US20020102917A1

US20020102917A1 - Polishing method using dynamic feedback recipe

Info

Publication number: US20020102917A1
Application number: US09/922,311
Authority: US
Inventors: Chih-Hung Lee; Chi-Yeh Huang; Chi-Hung Lee; Kuo-Ju Liu; Liang-Kuei Chou
Original assignee: Winbond Electronics Corp
Current assignee: Winbond Electronics Corp
Priority date: 2001-01-30
Filing date: 2001-07-21
Publication date: 2002-08-01

Abstract

A polishing method using a dynamic feedback recipe is disclosed. The polishing method includes steps of providing a first recipe, polishing a first wafer according to the first recipe, measuring the first wafer to obtain a first determined data from the first wafer, calculating a second recipe according to a specific equation and the first determined data, and replacing the first recipe with the second recipe and polishing a second wafer according to the second recipe.

Description

FIELD OF THE INVENTION

The present invention relates to a polishing method using a dynamic feedback recipe, and more particularly to a chemical mechanical polishing method using a dynamic feedback recipe.

BACKGROUND OF THE INVENTION

FIG. 1 is a cutaway view illustrating polishing apparatus according to the prior art. A

wafer

10 is polished by a chemical mechanical polishing apparatus including a carrier 12 and a carrier film 14. Generally, because the polishing rates are different in the center and the edge of the wafer 10, a back side pressure 11 is applied in the wafer 10 to change the central polishing rate of the wafer 10 for approaching a consist polishing rate for the whole wafer 10 and achieving a preferred non-uniformity.

For maintaining the non-uniformity of the

wafer

10 in a specification limit, the methods for using the back side pressure 11 or the carrier 12 oscillation can reduce the difference between the central and the edge of the polishing rate. However, along with consuming and deforming of a polishing pad 13, the central polishing rate of the wafer 10 is gradually increased or decreased whereas the edge polishing rate of that is slightly changed. Therefore, the ratio of the central removed amount and the edge removed amount of the wafer is proportional to the non-uniformity of the wafer.

Accordingly, the typical polishing method for the wafer includes the following disadvantages:

1. At the beginning of using a new polishing pad, the central polishing rate is much faster than the edge polishing rate, which causing a poor non-uniformity. Therefore, it is necessary to use a lot of wafers for initially breaking in, a lot of slurry and about 5-10 hours to proceed the breaking in. Thus, it really takes time and wastes material.

2. At the last phase of the polishing pad, the difference between the central polishing rate and the edge polishing rate is too big and over the specification limit. It is necessary to replace the polishing pad, so the life time of the polishing pad is short.

3. The non-uniformity of the wafer is a critical indicator for the flatness of the wafer. However, the non-uniformity of the wafer according to the prior art only can be controlled in the specification limit, and cannot achieve a preferred condition.

Therefore, the purpose of the present invention is to develop a method to deal with the above situations encountered in the prior art.

SUMMARY OF THE INVENTION

It is therefore an object of the present invention to propose a polishing method using a dynamic feedback recipe for reducing an initial time of breaking in.

It is therefore another object of the present invention to propose a polishing method using a dynamic feedback recipe for achieving a preferred non-uniformity of the wafer.

It is therefore an additional object of the present invention to propose a polishing method using a dynamic feedback recipe for stabilizing a polishing rate of the wafer.

It is therefore an additional object of the present invention to propose a polishing method using a dynamic feedback recipe for increasing up time of the production machine, the producing yield, and reducing the cost.

According to the present invention, there is proposed a polishing method using a dynamic feedback recipe. The polishing method includes steps of providing a first recipe, polishing a first wafer according to the first recipe, measuring the first wafer to obtain a first determined data from the first wafer, calculating a second recipe according to a specific equation and the first determined data, and replacing the first recipe with the second recipe and polishing a second wafer according to the second recipe.

Preferably, each of the first wafer and the second wafer comprises an integrated circuit (IC) thereon.

Preferably, the first recipe is a predetermined recipe.

Preferably, the first wafer is driven by a carrier and polished by a polishing pad via a relative motion. Preferably, the method further includes a carrier film disposed between the carrier and the first wafer for protecting the first wafer. Preferably, the second wafer is driven by a carrier and polished by a polishing pad via a relative motion.

Preferably, the polishing method is a chemical mechanical polishing method employing a chemical mechanical polishing apparatus.

Preferably, the specific equation is stored in a dynamic recipe calculating device.

Certainly, the first recipe and second recipe can be a rotation speed and a pressure of the carrier, a rotation speed and a pressure of a turn table in a polishing apparatus, a back side pressure (BSP), a slurry flow rate, a dressing time and a dressing pressure of a pad conditioner or a combination thereof.

Certainly, the first determined data can be obtained by a measuring apparatus which is disposed in the polishing apparatus or out of the polishing apparatus. Preferably, the first determined data is a ratio of a central removed amount and an edge removed amount of the wafer.

Preferably, the specific equation is y ₂=y₁+a (y₀−y₁)+b, and a is the first determined data, y is a recipe for adjusting, and b is a coefficient.

Preferably, the polishing method further includes steps of providing a plurality of wafers, measuring the second wafer to obtain a second determined data from the second wafer, calculating a third recipe according to the specific equation and the second determined data, replacing the second recipe with the third recipe and polishing a third wafer according to the third recipe, and repeating the measuring step, the calculating step, and polishing step to the plural wafers till the plural wafers are polished to obtain a plurality of polished wafers. Preferably, the specific equation is y _i+2=y_i+1+a (y_i−y_i+1)+b, and a is the first determined data, y is a recipe for adjusting, i is an integer from 0 to n, and b is a coefficient.

Preferably, the polishing method further includes a testing step after polishing for a certain period of time. The testing step preferably includes providing a test wafer selected from the plurality of polished wafers, polishing the test wafer according to a testing recipe, and calculating a removed amount of the test wafer to obtain a polishing rate and an uniformity of the test wafer for determining whether to change the polishing pad. Certainly, the test wafer is a blank wafer having a film thereon.

The present invention may best be understood through the following description with reference to the accompanying drawings, in which: [0024]

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cutaway view illustrating polishing apparatus according to the prior art; [0025]
FIG. 2 is a flow chart illustrating a polishing method using a dynamic feedback recipe according to the present invention; and [0026]
FIGS. [0027] 3A-3B are block diagrams illustrating a polishing method using a dynamic feedback recipe according to preferred embodiments of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 2 is a flow chart illustrating a polishing method using a dynamic feedback recipe according to the present invention. As shown in FIG. 2, after changing a new polishing pad, a blank wafer is provided for initially breaking in. Sequentially, a first wafer is polished by using a first recipe. After measuring the first wafer which has been polished to obtain a determined data, a second recipe is obtained by a specific equation. The second recipe is transferred to a chemical mechanical polishing apparatus for replacing the first recipe and is used for polishing a second wafer. After measuring the second wafer which has been polished to obtain a second determined data, a third recipe is obtained by the specific equation. The third recipe is transferred to a chemical mechanical polishing apparatus for replacing the second recipe and is used for polishing a third wafer. Accordingly, a fourth, fifth . . . wafers are polished by the feedback recipes. The first recipe is a predetermined recipe which is tuned by users. The predetermined recipe can be changed according to the particular requirement. [0028]
After a certain period of time or a bath of wafer is polished, a testing step is proceeded to decide whether the polishing pad should be changed or not. The testing step includes providing a test wafer selected from the polished wafers, polishing the test wafer according to a testing recipe, and calculating a removed amount of the test wafer to obtain a polishing rate and an uniformity of the test wafer for determining whether to change the polishing pad. The test wafer is a blank wafer with a film thereon. The testing recipe is obtained by tuning. The certain time and the testing recipe can be changed according to the particular requirement. [0029]
The chemical mechanical polishing apparatus includes a carrier to drive the wafer for polishing by a polishing pad via a relative motion. The carrier has a carrier film between the carrier and the wafer for protecting the wafer. Each wafer has an integrated circuit thereon. [0030]
The above recipes includes a carrier rotation speed, a carrier pressure, a rotation speed and a pressure of a turn table in the polishing apparatus, a back side pressure (BSP), a slurry flow rate, a dressing time and a dressing pressure of a pad conditioner or a combination thereof. [0031]
The specific equation stored in a dynamic recipe calculating device is y[0032] _i+2=y_i+1+a (y_i−y_i+1)+b, wherein a is the first determined data, y is a recipe for adjusting, i=0˜n and b is a coefficient. The first determined data is a ratio of a central removed amount and an edge removed amount of the wafer.
As shown in FIGS. 3A and 3B, the predetermined preset recipe, e.g. the first recipe is inputted into a central information manager (CIM) [0033] computer 32, and transferred from the central information manager computer 32 to a dynamic recipe calculating device 31. A compensated recipe, e.g. the second recipe is calculated and obtained by the dynamic recipe calculating device 31 according to the specific equation and the first determined data, and transferred back to the central information manager computer 32. Finally, the compensated recipe is transferred to a chemical mechanical polishing apparatus 30 for polishing the wafer.
In addition, a measuring apparatus [0034] 33 is disposed in the chemical mechanical polishing apparatus 30 as shown in FIG. 3B whereas a measuring apparatus (not shown) is disposed out of the chemical mechanical polishing apparatus 30 as shown in FIG. 3A. Thus, the determined data is automatically obtained by the measuring apparatus 33 and is feedback to the dynamic recipe calculating device 31 as shown in FIG. 3B. However, when the measuring apparatus is out of the chemical mechanical polishing apparatus 30, the polished wafer is taken to the measuring apparatus by operators to measure the determined data, and the determined data is inputted to the central information manager computer 32 by operators. The measuring apparatus is in situ.
In sum, the polishing method using the dynamic feedback recipe according to the present invention can efficiently solve the problems of the long initial time for breaking in and the short life time of the polishing pad. In addition, the polishing method can achieve the preferred non-uniformity of the wafer, stabilize the polishing rate, increase the producing yield, and reduce the slurry consumption. [0035]
While the invention has been described in terms of what are presently considered to be the most practical and preferred embodiments, it is to be understood that the invention need not to be limited to the disclosed embodiment. On the contrary, it is intended to cover various modifications and similar arrangements included within the spirit and scope of the appended claims which are to be accorded with the broadest interpretation so as to encompass all such modifications and similar structures. [0036]

Claims

What is claimed is:

1. A polishing method using a dynamic feedback recipe, comprising steps of:

providing a first recipe;

polishing a first wafer according to said first recipe;

measuring said first wafer to obtain a first determined data from said first wafer;

calculating a second recipe according to a specific equation and said first determined data; and

replacing said first recipe with said second recipe and polishing a second wafer according to said second recipe.

2. The method according to claim 1, wherein each of said first wafer and said second wafer comprises an integrated circuit (IC) thereon.

3. The method according to claim 1, wherein said first recipe is a predetermined recipe.

4. The method according to claim 1, wherein said first wafer is driven by a carrier and polished by a polishing pad via a relative motion.

5. The method according to claim 4, further comprising a carrier film disposed between said carrier and said first wafer for protecting said first wafer.

6. The method according to claim 1, wherein said second wafer is driven by a carrier and polished by a polishing pad via a relative motion.

7. The method according to claim 1, wherein said polishing method is a chemical mechanical polishing method employing a chemical mechanical polishing apparatus.

8. The method according to claim 1, wherein said specific equation is stored in a dynamic recipe calculating device.

9. The method according to claim 1, wherein said first recipe and second recipe are selected from one group consisting of a rotation speed and a pressure of said carrier, a rotation speed and a pressure of a turn table in a polishing apparatus, a back side pressure (BSP), a slurry flow rate, a dressing time and a dressing pressure of a pad conditioner and a combination thereof.

10. The method according to claim 9, wherein said first determined data is obtained by a measuring apparatus which is disposed in said polishing apparatus.

11. The method according to claim 9, wherein said first determined data is obtained by a measuring apparatus which is disposed out of said polishing apparatus.

12. The method according to claim 1, wherein said first determined data is a ratio of a central removed amount and an edge removed amount of said wafer.

13. The method according to claim 1, wherein said specific equation is y₂=y₁+a (y₀−y₁)+b, and a is said first determined data, y is a recipe for adjusting, and b is a coefficient.

14. The method according to claim 1, further comprising steps of:

providing a plurality of wafers;

measuring said second wafer to obtain a second determined data from said second wafer;

calculating a third recipe according to said specific equation and said second determined data;

replacing said second recipe with said third recipe and polishing a third wafer according to said third recipe; and

repeating said measuring step, said calculating step, and polishing step to said plural wafers till said plural wafers are polished to obtain a plurality of polished wafers.

15. The method according to claim 14, wherein said specific equation is y_i+2=y_i+1+a (y_i−y_i−1)+b, and a is said first determined data, y is a recipe for adjusting, i=0˜n and b is a coefficient.

16. The method according to claim 14, further comprising a testing step after polishing for a certain period of time.

17. The method according to claim 16, wherein said testing step comprises:

providing a test wafer selected from said plurality of polished wafers;

polishing said test wafer according to a testing recipe; and

calculating a removed amount of said test wafer to obtain a polishing rate and an uniformity of said test wafer for determining whether to change said polishing pad.

18. The method according to claim 17, wherein said test wafer is a blank wafer having a film thereon.