A method for metallizing glass vias

Abstract

The present invention discloses a method for metallizing glass vias, belonging to the technical field of printed circuits. The method includes the following manufacturing processes: pre-curing a polymer film; laminating the polymer film onto the upper and lower surfaces of a glass substrate; performing polymer patterning by plasma etching; electroless plating a seed layer on the glass vias; laminating photoresist onto the upper and lower surfaces of the glass substrate after the seed layer is made; performing patterning treatment on the photoresist on the upper and lower surfaces of the glass substrate after the seed layer is made; electroplating copper in the area of the seed layer not covered by the photoresist; stripping the photoresist and etching the seed layer covering the surface of the polymer film layer. This method solves the problem of mechanical damage to the glass caused by laser ablation during the metallization process of glass vias. The polymer film provides a stress buffer layer for the metallization of glass vias and is applicable to glass vias with a higher aspect ratio. This method has simple process steps and has practical value.

Description

Technical Field

[0001] The present invention relates to the technology of via metallization for packaging, and specifically discloses a method for via metallization on a glass substrate, belonging to the technical field of printed circuits. Background Art

[0002] In recent years, glass has become the preferred material for the new generation of interconnect materials. As an insulating material, glass has become an attractive support material for advanced manufacturing and packaging due to its adjustable coefficient of thermal expansion (CTE), excellent surface flatness, high resistivity, and low cost. Its characteristics are specifically outlined as follows: First, glass has a low dielectric constant, low radio frequency loss, and high linearity; Second, compared with other materials, glass has optical transparency, is easy to control in quality, and its high temperature resistance and chemical resistance provide good reliability for the packaging of microelectromechanical systems (MEMS). The preparation of ultra-thin glass can be combined with microelectromechanical systems to achieve ultra-small design; Finally, through glass vias (TGV) are easy to prepare in various ways. Based on the above advantages, three-dimensional interconnection with TGV technology has wide applicability in radio frequency devices, optoelectronic systems, and multi-layer glass substrates.

[0003] To achieve via metallization on a glass substrate, it is necessary to solve the problem of residual stress caused by the mismatch of the coefficient of thermal expansion. Currently, the methods for glass via metallization include sputtering and electroless plating with the introduction of a polymer thin film layer. Among them, the aspect ratio of the vias that can be processed by the sputtering process is limited. In the process method of electroless plating with a polymer thin film layer, there are two methods: laminating the film first and then making glass vias, and making glass vias first, then laminating the film, and then patterning the film. In the process method of electroless plating with a polymer thin film layer where glass vias are made first, on the one hand, the uncured polymer thin film easily flows into the vias, which will increase the thickness of the polymer in the vias, is not conducive to subsequent etching patterning, and is not conducive to the metallization of glass vias with a high aspect ratio, thus affecting the implementation of the subsequent electroless plating process; on the other hand, lasers such as CO2 lasers or UV lasers are usually used to pattern the laminated polymer thin film, but laser ablation faces the problem of possible unnecessary mechanical damage to the glass, affecting the material properties of the glass. Summary of the Invention

[0004] The object of the present invention is to address the deficiencies of the above-mentioned background art and provide an improved electroless plating process method for a polymer thin film layer with glass vias fabricated first, to achieve the object of metallizing the glass vias and solve the technical problems of low yield rate in the current electroless plating process for the polymer thin film layer with glass vias fabricated first and the impact on the properties of glass materials.

[0005] The present invention adopts the following technical solutions to achieve the above object:

[0006] A method for metallizing glass vias, comprising the following steps:

[0007] Step 1, perform pre-curing treatment on the polymer thin film;

[0008] Step 2, laminate the pre-cured polymer thin film layer onto the upper and lower surfaces of a glass substrate prefabricated with glass vias;

[0009] Step 3, perform patterning on the polymer thin film by plasma etching to expose the glass vias;

[0010] Step 4, perform electroless plating on the glass substrate with the glass vias exposed to fabricate a seed layer covering the glass vias and the surface of the polymer thin film;

[0011] Step 5, laminate photoresist onto the upper and lower surfaces of the glass substrate after fabricating the seed layer;

[0012] Step 6, perform patterning on the photoresist on the upper and lower surfaces of the glass substrate to expose the glass vias;

[0013] Step 7, electroplate copper in the seed layer area not covered by the photoresist;

[0014] Step 8, strip the photoresist and etch the seed layer covering the surface of the polymer thin film layer.

[0015] As a further optimized solution of the method for metallizing glass vias, the polymer thin film in Step 1 is an epoxy-based polymer dry film.

[0016] As a further optimized solution of the method for metallizing glass vias, the process for performing pre-curing treatment on the polymer thin film in Step 1 is: the polymer thin film is first stored at room temperature for 12 hours, and then heated in an oven at 100 °C for 20 minutes.

[0017] As a further optimized solution for a method of metallizing vias in glass, the plasma etching method in step three is specifically as follows: First, laminate a dry film photoresist on the upper and lower surfaces of the glass substrate obtained in step two, and pattern the photoresist through a photolithography step to expose the polymer film covering the vias in the glass; at 100 °C, use an RF plasma machine to etch the polymer film covering the vias in the glass in a mixed gas of O2 and CF4. The mixing ratio of O2 and CF4 is preferably 1:4, the power of the RF plasma machine is preferably 400 w, and the etching time of the RF plasma machine is preferably 15 minutes.

[0018] The present invention adopts the above technical solutions and has the following beneficial effects:

[0019] (1) For the method of metallizing vias in glass proposed by the present invention, by laminating a pre-cured polymer film layer on the surface of the glass substrate, it is possible to prevent the uncured polymer film layer from flowing into the vias in the glass, and through plasma etching, the pre-cured polymer film layer is patterned, which has the technical advantages of simple process and being applicable to metallizing vias in glass with a high aspect ratio.

[0020] (2) Compared with the current chemical plating process for making a polymer film layer for vias in glass, the method of metallizing vias in glass proposed by the present invention abandons the operation of laser ablation patterning of the polymer film, and realizes metallization of vias in glass without changing the material properties of the glass substrate, and the fabricated metallized vias in glass have good thermo-mechanical reliability.

[0021] (3) Compared with the process of metallizing vias in glass by physical vapor deposition, in the method of metallizing vias in glass proposed by the present invention, the polymer film is used as a stress buffer layer between the glass and the copper, which can relieve the residual stress caused by the copper to the glass and improve the reliability of metallizing vias in glass. Description of the Drawings

[0022] Figure 1 It is a structural diagram of the glass substrate after laminating the polymer film in the method of metallizing vias in glass proposed by the present invention.

[0023] Figure 2 It is a structural diagram of the glass substrate after plasma etching the polymer film in the method of metallizing vias in glass proposed by the present invention.

[0024] Figure 3 It is a structural diagram of the glass substrate after making the seed layer in the method of metallizing vias in glass proposed by the present invention.

[0025] Figure 4 It is a structural diagram of the glass substrate after laminating the photoresist in the method of metallizing vias in glass proposed by the present invention.

[0026] Figure 5This is the structural diagram of the glass substrate after lithography resist patterning in the glass via metallization method proposed by the present invention.

[0027] Figure 6 This is the structural diagram of the glass substrate after electroplating copper in the glass via metallization method proposed by the present invention.

[0028] Figure 7 This is the structural diagram of the glass substrate after stripping the lithography resist in the glass via metallization method proposed by the present invention.

[0029] Figure 8 This is the flow chart of the glass via metallization method proposed by the present invention.

[0030] Explanation of the reference numerals in the figure: 1. Glass substrate; 2. Glass via; 3. Polymer film; 4. Seed layer; 5. Lithography resist; 6. Copper. Detailed implementation manners

[0031] The technical solutions of the invention will be described in detail below with reference to the accompanying drawings.

[0032] Aiming at the defects of the current electroless plating process for the polymer film layer of glass vias, the present invention proposes an improved electroless plating process for the polymer film layer. In this process, the pre-cured polymer film layer is first laminated on the glass substrate with existing glass vias, then the polymer film patterning is realized through the plasma etching process, and finally the glass via metallization is realized through the semi-additive method, effectively solving the problems of low yield rate of the current electroless plating process for the polymer film layer of glass vias and affecting the material properties of the glass substrate.

[0033] As Figure 8 shown, a method for glass via metallization includes the following eight steps.

[0034] Step 1, perform pre-curing treatment on the polymer film

[0035] In this embodiment, a dry film polymer with a thickness of 5 μm is used. This polymer film is first stored at room temperature for 12 hours, and then heated in an oven at 100 °C for 20 minutes to complete the pre-curing treatment.

[0036] Step 2, laminate the pre-cured polymer film layer on the upper and lower surfaces of the glass substrate prefabricated with glass vias

[0037] As Figure 1 shown, laminate the pre-cured polymer film layer 3 on the upper and lower surfaces of the glass substrate 1 prefabricated with glass vias 2. In this embodiment, a vacuum laminator is used to laminate the polymer film on the glass substrate surface.

[0038] Step 3, perform polymer film patterning by plasma etching method

[0039] As Figure 2 shown, the polymer films laminated on the upper and lower surfaces of the glass substrate are patterned by plasma etching to expose the glass vias 2. In this embodiment, a dry film photoresist is laminated on the upper and lower surfaces of the glass substrate obtained in Step 2, and the photoresist is patterned by photolithography to expose the polymer films covering the glass vias. The exposed polymer films are etched in an RF plasma machine with a gas mixture of O2 and CF4 at 100 °C for 15 minutes. The mixing ratio of O2 and CF4 is 1:4, and the power of the RF plasma machine is 400 w.

[0040] Step Four, fabricate a seed layer covering the glass vias and the surfaces of the polymer films

[0041] As Figure 3 shown, electroless plating is performed on the glass substrate 1 with the glass vias 2 exposed to fabricate a seed layer 4 covering the surfaces of the glass vias 2 and the polymer films 3. In this embodiment, a copper seed layer is fabricated by electroless plating on the vias.

[0042] Step Five, laminate photoresist on the upper and lower surfaces of the glass substrate after fabricating the seed layer

[0043] As Figure 4 shown, photoresist 5 is laminated on the upper and lower surfaces of the glass substrate 1 after fabricating the seed layer 4.

[0044] Step Six, pattern the photoresist on the upper and lower surfaces of the glass substrate

[0045] As Figure 5 shown, the photoresist 5 on the upper and lower surfaces of the glass substrate 1 is patterned to expose the glass vias 2.

[0046] Step Seven, electroplate copper in the areas of the seed layer not covered by the photoresist

[0047] As Figure 6 shown, copper 6 is electroplated in the areas of the seed layer not covered by the photoresist 5.

[0048] Step Eight, strip the photoresist and etch the seed layer

[0049] As Figure 7 shown, the photoresist is stripped, and the seed layer covering the surface of the polymer film layer 3 is etched to achieve metallization of the glass vias with a high aspect ratio.

[0050] The basic principles, main features and advantages of the present invention have been shown and described above. Those skilled in the art should understand that the present invention is not limited by the above specific embodiments. The above specific embodiments and the descriptions in the specification are only for further illustrating the principles and preparation effects of the present invention. Without departing from the spirit and scope of the present invention, the present invention will have various changes and improvements, and these changes and improvements all fall within the scope claimed by the present invention. The scope claimed by the present invention is defined by the claims and their equivalents.

Claims

1. A method for through-glass via metallization, characterized in that: The following steps are involved: Step 1, pre-curing the polymer film; Step 2, laminating the pre-cured polymer film onto the upper and lower surfaces of a glass substrate prefabricated with a through-glass hole; Step 3, patterning the polymer film laminated in step 2 by plasma etching to expose the through-glass holes; Step 4, performing chemical plating on the glass substrate with the through-glass holes exposed after the patterning treatment in step 3, to prepare a seed layer covering the through-glass holes and the surface of the polymer film; Step 5, laminating photoresist on the upper and lower surfaces of the glass substrate after the seed layer is prepared in step 4; Step 6, patterning the photoresist on the upper and lower surfaces of the glass substrate to expose the glass through-holes; Step 7, electroplating copper in the seed layer area not covered by the photoresist on the glass substrate patterned in step 6; Step eight, stripping the photoresist from the glass substrate after copper electroplating in step seven, and etching the seed layer covering the surface of the polymer film.

2. A method for through-glass via metallization according to claim 1, characterized in that: The polymer film in step 1 is an epoxy-based polymer dry film.

3. A method for through-glass via metallization according to claim 1, characterized in that: The specific method of pre-curing the polymer film in step 1 is: firstly store the polymer film at room temperature for 12 hours, and then heat the polymer film in an oven at 100° C. for 20 minutes.

4. A method for through-glass via metallization according to claim 1, characterized in that: The plasma etching method in step three is specifically as follows: firstly, a dry film photoresist is laminated onto the upper and lower surfaces of the glass substrate obtained in step two, and the photoresist is patterned through a photolithography step to expose the polymer film covering the through-glass hole, and the polymer film covering the through-glass hole is etched through an RF plasma machine.

5. A method for through-glass via metallization according to claim 4, characterized in that: The RF plasma machine etches the polymer film covering the through-glass hole in a mixed gas of O 2 and CF 4 at 100° C.

6. A method for through-glass via metallization according to claim 5, characterized in that: The mixing ratio of O2 and CF4 is 1:4, the power of the RF plasma machine is 400w, and the time for the RF plasma machine to etch the polymer film covering the glass through hole is 15 minutes.

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