GB2112205A - A thermal processing system for semiconductors and other materials using two or more electron beams - Google Patents
A thermal processing system for semiconductors and other materials using two or more electron beams Download PDFInfo
- Publication number
- GB2112205A GB2112205A GB08222309A GB8222309A GB2112205A GB 2112205 A GB2112205 A GB 2112205A GB 08222309 A GB08222309 A GB 08222309A GB 8222309 A GB8222309 A GB 8222309A GB 2112205 A GB2112205 A GB 2112205A
- Authority
- GB
- United Kingdom
- Prior art keywords
- workpiece
- wafer
- temperature
- electron beams
- heated
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
Links
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
- H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
- H01L21/04—Manufacture or treatment of semiconductor devices or of parts thereof the devices having at least one potential-jump barrier or surface barrier, e.g. PN junction, depletion layer or carrier concentration layer
- H01L21/18—Manufacture or treatment of semiconductor devices or of parts thereof the devices having at least one potential-jump barrier or surface barrier, e.g. PN junction, depletion layer or carrier concentration layer the devices having semiconductor bodies comprising elements of Group IV of the Periodic System or AIIIBV compounds with or without impurities, e.g. doping materials
- H01L21/26—Bombardment with radiation
- H01L21/263—Bombardment with radiation with high-energy radiation
- H01L21/2636—Bombardment with radiation with high-energy radiation for heating, e.g. electron beam heating
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J37/00—Discharge tubes with provision for introducing objects or material to be exposed to the discharge, e.g. for the purpose of examination or processing thereof
- H01J37/30—Electron-beam or ion-beam tubes for localised treatment of objects
- H01J37/317—Electron-beam or ion-beam tubes for localised treatment of objects for changing properties of the objects or for applying thin layers thereon, e.g. for ion implantation
Abstract
In apparatus and methods for thermal processing of semiconductors and other materials in order to change their properties, two electron beams are directed from opposite sides of e.g. a silicon wafer which is thermally isolated as far as possible. By combining the heating effects of the two beams the temperature distribution that is required to modify the wafer is achieved. In one embodiment, one beam is scanned rapidly in a raster over the whole wafer to heat it while the second beam is formed into a line and scanned to provide further heating. This combination is used to modify a poly-crystalline silicon film into single crystal material. In other embodiments the second beam is formed into a spot a square or other shape to obtain the desired temperature distribution. <IMAGE>
Description
SPECIFICATION
A thermal processing system for semiconductors and other materials using two or more electron beams
Field of invention
This invention relates to apparatus and methods for heating materials rapidly to high temperatures in a highly controlled manner in order to modify their properties. It has particular application in the manufacture and processing of semiconductor materials and devices.
Background of invention
A workpiece in this context is usually a semiconductor (silicon) wafer or chip which is often in the form of a thin disc about 0.4 mm thick and 75 mm diameter. In the fabrication of devices this workpiece may be implanted with ions or it may have films of oxide or polycrystalline silicon fabricated on it. These films are usually around a few microns thick. Such workpieces are subject to one or more heat treatments in furnaces at temperatures around 1 0000C during the process of manufacturing devices in them.
Designers of integrated circuits are aware that it is difficult to insulate devices from each other when they are made in silicon crystals. The usual method is to use reverse biased p-n junctions for separating devices electrically To overcome the limitations of this method silicon films on sapphire are used to make devices such that sapphire acts as the insulator between devices.
The invention described here has inter alia, the capacity to make crystalline silicon film on an insulator which gives many advantages to the integrated circuit manufacturer and in particular the possibility of isolating devices from each other by using the insulating film on which the crystalline silicon film is made.
The invention
The invention consists of a holder which supports a wafer in such a way that both faces of the wafer are accessible to the electron beams.
The wafer is held so that the area of contact with the holder is small and thereby heat losses by conduction from it are minimised.
There are means for generating two electron beams. One electron beam, the first or lower electron beam strikes the lower surface of the wafer. The other electron beam, the second or upper beam, strikes the upper surface of the wafer.
The lower electron beam is scanned rapidly in a raster so that the whole of the wafer absorbs energy from the beam in a controlled and uniform manner. The scanning conditions ensure that the power density delivered is effectively given by beam power divided by scanned area. The energy absorbed by the wafer causes its temperature to rise rapidly to a desired value.
The second beam is formed into a line in one embodiment of the invention. The line beam strikes the surface of the wafer and is scanned
across it either by deflecting the line
(electromagnetically or electrostatically) or by
moving the wafer underneath the line which
remains stationary.
In another embodiment the beam is formed
into a circular or square shape and deflected over the surface. In further embodiments the beam is formed into a curve shaped like a boomerang. In
principle many shapes are possible for the upper beam.
The invention is used for several purposes in the processing of semiconductor materials. Some examples illustrate the applications that have been carried out so far.
Polycrystalline silicon films have been deposited by chemical vapour deposition on oxide grown on silicon wafers and the polysilicon film is in contact with the single crystal silicon substrate through trenches in the oxide film. The whole surface is covered by another oxide film. These layers have been processed by the dual beam invention so that while the lower beam heats the wafer the upper line beam recrystallises the polysilicon when it is deflected over the upper wafer surface.
Ion implanted semiconductors have been heated from the back to a temperature below that required for the removal of ion implantation damage. Specific regions have been annealed through local heating above this temperature induced by the second beam.
Detailed description of drawing
(a) One embodiment of the two beam system is illustrated in Figure 1(a). The workpiece (10) is mounted in thermal isolation and so that both faces are accessible to electron beams. The first beam (20) derived from a source (21) is scanned over the surface of the workpiece by a deflection system (22). This closely achieves uniform energy deposition over the workpiece, with a mean power density of the beam power divided by scanned area. The beam is scanned with perpendicular deflection coils, excited by triangular waveforms of asynchronous frequencies over an area larger than the workpiece.
The second beam, (30), is a spot, of area small compared to the size of the workpiece. This spot emanates from a source (31), and moved over the whole or part of the workpiece by a deflection system (32). Further relative movement between spot and workpiece is obtained through a mechanically movable stage (1 1). With mechanical movement of the stage, arrangements may be made to move the lower beam in synchronism.
The second beam heats the region underneath the beam, to a temperature above the average temperature of the workpiece which depends on the power and size of the beam, and the material properties of the workpiece. Changes in the properties of the workpiece may be effected without melting, or by melting the region adjoining the upper beam.
(b) Equipment as in (a) as regards workpiece and first beam, but with a line beam (40), which can be of any length relative to the workpiece.
The line beam is generated by a source (41) and may be deflected by a deflection system (42) or the stage (11) may be moved under the beam.
The region under the line is heated above the average workpiece temperature, to a temperature which may be above or below the melting point of the workpiece.
(c) Further combinations include workpiece and first beam as in (a), but with a chevron beam, circular beam, curved beam of any shape or synthesized beam by rapid scanning. In addition, the first beam may be shaped to obtain more complex basic workpiece heat patterns.
Claims (8)
1. Apparatus for effecting changes in a workpiece by thermal means using two or more electron beams. The invention comprises of a means for generating a first electron beam - a means for deflecting this beam over one face
of a workpiece such as a wafer or
semiconductor and getting uniform energy
deposition or predetermined heat pattern (in
the preferred embodiment the wafer is heated
uniformly), ~an arrangement for mounting the workpiece in
approximately thermal isolation so that heat
loss is largely by radiation and both faces are
accessible to electron beams, - a means for generating a second beam which
is directed towards the workpiece but on its
opposite face, i-- a means for forming a second beam into a shape (spot or line or other shape) which is
used to provide a heat pattern or temperature
distribution which brings about a change in the
material properties of the workpiece.
2. Apparatus in claim 1 ensures that the second beam provides a temperature rise above the average temperature of the workpiece, in the region under the second beam.
3. Apparatus as in claim 1 in which the first beam is scanned in a raster so that the beam's energy is deposited effectively uniformly and the temperature of the whole workpiece rises to a predetermined level.
4. Apparatus as in claim 1 in which the second beam is formed in a spot or line, or circle or curve, or a chevron and deflected to heat a part of the workpiece so that desired temperature distribution is obtained.
5. Apparatus as in claim 1 has the workpiece in thermal isolation as far as possible by limiting contact points with the workpiece holder.
6. In the apparatus of claim 1 the workpiece is heated in one application so that the parts under the second beam are melted and allowed to recrystallise. For example a polycrystalline silicon film is melted while sandwiched between two oxide films and allowed to recrystallise into single crystal seeded from a silicon wafer.
7. In the apparatus of claim 1 the workpiece may have a CVD polysilicon film on silicon and be heated so that it recrystallises the polysilicon film.
8. In the apparatus of claim 1 the first beam heats ion implanted material and the second beam anneals it in specific regions by raising the temperature in that region above that required to remove the crystal damage.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB08222309A GB2112205A (en) | 1981-05-28 | 1982-05-26 | A thermal processing system for semiconductors and other materials using two or more electron beams |
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB8116335 | 1981-05-28 | ||
| GB08222309A GB2112205A (en) | 1981-05-28 | 1982-05-26 | A thermal processing system for semiconductors and other materials using two or more electron beams |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| GB2112205A true GB2112205A (en) | 1983-07-13 |
Family
ID=26279617
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB08222309A Withdrawn GB2112205A (en) | 1981-05-28 | 1982-05-26 | A thermal processing system for semiconductors and other materials using two or more electron beams |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB2112205A (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2153700A (en) * | 1984-01-27 | 1985-08-29 | Sony Corp | Crystal growth |
| EP1170773A1 (en) * | 2000-07-03 | 2002-01-09 | H.-P. Ehret | Coaxial laser and ECR ion beam source device and process for coating and/or implanting in matter and/or human or animal tissues |
| DE19900437B4 (en) * | 1999-01-11 | 2009-04-23 | Ehret, Hans-P. | Method and device for ion implantation in solids and / or for coating solid surfaces and the use of methods and apparatus |
-
1982
- 1982-05-26 GB GB08222309A patent/GB2112205A/en not_active Withdrawn
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2153700A (en) * | 1984-01-27 | 1985-08-29 | Sony Corp | Crystal growth |
| DE19900437B4 (en) * | 1999-01-11 | 2009-04-23 | Ehret, Hans-P. | Method and device for ion implantation in solids and / or for coating solid surfaces and the use of methods and apparatus |
| EP1170773A1 (en) * | 2000-07-03 | 2002-01-09 | H.-P. Ehret | Coaxial laser and ECR ion beam source device and process for coating and/or implanting in matter and/or human or animal tissues |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| WAP | Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1) |