Set the coefficients of some materials.
SYNOPSIS
- material
-
( silicon | oxide | poly | oxynitr | nitride | photores | aluminum )
[ ( wet | dry ) ]
[ Ni.0 = n ] [ Ni.E = n ] [ Ni.Pow = n ]
[ eps = n ]
[ visc.0 = n ] [ visc.E = n ] [ visc.x = n ]
[ Young.m = n ] [ Poiss.r = n ]
[ lcte = string ] [ intrin.sig = n ]
[ act.a = n ] [ act.b = n ] [ ( n.type | p.type ) ]
DESCRIPTION
This statement allows the user to specify values for coefficients of the intrinsic concentration and relative permittivity for all the materials.
- silicon | oxide | oxynitride | nitride | poly | photores | aluminu
- These parameters indicate the material that the remainder of the parameters apply to.
- wet | dry
- These parameters indicate whether the parameters apply to in wet or dry oxides. When oxide is specified, it also necessary to specify the type of oxide.
- Ni.0, Ni.E, Ni.Pow
- These parameters specify the dependencies of the intrinsic electron concentration as a function of temperature.
Ni.0 is the pre-exponential term, Ni.E is the activation energy, and Ni.pow is the power dependence of temperature. The default in silicon is 3.9E16 cm3 for Ni.0, 0.605 eV for Ni.E, and 1.5 for Ni.Pow.
- eps
- This parameter allows the specification of the relative permittivity of the different materials.
- visc.0, visc.E, visc.x
- These are the parameters specifying viscosity. visc.0 is the pre-exponential coefficient, visc.E is the activation energy. visc.x is the incompressibility factor. Normally this is left at the value of 0.499 (0.5 is infinitely incompressible), but if it is desired to allow more compressibility, it can be lowered.
- Young.m, Poiss.r
- Young.m is the material's Young's modulus, in dynes/cm2. Poiss.r is the material's Poisson ratio.
- lcte
- This is an expression giving the linear coefficient of thermal expression as a function of temperature, called T in the expression. It is given as a fraction, not as a percentage.
- intrin.sig
- This parameter specifies the initial uniform stress state of a material such as a thin film of nitride deposited on the substrate. It can be specified as a function of temperature by using an expression and the variable T (see the examples below).
- act.a, act.b
- GaAs activation modeling includes a compensation mechanism. This is modeled in SUPREM-IV.GS using the following expression:
Where A and B in the above expression are set by the act.a and act.b parameters. act.a and act.b may be expressions in terms of T, the temperature in degrees C. The values of A and B are dependent upon the local dominant impurity type so that one of the p.type or n.type parameters must be specified when specifying act.a or act.b.
- n.type, p.type
- When setting the GaAs activation coefficients using the act.a and act.b parameters, one of the n.type or p.type parameters must be specified to indicate the type of region that they are to apply to.
EXAMPLES
- material silicon eps = 11.9
- This statement specifies the silicon relative permittivity.
- mate nitride lcte=(3e-6+2*1e-10*T) intrin.sig=1.4e10 You=3e12
- This statement gives the thermal expansion coefficient of nitride as a function of absolute temperature T. Thus at 0K the coefficient is 0.0003%/K. The initial stress in the nitride film is 1.4E10 dynes/cm2 and the Young's modulus is 3.0E12 dynes/cm2.
BUGS
There is limitation in the kind of temperature dependence ni can take on. It is limited to expressions of the form above. It should be done in the same fashion as the coefficient of expansion.
SEE ALSO
The oxide,
stress,
and diffuse statements.