Board body bonding method

Abstract

The invention relates to a plate body bonding method, which is used for bonding a first substrate and a second substrate. The method includes: placing the first substrate on a carrier in a closed chamber; exhausting air in the closed cavity to reduce the air pressure of the closed cavity to a preset low pressure value; placing a second substrate on the first substrate; applying pressure to the second substrate so as to press the second substrate to the first substrate; enabling the gas of the external atmosphere to slowly enter the closed chamber at a first fluid coefficient; the gas of the external atmosphere quickly enters the closed chamber at a second fluid coefficient; wherein the second fluid coefficient is greater than the first fluid coefficient.

Description

Technical Field

[0001] The invention relates to the bonding of plates, and in particular to a plate bonding method. Background Art

[0002] In the wafer manufacturing process, it is often necessary to bond two plates together with adhesives before performing subsequent processing. Taking the wafer thinning process as an example, the stress strength of the wafer to be thinned is insufficient and it is easy to break. Therefore, before the thinning operation, the wafer will be bonded to the carrier substrate to improve the mechanical strength, and then the wafer will be subjected to thinning operations such as chemical mechanical polishing.

[0003] As mentioned above, the wafer and the carrier substrate are bonded with an adhesive. The adhesive must be fully adhered to the wafer and the carrier substrate, and the air between the wafer and the carrier substrate must be evacuated to avoid bubbles in the adhesive that affect the bonding strength.

[0004] The existing practice is to place the wafer and the carrier substrate in a sealed chamber during the bonding process. While applying pressure to the two substrates, the sealed chamber is simultaneously evacuated to a low pressure, so that the bubbles are attracted by the low pressure and move toward the edge of the substrate, and finally the air between the wafer and the carrier substrate is removed from the edge of the substrate.

[0005] However, in the process of restoring the pressure of the closed chamber to normal pressure (reaching equilibrium with the external atmospheric pressure), gas often re-enters between the wafer and the carrier substrate to form new bubbles, which affect the bonding strength. Summary of the invention

[0006] In order to solve the above technical problem, the present invention provides a plate bonding method, which can fully remove the air between two bonded plates.

[0007] The present invention provides a plate bonding method for bonding a first substrate and a second substrate. The method comprises: placing the first substrate on a carrier in a closed chamber; evacuating the closed chamber to reduce the air pressure in the closed chamber to a predetermined low pressure value; placing the second substrate on the first substrate; applying pressure to the second substrate to press the second substrate onto the first substrate; allowing the gas from the outside atmosphere to slowly enter the closed chamber at a first fluid coefficient; and allowing the gas from the outside atmosphere to quickly enter the closed chamber at a second fluid coefficient; wherein the second fluid coefficient is greater than the first fluid coefficient.

[0008] Preferably, the step of providing a sealed chamber includes providing a vacuum chamber, wherein the sealed chamber is formed inside the vacuum chamber.

[0009] Preferably, the first substrate is firstly disposed on a carrying surface of a carrying platform, and the carrying platform is disposed at the bottom of the vacuum chamber, and the carrying surface faces the top of the vacuum chamber.

[0010] Preferably, the step of evacuating the sealed chamber includes connecting a vacuum pump to the sealed chamber via an evacuation pipeline, and evacuating the chamber using the vacuum pump.

[0011] Preferably, the step of applying pressure to the second substrate includes movably disposing a bonding head on the top of the vacuum chamber so that the bonding head moves toward the carrier platform to contact the second substrate.

[0012] Preferably, the step of allowing the gas of the external atmosphere to flow in includes connecting the closed chamber with a two-stage valve assembly; wherein the fluid coefficient of the two-stage valve assembly can be switched between a first fluid coefficient and a second fluid coefficient, and the second fluid coefficient is greater than the first fluid coefficient.

[0013] Preferably, the two-stage valve assembly includes: a first opening and closing valve and a throttle valve, which are connected in series to the intake pipeline, and the first opening and closing valve is located between the intake pipeline and the throttle valve, and the fluid coefficient formed by the first opening and closing valve and the throttle valve being connected in series is equal to the first fluid coefficient; and a second opening and closing valve, whose two ends are respectively connected to the inlet end of the first opening and closing valve and the outlet end of the throttle valve, and when the first opening and closing valve and the second opening and closing valve are opened at the same time, the two-stage valve assembly has a second fluid coefficient.

[0014] Preferably, the step of allowing the gas from the outside atmosphere to slowly enter the closed chamber at a first fluid coefficient includes: opening the first on-off valve to allow the gas from the outside atmosphere to enter the closed chamber through the throttle valve and the first on-off valve.

[0015] Preferably, the step of allowing the gas from the outside atmosphere to quickly enter the closed chamber at a second fluid coefficient includes: opening the second on-off valve to allow the gas from the outside atmosphere to enter the closed chamber simultaneously through the first on-off valve, the second on-off valve and the throttle valve.

[0016] Furthermore, the board bonding method further includes coating an adhesive on the first substrate or the second substrate, so that the adhesive is located between the first substrate and the second substrate.

[0017] Through the board bonding method proposed in the present invention, the air between the two bonded substrates can be fully removed, and at the same time, it is prevented that the air re-enters between the two substrates during the pressure recovery process, thereby effectively improving the bonding yield. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a cross-sectional schematic diagram of a board bonding machine in an embodiment of the present invention.

[0019] Figure 2 1 is another cross-sectional schematic diagram of the board bonding machine in the embodiment of the present invention.

[0020] Figure 3It is another cross-sectional schematic diagram of the board bonding machine in the embodiment of the present invention.

[0021] Figure 4 It is a flow chart of a method for bonding a plate in an embodiment of the present invention.

[0022] Figure 5 It is a cross-sectional schematic diagram of a board bonding machine, used to reveal some steps of the board bonding method.

[0023] Figure 6 and Figure 7 It is a partial cross-sectional schematic diagram of a board bonding machine, used to reveal some steps of the board bonding method.

[0024] Explanation of the reference numerals: 100-board bonding machine; 100a-vacuum chamber; 100b-sealed chamber; 110-lower chamber; 120-upper chamber; 130-carrying platform; 140-bonding head; 150-exhaust pipeline; 160-intake pipeline; 170-two-stage valve assembly; 171-first opening and closing valve; 172-second opening and closing valve; 173-throttle valve; 180-linear actuator; 182-actuating rod; 190-vacuum pump; B-bubble; Cv1-first fluid coefficient; Cv2-second fluid coefficient; G-adhesive; S1-first substrate; S2-second substrate; S110~S160-steps. DETAILED DESCRIPTION

[0025] See also Figure 1 , Figure 2 and Figure 3 As shown, a board bonding machine 100 for board bonding disclosed in an embodiment of the present invention is used to perform a board bonding method to bond a first substrate S1 and a second substrate S2. The first substrate S1 and the second substrate S2 can be a wafer to be thinned and a carrier substrate for enhancing mechanical strength, but are not limited thereto. It should be noted that the proportions of the first substrate S1 and the second substrate S2 are drawn in the figure to make the present invention easier to understand, and do not represent the actual size proportions of the first substrate S1 and the second substrate S2.

[0026] like Figure 1 , Figure 2 and Figure 3 As shown, the board bonding machine 100 comprises a lower cavity 110 , an upper cavity 120 , a carrier 130 , a bonding head 140 , an exhaust pipeline 150 , an air intake pipeline 160 and a two-stage valve assembly 170 .

[0027] like Figure 1 , Figure 2 and Figure 3As shown, the lower cavity 110 and the upper cavity 120 are used to combine into a vacuum cavity 100a, and a closed chamber 100b is formed inside the vacuum cavity 100a. The lower cavity 110 constitutes the bottom of the vacuum cavity 100a, and the upper cavity 120 constitutes the top of the vacuum cavity 100a. The carrying platform 130 is arranged at the bottom of the vacuum cavity 100a, that is, the carrying platform 130 is arranged on the lower cavity 110, and the carrying platform 130 is arranged in the closed chamber 100b. The carrying surface 132 of the carrying platform 130 faces the top of the vacuum cavity 100a, that is, the carrying surface 132 faces the upper cavity 120. The carrying surface 132 of the carrying platform 130 is used to carry the first substrate S1. Specifically, the lower cavity 110 can be fixed to a base, and the upper cavity 120 is connected to a lifting device. By raising or lowering the upper chamber 120 through the lifting device, the upper chamber 120 can be separated from the lower chamber 100 to open the vacuum chamber 100a, or the upper chamber 120 can be combined with the lower chamber 110 to form the vacuum chamber 100a and the closed chamber 100b.

[0028] like Figure 1 , Figure 2 and Figure 3 As shown, the bonding head 140 is movably disposed on the upper cavity 120 of the vacuum cavity 100a, so that the bonding head 140 is movably disposed on the top of the vacuum cavity 100a, and the bonding head 140 is located in the closed chamber 100b. The bonding head 140 is correspondingly disposed above the carrier 130, and is used to apply pressure to the second substrate S2 to press the second substrate S2 onto the first substrate S1, so that the adhesive G between the two can fully bond the second substrate S2 to the first substrate S1, and exhaust the air between the first substrate S1 and the second substrate S2.

[0029] like Figure 1 , Figure 2 and Figure 3 As shown, specifically, the board bonding machine 100 further includes a linear actuator 180, which is disposed outside the upper cavity 120, and an actuating rod 182 of the linear actuator 180 passes through the upper cavity 120 and is connected to the bonding head 140 to drive the bonding head 140 to move toward the carrier 130 or away from the carrier 130. An airtight shaft seal is disposed at the joint of the actuating rod 182 and the upper cavity 120 to maintain the airtightness of the closed chamber 100b.

[0030] like Figure 1 , Figure 2 and Figure 3As shown, the exhaust pipe 150 is disposed in the vacuum chamber 100a, and is used to connect the sealed chamber 100b to the vacuum pump 190. The vacuum pump 190 is used to exhaust the sealed chamber 100b to reduce the air pressure of the sealed chamber 100b to a low pressure close to vacuum. Specifically, the exhaust pipe 150 can be disposed in the lower chamber 110 or in the upper chamber 120.

[0031] like Figure 1 , Figure 2 and Figure 3 As shown, the air inlet pipeline 160 is disposed in the vacuum chamber 100a, and is used to connect the sealed chamber 100b with the outside of the vacuum chamber 100a. Similarly, the air inlet pipeline 160 can be disposed in the lower chamber 110 or the upper chamber 120.

[0032] like Figure 1 , Figure 2 and Figure 3 As shown, the two-stage valve assembly 170 is connected to the air intake line 160 and communicated with the closed chamber 100b. The flow coefficient Cv (flow coefficient) of the two-stage valve assembly 170 can be switched between a first flow coefficient Cv1 and a second flow coefficient Cv2, and the second flow coefficient Cv2 is greater than the first flow coefficient Cv1. The two-stage valve assembly 170 is used to allow the gas from the external atmosphere to enter the closed chamber 100b to increase the pressure of the closed chamber 100b. When the two-stage valve assembly 170 is opened and switched to the first flow coefficient Cv1, the pressure inside the closed chamber 100b can be slowly increased; when the two-stage valve assembly 170 is opened and switched to the second flow coefficient Cv2, the pressure inside the closed chamber 100b is quickly increased to reach a balance with the external atmosphere.

[0033] like Figure 1 , Figure 2 and Figure 3As shown, the two-stage valve assembly 170 includes a first opening and closing valve 171, a throttle valve 173 and a second opening and closing valve 172. The first opening and closing valve 171 and the throttle valve 173 are connected in series to the intake pipe 160, and the first opening and closing valve 171 is located between the intake pipe 160 and the throttle valve 173. The two ends of the second opening and closing valve 172 are respectively connected to the inlet end of the first opening and closing valve 171 and the outlet end of the throttle valve 173, that is, the second opening and closing valve 172 bypasses the inlet end of the first opening and closing valve 171 to the outlet end of the throttle valve 173. The first opening and closing valve 171 and the second opening and closing valve 172 can be the same opening and closing valve, having the same fluid coefficient Cv. The throttle valve 173 can be used to adjust the gas flow through the second opening and closing valve 172. The throttle valve 173 can be adjusted in advance to a certain degree of opening and closing, so that the fluid coefficient Cv formed by the first opening and closing valve 171 and the throttle valve 173 connected in series is equal to the required first fluid coefficient Cv1. When the first opening and closing valve 171 and the second opening and closing valve 172 are opened at the same time, the two-stage valve assembly 170 has an equivalent second fluid coefficient Cv2, and the second fluid coefficient Cv2 is greater than the first fluid coefficient Cv1.

[0034] See also Figure 4 As shown, a plate bonding method provided by an embodiment of the present invention is shown.

[0035] like Figure 1 , Figure 2 and Figure 4 As shown, first, the first substrate S1 is disposed in the sealed chamber 100b. The first substrate S1 is first disposed on the carrying surface 132 of the carrying platform 130, and the carrying platform 132 is disposed at the bottom of the vacuum chamber 100a, as shown in step S110.

[0036] The first substrate S1 can be placed in the semi-open sealed chamber 100b when the sealed chamber 100b is not yet completely sealed, that is, when the upper cavity 120 and the lower cavity 100 are not yet combined, and is set on the carrying surface 132 of the carrier 130. The first substrate S1 and the second substrate S2 can also be placed in the semi-open sealed chamber 100b first, and the first substrate S1 and the second substrate S2 are first grasped by a clamp and a transfer tool (not shown). Then the upper cavity 120 and the lower cavity 100 are combined to form a closed sealed chamber 100b. Then the first substrate S1 is placed on the carrying surface 132 of the carrier 130 by a clamp and a transfer tool. This method can also be to place the first substrate S1 on the carrying surface 132 of the carrier 130 when the sealed chamber 100b is semi-open.

[0037] like Figure 2 and Figure 4As shown, the sealed chamber 100b is made airtight, for example, the upper chamber 120 and the lower chamber 110 are combined, and the vacuum pump 190 is used to evacuate the sealed chamber 100b to reduce the air pressure of the sealed chamber 100b to a predetermined low pressure value, such as a low pressure close to vacuum, as shown in step S120.

[0038] like Figure 3 and Figure 4 As shown, the second substrate S2 is placed on the first substrate S1, as shown in step S130. An adhesive G may be applied in advance on one of the first substrate S1 and the second substrate S2, so that the adhesive G is located between the first substrate S1 and the second substrate S2; the adhesive G may be pre-set on the upper surface of the first substrate S1, or on the lower surface of the second substrate S2.

[0039] In order to avoid large-area bubbles being formed directly when the second substrate S2 is placed on the first substrate S1, the second substrate S2 may be placed on the first substrate S1 at an angle and then gradually attached to the first substrate S1 so that large bubbles can be slowly discharged.

[0040] like Figure 3 , Figure 4 and Figure 5 As shown, when the closed chamber 100a is in a low pressure state, the linear actuator 180 is started to move the bonding head 140 toward the carrier 130 to contact the second substrate S2 and apply pressure to the second substrate S2 to press the second substrate S2 onto the first substrate S1 to form a bonding substrate, as shown in step S140.

[0041] like Figure 5 As shown, at this time, due to the low pressure suction of the sealed chamber 100b, the bubbles remaining on the adhesive G, that is, the bubbles between the first substrate S1 and the second substrate S2, will continue to move toward the edge of the bonding substrate, so that the gas between the first substrate S1 and the second substrate S2 is discharged. Therefore, the first substrate S1 and the second substrate S2 can form a good bond through the adhesive G, avoiding discontinuity in the bonding of the adhesive G.

[0042] like Figure 4 and Figure 6 As shown, then, the first opening and closing valve 171 is opened to allow the gas from the outside atmosphere to pass through the throttle valve 173 of the two-stage valve assembly 170 and the first opening and closing valve 171, and slowly enter the closed chamber 100b with the first fluid coefficient Cv1, so that the air pressure in the closed chamber 100b slowly rises, as shown in step S150.

[0043] At this time, the sealed chamber 100b still maintains a relatively low pressure state. Therefore, if there are still bubbles B between the first substrate S1 and the second substrate S2, the bubbles B can still be sucked out by the low pressure. The slow increase in air pressure also prevents the gas from re-entering the space between the first substrate S1 and the second substrate S2 to generate new bubbles B.

[0044] like Figure 4 and Figure 7 As shown, after a certain pressure increase time, the pressure inside the sealed chamber 100b reaches a certain ratio with the external atmospheric pressure, and the second opening and closing valve 172 is opened, so that the gas from the external atmosphere also enters the sealed chamber 100b through the second opening and closing valve 172. At this time, the gas from the external atmosphere passes through the first opening and closing valve 171, the second opening and closing valve 172 and the throttle valve 173 of the two-stage valve assembly 170, and quickly enters the sealed chamber 100b with the second fluid coefficient Cv2, so that the air pressure in the sealed chamber 100b rises quickly and reaches equilibrium with the external atmospheric pressure, as shown in step S160.

[0045] Finally, the linear actuator 180 drives the bonding head 140 to detach from the second substrate S2, separates the upper cavity 120 and the lower cavity 110, and opens the vacuum cavity 100a, so as to take out the bonding substrate composed of the first substrate S1 and the second substrate S2, and complete the board bonding operation.

[0046] Through the board bonding method proposed in the present invention, the air between the two bonded substrates can be fully removed, and at the same time, it is prevented that the air re-enters between the two substrates during the pressure recovery process, thereby effectively improving the bonding yield.

[0047] The above is only one embodiment of the present invention and is not intended to limit the scope of the present invention. That is, all equivalent changes and modifications to the shape, structure, characteristics and spirit described in the claims of the present invention should be included in the scope of protection requested by the present invention.

Claims

1. A board bonding method for bonding a first substrate and a second substrate; the method comprising: Placing the first substrate on a carrier in a closed chamber; Pumping air out of the sealed chamber to reduce the air pressure in the sealed chamber to a predetermined low pressure value; placing the second substrate on the first substrate; Applying pressure to the second substrate to press the second substrate onto the first substrate; Allowing the gas from the outside atmosphere to slowly enter the closed chamber at a first fluid coefficient; as well as The gas from the external atmosphere is allowed to quickly enter the closed chamber at a second fluid coefficient; wherein the second fluid coefficient is greater than the first fluid coefficient.

2. The plate bonding method according to claim 1, characterized in that: The step of providing the sealed chamber includes providing a vacuum chamber, wherein the sealed chamber is formed inside the vacuum chamber.

3. The plate bonding method according to claim 2, characterized in that: The first substrate is firstly arranged on the carrying surface of the carrying platform. The carrying platform is arranged at the bottom of the vacuum chamber, and the carrying surface faces the top of the vacuum chamber.

4. The plate bonding method according to claim 1, characterized in that: The step of evacuating the sealed chamber includes connecting a vacuum pump to the sealed chamber through an evacuation pipeline, and evacuating the chamber with the vacuum pump.

5. The plate bonding method according to claim 2, characterized in that: The step of applying pressure to the second substrate includes movably disposing a bonding head on the top of the vacuum chamber, so that the bonding head moves toward the carrier platform to contact the second substrate.

6. The plate bonding method according to claim 1, characterized in that: The step of allowing the gas of the external atmosphere to flow in includes connecting the closed chamber with a two-stage valve assembly; wherein the fluid coefficient of the two-stage valve assembly can be switched between a first fluid coefficient and a second fluid coefficient, and the second fluid coefficient is greater than the first fluid coefficient.

7. The plate bonding method according to claim 6, characterized in that: The two-stage valve assembly comprises: A first opening and closing valve and a throttle valve are connected in series to the intake pipeline, and the first opening and closing valve is located between the intake pipeline and the throttle valve, and a flow coefficient formed by the first opening and closing valve and the throttle valve being connected in series is equal to the first flow coefficient; and The second on-off valve has two ends connected to the inlet end of the first on-off valve and the outlet end of the throttle valve respectively, and when the first on-off valve and the second on-off valve are opened at the same time, the two-stage valve assembly has the second fluid coefficient.

8. The plate bonding method according to claim 7, characterized in that: The step of allowing the gas from the outside atmosphere to slowly enter the closed chamber at the first fluid coefficient includes: opening the first on-off valve to allow the gas from the outside atmosphere to enter the closed chamber through the throttle valve and the first on-off valve.

9. The plate bonding method according to claim 7, characterized in that: The step of allowing the gas from the outside atmosphere to quickly enter the closed chamber at the second fluid coefficient includes: opening the second on-off valve to allow the gas from the outside atmosphere to enter the closed chamber through the first on-off valve, the second on-off valve and the throttle valve at the same time.

10. The plate bonding method according to claim 7, characterized in that: The method further includes coating an adhesive on the first substrate or the second substrate so that the adhesive is located between the first substrate and the second substrate.

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