A method for forming a silicon germanium source/drain structure

Abstract

The invention discloses a forming method of a silicon-germanium source / drain structure. In the forming method of the silicon-germanium source / drain structure, a buffering structure (namely two transition layers or one transition layer) is increased between a body layer and an overlaying layer, the content of germanium can be gradually reduced, and therefore lattice mismatch is greatly reduced; meanwhile the temperature can be gradually changed, heat mismatch is avoided, therefore pressure stress of a silicon-germanium layer can be guaranteed, and performance of a device can be promoted.

Description

technical field [0001] The invention relates to the field of integrated circuit manufacturing, in particular to a method for forming a silicon germanium source / drain structure. Background technique [0002] In the advanced complementary metal oxide semiconductor (CMOS) industry, in order to improve the performance of PMOS, the material usually used in the source / drain region is silicon germanium (SiGe), and the source / drain region mainly includes three layers: the seed layer (seed) , bulk and cap. [0003] Such as Figure 1a As shown, it is a schematic diagram of a silicon germanium source / drain structure formed by an existing process, a gate structure 2 and an isolation structure 3 are formed on a substrate 1, and source / drain regions 4 are formed on both sides of the gate structure 2, specifically , the source / drain region 4 includes a seed layer 5 , a bulk layer 6 and an upper cladding layer 7 . The bulk layer 6 is usually a silicon germanium (boron) layer, and the uppe...

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Problems solved by technology

[0004] The object of the present invention is to provide a method for forming a silicon germanium source / drain structure, so as to solve the problem of poor device performance caused by lattice mismatch and / or thermal mismatch in the prior art

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