TWI581328B - Inductively Coupled Plasma Paste Processing Device and Plasma Etch Etching Method - Google Patents

Description

Inductively coupled plasma processing device and plasma etching method

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

The plasma processing apparatus is widely used in various semiconductor manufacturing processes such as a deposition process (such as chemical vapor deposition), an etching process (such as dry etching), and the like. Taking a plasma etching process as an example, FIG. 1 shows a schematic structural view of an inductively coupled plasma etching apparatus of the prior art. The top of the reaction chamber 10 has an insulating cover 11 at the bottom of which is disposed an electrostatic chuck 14 for holding the substrate W to be processed. The air intake unit 12 is disposed below the side wall insulating cover 11 of the reaction chamber 10. 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, and the reaction gas entering the reaction chamber 10 through the air intake unit 12 is ionized to form a plasma to perform plasma treatment on the surface of the substrate W to be processed. A focus ring 15 is provided around the substrate W for concentrating the plasma on the surface of the substrate W. An insulating ring 16 is located below the focus ring 15 for supporting the focus ring 15.

Different etching processes have different requirements on the distribution density of the plasma. For example, in the non-pattern etching process, the etching rate of the edge region and the intermediate region of the substrate is significantly different, and the etching rate of the edge region is fast, which easily causes the entire substrate range. The intrinsic feature size of the device is inconsistent, so the etching rate of the edge region and the intermediate region of the substrate needs to be adjusted; and in the deep trench pattern etching process, it is not necessary to reduce the etching rate of the edge region. Accordingly, it is desirable to provide an improved inductively coupled plasma processing apparatus that can adjust the plasma distribution according to different plasma etching processes.

SUMMARY OF THE INVENTION The main object of the present invention is to overcome the deficiencies of the prior art and to provide an inductively coupled plasma processing apparatus capable of adjusting the density of the plasma and improving the uniformity of the plasma distribution on the surface of the substrate.

To achieve the above object, the present invention provides an inductively coupled plasma processing apparatus including a reaction chamber and a driving unit. The reaction chamber has an air intake unit for inputting a process gas into the reaction chamber; an electrostatic chuck for holding a substrate to be processed; and a focus ring disposed around an outer peripheral side of the substrate, Wherein the focus ring includes a first portion fixedly disposed around an outer circumference of the substrate and a second portion movably disposed on the first portion, wherein a minimum inner diameter of the second portion of the focus ring is greater than Equal to the inner diameter of the first portion of the focus ring. The drive unit is configured to drive a second portion of the focus ring to move vertically between a first position and a second position, wherein when the second portion of the focus ring is positioned at the first position A first portion of the focus ring contacts and cooperates with the first portion to collectively adjust a distribution of process gases and their plasmas adjacent the substrate, the second portion of the focus ring being spaced from the second position when positioned in the second position The upper surface of the first portion of the focus ring is a distance of 5 mm - 15 mm to shield the process gas and its plasma that reach the edge of the substrate.

Preferably, the drive unit further drives the second portion of the focus ring to be positioned in a third position adjacent to the air intake unit when the second portion of the focus ring is positioned in the third position And as an auxiliary gas gathering ring for adjusting the process gas and its plasma distribution in the vicinity of the air intake unit.

Preferably, the reaction chamber further includes a gas accumulation ring disposed horizontally below the air intake unit.

Preferably, when the second portion of the focus ring is in the third position, it is located 0 to 10 mm below the gas accumulation ring.

Preferably, the first portion of the focus ring has a body portion and a protrusion, the protrusion protruding from an upper surface of the body portion, when the second portion of the focus ring is positioned at the first position, The lower surface is in contact with the upper surface of the body portion and the upper surface is flush with the upper surface of the protrusion.

Preferably, the protruding portion of the focus ring protrudes from the upper surface of the substrate by 1 to 3 mm.

Preferably, the first portion of the focus ring protrudes from the upper surface of the substrate by 1 to 3 mm.

Preferably, the maximum inner diameter of the second portion of the focus ring is smaller than the inner diameter of the gas accumulation ring.

Preferably, the inner diameter of the second portion of the focus ring is smaller than the inner diameter of the gas accumulation ring.

Preferably, the cross-sectional shape of the second portion of the focus ring is rectangular or trapezoidal.

Preferably, the second portion of the focus ring has a rectangular cross-sectional shape with a width of 1/4 to 2/3 of the radius of the reaction chamber.

Preferably, the reaction chamber further includes an insulating ring surrounding an outer peripheral side of the electrostatic chuck, and a first portion of the focus ring is disposed over the insulating ring and covers an upper surface of the insulating ring.

Preferably, the material of the focus ring is ceramic or quartz, and the material of the gas accumulation ring is aluminum alloy.

The present invention also provides a plasma etching method using the above inductively coupled 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: focusing the focus ring Positioning the second portion to the first position in contact with the first portion of the focus ring; performing the deep trench pattern etching process; positioning the second portion of the focus ring to the second position; A no-pattern etching process is described.

Compared with the prior art, the plasma processing apparatus of the present invention utilizes the second portion of the liftable focus ring to be positioned at different positions within the reaction chamber, respectively, and when the first portion of the focus ring is in contact with the first portion becomes a The integral focus ring adjusts the plasma sheath and gas distribution in the vicinity of the substrate, and masks or shields a portion of the plasma at the periphery of the substrate when the substrate is located 5 to 15 mm above the first portion to make the edge of the substrate partially plasma. The reduced density, reduced etch rate of the edge of the substrate, can also be used as another gas accumulation ring to adjust the gas distribution and plasma density within the chamber when located above the chamber.

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. It is a matter of course that the invention is not limited to the specific embodiment, and that general substitutions well known to those skilled in the art are also encompassed within the scope of the invention.

2 and 3 illustrate different embodiments of the inductively coupled plasma processing apparatus of the present invention, it being understood that the inductively coupled plasma processing apparatus is merely exemplary and may include fewer or more constituent elements, or The arrangement of the constituent elements may be the same as or different from that shown in the figures.

Example 1

As shown in FIG. 2, the inductively coupled plasma processing apparatus includes a reaction chamber 20 having an insulating cover 21 above it, and the insulating cover 21 is typically a ceramic dielectric material. An air intake unit 22 for introducing a process gas into the interior of the reaction chamber 20 is provided at a side wall of the reaction chamber near the top. An electrostatic chuck 23 for holding 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 a plasma is generated to perform etching or the like on the substrate W. 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 focus ring is provided around the outer peripheral side of the substrate W. As shown, the focus ring includes two portions 25a and 25b. The first portion 25a is fixedly disposed around the outer periphery of the substrate W, and has an inner diameter larger than the outer diameter of the substrate W to provide a relatively closed environment around the substrate W while preventing shadowing of the edge region of the substrate W; The portion 25a is movably disposed above the first portion 25a and may have a rectangular or trapezoidal cross-sectional shape, but the minimum inner diameter is larger than the inner diameter of the first portion 25a. Therefore, the minimum horizontal distance from the periphery of the second portion 25b to the substrate W is greater than the horizontal distance from the inner periphery of the first portion 25a to the substrate W. When the cross-sectional shape of the second portion 25b is a rectangle, the width of the rectangle is about 1/4 to 2/3 of the radius of the chamber 20, and a better plasma adjustment effect can be achieved. The first portion 25a and the second portion 25b are each made of an insulating material such as ceramic. The second portion 25b is positioned over the surface of the first portion 25a by a support rod 26. The support rods 26 are preferably evenly distributed in a plurality of directions, such as three, along the circumferential direction of the second portion 25b of the focus ring. One end of each of the support rods 26 is fixedly coupled to the second portion 25b of the focus ring, and the other end is coupled to the drive unit 27. In this embodiment, the driving unit 27 is disposed outside the reaction chamber 20, and may include a motor, a cylinder, and the like for lifting the support rod 26 and the second portion 25b of the focus ring in a vertical direction to make the focus ring The two portions 25b are close to or away from the substrate W. Specifically, the driving unit 27 drives the second portion 25b of the focus ring to move between the first position and the second position in the vertical direction, and positions the second portion 25b of the focus ring to the first position or the second as needed. position. When the second portion 25b of the focus ring is positioned in the first position, it contacts the first portion 25a of the focus ring, which cooperates with the first portion 25a to adjust the distribution of the process gas and its plasma adjacent the substrate. Specifically, the two portions of the focus ring form an integral focus ring and serve as the primary plasma agglomeration with the first portion 25a of the focus ring, as indicated by the solid arrows in the figure, and the second portion 25b is The shielding effect of the edge of the sheet is very small or even not shielding, so when the second portion 25b of the focus ring is positioned at the first position, deep trench plasma etching can be performed, and the density of the plasma near the surface of the substrate W is not easily affected. The effect of the second portion 25b of the focus ring ensures that the profile of the deep trench etched in the edge region of the substrate W is ensured. Preferably, as shown, the first portion 25a of the focus ring has a main body portion and a projection portion 251 which protrudes from the upper surface of the main body portion in a narrow annular structure around the outer peripheral side of the substrate W. The focus ring second portion 25b is movably disposed on the outer peripheral side of the protruding portion 251 of the first portion 25a, and when it is positioned at the first position, the lower surface thereof is in contact with the upper surface of the main body portion of the first portion 25a of the focus ring, thereby The two portions 25b are embedded in the first portion 25a, the portion of which protrudes from the first portion 25a is less, and the shielding effect on the edge edge plasma is also smaller. More preferably, the upper surface of the second portion 25b is flush with the upper surface of the protrusion 251, so that the second portion 25b of the focus ring does not generate the plasma density at the edge region of the substrate W during the deep trench etching process. influences. When the second portion 25b of the focus ring is positioned at the second position, it is 5 to 15 mm away from the upper surface of the first portion 25a of the focus ring (the top surface of the protrusion 251 in this embodiment), which can effectively block the freedom in the reaction chamber. The etching of the edge of the substrate serves to shield the plasma from contacting the periphery of the substrate W, as indicated by the dashed arrow in FIG. At this time, the second portion 25b of the focus ring can reduce the process gas and the plasma distribution at the edge of the substrate, and reduce the etching rate at the edge, thereby ensuring the etching uniformity of the entire substrate surface. Therefore, when the focus ring When the second portion 25b is positioned at the second position, a patternless etching process can be performed. Optionally, in this embodiment, in order to prevent the substrate W from flying out during the plasma processing, the protruding portion 251 protrudes from the upper surface of the substrate by 1 to 3 mm to block the substrate W from flying out. Further, as in the embodiment 2 shown in Fig. 3, the first portion 25a of the focus ring may not be provided with a projection but the entire upper surface protrudes from the upper surface of the substrate W by 1 to 3 mm to prevent the substrate from flying out.

In addition, the reaction chamber 20 further includes a gas accumulation ring 28 disposed horizontally below the air intake unit 22, and the process gas and its plasma distribution in the vicinity of the air intake unit 22 can be restrained according to the inner diameter thereof. The gas agglomeration ring 28 can be made of an aluminum alloy material. Also included within the reaction chamber 20 is an insulating ring 29 that surrounds the electrostatic chuck 24. The first portion 25a of the focus ring is fixedly disposed over the insulating ring 29 and covers the upper surface of the insulating ring 29, whereby the insulating ring 29 functions to fix and support the first portion 25a of the focus ring. The cross-sectional shape of the insulating ring 29 may be L-shaped or rectangular, and the invention is not limited thereto. The inner side wall of the insulating ring 29 and the outer side wall of the electrostatic chuck 24 are as close as possible to prevent the plasma from hitting the surface of the electrostatic chuck 24, protecting the electrostatic chuck 24 from loss. The insulating ring 29 may be formed of an insulating material such as ceramic or quartz.

Example 2

3 is a schematic structural view of another embodiment of an inductively coupled plasma processing apparatus according to the present invention. In this embodiment, the drive unit 27 can also drive the second portion 25b of the focus ring to move to the third position. When the second portion 25b of the focus ring is positioned at the third position, it is adjacent to the intake unit 22 and serves as an auxiliary gas accumulating ring to adjust the process gas and its plasma distribution in the vicinity of the intake unit 22 by the inner diameter thereof. . Of course, at this time, the first portion 25a of the focus ring still converges on the plasma near the substrate W. In the present embodiment, the reaction chamber 20 also includes a gas accumulation ring 28 disposed horizontally below the inlet unit 22, the inner diameter preferably being greater than the maximum inner diameter of the second portion 25b of the focus ring. When the drive unit 27 drives the second portion 25b of the focus ring to be positioned at the third position, the second portion 25b is positioned as an auxiliary gas accumulation ring below the gas accumulation ring 28, with a smaller inner diameter for the electricity passing through the gas accumulation ring 28. The slurry is constrained to further adjust the plasma concentration as indicated by the dotted line arrow in FIG. Therefore, according to the embodiment, when the process gas and the plasma distribution entering the chamber need to be adjusted due to the process requirements, the second portion 25b of the focus ring can be raised to the third position without replacement. The gas agglomeration ring 28 increases process efficiency. Further, since the cross-sectional shape of the second portion 25b of the focus ring may be rectangular or trapezoidal, it is also possible to guide the process gas and its plasma to be introduced in different diffusion directions. In addition, the inductively coupled plasma processing apparatus of the present embodiment may also include an insulating ring 29, and the arrangement thereof may be referred to the foregoing embodiment, and details are not described herein again.

Example 3

The inductively coupled plasma processing apparatus of the present invention is particularly suitable for performing deep trench pattern etching processes and patternless etching processes in situ. This embodiment will explain the steps of applying the above-described in-situ etching process to the plasma processing apparatus.

As shown in FIG. 4, the steps of performing deep trench pattern etching and patternless etching in situ include:

S1: positioning the second portion of the focus ring to the first position to be in contact with the first portion of the focus ring;

S2: performing a deep trench pattern etching process;

S3: positioning the second portion of the focus ring to the second position;

S4: Perform a patternless etching process.

When the deep trench pattern etching is performed, since the second portion of the focus ring is positioned at the first position, the distribution of the plasma at the edge of the substrate is not affected, and the profile of the deep trench etched in the edge region of the substrate W can be Guarantee. Thereafter, when a patternless etch is performed to adjust the depth of the formed deep trench, the second portion of the focus ring is positioned at the second position to reduce the etch rate at the edge of the substrate, ensuring etch uniformity across the surface of the substrate.

In summary, the plasma processing apparatus of the present invention can be configured by positioning the focus ring as a fixed first portion and a second portion that can be lifted and lowered, and positioning the second portion in different positions in the reaction chamber, respectively. The plasma density distribution in the vicinity of the substrate is adjusted to meet the uniformity of the etching rate and the etching morphology, thereby improving process efficiency and product yield.

The present invention has been described in the above preferred embodiments, and the present invention is not intended to limit the scope of the present invention, and is not intended to limit the scope of the invention. A number of changes and refinements may be made, and the scope of protection claimed by the present invention shall be as described in the scope of the patent application.

10‧‧‧Reaction chamber
11‧‧‧Insulation cover
12‧‧‧Air intake unit
13‧‧‧Inductively coupled coil
14‧‧‧Electrical chuck
15‧‧‧ Focus ring
16‧‧‧Insulation ring
20‧‧‧Reaction chamber
21‧‧‧Insulation cover
22‧‧‧Air intake unit
23‧‧‧Electrical chuck
23‧‧‧Inductively coupled coil
24‧‧‧Electrical chuck
251‧‧‧Protruding
25a‧‧‧Part 1
25b‧‧‧Part II
26‧‧‧Support rod
27‧‧‧Drive unit
28‧‧‧Gathering ring
29‧‧‧Insulation ring
W‧‧‧ substrates

1 is a schematic structural view of an inductively coupled plasma etching apparatus in a prior art; FIG. 2 is a schematic structural view of an inductively coupled plasma processing apparatus according to an embodiment of the present invention; [FIG. 3] A schematic structural view of an inductively coupled plasma processing apparatus of an embodiment; [Fig. 4] is a flow chart showing an etching method of an inductively coupled plasma processing apparatus according to an embodiment of the present invention.

20‧‧‧Reaction chamber

21‧‧‧Insulation cover

22‧‧‧Air intake unit

23‧‧‧Electrical chuck

23‧‧‧Inductively coupled coil

24‧‧‧Electrical chuck

251‧‧‧Protruding

25a‧‧‧Part 1

25b‧‧‧Part II

26‧‧‧Support rod

27‧‧‧Drive unit

28‧‧‧Gathering ring

29‧‧‧Insulation ring

W‧‧‧ substrates

Claims (13)

An inductively coupled plasma processing apparatus comprising: a reaction chamber having: an air intake unit for inputting a process gas into the reaction chamber; an electrostatic chuck for holding a substrate to be processed; a focus ring disposed on an outer peripheral side of the substrate, the focus ring including a first portion fixedly disposed around an outer circumference of the substrate; and a second portion movably disposed on the first portion; wherein a minimum inner diameter of the second portion of the focus ring is greater than or equal to an inner diameter of the first portion of the focus ring; and a drive unit for driving the second portion of the focus ring to move vertically between the first position and the second position, Wherein when the second portion of the focus ring is positioned in the first position, it contacts the first portion of the focus ring and cooperates with the first portion to collectively adjust the distribution of process gases and their plasmas in the vicinity of the substrate Providing a distance of 5 mm to 15 mm from the upper surface of the first portion of the focus ring to shield the process gas reaching the edge of the substrate and its electricity when the second portion of the focus ring is positioned at the second position Body. The inductively coupled plasma processing apparatus of claim 1, wherein the driving unit further drives the second portion of the focus ring to be positioned in a third position, and when the second portion of the focus ring is positioned at the The third position is adjacent to the air intake unit and serves as an auxiliary gas accumulation ring for adjusting the process gas and its plasma distribution in the vicinity of the air intake unit. The inductively coupled plasma processing apparatus of claim 1, wherein the reaction chamber further comprises a gas accumulation ring disposed horizontally below the air intake unit. The inductively coupled plasma processing apparatus of claim 2, wherein when the second portion of the focus ring is in the third position, it is located 0 to 10 mm below the gas accumulation ring. The inductively coupled plasma processing apparatus of claim 1, wherein the first portion of the focus ring has a body portion and a protrusion, the protrusion protruding from an upper surface of the body portion when the focus ring When the second portion is positioned in the first position, its lower surface is in contact with the upper surface of the body portion and the upper surface is flush with the upper surface of the protrusion. The inductively coupled plasma processing apparatus according to claim 5, wherein the protrusion protrudes from the upper surface of the substrate by 1 to 3 mm. The inductively coupled plasma processing apparatus according to claim 1, wherein the first portion of the focus ring protrudes from the upper surface of the substrate by 1 to 3 mm. The inductively coupled plasma processing apparatus of claim 3, wherein a maximum inner diameter of the second portion of the focus ring is smaller than an inner diameter of the gas accumulation ring. The inductively coupled plasma processing apparatus according to claim 1, wherein the second portion of the focus ring has a rectangular or trapezoidal cross-sectional shape. The inductively coupled plasma processing apparatus according to claim 7, wherein the second portion of the focus ring has a rectangular cross section having a width of 1/4 to 2/3 of a radius of the reaction chamber. The inductively coupled plasma processing apparatus according to claim 1, wherein the reaction chamber further includes an insulating ring surrounding an outer peripheral side of the electrostatic chuck, and a first portion of the focus ring is disposed above the insulating ring And covering the upper surface of the insulating ring. The inductively coupled plasma processing apparatus according to claim 3, wherein the material of the focus ring is ceramic or quartz, and the material of the gas accumulation ring is an aluminum alloy. A plasma etching method for an inductively coupled plasma processing apparatus according to any one of claims 1 to 12, which comprises performing a deep trench pattern etching process and a patternless etching process in situ, including: The second portion of the focus ring is positioned to the first position in contact with the first portion of the focus ring; Performing the deep trench pattern etching process; positioning the second portion of the focus ring to the second position; performing the patternless etching process.