TW201624526A - Plasma processing device and plasma etching method - Google Patents

Abstract

This invention discloses a plasma processing device, which comprises a reaction chamber having a gas intake unit, a base carrying the substrate to be processed, a first gas concentration ring, and a movable second gas concentration ring. The first gas concentration ring comprises an inner ring body and an outer ring body. The outer ring surrounds the inner ring body and passes through at least one rib and connects with the inner ring body as a whole. The hollow portion between the inner and outer ring bodies and the hollow portion inside the inner ring body are provided for passing of processing gas and/or its plasma. When the second gas concentration ring moves to be attached on the lower surface of the first gas concentration ring, it completely shields the hollow portion between the inner and outer ring bodies and at the same time completely exposes the hollow portion inside the inner ring body. This invention can regulate the plasma distribution according to different processing requirements.

Description

Plasma processing device and plasma etching method

The present invention relates to a semiconductor processing apparatus, and more particularly to a plasma processing apparatus and a plasma etching method using the same.

Plasma processing equipment is widely used in various semiconductor manufacturing processes, such as deposition processes (such as chemical vapor deposition), etching processes (such as dry etching), and the like. Taking a plasma etching process as an example, by arranging electrodes in a reaction chamber of a plasma etching apparatus, an etching gas is supplied as a process gas to a reaction chamber, and electricity of a process gas is formed in the reaction chamber by applying radio frequency on the electrodes. Slurry, a dry etching process in which etching is performed by atomic groups, ions, and the like generated from the plasma.

In recent years, the use of plasma etching processes to form high aspect ratio structures, such as TSV 矽 through hole technology, is receiving more and more attention and research. The formation of a high aspect ratio structure typically involves two steps. First, a patterned etch process is used to form a patterned photoresist on the surface of the wafer as a mask layer, and then a plasma is generated by a suitable process gas and used. The etched area protected by the mask layer etches deep trenches. After etching the deep trenches, a blanket etching process that does not require a mask layer is performed to thin the formed deep trenches to form a high aspect ratio structure of a desired depth. However, in the patternless etching process, since the etching rate of the edge region and the intermediate region of the wafer is different, the etching rate of the edge region is faster, which causes the etching depth and top feature size of each high aspect ratio structure in the entire wafer range. Inconsistent feature sizes at the bottom, which in turn affect product yield. If the high-aspect ratio structure is patterned and etched without pattern etching in different chambers, the process efficiency is reduced and the cost is increased.

In order to solve the above problems, in the prior art, a movable shielding ring is disposed in the reaction chamber to reduce the bombardment of the plasma in the edge region, thereby improving the etching uniformity in the case of no pattern etching. As shown in FIGS. 1a and 1b, the plasma etching apparatus includes a reaction chamber 10 having an insulating cover 11 at the top of the reaction chamber 10 and a susceptor 14 for holding the substrate W to be processed at the bottom. The air intake unit 12 is disposed under the side wall insulating cover 11 of the reaction chamber 10 to provide a process gas. An inductive coupling coil 13 is disposed on the insulating cover plate 11. The coil is connected to a radio frequency source (not shown) through a matching device (not shown), and an alternating magnetic field is generated by passing a radio frequency current in the coil 13, thereby reacting An electric field is induced in the chamber 10 to ionize the process gas to form a plasma. A gas concentration ring 16 having an inner diameter of ΦD1 is disposed below the air intake unit 12. The gas concentration ring 16 can restrain the process gas and its plasma distribution in the vicinity of the air intake unit 12 according to the inner diameter thereof. A cover ring 15 is provided around the substrate W for protecting the susceptor 14 from plasma bombardment losses. The movable shadow ring 17 has a smaller inner diameter ΦD2 that is driven by the drive unit 18 to be positioned in a non-contact manner above the surface of the substrate W. According to the etching process requirement, when the pattern-free etching process is required, the shadow ring 17 is brought close to the gas concentration ring 16. Since the inner diameter of the shielding ring 17 is small, the process gas and plasma passed by the gas concentration ring 16 are limited to The shielding ring 17 is in the range, thereby preventing the plasma from contacting the periphery of the substrate and reducing the etching rate of the edge of the substrate; when the deep trench pattern etching process is required, the shielding ring 17 is brought close to the surface of the substrate W, and the gas concentration ring 16 makes the process gas and The plasma can diffuse and descend over a wide range.

However, when performing the deep trench pattern etching process, the shadow ring adjacent to the substrate also affects the plasma density of the edge region of the substrate W. In particular, when the inner diameter ΦD2 of the shadow ring 17 is smaller than the diameter of the substrate W, the deep trench profile is further caused. Poor topography control.

Therefore, it is desirable to provide a plasma processing apparatus capable of simultaneously improving the high aspect ratio structure topography control and the uniformity of no pattern etching.

SUMMARY OF THE INVENTION A primary object of the present invention is to overcome the deficiencies of the prior art and to provide a plasma processing apparatus and a plasma etching method capable of performing pattern etching and patternless etching processes in situ without affecting the etching uniformity and etching morphology of each etching process.

To achieve the above object, the present invention provides a plasma processing apparatus comprising a reaction chamber and a driving unit. The reaction chamber has an intake unit for inputting a process gas to the reaction chamber; a susceptor for mounting a substrate to be processed; a first gas concentration ring disposed at the air intake unit and the base Between the seats, comprising an inner annular body and an outer annular body, the outer annular body surrounding the inner annular body and being integrally connected with the inner annular body by at least one spoke, the inner annular body and the outer annular body a hollow portion between the hollow portion and the inner annular body for passing the process gas and/or its plasma; and a movable second gas concentration ring disposed on the outer peripheral side of the substrate and located on the substrate and The first gas is concentrated between the rings. The driving unit is configured to drive the second gas concentration ring to move vertically between a first position away from the first gas concentration ring and a second position attached to a lower surface of the first gas concentration ring; When the second gas concentration ring moves to the second position, it completely shields the hollow portion between the inner annular body and the outer annular body while completely exposing the hollow portion inside the inner annular body.

Preferably, the inner annular body, the outer annular body and the second gas concentration ring are coaxial rings.

Preferably, the outer diameter of the second gas concentration ring is larger than the inner diameter of the outer annular body, and the inner diameter of the second gas concentration ring is larger than the inner diameter of the inner annular body and smaller than the inner annular body. The outer diameter.

Preferably, the inner annular body has an inner diameter smaller than the diameter of the substrate, and the inner diameter of the second gas concentration ring is larger than the diameter of the substrate.

Preferably, the plurality of spokes are evenly distributed along the outer circumference of the inner annular body.

Preferably, the spokes have a width of 5-30 mm, the inner annular body has a width of 5-30 mm, and the hollow portion between the inner annular body and the outer annular body has a width of 10-100 mm.

Preferably, when the second gas concentration ring is moved to the first position, a vertical distance between a lower surface thereof and an upper surface of the substrate is 0-30 mm.

Preferably, the material of the first gas concentration ring and the second gas concentration ring is a metal or a dielectric material.

Preferably, the spokes are in the shape of a straight line, a diagonal shape or a curved shape.

The present invention also provides an etching method using the above plasma processing apparatus, the etching method comprising performing a deep trench pattern etching process and a patternless etching process in situ, comprising the steps of:

Positioning the second gas concentration ring to the first position;

Performing the deep trench pattern etching process;

Positioning the second gas concentration ring to the second position;

The patternless etching process is performed.

Compared with the prior art, the plasma processing apparatus of the present invention utilizes the lifting action of the movable second gas concentration ring to match the first gas concentration ring having the inner and outer annular bodies to adjust the passable range of the process gas and/or its plasma. In order to maintain the uniformity of the etching rate and the etched morphology in different processes, the process efficiency and product yield are improved.

In order to make the content of the present invention clearer and easier to understand, the contents of the present invention will be further described below in conjunction with the accompanying drawings. Of course, the invention is not limited to the specific embodiment, and general replacements well known to those skilled in the art are also encompassed within the scope of the invention.

2a and 2b show a plasma processing apparatus according to an embodiment of the present invention, it being understood that the plasma processing apparatus is merely exemplary, which may include fewer or more constituent elements, or an arrangement of the constituent elements. May be the same or different from the one shown in the figure.

Referring to FIG. 2a, FIG. 2b and FIG. 3, the plasma processing apparatus includes a reaction chamber 20. Above the reaction chamber 20 is an insulating cover 21, which is typically a ceramic dielectric material. An air intake unit 22 for inputting a process gas into the interior of the reaction chamber 20 is provided at a side wall of the reaction chamber 20 near the top. A susceptor 24 for mounting the substrate W to be processed is disposed at the bottom of the reaction chamber 20. An inductive coupling coil 23 is disposed above the outer side of the insulating cover 21, and an RF current is supplied to the coil 23 through a radio frequency source (not shown) to induce an electric field in the reaction chamber 20, thereby being introduced into the chamber by the air intake unit 22. The process gas is ionized and produces a plasma. In addition, in the present embodiment, the air intake unit 22 is formed at the side wall of the reaction chamber 20 near the insulating cover, but in other embodiments, it may be formed in the insulating cover, which is not limited in the present invention. A first gas concentration ring 26 and a movable second gas concentration ring 27 are also disposed in the reaction chamber 20. The material of the two gas concentration rings may be a metal such as aluminum; or a dielectric material such as ceramic or quartz. The first gas concentration ring 26 is fixed above the inside of the reaction chamber 20, between the air intake unit 22 and the susceptor 24. As shown in FIG. 3, the first gas concentration ring 26 includes an inner annular body 261 and an outer annular body 262 surrounding the inner annular body, and the outer annular body 262 is integrally coupled to the inner annular body 261 by at least one spoke 263. The shape of the spokes 263 may be a straight shape, a diagonal shape or a curved shape. Thus, the hollow portion 265 is formed between the inner annular body 261 and the outer annular body 262, and the hollow portion 264 is also formed inside the inner annular body 261. The two partial hollow portions 264, 265 pass the process gas and/or its plasma. The movable second gas concentration ring 27 is provided on the outer peripheral side of the substrate W between the substrate W and the first gas concentration ring 26, and is driven by the drive unit 28 to move up and down in the vertical direction. Specifically, the second gas concentration ring 27 is connected to the drive unit 28 through a support rod. The drive unit may include a motor, a cylinder, or the like that drives the second gas concentration ring 27 to move between a first position and a second position in the vertical direction. When the second gas concentration ring 27 is positioned at the first position, it is away from the first gas concentration ring, and preferably the vertical distance of the lower surface of the second gas concentration ring 27 from the upper surface of the substrate W is 0 to 30 mm. At this time, the process gas and/or its plasma passes through the hollow 265 between the inner annular body 261 and the outer annular body 262 of the first gas concentration ring 26 and the hollow portion 264 within the inner annular body 261. , as indicated by the dashed arrow in Figure 2a. Since the second gas concentration ring 27 is away from the first gas concentration ring 26, it does not affect the constraint range of the first gas concentration ring 26. In addition, the second gas concentration ring 27 is disposed around the outer peripheral side of the substrate W, and the edge of the substrate W is also Since the shielding effect is not generated, the process gas and/or its plasma reaches the entire surface of the substrate W. At this time, deep trench plasma etching can be performed, and the plasma density near the surface of the substrate W is not easily affected, and the edge region of the substrate W is etched. The profile of the deep trench is guaranteed. When the second gas concentration ring 27 is positioned at the second position, it is attached to the lower surface of the first gas concentration ring 26 to completely shield the hollow portion 265 between the inner annular body 261 and the outer annular body 262. The hollow portion 264 within the inner annular body 262 is completely exposed. Thereby, the hollow portion 265 is closed, and the process gas passing through the first gas concentration ring 26 and/or its plasma is confined within the range of the hollow portion 264, preventing part of the process gas and/or its plasma from reaching the substrate. The edge thus acts to shield the plasma from contacting the periphery of the substrate W, as indicated by the dashed arrow in Figure 2b. At this time, the sealing of the hollow portion 265 by the second gas concentration ring 27 can reduce the process gas at the edge of the substrate and/or its plasma distribution, and reduce the etching rate at the edge, thereby ensuring the etching uniformity of the entire substrate surface. Therefore, when the second gas concentration ring 27 is positioned at the second position, a pattern-free etching process can be performed.

In the present embodiment, the inner annular body 261, the outer annular body 262 and the second gas concentration ring 27 are three annular rings that are coaxial. As shown, the inner annular body 261 has an inner diameter of ΦD2, and the outer annular body 262 has an inner diameter of ΦD1. In order to move the second gas concentration ring 27 to the second position, the hollow portion 265 can be shielded but the hollow portion 264 is exposed. The outer diameter of the second gas concentration ring 27 should be larger than the inner diameter of the outer annular body 262, and the inner diameter should be larger than the inner diameter of the inner annular body 261 and smaller than the outer diameter of the inner annular body 261. For example, the inner diameter of the inner annular body 261 may be smaller than the diameter of the substrate W, thereby better shielding the process gas and/or its plasma from reaching the periphery of the substrate W when the pattern-free etching process is performed. The second gas concentration ring 27 is disposed around the outer side of the substrate W, and has an inner diameter larger than the diameter of the substrate W. Further, in order to stabilize the inner and outer annular bodies to each other, the spokes 263 may be provided in plural, as in the present embodiment, three, and are evenly distributed along the outer circumference of the inner annular body 261. It should be noted that in the present embodiment, although the inner annular body 261, the outer annular body 262, and the second gas concentration ring 27 have a coaxial ring structure, the present invention is not limited thereto. In other embodiments, inner annular body 261 and/or outer annular body 262 may also be rectangular rings or other shaped rings. The second gas concentration ring 27 is correspondingly designed according to the structure of the first gas concentration ring 261, and can adopt various shapes and size parameters as long as it can be attached to the first gas concentration ring 26 between the inner annular body and the outer annular body. The hollow portion 265 is entirely covered, but the hollow portion 264 inside the inner annular body may be entirely exposed.

On the other hand, in order to prevent the spokes and the inner annular body from blocking the process gas and/or its plasma which the first gas concentration ring can pass when the second gas concentration ring 26 is positioned at the first position, The inner annular body 261 and the spokes 263 are designed to reduce the occupied area as much as possible, so that the flow rate of the process gas and/or its plasma of the first gas concentration ring 26 is substantially similar to that of the spokeless and inner annular body. . Preferably, the width of the spoke 263 and the inner annular body 261 in the embodiment is much smaller than the width of the hollow portion 245, the width of the spoke 263 and the inner annular body 261 may be 5-30 mm, and the width of the hollow portion 245 is 10-100 mm. .

Referring to FIGS. 2a and 2b, the reaction chamber 20 further includes a cover ring 25 that surrounds the substrate W and covers the surface of the susceptor 24. The cover ring 25 and the surface of the base 24 (e.g., the side walls, the upper surface) are as close as possible to prevent the plasma from hitting the base 24, protecting the base 24 from loss. The cover ring 25 may be formed of an insulating material such as ceramic or quartz.

The plasma processing apparatus of the present invention is particularly suitable for performing deep trench pattern etching processes and patternless etching processes in situ. Next, please refer to FIG. 4, which shows the in-situ execution of deep trench patterns by the plasma processing apparatus of the present invention. A schematic diagram of a process of etching and a pattern-free etching process, which may specifically include:

Step 41: Positioning the second gas concentration ring to the first position;

In this step, the driving unit drives the second gas concentration ring to descend to the first position away from the first gas concentration ring.

Step 42: performing a deep trench pattern etching process;

In this step, a patterned photoresist is used as an etch hard mask to form a deep trench structure by a conventional plasma etching process. Since the process gas and/or its plasma can pass through the hollow portion between the inner annular body and the outer annular body and the hollow portion inside the inner annular body, the second gas concentration ring surrounds the substrate W. The outer peripheral side is disposed, so that when the process gas and/or its plasma reaches the entire surface of the substrate W, the plasma density near the surface of the substrate W is not easily affected, and the cross-sectional morphology of the deep trench etched in the edge region of the substrate W is ensured.

Step 43: Positioning the second gas concentration ring to the second position;

In this step, the driving unit drives the second gas concentration ring to rise to the second position to be attached to the lower surface of the first gas concentration ring.

Step 44: Perform a patternless etching process.

In this step, plasma etching is performed without using a hard mask to make the depth of the deep trench structure reach a desired depth. Since the second gas concentrating ring completely shields the hollow portion between the inner annular body and the outer annular body, the process gas and/or its plasma passing through the first gas concentrating ring is restricted to be hollow inside the inner annular body In the range of the part, part of the process gas and its plasma are prevented from reaching the edge of the substrate, thereby reducing the etching rate at the edge, thereby ensuring the etching uniformity of the entire substrate surface.

In summary, the plasma processing apparatus of the present invention adjusts the passable range of the process gas and/or its plasma by using the lifting action of the movable second gas concentration ring in conjunction with the first gas concentration ring having the inner and outer annular bodies. Therefore, different etching processes can be switched without changing or opening the reaction chamber, which reduces the maintenance time of the machine; at the same time, the uniformity of the etching rate and the etching morphology in each etching process are maintained, and the process efficiency is improved. And product yield.

The present invention has been described in terms of the preferred embodiments of the present invention, which are intended to be illustrative only, and are not intended to limit the scope of the invention. A number of changes and refinements are possible, and the scope of protection claimed herein should be based on the scope of the patent application.

10, 20‧‧‧ reaction chamber
11, 21‧‧‧ Insulating cover
12, 22‧‧‧Air intake unit
13, 23‧‧‧ coil
14, 24‧‧‧ Pedestal
15, 25‧ ‧ cover ring
16‧‧‧ gas concentration ring
17‧‧‧ shadow ring
18, 28‧‧‧ drive unit
26‧‧‧First gas concentration ring
261‧‧‧ inner ring
262‧‧‧ outer ring
263‧‧ spokes
264, 265‧‧‧ hollow
27‧‧‧Second gas concentration ring
41-44‧‧‧Steps
W‧‧‧Substrate ΦD1, ΦD2‧‧‧ Inside diameter

1a and 1b are schematic structural views of a plasma processing apparatus in the prior art;

2a is a schematic structural view of a plasma processing apparatus according to an embodiment of the present invention when deep trench etching is performed;

2b is a schematic structural view of the plasma processing apparatus according to an embodiment of the present invention when no pattern etching is performed;

3 is a plan view of a first gas concentration ring of a plasma processing apparatus according to an embodiment of the present invention;

Fig. 4 is a flow chart showing an etching method of a plasma processing apparatus according to an embodiment of the present invention.

20‧‧‧Reaction chamber

21‧‧‧Insulation cover

22‧‧‧Air intake unit

23‧‧‧ coil

24‧‧‧Base

25‧‧‧ Coverage ring

28‧‧‧Drive unit

26‧‧‧First gas concentration ring

27‧‧‧Second gas concentration ring

W‧‧‧Substrate

ΦD1, ΦD2‧‧‧ inner diameter

Claims (10)

A plasma processing apparatus comprising: a reaction chamber having: an air intake unit for inputting a process gas to the reaction chamber; a base for mounting a substrate to be processed; a gas concentration ring disposed between the air intake unit and the base, comprising an inner annular body and an outer annular body, the outer annular body surrounding the inner annular body and being connected to the inner annular body by at least one spoke Integratedly, a hollow portion between the inner annular body and the outer annular body and a hollow portion inside the inner annular body for passing the process gas and/or its plasma; and a movable second gas concentration ring disposed at An outer peripheral side of the substrate is located between the substrate and the first gas concentration ring; and a driving unit for driving the second gas concentration ring at a first position away from the first gas concentration ring and bonding to the first a vertical movement between a second position of a lower surface of a gas concentration ring; wherein when the second gas concentration ring moves to the second position, it completely shields the hollow between the inner annular body and the outer annular body Partially exposed at the same time The hollow portion inside the inner annular body. The plasma processing apparatus according to claim 1, wherein the inner annular body, the outer annular body and the second gas concentration ring are coaxial rings. The plasma processing apparatus of claim 2, wherein an outer diameter of the second gas concentration ring is larger than an inner diameter of the outer annular body, and an inner diameter of the second gas concentration ring is larger than an inner diameter of the inner annular body The diameter is smaller than the outer diameter of the inner annular body. The plasma processing apparatus of claim 3, wherein the inner diameter of the inner annular body is smaller than the diameter of the substrate, and the inner diameter of the second gas concentration ring is larger than the diameter of the substrate. The plasma processing apparatus of claim 2, wherein the plurality of spokes are evenly distributed along an outer circumference of the inner annular body. The plasma processing apparatus of claim 2, wherein the spoke has a width of 5-30 mm, the inner annular body has a width of 5-30 mm, and the hollow portion between the inner annular body and the outer annular body The width is 10-100mm. The plasma processing apparatus of claim 1, wherein when the second gas concentration ring is moved to the first position, a vertical distance between a lower surface thereof and an upper surface of the substrate is 0-30 mm. The plasma processing apparatus according to claim 1, wherein the material of the first gas concentration ring and the second gas concentration ring is a metal or a dielectric material. The plasma processing apparatus according to claim 1, wherein the spokes have a linear shape, a diagonal shape, or a curved shape. The in-situ plasma etching method of the plasma processing apparatus according to any one of claims 1 to 9, wherein the in-situ plasma etching method comprises performing a deep trench pattern etching process and no pattern etching. The process includes: positioning the second gas concentration ring to the first position; performing the deep trench pattern etching process; positioning the second gas concentration ring to the second position; performing the patternless etching process.