CN104637850A

CN104637850A - Dynamic wafer centering method

Info

Publication number: CN104637850A
Application number: CN201310554530.6A
Authority: CN
Inventors: 王冲
Original assignee: Shenyang Xinyuan Microelectronics Equipment Co Ltd
Current assignee: Shenyang Xinyuan Microelectronics Equipment Co Ltd
Priority date: 2013-11-08
Filing date: 2013-11-08
Publication date: 2015-05-20

Abstract

The invention relates to the LED and IC industry, in particular to a method measuring the wafer center dynamically and assisting a robot in centering during wafer transportation. The method includes adopting two laser sensors to acquire wafer edge signals, reading a robot motor encoder signal, acquiring the wafer moving distance data, determining the wafer center through data computation by a computer, transmitting the data to the robot in real time, allowing the robot to act the corresponded actions to align the wafer center with a theoretical center, and implementing the dynamic centering. The method can be implemented in the wafer moving process, structure is simple, the accuracy is higher as compared with that of mechanical centering, the cost is much lower as compared with that of CCD imaging, the centering station can be reduced, and the robot utilization rate is increased.

Description

Wafer dynamic centering method

Technical Field

The invention relates to the LED and IC industry, in particular to a method for dynamically measuring the center of a wafer and assisting a robot in center alignment in the wafer carrying process.

Background

In the LED and IC industries, it is often necessary to use robots to transport wafers in different processing units, and the conventional methods include two methods, one is a mechanical clamping method, which has low precision and one more station for the robot to operate, thus reducing the use efficiency of the robot, and the other is CCD imaging, which analyzes the pattern by a computer to confirm the center of the wafer, which has high precision but high cost.

Disclosure of Invention

Aiming at the defects in the prior art, the invention aims to provide a wafer dynamic centering method.

The technical scheme adopted by the invention for realizing the purpose is as follows: a wafer dynamic centering method comprises the following steps:

rotating the flat edge of the wafer to the right front of the movement of the manipulator, and arranging a first sensing point and a second sensing point which are formed by two sensors on the path of the movement of the wafer;

when the wafer passes through the first sensing point and the second sensing point, the first sensing point and the second sensing point send out electric signals; when the wafer leaves the first sensing point and the second sensing point, the electric signals sent by the first sensing point and the second sensing point disappear;

and calculating the deviation between the coordinate of the center of the end point and the coordinate of the set center of the circle, returning the deviation to the robot, and revising the set center of the circle stored by the robot.

The coordinate f (x) of the center of the end point₁,y₁) The calculation method comprises the following steps:

the wafer at the end point first passes the edge point C (x) of the first sensor_C,y_C) The position coordinate A (x) of the first sensor_A,y_A) First passing through the edge point D (x) of the second sensor_D,y_D) Of the second sensorPosition coordinate B (x)_B,y_B) Calculating the coordinate f (x) of the center of the end point by the coordinates of any three points₁,y₁)：

x_{1} = \frac{(u - v)}{(k_{1} - k_{2})}

Wherein,

calculating the deviation delta (x) between the set circle center and the end point circle center_Δ,y_Δ)=f(x₁,y₁)-P(x₀,y₀)；

I.e. x_Δ=x₁-x₀，y_Δ=y₁-y₀Wherein, P (x)₀,y₀) Is the coordinate of the set circle center.

The deviation between the coordinate of the end point circle center 8 and the coordinate of the set circle center needs to be checked:

checking whether the selected 3 points meet the requirements by calculating the diameter of the wafer, and selecting the center coordinate f (x) of the end point₁,y₁) And one remaining point when calculating the coordinates of the circle center:

comparing the calculated result with the set wafer size, setting a percentage, and when the calculated size is divided by the set size within the set range, the center coordinate is valid, and if not, re-measuring.

The invention has the following advantages and beneficial effects:

1. the coordinate data of the wafer center can be transmitted to the robot controller in real time, the actual center position of the wafer is changed, and the centering is completed in the wafer movement process.

2. The method has higher precision than mechanical centering and greatly lower cost than CCD imaging.

3. The method can reduce centering stations and improve the service efficiency of the robot.

Drawings

FIG. 1 is a schematic diagram of the method of the present invention.

Wherein, 1, flattening the wafer; 2. starting a circle center; 3. starting a wafer; 4. a first sensing point; 5. an endpoint wafer; 6. setting a wafer; 7. the first length of the cord; 8. the center of the end point circle; 9. setting a circle center; 10. the second is long; 11. a second sensing point.

Detailed Description

The present invention will be described in further detail with reference to the accompanying drawings and examples.

As shown in fig. 1, the method of the present invention is intended to achieve the following objectives: the center of the wafer is coincided with the set circle center 9 after the correction.

The specification is as follows: setting the center 9 coordinate as P (x)₀,y₀) The coordinate of the first sensing point 4 is A (x)_A,y_A) The second sensing point 11 has the coordinate B (x)_B,y_B) The center of the circle of the end point is 8 coordinates of f (x)₁,y₁) The initial 2 coordinates of the center of the circle are g (x)₂,y₂) The first length is 7 and the length is S₁The second length is 10 and the length is S₂。

Before work, the wafer flat edge 1 is rotated to the position right in front of the motion of the manipulator, interference of the flat edge is avoided, the first sensing point 4 and the second sensing point 11 are installed on a path where the robot takes out a wafer, when the robot carries the wafer to pass through the sensing points, the first sensing point 4 or the second sensing point 11 sends out signals, when the wafer moves out of the first sensing point 4 or the second sensing point 11, the signals disappear, the upper computer reads data of a robot encoder to obtain the lengths of the first and second lengths 7 and 10, and in order to reduce calculated amount, the robot moves along the y axis of the coordinate axes.

The coordinate of the contact point between the left edge and the sensing point in the end wafer 5 state is defined as C (x)_C,y_C)，D(x_D,y_D) The 2 point coordinates can be calculated according to the following formula:

C(x_C,y_C)=A(x_A,y_A)-S₁=C(x_A-s₁,y_A)

D(x_D,y_D)=B(x_B,y_B)-S₂=D(x_B-s₂,y_B)

in the end point wafer 5 state, four points A, B, C and D are all on the edge of the wafer, and the coordinates of the four points are respectively A (x)_A,y_A)、B(x_B,y_B)、C(x_A-s₁,y_A)、D(x_B-s₂,y_B) Setting upThe coordinate of the circle center is P (x)₀,y₀) Calculating the center coordinates of the end point wafer 5 according to the four coordinates A, B, C and D, and setting the center coordinates of the end point wafer 5 and the center coordinates to be P (x)₀,y₀) And comparing to obtain a deviation value between the actual center and the set center of the wafer, returning the deviation value to the robot by the computer, and revising the coordinate value before the robot puts the wafer into the next station so as to achieve the aim that the center of the wafer is consistent with the set center when the wafer is put into the station.

The specific calculation process is as follows:

1. calculating the coordinate f (x) of the center (8) of the end point circle₁,y₁)：

Taking coordinates of any three points A, B, C and D, taking three points A, B and C as an example

k_{2} = \frac{(x_{A} - x_{C})}{(x_{A} - x_{C})}

x_{1} = \frac{(u - v)}{(k_{1} - k_{2})}

2. Calculating the deviation delta (x) between the set circle center (9) and the actual wafer center (i.e. the end point circle center (8))_Δ,y_Δ)：

Δ(x_Δ,y_Δ)=f(x₁,y₁)-P(x₀,y₀)

x_Δ=x₁-x₀

y_Δ=y₁-y₀

Adding the center deviation delta (x) to the original coordinates_Δ,y_Δ) And obtaining the coordinates of the robot to be put into the station.

3. Data checking

Checking whether the selected 3 points meet the requirements by calculating the diameter of the wafer, and selecting the coordinate f (x) of the center (8) of the end point circle₁,y₁) And one point left when calculating the coordinates of the circle center, taking point D as an example:

The method has simple structure, low cost and quick response, and can be widely applied to IC and LED industries.

Claims

1. A wafer dynamic centering method is characterized by comprising the following steps:

rotating the flat edge (1) of the wafer to the position right ahead of the movement of the manipulator, and arranging a first sensing point (4) and a second sensing point (11) which are formed by two sensors on the movement path of the wafer (3);

when the wafer (3) passes through the first sensing point (4) and the second sensing point (11), the first sensing point (4) and the second sensing point (11) send out electric signals; when the wafer (3) leaves the first sensing point (4) and the second sensing point (11), electric signals sent by the first sensing point (4) and the second sensing point (11) disappear;

and calculating the deviation between the coordinate of the end point circle center (8) and the coordinate of the set circle center (9), returning the deviation to the robot, and revising the set circle center (9) stored by the robot.

2. A method as claimed in claim 1, wherein the coordinate f (x) of the end point center (8) is₁,y₁) The calculation method comprises the following steps:

the wafer (5) at the end point is first taken to pass the edge point C (x) of the first sensor (4)_C,y_C) The position coordinate A (x) of the first sensor (4)_A,y_A) The edge point D (x) passing through the second sensor (11) first_D,y_D) A position coordinate B (x) of the second sensor (11)_B,y_B) The coordinate f (x) of the center (8) of the end point is calculated by the coordinates of any three points₁,y₁)：

x_{1} = \frac{(u - v)}{(k_{1} - k_{2})}

Wherein,

calculating the deviation delta (x) between the set circle center (9) and the end point circle center (8)_Δ,y_Δ)=f(x₁,y₁)-P(x₀,y₀)

I.e. x_Δ=x₁-x₀，y_Δ=y₁-y₀Wherein, P (x)₀,y₀) The coordinates of the circle center (9) are set.

3. A method as claimed in claim 2, wherein the deviation of the coordinates of the end point center (8) from the coordinates of the set center (9) requires data checking:

checking whether the selected 3 points meet the requirements by calculating the diameter of the wafer, and selecting the coordinate f (x) of the center (8) of the end point circle₁,y₁) And one remaining point when calculating the coordinates of the circle center: