Patent Application
20240404798
The disclosure relates to an apparatus for processing substrates. More specifically the disclosure relates to an apparatus for plasma processing substrates.
In various plasma processing chambers, helium (He) is flowed to a backside of a substrate on an electrostatic chuck (ESC) in order to provide temperature control. Radio frequency (RF) power used for forming a plasma may cause a secondary plasma light-up in the ESC cavities due to high voltage associated with plasma formation. The light-up would promote arcing between any two surfaces with a high electric potential difference between them. Such arcing will cause damage to the ESC.
To achieve the foregoing and in accordance with the purpose of the present disclosure, a spark suppression apparatus for a helium line in an electrostatic chuck in a plasma processing chamber is provided. The spark suppression apparatus comprises a dielectric multilumen plug in the helium line, wherein the dielectric multilumen plug has a plurality of lumens, wherein the plurality of lumens are numbered between 30 to 100,000 lumens and have a width of between 1 micron and 200 microns.
These and other features of the present disclosure will be described in more detail below in the detailed description and in conjunction with the following figures.
The present disclosure is illustrated by way of example, and not by way of limitation, in the figures of the accompanying drawings and in which like reference numerals refer to similar elements and in which:
The present disclosure will now be described in detail with reference to a few embodiments thereof as illustrated in the accompanying drawings. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present disclosure. It will be apparent, however, to one skilled in the art, that the present disclosure may be practiced without some or all of these specific details. In other instances, well-known process steps and/or structures have not been described in detail in order to not unnecessarily obscure the present disclosure.
New semiconductor manufacturing processes require very high RF power plasmas. Increasing RF power causes an increase in RF currents and total voltages applied to the Electrostatic Chuck (ESC-wafer susceptor). At the same time, new plasma etch processes require significantly lower RF frequencies (e.g. 2 MHZ, 400 kHz, or lower) than previously required. Low RF frequencies cause an additional increase in RF voltage applied across ESC ceramic. High voltage applied across ceramic may cause electrical discharge (arcing) between a wafer and a baseplate or ignition (light-up) of heat transfer gas (e.g. He) in the gas supplying holes. Arcing of the ESC usually causes catastrophic destruction of the part accompanied by wafer destruction, possible damage to other chamber components, and manufacturing process interruption. In the case of the heat transfer gas light-up, ESC destruction could be either catastrophic or could slowly develop affecting multiple wafers with semiconductor device damage, being detected only at much later steps of the manufacturing process. In both cases, ESC failure causes significant loss in wafer production and manufacturer's revenue.
For low-voltage applications, it is common to use straight holes in a ceramic plate with ceramic sleeves in baseplates opposing holes in the ceramic plate and preventing direct line of sight. For mid-low voltage applications, ceramic sleeves in baseplates are replaced with porous plugs providing a higher withstand voltage than ceramic sleeves. For mid-voltage applications, porous plugs are inserted in the ceramic plate, in addition to the sleeves in the baseplate. Further breakdown voltage improvement requires new solutions.
An embodiment provides a solution for ESC arcing and He light-up problems by introducing plugs (made of ceramic material, e.g., alumina Al2O3 or aluminum nitride AIN), with small (diameter 0.1-100 micrometers) openings into He holes. The plugs compartmentalize the He hole volume into smaller micro-volumes that limit light-up probability by reducing the number of charged particles' collisions and prevent line of sight between a wafer and metal parts of the chuck below the top ceramic plate while ensuring needed He flow through the holes for the wafer backside cooling.
To facilitate understanding,
On a second side of the porous plug 120 opposite from the first side of the porous plug is a first plenum 124. The porous plug 120 is on a first side of the first plenum 124. The first plenum 124 is formed in the bond layer 112. On a second side of the first plenum 124, opposite from the first side, is a dielectric multilumen plug 128, made of alumina or aluminum nitride with a plurality of small through holes, and the ceramic plate 108. In this embodiment, the dielectric multilumen plug 128 is bonded to the ceramic plate 108. In this example, the dielectric multilumen plug 128 is a dielectric plug that has 50 to 100,000 lumens, where each lumen has a diameter of between 1 micron and 200 microns. The lumens extend from a first side of the dielectric multilumen plug 128, adjacent to the first plenum 124 to a second side of the dielectric multilumen plug 128 opposite from the first side. The ceramic plate 108 has a thickness between 0.5 mm and 3 mm. The dielectric multilumen plug 128 has a height of between 0.1 mm and 2.5 mm. In this embodiment, the lumens are straight round tubes forming a honeycomb cross-section. Since the lumens are straight and extend across the height of the dielectric multilumen plug 128, the lumens have a length of between 0.1 mm and 2.5 mm. In this embodiment, the dielectric multilumen plug 128 has a diameter of 3 to 5 mm. In this embodiment, the dielectric multilumen plug 128 is made of alumina.
A second plenum 132 is on the second side of the dielectric multilumen plug 128. At least one He hole 136 extends from the second plenum 132 to a surface of the ceramic plate 108. In this example, the at least one He hole 136 has a diameter of between 0.02 to 0.3 mm. In this embodiment, other parts of the ESC 100 has other He supply line holes 116, porous plugs 120, first plenums 124, dielectric multilumen plugs 128, second plenums 132, and He holes 136. At the top surface of the ceramic plate 108, the at least one He hole 136 is shown as being wider, since the wider part may be part of a groove or channel connected between a plurality of He holes 136 at the top surface of the ceramic plate 108. The He supply line hole 116 and the at least one He hole 136 form a helium line, wherein the He supply line hole 116 is a first portion of the He line and the at least one He hole 136 is a second portion of the He line. The second plenum has a width 148. The first plenum 124 has a width. The width of the first plenum 124 is about the same as the diameter of the porous portion of the porous plug 120 and the width 148 of the second plenum 132 is about 80% of the dielectric multilumen plug 128 diameter and at least two times the width of the He supply line hole 116.
This embodiment has been found to reduce arcing. As a result, damage to the wafers has been reduced. In addition, the utilization time/coefficient has been improved. Without being bound by theory, it is believed that providing a large number of thin lumens significantly reduces arcing and allows sufficient He flow. In addition, the porous plug 120 increases the path length that electricity must travel in order to reach a conductive material. This further reduces arcing.
On a second side of the porous plug 220 opposite from the first side of the porous plug 220 is a first plenum 224. The porous plug 220 is on a first side of the first plenum 224. The first plenum 224 is formed in the bond layer 212. On a second side of the first plenum 224, opposite from the first side, is a dielectric multilumen plug 228, made of alumina or aluminum nitride with a plurality of small through holes, and the ceramic plate 208. In this embodiment, the dielectric multilumen plug 228 has a solid core 230 at the center. The dielectric multilumen plug 228 is bonded to the ceramic plate 208. In this example, the dielectric multilumen plug 228 has 30 to 100,000 lumens, where each lumen has a diameter of between 1 micron and 200 microns. The lumens extend from a first side of the dielectric multilumen plug 228, adjacent to the first plenum 224 to a second side of the dielectric multilumen plug 228 opposite from the first side.
A second plenum 232 is on the second side of the dielectric multilumen plug 228. At least one He hole 236 extends from the second plenum 232 to a surface of the ceramic plate 208. In this example, the at least one He hole 236 has a diameter of between 0.05 to 0.3 mm. In this embodiment, the solid core 230 has a diameter greater than the diameter of the at least one He hole 236, such as a cluster of He holes (1-6 holes per location). The solid core 230 has a width and is positioned so as to prevent a line of sight path from the He supply line hole 216 to the at least one He hole 236 through the lumens of the dielectric multilumen plug 228. In this embodiment, further reducing the line of sight of the He flow further reduces arcing. The He supply line hole 216 and the at least one He hole 236 form a helium line, wherein the He supply line hole 216 is a first portion of the He line and the at least one He hole 236 is a second portion of the He line.
On a second side of the first plenum 318 is a first side of a first dielectric multilumen plug 320 made of alumina or aluminum nitride with a plurality of small through holes. In this embodiment, the first dielectric multilumen plug 320 has a solid core 322 at the center. The first dielectric multilumen plug 320 is bonded to the base plate 304. In this example, the first dielectric multilumen plug 320 has 30 to 100,000 lumens, where each lumen has a diameter of between 1 micron and 200 microns. The lumens extend from a first side of the first dielectric multilumen plug 320, adjacent to the first plenum 318 to a second side of the first dielectric multilumen plug 320 opposite from the first side. In this example, the first dielectric multilumen plug 320 extends to a top surface of the base plate 304.
On a second side of the first dielectric multilumen plug 320 opposite from the first side of the first dielectric multilumen plug 320 is a second plenum 324. The first dielectric multilumen plug 320 is on a first side of the second plenum 324. The second plenum 324 is formed in the bond layer 312. On a second side of the second plenum 324, opposite from the first side, is a second dielectric multilumen plug 328, made of alumina or aluminum nitride with a plurality of small through holes, and the ceramic plate 308. In this embodiment, the second dielectric multilumen plug 328 has a solid core 330 at the center. The second dielectric multilumen plug 328 is bonded to the ceramic plate 308. In this example, the second dielectric multilumen plug 328 has 30 to 100,000 lumens, where each lumen has a diameter of between 1 micron and 200 microns. The lumens extend from a first side of the second dielectric multilumen plug 328, adjacent to the second plenum 324 to a second side of the second dielectric multilumen plug 328 opposite from the first side.
A third plenum 332 is on the second side of the second dielectric multilumen plug 328. At least one He hole 336 extends from the third plenum 332 to a surface of the ceramic plate 308. In this example, the at least one He hole 336 has a diameter of between 0.05 to 0.3 mm. The solid core 330 of the second dielectric multilumen plug 328 has a diameter greater than the diameter of the at least one He hole 336. The solid core 322 of the first dielectric multilumen plug 320 has a diameter that is greater than the diameter of the solid core 330 of the second dielectric multilumen plug 328 and greater than the diameter of the He supply line hole 316. The solid core 322 of the first dielectric multilumen plug 320 and the solid core 330 of the second dielectric multilumen plug 328 each have a width and are positioned so as to prevent a line of sight path from the He supply line hole 316 to the at least one He hole 336 through the lumens of the first dielectric multilumen plug 320 and the second dielectric multilumen plug 328. The lumens allow for an increased He flow. The He supply line hole 316 and the at least one He hole 336 form a helium line, wherein the He supply line hole 316 is a first portion of the He line and the at least one He hole 336 is a second portion of the He line.
In other embodiments, the solid core 322 of the first dielectric multilumen plug 320 and/or the solid core 330 of the second dielectric multilumen plug 328 may be replaced by multiple lumens. Four combinations may be provided. The widths of the solid cores may also vary to add additional embodiments.
On a second side of the dielectric multilumen plug 420 opposite from the first side of the dielectric multilumen plug 420 is a second plenum 424 located in the bond layer 412. The dielectric multilumen plug 420 is on a first side of the second plenum 424.
On a second side of the second plenum 424, opposite from the first side, is at least one He hole 436 that extends from the second plenum 424 to a surface of the ceramic plate 408. In this example, the at least one He hole 436 has a diameter of between 0.03 to 0.3 mm. The solid core 422 of the dielectric multilumen plug 420 has a width and is positioned so as to prevent a line of sight path from the He supply line hole 416 to the at least one He hole 436, such as a cluster of smaller He holes, through the lumens of the dielectric multilumen plug 420.
This embodiment uses only a single plug. By bonding the dielectric multilumen plug 420 in the base plate 404, the dielectric multilumen plug 420 may be larger, allowing for a single plug. In this embodiment, the ceramic plate 408 has a thickness between 0.5 mm and 1.5 mm. The dielectric multilumen plug 420 has a thickness that is much greater than 1 mm. For example, the dielectric multilumen plug 420 has a thickness or height 421 of between 2 mm to 10 mm. In this example, the solid core 422 has a diameter of 1 to 2 mm. The He supply line hole 416 and the at least one He hole 436 form a helium line, wherein the He supply line hole 416 is a first portion of the He line and the at least one He hole 436 is a second portion of the He line.
On a second side of the first dielectric multilumen plug 520, opposite from the first side of the first dielectric multilumen plug 520, is a second plenum 524. The first dielectric multilumen plug 520 is on a first side of the second plenum 524. The second plenum 524 is formed in the bond layer 512. On a second side of the second plenum 524, opposite from the first side, is a second dielectric multilumen plug 528, made of alumina or aluminum nitride with a plurality of small through holes, and the ceramic plate 508. In this embodiment, the second dielectric multilumen plug 528 has a solid core 530 at the center. The second dielectric multilumen plug 528 is bonded to the ceramic plate 508. In this example, the second dielectric multilumen plug 528 has 30 to 100,000 lumens, where each lumen has a diameter of between 1 micron and 200 microns. The lumens extend from a first side of the second dielectric multilumen plug 528, adjacent to the second plenum 524 to a second side of the second dielectric multilumen plug 528 opposite from the first side. In this embodiment, the second dielectric multilumen plug 528 extends into the second plenum 524. The first side of the second dielectric multilumen plug 528 extends past the surface of the ceramic plate 508 into the layer or region defined by the bond layer 512. In this embodiment, the second dielectric multilumen plug 528 extends into the second plenum 524 to form an overhang of about 50 to 80% of the gap distance, in this specific case: between 0.01 mm to 0.25 mm. In this example, the gap distance is the thickness of the bond layer 512.
A third plenum 532 is on the second side of the second dielectric multilumen plug 528. At least one He hole 536 extends from the third plenum 532 to a surface of the ceramic plate 508. In this example, the at least one He hole 536 has a diameter of between 0.2 to 0.3 mm. The solid core 522 of the first dielectric multilumen plug 520 and the solid core 530 of the second dielectric multilumen plug 528 each have a width and are positioned so as to prevent a line of sight path from the supply line hole 516 to the at least one He hole 536 through the lumens of the first dielectric multilumen plug 520 and the second dielectric multilumen plug 528. The lumens allow for an increased He flow. By extending the second dielectric multilumen plug 528 into the second plenum 524 the height of the second plenum 524 is reduced and arcing is further reduced.
The He passage holes 623 and plurality of lumens 628 are located in a way that there is no direct line of sight from the top of the dielectric multilumen plug 620 to its bottom. E.g., if arranged in circles, diameters of circles by the He passage holes 623 are significantly different from diameters of the circles formed by the plurality of lumens 628. In this embodiment, a multilumen core 640 is attached by bonding or ceramic lamination or any other process, to an outer plug 644 to form the dielectric multilumen plug 620. The plurality of lumens 628 is formed to pass through the multilumen core 640, as shown. The bottom of the multilumen core 640 is spaced apart from a top of a central cavity in the outer plug 644 to provide a space forming the first plenum 624. Such a configuration allows for the dielectric multilumen plug 620 to be more easily formed. The dielectric multilumen plug 620 is T-shaped. In this embodiment, the top of the T-shaped dielectric multilumen plug 620 is bonded to the top of the T-shaped cavity 618 of the base plate 604. A gap 652 is between the bottom of the T-shaped dielectric multilumen plug 620 and the T-shaped cavity 618. In this embodiment, the gap is between 0.1 mm and 1 mm.
Electric charges may travel along the surface of T-shaped dielectric multilumen plug 620 and reach the conductive base plate 604. The gap 652 creates a longer surface length from the at least one He hole 636 through the second plenum 632, the plurality of lumens 628, the first plenum 624, the plurality of He passage holes 623, the central bore 622, and the outer surface of the bottom of the outer plug 644 to the base plate 604. The increase in the surface length reduces arcing. Since top of the T-shaped dielectric multilumen plug 620 is bonded to the top of the T-shaped cavity 618 of the base plate 604 with a gas-tight seal, the gap 652 is gas-tight, so that He passing from the He supply line hole 616 flows through the central bore 622, the plurality of He passage holes 623, the first plenum 624, the lumens 628, the second plenum 632 to the He holes 636. This embodiment has been found to prevent arcing at over 50 kW.
The plurality of lumens 728 is located in a way that there is no direct line of sight from the top of the dielectric multilumen plug 720 to the bottom of the dielectric multilumen plug 720. In this embodiment, a central core 740 is bonded in an outer plug 744 to form the dielectric multilumen plug 720. The lumens 728 are formed to pass through the outer plug 744, as shown. A top surface of the central core 740 is spaced apart from a surface of a central cavity in the outer plug 744 to provide a space forming the first plenum 724. Such a configuration allows for the dielectric multilumen plug 720 to be more easily formed. The dielectric multilumen plug 720 is T-shaped. In this embodiment, the top of the T-shaped dielectric multilumen plug 720 is bonded to the top of the T-shaped cavity 718 of the base plate 704. A gap is between the bottom of the T-shaped dielectric multilumen plug 720 and the T-shaped cavity 718 to reduce arcing, as explained in the previous embodiment. In this embodiment, the gap is between 0.1 mm and 1 mm.
The dielectric multilumen plug 820 is T-shaped. In this embodiment, the top of the T-shaped dielectric multilumen plug 820 is bonded to the top of the T-shaped cavity 818 of the base plate 804. A gap is between the bottom of the T-shaped dielectric multilumen plug 820 and the T-shaped cavity 818 to reduce arcing. In this embodiment, the gap is between 0.1 mm and 1 mm. The lumens 828 are be located away from the cylindrical gap 822 to avoid a direct line of sight from the top of the dielectric multilumen plug 820 to its bottom.
The dielectric multilumen plug 920 is T-shaped. In this embodiment, the top of the T-shaped dielectric multilumen plug 920 is bonded to the top of the T-shaped cavity 918 of the base plate 904. A gap is between the bottom of the T-shaped dielectric multilumen plug 920 and the T-shaped cavity 918 to reduce arcing. In this embodiment, the gap is between 0.1 mm and 1 mm.
Other embodiments may have different combinations of various features of the different embodiments. For example, a dielectric multilumen plug, such as the second dielectric multilumen plug 528 and third plenum 532 of the embodiment shown in
A radio frequency (RF) source 1030 provides RF power to a lower electrode, an upper outer electrode 1016, and an upper inner electrode. In this embodiment, the ESC 1008 is the lower electrode and the gas distribution plate 1006 is the upper inner electrode. In an exemplary embodiment, 400 kilohertz (kHz), 60 megahertz (MHz), 2 MHz, 13.56 MHZ, and/or 27 MHz power sources make up the RF source 1030 and the ESC source 1048. In this embodiment, one generator is provided for each frequency. In other embodiments, the generators may be separate RF sources, or separate RF generators may be connected to different electrodes. Other arrangements of RF sources and electrodes may be used in other embodiments. In other embodiments, an electrode may be an inductive coil.
A controller 1035 is controllably connected to the RF source 1030, the ESC source 1048, an exhaust pump 1020, and the gas source 1010. A high flow liner 1004 is a liner within the etch chamber 1049. The high flow liner 1004 in this embodiment is a C-shroud and confines gas from the gas source and has slots 1002. The high flow liner 1004 allows for a controlled flow of gas to pass from the gas source 1010 to the exhaust pump 1020.
During processing, He gas may be provided from the ESC He source 1050 to the backside of the ESC 1008 to provide heat transfer. The RF source 1030 provides power to form a plasma. The plasma may cause arcing. The arcing could pass towards the He source and damage the ESC 1008. The above embodiment reduces arcing and therefore reduces ESC 1008 damage.
While this disclosure has been described in terms of several embodiments, there are alterations, modifications, permutations, and various substitute equivalents, which fall within the scope of this disclosure. It should also be noted that there are many alternative ways of implementing the methods and apparatuses of the present disclosure. It is therefore intended that the following appended claims be interpreted as including all such alterations, modifications, permutations, and various substitute equivalents as fall within the true spirit and scope of the present disclosure.
This application is a continuation of U.S. application Ser. No. 17/281,183 filed on Mar. 29, 2021, which is a 371 of International Application No. PCT/US2019/058626 filed on Oct. 29, 2019, which claims the benefit of priority of U.S. Application No. 62/754,308, filed on Nov. 1, 2018, which is incorporated herein by reference for all purposes.
| Number | Date | Country | |
|---|---|---|---|
| 62754308 | Nov 2018 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 17281183 | Mar 2021 | US |
| Child | 18800410 | US |
