JP2951903B2 - Processing equipment - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a processing apparatus for performing processing such as dry etching, vapor deposition, and sputtering on a substrate such as a semiconductor wafer. 2. Description of the Related Art For example, when vapor deposition or sputtering is performed as a film forming step in a manufacturing process of a semiconductor device, it is necessary to obtain a good film quality having an appropriate particle diameter, reflectance, specific resistance and hardness. It is necessary to appropriately control the substrate temperature during baking of the substrate and during film formation. In particular, the particle diameter and the reflectance are greatly affected by the temperature of the substrate during film formation. Also, when a resist pattern is formed on the film by exposure and development, and the film is etched according to the resist pattern by dry etching, it is necessary to control the temperature of the substrate. This is because by controlling the temperature of the substrate, it is possible to prevent the resist from being thermally damaged due to the poor heat resistance of the resist and to etch a faithful pattern. However, even if the temperature of the substrate is controlled to be the same as that of the substrate support, the thermal contact between the substrate and the support in a vacuum is not sufficient. It is difficult to control. In view of the above, conventionally, a substrate and a substrate support table are used.
In order to increase the thermal contact between the surfaces, there have been proposed methods of mechanically pressing the substrate against the support, or attracting the substrate to the support by electrostatic force. However, even with such a method, the thermal contact between the two surfaces of the substrate and the support base largely depends on gas molecules interposed between the two surfaces, and the exchange of heat between the pure solids depends on the above-described pressing. Since the pressure is about negligibly small compared to the exchange of heat by gas molecules, a sufficient effect has not been obtained. Japanese Patent Application Laid-Open No. Sho 56-103442 discloses a device for increasing thermal contact by interposing gas molecules between a substrate and a support. [0007] As shown in FIG. 6, the substrate temperature control unit in this apparatus is provided on a support base 5 via a spacer 9.
Are closely arranged and supported by several clips 4.
The support table 5 is provided with a temperature control device 6 having a cooling or heating mechanism. The processing chamber 1 is evacuated through the exhaust port 2 so that the pressure becomes about 1 Pa. At the same time, argon is introduced from the gas inlet 7, and this gas flows between the temperature controller 6 and the substrate 3,
It flows into the processing chamber 1 as shown by an arrow 8. At this time, the pressure in the space 10 between the substrate 3 and the temperature control device 6 is 10 to
It is controlled to be 100 Pa. Therefore, the temperature of the substrate 3 is controlled by the heat transfer of the intervening gas having a pressure of about 100 Pa flowing out of the temperature control device 6. [0010] For example, a diameter of 100
When controlling the temperature of a silicon substrate having a thickness of 0.45 mm and a thickness of 0.45 mm, the time constant is as long as about 20 seconds. In such a situation, when dry etching with an applied power of 500 W is performed, the temperature difference between the gas flowing out of the temperature control device and the surface of the silicon substrate becomes as high as 130 ° C., and the resist is thermally damaged. Can not do. In view of the above circumstances, it is an object of the present invention to provide an etching, film forming, and baking process for manufacturing a semiconductor device.
It is an object of the present invention to provide a processing apparatus capable of effectively controlling a substrate temperature during processing so as to perform good processing. In order to achieve the above object, according to the present invention, a processing chamber provided with an exhaust means for evacuating the inside of the processing chamber, and an upper surface on which the substrate to be processed is placed and which is installed inside the processing chamber, are substantially formed. Substrate electrode means coated with an insulator over the entire surface, voltage applying means for applying a voltage to the substrate electrode means,
A heat transfer gas supply means for supplying a heat transfer gas between the insulating material of the substrate and the substrate electrode means placed on the substrate electrode means, a gas supply means for supplying a gas into the processing chamber A counter electrode means disposed inside the processing chamber so as to face the substrate electrode means, and a high-frequency power application means for applying high-frequency power to the counter electrode means, wherein the evacuation means evacuates to a vacuum. Plasma generated between the counter electrode means and the substrate electrode means by applying high frequency power to the counter electrode by the high frequency power applying means in a state where gas is supplied from the gas supply means into the processing chamber. When the substrate to be processed placed on the substrate electrode means is processed by the heat transfer gas supply means,
Between the substrate and the insulator of the substrate electrode means
Surface is formed with surface roughness less than mean free path of heat transfer gas
The insulator of the substrate electrode means the target substrate by the heat transfer gas supply unit together with the electrostatically adsorbed over the ho substrate to be processed URN whole surface by a voltage applied by said voltage applying means to the insulator The heat transfer gas is supplied to cool the substrate to be processed. In order to reduce the temperature difference between the substrate and the electrode means and increase the response speed of temperature control of the substrate, the amount of heat flowing per unit temperature difference between the substrate and the electrode means per unit time (hereinafter referred to as unit) It is necessary to increase the heat flow.)
To increase the unit heat flow, increase the pressure and simultaneously
The distance between the faces must be less than the mean free path of the gas under the pressure. The substrate temperature during processing varies with time according to the following equation: (1) Tw = (1-exp (-kt / C)) Qi / k +
To where Tw is the substrate temperature, C is the heat capacity of the substrate, k is the unit heat flow, Qi is the constant amount of heat applied to the substrate per unit time during processing, To is the temperature of the electrode means, t is time, and t is time.
At 0.0, Tw = To. Further, when the temperature of the electrode means is at the steady value To and the initial temperature of the substrate TwoｏTo, the following equation is satisfied. (2) Tw = (Two−To) exp (−kt / C) +
In all cases, the response speed of the temperature control of the substrate is:
It depends only on the heat capacity C of the substrate and the unit heat flow k between the two surfaces. The value of C is a value specific to the substrate, for example, 100 m in diameter.
m, about 6.2J · with a silicon substrate 0.45mm thick
K ~ ¹ . Therefore, in order to reduce the temperature difference between the base and the electrode means and increase the response speed of temperature control of the base, it is necessary to increase the unit heat flow. FIG. 5 shows actual measured values showing how the unit heat flow rate changes when nitrogen is interposed between the two surfaces and the pressure is changed. The base was covered with silicon, the surface was covered with thin silicon oxide, and polished aluminum was used as a support material, the surface was sufficiently washed, and a load of 1 kg per 100 mm in diameter was applied between the two surfaces. . The curve is close to a straight line passing through the origin, which proves that under these conditions heat transfer purely between solids is negligible. That is, even if there is mechanical contact between the two surfaces of the solid, most of the thermal contact is due to gas interposed between the two surfaces. Further, it can be seen that when the pressure of the intervening gas is made larger than the value of 100 Pa in the conventional apparatus, the unit heat flow rate increases. The above measured values are based on the following theoretical formula. That is, the amount of heat “dQ / dt” that passes between two surfaces per unit time follows the following equation. (3) dQ / dt = k ₁ (Tw−To) p (e≪λ) (4) dQ / dt = k ₂ (Tw−To) e (e≫λ) where k ₁ and k ₂ are constants , Tw, and To are the temperatures of the substrate and the support material, e is the distance between the two surfaces, p is the pressure of the intervening gas, and λ is the mean free path under the pressure. This equation shows that under low pressure and long enough mean free path,
“DQ / dt” is proportional to p, and indicates that “dQ / dt” is proportional to e when the pressure is high and the mean free path is sufficiently short. Therefore, the unit heat flow can be increased by providing a mechanism for increasing the pressure of the gas interposed between the two surfaces and reducing the distance between the two surfaces to about the mean free path under the pressure. By the way, in the conventional device, p is 1
The mean free path λ of Ar is about 50
μm. Therefore, it is desirable to reduce the interval to about 50 μm, but as shown in FIG.
Due to the pressure difference a, the central portion of the substrate 3 expands as indicated by reference numeral 11. For example, in the case of a silicon wafer having a diameter of 100 mm and a thickness of 0.45 mm, the bulge amount at the center reaches 150 μm due to a pressure difference of 100 Pa. Therefore, the unit heat flow cannot be increased even if the pressure is increased beyond the mean free path of 50 μm. Embodiments of the present invention will be described below with reference to the drawings. First, the principle of temperature control is shown in FIG.
It will be described based on. The support 17 of the substrate 19 and the substrate 1
In a substrate temperature control device having a holding means 23 for holding the substrate 9 and a gas introduction means 52 for introducing a gas into the space 20 formed by the substrate 19 and the support 17, A mechanism for reducing the distance of the gas below the mean free path of the gas under the pressure of the introduced gas, whereby the substrate temperature during the processing can be effectively controlled in an etching process or the like at the time of manufacturing a semiconductor device. . An apparatus based on such a principle is basically a parallel plate type dry etching apparatus comprising a processing chamber 12, a lower electrode 17 having a polished convex surface, and an upper electrode 16. In this embodiment, the lower electrode 17 serves as a support. The processing chamber 12 is connected to a vacuum exhaust system (not shown) through an exhaust port 13. A reaction gas is introduced into the processing chamber 12 through a gas inlet 24. Further, the processing chamber 12 is provided with an inlet / outlet 14 for taking the substrate 20 in and out of an appropriate position. A high-frequency power supply 25 is connected between the upper electrode 16 and the lower electrode 17. The lower electrode 17 is provided with a flow path 48 through which the liquid heat medium flows, a pump 42, and a temperature control device 43 for the liquid heat medium. Further, the gas reservoir 26 for the heat transfer gas is supplied through the orifice 21 and the valve 15.
Is provided. A gas cylinder 44 is connected to the gas sump 26 via a flow control valve 45, and a gas control valve 4.
6, a rotary pump 47 is connected. The substrate holding means 23 is made of an insulating material such as ceramics, and is provided with a ball screw 4 via a spring 39.
0 and the motor 41. An O-ring 18 is provided between the substrate 19 and the lower electrode 17, and the O-ring 18 is a space 2 formed by the substrate 19 and the lower electrode.
0 is sealed from the processing chamber 12. In the above configuration, the lower electrode 17 is maintained at a constant temperature by circulating a liquid heat medium maintained at an appropriate constant temperature. As a liquid heat carrier, 20
Although water kept at ° C. is used, a fluid other than water whose temperature is controlled may be used according to the purpose. Also, the lower electrode 17
May be controlled by using electric resistance. The substrate 19 comprises a motor 41 and a ball screw 40
Then, the substrate is pressed against the lower electrode 17 by the substrate holding means 23 which moves up and down. At this time, the spring 39 is
, With a constant load, i.e., a mechanism for generating mechanical contact. The gas sump 26 is provided with a flow control valve 4.
5, 46, a gas cylinder 44 and a rotary pump 47 always keep a constant pressure and are filled with a heat transfer gas. The space 20 contains a gas reservoir 26 and an orifice 2
A gas for heat transfer is introduced via 1. That is, the gas introduction means includes the gas reservoir 26 and the orifice 21 serving as a gas introduction port. Next, how the temperature of the substrate is controlled during the processing in the above-mentioned apparatus is described by using helium as a heat transfer gas, a substrate having a diameter of 100 mm and a thickness of 0.45 mm.
The description will be made by taking the case of a silicon substrate of mm as an example. After the substrate 19 is placed, helium gas is introduced from a gas reservoir 26 at a pressure of about 700 Pa, which is one digit larger than that of the conventional example. When a gas having a pressure of 700 Pa is introduced, the center of the substrate 19 bulges at a height of about 800 μm. Further, the change amount w of the point located at a distance of r in the radial direction from the center of the substrate follows the following equation. ## EQU1 ## Here, E and v are the Young's modulus and Poisson's ratio of silicon, h and a are the thickness and radius of the substrate 19, respectively, and p is the gas pressure. Therefore, the convex surface of the lower electrode 17 is processed in advance into a curved surface having a shape according to the above equation or a curved surface which is larger than that. At this time, since the substrate 19 is pressed by the substrate support 23, it is deformed along the convex surface and has a stress. At this time, since the force applied to the substrate 19 by the gas pressure is equal to or smaller than the stress of the substrate 19, the substrate 19 does not generate a strain higher than the strain already existing due to the gas pressure. It remains in mechanical contact along the electrode 17. The surface of the lower electrode 17 is polished to a surface roughness of 6-S or less. Therefore, the distance between the two surfaces is kept sufficiently smaller than the average free path of helium at 700 Pa of 30 μm over the entire surface. Here, considering that the thermal contact between the solids can be neglected, the thermal contact is uniform over the entire surface. Therefore, sufficient thermal contact is realized, and the unit heat flow can be sufficiently increased. In the above-mentioned apparatus, an orifice 21 is provided as an introduction means for introducing a gas for heat transfer into the space 20. The diameter of the orifice 21 is about 40 μm so that the conductance with respect to helium is about 1 × 10 to ⁶ m ³ / sec. When the substrate 17 is not placed, the amount of gas flowing out of the gas reservoir 26 through the orifice into the processing chamber 12 having a pressure difference of 700 Pa is about 7 × 10 to ⁴ Pa · m ³ / sec.
This is sufficiently smaller than the reaction gas introduction amount 8 × 10 to ² Pa · m ³ / sec introduced from the reaction gas introduction port 24.
Therefore, even if the sealing between the space 20 and the processing chamber 12 is leaked, it does not adversely affect the processing.
The reliability of the temperature control mechanism according to the present embodiment is improved. Further, by providing this orifice, it is possible to eliminate the sealing by the O-ring 18, and at the same time, the valve 15 becomes unnecessary even when carrying in and carrying out the substrate 19 without breaking the vacuum of the processing chamber 12. Become. Here, after the substrate 19 is placed, the space 2
The time required for 0 to reach the same pressure as the gas reservoir 26 must be sufficiently short. When the volume of the space 20 is V, the conductance of the orifice is C, and the pressure in the gas reservoir 26 is Po, the pressure p of the space 20 follows the following equation. (6) p = Po (1−exp (−Ct / V)) Here, since the space 20 is a cylinder having a thickness of at most 100 μm, V = 7.8 × 10 to ⁷ m ³ Therefore, the time constant of the response of p is about 1 sec, which is a sufficiently fast response. In the above-described device configuration, 200 W to 50 W
FIG. 2 shows a temperature rising curve of the substrate 19 which is heated by the amount of heat received from the plasma when the high-frequency power of 0 W is applied.
Here, the time constant of the response speed is about 3 seconds, which indicates a sufficiently good control characteristic. Further, the temperature difference from the lower electrode 17 is also suppressed to 8 ° C. and 20 ° C., respectively. The resist has a heat resistant temperature of about 120 ° C.
Therefore, in this device, the additional high-frequency power is 2.5 K
That is, it can be increased to W. An embodiment of the present invention will be described with reference to FIG. In this embodiment, the substrate 1 is formed by using electrostatic attraction disclosed in Japanese Patent Publication No. 57-47747.
The liquid in the liquid / solid sump 27 or the vapor of the solid 37 is used for the point where the support 9 is performed and for the heat transfer gas. The apparatus utilizing the attractive force of static electricity is composed of a plurality of (two in FIG. 3) electrodes 3 insulated from each other.
By applying DC voltages having different polarities from the DC power supply 38 between the substrates 3 and 36, a closed circuit is formed between the substrate 19 and the two electrodes 33 and 36, and the substrate 19 is electrostatically formed without forming plasma. Can be adsorbed. Therefore, the substrate 19 can be electrostatically attracted even in the baking step of the substrate 19 without using plasma. Due to the attraction force due to the static electricity, the substrate 19 has about 10 gc
It is sucked by a force of m ~ ² , and mechanical contact occurs with the insulating material 30 over the entire surface. At this time, the O-ring 18 for sealing the space 20 formed between the substrate 19 and the insulating material 30 on the lower electrode 29 and the processing chamber 12 is provided. An orifice 21 is provided as a means for introducing gas into the orifice. In the present embodiment, the insulating material 30 serves as a support. Here, a liquid or a solid is selected so that the vapor pressure of the gas or the solid that generates the heat transfer gas is approximately 700 Pa when the vapor pressure of the gas or the solid is equal to that of the lower electrode 29 whose temperature is controlled. In this embodiment, since 1,1,2,2-tetrachloroethane is used as the heat transfer gas, the pressure is about 700 Pa at room temperature. Here, the liquid / solid used is not limited to 1,1,2,2-tetrachloroethane, and may be a liquid / solid having another vapor pressure. Since the mean free path at this time is 3 μm, the surface of the insulator 30 must be polished to 0.8S or less. Also, by using a soft organic compound for the insulating material 30 and flexibly deforming it along the shape of the lower surface of the substrate 19, the distance between the two surfaces can be made smaller than the mean free path. At this time, a vaporized gas is interposed between the two surfaces that are in mechanical contact with each other, and the distance between the two surfaces is sufficiently smaller than 3 μm, which is the mean free path of the gas at this time.
As a result, the thermal contact between the two surfaces is sufficiently large, and the unit heat flow is also large. In addition, the inside of the space 20 is 700
In order to make Pa, 1, 1, 2, 2-
Conductance to tetrachlorethane is 1 × 10
The diameter is set to 90 μm so as to be ~ ⁶ m ³ / sec. FIG. 4 shows a temperature rise curve of the substrate 19 in the above apparatus. This is an example of a case where dry etching is performed by applying a high-frequency power of 300 W. The time constant is 5 seconds, which is a sufficient value. Further, in this device, there is no need to control the gas flow and gas pressure of the heat transfer gas, and there is an advantage that the structure is simplified. A similar effect can be expected by using a wafer temperature control device disclosed in Japanese Patent Application Laid-Open No. 56-131930 as a device for reducing the distance between the substrate 19 and the support. The use of the support or the surface of the support with a soft organic compound has a great effect in reducing the distance between the two surfaces. Although the above two examples are examples in which the present invention is applied to a dry etching apparatus, the same effect can be expected even when applied to a film forming apparatus such as sputtering or vapor deposition or a substrate baking apparatus. It can be easily analogized that the present invention can be applied to other electrode means and vacuum devices that require temperature control of the substrate. According to the above embodiment, after the gas pressure between the substrate and the support is sufficiently increased, the distance between the two surfaces is made smaller than the mean free path of the gas at that gas pressure. The heat flow per unit time, unit area, and unit temperature difference between two surfaces can be reduced from the conventional 50 W · K to ¹ · m to ² to 250 W
・ It can be improved to K ~ ¹・ m ~ ² . As a result, the temperature difference between the substrate and the support during processing and the time constant for controlling the substrate temperature can be reduced to about one fifth of the conventional value. It goes without saying that the scope of the present invention is not limited to the above embodiments. According to the present invention, it is possible to effectively control the temperature of the substrate during processing such as etching, film formation, and baking of a semiconductor device, and to perform good processing. it can.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a longitudinal sectional view of a substrate processing apparatus according to the present invention. FIG. 2 is a characteristic diagram showing a temperature rise curve of a substrate in the substrate processing apparatus shown in FIG. FIG. 4 is a vertical sectional view showing another embodiment of the substrate processing apparatus. FIG. 4 is a characteristic diagram showing a temperature rising curve of the substrate in the substrate processing apparatus shown in FIG. 3. FIG. FIG. 6 is a longitudinal sectional view of a conventional substrate temperature control device. [Description of References] 1 ... Processing chamber, 3 ... Substrate, 4 ... Clip, 5 ... Support base, 6
... temperature control device, 7 ... gas inlet, 8 ... flow, 9 ... spacer, 10 ... space, 12 ... processing chamber, 17 ... support base (lower electrode), 18 ... O-ring, 19 ... substrate, 20 ... space, 2
DESCRIPTION OF SYMBOLS 1 ... Gas inlet (orifice) 23 ... Holding means, 26 ...
No gas, 27 ... No liquid solid.

────────────────────────────────────────────────── ─── Continued on the front page (51) Int.Cl. ⁶ Identification symbol FI H01L 21/68 H01L 21/68 R (72) Inventor Susumu Aiuchi Hitachi Ltd. 292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa (56) References JP-A-58-213434 (JP, A) JP-A-58-32410 (JP, A) JP-A-58-132937 (JP, A) J. Egerton et al., Solid State Technology, 25 [8] p. 84-87 (1982-8)

Claims (1)

(57) [Claims] A processing chamber provided with an exhaust means for evacuating the inside to a vacuum,
A substrate electrode means which is provided inside the processing chamber and has an upper surface on which a substrate to be processed is placed, covered with an insulator over substantially the entire surface;
Voltage applying means for applying a voltage to the substrate electrode means, a heat transfer gas supply means for supplying a heat transfer gas between the insulating material of the substrate and the substrate electrode means placed on the substrate electrode means, Gas supply means for supplying a gas into the processing chamber, counter electrode means disposed inside the processing chamber so as to face the substrate electrode means, and high-frequency power application for applying high-frequency power to the counter electrode means Means for supplying high-frequency power to the counter electrode by the high-frequency power applying means in a state in which gas is supplied from the gas supply means to the inside of the processing chamber evacuated to vacuum by the exhaust means. When processing a substrate mounted on the substrate electrode means with plasma generated between the means and the substrate electrode means, the heat transfer gas supply means supplies the substrate to be processed.
Heat transfer between the plate and the insulator of the substrate electrode means
Surface was formed with surface roughness less than mean free path
Wherein the voltage applied by said voltage applying means to the insulating material and the insulating material of the substrate electrode means the target substrate by the heat transfer gas supply means together with said adsorbed treated electrostatically over the substrate to the almost entire surface A processing apparatus, wherein the heat transfer gas is supplied to cool the substrate to be processed. 2. 2. The processing apparatus according to claim 1, wherein a pressure of the heat transfer gas supplied between the substrate to be processed and the insulator of the substrate electrode by the heat transfer gas supply unit is greater than 100 Pa. 3. . 3. The voltage applying means for applying a voltage to the substrate electrode means includes a DC power supply, and the DC power supply applies a DC voltage to an electrode portion provided inside the substrate electrode means. The processing device according to the above.