CN101405607A - High performance miniature RF sensor for use in microelectronics plasma processing tools - Google Patents

Abstract

The present invention provides a high-performance miniature RF sensor that maintains gain, directivity, and isolation in a miniature package. The miniature RF sensor includes stacked current and voltage pickups disposed in a PCB construction, the sensor further including quarter wave transforming filter, triaxial shielding, and skin-effect filtering.

Description

The high-performance micro radio frequency sensor that is used for microelectronics plasma processing tools

The cross reference of related application

With reference to the 60/783rd of application on March 20th, 2006, (undetermined) number U. S. application case that is entitled as " the high-performance micro radio frequency sensor (HIGH PERFORMANCEMINIATURE RF SENSOR FOR USE IN MICROELECTRONICS PLASMA PROCESSINGTOOLS) that is used for microelectronics plasma processing tools " of No. 894 application cases and application on March 19th, 2007, and advocate the right of priority of described application case according to 35 U.S.C. § 119, the full content of above application case all is incorporated herein by reference.

Technical field

Do not have

Background technology

The value of RF sensor (that is to say, measure by high power RF power supply and be fed to the RF electric current of plasma process chamber of microelectronics handling implement and the device of voltage) is good the establishment.Many patents (for example the 6th, 501, No. 285 United States Patent (USP)s) provide sensor and associated signal to handle the design and the application of electronic component.Yet each in these inventions focuses on that all the electromagnetic performance that makes this type systematic reaches maximum.Nearly all RF sensor application all relates to and sensor is retrofitted into not to be original design out in the cold to a great extent with the fact of the existing treatment chamber of holding described device.Because this performance focus is not being carried out under the situation extensive and not desirable modification handling implement and/or RF sensor, existing RF sensor can not be suitable for the great majority application too greatly.

The typical RF sensor of describing as Fig. 1 10 comprises a short coaxial transmission line, through shielding adapter and passive or active filter circuit.RF sensor 10 itself forms coaxial transmission line as follows.At first, sensor shell or box 14 form external conductor and the shielding that is used for adapter.The constant diameter solid hopkinson bar of being made by silver-plated copper or other similar material forms center conductor 18.The dielectric material of being made up of silicon, quartz, silit and/or aluminium oxide and other material 22 is used to keep the predetermined geometric relationship between center conductor 18 and the ground level.Capacitive voltage pickup 26 and inductive current pickup 30 are placed in the dielectric material 22.Plug connects 34 and will go between and pass external conductor from these adapters 26,30 and be fed to corresponding filter circuit 38 and possible extra treatment circuit.Then modified signal is sent to additional unit (not shown) is used for digitizing.

The above-mentioned configuration of typical case RF sensor has significant feature performance benefit.At first by forming the transmission line of length as shown in Figure 1, the RF sensor guarantee regardless of around geometric configuration, adapter all is exposed to uniform electric magnetic field.Therefore, adapter has the constant-gain as the function of electric current and voltage irrelevant with its application.Secondly by forming through the shielding obturator, the RF sensor is guaranteed adapter only to because the field sensitive that electric current on the center conductor and the potential difference (PD) between center conductor and the external conductor cause, and insensitive to external.At last, sensor configuration is adapted to standard RF connector easily, and therefore allows to calibrate on test board.Because Design of Sensor, this calibration keep irrelevant with application.

Standard inductive current pickups and capacitive voltage pickup have the gain that increases with the RF frequency, as curve 42 picture specifications depicted in figure 2.The feature of this explanation has the shortcoming of the dynamic range increase that makes the signal quantity that must pass through RF sensor electronics precise numberization.The simplest is to incorporate into active in sensor or passive filtering (as shown in Figure 1) in order to the known way of proofreading and correct cumulative gain, and then produces than the flat frequency response, describes as the curve 46 according to Fig. 2.In sensor, incorporate filtering into and avoided the complicacy of the length of transmission line between adapter and the wave filter.Because transmission line effect, the mode that the full gain of circuit can be expected is with frequency change.

Filtering circuit also can be used for making the signal from adapter to reach maximum, thereby allows to make the size of adapter to reduce to minimum.Minimum size is important for making the stray impedance that causes crosstalking reduce to minimum.More particularly, any inductance in the capacitive pickup causes influencing the levels of current of voltage signal, and any electric capacity on the inductive pickup causes influencing the voltage levvl of current signal.

At last, such as in the typical RF sensor work, incorporate signal Processing into and have other feature performance benefit.The order of magnitude of the voltage that adapter produced is lower than the level of finding in plasma tool.Signal Processing in the sensor (for example being mixed into intermediate frequency (IF) or even fully digitalization) has significantly reduced the signal ruined risk before it quantizes from adapter.

Standard RF sensor is very easy to use standard RF connector and is coupled to the standard transmission line.Yet this selection also is seldom available if any.In fact, the RF sensor must be retrofitted into the existing RF power path in the plasma process tools.This path is made up of the center conductor with varying dimensions, air dielectric and the non-ground level that clearly defines usually.The RF sensor is installed in these conditions to be required existing power path is made amendment.Except a large amount of effort of needs and parts peculiar, these modifications can cause the electromagnetic property of power path is caused unacceptable change.

An another difficult problem is caused by the physical size of sensor device; Wherein this type of device is defined by the cubical box configuration usually, and the length of each side of wherein said configuration and width all are several inches.In many cases, it is available hardly to be used to the space of installing.This causes one in two unacceptable solutions.The first, need for example to carry out extensive modifications with the form of distance piece, additional conductors and customization counterpart.The installation of these extensive modifications is expensive and consuming time, but also may change tool performance.Perhaps, be not that the RF sensor is installed in its place near plasma chamber of effective monitoring process, but sensor is placed in the position spacious but far away, it is impaired to locate its performance at this.

As a result, the pointed energy of typical R F sensor and compromise workability.Standard design is calibrated easily and guarantee that the reading on the treatment chamber is identical with the reading that obtains on test board.The realization of this performance is significantly to be revised as cost to the electricity of treatment chamber or power path.This modification is expensive and consuming time, and the electromagnetic property of the instrument of can significantly trading off and influence handling property.

Realize that low performance Micro RF sensor is simple relatively.As long as capacitor and inductor are placed near the center conductor, just will produce and the roughly proportional signal of voltage and current.Yet challenge is to keep the high-performance in the Micro RF sensor.In order to obtain high-performance, the practitioner of this technology must successfully keep gain, directivity and the isolation in the microsensor encapsulation.So far, the applicant does not also know to realize the Micro RF sensor package of these targets.

Summary of the invention

Therefore, according to first aspect, provide a kind of be used to measure by high power RF power supply be fed to the RF electric current of plasma process chamber of microelectronics handling implement and the Micro RF sensor of voltage, described subassembly comprises sensor head and comprises the conductor that forms as a side of the box-packed structure that forms shell, described structure comprises current pickup and voltage pickup, and each in the described adapter is relative to each other piled up with described conductor.

In a kind of pattern, electric current and voltage pickup are provided in printed circuit board construction, wherein voltage pickup is formed by grid or the mesh element of being arranged to spaced relationship with respect to described conductor, and wherein said conductor can be the strip conductor of plasma tool.PCB structure, quarter-wave fractal transform wave filter, stacked pickups, three shieldings and kelvin effect filtering, each feature all causes high-performance micro RF sensor.Remodeling and electromagnetic performance target are satisfied in proposed design.

Description of drawings

In order further to understand these targets of application case described herein, will be with reference to the embodiment of reading, in the accompanying drawings below in conjunction with accompanying drawing:

Fig. 1 describes prior art RF sensor;

Fig. 2 comprises the pickup gain variation of filter effect and the known graphic depiction of cumulative RF frequency;

Fig. 3 (a) and 3 (b) describe overlooking and the stage casing plan cross-sectional view according to five box structures of the Micro RF sensor of embodiment respectively;

Fig. 4 (a) and 4 (b) describe respectively through the electric field shielding spare of orientation and the vertical view and the front elevation of voltage pickup;

Fig. 5 (a) and 5 (b) describe vertical view and the stage casing plan cross-sectional view according to the in-built electrical sensor of the RF sensor of embodiment respectively;

Fig. 6 (a) and 6 (b) are the vertical view and the side view of the PCB subassembly partly showed to Fig. 5 of five boxes of depiction 3 respectively;

Fig. 7 describes to comprise the stage casing planimetric map of the RF sensor of skin effect shield and top shield;

Fig. 8 (a) and 8 (b) describe the alternate embodiment of single top shield and balanced top shield respectively;

Fig. 9 describes to be used for the triaxle cable configuration of Micro RF sensor; And

Figure 10 describes to be attached to the variableimpedance Terminal Design of the sensor head of Fig. 9.

Embodiment

This paper is about describing many features through improved Micro RF sensor pack.The design of gained is the high-performance micro RF sensor that satisfies remodeling and electromagnetic performance target.

This paper for the sake of clarity at first states the many targets/requirement of the RF sensor that this paper defines:

1. with the irrelevant constant-gain of application

The voltage and current gain definitions of RF sensor is the output level as the function of the virtual voltage of measurement point and levels of current of each converter.Key request for spendable RF sensor is that the gain of sensor is identical and irrelevant with the application of sensor, and it is insensitive to the variation of RF power path geometric configuration specifically to gain.In this way, the calibration value that obtains on test board can be used for sensor output being converted to engineering unit and haveing nothing to do with application.

2. with the constant-gain of RF frequency-independent

Plasma process tools adopts the RF power supply, and it is being operated to the frequency near the scope of 100MHz from the hundreds of kilohertz.Standard pickups is used faraday's coupling between inductive current pickup and capacitive voltage pickup.The gained gain of these sensors is directly proportional with frequency, as before discussing about Fig. 2.If not calibrated, this effect causes being in low-frequency immeasurablel weak signal and is in the strong signal of high-frequency destructiveness so, shown in curve 46.

3. high directivity

Directivity is meant oriented signal flow, and specifically high power RF voltage flows to the oriented of current pickup to voltage pickup and high power RF electric current.As previously mentioned above, be complete inductive or capacitive without any structure.Therefore, certain part of the signal on the voltage pickup will be owing to the actual current level, and certain part of the signal on the current pickup will be owing to voltage.High directivity means that this is crosstalked reduces to minimum.

4. high the isolation

Isolate the separation that is meant between the signal path.In the RF sensor application, isolate being meant the insensitivity of RF adapter to the field except that field to be measured.RF power path in the plasma process chamber may be comparatively complicated usually, the wherein sometimes doubling of conductor own.In the case, crucial is makes adapter only to the electric condition responsive of measurement point RF power path, and to the electric condition at any other some place insensitive or with its isolation.

5. minimum load

Load on aspect that institute's absorbed power or impedance change and describe the influence of circuit the electric network that comprises it.Under the situation of RF sensor, load is meant owing to adding the RF power path change that sensor produces.Plasma process tools is through accurately calibrating the required output that becomes according to setting (for example, generator power and processing time) to produce.If RF sensor " load " RF power path, so identical setting can not cause identical condition of plasma and handle output changing.Obviously, must make the load effect of RF sensor reduce to minimum.

Referring to Fig. 3 (a) and 3 (b), show the Micro RF sensor pack of making according to the embodiment of the invention 50.Usually, most plasma process tools are used smooth plane RF strap power conductor.Usually, this strap power conductor has the width dimensions of about 0.6 " or 0.75 ".As discussed previously, most of existing RF sensor design are utilized the cube shell.Fig. 3 (a) and (b) shown in subassembly described herein 50 five sided sensor enclosure 56 are provided, it further utilizes 6th wall of the existing flat power conductor bar 60 of plasma process tools as closure member, and then creates and use irrelevant constant electromagnetic environment.According to this embodiment, five face closure spares 56 are wideer than RF conductor 60 on the y direction, shown in Fig. 3 (a) and 4 (a).The result is with the approximate little bar shaped transmission line of mode described below.Five face closure spares 56 serve as the ground level with sidewall, and wherein said is served as the RF conductor herein.Design described herein by analysis and be shown as have constant electric field and magnetic field intensity between conductor and ground level.The more important thing is that field strength is constant, and irrelevant with the bar width, shown in Fig. 3 (b), wherein electric field is described by line 68 and magnetic lines of flux is described by line 74.In fact, one section transmission line with constant EM character is created in above-mentioned design, and not to the big or small of coaxial transmission line or modification requirement.

Referring to Fig. 4 (a) and 4 (b), by with respect in RF conductor 60 stack voltage and the current pickup each and in RF sensor design described herein, realize to close bond space and save.In addition, by making voltage pickup 66 by grid or kind of thread elements, the whole EM field of RF conductor 60 can not captured by voltage pickup, shown in the magnetic lines of flux of representing in the part front elevation of Fig. 4 (b) 74.Then, the current pickup 78 of Fig. 4 (b) can be placed or be positioned on the voltage pickup 66, and still captures magnetic field 74.By making current pickup 78 by the coil at loose interval, whole EM can not captured by current pickup the field yet.Therefore, current pickup 78 also can be placed on voltage pickup 66 belows, but latter's trapping field still wherein.

More particularly, this paper describes the configuration of horizontal screen cloth at capacitive character (voltage) adapter 66, as explanation among Fig. 4 (a) and 4 (b), described adapter 66 permit by means of the voltage pickup through orientation realize directivity and microminiaturization both.According to this design, the voltage pickup that the net of being made by copper or other non-magnetic conductor or other element form is oriented on the direction that is parallel to magnetic lines of flux 74, and wherein the direction of electric current 70 is shown as the direction along x.Thus, capacitive pickup 66 is transparent to magnetic flux effectively.Yet adapter 66 further serves as the shielding part with respect to electric field, shown in Fig. 4 (b).Therefore, discrete component is carried out two functions: serve as voltage pickup; With serve as in order to the shielding part of blocking-up from the electric field of inductive pickup.As described, the current pickup 78 that is loose coil form is stacked on the voltage pickup top, shown in Fig. 4 (b), and then provide the space to save but also improvement direction, because less electric field is transferred to inductor, its effective stray capacitance is reduced, and wherein sensor is the benefit of deriving through improved directivity.

Although for the purpose of creating high-performance micro RF sensor pack may be implemented in a variety of ways piling up of voltage and current adapter, a kind of optimization technique is that whole converter bank component is manufactured on the printed circuit board (PCB) (PCB).

For this reason, this paper describes PCB design.At first, can form inductive (electric current) adapter 80 by two the interior metal layers 84,88 that are engaged with each other by blind via hole that use printed circuit board (PCB) 92 by means of printed circuit board construction referring to Fig. 5 (a) and 5 (b).As discussed previously, current pickup 80 is arranged on the metal level top that is used to define capacitive character (voltage) adapter 96, and described metal level forms grid on the x direction, as shown here.In the above-mentioned layer each is arranged on conductor 60 tops with parallel relation.The advantage that this inductor design has is at utmost to utilize free space to make current gain reach maximum, and allows standard RF connector 108 is installed to centerline near plate 92, as more detailed description hereinafter.Perhaps, replace capacitive pickup layer, plate 92 can comprise in-built electrical capacitive adapter and electric field screen cloth, as described previously.

Briefly, further provide extra structure purpose referring to five sided sensor enclosure 56 shown in Fig. 3 (a) and 3 (b).At first according to this embodiment, the top of box 56 can be incorporated into strain relief member and shielding construction 110, is used for the attached triaxle cable of describing subsequently 140, as Fig. 6 (b) with shown in 9.Another structural requirement relates to five face closure spares 56 is attached to PCB subassembly 92.Shielding and structural object can satisfy by a plurality of through holes around the outer periphery that is arranged on circuit board 92 120.As explanation among Fig. 6 (a) and 6 (b), described a plurality of through holes 120 serve as and are used for the pad that weld strain is eliminated part and shielding construction 110 and extended shielding in each side periphery of circuit board 92.

The degree of depth of penetration by electromagnetic fields conductor becomes according to conduction and frequency.This effect can be utilized by implementing skin effect shield 100 as Fig. 7 is illustrated.In this embodiment, skin effect shield 100 by printed circuit board (PCB) 92 additionally as thin as a wafer metal level form, described metal level is arranged to the most close conductor 60 (that is, below capacitive pickup 96) and is grounding to described a plurality of shielding through hole 120.This shielding part 100 is in order to serve as low-pass filter, so that make the converter frequencies response smooth.More particularly, under low frequency, metal level is much thinner than skin depth, and therefore can cause the decay of electromagnetic field hardly, and can not cause the decay of voltage or current pickup gain.Along with frequency increases, metal level becomes and is similar to skin depth, and is then thick than skin depth, thereby produces the decay that increases with frequency.Net result is to produce effectively and very compact wave filter makes the converter frequencies response smooth effectively through the bottom layer of suitable selection.Fig. 7 further clearly demonstrates the most clearly plate structure, wherein the bottommost layer of PCB forms skin effect shield 100, capacitive pickup 96 next-door neighbours are arranged on kelvin effect screen layer 100 tops, be each that forms in two layers 84,88 of built-in inductive pickup 80 subsequently, wherein shield the periphery of through hole 120 around circuit board 92.The top layer of PCB 92 further comprises a pair of standard RF connector 108 that is attached to it by conventional member, its each be connected to inductive and voltage pickup 80,96 by terminal.

As discussed previously, sensor pack 50 described herein forms sensor head, and it is connected to cable via standard RF connector 108.Connector 108 and cable all can serve as adapter and therefore damage the directivity of sensor pack 50.According to this embodiment, the single top shield 112 of explanation in Fig. 8 (a), this shielding part provided herein is to offset above-mentioned effect.According to this embodiment, on the entire top layer of circuit board 92, use washing, except the plus end of RF connector 108.This metal level ground connection and and then stop that any field is coupled to connector or the cable that is arranged on top barrier layer top.This layer 112 is further with acting on the strain relief member of Fig. 9 and the pad of shielding construction 110.

The alternate embodiment of this design is described in Fig. 8 (b), and relates to balanced top shield 130.Extra earth-shielded the use increase load for the RF power path significantly improved isolation and directivity as cost.By using ground shield, sensor head has more impedance, and therefore serve as to the RF power path than multi-load.Balanced top shield 130 makes to isolate and reaches maximum, makes load effect reduce to minimum simultaneously.In this latter alternative method, do not use five face closure spares, because sensor head does not have external ground.But the top of circuit board 92 is covered by the metallization 134,138 with two separation of area about equally.In the described metallization 1 is connected to the plus end of voltage pickup 66, another metallization 138 ground connection and be connected to the shielding through hole 120.In this configuration, external electrical field will equally be charged in the metallization 134,138 each.Because voltage results from charge difference, so this shielding will be to not influence of capacitive pickup, and therefore voltage gain will be irrelevant with defining of the electric field of outside, RF path, isolation.The method will cause on the RF power path than using the little load of ground shield.Owing to allow the balanced shield stored charge, so it does not serve as the capacitor with respect to the RF power path.

Referring to Fig. 9, with respect to conductor bar 60 and strain relief member and shielding construction 110 displayings five face closure spares 56, wherein the top of closure member comprises opening 57, and described opening 57 allowances are installed to strain relief member and shielding construction the shielding through hole 120 of circuit board 92.In case known concentric cable extends beyond significant electrical length, it also can serve as adapter in the presence of electric field and influence directivity so.Therefore, the triaxle cable 140 that also illustrates among Fig. 9 has been eliminated this problem, also satisfies environmental requirement simultaneously.

Still referring to Fig. 9, comprise structural outer coaxial ground shield according to the triaxle cable 140 of this embodiment, it comprises the outer jacket 142 that covers outer braid 144.This is between coaxial conductor 152 and the outer braid 144 provides dielectric layer 156, wherein triaxle cable enclose a pair of concentric cable 148,150 rather than as under the situation of the typical cable of this type, only enclose individual cable, each concentric cable be arranged on the cable that centers on by coaxial conductor 152 in intracardiac.In this design, the exemplary configurations of coaxial conductor 152 and dielectric materials layer 156 is reversed.That is to say that in typical triaxle cable, dielectric layer is present between inner coaxial conductor and the outer, coaxial conductor.Because RF sensor of the present invention is installed in the high voltage environment, so sensor must be isolated to prevent to be shorted to any high voltage surfaces by enough materials.In order to satisfy this purpose, as shown dielectric layer 156 is arranged on the outside of outer, coaxial conductor.

In addition, can use the minimum circuit in the sensor head to realize making the smooth target of pickup gain frequency response shown in Figure 2 by utilizing transmission line effect.

In order to make the pickup gain response smooth, need the variableimpedance terminal.If capacitive pickup 96 under low frequency with the high impedance termination and under high-frequency with the Low ESR termination, the result will be that constant voltage on the terminal impedance is fallen so, and the constant-gain of saying so haply.For inductive pickup 80, need shunt so that under low frequency, send maximum current and under high-frequency, send minimum current.This is by the variableimpedance terminal is realized with making up to the by-passed resistor of ground connection.Under low frequency, low impedance termination causes most of electric current to flow to terminal, and under high-frequency, high impedance means that considerably less electric current flow to terminal.Usually, this impedance effect is realized by the filter circuit in the converter head and to the extra compensation of the transmission line effect from the converter head to the terminal.

Herein, method is to utilize transmission line effect so that realize required distribution of impedance, as Figure 10 explanation.By impedance termination 174 being connected to sensor head 56, realize required impedance variation be similar to triaxle cable shown in Figure 9 140 (its electrical length is 1/4 wavelength) under the maximum operating frequency of RF sensor.Under low frequency, the electrical length of cable 168 is actually zero, and the being seen impedance of adapter is the impedance of terminal.Yet, under maximum frequency, the being seen impedance of transmission line effects invert adapter.For voltage pickup 96, the high impedance terminal is served as low impedance termination under high-frequency, and the low impedance termination of electric current is served as the high impedance terminal under high-frequency.

Transducer allows to realize required terminal impedance, keeps the reflexless terminal at RF connector place simultaneously.Low be used for voltage signal, and height is used for current signal to low transducer 188 to high impedance transformer 184.In RF and microwave circuit, use transducer through good establishment.Yet the general target of these known uses is matched loads, and target in this case is incoordination load wittingly.

The parts list of Fig. 1 to 10

10 RF sensors

14 sensor shell

18 center conductors

22 dielectric materials

26 capacitive characters (voltage) adapter

30 current pickup

34 plugs connect

38 filter circuits

42 curves

46 curves

50 sensor pack

56 closure members

57 openings

60 conductors

66 7 capacitive pickup

68 electric field lines

70 direction of current

74 magnetic lines of flux

78 current pickup

80 current pickup

84 metal levels

88 metal levels

92 circuit boards

96 capacitive pickup

100 collection skin screen layers

108 RF connectors

110 strain relief member and shielding

112 top shield

120 shielding through holes

130 balanced top shield

134 metallization

138 metallization

140 triaxle cables

142 outer jackets

144 outer braid

148 concentric cable

150 concentric cable

152 coaxial conductors

156 dielectric materials layers

174 impedance termination

184 transducers

188 transducers

Although with reference to clearly showing as preference pattern illustrated among the figure and having described the present invention, be understood by those skilled in the art that, in the various changes that can realize therein without departing from the spirit and scope of the present invention on the details.

Claims (21)

1. one kind is used to measure by high power RF power supply and is fed to the RF electric current of plasma process chamber of microelectronics handling implement and the Micro RF sensor pack of voltage, and described subassembly comprises:

Sensor head;

Conductor;

Voltage pickup; And

Current pickup, in described voltage pickup and the described current pickup each is arranged in the described sensor head, each in wherein said voltage pickup and the described current pickup in described sensor head with respect to described conductor stack over each other.

2. sensor pack according to claim 1, at least one in wherein said current pickup and the described voltage pickup is arranged in the printed circuit board (PCB).

3. sensor pack according to claim 2, each in wherein said voltage pickup and the described current pickup is arranged in the described printed circuit board (PCB).

4. sensor pack according to claim 2, wherein current pickup is two inductors that layer forms by described printed circuit board (PCB), described layer engages by blind via hole.

5. sensor pack according to claim 2, wherein said sensor head is defined by the multiaspect closure member, and described conductor is formed by the strip conductor of plasma tool, and described conductor further forms a side of described closure member.

6. sensor pack according to claim 5, wherein said circuit board are arranged in the described multiaspect closure member, and described circuit board comprises a plurality of shielding through holes that are provided with around its outer periphery.

7. sensor pack according to claim 6, wherein said printed circuit board (PCB) comprise and are used to make described conductor smooth so that produce the member of constant-gain to the response of frequency.

8. sensor pack according to claim 7, wherein said response flat member comprise near the kelvin effect screen layer that is arranged on the described conductor, described layer be response to serve as low-pass filter.

9. sensor pack according to claim 2, wherein said voltage pickup comprises the metal level of described printed circuit board (PCB), it has grid or the web frame that is parallel to from the direction orientation of the magnetic lines of flux of described conductor.

10. sensor pack according to claim 2, wherein said printed circuit board (PCB) comprise and are used to stop that any field is coupled to the connector that is connected with described sensor head and the shielding part of cable.

11. sensor pack according to claim 10, wherein said printed circuit board (PCB) comprise the metal top layer of ground connection.

12. sensor pack according to claim 2, it comprises the triaxle cable that is connected to described sensor head, and described cable holding carrying is from two concentric cable of the voltage and current signal of described sensor.

13. the dielectric layer that sensor pack according to claim 12, wherein said triaxle cable comprise the outer, coaxial conductor and be arranged on described outer, coaxial conductor top.

14. sensor pack according to claim 13, it comprises impedance termination, and wherein said impedance termination is connected to described sensor head by triaxle cable, and the electrical length of described triaxle cable is 1/4 wavelength under the maximum operating frequency of described RF sensor.

15. sensor pack according to claim 14, wherein said impedance termination comprises a pair of transducer, in the described transducer each is used for the voltage and current pickup signal from described sensor head, and described transducer is used to make the load mismatch of each described signal so that isolation to be provided.

16. sensor pack according to claim 15, wherein said to transducer comprise be used for described voltage signal low to high impedance transformer be used for the height of described current signal to the Low ESR transducer.

17. sensor pack according to claim 12, wherein said sensor head comprise the strain relief member that is used to admit the opening of described cable and is attached to described circuit board.

18. sensor pack according to claim 17, wherein said strain relief member comprises electric shield spare.

19. a sensor pack, it comprises:

Sensor head, it comprises multiaspect dielectric closure member;

Conductor, it is arranged to a side of described sensor head, and described conductor is the conductor bar of plasma process tools;

Current pickup;

Voltage pickup, each in described current pickup and the described voltage pickup is arranged in the printed circuit board (PCB), and wherein said voltage pickup and described current pickup are arranged in each other above the top and described conductor.

20. sensor pack according to claim 19, wherein said current pickup is fixed by the pair of parallel stratum boundary of described plate, thereby described parallel layers is connected by blind via hole forms inductor.

21. sensor pack according to claim 20, wherein said voltage pickup are the metal levels that is formed by net or lattice structure, described net or lattice structure are oriented on the direction that is parallel to the EM field that is produced by described conductor.

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