JP2582976B2 - Substrate presence / absence detection device in rotary substrate processing equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotating device having a substrate mounting plate for mounting a substrate such as a semiconductor wafer in a state where the outer peripheral edge of the substrate is restricted from moving in the horizontal direction. The present invention relates to an apparatus for detecting the presence or absence of a substrate in a substrate processing apparatus.

[0002]

2. Description of the Related Art A rotary substrate processing apparatus of the type in which a substrate is rotatably supported by a substrate mounting plate as described above is a so-called vacuum chuck, in which a rotating body having a concave portion communicating with a suction means formed on an upper end surface. Unlike a rotary substrate processing apparatus of a type that sucks and holds a substrate, the contact area with the substrate is small (in a vacuum chuck, all parts other than the concave portion on the upper end surface are in wide surface contact with the back surface of the substrate). The board can be supported in contact with only the peripheral edge of the board underside,
Since the lower surface of the substrate can be prevented from being damaged, there is an advantage that it can be used even when the rear surface treatment of the substrate is required.

[0003]

By the way, in a rotary type substrate processing apparatus using a vacuum chuck, when the substrate falls off from the vacuum chuck, the negative pressure for sucking and holding the substrate fluctuates rapidly. Presence or absence can be easily detected. However, since a rotary substrate processing apparatus of the type that supports a substrate by rotation on the substrate mounting plate as described above does not suck the substrate, it is difficult to detect the drop of the substrate from the substrate mounting plate. There is a disadvantage in that processing such as cleaning and resist coating is wasted without a substrate.

Therefore, a light source for projecting a light beam to a position above a substrate mounted on the substrate mounting plate, and a light beam reflected on the substrate surface or the mounting surface of the substrate mounting plate are received. A light receiver that outputs a light-receiving signal, determines the reflectance of the received light beam, determines whether the light beam is reflected from the substrate surface or the light beam reflected from the mounting surface of the substrate mounting plate, and determines the latter. It was conceived to be able to detect the absence of a substrate when discriminated, but there are various substrates to be processed, such as silicon substrates and gallium arsenide substrates, which have different reflectances. The reflectance of the surface of the substrate differs depending on the type of the substrate and the processing mode, such as formation of an oxide film or a water film on the substrate.

[0005] For this reason, there are cases where the reflectance of the substrate surface is larger or smaller than the reflectance of the mounting surface of the substrate mounting plate due to the difference in the type of the substrate and the processing mode. It is not possible to simply distinguish between a substrate and a substrate mounting plate, and according to the substrate to be processed,
Criteria for comparing and judging the magnitude of the reflectivity must be set, and there is a drawback that it is practically inconvenient.

There is also a difference between the reflectance from the surface of the substrate and the reflectance from the mounting surface of the substrate mounting plate, and the difference may be small or large. When the difference is small, there is a disadvantage that the detection accuracy is reduced.

For example, as disclosed in Japanese Patent Application Laid-Open No. 2-86144,
A light source for projecting a light beam and, on the other hand, a light receiving device for receiving a light beam from the light source and outputting a light receiving signal are provided. Although it is conceivable to configure to detect the presence or absence of the substrate, when supplying a surface treatment liquid such as pure water to the surface of the rotating substrate to perform the substrate processing, generally, the periphery of the rotating substrate is a cup. It is difficult to detect the presence or absence of the substrate at the time of rotation because of the light shielding by the cup for covering. Therefore, it is conceivable to provide a light source or a light receiver in the cup. However, it is actually difficult to detect the presence or absence of the substrate during rotation because the surface treatment liquid adheres to the light source or the light receiver.

The present invention has been made in view of such circumstances, and it is possible to accurately detect the presence or absence of a substrate on a substrate mounting plate during rotation, regardless of the type of substrate or the difference in processing form. The purpose is to be.

[0009]

According to the present invention, there is provided a rotary substrate processing apparatus for detecting the presence or absence of a substrate in a rotary substrate processing apparatus in which the outer peripheral edge of the substrate is restricted from moving in the horizontal direction in order to achieve the above-mentioned object. A substrate presence / absence detection device in a rotary substrate processing apparatus provided with a substrate placement plate on which a substrate is placed so as to be rotatable around a vertical axis, wherein the reflectance is relatively high on the upper surface of the substrate placement plate. Forming a substrate detecting section composed of different high-reflection areas and low-reflecting areas, a light source for projecting a light beam to the substrate detecting section and a light beam reflected by the substrate detecting section are received above the substrate mounting plate. And a light receiver that outputs a light reception signal, based on the light reception signal from the light receiver.
With the rotation of the substrate mounting plate, based on detecting the fluctuation characteristics of the reflected light corresponding to the formation pattern of the high reflection area and the low reflection area, if there is no substrate on the substrate mounting plate The controller is provided with a controller that determines the presence or absence of a substrate according to the determination procedure.

[0010]

According to the present invention, when a substrate is not present on a rotating substrate mounting plate, a light beam projected from a light source irradiates the upper surface of the substrate mounting plate, and the light beam is
At some point in the rotation, the light is reflected in a high reflection area at the substrate detecting portion on the substrate mounting plate, and at another point in time, the light is reflected in a low reflection area. For this reason, the output from the photodetector that detects the reflected light has a characteristic variation characteristic corresponding to the formation pattern of the high-reflection area and the low-reflection area in the substrate detection unit as the substrate mounting plate rotates. . On the other hand, when the substrate is mounted on the substrate mounting plate, the light receiver does not detect the reflected light from the substrate detection unit, and thus the formation of the high reflection area and the low reflection area in the substrate detection unit as described above. It does not have a characteristic variation characteristic corresponding to the pattern. Therefore, it is determined that the substrate is not present on the substrate mounting plate by detecting the characteristic fluctuation characteristic of the reflected light corresponding to the formation pattern of the high reflection area and the low reflection area with the rotation of the substrate mounting plate. The controller that operates in the following procedure detects the absence of a substrate only when there is no substrate on the substrate mounting plate. That is, even if it cannot be said that the presence of the substrate itself is directly detected, the presence or absence of the substrate is detected by reliably detecting the absence of the substrate.

[0011]

Next, an embodiment of the present invention will be described in detail with reference to the drawings.

<First Embodiment> FIG. 1 is a schematic perspective view showing an apparatus for detecting the presence or absence of a substrate in a rotary substrate processing apparatus according to a first embodiment of the present invention.

In this rotary substrate processing apparatus, a substrate mounting plate 2 is integrally connected to an upper end of a main shaft 1 rotatably provided around a vertical axis P, and an electric motor 3 is provided at a lower end side of the main shaft 1. Interlockingly connected and the substrate mounting plate 2
A support member 4 for mounting a lower peripheral edge of a lower surface of a semiconductor substrate (hereinafter, simply referred to as a substrate) W such as a silicon wafer is protruded from an outer peripheral edge of an upper surface of the upper surface at a predetermined interval in a circumferential direction. 4. A small-diameter member 5 for restricting the movement of the outer peripheral edge of the substrate W in the horizontal direction is protrudingly provided on the upper surface of each, and a schematic perspective view of a main part of FIG. As shown in FIG. 5, the substrate W placed on the substrate W in a state where the outer peripheral edge thereof is restricted from moving in the horizontal direction is rotated around the vertical axis P, and the periphery thereof is covered with a scattering prevention cup (not shown). In this state, various surface treatments such as cleaning treatment by supplying pure water from nozzles (not shown) to both front and back surfaces of the substrate W are configured.

A high reflection area 6a having a high reflectance and a low reflection area 6b having a low reflectance are provided on the upper surface of the substrate mounting plate 2 at predetermined intervals in the circumferential direction so that the reflectance differs in the rotation direction. A substrate detection unit is configured.

A light source 7 for projecting a light beam to the substrate detecting portion and a light receiving device 8 for receiving a light beam reflected by the substrate detecting portion and outputting a light receiving signal are provided above the substrate mounting plate 2. ing.

A disk 10 having a notch 9 formed only at one position in the circumferential direction is attached to a predetermined position of the main shaft 1, and a light emitter 11 for rotation speed and a light receiver 12 for rotation speed are sandwiched between the disk 10. Is provided so that a pulse signal is output from the light receiver 12 for the number of revolutions as the light beam that has passed through the notch 9 is received.

A rotary encoder 14 is provided at a predetermined position of the main shaft 1 via a gear type transmission mechanism 13 so as to detect the rotation amount of the main shaft 1.

As shown in the block diagram of FIG. 4, each of the light receiver 8, the rotation speed light receiver 12, and the rotary encoder 14 is connected to a controller 15, and the controller 15 is connected to the electric motor 3 and the operation panel 16. The alarm device 17 is connected.

The controller 15 includes a CPU 18 and an RO.
An M19, a RAM 20, and an input / output interface 21 are provided, and the CPU 18 is configured to detect a reflection state from a substrate detection unit and determine the presence or absence of the substrate W based on a light reception signal from the light receiver 8. I have. Also,
The safety mechanism is configured to automatically stop the electric motor 3 when the absence of the substrate W is detected.

Next, the operation of the CPU 18 for judging the presence / absence of a board and stopping the rotation will be described with reference to the flowchart of FIG.

First, a start signal is output to the electric motor 3 to drive it, and the substrate mounting plate 2 is rotationally driven (S1). After that, the substrate mounting plate 2 is rotated by the rotary encoder 14 by a set rotation amount (36 °). It is determined whether or not the rotation has been completed, that is, whether or not it is a sampling period (S2).
Upon detecting that the sampling period has come, a light receiving signal from the light receiver 8 is input (S3), and it is determined whether or not the level of the light receiving signal is higher than a set level.
When the level is higher than the set level, the level value is set to "1". On the other hand, when the level is lower than the set level, the level value is set to "0", and the process proceeds to step S4.

That is, as shown in the schematic plan view of the substrate mounting plate in FIG. 6A and the output waveform diagram of the light receiving signal and the level value in FIG. When the substrate W is not mounted on the upper surface of the substrate mounting plate 2, the light beams reflected from the low-reflection regions 6 b and the high-reflection regions 6 a alternately formed at every 36 ° are received by the light receiver 8. And generates a corresponding large or small voltage as a light receiving signal. On the other hand, at the sampling period of every 36 ° set by the rotary encoder 14, the voltage levels and thresholds at the central points A1, A2,..., A9, A10 of the low reflection area 6b. By comparing with the level SL, a level value of "1" or "0" is obtained. L is the light source 7
3 shows a relative trajectory on the upper surface of the substrate mounting plate 2 onto which the light beam from the light source is projected.

In step S4, it is determined whether or not the substrate mounting plate 2 has rotated one or more times. If not, the process proceeds to step S5, where it is determined whether or not the input of the level value is the first. If the level value is stored in RAM
20 and returns from step S6 to step S2.

If the input of the level value is not the first time, the process proceeds from step S5 to step S7, where the previous level value stored in the RAM 20 is compared with the current level value. Returning to S2, conversely, if not the same, a flag is set (F ← 1) and (S
8) The current level value is stored in RAM instead of the previous level value.
20 and returns from step S9 to step S2.

If it is determined in step S4 that the substrate mounting plate 2 has made one rotation, the process proceeds to step S1.
Go to 0 and check if flag is on (F = 1?)
When the flag is set, that is, when it is determined that the level of the light receiving signal is not constant during one rotation because the substrate W is not mounted on the substrate mounting plate 2, the electric motor 3 is turned off. At the same time as the stop (S11), the alarm device 17 is activated (S12), and the process proceeds to step S13 to lower the flag (F ← 0), and the RAM 20
Deletes the level value stored in. The configuration for detecting that the substrate W is not placed on the substrate placing plate 2 and stopping the electric motor 3 is a safety mechanism.

In step S10, when the flag is not set, that is, when it is determined that the level of the light receiving signal is constant for one rotation because the substrate W is mounted on the substrate mounting plate 2, The process proceeds to step S14 to determine whether the surface treatment of the substrate W has been completed. If the surface treatment of the substrate W has not been completed, the process proceeds to step S14.
When the surface treatment of the substrate W is completed, the driving of the electric motor 3 is stopped (S15), and the RAM 2
The level value stored in 0 is deleted.

As described above, when the substrate W is not mounted on the substrate mounting plate 2, the high reflection area 6a and the low reflection area 6b formed on the upper surface of the substrate mounting plate 2 and having different reflectivities. The light beam reflected from the light receiving device is alternately received by the light receiving device 8, and based on the reception of the light receiving signals having different levels, the absence of the substrate W is detected, whereby the rotation of the substrate mounting plate 2 is automatically performed. At the same time, an alarm is issued by the alarm device 17 to notify the worker. On the other hand, when the substrate W is mounted, the light beam reflected from the surface of the substrate W with little change in reflectance is changed. The presence of the substrate W can be detected based on the reception of the light received by the light receiver 8 and the reception signal whose level does not change.

<Second Embodiment> FIG. 7A is a schematic plan view of a substrate mounting plate according to a second embodiment, and FIG. 7B is an output waveform diagram of a light receiving signal and a level value. Yes,
On the upper surface of the substrate mounting plate 2, four low-reflection areas 6b and four high-reflection areas 6a are alternately formed at random widths in the circumferential direction. On the other hand, with the sampling cycle set by the rotary encoder 14,
Positions B1, B2,... Spaced at intervals of 60 ° in the circumferential direction
In each of B5 and B6, a voltage level due to reflection from the low reflection area 6b or the high reflection area 6a is compared with the threshold level SL, and a level value of "1" or "0" is obtained.

According to the second embodiment, the sampling period cannot be set to a small value, such as every 36 ° in the first embodiment, and even if the sampling start position is set arbitrarily, During one rotation of the substrate mounting plate 2, the required level value is inverted,
There is an advantage that the assembling and the setting of the sampling start position can be easily performed.

<Third Embodiment> FIG. 8A is a schematic perspective view of a substrate mounting plate according to a third embodiment, in which five seals 22 having different widths in the circumferential direction are provided on the substrate mounting plate. 2, a low-reflection area 6b having a small reflectance is formed by each of these seals 22.
The space between the adjacent seals 22, 22 is formed in the high reflection area 6a having a high reflectance.

<Fourth Embodiment> FIG. 8B is a schematic perspective view of a substrate mounting plate according to a fourth embodiment. A high reflection area 6a having a large reflectivity is provided on the upper surface of the substrate mounting plate 2. And a low-reflection region 6b having a small reflectance and a medium-reflection region 6c having an intermediate reflectance between them, so that the threshold level SL can be easily set arbitrarily.

<Fifth Embodiment> FIG. 8C is a schematic perspective view of a substrate mounting plate according to a fifth embodiment. The substrate mounting plate 2 is different in radius at an interval in the circumferential direction. Circular holes 23a, 23b, and 23c are formed.
A low reflection area 6b having no reflection is formed by 23b and 23c.

<Sixth Embodiment> FIG. 9A is a schematic plan view of a substrate mounting plate according to a sixth embodiment. Reflection areas 6b, 6b are formed.

<Seventh Embodiment> FIG. 9B is a schematic plan view of a substrate mounting plate according to a seventh embodiment, in which three circles having different radii are formed on the upper surface of the substrate mounting plate 2. .. Are formed with low reflectance.

<Eighth Embodiment> FIG. 9C is a schematic plan view of a substrate mounting plate according to an eighth embodiment. The reflectance of the upper surface of the substrate mounting plate 2 is small due to the letters of the alphabet. .. Are formed. This 8th
According to the embodiment, there is an advantage that the low reflection area 6b or the high reflection area 6a can be formed by using a company name or a product name.

<Ninth Embodiment> FIG. 9D is a schematic plan view of a substrate mounting plate according to a ninth embodiment. Two substrates having different widths in the circumferential direction are provided on the upper surface of the substrate mounting plate 2. The low-reflection regions 6b, 6b having a small reflectance are formed by the fan portions.

The light source 7 and the light receiver 8 in the embodiment described above.
And may be configured separately or integrally. The present invention is also applicable to a rotary substrate processing apparatus of a type that is not covered with a cup during the surface processing of the substrate W.

The high-reflection area and the low-reflection area having relatively different reflectivities constituting the substrate detecting section are formed, for example, by attaching a seal to the upper surface of the substrate mounting plate as in the third embodiment. In other words, it is only necessary to realize such a configuration that does not lead to the generation of particles.

[0039]

According to the apparatus for detecting the presence or absence of a substrate in a rotary substrate processing apparatus according to the present invention, a substrate is mounted on a substrate mounting plate regardless of the reflectance of the surface of the substrate to be processed. The optical receiver detects light beams having different reflectances reflected from the substrate detecting portion formed on the upper surface of the mounting plate,
In particular, the procedure of determining that there is no substrate on the substrate mounting plate based on detecting the fluctuation characteristics of the reflected light corresponding to the formation pattern of the high reflection area and the low reflection area constituting the substrate detection unit, Is determined, the presence or absence of the substrate on the substrate mounting plate can be accurately detected irrespective of the type of the substrate and the type of the surface-treated substrate.

[Brief description of the drawings]

FIG. 1 is a schematic perspective view showing a substrate presence / absence detection device in a rotary substrate processing apparatus according to a first embodiment of the present invention.

FIG. 2 is a schematic perspective view of a main part.

FIG. 3 is a side view of a main part.

FIG. 4 is a block diagram.

FIG. 5 is a flowchart illustrating an operation of a CPU.

FIG. 6A is a schematic plan view of a substrate mounting plate,
(B) is an output waveform diagram of a light receiving signal and a level value.

FIG. 7A is a schematic plan view of a substrate mounting plate according to a second embodiment, and FIG. 7B is an output waveform diagram of a light receiving signal and a level value.

8A is a schematic perspective view of a substrate mounting plate of a third embodiment, FIG. 8B is a schematic perspective view of a substrate mounting plate of a fourth embodiment, and FIG. 8C is a substrate of the fifth embodiment. It is a schematic perspective view of a mounting plate.

9A is a schematic plan view of a substrate mounting plate of a sixth embodiment, FIG. 9B is a schematic plan view of a substrate mounting plate of a seventh embodiment, and FIG. 9C is a substrate of the eighth embodiment. FIG. 14D is a schematic plan view of a mounting plate, and FIG. 14D is a schematic plan view of a substrate mounting plate of a ninth embodiment.

[Explanation of symbols]

 2 ... Substrate mounting plate 6a ... High reflection area constituting a substrate detection section 6b ... Low reflection area constituting a substrate detection section 7 ... Light source 8 ... Receiver 15 ... Controller W ... Substrate

Claims (1)

(57) [Claims] 1. A substrate presence / absence detection in a rotary substrate processing apparatus having a substrate mounting plate on which a substrate is mounted so as to be rotatable around a vertical axis in a state in which movement of an outer peripheral edge of the substrate in a horizontal direction is regulated. An apparatus, on the upper surface of the substrate mounting plate, forming a substrate detection unit composed of a high reflection area and a low reflection area having relatively different reflectances in the rotation direction, and at a location above the substrate mounting plate. ,
A light source for projecting a light beam on the substrate detecting unit; and a light receiving unit for receiving a light beam reflected by the substrate detecting unit and outputting a light receiving signal, and mounting the substrate on the basis of the light receiving signal from the light receiving unit. With the rotation of the mounting plate, based on detecting the fluctuation characteristics of the reflected light corresponding to the formation pattern of the high-reflection area and the low-reflection area, by a procedure for determining that there is no substrate on the substrate mounting plate. An apparatus for detecting the presence or absence of a substrate in a rotary substrate processing apparatus, comprising a controller for determining the presence or absence of a substrate.