Electrostatic chuck for accelerating wafer etching uniformity

Abstract

The related static chuck benefit to evenness of wafer etching comprises a static chuck with diameter of top surface larger than the target wafer, and a focus ring matched round the chuck with an integrated convex ring with lower surface matched to the chuck top surface. The benefits of this invention comprises: effective temperature control to improve the temperature controllability of wafer edge, more stability on impedance between the chuck and the wafer, and more evenness on dc bias formed by RF to produce more even plasma.

Description

technical field [0001] The invention relates to the technical field of microelectronics, in particular to an electrostatic chuck for promoting uniform wafer etching by controlling the temperature of the wafer edge region and improving the radio frequency RF at the wafer edge. Background technique [0002] During the whole process of etching, the wafer is adsorbed and fixed by the electrostatic chuck (ESC) in the lower electrode system, and the radio frequency RF is passed into the electrostatic chuck, so that the radio frequency RF will form a DC bias (DC bias voltage) on the wafer. ). This facilitates the etching reaction of the plasma to the wafer. At the same time, the electrostatic chuck will control the temperature of the wafer to promote the uniformity of wafer etching. The upper and lower parts of the electrostatic chuck are insulating layers, and the middle part is provided with an electrode layer. When a DC voltage is applied to the electrode layer, different cha...

AI Technical Summary

Problems solved by technology

During the etching reaction process, the electrostatic chuck of the traditional structure has adverse effects on the wafer in two aspects:

[0004] (1) The edge area of ​​the electrostatic chuck 1 is in contact with the convex ring of the focus ring 4, which affects the heat conduction of the electrostatic chuck to the edge of the wafer, makes it difficult to control the temperature of the edge of the wafer, and indirectly affects the etching rate of the plasma to the wafer

[0005] (2) Due to the formation of steps in the area a at the edge of the electrostatic chuck, the capacitance value between the electrostatic chuck and the edge area of ​​the wafer is reduced relative to the part where the wafer is in full contact with the electrostatic chuck, increasing the impedance

In this way, the energy coupled to the edge of the wafer by radio frequency RF is reduced compared with the energy coupled to the central part, resulting in the inhomogeneity of plasma etching

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