Die bonding method for generating conformal waves

Abstract

A die bonding method for generating a conforming wave is disclosed. The die bonding method is used to bond a die to a substrate. The die bonding method includes holding the die with a holding member so that the die corresponds to the substrate, establishing an initial contact between a bonding surface of the die and a conforming surface of the substrate, and generating a conforming wave that spreads from the initial contact. The bonding surface of the die is progressively bonded to the conforming surface of the substrate as the conforming wave spreads.

Description

TECHNICAL FIELD

[0001] The present invention relates to a die bonding method, and in particular, to a die bonding method for generating a conforming wave. BACKGROUND

[0002] Die bonding refers to a process of placing a die on a substrate. In semiconductor manufacturing, a die is usually picked up by a suction nozzle and released on a die bonding site on a substrate to place the die on the substrate. Although many techniques have been developed to improve the accuracy of die picking and alignment, air is often trapped between the contact surface of the die and the substrate when the die is placed on the substrate, resulting in the formation of air bubbles, which not only affects the accuracy of die bonding alignment, but also causes poor contact between the die and the substrate. SUMMARY

[0003] To solve the above problems, the present invention provides a die bonding method for generating a conforming wave, which can effectively remove the air trapped during the process of placing a die on a substrate, thereby inhibiting the formation of air bubbles between the die and the substrate, reducing die bonding errors, and improving die bonding quality.

[0004] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0005] A die bonding method for generating a conforming wave is used to bond a die to a substrate during hybrid bonding for tin-free packaging. The die has an attachment surface, and the substrate has a conforming surface. Both the attachment surface of the die and the conforming surface of the substrate are surfaces without tin balls and copper pillars. The die bonding method comprises the following steps:

[0006] (a) holding the die by a holding member and moving the die and the substrate relative to each other so that the attachment surface of the die corresponds to the conforming surface of the substrate;

[0007] (b) in the state that the die is held by the holding member, the attachment surface of the die is inclined at a contact angle with respect to the conforming surface of the substrate, the attachment surface of the die is brought close to the conforming surface of the substrate, an initial contact is established between one end of the attachment surface of the die and the conforming surface of the substrate, and a conforming wave is generated and spreads from the initial contact; and

[0008] (c) releasing the holding of the die by the holding member, allowing the attachment surface of the die to gradually adhere to the conforming surface of the substrate as the conforming wave spreads, and bonding the die to the substrate.

[0009] An embodiment wherein in step (a), the holding member holds the crystal grain so that the holding member holds a holding surface of the crystal grain, and the holding surface and the attaching surface are opposite surfaces of the crystal grain.

[0010] An embodiment wherein a width of a holding head of the holding member is smaller than a width of the holding surface of the crystal grain, in step (a), the holding member holds the crystal grain so that the holding member holds an end side portion of the holding surface of the crystal grain, and in step (b), the initial contact is established between a holding distal end of the attaching surface of the crystal grain and the attaching surface of the substrate, the holding distal end being an end of the attaching surface distal from the end side portion of the holding surface.

[0011] Another embodiment wherein a width of a holding head of the holding member is smaller than a width of the holding surface of the crystal grain, and in step (a), the holding member holds the crystal grain so that the holding member holds a middle portion of the holding surface of the crystal grain.

[0012] An embodiment wherein in step (b), the contact angle is an angle of less than 45 degrees.

[0013] An embodiment wherein in step (b), the initial contact is an initial contact point.

[0014] Another embodiment wherein in step (b), the initial contact is an initial contact line.

[0015] An embodiment wherein the holding member is a suction nozzle, in step (a), the suction nozzle holds the crystal grain by suction attachment, and in step (c), the suction nozzle releases the holding of the crystal grain by adjusting the holding force of the crystal grain by controlling a variation in negative pressure intensity.

[0016] An embodiment wherein in step (c), the holding member adjusts the holding force of the crystal grain by gradually reducing the negative pressure intensity.

[0017] An embodiment wherein in step (c), the holding member adjusts the holding force of the crystal grain by first reducing the negative pressure intensity and then increasing the negative pressure intensity.

[0018] The present application adopts a technical means of establishing an initial contact between one end of the adhering surface of the die and the adhering surface of the substrate, generating an adhering wave spreading from the initial contact, and gradually adhering the adhering surface of the die to the adhering surface of the substrate along with the spreading of the adhering wave, thereby effectively removing the air trapped in the process of placing the die on the substrate, and inhibiting the formation of air bubbles between the adhering surface of the die and the adhering surface of the substrate, thus reducing the die bonding error and improving the die bonding quality. In a preferred embodiment, the present application uses a suction nozzle as the holding member, and adjusts the holding force of the suction nozzle on the die by controlling the change of the negative pressure intensity of the suction nozzle, thereby controlling the spreading speed of the adhering wave by the pressure difference between the two sides of the die and the elasticity of the die itself. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 is a flowchart showing a die bonding method for generating an adhering wave according to an embodiment of the present application;

[0020] Figure 2 is a schematic diagram showing the execution of die holding according to an embodiment of the present application;

[0021] Figure 2a is another schematic diagram showing the execution of die holding according to an embodiment of the present application;

[0022] Figure 3 is a schematic diagram showing the alignment of the die and the substrate according to an embodiment of the present application;

[0023] Figure 4 is a schematic diagram showing the relative inclination of the die and the substrate according to an embodiment of the present application;

[0024] Figure 5 is a schematic diagram showing the establishment of an initial contact between the die and the substrate according to an embodiment of the present application;

[0025] Figure 6 is a schematic diagram showing the generation of an adhering wave according to an embodiment of the present application;

[0026] Figures 7 to 9 is a schematic diagram showing the gradual adhesion of the die to the substrate according to an embodiment of the present application.

[0027] The reference signs in the drawings are as follows:

[0028] 1, die; 11, adhering surface; 12, holding surface; 2, substrate; 21, adhering surface; 3, holding member; 4, initial contact; S1, holding alignment step; S2, adhering wave generation step; S3, adhesion step; θ, contact angle. DETAILED DESCRIPTION

[0029] The following describes embodiments of the present application in detail according to the drawings. The description is not intended to limit the embodiments of the present application, but is an embodiment of the present application.

[0030] Embodiments

[0031] Please refer to Figures 1 to 9 , the present embodiment provides a method for generating a bonding wave for bonding a die 1 to a substrate 2 in hybrid bonding without soldering. The die 1 has an attachment surface 11, and the substrate 2 has a bonding surface 21. Both the attachment surface 11 of the die 1 and the bonding surface 21 of the substrate 2 are surfaces without solder balls and copper bumps. The method includes a holding alignment step S1, a bonding wave generation step S2, and an attachment step S3.

[0032] Hybrid bonding is a solder-free bonding method compared to the traditional solder bonding method. Since the traditional solder bonding method has reached its limit, in order to reduce the size of the die and the size of the contact points, the direct bonding method has become the preferred solution. However, in the prior art, the direct bonding method is only applied to wafer-to-wafer bonding. In order to facilitate manufacturing, chip-to-wafer bonding is currently in urgent need of development.

[0033] Please refer to Figure 2 and Figure 3 , in the holding alignment step S1, a holding member 3 holds the die 1 (as shown in Figure 2 ), and the die 1 and the substrate 2 are moved relative to each other so that the attachment surface 11 of the die 1 corresponds to the bonding surface 21 of the substrate 2 (as shown in Figure 3 ).

[0034] Specifically, as shown in Figure 2 , in the holding alignment step S1, the holding member 3 holds the die 1 by holding a holding surface 12 of the die 1. The holding surface 12 and the attachment surface 11 are two opposite surfaces of the die 1. In other words, in this embodiment, the die 1 uses the front surface as the attachment surface 11, and the holding member 3 holds the back surface of the die 1.

[0035] In addition, as shown in Figure 3 , the holding member 3 is a holding tool, and the holding tool is a vacuum chuck.As shown, although in this embodiment the holding member 3 moves the die 1 relative to the substrate 2 for alignment, the present invention is not limited thereto. The substrate 2 may move relative to the die 1 held by the holding member 3, or both the die 1 and the substrate 2 may move relative to each other.

[0036] Please refer to the following: Figure 4 , Figure 5 and Figure 6 As shown, in the bonding wave generation step S2, the bonding surface 11 of the die 1 is held by the holding member 3, and the bonding surface 11 of the die 1 is inclined at a contact angle θ relative to the bonding surface 21 of the substrate 2 (e.g., ...). Figure 4 As shown, the attachment surface 11 of the die 1 is brought close to the bonding surface 21 of the substrate 2, and an initial contact 4 is established between one end of the attachment surface 11 of the die 1 and the bonding surface 21 of the substrate 2 (as shown). Figure 5 As shown), and generates a bonding wave that spreads from the initial contact 4 (as shown). Figure 6 (As shown).

[0037] Specifically, such as Figure 4 As shown, although in this embodiment the holding member 3 rotates the die 1 relative to the substrate 2 so that the attachment surface 11 of the die 1 is inclined relative to the bonding surface 21 of the substrate 2, the present invention is not limited thereto. It is also possible that the substrate 2 is rotated relative to the die 1 held by the holding member 3 to a relatively inclined contact angle θ, or that both the die 1 and the substrate 2 are rotated relative to each other to a relatively inclined contact angle θ.

[0038] Furthermore, such as Figure 5 As shown, although in this embodiment the holding member 3 moves the die 1 relative to the substrate 2 so that the attachment surface 11 of the die 1 approaches and contacts the bonding surface 21 of the substrate 2, the present invention is not limited thereto. It is also possible that the substrate 2 moves relative to the die 1 held by the holding member 3 and contacts the die 1, or that the die 1 and the substrate 2 both move relative to each other and approach and contact each other.

[0039] Furthermore, regarding the bond wave technology, since those skilled in the art are already familiar with the concept of bond waves in wafer-to-wafer bonding technology, and related knowledge can also be found in published documents (e.g., International Application Publication No. WO2014191033A1), it will not be elaborated upon further in this document.

[0040] Please refer to the following: Figures 7 to 9As shown, in the attaching step S3, the holding member 3 is released from holding the die 1, and the attaching surface 11 of the die 1 is gradually attached to the attaching surface 21 of the substrate 2 with the spreading of the attaching wave, so as to die attach the die 1 to the substrate 2.

[0041] Specifically, as shown, the attaching wave spreads from the initial contact 4 (as shown), and continuously propagates between the attaching surface 11 of the die 1 and the attaching surface 21 of the substrate 2 (as shown), until spreading to the entire attaching surface 11 of the die 1 (as shown), so that the attaching surface 11 of the die 1 is entirely attached to the attaching surface 21 of the substrate 2, and the air trapped between the attaching surface 11 of the die 1 and the attaching surface 21 of the substrate 2 is effectively removed with the spreading of the attaching wave, so as to achieve good attachment between the die 1 and the substrate 2. Figures 7 to 9 Figure 7 Figure 8 Figure 9

[0042] By the above manner, the present application establishes the initial contact 4 between one end of the attaching surface 11 of the die 1 and the attaching surface 21 of the substrate 2, generates the attaching wave spreading from the initial contact 4, so as to gradually attach the attaching surface 11 of the die 1 to the attaching surface 21 of the substrate 2 with the spreading of the attaching wave, thereby effectively removing the air trapped in the process of placing the die 1 to the substrate 2, and inhibiting the formation of air bubbles between the attaching surface 11 of the die 1 and the attaching surface 21 of the substrate 2, so as to reduce die attach error and improve die attach quality.

[0043] Preferably, as shown in Figure 1 and Figure 2 , the width of a holding head of the holding member 3 is less than the width of the holding surface 12 of the die 1, in the holding alignment step S1, the holding member 3 holds the die 1 by holding one end side portion (for example, the left end in Figure 2 ) of the holding surface 12 of the die 1, and in the attaching wave generating step S2, the initial contact is established between a holding distal end of the attaching surface 11 of the die 1 and the attaching surface 21 of the substrate 2, the holding distal end is the end (i.e., the right end in Figure 2 ) of the attaching surface 11 away from the end side portion of the holding surface 12.

[0044] ​​​​By holding the proximal end of the crystal grain 1 and establishing the initial contact at the distal end of the crystal grain 1, the longest cantilever can be obtained on the limited side length of the crystal grain 1, so as to facilitate the subsequent action of gradually attaching the attachment surface 11 of the crystal grain 1 to the attachment surface 21 of the substrate 2 along the diffusion of the attachment wave in the attaching step S3.

[0045] Of course, the present application is not limited thereto, and as shown in Figure 2a In the holding alignment step S1, the holding member 3 can also hold the crystal grain 1 by holding the middle part of the holding surface 12 of the crystal grain 1.

[0046] Preferably, as shown in Figure 1 and Figure 5 In the attachment wave generation step S2, the initial contact 4 is an initial contact point. In other words, the initial contact 4 is established between an end point of the attachment surface 11 of the crystal grain 1 and the attachment surface 21 of the substrate 2. Of course, the present application is not limited thereto, and the initial contact 4 can also be an initial contact line. In other words, the initial contact 4 is established between an end line of the attachment surface 11 of the crystal grain 1 and the attachment surface 21 of the substrate 2.

[0047] Preferably, as shown in Figure 1 and Figure 4 In the attachment wave generation step S2, the contact angle θ is an angle less than 45 degrees. By reducing the contact angle θ, the amount of air trapped between the attachment surface 11 of the crystal grain 1 and the attachment surface 21 of the substrate 2 can be reduced, and the smooth diffusion of the attachment wave is facilitated, thereby improving the effect of air removal by the attachment wave in the attaching step S3.

[0048] Preferably, as shown in Figure 1 and Figures 6 to 9As shown, in the flip chip method for generating the conformal wave provided by the embodiment, the holding member 3 is a suction nozzle, in the holding and aligning step S1, the suction nozzle holds the die 1 by suction, and in the attaching step S3, the holding member 3 releases the holding of the die 1 by adjusting the holding force of the die 1 by controlling the change of the negative pressure intensity. For example, the holding member 3 releases the holding of the die 1 by gradually reducing the negative pressure intensity to reduce the holding force of the die 1. For another example, the holding member 3 releases the holding of the die 1 by first reducing the negative pressure intensity and then increasing the negative pressure intensity to adjust the holding force of the die 1. Of course, the present application is not limited to this, the negative pressure intensity can be variously changed, and the holding force of the die 1 can be appropriately adjusted according to different situations to release the holding of the die 1 by the holding member 3 and control the spreading of the conformal wave.

[0049] By adjusting the holding force of the die 1 by controlling the change of the negative pressure intensity, the spreading speed of the conformal wave can be effectively controlled by the pressure difference between the two sides of the die 1 (the attaching surface 11 side and the holding surface 12 side) and the elasticity of the die 1 itself, so that the conformal wave can be more smoothly spread to the entire area of the attaching surface 11 of the die 1, thereby improving the effect of driving out the air trapped between the attaching surface 11 of the die 1 and the attaching surface 21 of the substrate 2 by the conformal wave, and achieving further good attachment between the attaching surface 11 of the die 1 and the attaching surface 21 of the substrate 2.

[0050] Finally, it is necessary to point out that the above is only the preferred embodiment of the present application, but the protection scope of the present application is not limited to this, any person skilled in the art can easily think of changes or replacements within the technical scope disclosed by the present application, which should be covered within the protection scope of the present application.

Claims

1. A die bonding method for generating a conformal wave, which is used for bonding a die to a substrate in a hybrid bonding process for a solder-free packaging, wherein the die has an attachment surface, the substrate has a conformal surface, and the attachment surface of the die and the conformal surface of the substrate are both solder ball-free and copper pillar-free surfaces, characterized in that, The method for die bonding comprises the following steps: (a) holding the die by a holding member, and relatively moving the die and the substrate so that the adhering surface of the die corresponds to the adhering surface of the substrate; (b) in the state that the die is held by the holding member, relatively approaching the adhering surface of the die and the adhering surface of the substrate at an angle of a contact angle, establishing an initial contact between one end of the adhering surface of the die and the adhering surface of the substrate, and generating a bonding wave spreading from the initial contact; and (c) releasing the holding of the die by the holding member, and gradually adhering the adhering surface of the die to the adhering surface of the substrate with the spreading of the bonding wave, so as to die bond the die to the substrate.

2. The method of claim 1, wherein: In step (a), the holding member holds the die by a holding surface of the die, and the holding surface and the adhering surface are opposite surfaces of the die.

3. The method of claim 2, wherein: The width of a holding head of the holding member is less than the width of the holding surface of the die, in step (a), the holding member holds the die by one end side portion of the holding surface of the die, and in step (b), the initial contact is established between a holding distal end of the adhering surface of the die and the adhering surface of the substrate, and the holding distal end is the end of the adhering surface away from the end side portion of the holding surface.

4. The method of claim 2, wherein: The width of a holding head of the holding member is less than the width of the holding surface of the die, in step (a), the holding member holds the die by a middle portion of the holding surface of the die.

5. The method of claim 1, wherein: In step (b), the contact angle is less than 45 degrees.

6. The method of claim 1, wherein: In step (b), the initial contact is an initial contact point.

7. The method of claim 1, wherein: In step (b), the initial contact is an initial contact line.

8. The method of claim 1 to 4, wherein: The holding member is a suction nozzle, in step (a), the suction nozzle holds the die by negative pressure adsorption, and in step (c), the holding member releases the holding of the die by adjusting the holding force of the die by controlling the change of the negative pressure intensity.

9. The method of claim 8, wherein: In step (c), the holding member adjusts the holding force of the die by gradually reducing the negative pressure intensity.

10. The method of claim 8, wherein: In step (c), the holding member adjusts the holding force of the die by first reducing the negative pressure intensity and then increasing the negative pressure intensity.

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