JPH0582478A - Etching method and device of wafer end - Google Patents

Abstract

PURPOSE:To provide the title etching method and device of wafer end capable of easily and completely removing the thin film only on the required position of an end using no etchant at all and without affecting the required thin film at all during the removal step of the thin film etc., of the end for avoiding the particle production from the wafer end. CONSTITUTION:A semiconductor wafer is held by a pair of upper and lower holders 2, 3 so that both main surfaces of the wafer may be covered with the holders 2, 3 while the specific circumferential ends protruded from the disc members 2, 3 may be exposed in the circumferential reaction chamber 21. On the other hand, when Ar or He gas is fed to a circumferential discharge part 11 to be impressed with high-frequency voltage while grow plasma is excited at atmospheric pressure to be activated, the Ar or He gas is turned into an etching gas to be led into the circumferential reaction chamber 21 for acting on the thin film etc., on the circumferential end so that the thin film may be removed by specific etching step to be exhausted together with an exhaust gas.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wafer end face etching method and apparatus for reducing particles adhering to a wafer in a process for obtaining various devices applied to a semiconductor wafer such as a silicon wafer. , The etching gas activated by glow plasma excitation of fluorine compound gas under atmospheric pressure completely removes the insulating material and metal deposited or adhered to the end surface of the wafer, and the contact of the end surface in the process TECHNICAL FIELD The present invention relates to a method and an apparatus for etching a wafer end face capable of preventing dust generation due to dust.

[0002]

2. Description of the Related Art Today's semiconductor integrated circuits are remarkably increased in density, and those manufactured by patterning of 1 μm or less have already been put into practical use. The size of particles adhering to a semiconductor wafer used as a substrate and the size thereof The number greatly affects the manufacturing yield.

Defects in various devices are generated even with particles having a size of about 1/10 of the minimum patterning width, so that a pattern of 1 μm or less is 0.1 μm.
The cleanliness of air and water is improved so that some particles do not adhere.

In addition, since various devices today have a multi-layer wiring structure adopted in accordance with high integration, semiconductors such as polysilicon, insulating materials such as silicon nitride, metal films such as aluminum and tungsten are also formed on the end faces of the wafer. , Resist, etc. are laminated.

However, in such a process, since the semiconductor wafer is repeatedly subjected to polishing, film formation, etc., the carrier case, a jig, etc. are brought into contact with the wafer end surface, and various thin films laminated on the end surface are peeled off to generate particles. Then, this adhered and caused a defect.

[0006]

Therefore, in order to prevent the generation of particles from the end face of the wafer, the thin film or the like on the end face is removed, but both are immersed in an etching solution for etching. Further, a method of grinding in liquid (Japanese Patent Laid-Open No. 63-307200, Japanese Laid-Open Patent Publication No.
No. 100319, JP-A No. 2-114529).

In order to perform the etching by immersing in the etching solution, only the required end face is exposed and the other portion is masked or the required protective film is provided. Therefore, there is a problem that it cannot be carried out at any time during the process, and even if masking is applied, the necessary multilayer film is peeled off due to the erosion effect of the etching solution and the liquid remaining at the interface due to the erosion. there were.

According to the present invention, when removing a thin film or the like on the end face to prevent the generation of particles from the end face of the wafer, it is possible to easily and completely remove only the thin film on a required part of the end face without using an etching solution. It is an object of the present invention to provide an etching method and an etching apparatus for a wafer end surface which does not affect the necessary thin film portion.

[0009]

According to the present invention, a fluorine compound gas is introduced into a discharge part by a carrier gas of an inert gas to excite glow plasma near atmospheric pressure, and an activated etching gas is used as a semiconductor wafer. The method for etching a wafer end surface is characterized in that the wafer is transferred to a required end surface portion and etched.

Further, according to the present invention, a chucking means for covering and supporting both main surfaces of a semiconductor wafer to expose a required circumferential end surface into a circumferential reaction chamber, and a ring-shaped quartz plate through a required discharge gap. And a glow plasma generating means near the atmospheric pressure, which is composed of a circumferential discharge chamber connected to a power source with electrodes provided on the back side of the circumferential discharge chamber and a carrier of a fluorine compound gas and an inert gas from the outer circumferential side of the circumferential discharge chamber. It is characterized by comprising a gas supply / exhaust means for supplying a gas, transferring the etching gas activated by exciting the glow plasma to the ring-shaped reaction chamber, and contacting the end face of the wafer in the reaction chamber and then exhausting the gas. This is an etching device for the end face of a wafer.

Further, the present invention requires a chucking means for covering and supporting both main surfaces of the semiconductor wafer to expose a required circumferential end surface into the circumferential reaction chamber, and a chucking means between the inner tube and the outer tube made of quartz. Near-atmospheric pressure glow plasma generating means consisting of a cylindrical discharge chamber connected to a power source by providing electrodes on the inner peripheral surface of the inner tube and the outer peripheral surface of the outer tube with a discharge gap passage, and from one side of the cylindrical discharge chamber Fluorine compound gas and carrier gas of inert gas are supplied, the etching gas activated by exciting glow plasma is transferred to the ring-shaped reaction chamber, and the gas is exhausted after contacting with the wafer end face in the reaction chamber and then exhausted. And a means for etching a wafer end face.

[0012]

The present invention uses an etching gas in which a fluorine compound gas is supplied as a carrier gas of an inert gas, quartz materials are arranged to face each other, and glow plasma is excited and activated in a discharge chamber capable of applying a required power source. Characterized in that the etching gas is applied to the required circumferential end surface of the semiconductor wafer that is chucked and exposed to remove a single-layer or multi-layer film made of various materials formed in the same portion. As compared with the conventional film removal using the etching solution, the etching solution does not remain, and the unnecessary film can be reliably removed without affecting the necessary thin film part.

In a preferred embodiment of the present invention, the discharge part has a structure in which a single or a plurality of discharge spaces are formed between a high-voltage electrode and a ground electrode, each of which has a dielectric material coated or opposed to the electrode surface. A discharge device having any known configuration can be used. For example, the electrode shape may be parallel facing, circumferential facing, or the like at equal intervals, and ceramics, enamel, glass, mica, etc. can be used as the dielectric material, but as shown in the examples, it is difficult to etch and particles are used. It is desirable to use a ring-shaped or cylindrical high-purity quartz material that does not generate a large amount of gas, a discharge space gap of 0.5 mm to 15 mm is desirable, and an increase in gas amount may be dealt with by stacking counter electrodes.

Further, as shown in the embodiment, a conductive mesh electrode made of a conductive material such as a wire mesh or carbon fiber, a metal foil, a conductive paste or the like is used for contacting with a dielectric quartz tube or the like. Therefore, it is desirable to cool the discharge part, for example, by cooling the dielectric with a copper tube in which cooling water is passed through the power supply wiring.

The power supply required for the glow plasma excitation is performed by applying a high voltage, and the AC voltage to be applied is for inducing an alternating voltage on the dielectric, which is from several tens Hz to GH.
A high frequency voltage of z level can be used and is appropriately selected depending on the discharge space and gas, but a range of 1 to 10 kV, a commercial frequency to 30 GHz, and 10 W to several kW are preferable,
Particularly, it is desirable to use RF (13.56 MHz) and high frequency of 10 kHz.

A fluorine compound gas such as CF ₄ or SF ₆ is used as a gas for exciting and activating the glow plasma.
As the carrier gas, a simple substance or a mixture of inert gases such as He, Ne and Ar can be appropriately used, and the mixing ratio of the fluorine compound gas and the carrier gas is required within a range capable of maintaining stable glow discharge near atmospheric pressure. It is appropriately selected according to the etching ability to be performed. Further, in this invention,
The term “atmospheric pressure” means an atmosphere under atmospheric pressure, weak decompression, or pressurization, which is an atmosphere capable of glow discharge, for example, 4
The activated etching gas can be obtained even under a slight reduced pressure of around 00 Torr or under a few atmospheres.

In the etching apparatus of the present invention, the chucking means for the semiconductor wafer has any structure as long as it can cover and support both main surfaces of the semiconductor wafer to expose the required circumferential end faces in the circumferential reaction chamber. Can also be adopted,
For example, by sandwiching a semiconductor wafer with a disk member in which an O-ring packing having a required radius is arranged on the circumference, and flowing an inert purge gas into the inside, it is possible to etch only the exposed circumference end face portion. It is also possible to adsorb one surface side under reduced pressure in the configuration.

In the etching apparatus of the present invention, the near-atmospheric pressure glow plasma generating means has the above-mentioned configuration of each part, and a required discharge gap passage is provided between quartz dielectrics, and an electrode is provided in each dielectric to provide a power supply part. A discharge chamber having a circumferential shape or a cylindrical shape, which is connected to the chamber and is arranged so as to be able to communicate with the circumferential reaction chamber, is preferable.

Further, in the etching apparatus of the present invention, the gas supply / exhaust means supplies the fluorine compound gas and the carrier gas from one side of the discharge chamber to excite glow plasma to activate the etching gas into the reaction chamber. Transfer
As long as it is a passage structure that can be exhausted to a required exhaust tank after contacting the wafer end surface in the reaction chamber, a pressure feeding system, a decompression suction system, or a combination of these systems can be used depending on the structure of the apparatus and the arrangement of each part. Selected.

[0020]

EXAMPLES Example 1 The etching apparatus shown in FIGS. 1 and 2 is an example in which a circumferential type near-atmospheric pressure glow plasma generator is mounted. The circumferential etching apparatus 1 is arranged between the upper and lower holders 2 and 3 of the chucking means, the circumferential discharge portion 11 which is provided around the chucks 4 and 5 via the cup-shaped frames 4 and 5, and each of these members. It is composed of a supply and exhaust passage.

The upper and lower holders 2 and 3 of the chucking means for sandwiching the semiconductor wafer 10 are made of disc members in which O-ring packings 6 and 7 made of fluororesin are arranged on the outermost peripheral circles and face each other. Through holes 8 and 9 are provided, the through hole 9 of the lower holder 3 is connected to the decompression pump VP to adsorb the semiconductor wafer 10, and the through hole 8 of the upper holder 2 is connected to the N ₂ gas pipe to connect the semiconductor wafer. 10
The surface is purged with N ₂ gas.

The upper and lower holders 2 and 3 are detachably screwed to the central hole portions of the cup-shaped frames 4 and 5, respectively, and the inner peripheral end portions of the upper and lower holders 2 and 3 and the cup-shaped frames 4 and 5 are attached. The ring members 12 and 13 forming the circumferential discharge portion 11 are arranged to face each other in between, and are bolted to the cup-shaped frames 4 and 5, respectively. Circumferential grooves are provided on the opposing surfaces of the ring members 12 and 13, and the copper pipe 1
4 and 15 are built in, and ring-shaped dielectrics 16 and 17 made of a quartz plate are fixed to the opposite surfaces via packing. The copper tubes 14 and 15 are R. It is connected to the F unit, a high frequency voltage of 13.56 MHz is applied, and cooling water is introduced into and out of the pipe by a cooling water pipe 20, as shown in FIG. 17 is a conductive paste 1 applied to a dielectric
8 and the metal foil 19 make an electrical connection. Therefore, the R.P. A circular discharge part 11 is formed by the ring-shaped dielectrics 16 and 17 to which the power of the F unit is applied.

The reaction gas is supplied to the circumferential discharge section 11 from the outer circumferential side of the circumferential discharge section 11 to the inner circumferential side by using the groove provided in the ring member 13 and the cup-shaped frame 5 as a supply path.
By the sealing member fixed to the outer peripheral portion of the upper holder 2, the lower ring member 13, the lower holder 3, the cup-shaped frame 5
After passing through the reaction chamber 21 formed on each outer peripheral surface of the above, it is led out to the gas scrubber 50 through the exhaust hole 22 provided in the lower holder 3.

The semiconductor wafer 10 has upper and lower holders 2, 3
Is supported by being sandwiched between, and both main surfaces thereof are covered, and a required circumferential end surface projecting from the disk member is exposed in the circumferential reaction chamber 21. For example, by supplying CF ₄ gas to the circumferential discharge unit 11 using Ar or He gas as a carrier gas and applying a high frequency voltage, the glow plasma is excited and activated at atmospheric pressure to become an etching gas and become a circumferential shape. It enters the reaction chamber 21, acts on the exposed circumferential end surface of the semiconductor wafer 10 to perform the required etching, and the film and the like on the end surface are removed and discharged together with the exhaust gas.

Embodiment 2 The etching apparatus shown in FIGS. 4 and 5 is an example in which a cylindrical near-atmospheric pressure glow plasma generator is mounted. A lower holder 32, which constitutes a chucking device for the semiconductor wafer 10, is fixed to the center leg 31 and the plate member at the center of a device frame 30 that supports four members by standing four legs between the plate members. The disk-shaped upper holder 33, which is paired with the lower holder 32, is fixed to a plate member which is vertically movable with four legs as guides.

The lower holder 32 includes a disk-shaped central portion 35 on which the O-ring packing 34 is arranged on the outer peripheral side and the semiconductor wafer 10 is mounted, and a ring-shaped outer peripheral portion 36 which is arranged with a gap therebetween. The upper surface of the void forms a reaction chamber 37 having a circular shape, and the central portion 35 and the outer peripheral portion 36 form a gas supply passage 38 that communicates with the reaction chamber 37. Through-hole 3 connected to vacuum pump VP for suction for mounting wafer 10 and adsorbing it
9 is provided. The lower holder 32 has a reaction chamber 34
A gas exhaust hole 40 communicating with the above is provided.

The upper holder 33 is provided with a recess 41 having a shape similar to that of the semiconductor wafer 10, the inner peripheral end face is provided with a packing 42, and the main wafer except the circumferential end face of the semiconductor wafer 10 placed on the lower holder 32 is provided. It is configured to supply N ₂ gas for purging to the surface.

An inner tube 4 made of quartz is provided on the lower surface of the lower holder 32.
3, an outer pipe 45 is coaxially arranged via an insulating member 44, the inner space of the inner pipe 43 and the outer pipe 45 communicate with the circumferential space and the gas supply passage 38, and the outer pipe 45 has a lower end side. It is connected to the reaction gas supply pipe 46. On the inner peripheral surface of the inner tube 43, an electrode 48 made of a conductive paste and an electrode 47 made of a wire mesh are formed.
And an electrode 48 made of a conductive paste is provided on the outer peripheral surface of the outer tube 45. It is connected to the F unit. Therefore, the inner tube 43 made of a quartz dielectric and the outer tubes 4 and 5 are coaxially arranged, a required discharge gap is formed between the tubes, and a reaction gas is supplied to the electrodes 47 and 48 between the tubes. A cylindrical discharge portion 49 to which a high frequency power source can be applied is formed.

After placing the semiconductor wafer 10 on the lower holder 32 to adsorb it, and further placing the upper holder 33 thereon, the reaction gas supply pipe 46 is connected to the cylindrical discharge part 49 from the reaction gas supply pipe 46, for example.
When F ₄ gas is supplied as Ar or He gas as a carrier gas and a high frequency voltage is applied, glow plasma is excited and activated at atmospheric pressure, and this rises as an etching gas to expose the semiconductor wafer 10 in the reaction chamber 37. By performing the required etching by acting on the circumferential end surface of
The film or the like on the end face is removed and discharged together with the exhaust gas.

[0030]

According to the present invention, since the etching gas activated by glow plasma excitation of fluorine compound gas under atmospheric pressure can completely remove the insulating material or metal deposited or attached to the end face of the wafer. It is possible to prevent dust generation due to contact of the end face portion in the process. Compared with the conventional method of removing the film on the end face of the wafer by immersing it in an etching solution, the etching power is stronger and there is no excessive etching due to the remaining etching solution, and it can be performed at any step of the device process. Therefore, it is extremely advantageous for preventing dust generation on the semiconductor wafer.

[Brief description of drawings]

FIG. 1 is a vertical cross sectional view showing the structure of a circumferential etching apparatus according to the present invention.

FIG. 2 is a partially cutaway perspective view showing the structure of the discharge part of the circumferential etching apparatus according to the present invention.

FIG. 3 is a block diagram showing a gas supply / exhaust configuration of the circumferential etching apparatus according to the present invention.

FIG. 4 is a perspective explanatory view showing a configuration of a cylindrical etching apparatus according to the present invention.

FIG. 5 is a vertical cross-sectional explanatory view showing a configuration of a main part of a cylindrical etching apparatus according to the present invention.

[Explanation of symbols]

 1 Circular etching device 2 Upper holder 3 Lower holder 4,5 Cup-shaped frame 6,7 O-ring packing 8,9 Through hole 10 Semiconductor wafer 11 Circular discharge part 12,13 Ring member 14,15 Copper tube 16, 17 Ring Dielectric 18 Conductive Paste 19 Metal Foil 20 Cooling Water Pipe 21 Reaction Chamber 22 Exhaust Hole 30 Device Frame 31 Center Leg 32 Lower Holder 33 Upper Holder 34 O-Ring Packing 35 Center 36 Peripheral 37 Reaction Chamber 38 Gas Supply passage 39 Through hole 40 Gas exhaust hole 41 Recessed portion 42 Packing 43 Inner tube 44 Insulating member 45 Outer tube 46 Reactive gas supply tube 47, 48 Electrode 49 Cylindrical discharge part 50 Gas scrubber

Claims (3)

[Claims] 1. A fluorine compound gas is introduced into a discharge part by a carrier gas of an inert gas to excite glow plasma near atmospheric pressure, and the activated etching gas is transferred to a required end face part of a semiconductor wafer for etching. A method for etching a wafer end face, comprising: 2. A chucking means for covering and supporting both main surfaces of a semiconductor wafer to expose a required circumferential end face into a circumferential reaction chamber, and a ring-shaped quartz plate are arranged to face each other via a required discharge gap. Glow plasma generating means near the atmospheric pressure consisting of a circumferential discharge chamber connected to a power source by providing an electrode on each back side, and a fluorine compound gas and a carrier gas of an inert gas are supplied from the outer circumferential side of the circumferential discharge chamber. , An etching gas that is activated by activating glow plasma and transferred to a ring-shaped reaction chamber, and supplies and exhausts a gas that is exhausted after contacting the wafer end surface in the reaction chamber and etching the wafer end surface. apparatus. 3. A chucking means for covering and supporting both main surfaces of a semiconductor wafer to expose a required circumferential end surface into a circumferential reaction chamber, and a required discharge gap passage between a quartz inner tube and an outer tube. Glow plasma generating means near the atmospheric pressure consisting of a cylindrical discharge chamber provided with electrodes on the inner peripheral surface of the inner tube and an outer peripheral surface of the outer tube and connected to a power source, and a fluorine compound gas from one side of the cylindrical discharge chamber. The carrier gas of the inert gas is supplied, and the etching gas activated by exciting the glow plasma is transferred to the ring-shaped reaction chamber, and the gas is supplied and exhausted after being brought into contact with the end face of the wafer in the reaction chamber and then exhausted. A wafer end face etching apparatus characterized by the above.