Description

Silicon Carbide Boat

We use S-SiC for making wafer boat. Here are the Physical Properties of the S-SiC .

ITEM	UNIT	S-SiC
Density	g/cm³	3.10
Porosity	%	3
Flexural Strength	MPa	450 (20^oC) 450 (1200 ^oC)
Young’s Modulus	GPa	420 (20^oC) 420 (1200 ^oC)
Fracture Toughness	MPa. m^1/2	4
Hardness	Kgf/mm²	2,300
Thermal Shock Resistance	DT^oC	450
Thermal Conductivity	W/m. ^oK	126
Electrical Resistivity	Ohm.cm	10^5
Thermal Expansion	10^-6/^oK	4
Specific Heat	(J/Kg. ^oK )	700
Max. Serve Temp.	o_C	1,700

Applications:

Wafer carrier for semiconductor and solar cell industries

Product Features

High temperature and corrosion resistant, improving wafer quality and productivity

The practice and difference of various SiC crystal boats

A) Graphite boat coated with CVD-SiC film

Graphite is easily to be machined in precision to meet your requirement even in one piece and low cost. But after CVD-SiC coating, the thickness of SiC film at all area of boat is not easily to be controlled. Due to the CTE (coefficient of thermal expansion) mismatch between graphite body and SiC film, the SiC film usually peels off after several runs. The SiC film is also easily broken due to collision in automation transportation. Once SiC film is peeling off, graphite will expose to the environment causing unexpected results. This kind of graphite boat coated with CVD-SiC film is the cheapest and has the shortest life, about 1 year.
B) Recrystallized SiC boat coated with CVD-SiC film

Recrystallized SiC boat is usually preformed and sintered in several unit parts, after machined separately then joined with Si paste at high temperature, furthermore CVD coated with SiC film. Because recrystallized SiC is porous, it can be joined (glued) by Si paste at high temperature. If it did not CVD coated with SiC film, the porous recrystallized SiC would cause particle issue in process. Therefore, the cost of recrystallized SiC coated with CVD-SiC film is very expensive. Besides, the join area (Si paste) can’t withstand as high temperature as SiC material. Further, once the coated SiC film is peeled off usually by collision, the porous recrystallized SiC would cause particle issue in process. This kind of recrystallized SiC boat coated with CVD-SiC film has the longest process (preformed, sintered and machined in several unit parts, joined all unit parts with Si paste at high temperature, then CVD-SiC coating) and the highest cost. Life time is around 2~3 years.
C) SiC boat without CVD coating in one piece
There are two kinds of SiC materials, presureless sintered SiC (S-SiC) and reaction bonded SiC (RB-SC), also called silicon infiltrated SiC (Si-SiC) . It is not easy to form the SSiC boat in near net shape and SSiC is very hard and not easily to be machined, which cause extremely high cost to be machined in your case. Although RB-SC is a little easier than S-SiC to be formed in near net shape, RBSC is still very hard and not easily to be machined, which cause extremely high cost, too. On the hand, RBSC has 10~15% free Si, which can’t withstand as high temperature as SSiC material. And, free Si would be easily etched by HF acid causing particle issue subsequently.
D) Our SiC assembly boat (without CVD coating)

The material of our SiC boat is pressureless sintered SiC (S-SiC) with 99.675% purity . We form and machine the unit parts separately, then join them together by S-SiC screw and fix by S-SiC pin. We caculate the weight of your total loading and put it into consideration. The loading capability will be much higher than your needs. The strength of our SiC boat will not be an issue. Besides, the SSiC has not film peeling off causing particle issue and sustainable at critical environments, for example, high temperature, corrosive and HF acid. We guarantee the life time of our SiC assembly boat having more than 5 years. Thus, we believe that our SiC assembly boat is the best cost effective in all kinds of SiC boat.

SiC Product Features

High temperature and corrosion resistant, improving wafer quality and productivity

SiC refers to silicon carbide. Silicon carbide (SiC) is made of quartz sand, coke and other raw materials through the high temperature furnace melting. The current industrial production of silicon carbide has two kinds, black silicon carbide and green silicon carbide. Both are hexagonal crystal, the specific gravity of 3.21g / cm3, micro hardness of 2840 ~ 3320kg / mm².

At least 70 kinds of crystalline silicon carbide, due to its low gravity 3.21g/cm3 and high temperature strength, it is suitable for bearings or high temperature furnace raw materials. at any pressure can not be reached, and have a considerable low chemical activity.

At the same time, many people have tried to replace silicon with silicon carbide due to their high thermal conductivity, high crush electric field strength and high maximum current density. Recently, in the application of semiconductor high power components. In fact, the silicon carbide substrate in thermal conductivity, more than 10 times higher than the sapphire substrate, so the use of silicon carbide substrate LED components, with good conductivity and thermal conductivity, relatively conducive to the production of high-power LED

Material Comparison Chart:

Nature	density(g/㎝3 )	density(g/㎝3 )	(10-6 / ℃)	(Kgf/㎜2 )	(J/㎏*°K)	(GPa)	(MPa)	(MPa)	(MPa)	(MPa*m0.5 )	(Poisson’s ratio)	(℃)
Al2-O3	3.9	3.9	8	1600	880	370	262	2600	380	3.6	0.26	2053
ZrO2	6	6	10.1	1400	400	200	700	1850	690	9.5	0.23	2700
SiC	3.2	3.2	4	2300	700	410	400	3900	550	4.6	0.19	2700
Si3 N4	3.3	3.3	2.3	1500	700	310	524	2500	780	7.7	0.24	1900
Cellon Sialon	3.2	3.2	3	1600	620	300	450	3500	600	6.5	0.23	1900
WC	15	15	6	1600	390	700	896	6100	550	25	0.18	2870
Glass	2.5	2.5	0.5	1000	740	70	–	1100	69	1	0.2	2200
BN	2	2	2	220	1850	62	41	143	73	–	0.13	2600
AlN	3.2	3.2	4.4	1200	730	340	400	2070	350	2.6	0.25	2400
B4 C	2.5	2.5	5.6	3200	930	450	350	2800	400	3	0.15	2450
Steel	7.8	7.8	13.6	126	448	200	520	–	–	14	0.3	1450

Relatively high thermal conductivity of the substrate table:

Substrate material	FR4	MCPCB	LTCC	Al2-O3	SiC	AlN
(W/m*°K)	0.7~1.2	2~6	8~15	20~28	120~140	140~180
Insulativity(Ω×㎝)	1014	108	1013	1015	108	1011
(0.25cm2 ) (W)	<0.2	0.5~1	1~1.5	2~3	3~15	15~20
Board size	To large-scale	To large-scale	No more 6″×6″	No more 6″×6″	No more 6″×6″	No more 6″×6