CN110752177A - Reflective flip chip bonding machine and chip bonding method - Google Patents

Abstract

The invention discloses a reflective flip-chip bonding machine and a chip bonding method, which can improve alignment and bonding accuracy and reduce the complexity of chip technology. The reflective flip-chip bonding machine includes: an upper suction device for installing an upper chip; a lower suction device for installing a lower chip; a through hole arranged on the lower suction device; an infrared light emitting diode; A beam splitter arranged in the direction of the infrared light path; an objective lens connected to the outgoing light of the beam splitter and facing the through hole; an industrial camera connected to the reflected light of the beam splitter; a display connected to the industrial camera. The observation device of the present invention has a simple structure, does not need to insert other complex optical systems between two chips for observation, greatly reduces the manufacturing complexity and cost, and greatly reduces errors and improves the bonding accuracy.

Description

Reflective flip-chip bonding machine and chip bonding method

technical field

The invention relates to the technical field of chip bonding, in particular to a reflective flip-chip bonding machine and a chip bonding method.

Background technique

Chip bonding means that after cleaning two chips with devices, they are bonded together under certain conditions by a certain method (such as heating, applying pressure, etc.), so that the two chips are combined into a whole. A very important step is involved in this process - chip alignment. At present, the alignment of flip-chip bonding devices on the market is mostly to irradiate the upper and lower chips to be bonded with visible light, and measure the relative distance of the two chips through the alignment pattern on the chips, and move according to the relative distance. and align. In this method, two chips to be bonded need to be separated in the alignment stage, so that an observation device is inserted between the two chips, and after the observation is completed, the distance between the two chips is shortened and bonded.

In the existing technical solution, the two chips are respectively part of the marks of the two chips that need to be aligned. Inserting all-reflecting mirrors in the two chips makes the light return to the camera to obtain the chip marking pattern, and the subsequent alignment process is performed. Such a structure is complex and because the bonding process cannot be observed in real time, it is difficult to ensure that the horizontal distance between the two chips remains unchanged during the approaching process, and it is difficult to improve the accuracy. Since the flip-chip bonding machine needs to observe the alignment marks on the surface of the chip, the traditional bonding machine needs to turn the chip during observation to facilitate observation or insert an observation device into the two chips to be bonded. For example, systematic errors and displacement errors are increased.

SUMMARY OF THE INVENTION

The present invention provides a reflective flip-chip bonding machine and a chip bonding method, which can improve alignment and bonding precision and reduce the complexity of chip technology.

A reflective flip-chip bonding machine, comprising:

The upper adsorption device used to install the upper chip;

A lower adsorption device for installing the lower chip;

a through hole arranged on the lower adsorption device;

Infrared light-emitting diodes for emitting infrared light;

a beam splitter arranged along the direction of the infrared light path of the infrared light emitting diode;

an objective lens connected to the outgoing light of the beam splitter and facing the through hole;

an industrial camera docked with the reflected light from the beam splitter;

A display connected to the industrial camera.

In the present invention, the infrared light-emitting diode emits infrared light, which first passes through the beam splitter, then passes through the objective lens, and then passes through the through hole, and irradiates the surface of the chip. The reflected light passes through the objective lens, and the beam splitter is reflected to the industrial camera and transmitted through the data line As far as the display is concerned, the observation device has a simple structure, and does not need to insert other complex optical systems between the two chips for observation, which greatly reduces the manufacturing complexity and cost. Due to the special optical path design, the light penetrates the lower chip from below and irradiates the surface of the upper chip, so the upper chip does not need double-sided lithography and polishing, that is, there is no process requirement for the bottom of the upper chip, which reduces the process restrictions on the upper chip and The complexity of the process greatly expands the applicable objects of the equipment.

The upper chip and the lower chip are relative concepts, indicating that two chips are required for bonding, and the upper adsorption device and the lower adsorption device are also relatively changed, indicating that there are two oppositely arranged adsorption devices. It can also be written as, the first adsorption device for installing the first chip; the second adsorption device for installing the second chip.

The upper adsorption device and the lower adsorption device are arranged opposite to each other and cooperate with each other. That is to say, the first adsorption device and the second adsorption device are arranged opposite to each other and cooperate with each other.

The upper adsorption device is connected with a three-dimensional moving device, specifically a support frame of the upper adsorption device. The upper suction device can move with the movement of the horizontally and vertically movable support frame.

The lower adsorption device is connected with a three-dimensional moving device, specifically a lower adsorption device support frame. In the same way, the adsorption device can move with the movement of the horizontally and vertically movable support frame.

The lower adsorption device is connected with a temperature control device, which can provide a corresponding working temperature for chip bonding.

The through hole allows light to pass through, allowing the incidence of infrared light and the light emitted from the chip surface to pass through.

The beam splitter is used to allow the infrared light emitted by the infrared light-emitting diode to pass through smoothly and to split the reflected light to the industrial camera.

A reflector is arranged between the infrared light-emitting diode and the beam splitter. The infrared light-emitting diode emits infrared light, first through the reflector and beam splitter, then through the objective lens, and then through the through hole, irradiating the surface of the chip, the reflected light passes through the objective lens, the beam splitter is reflected to the industrial camera, and is transmitted to the monitor.

The reflection mirror adopts a 45° reflection structure, and the reflection mirror is arranged on the reflection mirror displacement stage.

The industrial camera is set on the industrial camera displacement stage.

A flip-chip bonding method, using the reflective flip-chip bonding machine of the present invention, includes the following steps:

Step 1: respectively fix the upper chip and the lower chip to be bonded with the upper adsorption device and the lower adsorption device;

Step 2: Adjust the upper adsorption device support frame and the lower adsorption device support frame so that the two chips are close to each other and the marking patterns on the two chips can be clearly seen on the display;

Step 3: Change the position of the upper chip according to the marking pattern, until the marking pattern of the upper chip and the marking pattern of the lower chip are aligned;

Step 4: Turn on the heating function of the temperature control device, adjust the support frame of the lower adsorption device so that the upper chip is pressed on the lower chip, and the bonding is completed.

Compared with the prior art, the present invention has the following advantages:

1. The structure of the observation device is simple, and there is no need to insert other complex optical systems between the two chips for observation, which greatly reduces the manufacturing complexity and cost.

2. Since the distance between the upper and lower chips during the alignment process is infinitely close, the integration of bonding and alignment can be achieved by using this special alignment method. Different from the traditional bonding machine that aligns first and then bonds, the present invention does not need to move the observation device and the large stroke displacement of the upper and lower chips, and can be directly bonded after alignment, realizing the synchronization of alignment and bonding. The error is greatly reduced and the bonding accuracy is improved.

3. Due to the special optical path design, the light penetrates the lower chip from below to irradiate the surface of the upper chip, so the upper chip does not need double-sided lithography, nor does it need to be polished, that is, there is no process requirement for the bottom of the upper chip, which reduces the process of the upper chip. Restrictions and process complexity greatly expand the applicable objects of the equipment.

Description of drawings

1 is a schematic structural diagram of a reflective flip-chip bonding machine of the present invention;

FIG. 2 is a schematic flowchart of the flip-chip bonding method of the present invention.

Detailed ways

As shown in FIG. 1 , a reflective flip-chip bonding machine includes: an upper adsorption device 1 for installing an upper chip 2; a lower adsorption device 4 for installing a lower chip 3 in cooperation with the upper adsorption device 1; The through hole 14 on the lower adsorption device 4; the infrared light emitting diode 10 for emitting infrared light; the beam splitter 8 for allowing the infrared light emitted by the infrared light emitting diode 10 to pass smoothly and reflecting the emitted light; and the beam splitter 8 The objective lens 7 which is connected and is arranged facing the through hole 14 ; the industrial camera 9 which is docked with the objective lens 7 ; the display 12 which is connected with the industrial camera 9 . The industrial camera 9 is arranged on the stage 15 . A reflector 11 is provided between the infrared light emitting diode 10 and the beam splitter 8 .

The upper adsorption device 1 is connected with a three-dimensional moving device, specifically a support frame 13 , and the upper adsorption device 1 can move with the movement of the horizontally and vertically movable support frame 13 .

The lower adsorption device 4 is connected with a three-dimensional moving device, specifically a support frame 6 . Similarly, the adsorption device 4 can move with the movement of the support frame 6 that can move horizontally and vertically.

The lower adsorption device 4 is connected with a temperature control device 5, which can provide a corresponding working temperature for chip bonding.

As shown in FIG. 1 , in the reflective flip-chip bonding machine, two chips to be bonded, the upper chip 2 and the lower chip 3 are respectively fixed by the upper adsorption device 1 and the lower adsorption device 4 . The lower adsorption device 4 is connected to the temperature control device 5, which can provide a corresponding working temperature for chip bonding. The upper adsorption device 1 can move with the movement of the horizontally and vertically movable support frame 13 . Similarly, the adsorption device 4 can move with the movement of the support frame 6 that can move horizontally and vertically. A microscope device (including an infrared light-emitting diode 10, a mirror 11, a beam splitter 8, an objective lens 7, an industrial camera 9 and a display 12) is placed under the support frame 13 and the support frame 6. The light emitted by the infrared light emitting diode 10 first passes through the reflector 11 , then passes through the beam splitter 8 , then passes through the objective lens 7 , and finally irradiates the chip through the through hole 14 . The reflected image passes through the objective lens 7, the beam splitter 8 is reflected to the industrial camera 9, and is transmitted to the display 12 through the data line. In order to adjust the field of view conveniently, a translation stage 16 and a translation stage 15 that can move horizontally and vertically are installed under the mirror 11 and the industrial camera 9, respectively.

The reflection angle of the mirror 11 can be adjusted arbitrarily. In the above example, 45° reflection is adopted, and other reflection structures can be adopted according to actual needs.

The lower adsorption device 4 is made of low-cost copper material, and a through hole 14 is drilled in the middle to pass light. Other thermally conductive materials can also be used for processing.

This example also provides a flip-chip bonding method. Please refer to the figure, the flip-chip bonding method includes the following steps, please refer to Figure 1 and Figure 2 at the same time for understanding:

Step 1: Fix the upper chip 2 and the lower chip 3 to be bonded with the upper adsorption device 1 and the lower adsorption device 4 respectively.

Step 2: Adjust the support frame 6 and the support frame 13 so that the two chips are infinitely close and the marking patterns on the two chips can be clearly seen on the display 12 .

Step 3: Change the position of the upper chip 2 according to the marking pattern until the marking pattern of the upper chip 2 and the marking pattern of the lower chip 3 are aligned.

Step 4: Turn on the heating function of the temperature control device 5, adjust the support frame 13 so that the upper chip 2 is pressed on the lower chip 3, and the bonding is completed.

The invention adopts the special optical path design of the infrared light source, and the infrared light has the ability to penetrate the chip, so there is no need to flip the chip or insert the observation device, and only need to observe directly, which greatly reduces the system error, and because there is no need to reverse or significantly Moving the chip, therefore, the displacement error is infinitely close to 0, and the error is around 15nm (depending on the displacement error of the automatic displacement platform used). The estimated bonding accuracy is around 200nm. Therefore, the error is greatly reduced and the bonding accuracy is improved.

Claims (10)

1. A reflective flip-chip bonding machine, characterized in that, comprising: The upper adsorption device used to install the upper chip; A lower adsorption device for installing the lower chip; a through hole arranged on the lower adsorption device; Infrared light-emitting diodes for emitting infrared light; a beam splitter arranged along the direction of the infrared light path of the infrared light emitting diode; an objective lens connected to the outgoing light of the beam splitter and facing the through hole; an industrial camera docked with the reflected light from the beam splitter; A display connected to the industrial camera. 2 . The reflective flip-chip bonding machine according to claim 1 , wherein the upper suction device and the lower suction device are disposed opposite to each other and cooperate with each other. 3 . 3 . The reflective flip-chip bonding machine according to claim 1 , wherein the upper suction device is connected with a support frame of the upper suction device. 4 . 4 . The reflective flip-chip bonding machine according to claim 1 , wherein the lower adsorption device is connected with a lower adsorption device support frame. 5 . 5 . The reflective flip-chip bonding machine according to claim 1 , wherein the lower adsorption device is connected with a temperature control device. 6 . 6 . The reflective flip-chip bonding machine according to claim 1 , wherein a reflection mirror is arranged between the infrared light-emitting diode and the beam splitter. 7 . 7 . The reflective flip-chip bonding machine according to claim 1 , wherein the mirror adopts a 45° reflection structure. 8 . 8 . The reflective flip-chip bonding machine according to claim 1 , wherein the mirror is arranged on the mirror displacement stage. 9 . 9 . The reflective flip-chip bonding machine according to claim 1 , wherein the industrial camera is arranged on an industrial camera displacement stage. 10 . 10. A flip-chip bonding method, characterized in that using the reflective flip-chip bonding machine according to any one of claims 1 to 9, comprising the following steps: Step 1: respectively fix the upper chip and the lower chip to be bonded with the upper adsorption device and the lower adsorption device; Step 2: Adjust the upper adsorption device support frame and the lower adsorption device support frame so that the two chips are close to each other and the marking patterns on the two chips can be clearly seen on the display; Step 3: Change the position of the upper chip according to the marking pattern, until the marking pattern of the upper chip and the marking pattern of the lower chip are aligned; Step 4: Turn on the heating function of the temperature control device, adjust the support frame of the lower adsorption device so that the upper chip is pressed on the lower chip, and the bonding is completed.

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