A method of filling a semiconductor device package with polyimide

Abstract

This invention proposes a method for filling semiconductor device housings with polyimide. First, a first layer of polyimide is coated inside the housing of the assembled semiconductor device. The housing is then placed in an oven with a protective gas atmosphere and left to stand at room temperature, allowing the first layer of polyimide to fill the gaps between the devices inside the housing. A second layer of polyimide is then coated inside the housing, and the housing is again placed in an oven with a protective gas atmosphere and left to stand at room temperature, allowing the second layer of polyimide to be evenly distributed inside the housing. The polyimide is then subjected to a temperature-step curing process in the oven under a protective gas atmosphere. This invention fills the gaps between semiconductor devices and the device surface in stages through a two-coating process inside the housing, ensuring uniform coverage and surface flatness of the polyimide within the housing, avoiding bubble formation. The temperature-step curing process after filling ensures the thermal stability of the polyimide.

Description

Technical Field

[0001] This invention relates to a method for filling the casing of a semiconductor device with polyimide, belonging to the field of semiconductor device technology. Background Technology

[0002] Polyimide is an organic polymer material with both imine rings and photosensitive groups on its polymer chain. It has excellent thermal stability and good properties in chemical, electrical, mechanical and photosensitive aspects, and plays an important role in microelectronics, aerospace, liquid crystal display, optoelectronics and other fields.

[0003] Typically, in the semiconductor manufacturing process of wafer-level products, the step height differences of devices are generally on the nanometer to micrometer scale. When filling their surfaces with polyimide, planarization can be achieved by adjusting the polyimide coating rate. However, the packaged devices differ from wafer-level products. They contain a large number of semiconductor devices, bonding wires, etc., and the step height differences of semiconductor devices can even reach the millimeter scale. This makes it difficult to achieve complete coverage of the package interior using existing technologies, especially the gaps between devices. Furthermore, when using existing processes to fill the package with polyimide, the filling capacity on the device surface and in the gaps between devices is limited. Polyimide cannot be uniformly covered, and air bubbles are easily generated during the filling process. During high-temperature curing, a porous cured layer is easily formed, which fails to achieve the purpose of using polyimide. Summary of the Invention

[0004] The purpose of this invention is to solve the above-mentioned problems existing in the current semiconductor manufacturing process and to propose a method for filling the semiconductor device casing with polyimide.

[0005] The technical solution of the present invention: a method for filling the package of a semiconductor device with polyimide, specifically including the following steps:

[0006] 1) Assemble semiconductor devices into an uncapped housing through arrangement, sintering, and bonding processes;

[0007] 2) Coating the first layer of polyimide inside the tube: The first layer of polyimide is coated inside the tube using a suspension coating process. The suspension coating thickness and rate are matched with the tube wall height and the step distribution of the devices inside the tube. The suspension coating rate is 1500 rad / min ~ 4000 rad / min. When coating the first layer of polyimide, the polyimide only fills the gaps between the devices inside the tube. There are no air bubbles in the filled area. After suspension coating, there is no polyimide on the surface of the device. The upper surface of the polyimide is on the same plane as the upper surface of the adjacent device.

[0008] 3) Place the tube shell in an oven with a protective gas atmosphere and let it stand at room temperature. The protective gas is nitrogen. Under stable nitrogen pressure in the oven, the oxygen content is less than 100 ppm. The standing time of the tube shell in the oven depends on the viscosity of the polyimide material. The reference standing time is 0.5 hours to 16 hours.

[0009] 4) Coating the second layer of polyimide inside the casing: The second layer of polyimide is coated inside the casing using a suspension coating process. The suspension coating thickness and rate are matched with the height of the casing wall and the step distribution of the devices inside the casing. The suspension coating rate is 100 rad / min ~ 2000 rad / min, which is less than the suspension coating rate of the first layer of polyimide. When coating the second layer of polyimide, the polyimide is distributed flatly inside the casing. The surface height in the flat distribution state is higher than the highest point of the devices, bonding wires, etc. inside the casing, and there are no air bubbles in the filling area.

[0010] 5) Place the tube shell in an oven with a protective gas atmosphere and let it stand at room temperature, under the same conditions as step 3).

[0011] 6) In a protective gas atmosphere, polyimide is cured in an oven using a temperature-step curing process. This temperature-step curing process includes four steps: pre-curing, solvent removal curing, polyimide curing, and cooling.

[0012] ① When raising the oven temperature from room temperature to the pre-curing temperature, the temperature should be increased slowly and linearly, and the heating time should not be less than 1 hour to prevent bubbles from forming due to excessive heating. The pre-curing temperature and time are related to the thickness and area of ​​the polyimide and the flatness of the device steps. The pre-curing temperature range is 50℃~100℃, and the pre-curing time is 0.5 hours~16 hours.

[0013] ② The oven temperature should be raised from the pre-curing temperature to the desolventizing curing temperature slowly and linearly, with a heating time of at least 2 hours to prevent rapid heating and the formation of bubbles. The desolventizing curing temperature must be higher than the pre-curing temperature. The desolventizing curing temperature and time are related to the thickness and area of ​​the polyimide and the flatness of the device steps. The desolventizing curing temperature range is 100℃~180℃, and the desolventizing curing time is 0.5 hours~12 hours.

[0014] ③ The oven temperature should be raised from the solvent removal curing temperature to the polyimide curing temperature. The temperature increase should be slow and linear, and the heating time should be no less than 2 hours to prevent rapid heating and the formation of bubbles. The polyimide curing temperature must be higher than the solvent removal curing temperature. The polyimide curing temperature and time are related to the polyimide thickness, area, and the flatness of the device steps. The polyimide curing temperature range is 250℃~350℃, and the polyimide curing time is 0.5 hours~6 hours.

[0015] ④ The oven temperature should be reduced from the polyimide curing temperature to room temperature. The temperature should decrease slowly and linearly, and the cooling time should be no less than 3 hours.

[0016] Compared with the prior art, the advantages of the present invention are: the gaps between semiconductor devices and the device surface are filled in the tube by two coating processes in stages, which ensures the uniformity of polyimide coverage and surface flatness in the tube and avoids the generation of bubbles. The polyimide after filling is subjected to a step-by-step curing process to ensure the thermal stability of polyimide. Attached Figure Description

[0017] Appendix Figure 1 ~Appendix Figure 3 This is a schematic flowchart of a method for filling a semiconductor device casing with polyimide in an embodiment of the present invention.

[0018] In the figure, 101 is the tube shell, 102 is the device, 103 is the bonding wire, 2 is the first polyimide layer, and 3 is the second polyimide layer. Detailed Implementation

[0019] The technical solution of the present invention will be further described below with reference to the accompanying drawings. Examples of the embodiments are shown in the drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0020] To simplify the disclosure of this invention, specific examples of components and arrangements are described below. These are merely examples and are not intended to limit the invention. Furthermore, reference numerals and / or letters may be repeated in different examples; such repetition is for simplification and clarity and does not in itself indicate a relationship between the various embodiments and / or arrangements discussed. In addition, examples of various specific processes and materials are provided in this invention, but those skilled in the art will recognize the application of other processes and / or the use of other materials.

[0021] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., indicate that a specific feature, structural material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structural materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0022] like Figures 1-3 The method for filling a semiconductor device package with polyimide, as shown, includes the following specific steps:

[0023] 1) The semiconductor devices 102 inside the housing 101 have been assembled, including device arrangement, sintering, bonding 103, etc., and the housing 101 has not been sealed.

[0024] 2) The first polyimide layer 2 is coated inside the tube shell 101 using a suspension coating process at a rate of 2500 rad / min;

[0025] 3) Place the tube shell 101 in an oven with a nitrogen protective atmosphere and let it stand at room temperature for 16 hours. The oxygen content is less than 100 ppm, so that the first polyimide layer 2 fills the gap between each device 102 inside the tube shell 101. There are no air bubbles in the filling area, and there is no polyimide on the surface of each device 102. The upper surface of the polyimide layer is on the same plane as the upper surface of each device 102.

[0026] 4) The second polyimide layer 3 is coated inside the tube using a suspension coating process at a rate of 300 rad / min;

[0027] 5) Place the tube shell 101 in an oven with a nitrogen protective atmosphere and let it stand at room temperature for 16 hours. The oxygen content is less than 100 ppm, so that the second polyimide layer 3 is distributed flatly inside the tube shell 101. The surface of the polyimide is higher than the highest point of each device 102 and bonding wire 103 inside the tube shell 101, and there are no air bubbles in the filling area.

[0028] 6) Under a nitrogen protective atmosphere, the first polyimide layer 2 and the second polyimide layer 3 are cured in an oven. The oven temperature is slowly and linearly increased from room temperature to 60°C over 1.5 hours, and then maintained at this temperature for 12 hours; the oven temperature is then slowly increased from 60°C to 140°C over 2.5 hours, and then maintained at this temperature for 6 hours; the oven temperature is then slowly increased from 140°C to 280°C over 3 hours, and then maintained at this temperature for 6 hours; finally, the oven temperature is slowly decreased from 280°C to room temperature over 4 hours. After cooling, the tube shell is removed. During the heating process, the heating rate is constantly monitored to prevent excessively rapid heating and the generation of bubbles.

[0029] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A method of filling a semiconductor device package with polyimide, characterized by, The method specifically includes the following steps: 1) Assemble semiconductor devices into an uncapped housing through arrangement, sintering, and bonding processes; 2) Coat the inside of the tube with a first layer of polyimide; 3) Place the tube shell in an oven with a protective gas atmosphere and let it stand at room temperature; 4) Coat the inside of the tube with a second layer of polyimide; 5) Place the tube shell in an oven with a protective gas atmosphere and let it stand at room temperature; 6) Polyimide is cured in a temperature-step manner in an oven under a protective gas atmosphere. The temperature-step curing process in step 6) includes four processes: pre-curing, solvent removal curing, polyimide curing, and cooling. ① Pre-curing: The oven temperature is raised from room temperature to the pre-curing temperature, and the temperature rises slowly and linearly. The heating time is not less than 1 hour. The pre-curing temperature range is 50℃~100℃, and the pre-curing maintenance time is 0.5 hours~16 hours. ② Solvent removal curing: The oven temperature is raised from the pre-curing temperature to the solvent removal curing temperature. The temperature rises slowly and linearly, and the heating time should not be less than 2 hours. The solvent removal curing temperature range is 100℃~180℃, and the solvent removal curing time is 0.5 hours~12 hours. ③ Polyimide curing: The oven temperature is raised from the solvent-free curing temperature to the polyimide curing temperature. The temperature increases slowly and linearly, and the heating time is not less than 2 hours. The polyimide curing temperature range is 250℃~350℃, and the polyimide curing time is 0.5 hours~6 hours. ④ Cooling: The oven temperature is reduced from the polyimide curing temperature to room temperature. The temperature decreases slowly and linearly, and the cooling time is not less than 3 hours.

2. A method of filling a semiconductor device package with polyimide according to claim 1, wherein: In step 2), the first layer of polyimide is coated inside the tube using a suspension coating process. The suspension coating thickness and rate are matched with the tube wall height and the step distribution of the device inside the tube. The suspension coating rate is 1500 rad / min ~ 4000 rad / min.

3. The method of filling a semiconductor device package with polyimide of claim 1 wherein: In step 2), when the first layer of polyimide is coated inside the tube, the polyimide only fills the gaps between the devices inside the tube, and there are no air bubbles in the filled area. After the coating is applied, there is no polyimide on the surface of the device, and the upper surface of the polyimide is on the same plane as the upper surface of the adjacent device.

4. The method of filling a semiconductor device package with polyimide of claim 1 wherein: In step 4), the second layer of polyimide is coated inside the tube using a suspension coating process. The suspension coating thickness and rate are matched with the tube wall height and the step distribution of the device inside the tube. The suspension coating rate is 100 rad / min ~ 2000 rad / min, which is less than the suspension coating rate of the first layer of polyimide.

5. The method of filling a semiconductor device package with polyimide of claim 1 wherein: In step 4), when coating the second layer of polyimide inside the tube shell, the polyimide is distributed flatly inside the tube shell. The surface height of the flat distribution state is higher than the highest point of the device and bonding wire inside the tube shell, and there are no air bubbles in the filling area.

6. The method of filling a semiconductor device package with polyimide of claim 1 wherein: In steps 3) and 5), the protective gas atmosphere in the oven is nitrogen, and the oxygen content is less than 100 ppm when the nitrogen pressure in the oven is stable.

7. The method of filling a semiconductor device package with polyimide of claim 1 wherein: In steps 3) and 5), the tube shell is left to stand in the oven for 0.5 hours to 16 hours.

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