CN-121973342-A - Wafer cutting depth control method and system and wafer dicing machine

CN121973342ACN 121973342 ACN121973342 ACN 121973342ACN-121973342-A

Abstract

The application provides a wafer cutting depth control method and system and a wafer dicing machine, which are used for solving the problem of insufficient cutting depth precision caused by uneven thickness of a wafer and uneven cutting table top. The method comprises the steps of firstly, establishing a fixed compensation relation value between a height measurement value and a laser ranging value of a cutting cutter body through calibration, secondly, scanning a plurality of points on the surface of a wafer by using a laser ranging instrument before cutting, fitting a curved surface model of the surface appearance of the wafer through an interpolation algorithm, and finally, obtaining the height measurement from the curved surface model according to the current cutting point coordinate in the cutting process, and combining the fixed compensation relation value with a preset cutting depth to calculate and adjust the position of the cutter body in real time. The system comprises corresponding hardware and a control module. The application realizes constant control of the cutting depth through dynamic compensation, and greatly improves the precision and consistency of the cutting process.

Inventors

MENG QINGSONG
WANG JUNJIE
YUAN XIAOCHUN
LIU TAO
YANG XIAOXIONG

Assignees

北京中电科电子装备有限公司

Dates

Publication Date: 20260505
Application Date: 20260202

Claims (9)

1. The wafer cutting depth control method is characterized by comprising the following steps of: s1, calibrating, namely selecting a plurality of calibration points on a cutting table top, respectively acquiring height measurement values of a cutting knife body at the plurality of calibration points, and acquiring first laser distance values of a laser range finder on the cutting table top at the plurality of calibration points; s2, a curved surface modeling step, namely measuring second laser distance values of a plurality of measuring points on the surface of the wafer by using the laser range finder before cutting, and fitting by adopting an interpolation algorithm based on coordinates of the measuring points and corresponding second laser measured values to generate a curved surface model of the surface of the wafer; And S3, dynamically compensating the cutting step, namely calculating a predicted laser distance value of a current cutting point based on the curved surface model according to the coordinates of the point in the cutting process, calculating a target height position of the cutting knife body in real time according to the compensation relation value, the predicted laser distance value and a preset cutting depth parameter, and controlling the cutting knife body to move to the target height for cutting.
2. The method of claim 1, wherein the step S1 specifically comprises: selecting at least four calibration points on a cutting table; For each of the calibration points, the following operations are performed: controlling the cutter body to sequentially contact the calibration points, and recording the coordinates of the calibration points and the corresponding cutter body height measurement values; controlling a laser range finder to measure a first laser distance value at the standard point and recording; and determining that the sum of the cutter body measured height values and the first laser distance values of all the standard points is kept constant based on the recorded cutter body measured height values and the first laser distance values, wherein the constant value is the compensation relation value.
3. The wafer dicing depth control method according to claim 2, wherein before the performing ranging for each of the calibration points, step S1 further comprises: Coordinate axis conversion is carried out based on the recorded coordinates of the calibration points, conversion angles corresponding to the calibration points are obtained through calculation, and the conversion angles are based on the following calculation formula: ; Wherein, the In order to switch the angle of the beam, Is the horizontal axis coordinate of the calibration point, Is the vertical axis coordinate of the calibration point.
4. The method according to claim 1, wherein in the step S2, the number of the plurality of measurement points is 9, and the interpolation algorithm is a barycentric lagrangian interpolation algorithm.
5. The method of claim 4, further comprising, after step S2 and before step S3: The safety planning step comprises the steps of calculating a maximum laser distance value and a minimum laser distance value of the surface of the wafer based on the curved surface model, judging whether cutting requirements are met according to the maximum laser distance value and cutting depth parameters, and calculating cutting pick-up cutter positions according to the minimum laser distance value and preset pick-up cutter reserved quantity parameters.
6. The method for controlling wafer dicing depth according to claim 1, wherein in step S3, the predicted laser distance value of the current dicing point is calculated based on the curved surface model, specifically comprising converting the coordinates of the current dicing point into coordinates based on the center of the wafer, and calculating by using a gravity center lagrangian difference formula based on the coordinates of the plurality of test points and the second laser distance value.
7. The method of claim 1, wherein in step S3, the target height position of the cutter body is calculated in real time based on the following calculation formula: ; Wherein, the Is the target height position of the cutter body, In order to compensate for the value of the relationship, In order to predict the laser distance value, Is a preset cutting depth parameter.
8. A wafer dicing depth control system for implementing the wafer dicing depth control method according to any one of claims 1 to 7, comprising: a Z-axis system for cutting the cutter body and driving the cutter body to move; The laser range finder is fixedly arranged relative to the cutter body; A control module configured to perform: Calibrating to obtain a compensation relation value; a curved surface modeling operation to produce a wafer surface curved surface model; And the dynamic compensation control operation is performed to calculate and control the Z-axis system to position the cutting cutter body to a target height position in real time according to the curved surface model, the compensation relation value and the preset cutting depth during cutting.
9. A wafer dicing saw comprising the wafer dicing depth control system of claim 8.

Description

Wafer cutting depth control method and system and wafer dicing machine Technical Field The application belongs to the field of semiconductor production equipment, and particularly relates to a wafer cutting depth control method and system and a wafer dicing saw. Background In semiconductor wafer dicing (dicing) processes, precise control of the dicing depth is critical, which directly affects device performance and subsequent process yields. The conventional cutting depth control method is generally based on two assumptions, namely that the cutting table surface is an ideal horizontal plane and that the thickness of the wafer is uniform. Based on the above, the conventional practice is that before the process, the height from the cutter body to a certain point of the table top is manually measured as a reference, the thickness of a plurality of points of the wafer is measured, the arithmetic average value of the thicknesses is taken as the whole thickness, and then the target height position of the cutter body is calculated by combining the preset cutting depth. The cutter body will maintain this fixed height for operation throughout the cutting process. However, the actual production environment deviates significantly from the ideal assumption described above. First, machining and mounting errors result in cutting tables that are not perfectly horizontal, with microscopic undulations. Second, the wafer itself has regional non-uniform variations in thickness due to manufacturing process limitations. The conventional method performs a homogenization treatment on the uneven thickness and the uneven table top, and ignores the truly existing spatial variations. This results in a fluctuation in the dicing depth at different locations of the wafer, where the wafer is thicker or the mesa is lower, and where the wafer is thinner or the mesa is higher, the substrate may be over-diced or even damaged. With the continuous downsizing and increasingly complex structure of semiconductor devices, higher requirements are put on the precision and consistency of the cutting depth, and the conventional static compensation method based on the average value is difficult to meet the requirements of the current high-precision process. Therefore, a high-precision cutting depth control technology capable of sensing and compensating the comprehensive influence of the surface morphology of the wafer and the flatness of the table top in real time is needed. Disclosure of Invention The application provides a wafer cutting depth control method, which comprises the following specific contents: the wafer cutting depth control method is characterized by comprising the following steps of: s1, calibrating, namely selecting a plurality of calibration points on a cutting table top, respectively acquiring height measurement values of a cutting knife body at the plurality of calibration points, and acquiring first laser distance values of the laser range finder on the cutting table top at the plurality of calibration points; S2, a curved surface modeling step, namely measuring second laser distance values of a plurality of measuring points on the surface of the wafer by using a laser range finder before cutting, and fitting by adopting an interpolation algorithm based on coordinates of the measuring points and corresponding second laser measured values to generate a curved surface model of the surface of the wafer; And S3, dynamically compensating the cutting step, namely calculating a predicted laser distance value of a current cutting point based on a curved surface model according to the coordinates of the point in the cutting process, calculating a target height position of the cutting knife body in real time according to the compensation relation value, the predicted laser distance value and a preset cutting depth parameter, and controlling the cutting knife body to move to the target height for cutting. The application couples and compensates the geometrical error of the equipment (by calibrating the compensation relation value), the real three-dimensional morphology of the wafer (by interpolating the simulated surface curved surface model of the wafer) and the real-time motion control (by dynamically calculating the target height for cutting) in the same algorithm flow. The reference error caused by uneven cutting table top is eliminated, and the micro fluctuation of the wafer surface is more actively adapted. Therefore, the high-precision cutting of the wafer is realized, and a reliable basis is provided for the subsequent process. In some embodiments, step S1 specifically includes: selecting at least four calibration points on a cutting table; For each of the calibration points, the following operations are performed: controlling the cutter body to sequentially contact the calibration points, and recording the coordinates of the calibration points and the corresponding cutter body height measurement values; controlling a laser range fin