Self-adaptive adhesion structure for rough surface wafer pickup and manufacturing method

Abstract

The invention discloses a self-adaptive adhesion structure for rough surface wafer pickup and a manufacturing method, the self-adaptive adhesion structure comprises a two-layer structure, the surface layer is a bionic dry adhesion layer, the bottom layer is a self-adaptive structure layer, and the surface of the bionic dry adhesion layer is provided with mushroom-shaped tail end structures distributed in an array mode. The self-adaptive structure layer is composed of a structure substrate and a plurality of discrete porous structure units, separated cutting grooves are formed between the adjacent discrete porous structure units, and separation grooves corresponding to the cutting grooves are formed in the bionic dry adhesion layer. The manufacturing method comprises the following steps: firstly preparing the pre-cured unfoamed backing by utilizing a molding process, then preparing and treating the bionic dry adhesion template by utilizing photoetching, reverse molding and hot pressing methods, then assembling the bionic dry adhesion layer and the pre-cured unfoamed backing, and finally finishing the preparation of the self-adaptive adhesion structure by utilizing high-temperature foaming and laser cutting processes. According to the invention, conformal contact and high-performance adhesion of the wafer with the rough surface are realized, and the adhesion pickup reliability of the wafer with the rough surface is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of micro-nano engineering bionic manufacturing, and in particular relates to an adaptive adhesion structure for picking up wafers with rough surfaces and a manufacturing method. Background Art

[0002] Reliable picking and handling of rough surface wafers is a key link in the midstream stage of the semiconductor chip industry chain - wafer manufacturing and processing, and is directly related to the quality of integrated circuit (IC) devices in the downstream stage of the industry chain. For example, bare wafers (Ra: 0.78~5.48 mm) cut from silicon ingots need to be reliably transported to grinding equipment for polishing and grinding to remove defects on the wafer surface to improve the performance and reliability of the final finished chip; for another example, wafers after etching mask patterns (chip grain isolation area width: 30~150 μm) need to be reliably transported to ion implantation, dicing and other equipment for ion implantation, thin film deposition and dicing and cutting processes necessary for chip production. However, the surface of bare wafers and wafers after etching patterns is uneven, and the surface roughness seriously limits the reliable picking and application of conventional smooth surface wafer picking technologies represented by vacuum negative pressure adsorption, electrostatic adsorption, Bernoulli chuck adsorption, etc. on rough surface wafers. Although the current mechanical clamping and picking method can meet the rough surface wafer picking needs of the industry chain to a certain extent, the development trend of "large size and thin thickness" of wafers (transition from 12 inches to 18 inches, thickness less than 500 μm) makes the new generation of wafers more fragile, and the mechanical clamping and picking technology with high interface picking stress faces severe challenges. How to achieve reliable picking and handling of fragile and rough surface wafers is a technical constraint to improve the leapfrog development of the semiconductor chip industry chain yield. Summary of the invention

[0003] In order to solve the above-mentioned technical problems of the prior art, the purpose of the present invention is to provide an adaptive adhesion structure and a manufacturing method for picking up rough surface wafers. The adaptive adhesion structure has adaptive conformal contact and high-performance adhesion functions, and can be used for the reliable picking and handling of large-size, thin-thickness, fragile and rough-surface wafers.

[0004] In order to achieve the above object, the technical solution adopted by the present invention is: An adaptive adhesion structure for picking up wafers with rough surfaces comprises a two-layer structure, wherein the surface layer is a bionic dry adhesion layer and the bottom layer is an adaptive structure layer; the surface of the bionic dry adhesion layer has an array of mushroom-shaped terminal structures, and the adaptive structure layer is composed of a structural substrate and a plurality of discrete porous structure units; separated cutting grooves are arranged between adjacent discrete porous structure units, and separation grooves corresponding to the cutting grooves are opened on the bionic dry adhesion layer.

[0005] A method for manufacturing an adaptive adhesion structure for rough surface wafer picking, comprising the following steps: The first step is to prepare a pre-cured unfoamed backing: a composite material in a fluid state is molded and filled in a machined template, and then a pre-curing treatment is performed, and then a layer of polymer is further filled in the machined template as a structural substrate; the composite material and the structural substrate are further pre-cured, and a pre-cured unfoamed backing is obtained after demoulding; The second step is the preparation and processing of the bionic dry adhesion template: first, a mushroom-shaped terminal structure hole array is made on the photoresist, and the PDMS prepolymer is molded and filled on it. After complete curing, the PDMS imprint template with an array of mushroom-shaped terminal structures is demolded to obtain a PDMS imprint template; then, the PDMS imprint template is hot-pressed onto the thermoplastic and kept for 10 minutes, and then cooled to room temperature and demolded to obtain a bionic dry adhesion template; The third step is the assembly of the bionic dry adhesion layer and the pre-cured unfoamed backing: a layer of polymer is spin-coated on the surface of the bionic dry adhesion template; the pre-cured unfoamed backing is then attached to the spin-coated filled polymer, and heated at 50°C for 4 hours to achieve complete curing and self-connection of the two, and a cured self-connection structure is obtained after demoulding; The fourth step is the preparation of the adaptive adhesive structure: the cured self-connecting structure is foamed at high temperature to expand the composite material into a porous structure backing; then the laser cutting process parameters are set, and the laser is used to perform customized cutting on the surface of the foamed cured self-connecting structure, that is, the porous structure backing is cut into several discrete porous structure units to obtain an adaptive adhesive structure.

[0006] In the first step, the composite material is obtained by mixing the polymer and the foaming agent in a mass ratio of 100:5-10 and fully stirring for 10 hours by a small mechanical stirrer; the foaming agent is selected from sodium bicarbonate or ammonium bicarbonate or azoisobutyronitrile or benzenesulfonylhydrazide.

[0007] In the first step, the first pre-curing process parameter is heating at 50° C. for 5 minutes, and the second pre-curing process parameter is heating at 50° C. for 20 to 30 minutes.

[0008] In the first step, the sum of the thickness of the composite material and the structural substrate is equal to the depth of the machined template.

[0009] In the second step, the thermoplastic plastic is selected from polycarbonate plastic, polystyrene plastic or polypropylene plastic.

[0010] In the second step, the diameter of a single mushroom-shaped terminal structure hole of the bionic dry adhesion template is ten microns.

[0011] In the third step, the thickness of the polymer filled by spin coating is on the scale of several microns.

[0012] The polymers involved in the first step and the third step are made of the same material, namely silicone rubber or polyurethane.

[0013] In the fourth step, the high-temperature foaming process parameters are heating at 60-110° C. for 1-5 minutes; and the thickness of the discrete porous structure unit obtained by laser cutting is in the millimeter scale.

[0014] The beneficial effects of the present invention are: The present invention proposes an adaptive adhesion structure and a manufacturing method for rough surface wafer picking. The adaptive adhesion structure utilizes the contact adaptive characteristics of the underlying adaptive structural layer to achieve conformal contact and high-performance adhesion of the surface bionic dry adhesion layer to the rough surface wafer, thereby improving the reliability of adhesion and picking of rough surface wafers, meeting the needs of reliable picking and handling of large-sized, thin-thickness, fragile and rough surface wafers in the wafer manufacturing and processing links of the semiconductor chip industry chain, and is expected to improve the yield rate of wafer manufacturing and processing, laying a good foundation for the high quality of downstream IC devices in the industry chain; secondly, the low-cost and high-efficiency multi-structure, multi-material coupling manufacturing process can realize the integrated, controllable and reliable manufacturing of the adaptive adhesion structure, and significantly improve its fatigue service life. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a schematic structural diagram of the adaptive adhesion structure of the present invention.

[0016] Figure 2 It is a schematic diagram of the adaptive adhesion structure of the present invention conformally contacting a rough surface wafer.

[0017] Figure 3 It is a schematic diagram of the present invention after molding the filling composite material and the structural substrate in the machined template.

[0018] Figure 4 It is a schematic diagram of the structure of the pre-cured unfoamed backing of the present invention.

[0019] Figure 5 It is a schematic structural diagram of the PDMS imprint template of the present invention.

[0020] Figure 6 Schematic diagram of the hot pressing process of the present invention.

[0021] Figure 7 It is a schematic structural diagram of the bionic dry adhesion template of the present invention.

[0022] Figure 8 It is a schematic diagram of spin coating a filling polymer on the surface of a bionic dry adhesion template according to the present invention.

[0023] Fig. 9 It is a schematic diagram of assembling the uncured bionic dry adhesive layer of the present invention and the precured unfoamed backing.

[0024] Fig.10It is a schematic structural diagram of the cured self-connecting structure obtained after demoulding of the present invention.

[0025] Fig.11 It is a schematic diagram of the high temperature foaming process of the present invention.

[0026] Fig.12 Schematic diagram of preparing adaptive adhesion structure by laser cutting according to the present invention.

[0027] In the figure: 1. Bionic dry adhesion layer; 2. Structural substrate; 3. Discrete porous structural unit; 4. Rough surface wafer; 5. Machined template; 6. Composite material; 7. PDMS imprint template; 8. Thermoplastic plastic; 9. Bionic dry adhesion template; 10. Uncured bionic dry adhesion layer; 11. Porous structure backing; 12. Laser; 13. Cutting groove; 14. Mushroom-shaped end structure. DETAILED DESCRIPTION

[0028] The present invention will be described in detail below with reference to the accompanying drawings and embodiments.

[0029] Reference Figure 1 An adaptive adhesion structure for rough surface wafer picking includes a two-layer structure, a surface layer is a bionic dry adhesion layer 1, and a bottom layer is an adaptive structure layer; the surface of the bionic dry adhesion layer 1 has an array of mushroom-shaped end structures 14, and the adaptive structure layer is composed of a structural substrate 2 and a plurality of discrete porous structure units 3; separated cutting grooves 13 are provided between adjacent discrete porous structure units 3, and separation grooves corresponding to the cutting grooves 13 are opened on the bionic dry adhesion layer 1.

[0030] In the specific implementation process, refer to Figure 2 The bionic dry adhesion layer 1 adopts a mushroom-shaped end structure design, which can effectively weaken the stress singularity of the contact edge, realize the crack nucleation from the inside of the contact end and expand outward during the desorption process, and achieve the adhesion enhancement effect by suppressing the initiation of edge cracks; at the same time, each discrete porous structure unit 3 in the adaptive structure layer is subjected to independent / unaffected forces, and the excellent contact adaptive characteristics of the discrete porous structure unit 3 can achieve full contact between the bionic dry adhesion layer 1 and the local area of ​​the rough surface wafer 4, significantly increase the contact area, and improve the reliability of interface adhesion pickup; secondly, the arrayed distribution of the discrete porous structure unit 3 can effectively eliminate the stress crosstalk between the units during the interface separation process, and avoid the adhesion failure of the overall interface due to local separation of the contact interface.

[0031] A method for manufacturing an adaptive adhesion structure for rough surface wafer picking, comprising the following steps: Step 1: Preparation of pre-cured unfoamed backing: refer to Figure 3, a composite material 6 in a fluid state is molded and filled in a machined template 5 with a depth of millimeters after low surface energy treatment, and heated at 50°C for 5 minutes to achieve pre-curing, and then a layer of polymer is continuously filled in the machined template 5 as a structural substrate 2; the composite material 6 and the structural substrate 2 are heated at 50°C for 20 to 30 minutes for further pre-curing treatment, and a pre-cured unfoamed backing with a certain viscosity is obtained after demoulding, such as Figure 4 As shown; Preferably, the composite material 6 is obtained by mixing a polymer and a foaming agent in a mass ratio of 100:5-10, and fully stirring for 10 hours by a small mechanical stirrer; the foaming agent is selected from a material that is easy to obtain, has a large gas emission, and a starting decomposition temperature greater than 50° C., such as sodium bicarbonate or ammonium bicarbonate or azoisobutyronitrile or benzenesulfonylhydrazide; the sum of the thickness of the composite material 6 and the structural substrate 2 is equal to the depth of the machining template 5; Step 2: Preparation and treatment of the bionic dry adhesion template: The bionic dry adhesion template 9 is prepared by photolithography and hot pressing. First, a mushroom-shaped terminal structure hole array is made on the photoresist, and a layer of PDMS prepolymer (PDMS body and curing agent are mixed in a mass ratio of 10:1) with a thickness of millimeters is molded and filled on it. After heating and curing at 80°C for 2 hours, the PDMS imprint template 7 with an array of mushroom-shaped terminal structures is demolded. Figure 5 shown; reference Figure 6 Then, the PDMS imprint template 7 is hot pressed onto the thermoplastic 8 and kept for 10 minutes, and then demoulded after cooling to room temperature to obtain the biomimetic dry adhesion template 9, as shown in FIG. Figure 7 As shown; Preferably, the thermoplastic plastic 8 is polycarbonate plastic or polystyrene plastic or polypropylene plastic; the diameter of the single mushroom-shaped terminal structure hole of the bionic dry adhesion template 9 is ten microns in size, so as to ensure that the bionic dry adhesion layer 1 after demoulding can fully contact the rough area of ​​the rough surface wafer 4; Step 3: Assembly of biomimetic dry adhesive layer and pre-cured unfoamed backing: refer to Figure 8 , a layer of polymer (i.e., uncured bionic dry adhesion layer 10) is spin-coated on the surface of the bionic dry adhesion template 9; and then a pre-cured unfoamed backing is attached to the spin-coated filled polymer ( Fig. 9 ), and placed in a 50°C environment and heated for 4 hours to achieve complete curing and self-connection of the two, and after demoulding, a cured self-connection structure is obtained, such as Fig.10 As shown; Preferably, the thickness of the spin-coated filled polymer is a few micrometers in size, so as to improve the contact adaptability of the bionic dry adhesion layer 1 to the rough surface wafer 4; Preferably, the polymers involved in the first step and the third step are made of the same material, silicone rubber or polyurethane; Step 4: Preparation of adaptive adhesion structure: refer to Fig.11 , the cured self-connecting structure is placed in a 60-110°C environment and heated for 1-5 minutes for high-temperature foaming. During this process, the foaming agent will decompose into gas, causing the composite material 6 to expand into a porous structure backing 11; refer to Fig.12 , and then set the laser cutting process parameters, use the laser 12 to perform customized cutting on the surface of the solidified self-connecting structure after foaming, and the porous structure backing 11 is cut into a number of discrete porous structure units 3 with a thickness of millimeters, realizing the integrated, controllable and reliable manufacturing of the adaptive adhesion structure.

[0032] The adaptive adhesion structure of the present invention utilizes the contact adaptive characteristics of the underlying adaptive structural layer to achieve conformal contact and high-performance adhesion of the surface bionic dry adhesion layer to the rough surface wafer, thereby improving the reliability of adhesion and picking up of rough surface wafers, and meeting the needs of reliable picking up and handling of large-sized, thin-thickness, fragile and rough-surface wafers in the wafer manufacturing and processing links of the semiconductor chip industry chain. It is expected to improve the yield rate of wafer manufacturing and processing, and lay a good foundation for the high quality of downstream IC devices in the industry chain; secondly, the low-cost and high-efficiency multi-structure and multi-material coupling manufacturing process can realize the integrated, controllable and reliable manufacturing of the adaptive adhesion structure, and significantly improve its fatigue service life.

Claims

1. An adaptive adhesion structure for rough surface wafer picking, characterized in that: The invention comprises a two-layer structure, wherein the surface layer is a bionic dry adhesion layer (1), and the bottom layer is an adaptive structural layer; The surface of the bionic dry adhesion layer (1) has mushroom-shaped terminal structures (14) distributed in an array, and the adaptive structural layer is composed of a structural substrate (2) and a plurality of discrete porous structural units (3); separating cutting grooves (13) are provided between adjacent discrete porous structural units (3), and the bionic dry adhesion layer (1) is provided with separation grooves corresponding to the cutting grooves (13).

2. A method for manufacturing an adaptive adhesion structure for rough surface wafer picking, characterized in that: The following steps are involved: The first step is to prepare a pre-cured unfoamed backing: a composite material (6) in a fluid state is molded and filled in a machined template (5), and then a pre-curing treatment is performed, and then a layer of polymer is further filled in the machined template (5) as a structural substrate (2); the composite material (6) and the structural substrate (2) are further pre-cured, and a pre-cured unfoamed backing is obtained after demoulding; The second step is the preparation and processing of the bionic dry adhesion template: first, a mushroom-shaped terminal structure hole array is made on the photoresist, and the PDMS prepolymer is molded and filled thereon, and after complete curing, the PDMS imprint template (7) with an array of mushroom-shaped terminal structures is demolded; then, the PDMS imprint template (7) is hot-pressed onto the thermoplastic (8) and maintained for 10 minutes, and after cooling to room temperature, the template is demolded to obtain the bionic dry adhesion template (9); The third step is to assemble the biomimetic dry adhesion layer and the pre-cured unfoamed backing: a layer of polymer is spin-coated on the surface of the biomimetic dry adhesion template (9); then the pre-cured unfoamed backing is attached to the spin-coated filled polymer, and heated at 50°C for 4 hours to achieve complete curing and self-connection of the two, and a cured self-connection structure is obtained after demoulding; The fourth step is the preparation of the adaptive adhesive structure: the cured self-connecting structure is subjected to high-temperature foaming to expand the composite material (6) into a porous structure backing (11); then the laser cutting process parameters are set, and the laser (12) is used to perform customized cutting on the surface of the foamed cured self-connecting structure, that is, the porous structure backing (11) is cut into a plurality of discrete porous structure units (3), thereby obtaining an adaptive adhesive structure.

3. The method for manufacturing an adaptive adhesion structure for rough surface wafer picking according to claim 2, characterized in that: In the first step, the composite material (6) is obtained by mixing a polymer and a foaming agent in a mass ratio of 100:5-10 and stirring them for 10 hours by a small mechanical stirrer; the foaming agent is selected from sodium bicarbonate, ammonium bicarbonate, azoisobutyronitrile or benzenesulfonylhydrazide.

4. The method for manufacturing an adaptive adhesion structure for rough surface wafer picking according to claim 2, characterized in that: In the first step, the first pre-curing process parameter is heating at 50° C. for 5 minutes, and the second pre-curing process parameter is heating at 50° C. for 20 to 30 minutes.

5. The method for manufacturing an adaptive adhesion structure for rough surface wafer picking according to claim 2, characterized in that: In the first step, the sum of the thicknesses of the composite material (6) and the structural substrate (2) is equal to the depth of the machining template (5).

6. The method for manufacturing an adaptive adhesion structure for rough surface wafer picking according to claim 2, characterized in that: In the second step, the thermoplastic plastic (8) is selected from polycarbonate plastic, polystyrene plastic or polypropylene plastic.

7. The method for manufacturing an adaptive adhesion structure for rough surface wafer picking according to claim 2, characterized in that: In the second step, the diameter of a single mushroom-shaped terminal structure hole of the bionic dry adhesion template (9) is ten micrometers.

8. The method for manufacturing an adaptive adhesion structure for rough surface wafer picking according to claim 2, characterized in that: In the third step, the thickness of the polymer filled by spin coating is on the scale of several microns.

9. The method for manufacturing an adaptive adhesion structure for rough surface wafer picking according to claim 2, characterized in that: The polymers involved in the first step and the third step are made of the same material, namely silicone rubber or polyurethane.

10. The method for manufacturing an adaptive adhesion structure for rough surface wafer pickup according to claim 2, characterized in that: In the fourth step, the high temperature foaming process parameters are heating at 60-110° C. for 1-5 minutes; the thickness of the discrete porous structure unit (3) obtained by laser cutting is in the millimeter scale.

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