JPH07106305A - Atom layer etching unit - Google Patents

Abstract

PURPOSE:To prevent the machining accuracy of etching from being impaired to allow process inspection by using a shroud having a transfer function and a gas adsorption function as a means of collecting and removing unnecessary particles. CONSTITUTION:An etching processing chamber 101 an adsorbed substance analysis chamber 102 are separated by a gate valve 103. A sample 104 to be etched, a sample stage 105, an electron gun 107, sputter ion gun 108, and an ion gauge 109 are arranged in the etching gas processing chamber 101. A quadrupole mass analyzer 110 is mounted on the sucked substance analysing chamber 102. A shroud 111 can move between the etching processing chamber 101 and the absorbed substance analyzing chamber 102 by means of a moving function 112. Moreover, the etching processing chamber 101 is connected to an STM device 113 to measure the machining accuracy of the etching. The STM device 113 has a transfer mechanism 114 and separated by a gate valve 115 from the etching processing chamber 101.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor element surface processing process, and more particularly to an atomic layer etching apparatus for performing etching with atomic level processing accuracy.

[0002]

2. Description of the Related Art As the demand for processing accuracy of semiconductor etching approaches the atomic level, when cleaning the semiconductor surface, modifying the semiconductor surface, or etching the atomic layer from the semiconductor surface, the surface of the sample is The influence of the particles reflected or desorbed from the surface of the sample on the processing accuracy becomes significant. This is because particles unnecessary for these processes react with the surface again, causing unnecessary progress of etching or inhibition of etching.

Conventionally, a pump attached to the exhaust port has been used to remove these particles from the vacuum chamber. However, in such a method, many of these particles collide with the wall of the vacuum chamber several times and then adsorb to the wall or enter the exhaust port and are removed from the gas phase. Therefore, in such a method, it is feared that these particles may be detached from the wall or reflected by the wall, and may reach the surface of the sample again to affect the state of the surface.

On the other hand, the particles unnecessary for the above-mentioned process reflect the conditions of the process of cleaning the surface, the process of modifying the surface by element adsorption or the like, and the process of etching the atomic layer on the surface. . However, conventional methods that use pumps attached to the exhaust port do not collect these particles for analytical purposes, so inspecting these particles to assess whether the process was adequate. It is difficult.

Another conventional method is a method (FIG. 2) used in an MBE device or the like. In this method, a low temperature shroud 202 fixedly installed inside the vacuum chamber 201 along the container wall is used to collect particles unnecessary for the process. However, in this method, the steps for desorbing the particles adsorbed on the shroud 202 and restoring the shroud 202 to a clean state must be performed in the same vacuum chamber 201 where the process is performed. Therefore,
Particles detached from the shroud 202 adhere to the molecular source 203 and the measuring instrument 204 installed in the same vacuum chamber 201,
These are sources of process contamination. When desorbing the particles adsorbed on the shroud 202, it is possible to separately provide a preliminary chamber and evacuate the sample stage 205 and the sample 206. However, evacuating the molecular source 203 and the measuring instrument 204 at the same time means that It is not a good idea because it causes complication.

[0006]

In the conventional method described above, it is not possible to sufficiently prevent particles unnecessary for the process from reacting again with the surface of the sample, and the etching processing accuracy is impaired.

An object of the present invention is to provide an atomic layer etching apparatus having a function of inspecting a process by analyzing these particles while avoiding that these particles impair the processing accuracy of etching. That is.

[0008]

In order to achieve the above object, a shroud having a transfer function and a gas adsorption function is used as a means for collecting and removing unnecessary particles in the above-mentioned process. At the same time that the particles adsorbed to the shroud are desorbed and the shroud is restored to a clean state, at the same time, as a means for inspecting the process, an adsorbate analysis chamber that is separate from the etching chamber is provided and The particles are analyzed by an elemental analyzer installed in the adsorbate analysis room.

[0009]

The operation of the present invention will be described below with reference to FIG. Figure 3
(a) shows a step of irradiating the surface of the sample with ions or radicals to clean the surface of the sample as one step of the atomic layer etching. Ions or radicals are supplied from the ion-radical source 301 to the surface of the sample 303 placed on the sample table 302. Part of this acts on the surface of the sample 303. Gas or sample 30 that did not act on the surface of sample 303 due to reflection on the surface of sample 303
The particles desorbed from the surface of No. 3 are the etching processing chamber 304.
It remains in the gas phase inside and on the wall.

An example in which the atomic layer etching apparatus of the present invention is used in this step is shown in FIG. 3 (b). Ion-radical source 3
When the ions or radicals are supplied to the surface of the sample 303 from 01, the ions or radicals that did not act on the surface of the sample 303 and the particles desorbed from the surface of the sample 303 are collected by the shroud 305 kept at a low temperature. It This is because particles are likely to be adsorbed on the solid surface at low temperature,
It also utilizes the effect that it is difficult to desorb once it is adsorbed.
Thus, the number of these particles remaining in the etching treatment chamber 304 after that is extremely small as compared with the case where this method is not used. Even when the sample 303 is heated to clean the sample surface by using the heating function provided in the sample table 302 instead of irradiating the sample 303 with ions or radicals, the cleaning method of the etching process of the present invention is It can be used similarly. A gas containing halogen or the like is supplied to the surface of the sample 303 to form an adsorption layer of an appropriate element, or the surface of the sample 303 having the appropriate element thus adsorbed is irradiated with an energy beam generated by an energy beam source. The present invention can be similarly applied to the case of etching the atomic layer on the surface of the sample 303. In this case, the ions for cleaning the surface of the sample mentioned above
Instead of the radical source 301, a gas source 306 for supplying a gas to the surface of the sample 303 or an energy beam source 307 for etching an atomic layer on the surface of the sample may be used.

FIG. 3 (c) shows a step of recovering the shroud having adsorbed particles unnecessary for the process to a clean state and at the same time, analyzing these particles and inspecting the process. Particles not needed for the process are cold shroud 30
5, the low temperature shroud 305 is moved from the etching processing chamber 304 to the adsorbate analysis chamber 309 by the moving function 308.

After that, the gate valve 310 is closed and the etching processing chamber 304 and the adsorbate analysis chamber 309 are separated.
By raising the temperature of the low temperature shroud 305 in the adsorbate analysis chamber 309 and desorbing the particles adsorbed to the low temperature shroud 305, the shroud can be recovered to a clean state. The particles desorbed from the low temperature shroud 305 are used in the elemental analysis device 31 installed in the adsorbate analysis chamber 309.
1 and used for inspection of the etching process. Even when the shroud 305 at low temperature is irradiated with electrons or ions instead of raising the temperature of the shroud 305 at low temperature to recover the shroud to a clean state and the etching inspection is performed from the analysis of desorbed particles, the present invention is also applicable. The inspection method of the etching process can be used similarly.

Unlike the method of directly observing the particles desorbed from the surface of the sample 303, the method of the present invention once collects these particles by the low temperature shroud 305, moves them to the adsorbate analysis chamber 309, and then adsorbs them. Since the desorption of particles and the analysis thereof are performed, there is a feature that the inspection method has an extremely small influence on the etching process performed in the etching processing chamber 304. Therefore, as compared with the case shown in FIG. 3A, it is possible to realize etching with extremely high finishing accuracy.

[0014]

FIG. 1 is a schematic diagram of an atomic layer etching apparatus which realizes the present invention. This equipment is used in the etching chamber 1
01 and adsorbate analysis chamber 102, which are separated by a gate valve 103. Etching chamber 10
1. The adsorbate analysis chamber 102 is maintained at a vacuum degree of 10 ⁻⁸ Pa. In the etching processing chamber 101, a sample 104 to be etched, a sample stage 105 having a heating and cooling function, a gas source 106, an electron gun 107, a sputter ion gun 108, and an ion gauge 109 are arranged as shown in the figure. .

A quadrupole mass spectrometer 110 is attached to the adsorbate analysis chamber 102. The shroud 111 kept at a low temperature of 85 K by pouring liquid nitrogen through the pipe uses the transfer function 112 to move the main reaction chamber 101.
And the preliminary reaction chamber 102 can be moved. Further, the etching processing chamber 101 is connected to an STM device 113 for measuring the processing accuracy of etching.
The STM device 113 includes a moving mechanism 114 and is separated from the etching processing chamber 101 by a gate valve 114.

A GaAs100 substrate was used as the sample.
While the sample 104 is heated to 430 ° C. in the etching processing chamber 101, the sample 104 is irradiated with Ar + ions for 30 minutes by using the sputter ion gun 108, and then at 550 ° C. for 3 minutes.
The sample 104 was heated for a minute to remove contaminants on the surface of the sample 104. At this time, the particles detached from the surface of the sample 104 were collected by using the low temperature shroud 111.

The low-temperature shroud 111 is moved to the adsorbate analysis chamber 102, the gate valve 103 is closed, and the particles desorbed when the temperature of the shroud 111 is raised by the heating function are measured by using the quadrupole mass spectrometer 110. As a result of the analysis,
Ga and As which are substrate components, and O which is a contaminant
And C signals were detected. From this, it was found that in the above-described sample cleaning method, desorption of the contaminants O and C and desorption of the substrate constituent elements Ga and As occur simultaneously. Further, due to this temperature rise, particles adsorbed on the surface of the shroud 111 when the sample was cleaned were desorbed, and the shroud 111 was restored to a clean state. By this sample surface cleaning treatment, the outermost surface atomic layer of the sample 104 was reconstituted and became a clean Ga atomic layer with a uniform atomic arrangement.

Thereafter, the sample 104 is cooled to 85K,
In the etching processing chamber 101, the sample 104 was exposed to chlorine generated from the gas source 106 to form a chlorine adsorption layer. In this step, if the low temperature shroud is not used, the pressure in the etching processing chamber 101 is 10 ⁻⁷ Pa.
It rose to the table. However, when the same chlorine adsorption was carried out using the low temperature shroud 111, no pressure increase in the reaction chamber was observed. This is the chlorine that was not adsorbed on the sample 104 among the chlorine supplied from the gas source 106,
Alternatively, it is shown that particles desorbed from the surface of the sample 104 at the time of chlorine adsorption are adsorbed to the low temperature shroud 111 and are reliably recovered.

Thereafter, the low temperature shroud 111 is moved to the adsorbate analysis chamber 102, the gate valve 103 is closed, and the particles desorbed when the temperature of the shroud 111 is raised by the heating function are quadrupole mass spectrometer 110. As a result of analysis using, a chlorine signal was detected. Also, at this time,
Neither species including the substrate constituent elements Ga and As were detected, and it was confirmed that Ga and As were not desorbed in the chlorine adsorption step.

After the chlorine adsorption layer is formed on the surface of the sample 104 in this way, a 4 keV electron beam generated by the electron gun 107 is used as an energy beam for etching the sample 1.
The surface of No. 04 was irradiated and the Ga atomic layer was etched. At this time, particles detached from the surface by electron beam irradiation were collected by the low temperature shroud 111. Then, the low temperature shroud 111 is removed from the adsorbate analysis chamber 102.
The quadrupole mass spectrometer 110 analyzed the particles desorbed when the temperature of the shroud 111 was raised by moving the gate valve 103 and closing the gate valve 103, and as a result, in addition to the chlorine signal, the Ga signal was detected. was detected. At this time, a species containing As was not detected. Thus, it was found that the Ga atomic layer was etched by the 4 keV electron beam.

In order to compare the etching processing accuracy when the particles unnecessary for the process are recovered by using the low temperature shroud 111 with the STM apparatus 113, the etching accuracy after the etching is compared by using the STM apparatus 113. The surface roughness was evaluated. As a result, the cold shroud 11
It was found that when 1 was not used, an average roughness of 30 Å remained, but when the low temperature shroud 111 was used, an average flatness of 2 Å was obtained.

In this embodiment, ions are irradiated to clean the surface of the sample 104, but when the surface of the sample 104 is cleaned by irradiating radicals such as hydrogen radicals instead of the ions. However, the present invention can be used similarly.
Although chlorine gas is supplied from the gas source 106 to form an adsorption layer on the surface of the sample 104, the sample 104 is prepared by using a gas containing another halogen element or a Group VI element such as oxygen or selenium. The present invention can be similarly applied to the case of modifying the surface of. Further, although an electron beam is used as an energy beam for etching, the present invention can be similarly used when etching is performed using light, ions or radicals. The present invention can also be used in the same manner when etching is performed by raising the temperature of the sample 104 that has adsorbed the gas without using the energy beam. Also,
Although liquid nitrogen is used to cool the shroud in this embodiment, a chiller using liquid helium or a compressor may be used instead. In addition, in the present embodiment, the particles adsorbed to the shroud 111 are desorbed and analyzed, and at the same time, the temperature of the shroud 111 is raised in order to restore the shroud 111 to a clean state. The present invention can also be applied to the case where the adsorbed particles are desorbed by irradiating with. Further, although the Ga atomic layer is etched from the GaAs surface in this embodiment, the present invention can be similarly applied to the case where the As atomic layer is etched from the GaAs surface and other materials are etched.

As described above, the processing accuracy of etching is improved by collecting particles unnecessary for the process by the shroud having the cooling function and the moving function. In addition, by analyzing the collected particles, it became possible to simultaneously inspect the process.

[0024]

By using the shroud having the cooling function and the moving function, the particles unnecessary for the process (particles reflected on the surface of the sample or particles desorbed from the surface of the sample) are collected, so that the etching processing accuracy is improved. In addition, by analyzing the collected particles, it became possible to simultaneously inspect the process.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of an atomic layer etching apparatus used in a first embodiment of the present invention.

FIG. 2 is an explanatory view of an apparatus using a conventional method.

FIG. 3 is an explanatory diagram of an atomic layer etching apparatus of the present invention.

[Explanation of symbols]

101 ... Etching processing room, 102 ... Adsorbate analysis room, 1
03 ... Gate valve, 104 ... Sample, 105 ... Sample stand,
106 ... Gas source, 107 ... Electron gun, 108 ... Sputter ion gun, 109 ... Ion gauge, 110 ... Quadrupole mass spectrometer, 111 ... Shroud, 112 ... Moving function, 113
… Movement function, 114… STM device, 115… Gate valve.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Seiji Yamamoto 1-280 Higashi Koikekubo, Kokubunji City, Tokyo Inside the Central Research Laboratory, Hitachi, Ltd.

Claims (15)

[Claims] 1. An atomic layer etching apparatus, wherein a shroud having a gas adsorption function can be moved by a moving function between an etching processing chamber and an adsorbate analysis chamber which are separated from each other. 2. A sample installed in the etching chamber is heated by using a heating function provided on a sample table, and particles desorbed from the surface of the sample are adsorbed to the shroud. Atomic layer etching equipment that collects and recovers. 3. The method according to claim 1, wherein a gas source is installed in the etching processing chamber, the gas is supplied to the surface of the sample installed in the etching processing chamber, and the gas is reflected on the surface of the sample or desorbed from the surface of the sample. Atomic layer etching apparatus for adsorbing and recovering the particles to be absorbed by the shroud. 4. The energy beam source according to claim 1, wherein an energy beam source is connected to the etching processing chamber, and the energy beam is applied to the surface of the sample installed in the etching processing chamber, and the energy beam is reflected on the surface of the sample or An atomic layer etching apparatus for adsorbing particles desorbed from the surface to the shroud for recovery. 5. The shroud according to claim 2, wherein after the particles are collected, the shroud is moved from the etching processing chamber to the adsorbate analysis chamber, and the shroud is heated by using a heating function provided in the shroud. An atomic layer etching apparatus for desorbing particles adsorbed on the shroud. 6. The method according to claim 2, 3 or 4, wherein after the particles are collected, the shroud is moved from the etching processing chamber to the adsorbate analysis chamber and generated by an electron-ion source installed in the adsorbate analysis chamber. An atomic layer etching apparatus for irradiating the shroud with electrons or ions to desorb particles adsorbed on the shroud. 7. The method according to claim 2, 3 or 4, after the particles are collected, the shroud is moved from the etching processing chamber to the adsorbate analysis chamber, and the particles adsorbed by the shroud are set in the adsorbate analysis chamber. Atomic layer etching equipment for analysis using elemental analysis equipment. 8. The method according to claim 2, 3 or 4, wherein after the particles are collected, the shroud is moved from the etching processing chamber to the adsorbate analysis chamber, and the heating function provided in the shroud is used to raise the temperature of the shroud. An atomic layer etching apparatus for analyzing particles desorbed from the shroud using an elemental analysis apparatus installed in an adsorbate analysis chamber. 9. The particle shroud according to claim 2, 3 or 4, after the particles are collected, the shroud is moved from the etching processing chamber to the adsorbate analysis chamber and generated by an electron-ion source installed in the adsorbate analysis chamber. An atomic layer etching apparatus which irradiates the shroud with electrons or ions and analyzes the particles desorbed from the shroud using an elemental analysis apparatus installed in an adsorbate analysis chamber. 10. An atomic layer etching apparatus in which the elemental analyzer according to claim 8 or 9 is a mass spectrometer. 11. An atomic layer etching apparatus, wherein the gas according to claim 3 is a gas containing a halogen element or a VI group element. 12. The energy beam according to claim 4,
Atomic layer etching equipment that uses light, electrons, ions, radicals, and neutral excited species. 13. An atomic layer etching apparatus in which the ions according to claim 12 are ions of a rare gas. 14. An atomic layer etching apparatus in which the radical according to claim 12 is a hydrogen radical. 15. The gas adsorption function according to claim 1, wherein the shroud is cooled by flowing liquid nitrogen or liquid helium through a pipe through the shroud, or by cooling the shroud using a compressor. Atomic layer etching equipment.