Nextral HDP-RIE User’s guide

THE CENTER FOR

NANOSCIENCE AND

NANOTECHNOLOGY

NEXTRAL HDP-RIE

User’s Guide

Nextral HDP-RIE User’s guide 2

Launching Vacuum

1 Login onto the Control System

2 If necessary, log onto the machine :

User: mark

Password: 7926

3

Verify the VACUUM STATUS

If VACUUM STATUS is STANDBY,

press and hold VACUUM button for several seconds

VACUUM STATUS will change to

LAUNCHING TMP and turbo molecular pump will begin

to accelerate

Prepare chuck and sample for insertion while waiting for VACUUM STATUS to change to

VACUUM

_____________________________

If VACUUM STATUS is VACUUM ,

Continue to next step (step 4)

Nextral HDP-RIE User’s guide 3

Cleaning the Chuck for Small Samples

4 Place clean wipes on perforated metal frame to the side of chamber

5 Remove chuck from desiccator and place on wipe

6 Place a finger in the notch and carefully lift the plastic O-ring

to remove

7

Spray IPA on new wipe and gently

clean O-ring by holding wipe in

place and rotating O-ring

Gently dry plastic O-ring

with N2 gun

8 Replace plastic O-ring on chuck

Nextral HDP-RIE User’s guide 4

Cleaning the Chuck for Wafers I

9 Place clean wipes on perforated metal frame to the side of chamber

10 Remove chuck from desiccator and place on wipe

11

Grasp graphite ring from sides and, together with O-ring, remove

from chuck

Place on second wipe

12 Carefully remove the plastic O-ring from the graphite ring

13 Spray IPA on new wipe and gently

clean O-ring by holding wipe in place and rotating O-ring

Nextral HDP-RIE User’s guide 5

Cleaning the Chuck for Wafers II

14 Gently dry plastic O-ring

with N2 gun

15 Replace O-ring on graphite ring

16 Place wafer on chuck in wafer depression

17 Replace graphite ring on chuck

Nextral HDP-RIE User’s guide 6

Adhering Small Samples to Chuck with Grease

18

Applying grease can be messy!

Wear two sets of gloves!

Constantly check gloves when using grease!

After application remove

top layer of gloves!

19

Hold chip by its edges.

With small swab, place small amount of grease (e.g. Apeizon)

on the back of chip

With swab, spread grease to form thin, uniform layer, leaving 1-2 mm border at chip edges free of grease

20 Place chip in center of chuck for small samples

21

Check gloves for contamination!

Check chuck and chip for grease contamination!

Remove top layer of gloves

22 At edges, press chip down

Check to see if chip sits level

If not, press chip at edges to level

Nextral HDP-RIE User’s guide 7

Inserting Sample into Chamber

23 When VACUUM STATUS is VACUUM

Press the vent button

24

When chamber is vented extract slide from machine

Grasp chuck by metal bottom

and graphite top (NOT BY PLASTIC O-RING)

Place other hand through

bottom of chuck holder

Lower chuck into hand, aligning chuck notch with

alignment wedge

25 If using chuck for wafers, align

O-ring helium exhaust holes with cut out in chuck holder

26 Move chuck back and forth slightly

to check that it is seated properly in chuck holder

27

Push slide into chamber.

Holding it closed, push and hold VACUUM button for several seconds

until vacuum engages

28 Wait until PENNING GAUGE reads 10 nBar

a a

Nextral HDP-RIE User’s guide 8

Recipe Name Disambiguation

29

Important!

There are two general types of etch programs:

1) Etch programs for wafers 2) Etch programs for small samples (chips)

Etch programs for wafers are designated by a “w_” at the beginning of the program name

Etch programs for small samples include only the program name

Example:

w_RES_RIE is for resist etching on wafers RES_RIE is for resist etching on small samples

Nextral HDP-RIE User’s guide 9

Loading an Etch Program

30

After Penning gauge reads 10 nBar

Click OPERATE NEW

Choose appropriate etch program from SELECT PROGRAM list

and click OK

When screens reads:

LOAD IN PROGRESS

DO NOT touch mouse or keyboard

31 If the etch time is fixed, program will load automatically

32

If etch time is variable,

enter the appropriate time in pop-up window

1) Click in the ACTUAL field for

Etching

2) Input the new time and hit Enter to save the new time

3) Hit Enter again to load the

etch program

33

Click OPERATE RUN

Enter new WAFER REFERENCE name (8 digits, beginning with re-search group name) and hit Enter

Example: SHCHM003

HANEI244

Nextral HDP-RIE User’s guide 01

Processing I—Stabilization

34

Program will begin to step through process steps:

1) Stabilization 2) Heating 3) Send gasses 4) Ignition 5) RF matching 6) Etching 7) Cooling

35

Stabilization

If using EPD, optimize spot position, spot size and signal amplitude

Spot position:

Rotate x– and y-axis micrometers,

and , respectively

until spot is located in

appropriate area

Spot size and signal amplitude:

Rotate aperture and focus rings,

and , respectively

on interferometer lens until the laser spot is as small and

round as possible

Before optimization

After optimization

Nextral HDP-RIE User’s guide 00

Processing I—Stabilization

36

Stabilization (cont’d)

Adjust aperture ring until

yellow interferometer signal on

screen is between 3-5 V

This procedure will increase/decrease the signal amplitude

The max/min of laser signal amplitude is given in yellow

(e.g. 0.0 V to 10.0 V).

The signal indicated in the picture is about 4.8 V

If necessary, double click on the screen and change the max/min

of the laser signal setting

37

After the laser is positioned properly and the spot size and signal intensity

are corrected

Click OPERATE –> EXIT STEP

To continue to the next processing step (e.g. HEATING, SEND GASSES,

ETC.)

Nextral HDP-RIE User’s guide 02

Processing II—RF Matching

38

RF Matching

RF matching should be automatic

Machine will vary LOAD and TUNE settings as necessary in order to

reduce reflected power

If matching is not successful, REFLECTED POWER will be red and you MUST stop the process

To stop process from ANY step:

Click OPERATE

Click GOTO STEP

Click COOLING

Nextral HDP-RIE User’s guide 03

Processing III—Etching

39

If performing timed etch or automatic EPD,

Processing will proceed

automatically.

When the time is up or the EPD detects the end the machine will

automatically continue to the COOLING step

40

If using interferometer without automatic end point detection

Continue with etch until signal

changes (e.g. sinusoid flattens to a straight line or vice versa)

Wait about 5% more in etch time

(not total time!)

Click OPERATE

Click EXIT STEP

To continue to COOLING step

41 After COOLING step the process

is finished,

Click SAVE in window that appears

Nextral HDP-RIE User’s guide 04

Extracting Sample from Chamber

42

After a completed process, wait about 5 minutes before venting

chamber, then

Click OPERATE

Click VENT

To vent the chamber

43

When chamber is vented

Pull slide out of chamber

Place hand through bottom of chuck holder and lift chuck from the bottom,

Grasp chuck by metal bottom

and graphite top (NOT BY PLASTIC O-RING)

Place chuck on wipes to the perforated side of the chamber

44

Push slide into chamber and hold slide closed

Push VACUUM button for several

seconds until vacuum engages

Nextral HDP-RIE User’s guide 05

Removing Sample from Chuck

45

For small samples,

Remove sample from chuck with tweezers

Clean grease from back of chip

with IPA on swab

Clean grease from chuck with IPA on clean wipe

Replace chuck in desiccator

46

For wafers,

Lift graphite ring and place on sec-ond wipe to side

Lift wafer from chuck with tweezers

and remove

Replace graphite ring on chuck

Replace chuck in desiccator

47 Log off Control System

Nextral HDP-RIE User’s guide 06

Editing Etch Programs I

48

In the NAPS program, click EDIT

Then, click OPEN

Scroll in the list to find the program you wish to edit

and click to highlight

Click OK to open it

49

Programs are comprised of steps:

Stabilization, Heating, Ignition, RF Matching, Etching, Cooling

To step through the program, click

the NEXT BUTTON

50

To change a parameter click the parameter in the right window

In the SET TO field, type the new

value and click enter

51

Values for gas flows and work pressure should not change

between SEND GAS, IGNITION, RF MATCHING and ETCHING

steps

Nextral HDP-RIE User’s guide 07

Editing Etch Programs II — RF Matching

52

Values for LOAD and TUNE

must be found empirically

To find appropriate values for

LOAD and TUNE ,

run a dummy wafer first

In the program editor enter values

for LOAD and TUNE from a similar

program

53

Values for LOAD and TUNE

should not change between

IGNITION, RF MATCHING and ETCHING steps

54 Save the process with a different name if altering an existing process

55

Run the process.

If the machine finds new values of LOAD and TUNE that are different than those saved in the recipe write them down and change them in the

recipe after the process has finished. Save the process again with the new

values LOAD and TUNE

Nextral HDP-RIE User’s guide 08

End Point Detector (EPD) I

56

Go to the ETCH step in the

of a program in the Program Editor

Click the square under EPD1

at the bottom of the screen

57

The EPD has three states: ON, OFF and RUN

ON—Interferometer is running but

will not stop the process automatically

OFF—Interferometer is not running

RUN—Interferometer is running and

will stop the process automatically

58

Curve Type Interferometry - for use when etching

transparent layers such as SiO2, Si3N4, or Si. EPD will calculate the etch rate with the total thickness.

Max/Min – for use when etching

non-transparent layers such as met-als. The end point can be detected only after the maximum/minimum of the optical signal.

Slope– for use when etching

non-transparent layers such as met-als. The signal can either increase or decrease. The end point will be de-tected at the beginning or the end of the slope depending on the pro-grammed parameter.

Nextral HDP-RIE User’s guide 09

End Point Detector (EPD) I

59

When using interferometer, a signal will be present on the screen

Opaque materials will normally pre-

sent a flat line

Transparent or semi-transparent materials

will present a sinusoid

60

Input correct index of refraction for material to be etched

If necessary, set max thickness and max time to greater than necessary

If using automatic EPD (i.e. RUN) set the constant over etch (COE) or per-cent over etch (POE) to appropriate

values

5% of etch time is generally considered appropriate

Click OK to return to process editor

Nextral HDP-RIE User’s guide 21

Troubleshooting

61

62

63

Nextral HDP-RIE User’s guide 20

Troubleshooting

64

65

66

Nextral HDP-RIE User’s guide 22

Troubleshooting

67

68

69