KR20070105616A - Apparatus for mesuring the pad surface profile, and method of revising the pad surface profile taking use of it, and chemical mechanical polishing equipment taking use of it - Google Patents

Abstract

An apparatus for measuring a pad surface profile, a method of revising the pad surface profile using the same, and a chemical mechanical polishing device using the same are provided to make the thickness of a polishing pad uniform by correcting the pad surface profile and thus to improve evenness in chemical mechanical polishing. An apparatus for measuring a pad surface profile includes a body(20), a transfer guide(21), a belt driving gear, a belt, a driving motor, an LM guide, a sensor jig part(28), and a controller. The transfer guide(21) is attached to a first side of the body(20) such that the transfer guide(21) rotates about a central axis. The belt driving gear is installed at two sides of the transfer guide(21). The belt is coupled to the belt driving gear. The driving motor drives the belt driving gear according to the driving signal of the controller. The LM guide is installed in the transfer guide(21). The sensor jig part is equipped with a displacement measuring sensor in its lower portion. The sensor jig part is coupled to the LM guide and the belt so as to move right and left as the belt is driven.

Description

Apparatus for measuring the shape of the polishing pad, a method for correcting the shape of the polishing pad using the same, and a chemical mechanical polishing device using the same EQUIPMENT TAKING USE OF IT}

1 is a schematic diagram of a conventional CMP apparatus;

2 is a schematic diagram of a CMP apparatus including a conventional conditioning mechanism.

3A and 3B are photographs showing the type of conditioning disk head.

4 is a conceptual diagram of a CMP apparatus including a pad shape measuring apparatus capable of measuring a thickness of a pad after conditioning in a CMP process according to a preferred embodiment of the present invention.

Fig. 5 is a plan view showing a polishing pad shape measuring device according to a preferred embodiment of the present invention.

Fig. 6 is a side view showing the polishing pad shape measuring device according to the preferred embodiment of the present invention.

7 is a conceptual diagram of a signal processing method of an apparatus for measuring a polishing pad shape according to a preferred embodiment of the present invention.

8 is a polishing pad profile according to the radial position of the polishing pad measuring the polishing pad shape after conditioning.

Fig. 9 is a sectional view of the approximate polishing pad shape when the shape of the polishing pad is not flat;

10 is a simulation result display screen showing the polishing pad wear rate according to the rotational ratio of the conditioner to the rotation speed of the polishing pad.

<Explanation of symbols for main parts of the drawings>

11: polishing table 12: polishing pad

13: slurry 14: wafer

15: Grinding Head 16: Diamond Conditioner

17: conditioner disk 18: wafer outer diameter size

19: conditioner outer diameter size

20: body of the polishing pad shape measuring device

21: Feed guide 22: Center axis

23: drive motor 25: belt drive gear

26: belt 27: LM guide

28: sensor jig part (guide block) 30: displacement measuring sensor

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a chemical mechanical polishing (CMP) process technology applied in a semiconductor device fabrication process. The polishing pad profile (exactly, ' Depth '), a method for correcting a polishing pad shape using the same, and a chemical mechanical polishing apparatus using the same.

The CMP process technology improves operating characteristics by separating nano-sized devices on a silicon substrate for high integration and high performance of the semiconductor manufacturing process, and forms wirings of semiconductor chips having a multilayered structure. It is used as a process to insulate it. Separation and multi-layer wiring of the device is performed after the gap fill process of pattern irregularities such as planarization and deposition of topography according to the surface element formation of CMP technology. This is accomplished by uniformly removing residual material over the entire wafer surface.

  1 is a schematic view showing one example of a conventional chemical mechanical polishing apparatus.

  Referring to FIG. 1, in the chemical mechanical polishing process, a polishing head 15 of a carrier on which a wafer 14 is attached is pressed to a plate 11 on which a pad is mounted. In the intervening state of the slurry 13 containing the reactive chemical liquid and the abrasive particles, the polishing pad 12 and the wafer 14 cause relative movement to remove irregularities on the wafer surface.

In this process, the CMP process requires fast polishing speed to improve processing efficiency, polishing uniformity on the entire surface of the wafer, and flatness in die corresponding to chip size, and abrasive reproducibility. Factors influencing these CMP results include device press accuracy, pressurization method, contact trajectory between wafer and pad, abrasive grain type, size, concentration, oxidizer and complexing agent in the slurry. Agents, pH, corrosion inhibitors, process temperature, and uniformity of the patterns formed on the wafer surface are all factors. In particular, in the case of the polishing pad 12, which is a polyurethane foam that is in direct contact with the wafer 14 to be in relative motion, the uniform distribution of surface roughness on the polishing pad, the surface formed inside the pad and the micro The removal of pores of abrasive residues, the uniformity of the thickness of the pads, and the like act as important factors.

The foamed polyurethane polishing pad 12 used in the CMP process is characterized by a reduction in surface roughness of the polishing pad surface after the polishing process and glazing of pores formed on the pad surface by polishing residues. This phenomenon occurs in addition to the reduction of the removal rate due to the reduction of the surface roughness, the abrasive particles and the chemical liquid contained in the slurry can not be uniformly supplied to the pattern portion distributed over the entire surface of the wafer, thereby reducing the polishing uniformity Will result.

2 is a schematic view showing an example of a polishing apparatus equipped with a conditioning head.

Referring to FIG. 2, in order to solve this problem of the CMP process, the surface roughness is increased by scraping the pad surface using a conditioner in which diamond grains are electrodeposited in the same kinematic behavior as the polishing method. Conditioning and opening pores are needed in addition to the CMP process.

3A and 3B are photographs showing the type of conditioning disk head. Figure 3a is a solid type conditioner, Figure 3b shows a hollow type conditioner. 3A and 3B are top views of the conditioning disc head, and top views of FIGS. 3A and 3B show regions of diamond particles in contact with the pad when the following conditioning disc heads are used. That is, when the solid type conditoner of FIG. 3A is used, the entire inside of the circle is in contact with the pad and is conditioned. When the Hollow type conditioner of FIG. 3B is used, the pad is contacted with the pad and is conditioned. The conditioning disk head of FIG. 2 shows the case where the Hollow type conditioner of FIG. 3B is used.

The conditioning process has the advantage of increasing the surface roughness of the polishing pad surface and opening up the pores, but it causes the wear of the polishing pad to shorten its lifespan, and eventually the life of the polishing pad is dominant in the degree of conditioning. In addition, the polishing process causes wear of the polishing pad to cause a change in the shape of the polishing pad at the contact portion on the polishing pad that the wafer contacts during the CMP process (see FIGS. 8 and 9), which leads to a change in the polishing uniformity during the actual CMP process. There is a problem that will lead to deterioration.

Therefore, in order to maintain the polishing uniformity in the CMP process, it will be said that uniformity of the polishing surface is required during the conditioning process.

Conventionally, the pressure, speed, and oscillation conditions of the conditioning mechanism are changed for uniform conditioning of the pad surface, and the optimum conditions are selected and reflected in the CMP process based on the results obtained by performing the CMP under the corresponding conditions. However, this has the disadvantage that the cost of using a dummy wafer (dummy), the process development time is increased, and stable and continuous polishing pad management is difficult.

The present invention has been made to solve the above problems,

SUMMARY OF THE INVENTION An object of the present invention is to provide an apparatus for measuring such a change in shape of a polishing pad as the thickness change occurring in the radial direction of the polishing pad appearing after the pad conditioning process in the CMP process affects the polishing uniformity of the wafer during CMP.

Another object of the present invention is to provide a method for correcting the shape of a polishing pad by using the polishing pad shape measuring device.

Still another object of the present invention is to provide a CMP apparatus which can improve polishing uniformity during the CMP process by securing a uniform and flat polishing pad thickness through the polishing pad shape measuring device and the polishing pad shape correction method.

In order to achieve the above object, the polishing pad profile measuring device for measuring the shape of the polishing pad after conditioning of the present invention is

Body Part,

A transport guide attached to one side of the body and rotatable based on a central axis;

A belt drive gear installed at both sides of the transfer guide,

A belt coupled to the belt drive gear,

A drive motor for driving the belt drive gear in accordance with a drive signal from a controller, an LM guide installed in the transfer guide,

A sensor jig unit attached to a lower portion of the displacement measuring sensor and coupled to the LM guide and attached to the belt and movable left and right along the LM guide by driving of a belt, and

It includes a control unit for controlling the driving of the drive motor, the rotation of the transfer guide and the device as a whole.

Preferably, the drive motor is a stepping drive motor capable of feeding speed and position control.

Preferably, the displacement measuring sensor is a non-contact laser displacement sensor or a contact linear gauge.

The shape correction method of the polishing pad after conditioning of the present invention

Measuring the profile of the polishing pad using a displacement measuring sensor,

Based on the measured value in the above step, the controller determines whether the difference between the maximum value and the minimum value of the wear amount of the portion of the polishing pad contacted by the wafer, or whether the slope is greater than or equal to the set value, and if the value is equal to or greater than the set value, sends a command signal Adjusting the rotational speed of the conditioner, and

Conditioning the polishing pad for a set time, in accordance with the rotational speed of the adjusted conditioner.

Preferably, after the conditioning step according to the adjusted number of revolutions of the conditioner, the shape of the polishing pad is re-measured using a displacement measuring sensor, and the difference between the maximum value and the minimum value of the wear amount of the portion of the polishing pad to which the wafer contacts, or If the slope is lower than the set value, the CMP process proceeds.

Preferably, in the measuring and re-measuring step of the polishing pad shape, instead of measuring the entire diameter of the polishing pad, only the polishing pad shape of the polishing pad radius from the polishing pad center to the polishing pad edge is measured.

In some cases, in the rotation speed adjustment step of the conditioner, not only the rotation speed of the conditioner but also the rotation speed of the polishing pad can be adjusted.

Hereinafter, with reference to the drawings, the present invention will be described in more detail.

4 is a conceptual diagram of a CMP apparatus including a pad shape measuring apparatus capable of measuring a thickness of a pad after conditioning in a CMP process according to a preferred embodiment of the present invention.

Referring to FIG. 4, in consideration of the conditioner outer diameter size 19 positioned on the polishing pad after conditioning, the thickness of the polishing pad 12 may be measured using the displacement measuring sensor 30 of FIG. 6. The displacement measuring sensor is attached to the lower portion of the sensor jig portion 28 so as to measure the thickness of the polishing pad 12. The polishing pad profile (thickness) due to the wear of the polishing pad after conditioning has the same shape in the circumferential direction of the polishing pad. This is because the polishing pad also rotates at a constant speed during the rotation of the conditioner. Therefore, the sensor jig part 28 measures the thickness of the polishing pad by the displacement measuring sensor while transferring from the point A (polishing pad center) to the point B (polishing pad edge) along the transfer guide 21.

The sensor jig part 28 to which the displacement measuring sensor is attached is driven by the stepping drive motor 23 capable of controlling the feed speed and the position.

Fig. 5 is a plan view showing a polishing pad shape measuring device according to a preferred embodiment of the present invention, and Fig. 6 is a side view showing the polishing pad shape measuring device according to a preferred embodiment of the present invention.

5 and 6, belt drive gears 25 are formed on both sides of the transfer guide 21, and drive motors 23 are formed on one side thereof. The belt 26 is wound around the belt drive gear 25, and the sensor jig part 28 is attached to the belt 26. Meanwhile, the LM guide 27 is formed in the transfer guide 21, and the sensor jig part 28 is installed to move along the LM guide 27. In other words, the sensor jig portion 28 serves as a guide block. The displacement measuring sensor 30 is indicated by a dotted line because it is provided below the sensor jig part 28.

The driving of the sensor jig part 28 is made by the driving of the drive motor 23. First, the drive motor 23 is driven by receiving an operation command from the PC control unit. Accordingly, the left belt drive gear 25 coupled thereto rotates, and the belt 26 geared with the belt drive gear 25 operates. At this time, the sensor jig portion 28 coupled to the LM guide 27 moves the designated AB section on the polishing pad together with the driving of the belt 26, and thus the measurement jig portion 28 The thickness will be measured.

 Here, the displacement measuring sensor 30 may be a non-contact sensor or a contact sensor in consideration of the type of the pad and the surrounding situation in the CMP process, a non-contact laser displacement sensor or a linear gauge may be used in contact. .

After measuring the thickness of the polishing pad, the feed guide 21 is rotated at a predetermined angle with respect to the central axis to avoid interference with the device during CMP.

The measurement signal value is displayed by the displacement measuring sensor 30 to show the thickness shape in the PC through a signal processing process.

7 is a conceptual diagram of a signal processing method of an apparatus for measuring an abrasive polishing pad shape according to an embodiment of the present invention. That is, Fig. 7 shows signal processing for measuring the shape change of the polishing pad, and the data measured using the measurement displacement sensor is A / D converted and displayed on the computer screen. The measured thickness of the polishing pad affects the polishing uniformity of the wafer during the CMP process.

8 is a polishing pad profile according to the radial position of the polishing pad measuring the pad shape after conditioning, according to an embodiment of the present invention.

A segment type conditioner was fixed in the circumferential direction of the conditioner disk, and when the conditioner and the pad were relatively moved at the same rotational speed under constant conditioning pressure, the pad shape change after 1 hour conditioning and 2 hours conditioning was measured. 8 is a display screen displaying a result of measuring a profile of a polishing pad.

Referring to FIG. 8, the profile of the polishing pad after 1 hour conditioning is approximately horizontal, but the shape of the polishing pad 2 hours is slightly inclined downward toward the center of the polishing pad, that is, a flat shape. It can be seen that it does not hold.

9 is a cross-sectional view of an approximate polishing pad shape when the polishing pad is not flat. That is, it is sectional drawing which shows the approximate abrasive pad shape after 2 hours conditioning in the said experiment. In this state, if the CMP process of the wafer is continued continuously, the polishing uniformity of the wafer during the CMP process is significantly reduced. Therefore, in this case, it is required to make the polishing pad shape flat.

In the system of the present invention, when the depth difference of the portion where the wafer is placed becomes larger than the set value, the PC controller determines this and issues an alarm or command to change the conditioning rotation condition. In the case of manual operation, the device driving personnel change the conditioning rotation speed. In the case of automatic operation, the rotation speed of the conditioner is changed by the command signal of the PC controller. The set value may be changed according to the needs of the user, but approximately 10 μm may be used.

That is, in order to compensate the polishing pad shape when the difference between the maximum value and the minimum value of the wear amount of the portion of the CMP where the wafer contacts (in the conditioned area) or the slope of the measured polishing pad shape is greater than or equal to the set value, It will change the rotation speed.

In this way, by varying the number of conditioning rotations based on the measured polishing pad profile results, it is possible to reduce excessive wear of the polishing pad at the place where the conditioner outer circumference near the pad center passes, and to improve the polishing uniformity of the wafer during the CMP process. The flatness of the polishing pad can be kept constant.

In general, when the conditioner is equipped with a diamond conditioner with a constant width in the outer circumferential direction of the conditioner disc, the condition is defined as the rotation speed Wc of the conditioner and the rotation speed Wp of the polishing pad, and the ratio R = Wc / Wp is adjusted. In the case of conditioning, the simulation results for the polishing pad wear rate are shown in FIG. 10.

10 is a simulation result display screen showing the polishing pad wear rate according to the rotational ratio of the conditioner to the rotation speed of the polishing pad.

Referring to FIG. 10, when the rotational speed of the conditioner is faster than the polishing pad rotational speed, that is, when R> 1 (eg, R = 1.5), the wear state of the polishing pad may be larger than the polishing pad center portion. It is relatively small at the pad edge portion.

This condition occurs even when the conditioner and the polishing pad have the same rotation speed, that is, when R = 1.0, but when the conditioner's rotation speed is smaller than the polishing pad's rotation, that is, when R <1 as the R value decreases, The wear state of the polishing pad is reduced at the center portion of the pad, and on the contrary, the wear state is increased at the outer peripheral side (edge portion) of the polishing pad.

In the present invention, after measuring the polishing pad shape through the measurement step of the polishing pad shape, the PC control unit determines whether the difference between the maximum value and the minimum value of the wear amount of the portion of the polishing pad contacted by the wafer, or whether the inclination is more than the set value. If it is determined and the value is more than the set value, a command signal is sent to adjust the rotation speed of the conditioner. That is, R (Wc / Wp), which is the ratio of the conditioner rotational speed Wc to the polishing pad rotational speed Wp, is adjusted to correct the worn shape of the conditioner.

In general, based on the results shown in FIG. 10, it is preferable to maintain conditioning with an R value of 1 or less in order to keep the shape of the polishing pad uniform.

The apparatus capable of measuring the shape of the polishing pad configured in the CMP apparatus of the present invention can determine the nonuniformity of the wear state across the entire surface of the polishing pad after conditioning, and again change the mechanical conditions of the conditioning based on the measurement result. By applying to the conditioning process, the shape of the polishing pad can be corrected.

Through this correction process, it is possible to secure the uniformity of the wafer while repeating during the CMP process, and the effective life of the polishing pad can also extend the life of the pad. In addition, it is possible to pursue a stable CMP process by controlling the shape of the polishing pad from the stabilization process of attaching the polishing pad to the surface plate and performing initial conditioning, and has the advantage of being used as an objective criterion for determining the life of the polishing pad.

Claims (20)

In the apparatus for measuring the shape of the polishing pad after conditioning, Body 20, A transfer guide 21 attached to one side of the body and rotatable based on a central axis; Belt drive gear 25 is provided on both sides of the transfer guide, A belt 26 coupled to the belt drive gear, A drive motor 23 for driving the belt drive gear in accordance with a drive signal from a controller; An LM guide 27 installed in the transfer guide; A sensor jig part 28 attached to a lower portion of the displacement measuring sensor 30, coupled to the LM guide 27, attached to the belt 26, and movable left and right along the LM guide by driving of the belt, and And a control unit which controls the driving of the drive motor, the rotation of the conveyance guide and the apparatus as a whole. The method of claim 1, The drive motor is a polishing pad shape measuring apparatus, characterized in that the stepping drive motor capable of controlling the feed rate and position. The method of claim 1, And the displacement measuring sensor is a contact sensor or a non-contact sensor. The method of claim 3, wherein And the displacement measuring sensor is a non-contact laser displacement sensor or a contact linear gauge. In the method of correcting the shape of the polishing pad after conditioning, Measuring the profile of the polishing pad using a displacement measuring sensor, Based on the measured value in the above step, the controller determines whether the difference between the maximum value and the minimum value of the wear amount of the portion of the polishing pad contacted by the wafer, or whether the slope is greater than or equal to the set value, and if the value is equal to or greater than the set value, sends a command signal Adjusting the rotational speed of the conditioner, and Conditioning the polishing pad for a set time, according to the rotation speed of the adjusted conditioner, Polishing pad shape correction method comprising a. The method of claim 5, After the conditioning step according to the rotation speed of the adjusted conditioner, Re-measure the shape of the polishing pad by using the displacement measuring sensor, and perform the CMP process when the difference between the maximum value and the minimum value of the wear amount of the portion of the polishing pad in contact with the wafer or the slope thereof becomes lower than the set value. Polishing pad shape correction method. The method according to claim 5 or 6, In the measuring and re-measuring step of the polishing pad shape, A method for correcting a polishing pad shape, characterized in that only the polishing pad shape of the polishing pad radius from the center of the polishing pad to the polishing pad edge is measured, not the entire diameter of the polishing pad. The method of claim 5, In the rotation speed adjustment step of the conditioner, A polishing pad shape correction method, characterized in that not only the rotational speed of the conditioner but also the rotational speed of the polishing pad are adjusted. The method of claim 5, And the displacement measuring sensor is a contact sensor or a non-contact sensor. The method of claim 9, And the displacement measuring sensor is a non-contact laser displacement sensor or a contact linear gauge. An apparatus for measuring the shape of a polishing pad after conditioning a polishing pad by a conditioner, wherein the shape of the polishing pad is measured using a displacement measuring sensor (30). In the chemical mechanical polishing apparatus, After conditioning the polishing pad by the conditioner, the profile of the polishing pad is measured using the displacement measuring sensor 30, and based on this, the polishing pad shape is corrected by adjusting the rotation speed of the conditioner. Mechanical polishing device. A chemical mechanical polishing apparatus comprising a conditioner for conditioning a polishing pad, One side of the CMP apparatus is provided with a polishing pad shape measuring device for measuring the profile of the polishing pad after conditioning the polishing pad, The polishing pad shape measuring device Body 20, A transfer guide 21 attached to one side of the body and rotatable based on a central axis; Belt drive gear 25 is provided on both sides of the transfer guide, A belt 26 coupled to the belt drive gear, A drive motor 23 for driving the belt drive gear in accordance with a drive signal from a controller; An LM guide 27 installed in the transfer guide; A sensor jig part 28 attached to a lower portion of the displacement measuring sensor 30, coupled to the LM guide 27, attached to the belt 26, and movable left and right along the LM guide by driving of the belt, and And a control unit for controlling the driving of the drive motor, the rotation of the transfer guide, and the device as a whole. The method of claim 13, The driving motor is a chemical mechanical polishing apparatus, characterized in that the stepping drive motor capable of controlling the feed rate and position. The method of claim 13, And the displacement measuring sensor is a non-contact laser displacement sensor or a contact linear gauge. A chemical mechanical polishing apparatus comprising a conditioner for conditioning a polishing pad, Measuring the profile of the polishing pad using a displacement measuring sensor, Based on the measured value in the above step, the controller determines whether the difference between the maximum value and the minimum value of the wear amount of the portion of the polishing pad contacted by the wafer, or whether the slope is greater than or equal to the set value, and if the value is equal to or greater than the set value, sends a command signal Adjusting the rotational speed of the conditioner, and Conditioning the polishing pad for a set time, in accordance with the rotational speed of the adjusted conditioner, And chemically polish the profile of the polishing pad after conditioning the polishing pad. The method of claim 16, After the conditioning step according to the rotation speed of the adjusted conditioner, Re-measure the shape of the polishing pad by using the displacement measuring sensor, and perform the CMP process when the difference between the maximum value and the minimum value of the wear amount of the portion of the polishing pad in contact with the wafer or the slope thereof becomes lower than the set value. Chemical mechanical polishing device. The method according to claim 16 or 17, In the measuring and re-measuring step of the polishing pad shape, A chemical mechanical polishing apparatus, characterized in that only the polishing pad shape of the polishing pad radius from the polishing pad center to the polishing pad edge is measured, not the entire diameter of the polishing pad. The method of claim 16, In the rotation speed adjustment step of the conditioner, A chemical mechanical polishing apparatus characterized by adjusting not only the rotational speed of a conditioner but also the rotational speed of a polishing pad. The method of claim 16, And the displacement measuring sensor is a non-contact laser displacement sensor or a contact linear gauge.

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