JPH01306583A - Reactive ion etching device - Google Patents

Abstract

PURPOSE:To improve the uniformity of an etching rate and its yield by relatively rotating a material to be etched while paralleling the magnetic field direction and the material surface. CONSTITUTION:A material to be etched is placed on a rotor 42 through a material receiver 41 and an O ring 4, and chucked by chucks 3. An inert gas such as He is introduced from an inert gas inlet 5, and allowed to flow out from a gas orifice 6 inside the O ring 4 to fill the space between the material bottom and the upper surface of the rotor 42. Consequently, the heat produced on the material is radiated toward the cooled cathode. The rotor 42 is rotated by a motor set below the lower cathode 1, and the material is relatively rotated while paralleling the magnetic field direction and the material surface. The reactive ion etching device is appropriately used in the dry developing of a resist for dry development process.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an etching apparatus used in the manufacturing process of semiconductor devices such as ICs and LSIs, and more particularly to a reactive ion etching apparatus.

[Conventional technology] Conventionally, the manufacturing process of semiconductor devices such as IC5LSI involves the following steps:
On the substrate to be processed, there is a negative photoresist made by mixing polyisoprene cyclized product with bisazide, and a positive photoresist made by mixing novolac resin with a quinonediazide compound! A photolithography method is used in which a pattern is formed by coating a radiation-sensitive resin such as ・, exposing it to G-line (wavelength 436 ncn) or I-line (365 nm) from a mercury lamp, and developing it with a developer. ing.

However, in recent years, LSIs have become even more miniaturized, and the minimum dimension of a pattern to be formed on a substrate is entering the region of 1 μm or less. Even if it is used, especially when a substrate with a stepped structure is used, problems such as the effects of light reflection during exposure and the shallow depth of focus in the exposure system may cause problems such as insufficient resolution. do.

As a method to solve such problems, JP-A-61-1
No. 07346 discloses dry development in which a resist pattern is formed by developing by etching using a reactive ion etching device that generates gas plasma such as oxygen plasma, instead of developing using a developer in the photolithography method. A process is proposed.

As an example of this reactive ion etching device,
Publication No. 8-151028 and JP-A-59-14037
Publication No. 5 discloses a reactive ion etching method that develops a means for forming a magnetic field parallel to the surface of the material to be etched on a cathode that is a support for the material to be etched and to which microwave power is applied. The equipment is described.

[Problems to be Solved by the Invention] These reactive ion etching devices can increase the concentration of reactive species in the generated gas plasma. ] Etching can be performed at a higher speed than an i-plate type reactive ion etching apparatus.

On the other hand, however, these devices have the problem that it is difficult to maintain a uniform density of gas plasma, and that the etching rate is non-uniform depending on the portion of the material to be etched.

In particular, an etching barrier is formed by selectively diffusing an organic silicon compound into the resist pattern area as described in the multilayer resist process using a two-layer resist or a three-layer resist, and in the above-mentioned Japanese Patent Application Laid-Open No. 107346/1983. When using our reactive ion etching apparatus as a gas plasma dry development process, the etching speed of the part of the material to be etched, especially the area around the chuck of the material to be etched, is different. The problem is that the line width of the resist pattern is not controllable and the yield is low.

SUMMARY OF THE INVENTION An object of the present invention is to provide a reactive ion etching apparatus capable of solving the above-mentioned conventional problems and performing etching with excellent uniformity of etching rate and high yield.

[Means for Solving the Problems] In order to achieve the above object, the reactive ion etching apparatus of the present invention employs a reactive ion etching system having means for forming a magnetic field parallel to the surface of the material to be etched. The apparatus is characterized in that it includes means for relatively rotating the material to be etched while keeping the direction of the magnetic field parallel to the surface of the material to be etched.

The present invention will be explained below with reference to the drawings.

FIG. 1 is a perspective view of one example of the cathode of the reactive ion etching apparatus of the present invention. The cathode of this example is a non-magnetic material mounted on a rotating body 42 that is provided on the cathode lower plate 2 of the cathode 1 and rotates the material to be etched relatively while keeping the direction of the magnetic field parallel to the surface of the material to be etched. This cathode has a structure in which a material to be etched (not shown) is held and supported by a chuck 3 of the material to be etched, such as a silicon wafer.

The material to be etched is placed on the rotating body 42 via the material receiver 41 and the O-ring 4, and is held down by the chuck 3 for the material to be etched. The inert gas introduced from the inert gas port 5, such as helium gas, flows out from the gas outlet groove 6 inside the O-ring 4 via a rotating flange (not shown) and contacts the bottom surface of the material to be etched. It fills the space between the upper surface of the rotating body 42 and radiates the heat generated in the material-L to be etched to the cooled cathode side. In addition, the cathode 1 is heated to a temperature of 20° C. or less, preferably 0.0° C., by a refrigerant that flows into the cathode 1 from the refrigerant lower as needed, flows through a refrigerant gas passage (not shown) in the cathode upper plate 2, and is discharged from the refrigerant outlet 8. It can also be cooled to below .degree.

The rotating body 42 is rotated by a motor (not shown) installed under the lower cathode 1 .

Reference numeral 1 in FIG. 2 is a sectional view showing details of the cathode structure similar to the example of the cathode shown in FIG. 1, 22 is an auxiliary magnet, and FIG. 3 is a cross-sectional view thereof. A permanent magnet 10 is provided between the cathode upper plate 2 and the cathode lower plate 9, and pole pieces 11 and 12 made of a magnetic material are provided at both ends thereof, respectively.

Ground shields 15 and 16 are attached to insulators 13 and 14 fixed to pole pieces 11 and 12, respectively. A refrigerant gas passage 17 is usually provided in the cathode upper plate 2, and a refrigerant (for example, helium, nitrogen, or fluorinated refrigerant [such as Fluorinert manufactured by 3M Company]) is introduced from the refrigerant lower into the rotating body. 42, the material to be etched 18 can be cooled to a temperature below 20°C. In addition, in FIG. 2, an auxiliary magnet 22 for forming an auxiliary magnetic field consisting of a permanent magnet 19 and pole pieces 20 and 21 is provided above the cathode 1. By interaction with the magnet 22,
A magnetic field parallel to the surface of the material to be etched 18 is formed, as shown by magnetic lines of force 23 .

In addition, in FIG. 2, the rotating body 42 rotates while keeping the direction of the magnetic field parallel to the surface of the material to be etched, but the cathode 1
The etching device itself and the auxiliary magnet 22 may be rotated while keeping the direction of the magnetic field parallel to the surface of the material to be etched.

The surface of the chuck 3 for the material to be etched is preferably made of a material that is insulating and has excellent dry etching resistance in order to make the etching rate uniform around the chuck of the material to be etched. For example, it is preferably made of glass such as sodium glass, quartz glass, or cloud tJ, ceramics such as alumina, or metals such as molybdenum or tungsten.

Furthermore, an electrostatic chuck may be used to support the material to be etched. This electrostatic chuck has an electrode sandwiched between ferroelectric materials made of polymer materials such as polyimide and polyvinylidene fluoride, and ceramics such as alumina. It can be supported on the top plate.

FIG. 4 shows a schematic sectional view of a reactive ion etching apparatus according to the present invention. The cathode 1 shown in FIGS. 1 to 3 is installed in the reaction vessel 25, and the material to be etched 18 is supported thereon. Further, an anode 26 is placed opposite the cathode 1 . A terminal 27 connected to the cathode 1 is insulated from the reaction vessel 25 by an insulator 28, and by applying high frequency power between the anode 26 and the cathode 1 by a high frequency power supply 29, a reaction gas, which will be described later, is generated. A gas plasma is generated, and reactive species in the gas plasma contribute to etching. In this example, after the inside of the reaction container 25 is evacuated to a high vacuum by the mechanical pump 31 and the turbo pump 30, the reaction gas from the reaction gas container 32, or the inert gas from the inert gas container 33 together with the reaction gas, is The reactant gas is introduced into the reaction vessel 25 through the hole 26A provided in the cathode 1, and high frequency power is applied to the cathode 1 to generate plasma of the reaction gas, thereby etching the material to be etched.

Note that the hole 26A provided in this anode 26 usually has a hole diameter of 2.
It is 0 μm to 2 mm. Here, the flow rate of the reaction gas and the pressure inside the reaction vessel 25 are controlled by the flow rate control valves 34 and 35.
and a control valve 36.

The progress of etching of the material to be etched is detected by an etching detection device 37. In addition, in the apparatus of this example, a wafer cassette containing a plurality of materials to be etched (
After taking out one sheet of the material to be etched from (not shown) and loading it into the preparation chamber 38, the control valve 39 is opened.
It is also possible to evacuate the preparation chamber with the mechanical pump 31, open and close the gate valve 40, and automatically convert wafers to sequentially process a plurality of materials to be etched. Furthermore, in the preparation chamber 38, purging with heated nitrogen or heating with a heater is provided to prevent moisture in the atmosphere from condensing on the material to be etched when the cooled material to be etched returns to the atmosphere. Preferably, there is a means to do so.

In addition, in FIG. 4, illustration of the auxiliary magnet is omitted.

The conditions for etching a material to be etched using the reactive ion etching apparatus shown in FIG. 4 are generally as shown below.

Distance between cathode 1 and anode 26 3~20cm cathode 1
Applied power between the anode 26 and the anode 26: 10 W to 4 KW, preferably 100 W to 3 Kw Temperature of the cathode 1: 0°C or less, preferably 0°C or less Temperature of the material to be etched 18: 409C or less Magnetic field strength: 100 to 400 Gauss Reaction gas flow rate: 2 to 2008 CCM , preferably 2 to 100 SCCM Pressure during etching 1 to 100 mTorr, preferably 5 to 80 Torr Rotation speed of rotating body 0.5 to 30 rpm, preferably 1 to 10 pIII Reaction gas introduction method In Fig. 4, the reaction gas is introduced from the anode. However, it may be introduced from the reaction vessel 25 (side or both sides).

Reaction gas 02, N20. CF4, C2F6, C3F
Inert gas such as N2, He5Ar, etc. Materials to be etched by the reactive ion etching apparatus of the present invention include substrates such as glass, silicon wafers, gallium, arsenic, etc., on which a resist layer is provided. can.

This resist layer is made by irradiating a radiation-sensitive resin in which a part of a hydroxyl-based resin such as novolac resin or hydroxystyrene resin is esterified with quinonediazide sulfonyl halide, and then converting the irradiated portion to hexamethyldisilanzane or silyl. Selectively silylated with silane compounds such as chloride, quinonediazide positive resist, cyclized rubber negative resist, bisazide
Resist materials such as novolak resin-based negative resists,
Polymethyl methacrylate, polymethyl isopropenyl ketone, polybutene sulfone, poly-2-methyl-1-
"-layer, consisting of ionizing radiation-sensitive positive-tone resist materials such as pentyl sulfone/novolac resins, or ionizing radiation-sensitive negative-tone resist materials such as chlorinated polymethylstyrene, chloromethylated polystyrene, silicon ladder polymers, etc., Si02, Ti/ An intermediate layer (etching barrier) consisting of an inorganic film such as W, highly repellent polycondensation polymers such as polyimide and polyamideimide, (meth)acrylic polymers such as polymethyl methacrylate and polyphenylacrylate, quinone diazide positive resist, A three-layer film consisting of a lower layer made of a bisazide-novolak resin negative resist is irradiated with radiation and the upper layer is developed. ■ A resist material made of a quinone diazide photosensitizer or a bisazide photosensitizer and a silicon-containing polymer, and a haloalkyl group. A two-layer film consisting of an upper layer made of an ionizing radiation-sensitive negative resist material such as a silicon polymer or an inorganic resist material such as chalcogenide glass, and a lower layer similar to the lower layer of the three-layer film in (1) above, is irradiated with radiation. , the upper layer is developed.

[Example] Next, an example of etching using the reactive ion etching apparatus according to the present invention will be described.

Example 1 A silicon wafer with a diameter of 6 inches was coated with 6-diacy5,
A resist containing a partial esterification product of 6-sihydro-5-oxo-1-naphthalenesulfonic acid chloride and a novolak resin was applied using a spin cord and dried to form a resist layer.

The entire surface of the wafer is etched using a reactive ion etching apparatus having the configuration shown in FIG. 4, which includes a cathode shown in FIG. went. The etching conditions were as follows: distance between the cathode and anode was 7 cm, power applied between the cathode and anode was 1.5 KW, pressure was 2 to 3 Torr, magnetic field strength was 170 Gauss, cathode temperature was 18°C, oxygen was used as the reaction gas, and the flow rate was 308 CCM. was introduced through a hole in the anode. Also, the rotation speed of the rotating body is 5 rpm.
And so. As a result, the variation in the amount of reduction in the resist layer was within 2%, excluding the portion covered by the wafer chuck.

Comparative Example 1 Etching was performed on the entire surface of the wafer on which the resist layer was formed in the same manner as in Example 1 except that the silicon wafer having the resist layer was not rotated.

The variation in the amount of reduction in the resist layer was 5 to 7%.

Comparative Example 2 Except for Example 1, in which the wafer having a resist layer was not rotated and the wafer chuck was made of 5US316 and the cathode shown in FIG. 1 was heated, a reactive ion etching apparatus having the configuration shown in FIG. 4 was used. is the same as in Example 1,
Etching was performed on the entire surface of the wafer on which the resist layer was formed. The variation in the amount of decrease in the resist layer was 5 to 7%, and there was almost no decrease in the resist layer within 8 mm from the wafer chuck.

Example 2 A silicon wafer having a resist layer was prepared in the same manner as in Example 1, and ultraviolet rays were irradiated through a reticle using a g-line stepper with an aperture coefficient of 0.42.

Next, the silicon wafer was placed in a silylation apparatus having a stainless steel upper heating plate and a stainless steel lower heating plate each having a plurality of 50 μm pores, and silylated using hexamethyldisilazane.

The conditions for silylation are as follows: Full pressure cuff of the UV irradiated area.
The conditions were 60 mmHg, hexamethyldisilazane concentration of 6.6% by volume, and temperature of 140°C for 1 hour and 1 minute.

Subsequently, this silylated silicon wafer was used in Example 1.
Etching was performed in the same manner as above to form a resist pattern. The resist pattern of the obtained silicon wafer 1- was a line-and-space pattern with equal intervals of 0.5 μm, and the variation in line width was within 4%.

Comparative Example 3 A silicon wafer with a resist layer formed thereon was etched in the same manner as in Example 2, except that the silicon wafer with the resist layer was not rotated. The variation in line width of the obtained resist pattern is 10~
It was 15%.

[Effects of the Invention] As explained above, according to the reactive ion etching apparatus of the present invention, the material to be etched can be rotated, the etching rate is excellent in uniformity, and etching can be performed with a high yield. .

In particular, the reactive ion etching apparatus of the present invention is suitable as a dry developing apparatus for resists for dry developing processes.

[Brief explanation of the drawing]

1, 2, and 3 are respectively a perspective view, a sectional view, and a top view of an example of a cathode of a reactive ion etching apparatus according to the present invention, and FIG. 4 is an example of a reactive ion etching apparatus according to the present invention. FIG. 1...Cathode 2...Cathode top plate 3...Etched chuck 4...
...O-ring 5...Inert gas population 6...Gas outflow groove 7...Refrigerant population 8...Refrigerant outlet 9...・Cathode lower plate 10... Permanent magnet 11.12... Pole piece 13.14... Insulator 15.16... Ground shield 17... ... Refrigerant passage 18 ... Material to be etched 19 ... Permanent magnet 20.21 ... Pole piece 22 ... Auxiliary magnet 23 ...・Magnetic field lines 24... Electrostatic chuck 25... Reaction vessel 26... Anode 27... Terminal 28... Insulator 29. ...High frequency power supply 30 ...Turbo pump 31 ...Mechanical pump 32 ...Reaction gas container 33 ...Inert gas container 34.35. ...Flow control valve 36.39...
... Control valve 37 ... Etching detection device 38 ... Preparation chamber 40 ... Gate valve 41 ... Etched material receiver 42 ... ...Rotating body patent applicant: Japan Synthetic Rubber Co., Ltd.

Claims (1)

[Claims] (1) In a reactive ion etching apparatus that has means for forming a magnetic field parallel to the surface of the material to be etched, the material to be etched is held relative to the surface of the material to be etched while keeping the direction of the magnetic field parallel to the surface of the material to be etched. A reactive ion etching device characterized by comprising means for rotating the device.