ECE/ChBE 4752 SUPREM Simulation Guide

Fall 2010

Discussion Topics

• What is SUPREM?• Location of Computers with SUPREM• Using SUPREM Oxidation Example we will discuss:

– Starting SUPREM– Running SURPEM simulation– Viewing and Modifying Graphs (TONYPLOT)– Viewing Output window

• Netlist Structure of SSUPREM3– Headings/Comments– Initialize– Diffusion– Etch– TonyPlot

What is SUPREM

• A universal 1-D process simulator

• Allow to simulate the various process steps – Diffusion– Oxidation – Implantation– Epitaxial growth– Deposition or etching

Computer Labs for SUPREM

• Klaus building room 1440.– http://gtalumni.org/map/index.php?id=153– Accessible to all students enrolled in one of

ECE or ECE cross linked course.

• User ID/ Password– GT account

Starting SUPREM

To start SUPREM, click on:

“Start>Programs>Silvaco”

Starting SUPREM

Next, double click on the “Deckbuild” icon“Deckbuild” is Interactive Deck Development and Runtime environment.

Starting SUPREM

This will open a blank file. Click “File>Open” to open the netlist that will be simulated

Starting SUPREM

Once you have chosen the file, click OK and the file contents will appear.

(Note: This is notthe only way to opena file. If you savea text file with a “.in”extension, doubleclicking on that filewill cause deckbuildto open it as well).

Running SUPREM Simulation

To simulate the netlist, click on the green arrow (“Run”) as shownbelow:

Running SUPREM Simulation

Once the simulation is complete, a plot of the simulation data will be available(TONYPLOT)

TONYPLOT Graphs

To change the labels (x label, y label, title) on a TONYPLOT graph, click on“Plot>Annotation” from the Tonlyplot window:

TONYPLOT Graphs

From the Annotation window, theX, Y, and Titles can be changed

TONYPLOT Graphs

The final graph will look like:

Saving TONYPLOT Graphs

To save the Tonyplot graph click on “File>Save As” and chose the desired file format (.jpg, .bmp, etc.).

Saving Output Window

Sometimes it is very difficult to read from the graph exact values that you are interested in. The output file can provide a more accurate result than an estimation from the output graph. To view the output file, first save it by clicking on “File>Save Output Window” from the Deckbuild window:

Saving Output Window

Choose the name and location of the file. The file will be given a .txt extension

Opening Output Window

To open the output window, select it by clicking on it once. Then click theright mouse button and select “Open With>WordPad”.

Viewing Output Window

The output window provides the results from the simulation.

Diffusion Example

The graph below provides the Tonyplot for a diffusion problem

Diffusion Example

The output file from this diffusion simulation can tell us exactly where the junction depth is for this example:

Junction Depths and Integrated Dopant Concentrations for Each Diffused Region layer region type junction depth net act total chem no. no. (microns) Qd (1/cm^2) Qd (1/cm^2) 1 2 p 0.0000 3.4687E+13 3.5123E+13 1 1 n 6.6202 3.2902E+11 3.6783E+11

Understanding SUPREM netlist

go ssuprem3

TITLE Oxidation ExampleCOMMENT Initialize silicon substrateINITIALIZE <100> Silicon Phosphor Concentration=1e16COMMENT Ramp furnace up to 1100 C over 10 minutes in N2DIFFUSION Time=10 Temperature=900 Nitrogen T.rate=20COMMENT Oxidize the wafers for 5 minutes at 1100 C in dry O2DIFFUSION Time=5 Temperature=1100 DryO2COMMENT Oxidize the wafers for 120 minutes at 1100 C in wet O2DIFFUSION Time=120 Temperature=1100 WetO2COMMENT Oxidize the wafers for 5 minutes at 1000 C in dry O2DIFFUSION Time=5 Temperature=1100 DryO2COMMENT Ramp furnace down to 900 C over 10 minutes in N2DIFFUSION Time=10 Temperature=1100 Nitrogen T.rate=-20

PRINT Layers Chemical Concentration PhosphorTONYPLOTSTOP End oxidation example

Below is a simple SUPREM netlist that grows an oxide layer on topof the Silicon Substrate. The next slides will explain the SUPREM syntaxrequired to perform process steps such as diffusion, oxidation, etc.

Netlist Structure (Heading, Title, Comments)

• Always include the “go ssuprem3” command line at the beginning of the simulation code.

• The TITLE Command is used to provide a title to the current simulation.

• The COMMENT Command allows for use of comments for code clarification.

go ssuprem3

TITLE Lab 6 Diffusion Simulation (Find P-well depth)COMMENT Initialize silicon substrate

Sample Code:

Notes:

Netlist Structure (Initialize Statement)

• The Initialize statement sets up the initial structure and the parameters that will be used in the process.

• The “Thick” parameter tells the simulator how deep the simulation is (how thick the wafer is). By default, Thick = 2 μm. You may need to change this option for diffusion simulation.

• For this particular example, there is a (1 0 0) Silicon wafer with an initial Phosphorus concentration of 5 x 1014 and a thickness of 8 um.

Initialize <100> Silicon Phosphor Concentration=5e14 Thick = 8

Sample Code:

Notes:

Netlist Structure (Diffusion Statement)

• Increasing the temperature of the furnace.

• Creating an oxidation layer using wet oxidation process.

• Creating an oxidation layer using dry oxidation process.

• Diffusing dopant into wafer (Pre-depth process)

• Diffusing dopant deeper into wafer (Drive-in process)

The Diffusion Statement has many different purposes in the SUPREMsimulations performed for this class including:

Netlist Structure (Diffusion Statement)

• This diffusion statement will increase the temperature of the furnace to a final temperature of 1100oC, beginning at a temperature of 900oC

• The rate of temperature increase is 20oC/min (this number can be negative to indicate a decrease in temperature.

• The total time the increase in temperature rises is 10 minutes.

• The ambient gas in the furnace is Nitrogen. (Thus no oxide layer can be grown during the ramping process)

COMMENT Ramp furnace up to 1100 C over 10 minutes in N2DIFFUSION Time=10 Temperature=900 Nitrogen T.rate=20

Sample Code:

Increasing the temperature of the furnace.

Notes:

Netlist Structure (Diffusion Statement)

• This diffusion statement will perform a wet oxidation process for 60 minutes at a temperature of 1100oC.

COMMENT Oxidize the wafers for 60 minutes at 1100 C in wet O2DIFFUSION Time=60 Temperature=1100 WetO2

Sample Code:

Creating an oxidation layer using wet oxidation process.

Notes:

Netlist Structure (Diffusion Statement)

• This diffusion statement will perform a dry oxidation process for 5 minutes at a temperature of 1100oC.

COMMENT Oxidize the wafers for 5 minutes at 1000 C in dry O2DIFFUSION Time=5 Temperature=1100 DryO2

Sample Code:

Creating an oxidation layer using dry oxidation process.

Notes:

Netlist Structure (Diffusion Statement)

• This diffusion statement will perform a pre-depth diffusion process, using Boron, at 900oC for 25 minutes.

•The “Solidsol” statement will set the concentration of the specified impurity (Boron in this example) in the ambient gas at the surface of the wafer to the default solid solubility of the impurity in silicon.

•The structure statement (outfile=) will save the results in tonyplot format. (Save multiple files for different processes, if desired).

Sample Code:

Diffusing dopant into wafer (Pre-deposition process)

Notes:

COMMENT P-well pre-depDIFFUSION Time = 25 Temperature = 900 Boron Solidsolprint Layers Active Concentration Phosphor Boron Netstructure outfile=time100.str

Netlist Structure (Diffusion Statement)

Layers – indicates that specific information about layers (such as junction depth, layer thickness, etc.) will be included in the output file.

Active – indicates that the electrically active impurity concentrations will be include in the output file.

Concentration Phosphor Boron Net – indicates that the concentration of Boron, Phosphorus, and the Net versus depth will be included in the output file.

Sample Code:

Print Statement

Notes:

print Layers Active Concentration Phosphor Boron Net

Netlist Structure (Diffusion Statement)

• This diffusion statement will perform a drive in diffusion process, using Nitrogen as the inert ambient gas, at a temperature of at 1175oC for 350 minutes.

•Notice, the difference between the pre-depth step and the drive in step is “Solidsol” being replaced with “Nitrogen”.

Sample Code:

Diffusing dopant deeper into wafer (Drive-in process)

Notes:

COMMENT P-well Drive in Diffusion Time = 350 Temperature = 1175 Nitrogenprint Layers Active Concentration Phosphor Boron Netstructure outfile=time200.str

Netlist Structure (Etch all Oxide)

• The ETCH command can be used to remove a particular material from the substrate. The above statement can be used to etch away all oxide.

ETCH Oxide all

Sample Code:

Notes:

Netlist Structure (TONYPLOT and STOP)

• The TONYPLOT command will start the tonyplot program that is used to view simulation results.

•The STOP command will indicate to the simulator where to end the simulation.

TONYPLOTSTOP End oxidation example

Sample Code:

Notes:

Netlist Structure ( additional syntax information)

• SUPREM is not case sensitive (DIFFUSION = diffusion)

• Line continuation is preformed with the “\” character.

• Create and/or modify netlist with any text editor program, but save with “.in” extension. This way you can write net lists at any computer before simulating them in SUPREM.

SUPREM Commands

Title/Comment None None

Initialize antimony/arsenic/boron/phosphorus

Silicon

<100>/<110>/<111>

concentration (cm^-3)

spaces (#) – number of spaces to be used in the calculation

thickness (um)

dx (um)-grid spacing at xdx

xdx (um)-distance from the top of the first layer at which the grid spacing is dx

Diffusion antimony/arsenic/boron/phosphorus

dryO2/nitrogen/wetO2

Solidsol-sets surface conc to solid solubility

HCl% (%)

pressure (atm)

temp (Celsius)

time (min)

Print Active/chemical/all/total/net

antimony/arsenic/boron/phosphorus layers

Xmin (um)

Ymin (um)