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CN-121988511-A - Technological method for uniform gluing and hot press forming based on silk screen

CN121988511ACN 121988511 ACN121988511 ACN 121988511ACN-121988511-A

Abstract

The invention discloses a process method based on uniform gluing and hot-press forming of a silk screen, which comprises the following steps of preparing a silk screen template, gluing, pre-solidifying and hot-press forming, manufacturing an opening pattern and a hollowed pattern matched with a gluing area of a wafer or a PLP substrate on the silk screen, fixing the opening pattern and the hollowed pattern on a metal frame to obtain the silk screen template, fixing the wafer or the PLP substrate on a vacuum adsorption table, then covering the silk screen template on the surface of the wafer or the PLP substrate in parallel, scraping glue solution along the surface of the silk screen by adopting a polyurethane scraper or a metal scraper, stripping, drying and repeating to obtain the glued wafer or PLP substrate, and placing the glued wafer or PLP substrate in a heating furnace for pre-solidifying treatment and hot-pressing to obtain the wafer or the PLP substrate after hot pressing. The process method adopts a composite process of silk screen gluing and precise hot pressing, and organically combines the patterning capacity of silk screen printing with the leveling, densification and adhesion force enhancing capacity of the hot pressing process, thereby realizing the effect of 1+1> 2.

Inventors

  • JIN YONG
  • PU CHENGHE
  • QUAN RILONG
  • GUO GUIWEI

Assignees

  • 上海凯锐恩半导体科技有限公司

Dates

Publication Date
20260508
Application Date
20260403

Claims (7)

  1. 1. A technological method for uniform gluing and hot press forming based on silk screen is characterized by comprising the following steps: Step 1, preparing a silk screen template, namely manufacturing an opening pattern and a hollowed-out pattern matched with a gluing area of a wafer or a PLP substrate on a silk screen, and fixing the opening pattern and the hollowed-out pattern on a metal frame to obtain the silk screen template; Step 2, gluing, namely fixing a wafer or a PLP substrate on a vacuum adsorption table, covering the surface of the wafer or the PLP substrate with the silk screen template prepared in the step 1 in parallel, scraping the glue solution along the surface of the silk screen by adopting a polyurethane scraper or a metal scraper, vertically upwards stripping the silk screen template, drying, and repeating the scraping-stripping operation to obtain the glued wafer or PLP substrate; Step 3, pre-curing, namely placing the glued wafer or PLP substrate obtained in the step 2 into a heating furnace for pre-curing treatment to obtain a pre-cured wafer or PLP substrate; And 4, hot press molding, namely placing the pre-cured wafer or PLP substrate obtained in the step 3 on a hot press for hot press to obtain the hot pressed wafer or PLP substrate.
  2. 2. The process of claim 1, wherein the wafer in step 1 has a dimension of one of 6 inches, 8 inches, 12 inches; The PLP substrate in step 1 has a size of one of 300mm×300mm, 510mm×515mm, 600mm×600 mm; the opening pattern in the step 1 is a round shape with the diameter being 0.5-2 mm smaller than the diameter of the wafer or a square shape with the side length being 0.5-2 mm smaller than the PLP substrate; The hollowed-out patterns in the step 1 are circular concentric double-ring composite patterns, square concentric double-ring composite patterns and the like, and the meshes are square; In the step 1, the silk screen is a stainless steel wire or polyester wire woven screen, the mesh number is 100-500 meshes, the fine gluing area is 300-500 meshes, the thick gluing area is 200-250 meshes, the thickness is 15-100 mu m, and the opening ratio is 45% -75%.
  3. 3. The process according to claim 1, wherein the accuracy of the edge area of the hollowed-out pattern in step 1 is controlled to be +/-0.01 mm; and (3) tensioning force of the silk screen template in the step (1) is 25-30N/cm.
  4. 4. The process according to claim 1, wherein the levelness error of the vacuum adsorption workbench in the step 2 is less than or equal to 0.005mm/m; in the step 2, the distance between the silk screen template and the surface of the wafer or the PLP substrate is 0.1-0.3 mm; The viscosity of the glue solution in the step 2 is 500-20000 mPas.
  5. 5. The process method according to claim 1, wherein the doctor-strip operation in step 2 is specifically that a glue solution is linearly applied to a starting position of a doctor blade on a screen, the length of the glue solution strip is smaller than the width of a glue coating area, a polyurethane doctor blade or a metal doctor blade is adopted to carry out doctor-strip on the surface of the screen at a constant speed of 5-15 mm/s, the included angle between the doctor blade and the screen is 35-90 degrees, the doctor-strip pressure is 0.005-0.02 MPa, a screen template is vertically and upwards stripped at a speed of 5-10 mm/s after the doctor-strip is carried out, the drying is carried out at 20-30 ℃ for 3-5 min, and the operation is repeated for 2-3 times, so that a glued wafer or PLP substrate is obtained; the length of the glue solution strip is 3-5 mm smaller than the size of the wafer or the PLP substrate, and the width of the glue coating area is 0.5-2 mm smaller than the size of the wafer or the PLP substrate; The line width of the silk screen is 20-60 mu m; The thickness of the glue layer of the glued wafer or PLP substrate is 50-200 mu m.
  6. 6. The process method according to claim 1, wherein the pre-curing treatment in the step 3 is specifically that hot air circulation heating is adopted, the glued wafer or PLP substrate is placed in a heating furnace with the temperature of 80-100 ℃ for heat preservation for 5-8 min, and the humidity of a cavity in the pre-curing process is 30-50%.
  7. 7. The process method according to claim 1, wherein in the step 4, the pre-cured wafer or PLP substrate is placed on a hot pressing die of a hot press, the temperature is raised to 120-160 ℃ at a temperature rise rate of 5-10 ℃ per minute, the wafer or PLP substrate is pressed for 1-2 min by the die under the constant speed of 0.5-2 MPa, and vacuum is synchronously pumped in the hot pressing process, so that the vacuum degree of a cavity is minus 100Pa to minus 50Pa.

Description

Technological method for uniform gluing and hot press forming based on silk screen Technical Field The invention belongs to the technical field of semiconductor manufacturing, and particularly relates to a technological method based on uniform gluing and hot press molding of a silk screen. Background In the field of semiconductor manufacturing, with the continuous improvement of chip integration and the miniaturization and high-density development of packaging forms, wafer and PLP substrate back grinding has become one of the core processes. The thickness of the wafer and the PLP substrate can be thinned from 600-700 mu m to 50-200 mu m through a back grinding process, so that the thickness requirements of advanced packaging forms such as stacked packaging, three-dimensional packaging and the like can be met, the thermal resistance of the chip can be reduced, and the electrical performance can be improved. However, in the back grinding process, the high-speed rotating grinding wheel applies continuous mechanical stress to the back surfaces of the wafer and the PLP substrate, which is easy to cause damages such as edge breakage, warpage and cracks of the wafer and the PLP substrate, and meanwhile, particle impurities such as silicon powder generated by grinding may adhere to the surfaces of the wafer and the PLP substrate or invade into gaps, so that the stability and the product yield of the subsequent packaging process are affected. In order to solve the above problems, a layer of back grinding protective adhesive is coated on the front (device) surfaces of the wafer, the PLP substrate, etc. before back grinding to form a complete protective adhesive film. The protective adhesive film needs to have enough mechanical strength, good adhesive force and abrasive resistance to provide reliable mechanical support and surface protection for the substrate in the back grinding process, avoid damage and impurity pollution, and simultaneously, the protective adhesive film needs to be stripped conveniently and thoroughly after the back grinding is finished, and has no residual adhesive residue and no influence on the performance of a front device. Therefore, the coating process of the back grinding protective adhesive directly determines the thickness uniformity, the surface flatness, the adhesive force and the pattern suitability of the protective adhesive film, and is a key link for guaranteeing the back grinding yield of the wafer and the PLP substrate. At present, the coating method of the back grinding protective glue mainly comprises a spin coating method, a doctor blade/slit coating method and a direct hot press forming method, and each glue coating method has obvious limitations. The spin coating method has low material utilization rate, film thickness uniformity error of over +/-10% and strict requirement on the viscosity range of glue solution, the doctor blade/slit coating method has poor adaptability to the surface of the uneven wafer with the height difference on the surface and the PLP substrate, which are attached with chips, and is easy to scratch or uneven in coating, and the direct hot press forming method is usually used as an independent step for flattening the precoated glue layer, but if combined with uneven initial glue coating, the defects of partial glue shortage or glue overflow, void, uneven thickness and the like are caused. In addition, an ultrasonic spraying technology can be used for coating glue solution, the glue solution is atomized into nano-scale particles through high-frequency vibration to realize uniform spraying, and the film thickness error can be controlled within +/-5%, but the technology has the limitations of high equipment cost, narrow viscosity adaptation range of the glue solution (only suitable for low-viscosity glue solution), incapability of directly realizing integrated molding after glue coating and the like. The existing back grinding protective adhesive coating process has obvious short plates in the aspects of thick film uniformity, material utilization rate, non-flat surface adaptability, edge control precision and the like, can not fully adapt to the requirements of complex back grinding scenes such as bump wafers, large-size wafers, substrates, fine protection and the like in the advanced packaging field, and restricts the improvement of the back grinding yield and the reduction of the packaging cost. Therefore, developing a back grinding protective adhesive coating process which has high material utilization rate, uniform thick film forming, accurate patterning, high efficiency and can be widely adapted to various wafers and PLP substrates becomes a technical problem to be solved in the field. Disclosure of Invention In view of the above, the invention provides a technological method for uniform gluing and hot press molding based on silk screens. The method combines the advantages of high material utilization rate and high viscosity adaptability of screen pri