Electrostatic chuck and plasma reactor
By incorporating ceramic dielectric layers with different resistivities and adding protrusions into the electrostatic chuck, the problems of insufficient adsorption force, difficulty in desorption, and short lifespan of the electrostatic chuck in semiconductor manufacturing are solved, achieving efficient and safe wafer processing.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- ADVANCED MICRO FAB EQUIP INC CHINA
- Filing Date
- 2021-03-30
- Publication Date
- 2026-06-12
AI Technical Summary
Existing electrostatic chucks suffer from problems such as insufficient adsorption force, difficulty in desorption, short lifespan, susceptibility to corrosion, and helium arcing during semiconductor manufacturing, which affect wafer processing accuracy and yield.
By combining doped and undoped ceramic dielectric layers with different resistivities, adsorption forces are generated through electrostatic induction, and protrusions and cooling channels are set between the dielectric layers to achieve uniform adsorption and efficient desorption.
It improves the yield and production efficiency of wafer processing, extends the service life of electrostatic chucks, reduces maintenance costs, prevents helium arcing, and ensures uniformity of temperature and adsorption force.
Smart Images
Figure CN115148653B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of semiconductor technology, and in particular to an electrostatic chuck and plasma reaction device. Background Technology
[0002] In the manufacturing process of semiconductor devices, electrostatic chucks (ESCs) are generally used to generate electrostatic attraction in order to perform deposition, etching and other processes on wafers, so as to support and fix the wafers to be processed during the process.
[0003] An electrostatic chuck consists of a base and a dielectric layer on top of the base. Based on the type of dielectric layer, electrostatic chucks are mainly divided into two types: CB (Coulomb) type and JR (Johnsen-Rahbek) type. CB type electrostatic chucks (abbreviated as CB ESC) and JR type electrostatic chucks (abbreviated as JR ESC) are based on the principle of electrostatic adsorption. By applying an external DC voltage to the electrodes inside the CB ESC or JR ESC, an electrostatic adsorption force is generated to fix the wafer.
[0004] CB ESCs have weak electrostatic attraction and require a high DC voltage to be applied to their electrodes; however, if the applied DC voltage is too high, it can easily cause helium arcing between the wafer and the CB ESC.
[0005] JR ESCs have high leakage current, and even after the external DC voltage is stopped, a significant amount of residual charge remains on the J-RESC surface, making wafer desorption difficult. Furthermore, the rough surface of JR ESCs is easily corroded, leading to increased particulate matter, premature aging, and a deterioration in surface roughness, resulting in a shorter lifespan. Additionally, it can cause uneven temperature distribution on wafers placed on JR ESCs, affecting wafer processing accuracy. Summary of the Invention
[0006] The purpose of this invention is to provide an electrostatic chuck and a plasma reaction device. By combining dielectric layers with different resistivities, the lifespan of the electrostatic chuck can be improved, and a high DC voltage can be applied without the need to prevent helium arcing on the back of the wafer. At the same time, the adsorption force is strong, the adsorption force is evenly distributed, and the wafer is easily desorbed.
[0007] To achieve the above objectives, the present invention provides an electrostatic chuck, comprising:
[0008] Base
[0009] A first dielectric layer is disposed on the base; the first dielectric layer is a doped ceramic material with a first resistivity, and electrodes for generating electrostatic force are provided in the first dielectric layer.
[0010] A second dielectric layer is disposed on the first dielectric layer and covers 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 resistivity.
[0011] Preferably, the first dielectric layer is doped Al2O3, and the dopant includes one or more of Si, C, Mg, MgO, and TiO2.
[0012] Preferably, the second dielectric layer is undoped Al2O3.
[0013] Preferably, the resistivity of the first dielectric layer is 10. 10 ~10 12 Ω.cm.
[0014] Preferably, the resistivity of the second dielectric layer is greater than 10. 14 Ω.cm.
[0015] 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 μm.
[0016] Preferably, an adhesive layer for fixing the first and second dielectric layers is provided between the first and second dielectric layers.
[0017] Preferably, the thickness of the first dielectric layer is 0.2 to 2 mm.
[0018] Preferably, the thickness of the second dielectric layer is 0.01 to 0.5 mm.
[0019] Preferably, the first dielectric layer has a surface roughness of 0.6 to 0.8 μm; and the second dielectric layer has a surface roughness of 0.1 to 0.2 μm.
[0020] 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 wall of the first dielectric layer.
[0021] 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 disposed on the base and completely covers the first dielectric layer.
[0022] Preferably, the outer wall of the base is provided with a plasma corrosion resistant coating.
[0023] Preferably, the base is provided with a plurality of cooling pipes, the cooling pipes including helium channels, through which helium gas is passed to the gap between the wafer and the second dielectric layer, and the helium channels avoid the protrusions.
[0024] The present invention also provides a plasma reaction device, including a plasma reaction chamber, wherein an electrostatic chuck as described in the present invention is provided at the bottom of the plasma reaction chamber, and the wafer to be processed is adsorbed by the electrostatic chuck.
[0025] Compared with the prior art, the beneficial effects of the present invention are as follows:
[0026] 1) The electrostatic chuck of the present invention has strong adsorption force and uniform adsorption force distribution, and easily desorbs wafers, thereby improving the production efficiency and wafer yield of wafer processing.
[0027] 2) Because an undoped second dielectric layer is covered on the first dielectric layer, the generation of particulate contaminants is reduced, resulting in a more uniform adsorption force and temperature distribution of the electrostatic chuck. This not only further improves the yield of wafer processing, but also increases the service life of the electrostatic chuck and reduces the maintenance and manufacturing costs of the electrostatic chuck.
[0028] 3) The present invention uses a doped and low resistivity first dielectric layer. The electrode position of the electrostatic chuck is "raised" by the free-moving electrons in the first dielectric layer. Since no electrodes are required in the second dielectric layer, the second dielectric layer can have a small 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.
[0029] 4) The electrostatic chuck of the present invention only requires a very small DC voltage to operate, thus effectively preventing helium arcing on the back side of the wafer, achieving safe production, and further improving the yield of wafer processing. Attached Figure Description
[0030] To more clearly illustrate the technical solution of the present invention, the accompanying drawings used in the description will be briefly introduced below. Obviously, the drawings in the following description are one embodiment of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort:
[0031] Figure 1 This is a schematic diagram of the plasma reaction device used in the electrostatic chuck of the present invention in Embodiment 1;
[0032] Figure 1A , Figure 2 This is a schematic diagram of the electrostatic chuck structure of the present invention in Embodiment 1;
[0033] Figure 3A schematic diagram illustrating the working principle of an electrostatic chuck that uses only a high resistivity dielectric layer.
[0034] Figure 4 A schematic diagram illustrating the working principle of an electrostatic chuck that uses only a low-resistivity dielectric layer.
[0035] Figure 5 This is a schematic diagram of the electrostatic chuck structure of the present invention in Embodiment 2;
[0036] Figure 6 This is a schematic diagram of the electrostatic chuck structure of the present invention in Embodiment 3;
[0037] Figure 7 This is a schematic diagram showing the passage of thermally conductive gas through a helium channel to the gap between the wafer and the second dielectric layer. Detailed Implementation
[0038] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0039] Example 1
[0040] Figure 1 This diagram shows a schematic of the plasma reaction apparatus used in the electrostatic chuck of the present invention. Figure 1 The plasma reaction device in this invention is a capacitively coupled plasma (CCP) reaction device, and the electrostatic chuck of this invention is also applicable to inductively coupled plasma (ICP) reaction devices. Figure 1The capacitively coupled plasma reactor (CCP) is a device that generates plasma within a reaction chamber via capacitive coupling using a radio frequency power supply applied to a base, and is used for etching. It includes a vacuum reaction chamber 100, which has a generally cylindrical sidewall 101 made of metallic material. An opening 102 is provided on the sidewall for accommodating the entry and exit of a wafer. A gas spray head 120 and a base 110 are disposed within the reaction chamber, opposite to the gas spray head. The gas spray head 120 is connected to a gas supply device 125 for supplying reactive gas to the vacuum reaction chamber and also serves as the upper electrode of the vacuum reaction chamber. The base 110 serves as the lower electrode of the vacuum reaction chamber, and a reaction region is formed between the upper and lower electrodes. At least one radio frequency (RF) power supply 150 is applied to one of the upper or lower electrodes through a matching network 152, generating an RF electric field between the upper and lower electrodes to dissociate the reactive gas into plasma. The plasma contains a large number of active particles such as electrons, ions, excited-state atoms, molecules, and free radicals. These active particles can undergo various physical and chemical reactions with the surface of the wafer to be processed, altering the morphology of the wafer surface, thus completing the etching process. An exhaust pump 140 is also installed below the vacuum reaction chamber 100 to discharge reaction byproducts from the reaction chamber and maintain the vacuum environment of the reaction chamber.
[0041] An electrostatic chuck uses electrostatic adsorption to hold a wafer W placed on it. Its advantages include uniform adsorption across the wafer surface, preventing warping or deformation of the wafer W, causing no damage, and maintaining a stable adsorption force to ensure the wafer W's processing precision. For example... Figure 1 , Figure 1A , Figure 2 As shown, 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.
[0042] like Figure 1 , Figure 1A , Figure 2 As shown, the first dielectric layer 111 is disposed on the base 110 (in the example, the bottom of the first dielectric layer is fixed to the top of the base by adhesive bonding), and it is a doped ceramic material with a first resistivity. In an embodiment of the present invention, the first dielectric layer 111 is doped Al2O3, and the dopant includes one or more of Si, C, Mg, MgO, and TiO2. The first dielectric layer 111 can be processed by powder spraying, plasma CVD (chemical vapor deposition), etc., or it can be machined from ceramic powder after casting and sintering. The resistivity of the first dielectric layer 111 is 10⁻⁶. 10 ~10 12 Ω.cm. In a preferred embodiment of the present invention, the resistivity of the first dielectric layer 111 is 10 Ω·cm. 11Ω.cm. In this embodiment, as Figure 1A , Figure 2 As shown, the thickness of the first dielectric layer 111 is d1 = 0.2–2 mm. The surface roughness of the first dielectric layer 111 is 0.6–0.8 μm.
[0043] like Figure 1 , Figure 1A , Figure 2 As shown, the electrode 113 is disposed within the first dielectric layer 111 to generate electrostatic force, thereby achieving adsorption and fixation of the wafer W to be processed during the process.
[0044] like Figure 1 , Figure 1A , Figure 2 As shown, the second dielectric layer 112 is disposed on the first dielectric layer 111, and the periphery of the second dielectric layer 112 extends downward (e.g., Figure 2 (As shown by the dashed circle in the middle) and completely covers the outer wall of the first dielectric layer 111. Therefore, the first dielectric layer 111 is disposed within the space formed by the base 110 and the second dielectric layer 112.
[0045] Since undoped Al2O3 is resistant to plasma erosion, completely covering the first dielectric layer 111 with the second dielectric layer 112 effectively prevents dopants in the first dielectric layer 111 from being eroded by the plasma in the reaction chamber, thus preventing particulate contaminants from adhering to the wafer W. Because no particulate contaminants are generated, the electrostatic chuck of this invention can ensure uniform temperature of the wafer W and uniform distribution of adsorption force on the wafer W.
[0046] An adhesive layer (not shown in the figure) is also provided between the first and second dielectric layers 112, through which the first dielectric layer 111 and the second dielectric layer 112 are fixedly connected.
[0047] 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 In a preferred embodiment of the present invention, the resistivity of the second dielectric layer is 10 Ω·cm. 17 Ω.cm. Because the resistivity of the second dielectric layer 112 is greater than that of the first dielectric layer 111, the second dielectric layer 112 is also said to have high resistivity, and the first dielectric layer has low resistivity. In embodiments of the present invention, the second dielectric layer 112 is undoped Al2O3, which can be formed by machining. Figure 1A , Figure 2 As shown, in this embodiment, the thickness of the second dielectric layer 112 is d2 = 0.1–0.5 mm. The surface roughness of the second dielectric layer 112 is 0.1–0.2 μm.
[0048] The electrostatic chuck of the present invention can generate sufficient adsorption force on the wafer W by the second dielectric layer 112 without applying an excessively high DC voltage to the electrode 113, and effectively prevent helium arcing on the back side of the wafer. Furthermore, the electrostatic chuck of the present invention has low leakage current, thus making it very easy to desorb the wafer W.
[0049] The following is a description of the principles of this invention:
[0050] The principle of electrostatic adsorption is that when a charged object approaches another uncharged object, due to electrostatic induction, the uncharged object will accumulate charges of opposite polarity to the charged object on the side closest to the charged object (while the same number of charges of the same polarity as the charged object will be generated on the other side). Due to the mutual attraction between opposite charges on the two contacting surfaces, the two objects will have an attractive force, which is the "electrostatic adsorption" effect.
[0051] A typical electrostatic chuck usually consists of: a base made of thermally conductive material, a dielectric layer disposed on the base, and electrodes disposed within the dielectric layer. The properties of the dielectric layer have a significant impact on the electrostatic chuck's adsorption force, desorption capacity, and lifespan.
[0052] like Figure 3 The electrostatic chuck in this design uses a high-resistivity dielectric layer 112′ (resistivity on the order of 10). 9 Ohm), an electrode 113' is provided within the dielectric layer 112'. Figure 3 The base of the electrostatic chuck is not shown. (e.g.) Figure 3 As shown, the dielectric layer 112′ is roughly disk-shaped, with a diameter slightly smaller than the diameter of the wafer W adsorbed on it, to ensure that the wafer completely covers the dielectric layer 112′ and prevent plasma from damaging it. When electrostatic attraction is generated, the wafer W acts as the upper electrode, and the electrode 113′ acts as the lower electrode. Because the dielectric layer 112′ has a high resistivity, it is absolutely insulating, containing very few freely moving electrons and only generating polarization charges. The external DC voltage ( Figure 3 A positive voltage is applied to the lower electrode, thus creating a potential difference between the upper electrode (wafer W) and the lower electrode. This potential difference allows the wafer W to be attracted to the electrostatic chuck.
[0053] The adsorption force F of this type of electrostatic chuck chuck1 The calculation formula is as follows:
[0054]
[0055] Where ε is the relative permittivity of the insulating dielectric layer, ε0 is the vacuum permittivity, 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.
[0056] According to formula (1), F chuck1 It is inversely proportional to the square of d. Because electrodes 113' need to be placed inside dielectric layer 112', and the mechanical strength and flatness of dielectric layer 112' need to be guaranteed, the processing of dielectric layer 112' is difficult, and dielectric layer 112' cannot be too thin (typically, this insulating dielectric layer 112' is set to 2mm). The greater the thickness of dielectric layer 112', the greater the electrostatic attraction force F. chuck1 The smaller the value, the higher the DC voltage (around 2000 volts) required to provide sufficient adhesion to the wafer W.
[0057] In semiconductor processing, heat dissipation of wafer W is crucial. If the surface temperature of wafer W cannot be uniform, the processing uniformity cannot be guaranteed, and the processing accuracy will be greatly affected. Typically, improving the heat dissipation of the back side of the wafer allows localized high temperatures to dissipate immediately, thus ensuring a uniform surface temperature. This method relies on electrostatic chucks to conduct heat through the wafer W, and the heat dissipation effect depends primarily on the material of the electrostatic chucks.
[0058] Another method for heat dissipation of wafer W is to increase gas convection on the wafer surface, using gas convection heat dissipation to uniformly heat the wafer surface. The substrate 110 includes a first channel for routing a heat-conducting gas (such as helium) to the substrate and dielectric layer 112'. Figure 3 (Not shown in the image). The dielectric layer 112' is also provided with a plurality of second channels that connect to the first channel. Figure 3 (Not shown in the image), used to transport the heat-conducting gas between the upper surface of the dielectric layer and the bottom surface of the wafer W, promoting heat transfer between the wafer W and the dielectric layer 112′. Figure 1 , Figure 1A As shown, the base is also equipped with a coolant channel for controlling the temperature of the base 110.
[0059] Since the dielectric layer 112′ needs to be approximately 2 mm thick, the electrodes 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 may cause helium arcing on the back of the wafer.
[0060] like Figure 4 The electrostatic chuck in the middle uses a low resistivity dielectric layer 112″ (the resistivity of the dielectric layer 112″ is on the order of 10). 6 Ohm). Figure 4 The base of the electrostatic chuck is not shown. Figure 4An electrode 113' is disposed inside the dielectric layer 112'. The dielectric layer 112' is not an ideal insulating medium, meaning that there are many freely moving electrons within the dielectric layer 112', resulting in a finite resistance in the dielectric layer 112'. When a voltage is applied to the electrode 113' within the dielectric layer 112'... Figure 4 When a positive voltage is applied (in the middle), the mobile particles within the dielectric layer 112″ are acted upon by the electrode 113″, causing electrons to migrate and accumulate on the lower surface of the dielectric layer 112″, while positively charged particles accumulate on the upper surface of the dielectric layer 112″. That is... Figure 4 The electrostatic chuck shown conducts positive charges to the upper surface of the electrostatic chuck through leakage current.
[0061] like Figure 4 As shown, since the upper surface of dielectric layer 112″ is not an ideal plane, its roughness cannot be ignored, forming several "peaks" and "valleys" on the upper surface of dielectric layer 112″. Due to the "sharp effect," positively charged particles accumulate at the "peaks." A micro electric field is formed between the "peaks" and the negative electrons on the back side of the wafer. The electric field force generated by countless micro electric fields constitutes the adsorption force of the electrostatic chuck. The electric field strength of this micro electric field increases with the increase of the DC voltage applied to electrode 113″.
[0062] The electric force F of a micro electric field chuck2 The calculation formula is as follows:
[0063]
[0064] Where ε0 is the vacuum permittivity, V gap d represents the potential difference between the "peak" and the back surface of the wafer. gap Let S be the distance between the "peak" of the micro electric field and the back surface of the wafer. Based on the actual area S of the wafer W, the result can be obtained by integrating equation (2). Figure 4 The adsorption force F of the electrostatic chuck chuck3 :
[0065]
[0066] Because of d gap Typically only 1–2 μm in diameter, therefore, a small DC voltage (700–1000 V) is required to generate sufficient adsorption force on electrode 113″. Figure 4 The electrostatic chuck shown has a much stronger adsorption force than... Figure 3 The electrostatic chuck shown has an adsorption force that is commonly used in the semiconductor industry, such as... Figure 4 The electrostatic chuck shown.
[0067] But at the same time Figure 4 Electrostatic chucks also have significant drawbacks:
[0068] 1) After the DC voltage is stopped being applied to the electrode 113″ of the electrostatic chuck, the charge on the “peak” is still difficult to release, which leads to the problem of difficulty in desorbing the wafer W.
[0069] 2) When too much charge accumulates on the "peak", it will discharge onto wafer W, causing wafer W to be damaged;
[0070] 3) The adsorption force of this electrostatic chuck also changes significantly with temperature, making the adsorption force unstable.
[0071] 4) Because the dielectric layer 113″ of the electrostatic chuck is doped, the dopants are easily eroded by the plasma in the reaction chamber. During use, the electrostatic chuck has a short lifespan, is prone to particulate contamination, and is prone to uneven temperature of the wafer W and uneven distribution of adsorption force, among other problems.
[0072] In this invention, the aforementioned problems and shortcomings are overcome by employing two dielectric layers with different resistivities. For example... Figure 2 As shown, in this invention, because the resistivity of the first dielectric layer 111 is low, there are many freely moving electrons inside it. Figure 2 In this process, a positive voltage is applied to the electrode 113 within the first dielectric layer. When a positive voltage is applied to the electrode 113 within the first dielectric layer, the aforementioned freely moving electrons accumulate on the lower surface of the first dielectric layer 111. Positively charged particles accumulate on the upper surface of the first dielectric layer. The positively charged particles on the upper surface of the first dielectric layer generate electrostatic induction with the lower surface of the second dielectric layer, thus generating a negative polarized charge on the lower surface of the second dielectric layer and a positive polarized charge on the upper surface of the second dielectric layer. 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, the second dielectric layer 112 will attract the wafer W. That is, it is equivalent to "raising" the position of the electrode 113 into the second dielectric layer, but in reality, it is not necessary to set the electrode 113 in the second dielectric layer, so that the second dielectric layer 112 can attract the wafer W through its polarized charge. Since it is not necessary to set the electrode 113 inside the second dielectric layer, the second dielectric layer 112 of the present invention can be compared with... Figure 3 The dielectric layer 112′ of the electrostatic chuck shown has a smaller thickness, even as small as 0.01 mm. According to formula (1), due to the reduced thickness of the second dielectric layer 112, the electrostatic chuck of the present invention requires only a smaller DC voltage (below 2000 V) to provide sufficient adsorption force for the wafer W. When the applied DC voltage is reduced, the risk of helium arcing on the back of the wafer W is naturally eliminated.
[0073] The leakage current of the electrostatic chuck of this 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 and the second dielectric layer 112, and... Figure 4 Compared to the electrostatic chucks shown, the electrostatic chuck of the present invention can significantly reduce leakage current and is easier to desorb from wafer W.
[0074] In other embodiments, a negative voltage can be applied to the electrode 113 within the first dielectric layer. When a negative voltage is applied, electrons within the first dielectric layer migrate and accumulate on the upper surface of the first dielectric layer due to the action of the electrode 113, while positively charged particles accumulate on the lower surface of the first dielectric layer. That is, negative charges are conducted to the upper surface of the first dielectric layer through leakage current. Simultaneously, the polarization charge on the lower surface of the second dielectric layer is positive, and the polarization charge on the upper surface of the second dielectric layer is negative. Through electrostatic induction, positive charges accumulate on the back side of the wafer. This creates a potential difference between the wafer W and the second dielectric layer 112, which is used to attract the wafer W.
[0075] like Figure 7 As shown, the surface of the second dielectric layer 112 that contacts the wafer W has multiple uniformly or non-uniformly distributed protrusions 1121; the height of the protrusions 1121 ranges from 2 to 3 μm. Compared to contacting the wafer W completely through a plane, the second dielectric layer 112 reduces the contact area with the wafer W through multiple protrusions 1121, which facilitates rapid desorption of the wafer W. Simultaneously, the protrusions 1121 create a gap between the wafer W and the second dielectric layer 112. When a heat-conducting gas (such as helium) is injected into this gap, heat from the wafer W can be carried away through heat transfer between the gas and the wafer W.
[0076] The base 110 of the present invention is also provided with a plurality of cooling pipes, wherein the cooling pipes include helium gas channels 114. For example... Figure 7 As shown, helium gas is introduced into 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 protrusion 1121.
[0077] Example 2
[0078] like Figure 5 As shown, 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 is flush with the top surface of the base; the second dielectric layer 212 is disposed on the base 210 and completely covers the first dielectric layer 211. The first dielectric layer 211 is located within the space formed by the second dielectric layer 212 and the base 210, preventing dopants in the first dielectric layer 211 from being eroded by plasma and generating contaminants.
[0079] Example 3
[0080] like Figure 6 As shown, in this embodiment, the outer wall of the base 310 is provided with a plasma-resistant coating 314. This coating 314 protects the base from plasma erosion within the reaction chamber and further reduces the generation of particulate contaminants. This is beneficial for improving the yield of wafer W processing.
[0081] The present invention also provides a plasma reaction device, including a plasma reaction chamber, wherein an electrostatic chuck as described in the present invention is provided at the bottom of the plasma reaction chamber, and the wafer W to be processed is adsorbed by the electrostatic chuck.
[0082] In this invention, a second dielectric layer 112 of high-resistivity undoped ceramic material completely covers a first dielectric layer 111 of low-resistivity doped ceramic material. Electrodes 113 are disposed within the first dielectric layer 111, effectively "raising" the position of the electrodes 113. This eliminates the need for electrodes 113 within the second dielectric layer 112 to generate electrostatic attraction to the wafer W. Since the second dielectric layer 112 does not contain electrodes 113, it is thinner than the high-resistivity dielectric layers used in the prior art. Sufficient attraction is achieved without applying excessively high DC voltage, effectively preventing helium arcing on the back of the wafer. Furthermore, the electrostatic chuck of this invention has lower leakage current compared to prior art electrostatic chucks using high-resistivity dielectric layers, making it easier to desorb the wafer W.
[0083] Therefore, the electrostatic chuck of the present invention has the advantages of easy desorption, no need to apply high DC voltage, and is not easily corroded by plasma, has a longer service life, and can effectively prevent helium arcing, which greatly improves production efficiency and increases the success rate of wafer processing.
[0084] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in the present invention, and these modifications or substitutions should all be covered within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.
Claims
1. An electrostatic chuck, characterized in that, Include: The base serves as the lower electrode of the vacuum reaction chamber; A first dielectric layer is disposed on the base; the first dielectric layer is a doped ceramic material with a first resistivity, and electrodes for generating electrostatic force are provided within the first dielectric layer; the first resistivity is 10. 10 ~10 12 Ω.cm; A second dielectric layer is disposed on and covers the first dielectric layer; the second dielectric layer is an undoped ceramic material having a second resistivity; The second resistivity is greater than the first resistivity; the resistivity of the second dielectric layer is greater than 10. 14 Ω.cm; The thickness of the second dielectric layer is 0.01 to 0.5 mm, and the wafer is fixed by the adsorption force generated by the second dielectric layer; The periphery of the second dielectric layer extends downward and completely covers the outer wall of the first dielectric layer; the surface of the second dielectric layer in contact with the wafer is provided with a plurality of uniformly or non-uniformly distributed protrusions.
2. The electrostatic chuck as described in claim 1, characterized in that, The first dielectric layer is doped. Its dopants contain , Any one or more of Mg, MgO, and TiO2.
3. The electrostatic chuck as described in claim 1, characterized in that, The second dielectric layer is undoped. .
4. The electrostatic chuck as described in claim 1, characterized in that, The height of the protrusion ranges from 2 to 3 μm.
5. The electrostatic chuck as described in claim 1, characterized in that, An adhesive layer for fixing the first and second dielectric layers is also provided between the first and second dielectric layers.
6. The electrostatic chuck as described in claim 1, characterized in that, The thickness of the first dielectric layer is 0.2–2 mm.
7. The electrostatic chuck as described in claim 1, characterized in that, The first dielectric layer has a surface roughness of 0.6–0.8 μm; the second dielectric layer has a surface roughness of 0.1–0.2 μm.
8. The electrostatic chuck as described in claim 1, characterized in that, The bottom of the first dielectric layer is bonded to the top of the base.
9. The electrostatic chuck as described in claim 1, characterized in that, 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 disposed on the base and completely covers the first dielectric layer.
10. The electrostatic chuck as described in claim 1, characterized in that, The outer wall of the base is coated with a plasma corrosion resistant film.
11. The electrostatic chuck as described in claim 4, characterized in that, The base is provided with several cooling pipes, each containing a helium gas channel through which helium gas is passed to the gap between the wafer and the second dielectric layer, and the helium gas channel avoids the protrusion.
12. A plasma reaction apparatus, comprising a plasma reaction chamber, characterized in that, The bottom of the plasma reaction chamber is provided with an electrostatic chuck as described in any one of claims 1 to 11, through which the wafer to be processed is adsorbed.