JPH0453135A - Processor - Google Patents

Abstract

PURPOSE:To ensure good transfer of heat to the side of a setting plate from the side of a material to be processed and always keep temperature thereof within a predetermined range by introducing a gas under the predetermined pressure into the region between the material to be processed and the setting plate and keeping a pressure to a constant value. CONSTITUTION:A semiconductor wafer 6 is placed on a setting plate 2 within a vacuum vessel 1 and it is held with a predetermined clamp load with a clamp ring 8. Next, a gas which is a heat transfer medium is introduced, from a gas introducing pipe 13, into a small gap 12 between an elastic film 5 and the semiconductor wafer 6 placed on the setting plate 2. When the pressure in the small gap 12 reaches a predetermined value, a pressure adjusting valve 22 is opened, maintaining the pressure within the small gap 12 to the predetermined value under the condition that the heat transfer medium gas is continuously supplied, at the predetermined flow rate, to the side of a pressure adjusting mechanism 14. The pressure of gas to be introduced into the small gap 12 is set so that distance between semiconductor wafer 6 and the upper surface of the setting plate 22 is almost equalized over the entire surface of semiconductor wafer 6.

Description

[Detailed description of the invention] [Purpose of the invention] (Industrial application field) The present invention relates to a processing device.

(Prior Art) Generally, in the manufacturing process of semiconductor devices, various semiconductor manufacturing equipment is used that performs processes under reduced pressure, such as processing equipment such as etching equipment, ashing equipment, ion implantation equipment, and sputtering equipment. . In each of these apparatuses, desired processing is normally performed on a semiconductor wafer, which is an object to be processed, held on a mounting table in a vacuum or under a reduced pressure atmosphere.

In the various manufacturing equipment described above, in order to prevent the semiconductor wafer from rising in temperature during the processing process, melting the element elements, changing the physical characteristics, etc. and reducing the uniformity of the processing,
Processing is performed while cooling the semiconductor wafer by, for example, providing a cooling jacket on the mounting table side.

By the way, there is generally a microscopic space between the mounting table and the back surface of the semiconductor wafer due to the roughness of the back surface of the wafer, and in processing under a reduced pressure atmosphere, this space is also in a reduced pressure state, so the above-mentioned When such a method of indirectly cooling the semiconductor wafer is adopted, there is a problem in that the presence of the reduced pressure space significantly deteriorates heat transfer, making it impossible to effectively cool the semiconductor wafer.

Therefore, it has been proposed to introduce gas to such an extent that heat transfer between the mounting table and the semiconductor wafer is not inhibited, thereby preventing a decrease in cooling efficiency.

(Problem to be Solved by the Invention) However, in conventional semiconductor manufacturing equipment, the amount of gas introduced between the mounting table and the semiconductor wafer is controlled only by adjusting the flow rate, or a certain amount of gas is sealed and various types of gas are introduced. Therefore, if the introduced gas leaks during the processing, the heat transfer efficiency decreases, resulting in an abnormal temperature rise of the semiconductor wafer.

Furthermore, depending on the amount of gas introduced between the mounting table and the semiconductor wafer, the amount of heat transfer differs between the center and the peripheral portion of the semiconductor wafer, resulting in a problem that the temperature distribution of the semiconductor wafer tends to be uneven.

The present invention has been made to address the problems of the prior art, and is a method for maintaining good heat transfer efficiency between the workpiece and the mounting table when processing is performed in a reduced pressure atmosphere or in a vacuum. Another object of the present invention is to provide a processing apparatus that can maintain a uniform temperature distribution of the object to be processed.

[Structure of the Invention] (Means for Solving the Problems) That is, the present invention provides a method for providing a workpiece held on a mounting table with a gas introduced between the workpiece and the mounting table. A processing device that performs predetermined processing under reduced pressure while controlling the temperature of the processed material, which has a pressure adjustment mechanism that controls the amount of gas introduced by pressure and keeps the pressure of the introduced gas constant. It is characterized by this.

(Function) In the processing apparatus of the present invention, gas is introduced at a predetermined pressure between the object to be processed and the mounting table, and the pressure is kept constant, so the gas is used as a heat transfer medium. As a result, heat can be transferred favorably from the object to be processed to the mounting table, and this state of heat transfer can be maintained stably during the processing process. Therefore, the temperature of the object to be processed can always be maintained within a predetermined temperature range.

Further, by adjusting the pressure so that the distance between the object to be processed and the mounting table is kept substantially constant, the state of heat transfer throughout the object to be processed can be made uniform. This is because the amount of heat transfer depends on the distance between the object to be processed and the placement. Therefore, it is possible to maintain a uniform temperature distribution of the object to be processed.

(Example) Hereinafter, an example in which the apparatus of the present invention is applied to an etching apparatus will be described with reference to the drawings.

As shown in FIG. 1, a mounting table 2 made of, for example, aluminum with an alumite coating, which also serves as a lower electrode, and an upper electrode 3 are disposed facing each other in the vacuum container 1. A predetermined vacuum condition inside, for example, several tens of W.
An exhaust system 4 capable of exhausting up to several tens of Torr is connected.

An elastic film 5 such as a polyimide resin Kapton film (trade name) is placed on the upper surface of the mounting table 2, and an object to be processed, such as a semiconductor wafer 6, is placed on the elastic film 5. Then, on the outer circumferential side of the mounting table 2,
For example, a clamp ring 8 that can be raised and lowered by a drive mechanism 7 such as an air cylinder is disposed, and by pressing the semiconductor wafer 6 against the elastic film 5 with the clamp ring 8, the semiconductor wafer 6 is moved to a predetermined position. It is held on the mounting table 2 with a clamp load.

Further, the upper surface of the mounting table 2 is such that the clamping load applied to the peripheral edge of the semiconductor wafer 6 by the clamping ring 8 is applied to the upper surface of the mounting table 2.
It is formed into a convex shape with a curved surface that is almost the same as the deformation curved surface of the semiconductor wafer 6 when it is assumed that a uniformly distributed load is applied by fixing the periphery of the semiconductor wafer 6 .

The mounting table 2 is for holding the semiconductor wafer 6 in a cooling manner, and a cooling jacket 9 is built inside the mounting table 2 . A cooling medium introduction pipe 10 and a cooling medium discharge pipe 11 are connected to the cooling jacket 9, and the semiconductor wafer 6 is cooled by circulating a cooling medium such as cooling water inside the cooling jacket 9.

Here, as shown in FIG. 2, there is a minute space 12 between the elastic film 5 placed on the top surface of the mounting table 2 and the semiconductor wafer 6 due to the surface roughness of the back surface of the wafer.
is inevitably formed. A gas introduction pipe 13 is provided through the central portion of the mounting table 2 to introduce a gas to serve as a heat transfer medium between the mounting table 2 and the semiconductor wafer 6 into the microspace 12. This gas introduction pipe 13 is connected to a gas supply source 15 placed outside the vacuum container 1 via a pressure adjustment mechanism 14 .

A flow rate regulator 17 for adjusting the flow rate of gas introduced into the gas supply source 15 side is inserted into the main pipe 6 in the pressure adjustment mechanism 14, and further includes a main on-off valve 18 and a pressure gauge 1.
It is connected to the gas introduction pipe 13 on the mounting table 2 side via 9. Further, a sub-piping 20 is connected between the main on-off valve 18 and the pressure gauge 19 of the main pipe 16, and the sub-piping 20 is connected to a vacuum pump 23 via an on-off valve 21 and a pressure regulating valve 22. It is connected. The pressure regulating valve 22 is controlled by a controller 24 according to the pressure in the micro space 12 between the elastic film 5 and the semiconductor wafer 6 measured by a pressure gauge 19, and the main on-off valve 18 and the on-off valve 21 are controlled by a controller 24. are configured to work together.

Here, as the heat transfer medium gas, for example, an inert gas such as nitrogen gas, helium, argon, etc. is used, and it is also possible to use a reaction gas for process, etc., depending on the type of gas. It is not limited.

In the pressure adjustment mechanism] 4, the pressure inside the microspace 12 is adjusted as follows.

The heat transfer medium gas whose flow rate is adjusted to a predetermined flow rate by the flow rate regulator 17 is constantly supplied through the main pipe 16. Further, the pressure within the microspace 12 is continuously measured by a pressure gauge 19. When the value of the pressure gauge 19 reaches a predetermined value, the pressure regulating valve 22 is controlled by the controller 24.
is in the open state, and excess heat transfer medium gas is pumped to the vacuum pump 2.
The pressure inside the micro space 12 is maintained at the set pressure.

On the other hand, if the pressure in the micro space 12 becomes lower than the set value due to leakage of heat transfer medium gas from inside the micro space 12, the pressure regulating valve 22 is closed, and the heat transfer medium gas leaks from inside the micro space 12. Gas is supplied through the gas introduction pipe 13 to a predetermined pressure.

Further, the above-mentioned upper electrode 3 is connected to a reaction gas supply pipe 25, and the lower surface of the upper electrode 3 is provided with a minute hole (not shown), and the reaction gas is passed through this minute hole. , for example, argon gas, etc., is allowed to flow 8 into the vacuum vessel 1 .

A high frequency power source (not shown) connected to the upper electrode 3 generates plasma between the upper electrode 3 and the mounting table 2, which is the lower electrode. In addition,
The mounting table 2 is electrically grounded in this embodiment. Of course, electric power may be added.

The etching operation in the etching apparatus with the above configuration is as follows:
For example, this is done as follows.

That is, first, the semiconductor wafer 6 is placed on the mounting table 2 in the vacuum container 1 which has been evacuated to a predetermined vacuum state, and is held by the clamping ring 8 with a predetermined clamping load. next,
A gas serving as a heat transfer medium is introduced from the gas introduction pipe 13 into the microspace 12 between the elastic film 5 and the semiconductor wafer 6 placed on the mounting table 2 according to the following procedure.

First, from the gas supply source 15, for example, 0.7 kg/cm2 to
The heat transfer medium gas supplied at a pressure of about 1.0 kg/co+2 is adjusted to a predetermined flow rate, for example 0, by the flow regulator 17.
Adjust to about 208 CCM. This is the microspace 12
This is to prevent a large amount of gas from being introduced into the semiconductor wafer 6 at once and causing an abnormal clamping state of the semiconductor wafer 6.

The heat transfer medium gas adjusted to a predetermined flow rate is introduced into the microspace 12 from the gas introduction pipe 13 via the main pipe 16 . Note that at the time of this gas introduction, the pressure within the microspace 12 has not reached the predetermined set pressure, so the pressure regulating valve 22 is in a closed state.

When the pressure within the microspace 12 measured by the pressure gauge 19 reaches a predetermined pressure, the pressure regulating valve 22
is in the open state and continues to supply the heat transfer medium gas to the pressure adjustment mechanism 14 side at a predetermined flow rate.
The internal pressure is maintained at a predetermined level.

Furthermore, since the peripheral edge of the semiconductor wafer 6 is pressed against the mounting table 2 via the elastic film 5 by the crumpling 8, the heat transfer medium gas is sealed in the microspace 12. When the heat transfer medium gas leaks as the process progresses and becomes lower than the set pressure, the pressure regulating valve 21 is closed and the heat transfer medium gas is supplied up to the set pressure. In this way, the pressure within the microspace 12 is constantly maintained at a predetermined pressure.

Here, the set pressure of the gas introduced into the microspace 12 is set so that the distance g between the semiconductor wafer 6 and the top surface of the mounting table 2 is approximately equal over the entire surface of the semiconductor wafer 6, as shown in FIG. Set. This is because the amount of heat transfer is determined by the distance g. In other words, if the introduction pressure of the heat transfer medium gas is set too high, only the distance g near the center of the semiconductor wafer 6 where the gas introduction pipe 13 is arranged increases, and the uniformity of the temperature distribution of the semiconductor wafer 6 decreases. It's for a reason. Specifically, the set pressure is preferably a value below the introduced gas pressure at which the heat transfer coefficient is saturated, for example, a value of about 10 Torr when the heat transfer coefficient is saturated at about 20 Torr.

Then, by applying a predetermined RF power to the upper electrode 3, plasma is formed between the upper electrode 3 and the mounting table 2 which also serves as the lower electrode, and a predetermined etching process is performed.

During the etching process, the temperature of the semiconductor wafer 6 increases due to the formed plasma and the etching operation, but the temperature between the semiconductor wafer 6 and the mounting table 2 increases through the heat transfer medium gas introduced into the microspace 12. Heat is transferred between them, and the cooling water circulated within the cooling jacket 9 cools and maintains the temperature within a predetermined range.

In this way, in the etching apparatus of the above embodiment,
A heat transfer medium gas is introduced into the micro space 12 between the elastic film 5 and the semiconductor wafer 6 placed on the mounting table 2, and a thermal connection is established with the mounting table 2 through this heat transfer medium gas. Therefore, it is possible to set a sufficiently large heating flux using the heat transfer medium gas. The amount of heat transfer medium gas introduced is controlled by pressure, and
Since the pressure is maintained constant, the heat transfer state between the mounting table 2 and the semiconductor wafer 6 can be kept good and constant during the processing process, and the semiconductor wafer 6 can be cooled efficiently.
Moreover, it becomes possible to perform the process stably.

Further, in the above embodiment, the set pressure in the microspace 12 is set to a pressure such that the distance g between the semiconductor wafer 6 and the top surface of the mounting table 2 is almost uniform over the entire semiconductor wafer 6, so that the entire surface of the semiconductor wafer 6 is In this case, the heat transfer coefficient, in other words, the cooling efficiency becomes constant, and it becomes possible to maintain a uniform temperature distribution of the semiconductor wafer 6.

Since the semiconductor wafer 6 can always be cooled stably and efficiently in this way and a uniform temperature distribution can be maintained, it becomes possible to perform stable and efficient etching processing.

In the above embodiment, an example was explained in which the processing apparatus of the present invention is applied to an etching apparatus, but the present invention is not limited to this (for example, it can be applied to an ashing apparatus, an ion implantation apparatus, a sputtering apparatus, etc.). It is effective for various semiconductor manufacturing equipment that processes under reduced pressure, and can obtain the same effect as the above-mentioned etching equipment.It is also useful not only for processing semiconductor wafers, but also for forming TPT circuits on liquid crystal substrates, etc. May be applied.

[Effects of the Invention] As described above, according to the processing apparatus of the present invention, it is possible to stably and efficiently cool the object to be processed, and therefore it is possible to stably perform the desired processing. Also,
By keeping the temperature distribution of the object to be processed uniform, the processing quality can be further improved.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the configuration of an etching apparatus according to an embodiment to which the semiconductor manufacturing apparatus of the present invention is applied, and FIG. 2 is a microscopic view of the state between the mounting table and the semiconductor wafer in the etching apparatus. FIG. 3 is a diagram schematically showing the relationship between the mounting table of the etching apparatus of the above embodiment and the semiconductor wafer. 1... Vacuum container, 2... Placement table, 3.
... Upper electrode, 5 ... Elastic film, 6
... Semiconductor wafer, 8 ... Crumbling, 9 ... Cooling jacket, 12 ...
・Minute space, 13...Gas introduction pipe, 14...
... Pressure adjustment mechanism, 15 ... Gas supply source, 1
6... Main piping, 17... Flow rate regulator,
19...Pressure gauge, 20...Sub-piping, 22...Pressure adjustment valve, 23...Vacuum pump.

Claims (1)

[Claims] A workpiece held on a mounting table is heated under reduced pressure while controlling the temperature of the workpiece through gas introduced between the workpiece and the mounting table. A processing apparatus that performs a predetermined process, comprising: a pressure adjustment mechanism that controls the amount of gas introduced by pressure and keeps the pressure of the introduced gas constant.