Multilayer chip flip stacking and bonding device and technology assisted by ultrasonic technology

Abstract

The invention relates to the field of multi-layer chip stacking and bonding, in particular to an ultrasonic process-assisted multi-layer chip flip stacking and bonding device and process, which comprises the following steps of: 1, driving a vacuum stacking suction head mechanism to move through a longitudinal displacement table and a transverse displacement table, enabling the vacuum stacking suction head mechanism to clamp, stack and place the chips on the heating bonding table; 2, enabling an ultrasonic bonding head mechanism to move to the stacked chips through a longitudinal displacement table and a transverse displacement table, and immediately stopping after the lower part of the ultrasonic bonding head mechanism is in slow contact with the to-be-bonded chips; and 3, starting the heating bonding table to heat the stacked chips, after a specified temperature value is reached, controlling the ultrasonic bonding head mechanism to apply 40-60MPa bonding pre-pressure through the longitudinal displacement table, stopping moving, and then starting the ultrasonic bonding head mechanism to carry out bonding.

Description

Technical Field

[0001] The invention relates to the field of multi-layer chip stacking and bonding, and more specifically to an ultrasonic process-assisted multi-layer chip flip-chip stacking and bonding device and process. Background Art

[0002] Flip-chip bonding is an advanced microelectronic packaging technology that is mainly used to connect semiconductor chips to packaging substrates or printed circuit boards. In flip-chip bonding, the active side of the chip containing the circuit faces the substrate, and the pads on the chip are directly connected to the corresponding solder joints on the substrate, usually through solder balls or pillars. Compared with traditional wire bonding, flip-chip bonding technology provides higher I / O density and shorter interconnection paths, which can achieve faster data transmission speeds and smaller package sizes. Multi-layer chip flip-chip bonding is an extension of flip-chip bonding technology, involving stacking multiple chips together to achieve higher integration and more complex functions. Traditional multi-layer chip packaging generally adopts a process flow of alternating cycles of stacking and bonding layer by layer. Under the action of thermal cycles and mechanical stress, flip-chip bonding may cause cracks or fatigue in chips and bonding materials, affecting the reliability and life of the product. When bonding the top chip, the bottom chip will be subjected to thermal cycles and mechanical stress many times, resulting in a much higher probability of cracks and damage than the upper layer chips and uneven bonding quality between layers. As the number of chip layers increases, the overall bonding time of multi-layer chips increases linearly, the packaging bonding efficiency is too low, and the welded parts are repeatedly squeezed. The finished chip is prone to cold solder joints, internal voids in solder joints, and poor coplanarity of chip bumps. In addition, multiple heating and welding processes waste time and resources. When this method is used in the production of multi-layer flip chips, it is difficult to ensure the reliability and yield of the product structure. In addition, the thermal cycle process has the problem of too low energy transmission efficiency for multi-layer chip bonding due to too many transmission interface layers, inconsistent thermal cycle effects between the middle and outer layers of the chip, and the outermost chip is subjected to the highest thermal and mechanical energy and is most susceptible to damage, affecting the overall bonding quality.

[0003] In order to improve the yield rate of multi-layer chip bonding and optimize the multi-layer chip bonding environment, it is impossible to rely on traditional thermal compression flip-chip bonding. Therefore, a bonding device that optimizes the multi-layer chip flip-chip bonding process and integrates chip stacking and bonding is needed. Summary of the invention

[0004] The purpose of the present invention is to provide an ultrasonic process-assisted multi-layer chip flip-chip stacking and bonding device and process to solve the problem that multiple bonding operations on multi-layer chips using traditional hot pressing processes in multi-layer chip bonding cause the solder joints between chip layers to be damaged and fail due to multiple extrusions and heat.

[0005] The purpose of the present invention is achieved through the following technical solutions:

[0006] A multi-layer chip flip-chip stacking and bonding device assisted by an ultrasonic process comprises a heated bonding platform, a lateral displacement platform and a horizontal turntable are installed on the side of the heated bonding platform, a longitudinal displacement platform is installed on the movable end of the lateral displacement platform, a vacuum stacking suction head mechanism and an ultrasonic bonding head mechanism are installed on the movable end of the longitudinal displacement platform, and an alignment monitor is installed on the horizontal turntable;

[0007] The longitudinal translation stage has an accuracy of ±1 micron and a travel of 200 mm;

[0008] The lateral translation stage has an accuracy of ±10 microns and a travel range of 150 mm;

[0009] The alignment monitor includes an industrial camera and a spectroscopic prism;

[0010] The vacuum stacking suction head mechanism comprises a stacking suction head capable of clamping and placing the chip, and the stacking suction head is connected to an air pipe providing vacuum suction;

[0011] The ultrasonic bonding head mechanism includes a bonding head and a longitudinal vibration ultrasonic transducer connected above the bonding head, the longitudinal vibration ultrasonic transducer is connected to the ultrasonic driver, and the ultrasonic power range of the longitudinal vibration ultrasonic transducer is 50-100W;

[0012] The heating temperature range of the heating bonding station is 30-300°C. The working surface of the heating bonding station heats and welds the chip by pulse heating, completing the bonding of each layer of the chip at one time.

[0013] The surface of the heating bonding platform is provided with a temperature-resistant and flexible material to prevent the high-frequency vibration caused by the longitudinal ultrasonic transducer from causing fatigue damage to the chip;

[0014] An ultrasonic process-assisted multi-layer chip flip-chip stacking and bonding process, the process comprising the following steps:

[0015] Step 1: The vacuum stacking suction head mechanism is driven to move by the longitudinal translation stage and the transverse translation stage, so that the vacuum stacking suction head mechanism clamps and stacks the chips and places them on the heated bonding table;

[0016] Step 2: The ultrasonic bonding head mechanism is moved onto the stacked chips through the longitudinal displacement stage and the transverse displacement stage, and the bottom of the ultrasonic bonding head mechanism slowly contacts the chip to be bonded and then stops immediately;

[0017] Step 3: Start the heating bonding stage to heat the stacked chips. After reaching the specified temperature, control the ultrasonic bonding head mechanism to apply a bonding pre-pressure of 40-60MPa through the longitudinal translation stage, stop moving, and then start the ultrasonic bonding head mechanism for bonding;

[0018] In the step one, the vacuum stacking suction head mechanism is finely adjusted by the alignment monitor, and in the step two, the ultrasonic bonding head mechanism is finely adjusted by the alignment monitor.

[0019] The beneficial effects of the present invention are:

[0020] Through the ultrasonic process, the temperature and pressure of the chip are reduced, and the process parameters of ultrasonic bonding are improved. Compared with the working environment of traditional hot-press flip-chip bonding, the chip breakage and chip interlayer solder joint damage caused by high temperature and high pressure during the bonding process are reduced, and the yield rate of multi-layer chip bonding is improved. High-power density longitudinal vibration ultrasound is used as the auxiliary bonding energy source, and its energy transfer efficiency is higher. At the same time, the inter-chip slippage caused by transverse vibration ultrasonic auxiliary bonding is avoided, and the adaptability to the multi-layer chip bonding process is improved;

[0021] Through the device of multi-layer flip chip stacking and integrated bonding, it is possible to perform only one hot pressing process in the multi-layer chip bonding process, and with the optimization of process parameters assisted by new ultrasonic technology, it effectively improves the phenomenon of damage and failure of chip interlayer solder joints caused by repeated high temperature and high pressure. From the production point of view, only one hot processing and lowering the thermal energy threshold can reduce manufacturing costs, reduce working hours, and improve production efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The present invention is further described in detail below with reference to the accompanying drawings and specific implementation methods.

[0023] Figure 1 It is a schematic structural diagram of a multi-layer chip flip-chip stacking and bonding device assisted by an ultrasonic process of the present invention;

[0024] Figure 2 It is a schematic diagram of the structure of the horizontal turntable of the present invention;

[0025] Figure 3 It is a schematic diagram of the stacking and bonding switching operation of the present invention;

[0026] Figure 4 It is a schematic diagram of the ultrasonic process-assisted multi-layer chip flip-chip stacking and bonding process flow of the present invention.

[0027] In the figure: longitudinal displacement stage 1; vacuum stacking suction head mechanism 2; alignment monitor 3; lateral displacement stage 4; heating bonding stage 5; horizontal turntable 6; ultrasonic bonding head mechanism 7; chip to be stacked 8; and stacked chip 9. DETAILED DESCRIPTION

[0028] The present invention is further described in detail below with reference to the accompanying drawings.

[0029] like Figures 1 to 3As shown, the structure and function of an ultrasonic process-assisted multi-layer chip flip-chip stacking and bonding device are described in detail below;

[0030] A multi-layer chip flip-chip stacking and bonding device assisted by an ultrasonic process comprises a heating bonding platform 5, a lateral displacement platform 4 and a horizontal turntable 6 are installed on the side of the heating bonding platform 5, a longitudinal displacement platform 1 is installed on the movable end of the lateral displacement platform 4, a vacuum stacking suction head mechanism 2 and an ultrasonic bonding head mechanism 7 are installed on the movable end of the longitudinal displacement platform 1, and an alignment monitor 3 is installed on the horizontal turntable 6;

[0031] The longitudinal displacement stage 1 has an accuracy of ±1 micron and a travel range of 200 mm; it can achieve high-precision movement from micron level to centimeter level;

[0032] The lateral displacement stage 4 has an accuracy of ±10 microns and a travel range of 150 mm; it can achieve high-precision movement from micron level to centimeter level.

[0033] The alignment monitor 3 includes an industrial camera and a spectroscopic prism; the alignment monitor 3 is mainly responsible for real-time monitoring whether the position of chip stacking and bonding is accurate; the industrial camera and the spectroscopic prism are used to monitor and compare the positions of the stacked chips and the chips to be stacked in real time to observe whether the positions of the solder joints correspond and whether there is any deviation in the chip positions;

[0034] The vacuum stacking suction head mechanism 2 includes a stacking suction head capable of clamping and placing the chip, and the stacking suction head is connected to an air pipe providing vacuum suction;

[0035] The ultrasonic bonding head mechanism 7 includes a bonding head and a longitudinal vibration ultrasonic transducer connected above the bonding head. The longitudinal vibration ultrasonic transducer is connected to an ultrasonic driver and generates acoustic energy of a fixed frequency and power through the driver setting. To ensure the stability of ultrasonic energy release, the ultrasonic power range of the longitudinal vibration ultrasonic transducer is 50-100W; the ultrasonic bonding head mechanism 7 is mainly responsible for the bonding operation of multi-layer chips;

[0036] The heating temperature range of the heating bonding station 5 is 30-300°C. The working surface of the heating bonding station 5 heats and welds the chip by pulse heating, completing the bonding of each layer of chips at one time. The heating bonding station 5 is mainly responsible for receiving the stacked chip structure and cooperating with the bonding head to perform the bonding operation.

[0037] When in use, the vacuum stacking suction head mechanism 2 is used for suction and alignment, the air pipe connected to the stacking suction head provides vacuum suction to suck the chip to be stacked, and the stacked chip 9 and the chip to be stacked 8 are aligned through the alignment monitor 3; the stacked chip 9 is placed on the heating bonding table 5, and after the alignment is completed, the alignment monitor 3 is moved out of the working area through the horizontal turntable 6; the longitudinal displacement table 1 moves downward, and its moving distance is set. When it reaches the specified position, it slowly contacts the stacked chip 9 below and stops immediately. During the movement, it is determined at all times whether it is in contact. After contact, the stacking suction head stops suctioning, so that the chip is placed stably on the top layer. After that, it is determined whether the stacking of multiple layers of chips has been completed. If not, the longitudinal displacement table 1 is moved downward. Move the translation table upwards to clamp the next layer of chips to be stacked, and continue to repeat the above steps until the stacking of multiple layers of chips is completed; if the stacking is completed, move the ultrasonic bonding head mechanism 7 to the working area through the lateral translation table 4, start the longitudinal vibration ultrasonic transducer and driver, and set the ultrasonic parameters through the ultrasonic driver; then move the alignment monitor 3 to the bottom of the ultrasonic bonding head mechanism 7 for fine alignment adjustment. After the adjustment is completed, move the alignment monitor 3 out of the working area through the horizontal turntable 6; move downward through the longitudinal translation table 1, set its moving distance, and stop immediately after it reaches the specified position and slowly contacts the chip to be bonded below; finally, start the heating bonding table 5 for heating and set the heating temperature. After reaching the specified temperature value, control the ultrasonic bonding head mechanism 7 to move down to the specified distance accurately through the longitudinal translation table 1 to apply the bonding pre-pressure and stop moving. Then start the ultrasonic bonding head mechanism 7 for bonding. During the bonding process, observe the frequency and power values ​​of the ultrasonic driver in real time. If the value fluctuates significantly, turn off the ultrasonic device immediately to prevent the bonding head from colliding and being damaged by the bonding table. Stop heating after the bonding welding is completed;

[0038] like Figure 4 As shown, the steps and functions of an ultrasonic process-assisted multi-layer chip flip-chip stacking and bonding process are described in detail below;

[0039] An ultrasonic process-assisted multi-layer chip flip-chip stacking and bonding process, the process comprising the following steps:

[0040] Step 1: The vacuum stacking suction head mechanism 2 is driven to move by the longitudinal displacement stage 1 and the transverse displacement stage 4, so that the vacuum stacking suction head mechanism 2 clamps and stacks the chips and places them on the heating bonding stage 5; the stacked chips 9 are placed on the heating bonding stage 5, and then the chips to be stacked 8 are sucked and aligned by the vacuum stacking suction head mechanism 2, and the longitudinal displacement stage 1 and the transverse displacement stage 4 are controlled to move to the working area, and then the alignment monitor 3 is moved to the bottom of the vacuum stacking suction head mechanism 2 for fine alignment adjustment. After the adjustment is completed, the alignment monitor 3 is moved out of the working area by the horizontal turntable 6; the longitudinal displacement stage 1 moves downward, and its moving distance is set. When it reaches the specified position, it stops immediately after slowly contacting the stacked chips below; then the longitudinal displacement stage 1 moves upward, and then step 1 is repeated until the stacking of multiple layers of chips is completed;

[0041] Step 2: After the multi-layer chip stacking is completed, the ultrasonic bonding head mechanism 7 is moved to the working area through the lateral displacement stage 4, the longitudinal vibration ultrasonic transducer and the driver are started, and the ultrasonic parameters are set through the ultrasonic driver; then the alignment monitor 3 is moved to the bottom of the ultrasonic bonding head mechanism 7 for fine alignment adjustment, and after the adjustment is completed, the alignment monitor 3 is moved out of the working area through the horizontal turntable 6; the longitudinal displacement stage 1 is moved downward, and its moving distance is set, and when it reaches the specified position, it stops immediately after slowly contacting the chip to be bonded below;

[0042] Step 3: Start the heating bonding stage 5 to heat the stacked chips, set the heating temperature, and after reaching the specified temperature value, control the ultrasonic bonding head mechanism 7 through the longitudinal displacement stage 1 to move down to the specified distance with precision, apply a bonding pre-pressure of 40-60MPa, stop moving, and then start the ultrasonic bonding head mechanism 7 for bonding.

Claims

1. An ultrasonic process-assisted multi-layer chip flip-chip stacking and bonding device, comprising a heated bonding station (5), characterized in that: A lateral displacement stage (4) and a horizontal turntable (6) are installed on the side of the heating bonding stage (5); a longitudinal displacement stage (1) is installed on the movable end of the lateral displacement stage (4); a vacuum stacking suction head mechanism (2) and an ultrasonic bonding head mechanism (7) are installed on the movable end of the longitudinal displacement stage (1); and an alignment monitor (3) is installed on the horizontal turntable (6).

2. The ultrasonic process-assisted multi-layer chip flip-chip stacking and bonding device according to claim 1, characterized in that: The longitudinal displacement stage (1) has an accuracy of ±1 micron and a travel range of 200 millimeters.

3. The ultrasonic process-assisted multi-layer chip flip-chip stacking and bonding device according to claim 1, characterized in that: The lateral displacement stage (4) has an accuracy of ±10 microns and a travel range of 150 millimeters.

4. The ultrasonic process-assisted multi-layer chip flip-chip stacking and bonding device according to claim 1, characterized in that: The alignment monitor (3) comprises an industrial camera and a spectroscopic prism.

5. The ultrasonic process-assisted multi-layer chip flip-chip stacking and bonding device according to claim 1, characterized in that: The vacuum stacking suction head mechanism (2) comprises a stacking suction head capable of clamping and placing the chip, and the stacking suction head is connected to an air pipe that provides vacuum suction.

6. The ultrasonic process-assisted multi-layer chip flip-chip stacking and bonding device according to claim 1, characterized in that: The ultrasonic bonding head mechanism (7) comprises a bonding head and a longitudinal vibration ultrasonic transducer connected above the bonding head, and the longitudinal vibration ultrasonic transducer is connected to an ultrasonic driver.

7. The ultrasonic process-assisted multi-layer chip flip-chip stacking and bonding device according to claim 4, characterized in that: The ultrasonic power range of the longitudinal vibration ultrasonic transducer is 50-100W.

8. The ultrasonic process-assisted multi-layer chip flip-chip stacking and bonding device according to claim 1, characterized in that: The heating temperature range of the heating bonding platform (5) is 30-300° C. The working surface of the heating bonding platform (5) heats and welds the chip by pulse heating, thereby completing the bonding of each layer of the chip at one time.

9. An ultrasonic process-assisted multi-layer chip flip-chip stacking and bonding process, characterized in that: The process includes the following steps: Step 1: driving the vacuum stacking suction head mechanism (2) to move by means of the longitudinal displacement stage (1) and the transverse displacement stage (4), so that the vacuum stacking suction head mechanism (2) clamps and stacks the chips and places them on the heated bonding stage (5); Step 2: The ultrasonic bonding head mechanism (7) is moved onto the stacked chips by means of the longitudinal displacement stage (1) and the transverse displacement stage (4), and the ultrasonic bonding head mechanism (7) is stopped immediately after the bottom of the ultrasonic bonding head mechanism (7) slowly contacts the chip to be bonded; Step 3: Start the heating bonding stage (5) to heat the stacked chips. After reaching the specified temperature value, control the ultrasonic bonding head mechanism (7) through the longitudinal displacement stage (1) to apply a bonding pre-pressure of 40-60 MPa, stop moving, and then start the ultrasonic bonding head mechanism (7) for bonding.

10. The ultrasonic process-assisted multi-layer chip flip-chip stacking and bonding process according to claim 9, characterized in that: In the step one, the vacuum stacking suction head mechanism (2) is finely aligned and adjusted by the alignment monitor (3), and in the step two, the ultrasonic bonding head mechanism (7) is finely aligned and adjusted by the alignment monitor (3).

Images