A kind of electrostatic chuck that forms subregion with different materials
Technical field
The utility model relates to a kind of electrostatic chuck that is used for fixing wafer, particularly a kind of different electrostatic chuck of material that is provided with subregion and subregion.
Background technology
In the manufacture process of semiconductor device, on wafer, deposit, during PROCESS FOR TREATMENT such as etching, the electrostatic force that generally produces through electrostatic chuck (Electrostatic chuck is called for short ESC) supports wafer during handling and is fixing.
Comprise reaction chamber in the plasma processing apparatus, the top in the chamber is provided with spray head or similar device, and it is provided with as top electrode ground connection; Be distributed with a plurality of air vent holes on the spray head, the reacting gas of introducing is delivered in the reaction chamber.
Corresponding with spray head, said electrostatic chuck is set on the bottom base in reaction chamber, electrostatic chuck comprises dielectric layer; Be embedded with DC electrode in the dielectric layer, be communicated with the back with DC power supply and produce electrostatic force, come the wafer of placing on the sticking dielectric layer.Going back distributed and arranged in the dielectric layer has the gas passage of carrying coolants such as helium, and those passages are communicated to the raceway groove position on electrostatic chuck surface at last.
Be provided with radio frequency electrode in the said pedestal, it cooperates top electrode in reaction chamber, to form rf electric field with after radio-frequency power supply is communicated with, in order to form the plasma that wafer is handled.Also offer some medium channels in the said pedestal, heat or cool off the temperature of said electrostatic chuck and then the temperature of control wafer by the fluid of flowing through in the medium channel.
Yet, in the existing plasma processing apparatus, tend to receive the uneven influence of reaction chamber reaction gases or plasma distribution, make that the zones of different on the wafer surface has different processing speeds; For zones of different along the wafer radial arrangement; The phenomenon of this inhomogeneous processing is particularly evident; For example can make that the processing speed of wafer central region is very fast, and the processing speed of wafer edge region is slower, can causes the performance of the semiconductor device that zones of different forms on the wafer different like this.
The utility model content
The purpose of the utility model provides a kind of electrostatic chuck that forms subregion with different materials; Use has the material of different conductions or heat conductivility and processes each subregion on the electrostatic chuck; Temperature when adjusting the plasma density that forms on each subregion or carrying out chemical reaction; Change the processing speed of carrying out reactions such as etching on the wafer corresponding region; Offset original reaction chamber reaction gases or the uneven influence of plasma distribution with this, make that finally the speed of the etching processing on the zoness of different such as center wafer and edge can balanced distribution.
The technical scheme of the utility model provides a kind of electrostatic chuck that forms subregion with different materials; It is arranged in the reaction chamber of plasma processing apparatus; Through the received RF energy, the plasma that produces reacting gas is handled wafer in this reaction chamber;
The DC electrode that said electrostatic chuck comprises dielectric layer and wherein buries underground; In plasma treatment procedure, be communicated with the electrostatic force that produces behind the power supply on the said DC electrode, the said wafer that is placed on the electrostatic chuck end face is fixed;
The dielectric layer of said electrostatic chuck comprises several subregions of being processed by different materials, and the position of said each subregion is corresponding with several zones that its top is divided on wafer; The material of processing said each subregion have different conductivity can or heat conductivility, make that the reaction rate of handling through plasma on the corresponding region of said wafer is different;
Under the situation of ceteris paribus; The conductivity of said electrostatic chuck subregion is good more; Energy RF-coupled on this subregion is big more, and the plasma density that then above this subregion, forms is high more, and the reaction rate of said plasma when handle the corresponding region on the wafer is fast more;
Under the situation of ceteris paribus, the thermal conductivity of said electrostatic chuck subregion is good more, and this subregion is high more through the temperature that receives heat and promote, and the reaction rate of then utilizing plasma that this subregion top forms that corresponding region on the wafer is handled is fast more.
The dielectric layer in the vertical direction of said electrostatic chuck is formed by several layer stack, and the different some subregions of said material are set in the layering at least therein.
In a preferred embodiment, some subregions that said material is different are arranged in the said electrostatic chuck in the dielectric layer layering near its end face.
The dielectric layer of said electrostatic chuck comprises several subregions that concentric is provided with, and said several subregions are radially arranged to the edge from the center of this electrostatic chuck successively; Several zones of from the center to the edge, radially dividing on said each subregion and the said wafer are corresponding.
Among a kind of embodiment, some subregions of said concentric, its conductivity increases progressively to edge direction from the center of electrostatic chuck, that is and, the subregion conductivity at electrostatic chuck center is the poorest, and the subregion conductivity at edge is best.
Among the another kind of embodiment, some subregions of said concentric, its thermal conductivity increases progressively to edge direction from the center of electrostatic chuck, that is and, the subregion thermal conductivity at electrostatic chuck center is the poorest, and the subregion thermal conductivity at edge is best.
The dielectric layer of said electrostatic chuck comprises first subregion and second subregion of concentric, and said first subregion is corresponding with the central area of said wafer, and said second subregion is looped around the periphery of first subregion, and corresponding with the fringe region of said wafer.
Among a kind of embodiment, said first subregion is processed by insulator, and said second subregion is processed by conductor.
Among the another kind of embodiment, said first subregion is processed by the insulator with first dielectric coefficient, and said second subregion is processed by the insulator with second dielectric coefficient; Preferably, make said first dielectric coefficient greater than more than 1.5 times of second dielectric coefficient, even reach more than 2 times.
Compared with prior art; The said electrostatic chuck that forms subregion with different materials of the utility model; Its advantage is: in the utility model, for the processing speed of reactions such as a certain regional etching on the faster wafer, a kind of is on electrostatic chuck, to form the better dielectric layer subregion of conductivity by correspondence position; Strengthen the RF-coupled energy on this subregion, strengthen the concentration of plasma; Another kind is to form the better dielectric layer subregion of thermal conductivity, through promoting the temperature of this subregion, accelerates the chemical reaction rate of corresponding wafer area.Otherwise, adopt conduction or the opposite made subregion of material of heat conductivility, will reduce the processing speed of corresponding wafer area.Therefore; In the said electrostatic chuck of the utility model; In order to offset the influence of originally for example reacting the intracavity gas uneven distribution; Utilized different conduction or the heat conductivilitys of each subregion material on the dielectric layer, can correspondence adjust processing reaction speed, improved the uniformity that wafer surface is handled the wafer respective regions.
Description of drawings
Fig. 1 is the sectional view of a kind of partitioned organization in the said electrostatic chuck of the utility model;
Fig. 2 is the vertical view of partitioned organization in the electrostatic chuck shown in Figure 1;
Fig. 3 is the vertical view of another kind of partitioned organization in the said electrostatic chuck of the utility model;
Fig. 4 is the sectional view that the plasma processing apparatus of electrostatic chuck shown in Figure 3 is set in the utility model.
Embodiment
Embodiment below in conjunction with description of drawings the utility model.
As shown in Figure 4, the described plasma processing apparatus of the utility model comprises a reaction chamber 100, and the top in the chamber is provided with spray head 60, and the bottom in the chamber is provided with electrostatic chuck.Be distributed on the spray head 60 and be provided with a plurality of air vent holes, be used for reacting gas is delivered in the reaction chamber 100, spray head 60 also is provided with as top electrode ground connection.Electrostatic chuck is arranged on the pedestal 40 of reaction chamber 100 bottoms; The radio frequency electrode 41 that is provided with in this pedestal 40 with after the radio-frequency power supply that for example is 13MHz ~ 200MHz is communicated with, is engaged in formation rf electric fields in the reaction chamber 100 with said top electrode, is used for the plasma of reaction of formation gas.Also offer some medium channels 42 in the pedestal 40, heat or cool off said electrostatic chuck by the fluid of flowing through in the medium channel 42, and then the temperature of control wafer 50.
Cooperation is referring to Fig. 1, shown in Figure 4, and described electrostatic chuck comprises dielectric layer 20, and the DC electrode of wherein burying underground 30; Produce electrostatic force after being communicated with power supply on the DC electrode 30, to the fixing sticking of the wafer 50 placed on the electrostatic chuck end face.Said electrostatic chuck is a disc structure, and its area is equal to or slightly less than the area of said wafer 50.
The dielectric layer 20 of electrostatic chuck is divided into some subregions.In one embodiment; Those subregions are processed by the material of different electric conductivities respectively; Thereby on the good more subregion of electric conductivity; RF-coupled energy is just big more, so the plasma density that this subregion top forms is just high more, and the reaction rate on wafer 50 zones corresponding with this subregion is just fast more; Vice versa.
In addition, dielectric layer 20 in the vertical directions are formed by several layer stack, are at least to carry out above-mentioned subregion in the layering therein.For example be divided into four layers in the electrostatic chuck shown in Fig. 1, be from top to down ground floor 21 to the 4th layer 24, DC electrode 30 is arranged in the 3rd layer 23; First, second, the 4th layer can be independently or described subregion is set ordinatedly.If in the layering near the electrostatic chuck end face subregion is being set more, it is just obvious more to the corrective action that plasma density in the reaction chamber 100 distributes.Therefore, preferred, be that the electric conductivity different partition areas is formed on the ground floor 21 that is arranged in dielectric layer 20 tops.
The material of processing subregion can be conductor, semiconductor or insulator, for example is conductor aluminium Al, semiconductor carborundum SiC, insulator quartzy (quartz) or aluminium oxide Al
2O
3, or the like; Also can be the higher organic substance of dielectric constant, like organic polymer.Can be according to the application need of reality, from conductor, semiconductor, insulator or wherein the different insulating material of dielectric coefficient, select any different materials, come correspondence to process each subregion on the electrostatic chuck.Other dielectric layer 20 layerings (for example the second layer 22, the 4th layer 24) that subregion is not set can be to be processed by the thermal conductive ceramic material.
Fig. 1, embodiment shown in Figure 2; Be in the ground floor 21 at electrostatic chuck top; Be disposed radially first subregion 11 and second subregion 12 of concentric, make the subregion 11 of winning corresponding with the central area of wafer 50, second subregion 12 is corresponding with the fringe region of wafer 50.For example use insulator to process first subregion 11; Use conductor to process second subregion 12; The conductivity of then comparing first subregion, 11, the second subregions 12 is better, and RF-coupled energy is bigger; The plasma density of second subregion, 12 tops is higher so; Accordingly will be faster than the processing speed at wafer 50 centers in the processing speed at wafer 50 edges, thus can offset the influence of original reacting gas skewness weighing apparatus on plasma radial, effectively improve wafer 50 surface-treated uniformities.Reach that the materials of first subregion 11 and second subregion, 12 correspondences have the dielectric constant that has a long way to go obvious effects on the different subregions preferably makes electrostatic chuck on material is selected in.Differ to reach more than 1.5 times like both dielectric coefficient and can reach obvious effects, reach more than 2 times even 4 times and can reach better effect.
Perhaps in a further embodiment; According to Fig. 1, partitioned organization shown in Figure 2, use insulator to process first subregion 11 with first coefficient, use insulator to process second subregion 12 with second dielectric coefficient; And; Make second dielectric coefficient less than first dielectric coefficient, then the conductive capability of the 4th subregion 14 is better than the 3rd subregion 13, and so be provided with will be with above-mentioned similar to the adjustment of wafer 50 regional processing speeds for subregion.
Among Fig. 3, the embodiment shown in Figure 4, radially set gradually the 3rd to the 6th subregion 13 ~ 16 of concentric, wherein the 3rd subregion 13 is corresponding with the central area of wafer 50, and the 6th subregion 16 is regional corresponding with wafer 50 edges.For example use insulator to process with first dielectric coefficient at the 3rd subregion 13; The 4th subregion 14 uses the insulator with second dielectric coefficient to process; And, make second dielectric coefficient less than first dielectric coefficient, then the conductive capability of the 4th subregion 14 is better than the 3rd subregion 13; The 5th subregion 15 uses semi-conducting material to process, and the 6th subregion 16 uses conductor material to process; It is thus clear that the electric conductivity of those subregions strengthens gradually; Thereby the plasma density in corresponding wafer 50 central areas is minimum, can be high more and arrive the concentration of wafer 50 edge plasmas more, promptly; Under the situation of ceteris paribus, the etch rate at wafer 50 edges can be faster in reaction chamber 100.
Because plasma etching is physicochemical comprehensive function,, also possibly receive the influence of reaction temperature except relevant with plasma density, gas flow.Therefore, the utility model gives another kind of execution mode, is each subregion that makes on the electrostatic chuck dielectric layer 20, is processed by the material with different heat conductivilitys.In plasma treatment procedure, the subregion that temperature is high more, the speed of chemical reaction is just fast more.In addition on the one hand; The subregion temperature rising of electrostatic chuck can cause resistivity to become big; With the coupling distribution of RF energy indirect relation is arranged also, therefore need carry out Comprehensive Control, thereby zones of different obtains uniform processing speed on wafer 50 temperature of each subregion.
For example; With reference to the partitioned organization of figure 1, electrostatic chuck shown in Figure 2, wherein first subregion 11 and second subregion 12 all are conductors, and the material thermal conductivity of processing second subregion 12 is better than first subregion 11; Behind the heat that pedestal 40 sends below so same the reception; Can make the temperature of second subregion 12 be higher than first subregion 11, the processing reaction speed to wafer 50 edges is just faster on second subregion 12 so, and the processing reaction speed to wafer 50 centers on first subregion 11 is just relatively slow.
Again for example; With reference to the partitioned organization of figure 3, electrostatic chuck shown in Figure 4, make wherein the 3rd subregion 13 to the 6th subregions 16, process by the material correspondence that heat conductivility increases progressively; Promptly; The thermal conductivity of three subregion 13 corresponding with wafer 50 centers is the poorest, and the thermal conductivity of six subregion 16 corresponding with wafer 50 edges is best, and thus obtained adjustment effect to wafer 50 regional processing speeds will be with above-mentioned similar.
The subregion of given electrostatic chuck is set among above-mentioned some embodiment, all is to be used for adjusting in original reaction chamber 100 to fast, the slow problem in edge in the middle of the processing reaction speed of wafer 50.And the division of dielectric layer 20 subregions is not limited to the description in the preceding text; Can comprehensively determine according to concrete needs, for example be dielectric layer 20 vertically on select to be provided with layering quantity and the position (for example being the several layers in ground floor 21, the second layer 22 or the 4th layer 24) of subregion; The perhaps quantity of concentric subregion diametrically, the size of each subregion; Perhaps, subregion is not radially to divide, but divides with other shapes; Or be the material of selecting each subregion; With wafer 50 centers to the corresponding subregion in edge, the performance of its conduction (or heat conduction) must not be the relation that increasing or decreasing changes yet.
In sum; Processing speed for reactions such as a certain regional etchings on the faster wafer 50; A kind of is on electrostatic chuck, to form better dielectric layer 20 subregions of conductivity by correspondence position, strengthens the RF-coupled energy on this subregion, strengthens the concentration of plasma; Another kind is to form better dielectric layer 20 subregions of thermal conductivity, through promoting the temperature of this subregion, accelerates the chemical reaction rate in corresponding wafer 50 zones.Otherwise, adopt conduction or the opposite made subregion of material of heat conductivility, will reduce the processing speed in corresponding wafer 50 zones.Therefore; In the said electrostatic chuck of the utility model; In order to offset the influence of gas uneven distribution in original for example reaction chamber 100; Utilized different conduction or the heat conductivilitys of each subregion material on the dielectric layer 20, can correspondence adjust processing reaction speed, improved wafer 50 surface-treated uniformities wafer 50 respective regions.
Although the content of the utility model has been done detailed introduction through above-mentioned preferred embodiment, will be appreciated that above-mentioned description should not be considered to the restriction to the utility model.After those skilled in the art have read foregoing, for the multiple modification of the utility model with to substitute all will be conspicuous.Therefore, the protection range of the utility model should be limited appended claim.