Device and method for monitoring deposition thickness of polysilicon furnace tube

Abstract

The invention provides a polycrystalline silicon furnace tube deposited film thickness monitoring device and method. A top control wafer and a middle control wafer can be replaced with control wafers of which the surfaces are subjected to annealing treatment in an existing three control wafer monitoring mode, and the problem that film thicknesses of wafer surfaces of a product are inconsistent can be avoided; meanwhile, the authenticity and stability of control wafer monitoring data are guaranteed, and the product yield is increased.

Description

technical field [0001] The invention relates to the field of semiconductor manufacturing, in particular to a device and method for monitoring the deposition thickness of a polysilicon furnace tube. Background technique [0002] As an important semiconductor thin film material, polysilicon thin film has already attracted people's attention, and it has been widely used in the manufacture of integrated circuits and various electronic devices. , is an ideal structural layer material, and is especially widely used as the basic structural material in microelectromechanical systems (MEMS). [0003] In the prior art, the polysilicon deposition in the semiconductor structure is usually carried out using a vertical furnace tube (Poly Furnace) for low-pressure chemical vapor deposition, and the furnace tube process is different from other monolithic operations in that it is a batch operation, that is, There are multiple batches of product wafers operating in the furnace tube at the sa...

AI Technical Summary

Problems solved by technology

[0004] Due to the presence of a loading effect in the polysilicon furnace tube process, the polysilicon thickness formed on the surface of the product wafer 20 immediately below the top control sheet TOPC / W and the product wafer 20 immediately below the middle control sheet CTR C / W The thickness of polysilicon on the surface of the product wafer is lower than that of other positions. The possible reason for this difference in thickness is the absorption of heat by the back of the top control chip TOP C / W and the back of the middle control chip CTR C / W compared to its upper surface. There is a difference with the reflection, so that the reaction gas concentration on the surface of the product wafer 20 immediately below the top control sheet TOP C / W and the product wafer 20 immediately below the middle control sheet CTR C / W is different from other positions, The degree of reaction is different, which eventually leads to a large difference in polysilicon film thickness between the product wafers in the two places and the product wafers in the same chamber, resulting in abnormal monitoring data

When subsequent polysilicon etching is performed on the product wafer on the wafer boat, the dryness of the polysilicon film on the surface of the product wafer 20 immediately below the top control sheet TOP C / W and the product wafer 20 immediately below the middle control sheet CTR C / W The dry etching rate of the polysilicon film on the surface of the wafer at other positions is also faster than that of the dry etching rate, which is easy to form such as Figure 1B The pit defects (pits) shown, make the yield of the product drop

[0005] Therefore, there is a need for a polysilicon furnace tube deposition film thickness monitoring device and method, which can avoid the problem of inconsistent film thickness on the surface of the product wafer, and at the same time ensure the authenticity and stability of the monitoring data of the control film, and improve the product yield rate.

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