WO2006041267A1

WO2006041267A1 - An apparatus for depositing thin film on a wafer

Info

Publication number: WO2006041267A1
Application number: PCT/KR2005/003440
Authority: WO
Inventors: Hong-Joo Lim; Sang-In Lee; Sahng-Kyu Lee; Tae-Wook Seo; Ho-Seung Chang
Original assignee: IPS Ltd
Current assignee: IPS Ltd
Priority date: 2004-10-14
Filing date: 2005-10-14
Publication date: 2006-04-20
Anticipated expiration: 2007-04-14
Also published as: KR20060033139A; TW200629381A; KR100724283B1; TWI300958B

Abstract

A thin film deposition apparatus is provided, including a reactor (100) and a gas box (200) for supplying a reaction gas to the reactor (100). An inert gas heating unit (300) for heating an inert gas for transferring or purging a raw chemical material is installed on an inert gas line S2 of the reactor (100) and/or the gas box (200).

Description

AN APPARATUS FOR DEPOSITING THIN FILM ON A WAFER

TECHNICAL FIELD The present invention relates to an apparatus for depositing a thin film on a wafe r, and more particularly, to a thin film deposition apparatus capable of pre-heating an in ert gas used to transmit or purge a raw chemical material.

BACKGROUND ART A general apparatus for depositing a thin film on a wafer includes a reactor and a gas box for supplying a raw chemical material to the reactor.

Reactors are roughly divided into two types: one is an isothermal reactor whose i nternal temperature is identical to the temperature of a wafer; and the other is a non-iso thermal reactor whose internal temperature is different from the temperature of a wafer. Typically, batch deposition equipment, for example, furnace type batch LPCVD equip ment, is an isothermal reactor, and single-wafer deposition equipment, for example, sin gle-wafer ALD or CVD equipment, is a non-isothermal reactor.

In cases of isothermal or non-isothermal reactors, a raw chemical material is hea ted to increase a vapor pressure, but an inert gas used to transfer or purge the raw che mical material is not heated. Hence, when the inert gas is injected into the reactor, the temperature of the reactor or the wafer fluctuates between an increase and a decreas e.

FIG. 1 is a non-isothermal reactor 10 for use in a conventional thin-film depositio n apparatus. FIG. 2 illustrates, in graphs, a temperature variation versus the flow of an inert gas into the non-isothermal reactor of FIG. 1.

The non-isothermal reactor 10 is an atomic layer deposition (ALD) reactor. As s hown in FIGS. 1 and 2, when a raw chemical material flows into a chamber 11 of the re actor 10 via a source line S1 and a shower head 14 and when a purge gas flows into th e chamber 11 of the reactor 10 via a source line S2 and the shower head 14, the tempe rature of a wafer W on a susceptor 12 changes.

In other words, most of deposition processes are performed at high temperature s of 300^°C or greater. When the purge gas, having a room temperature, is injected int o the reactor 10, the internal temperature of the reactor 10 and the surface temperature of the wafer W rapidly decrease, and thus the temperatures of the reactor 10 and the wafer W fluctuate with a decrease and an increase (see AT₁ of FIG. 2). Hence, the r aw chemical material is not purged but locally solidified or condensed, resulting in an un desired particle or an uneven thin film. The solidification or condensation becomes ser ious particularly when an organic metal compound having a low vapor pressure is used.

Purging by a purge gas typically requires a long period of time, such as, several seconds to several tens of seconds. The solidification and condensation of the raw ch emical material increase the purging period of time, consequently increasing deposition duration.

The solidification and condensation of a raw chemical material due to a rapid cha nge of the temperatures of a reactor and a wafer do not only occur in CVD reactors but also in isothermal reactors.

DETAILED DESCRIPTION OF THE INVENTION

TECHNICAL PROBLEM

The present invention provides a thin film deposition apparatus which can preve nt solidification or condensation of a raw chemical material by minimizing a rapid chang e of the internal temperature of a reactor caused by an inert gas used to transmit or pur ge the raw chemical material, and also can prevent degradation of deposition efficiency by preventing an increase in the purging period of time.

TECHNICAL SOLUTION According to an aspect of the present invention, there is provided a thin film dep osition apparatus including a reactor and a gas box for supplying a reaction gas to the r eactor. An inert gas heating unit to heat an inert gas for transferring or purging a raw c hemical material is installed on an inert gas line of the reactor and/or the gas box.

The inert gas heating unit includes a heater for heating the inert gas line, a temp erature sensor for measuring the temperature of the inert gas line, and an overheating prevention unit for reducing the amount of heat emitted by the heater when the tempera ture sensor generates an overheating signal. Here, the inert gas line has a maze shap e or includes pins to increase the surface area of the interior of the inert gas line.

The inert gas heating unit includes a first inert gas heating unit for heating a purg e inert gas and a second inert gas heating unit for heating an inert gas for transferring t he raw chemical material. The first inert gas heating unit emits such an amount of hea t that the temperature for heating the purging inert gas is equal to or greater than the te mperature for heating the insert gas for transferring the raw chemical material.

The inert gas heating unit emits such an amount of heat as to heat an inert gas fl owing via the inert gas line to 40 to 350^°C.

The reactor includes: a chamber in which a susceptor for seating a wafer thereo n is installed; and a shower head installed in the upper part of the interior of the chamb er to spray gas to the susceptor. The inert gas heating unit is installed over the chamb er to heat an inert gas flowing through an inert gas line connected to the shower head.

The reactor includes: a chamber in which a wafer support for seating a plurality o f wafers thereon is installed; and an injector spraying gas onto the wafers. The inert g as heating unit is installed on a predetermined portion of the chamber to heat an inert g as flowing through an inert gas line connected to the injector.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a non-isothermal reactor for use in a conventional thin-film deposition a pparatus.

FIG. 2 illustrates, in graphs, a temperature variation versus the flow of an inert ga s into the non-isothermal reactor of FIG. 1.

FIG. 3 is a schematic diagram of a thin film deposition apparatus employing an in ert gas heating unit, according to an embodiment of the present invention. FIG. 4 illustrates an embodiment of the inert gas heating unit shown in FIG. 3.

FIGS. 5A and 5B are a front view and a side cross-sectional view, respectively, o f another embodiment of the inert gas heating unit shown in FIG. 3.

FIGS. 6 through 8 illustrate inert gas lines in which pins are formed to increase ar eas of the insert gas lines that contact an inert gas. FIG. 9 illustrates a non-isothermal reactor employing an inert gas heating unit, w hich is for use in the thin film deposition apparatus of FIG. 3.

FIG. 10 illustrates, in graphs, a temperature variation versus the flow of an inert g as into the non-isothermal reactor of FIG. 9.

FIG. 11 illustrates an isothermal reactor employing an inert gas heating unit, whic h is for use in the thin film deposition apparatus of FIG. 3.

FIG. 12 illustrates an example of a gas box employing an inert gas heating unit, which is for use in the thin film deposition apparatus of FIG. 3.

FIG. 13 shows, in a graph, data in which the number of generated particles incre ase with an increase in the number of deposition wafers when no inert gas heating units are employed.

FIG. 14 shows, in a graph, data in which the number of generated particles does not change much even with an increase in the number of deposition wafers when an in ert gas heating unit is employed. BEST MODE

A thin film deposition apparatus according to the present invention will now be de scribed in detail with reference to the accompanying drawings, in which embodiments of the invention are shown. FIG. 3 is a schematic diagram of a thin film deposition apparatus employing an in ert gas heating unit 300, according to an embodiment of the present invention. As sho wn in FIG. 3, the thin film deposition apparatus is roughly divided into a reactor 100 and a gas box 200 for supplying a reaction gas to the reactor 100. The reactor 100 and th e gas box 200 are connected to each other by a plurality of source lines S1 for transferri ng a raw chemical material and an inert gas line S2 for delivering an inert gas for purgin g the raw chemical material. According to the present invention, the inert gas heating unit 300 is installed on the inert gas line S2 of the reactor 100 and/or the gas box 200 in order to heat the inert gas for transferring or purging the raw chemical material. In th e present embodiment, inert gas heating units 300 are installed in the reactor 100 and t he gas box 200. The inert gas heating unit 300, which heats the inert gas flowing withi n the inert gas line S2, may be implemented in various forms.

FIG. 4 illustrates an embodiment of the inert gas heating unit 300. FIGS. 5A an d 5B are a front view and a side cross-sectional view, respectively, of another embodim ent of the inert gas heating unit 300. As shown in FIG. 4, the inert gas heating unit 300 may be implemented into a str ucture in which the inert gas line S2 is wound around a heater 310.

As shown in FIGS. 5A and 5B, the inert gas heating unit 300 may be implemente d into an inert gas heating unit 300^' in which an inert gas path is formed in the shape of a maze M. In other words, the inert gas heating unit 300^' has a plate-shaped inert ga s line S2^' in which the maze M is formed. When a heater 310^' is installed within the p late-shaped inert gas line S2^' as shown in FIG. 5B, the inert gas can be effectively heat ed.

The inert gas heating unit 300 (300 ) is organically connected to a temperature s ensor (not shown) for measuring the temperature of the inert gas line S2 (S2 ) and a ov erheating prevention unit (not shown) for decreasing the amount of heat emitted by the heater 310 (310 ) when the temperature sensor generates an overheating signal. Con sequently, the inert gas line S2 (S2 ) can be kept at a suitable temperature. Since the temperature sensor and the overheating prevention unit are well known, a detailed desc ription thereof will be omitted. FIGS. 6 through 8 illustrate inert gas lines S2 including pins to increase areas of t he insert gas lines that contact an inert gas. As shown in FIG. 6, the interior of a cylindrical inert gas line S2 may be formed s o that pins P1 protrude horizontally first from one side then from the other. As shown i n FIG. 7, the interior of the cylindrical inert gas line S2 may be formed so that pins P2 st retch in all direction from the center of the inert gas line S2 to the inner circumference t hereof. As shown in FIG. 8, the interior of an inert gas line S2, which is a rectangular block, may be formed so that pins P3 protrude horizontally first from one side then from the other. The pins P1 , P2, and P3 increases an area of the inert gas line S2 that co ntacts the inert gas flowing therein, leading to more effective heating of the inert gas.

The inert gas heating unit 300 may be comprised of a first inert gas heating unit f or heating a purge inert gas and a second inert gas heating unit for heating an inert gas for transferring a raw chemical material. In this case, the first inert gas heating unit s hould emit such an amount of heat that the temperature for heating the purging inert ga s can be equal to or greater than the temperature for heating the insert gas for transferri ng the raw chemical material. The inert gas heating unit 300 should emit such an amount of heat as to heat an inert gas flowing via the inert gas line S2 to 40 to 350^"C.

The reactor 100 may be an isothermal reactor whose internal temperature is the same as the temperature of a wafer or a non- isothermal reactor whose internal temper ature is different from the temperature of a wafer. FIG. 9 illustrates a non-isothermal reactor employing the inert gas heating unit 30

0, which is for use in the thin film deposition apparatus of FIG. 3. FIG. 10 illustrates, in graphs, a temperature variation versus the flow of an inert gas into the non-isothermal reactor of FIG. 9.

When the reactor 100 is a non-isothermal reactor using a ALD or CVD method a s shown in FIG. 9, the non-isothermal reactor include a chamber 110 including a susce ptor 120 on which a wafer W is seated, and a shower head 130 installed in the upper p art of the interior of the chamber 110 to spray gas to the susceptor 120. The inert gas heating unit 300 is installed over the chamber 110 to heat an inert gas line S2 connecte d to the shower head 130. When the ALD method is used, deposition occurs at a high temperature, for exa mple, at 300^°C or greater. A purge gas having a room temperature is heated to a pred etermined temperature by the inert gas heating unit 300 before being introduced into th e reactor 100, and thus a difference between the temperature of the heated purge gas i ntroduced into the reactor 100 and the temperature of the wafer W is small compared w ith a conventional art not using a heating unit (see FIG. 10). Hence, local solidification or condensation of the raw chemical material can be minimized, leading to smooth purg ing. Also, generation of unwanted particles decreases, and a uniform reaction can be i nduced, leading to formation of a uniform thin film. These effects become larger when an organic metal compound having a low vapor pressure is used as the raw chemical material.

FIG. 11 illustrates an isothermal reactor employing the inert gas heating unit 300, which is for use in the thin film deposition apparatus of FIG. 3. When the reactor 100 is an isothermal reactor as shown in FIG. 11, the isothermal reactor 100 includes a cha mber 150 including a wafer support 160 on which a plurality of wafers W are seated, an d an injector 170 for spraying gas onto the wafers W. The inert gas heating unit 300 is installed on a predetermined portion of the chamber 150 to heat an inert gas line S2 c onnected to the injector 170.

FIG. 12 illustrates an example of the gas box 200 of FIG. 3 employing the inert g as heating unit 300. As shown FIG. 3, the gas box includes a canister 210 for accom modating the raw chemical material, a plurality of gas lines (source lines) connected to t he canister 210, and a plurality of valves. These components are installed within a bo x 220. The inert gas heating unit 300 is installed on the box 220. An inert gas is heat ed by the heating unit 300 and then transferred to the canister 210 or introduced into th e reactor 100 via the source line S2. The inert gas is N₂ or Ar. In the present embodi ment, the heating unit 300 heats a heating line 320 to 120^°C or more so that the inert g as flowing within the heating line 320 can have a temperature of 60^°C or greater. The i nert gas is re-heated to 80 to 15O⁰C within the gas box 200. It is preferable that the te mperature of the inert gas for use as a purge gas is identical to the deposition temperat ure. However, in single-wafer deposition equipment, it is effective that the temperature of the inert gas for use as a purge gas is about 150^°C.

FIG. 13 shows, in a graph, data in which the number of generated particles incre ase with an increase in the number of deposition wafers when no inert gas heating units are employed. FIG. 14 shows, in a graph, data in which the number of generated par tides does not change much even with an increase in the number of deposition wafers when an inert gas heating unit is employed.

In FIGS. 13 and 14, ■ indicates the number of particles. The number of partic Ies is greatly smaller when an inert gas heating unit is employed (see FIG. 14) than whe n no inert gas heating units are employed (see FIG. 13).

As described above, in a thin film deposition apparatus according to the present i nvention, the inert gas heating unit 300 is installed in the reactor 100 and/or the gas box 200 to heat an inert gas, such as, N₂ or Ar, to a high temperature. Thus, more efficie nt deposition can be achieved.

In particular, when the inert gas is used as a carrier gas, a raw chemical material having a low vapor pressure can have a sufficient vapor pressure, and thus the genera tion of particles is minimized and incident effects, such as, an improvement of purging e fficiency, are generated. In addition, the local solidification or condensation is prevent ed, leading to a remarkable reduction of the number of generated particles.

Due to the use of an inert gas heating unit, a thin film having an excellent step co verage can be obtained. Due to the heating of a carrier gas (inert gas) to a high tempe rature, the absorption of a raw chemical material can improve, and solidification is prev ented. Thus, efficient purging is achieved, and the conformality can improve.

In particular, in an ALD method, a purging operation used to leave only a chemis orbed molecule layer absorbed to the surface of a wafer and remove a physisorbed mol ecule layer after a raw chemical material is injected into the reactor 100 is the longest a mong other operations. Thus, the period of time required to deposit an atomic layer ca n be reduced by decreasing the purging period of time. This lead to a reduction of a u nit deposition period of time, resulting in an improvement of the productivity.

A heating unit according to the present invention improves the characteristics an d productivity of a thin film when an ALD method is used. Also, the heating unit is appl ied to all processes using the same concept as that of an ALD method, thus forming an excellent thin film.

As described above, a thin film deposition apparatus according to the present inv ention can minimize a rapid change of the internal temperature of a reactor caused by a n inert gas by pre-heating the inert gas (purge gas and carrier gas) introduced into the r eactor and/or a gas box. Thus, solidification or condensation of a raw chemical material can be prevented, and generation of unwanted particles can also be prevented. Furthe rmore, deposition efficiency can be improved by preventing an increase in the purging p eriod of time. While the present invention has been particularly shown and described with refer ence to exemplary embodiments thereof, it will be understood by those of ordinary skill i n the art that various changes in form and details may be made therein without departin g from the spirit and scope of the present invention as defined by the following claims.

Claims

1. A thin film deposition apparatus comprising: a reactor; and a gas box supplying a reaction gas to the reactor, wherein an inert gas heating unit to heat an inert gas for transferring or purging a raw chemical material is installed on an inert gas line of the reactor and/or the gas box

2. The thin film deposition apparatus of claim 1 , wherein the inert gas heating unit c

' omprises: a heater heating the inert gas line; a temperature sensor measuring the temperature of the inert gas line; and an overheating prevention unit reducing the amount of heat emitted by the heate r when the temperature sensor generates an overheating signal.

3.

The thin film deposition apparatus of claim 2, wherein the inert gas line has a ma ze shape to increase the surface area of the interior of the inert gas line.

4.

The thin film deposition apparatus of claim 2, wherein the inert gas line has pins t o increase the surface area of the interior of the inert gas line.

5.

The thin film deposition apparatus of claim 1 , wherein the inert gas heating unit c omprises: a first inert gas heating unit heating a purge inert gas; and a second inert gas heating unit heating an inert gas for transferring the raw chem ical material, wherein the first inert gas heating unit emits such an amount of heat that the tern perature for heating the purging inert gas is equal to or greater than the temperature for heating the insert gas for transferring the raw chemical material.

6.

The thin film deposition apparatus of claim 1 , wherein the inert gas heating unit e mits such an amount of heat as to heat an inert gas flowing via the inert gas line to 40 t o 35O⁰C.

7. The thin film deposition apparatus of claim 1 , wherein: the reactor comprises: a chamber in which a susceptor for seating a wafer there on is installed; and a shower head installed in the upper part of the interior of the cham ber to spray gas to the susceptor; and the inert gas heating unit is installed over the chamber to heat an inert gas flowin g through an inert gas line connected to the shower head.

8. The thin film deposition apparatus of claim 1 , wherein: the reactor comprises: a chamber in which a wafer support for seating a plurality of wafers thereon is installed; and an injector spraying gas onto the wafers; and the inert gas heating unit is installed on a predetermined portion of the chamber t o heat an inert gas flowing through an inert gas line connected to the injector.