The disclosure relates to a method for processing a substrate, and more specifically to a method for minimizing a damage to underlayer of a substrate during processing using plasma in a reactor.
As the line width of a semiconductor circuit shrinks, the demand for low temperature processes to protect the semiconductor device from a thermal budget in conventional thermal processes has been increasing.
The plasma enhanced atomic layer deposition (PEALD) method has often been used for low temperature processes since the PEALD method uses a plasma to activate reactant gas and to facilitate a precise control of film thickness and uniformity on three-dimensional patterned structure at low temperature. For instance, the PEALD method facilitates a SiO2 layer formation as a patterning layer at low temperature by activating an oxygen reactant gas by plasma.
When an oxide layer (e.g. SiO2 layer) is used as a patterning layer deposited by PEALD method on a photo-resist (PR) patterned structure that includes carbon, a photo resist underlayer may be damaged due to a strong reactivity of oxygen radicals. The damage to the underlayer may continue until the SiO2 layer is deposited to a certain thickness. In general, the underlayer damage less than 5 Å may be allowed as it may be within the range that does not significantly affect device performance. However, when the high intensity of RF power is applied to deposit a high wet etch resistant SiO2 layer, the underlayer damage may significantly affect the device performance. Thus, in case of process condition to which high RF power is applied, a substrate processing method in which an underlayer damage is minimized and the damage is within a range that does not significantly affect the device performances may be necessary.
In conventional substrate processing method, a liner film as a protective layer may be formed on the photo resist to solve that issue. The liner layer is formed by adsorbing a source material on the photo resist without providing oxygen radicals. For instance, an aminosilane silicon source may be provided, followed by providing an activated Ar gas. The activated Ar gas dissociates the silicon source gas and the SiCN layer as a liner layer is formed on the photo resist. After that, a Si source and an oxygen plasma are provided alternately and sequentially to form SiO2 layer as a patterning layer on the SiCN layer, and at least a part of the SiCN layer is converted into SiO2 layer by reacting with the oxygen radicals. However, the photo resist underlayer is still damaged by highly active oxygen radicals. To solve that issue, the thickness of SiCN layer may be increased, but it also causes SiCN layer to be intermixed into SiO2 layer and results in non-uniform SiO2 layer properties throughout the SiO2 layer. As a result, as two films with different compositions are stacked, the wet etch property of the film may not be uniform throughout the film. Also, as the semiconductor device shrinks more and the spacing between patterned structure of the semiconductor device becomes narrower, thinner SiO2 patterning layer may be required to be formed on the patterned structure. Therefore when the SiCN layer becomes thick, the whole SiO2 layer gets to include a SiCN layer and a SiO2 layer together that is not fully converted from SiCN layer, thus the wet etch property of a SiO2 layer is not uniform. In addition, the thickness of SiO2 layer may exceed the required thin thickness. On the contrary, when the SiCN layer is thin, the photo resist underlayer may be directly damaged from active oxygen radicals, as shown by a loss of photo resist layer, a partial deformation of photo resist, or etc.
The present disclosure provides a method for minimizing a damage to underlayer of a substrate in substrate processing method using plasma in a reactor.
In one or more embodiment, the substrate processing method may include a first phase of forming a liner layer and a second phase of forming a deposition layer.
In one or more embodiment, the first phase of forming a liner layer is comprised of providing a first reactant and the third reactant to the patterned structure and forming a first source layer on the surface of the patterned structure.
In one or more embodiment, in the first phase of forming a liner layer, a low frequency RF power and a high frequency RF power are provided simultaneously to the first source layer while the third reactant is provided, and the first source layer is dissociated and converted into a second source layer by the activated third reactant.
In one or more embodiment, the second phase of forming a deposition layer is comprised of providing a first reactant and forming a third source layer on the liner layer, and providing a second reactant to the third source layer.
In one or more embodiment, in the second phase of forming a deposition layer, a high frequency RF power is provided while the second reactant is provided, and forming a compound by reacting the third source layer with the activated second reactant.
In one or more embodiment, at least a part of the liner layer is converted into the compound by the activated second reactant. In one more embodiment, a loss of patterned structure by the activated second reactant is below 5 Å.
The above and other aspects, features, and advantages of certain embodiments of the disclosure will be more apparent from the following description taken in conjunction with the accompanying drawings, in which:
The disclosure relates to a method to solve the above-mentioned problems, and more specifically relates to a method of forming a liner layer having a thin thickness as a protective layer to minimize damage to an underlayer.
In the embodiment of the disclosure, dual frequency RF power may be provided to form a liner layer on a carbon-containing photo resist layer. More specifically, the liner layer may be formed by simultaneously providing a low frequency RF power and a high frequency RF power. The supply of low frequency RF power may have a technical advantage in that the density and the hardness of the liner layer may be improved, while minimizing the underlayer damage. The supply of high frequency RF power may have a technical advantage of promoting radical generation and achieving a high uniformity and a high film growth rate.
A first step S1: a substrate is loaded into a reactor. The substrate may include a patterned structure formed thereon and the patterned structure may comprise a carbon-containing photo resist.
A second step S2: a first source layer may be formed by supplying a first reactant. The first reactant may be a silicon-containing gas. For instance, the first reactant may comprise at least one of aminosilane, iodosilane, or halide. The first source layer may be formed by adsorbing the first reactant on the photo resist. And a third reactant may be continuously provided together throughout the process, that is, throughout the second step to the eighth step. The third reactant may comprise an inert gas such as Ar, He, or N2. The third reactant may carry the first reactant to the substrate or facilitate the uniform supply of the first reactant to the reaction space.
A third step S3: a low frequency RF power and a high frequency RF power are provided simultaneously, resulting in activation of the third reactant.
A fourth step S4: The activated third reactant may dissociate the first source layer adsorbed on the photo resist. The dissociated first source layer may then be converted into a second source layer. The second source layer may consist of fragments of molecules of the first reactant. For instance, when an aminosilane source gas (as a first reactant) is provided and adsorbed on the photo resist as the first source layer, the second source layer may contain individual silicon elements, carbon elements, nitrogen elements, hydrogen elements, and fragments of ligands (such as alkyl group). The first source layer may be dissociated and converted into the second source layer, and the second source layer may be densified on the photo resist due to the ion bombardment effect of the activated third reactant.
The second step S2 to the fourth step S4 may be repeated a plurality of times, for instance, M times, and the third reactant may be continuously provided throughout the second step S2 to the fourth step S4. The second step S2 to the fourth step S4 may be referred to as the phase for forming a liner layer. The liner layer may be a protective layer to protect the photo resist underlayer from active species in the following phase for forming a deposition layer. In an exemplary embodiment, a purge step may be provided between the second step S2 and the third step S3, and between the third step S3 and the fourth step S4.
A fifth step S5: a third source layer may be formed on the second source layer by supplying the first reactant thereto. The first reactant may be a silicon-containing gas and may comprise at least one of aminosilane, iodosilane, or halide. The third source layer may be formed by adsorbing the first reactant on the second source layer. The third source layer may be the same material as the first source layer and the third reactant may be supplied together. The third reactant may be an inert gas such as Ar or N2, and may carry the first reactant to the substrate and facilitate the uniform supply of the first reactant in the reaction space.
A sixth step S6: a second reactant may be provided to the reactor. The second reactant may not chemically react with the third source layer, but may chemically react with the third source layer when it is activated. Thus, the second reactant may be referred to as a reactive purge gas.
In one embodiment of the disclosure, the second reactant may contain oxygen. For instance, the second reactant may comprise least one of O2, CO2, N2O, NO2, O3, H2O, or the mixture thereof.
In another embodiment of the disclosure, the second reactant may contain nitrogen. For instance, the second reactant may comprise at least one of N2, N2O,NO2, NH3, N2H2, N2H4, or the mixture thereof. The third reactant may be continuously provided from the sixth step S6 to the seventh step S7.
A seventh step S7: high frequency RF power may be provided to the reactor. The high RF power may activate the second reactant. In alternative embodiment, a low frequency RF power and a high frequency RF power may be provided together.
An eight step S8: the activated second reactant and the third source layer chemically react with each other and form a deposition layer on the second source layer. In one embodiment, the deposition layer may be a patterning layer such as silicon oxide (SiOx) layer or silicon nitride (SixNy) or any insulating material layer. In another embodiment, the sixth step S6 to the eight step S8 may be carried out simultaneously.
The fifth step S5 and the eight step S8 may be repeated a plurality of times, for instance, N times, and the third reactant may be continuously provided throughout the second step S5 to the fourth step S8. The fifth step S5 to the eight step S8 may be referred to as the phase for forming a deposition layer. In a selective embodiment, a purge step may be provided between the fourth step S4 and the fifth step S5, and between the fifth step S5 and the sixth step S6, and between the sixth step S6 and the seventh step S7, and between seventh step S7 and the eight step S8, and after the eight step S8. In another embodiment, the second reactant and the third reactant may be continuously provided throughout the fifth step S5 to the eight step S8.
A ninth step S9: after the first step S1 to S4, that is, a phase for forming a liner layer, and the fifth step S5 to the eight step S8, that is, a phase for forming a deposition layer are completed, the substrate processing process may end.
According to the embodiment of the disclosure described in
A first phase of
A second phase of
The first reactant provided during the timing steps T1 and T5 may contain silicon (Si) such as aminosilane, iodosilane, or halide. For instance, the first reactant may comprise: at least one of TSA, (SiH3)3N; DSO, (SiH3)2; DSMA, (SiH3)2NMe; DSEA, (SiH3)2NEt; DSIPA, (SiH3)2N(iPr); DSTBA, (SiH3)2N(tBu); DEAS, SiH3NEt2; DTBAS, SiH3N(tBu)2; BDEAS, SiH2(NEt2)2; BDMAS, SiH2(NMe2)2; BTBAS, SiH2(NHtBu)2; BITS, SiH2(NHSiMe3)2; DIPAS, SiH3N(iPr)2; TEOS, Si(OEt)4; SiCl4; HCD, Si2Cl6; 3DMAS, SiH(N(Me)2)3; BEMAS, SiH2[N(Et)(Me)]2; AHEAD, Si2(NHEt)6; TEAS, Si(NHEt)4; Si3H8 ; DCS, SiH2Cl2; SiHl3; SiH2l2; or the mixture or derivatives thereof.
Thus, a SiCN liner layer as a protective layer may be formed on the photo resist during the first phase according to embodiments of
The second reactant provided during the timing steps T2 and T5 of
The third reactant provided during the timing steps T1 to T8 may be an inert gas. For instance, the third reactant may comprise at least one of Ar, He, or N2 or the mixture thereof.
The high frequency RF power provided during the phase for forming a liner layer may increase the ion density of the activated third reactant (such as Ar ions) and the low frequency RF power provided together may contribute to the film densification of the liner layer due to the ion bombardment effect. As a result, it contributes to minimizing damage to the underlying layer of the photoresist. Thus, the substrate processing method according to the disclosure may have a technical advantage in that: (1) the liner layer may be densified due to increased ion density; (2) the film conformality on the patterned structure may improve, and (3) the underlayer damage may decrease by providing the high frequency RF power and the low frequency RF power simultaneously.
According to the embodiment of
In
In
In
In
In addition, when the SiCN liner layer is thicker, for instance, 20 Å, and the SiCN liner layer is formed by providing only a high frequency RF power or a high frequency RF power and a low frequency RF power together, followed by forming SiO2 patterning layer thereon by PEALD, the underlayer loss may be less than 5 Åand 1 Å,respectively. That is, below 5 Å, thus the underlayer loss may be controlled below the range that does not affect the device performance.
In step 1 of
In step 2 of
In step 3 of
In step 4 of
Table 1 shows a process condition for SiCN liner layer and SiO2 deposition layer according to one embodiment of disclosure.
In
The process gas is exhausted through an exhaust unit 80, which may be an exhaust pump. The gas supply unit 20 is connected to the RF power supply unit. The RF power supply unit may comprise: a matching network 50, a high frequency RF power generator 60, and/or a low frequency RF power generator 70. The RF power may be provided to the reactor and the intensity of RF power according to the disclosure may be controlled by step by programmable control unit such as PC controller (not shown).
It should be understood that embodiments described herein should be considered in a descriptive sense only and not for purposes of limitation. Descriptions of features or aspects within each embodiment should typically be considered as available for other similar features or aspects in other embodiments. While one or more embodiments have been described with reference to the figures, it will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope of the disclosure as defined by the following claims.
This application claims priority to U.S. Provisional Pat. Application Serial No. 63/334,838 filed Apr. 26, 2022 titled SUBSTRATE PROCESSING METHOD, the disclosure of which is hereby incorporated by reference in its entirety.
Number | Date | Country | |
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63334838 | Apr 2022 | US |