KR101196651B1 - Double layered membrane in carrier head - Google Patents

Abstract

PURPOSE: A double layered membrane of a carrier head is provided to efficiently perform a polishing process by dividing the pneumatic pressure applied to the membrane into multiple regions. CONSTITUTION: A top membrane(210) includes a ring-shaped pressurization protrusion. A through hole is formed in the center of the top membrane. The upper side of the top membrane is embossed. A bottom membrane(220) is closely adhered to the top membrane. A through hole is formed in the center of the bottom membrane.

Description

Double membrane membrane of carrier head {DOUBLE LAYERED MEMBRANE IN CARRIER HEAD}

The present invention relates to a carrier head of a chemical mechanical polishing apparatus, and in particular, proposes a new carrier head in which a membrane providing a wafer adsorption surface is composed of a double membrane.

The chemical mechanical polishing (CMP) apparatus is a device for performing a wide-area planarization that removes a height difference between a cell region and a peripheral circuit region due to unevenness of a wafer surface generated by repeatedly performing masking, etching, To improve the surface roughness of the wafer due to contact / wiring film separation and highly integrated elements, and the like.

In such a CMP apparatus, the carrier head is a device of a membrane type carrier that directly or indirectly vacuum-adsorbs or accommodates the wafer with the polishing surface of the wafer facing the polishing pad before and after the polishing process. The head is mainly used. In addition, beyond the technical step of uniformly applying a uniform pressure on the surface of the wafer to evenly polish the film as a whole, a multi-zone division polishing method capable of variously adjusting the polishing profile of the wafer by applying locally different pressures to the surface of a single wafer Carrier head technology has been proposed.

1A and 1B show the structure of a multi-zone divided abrasive membrane-type carrier head H according to the prior art and an operating state when a predetermined air pressure P1 P2 is loaded into each division chamber C1 C2. Are schematically shown.

As shown in FIG. 1A, the membrane 110 installed on the bottom of the carrier head H has a ring-shaped membrane support stem 120 integrally formed on an upper surface thereof, so that the membrane support stem 120 is formed on the membrane support stem 120. By forming a structure in which the inner chamber (C1) and the outer chamber (C2) can be separated from each other, the membrane plate 11 and the membrane clamp 12, which is installed laminated on the upper inside of the membrane 110, and It forms the structure fixed by the retainer ring 3 which wraps around an outer periphery.

In the structure of the carrier head H described above, when predetermined air pressures P1 and P2 are respectively loaded through the central air passage 2 and the outer air passage 24, as shown in FIG. 1B, the air pressure P1 is inflated by applying a predetermined pressure to the inner chamber C1 and the air pressure P2 to the outer chamber C2, respectively, wherein the membrane support stem 120 is the membrane plate 11 and the membrane clamp ( Since the upper end is fixed by 12 and is not deformed according to the degree of expansion of each of the chambers C1 and C2, the inner chamber C1 and the outer chamber along the outer periphery of the lower end of the membrane support stem 120. A sharp circular inflection point 121 is formed between the boundaries of C2).

This inflection point 121 has a bad effect in performing the multi-polishing process by the local differential pressure load in order to implement a predetermined region division profile on the surface of a single wafer, that is, abruptly at the inflection point 121 region By unstable pressurization of the back surface of the wafer while achieving a shape and pressure change, an abnormal polishing phenomenon occurs due to a decrease in polishing rate at the region dividing boundary, which in turn lowers the semiconductor production yield.

In the above-described conventional carrier head, the wafer is adsorbed to the lower surface of the membrane bonded to the bottom part, and follows the indirect adsorption method for fixing the wafer. Indirect adsorption can cause wafer adsorption errors because the vacuum pressure in the chamber delivered to the wafer is relatively small compared to the pressure delivered to the membrane, which causes the wafer to move away from the carrier head during wafer movement or wafer desorption. Damage is likely to occur.

On the other hand, while it corresponds to an expensive part of the membrane in the carrier head, it is a consumable part that is no longer usable as it is partially damaged in the polishing process or the polishing process lasts for a long time, so regular replacement is inevitable. Replacement of membranes with complex structures, including fixtures for engagement with membrane clamps or bulkheads for multi-zone split polishing, requires disassembly and coupling of the components of the carrier head, reducing the life of the carrier head and increasing the efficiency of the polishing process. It is a factor which lowers.

Thus, there is a need for a new membrane that allows easy replacement of the spent membrane and does not damage components of the carrier head during the replacement process.

SUMMARY OF THE INVENTION The present invention has been made under the above technical background, and an object of the present invention is to provide a carrier head which is easy to adsorb and desorb wafers and has excellent polishing process efficiency.

Another object of the present invention is to provide a new carrier head which is easy to replace the membrane and is capable of multipart polishing.

It is another object of the present invention to provide a new double membrane membrane which is easy to align and firmly adheres to.

In order to achieve the above object, the present invention is a membrane for providing a wafer adsorption surface of the carrier head for a chemical mechanical polishing apparatus, the upper surface is formed with an annular pressing projection, the lower surface is formed flat and the upper portion having a through hole in the center The lower surface of the membrane and the lower surface which is in close contact with the lower surface of the upper membrane and provides a wafer adsorption surface is provided to provide a double membrane membrane of the carrier head comprising a lower membrane is formed flat and has a through hole in the center.

The upper membrane may be formed with two annular pressing protrusions at different positions on the upper surface. When air pressure is applied to the membrane, the pressure rises at the point where the annular pressure protrusion is disposed, the upper membrane and the lower membrane are in close contact with each other, and there is no room for air or liquid to penetrate between the lower and upper membrane surfaces. The membrane is integrated.

The lower membrane may further have an annular position fixing protrusion at a position corresponding to the central passage hole of the upper membrane. The positioning protrusions provide a reference for aligning the upper membrane and the lower membrane, and prevent gaps or spaced positions between the upper membrane and the lower membrane during polishing of the wafer.

In addition, the lower membrane edge portion has a vertical wing, the inner surface of the vertical wing may be formed with a protrusion for providing a receiving groove downward. This enables a firm contact between the upper membrane and the lower membrane without the use of separate complex coupling mechanisms or adhesive layers.

The present invention also provides a membrane for providing a wafer adsorption surface of a carrier head for a chemical mechanical polishing apparatus, wherein a partition wall is provided on the upper surface to provide a plurality of pressure application sections, and the upper surface of the membrane has a flat surface formed thereon, and The lower surface, which is in close contact with the lower surface of the membrane and provides a wafer adsorption surface, includes a lower membrane formed flat, wherein the lower membrane edge portion has a vertical wing, and an inner surface of the vertical wing has a protrusion for providing a receiving groove downward. It provides a double membrane membrane of the carrier head.

Accordingly, by dividing the air pressure applied to the upper membrane into multiple regions, polishing of various profiles is possible.In this process, the lower membrane relaxes abrupt changes due to the pressure difference at the boundary between the regions, improving the efficiency of the overall polishing process. Let's do it.

According to the present invention, by constructing the membrane of the carrier head of the direct adsorption method into a double membrane to improve the durability of the membrane, it is possible to perform an effective polishing process by dividing the air pressure applied to the membrane into multiple regions. The upper membrane and the lower membrane constituting the double membrane can be aligned in the correct position without a separate joining means. In the polishing process, the two membranes are firmly adhered to prevent penetration of the material into the adhesive surface.

In addition, the membrane that is prone to wear or damage due to long-term use of the carrier head requires periodic replacement. In this case, only the lower membrane which contacts the wafer and the upper membrane are used as it is, thereby greatly reducing the material cost of replacing the membrane. Can be.

1A and 1B are cross-sectional views showing a conventional carrier head.
Figure 2 is a half sectional view showing a carrier head of the present invention.
Figure 3 is a cross-sectional view showing a double membrane membrane of the carrier head of the present invention.
4 is a cross-sectional view showing an upper membrane of the present invention.
5 is a cross-sectional view showing a lower membrane of the present invention.
6a and 6b are cross-sectional views showing the coupling state of the upper membrane and the lower membrane.
7A and 7B are enlarged portions A and B of FIG. 6B;
8 is a cross-sectional view illustrating a multiparting chamber provided on an upper membrane.
Figure 9 is a schematic diagram showing the force acting on the pressing projection of the upper membrane.
DESCRIPTION OF THE REFERENCE SYMBOLS
200: carrier head 210: lower membrane
218: position fixing projection 220: upper membrane
221,223: bulkhead 225,226: pressure projection

Carrier head 200 for a chemical mechanical polishing apparatus according to an embodiment of the present invention has a structure as shown in the cross-sectional view of FIG.

The carrier head includes a drive body 202 that is connected to a drive shaft (not shown) and rotates inside the cover or housing, and a membrane is disposed on the bottom surface of the carrier head to provide the wafer 10 suction surface into the retainer ring 206. do. The membrane includes an upper membrane 220 which receives air pressure directly in the carrier head, and a lower membrane 210 which is indirectly pressurized in close contact with the upper membrane and provides a wafer adsorption surface.

The lower membrane and the upper membrane may each be secured to another component in the carrier head, for example the membrane holder 206.

3 shows a cross-sectional structure of the upper membrane 220 and the lower membrane 210 constituting the double membrane membrane according to an embodiment of the present invention.

The upper membrane 220 is a thin disk-type structure in plan view and has a through hole 220h through which air pressure is applied to adsorb the wafer. The lower membrane 210 is also a thin disk-type structure in plan view, and has a through hole 210h through which air pressure is applied to adsorb the wafer at the center thereof, and the through hole 210h is a through hole 220h of the upper membrane. It is smaller than the diameter. The wafer 10 is gripped or released from the holding state by a direct vacuum through the through holes 210h and 220h formed in the central portion.

The double membrane membrane of the present invention is capable of adsorbing the wafer at a small pressure by directly adsorbing the wafer by applying air pressure through a through hole in the center and improving the polishing quality by transferring a uniform pressure to the wafer polishing surface during wafer polishing. Can be.

In another embodiment of the present invention, the upper membrane and the lower membrane constituting the double membrane membrane may not include a central through hole.

The upper membrane 220 and the lower membrane 210 may be made of a flexible or elastic material such as silicone rubber, and each membrane may be made of the same material or different materials. While the upper and lower membranes are thinly formed, high hardness is required to maintain durability in the harsh polishing process, and the hardness of each membrane is preferably in the range of SHORE A 40-50.

The upper membrane and the lower membrane constitute a double membrane membrane with the lower surface of the upper membrane closely attached to the upper surface of the lower membrane, and may have separate coupling means for coupling and positioning of the two membranes. The lower membrane is preferably formed to have a larger overall length than the upper membrane to accommodate the upper membrane.

In the present invention, since the membrane of the carrier head is constituted by the double membrane of the upper membrane and the lower membrane, each of the upper membrane and the lower membrane can be made significantly lower in thickness than the membrane of the single membrane. In this case, it is possible to replace only the lower membrane which is mainly damaged during the polishing process, which can reduce material costs, facilitate membrane replacement, and significantly reduce the replacement time.

In the double membrane membrane according to the present invention, the upper membrane is directly subjected to air pressure transmitted through an air passage in the carrier head, and the lower membrane is indirectly supplied with air pressure through the upper membrane to pressurize the wafer, while Provide a surface to adsorb the wafer.

The upper membrane and the lower membrane may each be clamped to the other parts inside the carrier head by separate means, or alternatively they may clamp only the lower membrane with the upper membrane seated on the lower membrane upper surface.

Hereinafter, the bilayer membrane of the present invention will be described in more detail through specific examples, and a partial cross-sectional view corresponding to one-half of the symmetrical membrane cross section is shown.

4 illustrates an upper membrane. A plurality of vertical partitions 222 and 223 are formed on the upper surface 221a of the membrane, and the lower surface 221b is formed to be flat. The partitions 222 and 223 allow multi-zone divided polishing to divide the air pressure applied to the membrane into several zones and to transfer different air pressures to each zone. The number, size and location of the partitions can be varied in relation to the polishing process. A horizontally extending wing 224 is further formed at the end of the partition wall to clamp the upper membrane with other components in the carrier head. The thickness of the partition wall may be larger than the thickness of the upper membrane in order to ensure a physical bearing capacity that can withstand air pressure sufficiently.

Pressing protrusions 225 and 226 are also formed on the upper membrane top surface. The pressurizing protrusions 225 and 226 are formed in an annular structure in plan view and integrally formed with the membrane, and locally increase the area to which the air pressure delivered to the upper membrane is applied, which will be described later. Preferably, the pressing protrusion is formed on at least two positions on the upper membrane, and is formed near the center passage hole (corresponding to 226) and near the edge (corresponding to 225) of the upper membrane to induce firm adhesion between the upper membrane and the lower membrane. can do. Two or more pressing protrusions may be disposed substantially concentrically on the upper membrane upper surface.

Meanwhile, although not shown, a plurality of embossing may be formed on the upper membrane upper surface. This embossing is not only easy to handle the upper membrane, which is a thin membrane, but also more evenly distributes the air pressure applied to the upper membrane.

FIG. 5 shows the lower membrane, wherein the membrane upper surface 211a, which provides the surface on which the upper membrane is seated, is formed flat and has a center pass hole portion and an edge portion, respectively, to allow clamping with other components in the carrier head. Vertical vanes 212 and 213 are integrally formed. The membrane lower surface 211b providing the adsorption surface of the wafer is formed flat.

Since the lower membrane is in direct contact with the wafer to adsorb the wafer and is susceptible to chemical and physical damage during wafer polishing, the thickness of the lower membrane is preferably greater than that of the upper membrane.

A protruding portion 215 is provided near the edge portion vertical wing 213 of the lower membrane to provide the receiving groove 216 therein, and an end of the upper membrane may be inserted into the receiving groove. In addition, an annular positioning protrusion 218 may be formed near the vertical vane 212 of the central passage hole on the upper surface of the lower membrane. The positioning protrusions are formed at substantially the same position as the central through hole of the upper membrane when the upper membrane is seated on the lower membrane to fix the position of the upper membrane.

The process of seating the upper membrane on the upper surface of the lower membrane is schematically illustrated in Figure 6a. An end of the upper membrane is inserted below the protrusion 215 of the lower membrane, and the upper membrane center passage hole is fitted into the positioning protrusion 218 of the lower membrane.

The combined upper and lower membranes are as shown in Figure 6b. The engagement state of the central passage hole portion A of the upper membrane is shown in the enlarged view of FIG. 7A, and the engagement state of the upper membrane edge portion B is shown in the enlarged view of FIG. 7B. As such, the double membrane membrane according to the present invention is completed by the upper membrane and the lower membrane are in close contact with each other by fitting coupling. There is no need for a separate adhesive or bonding means in this process, so that the lower membrane and the upper membrane can be easily separated after the polishing process is completed. In the polishing process, the upper membrane and the lower membrane are substantially integrated due to the air pressure applied to the upper membrane, and it is difficult for air or liquid to penetrate the contact surface.

Figure 8 illustrates a plurality of pneumatic chambers provided by the bilayer membrane of the present invention. The chambers C1 to C5 of various regions exist in the membrane by the vertical partition wall of the upper membrane, and air pressures having different pressures may be applied to the respective chambers. Sophisticated multi-division polishing is possible by supplying an appropriate air pressure into each of the chambers and applying an indirect pressure to the back surface of the wafer. The vertical bulkheads providing the plurality of chambers are formed in an annular structure in plan view, each partition wall being arranged substantially concentrically in the upper membrane.

On the other hand, the upper membrane providing the plurality of chambers greatly reduces the formation of a sharp inflection point at the boundary of the region-divided polishing profile according to the air pressure applied to each chamber during the polishing process by bringing the lower membrane into close contact with the lower surface. Therefore, it is possible to smoothly implement the desired polishing profile by eliminating the abnormal polishing phenomenon due to the change of the polishing rate at the chamber boundary, and to maintain the polishing rate stably for all regions.

In the polishing process, the contact surface between the upper membrane and the lower membrane needs to be firmly adhered to prevent penetration of liquid such as air or polishing slurry. In the present invention, the annular pressurization formed on the upper membrane exerts a locally larger force on the lower membrane to prevent the penetration of this material.

Referring to FIG. 9, a process in which the air pressure P is applied to the upper membrane in a state where the upper membrane 220 and the lower membrane 210 constitute a double membrane is illustrated. The pressing protrusion protrudes above the upper membrane to provide a larger surface area compared to the other parts. Therefore, when the same pressure is applied to the upper membrane, the pressure transmitted to the lower membrane acts to make the region X in which the pressing projection is located larger than the other portion N. As a result, a greater adhesion force is generated between the upper membrane and the lower membrane at the portion where the pressing projection is formed, and there is no room for other foreign substances or air to penetrate the adhesive surface of the upper membrane and the lower membrane. On the other hand, since the upper and lower membranes do not have an adhesive layer between the opposing surfaces, they can be easily separated into independent membranes once the air pressure applied to the upper membrane surface is removed.

The present invention has been exemplarily described through the preferred embodiments, but the present invention is not limited to such specific embodiments, and various forms within the scope of the technical idea presented in the present invention, specifically, the claims. May be modified, changed, or improved. For example, the lower membrane edge portion may be formed in various forms, and the configuration in which the upper membrane is fitted in the gap therebetween has been exemplified, but various modifications such as the end of the upper membrane being bent to contact the edge portion of the lower membrane Can be.

Claims (15)

A membrane providing a wafer adsorptive surface of a carrier head for a chemical mechanical polishing apparatus, the membrane comprising:
An upper membrane having an annular pressing protrusion formed on an upper surface thereof, and a lower surface thereof being flattened and having a through hole in the center thereof;
The lower surface closely contacting the lower surface of the upper membrane and providing the wafer adsorption surface includes a lower membrane that is flat and has a through hole in the center thereof.
Double membrane membrane of the carrier head. The double membrane membrane of a carrier head according to claim 1, wherein the upper membrane has two annular pressing protrusions formed at different positions on an upper surface thereof. The double membrane membrane of a carrier head according to claim 1, wherein the lower membrane has an annular position fixing protrusion formed at a position corresponding to the central through hole of the upper membrane. The double membrane membrane of a carrier head according to claim 1, wherein the hardness of the upper membrane and the lower membrane is in the range of SHORE A 40-50. The double membrane membrane of a carrier head according to claim 1, wherein said lower membrane is thicker than said upper membrane. The double membrane membrane of a carrier head according to claim 1, wherein the upper membrane has a plurality of partition walls formed on an upper surface thereof. The double membrane membrane of a carrier head according to claim 6, wherein the thickness of the partition wall is larger than the upper membrane thickness. The double membrane membrane of a carrier head according to claim 1, wherein the upper membrane upper surface is embossed. 2. The double membrane membrane of a carrier head according to claim 1, wherein the lower membrane edge portion has a vertical wing, and an inner surface of the vertical wing has a protrusion for providing a receiving groove downward. A membrane providing a wafer adsorptive surface of a carrier head for a chemical mechanical polishing apparatus, the membrane comprising:
A partition wall is formed on the upper surface to provide a plurality of pressure application sections, and the lower surface is formed with a flat upper membrane;
The lower surface closely contacting the lower surface of the upper membrane and providing the wafer adsorption surface includes a lower membrane formed flat;
The lower membrane edge portion has a vertical vane, and an inner surface of the vertical vane has a protrusion for providing a receiving groove downward.
Carrier head of chemical mechanical polishing device. The carrier head of claim 10, wherein the upper membrane has an annular pressing protrusion formed on an upper surface thereof. The carrier head of claim 10, wherein the lower membrane has an annular positioning protrusion formed on an upper surface thereof. The carrier head of claim 10, wherein the upper membrane and the lower membrane have a through hole formed at a center thereof. The carrier head of claim 10, wherein the lower membrane is thicker than the upper membrane. 15. The carrier head of claim 13, wherein a vacuum for directly holding a wafer is applied to the through hole penetrating the center of the lower membrane and the upper membrane.

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