About The Problems Encountered In Magnetron Sputtering, Very Comprehensive!

- Jan 18, 2019-

About the problems encountered in magnetron sputtering, very comprehensive!

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01

1. Magnetron sputtering & glow discharge problem of magnetic target

a. Enhance magnetic field B.n 300-700gs

b. Reduce target material thickness 2-3mm

c. Increase working pressure

d. Remove the dirt of target surface

 

2. Reduce the roughness of surface

a. heat treatment

 b. control process parameters

 c. mechanical polishing

d. chemical polishing

e. electrochemical polishing

f. the bottom layer plating by liquid phase

g. Spraying organic bottom layer

 

3. Film adhesion

a. cleaning

 b. drying

c. plasma cleaning

d. transition layer

 

4. Sputtering deposition speed is slow

a. Reactive sputtering: finding the critical point of the hysteresis curve, will rise the deposition rate and improve the film quality;

b. RF sputtering: increased power and reduced air pressure (e.g. 7.5mt)

 

5. The introduction of acetylene may lead to uneven phenomena in the reaction sputtering process, resulting in differences in the quality of the deposited film on the substrate, thus reflecting (regular) color stripes.

 

6. Instructions for long-time sputtering

 

a. Cooling system

 b. Shield

 c. Power supply arc extinguishing function

 d. High temperature resistance of lining plate

 

7. Influence of magnetron sputtering parameters

 

a. other things being equal, the influence of power density and time on film thickness is approximately proportional. The increase of power is beneficial to increase the density and crystallization of the film. The increase or decrease of time affects the temperature rise of the substrate and the thickness of the film, and indirectly affects the crystallinity

b. Uniformity: optical uniformity, electrical uniformity and film thickness uniformity.

c. Spectrometer, four-probe, film thickness tester.

d. DC: stable potential, conventional conductive target materials such as metal and ITO, stable deposition rate high

 e. RF: high-frequency oscillation, commonly used in 13.56mhz, used for insulation (SiO2,AL2O3), semiconductor, metal materials, dense film, low deposition rate.

 

8. Radiation from a magnetron power supply

 

a. power radiation exists, especially RF power

 b. suggested that chooses import power (AE etc.), Domestic RF power reflected power 2%, import power can be controlled under 1 w .

c. power match box and cathode between attachment shall be shielded

d. maximum radiation leak power matching process, because of the high reflective power match not ok ,means that the higher reflection

e. for prepare pregnancy and pregnancy, stay away from radio frequency

 

9. Detection of black spots in oxide film due to hypoxia

 

a. The RF sputtering oxides are generally excellent, and some oxygen elements are missing in the film layer;

b. 10% oxygen can be flushed to improve

c. Observe the etched runway. If the etched runway is as dark as the color of the body, this problem can be eliminated. If the etched runway is much darker than the body, it is  the lack of oxygen.

 

10. The sputtering yield of Al was lower than Cu and Gr

 

A. sputtering yield affecting factors: the incident ion energy & can escape the atomic bonding

b. sputtering: the nature of the impact & escape

c. impact: the greater the momentum - the higher the yield, industry generally use Ar (cost & sputtering yield consideration)

d. escape: small Al atoms and outer three electrons, adhesion is strong, low sputtering yield

e. different sputtering yield a regular feature in the periodic table

 

11. Maximum power density of magnetron sputtering dc target

a. influence factors: cooling, target material, the structure of target

 b. example: ceramic/Si 5-8 w/c metal target 20-40 w/c

 

12. Plastic coating

A. existing problems

a. large water absorption, large air release

b. non-polar, big difference with film thermal expansion coefficient

 c. large roughness and poor heat resistance

B. Cautions

a.Substrate selection: low roughness, less air release

b. Process vacuum increased, process temperature decreased

c. Surface pretreatment, coating primer such as UV organic coating, plasma cleaning

Add transition layer

 

13. Small particles on the surface of dc sputtering

a. cleaning problem

b. cavity dust

c. target impurities

d. power supply mismatch, starting ARC

e. may be incomplete oxidation for reactive sputtering

 

14. Film thickness measurement

 

a. Ball mill

b. Step

c. Metallographic microscope cross section

d. SEM

 e. xry nondestructive thickness gauge

 

15. Target poisoning

 

A. The main reason for target poisoning is that the synthesis speed of the medium is greater than the sputtering yield (too much oxygen reaction gas passes through), resulting in the loss of the conductive ability of the conductor target. Only by increasing the breakdown voltage, the spark can be generated. Phenomenon: the target voltage cannot reach normal for a long time, and the sputtering target is always in low voltage operation state, accompanied by arc discharge; The target surface appears white fixtures or dense needle gray discharge traces

 

B. To completely eliminate target poisoning, intermediate frequency power supply or rf power supply must be used instead of dc power supply; Methods such as reducing the flux of reactive gas, increasing the sputtering power, cleaning the pollutants (especially oil stains) on the target material, and selecting the dustproof arc extinguishing mask with good vacuum performance can effectively prevent the occurrence of target poisoning. The magnet soaked in cooling water inside the target has stains. As long as the magnetic field strength is enough and the cooling effect is good, it has little influence on the target

 

C. The stain has little effect ~ the ignition is caused by the insulating part, usually local poisoning or stolen goods. Sputtering target is poisoned because the power density is too low and the excess reactive gas cannot be vaporized (or sputtering) in time, which will leave the surface of the target and reduce the electrical conductivity, thus entering the toxic state. Light can not glow, heavy scrapped power supply.

 

16. Common targets

 MF cylinder target11

Metal target: Ni, Ti, Zn, Cr, Mg, Nb, Sn,Al,In,Fe,ZrAl,TiAl,Zr,AlSi,Si,Cu,Ta,Ge,

Ag,Co,Au,Gd,La,Y,Ce,W,Stainless Steel,NiCr,Hf,Mo,FeNi,etc.

 

Ceramic target: ITO target, ferric oxide, magnesium oxide target, target, target, silicon carbide silicon nitride titanium nitride target target target, target, zinc sulfide, zinc oxide, chromium oxide and silicon dioxide target target, target a silicon oxide, cerium oxide, zirconium dioxide target, niobium pentoxide target target, target, titanium dioxide, zirconium dioxide, hafnium target, target, titanium diboride diboride zirconium target, target, tungsten trioxide target tantalum pentoxide 3 oxidation 2 aluminium, niobium pentoxide target target, target, yttrium fluoride, magnesium fluoride, zinc selenide target, target, aluminum nitride silicon nitride target, target, boron nitride titanium nitride target, silicon carbide target, target, titanium acid lithium niobate praseodymium target lanthanum titanate, barium titanate target, target, nickel oxide target, etc.