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CN-121985745-A - Ion implantation angle calibration method and system

CN121985745ACN 121985745 ACN121985745 ACN 121985745ACN-121985745-A

Abstract

The invention discloses an ion implantation angle calibration method and system, comprising the following steps of S1, calibrating a reference machine by a five-point method to obtain a standard quadratic function curve, obtaining a standard coefficient a 0 , S2, selecting three test angles from the machine to be calibrated to perform ion implantation on a wafer, measuring corresponding thermal wave values, and fitting to obtain an initial quadratic function curve, S3, adding two virtual angles on the basis of the initial quadratic function, adjusting thermal wave value fitting corresponding to the virtual angles to obtain a calibration quadratic function curve, obtaining a calibration coefficient a 1 , and calculating a correction value to the machine to be calibrated based on the calibration quadratic function to calibrate, wherein the deviation between the calibration coefficient a 1 and the standard coefficient a 0 is less than 5, and S4, the correction value is-b 1 /2a 1 . The method reduces 5 test wafers required by the traditional five-point method to 3, reduces test cost and time, and ensures the reliability of calibration by introducing virtual angle points and matching standard quadratic term coefficients a 0 .

Inventors

  • LIU TINGTING

Assignees

  • 重庆芯联微电子有限公司

Dates

Publication Date
20260505
Application Date
20251226

Claims (10)

  1. 1. An ion implantation angle calibration method is characterized by comprising the following steps: S1, calibrating a reference machine by a five-point method, and obtaining a standard quadratic function curve y=a 0 x 2 +b 0 x+c 0 by taking an injection angle as an independent variable and a corresponding thermal wave value as a dependent variable to obtain a standard coefficient a 0 ; S2, selecting three test angles from a machine to be calibrated to perform ion implantation on a wafer, measuring a corresponding thermal wave value, wherein the test angles are independent variables, and the corresponding thermal wave values are dependent variables, and fitting to obtain an initial quadratic function curve; S3, adding two virtual angles on the basis of the initial quadratic function, and adjusting the thermal wave value fitting corresponding to the virtual angles to obtain a calibration quadratic function curve y=a 1 x 2 +b 1 x+c 1 , so as to obtain a calibration coefficient a 1 , wherein the deviation between the calibration coefficient a 1 and the standard coefficient a 0 is less than 5%; And S4, calculating a correction value to the machine to be calibrated based on the calibration quadratic function, wherein the correction value is-b 1 /2a 1 .
  2. 2. The ion implantation angle calibration method according to claim 1, wherein in step S1, the five-point method calibration step comprises: respectively carrying out ion implantation on five test wafers at five different implantation angles on the reference machine; measuring a thermal wave value corresponding to each test wafer ion implantation; And fitting the standard quadratic function curve by taking the injection angle as an independent variable and the corresponding thermal wave value as a dependent variable to obtain the standard coefficient a 0 .
  3. 3. The method of claim 2, wherein the implant angle of the five-point method comprises 0 ° and two pairs of positive and negative angle values symmetrical about 0 °.
  4. 4. The method according to claim 1, wherein in step S2, the test angle includes a center angle and two offset angles symmetrically disposed about the center angle.
  5. 5. The method of claim 4, wherein the center angle is 0 ° and the offset angle is selected from the range of-6 ° to 6 °.
  6. 6. The method of claim 4, wherein the two virtual angles are symmetrically disposed about the center angle.
  7. 7. The method of claim 4, wherein two of the virtual angles are outside an angle interval defined by the offset angle.
  8. 8. The method of claim 7, wherein the offset of the virtual angle relative to the offset angle is equal to the offset of the offset angle relative to the center angle.
  9. 9. The method of claim 1, wherein the thermal wave value is measured by a thermal wave probe.
  10. 10. An ion implantation angle calibration system, comprising: the ion implantation module is used for performing ion implantation at different angles on the wafer; the thermal wave measuring module is used for acquiring a thermal wave value of the wafer after ion implantation; The data processing module is in communication connection with the thermal wave measuring module and is used for calculating and outputting an angle correction value; and the machine control module is in communication connection with the data processing module and is used for calibrating the machine to be calibrated according to the correction value.

Description

Ion implantation angle calibration method and system Technical Field The invention belongs to the field of semiconductors, and particularly relates to an ion implantation angle calibration method and system. Background With the development of semiconductor technology to large-scale and ultra-large-scale integrated circuits, the size of semiconductor devices is continuously reduced, higher requirements are put on the control precision of ion implantation technology, and the control of implantation angles has important influence on the quality of devices. At present, the injection angle is monitored mainly by adopting a five-point method and a single-point method. Five-point method generally selects five discrete angles around a nominal angle (tin/twist=0°) for ion implantation, draws a relationship curve of process response and angle by measuring a thermal wave value or a sheet resistance of a wafer corresponding to each angle, and calculates an actual angle deviation (-b/2 a) by fitting a quadratic function. Although the method has higher precision, at least five test wafers are consumed for each calibration, and considerable test cost and time loss are caused in a mass production environment. The single point method saves cost, but cannot accurately reflect the angular offset. Therefore, there is a need to develop an ion implantation angle calibration method and system, which can reduce the number of test samples and the cost while ensuring the calibration accuracy. Disclosure of Invention The invention aims to solve all or part of the problems, and provides an ion implantation angle calibration method and system, wherein 5 test wafers required by the traditional five-point method are reduced to 3 on the premise of ensuring the calibration precision, and the test cost and time are reduced; by introducing virtual angle points and matching the standard quadratic term coefficient a 0, the reliability of three-point method calibration is ensured, efficiency and accuracy are both considered, and the angle calibration of the ion implanter with high efficiency, low cost and high precision is realized. The invention provides an ion implantation angle calibration method which comprises the following steps of S1, calibrating a reference machine by a five-point method, fitting to obtain a standard quadratic function curve y=a 0x2+b0x+c0, obtaining a standard coefficient a 0, S2, selecting three test angles from a machine to be calibrated, carrying out ion implantation on a wafer, measuring corresponding heat wave values, fitting to obtain an initial quadratic function curve, S3, adding two virtual angles on the basis of the initial quadratic function, adjusting the heat wave value fitting corresponding to the virtual angles to obtain a calibration quadratic function curve y=a 1x2+b1x+c1, obtaining a calibration coefficient a 1, and S4, calculating a symmetry axis x= -b 1/2a1 based on the calibration quadratic function, and feeding the symmetry axis x= -b 1/2a1 back to the machine to be calibrated as a correction value for calibration. The method reduces 5 test wafers required by the traditional five-point method to 3, reduces test cost and time, and ensures the reliability of calibration by introducing virtual angle points and matching standard quadratic term coefficients a 0. In the step S1, the five-point method calibration step comprises the steps of respectively carrying out ion implantation on five test wafers at five different implantation angles on the reference machine, measuring thermal wave values corresponding to the ion implantation of each test wafer, and fitting by taking the implantation angle as an independent variable and the corresponding thermal wave value as a dependent variable to obtain the standard quadratic function curve to obtain the standard coefficient a 0. And a reliable comparison basis is provided for the subsequent three-point calibration, so that the calibration precision is ensured while the test cost is reduced. The implantation angle of the five-point method includes 0 ° and two pairs of positive and negative angle values symmetrical about 0 °. The symmetrical angle distribution and the thermal wave value response accurately represent the physical relationship between the ion implantation angle and the lattice damage, and ensure that the standard coefficient a 0 has good process representativeness and repeatability. In step S2, the test angle includes a center angle and two symmetrical offset angles. Reasonable basis is provided for the addition of the subsequent virtual points, and the rationality of the data is ensured by the selection of the test angles. The center angle is 0 degrees, and the offset angle is selected from-6 degrees to 6 degrees. The center angle is set to be 0 degrees, the conventional operation of the ion implantation process is met, the offset angle is limited to be within +/-6 degrees, the angle offset range of the machine is covered, meanwhile, inaccurate da