TWI778676B - Blocker for ion beam etching chamber - Google Patents

Abstract

Disclosed is a blocker for anion beam etching chamber. The blocker comprises a discharge chamber. A grid component is disposed at the end of the discharge chamber. A blocker plate is installed in the discharge chamber and the blocker plate is disposed in the discharge chamber at the end near the grid component. The blocker plate comprises a ring segment and a blocker plate segment, the ring segment is engaged in the discharge cavity, and several small holes are distributed on the surface of the blocker plate segment. The present invention can effectively reduce the plasma density at the edge or inner ring, thereby improving the etching uniformity.

Description

Stoppers for Ion Beam Etching Chambers

The present invention relates to the field of integrated circuit manufacturing, and in particular, to a stopper for an ion beam etching chamber.

The ion beam etching (IBE) cavity is a device that uses a certain energy ion beam to bombard the surface of the material to sputter the surface of the material to achieve the etching effect. The main components of the IBE chamber are the ion source, neutralizer, stage and rotating motor. The ion source is the key component of IBE etching, including quartz cavity, radio frequency (RF) power supply, radio frequency matching device, radio frequency coil and 2-3 layers of grid (grid). During the etching process, reactive gases Ar, O2, etc. enter the discharge chamber of the quartz cavity, and plasma is generated by high-frequency wave ionization initiated by the RF coil. The ions are drawn out by the grid, focused into a beam, and then neutralized by the electrons emitted by the neutralizer into an ion beam that is electrically neutral and has a certain energy, and bombards the surface of the wafer on the stage to achieve etching.

Etching uniformity is an important parameter to characterize the uniformity of the etching pattern on the wafer surface, and is generally calculated by the range (NU) or standard deviation (sigma) of the etching rate at each point in the plane. For IBE chambers, the distribution of the plasma, the configuration of the etch chamber, especially The ion source grid assembly can have a major impact on etch uniformity. The ion source grid assembly is generally composed of a screen grid, an acceleration grid and a deceleration grid (some have no deceleration grid). As the anode in the discharge chamber, the screen grid can absorb the discharge electrons, form a discharge circuit, and play the role of focusing. The acceleration grid can extract positive ions, and the deceleration grid can effectively adjust the ion distribution. When the reactive gas is ionized in the quartz cavity, the plasma density decreases continuously along the radial direction. In order to ensure the uniformity of etching, the mesh size on the screen grid gradually increases along the radial direction to achieve better uniformity.

However, in the actual use process, under the condition that the fixed grid mesh remains unchanged, the etching uniformity that can be achieved by different process conditions such as ion beam voltage (BMV) is quite different. Chinese patent CN202297785U discloses an exhaust pipe structure that improves the uniformity of the process chamber of etching equipment. Chinese patent CN101465286 discloses an etching method for adjusting the uniformity of the etching rate on the surface of the wafer. By adjusting the supply or supply parameters of the etching reaction gas, the edge etching rate is increased so as to improve the etching uniformity. The above methods are all directional adjustment methods, and the adjustment range and direction for the center and edge of the wafer are relatively fixed, and the flexibility is poor.

The technical problem to be solved by the present invention is to provide a blocking member for an ion beam etching cavity, which can effectively reduce the plasma density at the edge or the inner circle, thereby improving the etching uniformity.

In order to solve the above technical problems, the present invention adopts the following technical solutions: a stopper for an ion beam etching cavity, comprising a discharge cavity, a discharge cavity end A grid component is installed in the discharge chamber, and a blocking piece is installed in the discharge cavity. The blocking piece is arranged at one end of the discharge cavity close to the grid component. The blocking piece includes a ring segment and a blocking segment. The ring segment is stuck in the discharge cavity. small holes.

Further, the diameter of the small hole gradually increases or decreases outward from the center of the blocking segment.

Further, the diameter of the small holes is between 1-5 mm.

Further, the blocking segment is divided into an inner ring and an outer ring, and the small holes are distributed on the inner ring.

Further, the thickness of the baffle is between 3-6mm.

Further, the length of the ring segment is between 8-15mm.

Further, the material of the baffle is selected from quartz or ceramics.

Compared with the prior art, the present invention adopts the above technical solution, and has the following technical effects: during the etching process, the size of the small holes at the edge of the ion source grid assembly gradually increases, and the achievable etching uniformity under different process conditions (BMV) is quite different. Adding a baffle in the discharge chamber 1 can effectively reduce the plasma density at the edge or inner circle, thereby improving the etching uniformity. After the baffle is installed, the Etching Rate (ER) of the outer ring is significantly reduced, and the uniformity can be adjusted.

1: discharge chamber

2: Baffle

21: Ring segment

22: Block Fragments

3: grid component

FIG. 1 is a schematic diagram of the overall structure of the first embodiment.

FIG. 2 is a cross-sectional view of the baffle plate and the discharge chamber in the first embodiment.

FIG. 3 is a schematic structural diagram of a blocking plate in the first embodiment.

FIG. 4 is a schematic structural diagram of a blocking plate in the second embodiment.

Below in conjunction with accompanying drawing, the technical scheme of the present invention is described in further detail:

Embodiment 1, a baffle for an ion beam etching chamber, as shown in Figures 1, 2 and 3, includes a discharge chamber, a grid component is arranged at the end of the discharge chamber, a baffle is installed in the discharge chamber, and the baffle is set At one end of the discharge chamber close to the grid component, the distance between the blocking plate 2 and the grid component 3 is 0-20 cm. The blocking piece includes a ring segment 21 and a blocking segment 22 , the ring segment 21 is clamped in the discharge chamber, and a plurality of small holes are distributed on the surface of the blocking segment 22 .

The diameter of the small hole gradually increases or decreases outward from the center of the blocking segment. The diameter of the small holes is between 1-5mm. The thickness of the baffle is between 3-6mm. The length of the ring segments is between 8-15 mm. The material of the baffle is selected from quartz or ceramics.

Embodiment 2, as shown in FIG. 4 , the blocking segment 22 is divided into an inner ring and an outer ring, and the small holes are distributed on the inner ring.

When the ionized gas is ionized in the discharge chamber 1, and the ion beam is extracted through the Grid assembly 3 for etching, the small holes in the baffle 2 can block the plasma in the discharge chamber 1, so that the edge plasma density is reduced, and the outer ring The etch rate is reduced, resulting in better overall etch uniformity.

In order to flexibly adjust the plasma density at the edge, the diameter of the small holes in the baffle 2 can be designed to be 1-5mm in different specifications, or can be designed as a ring without small holes. The diameter of the outer ring is 150-200cm, and the inner The circle diameter is 20-120cm.

In order to realize the adjustment of etching uniformity under the condition of low BMV, the baffle can be designed to have only the hole area in the inner ring. At this time, the plasma in the inner circle of the wafer is blocked, the plasma density is reduced, and the etching rate of the inner circle is reduced, so that the overall etching uniformity is improved. The inner ring baffle is also divided into a ring segment 21 and a stop segment 22. The ring segment 21 is used for fixing, and the stop segment 22 is connected and fixed on the ring segment 21 by 2-6 contact rods for blocking plasma and adjusting uniformity.

In order to facilitate the process and facilitate processing, the thickness of the baffle 2 should be selected between 3mm and 6mm, and the length of the ring segment 21 should be selected between 8mm and 15mm. The material of the baffle 2 should preferably be quartz or ceramic.

To sum up, during the etching process, the size of the small holes at the edge of the ion source grid assembly 3 gradually increases, and the etching uniformity that can be achieved under different process conditions (BMV) is quite different. Adding a baffle 2 in the discharge chamber 1 can effectively reduce the plasma density at the edge or inner circle, thereby improving the etching uniformity.

It will be understood by those skilled in the art that, unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. It should also be understood that terms such as those defined in the general dictionary should be understood to have meanings consistent with their meanings in the context of the prior art and, unless defined as herein, are not to be interpreted in an idealized or overly formal sense .

The above embodiments are only to illustrate the technical idea of the present invention, and cannot limit the protection scope of the present invention. Any changes made on the basis of the technical solution according to the technical idea proposed by the present invention all fall into the protection scope of the present invention. Inside. The embodiments of the present invention have been described in detail above, but the present invention is not limited to the above-mentioned embodiments, and various changes can be made within the scope of knowledge possessed by those of ordinary skill in the art without departing from the spirit of the present invention.

1: discharge chamber

2: Baffle

3: grid component

Claims (7)

A baffle for an ion beam etching chamber, comprising a discharge chamber, a grid assembly is arranged at the end of the discharge chamber, a baffle is installed in the discharge chamber, and the baffle is arranged in the discharge chamber close to the At one end of the grid assembly, the blocking piece includes a ring segment and a blocking segment, the ring segment is clamped in the discharge chamber, and several small holes are distributed on the surface of the blocking segment. The stopper for an ion beam etching chamber according to claim 1, wherein the diameter of the small hole gradually increases or decreases outward from the center of the stopper segment. The stopper for an ion beam etching chamber according to claim 1, wherein the diameter of the small hole is between 1 mm and 5 mm. The baffle for an ion beam etching chamber according to claim 1, wherein the baffle is divided into an inner ring and an outer ring, and the small holes are distributed on the inner ring. The baffle for an ion beam etching chamber according to claim 1, wherein the thickness of the baffle is between 3 mm and 6 mm. The stopper for an ion beam etching chamber as claimed in claim 1, wherein the length of the ring segment is between 8 mm and 15 mm. The baffle for an ion beam etching chamber according to claim 1, wherein the baffle is made of quartz or ceramics.

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