TW201508806A - Plasma processing device - Google Patents

Abstract

The present invention provides a plasma processing device, including a reaction chamber which is provided with an upper electrode and a lower electrode parallel to each other. The lower electrode is disposed in a platform which includes an electrostatic chuck. A substrate is disposed on the electrostatic chuck for processing. The present invention is characterized that the plasma processing device further includes: an annular insulating body surrounding the electrostatic chuck and/or an upper area of the electrostatic chuck; a first electrode embedded in the annular insulating body; a first radio frequency (RF) power source connected to the lower electrode via a first RF matcher for the RF power to form a vertical RF electric field between the upper electrode and the lower electrode so as to generate plasma; and a pulsed direct current power connected to the first electrode. The present invention is capable of improving the uniformity of the substrate manufacturing process.

Description

Plasma processing device

The present invention relates to the field of semiconductor fabrication, and more particularly to a plasma processing apparatus.

In recent years, with the development of semiconductor manufacturing processes, the integration and performance requirements of components have become higher and higher, and Plasma Technology has been widely used. Plasma technology uses a radio frequency electric field to accelerate electrons by introducing a reaction gas into a reaction chamber of a plasma processing apparatus and introducing a flow of electrons. The reaction gas collides with the reaction gas to ionize the plasma, and the generated plasma can be used. In various semiconductor manufacturing processes, such as deposition processes (such as chemical vapor deposition), etching processes (such as dry etching), and the like.

Plasma processing processes often employ capacitively coupled plasma processing devices to generate plasma. FIG. 1 is a schematic view showing the structure of a capacitive coupling type plasma processing apparatus. As shown in FIG. 1, a pair of flat upper electrodes 2 and lower electrodes 3 are arranged in parallel in the reaction chamber 1 of the plasma processing apparatus. The upper electrode is disposed in the reaction gas nozzle, and the lower electrode is disposed in the electrostatic chuck 4. The substrate 5 to be processed is placed on the electrostatic chuck 4. By applying radio frequency in the parallel plate-type lower electrode 3, the upper electrode 2 is grounded, so that a vertical radio frequency electric field is formed between the upper electrode 2 and the lower electrode 3, and electrons accelerated by the radio frequency electric field are ionized and collided with molecules of the reaction gas. , ionizing the reaction gas to generate a plasma.

However, in practical applications, the uniformity of the plasma density generated by the capacitive coupling type plasma processing apparatus is not ideal. Due to the structural characteristics of capacitive coupling, the electric field strengths of the intermediate and edge regions of the reaction chamber are different, and the density of the generated plasma has a characteristic distribution of the intermediate region higher than the edge region, and the rate of plasma treatment of the substrate In connection with this plasma density, the plasma processing process may eventually be uneven: for example, the substrate is etched or processed at a high rate, the edge is etched, or the processing rate is slow. This has a great impact on the process control and yield of semiconductor device manufacturing. Therefore, how to improve the uniformity of the plasma density in the plasma processing apparatus is a technical problem that is urgently needed to be solved by those skilled in the art.

To solve this problem, one of the prior art methods is to provide a closed conductive ring connecting the second RF power source around the electrostatic chuck, and form a ring-shaped second electric field above the closed conductive ring through the second RF power source, and then Adjusting the parameters of the second RF power source such that the second electric field of the ring and the electric field above the lower electrode are superimposed on each other to improve the electric field distribution in the edge region of the electrostatic chuck, and the plasma density of the central region and the edge region of the substrate to be processed Has good consistency and uniformity.

In view of the above, the present invention proposes a plasma processing apparatus.

The technical means for solving the problems of the prior art is to provide a plasma processing apparatus, the plasma processing apparatus comprising a reaction chamber, wherein the reaction chamber is provided with upper and lower electrodes parallel to each other. The lower electrode is disposed in the base, the base includes an electrostatic chuck, and the substrate is disposed on the electrostatic chuck to perform the process, wherein the plasma processing apparatus further comprises: an annular insulator surrounding the An electrostatic chuck and/or an upper region of the electrostatic chuck; a first electrode embedded in the annular insulator; a first RF power source connected to the lower electrode by a first RF matching device, And a radio frequency electric field for forming a vertical direction between the upper electrode and the lower electrode to generate a plasma; and a pulsed direct current power source connected to the first electrode.

Further, an RF filter is further connected between the first electrode and the pulsed DC power source.

Further, the pulsed DC power source is low frequency.

Further, the frequency of the pulsed DC power source is 100 khz to 350 khz.

Further, the reaction chamber further includes a focus ring surrounding the substrate, the insulating ring is located below the focus ring and surrounds the electrostatic chuck; The annular insulator is embedded in the insulating ring.

Further, the reaction chamber further includes a plasma confinement assembly including a plurality of rings stacked in a vertical direction and spaced apart from each other, the plasma confinement assembly surrounding an area above the electrostatic chuck; At least one of the plasma confinement elements is the annular insulator.

Further, the material of the annular insulator is selected from quartz or ceramic.

Further, the first electrode is made of metal.

Further, the first electrode is an open metal ring electrode.

Further, the open metal ring electrode is formed by winding one or two turns of the wire.

Compared with the prior art, the plasma processing apparatus of the present invention has the beneficial effects that the present invention compensates for the edge region of the substrate by providing a first electrode around or around the substrate to generate a complementary electric field in the vertical direction in the reaction chamber. The plasma density, which in turn makes the plasma processing process uniform. In addition, the present invention adopts a pulsed DC source control method without a matching network, and has a simple structure and a stable system.

The specific embodiments of the present invention will be further described by the following examples and the accompanying drawings.

Specific embodiments of the present invention will be described below with reference to the accompanying drawings.

It should be understood that the plasma processing apparatus in the present invention may be a device such as plasma etching, plasma physical vapor deposition, plasma chemical vapor deposition, plasma surface cleaning, etc., and the plasma processing apparatus is merely exemplary, and Fewer or more constituent elements may be included, or the arrangement of the constituent elements may be the same or different from that shown in the figures.

Referring to Figure 2, there is shown a schematic view of the structure of the plasma processing chamber of the present embodiment. The plasma processing apparatus includes a reaction chamber 10 into which a reaction gas is introduced; a reaction gas head is disposed at the top of the reaction chamber 10, and the reaction gas head includes a flat upper electrode 21, the upper electrode 21 is grounded; and the bottom of the reaction chamber 10 An electrostatic chuck 11 for holding the substrate 30 is provided, which may be a semiconductor substrate to be etched or processed or a glass plate to be processed into a flat panel display. A flat-plate lower electrode 22 parallel to the upper electrode 21 is provided in the electrostatic chuck 11. The lower electrode 22 is connected to the first RF source 40 through the first RF matcher 41. The first RF source 40 is applied to the lower electrode 22 such that a vertical RF electric field is formed between the upper electrode 21 and the lower electrode 22. The electrons accelerated by the RF electric field are ionized and collided with the molecules of the reactive gas to ionize the reaction gas to generate a plasma. body. In order to improve the plasma density distribution, the present invention provides a first electrode, typically an open metal ring electrode 23, around or around the electrostatic chuck 11. In order to prevent the open metal ring electrode 23 from being exposed to the plasma environment, the open metal ring electrode 23 is embedded in the annular insulator. The material of the annular insulator is, for example, an insulating material such as ceramic or quartz. The annular insulator may surround the area above the electrostatic chuck 11 or the electrostatic chuck 11 or surround the electrostatic chuck 11 and its upper area. The electrostatic chuck 11 and the open metal ring electrode 23 are disposed at the same center. Further, the open metal ring electrode 23 is formed by winding a wire, and preferably, the open metal ring electrode is wound one or two turns. A low frequency DC pulse is applied to the open metal ring electrode 23, and a low frequency DC pulse is generated by a pulsed DC power source 42 applied to the metal ring. The pulsed DC power source 42 causes an additional electric field in the vertical direction of the substrate edge region, which can supplement the electric field strength of the edge region of the substrate, thereby increasing the etching rate of the edge region of the substrate, so that the intermediate region of the substrate The difference in the etching rate of the edge regions is within an acceptable range, so that the uniformity of the substrate can be improved.

The reaction chamber also includes a focus ring 12 and an insulating ring 13. A focus ring 12 is disposed about the substrate 30 to be treated to provide a relatively closed environment around the substrate 30, confining the plasma to improve the uniformity of the plasma on the surface of the substrate 30. The insulating ring 13 is located below the focus ring and surrounds the electrostatic chuck 11 to function to secure and support the focus ring 12. The insulating ring 13 may be formed of an insulating material such as ceramic or quartz. In the present embodiment, the insulating ring 13 is used as an annular insulator, and the open metal ring electrode 23 is horizontally embedded in the insulating ring 13, whereby an induced electric field in the horizontal direction can be formed in the edge region of the electrostatic chuck, thereby compensating the substrate. Plasma density in the edge region.

3 is a schematic structural view showing another embodiment of a plasma processing apparatus according to the present invention, which shows a variation of the above embodiment, and the difference between this embodiment and the above embodiment is that in this embodiment The reaction chamber includes a plasma confinement assembly 14 comprising a plurality of rings 14a stacked in a vertical direction and spaced apart from each other, the rings 14a surrounding the upper region of the electrostatic chuck, that is, the upper electrode 21 and the lower electrode 22 The region between which is considered to be a reaction region P in which plasma is formed and the substrate 30 is treated. There is a gap between the adjacent rings 14a. When the substrate 30 is subjected to plasma treatment, the treated reaction gas can be discharged out of the reaction region P through the slit, and the plasma can be confined in the reaction region P. The ring 14a can be made of various materials that are resistant to plasma corrosion, such as quartz or ceramic. In order to simultaneously utilize the design of the present invention, at least one ring or rings 14a of the plasma confinement element 14 may be designed as the aforementioned annular insulator with an open metal ring electrode 23 embedded therein, wherein the open metal ring electrode 23 is fused with a radio frequency current. Similar to the principle of operation in Embodiment 1, the open metal ring electrode 23 is formed by winding a wire, preferably one or two turns, in which a circulating RF current generates an alternating magnetic field and further produces a circumference along the circumference of the metal ring. The compensation electric field in the horizontal direction. The compensation electric field compensates for the electric field intensity near the open metal ring electrode 23, that is, the edge region of the reaction region P, so that the plasma density of the edge region of the reaction region P increases, thereby increasing the plasma density distribution at different positions above the substrate 30. Uniformity. The low frequency DC pulse in the open metal ring electrode 23 is also generated by a pulsed DC power source 42 applied thereto.

Further, an RF filter 43 is further connected between the first electrode 23 and the pulsed DC power source 42. The RF filter 43 is used to prevent radio frequency energy of the first RF source 40 from leaking to the pulsed DC power source 42, thereby generating crosstalk.

Further, the pulsed DC power source 42 is low frequency. Typically, the pulsed DC power source 42 has a frequency of 100 khz to 350 khz.

Further, the reaction chamber further includes a focus ring 12 surrounding the substrate 30, and an insulating ring 13 located below the focus ring 12 and surrounding the electrostatic chuck 11 The insulating ring 13 is the annular insulator, and the first electrode is embedded in the insulating ring. The material of the annular insulator is selected from quartz or ceramic.

In summary, the plasma processing apparatus of the present invention generates a vertical induced electric field in an edge region of the reaction chamber by providing an open metal ring electrode having a pulsed direct current in a region surrounding the substrate or the substrate. Compensating for the uneven distribution of the RF electric field between the upper and lower electrodes in the central and edge regions of the reaction chamber, so that the plasma density of the corresponding central and edge regions of the substrate is evenly distributed, thereby making the plasma on the substrate The processing is more uniform.

In addition, the present invention utilizes a DC pulse source to modulate the thickness of the wafer edge shell. Compared with the modulation of the shell layer by the RF power source, the advantage is that the RF power source must be equipped with a corresponding automatic matching network, the structure is complicated, the cost is expensive, and the stability is difficult to control. The pulsed DC source control mode does not require a matching network, and the structure is simple and the system is stable.

Although the present invention has been described in detail by the preferred embodiments thereof, it should be understood that the description Various modifications and alterations of the present invention will be apparent to those skilled in the art. Therefore, the scope of the invention should be defined by the appended claims.

The above description is only for the preferred embodiment of the present invention, and those skilled in the art can make other improvements according to the above description, but these changes still belong to the inventive spirit of the present invention and the patents defined below. In the scope.

[study]
10‧‧‧Reaction chamber
11‧‧‧Electrical chuck
12‧‧‧ Focus ring
13‧‧‧Insulation ring
14‧‧‧Ion body constrained components
14a‧‧‧ Ring
21‧‧‧Upper electrode
22‧‧‧ lower electrode
23‧‧‧Open metal ring electrode
30‧‧‧Substrate
40‧‧‧First RF source
41‧‧‧First RF Matcher
42‧‧‧ pulsed DC power supply
43‧‧‧RF filter
P‧‧‧Reaction area
RD
[study]
1‧‧‧reaction chamber
2‧‧‧Upper electrode
3‧‧‧ lower electrode
4‧‧‧Electrical chuck
5‧‧‧Substrate

1 is a schematic structural view of a plasma processing apparatus of the prior art; FIG. 2 is a schematic structural view of a plasma processing apparatus according to an embodiment of the present invention; and FIG. 3 is a plasma processing apparatus according to another embodiment of the present invention. Schematic.

10‧‧‧Reaction chamber

11‧‧‧Electrical chuck

12‧‧‧ Focus ring

13‧‧‧Insulation ring

21‧‧‧Upper electrode

22‧‧‧ lower electrode

23‧‧‧Open metal ring electrode

30‧‧‧Substrate

40‧‧‧First RF source

41‧‧‧First RF Matcher

42‧‧‧ pulsed DC power supply

43‧‧‧RF filter

Claims (10)

A plasma processing apparatus comprising a reaction chamber, wherein the reaction chamber is provided with upper and lower electrodes parallel to each other, the lower electrode is disposed in the base, the base includes an electrostatic chuck, and the substrate is disposed on the substrate The process is performed on the electrostatic chuck, wherein the plasma processing apparatus further comprises: an annular insulator surrounding the electrostatic chuck and/or an upper region of the electrostatic chuck; a first electrode; Embedded in the annular insulator; a first RF power source connected to the lower electrode through a first RF matching device for providing RF power to form a vertical direction RF between the upper electrode and the lower electrode An electric field to generate a plasma; and a pulsed DC power source coupled to the first electrode. The plasma processing apparatus of claim 1, wherein an RF filter is further coupled between the first electrode and the pulsed DC power source. The plasma processing apparatus of claim 1, wherein the pulsed direct current power source is low frequency. The plasma processing apparatus of claim 3, wherein the pulsed direct current power source has a frequency of 100 khz to 350 khz. The plasma processing apparatus of claim 1, wherein the reaction chamber further comprises a focus ring surrounding the substrate, the focus ring being located below the focus ring and surrounding the An electrostatic chuck; the insulating ring is the annular insulator, and the first electrode is embedded in the insulating ring. The plasma processing apparatus of claim 1, wherein the reaction chamber further comprises a plasma confinement assembly comprising a plurality of rings stacked in a vertical direction and spaced apart from each other in parallel, the plasma confinement assembly surrounding An area above the electrostatic chuck; at least one of the plasma confinement elements is the annular insulator. The plasma processing apparatus of claim 1, wherein the material of the annular insulator is selected from the group consisting of quartz or ceramic. The plasma processing apparatus of claim 1, wherein the first electrode is made of metal. The plasma processing apparatus of claim 8, wherein the first electrode is an open metal ring electrode. The plasma processing apparatus according to claim 9, wherein the open metal ring is formed by winding a wire one or two turns.