JP2001300847A - Polishing device and method of manufacturing semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polishing device for preventing a polishing liquid from scattering to an optical measuring means (an end point detector) at polishing time and accurately detecting a polishing end point or measuring the film thickness. SOLUTION: This polishing device is provided with the optical measuring means being arranged above a workpiece and measuring the reflected light from the workpiece by irradiating the measuring light to the workpiece and a polishing liquid sticking preventive means arranged in the vicinity of the optical measuring means so as to prevent sticking of the polishing liquid to the optical measuring means. The measuring light is passed and/or transmitted through at least a part of the polishing liquid sticking preventive means.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polishing apparatus suitable for flattening and polishing a semiconductor device in a method of manufacturing a semiconductor device such as an ULSI, and a method of manufacturing a semiconductor device using the same. .

[0002]

2. Description of the Related Art As the degree of integration and miniaturization of a semiconductor integrated circuit increases, the steps of a semiconductor manufacturing process are increasing and becoming more complicated. Along with this, the surface of the semiconductor device is not necessarily flat. The presence of a step on the surface of a semiconductor device causes disconnection of wiring, an increase in local resistance, and the like, resulting in disconnection and a decrease in electric capacity.
In addition, in the case of an insulating film, withstand voltage degradation and leakage may occur.

On the other hand, as semiconductor integrated circuits become more highly integrated and miniaturized, the light source wavelength of a semiconductor exposure apparatus used for optical lithography becomes shorter, and the numerical aperture of a projection lens of the semiconductor exposure apparatus, the so-called NA, becomes larger. It has become to. As a result, the depth of focus of the projection lens of the semiconductor exposure apparatus has been substantially reduced. In order to cope with a shallower depth of focus, the surface of a semiconductor device needs to be flatter than ever.

As a method of flattening the surface of such a semiconductor device, a chemical mechanical polishing (Chemical Mechani
cal Polishing or Chemical Mechanical Planarizatio
n, hereinafter referred to as CMP). C
MP is a process of removing the surface irregularities of a wafer by using a chemical action (dissolution with a polishing liquid or a solution) in combination with physical polishing, and is the most promising candidate for global planarization technology.

FIG. 5 is a schematic configuration diagram of a polishing apparatus used in a conventional CMP. Polishing device is polishing plate 3, polishing plate 3
A polishing body 4, an object-to-be-polished holding section (hereinafter, referred to as a holder) 1, and a polishing liquid supply section 5 are attached to the polishing body 4. The wafer 2 to be polished is attached to the holder 1, and the polishing liquid supply unit 5 supplies the polishing liquid 6.

As the polishing body 4, a sheet-like polishing pad made of foamed polyurethane or a non-foaming resin polishing pad having a groove structure on its surface is used. The holder 1 is rotated about the axis A in the direction of arrow 100 by appropriate means, and the polishing plate 3 is rotated about the axis B in the direction of arrow 101 by appropriate means. Further, the axis B swings linearly approaching or moving away from the axis A as indicated by an arrow 102. In these processes, the polishing surface of the wafer 2 (the surface of the wafer in contact with the polishing body) is polished by the action of the polishing liquid 6 and the polishing body 4 on the wafer 2.

In the above-mentioned polishing process, a method for judging whether the polished surface of the wafer has been polished by a predetermined amount and sufficiently flattened, that is, a method of detecting the polishing end point or measuring the film thickness of the wafer, includes light reflectance and the like. Is used. An end point detector 20 which is an optical measuring means is installed on the upper part of the wafer 2.

The light source 21 is a light source for emitting light of a single wavelength such as a laser. The measurement light emitted from the light source 21 passes through a beam splitter (hereinafter referred to as BS) 22 and is incident on the polished surface of the wafer 2 protruding from the polished body 4 almost perpendicularly. The light reflected on the polished surface of the wafer 2
Then, a part of the reflected light is reflected and enters the detector 23. The reflected light is photoelectrically converted by the detector 23, and the intensity of an electric signal corresponding to the reflected light is measured.

In consideration of the embedding process of the metal electrode layer by CMP, since the extra metal layer after lamination is removed by polishing, the intensity of the electric signal corresponding to the reflected light from the metal layer surface decreases. . When the extra metal layer is removed, the area of the metal electrode layer does not change, so that the intensity of the reflected light does not change. By monitoring the intensity of the electric signal corresponding to such reflected light, it is possible to detect the polishing end point of the wafer.

[0010]

However, in the conventional polishing apparatus, the influence of the scattering of the polishing liquid on the end point detector has not been considered. Since the end point detector is installed near the wafer, the polishing liquid dropped on the polishing surface of the wafer is scattered by the rotation of the holder or the polishing body, and adheres to the optical element of the end point detector.

[0011] Then, the polishing liquid fixed to the optical element of the end point detector causes a loss of the light amount of the light reaching the detector, causing a variation in the intensity of the reflected light and a decrease in the S / N of the electric signal. As a result, it is difficult to accurately detect the polishing end point or measure the film thickness, and there is a problem that a stable polishing process cannot be performed.

Usually, an antireflection film or the like is provided on the surface of these optical elements, but this film is corroded by an acid or alkali in the polishing liquid, and causes a loss of light quantity. As a result, it is difficult to accurately detect the polishing end point or measure the film thickness, and there is a problem that a stable polishing process cannot be performed.

An object of the present invention is to provide a polishing apparatus capable of reducing the influence of the scattering of the polishing liquid and detecting the polishing end point or measuring the film thickness with higher accuracy.

Further, the present invention aims to reduce the cost of the polishing process and to improve the process efficiency by detecting the polishing end point or measuring the film thickness with higher accuracy, thereby improving the conventional semiconductor device manufacturing method. It is an object of the present invention to provide a semiconductor device manufacturing method capable of manufacturing a semiconductor device at a lower cost.

[0015]

In order to solve the above-mentioned problems, the present invention first provides a method for manufacturing a semiconductor device, comprising the steps of: "a polishing body and a polishing object are interposed between the polishing body and the polishing object; In the polishing apparatus for polishing the object to be polished by relatively moving the object, the polishing apparatus is disposed above the object to be polished, irradiates the object to be polished with measurement light, and emits light from the object to be polished. An optical measuring means for measuring the reflected light; and a polishing liquid adhesion preventing means provided near the optical measuring means so as to prevent the polishing liquid from adhering to the optical measuring means. Provides a polishing apparatus (Claim 1) characterized by passing and / or transmitting at least a part of the polishing liquid adhesion preventing means.

Second, the polishing liquid adhesion preventing means covers at least a part of the optical measuring means, and has a cover formed with an opening at a portion through which the measuring light and the reflected light pass. A polishing apparatus (Claim 2) according to claim 1, wherein the polishing apparatus is a hollow member that is connected and through which the measurement light and the reflected light pass.

Third, the polishing liquid adhesion preventing means is a cover which covers at least a part of the optical measuring means and has a transparent plate provided at a portion where the measuring light and the reflected light are transmitted. A polishing apparatus according to claim 1 (claim 3) "is provided.

Fourth, the polishing liquid adhesion preventing means further comprises a hollow member connected to the cover and through which the measuring light and the reflected light pass.
The polishing apparatus according to claim 4 is provided.

Fifth, the polishing apparatus according to claim 2 or 4, wherein the polishing liquid adhesion preventing means further comprises a gas supply device for blowing gas into a hollow portion of the hollow member. 5) ”.

Sixth, the optical measuring means irradiates the object to be polished with at least one wavelength of light to measure the reflected light, and detects the polishing end point or the amount of polishing based on a change in the reflected light during polishing. The polishing apparatus according to any one of claims 1 to 5, characterized in that the measurement is performed.

Seventhly, "the optical measuring means detects only the specular component of the reflected light, and does not detect the diffracted light of the primary light or higher." Polishing device (claim 7). "

Eighth, a "method of manufacturing a semiconductor device comprising a step of flattening the surface of a semiconductor wafer using the polishing apparatus according to any one of claims 1 to 7 (claim 8)". provide.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A polishing apparatus and a method for manufacturing a semiconductor device according to the present invention will be described below with reference to the drawings.

[First Embodiment] FIG. 1 is a schematic structural view of a polishing apparatus according to a first embodiment of the present invention. The polishing apparatus includes a polishing plate 3, a polishing body 4 attached to the polishing plate 3, an object-to-be-polished holding unit (hereinafter, referred to as a holder) 1, and a polishing liquid supply unit 5. The wafer 2 to be polished is attached to the holder 1, and the polishing liquid supply unit 5 supplies the polishing liquid 6.

As the polishing body 4, a sheet-like polishing pad made of foamed polyurethane or a polishing pad made of a non-foamed resin having a groove structure on its surface is used. The holder 1 is rotated about the axis A in the direction of arrow 100 by appropriate means, and the polishing plate 3 is rotated about the axis B in the direction of arrow 101 by appropriate means. Further, the axis B swings linearly approaching or moving away from the axis A as indicated by an arrow 102. In these processes, the polishing surface of the wafer 2 (the surface of the wafer in contact with the polishing body) is polished by the action of the polishing liquid 6 and the polishing body 4 on the wafer 2.

In the above-mentioned polishing process, a method of judging whether the polished surface of the wafer has been polished by a predetermined amount and sufficiently flattened, that is, a method of detecting the polishing end point or measuring the film thickness of the film on the wafer, includes light reflectance and the like. Is used. An end point detector 20 which is an optical measuring means is installed on the upper part of the wafer 2.

In the polishing apparatus according to the first embodiment, in order to reduce the scattering of the polishing liquid to the end point detector 20, the optical system of the end point detecting apparatus 20 is substantially covered by a cover 50 which is a polishing liquid adhesion preventing member. Covering. The light source 21 is a light source that emits light of a single wavelength, such as a laser. The measurement light emitted from the light source 21 is a beam splitter (hereinafter referred to as BS).
22. An opening 60 is formed in the cover 50, and the measurement light that has passed through the BS 22 passes through the opening 60. A cylinder 61 as a hollow member is connected to the cover 50. The measurement light that has passed through the opening 60 passes through the inside of the cylinder 61. The opening of the end 51 of the cylinder 61 on the wafer 2 side is narrowed to a size that does not block the measurement light. End 51
The measurement light that has passed through the opening of FIG. The light reflected by the polished surface of the wafer 2 passes through the inside of the cylinder 61 and the opening 60, and a part of the reflected light is reflected by the BS 22 and enters the detector 23. The reflected light is photoelectrically converted by the detector 23,
The intensity of the electric signal corresponding to the reflected light is measured.

Considering the process of embedding the metal electrode layer by CMP, since the extra metal layer after lamination is removed by polishing, the intensity of the electric signal corresponding to the reflected light from the metal layer surface decreases. . When the extra metal layer is removed, the area of the metal electrode layer does not change, so that the intensity of the reflected light does not change. By monitoring the intensity of the electric signal corresponding to such reflected light, it is possible to detect the polishing end point of the wafer.

Considering the polishing liquid scattered by the rotation of the holder 1 and the polishing body 4, since the cover 50 almost covers the end point detecting device 20, the scattered polishing liquid is not covered by the cover 5.
0 and does not adhere to optical elements and the like. Although only the terminal end 51 on the wafer 2 side is not covered and is open, the polishing liquid that penetrates into the cover 50 is very small because it is narrowed down to a size that does not block the optical path.
Further, since there is a distance from the terminal end 51 to the BS 22, the polishing liquid that has entered hardly adheres to the optical element. As a result, the surface of the optical element of the end point detection device 20 is kept in a clear state, and the loss of the light amount due to the adhesion of the polishing liquid does not occur. Thus, in the polishing apparatus according to the first embodiment, the change in the intensity of the electric signal corresponding to the reflected light becomes clear, the variation in detection of the polishing end point is reduced, and the polishing process can be efficiently managed. This has the effect.

The material of the cover 50 is preferably a material which is hardly corroded by acid or alkali. In the polishing apparatus according to the first embodiment, polyethylene which is not corroded by acid or alkali is used. I have. As a material other than polyethylene, it is preferable to use polypropylene or the like.

Further, although the cylinder is connected to the cover, the cover and the cylinder may be formed integrally.

[Second Embodiment] FIG. 2 is a schematic configuration diagram of a part of a polishing apparatus according to a second embodiment of the present invention. The polishing apparatus according to the second embodiment is a modification of the polishing apparatus according to the first embodiment, and a polishing plate, a polishing body, a holder, and a polishing liquid supply unit are omitted in FIG.
Also, in FIG. 2, the same or corresponding elements as those in FIG. 1 are denoted by the same reference numerals, and redundant description will be omitted.

In the polishing apparatus according to the second embodiment, instead of the cover connected to the cylinder installed in the polishing apparatus according to the first embodiment, the transparent plate 52 is partially provided as a polishing liquid adhesion preventing means. The installed cover 50 is used, and the optical system of the end point detection device 20 is almost covered with the cover 50 as a polishing liquid adhesion preventing member. Other configurations are the same as those of the polishing apparatus according to the first embodiment.

The transparent plate 52 is made of a material that transmits light from the light source 21, and is made of glass, acrylic, polyurethane,
Transparent materials such as polycarbonate, polystyrene, vinyl chloride, polyethylene terephthalate, polyester, or epoxy are used. Further, since the scattered polishing liquid adheres to the transparent plate 52, the material of the transparent plate 52 is:
It is preferable to have acid resistance or alkali resistance.

Considering the polishing liquid scattered by the rotation of the holder 1 and the rotation of the polishing body 4, the end point detecting device 2
Since 0 is completely covered, the scattered polishing liquid does not adhere to the optical element or the like of the end point detection device 20. Here, the transparent plate 52 can be replaced. If the scattered polishing liquid adheres to the transparent plate 52 due to polishing, the transparent plate 52 can be replaced with a new transparent plate to reduce the effect of the decrease in the amount of light. Generally, these transparent plates 52 are inexpensive compared to optical elements such as BS22, and do not require optical adjustment or the like, and exchange does not take much time. As described above, the surface of the optical element of the end point detection device 20 is kept in a clear state, and no loss of light amount due to the adhesion of the polishing liquid occurs. For this reason, the intensity change of the reflected light becomes clear, the variation in the determination of the polishing end point is reduced, and the polishing process can be efficiently managed.

In the polishing apparatus according to the first embodiment, the end point detector is covered with a cover to which the cylinder is connected to prevent the polishing liquid from adhering to the optical element or the like of the end point detector. In the polishing apparatus according to the second embodiment,
By covering the end point detector with a cover provided with a transparent plate, the polishing liquid is prevented from adhering to the optical element and the like of the end point detector, so that the same advantages as the polishing apparatus according to the first embodiment can be obtained. .

In the polishing apparatuses according to the first and second embodiments, the detection of the polishing end point by the end point detector 20 has been described as the detection of the polishing end point from the reflection intensity measurement in the metal layer polishing process. However, the present invention is not limited to this.
lation) and the detection of the polishing end point in the planarization process of the interlayer insulating film.

In the polishing apparatuses according to the first and second embodiments, the reflectance is not measured by a single wavelength.
The reflectance can be measured at multiple wavelengths, or the end point of polishing can be detected or the film thickness can be measured from the measurement of the spectrum of the reflected light.

[Third Embodiment] FIG. 3 is a schematic structural view of a part of a polishing apparatus according to a third embodiment of the present invention. The polishing apparatus according to the third embodiment is a modification of the polishing apparatus according to the first embodiment, and a polishing plate, a polishing body, a holder, and a polishing liquid supply unit are omitted in FIG.
Further, in FIG. 3, the same or corresponding elements as those in FIG. 1 are denoted by the same reference numerals, and the description thereof will not be repeated.

The difference between the polishing apparatus according to the third embodiment and the polishing apparatus according to the first embodiment is that the polishing apparatus according to the third embodiment is used as an optical measuring means, for example, in a process of flattening an interlayer insulating film. Endpoint detector 30 for monitoring
And that the transparent plate 56 is
That is, a hole is formed in the side wall of the cylinder 61, and a supply path 55 and a gas supply device 54 are newly added.

The measuring light emitted from the white light source 31 having a multi-wavelength component passes through the lenses 32, 33 and BS 38, is made substantially parallel by the lens 34, passes through the transparent plate 56,
The light passes through the cylinder 61 and is vertically incident on the wafer 2. As the white light source 31, a xenon lamp or a halogen lamp can be used. Specularly reflected light (zero-order light) from wafer 2
Passes through the cylinder 61, passes through the transparent plate 56, passes through the lens 34, and is partially reflected by the BS 38. BS
The light reflected by 38 is made substantially parallel by a lens 35, reflected by a mirror 40, and transmitted through lenses 36 and 37. The light transmitted through the lens 37 is diffracted by the diffraction grating 41 according to each wavelength, and is incident on the linear sensor 42.

Here, considering the reflected light from the wafer having the device pattern, there are many diffracted lights other than the specularly reflected light that cannot be ignored in terms of light quantity. The diffracted light produces n-th order diffracted light at a diffraction angle θ represented by the following equation (1) in accordance with the pitch (fine structure period) d of the device pattern and the wavelength λ of the measurement light.

Dsin θ = nλ (1) Since the diffracted light has an angle θ different from that of the specularly reflected light, it enters the lens 36 at an angle different from that of the specularly reflected light and converges to a place different from the focal point of the lens 36. Is done. Therefore, the diffracted light is blocked by the light blocking slit 39 and does not enter the linear sensor 42.

The linear sensor 42 measures the reflected light intensity corresponding to each wavelength of the incident regular reflected light, and inputs it to the arithmetic unit 43. Now the SiO ₂ formed on the wafer ₂
Will be considered. The reflectance of white light reflected by the interlayer insulating film has a dispersion characteristic according to the film thickness. Based on the dispersion intensity information of the white light source 31 measured in advance,
The arithmetic unit 43 calculates the thickness of the interlayer insulating film on the wafer 2 from the dispersion characteristic of the reflectance. Since the diffracted light is removed from the reflected light intensity, it is not necessary to consider the influence of the pitch of the device pattern, so that the calculation of the film thickness is simplified.

In the cover 50 of the polishing apparatus according to the third embodiment, the transparent plate 56 is attached to the end point detecting device 30 side, and the terminal 53 on the wafer 2 side is the same as in the polishing apparatus according to the first embodiment. It is narrowed down to a size that does not block the measurement optical path. In the third embodiment, a gas supply device 54 is newly added, and the gas supply device 54 blows air through a supply path 55 to a hollow portion in the cylinder 61. Since the end point detection device 30 is closed by the transparent plate 56, the sent air is constantly blown out only from the terminal end 53.

Considering the polishing liquid scattered by the rotation of the holder 1 and the polishing body 4, since the cover 50 completely covers the end point detection device 30, the scattered polishing liquid is not covered by the cover 5.
0 and does not adhere to optical elements and the like. Wafer 2
Although the terminal 53 on the side is not covered and is open, the polishing liquid does not enter the cylinder because air is always blown out from the terminal 53. Although the transparent plate 56 is provided on the end point detecting device 30 side, the scattered polishing liquid does not adhere to the transparent plate 56. As a result, the surface of the optical element of the end point detection device 30 is kept in a clear state, and the loss of the light amount due to the adhesion of the polishing liquid does not occur.

In the polishing apparatus according to the first embodiment, the end point detector is covered with a cover to which the cylinder is connected to prevent the polishing liquid from adhering to the optical element or the like of the end point detector. Similarly, in the polishing apparatus according to the third embodiment, the end point detector is covered with a cover to which the cylinder is connected, thereby preventing the polishing liquid from adhering to the optical element or the like of the end point detector. The same advantages as the polishing apparatus according to the embodiment can be obtained. Further, in the polishing apparatus according to the third embodiment, a transparent plate and a gas supply device are provided to blow off the polishing liquid scattered in the cylinder. For this reason, the change in the intensity of the reflected light becomes clear, the variation in detection of the polishing end point and the measurement error of the film thickness are further reduced, and there is an effect that the polishing process can be efficiently managed.

Although the gas supply device sends out air, a gas other than air may be sent out.

The transparent plate may not be provided in the polishing apparatus according to the third embodiment.

In the polishing apparatuses according to the second and third embodiments, nothing is particularly applied to the surface of the transparent plate, but a water-repellent coating is applied to the surface on which the polishing liquid scatters. This can further enhance the effect of removing the polishing liquid. As the water-repellent coating, a fluorine coating or the like is used.

In the polishing apparatuses according to the second and third embodiments, the transparent plate is installed almost perpendicular to the measuring light, but the transparent plate is installed obliquely to the measuring light. good. Such an oblique installation is preferable because the polishing liquid attached to the transparent plate flows down from the portion through which the measurement light passes. Further, it is preferable that the light reflected by the transparent plate out of the measurement light does not enter the detector.

In the polishing apparatuses according to the first and second embodiments, the end point detector 30 used in the polishing apparatus according to the third embodiment may be used instead of the end point detector 20. In the polishing apparatus according to the third embodiment, the end point detector 20 used in the polishing apparatus according to the first embodiment may be used instead of the end point detector 30.

In the polishing apparatus according to the first, second, and third embodiments, the cover is provided so as to cover the entire end point detector, but the polishing liquid in the cover does not scatter. The cover may be omitted from the portion, and the end point detector may be exposed.

In the polishing apparatuses according to the first, second, and third embodiments, the polishing liquid is supplied directly from the polishing liquid supply section onto the wafer. May be provided, and a polishing liquid may be supplied through a polishing body.

In the polishing apparatus according to the first, second and third embodiments, a hollow member is used as a hollow member. The hollow member has a cylindrical shape having a curved cross section or a polygonal shape. It may be.

[Fourth Embodiment] FIG. 4 is a flowchart showing a semiconductor device manufacturing process. Starting the semiconductor device manufacturing process, first, in step S
At 200, an appropriate processing step is selected from the following steps S201 to S204. According to the selection, the process proceeds to any of steps S201 to S204.

Step S201 is an oxidation step for oxidizing the surface of the wafer. Step S202 is a CVD step of forming an insulating film on the wafer surface by CVD or the like. Step S203 is an electrode forming step of forming electrodes on the wafer by steps such as vapor deposition. Step S204 is an ion implantation step of implanting ions into the wafer.

After the CVD step or the electrode forming step,
Proceed to step S205. Step S205 is a CMP process. In the CMP process, the polishing apparatus according to the present invention performs flattening of an interlayer insulating film, formation of a damascene by polishing a metal film on the surface of a semiconductor device, and the like.

After the CMP step or the oxidation step, the process proceeds to step S206. Step S206 is a photolithography step. In the photolithography process, a resist is applied to the wafer, a circuit pattern is printed on the wafer by exposure using an exposure device, and the exposed wafer is developed. Further, the next step S207 is an etching step of removing portions other than the developed resist image by etching, removing the resist, and removing unnecessary resist after etching.

Next, it is determined in step S208 whether all necessary processes have been completed, and if not, step S20
Returning to 0, the previous steps are repeated to form a circuit pattern on the wafer. If it is determined in step S208 that all steps have been completed, the process ends.

In the method of manufacturing a semiconductor device according to the present invention, since the polishing apparatus according to the present invention is used in the CMP step, the accuracy of detecting the polishing end point or measuring the thickness of the film in the CMP step is improved. Yield is improved. As a result, there is an effect that a semiconductor device can be manufactured at a lower cost than a conventional semiconductor device manufacturing method.

The polishing apparatus according to the present invention may be used in a CMP step of a semiconductor device manufacturing process other than the semiconductor device manufacturing process described above.

[0063]

As described above, according to the present invention,
Since the polishing liquid does not adhere to the end point detector, a polishing apparatus capable of detecting the polishing end point or measuring the film thickness with higher accuracy can be provided.

Further, according to the present invention, the cost of the polishing process is reduced, and the process efficiency is improved by detecting the polishing end point or measuring the film thickness with higher accuracy.
Thus, a semiconductor device manufacturing method capable of manufacturing a semiconductor device at a lower cost than a conventional semiconductor device manufacturing method can be provided.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a polishing apparatus according to a first embodiment of the present invention.

FIG. 2 is a schematic configuration diagram of a part of a polishing apparatus according to a second embodiment of the present invention.

FIG. 3 is a schematic configuration diagram of a part of a polishing apparatus according to a third embodiment of the present invention.

FIG. 4 is a flowchart showing a semiconductor device manufacturing process.

FIG. 5 is a schematic configuration diagram of a polishing apparatus used for conventional CMP.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Polishing object holding part (holder) 2 ... Wafer 3 ... Polishing plate 4 ... Polishing body 5 ... Polishing liquid supply part 6 ... Polishing liquid 20, 30 ... End point detector 21, 31 ... Light source 22, 38 ... Beam splitter ( BS) 23 Detector 32, 33, 34, 35, 36, 37 Lens 39 Shield slit 40 Mirror 41 Diffraction grating 42 Linear sensor 43 Calculator 50 Cover 51, 53 Terminal 52, 56 Transparent plate 54 ... Gas supply device 55 ... Supply path 61 ... Cylinder

Claims (8)

[Claims] 1. A polishing apparatus for polishing an object to be polished by relatively moving the object to be polished and the object to be polished while a polishing liquid is interposed between the object to be polished and the object to be polished. An optical measuring unit that is arranged above the polishing target and irradiates a measuring light to the polishing target to measure reflected light from the polishing target; and the polishing liquid to the optical measuring unit. And a polishing liquid adhesion preventing means provided near the optical measuring means so as to prevent adhesion of the polishing liquid, wherein the measurement light passes and / or transmits through at least a part of the polishing liquid adhesion preventing means. A polishing apparatus characterized by the above-mentioned. 2. A cover, wherein the polishing liquid adhesion preventing means covers at least a part of the optical measuring means, and has an opening formed in a portion through which the measuring light and the reflected light pass,
The polishing apparatus according to claim 1, further comprising a hollow member connected to the cover and through which the measurement light and the reflected light pass. 3. The polishing liquid adhesion preventing means is a cover which covers at least a part of the optical measuring means, and a transparent plate is provided at a portion through which the measuring light and the reflected light are transmitted. The polishing apparatus according to claim 1, wherein 4. The polishing apparatus according to claim 3, wherein said polishing liquid adhesion preventing means further includes a hollow member connected to said cover and through which said measuring light and said reflected light pass. 5. The polishing apparatus according to claim 2, wherein said polishing liquid adhesion preventing means further includes a gas supply device for blowing gas into a hollow portion of said hollow member. 6. The optical measuring means irradiates the object to be polished with light having at least one wavelength or more and measures the reflected light, and detects the polishing end point or measures the polishing amount based on a change in the reflected light during polishing. The polishing apparatus according to claim 1, wherein the polishing is performed. 7. The polishing apparatus according to claim 1, wherein the optical measuring means detects only a specular component of the reflected light and does not detect a diffracted light equal to or more than a primary light. apparatus. 8. A method for manufacturing a semiconductor device, comprising a step of flattening a surface of a semiconductor wafer using the polishing apparatus according to claim 1.