EE527
Stan dard Oper atin g Proced ure: Spin-on-Glass, Surface Level Ch aracteri zati on
Tom Chr istian sen
Tami Erickson
Final Project
Standard Operating Procedure:
Spin-on-Glass
Surface Level Characterization
By:
Tom Christiansen
Tami Erickson
Course:
EE 527
Lecturer:
Karl Böhringer
Deadline:
June 8, 2000
EE527
Stan dard Oper atin g Proced ure: Spin-on-Glass, Surface Level Ch aracteri zati on
Tom Chr istian sen
Tami Erickson
Spin-on-Glass Background Information
Spin-on-glass (SOG) is a type of glass that can be applied as a liquid and cured to form a layer of glass
having characteristics similar to those of SiO 2. SOG is mainly used for planarization and as a dielectric
material.
The SOG used in the EE 527 course is made by Honeywell (T-11, type 311). Characteristics for the
different Honeywell types of SOG are listed below [1].
Product
Types
Performance
Thickness
[Å]
Shelf-life
@ 4/C
Dielectric
constant
Refractive
index
T-11
211
311
-
1700-2400
2300-3500
6 months
3.8
1.39 ±0.01
T-12B
312B
412B
512B
- Up to 0.5mm single coat thickness
- Extremely low shrinkage upon cure
- Exceptional crack resistance up to
2mm
- Lower dielectric co nstant than that of
SiO 2
- Excellent small gap fill capability
2900-3200
3900-4200
4900-5200
6 months
3.1 ±0.1
1.38 ±0.01
T-14
214
314
-
2000-2300
2700-3000
# 6 mo.
3.8
1.38
High crack resistance
Low shrinkage upon cure
Thermally stable
Good electrical characteristics
Excellent adhesion to Si, thermal
oxide, CVD oxides, and Al.
Superior dielectric properties
Low moisture contents
Better crack resistance
Lower shrinkage upon cure
Thermally stable
Good gap fill properties
Adhesive to Si, thermal oxide, CVD
oxides, and Al
The T-11 and T12B series belong to the methylsiloxane family polymers.
T-14 series is a series of siloxane polymers specially formulated to fill narrow, high aspect ratio space
without voiding. Furthermore it is useful for planarizing multi-level metal devices.
1
EE527
Stan dard Oper atin g Proced ure: Spin-on-Glass, Surface Level Ch aracteri zati on
Tom Chr istian sen
Tami Erickson
Standard operating procedure: Spin-on-glass
1)
Bring SOG up to roo m temperature by leaving it in the lab for 30 minutes.
2)
Singe (heat 1 minute at 80/C)
3)
Apply SOG using same technique as photoresist (spin at 3000 RPM)
4)
Bake at 80/C for 1 minute
5)
Bake at 150/C for 1 minute
6)
Bake at 250/C for 1 minute
7)
Cure in furnace at 425/C for 1 hour using N2
If only two heating plates are available, steps 4 – 7 may be reduced to:
1 – 3) As above
4)
Bake at 80/C for 1 minute
5)
Bake at 250/C for 1 minute
6)
Cure in furnace at 425/C for 1 hour using N2
If only one heating plate is available, the procedure may be further reduced:
1 – 3) As above
4)
Bake at 250/C for 1 minute
5)
Cure in furnace at 425/C using N2
Note that the lifetime of the SOG is dramatically reduced when the product is heated to roomtemperature. The remaining SOG must t herefore be discarded after use. A 1000ml bottle is $725, so
it pays to apply glass to several wafers at once!!!
2
EE527
Stan dard Oper atin g Proced ure: Spin-on-Glass, Surface Level Ch aracteri zati on
Tom Chr istian sen
Tami Erickson
Surface Level Characterization Equipment Description
The lab setup for characterizing the surface level of a wafer is shown below.
Fig. 1: Surface level characterization setup
The wafer is loaded onto the analyzer, which mechanically measures the surface height of the wafer.
Below is a detail view of the analyzer controls.
The wafer is placed on the wafer chuck and
the surface level is measured with a needle
moved by an electric motor. The needle’s
height (Z-axis position) is adjusted using the
top handle. Discrepancies in the vertical
direction (along the Z-axis) can be corrected
using
the
slope
magnific ation
is
adjust
knob.
selected
X-axis
using
the
magnification knob. With the knob in x20
position, the magnification is approximately
1:100 (1mm on wafer equals 100mm on
Fig. 2: Analyzer controls
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EE527
Stan dard Oper atin g Proced ure: Spin-on-Glass, Surface Level Ch aracteri zati on
Tom Chr istian sen
Tami Erickson
printout). Do not use the x100 position (1:500) as this uses too much paper.
The output from the analyzer is logged on a printer, which is shown in Fig. 3.
Fig. 3: Printer
Fig. 4: Power supply
The printer uses an electrical current to write on the paper, so a smell of burning sulfur – like the smell
of fireworks – is quite normal during operation. Holes are indicated on the right side of the paper,
bumps on the left. Top cover can be opened by pulling the knob on t he right-hand side of the cover.
The power supply (Fig. 4) has two functions: It controls the Z-axis magnification and it provides
power to the entire system. Since the power supply uses vacuum tubes it should be allowed a warmup period of at least five minutes prior to use.
Z-axis magnification ranges: 1: 10mm/cm
4: 1mm/cm
2: 5mm/cm
5: 0.5mm/cm
3: 2mm/cm
6: 0.2mm/cm
4
EE527
Stan dard Oper atin g Proced ure: Spin-on-Glass, Surface Level Ch aracteri zati on
Tom Chr istian sen
Tami Erickson
Standard operating procedure: Surface Level Characterization
Important: Do not lean onto table or equipment while making measurements.
1)
Turn on power and allow a five minute warm-up period
2)
Select magnification on power supply
3)
Load wafer so area of interest is below needle (needle moves from left to right)
4)
Turn vacuum on
5)
Use needle height coarse control to gently lower needle until it touches wafer. Turning handle
CCW moves needle down; CW moves needle up
6)
Adjust needle height until printer pen is within the middle b of the paper
7)
Use pen position fine control to center pen on paper
8)
Start analyzer by moving Start/Stop handle to the right
9)
Start printer by moving paper feed On/Off handle to t he right
10)
If printout is not satisfactory see adjustments below
11)
After measurement: Turn off printer, pull paper to desired length and tear off, turn off
analyzer, raise needle above wafer, turn vacuum off, remove vacuum hose, remove wafer, put
vacuum hose back on, set the magnification knob on power supply to 1 (10mm/cm), turn off
power supply.
Adjustments
Note: Before all adjustments: Turn printer off and raise needle.
If track marks on printout moves diagonally:
Towards left ( \ ): Turn slope adjustment knob CCW
Towards right ( / ): Turn slope adjustment knob CW
Variations on track marks are too small (too low resolution): Select higher magnification on
power supply.
After adjustments: Repeat procedure from step 5.
5
EE527
Stan dard Oper atin g Proced ure: Spin-on-Glass, Surface Level Ch aracteri zati on
Tom Chr istian sen
Tami Erickson
References
[1]:
http://www.electronicmaterials.com/businesses/wfm/dielectrics/index.htm#spinglass
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