Redistribution structure manufacturing process in integrated circuit packaging

Abstract

This invention relates to the field of semiconductor packaging technology and discloses a manufacturing process for a redistribution structure in integrated circuit packaging, comprising: coating a dielectric polymer precursor on a substrate surface and heat-treating it to a semi-cured state, so that the initial crosslinking degree is in the range of 25% to 40%; sputtering a first metal seed layer with a power of 300W to 500W, using particle bombardment energy to induce a high crosslinking density surface layer in situ on the polymer surface, while constructing a complex bonding interface between the metal and polymer functional groups; subsequently increasing the power to 1500W to 2500W to deposit a second metal seed layer, using the high crosslinking density surface layer to block atomic penetration; and finally thermal curing. This invention effectively solves the polymer thermal damage caused by high-power deposition by constructing an in-situ shell formation mechanism in a semi-cured transient state, synergistically achieving adaptive relaxation of interface stress and hybrid enhancement of interlayer bonding force.

Description

Technical Field

[0001] This invention relates to a manufacturing process for a redistribution structure in integrated circuit packaging, belonging to the field of semiconductor packaging technology. Background Technology

[0002] In current integrated circuit packaging technology, redistribution structures are key components for achieving high-density signal interconnection. Their manufacturing process typically involves stacking dielectric polymers such as polyimide with metal layers formed by physical vapor deposition and electrochemical plating. In the mainstream approach in this field, after the dielectric polymer layer reaches a fully cured state, a metal seed layer is deposited on its surface to ensure that the dielectric layer has sufficient mechanical modulus to withstand the metal deposition pressure. However, as the number of redistribution layers increases and the line density improves, the mismatch in thermal expansion coefficients between the dielectric layer and the metal layer becomes increasingly apparent. Existing processes require the polymer to reach a fully cross-linked state before metallization. At this point, the polymer chain segments have lost their microscopic slip capability, and the interface locks the intrinsic stress generated during subsequent metal layer deposition and annealing. The continuous accumulation of such stress causes irreversible warping deformation of the wafer, which not only interferes with the photolithography focusing accuracy but also threatens the structural stability of subsequent processes such as wafer thinning.

[0003] To address interface damage and structural stability, existing technologies primarily improve upon the physical structure of material stacking. However, besides limitations in hardware form, there are also shortcomings in control methods. For example, Chinese invention patent application CN112786465A discloses a semiconductor structure and its fabrication method, which adds a hard dielectric layer between the redistribution layer and the polymer layer. The mechanical hardness of the dielectric layer provides stress feedback for the bonding wires and acts as an etching barrier layer to protect the polymer. This approach has fundamental limitations in addressing overall stress mismatch induced by high-density wiring. Essentially, it introduces a physical separation interface into the multilayer heterogeneous structure, increasing process complexity. The bottom polymer is in a rigid, high-crosslink density state, unable to provide a stress dissipation path. The abrupt change in modulus between the hard dielectric layer and the polymer leads to interface delamination risk. To address the aforementioned interface stress accumulation problem, attempts are typically made to lower the annealing temperature or introduce a low-modulus buffer layer. Analysis shows that lowering the annealing temperature leads to insufficient polymer crosslinking, thus reducing the electrical insulation performance of the dielectric layer. Introducing a heterogeneous buffer material not only increases process complexity but also introduces a new physical separation interface within the structure, reducing the overall reliability of the redistribution structure.

[0004] Therefore, how to utilize the physical properties of the medium polymer during the crosslinking evolution process to achieve in-situ stress dissipation and stress release while ensuring interfacial adhesion strength has become the technical problem to be solved by this invention. Summary of the Invention

[0005] To address the problems mentioned in the background art, the technical solution of the present invention is as follows: A manufacturing process for a redistribution structure in integrated circuit packaging, comprising the following steps: Step S1: A dielectric polymer precursor is coated on the substrate surface, and a first heat treatment process is performed to form a pre-cured dielectric polymer layer, wherein the initial crosslinking degree of the pre-cured dielectric polymer layer is 25% to 40%. Step S2: Perform the first-stage sputtering process, turn on the metal target and set the sputtering power to 300W to 500W. Use the heat generated by the sputtering particles bombarding the surface of the pre-cured dielectric polymer layer to induce a secondary cross-linking reaction on the surface layer of the pre-cured dielectric polymer layer, forming a high cross-linking density surface layer with a thickness of 3nm to 8nm and a cross-linking degree higher than the initial cross-linking degree. Then, deposit a first metal seed crystal layer with a thickness of 5nm to 15nm on the surface of the high cross-linking density surface layer. The active functional groups remaining in the pre-cured dielectric polymer layer coordinate with the metal atoms of the first metal seed crystal layer to form a complex bonding interface. Step S3: Perform the second-stage sputtering process, increase the sputtering power to 1500W to 2500W, deposit a second metal seed layer on the surface of the first metal seed layer, and use the high cross-linking density surface layer to block metal atoms from penetrating into the pre-cured dielectric polymer layer. Step S4: Perform a second heat treatment process to transform the pre-cured dielectric polymer layer into a fully cured dielectric polymer layer.

[0006] Preferably, the complex bonding interface has a metal-polymer complex bond network composed of active functional groups and metal atoms; the interfacial bonding force generated by the metal-polymer complex bond network during step S4 is not less than the interfacial normal stress generated by the volume shrinkage of the fully cured dielectric polymer layer, so as to maintain the interfacial integrity between the first metal seed crystal layer and the fully cured dielectric polymer layer.

[0007] Preferably, before performing step S2, the method further includes: step S5, monitoring the pressure in the sputtering chamber using a vacuum gauge, and when the pressure reaches 5... 10 Pa to 8 10 At Pa, argon gas is introduced into the sputtering chamber and the ignition operation is performed.

[0008] Preferably, during step S4, by adjusting the temperature of the heating stage on the back side of the substrate, the pre-cured dielectric polymer layer forms a curing gradient in the thickness direction that increases from the substrate to the first metal seed layer, so that the crosslinking rate of the pre-cured dielectric polymer layer near the substrate is slower than the crosslinking rate of the high crosslinking density surface layer.

[0009] Preferably, the degree of crosslinking of the high crosslinking density surface layer formed in step S2 satisfies the following relationship: ,in, For a high cross-linking density surface layer, denoted as the initial degree of crosslinking of the pre-cured dielectric polymer layer, and k is the thermally induced crosslinking enhancement factor, which is limited to 1.5 to 2.2.

[0010] Preferably, the dielectric polymer precursor is photosensitive polyimide or photosensitive polybenzobisazole; the temperature of the first heat treatment process is 100°C to 120°C, and the treatment time is 180s to 300s.

[0011] Preferably, after performing step S3, the method further includes: step S6, coating photoresist on the surface of the second metal seed layer, and forming a circuit pattern window through exposure and development processes; step S7, performing an electroplating process to fill the circuit pattern window with a metal conductor layer; and step S8, removing the photoresist and etching away the first metal seed layer and the second metal seed layer that are not covered by the metal conductor layer.

[0012] Preferably, the metal conductor layer is made of copper; during step S8, ammonium persulfate solution is used as the etching solution, and the temperature of the etching solution is controlled to be 30°C to 40°C.

[0013] Preferably, the duration of the first-stage sputtering process is 20s to 40s; the duration of the second-stage sputtering process is 120s to 180s, and the thickness of the second metal seed layer is 100nm to 150nm.

[0014] Preferably, during step S1, the coating thickness of the pre-cured dielectric polymer layer is 5 μm to 10 μm; before step S2, the surface of the pre-cured dielectric polymer layer is activated using oxygen plasma to improve the chemical wettability of the surface.

[0015] Compared with the prior art, the beneficial effects of the present invention are: 1. In integrated circuit packaging, mechanical locking of interface stress is eliminated and in-situ stress dissipation is achieved. By controlling the first heat treatment to maintain the dielectric layer at 60% to 75% curing degree, the viscoelastic characteristics and micro-creep capabilities of the polymer in this transient state are utilized to absorb the initial displacement gradient generated during the formation of metal wires. The second heat treatment drives the dielectric layer to transform from a semi-cured state to a fully cured state, so that the final cross-linking process of molecules and the stress release process occur simultaneously. The intrinsic stress originally locked at the interface is transformed into the release of internal energy during the rearrangement of molecular chain segments, eliminating the shear stress accumulation between the layers of the multilayer redistribution structure and ensuring the overall coplanarity of large-size wafers under high-density wiring.

[0016] 2. Construct an interface barrier mechanism with asymmetric modulus distribution. During the formation of the metal seed layer, the sputtering latent heat generated by the bombardment of metal atoms induces a transient temperature field on the surface of the dielectric layer, driving the local high-speed condensation of the semi-cured dielectric layer at its outermost surface, generating a highly dense and rigid barrier layer in situ. Due to the low thermal conductivity of the polymer material, the hysteresis effect of heat transfer allows the bulk region to maintain a low degree of curing to preserve stress compensation space. Thus, without introducing a heterogeneous intermediate layer, the heterogeneous evolution of the material's own state not only blocks the risk of leakage caused by the penetration of high-energy metal ions into the dielectric layer, but also maintains the overall structure's ability to neutralize interface stress.

[0017] 3. The interface bonding mode is transformed from physical adsorption to chemical bonding. By utilizing the active monomers remaining in the semi-cured dielectric layer, they can directly coordinate with sputtered high-energy metal atoms during the metal deposition stage to construct chemical anchoring points. This in-situ anchoring mechanism based on residual functional groups transforms the bonding mode between the seed layer and the dielectric layer into a hybrid mode of chemical bonding and physical adsorption. This can resist the volume shrinkage stress generated by the polymer in the final curing stage, suppress the micro-peeling phenomenon caused by uneven interface slip, and improve the interface integrity and signal transmission stability of the redistribution structure under extreme thermal cycling conditions. Attached Figure Description

[0018] Figure 1 This is a flowchart of the stepped sputtering and curing process for the redistribution structure manufacturing process of the present invention. Figure 2 This is a diagram illustrating the implementation architecture of real-time monitoring of process parameters and interface modification in this invention.

[0019] The objectives, features, and advantages of this invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0020] The technical solutions of the embodiments of this application will be clearly described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of this application are within the scope of protection of this application.

[0021] A manufacturing process for a redistribution structure in an integrated circuit package includes the following steps: Step S1: A dielectric polymer precursor is coated on the substrate surface, and a first heat treatment process is performed to form a pre-cured dielectric polymer layer, wherein the initial crosslinking degree of the pre-cured dielectric polymer layer is 25% to 40%. Step S2: Perform the first-stage sputtering process, turn on the metal target and set the sputtering power to 300W to 500W. Use the heat generated by the sputtering particles bombarding the surface of the pre-cured dielectric polymer layer to induce a secondary cross-linking reaction on the surface layer of the pre-cured dielectric polymer layer, forming a high cross-linking density surface layer with a thickness of 3nm to 8nm and a cross-linking degree higher than the initial cross-linking degree. Then, deposit a first metal seed crystal layer with a thickness of 5nm to 15nm on the surface of the high cross-linking density surface layer. The active functional groups remaining in the pre-cured dielectric polymer layer coordinate with the metal atoms of the first metal seed crystal layer to form a complex bonding interface. Step S3: Perform the second-stage sputtering process, increase the sputtering power to 1500W to 2500W, deposit a second metal seed layer on the surface of the first metal seed layer, and use the high cross-linking density surface layer to block metal atoms from penetrating into the pre-cured dielectric polymer layer. Step S4: Perform a second heat treatment process to transform the pre-cured dielectric polymer layer into a fully cured dielectric polymer layer.

[0022] Preferably, the complex bonding interface has a metal-polymer complex bond network composed of active functional groups and metal atoms; the interfacial bonding force generated by the metal-polymer complex bond network during step S4 is not less than the interfacial normal stress generated by the volume shrinkage of the fully cured dielectric polymer layer, so as to maintain the interfacial integrity between the first metal seed crystal layer and the fully cured dielectric polymer layer.

[0023] Preferably, before performing step S2, the method further includes: step S5, monitoring the pressure in the sputtering chamber using a vacuum gauge, and when the pressure reaches 5... 10 Pa to 8 10 At Pa, argon gas is introduced into the sputtering chamber and the ignition operation is performed.

[0024] Preferably, during step S4, by adjusting the temperature of the heating stage on the back side of the substrate, the pre-cured dielectric polymer layer forms a curing gradient in the thickness direction that increases from the substrate to the first metal seed layer, so that the crosslinking rate of the pre-cured dielectric polymer layer near the substrate is slower than the crosslinking rate of the high crosslinking density surface layer.

[0025] Preferably, the degree of crosslinking of the high crosslinking density surface layer formed in step S2 satisfies the following relationship: ,in, For a high cross-linking density surface layer, denoted as the initial degree of crosslinking of the pre-cured dielectric polymer layer, and k is the thermally induced crosslinking enhancement factor, which is limited to 1.5 to 2.2.

[0026] Preferably, the dielectric polymer precursor is photosensitive polyimide or photosensitive polybenzobisazole; the temperature of the first heat treatment process is 100°C to 120°C, and the treatment time is 180s to 300s.

[0027] Preferably, after performing step S3, the method further includes: step S6, coating photoresist on the surface of the second metal seed layer, and forming a circuit pattern window through exposure and development processes; step S7, performing an electroplating process to fill the circuit pattern window with a metal conductor layer; and step S8, removing the photoresist and etching away the first metal seed layer and the second metal seed layer that are not covered by the metal conductor layer.

[0028] Preferably, the metal conductor layer is made of copper; during step S8, ammonium persulfate solution is used as the etching solution, and the temperature of the etching solution is controlled to be 30°C to 40°C.

[0029] Preferably, the duration of the first-stage sputtering process is 20s to 40s; the duration of the second-stage sputtering process is 120s to 180s, and the thickness of the second metal seed layer is 100nm to 150nm.

[0030] Preferably, during step S1, the coating thickness of the pre-cured dielectric polymer layer is 5 μm to 10 μm; before step S2, the surface of the pre-cured dielectric polymer layer is activated using oxygen plasma to improve the chemical wettability of the surface.

[0031] Example 1: In the manufacturing process of redistribution structures for integrated circuit packaging, for a wiring structure with submicron linewidth and six dielectric stacks, when the 300mm wafer is in the metallization stage, a modulus difference exists between the dielectric polymer layer and the metal layer, causing mechanical locking of the interface stress in the fully cured state, resulting in wafer coplanarity deviation. Using this manufacturing process, a photosensitive polyimide precursor is coated on the substrate surface, and a first heat treatment process is used to reduce the initial crosslinking degree of the dielectric layer. By controlling the crosslinking density between 25% and 40%, the pre-cured dielectric polymer layer is kept in a semi-cured state with structural support and creep characteristics. Before performing the first-stage sputtering process, the vertical distance between the metal target and the substrate is fixed at 150 mm, and a substrate back-cooling circulation system with a flow rate of 12 L / min and a constant water temperature of 20 °C is turned on. By setting the first sputtering power to 300 W to 500 W, the energy flux of the sputtered particle stream to the polymer surface is controlled, so that the instantaneous surface temperature rise gradient caused by it within 10 s is maintained in the range of 3 °C to 5 °C per second. Thus, without destroying the 25% crosslinked bulk structure of the bottom layer, the molecular chain segments of the polar surface layer are driven to undergo secondary polycondensation with a depth of 3 nm to 8 nm. Because the surface layer with high crosslinking density has undergone thermal kinetic energy enhancement in advance, its complex modulus soars from 100 MPa to more than 1.2 GPa in the early stage of sputtering, which has the mechanical strength and thermal shielding threshold to withstand the impact of 1500 W high-power particles.

[0032] The wafer is placed in the vacuum chamber of a physical vapor deposition (PVD) system. A first-stage sputtering process is employed, with the initial sputtering power of the metal target set to 300W to 500W. A first metal seed layer with a thickness of 5nm to 15nm is deposited on the surface of a pre-cured dielectric polymer layer in a semi-cured state. The transient latent heat generated by the sputtering particle bombardment induces a secondary cross-linking reaction on the outermost layer of the dielectric layer, forming a cross-linked layer with a thickness of 3nm to 8nm. A high cross-linking density surface layer, higher than that of the bulk region, acts as an interface barrier layer. During the second-stage sputtering process with a power of 1500W to 2500W, it blocks the penetration of metal atoms into the semi-cured bulk, preventing insulation failure caused by metal particle migration. A second heat treatment process is used to transform the semi-cured bulk dielectric layer from a transient state to a fully cured state, dissipating the initial displacement gradient and intrinsic stress at the interface during molecular chain rearrangement. This process eliminates the shear stress accumulation of the multilayer redistribution structure without introducing a heterogeneous buffer layer, maintaining the interface integrity and overall flatness of the multilayer high-density wiring structure under thermal cycling conditions.

[0033] Example 2: In the experiment verifying the reliability of the redistribution structure manufacturing process in integrated circuit packaging, a physical vapor deposition platform including in-situ stress monitoring components and high-precision current characterization instruments was used to determine the correlation between interface stress and electrical insulation performance. This platform was installed in a 300mm vacuum chamber, and a laser displacement sensor with a resolution of 0.1μm was used to monitor wafer surface deformation. The sampling frequency was set to 100Hz. Simultaneously, a mechanical disturbance with an amplitude of 0.5μm was applied to the substrate base to simulate actual production line conditions. Regarding the initial crosslinking degree... The parameter settings involve a technical trade-off between simultaneously satisfying the creep capability of the dielectric layer and the stability of the pattern structure. The initial degree of crosslinking of the dielectric polymer layer is given. When the complex modulus of the dielectric layer is in the range of 10 MPa to 100 MPa, the molecular chain segments retain displacement slip space. The initial degree of crosslinking is determined by calculating the viscoelastic response curve of the polymer near the gel point. The working window is 25% to 40%; in this comparative experiment, the experimental group selected the initial degree of crosslinking. The experimental group consisted of 32% crosslinked samples, while the control group consisted of fully cured samples with an initial crosslinking degree of 95%. The first stage of sputtering was performed, with the metal target activated and the initial sputtering power set to 400W. It was observed that under sputtering particle bombardment, the surface layer of the experimental group underwent a secondary crosslinking reaction, forming a layer with a thickness of 4.8 nm and a high degree of crosslinking. The surface layer has a higher cross-linking density than the bulk region, in which... The degree of crosslinking of the dielectric polymer layer surface layer; after depositing a 10.2 nm thick first metal seed layer, the surface hardness of the experimental group increased from 0.22 GPa to 1.48 GPa, while the surface hardness of the control group remained at 1.83 GPa and no gradient crosslinking structure was generated; the second stage sputtering process was performed, the sputtering power was increased to 2000 W, and a second metal seed layer with a thickness of 100.5 nm was deposited.

[0034] The experimental group exhibited nonlinear stress response characteristics, reaching a performance inflection point at 10 s of deposition duration, with the wafer center warpage increasing from 5.2 μm to 11.4 μm. In contrast, the control group's warpage jumped from 8.1 μm to 152.6 μm within the same timeframe. Boundary verification of the first metal seed layer thickness showed that when the 3.5 nm thick oversized sample was subjected to high-energy sputtering, the metal atoms penetrated to a depth of 21.4 nm into the bulk, and the leakage current density increased to 5.8e-8 A / cm², while the thickness of 10.2 nm... The leakage current density of the experimental group at nm remained stable at 1.45e-12 A / cm², confirming the blocking effect of the high cross-linking density surface layer on high-energy particles. After completing the second heat treatment process, the metal-polymer complex network formed at the interface of the experimental group resulted in a peel strength of 0.84 kg / cm, which was higher than the 0.41 kg / cm of the control group. In step S4, the heating stage on the back side of the substrate in the second heat treatment process adopted a zoned temperature control mode, setting an increasing temperature compensation value from the center to the edge to offset the heat loss at the wafer edge and maintain the temperature difference on the wafer surface at [value missing]. Within a range of ±1.5℃, the heating rate of the heating stage was limited to 3℃ / min to 5℃ / min. Under the controlled temperature field, the pre-cured dielectric polymer layer underwent micro-creep, and the complex modulus smoothly transitioned from 100MPa to over 2GPa in the fully cured state as the degree of crosslinking increased. The residual displacement gradient generated by the deposition of the metal seed crystal layer was absorbed by the molecular chain segment rearrangement. The final redistribution structure was characterized by nanoindentation, and the interface hardness showed a decreasing gradient distribution from the metal layer to the polymer bulk. This verified the modulus transition between the high crosslinking density surface layer and the bulk region, reducing the probability of interfacial shear failure of the multilayer stacked structure under thermal cycling. After 1000 thermal cycles in the temperature range of -55℃ to 125℃, the control group showed a 12.5μm wide crack propagation at the interface, while the experimental group structure remained intact and the final wafer warpage value stabilized at 34.2μm. This experimental conclusion confirms that by controlling the semi-cured transient effect generated by the initial degree of crosslinking, combined with the in-situ induced high crosslinking density surface layer, intrinsic stress can be dissipated while maintaining the electrical insulation reliability of the redistribution structure.

[0035] Example 3: In the manufacturing process of a multilayer redistribution structure, the solvent evaporation rate of the photosensitive polyimide precursor is affected by fluctuations in ambient humidity; when the time of the first heat treatment process is fixed, the degree of crosslinking of the dielectric polymer layer easily deviates from the preset range, leading to uncontrolled thickness of the interface barrier layer and metal atom penetration; after coating the photosensitive polyimide precursor on the substrate surface, the polymer at 1378 nm is extracted using an infrared spectroscopy monitoring unit. Intensity of the imide ring vibration peak at the location With 1500 The intensity of the benzene ring vibration peak at the location Determine the initial degree of crosslinking based on absorbance data. The calculation formula is as follows: ,in, The initial degree of crosslinking of the dielectric polymer layer, The peak intensity of the imide ring vibration. The intensity of the benzene ring vibration peak, K is a proportionality constant, and it is pre-calibrated by the absorbance ratio of the sample group in the fully cured state. Step S1, the initial crosslinking degree of the pre-cured dielectric polymer layer. The temperature-time-crosslinking degree mapping table was constructed online, and the construction procedure was as follows: Substrates coated with photosensitive polyimide precursors from the same batch were selected and sampled under gradient baking conditions from 100℃ to 120℃. Infrared spectroscopy was used to extract... Intensity of the imide ring vibration peak and Intensity of the benzene ring vibration peak Calculate the absorbance ratio The ratio of samples baked at 350℃ for 60 minutes was defined as the curing baseline value. Determine the initial degree of crosslinking The infrared monitoring unit during the production process collects absorbance data in real time and calculates... The value enters the target range of 25% to 40% and the rate of change If the percentage is less than 0.05% / min for 30 consecutive seconds, stop the first heat treatment.

[0036] when When the temperature reaches 30%, the first heat treatment process is stopped and the wafer is loaded into the sputtering chamber; the first stage sputtering process is executed, and the first sputtering power is set to 400W; the duration of the first stage is... The calculation formula is as follows: ,in, The duration of the first phase, To achieve a high cross-linking density surface layer thickness, At the predetermined deposition rate, at the end of this time period, the dense structure formed by the thermal energy-driven dielectric polymer layer at the surface possesses the ability to resist ion bombardment. At this point, the power is increased to 2000W to execute the second-stage sputtering process; the second heat treatment process is then executed, with a heating rate set at 3.5℃ / min. Under this temperature field, the free volume within the semi-cured bulk dielectric layer increases, and long chain segments undergo displacement rearrangement, neutralizing the interfacial shear displacement generated by the first-stage sputtering. As the density of chemical crosslinking points increases, the dielectric polymer layer transitions from a viscoelastic state to a glassy state, locking in the equilibrium conformation of the molecular chain segments. The above operating procedure eliminates the uncertainty of the dielectric polymer layer state. The cumulative warpage value of the redistribution structure under six-layer stacking conditions is 28.2μm, and the breakdown voltage intensity between dielectric layers is 355V / μm. This result confirms that by accurately calibrating the initial crosslinking state and matching the gradient power switching logic, it is possible to eliminate the overall deformation deviation of the redistribution structure by utilizing the transient characteristics of the material while ensuring the electrical insulation performance of the redistribution layer.

[0037] Example 4: When the system faces spectral absorption shift caused by batch replacement of photosensitive polyimide precursors, the value of the scaling factor K is determined before the coating process. Five reference sample groups with a thickness of 10 μm are prepared on the test wafer surface and placed in a vacuum oven. These samples are then maintained at temperatures of 150℃, 200℃, 250℃, 300℃, and 350℃ for 60 minutes, respectively. The infrared spectroscopy monitoring unit is used to extract the spectral density of each sample group at 1378 ppm. Intensity of the imide ring vibration peak at the location and 1500 The intensity of the benzene ring vibration peak at the location The absorbance ratio corresponding to the 350℃ sample group was used as the benchmark for complete cross-linking. The proportionality coefficient K was calculated using the least squares method, and this coefficient was used to solve for the initial degree of cross-linking. Regarding the calibration method of the proportional coefficient, five standard sample groups from the same batch were selected and forced to bake in a nitrogen environment at 350℃ for 60 minutes. The absorbance ratio of the imide ring vibration peak to the benzene ring vibration peak at this time was extracted using an infrared spectrometer. The measured value of this ratio was set as the denominator reference value of 1.000. In subsequent production sampling, the real-time extracted ratio was divided by this reference value and multiplied by 100. The resulting value is the crosslinking degree in percentage form. The determination of the thermally induced crosslinking enhancement coefficient was based on destructive cross-sectional testing of a sample group with a thickness of 5nm at a sputtering power of 400W.

[0038] By recording the average crosslinking degree of the high-crosslinking density surface layer and the crosslinking degree of the unbombarded bulk layer, a linear regression model was established for 10 sampling points. The slope of this model was used as a fixed enhancement factor. In manufacturing scenarios with specific tolerance requirements for deposition thickness deviation, to neutralize the impedance fluctuations caused by adsorbed charges on the sputtering chamber walls, vacuum environment initialization was performed before starting the first stage of the sputtering process. A vacuum gauge was used to monitor and stabilize the base pressure of the sputtering chamber. After introducing argon gas at a flow rate of 50 sccm and adjusting the throttle valve to maintain a constant working pressure of 0.5 Pa, with the shielded shutter closed, the first sputtering power was set to 400 W, and the deposition rate was monitored using a quartz crystal microbalance sensor. Deposition rate When the fluctuation amplitude is less than 0.01 nm / s for 10 consecutive seconds, the rate value is transmitted to the control unit to calculate the duration of the first stage. This keeps the thickness of the highly cross-linked surface layer in the range of 3nm to 8nm.

[0039] Example 5: When the system faces dynamic viscosity η fluctuations caused by batch changes of photosensitive polyimide precursors, a calibration procedure for the proportionality coefficient K is performed before the coating process. The dynamic viscosity η of the current batch of precursors is extracted using a rotational viscometer at 25°C, and the initial degree of crosslinking is calculated by combining the real-time absorbance data fed back by the infrared spectroscopy monitoring unit. until the initial degree of crosslinking. The crosslinking degree is in the range of 25% to 40% and the rate of change of crosslinking degree over time. If the viscosity is less than 0.05% / min within a continuous 30s monitoring window, the dielectric polymer layer is considered to have reached a semi-cured state with creep characteristics; where η is the initial dynamic viscosity of the precursor and K is the proportionality coefficient. The initial degree of crosslinking of the dielectric polymer layer, The rate of change of crosslinking degree over time, when the system faces the deposition rate within the physical vapor deposition chamber. During fluctuating operating conditions, the target material wear status is calibrated before starting the first stage of the sputtering process. The instantaneous deposition rate at 400W sputtering power is monitored using a quartz crystal microbalance sensor installed in the physical vapor deposition equipment chamber. The instantaneous deposition rate When the standard deviation of the fluctuation is less than 0.005 nm / s within a 10s sampling period, the thickness of the high cross-linking density surface layer is controlled by the built-in rate feedback loop of the physical vapor deposition equipment. The metal target is turned on and the sputtering power is stabilized in the range of 300W to 500W. The shielding shutter is kept closed, and the instantaneous deposition rate of metal atoms is monitored by a quartz crystal microbalance sensor. When the standard deviation of the fluctuation meets the preset requirements, the control unit determines the target thickness. according to Calculate the duration of the first stage sputtering. , With a value of 5.2nm, the shutter timing is activated. At the instant time t is reached, the power control module switches the output power to the 1500W to 2500W required in step S3. The dense surface layer formed in the first stage is used to construct a physical barrier, preventing high-energy particles from penetrating into the dielectric polymer layer. The current measured rate value is used as input to calculate the duration required to generate a 5.2nm thick, highly cross-linked surface layer. And at the moment of its end, the sputtering power is switched from 400W to 2000W to keep the interlayer thickness deviation of the multilayer redistribution structure within 0.15nm.

[0040] In manufacturing scenarios where atomic-level characterization of the interfacial adhesion stability of redistribution structures is required, to confirm the microscopic evolution of the metal-polymer complex network, a first-stage sputtering process is used to determine the initial crosslinking degree. A secondary cross-linking reaction was induced in the 32% dielectric polymer layer at the electrode surface. Simultaneously, the chemical activity of metal atoms generated by physical vapor deposition was utilized to induce orbital hybridization between copper atoms and amino residues at the ends of semi-cured polymer chain segments. Synchrotron radiation photoelectron spectroscopy analysis was used to monitor the interfacial layer. The binding energy shift of 0.8 eV generated by the energy spectrum peak confirms that copper atoms and nitrogen atoms construct a complex structure with covalent properties through coordination. As the temperature of the second heat treatment process increases, the bulk molecular chains in the creep state drive the complex nodes to undergo spatial rearrangement, forming a hybrid interpenetrating network with a gradient distribution of crosslinking density in the interface region. This hybrid interpenetrating network increases the binding energy between the metal layer and the polymer layer to above 1.5 eV, blocking the penetration of microcracks caused by stress concentration during thermal cycling into the bulk at the atomic level, thus achieving the mechanical stability of the six-layer high-density redistribution structure under temperature cycling from -65℃ to 150℃.

[0041] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the present invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the present invention.

[0042] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention.

Claims

1. A manufacturing process for a redistribution structure in integrated circuit packaging, characterized in that, Includes the following steps: Step S1: A dielectric polymer precursor is coated on the substrate surface, and a first heat treatment process is performed to form a pre-cured dielectric polymer layer, wherein the initial crosslinking degree of the pre-cured dielectric polymer layer is 25% to 40%. Step S2: Perform the first-stage sputtering process, turn on the metal target and set the sputtering power to 300W to 500W. Use the heat generated by the sputtering particles bombarding the surface of the pre-cured dielectric polymer layer to induce a secondary cross-linking reaction on the surface layer of the pre-cured dielectric polymer layer, forming a high cross-linking density surface layer with a thickness of 3nm to 8nm and a cross-linking degree higher than the initial cross-linking degree. Then, deposit a first metal seed crystal layer with a thickness of 5nm to 15nm on the surface of the high cross-linking density surface layer. The active functional groups remaining in the pre-cured dielectric polymer layer coordinate with the metal atoms of the first metal seed crystal layer to form a complex bonding interface. Step S3: Perform the second-stage sputtering process, increase the sputtering power to 1500W to 2500W, deposit a second metal seed layer on the surface of the first metal seed layer, and use the high cross-linking density surface layer to block metal atoms from penetrating into the pre-cured dielectric polymer layer. Step S4: Perform a second heat treatment process to transform the pre-cured dielectric polymer layer into a fully cured dielectric polymer layer.

2. The manufacturing process for a redistribution structure in an integrated circuit package according to claim 1, characterized in that, The complex bonding interface has a metal-polymer complex bond network composed of active functional groups and metal atoms; the interfacial bonding force generated by the metal-polymer complex bond network during step S4 is not less than the interfacial normal stress generated by the volume shrinkage of the fully cured dielectric polymer layer, so as to maintain the interfacial integrity between the first metal seed crystal layer and the fully cured dielectric polymer layer.

3. The manufacturing process for a redistribution structure in an integrated circuit package according to claim 1, characterized in that, Before performing step S2, the procedure also includes: step S5, which involves monitoring the pressure in the sputtering chamber using a vacuum gauge, and when the pressure reaches 5... 10 Pa to 8 10 At Pa, argon gas is introduced into the sputtering chamber and the ignition operation is performed.

4. The manufacturing process for a redistribution structure in an integrated circuit package according to claim 1, characterized in that, During step S4, by adjusting the temperature of the heating stage on the back side of the substrate, a curing degree gradient is formed in the thickness direction of the pre-cured dielectric polymer layer, increasing from the substrate to the first metal seed layer, so that the crosslinking rate of the pre-cured dielectric polymer layer near the substrate is slower than the crosslinking rate of the high crosslinking density surface layer.

5. The manufacturing process for a redistribution structure in an integrated circuit package according to claim 1, characterized in that, The degree of crosslinking of the high crosslinking density surface layer formed in step S2 satisfies the following relationship: ,in, For a high cross-linking density surface layer, denoted as the initial degree of crosslinking of the pre-cured dielectric polymer layer, and k is the thermally induced crosslinking enhancement factor, which is limited to 1.5 to 2.

2.

6. The manufacturing process for a redistribution structure in an integrated circuit package according to claim 1, characterized in that, The dielectric polymer precursor is photosensitive polyimide or photosensitive polybenzobisazole; the temperature of the first heat treatment process is 100℃ to 120℃, and the treatment time is 180s to 300s.

7. The manufacturing process for a redistribution structure in an integrated circuit package according to claim 1, characterized in that, After performing step S3, the process further includes: step S6, coating the surface of the second metal seed layer with photoresist, and forming a circuit pattern window through exposure and development processes; step S7, performing an electroplating process to fill the circuit pattern window with a metal conductor layer; and step S8, removing the photoresist and etching away the first metal seed layer and the second metal seed layer that are not covered by the metal conductor layer.

8. The manufacturing process for a redistribution structure in an integrated circuit package according to claim 7, characterized in that, The metal conductor layer is made of copper; during step S8, ammonium persulfate solution is used as the etching solution, and the temperature of the etching solution is controlled at 30°C to 40°C.

9. The manufacturing process for a redistribution structure in an integrated circuit package according to claim 1, characterized in that, The duration of the first stage sputtering process is 20 to 40 seconds; The duration of the second-stage sputtering process is 120s to 180s, and the thickness of the second metal seed layer is 100nm to 150nm.

10. The manufacturing process for a redistribution structure in an integrated circuit package according to claim 1, characterized in that, During step S1, the coating thickness of the pre-cured dielectric polymer layer is 5 μm to 10 μm; before step S2, the surface of the pre-cured dielectric polymer layer is activated using oxygen plasma to improve the chemical wettability of the surface.

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