KR20190047216A - Wafer calibrating Device and Wafer calibrating Method - Google Patents

Abstract

According to the present invention, a wafer aligning device includes: a stage on which a wafer is mounted; a rotation driving device rotating the stage; a trigger generator generating a trigger signal in accordance with angle change caused by rotation of the stage; a camera unit shooting an image of the wafer in accordance with trigger signal generation of the trigger generator; a triaxial driving device tridimensionally moving the stage; and a control unit controlling the camera unit, the triaxial driving device and the rotation driving device.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a wafer aligning apparatus and a wafer aligning method,

The present disclosure relates to a wafer alignment apparatus and a wafer alignment method.

2. Description of the Related Art [0002] In recent years, various semiconductor packages have been developed to manufacture semiconductor packages on wafers, and then to package semiconductor packages by singulating individual semiconductor packages.

In the packaging process, the wafer on which the semiconductor packages are formed is placed on the stage, and the cutting member is processed on the stage to cut the wafer in the individual semiconductive package units. The cutting member can be cut so as not to come into contact with the stage while processing the wafer so as to coincide with the cutting line of the wafer on the stage. However, in the case of a wafer having a circular shape, it is very difficult to precisely align the wafer and the stage, and therefore, when the wafer is placed on the stage, there is a high possibility that the wafer is not accurately seated on the stage.

Particularly, in the case of the conventional wafer aligning apparatus, it is judged whether or not the wafer is aligned by using a sensor member such as a laser or an infrared ray sensor. In recent years, there has been a tendency that the thickness of the wafers is becoming thinner gradually, so that the wafers that are seated on the stage are warped, and in the case of the conventional sensor type wafer aligning apparatus, the wafer is mistakenly recognized and the alignment efficiency is reduced.

The present disclosure is directed to a wafer alignment apparatus and a wafer alignment method.

A wafer alignment apparatus according to one embodiment includes a stage for seating a wafer; A rotation driving device for rotating the stage; A trigger generating device for generating a trigger signal according to an angle change according to the rotation of the stage; A camera unit for photographing an image of the wafer in accordance with the generation of a trigger signal of the trigger generator; A three-axis driving device for three-dimensionally moving the stage; And a control unit for controlling the camera unit, the three-axis driving unit, and the rotation driving unit.

The control unit may calculate the center of the wafer from the image of the edge of the wafer photographed by the camera unit, and align the center of the wafer by controlling the three-axis driving unit based on the calculated result.

The camera unit can continuously photograph an image of the edge of the wafer in a fixed state.

The controller may specify a notch or a flat of the wafer from the image of the edge of the wafer photographed by the camera unit and align the direction of the wafer by controlling the rotation driving device based on the specified result .

And a suction part for sucking the wafer to the stage.

And a temporary fixing unit for fixing the wafer when the stage moves in three dimensions.

The temporary fixation portion may include a plurality of support rods spaced apart from each other at the same angle.

A wafer alignment method according to one embodiment includes: placing a wafer on a stage; Rotating the stage according to a trigger signal generated periodically; Capturing an edge of a rotating wafer according to the trigger signal; Analyzing the photographed image to derive the center of the wafer; And aligning the wafer on the stage based on the center of the derived wafer.

After the step of seating the wafer,

And a step of adsorbing the wafer to the stage.

Wherein aligning the wafer comprises:

Moving the stage in a vertical direction to fix the wafer;

Moving the stage horizontally to align the center of the wafer with the center of the stage; And

And moving the stage vertically to seat the wafer on the stage.

Wherein the step of photographing the edge of the wafer comprises:

The image of the edge of the wafer can be continuously photographed while the camera section is fixed.

After aligning the wafer on the stage based on the derived center of the wafer,

Specifying a notch or flat of the wafer from the image of the photographed wafer edge and aligning the orientation of the wafer based on the specified result.

The wafer alignment apparatus and the wafer alignment method according to the present invention provide an easy and quick apparatus and method for aligning thin wafers such that a warp phenomenon occurs.

The wafer alignment apparatus and the wafer alignment method according to the present invention can correct and correct the center of a wafer bent by using a conventional imaging apparatus instead of using a conventional optical sensor apparatus.

1 is a schematic view of a wafer alignment apparatus according to an embodiment.
FIGS. 2 to 7 schematically illustrate a wafer alignment method according to one embodiment.

Brief Description of the Drawings The advantages and features of the present invention, and the manner of achieving them, will be apparent from and elucidated with reference to the embodiments described in conjunction with the accompanying drawings. It is to be understood, however, that the invention is not limited to the embodiments shown herein but may be embodied in many different forms and should not be construed as being limited to the preferred embodiments of the present invention. do. BRIEF DESCRIPTION OF THE DRAWINGS The above and other aspects of the present invention will become more apparent by describing in detail preferred embodiments thereof with reference to the attached drawings. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

The terminology used in this application is used only to describe a specific embodiment and is not intended to limit the invention. The singular expressions include plural expressions unless the context clearly dictates otherwise. In the present application, the terms "comprises" or "having" and the like are used to specify that there is a feature, a number, a step, an operation, an element, a component or a combination thereof described in the specification, But do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, or combinations thereof. The terms first, second, etc. may be used to describe various elements, but the elements should not be limited by the terms. The terms are used only for the purpose of distinguishing one component from another.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to the like elements throughout. .

1 is a schematic view of a wafer alignment apparatus 100 according to an embodiment. 1, the wafer aligning apparatus 100 includes a stage 111 for supporting a wafer WA, a suction unit 112, a rotation driving device 121 for driving the operation of the stage 111, And may include a temporary fixing unit 150 including a device 122, a control unit 130, a trigger generating unit 131 for generating a trigger, a camera unit 140, and a plurality of support bars 151 and 152.

The wafer WA is an object to be processed by semiconductor processing. The wafer WA may be made of a semiconductor material including silicon (Si), but the material is not limited. The shape of the wafer WA may be, for example, circular but is not limited thereto.

The stage 111 can seat the wafer WA. The shape of the stage 111 may be, for example, a cylinder shape, but is not limited thereto. The stage 111 can rotate or move in three axes (x axis, y axis, z axis). As the stage 111 moves, the wafer WA seated on the stage 111 can move together. The stage 111 can derive coordinate information for aligning the wafer WA through the rotational motion and can perform alignment of the wafer WA through the three-axis motion.

The adsorption unit 112 is connected to the stage 111 and applies pressure to the wafer WA placed thereon so that the wafer WA can be adsorbed on the stage 111. [ For example, the adsorption unit 112 may be a vacuum pump. The upper surface of the stage 111 in contact with the wafer WA can be punched for adsorption. For example, the upper surface of the stage 111 has a plurality of holes, through which the fluid is sucked into the adsorption portion 112 and can apply an adsorption pressure to the wafer WA. Whether the adsorption unit 112 is driven can be controlled by the control unit 130. For example, the adsorption unit 112 adsorbs the wafer WA to the stage 111 in the on state in the case of the rotational motion of the stage 111, and in the case of the three-axis movement of the stage 111 The wafer WA can be prevented from being attracted to the stage 111 in an off state.

The rotation driving device 121 can rotate the stage 111. [ The rotation driving device 121 may include a motor or the like connected to the stage 111 to rotate the stage 111. The rotation driving device 121 can be controlled by the control unit 130. [ For example, the rotation driving device 121 may rotate the stage 111 by 360 degrees under the control of the controller 130 when measuring the alignment state of the wafer WA. For example, when the wafer alignment of the wafer WA is completed, the rotation driving device 121 rotates the stage 111 by an appropriate angle so as to align the notch in an intended direction under the control of the control unit 130 .

The three-axis driving device 122 can move the stage 111 along three axes of x-axis, y-axis, and z-axis. The three-axis driving device 122 may include a motor, a slide unit (for example, additionally), etc., connected to the stage 111 to move the stage 111. The three-axis driving device 122 can be controlled by the control unit 130. [ For example, after the alignment state measurement of the wafer WA is completed, the three-axis driving device 122 drives the three-axis driving device 122 to align the center of the wafer WA with the center of the stage 111 under the control of the controller 130, The position of the stage 111 can be moved along three axes.

The control unit 130 may control the operation of each component of the wafer alignment apparatus 100. [ For example, the control unit 130 can control the adsorption unit 112, the rotation drive unit 121, the three-axis drive unit 122, the trigger generation unit 131, and the camera unit 140. The control unit 130 can process the image data of the wafer WA captured by the camera unit 140 and derive the center coordinates of the wafer WA. The control unit 130 controls the adsorption unit 112 and the three-axis driving unit 122 based on the center coordinates of the wafer WA and the stage 111 to detect the position of the stage 111 and the wafer WA, As shown in FIG. The control unit 130 can derive the coordinates of the notch of the wafer WA based on the image data of the wafer WA captured by the camera unit 140. [ The control unit can control the adsorption unit 112 and the rotation driving device 121 so that the notches of the wafers WA are directed in an intended direction based on the coordinates of the derived notches.

The controller 130 controls the rotation driving device 121 to rotate the stage 111 so as to have a constant angular velocity. The controller 130 controls the trigger generator 130 simultaneously with the rotation of the stage 111 to generate a trigger signal whenever the stage 111 rotates by a predetermined angle. The trigger signal generated in the trigger generating device 130 is transmitted to the camera section 140. The camera section 140 generates a camera section photographing area including the edge of the wafer WA Can be photographed.

The control unit 130 can obtain the center coordinates of the wafer WA based on the center coordinates of the stage 111, the edge coordinates obtained in the photographing of the camera unit 140, and the center coordinates of the camera region photographing region. The control unit 130 can apply a processing algorithm for deriving the center coordinates of the wafer WA, which will be described later with reference to FIG.

The controller 130 may rotate the stage 111 by 360 degrees to obtain the center coordinates of the wafer WA and rotate the stage 111 by 720 degrees or 1080 degrees to increase the accuracy. The control unit 130 may change the degree of change of the angle of the stage 111 at which the trigger generating device 130 generates the trigger signal in order to increase the speed at which the center coordinates of the wafer WA are derived. The controller 130 may change the magnitude of the angular velocity of rotation of the stage 111 to raise the velocity at which the center coordinates of the wafer WA are derived.

The trigger generator 131 can generate a trigger signal to be photographed by the camera unit 140 every time the stage 111 rotates by a predetermined angle under the control of the controller 130. [ The trigger generator 131 may be a separate component from the controller 130 or may be an internal component of the controller 130 and is not limited to a specific embodiment. The trigger generating device 131 can generate the trigger signal in consideration of the temporal delay in which the trigger signal reaches the camera section 140 and the camera section 140 actually photographs the wafer WA. Such a consideration of the temporal delay can be achieved by the control unit 130. [

The camera section 140 may be provided to form a camera section photographing area including an edge of the wafer WA. The camera unit 140 may be a normal image capturing apparatus. For example, the camera section 140 may include an imaging device in a visible light region. The camera unit 140 may be provided at a vertical upper portion with respect to the edge of the wafer WA to photograph the photographing region of the camera. The camera unit 140 can photograph the wafer WA in a fixed state. The camera unit 140 may transmit the image data photographed by the control unit 130 to the control unit 130.

The camera unit 140 can photograph the wafer WA when the trigger signal transmitted from the trigger generator 130 arrives. Through the combination of the trigger generating device 130 and the camera unit 140, it is possible to photograph the wafer WA at regular intervals without using a separate infrared sensor or laser sensor, even with a normal imaging device. In addition, since the camera section 140 forms the camera section photographing area including the edge of the wafer WA to acquire the image data, even if the wafer WA is somewhat distorted due to the thin wafer WA, The coordinates of the edge of the wafer WA can be obtained.

In the case of a conventional laser or infrared sensor, a sensor is provided so as to place the edge region of the wafer WA therebetween. However, when the wafer is bent, the edge region of the wafer easily escapes to the outside of the sensing region of the sensor, There is a disadvantage that it is not achieved. In contrast, in the case of the wafer alignment apparatus 100 according to the present invention, the center point of the wafer WA can be secured quickly and accurately irrespective of slight bending of the wafer WA while utilizing the normal camera unit 140 There is an advantage in this respect.

The temporary fixing unit 150 is a fixing member for fixing the wafer WA regardless of the movement of the stage 111. [ The temporary fixing unit 150 moves the wafer WA along the stage 111 when the control unit 130 moves the stage 111 to align the center of the wafer WA with the center of the stage 111 So that it can be fixed. For example, the temporary fixing portion 150 may include a plurality of support rods 151 and 152. The support bars 151 and 152 may be spaced apart from each other by a predetermined angle. For example, the new support rods 151 and 152 may be spaced 120 degrees apart from each other. When the stage 111 seats the wafer WA, the support bars 151 and 152 can be positioned below the wafer WA. When the stage 111 is moved vertically downward by the three-axis driving device 122 to align the wafer WA, the movement of the wafer WA is fixed by the support rods 151 and 152, Can move independently in the downward direction and then adjust the position in the plane direction. The temporary fixing unit 150 is provided below the wafer WA when the stage 111 is seated on the wafer WA and can fix the wafer WA in the case of vertical movement of the stage 111 And it is not limited to the example of the support rods 151 and 152. [ For example, the temporary fixing part 150 may be an annular support member.

FIGS. 2 to 7 schematically illustrate a wafer alignment method according to one embodiment.

The wafer alignment method according to the present embodiment

(1) placing the wafer WA on the stage 111

(2) a step of rotating the stage 111

(3) photographing the edge of the rotating wafer WA in accordance with the trigger signal

(4) deriving the center of the wafer WA by analyzing the photographed image image

(5) aligning the wafer WA on the stage 111 based on the center of the derived wafer WA.

Also,

(1) After the step of placing the wafer WA on the stage 111,

(1-2) The step of adsorbing the wafer WA to the stage 111. [

Also,

(5) aligning the wafers WA,

(5-1) moving the stage 111 in the vertical direction to fix the wafer WA;

(5-2) moving the stage 111 in the horizontal direction to align the center of the wafer WA with the center of the stage 111; And

(5-3) Moving the stage 111 in the vertical direction to seat the wafer WA on the stage 111.

Also,

(3) The step of photographing the edge of the wafer WA may be a step of successively photographing the image of the edge of the wafer WA in a state where the camera unit 140 is fixed.

Also,

(6) specifying a notch or flat of the wafer WA from the image of the edge of the photographed wafer WA, and aligning the direction of the wafer WA based on the specified result can do.

Referring to FIG. 2, the rotation driving device 121 is driven under the control of the control unit 130 to rotate the stage 111 at a constant angular velocity. For example, the control unit 130 may rotate the stage 111 by 360 degrees.

The wafer WA can be rotated together with the angular velocity of the stage 111 at the same angular velocity by the rotation of the stage 111 since the wafer WA is attracted to the stage 111 by the driving of the adsorption unit 112 . The trigger generating device 131 can generate the trigger signal every time the stage 111 rotates by a certain angle in consideration of the angular speed of the stage 111 under the control of the control section 130. [ The trigger signal is transmitted to the camera unit 140 so that the camera unit 140 can continuously photograph the edge of the wafer WA every time the wafer WA rotates by a predetermined angle. The camera unit 140 may transmit the photographed image data to the control unit 130. [

3, in a state in which the center coordinates WA_C (Wx, Wy) of the wafer and the center coordinates ST_C (X1, Y1) of the stage 111 do not coincide with each other, Can photograph the edge portion of the wafer WA rotating in the camera section photographing region. At this time, a straight line connecting the camera center coordinate (X2, Y2) and the center coordinate ST_C (X1, Y1) of the stage 111 intersects the edge of the wafer WA with the edge (X3, Y3 ). The control unit 130 can derive the center coordinates WA_C (Wx, Wy) of the wafer through processing of the image data. Hereinafter, an embodiment in which the controller 130 derives the center coordinates WA_C (Wx, Wy) of the wafer will be described.

The center coordinates ST_C (X1, Y1) of the stage 111 and the edge coordinates of the wafer WA are defined as Lr and the center coordinates ST_C (X1, Y1) of the stage 111 and the edge coordinates The length of the minor center coordinates (X2, Y2) is defined as L. Since the stage 111 rotates on the basis of ST_C (X1, Y1), ST_C (X1, Y1) is constant even in the rotation of the stage 111. [ In addition, since the camera unit 140 is fixed, the center coordinates (X2, Y2) of the camera unit are constant. Therefore, the length L of the center coordinates ST_C (X1, Y1) of the stage 111 and the center coordinates (X2, Y2) of the camera unit is a constant. That is, Y1 of the center coordinates ST_C (X1, Y1) of the stage 111 and Y2 of the camera unit center coordinates (X2, Y2) are the same. When the center coordinates (X2, Y2) of the camera unit are taken as (0, 0) from the reference coordinates, the following relationship can be satisfied.

Y1 = Y2 = Y3 = 0

The length between the center coordinates ST_C (X1, Y1) of the stage 111 and the edge coordinates of the wafer WA is (X3, Y3), and Lr is a variable that is changed in accordance with the rotation of the stage 111. Therefore, Lr may have a different value depending on the rotation angle of the stage 111. [ When the rotation angle of the stage 111 is defined as T, Lr can be expressed by Lr _T (where T is a rotation angle). For example, when the trigger generator 131 generates a trigger signal every time the stage is changed by 1 degree, the stage 111 is set to 0 degree, 1 degree, 2 degrees, 3 degrees, ... , Each time a 360 degree camera unit 140 takes a camera section photographing area, because Lr is _{Lr 1, Lr 2, Lr 3} , ... You can have 360 data sets of Lr ₃₆₀ .

When the rotation angle T is represented by the index, the wafer alignment method according to the present embodiment satisfies the following equation.

Lr _T = L - X3 _T

At this time, when the edge viewed from the vertical direction is referred to as a reference, the edge coordinates can be expressed as (Lr _T , T) by using a polar coordinate system. If this polar coordinate system is expressed by the orthogonal coordinate system, it can be expressed by the following equation.

x _T = Lr _T * cos (T)

y _T = Lr _T * sin (T)

When the planar view of the wafer WA viewed from the vertical direction is circular, the edge coordinates (x _T , y _T ) expressed in the rectangular coordinate system must satisfy the original equation.

(x _T - W x) ² + (y _T - Wy) ² = r ²

x _T ² + y _T ² - 2 Wx * x _T + 2 Wy * y _T + Wx ² + Wy ² - r ² = 0

Here Wx -2 define the coefficients of x in _T c, define 2 Wy in the y coefficient _T to d, and ² constant Wx + Wy ² - Defining the r ² to e, to the expression is satisfied .

* x + d * y _T c + _T = e - x _T ² - _T ² y

In the above equation, x _{T ,} y _T Is a matrix data having a different value according to the rotation angle T, the values of c, d, and e can be derived through the above-described matrix calculation. For example, assuming that the stage is rotated 360 degrees and the generation of the trigger signal of the trigger generator occurs every time the stage is rotated by an angle of 1 degree, T can be a natural number from 1 to 360.

[x ₁ y ₁ 1] [c] [-x ₁ ² - y ₁ ² ]

[x ₂ y ₂ 1] [d] = [-x ₂ ² - y ₂ ² ]

[x ₃₆₀ y ₃₆₀ 1] [e] = [-x ₃₆₀ ² - y ₃₆₀ ² ]

Through the matrix operation, variables c, d, and e can be derived, and Wx and Wy, which are the center coordinates of the actual wafer, can be derived.

The above calculation assumes that the shape of the wafer WA seen from above is also circular, even if a warping phenomenon occurs due to the thinness of the circular wafer WA. The simulation results and the experimental results show that the warp shape of the wafer WA having a thickness of 200um or less appears as a circular shape so that the center coordinates Wx and Wy of the wafer WA of the controller 130 are calculated quickly and accurately .

However, the present invention is not limited to this embodiment. When the shape of the wafer WA seen from above is an ellipse, the center coordinates Wx and Wy of the wafer WA can be derived using the elliptic function have. In addition, the center coordinates Wx, Wy of the wafer WA can be derived by using a function representing the warped shape of the wafer WA seen from above.

Referring to FIGS. 4 to 6, the controller 130 may control the components to match the center coordinates (Wx, Wy) of the derived wafer with the center coordinates (X1, Y1) of the stage.

Referring to FIG. 4, the controller 130 may move the stage 111 in the z-axis direction by controlling the three-axis driving device 122. At this time, the wafer WA is fixed by the temporary fixing portion 150, and may not move integrally with the stage 111. [

5, the control unit 130 controls the three-axis driving unit 122 to move the stage in the x-axis and y-axis directions so that the center coordinates (Wx, Wy) of the wafer WA and the center coordinates (X1, Y1) can be matched.

6, the control unit 130 controls the three-axis driving device 122 to move the stage 111 in the z-axis direction so that the center coordinates (Wx, Wy) of the wafer and the center coordinates The stage 111 and the wafer WA can be sucked again in a state in which the X1 and Y1 coincide with each other. For example, the three-axis driving device 122 can lift the stage 111 to separate the wafer WA from the temporary driving unit 150. [ For example, the three-axis driving device 122 can control the adsorption unit 112 to adsorb the stage 111 and the wafer WA.

Referring to FIG. 7, the controller 130 controls the rotation driving device 121 to rotate the stage 111. The controller 130 may rotate the stage 111 by an intended angle so that the notches or flats on the surface of the wafer WA are aligned in the intended direction.

It will be understood by those skilled in the art that the foregoing description of the present invention is for illustrative purposes only and that those of ordinary skill in the art can readily understand that various changes and modifications may be made without departing from the spirit or essential characteristics of the present invention. will be. It is therefore to be understood that the above-described embodiments are illustrative in all aspects and not restrictive. For example, each component described as a single entity may be distributed and implemented, and components described as being distributed may also be implemented in a combined form.

The scope of the present invention is defined by the appended claims rather than the detailed description and all changes or modifications derived from the meaning and scope of the claims and their equivalents are to be construed as being included within the scope of the present invention do.

100: Wafer alignment device
111: stage
121: Rotary driving device
122: 3-axis drive unit
112:
130:
131: Trigger generator
140:
150:
151, 152:

Claims (12)

A stage for placing the wafer thereon;
A rotation driving device for rotating the stage;
A trigger generating device for generating a trigger signal according to an angle change according to the rotation of the stage;
A camera unit for photographing an image of the wafer in accordance with the generation of a trigger signal of the trigger generator;
A three-axis driving device for three-dimensionally moving the stage; And
And a control unit for controlling the camera unit, the three-axis driving unit, and the rotation driving unit. The method according to claim 1,
Wherein the control unit calculates the center of the wafer from the image of the edge of the wafer taken by the camera unit and aligns the center of the wafer by controlling the three-axis driving unit based on the calculated result. 3. The method of claim 2,
Wherein the camera section continuously photographs an image of a wafer edge in a fixed state. The method according to claim 1,
Wherein the control unit specifies a notch or a flat of the wafer from the image of the edge of the wafer photographed by the camera unit and controls the rotation driving device based on the specified result to perform wafer alignment Device. The method according to claim 1,
And a suction part for sucking the wafer onto the stage. The method according to claim 1,
And a temporary fixing section for fixing the wafer when the stage moves. The method according to claim 6,
Wherein the temporary fixing portion includes a plurality of support rods spaced from each other at the same angle. Placing the wafer on a stage;
Rotating the stage at a constant angular velocity;
Photographing an edge of a rotating wafer according to a trigger signal generated periodically;
Analyzing the photographed image to derive the center of the wafer; And
And aligning the wafer on the stage based on the center of the derived wafer. 9. The method of claim 8,
After the step of seating the wafer,
And adsorbing the wafer to the stage. 9. The method of claim 8,
Wherein aligning the wafer comprises:
Moving the stage in a vertical direction to fix the wafer;
Moving the stage horizontally to align the center of the wafer with the center of the stage; And
And moving the stage in a vertical direction to seat the wafer on the stage. 9. The method of claim 8,
Wherein the step of photographing the edge of the wafer comprises:
A method of aligning a wafer in which an image of a wafer edge is continuously photographed while a camera section is fixed. 9. The method of claim 8,
After aligning the wafer on the stage based on the derived center of the wafer,
Identifying a notch or flat of the wafer from the image of the photographed wafer edge and aligning the orientation of the wafer based on the specified result.

Images