JP2021111675A - Method of bonding semiconductor chip and support substrate, method of polishing semiconductor chip, and method of bonding wafer and support substrate - Google Patents

Abstract

To bond a semiconductor chip or a wafer to a support substrate in a parallel state.SOLUTION: A method of bonding a semiconductor chip includes: a first step of bonding a support substrate 20 made of a first permanent magnet and a semiconductor chip 10 with wax 31 to prepare a first attachment 102; a second step of creating an adsorbent 40 by adsorbing the first attachment 102 and a second permanent magnet 25; a third step SP4 of heating the adsorbent 40 to equal to or higher than the melting point of the wax 31; a fourth step SP5 of cooling the adsorbent 40 heated in the third step SP4; and a fifth step SP6 of separating the second permanent magnet 25 from the adsorbent 40 cooled in the fourth step SP5 to prepare a second attachment 100 in which the semiconductor chip 10 and the support substrate 20 are bonded together.SELECTED DRAWING: Figure 2

Description

The present invention relates to a method of bonding a semiconductor chip or wafer to a support substrate, and is used, for example, in a pre-process of polishing a semiconductor chip having multiple layers of wiring to expose a specific wiring layer.

When inspecting a semiconductor chip, the semiconductor chip package may be polished to expose the metal wiring layer. Further, in the semiconductor chip, a metal wiring layer and an interlayer insulating layer are laminated in multiple layers. The semiconductor chip may be polished to a specific wiring layer to inspect and analyze the exposed metal wiring layer. In the polishing step, the polishing apparatus grips the support substrate to which the semiconductor chips are bonded with wax.

Patent Document 1 describes a technique of adhering a semiconductor wafer and a support plate with an adhesive containing a heat-dissipating resin, and then heating and peeling them off.

JP-A-2004-186263 (Claim 1, paragraphs 0030, 0031)

When polishing a semiconductor chip, it is necessary to make the semiconductor chip and the support substrate parallel to each other. By the way, wax has a higher melting point than room temperature and has a high viscosity temperature dependence. Therefore, it is necessary to repeat the heating step, the step of finely adjusting the inclination, and the cooling step to gradually make the semiconductor chips parallel. Since such work is cumbersome and time-consuming, it is preferable to bond them in a parallel state.

The present invention has been made in view of such circumstances, and an object of the present invention is to provide a bonding method capable of bonding a semiconductor chip or a wafer in a parallel state to a support substrate, and a semiconductor chip polishing method. ..

In order to achieve the above object, the method of bonding the semiconductor chip and the support substrate of the present invention is a first method in which a support substrate made of a ferromagnet (for example, a permanent magnet or an iron plate) and a semiconductor chip are bonded with wax. The first step of creating a sticker, the second step of creating an adsorbent by adsorbing an opposing member (for example, a permanent magnet, a magnet sheet) made of a ferromagnetic material and the first affix, and the adsorbent. The facing member is separated from the third step of heating the magnet to a temperature equal to or higher than the melting point of the wax, the fourth step of cooling the adsorbent heated in the third step, and the adsorbent cooled in the fourth step. A fifth step of producing a second attachment in which the semiconductor chip and the support substrate are bonded is provided, and at least one of the support substrate and the facing member is magnetized.

According to the present invention, a semiconductor chip or wafer can be attached to a support substrate in a parallel state.

It is explanatory drawing (1) explaining the method of bonding the semiconductor chip and the support substrate which are 1st Embodiment of this invention. It is explanatory drawing (2) explaining the method of bonding the semiconductor chip and the support substrate which are 1st Embodiment of this invention. It is explanatory drawing explaining the process of polishing to a predetermined wiring layer. It is explanatory drawing explaining the bonding method of the semiconductor chip and the support substrate which is the 1st comparative example of this invention. It is a figure which shows the measurement point of the thickness of a permanent magnet, a quartz substrate, and a silicon wafer. It is explanatory drawing explaining the bonding method of the semiconductor chip and the support substrate which are 2nd Embodiment of this invention. It is explanatory drawing explaining the bonding method of the semiconductor chip and the support substrate which is the 2nd comparative example of this invention. It is explanatory drawing explaining the double-sided magnetized magnet sheet used in the bonding method of the semiconductor chip and the support substrate which are 3rd Embodiment of this invention. It is explanatory drawing explaining the magnet sheet used in the method of bonding a semiconductor chip and a support substrate which are 4th Embodiment of this invention. It is explanatory drawing explaining the bonding method of the semiconductor chip and the support substrate which are 5th Embodiment of this invention.

Hereinafter, embodiments of the present invention (hereinafter, referred to as “the present embodiment”) will be described in detail with reference to the drawings. In addition, each figure is only shown schematicly to the extent that the present embodiment can be fully understood. Further, in each figure, common components and similar components are designated by the same reference numerals, and duplicate description thereof will be omitted.

(First Embodiment)
FIGS. 1 and 2 are explanatory views illustrating a method of bonding the semiconductor chip and the support substrate according to the first embodiment of the present invention.
The semiconductor chip 10 is, for example, a Si substrate 15 (see FIG. 3) formed with an electric circuit (not shown). A semiconductor wafer may be used instead of the semiconductor chip 10. The support substrate 20 is a permanent magnet magnetized with a ferromagnet of a circular flat plate. One surface of this permanent magnet is magnetized to the south pole, and the other surface is magnetized to the north pole. The wax 30 is solid at room temperature and dissolves and liquefies at a predetermined melting point (about 70 ° C.).
The attachment 100 (SP6 in FIG. 2) in which the semiconductor chip 10 and the support substrate 20 are bonded together with wax 30 is produced through the following steps (steps).

First, the operator applies the wax 30 to the central portion of the support substrate 20. At this time, the wax 30 does not need to be applied uniformly. After applying the wax 30, the operator places the semiconductor chip 10 on the support substrate 20 to which the wax 30 is applied (step SP1). As a result, the support substrate 20 and the semiconductor chip 10 are bonded together with the wax 30, and a patch 101 (step SP2) is created. At this time, the polarity of the support substrate 20 on the side on which the semiconductor chip 10 is placed is set to N pole, but S pole may be used.

After step SP1, the operator causes the support substrate 20 on which the semiconductor chip 10 is placed and the facing member 25 to face each other on the table 50 and attract them to each other (step SP2). The opposing member 25 is a permanent magnet magnetized with a ferromagnet. The support substrate 20 and the facing member 25 have different magnetic poles facing each other. If the opposing member 25 is a permanent magnet, the support substrate 20 may be a simple iron plate that is not magnetized, even if it is not a permanent magnet. As a result, the adsorbent 40 between the support substrate 20 and the facing member 25 is created by inserting the semiconductor chip 10 (step SP3).

After step SP3, the operator heats the adsorbent 40 above the melting point of the wax 30 (SP4 in FIG. 2). The wax 30 melted by heating is referred to as molten wax 31. The thickness of the molten wax 31 is made uniform by the adsorption force (magnetic force) that attracts the support substrate 20 and the facing member 25. That is, the semiconductor chip 10 receives buoyancy and surface tension on the molten wax 31 having a uniform thickness. The one in which the molten wax 31 is inserted between the support substrate 20 and the semiconductor chip 10 is referred to as a patch 102.

After step SP4, the operator cools the adsorbent 40 to room temperature (step SP5). As a result, the molten wax 31 inserted between the semiconductor chip 10 and the support substrate 20 solidifies in a uniform thickness. This solidified wax is referred to as wax 32, and the cooled adsorbent 40 is referred to as adsorbent 41.

After step SP5, the operator pulls the support substrate 20 to which the semiconductor chip 10 is attached and the facing member 25 apart (step SP6). As a result, a patch 100 is created in which the semiconductor chip 10 and the support substrate 20 are bonded together with a wax 32 having a uniform thickness.

FIG. 3 is a structural diagram showing a part of the semiconductor chip.
The semiconductor chip 10 is, for example, formed with an electric circuit (not shown) formed on a Si substrate 15, and has a plurality of wiring layers 12a, 12b, 12c, 12d, and 12e formed in multiple layers. Further, between the wiring layers 12a, 12b, 12c, 12d and the adjacent wiring layers 12b, 12c, 12d, 12e, interlayer insulating layers 13b, 13c, 13d, 13e such as _{SiO 2 and SiN are formed.} .. An interlayer insulating layer 13a is formed on the outermost surface. The interlayer insulating layers 13a, 13b, 13c, 13d, and 13e are collectively referred to as an insulating layer 14.

A broken line is drawn at the boundary between the wiring layer 12d and the interlayer insulating layer 13d. After step SP6 (FIG. 2), the operator fixes, for example, the support substrate 20 of the attachment 100 (SP6 in FIG. 2) to a polishing device (not shown) and polishes the semiconductor chip 10 up to this broken line. .. Thereby, the shape inspection and analysis of the specific wiring layer 12d can be performed. Here, the determination of whether or not the polishing is performed up to the specific wiring layer 12d is determined by, for example, the change in the polishing rate occurring at the boundary between the wiring layers 12a, 12b, 13c, 13d and the interlayer insulating layers 13a, 13b, 13c, 13d. Counting is performed based on the change in polishing rate that occurs at the boundary between the interlayer insulating layer 13d and the wiring layer 12d.

(First comparative example)
FIG. 4 is an explanatory diagram illustrating a method of bonding the semiconductor chip and the support substrate, which is the first comparative example of the present invention.
The support substrate 20 uses a quartz substrate instead of a permanent magnet. Further, as the facing member, a weight 70 is used instead of the permanent magnet 25 (FIG. 1). First, the operator applies the wax 30 to the support substrate 20 placed on the table 50 in the same manner as in step SP1 (FIG. 1) of the first embodiment. After coating, the operator places the semiconductor chip 10 on the quartz substrate 20 coated with the wax 30. Further, the operator places the weight 70 on the semiconductor chip 10. Then, in the same manner as in the above embodiment, heating and cooling are performed, and the weight 70 is removed. As a result, the attachment 110 in which the semiconductor chip 10 and the support substrate 20 are bonded with wax 30 is produced.

A silicon wafer of 4 inchφ was used instead of the semiconductor chip 10. That is, in the first embodiment, a silicon wafer is bonded to a permanent magnet as the support substrate 20. Further, in the first comparative example, a silicon wafer is bonded to a quartz substrate as a support substrate 20.

FIG. 5 is a diagram showing measurement points of thicknesses of permanent magnets, quartz substrates, and silicon wafers.
Prior to pasting, the thickness of the first permanent magnet as the support substrate 20, the second permanent magnet as the opposing member 25, the quartz substrate as the support substrate 20, and the silicon wafer was adjusted to the central portion A and the peripheral portions at four locations. Measure at a total of 5 points (B, C, D, E).

Next, wax was applied and the silicon wafer was attached to the first permanent magnet (SP1 (FIG. 1)), and the adsorbent adsorbed by the second permanent magnet was heated (SP4). The set temperature of the hot plate at this time is 170 ° C., the surface temperature of the first permanent magnet is 75 ° C. to 80 ° C., and the heating time is 15 minutes.

Next, after cooling (SP5), the thickness of the attachment from which the second permanent magnet was pulled away was measured at five points, and the thickness of (wafer + wax) and the thickness of wax were calculated. Similarly, as a first comparative example, the thickness of the pasted material in which the silicon wafer and the quartz substrate were bonded was measured at five points, and the thickness of (wafer + wax) and the thickness of wax were calculated. Table 1 shows these measured and calculated values.

In the central portion A, the thickness of the wax of Example 1 was 1 [μm], while the thickness of the wax of the first comparative example was 18 [μm]. Further, in the peripheral portions B, C, D, and E, the thickness of the wax of Example 1 was 2 to 3 [μm], while the thickness of the wax of the first comparative example was 2 to 6 [μm]. In Example 1 in which the two permanent magnets are attracted, the thicknesses of the peripheral portions B, C, D, and E are more uniform than those in the comparative example. Further, in particular, in Example 1, the thickness of the central portion A is extremely reduced, and the wax is uniformly applied.

As described above, in the pasted object 110 created by the laminating method according to the first comparative example, the central portion A is thicker than the peripheral portions B, C, D, and E. In this case, even if the semiconductor chip 10 is polished, only a part of the specific wiring layer is exposed, and the entire specific wiring layer cannot be exposed.

However, in the bonding method of the first embodiment, the magnetic force makes the thickness of the support substrate 20 and the facing member 25 uniform. Therefore, when the semiconductor chip 10 is polished by a polishing device (not shown), the entire specific wiring layer is exposed. Further, in the bonding method of the first embodiment, the weight 70 is not used as in the bonding method according to this comparative example.

(Second Embodiment)
In the first embodiment, the table 50 is arranged horizontally, but in the second embodiment, the table 50 is tilted, and the semiconductor chip 10 and the support substrate 20 are bonded together with wax 30 in a tilted state.

FIG. 6 is an explanatory diagram illustrating a method of bonding the semiconductor chip and the support substrate according to the second embodiment of the present invention.
The table 50 is tilted by an angle θ with respect to the horizontal plane. Similar to SP3 (FIG. 1) of the first embodiment, the adsorbent 42 is prepared on the inclined table 50. The adsorbent 42 is formed by inserting a semiconductor chip 10 between a permanent magnet as a support substrate 20 and a permanent magnet as an opposing member 25. At this time, the adsorbent 42 is heated and cooled in an inclined state. Then, the opposing member 25 is peeled off from the adsorbent 42 to create the attachment 103.

(Second comparative example)
FIG. 7 is an explanatory diagram illustrating a method of bonding the semiconductor chip and the support substrate, which is the second comparative example of the present invention.
Similar to the first comparative example, the operator creates the adsorbent 43 on the inclined table 50. The adsorbent 43 is formed by inserting a semiconductor chip 10 between a quartz substrate as a support substrate 20 and a weight 70. At this time, the operator heats and cools the adsorbent 43 in an inclined state. Then, the weight 70 is removed from the adsorbent 43 to create the attachment 104.

The inclination angle θ of the table 50 is θ = 30 degrees. Further, the E side in FIG. 5 is high and the D side is low. Other conditions are the same as in Example 1.

The thickness of the wax when the quartz substrate was used was 8 [μm] at the position where the height of inclination was high (point E) and 2 [μm] at the position where the height was low (point D). .. Further, the thickness of the wax when the permanent magnet is used is 4 [μm] at the position where the height of inclination is high (point E) and 1 [μm] at the position where the height is low (point D). there were. That is, in both the quartz substrate and the permanent magnet, the thickness of the peripheral portion changes depending on the inclination. Further, when a permanent magnet is used, the thickness of the wax is thinner and more uniform than when a quartz substrate is used.

Further, even when the quartz substrate is tilted, the wax in the central portion (point A) has a thickness of 12 [μm] when a quartz substrate is used, but by using a permanent magnet, the wax has a thickness of 2 [μm]. It has become thin and uniform.

(Third Embodiment)
In the first embodiment, the support substrate 20 which is a permanent magnet and the facing member 25 which is a permanent magnet are attracted to each other, but the support substrate 20 which is a permanent magnet and the magnet sheet can also be attracted to each other.

In the bonding method of the present embodiment, a magnet sheet (FIG. 8) magnetized on both sides is used as the opposing member 25 of the first embodiment instead of the permanent magnet. A magnet sheet magnetized on both sides is a magnet in which an N pole is magnetized on one of the front and back surfaces of the sheet and an S pole is magnetized on the other surface. That is, in the bonding method of the present embodiment, the wax 30 is applied to the permanent magnet (support substrate 20) placed on the table 50 in the same manner as the SP1 (FIG. 1) of the first embodiment. After coating, the operator places the semiconductor chip 10 on the support substrate 20 coated with the wax 30.

Further, the operator attracts the magnet sheet magnetized on both sides and the support substrate 20 with the semiconductor chip 10 interposed therebetween. By heating this adsorbed material, the permanent magnet (support substrate 20) and the magnet sheet are attracted in parallel. Therefore, the support substrate 20 and the semiconductor chip 10 are attached in parallel.

(Fourth Embodiment)
The support substrate 20 used in the bonding method of the second embodiment was a permanent magnet. As the support substrate 20, a simple unmagnetized iron plate may be used instead of the permanent magnet. According to this, not only a magnet sheet magnetized on both sides but also a magnet sheet magnetized on one side and multipoles on both sides can be used.

FIG. 9 is an explanatory view of a magnet sheet used in the method of bonding a semiconductor chip and a support substrate according to a third embodiment of the present invention. FIG. 9A is a single-sided multi-pole magnetized magnet sheet, and FIG. 9B is a double-sided multi-pole magnetized magnet sheet.

The single-sided multi-pole magnetized magnet sheet (FIG. 9A) is a magnet in which N poles and S poles are alternately magnetized only on one side of the sheet, and attracts only the magnetized side surface. The double-sided multi-pole magnetized magnet sheet (FIG. 9B) is a magnet in which N poles and S poles are alternately magnetized on both sides of the sheet, and both sides can be attracted to each other.

That is, in the bonding method of the present embodiment, the wax 30 is applied to the iron plate (support substrate 20) placed on the table 50 in the same manner as SP1 (FIG. 1) of the first embodiment. After coating, the operator places the semiconductor chip 10 on the support substrate 20 coated with the wax 30.

Further, the operator attracts the magnet sheet that is multi-pole magnetized on one side or multi-pole magnetized on both sides and the support substrate 20 with the semiconductor chip 10 interposed therebetween. By heating this adsorbent, the support substrate 20 and the semiconductor chip 10 are attached with a uniform thickness.

(Fifth Embodiment)
In the bonding method of the first embodiment, the support substrate 20 which is a permanent magnet and the facing member 25 which is a permanent magnet are attracted to each other, but the thickness of the supporting substrate 20 and the facing member 25 is made uniform by the repulsive force. can do.

FIG. 10 is an explanatory diagram illustrating a method of attaching the semiconductor chip and the support substrate according to the fifth embodiment of the present invention.
The sticking method of the present embodiment includes a step of accommodating two sets of sticking materials 101, in which the semiconductor chip 10 and the support substrate 20 are bonded with wax 30, inside the cylindrical cylinder 60. The tubular body 60 is a container in which two containers having a circular shape in cross section are integrated by tightening screws or the like. The support substrate 20 is a disk-shaped permanent magnet as in the first embodiment. In this embodiment, the opposing member 25 used in the first embodiment is not used.

The two support substrates housed in the cylinder 60 have the same poles facing each other and repel each other. Therefore, the surface 10a of the semiconductor chip 10 is pressed against the bottom surface 60a of the tubular body 60.

By heating the tubular body 60 containing the two sets of patches 101 and 101, the wax 30 is melted and the thickness of the semiconductor chip 10 and the support substrate 20 is made uniform. Further, the molten wax 31 having a uniform thickness is formed. By cooling after heating, the molten wax 31 is solidified, and the semiconductor chip 10 and the support substrate 20 are bonded in parallel with the wax 32 having a uniform thickness.

As described above, according to the bonding method of the present embodiment, two sets of patches 100 in which the surface of the semiconductor chip 10 and the support substrate 20 are uniformly bonded are simultaneously produced by heating and cooling.

10 Semiconductor chip (object to be polished)
20 Support substrate (permanent magnet)
25 Opposing members (permanent magnet, iron plate, magnet sheet)
30, 32 Wax 31 Molten wax 40, 41, 42, 45 Adsorbent 50 Table 60 Cylinder 70 Weight 100, 101, 102, 105, 110 Attached material (bonded material)

Claims (6)

The first step of creating a first patch in which a support substrate made of a ferromagnet and a semiconductor chip are bonded with wax, and
The second step of creating an adsorbent in which the opposing member made of a ferromagnet and the first affix are adsorbed, and
A third step of heating the adsorbent above the melting point of the wax, and
The fourth step of cooling the adsorbent heated in the third step and
The present invention includes a fifth step of pulling the opposing member away from the adsorbent cooled in the fourth step to prepare a second sticker in which the semiconductor chip and the support substrate are bonded together.
A method of bonding a semiconductor chip and a support substrate, characterized in that at least one of the support substrate and the facing member is magnetized. The method for bonding a semiconductor chip and a support substrate according to claim 1.
The support substrate is a magnet and
A method of bonding a semiconductor chip and a support substrate, wherein the facing member is a magnet or an iron plate. The method for bonding a semiconductor chip and a support substrate according to claim 1.
The support substrate is a magnet and
A method of bonding a semiconductor chip and a support substrate, wherein the facing member is a magnet sheet magnetized on both sides. The method for bonding a semiconductor chip and a support substrate according to claim 1.
The support substrate is an iron plate and
A method of bonding a semiconductor chip and a support substrate, wherein the facing member is a magnet. The first step of creating a first patch in which a support substrate made of a ferromagnet and a semiconductor chip are bonded with wax, and
The second step of creating an adsorbent in which the opposing member made of a ferromagnet and the first affix are adsorbed, and
A third step of heating the adsorbent above the melting point of the wax, and
The fourth step of cooling the adsorbent heated in the third step and
A fifth step of pulling the opposing member away from the adsorbent cooled in the fourth step to prepare a second patch in which the semiconductor chip and the support substrate are bonded together.
A sixth step of polishing the surface of the semiconductor chip of the second patch is provided.
A method for polishing a semiconductor chip, characterized in that at least one of the support substrate and the facing member is magnetized. The first step of preparing a first patch in which a support substrate made of a ferromagnet and a semiconductor wafer are bonded with wax, and
The second step of creating an adsorbent in which the opposing member made of a ferromagnet and the first affix are adsorbed, and
A third step of heating the adsorbent above the melting point of the wax, and
The fourth step of cooling the adsorbent heated in the third step and
The present invention includes a fifth step of pulling the opposing member away from the adsorbent cooled in the fourth step to prepare a second sticking material in which the semiconductor wafer and the support substrate are bonded together.
A method of bonding a semiconductor wafer and a support substrate, characterized in that at least one of the support substrate and the facing member is magnetized.

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