CN117174634A - Non-contact type suction head of microchip, preparation method and pasting method - Google Patents

Abstract

The invention discloses a non-contact type suction head of a microchip, a preparation method and a surface mounting method, belongs to the technical field of semiconductor packaging, and solves the problem that the microchip cannot realize non-contact pickup in the prior art. The suction head comprises a first separation body, a second separation body and a vacuum suction disc; the first separating body is provided with an air inlet channel and a horn cavity, and the air inlet channel is connected with the horn cavity; the second separation body is located the air inlet of loudspeaker die cavity, and the second separation body includes jet flow dish and a plurality of arch, and the one side towards loudspeaker die cavity air inlet is located to the arch. The preparation method comprises preparing a first separated body and a second separated body; and (5) assembling. The surface mounting method comprises the steps of picking up the front surface of the microchip by a non-contact suction head; the back of the microchip is arranged on the vacuum contact suction head; the front surface of the microchip is contacted with the wafer for pressurization and pasting. The non-contact suction head, the preparation method and the pasting method can be used for pasting the microchip.

Description

Non-contact type suction head of microchip, preparation method and pasting method

Technical Field

The invention belongs to the technical field of semiconductor packaging, and particularly relates to a non-contact type suction head of a microchip, a preparation method and a surface mounting method.

Background

Chip-to-wafer (D2W) hybrid bonding technology is a core technology that enables high performance three-dimensional heterogeneous integration. The direct bonding of the chips to the wafer is known as direct D2W hybrid bonding. The hybrid bonding is a bonding mode without protruding points, is sensitive to the cleanliness of the bonding surface, and causes a large number of pores at the bonding interface or complete failure of bonding due to pollution generated on the chip surface in the process of bonding.

The method for directly contacting and picking up the chip mainly comprises two modes of front direct contact and peripheral contact, and the following defects exist at present: the front contact mode is difficult to ensure the surface cleanliness requirement of the chip suction head; the chip is picked up in a front contact mode and then needs to be cleaned, so that the efficiency is low and the cost is high; the peripheral contact pick-up mode requires a large space between chips, and severely reduces the number of chips discharged from the wafer.

Currently, the non-contact pick-up method is mainly applied to pick-up and placement of larger-sized products (such as ultrathin wafers and glass jet trays, for example), and cannot be applied to pick-up and placement of micro chips.

Disclosure of Invention

In view of the above analysis, the invention aims to provide a non-contact type suction head of a microchip, a preparation method and a surface mounting method, and solves the problem that the microchip in the prior art cannot realize non-contact pickup.

The aim of the invention is mainly realized by the following technical scheme:

the invention provides a non-contact type suction head of a microchip, which comprises a Bernoulli suction head and a vacuum suction cup for vacuum adsorption of the Bernoulli suction head; the Bernoulli suction head comprises a first separation body and a second separation body; an air inlet channel and a horn cavity are formed in the first separation body, and an air outlet of the air inlet channel is connected with an air inlet of the horn cavity; the second separator is arranged in the horn cavity and positioned at the air inlet of the horn cavity, comprises a jet flow disc and a plurality of bulges, the bulges are arranged on one surface of the jet flow disc, which faces the air inlet of the horn cavity, one end of each bulge is connected with the jet flow disc, and the other end of each bulge is connected with the inner wall of the horn cavity.

Further, the gap size of two adjacent bulges is smaller than the size of the air inlet of the horn cavity.

Further, the Bernoulli suction head has a diameter of 5-100 mm and a height of 4-6 mm.

Further, the microchip has a size of 1 to 100mm×1 to 100mm.

Further, the inclination angle of the side wall of the horn cavity relative to the microchip is 30-45 degrees.

Further, the cross section of the protrusion is circular or arc-shaped.

The invention also provides a preparation method of the non-contact type suction head of the microchip, which is used for preparing the non-contact type suction head and comprises the following steps:

step 1: preparing a first separator and a second separator respectively;

step 2: and assembling the first separation body and the second separation body to obtain the non-contact type suction head of the microchip.

Further, step 1 adopts metal injection molding, metal 3D printing molding or micromachining to prepare the first separator and the second separator, respectively.

Further, in step 2, the first separator and the second separator are assembled by resistance welding or solder welding.

The invention also provides a method for attaching the microchip, which is characterized by adopting the non-contact type suction head of the microchip, and comprises the following steps:

step a: picking up the front surface of the microchip by adopting a non-contact suction head;

step b: placing the back of the microchip on a vacuum contact suction head;

step c: and releasing the front surface of the microchip by the non-contact suction head, and pressing and attaching the front surface of the microchip to the wafer by contacting the front surface of the microchip with the wafer to complete the attaching of the microchip to the wafer.

Compared with the prior art, the invention has at least one of the following beneficial effects:

a) The non-contact type suction head of the microchip provided by the invention is designed to be unique in structure for the microchip, on one hand, the size of the Bernoulli suction head in the prior art is larger, so that the Bernoulli suction head can be used for processing a fluid channel by adopting processes such as drilling, but for the microchip, the Bernoulli suction head cannot be used for processing the microchip by adopting a conventional Bernoulli suction head processing process, the processability is particularly important, the Bernoulli suction head disclosed by the invention divides the whole structure into a first separation body and a second separation body, the air inlet channel and the horn cavity are processed on the first separation body, the further improvement of the air flow rate is realized through the second separation body, and the separation type assembly is adopted for processing and then combining, so that the Bernoulli suction head not only has the Bernoulli adsorption function, but also can be processed and produced in a real sense.

B) According to the non-contact type suction head of the microchip, the horn cavity is used for guiding high-speed air flow, and the high-speed air flow can form a negative pressure area in the center of the horn cavity under the guiding of the side wall of the horn cavity, so that the Bernoulli effect is more favorably generated, and non-contact type pickup is realized.

C) In order to further improve the adsorption force of the Bernoulli suction head, the number of the protrusions is 4, the 4 protrusions are outwards diffused from the dots of the jet disk, the cross section of the protrusions can be in a continuous arc shape, the jet disk is provided with two mutually perpendicular diameter lines, the distance between the intersection point of the first end of each protrusion and one of the diameter lines and the dots of the jet disk is a1, the distance between the intersection point of the second end of each protrusion and the other diameter line and the dots of the jet disk is a2, a1 is more than a2, the distance between the first end and the second end of each protrusion, which are intersected by the same diameter line, is b, in two adjacent protrusions, the diameter of the jet disk is 3.0-3.2 mm, the thickness of each protrusion is 0.4-0.6 mm, a1 is 0.5-0.7 mm, a2 is 0.2-0.3 mm, b is 0.3-0.4 mm, and the height of each protrusion is 0.4-0.5 mm, so that a vacuum area of the jet disk can be formed in the center of the jet disk is 3.5 mm. Like this, adopt the arch of above-mentioned shape and overall arrangement, when high-speed air current passes through the clearance of two adjacent archs, can give high-speed air current tangential velocity for high-speed air current can produce certain rotation, and rotatory high-speed air current can form the vacuum region in the air current center (i.e. the center of loudspeaker die cavity gas outlet), thereby can further improve the front and the reverse pressure differential of microchip, and then can further improve bernoulli suction head's adsorption affinity.

Additional features and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention may be realized and attained by the structure particularly pointed out in the written description and drawings.

Drawings

The drawings are only for purposes of illustrating particular embodiments and are not to be construed as limiting the invention, like reference numerals being used to refer to like parts throughout the several views.

FIG. 1 is a schematic diagram of a non-contact tip of a microchip according to the present invention, wherein the solid arrows indicate the direction of flow of high-velocity gas and the dotted arrows indicate the direction of adsorption force;

FIG. 2 is a schematic diagram showing the structure of a first separator in a non-contact tip of a microchip according to the present invention;

FIG. 3 is a schematic diagram showing the structure of a second separator in a non-contact tip of a microchip according to the present invention;

FIG. 4 is a schematic view showing the arrangement of the bumps in the non-contact tip of the microchip according to the present invention;

FIG. 5 is a schematic view showing the arrangement of the arc-shaped protrusions in the non-contact tip of the microchip according to the present invention;

FIG. 6 is a schematic flow chart of a method for preparing a non-contact tip of a microchip according to the present invention;

fig. 7 is a schematic flow chart of a method for attaching a microchip according to the present invention.

Reference numerals:

1-an air intake passage; 2-a horn cavity; 3-jet disk; 4-bulge; 5-vacuum chuck; 6-microchip; 7-vacuum contact tip; 8-wafer.

Detailed Description

Preferred embodiments of the present invention are described in detail below with reference to the attached drawing figures, which form a part of the present invention and are used in conjunction with the embodiments of the present invention to illustrate the principles of the present invention.

The invention provides a non-contact type suction head of a microchip, which is shown in fig. 1 to 5, and comprises a Bernoulli suction head and a vacuum chuck 5 for vacuum adsorption of the Bernoulli suction head, wherein the Bernoulli suction head comprises a first separation body and a second separation body, the first separation body is provided with an air inlet channel 1 and a horn cavity 2, an air outlet of the air inlet channel 1 is connected with an air inlet of the horn cavity 2, the second separation body is arranged at the air inlet of the horn cavity 2, the second separation body comprises a jet flow disk 3 and a plurality of bulges 4, the bulges 4 are arranged on one surface of the jet flow disk 3 facing the air inlet of the horn cavity 2, one end of each bulge 4 is connected with the jet flow disk 3, and the other end of each bulge 4 is connected with the inner wall of the horn cavity 2.

It will be appreciated that in order to enable an increase in the gas flow rate, the gap size of adjacent two of the projections 4 is smaller than the size of the gas inlet of the horn cavity 2.

During implementation, the air inlet of the air inlet channel 1 is connected with the air supply unit, the microchip 6 is arranged at the air outlet of the horn cavity 2, high-pressure air provided by the air supply unit sequentially passes through the air inlet channel 1, the air inlet of the horn cavity 2 and gaps between two adjacent bulges 4 and flows out of the air outlet of the horn cavity 2 along the side wall of the horn cavity 2, the high-speed air flows out of the air outlet of the horn cavity 2 along the radial direction of the horn cavity 2 after encountering the microchip 6, so that the air flow speed above the microchip 6 is increased, the air pressure on the front surface of the microchip 6 is greater than the air pressure on the back surface of the microchip 6, and the microchip 6 moves towards the direction close to the Bernoulli suction head, thereby realizing the adsorption and pickup of the microchip 6. It should be emphasized that, due to the high-speed air flow between the microchip 6 and the bernoulli tips, the microchip 6 will not contact the bernoulli tips, and contamination of the chip surface by the tips during the chip sucking process can be avoided.

In order to achieve the adsorption of the microchip 6, the Bernoulli tip has a diameter of 5 to 100mm, for example, 5mm, 10mm, 25mm, 40mm, 60mm, 85mm or 100mm, an overall height of 4 to 6mm, a diameter of 1 to 2mm of the air inlet, an outer diameter of 8 to 10mm of the air outlet of the horn cavity 2, and an inner diameter of 3 to 5mm.

The microchip 6 is exemplified by having dimensions (length×width) of 1 to 100mm×1 to 100mm.

Compared with the prior art, the non-contact type Bernoulli suction head of the microchip provided by the invention is designed to the microchip 6, on one hand, the size of the Bernoulli suction head in the prior art is larger, so that the processing of a fluid channel can be realized by adopting processes such as drilling, and the like, but for the microchip 6, the processing performance of the Bernoulli suction head cannot be realized by adopting the conventional Bernoulli suction head processing process, the Bernoulli suction head of the invention is particularly important, the whole structure is divided into a first separation body and a second separation body, the air inlet channel 1 and the horn cavity 2 are processed on the first separation body, the further improvement of the air flow rate is realized by adopting the second separation body, and the separation type assembly is adopted for processing and then the assembly is adopted, so that the Bernoulli suction head not only has the Bernoulli adsorption function, but also can realize the processing and production in a real sense.

In addition, the horn cavity 2 is adopted to guide high-speed air flow, and the high-speed air flow can form a negative pressure area in the center of the horn cavity 2 under the guide of the side wall of the horn cavity 2, so that Bernoulli effect is more favorably generated, and non-contact pickup is realized.

In practical application, the Bernoulli suction head disclosed by the invention is not achievable by adopting integrated processing, and the Bernoulli suction head is processed by adopting a separated assembly and then combined, so that the processing difficulty of the Bernoulli suction head can be greatly reduced.

For the structure of the air inlet channel 1, specifically, the shape of the longitudinal section of the air inlet channel is L-shaped, the air inlet channel comprises a first channel and a second channel, the air inlet end of the first channel is connected with the air supply unit, the air outlet end of the first channel is connected with the air inlet end of the second channel, the air outlet end of the second channel is connected with the horn cavity 2, the axis of the first channel is vertical to the axis of the horn cavity 2, and the second channel is coaxially arranged with the horn cavity 2.

The side wall of the horn cavity 2 is inclined at an angle of 30 to 45 ° with respect to the microchip 6 in consideration of the adsorption force of the bernoulli tips and the flow stability of the high-speed air flow. Thus, the inclination angle of the side wall of the horn cavity 2 relative to the microchip 6 is limited in the above range, on the one hand, the resistance of the side wall of the horn cavity 2 to the high-speed fluid is reduced, the reduction of the flow velocity in the contact process of the high-speed fluid and the horn cavity 2 is reduced, and the adsorption force of the Bernoulli suction head is further ensured, and on the other hand, the flow stability of the high-speed fluid is also ensured, and the adsorption stability of the microchip 6 is further improved.

The number of the above-mentioned projections 4 may be 3 to 6, for example, 4, and the shape of the cross section of the projection 4 may be circular or arc-shaped, for example.

The cross-section of the above-mentioned projection 4 may be circular in shape in view of flow resistance and flow stability of the high-speed air flow. This is because the rounded side walls of the protrusions 4 have no corners, and can better guide the high-speed fluid, thereby ensuring the flow resistance and the flow stability of the high-speed air flow. Illustratively, the diameter of the jet disk 3 is 3.0-3.2 mm, the thickness is 0.4-0.6 mm, the gap width of two adjacent protrusions 4 is 0.5-0.6 mm, and the gap height is 0.5-0.6 mm.

In order to further increase the adsorption force of the bernoulli suction head, the number of the protrusions 4 is 4, the protrusions 4 are dispersed outwards from the dots of the jet disk 3, the cross section of the protrusions 4 may be in a continuous arc shape, the jet disk 3 has two mutually perpendicular diameter lines, the distance between the intersection point of the first end of the protrusion 4 and one of the diameter lines and the dots of the jet disk 3 is a1, the distance between the intersection point of the second end of the protrusion 4 and the other diameter line and the dots of the jet disk 3 is a2, a1 > a2, the distance between the first end and the second end of the adjacent two protrusions 4 intersecting the same diameter line is b, and the diameter of the jet disk 3 is 3.0-3.2 mm, the thickness is 0.4-0.6 mm, a1 is 0.5-0.7 mm, a2 is 0.2-0.3 mm, b is 0.3-4 mm, and the height of the protrusions 4 is 0.4-0.5 mm, so that a vacuum area of 3.5mm can be formed in the center of the jet disk 3.3-3 mm. Like this, adopting protruding 4 of above-mentioned shape and overall arrangement, when high-speed air current passes through the clearance of two adjacent protruding 4, can give high-speed air current tangential velocity for high-speed air current can produce certain rotation, and rotatory high-speed air current can form the vacuum region in the air current center (i.e. the center of loudspeaker die cavity 2 gas outlet), thereby can further improve the pressure differential of the front and the reverse side of microchip 6, and then can further improve bernoulli suction head's adsorption affinity.

For the material of the first separator and the second separator, specifically, stainless steel, aluminum alloy, or copper alloy may be used for both.

The invention also provides a preparation method of the non-contact type suction head of the microchip, which comprises the following steps of:

step 1: adopting metal injection molding, metal 3D printing molding or micromachining to prepare a first separator and a second separator respectively;

step 2: and assembling the first separation body and the second separation body by adopting a resistance welding mode or a solder welding mode to obtain the non-contact type suction head of the microchip.

Compared with the prior art, the beneficial effects of the preparation method of the non-contact type suction head of the microchip provided by the invention are basically the same as those of the non-contact type suction head of the microchip provided by the invention, and are not repeated herein.

For metal injection molding, the above step 1 includes the steps of:

step 11: preparing a first separator mold and a second separator mold according to the shape and the size of the first separator and the second separator;

step 12: injecting the raw material (stainless steel, aluminum alloy or copper alloy powder with the particle size of 0.1-100 μm) of the first separator into a first separator die, and adopting the first separator die to perform injection molding on the first separator to obtain a first separator to be treated;

injecting the raw material (stainless steel, aluminum alloy or copper alloy powder with the particle size of 0.1-100 μm) of the second separator into a second separator mold, and adopting the second separator mold to perform injection molding on the second separator to obtain a second separator to be treated;

the injection molding forming agent is a wax-based forming agent or a resin-based forming agent;

step 13: degreasing the formed first separation body to be treated and the formed second separation body to be treated by adopting a thermal degreasing (degreasing temperature is 40-80 ℃) or acetone-based solvent;

step 14: sintering and molding the degreased first separator to be treated and the degreased second separator to obtain the first separator and the second separator.

For 3D printing molding, the step 1 includes the steps of:

step 11': designing a 3D printing program according to the shapes and the sizes of the first separation body and the second separation body;

step 12': printing a first separator to be treated and a second separator to be treated according to a 3D printing program by adopting raw materials (stainless steel, aluminum alloy or copper alloy powder with the particle size of 0.1-100 mu m);

step 13': sintering and forming the first separator to be treated and the second separator to be treated to obtain the first separator and the second separator.

It should also be noted that the sintering temperatures adopted by the different raw materials are also different, specifically, the sintering processes are respectively: the raw material is stainless steel, the sintering temperature is 1000-1400 ℃, the raw material is aluminum alloy, the sintering temperature is 300-500 ℃, the raw material is copper alloy, and the sintering temperature is 500-800 ℃.

For micromachining, step 1 described above includes the steps of:

and respectively processing the first separator and the second separator by adopting a numerical control processing center and a miniature cutter.

In order to ensure the connection stability between the first separator and the second separator, the first separator and the second separator are assembled in a resistance welding mode, and specific process parameters are as follows: the resistance welding pressure is 10-500 gf, and the resistance welding power is 50-200W.

The first separating body and the second separating body are assembled in a solder welding mode, and specific technological parameters are as follows: and plating nickel on the surfaces of the first separator and the second separator, wherein the thickness of the plating layer is 0.5-10 mu m, the solder is tin-based solder, and the welding temperature is 150-350 ℃.

The invention also provides a method for attaching the microchip, referring to fig. 7, the method for attaching the microchip comprises the following steps of:

step a: the front surface of the microchip 6 is picked up by a non-contact suction head, so that the microchip 6 is separated from the blue film, and the air pressure of the air inlet is 0.15-1 MPa;

step b: placing the back of the microchip 6 on the vacuum contact tip 7;

step c: the non-contact suction head releases the front surface of the microchip 6, the front surface of the microchip 6 is contacted with the wafer 8 for pressurizing and pasting, the pressure is 1-1000N, the size of the wafer 8 is 8 inches or 12 inches, the pasting of the microchip 6 to the wafer 8 is completed, and the hybrid bonding of the microchip 6 to the wafer 8 is realized.

Compared with the prior art, the beneficial effects of the chip attaching method of the microchip provided by the invention are basically the same as those of the non-contact type suction head of the microchip provided by the invention, and are not repeated here.

Example 1

Specific dimensions of the non-contact tip of this embodiment are as follows:

the whole diameter of non-contact suction head is 10mm, and whole height is 4mm, and the diameter of air inlet is 1mm, and the external diameter of loudspeaker die cavity gas outlet is 9mm, and the internal diameter is 4mm, and loudspeaker die cavity lateral wall is 30 for microchip's inclination, and jet disc's diameter is 3mm, and jet disc's thickness is 0.5mm, and bellied quantity is 4, and the shape is circular, and two adjacent bellied gap width is 0.5, and the gap height is 0.5mm.

Example two

Specific dimensions of the non-contact tip of this embodiment are as follows:

the whole diameter of the non-contact suction head is 10mm, the whole height is 4mm, the diameter of the air inlet is 1mm, the outer diameter of the air outlet of the horn cavity is 9mm, the inner diameter is 4mm, the inclination angle of the side wall of the horn cavity relative to the microchip is 45 degrees, the diameter of the jet flow disk is 3.2mm, the thickness of the jet flow disk is 0.4mm, the number of the protrusions is 4, the shape is arc-shaped, a1 is 0.6mm, a2 is 0.3mm, b is 0.3mm, the height of the protrusions is 0.5mm, and the diameter of a vacuum area formed in the center of the jet flow disk is 3.2mm.

Example III

The preparation method of the present embodiment is used for the preparation of the non-contact type suction head of the first embodiment, and includes the following steps:

preparing a first separator mold and a second separator mold according to the shape and the size of the first separator and the second separator;

respectively injecting stainless steel with the particle size of 50 mu m into a first separator die and a second separator die, wherein the injection molding agent is a wax-based molding agent, so as to obtain a first separator to be treated and a second separator to be treated; the method comprises the steps of carrying out a first treatment on the surface of the

Thermal degreasing is adopted for the first separation body to be treated and the second separation body to be treated after molding (degreasing temperature is 40 ℃);

sintering and forming the degreased first separator to be treated and the degreased second separator to be treated, wherein the sintering temperature is 1200 ℃, and the first separator and the second separator are obtained;

and assembling the first separation body and the second separation body by adopting a resistance welding mode to obtain the non-contact type suction head of the microchip, wherein the resistance welding pressure is 500gf, and the resistance welding power is 100W.

Example IV

The non-contact type suction head of the first embodiment is used for pasting a microchip, the size (length×width) of the microchip is 10×10mm, and the pasting method comprises the following steps:

the front surface of the microchip is picked up by a non-contact suction head, so that the microchip is separated from the blue film, and the air pressure of an air inlet is 1MPa;

placing the back of the microchip on a vacuum contact suction head;

the non-contact suction head releases the front surface of the microchip, the front surface of the microchip is contacted with the wafer to carry out pressurization patch, the pressure is 500N, the wafer size is 8 inches, the patch from the microchip to the wafer is completed, and the hybrid bonding from the microchip to the wafer is realized.

The present invention is not limited to the above-mentioned embodiments, and any changes or substitutions that can be easily understood by those skilled in the art within the technical scope of the present invention are intended to be included in the scope of the present invention.

Claims (10)

1. A non-contact tip for a microchip, comprising a bernoulli tip and a vacuum chuck for vacuum adsorption of the bernoulli tip; the Bernoulli tip comprises a first separator and a second separator;

an air inlet channel and a horn cavity are formed in the first separation body, and an air outlet of the air inlet channel is connected with an air inlet of the horn cavity;

the second separation body is arranged in the horn cavity and is positioned at the air inlet of the horn cavity, the second separation body comprises a jet flow disc and a plurality of bulges, the bulges are arranged on one surface of the jet flow disc, which faces the air inlet of the horn cavity, one end of each bulge is connected with the jet flow disc, and the other end of each bulge is connected with the inner wall of the horn cavity.

2. The microchip non-contact tip of claim 1, wherein the gap size of two adjacent protrusions is smaller than the size of the air inlet of the horn cavity.

3. The non-contact tip of the microchip according to claim 1, wherein the bernoulli tip has a diameter of 5 to 100mm and a height of 4 to 6mm.

4. The non-contact tip of a microchip according to claim 1, wherein the microchip has a size of 1 to 100mm x 1 to 100mm.

5. The non-contact tip of a microchip according to claim 1, wherein the sidewall of the horn cavity is inclined at an angle of 30-45 ° with respect to the microchip.

6. The non-contact tip of the microchip according to claim 1, wherein the cross-section of the protrusion is circular or arc-shaped.

7. A method for preparing a non-contact tip for a microchip, characterized by comprising the steps of:

step 1: preparing a first separator and a second separator respectively;

step 2: and assembling the first separation body and the second separation body to obtain the non-contact type suction head of the microchip.

8. The method for manufacturing a non-contact tip for a microchip according to claim 7, wherein the step 1 is to manufacture the first separator and the second separator by metal injection molding, metal 3D printing molding or micromachining, respectively.

9. The method of manufacturing a non-contact tip for a microchip according to claim 7, wherein in step 2, the first separator and the second separator are assembled by resistance welding or solder welding.

10. A method of mounting a microchip, characterized by using the noncontact tip of the microchip according to any one of claims 1 to 6, comprising the steps of:

step a: picking up the front surface of the microchip by adopting a non-contact suction head;

step b: placing the back of the microchip on a vacuum contact suction head;

step c: and releasing the front surface of the microchip by the non-contact suction head, and pressing and attaching the front surface of the microchip to the wafer by contacting the front surface of the microchip with the wafer to complete the attaching of the microchip to the wafer.