TWI243736B - The method for controlling a chemical mechanical polishing procedure - Google Patents

Abstract

This invention relates to a method for controlling a chemical mechanical polishing (CMP) procedure, more particularly, to a method for controlling a chemical mechanical polishing procedure by using an optical detecting system to detect the scattering light and the reflex light, which are radiated from the surface of the polished wafer. The present invention uses the optical detecting system to detect the scattering light and the reflex light, which are radiated from the surface of the polished wafer momentarily. The optical detecting system can judge the proceeding rate of the CMP procedure and can control the parameters of the CMP procedure, such as the rotating rate of the polishing pad or the pressure, which is brought to bear on the polished wafer by the head, by using this detected information to proceed the precision CMP procedure. The optical detecting system will judge the polishing end point of the CMP procedure more accurately by analyzing the scattering light and the reflex light, which are radiated from the surface of the polished wafer momentarily, to avoid the defects in scratch, dishing, or erosion which will be occurred on the surface of the polished wafer to affect the qualities of the wafer's surface.

Description

1243736 V. Description of the invention (1) 5-1 Field of the invention: The present invention relates to a method for controlling a chemical mechanical polishing process, and more particularly to a method for detecting scattered light waves and reflected light waves on the surface of a wafer to be polished by using an optical detection system A method for controlling the chemical mechanical polishing process to avoid scratches, dishing, and defects in the surface of the wafer being polished that would affect the surface quality of the wafer. 5-2 Background of the Invention: The chemical mechanical polishing (CMP) process is similar to the wafer machine board polishing process that has more than 20 years of history. Chemical mechanical polishing has become a key technology for flattening of the world's major integrated circuit companies. The first figure is a schematic view of a conventional chemical mechanical polishing process, in which a polishing pad 1 10 is arranged above the polishing platform 100, and an abrasive distribution system 300 uniformly distributes the abrasive 3 1 0 on the polishing pad 110. Below the grinding platform 100 is a rotating spindle 105, which is used to drive the grinding platform 100 to rotate. A wafer 2 1 0 attached to the carrier 2 00 faces downward and contacts the polishing pad 1 1 0 on the polishing platform 1 0. The carrier 2 0 0 has another rotation axis 2 0 5 to drive the crystal. The circle 2 1 0 rotates. During the chemical mechanical polishing process, the mechanism of the mutual movement between the wafer surface film, the abrasive, and the polishing pad includes mechanical and chemical interactions. Therefore, under the same machine, different abrasives and polishing pads may be required to match the material characteristics of the wafer surface film.

1243736 V. Description of the invention (2) Combination. Chemical mechanical polishing process ^: The schematic diagram of the principle of the process is as shown in the t = body process in which the purpose of the process is to flatten and have uneven surfaces. The second wafer 210 has a component 230 facing downward. On a silicon wafer? An example is a gold structure such as the dielectric layer 22 in a damascene process. There are other semiconductors between the grinding metal 230 and the metal. From the figure, it can be seen that the load of the clams 3 10 under the metal 230 and the polishing pad 110 produces some shapes. The circle 2 1 0 is subjected to a reaction, and the silicon wafer surface " abrasive is polished and the chemically coated metal 2 3 0 is flattened. However, the aforementioned chemical machine old I, IS 此 # # κ Θ The branch grinding process is not in line with the actual mass production. This is a kind of manufacturing equipment that uses a multi-headed i. Become new, as shown in the third San E to the third E picture. In the figure, one or more grinding tools 1 V,. ^, As described above, have multiple wafers polished at the same time. Such a batch processing method has a significant improvement in productivity. When a traditional chemical mechanical polishing machine is in operation, the pressure of the wafer being polished by the carrier and the rotation speed of the rotating platform are determined by the wafer's polishing performance and polishing results, and the polishing pad used also needs to be Use polishing pads of uniform density and hardness as appropriate. At present, in the chemical mechanical polishing process, a number of methods have been used to determine the polishing end point of the chemical mechanical polishing in order to avoid the occurrence of over-grinding defects. Such methods are, for example, optical (p h 〇 t 〇) and motor current (m 〇 t 〇 r c u r r e n t). But currently such methods cannot do

Page 7 1243736 V. Description of the invention (3) To the instant (i η-situ) feedback, defects that cause scratches, dishing, and abrasion will still occur on the wafer surface, so that the polished wafer is a Defective products, resulting in lower product quality. If the defects of scratch, dishing, and abrasion are too serious, the wafer must be re-processed for some processes to reduce the production efficiency of the process and increase the cost of production. Therefore, how to make the polished wafer surface a complete plane is an important issue today. 5-3 Purpose and Summary of the Invention: In view of the above-mentioned backgrounds of the invention, the traditional chemical mechanical grinding has many shortcomings. The present invention mainly provides a method, which basically uses an optical detection system to detect the ongoing chemical machinery at any time. The scattered light waves and reflected light waves emitted by the surface of the wafer to be polished during the grinding process, and the parameters of the chemical mechanical polishing process can be controlled at any time to avoid defects such as scratches, dishing, and abrasion on the wafer surface, so as to improve wafer polishing After the surface quality. Another object of the present invention is to use an optical detection system to detect scattered light waves and reflected light waves emitted from the surface of a wafer being polished during a chemical mechanical polishing process at any time, and to control parameters of the chemical mechanical polishing process at any time to avoid Defects such as scratches, dishing, and abrasion occur on the surface of the wafer, so that the surface of the wafer after chemical mechanical polishing becomes a complete plane. Another object of the present invention is to detect an

1243736 V. Description of the invention (4) Scattered light waves and reflected light waves emitted from the surface of the wafer to be polished during the chemical mechanical polishing process, and control the parameters of the chemical mechanical polishing process at any time to avoid scratches and dishes on the wafer surface Pitting and abrasion defects to reduce production costs. Another object of the present invention is to use an optical detection system to detect scattered light waves and reflected light waves from the surface of a wafer being polished during a chemical mechanical polishing process at any time, and to control parameters of the chemical mechanical polishing process at any time. Avoiding defects such as scratches, dish sinks, and worms on the wafer surface to increase production efficiency. According to the above-mentioned object, the present invention provides a method for detecting scattered light waves and reflected light waves emitted from the surface of a wafer to be polished during a chemical mechanical polishing process by an optical detection system at any time, and to control it at any time. The parameters of the chemical mechanical polishing process can avoid defects such as scratches, dishing, and abrasion on the wafer surface, so as to improve the surface quality of the wafer after polishing and make the surface of the wafer after the chemical mechanical polishing a complete plane. The invention can also reduce the cost of production and increase the efficiency of production. 5-4 Detailed Description of the Invention: Some embodiments of the present invention will be described in detail as follows. However, in addition to the detailed description, the present invention can be widely implemented in other embodiments, and

1243736 V. Description of the invention (5) The scope of the present invention is not limited, and the scope of the following patents shall prevail. Generally, when performing chemical mechanical polishing, a carrier is used to hold the wafer, so that the wafer is polished on a rotating polishing table. At this time, the carrier will also rotate to increase the uniformity of grinding. The wafer is polished by a grinding pad on a rotary polishing table and an abrasive added during polishing. The carrier used must apply a single pressure to the wafer to grind the wafer. If the rotation speed of the polishing table is faster and the pressure applied by the carrier to the polished wafer is greater, the material removal rate on the surface of the polished wafer will be faster, but the scratch defects on the polished surface will be Become more serious. If the rotation speed of the grinding table is slower and the pressure applied by the carrier to the wafer to be polished is smaller, the wafer to be polished will be slower and the material removal rate will be slower, which will affect the process rate. Round surfaces will achieve better surface quality. The surface of the surface of the g end is round. This wafer has just finished the process of filling the holes in a material layer 400 and filling the filling layer 42 in a material layer 400. Because there is a hole 4 1 in the material layer 4 00 μ a · ^ system ′, after the process of filling the filling layer 4 2 0, there is still a defect in the surface of the right grinding. Chemical mechanical research is performed to remove the filling layer 4 2 0 on the material layer on both sides of the hole 4 1 0, and the plane of the filling layer 42 0 is a smooth plane, and the filling layer 42 is filled with the entire hole 4 1 〇. In the traditional chemical mechanical polishing method, the carrier

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The fixed pressure is the rate at which the surface of the wafer is ground. And the flow, can only 'adjust the grinding V. Description of the invention (6) The wafer is given a rate to add the research of the round surface of the grinding table depending on the rotation of the polished crystal turntable or the needs of the electric motor process' The decision system determines the final removal rate for the grinding process. It will also take a grinding removal rate and a method of applying the end point of the wafer to judge the point and set the rotation. Therefore, the necessary pressure and rotation, such as optics, cannot be increased with the traditional use of the conventional method when the pressure layer of the fourth wafer is removed by a sudden increase or full removal. The rotation of this chemical mechanical polishing table is deeper. Scratches in the holes). If the carrier is slow, the wafer will be ground. However, when the effectiveness of this process is detected, the wafer of the traditional chemical pattern under investigation is larger, or the rate is more optical. When the method is reduced, the table must be polished immediately, and the process speed is faster, and the grinding is filled. The layer to be transferred to the surface of the filling layer of the wafer will become a situation that will cause the conversion rate. Therefore, the surface of the wafer that must be ground is mechanically ground. The filling layer rotates quickly into the grinding table. If other types are found, it is determined that the hole stops in the chemical machine because of the load. Therefore, the pressure of abrasion on the wafer surface is small. The speed is relatively smooth. To study mechanical grinding, you must use the method emitted by the hairpin and traditional grinding. The speed of light is faster when the process is running, or the grinding is performed by the filling tools on both sides. The wafer will follow the undeveloped defect (reference or grinding table is slower, and it can avoid grinding for too long. The optical detection of scattered light waves and the polishing end point determine the efficiency of the filling material if the carrier is applied. When it is the motor current The material layer has been finished. However, the surface with a high pressure and the shape before grinding is left at the rotation speed shown in Figure 5. After grinding, it is produced by the defects of I insects, and the measurement system is lowered. With the reflected light waves,

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1243736 V. Description of the invention (7) ---- a- And according to the difference of light waves, control the process parameters of chemical mechanical polishing at any time to improve the process operation efficiency and improve the surface quality of the wafer at the same time. In the present invention, an optical detection system is first installed on the polishing table, and one or more holes are set on the polishing table so that light can pass through the polishing table and be emitted to the surface of the wafer to be polished. This optical system is connected to a host computer that controls the chemical mechanical polishing parameters. The scattered light waves and reflected light waves emitted from the surface of the wafer to be polished are used to determine the progress of the chemical mechanical polishing process, and the process parameters of chemical and mechanical polishing are automatically compared. Make adjustments. In the example

It is possible to use single-wavelength + evening light, k-field light, or multi-wavelength white light, which does not limit the scope of the present invention. ^ I 1 If there is a light-polished surface with light from the wafers detected by abrasive wafers, the control surface will be ground when the hole is in the hole, and the high-rotation surface will be scattered by the system. At the time of a round table, the optically generated phase control host has shown a shot emitted by the vehicle at a stepped speed, because the detection of the shape of the strong surface is the opposite. The chemical pair is polished, and the acceleration (st ep light is irradiated here). With the condition, the light will be detected gradually, and when the plane shape of the machine is metal, the wafer will be polished more efficiently. ) To the surface of the wafer to be polished, the surface of the wafer is chemically polished, and the pressure of the chemically polished surface is measured. At this time, the condition of the round surface is formed at different positions. The wafer table notifies this situation after receiving the control host state to reduce the load, and then the mechanical grinding force and grinding are studied. Reflection continues, smooth plane, different geomechanics, grinded crystals

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1243736 V. Description of the invention (8) The pressure of polishing the wafer and / or reducing the rotation speed of the polishing table 'to carry out a fine polishing process on the wafer to be polished. When the metal on both sides of the hole is removed and the material layer is exposed, the optical detection system will prepare to measure that the intensity of the reflected light has dropped to a set value, so the chemical mechanical polishing process is automatically ended. At this time, the surface of the wafer to be polished is a smooth plane, and no flaws have occurred (refer to the sixth figure). Refer to the seventh figure, which is the flow king diagram of the present invention. First, the wafer is fixed on the polishing table by a carrier and the chemical mechanical polishing 5 10 is started. The optical preparation and testing system installed on the polishing table will begin to emit light on the surface of the wafer to be polished and detect the reflected light 5 2 0. The optical system starts to judge the intensity of the reflected light (i n te n s 1 f y) 5 3 0. When the measured intensity of the reflected light is greater than a standard value but there is a considerable difference, the chemical mechanical polishing is continued with the original process parameters. If the measured intensity of the reflected light is large ^ a standard value and the difference is small, reduce the pressure on the wafer being polished by the carrier and / or reduce the rotation rate 540 of the polishing table for a fine polishing process. The optical pick-up system continuously emits light on the surface of the wafer to be polished and detects & The optical system continuously judges the intensity of the reflected light (56). When the strength of the 1 ί ί ί ί line is completely smaller than the standard value and the difference is small, 彳 τ stops the mechanical grinding process 57. If the measured intensity of the reflected light is still greater than the -standard value, the fine polishing process will continue. Illustration. First use the reference to the eighth figure, which is the flow of the invention 1243736. V. Description of the invention (9) Fix the wafer on the polishing table and start the chemical mechanical polishing 6 1 0 ° Optical mounted on the polishing table The detection system will begin to emit light on the surface of the wafer being polished and detect scattered light 62. The optical system starts to judge the intensity of the reflected light and the scattered light (i n t e n s i t y) 6 3 0. When the measured intensity of the scattered light is greater than a standard value, the chemical mechanical polishing is continued with the original process parameters. If the intensity of the scattered light measured is less than a standard value, the pressure of the wafer being polished by the carrier is reduced and / or the rotation rate of the polishing table is reduced to 6 40 for a fine polishing process. The optical detection system continuously emits light on the surface of the wafer to be polished and detects reflected light 650. The optical system continuously judges the intensity of the reflected light 6 6 0. When the measured intensity of the reflected light is completely smaller than a standard value and the difference is small, the process of chemical mechanical grinding is stopped 570. If the measured intensity of the reflected light is still greater than a standard value, the fine polishing process will continue. In summary, the present invention provides a method for detecting scattered light waves and reflected light waves emitted from the surface of a wafer being polished during a chemical mechanical polishing process using an optical detection system, and controlling the chemical mechanical polishing process at any time. Parameters to avoid defects such as brake injury, dishing, and grinding on the surface of the wafer, so as to improve the surface quality of the wafer after grinding and to make the wafer surface after chemical grinding to a complete plane. The invention can also reduce the cost of production and increase the efficiency of production. It not only has practical effects, but also has a design that has not been seen before. It has improved efficacy and progress. Therefore, it has met the requirements of the patent law, and has written according to the law. Apply for it. For this reason, the reviewing committee members would like to examine the details in detail and pray that the grant of the patent may be granted as soon as possible.

1243736

Page 15 1243736 The drawings briefly explain the above-mentioned objects and advantages of the present invention. The following examples and diagrams will be used to explain in detail as follows, where: The first diagram is a schematic diagram of a conventional chemical mechanical polishing process; the second diagram is Schematic diagram of planarization provided by the chemical mechanical polishing process in the semiconductor process; Figures 3A to 3E are schematic diagrams of the surface layout of different polishing machines; Figure 4 is the surface of the wafer to be chemically mechanically polished The fifth picture is the defect caused by the traditional chemical mechanical polishing method and the traditional grinding termination point measurement method to cause abrasion on the wafer surface. The sixth picture is the chemical mechanical polishing method and the optical detection system in the present invention. A smooth plane is formed on the circular surface; the seventh figure is a flowchart of the method of the present invention; and the eighth figure is another flowchart of the method of the present invention. Representative symbols of the main parts:

Page 16 1243736 Brief description of the drawing 1 00 Grinding table 1 0 5 Rotating spindle 1 1 0 Grinding pad 2 0 0 Carrier 2 0 5 Rotating shaft 210 Wafer 2 2 0 Dielectric layer 2 3 0 Metal 3 0 0 Abrasive Distribution system 4 0 0 Material layer 4 1 0 Hole 4 2 0 Filler layer

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Claims (1)

In the scope of the patent application, 'the filling layer is located on the material layer and the hole and fills the hole, the grinding table rotates at a rotation rate; a pressure is applied on the wafer for a chemical mechanical polishing Manufacturing process; emitting a light on a polished surface of the wafer; an intensity and detecting and judging an intensity of the light scattering light; reducing the pressure and the rotation rate; continuously detecting and continuously judging the intensity of the reflected light ; And ending the chemical mechanical polishing process. 5. The method for controlling the chemical mechanical polishing process according to item 4 of the patent application, wherein the above-mentioned light is a single-wavelength laser light. 6. The method for controlling a chemical mechanical polishing process according to item 4 of the scope of the patent application, wherein the above-mentioned light is multi-wavelength white light. At least 7. A method for controlling a chemical mechanical polishing process, wherein the method includes: rotating a chemical machine to place a wafer on a polishing table, wherein the polishing table rotates at a rate; applying a pressure on the wafer for polishing A polishing process is performed at a rate; a light is emitted on a polished surface of the wafer; a strength of a reflected light formed by the light is detected and judged. I. page 19 1243736 6. The intensity of a scattered light in the scope of the patent application Reducing the polishing rate; and ending the chemical mechanical polishing process. 8. For the method for controlling the chemical mechanical polishing process in the scope of patent application item 7, wherein the above-mentioned light is a single-wavelength laser light. 9. For example, the method for controlling the chemical mechanical polishing process in the scope of patent application No. 7, wherein the light is white light with multiple wavelengths. 10. The method for controlling a chemical mechanical polishing process according to item 7 of the patent application, wherein the above-mentioned wafer includes at least one material layer. 11. The method for controlling a chemical mechanical polishing process according to item 10 of the patent application range, wherein the above-mentioned material layer includes at least one hole. 12. The method for controlling a chemical mechanical polishing process according to item 11 of the scope of patent application, wherein the material layer and the hole at least include a filler layer. 13. The method of controlling the chemical mechanical polishing process according to item 12 of the patent application, wherein the above-mentioned filling layer fills the hole. Page 20