Unity® Sacrificial Polymer
Processing Overview
Introduction
Unity Sacrificial Polymers are experimental materials for interlevel dielectric applications. Unity is packaged in bottles containing the thermoplastic polymer dissolved in a simple hydrocarbon (mesitylene). A typical formulation has a viscosity of 1000 centipoi and 23% solids. The solutions are filtered to 0.2 µm, and total metals are less than 5 ppm in solution
Process Overview
Step 1: Substrate Preparation: Clean substrates
Step 2: Spin coating: Dispen Unity onto wafer and t spin conditions to 500 rpm for 10 conds
followed by 1000-4500 rpm (dependent upon desired thickness) for 60 conds.
Step 3: Solvent Flash: Place coated wafer onto hotplate at 100 o C for 5 minutes.
Step 4: Cure: Excluding all contact with oxygen (<100 ppm O2)! Cure Unity coated wafers at 200 o C for 2
中华路小学
hours depending upon system ud. Possible curing systems are described under the Cure ction in传染病疫情报告
this Process Guide.
Step 5: Pattern Unity: Metalize Unity utilizing DC sputtering.
Pattern metal utilizing standard photolithography techniques
Etch away expod metal to eventually expo Unity using a metal etchant
Remove photoresist (optional).华佗学医
Reactive Ion Etch metal etch mask pattern into Unity. Process technique described in Process
Guide. Etch time dependent upon Unity thickness.
Remove metal etch mask to reveal patterned Unity
Step 6: Encapsulation: Encapsulate patterned Unity with desired material. Possible materials include: SiO2
by PECVD, sputtered metal, polyimide, etc.
Step 7: Decomposition: Unity decomposition is performed using a nitrogen purged tube furnace (<5 ppm
O2). Starting at 100o C, heat to 350 o C with a 5 o C/minute ramp and 350 o C to 425 o C with a 1 o C/minute ramp and soak at 425 o C for 1-2 hours depending upon Unity thickness. (5 um thickness will decompo in ~90 minutes.) Cool to below 100 o C at 5 o C/minute. Remove wafers.
Unity Sacrificial Polymers are now ready for subquent processing.
See attached Process Guide for further details.
Introduction
Unity Sacrificial Polymers are experimental materials for interlevel dielectric applications. Unity is packaged in bottles containing the thermoplastic polymer dissolved in a simple hydrocarbon (mesitylene). A typical formulation has a viscosity of 1000 centipoi and 23% solids. (Formulations may be tailored upon request) The solutions are filtered to 0.05 µm, and total metals are less than 50 ppb in solution. Total metals tested for include Al, Ba, Ca, Co, Cu, Fe, Li, K, Mg, Mn, Mo, Na, Ni, Pd, Sn, Sr, Ti, V, Zn.
Equipment & Utilities
This guide was developed using a Class 1000 clean room temperature-controlled to 22o C (72o F) and relative humidity of 50%.
Spin coating: A Brewer Science CEE Model 100CB Spinner calibrated from 1000 to 4000 rpm was ud for coating the polymer.
Solvent Flash: A well-ventilated hotplate capable of maintaining 100-120o C.
Curing: A well-ventilated oven with an oxygen free (<100 ppm) nitrogen purge. This oven should hav
e temperature control to at least 250o C.
Substrate Preparation
Appropriately clean substrates in order to remove any moisture, particles or residue. A recommended cleaning procedure is a quential rin of acetone, methanol, isopropanol, and deionized water for about 20 conds each. Adhesion promoter is not required when using Unity Sacrificial polymer. Unity adheres to a variety of substrates. As measured using IPC-TM-650 and ASTM D3359-95a tape test protocols.
Table I: Results of Adhesion Test
Substrate Cu Au Al Cr Ti Si SiO
2
IPC Pass Pass Pass Pass Pass Pass Pass
ASTM Pass Pass Pass Pass Pass Pass Pass
Spin Coating
Statically dispen polymer solution on center of the substrate (for example, u approximately 2.0 ml of polymer solution for a 100 mm wafer). Spread the polymer solution at 500 rpm for 5-10 conds. Accelerate to the desired speed and hold for 60 conds. Acceleration rates can be varied between 250 and 4000 rpm/c.
A typical spin speed curve is shown in Figure 1. Unity Sacrificial Polymer solution viscosity may be tailored to meet specific thickness targets upon request. Once tailored specifically to the customers needs, Unity Sacrificial Polymers can be spun in thickness ranging from tens of microns to hundreds of nanometers.
Figure 1: Typical Unity Sacrificial Polymer Spin Speed Curve After Bake
Solvent Flash
猪腰子怎么炒好吃
The films are placed horizontally on a well-ventilated hot plate and softbake at 100-120o C for 5 minutes on a hot plate. Do not place the sample on a chill plate after the solvent flash.
Shrinkage
The film thickness was measured before and after the cure cycle (e next page for cure conditions). The film shrinkage was less than 0.5%.
Cure
It is important to exclude all contact with oxygen (<100 ppm) during the curing cycle. Two methods can be ud.
I.Nitrogen Purged Quartz Tube Furnace (Preferred Method):
The substrate is placed in a quartz wafer boat in the vertical position at room temperature.
Ramp the furnace at 5o C/min to 200o C.
Hold temperature at 200o C for 2 hours.
Cool furnace at a nominal rate of 5o C/min to below 100o C.
Samples can be removed for subquent processing.
II.Vacuum Oven (Alternate Method):
Place the substrate in the vacuum oven below 100o C.
Seal the oven.
Purge the oven with N2 and partially evacuate the chamber. Repeat this procedure two times.
Evacuate the chamber to a pressure less than 100 mtorr.
Ramp temperature at a nominal rate less than 5o C/min to 200o C.
Hold temperature for 2 hours.
Cool the vacuum oven to below 100o C.
After cooling, nitrogen is ud to break the vacuum.
Samples can be removed for subquent processing.
Pattern Unity
Metallize
U DC sputtering to deposit metals such as Cu, Au, Al, Cr, Ti onto Unity Sacrificial Polymers. Metal tie-layers are not necessary for adhesion but may be ud.
Metal Deposition is accomplished with a DC magnetron sputterer operating between 300 and 3000 W at 6 mtorr.
Sputtered metals adhere directly to Unity as measured using IPC-TM-650 and ASTMD3359-95a tape test protocols.
Deposited
Metal Cu Au Al Cr Ti
IPC Pass Pass Pass Pass Pass
ASTM Pass Pass Pass Pass Pass
Reactive Ion Etch
This data was generated using a Plasma Therm 700 Reactive Ion Etcher at ambient temperature. U 40 sccm Ar, 15 sccm O2 and 5 sccm CHF3 at 300 watts and 300 mtorr. The conditions produce an etch rate of 250 nm/minute. Under the conditions, the etch rate of Shipley 1827 is 0.5
µm/minute.
Unity Sacrificial Polymer Processing Guide
Page 5 of 6 Encapsulation
PECVD SiO
2
Maintain the temperature at or below 200o C for SiO2 deposition.
搜狗兼容模式Polymer Decomposition
Nitrogen Purged Quartz Tube Furnace: (<5 ppm O
2)
The substrate is placed in a quartz wafer boat in the vertical position at a temperature -between ambient and 100o C. The furnace is heated to 350o C with a 5o C/minute ramp and 350 o C to 425 o C with a
1 o C /minute ramp and soak at 425 o C for 1-
2 hours depending upon Unity thickness. (5 um thickness will decompo in ~90 minutes). Cool to below 100 o C at 5 o C/minute. Samples can be removed for subquent processing. Also recommended is an end cap and oil bubblier to prevent back stream oxygen contamination.
Shelf Life
Guaranteed for 6 months
Allow 2 hours for a 1 liter bottle to equilibrate to room temperate prior to u.
Trouble Shooting Guide
处女双子Edge Bead:
Can be minimized with longer ramping times and/or varying the acceleration rate.
May need to adjust viscosity of the dielectric polymer solution by adding filtered mesitylene. Bubbles Entrapped in the Film:
U a Millipore pump and filtering device (e.g., Millipore PI-250) to eliminate bubbles entrapped in film.
Film of Wrong Thickness:
Verify the spin speed curve and spinner calibration.
Add filtered mesitylene to correct for solvent loss.
九叶派Long Strings of Polymer Formed During Spinning or Back Splashing of Polymer on to the Wafer:
Employ a back-side rin with mesitylene.
Film Crazing:
芝士和黄油的区别Check oxygen content of curing oven.
