WO2010071276A1

WO2010071276A1 - Stage unit for a probe station and apparatus for testing a wafer including the same

Info

Publication number: WO2010071276A1
Application number: PCT/KR2009/002621
Authority: WO
Inventors: Meang-Kwon Kim; Eung-Su Kim; Su-Hyun Choi; In-Wook Hwang
Original assignee: Secron Co., Ltd.
Priority date: 2008-12-19
Filing date: 2009-05-18
Publication date: 2010-06-24
Also published as: KR20100071241A; KR101015600B1; TWI438863B; TW201025497A

Abstract

In a stage unit for a probe station, a chuck on which a wafer is positioned is provided and includes a flowing path. A pipe line for supplying cooling agent into the chuck is installed to the stage unit, to thereby cool the chuck down to a first temperature. The pipe line is connected to the flowing path and includes a supply line for supplying the cooling agent to the chuck and a discharging line for discharging the cooling agent from the chuck. A heating element is arranged inside the chuck and heats the chuck. A heating block is positioned adjacent to the chuck and evaporates residual cooling agent remaining in the supply line by heat when the chuck is changed from the first temperature to a second temperature higher than the first temperature by the heating element. Accordingly, the chuck may be maintained at a uniform temperature.

Description

STAGE UNIT FOR A PROBE STATION AND APPARATUS FOR TESTING A WAFER INCLUDING THE SAME

Example embodiments relate to a stage unit for supporting a wafer and an inspection apparatus including the same, and more particularly, to a stage unit of which the temperature is varied according to a temperature range of the wafer in an inspection process and an inspection apparatus including the same.

In general, integrated circuit devices are manufactured on a semiconductor substrate such as a wafer, and thus a plurality of chips is fabricated on the wafer in a manufacturing process for a semiconductor device. An electrical inspection process is performed on the whole wafer including the chips using a die sorting process. Each of the chips is cut off from the wafer and assembled with a lead frame, to thereby manufacture a semiconductor device such as a memory device.

An inspection system including a probe apparatus and a tester is usually used for the inspection process performed on the chips on the wafer. Electric power and various test signals are applied to a contact pad of the wafer from a contact terminal of the probe apparatus by the tester and output signals generated from an electrode of the chip are detected and analyzed by the tester. When a specific output signal is out of an allowable range, the tester determines the chip, from which the specific output signal is generated, to be a defective chip.

The probe apparatus usually performs the inspection process under various inspection conditions in view of various usage requirements of each of the chips. For example, the chips on the wafer may be inspected in wide temperature ranges of about 40°C to about 150°C or of about -60°C to about -200°C. For controlling the above wide temperature range, the stage unit is usually heated or cooled by a heater or a cooler in the probe apparatus.

For example, a high-temperature inspection process can be performed immediately after a low-temperature inspection process is completed. While performing the low-temperature inspection process, the cooler provides a cooling agent to the stage unit for reducing the temperature of a wafer chuck. Thereafter, heat is supplied to the stage unit by the heater for performing the high-temperature inspection process. However, the liquefied cooling agent for the low-temperature inspection process is evaporated in the stage unit due to the heat supplied to the stage unit, and thus the vaporized cooling agent is discharged out of the stage unit. In addition, a residual portion of the cooling agent may remain in a supply pipe line and the residual portion of the cooling agent may be unexpectedly supplied into the stage unit, and thus the heated stage unit may have a non-uniform temperature distribution.

Accordingly, example embodiments provide a stage unit of which the wafer chuck has a uniform temperature irrespective of a high-temperature inspection process and a low-temperature inspection process in an inspection system.

Example embodiments provide an inspection system having the above stage unit.

According to some example embodiments of the present inventive concept, there is provided a stage unit for a probe station. A wafer chuck on which a wafer is positioned is provided to the stage unit and includes a flowing path therein. A pipe line through which a cooling agent flows into the wafer chuck is installed to the stage unit, to thereby cool down the wafer chuck to a first temperature. The pipe line is connected to the flowing path and includes a supply line for supplying the cooling agent to the wafer chuck and a discharging line for discharging the cooling agent from the wafer chuck. A heating element is arranged inside the wafer chuck and heating the wafer chuck. A heating block is positioned adjacent to the wafer chuck and evaporates residual cooling agent remaining in the supply line by heat when the wafer chuck is changed from the first temperature to a second temperature higher than the first temperature by the heating element. In an example embodiment, the heating block includes a heating coil surrounding the supply line adjacent to the wafer chuck and heating the supply line and a shielding plate enclosing the heating coil and the supply line to thereby prevent heat generated from the heating coil from being transferred outwards. The stage unit further includes a controller for controlling the heating coil of the heating block such that the heating block is heated to a third temperature for a first time and is reduced to a fourth temperature lower than the third temperature at a second time after an elapse of the first time while the wafer chuck is heated to the second temperature, to thereby minimize thermal damage caused by heat generated from the heating block at the third temperature.

According to some example embodiments of the present inventive concept, there is provided an apparatus for inspecting a wafer. The apparatus includes a chamber having an inspection space in which the wafer is inspected, a stage unit on which the wafer is positioned and a probe card unit at which a probe card for inspecting the wafer is installed. The stage unit includes a wafer chuck having a flowing path therein and supporting the wafer, a pipe line through which cooling agent flows into the wafer chuck to thereby cool down the wafer chuck to a first temperature, the pipe line being connected to the flowing path and including a supply line for supplying the cooling agent to the wafer chuck and a discharging line for discharging the cooling agent from the wafer chuck, a heating element arranged inside the wafer chuck and heating the wafer chuck, and a heating block positioned adjacent to the wafer chuck, the heating block evaporating residual cooling agent remaining in the supply line by heat when the wafer chuck is changed from the first temperature to a second temperature higher than the first temperature by the heating element. In an example embodiment, the heating block includes a heating coil surrounding the supply line adjacent to the wafer chuck and heating the supply line and a shielding plate enclosing the heating coil and the supply line to thereby prevent heat generated from the heating coil from being transferred outwards. The stage unit further includes a controller for controlling the heating coil of the heating block such that the heating block is heated to a third temperature for a first time and is reduced to a fourth temperature lower than the third temperature at a second time after an elapse of the first time while the wafer chuck is heated to the second temperature, to thereby minimize thermal damage caused by heat generated from the heating block at the third temperature.

According to some example embodiments of the present inventive concept, when an inspection mode is changed from a low-temperature process to a high-temperature process, a residual cooling agent in a supply line is evaporated in the supply line. Accordingly, the internal pressure of the supply line increases and a liquefied cooling agent may be sufficiently prevented from flowing into a wafer chuck, to thereby minimize the temperature variation of the wafer chuck and improve the temperature uniformity of the wafer chuck.

Example embodiments will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings. FIGS. 1 to 6represent non-limiting, example embodiments as described herein.

FIG. 1 is a cross-sectional view illustrating a stage unit for a probe station in accordance with an example embodiment of the present invention;

FIG. 2 is a graph showing a relation of temperature and heating time at a heating block of the stage unit shown in FIG. 1; and

FIG. 3 is a cross-sectional view illustrating an apparatus for inspecting a wafer including thestage unit shown in FIG. 1.

Various example embodiments will be described more fully hereinafter with reference to the accompanying drawings, in which some example embodiments are shown. The present invention may, however, be embodied in many different forms and should not be construed as limited to the example embodiments set forth herein. Rather, these example embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the present invention to those skilled in the art. In the drawings, the sizes and relative sizes of layers and regions may be exaggerated for clarity.

It will be understood that when an element or layer is referred to as being "on," "connected to" or "coupled to"another element or layer, it can be directly on, connected or coupled to the other element or layer or intervening elements or layers may be present. In contrast, when an element is referred to as being "directly on," "directly connected to" or "directly coupled to"another element or layer, there are no intervening elements or layers present. Like numerals refer to like elements throughout. As used herein, the term "and/or"includes any and all combinations of one or more of the associated listed items.

It will be understood that, although the terms first, second, third, etc may be used herein to describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer or section from another region, layer or section. Thus, a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section without departing from the teachings of the present invention.

Spatially relative terms, such as "beneath," "below," "lower," "above," "upper" and the like, may be used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as "below"or "beneath" other elements or features would then be oriented "above" the other elements or features. Thus, the exemplary term "below"can encompass both an orientation of above and below. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.

The terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting of the present invention. As used herein, the singular forms "a," "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and/or "comprising," when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.

Example embodiments are described herein with reference to cross-sectional illustrations that are schematic illustrations of idealized example embodiments (and intermediate structures). As such, variations from the shapes of the illustrations as a result, for example, of manufacturing techniques and/or tolerances, are to be expected. Thus, example embodiments should not be construed as limited to the particular shapes of regions illustrated herein but are to include deviations in shapes that result, for example, from manufacturing. For example, an implanted region illustrated as a rectangle will, typically, have rounded or curved features and/or a gradient of implant concentration at its edges rather than a binary change from implanted to non-implanted region. Likewise, a buried region formed by implantation may result in some implantation in the region between the buried region and the surface through which the implantation takes place. Thus, the regions illustrated in the figures are schematic in nature and their shapes are not intended to illustrate the actual shape of a region of a device and are not intended to limit the scope of the present invention.

Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

Hereinafter, example embodiments will be explained in detail with reference to the accompanying drawings.

FIG. 1 is a cross-sectional view illustrating a stage unit for a probe station in accordance with an example embodiment of the present invention. FIG. 2 is a graph showing a relation of temperature and heating time at a heating block of the stage unit shown in FIG. 1.

Referring to FIG. 1, a stage unit 100 for a probe station in accordance with an example embodiment of the present invention may include a wafer chuck 110 for supporting a wafer W, a supply line 121 for supplying a cooling agent into the wafer chuck 110, a discharge line 123 for discharging the cooling agent from the wafer chuck 110 and a heating block 130 evaporating residuals of the cooling agent remaining on the supply line 121.

In an example embodiment, the wafer chuck 110 may be shaped into the wafer W and the wafer W may be stably positioned on the wafer chuck 110. For example, when the wafer W is shaped into a disc shape, the wafer chuck 110 is also shaped into the disc shape. A plurality of chips may be fabricated on the wafer W.

The wafer chuck 110 may move in three dimensions along three respective directions of an x-direction, a y-direction and a z-direction and may be rotated with respect to a central axis thereof. Therefore, the wafer chuck 110 may be coupled to a first driving unit (not shown) for linearly moving the wafer chuck in the x, y and z directions and a second driving unit (not shown) for rotating the wafer chuck 110. The first driving unit may include a pneumatic cylinder, a hydraulic cylinder and a liner motor, and the second driving unit may include a power generator using a screw and a bearing. A plurality of chips of the wafer W on the wafer chuck 110 may be electrically connected to a plurality of tips (not shown) of a probe card (not shown).

A flow path 115 may be provided inside the wafer chuck 110 and a cooling agent may flow along the flow path 115. For example, the flow path 115 may be formed into a zigzag shape. The length and shape of the flow path 115 may be varied in accordance with a temperature range of the stage unit and the cooling agent.

The supply line 121 may be connected to the flow path 115 in the wafer chuck 110, and thus the cooling agent for cooling the wafer chuck 110 may be supplied into the wafer chuck 110 through the flow path 115. When a condensed and liquefied cooling agent is supplied into the inside of the wafer chuck 110 through the supply line 121, the wafer chuck 110 may be sufficiently cooled to a lower temperature, and thus the wafer W may be inspected on the wafer chuck 110 at a first temperature that is lower than a second temperature. The supply line 121 may be connected to a reservoir 120 holding the cooling agent.

In an example embodiment, the discharge line 123 may be connected to the flow path 115 in the wafer chuck 110. The cooling agent for cooling the wafer chuck 110 may be discharged from the wafer chuck 110 through the discharge line 123, and thus the cooling agent may be circulated in the wafer chuck 110 by the supply line 121 and the discharge line 123. Therefore, the cooling agent, supplied through the supply line 121, may be circulated inside the wafer chuck 110, and then discharged from the wafer chuck 110 through the discharge line 123.

The heating block 130 may be positioned adjacent to the wafer chuck 110 and may surround at least a portion of the supply line 121.

The wafer W may be inspected at a second temperature that is higher than the first temperature. That is, when a high-temperature inspection process is performed after a low-temperature inspection process, the wafer W may be inspected at the second temperature higher than the first temperature. In the present example embodiment, a plurality of heating element 150 may be installed in the wafer chuck 110 and thus the wafer chuck 110 may be heated to the second temperature. A first residual cooling agent remaining in the flow path 115 may be evaporated out of the wafer chuck 110. However, the cooling agent may remain in the supply line 121 adjacent to the wafer chuck 110 in spite of the heating element 150 in the wafer chuck 110. The heating block 150 surrounding the supply line 121 may heat a second residual cooling agent remaining in the supply line 121 to thereby evaporate the second residual cooling agent. Accordingly, an internal pressure of the supply line 121 may increase due to the evaporation of the cooling agent and thus the vaporized cooling agent may be permeated into the wafer chuck 110. Therefore, the temperature variation of the wafer chuck 110 may be much more minimized when the vaporized cooling agent is supplied into the wafer chuck 110, rather than when the liquefied cooling agent is supplied into the wafer chuck 110.

In an example embodiment, the heating block 130 may include a heating coil 131 and a shielding plate 133. The heating coil 131 may be positioned neighboring the wafer chuck 110 and surround the supply line 121. Heat is generated from the heating coil 131 and the second residual cooling agent may be evaporated in the supply line 121. For example, the heating coil 131 may include a tungsten (W) coil.

The shielding plate 133 may enclose the heating coil 131 and prevent heat transfer from the heating coil 131 to other elements of the stage unit 100. Accordingly, the heat generated from the heating coil 131 may be intensively transferred into the supply line 133.

Referring to FIGS. 1 and 2, when the heating block 130 is excessively heated, thermal damage may be caused to other elements of the stage unit 100. For that reason, a third temperature T1 may be maintained for a first time t1 and then a fourth temperature T2 lower than the third temperature T1 may be maintained for a second time t2. Accordingly, when the liquefied cooling agent is supplied into the wafer chuck 110 through the supply line 121, the cooling agent may be vaporized at the fourth temperature T2. That is, the cooling agent in the supply line 121 adjacent to the wafer chuck 110 may be vaporized at a relatively lower temperature, and thus the temperature of the wafer chuck 110 may be scarcely varied by the vaporized cooling agent although the vaporized cooling agent may be permeated into the wafer chuck 110. As a result, the temperature of the wafer chuck 110 may be uniformly maintained to be the second temperature.

For example, when the cooling agent has a boiling point of about 76°C, the third temperature may be ranged from about 500°C to about 700°C and the third temperature may be ranged from about 100°C to about 200°C.

In an example embodiment, the stage unit 100 may further include a controller 400 for controlling a temperature of the heating block 130. That is, the heating block 130 may be heated or cooled by the controller 140. For example, the heating block 130 may be maintained at the third temperature T1 for the first time t1 and then to be the fourth temperature T2 at the second time t2.

As described above, the stage unit 100 for the probe station may further include the heating element 150 in the wafer chuck 110.

In an example embodiment, the heating element 150 may be located inside the wafer chuck 110. The wafer chuck 110 may be heated from the first temperature to the second temperature by the heating element 150. For example, the heating element 150 may be arranged as a zigzag shape and may include a heat generator such as a tungsten coil.

FIG. 3 is a cross-sectional view illustrating an apparatus for inspecting a wafer including the stage unit shown in FIG. 1.

Referring to FIG. 3, the apparatus 20 for inspecting a wafer W in an example embodiment of the present invention (hereinafter referred to as inspection apparatus) may include a chamber 205, the stage unit 100 and a probe card unit 250.

The chamber 205 may have an inspection space 220 in which thewafer W may be inspected by the inspection process. The chamber 205 may also include a load section 240 and an inspection section 220 that are arranged in a line with each other. A separation wall 254 may be interposed between the load section 240 and the inspection section 220 and the wafer W may move between the load section 240 and the inspection section through the separation wall 254.

The load section 240 may load and align the wafer W onto the wafer chuck 110 and may unload the wafer W from the wafer chuck 110. An upper opening 222 may be provided at an upper portion of the chamber205 and a probe card 300, which will be described hereinafter, may be installed into the upper opening 222. The load section 240 may include a supporting plate 242 for supporting a wafer cassette holding the wafers W, an aligner (not shown) for aligning the wafers W and a transfer robot (not shown) for transferring the aligned wafers W onto the stage unit 100.

The stage unit 100 may be positioned in the inspection section 220 and the wafer W that is to be inspected in the inspection apparatus 200 may be located on the stage unit 100. A plurality of the chips on the wafer W may make electrical contact with the probe card 300 as the stage unit 100 may move in three-dimensional directions.

The stage unit 100 may be moved linearly in the x, y and z directions and may be rotated with respect to a central axis thereof by a driver 170. In addition, the stage unit 100 may control the temperature of the wafer chuck 110 on which the wafer W is positioned. That is, the stage unit 100 may reduce the temperature of the wafer chuck 110 and thus the wafer W on the wafer chuck 100 may be inspected at a relatively lower temperature in a low-temperature inspection process. In contrast, the stage unit 100 may increase the temperature of the wafer chuck 110 and thus the wafer W on the wafer chuck 100 may be inspected at a relatively higher temperature in a high-temperature inspection process.

The stage unit 100 in the inspection apparatus 200 may have substantially the same structure as the stage unit described with reference to FIGS. 1 and 2, and thus any further detailed descriptions on the stage unit 100 will be omitted.

The probe card unit 250 may be positioned at the upper portion of the stage unit 100, and the probe card 300 may be hold in the probe card unit 250. The probe card 300 may include a disc-shaped printed circuit board (PCB) and a probe tip at a bottom surface thereof. The probe tip may be protruded from the bottom surface of the probe card 300 and may face the wafer chuck 110. A plurality of the chips on the wafer W may make electrical contact with the tester by the probe card 300.

According to the above example embodiment of the present invention, when an inspection mode is changed from a low-temperature process to a high-temperature process, a residual cooling agent in a supply line is evaporated in the supply line. Accordingly, the internal pressure of the supply line increases and a liquefied cooling agent may be sufficiently prevented from flowing into a wafer chuck, to thereby minimize the temperature variation of the wafer chuck and improve the temperature uniformity of the wafer chuck.

The foregoing is illustrative of example embodiments and is not to be construed as limiting thereof. Although a few example embodiments have been described, those skilled in the art will readily appreciate that many modifications are possible in the example embodiments without materially departing from the novel teachings and advantages of the present invention. Accordingly, all such modifications are intended to be included within the scope of the present invention as defined in the claims. In the claims, means-plus-function clauses are intended to cover the structures described herein as performing the recited function and not only structural equivalents but also equivalent structures. Therefore, it is to be understood that the foregoing is illustrative of various example embodiments and is not to be construed as limited to the specific example embodiments disclosed, and that modifications to the disclosed example embodiments, as well as other example embodiments, are intended to be included within the scope of the appended claims.

Claims

A stage unit for a probe station, comprising:

a wafer chuck on which a wafer is positioned, the wafer chuck including a flowing path therein;

a pipe line through which cooling agent flows into the wafer chuck to thereby cool down the wafer chuck to a first temperature, the pipe line being connected to the flowing path and including a supply line for supplying the cooling agent to the wafer chuck and a discharging line for discharging the cooling agent from the wafer chuck;

a heating element arranged inside the wafer chuck and heating the wafer chuck; and

a heating block positioned adjacent to the wafer chuck, the heating block evaporating residual cooling agent remaining in the supply line by heat when the wafer chuck is changed from the first temperature to a second temperature higher than the first temperature by the heating element.
The stage unit of claim 1, wherein the heating block includes:

a heating coil surrounding the supply line adjacent to the wafer chuck and heating the supply line; and

a shielding plate enclosing the heating coil and the supply line to thereby prevent heat generated from the heating coil from being transferred outwards.
The stage unit of claim 2, further comprising a controller for controlling the heating coil of the heating block such that the heating block is heated to a third temperature for a first time and is reduced to a fourth temperature lower than the third temperature at a second time after an elapse of the first time while the wafer chuck is heated to the second temperature, to thereby minimize thermal damage caused by heat generated from the heating block at the third temperature.
An apparatus for inspecting a wafer, comprising:

a chamber having an inspection space in which the wafer is inspected;

a stage unit including a wafer chuck having a flowing path therein and supporting the wafer, a pipe line through which cooling agent flows into the wafer chuck to thereby cool down the wafer chuck to a first temperature, the pipe line being connected to the flowing path and including a supply line for supplying the cooling agent to the wafer chuck and a discharging line for discharging the cooling agent from the wafer chuck, a heating element arranged inside the wafer chuck and heating the wafer chuck, and a heating block positioned adjacent to the wafer chuck, the heating block evaporating residual cooling agent remaining in the supply line by heat when the wafer chuck is changed from the first temperature to a second temperature higher than the first temperature by the heating element; and

a probe card unit at which a probe card for inspecting the wafer is installed.
The apparatus of claim 4, wherein the heating block includes:

a heating coil surrounding the supply line adjacent to the wafer chuck and heating the supply line; and

a shielding plate enclosing the heating coil and the supply line to thereby prevent heat generated from the heating coil from being transferred outwards.
The apparatus of claim 5, wherein the stage unit further includes a controller for controlling the heating coil of the heating block such that the heating block is heated to a third temperature for a first time and is reduced to a fourth temperature lower than the third temperature at a second time after an elapse of the first time while the wafer chuck is heated to the second temperature, to thereby minimize thermal damage caused by heat generated from the heating block at the third temperature.