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The practice and difference of various SiC crystal boats, share

A) Graphite boat coated with CVD-SiC film
     Graphite is easy to process, and it can be processed into a single piece

     crystal boat from a block through various precision processing.
     Since graphite is a porous substance, its surface must be coated with a

     layer of CVD-SiC thin film to avoid direct exposure of graphite surface

     to various semiconductor processes to cause fine particles (particle)

     problem.
     But after the CVD-SiC coating, the thickness of the SiC film in all areas

     of the wafer surface is Not easy to control.
     Due to the mismatch of CTE (coefficient of thermal expansion) between

     graphite body and SiC film, It is easy to peel off after using it several

     times. Furthermore, due to The SiC film is also easily broken. Once the

     SiC film is peeled off, graphite will be exposed to the environment,
     After the corrosive gas or liquid enters the porous graphite body, it is

     not easy to remove, resulting in high Unexpected results from fine

     particles occur during the warming process.
     The graphite boat coated with CVD-SiC film is the cheapest and has the

     shortest life, about 1 year.

 

B) Recrystallized SiC wafer boat coated with CVD-SiC film
     Recrystallized SiC boat is usually formed by sintering several unit parts in

     advance, and then adding them separately.
     After that, the unit parts are joined with Si paste at high temperature, and

     then integrated into a wafer boat. CVD coated SiC film. Because

     recrystallized SiC is porous, it can be used at high temperatures Si paste

     bonding (glue). Porous recrystallized SiC without CVD-coated SiC film It

     can cause fine particle problems in various semiconductor processes.
     Therefore, the cost of recrystallized SiC coated with a CVD-SiC film is very

     expensive. In addition, The Si paste in the junction region cannot withstand

     the same high temperature as the SiC material. In addition, once the boat
     The collision caused the coated SiC film to peel off, and the porous

     recrystallized SiC will Particle problems are caused during the 

     manufacturing process. Recrystallized SiC coated with CVD-SiC film, The

     boat manufacturing process is the longest (several unit parts are pre-

     formed, sintered and machined, At high temperature, all unit parts are

     connected with Si paste, and then coated with CVD-SiC) and cost highest.

     Recrystallized SiC and CVD-SiC films are thinner than those of graphite-

     coated CVD-SiC films  There is no CTE mismatch in the membrane.

     However, CVD-SiC films with a thickness of about 100um,The coated SiC

     film is peeled off due to collision, and its service life cannot be very long,

     about 2~3years.

 

C) One-piece SiC wafer boat without CVD coating
     For wafer boats without a CVD coating, the prerequisite is that the surface

     must be a dense material. Compactness, There are two kinds of SiC

     materials, pressureless sintered SiC (SSiC) and reaction sintered SiC

     (RBSC, Also known as silicon infiltrated SiC (SiSiC)). Both pressureless

     sintering (SSiC) and reactive sintering SiC (RBSC) materials cannot be

     united by fusing each unit component like quartz material. Of course 

     However, it is not acceptable to shape the SiC from powder and sinter it

     into a one-piece wafer boat. Easy, and SiC is very hard and not easy to

     process, which will result in a one-piece SiC wafer boat.
     Labor costs are extremely high. Although RBSC is slightly easier to form a

     near-net shape than SSiC, RBSC still However, it is very hard and not easy

     to process, which also results in extremely high costs. On the other hand,

     RBSC contains With 10-15% free Si, it cannot withstand the same high

     temperature as SSiC materials, and free Si is easily etched by HF acid,

     causing fine particle problems.

D) Kallex SiC combined wafer boat (without CVD coating)
     The material of our SiC wafer boat is pressureless sintered SiC (SSiC) with a

     purity of  99.675%. We shape, sinter and grind each unit component, then

     use SSiC screws and bolts Combine them together and secure with SSiC

     pins. We calculate the weight of the total load and Taking into account, its

     loading capacity will be much higher than your needs. The strength of our

     SiC wafer boat is not a problem.
     In addition, pressureless sintered SSiC does not have the problem of

     particles caused by CVD thin film peeling, and is severe Environments such

     as high temperatures, corrosives and HF acids can withstand long-term

     challenges.

     We guarantee us The life of the SiC combined wafer boat is more than 5

     years. Therefore, compared to various SiC wafer boats, We believe that our

     SiC combined wafer boat is the most cost-effective among them.