TWI533374B - A focus ring that improves the uniformity of wafer edge etch rate - Google Patents

Description

Focus ring for improving wafer edge etch rate uniformity

The present invention relates to a plasma reaction chamber structure for plasma processing of a wafer, and more particularly to a focus ring for improving wafer edge etch rate uniformity.

In the plasma etch chamber, the focus ring is placed on the side of the electrostatic chuck and is a component that has a significant influence on the edge etch rate of the wafer. The shape, structure and positional material of the focus ring have an important influence on the electric field distribution and temperature distribution in the edge region of the substrate. The prior art uses a tantalum or tantalum carbide as a substrate to make a gas shower head. During the plasma etching process, these materials are plasma etched away over time, and the thickness is gradually thinned until no further use is required for new component replacement, or Existing components need to be reworked to meet basic functional requirements. Since the components such as tantalum carbide are mainly produced by chemical vapor deposition (CVD), the production conditions are very demanding, and the production speed is extremely slow, for example, it takes several days to grow a part, so the cost of the existing sprinkler is high. Poor economy. The focus ring material of the existing plasma processor which is matched with the gas shower head of tantalum or tantalum carbide material is mainly tantalum, tantalum carbide or tantalum compound such as tantalum oxide or tantalum nitride, which is similar to the substrate material in the plasma treatment process. Even if it is bombarded onto the surface of the substrate during bombardment, it will not cause contamination and cause chip failure. The prior art can obtain a more uniform plasma etching effect by using a ruthenium or osmium compound as an upper electrode and a focus ring material, but these materials are easily corroded during plasma processing, so the maintenance cost is high. Therefore, the industry needs a component with lower maintenance cost, and reduces the cycle and cost of component replacement on the basis of ensuring etching uniformity.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a focus ring that improves wafer edge etch rate uniformity, effectively improving wafer edge etch rate uniformity.

The present invention provides a focus ring for improving the uniformity of the edge etching rate of a wafer, which is disposed on the outer peripheral side of the substrate above the susceptor in a plasma etching chamber, in order to solve the problems of the prior art. a shower head (2) is disposed above the substrate, the focus ring includes a first portion surrounding the substrate, and a second portion surrounds the first portion on an outer side, wherein the upper surface of the first portion is made of a bismuth-containing material, The second part is made of bismuth-containing material. The material of the shower head described therein is a conductive metal, and the surface material thereof is a compound containing ruthenium.

In an embodiment of the invention, the base material of the focus ring is a bismuth-containing compound, and the upper surface of the first portion is covered with a layer of ruthenium-containing material.

In an embodiment of the invention, the base material of the focus ring is a bismuth-containing compound, and the upper surface of the first portion is covered with a layer of ruthenium-containing material.

In an embodiment of the invention, the first portion of the base material is tantalum or a niobium containing compound, and the second portion of the base material is a niobium containing compound, the first portion and the second portion being fixedly joined to form a focus ring.

In an embodiment of the invention, the upper surface of the second portion of the focus ring is higher than the upper surface of the substrate, and the focus ring further includes a first platform (12) having a lower height extending below the substrate. The first portion also includes a transition ramp connected between the platform and the second portion.

In an embodiment of the invention, the antimony-containing compound is SiC. The ruthenium containing compound is Y ₂ O ₃ or YF ₃ .

Compared with the prior art, the invention has the following advantages: effectively improving the uniformity of the edge etching rate of the wafer and improving the service life of the focus ring.

1‧‧‧ Focus ring

11‧‧‧Outer ring

111‧‧‧Outer ring

112‧‧‧Transition

113‧‧‧ upper surface

12‧‧‧ platform

120‧‧‧ inside ring

13‧‧‧Transition surface

2‧‧‧Sprinkler

1 is a cross-sectional view of a plasma etching chamber of a focus ring for improving wafer edge etch rate uniformity according to the present invention; FIG. 2 is a schematic diagram showing the principle of one embodiment of a focus ring for improving wafer edge etch rate uniformity according to the present invention; 3 is a schematic diagram of the second embodiment of the focus ring for improving the edge etch rate uniformity of the wafer according to the present invention; and FIG. 4 is a schematic diagram of the third embodiment of the focus ring for improving the edge etch rate uniformity of the wafer according to the present invention.

The present invention will be further described below in detail with reference to the accompanying drawings.

In the present invention, the material of the shower head 2 is made of a conductive material such as aluminum, and the surface thereof is provided with a compound containing ruthenium. Since the cost of aluminum is relatively low and the processing is convenient, the production cost is greatly reduced. The ruthenium-containing compound is not easily corroded, and the surface of the shower head 2 can be protected from plasma corrosion, so that the shower head 2 can be ensured for a long period of use. During the use of the gas shower head 2, a heating device (not shown) on the back of the gas shower head 2 heats the gas shower head 2, and the Y ₂ O ₃ material also needs to undergo a temperature rising process, which is experienced from 60~ A slow temperature rise of 120 ° C, while introducing a fluorine-containing gas, and replacing the Y ₂ O ₃ material with YF ₃ makes the showerhead surface resistant to plasma corrosion. Since the substrate of the gas shower head 2 of the present invention is made of aluminum or the like and has different electrical characteristics compared to the prior art, when the prior art Si or SiC is used as the focus ring material, the etch rate distribution exhibits an edge portion. The etch rate is significantly lower. To this end, the invention proposes a novel focus ring structure suitable for use in an aluminum substrate gas showerhead.

One of the examples:

As shown in FIG. 1, a focus ring 1 for improving wafer edge etch rate uniformity is disposed on an outer peripheral side of a substrate above a susceptor in a plasma etch chamber, and a shower head 2 is disposed above the substrate. The focus ring includes: an outer ring 11 and an inner ring including adjacent connections, the inner ring includes a platform 12 having a lower height and a transition bevel 13 through which the inner ring is connected to the inner ring a large height annular outer ring 11 enclosing the outer peripheral side of the substrate, wherein the surface of the transition surface 13 is coated or coated with a film of tantalum or a cerium-containing compound material (such as SiC); The material of the ring 1 is made of a plasma-resistant material such as Y ₂ O ₃ containing ruthenium, so that in addition to the portion of the transition slope covered with SiC, other exposed portions such as the platform 12 of the inner ring of the ring and the outer ring of the ring The surface material is a cerium-containing compound. The area covering the layer of SiC material can also be extended to the inner surface of the platform 12 adjacent the substrate. Thus, the focus ring of the Y ₂ O ₃ material improves the etch rate uniformity of the outer side of the substrate relative to the central region of the substrate. The upper surface of the substrate 12 adjacent to the substrate may be lower than the lower surface of the substrate during operation, that is, the platform 12 extends below the substrate, thereby preventing the polymer from growing on the back side of the substrate, on the outer ring 11 The surface may be higher than the upper surface of the substrate to prevent rapid diffusion of plasma within the reaction zone. Such a size structure causes the upper surface of the outer ring 11 to be closer to the plasma, and plasma that is evacuated from the plasma processing region above the substrate to the outside also flows through the outer ring 11, so that at the outer ring of the ring The plasma concentration will be higher relative to the top of the substrate. Conventional SiC materials, when having the same shape, are more susceptible to corrosion than the protrusions of the substrate until the entire focus ring 1 is no longer usable and needs to be replaced. The present invention also prevents the focus ring portion at the outer ring 11 from being rapidly corroded by using corrosion-resistant Y ₂ O ₃ in the most corrodible region.

Embodiment 2:

As shown in FIG. 2, the shape and structure are similar to those of the first embodiment, but the base material of the focus ring 1 is selected from ruthenium or a ruthenium-containing compound, and the outer ring 11 is formed because the surface of the ring slope 13 is ruthenium or a ruthenium-containing compound. The surface of the upper surface 113 is covered with a compound containing a ruthenium-containing material. Therefore, the etch rate uniformity of the edge of the wafer is significantly improved during etching, and etching can be performed by using a ruthenium-containing compound as an upper surface material. The rate uniformity is significantly improved. The focus ring is made of Si or SiC on the inner surface near the inner side of the substrate, and a layer is coated on the outer upper surface. The layer of bismuth material, the layer containing bismuth material may also be directly attached to the substrate of the focus ring containing bismuth material through a film containing enamel on the surface, and the film may be removed after a period of use, and then a new one is attached. The membrane can further reduce the cost of using the focus ring. According to the experimental data, the etch rate uniformity can be improved by 125% or more by using the ruthenium-containing compound as the surface material of the upper surface 113.

Third embodiment:

The focus ring 1 shown in Fig. 3 includes an outer ring 111, and an inner ring 120. Between the inner ring and the outer ring, a transition section 112 is included. The transition section 112 is disposed between the transition slope 13 of the inner ring 111 and the outer ring 111; the material of the inner ring 120 is bismuth or a bismuth-containing compound, and the material of the outer ring 111 is a compound of hydrazine. Therefore, the uniformity of the etching rate at the edge of the wafer is remarkably improved at the time of etching. According to experimental data, the etch rate uniformity can be improved by 125% or more by using the ytterbium-containing compound as the surface material of the upper surface 113.

In the above three embodiments, the ruthenium-containing compound is SiC, and the ruthenium-containing compound is Y ₂ O ₃ or YF ₃ . Among them, the ruthenium on the surface of the transition slope 13 or the ruthenium-containing compound containing the ruthenium compound and the upper surface 113 of the outer ring 11 may be adhered to the surface of the ring slope 13 by a polyimide film (so-called high-temperature adhesive tape). As well as the upper surface 113 of the outer ring 11, the material itself may be a cerium-containing compound or a cerium-containing compound.

Since the surface of the shower head 2 is provided with a ruthenium-containing compound, the uniformity of the edge etching rate of the wafer can be effectively improved by the above three embodiments, and the uniformity is significantly improved by the test, and the uniformity can be reduced from 12.66% to 5.61. %, the effect is obvious, the production cost is reduced, and the uniformity of etching is effectively improved.

In summary, the present invention improves the uniformity of the wafer edge etch rate uniformity, effectively improving the uniformity of the wafer edge etch rate. The ruthenium-containing compound and the ruthenium-containing compound according to the present invention refer to a material whose main component is Si/SiC/SiO or Y ₂ O ₃ /YF ₃ , and it is not excluded that other additional compounds are added for other effects, but the present invention The main role is the above materials. The main component means that the content of these effective ingredients in the focus ring member is more than 70%.

Although the present invention has been described in detail by the preferred embodiments thereof, it should be understood that the foregoing description should not be construed as limiting. Various modifications and alterations of the present invention will be apparent to those skilled in the art. Therefore, the scope of the invention should be defined by the appended claims.

11‧‧‧Outer ring

113‧‧‧ upper surface

12‧‧‧ platform

13‧‧‧Transition surface

Claims (8)

A focus ring for improving wafer edge etch rate uniformity, disposed on an outer peripheral side of a substrate above a susceptor in a plasma etch chamber, above which is disposed a shower head (2), wherein: The focus ring includes a first portion surrounding the substrate, and a second portion surrounding the first portion on an outer side, wherein the first portion upper surface is made of a ruthenium-containing material and the second portion is made of a ruthenium-containing material. The focus ring also includes a platform (12) having a lower height extending below the substrate, the first portion further including a transition bevel connected between the platform and the second portion. A focus ring for improving wafer edge etch rate uniformity as claimed in claim 1, wherein the material of the shower head (2) is a conductive metal whose surface is covered with a ruthenium-containing compound material. A focus ring for improving wafer edge etch rate uniformity as claimed in claim 2, wherein the base material of the focus ring is a ruthenium-containing compound, and the upper portion of the first portion is covered with a layer of ruthenium-containing material. A focus ring for improving wafer edge etch rate uniformity as claimed in claim 2, wherein the base material of the focus ring is tantalum or a germanium-containing compound, and the upper surface of the second portion is covered with a layer of germanium-containing material. A focus ring for improving wafer edge etch rate uniformity according to claim 2, wherein the first portion of the base material is ruthenium or a ruthenium containing compound, and the second portion of the base material is a ruthenium containing compound, the first portion A fixed connection with the second portion constitutes a focus ring. A focus ring for improving wafer edge etch rate uniformity according to claim 2, wherein the first portion of the base material is ruthenium or a ruthenium containing compound, and the second portion of the base material is a ruthenium containing compound, the first portion A fixed connection with the second portion constitutes a focus ring. A focus ring for improving wafer edge etch rate uniformity as recited in claim 1, wherein the second portion of the upper surface of the focus ring is higher than the upper surface of the substrate. The focus ring for improving wafer edge etch rate uniformity according to any one of claims 3 to 5, wherein the bismuth-containing compound is mainly composed of SiC. The focus ring for improving wafer edge etch rate uniformity according to any one of claims 3 to 5, wherein the ruthenium-containing compound has a main component of Y ₂ O ₃ or YF ₃ .