Drytek2 Model 100, drytek2

The Drytek plasma etchers at SNF all use chlorine and fluorine-based chemistry for etching various Si, polysilicon, nitride, tungsten, tungsten silicide films. Drytek4 (contaminated) also has additional capabilities for oxide etching and argon sputter etching.

Drytek2 Model 100, drytek2

Picture and Location

Background

Process Capabilities

Cleanliness Standard

Performance of the Tool

Special Notes or Restrictions

Contact List and How to Become a User

Contact List

Training to Become a Tool User

Drytek2 Etcher Training Check list

Operating Procedures

General Operating Information

Button Information

Operating Procedure

Quick Start Instructions

Recipes and Etch Rates

Additional Information About Recipes

Process Monitoring and Machine Qualification

Qual Process Overview

Procedure

Reported Data

Qualification Results

Machine Status States

Picture and Location

Drytek2

Drytek2 wafers and electrodes:

Electrodes and Wafers

 

Background

Drytek2 is a plasma etcher for etching nitride, poly, Ti, W, and Si. It is also used for resist hardening O2 descum of patterned resist, and polymer stripping. Drytek2 has six etch electrodes and uses SF6, CHClF2, CF4, and oxygen. See the process and etch rate chart for the processes allowed in this machine. Any process not listed, must be approved by SpecMat.

Features:

Process Capabilities

Cleanliness Standard

 Drytek2 is considered clean, semi-clean and contaminated.  The bottom two of six electrodes have been converted for contaminated work, while the top four are clean/semi-clean.

Performance of the Tool

What the Tool CAN do

What the Tool CANNOT do

Special Notes or Restrictions

Non-metals and standard metals (Al, Ti, and W) are allowed in Drytek2, the top two electrodes. (See the MATERIALS section for material and equipment compatibility).

Contact List and How to Become a User

Contact List

The following people make up the Drytek2 Team:

Training to Become a Tool User

We do not have a staff member assigned to training on it at this time.  What we suggest is that labmembers wanting training on the tool contact a trained research group co-worker or other trained labmember for training and/or shadowing.  Once the 'trainee' is comfortable in the use of the tool they contact the responsible Process Staff member for badger qualification.  This is done with the understanding that the newly trained labmember may be approached for training eventually.

If you cannot find someone to train you after looking at history in badger please contact the responsible Process Staff member and a trainer will be identified.

The labmember is responsible for having read and understood any and all documentation related to the tool. A Training Check List is included in these Operating Instructions. It can be a good tool to make sure everything has been covered in the shadowing session.

Please print and fill out this Shadowing Form. After the session give the form to the responsible staff member for qualification.

 

Drytek2 Etcher Training Check list

This check list represents the basic knowledge of the tool that new users should have. 

General Guidelines

 Before you use Drytek2 please read the new operating instructions located in the blue book and on the wiki.  They contain a new, as of 9/8/2011, RF tuning procedure.  The changes have been underlined or italicized to highlight them. In addition, there is a log form for you to fill out at the end of the etch.  You will be asked for the coil and cap settings.  They can be found by looking on the coil and cap tuning pots (the black knobs used to tune the RF).  We want to collect this information so that users of the tool can refer back to the last settings used for a given recipe and plug them in to ease the RF tuning procedure.

Lastly, we are requiring the labmembers turn the RF power level to zero after using the tool.  This will limit wear and tear on the RF power supply.  We also ask that users tune the RF at a much lower power (40W) before turning the RF to the full power desired.  This procedure is covered in the new operating instructions.

General Operating Information

Pre-treatments:

Post-treatments:

Gas Information:

Gas Switch #

Chemical Symbol

Chemical Name

Maximum Flow

1

CF4

Freon 14

84 sccm

2

SF6

Sulfur Hexafluoride

280 sccm

3

CHCIF2

Freon 22

240 sccm

4

O2

Oxygen

200 sccm

Button Information

MICRO RESET

CYCLE START

CYCLE HOLD

CLEAR WAFER

To end a process before the timer has timed out:

STAND BY

Operating Procedure

Check Standby Conditions:

 Setup and system check:

Always run a test process before loading your wafers. There are two reasons for this. First, you need to set up the matching network so the rf generator does not see excessive reflective power, which will shorten it life. The second reason to “season” the chamber is that seasoning brings the chamber surface chemistry to equilibrium with the process being run so your process stabilizes quickly after the plasma is turned on. Seasoning leads more repeatable etching results.

Etch Procedure:

Shutdown Procedure:

Quick Start Instructions

Quick Start Instructions

Recipes and Etch Rates

Drytek 2 Recipes and Etch Rates

Additional Information About Recipes

Procedure for balancing RF power to electrodes

Drytek 2 - Balancing RF power to electrodes

Process Monitoring and Machine Qualification

Each month, tool qualification runs are performed on most tools in the SNF to monitor variations in each tool’s performance. The purpose of the Drytek2 qual is to monitor poly program trends such as etch rates of poly and photoresist, selectivity of those materials, and wafer-to-wafer and within-a-wafer uniformity of etch. The qual is performed by SUMO members, but users may perform the specified qual process before tool use if more recent qual data is desired for reference.

For more information on the SNF tool performance monitoring system and SUMO, please see the Monthly Tool Monitoring page under the Equipment tab on the SNF wiki.

Qual Process Overview

The Drytek2 qual runs three wafers through the poly-etch program, testing both the gold electrode and the clean electrode. First, two wafers with a 1.6um 3612 Photoresist pattern are etched for two minutes (one on the gold electrode, the other on the clean electrode) to obtain the photoresist etch rate. Then one wafer with 10,000A SiO2 coating is etched on the gold electrode for one minute. Nanospec measurements are taken before and after etching to calculate the PR and SiO2 etch rate respectively. To calculate the Si:PR selectivity, the two wafers coated in photoresist are then stripped of resist so that the Silicon step height may be measured via Alphastep.

Procedure

Wafers for Processing

SUMO Wafer #

(all Si 4" wafers)

Coating

Pattern

(using SUMO mask)

Electrode to be Tested

45

 10,000A SiO2

-

gold

 86

 -

 1.6um 3612 PR pattern, 1min bake @ 110C

clean

 87

 -

 1.6um 3612 PR pattern, 1min bake @ 110C

 gold

 

Pre-Etch Wafer Measurements

All pre-etch measurements are taken on Nanospec. Reference the SUMO Characterization How-To's for Nanospec operating procedure.

For Wafer 45, use the Oxide on Silicon Recipe (#1). For Wafers 86 and 87, use the Positive Resist on Silicon Recipe (#10). Use 10x magnification for all measurements (Objective 1 on Nanospec).

  1.  Use the reference wafer to calibrate before measuring.
  2. Take readings for the Center, Top, Flat, Right and Left positions of the wafer. Readings should be taken about 15mm from the wafer edge.
  3.     a.  For Wafers 86 and 86, measure the PR thickness, which is darker in color than the Si. Accidentally measuring the Si will result in a <100A reading.
  4. Calculate the average.
  5. Record results on the SUMO Qualification Log Sheet.

Etch Process

Before loading the wafers,  season the chamber so that the chamber surface chemistry is brought to equilibrium with the process being run. This enables the actual process to stabilize quickly after the plasma is turned on. This seasoning also leads to more repeatable etching result.

  1. Season the chamber for 10 minutes using the poly etch program (Process 2).  Follow the standard operating procedure as outlined above, or on the procedure print out at the tool. Be sure to check the program parameters while seasoning and adjust the resistor/capacitor settings as necessary.
  2. For Wafers 86 and 87 (1.6um 3612 PR pattern), set the etch time for 2 minutes.

             a.  Remember to bake the wafers at 110C for 1 min before the etch.

             b.  Run the poly-etch recipe.

             c.  Monitor gas flow rate, RF power, and reverse power.

   3.   For Wafer 45 (10,000A SiO2), set the etch time for 1 minute.

             a.   Run the poly-etch recipe.

             b.   Monitor gas flow rate, RF power, and reverse power.

   4.    Record process settings on the Drytek2 process log.

 

Post-Etch Wafer Measurements

  1. Measure post-etch thickness for all wafers using the same Nanospec as before and the same respective Nanospec analysis recipes.
  2. Take readings for the Center, Top, Flat, Right and Left positions of the wafer. Readings should be taken about 15mm from the wafer edge.
  3. Calculate the etch-rate for PR and SiO2 by subtracting the post-etch thickness from the pre-etch thickness and then dividing by etch time.
  4. To calculate selectivity, measure the Silicon step height of wafers 86 and 87.
  1. Strip the wafers of PR using the Strip.rcp recipe on Matrix. A 2 minute (120sec) run should be sufficient.
  2. Measure the step height at each of the 5 points via Alphastep. Readings should be taken about 15mm from the wafer edge.
  3. Calculate the average step height.
  4. Calculate the amount of Si lost and divide by etch time to determine the Si etch rate.
  1.  Calculate the selectivities by dividing the PR etch rate by the Si etch rate for the Clean chamber and Gold chamber, and then the SiO2 etch rate by the Si etch rate for the Gold chamber.

 

Reported Data

Qual data may also be found on the Badger comment log. The following data is reported for the Drytek2 qual:

Clean Chamber

Gold Chamber

Qualification Results

   

Machine Status States

 For older process qualification results click Old proces qual data