CN1218369C - Method for Reducing Defects and Slurry Residue in Chemical Mechanical Polishing of Copper Process - Google Patents

Abstract

A method for reducing defects and slurry residue in copper process chemical mechanical polishing. The method comprises grinding the wafer with the grinding slurry, grinding and cleaning the surface of the wafer with deionized water, lifting the wafer, cleaning the surface of the wafer with deionized water from bottom to top to eliminate the residual grinding slurry on the surface of the wafer, lowering the wafer, and grinding and cleaning the wafer again with deionized water. The method of the invention greatly reduces the problem of residual slurry in the chemical mechanical polishing manufacturing method of the copper process, greatly improves the production quality, reduces the production cost and greatly improves the yield.

Description

Method for Reducing Defects and Slurry Residue in Chemical Mechanical Polishing of Copper Process

technical field

The invention relates to a chemical polishing manufacturing method for integrated circuits, in particular to a method for reducing defects during chemical polishing of copper process.

Background technique

Chemical Mechanical Polish (CMP) has become a leading key technology for comprehensive planarization in advanced semiconductor manufacturing. Semiconductor manufacturing methods continue to improve, and when the line width of semiconductor elements enters the sub-micron or even finer field, more and more processing is done in the manufacture of integrated circuits, which often makes the surface have different uniformity and severe height differences, especially When the integration of integrated circuits increases rapidly, because the surface of the semiconductor structure cannot provide enough area to make the required interconnection (Interconnection), and when it is necessary to make a multilevel interconnection (Multilevel Interconnection), each deposition The flatness of the layer will have a great impact on the subsequent manufacturing. Not only will the electrical characteristics of the components be changed, but it will directly affect the reliability of the product. Therefore, various methods must be used to planarize the semiconductor structure in an all-round way, so as to improve the accuracy of the process and reduce the impact of the unevenness of the semiconductor structure.

Chemical mechanical polishing (CMP) has become a widely used method for planarizing semiconductor structures, and since the technology of chemical mechanical polishing has been greatly improved and developed, it can provide comprehensive planarization. Therefore, in current semiconductor manufacturing methods, chemical mechanical polishing is mostly used to planarize the semiconductor structure, so as to reduce the level difference of the surface of the semiconductor structure. Especially in the copper dual damascene (Dual Damascene) method, the chemical mechanical polishing method is used to planarize the copper film, so chemical mechanical polishing has become the most important key method for the performance of component production and post-manufacturing method connection. In the chemical mechanical polishing method of copper metal, because copper is extremely easy to oxidize, it is necessary to add an antioxidant to the chemical mechanical polishing method slurry, generally using benzotriazole (BTA) to form an organic Cu-BTA film to protect the copper metal. Due to the poor water solubility of BTA, and often after CMP is completed, it will condense into stains on the surface of the wafer, which will cause problems in the connection and device performance in the subsequent process. In the copper process, the defects after chemical mechanical polishing have become the key unfavorable factors in the production of integrated circuits. Therefore, how to reduce the defect rate after chemical mechanical polishing, reduce slurry residue, improve the output and quality of chemical mechanical polishing, so as to improve the follow-up process and product yield, are issues that semiconductor manufacturers are concerned about and valued.

Contents of the invention

In view of the above-mentioned background of the invention, in the dual damascene manufacturing method of copper, because copper is extremely easy to oxidize, BTA antioxidants are contained in the chemical mechanical polishing slurry, but due to the poor water solubility of BTA, it is easy to agglomerate into blocks Therefore, after the copper process CMP is completed, stains are often condensed on the wafer surface, which causes problems in the connection quality and component performance in the subsequent process. Defects after chemical mechanical polishing of copper process have become the key unfavorable factors in the production of integrated circuits.

The object of the present invention is a method for reducing defects and slurry residues in chemical mechanical polishing of copper process, which uses the method of head-up cleaning to clean the surface of the wafer during the chemical mechanical polishing process to reduce the problem of slurry residues.

Another object of the present invention is a method for reducing defects and slurry residues in copper chemical mechanical polishing, which is to reduce slurry residues and defective ratios on the wafer surface, thereby improving the quality and yield of chemical polishing.

According to the above-mentioned purpose, the present invention provides a method for reducing defects and slurry residues in copper chemical mechanical polishing, which is suitable for the comprehensive planarization manufacturing method of wafers performed by chemical mechanical polishing machines. This method includes: first, using a slurry to polish the wafer, then using deionized water to polish and clean the surface of the wafer, then lifting the handle of the chemical mechanical polishing machine and the wafer, and then using deionized water Clean the surface of the wafer from bottom to top to eliminate slurry residue on the surface of the wafer. Finally, lower the wafer and use deionized water to grind and clean the wafer again. Wherein the above-mentioned slurry includes the slurry with BTA antioxidant used in the copper process, and this method is particularly suitable for chemical mechanical polishing of the dual damascene copper thin film process.

The present invention uses the method of head-up cleaning to reduce the problem of slurry residue in the chemical mechanical polishing method of the traditional copper manufacturing process, so that the production quality is greatly improved, especially in the double damascene manufacturing method of copper, for the slurry with BTA residue The improvement effect is obvious, so that the defect rate of the chemical mechanical polishing method of the copper manufacturing process is greatly reduced, and the production cost is thus reduced, and the output can be greatly increased due to the effective control of the process time.

Description of drawings

Preferred embodiments of the present invention will be described in more detail with the help of the following figures in the following explanatory text, wherein:

1A to 1B are schematic diagrams of the chemical mechanical polishing head-up cleaning device of the present invention.

Explanation of figure number symbols:

110 deionized water 120 wafer handle

130 Wafers 140 Polishing Pads

150 turntable 160 deionized water

Detailed ways

As can be seen from the Background of the Invention, chemical mechanical polishing has become a widely used method for planarizing semiconductor structures. Especially in the dual damascene copper film manufacturing method, the chemical mechanical polishing method has become the most important key process for component production and connection performance of subsequent processes. And because copper metal is easily oxidized during the chemical mechanical polishing process, it is necessary to use a slurry with antioxidants. However, due to the poor water solubility of BTA, and the stains are often condensed on the wafer surface after the copper process CMP is completed, the defect rate in the subsequent process increases and the component performance is prone to problems. Slurry residue after chemical mechanical polishing of copper process has become a key unfavorable factor in integrated circuit production.

The present invention utilizes the device and method of head-up cleaning, and adds the method and device of head-up cleaning to the traditional chemical mechanical polishing method, so that the production quality is greatly improved, especially in the double damascene method of copper, for the slurry with BTA residue The improvement effect is obvious, so that the production cost is reduced, and the process cycle can be greatly reduced, which has an extremely important contribution to the production of semiconductors, especially the production of copper processes. The method and device of the present invention will be described in detail below with illustrations.

As shown in Fig. 1A, it is the schematic diagram of the chemical mechanical polishing head-up cleaning device of the present invention, the chemical mechanical grinding head-up cleaning device of the present invention utilizes the wafer handle 120 to clamp the wafer 130 and rotate and grind on the polishing pad 140, and The polishing pad 140 is driven by the turntable 150 . Similar to conventional chemical mechanical polishing, after the wafer polishing is completed, in order to remove the remaining slurry on the wafer, deionized water 110 is generally sprayed onto the surface of the wafer 130, and the grinding is continued for a period of time to remove the undissolved slurry. The slurry particles are dissolved to reduce the problem of slurry residue, and thus reduce bad defects and improve yield. However, due to the poor water solubility of BTA antioxidants and the tendency to agglomerate in chemical mechanical polishing in the copper manufacturing process, traditional cleaning methods cannot meet the production quality requirements. Generally speaking, semiconductor manufacturers often prolong the deionized water grinding and cleaning process to meet the process quality requirements. But even if the deionized water grinding time is prolonged, the quality has improved compared to the past, but it still cannot fully meet the quality requirements, and therefore, the process time has been lengthened a lot, and the production time of the product has thus been lengthened.

Please refer to Figure B, as shown in the figure, a schematic diagram of the chemical mechanical polishing head-up cleaning device using the present invention. In the deionized water grinding and cleaning process, the head-up cleaning device of the present invention lifts the wafer handle 120 and the wafer 130, and rinses the deionized water 160 upwards, and deionizes the wafer 130 directly from the bottom of the wafer 130. Water 160 is sprayed. The residue of the slurry originally adhered to the wafer 130 will be directly rinsed with deionized water and dropped off. In traditional manufacturing methods, the high defect rate due to slurry residue will be greatly reduced.

See Table 1 at the end of the specification, which compares the inspection results of the head-up cleaning method of the present invention with other existing cleaning methods. Method 200 is an existing manufacturing method. The steps are to use deionized water to grind and clean the wafer for 1 minute. Under the same yield standard, it is found that there are 983 defects on the wafer surface, and most of them are BTA residues. Therefore, the judgment is bad. Method 230 is to overcome the unfavorable situation of excessively high, prolonging the time of grinding and cleaning with deionized water in the manufacturing process, and using deionized water for grinding and cleaning for 4 minutes. It can be clearly seen from the data that the time for grinding and cleaning with deionized water is prolonged. After a period of time, the number of defects is effectively reduced. Under the same production benchmark, the number of defects is 105 pieces, which is about 1/9 of the original. Therefore, although the defect rate has been reduced, the process time has increased by nearly 4 times, and the number of defects is still slightly higher. Method 210 is to use deionized water for 1 minute of grinding and cleaning, and then perform 15 seconds of head-up cleaning. The process time is only increased by 15 seconds, but the number of defectives has been reduced by half, and about 497 defects have been improved, and about 486 defects have been improved. grain defects. The method 220 is to use deionized water to grind and clean for 1 minute, then perform head-up cleaning for 15 seconds, and then grind and clean for 1 minute. Although this method increases the process time by about 1 minute and 15 seconds, it effectively reduces the number of defects, making the number of defects only about 13, which is about 1.3% of the traditional manufacturing method 200, and is about 88% better than the method 230. %, and the time is much shorter than the 4 minutes of the method 230, so the benefits and cost reductions produced by it are obvious. And the result of the method 230 inspection, the size of the residual BTA is larger than the size of the residual BTA produced by the method 220 using the chemical mechanical polishing head cleaning device of the present invention.

Therefore, the chemical mechanical polishing head-up cleaning device of the present invention not only greatly reduces the defect rate of the chemical mechanical polishing method of the copper manufacturing process, but also greatly increases the output due to the effective control of the process time. As those skilled in the art understand, the above descriptions are only preferred embodiments of the present invention, and are not intended to limit the patent scope of the present invention; all other equivalents that do not depart from the spirit disclosed by the present invention are completed Any change or modification should be included in the scope of protection of this patent.

Table 1: the table below is to utilize the method for head-up cleaning of the present invention to compare with the inspection results of other existing cleaning methods method 200 210 220 230 step Deionized water for 1 minute Clean with deionized water for 1 minute and head up for 15 seconds Deionized water for 1 minute Rinse head up for 15 seconds Deionized water for 1 minute Deionized water 4 minutes Inspection result (bad number) 983 486 13 105 Remark BTA residue BTA residue BTA residue (small size) BTA Residue (Large Size)

Claims (10)

1. one kind is reduced the defective of chemical and mechanical grinding to produce coppor and the method for grinding slurry residual, and this method is suitable for work-table of chemicomechanical grinding mill carries out in the global planarization manufacture process of wafer, and this method comprises at least:

Utilization is ground slurry and is carried out this wafer grinding;

Utilize deionized water to grind for the first time and clean this wafer;

Rise this wafer;

Utilize deionized water direction from bottom to top to clean this wafer;

Fall this wafer; And

Utilize deionized water to grind for the second time and clean this wafer.

2. the method for claim 1 is characterized in that: the above-mentioned slurry that grinds also comprises the antioxidant BTA.

3. the method for claim 1, it is characterized in that: the above-mentioned deionized water that utilizes upwards cleans this wafer by the below, comprises to use deionized water by the below this wafer to be cleaned 15 seconds.

4. the method for claim 1 is characterized in that: above-mentioned utilize deionized water to grind for the first time and clean this wafer, comprise and use deionized water to carry out the grinding of this wafer and cleaned 1 minute.

5. the method for claim 1 is characterized in that: above-mentioned utilize deionized water to grind for the second time and clean this wafer, comprise and use deionized water to carry out the grinding of this wafer and cleaned 1 minute.

6. the method for claim 1 is characterized in that: above-mentioned wafer is the wafer lever clamping that utilizes this work-table of chemicomechanical grinding mill, moves and rotation.

7. the method for claim 1 is characterized in that: the cmp that also is suitable for the copper film-forming method of dual damascene.

8. method that comes back and clean, this method is suitable for work-table of chemicomechanical grinding mill carries out in the global planarization manufacture method of wafer, and this method comprises at least:

Utilization is ground slurry and is carried out the grinding of this wafer;

Utilize deionized water to grind and clean this wafer;

Rise this wafer; And

Utilize deionized water upwards to clean this wafer by the below.

9. as claim 8 a described method, it is characterized in that: the above-mentioned deionized water that utilizes upwards cleans this wafer by the below, comprises to use deionized water direction from bottom to top that this wafer was cleaned 15 seconds.

10. as claim 8 a described method, it is characterized in that: the cmp that is suitable for the copper film-forming method of dual damascene.