Process gas supply apparatus

3 4

FIG. 5A is a view, showing a conventional bubbling An end portion of a liquid leading pipe 34 across which

method for vaporizing a liquid material into a process gas to a manual open-close valve V3 is provided is introduced into

be supplied; the liquid material 18 in the liquid container 20. Another end

FIG. SB is a view, showing a conventional baking method portion of the pipe 34 is located outside the liquid container

for vaporizing a liquid material into a process gas to be 5 20 and connected to the supply pipe line 22 via a joint 36.

supplied; and ^ SUppiy pjpe jjne 22 is formed of a steel pipe. Across

FIG. 5C is a view, showing a conventional direct vapor- the t j ^nc 22, an open-close valve Vll. an

ization method for vaporizing a liquid material into a open.ciose valve V4, liquid flow control means 42 for

process gas to be supplied. controlling the flow of the liquid material 18 flowing

DETAILED DESCRIPTION OF THE 10 through the line 22. an open-close valve V5. the vaporizing

I^^vTiNTTON means 26 and an open-close valve V6 are provided in the

The embodiments of the invention will be described with order mentioned between the upstream side and the downreference to the accompanying drawings. stream side with resPect t0 me flow of licluid material 18.

FIG. 1 shows a process gas supply apparatus 14 for „ ^ this stmcti^e. flie Uquid n^terM 18 flows in me state of

supplying a process gas to a process device 16 which forms 15 hfld uPstream of «ie vaporizing means 26. and m the state

a film. etc. on a treatment object such as a semiconductor °f Sas downstream of the vaporizing means 26. The liquid

wafer W w contra' means 42 is formed of a mass-flow controller

T .' . ,. ... . . .,. ... for liquids, or a micro pump which has a plurality of valve

In this embodiment, the process device 16 is a so-called u J- ■ J * 1 ^. ,i a c 1

. . „' r, ■ j • f • bodies therein and can accurately control the flow of only a

one-by-one type CVD film-forming device for processing ,n „ . . ,. .. 1 , . '

.' . 3r £ „, . 6 , . r„. & 20 small amount of a liquid (for example, even m the case of

semiconductor wafers W one by one. This device 16 forms „ , , „.., ^

. . • J * t -ar ■ a fl°w rate of about 0.5 CCM).

an aluminum film on a semiconductor wafer W using an'

organic aluminum metallic compound (DMAH in this The inner diameter of (hat portion of the supply pipe line embodiment). The process device 16 has a process container 22 which is located between the joint 36 and the vaporizing 90 made of e.g. aluminum. The process container 90 con- „ means 261S set t0 e 8-1/4 lnch- which ls sufficient to control tains a mount table 94 to be heated, for example, by a *e flow of a verv smaSi amount of u<mid and not to cause resistive heater 92. The mount table 94 holds thereon a wafer excessive pressure loss of the liquid material 18 flowing W by means of e.g. a mechanical clamp 96. The mechanical therethrough. Further, (he inner diameter of that portion of clamp 96 may be replaced with an electrostatic chuck. A the mPPfy P^ Une 22 which is located between the shower head 98 is provided in (he process container 90 30 vaporizing means 26 and the process device 16 is set to e.g. directly above the mount table 94. The shower head 98 is v«01 % inch-which enables a Process 8as t0 flow easUy witn connected to a process gas supply pipe line 22 incorporated a low fluid resistance. The inner wall surface of the supply in the process gas supply device 14 which will be described P1!*5 line 22 is beforehand electrolytically polished to reduce later. Exhaust vents 100 connected to a vacuum pump (not ^ amount of adhesion of moisture, etc. thereto and thereby shown) are provided in the bottom of the process container 35 Prevent unnecessary chemical reaction with DMAH. 90 such that gases in the container 90 can be exhausted. The vaporizing means 26 is connected, via a carrier gas The process gas supply device 14 mainly comprises a pipe 44- a hydrogen gas cylinder 46 which contains hydroliquid container 20 which contains a liquid material gen gas as a carrier gas. Across the gas pipe 44, an (DMAH) 18 from which a process gas for film forming is open-close valve V14. a mass-flow controller 46 and an created, the aforementioned supply pipe line 22 connecting 40 open-close valve VIS are provided in this order between the the liquid container 20 to the process device 16. force feed upstream side and the downstream side. Thus, hydrogen gas means 24 for force-feeding the liquid material 18 toward the supplied to the vaporizing means 26 serves as both a supply pipe line 22, and vaporizing means 26 provided vaporizing gas and a carrier gas.

across the supply pipe line 22 for vaporizing the force-fed A chamber pressure adjustment pipe 48 is diverted from

liquid material 18 to create the process gas. 45 an upstream-side portion of the gas pipe 44, and connected

The liquid container 20 is a sealed container made of e.g. to that portion of (lie supply pipe line 22 which is located

stainless steel and having a capacity of about 81. The inner close to the process device 16. Across the chamber pressure

wall surface of the liquid container 20 is beforehand elec- adjustment pipe 48, an open-close valve V17. a mass-flow

trolytically polished so as to prevent adhesion of gases or controller 50 and an open-close valve V18 are provided in

moisture thereto. An end portion of a gas introduction pipe 50 this order between the upstream side and the downstream

28 across which an manual open-close valve V2 is provided side. Thus, the pressure in the process device 16 can be

is inlroduced into the liquid container 20 above the surface adjusted before the process gas is supplied thereto, thereby

of the liquid material 18. realizing the supply of the process gas with its flow accu

The force-feed means 24 consists of a chemical cylinder rately controlled. 38 filled with Ar gas having a high pressure of e.g. 1 to 3 55 A trap pipe 52 connected to a vacuum pump (not shown), kgf/cm2. and a force-feed pipe 30 connected to the cylinder. etc. for discharging DMAH using a negative pressure has a The force-feed pipe 30 is also connected to the other end of downstream end portion across which an open-close valve the gas introduction pipe 28 via a joint 32. Thus, highly- V9 and a trap unit 54 are provided in this order. Further, the pressurized Ar gas can be supplied from the chemical trap pipe 52 includes first through third pipe portions 52A, cylinder 38 to the container 20 via the force-feed pipe 30. 60 52B and 52C diverted from an upstream end portion thereof. Switching valves VI and V10 are provided in this order The first pipe portion 52A is connected to that portion of the across the force-feed pipe 30 so that the liquid material 18 supply pipe line 22 which is located upstream of the opencan be supplied under 1 to 3 kgf/cm2. A manometer 40 close valve V4, and an open-close valve V8 is provided consisting of e.g. a capacitance manometer is connected, by across the pipe portion 52A. The second pipe portion 52B is means of a communication pipe with an open-close valve 65 connected to that portion of the supply pipe line 22 which is V19. to that portion of the force-feed pipe 30 which is located downstream of the open-close valve V5, and an located between the open-close valves VI and V10. open-close valve V13 is provided across the pipe portion 5 6

52B. The third pipe portion 52C is connected to the vapor- through the carrier gas introduction port 80, and a annular

izing means 26, and an open-close valve V16 is provided groove 130 formed at an end portion of (his passage,

across the pipe portion 52C. Each vaporizing disk 120 employed in the vaporizing

That portion of the force-feed pipe 30 which is located section 140 has a single liquid material passing hole 120c

downstream of the open-close valve VI is connected, by 5 formed in a center portion thereof, and a plurality of carrier

means of a communication pipe 58, to that portion of the gas passing holes 120& formed around the passing hole

supply pipe line 22 which is located downstream of the 120a. The vaporizing disks 120 are arranged adjacent to

open-close valve Vll. An open-close valve V7 and a restric- each other such that the liquid material passing hole 120a

tion valve 56 are provided across the communication pipe corresponds to the passage 114. and the carrier gas passing

58. io holes 1202> correspond to the annular groove 130. These

To purge DMAH using a solvent at the time of cleaning disks are urged by an anvil 135 which contacts a compres

the pipe system, a solvent tank 64 is connected, via a solvent sion spring 136, such that they are brought into contact with

purge pipe 62. to that portion of the supply pipe line 22 eacn other.

which is located downstream of the open-close valve Vll. In the above-described structure, the liquid material 18

The solvent tank 64 contains a solvent for dissolving 15 introduced into the vaporizing means 26 through the liquid

DMAH, for example, normal hexane. An open-close valve introduction port 78 passes the passage 110, the valve

V20 and a restriction valve 60 capable of adjusting its valve mechanism 111 and the passages 112, 113 and 114, which

opening are arranged across the solvent purge pipe 62. To are formed in the main body of the means 26, and then enters

remove DMAH in the vaporizing means 26 a purging Ar gas clearances between the vaporizing disks 120 through the

source 66 is connected, via a purge pipe 68 with an open- 20 liquid material passing hole 120a. On the other hand, the

close valve V12, to that portion of the supply pipe line 22 carrier gas introduced into the vaporizing means 26 through

which is located downstream of the open-close valve V5. the carrier gas introduction port 80 enters the clearances

The purging pressure of the Ar gas source 66 is set to 6 to between the vaporizing disks 120 through the passage (not

9 kgf/cm2. shown), the annular groove 130 and the carrier gas passing

That portion of the supply pipe line 22 which is located 25 holes 120*-1» the clearances of the between the vaporiizng

between the vaporizing means 26 and the process device 16 disks I2*- a pressure drop occurs because of the carrier gas.

is entirely wound by a gas heater 70 consisting of e.g. a tape whereby the liquid material 18 is vaporized as a result of the

heater, as is indicated by the broken lines in FIG. 1. The Joule-Thomson effect. The vaporized material 18. which

heating temperature of the gas heater 70 is set to a constant serves as the process gas, passes exhaustion passages 115

value falling within a range of 30° to 90° C, e.g. 60° C, at and 116 together with the carrier gas, reaches a downstream

which temperature vaporized DMAH is neither returned to portion of the supply pipe line 22 through the process gas

the liquid state, nor thermally decomposed. To prevent exhaustion port 82. and enters the process device 16.

solidification of DMAH which is to be discharged through The operation of the apparatus constructed as above will

the trap pipe 52, that portion of the trap pipe 52 which is 35 now be described.

located upstream of the trap unit 54 is entirely wound by a First, where the open-close valve V6 of the supply pipe

first heater 72 consisting of e.g. a tape heater, as is indicated line 22 and the open-close valve V18 of the chamber

by the broken lines in FIG; 1. The hearing temperature of the pressure adjustment pipe 48. which are incorporated in the

heater 72 is set to e.g. 45° C. In addition, to preheat a carrier process gas supply apparatus 14, are closed, a semiconduc

gas flowing through the carrier gas pipe 44 so as to accel- ^ tor wafer W to be treated is transferred to the process

erate vaporization of the liquid material 18, a downstream container 90 and mounted onto the mount table 94.

portion of the carrier gas pipe 44 is entire wound by a second Subsequently, the pressure in the process container 90 is

heater 74 consisting of e.g. a tape heater, as is indicated by reduced to a base negative value, and the wafer W is heated

the broken lines in FIG. 1. The heating temperature of the by the resistive heater 92 to a predetermined temperature

heater 74 is set to e.g. 35° C. 45 falling within a process temperature range (for example.

The liquid flow control means 42, the vaporizing means 160° to 300° C), e.g. 200°.

26, the mass-flow controllers 46 and 50 and valves VI to Then, to minimize the range of changes in supply amount

V20 (except for the valves V2 and V3) are controlled by a of the process gas due to changes in pressure in the process

microcomputer 160. A carrier gas of an amount sufficient to container 90, the open-close valves V17 and V18 arranged

vaporize the liquid material 18 is supplied at all times to the 50 across the chamber pressure adjustment pipe 48 are opened

vaporizing means 26. before the process gas is supplied into the process container

FIG. 2 shows the structure of the vaporizing means 26. As 99, thereby supplying the process container 90 with H2 gas is shown in FIG. 2. the means 26 has a liquid introduction from the shower head 98 via the chamber pressure adjustport 78 for introducing the liquid material (DMAH) 18 ment pipe 48. As a result, the pressure in the process supplied through the supply pipe line 22, a carrier gas 55 container 90 is set to a predetermined value, e.g. about 2 introduction port 80 for introducing H2 as the carrier gas Torr. falling within a process pressure range (0.1 to 20 Torr). supplied through the gas pipe 44, and a process gas exhaus- After setting the pressure in the process container 90, the tion port 82. The main body of the vaporizing means 26 open-close valves VI and V10 arranged across the forceincludes a vaporizing section 140 with 101 vaporizing disks feedpipe 30, the open-close valve V2 of the gas introduction 120 arranged adjacent to each other, passages 110,112,113 60 pipe 28, the open-close valve V3 of the liquid introduction and 114 for guiding, to the vaporizing section 140. the liquid pipe 34, and the open-close valves Vll. V4 and V5 arranged material 18 introduced into the vaporizing means 26 through across the supply pipe line 22 are opened. At the same time, the liquid introduction port 78, a valve mechanism 111 the valves V14 and V15 arranged across the carrier gas pipe interposed between the passages 110, 112, 113 and 114 44 are opened. In this state, Ar gas pressurized to 1 to 3 (between the passages 110 and 112 in this embodiment), a 65 kgf/cm2 is guided from the Ar gas cylinder 38 to the liquid passage (not shown) for guiding, to the vaporizing section material container 20 via the force-feed pipe 30. By virtue 140, the carrier gas introduced into the vaporizing means 26 of the pressurized Ar gas, the liquid material 18 contained in