Patent Description:
The present disclosure relates to a stage.

Patent Document <NUM> discloses a placement apparatus including a top plate made of ceramic, a temperature adjustment body having a cooling jacket and a surface heater integrated with the top plate, a heat-insulating plate integrated with the temperature adjustment body via a heat-insulating ring, and a heat-retaining plate ring mounted on outer peripheral surfaces of the above-mentioned components. Both surfaces of the heat-retaining plate ring are formed in a mirror surface shape so that the radiant heat from the top plate, the surface heater, etc. can be easily reflected and the heat radiation amount from the outer surface of the heat-retaining plate ring can be suppressed. Patent Document <NUM> discloses a prober for inspecting an imaging device by bringing a probe into electrical contact with a wiring layer of the imaging device, while making light incident on the reverse-side irradiation type imaging device formed on a wafer. A light irradiation mechanism includes a plurality of LEDs. Patent Document <NUM> discloses a wafer holding member including a chuck top and a support member therefor having a bottom portion and a cavity portion, wherein the cavity portion contains a cooling mechanism. Patent Document <NUM> discloses a wafer holder including a supporting plate and a temperature control unit therefor, the temperature control unit having through holes for supporting columns. Patent Document <NUM> discloses a mounting apparatus including a temperature control unit integrated with a surface plate. The surface plate is formed of ceramic, and the surface plate and the temperature control unit are coupled to each other.

According to an embodiment of the present disclosure, there is provided a stage comprising the combination of features of independent claim <NUM>.

The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments of the present disclosure, and together with the general description given above and the detailed description of the embodiments given below, serve to explain the principles of the present disclosure.

Reference will now be made in detail to various embodiments, examples of which are illustrated in the accompanying drawings. In the following detailed description, numerous specific details are set forth in order to provide a thorough understanding of the present disclosure. However, it will be apparent to one of ordinary skill in the art that the present disclosure may be practiced without these specific details. In other instances, well-known methods, procedures, systems, and components have not been described in detail so as not to unnecessarily obscure aspects of the various embodiments. In the specification and drawings, constituent elements that are substantially the same will be denoted by the same reference numerals, and redundant descriptions may be omitted. The following description will be made using a vertical direction or relationship in the drawings, but it does not represent a universal vertical direction or relationship.

With reference to <FIG>, an inspection apparatus <NUM> will be described. <FIG> is a view illustrating an exemplary configuration of the inspection apparatus <NUM>. <FIG> is a plan view of the inspection apparatus <NUM> of <FIG>. <FIG> is a view illustrating an exemplary configuration of a wafer transport mechanism of the inspection apparatus <NUM> of <FIG>.

The inspection apparatus <NUM> includes a loader part <NUM>, an inspection part <NUM>, and an apparatus controller <NUM>. The inspection apparatus <NUM> transports a semiconductor wafer (hereinafter, referred to as "wafer W"), which is an inspection object, from the loader part <NUM> to the inspection part <NUM> under the control of the apparatus controller <NUM>, and applies an electrical signal to an electronic device formed on the wafer W so as to inspect various electrical properties. In such an inspection, the electronic device formed on the wafer W is a device under test (DUT).

The loader part <NUM> includes a load port <NUM>, an aligner <NUM>, and a wafer transport mechanism <NUM>.

A cassette C containing a wafer W is placed in the load port <NUM>. The cassette C is, for example, a front opening unified pod (FOUP).

The aligner <NUM> aligns the wafer W with reference to a cutout such as an orientation flat or a notch formed on the wafer W.

The wafer transport mechanism <NUM> transports the wafer W among the cassette C placed in the load port <NUM>, the aligner <NUM>, and a stage <NUM> installed in the inspection part <NUM> described later. The wafer transport mechanism <NUM> has an arm unit <NUM>, a rotational driving mechanism <NUM>, and a vertical driving mechanism <NUM>.

The arm unit <NUM> includes arms 131a and 131b that are installed in two stages in the vertical direction and are independently movable in the horizontal direction. Each of the arms 131a and 131b holds the wafer W.

The rotational driving mechanism <NUM> is installed below the arm unit <NUM>, and rotates the arm unit <NUM>. The rotational driving mechanism <NUM> includes, for example, a stepping motor.

The vertical driving mechanism <NUM> is installed below the rotational driving mechanism <NUM>, and vertically moves the arm unit <NUM> and the rotational driving mechanism <NUM>. The vertical driving mechanism <NUM> includes, for example, a stepping motor. The wafer transport mechanism <NUM> is not limited to the configuration illustrated in <FIG>, and may have, for example, an articulated arm and a vertical driving mechanism.

In the loader part <NUM>, first, the wafer transport mechanism <NUM> transports the wafer W accommodated in the cassette C to the aligner <NUM>. Then, the aligner <NUM> aligns the wafer W. Then, the wafer transport mechanism <NUM> transports the aligned wafer W from the aligner <NUM> to the stage <NUM> installed in the inspection part <NUM>.

The inspection part <NUM> is arranged adjacent to the loader part <NUM>. The inspection part <NUM> includes the stage <NUM>, a lifting mechanism <NUM>, an XY stage <NUM>, a probe card <NUM>, an alignment mechanism <NUM>, a pump <NUM>, a temperature sensor <NUM>, and a temperature controller <NUM>.

A wafer W is placed on the top surface of the stage <NUM>. The stage <NUM> includes, for example, a vacuum chuck or an electrostatic chuck. The stage <NUM> has a coolant flow path, and a coolant such as water or Galden (registered trademark) is supplied from the pump <NUM> to the coolant flow path. As a result, the stage <NUM> is cooled.

The lifting mechanism <NUM> is provided below the stage <NUM>, and moves the stage <NUM> up and down with respect to the XY stage <NUM>. The lifting mechanism <NUM> includes, for example, a stepping motor.

The XY stage <NUM> is installed below the lifting mechanism <NUM>, and moves the stage <NUM> and the lifting mechanism <NUM> in two axial directions (the X direction and Y direction in the drawing). The XY stage <NUM> is fixed to the bottom of the inspection part <NUM>. The XY stage <NUM> includes, for example, a stepping motor.

The probe card <NUM> is arranged above the stage <NUM>. A plurality of probes 24a is disposed on the stage <NUM> side of the probe card <NUM>. The probe card <NUM> is detachably attached to the head plate 24b. A tester (not illustrated) is connected to the probe card <NUM> via a test head T.

The alignment mechanism <NUM> includes a camera 25a, a guide rail 25b, an alignment bridge 25c, and a light source 25d. The camera 25a is attached to the center of the alignment bridge 25c to face downward, and captures an image of, for example, the stage <NUM> and the wafer W. The camera 25a is, for example, a CCD camera or a CMOS camera. The guide rail 25b supports the alignment bridge 25c so as to be movable in the horizontal direction (the Y direction in the drawing). The alignment bridge 25c is supported by a pair of left and right guide rails 25b, and moves in the horizontal direction (the Y direction in the drawing) along the guide rails 25b. As a result, the camera 25a moves between a standby position and a position directly below the center of the probe card <NUM> (hereinafter, referred to as a "probe center") via the alignment bridge 25c. During alignment, the camera 25a located at the probe center captures an image of electrode pads of the wafer W on the stage <NUM> from above while the stage <NUM> is moving in the XY directions, and performs image processing so as to display a captured image on the display device <NUM>. The light source 25d is installed below the alignment bridge 25c and emits light to the stage <NUM>. The light source 25d is, for example, an LED light source in which a large number of light-emitting diodes (LEDs) are arranged, and emits light when an image of the wafer W is captured by the camera 25a. The light source 25d is used as illumination during image capturing.

The alignment mechanism <NUM> moves the camera 25a to the standby position when the alignment of the wafer W in the XY directions is completed. When the camera 25a is located at the standby position, the camera 25a is not present directly below the probe card <NUM>, and is offset in the Y direction. In this state, when the lifting mechanism <NUM> raises the stage <NUM> with respect to the XY stage <NUM>, the plurality of probes 24a comes into contact with the electrode pads of the wafer W on the stage <NUM>, thereby being brought into the state in which an inspection of electrical characteristics of electronic devices on the wafer W can be performed. The probe 24a is an example of contact terminals.

The pump <NUM> is, for example, a mechanical pump that pumps the coolant. The coolant output from the pump <NUM> is circulated between the pump <NUM> and the coolant flow path in the stage <NUM>. The coolant is, for example, water or Galden (registered trademark), which is a colorless and light-transmissive liquid.

The temperature sensor <NUM> detects the temperature of the stage <NUM>. The temperature sensor <NUM> is, for example, a thermocouple embedded in the stage <NUM>.

The temperature controller <NUM> is provided below the stage <NUM>. The temperature controller <NUM> is, for example, a computer. The temperature controller <NUM> executes a temperature control method including a step of detecting the temperature of the stage <NUM> by the temperature sensor <NUM>, and a step of performing lighting control of an LED module of the stage <NUM> and driving control of the pump <NUM> based on the temperature of the stage <NUM> detected by the temperature sensor <NUM>.

When inspecting the electrical characteristics of electronic devices on the wafer W, the wafer W is pressed upward by the lifting mechanism <NUM> in order to ensure electrical contact between the probes 24a and the electrode pads of the wafer W. That is, the probes 24a are pressed against the electrode pads on the wafer W by applying a load. In this case, a load of about <NUM> to about <NUM> may be applied to each probe 24a.

For example, if a load of about <NUM> to about <NUM> is applied to each probe 24a when inspecting one electronic device of a <NUM> square (<NUM> long×<NUM> wide in a plan view) included in the wafer W, a load of about <NUM> to several hundreds of kg or more may be applied to the wafer W when the numbers of the probes 24a and electrode pads are large.

For this reason, the stage <NUM> is required to have high rigidity capable of withstanding the above-described load and to have a high load-resistant strength, and thus to have little displacement caused by deformation.

During the inspection of the electrical characteristics, the heat generation amount of one electronic device (DUT) may become, for example, about <NUM> W to several hundreds of W or more. Therefore, the stage <NUM> is required to have a cooling (heat-absorbing) structure and a heating structure for adjusting the temperature of the electronic devices within a predetermined temperature range (e.g., within ±<NUM> degrees C) with respect to a set temperature in the inspection. In order to keep an electronic device having a large quantity of heat within a predetermined temperature range with respect to the set temperature, it is necessary to perform heat absorption and heating at high speed. Thus, the stage <NUM> is required to have a small heat capacity and a high thermal conductivity. In recent years, since the quantity of heat in electronic devices has tended to increase, there is an increasing demand for, especially, an increase in an endothermic amount.

Details of the stage <NUM> of the embodiment, which meets the requirements described above will be described below.

<FIG> is a cross-sectional view illustrating an exemplary configuration of a stage <NUM> of an unclaimed example. The stage <NUM> includes a base plate <NUM>, a control board <NUM>, a middle plate <NUM>, an LED module <NUM>, a glass plate <NUM>, a top plate <NUM>, a pipe <NUM>, a connecting portion <NUM>, a pipe <NUM>, and an O-ring <NUM>.

Hereinbelow, a description will be made with reference to a vertical direction in the drawing. Further, the term "in a plan view" means "viewed from above to below in a plane".

The base plate <NUM> is a circular member serving as a base (base stage) of the stage <NUM> and having a circular shape in a plan view, and is made of, for example, ceramic such as alumina (Al<NUM>O<NUM>). The base plate <NUM> has a disk-shaped base portion <NUM>, an outer peripheral wall <NUM> protruding upward along the outer periphery thereof, and a holding portion <NUM> protruding from the top surface of the base portion <NUM>.

The upper end of the outer peripheral wall <NUM> is fixed to the bottom surface of the middle plate <NUM>, and the holding portion <NUM> holds the control board <NUM> and the middle plate <NUM>. In the state in which the middle plate <NUM> is fixed on the base plate <NUM>, the space surrounded by the base portion <NUM>, the outer peripheral wall <NUM>, and the middle plate <NUM> is closed. The control board <NUM> is arranged in this space.

The control board <NUM> is a wiring board on which, for example, a microcomputer (not illustrated) that performs, for example, lighting control of the LED module <NUM> is mounted. The control board <NUM> is connected to the temperature controller <NUM> (see <FIG>) via, for example, a wire (not illustrated).

The middle plate <NUM> is a member arranged on the base plate <NUM> and having a circular shape in a plan view, and is made of, for example, copper (Cu). As an example, the middle plate <NUM> is fixed on the base plate <NUM> by, for example, screwing. The middle plate <NUM> is an example of a first cooling plate.

The middle plate <NUM> has a disk-shaped base portion <NUM>, an outer peripheral wall <NUM> protruding upward along the outer periphery, and a coolant flow path <NUM>. The coolant flow path <NUM> is an example of a first coolant flow path. The middle plate <NUM> is provided with a through hole (not illustrated) through which a wire connecting the control board <NUM> and the LED module <NUM> to each other passes. The through hole penetrates the middle plate <NUM> so as to connect the top surface and the bottom surface of the middle plate <NUM>.

A plurality of LED modules <NUM> is mounted on the top surface of the base portion <NUM>. In addition, the upper end of the outer peripheral wall <NUM> is fixed to the glass plate <NUM> using, for example, an adhesive.

The space above the base portion <NUM> is the mounting portion of the LED module <NUM>. Since the height of the outer peripheral wall <NUM> with respect to the base portion <NUM> is higher than the height of the LED module <NUM>, there is a space between the LED module <NUM> and the glass plate <NUM> mounted on the base portion <NUM>.

<FIG> illustrates only a portion of the coolant flow path <NUM>. However, in order to cool the LED module <NUM>, the coolant flow path <NUM> is actually installed inside the base portion <NUM> to cover substantially the entire base portion <NUM> in a plan view. A coolant 180A is supplied to the coolant flow path <NUM> via a pipe <NUM> as indicated by an arrow. As the coolant 180A, for example, water or Galden (registered trademark) may be used, and the coolant may be supplied to the coolant flow path by the pump <NUM> (see <FIG>).

Each LED module <NUM> has a plurality of LEDs 130A and lenses <NUM> attached to each LED 130A. The LED module <NUM> is an example of a heating source, and the LED 130A is an example of a light-emitting element. As the LED 130A, an LED that outputs near infrared light may be used. The lens <NUM> is attached to the light output portion of each LED 130A. The lens <NUM> is installed for adjusting the directivity of the light output from the LED 130A so as to suppress the dispersion of the light, thereby narrowing an emitting range. The lens <NUM> is made of, for example, glass or resin.

The LED module <NUM> is installed to heat the wafer W placed on the top plate <NUM> in order to adjust the temperature of the wafer W. The light (near infrared light) output from each LED 130A of the LED module <NUM> passes through the glass plate <NUM> and is absorbed into the top plate <NUM>, thereby heating the top plate <NUM>. As a result, the wafer W placed on the top surface of the top plate <NUM> can be heated.

The glass plate <NUM>, which is an example of a transmission member, is provided on the outer peripheral wall <NUM> of the middle plate <NUM>, and is fixed to the upper end of the outer peripheral wall <NUM> by, for example, an adhesive. A space is formed between the glass plate <NUM> and the LED module <NUM>. The glass plate <NUM> has a disk-shaped base portion <NUM> and a protrusion <NUM> protruding from the base portion <NUM> in a plan view. The top plate <NUM> is arranged on the glass plate <NUM>. The glass plate <NUM> and the top plate <NUM> are bonded to each other.

When the top plate <NUM> is placed on the glass plate <NUM>, the base portion <NUM> covers a groove 161A formed in the bottom surface side of the top plate <NUM> from below, and the protrusion <NUM> covers the groove 162A formed in the bottom surface side of the top plate <NUM> from below. As a result, the grooves 161A and 162A serve as a coolant flow path.

A connecting portion <NUM> is fixed to the bottom surface of the protrusion <NUM> via a rubber O-ring <NUM> by, for example, screwing. The protrusion <NUM> has a through hole 152A that communicates with the coolant flow path 172A in the connecting portion <NUM>. The through hole 152A communicates with the groove 162A in the top plate <NUM>.

The glass plate <NUM> is transparent in order to efficiently guide the light output from the LED module <NUM> to the top plate <NUM>. As the glass plate <NUM>, heat-resistant glass may be used such that it can withstand the heat generated by the wafer W and the heat generated by the nearinfrared light of the LED module <NUM>. For example, TEMPAX Float (registered trademark) may be used.

In the embodiment, a mode in which the glass plate <NUM> is used as an example of the transmission member has been described, but a transparent resin plate may be used instead of the glass plate <NUM>. As the transparent resin plate, for example, an acrylic or polycarbonate resin plate may be used.

The top plate <NUM> has the same shape as the glass plate <NUM> in a plan view, and has a placement surface 160A, a disk-shaped base portion <NUM>, a protrusion <NUM> protruding from the base portion <NUM> in a plan view, and a vacuum chuck <NUM>. The top plate <NUM> is an example of a second cooling plate. The placement surface 160A is the top surface of the top plate <NUM>, and the wafer W is placed on the placement surface 160A. Here, the shape configuration and function of the top plate <NUM> will be described first, and the material and thickness of the top plate <NUM> will be described later.

The top plate <NUM> has the groove 161A on the bottom surface side of the base portion <NUM>, and has the groove 162A on the bottom surface side of the protrusion <NUM>. The grooves 161A and 162A are formed so as to be recessed upward from the bottom surfaces of the base portion <NUM> and the protrusion <NUM>. The grooves 161A and 162A are covered with the glass plate <NUM> from the bottom surface side so as to serve as a coolant flow path. The grooves 161A and 162A are an example of a second coolant flow path.

The groove 161A is formed in a predetermined pattern (e.g., a spiral pattern) in the entire base portion <NUM> in a plan view, and all of the plurality of grooves 161A in the cross section illustrated in <FIG> communicates with each other and communicate with the groove 162A provided in the protrusion <NUM>.

Therefore, as indicated by the arrow, the coolant 180B flows into the groove 162A from the pipe <NUM> via the coolant flow path 172A in the connecting portion <NUM> and the through hole 152A in the glass plate <NUM>, flows into the grooves 161A from the groove 162A, and is discharged to the outside of the stage <NUM> via a discharge groove (not illustrated) similar to the groove 162A.

As the coolant 180B, for example, water or Galden (registered trademark), which is a colorless and light-transmissive liquid, is used, and is supplied to the coolant flow path by a pump (not illustrated) installed outside the inspection apparatus <NUM> (see <FIG>).

Since the bottom surface of the coolant flow path implemented by the grooves 161A and 162A is the glass plate <NUM>, the coolant 180B passes through the optical path of the light output from the LED module <NUM>. Therefore, a transparent coolant is preferable as the coolant 180A. This is to reduce the attenuation of light caused due to the coolant 180A such that more light output from the LED module <NUM> reaches the top plate <NUM>, thereby improving the heating efficiency.

The vacuum chuck <NUM> is installed on the placement surface 160A. A plurality of grooves illustrated as the vacuum chuck <NUM> in <FIG> is connected to a vacuum pump (not illustrated) through a vacuum pipe (not illustrated). By driving the vacuum pump, a wafer W can be suctioned to the placement surface 160A by the vacuum chuck <NUM>.

Further, the top plate <NUM> has a passage (not illustrated) through which a wire for the temperature sensor <NUM> (see <FIG>) for measuring the temperature of the wafer W passes, in addition to the components described above. Such a passage is formed inside the base portion <NUM> and the protrusion <NUM> while avoiding a vacuum pipe (not illustrated) connected to the grooves 161A and 162A and the vacuum chuck <NUM>.

In the inspection apparatus <NUM> including such a stage <NUM>, for example, when one of a plurality of electronic devices formed on the wafer W is selected as an inspection object so as to inspect electrical characteristics, the inspection may be performed as follows. In the state in which the wafer W is suctioned to the placement surface 160A by the vacuum chuck <NUM>, the wafer W is moved upward by the lifting mechanism <NUM>, and a load is applied to the electrode pads on the wafer W to press the probes 24a. Then, the LED module <NUM> located just below the electronic device, which is an inspection object, outputs light directly upward, and the coolant 180B is caused to flow through the coolant flow path constituted by the grooves 161A and 162A. At this time, the coolant 180A is caused to flow through the coolant flow path <NUM> in order to cool the LED module <NUM>.

The light output from the LED module <NUM> heats a portion of the top plate <NUM> located below the electronic device, which is an inspection object, such that the temperature of the electronic device of the inspection object becomes the set temperature in the inspection. As a result, the electronic device of the inspection object is heated. The electronic device itself generates heat when current flows therethrough. Thus, when the temperature of the electronic device becomes higher than the set temperature, the LED module <NUM> is turned off and the coolant 180B is supplied so as to absorb heat, thereby lowering the temperature of the electronic device.

Further, when the temperature of the electronic device becomes lower than the set temperature, the LED module <NUM> may be turned on and the supply of the coolant 180B may be stopped and heated so as to raise the temperature of the electronic device. By performing the control of turning-on and turning-off of the LED module <NUM> and the control of the supply amount of the coolant 180B at high speed, the temperature of the electronic device of the inspection object is adjusted to be within a predetermined temperature range (e.g., within ±<NUM> degrees C) with respect to the set temperature in the inspection.

Next, the material and thickness of the top plate <NUM> will be described. The top plate <NUM> is made of ceramic. The ceramic forming the top plate <NUM> is, for example, silicon carbide (SiC), a composite material of silicon carbide (SiC) and silicon (Si), or aluminum nitride (AlN). Here, a mode in which the ceramic is silicon carbide (SiC) will be described.

The reason why the above-mentioned ceramic is used as the top plate <NUM> is to obtain higher rigidity and higher thermal conductivity than those made of metal such as copper or aluminum. The high rigidity can provide a structure that can withstand the load during the inspection of the electrical characteristics (the structure advantageous in load resistance). Further, the high thermal conductivity can make it possible to cope with the heating of the wafer W and the heat absorption from the wafer W, which are performed at high speed during the inspection of the electrical characteristics.

The thickness of the top plate <NUM> is, for example, <NUM> to <NUM>. The thickness of the top plate <NUM> is the thickness of the portion in which the grooves 161A and 162A are not formed. The top plate <NUM> is formed to have a small thickness in order to realize a structure having a small heat capacity. This is because if the heat capacity is small, the temperature of the top plate <NUM> is easily raised by heating with the LED module <NUM>, and the temperature of the top plate <NUM> is easily lowered by the flow of the coolant 180B. Further, this is to make the structure capable of coping with the heating of the wafer W and the heat absorption from the wafer W, which are performed at high speed during the inspection of the electrical characteristics.

As described above, the top plate <NUM>, which has a three-dimensional structure including grooves 161A and 162A for cooling, a vacuum chuck <NUM>, and a passage for passing the wire for the temperature sensor, and a thin thickness, is a member, which is considerably difficult to manufacture.

Further, the placement surface 160A of the top plate <NUM> is mirror-polished, and a maximum height Rmax of the surface roughness (maximum peak to valley roughness height) of the placement surface 160A is, for example, <NUM> to <NUM>. The mirror polishing process is implemented, for example, by polishing the placement surface 160A of the top plate <NUM> with a polishing apparatus using slurry (suspension) containing polishing particles.

A load analysis showed that the top plate <NUM> having the above-described three-dimensional structure and a small thickness does not have sufficient load resistance when the top plate <NUM> is made of a metal such as aluminum or copper. In addition, it was possible to achieve high flatness of, for example, a level of <NUM> to <NUM> at the maximum height Rmax on the placement surface 160A by mirror polishing because the top plate <NUM> was made of ceramic that is highly rigid and is advantageous in load resistance.

Mirror polishing is performed to flatten the placement surface 160A and to reduce contact thermal resistance through top plate <NUM>, the placement surface 160A on which the wafer W is placed, and the bottom surface of the wafer W. Therefore, the maximum height Rmax of the placement surface 160A on which the wafer W is placed is set to be within the range described above. The contact thermal resistance is a resistance value obtained by dividing a surface temperature difference ΔT of two objects by a heat flow rate Q when the two objects having different temperatures (here, the top plate <NUM> and the wafer W) are brought into contact with each other.

During the inspection of the electrical characteristics, the wafer W is placed on the placement surface 160A, the contact thermal resistance between the top plate <NUM> and the wafer W through the placement surface 160A and the bottom surface of the wafer W is reduced to perform the heating of the wafer W and the absorption of heat from the wafer W at high speed. Therefore, heat is easily transferred between the top plate <NUM> and the wafer W.

When the contact thermal resistance between the top plate <NUM> and the wafer W is large, if the quantity of heat in an electronic device of the inspection object is large, the cooling performed by the heat absorption cannot reach the quantity of heat in the electronic device of the inspection object. Thus, the temperature of the electronic device rises too high and cannot be adjusted within a predetermined temperature range. On the contrary, when the contact thermal resistance between the top plate <NUM> and the wafer W is large, if it is desired to rapidly heat the electronic device of the inspection object, the heat transfer from the top plate <NUM> to the wafer W is delayed. Thus, the temperature of the electronic device is too low and cannot be adjusted within a predetermined temperature range. In order to suppress these problems, the placement surface 160A is mirror-polished to reduce the contact thermal resistance between the top plate <NUM> and the wafer W.

In order to quickly control the temperature of a wafer W having a quantity of heat of, for example, about <NUM> W to several hundreds of W or more, heating and heat absorption may be switched at high speed. Thus, the small contact thermal resistance between the top plate <NUM> and the wafer W is very significant. From this point of view, the placement surface 160A of the top plate <NUM> is mirror-polished to set the maximum height Rmax of the placement surface 160A to, for example, <NUM> to <NUM>. Since the bottom surface of the wafer W has the maximum height of, for example, about <NUM> to <NUM> and is sufficiently flat, mirror polishing is performed on the placement surface 160A.

The larger the contact area between the placement surface 160A of the top plate <NUM> and the bottom surface of the wafer W, the smaller the contact thermal resistance between the top plate <NUM> and the wafer W. When the maximum height Rmax of the placement surface 160A is within a small value range of, for example, <NUM> to <NUM>, the area of the contact portion increases, and the gap between the placement surface 160A and the bottom surface of the wafer W decreases. Thus, sufficiently small contact thermal resistance is obtained. When the area of the contact portion increases, the suction force of the vacuum chuck <NUM> becomes strong, and thus the misalignment (contact misalignment) of the probe 24a with respect to the electrode pads of the electronic device is difficult to occur when a high load is applied.

Here, the following simulation was performed before setting the lower limit value and the upper limit value of the maximum height Rmax of the placement surface 160A to the values described above.

First, the maximum height Rmax of the placement surface 160A of the top plate <NUM> was examined by simulation.

The target value of the maximum height Rmax of the mirror-polished placement surface 160A of the top plate <NUM> was set to <NUM> or less, and the contact thermal resistance when the maximum height Rmax was <NUM> was obtained. As simulation conditions, the thermal conductivity of the top plate <NUM> was set to <NUM> W/mK, the maximum height Rmax of the bottom surface of the wafer W was set to <NUM>, the size of the electronic device was set to <NUM>×<NUM>, the thermal conductivity of the wafer W was set to <NUM> W/mK, and the load applied to the wafer W was set to <NUM> kgf.

As a result, the contact thermal resistance between the wafer W and the top plate <NUM> having the mirror-polished placement surface 160A was <NUM> degrees C/W. This indicates that, when a quantity of heat of <NUM> W is applied to the top plate <NUM>, the temperature difference ΔT between the top plate <NUM> and the wafer W is <NUM> degrees C, which is a good result.

In addition, a simulation was performed using a top plate having a top surface, which was not mirror-polished, as a comparative top plate, and the following conditions were set. The maximum height Rmax of the top surface of the comparative top plate was set to <NUM>, the thermal conductivity of the comparative top plate was set to <NUM> W/mK, the maximum height Rmax of the bottom surface of the wafer W was set to <NUM>, and the size of the electronic device was set to <NUM>×<NUM>, the thermal conductivity of the wafer W was set to <NUM> W/mK, and the load applied to the wafer W was set to <NUM> kgf.

As a result, the contact thermal resistance between the comparative top plate and the wafer W was <NUM> degrees C/W. This indicates that when the heat quantity of <NUM> W is applied to the comparative top plate, the temperature difference ΔT between the comparative top plate and the wafer W is <NUM> degrees C, which is a value at a level at which it is difficult to control heating and heat absorption of the wafer W.

From the above simulations, it was found that when the top plate <NUM> having the mirror-polished placement surface 160A, the contact thermal resistance was about <NUM>/<NUM> of that obtained in the case in which the comparative top plate was used. From this result, the target value of the contact thermal resistance between the top plate <NUM> and the wafer W was set to <NUM> degrees C/W or less. Then, the following tests were conducted.

<FIG> are views showing images of surfaces and surface roughness distributions (cross-sectional curves) on exemplary processed SiC plates.

<FIG> shows an image of the surface of a SiC plate, on which a grinding process is performed, taken at a magnification of <NUM> times using an electron microscope, and <FIG> shows a surface roughness distribution (a cross-sectional curve) of the surface of a SiC plate on which a grinding process is performed. The grinding was performed by a grinder using a grinding wheel. As shown in <FIG>, the surface was rough, and as shown in <FIG>, the maximum height Rmax (the difference between the highest peak and the lowest valley) was <NUM> as indicated by the double-headed arrow.

In addition, <FIG> shows an image of the surface of a mirror-polished SiC plate taken at a magnification of <NUM> times using an electron microscope, and <FIG> shows a surface roughness distribution (a cross-sectional curve) of the surface of a mirror-polished SiC plate. As shown in <FIG>, the surface is very flat, and concave portions due to grain boundaries are visible. Further, as shown in <FIG>, the maximum height Rmax was at a level of about several tens of nm, and a value of <NUM> or less was obtained. In the measurement of the maximum height Rmax on the mirror-polished surface, the concave portions due to the SiC grain boundary were excluded.

As described above, when the SiC plate is mirror-polished, a maximum height Rmax of <NUM> or less is obtained. Therefore, the lower limit of the maximum height Rmax of the placement surface 160A of the top plate <NUM> was set to <NUM>.

In addition, the upper limit of the maximum height Rmax of the placement surface 160A of the top plate <NUM> was determined as follows. When the contact thermal resistance between the top plate <NUM> and the wafer W is <NUM> degrees C/W, which is the upper limit of the target range, the temperature difference ΔT between the top plate <NUM> and the wafer W when a heat quantity of <NUM> W is applied to the top plate <NUM> (in this case, the temperature difference ΔT due to the temperature of the top plate <NUM> being higher than the temperature of the wafer W) is <NUM> degrees C.

In the case in which the maximum height Rmax of the bottom surface of the wafer W was <NUM> and the maximum height Rmax of the placement surface 160A of the top plate <NUM> was <NUM>, when the conductivity of the gas (air) interposed between the wafer W and the top plate <NUM> was assumed as <NUM> W/mK, the contact thermal resistance was calculated as <NUM> degrees C/W. The calculation was performed in the state in which the contact area between the electronic device and the probe 24a to was set to <NUM>×<NUM> and the load applied to the electronic device was set to <NUM>.

Thus, when the maximum height Rmax of the placement surface 160A of the top plate <NUM> was set to <NUM>, the contact thermal resistance was about <NUM> degrees C/W. Therefore, the upper limit of the maximum height Rmax of the placement surface 160A of the top plate <NUM> was set to <NUM>.

As described above, since the stage <NUM> is highly rigid by being made of ceramic and includes the top plate <NUM> having the mirror-polished placement surface 160A, the contact thermal resistance between the top plate <NUM> and the wafer W through the placement surface 160A and the bottom surface of the wafer W is reduced. Reduction of the contact thermal resistance between the top plate <NUM> and the wafer W means reduction of the contact thermal resistance between the stage <NUM> and the wafer W.

Therefore, according to the embodiment, it is possible to provide the stage <NUM> and the inspection apparatus <NUM>, which are capable of reducing the contact thermal resistance between the stage <NUM> and the wafer W. In addition, since the contact thermal resistance between the stage <NUM> and the wafer W is low, it is possible to perform the heating of the wafer W and the absorption of heat from the wafer W at high speed, and thus to perform the inspection with high throughput.

Further, since the top plate <NUM> is made of ceramic and has high rigidity, it is possible to obtain good flatness in mirror polishing even if the top plate <NUM> is made thin in order to reduce the heat capacity. The top plate <NUM> made of ceramic is advantageous in load resistance compared with that made of metal.

Further, since the top plate <NUM> vacuum-suctions the wafer W using the vacuum chuck <NUM>, the attraction force between the top plate <NUM> and the wafer W becomes stronger when the contact thermal resistance between the top plate <NUM> and the wafer W is reduced by performing mirror polishing on the placement surface 160A (i.e., when the space gap becomes small). As a result, the misalignment (contact misalignment) of the probes 24a with respect to the electrode pads of the electronic device is difficult to occur when a high load is applied.

Further, since the maximum height Rmax of the placement surface is <NUM> to <NUM>, the contact thermal resistance between the top plate <NUM> and the wafer W becomes <NUM> degrees C/W to about <NUM> degrees C/W. Therefore, it is possible to provide the stage <NUM> having a configuration capable of performing heating of the wafer W and absorption of heat from the wafer W at high speed.

Further, since the thickness of the top plate <NUM> is <NUM> to <NUM>, it is possible to provide the stage <NUM> in which the rigidity of the top plate <NUM> is ensured and the heat capacity is reduced.

Further, the ceramic forming the top plate <NUM> is made of, for example, silicon carbide (SiC), a composite material of silicon carbide (SiC) and silicon (Si), or aluminum nitride (AlN). Thus, it is possible to provide the stage <NUM> including the top plate <NUM>, which is more rigid than metal and has a placement surface 160A suitable for mirror polishing.

In the above description, the mode in which a wafer W having a plurality of electronic devices formed thereon is placed on the top plate <NUM> has been described. However, a plurality of electronic devices separated by dicing may be placed on the placement surface 160A of the top plate <NUM> in the state of being arranged on a predetermined substrate.

In the above description, the mode in which the base portion <NUM> of the base plate <NUM>, the base portion <NUM> of the middle plate <NUM>, the base portion <NUM> of the glass plate <NUM>, and the base portion <NUM> of the top plate <NUM> are disk-shaped has been described. However, the base portions <NUM>, <NUM>, <NUM>, and <NUM> may be rectangular plate-shaped members in a plan view. In this case, the outer peripheral wall <NUM> of the middle plate <NUM> may be a rectangular wall in a plan view.

In the foregoing, the configuration in which the top plate <NUM> has the grooves 161A and 162A on respective bottom surface sides of the base portion <NUM> and the protrusion <NUM>, and the coolant flow path is obtained by covering the grooves 161A and 162A using the glass plate <NUM> from the bottom surface sides thereof has been described above. However, the top plate <NUM> may have a coolant flow path provided inside the top plate <NUM> instead of the grooves 161A and 162A. This coolant flow path is located between the top surface and the bottom surface in the vertical direction (thickness direction) of the top plate <NUM>.

<FIG> is a cross-sectional view illustrating an exemplary configuration of a stage <NUM> according to an embodiment. The stage <NUM> is obtained by applying a black coating <NUM> to the bottom surface of the top plate <NUM> of the stage <NUM> (shown in <FIG>) of the unclaimed example.

The black coating <NUM> is an example of a heat absorption film, and is applied to the inside of the groove 161A in the base portion <NUM> of the top plate <NUM> and the portions that are in contact with the glass plate <NUM>. The black coating <NUM> is provided in order to more efficiently absorb the light, which is output from the LED module <NUM> and transmitted through the glass plate <NUM>, on the bottom surface of the top plate <NUM>, and to more efficiently heat the top plate <NUM>. By applying this black coating <NUM>, it is possible to more efficiently heat the electronic devices on a wafer W.

As the black coating <NUM>, a water-based paint or a fluororesin coating containing black ceramic powder having water resistance and heat resistance may be applied. The top plate <NUM> having the black coating <NUM> applied thereto may be bonded onto the glass plate <NUM>.

As described above, according to the embodiment, by applying the black coating <NUM> to the bottom surface of the top plate <NUM>, it is possible to provide the stage <NUM>, which is capable of improving heating efficiency by more efficiently absorbing heat into the top plate <NUM>, in addition to suppressing the displacement of the top plate <NUM> due to a load.

In the embodiment, the mode in which the black coating <NUM> as an example of the heat absorption film is applied to the bottom surface of the top plate <NUM> has been described. However, the film is not limited to the black coating <NUM> as long as the film is capable of increasing the amount of the heat absorption of the top plate <NUM>. The color may be other than black (e.g., dark gray), and the material of the heat absorption film may be other than those described above.

Claim 1:
A stage (<NUM>, <NUM>) configured to hold thereon an inspection object (W) having an electronic device pressed against a contact terminal (24a) of a probe card (<NUM>) of an inspection apparatus (<NUM>) by applying a load, and including a first cooling plate (<NUM>) including a first coolant flow path (<NUM>) formed in the first cooling plate (<NUM>),
a heating source (<NUM>) mounted on the first cooling plate (<NUM>) and configured to heat the inspection object (W), and
a transmission member (<NUM>) installed on the heating source (<NUM>) and configured to transmit light output from the heating source (<NUM>); the stage (<NUM>, <NUM>) being characterized by:
a second cooling plate (<NUM>) installed on the transmission member (<NUM>), including a placement surface (160A) configured to vacuum-suction the inspection object (W) and a second coolant flow path (161A, 162A), made of ceramic, and subjected to a mirror polishing process on the placement surface (160A); and
a heat absorption film (<NUM>) installed on a bottom surface of the second cooling plate (<NUM>) and formed by applying a water-based paint or a fluororesincontaining ceramic powder having water resistance and heat resistance,
wherein the placement surface (160A) of the second cooling plate (<NUM>) has a maximum height (Rmax) of the surface roughness of <NUM> to <NUM>,
wherein the second coolant flow path (161A, 162A) is formed inside the second cooling plate (<NUM>),
wherein the second cooling plate (<NUM>) has a thickness of <NUM> to <NUM>, and wherein the ceramic forming the second cooling plate (<NUM>) is silicon carbide, a composite material of silicon carbide and silicon, or aluminum nitride.