Integrated TaN Resistors

ATP offers a wide variety of TaN sheet resistivities from 10–200 ohms/square. Our standard and most cost effective sheet resistivities are 50, 75, and 100 ohms/square. Standard tolerances for resistors are ± 10%. With laser trimming tolerances as low as ± 0.5% can be achieved. With Laser trimming additional tooling and time will be required. Please download document #50025 “Laser Resistor Trimming Design Rules” in PDF format (requires Adobe Reader).

Basic equation for calculating resistance

The resistance of a specific resistor depends on its aspect ratio (the ratio of its length to width) expressed as a number of “squares” (note: the term “square” is dimensionless).

R = s(L/W)

Where: R = resistance in ohms

s = sheet resistance in ohms/sq

L = Length of the resistor

W = width of the resistor

Resistor “length” is always the dimension of the resistor parallel to the current flow.

The resistor “square” in the corner area of a bent style resistor should be counted as one-half the value of the sheet resistance.

Resistor Types

Square or Rectangular Configuration: The most common type of resistor.

L or Bent Configuration: The resistor “square” in the corner area(s) of a bent style resistor (e.g. an “L” shape or serpentine design) should be counted as one-half the value of the sheet resistance.

Serpentine Configuration: This resistor is typically used for high value resistors. The number of corners complicates calculation of the value. The resistor “square” in the corner areas of a serpentine style resistor should be counted as one-half the value of the sheet resistance.

Top-hat (lobe type) Configuration: The advantage of a top hat design is its wide trim range. Here we have a five square resistor. By trimming with a single plunge cut of the laser, a nine square resistor can be created. The resistance can be manipulated between these values by limiting the amount of trim. Resistors with a trimmable range of more than 3x the initial value can be created using this technique. Resistors of this type must be trimmed regardless of tolerance requirements.