Contact hole filling method

Abstract

The invention provides a contact hole filling method. A Co layer is formed on one side of a first oxide layer; forming a lamination layer on the upper surfaces of the first oxide layer and the Co layer, wherein the lamination layer sequentially comprises a first SiN layer, a TiN layer and a second SiN layer from bottom to top; forming a second oxide layer on the laminated layer; removing the second SiN layer and the TiN layer above the Co layer on the first oxide layer, and covering a second oxide layer on the second SiN layer above the first oxide layer and an area where the second SiN layer and the TiN layer above the Co layer are removed; removing the second oxide layer and the second SiN layer above one side, without the Co layer, of the first oxide layer until the upper surface of the TiN layer is exposed, and forming a first contact hole; removing the second oxide layer and the first SiN layer above one side of the first oxide layer with the Co layer until the upper surface of the Co layer is exposed, and forming a second contact hole; forming selective Co layers on the TiN layer at the bottom of the first contact hole and the Co layer at the bottom of the second contact hole respectively; and respectively filling tungsten in the first contact hole and the second contact hole.

Description

Technical Field

[0001] The invention relates to the field of semiconductor technology, and in particular to a contact hole filling method. Background Art

[0002] The existing contact hole V0 process is filled with titanium Ti, titanium nitride TiN, and tungsten W in sequence. Due to the existence of the barrier layer and the nucleation layer Nuc, the contact resistance of the contact hole V0 process is relatively high, which affects the device performance.

[0003] The filling method under development is pretreatment and direct filling of selective tungsten, which can greatly reduce the contact resistance of the contact hole V0 and improve device performance. However, the existing contact hole V0 process wafer has a high resistance trench (HRtrench) and a metal layer trench (M0 trench) Co when filling, wherein the bottom of the HR trench is TiN and the bottom of the metal layer trench is Co. Pretreatment provides nucleation points for tungsten, which enables better selective growth of the M0 trench. However, since the bottom of the HR trench is TiN, the cultivation time of the selective W on TiN is the same as that of silicon oxide, and the conditions for selective growth cannot be achieved. In addition, after pretreatment and the deposition process of selective tungsten, the TiN at the bottom of the HR trench will be damaged, thereby causing high resistance problems.

[0004] The existing solution is to add a cap layer (SiN and Oxide) on the TiN at the bottom of the HR trench. This method not only increases the number of integrated processes (2 depositions, 1 etching, and 1 wet etching), but also makes the etching control of the HR trench etch stop layer more difficult due to the increase in the stacking of film layers, and affects the process window. In addition, the wet etching of the etch stop layer has a greater impact on defect performance. Summary of the invention

[0005] In view of the above-mentioned shortcomings of the prior art, an object of the present invention is to provide a contact hole filling method for solving the problem in the prior art that the contact hole resistance is high and affects the device performance.

[0006] To achieve the above-mentioned object and other related objects, the present invention provides a contact hole filling method, which at least comprises:

[0007] Step 1, providing a first oxide layer, wherein a Co layer embedded in the first oxide layer is formed on one side of the first oxide layer; the Co layer penetrates the upper and lower surfaces of the first oxide layer; forming a stack on the first oxide layer and the upper surface of the Co layer, wherein the stack includes a first SiN layer, a TiN layer and a second SiN layer from bottom to top; and then forming a second oxide layer on the stack;

[0008] Etching and removing the second SiN layer and the TiN layer on the side of the first oxide layer with the Co layer, and then covering the second SiN layer 05 on the side of the first oxide layer without the Co layer and the first SiN layer on the side of the first oxide layer with the Co layer with a second oxide layer;

[0009] Step 3: Remove the second oxide layer and the second SiN layer above the side of the first oxide layer without the Co layer by developing and etching until the upper surface of the TiN layer is exposed, thereby forming a first contact hole, wherein the TiN layer serves as the bottom of the first contact hole; the diameter of the first contact hole is smaller than the width of the first oxide layer;

[0010] Step 4: removing the second oxide layer and the first SiN layer above the Co layer on the first oxide layer by developing and etching until the upper surface of the Co layer is exposed, thereby forming a second contact hole; the diameter of the second contact hole is smaller than the width of the Co layer;

[0011] Step 5, forming a selective Co layer on the TiN layer at the bottom of the first contact hole and the Co layer at the bottom of the second contact hole respectively;

[0012] Step six: filling tungsten into the first contact hole and the second contact hole respectively.

[0013] Preferably, in step 2, the width of the first oxide layer is its width in a transverse plane.

[0014] Preferably, the width of the Co layer in step 4 is its width in the transverse plane.

[0015] Preferably, in step five, a selective deposition method is used to form a selective Co layer on the TiN layer at the bottom of the first contact hole and the Co layer at the bottom of the second contact hole, respectively.

[0016] Preferably, in step six, tungsten is respectively filled into the first contact hole and the second contact hole by a selective deposition method.

[0017] Preferably, the selective Co layer formed on the TiN layer at the bottom of the first contact hole in step five is used to protect the TiN layer at the bottom of the first contact hole from damage and avoid high resistance.

[0018] Preferably, in step five, a selective Co layer is formed on the TiN layer at the bottom of the first contact hole and the Co layer at the bottom of the second contact hole in the same process.

[0019] As described above, the contact hole filling method of the present invention has the following beneficial effects: the present invention solves the problem that the high resistance trench HR trench cannot grow selective tungsten, and for pretreatment, there is no need to consider the loss of TiN, the process is more adjustable, and for integration, only the thin film deposition step is added, which has little impact, and the formation of selective tungsten can be achieved, which can greatly reduce the V0 resistance value and improve device performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic diagram showing the structure of forming the first contact hole and the second contact hole in the present invention;

[0021] Figure 2 It is a schematic diagram of the structure after a selective Co layer is formed at the bottom of the first contact hole and the second contact hole in the present invention;

[0022] Figure 3 It is a schematic diagram of the structure after tungsten is filled in the first contact hole and the second contact hole respectively in the present invention;

[0023] Figure 4 Shown is a flow chart of the contact hole filling method in the present invention. DETAILED DESCRIPTION

[0024] The following describes the embodiments of the present invention through specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention.

[0025] See also Figures 1 to 4 It should be noted that the illustrations provided in this embodiment are only used to schematically illustrate the basic concept of the present invention, and the drawings only show components related to the present invention rather than being drawn according to the number, shape and size of components in actual implementation. In actual implementation, the type, quantity and proportion of each component may be changed arbitrarily, and the component layout may also be more complicated.

[0026] The present invention provides a contact hole filling method, such as Figure 4 As shown, Figure 4 The flow chart of the contact hole filling method in the present invention is shown, and the method at least comprises the following steps:

[0027] Step 1: providing a first oxide layer, wherein a Co layer embedded in the first oxide layer is formed on one side of the first oxide layer; the Co layer penetrates the upper and lower surfaces of the first oxide layer; forming a stack on the first oxide layer and the upper surface of the Co layer, wherein the stack includes a first SiN layer, a TiN layer and a second SiN layer from bottom to top; and then forming a second oxide layer on the stack; Figure 1 As shown, Figure 1 The diagram shows a schematic diagram of a structure for forming a first contact hole and a second contact hole in the present invention. The first contact hole in the present invention is also called a high resistance trench, and the second contact hole is also called a metal layer trench.

[0028] In step 1, a first oxide layer 01 is provided, and a Co layer 02 embedded in the first oxide layer 01 is formed on one side of the first oxide layer 01; the Co layer 02 penetrates the upper and lower surfaces of the first oxide layer 01; then a stack is formed on the upper surfaces of the first oxide layer 01 and the Co layer 02, and the stack includes a first SiN layer 03, a TiN layer 04, and a second SiN layer 05 from bottom to top; Figure 1 The first SiN layer 03, the TiN layer 04 and the second SiN layer 05 have been etched. Figure 1 The first SiN layer 03, TiN layer 04 and second SiN layer 05 are not shown when they are not etched. Therefore, the first SiN layer 03, TiN layer 04 and second SiN layer 05 in step 1 are not etched. Step 1 After forming the stack, a second oxide layer 06 is formed on the stack. Figure 1 The second oxide layer 06 has been etched, so Figure 1 The second oxide layer 06 which has not been etched is not shown in the figure, so the second oxide layer 06 in step 1 means that it has not been etched.

[0029] Step 2: etching and removing the second SiN layer and the TiN layer on the side of the first oxide layer with the Co layer, and then covering the second SiN layer on the side of the first oxide layer without the Co layer and the first SiN layer on the side of the first oxide layer with the Co layer with a second oxide layer;

[0030] Furthermore, in the present invention, in step 2 of this embodiment, the width of the first oxide layer is its width in a transverse plane.

[0031] like Figure 1 As shown, in step 2, the second SiN layer 05 and the TiN layer 04 on the side of the first oxide layer 01 with the Co layer 02 are etched away, and then the second oxide layer 06 is covered on the second SiN layer 05 on the side of the first oxide layer 01 without the Co layer and on the first SiN layer 03 on the side of the first oxide layer with the Co layer;

[0032] In this embodiment, the width of the first oxide layer is its width in a transverse plane. In this embodiment, the first oxide layer is located on a wafer, and its width in a transverse plane refers to the width occupied by the wafer plane.

[0033] Step three, developing and etching to remove the second oxide layer and the second SiN layer above the side of the first oxide layer without the Co layer until the upper surface of the TiN layer is exposed, forming a first contact hole, and the TiN layer serves as the bottom of the first contact hole; the diameter of the first contact hole is smaller than the width of the first oxide layer; the diameter of the first contact hole 07 is smaller than the width of the first oxide layer 01, that is, the diameter of the first contact hole 07 here refers to the diameter of the bottom of the first contact hole; in step three, developing and etching to remove the second oxide layer 06 and the second SiN layer 05 above the side of the first oxide layer 01 without the Co layer until the upper surface of the TiN layer 04 is exposed, forming a first contact hole 07, and the TiN layer 04 serves as the bottom of the first contact hole 07; the diameter of the first contact hole 07 is smaller than the width of the first oxide layer 01.

[0034] Step 4: removing the second oxide layer and the first SiN layer above the Co layer on the first oxide layer by developing and etching until the upper surface of the Co layer is exposed, thereby forming a second contact hole; the diameter of the second contact hole is smaller than the width of the Co layer; Figure 1 In the step 4, the second oxide layer 06 and the first SiN layer 03 on one side of the first oxide layer 01 are etched in sequence after development until the upper surface of the Co layer 02 is exposed, thereby forming a second contact hole 08; the diameter of the second contact hole 08 is smaller than the width of the Co layer 02. In the present invention, further, the width of the Co layer 02 in step 4 of this embodiment is its width in the transverse plane. That is to say, the diameter of the second contact hole 08 here refers to the diameter of the bottom of the second contact hole 08; the width of the Co layer 02 in this embodiment is its width in the transverse plane, and the Co layer 02 in this embodiment is located on the wafer, and its width in the transverse plane refers to the width of the wafer plane occupied.

[0035] Step 5, forming a selective Co layer on the TiN layer at the bottom of the first contact hole and the Co layer at the bottom of the second contact hole respectively;

[0036] According to the present invention, in step five of this embodiment, a selective deposition method is used to form a selective Co layer on the TiN layer at the bottom of the first contact hole and the Co layer at the bottom of the second contact hole.

[0037] Furthermore, in the present invention, the selective Co layer formed on the TiN layer at the bottom of the first contact hole in step five of this embodiment is used to protect the TiN layer at the bottom of the first contact hole from damage and avoid high resistance.

[0038] According to the present invention, in step five of this embodiment, a selective Co layer is formed on the TiN layer at the bottom of the first contact hole and the Co layer at the bottom of the second contact hole in the same process.

[0039] like Figure 2 As shown, Figure 2 It shows a schematic diagram of the structure after the selective Co layer is formed at the bottom of the first contact hole and the second contact hole in the present invention. In step five, a selective Co layer is formed on the TiN layer 04 at the bottom of the first contact hole 07 and the Co layer 02 at the bottom of the second contact hole 08; in step five of this embodiment, a selective deposition method is used to form a selective Co layer on the TiN layer 04 at the bottom of the first contact hole 07 and the Co layer 02 at the bottom of the second contact hole 08, wherein a selective Co layer 09 is formed on the TiN layer 04 at the bottom of the first contact hole 07, and a selective Co layer 10 is formed on the Co layer 02 at the bottom of the second contact hole 08. In step five of this embodiment, the selective Co layer 09 formed on the TiN layer 04 at the bottom of the first contact hole 07 is used to protect the TiN layer 04 at the bottom of the first contact hole 07 from damage and avoid high resistance. In step five of this embodiment, a selective Co layer is formed on the TiN layer 04 at the bottom of the first contact hole 07 and the Co layer 02 at the bottom of the second contact hole 08 in the same process.

[0040] Step six: filling tungsten into the first contact hole and the second contact hole respectively.

[0041] According to the present invention, in step six of this embodiment, tungsten is respectively filled in the first contact hole and the second contact hole using a selective deposition method.

[0042] like Figure 3 As shown, Figure 3 It is a schematic diagram of the structure after tungsten is filled in the first contact hole and the second contact hole in the present invention. In step 6, tungsten is filled in the first contact hole and the second contact hole respectively. In step 6 of this embodiment, tungsten is filled in the first contact hole and the second contact hole respectively by a selective deposition method. Tungsten 11 is filled in the first contact hole, and tungsten 12 is filled in the second contact hole.

[0043] Since selective Co is an electron donor in its growth mechanism, the TiN at the bottom of the high-resistance trench and the Co surface at the bottom of the metal trench can provide free electrons for the growth of Co molecules, and they will not grow on the dielectric layer SiN and the silicon oxide surface. Therefore, in the selective tungsten process, before growing the selective tungsten, a thin layer of selective Co is grown on the TiN surface. In this way, when growing selective tungsten, both the high-resistance trench and the bottom of the metal layer trench are Co films, which can achieve the conditions for the selective growth of tungsten and solve the problem that the high-resistance trench cannot grow selective tungsten. In addition, for pretreatment, there is no need to consider the loss of TiN, and the process is more adjustable. For integration, only one thin film deposition step is added, which has little impact, making the selective tungsten process feasible, which can greatly reduce the contact hole resistance and improve device performance.

[0044] In summary, the present invention solves the problem that high-resistance trenches cannot grow selective tungsten, and for pretreatment, there is no need to consider the loss of TiN, the process is more adjustable, and for integration, only the thin film deposition step is added, which has little impact, and can achieve the formation of selective tungsten, which can greatly reduce the V0 resistance and improve device performance. Therefore, the present invention effectively overcomes various shortcomings in the prior art and has a high industrial utilization value.

[0045] 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 familiar with 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 a person of ordinary skill in the art without departing from the spirit and technical concept disclosed by the present invention shall still be covered by the claims of the present invention.

Claims

1. A contact hole filling method, characterized in that: At least: Step 1, providing a first oxide layer, wherein a Co layer embedded in the first oxide layer is formed on one side of the first oxide layer; the Co layer penetrates the upper and lower surfaces of the first oxide layer; forming a stack on the first oxide layer and the upper surface of the Co layer, wherein the stack includes a first SiN layer, a TiN layer and a second SiN layer from bottom to top; and then forming a second oxide layer on the stack; Step 2: etching and removing the second SiN layer and the TiN layer on the side of the first oxide layer with the Co layer, and then covering the second SiN layer on the side of the first oxide layer without the Co layer and the first SiN layer on the side of the first oxide layer with the Co layer with a second oxide layer; Step 3: Remove the second oxide layer and the second SiN layer above the side of the first oxide layer without the Co layer by developing and etching until the upper surface of the TiN layer is exposed, thereby forming a first contact hole, wherein the TiN layer serves as the bottom of the first contact hole; the diameter of the first contact hole is smaller than the width of the first oxide layer; Step 4: removing the second oxide layer and the first SiN layer above the Co layer on the first oxide layer by developing and etching until the upper surface of the Co layer is exposed, thereby forming a second contact hole; the diameter of the second contact hole is smaller than the width of the Co layer; Step 5, forming a selective Co layer on the TiN layer at the bottom of the first contact hole and the Co layer at the bottom of the second contact hole respectively; Step six: filling tungsten into the first contact hole and the second contact hole respectively.

2. The contact hole filling method according to claim 1, characterized in that: In step 2, the width of the first oxide layer is its width in the transverse plane.

3. The contact hole filling method according to claim 1, characterized in that: The width of the Co layer in step 4 is its width in the transverse plane.

4. The contact hole filling method according to claim 1, characterized in that: In step five, a selective Co layer is formed on the TiN layer at the bottom of the first contact hole and the Co layer at the bottom of the second contact hole respectively by a selective deposition method.

5. The contact hole filling method according to claim 1, characterized in that: In step six, tungsten is respectively filled into the first contact hole and the second contact hole by using a selective deposition method.

6. The contact hole filling method according to claim 1, characterized in that: The selective Co layer formed on the TiN layer at the bottom of the first contact hole in step five is used to protect the TiN layer at the bottom of the first contact hole from damage and avoid high resistance.

7. The contact hole filling method according to claim 1, characterized in that: In step five, a selective Co layer is formed on the TiN layer at the bottom of the first contact hole and the Co layer at the bottom of the second contact hole in the same process.

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