CN105336561B - Plasma etching apparatus - Google Patents

Abstract

The invention discloses a plasma etching device capable of performing deep groove pattern etching process and patternless etching process in situ, including a reaction chamber, which has an electrostatic chuck for clamping a substrate and a A movable ring-shaped shielding part on the outer peripheral side and above the substrate; a drive unit and a control unit for driving the ring-shaped shielding part to move in the vertical direction. When the deep trench pattern etching process is to be performed, the control unit controls the drive unit to drive the ring-shaped shielding member to be positioned at a first position away from the substrate, and when the pattern-free etching process is to be performed, the control unit controls the drive unit to drive the ring-shaped shielding member. Positioned at a second location adjacent to the substrate. The invention can effectively improve the shape control of high aspect ratio structural pattern etching and the uniformity of patternless etching.

Description

Plasma etching device

technical field

The invention relates to semiconductor processing equipment, in particular to a plasma etching device.

Background technique

With the improvement of integrated circuit integration and the reduction of element line width, the plasma etching (Plasma Etching) process has been widely used. The plasma etching process is to arrange the electrodes in the reaction chamber of the plasma etching device, provide the etching gas as the reaction gas to the reaction chamber, and form the plasma of the reaction gas in the reaction chamber by applying radio frequency on the electrodes. A dry etching process in which etching is performed by radicals, ions, etc. generated by the plasma.

In recent years, the use of plasma etching process to form high aspect ratio structures, such as TSV technology, is receiving more and more attention and research. The formation of a high aspect ratio structure typically uses a patterned etching process to form a patterned photoresist on the wafer surface as a mask layer, and then generates plasma with a suitable reactive gas and applies it to the unmasked layer Protected etch areas, thus etching deep trenches. Generally speaking, after the deep trench is etched, it is also possible to perform a blanket etching process that does not require a mask layer to thin the formed deep trench and finally form a desired depth. High aspect ratio structures. However, in the patternless etching process, due to the difference in etching rate between the edge area and the middle area of the wafer, the etching rate in the edge area is relatively fast, which will cause the etching depth of each high aspect ratio structure in the entire wafer range, The inconsistency between the top feature size and the bottom feature size affects the product yield. However, if the pattern etching and the patternless etching of the high aspect ratio structure are respectively performed in different chambers, the process efficiency will be reduced and the cost will be increased.

In order to solve the above problems, in the prior art, a shadow ring is provided around the wafer to reduce the plasma bombardment in the edge region, thereby improving the etching uniformity during patternless etching. As shown in Figure 1, the plasma etching device comprises a reaction chamber 10, wherein an etching gas is introduced as a reaction gas; the top of the reaction chamber 10 is provided with a reaction gas shower head 11, which includes an upper electrode 15; The bottom of the chamber 10 is provided with an electrostatic chuck 12 for clamping the substrate W to be processed, and a lower electrode 16 opposite to the upper electrode 15 is provided therein. A radio frequency source RF is applied to the lower electrode 16 to form a radio frequency electric field between the upper electrode 15 and the lower electrode 16 to ionize the etching gas to generate plasma. The focus ring 13 is arranged around the substrate W, and its top surface is flush with the top surface of the substrate W, for converging the plasma on the surface of the substrate W. The shielding ring 14 is arranged around the periphery of the focusing ring, and is used to shield or shield a part of the plasma at the periphery of the substrate to reduce the plasma density at the edge of the substrate, thereby reducing the etching rate at the edge of the wafer 30 .

However, although the use of a shadow ring can improve the etching uniformity over the entire substrate in the non-pattern etching process, the shadow ring also affects the plasma density in the edge region at the same time, which will lead to deep trenches in the pattern etching process. Sectional morphology is poorly controlled.

Therefore, it is necessary to propose a plasma etching device capable of simultaneously improving the topography control of high aspect ratio structures and the uniformity of patternless etching.

Contents of the invention

The main purpose of the present invention is to overcome the defects of the prior art, to provide a plasma etching process that can perform pattern etching and patternless etching processes in situ without affecting the etching uniformity and etching morphology of each etching process. erosion device.

In order to achieve the above object, the present invention provides a plasma etching device, which is used to perform deep trench pattern etching process and patternless etching process in situ, which includes a reaction chamber, which has a An electrostatic chuck of the sheet and a movable ring-shaped shielding part, the ring-shaped shielding part is arranged on the outer peripheral side of the substrate and is located above the substrate; the driving unit is used to drive the ring-shaped shielding part in the vertical direction moving up; and a control unit, connected to the driving unit, which controls the driving unit to drive the ring-shaped shielding member to be positioned away from the first first part of the substrate when the deep trench pattern etching process is to be performed. position, controlling the driving unit to drive the ring-shaped shielding member to be positioned at a second position adjacent to the substrate when the non-pattern etching process is to be performed.

Preferably, the reaction chamber further includes a focus ring surrounding the substrate, and the focus ring is located under the ring-shaped shielding member.

Preferably, the reaction chamber further includes a cover ring surrounding the focus ring, the cover ring is located under the ring-shaped shielding member and its upper surface is flush with the upper surface of the focus ring.

Preferably, the annular shielding component is a shielding ring or a gas guiding ring.

Preferably, the inner peripheral surface of the shielding ring is a tapered surface extending radially outward from top to bottom.

Preferably, the cross-sectional shape of the gas guiding ring is rectangular.

Preferably, when the annular shielding member is positioned at the second position, the distance between its lower surface and the upper surface of the substrate is 1-2 mm.

Preferably, when the shielding ring is positioned at the first position, the distance between its lower surface and the upper surface of the substrate is 15-30 mm; when the gas guiding ring is positioned at the first position, the distance between its lower surface and the upper surface of the substrate is The distance between the upper surface of the substrate is 30-60mm.

Preferably, the annular shielding member extends radially inward from the edge of the substrate by -5 mm to 5 mm in the horizontal direction.

Preferably, the upper surfaces of the focus ring and the cover ring protrude from the upper surface of the substrate by 1-2 mm.

Preferably, when the annular shielding member is positioned at the second position, its lower surface is attached to the upper surfaces of the focus ring and the cover ring.

Preferably, the material of the shielding ring is selected from quartz or ceramics, and the material of the gas guiding ring is selected from aluminum.

The present invention also provides an etching method using the above-mentioned plasma etching device. The etching method includes performing a deep trench pattern etching process and a patternless etching process in situ, which includes the following steps: positioning the annular shielding part to the first position; performing the deep trench pattern etching process; positioning the annular shielding part to the second position; and performing the patternless etching process.

Compared with the prior art, the plasma etching device of the present invention can position the liftable ring-shaped shielding parts at different positions in the reaction chamber in the deep groove pattern etching process and the patternless etching process, which can The in-situ execution of the two etching processes is realized, and at the same time, the uniformity of the etching rate and the etching morphology in each etching process are maintained, thereby improving process efficiency and product yield.

Description of drawings

FIG. 1 is a schematic structural view of a plasma etching device in the prior art;

Fig. 2a is a schematic structural diagram of a plasma etching device according to an embodiment of the present invention when performing patternless etching;

Fig. 2b is a schematic structural view of a plasma etching device according to an embodiment of the present invention when etching a structure with a high aspect ratio;

3 is a schematic structural view of a plasma etching device according to another embodiment of the present invention;

FIG. 4 is a schematic flowchart of an etching method using a plasma etching device according to an embodiment of the present invention.

detailed description

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

Figure 2 and Figure 3 show different embodiments of the plasma processing apparatus of the present invention, in the plasma etching apparatus of the present invention, deep trench pattern etching for forming high aspect ratio structures can be performed in-situ process and non-pattern etching process, it should be understood that the plasma etching apparatus is only exemplary, and it may include fewer or more constituent elements, or the arrangement of the constituent elements may be the same or different from that shown in the figure.

Example 1

Please refer to FIG. 2 a and FIG. 2 b , which are schematic structural diagrams of the plasma etching device of this embodiment. The plasma etching device includes a reaction chamber 20, the top of the reaction chamber 20 is provided with a reaction gas shower head 21, the reaction gas shower head 21 includes an upper electrode, and the bottom of the reaction chamber 20 is provided with a The electrostatic chuck 22 of W, the lower electrode opposite to the upper electrode is arranged in the electrostatic chuck 22 . A radio frequency source RF is applied to the lower electrode to form a radio frequency electric field to ionize the etching gas to generate plasma. A liftable annular shielding member 23 is provided on the outer peripheral side of the substrate. As shown in the figure, the annular shielding member 23 is positioned above the surface of the substrate W in a non-contact manner by the support rod 24 . Preferably, three support rods 24 are evenly distributed along the circumferential direction of the annular shielding member 23 , one end of which is fixedly connected to the annular shielding member 23 , and the other end is connected to the driving unit 25 . In this embodiment, the driving unit 25 is arranged at the bottom of the reaction chamber 20, which may include equipment such as motors and cylinders, and is used to lift the support rod 24 and the annular shielding member 23 in the vertical direction so that the annular shielding member 23 approaches Or away from the substrate W. The control unit 26 located outside the reaction chamber is connected to the driving unit 25 , and sends corresponding control signals to the driving unit 25 according to the etching process performed in the reaction chamber to perform the lifting operation of the annular shielding member 23 . Specifically, when the deep groove pattern etching process is to be performed in the reaction chamber 20, the control unit 26 sends a first control signal to make the driving unit 25 drive the connecting rod to drive the ring-shaped shielding member 23 to be positioned to the second position away from the substrate W. A position, and then perform deep trench pattern etching. Since the annular shielding member 23 is far away from the substrate surface, the plasma density near the surface of the substrate W is not easily affected by the annular shielding member 23 during pattern etching, and the cross-section of the deep groove etched in the edge region of the substrate W shape is guaranteed. And when the no-pattern etching process is to be performed in the reaction chamber 20 to adjust the depth of the formed deep groove, the control unit 26 sends a second control signal to make the driving unit 25 drive the connecting rod to drive the annular shielding member 23 to be positioned close to The second position of the substrate W is then etched without patterning. Since the annular shielding part 23 is adjacent to the surface of the substrate, it prevents part of the plasma from contacting the periphery of the substrate, thereby reducing the etching rate at the edge of the substrate, ensuring the uniformity of etching on the entire substrate surface, and improving the high aspect ratio. Uniformity of etch depth, top feature size, and bottom feature size of the structure.

In this embodiment, the annular shielding member 23 is a shielding ring (shadow ring) made of insulating materials such as ceramics or quartz. The lower surface is located 1-2 mm above the top of the substrate, and when the masking ring 23 is raised to the first position by the driving unit 25 for pattern etching, its lower surface is located 15-30 mm above the top of the substrate. The inner peripheral surface of the shielding ring 23 is a tapered surface extending radially outward from top to bottom, thereby forming a protrusion at the top. The distance between the protrusion and the edge of the substrate in the horizontal direction is within the range of ±5mm. When in the patternless etching process, the design of the inclined protrusion properly weakens the plasma reaching the area shielded by the shadow ring 23 , so that the etching speeds of the central area and the edge area of the substrate W are comparable.

Please continue to refer to FIG. 2 a and FIG. 2 b , in this embodiment, the reaction chamber further includes a focusing ring 27 and a covering ring 28 . Both the focus ring 27 and the cover ring 28 are located below the shadow ring 23 . The upper surfaces of the focus ring 27 and the cover ring 28 are flush and slightly protrude from the top surface of the substrate W to be processed, generally by 1-2 mm. Therefore, when the shielding ring 23 is in the second position, it can be directly attached to the upper surfaces of the focus ring 27 and the cover ring 28 . Wherein, the focus ring 27 is arranged on the outer peripheral side of the substrate W to be processed, which is used to provide a relatively closed environment around the substrate W, and confine the plasma to improve the uniformity of the plasma on the surface of the substrate. A cover ring 28 is disposed around the focus ring 27 . Since the top surface of the electrostatic chuck is always covered by the focus ring 27 and the cover ring 28, in the etching process, especially in the deep trench pattern etching process where the shadow ring 23 is raised, the impact on the plasma on the top surface of the electrostatic chuck can be reduced. Exposure to the body or reactive species of the plasma protects the electrostatic chuck from wear and tear. Both the focus ring 27 and the cover ring 28 can be made of insulating materials such as ceramics or quartz. In addition, since the shielding ring 23 is attached to the upper surfaces of the focus ring 27 and the cover ring 28, that is, it is in the second position, so the positioning is more convenient and reliable.

Example 2

FIG. 3 is a schematic structural diagram of another embodiment of the plasma etching device provided by the present invention, which is characterized in that the movable ring-shaped shielding member 23 is a gas guide ring. The gas guide ring 23 is disposed above the surface of the substrate W through the support rod 24 in a non-contact manner. Preferably, three support rods 24 are evenly distributed along the circumference of the gas guiding ring 23 , one end of which is fixedly connected to the gas guiding ring 23 , and the other end is connected to the driving unit 25 . The drive unit 25 receives a signal from the control unit 26 to drive the support rod to drive the gas guide ring 23 to move in the vertical direction. Other components in the plasma etching device, such as the electrostatic chuck 22 , the gas shower head 21 , the control unit 26 and the drive unit 25 , can be configured with reference to the foregoing embodiments.

The gas guide ring 23 itself can guide the reaction gas in the reaction chamber 20 to improve the gas flow distribution. In addition, the gas guide ring in this embodiment can also move in the vertical direction corresponding to different etching processes of deep groove pattern etching and patternless etching. . When the deep trench pattern etching process will be carried out, the control unit 26 sends a first control signal to the drive unit 25, and the drive unit 25 drives the gas guide ring 23 to be positioned at the first position, and the lower surface of the gas guide ring 23 is located at the top of the substrate 30mm to 60mm above. When the patternless etching process is about to be performed, the control unit 26 sends a second control signal to the drive unit 25, and the drive unit 25 drives the gas guide ring 23 to be positioned at the second position, and the lower surface of the gas guide ring is located 1-2 mm above the top of the substrate . The cross-sectional shape of the gas guide ring 23 may be rectangular, and the material is, for example, aluminum. The gas guide ring extends radially inward from the edge of the substrate by -5mm˜5mm in the horizontal direction.

In this embodiment, the reaction chamber 20 of the plasma etching device may also include a focus ring 27 and a cover ring 28 . Both the focus ring 27 and the cover ring 28 are located below the gas guide ring 23 and can still be directly attached to the surfaces of the focus ring 27 and the cover ring 28 when the gas guide ring 23 descends to the second position. The upper surfaces of the focus ring 27 and the cover ring 28 are flush, slightly protruding 1-2 mm from the top surface of the substrate W to be processed. The settings of the focus ring 27 and the cover ring 28 can refer to the foregoing embodiments.

It should be noted that, for the plasma etching device of the present invention, the annular shielding member can adopt various shapes, size parameters, or be made of different materials according to the requirements of substrate etching uniformity in the patternless etching process.

Next, please refer to FIG. 4 , which shows a schematic flow chart of in-situ deep trench pattern etching and patternless etching using the plasma etching device of the present invention, which may specifically include:

Step 41, positioning the annular shielding component to the first position;

In this step, the control unit sends a first control signal to the driving unit, so that the driving unit drives the ring-shaped shielding member to rise to a first position away from the surface of the substrate.

Step 42, performing a deep trench pattern etching process;

In this step, the patterned photoresist is used as an etching hard mask, and a deep trench structure is formed by a conventional plasma etching process.

Step 43, positioning the annular shielding component to the second position;

In this step, the control unit sends a second control signal to the driving unit, so that the driving unit drives the annular shielding member down to a second position adjacent to the surface of the substrate.

Step 44 , performing a non-pattern 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.

To sum up, the plasma etching device of the present invention can realize two different positions in the reaction chamber by positioning the liftable ring-shaped shielding parts in different positions in the deep groove pattern etching process and the patternless etching process. In-situ execution of various etching processes, while the uniformity of etching rate and etching morphology in each etching process can be maintained, improving process efficiency and product yield.

Although the present invention has been disclosed as above with preferred embodiments, the various embodiments described are only examples for convenience of description, and are not intended to limit the present invention. Those skilled in the art can Some changes and modifications are made, and the scope of protection claimed by the present invention should be based on the claims.

Claims (11)

1. A plasma etching device for performing deep groove pattern etching process and no pattern etching process in situ, characterized in that, the plasma etching device comprises: a reaction chamber having: An electrostatic chuck for holding the substrate to be processed; A movable ring-shaped shielding part is arranged on the outer peripheral side of the substrate and is located above the substrate; a driving unit, configured to drive the ring-shaped shielding member to move in the vertical direction; and A control unit connected to the driving unit, which controls the driving unit to drive the ring-shaped shielding member to be positioned at a first position away from the substrate when the deep trench pattern etching process is to be performed. controlling the driving unit to drive the ring-shaped shielding member to be positioned at a second position adjacent to the substrate when performing the patternless etching process; Wherein the annular shielding part is a shielding ring or a gas guiding ring; When the annular shielding member is a shielding ring and the shielding ring is positioned at the first position, the distance between its lower surface and the upper surface of the substrate is 15-30 mm; when the annular shielding member is a gas guide When the ring and the gas guide ring are positioned at the first position, the distance between their lower surface and the upper surface of the substrate is 30-60 mm. 2 . The plasma etching device according to claim 1 , wherein the reaction chamber further comprises a focus ring surrounding the substrate, and the focus ring is located under the annular shielding member. 3 . 3. The plasma etching device according to claim 2, wherein the reaction chamber further comprises a cover ring surrounding the focus ring, the cover ring is located below and above the annular shielding member The surface is flush with the upper surface of the focus ring. 4 . The plasma etching device according to claim 1 , wherein the inner peripheral surface of the shielding ring is a tapered surface extending radially outward from top to bottom. 5 . The plasma etching device according to claim 1 , wherein the cross-sectional shape of the gas guiding ring is a rectangle. 6 . The plasma etching device according to claim 1 , wherein when the annular shielding member is positioned at the second position, the distance between its lower surface and the upper surface of the substrate is 1-2 mm. 7 . The plasma etching device according to claim 6 , wherein the annular shielding member extends radially inward from the edge of the substrate by −5 mm˜5 mm in the horizontal direction. 8 . 8 . The plasma etching device according to claim 3 , wherein the upper surfaces of the focus ring and the cover ring protrude from the upper surface of the substrate by 1-2 mm. 9. The plasma etching device according to claim 8, wherein when the annular shielding member is positioned at the second position, its lower surface is attached to the center of the focus ring and the cover ring. upper surface. 10. The plasma etching device according to claim 1, wherein the material of the shielding ring is selected from quartz or ceramics, and the material of the gas guiding ring is selected from aluminum. 11. An etching method using the plasma etching device according to any one of claims 1 to 10, said etching method comprising performing a deep trench pattern etching process and a patternless etching process in situ, It includes the following steps: positioning the annular shielding member to the first position; performing the deep trench pattern etching process; positioning the annular shielding member to the second position; and performing the patternless etching process.