JPH11283944A - Method and device for polishing surface of semiconductor substrate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To set film thickness to be machined to desired film thickness by applying light onto the surface of a film via a measurement window which is provided in a polishing stand, and by using reflection interference light from a place, being used as an element in the optical measurement of the film thickness of a semiconductor substrate. SOLUTION: At a part where emission light from a film thickness measuring instrument of a polishing stand and reflection interference light from the surface of a film 5 of a semiconductor substrate 3 pass, a measurement window 2 made of quartz glass that has the quality of a material with a light transmission property and has hardness being higher than that of an abrasive 9 is used, the size of the measurement window is nearly the same as the semiconductor substrate 3, and the position of the measurement window is allowed to coincide with a position where the semiconductor substrate 3 is pressed for polishing. In this state, a signal is sent to an XYZ-stage 13 from a control part 15, the position of a film thickness measuring instrument 11 is moved, the application of light to the target position is confirmed by a pattern-recognizing device 12, and the film thickness is measured by the film thickness measuring instrument 11.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a process for polishing an oxide film formed on the surface of a semiconductor substrate, in the process of polishing, a part of the semiconductor substrate which is actually used as an element such as an IC chip during the polishing process. The present invention relates to a method and an apparatus for measuring a film thickness at a predetermined position.

[0002]

2. Description of the Related Art In a method and an apparatus for polishing a surface of a semiconductor substrate, a portion for transmitting light is provided on a polishing table, and a film provided on the surface of the semiconductor substrate is irradiated with light from the back side of the polishing table to reduce the film thickness. Japanese Patent Application Laid-Open No. 7-193033 discloses a method of calculating.
A gazette is known.

According to this, the shape of the light transmitting portion provided on the polishing table can be from a semiconductor substrate large to a concentric donut type with respect to the polishing table, or provided at four locations for simultaneous measurement. Are disclosed.

Further, the optical systems for measuring the film thickness are all disposed on the back side of the polishing table with respect to the film surface of the semiconductor substrate on the polishing table. Light is applied to the surface of the semiconductor film through the transmitting portion of the polishing table, and the reflected light is detected. The optical system is
A spectroscopic ellipsometer or an interferometry is used. Then, an unpatterned region on the semiconductor substrate is selected as a portion where the film thickness is measured.

[0005]

However, since an IC chip actually picked up from a semiconductor substrate is a patterned portion of the semiconductor substrate, it is originally necessary to measure the film thickness at a portion on the pattern. It is.

However, in the above-described example, the pattern is limited to the unpatterned portion 18 of the semiconductor substrate film surface in FIG. 6, and the film thickness on the pattern is not measured.

Further, since the semiconductor substrate is polished while being rotated, the position of the semiconductor substrate cannot be grasped when measuring the film thickness. Therefore, the film thickness at any desired position in the pattern cannot be measured. Absent.

That is, in the above-described example, when the portion where the film thickness is measured is not correlated with the polishing amount on the pattern, or when the polishing amount varies within the surface of the semiconductor substrate, The calculated polishing amount varies, making it difficult to obtain a uniform IC chip.

[0009]

According to the present invention, a semiconductor substrate is supported by a support, and a film formed on the surface of the supported semiconductor substrate is a polishing table provided to face the support. When polishing with a polishing material while moving relative to the, in the semiconductor substrate surface polishing method for optically measuring the thickness of the film during the polishing process, the optical measurement of the film thickness, A method for polishing a surface of a semiconductor substrate, characterized in that the surface of the film is irradiated with light through a measurement window provided in the polishing table and reflected interference light from a portion used as an element is used.

According to the present invention, the optical measurement of the film thickness is performed by recognizing a pattern provided on the surface of the film from the measurement window and measuring the film thickness based on the recognition result. And a method for polishing a surface of a semiconductor substrate.

According to the present invention, in the optical measurement of the film thickness, the shape of the semiconductor substrate is recognized from the measurement window, and the position where the film thickness is measured is specified based on the recognition result. A method for polishing a surface of a semiconductor substrate.

According to the present invention, the optical measurement of the film thickness is characterized in that the optical system for measuring the film thickness is movable so that light is applied to the portion where the film thickness is measured. And a method of polishing a surface of a semiconductor substrate.

According to the present invention, there is provided a semiconductor substrate surface polishing method, wherein the polishing is stopped when a result of the optical measurement of the film thickness reaches a predetermined value. is there.

Further, according to the present invention, a support for supporting a non-film surface side of a semiconductor substrate having a film formed on one side, and an abrasive material which is provided opposite to the support and performs relative movement with the support to perform polishing A polishing table for polishing the film through a polishing table, comprising: a measurement window using a light-transmitting material for at least a part of the polishing table; and the film emitted from the measurement window. A semiconductor substrate surface polishing apparatus, comprising: a film thickness measuring device for measuring the film thickness of the film based on reflected interference light from the substrate; and a pattern recognition device for recognizing a pattern provided at a predetermined position of the film in advance. In the device.

Further, according to the present invention, there is provided the semiconductor substrate surface polishing apparatus according to the present invention, wherein the measurement position of the film thickness measuring device is specified by a result of the pattern of the film recognized by the pattern recognition device.

Further, according to the present invention, the film thickness measuring device comprises:
The semiconductor substrate surface polishing apparatus is characterized in that an optical system is movable to irradiate light for measuring a film thickness to a specified portion of the film.

[0017]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is an explanatory view of a semiconductor substrate surface polishing apparatus (hereinafter referred to as a polishing apparatus). The polishing apparatus according to the present embodiment mainly includes a polishing table 1, a support table 4, a film thickness measuring device 11, and a pattern recognition device 12.

A portion through which light emitted from the film thickness measuring device 11 of the polishing table 1 and reflected light from the surface of the film 5 of the semiconductor substrate 3 pass is made of a light-transmitting material and has a higher hardness than the abrasive 9. A measurement window 2 made of quartz glass is used. The size of the measurement window 2 is substantially the same as the size of the semiconductor substrate 3, and the position where the measurement window 2 is provided matches the position where the semiconductor substrate 3 is pressed during polishing. The other part of the polishing table 1 is made of stainless steel as in the conventional apparatus, so that it can cope with the pressure applied from the support table 4.

The semiconductor substrate 3 is a silicon substrate, and a polished surface to be polished has a silicon oxide film formed thereon.

FIG. 2 is an explanatory view for explaining a rotating state of the polishing table 1 and the support table 4. The polishing table 1 is centered on the polishing table shaft 6, and the support table 4 is ground on the support table axis 5. Inside rotates each. The film thickness measuring device 11 uses a spectroscopic ellipsometer based on polarization analysis for measuring the film thickness on the substrate from the polarization state of the laser reflected on the substrate surface, and has a light emitting device and a light receiving device.

First, the polishing process by the above-mentioned polishing apparatus is as follows.
A semiconductor substrate 3 to be polished is placed on a support 4 of a polishing apparatus,
The polishing table 9 is inserted, the support table 4 and the polishing table 1 are rotated in the direction of the arrow in FIG. 2, and the surface to be polished of the silicon oxide film formed on the substrate by, for example, the CVD method is polished.

After the polishing is performed to a certain extent, the semiconductor substrate 3 is stopped on the measuring window 2 of the polishing table 1 to measure the film thickness. Here, since the abrasive 9 between the semiconductor substrate 3 and the measurement window 2 becomes a problem, the abrasive 9 is rinsed with pure water jetted from the cleaning nozzle 8 and then air is removed from the cleaning nozzle 8 to remove pure water. Is performed so that only air exists between the measurement window 2 and the measurement window 2. Thus, the thickness of the polished surface can be measured without removing the semiconductor substrate 3 from the support 4.

In the measurement of the film thickness, first, a portion for measuring the film thickness of the processed film is specified. This specification is performed by recognizing a pattern formed on the semiconductor substrate 3. To this end, a pattern recognition device 12 provided with a CCD force camera or the like is installed toward the measurement window 2 below the polishing table 1 in order to recognize the pattern on the substrate surface. By observing the substrate 3 from the measurement window 2 and comparing it with image information registered in the database 14 in advance, pattern recognition on the substrate is performed.

The control section 15 detects a predetermined film thickness measurement position based on information from the pattern recognition device 12.

After calculating the film thickness measuring position, a signal is sent from the control unit 15 to the XYZ stage 13 to measure the film thickness at a predetermined position, and the position of the film thickness measuring device 11 is moved. The pattern recognition device 12 confirms that the target position is irradiated with light, and the film thickness is measured by the film thickness measuring device 11. The film thickness measuring device 11 uses a spectroscopic ellipsometer by polarization analysis for measuring the film thickness from the polarization state of the laser light from the surface of the substrate 3 and has a light emitting device and a light receiving device.

FIG. 3 is a schematic diagram of a spectroscopic ellipsometer. The spectroscopic ellipsometer includes a light emitting device 31 and a light receiving device 3.
2 and a numerical processing circuit 33 for calculating the measured value. This is to irradiate the silicon oxide film 35 on the substrate 34 with laser light emitted from the light source of the measuring instrument, and to use the attenuation due to this absorption. The absorptance and thickness of the quartz glass, which is the passage of the laser beam, the absorptivity of the silicon oxide film 35, and the like are grasped in advance, and the film thickness is measured by the numerical processing circuit 33.

It is also possible to use an interference method for the film thickness measuring device 11. This method is mainly called a Michelson type, and is a method of measuring the film thickness by analyzing interference fringes caused by the film thickness due to reflection in the optical path.

Referring to FIG. 4, this principle is based on the fact that the light from the light emitter 51 having the same wavefront is bisected by the translucent plane mirror 52,
Both light beams are sent back by the reflecting plane mirror 53 and the surface of the object 55 to be measured, and interference fringes are generated on the translucent plane mirror 52. The interference fringes are observed by the light receiver 54 and quantified to measure the film thickness. It is. As with the spectroscopic ellipsometer, the absorptance and thickness of the quartz glass and the silicon oxide film 55
It is necessary to know in advance the absorption rate and the like.

A cell 22 is patterned on the surface of the semiconductor substrate 3 as shown in FIG. 5, for example. FIG. 6 shows a sectional structure of the cell 22. For example, it is assumed that a film thickness measurement area 23 exists in this pattern. Now, assuming that the target film thickness is D, the substrate surface is polished for an appropriate time, and the polishing is stopped.
Thereafter, the film thickness is measured again according to the above-described procedure, and if the film is polished to the target film thickness D, the polishing is terminated. If the thickness is larger than the target film thickness D, polishing and film thickness measurement are repeated until the film thickness becomes D.

The measurement position of the film thickness is specified as follows.
In the above example, for example, the image processing is performed by using a CCD camera to recognize the pattern if provided on the substrate, but the recognition may be performed by recognizing the shape of the semiconductor substrate 3.

That is, in this case, in order to give a pattern to the substrate surface, as shown in FIG.
Also, marks such as the flat portion 26 are provided.

That is, the relationship between the substrate shape specified by the mark and the patterning of the substrate surface is correlated. This relationship is stored in the database 14 in advance.
When the semiconductor substrate 3 is fixed to the support 4, the mark is detected by the substrate shape recognizing device 7, and a motor (not shown) for rotating the support shaft 5 detects the rotation angle of a pulse motor or the like. An apparatus 10 is provided.

The detection result of the substrate shape recognition device 7 and the result of collation with the database 14 and the rotation angle detected by the rotation angle measurement device 10 are sent to the control unit 15 and observed from below the polishing table 1. The direction and position of the pattern provided on the surface of the semiconductor substrate 3 observed through the measurement window 2 are obtained.

After the calculation of the film thickness measurement position, the control unit 15 controls the XYZ stage 1 to measure the film thickness at a predetermined position of the film 5.
A signal is sent to 3 and the position of the film thickness measuring device 11 is moved to measure the film thickness.

The type of the film thickness measuring device 11 is not particularly limited as long as it uses light, such as a reflection interference method or a spectroscopic ellipsometer. In addition, if the number is increased, a plurality of regions can be measured at one time, so that the variation of the film thickness on the substrate surface can be measured in a short time.

The form of the measurement window 2 may be modified to the extent that it does not interfere with pattern recognition and film thickness measurement.

The XYZ stage 13 may be a rotary stage as long as the film thickness measuring device 11 can be moved.

Further, the board shape recognition device 7 is particularly equipped with the support table 4.
It is not necessary to incorporate the notch 25 into the notch 25 and the flat part 26 if the position information of the notch 25 or the flat part 26 is given to the control unit 15 when fixing to the support base 4.

[0040]

As described in detail above, according to the present invention,
In the process of polishing a film on the surface of a semiconductor substrate, the thickness of an arbitrary position to be used as an IC chip is measured during the polishing process, and the thickness to be processed can be controlled to a desired thickness, so that good polishing is always achieved. A polishing method and an apparatus for obtaining a result can be provided.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing an embodiment of the outline of a semiconductor substrate surface polishing apparatus of the present invention.

FIG. 2 is an explanatory diagram illustrating a rotation state of a polishing table and a support table of the semiconductor substrate surface polishing apparatus of the present invention.

FIG. 3 is an explanatory diagram of a method for measuring the thickness of a film on a semiconductor substrate.

FIG. 4 is an explanatory view of another method for measuring the thickness of a film on a semiconductor substrate.

FIG. 5 is an explanatory diagram of a pattern formed on a substrate surface and a film thickness measurement region.

FIG. 6 is a cross-sectional view of a pattern formed on a substrate surface and a film thickness measurement region.

FIG. 7 is an explanatory diagram of a notch and a flat portion provided on a substrate and a film thickness measurement region.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Polishing table, 2 ... Measurement window, 3 ... Semiconductor substrate, 4 ... Support table, 5 ... Support table axis, 6 ... Polishing table axis, 7 ... Substrate shape recognition device, 8 ... Cleaning nozzle, 9 ... Abrasive material, Reference numeral 10: rotation angle measuring device, 11: film thickness measuring device, 12: pattern recognition device, 13: XYZ table, 14: database, 15
… Control unit

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI G01B 11/24 G01B 11/24 F 21/00 21/00 A H01L 21/66 H01L 21/66 Q

Claims (8)

[Claims] An abrasive is supported by supporting a semiconductor substrate on a support table and moving a film formed on the surface of the supported semiconductor substrate relative to a polishing table provided opposite the support table. When polishing by, in the semiconductor substrate surface polishing method of optically measuring the film thickness of the film during the polishing process, the optical measurement of the film thickness, the measurement window provided in the polishing table A semiconductor substrate surface polishing method, wherein light is irradiated to the surface of the film through the substrate, and reflection interference light from a portion used as an element is used. 2. The optical measurement of the film thickness includes recognizing a pattern provided on the surface of the film from the measurement window, and specifying a position where the film thickness is measured based on the recognition result. 2. The method for polishing a surface of a semiconductor substrate according to claim 1, wherein: 3. The optical measurement of the film thickness includes recognizing a shape of the semiconductor substrate from the measurement window, and specifying a position where the film thickness is measured based on the recognition result. Item 4. The method for polishing a surface of a semiconductor substrate according to Item 1. 4. The optical measurement of the film thickness is characterized in that an optical system for measuring the film thickness is movable so as to irradiate light at a position where the film thickness is measured. The method for polishing a surface of a semiconductor substrate according to claim 1, wherein 5. The method according to claim 1, wherein the polishing is stopped when a result of the optical measurement of the film thickness reaches a predetermined value. 6. A support for supporting a non-film surface side of a semiconductor substrate having a film formed on one surface, and a support provided opposite to the support and performing relative movement with the support to carry out the film via an abrasive. A polishing table, comprising: a polishing table for polishing a surface of the semiconductor substrate; and a measurement window using a translucent material for at least a part of the polishing table, and reflected interference light from the film emitted from the measurement window. 1. A semiconductor substrate surface polishing apparatus, comprising: a film thickness measuring device for measuring a film thickness of the film by using the method; and a pattern recognition device for recognizing a pattern provided at a predetermined position of the film in advance. 7. The semiconductor substrate surface polishing apparatus according to claim 4, wherein the measurement position of the film thickness measuring device is specified by a result of the film pattern recognized by the pattern recognition device. 8. The apparatus according to claim 4, wherein the film thickness measuring device has an optical system movable to irradiate light for measuring the film thickness to a specified portion of the film. Semiconductor substrate surface polishing equipment.