KLayout NMOS Array Generation

This script automates the generation of NMOS transistor arrays in KLayout for testing diffusion-to-diffusion spacing variation. It instantiates a grid of NMOS devices with systematically varied horizontal spacing between cells, enabling process characterization of contact formation across different diffusion separations.

How It Works

The script places a 4-row × 5-column array of NMOS devices by calling the existing NMosfet PCell from the design library. Each row contains 5 instances with increasing diffusion-to-diffusion spacing: 2, 4, 6, 8, 10 µm.

For each device instance, contact holes are automatically inserted into both the source and drain diffusion regions. Contacts are placed at fixed local offsets (±4.5 µm from the center) and tiled along the channel width direction at a pitch of 2 µm.

Device parameters used:

Parameter	Value
Channel Length (L)	5 µm
Channel Width (W)	50 µm
Diffusion Length	40 µm
Contact size	0.4 µm × 0.4 µm
Contact pitch (along W)	2 µm
Row spacing (Y)	100 µm

Usage

1. Open KLayout and load your layout with the NMOSFET PCell library loaded

2. Open the Ruby macro editor (Macros → Macro Development)

3. Paste the script — Array.lym

4. Modify the spacing parameters at the top of the script to suit your experiment:

all_spacings = [ [2.0, 4.0, 6.0, 8.0, 10.0], # Row 0 [2.0, 4.0, 6.0, 8.0, 10.0], # Row 1 [2.0, 4.0, 6.0, 8.0, 10.0], # Row 2 [2.0, 4.0, 6.0, 8.0, 10.0], # Row 3 ]

1. Run the script. The layout will be cleared and regenerated as CONTACT_MASK_DESIGN

Output

The script produces a single top cell named CONTACT_MASK_DESIGN containing the full array. The view automatically fits to the generated layout upon completion.

Limitations

• Contact positions are hardcoded relative to the cell center and may need adjustment if the PCell geometry changes.