KR20160103710A

KR20160103710A - Chemical mechanical polishing apparatus

Info

Publication number: KR20160103710A
Application number: KR1020150026393A
Authority: KR
Inventors: 안준호; 최광락; 조문기
Original assignee: 주식회사 케이씨텍
Priority date: 2015-02-25
Filing date: 2015-02-25
Publication date: 2016-09-02

Abstract

The present invention relates to a chemical mechanical polishing apparatus, and more particularly, to a chemical mechanical polishing apparatus for polishing a polishing layer of a wafer in which the device is disposed at an interval in order to manufacture a plurality of devices, An abrasive platen that is wound on the upper surface and rotates; And a light sensor configured to detect a thickness of the polishing layer of the wafer by irradiating light onto the polished surface of the wafer, wherein the spot size of the light is formed to a diameter larger than at least one of a width and a length of the device, Provided is a chemical mechanical polishing apparatus which accurately detects the thickness of a polishing layer from a received light signal incident on and reflected by an enlarged area.

Description

{CHEMICAL MECHANICAL POLISHING APPARATUS}

The present invention relates to a chemical mechanical polishing apparatus, and more particularly, to a chemical mechanical polishing apparatus that solves a measurement error due to the position of light to be irradiated to measure the thickness of a wafer polishing layer during a chemical mechanical polishing process.

Generally, a chemical mechanical polishing (CMP) process is a process in which a surface of a substrate is flattened to a predetermined thickness by performing mechanical polishing while rotating a substrate such as a wafer in contact with a rotating polishing plate to be.

For this purpose, the chemical mechanical polishing apparatus includes a polishing head 11 for holding a wafer W on a polishing pad 11 (see FIG. 1) while rotating the polishing pad 11 in a state of covering the polishing pad 11 on the polishing table 10, ) While rotating the wafer while pressing the wafer surface flat. To this end, a conditioner 30 is provided for reforming the conditioning disk 31 pressing the surface of the polishing pad with a predetermined pressing force 30F while rotating the polishing pad 30r, and performing chemical polishing on the surface of the polishing pad 11 The slurry is supplied through the slurry supply unit 40.

At this time, since the polishing layer thickness of the wafer on which the chemical mechanical polishing process is performed must be stopped while reaching the final target thickness, the thickness of the wafer polishing layer during the chemical mechanical polishing process is continuously monitored by the thickness detection sensor 50 do. In some cases, the polishing layer thickness distribution of the wafer during the chemical mechanical polishing process may be measured by the thickness detection sensor 50, and the thickness distribution may be controlled by the control unit 70.

The thickness sensing sensor 50 may be provided differently depending on the type of the wafer polishing layer Le, but in the case of an optical sensor, the wafer polishing layer Le may be applied to both the oxide layer and the metal layer. When the wafer polishing layer Le is an oxide layer, the thickness distribution of the wafer polishing layer can be obtained from the initial polishing stage from the thickness detecting sensor 50 formed of the optical sensor, and at the same time, the polishing end point can be sensed. When the wafer polishing layer Le is a metal layer, the polishing end point can be detected.

That is, as shown in FIG. 2, after the optical signal Li is irradiated to the polishing layer Le when the wafer W is rotated together with the polishing pad 11 and passes under the wafer, And receives the light receiving signal Lo and senses the thickness of the polishing layer Le of the wafer W by transferring the light receiving signal Lo to the control unit 70. [ 5, the optical signal Li emitted from the optical sensor 50 passes through the lower side of the wafer W and is received by the light receiving signal The thickness or the thickness distribution of the abrasive layer is obtained by the interference signal or the phase difference of the light reception signal Lo2 reflected from the inner boundary Si passing through the polishing layer Le and the polishing layer Le.

However, as shown in Figs. 3 and 4, the wafer W used for manufacturing the semiconductor element or the package is formed such that the inner interface Si of the polishing layer Le is not flat and the projections and depressions 99 are formed . That is, the area of the device D used for fabricating the semiconductor device or the package is formed with the projections and depressions 99 and the sidewall B of the device D is a cutting line for dividing the devices D, respectively It is not mounted separately and forms a flat surface.

5, when the light signal Li having a diameter of approximately 10 to 20 占 퐉 passes through the surface of the polishing layer Le and irradiates the sate region B, the light-receiving signals Lo1 and Lo2 become The optical signal Li passes through the surface of the abrasive layer Le and reaches the uneven portion 99 of the device 99. In this case, There is a problem in that the thickness of the abrasive layer Le of the wafer W can not be accurately measured because a part of the light receiving signals Lo1 and Lo2 is lost when the irradiation is performed.

Thus, although the optical signal Li is attempted to be irradiated only to the sidewall B where the device D is not formed, the optical signal Li is reflected in the sidewall B ) Is very difficult to control so that it can not be realistically realized.

SUMMARY OF THE INVENTION The present invention has been made to overcome the above-mentioned problems, and it is an object of the present invention to solve the measurement error according to the position of the irradiated light for measuring the thickness of the wafer polishing layer during the chemical mechanical polishing process.

It is therefore an object of the present invention to precisely measure the thickness of the abrasive layer according to the position of the wafer even if the optical sensor does not perform complicated control to irradiate the optical signal only at a specific position.

In order to achieve the above-mentioned object, the present invention provides a chemical mechanical polishing apparatus for polishing an abrasive layer of a wafer in which the device is disposed at intervals so as to manufacture a plurality of devices, An abrasive platen on which an abrasive pad is coated and rotated; And a light sensor formed on the polishing surface of the wafer to detect the polishing layer thickness of the wafer by irradiating light with a spot size larger than at least one of a width and a length of the device To thereby provide a chemical mechanical polishing apparatus.

This is because the optical spot size of the optical sensor that receives the optical signal to the polishing layer of the wafer and receives the light receiving signal reflected from the wafer is made larger than any one of the width and the length of the device, So that it is possible to accurately detect the thickness of the film.

In other words, since the spot size of the optical signal from the optical sensor is enlarged larger than that of the device, the light receiving signal reflected by the wafer polishing layer constantly includes the light receiving signal reflected by the area where the device is located. The amount of signals which are lost or diffused in the light receiving signal irrespective of the irradiation position of the optical signal is uniformed and the incident light is incident on the polishing layer in an enlarged area An advantageous effect of accurately sensing the thickness of the polishing layer from the reflected light receiving signal can be obtained.

To this end, it is preferable that the spot of the optical sensor has a shape capable of positioning one device in the spot. For example, the spot diameter of the optical sensor may be greater than one inch. Device.

Also, the width of the optical signal is determined by a size of the width of the device and the width of the searched area, and the length of the optical signal may be determined by a length of the device and a length of the searched area. In this case, at least one device and one short edge region are simultaneously located in the spot, regardless of the position of the optical signal on the wafer.

That is, the width of the optical signal is determined to be an integer multiple of the width of the device and the width of the sate region, and the length of the optical signal is determined to be an integer multiple of the length of the device and the length of the sate region. It is ideal to lose. Thereby, the spot emitted from the optical sensor includes a predetermined number of devices and a searched area, so that the amount of the light-receiving signal lost or diffused in the device can always be kept constant.

For this purpose, the optical signal may be formed in a rectangular shape similar to the device form instead of the circular form. More preferably, the optical signal is a rectangle having a shape resembling a shape in which a short side region adjacent to the device is combined in the width direction and the longitudinal direction.

The optical sensor may be provided to measure the thickness of the wafer polishing layer while rotating together with the polishing pad. The optical sensor may be fixed to the bottom surface of the through hole formed in the polishing pad, It can also be installed to measure.

The control unit of the chemical mechanical polishing apparatus receives the light receiving signal of the optical sensor and averages the light receiving signal to sense the thickness of the polishing layer so that the thickness of the polishing layer can be accurately Can be detected.

As described above, according to the present invention, an optical spot size of an optical sensor that receives an optical signal to a polishing layer of a wafer and receives a light receiving signal reflected from the wafer is further enlarged in comparison with the size of the device, Even when a part of the optical signal is lost or diffused in the area where the device is located and is not received by the photosensor, the reflected light is received regardless of the irradiation position of the optical signal, It is possible to obtain an advantageous effect of accurately detecting the thickness of the abrasive layer from the received light signal incident on the abrasive layer and reflected by the enlarged area.

In order to measure the thickness of the wafer polishing layer during the chemical mechanical polishing process, the present invention can solve the error in which the measured value differs depending on the position of the light irradiated to the polishing layer, It is possible to obtain an advantageous effect that the thickness of the polishing layer can be accurately measured according to the position of the wafer even if the position of the wafer is not complicatedly controlled.

1 is a front view showing a general chemical mechanical polishing apparatus,
2 is an enlarged view of a portion 'A' in FIG. 1,
3 is a view showing a configuration of a wafer,
FIG. 4 is an enlarged view of a portion 'B' in FIG. 3,
5 is a sectional view taken along line V-V in Fig. 4,
6 is a front view showing a configuration of a chemical mechanical polishing apparatus according to an embodiment of the present invention;
Fig. 7 is a plan view of Fig. 6,
8 is a view showing the trajectory of a spot of an optical signal of the optical sensor reaching the wafer,
FIG. 9A is a partially enlarged view of FIG. 8,
FIG. 9B is a view showing a state where a spot of an optical signal reaches a wafer according to another embodiment of the present invention; FIG.
10 is a cross-sectional view taken along the line XX of Fig. 9A.

Hereinafter, a chemical mechanical polishing apparatus 100 according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings. In the following description, well-known functions or constructions are not described in detail to avoid obscuring the subject matter of the present invention.

A chemical mechanical polishing apparatus 100 or 100 'according to an embodiment of the present invention includes a polishing table 10 on which a polishing pad 11 is brought into contact so that the polishing surface of the wafer W is polished, And a conditioning disk 31 rotating in contact with the surface of the polishing pad 11 while being pressed against the surface of the polishing pad 11, A conditioner 30 for modifying the pad 11, a slurry supply unit 40 for supplying a slurry for chemical polishing of the wafer W, a polishing pad 11 fixedly positioned on the bottom surface of the conditioning disk 31, An optical sensor 50 used for sensing the thickness of the polishing layer Le by receiving the reflected light reception signal Lo by irradiating the polishing layer Le of the wafer W with the optical signal Li, (Including the thickness fluctuation amount) of the polishing pad 11 and the thickness of the polishing pad 11 (including the thickness variation) from the light receiving signal received by the optical sensor 50 And a control unit 70 for sensing the thickness (including the thickness variation) of the wafer polishing layer Le.

The polishing table 10 is rotationally driven in a state in which the polishing pad 11 is put on the upper surface. As shown in FIG. 8, the polishing table 10 may be provided with a through hole through which a signal from the optical sensor 50 passes, and the optical sensor 50 may be provided on the polishing platen 10 so as to rotate together with the polishing pad 11. When the optical sensor 50 rotates together with the polishing pad 11, the control circuit of the control unit 70 may rotate together with the polishing platen 10 and may be rotated by the optical sensor 50 through a known means such as a slip ring It is also possible to transmit the applied power and the signal from the optical sensor 50 to the control circuit in the non-rotating state.

The polishing head 20 receives a rotational driving force from the outside and rotates the wafer W while pressing the wafer W against the polishing pad 11 with the wafer W positioned on the bottom surface. To this end, a pressure chamber is formed inside the polishing head 20, and the pressing force for pressing the wafer W by adjusting the pressure of the pressure chamber can be adjusted.

The conditioner 30 is driven by the rotation of the conditioning disk 31 in a state in which the conditioning disk 31 is pressed against the polishing pad 11 and the surface of the polishing pad 11 Lt; RTI ID = 0.0 > slurry < / RTI >

The slurry supply unit 40 supplies the slurry onto the polishing pad 11 to allow the slurry to flow into the wafer W through the fine grooves formed on the surface of the polishing pad 11. [ Through this, the wafer polishing layer Le is subjected to a chemical polishing process using the slurry.

6 and 7, the optical sensor 50 is fixed to the polishing platen 10 and rotates together with the polishing pad 11, so that the optical sensor 50 can be formed as a circular shape having a predetermined radial distance from the center of the polishing pad 11 (50r) along the path (P). The number of optical sensors 50 provided on the polishing platen 10 may be only one, but a plurality of optical sensors 50 may be provided at different distances from the center of the polishing pad 11, The distribution of the layer Le may be obtained from various paths. In this case, while the optical sensor 50 passes the area under the wafer W, the optical signal Li emitted from the optical sensor 50 receives the light receiving signal Lo reflected on the wafer polishing layer Le .

On the other hand, when the optical sensor 50 is fixed to the lower side of the polishing platen, the optical signal Li is irradiated from the light emitting portion 51 to a position of a predetermined radius of the rotating wafer W, And receives the light receiving signal Lo reflected by the light receiving portion Le at the light receiving portion 52. [ To detect the thickness distribution of the polishing layer of the wafer W, a plurality of optical sensors 50 are arranged in the radial direction from the center of the wafer.

The light receiving signal Lo received by the optical sensor 50 is transmitted to the controller 70 and the controller 70 detects the thickness te and the thickness distribution of the wafer polishing layer from the light receiving signal Lo.

9, the device D arranged on the wafer W is different from the optical signal Li irradiated from the optical sensor 50, which is conventionally formed as very small as about 10 占 퐉 to 20 占 퐉, To the abrasive layer Le with an enlarged spot SP containing at least one of the spots SP. Here, the device D refers to a unit mounted on the wafer W to be manufactured as a semiconductor element or a package. Therefore, a structure for exerting a function is formed on the surface of the device D through a process for manufacturing a semiconductor package, thereby forming a surface having the projections and depressions 99.

Here, the diameter ds of the spot SP from the optical sensor 50 is formed to be larger than at least one of the width Wd and the length Ld of the device D. [ Preferably, the spot SP of the optical sensor 50 is sized to accommodate one device D therein.

As described above, the spot SP of the optical signal Li from the optical sensor 50 is further enlarged compared to the area Wd * Ld of the device D, and the spot SP of the optical sensor 50 (For example, a circular shape having a diameter of 1 inch or more or a rectangular shape having a diagonal length of 1 inch or more) so that the whole device D can be positioned within the wafer polishing layer Le A light receiving signal reflected by the area in which the device D is located is constantly contained in the light receiving signal Lo. Accordingly, even if a part of the optical signal Li is lost or diffused in the area where the device D is located and is not received as the light receiving signal Lo to the optical sensor, The amount of the signal which is lost or diffused in the signal Lo is not uniformed.

11, the reflected light Lo1 reflected by the surface Se of the polishing layer Le and the reflected light Lo1 reflected by the polishing layer Le The thickness of the polishing layer can be precisely detected from the light receiving signal Lo composed of the reflected light Lo2 reflected from the inner boundary Si of the wafer W.

On the other hand, when the spot SP of the optical signal Li emitted from the optical sensor 50 is circular as shown in FIG. 10A, (B) may vary somewhat. Although the thickness of the abrasive layer can be accurately detected even when the inclusion width of the sidewall B formed between the devices D is slightly changed according to the position of the spot SP, By forming in a rectangular or the like shape similar to the shape of the device D, the polishing layer thickness can be detected more accurately.

Here, a similar shape means a shape of a parallelogram, or a shape of both sides (left and right sides or upper and lower sides) is formed into a curved surface in consideration of the locus of movement of the optical signal Li with respect to the plate surface of the wafer.

10B, the width dw of the spot SP 'of the optical signal Li is set so that the width Wd of the device D and the width Wb of the sidewall B become And the length dl of the spot SP 'of the optical signal Li may be determined to be the sum of the length Ld of the device D and the length of the sate region Lb. In this case, at least one device D (including the cleaved part) and one short edge part (B, left and right sides of the device D) Up and down) are simultaneously placed inside the spot SP '.

The width dw of the spot SP 'of the optical signal Li irradiated from the optical sensor 50 is set to be equal to the width Wd of the device D and the width Wb of the sidewall B And the length dl of the spot SP 'of the optical signal Li is an integral multiple of the sum of the length Ld of the device D and the length Lb of the sidewall B, It can be set to double.

In this way, the spot SP 'of the optical signal Li emitted from the optical sensor 50 is formed in a rectangular shape or a parallelogram shape similar to the device shape, or a shape formed of two opposite curved surfaces, , The spot SP 'irradiated from the optical sensor 50 is either lost or diffused in the region where the device D is formed including the predetermined number of devices D and the sate region B Since the amount of the light receiving signal is always kept constant, the effect of obtaining the thickness of the wafer polishing layer more accurately can be obtained.

The control unit 70 receives the light receiving signal Lo received by the optical sensor 50 after being irradiated onto the wafer polishing layer Le with the enlarged spots SP and SP ' The value of the light receiving signal Lo is averaged to sense the thickness of the polishing layer Le. Here, the averaging is not limited to the arithmetic averaging of a plurality of light reception data corresponding to the positions of the spots SP and SP ', and may be a geometric mean or an arithmetic mean or a geometric mean of a value excluding a part of the maximum value and the minimum value And all known methods of extracting the concept of the mean by statistical methods.

The chemical mechanical polishing apparatus according to an embodiment of the present invention configured as described above is configured to cause the optical signal Li to be incident on the polishing layer Le of the wafer W and to receive the light receiving signal Lo reflected from the wafer W The magnitude of the light spots SP and SP 'of the receiving optical sensor 50 is enlarged to be larger than the size of the device so that the light receiving signal Lo reflected by the wafer polishing layer Le is reflected Receiving signal Lo regardless of the irradiation position of the optical signal Li even if a part of the optical signal is lost or diffused in the area where the device is located and is not received by the optical sensor 50. [ The amount of signals that are lost or diffused is not uniform and the measured value differs depending on the position of the light irradiated to the polishing layer Le in order to measure the thickness te of the wafer polishing layer during the chemical mechanical polishing process It is possible to obtain a favorable effect of accurately detecting the thickness of the polishing layer Le from the light receiving signal Lo reflected and incident on the polishing layer at an enlarged area.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the invention.

DESCRIPTION OF REFERENCE NUMERALS
10: polishing pad 11: polishing pad
20: polishing head 30: conditioner
40: Slurry supply part 50: Light sensor
70: Control unit SP, SP ': Spot
W: wafer Le: polishing layer
D: Device B:
Li: optical signal Lo: receiving signal

Claims

A chemical mechanical polishing apparatus for polishing an abrasive layer of a wafer,
An abrasive platen on which an abrasive pad on which the abrasive layer of the wafer comes into contact is rotated and rotated;
Wherein the wafer is rotated while being pressed while the wafer is positioned at a lower position during a chemical mechanical polishing process, and reciprocating in a direction having a radial component of the polishing platen, wherein the reciprocating path includes a first axis direction and a second axis direction At least two axially reciprocating polishing heads comprising:
Wherein the polishing pad is a polishing pad.

The method according to claim 1,
Wherein an angle between the first axial direction and the second axial direction is greater than 0 degrees and less than 90 degrees.

The method according to claim 1,
The polishing head reciprocates in the first axis direction and changes the reciprocating path until it reaches the second axis direction while increasing the inclination angle with respect to the first axis direction by a predetermined angle with respect to the first axis direction And when the polishing head reciprocates in the second axis direction, the polishing head reciprocates while changing the reciprocating path while reducing the inclination angle with respect to the second axis direction by a predetermined angle. Device.

The method according to claim 1,
Wherein the length of the reciprocating stroke is determined to be longer as the polishing head reciprocates in a path having a larger inclination angle with respect to the radial direction of the polishing pad.

5. The method according to any one of claims 1 to 4,
Wherein the polishing pad is provided with a slurry supply groove having a circumferential component.

A chemical mechanical polishing apparatus for polishing an abrasive layer of a wafer,
Wherein a polishing pad to which the polishing layer of the wafer is attached is coated on an upper surface and rotated, and reciprocated by a predetermined stroke during a chemical mechanical polishing process, wherein the reciprocating path includes a third axis direction and a fourth axis direction which are different from each other A polishing platen reciprocating in at least two axial directions;
A polishing head for pressing and rotating the wafer while the wafer is positioned on the lower side during a chemical mechanical polishing process;
Wherein the polishing pad is a polishing pad.

The method according to claim 6,
Wherein the angle between the third axis direction and the fourth axis direction is greater than 0 degrees and less than 90 degrees.

The method according to claim 6,
The polishing platen reciprocates in the third axis direction and changes the reciprocating path until it reaches the fourth axis direction while increasing the tilt angle with respect to the third axis direction by an angle determined with respect to the third axis direction And when the polishing platen reciprocates in the fourth axis direction, the polishing surface is reciprocated while changing the reciprocating path while reducing the inclination angle with respect to the fourth axis direction by a predetermined angle again. Device.

9. The method according to any one of claims 6 to 8,
Wherein the polishing pad is provided with a slurry supply groove having a circumferential component.

10. The method of claim 9,
Characterized in that the polishing head reciprocates in a direction having a radial component of the polishing platen, and the reciprocating path reciprocates in at least two axial directions including a first axis direction and a second axis direction, A chemical mechanical polishing apparatus.

11. The method of claim 10,
Wherein an angle between the first axial direction and the second axial direction is greater than 0 degrees and less than 90 degrees.

11. The method of claim 10,
The polishing head reciprocates in the first axis direction and changes the reciprocating path until it reaches the second axis direction while increasing the inclination angle with respect to the first axis direction by a predetermined angle with respect to the first axis direction And when the polishing head reciprocates in the second axis direction, the polishing head reciprocates while changing the reciprocating path while reducing the inclination angle with respect to the second axis direction by a predetermined angle. Device.

11. The method of claim 10,
Wherein the length of the reciprocating stroke is determined to be longer as the polishing head reciprocates in a path having a larger inclination angle with respect to the radial direction of the polishing pad.