JP4283366B2 - Plasma processing equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a plasma processing apparatus for performing a predetermined process on the surface of a substrate with plasma.
[0002]
[Prior art]
Applying a predetermined treatment to the surface of a substrate with plasma is actively performed in the manufacture of various semiconductor devices such as DRAM (Dynamic Random Access Memory) and liquid crystal displays. For example, when a fine circuit is formed on the surface of a substrate, plasma etching is performed in which the substrate is etched by plasma in an etching process using a resist pattern as a mask. Further, in the production of various conductive films and insulating films, a plasma CVD (chemical vapor deposition) technique using a gas phase reaction in plasma has been put into practical use.
[0003]
FIG. 9 is a front view showing a schematic configuration of a plasma etching apparatus as an example of a conventional plasma processing apparatus. The apparatus shown in FIG. 9 includes a processing chamber 1 having an exhaust system 11, a process gas introduction system 12 that introduces a process gas into the processing chamber 1, and plasma is introduced into the processing chamber by applying energy to the introduced process gas. And a substrate stage 2 for holding the substrate at a position to be processed by the plasma.
[0004]
In the apparatus shown in FIG. 9, plasma is formed by high frequency discharge. That is, the plasma forming means is constituted by a high-frequency power source 44 that sets a high-frequency electric field in the processing chamber 1. The substrate stage 2 includes a lower electrode 4 for high frequency discharge as a part thereof, and a high frequency power supply 44 is connected to the lower electrode 4.
[0005]
An upper electrode 5 is provided above the lower electrode 4. The upper electrode 5 is grounded together with the processing chamber 1. The upper electrode 5 and the lower electrode 4 face each other in parallel like a pair of parallel plate electrodes.
The upper electrode 5 is also used as a process gas supply path into the processing chamber 1. That is, the upper electrode 5 is hollow and has a large number of gas blowing holes 51 on the lower surface. The piping of the process gas introduction system 12 is connected to the upper electrode 5 so that the process gas is once supplied to the internal space of the upper electrode 5 and then blown out from the gas blowing holes 51 to be introduced into the lower discharge space. It has become.
[0006]
The substrate stage 2 is configured to place and hold the substrate 9 on the upper surface. The substrate stage 2 includes a substrate temperature control mechanism 3 for controlling the temperature of the substrate 9. The substrate temperature control mechanism 3 circulates a heating medium through a cavity 41 formed in the substrate stage 2, and a heating medium supply pipe 32 connected to a heating medium inlet 42 connected to the cavity 41, The heating medium discharge pipe 33 is connected to the connected hot medium outlet 43, and the circulator 31 is provided between the heating medium supply pipe 32 and the heating medium discharge pipe 33.
In addition, in order to improve the accuracy of temperature control by the substrate temperature control mechanism 3, an electrostatic chucking mechanism 45 that chucks the substrate 9 to the substrate stage 2 by static electricity is provided. The electrostatic adsorption mechanism 45 mainly includes an adsorption electrode 451 embedded in a dielectric block 21 provided as an upper part of the substrate stage 2 and an adsorption power source 452 that applies a DC voltage to the adsorption electrode 451. Has been. The periphery of the substrate stage 2 is covered with an insulating block 24.
[0007]
In the apparatus shown in FIG. 9, when the substrate 9 is placed on the substrate stage 2, the electrostatic adsorption mechanism 45 operates to electrostatically adsorb the substrate 9 to the substrate stage 2. Thereafter, the process gas introduction system 12 operates to introduce process gas at a predetermined flow rate, and the plasma forming means operates in this state. That is, the high frequency power supply 44 operates to generate high frequency discharge in the process gas, and plasma is formed. A predetermined process is performed on the surface of the substrate 9 by the action of the plasma.
For example, a fluorocarbon-based gas is introduced to form a plasma, and the surface of the substrate 9 is etched using a reaction with a fluorocarbon radical or a fluorine radical generated in the plasma. At this time, reactive ion beam etching (RIE) in which an electric field is set between the plasma and the substrate 9 and ions in the plasma are incident on the substrate 9 is preferable because anisotropic etching can be performed.
[0008]
Specifically, a high frequency voltage is applied to the substrate 9, and a negative self-bias potential is applied to the substrate 9 by the interaction between the high frequency and the plasma. An electric field perpendicular to the substrate 9 is set by this negative self-bias potential, and ions in the plasma are incident vertically. And the energy by ion incidence acts on radical etching reaction, and it etches efficiently only in the part into which ion entered. As a result, etching proceeds vertically from the opening of the resist pattern, and etching without problems such as side etching is performed.
[0009]
A protective ring 23 is provided around the substrate holding surface of the substrate stage 2. The protection ring 23 is for protecting the surface of the substrate stage 2 from plasma. The surface portion of the substrate stage 2 that is not covered by the substrate 9 may be exposed to plasma during processing. When exposed to plasma, the surface is etched by the action of active species or the like in the plasma, and particles of the material of the substrate stage 2 are released into the processing chamber 1. The material of the substrate stage 2 is stainless steel or the like and is often different from the substrate 9. Therefore, if the particles adhere to the surface of the substrate 9, the surface may be soiled to cause a circuit defect or the like.
Therefore, a protective ring 23 is provided so as to cover the surface portion of the substrate stage 2 that may be exposed to plasma. The protection ring 23 is made of a material such as silicon similar to that of the substrate 9 and does not have any problem even if it is etched.
[0010]
[Problems to be solved by the invention]
In the above-described conventional plasma processing apparatus, there is a problem that products are deposited on the surface of the substrate stage 2 or the surface of a member existing on the side of the substrate holding surface of the substrate stage 2. This problem will be described with reference to FIG. FIG. 10 is a diagram for explaining the problems of the conventional plasma processing apparatus shown in FIG. 9, and is an enlarged view of the peripheral portion of the substrate stage 2 shown in FIG.
[0011]
In the plasma etching apparatus as an example of the plasma processing apparatus described above, product deposition occurs as an etching competition phenomenon. For example, when etching is performed by introducing a fluorocarbon gas as described above, a polymer film composed of fluorine and carbon is deposited as a product. In this case, since the etching rate is much higher than the deposition rate on the surface of the substrate or the like, such a film is not actually deposited.
[0012]
However, as shown in FIG. 10 (1), the product 10 is actually deposited on the side surface of the dielectric block 21 provided as a part of the substrate stage 2. The reason for this is related to the fact that the apparatus shown in FIG. 9 is an apparatus that performs RIE. That is, as described above, in RIE, etching is performed using the energy of ion incidence. Therefore, the etching does not proceed sufficiently even where active species are present, where ions are not incident.
As shown in FIG. 10A, the upper surface (substrate holding surface) of the dielectric block 21 is slightly smaller than the substrate 9, so that the ion incidence on the side surface of the dielectric block 21 is shielded by the substrate 9. Become. For this reason, ions are not sufficiently incident on the side surfaces of the dielectric block 21 and etching does not proceed sufficiently. As a result, only the deposition phenomenon proceeds and the product 10 is deposited.
The deposited product 10 may peel off due to internal stress or the like. The peeled product 10 becomes particles and floats in the processing chamber 1. If these particles adhere to the surface of the substrate 9, a fatal defect such as a circuit breakage may occur.
[0013]
Further, the accumulated product 10 may be scattered when the substrate 9 is carried in or out, and may adhere to the substrate holding surface as shown in FIG. When the substrate 9 is placed with the product 10 attached to the substrate holding surface, the contact between the substrate holder 2 and the substrate 9 is deteriorated, and the temperature control reproducibility by the substrate temperature control mechanism 3 is sufficiently obtained. It becomes impossible. In addition, since a portion having poor thermal contact is locally formed, the temperature of the substrate 9 becomes non-uniform, and the uniformity of the plasma processing also becomes poor. Further, since the attitude of the substrate 9 with respect to the plasma also changes, the manner in which the self-bias potential is applied becomes non-uniform, and this also causes the reproducibility and uniformity of the plasma processing to deteriorate.
[0014]
Such deposition of the product 10 is a phenomenon generally observed not only in the plasma etching apparatus described above but also in other plasma processing apparatuses. For example, since a plasma chemical vapor deposition (CVD) apparatus is originally a film deposition apparatus, film deposition on unnecessary places other than the surface of the substrate can be seen, and it has also been removed by an ashing (resist removal) apparatus. There is a phenomenon in which the residue of the resist is deposited as a product.
The invention of the present application was made to solve the problem of product deposition in such a plasma processing apparatus. By suppressing the product deposition, the generation of particles, the reduction in process reproducibility, etc. It has technical significance to prevent this problem.
[0015]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, the invention according to claim 1 of the present application is directed to a processing chamber provided with an exhaust system, a process gas introduction system for introducing a process gas into the processing chamber, and energy introduced to the introduced process gas. A plasma processing apparatus comprising plasma forming means for forming plasma in a processing chamber and a substrate stage for holding a substrate at a position to be processed by the plasma, the surface of the substrate stage or the substrate holding surface of the substrate stage A deposition suppressing gas supply system for supplying a deposition suppressing gas for suppressing the deposition of the product on the surface of the member provided on the side of the
The deposition suppression gas supply system allows the deposition suppression gas to flow to the side of the substrate stage via the substrate stage and the substrate.
Substrate holding surface of substrate stage Is Protrusions that come in contact with the held substrate and protrusions that do not contact the substrate It is formed in an uneven shape having The protrusion that does not contact the substrate extends along the periphery of the substrate holding surface. Circumferential This is a protrusion that touches the substrate. Circumferential It has the structure of being formed inside the protrusion.
In order to solve the above problems, the claims of the present application 2 The invention described is the above claim. 1 In this configuration, the protrusions that come into contact with the substrate have a structure in which a plurality of protrusions are provided at equal intervals.
In order to solve the above problems, the claims of the present application 3 The invention described is the above claim. 1 or 2 In the configuration, an electrostatic chucking mechanism that chucks the substrate to the substrate stage by static electricity is provided, and the total area of the surface of the protrusion that contacts the substrate that contacts the substrate is 5% or more of the area of the back surface of the substrate 10. % Or less.
In order to solve the above problems, the claims of the present application 4 The invention described is the above claim. 1 to 3 In any one of the configurations, the product is generated and deposited by a reaction of a gas introduced into the processing chamber, and the deposition suppressing gas is configured to reduce a precursor concentration.
In order to solve the above problems, the claims of the present application 5 The invention described is the above claim. 1 to 4 In any one of the configurations, the substrate stage includes a substrate temperature control mechanism that controls the temperature of the substrate while maintaining the substrate stage at a predetermined temperature, and heat is applied between the substrate stage and the substrate. A heat transfer gas supply system for supplying a heat transfer gas to be transmitted between the substrate stage and the substrate is provided. The heat transfer gas supply system is also used as the deposition suppression gas supply system. It has the composition of being.
In order to solve the above problems, the claims of the present application 6 The invention described is the above claim. 1 to 5 In any one of the configurations, a side-side gas supply path that guides the deposition-inhibiting gas to the side of the substrate stage is provided in the substrate stage, and the deposition-inhibiting gas supply system includes the substrate stage and In addition to passing between the substrate and the substrate, the gas for suppressing deposition is supplied from the side surface of the substrate stage via the gas supply path for side surface.
In order to solve the above problems, the claims of the present application 7 The invention described is the above claim. 1 to 6 In any configuration, the deposition suppression gas supply system includes a flow rate regulator that adjusts a flow rate of the deposition suppression gas to be supplied. The flow rate regulator adjusts the flow rate of the deposition suppression gas to 10 cc / min. The flow rate is 50 cc / min or less.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below. FIG. 1 is a schematic cross-sectional view showing the configuration of the plasma processing apparatus according to the first embodiment of the present invention. In the following description, a plasma etching apparatus will be described as an example of a plasma processing apparatus, as in the description of the prior art.
[0017]
The plasma processing apparatus shown in FIG. 1 is introduced into a processing chamber 1 having an exhaust system 11 and a process gas introduction system 12 for introducing a process gas into the processing chamber 1, similarly to the conventional apparatus shown in FIG. Plasma forming means for applying energy to the processed gas to form plasma in the processing chamber 1, and a substrate stage 2 for holding the substrate 9 at a position to be processed by the plasma.
[0018]
The processing chamber 1 is an airtight container having a gate valve (not shown) and is electrically grounded. Then, the processing chamber 1 is 10 by an exhaust system 11. ^-6 -10 ^-7 It is configured to exhaust to about Torr. The exhaust system 11 includes a vacuum pump such as a turbo molecular pump, and an exhaust speed regulator (not shown) is provided.
The process gas introduction system 12 can introduce a process gas necessary for plasma processing at a predetermined flow rate. The apparatus of this embodiment is designed to perform plasma etching as in the prior art, and introduces a fluorocarbon-based gas as a process gas. Specifically, the process gas introduction system 12 includes a gas cylinder 121 storing a process gas such as carbon tetrafluoride, a pipe 122 connecting the processing chamber 1 and the gas cylinder 121, a valve 123 provided in the pipe 122, and a flow rate adjustment. It is mainly composed of the device 124.
[0019]
The substrate stage 2 is a table-like member that holds the substrate 9 at a position exposed to plasma in the processing chamber 1, and holds the substrate 9 on the upper surface thereof. The substrate stage 2 includes a dielectric block 21 that is a member that directly holds the substrate 9 and a lower electrode 4 on which the dielectric block 21 is placed.
[0020]
An upper electrode 5 is provided above the substrate stage 2 as in the conventional apparatus. In the present embodiment, the upper electrode 5 is provided in the processing chamber 1 via an insulating material 53. The upper electrode 5 and the lower electrode 4 face each other in parallel like a pair of parallel plate electrodes.
The upper electrode 5 is also used as a process gas supply path into the processing chamber 1. That is, the upper electrode 5 is hollow and has a large number of gas blowing holes 51 on the lower surface. The piping 122 of the process gas introduction system 12 is connected to the upper electrode 5, and the process gas is once supplied to the internal space of the upper electrode 5, then blown out from the gas blowing holes 51 and introduced into the lower discharge space. It is like that.
[0021]
As the plasma forming means, one that applies high frequency power to the process gas introduced into the processing chamber 1 from the process gas introduction system 12 and forms plasma by high frequency discharge is adopted. Specifically, the plasma forming means is constituted by a plasma high-frequency power source 52 connected to the upper electrode 5 described above. The plasma high-frequency power source 52 has a frequency of 13.56 MHz and a maximum output of about 2500 W. A matching unit (not shown) is provided between the upper electrode 5 and the plasma high-frequency power source 52.
[0022]
Further, in the apparatus of the present embodiment, an electric field setting means for setting an electric field perpendicular to the substrate 9 is provided so that ions are extracted from the plasma and incident perpendicularly on the substrate 9. As the electric field setting means, one that applies a negative self-bias potential to the substrate 9 by the interaction between high-frequency power and plasma is employed. Specifically, the electric field setting means is configured by a high frequency power supply 44 connected to the lower electrode 4. An appropriate capacitance is required between the substrate 9 and the high-frequency power supply 44 to provide a self-bias potential. In the present embodiment, the above-described dielectric block 21 provides this capacitance.
[0023]
When a high frequency voltage is applied to the lower electrode 4 by the high frequency power supply 44, electrons and ions in the plasma act on the charge and discharge of this capacitance, and a negative self-bias potential is generated on the substrate 9 due to the difference in mobility between the electrons and ions. Since the space potential of the plasma is almost 0 V, an electric field in which the potential gradually decreases toward the substrate 9 is set between the plasma and the substrate 9. Positive ions in the plasma are vertically incident on the substrate 9 by this electric field.
Further, as in the case of the conventional apparatus, the high-frequency power source 44 may form plasma without providing the plasma high-frequency power source 52 on the upper electrode 5 described above.
[0024]
The substrate stage 2 includes a substrate temperature control mechanism 3 as in the conventional apparatus. In the present embodiment, a heating medium lower than room temperature is circulated in the substrate stage 2 to cool the substrate 9 via the substrate stage 2. As this heating medium, a liquid having a melting point lower than that of water, for example, FX-300 manufactured by Sumitomo 3M or Garten HT manufactured by Augmont is used. By keeping this heating medium at a predetermined temperature in the range of about −20 to 30 ° C., the substrate 9 is cooled and maintained at a predetermined temperature in the range of about 70 to 120 ° C.
[0025]
In the present embodiment, as in the conventional apparatus, an electrostatic adsorption mechanism 45 that adsorbs the substrate 9 to the substrate stage 2 by static electricity is provided. The periphery of the substrate stage 2 is covered with an insulating block 24. The insulating block 24 is for preventing the substrate stage 2 from being damaged by plasma, and is formed of a heat-resistant insulator such as ceramic, fluorine resin such as polytetrafluoroethylene (Teflon), polyimide resin or the like. .
[0026]
The major feature of the present embodiment is that a deposition suppressing gas for preventing the product from depositing on the surface of the substrate stage 2 or the surface of a member provided on the side of the substrate holding surface of the substrate stage 2 is used. This is the point that a deposition suppressing gas supply system 25 is provided. In the apparatus of the present embodiment, there is a risk that a product is deposited on the surface of the dielectric block 21 provided as a part of the substrate stage 2 or the inner side surface of the protective ring 23, and these surfaces are “the surface of the substrate stage or the substrate. This corresponds to the “surface of a member provided on the side of the substrate holding surface of the stage” (hereinafter referred to as a deposition surface).
[0027]
The deposition suppressing gas supply system 25 is configured to supply deposition suppressing gas to the side of the substrate stage 2 through the space inside the substrate stage 2 and between the substrate stage 2 and the substrate 9. Specifically, the deposition suppression gas supply system 25 includes a gas cylinder 251 in which deposition suppression gas is stored, a pipe 252 that connects the gas cylinder 251 and the substrate stage 2, a valve 253 provided on the pipe 252, and a flow rate adjustment. Mainly composed of a container 254.
[0028]
In the substrate stage 2, a gas supply path 255 (hereinafter referred to as “upper gas supply path”) for supplying a deposition suppression gas to a space between the substrate stage 2 and the substrate 9, which is a space above the substrate stage 2, is formed. Has been. The upper gas supply path 255 is provided so as to penetrate the center of the substrate stage 2 vertically. A pipe 252 of the deposition suppressing gas supply system 25 is connected to the lower end opening of the upper gas supply path 255 in an airtight manner, and the deposition suppressing gas passes through the upper gas supply path 255 to the substrate stage 2. And the substrate 9 are supplied.
[0029]
In the present embodiment, the shape of the substrate holding surface is devised so that the deposition suppressing gas supplied between the substrate stage 2 and the substrate 9 flows out to the side of the substrate stage 2 efficiently. This point will be described with reference to FIGS. FIG. 2 is a schematic plan view illustrating the shape of the substrate holding surface.
[0030]
As can be seen from FIGS. 1 and 2, the substrate holding surface of the substrate stage 2 is a surface having complicated irregularities. Specifically, as shown in FIG. 2, a circumferential protrusion 29 is provided so as to extend along the periphery of the substrate holding surface. The circumferential protrusion 29 has a circumferential shape with a width of about 1.5 mm. A plurality of small protrusions 28 are provided inside the circumferential protrusion 29. The small protrusions 28 have a columnar shape with a diameter of about 3 mm and are provided at an equal interval of about 5 mm. Note that the upper end opening of the upper gas supply path 255 is located at the center of the substrate holding surface.
[0031]
The height of the circumferential protrusion 29 is slightly lower than that of the small protrusion 28. Therefore, when the substrate 9 is held on the substrate stage 2, the upper end surface of the small protrusion 28 contacts the back surface of the substrate 9, but the upper end surface of the circumferential protrusion 29 does not contact the back surface of the substrate 9. It has become. For example, the height of the small protrusion 28 is about 10 μm, and the height of the circumferential protrusion 29 is about 5 μm.
The deposition suppression gas supplied to the substrate stage 2 by the deposition suppression gas supply system 25 flows through the upper gas supply path 255 in the substrate stage 2, and passes between the substrate 9 and the substrate stage 2 from the upper end opening. It flows out into space. The deposition suppressing gas that has flowed out flows through the small protrusions 28 and flows out to the side of the substrate stage 2 through the gap between the circumferential protrusions 29 and the substrate 9.
[0032]
Even when the substrate holding surface is not an uneven surface composed of the small protrusions 28 and the circumferential protrusions 29 as described above, but a normal flat surface, it is possible to flow the deposition suppressing gas. This is because unless there is a special process such as mirror finishing, there is microscopic unevenness and a minute gap is formed, so that the substrate 9 and the substrate stage 2 are connected through the upper gas supply path 255. When the deposition suppressing gas is supplied in the meantime, the deposition suppressing gas can flow through the minute gap and flow out to the side of the substrate stage 2. However, in this case, since the gap is small, the conductance is small, and the deposition suppressing gas can be flowed only at a small flow rate. If an attempt is made to increase the flow rate, the substrate 9 floats from the substrate stage 2 due to the pressure.
On the other hand, in the present embodiment, as described above, since a considerably large unevenness composed of the small protrusions 28 and the circumferential protrusions 29 is formed on the substrate holding surface, the conductance of the deposition suppressing gas is sufficiently large. For this reason, the substrate 9 does not float even if the deposition suppressing gas is flowed at a necessary flow rate.
[0033]
The substrate 9 processed on the substrate stage 2 is lifted from the substrate stage 2 by an arm of a transfer robot (not shown) after the operation of the suction power source 452 is stopped. In this case, if the area of the upper end surface of the small protrusion 28 that contacts the back surface of the substrate 9 exceeds 10% of the area of the back surface of the substrate 9, the effect of the residual charge on the upper end surface of the small protrusion 28 increases and the residual adsorption. There is a possibility that the substrate 9 may not be lifted well due to the force.
[0034]
Conversely, if the total area of the upper end surface of the small protrusion 28 is reduced, the conductance increases and the flow rate of the deposition suppressing gas can be increased, but there is a possibility that the electrostatic adsorption of the substrate 9 may not be sufficient. In order to ensure a sufficient electrostatic attraction force, it is preferable that the total area of the upper end surface of the small protrusion 28 does not fall below 5% of the area of the back surface of the substrate 9. Eventually, in order to allow the deposition suppressing gas to flow at a sufficient flow rate while ensuring a sufficient electrostatic attraction force, the total area of the upper end surface of the small protrusion 28 is set to about 5 to 10% of the area of the back surface of the substrate 9. Is preferred.
[0035]
Next, the situation where the deposition of the product 10 is suppressed by the outflow of the deposition suppressing gas will be described with reference to FIG. FIG. 3 is a cross-sectional schematic partial view illustrating a situation where the deposition suppressing gas suppresses the accumulation of product.
As described above, in the plasma processing apparatus, a product is generated by a specific reaction and is deposited on a deposition surface. Often the product is ultimately produced by a surface reaction at the deposition surface. In this case, the substance (precursor) at the stage before the final product has been flying into the space facing the deposition surface (hereinafter, the deposition space). In the apparatus of the present embodiment, the precursor has come into the space surrounded by the peripheral portion of the substrate 9 that protrudes from the substrate holding surface, the protective ring 23, and the substrate stage 2. This precursor reaches the deposition surface and deposits the product through a final surface reaction at the deposition surface.
[0036]
Here, as described above, the deposition-inhibiting gas flowing out to the side of the substrate stage 2 is supplied to the deposition space and is mixed with the precursor flying into this space. As a result, the concentration of the precursor in the deposition space decreases, and the probability that the precursor reaches the deposition surface and changes to a product by a surface reaction decreases. Further, the deposition suppressing gas that flows out to the side of the substrate stage 2 diffuses through the deposition space and is finally exhausted by the exhaust system 11. At this time, the molecules of the deposition suppressing gas may collide with the precursor flying into the deposition space and push it back, preventing the precursor from reaching the deposition surface. Such physical action also suppresses product deposition on the deposition surface.
[0037]
Further, in the apparatus according to the present embodiment, there is a flow of the deposition suppressing gas that flows along the back surface of the substrate 9 passing between the circumferential protrusion 29 on the substrate holding surface and the substrate 9. The flow of the deposition suppressing gas has an action of pushing back the precursor flying toward the back surface of the peripheral portion of the substrate 9 and the upper end surface of the circumferential protrusion 29. Even if a product is deposited on the back surface of the substrate 9 or the upper end surface of the circumferential projection 29, it is easily peeled off by the flow of the deposition-inhibiting gas. For this reason, it is more effectively prevented that the substrate 9 is lifted by the deposition of the product on the substrate holding surface as has been conventionally seen.
[0038]
Even if the product deposition is suppressed, the precursor cannot reach the deposition surface completely, so that the product is deposited at a very low deposition rate. Accordingly, it is inevitable that the product 10 is deposited as shown in FIG. 3 while repeating a great number of plasma treatments. However, as shown in FIG. 3, the product 10 is only deposited in a space lower than the height of the peripheral edge of the substrate holding surface of the substrate stage 2. As described above, this is due to the physical action of the deposition suppressing gas that flows laterally along the back surface of the substrate 9 from the periphery of the substrate holding surface of the substrate stage 2. That is, since the precursor is pushed back by the flow of the deposition suppressing gas, the product 10 is not deposited in the space above the substrate holding surface of the substrate stage 2. Therefore, the deposition of the product 10 does not reach the back surface of the substrate 9 or the substrate holding surface of the substrate stage 2 as in the prior art.
[0039]
In addition, the configuration in which the circumferential protrusion 29 is provided can increase the flow rate of the deposition suppressing gas flowing out to the side of the substrate stage 2 as compared with the configuration in which the circumferential projection 29 is not provided. In other words, the presence of the circumferential protrusion 29 reduces the cross-sectional area of the deposition suppressing gas flow path in the peripheral portion of the substrate holding surface. As a result, the flow rate of the deposition suppressing gas when flowing in the vicinity of the upper end surface of the circumferential protrusion 29 is increased. For this reason, the effect of suppressing the accumulation of products on the back surface of the substrate 9 and the upper end surface of the circumferential projection 29 can be obtained more highly.
[0040]
In addition, the deposition suppressing gas supply system 25 in this embodiment is also used as a heat transfer gas supply system for efficiently transferring heat from the substrate temperature control mechanism 3 to the substrate 9. As described above, in the apparatus of this embodiment, the substrate temperature control mechanism 3 is provided in the substrate stage 2, and the substrate 9 is brought to a predetermined temperature by exchanging heat with the substrate 9 via the substrate stage 2. It comes to adjust. At this time, since the inside of the processing chamber 1 is vacuumed by the exhaust system 11, in the conventional apparatus, the space between the substrate stage 2 and the substrate 9 is also vacuumed. Therefore, the heat transfer efficiency between the substrate stage 2 and the substrate 9 is reduced.
[0041]
On the other hand, in the apparatus of this embodiment, the deposition suppressing gas supplied by the deposition suppressing gas supply system 25 increases the pressure in the space between the substrate stage 2 and the substrate 9. As a result, the heat transfer efficiency between the substrate stage 2 and the substrate 9 is improved, and the efficiency and accuracy of temperature control by the substrate temperature control mechanism 3 are improved.
In the present embodiment, the deposition suppressing gas supply system 25 that is also used as the heat transfer gas supplying system uses helium as the deposition suppressing gas. Helium is used because it is a rare gas, so that it does not affect the plasma processing even if it flows into the processing chamber 1 from between the substrate 9 and the circumferential projection 29. Helium is also suitable as a heat transfer gas because it has a high heat transfer efficiency among rare gases.
[0042]
The deposition suppressing gas supply system 25 preferably supplies the deposition suppressing gas at a flow rate of 10 to 50 cc / min. In order to improve the heat transfer efficiency, it is preferable to supply a larger amount of deposition suppression gas, but considering the influence on the plasma processing, the total gas flow rate introduced into the processing chamber 1 (process gas + deposition suppression) The upper limit of the flow rate of the deposition-inhibiting gas is about 10%. Further, when the deposition suppressing gas has a flow rate of about 10 cc / min or less, there is a possibility that the effect of suppressing the product deposition due to the decrease in the precursor concentration is insufficient or the effect of improving the heat transfer efficiency is not sufficient. .
[0043]
Next, the operation in the plasma processing apparatus of the first embodiment will be described.
First, the substrate 9 is carried into the processing chamber 1 through a gate valve (not shown) by an arm of a transfer robot (not shown). When the substrate 9 is placed on the substrate stage 2, the electrostatic attraction mechanism 45 operates to electrostatically attract the substrate 9 to the substrate stage 2. When the inside of the processing chamber 1 is evacuated to a predetermined pressure by the exhaust system 11, the process gas introduction system 12 operates and a process gas such as carbon tetrafluoride is introduced at a predetermined flow rate. In parallel, a deposition suppression gas is supplied between the dielectric block 21 and the substrate 9 by the deposition suppression gas supply system 25, and the side of the substrate stage 2 extends between the substrate 9 and the circumferential protrusion 29. To leak.
[0044]
When high frequency power is applied to the upper electrode 5 by the plasma high frequency power source 52 constituting the plasma forming means, high frequency discharge is generated in the introduced process gas, and the process gas is turned into plasma. At the same time, when a high frequency voltage is applied to the lower electrode 4 by the high frequency power supply 44, a negative self-bias voltage is generated on the surface of the substrate 9 due to the interaction between the high frequency and the plasma. By this negative self-bias voltage, an electric field perpendicular to the substrate 9 is set, and ions in the plasma are incident vertically. Fluorocarbon radicals are generated in the plasma. Then, the surface of the substrate 9 is etched by the reaction with the radicals using the energy of the incident ions.
[0045]
At this time, as described above, the deposition suppressing gas is supplied to the side of the substrate stage 2, whereby the concentration of the precursor, which is a causative substance of the product, is reduced, and the product is prevented from being deposited. . For this reason, generation | occurrence | production of the particle | grains resulting from peeling of the deposited product is suppressed. Further, there is no change in the posture of the substrate 9 due to the deposition of the product as seen in the past, and a process with excellent reproducibility can be performed. For this reason, in this embodiment, the yield of products can be dramatically improved as compared with conventional devices.
[0046]
Next, the plasma processing apparatus of 2nd embodiment of this invention is demonstrated. FIG. 4 is a schematic cross-sectional view showing the configuration of the plasma etching apparatus of the second embodiment.
In the first embodiment described above, the deposition suppressing gas is supplied between the dielectric block 21 and the substrate 9, and the deposition suppressing gas flows out to the side of the substrate stage 2. In the second embodiment, the deposition suppressing gas is supplied from the side surface of the substrate stage 2 to the side of the substrate stage 2.
Specifically, in the substrate stage 2, a gas supply path (hereinafter referred to as a side surface gas supply path) 211 that supplies deposition suppression gas from the side surface of the substrate stage 2 to the side of the substrate stage 2 is provided. . The configuration of the side gas supply path 211 will be described with reference to FIGS. 4 and 5. FIG. 5 is a cross-sectional view taken along one-dot chain line XX in the apparatus shown in FIG.
[0047]
As shown in FIGS. 4 and 5, the side gas supply path 211 includes an annular channel 211A provided in the center, and a radial channel 211B provided so as to extend radially from the annular channel 211A. The vertical channel 211C is provided so as to extend vertically downward from the annular channel 211A. The vertical channel 211 </ b> C reaches the lower surface of the substrate stage 2 and is connected to a pipe 272 of the deposition suppressing gas supply system 27. Further, the radial flow path 211B reaches the side surface of the substrate stage 2, and the tip thereof is a gas outlet 211D.
[0048]
The deposition suppression gas supply system 27 includes a gas cylinder 271 storing a deposition suppression gas such as argon, a gas cylinder 271, a pipe 272 connecting the substrate stage 2, a valve 273 provided on the pipe 272, and a flow rate regulator 274. And is composed mainly of. When the deposition suppression gas supply system 27 supplies the deposition suppression gas through the pipe 272, the deposition suppression gas ascends the vertical channel 211C, reaches the annular channel 211A, and temporarily accumulates in the annular channel 211A. . The deposition suppressing gas flows from the annular channel 211 </ b> A through the radial channel 211 </ b> B to the gas outlet 211 </ b> D on the side surface of the substrate stage 2 and is supplied to the side of the substrate stage 2.
[0049]
Next, a situation in which the deposition suppressing gas suppresses product deposition in the second embodiment will be described with reference to FIG. FIG. 6 is a schematic cross-sectional partial view illustrating a situation in which the deposition suppressing gas suppresses product deposition in the second embodiment.
As described above, in the second embodiment, the deposition suppressing gas is supplied from the side surface of the substrate stage 2 to the deposition space. As a result, as in the case of the first embodiment, the concentration of the precursor flying into the deposition space is reduced, and product accumulation on the deposition surface is prevented.
[0050]
Also in this second embodiment, the product deposition on the deposition surface cannot be completely zero, and as shown in FIG. 6, it is avoided that the product 10 is deposited at a very low deposition rate. I can't. As shown in FIG. 6, the product accumulates in a space below the gas outlet 211 </ b> D on the side surface of the substrate stage 2. This is because in the space above the gas outlet 211D, there is a flow of gas for suppressing deposition from the gas outlet 211D, and due to the physical action of this flow, product deposition is almost zero.
[0051]
Here, as can be seen by comparing FIG. 3 and FIG. 6, in the second embodiment, the final product 10 is deposited in a smaller amount than in the first embodiment. This means that there are few substances that cause the generation of particles. Therefore, the probability of the generation of particles is further reduced in the second embodiment compared to the first embodiment.
[0052]
As the deposition suppressing gas in the second embodiment, a rare gas such as argon or an inert gas is preferably used. In the second embodiment, the flow rate of the deposition suppressing gas is preferably 10 to 50 cc / min. If it is less than 10 cc / min, the amount of the deposition inhibiting gas is insufficient, and there is a possibility that the product deposition inhibiting effect due to the decrease in the precursor concentration cannot be obtained sufficiently. If the flow rate is higher than 50 cc / min or more than 10% of the flow rate of the process gas + the flow rate of the deposition suppression gas, the deposition suppression gas diffuses into the space above the substrate 9 and inhibits the reaction necessary for the plasma processing. There is a fear.
[0053]
Also in the second embodiment, a heat transfer gas supply system 26 for efficiently transferring heat from the substrate temperature control mechanism 3 to the substrate 9 is provided. However, unlike the first embodiment, the heat transfer gas supply system 26 is not also used as a deposition suppression gas supply system. The heat transfer gas supply system 26 includes a gas cylinder 261 storing a heat transfer gas such as helium, a pipe 262 connecting the gas cylinder 261 and the substrate stage 2, a valve 263 provided on the pipe 262, and a flow rate controller. H.264.
An upper gas supply path 255 is provided at the center of the substrate stage 2 as in the first embodiment. The pipe 262 and the upper gas supply path 255 are hermetically connected so that heat transfer gas is supplied between the dielectric block 21 and the substrate 9.
[0054]
Further, in the second embodiment, the supplied heat transfer gas does not play a role of suppressing deposition, and is thus configured not to flow out to the side of the substrate stage 2. Specifically, the substrate holding surface of the dielectric block 21 is formed with small protrusions 28 and circumferential protrusions 29 as in the first embodiment. However, unlike the first embodiment, the circumferential projection 29 has the same height as the small projection 28, and when the substrate 9 is held on the substrate stage 2, the circumferential projection 29 is positioned on the circumferential projection 29 together with the upper end surface of the small projection 28. The end surface is also in contact with the back surface of the substrate 9. Therefore, when the heat transfer gas is supplied between the substrate stage 2 and the substrate 9, the heat transfer gas does not flow out to the side of the substrate stage 2.
[0055]
Since the heat transfer gas does not flow to the side of the substrate stage 2, the amount of heat transfer gas supplied is smaller than the deposition preventing gas in the first embodiment. That is, after the substrate 9 is electrostatically attracted to the substrate stage 2, the heat transfer gas supply system 26 is operated to supply a predetermined amount of heat transfer gas, and the space between the substrate 9 and the substrate stage 2 is When the pressure reaches a predetermined value, the supply of the heat transfer gas is stopped.
In addition, the second embodiment has an advantage that the type and flow rate of the heat transfer gas can be determined regardless of the technical problem of suppressing the accumulation of products.
[0056]
Next, a plasma processing apparatus according to a third embodiment of the present invention will be described. FIG. 7 is a schematic cross-sectional view showing the configuration of the plasma processing apparatus of the third embodiment. The apparatus of the third embodiment includes a first deposition suppression gas supply system 6 and a second deposition suppression gas supply system 7.
First, the first deposition suppressing gas supply system 6 supplies a deposition suppressing gas between the substrate stage 2 and the substrate 9. When the deposition suppressing gas is supplied between the substrate stage 2 and the substrate 9, the deposition suppressing gas flows out to the side of the substrate stage 2.
[0057]
Specifically, the substrate stage 2 is provided with an upper gas supply path 255 similar to that of the first embodiment. The upper gas supply path 255 is airtightly connected to the pipe 62 of the first deposition suppressing gas supply system 6 so that the deposition suppressing gas is supplied between the substrate stage 2 and the substrate 9. It has become. Similarly, the first deposition suppressing gas supply system 6 is provided on the piping 62, a gas cylinder 61 storing a deposition suppressing gas such as helium, a pipe 62 connecting the gas cylinder 61 and the substrate stage 2, and the piping 62. The valve 63 and the flow controller 64 are mainly configured.
[0058]
Similarly, small protrusions 28 and circumferential protrusions 29 are provided on the substrate holding surface of the substrate stage 2. The configurations of the small protrusions 28 and the circumferential protrusions 29 are the same as those in the first embodiment. That is, when the deposition suppression gas is supplied between the dielectric block 21 and the substrate 9 via the upper gas supply path 255 by the first deposition suppression gas supply system 6, the deposition suppression gas is small. It flows so as to pass between the projections 28 and flows out from between the substrate 9 and the circumferential projection 29 to the side of the substrate stage 2.
[0059]
On the other hand, the second deposition suppression gas supply system 7 is configured to supply deposition suppression gas from the side surface of the substrate stage 2. Specifically, the substrate stage 2 is provided with a side gas supply path 211 as in the second embodiment. The side gas supply path 211 and the pipe 72 of the second deposition suppression gas supply system 7 are hermetically connected, and the deposition suppression gas is supplied from the side surface of the substrate stage 2. Yes. Similarly, the second deposition suppressing gas supply system 7 is provided on the piping 72, a gas cylinder 71 that stores a deposition suppressing gas such as argon, a pipe 72 that connects the gas cylinder 71 and the substrate stage 2, and the like. The valve 73 and the flow controller 74 are mainly configured.
[0060]
Next, the situation where the deposition suppressing gas suppresses the deposition of products in the third embodiment will be described with reference to FIG. FIG. 8 is a schematic cross-sectional partial view illustrating a situation in which the deposition suppressing gas suppresses product deposition in the third embodiment.
[0061]
Also in the third embodiment, the concentration of the precursor flying into the deposition space is reduced by the deposition suppression gas supplied from the first deposition suppression gas supply system 6 and the second deposition suppression gas supply system 7. In addition, product accumulation on the deposition surface is suppressed. Further, at this time, the first deposition suppressing gas supply system 6 extends from the periphery of the substrate holding surface of the substrate stage 2 (the upper end surface of the circumferential protrusion 29) to the side of the substrate stage 2 along the back surface of the substrate 2. Since the deposition preventing gas is allowed to flow out, the deposition of the product on the back surface of the substrate 9 and the periphery of the substrate holding surface is particularly suppressed by the physical action of the deposition suppressing gas. Although it is inevitable that the product is deposited at an extremely low deposition rate, the second deposition suppression gas supply system 7 supplies the deposition suppression gas from the side surface of the substrate stage 2. As in the case of the embodiment, the product deposition stops halfway, and the generation of particles is further suppressed.
[0062]
The first deposition suppression gas supply system 6 in the third embodiment is also used as a heat transfer gas supply system, as in the first embodiment. That is, the second deposition preventing gas supply system 7 only needs to supply a rare gas such as argon or an inert gas, but the first deposition preventing gas supply system 6 uses a gas with good heat transfer efficiency such as helium. It is configured to supply. However, since the deposition preventing gas is supplied from the two paths, the gas flow rate of the first deposition preventing gas supply system 6 may be smaller than that of the deposition suppressing gas supply system 7 in the first embodiment. For the same reason, the gas flow rate of the second deposition preventing gas supply system 7 is smaller than that of the second embodiment. The sum of the gas flow rate of the first deposition preventing gas supply system 6 and the gas flow rate of the second deposition preventing gas supply system 7 is about 10 to 50 cc / min or the total gas flow rate for the same reason as described above. It is preferable that it is 10% or less. The configuration in which the gas flow rate of the first deposition suppressing gas supply system 6 is small is a preferable configuration in the sense of reducing the risk of the substrate 9 floating from the substrate stage 2 due to the flow of a large flow rate of gas. ing.
[0063]
In the above description, the plasma etching apparatus is taken as an example, but the invention of the present application can be similarly applied to other plasma processing apparatuses such as a plasma CVD apparatus and an ashing apparatus.
Note that the invention of claim 1 does not require the precursor concentration to be lowered. This assumes that product deposition may not be the result of a certain reaction, and that there may be a configuration of product deposition inhibition that does not depend on a decrease in precursor concentration, as in the case of only the physical action described above. It is a thing.
[0064]
【The invention's effect】
As described above, according to the invention of claim 1 of the present application, it is possible to prevent the product from being deposited on the surface of the member existing on the side of the substrate stage by supplying the deposition suppressing gas. . As a result, the generation of particles due to product peeling is suppressed, and the quality of the plasma treatment can be improved. In addition, since the deposition suppressing gas flows along the substrate holding surface of the substrate stage and the back surface of the substrate, it is possible to physically suppress the deposition of products on these surfaces. Accordingly, problems such as a change in the posture of the substrate due to the deposition of the product on the substrate holding surface can be prevented, and plasma processing with excellent reproducibility can be performed. Furthermore, since the circumferential protrusion can increase the flow rate of the deposition suppressing gas flowing out to the side of the substrate stage, the effect of suppressing deposition can be further enhanced.
Claims 3 According to the invention of the above Claim 1 In addition to the effects of the invention, the deposition-inhibiting gas can be flowed at a sufficient flow rate while ensuring a sufficient electrostatic attraction force.
Claims 4 According to the invention of claim 1 to 3 In addition to the effects of any invention, a more favorable configuration is obtained when product deposition is the result of a certain reaction.
Claims 5 According to the invention of claim 1 to 4 In addition to the effects of any of the inventions, the efficiency and accuracy of substrate temperature adjustment by the substrate temperature control mechanism can be improved, and product deposition suppression and heat transfer efficiency can be improved with a single gas supply system. Is simplified.
Claims 6 According to the invention of claim 1 to 5 In addition to the effects of any of the inventions, since the deposition preventing gas flows out from the side surface of the substrate stage, the deposition of the product on the side surface of the substrate stage is further suppressed by physical action.
[Brief description of the drawings]
FIG. 1 is a schematic cross-sectional view showing a configuration of a plasma processing apparatus according to a first embodiment of the present invention.
2 is a schematic plan view illustrating the shape of a substrate holding surface of a substrate stage 2 in the plasma processing apparatus of FIG.
FIG. 3 is a schematic partial sectional view illustrating a situation in which the deposition suppressing gas suppresses product deposition in the first embodiment.
FIG. 4 is a schematic cross-sectional view showing a configuration of a plasma processing apparatus according to a second embodiment.
5 is a sectional view taken along one-dot chain line XX of the apparatus shown in FIG.
FIG. 6 is a schematic partial sectional view illustrating a situation in which a deposition suppressing gas suppresses product deposition in the second embodiment.
FIG. 7 is a schematic cross-sectional view showing a configuration of a plasma processing apparatus according to a third embodiment.
FIG. 8 is a schematic partial sectional view illustrating a situation in which a deposition suppressing gas suppresses product deposition in the third embodiment.
FIG. 9 is a front view showing a schematic configuration of a plasma etching apparatus as an example of a conventional plasma processing apparatus.
10 is a diagram for explaining a problem of the conventional plasma processing apparatus shown in FIG. 9, and is an enlarged view of a peripheral portion of the substrate stage 2 shown in FIG.
[Explanation of symbols]
1 Processing chamber
10 Product
11 Exhaust system
12 Process gas introduction system
2 Substrate stage
21 Dielectric block
211 Gas supply passage for side
23 Protective ring
24 Insulation block
25 Deposition control gas supply system
255 Upper gas supply path
26 Heat transfer gas supply system
27 Deposition control gas supply system
28 Small protrusions
29 Circumferential protrusion
3 Substrate temperature control mechanism
4 Lower electrode
44 High frequency power supply
45 Electrostatic adsorption mechanism
451 Adsorption electrode
452 Suction power supply
5 Upper electrode
51 Gas outlet
52 High frequency power supply for plasma
53 Insulation
6 First deposition suppression gas supply system
7 Second deposition suppression gas supply system
9 Board

Claims (7)

A processing chamber equipped with an exhaust system, a process gas introduction system for introducing a process gas into the processing chamber, a plasma forming means for applying energy to the introduced process gas to form plasma in the processing chamber, and processing by plasma And a substrate stage for holding the substrate at a position where the product is deposited on a surface of the substrate stage or a member provided on a side of the substrate holding surface of the substrate stage. A deposition suppression gas supply system for supplying a deposition suppression gas for suppressing
The deposition suppression gas supply system allows the deposition suppression gas to flow to the side of the substrate stage via the substrate stage and the substrate.
Substrate holding surface of the substrate stage, a projection in contact with the substrate held, is formed in an uneven shape having projections and not in contact with the substrate, the projection does not contact the substrate, extends along the periphery of the substrate holding surface A plasma processing apparatus, wherein the projection is a circumferential projection, and the projection in contact with the substrate is formed inside the circumferential projection.   The plasma processing apparatus according to claim 1, wherein the protrusions contacting the substrate are a plurality of protrusions provided at equal intervals. An electrostatic chucking mechanism for chucking the substrate to the substrate stage by static electricity is provided, and the total area of the surface of the protrusion contacting the substrate that contacts the substrate is 5% to 10% of the area of the back surface of the substrate. The plasma processing apparatus according to claim 1 , wherein the plasma processing apparatus is a plasma processing apparatus. The said product is produced | generated and deposited by reaction of the gas introduce | transduced in the processing chamber, The said deposition suppression gas reduces a precursor density | concentration, The any one of Claim 1 thru | or 3 characterized by the above-mentioned. A plasma processing apparatus according to claim 1. The substrate stage includes a substrate temperature control mechanism that controls the temperature of the substrate while maintaining the substrate stage at a predetermined temperature, and a heat transfer gas that transfers heat between the substrate stage and the substrate. Is provided between the substrate stage and the substrate, and the heat transfer gas supply system is also used as the deposition suppressing gas supply system. The plasma processing apparatus according to claim 1 . The substrate stage is provided with a side gas supply path for guiding the deposition suppressing gas to the side of the substrate stage, and the deposition suppressing gas supply system passes between the substrate stage and the substrate. 6. The plasma processing apparatus according to claim 1, wherein the deposition suppressing gas is supplied from the side surface of the substrate stage via the side surface gas supply path. The deposition suppression gas supply system includes a flow rate regulator that adjusts the flow rate of the deposition suppression gas to be supplied. The flow rate regulator adjusts the flow rate of the deposition suppression gas between 10 cc / min and 50 cc / min. The plasma processing apparatus according to claim 1 , wherein the plasma processing apparatus has a flow rate.

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