KR20050058168A - Plasma etching apparatus for simultaneous etching of edge, bevel and back-side of silicon wafer - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor etching apparatus, and more particularly, to a plasma etching apparatus for simultaneously etching edges, sides, and bottom surfaces of a silicon wafer.

The plasma etching apparatus of the present invention includes a reaction chamber and a vacuum exhaust port that can create a vacuum atmosphere isolated from the outside, and in the reaction chamber, slots and wafers for entering and exiting a wafer transfer mechanism for mounting or detaching a wafer. Up and down mechanism mechanism that can support the wafer without slipping with the rear surface of the wafer without slip, wafer alignment pin to accurately position the wafer, etching gas inlet located above the reaction chamber, inside the reaction chamber or Plasma source which is located outside and converts the etching gas into a plasma state, and a ground shield for maintaining a predetermined gap with the wafer to prevent plasma from penetrating the upper surface of the wafer An etching apparatus is disclosed.

Description

Plasma Etching Apparatus for Simultaneously Etching the Edge, Side, and Bottom of a Silicon Wafer {Plasma Etching Apparatus for Simultaneous Etching of Edge, Bevel and Back-side of Silicon Wafer}

The present invention relates to a plasma etching apparatus for simultaneously etching the edge, side, and bottom surface of a silicon wafer, and more particularly, plasma etching for performing etching in all regions except the upper surface portion of the silicon wafer in which the integrated circuit is formed. Relates to a device.

In order to form an integrated circuit on the upper surface of the silicon wafer, unit processes such as a thin film deposition process, a photo-drawing process, an etching process, and a cleaning process are performed collectively or repeatedly. Particles generated during the batch process are factors that directly affect the yield of the semiconductor device and are repeatedly removed mainly through a cleaning process.

The cleaning process is mainly performed by wet cleaning by dipping and stirring particles in a solvent or ultrapure water to remove particles. However, since the cleaning process apparatus fixes the side or bottom surface of the silicon wafer by physical contact, the thin film deposited on the silicon wafer during the cleaning process is fixed. There is a problem that can be detached from this side or bottom surface. In other words, the thin film deposited on the side or the bottom of the silicon wafer is desorbed during the wet cleaning process and remains as particles on the top surface of the silicon wafer, which causes a decrease in the yield of the semiconductor device.

Thin films deposited on the edge, side, and bottom of the silicon wafer become internal factors that can generate particles due to mechanical contact or thermal stress during wafer processing as well as the wet cleaning process. .

The present invention discloses a plasma etching apparatus for etching thin films in all regions of the silicon wafer except portions in which integrated circuits are formed in order to fundamentally remove particles generated from thin films deposited on a silicon wafer.

In order to simultaneously expose the plasma to only the edge, side, and bottom of the silicon wafer, a reaction chamber and a vacuum exhaust port are formed to create a vacuum atmosphere isolated from the outside, and the reaction chamber is provided for mounting or detaching the wafer. Slot for entering and exiting the wafer transfer mechanism, a vertical movement mechanism for supporting the wafer without slipping with a minimum contact area of the wafer, a wafer alignment pin for accurately positioning the wafer, and an upper portion of the reaction chamber. Plasma source which is located inside or outside the etching gas inlet, the lower part of the reaction chamber to convert the etching gas into the plasma state, and maintains a predetermined gap with the wafer to prevent plasma from penetrating into the upper surface of the wafer. Plasma provided with a ground shield An etching apparatus is disclosed.

A plan view of the silicon wafer 1 on which the thin film 3 to be etched by the plasma etching apparatus according to the present invention is deposited is shown in FIG. 1A. In the upper surface 4 of the silicon wafer on which the integrated circuit portion 2 is formed, a portion where the integrated circuit is not formed is an edge (Figs. 1B and 6). Typically, a 1.5 mm area from the side surface 7 toward the center of the wafer corresponds to the edges (Figs. 1B and 6).

A side view of the silicon wafer 1 on which the thin film 3 during the integrated circuit fabrication process is deposited is shown in FIG. 1B. The etch site 5 comprises an edge 6, a side 7 and a bottom face 8. By removing the thin films of all parts except the thin film on which the integrated circuit portion 2 of the upper surface 4 is formed, the generation of particles in the subsequent process is fundamentally removed.

In order to fundamentally remove particles generated from the thin film deposited on the silicon wafer 1, a plasma etching apparatus for etching the thin film in all regions except the portion where the integrated circuit portion is formed in the silicon wafer is shown in FIG. .

In order to simultaneously expose the plasma region 29 to only the edge 6, the side surface 7, and the lower surface 8 of the silicon wafer 1, the reaction chamber 9 may create a vacuum atmosphere isolated from the outside. A vacuum exhaust port 19 is provided, and in the reaction chamber 9, a slot 12 for entering and exiting a wafer mounting robot arm for mounting or detaching a silicon wafer, a lower surface 8 of a silicon wafer, and at least A vertical movement mechanism 13 capable of supporting the silicon wafer without slipping, a wafer alignment support 17 for accurately positioning the silicon wafer, and a gas injection hole located in the upper reaction chamber 10 ( 18) to prevent the plasma from penetrating into the plasma source 21 and the upper surface 4 of the silicon wafer which can be located inside or outside the lower reaction chamber 11 to convert the etching gas into the plasma state. To this end, a plasma etching apparatus is provided, which comprises a silicon wafer and a ground shield 20 holding a predetermined gap G.

The reaction chamber 9 is composed of an upper reaction chamber 10 and a lower reaction chamber 11 made of aluminum subjected to surface oxidation, and are vacuum sealed by a rubber ring 25.

A vacuum pump is connected to the vacuum exhaust port 19 to form an internal vacuum atmosphere of the reaction chamber 9. The connection of the vacuum pump for the vacuum vent 19 is not shown in this figure as the contents can be easily understood by those skilled in the art.

The reaction chamber 9 is provided with a slot 12 for accessing the wafer mounting robot arm for mounting or detaching the silicon wafer. The wafer mounting robot arm is a mechanism for transferring the silicon wafer from the outside of the reaction chamber into the reaction chamber and is not shown in the drawings as easily understood by those skilled in the art. The slot door 26 of the slot 12 is open while the wafer mounting robot arm enters into the reaction chamber 9 and is closed during vacuum evacuation or during plasma etching. The slot 12 is normally opened and closed by a pneumatic valve. The opening and closing of the slot by the pneumatic valve is not shown in the drawing as easily understood by those skilled in the art.

The vertical movement mechanism 13 which can support the silicon wafer without slipping with a minimum contact area of the lower surface 8 of the silicon wafer 1 includes an insulating support 15, an anti-slip support 16, and a vacuum bellows. It consists of. The anti-slip support 16 is attached to the end of the insulating support 15 made of Vespel material, and serves to support the lower surface 8 of the silicon wafer 1 without slipping. In order to support the silicon wafer, it is preferable to use three or four insulating supports 15. The insulated support 15 is connected to the up-and-down movement mechanism part 13, and the insulated support 15 also moves up and down according to the up-and-down movement of the up-and-down movement mechanism part 13 ,. The vertical movement of the vertical movement mechanism part 13 is normally operated by a pneumatic cylinder. The connection and operation of the pneumatic cylinder is not shown in the drawings as easily understood by those skilled in the art.

A wafer alignment support 17 that accurately positions the silicon wafer 1 is attached to the side wall of the lower reaction chamber 11. If the insulating support is raised while the silicon wafer is placed on the non-slip support 16 at the end of the insulating support 15, the wafer alignment support 17 is moved to the side of the silicon wafer to adjust the relative position of the silicon wafer and the support. do. It is preferable to use three wafer alignment supports 17 for the alignment of the silicon wafers.

The gas inlet 18 is located in the upper reaction chamber 10. The etching gas flowing from the gas inlet 18 is exhausted to the vacuum exhaust port 19 through the space between the side surface 7 of the silicon wafer 1 and the ground shield 20. In order to uniformize the flow of the etching gas, it is preferable to use the gas inlet 18 in the form of a shower ring. The showering form is not easily shown in the drawings as will be readily understood by those of ordinary skill in the art.

The plasma source 21 is composed of an antenna coil 22 and a high frequency power source 23. The antenna coil 22 is located inside or outside the lower reaction chamber 11. When the antenna coil 22 is mounted outside the lower reaction chamber 11, the high frequency power radiated from the antenna coil 22 propagates into the reaction chamber 9 through the ceramic 24 window. The etching gas in the reaction chamber 9 is converted into a plasma state. The plasma source 21 may be any electrodeless high-density plasma such as TCP (Transformer Coupled Plasma), ICP (Inductively Coupled Plasma), Helicon Plasma, Toroidal Plasma, or the like.

3 illustrates a case where the antenna coil 22 is mounted inside the lower reaction chamber 11. In this case, no ceramic (Fig. 2, 24) window is necessary.

The plasma source 21 forms a plasma composed of a plurality of electrons, a plurality of ions and a plurality of radicals in the reaction chamber 9, and the thin film is etched by the ions or radicals.

In order to prevent the plasma formed by the plasma source 21 from penetrating into the upper surface 4 of the silicon wafer 1, a ground shield 20 is provided to maintain a gap between the silicon wafer and the plasma sheath. . The plasma sheath is a length corresponding to several times the Debye Length, and has a range of 0.1 to 2 mm in the case of the present high density plasma source.

4 illustrates an etching region of the silicon wafer and the plasma region in the vicinity of the silicon wafer. In the plasma etching apparatus described above, the etching gas flows from the upper surface 4 of the silicon wafer 1 to the lower surface 8 through the side surface 7, and the plasma region 29 is lower than the silicon wafer 1. Produced on face 8 and diffused to top face 4 of the silicon wafer. On the side surface 7 of the silicon wafer, the ground shield 20 prevents the plasma from diffusing to the top surface 4 of the silicon wafer. Therefore, the thin film of all parts except the thin film 3 in which the integrated circuit portion 2 of the silicon wafer upper surface 4 is formed is in the plasma region in contact with the edge 6, the side surface 7, and the lower surface 8 of the wafer. It is etched by (29).

In order to more easily understand the configuration and operation of the plasma etching apparatus according to the present invention, the procedure of charging and etching the silicon wafer 1 and the operation sequence of the plasma etching apparatus will be described.

5, the vertical movement mechanism 13 descends, the slot door 26 is opened, and the silicon wafer 1 is mounted, in order to enter the silicon wafer 1 placed on the wafer mounting robot arm 27 in FIG. The mounting robot arm enters the reaction chamber 9.

In FIG. 6, when the sample mounting robot arm 27 enters the reaction chamber 9, the vertical movement mechanism 13 supporting the silicon wafer 1 is raised to adjust the height for plasma formation. .

In FIG. 7, when the vertical movement mechanism 13 supporting the silicon wafer 1 rises and the height adjustment is completed, the wafer alignment support 17 enters the reaction chamber 9 to align the left and right alignment of the silicon wafer 1. Will be

8 is a schematic diagram showing a state in which the silicon wafer 1 has completed the top, bottom, left and right position adjustment for forming the high density plasma. In order to form a high density plasma, the reaction gas is injected into the gas injection port 18, and the process pressure is adjusted in the range of several mTorr to several Torr. Dry etching is performed by forming the plasma region 29 on the edge 6, the side surface 7, and the lower surface 8 of the silicon wafer 1.

In FIG. 9, the wafer is aligned to dry etch the masked thin film 3 of the non-slip support 16 having a minimum contact area on the lower surface 8 of the non-dry-etched silicon wafer 1 in FIG. 8. The support 17 reenters the reaction chamber 9 to support the silicon wafer 1, and the vertical movement mechanism 13 is lowered to expose the covered thin film of the anti-slip support 16 to the plasma region 29. The bottom surface 8 of the silicon wafer 1 is completely dry etched.

By performing the above-described process, dry etching of the edge 6, the side surface 7, and the lower surface 8 of the silicon wafer 1, which is unnecessary for the semiconductor device, can be effectively etched.

The plasma etching apparatus according to the present invention provides a means for essentially removing particles generated from the thin film deposited on the silicon wafer by etching the thin film in all regions except the portion where the integrated circuit is formed in the silicon wafer.

1A is a plan view of a silicon wafer with integrated circuits formed thereon;

1B is a side view of a silicon wafer with a thin film deposited thereon

Figure 2 is a schematic diagram of a plasma etching apparatus for etching the edge, side, bottom surface of the silicon wafer of the present invention

3 is a schematic view of a plasma etching apparatus in which the plasma source of the present invention is located inside the reaction chamber;

FIG. 4 illustrates an embodiment of an etching region of a plasma region and a silicon wafer in the vicinity of the silicon wafer of the present invention.

Figure 5 is an embodiment of the robot arm entry for wafer transfer for mounting the silicon wafer of the present invention

Figure 6 is an embodiment of the rise of the moving mechanism for adjusting the height of the silicon wafer of the present invention

Figure 7 is an embodiment of the wafer alignment after removal of the robot arm for transferring the silicon wafer of the present invention

8 illustrates an embodiment in which a plasma region is formed after the silicon wafer positioning of the present invention is completed to remove the support.

Figure 9 is an embodiment of the wafer alignment support enters and descends the vertical movement mechanism to etch the remaining thin film of the minimum contact portion of the lower surface of the silicon wafer of the present invention

<Explanation of symbols for main parts of drawing>

1. Silicon Wafer 2. Integrated Circuit

3. Thin film 4. Top surface

5. Etch Area 6. Edge

7. Side 8. Bottom View

9. Reaction chamber 10. Upper reaction chamber

11.Reaction chamber below 12.Slot

13. Up and down moving mechanism part 14. Support plate

15. Insulation support 16. Non-slip support

17. Wafer alignment support 18. Gas inlet

19. Vacuum vent 20. Ground shield

21. Plasma Source 22. Antenna Coil

23. High frequency power supply 24. Ceramic

25.Rubber ring 26.Slot door

27. Robot arm for wafer mounting 28. Wafer fixing part

29. Plasma region

Claims (7)

In the plasma etching apparatus having a reaction chamber and a vacuum exhaust port to create a vacuum atmosphere isolated from the outside, A vertical movement mechanism part capable of supporting the wafer without slipping with a minimum contact area with the lower surface of the wafer, Wafer alignment support to accurately position the wafer, Etch gas inlet located above the reaction chamber, A plasma source capable of converting the etching gas into a plasma state in a lower reaction chamber; Plasma etching apparatus comprising a ground shield for maintaining a predetermined gap with the wafer to prevent plasma from penetrating the upper surface of the silicon wafer The plasma etching apparatus of claim 1, wherein a Vespel is provided at the pin end of the insulating support of the vertical movement mechanism. The plasma etching apparatus of claim 1, wherein the plasma source is provided outside the lower reaction chamber. The plasma etching apparatus of claim 1, wherein the plasma source is provided in the lower reaction chamber. The plasma etching apparatus of claim 3 or 4, wherein a high density plasma source of an electrodeless type is provided. The plasma etching apparatus of claim 1, further comprising an etching gas inlet having a showering shape. The plasma etching apparatus of claim 1, further comprising a ground shield that maintains a gap between the side of the wafer and 0.1 mm to 2 mm to prevent the plasma from diffusing to the upper surface of the wafer.