JP2004119987A - Semiconductor manufacturing equipment - Google Patents

Abstract

An object of the present invention is to provide a processing apparatus excellent in controllability of a wafer temperature by arbitrarily setting a pressure distribution of a heat conductive gas introduced between a semiconductor wafer and a wafer stage.
A semiconductor manufacturing apparatus includes: a plasma generation unit that generates plasma in a vacuum processing chamber; a wafer stage that holds a semiconductor wafer on a surface thereof; and a temperature control unit that controls the semiconductor wafer to a predetermined temperature. The wafer stage 6 has a first gas inlet 19 arranged near the center of the wafer stage, a second gas inlet 27 arranged near the outer periphery of the wafer stage, and the second gas inlet of the wafer stage. Also has a gas exhaust port 31 disposed on the inner peripheral side, and the temperature control means 26 has a gas flow rate introduced from the first gas introduction port 19, a gas flow rate introduced from the second gas introduction port 27, and a gas exhaust port. By controlling the flow rate of the gas discharged from the port 31, the pressure distribution of the heat conducting gas is set arbitrarily.
[Selection] Fig. 2

Description

The present invention relates to a semiconductor manufacturing apparatus, and more particularly to a semiconductor manufacturing apparatus for processing a semiconductor wafer using plasma.

回路 With the increasing integration of semiconductor devices, circuit patterns have continued to be miniaturized, and the required processing dimensional accuracy has become increasingly strict. Under such circumstances, controlling the temperature of the wafer during processing is important. For example, in an etching process that requires a high aspect ratio, in order to realize anisotropic etching, etching is performed while protecting the side walls with a reaction product or an organic polymer. At this time, the amount of the reaction product or the organic polymer attached to the side wall of the protective film changes depending on the temperature of the wafer. Therefore, if the temperature control of the wafer is insufficient, the thickness of the side wall protective film varies among the wafers, and as a result, the etching shape deteriorates. In particular, in a process for processing a large-diameter wafer, the density distribution of the organic polymer serving as the sidewall protective film may be non-uniform near the center and the periphery of the wafer.

In such a case, it is impossible to obtain a uniform etching result only by controlling the temperature on the wafer surface uniformly, and it is necessary to actively control the temperature distribution on the wafer surface.

Patent Literature 1 discloses a method of introducing a thermally conductive gas between a stage supporting a wafer and the wafer to cool the wafer. In this method, the pressure of the thermally conductive gas introduced near the outer periphery of the wafer, which is difficult to cool, is set to be higher than the pressure of the gas introduced into the region inside the wafer, so that the temperature rise near the outer periphery can be further suppressed. It is shown.
JP-A-4-87321

However, in the above-described conventional example, two paths for the flow of the heat conductive gas are required, and the pressure distribution on the wafer surface due to the heat conductive gas introduced from the vicinity of the outer periphery and the heat conductive gas introduced from the inside thereof is quickly increased. It is difficult to obtain a desired pressure distribution.

For example, in the case of controlling the pressure of the opening near the outer periphery and the pressure of the opening inside thereof, immediately after the introduction of the gas, a high pressure distribution on the outer periphery and a low pressure distribution on the inside can be achieved, but within a relatively short time. The pressure in the space between the back surface of the wafer and the surface of the electrode becomes uniform, and it is difficult to keep the pressure near the outer periphery high. If the pressure difference between the area around the outer periphery and the area on the other side is forcibly maintained, the average value of the pressure may increase and the average temperature of the wafer may change.

Further, when the heat conductive gas is introduced from the opening arranged near the outer periphery and exhausted from the opening arranged inside, the inner opening is opened at the same height as the surface of the electrode on which the wafer is loaded. As a result, the conductance from the opening disposed near the outer periphery is reduced, and pressure distribution may be applied to the heat transfer gas.

The present invention has been made in view of the above problems, and provides a semiconductor manufacturing apparatus capable of arbitrarily setting a pressure distribution of a heat conductive gas introduced between a semiconductor wafer and a wafer stage and arbitrarily setting a temperature distribution of the semiconductor wafer. I do.

The present invention employs the following means in order to solve the above problems.

In a semiconductor manufacturing apparatus including plasma generation means for generating plasma in a vacuum processing chamber, a wafer stage for holding a semiconductor wafer on its surface, and temperature control means for controlling the semiconductor wafer to a predetermined temperature, the wafer stage includes a wafer stage. A first gas inlet located near the center, a second gas inlet located near the outer periphery of the wafer stage, and a gas outlet located closer to the inner periphery than the second gas inlet of the wafer stage. The temperature control means controls a gas flow rate introduced from the first gas introduction port, a gas flow rate introduced from the second gas introduction port, and a gas flow rate discharged from the gas exhaust port, thereby providing a heat transfer gas. Is set arbitrarily.

た め Since the present invention has the above configuration, it is possible to provide a semiconductor manufacturing apparatus capable of arbitrarily setting the pressure distribution of the heat conductive gas introduced between the semiconductor wafer and the wafer stage and arbitrarily setting the temperature distribution.

Hereinafter, the best embodiment will be described with reference to the accompanying drawings. 1 is a diagram showing a semiconductor manufacturing apparatus according to an embodiment of the present invention, FIG. 2 is a diagram showing a cross section of the wafer stage shown in FIG. 1, and FIG. 3 is a plan view of the wafer stage. In these figures, 1 is a processing gas introduced into the processing chamber, 2 is a high-frequency power supply, 3 is a coil for applying the high-frequency power supply 2, 4 is a plasma formed in the processing chamber, 5 is a semiconductor wafer, and 6 is a semiconductor wafer. 7 is a clamp for fixing the semiconductor wafer 5, 8 is an electrode electrically connected to the wafer stage, 9 is an insulating plate, 10 is a vacuum chamber, 11 is a flange, 12 is a power supply rod, and 13 is a high frequency power supply. , 14 is an insulating material for insulating the power supply rod from the flange, and 15 is a blocking capacitor.

16 is a refrigerant passage, 17 is a temperature controller for circulating a refrigerant of a predetermined temperature, 18 is a refrigerant passage formed in the wafer stage, 19 is a first gas inlet disposed near the center of the wafer stage, and 20 is a first gas inlet. A first pipe 21 connected to the gas inlet 19 is a protective cover, which protects the outer periphery of the electrode 8 and the wafer stage 6 from plasma. Reference numeral 22 denotes a turbo molecular pump for exhausting the inside of the processing chamber, and reference numeral 23 denotes a dry pump. Reference numeral 24 denotes a first flow controller, which controls the flow rate of the gas introduced from the first gas inlet 19. Reference numeral 25 denotes a first pressure gauge connected to the first pipe 20, and 26 denotes a first flow controller, a second flow controller 29, and an exhaust valve 32 based on measured values of the pressure gauges 25, 30, and 35. Is a control computer that controls the 27 is a second gas inlet formed near the outer periphery of the wafer stage, 28 is a second pipe connected to the second gas inlet 27, 29 is a second flow controller, and a second gas inlet The flow rate of the gas introduced from the port 27 is controlled. Reference numeral 30 denotes a second pressure gauge connected to the second pipe 28. 31 is a gas exhaust port located on the inner peripheral side of the second gas inlet, 32 is an exhaust valve, 33 is a third pipe connected to the gas exhaust port, 34 is a vacuum pump connected to the exhaust port 31, 35 Is a third pressure gauge connected to the third pipe.

As shown in FIG. 1, a processing gas 1 introduced into a processing chamber is in a plasma 4 state by a magnetic field generated by a coil 3 connected to a high frequency power supply 2 and an electric field generated by a high frequency power supply 13. A semiconductor wafer 5 to be processed is loaded on a wafer stage 6 and fixed by a clamp 7. The wafer stage 6 is fixed on the electrode 8 with bolts, and is electrically insulated from the vacuum chamber 10 by the insulating plate 9. The electrode 8 electrically connected to the wafer stage 6 is connected to a high-frequency power supply 13 via a power supply rod 12 and a blocking capacitor 15. Thereby, a bias voltage can be applied to the wafer to effectively draw ions in the plasma into the wafer.

As shown in FIG. 2, a coolant passage 18 for circulating a coolant controlled at a constant temperature by a temperature controller 17 provided outside the processing apparatus is provided inside the wafer stage 6. Thereby, the heat incident on the wafer can be removed by the temperature controller via the wafer stage 6 and the coolant, and the wafer can be cooled.

However, the pressure in the processing chamber is about several Pa, and a sufficient heat transfer coefficient between the wafer and the wafer stage cannot be secured. The first gas inlet 19 and the second gas inlet 27 improve the heat transfer coefficient by introducing a cooling gas (for example, helium gas) between the wafer and the wafer stage.

That is, a first gas inlet 19 is provided at the center of the wafer stage 6, and a first flow controller 24 is connected to the gas inlet via a first pipe 20. In addition, a first pressure gauge 25 is provided downstream of the flow controller 24 for measuring the pressure of the cooling gas flowing into the center of the wafer stage. The measurement result is transmitted to the computer 26. The computer 26 controls the flow controller so that the pressure measured by the first pressure gauge becomes a preset value.

Further, four second gas inlets 27 are provided concentrically near the outer periphery of the wafer stage as shown in FIG. 3, and these gas inlets are provided with a second flow control via a second pipe 28. Device 29 is connected. A second pressure gauge 30 is provided on a pipe downstream of the flow controller to measure the pressure of the cooling gas introduced near the outer periphery of the wafer stage. The measurement result of the second pressure gauge is transmitted to the computer 26. The computer 26 controls the flow controller so that the pressure measured by the second pressure gauge becomes a preset value.

Further, inside the second gas inlet, four outlets 31 for exhausting the cooling gas introduced from the first and second inlets are provided concentrically as shown in FIG. . A vacuum pump 34 is connected to this gas exhaust port through a third pipe 33 via an exhaust valve 32. The third pipe is provided with a third pressure gauge 35 for measuring the pressure near the outlet of the cooling gas. The measurement result of the pressure gauge 35 is transmitted to a computer. The computer 26 controls the exhaust valve 32 so that the pressure measured by the third pressure gauge becomes a preset value.

That is, the pressure of the cooling gas introduced between the back surface of the wafer and the stage can be independently controlled in the vicinity of the center of the stage, the periphery of the stage, and the vicinity thereof. Thereby, the heat transfer coefficient between the wafer and the wafer stage can be changed depending on the region in the radial direction, and the temperature distribution in the wafer surface can be set arbitrarily.

In the plasma processing apparatus including the wafer stage configured as described above, since the etching characteristics in the wafer surface can be controlled, it is possible to perform processing with very high reproducibility.

For example, when aluminum wiring formed on a large-diameter wafer is etched using chlorine gas, the reaction products generated when the aluminum or resist film is etched are re-attached to the side walls of the aluminum wiring and vertical etching is performed. Is realized. This reactive product is generated in the same manner at the center and near the outer periphery of the wafer. However, when the diameter of the wafer increases, the reaction products generated near the center are less likely to be exhausted than the reaction products generated near the outer periphery, so that the concentration of the reaction products at the center of the wafer increases. In such a situation, when etching is performed under the conventional condition in which the temperature in the wafer surface is constant, the etching rate tends to be lower than that in the vicinity of the outer periphery because a large amount of reactive substances adhere to the aluminum wiring near the center of the wafer. Therefore, the finally obtained etching shape is different in the wafer plane.

On the other hand, when the processing apparatus according to the present embodiment is used to perform etching while setting the cooling gas pressure near the periphery to be higher than that near the center of the wafer, the heat transfer coefficient near the periphery of the wafer is improved. The temperature near the outer periphery can be set lower than that near the center. The adhesion of the reaction product is strongly affected by the temperature of the wafer, and the lower the temperature, the easier the adhesion. Therefore, by appropriately setting the temperature in the vicinity of the outer periphery, the amount of reaction products deposited in the vicinity of the outer periphery can be made substantially the same as that in the vicinity of the center, and the etching rate in the wafer surface can be made substantially uniform.

The case where the temperature near the outer periphery of the wafer needs to be set low has been described above, but the present embodiment is also effective in the opposite case. For example, when a plurality of processes are realized by one apparatus, the condition of the plasma may change when the conditions and pressure of the processing gas are changed. For example, when the plasma density near the center of the wafer is higher than that near the outer periphery, only the etching rate near the center increases. In such a case, contrary to the previous example, the temperature near the center of the wafer is set low to increase the adhesion of reaction products near the center and reduce the etching rate near the center, thereby reducing the wafer speed. The in-plane etching rate can be made uniform.

In the present embodiment, the cooling gas is introduced from the vicinity of the center and the outer periphery of the wafer stage, and the cooling gas is exhausted from the inner position near the outer periphery. Can be given. Therefore, it is possible to provide a processing apparatus having good temperature controllability as compared with a case where gas is introduced only from the center and the outer periphery, for example. In addition, since the pressure of the cooling gas near the center and the pressure of the gas near the outer periphery can be controlled independently, the cooling gas is introduced from the gas introduction port arranged near the outer periphery, and from the exhaust port arranged near the center. Unlike a device that exhausts gas, the temperature distribution of the wafer can be controlled to various temperature distributions from a state where the outer periphery is low to a state where the center is low.

As described above, in the present embodiment, the cooling gas introduction port is located at one location at the center of the wafer stage, the concentric circles around the periphery are located at four locations, and the exhaust port is located at the introduction port near the wafer stage periphery. Four concentric circles located inside are provided. However, the inlet and the outlet need not be arranged at the center or concentric circle of the wafer stage. Also, there is no need to provide four inlets or outlets. The positions and numbers of the gas inlets and gas outlets may be determined so that the wafer temperature distribution is appropriate. Further, the shape of the opening of the gas introduction port or the exhaust port does not need to be circular, but may be any shape, for example, a slit shape. Further, the opening may have a structure filled with a porous chamber material.

Next, a second embodiment of the present invention will be described with reference to FIGS. FIG. 4 is a plan view of the wafer stage according to the present embodiment, and FIG. 5 is a sectional view of the wafer stage. In these figures, 36 is a groove region provided concentrically on the surface of the wafer stage, 37 is a gas inlet provided in a groove region near the center of the wafer stage, and 38 is a groove region formed near the outer periphery of the wafer stage. Gas inlet 39, a gas exhaust port provided inside the inlet near the outer periphery of the wafer stage, a groove region 40 provided radially on the surface of the wafer stage, and 41 provided concentrically on the surface of the wafer stage. This region is in contact with the wafer and supports the wafer.

In the first embodiment, the gas inlet and the gas outlet are simply opened on the surface of the wafer stage. In this configuration, since gas does not easily flow in the circumferential direction, a pressure distribution may be generated in this direction. In a process that is sensitive to the wafer temperature distribution, a temperature difference based on the circumferential pressure distribution may become a problem. To address this problem, it is conceivable to increase the number of gas inlets and outlets in the circumferential direction.However, this method increases the number of pipes connected to the gas inlets and outlets. Routing becomes complicated.

In this embodiment, as described above, the concentric groove region 36 and the radially extending groove region 40 are provided on the surface of the wafer stage, one gas inlet 39 is provided in the center groove region, and the groove provided near the outer periphery is provided. Four gas inlets 38 are provided in the area, and four exhaust ports 39 are provided in the inner area. If the depth of the groove region is too large, the heat transfer coefficient between the wafer and the stage decreases, and the temperature distribution in the wafer surface becomes uneven. Therefore, the depth of the groove region is preferably suppressed to about 1 mm or less.

With such a configuration, a favorable temperature distribution can be obtained by equalizing the circumferential pressure distribution between the wafer back surface and the wafer stage.

Next, a third embodiment of the present invention will be described with reference to FIGS. FIG. 6 is a view showing a semiconductor manufacturing apparatus according to the embodiment of the present invention, and FIG. 7 is a sectional view of a wafer stage. In these figures, reference numeral 42 denotes a dielectric film provided on the surface of the wafer stage, and reference numeral 36a denotes a groove region provided concentrically on the surface of the dielectric film 42. Reference numeral 41a denotes a convex region provided concentrically on the surface of the dielectric film 42, and this portion contacts the wafer and supports the wafer. Further, a radial groove region (not shown) can be provided on the surface of the dielectric film. Reference numeral 43 denotes a DC power supply for supplying a power supply for electrostatically chucking the wafer to the wafer stage 6. 44 is a power supply protection coil. In the drawings, the same portions as those shown in FIGS. 1 to 3 are denoted by the same reference numerals, and description thereof will be omitted.

In the present embodiment, a structure is provided in which a dielectric film 42 having groove regions formed in the circumferential direction and the radial direction is provided on the surface of the wafer stage. A DC power supply 43 is connected to the wafer stage via a power protection coil 44. When the voltage of the DC power supply 43 is applied to the wafer stage 6 in a state where the plasma is ignited, the dielectric film 42 is in contact with the vacuum chamber 10 through the plasma 7 which is at the ground potential. A DC voltage is applied. Thus, the wafer 7 is attracted to the wafer stage 6 by the Coulomb force.

If the thickness of the dielectric film 42 is too large, the attraction force is insufficient. If the depth of the groove provided in the dielectric film is set to about 1 mm or less as described above, the temperature distribution in the wafer surface does not deteriorate. In this embodiment, the wafer can be fixed without providing a clamp or the like. Therefore, a processing device with a high yield can be provided without the element being destroyed by foreign matter generated from the contact portion or the like. Further, compared with a case where the wafer is fixed to the stage by a clamp, the wafer is more closely adhered to the surface of the wafer stage at the suction portion, and the heat transfer coefficient is improved, so that the controllability of the wafer temperature is further improved.

Next, a fourth embodiment of the present invention will be described with reference to FIG. FIG. 8 is a diagram showing a semiconductor manufacturing apparatus according to the embodiment of the present invention. In the figure, 45 is a through hole penetrating the wafer stage 6 and the dielectric film 42, 46 is a thermometer such as a fluorescent thermometer inserted into the through hole 45, and the thermometer is arranged so as to be in contact with the back surface of the wafer. The detection output is supplied to the computer 26. In the figure, the same parts as those shown in FIG. 6 are denoted by the same reference numerals, and description thereof will be omitted.

The computer 26 receives the output of the thermometer, controls the flow controllers 24 and 29 and the opening of the exhaust valve 32, and controls the temperature of the wafer to a set value. The thermometer may measure the temperature of a place where the temperature of the wafer can be predicted, instead of directly measuring the temperature of the wafer.

As described above, according to the embodiment, the cooling gas is introduced from the gas introduction ports provided near the center and the outer periphery, and the gas is exhausted from the exhaust port provided in the inner region on the outer periphery. The pressure of the cooling gas introduced between the wafer being processed and the wafer stage can be arbitrarily set near the center and the periphery. For this reason, the temperature distribution in the wafer surface can be arbitrarily changed. Thus, the etching rate in the wafer surface can be made uniform from the center to the vicinity of the outer periphery, and a processing apparatus with good reproducibility can be provided.

In addition, when the gas inlet and exhaust ports are provided in gas grooves arranged concentrically, unnecessary circumferential pressure distribution can be suppressed as much as possible, so that the temperature distribution in the wafer surface is further improved, A processing device with good reproducibility can be provided.

Further, if a dielectric film is provided on the surface of the wafer stage, a potential difference is generated between the wafer and the wafer stage, and the wafer is fixed to the stage by Coulomba, a clamp is not required on the wafer surface. As a result, it is possible to prevent element destruction or the like due to foreign matter adhering to the wafer surface during processing, and to provide a processing apparatus with a high yield. Further, the thermal contact is improved as compared with the case where the wafer is fixed by the clamp, so that the temperature rise of the wafer can be further suppressed, and a processing apparatus with more controllability can be provided.

Furthermore, a thermometer for measuring the temperature of the wafer is provided on the wafer stage, and the flow rate and pressure of the heat conductive gas are controlled based on the information of the thermometer, thereby providing a processing apparatus having excellent controllability of the wafer temperature. Can be provided.

FIG. 1 is a diagram illustrating a semiconductor manufacturing apparatus according to a first embodiment of the present invention. FIG. 2 is a diagram showing a cross section of the wafer stage shown in FIG. 1. FIG. 3 is a plan view of a wafer stage. FIG. 6 is a diagram illustrating a semiconductor manufacturing apparatus according to a second embodiment of the present invention. FIG. 3 is a plan view of a wafer stage. FIG. 8 is a diagram illustrating a semiconductor manufacturing apparatus according to a third embodiment of the present invention. FIG. 3 is a plan view of a wafer stage. It is a figure showing a semiconductor manufacturing device concerning a 4th embodiment of the present invention.

Explanation of reference numerals

DESCRIPTION OF SYMBOLS 1 Processing gas 2, 13 High frequency power supply 3 Coil 4 Plasma 5 Semiconductor wafer 6 Wafer stage 7 Clamp 8 Electrode 9 Insulating plate 10 Vacuum chamber 11 Flange 12 Feeding rod 14 Insulating material 15 Blocking capacitor 16 Pipe 17 Temperature regulator 18 Refrigerant passage 19 1 gas inlet 20 first pipe 21 protective cover 22 turbo molecular pump 23 dry pump 24 first flow controller 25 first pressure gauge 26 control computer 27 second gas inlet 28 second pipe 29 2 flow controller 30 second pressure gauge 31 gas exhaust port 32 exhaust valve 33 third pipe 34 vacuum pump 35 third pressure gauge 36, 40 groove area 37, 38 gas inlet port 39 gas exhaust port 41 convex area 42 Dielectric film 43 DC power supply 44 Power supply protection coil 45 Through hole 46 Thermometer

Claims (1)

In a semiconductor manufacturing apparatus comprising: a plasma generation unit that generates plasma in a vacuum processing chamber; a wafer stage that holds a semiconductor wafer on the surface thereof; and a temperature control unit that controls the semiconductor wafer to a predetermined temperature. A first gas inlet port located near the center of the wafer stage, a second gas inlet port located near the outer periphery of the wafer stage, and a gas outlet port located on the inner peripheral side of the second gas inlet of the wafer stage. Wherein the temperature control means controls a gas flow rate introduced from the first gas introduction port, a gas flow rate introduced from the second gas introduction port, and a gas flow rate discharged from the gas exhaust port. Semiconductor manufacturing equipment.

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