Packaging structure and packaging method

Abstract

The invention discloses a packaging structure and a packaging method, and the packaging structure comprises a chip structure which comprises a plurality of chips stacked in the longitudinal direction, and is provided with a preset heating surface; and the plurality of solder balls are located between the longitudinally adjacent chips so as to realize welding of the adjacent chips, and the melting point of the solder ball close to the preset heating surface is higher than that of the solder ball far away from the preset heating surface. The reliability of the packaging structure can be improved.

Description

Technical Field

[0001] Embodiments of the present invention relate to the field of semiconductor packaging, and in particular to a packaging structure and a packaging method. Background Art

[0002] High Bandwidth Memory (HBM) is used for high-speed data transmission between a Graphics Processing Unit (GPU) and a Central Processing Unit (CPU). The uniqueness of HBM is mainly reflected in stacking and interconnection. HBM vertically stacks multiple Dynamic Random-Access Memories (DRAMs) through the use of advanced packaging technologies (such as Through-Silicon Via (TSV) technology, micro-bump technology, etc.), and is interconnected and packaged with the GPU through an interposer layer, achieving high capacity, high bandwidth, low latency, and low power consumption in a smaller physical space.

[0003] During the HBM stacking process, generally the same chips and the same solder balls are used for multi-layer stacking. As the number of stacked chip layers increases, during the reflow soldering process, the heat received by the solder balls interconnected with the upper-layer chips gradually decreases from the bottom heating plate, thereby affecting the deformation of the solder balls and the soldering quality. Summary of the Invention

[0004] The problem solved by the embodiments of the present invention is to provide a packaging structure and a packaging method, which are beneficial to improving the reliability of the packaging structure.

[0005] To solve the above problems, embodiments of the present invention provide a packaging structure, including: a chip structure including a plurality of chips stacked longitudinally, the chip structure having a preset heating surface; a plurality of solder balls located between longitudinally adjacent chips to achieve welding of adjacent chips, wherein the melting point of the solder balls close to the preset heating surface is higher than the melting point of the solder balls far from the preset heating surface.

[0006] Optionally, the melting point of the solder balls gradually decreases from the one close to the preset heating surface to the one far from the preset heating surface.

[0007] Optionally, the bottom surface of the chip structure is the preset heating surface; the melting point of the solder balls gradually decreases from bottom to top longitudinally.

[0008] Optionally, the melting points of the solder balls between adjacent chips are the same.

[0009] Optionally, the material of the solder balls includes doping elements, the concentration of the doping elements is negatively correlated with the melting point of the solder balls, and the concentration of the doping elements in the solder balls close to the preset heating surface is lower than the concentration of the doping elements in the solder balls far from the preset heating surface.

[0010] Optionally, the doping element includes one or more of lead, bismuth, cadmium, and indium.

[0011] Optionally, the difference between the concentration of the doping element in the solder ball closest to the preset heating surface and the concentration of the doping element in the solder ball farthest from the preset heating surface is -5.5% to -1.5%.

[0012] Optionally, the concentration of the doping element in the solder ball closest to the preset heating surface is 0.5% to 2%; the concentration of the doping element in the solder ball farthest from the preset heating surface is 3.5% to 6%.

[0013] Optionally, the material of the solder ball includes a doping element, and the concentration of the doping element is positively correlated with the melting point of the solder ball. The concentration of the doping element in the solder ball closer to the preset heating surface is higher than the concentration of the doping element in the solder ball farther from the preset heating surface.

[0014] Optionally, the doping element includes one or more of nickel, silver, copper, iron, aluminum, and vanadium.

[0015] Optionally, the difference between the concentration of the doping element in the solder ball closest to the preset heating surface and the concentration of the doping element in the solder ball farthest from the preset heating surface is 1.5% to 5.5%.

[0016] Optionally, the concentration of the doping element in the solder ball closest to the preset heating surface is 3.5% to 6%; the concentration of the doping element in the solder ball farthest from the preset heating surface is 0.5% to 2%.

[0017] Optionally, the material of the solder ball includes tin.

[0018] Optionally, a plurality of chips stacked longitudinally are disposed on a substrate to form a high-bandwidth memory.

[0019] Correspondingly, an embodiment of the present invention further provides a packaging method, including: providing a plurality of chips; using solder balls formed between adjacent chips to implement welding of adjacent chips, stacking the plurality of chips longitudinally to form a chip structure, and the chip structure has a preset heating surface, wherein the melting point of the solder ball closer to the preset heating surface is higher than the melting point of the solder ball farther from the preset heating surface.

[0020] Optionally, in the step of using the solder balls formed between adjacent chips to implement welding of adjacent chips, the melting point of the solder balls gradually decreases from the one closer to the preset heating surface to the one farther from the preset heating surface.

[0021] Optionally, in the step of stacking the plurality of chips longitudinally to form a chip structure with a preset heating surface, the bottom surface of the chip structure is the preset heating surface, and the melting point of the solder balls gradually decreases from bottom to top longitudinally.

[0022] Optionally, in the step of stacking multiple chips longitudinally to form a chip structure with a preset heating surface, the melting points of the solder balls between adjacent chips longitudinally are the same.

[0023] Optionally, in the step of using the solder balls formed between adjacent chips to achieve welding of adjacent chips, the material of the solder balls includes doping elements, and the concentration of the doping elements is negatively correlated with the melting point of the solder balls.

[0024] Optionally, in the step of using the solder balls formed between adjacent chips to achieve welding of adjacent chips, the doping elements include one or more of lead, bismuth, cadmium, and indium.

[0025] Optionally, in the step of using the solder balls formed between adjacent chips to achieve welding of adjacent chips, the material of the solder balls includes doping elements, and the concentration of the doping elements is positively correlated with the melting point of the solder balls.

[0026] Optionally, in the step of using the solder balls formed between adjacent chips to achieve welding of adjacent chips, the doping elements include one or more of nickel, silver, copper, iron, aluminum, and vanadium.

[0027] Optionally, in the step of using the solder balls formed between adjacent chips to achieve welding of adjacent chips and stacking multiple chips longitudinally to form a chip structure, the encapsulation method further includes: performing reflow soldering treatment on the chip structure.

[0028] Optionally, the chip structure is heated by a preset heating surface to perform reflow soldering treatment on the chip structure.

[0029] Optionally, in the step of using the solder balls formed between adjacent chips to achieve welding of adjacent chips and stacking multiple chips longitudinally to form a chip structure, the multiple chips stacked longitudinally are arranged on a substrate to form a high-bandwidth memory.

[0030] Compared with the prior art, the technical solution of the embodiment of the present invention has the following advantages:

[0031] In the packaging structure provided by the embodiments of the present invention, the chip structure includes a plurality of chips stacked longitudinally. The chip structure has a preset heating surface. A plurality of solder balls are located between the longitudinally adjacent chips to achieve the welding of adjacent chips. Among them, the melting point of the solder balls close to the preset heating surface is higher than that of the solder balls far from the preset heating surface. In the embodiments of the present invention, when the chip structure is heated by the preset heating surface, there is a heat difference between the position close to the preset heating surface and the position far from the preset heating surface. Specifically, the temperature of the position close to the preset heating surface is higher, and the temperature of the position far from the preset heating surface is lower. In the embodiments of the present invention, the melting point of the solder balls close to the preset heating surface is higher than that of the solder balls far from the preset heating surface, that is, the solder balls at the position close to the preset heating surface need to be melted at a higher temperature, and the solder balls at the position far from the preset heating surface can be melted at a lower temperature. By adjusting the melting points of the solder balls at the position close to the preset heating surface and the position far from the preset heating surface to conform to the heating law in the chip structure when heated by the preset heating surface, it is beneficial to make the solder balls at each position in the chip structure melt evenly, which is conducive to improving the welding quality and reliability of the solder balls, and at the same time is beneficial to improving the packaging efficiency. Moreover, in the solder ball curing stage after heating the chip structure, the curing times of the solder balls with different melting points are also different, so that the solder balls in the chip structure can be cured step by step, so that the internal stress of the chip structure can be gradually released, which is beneficial to avoiding excessive stress concentration and affecting the connection reliability of the solder balls. All in all, it is beneficial to improve the reliability of the packaging structure.

[0032] In the embodiments of the present invention, the melting point of the solder balls gradually decreases from the position close to the preset heating surface to the position far from the preset heating surface, that is, from the position close to the preset heating surface to the position far from the preset heating surface, the melting point of the solder balls decreases uniformly, further conforming to the heating law in the chip structure when heated by the preset heating surface, which is beneficial to making the solder balls at each position in the chip structure melt more evenly, thus being beneficial to further improving the welding quality and reliability of the solder balls, and at the same time being beneficial to further improving the packaging efficiency.

[0033] In the packaging method provided by the embodiments of the present invention, solder balls formed between adjacent chips are used to realize the welding of adjacent chips, and multiple chips are stacked longitudinally to form a chip structure. The chip structure has a preset heating surface. Among them, the melting point of the solder balls close to the preset heating surface is higher than that of the solder balls far from the preset heating surface. In the embodiments of the present invention, when the chip structure is heated by the preset heating surface, there is a heat difference between the position close to the preset heating surface and the position far from the preset heating surface. Specifically, the temperature at the position close to the preset heating surface is higher, and the temperature at the position far from the preset heating surface is lower. In the embodiments of the present invention, the melting point of the solder balls close to the preset heating surface is higher than that of the solder balls far from the preset heating surface, that is, the solder balls at the position close to the preset heating surface need to be melted at a higher temperature, and the solder balls at the position far from the preset heating surface can be melted at a lower temperature. Then, by adjusting the melting points of the solder balls at the position close to the preset heating surface and the position far from the preset heating surface to conform to the heating law in the chip structure when heated by the preset heating surface, it is beneficial to make the solder balls at each position in the chip structure melt uniformly, which is beneficial to improving the welding quality and reliability of the solder balls, and at the same time beneficial to improving the packaging efficiency. Moreover, in the curing stage of the solder balls after heating the chip structure, the curing times of the solder balls with different melting points are also different, so that the solder balls in the chip structure can be cured step by step, so that the stress inside the chip structure can be released step by step, which is beneficial to avoiding excessive stress concentration and affecting the connection reliability of the solder balls. In summary, all of the above are beneficial to improving the reliability of the packaging structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 is a schematic structural diagram corresponding to each step in a packaging method;

[0035] Figure 2 is a schematic structural diagram corresponding to an embodiment of the packaging structure of the present invention;

[0036] Figures 3 to 5 is a schematic structural diagram corresponding to each step in an embodiment of the packaging method of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0037] At present, the reliability of the packaging structure needs to be improved. The reason why the reliability of the packaging structure needs to be improved is analyzed in combination with a packaging structure.

[0038] Figure 1 is a schematic structural diagram corresponding to each step in a packaging method.

[0039] Refer to Figure 1 , a chip structure 21 is provided. The chip structure 21 includes longitudinally (such as Figure 1A plurality of chips 20 stacked in the Z direction as shown in the figure, solder balls 30 are formed between adjacent chip structures 21, and adjacent chip structures 21 are welded to each other through the solder balls 30; the chip structure 21 is heated through the bottom of the chip structure 21 to perform reflow soldering on the chip structure 21.

[0040] In the existing packaging structure, as the number of stacked chips 20 increases, during the reflow soldering process, the temperature transferred to the upper-layer chips 20 will gradually decrease, and the time for heat to be transferred to the upper-layer chips 20 will gradually increase. As a result, during the heating process, due to the temperature difference in the heat received by the solder balls 30 of different layers, the solder states are out of sync, affecting the welding quality of the solder balls 30, thereby affecting the stability of the electrical and mechanical connections between the chips 20 and 20. Specifically, the solder balls 30 farther away from the heating surface receive less heat, and the time required for the solder balls to melt is longer. As a result, the reflow soldering effect of the solder balls 30 far away from the heating surface is poor, leading to unstable welding of the upper-layer chips 20 and affecting the reliability of the packaging structure. And due to the temperature difference in the heat received by the solder balls 30 of different layers, the solder balls 30 cannot melt simultaneously. To ensure the welding quality of the upper-layer solder balls 30, it is necessary to increase the heating time and heating temperature, which will also lead to an increase in the deformation amount of the lower-layer solder balls and an increase in the uncertainty during the packaging process, thereby affecting the packaging efficiency and product yield.

[0041] To solve the above technical problems, the present invention provides a packaging structure, including: a chip structure, including a plurality of chips stacked longitudinally, the chip structure having a preset heating surface; a plurality of solder balls located between longitudinally adjacent chips to realize the welding of adjacent chips, wherein the melting point of the solder balls close to the preset heating surface is higher than the melting point of the solder balls far from the preset heating surface.

[0042] In the embodiments of the present invention, when heating the chip structure by a preset heating surface, there is a heat difference between the position close to the preset heating surface and the position far from the preset heating surface. Specifically, the temperature at the position close to the preset heating surface is relatively high, and the temperature at the position far from the preset heating surface is relatively low. In the embodiments of the present invention, the melting point of the solder balls close to the preset heating surface is higher than that of the solder balls far from the preset heating surface, that is, the solder balls at the position close to the preset heating surface need to be melted at a higher temperature, and the solder balls at the position far from the preset heating surface can be melted at a lower temperature. By adjusting the melting points of the solder balls at the position close to the preset heating surface and the position far from the preset heating surface to conform to the heating law in the chip structure when heated by the preset heating surface, it is beneficial to uniformly melt the solder balls at various positions in the chip structure, thereby facilitating the improvement of the welding quality and reliability of the solder balls, and at the same time facilitating the improvement of the packaging efficiency. Moreover, during the curing stage of the solder balls after heating the chip structure, the curing times of the solder balls with different melting points are also different, enabling the solder balls in the chip structure to be cured step by step, so that the stress inside the chip structure can be gradually released, thereby facilitating the avoidance of excessive stress concentration and affecting the connection reliability of the solder balls. In summary, all of the above are beneficial to improving the reliability of the packaging structure.

[0043] In order to make the above-mentioned objects, features, and advantages of the embodiments of the present invention more obvious and understandable, the following will describe in detail the specific embodiments of the present invention with reference to the accompanying drawings.

[0044] Figure 2 It is a schematic structural diagram corresponding to an embodiment of the packaging structure of the present invention.

[0045] Reference Figure 2 shows that the packaging structure includes: a chip structure 210, including a plurality of chips 200 stacked longitudinally (such as Figure 2 shown in the Z direction in

[0046] ), and the chip structure 210 has a preset heating surface 210t; a plurality of solder balls 300, located between adjacent chips 200 longitudinally to realize the welding of adjacent chips 200, wherein the melting point of the solder balls 300 close to the preset heating surface 210t is higher than that of the solder balls 300 far from the preset heating surface 210t.

[0047] The chips 200 are used to meet the performance requirements of the packaging structure. Specifically, different functional chips 200 can be selected according to the performance requirements of the packaging structure.

[0048] In this embodiment, the packaging structure further includes: a substrate 100, and a plurality of chips 200 stacked longitudinally are welded to the substrate 100.

[0049] The substrate 100 provides a process operation basis for realizing the soldering of the chip 200.

[0050] In this embodiment, the substrate 100 is an interposer.

[0051] The interposer is used to interconnect and package multiple stacked chips 200, for electrically leading out the multiple stacked chips 200, and realizing the electrical connection between the multiple stacked chips 200 and the outside.

[0052] As an example, in this embodiment, multiple chips 200 stacked longitudinally are arranged on the substrate 100 to form a High Bandwidth Memory (HBM) structure. By adopting the HBM structure, it is beneficial to meet the requirements for higher information transmission speed.

[0053] Among them, the multiple chips 200 stacked longitudinally include a logic chip at the bottommost layer and memory chips stacked on the logic chip. The number of memory chips can be one or more. In this embodiment, the number of memory chips is taken as eight as an example for illustration. In other embodiments, the number of memory chips can also be other numbers.

[0054] As an example, in this embodiment, the HBM structure formed by multiple chips 200 stacked longitudinally is interconnected with external chips through an interposer. Specifically, the external chips can be a central processing unit (CPU) chip, a graphics processing unit (GPU) chip, or a system on chip (SoC).

[0055] In this embodiment, the chip structure 210 has a preset heating surface 210t.

[0056] The preset heating surface 210t refers to the heating surface during the reflow soldering process in the packaging process, that is, by heating the preset heating surface 210t, the temperature of the chip structure 210 is increased to achieve the reflow soldering of the solder balls.

[0057] As an example, in this embodiment, the bottom surface of the chip structure 210 is the preset heating surface 210t.

[0058] The solder balls 300 are used to solder adjacent chips 200 to achieve the electrical connection between adjacent chips 200.

[0059] In this embodiment, when heating the chip structure 210 from the preset heating surface 210t, there is a heat difference between the position close to the preset heating surface 210t and the position far from the preset heating surface 210t. Specifically, the position close to the preset heating surface 210t receives more heat, so the solder ball temperature at the position close to the preset heating surface 210t is higher. The position far from the preset heating surface 210t receives less heat, so the solder ball temperature at the position far from the preset heating surface 210t is lower. In this embodiment, the melting point of the solder ball 300 close to the preset heating surface 210t is higher than that of the solder ball 300 far from the preset heating surface 210t. That is, the solder ball 300 at the position close to the preset heating surface 210t needs to be melted at a higher temperature, and the solder ball 300 at the position far from the preset heating surface 210t can be melted at a lower temperature. By adjusting the melting points of the solder balls 300 at the position close to the preset heating surface 210t and the position far from the preset heating surface 210t to conform to the heat conduction law in the chip structure 210 when heated by the preset heating surface 210t, it is beneficial to uniformly melt the solder balls 300 at various positions in the chip structure 210, thereby facilitating the improvement of the welding quality and reliability of the solder balls 300, and at the same time facilitating the improvement of the packaging efficiency. Moreover, during the curing stage of the solder balls 300 after heating the chip structure 210, the cooling and curing times of the solder balls 300 with different melting points are also different, enabling the solder balls 300 in the chip structure 210 to be cured step by step, so that the stress inside the chip structure 210 can be gradually released, thus facilitating the avoidance of excessive stress concentration and affecting the connection reliability of the solder balls 300. In summary, all of the above are beneficial to improving the reliability of the packaging structure.

[0060] In this embodiment, the material of the solder ball 300 includes tin.

[0061] In this embodiment, the material of the solder ball 300 includes doping elements, and the concentration of the doping elements is negatively correlated with the melting point of the solder ball 300. The concentration of the doping elements in the solder ball 300 close to the preset heating surface 210t is lower than that in the solder ball 300 far from the preset heating surface 210t.

[0062] Among them, the concentration of the doping elements being negatively correlated with the melting point of the solder ball 300 means that for some doping elements, such as lead, bismuth, cadmium, and indium, the higher the concentration of the doping elements in the solder ball 300, the lower the melting point of the solder ball 300, and the lower the concentration of the doping elements in the solder ball 300, the higher the melting point of the solder ball 300.

[0063] The concentration of the doping element in the solder ball 300 close to the preset heating surface 210t is lower than that in the solder ball 300 far from the preset heating surface 210t, so that the melting point of the solder ball 300 close to the preset heating surface 210t can be higher than that of the solder ball 300 far from the preset heating surface 210t. In this embodiment, by adjusting the concentration of the doping element in different solder balls 300, the melting point of different solder balls 300 can be adjusted, making it easy to adjust the melting point of the solder ball 300.

[0064] In this embodiment, the doping element includes one or more of lead, bismuth, cadmium and indium.

[0065] The melting points of elements such as lead, bismuth, cadmium and indium are lower than that of tin. Incorporating one or more of lead, bismuth, cadmium and indium into the solder ball 300 can reduce the melting point of the solder ball 300, and the higher the doping concentration, the lower the melting point of the solder ball 300.

[0066] In this embodiment, the difference between the concentration of the doping element in the solder ball 300 closest to the preset heating surface 210t and the concentration of the doping element in the solder ball 300 farthest from the preset heating surface 210t is -5.5% to -1.5%.

[0067] If the difference between the concentration of the doping element in the solder ball 300 closest to the preset heating surface 210t and the concentration of the doping element in the solder ball 300 farthest from the preset heating surface 210t is -5.5% to -1.5%, then the difference between the concentration of the doping element in the solder ball 300 closest to the preset heating surface 210t and the concentration of the doping element in the solder ball 300 farthest from the preset heating surface 210t will not be too large, that is, the difference between the melting points of the solder ball 300 closest to the preset heating surface 210t and the solder ball 300 farthest from the preset heating surface 210t will not be too large. When the chip structure 210 is heated by the preset heating surface 210t, the melting time points of the solder ball 300 close to the preset heating surface 210t and the solder ball 300 far from the preset heating surface 210t are closer, which is beneficial to making the solder balls 300 at various positions in the chip structure 210 melt more uniformly. And ensuring that there is an appropriate concentration difference between the concentration of the doping element in the solder ball 300 closest to the preset heating surface 210t and the concentration of the doping element in the solder ball 300 farthest from the preset heating surface 210t, that is, there is an appropriate gap between the melting points of the solder ball 300 closest to the preset heating surface 210t and the solder ball 300 farthest from the preset heating surface 210t, is beneficial to ensuring that the chip structure 210 in this embodiment conforms to the heat conduction law in the chip structure 210 when heated by the preset heating surface 210t, thus facilitating the uniform melting of the solder balls 300 at various positions in the chip structure 210.

[0068] In this embodiment, the concentration of the doping element in the solder ball 300 closest to the preset heating surface 210t is 0.5% to 2%.

[0069] The concentration of the doping element in the solder ball 300 closest to the preset heating surface 210t is 0.5% to 2%, so that the solder ball 300 closest to the preset heating surface 210t has a relatively high melting point and is not likely to cause too large a melting point difference from the solder ball 300 far from the preset heating surface 210t, enabling the solder balls 300 at various positions in the chip structure 210 to melt evenly.

[0070] In this embodiment, the concentration of the doping element in the solder ball 300 farthest from the preset heating surface 210t is 3.5% to 6%.

[0071] The concentration of the doping element in the solder ball 300 farthest from the preset heating surface 210t is 3.5% to 6%, so that the solder ball 300 farthest from the preset heating surface 210t has a relatively low melting point and is not likely to cause too large a melting point difference from the solder ball 300 close to the preset heating surface 210t, enabling the solder balls 300 at various positions in the chip structure 210 to melt evenly.

[0072] In other embodiments, the concentration of the doping element is positively correlated with the melting point of the solder ball, and the concentration of the doping element in the solder ball close to the preset heating surface is higher than that in the solder ball far from the preset heating surface.

[0073] Wherein, the concentration of the doping element being positively correlated with the melting point of the solder ball means that for some doping elements, such as nickel, silver, copper, iron, aluminum, and vanadium, the higher the concentration of the doping element in the solder ball, the higher the melting point of the solder ball, and the lower the concentration of the doping element in the solder ball, the lower the melting point of the solder ball.

[0074] The concentration of the doping element in the solder ball close to the preset heating surface is higher than that in the solder ball far from the preset heating surface, so that the melting point of the solder ball close to the preset heating surface can be higher than that of the solder ball far from the preset heating surface. By adjusting the concentration of the doping element in different solder balls, the melting point of different solder balls can be adjusted, making it easy to adjust the melting point of the solder balls.

[0075] The doping element includes one or more of nickel, silver, copper, iron, aluminum, and vanadium.

[0076] The melting points of elements such as nickel, silver, copper, iron, aluminum, and vanadium are higher than that of tin. Incorporating one or more of nickel, silver, copper, iron, aluminum, and vanadium into the solder ball can increase the melting point of the solder ball, and the higher the doping concentration, the higher the melting point of the solder ball.

[0077] In one embodiment, the difference between the concentration of the doping element in the solder ball closest to the preset heating surface and the concentration of the doping element in the solder ball farthest from the preset heating surface is 1.5% to 5.5%.

[0078] If the difference in the concentration of the doping element between the solder ball closest to the preset heating surface and the solder ball farthest from the preset heating surface is 1.5% to 5.5%, then the difference in the concentration of the doping element between the solder ball closest to the preset heating surface and the solder ball farthest from the preset heating surface will not be too large, that is, the difference in the melting point between the solder ball closest to the preset heating surface and the solder ball farthest from the preset heating surface will not be too large. When the chip structure is heated by the preset heating surface, the melting time points of the solder balls close to the preset heating surface and the solder balls far from the preset heating surface are closer, which is conducive to making the solder balls at various positions in the chip structure melt more uniformly, and ensuring that there is an appropriate concentration difference between the concentration of the doping element in the solder ball closest to the preset heating surface and the concentration of the doping element in the solder ball farthest from the preset heating surface, that is, there is an appropriate gap between the melting points of the solder ball closest to the preset heating surface and the solder ball farthest from the preset heating surface, which is conducive to ensuring that the chip structure in this embodiment conforms to the heat conduction law in the chip structure when heated by the preset heating surface, thereby facilitating the uniform melting of the solder balls at various positions in the chip structure.

[0079] In one embodiment, the concentration of the doping element in the solder ball closest to the preset heating surface is 3.5% to 6%.

[0080] The concentration of the doping element in the solder ball closest to the preset heating surface is 3.5% to 6%, which makes the solder ball closest to the preset heating surface have a higher melting point and is not likely to cause too large a melting point difference from the solder ball far from the preset heating surface, so that the solder balls at various positions in the chip structure melt uniformly.

[0081] In one embodiment, the concentration of the doping element in the solder ball farthest from the preset heating surface is 0.5% to 2%.

[0082] The concentration of the doping element in the solder ball farthest from the preset heating surface is 0.5% to 2%, which makes the solder ball farthest from the preset heating surface have a lower melting point and is not likely to cause too large a melting point difference from the solder ball close to the preset heating surface, so that the solder balls at various positions in the chip structure melt uniformly.

[0083] In this embodiment, the melting point of the solder ball 300 gradually decreases from the position close to the preset heating surface 210t to the position far from the preset heating surface 210t.

[0084] The melting point of the solder balls 300 gradually decreases from near the preset heating surface 210t to far from the preset heating surface 210t, that is, from the position near the preset heating surface 210t to the position far from the preset heating surface 210t, the melting point of the solder balls 300 decreases uniformly, further conforming to the heat conduction law in the chip structure 210 when heated by the preset heating surface 210t, which is beneficial to making the solder balls 300 at each position in the chip structure 210 melt more uniformly, thereby being beneficial to further improving the welding quality and reliability of the solder balls 300, and at the same time being beneficial to further improving the packaging efficiency.

[0085] Correspondingly, in this embodiment, the melting point of the solder balls 300 gradually decreases from bottom to top in the longitudinal direction.

[0086] That is, when performing reflow soldering on the chip structure 210, heating starts from the bottom of the chip structure 210, and the heat is transferred from bottom to top. The melting point of the solder balls 300 gradually decreasing from bottom to top in the longitudinal direction conforms to this heat conduction law, making the solder balls 300 at each position in the chip structure 210 melt more uniformly.

[0087] In this embodiment, the melting points of the solder balls 300 between adjacent chips 200 are the same.

[0088] The melting points of the solder balls 300 between adjacent chips 200 are the same, that is, the melting points of the solder balls 300 in the same layer are the same, which is beneficial to making the solder balls 300 in the same layer melt more precisely at the same time, thereby being beneficial to the welding quality between adjacent chips 200 and being beneficial to ensuring the welding strength between adjacent chips 200.

[0089] Correspondingly, in this embodiment, the solder balls 300 are also formed between the lowermost chip 200 and the substrate 100 to realize the electrical connection between the chip 200 and the substrate 100.

[0090] Figures 3 to 5 It is a schematic structural diagram corresponding to each step in an embodiment of the packaging method of the present invention.

[0091] Refer to Figure 3 , and provide a plurality of chips 200.

[0092] The chips 200 are used to meet the performance requirements of the packaging structure. Specifically, different functional chips 200 can be selected according to the performance requirements of the packaging structure.

[0093] Refer to Figure 4 , and use the solder balls 300 formed between adjacent chips 200 to realize the welding of adjacent chips 200, and arrange the plurality of chips 200 longitudinally (such as Figure 4Stacked in the Z direction (as shown in the figure) to form a chip structure 210, the chip structure 210 has a preset heating surface 210t. Among them, the melting point of the solder balls 300 close to the preset heating surface 210t is higher than that of the solder balls 300 far from the preset heating surface 210t.

[0094] In this embodiment, multiple vertically stacked chips 200 are electrically connected to each other, that is, multiple vertically stacked chips are electrically connected to each other through Through-Silicon Via (TSV) technology and solder balls.

[0095] Specifically, in this embodiment, in the step of using the solder balls 300 formed between adjacent chips 200 to realize the welding of adjacent chips 200, multiple chips 200 are stacked longitudinally on the substrate 100 to form a chip structure 210.

[0096] The substrate 100 is used to provide a process operation basis for realizing the welding of the chips 200.

[0097] In this embodiment, the substrate 100 is an Interposer.

[0098] An Interposer is used to interconnect and package multiple stacked chips 200, for electrically leading out the multiple stacked chips 200, and realizing the electrical connection between the multiple stacked chips 200 and the outside.

[0099] Correspondingly, in this embodiment, solder balls 300 are also formed between the bottommost chip 200 and the substrate 100 to realize the electrical connection between the chip 200 and the substrate 100.

[0100] As an example, in this embodiment, multiple vertically stacked chips 200 are arranged on a substrate to form a High Bandwidth Memory (HBM) structure. By adopting the HBM structure, it is beneficial to meet the requirements for higher information transmission speeds.

[0101] Among them, multiple vertically stacked chips 200 include a logic chip at the bottommost layer and memory chips stacked on the logic chip. The number of memory chips can be one or more. In this embodiment, the number of memory chips is taken as eight as an example for illustration. In other embodiments, the number of memory chips can also be other numbers.

[0102] As an example, in this embodiment, the HBM structure composed of multiple chips 200 stacked longitudinally is interconnected with external chips through an interposer. Specifically, the external chips can be central processing unit (CPU) chips, graphics processing unit (GPU) chips, or system on chip (SoC).

[0103] In this embodiment, the chip structure 210 has a preset heating surface 210t.

[0104] The preset heating surface 210t refers to the heating surface during subsequent reflow soldering processing, that is, the temperature of the chip structure 210 is increased by heating the preset heating surface 210t to achieve solder ball reflow soldering.

[0105] As an example, in this embodiment, the bottom surface of the chip structure 210 is the preset heating surface 210t.

[0106] The solder balls 300 are used to weld adjacent chips 200 to achieve electrical connection of adjacent chips 200.

[0107] In this embodiment, when heating the chip structure 210 from the preset heating surface 210t, there is a heat difference between the position close to the preset heating surface 210t and the position far from the preset heating surface 210t. Specifically, the position close to the preset heating surface 210t receives more heat, so the solder ball temperature at the position close to the preset heating surface 210t is higher. The position far from the preset heating surface 210t receives less heat, so the solder ball temperature at the position far from the preset heating surface 210t is lower. In this embodiment, the melting point of the solder ball 300 close to the preset heating surface 210t is higher than that of the solder ball 300 far from the preset heating surface 210t. That is, the solder ball 300 at the position close to the preset heating surface 210t needs to be melted at a higher temperature, and the solder ball 300 at the position far from the preset heating surface 210t can be melted at a lower temperature. By adjusting the melting points of the solder balls 300 at the position close to the preset heating surface 210t and the position far from the preset heating surface 210t to conform to the heat conduction law in the chip structure 210 when heated by the preset heating surface 210t, it is beneficial to uniformly melt the solder balls 300 at various positions in the chip structure 210, thereby facilitating the improvement of the welding quality and reliability of the solder balls 300, and at the same time facilitating the improvement of the packaging efficiency. Moreover, during the curing stage of the solder balls 300 after heating the chip structure 210, the cooling and curing times of the solder balls 300 with different melting points are also different, enabling the solder balls 300 in the chip structure 210 to be gradually cured, so that the stress inside the chip structure 210 can be gradually released, thus facilitating the avoidance of excessive stress concentration and affecting the connection reliability of the solder balls 300. In summary, all of the above are beneficial to improving the reliability of the packaging structure.

[0108] In this embodiment, in the step of using the solder balls 300 formed between adjacent chips 200 to realize the welding of adjacent chips 200, the material of the solder balls 300 includes tin.

[0109] Using tin to form the solder balls 300 is beneficial to obtaining solder balls 300 with better electrical connection performance.

[0110] In this embodiment, in the step of using the solder balls 300 formed between adjacent chips 200 to realize the welding of adjacent chips 200, the material of the solder balls 300 includes doping elements, and the concentration of the doping elements is negatively correlated with the melting point of the solder balls 300. The concentration of the doping elements in the solder balls 300 close to the preset heating surface 210t is lower than that in the solder balls 300 far from the preset heating surface 210t.

[0111] Among them, the concentration of the doping elements being negatively correlated with the melting point of the solder balls 300 means that for some doping elements, such as lead, bismuth, cadmium, and indium, the higher the concentration of the doping elements in the solder balls 300, the lower the melting point of the solder balls 300, and the lower the concentration of the doping elements in the solder balls 300, the higher the melting point of the solder balls 300.

[0112] The concentration of the doping element in the solder ball 300 close to the preset heating surface 210t is lower than that in the solder ball 300 far from the preset heating surface 210t, so that the melting point of the solder ball 300 close to the preset heating surface 210t can be higher than that of the solder ball 300 far from the preset heating surface 210t. In this embodiment, by adjusting the concentration of the doping element in different solder balls 300, the melting point of different solder balls 300 can be adjusted, making it easy to adjust the melting point of the solder ball 300.

[0113] In this embodiment, in the step of using the solder ball 300 formed between adjacent chips 200 to realize the welding of adjacent chips 200, the doping element includes one or more of lead, bismuth, cadmium and indium.

[0114] The melting points of elements such as lead, bismuth, cadmium and indium are lower than that of tin. Incorporating one or more of lead, bismuth, cadmium and indium into the solder ball 300 can reduce the melting point of the solder ball 300, and the higher the doping concentration, the lower the melting point of the solder ball 300.

[0115] In this embodiment, in the step of using the solder ball 300 formed between adjacent chips 200 to realize the welding of adjacent chips 200, the difference between the concentration of the doping element in the solder ball 300 closest to the preset heating surface 210t and the concentration of the doping element in the solder ball 300 farthest from the preset heating surface 210t is -5.5% to -1.5%.

[0116] If the difference in the concentration of the doping element in the solder ball 300 closest to the preset heating surface 210t and the concentration of the doping element in the solder ball 300 farthest from the preset heating surface 210t is -5.5% to -1.5%, then the difference in the concentration of the doping element in the solder ball 300 closest to the preset heating surface 210t and the concentration of the doping element in the solder ball 300 farthest from the preset heating surface 210t will not be too large, that is, the difference in the melting point between the solder ball 300 closest to the preset heating surface 210t and the solder ball 300 farthest from the preset heating surface 210t will not be too large. When the chip structure 210 is heated by the preset heating surface 210t, the melting time points of the solder ball 300 close to the preset heating surface 210t and the solder ball 300 far from the preset heating surface 210t are closer, which is beneficial to making the solder balls 300 at various positions in the chip structure 210 melt more uniformly, and ensuring that there is an appropriate concentration difference between the concentration of the doping element in the solder ball 300 closest to the preset heating surface 210t and the concentration of the doping element in the solder ball 300 farthest from the preset heating surface 210t, that is, there is an appropriate gap between the melting points of the solder ball 300 closest to the preset heating surface 210t and the solder ball 300 farthest from the preset heating surface 210t, which is beneficial to ensuring that the chip structure 210 of this embodiment conforms to the heat conduction law in the chip structure 210 when heated by the preset heating surface 210t, and thus is beneficial to making the solder balls 300 at various positions in the chip structure 210 melt uniformly.

[0117] In this embodiment, in the step of using the solder ball 300 formed between adjacent chips 200 to realize the welding of adjacent chips 200, the concentration of the doping element in the solder ball 300 closest to the preset heating surface 210t is 0.5% to 2%.

[0118] The concentration of the doping element in the solder ball 300 closest to the preset heating surface 210t being 0.5% to 2% makes the solder ball 300 closest to the preset heating surface 210t have a higher melting point and is not likely to cause too large a melting point difference from the solder ball 300 far from the preset heating surface 210t, making the solder balls 300 at various positions in the chip structure 210 melt uniformly.

[0119] In this embodiment, in the step of using the solder ball 300 formed between adjacent chips 200 to realize the welding of adjacent chips 200, the concentration of the doping element in the solder ball 300 farthest from the preset heating surface 210t is 3.5% to 6%.

[0120] The concentration of the doping element in the solder ball 300 farthest from the preset heating surface 210t being 3.5% to 6% makes the solder ball 300 farthest from the preset heating surface 210t have a lower melting point and is not likely to cause too large a melting point difference from the solder ball 300 close to the preset heating surface 210t, making the solder balls 300 at various positions in the chip structure 210 melt uniformly.

[0121] In other embodiments, in the step of realizing the welding of adjacent chips by using solder balls formed between adjacent chips, the concentration of the doping element is positively correlated with the melting point of the solder ball, and the concentration of the doping element in the solder ball closer to the preset heating surface is higher than that in the solder ball farther from the preset heating surface.

[0122] Among them, the concentration of the doping element being positively correlated with the melting point of the solder ball means that for some doping elements, such as nickel, silver, copper, iron, aluminum, and vanadium, the higher the concentration of the doping element in the solder ball, the higher the melting point of the solder ball, and the lower the concentration of the doping element in the solder ball, the lower the melting point of the solder ball.

[0123] The concentration of the doping element in the solder ball closer to the preset heating surface is higher than that in the solder ball farther from the preset heating surface, so that the melting point of the solder ball closer to the preset heating surface can be higher than that of the solder ball farther from the preset heating surface. By adjusting the concentration of the doping element in different solder balls, the melting point of different solder balls can be adjusted, making it easy to realize the adjustment of the melting point of the solder ball.

[0124] In the step of realizing the welding of adjacent chips by using solder balls formed between adjacent chips, the doping element includes one or more of nickel, silver, copper, iron, aluminum, and vanadium.

[0125] The melting points of elements such as nickel, silver, copper, iron, aluminum, and vanadium are higher than that of tin. Incorporating one or more of nickel, silver, copper, iron, aluminum, and vanadium into the solder ball can increase the melting point of the solder ball, and the higher the doping concentration, the higher the melting point of the solder ball.

[0126] In one embodiment, in the step of realizing the welding of adjacent chips by using solder balls formed between adjacent chips, the difference between the concentration of the doping element in the solder ball closest to the preset heating surface and the concentration of the doping element in the solder ball farthest from the preset heating surface is 1.5% to 5.5%.

[0127] If the difference in the concentration of the doping element between the solder ball closest to the preset heating surface and the solder ball farthest from the preset heating surface is 1.5% to 5.5%, then the difference in the concentration of the doping element between the solder ball closest to the preset heating surface and the solder ball farthest from the preset heating surface will not be too large, that is, the difference in the melting point between the solder ball closest to the preset heating surface and the solder ball farthest from the preset heating surface will not be too large. When the chip structure is heated by the preset heating surface, the melting time points of the solder balls close to the preset heating surface and the solder balls far from the preset heating surface are closer, which is beneficial to making the solder balls at various positions in the chip structure melt more uniformly, and ensuring that there is an appropriate concentration difference between the concentration of the doping element in the solder ball closest to the preset heating surface and the concentration of the doping element in the solder ball farthest from the preset heating surface, that is, there is an appropriate gap between the melting points of the solder ball closest to the preset heating surface and the solder ball farthest from the preset heating surface, which is beneficial to ensuring that the chip structure of this embodiment conforms to the heat conduction law in the chip structure when heated by the preset heating surface, thereby facilitating the uniform melting of the solder balls at various positions in the chip structure.

[0128] In one embodiment, in the step of using the solder balls formed between adjacent chips to realize the welding of adjacent chips, the concentration of the doping element in the solder ball closest to the preset heating surface is 3.5% to 6%.

[0129] The concentration of the doping element in the solder ball closest to the preset heating surface is 3.5% to 6%, which makes the solder ball closest to the preset heating surface have a higher melting point and is not likely to cause too large a melting point difference from the solder balls far from the preset heating surface, so that the solder balls at various positions in the chip structure melt uniformly.

[0130] In one embodiment, in the step of using the solder balls formed between adjacent chips to realize the welding of adjacent chips, the concentration of the doping element in the solder ball farthest from the preset heating surface is 0.5% to 2%.

[0131] The concentration of the doping element in the solder ball farthest from the preset heating surface is 0.5% to 2%, which makes the solder ball farthest from the preset heating surface have a lower melting point and is not likely to cause too large a melting point difference from the solder balls close to the preset heating surface, so that the solder balls at various positions in the chip structure melt uniformly.

[0132] In this embodiment, in the step of using the solder balls 300 formed between adjacent chips 200 to realize the welding of adjacent chips 200, the melting point of the solder balls 300 gradually decreases from the position close to the preset heating surface 210t to the position far from the preset heating surface 210t.

[0133] The melting point of the solder balls 300 gradually decreases from the position close to the preset heating surface 210t to the position far from the preset heating surface 210t, that is, from the position close to the preset heating surface 210t to the position far from the preset heating surface 210t, the melting point of the solder balls 300 decreases uniformly, further conforming to the heat conduction law in the chip structure 210 when heated by the preset heating surface 210t, which is beneficial to making the solder balls 300 at various positions in the chip structure 210 melt more uniformly, thereby being beneficial to further improving the welding quality and reliability of the solder balls 300, and at the same time being beneficial to further improving the packaging efficiency.

[0134] Correspondingly, in this embodiment, the melting point of the solder balls 300 gradually decreases from bottom to top in the longitudinal direction.

[0135] That is, when the chip structure 210 is subsequently subjected to reflow soldering treatment, heating starts from the bottom of the chip structure 210, and the heat is transferred from bottom to top. The fact that the melting point of the solder balls 300 gradually decreases from bottom to top in the longitudinal direction conforms to this heat conduction law, making the solder balls 300 at various positions in the chip structure 210 melt more uniformly.

[0136] In this embodiment, in the step of using the solder balls 300 formed between adjacent chips 200 to realize the welding of adjacent chips 200, the melting points of the solder balls 300 between adjacent chips 200 are the same.

[0137] The melting points of the solder balls 300 between adjacent chips 200 are the same, that is, the melting points of the solder balls 300 in the same layer are the same, which is beneficial to making the solder balls 300 in the same layer melt more precisely at the same time, thereby being beneficial to the welding quality between adjacent chips 200 and being beneficial to ensuring the welding strength between adjacent chips 200.

[0138] Reference Figure 5 , using the solder balls 300 formed between adjacent chips 200 to realize the welding of adjacent chips 200, after stacking multiple chips 200 longitudinally to form the chip structure 210, the packaging method further includes: performing a reflow soldering treatment on the chip structure 210.

[0139] Performing a reflow soldering treatment on the chip structure 210 causes the solder balls 300 to melt and form a firm connection with adjacent chips 200.

[0140] Specifically, in this embodiment, the chip structure 210 is heated by the preset heating surface 210t to perform a reflow soldering treatment on the chip structure 210.

[0141] The heating block is used to heat the chip structure 210 by the preset heating surface 210t, so that the solder balls 300 in the chip structure 210 are melted and connected to the adjacent chip 200, and then cured to form the final solder joints. Specifically, in this embodiment, the melting point of the solder balls 300 close to the preset heating surface 210t is higher than that of the solder balls 300 far from the preset heating surface 210t. Then, the chip structure 210 is heated by the preset heating surface 210t. After the chip structure 210 is subjected to reflow soldering, the formation of the solder joints at various parts of the chip structure 210 is relatively consistent.

[0142] Although the present invention is disclosed as above, the present invention is not limited thereto. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention should be subject to the scope defined by the claims.

Claims

1. A packaging structure, characterized in that: include: A chip structure, comprising a plurality of chips stacked in a longitudinal direction, wherein the chip structure has a preset heating surface; A plurality of solder balls are located between longitudinally adjacent chips to realize welding of adjacent chips, wherein the melting point of the solder balls close to the preset heating surface is higher than the melting point of the solder balls far from the preset heating surface.

2. The packaging structure according to claim 1, characterized in that: The melting point of the solder ball gradually decreases from being close to the preset heating surface to being far away from the preset heating surface.

3. The packaging structure according to claim 2, characterized in that: The bottom surface of the chip structure is the preset heating surface; The melting point of the solder ball gradually decreases from bottom to top along the longitudinal direction.

4. The packaging structure according to claim 3, characterized in that: The melting points of the solder balls between adjacent chips are the same.

5. The packaging structure according to any one of claims 1 to 4, characterized in that: The material of the solder ball includes a doping element, the concentration of the doping element is negatively correlated with the melting point of the solder ball, and the concentration of the doping element in the solder ball close to the preset heating surface is lower than the concentration of the doping element in the solder ball far from the preset heating surface.

6. The packaging structure according to claim 5, characterized in that: The doping element includes one or more of lead, bismuth, cadmium and indium.

7. The packaging structure according to claim 5, characterized in that: The difference between the concentration of the doping element in the solder ball closest to the preset heating surface and the concentration of the doping element in the solder ball farthest from the preset heating surface is -5.5% to -1.5%.

8. The packaging structure according to claim 5, characterized in that: The concentration of the doping element in the solder ball closest to the preset heating surface is 0.5% to 2%; The concentration of the doping element in the solder ball farthest from the preset heating surface is 3.5% to 6%.

9. The packaging structure according to any one of claims 1 to 4, characterized in that: The material of the solder ball includes a doping element, the concentration of the doping element is positively correlated with the melting point of the solder ball, and the concentration of the doping element in the solder ball close to the preset heating surface is higher than the concentration of the doping element in the solder ball far from the preset heating surface.

10. The packaging structure according to claim 9, characterized in that: The doping element includes one or more of nickel, silver, copper, iron, aluminum and vanadium.

11. The packaging structure according to claim 9, characterized in that: The difference between the concentration of the doping element in the solder ball closest to the preset heating surface and the concentration of the doping element in the solder ball farthest from the preset heating surface is 1.5% to 5.5%.

12. The packaging structure according to claim 9, characterized in that: The concentration of the doping element in the solder ball closest to the preset heating surface is 3.5% to 6%; The concentration of the doping element in the solder ball farthest from the preset heating surface is 0.5% to 2%.

13. The packaging structure according to claim 1, characterized in that: The material of the solder ball includes tin.

14. The packaging structure according to claim 1, wherein: A plurality of the chips stacked in a longitudinal direction are arranged on a substrate to form a high bandwidth memory.

15. A packaging method, characterized in that: include: Provide multiple chips; The adjacent chips are welded by using solder balls formed between the adjacent chips, and a plurality of the chips are stacked longitudinally to form a chip structure having a preset heating surface, wherein the melting point of the solder balls close to the preset heating surface is higher than the melting point of the solder balls far from the preset heating surface.

16. The packaging method according to claim 15, characterized in that: In the step of welding adjacent chips by using solder balls formed between adjacent chips, the melting point of the solder balls gradually decreases from being close to the preset heating surface to being far away from the preset heating surface.

17. The packaging method according to claim 16, characterized in that: In the step of stacking a plurality of the chips longitudinally to form a chip structure, wherein the chip structure has a preset heating surface, the bottom surface of the chip structure is the preset heating surface, and the melting point of the solder ball gradually decreases from bottom to top along the longitudinal direction.

18. The packaging method according to claim 17, characterized in that: In the step of stacking a plurality of the chips longitudinally to form a chip structure having a preset heating surface, the melting points of solder balls between the longitudinally adjacent chips are the same.

19. The packaging method according to any one of claims 15 to 18, characterized in that: In the step of realizing welding of adjacent chips by using solder balls formed between adjacent chips, the material of the solder balls includes doping elements, and the concentration of the doping elements is negatively correlated with the melting point of the solder balls.

20. The packaging method according to claim 19, characterized in that: In the step of realizing the welding of adjacent chips by using solder balls formed between adjacent chips, the doping elements include one or more of lead, bismuth, cadmium and indium.

21. The packaging method according to any one of claims 15 to 18, characterized in that: In the step of realizing welding of adjacent chips by using solder balls formed between adjacent chips, the material of the solder balls includes doping elements, and the concentration of the doping elements is positively correlated with the melting point of the solder balls.

22. The packaging method according to claim 21, characterized in that: In the step of realizing welding of adjacent chips by using solder balls formed between adjacent chips, the doping elements include one or more of nickel, silver, copper, iron, aluminum and vanadium.

23. The packaging method according to claim 15, characterized in that: The solder balls formed between adjacent chips are used to realize the soldering of adjacent chips. After a plurality of the chips are stacked in the longitudinal direction to form a chip structure, the packaging method further comprises: performing a reflow soldering process on the chip structure.

24. The packaging method according to claim 23, characterized in that: The chip structure is heated by the preset heating surface to perform a reflow soldering process on the chip structure.

25. The packaging method according to claim 15, characterized in that: The solder balls formed between adjacent chips are used to weld adjacent chips. In the step of stacking a plurality of the chips longitudinally to form a chip structure, the plurality of the chips stacked longitudinally are arranged on a substrate to form a high bandwidth memory.

Images