JPH01132124A - Exposure method and apparatus thereof - Google Patents

Abstract

PURPOSE:To make it possible to apply an exposure treatment to an object to be treated with a high yield by detecting the circumferential periphery of the object, determining from the detected periphery a predefined exposure region of the periphery of the object, and applying a light to the exposure region, thereby preventing foreign objects such as resist from being produced and unsharpness due to out-of-focus. CONSTITUTION:The circumferential periphery of an object 3 to be treated is detected. Then, a predefined exposure region of the periphery of the object 3 is determined from the detected periphery to apply a light to the exposure region. An exposing apparatus comprises a mount stage 2 for mounting the object 3 to be treated, a rotating mechanism 1 for rotating the mount base 2 at a predetermined speed, a light projector 11 facing the surface of the mount base 2, means for controlling the intensity of the light to be projected onto the object to be treated 3 from the light projector 11, a movable mechanism 12 for reciprocally moving the light projector 11 along a virtual line passing through the center of the surface of the mount stage 2, and means 14 for controlling the number of revolutions of the mount stage 2 according to the quantity of the projected light from the light projector 11. Further, for instance, means 8 for detecting the end face of the object 3 is provided near the mount stage 2.

Description

[Detailed description of the invention] [Purpose of the invention] (Industrial application field) The present invention relates to an exposure method and apparatus.

(Prior Art) In general, a lithography process, which is one of the manufacturing processes of semiconductor devices, is mainly divided into five steps: surface treatment, resist coating, exposure, development, and etching. The projection exposure equipment, etching, and other vacuum equipment used in these processes employ a mechanical method of clamping the periphery of the wafer as a method of transporting the semiconductor wafer and fixing it to the processing table.

However, if the post-processing in the previous resist coating step is insufficient, resist and the like may remain on the outer peripheral edge of the semiconductor wafer. In such a case, when the semiconductor wafer is transported, resist peeling occurs and foreign matter is likely to be generated.

As a means to prevent the generation of such foreign substances,
No. 37706, JP-A-55-12750, JP-A-58
-58731, JP 58-191434, JP 60-94660, JP 61-111151, JP 61-121333.

Side rinse disclosed in JP-A No. 61-184824, etc., JP-A-58-200537, Utility Model Application No. 58-81
No. 932, Utility Model Application No. 59-67930, JP-A No. 60-1
No. 10118, JP-A-60-121719, JP-A-6
There are backside cleaning methods disclosed in Japanese Patent Application Laid-Open No. 0-189937, Japanese Patent Application Laid-open No. 61-239625, and the like. In these methods, a solvent is sprayed onto the outer peripheral edge of the rotating wafer after the resist is applied.

This removes the resist and the like on the outer peripheral edge of the wafer.

(Problem to be Solved by the Invention) However, the above-mentioned side rinse and backside cleaning are performed while rotating the wafer.

It is not possible to selectively perform treatments such as side rinsing on the orientation flat portion. Therefore, when removing the resist at the orientation flat portion, it is necessary to increase the entire area from which the resist is removed. Therefore, the number of semiconductor chips that can be manufactured at one time is reduced. Then, there was a problem that the yield decreased. Moreover, the resist at the boundary portion where the resist is removed rises. For this reason, in an apparatus in which a plurality of points outside the exposure area are targeted for focusing, there is a problem of causing out of focus. Therefore, in order to perform the same treatment on the orientation flat and other ends as on the other ends, Japanese Patent Laid-Open Nos. 59-117123 and 61-61
A method of bringing a porous member containing a solvent into contact with the circumferential surface of a semiconductor wafer, as disclosed in Japanese Patent No. 219135, has been developed. However, these methods have not yet been able to solve problems such as out-of-focus.

In addition, in order to solve the problem of out-of-focus,
No. 535, JP-A-61-73330, U.S. Pat. No. 60-9
As disclosed in Japanese Patent Application No. 4661, etc., there is a method using an exposure means to remove a resist layer on the outer periphery of a semiconductor wafer in an annular shape. In this method, the problem of removing the resist from the orientation flat portion remains unsolved.

Therefore, as a method for solving the problem of resist removal at the orientation flat portion and the problem of out-of-focus, there is the following copying cam method. That is, in this method, the wafer is first positioned and then adsorbed onto a chuck whose rotating shaft is equipped with a cam having the same shape as the semiconductor wafer. Next, the wafer is rotated with an exposure light source guided by an optical fiber or the like tracing the cam. This exposes the periphery of the wafer. This method requires a cam that matches the shape of the wafer. Furthermore, the cam must be replaced depending on the type of wafer, which hinders automation (FA). Further, foreign matter is generated due to wear of the cam. In other words, there was a problem in that foreign matter other than the resist was generated.

The present invention has been made in response to the above-mentioned problems, and it is possible to prevent the generation of foreign substances such as resist, prevent defocusing, and achieve high yields without being affected by the shape of the processed object. It is an object of the present invention to provide an exposure method and apparatus that can perform exposure processing on the subject.

[Structure of the invention]

(Means for Solving the Problems) The present invention includes a step of detecting the outer peripheral edge of the object to be processed, and a step of determining a predetermined exposure area on the periphery of the object to be processed from the outer edge detected in this step. and a step of irradiating the exposure area with light.

The present invention also provides a mounting table on which an object to be processed is placed, a rotation mechanism for rotating the mounting table at a predetermined rotational speed, and a light irradiator provided opposite to the mounting surface of the mounting table. a light amount control means for controlling the amount of light irradiated from the light irradiator to the object to be processed; a movable mechanism that reciprocates the light irradiator along a virtual straight line passing through the center of the placement surface; The present invention provides an exposure apparatus including a rotation speed control means for controlling the rotation speed of the mounting table according to the amount of light irradiated from the light irradiation body.

(Effects) That is, the present invention can vary the rotational speed of the object to be processed, or directly change the amount of light itself when exposing the object to be processed. Thereby, it is possible to expose a specific area of the peripheral portion of the object to be processed with an arbitrary amount of light. As a result, an irregularly shaped portion of the object to be processed, such as an orientation flat portion, can be exposed with the optimum amount of light in the same manner as other peripheral portions.

By developing and cleaning the exposed portion after this exposure, for example, the resist film in that portion can be reliably removed. As a result, local swelling of the resist film can be prevented, and defocus can be prevented. Therefore, a clean and fine pattern can be easily formed on a semiconductor wafer or the like.

(Example) Hereinafter, an example in which the exposure method and exposure apparatus of the present invention are applied to a side rinsing process and a back surface cleaning process in the manufacture of semiconductor devices will be described with reference to the drawings.

FIG. 1A is an explanatory diagram showing the configuration of an example of an exposure apparatus for carrying out the exposure method of the present invention. 1 in FIG. It is. The rotation mechanism 1 includes, for example, a stepping motor whose rotation angle can be pulse-controlled. At the top of the rotating mechanism 1.

A disc-shaped mounting table 2 connected to a rotating shaft and hermetically sealed inside a container (not shown) is provided.

As shown in FIG. 2, the mounting table 2 is configured such that an object to be processed is fixed by suction through a suction hole 4 in the center. The object to be processed is, for example, a semiconductor wafer 3 having an orientation flat. An end face detection means 8 is provided near the mounting table 2 in order to identify the peripheral portion of the semiconductor wafer 3 placed on the mounting table 2 that requires side rinsing or backside cleaning.

That is, so that the outer peripheral end surface of the semiconductor wafer 3 can be detected,
A sensor light source 5 is provided on one side (for example, the bottom side) of the semiconductor wafer 3. The sensor light source 5 is composed of, for example, LEDs arranged in the negative dimension. An optical sensor 7 is provided on the other side of the semiconductor wafer 3 with a lens 6 interposed therebetween. The optical sensor 7 is a solid-state image sensor, for example, a CCD (C
It is composed of a one-dimensional sensor using a harge coupled device.

These sensor light sources 5 and the like constitute end face detection means 8.

Further, the exposure section 9 for side rinsing or back surface cleaning is configured as follows. That is, the light irradiator 11 is provided so as to face the mounting surface of the mounting table 2 . The light irradiator 11 is guided by a movable mechanism 12 to reciprocate. The movable mechanism 12 is arranged above the mounting table 2 along a straight line passing through the center of rotation of the semiconductor wafer 3. The light irradiator 11 includes a light pipe 10 such as an optical glass fiber or a liquid fiber (ULTRA FINE T
ECHNOLOGY (product name) is connected. Exposure light, such as UV light, is guided into the light pipe 10 from a light source (not shown).

A light emitting section 101 is provided at the tip of the light pipe 10, as shown in FIG. 1B. That is, the light pipe 1
A cylindrical, e.g., rectangular, airtight container 102 is connected to the tip of the tube 10, and a rectangular aperture, e.g., a rectangular aperture 103, is provided in this container 11102 coaxially with the output optical path of the light pipe 10. A diaphragm 104 is provided.

An optical lens 105.10 is provided on the optical path passing through this aperture 104.
6 are arranged and configured to converge on the surface of the semiconductor wafer 3. In order to prevent the reflected light generated by the irradiation of the wafer 3 from entering the light emitting section 101, that is, to prevent flare, a ring skirt 107 is coupled to the end of the light emitting section 101 to emit the light. A section 101 is configured. The inner wall surface of this light emitting section 101 is preferably a black surface.

The movable mechanism 12 is provided with, for example, a ball screw. A drive mechanism 13 that transmits rotational drive to the movable mechanism 12 via this ball screw will be provided. The drive mechanism 13 is 1
For example, it is driven by a stepping motor that is pulse controlled. The exposure section 9 is constituted by these light irradiators 11 and the like.

Of course, it is also possible to arrange the end face detection means 8 and the exposure section 9 at the same position. In this case, the operations of the edge face detection means 8 and the exposure section 9, which have the effect of improving throughput, are controlled by the control section 14 shown in FIG. 3 by transmitting and receiving predetermined command signals and detection signals. ing.

Next, a method of exposing the outer periphery of the semiconductor wafer 3 using an exposure apparatus will be described. Note that the process flow of the exposure method is as shown in FIG.

First, the semiconductor wafer 3 is carried onto the mounting table 2 by a transport mechanism (not shown), for example, a handling arm. A resist is applied to the surface of the semiconductor wafer 3 by, for example, a spin code in a previous process. semiconductor wafer 3
is positioned so that its center is coaxial with the rotation axis of the mounting table 2.

At this time, the semiconductor wafer 3 is suctioned onto the mounting table 2 through the suction hole 4 of the mounting table 2 using vacuum air from a vacuum generator or the like.

Then, exposure processing is started in the first order by a signal from the control section 14.

First, the mounting table 2 is rotated by the rotation mechanism 1, and the semiconductor wafer 3 is rotated at a predetermined number of rotations, for example, 10 seconds to 60 seconds per rotation. This rotation speed is appropriately selected depending on the light source.

The rotation mechanism 1 of the mounting table 2 is driven by, for example, a stepping motor whose rotation angle is pulse-controlled. The optical sensor 7 (for example, a CCD image sensor) of the end face detection section 8 is scanned in synchronization with each step of the stepping motor. Due to the operation of this end face detection section 8,
The distance of a predetermined peripheral edge exposure portion from the outer peripheral end face of the semiconductor wafer 3 is detected.

Here, the optical sensor 7 is fixed at a desired position across the peripheral edge of the semiconductor wafer 3. The output signal from the optical sensor 7 is obtained as a voltage level difference proportional to the position from the outer peripheral end surface of the semiconductor wafer 3. Based on this output signal, the control unit 14 calculates the distance of the exposure area from the outer peripheral end face of the semiconductor wafer 3 to a predetermined position. In this case, the sensor light source 5 is for increasing the contrast of the output signal of the optical sensor 7. Therefore, the sensor light source 5 is
-It may be a dimensionally arranged LED or a surface light source.

Further, if the sensitivity of the optical sensor 7 is high, it is not necessary to turn on the light. Further, the lens 6 is used to widen the detection width of the optical sensor 7. Therefore, it does not need to be used when the size difference between the objects to be processed is not very large.Here, if a CCD image sensor, which is a solid-state image sensor, is used as the optical sensor 7, the object to be processed may be Even if it is a light-transmissive type such as glass, it has high sensitivity, so it has the effect of being able to detect even the slightest difference in light amount.

Then, the calculated information on the outer peripheral end face of the semiconductor wafer 3 is stored in a storage element (not shown) in the control unit 14. From this stored information, the processing width of exposure required for a predetermined side rinse or back surface cleaning is calculated. Based on this calculation result, the light irradiation position by the exposure section 9 is controlled. That is, light is guided from a light source (not shown) to the light irradiator 11 through the light conduit 10. As the exposure light from the light source, for example, light from an ultraviolet lamp such as a mercury lamp or a xenon lamp is used. The light irradiation position is determined based on information stored in the storage element. That is.

For side rinsing or back surface cleaning on the semiconductor wafer 3, a signal calculating a desired portion to be exposed is supplied from the memory element to the control unit 14. Based on this signal, the control unit 14 controls the operations of the movable mechanism 12 and the drive mechanism 13. In this way, a predetermined area is exposed to light based on the relative drive of the semiconductor wafer 3, which is a processing object, and the light irradiation object 11. For example, the semiconductor wafer 3 is rotated on the mounting table 2 with the rotation axis fixed. In this state, exposure is performed continuously at each step by the step motor. As a result, the orientation flat portion of the semiconductor wafer 3 can be processed with a predetermined exposure area secured in the same manner as other peripheral portions. The irradiation conditions for peripheral exposure at this time are shown in FIGS. 1C, D, E, and F.

That is, the ultraviolet rays from the optical conduit lO are transmitted to the optical lens tOS, where the light beam 107 in the shape of the rectangular aperture 103 of the aperture 104 is transmitted.

It is focused at 106 and emitted to an area automatically set by the above-mentioned means on the semiconductor wafer 3.

At this time, an enlarged view of the outer peripheral end face portion of the semiconductor wafer 3 will be described with reference to the drawings.

The illumination light pattern emitted from the light emitting section 101 to the semiconductor wafer 3 has the shape of the aperture 103 of the aperture 104, that is, the rectangle shown in FIG. 1E.

As a specific example of illumination at this time, a method of irradiating only the edge of the wafer as shown in FIG.

Practically speaking, it is preferable to set the light beam at a position where the outer peripheral end face crosses the center part as shown in Fig. Considering that the illumination intensity of the light becomes low, it is desirable to have a light beam having a shape without an angular part as shown in FIG. 1F.

Of course, this deformation may also be done as long as it has an approximately rectangular shape, such as an elliptical spot. This shape of the light beam has the effect of realizing uniform peripheral exposure.

In addition, in FIGS. 1C and 1D, the edge portions protruding in a triangular shape are exaggerated illustrations of the actual circumferential end cross section of the sea urchin.

Thereafter, when the desired exposure is completed, the semiconductor wafer 3 is carried out by a transport mechanism (not shown), and the exposure process is completed. The semiconductor wafer 3 that has been carried out is subjected to development and cleaning of the exposed peripheral edge resist by a processing device (not shown) in the next step. In this embodiment, in which the semiconductor pattern is exposed after such a process, the resist residue is removed by the above process, so that the problem of out-of-focus caused by the rise of the resist at the boundary where the resist etc. has been removed is solved.

In the above embodiment, the optical sensor 7, the rotation mechanism 1, the drive mechanism 1
3 etc. were controlled by the control unit 14. However.

The rotation drive circuit for the mounting table is constructed as shown in one embodiment of the control block shown in FIG.

That is, the reference signal generator 20 generates a set clock. The sensor drive circuit 21 uses this clock signal to form a drive pulse. On the other hand, the drive pulse for the rotation mechanism 1 is formed by the rotation drive circuit of the mounting table based on the pulse frequency-divided by the 1 frequency divider 22. The drive pulse then controls the scanning of the optical sensor 7.

The output processing circuit 24 of the optical sensor compares the output signal level with a set threshold value for each scanning pulse of the optical sensor 7. Then, the outer peripheral end face of the semiconductor wafer 3 is detected from the position of the photodetection sense section. As a result, information on the outer peripheral end face is written into the memory element 25. When the peripheral edge of the semiconductor wafer 3 comes to the location where the light irradiator 11 is placed.

Drive circuit 26 and drive mechanism 1 according to information in memory element 25
3, the exposure light irradiation body 11 is moved,
Control is performed so that the peripheral edge of the semiconductor wafer 3 is exposed.

Furthermore, the movable mechanism 12 of the above embodiment has been explained using a ball screw. However, it is sufficient if the light irradiator 11 can be moved to a desired position. Therefore, a mechanism using a timing belt or a near motor may be used. Furthermore, in order to improve the cleanliness of the apparatus, the movable mechanism 12 may be set below the semiconductor wafer 3 as shown in FIG.

In the above embodiment, the optical sensor 7 is a solid-state image sensor C.
The explanation was made using a CD image sensor. However, any device may be used as long as it can detect the peripheral edge of the semiconductor wafer 3 without contact, and is not limited to the above embodiment.

Further, the exposure process to be applied to the object to be processed may be performed multiple times to a specific peripheral portion of the object to be processed.

Further, it is preferable that the amount of light for the exposure process applied to a specific peripheral edge of the object to be processed is set to be larger than the amount of light applied to peripheral areas other than the specific peripheral edge.

Further, the length of the exposure area is appropriately set to a predetermined distance from the outer peripheral end face of the object to be processed toward the center of the object to be processed. Detection of the outer circumferential end face of the object to be processed can be performed optically, for example, using an optical sensor consisting of a solid-state image sensor. Further, it is preferable that the width of the exposure area is appropriately determined by selectively slowing down the rotation speed of the object to be processed.

The movable mechanism also detects the outer peripheral end surface of the object to be processed.
It is desirable that the device be configured to operate in response to a signal from an end face detection means.

Further, as the end face detection means, it is desirable to use one equipped with an optical sensor consisting of, for example, a solid-state image carrier.

Furthermore, in the above embodiment, the treatment of the surface of the semiconductor wafer 3 was explained. However, it is only necessary to treat the peripheral edge, and it goes without saying that the back surface can also be treated in the same way.

In the above embodiment, the semiconductor wafer 3 was used as the object to be processed. However, any object to be processed may be used as long as it is coated with a film, and a rectangular glass substrate such as a liquid crystal display device may be processed.

In the above embodiment, the peripheral edge of the semiconductor wafer 3 was exposed with the rotating shaft fixed. However, the rotation axis position may be adjusted based on information about the outer peripheral end surface of the semiconductor wafer 3. In short, any means for adjusting the relative positions of the semiconductor wafer 3 and the light irradiator 11 may be used.

As described above, according to this embodiment, the semiconductor wafer 3
is placed on the mounting table 2. Then, while rotating the semiconductor wafer 3, the control unit 14 detects the outer peripheral end face of the semiconductor wafer 3 with the optical sensor 7 and calculates a desired exposed portion. Then, exposure is performed while controlling the position of the light source for exposure to move relative to the semiconductor wafer 3. As a result, only a desired portion of the resist or the like on the semiconductor wafer 3, including the orientation flat portion, can be removed. Moreover, it is possible to eliminate the swelling at the border of the removal of the resist, etc., and to prevent the occurrence of out-of-focus.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing the configuration of an example of an exposure apparatus for carrying out the exposure method of the present invention, FIG. 2 is an explanatory diagram showing the main parts of the apparatus shown in FIG. 1 is a block diagram showing how to control the drive of the device shown in FIG. 1, FIG. 4 is an explanatory diagram of another embodiment of the light source movable mechanism of the device shown in FIG.
FIG. 3 is a flow diagram for explaining the operation of the device shown in the figure. DESCRIPTION OF SYMBOLS 1... Rotating mechanism, 2... Mounting table, 3... Semiconductor wafer, 8... End face detection means, 11... Light irradiation body, 12... Movable mechanism, 14... Control unit .

Claims (2)

[Claims] (1) A step of detecting the outer peripheral edge of the object to be processed, a step of determining a predetermined exposure area on the periphery of the object to be processed from the outer edge detected in this step, and a step of irradiating the exposure area with light. An exposure method comprising: (2) A mounting table on which the object to be processed is placed, a rotation mechanism that rotates the mounting table at a predetermined rotation speed, a light irradiator provided opposite to the mounting surface of the mounting table, and a light amount control means for controlling the amount of light irradiated from the light irradiator to the object to be processed;
a movable mechanism that reciprocates the light irradiator along a virtual straight line passing through the center of the mounting surface; and a rotation speed control that controls the rotation speed of the mounting base according to the amount of light irradiated from the light irradiator. An exposure apparatus comprising means.