JP2021122896A - Elastic membrane - Google Patents

Abstract

To make contact pressure of a semiconductor wafer to an abrasive pad uniform, in an elastic membrane which forms a single closed space between the elastic membrane and an abrasive head.SOLUTION: A wafer holding elastic membrane 10 is fitted to an abrasive head 21 of a CMP device 20 and forms a single closed space 23 between the elastic membrane and the abrasive head 21. The elastic membrane includes: an inner rubber layer 111 made of a rubber and provided on an abrasive head-fitting side; an outer rubber layer 112 made of a rubber and provided on a wafer-holding side; and an intermediate rigid layer 113 provided between the inner rubber layer 111 and the outer rubber layer 112 and formed of a material that has a rigidity higher than those of the inner rubber layer 111 and the outer rubber layer 112.SELECTED DRAWING: Figure 2

Description

The present invention relates to an elastic film for holding a wafer attached to a polishing head of a CMP apparatus.

In a CMP apparatus used in a semiconductor device manufacturing process, an elastic film for holding a wafer is usually attached to a polishing head. This elastic film attracts and holds the semiconductor wafer by adjusting the pressure in the closed space formed between the elastic film and the polishing head. Then, the semiconductor wafer held by the elastic film is pressed against the polishing pad and polished. At this time, if the pressure contact force of the semiconductor wafer with the polishing pad is not uniform, a portion of the semiconductor wafer that is under-polished or a portion that is over-polished will occur. Therefore, by forming a plurality of closed spaces between the polishing head and the elastic film and adjusting the pressure for each closed space, the pressure contact force of the semiconductor wafer with the polishing pad is made uniform. ing. For example, Patent Document 1 discloses an elastic film in which a plurality of closed spaces are partitioned between the polishing head and an elastic membrane in which a diaphragm having high rigidity is embedded so as to straddle the adjacent closed spaces.

Japanese Patent No. 5236705

In the configuration in which a plurality of closed spaces are partitioned between the polishing head and the elastic film, the structure of the polishing head and the elastic film is also the pressure for each closed space for equalizing the pressure contact force of the semiconductor wafer with the polishing pad. Adjustment is also complicated. In addition, there is a concern that dust may be mixed in when the elastic film, which is a consumable item, is attached to the polishing head, or an attachment error may occur, and a large amount of man-hours are required for the attachment.

An object of the present invention is to equalize the pressure contact force of the semiconductor wafer with the polishing pad in the elastic film forming a single closed space with the polishing head.

The present invention is an elastic film for holding a wafer that is attached to the polishing head of a CMP device and forms a single closed space between the polishing head and the rubber inside, which is provided on the polishing head attachment side. A rubber layer, a rubber outer rubber layer provided on the wafer holding side, and a material provided between the inner rubber layer and the outer rubber layer and having higher elasticity than the inner rubber layer and the outer rubber layer. It includes a formed intermediate rigid layer.

According to the present invention, an intermediate rigid body layer having a higher rigidity than those is provided between the inner rubber layer and the outer rubber layer, so that the elasticity forms a single closed space between the inner rubber layer and the outer rubber layer. In the film, the pressure contact force of the semiconductor wafer with the polishing pad can be made uniform.

It is a perspective view of the elastic membrane which concerns on embodiment. It is sectional drawing of the elastic membrane which concerns on embodiment. It is a vertical cross-sectional view which shows the state which the elastic film which concerns on embodiment is attached to the polishing head of a CMP apparatus. It is a vertical cross-sectional view which shows the outer peripheral part of the membrane body of the elastic membrane which concerns on embodiment. It is a vertical cross-sectional view which shows the outer peripheral part of the membrane body of the modification of the elastic membrane which concerns on embodiment.

Hereinafter, embodiments will be described in detail.

1A and 1B show the elastic membrane 10 according to the embodiment. As shown in FIG. 2, the elastic film 10 according to the embodiment is used for a wafer holding application of a semiconductor wafer W which is attached to a polishing head 21 of a CMP apparatus 20 and is polished by a polishing pad 22.

The elastic film 10 according to the embodiment is formed by a disk-shaped film body 11, a tubular portion 12 integrally provided on the polishing head mounting side of the peripheral edge thereof in a vertical wall shape, and extending inward continuously at the upper end thereof. It is formed in a shallow-bottomed circular dish shape having an annular portion 13 integrally provided on the surface. The thickness of the membrane body 11, the tubular portion 12, and the annular portion 13 is, for example, 0.3 mm or more and 6 mm or less.

In the elastic film 10 according to the embodiment, the tubular portion 12 and the annular portion 13 are attached so as to engage with the polishing head 21 on the entire circumference thereof, and the film body 11 is eccentric of the circular polishing pad 22. It is arranged so as to face the position and forms a single closed space 23 with the polishing head 21. The semiconductor wafer W to be polished is arranged so that one surface is in contact with the elastic film 10 attached to the polishing head 21 and the other surface is in contact with the polishing pad 22, and the closed space 23 is subjected to negative pressure. By being attracted to and held by the elastic film 10, the polishing head 21 and the polishing pad 22 slide on the polishing pad 22 and are polished by rotating their axes.

The film body 11 of the elastic film 10 according to the embodiment has a rubber inner rubber layer 111 provided on the polishing head mounting side, a rubber outer rubber layer 112 provided on the wafer holding side, and their inner rubbers. It has a three-layer laminated structure including an intermediate rigid body layer 113 provided between the layer 111 and the outer rubber layer 112. The surface of the inner rubber layer 111 exposed to the polishing head mounting side and the surface of the outer rubber layer 112 exposed to the wafer holding side are both flat surfaces.

The inner rubber layer 111 and the outer rubber layer 112 are formed of crosslinked rubber. Examples of the rubber component of the crosslinked rubber forming the inner rubber layer 111 and the outer rubber layer 112 include silicone rubber, chloroprene rubber, EPDM, NBR, natural rubber, and fluororubber. From the viewpoint of the stability of the film structure of the film body 11, the inner rubber layer 111 and the outer rubber layer 112 preferably have at least the same rubber component of the crosslinked rubber forming them, and are formed of the same crosslinked rubber. It is more preferable to have.

The hardness measured by the type A durometer of the crosslinked rubber forming the inner rubber layer 111 and the outer rubber layer 112 is preferably 10 or more and 90 or less, and more preferably 30 or more and 75 or less. The hardness of this crosslinked rubber is measured based on JIS K6253-3: 2012.

The thickness of the inner rubber layer 111 and the outer rubber layer 112 is, for example, 0.1 mm or more and 2 mm or less. The thicknesses of the inner rubber layer 111 and the outer rubber layer 112 may be different, but are preferably the same from the viewpoint of the stability of the film structure of the film body 11.

The intermediate rigid body layer 113 is composed of a disk made of a material having a higher rigidity than the inner rubber layer 111 and the outer rubber layer 112. Examples of the material forming the intermediate rigid body layer 113 include a resin and a metal. Examples of the resin include thermoplastic resins such as polyetheretherketone resin (PEEK) and polyethylene terephthalate resin (PET); thermosetting resins such as phenol resin and epoxy resin. Examples of the metal include stainless steel such as SUS304. The intermediate rigid body layer 113 may be composed of a composite material of a resin layer and a metal layer.

When the intermediate rigid body layer 113 is made of resin, the hardness measured by the type D durometer is preferably 10 or more and 95 or less, and more preferably 50 or more and 95 or less. The hardness of this crosslinked rubber is measured based on JIS K7215-1986.

The thickness of the intermediate rigid body layer 113 is, for example, 0.02 mm or more and 2 mm or less. The thickness of the intermediate rigid body layer 113 may be the same as or different from the thickness of the inner rubber layer 111 and the outer rubber layer 112.

From the viewpoint of the stability of the film structure of the film body 11, the outer diameter of the intermediate rigid body layer 113 is slightly smaller than the outer diameter of the film body 11, and therefore, on the outside of the intermediate rigid body layer 113, the inner rubber layer 111 and the outer diameter are formed. It is preferable that the intermediate rigid body layer 113 is embedded between the inner rubber layer 111 and the outer rubber layer 112 by being bonded to the rubber layer 112. In this case, as shown in FIG. 3, when the width a of the joint portion between the outer inner rubber layer 111 and the outer rubber layer 112 of the intermediate rigid body layer 113 and the thickness of the film body 11 of the elastic film 10 are t. From the viewpoint of the stability of the film structure of the film body 11, 0.01 t ≦ a is preferable. On the other hand, from the viewpoint of equalizing the pressure contact force of the semiconductor wafer W with the polishing pad 22, which will be described later, a ≦ 10t is preferable, a ≦ 5t is more preferable, and a ≦ 3t is further preferable. preferable.

From the viewpoint of equalizing the pressure contact force of the semiconductor wafer W with the polishing pad 22, the intermediate rigid body layer 113 is provided in the entire region of the film body 11, and as shown in FIG. 4, the intermediate rigid body layer is provided on the side surface of the film body 11. It is preferable that 113 is exposed.

An adhesive layer may be provided between the intermediate rigid body layer 113 and the inner rubber layer 111 and / or the outer rubber layer 112 to chemically enhance the adhesion between them. Further, the surface roughness of the intermediate rigid body layer 113 may be increased to physically increase the adhesion between the inner rubber layer 111 and / or the outer rubber layer 112.

The tubular portion 12 and the annular portion 13 are preferably formed of the same crosslinked rubber that forms the inner rubber layer 111 and / or the outer rubber layer 112 of the film body 11.

The elastic film 10 according to the embodiment is, for example, an uncrosslinked rubber sheet for forming an inner rubber layer 111, a disk-shaped intermediate rigid body layer 113, and an uncrosslinked rubber layer 112 for forming an outer rubber layer 112 on a press die. It can be manufactured by laminating rubber sheets, preparing them, and press-molding them.

According to the elastic film 10 according to the embodiment of the above configuration, the polishing head 21 is provided with an intermediate rigid body layer 113 having a higher rigidity than the inner rubber layer 111 and the outer rubber layer 112. Although a single closed space 23 is formed between the wafer and the wafer W, the pressure contact force of the semiconductor wafer W with the polishing pad 22 can be made uniform. This is because the deformation of the elastic film 10 according to the pressure distribution in the single closed space 23 between the elastic film 10 and the polishing head 21 is reduced by the high-rigidity intermediate rigid body layer 113, and the polishing pad 22 of the semiconductor wafer W. It is considered that the pressure contact force with the force is made uniform.

In the above embodiment, the elastic membrane 10 is formed in a shallow circular dish shape, but the present invention is not particularly limited to this. For example, the elastic membrane has a tubular portion and an annular portion. It may be composed of only a non-membrane body.

The present invention is useful in the technical field of elastic films for holding wafers attached to the polishing head of a CMP apparatus.

10 Elastic film 11 Film body 111 Inner rubber layer 112 Outer rubber layer 113 Intermediate rigid body layer 12 Cylindrical part 13 Circular part 20 CMP device 21 Polishing head 22 Polishing pad 23 Sealed space W Semiconductor wafer

Claims (5)

An elastic film for holding a wafer, which is attached to the polishing head of a CMP apparatus and forms a single closed space between the polishing head and the polishing head.
The rubber inner rubber layer provided on the polishing head mounting side and
An outer rubber layer made of rubber provided on the wafer holding side,
An intermediate rigid body layer provided between the inner rubber layer and the outer rubber layer and formed of a material having a higher rigidity than the inner rubber layer and the outer rubber layer.
Elastic membrane with. In the elastic membrane according to claim 1,
An elastic film in which the inner rubber layer and the outer rubber layer are made of the same crosslinked rubber. In the elastic membrane according to claim 1 or 2.
An elastic film in which the intermediate rigid body layer is made of resin or metal. In the elastic membrane according to any one of claims 1 to 3.
An elastic film in which the intermediate rigid body layer is embedded between the inner rubber layer and the outer rubber layer. In the elastic membrane according to claim 4,
An elastic film having 0.01t ≦ a ≦ 10t, where t is the width a of the joint portion between the inner rubber layer and the outer rubber layer outside the intermediate rigid body layer and the thickness of the elastic film.

Images