JP2000216140A - Wafer stage and wafer treating apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a wafer stage which controls the temp. distribution over a wafer being treated as desired at a high response performance. SOLUTION: In a wafer stage mounting a wafer 9 being treated, a plurality of independent refrigerant passages 20, 21 are provided, pipings 22-25 are connected to the passages 20, 21 through valves 29, 30 capable of adjusting the flow rate of a refrigerant every passage, and the opening degrees of the valves 29, 30 are adjusted to adjust the flow rates of the refrigerant. Thus, the temp. distribution of the wafer 9 being treated can be controlled by adjusting only the opening degrees of the valves 29, 30 connected to the pipings 24, 25 and hence the temp. can be controlled at a high response performance and a low cost.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a semiconductor manufacturing technique. In particular, the present invention relates to a stage for controlling the temperature of a wafer during processing of the wafer in a semiconductor manufacturing apparatus.

[0002]

2. Description of the Related Art With the recent increase in the degree of integration of semiconductor devices, circuit patterns are becoming finer, and the required processing dimensional accuracy is becoming increasingly severe. In such a situation, the temperature control of the wafer being processed becomes very important. For example, in an etching process that requires a high aspect ratio, a process of performing etching while protecting the side walls with an organic polymer to realize anisotropic etching has been realized. Varies with temperature. Therefore, if the temperature control of the wafer during processing is insufficient, the side wall protective film varies within the wafer surface, resulting in a problem that the etching shape becomes non-uniform.

A method for coping with such wafer temperature control during processing is disclosed in, for example, Japanese Patent Application Laid-Open No. 9-298192. In this disclosed example, a method of changing a set temperature of a wafer in an etching process when, for example, materials having different vapor pressures of reactive products are etched, or when different etching conditions such as just etching and over etching are required. It has been disclosed. As the method, the refrigerant flowing inside the sample stage is a liquefied gas or gas, and the temperature control is performed by adjusting the flow rate of the refrigerant by flow rate adjusting means provided in a plurality of pipes having different diameters provided upstream of the sample stage. Discloses a method of performing a response with high responsiveness.

[0004]

However, this method is an effective method for controlling the temperature of the wafer during processing with good responsiveness, but arbitrarily sets the temperature distribution in the wafer surface during processing. It is not possible to realize a temperature distribution such that the temperature near the center of the wafer is higher than the temperature near the outer periphery of the wafer.

[0005] Such a request arises, for example, when a reaction product generated by the etching process adheres to the processing surface again. In other words, the reaction products are re-adhered to the processing surface and cause a decrease in the etching rate. However, the reaction products tend to be distributed more near the center of the wafer than near the periphery of the wafer. As a result, the etching rate is low and the etching shape varies within the wafer surface.

As a method of improving this, it is effective to raise the temperature near the center of the wafer as compared with the vicinity of the outer periphery, thereby suppressing the reattachment of reactive products to the etched surface.

In the plasma etching, the plasma may etch a vacuum chamber wall or a reaction product adhered to the vacuum chamber wall, and the generated reaction product may adhere again to the etching surface of the wafer. In some cases, a region where a reactive product is likely to adhere may change depending on the positional relationship between the wafer stage and the vacuum chamber. Such a problem is expected to become more and more important in order to realize uniform etching, particularly with the recent increase in wafer diameter.

A first object of the present invention is to provide a wafer stage capable of controlling the temperature distribution of a wafer during processing with good responsiveness.

A second object of the present invention is to provide a wafer stage capable of controlling the temperature distribution of a wafer during processing with high accuracy.

A third object of the present invention is to provide a wafer stage which can efficiently control the temperature distribution of a wafer being processed even in a vacuum.

A fourth object of the present invention is to provide a wafer processing apparatus provided with a wafer stage having good temperature controllability of a wafer during processing.

[0012]

A first object of the present invention is to provide a plurality of independent coolant channels inside a wafer stage on which a wafer being processed is loaded, and to provide a coolant flow rate for each of these independent channels. Can be achieved by connecting piping via a valve that can control the flow rate of the refrigerant by adjusting the opening degree of the valve.

The second object is to measure the temperature of a wafer during processing or the temperature of a wafer stage, and adjust the opening degree of a valve provided in a pipe based on the measurement result of the temperature to control the flow rate of the refrigerant. This can be achieved by feedback control to adjust.

The above third object can be achieved by introducing helium gas into the back surface of the wafer being processed. Further, it is possible to achieve this more efficiently by providing a dielectric film on the surface of the wafer stage, giving a potential difference between the dielectric film and the wafer, and fixing the wafer by the electrostatic force of the electric charge stored during this time. Further, if a helium gas introduction groove is provided on the front surface of the wafer stage, the helium gas can efficiently spread to the front surface of the back surface of the wafer, so that it can be achieved more efficiently.

The fourth object can be achieved by providing a wafer processing apparatus having a wafer stage capable of controlling a temperature distribution in a wafer surface during processing.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings.

FIGS. 1 to 3 show a first embodiment of the present invention. FIG. 1 is a cross-sectional view of the first embodiment of the present invention, FIG. 2 is a view of the aluminum electrode of the first embodiment viewed from the back surface, and FIG. 3 has a wafer stage of the first embodiment of the present invention. This is an example applied to a magnetic field microwave plasma processing apparatus.

First, an application example of the first embodiment will be described with reference to FIG. A quartz tube 14 is set in the air space 3, and a wafer stage 8 is arranged in a vacuum processing chamber 1 formed by the quartz tube 14 to fix a wafer 9. First, the vacuum processing chamber
A processing gas 13 is introduced into 1 and kept at a constant pressure. The processing gas enters a plasma state 7 due to the interaction between the microwave 5 generated by the microwave transmitter 19 and introduced through the waveguide 4 and the coil 6 attached around the microwave resonance box 2. The processing (here, the etching processing) is performed by exposing the wafer to the high-frequency power supply 10 connected via the capacitor 18 to control the incidence of ions and the etching state. Fifteen
Represents exhaust of excess processing gas and reaction products, and is connected to a vacuum pump (not shown here).

Next, the wafer stage, which is a feature of the present invention, will be described with reference to FIGS. As described above, the wafer being processed is heated by the incidence of electrons and ions from the plasma, so that it is necessary to control the temperature of the wafer to achieve uniform etching. For this purpose, a coolant is allowed to flow inside the wafer stage for cooling, and a helium gas is introduced to the back surface of the wafer to improve heat transfer between the wafer and the aluminum stage.

First, the wafer stage 8 is placed on the base 11.
It has a structure in which an aluminum electrode 16 is screwed through an O-ring 12. In the aluminum electrode 16, channels 20 and 21 for flowing a coolant therein are dug. This flow path includes a flow path 20 for cooling the vicinity of the center of the aluminum electrode,
2 independent channels 21 for cooling the vicinity of the outer periphery of the aluminum electrode
Has a system. Refrigerant introduction pipes 22 and 23 and discharge pipes 24 and 25 are connected to the respective flow paths. These pipes are connected to the discharge of a single temperature controller 26 for controlling the temperature of the refrigerant grounded to the outside. The outlet 27 and the suction port 28 are connected to one pipe so as to be joined.

The discharge pipes 24 and 25 are provided with valves 29 and 30 for adjusting the flow rate. By adjusting the opening of the valve, the flow rate of the refrigerant flowing through each flow path can be adjusted, and the temperature distribution of the wafer during processing can be adjusted.

That is, since the ability to transport heat incident on the wafer is different in the plane of the wafer stage, the temperature changes near the center and the periphery of the wafer.

A helium introduction tube 31 is provided near the center of the wafer stage so that helium can be introduced from the outside while controlling the flow rate.

Thus, the heat incident on the wafer can be efficiently transmitted to the wafer stage. However, a clamp 3 for mechanically pressing the outer peripheral portion of the wafer so that the wafer does not slip due to the pressure of the helium gas during processing.
2 are provided at four locations on the outer periphery. A cover 33 made of ceramics is provided for preventing the wafer stage from being directly exposed to the plasma and for roughly positioning the wafer.

With this configuration, the wafers are loaded on the wafer stage and processed. For example, if the opening degrees of the valves 29 and 30 provided in the discharge pipe are made the same, the flow rate of the refrigerant flowing through each flow path becomes the same. The inside wafer has a substantially uniform temperature distribution. However, for example, the opening degree of the valve 29 of the discharge pipe 24 connected near the center of the wafer stage is reduced,
When the flow rate of the coolant is reduced, the cooling ability of the heat incident near the center of the wafer becomes lower than the cooling ability of the heat incident near the outer periphery of the wafer, so that the temperature becomes higher near the center of the wafer. Such a temperature distribution is effective particularly when the reaction products generated by etching are large near the center of the wafer.

That is, the reaction products are re-attached to the processing surface and cause a reduction in the etching rate. However, since the reaction products are harder to re-adhere by increasing the temperature near the center of the wafer than the vicinity of the outer periphery. It is.

As described above, an independent refrigerant flow path is provided inside the wafer stage on which the wafer being processed is loaded, and the flow rate of the refrigerant flowing through this flow path is adjusted by the opening degree of a valve provided in the refrigerant pipe to adjust the flow rate of the wafer. If the temperature distribution in the plane is controlled, the temperature distribution of the wafer during processing can be controlled.

Further, since the temperature distribution can be controlled by adjusting only the flow rate of the refrigerant without changing the temperature setting of the refrigerant temperature controller, the temperature distribution control with a very responsive property can be achieved. Furthermore, the temperature distribution of the wafer can be controlled by adjusting the opening degree of a valve provided in the refrigerant pipe, and it is not necessary to provide a temperature controller for each of a plurality of independent refrigerant channels, and the temperature can be controlled by one temperature controller. Since distribution control can be performed, costs can be kept low.

FIG. 4 shows a second embodiment of the present invention. In the present embodiment, fluorescent thermometers 36 and 37 for penetrating the base 34 and the aluminum electrode 35 and measuring the temperature on the back surface of the wafer are provided at two places near the center of the wafer and near the periphery of the wafer. The temperature of the wafer during processing is measured by the fluorescence thermometer, and the arithmetic circuit 38 controls the valve 2 provided on the discharge pipes 24 and 25.
Appropriate openings 9 and 30 are calculated, and the valve opening mechanism 39 is feedback-controlled. At this time, the temperature distribution necessary for realizing the desired processing shape is determined in advance by performing experiments and the like on the correlation between the temperature distribution and the processing shape when processing the wafer with the apparatus to which the wafer stage of this embodiment is applied. It should be left.

In the wafer stage configured as described above, the temperature distribution of the wafer being processed can be controlled with very high responsiveness without changing the temperature setting of the coolant temperature controller, and the temperature of the wafer being processed can be controlled. Since the distribution can be kept optimal, highly reproducible and highly accurate temperature control can be performed.

In this embodiment, the temperature distribution of the wafer is measured directly by a fluorescent thermometer penetrating the base and the aluminum electrode. However, the present invention is not limited to this. The temperature may be measured by embedding a thermocouple in the base material or the base, or the temperature on the return side of the refrigerant may be measured by a thermocouple or the like. Even in these cases, as described above, the correlation between the temperature at the measurement point and the temperature distribution of the wafer being processed may be grasped in advance.

FIG. 5 shows a third embodiment of the present invention. In this embodiment, unlike the first and second embodiments, one temperature controller 40, 41 is connected to each of two independent flow paths 20, 21 in the aluminum electrode. In other words, the flow path 21 near the outer periphery of the aluminum electrode 16 is connected to the introduction pipe 42 from the temperature controller 40.
Through the discharge pipe 43 and discharge the refrigerant through the discharge pipe 43.

The flow path 20 near the center of the aluminum electrode 16
The refrigerant flows from the temperature controller 41 through the introduction pipe 44 and is discharged through the discharge pipe 45. The flow rate of the refrigerant flowing through each flow path is adjusted by adjusting the degree of opening of the valves 46 and 47. The temperature of the refrigerant flowing out of the two temperature controllers may be set so that the temperature distribution of the wafer becomes a desired one.

If it is necessary to change the temperature distribution as a result of monitoring the temperature of the wafer being processed, the flow rate of the refrigerant is adjusted by operating the valve in the same manner as in the second embodiment so that the temperature distribution can be improved with good responsiveness. Can be changed.

Therefore, in the wafer stage configured as described above, the temperature distribution in the wafer surface can be controlled with good responsiveness and immediately after the start of processing. Further, even when the heat input to the wafer is not so large, the temperature distribution in the wafer surface can be increased.

FIG. 6 shows a fourth embodiment of the present invention. In the present embodiment, the surface of the aluminum electrode 48 is made of alumina (Ai2O3).
And a mixture of titania (TiO2) are applied as a dielectric film 49 by thermal spraying under a reduced-pressure atmosphere to have a function of electrostatic attraction. The surface 52 of the dielectric film is polished to a surface roughness of about 1 μm as a center line average roughness, and the base 11 is connected to an external DC power supply 50 so that a DC voltage can be applied.
Since the aluminum electrode 48 is electrically connected to the base 11, the wafer 9 is loaded on the surface of the dielectric film 49 and the plasma 7
When a DC voltage is applied to the aluminum electrode in a state of being exposed, the dielectric film is charged, and the wafer can be fixed by suction by electrostatic force.

Therefore, even when a helium cooling gas for improving the heat transfer between the wafer and the dielectric film is introduced, foreign matter is generated from the contact surface with the wafer, which causes a decrease in the yield of semiconductor manufacturing. There is no need for a clamp.

If an electrostatic chuck is used to fix the wafer as in the present embodiment, for example, even if the wafer is warped, the warp is corrected and the wafer is fixed. This is advantageous in that the thermal contact with the back surface of the wafer is strengthened and the cooling efficiency is improved.

Therefore, with the wafer stage configured as described above, in addition to the effects expected from the first to third embodiments, finer processing can be realized, and the cooling efficiency of the wafer during processing is improved. Therefore, there is no need to provide a mechanical clamp or the like on the front surface side of the wafer, and the effect of suppressing contamination by foreign matter can be expected.

In this embodiment, a mixture of alumina and titania is formed on the surface of the aluminum electrode by thermal spraying.
This is not always necessary, and any other material may be used as long as the material has dielectric properties, or a ceramic sintered body fixed with an adhesive or the like may be used.

The electrostatic attraction device according to the present embodiment is configured as a so-called monopolar electrostatic attraction device for applying a voltage of either positive or negative polarity to the dielectric film.
A so-called bipolar structure may be adopted in which positive and negative polar voltages are applied to the dielectric film to attract the wafer. In this case, the structure of the electrostatic attraction device becomes complicated, but the effect of improving usability can be expected because the attraction and fixing can be performed arbitrarily without any other means for applying a potential to the wafer, such as plasma. it can.

FIG. 7 shows a fifth embodiment of the present invention. In the present embodiment, the gas grooves 51 for efficiently flowing helium into the surface of the dielectric film of the fourth embodiment are arranged concentrically. With such a configuration in which the gas grooves are provided, the helium gas introduced from the gas inlet uniformly spreads to the vicinity of the outer periphery, so that the entire back surface of the wafer can be more efficiently cooled.

In addition, the cooling capacity of the adsorbed portion is higher than that of the portion where the gas is actually adsorbed and the gas groove, and the cooling capacity of the gas groove portion also differs depending on the depth of the gas groove. More efficient temperature distribution can be realized in the plane.

As described above, the wafer stage of the present invention can control the temperature distribution of the wafer being processed with good responsiveness. Therefore, a wafer processing apparatus equipped with the present apparatus can provide an apparatus with very good temperature control. it can.

[0045]

As described above, according to the present invention, a plurality of independent coolant channels are provided inside a wafer stage on which a wafer being processed is loaded, and the flow rate of the coolant is controlled for each of the independent channels. By connecting a pipe via an adjustable valve, adjusting the opening of the valve and adjusting the flow rate of the coolant, it becomes possible to control the temperature distribution of the wafer during processing. Also, since the temperature of the wafer during processing or the temperature of the wafer stage is measured, and based on the measurement result of the temperature, feedback control is performed so as to adjust the opening degree of the valve provided in the pipe and adjust the flow rate of the refrigerant. Thus, it is possible to provide a wafer stage having very good temperature controllability of a wafer during processing. Further, by adopting a configuration in which helium gas is introduced into the back surface of the wafer being processed, a wafer stage that can more effectively control the temperature of the wafer can be provided, and the helium gas can be evenly distributed to the back surface of the wafer. If a gas groove is provided, improvement in cooling performance can be expected. Also, if a dielectric film is provided on the surface of the wafer stage, a potential difference is applied between the dielectric film and the wafer, and the wafer is fixed by the electrostatic force of the electric charge stored between the dielectric film and the wafer, the temperature distribution of the wafer is more efficiently reduced. In addition to control, a clamp or the like that mechanically suppresses the processing surface of the wafer is not required, and contamination due to generation of foreign matter can be prevented. Furthermore, if the wafer stage of the present invention is applied to a processing apparatus, it is possible to provide an apparatus having excellent temperature controllability of a wafer during processing.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a first embodiment of the present invention.

FIG. 2 is a view of the aluminum electrode according to the first embodiment of the present invention as viewed from the back surface.

FIG. 3 is an explanatory diagram in which the first embodiment of the present invention is applied to a magnetic field microwave plasma processing apparatus.

FIG. 4 is an explanatory diagram of a second embodiment of the present invention.

FIG. 5 is an explanatory diagram of a third embodiment of the present invention.

FIG. 6 is an explanatory diagram of a fourth embodiment of the present invention.

FIG. 7 is an explanatory diagram of a fifth embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Vacuum processing chamber, 2 ... Microwave resonance box, 3 ... Atmospheric space, 4 ... Waveguide, 5 ... Microwave, 6 ... Coil, 7 ... Plasma, 8 ... Wafer stage, 9 ... Wafer, 10 ... High frequency power supply , 11 base, 12 O-ring, 13 processing gas, 14 quartz tube, 15 exhaust, 16 aluminum electrode, 1
7: screw, 18: condenser, 19: microwave transmitter, 20: flow path, 21: flow path, 22: introduction pipe, 23 ...
Inlet piping, 24 ... discharge piping, 25 ... discharge piping, 26 ... temperature controller, 27 ... discharge port, 28 ... suction port, 29 ... valve, 3
0: valve, 31: helium introduction tube, 32: clamp,
33 ... cover, 34 ... base, 35 ... aluminum electrode, 36
... Fluorescence thermometer, 37 ... Fluorescence thermometer, 38 ... Calculation circuit, 3
9: valve opening adjustment mechanism, 40: temperature controller, 41: temperature controller, 42: introduction pipe, 43: discharge pipe, 44: introduction pipe,
45 ... discharge pipe, 46 ... valve, 47 ... valve, 48 ...
Aluminum electrode, 49: dielectric film, 50: DC power supply, 51: gas groove, 52: surface of dielectric film.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Saburo Kanai 794, Higashi-Toyoi, Kazamatsu-shi, Yamaguchi Prefecture F-term in the Kasado Plant of Hitachi, Ltd. CA06 5F031 CA02 HA16 HA24 HA38 HA39 JA46 JA51 MA28 MA32 NA04 PA26 5H323 AA40 BB01 BB04 BB20 CA06 CB23 CB25 CB33 CB35 CB43 DA04 DB15 EE01 FF01 FF10 GG16 KK05 MM06

Claims (8)

[Claims] In a wafer stage for loading a semiconductor wafer and processing the semiconductor wafer, a plurality of independent coolant channels are provided inside the wafer stage. An introduction pipe for introducing the refrigerant and a discharge pipe for discharging the refrigerant are provided, and one or both of the introduction pipe and the discharge pipe are provided with a valve capable of controlling the flow rate of the refrigerant by adjusting the opening degree. A wafer stage which is connected to a temperature controller for controlling the temperature of the refrigerant and controls the temperature of the wafer being processed by adjusting the flow rate of the refrigerant by adjusting the opening of the valve. 2. The wafer stage according to claim 1, wherein the opening of the valve is adjusted by feedback control based on a result of measuring a temperature of the wafer stage or a temperature of a wafer being processed. Wafer stage. 3. The wafer stage according to claim 1, wherein the temperature of the refrigerant flowing in the introduction pipe connected to the independent flow path is the same. 4. The wafer stage according to claim 1, wherein the temperature of the refrigerant flowing through the introduction pipe connected to the independent flow path is set to a different temperature for each of the introduction pipes. Characterized wafer stage. 5. The wafer stage according to claim 1, wherein a dielectric film is provided on a surface of the wafer stage.
A wafer stage, wherein a potential difference is applied between the dielectric film and the wafer, and the wafer is fixed by electrostatic force of charges stored between the dielectric film and the wafer. 6. The wafer stage according to claim 1, wherein a heat conductive gas is introduced into the back surface of the wafer. 7. The wafer stage according to claim 1, wherein a gas groove for a cooling gas is provided on a surface of the stage on which the wafer is mounted. 8. A wafer processing apparatus comprising the wafer stage according to claim 1 and performing processing while controlling the temperature of a wafer loaded on the wafer stage.