1 Introduction
With the development of electronic technology, semiconductor manufacturing process from entering the micron -nanometer process , integration of active electronic components will be substantially improved, even with a significant increase relative to the active component of the demand for passive components . Market development trend of electronic products for light, small , so the ability to enhance the semiconductor manufacturing process , so that the number of active components within the same volume surge , in addition to supporting a significant increase in the number of passive components , also need to have more space to place these passive components, so the volume will increase the size of the overall package of the device, which is very different market trends . From a cost perspective, the relationship between the total cost proportional to the number of passive components, so the premise of passive components in large quantities to use, how to reduce the cost and space of passive components , passive components and even improve the performance , is the most one of the important topics .
IPD (Integrated Passive Devices integrated passive components ) technology to integrate multiple electronic functions such as sensors, RF transceivers , MEMS MEMS, power amplifiers, power management units and digital processors , providing a compact integrated passive devices IPD products, with miniaturization and improve system performance advantages. So , whether it is to reduce the overall size and weight of the product , or to increase functionality within the existing product volume , integrated passive component technology can play a significant role.
In the past few years , IPD technology has become a system in package (SiP) is an important way to achieve , IPD technology will "go beyond Moore 's Law" pave the way for the integration of multi-functional ; Meanwhile , PCB processing can introduce IPD technology , by integrating the advantages of IPD technology can bridge the widening gap between the package and PCB technology gap.
IPD integrated passive component technology , from the initial commercial technology has been developed to replace the current discrete passive components, steady growth in the ESD / EMI, RF, high-brightness LED and digital hybrid circuit industry driven .
2 film IPD technology introduction
IPD technology , process technology based on the process can be divided into thick and thin film manufacturing process , which has thick film process technology using ceramic substrate LTCC LTCC (Low Temperature Co-firedCeramics) technology based on high-density interconnect PCB HDI printed circuit board embedded passive components (Embedded Passives) technology ; while film IPD technology , the use of common semiconductor technology production lines and capacitors, resistors and inductors .
LTCC technology utilizes a ceramic material as the substrate , the capacitor . Resistors and other passive components embedded in the ceramic substrate by sintering the ceramic elements form an integrated , space components can be greatly reduced , but the number of layers increases , the higher the difficulty and cost of production , and therefore most of the LTCC for a particular element circuit functions ; PCB HDI technology embedded components commonly used in digital systems , in which the system is only applicable to distributed capacitance and resistance in the low precision assembly and welding , with volume reduction components , SMT equipment is not easy treated small components. Although embedded printed circuit board technology is the most mature , but poor product characteristics , tolerances can not accurately grasp, because components are difficult to replace or repair the adjustment after being buried in a multilayer , the problem occurs . Compared LTCC technology embedded components and PCB technology , thin film integrated circuit IPD technology, with high accuracy, high repeatability, small size, high reliability and low cost , the future will become the mainstream of IPD , this article will focus on film IPD technology are introduced.
3 Current Development thin film integrated passive component technology
IPD technology uses a film exposure, development , coating , diffusion, thin film etching process , a representative cross section of a thin film integrated passive process shown in Figure 1 , this process can produce a variety of resistance . Capacitive and inductive components, and low inductance ground plate and passive components of the transmission line connecting traces . Film structure fabricated on a suitable carrier substrate materials, processes necessary to meet the performance and accuracy index components required , can not be complex, requiring fewer number of masks ( generally 6 to 10 ) . Each passive element typically occupy less area of 1 mm2 in order to compete with surface mount technology components in the discrete area and cost.
According to IPD existing structures to develop vendors were introduced as follows :
(1) Telephus
IPD Telephus development of thick copper process , the process can improve the performance of the line has only passive components . Reduce costs and reduce the size , such as filters and division , a thick layer of copper (10 mm) , and silicon on insulator surface and integration of the wireless communication system having a high performance RF module , and the low dielectric constant material is suitable for reducing the metal the parasitic capacitance between the layers , the structure shown in FIG 2 the IPD .
(2) IMEC
IMEC thin film technology is also used as the connection lines of copper plating , BCB as the dielectric layer , Ni / Au layer serving as the connection end surface of the metal , using up to four layers of the metal layer . IPD its structure shown in Figure 3.
(3) Dai Nippon
IPD resistor Dai Nippon development in Ti / Cr -based, capacitor formed by anodic oxidation process of Ta2O5 , inductors designed for microstrip lines and spiral inductors , copper-based lines . Figure 4 shows the structure of the IPD .
(4) SyChip
IPD SyChip TaSi development of resistance to the material , the capacitor dielectric material of Si3N4, the upper electrode is Al, the lower electrode TaSi, and the line inductors are made of aluminum material . IPD its structure as shown in Figure 5 .
4 thin film integrated passive component technology and process structure
The biggest difference with the thick film process is that the process produced the film thickness , the so-called thick-film thickness is generally more in 5μm ~ 10μm or more, and the thickness of thin film process produced between about 0.01μm ~ 1μm .
If the use of thin-film process resistors, capacitors, inductors elements formed simultaneously , require different processes and materials to produce. Thin-film technology in the semiconductor integrated circuit manufacturing process, technology is already quite mature, so the integration process during the time , just pay attention to the compatibility between the different components of the material, the design process can be reached .
Overall, the integrated passive device IPD film may be due to the different product applications , formed on different substrates , a silicon wafer substrate optional . Alumina ceramic substrate , a glass substrate , a thin film integrated passive components IPD technology can be integrated thin-film resistors. Capacitance and inductance in one of its process technology development , comprising: a photolithography techniques, thin film deposition and processing techniques , etching techniques , electroplating processing technology , electroless plating processing technology , the processing flow shown in Figure 6 . In addition to the integration of passive components on a silicon wafer manufacturing process can also be combined with active components, passive components and active components integrated circuit to achieve multi-functional needs. Here thin film resistors . Capacitance and inductance , respectively, for a brief processing .
( 1 ) a thin film resistor processing
The thin film resistor is typically produced by the sputtering process , the plating on resistive material on the insulating substrate , and then etching using the photoresist technique , a process to obtain the resistance value of the resistance pattern design , which process schematic shown in Figure 7 .
In the use of materials, need to consider that the rate of TCR resistor material change in resistance at different temperatures . The thin film resistor is formed with a vacuum vapor deposition, sputtering , plating , and thermal decomposition , and the resistive material used is a metal comprising a single component . Alloys and metal-ceramic categories.
( 2 ) film capacitors processing
Because MIS (Metal-Insulator-Semiconductor metal - insulator - semiconductor structures ) film capacitors using semiconductor as the bottom electrode , the capacitor itself has a parasitic resistance , resulting in lower resonant frequency components , can not be applied more than the rate of 200 MHz , so the high frequency applications it is necessary to select MIM (Metal-Insulator-Metal metal - insulator - Semiconductor ) film capacitors , MIM capacitors can reduce the parasitic resistance value , thereby increasing the resonant frequency element , and the resonance frequency of the dielectric material is determined from the frequency of vibration . Like the thin-film resistors , capacitors film capacitors need to consider the rate of change , and the dielectric constant need to be considered.
Also, note that the surface roughness of the substrate is Ra <0.3 μm, when the roughness Ra exceeds the predetermined range , the dielectric layer is likely to be the bottom electrode protruding mound (Hill Lock) penetrate a short circuit .
( 3 ) thin film inductors processing
Thin film inductor process and resistor process is similar but the main design consideration is how to reduce the parasitic capacitance and increases the quality factor (Q) components , the inductance characteristic ratio , considering reducing the DC resistance to increase demand Q value , the inductance of the wire thickness must be between 5 μm ~ 10 μm, it is usually formed by electroplating wire inductance to meet the needs of the manufacturing process .
The surface roughness of the substrate will affect the characteristics of the thin film inductor , especially at high frequencies , the high surface roughness is likely to cause increased noise , resulting in reduced high-frequency characteristics , so the choice of the substrate, affect the production and processing the performance of the membrane element .
Impact of technology on the PCB 5 IPD technology development
As technology advances , PCB printed circuit board in the direction of greater accuracy and higher -density development, but a gradual and highly integrated IC packaging field , passive component integration in line with the development trend of today's electronic systems , IPD technology has become the system a -level package (SiP) is an important way to achieve .
IPD integrated passive component technology with high wiring density , small size, light weight ; highly integrated, can be embedded resistors, inductors, capacitors and other passive components and active chips ; good high-frequency characteristics , can be used for microwave and millimeter-wave fields and so on. The film IPD integrated passive components used in PCB processing technology to achieve the savings package size , improved signal transmission performance , reduce costs , improve reliability purposes ; By integrating the advantages of IPD technology, packaging technology to bridge the widening gap between technology and PCB gap, can effectively reduce the volume and weight of electronic machine with the system , and has broad market prospects.
IPD integrated passive components on PCB processing applications , the choice of the high thermal conductivity of the metal , diamond, ceramic or aluminum - silicon carbide composite materials such as substrates , manufacturing and high -power -density multilayer circuit board , and should strengthen the IPD passive integrated PCB board process improvement, improvement of material properties and cost reduction , as well as speeding up the application in microwave communications, high-density integration and high-power fields.
6 Conclusions
IPD film integrated passive component technology can integrate multiple electronic functions , has the advantage of miniaturization and improve system performance , can replace bulky discrete passive components. Meanwhile , PCB processing IPD technology can be introduced through the IPD technology integration advantages can bridge the widening gap between the package and PCB technology technology gap.
The rapid development of thin film integrated passive components IPD technology, the passive integration technology into a practical and industrialization phase, a new generation of integrated passive components and related technology will be widely used in aerospace , military, medical , industrial and communications and other fields of the electronics industry , so the development of IPD technology , both for the development of the enterprise itself or to enhance the competitiveness of the domestic industry has an important significance.
