Properties of SiO2 and Si3N4 at 300K  

        

Dielectric layers are just as indispensable to integrated circuit fabrication as the semiconductor itself and interconnecting metallization.  Dielectric layers are used primarily to isolate active circuits from each other and to provide mechanical and chemical protection to the device itself.  Dielectric layers are also widely used in the fabrication of components essential to circuit functionality such as capacitors and MOS transistors.  Lastly, dielectric layers are also used as masking materials during wafer fabrication itself.

                            

Two dielectric workhorses in device fabrication are the silicon dioxide (SiO2) and the silicon nitride (Si3N4).  Aside from being used for masking purposes, the former is extensively used in electrical isolation and as capacitor dielectric and MOS gate oxide while the latter is widely used as the final glassivation layer of the die.  The properties of SiO2 and Si3N4 at 300 deg K are presented in Table 1.

            

             

Table 1. Properties of Silicon Dioxide (SiO2) and Silicon Nitride (Si3N4) at 300K

Properties

SiO2

Si3N4

Structure

Amorphous

Amorphous

Melting Point (deg C)

approx. 1600

---

Density (g/cm3)

2.2

3.1

Refractive Index

1.46

2.05

Dielectric Constant

3.9

7.5

Dielectric Strength (V/cm)

107

107

Infrared Absorption Band (m)

9.3

11.5 - 12.0

Energy Gap at 300K (eV)

9

approx. 5.0

Linear Coefficient of Thermal Expansion,

ΔL/L/ΔT (1/deg C)

5 x 10-7

---

Thermal Conductivity at 300 K

(W/cm-degK)

0.014

---

DC Resistivity at 25 C (ohm-cm)

1014 - 1016

approx. 1014

DC Resistivity at 500C (ohm-cm)

---

2 x 1013

Etch Rate in Buffered HF (angstroms/min)

1000

5 - 10

   

   

LINKS:  Dielectric Glassivation Thermal OxidationSi, Ge, GaAs Properties

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