Bipolar transistor fabrication new new new

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1. Abdur Rehman Malik (2K22/EC/10)
132
Integrate Circuit
Fabrication

2. Topic
Bipolar transistor fabrication
Integrated circuit capacitors

3. INTRODUCTION
Steps Involved
132
Bipolar transistor fabrication
Bipolar junction transistors (BJTs) are fundamental components in electronic circuits, used for
amplification and switching purposes. Fabricating bipolar transistors involves several steps,
typically in a semiconductor fabrication facility. Here's a simplified overview of the process:
1.Substrate Selection:
2.Epitaxial Growth:
3.Oxidation
4.Photolithography
5.Etching
6.Doping
7.Metallization
8.Passivation
9.Testing and Packaging

4. 1.Substrate Selection:
2.Epitaxial Growth:
The process typically starts with a silicon wafer
substrate. The substrate undergoes thorough cleaning
to remove impurities and contaminants.
An epitaxial layer is grown on the substrate to create the
starting material for the transistor. This layer is doped to
create the necessary electrical properties for the
transistor's different regions: emitter, base, and collector.

5. 3. Oxidation:
First step is Collector Region
Require low resistivity path for the Ic
Buried N+ layer provides a low resistance path in the active collector
region
For fabrication an NPN transistor, begin with a P-type Si Substrate
(Resistivity of typically 1 ohm-cm)
N-type buried layer is diffused into the substrate
Slow diffusing material arsenic or antimony is used.
Then an epitaxial layer of lightly doped Si is grown on the P-type substrate
by placing the wafer in the furnace at 1200°C and introducing
Phosphorous
A thin layer of silicon dioxide (SiO2) is grown or deposited
on the epitaxial layer. This oxide layer acts as an insulator
and helps isolate different regions of the transistor.

6. 4.Photolithography
5.Etching
Photolithography is used to define the transistor's structure
on the wafer. A photoresist material is applied to the oxide
layer, exposed to UV light through a photomask containing
the desired transistor pattern, and developed to create a
stencil for subsequent processing steps.
Etching processes, such as wet etching or plasma etching, are
used to selectively remove material from the oxide layer
according to the pattern defined by the photoresist. This step
defines the emitter, base, and collector regions of the transistor.

7. 6.Doping
7.Metallization
Dopant atoms are introduced into specific regions of the
transistor structure to modify its electrical properties. Ion
implantation or diffusion techniques are commonly used for
doping, depending on the desired doping profile and
transistor design. For an NPN transistor, the emitter is
heavily doped with an N-type dopant, the base is lightly
doped with a P-type dopant, and the collector is moderately
doped with an N-type dopant.
Metal contacts are deposited onto the wafer to make electrical
connections with the doped regions of the transistor. Metals like
aluminum or copper are commonly used for this purpose.

8. 8.Passivation
9.Testing and Packaging
A passivation layer is applied over the wafer to protect the
transistor from environmental factors and ensure long-term
reliability. The passivation layer may consist of materials
such as silicon nitride or silicon dioxide.
After fabrication, the transistors undergo electrical testing to
ensure that they meet performance specifications. The wafer is
then diced into individual transistor chips, which are packaged
into various electronic components for integration into circuits

9. INTRODUCTION
Steps Involved
Integrated circuit capacitors
Integrated circuit (IC) capacitors are crucial components in electronic circuits, providing
energy storage, filtering, decoupling, and timing functions. They are manufactured using
processes compatible with semiconductor fabrication techniques, allowing them to be
integrated seamlessly with other electronic components on a single chip. Here's an overview
of how integrated circuit capacitors are typically fabricated:
1.Dielectric Layer Deposition:
2.Bottom Electrode Formation:
3.Dielectric Patterning
4.Top Electrode Formation
5.Patterning and Etching:
6.Isolation
7.Passivation
8.Metal Interconnects
9.Testing and Packaging

10. 1.Dielectric Layer Deposition:
2.Bottom Electrode Formation
The fabrication process begins with depositing a dielectric layer onto the semiconductor
substrate. Common dielectric materials include silicon dioxide (SiO2), silicon nitride (Si3N4), and
various high-k dielectrics such as hafnium oxide (HfO2) or aluminum oxide (Al2O3). The choice of
dielectric depends on factors like desired capacitance density, breakdown voltage, and process
compatibility.
After depositing the dielectric layer, a conductive bottom electrode is formed on top of it. This
electrode serves as one of the capacitor's plates and is typically made of a metal like aluminum
(Al), copper (Cu), or tungsten (W).

11. 3.Dielectric Patterning
4.Top Electrode Formation
Photolithography techniques are used to pattern the dielectric layer, defining the area where the
capacitor will be formed. A photoresist material is applied, exposed to UV light through a
photomask, and then developed to create a stencil for etching the dielectric layer.
Once the dielectric layer is patterned, a second conductive layer is deposited to form the
capacitor's top electrode. This layer is typically made of the same metal as the bottom electrode.
5.Patterning and Etching
Photolithography is used again to define the shape and size of the top electrode. The excess metal
is then etched away using techniques like wet etching or plasma etching, leaving behind the top
electrode.

12. 6.Isolation
7.Passivation:
Depending on the design and layout of the integrated circuit, additional isolation structures may be
implemented to prevent interference between adjacent capacitors or other components on the
chip. These isolation structures can include shallow trench isolation (STI) or other isolation
techniques.
A passivation layer is deposited over the entire surface of the integrated circuit to protect the
capacitor and other components from environmental factors like moisture and contamination.
Silicon nitride or silicon dioxide are commonly used as passivation materials.
8.Metal Interconnects:
Metal interconnect layers are deposited and patterned to provide electrical connections between
the capacitor and other components on the integrated circuit. These interconnect layers typically
consist of metals such as aluminum, copper, or tungsten.

13. 9.Testing and Packaging
After fabrication, the integrated circuit undergoes electrical testing to ensure that the capacitors
and other components meet performance specifications. The IC is then packaged into a protective
housing, often with leads for external connections, to form a complete electronic device.

14. Thankyou
Abdur Rehman Malik (2K22/EC/10)