TW202306019A - Electrostatic chuck and plasma reaction device - Google Patents

Abstract

The invention provides an electrostatic chuck. The electrostatic chuck comprises a base; the first dielectric layer is arranged on the base and is made of a doped ceramic material with first resistivity, and an electrode for generating electrostatic force is arranged in the first dielectric layer; the second dielectric layer is arranged on the first dielectric layer and covers the first dielectric layer, and the second dielectric layer is made of an undoped ceramic material with second resistivity; the second resistivity is greater than the first resistivity. The invention also provides a plasma reaction device. The electrostatic chuck is high in adsorption force, uniform in adsorption force distribution, easy to desorb, long in service life and less in particulate matter pollution, helium sparking on the back surface of the wafer is effectively prevented, and the wafer processing yield and the production efficiency are improved.

Description

Electrostatic chuck and plasma reaction device

The invention relates to the technical field of semiconductors, in particular to an electrostatic chuck and a plasma reaction device.

In the manufacturing process of semiconductor components, in order to perform processes such as deposition and etching on the wafer, electrostatic chuck (ESC) is generally used to generate electrostatic attraction to support and fix the wafer to be processed during the process. .

An electrostatic chuck consists of a base and a dielectric layer disposed on top of the base. According to the different dielectric layers, electrostatic chucks are mainly divided into two types: CB (Coulomb Coulomb) type electrostatic chuck and J-R (Johnsen-Rahbek) type electrostatic chuck. CB type electrostatic chuck (referred to as CB ESC) and J-R type electrostatic chuck (abbreviated as J-R ESC) are based on the principle of electrostatic adsorption. After applying an external DC voltage to the electrodes in CB ESC and J-R ESC, the wafer will be generated. Electrostatic attraction to hold the wafer.

The electrostatic adsorption force of CB ESC is small, and a high DC voltage needs to be applied to its electrodes; however, when the applied DC voltage is too high, it will easily cause the problem of helium ignition between the wafer and CB ESC.

The leakage current of J-R ESC is large. After stopping the application of external DC voltage to the electrodes of J-R ESC, there are still many residual charges on the surface of J-R ESC, which makes it difficult to desorb the wafer; and the rough surface of J-R ESC is easy to be corroded, which is easy to cause particles Increase, use aging, poor surface roughness of J-R ESC, and short service life. At the same time, it will also cause the temperature of the wafer placed on the J-R ESC to be uneven, which will affect the processing accuracy of the wafer.

The purpose of the present invention is to provide an electrostatic chuck and a plasma reaction device. By combining dielectric layers with different resistivities, not only the service life of the electrostatic chuck can be improved, but also it is not necessary to apply a high DC voltage, which can prevent the backside of the wafer from Helium ignition occurs, and at the same time, the adsorption force is strong, the adsorption force is evenly distributed, and it is easy to desorb the wafer.

In order to achieve the above object, the present invention provides an electrostatic chuck, comprising: base; A first dielectric layer disposed on the base; the first dielectric layer is a doped ceramic material with a first resistivity, and electrodes for generating electrostatic force are arranged in the first dielectric layer; A second dielectric layer disposed on the first dielectric layer and covering the first dielectric layer; the second dielectric layer is an undoped ceramic material with a second resistivity; the second resistivity is greater than the first A resistivity.

Preferably, the first dielectric layer is doped AL ₂ O ₃ , and its dopant includes any one or more of Si, C, Mg, MgO, and TiO ₂ .

Preferably, the second dielectric layer is undoped AL ₂ O ₃ .

Preferably, the resistivity of the first dielectric layer is 10 ¹⁰ -10 ¹² Ω.cm.

Preferably, the resistivity of the second dielectric layer is greater than 10 ¹⁴ Ω.cm.

Preferably, the surface of the second dielectric layer in contact with the wafer is provided with a plurality of uniformly or non-uniformly distributed protrusions; the height of the protrusions ranges from 2 to 3 um.

Preferably, an adhesive layer for fixedly connecting the first and second dielectric layers is further provided between the first dielectric layer and the second dielectric layer.

Preferably, the thickness of the first dielectric layer is 0.2-2mm.

Preferably, the thickness of the second dielectric layer is 0.01-0.5 mm.

Preferably, the first dielectric layer has a surface roughness of 0.6-0.8um; the second dielectric layer has a surface roughness of 0.1-0.2um.

Preferably, the bottom of the first dielectric layer is bonded to the top of the base, and the periphery of the second dielectric layer extends downwards and completely covers the outer sidewall of the first dielectric layer.

Preferably, the first dielectric layer is embedded on the top of the base, and the top surface of the first dielectric layer is flush with the top surface of the base; the second dielectric layer is arranged on the base and completely covers the first dielectric layer.

Preferably, the outer wall of the base is provided with a plasma-resistant coating.

Preferably, a plurality of cooling pipes are arranged in the susceptor, and the cooling pipes include a helium channel through which the helium is passed to the gap between the wafer and the second dielectric layer, and the helium The channel avoids the raised portion.

The present invention also provides a plasma reaction device, comprising a plasma reaction chamber, the bottom of the plasma reaction chamber is provided with an electrostatic chuck according to the present invention, and the wafer to be processed is adsorbed by the electrostatic chuck.

Compared with prior art, the beneficial effect of the present invention is: 1) The electrostatic chuck of the present invention has strong adsorption force, uniform distribution of adsorption force, and easy desorption of wafers, which improves the production efficiency of wafer processing and the yield of wafers; 2) Since the first dielectric layer is covered with an undoped second dielectric layer, the generation of particle pollutants is reduced, and the adsorption force and temperature distribution of the electrostatic chuck are uniform, which not only further improves the yield of wafer processing , while also improving the service life of the electrostatic chuck, reducing the maintenance and manufacturing costs of the electrostatic chuck; 3) In the present invention, a doped and low-resistivity first dielectric layer is used, through the freely moving electrons in the first dielectric layer, the electrode position of the electrostatic chuck is "raised"; and because the second dielectric There is no need to set electrodes in the electrical layer, so that the second dielectric layer can have a smaller thickness, so only a small DC voltage needs to be applied to the electrodes in the electrostatic chuck to provide sufficient adsorption force for the wafer; 4) The electrostatic chuck of the present invention only needs to apply a small DC voltage when it works, so it can effectively prevent helium ignition on the back of the wafer, realize safe production, and further improve the yield of wafer processing.

The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some, not all, embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without making progressive changes fall within the protection scope of the present invention.

Embodiment one

Figure 1A shows a schematic structural view of the plasma reaction device used by the electrostatic chuck of the present invention. The plasma reaction device in Figure 1A is a capacitively coupled plasma (CCP) reaction device, and the electrostatic chuck of the present invention is also suitable for inductively coupled plasma body reaction device (ICP). The capacitively coupled plasma reaction device in FIG. 1A is a device for generating plasma in a reaction chamber by means of capacitive coupling from a radio frequency power source applied to a susceptor for etching. It includes a vacuum reaction chamber 100, the vacuum reaction chamber includes a substantially cylindrical reaction chamber side wall 101 made of metal material, and an opening 102 is provided on the reaction chamber side wall 101 for accommodating the entry and exit of wafers. A gas shower head 120 and a base 110 opposite to the gas shower head 120 are arranged in the vacuum reaction chamber 100 . The gas shower head 120 is connected with a gas supply device 125 for delivering reaction gas to the vacuum reaction chamber 100 and serving as an upper electrode of the vacuum reaction chamber 100 . The base 110 serves as the lower electrode of the vacuum reaction chamber 100, and a reaction area is formed between the upper electrode and the lower electrode. At least one radio frequency power source 150 is applied to one of the upper electrode or the lower electrode through the matching network 152, and a radio frequency electric field is generated between the upper electrode and the lower electrode to dissociate the reaction gas into plasma, and the plasma It contains a large number of active particles such as electrons, ions, excited atoms, molecules and free radicals. The above-mentioned active particles can undergo various physical and chemical reactions with the surface of the wafer to be processed, so that the morphology of the wafer surface changes, that is, Complete the etching process. An exhaust pump 140 is also provided below the vacuum reaction chamber 100 to discharge the reaction by-products out of the vacuum reaction chamber 100 to maintain the vacuum environment of the vacuum reaction chamber 100 .

The electrostatic chuck fixes the wafer W placed on it through electrostatic adsorption. Its advantage is that the adsorption is evenly distributed on the surface of the wafer, the wafer W will not warp and deform, and there will be no damage to the wafer W. Stable, can guarantee the machining accuracy of wafer W. As shown in FIG. 1A , FIG. 1B , and FIG. 2 , the electrostatic chuck of the present invention includes a base 110 , a first dielectric layer 111 , an electrode 113 , and a second dielectric layer 112 .

As shown in FIG. 1A, FIG. 1B, and FIG. 2, the first dielectric layer 111 is disposed on the base 110 (for example, the bottom of the first dielectric layer 111 is fixed on the top of the base 110 by bonding) , which is a doped ceramic material with a first resistivity. In an embodiment of the present invention, the first dielectric layer 111 is doped Al ₂ O ₃ , and its dopant includes any one or more of Si, C, Mg, MgO, and TiO ₂ . The first dielectric layer 111 can be processed by powder spraying, plasma CVD (chemical vapor deposition), etc., or can be machined by injection molding and sintering of ceramic powder. The resistivity of the first dielectric layer 111 is 10 ¹⁰ -10 ¹² Ω.cm. As a preferred embodiment of the present invention, the resistivity of the first dielectric layer 111 is 10 ¹¹ Ω.cm. In this embodiment, as shown in FIG. 1B and FIG. 2 , the thickness of the first dielectric layer 111 is d ₁ =0.2˜2 mm. The surface roughness of the first dielectric layer 111 is 0.6-0.8um.

As shown in FIG. 1A , FIG. 1B , and FIG. 2 , the electrode 113 is disposed in the first dielectric layer 111 for generating electrostatic force. In order to realize adsorption and fixation of the wafer W to be processed during the manufacturing process.

As shown in Fig. 1A, Fig. 1B and Fig. 2, the second dielectric layer 112 is arranged on the first dielectric layer 111, and the periphery of the second dielectric layer 112 extends downward (as indicated by the dotted circle in Fig. 2 shown) and completely cover the outer sidewall of the first dielectric layer 111. Therefore, the first dielectric layer 111 is disposed in a space surrounded by the base 110 and the second dielectric layer 112 .

Since the undoped Al ₂ O ₃ has the function of resisting plasma erosion, the first dielectric layer 111 is completely covered by the second dielectric layer 112, which can effectively prevent the dopant in the first dielectric layer 111 from being reacted The plasma in the chamber erodes, resulting in particulate contamination that adheres to the wafer W. Since no particle contamination is generated, the electrostatic chuck of the present invention can ensure that the temperature of the wafer W is uniform, and the adsorption force on the wafer W is also uniformly distributed.

An adhesive layer (not shown in the figure) is also provided between the first dielectric layer 111 and the second dielectric layer 112, through which the first dielectric layer 111 and the second dielectric layer are fixedly connected. 112.

The second dielectric layer 112 is an undoped ceramic material with a second resistivity. The resistivity of the second dielectric layer 112 is greater than 10 ¹⁴ Ω.cm. As a preferred embodiment of the present invention, the resistivity of the second dielectric layer 112 is 10 ¹⁷ Ω.cm. Since the resistivity of the second dielectric layer 112 is greater than that of the first dielectric layer 111 , it is also said that the second dielectric layer 112 has a high resistivity, and the first dielectric layer 111 has a low resistivity. In an embodiment of the present invention, the second dielectric layer 112 is undoped Al ₂ O ₃ , which may be processed by machining. As shown in FIG. 1B and FIG. 2 , in this embodiment, the thickness of the second dielectric layer 112 is d ₂ =0.1˜0.5 mm. The surface roughness of the second dielectric layer 112 is 0.1-0.2um.

The electrostatic chuck of the present invention can make the second dielectric layer 112 generate sufficient adsorption force on the wafer W without applying an excessively high DC voltage on the electrode 113 , and effectively prevent the helium gas on the back of the wafer W from sparking. Moreover, the electrostatic chuck of the present invention has a small leakage current, so it is very easy to detach the wafer W.

The following is a description of the principles of the present invention: The principle of electrostatic adsorption is that when a charged object is close to another uncharged object, due to the effect of electrostatic induction, the side of the uncharged object close to the charged object will gather charges of the opposite polarity to that of the charged object (while in The other side produces the same number of charges of the same sex as the charged object), due to the mutual attraction between the opposite charges on the two surfaces in contact, the two objects will have an attractive force, that is, "electrostatic adsorption".

A common electrostatic chuck usually includes: a base made of thermally conductive material, a dielectric layer disposed on the base, and electrodes disposed in the dielectric layer. The properties of the dielectric layer have an important influence on the adsorption force, desorption capacity and service life of the electrostatic chuck.

As shown in Figure 3, the electrostatic chuck uses a dielectric layer 112' with a relatively high resistivity (the resistance level is 10 ⁹ Ohm), and an electrode 113' is arranged in the dielectric layer 112', and the electrostatic chuck is not shown in Figure 3. The base of the suction cup. As shown in FIG. 3 , the dielectric layer 112 ′ is roughly disc-shaped, and its diameter is slightly smaller than the diameter of the wafer W adsorbed thereon, so as to ensure that the wafer W completely covers the dielectric layer 112 ′ and prevent the plasma from affecting the dielectric layer 112 ′. The electrical layer 112' causes damage. When electrostatic attraction is generated, the wafer W acts as an upper electrode, and the electrode 113' acts as a lower electrode. Since the dielectric layer 112' has a relatively high resistivity, the dielectric layer 112' has absolute insulation, and there are very few free-moving electrons therein, and only polarized charges can be generated. An external DC voltage (positive voltage in Figure 3) is applied to the lower electrode, so that a potential difference is generated between the upper electrode (wafer W) and the lower electrode, through which the wafer W is attracted to the electrostatic chuck .

；  （1） The calculation formula of the adsorption force F _chunk1 of this electrostatic chuck is as follows:

; (1)

Wherein, ɛ is the relative permittivity of the insulating dielectric layer, ɛ ₀ is the vacuum permittivity, V is the DC voltage volts applied to the lower electrode, and d is the distance between the lower electrode and the bottom of the wafer.

According to formula (1), it can be seen that F _chunk1 is inversely proportional to the second power of d . Since the electrode 113' needs to be arranged inside the dielectric layer 112', and the mechanical strength and flatness of the dielectric layer 112' need to be ensured, the processing of the dielectric layer 112' is difficult, and the dielectric layer 112' should not be too thin (usually The insulating dielectric layer 112' is set to 2 mm). The greater the thickness of the dielectric layer 112 ′, the smaller the electrostatic adsorption force F _chunk1 , so that a high DC voltage (about 2000 volts) is required to provide sufficient adsorption force for the wafer W.

In semiconductor processing, the heat dissipation of the wafer W is very important. If the uniform temperature of the surface of the wafer W cannot be guaranteed, the uniformity of processing cannot be ensured during the processing of the wafer W, and the processing accuracy will be greatly affected. Generally, by improving the heat dissipation of the backside of the wafer W, the local high temperature can be dissipated immediately, so as to ensure the uniform temperature of the surface of the wafer W. This method relies on the electrostatic chuck to conduct heat on the wafer W to dissipate heat, and the heat dissipation effect mainly depends on the material of the electrostatic chuck.

Another method for dissipating heat from the wafer W is to increase the gas convection on the surface of the wafer W, and use the method of gas convection to dissipate heat to even out the temperature of the surface of the wafer W. Contained within the pedestal 110 is a first channel (not shown in FIG. 3 ) for routing a thermally conductive gas, such as helium, to the pedestal, dielectric layer 112 ′. The dielectric layer 112' is also pierced with a plurality of second channels (not shown in FIG. 3 ) communicating with the first channels, for delivering the heat-conducting gas to the upper surface of the dielectric layer 112' and the crystal. Between the bottom surfaces of the wafer W, the heat transfer between the wafer W and the dielectric layer 112' is promoted. As shown in FIG. 1A and FIG. 1B , a coolant channel is also provided inside the base 110 for controlling the temperature of the base 110 .

Since the dielectric layer 112' needs to have a thickness of about 2 mm, the internal electrode 113' must be connected to a DC high voltage to provide sufficient adsorption force for the wafer, and the high voltage applied to the electrode 113' will bring the wafer W risk of helium sparking on the back side.

The electrostatic chuck as shown in FIG. 4 uses a dielectric layer 112'' with a lower resistivity (the resistance of the dielectric layer 112'' is on the order of 10 ⁶ Ohm). The base of the electrostatic chuck is not shown in FIG. 4 . In FIG. 4, an electrode 113'' is disposed inside the dielectric layer 112''. The dielectric layer 112'' is not an ideal insulating medium, that is, there are many electrons that can move freely in the dielectric layer 112'', so that the dielectric layer 112'' has a finite resistance. After applying a voltage (positive voltage in FIG. 4 ) to the electrode 113'' in the dielectric layer 112'', the mobile particles in the dielectric layer 112'' are affected by the electrode 113'' so that electron migration gathers in the dielectric layer 112''. The lower surface of the dielectric layer 112'', while the positively charged particles gather on the upper surface of the dielectric layer 112''. That is, the electrostatic chuck shown in FIG. 4 conducts positive charges to the upper surface of the electrostatic chuck through leakage current.

As shown in FIG. 4 , since the upper surface of the dielectric layer 112 ″ is not an ideal plane, its roughness cannot be ignored, and a plurality of “peaks” and “valleys” are formed on the upper surface of the dielectric layer 112 ″. Due to the "tip effect", positively charged particles gather at the "mountain". A micro electric field is formed between the “mountain” and the negative electrons on the back of the wafer W. The electric field force generated by countless miniature electric fields constitutes the adsorption force of the electrostatic chuck. The electric field strength of the miniature electric field increases with the increase of the DC voltage applied to the electrode 113''.

；  （2） 其中，

為真空介電常數， V _gap 為所述“山峰”與晶圓W的背面之間的電勢差， d _gap 為微型電場的“山峰”與晶圓W的背面之間的距離。基於晶圓W的實際面積S，通過對公式（2）進行求積分運算，即可得到圖4中靜電吸盤的吸附力 F _chunk3 ：

。 The calculation formula of the electric field force F _chunk2 of the micro electric field is as follows:

; (2) where,

is the vacuum dielectric constant, V _gap is the potential difference between the "mountain" and the back of the wafer W, and d _gap is the distance between the "mountain" of the micro electric field and the back of the wafer W. Based on the actual area S of the wafer W, the adsorption force F _chunk3 of the electrostatic chuck in Figure 4 can be obtained by integrating the formula (2):

.

Since the d _gap is usually only 1-2um, it only needs to apply a small DC voltage (700-1000V) to the electrode 113'' to generate sufficient adsorption force, so the adsorption force of the electrostatic chuck shown in Figure 4 is much greater than that shown in Figure 4. The adsorption force of the electrostatic chuck shown in Figure 3, the electrostatic chuck shown in Figure 4 is usually used in the semiconductor industry.

But at the same time, the electrostatic chuck in Figure 4 also has significant disadvantages: 1) After the application of DC voltage to the electrode 113'' of the electrostatic chuck is stopped, the charge of the "mountain" is still difficult to release, thus causing the problem of difficulty in desorbing the wafer W; 2) When the charge of the "mountain" accumulates too much, it will discharge the wafer W and cause damage to the wafer W; 3) The adsorption force of the electrostatic chuck will change greatly with the temperature change, so the adsorption force is not stable enough; 4) Since the dielectric layer 113'' of the electrostatic chuck is doped, the dopant is easily eroded by the plasma in the vacuum reaction chamber. In use, the life of the electrostatic chuck is short, and it is easy to generate particle contamination, which may easily cause wafer damage. There are a series of problems such as uneven temperature of W and uneven distribution of adsorption force.

具有更小的厚度。即使該厚度可達0.01mm。根據公式（1），由於第二介電層112的厚度減小，本發明的靜電吸盤僅需較小的直流電壓（低於2000V），即可為晶圓W提供足夠的吸附力。當施加的直流電壓減小時，晶圓W的背面氦氣打火的隱患則自然被消除。 In the present invention, the above-mentioned problems and disadvantages are overcome by using two dielectric layers having different resistivities. As shown in FIG. 2 , in the present invention, due to the low resistivity of the first dielectric layer 111 , many electrons can move freely inside it. In FIG. 2 , a positive voltage is applied to the electrode 113 in the first dielectric layer 111 . When a positive voltage is applied to the electrodes 113 in the first dielectric layer 111 , the freely moving electrons gather on the lower surface of the first dielectric layer 111 . Positively charged particles gather on the upper surface of the first dielectric layer 111 . The positively charged particles on the upper surface of the first dielectric layer 111 generate electrostatic induction with the lower surface of the second dielectric layer 112, so the lower surface of the second dielectric layer 112 generates negatively charged polarized charges, and the second dielectric layer 112 The upper surface of layer 112 generates a positive polarized charge. Due to electrostatic induction, negative charges are accumulated on the back side of the wafer W, and the mutual attraction between the lower surface of the wafer W and the upper surface of the second dielectric layer 112 will make the second dielectric layer 112 opposite to the wafer. Circle W creates attraction. That is to say, it is equivalent to "lifting" the position of the electrode 113 into the second dielectric layer 112, but actually it is not necessary to arrange the electrode 113 in the second dielectric layer 112, so that the second dielectric layer 112 attracts the wafer W by its polarized charge. Since the second dielectric layer 112 does not need to be provided with electrodes 113, the second dielectric layer 112 of the present invention can be compared with the dielectric layer of the electrostatic chuck shown in FIG.

Has a smaller thickness. Even if the thickness can reach 0.01mm. According to the formula (1), due to the reduced thickness of the second dielectric layer 112 , the electrostatic chuck of the present invention only needs a small DC voltage (less than 2000V) to provide sufficient adsorption force for the wafer W. When the applied DC voltage is reduced, the hidden danger of helium sparking on the back side of the wafer W is naturally eliminated.

The leakage current of the electrostatic chuck of the present invention is determined by the total resistance of the first dielectric layer 111 and the second dielectric layer 112 . The resistance of the first dielectric layer 111 is on the order of MOhm, and the resistance of the second dielectric layer 112 is on the order of GOhm. Therefore, by combining the first dielectric layer 111 with the second dielectric layer 112, compared with the electrostatic chuck shown in FIG. 4, the electrostatic chuck of the present invention can significantly reduce the leakage current, and it is easier to desorb the wafer W. .

In some other embodiments, a negative voltage may also be applied to the electrodes 113 in the first dielectric layer 111 . When a negative voltage is applied, electrons in the first dielectric layer 111 are moved and collected on the upper surface of the first dielectric layer 111 by the action of the electrode 113 , while positively charged particles are collected on the lower surface of the first dielectric layer 111 . That is, the negative charge is conducted to the upper surface of the first dielectric layer 111 through the leakage current. Meanwhile, the polarized charges on the lower surface of the second dielectric layer 112 are positive charges, and the polarized charges on the upper surface of the second dielectric layer 112 are negative charges. Positive charges are accumulated on the back side of the wafer W by electrostatic induction. In this way, a potential difference is generated between the wafer W and the second dielectric layer 112 for attracting the wafer W.

As shown in FIG. 7 , the surface of the second dielectric layer 112 in contact with the wafer W is provided with a plurality of uniformly or non-uniformly distributed protrusions 1121 ; the height of the protrusions 1121 ranges from 2 to 3 μm. Compared with completely contacting the wafer W through the plane, the second dielectric layer 112 reduces the contact area with the wafer W through the plurality of protrusions 1121 , which can facilitate and quickly desorb the wafer W. At the same time, a certain gap is formed between the wafer W and the second dielectric layer 112 through the protruding portion 1121 . When a heat-conducting gas (such as helium) is injected into the gap, the heat of the wafer W can be taken away through the heat transfer between the heat-conducting gas and the wafer W.

A plurality of cooling channels are also provided in the base 110 of the present invention, and the cooling channels include a helium channel 114 . As shown in FIG. 7 , the helium gas is passed to the gap between the wafer W and the second dielectric layer 112 through the helium gas channel 114 , and the helium gas channel 114 avoids the raised portion 1121 .

Embodiment two

As shown in FIG. 5, in this embodiment, the first dielectric layer 211 is embedded on the top of the base 210, and the top surface of the first dielectric layer 211 is flush with the top surface of the base 210; The electrical layer 212 is disposed on the base 210 and completely covers the first dielectric layer 211 . The first dielectric layer 211 is located in the space surrounded by the second dielectric layer 212 and the base 210 to prevent the dopant in the first dielectric layer 211 from being eroded by the plasma to produce pollutants.

Embodiment Three

As shown in FIG. 6 , in this embodiment, the outer wall of the base 310 is provided with a plasma-resistant coating 314 . The coating film 314 protects the base 310 from plasma erosion in the vacuum reaction chamber, and further reduces the generation of particle pollutants. It is beneficial to improve the yield of wafer W processing.

The present invention also provides a plasma reaction device, including a plasma reaction chamber, the bottom of the plasma reaction chamber is provided with an electrostatic chuck as described in the present invention (above), and the wafer W to be processed is adsorbed by the electrostatic chuck .

In the present invention, the second dielectric layer 112 of high-resistivity non-doped ceramic material completely covers the first dielectric layer 111 of low-resistivity doped ceramic material, and is arranged in the first dielectric layer 111 The electrode 113 realizes “elevating” the position of the electrode 113 , and the second dielectric layer 112 can generate electrostatic attraction to the wafer W without disposing the electrode 113 in the second dielectric layer 112 . Since the second dielectric layer 112 does not contain the electrode 113, the second dielectric layer 112 is thinner than the high-resistivity material dielectric layer used in the prior art, and the second dielectric layer 112 can be made without applying an excessively high DC voltage. The second dielectric layer 112 produces sufficient adsorption force and effectively prevents the helium gas from sparking on the back of the wafer W. Further, since the electrostatic chuck of the present invention has a smaller leakage current than the electrostatic chuck using a high-resistivity material dielectric layer in the prior art, it is easier to detach the wafer W.

Therefore, the electrostatic chuck of the present invention has the advantages of being easy to desorb and does not need to apply a high DC voltage, and is not easily eroded by plasma, has a longer service life, and can effectively prevent helium ignition, greatly improving production efficiency , and improve the success rate of wafer processing.

The above is only a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Anyone familiar with the technical field who has ordinary knowledge can easily think of various other methods within the technical scope disclosed in the present invention. Any effective modification or replacement shall fall within the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the patent application scope.

100: vacuum reaction chamber 101: Reaction cavity wall 102: opening 110,210,310: base 111,211: first dielectric layer 112,311: second dielectric layer 1121: Raised part 113: electrode 114: Helium channel 120: Gas sprinkler head 125: gas supply device 140: exhaust pump 150: RF power supply 152:Matching network 314: coating W: Wafer

In order to illustrate the technical solution of the present invention more clearly, the accompanying drawings that need to be used in the description will be briefly introduced below. Obviously, the accompanying drawings in the following description are an embodiment of the present invention, and have common knowledge in the technical field For the knowledgeable, other drawings can also be obtained from these drawings without making progressive changes: FIG. 1A is a schematic diagram of a plasma reaction device applied to an electrostatic chuck of the present invention in Embodiment 1; FIG. 1B and FIG. 2 are schematic structural diagrams of the electrostatic chuck of the present invention in Embodiment 1; Fig. 3 is a schematic diagram of the working principle of an electrostatic chuck using only a high-resistivity material dielectric layer; Fig. 4 is a schematic diagram of the working principle of an electrostatic chuck using only a low-resistivity material dielectric layer; Fig. 5 is a schematic structural diagram of the electrostatic chuck of the present invention in Embodiment 2; Fig. 6 is a schematic structural diagram of the electrostatic chuck of the present invention in Embodiment 3; and FIG. 7 is a schematic diagram of passing heat conduction gas to the gap between the wafer and the second dielectric layer through the helium gas channel.

110: Base

111: the first dielectric layer

112: second dielectric layer

113: electrode

W: Wafer

Claims (15)

An electrostatic chuck, including: a base; A first dielectric layer, which is arranged on the base; the first dielectric layer is a doped ceramic material with a first resistivity, and a device for generating electrostatic force is arranged in the first dielectric layer electrodes; and A second dielectric layer, which is arranged on the first dielectric layer and covers the first dielectric layer; the second dielectric layer is an undoped ceramic material with the second resistivity; the second The resistivity is greater than the first resistivity. The electrostatic chuck according to claim 1, wherein the first dielectric layer is doped AL ₂ O ₃ , and its dopant includes any one or more of Si, C, Mg, MgO, and TiO ₂ . The electrostatic chuck as claimed in claim 1, wherein the second dielectric layer is undoped AL ₂ O ₃ . The electrostatic chuck according to claim 1, wherein the resistivity of the first dielectric layer is 10 ¹⁰ -10 ¹² Ω.cm. The electrostatic chuck as claimed in claim 1, wherein the resistivity of the second dielectric layer is greater than 10 ¹⁴ Ω.cm. The electrostatic chuck according to claim 1, wherein the surface of the second dielectric layer in contact with the wafer is provided with a plurality of uniformly or non-uniformly distributed protrusions; the height of the protrusions ranges from 2 to 3 um. The electrostatic chuck according to claim 1, wherein an adhesive for fixedly connecting the first dielectric layer and the second dielectric layer is further provided between the first dielectric layer and the second dielectric layer layer. The electrostatic chuck as claimed in claim 1, wherein the thickness of the first dielectric layer is 0.2-2mm. The electrostatic chuck as claimed in claim 1, wherein the thickness of the second dielectric layer is 0.01-0.5 mm. The electrostatic chuck as claimed in claim 1, wherein the first dielectric layer has a surface roughness of 0.6-0.8um; the second dielectric layer has a surface roughness of 0.1-0.2um. The electrostatic chuck as claimed in claim 1, wherein the bottom of the first dielectric layer is bonded to the top of the base, and the periphery of the second dielectric layer extends downward and completely covers the outside of the first dielectric layer wall. The electrostatic chuck as claimed in claim 1, wherein the first dielectric layer is embedded on the top of the base, and the top surface of the first dielectric layer is flush with the top surface of the base; the second The dielectric layer is disposed on the base and completely covers the first dielectric layer. The electrostatic chuck as claimed in claim 1, wherein the outer wall of the base is provided with a coating film resistant to plasma corrosion. The electrostatic chuck as claimed in claim 6, wherein a plurality of cooling channels are arranged in the susceptor, and the cooling channels include a helium channel through which the helium gas is passed to the wafer and the second dielectric The gap between the layers, and the helium channel avoids the raised portion. A plasma reaction device, comprising a plasma reaction chamber, wherein the bottom of the plasma reaction chamber is provided with an electrostatic chuck according to any one of Claims 1 to 14, and the wafer to be processed is adsorbed by the electrostatic chuck.

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