JPS624316A - Annealing of semiconductor device - Google Patents

Abstract

PURPOSE:To provide an annealing method which does not have influence upon the previously formed wiring s by a method wherein light which has energy smaller than the energy of a forbiddedn band of a semiconductor is applied to the back plane of the semiconductor and absorbed by a defective part and thermal annealing is carried out. CONSTITUTION:Infrared rays, which have smaller energy then the energy of a forbidden band of silicon, are applied to the surface 1a opposite to the oxide film 8 side of a semiconductor substrate 1. As a result, the infrared rays transmit through the silicon substrate 1, an epitaxial growth layer 2, a drain region 3 and a source region 4, and are absorbed to the boundary between the layer 2 or regions 3 and 4 and the oxide film 8. Therefore, heat is generated at the parts where the infrared rays are absorbed and the crystal defect parts of silicon at the boundary are efficiently heated and annealed so that the defects are removed. In such process, aluminum wirings 5 and 6 and the oxide film 8 are not influenced at all.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an annealing method for removing crystal defects generated on one surface of a semiconductor.

[Prior art]

During the manufacturing of MOS type semiconductor devices, silicon (
Si) and silicon oxide (Si
Crystal defects are induced in the silicon crystal at the interface with Ox) by irradiation with ions, electrons, X-rays, γ-rays, etc.
This often impairs device characteristics.

Therefore, conventionally, in order to remove these defects, a thermal annealing treatment is performed to apply heat to the defective portion, but this is usually performed at a temperature of approximately TOO° C. or higher. However, after the aluminum wiring, it is impossible to raise the temperature above 570° C. due to the relationship with the melting point of aluminum, and a low-temperature treatment has been desired.

For this purpose, it has been proposed to irradiate infrared rays from the outside of the silicon oxide film to anneal it in a short period of time. There were drawbacks such as being thin, and (1) infrared rays do not pass through the underside of the metal wiring, making it ineffective for that area.

[Purpose of the invention]

The present invention has been made in view of these points, and its purpose is to provide an annealing method that is not affected by the oxide film or the aluminum wiring that has already been wired.

[Structure of the Invention] For this purpose, in the present invention, in an annealing method for removing crystal defects on one surface of a semiconductor, light having an energy smaller than the forbidden band width of the semiconductor is directed to the opposite side of the surface of the semiconductor. It is irradiated from the side surface, and is transmitted without being absorbed by the semiconductor, and is absorbed by the defective portion, thereby heating and annealing the defective portion.

〔Example〕

Examples of the present invention will be described below. The figure shows an example of an n-channel enhancement type MO5I transistor. 1 is a p-type silicon semiconductor substrate, 2
is an n-type epitaxial growth layer, 3 is a p-type drain region, 4 is a p-type source region, 5 is a drain electrode made of aluminum wiring, 6 is a similar source electrode, 7 is a gate electrode, and 8 is a silicon oxide film ( S i Ox ).

The crystal defects described above are likely to occur in the oxide film 8, epitaxial growth layer 2, drain region 3, and source region.

Therefore, in the present invention, the forbidden band width of silicon (1.1 eV)
Infrared light (wavelength of about 1,500 nm) has lower energy than the energy of (wavelength of about 1,200 nm)
is irradiated from the surface 1a of the semiconductor substrate 1 opposite to the oxide film 8 side (the back surface of the silicon wafer).

As a result, the infrared light passes through the substrate 1 made of silicon, the epitaxial growth layer 2, the drain region 3, and the source region 4, and is absorbed at the interface with the oxide film 8. Therefore, heat generation occurs in the absorbing portion, and the silicon crystal defect portion at the interface is efficiently heated, annealed, and the defect is removed. At this time, there is no influence from the aluminum wiring (electrodes 5, 6) or the oxide film 8.

〔Effect of the invention〕

As described above, according to the present invention, since light is irradiated from the back side of the wafer, the interface with the oxide film can be efficiently annealed even after the aluminum wiring is completed.
It becomes possible to remove crystal defects occurring in that part.

[Brief explanation of the drawing]

The figure is MO3 for explaining the present invention! - a sectional view of a transistor; DESCRIPTION OF SYMBOLS 1... Silicon semiconductor substrate, 2... Epitaxial growth layer, 3... Drain region, 4... Source region, 5... Drain electrode, 6... Source electrode, 7...
- Gate electrode, 8... silicon oxide film. Patent applicant New Japan Radio Co., Ltd. Agent Patent attorney Tsuneaki Nagao SG D, 1, evening

Claims (1)

[Claims] (1) In an annealing method for removing crystal defects on one side of a semiconductor, irradiating light with energy smaller than the forbidden band width of the semiconductor from the side opposite to the above-mentioned side of the semiconductor, A method for annealing a semiconductor device, characterized in that the defective portion is absorbed by the defective portion and the defective portion is heated and annealed.