The significance of silicon wafer heat treatment
The significance of silicon wafer heat treatmentHeat treatment temperature requirements: 650 + 5 c;The purpose of heat treatment is to restore the true resistivity of Czochralski silicon wafers;
Heat treatment at 650 DEG C, under the condition of rapid cooling (that is, rapidly over the temperature of 450 DEG C), the thermal donor can be eliminated. That is, we can observe that the resistivity of N sample is high, and the resistivity of P sample is low.Precipitation: 800-1200 DEG C, on behalf of temperature 1050 degrees CHeat treatment at 1050 DEG C, will bring oxygen precipitation, and the formation of defects caused by precipitation defects.Restore: > 1200
2, heat treatment of several temperature interval concept:Thermal donor: 350-550 degrees Celsius, 450 degrees Celsius450 C after heat treatment (or equivalent effect, such as the cooling of a single crystal in a furnace), the resistivity of the N type sample can be decreased and the resistivity of the P type sample is increased, as is the introduction of a certain number of donor phenomena. This is due to the temperature of the dissolved oxygen atoms in the formation of complex (SiO4) caused by the thermal donor, the resistivity of silicon and oxygen content of the four side is inversely proportional to.New donor: 550-800 DEG C, on behalf of the temperature of 650 degrees Celsius
What will the resistivity change after heat treatmentBecause oxygen is the introduction of single crystal silicon at about 1400 DEG C, so the manufacturing process in general device temperature range (less than 1200 C), with the gap state of oxygen is in a saturated state, thermal cycling in the process of oxygen impurity in these devices due to the lower solid solubility will produce oxygen precipitation. Generally speaking, the higher the concentration of oxygen, the easier the oxygen precipitation is, the more oxygen precipitation is formed. On the contrary, the less oxygen precipitation. Especially when the oxygen concentration is less than a certain value (5 x 1017 / cm 3), the formation of oxygen precipitates is hardly observed.
