CN112708865B

CN112708865B - Coating equipment for improving film uniformity

Info

Publication number: CN112708865B
Application number: CN202110330031.3A
Authority: CN
Inventors: 周云; 宋维聪; 解文骏; 方合
Original assignee: Shanghai Betone Semiconductor Energy Technology Co ltd
Current assignee: Shanghai Betone Semiconductor Energy Technology Co ltd
Priority date: 2021-03-29
Filing date: 2021-03-29
Publication date: 2021-07-09
Anticipated expiration: 2041-03-29
Also published as: CN112708865A

Abstract

The invention provides a coating device for improving the uniformity of a film, which comprises: the wafer substrate comprises a substrate surface and a flat electrode positioned below the substrate surface, the flat electrode is used for providing a bias field, the flat electrode is divided into a plurality of electrode areas by one or more insulating rings, and each electrode area divided by the insulating rings can independently generate a pulse direct current bias voltage or a radio frequency bias voltage so as to generate the same or different negative bias voltages in different areas of the wafer surface. According to the invention, by partitioning the flat plate electrode, different bias voltages can be set according to the process requirements of different areas on the surface of the wafer, and the stress uniformity and the sheet resistance uniformity of the deposited film are optimized by adjusting the resistance values of the series resistors in each electrode area, so that the quality of the deposited film can be greatly improved, and the production yield is improved.

Description

Coating equipment for improving film uniformity

Technical Field

The invention belongs to the field of semiconductor manufacturing equipment, and particularly relates to coating equipment for improving the uniformity of a film.

Background

For the sputtering coating process, metal particles sputtered from the surface of the target react with the reaction gas and finally deposit on the surface of the wafer to form a film. Various parameters in the sputtering coating process, including magnetic field distribution on the surface of the target material, gas flow and pressure, reaction temperature, negative bias of the substrate and the like, can all have important influence on the quality of the film; the influence of the magnetic field on the surface of the target and the negative bias of the substrate is particularly prominent. For example, the magnetic field on the surface of the target has great influence on the film characteristics such as sheet resistance uniformity, stress uniformity and the like; the negative bias has great influence on the film characteristics, and the negative bias can increase the energy of the positive ions bombarding the deposited film on the surface of the wafer by increasing the substrate bias and the energy of the positive ions bombarding the deposited film, so that the stress of the film can be changed from tensile stress to compressive stress, and the density of the sputtered film can be increased, thereby changing the sheet resistance of the film. However, for a common magnetron sputtering apparatus, the uniformity of the magnetic field on the surface of the target is often difficult to satisfy, and one of the main reasons is that the design of the magnetron on the back of the target in the common coating apparatus is designed to improve the uniformity of the film thickness and the utilization rate of the target, so that it is difficult to achieve both the sheet resistance uniformity and the stress uniformity of the sputtered film. The magnetron designed in this way causes great difference in the distribution of inert gas ions in the central area and the peripheral area of the wafer, and the bombardment energy of the non-uniformly distributed ions to the film on the surface of the wafer is also different, thereby affecting the stress uniformity and sheet resistance uniformity of the film on the surface of the wafer.

Disclosure of Invention

In view of the above-mentioned shortcomings of the prior art, the present invention is directed to a coating apparatus for improving film uniformity, which is used to solve the problem in the prior art that the uniformity of stress and sheet resistance of the film on the surface of the wafer is difficult to improve.

To achieve the above and other related objects, the present invention provides a coating apparatus for improving uniformity of a thin film, the coating apparatus comprising: the wafer pedestal comprises a pedestal surface and a flat plate electrode positioned below the pedestal surface, the flat plate electrode is used for providing a bias field, the flat plate electrode is divided into a plurality of electrode areas by one or more insulating rings, and each electrode area divided by the insulating rings can independently generate a pulse direct current bias or a radio frequency bias so as to generate the same or different negative biases in different areas of the wafer surface.

Optionally, the coating apparatus is a sputtering coating apparatus, the deposition source includes a magnet and a target, the target is located at an upper portion of the cavity, and the magnet is located above the target.

Optionally, the coating device is a chemical vapor deposition device or an atomic layer deposition device, and the deposition source is a shower head used for thin film deposition.

Optionally, each electrode area on the plate electrode is connected with a power supply, and the negative bias voltage of each electrode area is changed by changing the output power of the power supply.

Optionally, the power supply includes one of a dc power supply, a pulsed dc power supply, and a radio frequency power supply.

Optionally, each electrode region is connected in series with a variable resistor, and the negative bias voltage of each electrode region is adjusted by adjusting the resistance value of the variable resistor.

Optionally, the magnitude of the negative bias voltage of each of the electrode regions is set according to stress or/and sheet resistance requirements of different regions of the wafer surface.

Optionally, the energy of the positive ions near the upper surface of the wafer bombarding different areas of the surface of the wafer downwards is adjusted through the attraction and acceleration effects of different negative bias voltage on the positive ions, so as to improve the stress uniformity and the sheet resistance uniformity of the deposited film on the surface of the wafer.

Optionally, the plate electrode is divided into a plurality of circular electrode regions or annular electrode regions by one or more insulating rings.

Optionally, a heating plate is further disposed inside the wafer pedestal, the heating plate includes a single heating block or one of a plurality of heating blocks, and each heating block of the plurality of heating blocks can independently control heating power to improve heating uniformity and improve uniformity of stress and sheet resistance of a deposited film on the surface of the thin film wafer.

Optionally, the cavity inboard still is equipped with the heating plate, the heating plate is cyclic annular symmetric distribution, just the heating plate sets up in wafer top or at same level with the wafer.

Optionally, a rotating device is further disposed below or outside the wafer pedestal, so that the flat plate electrode can rotate continuously or discontinuously during the process.

As described above, the coating apparatus for improving the uniformity of a thin film according to the present invention has the following advantageous effects:

the film coating equipment provided by the invention is provided with the flat plate electrode and partitions the flat plate electrode, each electrode area can independently generate a pulse direct current bias voltage or a radio frequency bias voltage so as to generate the same or different negative bias voltages in different areas of the surface of the wafer, so that different bias voltage sizes can be set according to the process (such as stress and sheet resistance) requirements of different areas of the surface of the wafer, the stress uniformity and sheet resistance uniformity of a deposited film are optimized by adjusting the resistance values of series resistors in each electrode area, the quality of the deposited film can be greatly improved, and the production yield is improved. Experiments prove that the invention can greatly reduce the uniformity (difference between the maximum stress and the minimum stress) of the in-chip stress of the film on the surface of the wafer by realizing independent bias control on a plurality of electrode areas of the flat electrode.

Drawings

Fig. 1 is a schematic structural diagram of a coating apparatus for improving film uniformity according to an embodiment of the present invention.

FIG. 2 is a schematic structural diagram of a plate electrode of the coating apparatus for improving film uniformity according to the present invention.

FIG. 3 is a schematic structural diagram of a coating apparatus with a wafer pedestal having a rotation device according to an embodiment of the present invention.

Fig. 4 is a graph showing stress uniformity of a nitride thin film deposited by a coating apparatus using a single electrode.

FIG. 5 is a graph showing the stress uniformity of a nitride film deposited by a three-electrode zone coating apparatus according to an embodiment of the present invention.

Element number description: 10, a cavity; 11 a target material; 12 a magnet; 13 a wafer pedestal; 131 flat electrodes; 132 a base surface; 311 electrode regions; 312 an insulating ring; 133 heating the disc; a 151 motor; 152 a drive connection; 153 rotating member.

Detailed Description

The embodiments of the present invention are described below with reference to specific embodiments, and other advantages and effects of the present invention will be easily understood by those skilled in the art from the disclosure of the present specification. The invention is capable of other and different embodiments and of being practiced or of being carried out in various ways, and its several details are capable of modification in various respects, all without departing from the spirit and scope of the present invention.

As in the detailed description of the embodiments of the present invention, the cross-sectional views illustrating the device structures are not partially enlarged in general scale for convenience of illustration, and the schematic views are only examples, which should not limit the scope of the present invention. In addition, the three-dimensional dimensions of length, width and depth should be included in the actual fabrication.

For convenience in description, spatial relational terms such as "below," "beneath," "below," "under," "over," "upper," and the like may be used herein to describe one element or feature's relationship to another element or feature as illustrated in the figures. It will be understood that these terms of spatial relationship are intended to encompass other orientations of the device in use or operation in addition to the orientation depicted in the figures. Further, when a layer is referred to as being "between" two layers, it can be the only layer between the two layers, or one or more intervening layers may also be present.

In the context of this application, a structure described as having a first feature "on" a second feature may include embodiments in which the first and second features are formed in direct contact, and may also include embodiments in which additional features are formed in between the first and second features, such that the first and second features may not be in direct contact.

It should be noted that the drawings provided in the present embodiment are only for illustrating the basic idea of the present invention, and the drawings only show the components related to the present invention rather than being drawn according to the number, shape and size of the components in actual implementation, and the type, quantity and proportion of each component in actual implementation may be changed arbitrarily, and the layout of the components may be more complicated.

The invention aims to provide a coating device for improving the uniformity of a film, which is used for solving the problem that the stress uniformity and sheet resistance uniformity of the film on the surface of a wafer are difficult to improve in the prior art.

To achieve the above and other related objects, as shown in fig. 1 to 2, the present embodiment provides a coating apparatus for improving uniformity of a thin film, where the coating apparatus may be a Physical Vapor Deposition (PVD) apparatus, a Chemical Vapor Deposition (CVD) apparatus, an Atomic Layer Deposition (ALD) apparatus, and the like, and in the present embodiment, the coating apparatus is a Physical Vapor Deposition (PVD) apparatus, specifically a sputtering coating apparatus, and the coating apparatus includes: the sputtering coating device comprises a cavity 10, a deposition source and a wafer base 13, wherein the deposition source of the sputtering coating device comprises a magnet 12 and a target 11. Of course, for a chemical vapor deposition apparatus or an atomic layer deposition apparatus, the deposition source may be a showerhead used for thin film deposition.

The target 11 is located at the upper part of the cavity 10, the magnet 12 is located above the target 11, the target 11 is bombarded by plasma (such as argon gas, etc.), and after the raw material on the target 11 is sputtered, the raw material is directly deposited on the surface of the wafer, or reaction gas is introduced to form a film of the required material component on the surface of the wafer.

The wafer pedestal 13 is located at the lower portion of the chamber 10, the wafer pedestal 13 includes a pedestal surface 132 and a plate electrode 131 located below the pedestal surface 132, and the pedestal surface 132 may be made of graphite, stainless steel, aluminum, or other materials for supporting a wafer. The plate electrode 131 is used for providing a bias field, the plate electrode 131 is divided into a plurality of electrode regions 311 by one or more insulating rings 312, and each electrode region divided by the insulating ring 312 can independently generate a pulsed dc bias or an rf bias to generate the same or different negative biases at different regions of the wafer surface.

In one embodiment, each electrode region 311 on the plate electrode 131 is connected with a power supply, and the magnitude of the negative bias voltage of each electrode region 311 is changed by changing the magnitude of the output power of the power supply. Illustratively, the power source comprises one of a dc power source, a pulsed dc power source, and a radio frequency power source. In this embodiment, the power supply is a pulsed dc power supply.

In another embodiment, each electrode region 311 on the flat plate electrode 131 is connected to a power supply, and each electrode region is connected in series with a variable resistor, and the negative bias voltage of each electrode region 311 is adjusted by adjusting the resistance of the variable resistor.

The magnitude of the negative bias voltage for each of the electrode regions 311 is set according to the stress or/and sheet resistance requirements of different regions of the wafer surface. Through the attraction and acceleration effects of different negative bias voltages on positive ions, the energy of the positive ions near the upper surface of the wafer for downwards bombarding different areas of the surface of the wafer is adjusted so as to improve the stress uniformity and the sheet resistance uniformity of the deposited film on the surface of the wafer. Specifically, when the stress of a certain region of the wafer is a compressive stress with more negative, the negative bias of the electrode region 311 can be reduced by increasing the resistance of the variable resistor corresponding to the electrode region 311, so that the energy of the ion bombardment of the region on the wafer can be reduced, and the purpose of reducing the compressive stress of the region can be achieved; when the stress of a certain area of the wafer is the negative pressure stress with smaller negative, the negative bias of the electrode area 311 can be increased by reducing the resistance value of the variable resistor corresponding to the electrode area 311, so that the energy of the ion bombardment of the area on the wafer can be improved, the purpose of increasing the pressure stress of the area is achieved, accordingly, the stress uniformity and the sheet resistance uniformity of the deposited film can be effectively optimized, the quality of the deposited film can be greatly improved, and the production yield is favorably improved.

As shown in fig. 2, the plate electrode 131 is divided into a plurality of circular electrode regions 311 or annular electrode regions 311 by one or more insulating rings 312. In the present embodiment, the overall shape of the plate electrode 131 is a circle, and the size of the circle may be the same as the size of the wafer or slightly larger than the wafer. The plate electrode 131 is divided into 3 electrode regions 311 by 3 insulating rings 312, a circular electrode region 311 is located in the middle of the plate electrode 131, and a ring electrode region 311 is located in the middle and outside of the plate electrode 131. Of course, in other embodiments, one or more strip-shaped insulating lines extending in the diameter direction may be added to the plate electrode 131 to divide the plate electrode 131 into more electrode regions 311, so as to improve the more precise control of the negative bias voltage.

In another embodiment, the flat-plate electrode 131 may also be an asymmetric or irregular distribution region, for example, the electrode region 311 may also be a diamond grid or a rectangular grid, or other irregular shapes or arrangements; when the electrode region 311 is asymmetric or irregular, a rotation device may be added below or outside the wafer pedestal 13, so that the plate electrode 131 may rotate continuously or discontinuously during the process, and a symmetric bias distribution may be obtained on the wafer surface, and a symmetric ion energy distribution may be obtained based on the symmetric bias distribution, which is beneficial to the adjustment and optimization of stress uniformity. Of course, for the plate electrodes 131 with symmetrical or regular electrode regions 311, a rotating device may be added below or outside the wafer pedestal 13 to further improve the symmetry and uniformity of the distribution of the negative bias voltage on the wafer surface.

As shown in fig. 3, the rotating device includes a motor 151 and a transmission connector 152, and the transmission connector 152 includes a belt or a gear. The rotating member 153 is connected to the motor 151 through a belt or a gear, and is rotated by the motor 151, and since the wafer susceptor 13 is connected to the rotating member 153, the wafer susceptor 13 and the plate electrode 131 are continuously or discontinuously rotated by the motor 151.

As shown in fig. 1, in the present embodiment, a heating plate 133 is further disposed inside the wafer pedestal 13, the heating plate 133 includes a single heating block or one of a plurality of heating blocks, and each heating block of the plurality of heating blocks can independently control heating power to improve heating uniformity and improve uniformity of stress and sheet resistance of a deposited film on a surface of a thin film wafer.

Of course, in another embodiment, the heating plate 133 may also be disposed inside the chamber, the heating plate 133 is distributed annularly and symmetrically, and the heating plate 133 is disposed above the wafer or at the same level as the wafer to heat the wafer, so as to improve the uniformity of the stress and the sheet resistance of the thin film deposited on the surface of the thin film wafer.

Furthermore, the heating plates 133 can be disposed in the wafer susceptor 13 and inside the chamber, so as to control the temperature of the wafer from the bottom and the side of the wafer, thereby further improving the heating uniformity of the wafer.

As shown in fig. 4 and 5, fig. 4 is a graph showing stress uniformity of a nitride film deposited by a single electrode coating apparatus, fig. 5 is a graph showing stress uniformity of a nitride film deposited by a three-electrode-region coating apparatus according to the present embodiment, and as can be seen from fig. 4 and 5, by implementing independent bias control on three electrode regions of a plate electrode, it is possible to reduce the in-chip stress uniformity (difference between maximum stress and minimum stress) of a nitride film on a wafer surface from 300 MPa (single electrode region) in fig. 4 to about 80MPa (three electrode region) in fig. 5, and the in-chip stress uniformity of a nitride film deposited by a coating apparatus according to the present embodiment is not more than 80 MPa.

Therefore, the invention effectively overcomes various defects in the prior art and has high industrial utilization value.

The foregoing embodiments are merely illustrative of the principles and utilities of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or change the above-mentioned embodiments without departing from the spirit and scope of the present invention. Accordingly, it is intended that all equivalent modifications or changes which can be made by those skilled in the art without departing from the spirit and technical spirit of the present invention be covered by the claims of the present invention.

Claims

1. A coating apparatus for improving uniformity of a thin film, comprising: the wafer base comprises a base surface and a flat plate electrode positioned below the base surface, the flat plate electrode is used for providing a bias field, the flat plate electrode is divided into a plurality of electrode areas by one or more insulating rings, each electrode area divided by the insulating rings can independently generate a pulse direct current bias or a radio frequency bias so as to generate the same or different negative biases in different areas of the wafer surface, each electrode area on the flat plate electrode is connected with a power supply, the size of the negative bias of each electrode area is changed by changing the output power of the power supply, and the energy of positive ions near the wafer surface and downwards bombarding different areas of the wafer surface is adjusted through the attraction and acceleration effects of different negative bias sizes on the positive ions, so as to improve the stress uniformity and sheet resistance uniformity of the deposited film on the surface of the wafer; the surface of the base is made of graphite or aluminum material; the cavity inboard still is equipped with the heating plate, the heating plate is cyclic annular symmetric distribution, just the heating plate sets up in wafer top or at same level with the wafer.

2. The coating apparatus according to claim 1, wherein: the coating equipment is sputtering coating equipment, the deposition source comprises a magnet and a target, the target is positioned at the upper part of the cavity, and the magnet is positioned above the target.

3. The coating apparatus according to claim 1, wherein: the coating equipment is chemical vapor deposition equipment or atomic layer deposition equipment, and the deposition source is a spray header used for film deposition.

4. The coating apparatus according to claim 1, wherein: the power supply comprises one of a direct current power supply, a pulse direct current power supply and a radio frequency power supply.

5. The coating apparatus according to claim 1, wherein: each electrode area is connected with a variable resistor in series, and the negative bias of each electrode area is adjusted by adjusting the resistance value of the variable resistor.

6. The coating apparatus according to claim 5, wherein: the magnitude of the negative bias voltage of each electrode region is set according to the stress or/and sheet resistance requirements of different regions of the wafer surface.

7. The coating apparatus according to claim 1, wherein: the flat electrode is divided into a plurality of circular electrode areas or annular electrode areas by one or more insulating rings.

8. The coating apparatus according to claim 1, wherein: the wafer base is internally provided with a heating plate, the heating plate comprises a single heating block or one of a plurality of heating blocks, and each heating block of the plurality of heating blocks can independently control the heating power so as to improve the heating uniformity and improve the stress uniformity and the sheet resistance uniformity of a film deposited on the surface of the film wafer.

9. The coating apparatus according to claim 1, wherein: and a rotating device is arranged below or outside the wafer base so that the flat electrode can rotate continuously or discontinuously in the process.