JP2888339B1 - Workpiece holding plate - Google Patents

Abstract

An object of the present invention is to provide a wafer holding plate on which a detection by a sensor can be surely performed and a marking which does not adversely affect a product is given. SOLUTION: A circular template 2 or a circular plate 1 attached to a circular plate 1 made of a hard and brittle material.
The marking M is sandwiched between the hard and brittle plate 1 and the template 2 by making the circular template 2 a transparent or translucent resin template so that it can be detected by an optical sensor. Without being exposed on the polished surface side surface, it can be clearly detected by the optical sensor.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a workpiece holding plate (hereinafter referred to as a wafer holding plate) for holding and polishing a thin workpiece such as a silicon semiconductor wafer. More specifically, the present invention relates to a wafer holding plate in which one side of a resin template having a transmittance equal to or higher than a predetermined value is marked so as to be detectable by an optical sensor and the surface is attached to a plate made of a hard and brittle material.

[0002]

2. Description of the Related Art Conventionally, in the wax-free polishing, an object to be polished can be polished without using a wax.
The wax washing step can be omitted, and the use of substances that are harmful to the natural environment such as organic solvents required for the washing can be avoided. For this reason, it is a polishing method that is increasing in recent years. Usually, in wax-free polishing of a silicon semiconductor wafer or the like, a wafer holding plate is used to hold a wafer during polishing. In this wafer holding plate, a resin circular template having a plurality of or a single circular hole opened is attached to a circular hard and brittle material plate, and water is further applied to a wafer suction pad attached to the bottom of the opening of the circular hole. After holding the wafer by pressing and adsorbing the wafer to the bottom of the opening of the circular hole, the wafer holding plate is mounted on the polishing apparatus, and the polishing slurry is supplied and rubbed between the polishing surface and the polishing cloth. Exercise and polish. After the completion of the polishing, the wafer holding plate is taken out of the polishing apparatus, the wafer is separated from the plate by the spray water, and stored in a wafer storage cassette. However, as the size of the wafer holding plate increases, the physical burden on the operator is reduced. The following methods have been implemented due to automation and safety. The wafer holding plate recovered from the polishing apparatus is sucked and conveyed by a robot arm or the like, and is mounted on a rotatable turntable directly connected to a driving unit. Above the turntable, a reflection-type optical sensor is installed, which detects the marking on the outer surface of the template on the polished surface side, rotates the wafer in a predetermined manner, and sequentially ejects a wafer to be peeled by an ejection nozzle and a wafer. It is accurately located on the straight line connecting the storage cassettes. Thereafter, the jet water from the jet nozzle is jetted toward the gap between the wafer and the circular hole to separate the wafer, and is stored in a wafer storage cassette via a shooter.

[0003]

However, in the conventional method of controlling the position of the wafer by detecting the marking on the outer surface on the polished surface side of the outer peripheral portion of the template by the reflection type optical sensor as described above, The following problems occurred. The marking applied to the outer peripheral portion of the wafer holding plate is a simple geometric shape such as a rectangle or a circle having a certain area drawn or stamped on the template surface on the wafer polishing surface side, and the template surface has a certain size or more. It has a difference in brightness. When the marking portion is detected by the sensor, the turntable on which the holding plate is placed is stopped at a predetermined position, and the wafer to be peeled can be accurately positioned. However, since the marking is drawn or engraved on the template surface on the wafer polished surface side, if the marking is drawn, it is rubbed by a polishing cloth every time the wafer is polished, and the marking gradually disappears, and the detection by the sensor It loses its function. If the difference in brightness from the template surface disappears even if it does not completely disappear, there is a possibility that the turntable drive system malfunctions. In addition, the marking itself may be eluted into the slurry during polishing, causing a problem of contamination.

In view of the problems described above, it is an object of the present invention to provide a wafer holding plate which is reliably detected by a sensor, reliably performs the wafer positioning function of the present invention, and is marked so as not to adversely affect products. .

[0005]

In order to achieve the above-mentioned object, according to the first aspect of the present invention, there is provided a method for holding a thin plate-shaped workpiece and polishing the workpiece. In a workpiece holding plate in which a resin-made circular template having a plurality of or a single circular hole opened on a circular plate made of a hard and brittle material, a marking is provided on the joining surface side of the circular template or the circular plate. The circular template is a transparent or translucent resin template so that the reflected light from the optical sensor can be reliably detected. According to a second aspect of the present invention, in addition to the configuration of the first aspect of the present invention, a configuration is provided in which the thickness of the resin template is 0.5 mm or more and 1.8 mm or less, and the visible light transmittance is 20% or more. In addition, the difference in brightness between the marking portion and the surrounding area is reliably detected by the reflected light from the optical sensor. According to a third aspect of the present invention, in addition to the configuration of the first or second aspect of the present invention, a configuration is provided in which the optical sensor targets visible light, laser, or infrared light and has a wavelength in a range of 300 nm to 0.5 mm. It is characterized by the following.

[0006]

According to the first aspect of the present invention, there is provided a circular template attached to a circular plate made of a hard and brittle material or a marking on a joint surface side of the circular plate so that the circular template can be detected by an optical sensor. By using a transparent or translucent resin template,
The marking part is not sandwiched between the hard and brittle plate and the template, and is not exposed on the polished surface side, it can be reliably detected by the optical sensor, and the marking part during polishing like when drawing on the template surface as in the past Elutes into the slurry and there is no adverse effect on the product due to contamination. According to a second aspect of the present invention, with respect to the configuration of the first aspect,
The thickness of the resin template is 0.5 mm or more and 1.8 mm
In the following, a configuration in which the visible light transmittance is set to 20% or more is added, so that the light attenuation is small, and there is an effect that the difference in brightness between the marking portion and the surroundings is reliably detected by the reflected light from the optical sensor. According to a third aspect of the present invention, in the configuration according to the first or second aspect, the optical sensor targets a visible light, a laser, or an infrared ray, and its wavelength is from 300 nm to 0.1.
A configuration with a range of 5 mm has been added so that markings of normal size can be reliably detected and can be operated properly regardless of the material and surface roughness of the template and hard and brittle plate. Becomes

[0007]

Embodiments of the present invention will be described below with reference to the drawings. 1 and 2 are a sectional view and a plan view of a wafer holding plate P according to the present invention. (However,
For the sake of explanation, this drawing is shown upside down from the state at the time of polishing.) The holding plate P is a circular base plate 1 (20 mm thick) made of a hard and brittle material such as glass, and has an inner diameter of 1 mm.
A circular template 2 having six 51 mm circular holes (holes) 2a is bonded. This circular template 2
0.5mm thick by resin with visible light transmittance of 20% or more
From 1.8mm. In the case of the present embodiment, the thickness of the epoxy resin is about 1.50% with an epoxy resin having a visible light transmittance of about 50%.
It is formed to 5 mm. The circular hole 2a has a wafer suction pad 3 (having a thickness of 1 m) having a diameter smaller by 1 to 2 mm than its inner diameter.
m) is glued.

Further, a black marking M having a width of 3 mm and a length of 5 mm is provided on an outer peripheral portion of the template 2 or the circular base plate 1 on the wafer holding surface side.
The marking M is such that the sensor detects the portion on which the marking M is applied by a change in reflected light between the portion on which the marking M is applied and the other portion. In the case of the embodiment, before the template 2 is bonded to the base plate 1, the image is drawn on the bonding surface side of the template 2.

[0009] Visible light (red light having a wavelength of about 700 nm) emitted from a light-emitting portion of an optical sensor (not shown) transmits through the template 2 (partly reflected on the surface of the template 2), and is exposed to light. The light reaches the boundary surface of the source plate 1 and is reflected. This reflected light passes through substantially the same path of the template 2 and enters the light receiving portion of the optical sensor. At this time, since the circular template 2 has a thickness of 1.5 mm and a visible light transmittance of 50%, the optical sensor can reliably detect a change in reflected light.

[0010]

As described above, according to the first aspect of the present invention, the marking is performed on the joining surface side of the circular template or the circular plate attached to the circular plate made of hard and brittle material, By using a transparent or translucent resin template for the circular template so that it can be detected by the optical sensor, the marking part is sandwiched between the hard and brittle plate and the template and is not exposed on the polished surface side. Since the detection can be reliably performed, it is possible to provide a wafer holding plate on which marking that does not adversely affect the product is performed while the wafer positioning function is reliably performed. Therefore, unlike the conventional one in which the marking is drawn on the template surface, the marking portion does not disappear by being rubbed by the cloth during polishing, and the marking portion during polishing as in the conventional case where the marking is drawn on the template surface Is eluted in the slurry, and there is no adverse effect on the product due to contamination, and it can be used for a long period and is economical.

According to a second aspect of the present invention, in addition to the effects of the first aspect, the thickness of the resin template is set to 0.5 mm or more and 1.8 mm or less, and the visible light transmittance is set to 20% or more. Since the light attenuation is small, the difference in brightness between the marking portion and the surrounding area can be reliably detected by the reflected light from the optical sensor, and the positioning of the holding plate can be performed without any trouble.

According to a third aspect of the present invention, in addition to the effects of the first or second aspect, the optical sensor targets a visible light, a laser, or an infrared ray, and its wavelength is from 300 nm to 0.2.
5mm range, so that it can support marking of a wide range of sizes and shapes regardless of the material and surface roughness of the template and hard and brittle plate, and select an inexpensive and suitable sensor.
It can be operated reliably.

[Brief description of the drawings]

FIG. 1 is a sectional view of a wafer holding plate showing one embodiment of the present invention.

FIG. 2 is a plan view of the same.

[Explanation of symbols]

W Workpiece (wafer) M Marking 1 Plate (base plate) 2 Template 2a Circular hole

Claims (3)

(57) [Claims] 1. A plurality of or a single circular hole in a circular plate (1) made of a hard and brittle material for holding a thin plate-shaped workpiece (W) and polishing the workpiece (W). (2a)
A workpiece holding plate to which a resin-made circular template (2) having an opening is attached, wherein the circular template (2) or the circular plate (1) is provided.
3. A workpiece holding plate, characterized in that a marking (M) is provided on the joining surface side of (1) and the circular template (2) is a transparent or translucent resin template so that it can be detected by an optical sensor. 2. The method according to claim 1, wherein the thickness of the resin template is set to a value of 0.1.
2. The workpiece holding plate according to claim 1, wherein the visible light transmittance is 5 mm or more and 1.8 mm or less, and the visible light transmittance is 20% or more. 3. The optical sensor is intended for visible light, laser or infrared light, and has a wavelength of from 300 nm to 0.2.
3. The workpiece holding plate according to claim 1, wherein the plate has a range of 5 mm.