Wafer bonding machine plasma surface treatment device and method

Abstract

The invention discloses a wafer bonding machine plasma surface treatment device and method, and the method comprises the steps: 1, closing a second cabin door, opening a first cabin door, placing a to-be-treated wafer in a buffer chamber, then closing the first cabin door, and carrying out the vacuum pumping of the interior of the buffer chamber; step 2, opening a second cabin door, transferring the to-be-processed wafer in the buffer chamber into the main cabin, then closing the second cabin door, and vacuumizing the main cabin; 3, plasma surface treatment is completed on the wafer to be treated in the main chamber; 4, a second cabin door is opened, the processed wafer in the main cabin is transferred into the buffer chamber, and then the second cabin door is closed; and 5, opening the first cabin door, and taking out the processed wafer in the buffer chamber. In the whole processing process, the main cabin is not communicated with the external space and is always in a vacuumized negative pressure state, so that the working efficiency is improved, and the yield of wafer bonding can be effectively improved.

Description

Technical field:

[0001] The present invention relates to the technical field of wafer processing methods, and in particular to a wafer bonding machine plasma surface processing device and method for improving the yield rate of wafer bonding. Background technology:

[0002] Low-temperature wafer direct bonding technology is the most popular bonding method in recent years, but it is also very difficult. This is because it is the bonding method with the highest requirements for silicon wafer surface morphology and surface treatment process. Poor silicon wafer surface morphology or surface treatment will cause irreparable defects in the bonded wafer pair. The process of wafer direct bonding has gone through the process from early high-temperature wafer bonding to the currently widely studied and promoted low-temperature wafer bonding process, mainly to overcome the impact of high temperature on devices, so people began to focus on the research of low-temperature wafer bonding. The main research currently includes hydrophilic bonding and hydrophobic bonding. The essence of low-temperature direct bonding is to improve the surface energy by surface treatment of the silicon surface, and then bond two or more silicon wafers together through water molecule bridging (hydrophilic bonding) or HF molecule bridging (hydrophobic bonding) and intermolecular forces.

[0003] In low-temperature wafer direct bonding technology, surface treatment is one of the important processes. It is an important process related to the quality of bonding. The current surface treatment is mainly plasma surface treatment. The unbonded wafer will be placed in a high vacuum plasma chamber for surface activation to increase the density of hydroxyl (OH-) groups per unit surface area, thereby improving the quality of wafer bonding.

[0004] See Figure 1 As shown, this is a schematic diagram of the structure of the plasma surface treatment chamber in the existing conventional wafer bonding machine. The plasma surface treatment chamber 1 has a chamber 11. During operation, the chamber 11 is first opened, and the untreated wafer 4 is sent to the chamber 11 by a conveying device such as a robot, and then the chamber 11 is closed, and the chamber is evacuated to perform wafer plasma surface treatment. After completion, the chamber 11 destroys the internal vacuum, and then the chamber 11 is opened, and the bonded wafer 4 is moved out by the conveying device. This method will have the following problems:

[0005] First, it takes too long to pump the chamber from atmospheric pressure to vacuum, which results in a long process for each wafer plasma surface treatment, resulting in low production efficiency.

[0006] Secondly, the cabin needs to be opened continuously every time it is working, causing the chamber inside the cabin to be connected with the external space, resulting in external dust and other tiny particles entering the cabin, which may eventually cause the wafer bonding to fail, resulting in a low wafer bonding yield;

[0007] Finally, the frequent conversion of the cabin from vacuum to atmospheric pressure will cause irreversible damage to the internal components of the cabin, greatly reducing the service life of the equipment.

[0008] See the Chinese invention patent with patent document number CN117316837 B, which discloses "method, system and equipment for establishing a hybrid bonding continuity simulation model", and the technical solution adopted is: the wafer hybrid bonding vacuum interconnection equipment includes a first vacuum chamber, in which a plurality of first chambers are arranged; a second vacuum chamber, whose vacuum degree is higher than that of the first vacuum chamber and in which a plurality of second chambers are arranged; a buffer chamber, which is connected between the first vacuum chamber and the second vacuum chamber; a transfer device, which is arranged in the vacuum interconnection equipment and transfers the wafer and the core grain between the chambers; wherein the first chamber and the second chamber are sequentially installed with equipment and instruments of the corresponding processes according to the sequence of each process of the wafer hybrid bonding process. It can be seen from its technical solution that it directly sets up two chambers, and detection, cleaning, detection, etc. are arranged in the first chamber. Polishing, deposition, cutting, surface treatment, bonding, etc. are all arranged in the second chamber. The first chamber and the second chamber are connected through the buffer chamber, and the entire equipment is transferred in a vacuum interconnection device. Although this method is beneficial to wafer plasma surface treatment and wafer bonding, its manufacturing cost is too high and the manufacturing difficulty is too great.

[0009] In view of this, the inventor proposes the following technical solution in combination with the deficiencies in the prior art. Summary of the invention:

[0010] The technical problem to be solved by the present invention is to overcome the deficiencies of the prior art and to propose a wafer bonding machine plasma surface treatment device and method to improve the yield rate of wafer bonding.

[0011] In order to solve the above technical problems, the present invention adopts the following technical solutions: a plasma surface treatment device for a wafer bonding machine, comprising a main chamber for performing plasma surface treatment on wafers, a buffer chamber is arranged above the main chamber, and the buffer chamber is connected to the external space through a first chamber door; a second chamber door is arranged between the buffer chamber and the main chamber; a transfer mechanism for grabbing and moving wafers is arranged in the buffer chamber; the buffer chamber and the main chamber are both connected to a vacuum pumping device, and the buffer chamber and the main chamber are vacuumed by the vacuum pumping device.

[0012] Furthermore, in the above technical solution, a heating unit is provided in the buffer chamber.

[0013] Furthermore, in the above technical scheme, the plasma surface treatment method of the wafer bonding machine includes the following steps: Step 1: Close the second cabin door, open the first cabin door, place the wafer to be processed in the buffer chamber, and then close the first cabin door, and then vacuum the buffer chamber by a vacuum pumping device; Step 2: Open the second cabin door, transfer the wafer to be processed in the buffer chamber to the main cabin by a transfer mechanism, and then close the second cabin door, and vacuum the main cabin by a vacuum pumping device; Step 3: The wafer to be processed completes the plasma surface treatment in the main cabin; Step 4: Open the second cabin door, transfer the processed wafer in the main cabin to the buffer chamber by a transfer mechanism, and then close the second cabin door; Step 5: Open the first cabin door and take out the processed wafer in the buffer chamber; During the entire processing process, the main cabin is not connected to the external space and is always in a vacuum negative pressure state.

[0014] Furthermore, in the above technical solution, in the step 1, the buffer chamber is evacuated by a vacuum pumping device so that the vacuum degree in the buffer chamber reaches P1; in the step 2, the main chamber is evacuated by a vacuum pumping device so that the vacuum degree in the main chamber reaches P2; and P1 is less than or equal to P2.

[0015] Furthermore, in the above technical solution, the wafers to be processed are placed in the buffer chamber, and the processed wafers are taken out of the buffer chamber by a robotic arm.

[0016] Furthermore, in the above technical solution, a heating unit is provided in the buffer chamber; in the step 1, the untreated wafer surface is heated by the heating unit to remove water molecules on the wafer surface; in the step 4, the wafer that has undergone plasma surface treatment is annealed.

[0017] After adopting the above technical solution, the present invention has the following beneficial effects compared with the prior art:

[0018] Firstly, compared with the prior art, the present invention directly sets a buffer chamber above the main chamber of plasma surface treatment. Through the opening and closing of the first and second chamber doors, during the entire treatment process, the main chamber will not be connected to the external space and will always be in a vacuum negative pressure state. This can greatly improve the cleanliness inside the main chamber, reduce the entry of external particles, and improve the yield rate of wafer bonding.

[0019] Secondly, the main chamber of the present invention is always in a vacuum negative pressure state. Compared with the prior art, the time for vacuuming the main chamber after placing the wafer each time is greatly shortened, which greatly improves the work efficiency.

[0020] Finally, the main compartment of the present invention is always in a vacuum negative pressure state. Compared with the prior art in which the main compartment is frequently converted from vacuum to normal air pressure, the present invention can greatly reduce the damage to the components in the main compartment and increase the service life of the product. Description of the drawings:

[0021] Figure 1 It is a working principle diagram of the existing plasma surface treatment chamber;

[0022] Figure 2 It is a working principle diagram of the plasma surface treatment of the present invention;

[0023] Figure 3 is a schematic diagram of a first embodiment of a plasma surface treatment device in the present invention;

[0024] Figure 4 It is a schematic diagram of the second embodiment of the plasma surface treatment device in the present invention. Specific implementation method:

[0025] The present invention is further described below in conjunction with specific embodiments and drawings.

[0026] The present invention relates to a wafer bonding machine plasma surface treatment device and method. Figure 2 As shown, the plasma surface treatment device of the present invention is the same as the prior art, and it also has a main chamber 30 for performing plasma surface treatment on wafers. The difference from the prior art is that the present invention is provided with a buffer chamber 20 above the main chamber 30. When the wafer 4 to be processed needs to be subjected to plasma surface treatment, it needs to be placed in the buffer chamber 20 first, and then transferred from the buffer chamber 20 to the main chamber 30 for treatment. The volume of the buffer chamber 20 is smaller than that of the main chamber 30. Generally, the volume of the buffer chamber 20 is less than half of the volume of the main chamber 30, so that the processing time of evacuating the buffer chamber 20 can be shortened.

[0027] Specifically, the buffer chamber 20 is connected to the external space through the first hatch 21; a second hatch 31 is provided between the buffer chamber 20 and the main cabin 30. In addition, the buffer chamber 20 and the main cabin 30 are both connected to a vacuum pumping device, and the buffer chamber 20 and the main cabin 30 are vacuumed by the vacuum pumping device. The vacuum pumping device can be one, and the buffer chamber 20 and the main cabin 30 are vacuumed through the pipeline, or two, and the buffer chamber 20 and the main cabin 30 are vacuumed.

[0028] Since the wafer needs to be transferred from the buffer chamber 20 to the main chamber 30, a transfer mechanism for grabbing and moving the wafer needs to be provided in the buffer chamber 20. Figure 3As shown, the transfer mechanism 5 can be a robot or a suction cup mechanism with a telescopic arm. When the wafer to be processed is sent into the buffer chamber 20, the robot or the suction cup mechanism grabs the wafer to be processed. Then, the telescopic arm extends downward to pass the wafer to be processed through the second cabin door and is placed on the processing workbench in the main cabin 30.

[0029] Combination Figure 2 As shown, the plasma surface treatment method for a wafer bonding machine of the present invention comprises the following steps:

[0030] Step 1: close the second hatch 31, open the first hatch 21, place the wafer 4 to be processed in the buffer chamber 20, and then close the first hatch 21, and then vacuum the buffer chamber 20 through a vacuum device.

[0031] When the first hatch 21 is opened, the buffer chamber 20 is connected to the external environment. The robotic arm in the wafer bonding machine will grab the wafer removed from the previous station and place it in the buffer chamber 20. After the wafer is sent into the buffer chamber 20, the wafer is grabbed by the transfer mechanism in the buffer chamber 20. After the robotic arm in the wafer bonding machine withdraws, the first hatch 21 is closed. At this time, a closed space is formed in the buffer chamber 20, and the buffer chamber 20 is vacuumed by a vacuum pumping device. The vacuum degree in the buffer chamber 20 reaches P1, so that the particles that may enter the buffer chamber 20 are removed. At this time, the buffer chamber 20 is in a medium-low vacuum environment.

[0032] Step 2: Open the second hatch 31, transfer the wafer 4 to be processed in the buffer chamber 20 to the main chamber 30 through the transfer mechanism, and place it on the workbench of the main chamber 30. The transfer mechanism is retracted into the buffer chamber 20, and the second hatch 31 is closed. Since the main chamber 30 is connected to the buffer chamber 20, the original high vacuum degree of the main chamber is destroyed. At the same time, in order to further remove the particles that may enter, the main chamber 30 is vacuumed by the vacuum device, so that the vacuum degree in the main chamber 30 reaches P2 (P1 is less than or equal to P2), which is in a high vacuum state.

[0033] Step 3: After the environment in the main chamber 30 is in a high vacuum state, turn on the equipment and perform plasma surface treatment on the wafer. The unbonded wafer will be surface activated in the high vacuum main chamber 30 to increase the density of hydroxyl (OH-) groups per unit surface area.

[0034] Step 4: After the wafer has completed the plasma surface treatment, the second hatch 31 is opened, and the buffer chamber 20 is connected to the main chamber 30 again. The processed wafer 4 in the main chamber 30 is transferred to the buffer chamber 20 by the transfer device in the buffer chamber 20, and then the second hatch 31 is closed. At this time, the main chamber 30 enters a closed state again.

[0035] Step 5: Finally, open the first hatch 21 and take out the processed wafer 4 in the buffer chamber 20 through an external robotic arm, waiting to enter the next process of the wafer bonding machine for processing.

[0036] From the above description, during the entire process of plasma surface treatment of the wafer, the main chamber 30 is not connected to the external space and is always in a vacuum negative pressure state, so that the main chamber is always maintained in the best state, thereby improving the yield of wafer bonding. At the same time, it can effectively reduce plasma anomalies and further improve the yield of wafer bonding.

[0037] In addition, since the main chamber 30 of the present invention is always in a vacuum state, compared with the prior art, the time for vacuuming the main chamber after each wafer is placed is greatly shortened, which greatly improves the work efficiency. In view of this, the present invention can be combined with an oven to simultaneously complete the heating, baking and annealing of the wafer. Figure 2 As shown, this is the second embodiment of the present invention, in which a heating unit 22 is provided in the buffer chamber 20. The wafer that has not been subjected to plasma surface treatment is heated by the heating unit 22. That is, before the wafer is subjected to plasma surface treatment, heating and degassing treatment is performed by the heating unit 22. High temperature can make the deep water molecules on the surface of the wafer be removed more cleanly, which can improve the effect of the subsequent plasma surface treatment. At the same time, after the wafer is subjected to plasma surface treatment, the heating unit 22 can perform bonding annealing treatment on the wafer.

[0038] In the existing wafer bonding machine, a baking chamber is usually specially set up to heat and anneal the wafer. The present invention is directly combined in the buffer chamber 20, which can greatly reduce the cost of the product and effectively improve the tea production efficiency.

[0039] Of course, the above description is only a specific embodiment of the present invention and is not intended to limit the scope of implementation of the present invention. All equivalent changes or modifications made according to the structure, characteristics and principles described in the patent application scope of the present invention should be included in the patent application scope of the present invention.

Claims

1. A plasma surface treatment device for a wafer bonding machine, comprising a main chamber (30) for performing plasma surface treatment on a wafer, characterized in that: A buffer chamber (20) is arranged above the main chamber (30), and the buffer chamber (20) is connected to the external space through a first chamber door (21); a second chamber door (31) is arranged between the buffer chamber (20) and the main chamber (30); and a transfer mechanism for grabbing and moving wafers is arranged in the buffer chamber (20); The buffer chamber (20) and the main chamber (30) are both connected to a vacuum pumping device, and the buffer chamber (20) and the main chamber (30) are vacuumed by the vacuum pumping device.

2. The wafer bonding machine plasma surface treatment device according to claim 1, characterized in that: A heating unit (22) is arranged in the buffer chamber (20).

3. The wafer bonding machine plasma surface treatment device according to claim 1 or 2, characterized in that: The plasma surface treatment method for wafer bonding machine includes the following steps: Step 1: closing the second hatch (31), opening the first hatch (21), placing the wafer (4) to be processed in the buffer chamber (20), and then closing the first hatch (21) and performing vacuum treatment on the buffer chamber (20) by using a vacuum device; Step 2: Open the second hatch (31), transfer the wafer (4) to be processed in the buffer chamber (20) to the main chamber (30) through the transfer mechanism, then close the second hatch (31), and perform vacuum treatment on the main chamber (30) through the vacuum device; Step 3: The wafer to be processed (4) is subjected to plasma surface treatment in the main chamber (30); Step 4: Open the second hatch (31), transfer the processed wafer (4) in the main chamber (30) to the buffer chamber (20) through the transfer mechanism, and then close the second hatch (31); Step 5: Open the first hatch (21) and take out the processed wafer (4) in the buffer chamber (20); During the entire treatment process, the main chamber (30) is not connected to the external space and is always in a vacuum negative pressure state.

4. The plasma surface treatment device for wafer bonding machine according to claim 3, characterized in that: In the step 1, the buffer chamber (20) is evacuated by a vacuum pumping device, so that the vacuum degree in the buffer chamber (20) reaches P1; in the step 2, the main chamber (30) is evacuated by a vacuum pumping device, so that the vacuum degree in the main chamber (30) reaches P2; The P1 is less than or equal to P2.

5. The plasma surface treatment device for wafer bonding machine according to claim 3, characterized in that: The wafer (4) to be processed is placed in the buffer chamber (20), and the processed wafer (4) is taken out of the buffer chamber (20) by a robot arm.

6. The plasma surface treatment device for wafer bonding machine according to claim 3, characterized in that: The buffer chamber (20) is provided with a heating unit (22); in the step 1, the untreated wafer surface is heated by the heating unit (22) to remove water molecules on the wafer surface; in the step 4, the wafer that has undergone plasma surface treatment is annealed.

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