Method for optimizing the height load of multilayer film back etching

Abstract

The present invention provides a method for optimizing the back-etching height load of a multilayer thin film. The method comprises providing a substrate having a groove formed thereon; forming a functional thin film deposited and covering the inner wall of the surface of the groove; forming a sacrificial layer in the filled groove; synchronously back-etching the sacrificial layer and the functional thin film, exposing the functional thin film layer above the back-etched sacrificial layer, and removing the upper side of the functional thin film at the upper end of the groove; removing the back-etched sacrificial layer; repeatedly forming another layer of functional thin film covering the functional thin film, and repeating the steps of filling the sacrificial layer, back-etching the sacrificial layer and the functional thin film, and removing the back-etched sacrificial layer each time another layer of functional thin film is formed, to form a multilayer functional thin film of the same height on the inner wall surface of the groove. The present invention utilizes a sacrificial layer filled in the groove to etch multiple filling materials layer by layer, providing a solution to the effective filling and construction process requirements of multilayer thin films in deep trenches with high aspect ratios.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor technology, and in particular to a method for optimizing the height load of multi-layer thin film etching back. Background Art

[0002] During the multi-layer thin film etching back process, differences in film material lead to differences in the amount of etching performed, resulting in significant loading on the film height after etching. Addressing this loading issue across multiple films in a single process is a significant challenge. Multi-layer thin film etching back is often used in the fabrication of multifunctional metal gates. If high and low loading occur across multiple functional films, the gate connection contact window will experience unstable contact resistance, affecting the threshold voltage and potentially leading to short circuits and open circuits, directly impacting device performance.

[0003] To this end, a new type of back-etching method is needed to effectively reduce the height load between films, intelligently adjust the height of each layer of film, achieve effective contact between each layer of film and the upper structure, and truly demonstrate its functionality. Summary of the Invention

[0004] In view of the shortcomings of the prior art described above, the purpose of the present invention is to provide a method for optimizing the height load of multi-layer thin film back etching, which is used to solve the problem that the multi-layer thin film back etching process in the prior art is often used in the preparation of multi-functional layer metal gates. If high and low loads of the multi-layer functional film appear, the contact resistance will be unstable during the gate connection contact window process, affecting the threshold voltage, and even short circuit and open circuit will occur, which will directly affect the performance of the device.

[0005] To achieve the above and other related objectives, the present invention provides a method for optimizing the height load of multi-layer thin film back etching, comprising:

[0006] Step 1: providing a substrate, wherein a groove is formed on the substrate;

[0007] Step 2: forming a functional film covering the surface of the groove;

[0008] Step 3: filling the trench to form a sacrificial layer;

[0009] Step 4: synchronously etching back the sacrificial layer and the functional film, exposing the functional film layer above the sacrificial layer after the back etching, so that the upper side of the functional film at the upper end of the trench is etched away;

[0010] Step 5: removing the sacrificial layer after back-etching;

[0011] Step 6: forming another layer of functional film covering the functional film multiple times, and repeating steps 3 to 5 each time another layer of functional film is formed, so as to form multiple layers of functional films of the same height on the inner wall surface of the groove.

[0012] The trench in step 1 is a high aspect ratio trench.

[0013] The width of the groove in step 1 is 2 nanometers to 50 nanometers; the depth of the groove is less than 1 micrometer.

[0014] Preferably, the sacrificial layer in step three is an organic layer.

[0015] Preferably, the organic layer in step three is a spin-on carbon hard mask.

[0016] Preferably, the organic layer in step three is a bottom anti-reflective coating.

[0017] Preferably, the material of the functional film in step 2 is any one of aluminum, copper, tungsten, silicon dioxide, silicon nitride, titanium nitride and tantalum nitride.

[0018] Preferably, the back etching in step 4 is dry etching.

[0019] Preferably, the sacrificial layer in step six is ​​removed by ashing.

[0020] Preferably, the material of each layer of the multi-layer functional film in step seven is different.

[0021] As described above, the method for optimizing the back-etching height load of a multi-layer thin film according to the present invention has the following beneficial effects:

[0022] The present invention fills a sacrificial layer in the trench and etches multiple filling materials layer by layer to achieve ideal multi-layer film load improvement, providing a solution to the effective filling and construction process requirements of multi-layer films in deep trenches with high aspect ratios. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 Shown is a schematic diagram of the process flow of the present invention;

[0024] Figure 2 Shown is a partial schematic diagram of the substrate of the present invention;

[0025] Figure 3 Shown is a schematic diagram of the present invention after forming a functional film;

[0026] Figure 4 Shown is a schematic diagram of the present invention after the trench is filled with a sacrificial layer;

[0027] Figure 5Shown is a schematic diagram of the present invention after etching back the sacrificial layer and the functional film;

[0028] Figure 6 Shown is a schematic diagram of the present invention after the sacrificial layer is removed;

[0029] Figure 7 A schematic diagram showing the formation of a new functional thin film layer according to the present invention;

[0030] Figure 8 Shown is a schematic diagram of the present invention refilling the trench;

[0031] Figure 9 It is a schematic diagram showing the formation of a multi-layer functional film according to the present invention.

[0032] Reference numerals:

[0033] Substrate-10

[0034] Functional film-11

[0035] Sacrificial layer-12 DETAILED DESCRIPTION

[0036] The following describes the embodiments of the present invention through specific examples. Those skilled in the art will readily understand the other advantages and benefits of the present invention from the disclosure herein. The present invention may also be implemented or applied through various other specific embodiments, and the details in this specification may be modified or altered based on different viewpoints and applications without departing from the spirit of the present invention.

[0037] See also Figure 1 The present invention provides a method for optimizing the height load of multi-layer thin film back etching, comprising:

[0038] Step 1, see Figure 2 , providing a substrate 10, wherein a groove is formed on the substrate 10;

[0039] The trench in step 1 is a high aspect ratio trench.

[0040] In one possible embodiment, the width of the trench in step 1 is 2 nanometers to 50 nanometers; the depth of the trench is less than 1 micrometer, which is a high aspect ratio trench.

[0041] In another possible embodiment, the trench in step 1 is a non-high aspect ratio trench.

[0042] Step 2, please refer to Figure 3, a functional film 11 is deposited on the inner wall of the trench. During the multi-layer film etching back process, due to the difference in film material, there are differences in the etching amount during the etching back process. After etching, there is a large load on the film height. Solving the load problem between multiple films in a one-step process will be a great challenge. Therefore, only one layer of functional film 11 is generated here. By controlling the height of each layer of functional film 11, the multi-layer films 11 can be kept at the same height.

[0043] In one possible embodiment, the material of the functional film 11 in step 2 is any one of aluminum, copper, tungsten, silicon dioxide, silicon nitride, titanium nitride and tantalum nitride. It should be understood that the material of the functional film 11 here is determined by actual production and can also be other types of materials, which are not specifically limited here.

[0044] Step 3, please refer to Figure 4 , forming a sacrificial layer 12 in the trench filling, and by controlling the depth of the sacrificial layer 12 etched back, a portion of the functional film 11 can be exposed to a corresponding depth;

[0045] In one possible implementation, in smaller process technology nodes, such as process nodes of 14 nm and below, if conventional photoresist is used to fill the trenches, it is difficult to completely fill the trenches due to the low fluidity of the photoresist. Therefore, the sacrificial layer 12 in step three is an organic layer with good fluidity. The organic layer can be a carbon spin-on hard mask or a bottom anti-reflective coating. The carbon spin-on material and the bottom anti-reflective coating have good fluidity and can completely fill the trenches.

[0046] In another possible embodiment, the trench in step 1 is a trench without a high aspect ratio, and a material with relatively low fluidity may be used as the sacrificial layer 12 .

[0047] Step 4, please refer to Figure 5 , the sacrificial layer 12 and the functional film 11 are etched back synchronously, and the etching depth of the functional film 11 is controlled by the depth of the sacrificial layer 12 being etched back. The functional film 11 above the sacrificial layer 12 is exposed after the etched back, so that the upper side of the functional film 11 at the upper end of the groove is etched away. When the sacrificial layer 12 is etched back to a certain depth, the functional film 11 on the upper side of the sacrificial layer 12 will also be exposed, and the exposed functional film 11 will also be etched away. The exposed depth is the part that needs to be etched away, and the specific depth is determined according to the actual process requirements; please refer to Figure 6 , and back-etch the exposed functional film 11, thereby forming a layer of functional film 11 that meets the requirements on the inner wall of the groove. The depth of the sacrificial layer 12 can be etched to control the portion of the etched functional film 11, thereby avoiding the etching selectivity to load problem in the prior art.

[0048] In a possible implementation manner, the etch-back in step 4 is dry etching.

[0049] Step 5, please refer to Figure 6 , removing the sacrificial layer 12 after being etched back;

[0050] In a possible implementation manner, the sacrificial layer 12 in step six is ​​organic and can be removed by ashing.

[0051] Step 6, please refer to Figure 7 , forming another layer of functional film 11 covering the functional film 11 multiple times, repeating steps 3 to 5 each time another layer of functional film 11 is formed, forming a new functional film 11 on the inner wall surface of the groove, and after refilling the groove with the sacrificial layer 12, forming Figure 8 In the structure shown, a multilayer functional film 11 is formed on the inner wall surface of the groove. When etching each subsequent layer of functional film 11, since the etched functional film 11 is protected by the sacrificial layer 12, the etched portion of the newly generated functional film 11 can be controlled by controlling the height of the etched sacrificial layer 12. By adjusting the height of each layer of functional film 11, each layer of functional film 11 can be at the same height, and the following can be obtained: Figure 9 The structure shown achieves effective contact between each layer of film and the upper structure.

[0052] In a possible embodiment, the material of each layer of the multi-layer functional film 11 in step six is ​​different.

[0053] It should be noted that the illustrations provided in this embodiment are only used to schematically illustrate the basic concept of the present invention. Therefore, the illustrations only show components related to the present invention and are not drawn according to the number, shape and size of components in actual implementation. In actual implementation, the type, quantity and proportion of each component can be changed at will, and the component layout type may also be more complicated.

[0054] In summary, by filling trenches with sacrificial layers and etching multiple filler materials layer by layer, ideally improving the loading capacity of multilayer films is achieved. This provides a solution for the efficient filling and construction of multilayer films within deep trenches with high aspect ratios. Therefore, this invention effectively overcomes the shortcomings of existing technologies and possesses high industrial applicability.

[0055] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the present invention. Anyone skilled in the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by one of ordinary skill in the art without departing from the spirit and technical principles disclosed herein are intended to be covered by the claims of the present invention.

Claims

1. A method for optimizing the height load of multi-layer thin film back etching, characterized in that: At least: Step 1: providing a substrate, wherein a groove is formed on the substrate; Step 2: forming a functional film covering the surface of the groove; Step 3: filling the trench to form a sacrificial layer; Step 4: synchronously etching back the sacrificial layer and the current outermost functional film to a predetermined depth, so as to control the etching depth of the current outermost functional film by controlling the back-etching depth of the sacrificial layer, and exposing the functional film layer above the sacrificial layer after the back-etching, so that the upper side of the current outermost functional film at the upper end of the groove is etched away; Step 5: removing the sacrificial layer after back-etching; Step 6. After completing step 5 of the previous functional film, another layer of functional film is formed multiple times to cover the previous functional film. Each time another layer of functional film is formed, steps 3 to 5 are repeated for the newly formed functional film. By repeating the etching depth control of step 4 for each layer of functional film formed, multiple layers of functional films with the same final height are formed on the inner wall surface of the groove.

2. The method for optimizing the height load of multi-layer thin film back etching according to claim 1, characterized in that: The trench in step 1 is a high aspect ratio trench.

3. The method for optimizing the height load of multi-layer thin film back etching according to claim 2, characterized in that: The width of the groove in step 1 is 2 nanometers to 50 nanometers; the depth of the groove is less than 1 micrometer.

4. The method for optimizing the height load of multi-layer thin film back etching according to claim 2, characterized in that: The sacrificial layer in step three is an organic layer.

5. The method for optimizing the height load of multi-layer thin film back etching according to claim 4, characterized in that: The organic layer in step three is a spin-on carbon hard mask.

6. The method for optimizing the height load of multi-layer thin film back etching according to claim 4, characterized in that: The organic layer in step three is a bottom anti-reflective coating.

7. The method for optimizing the height load of multi-layer thin film back etching according to claim 1, characterized in that: The back etching in step 4 is dry etching.

8. The method for optimizing the height load of multi-layer thin film back etching according to claim 1, characterized in that: The material of the functional film in step 2 is any one of aluminum, copper, tungsten, silicon dioxide, silicon nitride, titanium nitride and tantalum nitride.

9. The method for optimizing the height load of multi-layer thin film back etching according to claim 3, characterized in that: The sacrificial layer in step six is ​​removed by ashing.

10. The method for optimizing the height load of multi-layer thin film back etching according to claim 1, characterized in that: The material of each layer of the multi-layer functional film in step seven is different.

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