TWI228153B - Method of forming a thin film using atomic layer deposition method - Google Patents

Abstract

The present invention discloses a method of fabricating a thin film using an atomic layer deposition, the method including: a first step of disposing a silicon substrate in a reaction chamber; a second step of introducing a first reactive gas and a carrier gas into the reaction chamber during a first period such that the first reactive gas is chemically adsorbed on the silicon substrate, wherein the reaction chamber is set to a first pressure during the first period; a third step of introducing a second reactive gas into the reaction chamber during a second period such that the second reactive gas is chemically adsorbed on the silicon substrate and discharges a residual portion of the first reactive gas out of the reaction chamber, wherein the reaction chamber is set to a lower second pressure than the first pressure during the second period; and further introducing the second reactive gas into the reaction chamber for a third period such that the second reactive gas is further chemically adsorbed on the silicon substrate, wherein the reaction chamber is set to a higher third pressure than the first pressure during the third period.

Description

1228153 V. Description of the invention (1) Crossed rabbit soil information This patent application is based on Korean Patent Application No. 2 0 0-3 1 0 4 0, filed on June 7, 2000. The Korean The patent applications are hereby incorporated by reference. FIELD OF THE INVENTION The present invention relates to a method for forming a thin film by using an atomic layer deposition method (ALD, Atomic Layer D e ρ 〇 siti ο η), and particularly to a method for forming a thin film by using an atomic layer deposition method that shortens a process cycle. method. Description of Related Technology Generally speaking, thin films can be widely used in, for example, dielectric layers of semiconductor devices, light-transmissive conductive elements of liquid crystal display devices, and passivation layers of light-emitting devices. Many well-known techniques of this type apply thin films to the substrate I. Among the more fully developed thin-film applications, evaporation, chemical vapor deposition, and ALD are often used. CVD has better productivity than ALD. However, in the CVD method, the use of a gas source including chlorine gas to make a thin film will cause impurities such as chlorine atoms to remain in the thin film. Therefore additional procedures such as plasma processing will be required to remove impurities from the film. Recently, the CVD method is often operated at a low pressure to achieve the desired step coverage and uniform film thickness, and also to avoid pollution caused by operation at normal pressure. However, the low coating rate caused by the low pressure has caused the CVD method to lose much of its efficiency. To increase the south forging film rate ’will require

1228153 V. Description of the invention (2) Reaction temperature. However, when the partial pressure of a reactive gas is increased, the reactive gas reacts with other non-reactive gases, and contaminated particles are formed as a by-product. In addition, the 5 high reaction temperature also caused the distortion of the remaining film layer under the coating during the manufacturing process (distortion). Compared with the CVD method, the ALD method has lower production efficiency. However, by the method, the thin film can be formed at a lower temperature and has a better step coverage and a more uniform composition. In addition, films made by the ALD method have a lower impurity content. / FIG. 1 illustrates a method for forming a thin film using a conventional A LD technology according to U.S. Patent No. 4,41 3,022. In the first period (ctl), the first reaction gas is passed into the reaction chamber and the gas is stored in the reaction chamber at the first stage pressure (CP1). At this time, the silicon substrate to be formed into a thin film is already installed in the reaction chamber. Then in the second stage (ct2), the inflow of the first reaction gas is stopped and an inert gas is passed into the reaction chamber, usually argon (Ar) or helium (He). The inert gas will prevent the Shi Xi substrate from over-adsorbing the first reaction gas, and the remaining unreacted gas will be discharged from the reaction chamber. Then, at the third time: (ct3) A second reaction gas, that is, a reducing gas, is introduced into the reaction chamber and the gas is stored in the reaction chamber at a second stage pressure (CP 2). Then, the inflow of the second reaction gas is stopped and an inert gas is introduced into the reaction chamber during the fourth period (c 14), which is usually still Ar or He. This inert gas will cause residual unreacted gas to exit the reaction chamber. Here, the low pressure values of CP1 and CP2 minimize the time during which the silicon substrate is exposed to the first and second reactive gases. In addition, the reaction chamber is inert

1228153 V. Description of the invention (3) The time of the gas must be sufficient to exhaust the remaining non-reactive parts of the first and second reaction gases. In order to illustrate the application of the above-mentioned ALD method, reference is made to FIG. 1 to explain a procedure for forming an aluminum oxide (A1 2 03) film by the conventional ALD method. At a coating temperature of about 37 ° C and a pressure of about 230 mTorr (CP1), trimethyl (Aluminum) (TMA) was introduced into the reaction chamber for about 1 second, which is a ctl period. Then, the inflow of TMA is stopped and Ar is introduced into the reaction chamber for about 14 seconds, which is a period of c 12. A r will prevent the TMA from being excessively adsorbed on the silicon substrate and allow the remaining unreacted gas to exit the reaction chamber. After that, distilled water (DIW, di st i 1 led water) vapor was passed into the reaction chamber for about 1 second at a pressure of about 200 mTorr (CP2), which is a period of ct3. Then, the inflow of TMA is stopped and Ar is again introduced into the reaction chamber for about 14 seconds. This is the ct4 period. Ar will cause the remaining unreacted gas to exit the reaction chamber. After the above procedure of about 30 seconds, an aluminum oxide film with a thickness of only 0.3 nm will be manufactured. Therefore, in order to produce a 100 nm aluminum oxide film, the above cycle must be repeated about 34 times. In other words, it takes about 100 seconds to manufacture a 10 nm-thin film by the UD method. As mentioned above, the processing time required for conventional ALD will be much longer than CVD. For example, a large number of cluster equipment will be needed to make up for the longer process time, and the cost of manufacturing thin film by using Aι ^ will increase accordingly. ^ Summary of the Invention The present invention relates to a method for forming a thin film using ALD technology.

Page 8 1228153 V. Description of the invention The method will be eliminated. This technology can be understood by making the technology. To achieve the ALD, a thin silicon substrate is used to form a reaction gas, and the reaction is passed into the top and the residue is kept in a relatively short period before being passed on the silicon substrate. Carry a second reagent gas. Such gases can be (4) one or more of the problems caused by the limitations and omissions of the technology itself.

One of the objectives of the invention is to provide an ALD film with a shortened process time. Other features and advantages of the invention will be more clearly understood from the following description or embodiments. To achieve the above object, a preferred embodiment of the present invention provides a method using an I film. The method includes the following steps: first, installing in a reaction chamber; second, introducing a first body and a carrier gas during a first period of time, the reaction gas chemically adsorbs in a silicon substrate chamber and maintains a first pressure Under pressure; third, in the second period, two kinds of reaction gases which discharge the first reaction gas chemically adsorbed on the silicon substrate and left in the reaction chamber, and under the second pressure of the first pressure in the reaction chamber; Fourth, a reaction gas is introduced at the third hour, and the reaction gas is further chemisorbed. The reaction chamber is maintained at a third pressure higher than the first pressure. The pressure gas is passed into the reaction chamber during the second and third periods. The fourth to fourth steps should be repeated at least twice. In an embodiment, the first reaction gas includes titanium atoms, and the second body includes nitrogen atoms, and a titanium nitride film will be formed on the Shixi substrate. The first reaction gas may be titanium tetrachloride, and the second reaction gas Ammonia. At this time, the temperature of the reaction chamber is 500 degrees, and the first period is 1228153. I. The first pressure of the invention description (5) is 0.04 to 0 · 〇6 τ〇ΓΓ, and the second time is $ 0 0 0 8 to 0. 012 Torr, the first: hour #, and the first pressure is T〇rr. The first period is usually Q.8 to the third period is 8 to 12 seconds. Right horse for 3 to 5 seconds, the two reaction gases contain oxygen source +, then the oxidized Ming thin flag will be on. In this way, the first reaction gas may be TMA, and may be MW. At this time, the temperature of the reaction chamber is _, the pressure of the first reaction chaos is 0.2 to 0.3 Torr, and the second period of the first period is π Πβ τ. To 〇06 Τ〇ΓΓ, the third pressure in the third period is 〇2 to 0.3. The period is usually 0.8 to U seconds, the period: 3.2 to 4.8 seconds, and the period ί is 4 to 6. second. Brother Yi calls f understand that this summary and the subsequent detailed description are only for demonstration and overview, and the scope of patent application will provide a more detailed explanation of the present invention. Detailed description of blankets _ actual _ examples The preferred embodiments of the present invention will be described in detail below with reference to the drawings. First preferred embodiment

According to the first preferred embodiment, a method for forming a titanium nitride (TiN) film by using ALD will be described with reference to FIGS. 2 and 3. As shown in FIG. 3, in a first step 10, a silicon substrate having an oxide layer is installed in a reaction chamber. The temperature of the reaction chamber was adjusted to 500 degrees. Next, in a second step 20, a first reaction gas and a carrier gas are passed into the reaction chamber, usually titanium tetrachloride (Ticl 4) and Ar. Figure 2

Page 10 1228153 V. Description of the invention (6), at this time it is 11 periods, the pressure (P1) of the reaction chamber is set between 0.04 to 0.06 Torr, and titanium tetrachloride and Ar The flow rate ranges from 80 to 120 seem (1 seem is the volume of 1 standard cubic centimeter of gas per minute, and the volume of 1 standard cubic centimeter of gas is measured at 25 degrees and 1 atmosphere). The 11 period is usually 0.8 to 1.2 seconds. Under the above conditions, titanium tetrachloride chemically adsorbs on the Shixi substrate during the rhenium period. In order to reduce unnecessary physical adsorption (P h y s i c a 1 adsorption), the above-mentioned chemical adsorption of the first reaction gas must be performed at the minimum pressure and the shortest time. Ar, which is a carrier gas, is an inert gas, which can reduce the probability of a reaction between the residual gas in the reaction chamber and the second reaction gas that is subsequently passed into the reaction chamber. In addition, if the first reaction gas has a slight viscosity, the carrier gas can be used to dilute and reduce its viscosity to prevent the gas from adsorbing on the reaction chamber. After the period t1, in the third step 30a and 3 Ob, the second reaction gas is passed into the reaction chamber, usually ammonia (NH 3). At this time, the flow rate of the ammonia gas ranges from 24 0 to 360 seem. The pressure in the reaction chamber (P2) is set between 10 · 0 0 8 and 0 · 0 12 T rr, which is lower than the pressure (P1) of titanium tetrachloride and Ar. Under the above conditions, the nitrogen element in the ammonia gas is chemically adsorbed on the silicon substrate and forms a T i N film in the second period, that is, the 12 period. The t2 period is usually 3 to 5 seconds. At this time, the second reaction gas is also used to discharge the titanium tetrachloride gas remaining in the reaction chamber but not chemically adsorbed on the silicon substrate out of the reaction chamber. Subsequently, in a fourth step 40, a second reaction gas, namely ammonia gas, is passed into the reaction chamber. At this time, the flow rate of the ammonia gas is in the range of 2 40 to 3 6 0.

1228153 V. Description of the invention (7) ~ ^ seem 'and the pressure (p3) of the reaction chamber is set between 0.2 and 0.3 T 〇' r 'This pressure is higher than the pressure of titanium tetrachloride and Ar ( P1). Under the above conditions, the nitrogen element in the ammonia gas is more closely adsorbed on the silicon substrate in the third period, that is, the t3 period, and continues to form a TN film. This = segment is usually 8 to 12 seconds. The office will use a shower he ad that is widely used in TCVD ’thermal chemical vapor deposition to inject the various gases mentioned above. This method at the beginning of the process = produces only a small amount of impurities. However, the content of impurities will increase after the nozzle is repeatedly exposed to each reaction gas. That is, when the nozzle repeatedly contacts each reaction gas, its incomplete reaction will cause an increase in the content of impurities. In order to avoid the problem of the conventional ejector described above, a better choice is to use a multiple ejector with a plurality of or holes to inject titanium tetrachloride, ammonia, and Ar. According to the first preferred embodiment, it is completed. The cycle of the above procedure takes 1 1 · 8 to 18 · 2 seconds. In one process cycle, a titanium nitride film with a thickness of 12 to 1.8 nanometers can be obtained. This titanium nitride film can be filled at the bottom diameter of 0.3

Micron and depth-to-diameter rat i 〇 contact holes of 3.8 still have a step coverage of more than 90%. In addition, the resistivity of the titanium nitride film is about 130 v Q cm. At this time ', if a chlorine atom is contained in the thin film, the chlorine atom will react with water gas in the gas and form strong acid gasified hydrogen. The hydrogenated gas not only damages the thin film, but also damages the metal circuit 'formed on the thin film, causing the reliability of the metal circuit to decrease. However, using the nitrogen formed by the first preferred embodiment

Page 121228153 V. Description of the invention (8) The density of chlorine atoms in the titanium oxide film is lower than the limit of energy measured by X-ray photoelectron spectroscopy (XPS). That is, according to the first preferred implementation The example method can improve the reliability of metal circuits on thin films and can be applied to smaller metal circuits. Second Preferred Embodiment According to a second preferred embodiment, a method for forming an aluminum oxide (A 1 20 3) film using ALD will be described with reference to FIGS. 2 and 3.

In a first step 10, a silicon substrate having an oxide layer is set in a reaction chamber. The temperature of the reaction chamber was adjusted to 50 ° C. Then in a second step 20, the first reaction gas and the carrier gas are passed into the reaction chamber, usually TMA and Ar. This is the tl period, and the pressure (pi) of the reaction chamber is set between 0.2 and 0.3 Torr, and the flow rate range of TMA and Ar is 80 to 120 seem. The tl period is usually 0.8 to 1.2 seconds. Under the above conditions, TMA was chemically adsorbed on the silicon substrate within 11 hours. Next, in the third step 30th stage 30b, the second reaction gas is passed into the reaction chamber, usually DIW, with a flow rate ranging from 80 to 120 seem, and the pressure (P2) of the reaction chamber is set at 0 · Between 〇4 and 〇6 Torr, this pressure is lower than the pressure (pi) of TMA and Ar. Under the above conditions, the oxygen elements in the]] boundary are chemically adsorbed on the silicon substrate and form a thin oxide film in the second period, that is, the 12th period. The t2 period is usually 3.2 to 4.8 seconds. At this time, the inert gas Ar is also used to discharge the TMA gas remaining in the reaction chamber but not chemically adsorbed on the silicon substrate ^ out of the reaction chamber. That is, Ar molecules collide with the residual TMA gas which is physically adsorbed on the oxide film, and is effectively exhausted.

Subsequently, in a fourth step 40, the second reaction gas is DIW

Page 13 1228153 V. Description of the invention (9) and the inert gas Ar is passed into the reaction chamber. At this time, the flow rate ranges from 80 to 120 sccm 'and the pressure of the reaction chamber (P3) is set to 0.2 to 0.2. 3 Torr 'This pressure is the pressure between TM and A r (P1). Under the above conditions, the oxygen element in the DIW is chemically more closely adsorbed on the silicon substrate in the third period t 3 and continues to form an aluminum oxide film. This t3 period is usually 4 to 6 seconds. At this time, the 'inert gas Ar is used to prevent or reduce physical adsorption of D I W. As with the first preferred embodiment, the preferred choice here is to use a multi-injector with a plurality of sharp holes to inject gases such as TMA, Ar, and DIW. According to the first preferred embodiment, the cycle for completing the above procedure takes time 8

To 12 seconds. In one process cycle, an oxide film having a thickness of 0.17 to 0.25 nm can be obtained. This alumina film can still have a step coverage of more than 90% when filling holes with a bottom diameter of 0.3 microns and an aspect ratio of 3.8. In addition, the alumina film has a reflective index of i 6 and 1 β 62 with respect to a silicon substrate and a silicon oxide (si 1 icon oxide) film under a light wavelength of 6 3 3 nm. The alumina film formed using the second preferred embodiment also contains a carbon atom density lower than the XPS * energy measurement limit. That is, the oxide film made according to the method of the second preferred embodiment has better density and electrical properties (e 1 e c t r i C quality).

As mentioned earlier, after a process of about 12 seconds, a thin oxide film with a thickness of 0.17 nm will be manufactured. Therefore, in order to manufacture a 10-n-thick alumina film, the above cycle must be repeated about 60 times. In other words, it takes about 7200 seconds to make a 100 nm aluminum oxide film using the first preferred embodiment. The conventional ALD technology takes about 1000 seconds to make a 1 () η 嶙 alumina.

1228153 V. Description of the Invention Compared with the film, the present invention provides better productivity. Those skilled in the art should understand that the method for manufacturing a thin film transistor described in the present invention may be changed or modified without departing from the spirit of the present invention. Therefore, the scope of the present invention shall include the scope of the attached patent application and all modifications and changes equivalent to the scope of the patent application.

Page 15 1228153 Brief Description of Drawings Figure 1 is an explanatory diagram of forming a thin film by the conventional ALD technology. FIG. 2 is an explanatory diagram of forming a thin film by using an ALD technique according to a preferred embodiment of the present invention. FIG. 3 is a flowchart of forming a thin film by using the ALD technology according to a preferred embodiment of the present invention. Symbol Description

10 Set the silicon substrate in the reaction chamber 20 First chemisorption 3 0 a Second chemisorption 30b Remove unreacted gas 40 Third chemisorption

Claims (1)

丨 / Teng 1, — "Case No. 90 ^ 4023 VI. Application for Patent Scope 1 A method for manufacturing a thin film by atomic layer deposition (ALD), including the following steps: · The first step is to mount a stone substrate It is set in a reaction chamber. In the second step, the first reaction gas and a carrier gas are passed into the reaction chamber in the first period, and the reaction gas is chemically adsorbed on the silicon. On the substrate, the pressure of the reaction chamber is maintained at the first pressure in the second period; the second chamber passes the second reaction gas into the anti-i 化学 chemically adsorbed in Shi Xi in the second period. On the substrate, the ten reaction gases remaining in the reverse period are discharged to maintain the pressure in the reaction chamber. The pressure in the reaction chamber is lower than the first pressure in the second and fourth steps. The second pressure is the same as the pressure in the reaction chamber. During the time period, the second reaction gas is passed into the chamber, and the second gas is further chemically adsorbed on the silicon substrate, and the reaction force is. —Pan Duan maintains a pressure higher than the second pressure, the third calendar, and the second one. In the first area, the application room for manufacturing thin molds by atomic layer deposition is used. In the third period, the carrier gas needs to be further passed into the reverse method, among which: " ^ surrounding item 1 by using the atomic layer deposition method to manufacture the chamber. In the second period, the carrier gas film needs to be further connected. 1228153 on page 17 "Revised year and month case number 90111423. VI. Patent Application Scope 4. If the patent application scope item 1 uses the atomic layer deposition method to make a thin film, the second to fourth steps need to be repeated in order At least twice. 5. The method for manufacturing a thin film by atomic layer deposition according to item 1 of the scope of patent application, wherein: the first reaction gas contains titanium (T i), and the second reaction gas contains nitrogen (N) A titanium nitride (T i N) thin film is formed on a silicon substrate. 6. For example, the method for manufacturing a thin film by atomic layer deposition method in the scope of patent application No. 5 in which the first reaction gas is titanium tetrachloride ( TiCl4), the second type of reaction gas is ammonia (NH3). 7. For example, the method of manufacturing thin film by atomic layer deposition method in the scope of patent application item 6, wherein the temperature of the reaction chamber is set to 500 degrees, the first period The first pressure is 0.04 to 0.06 Torr, the second pressure is 0.008 to 0.01 2 T or r, and the third pressure is 0.2 to 0.3 Torr 〇8. Use of scope item 7 Sublayer deposition method for manufacturing a thin film, wherein: the first period is 0.8 to 1.2 seconds, the second period is 3 to 5 seconds, and the third period is 8 to 12 seconds. A method for manufacturing a thin film by an atomic layer deposition method according to item 1, wherein: the first reaction gas contains aluminum (A1); Page 18 1228153 Case No. 90114023 January 6, Patent Application Scope The gas should contain oxygen (0), and alumina (A 12 03) film is formed on a silicon substrate. 10. For example, the method for manufacturing a thin film by atomic layer deposition according to item 9 of the scope of patent application, wherein: the first reaction gas is trimethylaluminum (TMA), and the second reaction gas is distilled water vapor (DIW). 11. For example, a method for manufacturing a thin film by atomic layer deposition according to the scope of patent application No. 10, wherein: the temperature of the reaction chamber is set to 350 degrees, the first pressure is 0.2 to 0.3 Torr, and the second The second pressure in the period is 0.04 to 0.06 Torr, and the third pressure in the third period is 0.2 to 0.3 Torr 〇12. For example, if the method for manufacturing a thin film by atomic layer deposition method is applied in item 11 of the patent application scope, Among them, the first period is 0.8 to 1.2 seconds, the second period is 3, 2 to 4.8 seconds, and the third period is 4 to 6 seconds. Page 19