JP2008284645A - Apparatus and method for polishing - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To make the thickness of a film uniform over the whole surface of a base plate by setting pad conditioning conditions in real time during polishing. <P>SOLUTION: A polishing apparatus comprises a pad conditioning means for dressing the polishing pad over the whole range from its central portion to its peripheral portion, and a conditioning controller for changing the pad conditioning conditions according to the position in the polishing pad. The polishing apparatus further comprises a data base 21 for storing a plurality of pre-set pad conditioning conditions, a base plate film thickness measuring means 18 for measuring the shape of film thickness distribution, and a pad surface detecting means 17 for detecting the condition of the surface of the polishing pad 12. Further, the polishing apparatus comprises a pad profile forming means 22 for forming the pad profile of the polishing pad 12 by selecting the optimum pad conditioning condition from the data base 21 based on the base plate film thickness distribution information formed by the base plate film thickness measuring means 18 before polishing. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a polishing apparatus and a polishing method, and more particularly to a polishing apparatus and a polishing method for automatically controlling pad conditioning in order to uniformly polish a substrate in chemical mechanical polishing (CMP). .

  In recent years, semiconductor circuits have been miniaturized as the performance of semiconductors has increased, and the depth of focus of a stepper tends to become increasingly shallow in the lithography process. At the same time, multi-layer wiring has been developed, and the unevenness of the substrate surface tends to increase.

  Under such circumstances, it is necessary to flatten the substrate surface, and the demand for uniformly polishing the substrate in the CMP process has become more severe. A substrate to be flattened in the CMP process is formed by a film forming apparatus, but the actual situation is that the film thickness distribution in each substrate differs for each apparatus, for each lot, and for each chamber. Until now, there has been no apparatus for polishing each substrate having a different film thickness distribution in the CMP process so that all the substrates have the same film thickness.

  Conventionally, as automatic control for uniformly polishing a substrate, a technique for changing pad conditioning (pad dressing) conditions in order to maintain the shape (pad profile) of a polishing pad has been disclosed (for example, Patent Documents). 1).

Further, a technique is disclosed in which a pad profile stored as a database and a film thickness after polishing are substituted into an approximate expression of the shape of a polished film thickness distribution and fed back to pad conditioning conditions (see, for example, Patent Document 2). ).
JP 2001-129754 A JP 2005-347568 A

  In Patent Document 1 and Patent Document 2, there is a problem that optimum pad conditioning is not performed with respect to non-uniform fluctuations in the film thickness surface that are different for each substrate, and the shape in the film thickness surface after polishing is polished. There was a problem that the entire surface of the substrate was polished while leaving the shape of the previous film thickness distribution.

  In addition, since the change in film thickness cannot be monitored during polishing, even if the film thickness is measured after polishing and fed back to the pad conditioning conditions, the substrate that has been polished before the feedback can be affected by automatic control. There was no problem.

  Therefore, even if the shape of the film thickness distribution varies from substrate to substrate, optimal substrate conditions are set for each substrate before polishing, and all substrate conditions are the same by setting pad condition conditions in real time during polishing. A technical problem to be solved in order to be able to form a uniform film thickness on the entire inner surface arises, and the present invention aims to solve this problem.

  The present invention has been proposed in order to achieve the above object, and the invention according to claim 1 presses the substrate held by the polishing head against the polishing pad on the rotating platen and applies the slurry to the polishing pad. A polishing apparatus that polishes the substrate by supplying pad conditioning means for sharpening over a range from the central portion to the peripheral portion of the polishing pad, depending on the position in the polishing pad, In a polishing apparatus provided with a conditioning controller for changing pad conditioning conditions, a database storing a plurality of preset pad conditioning conditions, a substrate film thickness distribution measuring means for measuring the shape of the film thickness distribution of the substrate, and a polishing pad And a pad surface detecting means for detecting the surface state of the surface. The pad profile creation means for creating the pad profile of the polishing pad by selecting the optimum pad conditioning condition from the database based on the substrate thickness distribution information created by the substrate thickness distribution measurement means before polishing the substrate A polishing apparatus characterized by comprising:

  According to this configuration, for example, a plurality of types of pad conditioning conditions such as the pad conditioning pressure at each position in the polishing pad and the time for performing the pad conditioning are set in advance and stored in the database. Then, before the substrate is polished, the shape of the film thickness distribution is measured to create the substrate film thickness distribution information, and the optimum pad conditioning conditions are selected from the database based on the substrate film thickness distribution information, and the pad profile of the polishing pad is selected. Create Pad conditioning is performed using this pad profile. During polishing of the substrate, the substrate is polished while monitoring whether the surface state of the polishing pad matches the pad profile by the pad surface detection means.

  The invention according to claim 2 is characterized in that the substrate film thickness distribution measuring means includes substrate film thickness distribution information creating means for comparing the film thickness measurement waveforms measured at a plurality of locations on the substrate to create substrate film thickness distribution information. A polishing apparatus according to claim 1 is provided.

  According to this configuration, for example, the substrate film thickness distribution measuring unit measures the film thickness of the substrate at a plurality of locations such as the central portion and the peripheral portion of the substrate, and compares the film thickness measurement waveforms to obtain the substrate film thickness distribution information. create.

  According to a third aspect of the present invention, the substrate film thickness distribution measuring means comprises an optical or electromagnetic measuring device, and the measuring device is provided on the platen. A polishing apparatus is provided.

  According to this configuration, the substrate film thickness distribution measuring means including an optical or electromagnetic measuring device is provided on the platen to measure the film thickness of the substrate, and the substrate film thickness distribution information during polishing is created in real time.

  According to a fourth aspect of the present invention, the conditioning controller determines an optimum pad conditioning condition based on the substrate film thickness distribution information and the surface condition information of the polishing pad created during the polishing of the substrate to determine the pad profile. 4. The polishing apparatus according to claim 1, further comprising means for setting a parameter.

  According to this configuration, the substrate film thickness distribution measuring means provided on the platen measures the film thickness of the substrate being polished to create the substrate film thickness distribution information in real time, and the pad surface detecting means is used for the polishing pad. Create surface condition information in real time. Based on these pieces of information, the conditioning controller determines the optimum pad conditioning condition and sets the parameter of the pad conditioning condition selected from the database, so that the optimum pad conditioning can be performed in real time.

The invention according to claim 5 is a polishing method in which a substrate held by a polishing head is pressed against a polishing pad on a rotating platen and a slurry is supplied to the polishing pad to polish the substrate. In a polishing method that includes a step of performing pad conditioning for sharpening over a range from the center portion to the peripheral portion of the pad, and the pad conditioning conditions are changed according to the position in the polishing pad,
Set multiple pad conditioning conditions in advance and store them in the database, measure the shape of the film thickness distribution before polishing the substrate, create substrate film thickness distribution information,
A pad profile of the polishing pad is created by selecting the optimum pad conditioning condition from the database based on the substrate film thickness distribution information,
Provided is a polishing method characterized by performing automatic control so as to polish a substrate by performing pad conditioning according to the pad profile.

  According to this configuration, for example, a plurality of types of pad conditioning conditions such as the pad conditioning pressure at each position in the polishing pad and the time for performing the pad conditioning are set in advance and stored in the database. Then, before the substrate is polished, the shape of the film thickness distribution is measured to create the substrate film thickness distribution information, and the optimum pad conditioning conditions are selected from the database based on the substrate film thickness distribution information, and the pad profile of the polishing pad is selected. Create Pad conditioning is performed using this pad profile.

  A sixth aspect of the present invention is the polishing according to the fifth aspect, wherein the substrate film thickness distribution information includes a step of comparing the film thickness waveforms measured at a plurality of locations on the substrate. Provide a method.

  According to this configuration, for example, the substrate film thickness distribution measuring unit measures the film thickness of the substrate at a plurality of locations such as one end, the center, and the other end of the substrate, and compares these film thickness measurement waveforms with the substrate film. Create thickness distribution information.

  The invention according to claim 7 includes a step of determining an optimum pad conditioning condition based on the substrate film thickness distribution information created during polishing of the substrate and setting the pad profile parameters in real time. A polishing method according to claim 5 or 6 is provided.

  According to this configuration, during the polishing of the substrate, the substrate film thickness distribution measuring unit measures the film thickness at a plurality of locations on the substrate to create the substrate film thickness distribution information in real time, and based on this information, the conditioning controller Set the pad profile parameters of the polishing pad in real time.

  The invention according to claim 8 includes a step of detecting a surface state of the polishing pad detected during polishing of the substrate and performing pad conditioning so that the surface state of the polishing pad matches the pad profile. The polishing method according to claim 5, 6 or 7.

  According to this configuration, during the polishing of the substrate, the pad surface detection means detects the surface state of the polishing pad and creates pad surface state information in real time. Based on this information, the conditioning controller determines the surface state of the polishing pad. The pad of the polishing pad is conditioned so as to match the pad profile.

  The present invention relates to a database storing a plurality of preset pad conditioning conditions, a substrate film thickness distribution measuring means for measuring the shape of the film thickness distribution of the substrate, and a pad surface detecting means for detecting the surface state of the polishing pad. And a conditioning controller selects an optimal pad conditioning condition from the database based on the substrate film thickness distribution information created by the substrate film thickness distribution measuring means before polishing the substrate, and calculates a pad profile of the polishing pad. Since it is configured so as to be created, even when the shape of the film thickness distribution is different for each substrate, the optimum pad condition can be performed for each substrate before polishing. Therefore, it is possible to solve the problem that the substrate polished before being fed back as in the prior art cannot receive the effect of automatic control.

  Further, by setting the pad condition condition in real time during polishing, it is possible to control each substrate as needed, and any substrate can be formed to have a uniform film thickness over the entire surface in the same manner.

  In this way, a uniform film thickness can be formed over the entire surface of the substrate, so that the film thickness in a large semiconductor chip such as an image sensor used as a camera eye becomes uniform, resulting in improved performance per chip. Can be made.

  Large semiconductor chips have a high probability of including defective portions within their areas, but as in the present invention, they can be formed with a uniform film thickness over the entire surface of the substrate, thereby reducing defective products and improving yield. Can do.

Hereinafter, the polishing apparatus and the polishing method according to the present invention will be described with reference to preferred examples. Even if the shape of the film thickness distribution differs from substrate to substrate, the optimal pad condition is set for each substrate before polishing, and the pad condition conditions are set in real time during polishing, so that all substrates can be similarly treated on the entire surface of the substrate. In order to achieve the purpose of forming a uniform film thickness with
The present invention is a polishing apparatus for pressing a substrate held by a polishing head against a polishing pad on a rotating platen and supplying slurry to the polishing pad to polish the substrate from the center of the polishing pad. In a polishing apparatus comprising a pad conditioning means for conspicuous over a range up to the peripheral part, and having a conditioning controller that changes pad conditioning conditions according to the position in the polishing pad,
A database storing a plurality of preset pad conditioning conditions, a substrate film thickness distribution measuring means for measuring the shape of the film thickness distribution of the substrate, and a pad surface detecting means for detecting the surface state of the polishing pad are provided. ,
The conditioning controller selects a pad condition of a polishing pad by selecting an optimal pad conditioning condition from the database based on substrate film thickness distribution information created by the substrate film thickness distribution measuring unit before polishing the substrate. Realized by having a creation means.

  FIG. 1 is an explanatory view of a wafer polishing apparatus as an example of a substrate polishing apparatus according to the present invention. In the polishing table 10, a polishing pad 12 having the same shape is attached to the upper surface of a disk-shaped platen 11 that is rotationally driven by a motor (not shown). 11 and polishing pad 12 are formed to rotate integrally.

  The polishing head 13 provided above the platen 11 is formed in a disk shape having a smaller diameter than the platen 11, and the substrate according to the present invention is formed on the lower surface of the polishing head 13 (the back side in the drawing in the drawing). 14 is held by suction and is driven to rotate in the direction of arrow B in the figure by a motor (not shown). In this embodiment, polishing of a wafer will be described as an example of the substrate 14, but the present invention is not limited to the wafer and can be applied to polishing of other members such as a magnetic head.

  In addition, a nozzle 15 for supplying a liquid such as slurry to the upper surface of the polishing pad 12 and pad conditioning means 16 for sharpening over a range from the central portion to the peripheral portion of the polishing pad 12 are provided. The pad conditioning means 16 has an arm 16b that can pivot in the direction of arrow CC in the figure around a rotation shaft 16a, and is provided at the tip of the arm, and is a pad conditioner to which rotation and pressing force are applied. The polishing pad 12 is conditioned (dressed) by the (pad dresser) 16c.

  The turning speed of the pad conditioner 16c is freely set by the control of the conditioning controller 19 according to the position of the polishing pad 12, and the staying time of the pad conditioner 16c during turning at each position on the polishing pad 12 can be changed. It is formed as follows. Further, the pressing force applied to the pad conditioner 16 c is also changed at each position on the polishing pad 12 under the control of the conditioning controller 19.

  As described above, the pad conditioning conditions of the polishing pad 12 are freely set by controlling the staying time of the pad conditioner 16c or controlling the pressing force applied to the pad conditioner 16c. The surface state of the polishing pad 12 is detected by the pad surface detection means 17.

  Reference numeral 18 in the figure denotes a substrate film thickness distribution measuring means, and the substrate film thickness distribution measuring means 18 comprises an optical or electromagnetic measuring device and is provided on the platen 11. If the film to be polished is an oxide film, use an optical measuring instrument.If the film to be polished is other than that, use an electromagnetic measuring instrument, and compare the film thickness waveforms measured at multiple locations on the substrate, as described later. Substrate thickness distribution information creating means 20 for creating substrate film thickness distribution information.

  2 to 4 are correlation diagrams between the shape of the surface state of the polishing pad 12 and the polishing shape of the substrate 14. In each figure, FIG. (A) shows the pad profile of the polishing pad 12, the horizontal axis represents the position on the polishing pad 12, and the vertical axis represents the unevenness of the polishing pad 12 at each position. FIG. 2B shows the result when the substrate 14 is polished with the polishing pad 12 having the pad profile of FIG. 2A. The horizontal axis is the position on the substrate 14, and the vertical axis is the position of the substrate 14 at each position. This represents the polishing amount.

  For example, when the thickness of the central portion of the substrate 14 is large from the substrate film thickness distribution information measured before polishing, and the amount of polishing at the central portion is desired to be uniform in order to make the substrate 14 uniform, FIG. If the surface of the polishing pad 12 is formed in the pad profile as shown in FIG. 2A, the polishing result of the substrate 14 increases the amount of polishing at the center of the substrate 14 as shown in FIG. .

  On the other hand, when it is desired to increase the polishing amount of the peripheral portion of the substrate 14, if the surface of the polishing pad 12 is formed in a pad profile as shown in FIG. 4A, the polishing result of the substrate 14 is as shown in FIG. As shown, the amount of polishing of the peripheral portion of the substrate 14 increases. If the surface of the polishing pad 12 is formed in a pad profile as shown in FIG. 3A, the polishing result of the substrate 14 extends from the peripheral part to the central part of the substrate 14 as shown in FIG. Almost the same polishing amount can be obtained.

  The pad profile is set in advance assuming a plurality of pad conditioning conditions depending on the type of substrate, the film thickness distribution, the type of polishing pad, etc., and the plurality of pad conditioning conditions are stored in the database 21 and will be described later. As described above, the data is read from the database 21 under the control of the conditioning controller 19 before or during the polishing of the substrate.

  FIG. 5 is an explanatory view of a film thickness measurement location on the substrate 14, and FIG. 6 is an explanatory view of a waveform detected by the film thickness measuring instrument. As shown in FIG. 5, the substrate film thickness distribution measuring means 18 composed of an optical or electromagnetic measuring device, for example, a central portion A point, a peripheral portion C point of the substrate 14, an intermediate portion between the A point and the C point. The film thickness is measured at three points B. Then, as shown in FIGS. 6A to 6C, the waveform detected by the measuring device (reference S is a portion to be measured) is the same or approximates at three points of A point, B point, and C point. As described above, by changing the pad conditioning at the position of the polishing pad 12 corresponding to the points A, B, and C, it is possible to polish to a uniform film thickness over the entire surface of the substrate 14. Therefore, the more measurement points, the more reliably the film thickness can be managed.

  FIG. 7 is a flowchart showing the procedure of the polishing method according to the present invention. First, the thickness of the substrate 14 before polishing is measured by the substrate thickness distribution measuring means 18 (step 100), and the thickness distribution information of the substrate 14 is created by the substrate thickness distribution information creating means 20 (step 101). Further, the correlation information between the optimum pad surface characteristic and the polishing amount distribution is selected and read from the database 21 based on the substrate film thickness distribution information from a plurality of pad conditioning conditions stored in advance (step 102). Optimal parameters are set to determine pad conditioning conditions (step 103).

  Then, the pad profile creation means 22 provided in the conditioning controller 19 creates a pad profile of the polishing pad 12 according to the determined pad conditioning conditions, and the surface condition of the polishing pad 12 is monitored by the pad surface detection means 17. (Step 104), pad conditioning is executed so that the surface state of the polishing pad 12 matches the optimal pad profile (Step 105), and pad conditioning before polishing of the substrate 14 is completed (Step 106).

  Subsequently, polishing of the substrate 14 is started (step 107), and the substrate film thickness distribution state during polishing is monitored in real time (step 108), and the surface state of the polishing pad is monitored during polishing (step 108). 109), detect whether the substrate thickness distribution during polishing is uniform, and if the substrate thickness is not uniform, correct the initial pad conditioning conditions and determine new pad conditioning conditions. (Step 110), pad conditioning is executed (Step 111).

  When polishing of the substrate 14 is completed, the film thickness of the substrate 14 is measured (step 112), and post-polishing substrate film thickness distribution information is created (step 113), and polishing amount distribution information is created (step 114).

  As described above, based on the substrate film thickness distribution information created before polishing the substrate 14, the optimum pad conditioning conditions are determined, the pad profile of the polishing pad 12 is created, and the pad conditioning is executed. Since the substrate 14 is polished while performing pad conditioning while monitoring the substrate film thickness distribution state, even when the shape of the film thickness distribution is different for each substrate, control can be performed for each substrate at any time, Any substrate can be formed to have a uniform film thickness over the entire surface in the same manner.

  It should be noted that the present invention can be variously modified without departing from the spirit of the present invention, and the present invention naturally extends to the modified ones.

Explanatory drawing which shows the structural example of the substrate polishing apparatus which concerns on this invention. The correlation figure of the shape of the surface state of a polishing pad, and the grinding | polishing shape of a board | substrate. The correlation figure of the shape of the surface state of a polishing pad, and the grinding | polishing shape of a board | substrate. The correlation figure of the shape of the surface state of a polishing pad, and the grinding | polishing shape of a board | substrate. Explanatory drawing of the film thickness measurement location in a board | substrate. Explanatory drawing of the detection waveform by a film thickness measuring device. The flowchart which shows the procedure of the grinding | polishing method.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Polishing table 11 Platen 12 Polishing pad 13 Polishing head 14 Substrate 15 Nozzle 16 Pad conditioning means 16a Rotating shaft 16b Arm 16c Pad conditioner 17 Pad surface detection means 18 Substrate film thickness distribution measuring means 19 Conditioning controller 20 Substrate film thickness distribution information creation Means 21 Database 22 Pad profile creation means

Claims (8)

A polishing apparatus that presses a substrate held by a polishing head against a polishing pad on a rotating platen and supplies slurry to the polishing pad to polish the substrate, from the central part to the peripheral part of the polishing pad In a polishing apparatus comprising a conditioning controller that changes the pad conditioning condition according to the position in the polishing pad, and has pad conditioning means for sharpening over a range of
A database storing a plurality of preset pad conditioning conditions, a substrate film thickness distribution measuring means for measuring the shape of the film thickness distribution of the substrate, and a pad surface detecting means for detecting the surface state of the polishing pad are provided. ,
The conditioning controller selects a pad condition of a polishing pad by selecting an optimal pad conditioning condition from the database based on substrate film thickness distribution information created by the substrate film thickness distribution measuring unit before polishing the substrate. A polishing apparatus comprising a creating means.   The substrate film thickness distribution measuring means includes substrate film thickness distribution information creating means for creating film thickness distribution information by comparing film thickness measurement waveforms measured at a plurality of locations on the substrate. The polishing apparatus according to claim 1.   The polishing apparatus according to claim 1 or 2, wherein the substrate film thickness distribution measuring means comprises an optical or electromagnetic measuring device, and the measuring device is provided on the platen.   The conditioning controller has means for determining optimum pad conditioning conditions and setting the parameters of the pad profile based on substrate film thickness distribution information and polishing pad surface state information created during substrate polishing. The polishing apparatus according to claim 1, 2 or 3. A polishing method in which a substrate held by a polishing head is pressed against a polishing pad on a rotating platen and a slurry is supplied to the polishing pad to polish the substrate, from the central portion to the peripheral portion of the polishing pad In the polishing method, including the step of performing pad conditioning for sharpening over the range of, and changing the pad conditioning conditions according to the position in the polishing pad,
Set multiple pad conditioning conditions in advance and store them in the database, measure the shape of the film thickness distribution before polishing the substrate, create substrate film thickness distribution information,
A pad profile of the polishing pad is created by selecting the optimum pad conditioning condition from the database based on the substrate film thickness distribution information,
A polishing method characterized by performing automatic control so as to polish a substrate by performing pad conditioning according to the pad profile.   6. The polishing method according to claim 5, wherein the substrate film thickness distribution information includes a step of comparing the film thickness waveforms measured at a plurality of locations on the substrate.   6. A step of determining an optimal pad conditioning condition based on substrate film thickness distribution information created during polishing of the substrate and setting the parameters of the pad profile in real time. Or the polishing method of 6.   The method includes the steps of detecting a surface state of the polishing pad detected during polishing of the substrate and performing pad conditioning so that the surface state of the polishing pad matches the pad profile. Item 8. The polishing method according to Item 5, 6 or 7.

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