Patent Application
20050287813
The present application claims priority from Japanese Application JP 2004-190888 filed on Jun. 29, 2004, the content of which is hereby incorporated by reference into this application.
1. Field of the Invention
The present invention relates to a manufacturing apparatus for semiconductor devices and a manufacturing apparatus for semiconductor lasers and, more in particular, it relates to a manufacturing apparatus for semiconductor devices or semiconductor lasers capable of removing fabrication damages, for example, to wafers if any in a plasma process of semiconductor device manufacturing steps thereby decreasing undesired effects on devices and improving the yield and the reliability of products.
2. Description of the Related Art
The manufacturing steps for semiconductor devices include those steps, for example, a plasma process such as plasma etching and plasma CVD that damage wafers during fabrication and tend to cause destruction and degradation of devices.
For example, referring to the outline for a method of manufacturing a high electron mobility transistor (HEMT) having a recessed structure, an AlGaAs buffer layer, an InGaAs channel layer, a GaAs cap layer and an SiO2 film are formed successively on a semi-insulative GaAs substrate. Then, the SiO2 film is bored to form a burying recess. A gate metal is deposited to form a T-type gate of a predetermined shape and a photoresist is formed into a wide recess pattern. Then, a gate electrode can be formed by etching the GaAs cap layer and the InGaAs channel layer in the shape of a wide recess pattern. This manufacturing method is disclosed by Japanese Patent Laid-open No. H11-150125.
In this case, a plasma process is utilized for the deposition or etching of the SiO2 film. That is, a plasma enhanced chemical vapor deposition process (p-CVD) using, for example, an SiH4 gas, an N2O gas or the like can be used for the deposition of the SiO2 film, a reactive ion etching method (RIE) using, for example, a fluoric gas such as CF4 can be used for the etching of the SiO2 film, and a dry etching method using a gas containing halogen atoms such as fluorine atoms or chlorine atoms can be utilized for the etching of the semiconductor layer.
In the etching process of a metal film, an insulating film or a semiconductor by utilizing the plasma, and a thin film forming process by a sputtering method or a CVD method utilizing plasma, a phenomenon in which ions or radicals are implanted into a substrate is caused due to the potential difference between the plasmas and the specimen. Implanted ions or radicals lower the carrier density by the inactivation of carriers, increase of resistance by diffusion of impurities, formation of non-emissive recombination center, etc. to deteriorate electrical characteristics or lower the reliability of the device.
An object of the present invention is to provide a manufacturing apparatus for a semiconductor device with less deterioration of characteristics and having good reliability by the recovery from undesired deterioration of characteristics, that is, plasma damages caused in the process using plasmas.
The subject described above can be solved by applying a surface treatment of applying at least one of X-rays and UV-rays to plasma-exposed surface during or after the process utilizing the plasma.
Plasma-induced damage is caused by the intrusion of impurity atoms such as oxygen and fluorine into semiconductor crystals. By the bonding of the impurity atoms with dopants, the dopants are compensated to lower the carrier density and deteriorate the device characteristics. In this case, the impurity ions are generally ionized into negative ions and have ionic bonds. It has been generally known that photoelectrons are emitted when X-rays and UV-rays are applied to a substance. The present inventors have found that when X-rays and UV-rays are applied to the ionized impurity atoms to emit photoelectrons, the impurity atoms become electrically neutral, are dissociated from the bonding with the dopants, suspended in the inter-lattice space, and detached from the crystals when they reach the crystal surface.
More specifically, the object described above can be achieved in accordance with an aspect of the present invention by a method of manufacturing a semiconductor device of etching a work formed on a semiconductor substrate or depositing a metal film or an insulating film on a semiconductor substrate by using plasma, which method comprises conducting etching or deposition by using the plasmas and then irradiating the semiconductor substrate at least one of X-rays and UV-rays in a vacuum or in an inert gas atmosphere.
Further, the object of the invention can be attained by a semiconductor manufacturing apparatus according to another aspect of the invention comprising a processing chamber for etching a work formed on a semiconductor substrate or forming a film on a semiconductor substrate, and a surface treating chamber of irradiating the semiconductor substrate with at least one of X-rays and UV-rays in a vacuum or in an inert gas atmosphere, in which the semiconductor substrate is transported from the processing chamber to the surface treatment chamber and the irradiation is controlled in the surface treatment chamber.
Further, the object of the invention can be attained by a semiconductor manufacturing apparatus according to another aspect of the invention comprising a holding section for holding a semiconductor substrate, and an irradiation section for irradiation of at least one of X-rays and UV-rays, in which the inside of the holding section and the inside of the irradiation section are kept in a vacuum or in an inert gas atmosphere, and in which a semiconductor substrate after etching of a work formed on the semiconductor substrate or after deposition of a metal film or an insulating film on the semiconductor substrate is held in the holding section and the semiconductor substrate is irradiated with at least one of X-rays and UV-rays from the irradiation section.
The invention can remove impurity elements intruded into the crystals caused by the plasma process by irradiation of X-rays and irradiation of UV-rays thereby suppressing lowering of the carrier density and can contribute to improvement of the quality and productivity of devices.
Preferred embodiments of the present invention will be described in details based on the drawings, wherein:
Preferred embodiments of the present invention are to be described with reference to the drawings.
For the X-ray source, those X-ray targets used generally for the application use of X-ray diffraction, X-ray photoelectron spectroscopy, X-ray fluorescence analysis and X-ray illumination such as Mg, Al, Fe, Cr, Cu, Mo, W and Y can be utilized. A rotary target may also be used in order to increase the X-ray power. X-rays emitted from the X-ray source may be directly applied to specimens. Alternatively, as shown in
In this apparatus, an SiO2 film is etched by using a CF4 gas in the insulating film etching chamber 12 for instance and then the specimens are transported in a vacuum to the surface treatment chamber 16 and X-rays can be applied thereto. This can dissociate and remove fluorine atoms intruded in the crystals upon etching of the SiO2 film. While the SiO2 film is shown as an example of the insulating film, it will be apparent that other insulating films, for example, Al2O3, AlN, TiO2, SiN films, etc. can also be treated quite in the same manner.
In the same manner, the GaAs surface is etched by using a hydrogen chloride gas in the semiconductor etching chamber 13 and then is irradiated with UV-rays in the surface treatment chamber 16, whereby chlorine atoms intruding in the crystals can be removed. While GaAs is shown as an example of the semiconductor, other semiconductors, for example, Si, SiC, SiGe, AlGaAs, InGaAsP, InGaP, InAlP, InGaAlAsP, InGaAs, InAlAs can also be treated quite in the same manner.
When the insulating film is formed in the insulating film deposition chamber 14, oxygen contained in the film deposition gas or fluorine remaining in the residual atmosphere may sometimes intrude into crystals. In this case, after film deposition, intruded impurity atoms such as oxygen or fluorine are irradiated with X-rays in the surface treatment chamber 16 for removal.
In a case of ashing resists or carbides left on the surface after etching in the ashing chamber 15 by using an oxygen gas and removing them, oxygen is sometimes implanted into crystals. Further, in a case of ashing and removing the insulating film by using a CF4 gas, fluorine may sometimes intrude into the crystals. Also in these cases, after the ashing processing, intruded impurity atoms can be irradiated with X-rays or UV-rays for removal in the surface treatment chamber 16.
Although not illustrated, also after the process of etching metal films or electroconductive films comprising, for example, Al, Ti, Mo, W, WSi and WSiN by using C2F6, fluorine atoms intruded into the crystals can be dissociated and removed by irradiation of X-rays in the same manner as described above. While CH4, HCl or C2F6 is used as the gas, similar effects can also be obtained in a case of using other fluorine-containing gases or halogen element-containing gases, for example, CHF3, SF6, HBr or HI.
This embodiment shows a case of applying the invention to a multi-chamber type processing apparatus having a plurality of functions, but it will be apparent that same effects can also be obtained by applying the invention to a single function type apparatus such as an etching apparatus or film deposition apparatus as shown in
Explanations for references in the drawings of the application are as below.
11 . . . load lock chamber, 12 . . . insulating film etching chamber, 13 . . . semiconductor etching chamber, 14 . . . insulating film deposition chamber, 15 . . . ashing chamber, 16 . . . surface treatment chamber for irradiation of X-rays or UV-rays 17 . . . transport chamber, 21 . . . load lock chamber, 22 . . . processing chamber for conducting processing such as etching or film deposition, 23 . . . surface treatment chamber for irradiation of X-rays or UV-rays, 31 . . . surface treatment chamber attached to the insulating film etching chamber for irradiation of X-rays and UV-rays, 32 . . . surface treatment chamber attached to the semiconductor film etching chamber for irradiation of X-rays or UV-rays, 41, 43, 61, 62 . . . X-ray source or a UV-ray source, or radiation source comprising an X-ray source and a UV-ray source, 42 . . . specimen, 51 . . . X-ray target, 52 . . . electron beam source, 53 . . . high-speed electron beam, 54 . . . X-rays emitted from X-ray target, 55 . . . X-ray waveguide tube bundle, 56 . . . X-ray arranged in parallel or bundled, 63 . . . specimen case storing shelf, 64 . . . specimen case, 65 . . . specimen case transporting manipulator, 66 . . . specimen storage housing main body, 67 . . . specimen access port, 68 . . . X-ray shielding body.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2004-190888 | Jun 2004 | JP | national |
