TWI823273B - Electrostatic chuck and plasma reaction device - Google Patents

Abstract

The invention provides an electrostatic chuck, which includes: a base; a first dielectric layer disposed on the base, which is a doped ceramic material with a first resistivity, and an electrostatic chuck is provided in the first dielectric layer to generate electrostatic force Electrode; a second dielectric layer disposed on the first dielectric layer and covering the first dielectric layer, and the second dielectric layer is an undoped ceramic material with a second resistivity; the second resistivity is greater than the first dielectric layer Resistivity. The invention also provides a plasma reaction device. The electrostatic chuck of the present invention has strong adsorption force, uniform adsorption force distribution, easy desorption, long service life, and less particle pollution. It can effectively prevent helium sparking on the back of the wafer and improve the wafer processing yield and production efficiency.

Description

Electrostatic chuck and plasma reaction device

The invention relates to the technical field of semiconductors, and 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, an electrostatic chuck (ESC) is generally used to generate electrostatic suction to support and fix the wafer to be processed during the process. .

The electrostatic chuck includes 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) type electrostatic chuck and J-R (Johnsen-Rahbek) type electrostatic chuck. CB type electrostatic chuck (abbreviated as CB ESC) and J-R type electrostatic chuck (abbreviated as J-R ESC) are based on the basic principle of electrostatic adsorption. By applying an external DC voltage to the electrodes in CB ESC and J-R ESC, they generate a force on the wafer. Electrostatic adsorption force to fix the wafer.

CB ESC has a small electrostatic adsorption force and requires a high DC voltage to be applied to its electrode. However, when the applied DC voltage is too high, it can easily cause helium sparks between the wafer and CB ESC.

The leakage current of J-R ESC is large. After the external DC voltage is stopped applying to the electrode of J-R ESC, there is still a lot of residual charge on the surface of J-R ESC, making it difficult to desorb the wafer. Moreover, the rough surface of J-R ESC is easily eroded and can easily cause particulate matter. Increased use, aging, deterioration of J-R ESC surface roughness, and shortened service life. At the same time, it will also cause uneven temperature of the wafer placed on the J-R ESC, affecting 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, it can not only improve the service life of the electrostatic chuck, but also eliminate the need to apply a higher DC voltage and prevent the back side of the wafer. Helium ignition occurs, while 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, including: base; A first dielectric layer provided on the base; the first dielectric layer is a doped ceramic material with a first resistivity, and an electrode that generates electrostatic force is provided 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 second dielectric layer. -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 to 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 3um.

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 0.2-2 mm.

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 downward and completely covers the outer side wall of the first dielectric layer.

Preferably, the first dielectric layer is embedded and disposed 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 disposed on the base and completely covers the first dielectric layer. dielectric layer.

Preferably, the outer wall of the base is provided with a coating that is resistant to plasma corrosion.

Preferably, a plurality of cooling pipes are provided in the base, the cooling pipes include helium gas channels, and helium gas is passed through the helium gas channels to the gap between the wafer and the second dielectric layer, and the helium gas The channel avoids the projection.

The invention also provides a plasma reaction device, which includes a plasma reaction chamber. The bottom of the plasma reaction chamber is provided with an electrostatic chuck as described in the invention, and the wafer to be processed is adsorbed by the electrostatic chuck.

Compared with the conventional technology, the beneficial effects of the present invention are: 1) The electrostatic chuck of the present invention has strong adsorption force, uniform adsorption force distribution, and is easy to desorb wafers, thereby improving the production efficiency and wafer yield of wafer processing; 2) Since the first dielectric layer is covered with an undoped second dielectric layer, the generation of particulate pollutants is reduced, making the adsorption force and temperature distribution of the electrostatic chuck uniform, which not only further improves the yield of wafer processing , while also improving the service life of the electrostatic chuck and 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 to "raise" the electrode position of the electrostatic chuck through the freely moving electrons in the first dielectric layer; and due to the second dielectric There is no need to install electrodes in the electrical layer, so that the second dielectric layer can have a smaller thickness. Therefore, 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 working, so it can effectively prevent helium ignition on the back of the wafer, achieve safe production, and further improve the yield of wafer processing.

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those with ordinary skill in the art without making any progressive changes shall fall within the scope of protection of the present invention.

Embodiment 1

Figure 1A shows a schematic structural diagram of a plasma reaction device used in the electrostatic chuck of the present invention. The plasma reaction device in Figure 1A is a capacitively coupled plasma (CCP) reaction device. The electrostatic chuck of the present invention is also suitable for inductively coupled plasma. In vivo reaction device (ICP). The capacitively coupled plasma reaction device in Figure 1A is a device that generates plasma in a reaction chamber through capacitive coupling using a radio frequency power supply applied to a base and is used for etching. It includes a vacuum reaction chamber 100. The vacuum reaction chamber includes a generally cylindrical reaction chamber side wall 101 made of metal material. An opening 102 is provided on the reaction chamber side wall 101 to accommodate the entry and exit of the wafer. A gas shower head 120 and a base 110 opposite to the gas shower head 120 are disposed in the vacuum reaction chamber 100 . The gas shower head 120 is connected to 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 supply 150 is applied to one of the upper electrode or the lower electrode through the matching network 152 to generate a radio frequency electric field between the upper electrode and the lower electrode to dissociate the reaction gas into plasma. Plasma It contains a large number of active particles such as electrons, ions, excited atoms, molecules and free radicals. The above active particles can undergo various physical and chemical reactions with the surface of the wafer to be processed, causing the morphology of the wafer surface to change, 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 and maintain the vacuum environment of the vacuum reaction chamber 100 .

The electrostatic chuck uses electrostatic adsorption to fix the wafer W placed on it. Its advantage is that the adsorption effect is evenly distributed on the surface of the wafer. The wafer W will not warp and deform, and will not cause damage to the wafer W. The adsorption force is continuous. It is stable and can ensure the processing accuracy of wafer W. As shown in FIGS. 1A, 1B, and 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 Figure 1A, Figure 1B, and Figure 2, the first dielectric layer 111 is provided on the base 110 (for example, the bottom of the first dielectric layer 111 is fixed to the top of the base 110 by adhesive) , which is a doped ceramic material with a first resistivity. In the 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), or other methods, or it can be machined after injection molding and sintering of ceramic powder. The resistivity of the first dielectric layer 111 is 10 ¹⁰ to 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 provided in the first dielectric layer 111 for generating electrostatic force. In order to realize the adsorption and fixation of the wafer W to be processed during the manufacturing process.

As shown in Figures 1A, 1B, and 2, the second dielectric layer 112 is disposed on the first dielectric layer 111, and the periphery of the second dielectric layer 112 extends downward (as indicated by the dotted circle in Figure 2 (shown) and completely covers the outer side wall of the first dielectric layer 111. Therefore, the first dielectric layer 111 is disposed in the space surrounded by the base 110 and the second dielectric layer 112 .

Since undoped AL ₂ O ₃ is resistant to plasma erosion, completely covering the first dielectric layer 111 with the second dielectric layer 112 can effectively prevent the dopants in the first dielectric layer 111 from being reacted. The plasma in the cavity erodes, causing particle contaminants to adhere to the wafer W. Since no particulate pollutants are produced, 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 the resistivity of the first dielectric layer 111, it is also said that the second dielectric layer 112 has high resistivity and the first dielectric layer 111 has low resistivity. In the embodiment of the present invention, the second dielectric layer 112 is undoped AL ₂ O ₃ , which may be formed 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 to the wafer W without applying an excessively high DC voltage to the electrode 113, and effectively prevent helium gas ignition on the back side of the wafer W. Moreover, the electrostatic chuck of the present invention has a small leakage current, so it is very easy to desorb the wafer W.

The following is a description of the principle 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 accumulate charges of opposite polarity to the charge of the charged object (while on the side of the uncharged object close to the charged object) The other side generates the same number of charges (with the same charge as the charged object). Due to the mutual attraction between opposite charges on the two surfaces in contact, the two objects will generate an attraction, that is, "electrostatic adsorption".

Ordinary electrostatic chucks usually include: 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 impact on the adsorption force, desorption ability, and service life of the electrostatic chuck.

As shown in Figure 3, the electrostatic chuck uses a dielectric layer 112' with a higher resistivity (resistance magnitude is 10 ⁹ Ohm), and an electrode 113' is provided in the dielectric layer 112'. Figure 3 does not show the electrostatic chuck. The base of the suction cup. As shown in Figure 3, the dielectric layer 112' is roughly disk-shaped, and its diameter is slightly smaller than the diameter of the wafer W adsorbed on it to ensure that the wafer W completely covers the dielectric layer 112' and prevent plasma from damaging the dielectric layer. The electrical layer 112' causes damage. When the electrostatic attraction force is generated, the wafer W serves as the upper electrode and the electrode 113' serves as the lower electrode. Since the dielectric layer 112' has a high resistivity, the dielectric layer 112' has absolute insulation. There are very few electrons that can move freely in the dielectric layer 112' and can only generate polarization charges. An external DC voltage (positive voltage in Figure 3) is applied to the lower electrode, thus generating a potential difference between the upper electrode (wafer W) and the lower electrode. Through this potential difference, the wafer W is adsorbed on the electrostatic chuck. .

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

Among them, ɛ is the relative dielectric constant of the insulating dielectric layer, ɛ ₀ is the vacuum dielectric constant, V is the DC voltage 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 square of d . Since the electrode 113' needs to be provided 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' cannot be too thin (usually The insulating dielectric layer 112' is set to 2mm). The greater the thickness of the dielectric layer 112', the smaller the electrostatic adsorption force F _chunk1 , so that a very 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 ensured, the processing uniformity cannot be ensured during the processing of the wafer W, and the processing accuracy will be greatly affected. Usually, the heat dissipation of the backside of the wafer W is improved so that the local high temperature can be dissipated immediately to ensure the uniform temperature of the surface of the wafer W. This method relies on the electrostatic chuck to conduct heat to the wafer W to dissipate heat, and the heat dissipation effect mainly depends on the material of the electrostatic chuck.

Another method of heat dissipation of the wafer W is to increase the gas convection on the surface of the wafer W, and use the gas convection heat dissipation method to even out the temperature of the surface of the wafer W. Contained within the base 110 is a first channel (not shown in Figure 3) for routing a thermally conductive gas, such as helium, to the base, dielectric layer 112'. The dielectric layer 112' is also provided with a plurality of second channels (not shown in Figure 3) connected to the first channels for transporting the heat-conducting gas to the upper surface of the dielectric layer 112' and the crystal. between the bottom surfaces of the circles W, promoting heat transfer between the wafer W and the dielectric layer 112'. As shown in FIGS. 1A and 1B , a cooling fluid channel is 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 electrode 113' inside it must be connected to a DC high voltage to provide sufficient adsorption force for the wafer. The high voltage applied to the electrode 113' will cause the wafer W to Risk of helium ignition on the back.

The electrostatic chuck in Figure 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 Figure 4 . In Figure 4, an electrode 113'' is provided 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 finite resistance. After applying a voltage to the electrode 113'' in the dielectric layer 112'' (positive voltage in Figure 4), the movable particles in the dielectric layer 112'' are acted upon by the electrode 113'', causing electron migration to accumulate in the dielectric layer. The lower surface of layer 112'', while the positively charged particles accumulate on the upper surface of dielectric layer 112''. That is, the electrostatic chuck shown in Figure 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 and its roughness cannot be ignored, multiple “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 "peaks". A micro electric field is formed between the “peaks” and the negative electrons on the back side of the wafer W. The electric field force generated by countless micro electric fields constitutes the adsorption force of the electrostatic chuck. The electric field intensity of the micro electric field increases as the DC voltage applied to the electrode 113'' increases.

The calculation formula of the electric field force F _chunk2 of the micro electric field is as follows: ; (2) Among them, is the vacuum dielectric constant, V _gap is the potential difference between the “peak” and the back surface of the wafer W, and d _gap is the distance between the “peak” of the micro electric field and the back surface of the wafer W. Based on the actual area S of the wafer W, by integrating formula (2), the adsorption force F _chunk3 of the electrostatic chuck in Figure 4 can be obtained: .

Since 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. Therefore, the adsorption force of the electrostatic chuck shown in Figure 4 is much larger than that in Figure 4. 3 shows the adsorption force of the electrostatic chuck. The semiconductor industry usually uses the electrostatic chuck as shown in Figure 4.

But at the same time, the electrostatic chuck in Figure 4 also has significant shortcomings: 1) After stopping the application of DC voltage to the electrode 113'' of the electrostatic chuck, the charge on the "peak" is still difficult to release, thus causing the problem of difficulty in desorbing the wafer W; 2) When the charge on the "peak" accumulates too much, it will discharge the wafer W and cause damage to the wafer W; 3) The adsorption force of this electrostatic chuck also changes greatly with temperature changes, so the adsorption force is not stable enough; 4) Since the dielectric layer 113'' of the electrostatic chuck is doped, the dopants are easily eroded by the plasma in the vacuum reaction chamber. During use, the electrostatic chuck has a short lifespan and is prone to particle pollution, which can easily lead to wafer failure. There are a series of problems such as uneven temperature of W and uneven distribution of adsorption force.

In the present invention, the above problems and deficiencies are overcome by using two dielectric layers with different resistivities. As shown in FIG. 2 , in the present invention, since the resistivity of the first dielectric layer 111 is low, there are many electrons that can move freely inside the first dielectric layer 111 . 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 electrode 113 in the first dielectric layer 111, the above-mentioned 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 negative polarization charges, and the second dielectric layer 111 generates electrostatic induction. The upper surface of layer 112 generates a positively charged polarizing charge. Due to electrostatic induction, negative charges accumulate on the back side of the wafer W. Through the mutual attraction between the opposite charges on the lower surface of the wafer W and the upper surface of the second dielectric layer 112, the second dielectric layer 112 will be opposite to the wafer W. The circle W creates attraction. That is to say, it is equivalent to "raising" the position of the electrode 113 into the second dielectric layer 112. In fact, there is no need to set the electrode 113 in the second dielectric layer 112 to make the second dielectric layer 112 attracts wafer W through its polarization charge. Since the electrode 113 does not need to be provided inside the second dielectric layer 112 , the second dielectric layer 112 of the present invention can be compared with the dielectric layer of the electrostatic chuck shown in FIG. 3 Has a smaller thickness. Even the thickness can reach 0.01mm. According to 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 ignition on the backside of wafer W is naturally eliminated.

The leakage current of the electrostatic chuck of the present invention is determined by the total resistance value 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 and 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 desorb the wafer W more easily. .

In other embodiments, a negative voltage may also be applied to the electrode 113 in the first dielectric layer 111 . When a negative voltage is applied, the electrons in the first dielectric layer 111 are moved by the electrode 113 and gather on the upper surface of the first dielectric layer 111 , while the positively charged particles gather on the lower surface of the first dielectric layer 111 . That is, negative charges are conducted to the upper surface of the first dielectric layer 111 through leakage current. At the same time, the polarization charge on the lower surface of the second dielectric layer 112 is positive charge, and the polarization charge on the upper surface of the second dielectric layer 112 is negative charge. Positive charges accumulate on the back surface of wafer W through electrostatic induction. In this way, a potential difference is generated between the wafer W and the second dielectric layer 112 for adsorbing 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 distributed 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 a flat surface, 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 raised portion 1121 . When a thermally conductive gas (such as helium) is injected into the gap, the heat of the wafer W can be taken away through heat transfer between the thermally conductive gas and the wafer W.

A plurality of cooling ducts are also provided in the base 110 of the present invention, and the cooling ducts include helium gas channels 114. As shown in FIG. 7 , 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 protruding portion 1121 .

Embodiment 2

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 second dielectric layer 211 is embedded in 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 formed by the second dielectric layer 212 and the base 210 to prevent the dopants in the first dielectric layer 211 from being eroded by plasma and generating contaminants.

Embodiment 3

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

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

In the present invention, the second dielectric layer 112 of high resistivity undoped ceramic material completely covers the first dielectric layer 111 of low resistivity doped ceramic material, and is provided in the first dielectric layer 111 The electrode 113 realizes "raising" the position of the electrode 113, and the second dielectric layer 112 can generate electrostatic attraction force to the wafer W without disposing the electrode 113 in the second dielectric layer 112. Since the second dielectric layer 112 does not include the electrode 113, the second dielectric layer 112 is thinner than the high-resistivity material dielectric layer used in the conventional technology, and the second dielectric layer 112 can be made without applying an excessively high DC voltage. The two dielectric layers 112 generate sufficient adsorption force and effectively prevent helium gas ignition on the back side of the wafer W. Furthermore, since the electrostatic chuck of the present invention has a smaller leakage current than the electrostatic chuck using a dielectric layer made of high resistivity material in the conventional technology, it is easier to desorb the wafer W.

Therefore, the electrostatic chuck of the present invention has the advantages of easy desorption and no need to apply high DC voltage, 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 are only specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any person with ordinary knowledge in the technical field can easily think of various etc. within the technical scope disclosed in the present invention. Effective modifications or substitutions shall be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the claimed protection scope of the patent application.

100: Vacuum reaction chamber 101: Reaction chamber wall 102:Open your mouth 110,210,310: base 111,211: first dielectric layer 112,311: Second dielectric layer 1121:Protruding 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 explain the technical solution of the present invention more clearly, the drawings required for the description will be briefly introduced below. Obviously, the drawings in the following description are an embodiment of the present invention, and are generally used in the technical field. For those who know it, other drawings can be obtained based on these drawings without making any progressive changes: Figure 1A is a schematic diagram of a plasma reaction device used in the electrostatic chuck of the present invention in Embodiment 1; 1B and 2 are schematic structural diagrams of the electrostatic chuck of the present invention in Embodiment 1; Figure 3 is a schematic diagram of the working principle of an electrostatic chuck using only a dielectric layer of high resistivity material; Figure 4 is a schematic diagram of the working principle of an electrostatic chuck using only a dielectric layer of low resistivity material; Figure 5 is a schematic structural diagram of the electrostatic chuck of the present invention in Embodiment 2; Figure 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 thermally conductive gas through a helium gas channel to the gap between the wafer and the second dielectric layer.

110:Pedestal

111: First dielectric layer

112: Second dielectric layer

113:Electrode

W:wafer

Claims (14)

An electrostatic chuck, which includes: a base; a first dielectric layer disposed on the base; the first dielectric layer is a doped ceramic material with a first resistivity, and the third A dielectric layer is provided with an electrode that generates electrostatic force; and a second dielectric layer is disposed on the first dielectric layer and covers the first dielectric layer; the second dielectric layer has the An undoped ceramic material with a second resistivity; the second resistivity is greater than the first resistivity; and the thickness of the second dielectric layer is 0.01mm~0.5mm. 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 of 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 according to 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 3um. The electrostatic chuck according to claim 1, wherein an adhesive is provided between the first dielectric layer and the second dielectric layer for fixedly connecting the first dielectric layer and the second dielectric layer. Connection layer. The electrostatic chuck according to claim 1, wherein the thickness of the first dielectric layer is 0.2~2mm. The electrostatic chuck according to 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 of 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 according to claim 1, wherein the first dielectric layer is embedded and disposed 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 A dielectric layer is disposed on the base and completely covers the first dielectric layer. The electrostatic chuck according to claim 1, wherein the outer wall of the base is provided with a coating that is resistant to plasma corrosion. The electrostatic chuck of claim 6, wherein a plurality of cooling ducts are provided in the base, and the cooling ducts include a helium gas channel through which helium gas is passed to the wafer and the second dielectric There is a gap between the layers, and the helium channel avoids the bulge. A plasma reaction device includes a plasma reaction chamber, wherein an electrostatic chuck as described in any one of claims 1 to 13 is provided at the bottom of the plasma reaction chamber, and the wafer to be processed is adsorbed by the electrostatic chuck.

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