KR100959566B1 - Electrostatic Chuck System and Electrostatic Chuck having a improved cooling system - Google Patents

Abstract

The present invention relates to an electrostatic chuck for use in the manufacture of semiconductor devices, and more particularly, to an electrostatic chuck having an improved cooling system capable of maintaining the temperature characteristics of the electrostatic chuck uniformly.

The configuration of the present invention comprises at least two refrigerant supply holes and at least two refrigerant outlets in the flow path portion formed in the lower electrode of the electrostatic chuck, and the flow path portion is composed of the first flow passage portion and the second flow passage portion, and a boundary wall is provided therebetween. It is possible to control each of the refrigerant supply and discharge separately, it is possible to provide an electrostatic chuck that can prevent the temperature imbalance by uniformly realizing the temperature of the edge portion and the center of the electrostatic chuck.

Refrigerant supply hole, refrigerant discharge hole, interface.

Description

Electrostatic Chuck System and Electrostatic Chuck Having a Improved Cooling System

1 is a view showing a flow path portion of a lower electrode of an electrostatic chuck according to the prior art.

FIG. 2 is a cross-sectional view of a lower electrode including an upper plate and a lower plate as a cross-sectional view of the lower electrode shown in FIG. 1. FIG.

3 is a partial cross-sectional view of a typical electrostatic chuck, showing a cooling gas groove and a flow path portion, showing an electrostatic sheet mounted on the lower electrode.

4 is a view showing the lower plate and the upper plate of the lower electrode of the electrostatic chuck according to an embodiment of the present invention and the electrostatic sheet to be mounted on the lower electrode.

5A is a plan view showing a top plate of the lower electrode of the electrostatic chuck of one embodiment according to the present invention shown in FIG.

FIG. 5B is a cross-sectional view illustrating a form in which a lower plate is adhered to the lower plate of the lower electrode illustrated in FIG. 5A.

6 illustrates an electrostatic chuck system in accordance with another embodiment of the present invention.

Explanation of symbols on the main parts of the drawings

513,515: refrigerant supply hole 512,514: refrigerant discharge hole

527a, 527b: heat transfer plate 426,526: interface                 

630: controller 641: first refrigerant tank

The present invention relates to an electrostatic chuck for use in the manufacture of semiconductor devices, and more particularly, to an electrostatic chuck having an improved cooling system capable of maintaining the temperature characteristics of the electrostatic chuck uniformly.

A semiconductor device is typically obtained by implementing an electronic circuit device by a patterning process of a conductive layer and an insulating layer on the surface of a wafer using photolithography or the like, and the conductive layer and the insulating layer are patterned by etching or deposition on the wafer surface.

The etching or deposition is performed in the process chamber after the semiconductor substrate (eg, the wafer) is fixed to the electrostatic chuck electrostatically, and the etching or deposition is performed by maintaining a plasma atmosphere in the process chamber.

In the plasma process, since the electrostatic chuck is also used as a plasma generating electrode, the temperature of the electrostatic chuck increases due to plasma heating. In other words, in a dry etching process using a plasma or the like, a negative bias voltage is applied to the semiconductor substrate. As a result, ions and the like incident on the semiconductor substrate are accelerated to cause a physical etching reaction. In this case, kinetic energy such as ions incident on the semiconductor substrate is mostly converted into thermal energy to increase the temperature of the semiconductor substrate. If the temperature of the electrostatic chuck rises, it will have a thermal effect on the wafer fixed on the top surface of the electrostatic chuck.

As such, thermal variations in the wafer not only cause the distribution of critical dimensions (CD) within the wafer, but also cause variations in the critical dimensions between the wafers.

In addition, since the wafer temperature is an important process variable affecting the etching rate, the film thickness and the uniformity, the wafer temperature control in the chamber in which the process is in progress is an important factor in the semiconductor device manufacturing process.

Thus, in order to prevent temperature imbalance of such wafers, the electrostatic chuck is typically configured to have a cooling system.

In such a cooling system, in order to adjust the surface temperature of the wafer, a cooling gas such as helium is supplied to the upper surface of the electrostatic chuck on which the wafer is loaded (that is, the back of the wafer) to cool the back of the wafer.

However, because it is not enough to cool the wafer back with only cooling gas, the lower electrode of the electrostatic chuck (also called a plasma generating electrode or body) is made of a material such as aluminum, and a flow path through which the refrigerant can flow inside the aluminum. By manufacturing the part, the lower electrode of the electrostatic chuck is cooled.

However, in recent years, as the diameter of the wafer is 6 or replaced with 8 inches to 12 inches, the above-described conventional technology rapidly reduces the cooling efficiency of the wafer at the edge portion or the center portion, so that the temperature of the wafer edge portion and the temperature of the wafer center portion during the process are reduced. A temperature difference occurs between them.                         

Hereinafter, a structure of a conventional electrostatic chuck will be described in detail with reference to FIGS. 1 and 2. FIG. 1 is a plan view showing a flow path portion 104 of a conventional wafer fixing electrostatic chuck lower electrode, and FIG. As a cross-sectional view of the flow path part, a state in which the lower plate 211 is attached to the lower plate 221 of the lower electrode is illustrated.

The flow path part 104 formed in the lower electrode 200 of the conventional electrostatic chuck is configured to have only one refrigerant supply hole 102 and one refrigerant outlet 103.

While the refrigerant supplied to the one refrigerant supply hole 102 flows along the flow path portion 104 to lower the temperature of the lower electrode and is discharged through the one refrigerant discharge port 103, the refrigerant flows through the relatively long flow path portion 104. The temperature of the coolant rises, causing a temperature imbalance at the center and the edge. In particular, the 12-inch large-diameter wafer etch deepens the temperature imbalance.

3, reference numeral 301 denotes a wafer, 304 denotes a flow path portion, 305 denotes a cooling gas groove, 306 denotes an electrode for electrostatic absorption, 307 denotes an electrostatic sheet, and 308 denotes a lower electrode (plasma generating electrode). 311 denotes a lower plate of the lower electrode, and 321 denotes an upper plate of the lower electrode.

3 is a partial cross-sectional view of the electrostatic chuck showing the state in which the wafer 301 is fixed on the electrostatic sheet 307. The refrigerant is first flowed into the flow path 304 of the lower electrode 308 to further cool it. The figure shows cooling the wafer by flowing a cooling gas such as helium through the cooling gas groove 305.

As shown in FIG. 3, the electrostatic chuck typically controls the temperature of the wafer using the cooling gas groove 305 and the flow path 304. However, as mentioned above, since the flow path portion of the conventional electrostatic chuck shown in FIG. 1 is composed of only one refrigerant supply hole 102 and only one refrigerant discharge hole 103, uniform temperature control of the wafer is impossible. It can be seen that.

Here, simply defined with respect to the term used herein, the electrostatic chuck refers to a wafer holding device consisting of an electrostatic sheet and a lower electrode, the electrostatic sheet refers to a sheet consisting of a structure of a dielectric-electrode-dielectric bonded to the lower electrode. Or, it refers to an anodizing film formed on the lower electrode, the lower electrode refers to the electrode for plasma generation of aluminum material attached to the lower surface of the electrostatic sheet. It should also be noted that the lower electrode is commonly referred to as the body in the art.

Accordingly, an object of the present invention is to solve or alleviate the above-described problems of the prior art, and comprises two or more refrigerant supply holes and two refrigerant outlets, respectively, and divides the flow path into a first flow path and a second flow path. It is to provide an electrostatic chuck that can maintain a uniform temperature between the edge portion and the center of the electrostatic chuck by providing a boundary wall therebetween.

Another object of the present invention is to provide an electrostatic chuck system capable of individually controlling the supply and discharge of each refrigerant by adding a controller capable of individually controlling the first flow path part and the second flow path part of the flow path part. It is.

In order to achieve the above object of the present invention, the electrostatic chuck including a lower electrode according to an aspect of the present invention, the flow path portion through which the refrigerant flows inside the lower electrode;

And a coolant supply hole and a coolant discharge hole for supplying and discharging the coolant into the lower electrode, wherein the flow path part includes two or more flow path parts, and the two or more flow path parts are provided with an interface for dividing the flow path parts. Preferably, the coolant supply holes are two or more, and the coolant discharge holes are two or more.

In addition, two or more heat transfer plates are provided in the flow path parts.

In addition, the electrostatic chuck system having a lower electrode according to another aspect of the present invention, the flow path through which the refrigerant flows in the lower electrode, the refrigerant supply hole and the refrigerant discharge hole for supplying and discharging the refrigerant to the lower electrode and And a first refrigerant supply valve and a second refrigerant supply valve, a first refrigerant tank and a second refrigerant tank, a first sensor and a second sensor, and a control unit, wherein the flow path part includes two or more flow path parts. The two or more flow path parts are provided with an interface for dividing the flow path parts, the coolant supply holes are two or more and the coolant discharge holes are two or more, and the control unit separately supplies the coolant supply and the coolant discharge. It is desirable to control.

In addition, two or more heat transfer plates are provided in the flow path part.

(Example)

Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. However, embodiments of the present invention may be modified in various forms, and the scope of the present invention should not be interpreted to be limited by the embodiments described below. In addition, the embodiments of the present invention are only provided to those skilled in the art to more fully understand the present invention. Accordingly, it should be understood that the shapes shown in the figures have been exaggerated for simplicity and emphasis of description and unnecessary parts of the description have been omitted. In addition, in the present exemplary embodiment, two flow path parts are formed as the first and second flow path parts, but the two are shown for the sake of simplicity. It should be appreciated that the flow path part may be composed of two or more plurality of flow path parts.

Example 1

First, as shown in Figure 4, the electrostatic chuck according to an embodiment of the present invention includes a lower plate 411 of the lower electrode, the upper plate 421 of the lower electrode is bonded to the lower plate 411 and the upper plate On 421, an electrostatic sheet 407 including an electrode therein is bonded by an adhesive. Here, the lower electrode 420 is made of an aluminum-based material having excellent heat transfer efficiency as an electrode for generating plasma.

Bond between the electrostatic sheet 407 and the upper plate 421 of the lower electrode using a thermoplastic polyimide-based adhesive (not shown) having a thickness of 5 ~ 50um, the adhesion is low temperature compression treatment at a heating temperature of 100 ~ 250 ℃ To bond. Detailed description of the adhesive is disclosed in detail in Korean Patent Laid-Open Publication No. 2002-14722, and thus, specific details are omitted herein.

Subsequently, the structure of the electrostatic chuck according to the present application will be described. The lower plate 411 of the lower electrode includes two or more refrigerant supply holes 413 and 415 and two or more refrigerant discharge holes 412 and 414. In addition, the lower electrode upper plate 421 includes a plurality of small heat transfer plates 427, and includes two or more flow path parts, that is, a first flow path part 431 and a second flow path part 432. It has a defining interface 426. The electrostatic sheet 407 is bonded to the upper plate 421 of the lower electrode. Although not shown in the figure, a wafer to be processed is mounted on the electrostatic sheet 407.

5A and 5B, the holes of the coolant supply holes 513 and 515 and the coolant discharge holes 512 and 514 are configured to be larger than the flow path portion of each coolant passing between the heat transfer plates 527a and 527b. Here, although the heat transfer plates 427a and 427b shown in FIG. 5B are represented by three pillars formed in the flow path portion, those skilled in the art may form the heat transfer plates in plural or more. You will see that.

Subsequently, the operation of the electrostatic chuck according to the present application will be described.

As shown in FIGS. 5A and 5B, the refrigerant introduced through the first refrigerant supply hole 513 flows along the first flow path portion inside the interface 526 to remove heat from the plurality of heat transfer plates 527a. All. The refrigerant having a temperature rise is discharged through the first refrigerant discharge hole 512. In addition, the refrigerant introduced through the second refrigerant supply hole 515 flows along the second flow path portion outside the boundary surface 526 to remove heat from the plurality of heat transfer plates 527b. The refrigerant having the increased temperature is discharged through the second refrigerant discharge hole 514.

Therefore, the temperature of the edge portion and the center portion of the wafer can be kept uniform.                     

Example 2

In the present embodiment, the same components as those described in the first embodiment will be omitted, and only other components or added portions will be described.

In the electrostatic chuck system according to Embodiment 2 of the present invention, the structure of the lower electrode 200 is the same, and only the controller 630 capable of individually controlling the first flow path portion and the second flow path portion of the lower electrode, and a refrigerant supply The first sensor 661 and the second sensor 662 connected to the valves, the refrigerant discharge valves, and the first refrigerant tank 641 and the second refrigerant tank 642 which are commonly connected to the control unit 630. Additionally included.

6, the first refrigerant supply valve 653 is connected to the first refrigerant supply hole 613, and the first refrigerant supply valve 653 is connected to the first refrigerant tank 641. A heat supply for supplying a coolant to the first flow path part (Fig. 4; 431) is performed. In addition, a first refrigerant discharge valve 652 is connected to the first refrigerant discharge hole 612, and the refrigerant discharge valve 652 is connected to the first sensor 661 and the first refrigerant tank 641. The first sensor 661 is connected to the controller 630.

The second refrigerant supply valve 655 is connected to the second refrigerant supply hole 615, and the second refrigerant supply valve 655 is connected to the second refrigerant tank 642 so that the second flow path part (FIG. 4: 432). It serves to supply the refrigerant. In addition, a second refrigerant discharge valve 654 is connected to the second refrigerant discharge hole 614, and a second sensor 662 and a second refrigerant tank 642 are connected to the refrigerant discharge valve 654. The second sensor 662 is connected to the controller 630.

In this case, the first and second sensors 661 and 662 are disposed as close as possible to the first and second refrigerant discharge holes 614 and 612, respectively. The reason is that the coolant temperature may change when the coolant moves along the discharge holes to the coolant discharge valve, so that the coolant is installed as close to the coolant discharge holes as possible.

Subsequently, the operation of the electrostatic chuck system according to the second embodiment will be described. First, the refrigerant is supplied through the first and second refrigerant supply valves 653 and 655 connected to the first and second refrigerant tanks 641 and 642, respectively. And second flow path parts 431 and 432, respectively. The refrigerant deprives heat of the heat transfer plates (FIGS. 5: 527a and 527b) formed in the first and second flow path parts (FIGS. 4 and 431 and 432), and the refrigerant whose temperature rises due to the heat is the first and second refrigerant outlets, respectively. 612 and 614 return to the first and second refrigerant tanks 641 and 642 via the first and second refrigerant discharge valves 652 and 654, respectively. In this case, first and second sensors 661 and 662 respectively connected to the first and second refrigerant discharge valves 652 and 654 detect a temperature of the refrigerant returned to the refrigerant tanks, and thus, the first flow path part 431 and the second flow path. When a temperature difference of the refrigerant passing through the flow path part 432 occurs, the controller 630 individually instructs the refrigerant tanks 641 and 642 to adjust the flow and amount of the refrigerant.

Therefore, according to the above configuration, by detecting the temperature of the refrigerant flowing through the first flow path portion and the second flow path portion and individually controlled by the controller, even if the diameter of the wafer is 12 inches, the temperature of the edge portion and the center portion of the wafer are uniform. Can be controlled.

As described above in detail, the flow path portion formed inside the lower electrode of the electrostatic chuck constitutes the first and second flow path portions and forms an interface for separating the first flow path portion and the second flow path portion, thereby forming the flow path portion inside the lower electrode. It is possible to make the temperature of the flowing refrigerant extremely insignificant in the central portion and the edge portion.

In addition, the temperature of the refrigerant flowing through the first flow path portion and the second flow path portion formed in the lower electrode of the electrostatic chuck is respectively detected by the sensor and individually controlled by the controller, so that even if the diameter of the wafer is large, The temperature can be controlled uniformly.

As a result, ultimately, the manufacturing failure rate of the semiconductor device can be minimized and the reliability of the semiconductor device manufacturing apparatus can be improved.

Claims (4)

In the electrostatic chuck comprising an upper plate and a lower electrode made of a lower plate bonded to the upper plate, The upper plate is provided such that the central first flow path part and the second flow path part of the edge are arranged to be separated from each other by an interface, and the lower plate has refrigerant supply holes and refrigerant discharges connected to the first and second flow path parts. With holes, Each of the first and second flow path portions includes an outer flow passage portion and an inner flow passage portion having a letter 'C' shape, respectively, and central portions of the outer and inner flow passage portions are connected to the coolant supply hole and the coolant discharge hole, respectively. Electrostatic chuck characterized in that the one end of the outer and inner passages are connected to each other, the other end of the outer and inner passages are connected to each other. The electrostatic chuck of claim 1, wherein two or more heat transfer plates are installed in each of the first and second flow path parts. An electrostatic chuck system comprising an electrostatic chuck, a first refrigerant supply valve, a second refrigerant supply valve, a first refrigerant tank, a second refrigerant tank, a first sensor, a second sensor, and a controller, The electrostatic chuck includes a lower electrode consisting of an upper plate and a lower plate adhered to the upper plate, The upper plate is provided such that the central first flow path part and the second flow path part of the edge are arranged to be separated from each other by an interface, and the lower plate has refrigerant supply holes and refrigerant discharges connected to the first and second flow path parts. Holes are provided, Each of the first and second flow path portions includes an outer flow passage portion and an inner flow passage portion having a letter 'C' shape, respectively, and central portions of the outer and inner flow passage portions are connected to the coolant supply hole and the coolant discharge hole, respectively. One end of the outer and inner passages are connected to each other, the other end of the outer and inner passages are connected to each other, The first and second refrigerant tanks are connected to the first and second flow path portions through the refrigerant supply holes and the refrigerant discharge holes, respectively. The first and second sensors are disposed to be adjacent to the refrigerant discharge holes, The control unit is characterized in that for controlling the flow rate of the refrigerant separately in accordance with the temperature detected by the first and second sensors. 4. The electrostatic chuck system of claim 3, wherein two or more heat transfer plates are installed in each of the first and second flow path portions.

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