JP2013254905A - Probing stage for semiconductor wafer, semiconductor inspection device, and method of determining stage groove width - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a probing stage for a semiconductor wafer capable of reducing damage to a wafer caused by a probe, a semiconductor inspection device equipped with the stage, and a method of determining a stage groove width.SOLUTION: The probing stage for semiconductor wafer is so constituted that a mounting surface 2 of a stage 10 that mounts, sucks, and holds a thin film semiconductor wafer 70 is formed with a plurality of grooves 3 connected to a sucking device 20, and a groove width of each groove 3 is such a width as to shear-destroy the thin film semiconductor wafer by a shear span ratio.

Description

  The present invention relates to a semiconductor wafer probing stage on which a semiconductor wafer is placed when inspecting the semiconductor wafer, a semiconductor inspection apparatus including the probing stage, and a method for determining a width of a groove formed on the probing stage.

  2. Description of the Related Art A semiconductor inspection apparatus that inspects electrical characteristics of a plurality of chips formed on a semiconductor wafer using a test jig such as a needle-like probe is known. In such a semiconductor inspection apparatus, the electrical characteristics of each chip are inspected by bringing a chip formed on the wafer into contact with a probe fixed above the stage on which the semiconductor wafer is placed. At this time, the stage on which the semiconductor wafer is placed is moved by the arm, and a plurality of chips are inspected by changing the contact position of the probe. In addition, if the wafer position is shifted on the stage during the inspection process, an accurate inspection cannot be performed. Therefore, it is necessary to hold the wafer at a predetermined position on the stage. Therefore, a plurality of grooves are formed on the wafer mounting surface of the stage, and the wafer is sucked and fixed to the stage by sucking air in the grooves.

On the other hand, in recent years, semiconductor wafers have been made thinner. Thin wafers have a lower strength than conventional wafers due to their reduced thickness. As described above, the probe is pressed against the wafer in the electrical characteristic inspection on the wafer chip. Here, when the pressing position of the probe overlaps with the position of the groove, since the lower portion of the wafer becomes a cavity, the thin wafer may be broken by the pressing load by the probe.
For example, techniques disclosed in Patent Literature 1 and Patent Literature 2 are known as conventional techniques for suppressing the destruction of the wafer on the groove.

JP 2008-294373 A JP 2010-103238 A

In Patent Document 1, a plurality of grooves are formed on the wafer mounting surface of the stage, and the width of the plurality of grooves is set to be twice or less of the wafer thickness, so that even when the probe presses the wafer on the grooves, the wafer It is disclosed that the local bending rigidity of can be improved.
However, Patent Document 1 does not clearly describe the technical significance that the destruction of the wafer can be suppressed by setting the groove width to be equal to or less than twice the thickness of the wafer. Therefore, for example, when the thickness of the wafer is 50 μm, the groove width is 100 μm or less. However, this groove width is too narrow to attract the wafer, and is not a realistic groove width. Therefore, the invention of Patent Document 1 has a problem that the wafer cannot be held on the inspection stage.

  Further, in the semiconductor inspection apparatus of Patent Document 2, a wafer support member that can move in the height direction of the groove in a groove formed on the wafer placement surface of the stage, and an upper surface of the wafer support member from the placement surface. A moving mechanism is provided for moving the wafer support member from the retracted first position to a second position where the upper surface of the wafer support member is flush with the mounting surface. This semiconductor inspection apparatus is characterized in that when the moving mechanism moves at least one of the plurality of wafer support members to the second position, the remaining wafer support members are in the first position. Due to this feature, when the probe position overlaps with the groove, the support member in the groove supports the wafer to suppress the breakage of the wafer.

  However, the invention of Patent Document 2 has a problem that the driving mechanism of the stage on which the wafer is placed becomes complicated, leading to an increase in the cost of the apparatus. In addition, since the wafer support member is not disposed under the suction hole for sucking air in the groove disposed on the wafer mounting surface, the probe presses the wafer at the position on the suction hole. In some cases, the wafer may be destroyed.

  The present invention has been made in order to solve such problems. A semiconductor wafer probing stage, a semiconductor inspection apparatus including the probing stage, and the above-described probing stage, which can reduce wafer breakage by a probe as compared with the prior art. An object of the present invention is to provide a method for determining a groove width in a probing stage.

In order to achieve the above object, the present invention is configured as follows.
That is, the probing stage for a semiconductor wafer according to one aspect of the present invention has a mounting surface on which a thin semiconductor wafer is mounted, and a plurality of grooves for sucking and holding the semiconductor wafer on the mounting surface. The width of each groove is characterized in that the shear span ratio, which is the ratio of the groove width to the thickness of the thin semiconductor wafer, is set to a groove width that causes shear failure.

  According to the probing stage for a semiconductor wafer in one aspect of the present invention, the groove width of the groove formed on the stage is set to a groove width that causes a thin semiconductor wafer to undergo shear fracture. As a result, even when the wafer is probed at a position on the thin wafer corresponding to the groove, there is a margin between the pressing load until the thin wafer breaks and the actual probing load. Therefore, it is possible to suppress the destruction of the thin wafer during probing. Even if the thin wafer breaks, shear fracture occurs, so the breakage occurs only directly under the probe and does not propagate on the thin wafer. Therefore, the destruction of the thin wafer can be minimized. As a result, productivity of a thin semiconductor wafer can be improved.

It is a top view of the probing stage with which the semiconductor inspection apparatus in the embodiment of the present invention is equipped. It is sectional drawing in the AA part of the probing stage shown in FIG. It is an expanded sectional view of the groove part shown in FIG. It is the figure which showed the relationship of the load until a thin wafer reaches destruction with respect to a shear span ratio. 2 is a flowchart for explaining a method of determining a groove width of the probing stage shown in FIG. 1 according to the embodiment of the present invention.

  A semiconductor wafer probing stage according to an embodiment of the present invention, a semiconductor inspection apparatus including the probing stage, and a method for determining a groove width in the probing stage will be described below with reference to the drawings. In each figure, the same or similar components are denoted by the same reference numerals.

  The semiconductor wafer probing stage of this embodiment, which will be described in detail below, is a stage on which a semiconductor wafer is placed when the electrical characteristics of chips formed on the semiconductor wafer are contact-inspected with a probe. A groove for wafer adsorption is formed on the surface. Such a probing stage of the present embodiment has an optimum groove width particularly for a thin semiconductor wafer. Here, the thin thickness corresponds to a thickness of, for example, 10 to 200 μm, and is thinner than a conventional thickness of, for example, 200 to 400 μm.

In addition, this embodiment pays attention to the fact that there are two modes in the mode in which the thin wafer is destroyed by pressing the probe on the position on the thin wafer corresponding to the groove of the stage. The groove width of the stage is determined based on the difference.
That is, one of the above two modes is a bending failure in which the thin wafer breakage propagates from the starting point onto the wafer surface, and the other is the punching shape directly under the probe without the thin wafer breakage propagation. It is the destruction by the shear which becomes destruction of. Which of these two destruction modes corresponds is determined by the shear span ratio, which is the ratio between the wafer suction groove width and the wafer thickness. In addition, when the probe is pressed against the thin wafer on the groove, the load until the wafer is broken differs corresponding to each destruction mode. That is, in the shear fracture, the probing load (the load that the thin wafer receives from the probe) until the thin wafer breaks is larger than the bending fracture.
Assuming these contents, the width of the groove formed in the probing stage for semiconductor wafers of this embodiment is such that when the probe is pushed in until the thin wafer on the groove breaks, the fracture shape of the thin wafer is shear fracture. Is set to the groove width.
More specific description will be given below.

Embodiment 1 FIG.
1 and 2 show a semiconductor inspection apparatus 101 including the above-described semiconductor wafer probing stage 10, suction apparatus 20, inspection apparatus 30, and stage moving apparatus 40 of the present embodiment.
The probing stage 10 has, for example, a circular planar shape, and has a placement surface 2 on which a thin wafer 70 (FIG. 2) is placed. A plurality of grooves 3 are formed concentrically, for example, on the mounting surface 2, and suction holes 4 for sucking air in the grooves are formed in each groove 3. In the present embodiment, the distance between the adjacent grooves 3 in the diametrical direction of the probing stage 10 is set at an equal pitch. Further, as described above, the groove width 3a (FIG. 3) of the groove 3 in the diameter direction is set to a groove width at which the fracture shape of the thin wafer 70 causes shear fracture. This will be described in more detail below.

  The suction hole 4 formed in each groove 3 communicates with a pipe 5 formed in the probing stage 10, and the pipe 5 is connected to the suction device 20. The adsorption device 20 is, for example, a device that includes a vacuum pump or the like and sucks air in the groove 3 and the tube 5 portion. Therefore, the probing stage 10 sucks and holds the thin wafer 70 placed on the placement surface 2 when the air in the groove 3 is sucked by the suction device 20. In addition, the shape of the groove | channel 3 is not limited to the pattern shown in FIG. 1, and the cross-sectional shape shown in FIG.

  The inspection device 30 includes a probe 31 and inspects the electrical characteristics of the chip by pressing the probe 31 against an electrode in a chip region formed on the thin wafer 70. In the present embodiment, the probe 31 has a fixed configuration.

  The stage moving device 40 includes a mechanism having an arm connected to the probing stage 10, and the thin wafer 70 is brought to a predetermined inspection position where the probe 31 is brought into contact when the inspection device 30 performs an electrical characteristic inspection of the thin wafer 70. The probing stage 10 is moved by driving the arm so as to be disposed. In this embodiment, the probing stage 10 is moved with respect to the probe 31. In short, a moving device that moves the probe 31 and the probing stage 10 relatively may be configured.

Next, a method for determining the width 3a of the groove 3 will be described in more detail.
As already described, the groove width 3a is determined by the shear span ratio (ratio between the groove width 3a and the thickness of the thin wafer 70). Hereinafter, the shear span ratio will be described.
FIG. 4 is a diagram showing the relationship between the load at which the thin wafer 70 breaks and the break mode (break shape) with respect to the shear span ratio. As shown in FIG. 4, the load until the thin wafer 70 breaks and the break mode of the thin wafer 70 differ depending on the shear span ratio.
That is, when the thickness of the thin wafer 70 is the same, when the shear span ratio is smaller than 10, that is, when the groove width 3a is relatively narrow, the probing load until the thin wafer 70 breaks is relatively large. On the other hand, when the shear span ratio is larger than 10, that is, when the groove width 3a is wide, the probing load until the thin wafer 70 breaks is relatively small.

  Further, the destruction mode of the thin wafer 70 is switched depending on the shear span ratio. In other words, when the shear span ratio is relatively small, the thin wafer 70 undergoes shear failure, whereas when the shear span ratio is large, it results in bending failure.

  In order to confirm the destruction mode of the thin wafer 70 at the position on the thin wafer 70 corresponding to the groove 3, the probe 31 is pressed against the thin wafer 70 from above the groove 3 until the thin wafer 70 breaks. It is necessary to confirm the fracture shape of the thin wafer 70. At this time, when the fracture shape of the thin wafer 70 remains only directly below the probe 31, the fracture mode is shear fracture. On the other hand, when the fracture propagates through the thin wafer 70 using the point at which the fracture of the thin wafer 70 is pressed against the probe 31, the fracture mode is bending fracture.

Based on these points, the procedure of the method for determining the groove width 3a will be described with reference to the flowchart of the method for determining the groove width shown in FIG.
First, in step S1 and step S2, an arbitrary groove width corresponding to the design width is provisionally determined, and a stage in which a design groove having the provisionally determined groove width is formed is prepared.
Next, in step S3 and step S4, the thin wafer 70 is placed and adsorbed on the stage where the design groove is formed, and then the probe 31 is placed at a position on the thin wafer 70 corresponding to the groove of the stage. Deploy.

  In the next step S5, the thin wafer 70 and the probe 31 are relatively moved in the thickness direction of the thin wafer 70 until the thin wafer 70 is broken. For example, the probe is pushed in from the upper part of the thin wafer 70 until the thin wafer 70 is broken.

  In the next step S6, it is determined whether or not the fracture shape in the thin wafer 70 corresponds to a shear fracture shape. This determination is performed, for example, by an operator with a microscope.

  If the result of this determination is that the fracture mode is bending fracture, that is, a fracture mode in which fracture has propagated, the process proceeds to step S7, where a design groove having a groove width narrower than the provisionally determined design width is selected. A second stage is prepared. Then, the above-described steps S3 to S6 are repeated again until the fracture mode becomes a shear fracture, that is, a fracture mode in which punching fracture occurs.

  Then, the design width at the time when the fracture mode becomes shear fracture (step S8) is set to the groove width 3a.

  In this way, it is possible to determine the groove width 3a that can suppress the destruction of the thin wafer 70 when the thin wafer 70 on the groove 3 is probed.

  On the other hand, since the shear span ratio resulting in shear failure varies depending on the thickness and structure of the thin wafer 70, it is necessary to obtain the groove width 3 a that causes shear failure for each thin wafer 70. For example, when the main material of the thin wafer 70 is silicon and the wafer thickness is 50 μm, when the groove width 3 a is determined so that the shear span ratio is “4”, the failure mode of the thin wafer 70 is shear failure. . On the other hand, if the groove width 3a is too narrow, the thin wafer 70 cannot be sucked and fixed because the suction force for fixing the thin wafer 70 to the probing stage 10 is insufficient. Therefore, after determining the groove width 3a by the above-described groove width determination method in the present embodiment, it is necessary to increase the number of the grooves 3 according to the groove width 3a. In this way, the probing stage 10 for the thin wafer 70 is designed.

As described above, by selecting the groove width 3a in which the failure mode of the thin wafer 70 is the shear failure, between the pressing load until the thin wafer 70 breaks and the probing load actually used at the time of inspection. In this case, even if the thin wafer 70 is destroyed by probing, the destruction of the thin wafer 70 does not propagate from the probing location to other locations, so that the destruction of the thin wafer 70 is minimized. Can do.
As described above, by using the semiconductor wafer probing stage according to the present embodiment, the semiconductor inspection apparatus including the stage, and the method for determining the groove width of the stage, damage to the thin wafer 70 is reduced as compared with the conventional technique. Thus, the yield of the thin wafer 70 can be improved, that is, the productivity can be improved.

  Further, according to the probing stage for a semiconductor wafer and the semiconductor inspection apparatus provided with this stage according to the present embodiment, it is not necessary to provide a complicated mechanism in the groove as disclosed in Patent Document 2. Therefore, the cost can be significantly reduced as compared with the apparatus disclosed in Patent Document 2.

2 mounting surface, 3 grooves, 3a groove width, 10 probing stage,
20 adsorption device, 30 inspection device,
101 Semiconductor inspection apparatus.

Claims (4)

In a probing stage for a semiconductor wafer having a mounting surface on which a thin semiconductor wafer is mounted, and on the mounting surface, a plurality of grooves for adsorbing and holding the semiconductor wafer are formed.
A width of each groove is set to a groove width at which a shear span ratio, which is a ratio of the groove width to the thickness of a thin semiconductor wafer, causes shear failure. A probing stage for a semiconductor wafer according to claim 1;
A suction device that is connected to each of the grooves, sucks air in each groove, and sucks and holds the semiconductor wafer on the placement surface;
An inspection device that contacts the semiconductor wafer sucked and held on the probing stage and inspects its electrical characteristics;
A semiconductor inspection apparatus comprising: A method of determining a groove width of a plurality of grooves formed on a mounting surface of a stage on which a thin semiconductor wafer is mounted and holding the semiconductor wafer on the mounting surface.
A groove width determination method, wherein the width of each groove is set to a groove width at which a shear span ratio, which is a ratio between the groove width and the thickness of a thin semiconductor wafer, causes shear failure. A thin semiconductor wafer is sucked and held by the design groove on the stage where the design groove having the design width is formed,
At the position on the semiconductor wafer corresponding to the design groove, press the semiconductor wafer until the semiconductor wafer is broken,
Determine whether the fracture shape in the semiconductor wafer is a shear fracture shape,
Until the fracture shape becomes a shear fracture shape, the destruction of the semiconductor wafer is repeated at the stage of the design groove formed with the narrower design width.
The groove width determination method according to claim 3, wherein the groove width is determined such that the fracture shape becomes a shear fracture shape.

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