Silicon nitride hard mask deposition method
By optimizing the silicon nitride hard mask deposition process, the problem of germanium-silicon layer defects caused by large differences in etching rate was solved, resulting in more uniform deposition and higher product yield.
Patent Information
- Application Number
- CN202511002292.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-07-18
- Publication Date
- 2025-11-04
AI Technical Summary
In existing technologies, silicon nitride hard masks exhibit large differences in in-plane etching rates during deposition, leading to defects in the germanium-silicon layer and affecting product yield.
The silicon nitride hard mask deposition process was optimized by turning off Plasma, controlling the film deposition temperature within the range of 570°C to 580°C, using pulsed and direct current DCS to alternately introduce the reactants, and increasing the NH3 introduction time.
It improves the deposition uniformity of silicon nitride hard masks, avoids defects in germanium-silicon layers, and improves product yield.
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Figure CN120895465A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the field of semiconductor manufacturing, in particular to a silicon nitride hard mask deposition method. BACKGROUND
[0002] Germanium silicon material can be used to manufacture high-speed heterojunction bipolar transistors (HBT), modulation doped field effect transistors (MODFET) and other devices.
[0003] The germanium silicon layer can be grown by ultra-high vacuum chemical vapor deposition (UHV / CVD): by UHV / CVD technology to grow a germanium silicon epitaxial layer on a silicon substrate, real-time doping growth can be realized. The growth of germanium silicon includes:
[0004] First step: grow a thin epitaxial germanium layer at low temperature (320-360℃) to suppress island growth of germanium and eliminate the effect of lattice mismatch.
[0005] Second step: continue to grow at a higher temperature (above 600℃) to achieve a higher growth rate and better crystal quality.
[0006] Atomic layer deposition of silicon nitride is used as a hard mask for germanium silicon. This silicon nitride, which is deposited with the addition of H, greatly improves the overall etching rate of the film, but there is a problem of large difference in in-plane etching rate, with the etching rate gradually decreasing from the center of the wafer to the periphery. This phenomenon reduces the process window for defects in the germanium silicon layer. Because of the relatively high etching rate at the center of the wafer, after etching of the germanium silicon trench, the germanium silicon hard mask is not thick enough or is missing, exposing the low-k dielectric layer, and the carbon in the film will diffuse out at high temperatures, affecting the uniform growth of germanium silicon, ultimately forming germanium silicon defects (SiGe small) and affecting the yield of the product, as shown in Figure 1 SUMMARY
[0007] In the summary section, a series of simplified concepts are introduced, which are simplifications of the prior art in the field. These will be described in further detail in the detailed description section. The summary section of the present application does not mean to attempt to limit the key features and necessary technical features of the claimed technical solution, nor does it attempt to determine the protection scope of the claimed technical solution.
[0008] The technical problem to be solved by the present application is to provide a silicon nitride hard mask deposition method that can improve the uniformity of the silicon nitride hard mask and avoid the adverse effects of the silicon nitride hard mask as a germanium silicon hard mask on the growth of the germanium silicon layer.
[0009] To solve the above technical problems, the present application provides a method for depositing a silicon nitride hard mask, which is used for a germanium-silicon hard mask, and a furnace tube atomic layer deposition system for depositing silicon nitride, wherein the Plasma (plasma deposition) is turned off, which can effectively reduce Si-H bonds and improve the deposition uniformity of the silicon nitride hard mask.
[0010] Preferably, the method for depositing the silicon nitride hard mask is further improved, and the film forming temperature is always within a first temperature range during the film forming process.
[0011] Preferably, the first temperature range is 570-580 DEG C, so as to balance the deposition rate.
[0012] Preferably, the method for depositing the silicon nitride hard mask is further improved, and the reactant DCS (dichlorosilane) is connected to the furnace tube deposition system in a pulse mode and a direct current mode, so as to improve the deposition efficiency.
[0013] Preferably, the method for depositing the silicon nitride hard mask is further improved, and the reactant DCS (dichlorosilane) is connected to the furnace tube deposition system in a pulse mode and a direct current mode, so as to improve the deposition efficiency.
[0014] Preferably, the method for depositing the silicon nitride hard mask is further improved, and the reactant DCS (dichlorosilane) is connected to the furnace tube deposition system in a pulse mode and a direct current mode.
[0015] Optionally, the method for depositing the silicon nitride hard mask is further improved, and the pulse mode and the direct current mode include:
[0016] In one production cycle, the total time for connecting the reactant DCS to the furnace tube deposition system is divided into multiple equal sub-periods.
[0017] The pulse mode and the direct current mode are alternately executed in each sub-period.
[0018] Optionally, the method for depositing the silicon nitride hard mask is further improved, and the pulse mode and the direct current mode include:
[0019] In one production cycle, the total time for connecting the reactant DCS to the furnace tube deposition system is divided into multiple equal sub-periods.
[0020] The reactant DCS (dichlorosilane) is connected to the furnace tube deposition system in a pulse mode and a direct current mode alternately.
[0021] Connecting the reactant DCS to the furnace tube deposition system in a pulse mode and a direct current mode can improve the reaction efficiency, accurately control the reaction conditions, and reduce the occurrence of impurities and side reactions.
[0022] The present application improves the deposition process of the silicon nitride hard mask in order to avoid the phenomenon that the silicon nitride hard mask as a germanium silicon hard mask is not thick enough or missing due to large difference in in-plane etching rate, and to avoid the carbon in the germanium silicon hard mask diffusing out at high temperature, thereby affecting the uniform growth of germanium silicon. The present application effectively reduces Si-H bonds by closing the Plasma to improve the deposition uniformity of the silicon nitride hard mask, ensures the balance of the deposition rate by controlling the film formation temperature, improves the deposition uniformity of the silicon nitride hard mask by increasing the NH3 input time, and improves the deposition uniformity of the silicon nitride by using at least one of the following technical means or their combination: pulse type joint, direct current type input of reactant DCS, etc., thereby improving the germanium silicon hard mask, avoiding the formation of germanium silicon defects (tiny defect and SiGe small), improving the yield of the product, and the like. Figure 2 and Figure 3 . BRIEF DESCRIPTION OF DRAWINGS
[0023] The drawings of the present application are intended to show the general characteristics of the methods, structures and / or materials used in the specific exemplary embodiments according to the present application, and to supplement the description in the specification. However, the drawings of the present application are schematic drawings that are not drawn to scale, and therefore may not accurately reflect the precise structure or performance characteristics of any given embodiment, and the drawings of the present application should not be interpreted as limiting or restricting the scope of the values or attributes encompassed by the exemplary embodiments according to the present application. The present application is further described in detail below in conjunction with the specific embodiments and the accompanying drawings:
[0024] Figure 1 is a schematic diagram of the defects of the prior art germanium silicon hard mask, and the circled position is the silicon nitride defect.
[0025] Figure 2 is a schematic diagram of the comparison effect of the prior art and the present application Figure 1 .
[0026] Figure 3 is a schematic diagram of the comparison effect of the prior art and the present application Figure 2 . DETAILED DESCRIPTION
[0027] The present application is further explained in the following detailed description with reference to the accompanying drawings, wherein: Other advantages and features of the present application will be apparent from this description and the drawings, and from the claims. The present application can be embodied in various specific forms without departing from the general scope of the inventive concepts presented herein. The specific embodiments of the present application as set forth for the purposes of example and illustration only are not intended to be limiting in any way, as are all equivalents of these described embodiments. It is to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting. It is to be understood that where the application is specifically described herein with reference to particular aspects, embodiments, or examples, that such specific description is for the purpose of illustration only and is not intended to limit the scope of the application. It is to be understood that the use of "including", "comprising", or "having" and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. It is to be understood that the use of "including", "comprising", or "having" and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items.
[0028] Firstly, it needs to be explained that the present application improves the process of depositing silicon nitride by furnace tube atomic layer deposition system from four aspects, and the four aspects form the following four embodiments. The four embodiments can be used in any combination to solve the technical problems to be solved by the present application, and the difference between them is that the technical effects are slightly different.
[0029] The four aspects, i.e. the following four embodiments, can also be used in any combination, for example, the first embodiment and the second embodiment are combined to form an improvement scheme, the first embodiment and the third embodiment are combined to form an improvement scheme, the first embodiment and the fourth embodiment are combined to form an improvement scheme, etc. Correspondingly, the four aspects, i.e. the following four embodiments, have the best technical effect when they work together.
[0030] First embodiment;
[0031] The present application is a method for depositing a silicon nitride hard mask, which is used for a germanium-silicon hard mask. When the furnace tube atomic layer deposition system deposits silicon nitride, the Plasma is turned off.
[0032] Second embodiment;
[0033] The present application is a method for depositing a silicon nitride hard mask, which is used for a germanium-silicon hard mask. When the furnace tube deposition system deposits silicon nitride, the film forming temperature is always within the first temperature range during the film forming process.
[0034] The first temperature range is 570-580 DEG C, and the first temperature is preferably any integer within the aforementioned range.
[0035] The third embodiment;
[0036] The present application discloses a method for depositing silicon nitride hard mask, when the furnace tube deposition system deposits silicon nitride, the reactant DCS (dichlorosilane) is connected to the furnace tube deposition system by pulse and direct current.
[0037] Alternatively, the reactant DCS (dichlorosilane) is connected to the furnace tube deposition system by pulse and direct current.
[0038] Alternatively, the pulse and direct current connection includes:
[0039] In one production cycle, the total time of connecting the reactant DCS to the furnace tube deposition system is divided into multiple equal sub-periods.
[0040] The pulse and direct current are alternately executed in each sub-period.
[0041] Alternatively, the pulse and direct current connection includes: in one production cycle, the total time of connecting the reactant DCS to the furnace tube deposition system is divided into multiple equal sub-periods.
[0042] The reactant DCS (dichlorosilane) is connected to the furnace tube deposition system by pulse and direct current alternately in two sub-periods.
[0043] The fourth embodiment;
[0044] The present application discloses a method for depositing silicon nitride hard mask, when the furnace tube deposition system deposits silicon nitride, the reactant DCS (dichlorosilane) is connected to the furnace tube deposition system by pulse and direct current.
[0045] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.
[0046] The application has been described in detail by specific implementation and examples, but these do not constitute a limitation on the application. Those skilled in the art can also make many modifications and improvements without departing from the principles of the application, and these should also be considered as the protection scope of the application.
Claims
1. A method for depositing a silicon nitride hard mask, wherein the silicon nitride hard mask is used for a germanium-silicon hard mask, characterized in that: When depositing silicon nitride using the furnace tube atomic layer deposition system, turn off Plasma.
2. The silicon nitride hard mask deposition method as described in claim 1, characterized in that, Also includes: During the film formation process, the film formation temperature remains within the first temperature range.
3. The silicon nitride hard mask deposition method as described in claim 1, characterized in that, Also includes: The reactant DCS (dichlorosilane) is introduced into the furnace tube deposition system using a pulsed, direct-flow injection method.
4. The silicon nitride hard mask deposition method as described in claim 1, characterized in that, Also includes: The reaction gas source NH3 is introduced for a time ranging from 20 to 40 seconds.
5. The silicon nitride hard mask deposition method as described in claim 2, characterized in that: The first temperature range is 570°C to 580°C.
6. The silicon nitride hard mask deposition method as described in claim 3, characterized in that: The reactant DCS (dichlorosilane) is introduced into the furnace tube deposition system using both pulsed and direct current methods.
7. The silicon nitride hard mask deposition method as described in claim 3, characterized in that, The pulse-type DC connection includes: Within a production cycle, the total time for the reactant DCS to be introduced into the furnace tube deposition system is divided into multiple equally divided sub-cycles; Each sub-cycle is executed alternately in pulse and DC modes.
8. The silicon nitride hard mask deposition method as described in claim 3, characterized in that, The pulse-type DC connection includes: Within a production cycle, the total time for the reactant DCS to be introduced into the furnace tube deposition system is divided into multiple equally divided sub-cycles; The reactant DCS (dichlorosilane) is introduced into the furnace tube deposition system in a DC-driven manner with a pulsed manner that alternates between two sub-cycles and one sub-cycle.