NB SEMIPLATE AU 100 TH Au electroplating process

Transcription

1 NB SEMIPLATE AU 100 TH Au electrplating prcess INTRODUCTION NB SEMIPLATE AU 100 TH is an alkaline, nn-cyanide electrplating frmulatin which prduces a bright, ductile depsit. In cmparisn with ther gld plating prcesses, the NB SEMIPLATE AU 100 TH electrlyte demnstrates exceptinal thrwing pwer that results in gd cverage f recesses, hles and hllws f parts f cmplex gemetry. Depsits frm the NB SEMIPLATE AU 100 TH prcess als exhibit the unique ability t build brightness with increasing thickness. Specific gravity measurements f the depsit cnsistently shw values f 19.1 which indicate freedm f c-depsited plymers generally fund in depsits frm ther systems f similar purity. NB SEMIPLATE AU 100 TH depsits have main applicatins in MEMS prcessing. NB SEMIPLATE AU 100 TH is shipped ready-fr-use, while the AU 100 xxx are cmpunds and used fr mixture and maintenance. NB SEMIPLATE AU 100 TH replaces the frmer prduct versin NB SEMIPLATE AU 100. READ ENTIRE TECHNICAL DATA SHEET BEFORE USING THIS PRODUCT. PHYSICAL PROPERTIES OF THE DEPOSIT Purity 99.9% Hardness 130 t 190 HV 0,020 Cntact Resistance 0.3 Millihms* Depsit weight fr 2.5 micrns 31.6 mg/in² (4.9 mg/cm²) (100 micr inches) *Cntact resistance measured by crss-wire methd with 200 gram lad. MATERIALS REQUIRED Article N. Units Prduct Name Cmment , 5, 10, 20 liters NB SEMIPLATE AU 100 TH ready-fr-use slutin Unit (3l) AU 100 B make up slutin liter Au 100 BRIGHTENER TH , 2, 5 kg Au 100 CONDITIONER liter Au 100 X COMPLEX gld cmplex brightening agent cncentratins f this additive can be varied in wrking slutins based n specific perating preferences maintains the specific gravity and cnductivity f the slutin and cmplexes the gld - - Sdium hydrxide (NaOH, reagent grade, 20% by vlume) Sulfuric acid (H2SO4, reagent grade, 5% by vlume slutin) required t raise the ph required t lwer the ph Rev 2.0 / Page 1

2 EQUIPMENT REQUIRED Tanks (liners) Leaching Plyprpylene, CPVC, unfilled PVC, and plexiglass are recmmended. Vitn is a recmmended gasket material. If any questins arise as t material cmpatibility, cnsult NB Technlgies. Leach all tanks and peripheral equipment thrughly prir t installatin f this prcess. Heating Titanium, stainless steel (type 316) Filtratin Cntinuus filtratin is required. Fiberglass r cellulse can be used t btain a clear filtrate after carbn treatment. Use prperly leached Dynel, r plyprpylene filter cartridges. Rectifiers Sufficient t develp mre than the greatest direct current required with less than 5% ripple at the amperage used. Andes Ventilatin platinated titanium exhaust accrding t lcal regulatins BATH PARAMETERS The fllwing table shws the bath parameters, which shuld be maintained and checked with regular sample analysis. NBT analysis Units Max. upper Upper actin Optimum Lwer actin Lwest Au X g/l 14 13,0 12, ,0 AU 100 BRIGHTENER TH X ml/l Density - g/cm ph (X) ph Stress level - MPa GENERAL PLATING CONDITIONS Parameter Optimum Range Cathde current density [ma/cm²] 1,5 1 6 Flw depending n tl [l/h] Ande t cathde spacing [cm] 5-15 (depends n tl and wafer size) Temperature [ C] 30 RT t 50 Rev 2.0 / Page 2

3 MAKE-UP PROCEDURE T make up 5 liters f wrking slutin the fllwing are required: AU 100 B AU 100 CONDITIONER AU 100 X COMPLEX AU 100 BRIGHTENER TH 1 Unit (3 liters) 675g 600 ml (60 g Au) 325 ml 1. Thrughly clean the plating tank 2. Add AU 100 B unit (3 liters) 3. Heat t 50 C. 4. Add 325ml AU 100 BRIGHTENER TH 5. While stirring, add 675g AU 100 Cnditiner, fill t 80% final vlume (4 liters) and disslve the AU 100 CONDITIONER cmpletely 6. Check ph; while stirring reduce ph t 9.5 using 10% sulfuric acid 7. Add the necessary 600ml Au 100 X COMPLEX. 8. Adjust t final vlume 5l with deinized water. 9. Check and adjust density if necessary (see belw) 10. Check and adjust the ph The slutin is then ready fr use. SPECIFIC PROCEDURES Oxygen plasma befre plating chemical pre-treatment nt recmmended/needed Cleaning f all items with DI befre insertin in electrlyte Wetting f wafer surface with DI water befre insertin int bath (check fr wetting) 1 minute dwelling in bath befre current applicatin SPECIFIC REQUIREMENTS Fixtures and ande shuld be perated in symmetric cnditins t the wafer center (distance f wafer edge t fixture edge, distance f fixture t tank wall, electrical cntacting) Ande material platinated titanium Fixture and thers features f PP, PFTE, POM r cmpatible-prven materials (degreased, leached) OPERATION Cnsistently ptimum depsits frm the NB SEMIPLATE AU 100 TH prcess are easily achieved thrugh cnscientius prcess cntrl. Cntinuus filtratin, vigrus mechanical (nt air) agitatin and gd temperature cntrl are imprtant as well as careful rinsing techniques and the use f a gld strike. Brightness f the depsit frm the NB SEMIPLATE AU 100 TH prcess must be maintained. A dull depsit is indicative f prcess imbalance and will eventually result in decmpsitin f the slutin. T maintain depsit brightness, the gld cncentratin must be maintained within the specified range. If brightness has been lst, add Au 100 BRIGHTENER TH. If this additin is ineffective, make an additin f Au 100 CONDITIONER. If satisfactry results are nt btained, ther prblems exist with the slutin such as metallic and/r rganic cntaminatin r a specific gravity in excess f 1,261g/l. NOTE: The cncentratin f cnducting salts cannt be readily determined by measuring the specific gravity f the slutin because they transfrm with bath use and time. Peridically send a sample f the slutin t NB Technlgies fr analysis f cnducting salts cncentratin. Rev 2.0 / Page 3

4 MAINTENANCE Rutinely analyze the plating slutin fr gld cncentratin t determine the need fr replenishment r t verify the accuracy f a replenishment schedule based upn Ampere-minutes f use. NB Technlgies ffers bath analysis service and sample kits fr shipping. Gld cncentratin Actins n Au cncentratin accrding t analysis: At lwer actin, at lwest at the latest, add crrespndent amunt f Au t the bath At upper actin reduce adding f Au n Amin-basis At maximum upper stp adding f Au n Amin-basis Replenishment f Au accrding t analysis: 10ml Au 100 X per 1g f Au t be added Replenishment f Au n Amin basis: Beside analysis result, Au can be replenished n the basis f Amin plated. 15 liters bath: Every plated 60Amin replenish 75ml f Au100 X (equaling 7.5 g Au) Au 100 BRIGHTENER TH Actins n Au 100 Brightener TH accrding t analysis: At lwest add crrespndent amunt f Au 100 Brightener TH and increase adding f Au 100 Brightener TH n Amin-basis At lwer increase adding f Au 100 Brightener TH n Amin-basis At upper actin reduce adding f Au 100 Brightener TH n Amin-basis At maximum upper stp adding f Au 100 Brightener TH n Amin-basis Replenishment f Au 100 Brightener TH n the basis f time and/r Amin The replenishment need f Au 100 Brightener TH is influenced n the cnditins f xygen entrapping int the electrlyte. This is a value f experience and cnditins f individual tling, cnditin f flw and Amin plated. When flw is minr r turned ff fr a lnger perid, there is n need t replenish. Replenishment f Au 100 Brightener TH n mere time basis is nt recmmended in the initial phase. In rder t find ut the individual amunt f replenishment influenced by Amin and time, sample analysis crrelatin ver several weeks f peratin is needed. After gaining the replenishment crrelatin per week peratin, the replenishment can be perfrmed n Amin. The time plan fr analysis cntrl can be less tight. Replenishment f Au 100 Brightener TH n the basis f ptical inspectin. When the surface rughness is nt satisfactry, the smthness can be regained by adding Au 100 Brightener TH. This methd might be needed especially during the crrelatin finding phase. Prvided prerequisites: 1. The surface cnditin is nt caused by ther effects (impurities, particles, etc). 2. The Au 100 Brightener TH cncentratin is securely far frm the maximum upper. Add 20ml/l Au 100 Brightener TH, until surface gets rid f unsatisfactry rughness. Rev 2.0 / Page 4

5 Cntrl f density and replenishment f cnductin salt Density may be reduced by drag ut and fill up with DI-water. Density is t be measured in g/cm³ using a density meter with adequate measurement sensitivity. At 1,261g/cm³ the slutin may be needed t be dumped. Actins n density measurement results: Make sure Au cncentratin is within the specified range. At lwer actin, at lwest at the latest, add 5g/l Au 100 Cnditiner incrementally t avid vershting 1,261g/cm². Disslve at elevated temperatures (45-55 C). At upper actin intensify measurement cycles At maximum upper dilute slutin t ptimum level, analyze diluted slutin and replenish accrding analysis result ph cntrl and adjustment During peratin the ph tends t drp. ph MUST never drp lwer than 8, r the Au cmplex may fall ut. Prper peratin is prvided in the specified range nly. At ph ver 10, pht resist stability may be affected depending n the type f material. Actins n ph measurement results: Make sure t agitate prperly during adjustments: At lwer actin, at lwest at the latest, raise ph by adding 5 t 20% NaOH (100ml NaOH (5%) is cmmn t raise ph frm 9,2 t 9,35 in 45 liter bath) At maximum upper, lwer the ph by adding 5% sulphuric acid. This nrmally is nt needed r ccurs at new mixture nly. D nt use higher cncentratins t avid lcalised ph drp dwn lwer than ph 8 during additin. Stress measurement Stress can be evaluated by sheet film depsitin and measurement f the change f wafer bw. Usual stress level fr 7µm film plated at 1,5mA/cm²: -40MPa cmpressive Stress level tends t drp in tensile directin ver peratin time Actins n stress measurement results: Frm mechanical perspective the bath can be perated within in the maximum ranges. Still, reaching the ranges is a sign f pr cnditin f the bath, which gives mtivatin t set up a new bath. There are n replenishers t adjust stress specifically. At lwer and upper actin, check fr imprper cnditins f bath and tl At maximum and minimum actin, and after excluding abnrmal tl cnditins, cnsider t perfrm carbn filtering r t dump the slutin right away and reclaim the Au. Carbn filtering In rder t remve rganic cntaminatins as per analysis r by suspect, rganic cleaning and carbn filtering may be applied. After the prcedure, analysis and replenishment f the additiners is required. Regular carbn filtering is nt recmmended. Cntact NB Technlgies GmbH fr technical assistance. Impurities Intrductin f metallic impurities int the slutin shuld be prevented by prper rinsing f the parts t be plated. The NB SEMIPLATE AU 100 TH prcess is relative tlerant t lw levels f heavy metal cntaminants, as it will c-depsit these metals withut serius effect upn either the appearance r physical prperties f the depsit. Organic impurities may be dragged int the plating slutin frm a variety f surces and will usually result in a significant decrease in plating efficiency which will eventually lead t bath decmpsitin. Rev 2.0 / Page 5

6 SPECIFIC PROCEDURES Oxygen plasma befre plating chemical pre-treatment nt recmmended/nrmally nt needed Cleaning f all items with DI befre insertin in electrlyte Wetting f wafer surface with DI water befre insertin int bath (check fr wetting) CUSTOMER SUPPORT Further custmer supprt n the prcess with this prduct is available by cntacting NB Technlgies GmbH. BATH ANALYSIS SERVICE NB Technlgies supprts the bath analysis and prvides special shipping kits including shipping bx, sample bttles and labels. DATA LOGGING Keep a recrd f ampere-hurs f use t determine replenishment vlumes. Examples f prcess lg sheets are available by cntacting NB Technlgies GmbH. HANDLING AND SAFETY INSTRUCTIONS Fr detailed infrmatin cnsult the material safety data sheets fr this prduct. Please read material safety data sheets carefully befre using this prduct. DISCLAIMER All recmmendatins and suggestins in this bulletin cncerning the use f ur prducts are based upn tests and data believed t be reliable. Since the actual use by thers is beynd ur cntrl, n guarantee expressed r implied, is made by NB Technlgies GmbH, its subsidiaries f distributrs, as t the effects f such use r results t be btained, nr is any infrmatin t be cnstrued as a recmmendatin t infringe any patent. ADDRESS NB Technlgies GmbH Fahrenheitstr Bremen Tel Fax inf@nb-technlgies.de Rev 2.0 / Page 6