JPH0533811B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a cold-wall method for highly uniform deposition of specific elements or compounds onto a workpiece.
This invention relates to an improved chemical vapor deposition apparatus of the wall) type.

BACKGROUND OF THE INVENTION Chemical vapor deposition (CVD) refers to the process of depositing solid materials from a gaseous phase onto a substrate by a chemical reaction. Deposition reactions generally include thermal decomposition, chemical oxidation, or chemical reduction. As an example of pyrolysis,
The organometallic compound is transported as a vapor onto the substrate surface where it is reduced to its elemental metal state.

In the case of chemical oxidation, hydrogen is usually used as reducing agent, and metal vapors are also used. The substrate functions as a reductant. For example, in the case of tungsten hexafluoride reduction with silicon. The substrate also functions as an element of a compound or alloy. CVD processes can be used to deposit compounds and alloys such as oxides, nitrides and carbides or many elements.

In the present invention, by using CVD techniques, substrates can be deposited for various purposes. Applications of the invention include tungsten carbide and aluminum coatings on cutting tools; corrosion-resistant coatings such as tantalum, boron nitride, silicon carbide, etc.; and tungsten anti-corrosion coatings on steel. Furthermore, the apparatus of the invention is particularly useful for the production of solid state electronic devices and energy conversion devices.

Chemical vapor deposition of electronic materials is described in the following publications:

TLChu et al, J.Bac.Sci.Technol.10, 1
(1973); BEWatts, Thin Solid Films 18, 1
(1973) These documents describe the doping and formation of epitaxial films of materials such as silicon, germanium, and gallium arsenide. In the energy conversion literature, CVD processes are used to retain fission products;
Materials for solar energy harvesting and superconductivity are provided. An overview of chemical vapor deposition can be found in the following documents:

WABryant, “The Fundamentals of
Chemical Vapor Deposition”in Journal of
Materials Science 12, 1285 (1977) Deposition parameters such as temperature, pressure, reactant gas proportions, and gas flow volume and distribution determine the deposition rate and capacity of a particular device, which in turn determines the uniformity and quality of the deposition. . Conventional equipment has been limited in its ability to control these parameters due to contaminant build-up.

There are two types of reaction chambers for CVD: cold wall type and hot wall type (hot wall type).
It can be roughly divided into two types: wall). In the case of cold wall type,
The substrate is heated by inductive coupling, radiant heating or direct electrical heating of internal support elements. Thermal wall type relies on radiant heating elements arranged to heat the reaction and deposition areas.

A cold wall device for CVD is disclosed in US Pat. No. 3,594,227,
No. 3699298 and No. 3916822. In these devices, a semiconductor wafer is placed inside a vacuum chamber, and an induction coil is placed outside the chamber. The wafer is attached to an inductive material suitable for heating with RF energy. By localizing the heating to the area near the semiconductor wafer, CVD is confined to that heated area.
Since the unheated wall is below the CVD temperature,
Deposition on walls is reduced. The temperature within the reaction zone is not uniform compared to hot wall devices and it is not possible to control the temperature for individual wafers.

One object of the present invention is to provide a cold wall CVD apparatus that can accurately control the temperature of individual wafers.

Another objective is to provide a CVD device that minimizes particle formation and is self-cleaning.

Another object is to provide a CVD device whose operation is automated and controlled by a computer.

Another object is to provide a CVD apparatus with uniform gas mixing and uniform gas flow across the wafer.

SUMMARY OF THE INVENTION The above objects are achieved by the following apparatus according to the invention. A cold wall CVD device has a separate mixing chamber. Gases from several injection rings with many small holes are mixed. A water-cooled baffle is used to promote mixing and pass the ring-shaped mixed gas stream into the deposition chamber.

Multiple independently adjustable exhaust ports are provided to adjust the symmetry of gas flow within the reaction chamber.

Wafers held downward by the chuck are coated one at a time. The chuck can heat the wafer to 950°C. The downward positioning minimizes wafer damage from particles. Wafers are transferred between cassettes through load locks by automated computer-controlled handling equipment. The handling device is removed before closing the load lock. This eliminates the need for belts and sliding surfaces, reducing particle generation. Also,
Vapor deposition on handling equipment is also eliminated.

A wafer for deposition is held against a chuck that can be heated by radiation. The chuck is also capable of operating in plasma enhanced mode. Plasma can also be used to clean the chamber after wafer removal, minimizing downtime.

The CVD device according to the present invention includes VLSI and
It is also applicable to various deposition processes for ULSI. Applications include, for example, doped and undoped polysilicon, refractory metal silicates, refractory metals, thermal nitrides, plasma nitrides, plasma oxides, thermal oxides, fluorosilicate glasses, and borofluorosilicate glasses. Conceivable. The formed film has good uniformity, with low particle density and excellent uniformity of deposited thickness. The features of the present invention will become clearer from the following description.

[Description of Preferred Embodiments] Preferred embodiments of the present invention will be described with reference to the drawings. Identical parts are given the same reference numerals throughout the figures. FIG. 1 shows an overall diagram of a chemical vapor deposition (CVD) apparatus 10 according to the present invention. Frame 12 supports wafer load apparatus 14, deposition chamber 16, gas mixing chamber 18, and exhaust manifold 46.

1 in cold-wall type CVD equipment
One mode of operation is to introduce two different reactant gases. These gases must be thoroughly mixed before impinging on the heated workpiece. Gas mixing chamber 1 separate from the deposition chamber
8 is used to control gas mixing before deposition.
The two gases enter the mixing chamber 18 through a pipe in the form of an upper ring 20 and a lower ring 22.
be introduced within. Each lead-in ring 20, 22
The rings are hollow and have approximately 100 7/1000 inch diameter holes to facilitate the passage of gas and for injection of gas from each ring into the mixing chamber 18. The mixed buttful 24 is a stuffing gland with an O-ring 28.
26 in the vertical direction for optimal mixing adjustment. The mixing buttful 24 is the shaft 34
It has coaxial channels 30, 32 therein and a circular ring channel 36 in the top plate 38 for circulating cooling water. Vapor deposition chamber 16
has water cooling channels 17 inside the outer wall to reduce reactions in the outer wall.

Exhaust pipe 4 leading to exhaust manifold 46 to facilitate uniformity of vapor deposition coverage of the workpiece.
Three outlets with 0, 42, 44 are used to evacuate the steam chamber 16. As shown in FIGS. 4-7, the manifold 46 includes pipes 40, 42, 4
4 and the central chamber 5
and a cylindrical inner shell 50 with an opening 52 to 4. Three independently adjustable shutters 56 having semicircular apertures 58 are used to adjust the exhaust air from each of the three apertures. Each of the three shutters 56 has an outer shell 48 and an inner shell 50.
and a set screw (not shown)
It can be fixed by Central chamber 5
4 communicates through a pipe 60 with an exhaust system (not shown).

Deposition chamber 16 is separated from cassette chamber 62 by a load lock 64. In operation, a cassette 61 of wafers is inserted into the cassette chamber 62 and
is sealed and evacuated. Cassette 61 is positioned by cassette elevator 66. Manipulator arm 68 slides blade 70 beneath wafer 63. The blade 70 with the wafer is then pulled out from the cassette 61. Manipulator arm 68, driven by motor 69, then rotates blade 70 through 90 degrees. The load lock 64 opens and the manipulator arm 6
8 extends and carries the blade 70 with the wafer 63 into the center of the deposition chamber 16. Two ceramic fingers 7 each attached to a support 71
Three lifting arms 72 with 4 contacts the back side of wafer 63 by chuck 76 (wafer surface facing down) and lift wafer 63 from the blade. Since there are six ceramic fingers in total, there is no need to preorient the wafer horizontally. The chuck 76 is a hollow assembly having a metal face 78, a stainless steel wall 80, a metal back ring 82 with water cooling channels 84, and a quartz back plate 86.
has. A chuck 76 extends into the deposition chamber 16 away from the top of the chamber 16 to promote uniformity of gas flow over the wafer. Metal screen 88 attached to metal support structure 90
is grounded to the wall of deposition chamber 16 to maintain RF power within chuck 76. Check 7
6 is filled with 1-10 Torr helium. The helium exits through three small holes 92 approximately 7/1000ths of an inch from the center of metal surface 78 . A pattern of six radial grooves and a circumferential groove 96 approximately 90/1000ths of an inch in diameter is used to direct heated helium to the backside of the wafer to provide thermal contact.
A water-cooled array of six 1000W tungsten-halogen lamps illuminates the quarterback plate 8.
6, the chuck 76 is heated. These lamps can be used individually or in combination to control heating.

The lamps are oriented along the inner edge of the chuck to provide uniform heating. A sensor on chuck 76 detects temperature. The detected temperature is sent to a central computer 110. Computer 110 controls the lamp and controls the temperature. The temperature of the wafer is controlled within 1°C between 150°C and 950°C.

The chuck 76 can also operate in a thermal enhancement mode or a plasma enhancement mode or a combination thereof. The metal surface 78 of chuck 76 is insulated from ground by ceramic sidewalls 80 to maintain the RF potential supplied by cable means (not shown). A power level of about 100 W is sufficient to increase deposition on the wafer surface. Supply line 100 for supplying helium to chuck 76 should be made of insulating material. A small piece of gauze is inserted into the supply line 100 to prevent the plasma from spreading into the supply line 100. A dark space shield 102 is used on the side of the chuck 76 to prevent external plasma along the sidewalls of the chuck 76. A dark space shield 73 is also used on the ceramic finger 74 to prevent plating that would compromise the insulating properties of the ceramic.

Plasma can be used to clean the deposition chamber 16, minimizing downtime for cleaning. After removing the wafer,
Increase the RF power from a deposition level of about 100W to about 1000W. To increase the rate of purification, use NF ₃ or
Etch gas of CF ₄ may be introduced at approximately 200 mTorr. At this power level, the plasma spreads and cleans the entire deposition chamber 16.

The walls of the deposition chamber 16 are water cooled to prevent gas phase reactions and to prevent deposition on the chamber walls. Deposition of chamber walls has the undesirable result of particulate contamination. Chamber walls can be made of aluminum or stainless steel. Aluminum is a good chamber material for the deposition of oxides, nitrides, polysilicon, refractory metals, and refractory metal silicides. Stainless steel is more suitable for other materials that require a chlorine process.

As shown in FIG. 9, all equipment is controlled by a central computer 110. computer 1
10 is a wafer loader 14 and various valves 11
Exhaust system 11 with 4,116,118
2 and load lock 64. At the appropriate time, computer 110 turns on heat lamp 98, RF
Power supply 120 and mass flow controller 1
Turn on 22 and introduce gas.

Although specific embodiments have been described, the present invention is not limited thereto, and many modifications and improvements can be made without departing from the scope of the present invention as set forth in the claims.

[Brief explanation of the drawing]

FIG. 1 is a front view of a CVD apparatus that is an embodiment of the present invention. FIG. 2 is a partial cross-sectional view of the device of FIG. 1. FIG. 3 is a cross-sectional view taken along line 3--3 in FIG. 2, showing the side of the chuck. FIG. 4 is a cross-sectional view taken along line 4--4 in FIG. FIG. 5 is a sectional view taken along line 5--5 in FIG. 4. Figure 6 is 6 in Figure 5.
FIG. 6 is a cross-sectional view taken along line -6. Figure 7 shows
7 is a diagram showing the shutter of FIGS. 5 and 6. FIG. FIG. 8 is a plan view of the wafer manipulator shown in FIG. 2. FIG. 9 is a block diagram of the apparatus of FIG. Explanation of main symbols, 12... Frame, 14... Load device, 16... Vapor deposition chamber, 17... Water cooling channel, 18... Mixing chamber, 20, 22... Ring, 24... Mixing buttful, 26... Stuffing gland, 28... O Ring, 30, 32... Coaxial channel, 34... Shaft, 36... Circular ring channel, 38... Top plate, 40, 42, 44...
Exhaust pipe, 46...Exhaust manifold, 48...Outer shell, 50...Inner shell, 54...Central chamber, 56...Shutter, 60...Pipe, 61...Cassette, 62...Cassette chamber, 63...Wafer, 66...Cassette Elevator, 68... Manipulator arm, 69... Motor, 70... Blade,
72...Lifting arm, 73...Dark space shield, 74...Ceramic finger, 76...Chuck, 78...Metal surface, 80...Stainless steel wall, 82...Back ring, 84...Water cooling channel, 86...Back plate, 88 ... Metal screen, 92 ... Hole, 96 ... Circumferential groove, 98 ... Heat lamp, 100 ... Supply line, 102 ... Dark space shield, 110 ... Computer, 114, 116, 1
18... Valve, 120... RF power supply, 122... Mass flow controller.

Claims (1)

[Claims] 1. An apparatus for chemical vapor deposition on a workpiece, comprising the following means and features: a vapor deposition reaction chamber; a gas mixing chamber communicating with the vapor deposition reaction chamber; a means for evacuation of the vapor deposition reaction chamber; connection means for connecting the gas mixing chamber; gas supply means for introducing gas into the gas mixing chamber; and connecting means for connecting the gas mixing chamber and the vapor deposition chamber for controlling the flow of gas from the gas mixing chamber to the vapor deposition reaction chamber. adjustable buffling means between the reaction chamber and the deposition chamber, the buffling means comprising a generally flat, thin body attached near the center to an elongated support; chuck means for controlling; and wafer holding means for holding a workpiece relative to said chuck means. 2. The device according to claim 1, wherein: the adjustable baffle means is cooled by a fluid flowing within the baffle. 3. Apparatus according to claim 2, wherein: the adjustable buffling means comprises a disk mounted on a support. 4. The device according to claim 1, wherein: the gas supply means includes at least one hollow pipe formed in a ring shape with a large number of small holes. 5. The device according to claim 4, wherein: the gas supply means includes at least two closely spaced hollow pipes each having a large number of small holes and formed in a ring shape; Device. 6. The apparatus of claim 1, wherein: the connecting means includes at least three outlets in the vapor deposition reaction chamber; each outlet having a A device having shutter means; 7. Apparatus as claimed in claim 1, wherein the chuck means includes means for flowing gas behind the workpiece for thermal contact between the chuck and the workpiece. including; equipment. 8. An apparatus as claimed in claim 7, further comprising: means for radiant heating of the chuck means. 9. Apparatus according to claim 7, wherein: the chuck means includes means for supporting a plasma discharge on the surface of the workpiece in contact therewith. 10. The apparatus according to claim 9, further comprising: means for radiant heating the chuck means. 11. The apparatus according to claim 10, wherein: the wafer holding means includes a number of ceramic fingers that support the workpiece from below. 12. The device according to claim 3, wherein: the gas supply means includes at least two closely spaced hollow pipes each having a large number of small holes and formed in a ring shape; equipment. 13. The apparatus of claim 12, wherein: the chuck means includes means for flowing gas behind the workpiece for thermal contact. 14. The apparatus according to claim 13, further comprising: means for radiant heating the chuck means. 15. The apparatus of claim 14, wherein: the chuck means includes means for supporting a plasma discharge on the surface of the workpiece in contact therewith. 16. The apparatus of claim 14, further comprising: means for plasma cleaning the apparatus. 17. The apparatus of claim 14, further comprising: means for reactive ion cleaning of the apparatus. 18 Apparatus for chemical vapor deposition on a workpiece, comprising the following means and features: a deposition reaction chamber having walls cooled by an internally circulating fluid; a gas mixing chamber communicating with the deposition reaction chamber; connecting means for connecting a vacuum evacuation means to the vapor deposition reaction chamber, said vapor deposition reaction chamber comprising at least three outlets, each of said outlets having shutter means for independently regulating the flow therethrough; connection means; gas supply means for introducing gas into the gas mixing chamber, the gas supply means comprising at least two closely spaced hollow pipes each formed in the form of a ring with a number of small holes; adjustable buffling means between the gas mixing chamber and the deposition reaction chamber for controlling the flow of gas from the gas mixing chamber to the deposition reaction chamber, the means being cooled by a fluid flowing therethrough; Buffling means comprising a disk mounted on a support; chuck means located within the deposition reaction chamber for controlling the temperature of the workpiece, the buffling means comprising a disk mounted on a support; chuck means comprising: means for radiantly heating the chuck means; and means for supporting a plasma discharge on a surface of a workpiece in contact with the chuck means; A holding means for holding a workpiece against a workpiece, the holding means including a plurality of ceramic fingers supporting the workpiece from below. 19. The apparatus of claim 18, further comprising: means for plasma cleaning the apparatus. 20. The apparatus of claim 18, further comprising: means for reactive ion cleaning of the apparatus. 21. Apparatus for chemical vapor deposition on a workpiece, comprising the following means and features: a vapor deposition reaction chamber; a gas mixing chamber located below and communicating with the vapor deposition reaction chamber; said gas mixing chamber buffling means between said gas mixing chamber and said deposition reaction chamber for controlling the flow of gas from said gas mixing chamber to said deposition reaction chamber; and such that the surface of said workpiece receiving deposition faces downward. Wafer holding means located within the deposition reaction chamber for holding the workpiece. 22. The apparatus according to claim 23, further comprising: means for heating the workpiece. 23. The apparatus according to claim 24, further comprising: means for applying an RF bias to the workpiece. 24. Apparatus for chemical vapor deposition on a workpiece, comprising the following means and features: a deposition reaction chamber; a gas mixing chamber located below and communicating with the deposition reaction chamber; and the workpiece. Wafer holding means located within the deposition reaction chamber for holding the workpiece so that the surface on which the object is deposited faces downward. 25. The apparatus according to claim 24, further comprising: means for heating the workpiece. 26. The apparatus according to claim 25, further comprising: means for applying an RF bias to the workpiece.