JP2003332281A - Cmp process - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a CMP process suitable for polishing a wafer having a surface profile with a thick edge and a thin middle portion to improve uniformity of flattening. <P>SOLUTION: A first polishing step and a second polishing step are applied to the wafer by using a CMP device. A rotating direction of a polishing disk and a rotating direction of a polishing head are adjusted to finely control a thickness distribution situation of a deposited layer on a surface of the wafer in the first polishing step and to obtain required flatness and height in the second polishing step. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a CMP (Chemical Mechanical Polishing) method and, more particularly, to improving the uniformity of planarization, and to perform overall planarization on a wafer having a surface contour with a thick edge and a thin center. The effect of (Global Planarization) is obtained and is related to the CMP process.

[0002]

2. Description of the Related Art The depth of focus (DOF) in photolithography has been more and more precisely limited as the dimensions of IC devices have been reduced and wiring has become highly integrated and multilayered. For this reason, the planarization technique has become more important. cm
The P process is a planarization method that combines chemical reaction and mechanical polishing, and its purpose is to planarize a dielectric layer or metal layer having irregularities (steps) on a wafer. By the planarization, subsequent thin film deposition, high-precision exposure and control of the etching stop layer are smoothly performed.

FIG. 1 is a diagram showing a polishing apparatus using a conventional CMP system.

In FIG. 1, the polishing apparatus 10 is a polishing platen 1.
2 and a polishing pad 14 attached to the surface of the polishing platen 12.
And the polishing head 1 mounted above the polishing platen 12.
6 is provided.

When performing the CMP process, a predetermined polishing surface of the wafer 18 is pressed against the polishing pad 14 by the polishing head 16 and a rotational force and a pressure P in the A direction are applied to the wafer 18.
On the other hand, the polishing platen 12 also rotates in a predetermined direction B similar to the direction A. Further, the polishing liquid 20 for advancing the CMP process is continuously supplied from the supply system 22 onto the polishing platen 12. As described above, the chemical reaction by the polishing liquid 20 and the mechanical polishing performed on the wafer 18 placed on the polishing platen 12 gradually remove the protrusions on the predetermined surface of the wafer 18 and flatten the wafer.

However, the contour of the irregularities on the predetermined polished surface of the wafer, the change in the short dimension (CD), and the phenomenon that the edge of the wafer is thick and the center is thin (due to an unnecessary pattern formed on the edge of the wafer) As a result, the planarization effect of the CMP process is affected.

In order to improve the flattening effect by the CMP process, conventionally, for example, the pressure on the polishing head, the rotation speed of the polishing head and the polishing platen, the flow rate of the polishing liquid, and the chemical composition of the abrasive grains in the polishing liquid. The method of adjusting process parameters such as the process temperature, the material of the polishing pad and the like has been widely used.

However, since the process parameters correlate with each other, and the correlativity is complicated and depends on the polishing environment, it is difficult to perform a test for determining a direct correlation with the hardware setting of the manufacturing equipment, and the measuring device is also exceptional. It is expensive.

Further, in order to carry out polishing in accordance with various contours having different steps, a multi-type polishing head adapted to the multi-region polishing control was devised, but the new polishing head still could not obtain the desired effect. . Incidentally, in the case of multi-region polishing control, the flatness effect between regions cannot be controlled.

Therefore, conventionally, it has been an important subject to determine a variable that can adjust the process parameter in various polishing apparatuses in the CMP process and has no correlation with the process parameter.

[0011]

SUMMARY OF THE INVENTION In order to solve the above problems, an object of the present invention is mainly suitable for polishing a wafer having a surface contour with a thick edge and a thin center, and is used for planarization. To provide a CMP process that improves the uniformity of the.

[0012]

In order to achieve the above object, in the CMP process of the present invention, the rotation direction of the polishing head is a second rotation direction (the first rotation direction is, for example, the rotation direction of a polishing platen). ) And polishing the wafer, and a second polishing step in which the wafer is polished with the rotation direction of the polishing head being opposite to the second rotation direction.

In the CMP process of the present invention, the first polishing step is a step for finely adjusting the deposition layer thickness distribution pattern on the wafer surface to reduce the difference between the edge thickness and the central thickness. The second polishing step is a step for performing the main CMP process to obtain the required flatness and height.

The CMP apparatus used in the CMP process of the present invention comprises at least one polishing surface plate, a polishing pad adhered to the surface of the polishing surface plate, and at least one polishing head mounted above the polishing surface plate. can do. When polishing a wafer, the rotation direction of the polishing platen is set to the first rotation direction, the predetermined polishing surface of the wafer is pressed onto the polishing pad by the polishing head, and the wafer is rotated.

The second rotation direction may be opposite to the first rotation direction. In this case, in the first polishing step, the rotation direction of the polishing head is opposite to the rotation direction of the polishing platen, the polishing speed of the thick edge portion is fast, and the polishing speed of the thin central portion is slow, but in the second polishing step The rotation direction of the head is the same as the rotation direction of the polishing platen, and the polishing speed at the thick edge portion is slow and that at the thin center portion is fast. The difference between the edge thickness and the central thickness of the wafer determines the polishing time and the rotation speed of the polishing head in the first polishing step, and the required wafer surface thickness is used to polish the second polishing step. The time and rotation speed of the polishing head can be determined.

On the other hand, the first rotation direction may be the same as the second rotation direction. In this case, the rotation direction of the polishing head is the same as the rotation direction of the polishing surface plate in the first polishing step, but the rotation direction of the polishing head is opposite to the rotation direction of the polishing surface plate in the second polishing step. The polishing time and the rotation speed of the polishing head in the first polishing step are determined by the difference between the required wafer surface thickness and the difference between the edge thickness and the central thickness of the wafer. And the thickness of the central portion can determine the polishing time and the rotation speed of the polishing head in the second polishing step.

The first polishing step and the second polishing step may be performed by the same polishing surface plate or different polishing surface plates.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION The structure and operation of an embodiment of the present invention which achieves the above-mentioned object and solves the problems of the prior art will be described in detail with reference to the accompanying drawings.

The CMP process of the present invention is primarily suitable for polishing wafers having a thick edge and thin center surface contour. Here, the surface contour as described above is, for example, the surface contour of the deposition layer formed by the HDPCVD (high density plasma chemical vapor deposition) method.

First Embodiment FIG. 2 is a diagram showing a polishing apparatus according to an embodiment of the present invention.
In FIG. 2, the polishing apparatus 30 includes a polishing platen 32, a polishing pad 34 attached to the surface of the polishing platen 32, and a polishing head 36 mounted above the polishing platen 32.

When the CMP process is performed, a predetermined polishing surface of the wafer 38 is pressed against the polishing pad 34 by the polishing head 36, and a rotational force and a pressure P in the A direction are applied to the wafer 38.
On the other hand, the polishing platen 32 also rotates in the predetermined direction B.
Further, the polishing liquid 40 for advancing the CMP process is continuously supplied from the supply system 42 onto the polishing platen 32. As described above, the chemical reaction by the polishing liquid 40 and the mechanical polishing performed on the wafer 38 placed on the polishing platen 32 gradually remove the protrusions on the predetermined surface of the wafer 38.

The CMP process of the first embodiment of the present invention comprises two stages.

First, the first polishing step is performed. That is, the rotation direction A of the polishing head is set to the opposite direction to the rotation direction B of the polishing platen 32 to polish the wafer 38 (see FIG. 2A). As a result, the polishing rate at the thick edge portion is high and the polishing rate at the thin central portion is low. Here, the polishing time and the rotation speed of the polishing head 36 are appropriately adjusted according to the difference between the edge thickness and the central thickness. As a result, the thickness distribution mode of the deposited layer on the wafer surface is finely adjusted, and the difference between the edge thickness and the central thickness (hereinafter referred to as the difference in thickness) is reduced.

Next, the wafer 38 placed on the polishing platen 32.
Is subjected to a second polishing step. That is, polishing is performed with the rotation direction A of the polishing head 36 and the rotation direction B of the polishing platen 32 being the same direction (see FIG. 2B). As a result, the polishing rate at the thick edge portion becomes slower and the polishing rate at the thin central portion becomes faster. Here, the polishing time and the rotation speed of the polishing head 36 are appropriately adjusted according to the required wafer surface thickness (thickness to be left on the wafer surface). The result is the required flatness and altitude.

Second Embodiment The CMP process of the second embodiment of the present invention consists of two stages.

First, the first polishing step is performed. That is, the wafer 38 is polished with the rotation direction A of the polishing head and the rotation direction B of the polishing platen 32 being the same (see FIG. 2B). Here, the polishing time and the rotation speed of the polishing head 36 are determined by the difference between the required wafer surface thickness and the above-mentioned difference between the portions.

Next, a second polishing step for further polishing the wafer placed on the polishing platen 32 is performed. That is, polishing is performed with the rotation direction A of the polishing head being opposite to the rotation direction B of the polishing platen 32 (see FIG. 2A). Here, the polishing time and the rotation speed of the polishing head 36 are determined by the difference in the inter-part thickness. The result is the required flatness and altitude.

Third Embodiment In the first embodiment described above, the two polishing steps are performed on the same polishing platen, but in this embodiment, the two polishing steps in the first embodiment are different polishing steps. It is performed on a plate (two polishing plates).

FIG. 3 is a plan view showing a CMP system device according to the present invention.

The CMP system device 50 includes a plurality of polishing tool sets 52 (52-1 to 52-3), a wafer transfer tool set 54, a wafer mounting tool set 56, and a wafer unloading tool set 5.
It consists of 4. Each polishing tool set 52-1 to 52-3 is
Each of the polishing surface plates 3 is similar to the polishing device 30 described above.
2, a polishing pad 34, a polishing head 36, and a polishing liquid 40.

Which polishing step each polishing tool set 52-1 to 52-3 is applied to is determined by the setting program of the CMP system. For example, in the first polishing step, the first polishing tool set 52-1 is used and the polishing head 36
The direction A of rotation of the polishing table 32 is opposite to the direction B of rotation of the polishing platen 32,
The polishing time and the rotation speed of the polishing head 36 are appropriately adjusted by the difference in the thickness between the portions. Usually, the polishing time in this case is relatively short. On the other hand, in the second polishing step, the second polishing tool set 52-2 or the third polishing tool set 52-
3, the rotation direction A of the polishing head and the rotation direction B of the polishing platen 32 are set to the same direction, and the polishing time and the rotation speed of the polishing head 36 are set so that the required flatness and altitude can be obtained. Adjust according to the thickness. Usually, the polishing time in this case is relatively long.

According to the CMP process of the third embodiment of the present invention, first, the first wafer 38-1 is transferred to the first polishing tool set 52-1 and the first polishing step having a short time is performed. . That is, the rotation direction A of the polishing head 36 is set to the polishing surface plate 32.
Polish in the direction opposite to the direction B of rotation. Here, the thickness distribution mode of the deposited layer on the surface of the wafer 38-1 is finely adjusted to reduce the difference in the inter-part thickness.

Next, the first wafer 38-1 is transferred to the second polishing tool set 52-2, and the second polishing step for a long time is performed. That is, polishing is performed with the rotation direction A of the polishing head 36 and the rotation direction B of the polishing platen 32 being the same direction. The result is the required flatness and altitude.

The second polishing step is performed on the first wafer 38-1, and at the same time, the second wafer 38-2 is transferred to the first polishing tool set 52-1 to perform the first polishing step. You can go. Then, as soon as the second polishing step for the first wafer 38-1 is completed, the second wafer 38-2 is transferred to the second polishing tool set 52-2 and the second polishing step is performed.

As described above, since different polishing steps are performed on the same wafer by different polishing surface plates 32, polishing efficiency and throughput in the entire CMP process are improved.
Incidentally, since the polishing head 36 of each polishing tool set does not need to change its rotating direction A periodically, it has a long service life.

The two polishing steps in the second embodiment may be performed by two polishing surface plates, respectively. In this case, for example, the second polishing tool set 52-2 is used in the first polishing step, and the first or third polishing tool set 52-1 or 52-3 is used in the second polishing step, Change the setting program of the CMP system.

Then, in the first polishing step using the second polishing tool set 52-2, the rotation direction A of the polishing head 36 and the rotation direction B of the polishing platen 32 are set to the same direction, and the polishing time and the polishing head 36 are set. Of the wafer is determined by the difference between the required wafer surface thickness and the difference in the thickness between the portions.

In the second polishing step using the first or third polishing tool set 52-1 or 52-3, the rotation direction A of the polishing head 36 is set to the opposite direction of the rotation direction B of the polishing platen 32, and The polishing time and the rotation speed of the polishing head 36 are determined by the difference in the inter-part thickness so that the flatness and the height can be obtained.

Although the present invention has been presented as the above embodiment, this is not intended to limit the present invention, and those skilled in the art can make variations and modifications within the spirit and scope of the present invention. Therefore, the scope of rights of the present invention shall be subject to the claims.

[0040]

As described above, when the CMP process of the present invention is used to polish a wafer having a surface contour with a thick edge portion and a thin center portion, the effect of global planarization is obtained, and planarization is performed. Uniformity is improved.

[Brief description of drawings]

FIG. 1 is a diagram showing a polishing apparatus using a conventional CMP process.

2A and 2B are views showing a polishing apparatus according to an embodiment of the present invention, in which FIG. It is a figure which shows the case where it is the same.

FIG. 3 is a plan view showing a CMP system device according to the present invention.

[Explanation of symbols]

10, 30 Polishing device 12, 32 Polishing surface plate 14, 34 Polishing pad 16,36 Polishing head 18,318 wafers 20, 40 polishing liquid 22 Supply system 50 CMP system equipment 52 Polishing tool set 54 Wafer transfer tool set 56 Wafer attachment set 58 Wafer wholesaler set

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor, Mr. Kanou             Taiwan Hsinchu County, Dongdong Town, Jinfu Street, No. 6, No. 19 F term (reference) 3C058 AA07 AA11 AB01 CA01 CB01                       DA12

Claims (9)

[Claims] 1. A CM comprising at least one polishing surface plate, a polishing pad adhered to the surface of the polishing surface plate, and at least one polishing head mounted above the polishing surface plate.
The wafer is rotated so that the rotation direction of the polishing platen is set to the first rotation direction and the predetermined polishing surface of the wafer is pressed onto the polishing pad by the polishing head and the wafer is rotated. In the CMP process for polishing, a first polishing step of polishing the wafer with the rotation direction of the polishing head being a second rotation direction, and the rotation direction of the polishing head being opposite to the second rotation direction. And a second polishing step for polishing the wafer in a direction. 2. The C according to claim 1, wherein the second rotation direction is opposite to the first rotation direction.
MP process. 3. The polishing time in the first polishing step and the rotation speed of the polishing head are determined by the difference between the edge thickness and the central thickness of the wafer.
The CMP process described in. 4. The CMP according to claim 2, wherein the required wafer surface thickness determines the polishing time and the rotation speed of the polishing head in the second polishing step.
process. 5. The CM according to claim 1, wherein the first rotation direction and the second rotation direction are the same.
P process. 6. The polishing time in the first polishing step and the rotation speed of the polishing head are determined by the difference between the required wafer surface thickness and the difference between the edge thickness and the central thickness of the wafer. The CMP process of claim 5 characterized. 7. The polishing time and the rotation speed of the polishing head in the second polishing step are determined by the difference between the edge thickness and the central thickness of the wafer. CMP process. 8. The first polishing step and the second polishing step are performed on the same polishing platen.
8. A CMP process according to any one of claims 7 to 7. 9. The CMP process according to claim 1, wherein the first polishing step and the second polishing step are performed by different polishing platens.