What is Silicon?

Silicon (Si) has many uses within the field of semiconductors. Elemental silicon is the main component of most devices, most importantly integrated circuits or microchips.

Silicon is widely used in semiconductors because it remains a semiconductor at higher temperatures than other materials and because its native oxide is easily grown and forms a better semiconductor/dielectric interface than almost all other material combinations.

Doping Silicon with other elements adjusts its electrical response by controlling the number and charge of current carriers. Such control is necessary for transistors, solar cells, microprocessors, semiconductor detectors and other semiconductor devices which are used in electronics and other high-tech applications.

Increasingly, R&D and production sites are realising the benefit of using Logietch precision cutting, lapping and polishing machines for accurate silicon processing. For example, in wafer and chip manufacturing of IR and polymer waveguides, the exacting design and manufacture of standard Logitech equipment ensures the customer will achieve the highest quality results.

Silicon Wafer Processing Applications

 

Wafer and Substrate Preparation

For the production of thin or ultra-thin device wafers, Logitech offers unique assistance with the problems of wafer lapping and polishing, backthinning and achieving geometric control, in addition to the integration of these processes into the customer's total fabrication programme.

The process technology involved in this application wil require one or more of the following options in a suitable combination and sequence :

• Slicing of wafers from the crystal boule
• Low, medium or high precision bonding of wafer to support disc
• Jig-controlled lapping and polishing using single or multiple-workstation machines

Quantity

Machine	Sample	Timer per 100 wafers	Stock removal rate	Sample output
APD1Saw	2" ø boule	6 hrs	-	800 wafers
APD2 Saw	3" ø boule	7.2 hrs	-	600 wafers
PM5 (Lapping)	4" ø boule	-	5 microns	60 wafers
PM5 (Lapping)	2" ø boule	-	8 microns	100 wafers
PM5 (Polishing)	4" ø boule	Ra to <100nm	Ra to <100nm	40 wafers
PM5 (Polishing)	2" ø boule	Ra to <100nm	Ra to <100nm	40 wafers
LA50 Auto (lapping) / 3 jigs	4" ø boule	-	5 microns	144 wafers
LA50 Auto (lapping) / 3 jigs	2" ø boule	-	8 microns	204 wafers
LA50 Auto (polishing)	4" ø boule	Ra to <100nm	Ra to <100nm	100 wafers
LA50 Auto (polishing)	2" ø boule	Ra to <100nm	Ra to <100nm	180 wafers

 

Typical Silicon polishing conditions

Scratch hardness (Mohn’s scale):	3
Polisher:	Wax
Abrasive:	Linde A
Lubricant:	10% Chromic Acid
Load (g cm-2):	60 - 80
Machine:	Logitech PM5AC / LP50C
Fixture:	Logitech PP5/6GT
Typical Silicon Lapping & Polishing Results
Flatness:	5 Fringes
Surface Finish:	Ra 3-4nm
Thickness Control	+/- 2 microns down to below 100 microns
Parallelism	+/- 2 microns