Self-aligned SiGe HBT Fabrication for BiCMOS Integration
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Solution Overview
Problem
The integration of bipolar transistors with CMOS technology is limited by parasitic capacitance and increased base resistance, which negatively affect device performance, and existing methods are not fully compatible with CMOS processing or require excessive additional steps.
Innovation Solution
A fully self-aligned SiGe hetero-junction bipolar transistor (HBT) is fabricated using two additional masks, minimizing parasitic collector-base and emitter-base capacitance and base resistance by aligning the emitter-definition and extrinsic base connection with the bipolar active area, and embedding the process within a CMOS flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If bipolar transistors are integrated with CMOS technology, then device functionality is improved, but parasitic capacitance increases and base resistance increases
Solution Approach 1:
The patent applies preliminary action by defining the bipolar active area and forming spacers before depositing the SiGe base layer. This pre-positioning of structural elements ensures that subsequent alignment steps automatically achieve proper positioning, minimizing parasitic capacitance between collector-base and emitter-base regions while maintaining compatibility with CMOS processing flows.
Solution Approach 2:
The patent implements self-service through self-aligned fabrication where previously deposited structures (spacers, active areas) automatically serve as alignment references for subsequent layers. The extrinsic base connection and emitter definition are self-aligned to the bipolar active area, eliminating the need for additional alignment steps and minimizing parasitic effects without requiring complex external alignment procedures.
2Adaptability or versatility
If bipolar transistors are integrated with CMOS technology, then device functionality is improved, but base resistance increases
Solution Approach 1:
The patent applies preliminary action by defining the bipolar active area and forming spacers before depositing the SiGe base layer. This pre-positioning of structural elements ensures that subsequent alignment steps automatically achieve proper positioning, minimizing parasitic capacitance between collector-base and emitter-base regions while maintaining compatibility with CMOS processing flows.
Solution Approach 2:
The patent implements self-service through self-aligned fabrication where previously deposited structures (spacers, active areas) automatically serve as alignment references for subsequent layers. The extrinsic base connection and emitter definition are self-aligned to the bipolar active area, eliminating the need for additional alignment steps and minimizing parasitic effects without requiring complex external alignment procedures.
3Reliability
If existing bipolar fabrication methods are used, then bipolar transistor performance is improved, but compatibility with CMOS processing is reduced and additional process steps increase
Solution Approach 1:
The patent applies universality by designing a fabrication process that serves multiple functions within a single integrated flow. The self-aligned bipolar transistor fabrication is embedded within the standard CMOS processing sequence, allowing the same fabrication platform to produce both CMOS and bipolar devices with high performance and minimal additional process steps.
Solution Approach 2:
The patent applies preliminary action by defining the bipolar active area and forming spacers before depositing the SiGe base layer. This pre-positioning of structural elements ensures that subsequent alignment steps automatically achieve proper positioning, minimizing parasitic capacitance between collector-base and emitter-base regions while maintaining compatibility with CMOS processing flows.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach reduces parasitic capacitance and base resistance while maintaining compatibility with CMOS processing, enhancing device performance without requiring complex additional steps, making it suitable for BiCMOS integration.
Implementation Method 1
Self-aligned epitaxially grown bipolar transistor
Data Source
AI summary
The illumination system has a light source (1) with a plurality of light emitters (R, G, B). The light emitters comprise at least a first light-emitting diode of a first primary color and at least a second light-emitting diode of a second primary color, the first and the second primary colors being distinct from each other. The illumination system has a facetted light-collimator (2) for collimating light emitted by the light emitters. The facetted lightcollimator is arranged along a longitudinal axis (25) of the illumination system. Light propagation in the facetted light-collimator is based on total internal reflection or on reflection at a reflective coating provided on the facets of the facetted light-collimator. The facetted light-collimator merges into a facetted light-reflector (3) at a side facing away from the light source. The illumination system further comprises a light-shaping diffuser (17). The illumination system emits light with a uniform spatial and spatio-angular color distribution.