A thin-film and thick-film hybrid integrated ceramic substrate and preparation method thereof

Abstract

The present invention discloses a thin film / thick film hybrid integrated ceramic substrate, which specifically includes a thin film ceramic substrate prepared by a semiconductor thin film process and a thick film ceramic substrate prepared by a graphic electroplating process. The two share the same ceramic substrate and are electrically connected through a surface metal layer. The thin film ceramic substrate contains thin film multilayer wiring, metal through holes and a gold-tin alloy layer, which is used as a digital / control circuit such as a resistor, inductor, capacitor, etc.; the thick film ceramic substrate contains a thick metal layer and metal through holes, which is used for power device packaging. The patent of the present invention also discloses a method for preparing a thin film / thick film hybrid integrated ceramic substrate. Through the present invention, thin film and graphic electroplating processes are implemented on the same ceramic substrate to achieve hybrid integration of thin film / thick film ceramic substrates and improve device integration and reliability.

Description

Technical Field

[0001] The present invention belongs to the field of electronic packaging technology, and more specifically, relates to a ceramic substrate and a preparation method thereof. Background Art

[0002] Ceramic materials have the advantages of high thermal conductivity, good heat resistance, high insulation, high strength, small thermal expansion coefficient, corrosion resistance, and radiation resistance. They are very suitable for making packaging heat dissipation substrates and have been widely used in electronic component packaging. Ceramic substrates (ceramic circuit boards) are composed of ceramic substrates and metal circuit layers (distributed on the surface and in the through holes). According to the thickness of the circuit layer, they can be divided into thin-film ceramic substrates and thick-film ceramic substrates. Among them, thin-film ceramic substrates are prepared using semiconductor thin film technology and have the advantages of high wiring density (small line width / line spacing), high graphic accuracy, and high integration. However, due to the small thickness of the circuit layer, they are only suitable for small current occasions (such as passive devices). On the contrary, thick-film ceramic substrates can be used in large current and high power load occasions due to the large thickness of the circuit layer, but existing thick-film ceramic substrates (such as thick-film printed ceramic substrates, direct bonding ceramic substrates, etc.) have problems such as low graphic accuracy and high temperature process.

[0003] With the continuous development of semiconductor technology, electronic components are gradually developing in the direction of high power, miniaturization, integration, and multi-function, and higher requirements are also put forward for the performance of ceramic substrates for packaging, including thin film and thick film hybrid integration, high graphic accuracy and miniaturization. However, due to the limitations of traditional ceramic substrate manufacturing processes, ceramic substrates prepared based on thin film and thick film processes have large differences in film thickness, line width / line spacing, wiring accuracy, etc., which requires power devices and passive devices in the system to be packaged on different types of ceramic substrates before integration, limiting the module signal electromagnetic shielding, transmission efficiency, integration density improvement and package size reduction. More importantly, the existing thin film and thick film ceramic substrate preparation processes are incompatible (low temperature and high temperature processes), making it difficult to hybrid integrate. The integration and interconnection of the two must use wire bonding, which affects the reliability of the device. To this end, it is necessary to develop a new type of ceramic substrate, implement thin film and graphic electroplating processes on the same ceramic substrate, realize the hybrid integration of thin film / thick film ceramic substrates, and improve the integration and reliability of devices. Summary of the invention

[0004] In view of the above defects or improvement needs of the prior art, the present invention provides a thin film / thick film hybrid integrated ceramic substrate and a preparation method thereof, which realizes the integrated integration of thin film circuits and thick film circuits on the same ceramic substrate. It not only takes advantage of the advantages of electroplated ceramic substrates (DPC) such as good thermal conductivity / heat resistance, high graphic accuracy, vertical interconnection and compatibility with thin film processes, but also effectively improves the function / volume ratio and reliability of system modules.

[0005] Correspondingly, the present invention provides a thin film / thick film hybrid integrated ceramic substrate, including a thin film ceramic substrate prepared by a semiconductor thin film process and a thick film ceramic substrate prepared by a graphic electroplating process, both of which share the same ceramic substrate and are electrically connected through a surface metal layer. The thin film ceramic substrate contains thin film multilayer wiring, metal through holes and a gold-tin alloy layer, and the thick film ceramic substrate contains a thick metal layer and metal through holes.

[0006] As a further preference, the thin film multilayer wiring structure of the thin film ceramic substrate is wiring layer / dielectric film / wiring layer, the number of wiring layers is greater than 2, the film thickness is 0.1-1μm, preferably 0.2μm, the dielectric film is used as interlayer insulation, and the material is PI or BCB.

[0007] As a further preference, the thick metal layer of the thick film ceramic substrate includes a seed layer, a circuit layer and a surface treatment layer, the seed layer is titanium or chromium nickel, the circuit layer is copper, the surface treatment layer is nickel gold, and the total thickness is 30-300μm, preferably 60-100μm.

[0008] As a further preference, the metal through holes of the ceramic substrate are used as heat transfer channels, electromagnetic shielding and electrical interconnection between upper and lower layers. The metal through holes in the thin film area have an aperture of 60-100 μm, and the metal through holes in the thick film area have an aperture of 120-180 μm, and are all made of copper.

[0009] Accordingly, the present invention also provides a method for preparing a thin film / thick film hybrid integrated ceramic substrate, the method comprising the following steps:

[0010] (a) A plurality of metal through holes are prepared on a ceramic substrate by laser drilling and electroplating hole filling processes;

[0011] (b) forming a patterned seed layer on the ceramic substrate by a sputtering coating process, and forming a barrier layer 1 on the ceramic substrate by a photolithography and development process;

[0012] (c) using semiconductor processing technology to prepare thin-film multilayer wiring in the unblocked area on the ceramic substrate;

[0013] (d) removing the barrier layer 1 by a wet etching process, and forming a barrier layer 2 on the thin film multilayer wiring by photolithography and development processes;

[0014] (e) preparing a circuit layer in the unblocked area on the ceramic substrate by an electroplating process;

[0015] (f) using a surface grinding process to improve the flatness of the circuit layer, and forming a nickel-gold layer on the surface of the circuit layer by a chemical nickel-gold process;

[0016] (g) removing the barrier layer 2 by a wet etching process, and preparing a gold-tin alloy layer on the thin-film multilayer wiring by electroplating or sputtering;

[0017] (h) The thin-film and thick-film hybrid integrated ceramic substrate is obtained by stripping / etching process.

[0018] As a further preference, in steps (b) and (d), the barrier layer 1 is used to protect the thick film ceramic substrate area, and the barrier layer 2 is used to protect the thin film ceramic substrate area, and both are made on the ceramic substrate by spin coating photoresist or dry film pasting.

[0019] As further preferred, in step (c), the thin film multilayer wiring is to first prepare a first wiring layer, then spin-coat a dielectric film layer, and then prepare a second wiring layer, and the operation is repeated according to the number of wiring layers.

[0020] As further preferred, in step (f), the surface grinding process is CNC grinding, ceramic brush grinding or chemical mechanical polishing, and the surface roughness is less than 0.3 μm.

[0021] As further preferred, in step (g), the gold-tin alloy layer of the thin film ceramic substrate is used for high-quality patch, has a square or circular shape, and has a thickness of 1-7 μm, preferably 3-5 μm.

[0022] In general, compared with various existing packaging substrates, the above technical solution conceived by the present invention adopts the "semiconductor thin film process + graphic electroplating" technology to prepare a thin film / thick film hybrid integrated ceramic substrate, solves the problem of hybrid integration of power devices and passive devices, and thus significantly improves the integration and reliability of electronic systems. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a schematic diagram of a thin film / thick film hybrid integrated ceramic substrate constructed by the present invention.

[0024] Figure 2 The present invention is a process flow chart of a method for preparing a thin film / thick film hybrid integrated ceramic substrate constructed according to a preferred embodiment.

[0025] The accompanying drawings are described as follows:

[0026] Ceramic substrate 1, surface metal layer 2, thin film multilayer wiring 3, metal through hole 4, gold-tin alloy layer 5, thick metal layer 6, metal through hole 7. DETAILED DESCRIPTION

[0027] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0028] In view of the above defects or improvement needs of traditional ceramic substrates, the main purpose of the present invention is to provide a thin film / thick film hybrid integrated ceramic substrate and a preparation method thereof, in order to solve the problem of hybrid integration of thin film / thick film ceramic substrates, while significantly improving the integration and reliability of electronic systems.

[0029] Some specific embodiments are given below to explain the process flow, important mechanisms and key process conditions of the present invention in a clearer and more detailed manner.

[0030] Example

[0031] See also Figure 1 The embodiment provides a thin film / thick film hybrid integrated ceramic substrate, including a thin film ceramic substrate prepared by a semiconductor thin film process and a thick film ceramic substrate prepared by a pattern electroplating process, the two share the same ceramic substrate 1, and are electrically connected through a surface metal layer 2; the thin film ceramic substrate contains a thin film multilayer wiring 3, a metal through hole 4 and a gold-tin alloy layer 5, the thin film multilayer wiring 3 is a wiring layer / dielectric film / wiring layer / dielectric film / wiring layer, the number of wiring layers is 3, the film thickness is 0.2μm, and the dielectric film is PI insulation Insulation material, the gold-tin alloy layer 5 is located on the wiring layer, has a square shape and a thickness of 3μm, the metal through hole 4 is used for electrical interconnection between the upper and lower layers and electromagnetic shielding, is made of copper, and has an aperture of 80μm; the thick film ceramic substrate contains a thick metal layer 6 and a metal through hole 7, the thick metal layer 6 includes a seed layer, a circuit layer and a nickel-gold layer, the seed layer is titanium, the circuit layer is copper, the surface treatment layer is nickel-gold, and the total thickness is 100μm, the metal through hole 7 is used for electrical interconnection between the upper and lower layers and a heat flow transmission channel, is made of copper, and has an aperture of 150μm.

[0032] See also Figure 2 This embodiment also provides a method for preparing a thin film / thick film hybrid integrated ceramic substrate, which may include the following steps as an example:

[0033] Step 1, a plurality of defect-free copper metal through holes are prepared on a ceramic substrate 1 by laser drilling and copper electroplating filling process, wherein the metal through hole 4 of the thin film ceramic substrate has a hole diameter of 80 μm, and the metal through hole 7 of the thin film ceramic substrate has a hole diameter of 150 μm;

[0034] Step 2, a patterned seed layer (titanium / copper, thickness 0.2 μm) is formed on the ceramic substrate 1 by a sputtering coating process, and a photoresist is spin-coated on the ceramic substrate 1, and then a barrier layer 1 is formed by a photolithography and development process to protect the thick film ceramic substrate area;

[0035] (c) using semiconductor processing technology to prepare thin-film multilayer wiring 3 in the unblocked area on the ceramic substrate 1, first preparing the first wiring layer, then spin coating the dielectric film layer, and then preparing the second wiring layer, and repeating the operation according to the number of wiring layers to prepare three layers of thin-film wiring;

[0036] (d) removing the barrier layer 1 by a wet etching process, attaching a dry film on the ceramic substrate 1, and then using a photolithography and development process to form a barrier layer 2 for protecting the thin film ceramic substrate area;

[0037] (e) preparing a thick copper circuit layer in the unblocked area on the ceramic substrate 1 by a copper electroplating process;

[0038] (f) using a ceramic brushing process to improve the flatness of the circuit layer, with a surface roughness of less than 0.3 μm, and using a chemical nickel-gold process to make a nickel-gold layer on the surface of the circuit layer, to obtain a thick metal layer 6 of the thick-film ceramic substrate, with a thickness of 100 μm;

[0039] (g) removing the barrier layer 2 by a wet etching process, and preparing a square gold-tin alloy layer 5 with a thickness of 2 μm on the thin film multilayer wiring 3 by an electroplating process;

[0040] (h) The excess colloidal material is removed by a stripping / etching process to obtain a thin-film and thick-film hybrid integrated ceramic substrate.

[0041] It will be easily understood by those skilled in the art that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A thin film / thick film hybrid integrated ceramic substrate, characterized in that: It includes a thin film ceramic substrate prepared by a semiconductor thin film process and a thick film ceramic substrate prepared by a graphic electroplating process. The two share the same ceramic substrate and are electrically connected through a surface metal layer; the thin film ceramic substrate contains thin film multilayer wiring, metal through holes and a gold-tin alloy layer, and the thick film ceramic substrate contains a thick metal layer and metal through holes; the surface metal layer is obtained by depositing a metal seed layer on the ceramic substrate by a sputtering coating process.

2. A thin film / thick film hybrid integrated ceramic substrate as claimed in claim 1, characterized in that: The thin film multilayer wiring structure of the thin film ceramic substrate is wiring layer / dielectric film / wiring layer, the number of wiring layers is greater than 2, the film thickness is 0.1-1 μm, the dielectric film is used as interlayer insulation, and the material is polyimide (PI) or benzocyclobutene (BCB).

3. A thin film / thick film hybrid integrated ceramic substrate as claimed in claim 1, characterized in that: The thick metal layer of the thick film ceramic substrate comprises a seed layer, a circuit layer and a surface treatment layer, the seed layer is titanium or chromium nickel, the circuit layer is copper, the surface treatment layer is nickel gold or nickel palladium gold, and the total thickness is 30-300 μm.

4. A thin film / thick film hybrid integrated ceramic substrate as described in claim 1, wherein the metal through holes of the ceramic substrate are used as heat flow transmission channels, electromagnetic shielding, and electrical interconnection between upper and lower layers, and are made of copper with a pore size of 50-200 μm.

5. A thin film / thick film hybrid integrated ceramic substrate as claimed in any one of claims 1 to 4, characterized in that: The aperture of the metal through hole in the thin film region is 60-100 μm, and the aperture of the metal through hole in the thick film region is 120-180 μm.

6. A method for preparing a thin film / thick film hybrid integrated ceramic substrate as claimed in any one of claims 1 to 5, characterized in that: The method comprises the following steps: (a) A plurality of metal through holes are prepared on a ceramic substrate by laser drilling and electroplating hole filling processes; (b) depositing a metal seed layer on the ceramic substrate by a sputtering coating process, and forming a barrier layer 1 on the ceramic substrate by a photolithography and development process; (c) using semiconductor micromachining technology to prepare thin-film multilayer wiring in unblocked areas on a ceramic substrate; (d) removing the barrier layer 1 by a wet etching process, and forming a barrier layer 2 on the thin film multilayer wiring by photolithography and development processes; (e) preparing a circuit layer in the unblocked area on the ceramic substrate by an electroplating process; (f) using a surface grinding process to improve the flatness of the circuit layer, and forming a nickel-gold layer on the surface of the circuit layer through a surface treatment process; (g) removing the barrier layer 2 by a wet etching process, and preparing a gold-tin alloy layer on the thin-film multilayer wiring by electroplating or sputtering; (h) Through the film stripping / etching process, a thin film / thick film hybrid integrated ceramic substrate is obtained.

7. A method for preparing a thin film / thick film hybrid integrated ceramic substrate as claimed in claim 6, characterized in that: The barrier layer 1 is used to protect the thick film ceramic substrate area, and the barrier layer 2 is used to protect the thin film ceramic substrate area. Both are made on the ceramic substrate by spin coating photoresist or sticking dry film.

8. The method for preparing a thin film / thick film hybrid integrated ceramic substrate according to claim 6, characterized in that: The thin film multilayer wiring is to prepare the first wiring layer first, then spin-coat the dielectric film layer, and then prepare the second wiring layer, and the operation is repeated according to the number of wiring layers.

9. The method for preparing a thin film / thick film hybrid integrated ceramic substrate according to claim 6, characterized in that: The surface grinding process is CNC grinding, ceramic brush grinding or chemical mechanical polishing, and the surface roughness is less than 0.3 μm.

10. A method for preparing a thin film / thick film hybrid integrated ceramic substrate according to any one of claims 6 to 9, characterized in that: The gold-tin alloy layer of the thin-film ceramic substrate is used for high-quality patch, is located on the wiring layer, has a square or circular shape, and has a thickness of 1-7 μm.

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