Carbon-containing mask deposition method and substrate structure

Abstract

The invention discloses a carbon-containing mask deposition method and a substrate structure, belongs to the field of vapor deposition, and aims to solve the defect of hole or groove morphology in the etching process. Depositing a first series of layers containing a plurality of sub-layers and a second series of layers containing a plurality of sub-layers above the to-be-etched layer by changing reaction conditions, wherein the sub-layers of the first series of layers and the sub-layers of the second series of layers are crossed and stacked; a sub-layer of the first series of layers is made to have a different hardness than a sub-layer of the adjacent second series of layers. The method is mainly used for vapor deposition of the carbon-containing mask on the substrate.

Description

Technical Field

[0001] This invention relates to the field of vapor deposition technology, and more particularly to a carbon-containing mask deposition method and substrate structure. Background Technology

[0002] Microfabrication of semiconductor substrates is a well-known technique used to manufacture, for example, semiconductors, flat panel displays, light-emitting diodes (LEDs), and solar cells. A crucial step in microfabrication is the plasma processing step, which takes place inside a reaction chamber where process gases are introduced. An radio frequency source, coupled to the reaction chamber by inductance and / or capacitance, excites the process gases to form and maintain plasma. Deposition or etching processes are then performed on the substrate using plasma.

[0003] To etch specific patterns of semiconductor structures onto a device, a mask is used to transfer the pattern onto the device layer. However, during the transfer process, the mask, due to its inherent properties, is also consumed when subjected to plasma bombardment. Furthermore, the patterned area of ​​the mask is unevenly etched laterally, causing deviations in the etching of the device layer and severely affecting the etching accuracy of the device. Summary of the Invention

[0004] To address the technical problem of pattern degradation in the mask layer during etching, this invention provides a carbon-containing mask deposition method for depositing a mask on the layer to be etched, comprising the following steps:

[0005] The reactive gas is excited into plasma, and by changing the reaction conditions, a first series of layers containing multiple sub-layers and a second series of layers containing multiple sub-layers are deposited on the layer to be etched, wherein the sub-layers of the first series of layers and the sub-layers of the second series of layers are stacked crosswise.

[0006] The sublayers of the first series of layers have different hardness than the sublayers of the adjacent second series of layers.

[0007] Optionally, the sublayers of the first series of layers have different thicknesses from the sublayers of the adjacent second series of layers.

[0008] Optionally, the sublayers of the first series of layers and / or the sublayers of the second series of layers have the same hardness.

[0009] Optionally, the sublayers of the first series of layers and / or the sublayers of the second series of layers have the same thickness.

[0010] Optionally, the hardness of the sublayers of the first series of layers and the sublayers of the second series of layers can be adjusted by at least one of particle doping, radio frequency power, radio frequency frequency, temperature, and chamber pressure.

[0011] Optionally, the hardness of the sublayers of the first series of layers gradually increases from bottom to top, and / or the hardness of the sublayers of the second series of layers gradually increases from bottom to top.

[0012] Optionally, the thickness of the sublayers of the first series of layers gradually increases from bottom to top, and / or the thickness of the sublayers of the second series of layers gradually increases from bottom to top.

[0013] Optionally, the hardness and thickness of the sublayers of the first series of layers gradually increase from bottom to top, and / or the hardness and thickness of the sublayers of the second series of layers gradually increase from bottom to top.

[0014] Optionally, a sublayer of the first series of layers is deposited on top of the layer to be etched, and then a sublayer of the second series of layers is deposited. The sublayers of the first series of layers have the same hardness and thickness, and at least one sublayer of the second series of layers is a stacked layer with different hardness.

[0015] Optionally, the hardness of the superimposed layer gradually increases, or the hardness of the superimposed layer gradually decreases, or the hardness of the superimposed layer first increases and then decreases.

[0016] Optionally, each sublayer of the second series layer is a double-layered stack of two different hardnesses.

[0017] Optionally, the upper and lower layers of the double-layer stacked layer have the same thickness, or the upper layer of the double-layer stacked layer has a greater thickness than the lower layer.

[0018] Optionally, the hardness of the upper layer of the double-layer stack gradually increases, and / or the thickness of the upper layer of the double-layer stack gradually increases.

[0019] Optionally, the upper layer of each double-layer stack has the same thickness but different hardness; or the upper layer of each double-layer stack has the same thickness and the same hardness; or the upper layer of each double-layer stack has different thicknesses but the same hardness.

[0020] Optionally, a sublayer of the first series of layers is deposited on top of the layer to be etched, and then a sublayer of the second series of layers is deposited. The sublayers of the first series of layers have different hardness and thickness, and at least one sublayer of the second series of layers is a stacked layer with different hardness.

[0021] Optionally, the sublayers of the first series of layers and the sublayers of the second series of layers are amorphous carbon layers.

[0022] Optionally, the method further includes depositing a protective layer on the top layer of the carbon mask, wherein the hardness of the sub-layers of the first series layers and the second series layers is greater than that of the sub-layers of the second series layers, and the protective layer is an amorphous carbon layer.

[0023] Furthermore, the present invention also provides a substrate structure, comprising:

[0024] A substrate on which the layer to be etched as described above is formed;

[0025] A carbon mask is formed on the layer to be etched using any of the carbon mask deposition methods described above.

[0026] Optionally, the layer to be etched includes at least one of silicon oxide, silicon nitride, and polycrystalline silicon, or an alternating cycle of at least two of silicon oxide, silicon nitride, and polycrystalline silicon.

[0027] At least one of the above technical solutions has the following advantages or beneficial effects: By stacking a series of carbon-containing materials with different hardness, the overall selection ratio of the mask layer is made suitable for the requirements of the etching process, and the stress inside the mask layer can be relieved, ensuring the stability of the mask layer properties. At the same time, the thickness and hardness of the sub-layers of the series of layers can be flexibly adjusted and varied according to different etching conditions and requirements to meet the requirements of different processes on the mask layer structure, ensuring the precise etching dimensions and morphology of the layer to be etched. Attached Figure Description

[0028] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0029] Figure 1A-1C This is a schematic diagram illustrating the typical process of localized etching of a substrate.

[0030] Figure 2 A schematic diagram of the mask structure formed using the carbon-containing mask deposition method of this application;

[0031] Figure 3 This is a schematic diagram of a mask structure formed using another carbon-containing mask deposition method described in this application. Detailed Implementation

[0032] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0033] The carbon-containing mask deposition method of the present invention utilizes two series of mask layers with different hardnesses to be stacked in a cycle. This not only allows for flexible adjustment of the overall hardness of the mask, enabling it to adapt to different etching processes while ensuring the integrity of the pattern, but also balances the stress of the mask layer under high hardness, thus stabilizing the mechanical strength of the mask layer and preventing it from cracking due to stress concentration during subsequent etching processes.

[0034] like Figure 1A-1C The image shown is a simplified schematic diagram of the etching process, capturing a partial side view of the substrate. Figure 1A The process includes a substrate 1, a layer 2 to be etched deposited on the substrate 1, and a mask layer 3 deposited on the layer 2. To etch a hole or trench structure in the layer 2, such as... Figure 1B As shown, the pattern needs to be transferred onto mask layer 3 using a photolithography process first. For example... Figure 1C As shown, a plasma etching process is used to transfer the pattern on the mask layer 3 onto the layer 2 to be etched. However, during the plasma etching process, the mask layer 3 is also etched away. As the depth of the etched holes in the layer 2 increases, the mask layer 3 has already formed a pattern before the etching is complete. Figure 1C The morphological defects shown, such as the sloping surface of the enlarged opening due to its proximity to the plasma at the top of the mask layer, or the curved surface on the sidewall of the mask layer 3 due to the reflection of etching particles, all indirectly affect the dimensional accuracy or morphology of the holes or grooves in the underlying layer 2 to be etched. The ratio of the consumption rate of the mask layer 3 to that of the layer 2 to be etched is called the selectivity ratio. To ensure the dimensional accuracy of the holes or grooves in the layer 2 to be etched, a higher selectivity ratio is better.

[0035] However, increasing the selectivity by increasing the hardness of the mask layer 3 cannot be done indefinitely. When the hardness of the mask layer 3 reaches a certain level, it will generate excessively concentrated stress. This stress will cause cracks in the mask layer 3 due to temperature changes during subsequent etching, affecting the pattern transfer function of the mask layer 3.

[0036] like Figure 2 As shown, the mask layer 100 formed using this invention is mainly composed of carbon-containing materials, such as amorphous carbon, diamond-like carbon, etc. Plasma-enhanced chemical vapor deposition (PECVD) can be used to better control the uniformity and density of the film layer.

[0037] The deposition method of the present invention for forming a carbon-containing mask mainly includes the following steps:

[0038] The reactive gas is excited into plasma, and by changing the reaction conditions, a first series of layers 110 containing multiple sublayers and a second series of layers 120 containing multiple sublayers are deposited above the layer to be etched 200. The sublayers of the first series of layers 110 and the sublayers of the second series of layers 120 are stacked alternately. Figure 2In the illustrated embodiment, the first series of layers 110 includes sublayers 111, 112, and 113, and the second series of layers 120 includes sublayers 121, 122, and 123. Taking this as an example, the intermediate multi-layer cycles are omitted without limiting the number of cycles. Sublayer 111 is deposited using one reaction condition, followed by sublayer 121 deposited using another reaction condition. This process is repeated with the deposition of sublayers from the first series of layers 110 and the second series of layers 120. The different reaction conditions result in sublayers from the first series of layers 110 having different hardnesses than the adjacent sublayers from the second series of layers.

[0039] The reactant gas may include carbon-containing gases, alkanes (methane, ethane, propane, butane, pentane, octane, nonane, decane and their isomers), alkenes (propylene, ethylene, butene, pentene and their isomers), dienes (hexadiene, butadiene, isoprene, pentadiene and their isomers), alkynes (acetylene, vinylacetylene and their isomers), aliphatic hydrocarbons (cyclopropane, cyclobutane, cyclopentane, cyclopentadiene, toluene and their isomers), and aromatic hydrocarbons (benzene, styrene, toluene, xylene, pyridine, ethylbenzene, acetophenone and their isomers), but is not limited to one or more of the above gases. The flow rate of this hydrocarbon gas can be adjusted between 100 sccm and 5000 sccm.

[0040] The first series of layers 110 and the second series of layers 120 each have independent characteristics. Their sublayers either have the same reaction conditions, or the reaction conditions vary according to a unified rule, or the sublayers they form have the same characteristics, or the sublayers they form have the same variation rules. Alternating layers with varying hardness can release the stress at the boundaries between sublayers of different hardness. Furthermore, the hardness of a series of mask layers can be increased to ensure that the hardness of the entire mask layer 100 meets the selectivity requirements of the etching process. As the aspect ratio of the vias on the layer to be etched 200 gradually increases, the etching process becomes increasingly complex. While ensuring overlapping deposition, the hardness of each series of sublayers can be independently adjusted to adapt to different etching process conditions, ensuring the selectivity and morphology of the mask layer.

[0041] In some embodiments, the sublayers of the first series layers 110 and the adjacent sublayers of the second series layers 120 may have different thicknesses. Changing the thickness can simultaneously adjust the hardness distribution in the vertical direction of the mask layer 100 and optimize stress dissipation within the mask layer. In the technical solution of the present invention, the hardness of the sublayer can be adjusted by doping the sublayer with particles during deposition, such as at least one of W, Mo, B, Si, and N, or by changing the reaction conditions for depositing the sublayer, such as at least one of radio frequency power, radio frequency frequency, temperature, and chamber pressure. The thickness of the sublayer can be adjusted by controlling the deposition time or the content of the reactant gas.

[0042] In some embodiments, to reduce certain degrees of freedom and better control the overall performance of the mask layer 100, the sublayers of the first series of layers 110 can have the same hardness. For example, sublayers 111, 112, and 113 have the same hardness, while sublayers 121, 122, and 123 have different hardnesses. Alternatively, the sublayers of the second series of layers 120 can have the same hardness. For example, sublayers 111, 112, and 113 have different hardnesses, while sublayers 121, 122, and 123 have the same hardness. Or, the sublayers included in the first series of layers 110 and the second series of layers 120 can each have the same hardness. For example, sublayers 111, 112, and 113 have the same hardness, and sublayers 121, 122, and 123 have the same hardness. After determining the hardness arrangement, the thickness of the sublayers can be adjusted according to the types of defects that occur during the process of non-layered masks in the prior art. For example, the sublayers of the first series of layers 110 can have the same thickness, while the sublayers of the second series of layers 120 can have different thicknesses; or the sublayers of the first series of layers 110 can have different thicknesses, while the sublayers of the second series of layers 120 can have the same thickness; or the sublayers of the first series of layers 110 can have the same thickness, while the sublayers of the second series of layers 120 can have the same thickness. The specific thickness and hardness values ​​can be adjusted based on the types of defects that occur when performing the process on a non-layered mask in the prior art. For example, the hardness can be increased at locations prone to sidewall curvature, and the thickness can be matched to the upper and lower boundaries of the curvature. In other embodiments, the hardness arrangement can also be changed when the sublayer thickness arrangement is determined.

[0043] In the above embodiments, when the sublayers of the first series layer 110 and / or the sublayers within the second series layer 120 have different hardness, the different hardness can be set to gradually increase from bottom to top. The increased hardness of the upper sublayers can resist plasma etching for a longer time, better ensuring the morphology of the layer to be etched below. When the sublayers of the first series layer 110 and / or the sublayers within the second series layer 120 have different thicknesses, the different thicknesses can be set to gradually increase from bottom to top. The sublayers closer to the top are less sensitive to stress concentration and can be made into relatively thick hard mask layers. At the same time, the hardness and thickness of the sublayers of the first series layer 110 can also be set to gradually increase from bottom to top, and the same applies to the second series layer 120.

[0044] In another embodiment, such as Figure 3As shown, the difference from the above embodiment is that a sublayer 111 of a first series layer 110 is deposited first above the layer to be etched 200, followed by a sublayer 221 of a second series layer 220. The sublayers 111, 112, and 113 of the first series layer 110 have the same hardness and thickness. At least one sublayer 221 of the second series layer 220 is a stacked layer with different hardnesses. For example, a double-layer stacked layer 221 includes two stacked sublayers 2211 and 2212 with different hardnesses. The hardness of the stacked sublayers 2211 and 2212 can gradually increase or decrease from bottom to top. In embodiments containing more than two stacked sublayers, the hardness of the stacked sublayers can also increase first and then decrease from bottom to top.

[0045] In embodiments with only two stacked sublayers, each sublayer of the second series of layers can be a double-stacked layer, such as... Figure 3 As shown, the second series of layers 220 includes stacked sublayers 2211, 2212, 2221, 2222, 2231, and 2232. Depending on the aforementioned different process conditions, the upper and lower layers of the double-layer stack can be of the same thickness, or the upper layer of the double-layer stack can be thicker than the lower layer. In other embodiments, the properties of the upper layer of the double-layer stack can also vary independently. For example, the hardness and / or thickness of the stacked sublayers 2212, 2222, and 2232 can be the same, or the hardness and / or thickness of the stacked sublayers 2212, 2222, and 2232 can gradually increase. Simultaneously, the hardness or thickness of the stacked sublayers 2212, 2222, and 2232 can be the same, while the other property is different.

[0046] In the above embodiments, the main body of the carbon-containing mask can be made of amorphous carbon material, such as sublayers of the first series layers and sublayers of the second series layers. To further improve the overall selectivity of the mask layer 100, a protective layer with a hardness greater than that of the sublayers of the first series layers and the second series layers can also be deposited on the top layer of the mask layer, also using amorphous carbon material.

[0047] The technical solution of the present invention further provides a substrate structure, as shown in FIG1, including a substrate 300, a layer to be etched 200, and a mask layer 100 formed above the layer to be etched 200 using the above method. The layer to be etched can be at least one of silicon oxide, silicon nitride, and polycrystalline silicon, or an alternating cycle of at least two of silicon oxide, silicon nitride, and polycrystalline silicon. The substrate 300 can be selected from materials such as silicon, silicon carbide, and sapphire. In other embodiments, other material layers may also be present between the substrate 300 and the layer to be etched 200, and between the layer to be etched 200 and the mask layer 100.

[0048] The carbon-containing mask deposition method disclosed in this invention is not limited to being performed using a plasma-enhanced chemical vapor deposition (PECVD) apparatus, but can also be performed using a plasma-enhanced atomic layer deposition (PEALD) apparatus. During the plasma deposition stage, a single radio frequency (RF) or dual RFs can be used. The higher-frequency RF can have a frequency greater than or equal to 13.56 MHz and a power range of 100W-3000W; the lower-frequency RF can have a frequency less than or equal to 2 MHz and a power range of 50W-3000W.

[0049] Although the present invention has been described in detail through the preferred embodiments above, it should be understood that the above description should not be considered as a limitation of the present invention. Various modifications and substitutions to the present invention will be apparent to those skilled in the art after reading the above description. Therefore, the scope of protection of the present invention should be defined by the appended claims.

Claims

1. A carbon-containing mask deposition method for depositing a mask on a layer to be etched, characterized in that, comprising the steps of: exciting a reaction gas into a plasma, depositing a first series of layers comprising a plurality of sub-layers and a second series of layers comprising a plurality of sub-layers over the layer to be etched by varying the reaction conditions, the sub-layers of the first series of layers being cross-stacked with the sub-layers of the second series of layers; the sub-layers of the first series of layers and the adjacent sub-layers of the second series of layers have different hardness.

2. The carbon-containing mask deposition method of claim 1, wherein, the sub-layers of the first series of layers and the adjacent sub-layers of the second series of layers have different thickness.

3. The carbon-containing mask deposition method of claim 2, wherein, the sub-layers of the first series of layers and / or the sub-layers of the second series of layers have the same hardness.

4. The carbon-containing mask deposition method of claim 2, wherein, the sub-layers of the first series of layers and / or the sub-layers of the second series of layers have the same thickness.

5. The carbon-containing mask deposition method of claim 1, wherein, the hardness of the sub-layers of the first series of layers and the sub-layers of the second series of layers is adjusted by at least one of the following: particle doping, radio frequency power, radio frequency frequency, temperature, chamber pressure.

6. The carbon-containing mask deposition method of claim 1, wherein, the hardness of the sub-layers of the first series of layers gradually increases from bottom to top, and / or the hardness of the sub-layers of the second series of layers gradually increases from bottom to top.

7. The carbon-containing mask deposition method of claim 1, wherein, the thickness of the sub-layers of the first series of layers gradually increases from bottom to top, and / or the thickness of the sub-layers of the second series of layers gradually increases from bottom to top.

8. The carbon-containing mask deposition method of claim 1, wherein, the hardness and thickness of the sub-layers of the first series of layers gradually increase from bottom to top, and / or the hardness and thickness of the sub-layers of the second series of layers gradually increase from bottom to top.

9. The carbon-containing mask deposition method of claim 1, wherein, a sub-layer of the first series of layers is deposited over the layer to be etched, followed by a sub-layer of the second series of layers, the sub-layers of the first series of layers having the same hardness and thickness, and at least one sub-layer of the second series of layers being a superimposed layer of different hardness.

10. The carbon-containing mask deposition method of claim 9, wherein, the hardness of the superimposed layer gradually increases, or the hardness of the superimposed layer gradually decreases, or the hardness of the superimposed layer first increases and then decreases.

11. The carbon-containing mask deposition method of claim 9, wherein, each sub-layer of the second series of layers is a double-layer superimposed layer of two different hardnesses.

12. The carbon-containing mask deposition method of claim 11, wherein, the thickness of the upper and lower layers of the double-layer superimposed layer is the same, or the thickness of the upper layer of the double-layer superimposed layer is greater than the thickness of the lower layer.

13. The carbon-containing mask deposition method of claim 12, wherein, the hardness of the upper layer of the double-layer superimposed layer gradually increases, and / or the thickness of the upper layer of the double-layer superimposed layer gradually increases.

14. The carbon-containing mask deposition method of claim 11, wherein, the thickness of the upper layer of each double-layer superimposed layer is the same, and the hardness is different; or the thickness of the upper layer of each double-layer superimposed layer is the same, and the hardness is the same; or the thickness of the upper layer of each double-layer superimposed layer is different, and the hardness is the same.

15. The carbon-containing mask layer deposition method of claim 1, wherein, a sub-layer of the first series of layers is deposited over the layer to be etched, followed by a sub-layer of the second series of layers, the sub-layers of the first series of layers having different hardness and thickness, and at least one sub-layer of the second series of layers being a superimposed layer of different hardness.

16. The carbon-containing mask deposition method of any of claims 1-15, wherein, the sub-layers of the first series of layers and the sub-layers of the second series of layers are amorphous carbon layers.

17. The carbon-containing mask deposition method of any of claims 1-15, wherein, further comprising depositing a protective layer with a hardness greater than the sub-layers of the first series of layers and the sub-layers of the second series of layers on the uppermost layer of the carbon-containing mask, the protective layer being an amorphous carbon layer.

18. A substrate structure, characterized by comprising: a substrate having a layer to be etched formed thereon as claimed in claim 1; a carbon-containing mask formed on the layer to be etched using the carbon-containing mask deposition method of any one of claims 1-17.

19. The substrate structure of claim 18, wherein, the layer to be etched comprises at least one of silicon oxide, silicon nitride, and polysilicon, or an alternating cycle of at least two of silicon oxide, silicon nitride, and polysilicon.

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