PRECISE ETCHING APPARATUS FOR PREPARING RECESSED-GATE ENHANCEMENT DEVICE AND ETCHING METHOD FOR THE SAME

Abstract

The present invention discloses a precise etching apparatus for preparing a recessed-gate enhancement device and an etching method for the same. The apparatus provided by the present invention includes an inductively-coupled plasma etching chamber, a current detection device, an inductive coil, a radio frequency source, a mechanical pump, and a molecular pump. The current detection device is connected with the inductively-coupled plasma etching chamber. The inductive coil is connected with the inductively-coupled plasma etching chamber. The radio frequency source is connected with the inductive coil. The mechanical pump and the molecular pump are connected with the inductively-coupled plasma etching chamber. When a displayed current value is zero during an HEMT device preparation process, the apparatus shuts off a two-dimensional electron gas channel, and etching is terminated, thereby preventing gate leakage caused by over-etching or damage to the two-dimensional electron gas channel, thus achieving precise etching.

Claims

1. A precise etching apparatus for preparing a recessed-gate enhancement device, comprising: an inductively-coupled plasma etching chamber, a current detection device, an inductive coil, a radio frequency source, a mechanical pump, and a molecular pump, wherein the current detection device is connected with the inductively-coupled plasma etching chamber via a wire, the inductive coil is connected with the inductively-coupled plasma etching chamber, the radio frequency source is connected with the inductive coil, and the mechanical pump and the molecular pump are connected with the inductively-coupled plasma etching chamber.

2. The precise etching apparatus for preparing a recessed-gate enhancement device according to claim 1, wherein the inductively-coupled plasma etching chamber comprises a chamber body, a base, a radio frequency bias power source, a plate-penetrating electrode, a probe, a ceramic bushing and a gas valve.

3. The precise etching apparatus for preparing a recessed-gate enhancement device according to claim 2, wherein the base is disposed at a bottom of the chamber body of the inductively-coupled plasma etching chamber; a lower portion of the base is connected with the radio frequency bias power source; the radio frequency bias power source increases bombarding energy of a plasma; the plate-penetrating electrode is disposed on a side wall of the chamber body of the inductively-coupled plasma etching chamber; one end of the plate-penetrating electrode is connected with the probe, and another end of the plate-penetrating electrode is connected to the current detection device.

4. The precise etching apparatus for preparing a recessed-gate enhancement device according to claim 2, wherein the probe is connected with source and drain electrodes on a substrate to be etched; the ceramic bushing is disposed on an upper portion of the chamber body of the inductively-coupled plasma etching chamber and is connected to the inductive coil; a top portion of the ceramic bushing is provided with the gas valve, and is communicated with a process gas pipeline via the gas valve.

5. The precise etching apparatus for preparing a recessed-gate enhancement device according to claim 2, wherein two valves which are respectively connected with the mechanical pump and the molecular pump are disposed at the bottom of the chamber body of the inductively-coupled plasma etching chamber; the mechanical pump and the molecular pump vacuumize the inner chamber body of the inductively-coupled plasma etching chamber via the valves and pump out a reaction gas in etching process.

6. The precise etching apparatus for preparing a recessed-gate enhancement device according to claim 1, wherein two plate-penetrating electrodes are disposed on the side wall of the chamber body of the inductively-coupled plasma etching chamber; in the chamber body of the inductively-coupled plasma etching chamber, the two plate-penetrating electrodes are respectively connected to two probes, and the two probes are connected with source and drain electrodes of a same unit on the substrate to be etched; the two plate-penetrating electrodes are connected with the current detection device to form a closed loop outside the chamber body of the inductively-coupled plasma etching chamber.

7. The precise etching apparatus for preparing a recessed-gate enhancement device according to claim 1, wherein the inductive coil is an inductively-coupled coil and wound on the ceramic bushing, a radio frequency current is applied to the inductive coil to produce an alternating magnetic field, such that a process gas is energized into a high-density plasma.

8. The precise etching apparatus for preparing a recessed-gate enhancement device according to claim 1, wherein the chamber body of the inductively-coupled plasma etching chamber is made of a high-pressure resistant alloy steel.

9. The precise etching apparatus for preparing a recessed-gate enhancement device according to claim 1, wherein the probe is a beryllium copper gold-plated probe.

10. An etching method for preparing a recessed-gate enhancement high electron mobility transistor (HEMT) device by using the precise etching apparatus according to claim 1, comprising the following steps: (1) sending the substrate to be etched into the chamber body of the inductively-coupled plasma etching chamber, wherein the substrate to be etched is put on the base; (2) respectively connecting the probes and the current detection device with the plate-penetrating electrodes; (3) respectively connecting the probes with source and drain electrodes of the same unit on the substrate to be etched, thus forming the closed loop circuit; (4) opening the valve connected with the mechanical pump and the molecular pump; vacuumizing the inner chamber body of the inductively-coupled plasma etching chamber with the mechanical pump and the molecular pump, and loading the etching gas; (5) switching on the radio frequency source and the radio frequency bias power (6) wherein, in etching process, the HEMT device has a constantly thinning barrier layer and the two-dimensional electron gas has a reduced concentration, and an output current also changes accordingly; an etching depth is real-timely monitored by observing current; an enhancement etching depth is achieved when a displayed current value is zero, then etching is terminated; (7) switching off the radio frequency source and the bias power source and sending out the etched substrate to obtain the recessed-gate enhancement HEMT device.

11. An etching method for preparing a recessed-gate enhancement high electron mobility transistor (HEMT) device by using the precise etching apparatus according to claim 2, comprising the following steps: (1) sending the substrate to be etched into the chamber body of the inductively-coupled plasma etching chamber, wherein the substrate to be etched is put on the base; (2) respectively connecting the probes and the current detection device with the plate-penetrating electrodes; (3) respectively connecting the probes with source and drain electrodes of the same unit on the substrate to be etched, thus forming the closed loop circuit; (4) opening the valve connected with the mechanical pump and the molecular pump; vacuumizing the inner chamber body of the inductively-coupled plasma etching chamber with the mechanical pump and the molecular pump, and loading the etching gas; (5) switching on the radio frequency source and the radio frequency bias power source to etch the substrate; (6) wherein, in etching process, the HEMT device has a constantly thinning barrier layer and the two-dimensional electron gas has a reduced concentration, and an output current also changes accordingly; an etching depth is real-timely monitored by observing current; an enhancement etching depth is achieved when a displayed current value is zero, then etching is terminated; (7) switching off the radio frequency source and the bias power source and sending out the etched substrate to obtain the recessed-gate enhancement HEMT device.

12. An etching method for preparing a recessed-gate enhancement high electron mobility transistor (HEMT) device by using the precise etching apparatus according to claim 3, comprising the following steps: (1) sending the substrate to be etched into the chamber body of the inductively-coupled plasma etching chamber, wherein the substrate to be etched is put on the base; (2) respectively connecting the probes and the current detection device with the plate-penetrating electrodes; (3) respectively connecting the probes with source and drain electrodes of the same unit on the substrate to be etched, thus forming the closed loop circuit; (4) opening the valve connected with the mechanical pump and the molecular pump; vacuumizing the inner chamber body of the inductively-coupled plasma etching chamber with the mechanical pump and the molecular pump, and loading the etching gas; (5) switching on the radio frequency source and the radio frequency bias power source to etch the substrate; (6) wherein, in etching process, the HEMT device has a constantly thinning barrier layer and the two-dimensional electron gas has a reduced concentration, and an output current also changes accordingly; an etching depth is real-timely monitored by observing current; an enhancement etching depth is achieved when a displayed current value is zero, then etching is terminated; (7) switching off the radio frequency source and the bias power source and sending out the etched substrate to obtain the recessed-gate enhancement HEMT device.

13. An etching method for preparing a recessed-gate enhancement high electron mobility transistor (HEMT) device by using the precise etching apparatus according to claim 4, comprising the following steps: (1) sending the substrate to be etched into the chamber body of the inductively-coupled plasma etching chamber, wherein the substrate to be etched is put on the base; (2) respectively connecting the probes and the current detection device with the plate-penetrating electrodes; (3) respectively connecting the probes with source and drain electrodes of the same unit on the substrate to be etched, thus forming the closed loop circuit; (4) opening the valve connected with the mechanical pump and the molecular pump; vacuumizing the inner chamber body of the inductively-coupled plasma etching chamber with the mechanical pump and the molecular pump, and loading the etching gas; (5) switching on the radio frequency source and the radio frequency bias power source to etch the substrate; (6) wherein, in etching process, the HEMT device has a constantly thinning barrier layer and the two-dimensional electron gas has a reduced concentration, and an output current also changes accordingly; an etching depth is real-timely monitored by observing current; an enhancement etching depth is achieved when a displayed current value is zero, then etching is terminated; (7) switching off the radio frequency source and the bias power source and sending out the etched substrate to obtain the recessed-gate enhancement HEMT device.

14. An etching method for preparing a recessed-gate enhancement high electron mobility transistor (HEMT) device by using the precise etching apparatus according to claim 5, comprising the following steps: (1) sending the substrate to be etched into the chamber body of the inductively-coupled plasma etching chamber, wherein the substrate to be etched is put on the base; (2) respectively connecting the probes and the current detection device with the plate-penetrating electrodes; (3) respectively connecting the probes with source and drain electrodes of the same unit on the substrate to be etched, thus forming the closed loop circuit; (4) opening the valve connected with the mechanical pump and the molecular pump; vacuumizing the inner chamber body of the inductively-coupled plasma etching chamber with the mechanical pump and the molecular pump, and loading the etching gas; (5) switching on the radio frequency source and the radio frequency bias power source to etch the substrate; (6) wherein, in etching process, the HEMT device has a constantly thinning barrier layer and the two-dimensional electron gas has a reduced concentration, and an output current also changes accordingly; an etching depth is real-timely monitored by observing current; an enhancement etching depth is achieved when a displayed current value is zero, then etching is terminated; (7) switching off the radio frequency source and the bias power source and sending out the etched substrate to obtain the recessed-gate enhancement HEMT device.

15. An etching method for preparing a recessed-gate enhancement high electron mobility transistor (HEMT) device by using the precise etching apparatus according to claim 6, comprising the following steps: (1) sending the substrate to be etched into the chamber body of the inductively-coupled plasma etching chamber, wherein the substrate to be etched is put on the base; (2) respectively connecting the probes and the current detection device with the plate-penetrating electrodes; (3) respectively connecting the probes with source and drain electrodes of the same unit on the substrate to be etched, thus forming the closed loop circuit; (4) opening the valve connected with the mechanical pump and the molecular pump; vacuumizing the inner chamber body of the inductively-coupled plasma etching chamber with the mechanical pump and the molecular pump, and loading the etching gas; (5) switching on the radio frequency source and the radio frequency bias power source to etch the substrate; (6) wherein, in etching process, the HEMT device has a constantly thinning barrier layer and the two-dimensional electron gas has a reduced concentration, and an output current also changes accordingly; an etching depth is real-timely monitored by observing current; an enhancement etching depth is achieved when a displayed current value is zero, then etching is terminated; (7) switching off the radio frequency source and the bias power source and sending out the etched substrate to obtain the recessed-gate enhancement HEMT device.

16. An etching method for preparing a recessed-gate enhancement high electron mobility transistor (HEMT) device by using the precise etching apparatus according to claim 7, comprising the following steps: (1) sending the substrate to be etched into the chamber body of the inductively-coupled plasma etching chamber, wherein the substrate to be etched is put on the base; (2) respectively connecting the probes and the current detection device with the plate-penetrating electrodes; (3) respectively connecting the probes with source and drain electrodes of the same unit on the substrate to be etched, thus forming the closed loop circuit; (4) opening the valve connected with the mechanical pump and the molecular pump; vacuumizing the inner chamber body of the inductively-coupled plasma etching chamber with the mechanical pump and the molecular pump, and loading the etching gas; (5) switching on the radio frequency source and the radio frequency bias power source to etch the substrate; (6) wherein, in etching process, the HEMT device has a constantly thinning barrier layer and the two-dimensional electron gas has a reduced concentration, and an output current also changes accordingly; an etching depth is real-timely monitored by observing current; an enhancement etching depth is achieved when a displayed current value is zero, then etching is terminated; (7) switching off the radio frequency source and the bias power source and sending out the etched substrate to obtain the recessed-gate enhancement HEMT device.

17. An etching method for preparing a recessed-gate enhancement high electron mobility transistor (HEMT) device by using the precise etching apparatus according to claim 8, comprising the following steps: (1) sending the substrate to be etched into the chamber body of the inductively-coupled plasma etching chamber, wherein the substrate to be etched is put on the base; (2) respectively connecting the probes and the current detection device with the plate-penetrating electrodes; (3) respectively connecting the probes with source and drain electrodes of the same unit on the substrate to be etched, thus forming the closed loop circuit; (4) opening the valve connected with the mechanical pump and the molecular pump; vacuumizing the inner chamber body of the inductively-coupled plasma etching chamber with the mechanical pump and the molecular pump, and loading the etching gas; (5) switching on the radio frequency source and the radio frequency bias power source to etch the substrate; (6) wherein, in etching process, the HEMT device has a constantly thinning barrier layer and the two-dimensional electron gas has a reduced concentration, and an output current also changes accordingly; an etching depth is real-timely monitored by observing current; an enhancement etching depth is achieved when a displayed current value is zero, then etching is terminated; (7) switching off the radio frequency source and the bias power source and sending out the etched substrate to obtain the recessed-gate enhancement HEMT device.

18. An etching method for preparing a recessed-gate enhancement high electron mobility transistor (HEMT) device by using the precise etching apparatus according to claim 9, comprising the following steps: (1) sending the substrate to be etched into the chamber body of the inductively-coupled plasma etching chamber, wherein the substrate to be etched is put on the base; (2) respectively connecting the probes and the current detection device with the plate-penetrating electrodes; (3) respectively connecting the probes with source and drain electrodes of the same unit on the substrate to be etched, thus forming the closed loop circuit; (4) opening the valve connected with the mechanical pump and the molecular pump; vacuumizing the inner chamber body of the inductively-coupled plasma etching chamber with the mechanical pump and the molecular pump, and loading the etching gas; (5) switching on the radio frequency source and the radio frequency bias power source to etch the substrate; (6) wherein, in etching process, the HEMT device has a constantly thinning barrier layer and the two-dimensional electron gas has a reduced concentration, and an output current also changes accordingly; an etching depth is real-timely monitored by observing current; an enhancement etching depth is achieved when a displayed current value is zero, then etching is terminated; (7) switching off the radio frequency source and the bias power source and sending out the etched substrate to obtain the recessed-gate enhancement HEMT device.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Description of the Drawings

[0040] FIG. 1 shows a structure diagram of a precise etching apparatus for preparing a recessed-gate enhancement device provided by the present invention.

[0041] FIG. 2 is a front view showing connection between plate-penetrating electrodes and an inductively-coupled plasma etching chamber in the precise etching apparatus for preparing a recessed-gate enhancement device provided by the present invention.

[0042] 1: inductively-coupled plasma etching chamber, 2: base, 3: radio frequency bias power source, 4: plate-penetrating electrode, 5: probe, 6: current detection device, 7: ceramic bushing, 8: inductive coil, 9: gas valve, 10: radio frequency source, 11: mechanical pump, and 12: molecular pump.

EXAMPLES OF THE INVENTION

[0043] Detailed Description of the Embodiments

[0044] The present invention will be further described in combination with the drawings and examples of the description. But the embodiments and protection scope of the present invention are not limited thereto. It should be pointed that any process not described in detail particularly may be achieved and understood by reference to the prior art by a person skilled in the art.

EXAMPLE 1

[0045] The structure diagram of the precise etching apparatus of the present invention is shown in FIG. 1, and includes an inductively-coupled plasma etching chamber 1, a current detection device 6, an inductive coil 8, a radio frequency source 10, a mechanical pump 11 and a molecular pump 12.

[0046] A base 2 is disposed in a central position at the bottom of the chamber body of the inductively-coupled plasma etching chamber 1, used for putting a substrate to be etched. The base 2 is connected with the radio frequency bias power source 3. The radio frequency bias power source 3 provides the bombarding energy of a plasma.

[0047] Two plate-penetrating electrodes 4 are disposed in a central position on a side wall of the chamber body of the inductively-coupled plasma etching chamber 1; the inner structure of the plate-penetrating electrodes and the inner structure is connected with the inductively-coupled plasma etching chamber, as shown in FIG. 2. Each plate-penetrating electrode includes a thick lead-out tube 101, a fine lead-out tube 102 and a lead, where the thick lead-out tube is connected with a side wall 103 of the chamber body of the inductively-coupled plasma etching chamber, and is in threaded connection with the fine lead-out tube; the fine wire hole contains a continuous wire lead. In the chamber body of the inductively-coupled plasma etching chamber 1, two plate-penetrating electrodes 4 are respectively connected with two probes 5, and the two probes 5 are respectively connected with source and drain electrodes of the same unit on the substrate to be etched; two plate-penetrating electrodes 4 are connected with the current detection device 6 to form a circuit loop outside the chamber body of the inductively-coupled plasma etching chamber 1.

[0048] A ceramic bushing 7 is disposed on an upper portion of the chamber body of the inductively-coupled plasma etching chamber 1; an inductive coil 8 is wound outside the ceramic bushing 7, and the top portion thereof is provided with a gas valve 9; the inductive coil 8 is connected with the radio frequency source 10 to form an inductance alternating magnetic field, such that a process gas from the gas valve 9 is energized into a plasma.

[0049] Valves which are respectively connected to the mechanical pump 11 and the molecular pump 12 are disposed at the bottom of the chamber body of the inductively-coupled plasma etching chamber 1, such that the mechanical pump 11 and the molecular pump 12 may vacuumize the chamber body 1 of the inductively-coupled plasma etching chamber and pump out a reaction gas in etching process timely.

EXAMPLE 2

[0050] Example 2 is set as an example to describe the etching method of the present invention; an etching method for preparing a recessed-gate enhancement HEMT device by using the above precise etching apparatus includes the following steps.

[0051] (1) A substrate to be etched was sent into the chamber body of the inductively-coupled plasma etching chamber 1, where the substrate to be etched was put on the base 2;

[0052] (2) The current detection device 6 was connected with two plate-penetrating electrodes 4;

[0053] (3) Two probes 5 were respectively connected with the two plate-penetrating electrodes 4, and were adjusted such that the probes 5 were respectively connected with source and drain electrodes of the same unit on the substrate device to be etched, thus forming a closed loop;

[0054] (4) The mechanical pump 11 was switched on to vacuumize the chamber body of the inductively-coupled plasma etching chamber 1;

[0055] (5) When the vacuum degree was pumped to 150 m Torr, the molecular pump 12 was switched on to further vacuumize till the chamber body had an internal pressure of 5 mT;

[0056] (6) A mixed gas of Cl.sub.2 and BCl.sub.3 was loaded via the gas valve 9;

[0057] (7) The radio frequency source 10 was switched on, and a power parameter was set as 250 W; a radio frequency current was applied to the inductive coil 8 connected with the radio frequency source, such that an alternating magnetic field was produced within the ceramic bushing 7 wound by the inductive coil, and then the mixed gas of Cl.sub.2 and BCl.sub.3 was energized into a plasma.

[0058] (8) The radio frequency bias power source 3 was switched on, and a power parameter was set as 30 W to increase the ion bombarding energy;

[0059] (9) In the etching process, the current variation was observed by the current detection device 6; when a displayed current value was zero, the etching was terminated; then the radio frequency source 10 and the radio frequency bias power source 3 were switched off;

[0060] (10) At the end of the etching, the etched substrate was sent out to obtain the recessed-gate enhancement HEMT device.

[0061] This example skillfully utilizes the relational characteristics between the thickness of a barrier layer in the GaN HMET device and the concentration of the two-dimensional electron gas to be skillfully transformed into the relationship between the etching depth and the current value. The etching depth is monitored by directly observing the current variation, when a displayed current value is zero, the etching is terminated. The present invention is visual, and has high precision and strong operability.

[0062] What is described above are merely detailed embodiments in the present application. It should be indicated that a person skilled in the art may make various corresponding changes and transformations according to the above technical solution described above and concept within the principle of the present application. Moreover, all of these changes and transformations should fall within the protection scope of the claims of the present invention.