SOI/Silicon on Insulator Crystal Wafer technology uses a composite substrate: active silicon layer-insulator-bulk silicon (handle layer). In consequence, we improve performance and also reduce parasitic capacitance. The insulator can be silicon dioxide or sapphire (in the case of using sapphire technique is called SOS). Its choice depends on the application. Therefore, we use sapphire in high-performance radio frequency (RF) and silicon dioxide in microelectronics systems.
Basically we can produce SOI wafer based on the following methods:
– Wafer Bonding – one of the most popular method.
- First of all bonded SOI production process begins with oxidation of the donor wafers in a vertical furnace. The thermal oxide layer will ultimately form the buried oxide or box layer of the finished SOI wafer. Following oxidation the donor wafers are implanted with ions and a standard batch ion implantation system. The ions penetrate through the thermal oxide layer and come to rest in the subsurface region of the underlying donor wafer. The implantation energy determines the depth of this layer below the surface. Higher implantation energies enable deeper penetration of the implanted ions. This layer forms the fracture plane which separates the top silicon and box layers from the donor wafer. It allows the transfer to the handle wafer. In consequence, the energy of the implanted ions determines the thickness of the top silicon layer.
- Secondly, after implantation we can bound the donor wafer to the handle wafer. Just prior to bonding, we meticulously cleane the donor and handle wafers to remove contaminants. These particles could interfere with the bonding process resulting in bonding voids. The first step in the bonding process is to expose the surfaces of the donor and handle wafers to a glow discharge plasma process. This process chemically activates the surfaces to produce a high initial bond strength. We rince the wafer surfaces in deionized water and spun drawing.
- Then, we bring into contact the donor and handle wafer surfaces. Next step is to apply a gentle compressive force at one edge of the way prepare. This initiates a bond wave that travels across the entire bod interface area bonding both wafers together. The bonded pair is given a treatment to further increase the bond strength. After that, we subject it to the mechanical cleaving process. We initiate a small fracture at the edge of the bonded pair as we are gently pulling the donor and handle wafers apart. The fracture jumps into the implanted layer and then propagates across the entire donor wafer.
- The handle wafer with the transferred oxide and silicon layers becomes the SOI wafer. We can repolish and recycle the remaining donor wafer to make additional SOI wafers. Then we give the Cleaved SOI wafer a high temperature and produce a high-quality bond interface. After this step the SOI wafer is ready for the EPI smoothing process.
– Separation by Implantation of Oxygen (SIMOX)– technology bases on the implantation oxygen ion beams. We transforme them into silicon dioxide in the process of annealing at an elevated temperature. It is forming the appropriate substrate.
– Seed Method – the upper silicon layer is growing directly on the insulator. In order to achieve adequate growth of the layer, the insulator should be appropriately treated, among other things, through chemical modification of the material.
As a result these methods allow to achieve a wafer substrate of perfectly uniform thickness and low defect concentration.
|Wafer diameter||2”,3ʺ, 4ʺ,6ʺ,8ʺ|
|Wafer thickness||2µm – 300µm|
|Thickness tolerance||+/- 5%|
|Surface finishing||double/single sided polishing|
|Crystal orientation||(100) (111) (110)…|
|Handle/Device Type||N-type, P-type or undoped|
|Handle resistivity||0.001 – 10000 Ohm-cm|
|Device resistivity||0.0025 – 150 Ohm-cm|
Also small quantities or individually packed wafers are available.
Should you need any further information or you are unable to find the wafer specification you require, please do not hesitate to contact us: [email protected] or TOLL FREE in Spain (+34) 900 838 909, Portugal (+351) 800 180 183 or France +33 805 080 082.