KR20030001940A - Electrostatic chuck for a plasma process apparatus - Google Patents

Abstract

PURPOSE: An electrostatic chuck for plasma processing apparatus is provided to remove various problems due to a refrigerant by using a thermoelectric semiconductor device instead of the refrigerant in a process for cooling a wafer. CONSTITUTION: An etching gas distribution plate(102) and an electrostatic chuck(10) face to each other. A plasma etching chamber(101) is connected with a grounding portion(105). A gas supply unit(104) supplies etching gases such as O2 and N2 and process gases such as Ar and He into the plasma etching chamber(101) through a gas supply tube(103). The etching gas distribution plate(102) distributes uniformly the etching gases and the process gases. A vacuum pump(108) absorbs air from the inside of the plasma etching chamber(101) in order to reduce a pressure of the inside of the plasma etching chamber(101). An electrostatic chuck(10) is used for supporting a wafer. The electrostatic chuck(10) is formed with a thermal absorbing plate(11), a thermal emitting plate(12), thermoelectric semiconductor devices(15), and electrode plates(16,17).

Description

Electrostatic chuck for a plasma process apparatus

The present invention relates to an electrostatic chuck used in a plasma processing apparatus, such as a plasma etching apparatus, and more particularly, a series of wafer cooling methods to be processed can be improved from a conventional refrigerant using method to a thermoelectric semiconductor using method. The present invention relates to an electrostatic chuck for a plasma processing apparatus which can collectively solve the conventional problems caused by the use of a refrigerant by completely excluding the refrigerant from a series of wafer cooling processes.

With the recent rapid development of technology using plasma, plasma processing apparatuses, such as plasma etching apparatuses, are also rapidly developing.

For example, US Pat. No. 5958139, "Plasma etch system," US Pat. No. 5,976,310, "Plasma etch system," US Pat. And the like, an example of a plasma etching apparatus according to the prior art is shown in more detail.

In general, an electrostatic chuck (ESC) is disposed in the above-described conventional plasma etching apparatus, which supports a wafer and assists in the smooth progress of the process, wherein the electrostatic chuck is different from other structures of the plasma etching apparatus. Since a direct contact relationship is formed with the wafer to be processed, if an abnormality occurs in the function of the electrostatic chuck, it immediately leads to a defect of the wafer. For this reason, in the conventional production line, a lot of effort is especially put into maintaining and maintaining the function of an electrostatic chuck normally.

For example, Korean Patent Laid-Open Publication No. 1992-3819, "Petrostatic Chuck and Plasma Device with Electrostatic Chuck", Korean Patent Laid-Open Publication No. 2000-32024, "Electrostatic Chuck Insulation Ring of Dry Etching Apparatus", Korean Utility Model Publication No. 1999-39626, "Electrostatic Chuck Structure of Wafer Dry Etching Equipment," etc., shows an example of the electrostatic chuck according to the related art in more detail.

In general, since the plasma processing process is generally performed in a high temperature environment, if no action is taken on the production line, the wafer to be placed on the electrostatic chuck is inevitably exposed to a high temperature environment. In the end, problems such as "a phenomenon in which the pre-formed film is burned" and "a phenomenon in which the profile of the contact hole is deformed" will be inevitably generated. You have no choice but to maintain substandard quality.

In the conventional production line, such a problem is considered in advance, for example, in Korean Utility Model Publication No. 2000-19054, "Helium flow structure of an electrostatic chuck for semiconductor etching," for example, in an electrostatic chuck in direct contact with a wafer. A method of flowing a coolant, such as helium, through which the thermal damage of the wafer to be processed can be blocked in advance, is devised.

However, in the production line, when adopting such a conventional method of using the refrigerant, the production line has to form a complicated flow path through which the refrigerant can flow inside the electrostatic chuck, which makes the manufacturing of the electrostatic chuck difficult. There is no choice but to accept.

In addition, under the conventional refrigerant utilization method, since the refrigerant flowing into the electrostatic chuck flows collectively along the entire surface of the electrostatic chuck along the preformed flow path, even if only a portion of the wafer to be processed needs to be cooled, the conventional Refrigerant use does not provide a solution.

In addition, since the refrigerant initially flowing into the inlet and the surface of the electrostatic chuck and the refrigerant flowing out of the outlet exhibit a marked temperature difference, the electrostatic chuck adopting the conventional refrigerant use method is adjacent to the inlet and the outlet. The cooling temperature of the site is inevitably changed, and as a result, the wafer to be processed cannot be provided with a uniform cooling effect over its entire surface.

Moreover, since the temperature of the refrigerant changes very variably according to the change of the surrounding environment, it is practically impossible to precisely control the temperature of the refrigerant. Consequently, in the conventional production line, the cooling temperature of the wafer to be processed is precisely adjusted. There is no choice but to take control of the problem.

On the basis of these problems, when an unexpected abnormality occurs in the structure formed on the wafer to be processed, the semiconductor device manufactured based on this wafer has no choice but to maintain a quality below a certain level.

Accordingly, an object of the present invention is to improve the series of wafer cooling methods to be processed from the conventional refrigerant using method to the thermoelectric semiconductor using method, thereby completely excluding the refrigerant from the series of wafer cooling processes, thereby resulting in the use of the refrigerant. Problems such as "problem of forming a coolant flow path", "problem of partially cooling the wafer to be processed", and "cooling temperature of the wafer to be processed can be kept uniform over the entire surface of the wafer. Problem "," a problem that cannot precisely control the cooling temperature of the wafer to be processed "and the like.

Another object of the present invention is to solve the problems caused by the use of the refrigerant, thereby minimizing the problems that can occur in any wafer wafer during the series of plasma process, thereby the quality of the semiconductor device based on the wafer To improve the level above a certain level.

Still other objects of the present invention will become more apparent from the following detailed description and the accompanying drawings.

1 is a perspective view showing an electrostatic chuck for a plasma processing apparatus according to the present invention.

Figure 2 is an enlarged perspective view showing the arrangement of the thermoelectric semiconductor elements of the present invention.

3 is a cross-sectional view of FIG.

In order to achieve the above object, in the present invention, a heat absorbing plate disposed inside the plasma processing chamber, which supports a wafer to be processed and absorbs the heat retained by the wafer to be processed, and is in series with the bottom side of the heat absorbing plate. Thermoelectric semiconductor devices, which are lined up and arranged in a row, are moved and supported by the heat conduction elements, and move the heat absorbed by the heat absorbing plate to another place. The heat dissipation plate for dissipating the transferred heat to the outside, and the electrode plate interposed between the heat dissipation plate, the heat absorbing plate, and the thermoconductor elements mentioned above, and transfers external electrical energy to the preceding heat conductor elements. An electrostatic chuck for a plasma processing device comprising a combination of the above is disclosed.

Hereinafter, with reference to the accompanying drawings, the electrostatic chuck for plasma processing apparatus according to the present invention will be described in more detail.

As shown in Fig. 1, the plasma processing apparatus, for example, the plasma etching apparatus 100, to which the present invention is employed, is largely divided into the plasma etching chamber 101, the etching gas distribution plate 102, the electrostatic chuck 10, and the gas. It consists of a combination of supply unit 104, vacuum pump 108, and the like. In this case, the etching gas distribution plate 102 and the electrostatic chuck 10 of the previous form a structure, for example facing each other, the plasma etching chamber 101 forms a structure grounded by the ground portion 105.

In this case, the gas supply unit 104 serves to supply, for example, etching gas such as O ₂ and N ₂ and process gas such as Ar and He to the inside of the plasma etching chamber 101 through the gas supply pipe 103. The etching gas distribution plate 102 uniformly distributes the etching gas, the process gas, and the like output from the gas supply unit 104, and evenly distributes the etching gas and the process gas in the plasma etching chamber 101, and vacuum The pump 108 sucks air in the plasma etching chamber 101 to reduce the pressure in the plasma etching chamber 101.

Here, as shown in the figure, the electrostatic chuck 10 constituting the gist of the present invention supports the wafer 1 to be processed, and assists the smooth progress of the process, for example, the etching process. Of course, since the electrostatic chuck 10 forms a direct contact relationship with the wafer to be processed, unlike other structures in the plasma etching chamber, if the electrostatic chuck 10 of the present invention is abnormal in function. If this occurs, this immediately leads to the failure of the wafer 1 to be processed.

At this time, as shown in the figure, the electrostatic chuck 10 according to the present invention is large, the heat absorbing plate 11, the heat dissipation plate 12, the thermoelectric semiconductor elements 15 and the electrode plates (16, 17) ) Is a combination.

Here, the heat absorbing plate 11 directly supports the wafer 1 to be processed, and serves to absorb heat retained by the wafer 1 to be processed. In this case, the heat absorbing plate 1 is made of a ceramic material having a high thermal conductivity while maintaining low electrical conductivity, for example, an AlN material.

At this time, the former thermoconductor elements 15 form a structure arranged in line on the bottom surface of the above-described heat absorbing plate 11, in this state, the heat absorbing plate 11 is a wafer to be processed When (1) absorbs the heat retained, it serves to move the heat to another place. In this case, the thermoconductor elements 15 of the present invention have a structure in which, for example, the P-type thermoconductor elements 13 and the N-type thermoconductor elements 14 are alternately arranged and arranged, and thus, a series of "PN elements". Large ".

In general, when the thermoelectric elements 15 are applied with an appropriate level of electrical energy, electrons or holes are rapidly moved by a so-called "Peltier effect", so that the thermoelectric elements 15 Known as special semiconductor devices that promote the cooling of the object by transporting heat, the present invention applies the properties of these thermoconductor elements 15, in series to the underside of the heat absorbing plate 11. By arranging and selectively supplying a series of electrical energy to the corresponding thermoconductor elements 15, the heat absorbed by the heat absorbing plate 11 is changed to another place by the Peltier effect of the thermoconductor elements 15. For example, it is guided so that it can be quickly transmitted and discharged to the heat dissipation plate 12 described later.

At this time, in the present invention, a material having a high thermal conductivity performance index is selected as the above-described thermal semiconductor elements 15. Typically, this thermal conductivity figure is expressed as <Z = α ² / ρκ> (where α is the intrinsic Seebeck coefficient, ρ is the specific resistivity of the material, and κ is the thermal conductivity of the material). In the present invention, with reference to this, for example, Bi ₂ Te ₃ , Bi ₂ Se ₃ , Sb ₂ Te ₃ and the like, by selecting a material having a low thermal conductivity and high resistivity as the thermoelectric semiconductor elements 15, Make the "heat transfer induction effect" more smoothly.

On the other hand, as shown in the figure, the above-mentioned thermoconductor elements 15 form a structure supported by the heat dissipation plate 12. In this state, the heat dissipation plate 12 plays a role of rapidly dissipating the retaining heat of the wafer to be processed 1 transferred to the outside via the heat absorbing plate 11 and the thermoelectric elements 15. The heat absorbed by the heat absorbing plate 11 is induced so as not to accumulate in the electrostatic chuck 10. The heat dissipation plate 12 is made of a metal having excellent thermal conductivity, for example, copper.

At this time, a series of upper and lower electrode plates 16 and 17 are interposed between the heat dissipation plate 11 and the thermoconductor elements 15 and between the heat absorber plate 12 and the thermoconductor elements 15. The upper and lower electrode plates 16 and 17 receive electric energy of a predetermined size from, for example, the power supply unit 106 grounded by the grounding unit 108, and then transfer the electric energy to thermoelectric devices. It delivers to the semiconductor devices 15.

Here, as shown in FIG. 2, the aforementioned thermoelectric semiconductor elements 15 of the present invention, that is, the P-type thermoelectric elements 13 and the N-type semiconductor elements 14 are densely arranged in a line. In this case, if some of the thermoconductor elements 15 densely arranged in a predetermined area in the production line are removed as necessary, the previous heat absorbing plate 11 is affected. The heat absorption rate of the portion corresponding to the removal region may be reduced to a certain extent, and consequently, in the production line, by appropriately adjusting the density of the thermoelectric elements 15, the "heat absorption function" of the heat absorption plate If necessary, it is possible to easily obtain a locally adjustable effect.

Here, as shown in FIG. 3, the upper electrode plate 16 and the heat absorbing plate 11 and the lower electrode plate 17 and the heat dissipating plate 12 are formed of, for example, an insulating material. Lower heat loss barriers 19 and 18 are further interposed. The upper and lower heat loss blocking plates 19 and 18 store the heat moving from the heat absorbing plate 11 toward the heat dissipating plate 12 from the external environment, so that the heat is, for example, the plasma etching chamber 101. It serves to prevent the phenomenon of backflowing back to the internal space of the. In addition, the above-described heat loss blocking plates 19 and 18 induce and form a series of electrostatic fields in accordance with the electric energy supply state of the power supply unit 106, so that the above-described process target wafer 1 has a different problem. It serves as a guide so that it can be seated on the heat absorbing plate without. The upper and lower heat loss blocking plates 19 and 18 are made of a material such as alumina, polyimide, etc. having excellent insulation.

Hereinafter, the operation of the electrostatic chuck 10 for plasma processing apparatus according to the present invention having the above-described configuration will be described in detail.

First, when a series of plasma processing processes, for example, a plasma etching process is started, in the present invention, first, the vacuum pump 108 is quickly operated to reduce the pressure in the plasma etching chamber 101.

Subsequently, in the present invention, the gas supply unit 104 is controlled so that the etching gas such as O ₂ , N _2, and process gas such as Ar, He, or the like are supplied into the plasma processing chamber 101. Feed through. The etching gas, the process gas, and the like thus supplied are uniformly distributed by the etching gas distribution plate 102 and are evenly distributed in the plasma etching chamber 101.

When the etching gas, the process gas, and the like are evenly distributed in the plasma etching chamber 101 through the foregoing process, in the present invention, at the point of similarity, between the upper and lower electrodes (not shown) of the plasma etching chamber 101. For example, while applying a high frequency of about 13MHz to 15MHz, by rotating the permanent magnet by a motor, a magnetic field of a predetermined size can be formed between the upper and lower electrodes.

Through the above process, if a magnetic field of a predetermined size is formed between the upper and lower electrodes, the electrons existing between each electrode, for example, by performing a cyclotron (Cyclotron) movement, collides with the etching gas molecules As a result, the etching gas molecules are ionized and ionized by the impact, thereby generating a certain amount of plasma.

The plasma generated as described above is adsorbed on the surface of the wafer 1 to be processed seated on the electrostatic chuck 10 of the present invention and causes a series of chemical reactions, whereby the wafer 1 to be processed is a predetermined series of etchings. Make the process easy to follow.

When the plasma etching process is performed, in the present invention, the power supply unit 106 is controlled to apply an electric energy of a predetermined size to the electrode plate disposed on the electrostatic chuck 10, for example, the lower electrode plate 17. As a result, this electrical energy is transferred to the thermoconductor elements 15 via the upper and lower electrode plates 16 and 17.

Through the above process, when a series of electrical energy is transferred to the thermoconductor elements 15 between the upper and lower electrode plates 16 and 17, the holes in the thermoconductor elements 15 immediately become heat. While moving toward the discharge plate 12, the above-described Peltier effect carries the heat of retention of the wafer 1 to be processed in contact with the heat absorbing plate 11, thereby allowing the wafers 1 to be processed. The retaining heat is rapidly released toward the heat dissipation plate 12, and as a result, the wafer to be processed is rapidly cooled without a conventional refrigerant.

At this time, the upper and lower heat loss blocking plates 19 and 18 store the heat moving from the heat absorbing plate 11 toward the heat dissipating plate 12 from the external environment, so that the heat is, for example, the plasma etching chamber 101. To prevent backflow into the internal space.

Here, as mentioned above, since the thermoelectric semiconductor elements 15 operate based on externally supplied electrical energy, if the electrical energy supplied to the lower electrode plate 17 in the production line is precisely In the case of control, the production line can precisely control the operating states of the thermoelectric semiconductor elements 15 based on this, and as a result, the cooling temperature of the wafer 1 to be processed can be easily controlled as necessary. Of course, the cooling temperature of the wafer 1 can be maintained uniformly over the entire surface of the wafer.

Of course, as mentioned above, when properly adjusting the density of the thermoconductor elements 15 in the production line, since the "heat absorption function" of the heat absorbing plate can also be locally adjusted, if necessary, production In the line, the wafer to be processed may be partially cooled.

Subsequently, the process target wafer 1 which has completed the plasma etching step is further processed through a series of subsequent steps, whereby it is manufactured and completed with any semiconductor device having excellent performance.

As described in detail above, the present invention improves the series of wafer cooling methods to be processed from the conventional refrigerant using method to the thermoelectric semiconductor using method, thereby completely excluding the refrigerant from the series of wafer cooling processes.

When the present invention is achieved, the production line can precisely control the electrical energy supplied to the electrode plate, so that it is possible to precisely control the operating state of the thermoelectric semiconductor elements, the cooling temperature of the wafer to be processed, if necessary Can be precisely controlled, and the cooling temperature of the wafer can be maintained uniformly over the entire surface of the wafer.

In addition, when the present invention is achieved, since the density of the thermoelectric elements can be properly adjusted in the production line to locally control the "heat absorption function" of the heat absorbing plate, the wafer to be processed is partially formed as necessary. It can also cool.

As a result, when the present invention is achieved, since the problems caused by the use of the refrigerant are collectively solved, the production line can obtain the effect of minimizing the problems that may occur in any target wafer during the series of plasma processes. As a result, the effect of improving the quality of the semiconductor device based on the wafer above a certain level can be easily obtained.

This invention can be variously modified depending on the situation.

For example, when the potential of the electrical energy supplied to the preceding electrode plate is applied in the reverse direction, the functions of the heat absorbing plate and the heat dissipating plate may be reversed, and in this case, the electrostatic chuck of the present invention may be used in a production line. Can be easily utilized for wafer heating, not for wafer cooling.

While specific embodiments of the invention have been described and illustrated above, it will be apparent that the invention may be embodied in various modifications by those skilled in the art. Such modified embodiments should not be understood individually from the technical spirit or point of view of the present invention and such modified embodiments should fall within the scope of the appended claims of the present invention.

Claims (6)

A heat absorbing plate disposed inside the plasma processing chamber and supporting an arbitrary wafer to be processed and absorbing heat held by the wafer to be processed; A plurality of thermoelectric semiconductor devices which are arranged in series on the bottom side of the heat absorbing plate, are arranged and arranged in a row, and move heat absorbed by the heat absorbing plate to another place; A heat dissipation plate supporting the thermoelectric semiconductor elements and dissipating heat transferred by the thermoelectric semiconductor elements to the outside; And an electrode plate interposed between the heat release / absorption plate and the thermoconductor elements and transferring external electrical energy to the thermoconductor elements. The electrostatic chuck of claim 1, further comprising a heat loss blocking plate formed between the electrode plate and the heat release and absorption plate to block a loss of heat that moves the heat release and absorption plate. The electrostatic chuck of claim 2, wherein the heat loss blocking plate is made of alumina or polyimide. The electrostatic chuck of claim 1, wherein the heat absorbing plate is made of AlN. The electrostatic chuck of claim 1, wherein the thermoelectric semiconductor elements comprise any one of Bi ₂ Te ₃ , Bi ₂ Se ₃ , and Sb ₂ Te ₃ . The electrostatic chuck of claim 1, wherein the heat dissipation plate is made of metal.