Method for filling a gap in a three-dimensional structure on a semiconductor substrate
This application relates to a method of filling a gap in a three-dimensional structure over a semiconductor substrate. The method may include depositing a thin film at least on a three-dimensional structure over a substrate using at least one reaction gas activated with a first radio frequency (RF) power having a first frequency, the three dimensional structure comprising a trench and/or hole. The method may also include etching the deposited thin film using at least one etchant activated with a second RF power having a second frequency lower than the first frequency. The method may further include repeating a cycle of the depositing and the etching at least once until the trench and/or hole are filled with the thin film. According to some embodiments, a thin film having substantially free of voids and/or seams can be formed in the three-dimensional structure.
1 . A method of filling a gap in a three-dimensional structure on a substrate, the method comprising:
depositing a thin film for filling the gap in the three-dimensional structure using a reaction gas activated with a first radio frequency (RF) power having a first frequency to form a deposited thin film;
performing an etching process, the etching process comprising an etching step and a purge step after the etching step, wherein the etching step comprises providing an etchant comprising fluorine and activating the etchant with a second RF power having a second frequency lower than the first frequency, wherein the deposited thin film is etched during the etching step, wherein the etchant is continuously provided during the etching step, wherein the second frequency is in a range of about 3 kHz to about 1,000 kHz; and
repeating a cycle of the depositing and the etching at least once to form a thin film pattern that fills the gap to a level above a top surface the structure,
wherein the deposited thin film formed on the top surface of the structure and a top portion of the gap are etched more than the deposited thin film formed on a middle surface of the gap and a lower surface of the gap, and
wherein a ratio of voids to material in a volume of the thin film is 0.005 or less.
2 . The method of claim 1 , wherein the reaction gas comprises at least one of O 2 , O 3 , H 2 O, NO 2 , N 2 O, or any combination thereof.
3 . The method of claim 1 , wherein the first frequency is in a range of about 500 MHz to about 3,000 MHz.
4 . The method of claim 1 , wherein the first RF power is in a range of about 1,000 watt to about 3,000 watt.
5 . The method of claim 1 , wherein the deposited thin film formed on the middle surface of the gap is etched more than the deposited thin film formed on the lower surface of the gap.
6 . The method of claim 1 , wherein the second RF Power is in a range of about 100 watts to about 500 watts.
7 . The method of claim 1 , wherein the first frequency is in a range of about 27.12 MHz to about 100 MHz, and wherein the second frequency is in a range of about 100 kHz to about 1,000 kHz.
8 . The method of claim 1 , wherein the etchant comprises at least one of F 2 , CF 4 , or any combination thereof.
9 . The method of claim 1 , wherein depositing the thin film comprises providing a precursor comprises one or more of an aminosilane, an iodosilane, or a silicon halide.
10 . The method of claim 1 , further comprising supplying an inhibitor activated with a plasma gas before depositing the thin film, wherein the inhibitor comprises nitrogen.
11 . The method of claim 1 , wherein depositing the thin film comprises forming a plasma from a gas consisting of Ar and one or more of O 2 , O 3 , H 2 O, NO 2 , and N 2 O, and wherein the etchant consists of one or more of NF 3 , ClF 3 , F 2 , SF 6 , and CF 4 .
12 . The method of claim 1 , wherein the method is performed at a pressure in the range of about 1 Torr to about 5 Torr.
13 . The method of claim 1 , wherein the reaction gas is continuously provided during the step of depositing the thin film.
14 . The method of claim 1 , wherein the gap has an aspect ratio of at least about 20:1.
15 . The method of claim 14 , wherein the cycle of the depositing and the etching is repeated 1-40 times when a width of the gap is about 100 nm or less.
16 . A method of filling a gap in a three-dimensional structure over a semiconductor substrate, the method comprising:
depositing a thin film comprising SiO 2 for filling the gap in the three-dimensional structure by a vapor deposition process comprising contacting the three-dimensional structure with a reaction gas activated with a first radio frequency (RF) power having a first frequency to form a deposited thin film;
etching the deposited thin film using an etchant activated with a second RF power having a second frequency in a range of about 3 kHz to about 1,000 kHz, wherein the second frequency is different from the first frequency, wherein the etchant comprises fluorine; and
repeating a cycle of the depositing and the etching at least once until the gap is filled with the thin film to form a thin film pattern.
17 . The method of claim 13 , wherein the depositing comprises activating the reaction gas with the first frequency in a range of about 100 kHz to about 3,000 MHz.
18 . The method of claim 16 , further comprising continuously flowing a carrier gas through the cycle of the depositing and the etching.
19 . The method of claim 16 , wherein depositing the thin film comprises forming a plasma from a gas consisting of Ar and one or more of O 2 , O 3 , H 2 O, NO 2 , and N 2 O, and wherein the etchant consists of one or more of NF 3 , ClF 3 , F 2 , SF 6 , and CF 4 .
20 . The method of claim 16 , wherein the deposited thin film formed on a middle surface of the gap is etched more than the deposited thin film formed on a lower surface of the gap.