means 22 is positioned substantially above one of the structures 4 under test, with its probe needles 23 in contact with the contact surfaces of the structures 4. In this state, the testing means 22 has a position (preferably approximated, substantially point-like, and substantially corresponding to the geometric center of gravity) at approximately the same distance from the positions (preferably approximated, substantially point-like, and substantially corresponding to the geometric center of gravity) of the temperature measuring means 6a, 6b, and 6c (or the distance between the testing means 22 and one of the temperature measuring means A6a, A6b, or A6c has a difference within a specified tolerance T±). In such a case, when using the method described in the temperature control or adjustment process for the chuck 1, it is preferable to select a reference temperature measuring means from among the temperature measuring means 6a, 6b, and 6c, taking into account the temperature difference Tdiff and / or temperature gradient Tgrad of the temperature measuring means 6a, 6b, and 6c.

[0055] FIG. 4 shows an exemplary temperature profile for the configuration shown in FIG. 3 and described in the process. Shown here are profiles of temperatures T6a, T6b, T6c, T6d, and T6e measured by temperature measurement devices 6a-6e. As described in the process, a reference temperature measurement device is selected from among temperature measurement devices 6a, 6b, and 6c on which to base the temperature regulation or control of chuck 1 or wafer 2. To this end, in this preferred example, the temperature difference Tdiff between temperatures T(t) measured by temperature measurement devices 6a-6c at time t is compared with the temperature measured by each of temperature measurement devices 6a-6c at time tx (i.e., a duration x before time t). Tdiff6a = |T6a(t) - T6a(tx)| Tdiff6b = |T6b(t) - T6b(tx)| Tdiff6c=|T6c(t)-T6c(tx)|

[0056] In FIG. 3, the temperature difference Tdiff6a of the temperature measuring means 6a is shown as an example or representative, and this exemplary scenario also corresponds to the maximum temperature difference of the temperature measuring means 6a to 6c.

[0057] The temperature differences Tdiff6a, Tdiff6b, and Tdiff6c are compared to one another to determine the temperature difference with the highest value. In an exemplary method, the temperature measurement means 6 associated with the highest temperature difference is selected as the reference temperature measurement means. Thus, in this exemplary and preferred method, temperature measurement means 6a is selected as the reference temperature measurement means and used to control the temperature of chuck 1 or wafer 2.

[0058] More preferably, the temperature control (control or regulation of temperature) is performed by substantially adjusting the temperature measured by the temperature measurement means 6a. As can be seen in Figure 4, the temperature control affects each of the plurality of temperature measurement means 6, and thus preferably substantially all or at least most of the area of ​​the chuck 1. In this example, the temperature measurement means 6b-6e measure values ​​that are (clearly) below the target temperature of the wafer 1 or chuck 1.

[0059] The method described with reference to Figures 3 and 4 is merely an exemplary and preferred embodiment of a method for temperature control of a chuck or wafer. In particular, the parameters used to select the reference temperature measurement means may be changed according to requirements and / or desires. Here, for example, the temperature gradient of the temperature measurement means may be selected or used as a determining parameter. The measured temperatures of two or more temperature measurement means 6 may also be used as a reference value for temperature control, for example, by averaging the measured temperatures. The temperature control method may also be performed in an alternative manner, for example, by substantially halving the difference between the temperature of the reference temperature measurement means and the target temperature of the chuck 1 or wafer 2.

[0060] FIG. 5 shows a further preferred embodiment of the chuck 1, in which temperature control of the chuck 1 is enabled by preferably different temperature control media 18a, 18b in the first and second temperature control circuits 30, 32. More preferably, the two temperature control circuits 30, 32 each have medium lines 8a, 8b that extend substantially serpentinely in at least certain regions. In this exemplary and preferred embodiment, advantageous temperature control of the chuck 1 is enabled by using different temperature control media 18 for temperature control in different temperature ranges. For example, the first temperature control medium 18a is used for a first temperature range, e.g., from about -75°C to about 100°C, and the second temperature control medium 18b is used for a second temperature range, e.g., from about 50°C to about 400°C. Heptane, as well as various alcohols such as amyl alcohol (pentanol) and methanol, are particularly suitable as the temperature control media 18. Silicone oil-based thermal oils are more preferably used. Preferably, a temperature control fluid containing a perfluorinated polyether (e.g., available from Solvay Solexis SpA under the trade name Galden HT), a poly(oxyperfluoro-n-alkylene) (e.g., available from Solvay Solexis SpA under the trade name Galden ZT), and / or a mixture of triethoxyalkylsilanes (e.g., available from DWS Synthesetechnik under the trade name DW-Therm) is used. However, other materials known to those skilled in the art can also be used.

[0061] 5 preferably includes one or more electrothermal converters 9 to allow for further advantageous temperature control of the chuck 1. The one or more electrothermal converters 9 are preferably particularly suited for temperature control that can be adjusted accurately and quickly over a relatively low temperature range of about +-50°C.

[0062] In this connection, reference is made to a preferred embodiment of a chuck particularly suitable for this purpose, which is described in patent specification DE 10 2005 049 598 B4, the content of which is incorporated into the present disclosure by reference. [Explanation of symbols]

[0063] 1 chuck 2 wafers 3 Wafer surface 4. Structure under test 6 Temperature measuring device 8 Media Line 9 Electrical-thermal converter 10 Temperature control device 12 Communication Interface 14 Control Unit 18 Temperature control medium 20 Wafer Test System 22 Testing Methods 23 Probe needle 24 probe cards 25 Circuit Board 26 Contact Elements 28 Position detection means 30 First temperature control circuit 32 Second temperature control circuit

Claims

1. 1. A method for controlling or regulating the temperature of a chuck (1) for a wafer (2), comprising: placing a testing means (22) for testing the wafer (2) above one of a plurality of structures to be tested (4) on the wafer (2); detecting the position of said testing means (22); determining the respective spatial distances between the testing means (22) and a plurality of temperature measuring means (6) for measuring the temperature of the chuck (1) or a wafer (2) mounted or clamped by the chuck (1); selecting at least one temperature measurement means (6) from the plurality of temperature measurement means (6) as a reference temperature measurement means; and controlling or adjusting the temperature of the chuck (1) based on the temperature(s) of the chuck (1) or the wafer (2) measured by the selected reference temperature measurement means; The step of selecting the temperature measurement means (6) as the reference temperature measurement means comprises: selecting the temperature measuring means (6) that is the shortest spatial distance from the testing means (22); If the determined spatial distances of two or more temperature measuring means (6) are within a tolerance T± of less than about 10 cm and / or have a difference of less than about 10%; selecting, from the two or more temperature measurement means (6), a temperature measurement means (6) having the largest temperature difference Tdiff and temperature change per time Tgrad, or a temperature measurement means (6) having the largest temperature change per time Tgrad; method.

2. The temperature difference Tdiff is the amount of difference between the measured temperature T(t) and the target temperature Tsoll of the chuck (1) or the wafer (2); or the amount of difference between the measured temperature T(t) and a previously measured temperature T(t-x) of the same temperature measuring means; or The difference between the measured temperature T(t) and the average temperature Tavg of the plurality of temperature measurement means (6), The method of claim 1.

3. The temperature change per unit time Tgrad is compared within a specific period t1. The method of claim 1.

4. The spatial distance between the testing means (22) and the temperature measuring means (6) is determined based on vector coordinates.

4. The method according to any one of claims 1 to 3.

5. A wafer testing system (20) for testing a wafer, comprising: A chuck (1) for mounting or clamping a wafer (2) and for temperature control, the chuck (1) comprising a plurality of temperature measuring means (6) for measuring the temperature of the chuck (1) or a wafer (2) mounted or clamped by the chuck (1); at least one testing means (22) for testing said wafer (2); a position detection means (24) for detecting the position of the testing means (22) relative to the chuck (1) or the wafer (2); a temperature control device (10) for controlling the temperature of the chuck (1) and / or a wafer (2) mounted or clamped by the chuck (1); The temperature control device (10) a first communication interface (12a) for communicating with the chuck (1), the first communication interface (12a) being suitable for transmitting electrical signals; a first communication interface (12a) for receiving electrical signals from a plurality of temperature measurement means (6) for measuring the temperature of the chuck (1) or the wafer (2); Selecting at least one of the temperature measurement means (6) as a reference temperature measurement means; a control unit (14) for controlling or adjusting the temperature of the chuck (1) based on the temperature of the chuck (1) or the wafer (2) measured by the selected reference temperature measuring means; the control unit (14) is adapted to select the temperature measuring means (6) that is the shortest spatial distance from a testing means (22) that tests the wafer (2) as a reference temperature measuring means; The control unit (14) determines whether the spatial distance between two or more of the temperature measuring means (6) is within a tolerance T± of less than about 10 cm and / or the difference is less than about 10%. The temperature measuring means (6) having the largest temperature difference Tdiff and temperature change per time Tgrad, or the temperature measuring means (6) having the largest temperature change per time Tgrad, is suitable for selecting as a reference temperature measuring means. A wafer test system (20).

6. a second communication interface (12b) for supplying a temperature control medium (18) for controlling the temperature of the chuck (1) into the chuck (1) and / or discharging the same out of the chuck (1); and / or and a third communication interface (12c) for communicating with at least one electrothermal converter (9) for controlling the temperature of the chuck (1). The wafer testing system (20) of claim 5.

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