Carbon materials for carbon implantation

Abstract

A method of implanting carbon ions into a target substrate, including: ionizing a carbon containing dopant material to produce a plasma having ions; optionally co-flowing an additional gas or series of gases with the carbon-containing dopant material; and implanting the ions into the target substrate. The carbon-containing dopant material is of the formula CwFxOyHz wherein if w=1, then x>0 and y and z can take any value, and wherein if w>1 then x or y is >0, and z can take any value. Such method significantly improves the efficiency of an ion implanter tool, in relation to the use of carbon source gases such as carbon monoxide or carbon dioxide.

Description

TECHNICAL FIELDThe present disclosure relates to ion implantation methods and systems, and more particularly, to carbon materials for carbon ion implantation in such systems.BACKGROUNDIon implantation is used in integrated circuit fabrication to accurately introduce controlled amounts of dopant impurities into semiconductor wafers and is one of the processes of microelectronic / semiconductor manufacturing. In such implantation systems, an ion source ionizes a desired dopant element gas, and the ions are extracted from the source in the form of an ion beam of desired energy. Extraction is achieved by applying a high voltage across suitably-shaped extraction electrodes, which incorporate apertures for passage of the extracted beam. The ion beam is then directed at the surface of a workpiece, such as a semiconductor wafer, in order to implant the workpiece with the dopant element. The ions of the beam penetrate the surface of the workpiece to form a region of desired conductivity.Severa...

AI Technical Summary

Benefits of technology

In another aspect, the present disclosure relates to a method of improving the efficiency of an ion implanter tool. This method comprises: selecting a carbon-containing dopant material of the formula CwFxOyHz for use in the ion implanter tool in a chamber, wherein w, x, y and z are as defined above; ionizing the carbon-containing dopant material; and implanting a carbon ion from the ionized carbon-containing dopant material using the ion implanter tool. The selecting of the material of the formula CwFxOyHz minimizes the amount of carbon and / or non-carbon elements deposited in the chamber after the implanting of the carbon ion. In doing so, the performance of the ion source is optimized.

Problems solved by technology

The use of carbon monoxide or carbon dioxide gases can result in oxidation of the metal surfaces within the plasma source (arc chamber) of the ion implanter tool, and can also result in carbon residues depositing on electrical insulators.

These phenomena reduce the performance of the implanter tool, thereby resulting in the need to perform frequent maintenance.

Oxidation can result in inefficiencies in the implantation process.

In reality, feedstock gas ionization and fragmentation can results in such undesirable effects as arc chamber components etching or sputtering, deposition on arc chamber surfaces, redistribution of arc chamber wall material, etc.

In particular, the use of carbon monoxide or carbon dioxide gases can result in carbon deposition within the chamber.

This can be a contributor to ion beam instability, and may eventually cause premature failure of the ion source.

The residue also forms on the high voltage components of the ion implanter tool, such as the source insulator or the surfaces of the extraction electrodes, causing energetic high voltage sparking.

Such sparks are another contributor to beam instability, and the energy released by these sparks can damage sensitive electronic components, leading to increased equipment failures and poor mean time between failures (MTBF).

In another instance of undesirable deposition, various materials (such as tungsten) can accumulate on components during extended ion implantation processes.

Once enough tungsten is accumulated, the power used to maintain temperature sufficient to meet the beam current setpoint may not be sustainable.

This causes loss of ion beam current, which leads to conditions that warrant the replacement of the ion source.

The resultant performance degradation and short lifespan of the ion source reduces productivity of the ion implanter tool.

Yet another cause of ion source failure is the erosion (or sputtering) of material.

Because sputtering is dominated by the heaviest ions in the plasma, the sputtering effect may worsen as ion mass increases.