KR101134586B1 - Wafer carrier and monitoring apparatus for polishing of semiconductor wafer - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wafer carrier for semiconductor wafer polishing and a monitoring device, wherein the disclosed wafer carrier includes a plurality of piezoelectric sensors for sensing temperature changes and acoustic waves during the polishing process, and the monitoring device includes a plurality of piezoelectric sensors from the piezoelectric sensor during the polishing process. A polishing information acquisition unit for obtaining a plurality of pieces of polishing information corresponding to a local polishing position of a data storage unit, a data storage unit storing polishing situation reference data corresponding to elastic waves and volume changes detected by the piezoelectric sensor, and polishing information obtaining unit A controller for determining the polishing situation for the local polishing position during the polishing process according to the comparison result of the polishing information input from the polishing state reference data stored in the data storage unit, and the polishing situation for the local polishing position determined by the controller Polishing status display unit for outputting the external to the polishing process Locally detects the polishing situation of the wafer and displays the polishing situation of the wafer externally, so that the polishing situation can be seen in real time during the wafer polishing process, and can be used as a useful information for developing polishing processes and abrasives and polishing pads. There is an advantage to this.

CMP, wafer carrier, monitoring, piezoelectric sensor

Description

Wafer carrier and monitoring device for semiconductor wafer polishing {WAFER CARRIER AND MONITORING APPARATUS FOR POLISHING OF SEMICONDUCTOR WAFER}

1 is a block diagram of a chemical mechanical polishing apparatus according to the prior art,

2 is a configuration diagram of a wafer carrier included in the polishing apparatus of FIG. 1;

3 is a configuration diagram showing a first embodiment of a wafer carrier for polishing a semiconductor wafer according to the present invention;

4 is a plan view showing an embodiment of the polishing situation detection disk included in the wafer carrier of FIG.

5 is a configuration diagram showing a second embodiment of a wafer carrier for polishing a semiconductor wafer according to the present invention;

6 is a block diagram of a semiconductor wafer polishing monitoring apparatus according to the present invention.

<Explanation of symbols for the main parts of the drawings>

100: wafer carrier 150: polishing situation detection disk

155, 175: piezoelectric sensor 170: airbag

210: polishing information acquisition unit 230: control unit

250: data storage unit 270: polishing situation display unit

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to semiconductor wafer polishing, and more particularly, to detect elastic waves caused by temperature, stress, and defects when polishing a semiconductor wafer through a chemical-mechanical polishing (CMP) process. The present invention relates to a wafer carrier and a monitoring device for polishing a semiconductor wafer, by which the polishing situation of the semiconductor wafer can be monitored by analyzing a detection waveform.

The semiconductor device has a unit structure having various structures disposed on a semiconductor substrate, an insulating film for electrically insulating them, and a wiring structure for forming a circuit by electrically connecting the unit devices. The semiconductor device is manufactured by a combination of complex unit processes such as a deposition process, a photographic process, an ion implantation process, and an etching process. Among these semiconductor manufacturing processes, the CMP process is applied to the planarization of the interlayer insulating film, the formation of shallow trench isolation (STI), the formation of tungsten plugs, and the damascene process for copper and polysilicon films.

In the CMP process, the polishing pad containing the slurry is brought into contact with the polishing target surface of the wafer, and then subjected to a constant pressure, and the chemical and physical etching are simultaneously performed by rotating the polishing pad and the wafer at a predetermined speed.

1 is a block diagram of a CMP apparatus according to the prior art, and FIG. 2 is a block diagram of a wafer carrier included in the polishing apparatus of FIG.

1 and 2, in the conventional CMP apparatus, a polishing pad 12 is attached to an upper portion of the rotating platen 10 rotating about a vertical center axis. The carrier 20 supporting the wafer W or the polishing object is located above the rotating platen 10 and centered about the vertical center axis of the carrier 20 by a spindle device supported by the polishing arm (not shown). Rotate At this time, the bottom surface of the semiconductor wafer W supported by the carrier 20 is disposed in a manner opposite to the polishing pad 12. The carrier 20 is lowered on the surface of the rotating platen 10 to apply a load and rotate in the same direction as the direction of rotation of the rotating platen 10, while supplying the abrasive 14 to the surface of the polishing pad 12. Polish the surface of (W).

The abrasive 14 is continuously supplied to the top of the polishing pad 12 to improve the accuracy of polishing and polishing rate of the wafer W, and when pad conditioning by the pad conditioner 30 is performed after wafer polishing is finished. Washing water is supplied to the center portion of the polishing pad 12 to clean the abrasive residues remaining in the polishing pad 12.

The carrier 20 includes a base plate 23 connected to the lower end side of the rotation shaft 21, an annular retainer ring 25 provided along the lower edge of the base plate 23, and an annular retainer ring 25. , And a carrier film 29 attached to the base plate 23 inwardly of the support ring 25.

The carrier film 29 is provided with a plurality of vacuum nozzles 27, which are one-way suction means, uniformly as a whole, and sucks and mounts the wafer W by the suction force of the vacuum nozzle 27, and the mounted wafer W Is located inside the support ring 25.

The support ring 25 is a ring shape slightly larger than the wafer W to prevent the wafer W from being pushed out while being polished.

In the CMP process by the CMP apparatus configured as described above, it is necessary to finish polishing at a predetermined position on the semiconductor wafer after the semiconductor wafer is polished for a certain period of time. For example, it may be desirable to leave an insulating layer, such as SiO ₂ , over a metal wire of Cu or Al (which is called an interlayer film because the metal layer is formed on the insulating layer in a subsequent process). If the semiconductor wafer is polished more than necessary, the lower metal film is exposed to the surface. Thus, the polishing process must be finished to leave an interlayer film of a predetermined thickness.

According to another process, a predetermined pattern of wiring grooves is formed on the surface of the semiconductor wafer. After the wiring groove is filled with Cu or Cu alloy, unnecessary portions are removed from the surface of the semiconductor wafer by the CMP process. When the Cu layer is polished by the CMP process, it is necessary to selectively remove the Cu layer from the semiconductor wafer, leaving only the Cu layer formed in the wiring groove. Specifically, the Cu layer should be removed to expose an insulating film such as SiO ₂ in a region other than the wiring groove.

In this case, when the Cu layer in the wiring groove is excessively polished together with the insulating layer, the circuit resistance increases and a large loss occurs because the entire semiconductor wafer must be discarded. On the contrary, when the Cu layer is insufficiently polished and remains on the insulating layer, the circuits are not separated well and cause a short circuit. Therefore, the production cost increases because the Cu layer must be polished again.

Therefore, a polishing state monitoring technique is known which measures the intensity of light reflected by the optical sensor and detects the end point of the CMP process based on the measured intensity of reflected light. As an example, Korean Patent Publication No. 10-2005-0050106 discloses " And a polishing apparatus and a polishing state monitoring apparatus.

The polishing state monitoring device of Patent Publication No. 10-2005-0050106 includes a light emitting unit applying light from a light source to a surface of a workpiece being polished, the light receiving unit receiving reflected light from the surface of the workpiece, and the spectroscope unit receiving the light receiving unit. Splits the reflected light received by the plurality of light rays having respective wavelengths, the light receiving element accumulates the detected light rays as electrical information, and the spectral data generator reads the electrical information accumulated by the light receiving element, thereby reflecting the spectrum of the reflected light. Generates data, and the processor calculates a predetermined characteristic value on the surface of the workpiece based on the spectral data generated by the spectral data generator.

Such a polishing state monitoring apparatus can terminate polishing of the semiconductor wafer at an appropriate end point during the CMP process by the CMP apparatus.

Meanwhile, in the wafer polishing process using the CMP apparatus, defects such as scratches are generated due to the mechanical polishing characteristics of the CMP apparatus. Among these, micro scratches are low in depth and can be sufficiently removed in a subsequent buffing or cleaning process.

However, in addition to such micro scratches, macro scratches, which are sometimes fatally generated on the wafer surface by large particles, remain unremoved even by the buffing polishing process and the cleaning process, and the scratch defects caused by the CMP polishing process result in wafer yield. It acts as a cause of deterioration.

As a technique for preventing the yield resistance of such a semiconductor wafer, Korean Patent Laid-Open Publication No. 10-2005-0050189 discloses "a wafer polishing apparatus for detecting a wafer defect and a control method thereof".

In the wafer polishing apparatus for detecting wafer defects, the light source emits light on the wafer surface while the wafer surface is polished, the light detector detects light reflected on the wafer surface, and the CMP control unit. Determines whether the wafer polishing process using the CMP is normal or abnormal according to the signal detected by the light detector. As a result, by detecting the light reflected from the wafer surface, it is possible to determine whether or not there is a scratch or more of the size set as the topology of the wafer surface, thereby preventing the wafer yield from being lowered due to the micro scratches remaining without being removed in the buffing polishing process or the cleaning process. can do.

However, the above-described conventional wafer defect detection technique can confirm whether or not scratches are generated on the wafer polishing surface when polishing the semiconductor wafer, but the position where the scratches were generated could not be accurately determined. The temperature distribution and the stress distribution of the wafer could not be known at all.

If the path of abrasive particles moving, where the particles are broken, and where scratches occur during CMP process can be known, it can be used as a very useful information for developing polishing process and abrasives and polishing pads. If the temperature distribution and the stress distribution at each position of the wafer can be known in real time, it is obvious that this information can be used as very useful information for developing a polishing process, an abrasive and a polishing pad.

Therefore, a situation has been given to the development of a new monitoring device that can locally monitor the polishing of the wafer during the CMP process.

The present invention is a result of research efforts in accordance with such a conventional development problem, the polishing information by placing a plurality of polishing state detection sensor in the wafer carrier to locally detect the polishing state of the wafer during the polishing process by the CMP apparatus It is an object of the present invention to provide a monitoring device for polishing a semiconductor wafer which displays the polishing situation of the wafer to the outside based on the obtained after the acquisition.

Another object of the present invention is to provide a polishing state detection sensor that can locally detect the polishing state of the wafer during the polishing process by the CMP apparatus, and the wafer and the wafers on which the polishing state detection adsorption is mounted on a plurality of disks. It is providing the wafer carrier of the structure added between the carrier film carried by adsorption | suction installation.

It is still another object of the present invention to provide a polishing state detection sensor capable of locally sensing a polishing state of a wafer during a polishing process by a CMP apparatus. SUMMARY OF THE INVENTION An object of the present invention is to provide a wafer carrier having a structure in which a plurality of polishing condition detection sensors are arranged in an airbag that is balanced in the entire wafer.

As one aspect of the present invention for realizing the above objects, the monitoring apparatus for semiconductor wafer polishing monitors a process of polishing the wafer by rotation of a rotating platen with a polishing pad and a wafer carrier on which a semiconductor wafer is mounted. The apparatus of claim 1, wherein the wafer carrier comprises a piezoelectric element, and includes a plurality of piezoelectric sensors for sensing a change in volume of the acoustic wave and the piezoelectric element generated at a local polishing position of the wafer during the polishing process. The polishing information obtaining unit may acquire polishing information from the plurality of piezoelectric sensors, a data storage unit storing polishing situation reference data corresponding to the elastic wave and volume change detected by the piezoelectric sensor, and the polishing information obtaining unit. The polishing information input from the and stored in the data storage unit A control unit for determining the polishing situation for the local polishing position during the polishing process according to the comparison result of the situation situation reference data, and a polishing situation display unit for outputting the polishing situation for the local polishing position determined by the controller to the outside It includes.

According to another aspect of the present invention, a wafer carrier for polishing a semiconductor wafer is a wafer carrier for polishing a semiconductor wafer by rotating the drive after mounting the semiconductor wafer on a polishing pad and having a base plate connected to the lower end side of the rotating shaft. A support film provided along the lower edge of the base plate, a carrier film attached to the base plate by the inside of the support ring, and having a plurality of one-way suction means for adsorbing the wafer, between the adsorbed wafer and the carrier film. It includes a polishing situation detecting disk for detecting the temperature change and the acoustic wave during the polishing process through a plurality of polishing situation detection means disposed in the.

In still another aspect of the present invention, a wafer carrier for semiconductor wafer polishing is a wafer carrier for attaching a semiconductor wafer, placing the semiconductor wafer on a polishing pad, and polishing the semiconductor wafer through rotational driving. The base plate is connected to the lower end side of the rotating shaft. A support ring provided along the lower edge of the base plate, an air bag positioned inside the support ring to maintain a constant pressure and supply pressure from the top to the entire lower wafer in a balanced manner. It includes a plurality of polishing state detection means for detecting the temperature change and the acoustic wave during the polishing process.

There may be a plurality of embodiments of the present invention, hereinafter with reference to the accompanying drawings will be described in detail a preferred embodiment. Through this embodiment will be able to better understand the objects, features and advantages of the present invention.

3 is a block diagram showing a first embodiment of a wafer carrier for polishing a semiconductor wafer according to the present invention, and FIG. 4 is a plan view showing an embodiment of a polishing situation detecting disk included in the wafer carrier of FIG. 3.

As shown in FIG. 3, the wafer carrier 100 according to the first embodiment of the present invention includes a base plate 103 connected to the lower end side of the rotation shaft 101 and a lower edge of the base plate 103. The wafer (W) by the suction force of the annular support ring 105 and the vacuum nozzle 107, which is attached to the base plate 103 side inside the support ring 105 and uniformly provided in a uniform number, in one direction Temperature change during the polishing process through the carrier film 109 for adsorption mounting and the piezoelectric sensor 155 disposed between the adsorption-mounted wafer W and the carrier film 109 and provided with a plurality of polishing state sensing means. It comprises a polishing situation detection disk 150 for detecting the acoustic wave.

As shown in FIGS. 3 and 4, the polishing situation detecting disk 150 has a contact surface with the carrier film 109 in arranging three or more piezoelectric sensors 155 on the polishing situation detecting disk 150. In other words, the transient reaction of the piezoelectric sensor 155 is suppressed by being disposed on a non-contact surface with the wafer W so as not to directly contact the wafer W that is adsorbed and mounted.

According to the wafer carrier 100 according to the first embodiment of the present invention configured as described above, the wafer platen 100 is lowered on the surface of the platen 10 as in the prior art, and the platen 10 is loaded in a state where a load is applied thereto. The surface of the wafer W is polished while the abrasive is supplied to the surface of the polishing pad 12.

Here, the polishing situation detecting disk 150 detects a temperature change and an acoustic wave during the polishing process through the piezoelectric sensor 155, which is provided with a plurality of polishing situation sensing means. A seismic wave can be detected.

In detail, the piezoelectric sensor 155 detects an elastic wave generated by a change in stress caused by contact or collision between the abrasive particles and the wafer and friction, and in the case of a temperature change, the piezoelectric sensor 155 is detected. The volume of the piezoelectric element is changed to detect it.

In this case, as shown in FIG. 4, since the polishing situation detecting disk 150 includes a plurality of piezoelectric sensors 155, each piezoelectric sensor 155 acquires polishing information of a local position corresponding to the placement position. will be.

6 is a block diagram of a semiconductor wafer polishing monitoring apparatus according to the present invention.

As illustrated in FIG. 6, in the monitoring apparatus of the present invention, the polishing information acquisition unit 210 acquires a plurality of pieces of polishing information corresponding to a plurality of local polishing positions from the piezoelectric sensor 155 installed in the wafer carrier during the CMP process. And a data storage unit 250 in which the polishing condition reference data corresponding to the elastic wave and the volume change detected by the piezoelectric sensor 155 is stored, and the polishing information and the data storage unit input from the polishing information obtaining unit 210 ( According to a comparison result of the polishing situation reference data stored in 250, the control unit 230 determines the polishing situation for the local polishing location during the CMP process, and the polishing situation for the local polishing location determined by the control unit 230. It is comprised including the polishing situation display part 270 which outputs to the exterior.

In the monitoring apparatus of the present invention configured as described above, a process of displaying a local polishing situation during the CMP process will be described.

First, the plurality of piezoelectric sensors 155 disposed on the polishing situation detecting disk 150 are configured to detect or form a piezoelectric sensor 155 due to a change in stress generated by contact or collision between abrasive particles and a wafer and a change in stress caused by friction. When the volume change of the piezoelectric element is detected, it is converted into an electrical signal and provided to the polishing information acquisition unit 210.

Thereafter, the polishing information acquisition unit 210 provides the polishing state detection data provided from the piezoelectric sensor 155 to the controller 230.

Then, the controller 230 compares the polishing situation reference data stored in the data storage unit 250 with the polishing situation detection data provided from the piezoelectric sensor 155, and corresponds to a local corresponding to the position where the piezoelectric sensor 155 is disposed. Determine the polishing situation of the phosphorus position. In other words, by analyzing the contact or collision between the abrasive particles and the wafer, the stress change caused by friction, and the temperature change causing the volume change, the movement path, particle breakage location, scratch occurrence position, wafer temperature distribution and stress distribution of the abrasive particles are analyzed. do.

Next, the controller 230 provides the polishing state display information on the corresponding position of the piezoelectric sensor 155 to the polishing state display unit 270, and the polishing state display unit 270 provides the wafer according to the control signal of the controller 230. The polishing situation (movement path of abrasive particles, particle breakdown position, scratch occurrence position, wafer temperature distribution and stress distribution, etc.) according to the local position during the polishing process is output to the outside in real time.

5 is a block diagram showing a second embodiment of a wafer carrier for polishing a semiconductor wafer according to the present invention. In designating reference numerals in FIG. 5, the same components have the same reference numerals as compared with the wafer carrier according to the first embodiment shown in FIG. 3.

3 and 5, the carrier film 109 and the polishing situation detecting disk 150 according to the first embodiment are replaced with the airbag 170 in the second embodiment, and the wafer of the airbag 170 is replaced with the airbag 170. It can be seen that a plurality of piezoelectric sensors 175 are disposed on the inner wall of the contact surface with W). Here, the piezoelectric sensor 175 is a polishing situation detection means for detecting the temperature change and the acoustic wave during the polishing process, and has the same function as the piezoelectric sensor 155 of the first embodiment, the air bag 170 has a constant pressure inside the air bag 170 It serves to supply the pressure applied from the upper part to maintain the entire balance of the lower wafer (W). In particular, when the airbag 170 is made of a material such as polyimide having elasticity and flexibility, elastic waves generated during the wafer polishing process are transmitted to the piezoelectric sensor 175 in real time.

It has been described so far limited to one embodiment of the present invention, it is obvious that the technology of the present invention can be easily modified by those skilled in the art.

For example, the piezoelectric sensors 155 and 175 disposed on the polishing situation detecting disk 150 or the airbag 170 may arrange various types of sensors to detect elastic waves of various frequency bands if necessary.

It is to be understood that such modified embodiments are naturally included in the technical spirit described in the claims of the present invention.

As described above, the present invention obtains polishing information by placing a plurality of piezoelectric sensors on the wafer carrier which can locally detect the polishing state of the wafer during the polishing process by the CMP apparatus, thereby obtaining the polishing state of the wafer to the outside. In this way, the polishing process, abrasives and polishing pads, etc. can be developed by providing real-time knowledge of polishing conditions such as movement paths of abrasive particles, particle breakdown locations, scratch generation locations, wafer temperature distributions and stress distributions during the wafer polishing process. It has the effect of making it available as useful information.

Claims (11)

An apparatus for monitoring a process of polishing a wafer by rotation of a rotating platen attached with a polishing pad and a wafer carrier on which a semiconductor wafer is mounted, The wafer carrier, A plurality of piezoelectric sensors made of a piezoelectric element, for detecting the volume change of the acoustic wave and the piezoelectric element generated at the local polishing position of the wafer during the polishing process Including; The monitoring device, A polishing information obtaining unit obtaining polishing information from the plurality of piezoelectric sensors; A data storage unit for storing the polishing situation reference data corresponding to the elastic wave and the volume change detected by the piezoelectric sensor; A controller which determines a polishing situation for a local polishing position during the polishing process according to a comparison result of the polishing information input from the polishing information obtaining unit and the polishing situation reference data stored in the data storage unit; Polishing situation display unit for outputting the polishing situation for the local polishing position determined by the controller to the outside Monitoring device for semiconductor wafer polishing comprising a. The method of claim 1, In the wafer carrier, a disk having a plurality of piezoelectric sensors is disposed on a contact surface with the wafer. Monitoring device for semiconductor wafer polishing, characterized in that. The method of claim 2, The piezoelectric sensor is provided on a non-contact surface of the disk with the wafer. Monitoring device for semiconductor wafer polishing, characterized in that. The method of claim 1, In the wafer carrier, an airbag having a plurality of piezoelectric sensors is disposed on a contact surface with the wafer. Monitoring device for semiconductor wafer polishing, characterized in that. The method of claim 4, wherein The piezoelectric sensor is provided on the inner wall of the contact surface of the airbag with the wafer Monitoring device for semiconductor wafer polishing, characterized in that. A wafer carrier for mounting and placing a semiconductor wafer on a polishing pad and polishing the semiconductor wafer by rotational driving, A base plate connected to the lower end of the rotating shaft, A support ring provided along a lower edge of the base plate; A carrier film attached to the base plate side to the inside of the support ring to suck and mount the wafer by one-way suction means; A polishing situation sensing disk disposed between the suction-mounted wafer and the carrier film to sense temperature changes and acoustic waves during the polishing process through a plurality of polishing situation sensing means. A wafer carrier for polishing a semiconductor wafer comprising a. The method of claim 6, The polishing state detecting means is a piezoelectric sensor Wafer carrier for polishing a semiconductor wafer, characterized in that. The method of claim 7, wherein The piezoelectric sensor is provided on a non-contact surface of the disk with the wafer. Wafer carrier for polishing a semiconductor wafer, characterized in that. A wafer carrier for mounting and placing a semiconductor wafer on a polishing pad and polishing the semiconductor wafer by rotational driving, A base plate connected to the lower end of the rotating shaft, A support ring provided along a lower edge of the base plate; An air bag positioned inside the support ring to maintain a constant pressure and supply pressure from the upper part to the entire lower wafer in a balanced manner; Polishing situation sensing means provided in the airbag in plurality in order to detect temperature changes and acoustic waves during the polishing process A wafer carrier for polishing a semiconductor wafer comprising a. The method of claim 9, The polishing state detecting means is a piezoelectric sensor Wafer carrier for polishing a semiconductor wafer, characterized in that. 11. The method of claim 10, The piezoelectric sensor is provided on the inner wall of the contact surface with the wafer Wafer carrier for polishing a semiconductor wafer, characterized in that.

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