# US 6,050,218 A · Dosimetry cup charge collection in plasma immersion ion implantation > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 6,050,218 A - Document ID: US6050218A - Status: Granted - Kind: A - Application number: 09/162,096 - Filed: 1998-09-28 - Granted: 2000-04-18 - Earliest claimed: 1998-09-28 - Assignees: Eaton Corporation - Inventors: Jiong Chen; Peter Kellerman; A. Stuart Denholm - Web page: https://patentgrep.com/patent/US6050218A ## CPC - H01J 37/32412: {Plasma immersion ion implantation} - C23C 14/48: Ion implantation - H01J 37/3299: {Feedback systems} - H01J 2237/31703: Dosimetry - H01J: ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS (spark-gaps H01T; electric arc lamps H05B31/00; particle accelerators H05H) - C23C: COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL (making metal-coated products by extrusion B21C23/22; covering with metal by connecting pre-existing layers to articles, see the relevant places, e.g. B21D39/00, B23K; metallising of glass C03C; metallising mortars, concrete, artificial stone, ceramics or natural stone C04B41/00; enamelling of, or applying a vitreous layer to, metals C23D; treating metal surfaces or coating of metals by electrolysis or electrophoresis C25D; single-crystal film growth C30B; by metallising textiles D06M11/83; decorating textiles by locally metallising D06Q1/04) ## Abstract Method and apparatus for causing ions to impact a workpiece implantation surface. A process chamber defines a chamber interior into which one or more workpieces can be inserted for ion treatment. An energy source sets up an ion plasma within the process chamber. A support positions one or more workpieces within an interior region of the process chamber so that an implantation surface of the one or more workpieces is positioned within the ion plasma. A pulse generator in electrical communication with the workpiece support applies electrical pulses for attracting ions to the support. One or more dosimetry cups including an electrically biased ion collecting surface are disposed around the workpiece support to measure implantation current. An implantation controller monitors signals from the one or more dosimetry cups to control ion implantation of the workpiece. ## Claims ### Claim 1 An ion implantation system for causing ions to impact an implantation surface comprising: a) a process chamber defining a chamber interior into which one or more workpieces can be inserted for ion treatment; b) an energy source for setting up an ion plasma within the process chamber; c) a support for positioning one or more workpieces within an interior region of the process chamber so that an implantation surface of the one or more workpieces is positioned within the ion plasma; d) a pulse generator in electrical communication with the workpiece support for applying electrical pulses for attracting ions to the support; e) one or more dosimetry cups including an electrically biased ion collecting surface parallel to the implantation surface; and f) an implantation controller for monitoring signals from the one or more dosimetry cups to control ion implantation of the one or more workpieces. ### Claim 2 (depends on 1) The ion implantation system of claim 1 wherein the dosimetry cup further includes: a) a negatively biased electrode to repel secondary electrons from the collecting surface and electrons from the plasma; and b) a positively biased ion collecting surface to repel plasma ions. ### Claim 3 (depends on 1) The ion implantation system of claim 1 wherein the one or more dosimetry cup have generally circular apertures. ### Claim 4 (depends on 1) The ion implantation system of claim 1 further including multiple dosimetry cups with apertures forming a sector ring shape. ### Claim 5 (depends on 2) The ion implantation system of claim 2 wherein the negatively biased electrode includes an aperture with a diameter based on a plasma parameter. ### Claim 6 (depends on 5) The ion implantation system of claim 5 wherein the plasma parameter is plasma sheath thickness at the negatively biased electrode surface. ### Claim 7 (depends on 5) The ion implantation system of claim 5 wherein the aperture of the negatively biased electrode is less than twice the plasma sheath thickness. ### Claim 8 (depends on 2) The ion implantation system of claim 2 wherein the negatively biased electrode is biased to approximately -200 V relative to the workpiece support. ### Claim 9 (depends on 2) The ion implantation system of claim 2 wherein the positively biased ion collecting surface is biased to approximately +20 V relative to the workpiece support. ### Claim 10 (depends on 1) The ion implantation system of claim 1 further comprising a metal screen having holes to allow ions to enter the dosimetry cups. ### Claim 11 (depends on 10) The ion implantation system of claim 10 wherein the screen hole size is 0.04 centimeters and the screen transparency is about one half. ### Claim 12 (depends on 10) The ion implantation system of claim 10 wherein the negatively biased electrode is biased to approximately -50 V relative to the workpiece support. ### Claim 13 (depends on 10) The ion implantation system of claim 10 wherein the positively biased ion collecting surface is biased to approximately +10 V relative to the workpiece support. ### Claim 14 (depends on 1) The ion implantation system of claim 1 wherein signals from the dosimetry cup that are used by the controller are derived from electric current through the collecting surface of the dosimetry cup. ### Claim 15 (depends on 1) The ion implantation system of claim 1 wherein the parameter of the ion implantation process controlled is the duration of the implantation of the workpiece. ### Claim 16 (depends on 1) The ion implantation system of claim 1 wherein the dosimetry cups are imbedded in the workpiece support to eliminate stray capacitance to ground thereby avoiding displacement current errors. ### Claim 17 (depends on 1) The ion implantation system of claim 1 wherein signals from the dosimetry cup are extracted by means of a high band-width fiber optic transmitter to prevent stray capacitance which could cause a displacement current error.