TW201527584A - Method for removing deposits on the walls of a processing chamber - Google Patents

Abstract

The invention relates to a method for removing deposits on the walls/surfaces of a processing chamber of a CVD reactor, in particular from the SiC-coated graphite surfaces, wherein the processing chamber is heated to a cleaning temperature and a cleaning gas, in particular containing an element of the VII primary group, is introduced into the processing chamber for a cleaning period. In order to improve or to enable cleaning of a processing chamber, according to the invention the walls/surfaces to be cleaned are covered by a metal, in particular aluminum, before the introduction of the cleaning gas.

Description

Method of removing deposits on the walls of a processing chamber

The present invention relates to a method for removing deposits from a processing chamber wall of a CVD reactor, particularly a self-coated SiC graphite component, wherein the processing chamber is heated to a cleaning temperature and introduced into the processing chamber for a period of cleaning time. A cleaning gas for the element of the VII main group.

US 2013/0005118 A1, US Pat. No. 8,334,166 B2 and US Pat. No. 7,842,588 B2 disclose the deposition of a Group III-V semiconductor layer on a substrate composed, for example, of a Group III-V single crystal. The substrates may also be formed by corresponding lattice matching iridium. TMGa or TMAl is introduced into the processing chamber of the CVD reactor along with NH ₃ , PH ₃ or AsH ₃ to deposit a III-V layer. In order to clean the substrates after the deposition process is completed and the substrate is removed from the processing chamber, Cl _{2 is introduced} as a purge gas into the processing chamber along with an inert gas such as argon or nitrogen. Thereby an etching process is carried out at a temperature between 550 ° C and 1050 ° C, during which the parasitic coating formed on the walls of the processing chamber, in particular the SiC-coated graphite component, is mainly converted into volatile chlorides, which are carried by The gas stream is taken away from the processing chamber.

DE 10 2011 056 538 A1 discloses a method of introducing a HCl by H ₂ pulse to clean a processing chamber. The intermediate product gallium is formed during cleaning.

US 2004/0244817 A1 describes a method of cleaning a turbine blade using a multi-component etchant. The etchant contains, for example, NH ₄ Cl or a metal component of aluminum or chromium.

DE 10 2012 101 438 A1 and US 2011/0223710 A1 each describe a method of cleaning a processing chamber by introducing a cleaning gas, wherein the cleaning gas directly contacts the coating on the surface.

US 2011/0268880 A1 and US 5,976,396 each describe an etching process using a multi-component etchant. The multi-component etchant directly contacts the wall to be cleaned.

The SiN layer is mainly applied as a passivation layer to the HEMT structure, and the SiN layer is deposited to introduce silane (SiH ₄ ) into the processing chamber. It forms SiN together with NH ₃ introduced into the processing chamber. Silizium nitrile is formed not only on the surface of the substrate but also on the surface of the treatment chamber wall, particularly on the bottom of the treatment chamber. The chamber wall is composed of carbon coated bismuth (SiC) graphite. The treatment chamber wall cannot be cleaned with chlorine as a purge gas because SiN will become an etch barrier for chlorine-containing etching gases.

It is an object of the present invention to provide a method which is capable of cleaning a processing chamber and improving the cleaning effect of the processing chamber.

The invention as set forth in the scope of the patent application is a solution for achieving this object.

The invention first and mainly proposes a solution for wetting the wall to be cleaned with metal before introducing the cleaning gas. It is preferably carried out at elevated temperatures wherein the temperature of the wetting stage can be above 550 °C. In particular, the susceptor temperature or process chamber temperature may be ramped from a lower temperature to a maximum temperature of, for example, 1150 ° C during the wetting phase. This results in a temperature ramp during which a metal-containing gaseous starting material is simultaneously introduced into the processing chamber, which forms a metal condensate on the wall. The metal-containing starting material is preferably an organometallic compound which is introduced into the processing chamber along with a carrier gas such as hydrogen, nitrogen or a noble gas. The organometallic compound decomposes at the elevated temperature described above, wherein a thinner liquid metal film is condensed on the wall. According to a preferred embodiment of the present invention, the amount of metal fed into the processing chamber can form at least a closed metal film on the wall to be cleaned, in particular at least a single layer of a metal film. The metal may specifically be aluminum, gallium or indium. The gaseous carrier of the metals may be TMAl, TMGa, TEGa or TMIn. It is also possible here to start introducing the organometallic compound at a lower temperature, in which the temperature of the susceptor or the wall of the treatment chamber is continuously increased to the highest value. The base heated from below can be used as a heat source to heat the chamber walls. The susceptor heats the remaining walls of the processing chamber in a thermally radiated manner such that the final temperature reached by the walls is lower than the temperature of the susceptor surface. The introduction of the metal-containing gas can be started before all the walls of the processing chamber reach a temperature at which the metal-containing gas such as the organometallic compound is pyrolyzed into a metal. According to a first variant, the treatment chamber is flushed under reduced total gas pressure, as appropriate, after a wetting phase has been carried out during a short stop flush. The cleaning gas is then introduced into the processing chamber along with the carrier gas. The cleaning gas is preferably Cl ₂ . However, other elements of the VII main group or other etching gases or compounds of the VII main group elements such as HCl may also be used. The etching step is carried out, for example, at a temperature between 500 ° C and 1000 ° C. The wetting step and the subsequent washing step can be carried out in turn as a sequence of steps. According to one aspect of the method, a thinner III-V layer is applied to the liquid metal layer after the wetting step. The liquid metal layer only needs to have a thickness of a single layer. However, it may also have a thickness of several single layers. A III-V layer such as an AlN layer is directly deposited on the metal film by introducing NH ₃ along with the metal-containing gas such as TMAl. The layer thickness is approximately in the range of 30 nm. A GaN layer may be deposited on the AlN layer. This can be achieved by simultaneously introducing NH ₃ and TMGa. The GaN layer preferably has a layer thickness of up to 500 nm. After the rinsing is stopped for a short period of time and the total pressure of the processing chamber is lowered as appropriate, the washing step is carried out by introducing a cleaning gas such as Cl ₂ and a carrier gas. The introduction of NH ₃ can already be started before the above temperature ramp reaches its maximum above 1000 ° C, in particular above 1200 ° C. It has been shown that the wetting of the SiN coating with a metal, in particular liquid aluminum, enables the reactive liquid metal to exert an influence on the (opening) of the SiN bond, so that the SiN layer or the alloy formed by the metal can be converted to volatilized by the addition of chlorine. The compound is then transported away from the volatile compound by a carrier gas stream. In the second variant, the sequence of steps can also be carried out in succession. However, this solution preferably repeats the III-V coating process and the subsequent cleaning process by introducing a cleaning gas.

An embodiment of the present invention will now be described with reference to FIG.

Figure 1 is a flow chart with time as the horizontal axis and total pressure and susceptor temperature as the vertical axis. The time scale interval is 15 minutes.

The cleaning process shown in Figure 1 begins at an elevated temperature of about 200 °C. An inert gas or hydrogen gas is first fed to the process chamber. The chamber pressure was adjusted to 100 mbar. Then go through a temperature ramp. When the temperature reached 550 ° C, TMAl was introduced into the processing chamber, which decomposed on the surface of the high temperature substrate, in which liquid aluminum and gaseous methane were formed. Gaseous methane is carried away by the carrier gas. The remaining aluminum will be wetted by the surface of the SiN contaminated processing chamber wall to form at least one monolayer (100%-ige Monolage) at a concentration of 100%.

After about 7 minutes and after the temperature reached about 1050 ° C, NH ₃ was introduced into the process chamber and the process chamber pressure was increased to 200 mbar by feeding a corresponding amount of carrier gas. After depositing a layer of AlN having a thickness of about 30 nm, TMGa was used instead of TMAl to introduce a processing chamber to deposit a GaN layer of about 500 nm thick. The etching step is performed after the rinsing is stopped for a while and the pressure of the chamber to be treated is lowered, wherein chlorine is introduced into the processing chamber at a temperature of about 950 °C. The chamber pressure during this time was 100 mbar.

After stopping the rinsing for a period of time, an AlN layer was deposited again by introducing TMAl and NH ₃ under a lower processing chamber pressure and a GaN layer was deposited again by introducing TMGa and NH ₃ . Here, the layer thickness of AlN is about 30 nm or less, for example 10 nm, and the layer thickness of GaN is about 500 nm or less, for example, 150 nm.

After the rinsing is stopped for a while, an etching step is performed in which Cl _{2 is} introduced into the processing chamber.

Finally, a tempering step is carried out in which only H ₂ and NH _{3 are} introduced into the treatment chamber.

The III-V coating step and the subsequent etching step can be carried out sequentially as a sequence of processing steps until the SiN coating is removed without residue.

In an unillustrated embodiment, it is only necessary to wet the SiN coating of the carbonized niobium processing chamber wall with liquid aluminum and introduce Cl ₂ into the processing chamber immediately after the wetting step to complete the cleaning of the processing chamber or III. - deposition of the VI family layer. The sequence of cleaning steps can also be performed cyclically and repeatedly, wherein each step sequence includes a wetting step and an etching step.

All the revealed features (ie, themselves) are the essence of the invention. Therefore, the disclosure of the present application also contains all the contents disclosed in the related/attached priority file (copy of the prior application), and the features described in the files are also included in the scope of the patent application of the present application. The sub-items illustrate the features of the prior art improvements of the prior art using optional side-by-side wording, the main purpose of which is to make a divisional application on the basis of the claims.

Claims (11)

A method for removing deposits from a wall/surface of a processing chamber of a CVD reactor, particularly from a surface of a coated SiC graphite, wherein the processing chamber is heated to a cleaning temperature and introduced into the processing chamber for a period of cleaning time A cleaning gas for the VII main group element, characterized in that the wall/surface waiting to be cleaned is wetted with metal before introduction of the cleaning gas. The method of claim 1 characterized in that the walls/surfaces are wetted with Al, Ga or In or, in other words, other elements of the third main group to specifically remove the SiN coating. The method of claim 1, characterized in that a combination of chlorine gas and an inert gas such as a rare gas or nitrogen is used as the cleaning gas. The method of claim 1, wherein the cleaning temperature is in the range of 500 ° C to 1200 ° C during wetting and/or etching. The method of claim 1, wherein a III-V layer is deposited on the wall/surface waiting to be cleaned after wetting, before introducing the cleaning gas, wherein the III-V layer is specifically referred to as AlN , GaN or other nitrites (Nitrit). The method of claim 1, characterized in that after the wetting of the walls/surfaces, a sequence of processing steps is performed in turn, comprising at least one processing step of depositing a III-V layer on the walls/surfaces and The processing step of introducing the cleaning gas into the processing chamber. The method of claim 1, characterized in that the sequence of processing steps is repeated in turn, comprising at least one processing step of wetting the walls/surfaces of the processing chamber with metal and introducing a cleaning gas into the processing chamber. Processing steps. The method of claim 1, wherein the effect of wetting the walls of the processing chamber with a metal is obtained by introducing an organometallic compound into the processing chamber along with a carrier gas. The method of claim 1, wherein the temperature in the processing chamber continuously rises during wetting. The method of claim 1, wherein the walls are wetted with at least one of the metal closures. The method of claim 1, wherein the group III-V layer deposited on the wetted surface is a layer sequence composed of different layers, wherein it is specified that the first layer is AlN and the second layer is GaN.