Method for preventing chip fracture in invisible cutting engineering

Abstract

The invention provides a method for preventing chip breakage in invisible cutting engineering. The method comprises the steps that a dynamic feedback laser focal length compensation system is adopted; a gradient material stress buffer layer is introduced into the SD layer structure; a nanosecond laser device and a picosecond laser device are integrated by using the self-adaptive multi-frequency laser collaborative processing device to carry out collaborative processing; adopting a dielectrophoresis-assisted particle adsorption process to adsorb nanoparticles to the surface of the chip; a multi-axis synchronous spectrum detection module is integrated to realize intelligent optimization of data; a modularized laser head rapid switching device is configured, and rapid switching of parameters of different process sections is achieved; and forming a plasma enhanced atomic layer deposition passivation layer on the surface of the chip. According to the method, through real-time temperature monitoring and laser focus dynamic adjustment, thermal damage in laser processing is avoided, the processing precision and the yield are improved, the gradient elastic modulus design of a nano multilayer film is adopted, interlayer stress is effectively dispersed, nanosecond laser and picosecond laser are used for cooperative processing, and through energy ratio adjustment, the residual height deviation is reduced.

Description

Technical Field

[0001] This invention relates to the field of advanced semiconductor packaging, and more particularly to the field of flip chip technology, specifically a method for preventing chip breakage through stealth dicing. Background Technology

[0002] As Flip chip bond products become larger and thinner, the chips are more prone to breakage during operation, leading to an increase in defective products.

[0003] During the early stages of development of the new product LC 32G DDR5, chip breakage occurred frequently. Through observation, the chip problems were found to be irregular. After analysis, it was found that the chip failure was caused by the breakage of the middle part. It is likely that the chip was not strong enough during operation and was prone to breakage.

[0004] As mass production plans progress, defects continue to occur during mass production verification, failing to meet current stable production requirements, necessitating urgent improvement of this issue. Summary of the Invention

[0005] In view of the shortcomings of the prior art described above, the purpose of this invention is to provide a method for preventing chip breakage during invisible cutting processes, thereby solving the difficulties of the prior art.

[0006] To achieve the above and other related objectives, the present invention provides a method for preventing chip breakage during stealth cutting engineering, comprising:

[0007] Step S1: A dynamic feedback laser focal length compensation system is used to collect real-time data on the temperature distribution of the chip surface and adjust the laser focus position accordingly.

[0008] Step S2: Introduce a gradient material stress buffer layer into the SD layer structure, using a TiAlN / TiSiN nanomultilayer film structure;

[0009] Step S3: Utilize an adaptive multi-frequency laser collaborative processing device to integrate nanosecond lasers and picosecond lasers for collaborative processing;

[0010] Step S4: Adsorb nano-Al2O3 particles onto the chip surface using a dielectrophoresis-assisted microparticle adsorption process;

[0011] Step S5: Integrate a multi-axis synchronous spectral detection module to achieve intelligent optimization of process parameter-stress data pairs;

[0012] Step S6: Configure a modular laser head rapid switching device to achieve rapid switching of parameters for different process sections;

[0013] Step S17: Form a plasma-enhanced atomic layer deposition passivation layer on the chip surface, which is composed of SiO2 / Al2O3 stacked thin films.

[0014] According to the preferred embodiment, the dynamic feedback laser focal length compensation system includes an infrared thermal imaging sensor array and a high-speed PID controller.

[0015] According to the preferred embodiment, the elastic modulus of the gradient material stress buffer layer decreases gradually from the matrix to the surface.

[0016] According to the preferred scheme, the adaptive multi-frequency laser collaborative processing device improves the control accuracy of residual height by adjusting the energy ratio.

[0017] According to a preferred embodiment, the dielectrophoresis-assisted microparticle adsorption mechanism includes a storage chamber for a suspension of nano-Al2O3 particles and an alternating electric field generator.

[0018] According to the preferred embodiment, the multi-axis synchronous spectral detection module consists of a Raman spectrometer and an XRD detector.

[0019] According to the preferred embodiment, the modular laser head rapid switching device includes a rotatable multi-station optical head compartment.

[0020] According to the preferred scheme, plasma-enhanced atomic layer deposition of passivation layer significantly improves chip edge strength and reduces defect density.

[0021] This invention avoids thermal damage during laser processing by real-time temperature monitoring and dynamic adjustment of the laser focus, thereby improving processing accuracy and yield. It adopts a gradient elastic modulus design of nano-multilayer films to effectively disperse interlayer stress. Nanosecond laser and picosecond laser are used in synergistic processing, and the residual height deviation is reduced by adjusting the energy ratio. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of the present invention clearer, the technical solutions of the embodiments of the present invention are described clearly and completely. It should be noted that the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the described embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0023] Unless otherwise defined, the technical or scientific terms used herein shall have the ordinary meaning understood by one of ordinary skill in the art to which this invention pertains. The terms “first,” “second,” and similar terms used in this patent application specification and claims do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Similarly, “an” or “a” and similar terms do not necessarily indicate a quantity limitation. Terms such as “comprising” or “including” mean that the element or object preceding the word encompasses the element or object listed following the word and its equivalents, without excluding other elements or objects. Terms such as “connected” or “linked” are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. Terms such as “upper,” “lower,” “left,” and “right” are used only to indicate relative positional relationships; these relative positional relationships may change accordingly when the absolute position of the described object changes.

[0024] This invention proposes a method for preventing chip breakage during invisible dicing processes in flip chip manufacturing. This invention does not limit the type of memory module, but this method for preventing chip breakage during invisible dicing processes is particularly suitable for 32G DDR5.

[0025] To reduce the frequency of chip breakage and address the issue in the background technology where frequent chip breakage occurred during the early stages of development of the new product LC 32G DDR5, observation revealed irregular chip problems. Analysis showed that the chip failure was caused by fractures in the middle section, indicating that the chip's strength was insufficient during operation, making it prone to breakage. Therefore, the technical solution provided in this embodiment utilizes a dynamic feedback laser focal length compensation system in conjunction with a gradient material stress buffer layer, combined with adaptive multi-frequency laser collaborative processing, to effectively improve the product manufacturing process, reduce the breakage rate, save costs, and increase production efficiency.

[0026] Specifically, the dynamic feedback laser focal length compensation system uses an infrared thermal imaging sensor array and a high-speed PID controller to collect real-time temperature distribution data on the chip surface and adjust the laser focal point position accordingly. The temperature data is transmitted to the PID controller via a PCIe interface. The controller uses a fuzzy PID algorithm to generate compensation commands. At the same time, the laser head is equipped with a six-dimensional adjustment stage, which can achieve micron-level dynamic compensation along the Z-axis.

[0027] As mentioned earlier, a gradient material stress buffer layer is introduced into the SD layer structure, employing a TiAlN / TiSiN nanolayered film structure. The elastic modulus of this layer decreases gradually from the substrate to the surface, achieving directional stress wave dissipation, crack propagation suppression, and optimized thermo-mechanical compatibility. Its application in chip stealth dicing significantly improves dicing yield and substantially enhances chip reliability during packaging and use.

[0028] Based on this, the adaptive multi-frequency laser collaborative processing device integrates nanosecond lasers and picosecond lasers for collaborative processing. The nanosecond laser is responsible for 90% of material removal, while the picosecond laser performs fine finishing. The two beams are combined through a dichroic mirror, and the focal distance needs to be precisely controlled at the micrometer level. The adaptive multi-frequency laser collaborative processing device improves the control accuracy of residual height by adjusting the energy ratio, so that the roughness of the cut is ≤50nm.

[0029] For microcracks, nano-Al2O3 particles are used for filling. The dielectrophoresis-assisted microparticle adsorption mechanism includes a nano-Al2O3 particle suspension storage chamber and an alternating electric field generator, which avoids the agglomeration problem of traditional spraying methods, effectively improving the bending strength liquid. Moreover, the Al2O3 particles form a dense protective layer, and its high hardness and thermal stability can improve the chip's crack resistance and reduce the risk of microcrack propagation caused by cutting stress.

[0030] Next, Raman spectroscopy is used to monitor the vibrational state of material molecules in real time and identify lattice distortion caused by thermal stress; XRD is used to detect changes in crystal structure at the same time. The two complement each other to form a complete application database. XRD is sensitive to microcracks, while Raman can locate the chemical composition of defects and provide early warning of potential rupture winds.

[0031] It should be noted that the modular laser head rapid switching device achieves rapid switching of laser heads in chip stealth cutting through a rotatable multi-station optical head compartment design. At the same time, the use of a high-rigidity harmonic reducer to drive the rotation can also avoid optical path deviation caused by traditional mechanical switching.

[0032] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A method for preventing chip breakage during stealth cutting engineering, characterized in that, include: Step S1: A dynamic feedback laser focal length compensation system is used to collect real-time data on the temperature distribution of the chip surface and adjust the laser focus position accordingly. Step S2: Introduce a gradient material stress buffer layer into the SD layer structure, using a TiAlN / TiSiN nanomultilayer film structure; Step S3: Utilize an adaptive multi-frequency laser collaborative processing device to integrate nanosecond lasers and picosecond lasers for collaborative processing; Step S4: Adsorb nano-Al2O3 particles onto the chip surface using a dielectrophoresis-assisted microparticle adsorption process; Step S5: Integrate a multi-axis synchronous spectral detection module to achieve intelligent optimization of process parameter-stress data pairs; Step S6: Configure a modular laser head rapid switching device to achieve rapid switching of parameters for different process sections; Step S17: Form a plasma-enhanced atomic layer deposition passivation layer on the chip surface, which is composed of SiO2 / Al2O3 stacked thin films.

2. The method for preventing chip breakage during stealth cutting engineering according to claim 1, characterized in that, The dynamic feedback laser focal length compensation system includes an infrared thermal imaging sensor array and a high-speed PID controller.

3. The method for preventing chip breakage during stealth cutting engineering according to claim 2, characterized in that, The elastic modulus of the gradient material stress buffer layer decreases gradually from the matrix to the surface.

4. The method for preventing chip breakage during stealth cutting engineering according to claim 3, characterized in that, The adaptive multi-frequency laser collaborative processing device improves the accuracy of residual height control by adjusting the energy ratio.

5. The method for preventing chip breakage during stealth cutting engineering according to claim 4, characterized in that, The dielectric-assisted microparticle adsorption mechanism includes a storage chamber for a suspension of nano-Al2O3 particles and an alternating electric field generator.

6. The method for preventing chip breakage during stealth cutting engineering according to claim 5, characterized in that, The multi-axis synchronous spectral detection module consists of a Raman spectrometer and an XRD detector.

7. The method for preventing chip breakage in stealth cutting engineering according to claim 6, characterized in that, The modular laser head rapid switching device includes a rotatable multi-station optical head compartment.