STS Deep RIE Etcher, stsetch

This is a IPC (Inductive Charged Plasma) Deep Reactive Ion etcher from Surface Technology Systems. The platform is single-chamber, manual loadlock system. The etch process is based on the patented Laermer and Schlip process, commonly referred to as the Bosch Process. The etch process alternates between the passivating C4F8 plasma and the silicon etching SF6 plasma.

STS Deep RIE Etcher, stsetch

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Background

What the tool is and is not

A brief description of the machine chuck and clamp

Stsetch Frequently Asked Questions

Contact List and How to Become a User

Operating Instructions

Description of Software and Definition of Action Buttons

Stand By Conditions

Load and Edit a Program

Starting an Etch

At the Completion of the Etch

The Paperwork

More on Recipes

Training Checklist

Quick Start Instructions:

Process Characterization Data

Process Monitoring and Machine Qualification

Purpose

Frequency

Qual Process Overview

Procedure

Process

Reported Data

Qualification Results

Recipe Conditions

Machine Status States

Process Modules

Preparing Wafers for Through Etching

Picture

 

STS Deep RIE Etcher

Background

The following information is provided to SNF labmembers as an aid in making the decision to use or get training on the STS RIE tool. The information provided here is the result of several years of working with the tool and encountering many different types of inquiries about the machine. It is also based on the mistakes of past users of the tool.

 What the tool is and is not

Whether to use the STS etcher or not is based on what the final structure will be. Just because it etches Si very quickly does not mean it is the best tool for the desired outcome. For example; it is not an alternative to CMP, it is not a wafer scriber, nor is it a resist asher. It may not be the best choice for trench work either; users wanting to put electrically active devices near the trench should look into using another method of etching.

It is not a finesse machine. The Bosch process etches though Si leaving scalloped sidewalls. Some structures may exhibit a swirling etch pattern at the inside corners of the device. The bottom surface of the etched area is not smooth. Larger areas etch faster than smaller ones. And very large open areas of Si may show grass or micromasking.

Although the ideal amount of exposed Si is about 20% (evenly distributed) for the standard programs, any questions about mask layout should be directed to staff. There are some designs which will guarantee the wafer will not survive the etching.

A brief description of the machine chuck and clamp

The SNF STS machine uses a mechanical clamp to hold the wafer to a chuck. This clamp is made up of eight ceramic 'fingers' which bear down near the edge of the wafer to hold it onto the chuck. The chuck provides He backside cooling to the wafers. This keeps the wafer cool enough during the plasma process so that the resist does not etch very quickly (selectivity to Si is about 75:1) and also minimizes resist burning.

The wafer to chuck interface is aided by a lipseal (like an o-ring), which stops the He from leaking into the chamber and changing the etch rate. The backsides of the wafers must be clean of resist, debris, tape or any other material which would break the seal. It is best to think of this seal as being similar to a vacuum seal.

Additionally, the wafer must free of resist developer. As with all the etchers in the facility, the STS chuck may be corroded by the developer. To avoid damage to the chuck all wafers should go through a full six-cycle rinse after development and be inspected before placing into the etcher.

Helium is delivered to the bottom of the wafer at about 10 torr of pressure. Coupled with the downward pressure of the clamp fingers, it is easy to see that the wafer is subjected to a large amount of force. This force must be kept in mind when etching, for as the etch goes deeper, the wafer gets weaker. In many cases wafers with 400µm of remaining Si thickness have broken in the chamber. We therefore require that for etches that will leave less than 400µm of Si remaining on the process wafer be bonded (using photoresist) to a support or carrier wafer using the procedure as outlined in the following link; stsetch/stsprep .Wafers must be bonded and not simply placed over another wafer. The bonding aids in thermal transfer enough to keep the resist from burning.

This obviously includes wafers with a starting substrate thickness of less that 400µm. Support wafers should be the standard 500-550µm thick.

Exceptions to these policies are decided on a case-by-case basis by responsible staff members. Labmembers must consult with staff and not assume that another labmember's process is the same as theirs.

Final comments on STS Etcher Use

It should be noted that the STS etcher is one of, if not the, most heavily used pieces of equipment in the lab. Any labmember trying to make a reservation on the machine will attest to that fact. Accordingly, any downtime on the machine affects subsequent users and can set back timetables or cause the loss of hard fought for reservations.

A user should use the machine shutdown option if a wafer is broken in the chamber, even if the broken piece is not on or around the lipseal. As pieces continue to etch they may become light enough to be sucked into the vacuum system.

A shutdown should be initiated if the turbo pump fails or the software freezes. In addition to alerting the maintenance personnel, the shutdown informs off-site labmembers there is a problem which may affect their reservation.

Obviously, if a labmember observes the etcher is operating in an unsafe fashion they should shut it down. Any deviance from the norm of 1) chamber pressure, 2) gas flow, 3) He pressure or flow or 4) RF conditions should be reported to staff via the machine problem option.

If there are any questions regarding layout design, previous processing steps completed before etching, machine capabilities, resist bonding issues, Si etching issues or general machine issues, please consult SNF staff.

 Stsetch Frequently Asked Questions

Deep etching refers to long etches, typically >60 mins, which attempt to etch a significant fraction of the wafer thickness (>1/4). For standard 400-500um thick wafers, this addresses etch depths >100um. Key issues include;

  1. wafer structural integrity
  2. etch rate and uniformity.
  3. mask selectivity etch rate and uniformity.

Imagine the wafer when the etch is complete. Can it withstand a force caused by 10 torr backside pressure and 30 mtorr frontside? Can it withstand the pressure of the mechanical clamp fingers on its edges? Are there any small chips which could come loose? Any scribe lanes which might form a cleave plane?

Mask design considerations should include the number and size of the features to be etched and their proximity to the edge of the wafer.

A good rule of thumb is to etch no deeper than 100um without the special holder. Using the holder and guard ring greatly reduces the chances that the wafer will break in the chamber requiring about a full day's shutdown of the etcher for removal and cleaning of the chamber.

The etch rate of Si depends on a few things; feature size (larger features etch faster than smaller ones), the amount of Si that is exposed (10% or less exposed Si for a given mask slows things down, but the etch is more uniform across the wafer) and the etch recipe used. Typical recipes are :

Recipe Name

Etch Rate Range

Comments

DEEP

1.8-4 um/min

Std Bosch process

FASTDEEP

Up to 5 um/in

Sidewalls not smooth

SMOOSHAL

0.5-2 um/min

For depths of 5-20 um-micromasking (grass) may occur at longer etches

SMOODEEP

1.8-4 um/min

For smoother sidewalls

The selectivity of oxide to Si is about 100:1, depending on structures being etched.

The selectivity of nitride to Si is about 75-125:1.

Photoresist etches at about 250A-600A/min, depending on post-exposure treatment. Thick resist (7um or more) is recommended for etches lasting more that 30 mins.

Photoresist, oxide and nitride are the most commonly used etch masks. Others, such as polyimide tape (kapton), are used with staff approval of process and material compatibility.

Standard SNF metals (Al, Al/Si, Ti, and W) may be used as etch stops, but not etch masks. Ideally, metal is covered in photoresist or oxide.

For etches lasting more that 30 mins or about 100um deep, SPR220-7 must be used in a thickness of 7um, 10um or 18um. Please consult the SPR220-7 page in the Photolithography section of the Process Library. Extra hotplate bakes may be required.

For all thicknesses of SPR220-7 a post exposure bake is needed. Using the ovens a bake of 110C for 30 mins or 90C for 45-60 mins. This bake is needed to harden the resist to the long etches. The choice of higher temp is based on whether the user can tolerate reflow or misshapen enlargement of the device features. For larger features (50um or more) this is probably not an issue.

Resist thickness of 10um of SPR220-7 , when baked properly should be able to withstand about 5 hrs of etching using the DEEP recipe.

When etching through a wafer it is highly recommended for most cases to bond the device wafer to a blank support wafer. A user would choose not to use a support wafer if the device wafer had underlying etch stop material layers sufficient to a) structurally support the wafer, and/or b) not be completely etched away exposing the chuck to the plasma. This is somewhat risky and staff should be consult if there is any question.

The procedure for mounting a wafer to a support wafer follows:

The aluminum holder and guard ring were developed to address issues of wafer structural integrity and machine chuck protection. The holder and guard ring are used in place of mounting device wafers to a support wafer. The holder and guard ring have the following features:

a) A .A. Ayon, R. Braff, C.C. Lin, H.H. Sawin and M.A. Schmidt, J. Electrochem. Soc., 146, 339 (1999).

Contact List and How to Become a User

Training

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.

Operating Instructions

 Basic System and Process Description 

The STS is an ICP (Inductively Charged Plasma) etch system which uses the ‘Bosch’ process to etch deeply into silicon or polysilicon.  During the etching process gases toggle in user set cycles of SF6 (to etch anisotropically) and C4F8 (to deposit a sidewall protecting polymer or passivate the wafer surface).

A description of the tool may be found in the section “A brief Description of the machine chuck and clamp”

Labmembers requesting training on stsetch must be familiar with this information.

Labmembers should also have read over the following Frequently Asked Questions prior to hands-on training with a staff member:

Description of Software and Definition of Action Buttons 

The software displays four windows in normal run mode; two informational schematic windows (ICP and Machine View) and two task windows (Transfer and Process Control-ICP).  Let’s go over each of the windows;

ICP View; this window show the requested and actual set points for gas flow, RF power and matching values while to system is etching a wafer.

Machine View; this window displays the wafer status, load-lock and chamber pressure.

Transfer; this window is where the users requests via buttons that a wafer be loaded, unloaded, the load-lock be vented, or the loading process be aborted.  There is also a close button which will close the window altogether.  To restore the window after an accidental close go to the toolbar and look for the window in either Control Panel or Window.

Process Control-ICP; this is the window where the users loads, edits or creates a recipe and controls the actual etch process.  These are the buttons and there functions;

Stand By Conditions

  1. Verify the turbo pump is on by checking the electronics rack located behind the pump.  The third panel from the top marked Pfeiffer Vacuum has a digital read out window.  It should read 390-400Hz.  If it drops below 390, please report it as a problem.
  2. Look around the loading deck for any notes.  There may be a message asking the next user of the tool remove a wafer from the chamber.  A proper storage container should be available for the wafer.
  3. The load-lock should be left vented.

Load and Edit a Program  

1) After enabling stsetch, click on the aqua colored recipe name found on the far left-hand side of the Process-ICP window.  This will open the file that contains all the recipes.  Search the file until you find the desired recipe.  Be careful; many recipes have very similar names.  Be sure to choose the correct one.

► This loads the recipe.

2) Click on ‘Recipe’ on the right-hand side of the Process-ICP window.  This will bring up the chosen recipe.

3) The file should open on the page containing the Standby Step parameters.  This step is run automatically before and after the etching step.  Most recipes have this step set to these values;

Standby Gas-ARGON

Flow Rate               0sccm                             (Ar is not even plumbed to the tool)

Pumpdown Time  00:00:20

Purge Time               00:00:10

Pump Out Time        00:00:30

Base Pressure   4mT

Pressure Trip   94mT                                 (The pressure operating range)

4) Click on the recipe name on the left-hand side and then on the tab labeled General to get to these input fields;

Pumpdown Time   00:00:30

Gas Stabilization   00:00:10  

Process Time            (variable)                     (User defined time)

Pump Out Time         00:00:30

Parameter Switching             (The box must be checked for the Bosch process)

○ Etch First

○ Pass First                               (User chooses whether to etch or passivation first)

Etch Time

Pass Time

Overrun                           (This is where both gases, SF6 and C4F8 are on at the same time)

5) Click on Pressure to get to the pressure page.  APC (automatic Pressure Control) is set to manual.  It’s a long story, but we lost the ability to use APC when the turbo pump was upgraded.  The APC setting is a percentage of how open the valve is.  A one percent change is significant.

Base Pressure         1mT                 (This is a change from the Standby page)

Pressure Trip        94mT

6) Click on the Gases to get to the gases page

 SF6   Flow   Tol%          (Tolerance should be set to around 20% to avoid an error)

C4F8 Flow   Tol%

7) Click on RF to get this page.  There are two generator sources, Coil and Platen (chuck). The coil generator is on for both the etch and passivation steps, but the platen generator is on only during the etch step.  This gives directionality to the plasma and creates approximately 90° sidewalls.

Platen Generator

                                Etch                         Passivate

Power              (Typical value is about 120W.  This is actually only 12W as there 10X scale)

Tolerance

Coil Generator

                                Etch                         Passivate

Power               (Typical value is 600W.  The 10X scale is off)

Tolerance

In both cases the matching should be chosen and the Load and Tune set to 50%.

8) Click Endpoint to get to the endpoint page.  We do not have an endpoint detector on the system, so the disabled box is checked.

► This completes the review of a recipe.

NOTE: We strongly encourage to user to check his/her recipe before every use.  Any user can change any parameter of any recipe at any time.  Please protect your work by verifying the recipe is correct.

If you change a parameter of a recipe, for example Time, please use the EXIT option on the toolbar to exit.  As you do this you will be asked if you want to saves changes.  Answer yes.  You will then be shown the file you are about to change.  Answer yes.  You will be prompted that the file exists and asked if you want to over write it.  Answer yes.

We also encourage users to condition the chamber by running 10-15 mins of the desired recipe.  Additionally users may want to run the O2CLEAN recipe for 20 mins prior to the conditioning run to strip polymer in the chamber.  This may be important to users concerned with grass (micromasking) formation.

►This completes the editing of a recipe.  For more information about recipes, please refer to the More on Recipes section of these instructions.

Starting an Etch

At the Completion of the Etch

The Paperwork

Users of the tool are asked to fill out the log form located in the binder near the tool.  You will be asked for the following information;

Date, login ID and Recipe used.

He Flow (after wafer loads) and He Flow (after plasma starts)- these are two checks of the He backside cooling system.   He flow should be between 3.7-4.0 Sccm.  There will be a diffenece from no wafer to a wafer loaded and no plasma to a wafer with the plasma on.  Recording this gives us a check of how the He cooling system doing.

The other thing that is being checked here is that those numbers are steady and not fluctuating.  If they are, there is a He leak.  This means the He is escaping and your wafer is getting hot, you lost control of the etch and it is no longer anisotropic.

To fix this problem do the following;

You may have to do this procedure more that once.  Examine the wafer carefully; there may be small cracks or you may have punched through a feature.

Chamber Pressure Passivation/Etch- you are asked to note the chamber pressure during the etching as a check status of the vacuum system.  This can be an indicator that the lines are beginning to constrict and needs attention.

Wafer #’s- in order to look at the log of the etching run we will need to have the wafer number.  There is no time/date stamp.  The number is located in the transfer window.

Comments- this is the place to note comments during the etch.  Obviously, equipment problems should be noted in the computer system.

More on Recipes 

There are four staff maintained recipes; DEEP, SMOODEEP, SMOOSHAL, FASTDEEP and O2CLEAN.  This means that users are welcome to use these recipes, but if any parameter is changed besides Time, the user is requested to write their own recipe.

 Here are the four recipes with a basic explanation of why they were created and when a user might want to use them; 

Recipe Name

Etch

Passivation

DEEP

SF6 Flow- 130 sccm

C4F8 Flow- 85 sccm

 

RF Coil- 600W

RF Coil- 600W

 

RF Platen- 120W

RF Platen-0W

 

Time- 12 secs

Time- 7 secs

This is a basic Bosch process recipe.  It has been the starting point for many users who have gone on to customize and write their own recipes.  The etch rate is very much dependant on the size of the features to be etched and the amount of wafers surface that is exposed silicon.  Recent testing using patterns with about 15-20% exposed silicon has the etch rate at about 1.8-2.0µ/min.  

Users are very strongly encouraged to establish the etch rate of critical features for each patterns (mask level) etched. 

Recipe Name

Etch

Passivation

SMOODEEP

SF6 Flow- 130 sccm

C4F8 Flow- 85 sccm

 

RF Coil- 600W

RF Coil- 600W

 

RF Platen- 120W

RF Platen- 0W

 

Time- 9 secs

Time- 7 secs

This recipe was developed in an effort to smooth out the ‘scalloped’ side walls when using the DEEP recipe.  In DEEP there are roughly 10 scallops per micron of etch depth.  SMOODEEP has a faster gas toggle rate and hence there are more scallops per micron. 

Recipe Name

Etch

Passivation

SMOOSHAL

SF6 Flow- 130 sccm

C4F8 Flow- 120 sccm

 

RF Coil- 600W

RF Coil- 600W

 

RF Platen- 120W

RF Platen- 0W

 

Time- 6 secs

Time- 5 secs

SMOOSHAL is a recipe to be used for etch depths of less than 20µ.  Micromasking (grass) may occur at deeper etch depths.

Recipe Name

Etch

 

O2CLEAN

O2 Flow- 40 sccm

 

 

RF Coil- 600W

 

 

RF Platen- 80W

 

 

Time- 30 mins

 

 

O2CLEAN is a recipe that is used primarily after the chamber has been exposed to air, say, after a broken wafer has been cleaned up.  Users are encouraged to use it before critical etches, but need to be advised to also run the desired etch program for 10-15 mins after O2CLEAN to condition or season the chamber.  The clean is also done before running the process quals.

Training Checklist

£ Be familiar with basic equipment and Bosch process description.

£ Be aware of the proper use of the mechanical clamp and its’ limitations.

£ Have read the general information and FAQs.

£ Know the machine stand-by conditions.

£ Know the four windows of the software and the functions of action buttons in the task windows.

£ Demonstrate correct loading and editing of recipes.

£ Know how to position and load a wafer into the process chamber.

£ Know how to start a recipe and how to stop the process before completion.

£ Know when to use the holder vs using a carrier wafer.

£ Know what faults should be recorded as a problem or a shutdown.

£ Demonstrate properly filling out the log sheet.

Quick Start Instructions:

Quick Start Instructions

Process Characterization Data

Process Characterization

Process Monitoring and Machine Qualification

Purpose

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 stsetch qual is to monitor Si, PR, and SiO2 etch rates, selectivity of those materials, 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.

Frequency

Quals are run monthly by SUMO. The SUMO member in charge of the tool is Gabriela Lomeli (glomeli4@stanford.edu).

Quals are also run by labmembers periodically, especially under the following circumstances:

After major repairs to the system.

When a labmember reports a variance from normal results.

Qual Process Overview

The stsetch qual runs two wafers through a 2 minute process of the DEEP program - one wafer with a 1.6um 3612 Photoresist pattern, and one wafer with 1,000A SiO2 coating. Nanospec measurements are taken before and after etching to calculate the PR and SiO2 etch rate. To calculate Si etch rate and selectivities, the wafer coated in photoresist is 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)

9

 1,000A SiO2

-

73

 -

 1.6um 3612 PR pattern, 1-2 min bake @ 110C

 

Process

Use 1 blank Si wafer with 1.6um layer of SPR3612 photoresist with 5 mm EBR and 120sec post bake and 1 wafer with 1,000A SiO2, unpatterned. The Si wafer is patterned with the SUMO MASK 2.0.

  1. Measure photoresist thickness using nanospec.  Be sure to use the reference wafer before testing to calibrate the tool.  Take readings for the Top, Flat, Center, Left, and Right positions of the wafer.  Readings should be taken about 20mm from the edge. Record.
  2. Season the chamber for 10 minutes using the DEEP Recipe (00:10:00), running with a blank Si wafer. Be sure to check the program parameters before starting. Monitor gas flows, RF power and chamber pressure during passivation and etch.  Record on Process Qualification Log Form.
  3. Etch the wafer for 2 minutes. Again, monitor gas flows, RF power and chamber pressure during passivation and etch.  Record on Process Qualification Log Form.
  4. Measure post-etch thickness using the same nanospec.  Be sure to use the reference wafer before testing to calibrate the tool. Again, take readings for the Top, Flat, Center, Left, and Right positions of the wafer. Readings should be taken in more-or-less identical spots as the pre-etch measurements.  Record.
  5. Subtract the mean values of the pre-etch measurements from the post-etch measurements.  This gives you the amount of photoresist etched. Record, and take average.
  6. Strip the Si wafer of photoresist via matrix.
  7. Measure the depth of the etch on the Si wafer using alphastep. Find a place that has been etched and measure across it. Make sure to LEVEL if the trace is not horizontal.
  8. Take readings in about the same 5 places as you took readings for the photoresist. Once you get consistent readings in each spot, record the measurement (alphastep cannot save or print data).
  9. Record results. Record results in data file to get within-a-wafer uniformity.

 

Recommendation to users with critical processes

It would be wise to run the qual before committing valuable samples to the deposition.

Reported Data

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

 

Date

Si Etch Rate

PR Etch Rate

SI : PR Selectivity

Comments

12/07/2005

3.36um/min

-

-

Before annual PM

01/03/2006

3.11um

-

-

After annual PM

04/21/2006

2.18um

285A/min

 76 : 1

New resolution mask used- Opposite polarity as before (20% exposed Si)

05/10/2006

 2.45um

 257A

 95 : 1

 

 06/01/2006

 1.7um

 268A

 63 : 1

 

 09/19/2006

 2.18um

 -

 -

 Nanospecs down- unable to measure PR

 11/17/2006

 2.37um

 269A

 88 : 1

 

 12/06/2006

 2.30um

 269A

 85 : 1

 

 01/03/2007

 -

 251A

 -

 Opps- wafers etched again before Si measured

 02/02/2007

 -

 266A

 -

 Double opps- did it again...

 05/22/07

 2.9um

 216A

125 : 1

 Test after C4F8 change out

 07/05/2007

 2.6um

 199A

 130 : 1

 After pump package change

 08/21/2007

 2.49um

 232A

 107 : 1

 Test after C4F8 change out.  Used Zygo for Si measurement

 10/10/2007

2.4um

 230A

 104 : 1

 Zygo

 11/01/2007

 2.8um

 212A

 127 : 1

 Zygo

 01/03/2008

 2.43um

 216A

 123 : 1

 After PM- Zygo

 02/14/2008

 2.37um

 203A

 117 : 1

 Zygo

 03/04/2008

 2.54um

 207A

 123 : 1

 After C4F8 mfc's replaced- Zygo

 05/06/2008

 2.80um

 201A

 139 : 1

 Zygo

 07/15/2008

 2.40um

 226A

 106 : 1

 Zygo

 09/23/2008

 2.69um

 235A

 115 : 1

 Zygo

 11/18/2008

 1.88um

 248A

 76 : 1

 After turbo pump replacement

 1/27/2009

 -

 246A

 -

 

 5/20/2009

 1.6um

 254A

 65 : 1

 Before SF6 calibration (old 130 sccm setting, actual +65% (214 sccm))

 5/20/2009

 1.5um

 239A

 64 : 1

 Before calibration (set to actual 130 sccm, 45 sccm)

 6/2/2009

 2.0um

 233A

 86 : 1

 Re-test after SF6 calibration, 213 sccm ('old' 130 sccm)

 6/2/2009

 1.9um

 270A

 70 : 1

 Re-test after SF6 calibration, 310 sccm (actual!)

 8/11/2009

 -

 234A

 

 Ck after wafer slice removed

 8/12/2009

 -

 234A

 -

 Oxide etch ck- 72A/min, sel = 3 : 1, ox : pr

 9/1/2009

 2.12um

 296A

 72 : 1

 Wafer #1- ck before chamber clean and PM

 9/1/2009

 1.91um

 245A

 80 : 1

 Wafer #2- ck before chamber clean and PM

 9/2/2009

 1.97um

 293A

 67 : 1

  Wafer #1- ck after chamber clean and PM

 9/2/2009

 2.21um

 323A

 68 : 1

  Wafer #2- ck after chamber clean and PM

 12/11/09

2.75um

 254A

 108 : 1

 Before annual shutdown 2009

 1/5/10

 2.41um

 262A

 92 : 1

 After annual shutdown

 2/23/10

 2.25um

 228A

 98.1 : 1

 After He valve repair

 3/23/10

 1.81um

 245A

 73.9 : 1

 

 3/23/10

 2.02um

 206A

 98.1 : 1

 Used holder- reports of slower ER's

 4/2/10

 1.81um

 211A

 85.8 : 1

 Check after chuck rebuild

 4/2/10

 2.09um

 198A

 105.6 : 1

 Check after chuck rebuild- Used holder

 4/30/10

 2.41um

 238A

 101 : 1

 Routine ER check

 5/27/10

 1.71um

 185A

 92 : 1

 Low etch rates reported- He flow and pressure off

 6/8/10

 2.02um

 212A

 95.3 : 1

 After field service visit.  Spring loaded 'pips' removed from lip seal.  Will be replaced by less stiff springs.

 6/15/10

 1.97um

 208A

 95 : 1

 Pip springs replaced and clamp finger dot replaced.  Uniformity ok.

 7/8/10

 2.06um

 252A

 82 : 1

 After actuator switch on He valve adjusted.

 7/8/10

 1.73um

 169A

 102 : 1

 Temp dot test for 60 mins, did not reach 130C.  Ave depth 104um.

 7/13/10

 2.04um

 119A

 171 : 1

 Reinstalled the electrode teflon spacers (pips).  Adjusted the He bypass flow and also adjusted the He flow restriction valve to the chamber

 8/18/10

 1.93um

 140A

 138 : 1

 Before lip seal change

 8/18/10

 1.98um

 119A

 166 : 1

 After lip seal change

 8/19/10

 1.68um

 192A

 88 : 1

 Investigations of reports of decreased Si ER and increased PR ER.  Also looking into the SI ER decreasing with each run. Pr ok, but Si is low. 10 min etch.  Zygo

 8/19/10

 1.7um

 144A

 118 : 1

 See above.  60 min etch.  Si read by microscope

 8/19/10

 1.57um

 145A

 108 : 1

 See above.  10 min etch.  Zygo

 8/20/10

 1.48um

 151A

 98 : 1

 Used temp dots, less than 54C.  60 min etch, read by microscope.

 8/24/10

 -

 -

 -

 Used DEP TEST recipe to get dep rate, 10 mins.  Dep rate = 1172A/min, nanspec with oxide program.

 8/24/10

 1.73um

 146A

 118 : 1

 Looking into heat as a cause of decreased Si ER.  Run DEEP for 60 mins, then ran Dep rate test, and two 10 min quals.

 8/24/10

 1.74um

 136A

 128 : 1

 See above.

 8/27/10

 -

 -

 -

 DEP-TEST run again, same as 8/24 except APC set to 66%, chamber press = 17mT, Dep rate = 1050A/min

 9/30/10

 2.12um

 205A

 103 : 1

 Tests after He metering valve replaced; He flow = 3.0max, read out 2.4sccm, He press = 9.79.

Etcher idle more that 10 hours, 20 DEEP condition followed by six wafers, DEEP 00:10:00.  Wafers run one right after another.

  9/30/10

 2.02um

 200A

 101 : 1

 

  9/30/10

 1.9um

 187A

 102 : 1

 

  9/30/10

 1.9um

 188A

 101 : 1

 

  9/30/10

 1.78um

 177A

 101 : 1

 

  9/30/10

 1.74um

 176A

  99 : 1

 

 10/5/10

 1.81um

 185A

  98 : 1

 He flow = 3.8max, read out 3.66, He press = 9.77 Wafers run one right after another.

 10/5/10

 1.77um

 182A

  97 : 1

 

 10/6/10

 1.92um

 210A

  91 : 1

  He flow = 3.0max, read out 2.47, He press = 9.78 Wafers run one right after another.

 10/6/10

 1.84um

 192A

  96 : 1

 

 10/7/10

 1.83um

 234A

  78 : 1

 Tests done after SF6 reservoir by-pass installed to track down decreasing Si etch rate as wafers run sequentially.  Tool idle for 15 hours, 20 min conditioning, DEEP 00:10:00.  Slight increase in PR etch rate may be due to SPR220.  Earlier tests done using 3612.

 10/7/10

 1.68um

 230A

  73 : 1

 

 10/7/10

 1.72um

 227A

  76 : 1

 

 10/7/10

 1.65um

 216

  76 : 1

 

 10/13/10

 1.67um

 246A

  68 : 1

 Tests after turbo replaced and exhaust lines cleaned.  SF6 by-pass still in place, 20 min conditioning, DEEP 00:10:00.

 10/13/10

 1.63um

 258A

  63 : 1

 

 10/13/10

 1.67um

 248A

  68 : 1

 

 10/13/10

 1.67um

 236A

  71 : 1

 

 10/14/10

 1.74um

 243A

  72 : 1

 Dry pump replaced, SF6 by-pass still in place, 30 min conditioning, DEEP 00:10:00.

 10/14/10

 1.74um

 243A

  72 : 1

 

 10/14/10

 1.71um

 243A

  70 : 1

 

 1/11/11

 2.0um

 85A

 235 : 1

 After annual winter shutdown.  Three wafers run for 00:10:00 using DEEP.

 1/11/11

 2.0um

 73A

 274 : 1

 

 1/11/11

 1.96um

 69A

 284 : 1

 

 1/11/11

 1.75um

 171A

 102 : 1

 Wafer run for 01:00:00 using DEEP

 2/10/11

 1.90um

 207A

 92 : 1

 Monthly qual- wf #1

 2/10/11

 1.86um

 206A

 90 : 1

 Wf #2

 2/10/11

 1.92um

 204A

 94 : 1

 Wf #3

 2/11/11

 1.95um

 210A

 93 : 1

 After turbo replaced

 3/14/11

 1.82um

 199A

 91 : 1

 March qual- 3 wafers

 3/14/11

 1.88um

 199A

 94 : 1

 Wf #2

 3/14/11

 1.82um

 210A

 87 : 1

 Wf #3

 4/1/11

 2.13um

 211A

 101 : 1

 April qual- one wafer quick check

 5/11/11

 1.63um

 186A

 88 : 1

 After lip seal replaced. chips removed from chamber

 5/12/11

 1.60um

 204A

 78 : 1

 After tool use- looking for improved ER's

 5/26/11

 2.10um

 217A

 97 : 1

 One wafer quick check

 8/10/11

 1.69um

 148A

 114 : 1

 Test after reports of undercutting and burnt resist

 8/11/11

 2.07um

 172A

 120 : 1

 Test after repairs; He pressure turned back to 9.9T, lip seal replaced and chips removed from around wafer lifter.

 8/18/11

 2.1um

 198A

 106 : 1

 Test after report of lower than usual Si ER.  Test ok.

 9/15/11

 2.01um

 224A

 90 : 1

 Monthly qual

 10/4/2011

 1.81um

 194A

 93 : 1

 Monthly qual and user complaints of wf breakage and fast etch rates

 10/11/11

 1.57um

 174A

 90 : 1

 Qual after lifter burr polished off.  Wafer breakage has gone down.

 11/1/11

 2.01um

 256A

 78 : 1

 Monthly qual.

 2/14/12

 2.11um

 236A

 89 : 1

 Quals after annual shutdown and lab renovations.  Wafer #1

 2/14/12

 2.11um

 232A

 90 : 1

 Wafer #2

 3/2/12

 2.3um

 259A

 89 : 1

 

 3/29/12

 2.12um

 285A

 74 : 1

 Monthly qual

 4/26/12

 2.38um

 287A

 83 : 1

 After He flow set back to 3.75 from 5.0

 6/8/12

 1.98um

 234A

 85 :1

 

 6/27/12

 2.24um

 232A

 97 : 1

 After C4F8 replaced

 7/6/12

 1.96um

 221A

 89 : 1

 After C4F8 line flushed

 7/27/12

 2.27um

 241A

 94 : 1

 He flow a bit high- 4.03

 10/2/12

 2.06um

 240A

 86 : 1

  Monthly qual

 11/10/12

 2.38um

 233A

 102 : 1

  Monthly qual

 1/8/13

 1.96um

 258A

 76 : 1

 Qual after annual Winter shutdown

 10/17/13

 2.16um

 175A

 123 : 1

 

 12/5/13

 2.6um

 259A

 100 : 1

 Qual before Winter Shutdown

 1/10 14

 2.57um

 236A

 109 : 1

 Qual after Winter Shutdown

 2/7/14

 1.99um

 285A

 69 : 1

 Qual after user report of low ER.  SF6 unstable during etch cycle.

 5/22/14

 2.4um

 286A

 84 : 1

 Qual after very fast ER reported.

 

Qualification Results

 

 

Recipe Conditions

Machine Status States

Red: Tool is in shutdown due to serious hardware or software issues.  Maintenance staff has been notified.

Yellow: Tool has an issue that will allow for the running of some but not all recipes.  For example, a gas not common to all recipes is under repair/observation.

Green: All recipes and processes may be run. 

Process Modules

Preparing Wafers for Through Etching

If you etch holes completely through the STS, you need a support wafer attached to the back. Follow the steps below:

Note: Good resist adhesion is dependent on a dry surface. If the wafers haven't recently come out of a high temperature furnace (out for more than 1 hour), they should get a singe at 150C for 30 minutes.

  1. Singe wafers @150C for 30 minutes.
  2. Coat a backing (support) wafer with 1.65um 3612 resist using Program 8 in manual mode (you don't want to prebake the wafer).
  3. Place your device wafer on top of the support wafer and align the flats as best you can.
  4. Place the wafers on a hotplate (set at 105C) and place foil over the wafer to protect the surface. Put the weight on top of the foil (the weights are near the hotplate).
  5. Bake on the hotplate for 1 hour.
  6. Coat your wafer with the SVGCOAT using program 1 on the prime station and program for the desired thickness on the coat station ( for example Program 4 for 7um). You may choose not to use the edge bead removal steps.
  7. Expose, develop and postbake.
  8. Do an additional post bake in the 90C (45-60 mins) or 110C (30 mins) to further harden the resist.