Utah-94-721002-System-Manual.pdf - 第280页

^ää=lfmq=póëíÉãë l ñÑçêÇ =fåëíê ìãÉåíë =m ä~ëã~=q ÉÅÜåçäçÖó== System Manual Auto/manual switch: In the ‘Auto’ position, the unit will attempt to tune for minimum reflected RF power. In the ‘Manual’ position, the capacito…

System Manual lñÑçêÇ=fåëíêìãÉåíë=mä~ëã~=qÉÅÜåçäçÖó== ^ää=lfmq=póëíÉãë

(corresponding to RV101) to position ‘a’ and begin turning the potentiometers anti-

clockwise again until the oscillations stop.

15) Confirm the automatching behaviour, increasing the RF power to maximum in small

steps, repeating Steps 10 to 13 if necessary.

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WARNING

THE FOLLOWING ADJUSTMENT INVOLVES WORKING ON THE SYSTEM WITH

PANELS/COVERS REMOVED. IT SHOULD ONLY BE CARRIED OUT BY TRAINED

PERSONNEL WHO ARE AWARE OF THE HAZARDS INVOLVED.

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The DC bias / Peak-to-peak switch is located on the outer case of the AMU, adjacent to RV1

(null adjustment potentiometer). See Fig 1, page 3.

This switch selects one of two sensing output signals from the AMU:

DC bias: This switch setting is the default position. The output is a SCALED dc

voltage proportional to the RF-induced self-bias on the electrode,

sometimes called the 'DC bias'. This is a negative offset voltage on the

electrode with respect to ground, which is inverted and conventionally

referred to as a positive value, typically 100 - 600 Vdc. Normal scaling can

read up to 1000 Vdc. This signal is read by the front-end software with

correct scaling on OIPT tools.

Peak-to-peak: The output is an UNSCALED dc voltage related to the peak-to-peak value

of the RF signal at the output of the automatch. This can be useful when

the scaled dc bias is inaccessible, for example if the electrode has no dc

contact to the plasma because a quartz carrier plate masks the whole

electrode. The value displayed on the PC screen will be an arbitrary value,

not a true peak-to-peak value, but can still be a useful monitor.

Note that the software has no knowledge of the switch setting and is scaled only for the dc

bias setting.

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If the automatch has been set to ‘auto’, the unit will attempt to reduce the reflected RF

power to minimum without the need for operator adjustments. It will normally reduce

reflected power to less than 2% of forward power.

Use manual matching for the following:

a) One or both capacitors has driven to a limit.

b) To discover if a match exists within the range of the matching unit.

The adjustment panel for the automatch is located behind a hinged cover. Opening the cover

reveals the following controls and indicators:

OIPT Automatch Unit

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^ää=lfmq=póëíÉãë lñÑçêÇ=fåëíêìãÉåíë=mä~ëã~=qÉÅÜåçäçÖó== System Manual

Auto/manual switch: In the ‘Auto’ position, the unit will attempt to tune for minimum

reflected RF power. In the ‘Manual’ position, the capacitors

positions are controlled manually.

C1 max/min switch: In manual mode, this switch can be used to drive capacitor C1

towards maximum or minimum.

C2 max/min switch: In manual mode, this switch can be used to drive capacitor C2

towards maximum or minimum.

Note that capacitor positions are displayed as a three-digit number

from 000 (minimum) to 999 (maximum).

Display Selector

Switch:

The RF monitoring positions display the analogue voltages on the

remote control lines to the RF generators, as a service aid. The Hi/Lo

position reads a high (>9V) value when the wafer bias RF supply is at

full scale, and a low (<1V) value when this supply is scaled back to one-

tenth full power. This feature improves resolution of RF low power.

C1 park.

Potentiometer:

This control can be fitted either to the control panel or on the AMU

control board. The automatch will drive C1 to this pre-set position

when the RF is turned off, if the unit is set to ‘auto’

C2 park.

Potentiometer:

This control can be fitted either to the control panel or on the AMU

control board. The automatch will drive C2 to this pre-set position

when the RF is turned off, if the unit is set to ‘auto’

OIPT Automatch Unit

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System Manual lñÑçêÇ=fåëíêìãÉåíë=mä~ëã~=qÉÅÜåçäçÖó== ^ää=lfmq=póëíÉãë

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WARNING

HAZARDOUS RF VOLTAGE - CONTACT CAN CAUSE DEATH, SEVERE INJURY

OR BURNS.

ANY WORK REQUIRING THE REMOVAL OF COVERS OR PANELS MUST

ONLY BE PERFORMED BY AUTHORISED PERSONNEL WHO ARE AWARE OF

THE HAZARDS INVOLVED.

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Use the following chart to locate and identify faults. Note that the chart lists typical fault

symptoms and is not exhaustive.

SYMPTOM POSSIBLE CAUSES ACTION

(A) Drive motors do

not respond to

automatic or

manual control

Fuse FS2 blown

Fuse FS1 or FS101 tripped.

Investigate and repair fault, which caused the

fuse to blow. Then renew the fuse.

Investigate and repair the fault, which caused

the fuse to trip. (The fuses will automatically

reset once the fault is repaired.)

Note that these components are semiconductor

fuses which respond to an increase in current

above their rating (approximately 200 mA) by

increasing their internal resistance significantly.

The voltage drop across each of these

components under non-fault conditions is

approximately 0.5V

When tripped by high current, the voltage drop

is almost the full supply voltage i.e. 24V.

After power is removed, the devices require 20

seconds to cool down and reset.

(B) C1 or C2 drive to

min or max

1. C1 or C2 starting too far

from final match position

Adjust park potentiometers (Refer to sub-

section 6.4 (page 20).

2. Match position is out of

accessible range

1. Change process conditions

2. Change component fit in AMU (skilled

personnel only). Refer to sub-section 6.3 (page

19).

min or max and do

not return

manually

Capacitor has travelled past

an electrical limit

1. All vane capacitors only: Continue manual

travel in the same direction (to max if capacitor

is at max). The capacitor will turn fully until it

passes the opposite limit.

2. Readjust limit settings

(D) Plasma does not

strike even though

the reflected power

is low

Gas pressure is too low or

too high

Caution: do not run for > 2 minutes in this

condition. Change gas pressure to 20 - 200

mTorr range (RIE), or 0.5 - 1.5 Torr range

(PECVD)

OIPT Automatch Unit

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