Patent Application
20150348893
The present invention relates to methods of manufacturing a three-dimensional integrated circuit, and more particularly, to a method of manufacturing a three-dimensional integrated circuit comprising an aluminum nitride interposer.
A three-dimensional integrated circuit (3D-IC) comprises at least two integrated circuits or circuit components. They stack and electrically connect to each other in three dimensions and their interconnections between the integrated circuits or circuit components are achieved through a plurality of microvias. Hence, the three-dimensional integrated circuit comprises an interposer with a lot of microvias.
Three-dimensional integrated circuit packaging technology conventionally uses a silicon wafer as an interposer because the silicon-based semiconductor manufacturing processes are well-understood. For wafer-level heterogeneous integration, however, the compatibilities of materials between components/substrate and components/components need to be taken considerations. For example, a silicon interposer has some serious drawbacks and they need to be solved. First, there is obviously CTE (the coefficient of thermal expansion) mismatch between components and a substrate, which leads to a warpage induced by thermal stress. In addition, silicon has a poor insulation property (˜103 Ω-cm), which may further lead to phenomena of the short current or the leakage current. Devices would cause problems of signals such as coupling, noising and loss, especially under a high power or wafer stacking conditions. Hence, the manufacturing processes of a silicon interposer require an additional process of a silicon dioxide (SiO2) layer deposition as an insulator. However, this layer not only decreases the heat dissipation capability of a silicon interposer but also increases the cost of process.
A research team of the Georgia Institute of Technology first reported a glass as an interposer for packaging technique to solve the problems from silicon-based processes. Although a glass has a good electrical insulation property (1010˜1014 Ω-cm), its thermal conductivity only shows a low range of 0.8˜1.3 W/m-k, which reveals that it could be suitable for a low-power 3D chip stacking products. For high-power 3D-IC products, its poor heat conductivity would lead to a serious accumulation of heat, and further result in heat failure of components, deterioration of product reliability, and then reduction of the lifetimes of products. In view of this, it is important to develop a new material as an interposer for 3D-IC package in high power device applications.
In view of the aforesaid drawbacks of the prior art, it is an objective of the present invention to provide a method of manufacturing a three-dimensional integrated circuit comprising an aluminum nitride interposer to integrate a first circuit component, a conductive block, an aluminum nitride interposer, at least a second circuit component with each other, with a view to manufacturing a three-dimensional integrated circuit comprising an aluminum nitride interposer which manifests desirable features, such as quick heat dissipation, low warpage, low leakage current, and low noise.
In order to achieve the objectives, the present invention provides a method of manufacturing a three-dimensional integrated circuit comprising an aluminum nitride interposer. The method comprises the steps of: providing a first circuit component; providing a plurality of first conductive blocks on the first circuit component; providing an aluminum nitride interposer on the first circuit component, wherein the aluminum nitride interposer comprises a plurality of microvias each having therein a conductor with an end in contact with a corresponding one of the first conductive blocks; providing a plurality of second conductive blocks on the aluminum nitride interposer, wherein the second conductive blocks are in contact with other ends of the conductors in the microvias, respectively; and providing at least a second circuit component on the aluminum nitride interposer, wherein the at least a second circuit component is electrically connected to the first circuit component through the first and second conductive blocks and the conductors.
The first circuit component is provided in the form of a printed circuit board (PCB), but the present invention is not limited thereto. The at least a second circuit component is provided in the form of a CMOS, a DRAM, an ambient light sensor, a power amplifier, a RF and inertia MEMS, or a combination thereof, but the present invention is not limited thereto.
The aluminum nitride shows excellent physical and chemical properties, including a thermal conductivity coefficient of ˜200 W/mk, high chemical stability, and excellent electrical insulation of ˜1014 Ω-cm. According to the present invention, the interposer of the three-dimensional integrated circuit is made of aluminum nitride. The content of interposer is 80˜99.95% aluminum nitride with a thickness of 20-100 μm. According to the present invention, the aluminum nitride interposer has therein a plurality of microvias with a diameter of 5-100 μm.
The microvias of aluminum nitride interposer are formed by femtosecond laser pulses, such as a titanium-sapphire laser beam (in accordance with parameters, including a center wavelength of 800 nm, a pulse width <100 fs, a laser power of 200˜1,000 mW, and a frequency of 1,000˜10,000 Hz), but the present invention is not limited thereto, as it is also practicable for the present invention to form the microvias of an aluminum nitride interposer by wet etching or dry etching processes.
Both of the conductive blocks and the conductors are intended to electrically connect the first circuit component to the at least a second circuit component. The conductive blocks and the conductors in the microvias are conductor. The conductive blocks are provided in the form of tin balls, but the present invention is not limited thereto. The conductors are made of copper, tungsten, silver, tin or conductive paste, but the present invention is not limited thereto.
The above overview, the following description, and the accompanying drawings are intended to illustrate the technical solution and means for use in achieving the objectives of the present invention as well as the advantages thereof. The other objectives and advantages of the present invention are described below and illustrated with the accompanying drawings.
Objectives, features, and advantages of the present invention are hereunder illustrated with specific embodiments in conjunction with the accompanying drawings, in which:
The present invention provides a method of manufacturing a three-dimensional integrated circuit comprising an aluminum nitride interposer. The method essentially entails: performing drilling and copper filled via processes on an 8-inch or 12-inch aluminum nitride wafer to form an aluminum nitride interposer; and connecting chips to a printed circuit board (PCB) with tin balls by alignment and connection technologies, and its package structure is schematically depicted with
Referring to
The present invention provides a method of manufacturing a three-dimensional integrated circuit comprising an aluminum nitride interposer with a view to manufacturing a three-dimensional integrated circuit for use with a high-power component. In this regard, aluminum nitride shows excellent properties of insulation and heat dissipation compared to several conventional interposer materials, such as silicon and glass. For a comparison of the properties of three different substrates (silicon, glass, and aluminum nitride), see Table 1 below.
In this embodiment, microvias are formed in the aluminum nitride interposer by a femtosecond laser. Specifically speaking, the microvias 140 are formed in the aluminum nitride interposer 120 by a titanium-sapphire laser. The titanium-sapphire laser-based drilling process is performed in accordance with the following parameters: a pulse width <100 fs, a frequency of 1,000˜10,000 Hz, a center wavelength of 800 nm, a platform moving speed of 20-200 μm/s, and a laser power of 200-1000 mW. Therefore, microvias 140 with an aspect ratio >5 can be fabricated.
The present invention is disclosed above by preferred embodiments. However, persons skilled in the art should understand that the preferred embodiments are illustrative of the present invention only, but should not be interpreted as restrictive of the scope of the present invention. Hence, all equivalent modifications and replacements made to the aforesaid embodiments should fall within the scope of the present invention. Accordingly, the legal protection for the present invention should be defined by the appended claims.
