Contact hole manufacturing method and semiconductor device

Abstract

The invention relates to the field of integrated circuit manufacturing, and discloses a contact hole manufacturing method and a semiconductor device, and the method comprises the steps: carrying out the etching of a dielectric layer of a prefabricated semiconductor structural member; in a region corresponding to the barrier layer, etching is stopped to the barrier layer; in a region corresponding to the metal gate, etching is stopped to the interior of the metal gate; the prefabricated semiconductor structural member comprises a metal gate, a barrier layer and a dielectric layer; completely removing oxide formed in the etching process in the metal gate by using a weakly alkaline solution; continuously etching the etched prefabricated semiconductor structural member by using gas without oxidizing property to form a contact hole; the barrier layer is completely etched in a region corresponding to the barrier layer; and etching in a region corresponding to the metal gate and stopping to the interior of the metal gate. According to the invention, the weak alkaline solution is used for removing the oxide after the primary etching, and then the gas without oxidizing property is used for etching, so that the contact hole is prevented from forming the oxide in the metal gate region, the contact resistance is reduced, and the performance and the yield of the device are improved.

Description

Technical Field

[0001] The present application relates to the field of integrated circuit manufacturing, and in particular to a contact hole manufacturing method and a semiconductor device. Background Art

[0002] As the feature size of logic IC (Integrated Circuit) chips continues to shrink, High-k-Metal-Gate (high dielectric constant metal gate) is often used as an integrated solution to deal with the difficulty of further thinning the gate oxide thickness, as well as the rake effect caused by conventional polysilicon gates after the introduction of High-k materials. The commonly used material for metal gates is aluminum.

[0003] Using aluminum as the metal gate also brings an important problem. That is, during the process of etching contact holes, aluminum reacts with oxygen in the etching gas to generate high-resistance aluminum oxide (Al2O3), which in turn causes high resistance in the contact holes, affecting device performance and product yield.

[0004] Therefore, how to solve the above technical problems should be the focus of technical personnel in this field. Summary of the invention

[0005] The purpose of the present application is to provide a contact hole manufacturing method and a semiconductor device to avoid the generation of high-resistance oxide in the contact hole and reduce the contact resistance.

[0006] In order to solve the above technical problems, the present application provides a contact hole manufacturing method, comprising:

[0007] Etching the dielectric layer of the prefabricated semiconductor structure; in the area corresponding to the barrier layer, the etching stops at the barrier layer; in the area corresponding to the metal gate, the etching stops inside the metal gate; the prefabricated semiconductor structure includes the metal gate, the barrier layer located on the side of the metal gate, and the dielectric layer covering the metal gate and the barrier layer;

[0008] Using a weak alkaline solution to completely remove the oxide formed in the metal gate during etching;

[0009] The etched prefabricated semiconductor structure is further etched using a non-oxidizing gas to form a contact hole; in the area corresponding to the barrier layer, the barrier layer is completely etched; in the area corresponding to the metal gate, the etching stops inside the metal gate.

[0010] Optionally, using a weak alkaline solution to completely remove the oxide formed in the metal gate during etching includes:

[0011] An ammonia solution is used to completely remove the oxide formed in the metal gate during etching.

[0012] Optionally, using a weak alkaline solution to completely remove the oxide formed in the metal gate during etching includes:

[0013] A weak alkaline solution is used to ultrasonically clean the oxide formed in the metal gate during etching.

[0014] Optionally, before completely removing the oxide formed in the metal gate during etching using a weak alkaline solution, the method further includes:

[0015] Use a weak alkaline solution to spray or soak the area where the oxide is located.

[0016] Optionally, the mass concentration of the ammonia solution is in the range of 0.34% to 0.68%.

[0017] Optionally, after completely removing the oxide formed in the metal gate during etching using a weak alkaline solution, the method further comprises:

[0018] The prefabricated semiconductor structure is cleaned with deionized water to remove the oxide, and then dried.

[0019] Optionally, using a weak alkaline solution to ultrasonically clean the oxide formed in the metal gate during etching includes:

[0020] Use a weak alkaline solution to spray or soak the area where the oxide is located;

[0021] A weak alkaline solution is used to ultrasonically dissolve oxide formed in the metal gate during etching.

[0022] Optionally, continuing to etch the etched prefabricated semiconductor structure using a non-oxidizing gas includes:

[0023] The etched prefabricated semiconductor structure is further etched using a combination gas of CF4 and CH3F or a combination gas of CF4 and CH2F2.

[0024] Optionally, in the combined gas of CF4 and CH3F, the flow ratio of CF4 gas to CH3F gas ranges from 5:1 to 10:1; in the combined gas of CF4 and CH2F2, the flow ratio of CF4 gas to CH2F2 gas ranges from 5:1 to 10:1.

[0025] The present application also provides a semiconductor device, which includes a contact hole, and the contact hole is made by using any of the contact hole making methods described above.

[0026] The present application provides a contact hole manufacturing method, comprising: etching a dielectric layer of a prefabricated semiconductor structure; in an area corresponding to a barrier layer, etching stops at the barrier layer; in an area corresponding to a metal gate, etching stops inside the metal gate; the prefabricated semiconductor structure comprises the metal gate, the barrier layer located on the side of the metal gate, and the dielectric layer covering the metal gate and the barrier layer; using a weak alkaline solution to completely remove the oxide formed in the metal gate during etching; using a non-oxidizing gas to continue etching the etched prefabricated semiconductor structure to form a contact hole; in an area corresponding to the barrier layer, the barrier layer is completely etched; in an area corresponding to the metal gate, etching stops inside the metal gate.

[0027] It can be seen that in the present application, when making the contact hole, an etching is first performed, and the area corresponding to the contact hole is etched into the metal gate. After etching, oxides will be generated in the metal gate, and then a weak alkaline solution is used to remove the oxides in the contact hole in the metal gate area. At the same time, the weak alkaline solution will not affect the metal gate and the dielectric layer. Finally, a non-oxidizing gas is used to continue etching. Since the gas is non-oxidizing, oxides will not be formed again in the contact hole in the metal gate area, thereby avoiding the generation of high-resistance oxides, effectively reducing contact resistance, and improving device performance and yield. In addition, during the first etching, etching directly to the barrier layer in the area corresponding to the barrier layer can be achieved through selective etching, which can reduce the difficulty of etching. During the second etching, the barrier layer is completely etched through in the area corresponding to the barrier layer to achieve the opening of the contact hole.

[0028] In addition, the present application also provides a semiconductor device having the above advantages. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the embodiments of the present application or the technical solutions of the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0030] Figure 1 A flow chart of a contact hole manufacturing method provided in an embodiment of the present application;

[0031] Figures 2 to 5 A process flow chart of a contact hole manufacturing method provided in an embodiment of the present application. DETAILED DESCRIPTION

[0032] In order to enable those skilled in the art to better understand the present application, the present application is further described in detail below in conjunction with the accompanying drawings and specific implementation methods. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without making creative work are within the scope of protection of the present application.

[0033] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein, and those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0034] As described in the background technology section, aluminum is currently used as the metal gate. During the process of etching contact holes, aluminum reacts with oxygen in the etching gas to generate high-resistance aluminum oxide, which in turn causes high resistance in the contact holes, affecting device performance and product yield.

[0035] In view of this, the present application provides a contact hole manufacturing method, please refer to Figure 1 , the method comprising:

[0036] Step S101: etching the dielectric layer of the prefabricated semiconductor structure; in the area corresponding to the barrier layer, the etching stops at the barrier layer; in the area corresponding to the metal gate, the etching stops inside the metal gate;

[0037] The prefabricated semiconductor structure includes the metal gate, the barrier layer located on the side of the metal gate, and the dielectric layer covering the metal gate and the barrier layer.

[0038] The schematic diagram of the structure of the prefabricated semiconductor structure is as follows Figure 2 As shown, it includes a substrate 1, a metal gate 4, a barrier layer 3, a silicide layer 2 and a dielectric layer 5, wherein the metal gate 4 and the silicide layer 2 are located on the upper surface of the substrate 1, the barrier layer 3 is stacked on the silicide layer 2, and the dielectric layer 5 covers the metal gate 4 and the barrier layer 3. Among them, the metal gate 4 is an aluminum gate, the barrier layer 3 is a silicon nitride layer, and the dielectric layer 5 is a silicon dioxide layer.

[0039] Please refer to Figure 3The etching gas in this step includes oxygen. In the process of etching to form the contact hole, in the area corresponding to the metal gate 4, etching is performed downward from the dielectric layer 5 to the metal gate 4 area. In the metal gate 4 area, the metal gate 4 reacts with oxygen to generate oxide 6 (Al2O3); in the area corresponding to the barrier layer 3, etching is performed downward from the dielectric layer 5. The etching stop position can be at the interface between the barrier layer 3 and the dielectric layer 5 (that is, the upper surface of the barrier layer), or slightly lower than the upper surface of the barrier layer 3, that is, a portion of the barrier layer 3 is slightly etched away during etching.

[0040] Step S102: using a weak alkaline solution to completely remove the oxide formed in the metal gate during etching.

[0041] The reason for using a weak alkaline solution to remove oxides in this step is that the oxides can be dissolved by reacting with the weak alkaline solution, and at the same time, the weak alkaline solution will not corrode the dielectric layer outside the contact hole, nor will it react with the metal gate.

[0042] In one embodiment of the present application, before completely removing the oxide formed in the metal gate during etching using a weak alkaline solution, the method may further include:

[0043] Use a weak alkaline solution to spray or soak the area where the oxide is located.

[0044] Spraying or soaking the oxidized area with weak alkalinity in advance can speed up the removal of the oxide, wherein the spraying or soaking time can be 3 to 5 minutes.

[0045] Please refer to Figure 4 , the oxide is completely removed. This step of removing oxide can be carried out at room temperature.

[0046] The present application does not limit the type of weak alkaline solution, and the solution can be selected at will.

[0047] As an implementation method, using a weak alkaline solution to completely remove the oxide formed in the metal gate during etching includes:

[0048] An ammonia solution is used to completely remove the oxide formed in the metal gate during etching.

[0049] The mass concentration of the ammonia solution may be in the range of 0.34% to 0.68%, for example, the mass concentration of the ammonia solution is 0.34%, 0.5%, 0.6%, 0.68%, etc.

[0050] In order to speed up the removal of oxides and improve the manufacturing efficiency of contact holes, in one embodiment of the present application, using a weak alkaline solution to completely remove the oxides formed in the metal gate during etching includes:

[0051] A weak alkaline solution is used to ultrasonically clean the oxide formed in the metal gate during etching.

[0052] In one embodiment of the present application, using a weak alkaline solution to ultrasonically clean the oxide formed in the metal gate during etching includes:

[0053] Use a weak alkaline solution to spray or soak the area where the oxide is located;

[0054] A weak alkaline solution is used to ultrasonically dissolve oxide formed in the metal gate during etching.

[0055] The spraying or soaking time can be 3 to 5 minutes. The weak alkaline solution can be sprayed or soaked in the area where the oxide is located, and the ultrasonic dissolution process can be carried out at the same time.

[0056] Step S103: continue etching the etched prefabricated semiconductor structure using a non-oxidizing gas to form a contact hole; in the area corresponding to the barrier layer, the barrier layer is completely etched; in the area corresponding to the metal gate, the etching stops inside the metal gate.

[0057] Please refer to Figure 5 After etching in this step, the barrier layer 3 is completely opened. The etching gas does not include oxygen, so no oxide is generated in the contact hole in the metal gate region.

[0058] As an implementation method, continuing to etch the etched prefabricated semiconductor structure using a non-oxidizing gas includes:

[0059] The etched prefabricated semiconductor structure is further etched using a combination gas of CF4 (carbon tetrafluoride, also known as tetrafluoromethane) and CH3F (fluoromethane) or a combination gas of CF4 and CH2F2 (difluoromethane).

[0060] Among them, in the combined gas of CF4 and CH3F, the flow ratio of CF4 gas to CH3F gas ranges from 5:1 to 10:1; in the combined gas of CF4 and CH2F2, the flow ratio of CF4 gas to CH2F2 gas ranges from 5:1 to 10:1.

[0061] For example, when the etching gas is a combination gas of CF4 and CH3F, the flow ratio of CF4 gas to CH3F gas can be 5:1, 6:1, 7:1, 8:1, 9:1, 10:1, etc.; when the etching gas is a combination gas of CF4 and CH2F2, the flow ratio of CF4 gas to CH2F2 gas can be 5:1, 6:1, 7:1, 8:1, 9:1, 10:1, etc.

[0062] In this embodiment, when making the contact hole, an etching is first performed, and the area corresponding to the contact hole is etched into the metal gate. After etching, oxides will be generated in the metal gate, and then a weak alkaline solution is used to remove the oxides in the contact hole in the metal gate area. At the same time, the weak alkaline solution will not affect the metal gate and the dielectric layer. Finally, a non-oxidizing gas is used to continue etching. Since the gas is non-oxidizing, oxides will not be formed again in the contact hole in the metal gate area, thereby avoiding the generation of high-resistance oxides, effectively reducing contact resistance, and improving device performance and yield. In addition, in the first etching, etching directly to the barrier layer in the area corresponding to the barrier layer can be achieved through selective etching, which can reduce the difficulty of etching. In the second etching, the barrier layer is completely etched through in the area corresponding to the barrier layer to achieve the opening of the contact hole.

[0063] Based on any of the above embodiments, in one embodiment of the present application, after completely removing the oxide formed in the metal gate during etching using a weak alkaline solution, the method further includes:

[0064] The prefabricated semiconductor structure is cleaned with deionized water to remove the oxide, and then dried.

[0065] The residual weak alkaline solution and reaction by-products are cleaned with deionized water and then dried.

[0066] The contact hole manufacturing method in the present application is described below using a specific case.

[0067] Step 1: Prepare Figure 2 The prefabricated semiconductor structure shown;

[0068] Step 2, performing the first etching, etching the area corresponding to the metal gate into the metal gate, and etching the area corresponding to the barrier layer to the upper surface of the barrier layer;

[0069] Step 3: Soak the area where the oxide is generated in the metal gate with an ammonia solution, then turn on the ultrasound and use the ammonia solution for ultrasonic cleaning to completely remove the oxide;

[0070] Step 4: washing with deionized water to remove the remaining ammonia and by-products of the reaction, and drying;

[0071] Step 5: Use a non-oxidizing gas to etch the area corresponding to the barrier layer again, and stop etching at the lower surface of the barrier layer, so as to completely open the barrier layer and obtain a contact hole.

[0072] The present application also provides a semiconductor device, which includes a contact hole, and the contact hole is made by using the contact hole making method described in any of the above embodiments.

[0073] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0074] The contact hole manufacturing method and semiconductor device provided by the present application are introduced in detail above. Specific examples are used in this article to illustrate the principles and implementation methods of the present application. The description of the above embodiments is only used to help understand the method and core idea of ​​the present application. It should be pointed out that for ordinary technicians in this technical field, without departing from the principles of the present application, several improvements and modifications can be made to the present application, and these improvements and modifications also fall within the scope of protection of the claims of the present application.

Claims

1. A contact hole manufacturing method, characterized in that: include: Etching a dielectric layer of a prefabricated semiconductor structure; In a region corresponding to the barrier layer, etching stops at the barrier layer; In the area corresponding to the metal gate, the etching stops inside the metal gate; the prefabricated semiconductor structure comprises the metal gate, the barrier layer located on the side of the metal gate, and the dielectric layer covering the metal gate and the barrier layer; Using a weak alkaline solution to completely remove the oxide formed in the metal gate during etching; Using a non-oxidizing gas to continue etching the etched prefabricated semiconductor structure to form a contact hole; In the region corresponding to the barrier layer, the barrier layer is completely etched; and in the region corresponding to the metal gate, the etching stops inside the metal gate.

2. The contact hole manufacturing method according to claim 1, characterized in that: Using a weak alkaline solution to completely remove the oxide formed in the metal gate during etching includes: An ammonia solution is used to completely remove the oxide formed in the metal gate during etching.

3. The contact hole manufacturing method according to claim 1, characterized in that: Using a weak alkaline solution to completely remove the oxide formed in the metal gate during etching includes: A weak alkaline solution is used to ultrasonically clean the oxide formed in the metal gate during etching.

4. The contact hole manufacturing method according to claim 1, characterized in that: Before completely removing the oxide formed in the metal gate during etching using a weak alkaline solution, the method further includes: Use a weak alkaline solution to spray or soak the area where the oxide is located.

5. The contact hole manufacturing method according to claim 2, characterized in that: The mass concentration of the ammonia solution is in the range of 0.34% to 0.68%.

6. The contact hole manufacturing method according to claim 1, characterized in that: After completely removing the oxide formed in the metal gate during etching using a weak alkaline solution, the method further includes: The prefabricated semiconductor structure is cleaned with deionized water to remove the oxide, and then dried.

7. The contact hole manufacturing method according to claim 3, characterized in that: Using a weak alkaline solution to ultrasonically clean the oxide formed in the metal gate during etching includes: Use a weak alkaline solution to spray or soak the area where the oxide is located; A weak alkaline solution is used to ultrasonically dissolve oxide formed in the metal gate during etching.

8. The contact hole manufacturing method according to any one of claims 1 to 7, characterized in that: The process of further etching the etched prefabricated semiconductor structure using a non-oxidizing gas includes: The etched prefabricated semiconductor structure is further etched using a combination gas of CF4 and CH3F or a combination gas of CF4 and CH2F2.

9. The contact hole manufacturing method according to claim 8, characterized in that: In the combined gas of CF4 and CH3F, the flow ratio of CF4 gas to CH3F gas ranges from 5:1 to 10:1; in the combined gas of CF4 and CH2F2, the flow ratio of CF4 gas to CH2F2 gas ranges from 5:1 to 10:

1.

10. A semiconductor device, characterized in that: The semiconductor device comprises a contact hole, and the contact hole is made by using the contact hole making method according to any one of claims 1 to 9.

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