Coated platen design for plasma immersion ion implantation

Details Coated platen design for plasma immersion ion implantation Coated platen design for plasma immersion ion implantation

1998-12-18

2001-04-17

McDonald, Rodney (Department: 1753)

Chemistry: electrical and wave energy

Processes and products

Coating, forming or etching by sputtering

C204S192320, C204S298320, C204S298360, C204S298150, C118S7230IR, C118S7230IR, C118S7230MP, C118S728000, C118S733000, C427S523000, C427S524000, C427S527000, C156S345420

Reexamination Certificate

active

06217724

ABSTRACT:

BACKGROUND OF THE INVENTION
The present invention relates to the manufacture of integrated circuits. More particularly, the present invention provides a technique for selectively controlling a distribution of impurities that are implanted using a plasma immersion ion implantation or plasma ion source system for the manufacture of semiconductor integrated circuits, for example. But it will be recognized that the invention has a wider range of applicability; it can also be applied to other substrates for multi-layered integrated circuit devices, three-dimensional packaging of integrated semiconductor devices, photonic devices, piezoelectronic devices, microelectromechanical systems (“MEMS”), sensors, actuators, solar cells, flat panel displays (e.g., LCD, AMLCD), biological and biomedical devices, and the like.
Integrated circuits are fabricated on chips of semiconductor material. These integrated circuits often contain thousands, or even millions, of transistors and other devices. In particular, it is desirable to put as many transistors as possible within a given area of semiconductor because more transistors typically provide greater functionality, and a smaller chip means more chips per wafer and lower costs. Some integrated circuits are fabricated on a slice or wafer, of single-crystal (monocrystalline) silicon, commonly termed a “bulk” silicon wafer. Devices on such “bulk” silicon wafer typically use processing techniques such as ion implantation or the like to introduce impurities or ions into the substrate. These impurities or ions are introduced into the substrate to selectively change the electrical characteristics of the substrate, and therefore devices being formed on the substrate. Ion implantation provides accurate placement of impurities or ions into the substrate. Ion implantation, however, is expensive and generally cannot be used effectively for introducing impurities into a larger substrate such as glass or a semiconductor substrate, which is used for the manufacture of flat panel displays or the like.
Accordingly, plasma treatment of large area substrates such as glass or semiconductor substrates has been proposed or used in the fabrication of flat panel displays or 300 mm silicon wafers. Plasma treatment is commonly called plasma immersion ion implantation (“PIII”) or plasma source ion implantation (“PSI”). Plasma treatment generally uses a chamber, which has an inductively coupled plasma source, for generating and maintaining a plasma therein. A large voltage differential between the plasma and the substrate to be implanted accelerates impurities or ions from the plasma into the surface or depth of the substrate. A variety of limitations exist with the convention plasma processing techniques.
A major limitation with conventional plasma processing techniques is the maintenance of the uniformity of the plasma density and chemistry over such a large area is often difficult. As merely an example, inductively or transformer coupled plasma sources (“ICP” and “TCP,” respectively) are affected both by difficulties of maintaining plasma uniformity using inductive coil antenna designs. Additionally, these sources are often costly and generally difficult to maintain, in part, because such sources which require large and thick quartz windows for coupling the antenna radiation into the processing chamber. The thick quartz windows often cause an increase in rf power (or reduction in efficiency) due to heat dissipation within the window.
Other techniques such as Electron Cyclotron Resonance (“ECR”) and Helicon type sources are limited by the difficulty in scaling the resonant magnetic field to large areas when a single antenna or waveguide is used. Furthermore, most ECR sources utilize microwave power which is more expensive and difficult to tune electrically. Hot cathode plasma sources have been used or proposed. The hot cathode plasma sources often produce contamination of the plasma environment due to the evaporation of cathode material. Alternatively, cold cathode sources have also be used or proposed. These cold cathode sources often produce contamination due to exposure of the cold cathode to the plasma generated.
A pioneering technique has been developed to improve or, perhaps, even replace these conventional sources for implantation of impurities. This technique has been developed by Chung Chan of Waban Technology in Massachusetts, now Silicon Genesis Corporation, and has been described in U.S. Pat. No. 5,653,811 (“Chan”), which is hereby incorporated by reference herein for all purposes. Chan generally describes techniques for treating a substrate with a plasma with an improved plasma processing system. The improved plasma processing system, includes, among other elements, at least two rf sources, which are operative to generate a plasma in a vacuum chamber. By way of the multiple sources, the improved plasma system provides a more uniform plasma distribution during implantation, for example. It is still desirable, however, to provide even a more uniform plasma for the manufacture of substrates. Additionally, Chan's techniques can create particulate contamination during implantation processes using his plasma processing system.
From the above, it is seen that an improved technique for introducing impurities into a substrate is highly desired.
SUMMARY OF THE INVENTION
According to the present invention, a technique including a method and system for introducing impurities into a substrate using plasma immersion ion implantation is provided. In an exemplary embodiment, the present invention provides system with a novel susceptor with a coating that reduces particulate contamination that may attach to a substrate surface during an implantation process.
In a specific embodiment, the present invention provides a plasma treatment system for implantation with a novel susceptor with a coating thereon. The system has a variety of elements such as a chamber in which a plasma is generated in the chamber. The system also has a susceptor disposed in the chamber to support a substrate such as a silicon substrate. A silicon bearing compound is coated on the susceptor for reducing impurities or non-silicon materials that may sputter off of the susceptor. In a specific embodiment, the chamber has a plurality of substantially planar rf transparent windows on a surface of the chamber. The system also has an rf generator and at least two rf sources in other embodiments. A silicon bearing compound is coated onto the interior surfaces of the chamber. This coating reduces impurities or non-silicon materials that may sputter off of the interior surfaces of the chamber during plasma immersion ion implantation.
In an alternative embodiment, the present invention provides a method for forming a substrate using a plasma immersion ion implantation system. The method includes a step of providing a silicon substrate, which has a surface, onto a susceptor within a plasma immersion ion implantation chamber. The method then introduces and/or accelerates particles in a uniform, directional manner toward and into the surface to uniformly place the ions into a selected depth across a plane of the substrate. During the introducing step, the method sputters silicon bearing compounds off of interior chamber surfaces and portions of the susceptor. These silicon bearing compounds do not detrimentally influence the implantation process and reduce a possibility of introducing any impurities or non-silicon bearing compounds that can attach to the silicon substrate surface.
Numerous advantages are achieved by way of the present invention over conventional techniques. For example, the present invention provides a relatively easy to implement device for improving implantation uniformity across a substrate such as a wafer in a specific embodiment. In some embodiments, the present invention provides a system that produces fewer non-silicon particles (e.g., aluminum, iron, chrome, nickel) that may introduce defects into a substrate, for example. In still other embodiments, the present invention can be implem

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