BJT-Integrated PIP Capacitor for BiCMOS Compatibility

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Solution Overview

Problem

Conventional capacitor structures in the MOS process, such as MIM and MIS capacitors, are not compatible with the bipolar complementary metal-oxide-semiconductor (BiCMOS) process and lack a code option, making it necessary to develop a poly-insulator-poly (PIP) capacitor structure integrated with a bipolar junction transistor (BJT) for compatibility and cost-effectiveness.

Innovation Solution

A PIP capacitor structure is integrated with a BJT, featuring a substrate with distinct regions for the BJT and PIP capacitor, where the base and isolation layers extend to form a PIP capacitor, and a method is proposed to form this structure, including the formation of a gate material layer, patterning, and the creation of a salicide layer to define a tunable resistance, enabling the formation of a capacitor array and input RC circuit.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If conventional MIM or MIS capacitor structures are used in MOS process, then the capacitor can be formed with existing processes, but the structure cannot provide code option and is not compatible with BiCMOS process

Engineering Contradiction:

Improvecompatibility with BiCMOS process and code optionVSAvoidmanufacturing process complexity

Core Design Contradiction:

Adaptability or versatilityVSEase of manufacture

Solution Approach 1:

The patent merges the PIP capacitor structure with the BJT structure by sharing common layers (base poly layer and isolation layer). The base poly layer of the BJT serves as one electrode of the PIP capacitor, and the isolation layer serves as the dielectric, eliminating the need for separate capacitor fabrication processes and enabling compatibility with BiCMOS technology.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The base poly layer and isolation layer serve dual functions: they form the base region of the BJT and simultaneously constitute the electrode-dielectric structure of the PIP capacitor. This multi-functionality allows a single structure to provide both transistor and capacitor functionality, enabling code options in BiCMOS processes.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Adaptability or versatility

If separate capacitor structures are added to BiCMOS process, then code option is provided, but the process complexity and manufacturing cost increase

Engineering Contradiction:

Improvecode option capabilityVSAvoidprocess steps and structure

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent combines the capacitor formation process with the existing BJT fabrication process. The PIP capacitor is formed as an integral part of the BJT structure during the same processing steps, eliminating the need for additional separate capacitor fabrication processes and reducing overall device complexity.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The same base poly layer and isolation layer are used for both BJT operation and capacitor formation. This universal use of existing structure elements provides code option capability without adding extra process steps or structural complexity.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Data Source

PatentUS8193605B2Bipolar junction transistor integrated with PIP capacitor and method for making the same

Publication Date: 2012.06.05 UNITED MICROELECTRONICS CORP

AI summary

A bipolar junction transistor (BJT) integrated with a PIP capacitor includes a substrate including a bipolar junction transistor region and a PIP capacitor region, a bipolar junction transistor disposed in the bipolar junction transistor region and extending an isolation layer to the PIP capacitor region and a base poly layer disposed on the isolation layer, and a PIP capacitor disposed in the PIP capacitor region and including a lower poly layer, the isolation layer and the base poly layer to selectively form a PIP capacitor.