Apparatus and method for reducing wafer warpage

An apparatus and a method for reducing wafer warpage are provided. The method includes positioning a mold wafer structure on a stage. The mold wafer structure includes a mold layer and a stack structure positioned on a wafer. The stage includes a center region and an edge region adjacent the center region. Warpage information of the mold wafer structure is obtained. The mold wafer structure is heated by the stage based on the warpage information to reduce a warpage of the mold wafer structure. A temperature of the center region and a temperature of the edge region are different from each other. An operation test is performed on the stack structure.

CROSS-REFERENCE TO RELATED APPLICATION

1. TECHNICAL FIELD

Exemplary embodiments of the present inventive concept relate to an apparatus for reducing wafer warpage, and more particularly to a method for reducing wafer warpage.

2. DISCUSSION OF RELATED ART

A wafer might not be fixed to equipment during assembly and test processes and thus wafer warpage may occur after a mold process. Wafer warpage may result from a difference in respective thermal expansion coefficients of a film material, a mold material, and a stack structure bonding material of a silicon device.

SUMMARY

An exemplary embodiment of the present inventive concept provides an apparatus for reducing wafer warpage.

An exemplary embodiment of the present inventive concept provides a method for reducing wafer warpage.

A method for reducing wafer warpage according to an exemplary embodiment of the present inventive concept includes positioning a mold wafer structure on a stage. The mold wafer structure includes a mold layer and a stack structure positioned on a wafer. The stage includes a center region and an edge region adjacent the center region. Warpage information of the mold wafer structure is obtained. The mold wafer structure is heated by the stage based on the warpage information to reduce a warpage of the mold wafer structure. A temperature of the center region and a temperature of the edge region are different from each other. An operation test is performed on the stack structure.

A method for reducing wafer warpage according to an exemplary embodiment of the present inventive concept includes forming a stack structure on a wafer. A mold layer substantially surrounding the stack structure is formed on the wafer. A mold wafer structure including the wafer, the stack structure and the mold layer is positioned on a test stage. The test stage includes a first ring heater having a first radius and a second ring heater having a second radius greater than the first radius and substantially surrounding the first ring heater. Warpage of the mold wafer structure is reduced by heating the mold wafer structure through the first ring heater and the second ring heater based on warpage information of the mold wafer structure. Temperatures of the first and second ring heaters are different from each other.

DETAILED DESCRIPTION

An apparatus for reducing wafer warpage according to some exemplary embodiments of the present inventive concept will be described in more detail below with reference toFIGS. 1 to 5.

FIG. 1is a front view illustrating an apparatus for reducing wafer warpage according to an exemplary embodiment of the present inventive concept.FIG. 2is a top view illustrating the apparatus for reducing wafer warpage ofFIG. 1.FIG. 3is a diagram illustrating the apparatus for reducing wafer warpage ofFIG. 1.FIG. 4is a front view illustrating operation of the apparatus for reducing wafer warpage ofFIG. 1.FIG. 5is a front view illustrating operation of the apparatus for reducing wafer warpage ofFIG. 1.

Referring toFIG. 1, an apparatus for reducing wafer warpage according to an exemplary embodiment of the present inventive concept may include a stage100.

The stage100may test a mold wafer structure10. As an example, the mold wafer structure10may be disposed on and/or connected to the stage100. The mold wafer structure10may include a wafer W, a stack structure S1, and a bump B. The wafer W may be a semiconductor substrate. The wafer W may include at least one of silicon, germanium, and silicon germanium. However, exemplary embodiments of the present inventive concept are not limited thereto.

The stack structure S1may be stacked on the wafer W. The stack structure S1may be a structure in which chips are stacked and overlap each other in a plurality of layers. The stack structure S1may include a through silicon via (TSV) structure.

A mold layer M may substantially cover upper surfaces of the stack structure S1and the wafer W. Since the mold layer M covers the upper surfaces of the stack structure S1and the wafer W, the stack structure S1and the wafer W may be fixed to each other by the mold layer M. Thus, the stack structure S1having a relatively large aspect ratio may be supported by the mold layer M.

The bump B may be connected to the stack structure S1and may be formed on a lower surface of the wafer W. As an example, the stack structure S1and the bump B may penetrate through the wafer W and may be electrically connected to each other. The bump B may be a connection terminal, which may connect the mold wafer structure10to another structure.

The mold wafer structure10may be mounted on the stage100. A portion (e.g., a lower surface) of the mold wafer structure10opposite the upper surface of the wafer W may face in a downward direction and may be in direct contact with the stage100. The mold wafer structure10may be mounted on the stage100. The bump B may face and/or protrude in an upward direction opposite the lower surface of the wafer W, which may be in direct contact with the stage.

The stage100may include a stage housing110, a suction hole120, and a heater130.

The stage housing110may be a portion of the stage100forming an outer shape of the stage100. The stage housing110may support the mold wafer structure10mounted on the stage100. The stage housing110may include the suction hole120and the heater130therein. The stage housing110may have an upper surface which is large enough to mount the mold wafer structure10. The upper surface of the stage housing110may have a substantially circular shape. However, exemplary embodiments of the present inventive concept are not limited thereto.

The suction hole120may be formed in the upper surface of the stage housing110. The suction hole120may be a structure which adsorbs an object mounted on the upper surface of the stage housing110to the stage100. As an example, the suction hole120may fix the object formed on the upper surface of the stage100and mounted on the upper surface by the vacuum. As an example, the mold wafer structure10may be attached to the upper surface of the stage housing110through the suction hole120.

The heater130may be positioned inside the stage housing110. The heater130may heat the mold wafer structure10mounted on the stage100within the stage housing110. The heater130may heat the mold wafer structure10from a lower portion of the mold wafer structure10.

Referring toFIG. 2, the heater130may be a ring shaped heater.

The heater130may include a plurality of ring heaters (e.g., ring heaters131and ring heaters133). For example, ring heaters131a,131band131c, and ring heaters133a,133band133cmay be concentric circle shapes having substantially a same center. The ring heaters131a-131c,133a-133cmay have different radii from each other. As an example, each of the ring heaters131a-131c,133a-133cmay have first to sixth radii R1-R6.

As an example, a first ring heater131amay have a first radius R1, and a second ring heater131bmay have a second radius R2. A third ring heater131cmay have a third radius R3, and a fourth ring heater133amay have a fourth radius R4. A fifth ring heater133bmay have a fifth radius R5, and a sixth ring heater133cmay have a sixth radius R6.

The first to sixth radii R1-R6may be different from one another. As an example, the first radius R1may be less than the second radius R2, and the second radius R2may be less than the third radius R3. The third radius R3may be less than the fourth radius R4. The fourth radius R4may be less than the fifth radius R5. The fifth radius R5may be less than the sixth radius R6.

Although the shapes of the first to sixth ring heaters may be substantially circular, exemplary embodiments of the present inventive concept are not limited thereto. For example, shapes of the first to sixth ring heaters might not be circular.

While there may be a number of ring heaters in the apparatus for reducing wafer warpage according to some exemplary embodiments of the present inventive concept, exemplary embodiments of the present inventive concept are not limited thereto. The number of the ring heaters is not specifically limited to a particular number.

The heater130may include a plurality of regions. For example, the heater130may include a first region H1and a second region H2. The first region H1may be a region where the first to third ring heaters131are positioned. The second region H2may be a region where the fourth to sixth ring heaters133are positioned.

The first to sixth ring heaters (e.g., ring heaters131and ring heaters133) may apply heat to the lower surface of the mold wafer structure10from the lower portion of the mold wafer structure10. As an example, the first to sixth ring heaters may substantially evenly provide heat from a center to an edge of the mold wafer structure10.

The stage100including the first to sixth ring heaters may include a center region and an edge region on the upper surface. The center region may be a region corresponding to the first region H1including the first to third ring heaters131. For example, the first region H1and the center region may overlap each other. The edge region may be a region corresponding to the second region H2including the fourth to sixth ring heaters133. As an example, the second region H2and the edge region may overlap each other.

Referring toFIG. 3, the apparatus for reducing wafer warpage according to an exemplary embodiment of the present inventive concept may include a controller200.

The controller200may receive warpage information (e.g., from a source that is external to the apparatus for reducing warpage). The warpage information may indicate warping degree of the mold wafer structure10(see, e.g.,FIG. 1). For example, the warpage information may be information indicating which region of the mold wafer structure10is warped and how much the region is warped.

The controller200may control whether each of the first to sixth ring heaters is on or off based on the received warpage information. As an example, the controller200may control which ring heater(s) is/are on, and which ring heaters is/are off, based on the warpage information.

The first to third ring heaters131positioned in the first region H1may be substantially simultaneously turned on or substantially simultaneously turned off. Similarly, the fourth to sixth ring heaters133positioned in the second region H2may be substantially simultaneously turned on or substantially simultaneously turned off.

Operation of an apparatus for reducing wafer warpage according to an exemplary embodiment of the present inventive concept will be described in more detail below with reference toFIGS. 3 to 5.

Referring first toFIG. 4, when the mold wafer structure10is shaped with a relatively low center region and a relatively high edge region, the first to third ring heaters131of the first region H1may be off, and the fourth to sixth ring heaters133of the second region H2may be on. Thus, the warpage of the mold wafer structure10may be reduced or eliminated by the heat applied to the edge region. Since a height of the edge region of the mold wafer structure10may be lowered, the warpage with respect to the center region may be reduced or eliminated. Thus, the edge region of the mold wafer structure10may be substantially completely adsorbed through at least one suction hole120of the stage100.

Referring toFIG. 5, when the mold wafer structure10is shaped with a relatively high center region and a relatively low edge region, the first to third ring heaters131of the first region H1may be on, and the fourth to sixth ring heaters133of the second region H2may be off. Thus, the warpage of the mold wafer warpage10may be reduced or eliminated by the heat applied to the center region. Since a height of the center region of the mold wafer structure10may be lowered, the warpage with the edge region may be reduced or eliminated. Thus, the center region of the mold wafer structure10may be substantially completely adsorbed through at least one suction hole120of the stage100.

Referring toFIG. 3, the controller200may determine which ring heater(s) is/are to be on and which ring heater(s) is/are to be off, among the first to third ring heaters131and the fourth to sixth ring heaters133according to the warpage information of the mold wafer structure10. Thus, the warpage of the mold wafer structure10may be reduced or eliminated.

Referring toFIGS. 3 to 5, the first to sixth ring heaters (e.g., ring heaters131and133) may be turned on or off individually, as desired. Additionally, an apparatus for reducing wafer warpage according to some exemplary embodiments of the present inventive concept may individually control a temperature of each ring heater. For example, each ring heater may be controlled to be at a different temperature from each other while all the ring heaters are on.

Referring toFIG. 4, when the mold wafer structure10is shaped with the relatively low center region and the relatively high edge region, the first to third ring heaters131of the first region H1may be on at a first temperature and the fourth to sixth ring heaters133of the second region H2may be on at a second temperature. As an example, the first temperature may be lower than the second temperature. As an example, the center region may be heated at a relatively lower temperature, and the edge region may be heated at a relatively higher temperature.

As an example, the warpage of the mold wafer structure10may be reduced or eliminated with the relatively greater heat applied to the edge region. Thus, because a height of the edge region of the mold wafer structure10may be lowered, the warpage with respect to the center region may be reduced or eliminated. Thus, the edge region of the mold wafer structure10may be substantially completely adsorbed through at least one suction hole120of the stage100.

Referring toFIG. 5, when the mold wafer structure10is shaped with the relatively high center region and the relatively low edge region, the first to third ring heaters131of the first region H1may be on at a third temperature and the fourth to sixth ring heaters133of the second region H2may be on at a fourth temperature. As an example, the third temperature may be higher than the fourth temperature. Thus, the center region may be heated at a relatively higher temperature and the edge region may be heated at a relatively lower temperature.

Thus, the warpage of the mold wafer structure10may be reduced or eliminated with the relatively greater heat applied to the center region than is applied to the edge region. As an example, since a height of the center region of the mold wafer structure10may be lowered, the warpage with respect to the edge region may be reduced or eliminated. Thus, the center region of the mold wafer structure10may be substantially completely adsorbed through at least one suction hole120of the stage100.

An apparatus for reducing wafer warpage according to an exemplary embodiment of the present inventive concept will be described in more detail below with reference toFIG. 6. Elements or operations described with reference toFIG. 6may be substantially the same as those described above with reference toFIGS. 1 to 5and thus duplicative descriptions may be omitted.

FIG. 6is a front view illustrating an apparatus for reducing wafer warpage according to an exemplary embodiment of the present inventive concept.

Referring toFIG. 6, the second region H2may include a plurality of regions. As an example, the second region H2may include a second-first region H2-1and a second-second region H2-2.

The second-first region H2-1may be positioned between the first region H1and the second-second region H2-2. As an example, the second-first region H2-1may be in contact with an external area of the first region H1and may substantially surround the first region H1. An outer surface of the second-first region H2-1may be substantially surrounded by the second-second region H2-2, and the second-first region H2-1may be in contact with the second-second region H2-2.

The second-second region H2-2may be positioned outside the second-first region H2-1. As an example, the second-second region H2-2may be a region which is in contact with the second-first region H2-1, and substantially surrounds the second-first region1-12-1. The second-second region H2-2may be a region which substantially surrounds the first region H1but is not in contact with the first region H1.

The second-first region H2-1may include the fourth and fifth ring heaters133a,133b. The second-second region H2-2may include the sixth ring heater133c. However, exemplary embodiments of the present inventive concept are not limited thereto. According to an exemplary embodiment of the present inventive concept, only the fourth ring heater133amight be included in the second-first region H2-1, and the fifth ring heater133band the sixth ring heater133cmight be included in the second-second region H2-2. As an example, when the apparatus for reducing wafer warpage according to some exemplary embodiments of the present inventive concept includes three or more regions, a number of the heaters within each region is not limited to a particular number of heaters.

The fourth and fifth ring heaters133a,133bin the second-first region H2-1and the sixth ring heater133cin the second-second region H2-2may be controlled to be turned on or off by the controller200ofFIG. 3. For example, the controller200(see, e.g.,FIG. 3) may turn on or off the ring heaters in the first region H1, the second-first region H2-1, and the second-second region H2-2based on warpage information (see, e.g.,FIG. 3).

The controller200(see, e.g.,FIG. 3) may control temperatures of the ring heaters in the first region H1, the second-first region H2-1, and the second-second region H2-2based on warpage information (see, e.g.,FIG. 3). When the edge region is relatively high (see, e.g.,FIG. 4), the mold wafer structure10may be heated so that the first region H1, the second-first region H2-1, and the second-second region H2-2have sequentially higher temperatures.

When the center region is relatively high (see, e.g.,FIG. 5), the mold wafer structure10may be heated so that the first region H1, the second-first region H2-1and the second-second region H2-2have sequentially lower temperatures.

According to some exemplary embodiments of the present inventive concept the heater may have three regions; however, exemplary embodiments of the present inventive concept are not limited thereto. The apparatus for reducing wafer warpage according to some exemplary embodiments of the present inventive concept may include three or more regions, and the three or more regions may be turned on or off separately based on warpage information (see, e.g.,FIG. 3) and temperatures of each of the three or more regions may be separately controlled (e.g., by the controller200). Thus, relatively precise warpage reducing operations may be performed.

An apparatus for reducing wafer warpage according to an exemplary embodiment of the present inventive concept will be described in more detail below with reference toFIGS. 7 and 8. Elements or operations described with reference toFIGS. 7-8may be substantially the same as those described above and thus duplicative descriptions may be omitted.

FIG. 7is a front view illustrating an apparatus for reducing wafer warpage according to an exemplary embodiment of the present inventive concept.FIG. 8is a top view illustrating operation of the apparatus for reducing wafer warpage ofFIG. 7.

Referring toFIG. 7, an apparatus for reducing wafer warpage according to an exemplary embodiment of the present inventive concept may include a heating lamp300.

The heating lamp300may be positioned on or above the stage100. The heating lamp300may be positioned above the mold wafer structure10mounted on the stage100. A portion of the mold layer M of the mold wafer structure10may be in direct contact with the upper surface of the stage100, and the bump B may be exposed in an upward direction opposite the upper surface of the stage100. The bump B may include a plurality of bumps.

The heating lamp300may apply heat to the portion of the mold layer M including the bump B of the mold wafer structure10. The heating lamp300may reduce wafer warpage by applying heat to a relatively narrow region in a spotlight form.

The heating lamp300may include a heating source310and a lamp arm320.

The heating source310may be a lamp portion which directly applies heat to the mold wafer structure10. The heating source310may be, for example, a halogen lamp. However, exemplary embodiments are not limited thereto. The heating source310need not be limited to a specific type of heating source. The heating source310may be connected with the lamp arm320.

The lamp arm320may be connecting to the heating source310and may suspend the heating source310above the mold wafer structure10. The lamp arm320may move in an XY plane above the mold wafer structure10. The lamp arm320may move also in Z axis, which may control a heating intensity of the heating source310with respect to the mold wafer structure10. Thus, according to the Z axis movement of the lamp arm320, the heating intensity applied to the mold wafer structure10may be controlled.

The heating lamp300may reduce wafer warpage without individually heating each region of the stage100. That is, the heating lamp300may further reduce horizontally asymmetrical warpage of the mold wafer structure10. Thus, by using the heating lamp300in addition to the ring shaped heater, effects of reducing wafer warpage may be further increased.

Referring toFIG. 8, the heating lamp300may apply the heat to a spotlight form of a heating region11on the upper surface of the mold wafer structure10. The heating region11may be positioned anywhere by the lamp arm320as long as it is the upper surface of the mold wafer structure10. Although the heating region11is illustrated to be in circular shape, exemplary embodiments of the present inventive concept are not limited thereto. Further, according to a distance with the heating lamp300and a size of the heating source310, a size of the heating region11may be varied.

An apparatus for reducing wafer warpage according to an exemplary embodiment of the present inventive concept will be described in more detail below with reference toFIG. 9. Elements or operations described with reference toFIG. 9may be substantially the same as those described above and thus duplicative descriptions may be omitted.

FIG. 9is a front view illustrating an apparatus for reducing wafer warpage according to an exemplary embodiment of the present inventive concept.

Referring toFIG. 9, an apparatus for reducing wafer warpage according to an exemplary embodiment of the present inventive concept may include bar heaters135a-135h.

The bar heaters135a-135hmay be positioned within the stage100. As an example, the bar heaters135a-135hmay be positioned within the stage housing110. The bar heaters135a-135hmay overlap with the first to sixth ring heaters (see, e.g., ring heaters131and133described above in more detail). The bar heaters135a-135hmay each be bar shaped heaters (e.g., straight bar shaped heaters). The bar heaters135a-135hmay reduce horizontally asymmetrical warpage.

A plurality of bar heaters135a-135hmay be provided. As an example, the bar heaters may include a first bar heater135a, a second bar heater135b, a third bar heater135c, a fourth bar heater135d, a fifth bar heater135e, a sixth bar heater135f, a seventh bar heater135gand an eighth bar heater135h; however, exemplary embodiments of the present inventive concept is not limited thereto. The bar heaters135a-135hmay be positioned in a substantially horizontally symmetrical arrangement. The bar heaters135a-135hmay be disposed on the first to sixth ring heaters; however, exemplary embodiments of the present inventive concept is not limited thereto. For example, the bar heaters135a-135hmay be positioned under the first to sixth ring heaters (see, e.g., ring heaters131and133described above in more detail).

The bar heaters135a-135hmay be controlled to be turned on or off by the controller200(see, e.g.,FIG. 3). As an example, the bar heaters135a-135hmay each individually be turned on or off according to a degree of warpage of corresponding portions. For example, when portions corresponding to the first to third bar heaters135a-135cand the seventh bar heater135hof the mold wafer structure10are relatively higher than the other portions, the controller200may turn on the first to third bar heaters135a-135cand the seventh bar heater135g, and turn off the fourth to sixth bar heaters135d-135fand the eighth bar heater135h.

As an example, warpage may be reduced or eliminated by turning on all the bar heaters135a-135h. The temperatures of each of the bar heaters135a-135hmay be individually controlled to be different from each other. As an example, when the portions corresponding to the first to third bar heaters135a-135cand the seventh bar heater135gof the mold wafer structure10are relatively higher than the other portions, the controller200may turn on the first to third bar heaters135a-135cand the seventh bar heater135gat a first temperature, and turn on the other fourth to sixth bar heaters135d-135fand the eighth bar heater135hat a second temperature, which may be different from the first temperature. For example, the first temperature may be higher than the second temperature.

Thus, the apparatus for reducing wafer warpage according to some exemplary embodiments of the present inventive concept may reduce horizontally asymmetrical warpage and may reduce warpage according to a radius of the heaters according to an exemplary embodiment of the present inventive concept.

An apparatus for reducing wafer warpage according to an exemplary embodiment of the present inventive concept will be described in more detail below with reference toFIGS. 10 and 11. Elements or operations described with reference toFIGS. 10 and 11may be substantially the same as those described above and thus duplicative descriptions may be omitted.

FIG. 10is a front view illustrating an apparatus for reducing wafer warpage according to an exemplary embodiment of the present inventive concept.FIG. 11is a diagram illustrating the apparatus for reducing wafer warpage ofFIG. 10.

Referring toFIGS. 10 and 11, an apparatus for reducing wafer warpage according to an exemplary embodiment of the present inventive concept may include a sensor module400.

The sensor module400may be positioned above the stage100. The sensor module400may be positioned above the mold wafer structure10mounted on the stage100. A bottom surface of the mold layer M of the mold wafer structure10may be in direct contact with the upper surface of the stage100, and the bump B may be exposed in an upward direction opposite the bottom surface of the mold layer M.

The sensor module400may measure a displacement of a portion of the mold wafer structure10where the bump B (e.g., the bump B may include a plurality of bumps) is positioned. Thus, the sensor module400may generate warpage information of the mold wafer structure10.

The sensor module400may include a displacement sensor410and a sensor arm420.

The displacement sensor410may measure a displacement of a surface (e.g., an upper surface) of the mold wafer structure10. For example, the displacement sensor410may measure a displacement Hc of a center region and a displacement He of an edge region of the mold wafer structure10. Thus, warpage information of the mold wafer structure10may be obtained. As an example, the displacement sensor410may generate whole warpage information by measuring a displacement of the mold wafer structure10on an XY plane and/or on a Z plane. The displacement sensor410may be fixed to the sensor arm420.

The sensor arm420may move in the XY plane above the mold wafer structure10. Further, the sensor arm420may move also in the Z plane.

Referring toFIG. 11, the sensor module400may deliver the warpage information to the controller200. The controller200may individually control each of the heaters131,133based on the warpage information.

As an example, the apparatus for reducing wafer warpage according to an exemplary embodiment of the present inventive concept may directly generate warpage information through the sensor module400, and may control the heaters131,133by using the warpage information.

A method for reducing wafer warpage according to an exemplary embodiment of the present inventive concept will be described in more detail below with reference toFIGS. 1 to 5 and 12 to 16. Elements or operations described with reference toFIGS. 1 to 5 and 12 to 16may be substantially the same as those described above and thus duplicative descriptions may be omitted.

FIG. 12is a flowchart illustrating a method for reducing wafer warpage according to an exemplary embodiment of the present inventive concept.FIGS. 13 to 16are views illustrating a method for reducing wafer warpage according to an exemplary embodiment of the present inventive concept.

Referring toFIG. 12, a chip structure may be formed on the wafer W (S100). The chip structure may be a stacked structure. The chip structure may include a plurality of chip structures, which may each be stacked structures.

As an example, referring toFIG. 13, first to sixth stack structures S1, S2, S3, S4, S5and S6may be formed on the wafer W; however, exemplary embodiments of the present inventive concept are not limited to a particular number of chip structures or a particular number of stack structures.

The stack structure S1may be a structure in which a plurality of chips. As an example, chips C1, C2, C3, C5and C5may be stacked. However, exemplary embodiments of the present inventive concept are not limited to a particular number of chips. The stack structure S1may include a plurality of chips C1-C5and a bonding material formed between each of adjacent chips of the plurality of chips C1-05.

The stack structure S1may be formed on the upper surface of the wafer W, and the bump B may be formed on the lower surface of the wafer W. The bump B may be electrically connected with each of the stack structures.

Referring again toFIG. 12, the mold layer M may be formed (S200).

As an example, referring toFIG. 14, the mold layer M may substantially surround the stack structure S1and may be formed on the wafer W. The mold layer M may be polymer such as an epoxy. However, exemplary embodiments of the present inventive concept are not limited thereto.

As the mold layer M is formed, the mold wafer structure10including the wafer W and the mold layer M may be formed.

Referring toFIGS. 15 and 16, for example, warpage of the wafer W may occur as the mold layer M is formed.

Referring toFIG. 15, warpage may occur along a length of the wafer W due to a difference in thermal expansion coefficients of the wafer W, the bonding material and the mold layer M. When the bump B faces upward and a bottom surface of the mold layer M faces downward, a center region of the mold wafer structure10may be relatively low and an edge region may be relatively high; however, exemplary embodiments of the present inventive concept are not limited thereto.

Referring toFIG. 16, warpage may occur along a length of the mold layer M due to a difference in thermal expansion coefficients of the wafer W, the bonding material and the mold layer M. When the bump B faces upward and a bottom surface of the mold layer M faces downward, a center region of the mold wafer structure10may be relatively high and an edge region may be relatively low; however, exemplary embodiments of the present inventive concept are not limited thereto.

Referring again toFIG. 12, the mold wafer structure10may be loaded on the stage100(S300). For example, the mold wafer structure10may be attached to the stage100.

As an example, referring toFIGS. 1 and 2, the stage100may fix the mold wafer structure10through at least one suction hole120.

As an example, referring toFIGS. 3 to 5, a portion to be heated may be different according to the warpage information. Thus, the warpage of the mold wafer structure10may be reduced or eliminated.

Referring again toFIG. 12, the chip structure may be tested (S500). For example, the stack structure S1may be tested.

When warpage occurs, as described herein, the chip structure might not be in a position for testing. Thus, warpage may be reduced or eliminated in the mold wafer structure (e.g., the mold wafer structure10) as described herein, and the chip structure (e.g., the stack structure S1) may be tested. Thus, warpage of the mold wafer structure may be reduced or eliminated, chip structures may be tested, and fabrication of a semiconductor device can be efficiently performed.

A method for reducing wafer warpage according to an exemplary embodiment of the present inventive concept will be described in more detail below with reference toFIGS. 12 and 17. Elements or operations described with reference toFIGS. 12 and 17may be substantially the same as those described above and thus duplicative descriptions may be omitted.

FIG. 17is a flowchart illustrating a method for reducing wafer warpage according to an exemplary embodiment of the present inventive concept.

Referring toFIG. 12, the chip structures may be formed on the wafer (S100), the mold layer may be formed (S200), the mold wafer structure may be loaded on the stage (S300), and the mold wafer structure may be heated (S400). The chip structure (e.g., the stack structure S1) may be tested thereafter.

Referring toFIG. 17, heating the mold wafer structure10(e.g., step S400) may include following processes.

First, warpage information may be acquired (S410).

The acquired warpage information may be previously measured information. Alternatively, the warpage information may be newly measured and acquired with the method for reducing wafer warpage according to an exemplary embodiment of the present inventive concept.

The mold wafer structure may be heated based on the warpage information (S420). For example, the mold wafer structure10may be heated based on the warpage information.

The on or off state of the heaters according to an exemplary embodiment of the present invention, and temperatures thereof may be individually controlled according to the warpage information. Thus, relatively fine control of the heaters may be performed based on the warpage information.

Referring again toFIG. 12, the stack structure (e.g., S1) may be tested (S500).

A method for reducing wafer warpage according to an exemplary embodiment of the present inventive concept will be described in more detail below with reference toFIGS. 18 and 19. Elements or operations described with reference toFIGS. 18 and 19may be substantially the same as those described above and thus duplicative descriptions may be omitted.

FIG. 18is a flowchart illustrating a method for reducing wafer warpage according to an exemplary embodiment of the present inventive concept.FIG. 19is a view illustrating the method for reducing wafer warpage ofFIG. 18.

Referring toFIG. 18, the chip structures may be formed on the wafer (S100), and the mold layer may be formed (S200).

The mold wafer structure may be loaded on a loading stage (S310). For example, the mold wafer structure may be attached to the loading state.

As an example, referring toFIG. 19, a loading stage500may be a stage for transferring a mold wafer structure10a.

Referring toFIG. 18, the mold wafer structure may be heated (S320).

As an example, the mold wafer structure10amay be heated on the loading stage500. Thus, the warpage of the mold wafer structure10amay be reduced or eliminated.

The mold wafer structure may be loaded on a test stage (S330). As an example, the mold wafer structure may be attached to the test stage.

As an example, referring toFIG. 19, the test stage100illustrated inFIG. 19may be the same as the stage100described above. A mold wafer structure10bmay be previously heated on the loading stage500, and the warpage may be of the mold wafer structure10bmay be eliminated. Thus, a test of a stack structure (e.g., S1) may be substantially immediately performed on the test stage100.

The method for reducing wafer warpage according to an exemplary embodiment of the present inventive concept may include substantially immediately performing a chip structure (e.g., stack structure S1) test without an additional warpage reducing process on the test stage100because the warpage may be reduced or eliminated during the time of transferring the mold wafer structure (e.g.,10a). Thus, process efficiency can be increased and costs can be reduced or eliminated.