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CST Clean Surface Technology Co.

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Production ProcessCST HT Phase Shift Blanks
CST Fringr Small CoatingZF11 : For large high definition photomask
HT type FHT typeTop type/bottom type half-tone mask




Production Process

Polished quartz or soda-lime glass is used for making mask blanks. Chrome and Chromic oxide are coated on the substrate.
This bilayer is formed by sputter device. We'll show you a general process below...

[Incoming inspection]

Checking scratch, chip and damege the plate has

[Sputtering]

Feature of CST film composition : CrO+Cr+CrO

 
 

[Pre-rinse with cleaning device]

Place substrate on a holder and rinse by dipping. Acid, alkaline, US treatment is done.
Occasionally UV treatment is necessary for the better wettability.

[Special inspection of film]

Measurement of reflectiveness, Optical density and film thickness

 
 


[Inspection after sputtering]

Check particle, dirt and PH with Halogen-lamp

 
 

[Prodction rinse]

After rinse through US treatment by DI water, lift to dry.

[PR coating]

We coat all sizes of substrate by spin method

[Prebaking]

Prebaking of PR surface by Hotplate

 
 

[Substrate inspection]

Checking defects using Halogen-lamp powered 600,000 lxs

[Final inspection]

 
 

[Load to sputter-machine]

Plate is stored in case, packaged, then shipped



CST Fringr Small Coating

This data shows a uniformity of PR surface after FS (Fringe Small) coating a GRX-M220 on a 700×800 size substrate targeting centered on 765nm, which performed 17nm range. Widely expanded patterning area compared to FF product, resulted in about 7mm as a fringe part. Now it covers size up to 800×960 as our product and developing 1220×1400 for use.




CST HT Phase Shift Blanks

CST has achieved success in an angle of inclination of the pattern cross-section forming right-angle with PS2013 madel, insted of sloping. Performing phase control for your own wavelength convenience, and applicable to adjust transmission volume with membrane composition.

[PS2013 model pattern cross-section(conpare to conventional product)]


[PS2013 model Thickness 1123Å Transmission and phase characteristics]

PS2013 365nm405nm436nm
Thickness 1123ÅTransmission5.0%8.6%12.0%
Phase Shift187.2°170.6°160.7°


ZF11 : For large high definition photomask

[Etching character of ZF11]


[Time of additional etching and loss volume of pattern-width]


[SEM photo of ZF11]


[Flatness change with CS8(1220×1400×13t)]
Flatness data below was all measured by the backside of a plate. Concave and convex is upside down when measured by front side.


[Face difference]
Plate will be returned to their nomal condition after removal of film.

Flatness change with ZF11(1220×1400×13t)]


[Flatness change with 800×920×8t]
Flatness data below is observed from film surface
ZF11


CS8



HT type and FHT type

HT type based on Chromic oxide is preferable for high transmission purpose. We actually coat 30~70percent transmission as our performance.
FHT type based on Chrome, smaller wavelength-dependent is preferable for lower transmission purposes.
It has a transmission performance of 10~40 percent.




Top type / Bottom type half-tone mask

Process of top type half-tone mask
The now leading half-tone mask is produced by coating with half-tone film on the once patterned mask. This type(half-tone film lies on Cr film) is called a top type half-tone mask.



Exposure of half-tone mask


Half-tone blanks
Half-tone blanks consists of 3 layers: half-tone film (on the substrate), etching-stopper film(in the middle) and Cr film(on the top) This type is called a bottom type half-tone mask. Bottom type half-tone film is considered to be difficult to administer wet treatment alone.
CST is under development of half-tone blanks that can receive wet treatment.





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