JPH053153A - Exposing device for unnecessary resist on wafer - Google Patents

Abstract

PURPOSE:To obtain a device capable of performing a desired exposure on a wafer even if the wafer is arranged in any direction by a method wherein the device is provided with a rotating means, a peripheral edge detecting means, a driving means, a placement state detecting means, an exposure start state setting means, an exposure start state verifying means, a light radiation means, an exposure region setting means and the like, which are respectively specified. CONSTITUTION:The title device is provided with a rotating means 1 provided with a rotating stand 2 to be placed with a wafer W, a peripheral edge detecting sensor 3 for detecting the peripheral edge WA of the wafer W which is rotated, a peripheral edge detecting sensor driving means 4 to move the sensor 3 in such a way that the sensor 3 is always positioned on the peripheral edge WA of the wafer W and a placement state detecting means 5 for detecting the placed state of the wafer W by the movement of the sensor 3. Moreover, the device is provided with an exposure start state setting means 6 for positioning the wafer W to a prescribed direction, an exposure start state verifying means 10 for verifying the position subsequent to the movement of the wafer W to the prescribed direction, a light radiation means 7, an exposure region setting means 8 and a moving means 9 for moving the means 7 while the means 7 is controlled.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an unnecessary resist exposure apparatus required for removing an unnecessary resist on a wafer in a developing process.

[0002]

2. Description of the Related Art In the manufacturing process of ICs, LSIs, etc., for example, a resist is applied to the surface of a semiconductor wafer such as a silicon wafer, then a circuit pattern is exposed, and this is developed to form a resist pattern. It is being appreciated.
The resist is usually applied by a spin coating method in which the wafer is rotated while pouring the resist on the central position of the wafer surface and the resist is applied to the entire surface of the wafer by centrifugal force. Therefore, the resist is also applied to the peripheral portion of the wafer.

However, the peripheral portion of the wafer is rarely used as a pattern formation area. This is because when a wafer is subjected to various kinds of processing steps, it is often transported and held by utilizing the peripheral portion of the wafer, and pattern distortion easily occurs in the peripheral portion, resulting in poor yield. Therefore, when the resist is a positive type resist, the peripheral portion is not exposed, and therefore the resist remains in the peripheral portion even after development, and this resist contaminates peripheral equipment during the transportation and holding of the wafer, and thus the wafer surface. This was a cause of contamination, which caused a decrease in yield. Therefore, recently, in order to remove the unnecessary resist in the peripheral portion in the developing step, so-called peripheral exposure is performed in which the unnecessary resist in the peripheral portion is exposed separately from the exposure step of the circuit pattern in the pattern formation region. In this peripheral exposure, the light guided by the optical fiber is applied to the peripheral portion in a spot-like manner.

On the other hand, in recent years, the surface of a wafer is often divided by a successive movement type reduction projection exposure apparatus (stepper) like a substrate and subjected to successive exposure. In this case, the shape of the peripheral portion where the circuit pattern for one chip cannot be correctly exposed becomes a stepped shape, and its size and shape change variously every time it is exposed.
Further, since the wafer is provided with a linear peripheral portion called an orientation flat (hereinafter, simply referred to as an orientation flat) which usually indicates a crystal direction, it is not a perfect circle. Under these circumstances, when exposing the unnecessary resist around the wafer in a stepwise manner, it is necessary to detect how the wafer is mounted on the rotary table before the exposure is started. is there. In particular, if the position of a singular point such as orientation flat is not known, the reference point for stepwise exposure becomes unknown. As a method of detecting the direction of a singular point on such a turntable, there is, for example, Japanese Patent Application No. 2-243491.

A method of detecting an orientation flat as a singular point will be described with reference to FIG. 1 is a wafer rotating means,
A rotary table 2 having a built-in motor and having a peripheral edge WA and on which a wafer W having a surface coated with a resist is mounted is provided. Reference numeral 3 denotes a peripheral edge detection sensor, which detects the peripheral edge WA of the rotating wafer W. This peripheral detection sensor 3
Is provided with a light emitter and a light receiver, and moves in the direction of arrow A so as to be always located at the peripheral edge according to the amount of light from the light emitter detected by the light receiver. This control is, for example, using a comparator to perform feedback control with respect to the reference light amount. Reference numeral 4 denotes a peripheral edge detection sensor driving means, which is composed of a servo motor or the like, although not shown. Reference numeral 5 denotes a mounting state detecting means, which detects the mounting state of the wafer W on the rotary table 2 by moving the peripheral edge detection sensor 3. The mounting state detection means 5 includes a position detection means, a rotation angle reading means, and a storage means.

The position detecting means detects how much the peripheral edge detecting sensor 3 has moved in the direction of the arrow A, and the rotation angle reading means detects the rotation angle of the wafer W at that time. By accumulating the information in the storage means, it is possible to store the information of all the peripheral positions. Particularly, in the orientation flat WF, the movement of the peripheral edge detection sensor 3 is large, so that it can be easily detected. Then, after the wafer W is rotated once, the exposure start state setting means 6 rotates the wafer W so that the orientation flat WF is positioned at a predetermined reference position, and the state is initially started in the peripheral exposure process of the wafer W. After that, the unnecessary resist in the peripheral portion can be exposed stepwise by an optical fiber (not shown). With such a configuration, a desired stepwise exposure can be achieved regardless of the orientation of the wafer (wherever the orientation flat is located).

[0007]

As described above, in the conventional unnecessary resist exposure technique, the peripheral edge of the wafer is detected while moving the peripheral edge detection sensor in the radial direction of the wafer. Edge detection sensor 3 accumulated in the storage means at this time
FIG. 5 shows the relationship between the position information and the rotation angle information. The horizontal axis is the rotation angle of the wafer W, and the vertical axis is the peripheral edge detection sensor 3
Is the amount of displacement of the position. As shown in FIG. 5, a region F in which the displacement amount is largely changed between the + side and the − side is an angular range in which the peripheral edge detection sensor 3 detects the orientation flat WF.
Further, a point Θ ₀ where the displacement amount is 0 in the region F indicates a state in which the peripheral edge detection sensor 3 is closest to the rotation center side when the orientation flat WF is detected. However, as shown in FIG. 5, the change in the displacement amount always includes a sawtooth error. This is because the peripheral edge detection sensor driving means 4 follows and controls the peripheral edge detection sensor 3 according to the detection amount of the light receiver to move the peripheral edge detection sensor 3, but the tip of the arm having the light emitter and the light receiver always vibrates slightly. Is because For this reason,
The information stored in the storage means causes the exposure start state setting means 6 to operate, and when the wafer W is rotated to the initial start state, the above-described error influences the position setting with a slight deviation. If stepwise exposure of the peripheral portion is performed in such a state, desired exposure will not be performed.
The present invention aims to solve the above problems.

[0008]

In order to solve the above-mentioned problems, an unnecessary resist exposure apparatus for a wafer according to the present invention is a wafer having a singular point such as an orientation flat on the periphery and a wafer whose surface is coated with a resist. Wafer rotating means having a rotating table mounted thereon, a peripheral edge detecting sensor for detecting a peripheral edge of a rotating wafer, and a peripheral edge detecting sensor moved in a radial direction of rotation of the wafer rotating means so as to be always located on the peripheral edge of the wafer. The edge detection sensor driving means for causing the wafer to move, and the placement state detection means for detecting the placement state of the wafer on the rotary table by the radial movement of the edge detection sensor, and the signal from the placement state detection means to receive the wafer. An exposure start state setting means for setting a position in a predetermined direction with a singular point as a reference, and an exposure start state for confirming the position after the wafer is moved in a predetermined direction by the exposure start state setting means. And confirmation means, a light irradiating means for exposing the surface of the resist on the wafer in the spot, the exposure area setting means for presetting the area to be exposed in the resist,
It is characterized by comprising moving means for controlling the movement of the light irradiation means on the surface of the wafer.

[0009]

The unnecessary resist exposure apparatus on the wafer of the present invention is
Even if the placement state detection means causes a positional deviation of the exposure start state of the wafer, it can be corrected by the exposure start state confirmation means.

[0010]

EXAMPLES The present invention will be described below with reference to examples. FIG. 1 shows an embodiment of an unnecessary resist exposure apparatus on a wafer according to the present invention. Description of the same reference numerals as those in FIG. 4 will be omitted. 6 is an exposure start state setting means,
Obtaining the orientation information of the orientation flat WF, the wafer W is oriented to the orientation flat W.
It is set in a predetermined direction with F as a reference. Therefore, when performing stepwise exposure on the unnecessary resist in the peripheral portion of the wafer, it is necessary to always set the orientation flat at a predetermined position. The rotation direction for this direction may be forward rotation or reverse rotation. Reference numeral 7 denotes a light irradiating means for spot-wise exposing the unnecessary resist around the wafer. As shown in FIG. 1, the light irradiation means 7 includes a lamp 71 and an elliptical focusing mirror 7 that collects and reflects the light from the lamp 71.
2, a reflecting mirror 73 that reflects the light from the elliptical focusing mirror 72 in the horizontal direction, a shutter 74 that is arranged so as to be able to enter and exit the outgoing optical path of the reflecting mirror 73, and a light that guides the light from the reflecting mirror 73. And a fiber 75. Reference numeral 8 denotes an exposure area setting means, which presets an area of the resist to be exposed, and an IC memory or the like is used. Reference numeral 9 denotes a moving means for controlling the movement of the light irradiation means 7 on the surface of the wafer W. As shown in FIG. 1, the moving means 9 has an instruction arm 91 for holding the emitting end of the optical fiber 75 of the light irradiation means 7, an X table 92, and a Y table 93.
And a stepping motor 94 for reciprocating the X table in the X direction and a stepping motor 95 for reciprocating the Y table in the Y direction. The support arm 91 is attached to the Y table 93. Y
The direction is a direction from the emitting end toward the rotation center of the turntable 2, and the X direction is a direction perpendicular to the Y direction. Therefore, the emitting end of the optical fiber 75 moves to the X table 92 and the Y table 93 to move around the wafer.

Reference numeral 10 is an exposure start state confirmation means. In this method, the exposure start state setting means 6 directs the orientation flat WF in a predetermined direction and then corrects a slight deviation.
As the exposure start state confirmation means 10, a device in which CDDs are arranged toward the wafer W is applied. The wafer 11 receives the detection signal from the exposure start state confirmation means 10 and receives the wafer W.
Is a calculating means for sending a signal to the rotating means 1 to rotate the. Next, the operation of the exposure start state confirmation means 10 will be described with reference to FIG. (A) is the mounting state detection means 5
Shows the state after the mounting state of the wafer W on the turntable 2 is detected. From the state in which the orientation flat WF is present at this arbitrary position, the wafer W is set by the exposure start state setting means 6.
Rotate in the direction of Θ ₁ to set it in place.
However, the orientation flat WF is slightly displaced from the position WF1 (the state indicated by the dotted line) which should be originally arranged due to the error in the detection of the peripheral edge detection sensor 3 as described above.
It is located at F2. This state is shown in (b). The exposure start state confirmation means 10 is composed of two rod-shaped detectors 10A and 10B having a sensor such as a CCD embedded therein and extending toward the center of the wafer W. Then, by detecting the edge of the orientation flat WF in each of the detectors, it is possible to determine to what extent the calculation means 11 deviates from the position originally supposed to be arranged. And
By rotating the wafer W again by the rotating means 1 so as to correct the deviation, the orientation flat WF is arranged at the correct position. This state is shown in (C). Next, the optical fiber 75, which is the light irradiation means 7, moves on the wafer W and exposes the peripheral edge of the wafer W step by step.

Next, an exposure method by the unnecessary resist exposure apparatus of the present invention will be described. The exposure area setting means 8 sets the exposure area of the unnecessary resist on the wafer W. The exposure area is determined based on the formation area H as shown in FIG. The wafer W mounted on the rotary table 2 is rotated once, and the mounting state detecting means 5 detects the mounting state at this time, particularly the position of the orientation flat WF. The exposure start state setting means 6 positions the wafer W in the exposure start state with reference to the orientation flat WF. Next, the exposure start state confirmation means 10 detects a slight shift that occurs when the orientation flat WF is set in position, and corrects it. Next, the moving means 9 moves the emitting end of the optical fiber 75 of the light irradiation means 7 to start the exposure of the unnecessary resist on the wafer W. The emission end of the optical fiber 75 is the exposure start point, as shown in FIG.
Of the wafer W when it is set to the position for exposing point a of
With the shutter stopped, the shutter 74 is opened to irradiate light from the emission end, and the emission end of the optical fiber 75 is moved by the moving means 9 in the X direction toward the position to be exposed, so that the point a to the point b. Exposure according to. Then, while moving the emitting end of the optical fiber 75 in the Y direction by the moving means 9 from the position where the point b is exposed, light is emitted from the emitting end to the position where the point c is exposed. Furthermore, c
From the position where the point is exposed, the optical fiber 7 is moved by the moving means 9.
While moving the emitting end 5 in the X direction, light is irradiated from the emitting end up to the position where the point d is exposed for exposure.

When the exposure is completed up to the position of point d in this way, the wafer rotating means 1 is used to rotate the rotary table 2 with the shutter 74 temporarily closed in order to prevent the pattern forming area H from being exposed by mistake. Is rotated by 90 ° and the wafer W is rotated by ¼. When the wafer W has rotated 1/4, the exposure is performed stepwise from the position at which point d is exposed in the same manner as above, with the wafer W stopped. As described above, the wafer W is exposed to the stepwise exposure 4 times every quarter rotation.
When it is performed once, the exposure of the entire circumference of the peripheral portion of the wafer W is finished.

Next, the exposure start state confirmation means 10 of the present invention.
Another embodiment will be described. After the orientation flat WF of the wafer W is arranged at a predetermined position by the exposure start state setting means 6, as shown in FIG. 6, an optical fiber 7 which is a light irradiation means 7.
5 moves as shown by arrows a → b → c. At this time, the shutter 74 is closed so that the wafer W is not exposed.
As shown in, a sensor including a light emitter 61 and a light receiver 62 is attached. The light emitter 61 is an optical fiber 75.
Of the support arm 9 while the receiver 62 is attached to the tip of the
By the dedicated arm connected to 1, the relationship between the light emitter 61 and the light receiver 62 is formed so as to be perpendicular to the exposure surface of the wafer W. When the tip of the optical fiber is moved by the X table 92, the stepping motor 94, the Y table 93, and the stepping motor 95 as described above, the light emitter 61 and the light receiver 6 are moved.
By the light detection according to 2, it is possible to know the positional deviation of the orientation flat WF. More specifically, by detecting the time when the amount of light detected by the light receiver 62 changes when the tip of the optical fiber 75 moves to the arrow a and the time when the amount of light changes when moving to the arrow c. , It is possible to know the displacement of the orientation flat WF. The data is processed by the calculation means 11 and the rotation means 1
Thus, the orientation flat WF can be set at a desired position.

In the present embodiment, as a means for detecting the mounting state of the wafer mounted on the rotary table, the orientation flat at the peripheral edge of the wafer is detected, but this is not limited to the orientation flat. Any other material having a unique shape in the peripheral portion can be similarly implemented.

[0016]

As described above, according to the present invention,
In order to expose the unnecessary resist on the peripheral portion of the wafer, no matter what state the wafer is placed on the rotating table, it is possible to surely move the orientation of the wafer to the exposure start state before performing the exposure.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing an outline of an unnecessary resist exposure apparatus according to an embodiment.

FIG. 2 is an explanatory diagram of an exposure start state confirmation means according to the present embodiment.

FIG. 3 is an explanatory diagram of a pattern formation region of a wafer in an example.

FIG. 4 is an explanatory diagram showing wafer edge detection in the present embodiment and a conventional example.

FIG. 5 is an explanatory diagram of singular points of a wafer in an example.

FIG. 6 is an explanatory view showing another embodiment of the exposure start state confirmation means according to the present embodiment.

FIG. 7 is an explanatory diagram showing another embodiment of the exposure start state confirmation means according to the present embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Rotation means 2 Rotation table 3 Edge detection sensor 4 Edge detection sensor drive means 5 Mounting state detection means 6 Exposure start state setting means 7 Light irradiation means 8 Exposure area setting means 9 Moving means 10 Exposure start state confirmation means 11 Computing means W Wafer WA Edge of wafer WF Orifla

Claims (1)

Claim: What is claimed is: 1. A wafer rotating means having a rotary table having a singular point such as an orientation flat on a peripheral edge thereof, on which a wafer coated with a resist is placed, and a peripheral edge of the rotating wafer. A peripheral edge detection sensor for detecting the wafer edge, a peripheral edge detection sensor driving means for moving the peripheral edge detection sensor in the radial direction of rotation of the wafer rotating means so that the peripheral edge detection sensor is always positioned on the peripheral edge of the wafer, and a radial movement of the peripheral edge detection sensor for the wafer Mounting state detecting means for detecting the mounting state on the rotating table, and exposure start state setting means for receiving the signal from the mounting state detecting means and setting the wafer in a predetermined direction with the singular point as a reference. An exposure start state confirmation means for confirming the position of the wafer after the wafer is moved in a predetermined direction by the exposure start state setting means, and a light irradiation hand for spotwise exposing the surface of the resist on the wafer. An unnecessary resist exposure apparatus on a wafer, comprising: a step, an exposure area setting means for setting an area of the resist to be exposed in advance, and a moving means for moving and controlling the light irradiation means on the surface of the wafer.