CN112820614A

CN112820614A - Plasma cleaning equipment

Info

Publication number: CN112820614A
Application number: CN202011645379.3A
Authority: CN
Inventors: 孔令民; 钟军勇; 谢育林; 朱霆; 贺岳; 钟恒; 邵文林; 张凯
Original assignee: Shenzhen Tete Semiconductor Equipment Co ltd
Current assignee: Shenzhen Tete Semiconductor Equipment Co ltd
Priority date: 2020-12-31
Filing date: 2020-12-31
Publication date: 2021-05-18

Abstract

The present invention provides a plasma cleaning apparatus, including: the base frame is provided with a vacuum cavity; the anode and the cathode bracket are used for supporting the chip, the cathode bracket and the anode are arranged on the base frame and form the vacuum cavity in a surrounding mode, or the cathode bracket and the anode are arranged in the vacuum cavity. The chip is placed on the cathode bracket, the negative electrons move from the anode to the cathode under the action of the cathode electric field, impact is formed on the chip placed on the cathode bracket, and therefore tiny dust on the chip can be cleaned.

Description

Plasma cleaning equipment

Technical Field

The invention relates to the technical field of chip manufacturing, in particular to plasma cleaning equipment.

Background

The cleaning of semiconductor chips is a very important step in the manufacturing process of semiconductor chips, and because each element and connecting wire in an integrated circuit are very fine, if the integrated circuit is polluted by dust particles and metal in the manufacturing process, the functions of the circuits in the chips are easily damaged, short circuits or open circuits are formed, and the circuits are failed. Therefore, in addition to removing external contamination sources during the fabrication process, the integrated circuit fabrication steps, such as high temperature diffusion, ion implantation, etc., require cleaning. The plasma cleaning is to use inert gas to remove foreign matters such as micro-dust, metal ions and organic matters remained on the wafer on the premise of not damaging the surface characteristics and the electrical characteristics of the wafer, so that the reliability and the timeliness of the chip can be ensured. In the prior art, an electric field is generally utilized to electrolyze an inert gas to generate positive ions, and the positive ions are utilized to impact the surface of a chip, so that dust particles on the surface of the chip can be cleaned, for example, an argon gas is utilized to clean the chip, because an inert gas molecule generally comprises an atom and a plurality of negative electrons, only one positive electron can be formed by electrolyzing the inert gas molecule in the electric field, the positive electron impacts the chip to remove the dust particles on the surface of the chip, and the mass of the positive electron is heavier, so that the movement speed of the positive electron is not high, the generated number is small, the cleaning efficiency of the chip is low, and the cleaning effect is poor.

Disclosure of Invention

The invention mainly aims to provide plasma cleaning equipment and aims to solve the problem that in the prior art, the cleaning efficiency of the plasma cleaning equipment is low.

In order to achieve the above object, the present invention provides a plasma cleaning apparatus including:

the base frame is provided with a vacuum cavity;

the anode and the cathode bracket are used for supporting the chip, the cathode bracket and the anode are arranged on the base frame and form the vacuum cavity in a surrounding mode, or the cathode bracket and the anode are arranged in the vacuum cavity.

Optionally, the material of the cathode carrier is stainless steel or copper.

Optionally, the vacuum degree of the vacuum chamber is between 20m torr and 50m torr.

Optionally, the plasma cleaning apparatus further includes an insulating layer disposed on the base frame, and the cathode carrier is mounted on the insulating layer.

Optionally, the plasma cleaning apparatus further includes a vacuum pump and an air pump, an air suction port of the vacuum pump is communicated with the vacuum chamber, and the air pump is communicated with the vacuum chamber to fill the inert gas into the vacuum chamber.

Optionally, the inert gas is pure argon or the inert gas is an argon-oxygen mixed gas containing less than 2% oxygen.

Optionally, the plasma cleaning apparatus further comprises a first sealing member and a second sealing member, the first sealing member being disposed on the anode;

the base frame is provided with a lower cavity and a bearing plate sleeved outside the lower cavity, the anode is in butt joint with the lower cavity to form the vacuum cavity, and the first sealing element and the second sealing element are respectively abutted against two sides of the bearing plate to seal the vacuum cavity.

Optionally, a first positioning element is arranged on the anode, a second positioning element is arranged on the lower cavity and/or the base frame, a fitting piece is arranged at a position on the bearing plate corresponding to the first positioning element and the second positioning element, and the first positioning element and the second positioning element are respectively matched with the fitting piece to form a positioning structure so as to position the anode.

Optionally, the first positioning element and/or the second positioning element are elastic protrusions, and the mating element is a positioning hole.

Optionally, the plasma cleaning device further comprises a lifting assembly, and the lifting assembly is connected with the anode to drive the anode to lift.

According to the technical scheme, the vacuum cavity is formed in the base frame, the cathode bracket and the anode are arranged on the base frame and form the vacuum cavity in a surrounding mode, or the cathode bracket and the anode are arranged in the vacuum cavity. The chip is placed on the cathode bracket, the negative electron moves from the anode to the cathode under the action of the cathode electric field, and impact is formed on the chip placed on the cathode bracket, so that dust particles on the chip can be cleaned, two negative electrons can be decomposed by one argon molecule, and the negative electron amount which is twice that of positive electrons can be generated, so that the more efficient cleaning effect is achieved, meanwhile, the mass of the negative electrons is lighter than that of positive electrons, the movement rate in the vacuum cavity is higher than that of the positive electrons, and the cleaning effect on the chip is improved.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the structures shown in the drawings without creative efforts.

FIG. 1 is a schematic structural diagram of a plasma cleaning apparatus according to an embodiment of the present invention;

FIG. 2 is an exploded view of the plasma cleaning apparatus of the present invention;

FIG. 3 is an enlarged view of a portion of FIG. 2;

FIG. 4 is a schematic view of an assembly structure of a cathode bracket, an insulating frame and a limiting block of the plasma cleaning apparatus of the present invention;

FIG. 5 is a schematic structural view of an anode of the plasma cleaning apparatus according to the present invention;

fig. 6 is a partially enlarged view of fig. 5 at B.

The reference numbers illustrate:

reference numerals	Name (R)	Reference numerals	Name (R)
				10	Base frame	16	Visual mirror
11	Bearing plate	171	First positioning piece
				12	Lower cavity	172	Second positioning piece
13	Anode	181	First seal member
				14	Cathode bracket	182	Second seal
15	Insulating frame	19	Limiting block

The implementation, functional features and advantages of the objects of the present invention will be further explained with reference to the accompanying drawings.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

It should be noted that all the directional indicators (such as up, down, left, right, front, and rear … …) in the embodiment of the present invention are only used to explain the relative position relationship between the components, the movement situation, etc. in a specific posture (as shown in the drawing), and if the specific posture is changed, the directional indicator is changed accordingly.

In addition, the descriptions related to "first", "second", etc. in the present invention are for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In addition, technical solutions between various embodiments may be combined with each other, but must be realized by a person skilled in the art, and when the technical solutions are contradictory or cannot be realized, such a combination should not be considered to exist, and is not within the protection scope of the present invention.

As shown in fig. 1 and 2, in order to achieve the above object, the present invention provides a plasma cleaning apparatus, including:

a pedestal 10, wherein a vacuum chamber (not shown) is disposed on the pedestal 10;

an anode (not shown) and a cathode bracket 14 for holding the chip, wherein the cathode bracket 14 and the anode are mounted on the base frame 10 and enclose the vacuum chamber, or the cathode bracket 14 and the anode are mounted in the vacuum chamber.

The plasma cleaning device provided by the embodiment is used for cleaning semiconductor chips, such as micro dust, soldering flux, metal ions, glue, organic matters and the like on the semiconductor chips. The plasma cleaning equipment comprises a pedestal 10, a cathode bracket 14, an anode and a controller, wherein the controller is electrically connected with the cathode bracket 14 and the anode, an application program for controlling the electrification of the cathode bracket 14 and the anode is stored in the controller, the content of the control of the application program comprises but is not limited to the electrification intensity and the electrification duration of radio frequency current, in addition, a mapping curve of the electrification duration and the radio frequency current intensity is stored in the controller, when the radio frequency current intensity changes or the electrification duration changes, the controller adjusts cleaning parameters according to the mapping curve, the cathode bracket 14 and the anode are both connected with a radio frequency power supply (not shown in the figure), and the radio frequency power supply provides radio frequency current for the cathode bracket 14 and the anode. The base frame 10 is a mounting base for a cathode bracket 14 and an anode, wherein the cathode bracket 14 is used for carrying a chip, an electric field is formed in a vacuum chamber after the anode and the cathode bracket 14 are electrified, the electric field is used for decomposing inert gas, the vacuum chamber is communicated with an air pump (not shown in the figure), the vacuum chamber is filled with the inert gas by the air pump, and after the electric field is electrified, the inert gas is electrolyzed to generate positive ions and negative ions. Taking argon as an example, argon molecules have a positive atom and two negative electrons, argon is decomposed into a positive electron and two negative electrons in the electric field in the vacuum cavity, because the chip is placed on the cathode bracket 14 in the embodiment, the negative electrons move from the anode to the cathode under the action of the cathode electric field, and impact is formed on the chip placed on the cathode bracket 14, so that dust particles on the chip can be cleaned, and the two negative electrons can be decomposed by one argon molecule, therefore, compared with the cleaning of the chip by using the positive electron, the cleaning mode by using the negative electrons can generate the negative electron amount which is twice as much as the positive electron, the cleaning effect with higher efficiency is achieved, meanwhile, the mass of the negative electrons is lighter than that of the positive electrons, the moving speed in the vacuum cavity is higher than that of the positive electrons, and the cleaning effect on the chip is good.

In this embodiment, after the cathode bracket 14 and the anode are electrified, an electric field is formed in a vacuum chamber, the vacuum chamber includes an anode 13 and a lower chamber 12, the anode 13 is in a cover shape, and the lower chamber 12 is in a plate-shaped structure. The anode 13 can be separated from or abutted against the lower chamber 12, when the anode 13 is abutted against the lower chamber 12, the anode 13 and the lower chamber 12 surround to form the vacuum chamber, and when the anode 13 is separated from the lower chamber 12, the chip can be placed on the cathode bracket 14. The vacuum chamber can be directly surrounded by the cathode bracket 14 and the anode, at this time, the whole anode 13 is the anode, in this embodiment, the conductive metal (such as copper, aluminum, stainless steel, etc.) is the constituent material of the anode, the cathode can be made of copper or stainless steel, the copper and the stainless steel have good oxidation resistance, the cathode oxidation can be avoided, and the plasma cleaning equipment can be ensured to have a long service life.

In another embodiment, the vacuum chamber may be formed first, and then the anode is fixed on the upper chamber, and the cathode bracket 14 is mounted on the lower chamber 12 (of course, the anode may also be mounted on the lower chamber 12, and the cathode bracket 14 is mounted on the upper chamber, which may be implemented as required).

The separation and butt joint of the anode 13 and the lower cavity 12 are driven by a lifting assembly, the lifting assembly can be specifically a servo motor and a transmission assembly or a cylinder and a transmission assembly, the lifting assembly is connected with the anode 13, and the anode 13 is driven to ascend or descend when a control instruction of a controller is received.

The vacuum chamber is communicated with a suction port 20 of the vacuum pump, and the vacuum pump vacuumizes the vacuum chamber to enable the vacuum degree of the vacuum chamber to reach the set value of the controller, wherein in one embodiment, the vacuum degree of the vacuum chamber is in the range of 20-50 m torr, so that the negative electrons can reach enough movement speed under the vacuum degree to impact the micro-dust on the chip. In practical application, the chip is required to be subjected to cleanliness detection after being cleaned in a vacuum cavity, when the cleanliness is detected, water drops are dropped on the chip, a water drop angle formed by the water drops on the surface of the chip is detected by using detection equipment, the higher the cleanliness of the surface of the chip is, the more divergent the water drops are, the smaller the formed water drop angle is, and the plasma cleaning equipment provided by the invention can enable the water drop angle to be smaller than 8 degrees (between 5 degrees and 8 degrees), so that the cleaning effect is good. It can be understood that the same chip may need to be cleaned for multiple times, when the chip is taken out of the vacuum chamber, the vacuum chamber is broken by the vacuum pump, then the anode 13 is lifted by the lifting assembly, after the chip is placed on the cathode bracket 14, the anode 13 is lowered by the lifting assembly, as shown in fig. 3, 5 and 6, the anode 13 is provided with a first sealing member 181, the lower chamber 12 is provided with a second sealing member 182, the base frame 10 is provided with the bearing plate 11, the bearing plate 11 is sleeved outside the lower chamber 12, and the first sealing member 181 and the second sealing member 182 are respectively abutted against the upper side and the lower side of the bearing plate 11 to form a sealing structure. The first sealing element 181 and the second sealing element 182 may be both convex sealing rings (e.g., silica gel ribs), and when the first sealing ring and the second sealing ring are both abutted to the bearing plate 11 and then pre-compressed by the gravity of the anode 13, the vacuum chamber is evacuated by the vacuum pump, so that the first sealing ring and the second sealing ring are gradually compressed to seal the vacuum chamber.

The lifting assembly is controlled by the control element, and the path for driving the anode 13 to lift is uniquely determined, therefore, the lifting path of the anode 13 is precisely controllable, no error exists when the anode 13 is butted with the lower cavity 12, in order to avoid the relative movement of the anode 13 and the lower cavity 12 in the vacuum pumping process, the anode 13 is provided with the first positioning element 171, the lower cavity 12 and/or the base frame 10 is provided with the second positioning element 172, the positions of the bearing plate 11 corresponding to the first positioning element 171 and the second positioning element 172 are provided with the matching elements (such as positioning holes or positioning protrusions, which are not marked in the figure), and the first positioning element 171 and the second positioning element 172 are respectively matched with the matching elements on the bearing plate 11 to form a positioning structure.

In a further embodiment, the first positioning element 171 and/or the second positioning element 172 are/is an elastic protrusion, so that the first positioning element 171 and/or the second positioning element 172 can be elastically deformed when being pressed, so as to adapt to the change of the distance between the anode 13 and the lower chamber 12 caused by the compression of the first sealing ring and the second sealing ring when the vacuum degree of the vacuum chamber is increased. In this embodiment, the first positioning element 171 and the second positioning element 172 may be both elastic protrusions, or only one of them may be an elastic protrusion (at this time, the mating element is a positioning hole), and the other one may be a groove or a protrusion that cannot be deformed.

In order to prevent the cathode 14 from being electrically connected to the anode, as shown in fig. 4, the plasma cleaning apparatus further includes an insulating layer disposed on the base frame 10, and the cathode 14 is disposed on the insulating layer. In this embodiment, the insulating layer is an insulating frame 15, and cathode bracket 14 is a plurality of stainless steel strips or copper strips that the interval set up on insulating frame 15, and the negative electron moves the chip on the impact cathode bracket 14 to cathode bracket 14 under the effect of electric field, reaches the purpose of washing the chip. In order to ensure the stable installation, the insulating frame 15 is further provided with a limiting block 19, and the limiting block 19 is arranged between the bearing plate 11 and the insulating frame 15.

The inert gas may be pure argon gas or an argon-oxygen mixed gas containing 2% or less of oxygen gas, or may be an argon-hydrogen mixed gas containing hydrogen gas. The flux on the chip surface and H, O, C contained in the organic matter are generated into water, CO and CO by oxygen or oxyhydrogen₂And separating from the surface of the chip.

The rf power source illuminates the vacuum chamber when the cathode carrier 14 and anode are energized, and a visual mirror 16 may be provided on the anode to allow the operator to know the chip cleaning status in a timely manner.

The above description is only an alternative embodiment of the present invention, and not intended to limit the scope of the present invention, and all modifications and equivalents of the present invention, which are made by the contents of the present specification and the accompanying drawings, or directly/indirectly applied to other related technical fields, are included in the scope of the present invention.

Claims

1. A plasma cleaning apparatus, characterized by comprising:

the base frame is provided with a vacuum cavity;

2. The plasma cleaning apparatus according to claim 1, wherein the material of the cathode holder is stainless steel or copper.

3. The plasma cleaning apparatus of claim 1, wherein a degree of vacuum of the vacuum chamber is in a range of 20-50 m torr.

4. The plasma cleaning apparatus of claim 1, further comprising an insulating layer disposed on the pedestal, the cathode carrier being mounted on the insulating layer.

5. The plasma cleaning apparatus according to claim 1, further comprising a vacuum pump having a suction port communicating with the vacuum chamber, and an air pump communicating with the vacuum chamber to fill the vacuum chamber with an inert gas.

6. The plasma cleaning apparatus according to claim 5, wherein the inert gas is pure argon gas or the inert gas is an argon-oxygen mixed gas containing 2% or less of oxygen gas.

7. The plasma cleaning apparatus of claim 1, further comprising a first seal member and a second seal member, the first seal member being disposed on the anode;

8. The plasma cleaning apparatus according to claim 7, wherein a first positioning member is disposed on the anode, a second positioning member is disposed on the lower cavity and/or the base frame, a mating member is disposed on the loading plate at a position corresponding to the first positioning member and the second positioning member, and the first positioning member and the second positioning member are respectively mated with the mating member to form a positioning structure for positioning the anode.

9. The plasma cleaning apparatus according to claim 8, wherein the first positioning member and/or the second positioning member is an elastic protrusion, and the engaging member is a positioning hole.

10. The plasma cleaning apparatus of claim 7, further comprising a lifting assembly coupled to the anode to lift the anode.