KR0124512B1 - Apparatus and method for dry etching using light and microwave - Google Patents

Abstract

Disclosed is a dry etching apparatus using light and microwave including a plasma tube(37), a reaction chamber(33), and an investigation device(40). The plasma tube(37) inlet the gas activated by a microwave generation device to the reaction chamber in which a wafer(31) is positioned. The activated gas reacts the wafer(31) placing on a electrode(32) to which a supply voltage is applied in the reaction chamber(33). The surface of the wafer(31) is activated by vertically projecting light to the wafer(31) on the upper part of the chamber(33). Thereby, the investigation device(40) helps to react radical input into the chamber(33) through the plasma tube(37).

Description

Dry etching apparatus and etching method using surface activated energy source and microwave

1 is a cross-sectional view of a conventional magnetron enhanced reactive ion etching (MERIE) dry etching apparatus.

2 is a functional state diagram showing a polysilicon layer in an etching state using a conventional etching apparatus.

3 is a cross-sectional view of a dry etching apparatus using a microwave and a surface activated energy source according to an embodiment of the present invention.

Figure 4a is a functional state diagram showing a state of etching the polysilicon layer in a state where RF power is applied using the etching apparatus according to an embodiment of the present invention.

Figure 4b is a functional state diagram showing a state of etching the polysilicon layer in a state where RF power is not applied using a dry etching apparatus according to an embodiment of the present invention.

* Explanation of symbols for main parts of the drawings

1, 31: wafer 2, 3, 32: electrode

4: plasma 5, 47: pumping line

6, 33: chamber 7: ion sheath

8: ground shielding film 9, 34: chamber wall

10, 36: gas injection hole 11: electromagnet

12, 41: chamber coolant inlet 13, 42: chamber coolant outlet

14, 15: RF source 15, 46: blocking capacitor

16, 43: electrode coolant inlet 17, 44: electrode coolant outlet

21, 51: silicon substrate 22, 52: gate oxide film

23, 53 ': polysilicon pattern 24, 54: mask pattern

25, 55: ion 35: surface activated energy source

37: plasma tube 38: wave guide

39: quartz 40: irradiation device

53 polysilicon layer 56 radical

The present invention relates to an etching process in a semiconductor manufacturing process, and more particularly to a dry etching apparatus and an etching method using a surface active energy source and microwave.

The etching process is an essential process in the semiconductor manufacturing process. Conventional etching process mainly used a wet etching process technology, but as the device is increasingly integrated, recently, a dry etching process technology with less CD (CRITICAL DIMENSION) loss is used. Dry etching process has advantages such as providing high resolution and no undercut (UNDER CUT) compared to other types of etching process, in particular, has the advantage of enabling complete automation of the semiconductor manufacturing process.

Plasma is a highly ionized gaseous material containing the same number of cations and anions and free radicals. Ions are basically physically etched and radicals are chemically etched. In addition, radicals refer to atoms or molecules that are chemically activated and electrically neutral, and combine with a material to be etched to generate a volatile compound to perform etching. Plasma etching equipment is usually composed of plasma generating equipment, reaction chamber and exhaust system, and the basic conditions necessary for this etching equipment are high etching rate, anisotropic etching, less damage of silicon substrate by ion or electron collision, etc. Can be mentioned. In the case of normal ion etching, the ions generated in the plasma are accelerated by the electric field and are driven to the exposed surface of the silicon substrate, which is etched by the kinetic energy of this ion. And, the electric field is usually caught by an external electric field source.

The direction of motion of the ions is controlled by the electric field, resulting in anisotropic etching regardless of the gas pressure. In addition, high etch rates can be achieved with high acceleration potentials and high gas pressures. However, the relatively high energy damages the silicon substrate during the etching process. On the other hand, plasma etching by free radicals does not cause damage by sputtering, but unfortunately, since the radicals are not electrically charged, the direction in which the radicals collide with the silicon substrate cannot be controlled by an electric field. In addition, chemical etching using high gas pressure is not suitable for anisotropic etching since free radicals randomly move randomly and do not collide perpendicularly with the silicon substrate.

The conventional etching apparatus includes a RIE (REACTIVE ION ETCHING) method, a MERIE (MAGNETRON ENHANCED REACTIVE ION ETCHING) method, an ECR (ELECT RON CYCROTRON RESONANCE) method, and the like. Here, the RIE method is a method of injecting the etching gas into the chamber of a high vacuum state in which the wafer is present, and then etching the plasma by applying RF (RADIO FRQUENCY) power to the electrode on which the wafer is placed.

However, a certain level of RF power is required to form a certain level or more of the etcher, and due to the RF power applied there is a problem that damages the silicon substrate as described above.

Hereinafter, a conventional dry etching apparatus will be described with reference to FIGS. 1 and 2.

FIG. 1 is a cross-sectional view of a MERIE etching apparatus, and FIG. 2 shows an etching state diagram when etching using the etching apparatus of FIG.

As shown in FIG. 1, an etching apparatus manufactured by using a conventional MERIE method includes an etching gas injected into a chamber 6 in a high vacuum state in which a wafer 1 is placed, and then an electrode 2 on which the wafer 1 is placed. ) By applying RF power of several hundred W (watt) level to form plasma 4 in chamber 6 to form etching species, and to form magnetic field using electromagnet 11 to form chamber 6 By increasing the density of the plasma (4) by causing the collision of the etching gas in the plasma (4) within the method to form more etch species that can eventually react to obtain a high etching rate. The apparatus has two electrodes 2, 3 inside the chamber 6, and is pumped through the pumping line 5 by a pumping device (not shown) to maintain a high vacuum in the chamber 6. . The chamber wall (9) has a chamber coolant inlet (12) and a chamber coolant outlet (13) for cooling the flow of the coolant so that the chamber (6) can be maintained at a constant temperature. An RF source 14 for supplying RF power is connected to the electrode 2 on which the wafer 1 is placed through the blocking capacitor 15, and the electrode coolant inlet 16 for adjusting the wafer 1 to a predetermined temperature. Cooling water flows through the outlet 17. The ground shield 8 shields the plasma 4 and the electrode 2 to stabilize the plasma 4, and the electrode 2 and the chamber wall 9 on which the wafer 1 is placed are electrically Grounded to insulate. That is, when the wafer 1 is placed on the electrode 2, gas is injected from the upper electrode 3 into the chamber 6 through the gas injection hole 10, and at this time, the electrode 2 on which the wafer 1 is placed The RF power of 13.56 MHz is applied to several hundred watts (watts), and when the magnetic field is applied by the electromagnet 11 outside the chamber 6, the plasma 4 is generated inside the chamber 6. Since the plasma 4 is accelerated by the electric field formed in the ion sheath 7 and collides with the surface of the wafer 1, anisotropic etching is possible, but there is still a problem of damage to the silicon substrate due to ion sputtering.

FIG. 2 sequentially deposits the gate oxide layer 22 and the polysilicon layer 23 on the silicon substrate 21, forms the mask pattern 24, and then etches the same with the conventional etching apparatus MERIE as shown in FIG. When the etching is completed, the lower oxide film 22 is slightly damaged by the ions 25 after the etching is completed.

As a result, the conventional MERIE etching apparatus is a method of forming a plasma by using a magnetic field in the conventional RIE method, and can obtain a high plasma density at low pressure.

However, the conventional dry etching apparatus (RIE and MERIE) as described above has a problem that damage and loss of the lower oxide film occurs because a certain level or more RF power is required to form more than a certain level of etching species. . In addition, in the etching apparatus using microwaves designed to reduce damage to the silicon substrate, radicals are generated by using microwaves at high pressure, and the etching is performed by the radicals.

Therefore, the present invention devised to solve the above problems, by selectively irradiating the surface activation energy sources such as UV, LASER, X-RAY on the wafer to be etched to activate only the surface portion of the film to be etched, only in this region It is an object of the present invention to provide a dry etching apparatus and an etching method for causing anisotropic etching to be reacted with radicals and minimizing damage to an oxide layer under the polysilicon layer.

Dry etching apparatus of the present invention devised to achieve the above object comprises a plasma tube for introducing the gas activated by the microwave generator into the reaction chamber on which the wafer; A reaction chamber in which the activated gas enters and reacts with a wafer placed on an electrode to which RF power is applied; And irradiating a surface activation energy source vertically to the wafer at the upper end of the chamber to activate the surface of the wafer, thereby providing a surface activated energy source irradiation device which helps to react with radicals introduced into the chamber through the plasma tube. It is characterized by including the.

In the dry etching method of the present invention, when the wafer enters the chamber, RF power is applied to the electrode on which the wafer is placed to generate a plasma, and the etching target layer is etched using ions and radicals constituting the plasma. A first step of etching only the thickness of the wafer, preventing the RF power from being applied to the electrode on which the wafer is placed, allowing only radicals entering the chamber through the plasma tube to be present in the chamber, and simultaneously from above the wafer surface to the And a second step of irradiating surface activation energy so that the etching target layer reacts with the radical to be etched.

Hereinafter, with reference to the accompanying drawings will be described an embodiment of the present invention;

First, referring to FIG. 3, a dry etching apparatus using microwaves and surface activated energy sources (UV, LASER, X-RAY, etc.) devised by the present invention is largely activated by a gas generator (not shown). Surface activation energy sources (UV, LASER, X-RAY, etc.) are irradiated onto the plasma tube 37, the reaction chamber 33 that enters the gas to react with the wafer 31, and the wafer 31 during etching. Consists of the irradiation device 40 to help.

At the left and upper ends of the chamber 33, there is a gas inlet 36 through which gas is introduced, and microwaves generated from a microwave generator (not shown) are transmitted to the plasma tube 37 through the waveguide 38. The gas flowing from the gas inlet 36 receives microwaves to form an activated gas, and a plasma tube 37 for flowing out the activated gas is formed. At this time, the plasma tube 37 is formed of quartz to prevent the transmission of microwaves and the influx of contaminants. The upper end of the chamber 33 is irradiated into the chamber 33 through the plasma tube 37 by activating the surface of the wafer 31 by irradiating the surface activation energy source 35 perpendicular to the wafer 31 in the chamber 33. An irradiation apparatus 40 is formed to help cause a reaction with radicals, and a quartz plate 39 is formed between the irradiation apparatus and the chamber 33 so that the surface activated energy source 35 can pass therethrough.

In the chamber 33, an electrode 32 on which the wafer 31 can be placed is formed, and radicals activated by microwaves from the plasma tube 37 flow into the chamber 33 and at the same time the chamber 33 When the surface activation energy source 35 generated from the irradiation device 40 is irradiated onto the wafer 31 surface, the surface activation energy source 35 reacts with the wafer 31 on the electrode 32. In addition, the chamber wall 34 has a chamber cooling water inlet 41 and an outlet 42 formed in the same manner as a conventional etching apparatus to maintain a constant temperature of the chamber. In addition, the coolant flows through the coolant inlet 43 and the outlet 44 in order to adjust the wafer 31 to a predetermined temperature in the electrode 32, and a natural oxide film (not shown) is formed on the surface of the wafer 31. An RF source 45 for supplying 1 to 100 W (watts) of RF power was connected via the blocking capacitor 46 to the electrode 32 on which the wafer 31 is placed to assist in the etching and anisotropic etching of the etch. In addition, the pumping device (not shown) is configured to pump through the pumping line 47 to maintain a high vacuum in the chamber 33 as in the conventional etching apparatus.

Subsequently, an etching method using an etching apparatus according to an embodiment of the present invention will be described with reference to FIG. 3.

That is, when the wafer 31 is moved into the chamber 33 and placed on the electrode 32, gas enters through the gas inlet 36 and is activated by microwaves in the plasma tube 37 to generate radicals. It enters into the chamber 33. At this time, when the 13.31 MHz RF power is applied to 1 to 100W (watt) to the electrode 31 on which the wafer is placed in one step, plasma is generated in the chamber 33 to etch the wafer 31, but the wafer 31 Etching is performed to 10 to 50% of the thickness of the surface oxide film and the wafer surface film. Next, when the RF applied to the electrode 32 on which the wafer 31 is placed is turned off in two steps and the surface activated energy source 35 is irradiated onto the wafer 31 from the irradiation device 40 at the upper end of the chamber 33, the first step is performed. During etching, the etched surface is activated and reacts with radicals, so etching proceeds.

4A and 4B are cross-sectional views illustrating a state in which a gate pattern and a polysilicon layer are sequentially deposited on a silicon substrate, a mask pattern is formed, and then etched by the etching apparatus of FIG.

First, FIG. 4A shows that the gate silicon film 52 and the polysilicon layer 53 serving as the gate electrode are formed on the silicon substrate 51 so that the wafer having completed the mask pattern 54 is completed in one step. It is sectional drawing which shows the state which etched to 10 to 50% of the deposition thickness of the oxide film (not shown) and the polysilicon layer 53. FIG. At this time, in the etching method, when the wafer enters the chamber as described in FIG. 3, at the same time, a plasma is generated by applying an RF electrode of 1 to 100 W (w att) to the electrode on which the wafer is placed to generate the plasma. 55) and radical 56, but only 10 to 50% of the thickness of the polysilicon layer 53 is etched.

FIG. 4b shows that the RF power is not applied to the electrode on which the wafer is placed in the second step after the process of FIG. 4a, and only radicals 56 entering the chamber through the plasma tube are present in the chamber, and at the same time, the irradiation apparatus at the top of the chamber Irradiates the activation energy source 57 onto the wafer surface. Accordingly, only the surface to be etched by the surface activation energy source 57 is activated to be etched in response to the radical 56, and the sidewall portion of the polysilicon pattern 53 'is not irradiated with the surface activation energy source 57. It is not activated because it does not react with the radical 56.

As described above, the etching method using the etching apparatus of the present invention uses a radical and RF power in one step to etch about 10 to 50% of the thickness of the layer to be etched, and in two steps, such as radical, UV, LASER, X-RAY, etc. Anisotropic etching with high selectivity with the underlying structure can be achieved when etching using the surface activated energy source of, minimizing damage to the silicon substrate that can occur after the etching process and contributing to improving the yield of semiconductor devices. Is large.

Claims (11)

A plasma tube for introducing the gas activated by the microwave generator into the reaction chamber in which the wafer is placed; A reaction chamber in which the activated gas enters and reacts with a wafer placed on an electrode to which RF power is applied; And irradiating a surface activated energy source perpendicular to the wafer to an upper end of the chamber to activate the surface of the wafer, thereby providing a surface activated energy source irradiating device to help react with radicals introduced into the chamber through the plasma tube. Dry etching apparatus comprising a. The method of claim 1, wherein the plasma tube is guided by a wave guide from the microwave generator to form a gas flowing into the gas inlet into the plasma to introduce the activated gas into the chamber. Etching device. The dry etching apparatus according to claim 1 or 2, wherein the plasma tube is formed of quartz to prevent microwaves from being transmitted and influx of contaminants. The dry etching apparatus according to claim 1, further comprising a quartz plate formed between the irradiation device and the chamber to allow the surface activated energy source to pass therethrough. The dry etching apparatus of claim 1, further comprising a coolant inlet and an outlet configured to cool the chamber to maintain a constant temperature of the chamber on the chamber wall constituting the chamber. The dry etching apparatus of claim 1, further comprising a pumping line to maintain a high vacuum in the chamber. The dry etching apparatus of claim 1, wherein the surface activated energy source is any one of ultraviolet rays, lasers, and X-rays. The dry etching apparatus according to claim 1, wherein the RF power applied to the electrode on which the wafer is placed is 1 to 100W. The dry etching apparatus of claim 1, further comprising a coolant inlet and an outlet formed at the electrode to allow a coolant to flow the wafer to a predetermined temperature. When the wafer enters the chamber, RF power is applied to the electrode on which the wafer is placed to generate a plasma, and the etching target layer is etched using ions and radicals constituting the plasma, but only a predetermined thickness is etched. And preventing the RF power from being applied to the electrode on which the wafer is placed, allowing only the radicals entering the chamber through the plasma tube to be present in the chamber, and simultaneously irradiating surface activation energy onto the wafer surface from the irradiation device above the chamber. Dry etching apparatus characterized in that it comprises a second step to be etched by reacting with the radical. The dry etching method of claim 10, wherein 10 to 50% of the thickness to be etched is etched in the first step.