TWI590292B - Shielding device and plasma processing device with the shielding device - Google Patents

Description

Shielding device and plasma processing device having the same

The present application claims priority to the Chinese Patent Application No. 201410686564.5, filed on November 25, 2014, to the Chinese National Intellectual Property Office, the entire contents of which is hereby incorporated by reference.

The present invention relates to a semiconductor processing apparatus, and more particularly to a shielding apparatus for selectively preventing passage of charged particles from a plasma and a plasma processing apparatus having the same.

The current plasma processing apparatus is widely used in the technical field of semiconductor device manufacturing as a device for performing various methods such as film formation and etching on a semiconductor wafer. In the plasma processing apparatus, the plasma of the reaction gas is allowed to act on the semiconductor wafer, and the corresponding plasma treatment is performed. Generally, the plasma contains charged particles such as cations and electrons, and free radicals as neutral particles. In some plasma processing technologies, semiconductor wafers are primarily processed using free radicals. For example, the photoresist removal technique requires that the radical react with the photoresist on the surface of the semiconductor wafer. If the charged particles reach the semiconductor wafer, a negative interaction with the semiconductor wafer can result in damage to the semiconductor components on the wafer, so less charged particles are expected to accumulate on the wafer surface.

Chinese Patent No. CN100573830C provides a selective passage unit that selectively passes only radicals, and the selection passage unit is provided with two or more insulating plates formed with a plurality of through openings, such that the positions of the through openings are shifted due to Generally, the cation is attracted by the bias voltage generated by the susceptor and moves in a straight line. Therefore, when the through openings of the two plates are staggered, the cation is passed. The cation of the plate through opening collides with the solid portion of the lower plate and cannot pass through the lower plate, but the radical is randomly moved due to neutral attraction without being biased by the bias voltage, and can still pass through the through opening of the lower plate. The free radicals are selectively passed from the plasma. However, when a high-density plasma is used in order to improve the efficiency of plasma treatment using radicals, the density of cations also increases, and therefore, the probability that cations pass through the above two plates is also increased, and the film on the semiconductor wafer is still There may be damage due to cations.

Chinese Patent CN101919030B provides another solution for electrically grounding a plasma confinement plate having a plurality of radical introduction holes for discharging, thereby preventing charged particles in the plasma from passing through the radical introduction holes. However, this method still cannot completely eliminate the leakage current, and the charged particles cannot be completely shielded.

Accordingly, it is desirable to provide a shielding device that selectively blocks the passage of charged particles from a plasma to improve the above drawbacks.

SUMMARY OF THE INVENTION A primary object of the present invention is to overcome the deficiencies of the prior art and to provide a charged particle shielding device for preventing charged particles from reaching the surface of a substrate by accurately controlling a DC bias to effectively reduce damage to the semiconductor device on the surface of the substrate.

To achieve the above object, the present invention provides a shielding device for selectively preventing passage of charged particles from a plasma generated by a plasma source of a plasma processing apparatus. The shielding device may include: a first shielding plate disposed in a reaction chamber of the plasma processing device, wherein a plurality of first through holes are formed, the first shielding plate has a conductive material, and the conductive material is applied a DC bias; a conductive component disposed in the reaction chamber, a plasma distribution region between the first shield and the plasma source and having a surface exposed to the plasma; a measuring component for measuring Surface of the conductive component a current of the absorbed plasma; and a control component that calculates and controls a bias value and a polarity of the DC bias based on the measurement result of the measuring component.

Preferably, the shielding device may include a second shielding plate disposed in parallel with the first shielding plate, wherein the second shielding plate defines a plurality of second through holes, and the plurality of second through holes and the plurality of through holes The plurality of first through holes do not overlap or partially overlap.

Preferably, the second shielding plate may have a conductive material and the DC bias is applied to the conductive material.

Preferably, the conductive component is disposed at a plurality of locations of the plasma distribution area, and the control component calculates and controls a bias value of the DC bias according to the plurality of measurement results obtained by the measurement component. polarity.

Preferably, the conductive component is affixed to the first shielding plate.

Preferably, the control component controls the polarity of the DC bias according to the polarity of the plasma current detected by the measuring component, and calculates and controls the bias of the DC bias according to the current value of the plasma current. Pressure value.

Preferably, when the measuring component measures the current of the plasma as a positive ion current, the control component controls the polarity of the DC bias to be positive; when the measuring component measures the current of the plasma is The control component controls the polarity of the DC bias to be negative when negative electron current is present.

Preferably, the first shielding plate may be made of a conductive material or coated with a conductive coating on the surface of the non-conductive material.

Preferably, the first shielding plate and the second shielding plate are made of a conductive material or coated with a conductive coating on the surface of the non-conductive material.

According to another aspect of the present invention, there is also provided a plasma processing apparatus comprising: a plasma source; a reaction chamber including a susceptor for mounting a substrate; and the shielding device described above, the shielding device A shield is located above the pedestal within the reaction chamber.

The invention has the beneficial effects that the voltage value and the polarity of the DC bias applied to the shielding plate are determined by detecting the characteristics of the current generated by the plasma, so that the DC bias can be accurately controlled to prevent the charged particles from reaching the surface of the substrate, thereby effectively reducing Small damage to the semiconductor device on the surface of the substrate.

10‧‧‧Reaction chamber

11‧‧‧ Plasma source

12‧‧‧ Pedestal

20‧‧‧Upper shield

21‧‧‧First through hole

22‧‧‧Electrical materials

23‧‧‧Lower shield

24‧‧‧Second through hole

25‧‧‧Electrical materials

30‧‧‧ Conductive components

40‧‧‧Measurement components

50‧‧‧Control components

60‧‧‧DC power supply

W‧‧‧Substrate

Fig. 1 is a schematic view showing a plasma processing apparatus having a shielding device according to an embodiment of the present invention.

Fig. 2 is a schematic view showing a plasma processing apparatus having a shielding device according to another embodiment of the present invention.

In order to make the content of the present invention clearer and easier to understand, the contents of the present invention will be further described below in conjunction with the accompanying drawings. It is a matter of course that the invention is not limited to the specific embodiment, and that the general substitutions well known to those skilled in the art are also encompassed within the scope of the invention.

1 to 2 show a plasma processing apparatus provided by various embodiments of the present invention. It should be understood that it is merely exemplary and that fewer or more component components may be included, or that the components may be arranged differently than the drawings.

Embodiment 1

Referring to FIG. 1, the plasma processing apparatus of the present embodiment includes a reaction chamber 10, a plasma source 11, and a shielding device. The bottom of the reaction chamber 10 is provided with a susceptor 12 for holding the substrate W to be processed; the remote plasma source 11 as a remote plasma source excites the process gas into a plasma and is supplied to the inside of the reaction chamber 10; The passage of charged particles is selectively prevented in the plasma. The plasma source of the present invention is not limited to The remote plasma source may also generate plasma in the reaction chamber 10 by means of inductive coupling (ICP), microwave or the like.

The shielding device has an upper shield plate 20 (ie, a first shield plate), a conductive assembly 30, a measurement assembly 40, and a control assembly 50. The upper shielding plate 20 is disposed above the base 12 in the reaction chamber 10, and can be fixed by a support assembly (not shown). The upper shield plate 20 has a conductive material 22. Further, a plurality of first through holes 21 are formed in the shield plate 20 to pass free radicals in the plasma to reach the substrate W. The upper shield 20 may itself be made of a conductive material or may be coated with a conductive coating on the surface of the non-conductive material. As shown, the conductive material 22 of the upper shield 20 is coupled to a DC power source 60 that applies a DC bias to the shield 20 such that charged particles in the plasma cannot pass through the upper shield 20. Depending on the plasma technology, the properties of the charged particles in the plasma and the kinetic energy distribution will also be different. Therefore, if only the conductive material 22 of the upper shield 20 is applied with a fixed voltage value and a polar DC bias, it is likely to be generated. When the DC bias value is too large or too small, the charged particles pass through the upper shield plate 20. In order to monitor the characteristics of charged particles in the plasma in the reaction chamber in real time and to provide corresponding feedback, the shielding device of the present invention also designs a sensing assembly and control assembly 50. The sensing component includes a conductive component 30 and a measuring component 40. The conductive member 30 is disposed inside the reaction chamber 10, a plasma distribution region between the upper shield plate 20 and the plasma source 11, and has a surface exposed to the plasma, whereby the charged particles bombarded to the surface of the conductive member 30 are electrically conductive. The surface of the assembly forms the current of the plasma. Conductive component 30 is coupled to measurement assembly 40 external to reaction chamber 10, such as by wires. In this embodiment, the measuring component 40 includes a grounded ammeter capable of measuring the positive and negative current of the plasma of the surface of the conductive component 30. When most of the surface of the bombarding conductive component 30 is electron, the current meter measures the current polarity of the plasma as Negatively, when the majority of the surface of the bombarded conductive component 30 is a positive ion, the ammeter measures the polarity of the current of the plasma to be positive. In addition, the ammeter can of course measure the magnitude of the plasma current. The measuring component 40 can also be in other forms, such as a combination of a resistor and a voltmeter, etc., as long as the current magnitude and positive and negative of the plasma absorbed by the surface of the conductive component 30 can be measured. The control assembly 50 is coupled to the measurement assembly 40, based on the measurement of the measurement assembly 40 The quantity result calculates and controls the bias value and polarity of the DC bias applied by the DC power source 60 to the conductive material 22 of the upper shield plate 20. Specifically, the control component 50 controls the polarity of the DC bias according to the polarity of the current of the plasma. In this embodiment, when the measuring component 40 measures the current of the plasma as a positive ion current, it indicates that there are many charged particles in the plasma. For positive ions, the control unit 50 controls the polarity of the DC bias to be positive, and the polarity of the positive ions is the same as the polarity of the DC bias applied to the upper shield 20, so that the positive ions are repulsive from the upper shield 20 The direction away from the substrate W is driven away; when the measuring component 40 measures the current of the plasma as a negative electron current, it indicates that the charged particles in the plasma are mostly electrons, and the control component 50 controls the polarity of the DC bias to be negative, electronic The polarity is the same as the polarity of the DC bias applied to the upper shield plate 20, and therefore, the electrons are also driven away from the substrate W by the repulsive force from the upper shield plate 20. By designing the DC bias applied to the upper shield 20 to be of the same polarity as the plasma current, most of the charged particles forming the plasma current can be shielded or driven away from passing through the upper shield 20. On the other hand, the control unit 50 controls the DC bias voltage to an appropriate voltage value in accordance with the magnitude of the measured plasma current so that all of the charged particles cannot pass through the shield plate 20. For example, if the current measured by the plasma is positive ion current, if the applied positive bias is too small, the positive ions cannot be completely driven away and then pass through the shielding plate; if the applied positive bias is too large, although the positive ions can be driven Off, but the greater the attraction to the electrons in the plasma, so that it is adsorbed on the surface of the shield, and thus may also pass through the shield. Therefore, the control unit 50 is required to control the magnitude of the bias value to ensure only neutral particles. The free radicals pass through the shield 20 to process the substrate W while avoiding the effects of charged particles on the function of the semiconductor components on the substrate W.

The conductive component 30 can be placed anywhere in the plasma distribution region, such as the outlet end of the plasma source 11, i.e., at the top opening of the reaction chamber 10. Preferably, the conductive component 30 is attached to the upper surface of the upper shielding plate 20 as shown in the drawing, such that the characteristics of the plasma received by the conductive component 30 and the upper shielding plate 20 are exactly the same, and the measurement result obtained by the measuring component 40 is obtained. Actually reflecting the current of the plasma absorbed by the surface of the upper shield plate 20, and once the measuring assembly detects the current elimination on the surface of the conductive component 30, it means that all the charged particles are driven away from the upper shield plate 20, thus The control results are more precise. In addition, Although the conductive component 30 is only one in this embodiment, in other embodiments, a plurality of conductive components 30 may be disposed at a plurality of locations in the plasma distribution region, for example, at an edge position of the upper shield 20 and At the center position, the measurement component 40 can obtain a plurality of measurement results, and the control component 50 calculates a plurality of measurement results (such as averaging or other complicated calculations) to obtain more accurate properties of charged particles in the plasma, thereby achieving more For precise DC bias control.

Embodiment 2

Referring to FIG. 2, the difference between this embodiment and the first embodiment is that the shielding device further includes a lower shielding plate 23 (ie, a second shielding plate) disposed above the base 12 and disposed in parallel with the upper shielding plate 20. The lower shield plate 23 has a plurality of second through holes 24, and the positions of the second through holes 24 and the first through holes 21 do not overlap or partially overlap, that is, the first through holes 21 and the second through holes are provided so as not to form a straight line connection. The hole 24, when the charged particles pass through the first through hole 21, collides with the solid portion of the lower shield plate 23, and can further prevent the charged particles from passing through the lower shield plate 23 to reach the substrate W. The size and shape of the first through hole and the second through hole may be arbitrarily set, and the shape and size of each of the through holes in the same shield plate may be different, and the present invention is not limited thereto.

The lower shield plate 23 also has a conductive material 25, and the conductive material 25 is also connected to the DC power source 60 to apply a DC bias. The lower shield plate 23 may itself be made of a conductive material, or the surface of the non-conductive material may be coated with a conductive coating. Since the lower shield plate 23 is also connected to the DC power source 60, the DC bias voltage obtained by the control unit 50 according to the measurement result of the measurement component 40 is also applied to the lower shield plate 23 by the DC power source 60, thereby further enhancing the charged particles. The repulsion plays a better blocking effect.

In summary, the shielding device and the plasma processing device of the present invention obtain the properties of charged particles in the plasma by detecting the characteristics of the current generated by the plasma, thereby accurately controlling the voltage of the DC bias applied to the shield plate. The value and polarity are such as to prevent charged particles from passing through the shielding plate to reach the surface of the substrate, and the present invention can effectively reduce damage to the substrate.

The present invention has been described in terms of the preferred embodiments thereof, and the present invention is intended to be illustrative only, and is not intended to limit the scope of the invention. A number of changes and refinements may be made, and the scope of protection claimed by the present invention shall be as described in the scope of the patent application.

10‧‧‧Reaction chamber

11‧‧‧ Plasma source

12‧‧‧ Pedestal

20‧‧‧Upper shield

21‧‧‧First through hole

22‧‧‧Electrical materials

30‧‧‧ Conductive components

40‧‧‧Measurement components

50‧‧‧Control components

60‧‧‧DC power supply

W‧‧‧Substrate

Claims (8)

A shielding device for use in a plasma processing apparatus for selectively preventing passage of charged particles from a plasma generated by a plasma source of the plasma processing apparatus, comprising: a first shielding plate disposed on a plurality of first through holes are formed in a reaction chamber of the plasma processing device, the first shielding plate has a conductive material, and a constant current bias is applied to the conductive material; a conductive component is disposed in the reaction chamber a plasma distribution region between the first shield plate and the plasma source and having a surface exposed to the plasma; a measuring component for measuring a current of the plasma absorbed by the surface of the conductive component; a control component, calculating and controlling a bias value and a polarity of the DC bias according to the measurement result of the measuring component, wherein the control component controls the polarity of the DC bias according to the polarity of the plasma current detected by the measuring component, according to The current value of the plasma current calculates and controls a bias value of the DC bias; when the measuring component measures the current of the plasma as a positive ion current, the control component controls the DC The polarity is positive pressure; measurement assembly when the measured current of the plasma electron current is negative, the control module controls the DC bias of negative polarity. The shielding device of claim 1, further comprising a second shielding plate disposed in parallel with the first shielding plate, wherein the second shielding plate forms a plurality of second through holes, the plurality of second holes The through hole does not overlap or partially overlap the plurality of first through holes. The shielding device of claim 2, wherein the second shielding plate has a conductive material and the DC bias is applied to the conductive material. The shielding device of claim 1, wherein the conductive component is disposed at a plurality of locations in the plasma distribution region, and the control component calculates and controls the DC bias according to the plurality of measurement results obtained by the measuring component. Bias value and polarity. The shielding device of claim 1, wherein the conductive component is attached to the first shielding plate. The shielding device of claim 1, wherein the first shielding plate is made of a conductive material or a conductive coating is applied on the surface of the non-conductive material. The shielding device of claim 3, wherein the first shielding plate and the second shielding plate are made of a conductive material or coated with a conductive coating on a surface of the non-conductive material. A plasma processing apparatus comprising: a plasma source; a reaction chamber comprising a susceptor for mounting a substrate; and the shielding device according to any one of claims 1 to 7. The shielding plate of the shielding device is located above the base in the reaction chamber.