JP2009016534A - Laminating method, and laminating substrate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To laminate a wafer to a laminating wafer in parallel to each other to prevent leakage of an adhesive. <P>SOLUTION: On the laminating wafer S, a plurality of through-holes 50 penetrating it in its thickness direction are formed, and a thermosetting adhesive A is embedded in the through-holes 50. In a laminating process, laminating surfaces of the laminating wafer S and a wafer W are laminated on each other. Thereafter, the thermosetting adhesive A of the laminating wafer S is heated and melted, and the thermosetting adhesive A is run between the laminating wafer S and the wafer W. Thereafter, the thermosetting adhesive A is cooled and hardened to attach the wafer W to the laminating wafer S. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for bonding a substrate and a bonding substrate, and a bonding substrate used in the bonding method.

  For example, in the semiconductor device manufacturing process, semiconductor wafers (hereinafter referred to as “wafers”) are being made larger and thinner.

  For example, when a thin wafer having a large diameter is transported or polished, the wafer may be warped or cracked. For this reason, it is necessary to reinforce the wafer by bonding the wafer to the same bonding substrate. For example, when the wafer is thinly ground, it is difficult to directly hold the wafer. In this case, it is necessary to attach the wafer to the bonding substrate.

  The above-mentioned wafer and bonding substrate are bonded by placing a solid thermoplastic adhesive on the wafer, melting the thermoplastic adhesive by heat, and aligning the bonding substrate with the wafer. Thereafter, the adhesive was cooled and solidified (see Patent Document 1).

JP 2005-51055 A

  However, if the solid thermoplastic adhesive is melted on the wafer as described above, the distribution of the adhesive may vary within the wafer surface, and the wafer and the bonding substrate cannot be bonded in parallel. Sometimes. In particular, the place where the solid thermoplastic adhesive is placed tends to be thick. If the wafer and the bonding substrate are not parallel, the wafer is not evenly ground, for example, when grinding for thinning, and the thickness of the wafer varies.

  Further, in order to ensure that the thermoplastic adhesive spreads over the entire surface of the wafer, the amount of the adhesive is usually set to be large. For this reason, when the wafer and the bonding substrate are bonded together, excess adhesive may leak from the outer peripheral portion of the bonding surface, and the wafer or the bonding substrate may be soiled. For example, when the back surface of the wafer is contaminated, the wafer level is not ensured when held by the chuck, and the wafer processing may not be performed uniformly in the surface.

  This invention is made | formed in view of this point, and it aims at bonding a board | substrate, such as a wafer, and its bonding substrate so that it may be parallel and there may be no leakage of an adhesive agent.

  The present invention for achieving the above object is a method of bonding a substrate and a substrate for bonding, having a plurality of through holes penetrating in the thickness direction, and a thermoplastic adhesive embedded in the through holes A step of aligning the bonding substrate and the bonding surfaces of the substrate, and then heating and melting the thermoplastic adhesive in the through-hole of the bonding substrate to form the bonding substrate and the substrate And a step of pouring the thermoplastic adhesive between and a step of cooling and solidifying the thermoplastic adhesive.

  According to the present invention, the thermoplastic adhesive in the through-hole of the bonding substrate flows between the bonding substrate and the substrate due to the capillary phenomenon, so that the thermoplastic adhesive diffuses uniformly on the bonding surface. To do. As a result, the bonding substrate and the substrate are bonded in parallel. In addition, since the thermoplastic adhesive flows only into the gap between the bonding substrate and the substrate due to the action of capillary action, it does not leak to the outside of the bonding surface, and the substrate and the bonding substrate are contaminated by the adhesive. Can be prevented.

  In the bonding method, the thermoplastic adhesive may be melted in a reduced pressure atmosphere.

  Further, in the step of pouring the thermoplastic adhesive between the bonding substrate and the substrate, by adjusting the pressure of the ambient atmosphere of the thermoplastic adhesive, between the bonding substrate and the substrate The thickness of the thermoplastic adhesive may be controlled.

  The present invention according to another aspect is a bonding substrate to be bonded to a substrate, and has a plurality of through holes penetrating in a thickness direction, and a thermoplastic adhesive is embedded in the through holes. It is characterized by being.

  The plurality of through holes may be evenly arranged in the bonding substrate surface.

  The bonded substrate may be a silicon substrate.

  According to the present invention, since the substrate and the bonding substrate are bonded in parallel so that there is no leakage of the adhesive, the subsequent processing of the substrate is performed appropriately, and the yield is improved.

  Hereinafter, preferred embodiments of the present invention will be described. FIG. 1 is an explanatory view of a longitudinal section showing an outline of a configuration of a bonding apparatus 1 in which a bonding method according to the present embodiment is performed.

  The laminating apparatus 1 has a processing container 10 that can be hermetically closed, for example. In the center of the processing container 10, for example, a mounting table 20 is provided. The mounting table 20 has, for example, a thick and substantially disk shape, and a flat surface is formed on the upper surface thereof. The wafer W can be placed on this flat surface.

  Inside the mounting table 20, a heater 31 is built in which generates heat when power is supplied from the power source 30. The heater 31 can heat the wafer W on the mounting table 20 and a bonding wafer S to be described later.

  In addition, a refrigerant flow path 33 through which a refrigerant supplied from, for example, a refrigerant supply device 32 flows is formed inside the mounting table 20. Thereby, the wafer W and the bonding wafer S on the mounting table 20 can be cooled.

  As shown in FIG. 1, an exhaust pipe 40 is connected to the side wall surface of the processing container 10. The exhaust pipe 40 is connected to a negative pressure generator 41 such as a vacuum pump. Thereby, the inside of the processing container 10 can be depressurized to a predetermined pressure.

  Next, the configuration of the bonding wafer S to be bonded to the wafer W will be described.

  The bonding wafer S has a circular shape that is the same shape as the wafer W, for example, as shown in FIGS. The same silicon wafer as the wafer W is used as the base material of the bonding wafer S. The bonding wafer S has a thickness of about 300 μm, for example.

  In the bonding wafer S, a plurality of through holes 50 penetrating in the thickness direction are formed. The through holes 50 are, for example, circular holes having a diameter of about 500 μm, and are evenly arranged in the bonding wafer S surface. For example, as shown in FIG. 2, a plurality of through holes 50 are arranged at equal intervals on the same circumference with the center of the bonding wafer S as a center, and a plurality of through holes 50 on the same circumference are arranged concentrically. It is piled up. A thermoplastic adhesive A is embedded in each of these through holes 50.

  In the bonding wafer S, for example, a through hole 50 is formed on a silicon wafer as a base material by etching, drilling, laser processing, or the like, and the molten thermoplastic adhesive A is poured into the through hole 50, and then thermoplastic. It is manufactured by solidifying the adhesive A.

  Next, a bonding process between the wafer W and the bonding wafer S performed using the bonding apparatus 1 and the bonding wafer S will be described.

  First, as shown in FIGS. 1 and 4, the wafer W is placed on the placing table 20 in the processing container 10, and the bonding wafer S is placed thereon. Thereby, the bonding surfaces of the wafer W and the bonding wafer S are aligned. At this time, the temperature of the mounting table 20 is maintained at a temperature lower than the melting temperature (for example, 70 ° C.) of the thermoplastic adhesive A, for example, about room temperature (for example, about 25 ° C.).

  Next, exhaust from the exhaust pipe 40 is started and the inside of the processing container 10 is depressurized. Then, the heater 31 generates heat, and the temperature of the wafer W and the bonding wafer S rises. The wafer W and the bonding wafer S are heated to the melting temperature of the thermoplastic adhesive A or higher, for example, 70 ° C. or higher, and the thermoplastic adhesive A in the through hole 50 of the bonding wafer S is melted. At this time, the pressure in the processing container 10 is reduced from, for example, normal pressure to about −90 kPa.

  When the thermoplastic adhesive A melts, the melted thermoplastic adhesive A flows out from the inside of each through hole 50 by capillary action and flows into the gap between the wafer W and the bonding wafer S as shown in FIG. At this time, the thermoplastic adhesive A is uniformly diffused over the entire bonding surface of the wafer W and the bonding wafer S by the action of capillary action. Further, the thermoplastic adhesive A spreads only in the region where the capillary phenomenon acts, that is, in the gap between the wafer W and the bonding wafer S, and does not leak outside the bonding surface.

  Thereafter, the pressure in the processing container 10 is returned to atmospheric pressure, and then the coolant is caused to flow through the coolant channel 33, whereby the wafer W on the mounting table 20 and the bonding wafer S are solidified by the thermoplastic adhesive A. Then, for example, it is cooled to room temperature, and the thermoplastic adhesive A is solidified as shown in FIG. As a result, the wafer W and the bonding wafer S are bonded and bonded together, and a series of bonding processing is completed.

  In the above embodiment, the bonding surfaces of the bonding wafer S and the wafer W in which the thermoplastic adhesive A is embedded in the through hole 50 are combined, and then the thermoplastic adhesive A is heated and melted. It is poured into the gap between the wafer W and the bonding wafer S, and then the thermoplastic adhesive A is cooled and solidified, and the wafer W and the bonded wafer S are bonded together. According to the present embodiment, since the thermoplastic adhesive A is uniformly diffused to the bonding surface of the wafer W and the bonding wafer S by capillary action, the thickness of the thermoplastic adhesive A becomes uniform, The wafer W and the bonding wafer S are bonded in parallel. Further, since the thermoplastic adhesive A flows only into the region where the capillary phenomenon acts, the thermoplastic adhesive A is supplied only to the gap between the wafer W and the bonding wafer S, and the thermoplastic adhesive is externally supplied from the bonding surface. A can be prevented from leaking.

  Further, since the thermoplastic adhesive A flows into only a slight gap between the wafer W and the bonding wafer S, the film thickness of the thermoplastic adhesive A becomes thin, and the amount of the thermoplastic adhesive A used can be reduced.

  Further, as shown in FIG. 6, the thermoplastic adhesive A is solidified in the bonding surface of the wafer W and the bonding wafer S and in the through hole 50. For this reason, the contact area between the thermoplastic adhesive A, the wafer W and the bonding wafer S is widened, and the adhesive force between the wafer W and the bonding wafer S is increased. Finally, since the through hole 50 of the bonding wafer S is fitted into the convex portion on the upper surface of the thermoplastic adhesive A, the strength in the displacement direction of the wafer W and the bonding wafer S is also improved. Go up.

  In the above embodiment, when the thermoplastic adhesive A is melted, the inside of the processing container 10 is in a reduced pressure atmosphere, so that bubbles in the melted thermoplastic adhesive A can be removed. Thereby, bubbles do not remain in the solidified thermoplastic adhesive A, and a strong adhesive force between the wafer W and the bonding wafer S can be secured.

  In the bonding wafer S used in the above embodiments, a plurality of through holes 50 are formed, and the thermoplastic adhesive A is embedded in the through holes 50, so that the thermoplastic adhesive A is melted. Then, it flows properly between the wafer W and the bonding wafer S. Further, since the plurality of through holes 50 are evenly arranged in the wafer surface for bonding, the melted thermoplastic adhesive A is evenly supplied in the wafer surface and bonded to the wafer W after bonding. The parallelism of the wafer S can be further improved.

  Further, since the bonding wafer S is composed of the same silicon wafer as the wafer W, the thermal expansion coefficients of the wafer W and the bonding wafer S are almost the same. For example, the bonding wafer S and the bonding wafer S are bonded. Warpage and damage due to thermal expansion and contraction of the alignment wafer S are prevented.

  In the above embodiment, the thickness of the thermoplastic adhesive A between the wafer W and the bonding wafer S is adjusted by adjusting the pressure in the ambient atmosphere of the thermoplastic adhesive A when the thermoplastic adhesive A is melted. You may control. It has been confirmed that increasing the pressure in the surrounding atmosphere increases the thickness of the thermoplastic adhesive A, and decreasing the pressure in the surrounding atmosphere decreases the thickness of the thermoplastic adhesive A. Therefore, when the thermoplastic adhesive A is thinned, the pressure inside the processing container 10 is lowered, and when the thermoplastic adhesive A is thickened, the pressure inside the processing container 10 is raised. By doing so, the thermoplastic adhesive A between the wafer W and the bonding wafer S can be made to have a desired thickness, for example, depending on the required adhesive strength and the amount of adhesive used.

  The preferred embodiments of the present invention have been described above with reference to the accompanying drawings, but the present invention is not limited to such examples. It will be apparent to those skilled in the art that various changes and modifications can be made within the scope of the ideas described in the claims, and these are naturally within the technical scope of the present invention. It is understood that it belongs.

  For example, in the above embodiment, the example in which the wafer W is bonded to one side of the bonding wafer S has been described. However, in the present invention, the wafer W is bonded to both surfaces of the bonding wafer S as shown in FIG. It is also applicable when attaching. Further, the configuration of the through hole 50 of the bonding wafer S is not limited to the above example, and may have other shapes and other arrangements. The present invention can also be applied to the case where a substrate such as an FPD (flat panel display) other than a wafer is bonded to the bonding substrate.

  The present invention is useful when a substrate and a bonding substrate are bonded together.

It is explanatory drawing of the longitudinal cross-section which shows the outline of a structure of the bonding apparatus. It is a top view of the wafer for bonding. It is explanatory drawing of the longitudinal cross-section of the wafer for bonding. It is explanatory drawing which shows a mode that the wafer for bonding was mounted on the wafer. It is explanatory drawing which shows a mode that the molten thermoplastic adhesive flows between a wafer and the wafer for bonding. It is explanatory drawing which shows a mode that the thermoplastic adhesive was solidified. It is explanatory drawing which shows what bonded the wafer on both surfaces of the wafer for bonding.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Bonding apparatus 10 Processing container 20 Mounting stand 31 Heater 50 Through-hole S Wafer for bonding W Wafer A Thermoplastic adhesive

Claims (6)

A method of bonding a substrate and a bonding substrate,
A step of having a plurality of through holes penetrating in the thickness direction and aligning the bonding surfaces of the bonding substrate and the substrate in which the thermoplastic adhesive is embedded in the through holes; and
Thereafter, heating and melting the thermoplastic adhesive in the through-hole of the bonding substrate, and pouring the thermoplastic adhesive between the bonding substrate and the substrate;
And then solidifying the thermoplastic adhesive by cooling. The bonding method according to claim 1, wherein the thermoplastic adhesive is melted in a reduced-pressure atmosphere. In the step of pouring the thermoplastic adhesive between the bonding substrate and the substrate, by adjusting the pressure of the ambient atmosphere of the thermoplastic adhesive, the bonding substrate and the substrate The bonding method according to claim 1, wherein the thickness of the thermoplastic adhesive is controlled. A bonding substrate to be bonded to the substrate,
Having a plurality of through holes penetrating in the thickness direction,
A bonding substrate, wherein a thermoplastic adhesive is embedded in the through hole. 5. The bonding substrate according to claim 4, wherein the plurality of through holes are evenly arranged in the bonding substrate surface. The bonded substrate according to claim 4 or 5 is a silicon substrate.

Images