BICMOS TECHNOLOGY SEMINAR REPORT PDF

However it took 30 years before this idea was applied to functioning devices to be used in practical applications, and up to the late this trend took a turn when MOS technology caught up and there was a cross over between bipolar and MOS share. Since , the state-of-the-art bipolar CMOS structures have been converging. Because the process step required for both CMOS and bipolar are similar, these steps cane be shared for both of them. Over the last decade, the integration of analog circuit blocks is an increasingly common feature of SOC development, motivated by the desire to shrink the number of chips and passives on a PC board. This, in turn, reduces system size and cost and improves reliability by requiring fewer components to be mounted on a PC board.

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This lower doped substrate increases the susceptibility for latchup. To improve latchup immunity retrograde N-well doping is used. The retrograde doping can be either achieved by high energy ion implantation or by using buried layers. With the first approach no epitaxial layer is required, but ion implantation damage has to be considered. By using buried layers a relatively thick and expensive epitaxial layer has to be grown on top of the substrate.

The epitaxial deposition process must be optimized to reduce material defects and minimize autodoping. Due to the usage of the buried layers the well drive-in has to be optimized for bipolar collector requirements. The first one minimizes the Kirk effect, where the second one ensures higher collector-base breakdown voltage. The CMOS device on the other hand requires a sufficiently high concentration below the surface to avoid punchtrough, especially as device dimensions are shrinking.

Practically, the various conflicting requirements have to be balanced. This leads to steeper collector N-well profiles which cause an increase of the collector series resistance. The doping for the emitter junction is usually provided by a N- type implant into the polysilicon, which forms the emitter-base contact during the source-drain anneal of the CMOS device by outdiffusion.

The pattern is etched in a 50nm thick oxide covering the substrate. The structure before the antimony implantation is shown in Figure 1. Afterwards, a high temperature anneal is performed to remove damage defects and to diffuse the antimony into the substrate.

Therefore, the nitride mask is selectively removed and the remaining oxide serves as blocking mask for the buried P-layer implant see Fig. Figure 2: Device cross-section of BiCMOS process showing P buried layer self aligned implant After removing all oxide a thick epitaxial layer with intrinsic doping is grown on top see Fig. Therefore, the same masks are used as for the buried layers.

The subsequent P-well implant is self-aligned to the well edge see Fig. As compared to conventional CMOS a relatively short well drive-in min is performed at with the oxide cap in place. Previously, the N-wells were implanted and a nm oxide is grown, which serves as blocking mask for the P-well implant. After the wells are fabricated the whole wafer is planarized and a pad oxide is grown. The oxide is capped with a thick nitride. After patterning the active regions of the device, an etch step is used to open up the field isolation regions.

Prior to field oxidation, a blanket channel stop is implanted see Fig. Before, the wafer was planarized and patterned. Oxidation is used to fabricate a nm thick field oxide. To minimize buried layer diffusion the oxidation temperature is quite moderate. Therefore, phosphorus is implanted into the N-well of the collector region see Fig.

We continue with the fabrication of the intrinsic base for the bipolar device. Therefore, the base region is opened and the base implant is performed. To ensure low base-emitter capacitance a thicker gate oxide is deposited after the base implant.

This oxide will also serve as implantation shelter for the base region caused from the CMOS threshold implants. The deposited oxide has to be removed from the non base regions by an etch step. The structure after the intrinsic base implant and prior to the base oxide deposition is shown in Figure 8.

The emitter window is opened, followed by the polysilicon deposition. The polysilicon is implanted and will serve as outdiffusion source to form the emitter junction. We proceed with the resist strip and perform a pre-gate oxide etch to clean the oxide surface. A 20nm thick gate oxide is grown on top. The active emitter window is patterned and opened up with an etching process until the whole gate oxide is removed in the emitter region.

Then a polysilicon layer is deposited, which forms the emitter contact as well as the gate polysilicon layers.

This polysilicon layer is implanted with arsenic which will diffuse out from the polysilicon layer at the final source-drain anneal to form the emitter junction see Fig.

The subcollector is opened to collect additional N-type doping. Again, phosphorus is implanted into the subcollector region. The polysilicon layer is patterned to define the CMOS gates and the bipolar emitter. After emitter formation, all subsequent process steps are well known from CMOS technology. Then the sidewall spacer formation is initiated. Therefore, an oxide layer is deposited and anisotropically etched back.

Next, the source-drain regions are heavily doped by phosphorus and boron, which is depicted in Figure 11 and Figure 12, respectively. Finally, the fabrication of the active regions is finished by the source- drain anneal, which is optimized for outdiffusion conditions of the bipolar device. Hence, a 15s long RTA anneal at is performed. The final device structure including the active area dopings is shown in Figure The source-drain anneal is optimized to emitter outdiffusion conditions.

Afterwards the structure is scheduled for a double-level interconnect process. A production 0. Utilizing both shallow and deep trench isolation, a self-aligned SiGe NPN is formed after most of the standard dual-gate 0. Self-aligned extrinsic base implants enable optimization of extrinsic base resistance while maintaining a simple bipolar structure. After removal of the sacrificial emitter and pre- clean steps, an in-situ doped poly emitter is deposited in an RT-CVD reactor and patterned.

The SiGe process continues with 4 layers of standard metallization, thin film metal resistor, and MIM capacitor plus 2 thick layers of aluminum 1. Increased RF sub- system functionality is driving new architectures, like direct conversion radios, which reduce the dependence on off-chip components while the requirements of next generation products are more demanding in terms of noise figure, gain, linearity and power consumption than the current generation.

Physical layer products for 10G and 40G systems have migrated to more highly integrated SiGe BiCMOS designs that have increased functionality, reduced power and reduced cost. Increased data density in disk drives is leading to a need for higher data rate and greater sensitivity pre-amplifiers that require SiGe BiCMOS. Developing standards, such as Ultra-Wide-Band for wireless data, can exploit the performance offered by SiGe BiCMOS to meet the GHz frequency requirements while meeting power and cost targets consistent with a consumer application.

GEOVISION LPR PDF

Seminar Report-Bicmos technology

However it took 30 years before this idea was applied to functioning devices to be used in practical applications, and up to the late this trend took a turn when MOS technology caught up and there was a cross over between bipolar and MOS share. Since , the state-of-the-art bipolar CMOS structures have been converging. Because the process step required for both CMOS and bipolar are similar, these steps cane be shared for both of them. Over the last decade, the integration of analog circuit blocks is an increasingly common feature of SOC development, motivated by the desire to shrink the number of chips and passives on a PC board. This, in turn, reduces system size and cost and improves reliability by requiring fewer components to be mounted on a PC board.

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